Swashplate-type hydraulic rotary machine and swashplate-type hydraulic rotary machine system

Abstract

To improve ease of attachment of a sensor.SOLUTION: A hydraulic pump 1 comprises main bearings 21 and 22 and a subsidiary bearing 23 provided in a casing body 2, and rotatably supporting a rotating shaft 4. An insertion hole 29 is provided in the casing body 2, and extends toward the subsidiary bearing 23. A vibration sensor 30 is inserted from the insertion hole 29, and attached to the casing body 2. The vibration sensor 30 comprises a linear detection part 30C extending along an outer peripheral surface of the subsidiary bearing 23 while being in contact with the outer peripheral surface of the subsidiary bearing 23, and detecting vibration of the subsidiary bearing 23.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an inclined-axis hydraulic rotary machine and an inclined-axis hydraulic rotary machine system that are mounted on construction machines such as hydraulic excavators and hydraulic cranes and used as hydraulic pumps and hydraulic motors.

Background Art

[0002] Generally, an inclined-axis hydraulic rotary machine includes a plurality of bearings that rotatably support a rotary shaft. In order to grasp the maintenance timing of such bearings, a monitoring device for monitoring the state of the bearings is known (Patent Document 1). The monitoring device described in Patent Document 1 includes a load detection means for detecting a load acting on the bearing, and a determination means for making a predetermined determination regarding the bearing using the detection signal of the load detection means as one of the determination information.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, for example, in an inclined-axis hydraulic pump, a plurality of tapered roller bearings are used as bearings for the rotary shaft in order to support the hydraulic reaction force generated in the axial direction. At this time, the plurality of tapered roller bearings are attached in a state where the main bearing and the sub-bearing face each other. It is necessary to apply a preload to these bearings. If the preload is applied too high due to variations in management, the sub-bearing with a small load capacity will reach the end of its life first. Therefore, by monitoring the state of the sub-bearing during operation and detecting damage to the sub-bearing at an early stage, it may be possible to grasp damage to the pump itself.

[0005] In order to monitor the state of the sub-bearing and detect damage to the sub-bearing at an early stage, it is conceivable to apply the monitoring device described in Patent Document 1. However, in this monitoring device, as a load detection means, for example, a strain gauge sensor needs to be fixed in advance to the outer diameter portion of the bearing with an adhesive, and the bearing needs to be placed inside the casing. Further, since the sensor is adhesively fixed to the bearing, when replacing the sensor due to a sensor failure, it is necessary to temporarily remove the bearing from the casing and replace the sensor.

[0006] In this case, the attachment and replacement of the sensor to the bearing are performed with the bearing not inside the casing. For this reason, when inserting the bearing into the casing, there is a risk that the sensor cable may be cut or the sensor cable may be pinched between the casing and the bearing. Further, there is also a problem that it takes a long time when replacing the sensor.

[0007] An object of the present invention is to provide an inclined-axis hydraulic rotary machine and an inclined-axis hydraulic rotary machine system capable of improving the attachability of a sensor.

Means for Solving the Problems

[0008] The present invention relates to an inclined shaft type hydraulic rotary machine including a casing, a cylinder block rotatably provided in the casing and having a plurality of cylinder holes spaced apart in the circumferential direction and extending in the axial direction, a plurality of pistons reciprocally inserted into the respective cylinder holes of the cylinder block, a rotary shaft rotatably provided in the casing, extending in a direction inclined from the central axis of rotation of the cylinder block, connected to the plurality of pistons, and rotating together with the cylinder block, and a plurality of tapered roller bearings provided in the casing for rotatably supporting the rotary shaft. In the inclined shaft type hydraulic rotary machine, an insertion hole provided in the casing and extending toward a detected bearing formed of any one of the plurality of tapered roller bearings, and a vibration sensor inserted through the insertion hole and attached to the casing, having a linear detection portion that contacts the outer peripheral surface of the detected bearing, extends along the outer peripheral surface of the detected bearing, and detects vibration of the detected bearing are provided. , the plurality of tapered roller bearings include a main bearing and a sub-bearing facing each other, the bearing to be detected is the sub-bearing, the sub-bearing is attached to the casing with its outer ring fitted to a spacer and its inner ring in contact with a bearing nut, an annular flexible member is provided between the spacer and the vibration sensor, tightening of the bearing nut expands the outer diameter of the outer ring of the sub-bearing, and the detection part of the vibration sensor is sandwiched between the inner peripheral surface of the flexible member and the outer peripheral surface of the outer ring of the sub-bearing It is characterized by this.

[0009] Further, an inclined shaft type hydraulic rotary machine system according to the present invention includes a casing, a cylinder block rotatably provided in the casing and having a plurality of cylinder holes spaced apart in the circumferential direction and extending in the axial direction, a plurality of pistons reciprocally inserted into the respective cylinder holes of the cylinder block, a rotary shaft rotatably provided in the casing, extending in a direction inclined from the central axis of rotation of the cylinder block, connected to the plurality of pistons, and rotating together with the cylinder block, a plurality of tapered roller bearings provided in the casing for rotatably supporting the rotary shaft, an insertion hole provided in the casing and extending toward a detected bearing formed of any one of the plurality of tapered roller bearings, a vibration sensor inserted through the insertion hole and attached to the casing, having a linear detection portion that contacts the outer peripheral surface of the detected bearing, extends along the outer peripheral surface of the detected bearing, and detects vibration of the detected bearing, and a bearing monitoring device connected to the vibration sensor and monitoring the state of the detected bearing based on a vibration detection signal output from the vibration sensor. , the plurality of tapered roller bearings include a main bearing and a sub-bearing facing each other, the bearing to be detected is the sub-bearing, the sub-bearing is attached to the casing with its outer ring fitted to a spacer and its inner ring in contact with a bearing nut, an annular flexible member is provided between the spacer and the vibration sensor, tightening of the bearing nut expands the outer diameter of the outer ring of the sub-bearing, and the detection part of the vibration sensor is sandwiched between the inner peripheral surface of the flexible member and the outer peripheral surface of the outer ring of the sub-bearing It is characterized by the following.

Advantages of the Invention

[0010] According to the present invention, even when the detected bearing is inside the casing, a vibration sensor can be attached to the detected bearing. As a result, damage to the vibration sensor when installing the vibration sensor can be prevented, the vibration sensor can be easily replaced, and the attachability of the vibration sensor can be improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0012] Hereinafter, as a swashplate type hydraulic rotary machine and a swashplate type hydraulic rotary machine system according to an embodiment of the present invention, a variable displacement swashplate type hydraulic pump will be taken as an example and described in detail with reference to the accompanying drawings.

[0013] Figs. 1 to 7 show embodiments of the present invention. In Fig. 1, a variable displacement swashplate type hydraulic pump 1 (hereinafter referred to as the hydraulic pump 1) as a swashplate type hydraulic rotary machine is rotationally driven by, for example, a prime mover (an engine or an electric motor serving as a drive source) of a hydraulic excavator, sucks oil from an oil tank, and supplies pressurized oil to various hydraulic devices (none shown) connected to the downstream side of a hydraulic pipeline. The hydraulic pump 1 includes a casing body 2, a head casing 3, a rotating shaft 4, a cylinder block 5, a piston 7, main bearings 21 and 22, and a sub-bearing 23.

[0014] The casing body 2 is formed as a hollow cylindrical body serving as an outer shell of the hydraulic pump 1. The casing body 2 includes a bearing housing portion 2A formed in a substantially cylindrical shape and located on one side in the axial direction, and a cylinder block housing portion 2B extending obliquely from the other end of the bearing housing portion 2A. That is, one side in the axial direction of the casing body 2 is the bearing housing portion 2A. A head casing 3 is assembled to the other end of the cylinder block housing portion 2B. The casing body 2 and the head casing 3 constitute the casing of the entire hydraulic pump 1.

[0015] The head casing 3 is provided to close an opening on the other side in the axial direction of the casing body 2, that is, the other end of the cylinder block housing portion 2B. The head casing 3 is attached to a head side end face located on the cylinder block housing portion 2B side of the casing body 2. The head casing 3 has a concave arc-shaped sliding contact portion 3B serving as a rectangular long groove on one end face 3A located on the casing body 2 side. On the other hand, a cylinder hole 11 of a tilting mechanism 10 is provided in the head casing 3 at a position inside the concave arc-shaped sliding contact portion 3B.

[0016] The head casing 3 is formed with a pair of supply and discharge passages (both not shown). Among these supply and discharge passages, the low-pressure side supply and discharge passage (suction passage) supplies the hydraulic oil from a tank (not shown) into each cylinder hole 5B through a suction port (not shown) serving as a low-pressure port of the valve plate 8. Further, the high-pressure side supply and discharge passage (discharge passage) discharges (ejects) the pressurized oil (discharge oil) from the side of a discharge port (not shown) serving as a high-pressure port of the valve plate 8 toward a downstream hydraulic device (for example, a hydraulic actuator such as a hydraulic cylinder).

[0017] The rotating shaft 4 serving as the input shaft is located within the bearing housing portion 2A of the casing body 2 and is provided to extend axially within the bearing housing portion 2A. The rotating shaft 4 is rotatably supported by the bearing housing portion 2A of the casing body 2 via main bearings 21, 22 and a sub-bearing 23 which are a plurality (for example, three) of tapered roller bearings. One end side of the rotating shaft 4 becomes a protruding end 4A that protrudes axially from the casing body 2, and a prime mover such as an engine is connected to this protruding end 4A via a power transmission mechanism and the like (both not shown). On the other hand, a disk-shaped drive disk 4B is formed at the tip end portion on the insertion side into the casing body 2, that is, at the other end portion in the axial direction, of the rotating shaft 4. That is, the tip end portion of the rotating shaft 4 on the side opposite to the protruding end 4A in the axial direction is the drive disk 4B.

[0018] The drive disk 4B is provided with a central side concave spherical surface portion 4B1 located on the central side of the other end face facing the cylinder block 5. The spherical portion 6A of the center shaft 6 is slidably connected to the central side concave spherical surface portion 4B1. On the other end face of the drive disk 4B, a plurality of outer diameter side concave spherical surface portions 4B2 for rotational transmission are provided at intervals in the circumferential direction on the radially outer side of the central side concave spherical surface portion 4B1. The spherical portion 7A of each piston 7 is swingably connected to each outer diameter side concave spherical surface portion 4B2. The rotating shaft 4 is provided with a male screw portion 4C located between the protruding end 4A and the drive disk 4B. A bearing nut 25 is screwed onto the male screw portion 4C.

[0019] The cylinder block 5 is provided in the cylinder block housing portion 2B of the casing body 2. The cylinder block 5 is connected to the drive disk 4B via the center shaft 6, each piston 7, etc., and rotates integrally with the rotating shaft 4. The cylinder block 5 is formed as a cylindrical body (cylindrical tube), and a center shaft insertion hole 5A as a center cylinder is provided along its central axis. The center shaft 6 is inserted into the center shaft insertion hole 5A. Further, a plurality of cylinder holes 5B extending in the axial direction are arranged around the center shaft insertion hole 5A in the circumferential direction at intervals.

[0020] Furthermore, the other end face in the axial direction on the side of the valve plate 8 of the cylinder block 5 is a sliding contact end face 5C. The sliding contact end face 5C is formed in a concave spherical shape. The sliding contact end face 5C is in sliding contact with the sliding spherical surface portion 8B of the valve plate 8. That is, the cylinder block 5 has a concave spherical sliding contact end face 5C formed on the other end face in the axial direction. Between the sliding contact end face 5C of the cylinder block 5 and each cylinder hole 5B, a plurality of cylinder ports 5D (only one is shown) that communicate with and are blocked from the suction port and the discharge port (both not shown) of the valve plate 8 on the side of the sliding contact end face 5C are formed.

[0021] The center shaft 6 is inserted through the center shaft insertion hole 5A of the cylinder block 5 in order to center the cylinder block 5. One end side of the center shaft 6 is slidably connected to the rotation center position of the drive disk 4B of the rotating shaft 4. That is, one end side of the center shaft 6 is a spherical portion 6A. The spherical portion 6A is swingably (slidably) connected into the central side concave spherical surface portion 4B1 of the drive disk 4B. The other end side of the center shaft 6 is inserted through the center shaft insertion hole 5A.

[0022] The plurality of pistons 7 are reciprocally inserted into respective cylinder holes 5B of the cylinder block 5. One end side of the plurality of pistons 7 protruding from the cylinder holes 5B is swingably connected to the drive disk 4B of the rotating shaft 4. That is, one end side of each piston 7 is a spherical portion 7A. The spherical portion 7A is swingably (slidingly) connected into the outer diameter side concave spherical surface portion 4B2 of the drive disk 4B. Each piston 7 reciprocates within the cylinder hole 5B as the cylinder block 5 tilted with respect to the rotating shaft 4 rotates, and sucks (draws in) and discharges (ejects) the hydraulic fluid.

[0023] The valve plate 8 is provided between the head casing 3 and the cylinder block 5. The valve plate 8 tilts along the concave arc-shaped sliding contact portion 3B of the head casing 3. On one end face 8A of the valve plate 8, that is, on one end face 8A which becomes the end face (side face) on the side facing the cylinder block 5, a convex spherical sliding surface portion 8B that slidably contacts the sliding contact end face 5C of the cylinder block 5 is formed. The sliding spherical surface portion 8B of the valve plate 8 is in concave-convex fitting (spherical fitting) with the sliding contact end face 5C of the cylinder block 5. The sliding spherical surface portion 8B of the valve plate 8 serves as a switching surface on which the sliding contact end face 5C of the cylinder block 5 slides while rotating.

[0024] On the other hand, the other end face of the valve plate 8 on the side opposite to the sliding spherical surface portion 8B is a convex arc-shaped sliding contact portion 8C protruding with an arc corresponding to the concave arc-shaped sliding contact portion 3B of the head casing 3. The convex arc-shaped sliding contact portion 8C of the valve plate 8 is tiltably slidably contacted with the concave arc-shaped sliding contact portion 3B of the head casing 3 during the operation of the tilting mechanism 10.

[0025] Also, the valve plate 8 is provided with a fitting hole 8D penetrating axially at the center of the sliding spherical surface portion 8B. The tip side of the servo pin 13 is inserted into the fitting hole 8D. The valve plate 8 is formed with an inhalation port and an exhaust port (both not shown) having an eyebrow shape.

[0026] The intake port and the discharge port intermittently communicate with the cylinder port 5D of each cylinder hole 5B as the cylinder block 5 rotates. That is, as the cylinder block 5 rotates while its sliding contact end face 5C slides against the sliding spherical surface portion 8B of the valve plate 8, the supply or discharge of pressure oil is performed between each cylinder hole 5B and the intake port or the discharge port.

[0027] The tilting mechanism 10 is provided on the head casing 3. The tilting mechanism 10 tilts the valve plate 8 together with the cylinder block 5. The tilting mechanism 10 includes a cylinder hole 11 that is located deeper than the deepest part of the concave arc-shaped sliding contact portion 3B and extends linearly in the tilting direction of the valve plate 8, a servo piston 12 as an operating portion that is slidably inserted into the cylinder hole 11, and a servo pin 13 that is provided at an intermediate portion in the longitudinal direction of the servo piston 12, protrudes radially from the servo piston 12, and extends toward the valve plate 8 side.

[0028] The base end side of the servo pin 13 is inserted into a pin hole 12A formed in the servo piston 12, and the tip end side is inserted (connected) into a fitting hole 8D of the valve plate 8. The tilting mechanism 10 can move the servo piston 12 along the cylinder hole 11 by supplying hydraulic oil from an oil through hole (not shown) into the cylinder hole 11. In this way, by moving the servo piston 12, the valve plate 8 can be tilted together with the cylinder block 5 via the servo pin 13. Thereby, the tilting mechanism 10 can adjust the tilting angle of the cylinder block 5 and the valve plate 8 with respect to the rotating shaft 4 between the minimum tilting position and the maximum tilting position.

[0029] The main bearings 21 and 22 are provided in the casing body 2. As shown in FIGS. 1 and 2, the two main bearings 21 and 22 are mounted inside the bearing housing portion 2A of the casing body 2. The main bearings 21 and 22 are constituted by tapered roller bearings. In the main bearings 21 and 22, as going from the other side in the axial direction to one side, the rotation axis of the tapered roller is inclined from the outer diameter side toward the inner diameter side. The main bearing 21 includes an inner ring 21A, an outer ring 21B, and tapered rollers 21C. The main bearing 22 includes an inner ring 22A, an outer ring 22B, and tapered rollers 22C. The main bearing 21 is located on the other side in the axial direction than the main bearing 22 and is disposed at the inner part of the bearing housing portion 2A.

[0030] In addition, in the present embodiment, the case where the hydraulic pump 1 includes two main bearings 21 and 22 is exemplified. However, the present invention is not limited to this, and the hydraulic pump may include one main bearing or may include three or more main bearings.

[0031] The sub-bearing 23 is provided in the casing body 2. The sub-bearing 23 is mounted inside the bearing housing portion 2A of the casing body 2 via a spacer 24. The sub-bearing 23 faces the main bearing 22. The sub-bearing 23 includes an inner ring 23A, an outer ring 23B, and tapered rollers 23C. The tapered rollers 23C are rotatably held between the inner ring 23A and the outer ring 23B. In the sub-bearing 23, as going from the other side in the axial direction to one side, the rotation axis of the tapered roller is inclined from the inner diameter side toward the outer diameter side. The main bearings 21, 22 and the sub-bearing 23 rotatably support the rotating shaft 4. The sub-bearing 23 is a bearing to be detected and is the object of vibration detection. The sub-bearing 23 is formed to have a smaller outer diameter dimension than the main bearings 21 and 22 and is disposed at a position farther from the cylinder block 5 than the main bearings 21 and 22.

[0032] The spacer 24 is located radially outside the sub-bearing 23 and is disposed between the outer peripheral surface of the sub-bearing 23 (outer ring 23B) and the inner peripheral surface of the bearing housing portion 2A. As shown in FIGS. 2 to 5, the spacer 24 includes a main body portion 24A, a bottom portion 24B, and a protruding portion 24C. The main body portion 24A is formed in a cylindrical shape having a larger radial dimension than the outer ring 23B of the sub-bearing 23. The sub-bearing 23 is disposed within the main body portion 24A. The bottom portion 24B is located at the end on the other axial side of the main body portion 24A and is formed in a disk shape. The bottom portion 24B protrudes radially inward from the end on the other axial side of the main body portion 24A. One axial side surface of the bottom portion 24B abuts against the axial end surface on the other side of the outer ring 23B of the sub-bearing 23. The other axial side surface of the bottom portion 24B abuts against the axial end surface on one side of the outer ring 22B of the main bearing 22. The protruding portion 24C protrudes from the end surface on one axial side of the main body portion 24A and is formed in an arc shape. A plurality (for example, six) of the protruding portions 24C are attached in the circumferential direction of the main body portion 24A. These plurality of protruding portions 24C are spaced apart from each other in the circumferential direction of the main body portion 24A. Therefore, a gap is formed between two adjacent protruding portions 24C in the circumferential direction.

[0033] On the inner peripheral side of the main body portion 24A, a sensor housing portion 24D is formed at a position on one axial side. The sensor housing portion 24D is an annular groove extending over the entire circumference of the main body portion 24A and is formed on the inner peripheral surface of the main body portion 24A. The sensor housing portion 24D is located radially inside the main body portion 24A and the protruding portion 24C and is formed by notching these inner peripheral portions. The sensor housing portion 24D extends axially from the tip of the protruding portion 24C to a position facing the outer peripheral surface of the outer ring 23B of the sub-bearing 23.

[0034] The bearing nut 25 is screwed onto the male thread portion 4C of the rotating shaft 4. As shown in Fig. 2, the bearing nut 25 is formed in a cylindrical shape with a smaller radial dimension than the spacer 24, and is provided with an internal thread portion 25A that engages with the male thread portion 4C on its inner peripheral side. As shown in Figs. 4 and 5, the end face on the other axial side of the bearing nut 25 abuts against the end face on one axial side of the inner ring 23A of the sub-bearing 23. The bearing nut 25 applies a pressing force to the inner ring 23A from one axial side to the other. Due to this pressing force, a force acting from the radially inner side to the outer side is applied to the tapered roller 23C and the outer ring 23B of the sub-bearing 23.

[0035] The seal cover 26 covers one axial side of the sub-bearing 23 and is attached to the casing body 2. As shown in Fig. 2, the seal cover 26 is formed in a disc shape and is inserted inside the radial direction of the bearing housing portion 2A. The seal cover 26 covers the opening end side of the bearing housing portion 2A. An annular ring retainer 27 abuts against the end face on one axial side of the seal cover 26. The ring retainer 27 is attached to an annular groove on the inner peripheral surface of the bearing housing portion 2A. On the other hand, the tip end face of the protruding portion 24C of the spacer 24 abuts against the end face on the other axial side of the seal cover 26. At this time, the seal cover 26 is sandwiched between the spacer 24 and the ring retainer 27 in the axial direction. Thereby, the seal cover 26 is attached inside the bearing housing portion 2A in a retaining state.

[0036] An annular seal member 28 is attached inside the radial direction of the seal cover 26. The seal member 28 is in sliding contact with the outer peripheral surface of the rotating shaft 4 and seals between the inside and the outside of the bearing housing portion 2A.

[0037] The insertion hole 29 is provided in the casing main body 2. As shown in FIGS. 2 and 3, the insertion hole 29 is constituted by a through hole and extends from the outer peripheral surface of the casing main body 2 toward the sub-bearing 23 that becomes the bearing to be detected. Specifically, the insertion hole 29 extends linearly from the outer peripheral surface to the inner peripheral surface of the casing main body 2. For example, two insertion holes 29 are formed in the casing main body 2. In the present embodiment, these two insertion holes 29 extend parallel to each other. One end of the insertion hole 29 opens to the outside of the casing main body 2. As shown in FIG. 3, the other end of the insertion hole 29 opens into the bearing housing portion 2A of the casing main body 2 at a position facing the gap between the two protruding portions 24C of the spacer 24. Thereby, the insertion hole 29 communicates with the sensor housing portion 24D of the spacer 24 through the gap between the two protruding portions 24C.

[0038] The vibration sensor 30 is constituted by, for example, a piezo-electric wire sensor in which a piezo-film is wound around a core wire. The vibration sensor 30 is inserted from one insertion hole 29 and attached to the casing main body 2. Specifically, the proximal end side of the vibration sensor 30 reaches the outer peripheral surface of the outer ring 23B of the sub-bearing 23 through the gap between one insertion hole 29 and the two protruding portions 24C of the spacer 24. At this time, the proximal end side of the vibration sensor 30 reaches the outer peripheral surface of the outer ring 23B of the sub-bearing 23 through the gap between one insertion hole 29 and the two protruding portions 24C of the spacer 24.

[0039] The tip portion of the vibration sensor 30 is drawn out from the other insertion hole 29 to the outside of the casing main body 2. At this time, the distal end side of the vibration sensor 30 is drawn out to the outside of the casing main body 2 through the gap between the two protruding portions 24C of the spacer 24 and the other insertion hole 29 from the outer peripheral surface of the outer ring 23B of the sub-bearing 23.

[0040] The vibration sensor 30 extends along the outer peripheral surface of the sub-bearing 23 in a state of being in contact with the outer peripheral surface of the outer ring 23B of the sub-bearing 23. The vibration sensor 30 may be wound around the outer peripheral surface of the outer ring 23B a plurality of times or may be wound around approximately one turn.

[0041] As shown in FIG. 3, the vibration sensor 30 has a base-end-side fixing portion 30A, a tip-end-side fixing portion 30B, and a detection portion 30C. The base-end-side fixing portion 30A is located at the base-end portion of the vibration sensor 30 and protrudes from the inside of the casing body 2 to the outside through one insertion hole 29. The tip-end-side fixing portion 30B is located at the tip-end portion of the vibration sensor 30 and protrudes from the inside of the casing body 2 to the outside through the other insertion hole 29. The tip-end-side fixing portion 30B is slightly thicker than the detection portion 30C for noise countermeasures.

[0042] Both the base-end-side fixing portion 30A and the tip-end-side fixing portion 30B are fixed to the casing body 2 using a compression fitting 31. The compression fitting 31 is formed of, for example, a metal material and is attached to the outer peripheral surface of the casing body 2 in a state of being inserted into the insertion hole 29. The compression fitting 31 seals the insertion hole 29 and prevents the oil inside the casing body 2 from leaking through the insertion hole 29.

[0043] The detection portion 30C is a linear portion of the vibration sensor 30 that detects the vibration of the sub-bearing 23. The detection portion 30C is located between the base-end-side fixing portion 30A and the tip-end-side fixing portion 30B and extends linearly. The detection portion 30C is formed of a linear material having a piezoelectric effect and extends in the circumferential direction in a state of being in contact with the outer peripheral surface of the outer ring 23B of the sub-bearing 23. The detection portion 30C outputs an electrical vibration detection signal corresponding to the vibration of the sub-bearing 23. Thereby, the vibration sensor 30 detects the vibration of the sub-bearing 23.

[0044] The flexible member 32 is inserted into the sensor housing portion 24D of the spacer 24 in a state of covering the detection portion 30C of the vibration sensor 30. The flexible member 32 is formed in a substantially annular shape using, for example, a fluororubber sponge. The flexible member 32 is not limited to a fluororubber sponge and may be formed using other materials having desired heat resistance, cold resistance, and oil resistance. As shown in FIGS. 2 to 5, the flexible member 32 is inserted between the outer peripheral surface of the outer ring 23B of the sub-bearing 23 and the inner peripheral surface of the sensor housing portion 24D in a state of covering the detection portion 30C of the vibration sensor 30. Thereby, the flexible member 32 is attached between the detection portion 30C of the vibration sensor 30 and the spacer 24.

[0045] As shown in FIG. 3, the bearing monitoring device 33 is electrically connected to the vibration sensor 30. The bearing monitoring device 33 includes, for example, a microcomputer and executes a program stored in a storage unit (not shown). Thereby, the bearing monitoring device 33 detects the vibration of the sub-bearing 23 based on the vibration detection signal from the vibration sensor 30. At this time, the bearing monitoring device 33 acquires the frequency components of the vibration detection signal. The bearing monitoring device 33 removes the fundamental frequency component corresponding to the rotational speed of the rotating shaft 4 and the frequency components that are integer multiples thereof from the frequency components of the vibration detection signal. The bearing monitoring device 33 determines whether or not the magnitude of the remaining frequency components is greater than a predetermined determination value. When the magnitude of the remaining frequency components is greater than the determination value, the bearing monitoring device 33 determines that an abnormality has occurred in the sub-bearing 23 and outputs an error signal. The determination value may be, for example, a fixed value determined in advance by experiments or the like, or a value determined relatively according to the magnitude of the fundamental frequency component.

[0046] Next, the method of attaching the vibration sensor 30 will be described. The vibration sensor 30 is attached to the sub-bearing 23 with the seal cover 26 or the like removed. At this time, the detection unit 30C of the vibration sensor 30 is wound around the outer peripheral surface of the outer ring 23B of the sub-bearing 23 with the bearing nut 25 loosened. On the other hand, the base-end side fixing portion 30A and the tip-end side fixing portion 30B of the vibration sensor 30 are pulled out to the outside of the casing body 2 through the insertion hole 29. At this time, compression fittings 31 are attached to the base-end side fixing portion 30A and the tip-end side fixing portion 30B. Therefore, by inserting the compression fittings 31 into the insertion hole 29 and sealing the insertion hole 29, the base-end side fixing portion 30A and the tip-end side fixing portion 30B of the vibration sensor 30 are fixed to the casing body 2. Along with this, the detection unit 30C of the vibration sensor 30 is fixed in a state of being in contact with the outer peripheral surface of the outer ring 23B of the sub-bearing 23.

[0047] Also, after the vibration sensor 30 is wound around the sub-bearing 23, the flexible member 32 is inserted into the sensor housing portion 24D of the spacer 24. At this time, the flexible member 32 is attached into the sensor housing portion 24D so that there is no gap between the outer peripheral surface of the outer ring 23B of the sub-bearing 23 and the inner peripheral surface of the sensor housing portion 24D in a state of covering the detection unit 30C of the vibration sensor 30.

[0048] As shown in FIG. 5, after the vibration sensor 30 and the flexible member 32 are attached, the bearing nut 25 is tightened onto the male screw portion 4C of the rotating shaft 4. At this time, the inner ring 23A of the sub-bearing 23 is displaced in a direction approaching the main bearing 22. As a result, a force acting radially outward is applied to the tapered roller 23C of the sub-bearing 23. Consequently, a force causing the outer ring 23B of the sub-bearing 23 to bulge radially outward acts thereon. For this reason, the detection portion 30C of the vibration sensor 30 also tends to bulge radially outward, similar to the outer ring 23B. However, the detection portion 30C of the vibration sensor 30 is constrained by the flexible member 32, and the flexible member 32 is constrained by the spacer 24. Therefore, the detection portion 30C of the vibration sensor 30 is pressed against the outer peripheral surface of the outer ring 23B of the sub-bearing 23 by the flexible member 32. The inner diameter dimension of the flexible member 32 is appropriately set in advance so that an appropriate pressing force is generated on the vibration sensor 30 when the bearing nut 25 is tightened. Thereby, when the vibration sensor 30 is attached to the sub-bearing 23, the vibration sensor 30 can be easily installed on the hydraulic pump 1 in a state where an appropriate pressing force is applied to the vibration sensor 30. Also, during measurement, the vibration sensor 30 can be appropriately fixed to the outer peripheral surface of the sub-bearing 23.

[0049] After the tightening of the bearing nut 25 is completed, the seal cover 26 and the seal member 28 are attached. Thereafter, the ring retaining 27 is attached to the casing body 2. Thereby, the seal cover 26 is fixed to the casing body 2 and covers the bearing housing portion 2A of the casing body 2 in a state of covering one axial side of the sub-bearing 23.

[0050] The hydraulic pump 1 according to the embodiment has the configuration as described above. Next, its operation will be described.

[0051] When the rotary shaft 4 is rotationally driven by a prime mover (not shown) such as an engine or a motor, the cylinder block 5 rotates together with the drive disk 4B of the rotary shaft 4. Since the rotation center axis of the cylinder block 5 is inclined with respect to the rotary shaft 4, as the cylinder block 5 rotates, the piston 7 reciprocates within each cylinder hole 5B. The cylinder block 5 rotationally slides on the sliding spherical surface portion 8B that serves as the switching surface of the valve plate 8, and the cylinder ports 5D of each cylinder hole 5B provided in the cylinder block 5 intermittently communicate with a pair of supply / discharge ports provided in the valve plate 8, that is, the suction port serving as the low-pressure port and the discharge port serving as the high-pressure port.

[0052] During the half rotation in which the cylinder port 5D communicates with the suction port, which is the port on the low-pressure side (suction side) of each supply / discharge port, the piston 7 protrudes from the cylinder hole 5B, which is the suction stroke, and the hydraulic oil is sucked into the cylinder hole 5B. That is, in the suction stroke of the piston 7, the oil fluid is sucked into the cylinder hole 5B from the hydraulic oil tank through the suction port of the valve plate 8. On the other hand, during the half rotation in which the cylinder port 5D communicates with the discharge port, which is the port on the high-pressure side (discharge side) of each supply / discharge port, the piston 7 enters the cylinder hole 5B, which is the discharge stroke, and the hydraulic oil sucked into the cylinder hole 5B during the suction stroke is pressurized and discharged (ejected) to the discharge port of the valve plate 8. That is, in the discharge stroke of the piston 7, the pressure oil is discharged from the cylinder hole 5B, and this pressure oil is supplied to various hydraulic devices (not shown) connected to the downstream side of the hydraulic pipeline through the discharge port of the valve plate 8.

[0053] By the way, when the cylinder block 5 rotates, due to the hydraulic reaction force, the piston 7 pushes the drive disk 4B. The force pushing the drive disk 4B is transmitted to the main bearings 21, 22 and the sub-bearing 23, and then a part of the force also acts on the spacer 24 and the seal cover 26, and finally is received by the casing body 2 and the ring retaining 27. In order to apply pressure to the sub-bearing 23, the main bearings 21, 22 and the sub-bearing 23 are constrained by the drive disk 4B and the bearing nut 25.

[0054] The vibration sensor 30 is disposed between the sub-bearing 23 and the spacer 24 and is attached along the outer circumference of the sub-bearing 23. Both ends of the vibration sensor 30 are drawn out to the outside of the casing body 2 through the insertion holes 29 formed in the spacer 24 and the casing body 2. In order to press the vibration sensor 30 against the sub-bearing 23, a flexible member 32 is provided between the vibration sensor 30 and the spacer 24.

[0055] As the rotating shaft 4 rotates, vibrations occur in the sub-bearing 23. At this time, in addition to the vibration of the fundamental frequency corresponding to the rotational speed of the rotating shaft 4 occurring in the sub-bearing 23, vibrations that are integer multiples of the fundamental frequency also occur. On the other hand, the vibration sensor 30 is wound around the outer ring 23B of the sub-bearing 23. Thereby, the vibration sensor 30 detects the vibration of the sub-bearing 23 and outputs a vibration detection signal corresponding to the vibration.

[0056] The bearing monitoring device 33 detects whether or not an abnormality has occurred in the sub-bearing 23 based on the vibration detection signal from the vibration sensor 30. As shown in FIG. 6, when the hydraulic pump 1 is normal, the vibration detection signal from the vibration sensor 30 includes a fundamental frequency component corresponding to the rotational speed of the rotating shaft 4 and frequency components that are integer multiples thereof (the peaks of the solid lines in FIG. 6). At this time, in the fundamental frequency component and its integer multiple frequency components, the amplitude of the vibration detection signal becomes large, and in other frequency components, the amplitude becomes small.

[0057] On the contrary, as shown in Fig. 7, when the hydraulic pump 1 is abnormal, the vibration detection signal from the vibration sensor 30 generates a peak at a frequency different from both the fundamental frequency component and the frequency components that are integer multiples of it (the peaks of the solid line in Fig. 7) (the peaks of the dotted line in Fig. 7). This peak corresponds to the frequency component of the abnormal vibration. At this time, the amplitude of the frequency component of the abnormal vibration becomes larger compared to the normal state. Therefore, the bearing monitoring device 33 determines whether or not the magnitude of the frequency component of this abnormal vibration exceeds a predetermined determination value. When the magnitude of the frequency component of the abnormal vibration becomes larger than the determination value, the bearing monitoring device 33 determines that an abnormality has occurred in the sub-bearing 23 and outputs an error signal. As a result, the abnormality of the hydraulic pump 1 can be detected at an early stage.

[0058] Thus, in the present embodiment, the hydraulic pump 1 includes a casing body 2 (casing), a cylinder block 5 rotatably provided within the casing body 2 and having a plurality of cylinder holes 5B that are circumferentially spaced apart and extend axially, a plurality of pistons 7 reciprocally inserted into each of the cylinder holes 5B of the cylinder block 5, a rotating shaft 4 rotatably provided within the casing body 2, extending in a direction inclined from the central axis of rotation of the cylinder block 5, connected to the plurality of pistons 7, and rotating together with the cylinder block 5, and a plurality of tapered roller bearings (main bearings 21, 22, sub-bearing 23) provided on the casing body 2 for rotatably supporting the rotating shaft 4.

[0059] In the present embodiment, the hydraulic pump 1 is characterized by including an insertion hole 29 provided in the casing body 2 and extending toward the sub-bearing 23 serving as a detected bearing consisting of any one of the plurality of tapered roller bearings, and a vibration sensor 30 having a linear detection portion 30C that is inserted through the insertion hole 29, attached to the casing body 2, contacts the outer peripheral surface of the sub-bearing 23, and extends along the outer peripheral surface of the sub-bearing 23 to detect the vibration of the sub-bearing 23.

[0060] Therefore, the vibration sensor 30 can be attached to the sub-bearing 23 even when the sub-bearing 23 is inside the casing body 2. Accordingly, compared with the case where the vibration sensor 30 is fixed to the sub-bearing 23 using an adhesive and then the sub-bearing 23 is attached to the casing body 2, damage to the vibration sensor 30 during attachment can be prevented. In addition, the vibration sensor 30 can be easily replaced. Thereby, the attachability of the vibration sensor 30 to the sub-bearing 23 can be improved, and productivity and maintainability can be enhanced.

[0061] In the present embodiment, the plurality of tapered roller bearings include the main bearing 22 and the sub-bearing 23 facing each other, the bearing to be detected is the sub-bearing 23, the outer ring 23B of the sub-bearing 23 is fitted into the spacer 24, and the inner ring 23A is in contact with the bearing nut 25. The sub-bearing 23 is attached to the casing body 2, and an annular flexible member 32 is provided between the spacer 24 and the vibration sensor 30. By tightening the bearing nut 25, the outer diameter of the outer ring 23B of the sub-bearing 23 expands, and the linear detection portion 30C of the vibration sensor 30 is sandwiched between the inner peripheral surface of the flexible member 32 and the outer peripheral surface of the outer ring 23B of the sub-bearing 23.

[0062] Therefore, by tightening the bearing nut 25, the force pressing the vibration sensor 30 against the outer peripheral surface of the outer ring 23B of the sub-bearing 23 increases, and an appropriate pressing load acts on the vibration sensor 30. As a result, the vibration of the sub-bearing 23 during operation can be appropriately monitored, and abnormalities of the sub-bearing 23 can be detected at an early stage.

[0063] At this time, the sub-bearing 23 is formed to have an outer diameter smaller than those of the main bearings 21 and 22, and is disposed at a position farther from the cylinder block 5 than the main bearings 21 and 22.

[0064] Therefore, the sub-bearing 23 is more likely to experience wear and damage than the main bearings 21 and 22. In contrast, in this embodiment, since the vibration sensor 30 is attached to the sub-bearing 23, it is possible to grasp the early damage of the hydraulic pump 1 itself by detecting an abnormality in the sub-bearing 23.

[0065] Further, the vibration sensor 30 is constituted by a piezoelectric wire sensor. For this reason, the vibration sensor 30 does not need to be rigidly fixed to the sub-bearing 23 by, for example, adhesion or the like, and can detect the vibration of the sub-bearing 23 by being wound around the outer peripheral surface of the sub-bearing 23. Therefore, the attachability of the vibration sensor 30 can be improved.

[0066] In the swashplate type hydraulic rotary machine system of this embodiment, a bearing monitoring device 33 is provided which is connected to the vibration sensor 30 and monitors the state of the sub-bearing 23 based on the vibration detection signal output from the vibration sensor 30.

[0067] When the hydraulic pump 1 is abnormal, the vibration detection signal from the vibration sensor 30 has a large frequency component of abnormal vibration different from both the fundamental frequency component corresponding to the rotational speed of the rotating shaft 4 and the frequency components that are integer multiples thereof. For this reason, the bearing monitoring device 33 can detect an abnormality in the sub-bearing 23 by determining whether or not the magnitude of the frequency component of this abnormal vibration exceeds a predetermined determination value.

[0068] In the embodiment, the case where the tip-side fixing portion 30B of the vibration sensor 30 is pulled out and fixed outside the casing main body 2 has been described as an example. However, the present invention is not limited to this. For example, the tip-side fixing portion 30B of the vibration sensor 30 may be configured to be fixed inside the insertion hole 29. Further, for example, as in the modification shown in FIG. 8, the tip-side fixing portion 40B of the vibration sensor 40 may be configured to be fixed in a state of being accommodated in the spacer 24. In this case, the base-end side fixing portion 40A of the vibration sensor 40 is fixed to the opening end portion of the insertion hole 29 using the compression fitting 31. Further, the linear detection portion 40C of the vibration sensor 40 extends along the outer peripheral surface of the outer ring 23B of the sub-bearing 23 and is attached to the sensor accommodation portion 24D of the spacer 24.

