CN111577524A

CN111577524A - Hydraulic motor

Info

Publication number: CN111577524A
Application number: CN202010095659.5A
Authority: CN
Inventors: 清家雄二
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2019-02-18
Filing date: 2020-02-17
Publication date: 2020-08-25
Anticipated expiration: 2040-02-17
Also published as: JP2020133474A; CN111577524B; KR20200100534A; JP7281918B2

Abstract

The invention provides a hydraulic motor which can be miniaturized and can properly measure the rotating speed. The hydraulic motor (20) is provided with: a housing (23); a cylinder (30) which is housed in the housing (23) and is rotatable; a cylinder-side friction plate (61) that is restricted from rotating relative to the cylinder (30) about the rotational axis (A) of the cylinder (30); a housing side plate (71) that is restricted from rotating relative to the housing (23), the housing side plate (71) at least partially overlapping the cylinder side friction plate (61) in the direction of the axis of rotation; a pressing mechanism (80) which presses the cylinder side friction plate (61) and the housing side plate (71) against each other along the rotation axis direction; and a detector (90) that is fixed to the housing (23) and detects the rotation of at least 1 of the cylinder-side friction plates (61).

Description

Hydraulic motor

Technical Field

The present invention relates to a hydraulic motor used for construction vehicles and the like.

Background

In a wide range of fields such as construction vehicles, a hydraulic motor is used as a mechanism for generating driving force. As an example, the hydraulic motor includes: a cylinder block formed with a plurality of cylinder bores extending in the rotational axis direction; a piston movably held in each cylinder hole; and a swash plate for rotating the cylinder block about the rotation axis by movement of each piston in each cylinder bore.

In such a hydraulic motor, the rotation speed of the cylinder may be measured in order to monitor the operating state of the hydraulic motor. JP2009-174504a discloses the following technique: the outer peripheral surface of the cylinder is provided with a detection section, and the rotation speed of the cylinder is measured by detecting the detection section with a rotation sensor disposed in the housing in a state of facing the detection section.

However, when the hydraulic motor is further miniaturized, it is considered that the rotation sensor and any one of the components disposed in the hydraulic motor interfere with each other. In this case, it is difficult to appropriately dispose the rotation sensor in the hydraulic motor.

Disclosure of Invention

The present invention has been made in view of the above points, and an object thereof is to provide a hydraulic motor which can be miniaturized and whose rotation speed can be appropriately measured.

The hydraulic motor of the present invention includes:

a housing;

a cylinder housed in the housing and rotatable;

a cylinder block side friction plate whose rotation relative to the cylinder block about a rotation axis of the cylinder block is restricted;

a housing side plate whose rotation relative to the housing is restricted, the housing side plate at least partially overlapping the cylinder block side friction plate in the rotation axis direction;

a pressing mechanism that presses the cylinder-side friction plate and the housing-side plate against each other along the rotation axis direction; and

and a detector fixed to the housing and detecting rotation of at least 1 of the cylinder block side friction plates.

In the hydraulic motor of the present invention, it is also possible,

the hydraulic motor has a plurality of cylinder-side friction plates,

the detector detects rotation of the cylinder-side friction plate that is closest to the pressing mechanism in a direction along the rotation axis, among the plurality of cylinder-side friction plates.

In the hydraulic motor of the present invention, it is also possible,

the thickness of the cylinder block side friction plate closest to the pressing mechanism is larger than the thickness of the other cylinder block side friction plates.

In the hydraulic motor of the present invention, it is also possible,

the pressing mechanism includes:

a piston member that transmits a pressing force to the cylinder-side friction plate and the housing-side plate; and

a limiting member that limits rotation of the piston member about the rotation axis.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a hydraulic motor that can be miniaturized and can appropriately measure the number of rotations.

Drawings

Fig. 1 is a diagram for explaining an embodiment of the present invention, and is a diagram showing a cross section of a hydraulic drive device in which a hydraulic motor is incorporated.

Fig. 2 is an enlarged view of a portion with II in fig. 1.

Fig. 3 is a view showing a cross section corresponding to the line III-III of fig. 1.

