Work machine diagnostic system and work machine diagnostic method

Abstract

To identify abnormal hydraulic equipment.SOLUTION: A diagnostic system for a work machine equipped with a hydraulic system having a hydraulic pump, a work implement cylinder, and a control valve that controls a flow rate and a direction of hydraulic oil supplied from the hydraulic pump to the work implement cylinder includes: a condition determination unit that determines whether the hydraulic system satisfies predetermined conditions for calculating volumetric efficiency of the hydraulic system; a volumetric efficiency calculation unit that calculates the volumetric efficiency when it is determined that the predetermined conditions are satisfied; a system state determination unit that determines whether the volumetric efficiency is equal to or greater than a first threshold; a pump state determination unit that determines whether a rate of change of drain pressure of the hydraulic pump is equal to or greater than a second threshold when it is determined that the volumetric efficiency is less than the first threshold; and an output unit that outputs first determination data indicating that the hydraulic pump is abnormal when it is determined that the rate of change of the drain pressure is equal to or greater than the second threshold.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a diagnostic system for a work machine and a diagnostic method for a work machine. [Background technology]

[0002] BACKGROUND ART In the technical field related to work machines, a diagnostic device for a work machine, such as that disclosed in Patent Document 1, is known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7285356 Summary of the Invention [Problem to be solved by the invention]

[0004] The hydraulic system of a work machine is composed of multiple hydraulic devices. For example, if a hydraulic device malfunctions due to aging, the operating performance of the work machine will decrease. In order to restore the operating performance of the work machine, it is necessary to identify the malfunctioning hydraulic device and perform maintenance.

[0005] The present disclosure aims to identify abnormal hydraulic equipment. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a diagnostic system for a work machine equipped with a hydraulic system having a hydraulic pump, a work implement cylinder, and a control valve that controls the flow rate and direction of hydraulic oil supplied from the hydraulic pump to the work implement cylinder, the diagnostic system comprising: a condition determination unit that determines whether the hydraulic system satisfies predetermined conditions for calculating the volumetric efficiency of the hydraulic system; a volumetric efficiency calculation unit that calculates the volumetric efficiency when it is determined that the predetermined conditions are satisfied; a system state determination unit that determines whether the volumetric efficiency is equal to or greater than a first threshold; a pump state determination unit that determines whether the rate of change of the drain pressure of the hydraulic pump is equal to or greater than a second threshold when it is determined that the volumetric efficiency is less than the first threshold; and an output unit that outputs first determination data that indicates that the hydraulic pump is abnormal when it is determined that the rate of change of the drain pressure is equal to or greater than the second threshold. [Effects of the Invention]

[0007] According to the present disclosure, abnormal hydraulic equipment is identified. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram that schematically shows a management system for a work machine according to an embodiment. [Figure 2] FIG. 2 is a diagram that schematically shows a hydraulic system of a work machine according to an embodiment. [Figure 3] FIG. 3 is a hardware configuration diagram showing the controller of the work machine according to the embodiment. [Figure 4] FIG. 4 is a functional block diagram showing a diagnostic system for a work machine according to an embodiment. [Figure 5] FIG. 5 is a flowchart showing a diagnostic method for a work machine according to the embodiment. [Figure 6] FIG. 6 is a diagram showing the relationship between the volumetric efficiency, the drain pressure, and the time elapsed since the start of the diagnosis of the hydraulic system according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0010] [Management system] FIG. 1 is a diagram schematically showing a management system 1 for a work machine 2 according to an embodiment. The management system 1 manages a work machine 2 operating at a work site 101. In the embodiment, the work machine 2 is a hydraulic excavator. The management system 1 has a management server 3. The management server 3 includes a computer system. The management server 3 is located outside the work machine 2. The management server 3 is located in a management room 102 that is located in a remote location from the work site 101. The management server 3 manages the work machine 2. The work machine 2 has a controller 50. The management server 3 can communicate with the controller 50 of the work machine 2 via a communication system 4. The management server 3 collects operation data of the work machine 2.

[0011] The communication system 4 includes a mobile phone communication network. The communication system 4 may also include a satellite communication network. The communication system 4 may also include a public communication line or a specific communication line. The communication system 4 may also include the Internet or a local area network.

[0012] [Work machinery] The work machine 2 has a running body 5, a rotating body 6 supported by the running body 5, a work implement 7 supported by the rotating body 6, and a work implement cylinder 10 that operates the work implement 7.

[0013] The running body 5 runs on the work site 101 while supporting the rotating body 6. The running body 5 has a pair of tracks 5A. The work machine 2 runs as the tracks 5A rotate. The rotating body 6 is capable of rotating while being supported by the running body 5.

[0014] The rotating unit 6 is the body of the work machine 2. The rotating unit 6 is disposed higher than the running unit 5. The rotating unit 6 is supported by the running unit 5 so as to be able to rotate. The rotating unit 6 has a cab. The operator of the work machine 2 sits in the cab.

[0015] The work implement 7 is supported by the revolving unit 6. The work implement 7 includes a boom 7A, an arm 7B, and a bucket 7C. The boom 7A is rotatably connected to the front of the revolving unit 6. The arm 7B is rotatably connected to the tip of the boom 7A. The bucket 7C is rotatably connected to the tip of the arm 7B.

[0016] The work implement cylinder 10 includes a boom cylinder 11, an arm cylinder 12, and a bucket cylinder 13. The boom cylinder 11, the arm cylinder 12, and the bucket cylinder 13 are each a hydraulic cylinder driven by hydraulic oil.

[0017] The boom cylinder 11 operates the boom 7A. The operation of the boom 7A includes a raising operation and a lowering operation. When the boom cylinder 11 extends, the boom 7A performs a raising operation. When the boom cylinder 11 retracts, the boom 7A performs a lowering operation.

[0018] The arm cylinder 12 operates the arm 7B. The operations of the arm 7B include an excavation operation and a dumping operation. When the arm cylinder 12 extends, the arm 7B performs an excavation operation. When the arm cylinder 12 retracts, the arm 7B performs a dumping operation.

[0019] The bucket cylinder 13 operates the bucket 7C. The operations of the bucket 7C include an excavation operation and a dumping operation. When the bucket cylinder 13 extends, the bucket 7C performs an excavation operation. When the bucket cylinder 13 retracts, the bucket 7C performs a dumping operation.

[0020] [Hydraulic system] 2 is a diagram schematically showing a hydraulic system 30 of a work machine 2 according to an embodiment. The work machine 2 is equipped with the hydraulic system 30. The hydraulic system 30 has an engine 31, a hydraulic pump 32, a supply passage 33, a suction passage 34, a tank 35, a bottom passage 36, a rod passage 37, a tank passage 38, a drain passage 39, a work implement cylinder 10, a control valve 40, an operation lever 27, and a controller 50. The engine 31, the hydraulic pump 32, and the tank 35 are each disposed in a machine room of the revolving body 6.

[0021] The engine 31 is a power source for the work machine 2. An example of the engine 31 is a diesel engine.

[0022] The hydraulic pump 32 is driven by power transmitted from the engine 31. The hydraulic pump 32 discharges hydraulic oil. The hydraulic pump 32 is a variable displacement hydraulic pump. The supply passage 33 is connected to the discharge port of the hydraulic pump 32. The suction passage 34 is connected to the suction port of the hydraulic pump 32. The hydraulic pump 32 sucks hydraulic oil stored in a tank 35 via the suction passage 34. The hydraulic pump 32 discharges the hydraulic oil sucked via the suction passage 34 to the supply passage 33.

[0023] The drain passage 39 connects the hydraulic pump 32 and the tank 35. When the hydraulic pump 32 is driven, there is a possibility that hydraulic oil may leak from the sliding parts of the hydraulic pump 32. The hydraulic oil that leaks from the sliding parts of the hydraulic pump 32 is discharged into the tank 35 via the drain passage 39.

[0024] The work implement cylinder 10 operates the work implement 7 based on hydraulic oil supplied from the hydraulic pump 32. As described above, the work implement cylinder 10 includes the boom cylinder 11 that operates the boom 7A, the arm cylinder 12 that operates the arm 7B, and the bucket cylinder 13 that operates the bucket 7C.

[0025] The work machine cylinder 10 has a bottom chamber 10A and a rod chamber 10B. When hydraulic oil is supplied to the bottom chamber 10A, the work machine cylinder 10 extends. When hydraulic oil is supplied to the rod chamber 10B, the work machine cylinder 10 retracts.

[0026] The supply flow path 33 is connected to the discharge port of the hydraulic pump 32. The hydraulic oil discharged from the discharge port of the hydraulic pump 32 flows through the supply flow path 33. The hydraulic oil discharged from the hydraulic pump 32 and flowing through the supply flow path 33 is supplied to the work implement cylinder 10.

[0027] The control valve 40 controls the flow rate and direction of hydraulic oil supplied from the hydraulic pump 32 to the work implement cylinder 10. The bottom chamber 10A of the work implement cylinder 10 is connected to the control valve 40 via a bottom flow path 36. The rod chamber 10B of the work implement cylinder 10 is connected to the control valve 40 via a rod flow path 37.

[0028] The control valve 40 includes a boom control valve 41 that controls the flow rate and direction of hydraulic oil supplied to the boom cylinder 11, an arm control valve 42 that controls the flow rate and direction of hydraulic oil supplied to the arm cylinder 12, and a bucket control valve 43 that controls the flow rate and direction of hydraulic oil supplied to the bucket cylinder 13. The hydraulic oil discharged from the hydraulic pump 32 to the supply flow path 33 is supplied to each of the boom control valve 41, the arm control valve 42, and the bucket control valve 43.

[0029] The hydraulic pump 32 can supply hydraulic oil to each of the boom control valve 41, the arm control valve 42, and the bucket control valve 43 via the supply passage 33. A branch supply passage 33A is connected to each of the boom control valve 41, the arm control valve 42, and the bucket control valve 43. The supply passage 33 is connected to each of the three branch supply passages 33A. The hydraulic oil discharged from the hydraulic pump 32 to the supply passage 33 is supplied to each of the boom control valve 41, the arm control valve 42, and the bucket control valve 43 via the branch supply passage 33A.

[0030] The control valve 40 has a pump port Ta, a bottom port Tb, a rod port Tc, and a tank port Td.

