Hydraulic rotary machine system and swash plate type hydraulic rotary machine

Abstract

To accurately monitor the wear condition of shoes.SOLUTION: A swash plate type hydraulic pump 6 comprises a casing 7, a rotating shaft 11, a cylinder block 13 to be rotated integrally with the rotating shaft 11, a plurality of pistons 15 inserted and fitted into cylinders 14 of the cylinder block 13, a plurality of shoes 16 provided at tips of the plurality of pistons 15, and a swash plate 18 comprising a sliding surface 18D on which the plurality of shoes 16 slide. A monitoring device 31 comprises: a swash plate temperature sensor 32 attached to the swash plate 18 of the hydraulic pump 6, and detecting the temperature of the swash plate 18; and a monitoring part 36 for monitoring the wear condition of the shoes 16 on the basis of the temperature of the swash plate 18 detected by the swash plate temperature sensor 32. Thereby, the wear condition of the shoes 16 during the operation of the hydraulic pump 6 can be accurately monitored on the basis of the temperature of the swash plate 18 detected by the swash plate temperature sensor 32.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a hydraulic rotary machine system mounted as a hydraulic pump or a hydraulic motor on a construction machine such as a hydraulic excavator, and a swash plate type hydraulic rotary machine.

Background Art

[0002] Construction machines such as hydraulic excavators are equipped with a swash plate type hydraulic pump as a swash plate type hydraulic rotary machine. This swash plate type hydraulic pump includes a casing, a rotary shaft rotatably provided in the casing, a cylinder block having a plurality of cylinders and rotating integrally with the rotary shaft, a plurality of pistons reciprocally inserted into the cylinders of the cylinder block, a plurality of shoes respectively provided at the tips of the plurality of pistons, and a swash plate having a sliding surface on which the plurality of shoes slide.

[0003] When the rotary shaft is rotationally driven by a prime mover, the cylinder block rotates integrally with the rotary shaft. At this time, the plurality of shoes provided at the tips of the plurality of pistons slide on the sliding surface of the swash plate. As a result, the plurality of pistons repeat a suction stroke of sucking hydraulic oil into the cylinder while sliding and displacing from the top dead center to the bottom dead center in the cylinder, and a discharge stroke of discharging the hydraulic oil in the cylinder as high-pressure pressure oil while sliding and displacing from the bottom dead center to the top dead center.

[0004] During the operation of the hydraulic pump, the piston slides in the cylinder of the cylinder block, and the shoe slides on the sliding surface of the swash plate. These sliding parts wear with the operating time of the hydraulic pump, and eventually cause a failure of the hydraulic pump. In contrast, a failure diagnosis method is disclosed in which when the temperature difference between the oil temperature on the suction side and the oil temperature on the discharge side of the hydraulic pump becomes higher than a reference temperature difference, it is determined that the hydraulic pump has deteriorated over time (see Patent Document 1). Also, a failure diagnosis device is disclosed in which the temperature difference between the drain oils discharged from the plurality of hydraulic pumps is detected, and the detected temperature difference between the drain oils is compared with a reference temperature difference to determine that any one of the plurality of hydraulic pumps has failed (see Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, when the swash - plate type hydraulic pump is operating, the shoe attached to the tip of the piston slides on the sliding surface of the swash plate integrally with the cylinder block while being pressed against the sliding surface of the swash plate by the thrust of the piston. For this reason, many failures of the swash - plate type hydraulic pump are caused by wear of the shoe, and it is necessary to constantly monitor the wear state of the shoe and appropriately replace the parts.

[0007] However, in the failure diagnosis methods and failure diagnosis devices according to the above - described conventional technologies, since the failure diagnosis of the hydraulic pump is performed based on the temperature of the hydraulic oil or the drain oil, the detection accuracy of the wear state of the shoe related to the cause of the failure of the hydraulic pump is low. For this reason, there is a problem that it is difficult to extend the life of the hydraulic pump by appropriately replacing the worn shoe.

[0008] An object of the present invention is to provide a hydraulic rotary machine system and a swash - plate type hydraulic rotary machine that can accurately monitor the wear state of the shoe.

Means for Solving the Problems

[0009] One embodiment of the present invention is a hydraulic rotary machine system including a swash plate type hydraulic rotary machine and a monitoring device for monitoring the swash plate type hydraulic rotary machine. The swash plate type hydraulic rotary machine includes a casing, a rotary shaft rotatably provided in the casing, a cylinder block having a plurality of cylinders and rotating integrally with the rotary shaft, a plurality of pistons reciprocally inserted into the cylinders of the cylinder block, a plurality of shoes respectively provided at the tips of the plurality of pistons, and a swash plate having a sliding surface on which the plurality of shoes slide. The monitoring device includes a swash plate temperature sensor attached to the swash plate for detecting the temperature of the swash plate, and a monitoring unit for monitoring the wear state of the shoes based on the temperature of the swash plate detected by the swash plate temperature sensor.

Effect of the Invention

[0010] According to one embodiment of the present invention, the wear state of the shoes during the operation of the swash plate type hydraulic rotary machine can be accurately monitored based on the temperature of the swash plate directly detected by the swash plate temperature sensor. As a result, it is possible to appropriately replace the worn shoes and extend the life of the hydraulic rotary machine.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a case where a hydraulic rotary machine system according to an embodiment of the present invention is applied to a swash plate type hydraulic pump will be taken as an example, and it will be described in detail with reference to FIGS. 1 to 17.

[0013] Figs. 1 to 8 show a first embodiment of the present invention, and a hydraulic rotary machine system includes a hydraulic pump 6 and a monitoring device 31, which will be described later. A crawler-type hydraulic excavator 1, which is representative of construction machinery, includes a self-propelled crawler-type lower traveling body 2 and an upper swing body 3 rotatably mounted on the lower traveling body 2. A working device 4 is provided on the front side of the upper swing body 3, and the hydraulic excavator 1 performs earth and sand excavation work and the like by swinging the upper swing body 3 and pitching the working device 4.

[0014] The upper swing body 3 is equipped with an engine 5 as a prime mover, a hydraulic pump 6 driven by the engine 5, a monitoring device 31, and the like. The hydraulic pump 6 is constituted by a variable displacement swash plate type hydraulic pump shown in FIGS. 2 and 3, for example. The hydraulic pump 6 sucks in and pressurizes the hydraulic oil stored in a tank 10 described later, and supplies it to various hydraulic actuators such as a traveling hydraulic motor, a swing hydraulic motor, and a hydraulic cylinder mounted on the hydraulic excavator 1. The hydraulic pump 6 is constituted by a casing 7, a rotating shaft 11, a cylinder block 13, a piston 15, a shoe 16, a swash plate 18, and the like, which will be described later.

[0015] The casing 7 is constituted by a stepped cylindrical casing body 8 having one end side as a bottom 8A and a rear casing 9 attached to the casing body 8 so as to close the other end side of the casing body 8. The casing body 8 is provided with a drain port 8B for returning the hydraulic oil leaked into the casing 7 to the tank 10 and a cable port 8C for leading a cable 32A connected to a swash plate temperature sensor 32 described later to the outside of the casing 7.

[0016] As shown in Fig. 2, one end of the drain pipe 10A is connected to the drain port 8B, and the other end of the drain pipe 10A is connected to the tank 10. The cable port 8C is formed at a portion of the casing body 8 corresponding to the tilting center axis A of the inclined plate 18 described later, that is, at a portion of the casing body 8 that intersects the tilting center axis A. On the other hand, in the rear casing 9, supply / discharge passages 9A and 9B for supplying and discharging hydraulic oil (pressure oil) to / from various hydraulic actuators mounted on the hydraulic excavator 1 are formed.

[0017] The tank 10 is mounted on the upper swing body 3 and is connected to one of the supply / discharge passages 9A and 9B provided in the rear casing 9. In the tank 10, the hydraulic oil supplied to various hydraulic actuators mounted on the hydraulic excavator 1 is stored, and this hydraulic oil is supplied to a plurality of cylinders 14 described later when the hydraulic pump 6 operates. Also, the oil that leaks into the casing 7 when the hydraulic pump 6 operates flows back from the drain port 8B through the drain pipe 10A to the tank 10.