Description of the reference numerals

10. A hydraulic drive device; 12. a back pressure valve; 20. a hydraulic motor; 21. a rotating shaft; 23. a housing; 25. a fixed block; 25A, mounting holes; 27. rotating the block; 29. a cover block; 30. a cylinder body; 32. a cylinder bore; 34. a recess; 40. a piston; 50. a sloping plate; 60. a brake mechanism; 61. a cylinder side friction plate; 63. a main body; 65. a convex portion; 67. a lining material; 69. a detected part; 71. a housing side plate; 80. a pushing mechanism; 82. a piston member; 84. a pressing member; 86. a restraining member; 88. a sealing member; 90. a detector; A. a rotation axis; C. a pressure chamber.

Detailed Description

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, the scale, the vertical and horizontal size ratios, and the like are appropriately changed and exaggerated with respect to the actual size and the like for the convenience of illustration and easy understanding.

In addition, terms such as "parallel", "orthogonal" and "the same", lengths, angles, and the like used in the present specification, conditions of shape and geometry, and terms for determining the degrees thereof are not limited to strict meanings, and are interpreted to include ranges of degrees to which the same functions can be expected.

Fig. 1 to 3 are diagrams for explaining an embodiment of the present invention. Fig. 1 is a cross-sectional view of a hydraulic drive apparatus 10 incorporating a hydraulic motor 20, fig. 2 is an enlarged view of a portion with II in fig. 1, and fig. 3 is a cross-sectional view corresponding to a line III-III in fig. 1. The hydraulic drive device 10 of the present embodiment is used to drive a hoist unit provided in a work vehicle as an example of a work machine, and the application of the hydraulic drive device 10 is not limited to this, and may be used to drive a travel unit or a swing unit of the work vehicle, for example.

The hydraulic drive device 10 shown in fig. 1 includes a hydraulic motor 20 and a back pressure valve 12 incorporated in the hydraulic motor 20. In fig. 1, a part of the hydraulic motor 20 and the back pressure valve 12 are shown in a cross section along the axial direction of the rotary shaft 21 of the hydraulic motor 20. Here, the "axial direction (rotation axis direction)" refers to a direction extending along the rotation axis a of the rotation shaft 21 or a direction parallel to the direction extending along the rotation axis a. In the following description, when simply referred to as the axial direction, the direction refers to the axial direction of the rotary shaft 21. A direction perpendicular to the rotation axis a is referred to as a radial direction, and a direction rotating around the rotation axis a is referred to as a circumferential direction.

The back pressure valve 12 is disposed on one side (left side in fig. 1) in the axial direction with respect to the hydraulic motor 20. The back pressure valve 12 is provided for driving the hydraulic motor 20 to supply and discharge the hydraulic oil, and for controlling the stop of the hydraulic motor 20 by suppressing the flow of the hydraulic oil due to the inertia of the hydraulic motor 20, the inertia of the load, and the weight of the hydraulic oil after the supply of the hydraulic oil to the hydraulic motor 20 is stopped.

The back pressure valve 12 comprises: a valve body 14 in which a plurality of oil passages are formed; and a check valve 16 housed in the valve body 14. The valve body 14 is formed with a 1 st oil supply/discharge passage and a 2 nd oil supply/discharge passage. The 1 st supply and drain passage has an external communication port selectively communicating with a hydraulic pump or a discharge tank, not shown, and an internal communication port communicating with the hydraulic motor 20, and the 2 nd supply and drain passage has an external communication port selectively communicating with the hydraulic pump or the discharge tank and an internal communication port communicating with the hydraulic motor 20.

When the external communication port of the 1 st supply/discharge oil passage and the external communication port of the 2 nd supply/discharge oil passage are connected to one of the hydraulic pumps in response to an operation of a switching valve, not shown, the other is connected to the discharge tank. When the external communication port of the 1 st supply/drain passage is connected to the hydraulic pump, the internal communication port of the 1 st supply/drain passage is connected to the hydraulic motor 20 and is supplied with the hydraulic oil. On the other hand, when the external communication port of the 2 nd supply/discharge oil passage communicates with the hydraulic pump, the internal communication port of the 2 nd supply/discharge oil passage is connected to the hydraulic motor 20 to supply the hydraulic oil. In this example, in the former case, the hoist unit is reeled up, and in the latter case, the hoist unit is reeled down.

