JP2013160157A - Failure diagnosis apparatus for hydraulic pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnosis apparatus for a hydraulic pump, with which damage of a hydraulic pump sliding member can be detected accurately and surely while the hydraulic pump is operated.SOLUTION: A failure diagnosis apparatus for a hydraulic pump 1 includes: an inner pressure detection means 17 for detecting pressure within a casing; a tank pressure detection means 23 for detecting pressure in a tank 2 which supplies hydraulic oil to the hydraulic pump 1; and a failure diagnosis means including a storage section for storing a predetermined first reference pressure value, a first arithmetic section which calculates differential pressure by subtracting the pressure in the tank 2 detected by the tank pressure detection means 23 from the pressure in the casing detected by the inner pressure detection means 17, and a second arithmetic section which performs comparison operation between the differential pressure calculated by the first arithmetic section and the first reference pressure value and outputs a result of the operation.

Description

  The present invention relates to a failure diagnosis apparatus for a hydraulic pump.

  In order to make it possible to identify a failure site in the hydraulic pump with a simple configuration, the internal pressure grasping means for grasping the internal pressure of the housing member of the hydraulic pump and the discharge pressure of the hydraulic oil discharged from the oil chamber of the hydraulic pump are detected. There is a diagnostic apparatus for a hydraulic pump comprising a discharge pressure detecting means and a diagnostic means for diagnosing a wear state on a contact surface of the valve member of the hydraulic pump with a rotating member based on the internal pressure and the discharge pressure (for example, , See Patent Document 1).

JP 2007-77804 A

  The method of diagnosing the wear state of the hydraulic pump from the internal pressure and the discharge pressure of the conventional hydraulic pump described above is based on the discharge pressure determined in advance as a function of the detected internal pressure of the pump in the operating state above a certain discharge pressure. The wear state is diagnosed by comparing with the threshold value of the internal pressure of the pump. However, these threshold values are set based on the test results, and it is necessary to set them in consideration of the influence of the usage conditions and usage environment, so it is difficult to set these threshold values accurately. For this reason, it may be difficult to increase wear detection accuracy.

  By the way, in the case of a hydraulic system in a construction machine, a sealed oil tank is generally used. In such a hydraulic system, the flow rate of the hydraulic oil supplied from the oil tank to the hydraulic pump during operation of the hydraulic pump and the flow rate of the hydraulic oil returning to the oil tank are different every moment. The pressure may vary greatly. The oil pump sucks hydraulic oil from the oil tank and is connected to the oil tank by a drain pipe that discharges the drain inside the main body. For this reason, the internal pressure of the oil pump may be affected by the pressure fluctuation of the oil tank.

  For this reason, for example, in the hydraulic system including a sealed oil tank, the above-described conventional technique for determining the wear state of the hydraulic pump according to the internal pressure and the discharge pressure of the hydraulic pump without considering the pressure fluctuation of the oil tank In some cases, there was a possibility of misjudgment.

  The present invention has been made based on the above-described matters, and an object of the present invention is to provide a hydraulic pump failure diagnosis apparatus that can accurately and reliably detect damage to a hydraulic pump sliding member while the hydraulic pump is in operation. Is.

  In order to achieve the above object, a first invention provides a casing, a rotary shaft rotatably provided on the casing, and a plurality of cylinders provided so as to rotate integrally with the rotary shaft. A rotor provided in the cylinder, a plurality of pistons fitted in the cylinders of the rotor so as to be capable of reciprocating, and an intake intermittently communicating with the cylinders provided in the casing so as to be in sliding contact with the rotor An apparatus for diagnosing a hydraulic pump comprising a valve member having a port and a discharge port, comprising: an internal pressure detecting means for detecting a pressure in the casing; and a pressure of a tank for supplying hydraulic oil to the hydraulic pump. Tank pressure detecting means for detecting, a storage section for storing a first reference pressure value determined in advance, and the tank pressure detecting means from the pressure in the casing detected by the internal pressure detecting means. The tank pressure detected in step (1) is reduced, the first calculation unit that calculates the differential pressure is compared with the differential pressure calculated by the first calculation unit and the first reference pressure value, and the result is output. It is assumed that a failure diagnosis unit having a second calculation unit is provided.