[0069] In the embodiment, the case where the vibration sensor 30 is attached to the sub-bearing 23 has been described as an example. However, the present invention is not limited to this. For example, if the vibration sensor can be attached by insertion from the insertion hole, the vibration sensor may be attached to the main bearing.

[0070] In the embodiment, the case where the flexible member 32 is provided between the spacer 24 and the vibration sensor 30 has been described as an example. However, the present invention is not limited to this. If an appropriate pressing force can be applied to the vibration sensor 30, the flexible member may be omitted.

[0071] In the embodiment, the case where the sub-bearing 23 is provided on the casing main body 2 via the spacer 24 has been described as an example. However, the present invention is not limited to this. When the spacer and the casing main body are integrated, the spacer may be omitted and the sub-bearing may be directly attached to the casing main body.

[0072] In the embodiment, the case where the vibration sensor 30 is a piezo-wire sensor has been described as an example. However, the present invention is not limited to this. Various sensors having a linear detection portion for detecting vibration (for example, an optical fiber sensor, etc.) can be applied as the vibration sensor.

[0073] In the embodiment, a variable displacement hydraulic pump 1 is taken as an example of an inclined shaft type hydraulic rotary machine for explanation. However, it is not limited to this. For example, a fixed displacement hydraulic pump may be used. Further, in the embodiment, the hydraulic pump 1 is taken as an example of an inclined shaft type hydraulic rotary machine for explanation. However, it is not limited to this. For example, it may be applied to an inclined shaft type hydraulic motor or the like as an inclined shaft type hydraulic rotary machine.

[0074] In the embodiment, the case where the hydraulic pump 1 is applied to a hydraulic excavator is taken as an example for explanation. However, it is not limited to this. For example, it may be applied to construction machines other than hydraulic excavators such as hydraulic cranes and wheel loaders.

Explanation of Reference Numerals

[0075] 1 Hydraulic pump (Inclined shaft type hydraulic rotary machine) 2 Casing body 3 Head casing 4 Rotating shaft 5 Cylinder block 5B Cylinder hole 7 Piston 21, 22 Main bearings 23 Sub-bearing (Detected bearing) 24 Spacer 29 Insertion hole 30 Vibration sensor 30A Base end side fixing part 30B Tip end side fixing part 30C Detection part 32 Flexible member 33 Bearing monitoring device

Claims

1. A casing, a cylinder block rotatably provided within the casing and having a plurality of cylinder holes that are circumferentially spaced apart and axially extend, a plurality of pistons reciprocally inserted into each of the cylinder holes of the cylinder block, a rotating shaft rotatably provided within the casing, extending in a direction inclined from the central axis of rotation of the cylinder block, connected to the plurality of pistons, and rotating together with the cylinder block, a plurality of tapered roller bearings provided in the casing for rotatably supporting the rotating shaft, in an axial piston type hydraulic rotary machine, an insertion hole provided in the casing and extending toward a detected bearing that is one of the plurality of tapered roller bearings, a vibration sensor inserted through the insertion hole and attached to the casing, having a linear detection portion that contacts the outer peripheral surface of the detected bearing and extends along the outer peripheral surface of the detected bearing to detect vibration of the detected bearing, the plurality of tapered roller bearings include a main bearing and a sub-bearing facing each other, the detected bearing is the sub-bearing, the sub-bearing is attached to the casing with the outer ring fitted to a spacer and the inner ring contacting a bearing nut, an annular flexible member is provided between the spacer and the vibration sensor, the outer diameter of the outer ring of the sub-bearing is expanded by tightening the bearing nut, and the detection portion of the vibration sensor is sandwiched between the inner peripheral surface of the flexible member and the outer peripheral surface of the outer ring of the sub-bearing, characterized in that it is an axial piston type hydraulic rotary machine.

2. The sub-bearing is formed with an outer diameter dimension smaller than that of the main bearing and is arranged at a position farther from the cylinder block than the main bearing, characterized in that it is the axial piston type hydraulic rotary machine according to claim 1.

3. The vibration sensor is a piezo wire sensor, characterized in that it is the axial piston type hydraulic rotary machine according to claim 1.

4. A casing, a cylinder block rotatably provided within the casing and having a plurality of cylinder holes that are circumferentially spaced apart and axially extend, ) a plurality of pistons reciprocally inserted into each of the cylinder holes of the cylinder block, A rotating shaft that is rotatably provided within the casing, extends in a direction inclined from the central axis of rotation of the cylinder block, is connected to the plurality of pistons, and rotates together with the cylinder block; A plurality of tapered roller bearings provided in the casing for rotatably supporting the rotating shaft; An insertion hole provided in the casing and extending toward a detected bearing that is one of the plurality of tapered roller bearings; A vibration sensor that is inserted through the insertion hole and attached to the casing, has a linear detection portion that extends along the outer peripheral surface of the detected bearing while contacting the outer peripheral surface of the detected bearing to detect vibration of the detected bearing; A bearing monitoring device that is connected to the vibration sensor and monitors the state of the detected bearing based on a vibration detection signal output from the vibration sensor. The system includes: The plurality of tapered roller bearings include a main bearing and a sub-bearing facing each other; The detected bearing is the sub-bearing; The sub-bearing is attached to the casing in a state where an outer ring is fitted into a spacer and an inner ring contacts a bearing nut; An annular flexible member is provided between the spacer and the vibration sensor; An inclined-axis hydraulic rotary machine system, characterized in that tightening of the bearing nut expands the outer diameter of the outer ring of the sub-bearing, and the detection portion of the vibration sensor is sandwiched between the inner peripheral surface of the flexible member and the outer peripheral surface of the outer ring of the sub-bearing.

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