Next, the hydraulic motor 20 will be described. In the present embodiment, the hydraulic motor 20 is a hydraulic motor with a reduction gear including a reduction gear not shown. The hydraulic motor 20 includes a rotary shaft 21, a housing 23, a cylinder block 30, a piston 40, a swash plate 50, a brake mechanism 60, a detector 90, and a speed reduction mechanism not shown. The hydraulic motor 20 is not limited to this, and may be a hydraulic motor that does not include a speed reducer.

The housing 23 has: a fixed block 25; a rotating block 27 attached to the fixed block 25; and a cover block 29 mounted with respect to the fixed block 25 from the side opposite to the rotation block 27. The rotating block 27 is configured to be rotatable relative to the fixed block 25 about the rotation axis a of the rotating shaft 21. The cover block 29 is fixed relative to the fixing block 25. The housing 23 accommodates the rotary shaft 21, the cylinder block 30, the piston 40, the swash plate 50, the cylinder block side friction plate 61, the housing side plate 71, the pressing mechanism 80, the detector 90, and the speed reduction mechanism.

The rotary shaft 21 protrudes from the fixed block 25 to one side in the axial direction, and protrudes from the fixed block 25 to the other side (in fig. 1, the right side) in the axial direction. A housing hole 29A is formed in a surface of the cover block 29 facing the fixed block 25. One end portion of the rotating shaft 21 in the axial direction is housed in the housing hole 29A. A 1 st bearing 29B is disposed between the housing hole 29A and the rotary shaft 21. Thereby, the one end portion of the rotating shaft 21 in the axial direction is supported rotatably about the rotation axis a by the 1 st bearing 29B in the housing hole 29A. The rotary shaft 21 is rotatably supported by the fixed block 25 via another bearing inside the fixed block 25, although not shown. Further, a recess 29C cut out from a surface of the cover block 29 facing the other side in the axial direction (a surface facing the fixed block 25 side) facing the one side in the axial direction is provided at the other side portion in the axial direction of the cover block 29. The recess 29C receives at least a part of a pressing member 84 of the pushing mechanism 80 discussed later.

The cylinder 30 is disposed radially outward of the rotary shaft 21, and is held by the rotary shaft 21 so as to rotate together with the rotary shaft 21. In the illustrated example, the cylinder 30 is retained to the rotary shaft 21 by spline coupling. Thereby, the relative movement of the cylinder block 30 with respect to the circumferential direction of the rotary shaft 21 is restricted. In other words, the cylinder block 30 and the rotary shaft 21 are configured to rotate together about the rotation axis a. The cylinder 30 is formed in a shape extending over the entire circumference in the circumferential direction on the radially outer side of the rotary shaft 21 when viewed in the axial direction. A plurality of cylinder holes 32 extending in the axial direction are formed in the cylinder block 30. The plurality of cylinder holes 32 are arranged on the same circumference at intervals in the circumferential direction.

As clearly shown in fig. 2 and 3, a plurality of recesses 34 arranged in the circumferential direction are provided on the outer circumferential surface of the cylinder block 30. In the illustrated example, the recess 34 is formed as a groove extending in the axial direction. The recess 34 has a shape obtained by cutting the cylinder 30 in an arc shape (fan shape) from the outer peripheral surface in a cross section orthogonal to the axial direction. The recess 34 is located radially outward with respect to the cylinder holes 32 and between two adjacent cylinder holes 32 in the circumferential direction. That is, the number of the cylinder holes 32 provided in the cylinder block 30 is the same as the number of the recesses 34. The plurality of recesses 34 are arranged at a constant angular pitch along the circumferential direction. The concave portion 34 engages with a later-described convex portion 65 provided in the cylinder-side friction plate 61, and has a function of restricting relative movement of the cylinder-side friction plate 61 with respect to the cylinder 30 in the circumferential direction.

The pistons 40 are held by the plurality of cylinder holes 32, respectively, and are movable in the axial direction. By supplying the hydraulic oil, which has flowed in from the hydraulic pump via the back pressure valve 12, from the head block 29 side to the cylinder hole 32, the pistons 40 move toward the swash plate 50 side, respectively. The pistons 40 are pushed by the inclined surfaces 51 of the swash plate 50, which will be described later, and move toward the head block 29, and the hydraulic oil in the cylinder bores 32 is discharged. Shoes 41 are attached to the respective pistons 40 at the end portions thereof on the swash plate 50 side so as to be able to swing. The shoes 41 move on the inclined surface 51 of the swash plate 50 along the inclined surface 51.