[0031] The pump port Ta is connected to the hydraulic pump 32 via the branch supply flow path 33A and the supply flow path 33. The hydraulic oil discharged from the hydraulic pump 32 can flow into the control valve 40 from the pump port Ta after circulating through the supply flow path 33 and the branch supply flow path 33A.

[0032] The bottom port Tb is connected to the bottom chamber 10A of the work implement cylinder 10 via a bottom flow path 36. The hydraulic oil that flows out from the bottom port Tb can flow through the bottom flow path 36 and then into the bottom chamber 10A of the work implement cylinder 10. In addition, the hydraulic oil that flows out from the bottom chamber 10A of the work implement cylinder 10 can flow through the bottom flow path 36 and then into the control valve 40 from the bottom port Tb.

[0033] The rod port Tc is connected to the rod chamber 10B of the work implement cylinder 10 via the rod flow path 37. The hydraulic oil flowing out from the rod port Tc can flow through the rod flow path 37 and then into the rod chamber 10B of the work implement cylinder 10. In addition, the hydraulic oil flowing out from the rod chamber 10B of the work implement cylinder 10 can flow into the control valve 40 from the rod port Tc after flowing through the rod flow path 37.

[0034] The tank port Td is connected to the tank 35 via a tank flow path 38. The hydraulic oil flowing out from the tank port Td flows through the tank flow path 38 and then is discharged into the tank 35.

[0035] The control valve 40 is a slide spool type flow control valve that moves a rod-shaped spool to switch the flow rate and direction of hydraulic oil supplied to the work equipment cylinder 10. Axial movement of the spool switches between supplying hydraulic oil to the bottom chamber 10A and supplying hydraulic oil to the rod chamber 10B. The flow rate of hydraulic oil supplied to the work equipment cylinder 10 is adjusted based on the amount of movement of the spool.

[0036] In the embodiment, the spool of the control valve 40 moves to a bottom position T1 that supplies hydraulic oil to the bottom chamber 10A of the work equipment cylinder 10, a rod position T2 that supplies hydraulic oil to the rod chamber 10B of the work equipment cylinder 10, and a neutral position T3 that is located between the bottom position T1 and the rod position T2 and does not allow hydraulic oil to flow.

[0037] When the spool of the control valve 40 is positioned at the bottom position T1, hydraulic oil discharged from the hydraulic pump 32 flows through the supply passage 33 and the branch supply passage 33A, then flows into the control valve 40 from the pump port Ta, and flows out from the bottom port Tb. The hydraulic oil that flows out from the bottom port Tb flows through the bottom passage 36, then flows into the bottom chamber 10A of the work implement cylinder 10. This causes the work implement cylinder 10 to extend. When the work implement cylinder 10 extends, hydraulic oil flows out from the rod chamber 10B. The hydraulic oil that flows out from the rod chamber 10B of the work implement cylinder 10 flows through the rod passage 37, then flows into the control valve 40 from the rod port Tc, and flows out from the tank port Td. The hydraulic oil that flows out from the tank port Td is discharged into the tank 35 via the tank passage 38.

[0038] When the spool of the control valve 40 is positioned at the rod position T2, hydraulic oil discharged from the hydraulic pump 32 flows through the supply passage 33 and the branch supply passage 33A, then flows into the control valve 40 from the pump port Ta, and flows out from the rod port Tc. The hydraulic oil that flows out from the rod port Tc flows through the rod passage 37, then flows into the rod chamber 10B of the work implement cylinder 10. This causes the work implement cylinder 10 to retract. When the work implement cylinder 10 retracts, hydraulic oil flows out from the bottom chamber 10A. The hydraulic oil that flows out from the bottom chamber 10A of the work implement cylinder 10 flows through the bottom passage 36, then flows into the control valve 40 from the bottom port Tb, and flows out from the tank port Td. The hydraulic oil that flows out from the tank port Td is discharged into the tank 35 via the tank passage 38.

[0039] When the spool of the control valve 40 is located in the neutral position T3, hydraulic oil cannot flow through the control valve 40.

[0040] The work lever 27 is disposed in the cab of the revolving body 6. The work lever 27 is operated by an operator of the work machine 2. The work lever 27 is operated by the operator so as to drive the work implement cylinder 10. When the work lever 27 is operated, operation data is generated in the work lever 27. The operation data generated in the work lever 27 is transmitted to the controller 50. The controller 50 outputs a control command for moving the spool of the control valve 40 based on the operation data from the work lever 27. When the spool of the control valve 40 moves, the work implement cylinder 10 extends and retracts, and the work implement 7 operates.

[0041] The working levers 27 include a left working lever 27L and a right working lever 27R. When the working lever 27 is in the neutral state, the spool of the control valve 40 is disposed in the neutral position T3. When the left working lever 27L is in the neutral state, the spool of the arm control valve 42 is disposed in the neutral position T3. When the right working lever 27R is in the neutral state, the spool of the boom control valve 41 and the spool of the bucket control valve 43 are each disposed in the neutral position T3.

[0042] The hydraulic system 30 also includes a stroke sensor 21, a swash plate angle sensor 22, an engine speed sensor 23, a drain pressure sensor 24, a pump pressure sensor 25, and a hydraulic oil temperature sensor 26.