[0018] The rotating shaft 11 is rotatably provided in the casing 7. One side in the axial direction of the rotating shaft 11 is rotatably supported by the bottom 8A of the casing body 8 via a bearing 12A. One end 11A in the axial direction of the rotating shaft 11 protrudes outward from the bottom 8A of the casing body 8. The other end 11B in the axial direction of the rotating shaft 11 is rotatably supported by the rear casing 9 via a bearing 12B. Thus, the rotating shaft 11 rotates about its axis center with respect to the casing 7. For example, the engine 5 of the hydraulic excavator 1 is connected to one end 11A of the rotating shaft 11 via a power transmission mechanism (not shown) or the like, and the rotating shaft 11 is rotationally driven by this engine 5. A male spline portion 11C is provided at an intermediate portion in the axial direction of the rotating shaft 11.

[0019] The cylinder block 13 is located on the outer peripheral side of the rotating shaft 11 and is rotatably provided in the casing 7. A plurality of cylinders 14 are formed in the cylinder block 13. On one axial side (bottom 8A side) of the cylinder block 13, a cylindrical protrusion 13A protruding axially toward the swash plate 18 is integrally formed. On the outer peripheral side of the cylindrical protrusion 13A, a spherical guide 20 described later is inserted and fitted so as to be axially movable. The other axial side (rear casing 9 side) of the cylinder block 13 is a flat sliding surface 13B, and this sliding surface 13B is slidably in contact with a valve plate 22 described later.

[0020] An axial insertion hole 13C penetrating axially is provided in the central portion of the cylinder block 13, and the rotating shaft 11 is inserted through the axial insertion hole 13C. An internal spline portion 13D is formed on the inner peripheral surface of the axial insertion hole 13C on the side of the cylindrical protrusion 13A. The internal spline portion 13D is spline-coupled to the external spline portion 11C of the rotating shaft 11. Thereby, the cylinder block 13 rotates integrally with the rotating shaft 11.

[0021] The plurality of cylinders 14 are formed in the cylinder block 13. The cylinders 14 are spaced apart at regular intervals in the circumferential direction of the cylinder block 13 around the rotating shaft 11 and extend in the axial direction of the cylinder block 13. One end side of the plurality of cylinders 14 facing the valve plate 22 opens to the end surface on one axial side (cylindrical protrusion 13A side) of the cylinder block 13. On the other hand, cylinder ports 14A are respectively formed on the other end sides of the plurality of cylinders 14, and these cylinder ports 14A are intermittently communicated with and blocked from the supply / discharge passages 9A, 9B of the rear casing 9 via the supply / discharge ports 22A, 22B of the valve plate 22.

[0022] The plurality of pistons 15 are each slidably inserted into a plurality of cylinders 14 formed in the cylinder block 13. These pistons 15 reciprocate within their respective cylinders 14 by the rotation of the cylinder block 13, pressurize the hydraulic oil sucked into the cylinders 14, and discharge it as high-pressure hydraulic oil. The plurality of pistons 15 reciprocate between a bottom dead center where they protrude (extend) greatly from the cylinders 14 and a top dead center where they are reduced into the cylinders 14. That is, the plurality of pistons 15 slide-displace within the cylinders 14 from the top dead center to the bottom dead center while the cylinder block 13 rotates and the shoe 16 slides on the sliding surface 18D of the swash plate 18, sucking the hydraulic oil into the cylinders 14 during the intake stroke, and slide-displacing from the bottom dead center to the top dead center to discharge the hydraulic oil in the cylinders 14 as high-pressure hydraulic oil during the discharge stroke, repeating these processes.

[0023] The plurality of shoes 16 are swingably provided at the tips (protruding ends) of the pistons 15 protruding from the cylinders 14. The shoe 16 is pressed against the swash plate 18 by the pressing force (hydraulic pressure) from the piston 15 and rotates together with the rotary shaft 11, the cylinder block 13, and the piston 15 in this state. As a result, the plurality of shoes 16 slide on the swash plate 18 so as to draw an annular locus.

[0024] As shown in FIGS. 4 and 5, the shoe 16 includes a spherical piston attachment portion 16A attached to the tip of the piston 15 and a disk portion 16B integrally formed with the piston attachment portion 16A. The disk portion 16B has a swash plate sliding surface 16C that contacts a sliding surface 18D of the swash plate 18 described later, and an oil groove 16D for holding lubricating oil is provided in the swash plate sliding surface 16C between the sliding surface 16C and the sliding surface 18D of the swash plate 18. The lubricating oil held in the oil groove 16D serves as a hydrostatic bearing to lubricate between the swash plate sliding surface 16C of the shoe 16 and the sliding surface 18D of the swash plate 18. Therefore, when the oil groove 16D wears due to aging, the function of the hydrostatic bearing by the lubricating oil deteriorates, and the temperature of the swash plate 18 (sliding surface 18D) rises due to the frictional heat between the shoe 16 and the sliding surface 18D.

[0025] The cradle 17 is fixed to the bottom 8A of the casing main body 8 and supports the swash plate 18. The cradle 17 is provided with a pair of concave curved tilting sliding surfaces 17A that tiltably support the swash plate 18, and the pair of tilting sliding surfaces 17A are arranged opposite to each other with the rotation axis 11 interposed therebetween.

[0026] The swash plate 18 is tiltably provided in the casing 7. A shaft insertion hole 18A is formed in the central portion of the swash plate 18, and the rotation axis 11 is inserted through the shaft insertion hole 18A. The swash plate 18 is composed of a swash plate main body 18B supported by the bottom 8A of the casing main body 8 via the cradle 17 and a sliding plate 18C detachably (replaceably) attached to the swash plate main body 18B. The surface of the sliding plate 18C on the side opposite to the swash plate main body 18B is a sliding surface 18D on which a plurality of shoes 16 slide.

[0027] Here, the inclination angle of the swash plate 18 (sliding surface 18D) with respect to the piston 15 is changed by a swash plate tilting mechanism (not shown), and the stroke of the piston 15 changes according to the inclination angle of the swash plate 18, whereby the capacity of the hydraulic pump 6 changes. In this case, the swash plate 18 tilts about the tilting center axis A while being supported by the tilting sliding surface 17A of the cradle 17, and changes the inclination angle with respect to the piston 15.

[0028] Further, when the plurality of pistons 15 repeat the suction stroke and the discharge stroke due to the rotation of the cylinder block 13, a pressing force from the shoes 16 provided on the pistons 15 acts on the swash plate 18. In this case, the pressing force acting on the swash plate 18 from the shoes 16 when the plurality of pistons 15 are in the discharge stroke is greater than the pressing force acting on the swash plate 18 from the shoes 16 when the plurality of pistons 15 are in the suction stroke. Therefore, the sliding surface 18D of the swash plate 18 is divided into a high-pressure side portion 18D1 where the shoe 16 slides in the discharge stroke of the piston 15 and a low-pressure side portion 18D2 where the shoe 16 slides in the suction stroke of the piston 15, with the virtual line B (a straight line passing through the center of the swash plate 18 and perpendicular to the tilting center axis A) shown by the two-dot chain line in FIG. 6 interposed therebetween.

[0029] As shown in FIGS. 6 and 7, the swash plate 18 is provided with one swash plate groove 18E located between the swash plate body 18B and the sliding plate 18C. The swash plate groove 18E is formed on the surface of the sliding plate 18C opposite to the sliding surface 18D, and extends radially from the outer peripheral edge of the sliding plate 18C toward the center. That is, the swash plate groove 18E is provided at the contact portion between the swash plate body 18B and the sliding plate 18C, and is formed as a bottomed radial hole opening to the outer peripheral edge of the swash plate 18. The swash plate groove 18E is on the tilting center axis A of the swash plate 18 and is disposed at the high-pressure side portion 18D1 of the sliding surface 18D. A swash plate temperature sensor 32 is attached inside the swash plate groove 18E.