The swash plate 50 has a slope 51 for rotating and rotating the piston 40 in the circumferential direction on the cylinder block 30 side. The inclined surface 51 is inclined with respect to a plane orthogonal to the rotation axis a. The piston 40 abuts against the inclined surface 51 via the shoe 41. In addition, a through hole 53 through which the rotary shaft 21 passes is formed in the swash plate 50. When the piston 40 moves toward the swash plate 50, the inclined surface 51 gives a reaction force in the circumferential direction to the piston 40. Accordingly, when the working oil is supplied to the cylinder hole 32 and the corresponding piston 40 advances from the cylinder hole 32, the piston 40 rotates in the circumferential direction, and accordingly, the cylinder block 30 and the rotary shaft 21 rotate integrally.

The end of the rotating shaft 21 on the other side in the axial direction (the right side in fig. 1) is connected to a speed reduction mechanism (not shown). The speed reduction mechanism includes, for example, a planetary gear speed reduction mechanism, and reduces the rotation speed of the rotary shaft 21 to transmit the rotation speed to the rotary block 27. The rotation block 27 is rotatably supported by the fixed block 25, and rotates about the rotation axis a while being transmitted from the rotation shaft 21 through the speed reduction mechanism. An annular flange 27A extending radially outward is formed on the rotary block 27, and a drum, not shown, is attached to the flange 27A. The drum rotates with the rotation of the rotation block 27, and a winch unit and the like, not shown, are driven.

The brake mechanism 60 includes: a cylinder-side friction plate 61 engaged with the cylinder 30; a housing side plate 71 engaged with the housing 23; and a pressing mechanism 80 that presses the cylinder-side friction plate 61 and the housing-side plate 71 against each other along the rotation axis direction.

The brake mechanism 60 has a plurality of cylinder side friction plates 61. The cylinder-side friction plate 61 is a plate-shaped member having a plate surface perpendicular to the rotation axis a and having an annular shape when viewed from the axial direction. The brake mechanism 60 of the present embodiment includes a plurality of cylinder-side friction plates 61 arranged in the axial direction. Each cylinder side friction plate 61 includes a main body 63 and lining materials 67 provided on one and the other surfaces of the main body 63 in the axial direction. The lining 67 is provided to improve the wear resistance of the cylinder side friction plate 61.

A convex portion 65 protruding radially inward is formed on the inner peripheral portion of the main body 63. In the example shown in fig. 3, the cylinder-side friction plate 61 has a plurality of protrusions 65 arranged along the circumferential direction in the inner circumferential portion. The plurality of protrusions 65 are arranged with a constant angular pitch along the circumferential direction. In particular, the angular pitch of the convex portions 65 is the same as the angular pitch of the concave portions 34 provided on the outer peripheral surface of the cylinder 30. In a state where the cylinder-side friction plate 61 is assembled to the cylinder 30, at least a part of the convex portion 65 is positioned in the concave portion 34. In particular, at least a portion of the projection 65 including the tip portion located radially inward is located within the recess 34. Thereby, the convex portion 65 engages with the concave portion 34, and the relative movement of the cylinder side friction plate 61 with respect to the cylinder 30 in the circumferential direction is restricted. On the other hand, the convex portion 65 is relatively movable in the axial direction along the concave portion 34 formed as a groove portion extending in the axial direction. That is, the cylinder-side friction plate 61 is relatively movable in the axial direction with respect to the cylinder 30.