  According to a second invention, in the first invention, a discharge pressure detecting means for detecting a discharge pressure of the hydraulic pump, a storage unit for storing a predetermined second reference pressure value, and the discharge pressure detecting means. The discharge pressure of the hydraulic pump detected in step 2 is compared with the second reference pressure value. When the discharge pressure of the hydraulic pump is less than the second reference pressure value, the first calculation unit and the second reference pressure value are compared. And a failure diagnosing means having a third calculation unit for outputting a signal for executing processing in the calculation unit.

  Furthermore, the third invention is characterized in that in the first or second invention, there is further provided a notifying means for notifying a failure diagnosis result of the hydraulic pump detected by the failure diagnosis means.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the tank is a sealed type, and the tank pressure detecting means detects the pressure of the gas phase part above the tank. Features.

  Furthermore, the fifth invention is the suction pressure detection means for detecting the suction pressure of the hydraulic pump in place of the tank pressure detection means in any one of the first to third inventions. It is provided with.

  According to the present invention, the failure diagnosis is performed based on the drain pressure of the hydraulic pump, the pressure of the oil tank, and the like while the hydraulic pump is in operation, so that the damage of the sliding member of the hydraulic pump can be detected accurately and reliably. Can do. As a result, countermeasures such as repair and replacement of parts can be executed in advance, so that downtime associated with repair or the like can be reduced. As a result, the production efficiency of construction machinery is improved.

1 is a longitudinal sectional view of a hydraulic pump to which a first embodiment of a failure diagnosis apparatus for a hydraulic pump according to the present invention is applied. It is a block diagram which shows the structure of 1st Embodiment of the failure diagnosis apparatus of the hydraulic pump of this invention. It is a characteristic figure showing the relation between pump internal pressure and oil tank pressure in a 1st embodiment of a failure diagnosis device of a hydraulic pump of the present invention. It is a flowchart figure which shows the processing content of 1st Embodiment of the failure diagnosis apparatus of the hydraulic pump of this invention. It is a block diagram which shows the structure of 2nd Embodiment of the failure diagnosis apparatus of the hydraulic pump of this invention. It is a flowchart figure which shows the processing content of 2nd Embodiment of the failure diagnosis apparatus of the hydraulic pump of this invention.

  DESCRIPTION OF EMBODIMENTS Embodiments of a hydraulic pump failure diagnosis apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a hydraulic pump to which a first embodiment of a failure diagnosis apparatus for a hydraulic pump according to the present invention is applied. FIG. 2 is a view of a first embodiment of a failure diagnosis apparatus for a hydraulic pump according to the present invention. FIG. 3 is a characteristic diagram showing the relationship between the pump internal pressure and the oil tank pressure in the first embodiment of the hydraulic pump failure diagnosis apparatus of the present invention, and FIG. 4 is a characteristic diagram showing the structure of the hydraulic pump of the present invention. It is a flowchart figure which shows the processing content of 1st Embodiment of a failure diagnosis apparatus.

  A hydraulic pump 1 shown in FIG. 1 is a variable displacement swash plate type hydraulic pump, and is used in a construction machine such as a hydraulic excavator and is driven to rotate by a prime mover or the like. The hydraulic pump 1 generally includes a casing 3, a rotating shaft 8, a cylinder block 9, a piston 11, a shoe 12, a swash plate 13, and a valve plate 15 as a valve member.

  The casing 3 includes a casing body 4 and a lid body 5 formed in a bottomed cylindrical shape, and the lid body 5 forms a drain oil chamber 6 between the casing body 4. The casing body 4 is provided with a drain port 4 </ b> A, and the drain port 4 </ b> A is connected to the hermetic oil tank 2 via a drain line 7.

  The rotating shaft 8 is rotatably provided on the casing 3. The cylinder block 9 is splined to the outer peripheral side of the rotary shaft 8 and rotates integrally with the rotary shaft 8 within the cylindrical portion of the casing body 4. The cylinder block 9 has one end side end face opposed to a swash plate 13 described later, and the other end end face slidably contacted with a valve plate 15 described later.

  A plurality of cylinders 10 are provided in the cylinder block 9. The cylinders 10 are spaced apart from each other with a certain interval in the circumferential direction of the cylinder block 9 around the rotation shaft 8, and are arranged in parallel with the axial direction of the cylinder block 9. The front end side of each cylinder 10 is open to one end side end surface of the cylinder block 9. On the base end side of each cylinder 10, a cylinder port 10A communicating with a later-described suction port 15A or discharge port 15B is formed.

  The piston 11 is slidably inserted into each cylinder 10. These pistons 11 reciprocate in the cylinder 10 as the cylinder block 9 rotates, and at this time, the working oil is sucked into the cylinder 10 from the suction passage 16A side, which will be described later, via the cylinder port 10A. The oil is discharged to the discharge passage 16B side described later as high-pressure oil. A shoe 12 is swingably attached to the projecting end side of each piston 11 projecting from each cylinder 10. These shoes 12 are in sliding contact with the swash plate 13 so as to draw a circular orbit.

  Here, a minute gap (not shown) is formed between the cylinder 10 and the piston 11 in order to improve the sliding characteristics of the piston 11. Part of the pressure oil in the cylinder 10 leaks into the drain oil chamber 6 of the casing 3 through this minute gap. The leaked oil causes the drain oil chamber 6 in the casing 3 to be almost filled with the hydraulic oil, and the hydraulic oil overflowing from the drain oil chamber 6 is returned to the sealed oil tank 2 via the drain line 7. It is.

  The swash plate 13 is tiltably supported by a swash plate support member 14 on the lid 5 side in the casing 3. The surface side of the swash plate 13 is a smooth surface with which the shoe 12 is in sliding contact. The shoe 12 is in sliding contact with the smooth surface of the swash plate 13 so as to draw a circular orbit. As a result, the piston 11 is reciprocated along the sliding surface of the cylinder 10. Further, a pair of leg portions 13A (only one is shown) formed of a convex curved surface is formed on the back surface side of the swash plate 13, and a pair of leg portions 13A corresponding to these leg portions 13A is formed on the surface side of the swash plate support member 14. A concave curved portion 14A (only one is shown) is formed.

  The valve plate 15 as a valve member is fixedly provided on the bottom side of the casing body 4 so as to be in sliding contact with the end face on the other end side of the cylinder block 9. The valve plate 15 is formed with a pair of suction port 15A and discharge port 15B having an arc shape. The suction port 15A and the discharge port 15B are intermittently communicated with each cylinder 10 in the cylinder block 9 via the cylinder port 10A, and the working oil in the tank 2 is sucked into the cylinder 10 from the suction passage 16A side. High pressure oil is discharged toward the external hydraulic actuator from the discharge passage 16B side.

  The suction passage 16 </ b> A and the discharge passage 16 </ b> B are formed at the bottom of the casing body 4. The suction passage 16A is connected to the oil tank 2 via a suction pipe 18 (see FIG. 2), and the discharge passage 16B is connected to a discharge pipe 19 (see FIG. 2) for supplying high-pressure oil toward the hydraulic actuator. Has been.

  The pressure sensor 17 as an internal pressure detecting means of the casing 3 is provided in the drain line 7 connecting the drain port 4A and the sealed oil tank 2. The pressure sensor 17 detects the pressure in the drain oil chamber 6 equal to the pressure in the drain line 7 (drain pressure) as the internal pressure of the casing 3, and outputs the detection signal to a signal processing device 21 (failure diagnosis means) described later. doing.

  FIG. 2 shows the configuration of the first embodiment of the hydraulic pump failure diagnosis apparatus of the present invention. In FIG. 2, the same reference numerals as those shown in FIG. In FIG. 2, the suction passage 16 </ b> A and the drain port 4 </ b> A of the hydraulic pump 1 are connected to the sealed oil tank 2 via a suction pipe 18 and a drain pipe 7, respectively. The discharge passage 16B of the hydraulic pump 1 is connected to one end side of a discharge pipe 19, and the other end side of the discharge pipe 19 is connected to a control valve 20 that distributes pressure oil from the hydraulic pump 1 to a hydraulic actuator such as a boom cylinder (not shown). It is connected. Further, one end of a return pipe 22 is connected to the oil tank 2, and the other end of the return pipe 22 is connected to a discharge port of a control valve 20 that discharges return oil from each actuator.

  The drain line 7 is provided with a pressure sensor 17 for measuring the pressure (PD) of the hydraulic oil flowing out from the drain port 4A of the hydraulic pump 1, and constitutes an internal pressure detecting means. The discharge pipe 19 is provided with a pressure sensor 25 for measuring the pressure (Pa) of the pressure oil flowing out from the discharge passage 16B of the hydraulic pump 1, and constitutes a discharge pressure detecting means. In addition, a pressure sensor 23 for measuring the pressure (PT) of the gas phase portion of the oil tank 2 is provided in the upper part of the oil tank 2 and constitutes a tank pressure detecting means. Further, the output signals of the pressure sensors 17, 25, 23 are input to the signal processing device 21. The signal processing device 21 takes in the detected value from the storage unit that stores the first reference pressure value and the pressure sensors 17 and 23, and the difference between the pressure in the casing 3 and the pressure in the gas phase in the oil tank 2. And a second calculation unit that compares and calculates the differential pressure calculated by the first calculation unit and the first reference pressure value stored in the storage unit. To determine the wear state of the hydraulic pump 1. Further, the signal processing device 21 outputs a signal representing the diagnostic contents to a notification device 24 such as a driver's cab monitor.

Next, the operation of the first embodiment of the hydraulic pump failure diagnosis apparatus of the present invention will be described with reference to FIGS.
First, the outline of the pressure of the internal hydraulic oil in the hydraulic pump 1 will be described. In FIG. 1, when the hydraulic pump 1 is driven by a prime mover or the like, the cylinder block 9 is rotationally driven in the casing 3 to reciprocate the piston 11 in the cylinder 10. At this time, a part of the pressure oil generated in the cylinder 10 leaks into the drain oil chamber 6 of the casing 3 through a minute gap between the cylinder 10 and the piston 11. Further, if the sliding resistance between the piston 11 and the cylinder 10 increases for some reason in the intake stroke of the piston 11, a detachment force is generated in the direction in which the cylinder block 9 is separated from the valve plate 15. Due to this detachment force, a gap is formed on the sliding contact surface between the cylinder block 9 and the valve plate 15, and the pressure oil leaks into the drain oil chamber 6. Such leaked oil is normally discharged to the tank 2 side through the drain pipe line 7 while being temporarily stored in the drain oil chamber 6.

  However, when wear, galling or the like occurs between the cylinder 10 and the piston 11 and the amount of leaked oil suddenly increases, a large amount of pressurized oil flows into the drain line 7. A throttling resistance is generated in the middle of the flow path, and the drain pressure (PD), which is the internal pressure of the casing 3, rapidly increases. Therefore, by measuring the pressure (drain pressure) of the hydraulic oil flowing out from the drain port 4A of the hydraulic pump 1 and comparing it with a predetermined threshold value, a failure diagnosis of the hydraulic pump 1 can be performed.

  However, as described above, the internal pressure of the casing 3 of the hydraulic pump 1 may be subject to fluctuations in the pressure of the oil tank 2, so that the failure of the hydraulic pump 1 can be accurately and reliably detected while the hydraulic pump 1 is operating. In order to do this, it is necessary to consider the pressure fluctuation of the oil tank 2.

  In the relational characteristic between the pump internal pressure and the oil tank pressure in the first embodiment of the hydraulic pump failure diagnosis apparatus of the present invention shown in FIG. 3, the characteristic line a is the drain line 7 detected by the pressure sensor 17. Of the oil tank 2 detected by the pressure sensor 23 (tank pressure PT), and the characteristic line c indicates the pressure difference between the drain pressure and the tank pressure. (PΔ) is shown respectively.

  The tank pressure (PT) of the characteristic line b shown in FIG. 3 greatly fluctuates. This is because the hydraulic oil supplied from the oil tank 2 to the hydraulic pump 1 during the operation of the hydraulic pump 1 and the oil tank. This is because the flow rate of the hydraulic oil that returns to 2 differs from moment to moment. On the other hand, the drain pressure (PD) of the characteristic line a changes so as to follow the fluctuation cycle of the tank pressure (PT) of the characteristic line b. This is because the drain port 4 </ b> A of the hydraulic pump 1 is connected to the oil tank 2 via the drain line 7. Therefore, in order to eliminate the influence of the tank pressure (PT) on the drain pressure (PD), when the differential pressure (PΔ) between the drain pressure and the tank pressure is examined, the behavior of the differential pressure (PΔ) on the characteristic line c is a peak. When the pressure is removed, the fluctuation range becomes smaller. By performing a failure diagnosis of the hydraulic pump 1 based on this differential pressure (PΔ), a failure in the operating state of the hydraulic pump 1 can be detected accurately and reliably.

  In the present embodiment, the failure diagnosis device for the hydraulic pump is configured such that the pressure of the hydraulic oil (drain pressure) flowing out from the drain port 4A of the hydraulic pump 1 and the pressure of the gas phase portion of the oil tank 2 measured by the pressure sensors 17 and 23. Based on (tank pressure), the signal processing device 21 performs arithmetic processing to detect a failure of the hydraulic pump 1.

  Next, processing contents of the signal processing device 21 will be described with reference to FIG.

  First, the signal processing device 21 measures the discharge pressure of the hydraulic pump 1 (step S100). Specifically, the pressure Pa of the pressure oil flowing out from the discharge passage 16B of the hydraulic pump 1 detected by the pressure sensor 25 is taken.

  The signal processing device 21 determines whether or not the discharge pressure Pa of the hydraulic pump 1 from the pressure sensor 25 is equal to or higher than a set pressure Pa0 corresponding to the pump discharge pressure during the relief operation (step S101). When the discharge pressure Pa of the hydraulic pump reaches a value corresponding to the relief operation, the behavior of the drain pressure (PD) does not follow the behavior of the tank pressure (PT). Therefore, the failure diagnosis is executed when the pressure is less than the set pressure Pa0. . If the discharge pressure Pa of the hydraulic pump 1 is equal to or higher than the set pressure Pa0, the process proceeds to return, and the calculation is restarted from the start. Otherwise, the process proceeds to (Step S102).

  The signal processing device 21 measures the drain pressure (PD) and the tank pressure (PT) (step S102). Specifically, the pressure of the hydraulic oil flowing out from the drain port 4A of the hydraulic pump 1 detected by the pressure sensor 17 and the pressure of the gas phase portion of the oil tank 2 detected by the pressure sensor 23 are taken in.

  The signal processing device 21 calculates a differential pressure (PΔ) between the drain pressure (PD) and the tank pressure (PT) (step S103). Specifically, in the signal processing device 21, the pressure difference (PΔ) is calculated by subtracting the value of the pressure in the gas phase portion of the oil tank 2 from the value of the pressure of the hydraulic oil flowing out from the drain port 4A of the hydraulic pump 1. doing.

  The signal processing device 21 determines whether or not the differential pressure (PΔ) calculated in step S103 is equal to or higher than a predetermined reference differential pressure (P0) (step S104). Here, the reference differential pressure P0 is determined on the basis of the differential pressure during normal operation of the hydraulic pump 1, but differs depending on the specifications of the hydraulic pump 1 and the configuration of the hydraulic circuit. Determined from test results. If the differential pressure (PΔ) is greater than or equal to the reference differential pressure (P0), the process proceeds to (Step S105), otherwise the process proceeds to (Step S106).

  The signal processing device 21 diagnoses the hydraulic pump 1 as a failure (step S105). Specifically, the signal processing device 21 determines that there is an abnormality in the sliding member of the hydraulic pump 1 and outputs a wear state abnormality signal to the notification device 24. For example, the notification device 24 notifies the operator that the wear state of the hydraulic pump 1 is abnormal. The signal processing device 21 proceeds to return and starts the calculation from the start again.

  On the other hand, when the differential pressure (PΔ) is less than the reference differential pressure (P0) in (Step S104), the signal processing device 21 diagnoses the hydraulic pump 1 as normal (Step S106). Specifically, the signal processing device 21 determines that the sliding member of the hydraulic pump 1 is normal, and outputs a wear state normal signal to the notification device 24. For example, the notification device 24 notifies the operator that the wear state of the hydraulic pump 1 is normal. The signal processing device 21 proceeds to return and starts the calculation from the start again.

  According to the first embodiment of the hydraulic pump failure diagnosis apparatus of the present invention described above, the drain pressure (PD) of the hydraulic pump 1, the pressure (PT) of the oil tank 2, etc., while the hydraulic pump 1 is operating. Therefore, it is possible to detect the damage of the sliding member of the hydraulic pump 1 accurately and reliably. As a result, countermeasures such as repair and replacement of parts can be executed in advance, so that downtime associated with repair or the like can be reduced. As a result, the production efficiency of construction machinery is improved.

  A second embodiment of the hydraulic pump failure diagnosis apparatus of the present invention will be described below with reference to the drawings. FIG. 5 is a system configuration diagram showing the configuration of the second embodiment of the hydraulic pump failure diagnosis apparatus of the present invention, and FIG. 6 shows the processing contents of the second embodiment of the hydraulic pump failure diagnosis apparatus of the present invention. FIG. 5 and 6, the same reference numerals as those shown in FIG. 1 to FIG. 4 are the same parts, and detailed description thereof is omitted.

  In the present embodiment, a pressure sensor 27 for measuring the suction pressure (PS) of the hydraulic pump 1 is provided instead of the pressure sensor 23 for measuring the pressure (PT) of the gas phase portion of the oil tank 2. This point is different from the first embodiment described above.

  In FIG. 5, the suction pipe 18 is provided with a pressure sensor 27 for measuring the suction pressure (PS) of the hydraulic pump 1, which is the pressure (suction pressure) of the hydraulic oil flowing into the suction passage 16A of the hydraulic pump 1. The output signal of the pressure sensor 27 is input to the signal processing device 21. The signal processing device 21 takes in the storage unit that stores the second reference pressure value and the detection values from the pressure sensors 17 and 27 and calculates the difference between the pressure in the casing 3 and the suction pressure of the hydraulic pump 1. 1 calculation unit, and a second calculation unit that compares and calculates the differential pressure calculated by the first calculation unit and the second reference pressure value stored in the storage unit, and performs calculation processing to be described later The wear state of the hydraulic pump 1 is determined. Further, the signal processing device 21 outputs a signal representing the diagnostic contents to a notification device 24 such as a driver's cab monitor.

  When the oil tank 2 is a closed type, the flow rate of hydraulic oil supplied from the oil tank 2 to the hydraulic pump 1 and the oil tank 2 are returned to the oil tank 2 during the operation of the hydraulic pump 1 as in the first embodiment described above. When the oil level in the oil tank 2 rises due to the difference in the flow rate of the coming hydraulic oil, the volume of the gas phase part of the oil tank 2 decreases, so the tank pressure (PT ) Will rise. At this time, since the hydraulic oil in the oil tank 2 is pressed by the air in the gas phase, the suction pressure (PS) of the hydraulic pump 1 also increases. Conversely, when the oil level in the oil tank 2 drops, the volume of the gas phase portion of the oil tank 2 increases, so that the tank pressure (PT) drops. At this time, since the pressure from the gas phase portion received by the hydraulic oil in the oil tank 2 decreases, the suction pressure (PS) of the hydraulic pump 1 also decreases.

  As described above, when the oil tank 2 is a sealed type, it has been found from experimental results that the suction pressure (PS) of the hydraulic pump 1 exhibits the same behavior as the tank pressure (PT). Therefore, in order to eliminate the influence of the tank pressure (PT) on the drain pressure (PD) in the first embodiment, based on the differential pressure (PΔ1) between the drain pressure and the suction pressure (PS), By performing the failure diagnosis, it is possible to accurately and reliably detect a failure in the operating state of the hydraulic pump 1.

  In the present embodiment, the failure diagnosis device for the hydraulic pump 1 uses the pressure of the hydraulic oil (drain pressure) flowing out from the drain port 4A of the hydraulic pump 1 measured by the pressure sensors 17 and 27 and the suction passage 16A of the hydraulic pump 1. A failure of the hydraulic pump 1 is detected by performing arithmetic processing in the signal processing device 21 based on the pressure (suction pressure) of the flowing hydraulic oil.

  Next, processing contents of the signal processing device 21 will be described with reference to FIG.

  First, the signal processing device 21 measures the discharge pressure of the hydraulic pump 1 (step S200). Specifically, the pressure Pa of the pressure oil flowing out from the discharge passage 16B of the hydraulic pump 1 detected by the pressure sensor 25 is taken.

  The signal processing device 21 determines whether or not the discharge pressure Pa of the hydraulic pump 1 from the pressure sensor 25 is equal to or higher than the set pressure Pa0 corresponding to the pump discharge pressure during the relief operation (step S201). When the discharge pressure Pa of the hydraulic pump reaches a level corresponding to the relief operation, the behavior of the drain pressure (PD) does not follow the behavior of the suction pressure (PS), so a failure diagnosis is executed when the pressure is less than the set pressure Pa0. . If the discharge pressure Pa of the hydraulic pump 1 is equal to or higher than the set pressure Pa0, the process proceeds to return, and the calculation is restarted from the start. Otherwise, the process proceeds to (Step S202).

  The signal processing device 21 measures the drain pressure (PD) and the suction pressure (PS) (step S202). Specifically, the pressure of the hydraulic oil flowing out from the drain port 4A of the hydraulic pump 1 detected by the pressure sensor 17 and the pressure of the hydraulic oil flowing into the suction passage 16A of the hydraulic pump 1 detected by the pressure sensor 27 are taken. Include.

  The signal processing device 21 calculates a differential pressure (PΔ1) between the drain pressure (PD) and the suction pressure (PS) (step S203). Specifically, in the signal processing device 21, the pressure difference of the hydraulic oil flowing into the suction passage 16 </ b> A of the hydraulic pump 1 is subtracted from the pressure value of the hydraulic oil flowing out of the drain port 4 </ b> A of the hydraulic pump 1. (PΔ1) is calculated.

  The signal processing device 21 determines whether or not the differential pressure (PΔ1) calculated in step S203 is equal to or higher than a predetermined reference differential pressure (P1) (step S204). Here, the reference differential pressure P1 is determined based on the differential pressure during normal operation of the hydraulic pump 1, but differs depending on the specifications of the hydraulic pump 1 and the configuration of the hydraulic circuit. Determined from test results. If the differential pressure (PΔ1) is greater than or equal to the reference differential pressure (P1), the process proceeds to (Step S205), and otherwise the process proceeds to (Step S206).

  The signal processing device 21 diagnoses the hydraulic pump 1 as a failure (step S205). Specifically, the signal processing device 21 determines that there is an abnormality in the sliding member of the hydraulic pump 1 and outputs a wear state abnormality signal to the notification device 24. For example, the notification device 24 notifies the operator that the wear state of the hydraulic pump 1 is abnormal. The signal processing device 21 proceeds to return and starts the calculation from the start again.

  On the other hand, if the differential pressure (PΔ1) is less than the reference differential pressure (P1) in (Step S204), the signal processing device 21 diagnoses the hydraulic pump 1 as normal (Step S206). Specifically, the signal processing device 21 determines that the sliding member of the hydraulic pump 1 is normal, and outputs a wear state normal signal to the notification device 24. For example, the notification device 24 notifies the operator that the wear state of the hydraulic pump 1 is normal. The signal processing device 21 proceeds to return and starts the calculation from the start again.

  According to the second embodiment of the hydraulic pump failure diagnosis apparatus of the present invention described above, the same effects as those of the first embodiment described above can be obtained.

DESCRIPTION OF SYMBOLS 1 Hydraulic pump 2 Oil tank 3 Casing 4 Casing main body 5 Cover body 6 Drain oil chamber 7 Drain pipe line 8 Rotating shaft 9 Cylinder block 10 Cylinder 11 Piston 12 Shoe 13 Swash plate 14 Swash plate support member 15 Valve plate (valve member)
15A Suction port 15B Discharge port 16A Suction passage 16B Discharge passage 17 Pressure sensor (internal pressure detection means)
18 Suction piping 19 Discharge piping 20 Control valve 21 Signal processing device 22 Return piping 23 Pressure sensor (tank pressure detection means)
24 Notification Device 25 Pressure Sensor (Discharge Pressure Detection Unit)
27 Pressure sensor (suction pressure detection means)

Claims (5)

A casing, a rotating shaft provided rotatably in the casing, a rotor provided with a plurality of cylinders and rotating integrally with the rotating shaft, and reciprocating in each cylinder of the rotor Hydraulic pressure comprising a plurality of pistons movably inserted and a valve member formed with suction ports and discharge ports intermittently communicating with the cylinders provided in the casing so as to be in sliding contact with the rotor. A fault diagnosis device for a pump,
An internal pressure detecting means for detecting the pressure in the casing;
Tank pressure detecting means for detecting a pressure of a tank for supplying hydraulic oil to the hydraulic pump;
A storage unit that stores a predetermined first reference pressure value, and a first pressure that calculates a differential pressure by subtracting the tank pressure detected by the tank pressure detecting means from the pressure in the casing detected by the internal pressure detecting means. A failure diagnosis means comprising: a calculation unit; and a second calculation unit that compares the differential pressure calculated by the first calculation unit with the first reference pressure value and outputs the result. A fault diagnosis device for hydraulic pumps. In the failure diagnosis device of the hydraulic pump according to claim 1,
A discharge pressure detecting means for detecting a discharge pressure of the hydraulic pump;
A storage unit for storing a predetermined second reference pressure value is compared with the discharge pressure of the hydraulic pump detected by the discharge pressure detecting means and the second reference pressure value. A failure diagnosing unit having a third calculation unit that outputs a signal for executing processing in the first calculation unit and the second calculation unit when the pressure is less than the second reference pressure value; A failure diagnosis device for a hydraulic pump. In the hydraulic pump failure diagnosis device according to claim 1 or 2,
A failure diagnosis apparatus for a hydraulic pump, further comprising notification means for notifying a failure diagnosis result of the hydraulic pump detected by the failure diagnosis means. In the hydraulic pump failure diagnosis device according to any one of claims 1 to 3,
The tank is of a sealed type, and the tank pressure detecting means detects the pressure in the gas phase portion above the tank. In the hydraulic pump failure diagnosis device according to any one of claims 1 to 3,
The hydraulic pump failure diagnosis apparatus according to claim 1, wherein the tank is of a sealed type, and includes a suction pressure detecting means for detecting a suction pressure of the hydraulic pump, instead of the tank pressure detecting means.

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