System and method for evaluating abrasion state of sliding bearing

Abstract

To accurately evaluate an abrasion state of a sliding bearing.SOLUTION: A system is a system for evaluating an abrasion state of a sliding bearing in a machine including a rotor, the sliding bearing and a load sensor. The sliding bearing supports the rotor. The sliding bearing includes a first layer in contact with the rotor and a second layer laminated on the first layer. The load sensor detects load data relating to a load on the sliding bearing. The system according to the present aspect includes an abrasion amount calculation unit, an abrasion degree calculation unit and an abrasion state evaluation unit. The abrasion amount calculation unit calculates an abrasion amount of the sliding bearing on the basis of the load data. The abrasion degree calculation unit calculates an abrasion degree on the abrasion amount. The abrasion degree relates to an area of the second layer exposed by abrasion of the first layer. The abrasion state evaluation unit evaluates the abrasion state of the sliding bearing on the basis of the abrasion degree.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a system and method for assessing the wear condition of a plain bearing. [Background technology]

[0002] In machines equipped with a rotating body, the rotating body is supported by bearings. The bearings wear as the operating time of the machine increases. If the bearing wear progresses excessively, problems such as seizure occur. For this reason, there is a known technique for evaluating the wear state of a bearing based on the amount of wear of the bearing.

[0003] For example, in Patent Document 1, a vehicle control device calculates the cumulative load of a bearing based on the torque, rotation speed, and operating time of the engine.The vehicle control device estimates the amount of wear of the bearing based on the cumulative load of the bearing.The vehicle control device determines the levels of noise and vibration caused by the wear of the bearing based on the amount of wear of the bearing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-015063 A Summary of the Invention [Problem to be solved by the invention]

[0005] The above vehicle control device evaluates the wear state of a bearing based on the amount of wear of the bearing. However, there is a demand for a more accurate evaluation of the wear state of a plain bearing. An object of the present disclosure is to accurately evaluate the wear state of a plain bearing. [Means for solving the problem]

[0006] A system according to one aspect of the present disclosure is a system for evaluating a wear state of a plain bearing in a machine including a rotating body, a plain bearing, and a load sensor. The plain bearing supports the rotating body. The plain bearing includes a first layer in contact with the rotating body and a second layer laminated on the first layer. The load sensor detects load data related to a load on the plain bearing. The system according to this aspect includes a wear amount calculation unit, a wear degree calculation unit, and a wear state evaluation unit. The wear amount calculation unit calculates the wear amount of the plain bearing based on the load data. The wear degree calculation unit calculates the wear degree based on the wear amount. The wear degree relates to an area of ​​the second layer exposed due to wear of the first layer. The wear state evaluation unit evaluates the wear state of the plain bearing based on the wear degree.

[0007] A method according to another aspect of the present disclosure is a method executed by a computer for evaluating a wear state of a plain bearing in a machine including a rotating body, a plain bearing, and a load sensor. The plain bearing supports the rotating body. The plain bearing includes a first layer in contact with the rotating body and a second layer laminated on the first layer. The load sensor detects load data related to a load on the plain bearing. The method according to this aspect includes calculating an amount of wear of the plain bearing based on the load data, calculating a degree of wear related to an area of ​​the second layer exposed due to wear of the first layer based on the amount of wear, and evaluating the wear state of the plain bearing based on the degree of wear. Effect of the Invention

[0008] According to the present disclosure, the wear state of a plain bearing is evaluated based on the degree of wear. The degree of wear relates to the area of ​​the second layer that is exposed as a result of wear of the first layer in the plain bearing. When wear of the first layer in the plain bearing progresses and the second layer becomes exposed, there is an increased concern that the plain bearing will suffer from a defect such as seizure. The concern that this defect will occur is more closely related to the exposed area of ​​the second layer than to the amount of wear. Therefore, the wear state of the plain bearing can be accurately evaluated based on the degree of wear related to the exposed area of ​​the second layer. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a system and a machine according to an embodiment; [Diagram 2] FIG. 2 is a perspective view of a rotating body and a plain bearing of the engine. [Diagram 3] 3 is an enlarged cross-sectional view taken along line III-III of the bearing metal of the plain bearing in FIG. 2. [Figure 4] 4 is a flowchart showing a process for evaluating the wear state of a sliding bearing. [Diagram 5] FIG. 2 is a diagram showing the inner surface of a part of a sliding bearing in which wear has progressed. [Figure 6] 1 is a graph showing the relationship between wear amount and wear degree according to a Gompertz function. [Figure 7] FIG. 13 is a diagram showing a bush of a work machine as another example of a plain bearing. [Figure 8] FIG. 13 is a diagram showing a support part of a hydraulic pump as another example of a plain bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a system for evaluating the wear state of a plain bearing of a machine 1 according to an embodiment. The machine 1 is, for example, a construction machine such as a hydraulic excavator, a bulldozer, a wheel loader, a grader, or a dump truck. As shown in Fig. 1, the machine 1 includes an engine 11, a transmission 12, and a traveling device 13.

[0011] The engine 11 is, for example, a diesel engine. A fuel injector 14 and a turbocharger 15 are connected to the engine 11. The fuel injector 14 injects fuel into the engine 11. The turbocharger 15 includes, for example, a turbine. The turbocharger 15 compresses intake air and supplies it to the engine 11. The engine 11 includes a rotating body 16. The rotating body 16 is a crankshaft. The engine 11 drives the rotating body 16 to rotate.

[0012] The transmission 12 is connected to the engine 11 via the PTO 12. The transmission 12 includes, for example, a plurality of speed change gears. Alternatively, the transmission 12 may be another transmission such as a hydrostatic transmission (HST) or a hydro mechanical transmission (HMT). The transmission 12 transmits the driving force from the engine 11 to the traveling device 13. The traveling device 13 includes, for example, a track. Alternatively, the traveling device 13 may include wheels and tires. The traveling device 13 is driven by the driving force of the engine 11 transmitted from the transmission 12. This causes the machine 1 to travel.

[0013] The machine 1 includes a hydraulic pump 17 and a hydraulic actuator 18. The hydraulic pump 17 is connected to the engine 11 via a PTO 19. The hydraulic pump 17 is driven by the engine 11 to discharge hydraulic oil. The hydraulic actuator 18 is driven by the hydraulic oil from the hydraulic pump 17. The hydraulic actuator 18 is, for example, a hydraulic cylinder, and operates a work implement 20. The work implement 20 includes, for example, a blade or a bucket.

[0014] 2 is a perspective view of the rotating body 16 and plain bearing 21 of the engine 11. The plain bearing 21 supports the rotating body 16 in the engine 11. The plain bearing 21 includes a plurality of bearing metals 22A-22G, 23A-23G. The plurality of bearing metals 22A-22G, 23A-23G each slidably supports the rotating body 16.

[0015] FIG. 3 is an enlarged cross-sectional view of the bearing metal 22A in FIG. 2 taken along line III-III. As shown in FIG. 3, the bearing metal 22A includes a first layer 24, a second layer 25, and a third layer 26. The first layer 24 is located on the innermost side of the bearing metal 22A. The first layer 24 contacts the rotating body 16. The first layer 24 is made of a sliding material such as Pb. The second layer 25 is laminated on the first layer 24 on the outer diameter side of the first layer 24. The second layer 25 is made of a sliding material different from the first layer 24, such as Cu. The third layer 26 is laminated on the second layer 25 on the outer diameter side of the second layer 25. The third layer 26 is made of a material having a higher hardness than the first layer 24 and the second layer 25, such as Fe. The other bearing metals 22B-22G and 23A-23G have the same configuration as the bearing metal 22A.

[0016] As shown in Fig. 1, the machine 1 includes a load sensor 30. The load sensor 30 detects load data related to the load on the sliding bearing 21. The load sensor 30 includes a boost pressure sensor 31 and an oil temperature sensor 32. The boost pressure sensor 31 detects the boost pressure of the turbocharger 15. The oil temperature sensor 32 detects the engine oil temperature. The machine 1 also includes an engine rotation speed sensor 33. The engine rotation speed sensor 33 detects the engine rotation speed of the engine 11.

[0017] The machine 1 includes a controller 34. The controller 34 controls the machine 1. The controller 34 includes a storage device 35 and a processor 36. The storage device 35 includes memories such as RAM and ROM. The storage device 35 may include storage such as an HDD or SSD. The storage device 35 stores programs and data for controlling the machine 1. The processor 36 is, for example, a CPU. The processor 36 executes processing for controlling the machine 1 in accordance with the programs and data.

[0018] The controller 34 obtains the engine rotation speed from the engine rotation speed sensor 33. The controller 34 obtains the boost pressure of the turbocharger 15 from the boost pressure sensor 31. The controller 34 obtains the engine oil temperature from the oil temperature sensor 32.

[0019] The controller 34 controls the amount of fuel injected from the fuel injector 14, thereby controlling the engine rotation speed. The controller 34 switches the gear ratio of the transmission 12 in accordance with the vehicle speed or the engine rotation speed. The controller 34 controls the discharge capacity of the hydraulic pump 17, thereby controlling the operation of the work machine 20.

[0020] The machine 1 includes a communication device 37. The communication device 37 is communicatively connected to the controller 34. The communication device 37 communicates with a server 40 outside the machine 1 via wireless communication. The server 40 monitors the state of the machine 1 remotely.

[0021] The server 40 includes a storage device 41 and a processor 42. The storage device 41 includes memories such as RAM and ROM. The storage device 41 may include storage such as an HDD or SSD. The storage device 41 stores programs and data for monitoring the state of the machine 1. The processor 42 is, for example, a CPU. The processor 42 executes processing for monitoring the state of the machine 1 in accordance with the programs and data.

[0022] The controller 34 of the machine 1 transmits machine data to the server 40 via the communication device 37. The machine data includes load data, engine speed, and operating time. The load data includes the above-mentioned boost pressure and engine oil temperature. The load data also includes fuel efficiency. The fuel efficiency indicates the amount of fuel consumed per unit time. For example, the controller 34 calculates and records the fuel efficiency based on a command value to the fuel injector 14. The operating time is, for example, an integrated value of the time during which the engine 11 is driven. The controller 34 counts and records the operating time.

[0023] The machine 1 samples the above-mentioned data at predetermined sampling intervals and stores the data in the storage device 35 as machine data. The machine 1 transmits the stored machine data to the server 40. The server 40 evaluates the degree of wear of the plain bearing 21 based on the received machine data. The process performed by the server 40 to evaluate the degree of wear of the plain bearing 21 will be described below.

[0024] 1, the server 40 includes a data receiving unit 43, a wear amount calculation unit 44, a wear degree calculation unit 45, and a wear state evaluation unit 46. The data receiving unit 43, the wear amount calculation unit 44, the wear degree calculation unit 45, and the wear state evaluation unit 46 are realized by the processor 42 of the server 40.

[0025] Fig. 4 is a flowchart showing a process for evaluating the wear state of the plain bearing 21. As shown in Fig. 4, in step S101, the data receiving unit 43 receives machine data. The data receiving unit 43 receives the above-mentioned machine data from the controller 34 of the machine 1.

[0026] In step S102, the wear amount calculation unit 44 calculates the wear amount of the plain bearing 21. The wear amount is indicated by, for example, weight. The wear amount calculation unit 44 calculates the accumulated wear amount Wt up to time t based on the load data by the following formula (1). TIFF2025030293000002.tif10142K×P(i)×V(i) indicates the amount of wear per unit time. K is the specific wear rate, and is a constant determined by the combination of the materials of the metals that rub against each other. V(i) is the average engine rotation speed, and indicates the sliding speed. P(i) is the surface pressure applied to the sliding bearing 21, and is expressed by the following formula (2). P(i) = Maximum boost pressure [kPa] × Average fuel consumption [L / H] × Maximum engine oil temperature [℃] (2) The wear amount calculation unit 44 determines the maximum boost pressure, the average fuel consumption, the maximum engine oil temperature, and the average engine speed from the load data and the engine speed during a predetermined period of time.

[0027] In step S103, wear degree calculation unit 45 calculates the wear degree. The wear degree relates to the area of ​​the second layer 25 that is exposed as a result of the first layer 24 wearing away. Fig. 5 is a diagram showing the inner surface of a part of sliding bearing 21 where wear has progressed. As shown in Fig. 5, as wear progresses in sliding bearing 21, the first layer 24 wears away, exposing a part of the second layer 25. The wear degree indicates the area of ​​this exposed part of the second layer 25.

[0028] The wear degree calculation unit 45 calculates the wear degree based on the accumulated wear amount. In detail, the wear degree calculation unit 45 converts the accumulated wear amount into the wear degree by the Gompertz function. The Gompertz function is a type of function that indicates a growth curve as shown in FIG. 6, and has an inflection point. In FIG. 6, the horizontal axis indicates the standardized accumulated wear amount, and the vertical axis indicates the wear degree. The Gompertz function is expressed by the following formula (3). TIFF2025030293000003.tif11142a, b, and c are constants that are calculated from the actual wear amount and wear degree data and stored in the storage device 41. The wear degree calculation unit 45 converts the accumulated wear amount into a wear degree by applying this Gompertz function to the accumulated wear degree. That is, the wear degree Z(t) is expressed by the following formula (4). TIFF2025030293000004.tif10142 In step S104, the wear state evaluation unit 46 evaluates the wear state of the plain bearing 21 based on the degree of wear. For example, when the degree of wear is equal to or greater than a threshold value, the wear state evaluation unit 46 determines that the plain bearing 21 needs to be replaced. When the wear state evaluation unit 46 determines that the plain bearing 21 needs to be replaced, it displays a notice on the display of the machine 1 to prompt the user to replace the plain bearing 21. Alternatively, when the wear state evaluation unit 46 determines that the plain bearing 21 needs to be replaced, it may transmit a notice to the computer of the user of the machine 1 to prompt the user to replace the plain bearing 21.

[0029] According to the system according to the present embodiment described above, the wear state of the plain bearing 21 is evaluated based on the degree of wear. The degree of wear relates to the area of ​​the second layer 25 that is exposed as a result of wear of the first layer 24 in the plain bearing 21. When wear of the first layer 24 in the plain bearing 21 progresses and the second layer 25 becomes exposed, there is an increased concern that the plain bearing 21 will suffer from a defect such as seizure. The concern that this defect will occur is more closely related to the exposed area of ​​the second layer 25 than to the amount of wear. Therefore, the wear state of the plain bearing 21 can be accurately evaluated based on the degree of wear related to the exposed area of ​​the second layer 25.

[0030] Furthermore, the amount of wear is converted into the degree of wear by the Gompertz function. The exposed area of ​​the second layer 25 does not increase at a constant rate like the amount of wear, but increases with an inflection point like a growth curve such as the Gompertz function. Therefore, by converting the amount of wear into the degree of wear by the Gompertz function, the degree of wear can be calculated with high accuracy.

[0031] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0032] The structure of the plain bearing is not limited to that of the above embodiment and may be modified. For example, the plain bearing may be formed integrally instead of being made of a plurality of bearing metals. The number of layers of the plain bearing is not limited to three. The number of layers of the plain bearing may be two or more than three.

[0033] The above-described process for evaluating the wear state may be executed by the controller 34 of the machine 1. The process for evaluating the wear state may be executed in a distributed manner by a plurality of computers. For example, the process for evaluating the wear state may be executed in a distributed manner by the controller 34 of the machine 1 and the server 40.

[0034] In the above embodiment, the wear amount calculation unit 44 calculates the surface pressure applied to the plain bearing 21 based on the boost pressure, fuel efficiency, and engine oil temperature. However, the wear amount calculation unit 44 may calculate the surface pressure applied to the plain bearing 21 based on other data. For example, the wear amount calculation unit 44 may calculate the surface pressure applied to the plain bearing 21 based on the output torque of the engine 11, the combustion pressure, the rotation speed of the turbocharger 15, or the exhaust temperature.

[0035] In the above embodiment, the system evaluates the wear state of the plain bearing 21 for the crankshaft of the engine 11. However, the system may evaluate the wear state of a plain bearing for a rotating body other than the engine 11. For example, the system may evaluate the wear state of a plain bearing for a rotating body of the transmission 12.

[0036] 7, the rotating body may be the work machine 20, and the sliding bearing may be bushes 51, 52 attached to the work machine 20. The bushes 51, 52 support a hydraulic cylinder attached to the work machine 20. In this case, the wear amount calculation unit 44 may calculate the surface pressure acting on the bushes based on the head pressure or bottom pressure of the hydraulic cylinder. The wear amount calculation unit 44 may obtain the rotation speed of the work machine 20 as the sliding speed.

[0037] 8, the rotating body may be gears 62, 63 of a hydraulic pump 60, and the sliding bearing may be a support part 61 that supports the gears 62, 63. In this case, the wear amount calculation unit 44 may calculate the surface pressure applied to the support part 61 based on the pump pressure of the hydraulic pump 60. The wear amount calculation unit 44 may obtain the rotation speed of the hydraulic pump 60 as the sliding speed.

[0038] The server 40 may acquire actual data on the amount of wear and the degree of wear. The server 40 may learn the constants a, b, and c based on the acquired actual data, and update the constants a, b, and c for each model of the machine 1.

[0039] The function for converting the amount of wear into the degree of wear is not limited to the Gompertz function, but may be another function. For example, the wear degree calculation unit 45 may convert the amount of wear into the degree of wear by another function, such as a Sigmoid function or a Logistic function. The degree of wear is not limited to the exposed area of ​​the second layer 25 itself, but may be another parameter that changes depending on the exposed area. [Industrial Applicability]

[0040] According to the present disclosure, the wear state of a sliding bearing can be evaluated with high accuracy. [Explanation of symbols]

[0041] 1: machine, 11: engine, 16: rotating body, 21: plain bearing, 24: first layer, 25: second layer, 30: load sensor, 33: engine rotation speed sensor, 44: wear amount calculation unit, 45: wear degree calculation unit, 46: wear state evaluation unit

Claims

1. A system for evaluating a wear state of a plain bearing in a machine including a rotating body, a plain bearing that includes a first layer in contact with the rotating body and a second layer laminated on the first layer and supports the rotating body, and a load sensor that detects load data related to a load on the plain bearing, comprising: a wear amount calculation unit that calculates a wear amount of the plain bearing based on the load data; a wear degree calculation unit that calculates a wear degree relating to an area of ​​the second layer that is exposed due to the wear of the first layer based on the amount of wear; a wear state evaluation unit that evaluates a wear state of the plain bearing based on the wear degree; A system comprising:

2. The wear amount calculation unit Calculating the amount of wear of the sliding bearing per unit time based on the load data; Calculate the cumulative wear amount based on the wear amount each time, The wear degree calculation unit calculates the wear degree based on the accumulated wear amount. The system of claim 1 .

3. The wear degree calculation unit calculates the wear degree based on the wear amount using a predetermined function indicating a growth curve. The system of claim 1 .

4. The machine further includes an engine that rotates and drives the rotating body. The load data includes a boost pressure, a fuel consumption, and an engine oil temperature of the engine. The wear amount calculation unit Calculating a surface pressure applied to the sliding bearing based on the boost pressure, the fuel efficiency, and the engine oil temperature; Calculating the amount of wear of the sliding bearing based on the surface pressure. The system of claim 1 .

5. The machine further includes an engine speed sensor for detecting an engine speed of the engine; The wear amount calculation unit calculates the wear amount of the sliding bearing based on the surface pressure applied to the bearing and the engine rotation speed. The system of claim 4.

6. A method for evaluating a wear state of a plain bearing in a machine including a rotating body, a plain bearing that supports the rotating body and includes a first layer in contact with the rotating body and a second layer laminated on the first layer, and a load sensor that detects load data related to a load on the plain bearing, the method comprising: Calculating the amount of wear of the sliding bearing based on the load data; calculating a degree of wear related to an area of ​​the second layer that is exposed due to the wear of the first layer based on the amount of wear; Evaluating a wear state of the plain bearing based on the degree of wear; A method for providing the above.

7. Calculating the amount of wear of the sliding bearing per unit time based on the load data; and Calculating a cumulative wear amount based on the each-time wear amount; Calculating the degree of wear based on the accumulated wear amount; The method of claim 6 comprising:

8. Calculating the degree of wear based on the amount of wear using a predetermined function indicating a growth curve. The method according to claim 6.

9. The machine further includes an engine that rotates and drives the rotating body. The load data includes a boost pressure, a fuel consumption, and an engine oil temperature of the engine. Calculating a surface pressure applied to the sliding bearing based on the boost pressure, the fuel efficiency, and the engine oil temperature; Calculating the amount of wear of the sliding bearing based on the surface pressure; The method of claim 6 comprising:

10. The machine further includes an engine speed sensor for detecting an engine speed of the engine; Calculating the amount of wear of the sliding bearing based on the surface pressure applied to the bearing and the engine rotation speed; The method of claim 9 comprising:

Images