ELECTRIC PUMP AND CONTROL DEVICE

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2024-179793, filed on Oct. 15, 2024, the entire contents of which are hereby incorporated herein by reference.

1. Field of the Invention

The present disclosure relates to electric pumps and controllers.

2. Background

A pump is known to have a configuration in which a shaft that transmits a rotational torque of a rotor to the pump is rotatably supported by a main body inner tubular portion of a housing.

In the above-described pump, when the amount of fluid such as oil interposed between the shaft and the main body inner tubular portion decreases, the lubrication performance between the shaft and the main body inner tubular portion by the fluid is decreased, leading to an increase in the frictional force between the shaft and the main body inner tubular portion. When the pump is continuously operated in such a state, there is a possibility that the pump fails due to wearing of at least one of the shaft or the main body inner tubular portion, seizure of the shaft to the main body inner tubular portion, and the like.

SUMMARY

An electric pump according to an example embodiment of the present disclosure includes a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and drivable by the motor assembly to pump a fluid, a housing to accommodate the motor assembly and the pump assembly, and a controller configured or programmed to control an operation of the motor assembly. The housing includes a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft. The fluid is interposed between the shaft and the sliding shaft supporting portion. The controller is configured or programmed to determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion based on a first variation value that is a variation value of a rotational speed of the shaft, a second variation value that is a variation value of a current supplied to the motor assembly, or a third variation value that is a variation value of a voltage applied to the controller, in a first predetermined period in which a target rotational speed of the shaft is a constant speed.

A controller according to an example embodiment of the present disclosure is configured or programmed to control an operation of an electric pump including a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and driven by power of the motor assembly to pump a fluid, and a housing to accommodate the motor assembly and the pump assembly. The housing includes a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft. The fluid is interposed between the shaft and the sliding shaft supporting portion. An abnormality due to a shortage of the fluid in the sliding shaft supporting portion is determined based on a first variation value that is a variation value of a rotational speed of the shaft, a second variation value that is a variation value of a current supplied to the motor assembly, or a third variation value that is a variation value of a voltage applied to the controller, in a first predetermined period in which a target rotational speed of the shaft is a constant speed.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an electric pump according to a first example embodiment of the present disclosure.

FIG. 2 is a plan view of an annular wall portion according to the first example embodiment as viewed from one side in an axial direction.

FIG. 3 is a plan view of a pump cover according to the first example embodiment as viewed from the other side in the axial direction.

FIG. 4 is a block diagram schematically illustrating a controller according to the first example embodiment.

FIG. 5 is a first diagram illustrating an example of a first variation value, a second variation value, and a third variation value in the electric pump according to the first example embodiment.

FIG. 6 is a second diagram illustrating an example of the first variation value, the second variation value, and the third variation value in the electric pump according to the first example embodiment.

FIG. 7 is a third diagram illustrating an example of the first variation value, the second variation value, and the third variation value in the electric pump according to the first example embodiment.

FIG. 8 is a flowchart illustrating an abnormality determination method for a sliding shaft supporting portion according to the first example embodiment.

FIG. 9 is a cross-sectional view illustrating an electric pump according to a modification of the first example embodiment.

FIG. 10 is a flowchart illustrating an abnormality determination method for an electric pump according to a second example embodiment of the present disclosure.

FIG. 11 is a first diagram illustrating an example of a rotational speed of a shaft in the electric pump according to the second example embodiment.

FIG. 12 is a second diagram illustrating an example of a rotational speed of a shaft in the electric pump according to the second example embodiment.

DETAILED DESCRIPTION

Electric pumps according to example embodiments of the present disclosure will be described with reference to the drawings. The scope of the present disclosure is not limited to the following example embodiments, and can be arbitrarily changed within the scope of the technical idea of the present disclosure. In the drawings described below, in order to make each configuration easy to understand, the scale, the number, and the like in each structure may be different from those in the actual structure.

In each drawing, an XYZ coordinate system is provided as appropriate. The direction in which the Y axis extends is the direction in which a rotation axis J of the example embodiment described below extends. The rotation axis J in each diagram is a virtual axis. In the following description, the direction in which the rotation axis J extends, that is, a direction parallel to the Y axis is referred to as an “axial direction”. A side in the axial direction toward which an arrow of the Y axis points (+Y side) is referred to as “one side in the axial direction” and a side in the axial direction opposite to the side toward which the arrow of the Y axis points (−Y side) is referred to as “other side in the axial direction”. A radial direction about the rotation axis J is simply referred to as a “radial direction”. A circumferential direction about the rotation axis J is simply referred to as a “circumferential direction”.

The direction in which the Z axis extends is an up-down direction in a state in which the electric pump of the example embodiment described below is attached. In the following description, the up-down direction in the state where the electric pump is attached is simply referred to as an “up-down direction”. In the up-down direction, a side (+Z side) to which an arrow of the Z axis points is referred to as an “upper side”.

The direction in which the X axis extends is a left-right direction in a state in which the electric pump of the example embodiment described below is attached. The left-right direction is a direction orthogonal to both the axial direction and the up-down direction. In the following description, the left-right direction in the state where the electric pump is attached is simply referred to as a “left-right direction”. A side in the left-right direction toward which an arrow of the X axis points (+X side) is referred to as “left side” and a side in the left-right direction opposite to the side toward which the arrow of the X axis points (−X side) is referred to as “right side”.

The posture of the electric pump with respect to the up-down direction described below is an example. Note that each of the upper side, the right side, and the left side are merely names for describing a relative relationship and the like of the respective parts, and an arrangement relationship and the like other than the arrangement relationship and the like indicated by these names may be employed.

First Example Embodiment

FIG. 1 is a cross-sectional view illustrating an electric pump 1 according to the present example embodiment. The electric pump 1 is attached to an attachment target device 5 installed in a vehicle, for example. In the present example embodiment, the electric pump 1 is accommodated inside an accommodating portion 5a of the attachment target device 5. The attachment target device 5 may be an automatic transmission or a drive device that drives an axle of a vehicle. The electric pump 1 of the present example embodiment is an electric pump that supplies a fluid R to the attachment target device 5. In the present example embodiment, the fluid R is oil. The fluid R may be another liquid such as water. The electric pump 1 is connected to a flow path provided in the attachment target device 5 via a suction port 19b and a discharge port 19c. The electric pump 1 includes a housing 10, a motor assembly 20, a pump assembly 40, and a controller 70.

The housing 10 has a substantially cylindrical shape extending in the axial direction. The housing 10 accommodates each of the motor assembly 20, the pump assembly 40, and the controller 70. The housing 10 includes a housing body portion 11, a lid portion 17, a pump cover 19, a motor accommodating portion 10a, and a pump accommodating portion 10c. In the present example embodiment, the housing body portion 11, the lid portion 17, and the pump cover 19 are separate members.

The housing body portion 11 has a substantially cylindrical shape that is centered on the rotation axis J, and extends in the axial direction. Each of the motor assembly 20 and the pump assembly 40 is accommodated inside the housing body portion 11. The housing body portion 11 includes a tubular portion 12, an annular wall portion 13, and a sliding shaft supporting portion 15. Thus, the housing 10 includes the sliding shaft supporting portion 15.

The tubular portion 12 has a substantially cylindrical shape that is centered on the rotation axis J, and extends in the axial direction. The tubular portion 12 is open on both sides, that is, on one side in the axial direction and on the other side in the axial direction. The tubular portion 12 surrounds each of the motor assembly 20 and the pump assembly 40 from the outer side in the radial direction. The lid portion 17 is fixed to an end portion of the tubular portion 12 on the other side in the axial direction. The pump cover 19 is fixed to an end portion of the tubular portion 12 on one side in the axial direction. The tubular portion 12 is provided with an engagement groove portion 12a and a recessed portion 12c. The tubular portion 12 includes a first inner surface portion 12e.

The engagement groove portion 12a is a groove recessed radially inward from the outer circumferential surface of the tubular portion 12. The engagement groove portion 12a is provided in a portion of the tubular portion 12 on the other side in the axial direction. The engagement groove portion 12a is provided along the outer circumferential surface of the tubular portion 12 over one round in the circumferential direction.

The recessed portion 12c is recessed toward the other side in the axial direction from a part of a surface of the tubular portion 12 facing the other side in the axial direction. The recessed portion 12c is provided in a right-side (-X side) portion of the surface of the tubular portion 12 facing the other side in the axial direction. The recessed portion 12c is open to each of the radially inner side and the radially outer side. Thus, a slight gap is provided between the housing body portion 11 and the lid portion 17. The internal space of the tubular portion 12 communicates with the external space of the housing 10 through the gap.

The first inner surface portion 12e is a portion of the inner surface of the tubular portion 12 more on one side in the axial direction than the annular wall portion 13. The first inner surface portion 12e surrounds the pump assembly 40 from the outer side in the radial direction. As viewed in the axial direction, the first inner surface portion 12e has a substantially circular shape eccentric with respect to the rotation axis J.

The annular wall portion 13 is disposed inside the tubular portion 12. The annular wall portion 13 is disposed more on one side in the axial direction than the motor assembly 20 and more on other side in the axial direction than the pump assembly 40. The annular wall portion 13 has a substantially annular shape centered on the rotation axis J. A portion of the outer circumferential surface of the annular wall portion 13 on one side in the axial direction is connected to the inner circumferential surface of the tubular portion 12 over one round in the circumferential direction. The annular wall portion 13 includes a facing surface 13a.

The facing surface 13a is a surface facing one side in the axial direction, of the outer surface of the annular wall portion 13. The facing surface 13a faces the pump assembly 40 in the axial direction. The facing surface 13a is provided with a first suction side groove portion 13c and a first discharge side groove portion 13e.

Each of the first suction side groove portion 13c and the first discharge side groove portion 13e is a groove recessed toward the other side in the axial direction from the facing surface 13a. Each of the first suction side groove portion 13c and the first discharge side groove portion 13e is open to one side in the axial direction. As illustrated in FIG. 2, each of the first suction side groove portion 13c and the first discharge side groove portion 13e is an arc-shaped groove extending in the circumferential direction. The first suction side groove portion 13c and the first discharge side groove portion 13e are provided at different positions in the circumferential direction. The first suction side groove portion 13c and the first discharge side groove portion 13e face each other in the radial direction, with the rotation axis J located therebetween.

