CN111577524B

CN111577524B - hydraulic motor

Info

Publication number: CN111577524B
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: 2023-10-20
Anticipated expiration: 2040-02-17
Also published as: JP7281918B2; JP2020133474A; CN111577524A; KR20200100534A

Abstract

The invention provides a hydraulic motor which can properly measure the rotation speed while seeking miniaturization. The hydraulic motor (20) is provided with: a housing (23); a cylinder (30) housed in the housing (23) and rotatable; a cylinder-side friction plate (61) which is restricted in rotation relative to the cylinder (30) about the rotation axis (A) of the cylinder (30); a case side plate (71) which is restricted from rotating relative to the case (23), wherein the case side plate (71) and the cylinder side friction plate (61) are at least partially overlapped in the rotation 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 rotation axis direction; and a detector (90) fixed to the housing (23) and detecting rotation of at least 1 cylinder-side friction plate (61).

Description

Hydraulic motor

Technical Field

The present invention relates to a hydraulic motor used for a construction vehicle or 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 has: a cylinder block formed with a plurality of cylinder bores extending in the rotation 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 the pistons in the cylinder bores.

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

However, in the case of further miniaturizing the hydraulic motor, it is considered that the rotation sensor interferes with any one of the components disposed in the hydraulic motor. In this case, it is difficult to appropriately arrange the rotation sensor in the hydraulic motor.

Disclosure of Invention

The present invention has been made in consideration of such a point, and an object thereof is to provide a hydraulic motor capable of properly measuring a rotational speed while achieving downsizing.

The hydraulic motor of the present invention is provided with:

a housing;

a cylinder which is housed in the housing and is rotatable;

a cylinder-side friction plate that is restricted in rotation relative to the cylinder about a rotation axis of the cylinder;

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

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

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

In the hydraulic motor of the present invention, it may be,

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

the detector detects rotation of the cylinder-side friction plate 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 may be,

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

In the hydraulic motor of the present invention, it may be,

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 restricting member that restricts 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 appropriately measure the rotational speed while achieving downsizing.

Drawings

Fig. 1 is a view for explaining an embodiment of the present invention, and is a view showing a cross section of a hydraulic drive device incorporating a hydraulic motor.

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

Fig. 3 is a view showing a cross section corresponding to 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 rotation shaft; 23. a housing; 25. a fixed block; 25A, mounting holes; 27. a rotating block; 29. a cover block; 30. a cylinder; 32. a cylinder hole; 34. a concave portion; 40. a piston; 50. a sloping plate; 60. a braking mechanism; 61. a cylinder side friction plate; 63. a main body; 65. a convex portion; 67. a lining; 69. a detection unit; 71. a housing side plate; 80. a pushing mechanism; 82. a piston member; 84. a pressing member; 86. a restriction member; 88. a sealing member; 90. a detector; A. an axis of rotation; C. a pressure chamber.

Detailed Description

An embodiment of the present invention will be described below with reference to the drawings. In the drawings attached to the present specification, for convenience of illustration and easy understanding, the scale, aspect ratio, and the like are appropriately changed and exaggerated with respect to the size of the object, and the like.

The terms such as "parallel", "orthogonal", "identical", and the like, length, angle, and the like used in the present specification, the terms such as shape and geometry, and the terms such as determining the degree of the terms are not limited to strict meanings, and are interpreted to include a range of degrees in 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 view showing a cross section of a hydraulic drive device 10 incorporating a hydraulic motor 20, fig. 2 is a view showing a part with II of fig. 1 in an enlarged manner, and fig. 3 is a view showing a cross section corresponding to a line III-III of fig. 1. The hydraulic drive device 10 of the present embodiment is used for driving a hoist unit provided in a work vehicle as an example of a work machine, and the use of the hydraulic drive device 10 is not limited to this, and may be used for driving a traveling unit and 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 assembled to the hydraulic motor 20. In fig. 1, a part of the hydraulic motor 20 and the back pressure valve 12 are shown in 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 rotary shaft 21 or a direction parallel to the direction extending along the rotation axis a. In the following description, the direction refers to the axial direction of the rotary shaft 21 in the case of simply referred to as the axial direction. The direction perpendicular to the rotation axis a is referred to as a radial direction, and the 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 the purpose of driving the hydraulic motor 20 to supply and discharge the hydraulic oil, and 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 or the inertia of the load and the self weight after the supply of the hydraulic oil to the hydraulic motor 20 is stopped.

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

When one of the external communication port of the 1 st supply/discharge line and the external communication port of the 2 nd supply/discharge line is connected to the hydraulic pump in accordance with the 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/discharge line is connected to the hydraulic pump, the internal communication port of the 1 st supply/discharge line is connected to the hydraulic motor 20 to supply the hydraulic oil. On the other hand, when the external communication port of the 2 nd supply/discharge line is in communication with the hydraulic pump, the internal communication port of the 2 nd supply/discharge line is connected to the hydraulic motor 20 to supply the hydraulic oil. In this case, in the former case, the hoist unit is wound up, and in the latter case, the hoist unit is unwound.

Next, the hydraulic motor 20 will be described. In the present embodiment, the hydraulic motor 20 is a decelerator-equipped hydraulic motor including a decelerator 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 deceleration mechanism not shown. Further, the hydraulic motor 20 is not limited thereto, and may be a hydraulic motor that does not include a decelerator.

The housing 23 has: a fixed block 25; a rotating block 27 mounted to the fixed block 25; and a cover block 29 mounted with respect to the fixed block 25 from a side opposite to the rotating block 27. The rotation block 27 is configured to be rotatable relative to the fixed block 25 about a rotation axis a of the rotation shaft 21. The cover block 29 is fixed with respect to the fixed block 25. The housing 23 houses the rotation 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 reduction mechanism.

The rotation 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 (right side in fig. 1) in the axial direction. A receiving hole 29A is formed in a surface of the cover block 29 facing the fixed block 25. One end of the rotation shaft 21 in the axial direction is accommodated in the accommodation hole 29A. A 1 st bearing 29B is disposed between the accommodation hole 29A and the rotation shaft 21. Thus, one end portion of the rotation shaft 21 in the axial direction is supported in the receiving hole 29A by the 1 st bearing 29B so as to be rotatable about the rotation axis a. Further, although not shown, the rotary shaft 21 is rotatably supported by the fixed block 25 via another bearing in the fixed block 25. A recess 29C cut away from the other side surface (surface facing the fixed block 25 side) of the cover block 29 in the axial direction toward one side in the axial direction is provided in the other side portion of the cover block 29 in the axial direction. The recess 29C accommodates at least a portion of the pressing member 84 of the pressing 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 block 30 is held to the rotary shaft 21 by a spline coupling. Thereby, the relative movement of the cylinder 30 with respect to the circumferential direction of the rotary shaft 21 is restricted. In other words, the cylinder 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 radial outside of the rotary shaft 21 when viewed in the axial direction. The cylinder block 30 has a plurality of cylinder bores 32 extending in the axial direction. The plurality of cylinder bores 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 peripheral 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 in which the cylinder 30 is cut out 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 of the cylinder bores 32 and circumferentially between two adjacent cylinder bores 32. That is, the number of cylinder bores 32 provided in the cylinder block 30 is the same as the number of recesses 34. The plurality of concave portions 34 are arranged with a constant angular pitch along the circumferential direction. The concave portion 34 engages with a convex portion 65, which will be described later, provided on 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 circumferential direction of the cylinder 30.