At least 1 of the plurality of cylinder side friction plates 61 is provided with a detected portion 69. In the present embodiment, the detection target portion 69 is provided on the cylinder side friction plate 61A (located at the position closest to the one side in the axial direction) of the plurality of cylinder side friction plates 61 that is closest to the pressing mechanism 80 in the axial direction. As shown in fig. 1 and 2, the thickness of the cylinder side friction plate 61A (the thickness of the main body 63A) is larger than the thickness of the other cylinder side friction plates 61 (the thickness of the main body 63). The detection section 69 is provided in the outer peripheral portion of the main body 63A. The detected portion 69 is provided to detect the rotation of the cylinder side friction plate 61A by the detector 90. The specific configuration of the detected part 69 is not particularly limited as long as it can be detected by the detector 90. As an example, the detection target portion 69 may be a detection target portion in which different magnetic poles (N pole and S pole) are alternately arranged on the outer peripheral surface of the main body 63A in the circumferential direction. In other words, the detection target portion 69 can be a detection target portion including different magnetic poles alternately arranged in the circumferential direction. As another example, the detection target portion 69 may be a detection target portion in which convex portions and concave portions are alternately arranged on the outer peripheral surface of the main body 63A in the circumferential direction. In other words, the detection target portion 69 can be a detection target portion including convex portions and concave portions alternately arranged in the circumferential direction.

The case side plate 71 is a plate-shaped member having a plate surface perpendicular to the rotation axis a and having an annular shape when viewed from the axis direction. The brake mechanism 60 of the present embodiment includes a plurality of housing side plates 71 aligned in the axial direction. The cylinder-side friction plates 61 and the housing-side plates 71 are alternately arranged along the axial direction, and the housing-side plates 71 and the cylinder-side friction plates 61 at least partially overlap in the rotational axis direction. Further, the cylinder-side friction plate 61A is located at a position closest to the pressing mechanism 80 in the axial direction among the plurality of cylinder-side friction plates 61 and the plurality of housing side plates 71.

The relative rotation of the housing side plate 71 with respect to the housing 23 (fixed block 25) about the rotation axis a is restricted. Means for restricting the relative rotation of the case side plate 71 with respect to the case 23 is not particularly limited. In the present embodiment, a plurality of convex portions arranged in the circumferential direction are provided on the outer peripheral portion of the case side plate 71. In addition, a concave portion corresponding to each convex portion is formed in the fixing block 25 of the housing 23. The recess is formed as a groove portion extending in the axial direction. Further, the convex portion of the case side plate 71 is engaged with the concave portion of the fixed block 25, whereby the relative rotation of the case side plate 71 with respect to the case 23 is restricted. On the other hand, the convex portion of the case side plate 71 is relatively movable in the axial direction along the concave portion of the fixed block 25. That is, the housing side plate 71 is relatively movable in the axial direction with respect to the housing 23.

The pressing mechanism 80 includes: a piston member 82; a pressing member 84 that presses the piston member 82 toward the cylinder-side friction plate 61 and the housing-side plate 71; a restricting member 86 that restricts relative rotation of the piston member 82 about the rotation axis a with respect to the housing 23; and a sealing member 88 that seals between the piston member 82 and the housing 23.

The piston member 82 of the present embodiment has an annular shape when viewed from the axial direction. The piston member 82 includes a large diameter portion 82A and a small diameter portion 82B located on the other side of the large diameter portion 82A in the axial direction. The outer diameter of the small diameter portion 82B in the direction orthogonal to the rotation axis a is smaller than the outer diameter of the large diameter portion 82A. Groove portions extending in the circumferential direction are formed on the outer peripheral surface of the large-diameter portion 82A and the outer peripheral surface of the small-diameter portion 82B, respectively, and sealing members 88 are disposed in these groove portions, respectively. As the sealing member 88, for example, an O-ring can be used. A recess 82C cut out from a surface of the large diameter portion 82A facing one side of the axial direction (a surface facing the cover block 29) facing the other side of the axial direction is provided at one side portion of the piston member 82 in the axial direction. The recess 82C accommodates at least a part of the pressing member 84. In a state where the piston member 82 is assembled to the housing 23 (fixed block 25), a pressure chamber C is formed between a step portion formed between the large diameter portion 82A and the small diameter portion 82B and the fixed block 25. The piston member 82 is configured to be relatively movable in the axial direction with respect to the fixed block 25. In this case, the volume of the pressure chamber C changes as the piston member 82 moves in the axial direction.

The pressing member 84 is a member for pressing the piston member 82 toward the cylinder-side friction plate 61 and the housing-side plate 71. In the example shown in fig. 1 and 2, the pressing member 84 is constituted by a spring member, particularly a coil spring. The pressing member 84 is disposed between the recess 82C of the piston member 82 and the recess 29C of the cover block 29 in a state compressed in the axial direction. Thus, the pressing member 84 presses the piston member 82 toward the other side in the axial direction.

If the piston member 82 also rotates about the rotation axis a with the rotation of the cylinder 30, the seal member 88 disposed between the piston member 82 and the fixed block 25 may be worn. In this case, the sealing performance of the sealing member 88 is lowered, and when oil flows into the pressure chamber C as described later, the oil may leak out. In order to suppress this oil leakage, the pressing mechanism 80 of the present embodiment includes a regulating member 86 that regulates relative rotation of the piston member 82 with respect to the housing 23 about the rotation axis a. The regulating member 86 can be, for example, a rod-shaped pin member extending in the axial direction. The restricting member 86 is disposed so as to straddle the inside of the cover block-side receiving recess 29D provided to the cover block 29 and the inside of the piston member-side receiving recess 82D provided to the piston member 82. The pressing mechanism 80 has the restricting member 86 to restrict the rotation of the piston member 82 about the rotation axis a, and thus the abrasion of the seal member 88 is suppressed. Therefore, leakage of the oil when the oil flows into the pressure chamber C can be effectively suppressed. Further, the specific shape of the restricting member 86 is not limited to the rod-shaped pin member. For example, the restricting member 86 may be disposed so as to straddle the cover block-side accommodating recess 29D and the piston member-side accommodating recess 82D.

The brake mechanism 60 is used as a brake that exerts a braking force when the operation of the hoist unit is stopped, for example, in the hoist unit in which the hydraulic drive device 10 is incorporated. When oil discharged from an unillustrated hydraulic pump is supplied to the pressure chamber C, the piston member 82 moves to one side in the axial direction against the pressing force of the pressing member 84 toward the other side in the axial direction due to the pressure of the oil in the pressure chamber C. Thereby, the pressing force by the pressing mechanism 80 does not act on the cylinder-side friction plate 61 and the case side plate 71. That is, the cylinder-side friction plate 61 and the housing-side plate 71 are not pressed against each other in the axial direction. In this case, no frictional force is generated between the cylinder side friction plate 61 and the housing side plate 71, and no braking force is generated to reduce the rotation speed of the cylinder 30 or stop the rotation. Therefore, for example, in a winch unit in which the hydraulic drive device 10 is incorporated, operations such as winding up and unwinding can be performed.

When the oil is discharged from the pressure chamber C, the piston member 82 receives the pressing force of the pressing member 84 toward the other side in the axial direction, and moves toward the other side in the axial direction. Thereby, the cylinder-side friction plate 61 and the housing-side plate 71 are pressed against each other in the axial direction. Therefore, a frictional force is generated between the cylinder side friction plate 61 and the housing side plate 71, and a braking force for reducing or stopping the rotation speed of the cylinder 30 is generated. Therefore, for example, in a winch unit in which the hydraulic drive device 10 is incorporated, the operation speed of winding up, unwinding, and the like is reduced or the operation is stopped.

The hydraulic motor 20 of the present embodiment includes a detector 90 that detects the rotation of at least 1 cylinder side friction plate 61. The detector 90 is mounted to the fixed block 25. Specifically, the detector 90 is disposed in a mounting hole 25A provided in the fixed block 25. The detector 90 is located radially outward of the detected portion 69 and is attached so as to face the rotation axis a. As clearly shown in fig. 2 and 3, particularly, the tip (detection portion) of the detector 90 is located close to the detection portion 69 and opposite to the detection portion 69. Further, the proximal end side of the detector 90 is sealed by a sealing member such as an O-ring, and oil leakage through the mounting hole 25A is prevented.

As the detector 90, a proximity sensor capable of detecting the detection target 69 without contacting the detection target 69 is preferably used. In the case where the detection target portion 69 is configured by alternately arranging magnetic poles (N pole and S pole) different from each other on the outer peripheral surface of the main body 63A in the circumferential direction, for example, a proximity sensor that can detect a change in magnetic field or the like generated when the magnetic poles different from each other included in the detection target portion 69 pass near the tip of the detector 90 can be used as the detector 90. In the case where the detection target portion 69 is configured such that the convex portions and the concave portions are alternately arranged on the outer peripheral surface of the main body 63A in the circumferential direction, the detector 90 can use a proximity sensor capable of detecting, for example, a change in impedance due to a change in eddy current generated in the detection target portion 69 by a magnetic field generated in the detector 90 when the convex portions and the concave portions included in the detection target portion 69 pass near the distal end of the detector 90, a change in electrostatic capacitance generated between the detection target portion 69 and the detector 90, or the like.

The hydraulic motor 20 of the present embodiment includes: a housing 23; a cylinder 30 which is housed in the case 23 and is rotatable; a cylinder block side friction plate 61 whose rotation relative to the cylinder block 30 about the rotation axis a of the cylinder block 30 is restricted; a housing side plate 71 whose rotation relative to the housing 23 is restricted, the housing side plate 71 at least partially overlapping the cylinder-side friction plate 61 in the rotational axis direction; a pressing mechanism 80 that presses the cylinder-side friction plate 61 and the housing-side plate 71 against each other in the rotational axis direction; and a detector 90 fixed to the housing 23 and detecting rotation of at least 1 of the cylinder-side friction plates 61.

According to the hydraulic motor 20, in the hydraulic motor 20 including the brake mechanism 60 including the cylinder side friction plate 61, the housing side plate 71, and the pressing mechanism 80, the rotation speed of the hydraulic motor 20 can be measured by measuring the rotation of the cylinder side friction plate 61 relatively distant from the rotation axis a without directly measuring the rotation of the rotary shaft 21 and the cylinder 30. Therefore, in the downsized hydraulic motor 20, the degree of freedom of the arrangement position of the detector 90 can be improved, and the rotation speed of the hydraulic motor 20 can be appropriately measured.

The hydraulic motor 20 of the present embodiment includes a plurality of cylinder side friction plates 61, and the detector 90 detects rotation of the cylinder side friction plate 61A closest to the pressing mechanism 80 in the direction along the rotation axis a among the plurality of cylinder side friction plates 61.

From the viewpoint of ensuring appropriate braking capability in the brake mechanism 60, it is preferable that the outer diameter of the main body 63 of the cylinder side friction plate 61 on which the detection section 69 is provided is equal to the outer diameter of the main body 63 of the other cylinder side friction plate 61. In this case, the outer diameter of the cylinder side friction plate 61 on which the detected portion 69 is provided is larger than the outer diameter of the other cylinder side friction plate 61 by the thickness of the detected portion 69 along the radial direction. In the hydraulic motor 20 of the present embodiment, the cylinder side friction plate 61, which has the largest possible radial dimension among the plurality of cylinder side friction plates 61 and on which the detected portion 69 is provided, is disposed at a position closest to the pressing mechanism 80, that is, at a position closest to the opening portion of the fixed block 25 on the cover block 29 side. Therefore, when the plurality of cylinder side friction plates 61 are incorporated into the fixed block 25, the cylinder side friction plates 61 provided with the detection target portions 69 can be finally assembled, and the assembly work can be facilitated.

In the hydraulic motor 20 of the present embodiment, the thickness of the cylinder side friction plate 61A closest to the pressing mechanism 80 is larger than the thickness of the other cylinder side friction plates 61.

According to the hydraulic motor 20, the area of the portion of the detection target 69 facing the detector 90 can be increased. This can effectively improve the accuracy of detecting the rotation of the cylinder side friction plate 61A by the detector 90.

In the hydraulic motor 20 of the present embodiment, the pressing mechanism 80 includes: a piston member 82 that transmits a pressing force to the cylinder side friction plate 61 and the housing side plate 71; and a restricting member 86 that restricts rotation of the piston member 82 about the rotation axis a.

According to the hydraulic motor 20, the pressing mechanism 80 includes the regulating member 86, and the rotation of the piston member 82 about the rotation axis a is regulated, and the abrasion of the seal member 88 disposed between the outer peripheral portion of the piston member 82 and the fixed block 25 can be suppressed. Therefore, leakage of oil when the oil flows into the pressure chamber C formed between the piston member 82 and the fixed block 25 can be effectively suppressed.

While the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made in the above embodiments.

Claims

1. A hydraulic motor includes:

a housing;

a cylinder housed in the housing and rotatable;

2. The hydraulic motor of claim 1,

the hydraulic motor has a plurality of cylinder-side friction plates,

3. The hydraulic motor of claim 2,

4. The hydraulic motor according to any one of claims 1 to 3,

the pressing mechanism includes: