WORK MACHINE, WORK MACHINE CONTROL METHOD, AND WORK MACHINE CONTROL SYSTEM

Description

TECHNICAL FIELD

The present disclosure relates to a state of a work machine, and particularly to a technique for determining a state of a slewing bearing.

BACKGROUND ART

In general, inspection of the amount of wear of a slewing bearing in a work machine is periodically carried out in accordance with the elapsed operation time of the work machine. When the amount of wear of the slewing bearing is found to be beyond an allowable value, it is judged that the slewing bearing needs to be replaced (inspected).

In this regard, a scheme has been proposed in which vibration, sound, and the like of a slewing bearing are measured by sensors to estimate the amount of wear of the slewing bearing (see Patent Document 1).

CITATION LIST

Patent Literature

Patent Document 1: JP 2021-147772 A

SUMMARY OF INVENTION

Technical Problem

On the other hand, the sensors provided in the slewing bearing are easily affected by disturbance, which makes it difficult to determine the state of the slewing bearing with high accuracy.

An object of the present disclosure is to provide a work machine, a method of controlling a work machine, and a control system of a work machine, which are capable of determining a state of a slewing bearing with high accuracy.

Solution to Problem

A work machine according to an aspect of the present disclosure includes: a slewing bearing; a drive device configured to drive the slewing bearing; a detection unit configured to detect a state of at least one of input to the drive device and output from the drive device; and a determination unit configured to determine a state of the slewing bearing based on a detection value detected by the detection unit.

A method of controlling a work machine according to an aspect of the present disclosure includes: a step of driving a slewing bearing; a step of detecting a state of at least one of input to a drive device configured to drive the slewing bearing and output from the drive device; and a step of determining a state of the slewing bearing based on a detected detection value.

A control system of a work machine according to an aspect of the present disclosure includes: a slewing bearing; a drive device configured to drive the slewing bearing; a detection unit configured to detect a state of at least one of input to the drive device and output from the drive device; and a determination unit configured to determine a state of the slewing bearing based on a detection value detected by the detection unit.

Advantageous Effects of Invention

The work machine, the method of controlling the work machine, and the control system of the work machine according to the present disclosure are capable of determining the state of a slewing bearing with high accuracy.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a work machine according to a first embodiment.

FIG. 2 is a plan view of the work machine according to the first embodiment.

FIG. 3 is a diagram explaining a main part of a rotating device according to the first embodiment.

FIG. 4 is a diagram explaining a swing circle 220 according to the first embodiment.

FIG. 5 explains a general block diagram illustrating a configuration of a rotation system of the work machine according to the first embodiment.

FIG. 6 is a flowchart explaining abnormality determination made for a slewing bearing by a controller 10 according to the first embodiment.

FIG. 7 is a diagram explaining changes in motor pressures as hydraulic pressure values of hydraulic pressure sensors 242, 244 and frequency characteristics in the slewing bearing at a normal time according to the first embodiment.

FIG. 8 is a diagram explaining changes in first and second motor pressures as hydraulic pressure values of the hydraulic pressure sensors 242, 244 and frequency characteristics in the slewing bearing at an abnormal time according to the first embodiment.

FIG. 9 is a diagram explaining comparison determination of abnormality of the slewing bearing according to the first embodiment.

FIG. 10 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to a modification of the first embodiment.

FIG. 11 is a flowchart explaining abnormality determination made for a slewing bearing by a controller 10A according to the modification of the first embodiment.

FIG. 12 is a diagram explaining a calculation table indicating a relationship between a first motor pressure and an amount of wear according to the modification of the first embodiment.

FIG. 13 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to a second embodiment.

FIG. 14 is a flowchart explaining abnormality determination made for a slewing bearing by a controller 10B according to the second embodiment.

FIG. 15 is a diagram explaining a motor pressure and rotation angle data that change following a change of time according to the second embodiment.

FIG. 16 is a diagram explaining estimation of a wear position by a wear position estimation unit 22 according to the second embodiment.

FIG. 17 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to a third embodiment.

FIG. 18 is a diagram explaining a data table created by an aggregation unit 24 according to the third embodiment.

FIG. 19 is a diagram explaining a transition of an amount of wear according to the third embodiment.

FIG. 20 is a diagram explaining a transition of a wear range according to the third embodiment.

FIG. 21 is a diagram explaining a map of a wear position according to the third embodiment.

FIG. 22 is a diagram illustrating a swing circle according to another embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described with reference to the drawings. In the following description, the same components are denoted by the same reference signs. Their names and functions are the same. Therefore, detailed description thereof will not be repeated.

First Embodiment

Overall Configuration of Work Machine

FIG. 1 is a side view of a work machine according to a first embodiment.

FIG. 2 is a plan view of the work machine according to the first embodiment.

As illustrated in FIGS. 1 and 2, a hydraulic excavator 200 as the work machine includes a lower traveling body 210, a swing circle 220, and an upper rotating body 230. Hereinafter, a direction in which the gravity acts in a state where the work machine is installed on a horizontal plane is referred to as a “vertical direction”. In addition, a front side of an operator seat in a cab 231 described later is simply referred to as a “front side”, and a rear side thereof is simply referred to as a “rear side”.

The lower traveling body 210 includes a pair of left and right crawler belts 211 and 211. The crawler belts 211 and 211 are each driven by a hydraulic motor for traveling (not illustrated) to cause the hydraulic excavator 200 to travel.

A slewing bearing is a member for connecting the lower traveling body 210 and the upper rotating body 230 in a rotatable manner, and includes the swing circle 220 and a swing pinion 223.

The swing circle 220 includes an outer race 221 and an inner race 222.

The outer race 221 is fixed to the upper rotating body 230. The inner race 222 is supported by the lower traveling body 210, and has an annular shape centered at a rotation axis L extending in the vertical direction. The outer race 221 is an annular member coaxial with the inner race 222, and is disposed outside the inner race 222. The outer race 221 is supported to be rotatable relative to the inner race 222 about the rotation axis L. A rotation motor 239 configured to rotate the swing pinion 223 is fixed to the upper rotating body 230. When the swing pinion 223 transmits a rotational force to the inner race 222, the inner race side that is fixed to the lower traveling body installed on the ground and having a large frictional resistance force maintains a state of being stopped. The swing pinion 223 fixed to the outer race 221 side rotates because the frictional resistance force in the rotating direction is made small at the outer race 221 side by a rolling element 241. Specifically, the swing pinion 223 rotates relative to the inner race 222, and the outer race 221 rotates relative to the inner race 222 via the swing pinion 223 and the upper rotating body 230.

Because of being supported by the outer race 221, the upper rotating body 230 is disposed to be rotatable about the rotation axis L relative to the lower traveling body 210. The upper rotating body 230 includes the cab 231 and a work implement 232.

The cab 231 is disposed on the front left side of the upper rotating body 230 and is provided with an operator seat for the operator. The work implement 232 is provided to extend to the front side of the upper rotating body 230, and includes a boom 233, an arm 234, and a bucket 235. The work implement 232 performs various kinds of work such as excavation using the boom 233, the arm 234, and the bucket 235 driven by each of hydraulic cylinders (not illustrated).

A hydraulic pump 238 is driven by an engine 236. A hydraulic pressure generated by driving of the hydraulic pump 238 drives the rotation motor 239, the hydraulic motor for traveling, hydraulic cylinders, and the like.

Output of the rotation motor 239 is transmitted to the swing pinion 223 fastened to a rotation shaft of the rotation motor 239, thereby rotating the swing pinion 223. Then, the output of the rotation motor 239 is transmitted to the inner race 222 via internal teeth of the inner race 222 configured to engage with teeth of the swing pinion 223. With this, as described above, the swing pinion 223 rotates relative to the inner race 222, and the outer race 221 rotates relative to the inner race 222 via the swing pinion 223 and the upper rotating body 230.

FIG. 3 is a diagram explaining a main part of a rotating device according to the first embodiment. Referring to FIG. 3, the rotating device includes the rotation motor 239, the swing pinion 223, and the swing circle 220.

FIG. 4 is a diagram explaining the swing circle 220 according to the first embodiment.

An enlarged cross-sectional view of the swing circle 220 is illustrated in FIG. 4(A).

An external appearance of the swing circle 220 is illustrated in FIG. 4(B).

Referring to FIG. 4(A) and (B), the swing circle 220 includes the inner race 222, the outer race 221, and the rolling element 241.

The rolling element 241 is held and disposed in a rollable manner between the inner race 222 and the outer race 221.

The swing pinion 223 is disposed to engage with the internal teeth of the inner race 222. The outer race 221 rotates relative to the inner race 222 via the swing pinion 223 and the upper rotating body 230.

Configuration of Rotation System

FIG. 5 explains a general block diagram illustrating a configuration of a rotation system of the work machine according to the first embodiment.

As illustrated in FIG. 5, the rotation system of the work machine includes the engine 236, the hydraulic pump 238, a valve 240, the rotation motor 239, and the swing pinion 223.

The hydraulic pump 238 is driven by the engine 236.

Hydraulic pressure is supplied from the hydraulic pump 238 to the rotation motor 239 via the valve 240. The output of the rotation motor 239 is transmitted to the inner race 222 via the swing pinion 223. Then, the upper rotating body 230 rotates.

In the present example, there are provided a hydraulic pressure sensor 242 configured to measure a hydraulic pressure at an inlet (IN) side for supplying hydraulic oil to the rotation motor 239, and a hydraulic pressure sensor 244 configured to measure a hydraulic pressure at an outlet (OUT) side for discharging hydraulic oil from the rotation motor 239.

Sensor values (hydraulic pressure values) measured by the hydraulic pressure sensors 242 and 244 are output to a controller 10.

The controller 10 determines the state of the slewing bearing based on the hydraulic pressure value measured by at least one of the hydraulic pressure sensors 242 and 244.

Specifically, the controller 10 includes a wear determination unit 12, an acquisition unit 14, a notification unit 16, and an analysis unit 18.

The acquisition unit 14 acquires a hydraulic pressure value measured by at least one of the hydraulic pressure sensors 242 and 244.

The analysis unit 18 analyzes the hydraulic pressure value acquired by the acquisition unit. In the present example, as an example, the analysis unit 18 executes fast Fourier transform (FFT) processing. With this, frequency characteristics of the measured hydraulic pressure value can be acquired.

The wear determination unit 12 determines a degree of wear based on the frequency characteristics of the hydraulic pressure value having been analyzed by the analysis unit 18.

The notification unit 16 executes notification processing based on the determination result made by the wear determination unit 12.

FIG. 6 is a flowchart explaining abnormality determination made for the slewing bearing by the controller 10 according to the first embodiment.

Referring to FIG. 6, the acquisition unit 14 acquires data of hydraulic pressure values from the hydraulic pressure sensors 242, 244 (step S2).

The analysis unit 18 analyzes the data of hydraulic pressure values from the hydraulic pressure sensors 242, 244 acquired by the acquisition unit 14 (step S3). In the present example, the analysis unit 18 executes FFT processing as an example. With this, frequency characteristics of the hydraulic pressure value can be acquired.

Subsequently, the wear determination unit 12 compares the frequency characteristics of the hydraulic pressure value analyzed by the analysis unit 18 with normal data (step S4).

Subsequently, the wear determination unit 12 judges whether abnormality is present in the slewing bearing based on the comparison result (step S6).

When the wear determination unit 12 judges in step S6 that there is no abnormality in the slewing bearing (NO in step S6), the process returns to step S2 and the above-described pieces of processing are repeated.

On the other hand, when the wear determination unit 12 judges in step S6 that there is abnormality in the slewing bearing (YES in step S6), the process proceeds to step S8 and the wear determination unit 12 notifies the notification unit 16 of the presence of abnormality.

In step S8, the notification unit 16 executes notification processing based on the determination result from the wear determination unit 12. As the notification processing, any notification means may be used as long as the determination result can be delivered to the operator, such as issuing a request message for the replacement or turning on a lamp for requesting the replacement.

Then, the abnormality determination processing is ended (END).

FIG. 7 is a diagram explaining changes in motor pressures as hydraulic pressure values of the hydraulic pressure sensors 242, 244 and frequency characteristics in the slewing bearing at a normal time according to the first embodiment.

As an example, the hydraulic pressure at the inlet (IN) side for supplying the hydraulic oil to the rotation motor 239 is referred to as a first motor pressure, and the hydraulic pressure at the outlet (OUT) side for discharging the hydraulic oil from the rotation motor 239 is referred to as a second motor pressure.

Referring to FIG. 7(A), the upper side thereof is a diagram depicting the state of the first motor pressure of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239.

The lower side thereof is a diagram depicting the state of the second motor pressure of the hydraulic pressure sensor 244 provided at the output side of the rotation motor 239. As depicted in the diagrams, predetermined motor pressures are periodically measured at the input and output sides alternately.

Referring to FIG. 7(B), in this case, frequency characteristics with respect to the first motor pressure of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239 are depicted; the first motor pressure is depicted on the upper side of FIG. 7(A). As the frequency characteristics, a high state of the first motor pressure is detected in the vicinity of a frequency Q, but the first motor pressure is in a low state at other frequencies.

In the present example, although the frequency characteristics with respect to the first motor pressure, depicted on the upper side of FIG. 7(A), of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239 are described, frequency characteristics with respect to the second motor pressure of the hydraulic pressure sensor 244 provided at the output side of the rotation motor 239 are basically the same; the second motor pressure is depicted on the lower side of FIG. 7(A).

FIG. 8 is a diagram explaining changes in the first and second motor pressures as the hydraulic pressure values of the hydraulic pressure sensors 242, 244 and frequency characteristics in the slewing bearing at an abnormal time according to the first embodiment.

Referring to FIG. 8(A), the upper side thereof is a diagram depicting the state of the first motor pressure of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239.

The lower side thereof is a diagram depicting the state of the second motor pressure of the hydraulic pressure sensor 244 provided at the output side of the rotation motor 239.

As depicted in the diagrams, very small fluctuations are generated in the predetermined motor pressures, that is, the predetermined motor pressures do not have substantially constant values and thus are not in a flat state. This is caused by the occurrence of flaking (peeling) in the swing circle 220. For example, at least one of transfer surfaces of the outer race 221 and the inner race 222 is worn due to the contact with the rolling element 241, whereby flaking (peeling) occurs on the transfer surface.

Referring to FIG. 8(B), in this case, frequency characteristics with respect to the first motor pressure of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239 are depicted; the first motor pressure is depicted on the upper side of FIG. 8(A). As the frequency characteristics, a high state of the first motor pressure is detected at a frequency other than the vicinity of the frequency Q. The frequency at which the high state of the first motor pressure is detected is lower than the frequency Q.

In the present example, although the frequency characteristics with respect to the first motor pressure, depicted on the upper side of FIG. 8(A), of the hydraulic pressure sensor 242 provided at the input side of the rotation motor 239 are described, frequency characteristics with respect to the second motor pressure of the hydraulic pressure sensor 244 are basically the same; the second motor pressure is depicted on the lower side of FIG. 8(A).

FIG. 9 is a diagram explaining comparison determination of abnormality of the slewing bearing according to the first embodiment.

FIG. 9(A) schematically depicts frequency characteristics of the first motor pressure supplied to the rotation motor 239 configured to drive the slewing bearing at a normal time.

FIG. 9(B) schematically depicts frequency characteristics of the first motor pressure supplied to the rotation motor 239 configured to drive the slewing bearing at an abnormal time.

In the frequency characteristics at the abnormal time, a high first motor pressure is detected in a frequency band lower than the predetermined frequency Q as compared with the frequency characteristics at the normal time. As an example, a case is depicted in which a motor pressure p is detected as the high first motor pressure.

Specifically, the wear determination unit 12 can determine a wear state of the slewing bearing based on whether or not the first motor pressure higher than a predetermined threshold pr is detected.

In a scheme according to the first embodiment, it is possible to determine the wear state of the slewing bearing by analyzing the frequency characteristics of the first or second motor pressure supplied to the rotation motor 239 or discharged from the rotation motor 239.

A scheme in which a sensor is directly provided in a slewing bearing or the like and a determination is made by measuring a sensor value of the sensor is easily affected by disturbance, thereby making it difficult to determine a state with high accuracy. However, the scheme according to the first embodiment is a scheme in which the motor pressure at the input side or the output side of the rotation motor 239 serving as a drive device is measured to determine abnormality of the slewing bearing. Therefore, the scheme is unlikely to be affected by disturbance, so that the state of the slewing bearing can be determined with high accuracy.

Modification of First Embodiment

In a modification of the first embodiment, a scheme will be described in which the amount of wear of the slewing bearing is calculated and then the state of the slewing bearing is determined.

FIG. 10 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to the modification of the first embodiment.

Referring to FIG. 10, the rotation system of the work machine of the modification differs from the rotation system of the work machine of FIG. 5 in that the controller 10 is changed to a controller 10A. The controller 10A is different from the controller 10 in that a wear amount calculation unit 20 is further added.

The wear amount calculation unit 20 calculates the amount of wear of the slewing bearing based on the data of the first and second motor pressures (hydraulic pressure values) of the hydraulic pressure sensors 242, 244.

When high first and second motor pressures are detected in a frequency band lower than the predetermined frequency Q, the wear amount calculation unit 20 calculates the amount of wear of the slewing bearing with respect to the first and second motor pressures.

FIG. 11 is a flowchart explaining abnormality determination made for the slewing bearing by the controller 10A according to the modification of the first embodiment.

Referring to FIG. 11, the acquisition unit 14 acquires data of hydraulic pressure values from the hydraulic pressure sensors 242, 244 (step S2).

The analysis unit 18 analyzes the data of hydraulic pressure values from the hydraulic pressure sensors 242, 244 acquired by the acquisition unit 14 (step S3). In the present example, the analysis unit 18 executes FFT processing as an example. With this, frequency characteristics of the hydraulic pressure value can be acquired.

Subsequently, the wear amount calculation unit calculates the amount of wear of the slewing bearing (step S3A).