The pistons 40 are held in the plurality of cylinder bores 32, respectively, and are movable in the axial direction. By supplying the hydraulic oil flowing from the hydraulic pump via the back pressure valve 12 from the cover block 29 side to the cylinder bore 32, the pistons 40 move toward the swash plate 50 side, respectively. The pistons 40 are pushed by inclined surfaces 51 of the swash plate 50, which will be described later, and move toward the cover block 29, and the hydraulic oil in the cylinder bores 32 is discharged. A shoe 41 is attached to each end of each piston 40 on the swash plate 50 side so as to be swingable. The shoes 41 move along the inclined surface 51 of the swash plate 50 on the inclined surface 51.

The swash plate 50 has a slope 51 on the cylinder block 30 side for rotationally moving the pistons 40 in the circumferential direction. The inclined surface 51 is inclined with respect to a plane orthogonal to the rotation axis a. The piston 40 is in contact with the inclined surface 51 via the shoe 41. Further, the swash plate 50 is formed with a through hole 53 through which the rotary shaft 21 passes. When the piston 40 moves toward the swash plate 50, the inclined surface 51 applies a reaction force to the piston 40 in the circumferential direction. Accordingly, when the hydraulic oil is supplied to the cylinder hole 32 and the corresponding piston 40 advances from the cylinder hole 32, the piston 40 rotates and moves in the circumferential direction, and the cylinder 30 and the rotary shaft 21 rotate integrally with each other.

The other end (right side in fig. 1) of the rotation shaft 21 in the axial direction is connected to a reduction mechanism (not shown). As an example, the reduction mechanism includes a planetary gear reduction mechanism, and reduces the rotation of the rotation shaft 21 to transmit the rotation to the rotation block 27. The rotation block 27 is rotatably supported by the fixed block 25, and rotates about the rotation axis a when rotation is transmitted from the rotation shaft 21 via the reduction mechanism. An annular flange portion 27A extending radially outward is formed on the rotating block 27, and a drum, not shown, is mounted on the flange portion 27A. The drum rotates with the rotation of the rotation block 27, and a hoist unit or the like, not shown, is 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 in 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-like member having a plate surface orthogonal to the rotation axis a and having an annular shape as viewed from the axial direction. The brake mechanism 60 of the present embodiment has a plurality of cylinder-side friction plates 61 aligned in the axial direction. Each cylinder-side friction plate 61 has a main body 63 and a lining 67 provided on one and the other sides 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 inward in the radial direction 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 projections 65 arranged in the circumferential direction in the inner peripheral portion. The plurality of convex portions 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 protruding portion 65 is located in the recessed portion 34. In particular, at least a portion of the convex portion 65 including the tip portion located radially inward is located within the concave portion 34. Thereby, the protrusion 65 engages with the recess 34, and the movement of the cylinder-side friction plate 61 relative to the circumferential direction of the cylinder 30 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 cylinder side friction plate 61 of the plurality of cylinder side friction plates 61 is provided with a detected portion 69. In the present embodiment, the detected portion 69 is provided on the cylinder side friction plate 61A (located at the most-lateral position in the axial direction) of the plurality of cylinder side friction plates 61, which 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 detected portion 69 is provided at the outer peripheral portion of the main body 63A. The detection unit 69 is provided to detect the rotation of the cylinder side friction plate 61A by the detector 90. The specific configuration of the detected portion 69 is not particularly limited as long as it can be detected by the detector 90. As an example, the detected portion 69 may be configured by alternately disposing mutually different magnetic poles (N pole and S pole) on the outer peripheral surface of the main body 63A in the circumferential direction. In other words, the detected portion 69 may be configured to include mutually different magnetic poles alternately arranged in the circumferential direction. As another example, the detected portion 69 may be configured by alternately disposing convex portions and concave portions on the outer peripheral surface of the main body 63A in the circumferential direction. In other words, the detected portion 69 can be configured as a detected portion including convex portions and concave portions alternately arranged in the circumferential direction.

The case side plate 71 is a plate-like member having a plate surface orthogonal to the rotation axis a and having an annular shape as viewed from the axial direction. The brake mechanism 60 of the present embodiment has a plurality of casing side plates 71 aligned in the axial direction. The cylinder-side friction plates 61 and the case side plates 71 are alternately arranged along the axis direction, and the case side plates 71 and the cylinder-side friction plates 61 are at least partially overlapped in the rotation 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 casing side plates 71.

The relative rotation of the housing side plate 71 with respect to the housing 23 (the 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 projections are provided on the outer peripheral portion of the case side plate 71, and the projections are arranged in the circumferential direction. Further, recesses corresponding to the respective convex portions are formed in the fixing block 25 of the housing 23. The concave portion is formed as a groove portion extending in the axial direction. Further, the protruding portions of the case side plates 71 engage with the recessed portions of the fixing blocks 25, whereby the relative rotation of the case side plates 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 casing side plate 71; a restricting member 86 restricting relative rotation of the piston member 82 with respect to the housing 23 about the rotation axis a; 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 a ring-like shape as 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 small diameter portion 82B has a smaller outer diameter than the large diameter portion 82A in a direction orthogonal to the rotation axis a. Grooves extending in the circumferential direction are formed in the outer peripheral surface of the large diameter portion 82A and the outer peripheral surface of the small diameter portion 82B, respectively, and the seal members 88 are disposed in the grooves, respectively. As the sealing member 88, for example, an O-ring seal can be used. A recess 82C cut away from a surface of the large diameter portion 82A on one side in the axial direction (a surface facing the cover piece 29 side) toward the other side in the axial direction is provided at one side portion in the axial direction of the piston member 82. The recess 82C accommodates at least a portion of the pressing member 84. In a state where the piston member 82 is assembled to the housing 23 (the fixed block 25), a pressure chamber C is formed between a stepped 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, as the piston member 82 moves in the axial direction, the volume of the pressure chamber C changes.

The pressing member 84 is a member for pressing the piston member 82 toward the cylinder-side friction plate 61 and the case side plate 71. In the example shown in fig. 1 and 2, the pressing member 84 is constituted by a spring member, in particular, 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 around 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 sealability of the seal member 88 is lowered, and when oil flows into the pressure chamber C as will be described later, leakage of the oil may occur. In order to suppress the leakage of the oil, the pressing mechanism 80 of the present embodiment has a restricting member 86 that restricts the relative rotation of the piston member 82 with respect to the housing 23 about the rotation axis a. The restricting member 86 may be a bar-shaped pin member extending in the axial direction, for example. The restricting member 86 is disposed in a crossing manner in the cover piece side accommodation recess 29D provided to the cover piece 29 and in the piston member side accommodation recess 82D provided to the piston member 82. By having such a restricting member 86, the pressing mechanism 80 restricts the rotation of the piston member 82 about the rotation axis a, and wear of the seal member 88 is suppressed. Thus, leakage of oil when the oil flows into the pressure chamber C can be effectively suppressed. The specific shape of the restricting member 86 is not limited to a rod-shaped pin member. For example, the restricting member 86 may be disposed so as to extend across the cover piece side accommodating recess 29D and the piston member side accommodating recess 82D.

The brake mechanism 60 is used as a brake that generates 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 a hydraulic pump, not shown, 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 to the other side in the axial direction due to the pressure of the oil in the pressure chamber C. Thus, the pressing force by the pressing mechanism 80 does not act on the cylinder-side friction plate 61 and the housing side plate 71. That is, the cylinder-side friction plate 61 and the case side plate 71 are not pressed against each other in the axial direction. In this case, no friction 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. Thus, for example, the winding machine unit incorporating the hydraulic drive device 10 can perform winding and unwinding operations.

When the oil is discharged from the pressure chamber C, the piston member 82 moves to the other side in the axial direction by receiving the pressing force of the pressing member 84 to the other side in the axial direction. Thereby, the cylinder-side friction plate 61 and the case side plate 71 are pressed against each other in the axial direction. Accordingly, friction is generated between the cylinder-side friction plate 61 and the housing side plate 71, and a braking force is generated to reduce the rotation speed of the cylinder 30 or stop the rotation. Thus, for example, in a hoist unit incorporating the hydraulic drive device 10, 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 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 the mounting hole 25A provided to the fixed block 25. The detector 90 is located radially outward of the detected portion 69, and is mounted so as to face the rotation axis a. As clearly shown in fig. 2 and 3, in particular, the tip (detection portion) of the detector 90 is located close to the detected portion 69 and opposite to the detected portion 69. The base end side of the detector 90 is sealed with 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 portion 69 so as not to contact the detection target portion 69 is preferably used. When the detection unit 69 is configured by alternately disposing mutually different magnetic poles (N-pole and S-pole) on the outer peripheral surface of the main body 63A in the circumferential direction, the detector 90 can use, for example, a proximity sensor that can detect a change in magnetic field or the like generated when the mutually different magnetic poles included in the detection unit 69 pass near the tip of the detector 90. In addition, in the case where the detection target portion 69 is configured by alternately disposing the convex portions and the concave portions 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 due to a magnetic field generated at the detector 90 when the convex portions and the concave portions included in the detection target portion 69 pass near the tip of the detector 90, a change in electrostatic capacitance generated between the detection target portion 69 and the detector 90, and the like.

The hydraulic motor 20 of the present embodiment includes: a housing 23; a cylinder 30 housed in the housing 23 and rotatable; a cylinder-side friction plate 61 whose rotation about the rotation axis a of the cylinder 30 with respect to the cylinder 30 is restricted; a housing side plate 71 whose rotation with respect to the housing 23 is restricted, the housing side plate 71 and the cylinder side friction plate 61 being at least partially overlapped in the rotation 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 rotation axis direction; and a detector 90 fixed to the housing 23 and detecting rotation of at least 1 cylinder-side friction plate 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 of the rotary shaft 21 and the cylinder 30 is not directly measured, and the rotation of the cylinder side friction plate 61 relatively far from the rotation axis a is measured, so that the rotation speed of the hydraulic motor 20 can be measured. Accordingly, in the miniaturized hydraulic motor 20, the degree of freedom in the arrangement position of the detector 90 can be increased, and the rotational speed of the hydraulic motor 20 can be appropriately measured.

The hydraulic motor 20 of the present embodiment has 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 proper braking ability in the brake mechanism 60, it is preferable that the outer diameter of the main body 63 of the cylinder side friction plate 61 provided with the detected portion 69 is set to be 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 provided with the detection target portion 69 is larger than the outer diameters of the other cylinder side friction plates 61 by the thickness of the detection target portion 69 in the radial direction. In the hydraulic motor 20 of the present embodiment, the cylinder side friction plate 61 provided with the detection target portion 69, which is the largest in the radial dimension of the plurality of cylinder side friction plates 61, is disposed at a position closest to the pressing mechanism 80, that is, at a position closest to the opening portion on the cover block 29 side in the fixed block 25. Therefore, when the plurality of cylinder side friction plates 61 are fitted into the fixed block 25, the cylinder side friction plates 61 provided with the detection portion 69 can be assembled last, and the assembling 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 detected portion 69 facing the detector 90 can be increased. This effectively improves the detection accuracy of 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 restricting member 86, and the rotation of the piston member 82 about the rotation axis a is restricted, so that the abrasion of the sealing member 88 disposed between the outer peripheral portion of the piston member 82 and the fixed block 25 can be suppressed. Thus, the oil can be effectively prevented from leaking out when the oil flows into the pressure chamber C formed between the piston member 82 and the fixed block 25.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications are possible in the above embodiments.

Claims

1. A hydraulic motor is provided with:

a housing;

a cylinder which is housed in the housing and is rotatable;

and a detector fixed to the housing and detecting rotation of at least 1 cylinder-side friction plate from the outside in a direction orthogonal to the rotation axis direction.

2. The hydraulic motor according to claim 1, wherein,

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

3. The hydraulic motor according to claim 2, wherein,

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

the pressing mechanism includes: