Failure diagnosis system

Abstract

According to the present invention, a control device is caused to execute processing in which, when a diagnosis start command is input, a brake device is brought into a braking state to lock rotation of a hydraulic motor, and a signal is output for starting supply of hydraulic fluid to a first input / output port out of two input / output ports related to the hydraulic motor using a directional control valve for controlling the hydraulic fluid supplied to the hydraulic motor, and when a pressure (Pa) in the first input / output port reaches a first value (P1a), supply of the hydraulic fluid to the first input / output port is interrupted, a first time (Ta) taken from the time at which interrupting the supply of the hydraulic fluid is started, to a time at which the pressure in the first input / output port drops to a second value (P2a), is calculated, and a sign of an abnormality in the hydraulic motor and related hydraulic equipment thereof is detected on the basis of the first time.

Description

Failure Diagnosis System

[0001] The present invention relates to a failure diagnosis system for hydraulic motors widely used as a power source for hydraulic excavators, cranes, other various hydraulic machines, and hydraulic devices.

[0002] As a system for detecting an abnormality in a hydraulic rotating machine such as a hydraulic motor or a hydraulic pump, there is known a system comprising: a merging circuit that merges hydraulic oil from respective outflow ports of a plurality of hydraulic rotating machines; a flow dividing circuit that divides and supplies hydraulic oil to respective inflow ports of the plurality of hydraulic rotating machines; a plurality of temperature sensors provided at corresponding equivalent positions of the plurality of hydraulic rotating machines respectively; and a processing device that acquires temperature signals from each of the temperature sensors, performs comparison calculation, and detects wear of the plurality of hydraulic rotating machines (Patent Document 1).

[0003] Japanese Patent No. 5499334

[0004] Patent Document 1 mentions a system applicable not only to hydraulic pumps but also to hydraulic motors. However, since this technology employs a detection method that requires a plurality of hydraulic rotating machines, it cannot be applied to a system having a single hydraulic motor (hydraulic rotating machine). Furthermore, even if it were to be applied, the method of Patent Document 1, which relies on temperature that can easily fluctuate depending on operating conditions, still leaves room for improvement in the detection accuracy of abnormal signs.

[0005] An object of the present invention is to provide a failure diagnosis system capable of accurately detecting abnormal signs of a hydraulic motor even in a system including a single hydraulic motor.

[0006] The present invention includes multiple means for solving the above problems, but to give one example, in a fault diagnosis system for a hydraulic motor and related hydraulic equipment mounted on a work machine, the system includes a brake device for braking the hydraulic motor, a directional control valve having a first switching position for supplying pressurized oil to a first input / output port of the two input / output ports of the hydraulic motor, and a neutral position for shutting off the supply of pressurized oil to the two input / output ports and preventing the pressurized oil supplied to the two input / output ports from being discharged into a tank, a first pressure sensor for detecting the pressure of the pressurized oil supplied to the first input / output port, and a control device for controlling the directional control valve, wherein when a diagnosis start command is input, the control device brakes the The system outputs a brake command to the device to lock the rotation of the hydraulic motor, outputs a switching signal to the directional control valve to switch the directional control valve to the first switching position so that pressurized oil is supplied to the first input / output port, and when the first pressure sensor detects that the pressure at the first input / output port has reached a first value, it outputs a signal to the directional control valve to switch it to the neutral position to shut off the supply of pressurized oil to the first input / output port, calculates the first time elapsed from the start of the shutdown of the supply of pressurized oil until the pressure at the first input / output port drops to a second value, and detects signs of abnormality in the hydraulic motor and its related hydraulic equipment based on this first time.

[0007] According to the present invention, even in a system equipped with a single hydraulic motor, signs of abnormality in the hydraulic motor can be detected with high accuracy.

[0008] A side view of a hydraulic excavator 1, which is one of the working machines according to an embodiment of the present invention. A schematic diagram of the fault diagnosis system and related hardware according to an embodiment of the present invention. A cross-sectional view of a hydraulic motor 40. An image diagram of the leakage flow rate related to the pipelines 41A and 41B from the directional control valve 30 to the hydraulic motor 40. A functional block diagram explaining the processing performed by the processor of the controller 50, with each function being blocked into blocks. A calculation processing flow by the controller (processor) 50 according to the first embodiment. A schematic diagram of the case when abnormality diagnosis is performed on the server. A diagram showing an example of the waveforms of the pressure acting on the operating part 34A of the directional control valve 30, the pressure of the pump 20, and the pressure Pa of the first input / output port 64a of the motor 40 when the controller 50 is operated according to the flow in Figure 6. A diagram showing an example of the pressure waveform when leakage increases (when there are signs of abnormality). A calculation processing flow by the controller (processor) 50 according to the second embodiment. A diagram showing an example of a combination of leakage size and abnormality location. A diagram showing an example of a case where the combination of time Ta and Tb is classified into 25 patterns, and the degree of risk in the diagnosis result for each combination is subdivided. A diagram showing the calculation processing flow of the controller (processor) 50 according to the third embodiment. A diagram showing the relationship between the leakage amount Q (horizontal axis) at a certain oil temperature and the corrected leakage amount QBase (vertical axis) at a reference temperature. A diagram showing the correction functions for the pressure drop time Ta and Tb associated with temperature change used by the controller 50. A calculation processing flow of the controller (processor) 50 according to the fourth embodiment. A functional block diagram explaining the processing performed by the processor of the controller 50 of the fifth embodiment, with each function being blocked. A calculation processing flow of the controller (processor) 50 according to the fifth embodiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a side view of a hydraulic excavator 1, which is one of the working machines according to an embodiment of the present invention.

[0010] The hydraulic excavator shown in this figure comprises a traveling body 101, a slewing body 102 that is rotatably mounted on the traveling body 101, and a front working device, or working device 103, that is attached to the slewing body 102.

[0011] The working device 103 includes a boom 104 attached to a slewing body 102 so as to be rotatable in the vertical direction, an arm 105 rotatably attached to the tip of the boom 104, and a bucket (attachment) 106 rotatably attached to the tip of the arm 105. The working device 103 also includes hydraulic cylinders such as a boom cylinder 33 for driving the boom 104, an arm cylinder 43 for driving the arm 105, and a bucket cylinder 53 for operating the bucket 106. An operator's cab 110 is provided at the front of the slewing body 102.

[0012] Figure 2 is a schematic diagram of a fault diagnosis system and related hardware according to an embodiment of the present invention.

[0013] The fault diagnosis system according to this embodiment includes a controller (control device) 50. The controller 50 is a computer having a processor (not shown) and a memory (not shown) that stores various data, including a program that defines the processing to be performed by the processor.

[0014] The controller 50 is connected to an operating lever 51 located in the operator's cab 110 to which the operator's operations on the hydraulic excavator (for example, a rotation operation on the slewing body 102 (hydraulic motor 40)) are input, an input device 52 that outputs a diagnosis start command to the controller 50 based on the operator's operation, a display 53 that displays information related to fault diagnosis (for example, the diagnosis result), a brake device 48 that brakes the hydraulic motor 40 that drives the slewing body 102, a pressure sensor (first pressure sensor) 47A provided in a pipeline 41A connected to the first input / output port (first intake / discharge port) 64a of the hydraulic motor 40, a pressure sensor (second pressure sensor) 47B provided in a pipeline 41B connected to the second input / output port (second intake / discharge port) 64b of the hydraulic motor 40, and solenoid valves 32A and 32B that drive a directional control valve 30 that controls the direction and flow rate of pressurized oil supplied to the hydraulic motor 40 via pipelines 41A and 41B.

[0015] The directional control valve 30 is connected to the hydraulic pump 20 via a pipeline 21. The pipeline 21 is equipped with a relief valve 35 to prevent the pressure in the pipeline 21 from rising above a predetermined pressure value (relief pressure), and a check valve 22. Pressurized oil discharged from the hydraulic pump 20 is supplied to the hydraulic motor 40 via the check valve 22, the directional control valve 30, and one of the two pipelines 41A and 41B. Pressurized oil returning from the hydraulic motor 40 via the other pipeline 41A and 41B is returned to the tank via the directional control valve 30.

[0016] The directional control valve 30 is a 3-position, 6-port switching valve and includes a spool 31 that switches the connection destination of each port according to the position, and spool operating sections 34A and 34B located at both ends in the axial direction of the spool 31, to which pilot pressure (drive signal) for operating the spool 31 is supplied. The directional control valve 30 has three positions: a first switching position (position A in Figure 2) that supplies pressurized oil to the first input / output port 64a of the two input / output ports 64a and 64b of the hydraulic motor 40; a second switching position (position B in Figure 2) that supplies pressurized oil to the second input / output port 64b; and a neutral position that shuts off the supply of pressurized oil to the two input / output ports 64a and 64b and also shuts off the discharge of the pressurized oil supplied to the two input / output ports 64a and 64b to the tank. The pilot pressure supplied to the spool operating sections 34A and 34B is generated by solenoid valves 32A and 32B, which operate based on an operation signal (a signal for switching the position of the spool 31) output from the controller 50 in response to the operation of the operating lever 51. Although the spool 31 shown in the figure is a hydraulic spool operated by pilot pressure, an electromagnetic spool operated by an electrical signal output from the controller 50 may also be used.

[0017] Each of the pipelines 41A and 41B is provided with an overload relief valve 44A, 44B and a check valve 46A, 46B, which prevent the pressure in each pipeline 41A, 41B from rising above a predetermined pressure value.

[0018] The pressure sensor 47A detects the pressure value of the pressurized oil supplied to the first input / output port 64a of the hydraulic motor 40 and outputs the signal to the controller 50. Similarly, the pressure sensor 47B also detects the pressure value of the pressurized oil supplied to the second input / output port 64b of the hydraulic motor 40 and outputs the signal to the controller 50.

[0019] The brake device 48 enters a braking state when a brake command is received from the controller 50 that has input a diagnostic start command, and applies braking force to the output shaft of the hydraulic motor 40 to mechanically stop and hold the slewing body 102. In the case where there is no diagnostic start command input (i.e., during normal brake control), the brake device 48 enters a braking state when the operating lever 51 is not operated, and applies braking force to the output shaft of the hydraulic motor 40 to stop and hold the slewing body 102. Furthermore, when the operating lever 51 is operated, the brake device 48 enters a brake release state based on a brake release command input from the controller 50, releasing the braking force and allowing the slewing body 102 to rotate.

[0020] In the normal rotation operation of the slewing body 102, the operator operates the control lever 51, which drives the solenoid valves 32A and 32B via the controller 50, thereby controlling the directional control valve 30. This supplies / discharges pressurized oil from the hydraulic pump 20 to the slewing motor 40, which drives the slewing motor 40 and moves the slewing body 102.

[0021] Next, we will explain the leakage of pressurized oil related to the drive of the hydraulic motor 40. Pressurized oil from the directional control valve 30 is supplied to each of the two pipelines 41A and 41B, but the components that can cause pressurized oil leakage related to the two pipelines 41A and 41B are the hydraulic motor 40, the overload relief valves 44A and 44B, and the check valves 46A and 46B. Here, the overload relief valves 44A and 44B and the check valves 46A and 46B are sometimes referred to as the hydraulic equipment related to the hydraulic motor 40. The overload relief valve 44A and the check valve 46A are connected to pipeline 41A, and the overload relief valve 44B and the check valve 46B are connected to pipeline 41B, so the leakage on the pipeline 41A side and the pipeline 41B side are independent.

[0022] On the other hand, the hydraulic motor 40 is connected to both of the two pipelines 41A and 41B, and damage to the hydraulic motor 40 may cause leaks from both pipelines 41A and 41B.

[0023] Figure 3 shows the cross-sectional structure of the hydraulic motor 40. The figure shows an example of an axial piston type hydraulic motor 40. The hydraulic motor 40 has a casing 62 which is made up of a cylindrical casing body 62a and a rear casing 62b. Inside the casing 62 are a valve plate 64, a cylinder block 69, a piston 70 inside the cylinder block 69, a shoe pad 75, a swash plate 63, and a shaft 65 which is the output shaft.

[0024] The valve plate 64 is approximately circular in shape and is fixed to the inner surface of the rear casing 62b. The valve plate 64 is equipped with a first input / output port 64a and a second input / output port 64b as input / output ports (intake / discharge ports) for the hydraulic fluid. The two input / output ports 64a and 64b are connected to the pipelines 41A and 41B, respectively, via the flow paths 62d and 62e provided within the rear casing 62b. The valve plate 64 also has a sealing surface 64c that slides against the sealing surface 69c of the cylinder block 69.

[0025] The cylinder block 69 is cylindrical and comprises a plurality of cylinders 69b arranged at equal intervals in the circumferential direction, and a piston 70 reciprocally housed within each cylinder 69b. Each cylinder 69b is connected to a cylinder port 69a opening in a sealing surface 69c. A substantially spherical recess is provided at the tip of each piston 70, and a shoe pad 75 having a spherical protrusion that can be fitted into the recess is rotatably coupled to the tip of the piston 70. Each shoe pad 75 is mounted in a support hole of a disc-shaped retainer 76. A sliding contact portion 74 is fixed to the shoe pad 75, and this sliding contact portion 74 is pressed against the swash plate 63. The swash plate 63 is mounted at a predetermined inclination angle with respect to the shaft 65 (when the hydraulic motor 40 is a fixed capacity type).

[0026] The rear casing 62b and the casing body 62a are each provided with bearings 66 and 67, respectively, and the shaft 65 is rotatably supported by these bearings 66 and 67. The shaft 65 has a protruding portion that extends outward through a hole provided in the casing body 62a, and this protruding portion is provided with spline teeth 65a that are coupled to the input shaft of a slewing drive device (not shown) that drives the slewing body 102 to slewing.

[0027] In the hydraulic motor 40 configured as described above, pressurized oil is introduced from the directional control valve 30, causing the piston 70, retainer 76, and shoe pad 75 to rotate. The shoe pad 75 presses against the swash plate 63, causing the cylinder block 69 to rotate and the shaft 65 to rotate. As a result of this operation, each sliding part slides, and oil is lubricated through the gaps between these sliding parts before being discharged to the drain. This results in leakage flow from a relatively high-pressure port (input / output port) to a relatively low-pressure port (input / output port). In this way, in the hydraulic motor 40, the sealing surface 69c of the cylinder block 69 is in contact with two conduits 41A and 41B (two input / output ports 64a and 64b). Therefore, if the sealing surface 69c wears down, leakage can occur in the two conduits 41A and 41B. Because of the existence of such a part, it is possible that pressurized oil may leak from both conduits 41A and 41B in the hydraulic motor 40.

[0028] As described above, in the hydraulic motor 40, there is a possibility of leakage occurring in the sliding parts between the cylinder block 69 and the valve plate 64, the sliding parts between the shoe pad 75 and the swash plate 63, and the sliding parts between the piston 70 and the cylinder block 69. In addition, there is a possibility of leakage occurring in related hydraulic equipment of the hydraulic motor 40, such as the overload relief valves 44A and 44B and the check valves 46A and 46B. In particular, the sliding conditions in the hydraulic motor 40 are severe, and if lubrication failure occurs during sliding, wear occurs, further increasing the gap between the sliding surfaces, and as a result, the amount of leakage may increase compared to the normal amount of leakage. Therefore, if the trend of increasing leakage can be grasped, it is thought that the wear condition of the motor sliding parts can be roughly estimated.

[0029] The relationship between the flow rate of pressurized oil in the pipelines 41A and 41B of the hydraulic motor 40 and the port pressure will be explained. Figure 4 shows an image of the leakage flow rate in the pipelines 41A and 41B from the directional control valve 30 to the hydraulic motor 40.

[0030] The relationship between the flow rates and pressures of the pressurized oil in pipeline 41A is expressed by the following equation (1).

[0031] The left side of equation (1) is the time derivative of the pressure at the first input / output port 64a (motor A port pressure Pa). On the right side of the same equation, QprefA is the flow rate of pressurized oil supplied from the pump 20 to the pipeline 41A (pump supply A flow rate), Qleak_motA is the leakage flow rate of pressurized oil occurring on the pipeline 41A side of the motor 40 (motor leakage A flow rate), Qleak_v1A is the flow rate of pressurized flow passing through the overload relief valve 44A (overload relief A flow rate), Qleak_v2A is the leakage flow rate of pressurized oil occurring at the check valve 46A (check valve leakage A flow rate), B is the bulk modulus of the pressurized oil (hydraulic oil), and V is the volume of the pipeline 41A (motor port pipeline volume). Note that only the pipeline 41A side is shown here, but the same applies to the pipeline 41B side.

[0032]

[0033] Here, as shown in equation (2) below, the leaks from each of the above devices 40, 44A, and 46A are added together and expressed as a single leak amount QleakA.

[0034]

[0035] Furthermore, if there is no flow rate A supplied by the pump from the directional control valve 30 (QprefA=0), equation (1) above can be expressed as equation (3) below using equation (2).

[0036]

[0037] Furthermore, assuming that the leakage amount QleakA in equation (2) is proportional to the motor A port pressure Pa, it can be expressed by equation (4) below. Here, KmA is the proportionality constant and is referred to as the leakage characteristic A.

[0038]

[0039] As a result, Equation (1) is derived from Equation (3) and Equation (4) to become the following Equation (5).

[0040]

[0041] Therefore, according to Equation (4), it can be understood that the leakage amount is proportional to the pressure Pa, and according to Equation (5), the pressure Pa is expressed in the form of a differential equation, and specifically exhibits characteristics of a first-order lag system. The pressure response characteristic (time constant T) at this time can be expressed as the following Equation (6).

[0042]

[0043] Therefore, if the pressure Pa of the first input / output port 64a can be measured and its response can be measured, the leakage characteristic A (KmA), which is an indicator of the leakage condition, can be indirectly estimated, and thereby the leakage amount (QleakA) can be estimated. In the present embodiment, based on this principle, the leakage amount (QleakA) is calculated from the temporal change of the pressure Pa.

[0044] In the above description, the pressure Pa is explained as the pressure of the input / output port 64a (64b) of the hydraulic motor 40, but the leakage amount (QleakA) may also be calculated using the pressure of the pipeline 41A (41B).

[0045] Fig. 5 is a functional block diagram illustrating processing executed by the processor of the controller 50, blocked by function.

[0046] As shown in this diagram, the controller 50 (processor) functions as a diagnostic operation command unit 81, a brake control unit 82, a directional control valve control unit 83, a pressure data collection unit 84, a time calculation unit 85, a determination unit 86, and a display / notification unit 87.

[0047] When the diagnostic operation command unit 81 receives a diagnostic start command from the input device 52, it executes the processing flow shown in Figure 6, etc., and sends commands to each unit as appropriate. That is, when a diagnostic start command is input, the diagnostic operation command unit 81 outputs operation commands to the brake control unit 82, the directional control valve control unit 83, the pressure data collection unit 84, the time calculation unit 85, and the determination unit 86. As a result, the brake control unit 82 outputs a brake command to the brake device 48 to hold the brake device 48 in the brake state. This forces the brake device 48 to operate and locks the rotation of the hydraulic motor 40. The directional control valve control unit 83 operates the solenoid valves 32A and 32B based on the input operation command to switch the position of the directional control valve 30. The pressure data collection unit 84 collects pressure data from the pressure sensors 47A and 47B connected to the first and second input / output ports 64a and 64b. The time calculation unit 85 measures the time during which the pressure data from the pressure sensors 47A and 47B satisfy the conditions described later. The determination unit 86 determines whether or not there are abnormal signs based on the time data calculated by the time calculation unit 85. The display / notification unit 87 sends a notification by displaying information on the display 53 or by sending an alarm command based on the determination result of the determination unit 86.

[0048] Figure 6 shows the calculation processing flow by the controller (processor) 50 according to the first embodiment.

[0049] When the operator inputs a diagnostic start operation to the input device 52, a diagnostic start command is output from the input device 52 to the controller 50. When this command is input to the controller 50, the flow shown in Figure 6 is started. The diagnostic start command may also be output to the controller 50 by the manager or service personnel of the hydraulic excavator 1.

[0050] In S101, the controller (processor) 50 outputs a brake command to the brake device 48, forcing the brake device 48 to operate. Upon receiving the brake command, the brake device 48 applies a braking force to the output shaft of the hydraulic motor 40, thereby locking the rotation of the hydraulic motor 40 and maintaining the stop of the slewing body 102.

[0051] In S102, the controller 50 outputs a drive signal (switching signal) to the solenoid valve 32A, which switches the spool 31 of the directional control valve 30 from the neutral position to position A (see Figure 2 (first switching position)), and the pressurized oil discharged from the pump 20 is introduced into the pipeline 41A. That is, with the hydraulic motor 40 held by the brake device 48, the supply of pressurized oil to the first input / output port 64a begins, and the pressure in the pipeline 41A increases.

[0052] In S103, the controller 50 receives the detection signal from the pressure sensor 47A on the first input / output port 64a side, calculates the pressure Pa at the first input / output port 64a, and determines whether the pressure is equal to or greater than the first threshold (first value) P1a. The first threshold P1a is a value less than or equal to the relief pressure of the overload relief valve 44A, and preferably a value close to the relief pressure, and in this embodiment, it is set to the relief pressure. If it is determined in S103 that Pa is equal to or greater than the first threshold P1a, the process proceeds to S104, and if it is determined that Pa is less than the first threshold P1a, the process is repeated in S103.

[0053] In S104, the controller 50 (1) starts recording (collecting) data of pressure Pa calculated from the output of the pressure sensor 47A into memory, (2) stops outputting the drive signal to the solenoid valve 32A which was started in S102, switches the spool 31 of the directional control valve 30 to the neutral position, and cuts off the supply of pressurized oil from the pump 20 to the first input / output port 64a, and further, (3) resets time Ta to zero and starts counting time Ta from the start of S104. Since the supply of pressurized oil is cut off in S104, the pressure Pa will decrease from the first threshold P1a according to the characteristics of the first-order lag system described above, and in the following S105, this pressure Pa will be monitored while data is collected. Note that in S104, the output of the drive signal to the solenoid valve 32A was stopped, but the controller 50 may also output a signal to the solenoid valve 32A (directional control valve 30) to switch the spool 31 of the directional control valve 30 to the neutral position.

[0054] In S105, the controller 50 determines whether the pressure Pa at the first input / output port 64a, based on the detection signal from the pressure sensor 47A, has dropped to a value less than or equal to the second threshold (second value) P2a.

[0055] Let's discuss the points to consider when determining the second threshold P2a. As mentioned above, the pressure Pa drop characteristic from S104 onwards is that of a first-order lag system, so the slope (time change of pressure) becomes smaller as the pressure decreases over time (see the bottom graph in Figure 8). In other words, the lower the pressure, the higher the pressure resolution and the better the pressure detection accuracy tends to be. However, it is important to note that if the slope is too small, the effect of pressure detection error will be large, and the smaller the slope, the longer it takes for the pressure to drop, which prolongs the measurement time Ta and reduces the diagnostic speed. Considering these points, it seems preferable to set the second threshold P2a in the range of pressure Pa change that excludes the range of 20% from the upper limit (i.e., the first threshold P1a) and the range of 10% from the lower limit (approximately 0 MPa) (i.e., 0.1 × P1a < P2a < 0.8 × P1a). The inventors have found that when the first threshold P1a is set to the relief pressure of the relief valve 44A, as in this embodiment, the second threshold P2a will fall within the range of 2-20 [MPa], depending on the size of the hydraulic excavator. In this embodiment, taking all of the above points into consideration, 10 [MPa], which is about one-third of the first threshold P1a, which is the upper limit of the pressure Pa, is adopted as the second threshold P2a. If it is determined in S105 that the pressure Pa is less than or equal to the second threshold P2a, the process proceeds to S106, and if it is determined that the pressure Pa is greater than the second threshold P2a, S105 is repeated.

[0056] In S106, the controller 50 finishes measuring time Ta, calculates the time (first time) Ta required from the time the supply of pressurized flow to the first input / output port 64a was cut off in S104 until the pressure Pa dropped to the second threshold P2a, and then finishes recording (collecting) the pressure Pa data to memory, which was started in S104.

[0057] In S107, it is determined whether the time Ta calculated in S106 is less than the threshold (first time threshold) T1a. Time Ta is the time required for the pressure Pa to drop from the first threshold P1a to the second threshold P2a, and tends to be shorter than in the normal case (when there is no leak) if a pressurized oil leak is occurring. In other words, the threshold T1a is a value used to determine whether or not a leak is occurring. If it is determined in S107 that time Ta is less than the threshold T1a, it is determined that there are signs of an abnormality in the hydraulic motor 40 and its related hydraulic equipment (S108), and the controller 50 outputs an abnormality notification command to notify notification devices such as the display 53 and speaker of the abnormality (S109). As a result, the diagnosis result of the abnormality is displayed on the display 53, and the abnormality is notified via the speaker. In this case, the controller 50 determines that there is a possibility of a leak occurring in the hydraulic motor 40 connected to the pipeline 41A and in either the relief valve 44A or the check valve 46A, which are related hydraulic equipment, and that there are signs of an abnormality in these.

[0058] On the other hand, if it is determined in S107 that the time Ta is equal to or greater than the threshold T1a, the hydraulic motor 40 and its related hydraulic equipment (relief valve 44A and check valve 46A) are determined to be normal (S110), and the controller 50 outputs a normal notification command to notify a notification device such as a display 53 or speaker of this fact (S111). Note that the determination in S110 and the notification in S111 may be omitted.

[0059] After executing S109 or S111, the series of processes shown in Figure 6 is terminated. However, at the end of the flow in Figure 6, it is preferable to release the forced activation of the brake device 48 performed in S101 and return to normal brake control.

[0060] Through the above process, it is possible to measure the time Ta related to the change in pressure Pa at the input / output port 64a side of the pipeline 41A, estimate the degree of leakage based on the magnitude of this time Ta, and diagnose any abnormal trends. This diagnostic result is output via the display 53 or speaker.

[0061] Next, the change in pressure Pa at the first input / output port 64a of the hydraulic motor 40 when the controller 50 is operated according to the flow chart in Figure 6 will be explained using Figures 8 and 9.

[0062] Figure 8 shows an example of the waveforms of the pressure acting on the operating section 34A of the directional control valve 30 (directional control valve pilot pressure), the pressure of the pump 20 (pump pressure), and the pressure Pa (motor port pressure) of the first input / output port 64a of the motor 40 when the controller 50 is operated according to the flow in Figure 6.

[0063] In S102, pressure (pilot pressure) is applied to the operating section 34A to switch the directional control valve 30 to position A (first switching position), and consequently, the pump pressure and motor port pressure Pa rise to the relief pressure.

[0064] In S104, the directional control valve 30 is returned to the neutral position, and the pump pressure transitions to the standby pressure. At the same time, the motor port pressure Pa is in the relief pressure state, and the directional control valve 30 disconnects it from the pump 20. The time at this point becomes the initial value T0 = 0 for time measurement.

[0065] In S105, when the detected motor port pressure Pa is determined to be at the second threshold P2a, the time measurement count value Ta = T1 is determined in S106. Time T1 is a value greater than or equal to the threshold T1a, and is determined to be normal in S110. In other words, Figure 8 shows the pressure waveform under normal conditions. Note that the motor port pressure Pa eventually converges to the tank pressure (≈0.02 [MPa]) over time.

[0066] On the other hand, Figure 9 shows an example of a pressure waveform when leakage increases (when there are signs of abnormality).

[0067] The waveform of the motor port pressure Pa in Figure 9 represents the case where pressurized oil leakage has increased compared to the normal case in Figure 8. As shown by the dashed line in the graph, the pressure drop after T0 is rapid. As a result, the time T1' in the case of increased leakage in Figure 9 is shorter than the time T1 in the normal case. This difference in time represents a difference in the amount of leakage, indicating that the leakage is greater. In other words, it can be seen that wear on the motor 40 and other components is more advanced in the case of Figure 9. The relationship with the specific leakage characteristics is as shown in the equation above.

[0068] In this embodiment, the time Ta required for the pressure at the input / output port 64a of the hydraulic motor 40 to drop from a first threshold (e.g., relief pressure) to a second threshold can be determined. This time Ta can then be used as a feature to determine whether or not there are signs of abnormality. As a result, the degree of leakage in the hydraulic motor 40 and its related hydraulic equipment can be accurately determined, making it possible to detect signs of abnormality such as wear in the hydraulic motor 40 at an early stage.

[0069] Furthermore, although the above describes how the on-board controller 50 diagnoses the presence or absence of a malfunction, it is also possible to transfer feature quantities representing the malfunction state (for example, time Ta, first threshold P1a, second threshold P2a, model of the work machine, operating time, etc.) to a server (analysis server) installed at another location using communication means such as satellite communication, and perform the process of determining the presence or absence of a malfunction and setting the time threshold T1a while considering the feature quantity data of other work machines. A schematic diagram of the configuration in that case is shown in Figure 7.

[0070] Figure 7 is a schematic diagram of a server-based anomaly diagnosis. In this example, feature quantities such as time Ta calculated by the work machine are transferred to the server, and the server determines the presence or absence of anomaly signs by comparing these feature quantities with corresponding thresholds. Furthermore, since it is easy to compare with data from other machines that have been similarly transferred to the server, it is also possible to determine "anomaly signs present" based on the degree of deviation from this aggregate data. In addition, instead of a binary evaluation of present / absent, it is preferable to classify the results into multiple levels and display / notify the results as an anomaly severity level, thereby conveying the level of the anomaly. Upon receiving such diagnostic results, the server can notify service personnel, users, administrators, etc., enabling rapid maintenance and reducing the risk due to failure.

[0071] <Second Embodiment> Next, a second embodiment will be described. This embodiment is a modified version of the calculation processing of the controller 50, and is characterized in that, in addition to calculating the time Ta required for the change in pressure Pa at the first input / output port 64a, it also calculates the time Tb required for the change in pressure Pb at the second input / output port 64b, and diagnoses whether or not there are any abnormal signs related to the two input / output ports 64a and 64b.

[0072] Figure 10 shows the calculation processing flow by the controller (processor) 50 according to the second embodiment. The same reference numerals are used for the same processes as in Figure 6, and the explanation of such processes may be omitted.

[0073] After calculating time Ta in S106 and completing data collection for pressure Pa, the controller 50 executes the process in S202.

[0074] In S202, the controller 50 outputs a drive signal (switching signal) to the solenoid valve 32B, which switches the spool 31 of the directional control valve 30 from the neutral position to position B (see Figure 2 (second switching position)), and the pressurized oil discharged by the pump 20 is introduced into the pipeline 41B. That is, with the hydraulic motor 40 held by the brake device 48, the supply of pressurized oil to the second input / output port 64b begins, and the pressure in the pipeline 41B increases.

[0075] In S203, the controller 50 receives the detection signal from the pressure sensor 47B on the second input / output port 64b side, calculates the pressure Pb at the second input / output port 64b, and determines whether the pressure is equal to or greater than the third threshold (third value) P1b. The third threshold P1b is a value less than or equal to the relief pressure of the overload relief valve 44B, preferably a value close to the relief pressure, and in this embodiment, it is set to the relief pressure, and is the same value as the first threshold (first value) P1a related to the first input / output port 64a. If it is determined in S203 that Pb is equal to or greater than the third threshold P1b, the process proceeds to S204, and if it is determined that Pb is less than the third threshold P1b, the process is repeated in S203.

[0076] In S204, the controller 50 (1) starts recording (collecting) data of pressure Pb calculated from the output of the pressure sensor 47B into memory, (2) stops outputting the drive signal to the solenoid valve 32B which was started in S202, switches the spool 31 of the directional control valve 30 to the neutral position, and cuts off the supply of pressurized oil from the pump 20 to the second input / output port 64b, and further, (3) resets time Tb to zero and starts counting time Tb from the start of S204. Since the supply of pressurized oil is cut off in S204, the pressure Pb will decrease from the third threshold P1b according to the characteristics of the first-order lag system described above, and in the following S205, this pressure Pb will be monitored while data is collected. Note that in S204, the output of the drive signal to the solenoid valve 32B was stopped, but the controller 50 may also output a signal to the solenoid valve 32B (directional control valve 30) to switch the spool 31 of the directional control valve 30 to the neutral position.

[0077] In S205, the controller 50 determines whether the pressure Pb at the second input / output port 64b, based on the detection signal from the pressure sensor 47B, has dropped to a value less than or equal to the fourth threshold (fourth value) P2b. The fourth threshold P2b is preferably determined by considering the same points as the second threshold P2a related to the first input / output port 64a, and in this embodiment, it is set to the same value as the second threshold P2a.

[0078] If it is determined in S205 that the pressure Pb is less than or equal to the fourth threshold P2b, the process proceeds to S206. If it is determined that the pressure Pb is greater than the fourth threshold P2b, the process is repeated in S205.

[0079] In S206, the controller 50 finishes measuring time Tb, calculates the time (second time) Tb that was taken from the time the supply of pressurized flow to the second input / output port 64b was cut off in S204 until the pressure Pb dropped to the fourth threshold P2b, and then finishes recording (collecting) the pressure Pb data into memory, which was started in S204.

[0080] If the controller 50 determines in S107 that time Ta is equal to or greater than the threshold T1a, the process proceeds to S207.

[0081] In S207, it is determined whether the time Tb calculated in S206 is less than the threshold (second time threshold) T1b. If it is determined that the time Tb is less than the threshold T1b, it is determined that there are signs of an abnormality in the hydraulic motor 40 and its related hydraulic equipment (S108), and the controller 50 outputs an abnormality notification command to notify notification devices such as the display 53 and speaker of the abnormality (S109). As a result, the diagnosis result of the abnormality is displayed on the display 53, and the abnormality is notified via the speaker. In this case, the controller 50 determines that there is a possibility of a leak in either the hydraulic motor 40 connected to the pipeline 41B or its related hydraulic equipment, the relief valve 44B and the check valve 46B, and that there are signs of an abnormality in these.

[0082] On the other hand, if it is determined in S207 that time Tb is greater than or equal to threshold T1b, the hydraulic motor 40 and its related hydraulic equipment (relief valves 44A, 44B and check valves 46A, 46B) are determined to be normal (S110), and the controller 50 outputs a normal notification command to notify a notification device such as a display 53 or speaker of this fact (S111). Note that the determination in S110 and the notification in S111 may be omitted.

[0083] According to the above embodiment, it is possible to diagnose at once whether or not there are any signs of abnormality in the two input / output ports 64a and 64b provided in a normal hydraulic motor.

[0084] <Third Embodiment> Next, a third embodiment will be described. In the second embodiment, the abnormal trend at each port was grasped by simply evaluating the pressure drop characteristics of the two input / output ports 64a and 64b, but it was not possible to determine which device on which port side was malfunctioning. Therefore, in this embodiment, the abnormal part can be identified as precisely as possible from the combination of diagnostic results for each port.

[0085] As mentioned above, the hydraulic motor 40 has a structure in which the cylinder block 69 rotates, and each cylinder 69b connects to two conduits 41A and 41B that open into the valve plate 64. Due to this structure, if the sealing surface 69c of the cylinder block 69 wears down and a gap is formed between it and the sealing surface 64c of the valve plate 64, there is a high possibility that leakage will occur in both conduits 41A and 41B. In contrast, the overload relief valve 44A is connected only to the conduit 41A side, and the overload relief valve 44B is connected only to the conduit 41B side, so even if leakage occurs in either of them, it will only be leakage in the respective conduits 41A and 41B. Similarly, the check valves 46A and 46B are connected only to the conduit 41A side, and the check valve 46B is connected only to the conduit 41B side, so even if leakage occurs in either of them, it will only be leakage in the respective conduits 41A and 41B. By utilizing this, it is possible to estimate to some extent the location of the abnormality based on the pressure drop times Ta and Tb, which are used to calculate the amount of leakage from pipelines 41A and 41B. An example of the combination of leakage magnitude and the location of the abnormality is shown in Figure 11.

[0086] Figure 13 shows the calculation processing flow by the controller (processor) 50 according to the third embodiment. However, the flow starts from S101 in Figure 10, and after executing up to S206 in Figure 10, S301 in Figure 13 is executed. Note that the same reference numerals are used for the same processes as in Figure 10, and the explanation of such processes may be omitted.

[0087] In S301, the controller 50 determines whether the time Ta calculated in S106 is less than the threshold (first time threshold) T1a, and whether the time Tb calculated in S206 is greater than or equal to the threshold (second time threshold) T1b. If the determination is YES, the process proceeds to S302, where it is determined that there is an abnormality in at least one of the valves on the pipeline 41A side, namely the relief valve 44A and the check valve 46A, and the process proceeds to S109. On the other hand, if the determination is NO, the process proceeds to S303.

[0088] In S303, the controller 50 determines whether time Ta is greater than or equal to the threshold (first time threshold) T1a, and time Tb is less than the threshold (second time threshold) T1b. If the determination is YES, the process proceeds to S304, where it determines that there is an abnormality in at least one of the valves on the pipeline 41B side, namely the relief valve 44B and the check valve 46B, and proceeds to S109. On the other hand, if the determination is NO, the process proceeds to S305.

[0089] In S305, the controller 50 determines whether time Ta is less than the threshold (first time threshold) T1a and time Tb is less than the threshold (second time threshold) T1b. If the determination is YES, the process proceeds to S306, where it is determined that there is an abnormality in the hydraulic motor 40, and the process proceeds to S109. On the other hand, if the determination is NO, the process proceeds to S110.

[0090] In S109, a notification is sent via a notification device such as a display 53 or speaker to inform the user that there is an abnormality in the part that was determined to have an abnormality in the previous step (i.e., in any of S302, 304, or 306).

[0091] According to the above embodiment, it is possible to determine whether the abnormality is in one of the valves in the two pipelines 41A or 41B, or in the hydraulic motor 40. This allows for prompt action after the abnormality is detected, thereby suppressing an increase in the downtime of the hydraulic excavator 1.

[0092] In the example above, time intervals Ta and Tb were each divided into two categories (large and small), resulting in a total of 2 x 2 = 4 patterns for classifying the diagnostic results. However, each time interval (Ta) and Tb can be divided into three or more categories based on their length. For example, Figure 12 divides each time interval (Ta) and Tb into five categories, resulting in a total of 5 x 5 = 25 patterns for classifying time combinations and further subdividing the degree of risk in each diagnostic result.

[0093] <Fourth Embodiment> Next, a fourth embodiment will be described. Since excavators and other work machines are used outdoors, the temperature of the hydraulic fluid may change depending on the climate and season of the work environment, or the operating conditions. When the temperature of the hydraulic fluid changes, its viscosity also changes, and consequently, the leakage flow rate may also change to some extent. Therefore, in this embodiment, the accuracy of abnormality detection is improved by correcting the time Ta and Tb according to the temperature.

[0094] The relationship between temperature and leakage rate is explained below. Fluids such as hydraulic fluid have viscosity. The fluidity of hydraulic fluid decreases at low temperatures and increases at high temperatures. In other words, viscosity tends to decrease as temperature increases (downward trend).

[0095] The flow rate Qc of a choke constrictor, which is susceptible to viscosity, can generally be expressed by the following equation (7). Here, μ is the viscosity of the hydraulic fluid, D is the inner diameter of the pipe, and L is the length of the pipe.

[0096]

[0097] This assumes flow within a straight circular pipe with a constant cross-sectional area, diameter D, and length L. It represents a relatively long constriction relative to the cross-sectional dimensions, and the relationship is based on the assumption that pressure loss occurs due to the fluid's viscous resistance. According to this equation, the flow rate is proportional to the reciprocal of the viscosity μ (1 / μ).

[0098] On the other hand, the flow rate Qo of an orifice that is not affected by viscosity can generally be expressed by the following equation (8). Here, A is the opening area, ρ is the hydraulic fluid density, and C is the flow coefficient.

[0099]

[0100] This assumes a flow ejected from a hole in a relatively thin plate. It is based on the image of a short constriction, a sharp-edge orifice, and the relationship is one in which pressure loss occurs due to vortices in the fluid jet. According to this equation, it is not affected by viscosity, such as choke. Therefore, while a choke constriction is affected by temperature, an orifice constriction is not. In the actual configuration of hydraulic components, these are combined (combined), so it is thought to have characteristics somewhere between the two, and is not affected as much as a complete choke constriction, but is thought to be affected by temperature to some extent.

[0101] Figure 14 shows the relationship between the leakage amount Q at a certain oil temperature (horizontal axis) and the corrected leakage amount QBase at a reference temperature (vertical axis). The corrected leakage amount QBase, calculated assuming the reference temperature, is calculated based on a function that takes the leakage amount Q at a certain temperature as input and has a tendency for its slope to increase with temperature. In other words, by having a pre-established correspondence between the corrected leakage amount QBase and the leakage amount Q at the measured temperature as a characteristic of this function, it becomes possible to convert the calculated leakage amount at any temperature to the leakage amount at the reference temperature.

[0102] When performing the conversion in controller 50, the relationship between the pressure drop time T and the temperature Temp, as defined by equation (9) below, is used to add a temperature-dependent correction to the pressure drop time using the function shown in Figure 15. In equation (9), T is the pressure drop time, Q is the leakage flow rate, μ is the viscosity, and Temp (deg) is the temperature. That is, the slope of the conversion function tends to decrease as the temperature increases. This function can also be configured with high accuracy by pre-measuring and setting its characteristics with temperature.

[0103] Figure 15 shows the correction function for pressure drop times Ta and Tb associated with temperature changes, which is used by the controller 50. The controller 50 corrects the calculated pressure drop times Ta and Tb using, for example, the temperature obtained from an on-board temperature sensor and the table in Figure 15. This function converts the time calculated at oil temperature to the time at a reference temperature.

[0104]

[0105] Figure 16 shows the arithmetic processing flow by the controller (processor) 50 according to the fourth embodiment. This processing flow corresponds to a modified version of the first embodiment (Figure 6), with S106A and S107A being changed. The same processing as in the flow of Figure 6 will not be explained.

[0106] In S106A, the controller 50 finishes measuring time Ta and calculates the time (first time) Ta that was taken from the time the supply of pressurized flow to the first input / output port 64a was cut off in S104 until the pressure Pa dropped to the second threshold P2a. Furthermore, it finishes recording (collecting) the pressure Pa data that was started in S104 into memory. It also receives a detection signal from an onboard temperature sensor (not shown), calculates the current temperature based on the detection signal, and uses that temperature and the correction function in Figure 15 to correct time Ta and calculate the corrected time (corrected time) Ta'. For example, if the temperature calculated in S106A is higher than the reference temperature, the corrected time Ta' will be shorter than the time Ta before correction.

[0107] In S107A, the controller 50 determines whether the correction time Ta' calculated in S106A is less than the threshold (first time threshold) T1a. The subsequent processing is the same as in Figure 6, so the explanation is omitted.

[0108] As described above, by correcting time Ta according to temperature, the leakage amount at the reference temperature can be calculated and evaluated even when the hydraulic fluid temperature conditions differ during the diagnostic process. This makes it possible to suppress the effects of changes in leakage flow rate due to temperature changes, even when the hydraulic fluid temperature differs significantly from the reference temperature due to the working environment of the hydraulic excavator.

[0109] In the above example, temperature was obtained (calculated) from an on-board temperature sensor, but the time Ta may also be corrected by inputting temperature data from the site where the hydraulic excavator 1 is operating from an external source using wireless communication or the like. Furthermore, it goes without saying that the time correction using temperature in this embodiment can also be used in other embodiments other than the first embodiment.

