FLUID PUMP WITH INLET SEAL DEVICE

Description

BACKGROUND

Automotive coolant pumps are used to distribute coolant through various vehicle systems to maintain desired operating temperatures of vehicle components including the engine, the battery, electronics, the passenger cabin, etc. The hydraulic components of a pump consist of an impeller and a pump housing. The impeller rotates within the pump housing, drawing in coolant through the inlet portion of the pump housing and discharging it into the volute portion of the pump housing. There is a necessary clearance gap between the impeller and the pump housing. The clearance gap prevents the impeller from impinging on the pump housing and causing damage to either the impeller or pump housing. Automotive pumps may be manufactured out of molded plastic components and the dimensional tolerances required of molded plastic parts results in a running clearance gap large enough to cause a large portion of the pump inflow to go through the impeller and then to recirculate through the clearance gap and return to the inlet of the impeller. As much as 20%-30% of the flow through the impeller can recirculate through the clearance gap. The recirculation via the clearance gap is an undesirable inefficiency. It is desirable to reduce recirculation via the clearance gap to improve pump efficiency.

SUMMARY

A fluid pump includes a seal device that reduces recirculation and increases pump efficiency. The seal device provides a fluid seal between an end surface of a rotating impeller and a fixed pump housing. The seal device is a ring that has a break in continuity in the form of a slot. In the seal device, the slot separates a first circumferential end from a second circumferential end of the seal device. The seal device has a generally rectangular cross-section with a chamfer between a first axial end and an inner radial side configured such that only a portion of the inner radial side contacts a surface of the pump housing. In addition, a line contact is formed between a base of the seal device and the end surface of the rotating impeller. The pump housing includes a projection that protrudes the slot between the first and second circumferential ends so as to prevent rotation of the seal device. The net of the high pressure and low pressure acting on the seal device causes a radially inward force and a small axial force toward the impeller that results in the increased torque applied by the seal device on the impeller being small enough to limit pump efficiency losses caused by the seal device.

In some aspects, a fluid pump includes a pump housing. The pump housing has a fluid inlet that is concentric with a rotational axis of an impeller and a fluid outlet that is oriented at a non-zero angle relative to the rotational axis. The pump housing has an inner surface that defines an annular channel that encircles the fluid inlet, and a volute that surrounds the annular channel. The fluid pump includes an impeller that is disposed inside the pump housing and configured to rotate relative to the pump housing about the rotational axis. The impeller includes a base plate, a curved shroud that is axially aligned with the base plate, and blades that extend between the base plate and the shroud. In addition, the fluid pump includes a seal device that is disposed in the channel. A first portion of the seal device directly contacts a surface of the channel and a second portion of the seal device directly contacts a surface of the impeller.

In some embodiments, a fluid-tight first seal exists between the first portion and the surface of the channel, and a fluid-tight second seal exists between the second portion and the surface of the impeller.

In some embodiments, the first portion and the surface of the channel each have a conical shape when viewed in cross section.

In some embodiments, when the fluid pump is operating, fluid passing through the pump applies a first pressure to a first region of the seal device that extends between the first seal and the second seal and includes a first axial end of the seal device, and a second pressure to a second region of the seal device that extends between the first seal and the second seal and includes a second axial end of the seal device. The first pressure is greater than the second pressure, and the second axial end of the seal device faces the impeller.

In some embodiments, when the fluid pump is operating, a pressure differential exists in the pump housing and across the seal device that increases the fluid tightness of each of the first seal and the second seal.

In some embodiments, the seal device has an annular structure that is circumferentially discontinuous.

In some embodiments, the seal device is able to translate axially in the channel.

In some embodiments, the seal device has an axial dimension that is in a range of five times to twenty times a radial dimension of the seal device.

In some embodiments, the channel extends axially and has a blind end.