[0043] The stroke sensor 21 detects the stroke length of the work implement cylinder 10. The stroke sensor 21 detects the stroke lengths of the boom cylinder 11, the arm cylinder 12, and the bucket cylinder 13. The detection data of the stroke sensor 21 is transmitted to the controller 50. The controller 50 can calculate the speed of the work implement cylinder 10 based on the stroke length of the work implement cylinder 10.

[0044] The swash plate angle sensor 22 detects the angle of the swash plate of the hydraulic pump 32. The hydraulic pump 32 is a variable displacement hydraulic pump that has a swash plate for changing the pump displacement. The detection data of the swash plate angle sensor 22 is transmitted to the controller 50. The controller 50 can calculate the pump displacement of the hydraulic pump 32 based on the angle of the swash plate.

[0045] The engine speed sensor 23 detects the number of revolutions per unit time of the engine 31. The detected data of the engine speed sensor 23 is transmitted to the controller 50.

[0046] The drain pressure sensor 24 detects drain pressure, which indicates the pressure of hydraulic oil leaking from the sliding parts of the hydraulic pump 32. The drain pressure sensor 24 is arranged in the drain flow path 39. The hydraulic oil leaking from the sliding parts of the hydraulic pump 32 flows through the drain flow path 39. The drain pressure is detected by detecting the pressure of the hydraulic oil flowing through the drain flow path 39. The greater the amount of hydraulic oil leaking from the sliding parts of the hydraulic pump 32, the higher the drain pressure. The detection data of the drain pressure sensor 24 is sent to the controller 50.

[0047] The pump pressure sensor 25 detects the pump pressure, which indicates the pressure of the hydraulic oil discharged from the discharge port of the hydraulic pump 32. The pump pressure sensor 25 is disposed in the supply flow path 33. The detection data of the pump pressure sensor 25 is transmitted to the controller 50.

[0048] The hydraulic oil temperature sensor 26 detects the temperature of the hydraulic oil flowing through the hydraulic system 30. The hydraulic oil temperature sensor 26 is disposed in the intake passage 34. The detection data of the hydraulic oil temperature sensor 26 is transmitted to the controller 50.

[0049] [controller] FIG. 3 is a hardware configuration diagram showing a controller 50 of a work machine 2 according to an embodiment. The controller 50 includes a computer system. The controller 50 has a processor 51 such as a CPU (Central Processing Unit), a main memory 52 including non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory), a storage 53, and an interface 54 including an input / output circuit. The functions of the controller 50 are stored in the storage 53 as a computer program. The processor 51 reads the computer program from the storage 53 and loads it into the main memory 52, and executes processing in accordance with the computer program. The computer program may be distributed to the controller 50 via a network.

[0050] The management server 3 also includes a computer system. The management server 3 has a processor, a main memory, a storage, and an interface.

[0051] [Diagnostic System] FIG. 4 is a functional block diagram showing a diagnostic system 60 of a work machine 2 according to an embodiment. The management system 1 includes the diagnostic system 60. The diagnostic system 60 diagnoses the hydraulic system 30 of the work machine 2. The hydraulic system 30 is made up of a plurality of hydraulic devices including a hydraulic pump 32 and a control valve 40. For example, an abnormality may occur in the hydraulic devices due to aging deterioration. The diagnostic system 60 identifies the abnormal hydraulic device. In an embodiment, the diagnostic system 60 determines whether the hydraulic pump 32 is abnormal. The diagnostic system 60 determines whether the control valve 40 is abnormal. In an embodiment, the diagnostic system 60 diagnoses the hydraulic system 30 based on the volumetric efficiency η of the hydraulic system 30.

[0052] The diagnostic system 60 diagnoses the hydraulic system 30 while the work machine 2 is operating at the work site 101. The diagnostic system 60 diagnoses the hydraulic system 30 in parallel with the operation of the work machine 2. The diagnostic system 60 includes a management server 3, a controller 50, a stroke sensor 21, a swash plate angle sensor 22, an engine rotation speed sensor 23, a drain pressure sensor 24, a pump pressure sensor 25, a hydraulic oil temperature sensor 26, and an operating lever 27.

[0053] The controller 50 includes a data input unit 61, a condition determination unit 62, and a volumetric efficiency calculation unit 63. The management server 3 includes a system state determination unit 64, a pump state determination unit 65, and an output unit 66.

[0054] An output device 55 is connected to the management server 3. Examples of the output device 55 include a display device that outputs display data and an audio output device that outputs audio data. Examples of the display device include a flat panel display such as a liquid crystal display or an organic EL display.

[0055] The data input unit 61 acquires detection data from the stroke sensor 21, the swash plate angle sensor 22, the engine speed sensor 23, the drain pressure sensor 24, the pump pressure sensor 25, the hydraulic oil temperature sensor 26, and operation data from the operating lever 27.

[0056] The condition determination unit 62 determines whether the hydraulic system 30 satisfies predetermined conditions for calculating the volumetric efficiency η of the hydraulic system 30. As described above, a plurality of work implement cylinders 10 are provided. A plurality of control valves 40 are provided corresponding to the work implement cylinders 10. The control valves 40 include a boom control valve 41 corresponding to the boom cylinder 11, an arm control valve 42 corresponding to the arm cylinder 12, and a bucket control valve 43 corresponding to the bucket cylinder 13. The predetermined conditions include one of the plurality of work implement cylinders 10 being driven while the traveling unit 5 and the rotating unit 6 are stopped. In other words, the predetermined conditions include two of the three work implement cylinders 10 being stopped and one work implement cylinder 10 being extended or retracted while the traveling unit 5 and the rotating unit 6 are stopped. In other words, the predetermined conditions include the spools of two of the three control valves 40 being positioned at the neutral position T3 and the spool of one control valve 40 being positioned at the bottom position T1 or the rod position T2. ​​The predetermined conditions include the two of the three work implement elements (boom 7A, arm 7B, bucket 7C) of the work implement 7 not operating and one work implement element operating.

[0057] In the embodiment, the condition determination unit 62 determines whether or not a predetermined condition is satisfied based on the operation data (operation signal) of the work lever 27. For example, when the work lever 27 is operated so that the spool of the boom control valve 41 and the spool of the arm control valve 42 are positioned in the neutral position T3 and the spool of the bucket control valve 43 is positioned in the bottom position T1 or the rod position T2, the condition determination unit 62 determines that the predetermined condition is satisfied based on the operation data of the work lever 27. When the work lever 27 is operated so that the spool of the arm control valve 42 and the spool of the bucket control valve 43 are positioned in the neutral position T3 and the spool of the boom control valve 41 is positioned in the bottom position T1 or the rod position T2, the condition determination unit 62 determines that the predetermined condition is satisfied based on the operation data of the work lever 27. When the working lever 27 is operated so that the spool of the bucket control valve 43 and the spool of the boom control valve 41 are positioned in the neutral position T3 and the spool of the arm control valve 42 is positioned in the bottom position T1 or the rod position T2, the condition determination unit 62 determines that the specified condition is satisfied based on the operation data of the working lever 27.

[0058] The condition determination unit 62 may determine whether or not one of the plurality of work machine cylinders 10 is being driven, based on detection data from the stroke sensor 21. When a spool sensor that detects the movement distance of the spool of the control valve 40 is provided, the condition determination unit 62 may determine whether or not one of the plurality of work machine cylinders 10 is being driven, based on detection data from the spool sensor. When a control command to move the spool of the control valve 40 is output from the controller 50, the condition determination unit 62 may determine whether or not one of the plurality of work machine cylinders 10 is being driven, based on the control command.

[0059] The predetermined condition may include that the pump pressure of the hydraulic pump 32 is within a specified pressure range. The condition determination unit 62 can determine whether the predetermined condition is satisfied based on the detection data of the pump pressure sensor 25. The amount of leakage from the sliding parts of the hydraulic pump 32 varies depending on the pump pressure. If the pump pressure is too high or too low, it may be difficult to accurately calculate the volumetric efficiency η. By calculating the volumetric efficiency η when the pump pressure is within a specified pressure range, the volumetric efficiency η can be calculated with high accuracy.

[0060] The predetermined condition may include the temperature of the hydraulic oil being within a specified temperature range. The condition determination unit 62 can determine whether the predetermined condition is satisfied based on the detection data of the hydraulic oil temperature sensor 26. The viscosity of the hydraulic oil changes depending on the temperature of the hydraulic oil. If the temperature of the hydraulic oil is too high or too low, it may be difficult to accurately calculate the volumetric efficiency η. By calculating the volumetric efficiency η when the temperature of the hydraulic oil is within a specified temperature range, the volumetric efficiency η can be calculated accurately.

[0061] The predetermined condition may include the discharge flow rate of the hydraulic pump 32 being within a predetermined flow rate range. The condition determination unit 62 can determine whether the predetermined condition is satisfied based on flow rate data calculated from the detection data of the swash plate angle sensor 22 and the detection data of the engine speed sensor 23. The volumetric efficiency varies depending on the pump discharge flow rate, even if the leakage amount from the sliding parts of the hydraulic pump 32 is the same. If the pump discharge flow rate is too high or too low, it may be difficult to accurately calculate the volumetric efficiency η. By calculating the volumetric efficiency η when the pump discharge flow rate is within a predetermined flow rate range, the volumetric efficiency η can be calculated accurately.

[0062] If it is determined that the predetermined conditions are satisfied, the volumetric efficiency calculation unit 63 calculates the volumetric efficiency η of the hydraulic system 30. If the flow rate of the hydraulic oil discharged from the hydraulic pump 32 is Qt [L / min] and the flow rate of the hydraulic oil flowing into the work equipment cylinder 10 is Qp [L / min], the volumetric efficiency η [%] of the hydraulic system 30 is expressed by the following equation (1).

[0063]

number

[0064] When the spool of the boom control valve 41 and the spool of the arm control valve 42 are positioned in the neutral position T3 and the spool of the bucket control valve 43 is positioned in the bottom position T1 or the rod position T2, the flow rate Qp is the flow rate of hydraulic oil flowing into the bucket cylinder 13 via the bucket control valve 43. When the spool of the arm control valve 42 and the spool of the bucket control valve 43 are positioned in the neutral position T3 and the spool of the boom control valve 41 is positioned in the bottom position T1 or the rod position T2, the flow rate Qp is the flow rate of hydraulic oil flowing into the boom cylinder 11 via the boom control valve 41. When the spool of the bucket control valve 43 and the spool of the boom control valve 41 are positioned in the neutral position T3 and the spool of the arm control valve 42 is positioned in the bottom position T1 or the rod position T2, the flow rate Qp is the flow rate of hydraulic oil flowing into the arm cylinder 12 via the arm control valve 42.

[0065] Pump volume Cq [cm 3 / rev] and the engine speed is Ne [rpm], the flow rate Qt [L / min] is expressed by the following equation (2). The volumetric efficiency calculation unit 63 can calculate the pump amount Cq based on the detection data of the swash plate angle sensor 22. The volumetric efficiency calculation unit 63 can calculate the engine speed Ne based on the detection data of the engine speed sensor 23.

[0066]

number

[0067] The pressure-receiving area of ​​the work machine cylinder 10 is As [mm 2] and the cylinder speed is Vs [mm / s], the flow rate Qp [L / min] is expressed by the following equation (3). The pressure-receiving area As is known data that can be determined from the specification data of the work equipment cylinder 10. The volumetric efficiency calculation unit 63 can calculate the cylinder speed Vs based on the detection data of the stroke sensor 21. The cylinder speed Vs refers to the moving speed of the rod of the work equipment cylinder 10.

[0068]

number

[0069] The system state determination unit 64 determines whether the volumetric efficiency η calculated by the volumetric efficiency calculation unit 63 is equal to or greater than a predetermined first threshold value. If the volumetric efficiency η is less than the first threshold value, the system state determination unit 64 determines that at least one of the hydraulic pump 32 and the control valve 40 of the hydraulic system 30 is abnormal.

[0070] When the system state determination unit 64 determines that the volumetric efficiency η is less than the first threshold, the pump state determination unit 65 determines whether the rate of change in the drain pressure of the hydraulic pump 32 is equal to or greater than a predetermined second threshold. The pump state determination unit 65 can determine whether the rate of change in the drain pressure is equal to or greater than the second threshold based on the detection data of the drain pressure sensor 24. The rate of change in the drain pressure refers to the amount of increase in the drain pressure per unit time. An increase in the drain pressure means that a large amount of hydraulic oil has leaked from the sliding parts of the hydraulic pump 32. When the rate of change in the drain pressure is equal to or greater than the second threshold, that is, when the drain pressure of the hydraulic pump 32 increases rapidly, the pump state determination unit 65 determines that the hydraulic pump 32 is abnormal.

[0071] If the rate of change of the drain pressure is less than the second threshold value, i.e., if the rate of change of the drain pressure of the hydraulic pump 32 is small, the pump state determination unit 65 determines that the hydraulic pump 32 is normal and that the control valve 40 is abnormal. Abnormalities in the control valve 40 include a state in which hydraulic oil is leaking from a sliding part of the control valve 40.

[0072] When the spool of the boom control valve 41 and the spool of the arm control valve 42 are positioned in the neutral position T3 and the spool of the bucket control valve 43 is positioned in the bottom position T1 or the rod position T2, and when the rate of change of the drain pressure is determined to be less than the second threshold value, the pump state determination unit 65 determines that the bucket control valve 43 is abnormal. When the spool of the arm control valve 42 and the spool of the bucket control valve 43 are positioned in the neutral position T3 and the spool of the boom control valve 41 is positioned in the bottom position T1 or the rod position T2, and when the rate of change of the drain pressure is determined to be less than the second threshold value, the pump state determination unit 65 determines that the boom control valve 41 is abnormal. When the spool of the bucket control valve 43 and the spool of the boom control valve 41 are positioned in the neutral position T3 and the spool of the arm control valve 42 is positioned in the bottom position T1 or the rod position T2, and when the rate of change of the drain pressure is determined to be less than the second threshold value, the pump state determination unit 65 determines that the arm control valve 42 is abnormal.

[0073] When it is determined that the rate of change of the drain pressure is equal to or greater than the second threshold, the output unit 66 outputs first determination data indicating that the hydraulic pump 32 is abnormal. When it is determined that the rate of change of the drain pressure is less than the second threshold, the output unit 66 outputs second determination data indicating that the control valve 40 is abnormal. The output unit 66 outputs a control command to the output device 55 so that at least one of the first determination data and the second determination data is output from the output device 55.

[0074] [Diagnostic method] 5 is a flowchart showing a method for diagnosing a work machine 2 according to the embodiment. The data input unit 61 acquires detection data from the stroke sensor 21, detection data from the swash plate angle sensor 22, detection data from the engine speed sensor 23, detection data from the drain pressure sensor 24, detection data from the pump pressure sensor 25, detection data from the hydraulic oil temperature sensor 26, and operation data from the work lever 27 (step S1).

[0075] The condition determination unit 62 determines whether the hydraulic system 30 satisfies predetermined conditions for calculating the volumetric efficiency of the hydraulic system 30. The condition determination unit 62 determines whether a predetermined condition that one of the plurality of work implement cylinders 10 is driven is satisfied based on the operation data of the work lever 27 (step S2). Note that in step S2, the predetermined conditions may include the pump pressure of the hydraulic pump 32 being within a specified pressure range, the temperature of the hydraulic oil being within a specified temperature range, and the flow rate of the hydraulic oil being within a specified flow rate range.

[0076] If it is determined in step S2 that the predetermined condition is not satisfied (step S2: No), the process returns to step S1. If it is determined in step S2 that the predetermined condition is satisfied (step S2: Yes), the volumetric efficiency calculation unit 63 calculates the volumetric efficiency η of the hydraulic system 30 based on the above-mentioned equations (1), (2), and (3) (step S3).

[0077] The volumetric efficiency calculation unit 63 transmits the volumetric efficiency η calculated in step S3 to the management server 3 via the communication system 4. The data input unit 61 transmits the detection data of the drain pressure sensor 24 to the management server 3 via the communication system 4 (step S4).

[0078] The system state determination unit 64 determines whether the volumetric efficiency η calculated by the volumetric efficiency calculation unit 63 is equal to or greater than a predetermined first threshold value (step S5).

[0079] In step S5, if it is determined that the volumetric efficiency η is equal to or greater than the first threshold value (step S5: Yes), the process returns to step S1.

[0080] 6 is a diagram showing the relationship between the volumetric efficiency η, the drain pressure Pd, and the time t that has elapsed since the start of the diagnosis of the hydraulic system 30 according to this embodiment. As shown in Fig. 6, when it is determined in step S5 that the volumetric efficiency η is less than the first threshold value (step S5: No), the pump state determination unit 65 determines whether the rate of change of the drain pressure of the hydraulic pump 32 is equal to or greater than a predetermined second threshold value (step S6).

[0081] 6, when the rate of change of the drain pressure is equal to or greater than the second threshold, the pump state determination unit 65 determines that the control valve 40 is normal and that the hydraulic pump 32 is abnormal. When the rate of change of the drain pressure is less than the second threshold, the pump state determination unit 65 determines that the hydraulic pump 32 is normal and that the control valve 40 is abnormal.

[0082] In step S6, if it is determined that the rate of change of the drain pressure is greater than or equal to the second threshold value (step S6: Yes), the output unit 66 outputs first determination data indicating that the control valve 40 is normal and that the hydraulic pump 32 is abnormal (step S7).

[0083] In step S6, if it is determined that the rate of change of the drain pressure is less than the second threshold value (step S6: No), the output unit 66 outputs second determination data indicating that the hydraulic pump 32 is normal and the control valve 40 is abnormal (step S8).

[0084] At least one of the first judgment data and the second judgment data is output from the output device 55. At least one of the first judgment data and the second judgment data may be transmitted to the controller 50 via the communication system 4. If a monitor is mounted in the cab of the work machine 2, at least one of the first judgment data and the second judgment data may be output from the monitor.

[0085] The first determination data may include recommendation data that recommends maintenance of the hydraulic pump 32. The second determination data may include recommendation data that recommends maintenance of the control valve .

[0086] [effect] As described above, the diagnostic system 60 of the work machine 2 according to the embodiment includes a condition determination unit 62 that determines whether the hydraulic system 30 satisfies predetermined conditions for calculating the volumetric efficiency η of the hydraulic system 30, a volumetric efficiency calculation unit 63 that calculates the volumetric efficiency η when it is determined that the predetermined conditions are satisfied, a system state determination unit 64 that determines whether the volumetric efficiency η is equal to or greater than a first threshold value, a pump state determination unit 65 that determines whether the rate of change of the drain pressure Pd of the hydraulic pump 32 is equal to or greater than a second threshold value when it is determined that the volumetric efficiency η is less than the first threshold value, and an output unit 66 that outputs first determination data indicating that the hydraulic pump 32 is abnormal when it is determined that the rate of change of the drain pressure Pd is equal to or greater than the second threshold value.

[0087] According to the embodiment, the volumetric efficiency η of the hydraulic system 30 is calculated for the hydraulic system 30 having the hydraulic pump 32 and the control valve 40. The volumetric efficiency η correlates with the amount of hydraulic oil leaking from the sliding parts of the hydraulic system 30. When the volumetric efficiency η is small (less than a first threshold value), the system state determination unit 64 determines that the amount of hydraulic oil leaking from the sliding parts of the hydraulic system 30 is large. That is, when the volumetric efficiency η is less than the first threshold value, the system state determination unit 64 determines that hydraulic oil is leaking from the sliding parts of one of the hydraulic pump 32 and the control valve 40. When the rate of change of the drain pressure Pd is large (equal to or greater than a second threshold value), the pump state determination unit 65 determines that hydraulic oil is leaking from the sliding parts of the hydraulic pump 32. Because abnormal hydraulic equipment leaking hydraulic oil from the sliding parts is identified, the hydraulic equipment is properly maintained. Because the hydraulic equipment is maintained, deterioration in the operating performance of the work machine 2 is suppressed. Furthermore, the diagnostic system 60 can efficiently identify abnormal hydraulic equipment without causing the work machine 2 to stop operating.

[0088] [Another embodiment] In the above-described embodiment, an angle sensor such as a potentiometer may be provided instead of the stroke sensor 21. The condition determination unit 62 may determine whether one of the plurality of work machine cylinders 10 is being driven based on the detection data of the angle sensor. The volumetric efficiency calculation unit 63 may calculate the cylinder speed Vs based on the detection data of the angle sensor.

[0089] In the above-described embodiment, the hydraulic system 30 has three control valves 40. The hydraulic system 30 may have one control valve 40. Even when the hydraulic system 30 has one hydraulic pump 32 and one control valve 40, the diagnostic system 60 can identify that the abnormal hydraulic device is either the hydraulic pump 32 or the control valve 40 according to the above-described embodiment. When the hydraulic system 30 has one hydraulic pump 32 and one control valve 40, the predetermined condition for calculating the volumetric efficiency of the hydraulic system 30 may be simply that the pump pressure of the hydraulic pump 32 is within a specified pressure range, or that the temperature of the hydraulic oil is within a specified temperature range, or that the flow rate of the hydraulic oil is within a specified flow rate range.

[0090] In the above-described embodiment, at least some of the functions of the controller 50 may be provided in the management server 3, or at least some of the functions of the management server 3 may be provided in the controller 50. For example, the data input unit 61, the condition determination unit 62, the volumetric efficiency calculation unit 63, the system state determination unit 64, the pump state determination unit 65, and the output unit 66 may each be provided in the controller 50.

[0091] In the above-described embodiment, the data input unit 61, the condition determination unit 62, the volumetric efficiency calculation unit 63, the system state determination unit 64, the pump state determination unit 65, and the output unit 66 may each be configured as separate hardware (computer systems). [Explanation of symbols]

[0092] 1...management system, 2...work machine, 3...management server, 4...communication system, 5...traveling body, 5A...track, 6...swivel body, 7...work implement, 7A...boom, 7B...arm, 7C...bucket, 10...work implement cylinder, 10A...bottom chamber, 10B...rod chamber, 11...boom cylinder, 12...arm cylinder, 13...bucket cylinder, 21...stroke sensor, 22...swash plate angle sensor, 23...engine rotation speed sensor, 24...drain pressure sensor, 25...pump pressure sensor, 26...hydraulic oil temperature sensor, 27...work lever, 27L...left work lever, 27R...right work lever, 30...hydraulic system, 31...engine, 32...hydraulic pump, 33...supply flow path, 33A...branched supply flow path, 34...suction flow path , 35...tank, 36...bottom flow path, 37...rod flow path, 38...tank flow path, 39...drain flow path, 40...control valve, 41...boom control valve, 42...arm control valve, 43...bucket control valve, 50...controller, 51...processor, 52...main memory, 53...storage, 54...interface, 55...output device, 60...diagnostic system, 61...data input section, 62...condition judgment section, 63...volumetric efficiency calculation section, 64...system status judgment section, 65...pump status judgment section, 66...output section, 101...work site, 102...control room, Ta...pump port, Tb...bottom port, Tc...rod port, Td...tank port, T1...bottom position, T2...rod position, T3...neutral position.

Claims

1. A diagnostic system for a work machine including a hydraulic system having a hydraulic pump, a work implement cylinder, and a control valve that controls the flow rate and direction of hydraulic oil supplied from the hydraulic pump to the work implement cylinder, a condition determination unit that determines whether the hydraulic system satisfies a predetermined condition for calculating the volumetric efficiency of the hydraulic system; a volumetric efficiency calculation unit that calculates the volumetric efficiency when it is determined that the predetermined condition is satisfied; and a system state determination unit that determines whether the volumetric efficiency is equal to or greater than a first threshold value; a pump state determination unit that, when it is determined that the volumetric efficiency is less than a first threshold value, determines whether a rate of change in drain pressure of the hydraulic pump is equal to or greater than a second threshold value; an output unit that outputs first determination data indicating that the hydraulic pump is abnormal when it is determined that the rate of change of the drain pressure is equal to or greater than a second threshold value, Diagnostic systems for work machines.

2. The output unit outputs second determination data indicating that the control valve is abnormal when it is determined that the rate of change of the drain pressure is less than a second threshold value. The diagnostic system for a work machine according to claim 1 .

3. The work machine cylinder is provided in plurality, A plurality of the control valves are provided corresponding to the work machine cylinders, the predetermined condition includes that one of the plurality of work machine cylinders is driven. The diagnostic system for a work machine according to claim 1 .

4. The hydraulic system has an operation lever that is operated to drive the work machine cylinder, The condition determination unit determines whether the predetermined condition is satisfied based on the operation data of the working lever. The diagnostic system for a work machine according to claim 3.

5. The predetermined condition includes that the pump pressure of the hydraulic pump is within a specified pressure range. The diagnostic system for a work machine according to claim 3.

6. The predetermined condition includes that the temperature of the hydraulic oil is within a specified temperature range. The diagnostic system for a work machine according to claim 3.

7. The predetermined condition includes that the flow rate of the hydraulic oil is within a specified flow rate range. The diagnostic system for a work machine according to claim 3.

8. A diagnostic method for a work machine equipped with a hydraulic system having a hydraulic pump, a work implement cylinder, and a control valve that controls the flow rate and direction of hydraulic oil supplied from the hydraulic pump to the work implement cylinder, comprising: determining whether the hydraulic system satisfies predetermined conditions for calculating a volumetric efficiency of the hydraulic system; calculating the volumetric efficiency when it is determined that the predetermined condition is satisfied; determining whether the volumetric efficiency is equal to or greater than a first threshold value; When it is determined that the volumetric efficiency is less than a first threshold value, determining whether a rate of change of a drain pressure of the hydraulic pump is equal to or greater than a second threshold value; outputting first determination data indicating that the hydraulic pump is abnormal when it is determined that the rate of change of the drain pressure is equal to or greater than a second threshold value. A method for diagnosing a work machine.

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