[0110] <Fifth Embodiment> Next, a fifth embodiment will be described. Each embodiment described so far employs a method in which a diagnostic start command is triggered, and a predetermined series of operations for calculating time Ta(Tb) are performed in accordance with commands from the controller 50. This method has advantages such as being able to obtain highly accurate and stable calculation results because the optimal operations for calculating time Ta(Tb) are performed. However, since it is necessary to force the shovel to perform a predetermined series of operations, the operator's work must be interrupted during that time. Therefore, in this embodiment, even during operator operation, time Ta(Tb) is automatically calculated when the conditions necessary for calculating time Ta(Tb) are met, thereby suppressing the occurrence of work interruptions.

[0111] Figure 17 is a functional block diagram illustrating the processes executed by the processor of the controller 50 in this embodiment, broken down into functional blocks.

[0112] The controller 50 is communicatively connected to a mode selection switch 95 used to select an automatic diagnostic mode for automatically starting fault diagnosis, pressure sensors 47A and 47B provided in the pipelines 41A and 41B, a slewing operation lever 51s to which the operator inputs slewing operations for the slewing body 102 (hydraulic motor 40), a rotation speed sensor 96 for detecting the rotation speed of the hydraulic motor 40, a brake device 48 for braking the hydraulic motor 40 and maintaining a stopped state, a display 53 for displaying diagnostic information, and an alarm for notifying diagnostic warnings.

[0113] The controller 50 (processor) of this embodiment functions as follows: a mode determination unit 88 that determines whether an automatic diagnostic mode is selected based on a signal from a mode selection switch 95; a slewing operation detection unit 89 that detects a slewing operation based on an operation signal output from a slewing operation lever 51s; a motor stop determination unit 90 that determines whether the hydraulic motor 40 is stopped based on a detection signal from a rotation speed sensor 96; a pressure data collection unit 84 that collects the pressure of pipelines 41A and 41B based on detection signals from pressure sensors 47A and 47B; a brake control unit 82 that controls the brake device 48 based on the operation of the slewing operation lever 51s; a time calculation unit 85 that calculates times Ta and Tb based on the pressure changes in pipelines 41A and 41B and the state of the slewing body 102; a determination unit 86 that determines whether there is an abnormality based on the times Ta and Tb; and a display / notification unit 87 that displays and notifies the diagnostic results. Parts with the same reference numerals as in Figure 5 have generally the same functions as those in Figure 5, and the explanation of such functions may be omitted.

[0114] When there is an operation input to the slewing operation lever 51s, the brake control unit 82 outputs a brake release command to the brake device 48, putting the brake device 48 into a brake release state. On the other hand, when there is no such operation input (in this case, the directional control valve 30 is switched to the neutral position), the brake device 48 enters a braking state and applies braking force to the output shaft of the hydraulic motor 40 to stop and hold the slewing body 102.

[0115] The slewing operation detection unit 89 is the part that detects input operations to the slewing operation lever 51s. Input operations to the slewing operation lever 51s can be detected, for example, by the pilot pressure generated when the slewing operation lever 51s is operated, in the case of a hydraulic pilot type. If the operation lever 51s is electrically operated, it can be detected by the operation signals output to the solenoid valves 32A and 34B.

[0116] The motor stop determination unit 90 determines whether the hydraulic motor 40 is stopped based on the rotational speed of the hydraulic motor 40 detected by the rotational speed sensor 96. In a typical hydraulic excavator, the slewing body 102 stops about one second after the slewing operation lever 51s is moved to the neutral position. Therefore, it is also possible to determine that the hydraulic motor 40 is stopped if the slewing operation lever 51s remains in the neutral position for a predetermined time (for example, any value between one and three seconds). In this case, the rotational speed sensor 96 can be omitted from the system.

[0117] Figure 18 shows the calculation processing flow by the controller (processor) 50 according to the fifth embodiment. This flow can be initiated, for example, by a vehicle request such as the hydraulic excavator engine being started and the vehicle body becoming operational. The same reference numerals are used for the same processes as those described in the previous flow, and the explanation of such processes may be omitted as appropriate.

[0118] In S501, the controller 50 determines whether the automatic diagnostic mode is selected based on the signal from the mode selection switch 95. If the automatic diagnostic mode is selected, the process proceeds to S502; otherwise, the process ends.

[0119] In S502, the controller 50 starts recording (collecting) data of pressure Pa calculated from the output of pressure sensor 47A and data of pressure Pb calculated from the output of pressure sensor 47B into memory.

[0120] In S503, the controller 50 determines whether the current values ​​of pressure Pa and pressure Pb are different. If they are different, it proceeds to S504; otherwise, it repeats the determination in S503.

[0121] In S504, the controller 50 determines whether pressure Pa is greater than pressure Pb. When the directional control valve 30 is switched to position A by operating the swivel lever 51s, the supply of pressurized oil to the first input / output port 64a begins, and pressure Pa becomes greater than pressure Pb. If pressure Pa is greater than pressure Pb, the process proceeds to S505; otherwise, it returns to S503.

[0122] In S505, the controller 50 determines whether three conditions are met: the pressure Pa is equal to or greater than the fifth threshold P3a, the slewing lever 51s is in the neutral position, and the hydraulic motor 40 is stopped.

[0123] The fifth threshold P3a in the first condition is the high-pressure side pressure value that serves as the starting point for measuring time Ta. This value P3a should be set to be less than or equal to the upper limit of the pressure that can be generated in the hydraulic system related to the hydraulic motor 40, and it is preferable to set it to a value less than or equal to the relief pressure. For example, it may be set slightly lower than the relief pressure (-1 [MPa]) (i.e., so that the actual pressure Pa reaches P3a).

[0124] Regarding the second condition, whether or not the slewing lever 51s is in the neutral position can be determined by using the detection signal from the operating amount sensor of the slewing lever 51s, or by using the operating signal output by the operation of the slewing lever 51s. When the slewing lever 51s is in the neutral position, the directional control valve 30 is also switched to the neutral position. This cuts off the supply of pressurized oil to the first input / output port 64a, and after the hydraulic motor 40 is braked by the brake device 48, its rotation is locked.

[0125] Regarding the third condition, whether or not the hydraulic motor 40 is stopped can be confirmed using the detection signal from the rotation speed sensor 96, as described above, or by confirming that a predetermined time has elapsed since the slewing operation lever 51s was held in the neutral position.

[0126] One scenario in which these three conditions are met is when a full rotation operation is performed on the rotation control lever 51s in either the left or right direction, and then the rotation control lever 51s is returned to the neutral position to stop the rotation body 102. In this case, the rotation control lever is in the neutral position when the pressure Pa reaches the relief pressure, and the hydraulic motor 40 is stopped.

[0127] If it is determined that the above three conditions are met, proceed to S506; otherwise, return to S503.

[0128] In S506, the controller 50 resets time Ta to zero and starts counting time Ta from the start of S506, then proceeds to S507.

[0129] In S507, the controller 50 determines whether the pressure Pa at the first input / output port 64a, based on the detection signal from the pressure sensor 47A, has dropped to a value less than or equal to the sixth threshold P4a. The sixth threshold P4a is a predetermined reference pressure, similar in purpose to the second threshold P2a in the first embodiment, and is a pressure value smaller than the fifth threshold P3a. It may also be the same value as the second threshold P2a in the first embodiment.

[0130] If it is determined in S507 that the pressure Pa is less than or equal to the sixth threshold P4a, the process proceeds to S106. If it is determined that the pressure Pa is greater than the sixth threshold P4a, the process is repeated in S507.

[0131] The process from S106 onward has already been explained in the flowchart in Figure 6, so the explanation will be omitted here.

[0132] Next, the operation of this embodiment will be described.

[0133] In the system configured as described above, when the hydraulic excavator engine is started, the controller 50 starts the flow shown in Figure 18. Then, if the automatic diagnostic mode is selected with the mode selection switch 95 (S501), the controller 50 starts collecting pressure Pa, Pb data from the pipelines 41A and 41B via the two pressure sensors 47A and 47B (S502).

[0134] The controller 50 checks whether pressure Pb and pressure Pa are different and whether pressure Pa is greater than pressure Pb (S503, 504). When these two conditions are met, pressurized oil is supplied from the hydraulic pump 20 to the first input / output port 64a of the hydraulic motor 40 and the slewing body 102 is slewing. In other words, the slewing operation lever 51s is operated and the hydraulic motor 40 is rotating.

[0135] Once the above conditions are confirmed, the controller 50 checks whether the pressure Pa is equal to or greater than the fifth threshold P3a (for example, the relief pressure of the relief valve 44A), whether the swivel operation lever 51s is operated to the neutral position, and whether the rotation speed of the hydraulic motor 40 has become 0 (S505). This condition is one in which the pressure in the pipeline 41A has risen to P3a or higher due to the swivel operation, the swivel operation lever 51s is operated to the neutral position, and the rotation of the hydraulic motor 40 has subsequently stopped. When the swivel operation lever 51s is returned to the neutral position, the controller 50 stops outputting a brake release command to the brake device 48, which switches the brake device 48 to the brake state, and soon the brake device 48 holds the hydraulic motor 40 stopped. In other words, when the pressure in the pipeline 41A is P3a or higher, the swivel operation lever 51s is returned to the neutral position, and the three conditions related to S505 are met.

[0136] If the determination related to S505 is affirmed, the controller 50 starts measuring time Ta (S506). Subsequently, the pressure Pa in the pipeline 41A decreases from P3a over time, and the controller 50 checks whether Pa has fallen below the sixth threshold P4a (S507). Once this is confirmed, the controller 50 ends the measurement of time Ta and also ends the collection of pressure data related to Pa and Pb (S106). As a result, the measurement of time Ta is automatically completed, and a fault diagnosis of the hydraulic motor 40 and its related hydraulic equipment is performed based on the measured time Ta and threshold T1a.

[0137] Although the above describes the procedure for diagnosing abnormalities in pipeline 41A, pipeline 41B can also be diagnosed using the same flow. For example, if it is determined in S504 that pressure Pb is greater, the same processing as in S505 onwards should be performed for pipeline 41B.

[0138] As described above, by using the automatic diagnostic mode, when the measurement conditions for time Ta(Tb) are met while the operator is operating the hydraulic excavator, time Ta(Tb) is automatically measured and a diagnosis is performed. This eliminates the need to interrupt work to perform a diagnosis, thus suppressing a decrease in work efficiency. Furthermore, since manual diagnosis is no longer required, problems such as the progression of abnormalities due to neglecting diagnosis over a long period can be avoided. Even if the number of managed work machines increases, there is no need to rely on operators or service personnel, so a stable and highly efficient monitoring operation and service system can be established.

[0139] <Summary> The characteristics of each embodiment described above can be extracted and summarized as follows.

[0140] (1) A fault diagnosis system for a hydraulic motor (40) and related hydraulic equipment (44A, 46A) mounted on a work machine (hydraulic excavator 1) comprises: a brake device (48) for braking the hydraulic motor (40); a directional control valve (30) having a first switching position for supplying pressurized oil to the first input / output port (64a) of the two input / output ports (64a, 64b) of the hydraulic motor (40), and a neutral position for shutting off the supply of pressurized oil to the two input / output ports (64a, 64b) and shutting off the discharge of the pressurized oil supplied to the two input / output ports (64a, 64b) to the tank; a first pressure sensor (47A) for detecting the pressure of the pressurized oil supplied to the first input / output port (64a); and a control device (50) for controlling the directional control valve (30). When a diagnostic start command is input, the control device (50) outputs a brake command to the brake device (48) to lock the rotation of the hydraulic motor (40), outputs a switching signal to the directional control valve (30) to switch the directional control valve (30) to the first switching position so that pressurized oil is supplied to the first input / output port (64a), and when the first pressure sensor (47A) detects that the pressure (Pa) at the first input / output port has reached a first value (P1a), the control device (50) outputs a signal to the directional control valve (30) to switch the directional control valve (30) to the neutral position to shut off the supply of pressurized oil to the first input / output port (64a), calculates the first time (Ta) taken from the start of the shutdown of the supply of pressurized oil until the pressure (Pa) at the first input / output port (64a) drops to a second value (P2a), and causes the processor to execute a process to detect signs of abnormality in the hydraulic motor and its related hydraulic equipment based on the first time (Ta).

[0141] In this way, by monitoring the pressure (Pa) change at the first input / output port of the two input / output ports (64a, 64b) related to the hydraulic motor (40), and calculating the time (first time (Ta)) required for the pressure (Pa) to change from a first value (P1a) to a second value (P2a) under predetermined conditions, the amount of leakage occurring in the hydraulic motor (40) and its related hydraulic equipment (44A, 46A) related to one of the two input / output ports (64a, 64b) can be indirectly determined. As a result, even in a system equipped with a single hydraulic motor (40), the presence or absence of abnormal signs in the hydraulic motor (40) and its related hydraulic equipment (44A, 46A) can be detected with high accuracy.

[0142] (2) In the above (1), preferably, the control device (50) determines that there is an abnormality in at least one of the hydraulic motor (40) and the hydraulic equipment (44A, 46A) on the first input / output port side when the first time (Ta) is less than the first time threshold (T1a).

[0143] Thus, when the first time (Ta) is less than the first time threshold (T1a), it can be determined that there is an abnormality in at least one of the hydraulic motor (40) and the hydraulic equipment (44A, 46A) on the first input / output port side.

[0144] (3) In any one of (1) to (2) above, preferably the directional control valve (30) has a second switching position that supplies pressurized oil to the second input / output port (64b) of the two input / output ports (64a, 64b), and further comprises a second pressure sensor (47B) that detects the pressure of the pressurized oil supplied to the second input / output port (64b). After calculating the first time (Ta), the control device (50) outputs a switching signal to the directional control valve (30) and switches the directional control valve (30) to the second switching position so that pressurized oil is supplied to the second input / output port (64b) of the two input / output ports (64a, 64b). When the second pressure sensor (47B) detects that the pressure (Pb) at the second input / output port (64b) has reached the third value (P1b), the control device (50) outputs a signal to the directional control valve (30) to switch it to the neutral position, thereby cutting off the supply of pressurized oil to the second input / output port (64b). The second time (Tb) is calculated from the time the supply is cut off until the pressure at the second input / output port (64b) decreases to the fourth value (P2b). When at least one of the following conditions is met: the first time (Ta) is less than the first time threshold (T1a) and the second time (Tb) is less than the second time threshold (T1b), it is determined that there is an abnormality in one of the hydraulic motor (40), the hydraulic equipment (44A, 46A) on the first input / output port (64a) side, and the hydraulic equipment (44B, 46B) on the second input / output port (64b) side.

[0145] By calculating the second time in this way and comparing it with the second time threshold (T1b), it can be determined that there is an abnormality in one of the following: the hydraulic motor (40), the hydraulic equipment on the first input / output port (64a) side (44A, 46A), or the hydraulic equipment on the second input / output port (64b) side (44B, 46B).

[0146] (4) In the above (3), preferably, the control device (50) determines that there is an abnormality in the hydraulic equipment (44A, 46A) on the first input / output port (64a) side when the first time (Ta) is less than the first time threshold (T1a) and the second time (Tb) is greater than or equal to the second time threshold (T1b), and determines that there is an abnormality in the hydraulic equipment (44B, 46B) on the second input / output port (64b) side when the first time (Ta) is greater than or equal to the first time threshold (T1a) and the second time (Tb) is less than the second time threshold (T1b).

[0147] By combining the results of the magnitude comparison between the two time periods and their respective thresholds in this way, the location of the abnormality can be identified, allowing for prompt action after recognizing abnormal signs and suppressing an increase in the downtime of the work machine (hydraulic excavator 1). Furthermore, in (4) above, the control device (50) may also determine that there are abnormal signs in the hydraulic motor (40) when the first time (Ta) is less than the first time threshold (T1a) and the second time (Tb) is less than the second time threshold (T1b). This allows the hydraulic motor (40) to also be identified as a location of abnormality.

[0148] (5) In any one of the above (1) to (4), preferably the control device (50) corrects the first time (Ta) based on the temperature of the pressurized oil in the first input / output port (64a).

[0149] As the temperature increases, the fluidity of the pressurized oil increases, and therefore the amount of leakage tends to increase. However, by correcting the first time (Ta) based on the temperature of the pressurized oil in this way, the accuracy of anomaly diagnosis can be improved.

[0150] Furthermore, it is preferable to make a correction such that the first time (Ta) becomes shorter in accordance with the rise in the temperature of the pressurized oil. It is also preferable to determine the correction amount based on whether the actual temperature of the pressurized oil is relatively higher or lower than the reference temperature, using the pressurized oil temperature at the time thresholds T1a, T2a, etc., related to the first time (Ta) as a reference. Alternatively, instead of correcting the first time, the time thresholds (T1a, T2a, etc.) related to the first time may be corrected according to the temperature.

[0151] (6) In any one of the above (1) to (5), preferably, the diagnostic start command is output by an operator's input to an input device (52) mounted on the work machine (hydraulic excavator 1).

[0152] This allows the operator to start the diagnosis by operating the input device (52) at the desired timing.

[0153] (7) In any one of the above (1) to (6), preferably, the control device (50) determines that when the first time (Ta) is less than the first time threshold (T1a), the greater the deviation between the first time (Ta) and the first time threshold (T1a), the higher the likelihood that there is an abnormality in the hydraulic motor (40) than in the hydraulic equipment (44A, 46A) on the first input / output port (64a) side.

[0154] (8) A fault diagnosis system for a hydraulic motor (40) and related hydraulic equipment (44A, 44B, 46A, 46B) mounted on a work machine (hydraulic excavator 1) comprises a directional control valve (30) having a first switching position that supplies pressurized oil to the first input / output port (64a) of the two input / output ports (64a, 64b) of the hydraulic motor (40), and a neutral position that shuts off the supply of pressurized oil to the two input / output ports (64a, 64b) and also shuts off the discharge of the pressurized oil supplied to the two input / output ports (64a, 64b) to the tank; a brake device (48) that brakes the hydraulic motor (40) when the directional control valve (30) is switched to the neutral position; a first pressure sensor (47A) that detects the pressure of the pressurized oil supplied to the first input / output port (64a); and a control device (50) that controls the directional control valve (30). When the directional control valve (30) is switched to the first switching position, the supply of pressurized oil to the first input / output port (64a) is started, and the first pressure sensor 47A detects that the pressure (Pa) at the first input / output port (64a) has reached a fifth value (P3a), the control device (50) is switched to the neutral position, thereby cutting off the supply of pressurized oil from the hydraulic pump (40) to the first input / output port (64a), and the rotation of the hydraulic motor (40) is locked by the brake device (48). The control device (50) calculates the first time (Ta) that has elapsed from the time the supply of pressurized oil is cut off until the pressure sensor 47A detects that the pressure at the first input / output port (64a) has decreased to a sixth value (P4a), and detects signs of abnormality in the hydraulic motor (40) and its related hydraulic equipment (44A, 46A) based on the first time (Ta).

[0155] When the processor of the controller 50 performs this process, if the conditions necessary for measuring the first time Ta are met, the processor automatically measures the first time Ta. Based on the measured first time Ta, it is possible to automatically determine whether or not there are signs of abnormality. This eliminates the need to interrupt work to perform a diagnosis, thereby suppressing a decrease in work efficiency, and also enables maintenance of the hydraulic motor and related equipment even if the diagnostic start operation is forgotten.

[0156] It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications that do not depart from the spirit of the invention. For example, the present invention is not limited to having all the configurations described in the embodiments described above, but also includes configurations in which some of those configurations are omitted. Furthermore, it is possible to add or replace a part of the configuration of one embodiment with a configuration of another embodiment.

[0157] Furthermore, some or all of the configurations related to the controller 50, as well as the functions and execution processes of each of those configurations, may be implemented in hardware (for example, by designing the logic for executing each function using an integrated circuit). Also, the configurations related to the controller 50 may be expressed as a program (software) that is read and executed by a processor (for example, a CPU) to realize each of the functions related to the controller 50's configuration. Information related to such a program can be stored, for example, in semiconductor memory (flash memory, SSD, etc.), magnetic storage devices (hard disk drives, etc.), and recording media (magnetic disks, optical disks, etc.).

[0158] Furthermore, in the descriptions of each embodiment above, the control lines and information lines shown are those deemed necessary for the description of that embodiment, but this does not necessarily mean that all control lines and information lines related to the product are shown. In reality, it is safe to assume that almost all components are interconnected.

[0159] 1...Hydraulic excavator, 20...Hydraulic pump, 30...Directional control valve, 31...Spool, 32A...Solenoid valve, 32B...Solenoid valve, 34A...Spool operating unit, 34B...Spool operating unit, 40...Hydraulic motor, 41A...Pipeline, 41B...Pipeline, 44A...Overload relief valve, 44B...Overload relief valve, 46A...Check valve, 46B...Check valve, 47A...Pressure sensor (first pressure sensor), 47B...Pressure sensor (second pressure sensor), 48...Brake device, 50...Controller (control device), 51...Operating lever, 51s...Slewing operation lever, 52...Input device, 53...Display, 64a...First input / output port (first intake / exhaust port), 64b...Second input / output port (second intake / exhaust port), 6 4c...Seal surface, 69c...Seal surface, 81...Diagnostic operation command unit, 82...Brake control unit, 83...Directional control valve control unit, 84...Pressure data acquisition unit, 85...Time calculation unit, 86...Determination unit, 87...Notification unit, 88...Mode determination unit, 89...Swivel operation detection unit, 90...Motor stop determination unit, 95...Mode selection switch, 96...Rotation speed sensor, 101...Traveling body, 102...Swiveling body, 103...Working device, P1a...First threshold (first value), P1b...Third threshold (third value), P2a...Second threshold (second value), P2b...Fourth threshold (fourth value), P3a...Fifth threshold, P4a...Sixth threshold, Pa...Pressure, T1a...Threshold (first time threshold), T1b...Threshold (second time threshold), Ta...First time, Tb...Second time

Claims

1. A fault diagnosis system for a hydraulic motor and related hydraulic equipment mounted on a work machine, comprising: a brake device for braking the hydraulic motor; a directional control valve having a first switching position for supplying pressurized oil to a first input / output port of the two input / output ports of the hydraulic motor, and a neutral position for shutting off the supply of pressurized oil to the two input / output ports and shutting off the discharge of the pressurized oil supplied to the two input / output ports to a tank; a first pressure sensor for detecting the pressure of the pressurized oil supplied to the first input / output port; and a control device for controlling the directional control valve, wherein when a diagnosis start command is input, the control device outputs a brake command to the brake device to lock the rotation of the hydraulic motor, outputs a switching signal to the directional control valve, and switches the directional control valve to the first switching position so that pressurized oil is supplied to the first input / output port. A fault diagnosis system characterized in that, when the first pressure sensor detects that the pressure at the first input / output port has reached a first value, a signal is output to the directional control valve to switch the directional control valve to the neutral position, thereby cutting off the supply of pressurized oil to the first input / output port; a first time is calculated from the time the supply of pressurized oil is cut off until the pressure at the first input / output port drops to a second value; and abnormal signs of the hydraulic motor and its related hydraulic equipment are detected based on the first time.

2. A fault diagnosis system according to claim 1, characterized in that the control device determines that there is an abnormality in at least one of the hydraulic motor and the hydraulic equipment on the first input / output port side when the first time is less than a first time threshold.

3. In the fault diagnosis system of claim 1, the directional control valve has a second switching position for supplying pressurized oil to the second input / output port of the two input / output ports, and further comprises a second pressure sensor for detecting the pressure of the pressurized oil supplied to the second input / output port, the control device, after calculating the first time, outputs a switching signal to the directional control valve and switches the directional control valve to the second switching position so that pressurized oil is supplied to the second input / output port, when the second pressure sensor detects that the pressure at the second input / output port has reached a third value, outputs a signal to the directional control valve to switch the directional control valve to the neutral position to shut off the supply of pressurized oil to the second input / output port, calculates the second time taken from the start of the shutdown of the supply of pressurized oil until the pressure at the second input / output port decreases to a fourth value, A fault diagnosis system characterized in that, when at least one of the following conditions is met—that the first time is less than a first time threshold and that the second time is less than a second time threshold—it is determined that there is an abnormality in one of the hydraulic motor, the hydraulic equipment on the first input / output port side, and the hydraulic equipment on the second input / output port side.

4. A fault diagnosis system according to claim 3, wherein the control device determines that there is an abnormality in the hydraulic motor when the first time is less than the first time threshold and the second time is less than the second time threshold; determines that there is an abnormality in the hydraulic equipment on the first input / output port side when the first time is less than the first time threshold and the second time is equal to or greater than the second time threshold; and determines that there is an abnormality in the hydraulic equipment on the second input / output port side when the first time is equal to or greater than the first time threshold and the second time is less than the second time threshold.

5. A fault diagnosis system according to claim 1, wherein the control device corrects the first time based on the temperature of the pressurized oil in the first input / output port.

6. A fault diagnosis system according to claim 1, characterized in that the diagnosis start command is output by an operator's input to an input device mounted on the work machine.

7. A fault diagnosis system according to claim 1, wherein the control device determines that when the first time is less than the first time threshold, the greater the deviation between the first time and the first time threshold, the higher the likelihood that the hydraulic motor is showing signs of abnormality than the hydraulic equipment on the first input / output port side.

8. A fault diagnosis system for a hydraulic motor and related hydraulic equipment mounted on a work machine, comprising: a directional control valve having a first switching position for supplying pressurized oil to a first input / output port among the two input / output ports of the hydraulic motor, and a neutral position for shutting off the supply of pressurized oil to the two input / output ports and preventing the pressurized oil supplied to the two input / output ports from being discharged into a tank; a brake device for braking the hydraulic motor when the directional control valve is switched to the neutral position; a first pressure sensor for detecting the pressure of the pressurized oil supplied to the first input / output port; and a control device for controlling the directional control valve, wherein the control device, when the directional control valve is switched to the first switching position, the supply of pressurized oil to the first input / output port is started, and the pressure at the first input / output port has been detected by the first pressure sensor to have reached a fifth value, the directional control valve is switched to the neutral position, thereby shutting off the supply of pressurized oil to the first input / output port and the rotation of the hydraulic motor is locked by the brake device, A fault diagnosis system characterized by calculating a first time elapsed from the time the supply of the pressurized oil is shut off until the time the first pressure sensor detects that the pressure at the first input / output port has decreased to a sixth value, and detecting signs of abnormality in the hydraulic motor and its related hydraulic equipment based on the first time.

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