FIG. 12 is a diagram explaining a calculation table indicating a relationship between the first motor pressure and the amount of wear according to the modification of the first embodiment.

Referring to FIG. 12, a case in which the amount of wear linearly increases in proportion to the first motor pressure is depicted as the calculation table.

The wear amount calculation unit 20 calculates an amount of wear a with respect to a first motor pressure p, as an example, by using the calculation table.

Referring to FIG. 11 again, the wear determination unit 12 determines whether the wear level has reached a predetermined value (step S4A).

Subsequently, the wear determination unit 12 judges whether abnormality is present in the slewing bearing based on the determination result (step S6A).

Specifically, when the amount of wear has reached the predetermined value, it is judged that abnormality is present in the slewing bearing. The predetermined value may be changed as appropriate.

When the wear determination unit 12 judges in step S6A that there is no abnormality in the slewing bearing (NO in step S6A), the process returns to step S2 and the above-described pieces of processing are repeated.

On the other hand, when the wear determination unit 12 judges in step S6A that there is abnormality in the slewing bearing (YES in step S6A), the process proceeds to step S8 and the wear determination unit 12 notifies the notification unit 16 of the presence of abnormality.

In step S8, the notification unit 16 executes notification processing based on the determination result from the wear determination unit 12.

Then, the abnormality determination processing is ended (END).

In the scheme according to the modification of the first embodiment, it is possible to determine the wear state of the slewing bearing by analyzing the frequency characteristics of the first or second motor pressure supplied to the rotation motor 239 or discharged from the rotation motor 239 and calculating the amount of wear.

A scheme in which a sensor is directly provided in a slewing bearing or the like and a determination is made by measuring a sensor value of the sensor is easily affected by disturbance, thereby making it difficult to determine a state with high accuracy. However, the scheme according to the modification of the first embodiment is a scheme in which the motor pressure at the input side or the output side of the rotation motor 239 serving as a drive device is measured to calculate the amount of wear, thereby determining abnormality. A user can set, as a threshold, an amount of wear to be used as a management value, and can intuitively determine the wear state.

Second Embodiment

FIG. 13 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to a second embodiment.

Referring to FIG. 13, the rotation system of the work machine of the second embodiment differs from the rotation system of the work machine in FIG. 5 in that the controller 10 is changed to a controller 10B. The controller 10B is different from the controller 10 in that a wear position estimation unit 22 is further added. Furthermore, a rotation angle detection sensor 246 for detecting the rotation angle of the upper rotating body 230 is provided. The acquisition unit 14 of the controller 10B acquires rotation angle data of the upper rotating body 230 together with the data of hydraulic pressure values.

The wear position estimation unit 22 estimates a wear position of the slewing bearing based on the time and the data of the first and second motor pressures (hydraulic pressure values) of the hydraulic pressure sensors 242, 244, and the time and the rotation angle data of the rotation angle detection sensor 246.

FIG. 14 is a flowchart explaining abnormality determination made for the slewing bearing by the controller 10B according to the second embodiment.

Referring to FIG. 14, the acquisition unit 14 acquires the time and the data of hydraulic pressure values from the hydraulic pressure sensors 242 and 244 (step S2A).

The acquisition unit 14 acquires the time and the rotation angle data of the upper rotating body 230 from the rotation angle detection sensor 246 (step S2B).

The analysis unit 18 analyzes the time and the data of hydraulic pressure values from the hydraulic pressure sensors 242, 244 acquired by the acquisition unit 14 (step S3). In the present example, the analysis unit 18 executes FFT processing as an example. With this, frequency characteristics of the hydraulic pressure value can be acquired.

Subsequently, the wear determination unit 12 compares the frequency characteristics of the hydraulic pressure value analyzed by the analysis unit 18 with normal data (step S4).

Subsequently, the wear determination unit 12 judges whether abnormality is present in the slewing bearing based on the comparison result (step S6).

When the wear determination unit 12 judges in step S6 that there is no abnormality in the slewing bearing (NO in step S6), the process returns to step S2 and the above-described pieces of processing are repeated.

On the other hand, when the wear determination unit 12 judges in step S6 that there is abnormality in the slewing bearing (YES in step S6), the process proceeds to step S7.

In step S7, the wear position estimation unit 22 estimates a position at which there exists abnormality in the slewing bearing. Subsequently, the estimated wear position is notified to the notification unit 16.

In step S8, the notification unit 16 executes notification processing for telling the presence of abnormality together with the wear position estimated by the wear position estimation unit 22.

Then, the abnormality determination processing is ended (END).

FIG. 15 is a diagram explaining a motor pressure and rotation angle data that change following a change of time according to the second embodiment.

Referring to FIG. 15(A), a case is depicted in which as the time changes from time t1 to time tn, a motor pressure changes in the sequence of p1, p2, p3, . . . , pn.

Referring to FIG. 15(B), a case is depicted in which as the time changes from time t1 to time tn, a rotation angle changes in the sequence of θ1, θ2, . . . , θn.

It is possible to estimate a wear position from the relationship between the motor pressures and the rotation angles associated with the time.

FIG. 16 is a diagram explaining the estimation of a wear position by the wear position estimation unit 22 according to the second embodiment.

Referring to FIG. 16(A), a change in the first motor pressure (hydraulic pressure value) of the hydraulic pressure sensor 242 is depicted. Specifically, when wear occurs in the slewing bearing, amplitude fluctuations occur in comparison with the normal time. The wear determination unit 12 determines the wear state of the slewing bearing by detecting a higher motor pressure than the predetermined threshold pr as described in the first embodiment. Specifically, the wear determination unit 12 determines the wear state of the slewing bearing in a section where the amplitude fluctuation is large.

Referring to FIG. 16(B), a change in the rotation angle of the upper rotating body 230 of the work machine is depicted. The wear position estimation unit 22 extracts the rotation angles respectively corresponding to the first time when the wear state determination is made and the last time when the wear state determination is made by the wear determination unit 12.

As an example, the wear position estimation unit 22 extracts the rotation angle θ1 corresponding to the first time t1, at which the wear state determination is made, and the rotation angle θ2 corresponding to the last time t2, at which the wear state determination is made. A section between the rotation angles θ1 and θ2 is a wear range.

As an example, a range from θ1 (10°) to θ2 (20°) is indicated as the wear range.

A Y-axis in FIG. 16(B) represents a rotation angle (deg). In this case, the “rotation angle” refers to a relative rotation angle of the upper rotating body 230 (outer circle support) with respect to the lower traveling body 210 (inner circle support).

FIG. 16(C) is a diagram conceptually explaining the wear position of the swing circle. As an example, a case is depicted in which 360° is divided into eight regions of rotation positions 1 to 8. The rotation position and the wear range illustrated in FIG. 16(C) indicate azimuth angles with the front side as a reference direction in a state where the front sides of the lower traveling body 210 and the work implement 232 are aligned (a state in which the relative positions of the outer circle and the inner circle are aligned).

In the present example, in the case where a wear state is detected between the rotation angles θ1 and θ2, it is indicated that at least one of the outer circle and the inner circle at the same azimuth angle position is worn when the relative positions of the lower traveling body 210 and the work implement 232 are matched as illustrated in FIG. 16(C).

For example, the notification unit 16 may notify the wear range or the rotation position (“1 (0-45 deg)”) where the wear range is located as the estimated wear position. Alternatively, the estimated wear position may be notified by displaying the diagram of FIG. 16(C).

As described in the modification of the first embodiment, a scheme may be employed in which the amount of wear is calculated based on the motor pressures and the abnormality of the slewing bearing is determined. In the present example, the scheme of estimating the wear range and the wear position using the time information has been described, but the present disclosure is not limited thereto, and the wear position may be estimated by acquiring the motor pressures and the rotation angles in association with each other without using the time information.

With the scheme according to the second embodiment, a maintenance position can be easily specified by estimating the wear position.

Third Embodiment

In the second embodiment, the scheme of estimating a wear position in accordance with the motor pressure p and the rotation angle θ associated with the time has been described.

A data table can be created by accumulating the above-mentioned data.

FIG. 17 explains a general block diagram illustrating a configuration of a rotation system of a work machine according to a third embodiment.

Referring to FIG. 17, the rotation system of the work machine of the present embodiment differs from the rotation system of the work machine in FIG. 5 in that the controller 10 is changed to a controller 10C. The controller 10C is different from the controller 10 in that a wear amount calculation unit 20, a wear position estimation unit 22, and an aggregation unit 24 are further added.

The aggregation unit 24 aggregates data and presents an aggregation result.

FIG. 18 is a diagram explaining a data table created by the aggregation unit 24 according to the third embodiment.

Referring to FIG. 18, as an example, a case in which 360° is divided into n regions is depicted.

An amount of wear and a wear range corresponding to each of the divided n regions are depicted.

Specifically, the amount of wear is calculated based on the motor pressures when the wear state is detected.

The wear range can be calculated in accordance with the rotation angles respectively corresponding to the first time when the wear state is determined and the last time when the wear state is determined.

As an example, an amount of wear “α1” and a wear range “β1” are registered corresponding to a rotation position “1”. An amount of wear “α2” and a wear range “β2” are registered corresponding to a rotation position “2”. An amount of wear “α3” and a wear range “β3” are registered corresponding to a rotation position “3”.

The aggregation unit 24 checks as needed whether an amount of wear that is larger than the recorded amount of wear is measured in each rotation position as a real-time situation; when such amount of wear is measured, the aggregation unit 24 overwrites and updates the amount of wear corresponding to the above rotation position.

The aggregation unit 24 may separately store the data table overwritten and updated, at predetermined time intervals. As an example, the data table overwritten and updated may be separately stored, every 8 hours, every 12 hours, every 20 hours, or every day.

Further, the data table may be separately stored for each date. For example, the overwritten and updated data table at 24:00 on January 1 is stored as a data table associated with January 1. Similarly, the overwritten and updated data table at 24:00 on January 2 is stored as a data table associated with January 2. The overwritten and updated data table at 24:00 on January 3 is stored as a data table associated with January 3.

FIG. 19 is a diagram explaining a transition of an amount of wear according to the third embodiment.

Referring to FIG. 19, in the present example, the maximum value of the amount of wear of each day is extracted and graphed as time-series data with regard to the data table aggregated by the aggregation unit 24. The horizontal axis represents time and the vertical axis represents a wear level.

The wear level in the present example indicates the ratio of an amount of wear a to a wear limit amax.

FIG. 20 is a diagram explaining a transition of a wear range according to the third embodiment.

Referring to FIG. 20, in the present example, the aggregated value of the wear range of each day is extracted and graphed as time-series data regarding the data table aggregated by the aggregation unit 24. The horizontal axis represents time and the vertical axis represents a wear level.

The wear level in the present example indicates the ratio of a total wear range B to the maximum wear range 360°.

FIG. 21 is a diagram explaining a map of a wear position according to the third embodiment.

Referring to FIG. 21, in the present example, 360° is divided into eight regions of rotation positions 1 to 8, and then the amount of wear corresponding to each rotation position is mapped.

The amount of wear at each rotation position is extracted and graphed with regard to the data table aggregated by the aggregation unit 24. The horizontal axis represents the rotation position and the vertical axis represents the wear level.

The wear level in the present example indicates the ratio of the amount of wear a to the wear limit amax.

The wear position and the wear level can be easily grasped by the map of the wear position.

In the present example, although the case in which the data table is created by converting the motor pressures into the amounts of wear is described, the data table may be created using the motor pressures.

In FIG. 19, the maximum value is extracted from the amounts of wear at a plurality of the rotation positions and graphed as time-series data, but the amount of wear at one rotation position optionally selected may be graphed as time-series data. Alternatively, the maximum value may be extracted from the plurality of rotation positions optionally selected, and graphed as time-series data.

It is also possible to make a maintenance plan for the slewing bearing based on the transition of the amount of wear discussed above.

For example, the controller 10C can estimate a period when the slewing bearing becomes abnormal in accordance with the changes in wear level of FIGS. 19 and 20.

The controller 10C may notify the operator of the estimated period, as notification processing.

In the above-described embodiment, the hydraulic excavator is given as an example of the work machine, but the work machine is not limited to the hydraulic excavator; the present disclosure is applicable to other types of work machines including a slewing bearing, such as a crane and a slewing dump truck.

In the present example, the case in which the data of hydraulic pressure values is acquired from both of the hydraulic pressure sensors 242, 244 has been described. However, the data of hydraulic pressure values may be acquired from any one of the hydraulic pressure sensors, and the state of the slewing bearing may be determined based on the data of hydraulic pressure values of the one hydraulic pressure sensor. Alternatively, the data of hydraulic pressure values may be acquired from both of the hydraulic pressure sensors 242, 244, and the state of the slewing bearing may be determined based on difference data of the hydraulic pressure values.

Further, the controller may adjust control parameters of the work machine based on the calculated amount of wear. Specifically, by feeding back the calculated amount of wear to an automatic control system, an information and communication technology (ICT) can be constructed with higher accuracy. Specifically, a bucket blade tip position may be corrected based on the calculated amount of wear.

In addition, the controller described above may be connected to a network (not illustrated) and may execute data communication processing with an external apparatus (e.g., a server).

At least some of the functions executed in the controller may be distributed to and executed by a plurality of apparatuses capable of communications via a network (a wide area network and/or a local network). Specifically, at least some of the various functions executed in the controller may be executed by the server.

In a case where the notification unit is provided in the server, a message that requests the replacement may be issued to an information processing apparatus provided to be able to communicate with the server, or information related to the replacement time may be notified.

In the above description, the scheme in which abnormality of the slewing bearing is determined based on input/output data (sensing data) of the hydraulic rotation motor as a drive device for driving the slewing bearing has been explained. However, without being limited to the hydraulic rotation motor, the abnormality of the slewing bearing may be determined based on input/output data of an electromotive rotation motor. Specifically, in the case of the electromotive rotation motor, a current or a voltage may be detected, and abnormality of the slewing bearing may be determined based on the data of the current or voltage in accordance with a similar scheme.

In the above description, the scheme of determining abnormality of the swing circle 220 serving as the slewing bearing of the hydraulic excavator as the work machine has been explained. However, the present disclosure is not limited to the swing circle 220, and is similarly applicable to other mechanisms. For example, the present disclosure is also similarly applicable to a gear of a device having a configuration of a hydraulic motor and a gear box, a mechanism such as a bearing combined with the above-mentioned gear, a speed reducer for reducing the speed of rotation of the rotation motor 239, and the like.

Further, the swing circle 220 is not limited to that illustrated in FIG. 4, and the present disclosure is similarly applicable to other swing circles.

FIG. 22 is a diagram illustrating a swing circle according to another embodiment.

A swing circle 220A used in a large work machine will be described with reference to FIG. 22. The swing circle 220A includes an inner race 222, an upper outer race 221A, a lower outer race 221B, and a roller 241#. The roller 241# is provided in three regions. Specifically, the outer race 221 is divided into the upper outer race 221A and the lower outer race 221B.

The roller 241# provided on the upper side is disposed between the inner race 222 and the upper outer race 221A in a rollable manner. The roller 241# provided on a lateral side is disposed between the inner race 222 and the upper outer race 221A in a rollable manner. The roller 241# provided on the lower side is disposed between the inner race 222 and the lower outer race 221B in a rollable manner.

The configuration of the present application can be similarly applied to the swing circle 220A of the configuration described above.

Supplementary Note

The above-described embodiments include technical ideas as follows.

Supplementary Note 1

A work machine including:

• • a slewing bearing;
  • a drive device (239) configured to drive the slewing bearing;
  • detection units (242, 244) configured to detect a state of at least one of input to the drive device and output from the drive device; and
  • a determination unit (12) configured to determine a state of the slewing bearing based on a detection value detected by the detection units.

Supplementary Note 2

The work machine according to supplementary note 1, wherein

• • the determination unit determines the state of the slewing bearing based on a result of comparison between the detection value and a value at a normal time.

Supplementary Note 3

The work machine according to supplementary note 1 or 2, wherein

• • the determination unit includes a wear amount calculation unit (20) configured to calculate an amount of wear of the slewing bearing based on the detection value.

Supplementary Note 4

The work machine according to supplementary note 3, wherein

• • the determination unit further includes a notification unit (16) configured to perform notification when the amount of wear is equal to or greater than a threshold.

Supplementary Note 5

The work machine according to any one of supplementary notes 1 to 4, further including:

• • a rotation angle detection unit (246) configured to detect a rotation angle, wherein
  • the determination unit includes a position estimation unit (22) configured to estimate a wear position of the slewing bearing based on the rotation angle at a detection time point of the detection value.

Supplementary Note 6

A method of controlling a work machine, the method including:

• • a step of driving a slewing bearing;
  • a step (S2) of detecting a state of at least one of input to a drive device configured to drive the slewing bearing and output from the drive device; and
  • steps (S3 to S6) of determining a state of the slewing bearing based on a detected detection value.

Supplementary Note 7

A control system of a work machine, the system including:

• • a slewing bearing;
  • a drive device (239) configured to drive the slewing bearing;
  • detection units (242, 244) configured to detect a state of at least one of input to the drive device and output from the drive device; and
  • a determination unit (12) configured to determine a state of the slewing bearing based on a detection value detected by the detection units.

The embodiments of the present disclosure have been described thus far, but it should be noted that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present disclosure is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

REFERENCE SIGNS LIST

• • 10, 10A, 10B Controller, 12 Wear determination unit, 14 Acquisition unit, 16 Notification unit, 18 Analysis unit, 20 Wear amount calculation unit, 22 Wear position estimation unit, 200 Hydraulic excavator, 210 Lower traveling body, 211 Crawler belt, 220 Swing circle, 221 Outer race, 222 inner race, 223 Swing pinion, 230 Upper rotating body, 231 Cab, 232 Work implement, 233 Boom, 234 Arm, 235 Bucket, 236 Engine, 238 Hydraulic pump, 239 Rotation motor, 240 Valve, 241 Rolling element, 242, 244 Hydraulic pressure sensor.