In some embodiments, the seal device includes an outer circumference, a first circumferential end, a second circumferential end and a slot dimension that corresponds to the minimum distance between the first circumferential end and the second circumferential end along a circumferential direction of the seal device. The slot dimension is in a range of 0.5 percent to 10.0 percent of the outer circumference.

In some embodiments, the seal device includes a first axial end, a second axial end that is opposite the first axial end, a radially-inward surface that faces the fluid inlet and a radially-outward surface that is opposite the radially-inward surface. The radially-inward surface has multiple circumferentially-elongated facets.

In some embodiments, the seal device includes a first axial end, a second axial end that is opposite the first axial end, a radially-inward surface that faces the fluid inlet and a radially-outward surface that is opposite the radially-inward surface. The first portion of the seal device is disposed on the radially inward surface and the second portion of the seal device corresponds to an edge that adjoins the radially outward surface.

In some embodiments, the seal device includes a first axial end, a second axial end that is opposite the first axial end, a radially-inward surface that faces the fluid inlet and a radially-outward surface that is opposite the radially-inward surface. The radially-inward surface includes a first facet that is oriented at a first angle relative to the rotational axis and a second facet that is oriented at a second angle relative to the rotational axis. The first angle is different than the second angle. When the fluid pump is operating, fluid passing through the pump applies a first pressure to the first facet and a second pressure to the second facet, and the first pressure is different than the second pressure.

In some embodiments, the first pressure is greater than the second pressure.

In some embodiments, the first portion of the seal device is disposed between the first facet and the second facet.

In some embodiments, the seal device includes a first axial end, a second axial end that is opposite the first axial end, a radially-inward surface that faces the fluid inlet and a radially-outward surface that is opposite the radially-inward surface. The radially inward surface includes a first facet that is disposed between the first portion and the first axial end and is oriented at a first angle relative to the rotational axis. The radially inward surface includes a second facet that corresponds to the first portion, the second facet being oriented at a second angle relative to the rotational axis. In addition, the radially inward surface includes a third facet that is disposed between the second facet and the second axial end and is oriented at a third angle relative to the rotational axis. The first angle is different than the second angle and the third angle. The second angle is different from the third angle.

In some embodiments, the first facet adjoins the first axial end and has a radius at a first axial location that is greater than a radius of the surface of the channel at a corresponding axial location.

In some embodiments, the third facet adjoins the second axial end and is free of contact with the surface of the channel.

In some embodiments, the second axial end extends between the third facet and the radially-outward surface, the second axial end is non-perpendicular relative to the radially-outward surface, and the second axial end is non-perpendicular relative to the third facet.

In some embodiments, the fluid pump includes a spring element disposed in the channel between the seal device and a blind end of the channel.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a fluid pump.

FIG. 2 is a cross-sectional view of the fluid pump of FIG. 1 as seen across line 2-2 of FIG. 1.

FIG. 3 is a perspective view of an inside surface of the cap portion of the housing.

FIG. 4 is an enlarged view of a portion of the cross-sectional view of FIG. 2 illustrating the seal device disposed in the channel.

FIG. 5 is a cross-sectional view of the cap portion of the housing as seen along line 5-5 of FIG. 1.

FIG. 6 is a perspective view of the seal device in isolation from the fluid pump.

FIG. 7 is a cross-sectional view of the seal device as seen along line 7-7 of FIG. 6.

FIG. 8 is an enlarged cross-sectional view of a portion of FIG. 4 illustrating the pressure differential across the seal device. In FIG. 8, a first region R1 (represented by a solid line) of high pressure (represented by open arrows) is disposed on a downstream side of the impeller, while a second region R2 (represented by broken lines) of relatively lower pressure P2 is disposed on an upstream side of the impeller.

FIG. 9 is an enlarged view of a portion of the cross-sectional view of FIG. 2 illustrating an alternative embodiment of the fluid pump that includes an elastic member in the channel.

FIG. 10 is an enlarged cross-sectional view of a portion of FIG. 4 illustrating an alternative embodiment of the impeller shroud.

DETAILED DESCRIPTION

Referring to FIGS. 1-4, a volute-type centrifugal liquid-cooled fluid pump 10 includes a pump casing 12 that defines a “wet area” through which fluid is pumped, and an electric drive 40 that drives the pump 10. The pump casing 12 is formed by a first casing part referred to as the pump housing 14 and a second casing part referred to as the motor pot 30. The pump housing 14 includes a hollow, cylindrical container portion 14(1) and a cover portion 14(2) that closes an open end of the container portion 14(1). The motor pot 30 is a cup-shaped structure including an open end 31 that faces the cover portion 14(2). The cover portion 14(2) is also generally cup shaped and has an open end 15 that faces the motor pot 30. The cover portion 14(2) and motor pot 30 are assembled with the respective open ends 15, 30 adjoining to form an enclosed fluid chamber 36. The fluid chamber 36 forms the wet area of the pump 10 and receives an impeller 56 that draws fluid into the fluid chamber 36 via a fluid inlet 16, increases the fluid pressure and then discharges the pressurized fluid via a fluid outlet 17. The pump 10 includes a seal device 100 that surrounds a portion of the fluid inlet 16 and extends into the clearance gap 22 between a shroud 90 of the impeller 56 and the housing inner surface 18. When the pump 10 is operating, the seal device 100 provides fluid seal between an end surface of the impeller 56 and a surface of the cover portion 14(2), as will be described in detail below.

The cover portion 14(2) includes the fluid inlet 16 and the fluid outlet 17. In addition, the cover portion 14(2) includes a volute 21 formed in the pump housing inner surface 18 and an annular channel 20 that is formed in the pump housing inner surface between the volute 21 and the fluid inlet 16.

A main volume flow of the fluid flows in through the fluid inlet 16 in an axial direction into the fluid chamber 36 and then enters the impeller 56 which redirects the fluid into the volute 21. As used herein, the term “axial direction” denotes the axial direction of the fluid pump, which coincides with a rotational axis 48 of the impeller 56. The term “radial plane” refers to a plane that is perpendicular to or substantially perpendicular to the axial direction and is parallel to the plane in which the volute 21 of the cover portion 14(2) extends. The term “radial direction” to a direction which extends substantially perpendicular to the axial direction and/or to the axis of rotation 48. In particular, the radial direction lies in the radial plane. The use of the term “substantially” is an acknowledgement that some minor variation in relative orientation may occur. In some cases, the variation may be due to manufacturing tolerances, wear of components, etc. In some embodiments, the term “substantially” as used herein refers to a direction that is within plus or minus two degrees of being precisely as stated, while in other embodiments the term “substantially” refers to a direction that is within plus or minus five degrees of being precisely as stated.

The volute 21 is configured to efficiently collect fluid from the impeller 56. The volute 21 forms a spiral fluid path 23 centered on the fluid inlet 16 and extending in the radial plane. The spiral fluid path 23 partially encircles the fluid inlet 16. Although the arc length of the spiral fluid path 23 is determined by the requirements of the specific application, an exemplary spiral fluid path 23 may have an arc length of about 330 degrees. The volute 21 is open so as to face the open end 31 of the motor pot 30 and is configured to discharge fluid toward the fluid outlet 17. The fluid outlet 17 is non-parallel to, and non-intersecting with, the fluid inlet 16. For example, the fluid outlet 17 may be radially offset relative to the fluid inlet and extend in a direction that is substantially perpendicular to the fluid inlet 16. I

The described arrangement in which the fluid inlet 16 is arranged substantially parallel to and coaxial with the axis of rotation 48 of the impeller 56 and the fluid outlet 17 extends in radial direction that is perpendicular to or substantially perpendicular to the rotational axis 48 enables a particularly compact design of the pump 10 or the pump housing 14.

The channel 20 encircles the fluid inlet 16 and is centered on the rotational axis 48. The channel 20 is located closely adjacent to the fluid inlet 16 whereby a narrow annular pump inlet lip 24 separates the channel 20 from the fluid inlet 16. The channel 20 extends generally axially and opens facing the open end 31 of the motor pot 30. The channel 20 has a radially-innermost surface 25 that corresponds to an outer surface of the pump inlet lip 24. In addition, the channel 20 has a radially-outermost surface 26 that faces and is spaced apart from the radially-innermost surface 25 and a blind end 28 that joins the radially-innermost and outermost surfaces 25, 26. Although the radially-outermost surface 26 extends substantially axially, the radially-innermost surface 25 has a conical portion 29 at the intersection with the pump housing inner surface 18 so that the channel opening is larger than the blind end 28 when the channel 20 is viewed in a side cross-section.

In some embodiments, the pump inlet lip 24 includes a protrusion 39 that protrudes radially from the channel radially-innermost surface 25 into the channel 20. The protrusion 39 is received in a slot 101 of the seal device 100.

The cover portion 14(2), the motor pot 30 and the container portion 14(1) are retained in the assembled configuration via fasteners 13. The motor pot 30 separates the wet area from the dry area, which includes most components of the electric drive 40. The electric drive 40 has a rotor unit 50, a stator 80 and includes control electronics which are referred to generally by reference number 42. Since the structure and functionality of a suitable electric motor are sufficiently known from the prior art, a detailed description of the electric drive 40 is omitted for brevity.

The pump 10 includes an annular casing seal 99 that is disposed between the motor pot 30 and the cover portion 14(2). The casing seal 99 is disposed on an outer periphery of the motor pot 30 so as to surround the open end 31. In addition, the casing seal 99 abuts the inner surface 18 of the cover portion 14(2) so as to surround the volute 21 in a radial plane. The casing seal 99 provides a fluid-tight seal between the cover portion 14(2) and the motor pot 30.

The rotor unit 50 is disposed in the fluid chamber 36 and includes a rotor 52 and the impeller 56, which are connected to one another in a rotationally fixed manner whereby movement of the rotor 52 is transmitted to the impeller 56. When the pump 10 is in operation, the rotor unit 50 conveys fluid through the wet area by means of the impeller 56. The rotor unit 50 is discussed in more detail below.

The stator 80 is disposed outside the motor pot 30 (e.g., the stator 80 is disposed in the dry area) and is controlled by the control electronics 42. The stator 80 includes a plurality of coils 82 that encircle the motor pot 30 in the vicinity of the rotor 52 along the circumference of the rotor 52. When the electric drive 40 is in operation, the stator coils 82 generate a rotating magnetic field, by means of which the rotor unit 50 is driven to rotate about a rotational axis 48.

The rotor unit 50 is rotatably mounted on a pump shaft 53 via a plain bearing 60. The pump shaft 53 extends axially and is fixed relative to the pump casing 12. The rotational axis 48 runs through the center of the pump shaft 53 in the axial direction and thus corresponds to the centerline of the pump shaft 53. In addition, the rotational axis 48 is aligned with a centerline of the pump housing fluid inlet 16.

A first end 54 of the pump shaft 53 faces the pump housing inlet 16 and is connected in a rotationally fixed manner to a stop element 62 that prevents the rotor 52 from moving in the axial direction toward the pump fluid inlet 16. During operation, such an axial deflection of the impeller 56 may be generated, for example, by the axial thrust of the rotor 52. The stop element 62 is a single metal part that includes a thrust washer 64 and webs 63. The thrust washer 64 resides between the stop element 62 and the bearing 60. In addition, the shaft second end 55 is fixed in a boss 61 that protrudes from the motor pot closed end 32, for example by a press fit or overmolding.

The motor pot 30, having a cup shaped structure, includes a generally cylindrical sidewall 33. The motor pot open end 31 faces the cover portion 14(2) and is surrounded by a flange 34 that abuts the open end 15 of the cover portion 14(2). Opposite the motor pot open end 31, the motor pot 30 includes the closed end 32. The motor pot closed end 32 is generally planar, parallel to the open end and faces the control electronics 42. The boss 61 protrudes axially from the inner surface of the closed end 32.

The rotor unit 50 includes the impeller 56 and the rotor 52 that drives the impeller 56. The impeller 56 includes a base plate 59, the hub 51 that is centered on the base plate 59 and protrudes from one side thereof, impeller blades 57 that protrude from the opposite side of the base plate 59, and a curved shroud 90. The base plate 59 extends as a substantially flat disk in the radial direction. The impeller blades 57 are arranged on the base plate 59 and extend in a spiral around the rotational axis 48. The impeller blades 57 are arranged between the base plate 59 and the shroud 90 and face the fluid inlet 16. The impeller 56 is arranged within the fluid chamber 36 such that the base plate 59 is disposed at the open end 31of the motor pot 30 and the shroud 90 is disposed between the base plate 59 and the cover portion 14(2). In this location, the shroud 90 overlies the impeller blades 57.

The shroud 90 has a concavely curved cross-sectional shape when viewed in a direction perpendicular to the rotational axis 48. In some embodiments, the shroud 90 may resemble a bell portion of a trumpet. An outer surface 92 of the shroud 90 faces, and is closely spaced relative to, the inner surface 18 of the cover portion 14(2). As previously discussed, the gap between the shroud outer surface 59 and the cover portion inner surface 18 is referred to as the clearance gap 22. An inner surface 91 of the shroud 90 rests on the free edges of the impeller blades 57.

The shroud 90 includes an inlet end surface 94 that extends in a radial plane between the shroud inner and outer surfaces 91, 92. The inlet end surface 94 faces the pump inlet lip 24 and the channel 20. In addition, the inlet end surface 94 defines a shroud central opening 93 that faces and is concentric with the fluid inlet 16 of the cover portion 14(2). The shroud central opening 93 serves as an inlet to the impeller 56. The central opening 93 permits fluid from the fluid inlet 16 to be directed into the impeller blades 57.

The shroud 90 includes an outlet end surface 96 that extends in a radial plane between the shroud inner and outer surfaces 91, 92. The outlet end surface 96 faces the volute 21, and the gap between the outer periphery of the impeller base plate 59 and the outlet end surface 97 serves as an outlet to the impeller 56.

The impeller 56 draws fluid from the pump housing inlet 16 in an axial direction through the shroud central opening 93 and redirects the main volume flow from an axially-directed flow to a radially-directed flow. Fluid exits the impeller 56 in a radial direction at a periphery of the base plate 59 through the impeller outlet. Fluid exiting the impeller 56 flows out of the fluid chamber 36 via the volute 21 that is incorporated into the cover portion 14(2).

A narrow clearance gap 22 is disposed between the shroud outer surface 92 and the pump housing inner surface 18. The clearance gap 22 prevents the impeller 56 from impinging on the cover portion 14(2) and causing damage to either the impeller 56 or the cover portion 14(2). The clearance gap 22 communicates with the channel 20 that is formed in the pump housing inner surface between the volute 21 and the fluid inlet 16.

Referring to FIGS. 4-8, the fluid pump 10 includes a seal device 100 positioned on the pump inlet lip 24 whereby the seal device 100 is disposed in the channel 20 and protrudes into the clearance gap 22. The seal device 100 expands in diameter as it is installed on the pump inlet lip 24. When installed, the seal device 100 applies a small radial inward force that results from an interference fit. For example, in some embodiments, the small radial inward interference force is in a range of 2N to 5 N. In addition, the seal device 100 is disposed in the channel 20 in such way that the seal device 100 is able to translate axially.

The seal device 100 is configured to have a static contact with the pump inlet lip 24 and a dynamic or sliding contact with a surface of the impeller shroud 90, as described in detail below. In some embodiments, the seal device 100 partially obstructs the clearance gap 22 whereby recirculation of fluid through the clearance gap 22 is reduced and pump efficiency is increased. In other embodiments, the seal device 100 fully obstructs the clearance gap 22 whereby fluid recirculation is prevented and pump efficiency is increased.

The seal device 100 has an annular structure having a diameter that is slightly smaller than the mating surface of the fluid inlet 16 and a generally rectangular cross-sectional shape. The seal device 100 includes a first axial end 106 and a second axial end 108 that is opposite the first axial end 106. The seal device 100 also includes a radially-inward surface 128 that faces the fluid inlet 16 and a radially-outward surface 130 that is opposite the radially-inward surface 128. The cross-section is elongated in a direction generally parallel to the seal device axis of symmetry 105. For example, the seal device 100 has an axial dimension that is in a range of five to twenty times a radial dimension of the seal device 100. When used describing the seal device 100, the terms “radial” and “axial” are made with reference to pump the axis of symmetry 105 of the seal device 100. When the seal device 100 is installed in the fluid pump 10, the axis of symmetry 105 of the seal device is aligned with the rotational axis 48 of the fluid pump 10 and the terms “radial” and “axial” are made with reference to the rotational axis of the fluid pump 10.

Although the seal device 100 is generally rectangular in cross-sectional shape, a more precise description is that the first axial end 106 is perpendicular to the axis of symmetry 105 whereas the second axial end 108 is non-parallel with respect to the first axial end 106. In addition, the radially-inward surface 128 has three circumferentially elongated facets 134, 136, 138 including a chamfered facet 134 that is defined by a chamfer that adjoins the first axial end 106, an axially-extending facet 138 that adjoins the second axial end 108 and a conical facet 136 that extends between the chamfered facet 134 and the axially-extending facet 138.

The chamfered facet 134 provides a lead-in that facilitates installation of the seal device 100 on the pump inlet lip 24. The chamfered facet 134 is a surface that lies at a first angle θ₁ relative to the axis of symmetry 105. In some embodiments, the first angle is in a range of 35 degrees to 55 degrees. As a result, an inner radius of the seal device 100 at the first axial end 106 is greater than a corresponding radius of the pump inlet lip 24, whereby a gap exists between the chamfered facet 134 and the pump inlet lip 24.

In the illustrated embodiment, the axial dimension of the chamfered facet 134 is small relative to the overall axial dimension of the seal 100. For example, the axial dimension of the chamfered facet 134 may be two percent to twenty percent of the seal device overall axial dimension.

The conical facet 136 is a surface that lies at a second angle θ₂ relative to the axis of symmetry 105. The second angle θ₂ is less than the first angle θ₁. In some embodiments, the second angle θ₂ is approximately one-third of the first angle θ₁.

The conical facet 136 directly contacts a surface 29 of similar conical shape on the pump inlet lip 24. In the illustrated embodiment, the conical facet 136 has the same slope and a smaller diameter than the mating conical surface 29 of the pump inlet lip 14. This configuration forces the seal device 100 to expand to fit over the pump inlet lip 24.

When the pump 10 is operating, the conical facet 136 directly contacts the conical surface 29 of the pump inlet lip 24 and provides a static first seal 150 between the seal device 100 and the pump inlet lip 24. Thus, the conical facet 136 of the seal device 100 provides a static seal contact surface. Because the conical facet 136 has a conical shape, a portion of the interference force is directed towards the impeller shroud 90, which helps the seal device 100 maintain a sliding contact with the impeller 56.

The required radial dimensional tolerances are modest as the seal device 100 expands on the conical surface 29 of the pump inlet lip 24. The required axial dimensional tolerances of the parts are very modest, as the seal device 100 is free to move in the axial direction and still maintains contact with the pump inlet lip 24. In the illustrated embodiment, the axial dimension of the conical facet 136 is small relative to the overall axial dimension of the seal 100 in order to limit misalignment due to surface tolerances. For example, the axial dimension of the conical facet 136 may be ten percent to thirty percent of the seal device overall axial dimension.