[0030] The retainer 19 is provided between the cylinder block 13 and the sliding plate 18C of the swash plate 18, and holds the plurality of shoes 16 slidably on the sliding surface 18D of the swash plate 18. The retainer 19 is formed as an annular plate body, and a spherical guide 20 is slidably fitted on the inner peripheral side of the retainer 19. The retainer 19 is formed with a plurality of shoe holding holes 19A at intervals in the circumferential direction, and the shoes 16 are respectively held in the plurality of shoe holding holes 19A. The retainer 19 presses the plurality of shoes 16 against the sliding surface 18D of the swash plate 18 by the spring force of a spring 21 described later via the spherical guide 20.

[0031] The spherical guide 20 is provided between the cylindrical protrusion 13A of the cylinder block 13 and the inner circumference of the retainer 19. The inner peripheral side of the spherical guide 20 is slidably inserted on the outer peripheral side of the cylindrical protrusion 13A, and the inner peripheral side of the retainer 19 is swingably (slidably) fitted on the spherical outer peripheral surface of the spherical guide 20. The inner peripheral side of the spherical guide 20 is spline-coupled to the male spline portion 11 of the rotating shaft 11 and rotates integrally with the rotating shaft 11.

[0032] The spring 21 is provided between the cylindrical protrusion 13A of the cylinder block 13 and the spherical guide 20. The spring 21 is configured, for example, by superposing a plurality of disc springs, and biases the cylinder block 13 and the spherical guide 20 in opposite directions with the spring 21 being inserted through the outer peripheral side of the rotary shaft 11. As a result, the sliding surface 13B of the cylinder block 13 is pressed against the valve plate 22, and the plurality of shoes 16 are pressed against the sliding surface 18D of the swash plate 18 via the spherical guide 20 and the retainer 19.

[0033] The valve plate 22 is fixed to the rear casing 9 and constitutes a switching valve plate that slidably contacts the sliding surface 13B of the cylinder block 13. A pair of supply / discharge ports 22A and 22B having an eyebrow shape arranged around the rotary shaft 11 are formed in the valve plate 22. One of the supply / discharge ports 22A and 22B serves as a discharge port on the high-pressure side, and the other port serves as a suction port on the low-pressure side. These pair of supply / discharge ports 22A and 22B intermittently communicate with the cylinder port 14A of the cylinder 14 as the cylinder block 13 rotates.

[0034] When the rotary shaft 11 of the hydraulic pump 6 rotates, the cylinder block 13 rotates integrally with the rotary shaft 11. At this time, the plurality of pistons 15 respectively provided in the plurality of cylinders 14 of the cylinder block 13 reciprocate within the cylinder 14 with a stroke amount corresponding to the tilt angle of the swash plate 18 as the shoes 16 attached to the tips thereof slide on the sliding surface 18D of the swash plate 18. As a result, the plurality of pistons 15 pressurize, for example, the hydraulic oil sucked into the cylinder 14 from the supply / discharge passage 9A side and discharge it as high-pressure hydraulic oil to the supply / discharge passage 9B side.

[0035] Next, a monitoring device 31 for the hydraulic pump 6 used in the present embodiment will be described.

[0036] The monitoring device 31 is provided on the upper swing body 3 of the hydraulic excavator 1 together with the hydraulic pump 6, and monitors the wear state of the shoe 16 that causes a failure of the hydraulic pump 6 based on the temperature of the swash plate 18. The monitoring device 31 includes a swash plate temperature sensor 32, an oil temperature sensor 35, a monitoring unit 36, and a transmitter 37, which will be described later.

[0037] The swash plate temperature sensor 32 is attached to the sliding plate 18C of the swash plate 18. The swash plate temperature sensor 32 is constituted by, for example, a K thermocouple, detects the temperature (plate temperature) of the sliding plate 18C of the swash plate 18 during the operation of the hydraulic pump 6, and outputs a signal corresponding to the detected temperature to the monitoring unit 36. As shown in FIGS. 6 and 7, the swash plate temperature sensor 32 is fixed (adhered) in a swash plate groove 18E provided in the sliding plate 18C of the swash plate 18 using a bonding material such as solder, and is further covered with a heat insulating material 33 such as a heat resistant adhesive and a heat resistant cement. A cable 32A connected to the swash plate temperature sensor 32 is led out to the outside of the casing 7 through a cable port 8C of the casing body 8 and is connected to the monitoring unit 36. The cable port 8C is sealed by a sealing plug 34.

[0038] In this case, the swash plate groove 18E of the swash plate 18 is arranged on the tilting center axis A of the swash plate 18, and the cable port 8C is formed at a portion of the casing body 8 that intersects the tilting center axis A. Therefore, the cable 32A of the swash plate temperature sensor 32 is led out to the outside of the casing 7 through the cable port 8C without being twisted by the tilting operation of the swash plate 18. On the other hand, the swash plate groove 18E of the swash plate 18 is arranged at the high-pressure side portion 18D1 of the sliding surface 18D. Therefore, when the plurality of pistons 15 are in the discharge stroke, the pressing force acting on the sliding surface 18D from the shoe 16 is large, and the frictional heat at the high-pressure side portion 18D1 where the frictional heat with the shoe 16 becomes larger can be accurately detected by the swash plate temperature sensor 32 attached in the swash plate groove 18E close to the sliding surface 18D.

[0039] The oil temperature sensor 35 is provided, for example, inside the tank 10. The oil temperature sensor 35 is constituted by, for example, a K thermocouple, detects the temperature of the hydraulic oil (operating oil temperature) stored in the tank 10 during the operation of the hydraulic pump 6, and outputs a signal corresponding to the detected temperature to the monitoring unit 36.

[0040] The monitoring unit 36 includes, for example, an arithmetic unit, a memory, an input unit for receiving signals, an output unit for transmitting signals (none of which are shown in the figure), etc., all of which are composed of a microcomputer. The input unit of the monitoring unit 36 is connected to the swash plate temperature sensor 32, the oil temperature sensor 35, etc. On the other hand, a transmitter 37 is connected to the output unit of the monitoring unit 36. The memory of the monitoring unit 36 stores, for example, the processing program shown in FIG. 8, that is, a processing program for monitoring the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 and the temperature of the hydraulic oil in the tank 10, and outputting a determination as to whether there is an abnormality in the hydraulic pump 6 to the transmitter 37, etc.

[0041] The transmitter 37 is mounted on the upper swing body 3 together with the monitoring unit 36, for example. When a determination result as to whether there is an abnormality in the hydraulic pump 6 is output from the monitoring unit 36, the transmitter 37 transmits this determination result to an external management center or the like (not shown in the figure) by wireless communication. In addition, the transmitter 37 also transmits other information such as the wear state of the shoe 16 and the temperature of the swash plate 18 to the management center. Thus, based on the information transmitted to the management center, not only the repair and replacement of the hydraulic pump 6 but also the replacement of parts such as the shoe 16 and the swash plate 18 can be appropriately performed.

[0042] The hydraulic rotary machine system according to the present embodiment has the monitoring device 31 as described above. Hereinafter, the operation in which the monitoring device 31 monitors the wear state of the shoe 16 during the operation of the hydraulic pump 6 and determines whether there is an abnormality in the hydraulic pump 6 will be described with reference to FIG. 8.

[0043] First, when the engine 5 operates and the rotating shaft 11 of the hydraulic pump 6 rotates, the cylinder block 13 rotates. At this time, the plurality of pistons 15 reciprocate within the cylinder 14 of the cylinder block 13 with a stroke amount corresponding to the tilting angle of the swash plate 18 as the shoe 16 attached to the tip thereof slides on the sliding surface 18D of the swash plate 18. As a result, the plurality of pistons 15 pressurize, for example, the hydraulic oil sucked into the cylinder 14 from the supply / discharge passage 9A side and discharge it as high-pressure hydraulic oil to the supply / discharge passage 9B side. In this way, as the cylinder block 13 rotates, the plurality of pistons 15 slide and displace from the top dead center to the bottom dead center within the cylinder 14 in the suction stroke for sucking the hydraulic oil into the cylinder 14, and slide and displace from the bottom dead center to the top dead center to discharge the hydraulic oil within the cylinder 14 as high-pressure hydraulic oil in the discharge stroke, repeating these processes.

[0044] During the operation of the hydraulic pump 6, the monitoring unit 36 constituting the monitoring device 31 executes a processing program (see FIG. 8) for monitoring the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 and the temperature of the hydraulic oil in the tank 10.

[0045] This processing program starts, for example, when the engine 5 is started. In step S1, a reference temperature difference T1 corresponding to the rotational speed of the engine 5 is set. The reference temperature difference T1 is the temperature difference between the temperature (plate temperature) Tp1 of the swash plate 18 and the temperature (hydraulic oil temperature) Tt1 of the hydraulic oil in the tank 10 when the hydraulic pump 6 is operating normally. This reference temperature difference T1 is set according to these three engine rotational speeds when the engine 5 operates at three levels of engine rotational speeds (energy-saving mode, normal mode, high-power mode).

[0046] In step S2, the plate temperature Tp1 detected by the swash plate temperature sensor 32 and the hydraulic oil temperature Tt1 in the tank 10 detected by the oil temperature sensor 35 are read. In the subsequent step S3, the temperature difference ΔT1 between the plate temperature Tp1 and the hydraulic oil temperature Tt1 is calculated, and the process proceeds to step S4.

[0047] In step S4, it is determined whether the temperature difference ΔT1 between the plate temperature Tp1 and the hydraulic oil temperature Tt1 is greater than the reference temperature difference T1 (T1 < ΔT1). If it is determined as "NO" in step S4, the temperature difference ΔT1 is smaller than the reference temperature difference T1, and the frictional heat generated between the shoe 16 and the swash plate 18 (sliding surface 18D) is low. Therefore, it is determined that the wear state of the shoe 16 (swash plate sliding surface 16C) is appropriate, and the process proceeds to step S5.

[0048] In step 5, a determination result that there is no abnormality in the hydraulic pump 6 is output to the transmitter 37. As a result, the transmitter 37 transmits the determination result that there is no abnormality in the hydraulic pump 6 to an external management center. Further, the transmitter 37 also transmits other information such as the wear state of the shoe 16 and the temperature of the swash plate 18 to the management center. Thereby, for example, the replacement timing of parts such as the shoe 16 and the swash plate 18 can be accurately grasped.

[0049] On the other hand, if it is determined as "YES" in step S4, the temperature difference ΔT1 is greater than the reference temperature difference T1, and the frictional heat generated between the shoe 16 and the swash plate 18 (sliding surface 18D) is high. Therefore, since it is determined that the wear state of the shoe 16 (swash plate sliding surface 16C) is progressing, the process proceeds to step S6.

[0050] In step S6, a determination result that an abnormality has occurred in the hydraulic pump 6 is output to the transmitter 37. As a result, the transmitter 37 transmits the determination result that an abnormality has occurred in the hydraulic pump 6 to an external management center. Thereby, for example, by sending an instruction to stop the hydraulic excavator 1 from the management center to the operator of the hydraulic excavator 1, it is possible to prevent the hydraulic pump 6 from being damaged.

[0051] In this way, the monitoring device 31 can directly detect the temperature of the swash plate 18 by the swash plate temperature sensor 32, and accurately detect the wear state of the shoe 16 during the operation of the hydraulic pump 6 based on the temperature difference between the temperature of the swash plate 18 and the temperature of the hydraulic oil in the tank 10. As a result, it is possible to quickly and accurately determine an abnormality of the hydraulic pump 6 due to wear of the shoe 16.

[0052] Here, the reason for determining the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 and the temperature of the hydraulic oil in the tank 10 will be described. First, the temperature of the swash plate 18 (plate temperature) rises with the increase in the temperature of the hydraulic oil in the tank 10 (hydraulic oil temperature) in addition to the frictional heat between the swash plate 18 and the shoe 16. Therefore, the plate temperature has a larger temperature rise width in an environment where the hydraulic oil temperature is high (such as when the hydraulic pump 6 is operating for a long time). For this reason, it is impossible to accurately detect the plate temperature due to the frictional heat between the swash plate 18 and the shoe 16, and it is difficult to accurately detect the wear state of the shoe 16 based only on the plate temperature.

[0053] On the other hand, when the wear state of the shoe 16 is appropriate, the temperature difference between the temperature of the hydraulic oil in the tank 10 (hydraulic oil temperature) and the temperature of the swash plate 18 (plate temperature) maintains a substantially constant value regardless of the change in the hydraulic oil temperature. Therefore, by monitoring the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 detected by the swash plate temperature sensor 32 and the temperature of the oil in the tank 10 detected by the oil temperature sensor 35, the wear state of the shoe 16 can be accurately detected even in an environment where the hydraulic oil temperature is high.

[0054] Thus, the hydraulic rotary machine system according to the present embodiment includes a swash plate type hydraulic pump 6 and a monitoring device 31. The hydraulic pump 6 includes a casing 7, a rotating shaft 11 rotatably provided in the casing 7, a cylinder block 13 having a plurality of cylinders 14 and rotating integrally with the rotating shaft 11, a plurality of pistons 15 reciprocally inserted into the cylinders 14 of the cylinder block 13, a plurality of shoes 16 respectively provided at the tips of the plurality of pistons 15, and a swash plate 18 having a sliding surface 18D on which the plurality of shoes 16 slide. The monitoring device 31 includes a swash plate temperature sensor 32 attached to the swash plate 18 for detecting the temperature of the swash plate 18, and a monitoring unit 36 for monitoring the wear state of the shoe 16 based on the temperature of the swash plate 18 detected by the swash plate temperature sensor 32.

[0055] According to this configuration, since the temperature of the swash plate 18 can be directly detected by the swash plate temperature sensor 32, the wear state of the shoe 16 during the operation of the hydraulic pump 6 can be accurately monitored based on the temperature of the swash plate 18. As a result, the abnormality of the hydraulic pump 6 associated with the wear of the shoe 16 can be determined early and accurately, so that parts such as the worn shoe 16 can be appropriately replaced, and the service life of the hydraulic pump 6 can be extended.

[0056] In the embodiment, the monitoring device 31 includes a transmitter 37 that transmits the wear state of the shoe 16 monitored by the monitoring unit 36 to the outside. According to this configuration, for example, based on the information from the monitoring unit 36 transmitted to an external management center, the aging changes of the hydraulic pump 6, the shoe 16, the swash plate 18, etc. can be monitored, and the replacement of these hydraulic pump 6, shoe 16, swash plate 18, etc. can be carried out at an appropriate timing.

[0057] In the embodiment, the swash plate 18 of the hydraulic pump 6 is configured such that the inclination angle with respect to the piston 15 is variable about the tilting center axis A. The swash plate temperature sensor 32 of the monitoring device 31 is attached to the swash plate 18 on the tilting center axis A. The monitoring device 31 is provided at a portion of the casing 7 corresponding to the tilting center axis A, and includes a cable port 8C that leads the cable 32A connecting between the swash plate temperature sensor 32 and the monitoring unit 36 to the outside of the casing 7. According to this configuration, the cable 32A of the swash plate temperature sensor 32 can be led to the outside of the casing 7 through the cable port 8C without being twisted by the tilting operation of the swash plate 18.

[0058] In the embodiment, the plurality of pistons 15 of the hydraulic pump 6 repeat a suction stroke of sucking hydraulic fluid into the cylinder 14 while the shoe 16 slides on the sliding surface 18D of the swash plate 18, and a discharge stroke of pressurizing and discharging the hydraulic fluid sucked into the cylinder 14. The swash plate temperature sensor 32 of the monitoring device 31 is provided at the high-pressure side portion 18D1 where the pressing force from the shoe 16 acts when the plurality of pistons 15 of the swash plate 18 are in the discharge stroke. According to this configuration, during the operation of the hydraulic pump 6, the frictional heat between the high-pressure side portion 18D1 of the swash plate 18 (sliding surface 18D) and the shoe 16 becomes larger. Therefore, the temperature of the swash plate 18 can be accurately detected by the swash plate temperature sensor 32 provided at this high-pressure side portion 18D1.

[0059] In the embodiment, the swash plate 18 of the hydraulic pump 6 is composed of a swash plate body 18B supported by the casing 7 and a sliding plate 18C attached to the swash plate body 18B and having a sliding surface 18D. A swash plate groove 18E is formed between the sliding plate 18C and the swash plate body 18B on the side opposite to the sliding surface 18D. The swash plate temperature sensor 32 of the monitoring device 31 is provided in the swash plate groove 18E. According to this configuration, the actual temperature of the sliding plate 18C on which the plurality of shoes 16 slide can be directly detected by the swash plate temperature sensor 32. Therefore, for example, the wear state of the shoe 16 can be accurately detected based on the frictional heat generated between the shoe 16 and the swash plate 18.

[0060] In the embodiment, the monitoring device 31 includes an oil temperature sensor 35 that detects the temperature of the hydraulic fluid stored in the tank 10 and supplied to the plurality of cylinders 14. The monitoring unit 36 monitors the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 detected by the swash plate temperature sensor 32 and the temperature of the hydraulic fluid in the tank 10 detected by the oil temperature sensor 35. According to this configuration, since the temperature difference between the temperature of the hydraulic oil in the tank 10 and the temperature of the swash plate 18 maintains a substantially constant value regardless of the change in the operating oil temperature, by monitoring the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 18 detected by the swash plate temperature sensor 32 and the temperature of the hydraulic fluid in the tank 10 detected by the oil temperature sensor 35, the wear state of the shoe 16 can be accurately determined even in an environment where the operating oil temperature is high.

[0061] Next, FIGS. 9 to 11 show a second embodiment of the present invention. The feature of this embodiment is that the monitoring device includes a plurality (for example, three) of swash plate temperature sensors. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0062] The hydraulic pump 41 used in the second embodiment is composed of a casing 7, a rotating shaft 11, a cylinder block 13, a piston 15, a shoe 16, etc., in the same manner as the hydraulic pump 6 according to the first embodiment. However, the configuration of the swash plate 42, which will be described later, is different from that of the swash plate 18 according to the first embodiment. Further, the monitoring device 43 used in the second embodiment is configured to include an oil temperature sensor 35, a monitoring unit 36, and a transmitter 37, in the same manner as the monitoring device 31 according to the first embodiment. However, the monitoring device 43 is different from the monitoring device 31 according to the first embodiment in that it includes three swash plate temperature sensors 44, 45, and 46.

[0063] The swash plate 42, like the swash plate 18 according to the first embodiment, changes the tilt angle with respect to the piston 15 by tilting about the tilt center axis A. The swash plate 42 is provided with a shaft insertion hole 42A at the center, and is composed of a swash plate body 42B supported by the casing body 8 and a sliding plate 42C detachably attached to the swash plate body 42B. The sliding plate 42C has a sliding surface 42D on which a plurality of shoes 16 slide. The sliding surface 42D is roughly divided into a high-pressure side portion 42D1 and a low-pressure side portion 42D2 with a virtual line B (a straight line passing through the center of the swash plate 42 and perpendicular to the tilt center axis A) shown by a two-dot chain line in FIG. 10 interposed therebetween.

[0064] On the swash plate 42, three swash plate grooves 42E, 42F, and 42G are provided between the swash plate body 42B and the sliding plate 42C. These three swash plate grooves 42E, 42F, and 42G are formed at intervals on the surface of the sliding plate 42C opposite to the sliding surface 42D. The swash plate groove 42E is arranged on the tilting center axis A of the swash plate 42, and the swash plate grooves 42F and 42G are arranged on both sides with the swash plate groove 42E in between. Also, the three swash plate grooves 42E, 42F, and 42G are arranged at the high-pressure side portion 42D1 of the sliding surface 42D.

[0065] The monitoring device 43 is composed of three swash plate temperature sensors 44, 45, 46, an oil temperature sensor 35, a monitoring unit 36, and a transmitter 37. The three swash plate temperature sensors 44, 45, and 46 respectively detect the temperature of the swash plate 42 and output a detection signal corresponding to the temperature to the monitoring unit 36. The swash plate temperature sensor 44 is provided in the swash plate groove 42E, the swash plate temperature sensor 45 is provided in the swash plate groove 42F, and the swash plate temperature sensor 46 is provided in the swash plate groove 42G, and each is covered by a heat insulating material 33.

[0066] The cables 44A, 45A, and 46A connected to the three swash plate temperature sensors 44, 45, and 46 are led out to the outside of the casing 7 through the cable port 8C of the casing body 8 in a state of being bundled using, for example, a bundling tool (not shown). The cables 44A, 45A, and 46A led out to the outside of the casing 7 are connected to the input side of the monitoring unit 36.

[0067] The hydraulic rotary machine system according to the second embodiment has the monitoring device 43 as described above. Hereinafter, the operation in which the monitoring device 43 monitors the wear state of the shoe 16 during the operation of the hydraulic pump 41 and determines whether there is an abnormality in the hydraulic pump 41 will be described with reference to FIG. 11.

[0068] FIG. 11 shows a processing program in which the monitoring unit 36 of the monitoring device 43 monitors the wear state of the shoe 16 based on the temperature difference between the temperature of the swash plate 42 detected by the three swash plate temperature sensors 44, 45, and 46 and the temperature of the hydraulic oil in the tank 10.

[0069] When the processing program shown in FIG. 11 starts, in step S11, three types of reference temperature differences T2, T3, and T4 corresponding to the rotational speed of the engine 5 are set. The reference temperature difference T2 is the temperature difference between the plate temperature Tp2 of the swash plate 42 detected by the swash plate temperature sensor 44 and the hydraulic oil temperature Tt2 when the hydraulic pump 6 is operating normally. The reference temperature difference T3 is the temperature difference between the plate temperature Tp3 of the swash plate 42 detected by the swash plate temperature sensor 45 and the hydraulic oil temperature Tt2 when the hydraulic pump 6 is operating normally. The reference temperature difference T4 is the temperature difference between the plate temperature Tp4 of the swash plate 42 detected by the swash plate temperature sensor 46 and the hydraulic oil temperature Tt2 when the hydraulic pump 6 is operating normally.

[0070] In step S12, the plate temperatures Tp2, Tp3, Tp4 detected by the swash plate temperature sensors 44, 45, 46 and the hydraulic oil temperature Tt2 detected by the oil temperature sensor 35 are read. In the subsequent step S13, the temperature difference ΔT2 between the plate temperature Tp2 and the hydraulic oil temperature Tt2, the temperature difference ΔT3 between the plate temperature Tp3 and the hydraulic oil temperature Tt2, and the temperature difference ΔT4 between the plate temperature Tp4 and the hydraulic oil temperature Tt2 are calculated, and the process proceeds to step S14.

[0071] In step S14, it is determined whether the temperature difference ΔT2 is greater than the reference temperature difference T2 (T2 < ΔT2), and the temperature difference ΔT3 is greater than the reference temperature difference T3 (T3 < ΔT3), and the temperature difference ΔT4 is greater than the reference temperature difference T4 (T4 < ΔT4). If it is determined as "NO" in step S14, at least one of the temperature differences ΔT2, ΔT3, ΔT4 between the plate temperatures Tp2, Tp3, Tp4 of the swash plate 42 detected by the three swash plate temperature sensors 44, 45, 46 and the hydraulic oil temperature Tt2 is smaller than the corresponding reference temperature differences T2, T3, T4. In this case, it is determined that the frictional heat generated between the shoe 16 and the swash plate 42 is low and the wear state of the shoe 16 is appropriate, and the process proceeds to step S15.

[0072] In step 15, a determination result that there is no abnormality in the hydraulic pump 41 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center. Also, the transmitter 37 transmits other information such as, for example, the wear state of the shoe 16 and the temperature of the swash plate 42 to the management center. Thereby, for example, the replacement timing of components such as the shoe 16 and the swash plate 42 can be accurately grasped.

[0073] Furthermore, when there is a plate temperature among the plate temperatures Tp2, Tp3, Tp4 whose temperature difference from the hydraulic oil temperature Tt2 exceeds the reference temperature difference, the transmitter 37 transmits the swash plate temperature sensor that detected this plate temperature exceeding the reference temperature difference to the management center. Thereby, the presence or absence of a failure of the swash plate temperature sensors 44, 45, 46 can be confirmed, and repairs, replacements, etc. for the failed swash plate temperature sensor can be promptly performed.

[0074] On the other hand, when it is determined "YES" in step S14, the temperature differences ΔT2, ΔT3, ΔT4 between the plate temperatures Tp2, Tp3, Tp4 of the swash plate 42 detected by the three swash plate temperature sensors 44, 45, 46 and the hydraulic oil temperature Tt2 are larger than the reference temperature differences T2, T3, T4. In this case, since it is determined that the frictional heat generated between the shoe 16 and the swash plate 42 is high and the wear state of the shoe 16 is progressing, the process proceeds to step S16. In step S16, a determination result that an abnormality has occurred in the hydraulic pump 41 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center.

[0075] The hydraulic rotation system according to the second embodiment has the monitoring device 43 as described above, and its basic operational effects are the same as those of the monitoring device 31 according to the first embodiment. However, the monitoring device 43 according to the present embodiment uses a plurality (for example, three) of swash plate temperature sensors 44, 45, 46, so that even if any of the swash plate temperature sensors 44, 45, 46 fails, the plate temperature of the swash plate 42 can be detected using the remaining normal swash plate temperature sensors, and the wear state of the shoe 16 can be continuously monitored.

[0076] Next, FIGS. 12 to 14 show a third embodiment of the present invention. The feature of this embodiment is that the inclined plate temperature sensors are provided at the high-pressure side portion and the low-pressure side portion of the sliding surface of the inclined plate, respectively. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0077] The hydraulic pump 51 used in the third embodiment is composed of a casing 7, a rotating shaft 11, a cylinder block 13, a piston 15, a shoe 16, etc., in the same manner as the hydraulic pump 6 according to the first embodiment. However, the configuration of the inclined plate 52 described later is different from that of the inclined plate 18 according to the first embodiment. Further, the monitoring device 53 used in the third embodiment does not include an oil temperature sensor, and is different from the monitoring device 31 according to the first embodiment in that it includes a high-pressure side inclined plate temperature sensor 54, a low-pressure side inclined plate temperature sensor 55, a monitoring unit 36, and a transmitter 37 described later.

[0078] The inclined plate 52 changes the inclination angle with respect to the piston 15 by tilting about the tilt center axis A. The inclined plate 52 is provided with a shaft insertion hole 52A at the center, and is composed of an inclined plate body 52B and a sliding plate 52C. The sliding plate 52C has a sliding surface 52D on which a plurality of shoes 16 slide. The sliding surface 52D is roughly divided into a high-pressure side portion 52D1 and a low-pressure side portion 52D2 with a virtual line B (a straight line passing through the center of the inclined plate 52 and perpendicular to the tilt center axis A) shown by a two-dot chain line in FIG. 13 interposed therebetween.

[0079] Two inclined plate grooves 52E and 52F are provided in the inclined plate 52 between the inclined plate body 52B and the sliding plate 52C. The two inclined plate grooves 52E and 52F are formed at intervals on the surface of the sliding plate 52C opposite to the sliding surface 52D. One inclined plate groove 52E is provided at the high-pressure side portion 52D1 of the sliding surface 52D, and the other inclined plate groove 52F is provided at the low-pressure side portion 52D2 of the sliding surface 52D. These two inclined plate grooves 52E and 52F are arranged on the tilt center axis A of the inclined plate 52.

[0080] The monitoring device 53 includes a high-pressure swashplate temperature sensor 54, a low-pressure swashplate temperature sensor 55, a monitoring unit 36, and a transmitter 37. The high-pressure swashplate temperature sensor 54 is provided in the swashplate groove 52E and outputs a detection signal corresponding to the temperature of the high-pressure side portion 52D1 of the swashplate 52 (sliding surface 52D) to the monitoring unit 36. The low-pressure swashplate temperature sensor 55 is provided in the swashplate groove 52F and outputs a detection signal corresponding to the temperature of the low-pressure side portion 52D2 of the swashplate 52 (sliding surface 52D) to the monitoring unit 36. Here, when the shoe 16 undergoes abnormal wear during the operation of the hydraulic pump 51, the frictional heat generated between the high-pressure side portion 52D1 of the swashplate 52 and the shoe 16 becomes higher than the frictional heat generated between the low-pressure side portion 52D2 of the swashplate 52 and the shoe 16, and the temperature difference between the two changes according to the wear state of the shoe 16.

[0081] The cable 54A connected to the high-pressure swashplate temperature sensor 54 and the cable 55A connected to the low-pressure swashplate temperature sensor 55 are led out to the outside of the casing 7 through the cable port 8C of the casing body 8 in a state of being bundled using, for example, a bundling tool (not shown). Then, the cables 54A and 55A led out to the outside of the casing 7 are connected to the input side of the monitoring unit 36.

[0082] The hydraulic rotary machine system according to the third embodiment has a monitoring device 53 as described above. Hereinafter, the operation in which the monitoring device 53 monitors the wear state of the shoe 16 during the operation of the hydraulic pump 51 and determines whether there is an abnormality in the hydraulic pump 51 will be described with reference to FIG. 14.

[0083] FIG. 14 shows a processing program in which the monitoring unit 36 of the monitoring device 53 monitors the wear state of the shoe 16 based on the temperature difference between the temperature of the high-pressure side portion 52D1 of the swashplate 52 detected by the high-pressure swashplate temperature sensor 54 and the temperature of the low-pressure side portion 52D2 of the swashplate 52 detected by the low-pressure swashplate temperature sensor 55.

[0084] When the processing program shown in FIG. 14 starts, in step S21, a reference temperature difference T5 corresponding to the rotational speed of the engine 5 is set. The reference temperature difference T5 is the temperature difference between the plate temperature Tp5 of the high-pressure side portion 52D1 of the swash plate 52 detected by the high-pressure side swash plate temperature sensor 54 and the plate temperature Tp6 of the low-pressure side portion 52D2 of the swash plate 52 detected by the low-pressure side swash plate temperature sensor 55 when the hydraulic pump 6 is operating normally.

[0085] In step S22, the plate temperature Tp5 detected by the high-pressure side swash plate temperature sensor 54 and the plate temperature Tp6 detected by the low-pressure side swash plate temperature sensor 55 are read. In the subsequent step S23, the temperature difference ΔT5 between the plate temperature Tp5 of the high-pressure side portion 52D1 and the plate temperature Tp6 of the low-pressure side portion 52D2 is calculated, and the process proceeds to step S24.

[0086] In step S24, it is determined whether the temperature difference ΔT5 is greater than the reference temperature difference T5 (T5 < ΔT5). If it is determined as "NO" in step S24, the temperature difference ΔT5 between the plate temperature Tp5 of the high-pressure side portion 52D1 of the swash plate 52 and the plate temperature Tp6 of the low-pressure side portion 52D2 of the swash plate 52 is smaller than the reference temperature difference T5. Therefore, it is determined that the frictional heat generated between the shoe 16 and the swash plate 52 is low and the wear state of the shoe 16 is appropriate, and the process proceeds to step S25.

[0087] In step S25, a determination result indicating that there is no abnormality in the hydraulic pump 51 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center. Also, the transmitter 37 transmits other information such as, for example, the wear state of the shoe 16 and the temperature of the swash plate 52 to the management center.

[0088] On the other hand, when it is determined as "YES" in step S24, the temperature difference ΔT5 between the plate temperature Tp5 of the high-pressure side portion 52D1 of the swash plate 52 and the plate temperature Tp6 of the low-pressure side portion 52D2 of the swash plate 52 is greater than the reference temperature difference T5. In this case, since the frictional heat generated between the shoe 16 and the swash plate 52 is high and it is determined that the wear state of the shoe 16 is progressing, the process proceeds to step S26. In step S26, a determination result that an abnormality has occurred in the hydraulic pump 51 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center.

[0089] The hydraulic rotary machine system according to the third embodiment has the monitoring device 53 as described above. Even when this monitoring device 53 is used, the same operational effects as those obtained when using the monitoring device 31 according to the first embodiment can be achieved.

[0090] Next, FIGS. 15 and 16 show a fourth embodiment of the present invention. The feature of this embodiment is that a swash plate temperature sensor is attached to each swash plate constituting a plurality of hydraulic pumps, and it is detected whether there is an abnormality in the hydraulic pump based on the temperature of the swash plate detected by these plurality of swash plate temperature sensors. In this embodiment, the same reference numerals are given to the same components as those in the first embodiment, and the description thereof is omitted.

[0091] In the fourth embodiment, when a hydraulic excavator is equipped with a plurality of hydraulic pumps, for example, first and second hydraulic pumps 61 and 62, a monitoring device 63 is provided for these first and second hydraulic pumps 61 and 62. The first hydraulic pump 61 and the second hydraulic pump 62 have the same structure and are composed of a casing 7, a rotating shaft 11, a cylinder block 13, a piston 15, a shoe 16, etc., similar to the hydraulic pump 6 according to the first embodiment.

[0092] The monitoring device 63 used in the fourth embodiment does not include an oil temperature sensor and is composed of a first swash plate temperature sensor 32' provided in the first hydraulic pump 61, a second swash plate temperature sensor 32" provided in the second hydraulic pump 62, a monitoring unit 36, and a transmitter 37.

[0093] The first swash plate temperature sensor 32' provided on the first hydraulic pump 61 detects the temperature of the swash plate 18 (sliding surface 18D) of the first hydraulic pump 61, and outputs a detection signal corresponding to this temperature to the monitoring unit 36. The second swash plate temperature sensor 32'' provided on the second hydraulic pump 62 detects the temperature of the swash plate 18 (sliding surface 18D) of the second hydraulic pump 62, and outputs a detection signal corresponding to this temperature to the monitoring unit 36. The monitoring unit 36 monitors the failures of the first and second hydraulic pumps 61 and 62 based on a comparison between the temperature of the swash plate 18 of the first hydraulic pump 61 detected by the first swash plate temperature sensor 32' and the temperature of the swash plate 18 of the second hydraulic pump 62 detected by the second swash plate temperature sensor 32''.

[0094] FIG. 16 shows a processing program in which the monitoring unit 36 of the monitoring device 63 monitors the wear state of the shoes 16 provided on the first and second hydraulic pumps 61 and 62 based on the temperature difference between the temperature of the swash plate 18 of the first hydraulic pump 61 detected by the first swash plate temperature sensor 32' and the temperature of the swash plate 18 of the second hydraulic pump 62 detected by the second swash plate temperature sensor 32''.

[0095] When the processing program shown in FIG. 16 starts, in step S31, a reference temperature difference T6 corresponding to the rotational speed of the engine 5 is set. The reference temperature difference T6 is the temperature difference between the plate temperature Tp7 of the swash plate 18 of the first hydraulic pump 61 detected by the first swash plate temperature sensor 32' and the plate temperature Tp8 of the swash plate 18 of the second hydraulic pump 62 detected by the second swash plate temperature sensor 32'' when the first hydraulic pump 61 is operating normally.

[0096] In step S32, the plate temperature Tp7 of the swash plate 18 of the first hydraulic pump 61 detected by the first swash plate temperature sensor 32' and the plate temperature Tp8 of the swash plate 18 of the second hydraulic pump 62 detected by the second swash plate temperature sensor 32'' are read. In the subsequent step S33, the temperature difference ΔT6 (ΔT6 = Tp7 - Tp8) between the plate temperature Tp7 and the plate temperature Tp8 is calculated, and the process proceeds to step S34.

[0097] In step S34, it is determined whether the absolute value |ΔT6| of the temperature difference ΔT6 is greater than the reference temperature difference T6 (|ΔT6|>T6). If it is determined as "NO" in step S34, the absolute value |ΔT6| of the temperature difference between the plate temperature Tp7 and the plate temperature Tp8 is smaller than the reference temperature difference T6. Therefore, it is determined that the wear states of the shoes 16 provided in the first hydraulic pump 61 and the wear states of the shoes 16 provided in the second hydraulic pump 62 are appropriate, and the process proceeds to step S35.

[0098] In step S35, a determination result that there is no abnormality in either the first or second hydraulic pumps 61, 62 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center. Also, the transmitter 37 transmits other information such as, for example, the wear states of the shoes 16 provided in the first and second hydraulic pumps 61, 62 and the temperature of the swash plate 18 to the management center.

[0099] On the other hand, if it is determined as "YES" in step S34, the absolute value |ΔT6| of the temperature difference ΔT6 is greater than the reference temperature difference T6. In this case, in order to determine which of the frictional heat generated between the swash plate 18 and the shoe 16 of the first hydraulic pump 61 and the frictional heat generated between the swash plate 18 and the shoe 16 of the second hydraulic pump 62 is at a higher temperature, the process proceeds to step S36. In step S36, it is determined whether the temperature difference ΔT6 is greater than 0 (zero) (ΔT6>0).

[0100] If it is determined as "NO" in step S36, the plate temperature Tp8 is higher than the plate temperature Tp7, and the frictional heat generated between the shoe 16 and the swash plate 18 provided in the second hydraulic pump 62 is high. Therefore, it is determined that the wear state of the shoe 16 of the second hydraulic pump 62 is progressing, and the process proceeds to step S37. In step S37, a determination result that an abnormality has occurred in the second hydraulic pump 62 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center.

[0101] On the other hand, if it is determined "YES" in step S36, the plate temperature Tp7 is higher than the plate temperature Tp8, and the frictional heat generated between the shoe 16 and the swash plate 18 provided in the first hydraulic pump 61 is high. Therefore, it is determined that the wear state of the shoe 16 of the first hydraulic pump 61 is progressing, and the process proceeds to step S38. In step S38, a determination result indicating that an abnormality has occurred in the first hydraulic pump 61 is output to the transmitter 37. The transmitter 37 transmits this determination result to an external management center.

[0102] The hydraulic rotary machine system according to the fourth embodiment includes the monitoring device 63 as described above. Even when a plurality of hydraulic pumps including the first and second hydraulic pumps 61 and 62 are mounted on a hydraulic excavator, the failures of the first and second hydraulic pumps 61 and 62 can be monitored using a single monitoring device 63.

[0103] Here, in the fourth embodiment, a case is exemplified in which the wear states of the shoes 16 of the two hydraulic pumps 61 and 62 are monitored based on the plate temperatures of the first and second hydraulic pumps 61 and 62 detected by the first and second swash plate temperature sensors 32' and 32". However, the present invention is not limited to this. For example, by using the processing program of the modification shown in FIG. 17, the wear states of the shoes 16 of three or more hydraulic pumps can be monitored.

[0104] FIG. 17 shows a processing program for monitoring the wear states of the shoes 16 of a plurality of hydraulic pumps based on the plate temperatures respectively detected by a plurality of swash plate temperature sensors attached to three or more (n) hydraulic pumps. Note that the processing program shown in FIG. 17 is premised on the fact that no abnormality occurs in two or more hydraulic pumps simultaneously.

[0105] When the processing program shown in FIG. 17 starts, in step S41, a reference temperature difference Ts corresponding to the rotational speed of the engine 5 is set. In step S42, the plate temperatures Tp1, Tp2, ···, Tpn of the first hydraulic pump, the second hydraulic pump, ···, the nth hydraulic pump respectively detected by the swash plate temperature sensors are read. In step S43, the maximum value TpMax of the plurality of read plate temperatures is extracted, and in step S44, the average value TpAve of the plate temperatures excluding the maximum value TpMax is calculated.

[0106] In step S45, it is determined whether the temperature difference between the maximum value TpMax and the average value TpAve of the plate temperatures is greater than the reference temperature difference Ts. If it is determined "NO" in step S45, for each of the plurality of hydraulic pumps, the frictional heat generated between the shoe 16 and the swash plate 18 is low, and the wear state of the shoe 16 is considered appropriate. Therefore, in step S46, a determination result indicating that none of the plurality of hydraulic pumps has an abnormality is output to the transmitter 37.

[0107] On the other hand, if it is determined "YES" in step S45, for the hydraulic pump with the plate temperature reaching the maximum value TpMax, it is considered that the frictional heat generated between the shoe 16 and the swash plate 18 is high and the wear state of the shoe 16 is progressing. Therefore, in step S47, a determination result indicating that there is an abnormality in the hydraulic pump with the plate temperature reaching the maximum value TpMax is output to the transmitter 37. Thus, for three or more hydraulic pumps, the wear state of the shoe 16 can be monitored based on the plate temperatures respectively detected by the swash plate temperature sensors.

[0108] In the first embodiment, the case where the determination result of whether there is an abnormality in the hydraulic pump 6 by the monitoring unit 36 is transmitted from the transmitter 37 to the management center is illustrated. However, the present invention is not limited to this, and the determination result by the monitoring unit 36 may be output to, for example, a monitor device or an alarm (both not shown) provided in the cab of the hydraulic excavator 1 to directly notify the operator.

[0109] In the third embodiment, an example is shown in which the cable 54A of the high-pressure-side swash plate temperature sensor 54 and the cable 55A of the low-pressure-side swash plate temperature sensor 55 are bundled using a bundling tool and led out to the outside of the casing 7 through the cable port 8C of the casing body 8. However, the present invention is not limited to this. For example, another cable port that intersects the tilting center axis A of the swash plate 18 may be provided on the side of the casing body 8 opposite to the cable port 8C, and the cable 55A of the low-pressure-side swash plate temperature sensor 55 may be led out to the outside of the casing 7 through the other cable port.

[0110] Furthermore, in the embodiment, a variable-capacity swash plate type hydraulic pump 6 is exemplified as the swash plate type hydraulic rotary machine. However, the present invention is not limited to this, and it can also be applied to, for example, a fixed-capacity swash plate type hydraulic pump or a swash plate type hydraulic motor.

Explanation of reference numerals

[0111] 1 Hydraulic excavator 2 Lower traveling body (vehicle body) 3 Upper revolving body (vehicle body) 4 Working device 6, 41, 51 Hydraulic pump 7 Casing 8C Cable port 10 Tank 11 Rotating shaft 13 Cylinder block 15 Piston 16 Shoe 18, 42, 52 Swash plate 18D, 42D, 52D Sliding surface 18D1, 42D1, 52D1 High-pressure side part 18D2, 42D2, 52D2 Low-pressure side part 18E, 42E, 42F, 42G, 52E, 52F Swash plate groove 31, 43, 53, 63 Monitoring device 32, 44, 45, 46 Swash plate temperature sensor 32′ First swash plate temperature sensor 32″ Second swash plate temperature sensor 32A, 44A, 45A, 46A, 54A, 55A cables 36 Monitoring unit 37 Transmitter 54 High-pressure side inclined plate temperature sensor 55 Low-pressure side inclined plate temperature sensor 61 First hydraulic pump 62 Second hydraulic pump

Claims

1. A hydraulic rotary machine system comprising an inclined plate type hydraulic rotary machine and a monitoring device for monitoring the inclined plate type hydraulic rotary machine, wherein the inclined plate type hydraulic rotary machine includes a casing, a rotary shaft rotatably provided in the casing, a cylinder block having a plurality of cylinders and rotating integrally with the rotary shaft, a plurality of pistons reciprocally inserted into the cylinders of the cylinder block, a plurality of shoes respectively provided at the tips of the plurality of pistons, and an inclined plate having a sliding surface on which the plurality of shoes slide, the monitoring device includes an inclined plate temperature sensor attached to the inclined plate for detecting the temperature of the inclined plate, and a monitoring unit for monitoring the wear state of the shoe based on the temperature of the inclined plate detected by the inclined plate temperature sensor. The hydraulic rotary machine system is characterized by this.

2. The hydraulic rotary machine system according to claim 1, wherein the monitoring device includes a transmitter for transmitting the wear state of the shoe monitored by the monitoring unit to the outside.

3. The inclined plate of the inclined plate type hydraulic rotary machine is configured such that the inclination angle with respect to the piston is variable about the tilting center axis, the inclined plate temperature sensor of the monitoring device is attached to the inclined plate on the tilting center axis, and the monitoring device is provided at a portion of the casing corresponding to the tilting center axis, and includes a cable port for leading a cable connecting between the inclined plate temperature sensor and the monitoring unit to the outside of the casing. The hydraulic rotary machine system according to claim 1 is characterized by this.

4. The plurality of pistons of the inclined plate type hydraulic rotary machine repeat an intake stroke of sucking hydraulic fluid into the cylinder while the shoe slides on the sliding surface of the inclined plate, and a discharge stroke of pressurizing and discharging the hydraulic fluid sucked into the cylinder, and the inclined plate temperature sensor of the monitoring device is provided at a high-pressure side portion of the inclined plate where the pressing force from the shoe acts when the plurality of pistons are in the discharge stroke. The hydraulic rotary machine system according to claim 1 is characterized by this.

5. The inclined plate of the inclined plate type hydraulic rotary machine is composed of an inclined plate body supported by the casing, and a sliding plate attached to the inclined plate body and having the sliding surface, and an inclined plate groove is formed between the sliding plate and the inclined plate body on the side opposite to the sliding surface. The hydraulic rotary machine system according to claim 1, wherein the swash plate temperature sensor of the monitoring device is provided in the swash plate groove.

6. The monitoring device includes an oil temperature sensor that detects the temperature of the oil stored in the tank and supplied to the plurality of cylinders. The monitoring unit monitors the wear state of the shoe based on the temperature difference between the temperature of the swash plate detected by the swash plate temperature sensor and the temperature of the oil in the tank detected by the oil temperature sensor. The hydraulic rotary machine system according to claim 1.

7. The hydraulic rotary machine system according to claim 1, wherein a plurality of the swash plate temperature sensors are provided on the swash plate.

8. The plurality of pistons of the swash plate type hydraulic rotary machine repeat an intake stroke of sucking oil into the cylinder while the shoe slides on the sliding surface of the swash plate, and a discharge stroke of pressurizing and discharging the oil sucked into the cylinder. The swash plate temperature sensor of the monitoring device includes a high-pressure side swash plate temperature sensor provided at a high-pressure side portion where the pressing force from the shoe acts when the plurality of pistons are in the discharge stroke among the swash plates. It consists of a low-pressure side swash plate temperature sensor provided at a low-pressure side portion where the pressing force from the shoe acts when the plurality of pistons are in the intake stroke among the swash plates. The monitoring unit of the monitoring device monitors the wear state of the shoe based on the temperature difference between the temperature detected by the high-pressure side swash plate temperature sensor and the temperature detected by the low-pressure side swash plate temperature sensor. The hydraulic rotary machine system according to claim 1.

9. In a swash plate type hydraulic rotary machine including a casing, a rotary shaft rotatably provided in the casing, a cylinder block having a plurality of cylinders and rotating integrally with the rotary shaft, a plurality of pistons reciprocally inserted into the cylinders of the cylinder block, a plurality of shoes respectively provided at the tips of the plurality of pistons, and a swash plate having a sliding surface on which the plurality of shoes slide. The swash plate type hydraulic rotary machine further includes a swash plate temperature sensor attached to the swash plate for detecting the temperature of the swash plate.

Images