As illustrated in FIG. 1, the sliding shaft supporting portion 15 is disposed inside the tubular portion 12. The sliding shaft supporting portion 15 is disposed more on one side in the axial direction than the motor assembly 20 and more on other side in the axial direction than the pump assembly 40 for example. The sliding shaft supporting portion 15 has a substantially cylindrical shape that is centered on the rotation axis J, and extends in the axial direction. An end portion of the sliding shaft supporting portion 15 on the other side in the axial direction is located more on the other side in the axial direction than the annular wall portion 13. In the axial direction, the position of the end portion of the sliding shaft supporting portion 15 on one side in the axial direction is substantially the same as the position of the facing surface 13a. A shaft 23 described below passes through the inside of the sliding shaft supporting portion 15 in the axial direction. As illustrated in FIG. 2, part of the outer circumferential surface of the sliding shaft supporting portion 15 is connected to the inner circumferential surface of the annular wall portion 13. The sliding shaft supporting portion 15 includes a support surface 15a and a first communication groove portion 15c.

The support surface 15a is an inner circumferential surface of the sliding shaft supporting portion 15. As viewed in the axial direction, the support surface 15a has a substantially circular shape. As illustrated in FIG. 1, the support surface 15a is in contact with the outer circumferential surface of the shaft 23 described below. The shaft 23 is supported by the support surface 15a so as to be rotatable about the rotation axis J. In the present example embodiment, the sliding shaft supporting portion 15 functions as a sliding bearing that supports the shaft 23.

The first communication groove portion 15c is a groove recessed toward the other side in the axial direction from a surface of the sliding shaft supporting portion 15 facing one side in the axial direction. The first communication groove portion 15c is provided in a right side (−X side) portion of the surface of the sliding shaft supporting portion 15 facing one side in the axial direction. As illustrated in FIG. 2, the first communication groove portion 15c extends linearly along the radial direction. The first communication groove portion 15c has the end portion, on the inner side in the radial direction, open to the inside of the sliding shaft supporting portion 15. The first communication groove portion 15c has the end portion, on the outer side in the radial direction, open to the first discharge side groove portion 13e. Thus, the first communication groove portion 15c connects the inside of the sliding shaft supporting portion 15 and the inside of the first discharge side groove portion 13e. Therefore, part of the fluid R supplied to the pump assembly 40 can be supplied between the shaft 23 and the support surface 15a, which will be described below, through the first discharge side groove portion 13e and the first communication groove portion 15c. Accordingly, the fluid R can be suitably interposed between the shaft 23 and the sliding shaft supporting portion 15. Therefore, the shaft 23 and the sliding shaft supporting portion 15 can be suitably lubricated by the fluid R.

As illustrated in FIG. 1, the lid portion 17 has a substantially cylindrical shape that is centered on the rotation axis J and protrudes in the axial direction. The lid portion 17 is open on one side in the axial direction. The lid portion 17 is fixed to an end portion of the housing body portion 11 on the other side in the axial direction. The lid portion 17 closes an opening of the tubular portion 12 on the other side in the axial direction. The internal space of the lid portion 17 and the internal space of the tubular portion 12 are connected to each other. The controller 70 is accommodated inside the lid portion 17. In the present example embodiment, the lid portion 17 is made of resin for example. The lid portion 17 may be made of another material such as a metal material. The lid portion 17 includes a circumferential wall portion 17a and a substrate cover 17e.

The circumferential wall portion 17a has a substantially annular shape that is centered on the rotation axis J. The circumferential wall portion 17a surrounds the controller 70 from the outer side in the radial direction. The circumferential wall portion 17a is provided with a plurality of claw portions 17b and a groove portion 17c.

Each of the plurality of claw portions 17b extends from the circumferential wall portion 17a toward one side in the axial direction. The claw portions 17b are arranged side by side along the circumferential direction. A protrusion portion protruding radially inward is provided at an end portion of each of the claw portions 17b on one side in the axial direction. The protrusion portion of each of the claw portions 17b is disposed inside the engagement groove portion 12a. Thus, the lid portion 17 is fixed to the housing body portion 11.

The groove portion 17c is a groove recessed radially inward from the outer circumferential surface of the circumferential wall portion 17a. The groove portion 17c extends along the outer circumferential surface of the circumferential wall portion 17a over one round in the circumferential direction. An O-ring 91 is fitted in the groove portion 17c. The O-ring 91 is in contact with the inner surface of the accommodating portion 5a of the attachment target device 5. Thus, the O-ring 91 seals between the housing 10 and the attachment target device 5.

The substrate cover 17e is disposed more on the other side in the axial direction than the circumferential wall portion 17a. The substrate cover 17e has a substantially disk shape centered on the rotation axis J. In the present example embodiment, the substrate cover 17e is adhesively fixed to the end portion of the circumferential wall portion 17a on the other side in the axial direction. The substrate cover 17e covers the controller 70 from the other side in the axial direction. Thus, the substrate cover 17e protects the controller 70.

The pump cover 19 has a substantially disk shape centered on the rotation axis J. The pump cover 19 is disposed more on one side in the axial direction than the pump assembly 40. The pump cover 19 covers the pump assembly 40 from one side in the axial direction. The pump cover 19 is fixed to the end portion of the housing body portion 11 on one side in the axial direction. The pump cover 19 closes the opening of the tubular portion 12 on one side in the axial direction. The pump cover 19 includes a suction portion 19a, the discharge port 19c, a second suction side groove portion 19e, a second discharge side groove portion 19f, a facing recess portion 19g, and a second communication groove portion 19j.

The suction portion 19a has a substantially circular columnar shape protruding from the pump cover 19 toward one side in the axial direction. The suction portion 19a is provided with the suction port 19b. The suction port 19b is provided on a distal end surface of the suction portion 19a. As described below, the suction port 19b is connected to the bottom surface of the second suction side groove portion 19e. The fluid R outside the electric pump 1 is sucked into the housing 10 through the suction port 19b.

The discharge port 19c is an opening provided in a surface of the pump cover 19 facing one side in the axial direction. The fluid R compressed in the pump assembly 40 is discharged to the outside of the electric pump 1 through the discharge port 19c.

Each of the second suction side groove portion 19e and the second discharge side groove portion 19f is a groove recessed toward one side in the axial direction from the surface of the pump cover 19 facing the other side in the axial direction. Each of the second suction side groove portion 19e and the second discharge side groove portion 19f is open to the other side in the axial direction. As illustrated in FIG. 3, each of the second suction side groove portion 19e and the second discharge side groove portion 19f is an arc-shaped groove extending in the circumferential direction. Each of the second suction side groove portion 19e and the second discharge side groove portion 19f is provided more on the outer side in the radial direction than the facing recess portion 19g. The second suction side groove portion 19e and the second discharge side groove portion 19f are provided at different positions in the circumferential direction. The second suction side groove portion 19e and the second discharge side groove portion 19f face each other in the radial direction, with the rotation axis J located therebetween.

The suction port 19b is open in the bottom surface of the second suction side groove portion 19e. Thus, the inside of the second suction side groove portion 19e is connected to the suction port 19b. As illustrated in FIG. 1, the second suction side groove portion 19e overlaps the first suction side groove portion 13c as viewed in the axial direction. As illustrated in FIGS. 2 and 3, the second suction side groove portion 19e and the first suction side groove portion 13c have substantially the same shape as viewed in the axial direction.

As illustrated in FIG. 3, the discharge port 19c is open in the bottom surface of the second discharge side groove portion 19f. Thus, the inside of the second suction side groove portion 19e is connected to the discharge port 19c. As illustrated in FIG. 1, the second discharge side groove portion 19f overlaps the first discharge side groove portion 13e as viewed in the axial direction. As illustrated in FIGS. 2 and 3, the second discharge side groove portion 19f and the first discharge side groove portion 13e have substantially the same shape as viewed in the axial direction.

As illustrated in FIG. 1, the facing recess portion 19g is a hole recessed toward one side in the axial direction, from a surface of the pump cover 19 facing the other side in the axial direction. As illustrated in FIG. 3, as viewed in the axial direction, the facing recess portion 19g is a substantially circular hole centered on the rotation axis J. The shape of the facing recess portion 19g is not limited to that in the present example embodiment. The facing recess portion 19g is provided more on the inner side in the radial direction than each of the second suction side groove portion 19e and the second discharge side groove portion 19f. As illustrated in FIG. 1, the facing recess portion 19g faces the shaft 23 described below in the axial direction.

The second communication groove portion 19j is a groove recessed toward one side in the axial direction from a surface of the pump cover 19 facing the other side in the axial direction. The second communication groove portion 19j is provided in a left side (+X side) portion of the surface of the pump cover 19 facing the other side in the axial direction. As illustrated in FIG. 3, the second communication groove portion 19j extends linearly along the radial direction. The second communication groove portion 19j has the end portion, on the inner side in the radial direction, open to the facing recess portion 19g. The second communication groove portion 19j has the end portion, on the outer side in the radial direction, open to the second suction side groove portion 19e. Thus, the inside of the facing recess portion 19g and the inside of the second suction side groove portion 19e are connected to each other through the second communication groove portion 19j. In the present example embodiment, the portion of the second suction side groove portion 19e connected to the suction port 19b is located more on the upper side (+Z side) than the portion connected to the second communication groove portion 19j.

As illustrated in FIG. 1, the motor accommodating portion 10a is a portion of the housing 10 that accommodates each of the motor assembly 20 and the controller 70. In the present example embodiment, the motor accommodating portion 10a includes a portion of the tubular portion 12 more on the other side in the axial direction than the annular wall portion 13, the annular wall portion 13, the sliding shaft supporting portion 15, and the lid portion 17. The pump accommodating portion 10c is a portion of the housing 10 that accommodates the pump assembly 40. In the present example embodiment, the pump accommodating portion 10c includes a portion of the tubular portion 12 more on one side in the axial direction than the annular wall portion 13, the annular wall portion 13, the sliding shaft supporting portion 15, and the pump cover 19. The pump accommodating portion 10c is located more on one side in the axial direction than the motor accommodating portion 10a. The pump accommodating portion 10c and the motor accommodating portion 10a are separated from each other by the annular wall portion 13 and the sliding shaft supporting portion 15.

The motor assembly 20 is accommodated inside the housing body portion 11. More specifically, the motor assembly 20 is accommodated inside the motor accommodating portion 10a. In the axial direction, the motor assembly 20 is disposed more on one side in the axial direction than the controller 70 and more on the other side in the axial direction than the pump assembly 40. The motor assembly 20 includes a rotor 21, a stator 30, and a terminal unit 38.

The rotor 21 is rotatable about the rotation axis J. The rotor 21 includes a rotor core 21a, a magnet 21b, and the shaft 23. Thus, the motor assembly 20 includes the shaft 23. The rotor core 21a has a substantially annular shape centered on the rotation axis J. The magnet 21b is fixed to the rotor core 21a.

The shaft 23 has a substantially cylindrical shape that is centered on the rotation axis J and extends in the axial direction. In the present example embodiment, the shaft 23 is a hollow shaft. The shaft 23 extends across the motor accommodating portion 10a and the pump accommodating portion 10c. An end portion of the shaft 23 on the other side in the axial direction is disposed inside the motor accommodating portion 10a. An end portion of the shaft 23 on one side in the axial direction is disposed inside the pump accommodating portion 10c. The shaft 23 passes through each of the inside of the rotor core 21a and the inside of the sliding shaft supporting portion 15 in the axial direction. A portion of the shaft 23 on the other side in the axial direction is fixed to the inner circumferential surface of the rotor core 21a. Thus, the shaft 23 is rotatable about the rotation axis J. A portion of the shaft 23 on a center side in the axial direction is supported by the support surface 15a of the sliding shaft supporting portion 15 to be rotatable about the rotation axis J. Thus, the sliding shaft supporting portion 15 supports the shaft 23. An end portion of the shaft 23 on one side in the axial direction is coupled to the pump assembly 40. Thus, the rotational torque of the rotor 21 is transmitted to the pump assembly 40. The shaft 23 includes a hollow portion 23h. The hollow portion 23h is open on both sides, that is, on one side in the axial direction and on the other side in the axial direction. Thus, the inside of the motor accommodating portion 10a and the inside of the facing recess portion 19g are connected to each other through the hollow portion 23h.

The stator 30 is disposed more on the outer side in the radial direction than the rotor 21. The stator 30 faces the rotor 21 in the radial direction with a gap in between. The stator 30 includes a stator core 31, an insulator 32, and a coil portion 33.

The stator core 31 surrounds the rotor core 21a from the outer side in the radial direction. The outer circumferential surface of the stator core 31 is fixed to the inner circumferential surface of the tubular portion 12. The stator core 31 includes a core back portion 31a having a substantially annular shape, and a plurality of teeth portions 31b protruding radially inward from an inner circumferential surface of the core back portion 31a. Although not illustrated, the plurality of teeth portions 31b are arranged while being separated from each other in the circumferential direction. The coil portion 33 is wound around the teeth portions 31b via the insulator 32.

The coil portion 33 is formed of a wound coil wire. As illustrated in FIG. 4, the coil portion 33 includes a U-phase coil 33U, a V-phase coil 33V, and a W-phase coil 33W. The controller 70 supplies different phase currents (U-phase current, V-phase current, and W-phase current) to the U-phase coil 33U, the V-phase coil 33V, and the W-phase coil 33W, respectively. A coil wire (not illustrated) is drawn out from the coil portion 33.

Although not illustrated, the coil wire drawn out from the coil portion 33 is connected to the terminal unit 38 illustrated in FIG. 1. The terminal unit 38 is disposed between the stator 30 and the controller 70 in the axial direction. The terminal unit 38 includes a plurality of terminals. The plurality of terminals include a U-phase terminal 39U, a V-phase terminal 39V, and a W-phase terminal 39W illustrated in FIG. 4. The terminal unit 38 electrically connects the coil portion 33 and the controller 70 via the plurality of terminals 39U, 39V, and 39W.

As illustrated in FIG. 1, the pump assembly 40 is accommodated inside the housing body portion 11. More specifically, the pump assembly 40 is accommodated inside the pump accommodating portion 10c. The pump assembly 40 is disposed more on one side in the axial direction than the motor assembly 20. The pump assembly 40 is coupled to the end portion of the shaft 23 on one side in the axial direction. The pump assembly 40 is driven by the power from the motor assembly 20 to suck the fluid R from the outside of the electric pump 1, and compresses the sucked fluid R to discharge the fluid R to the outside of the electric pump 1. The pump assembly 40 is driven by the power from the motor assembly 20 to pump the fluid R. The pump assembly 40 of the present example embodiment is a trochoid pump. The pump assembly 40 includes an inner rotor 41 and an outer rotor 42.

The inner rotor 41 has an annular shape extending in the axial direction A. A portion of the shaft 23 on one side in the axial direction is inserted in the inner rotor 41. The shaft 23 is fixed to the inner circumferential surface of the inner rotor 41. Thus, the pump assembly 40 is coupled to the end portion of the shaft 23 on one side in the axial direction. The power from the rotor 21 is transmitted to the inner rotor 41. Thus, the inner rotor 41 can be rotated about the rotation axis J.

The outer rotor 42 is disposed more on the outer side in the radial direction than the inner rotor 41. The outer rotor 42 has an annular shape to surround the inner rotor 41 from the outer side in the radial direction. The outer circumferential surface of the outer rotor 42 is in contact with the first inner surface portion 12e in the radial direction. The outer rotor 42 is supported by the first inner surface portion 12e to be rotatable about the rotation axis J.

Each of the inner rotor 41 and the outer rotor 42 includes a trochoidal tooth profile (not illustrated). The trochoidal tooth profile of the inner rotor 41 and the trochoidal tooth profile of the outer rotor 42 mesh with each other at one location in the circumferential direction. When the inner rotor 41 rotates integrally with the shaft 23 about the rotation axis J, the outer rotor 42 eccentrically rotates about the rotation axis J while sliding on the first inner surface portion 12e.

The inside of the second suction side groove portion 19e and the inside of the first suction side groove portion 13c are connected in the axial direction via a gap G between the inner rotor 41 and the outer rotor 42. In the following description, the internal space of the second suction side groove portion 19e and the internal space of the first suction side groove portion 13c, which are connected to each other, are referred to as a suction chamber A2. The suction chamber A2 is connected to the suction port 19b.

The inside of the second discharge side groove portion 19f and the inside of the first discharge side groove portion 13e are connected in the axial direction via the gap G between the inner rotor 41 and the outer rotor 42. In the following description, the internal space of the second discharge side groove portion 19f and the internal space of the first discharge side groove portion 13e, which are connected to each other, are referred to as a compression chamber A1. The compression chamber A1 is connected to the discharge port 19c.

When the electric pump 1 is driven, the gap G between the inner rotor 41 and the outer rotor 42 moves around the rotation axis J. When the pressure of the suction chamber A2 thus drops, the fluid R flows into the suction chamber A2 via the suction port 19b as indicated by an arrow F1 in FIG. 1. When the gap G moves further in the circumferential direction, the fluid R moves from the suction chamber A2 to the compression chamber A1 as indicated by the arrow F2 in FIG. 1. When the pressure of the compression chamber A1 thus rises, the fluid R in the compression chamber A1 is pumped to the outside of the electric pump 1 via the discharge port 19c as indicated by an arrow F3 in FIG. 1. The fluid R pumped into the accommodating portion 5a of the attachment target device 5 is pumped into a flow path (not illustrated) in the attachment target device 5 via an opening portion 5b provided in the attachment target device 5. With such configurations, the electric pump 1 supplies the fluid R to the attachment target device 5.

As described above, the first communication groove portion 15c connects the inside of the sliding shaft supporting portion 15 and the inside of the first discharge side groove portion 13e. That is, the first communication groove portion 15c connects the inside of the sliding shaft supporting portion 15 and the compression chamber A1. When the pressure in the compression chamber A1 rises as described above while the electric pump 1 is driven, part of the fluid R in the compression chamber A1 flows into the motor accommodating portion 10a through the first communication groove portion 15c and the inside of the sliding shaft supporting portion 15 as indicated by an arrow F4 in FIG. 1. Accordingly, the fluid R is supplied to the inside of the motor accommodating portion 10a, and the fluid R is supplied between the shaft 23 and the support surface 15a. Thus, the pump assembly 40 supplies the fluid R to the sliding shaft supporting portion 15. Thus, the fluid R can be suitably interposed between the shaft 23 and the sliding shaft supporting portion 15. Accordingly, the shaft 23 and the sliding shaft supporting portion 15 can be suitably lubricated by the fluid R, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 can be reduced. Therefore, a rotational speed Rv of the shaft 23 can be stabilized. In the following description, the “rotational speed Rv of the shaft 23” may be simply referred to as a “rotational speed Rv”. The rotational speed Rv of the shaft 23 is the same as the rotational speed of the rotor 21.

As indicated by an arrow F5 in FIG. 1, part of the fluid R pumped into the accommodating portion 5a of the attachment target device 5 flows into the motor accommodating portion 10a via the recessed portion 12c provided in the tubular portion 12. Accordingly, the fluid R is supplied to the inside of the motor accommodating portion 10a. As described above, part of the fluid R in the compression chamber A1 flows into the motor accommodating portion 10a through the first communication groove portion 15c and the inside of the sliding shaft supporting portion 15. Accordingly, the fluid R is stored inside the motor accommodating portion 10a. The rotation of the rotor 21 causes the fluid R in the motor accommodating portion 10a to circulate inside the motor accommodating portion 10a, and cool each of the motor assembly 20 and the controller 70. As a result, excessive rise in temperature of each of the motor assembly 20 and the controller 70 can be suppressed, whereby the motor assembly 20 and the controller 70 can operate with improved stability.

As described above, the inside of the motor accommodating portion 10a and the inside of the facing recess portion 19g provided to the pump cover 19 are connected to each other via the hollow portion 23h of the shaft 23. As described above, the inside of the facing recess portion 19g and the inside of the second suction side groove portion 19e are connected to each other via the second communication groove portion 19j. With such configurations, the inside of the motor accommodating portion 10a is connected to the suction chamber A2. Therefore, as described above, when the pressure of the suction chamber A2 drops during the driving of the electric pump 1, as indicated by an arrow F6 in FIG. 1, part of the fluid R inside the motor accommodating portion 10a flows into the suction chamber A2 via the hollow portion 23h, the facing recess portion 19g, and the second communication groove portion 19j. The fluid R that has flowed into the suction chamber A2 is pumped from the discharge port 19c to the outside of the electric pump 1 together with the fluid R that has flowed into the suction chamber A2 from the suction port 19b.

As described above, the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15 lubricates the shaft 23 and the sliding shaft supporting portion 15. Therefore, when the shaft 23 continues to rotate in a state where the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15 is small, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases, and at least one of the shaft 23 or the sliding shaft supporting portion 15 wears. When abrasion powder of at least one of the shaft 23 or the sliding shaft supporting portion 15 is caught between the inner rotor 41 and the outer rotor 42, the pump assembly 40 may be locked. Further, when the wear amount of the sliding shaft supporting portion 15 increases, an axial inclination of the shaft 23 may occur. Accordingly, when the axial inclination of the inner rotor 41 occurs, a frictional force may increase between the inner circumferential surface of the pump accommodating portion 10c and the outer rotor 42. When a gap is produced between the pump accommodating portion 10c and the outer rotor 42 due to the wear of the inner circumferential surface of the pump accommodating portion 10c, the pressure of the fluid R in the compression chamber A1 drops, and the pump efficiency may be decreased. In the following description, the wearing of at least one of the shaft 23 or the sliding shaft supporting portion 15, the locking of the pump assembly 40, and the decreased pump efficiency may be referred to as a failure of the electric pump 1.

The controller 70 controls the current supplied to the coil portion 33 of the stator 30 based on a control signal transmitted from a main body control unit 6 in a vehicle or the like, an operation of each part of the electric pump 1, a current supplied to each unit of the electric pump 1, and the like. Thus, the controller 70 controls the operation of the motor assembly 20. That is, the controller 70 controls the operation of the electric pump 1. The main body control unit 6 is, for example, an in-vehicle electronic control unit (ECU) installed in a vehicle. As illustrated in FIG. 1, the controller 70 is disposed more on the other side in the axial direction than the motor assembly 20. As described above, the controller 70 is electrically connected to the motor assembly 20 via the terminal unit 38. The controller 70 includes a circuit board 71. As illustrated in FIG. 4, the controller 70 includes a motor drive circuit 72, a control unit 75, a storage unit 76, a first detection unit 77, a second detection unit 78, and a third detection unit 79.

As illustrated in FIG. 1, the circuit board 71 has a plate shape spreading in a direction orthogonal to the axial direction. The circuit board 71 is electrically connected to the coil portion 33 of the stator 30 via the terminal unit 38. As illustrated in FIG. 4, the motor drive circuit 72, the control unit 75, the storage unit 76, the first detection unit 77, the second detection unit 78, and the third detection unit 79 are each mounted on the circuit board 71.

The motor drive circuit 72 is a circuit that supplies current to the motor assembly 20. The motor drive circuit 72 converts a direct current supplied from an external power supply 95 into a three-phase alternating current and supplies the three-phase alternating current to the motor assembly 20. In the present example embodiment, the external power supply 95 is, for example, a battery installed in the vehicle. The motor drive circuit 72 includes a U-phase upper arm switch Q_UH, a V-phase upper arm switch Q_VH, a W-phase upper arm switch Q_WH, a U-phase lower arm switch Q_UL, a V-phase lower arm switch Q_VL, and a W-phase lower arm switch Q_WL. In the present example embodiment, each of the arm switches is, for example, an N-channel MOS-FET.

Each of the drain terminal of the U-phase upper arm switch Q_UH, the drain terminal of the V-phase upper arm switch Q_VH, and the drain terminal of the W-phase upper arm switch Q_WH is electrically connected to the positive terminal of the external power supply 95. Each of the source terminal of the U-phase lower arm switch Q_UL, the source terminal of the V-phase lower arm switch Q_VL, and the source terminal of the W-phase lower arm switch Q_WL is electrically connected to the negative terminal of the external power supply 95 via the second detection unit 78. The negative terminal of the external power supply 95 is grounded.

The source terminal of the U-phase upper arm switch Q_UH is electrically connected to the drain terminal of the U-phase lower arm switch Q_UL, and is electrically connected to the U-phase terminal 39U via a U-phase connection line 35U. The source terminal of the V-phase upper arm switch Q_VH is electrically connected to the drain terminal of the V-phase lower arm switch Q_VL, and is electrically connected to the V-phase terminal 39V via a V-phase connection line 35V. The source terminal of the W-phase upper arm switch Q_WH is electrically connected to the drain terminal of the W-phase lower arm switch Q_WL, and is electrically connected to the W-phase terminal 39W via a W-phase connection line 35W.

The gate terminal of the U-phase upper arm switch Q_UH, the gate terminal of the V-phase upper arm switch Q_VH, and the gate terminal of the W-phase upper arm switch Q_WH are each electrically connected to the control unit 75. The gate terminal of the U-phase lower arm switch Q_UL, the gate terminal of the V-phase lower arm switch Q_VL, and the gate terminal of the W-phase lower arm switch Q_WL are also each electrically connected to the control unit 75.

The motor drive circuit 72 of the present example embodiment is an inverter configured by a three-phase full-bridge circuit having three upper arm switches and three lower arm switches. The motor drive circuit 72 converts a direct current supplied from the external power supply 95 into a three-phase alternating voltage and supplies the alternating voltage to each of the coils 33U, 33V, and 33W of the respective phases, through switching control on each of the arm switches by the control unit 75.

The first detection unit 77 detects the voltage applied to the coils 33U, 33V, and 33W of the respective phases, and inputs the detection result to the control unit 75. In the present example embodiment, the controller 70 includes three first detection units 77. One ends of the first detection units 77 are respectively electrically connected to the connection lines 35U, 35V, and 35W different from each other. The other end of each first detection unit 77 is grounded. Although not illustrated, each of the first detection units 77 is electrically connected to the control unit 75. The control unit 75 calculates the rotational speed Rv of the shaft 23 based on the counter electromotive voltage produced in the coil, among the U-phase coil 33U, the V-phase coil 33V, and the W-phase coil 33W, to which the current is not supplied from the motor drive circuit 72.

The second detection unit 78 detects the current supplied to the motor assembly 20, and inputs a current value Im, as the detection result, to the control unit 75. In the present example embodiment, the second detection unit 78 is, for example, a shunt resistor. One end of the second detection unit 78 is electrically connected to the source terminal of each of the three lower arm switches. The other end of the second detection unit 78 is electrically connected to the negative terminal of the external power supply 95. One end of the second detection unit 78 is electrically connected to the control unit 75. A voltage proportional to the current supplied to the motor assembly 20 appears between the terminals of the second detection unit 78. The voltage between the terminals of the second detection unit 78 is input to the control unit 75 as the current value Im indicating the current supplied to the motor assembly 20.

The third detection unit 79 detects a voltage applied to the controller 70, and inputs a voltage value Vc, which is the detection result, to the control unit 75. One end of the third detection unit 79 is electrically connected to the positive terminal of the external power supply 95. The other end of the third detection unit 79 is electrically connected to the negative terminal of the external power supply 95. Although not illustrated, the third detection unit 79 is electrically connected to the control unit 75.

The control unit 75 is a microprocessor such as a microcontroller unit (MCU) for example. A rotational speed command signal CS1 is input to the control unit 75 from the main body control unit 6. The control unit 75 calculates a target rotational speed TRv of the shaft 23 based on the rotational speed command signal CS1. In the following description, the target rotational speed TRv of the shaft 23 may be simply referred to as “target rotational speed TRv”. As described below, upon determining an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15, the control unit 75 transmits an abnormality determination signal Sa to the main body control unit 6. In the following description, the abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 may be simply referred to as an “abnormality of the sliding shaft supporting portion”. The main body control unit 6 transmits a rotation time command signal CS2 to the control unit 75 based on the abnormality determination signal Sa. The control unit 75 calculates a second predetermined period P2 since the abnormality of the sliding shaft supporting portion 15 is determined until the operation of the motor assembly 20 stops, based on the rotation time command signal CS2. In the present example embodiment, the second predetermined period P2 is, for example, 10 seconds or less.

As described above, the counter electromotive voltage generated in the coil to which the current is not supplied from the motor drive circuit 72 is input to the control unit 75 from the first detection unit 77. The control unit 75 calculates the rotational speed Rv based on such counter electromotive voltage. The control unit 75 controls the rotational speed Rv by controlling the motor drive circuit 72 based on the rotational speed Rv and the target rotational speed TRv. Specifically, the control unit 75 determines a switching duty ratio of each arm switch required to make the rotational speed Rv match the target rotational speed TRv, and performs switching control for each arm switch at the determined switching duty ratio. As a result, the three-phase alternating current that makes the rotational speed Rv match the target rotational speed TRv is supplied to the motor assembly 20. That is, the controller 70 controls the current supplied to the motor assembly 20 to make the rotational speed Rv of the shaft 23 match the target rotational speed TRv.

As described above, the current value Im, which is the current supplied to the motor assembly 20, is input to the control unit 75 from the second detection unit 78. As described above, the voltage value Vc, which is the voltage applied to the controller 70, is input to the control unit 75 from the third detection unit 79. With such configurations, the controller 70 acquires each of the rotational speed Rv, the current value Im, and the voltage value Vc.

FIG. 5 is a first diagram illustrating an example of a first variation value Vf1, a second variation value Vf2, and a third variation value Vf3 in the electric pump 1 of the present example embodiment. The uppermost graph in FIG. 5 indicates the transition of a fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15. In the present example embodiment, a case will be described where the fluid amount MR is stabilized at a sufficient amount from a time point T0 to a time point T3 and the fluid amount MR monotonously decreases from and after the time point T3. The decrease in the fluid amount MR occurs when the amount of the fluid R supplied from the pump assembly 40 to the sliding shaft supporting portion 15 decreases due to, for example, clogging of the first communication groove portion 15c (see FIG. 1) with foreign matter. When the fluid amount MR decreases, the shaft 23 and the support surface 15a are likely to come into direct contact with each other, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases.

The second graph from the top in FIG. 5 indicates the transition of the rotational speed Rv of the shaft 23 calculated by the control unit 75. The rotational speed Rv has an amplitude from the target rotational speed TRv. In the present example embodiment, a variation value of the rotational speed Rv of the shaft 23 in a first predetermined period P1 is referred to as the first variation value Vf1. The controller 70 calculates the first variation value Vf1 based on the rotational speed Rv. The first variation value Vf1 is correlated with the rotational speed Rv of the shaft 23, that is, the target rotational speed TRv. From the time point T0 to the time point T3 with the fluid amount MR being stable at a sufficient amount, the shaft 23 and the sliding shaft supporting portion 15 can be suitably lubricated by the fluid R, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 can be reduced. As a result, the rotational speed Rv of the shaft 23 is stabilized, and thus the first variation value Vf1 is small. On the other hand, from and after the time point T3 at which the fluid amount MR decreases, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases as described above. As a result, the rotational speed Rv is unstable from and after the time point T3, and the amplitude of the rotational speed Rv increases. Thus, when the fluid amount MR decreases, the first variation value Vf1 increases. Therefore, the controller 70 can determine an abnormality of the sliding shaft supporting portion 15 based on the first variation value Vf1.

When the control unit 75 determines an abnormality of the sliding shaft supporting portion 15 based on the first variation value Vf1, the target rotational speed TRv in the first predetermined period P1 is preferably a constant speed. This prevents the first variation value Vf1 from including a variation in the rotational speed Rv caused by adjusting the target rotational speed TRv to a different speed. Therefore, the control unit 75 can accurately determine an abnormality of the sliding shaft supporting portion 15 based on the first variation value Vf1.

The first predetermined period P1 is preferably 1 second or more and 3 seconds or less. This prevents the first predetermined period P1 from being too long, and thus an abnormality of the sliding shaft supporting portion 15 can be quickly determined. In the present example embodiment, the first predetermined period P1 is two seconds. The first predetermined period P1 may be shorter than two seconds or longer than two seconds as long as the abnormality of the sliding shaft supporting portion 15 can be quickly determined.

The third graph from the top in FIG. 5 indicates the transition of the current value Im indicating the current supplied to the motor assembly 20. In the present example embodiment, the variation value of the current value Im in the first predetermined period P1 is referred to as the second variation value Vf2. The controller 70 calculates the second variation value Vf2 based on the current value Im. The second variation value Vf2 is small from the time point T0 to the time point T3 with the fluid amount MR being stable at a sufficient amount. This is because the rotational speed Rv of the shaft 23 is stable as described above. That is, the second variation value Vf2 is correlated with the rotational speed Rv of the shaft 23, that is, the target rotational speed TRv. On the other hand, the second variation value Vf2 increases from and after the time point T3 where the fluid amount MR decreases. This is because the rotational speed Rv is unstable when the fluid amount MR decreases as described above. Thus, when the fluid amount MR decreases, the second variation value Vf2 increases. Therefore, the controller 70 can determine an abnormality of the sliding shaft supporting portion 15 based on the second variation value Vf2.

The lowermost graph in FIG. 5 indicates the transition of the voltage value Vc indicating the voltage applied to the controller 70. In the present example embodiment, the variation value of the voltage value Vc in the first predetermined period P1 is referred to as the third variation value Vf3. The controller 70 calculates the third variation value Vf3 based on the voltage value Vc. The third variation value Vf3 is small from the time point T0 to the time point T3 when the fluid amount MR is stable at a sufficient amount. This is because the rotational speed Rv of the shaft 23 is stable as described above. That is, the third variation value Vf3 is correlated with the rotational speed Rv of the shaft 23, that is, the target rotational speed TRv. On the other hand, the third variation value Vf3 increases from and after the time point T3 where the fluid amount MR decreases. This is because the rotational speed Rv is unstable when the fluid amount MR decreases as described above. Thus, when the fluid amount MR decreases, the third variation value Vf3 increases. Therefore, the controller 70 can determine an abnormality of the sliding shaft supporting portion 15 based on the third variation value Vf3.

As illustrated in FIG. 4, the control unit 75 includes a determinator 75a. Thus, the controller 70 includes the determinator 75a. In the present example embodiment, the determinator 75a is a part of the control unit 75. In the present example embodiment, the determinator 75a determines a first determination value Vj1, a second determination value Vj2, and a third determination value Vj3 based on the target rotational speed TRv. The first determination value Vj1 is a threshold for the first variation value Vf1 for the controller 70 to determine an abnormality of the sliding shaft supporting portion 15. In the present example embodiment, when the first variation value Vf1 is less than the first determination value Vj1, the controller 70 determines that no abnormality is occurring in the sliding shaft supporting portion 15, and continues the operation of the motor assembly 20. On the other hand, as illustrated in FIG. 5, when the first variation value Vf1 is equal to or larger than the first determination value Vj1, the controller 70 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15.

The second determination value Vj2 is a threshold for the second variation value Vf2, for the controller 70 to determine an abnormality of the sliding shaft supporting portion 15. In the present example embodiment, when the second variation value Vf2 is less than the second determination value Vj2, the controller 70 determines that no abnormality is occurring in the sliding shaft supporting portion 15, and continues the operation of the motor assembly 20. FIG. 6 is a second diagram illustrating an example of the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 in the electric pump 1 of the present example embodiment. As illustrated in FIG. 6, when the second variation value Vf2 is equal to or larger than the second determination value Vj2, the controller 70 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15.

The third determination value Vj3 is a threshold for the third variation value Vf3, for the controller 70 to determine an abnormality of the sliding shaft supporting portion 15. In the present example embodiment, when the third variation value Vf3 is less than the third determination value Vj3, the controller 70 determines that no abnormality is occurring in the sliding shaft supporting portion 15, and continues the operation of the motor assembly 20. FIG. 7 is a third diagram illustrating an example of the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 in the electric pump 1 of the present example embodiment. As illustrated in FIG. 7, when the third variation value Vf3 is equal to or larger than the third determination value Vj3, the controller 70 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15.

The storage unit 76 includes a nonvolatile memory that stores programs, various pieces of setting data, and the like necessary for the control unit 75 to execute various processes, and a volatile memory that is used as a temporary storage for data when the control unit 75 executes various processes. The nonvolatile memory is, for example, an electrically erasable programmable read-only memory (EEPROM), a flash memory, or the like. The volatile memory is, for example, a random access memory (RAM) or the like. The storage unit 76 may be provided outside the control unit 75 or may be built in the control unit 75. The storage unit 76 is communicably connected to the control unit 75 via a communication bus (not illustrated). The control unit 75 executes an abnormality determination for at least the sliding shaft supporting portion 15 according to a program stored in advance in the storage unit 76.

FIG. 8 is a flowchart illustrating an abnormality determination method for the sliding shaft supporting portion 15 according to the present example embodiment. The abnormality determination method for the sliding shaft supporting portion 15 according to the present example embodiment is a method for determining an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15. When the controller 70 starts the operation of the motor assembly 20, the determinator 75a determines the first determination value Vj1, the second determination value Vj2, and the third determination value Vj3 based on the target rotational speed TRv (S01). In the present example embodiment, the determinator 75a determines the first determination value Vj1, the second determination value Vj2, and the third determination value Vj3 based on the target rotational speed TRv each time the target rotational speed TRv is changed.

Next, as described above, the controller 70 calculates the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 in the first predetermined period P1 in which the target rotational speed TRv of the shaft 23 is a constant speed based on the target rotational speed TRv (S02).

Next, when the first variation value Vf1 is less than the first determination value Vj1 (S03), the second variation value Vf2 is less than the second determination value Vj2 (S04), and the third variation value Vf3 is less than the third determination value Vj3 (S05), the controller 70 determines that the fluid amount MR is sufficient, and continues the operation of the motor assembly 20. Thereafter, the controller 70 repeats the above-described operation.

On the other hand, when the first variation value Vf1 is equal to or larger than the first determination value Vj1 (S03), when the second variation value Vf2 is equal to or larger than the second determination value Vj2 (S04), or when the third variation value Vf3 is equal to or larger than the third determination value Vj3 (S05), the controller 70 determines that there is an abnormality in the sliding shaft supporting portion 15, and transmits the abnormality determination signal Sa to the main body control unit 6 (S06) (see FIG. 4). The controller 70 may determine the abnormality of the sliding shaft supporting portion 15 based on, for example, the absolute value of each of the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3. Also in this case, the controller 70 can accurately determine the abnormality of the sliding shaft supporting portion 15. In this case, the determinator 75a may or may not determine each of the first determination value Vj1, the second determination value Vj2, and the third determination value Vj3.

The timing at which the controller 70 transmits the abnormality determination signal Sa to the main body control unit 6 may employ various timings as will be described below. For example, as illustrated in FIG. 5, the controller 70 may start calculating the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 at a time point T4, and when the first variation value Vf1 is equal to or larger than the first determination value Vj1 at a time point Tj, may transmit the abnormality determination signal Sa to the main body control unit 6 at a time point T5, which is a timing when the first predetermined period P1 has elapsed from the time point T4. As illustrated in FIG. 6, the controller 70 may start calculating the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 at the time point T4, and immediately transmit the abnormality determination signal Sa to the main body control unit 6 when the second variation value Vf2 is equal to or larger than the second determination value Vj2 at the time point Tj. Similarly, also in FIG. 7, the controller 70 starts calculating the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 at the time point T4, and immediately transmits the abnormality determination signal Sa to the main body control unit 6 when the third variation value Vf3 is equal to or larger than the third determination value Vj3 at the time point Tj.

When the controller 70 transmits the abnormality determination signal Sa to the main body control unit 6, the main body control unit 6 transmits the rotation time command signal CS2 to the control unit 75 as described above. The control unit 75 calculates the second predetermined period P2 since the abnormality of the sliding shaft supporting portion 15 is determined until the operation of the motor assembly 20 stops, based on the rotation time command signal CS2. For the rotation time command signal CS2 input to the controller 70 by the main body control unit 6, various modes can be employed as described below. For example, the rotation time command signal CS2 may be a command signal for immediately stopping the operation of the motor assembly 20, that is, the second predetermined period P2 may be 0 seconds. In this case, as illustrated in FIG. 5, when the rotation time command signal CS2 is received at the time point T5, the controller 70 quickly stops the supply of the current to the motor assembly 20 and the operation of the motor assembly 20 (S07). Similarly, in a case where the rotation time command signal CS2 is a command signal with the second predetermined period P2 being 0 seconds, as illustrated in FIG. 6, when the rotation time command signal CS2 is received at the time point Tj, the controller 70 quickly stops the supply of the current to the motor assembly 20 and the operation of the motor assembly 20 (S07). In these cases, when the controller 70 determines an abnormality of the sliding shaft supporting portion 15, the operation of the motor assembly 20 can be stopped quickly, and thus the shaft 23 can be suitably prevented from rotating in a state where the fluid amount MR between the shaft 23 and the sliding shaft supporting portion 15 is small. Thus, the electric pump 1 can be suitably prevented from failing.

The rotation time command signal CS2 may be a command signal for stopping the operation of the motor assembly 20 after the operation of the motor assembly 20 has been continued for the second predetermined period P2 after the controller 70 determines the abnormality of the sliding shaft supporting portion 15. In this case, as illustrated in FIG. 7, upon receiving the rotation time command signal CS2 at the time point Tj, the controller 70 stops the operation of the motor assembly 20 at a time point T6 after the elapse of the second predetermined period P2 from the time point Tj (S07). That is, the controller 70 stops the operation of the motor assembly 20 when the second predetermined period P2 elapses after the determination of the abnormality of the sliding shaft supporting portion 15 at the time point Tj. Accordingly, the operation of the motor assembly 20 can be stopped after the fluid R of an amount required by the attachment target device 5 is supplied to the attachment target device 5. Thus, the operation of the attachment target device 5 can be prevented from being unstable.

Further, as illustrated in FIG. 7, the controller 70 may set the rotational speed Rv of the shaft 23 in the second predetermined period P2 to a low rotational speed. That is, upon determining the abnormality of the sliding shaft supporting portion 15, the controller 70 may lower the rotational speed Rv of the shaft 23. Accordingly, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 in the second predetermined period P2 can be reduced, and thus, the electric pump 1 can be suitably prevented from failing in the second predetermined period P2.

When the operation of the motor assembly 20 is stopped after the abnormality of the sliding shaft supporting portion 15 is determined, an operator who performs maintenance or the like of the electric pump 1 can recover the amount of the fluid R supplied from the pump assembly 40 to the sliding shaft supporting portion 15 to a normal amount by performing an operation such as removing a foreign matter clogging the first communication groove portion 15c (see FIG. 1) for example. Accordingly, during the operation of the electric pump 1, the fluid amount MR interposed between the shaft 23 and the sliding shaft supporting portion 15 can be set to an appropriate amount, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 can be reduced. Thus, the electric pump 1 can be prevented from failing.

According to the present example embodiment, the electric pump 1 includes the motor assembly 20 including the shaft 23 rotatable about the rotation axis J, the pump assembly 40 coupled to the end portion of the shaft 23 on one side in the axial direction and driven by the power from the motor assembly 20 to pump the fluid R, the housing 10 configured to accommodate the motor assembly 20 and the pump assembly 40, and the controller 70 configured to control the operation of the motor assembly 20. The housing 10 includes the motor accommodating portion 10a configured to accommodate the motor assembly 20, the pump accommodating portion 10c configured to accommodate the pump assembly 40, and the sliding shaft supporting portion 15 configured to support the shaft 23, the fluid R is interposed between the shaft 23 and the sliding shaft supporting portion 15, and the controller 70 determines an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 based on the first variation value Vf1 which is a variation value of the rotational speed Rv of the shaft 23, the second variation value Vf2 which is a variation value of the current supplied to the motor assembly 20, or the third variation value Vf3 which is a variation value of the voltage applied to the controller 70 in the first predetermined period P1 in which the target rotational speed TRv of the shaft 23 is a constant speed. As described above, when the fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15, decreases, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases, and thus the rotational speed Rv of the shaft 23 is unstable. Thus, when the fluid amount MR decreases, the first variation value Vf1 increases. As described above, the controller 70 controls the current supplied to the motor assembly 20 to make the rotational speed Rv of the shaft 23 match the target rotational speed TRv. Therefore, when the rotational speed Rv of the shaft 23 is unstable, each of the second variation value Vf2 and the third variation value Vf3 increases. Thus, the controller 70 can determine that an abnormality has occurred in the sliding shaft supporting portion 15 based on the first variation value Vf1, the second variation value Vf2, or the third variation value Vf3. Further, when an abnormality occurs in the sliding shaft supporting portion 15, the controller 70 can quickly stop the operation of the motor assembly 20, and thus can suitably prevent the electric pump 1 from failing.

According to the present example embodiment, the controller 70 includes the determinator 75a configured to determine the first determination value Vj1, the second determination value Vj2, and the third determination value Vj3 based on the target rotational speed TRv, and the controller 70 determines an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 when the first variation value Vf1 is equal to or larger than the first determination value Vj1, when the second variation value Vf2 is equal to or larger than the second determination value Vj2, or when the third variation value Vf3 is equal to or larger than the third determination value Vj3. As described above, each of the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 is correlated with the rotational speed Rv of the shaft 23, that is, the target rotational speed TRv. Therefore, by determining the first determination value Vj1, the second determination value Vj2, and the third determination value Vj3 based on the target rotational speed TRv, the controller 70 can accurately determine the abnormality of the sliding shaft supporting portion 15 regardless of the target rotational speed TRv. Thus, when the abnormality of the sliding shaft supporting portion 15 occurs, the controller 70 can quickly stop the operation of the motor assembly 20, and thus can more suitably prevent the electric pump 1 from failing.

According to the present example embodiment, the controller 70 stops the operation of the motor assembly 20 when the second predetermined period P2 elapses after the determination of the abnormality of the sliding shaft supporting portion 15. As described above, the operation of the motor assembly 20 can be stopped after the fluid R of an amount required by the attachment target device 5 is supplied to the attachment target device 5. Thus, the operation of the attachment target device 5 can be suitably prevented from being unstable.

According to the present example embodiment, upon determining the abnormality of the sliding shaft supporting portion 15, the controller 70 reduces the rotational speed of the shaft 23. Accordingly, as described above, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 in the second predetermined period P2 can be reduced, and thus, the electric pump 1 can be suitably prevented from failing in the second predetermined period P2.

When the electric pump 1 starts to operate after being stopped for a long period of time, the fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15, may have been reduced. In this case, even if the controller 70 determines the abnormality of the sliding shaft supporting portion 15, the pump assembly 40 can be driven by rotating the shaft 23 at a low speed in the second predetermined period P2. Therefore, in the second predetermined period P2, the fluid can be supplied to the sliding shaft supporting portion 15 by the pump assembly 40. Accordingly, the shaft 23 is rotated at a low speed in a state where the fluid amount MR is small, and after the fluid amount MR increases and the rotational speed Rv is stabilized, the rotational speed Rv of the shaft 23 can be increased to the target rotational speed TRv based on the rotational speed command signal CS1.

According to the present example embodiment, the pump assembly 40 supplies the fluid R to the sliding shaft supporting portion 15. Therefore, in the present example embodiment, an additional mechanism for supplying the fluid R to the sliding shaft supporting portion 15 is not required, and thus an increase in the number of components of the electric pump 1 can be suppressed. Therefore, it is possible to suppress an increase in the manufacturing cost and the manufacturing steps for the electric pump 1.

According to the present example embodiment, the fluid R is oil. Therefore, compared with a case where the fluid R is water, the lubricity between the shaft 23 and the sliding shaft supporting portion 15 can be improved by the fluid R. This facilitates the reduction of the frictional force between the shaft 23 and the sliding shaft supporting portion 15, and thus suppression of wearing of each of the shaft 23 and the sliding shaft supporting portion 15 during operation of the electric pump 1 is facilitated. Therefore, the life of the electric pump 1 can be suitably extended.

The controller 70 determines an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 based on the first variation value Vf1 that is a variation value of the rotational speed Rv of the shaft 23, the second variation value Vf2 that is a variation value of the current supplied to the motor assembly 20, or the third variation value Vf3 that is a variation value of the voltage applied to the controller 70 in the first predetermined period P1 in which the target rotational speed TRv of the shaft 23 is a constant speed. As described above, the controller 70 can determine that an abnormality has occurred in the sliding shaft supporting portion 15 based on the first variation value Vf1, the second variation value Vf2, or the third variation value Vf3. Further, when an abnormality occurs in the sliding shaft supporting portion 15, the controller 70 can quickly stop the operation of the motor assembly 20, and thus can suitably prevent the electric pump 1 from failing.

Modification of First Example Embodiment

As illustrated in FIG. 9, an electric pump 101 of the present modification includes a sliding bearing 116. In the following description, components similar to those of the first example embodiment described above are denoted by the same reference signs, and description thereof will be omitted.

A housing 110 of the present modification includes a housing body portion 111, the lid portion 17, the pump cover 19, the motor accommodating portion 10a, and the pump accommodating portion 10c. The housing body portion 111 of the present modification includes the tubular portion 12, the annular wall portion 13, and a sliding shaft supporting portion 115. Thus, the housing 110 includes the sliding shaft supporting portion 115.

The sliding shaft supporting portion 115 has a substantially cylindrical shape that is centered on the rotation axis J, and extends in the axial direction. The shaft 23 passes through the inside of the sliding shaft supporting portion 115 in the axial direction. The sliding shaft supporting portion 115 of the present modification is provided with a hole portion 115e. The hole portion 115e is a hole recessed toward one side in the axial direction, from a surface of the sliding shaft supporting portion 115 facing the other side in the axial direction. As viewed in the axial direction, the hole portion 115e has a substantially circular shape centered on the rotation axis J. The sliding shaft supporting portion 115 of the present modification includes the sliding bearing 116.

The sliding bearing 116 has a substantially annular shape centered on the rotation axis J. In the present modification, the sliding bearing 116 is a sintered bearing in which a porous metal body manufactured by a powder metallurgy method is impregnated with a lubricating oil. The sliding bearing 116 may be made of resin. The sliding bearing 116 is disposed inside the hole portion 115e. The sliding bearing 116 is fixed on the inner circumferential surface of the hole portion 115e. The shaft 23 passes through the inside of the sliding bearing 116 in the axial direction. The inner circumferential surface of the sliding bearing 116 is in contact with the outer circumferential surface of the shaft 23. The shaft 23 is supported by the sliding bearing 116 to be rotatable about the rotation axis J. Thus, the sliding shaft supporting portion 115 functions as a sliding bearing that supports the shaft 23. In the present modification, the pump assembly 40 supplies the fluid R between the shaft 23 and the inner circumferential surface of the sliding bearing 116. That is, the pump assembly 40 supplies the fluid R between the shaft 23 and the sliding shaft supporting portion 115. Accordingly, as in the first example embodiment described above, the fluid R can be suitably interposed between the shaft 23 and the sliding shaft supporting portion 115. Therefore, the shaft 23 and the sliding shaft supporting portion 115 can be suitably lubricated by the fluid R. Other configurations and the like of the housing 110 of the present modification are similar to other configurations and the like of the housing 10 of the first example embodiment described above. The other configurations and the like of the electric pump 101 of the present modification are similar to the other configurations and the like of the electric pump 1 of the first example embodiment described above.

The method of determining an abnormality of the sliding shaft supporting portion 115 of the present modification is the same as the method of determining an abnormality of the sliding shaft supporting portion 15 of the first example embodiment described above. In the present modification, when the fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding bearing 116, decreases, the shaft 23 and the sliding bearing 116 are likely to come into direct contact with each other. This increases the frictional force between the shaft 23 and the sliding bearing 116. Therefore, as in the first example embodiment described above, when the fluid amount MR decreases, the rotational speed Rv of the shaft 23 is unstable. Accordingly, when the fluid amount MR decreases, each of the first variation value Vf1, the second variation value Vf2, and the third variation value Vf3 increases. Thus, as in the first example embodiment described above, the controller 70 can determine that an abnormality has occurred in the sliding shaft supporting portion 115 based on the first variation value Vf1, the second variation value Vf2, or the third variation value Vf3. Thus, when an abnormality occurs in the sliding shaft supporting portion 115, the controller 70 can quickly stop the operation of the motor assembly 20, and thus can suitably prevent the electric pump 101 from failing.

According to the present modification, the sliding shaft supporting portion 115 includes the sliding bearing 116 that supports the shaft 23. Therefore, even if the wear amount of the sliding bearing 116 increases due to a decrease in the amount of the fluid R interposed between the shaft 23 and the sliding bearing 116, the operator or the like can restore the electric pump 101 by replacing only the sliding bearing 116. Therefore, the maintainability of the electric pump 101 can be improved.

Second Example Embodiment

FIG. 10 is a flowchart illustrating an abnormality determination method for an electric pump 201 according to the present example embodiment. In the present example embodiment, when the rotational speed Rv of the shaft 23 is equal to or higher than a first determination speed Rj1 or when the rotational speed Rv of the shaft 23 is equal to or lower than a second determination speed Rj2, a controller 270 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15. In the following description, components similar to those of the first example embodiment described above are denoted by the same reference signs, and description thereof will be omitted.

Although not illustrated, the electric pump 201 of the present example embodiment includes the housing 10, the motor assembly 20, the pump assembly 40, and the controller 270. Although not illustrated, the controller 270 includes the circuit board 71, the motor drive circuit 72, the control unit 75, the storage unit 76, and the first detection unit 77. As in the first example embodiment described above, the first detection unit 77 detects the voltage applied to the coils 33U, 33V, and 33W of the respective phases, and inputs the detection result to the control unit 75. The control unit 75 calculates the rotational speed Rv of the shaft 23 based on the counter electromotive voltage produced in the coil, among the U-phase coil 33U, the V-phase coil 33V, and the W-phase coil 33W, to which the current is not supplied from the motor drive circuit 72. As in the first example embodiment described above, the controller 270 controls the current supplied to the motor assembly 20 to make the rotational speed Rv of the shaft 23 match the target rotational speed TRv.

FIG. 11 is a first diagram illustrating an example of the rotational speed Rv of the shaft 23 in the electric pump 201 of the present example embodiment. The upper graph in FIG. 11 indicates the transition of the fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15. In the present example embodiment, a case will be described where the fluid amount MR is stabilized at a sufficient amount from the time point T0 to the time point T3 and the fluid amount MR monotonously decreases from and after the time point T3. As in the first example embodiment described above, when the fluid amount MR decreases, the shaft 23 and the support surface 15a are likely to come into direct contact with each other, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases.

The lower graph in FIG. 11 indicates the transition of the rotational speed Rv of the shaft 23 calculated by the control unit 75. The rotational speed Rv has an amplitude from the target rotational speed TRv. From the time point T0 to the time point T3 with the fluid amount MR being stable at a sufficient amount, the shaft 23 and the sliding shaft supporting portion 15 can be suitably lubricated by the fluid R, and thus the frictional force between the shaft 23 and the sliding shaft supporting portion 15 can be reduced. As a result, the rotational speed Rv is stabilized, and thus the amplitude of the rotational speed Rv is small. On the other hand, from and after the time point T3 at which the fluid amount MR decreases, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 increases as described above. As a result, the rotational speed Rv is unstable from and after the time point T3, and the amplitude of the rotational speed Rv increases. That is, when the fluid amount MR decreases, the maximum rotational speed of the shaft 23 increases, and the minimum rotational speed of the shaft 23 decreases. Therefore, the controller 270 can determine an abnormality of the sliding shaft supporting portion 15 based on the maximum rotational speed or the minimum rotational speed of the shaft 23. Each of the maximum rotational speed and the minimum rotational speed of the shaft 23 is correlated with the target rotational speed TRv.

As in the first example embodiment described above, the controller 270 includes the determinator 75a. In the present example embodiment, the determinator 75a determines the first determination speed Rj1 and the second determination speed Rj2 based on the target rotational speed TRv. The first determination speed Rj1 and the second determination speed Rj2 are each a threshold for the rotational speed Rv for the controller 270 to determine an abnormality of the sliding shaft supporting portion 15. As illustrated in FIG. 11, the first determination speed Rj1 is a rotational speed higher than the target rotational speed TRv. The second determination speed Rj2 is a rotational speed lower than the target rotational speed TRv. Each of the first determination speed Rj1 and the second determination speed Rj2 is appropriately determined based on the set target rotational speed TRv, the amplitude of the rotational speed Rv when the fluid amount MR decreases at the relevant target rotational speed TRv obtained by measurement in advance, and the like. In the present example embodiment, when the rotational speed Rv of the shaft 23 is lower than the first determination speed Rj1 and higher than the second determination speed Rj2, the controller 270 determines that no abnormality is occurring in the sliding shaft supporting portion 15, and continues the operation of the motor assembly 20. On the other hand, as illustrated in FIG. 11, when the rotational speed Rv of the shaft 23 is equal to or higher than the first determination speed Rj1, the controller 270 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15. As illustrated in FIG. 12, when the rotational speed Rv of the shaft 23 is equal to or lower than the second determination speed Rj2, the controller 270 determines that there is an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15.

FIG. 10 is a flowchart illustrating an abnormality determination method for the sliding shaft supporting portion 15 according to the present example embodiment. When the controller 270 starts the operation of the motor assembly 20, the determinator 75a determines the first determination speed Rj1 and the second determination speed Rj2 based on the target rotational speed TRv (S11). In the present example embodiment, the determinator 75a determines the first determination speed Rj1 and the second determination speed Rj2 based on the target rotational speed TRv every time the target rotational speed TRv is changed.

Next, the controller 270 calculates the rotational speed Rv of the shaft 23 (S12). Next, when the rotational speed Rv is lower than the first determination speed Rj1 (S13) and the rotational speed Rv is higher than the second determination speed Rj2 (S14), the controller 270 determines that the fluid amount MR is sufficient and continues the operation of the motor assembly 20. Thereafter, the controller 270 repeats the above-described operation. On the other hand, when the rotational speed Rv is equal to or higher than the first determination speed Rj1 (S13) as illustrated in FIG. 11, or when the rotational speed Rv is equal to or lower than the second determination speed Rj2 (S14) as illustrated in FIG. 12, the controller 270 determines the abnormality of the sliding shaft supporting portion 15, and transmits the abnormality determination signal Sa to the main body control unit 6 (S06). Upon determining the abnormality of the sliding shaft supporting portion 15 at the time point Tj, the controller 270 immediately transmits the abnormality determination signal Sa to the main body control unit 6.

When the controller 270 transmits the abnormality determination signal Sa to the main body control unit 6, the main body control unit 6 transmits the rotation time command signal CS2 to the control unit 75, as in the first example embodiment described above. The control unit 75 calculates the second predetermined period P2 since the abnormality of the sliding shaft supporting portion 15 is determined until the operation of the motor assembly 20 stops, based on the rotation time command signal CS2. For the rotation time command signal CS2 input to the controller 270 by the main body control unit 6, various modes can be employed as described below. For example, the rotation time command signal CS2 may be a command signal with the second predetermined period P2 being 0 seconds. In this case, as illustrated in FIG. 11, when the rotation time command signal CS2 is received at the time point Tj, the controller 270 quickly stops the supply of the current to the motor assembly 20 and the operation of the motor assembly 20 (S07). In this case, it is possible to suitably suppress the rotation of the shaft 23 in a state where the fluid amount MR interposed between the shaft 23 and the sliding shaft supporting portion 15 is small, and thus it is possible to suitably suppress the failure of the electric pump 201.

The rotation time command signal CS2 may be a command signal for stopping the operation of the motor assembly 20 after the operation of the motor assembly 20 has been continued for the second predetermined period P2 since the controller 270 has determined the abnormality of the sliding shaft supporting portion 15. In this case, as illustrated in FIG. 12, upon receiving the rotation time command signal CS2 at the time point Tj, the controller 270 stops the operation of the motor assembly 20 at a time point T7 after the elapse of the second predetermined period P2 from the time point Tj (S07). Accordingly, the operation of the motor assembly 20 can be stopped after the fluid R of an amount required by the attachment target device 5 is supplied to the attachment target device 5. Thus, the operation of the attachment target device 5 can be prevented from being unstable.

Further, as illustrated in FIG. 12, the controller 270 may lower the rotational speed Rv of the shaft 23 in the second predetermined period P2. Accordingly, the frictional force between the shaft 23 and the sliding shaft supporting portion 15 in the second predetermined period P2 can be reduced, and thus, the electric pump 201 can be suitably prevented from failing in the second predetermined period P2. Other configurations and the like of the controller 270 of the present example embodiment are similar to other configurations and the like of the controller 70 of the first example embodiment described above. The other configurations and the like of the electric pump 201 of the present example embodiment are similar to the other configurations and the like of the electric pump 1 of the first example embodiment described above.

According to the present example embodiment, the electric pump 201 includes the motor assembly 20, the pump assembly 40, the housing 10, and the controller 270 configured to control the operation of the motor assembly 20. The controller 270 includes the determinator 75a configured to determine the first determination speed Rj1 that is a rotational speed higher than the target rotational speed TRv of the shaft 23 and the second determination speed Rj2 that is a rotational speed lower than the target rotational speed TRv, and determines an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 when the rotational speed Rv of the shaft 23 is equal to or higher than the first determination speed Rj1 or when the rotational speed Rv of the shaft 23 is equal to or lower than the second determination speed Rj2. As described above, when the fluid amount MR, which is the amount of the fluid R interposed between the shaft 23 and the sliding shaft supporting portion 15, decreases, the rotational speed Rv is unstable, and thus the amplitude of the rotational speed Rv increases. Accordingly, the controller 270 can determine that an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 has occurred by determining that the rotational speed Rv is equal to or higher than the first determination speed Rj1 or that the rotational speed Rv is equal to or lower than the second determination speed Rj2. Further, when an abnormality occurs in the sliding shaft supporting portion 15, the controller 270 can quickly stop the operation of the motor assembly 20, and thus can suitably prevent the electric pump 201 from failing.

According to the present example embodiment, the determinator 75a determines the first determination speed Rj1 and the second determination speed Rj2 based on the target rotational speed TRv. As described above, each of the maximum rotational speed and the minimum rotational speed of the shaft 23 is correlated with the target rotational speed TRv. Therefore, by determining each of the first determination speed Rj1 and the second determination speed Rj2 based on the target rotational speed TRv, the controller 270 can accurately determine the abnormality of the sliding shaft supporting portion 15 regardless of the target rotational speed TRv. Thus, when the abnormality of the sliding shaft supporting portion 15 occurs, the controller 270 can quickly stop the operation of the motor assembly 20, and thus can more suitably prevent the electric pump 201 from failing.

According to the present example embodiment, the controller 270 includes the determinator 75a configured to determine the first determination speed Rj1 that is a rotational speed higher than the target rotational speed TRv of the shaft 23 and the second determination speed Rj2 that is a rotational speed lower than the target rotational speed TRv, and determines an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 when the rotational speed Rv of the shaft 23 is equal to or higher than the first determination speed Rj1 or when the rotational speed Rv of the shaft 23 is equal to or lower than the second determination speed Rj2. Thus, as described above, the controller 270 can determine that an abnormality due to a shortage of the fluid R in the sliding shaft supporting portion 15 has occurred by determining that the rotational speed is equal to or higher than the first determination speed Rj1 or that the rotational speed Rv is equal to or lower than the second determination speed Rj2. Further, when an abnormality occurs in the sliding shaft supporting portion 15, the controller 270 can quickly stop the operation of the motor assembly 20, and thus can suitably prevent the electric pump 201 from failing.

While the example embodiments of the present disclosure have been described above, the configurations in the example embodiments, combinations thereof, and the like are an example, and additions, omissions, substitutions, and other modifications of the configurations can be made without departing from the spirit of the present disclosure. Note that the present disclosure is not limited to the example embodiments described above.

The controller does not need to be accommodated inside the housing, and may be disposed outside the housing. The controller may calculate the rotational speed of the rotor core, that is, the rotational speed of the shaft, based on a detection result of a sensor such as a Hall element that detects a magnetic field formed by a magnet included in the rotor. The controller may determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion based on the rotational speed of the rotor core.

The configuration of the path through which the fluid flows in the electric pump is an example, and the configuration is not limited to the configurations of the above-described example embodiment and the modification thereof as long as the fluid can be pumped to the outside of the electric pump and the fluid can be supplied between the shaft and the sliding shaft supporting portion.

The use of the electric pump to which the present disclosure is applied is not particularly limited. The type of fluid fed by the electric pump is not particularly limited, and may be a liquid other than oil, such as water. The electric pump may be installed in a device other than the vehicle. The configurations described above in the present specification can be combined as appropriate within a range in which they do not contradict each other.

Note that example embodiments of the present technology can have configurations such as the following.

(1) An electric pump including a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and driven by power of the motor assembly to pump a fluid, a housing to accommodate the motor assembly and the pump assembly and a controller configured or programmed to control an operation of the motor assembly. The housing includes a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft, the fluid is interposed between the shaft and the sliding shaft supporting portion, and the controller is configured or programmed to determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion based on a first variation value that is a variation value of a rotational speed of the shaft, a second variation value that is a variation value of a current supplied to the motor assembly, or a third variation value that is a variation value of a voltage applied to the controller, in a first predetermined period in which a target rotational speed of the shaft is a constant speed.

(2) The electric pump according to (1), wherein the controller is configured or programmed to include a determinator configured or programmed to determine a first determination value, a second determination value, and a third determination value based on the target rotational speed, and the controller is configured or programmed to determine the abnormality due to a shortage of the fluid in the sliding shaft supporting portion when the first variation value is equal to or larger than the first determination value, when the second variation value is equal to or larger than the second determination value, or when the third variation value is equal to or larger than the third determination value.

(3) An electric pump including a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and driven by power of the motor assembly to pump a fluid, a housing to accommodate the motor assembly and the pump assembly and a controller configured or programmed to control an operation of the motor assembly. The housing includes a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft, the fluid is interposed between the shaft and the sliding shaft supporting portion, and the controller is configured or programmed to include a determinator configured or programmed to determine a first determination speed being a rotational speed higher than a target rotational speed of the shaft and a second determination speed being a rotational speed lower than the target rotational speed, and determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion when a rotational speed of the shaft is equal to or higher than the first determination speed or is equal to or lower than the second determination speed.

(4) The electric pump according to (3), wherein the determinator is configured or programmed to determine the first determination speed and the second determination speed based on the target rotational speed.

(5) The electric pump according to any one of (1) to (4), wherein the controller is configured or programmed to stop the operation of the motor assembly when a second predetermined period elapses after the determination of the abnormality.

(6) The electric pump according to any one of (1) to (4), wherein the controller is configured or programmed to reduce the rotational speed of the shaft when the controller determines the abnormality.

(7) The electric pump according to any one of (1) to (6), wherein the pump assembly supplies the fluid to the sliding shaft supporting portion.

(8) The electric pump according to any one of (1) to (7), wherein the fluid is oil.

(9) The electric pump according to any one of (1) to (8), wherein the sliding shaft supporting portion includes a sliding bearing to support the shaft.

(10) A controller configured or programmed to control an operation of an electric pump including a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and driven by power of the motor assembly to pump a fluid, and a housing to accommodate the motor assembly and the pump assembly, the housing including a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft, the fluid being interposed between the shaft and the sliding shaft supporting portion, the controller is configured or programmed to determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion based on a first variation value that is a variation value of a rotational speed of the shaft, a second variation value that is a variation value of a current supplied to the motor assembly, or a third variation value that is a variation value of a voltage applied to the controller, in a first predetermined period in which a target rotational speed of the shaft is a constant speed.

(11) A controller configured or programmed to control an operation of an electric pump including a motor assembly including a shaft rotatable about a rotation axis, a pump assembly coupled to an end portion of the shaft on one side in an axial direction and driven by power of the motor assembly to pump a fluid, and a housing to accommodate the motor assembly and the pump assembly, the controller is configured or programmed to include a determinator configured or programmed to determine a first determination speed being a rotational speed higher than a target rotational speed of the shaft and a second determination speed being a rotational speed lower than the target rotational speed, wherein the housing includes a motor accommodating portion to accommodate the motor assembly, a pump accommodating portion to accommodate the pump assembly, and a sliding shaft supporting portion to support the shaft, the fluid is interposed between the shaft and the sliding shaft supporting portion, and the controller is configured or programmed to determine an abnormality due to a shortage of the fluid in the sliding shaft supporting portion when a rotational speed of the shaft is equal to or higher than the first determination speed or is equal to or lower than the second determination speed.

Features of the above-described example embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.

While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.