The axially-extending facet 138 is a surface that lies at a third angle θ₃ relative to the axis of symmetry 105. In the illustrated embodiment, the third angle θ₃ is substantially zero, whereby the axially-extending facet 138 is parallel to the radially-outward surface 130 and is generally parallel to the axis of symmetry 105.

In the illustrated embodiment, the axial dimension of the axially-extending facet 138 is large relative to the overall axial dimension of the seal 100. For example, the axial dimension of the axially-extending facet 138 may be forty-five percent to eighty percent of the seal device overall axial dimension.

The first axial end 106 is substantially perpendicular to the axially-extending facet 138 while the second axial end 108 is angled relative to the axially-extending facet 138. For example, in the illustrated embodiment, the second axial end 108 is at a fourth angle θ₄ relative to the axis of symmetry 105. The fourth angle θ₄ is greater than the first angle θ₁. In some embodiments, the fourth angle θ₄ is approximately twice the first angle θ₁. The fourth angle θ₄ is configured so that the outer radial edge 132 protrudes axially relative to the inner radial edge 131. This configuration ensures that, during operation of the pump 10, a low pressure region interfaces with the second axial end 108 of the seal 100, as discussed further below. In use, the outer radial edge 132 directly contacts the impeller 56 (e.g., the outer radial edge 132 directly contacts the shroud inlet end surface 94) and provides a dynamic second seal 152 between the seal device 100 and the impeller 56. The edge 132 will wear down during use while maintaining the second seal 152. After sufficient use, the shape of the second axial end 108 will conform to the shape of the shroud inlet end surface 94.

The seal device 100 has an outer circumference 126 that is defined by the radially-outward surface 130 and is represented by a broken line, and an inner circumference 124 that is defined by the radially-inward surface 128 and is represented by a dot-dashed line. The inner and outer circumferences 124, 126 are on opposite sides of the seal device 100 and are separated by the radial thickness of the seal device 100.

The seal device 100 is circumferentially discontinuous, e.g., the seal device 100 includes a slot 101 (FIGS. 5 and 6). The slot 101 extends through the radial thickness from the first axial end 106 to the second axial end 108. As a result, the seal device 100 includes a first circumferential end 110 that faces and is spaced apart from a second circumferential end 112. In the illustrated embodiment, the slot dimension is in a range of 0.5 percent of the outer circumference to ten percent of the outer circumference, where the dimension of the slot 101 corresponds to the minimum distance between the first circumferential end 110 and the second circumferential end 112 along the outer circumference 126 of the seal device 100.

When the seal device 100 is mounted on the pump inlet lip 24, the seal device 100 is oriented so that the slot 101 receives the protrusion 39 that protrudes from the channel radially-innermost surface 25 into the channel 20 (FIG. 5). Depending on the specific application, the protrusion 39 may limit or prevent circumferential movement of the seal device 100 relative to the pump housing 14 while permitting axial movement. In addition, a first portion 102 of the seal device 100 directly contacts a surface of the channel 20. In the illustrated embodiment, the first portion 102 of the seal device 100 is disposed on the seal device radially inward surface 128 and corresponds to the conical facet 136, which directly contacts a corresponding conical surface 29 of the pump inlet lip 24. In addition, a second portion 104 of the seal device 100 directly contacts a surface of the impeller 56. In the illustrated embodiment, the second portion 104 of the seal device 100 corresponds to the outer radial edge 132 of the seal second axial end 108. The outer radial edge 132, which adjoins the seal device radially outward surface 130, directly contacts the inlet end surface 94 of the shroud 90 (FIG. 8).

During pump operation, fluid passing through the pump 10 applies a first pressure P1 (represented by open arrows) to a first region R1 (represented by an unbroken line) of the seal device 100. The first region R1 extends between the first seal 150 and the second seal 152 and includes the seal device first axial end 106. In addition, during pump operation, fluid passing through the pump 10 applies a second pressure P2 (represented by solid arrows) to a second region R2 (represented by a broken line) of the seal device 100. The second region R2 extends between the first seal 150 and the second seal 152 and includes the seal device second axial end 108. The first pressure P1 is greater than the second pressure P2, whereby a fluid pressure gradient exists between the radially inward surface 128 and the radially outward surface 130. As a result of the pressure differential between the first region R1 and the second region R2, the first seal 150 is formed between the seal device 100 and the pump housing 14, the second seal 152 is formed between the seal device 100 and the shroud 90 of the impeller 56, and both the first seal 150 and the second seal 152 are fluid tight seals.

For the seal device 100 to function properly, the seal device 100 must maintain the static contact with the pump inlet lip 24 and maintain the sliding contact with the shroud inlet end surface 94. A force must be applied to the seal device 100 in both a radially inward direction, against the pump inlet lip 24, and in an axial direction, towards the impeller shroud 90. The applied forces may be achieved by utilizing the pressure differential between the impeller inlet and outlet.

The function of a pump impeller 56 is to provide a pressure increase to the fluid passing through the impeller 56. On the downstream side of the impeller 56, the fluid pressure is greater than that at the upstream side of the impeller 56. This pressure difference is also present across the pump seal device 100. The distribution of the high pressure fluid P1 on the downstream surfaces R1 of the seal device 100 provide a radially inward force and an axial force toward the impeller shroud 90. The distribution of the lower pressure fluid P2 on the upstream surfaces R2 of the seal device 100 provide a radially outward force and an axial force away from the impeller shroud 90. Due to the higher pressure and larger surface area on the downstream surfaces R1, the force balance results in a small net radially inward force and a small net axial force towards the impeller shroud 90. This force on the impeller shroud 90 is small enough that the resulting increase in torque due to friction between the impeller shroud 90 and the seal device 100 is small, for example small enough that there is a net increase in pump efficiency.

Due to the sliding velocity of the impeller shroud 90, a hydrostatic film may be established between the seal device 100 and the impeller shroud 90, further reducing the friction coefficient and the wear of the seal device 100. Adjustments to the shape of the second axial end 108 of the seal device 100 may be made to establish or optimize a hydrostatic film.

Referring to FIG. 9, if the resultant net axial force is too small, a mechanical spring element 160 may be included to provide the necessary axial force. For example, a mechanical spring may be used to urge the seal device 100 into contact with the inlet end surface 94 of the impeller 56 and provide the desired axial force of the seal device 100 acting on the impeller 56.

As there is a sliding contact between the seal device 100 and the impeller shroud 90, wear may occur. The seal device 100 must be of a lower hardness than the impeller shroud 90 for the wear to occur on the seal device 100. The seal device material should be low friction and wear resistant, and materials such as polyoxymethylene (POM), Polytetrafluoroethylene (PTFE) or Ultra-high-molecular-weight polyethylene (UHMWPE) could be used.

Referring to FIG. 10, in some embodiments, the impeller 56 includes an alternative embodiment shroud 290. The shroud 290 shown in FIG. 10 is similar to the shroud 90 described with respect to FIGS. 1-9 and common elements are referred to with common reference numbers. The shroud 290 shown in FIG. 10 differs from the previous embodiment in that the shroud 290 includes an insert 292 that is fixed to the shroud inlet end face 294, for example using adhesive or other appropriate fixation techniques. The insert 292 may be formed of a different material than the shroud 290. In particular, the insert 292 may be formed of a material having a hardness that is greater than the hardness of the seal device 100 so that any wear that occurs during pump operation occurs in the pump seal 100 rather than the insert 292. By providing the shroud 290 with the insert 290, the shroud 290 may be formed of a less expensive material than the insert 292.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the inventive concepts that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.