Hydraulic motor

Abstract

A hydraulic motor 1 comprises: a casing 10; a drive shaft 20 which is rotatably supported by the casing 10; a brake disk 90 which is disposed in an outer circumferential area of the drive shaft 20 in a state where relative rotation with the drive shaft 20 is restricted; a separate plate 91 which is disposed at a position adjacent to the brake disk 90 in the axial direction of the drive shaft 20 in a state where relative rotation with the casing 10 is restricted; a brake piston 92 which is disposed alongside the brake disk 90 and the separate plate 91 in the axial direction so as to be movable in the axial direction of the drive shaft 20; a brake spring 94 which biases the brake piston 92 such that the brake piston 92 presses the brake disk 90 and the separate plate 91; and a first oil chamber P1 which, when oil is introduced, generates hydraulic pressure for biasing the brake piston 92 in the same direction as the biasing direction of the brake spring 94.

Description

Hydraulic motor

[0001] This disclosure relates to a hydraulic motor.

[0002] The brake device of the hydraulic motor is located in a housing space provided inside the casing at a position corresponding to the outer circumference of the end of the drive shaft (see, for example, Patent Document 1). The brake device comprises a plurality of brake discs and a plurality of separate plates. The brake discs and separate plates are arranged alternately along the axial direction such that the separate plates are located at both ends in the axial direction. The brake discs are slidable along the axis of the drive shaft, and their rotation relative to the drive shaft is restricted. The separate plates are slidable along the axis of the drive shaft, and their rotation relative to the casing is restricted.

[0003] The brake disc and separator plate are positioned with a brake piston facing the separator plate at one axial end and a brake restricting plate facing the separator plate at the other end. The brake piston is slidably positioned along the axis of the drive shaft. Under normal conditions, the brake piston is pressed toward the separator plate at one axial end by a brake spring interposed between it and the casing. When hydraulic pressure is applied to the brake piston, the brake piston moves away from the separator plate at one axial end against the pressure of the brake spring. The brake restricting plate is interposed between the casing and the separator plate at the other axial end. The brake restricting plate restricts the movement of the brake disc and separator plate when the brake piston is pressed toward the separator plate at one axial end, and applies a frictional force between the brake disc and the separator plate.

[0004] In the hydraulic motor configured as described above, if the pressing force by the brake piston is removed, relative rotation of the brake disk and the separate plate is allowed. Thereby, rotation of the drive shaft with respect to the casing becomes possible. On the other hand, when the brake disk and the separate plate are pressed against the brake regulating plate via the brake piston, a frictional force acts between them, and relative rotation between the brake disk and the separate plate is restricted. Thereby, rotation of the drive shaft with respect to the casing is restricted.

[0005] Japanese Unexamined Patent Application Publication No. 2013-227879

[0006] Since the brake disk and the drive shaft rotate synchronously, torque cross is generated by stirring the hydraulic oil.

[0007] An object of the present disclosure is to provide a hydraulic motor with reduced torque cross.

[0008] According to the present disclosure, there is provided a hydraulic motor including: a casing; a rotating shaft rotatably supported by the casing; a first member disposed in an outer peripheral region of the rotating shaft in a state where relative rotation with the rotating shaft is restricted; a second member disposed adjacent to the first member in an axial direction of the rotating shaft in a state where relative rotation with the casing is restricted; a third member movably in the axial direction of the rotating shaft and disposed side by side with the first member and the second member in the axial direction; a spring that biases the third member so that the third member presses the first member and the second member; and a first oil chamber that generates a hydraulic pressure that biases the third member in the same direction as the biasing direction of the spring when oil is introduced.

[0009] According to the present disclosure, a hydraulic motor with reduced torque cross can be provided.

[0010] Figure 1 is a cross-sectional side view of the hydraulic motor of the first embodiment. Figure 2 is a cross-sectional plan view of the hydraulic motor shown in Figure 1. Figure 3 is a diagram showing a brake disc applied to the hydraulic motor of Figure 1. Figure 4 is a diagram showing a separate plate applied to the hydraulic motor of Figure 1. Figure 5 is a cross-sectional plan view of the auxiliary member, first oil chamber and second oil chamber of the first embodiment. Figure 6 is a cross-sectional plan view of the auxiliary member, first oil chamber and second oil chamber of the first embodiment. Figure 7 is a cross-sectional plan view of the auxiliary member, first oil chamber and second oil chamber of the second embodiment. Figure 8 is a cross-sectional plan view of the auxiliary member, first oil chamber and second oil chamber of the third embodiment.

[0011] The embodiments described below will be explained with reference to the drawings, but the disclosure is not limited thereto. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0012] [First Embodiment] <Hydraulic Motor> Figure 1 is a cross-sectional side view of the hydraulic motor of the first embodiment. Figure 2 is a cross-sectional plan view of the hydraulic motor shown in Figure 1. The hydraulic motor 1 is an oblique-axis axial piston motor. The hydraulic motor 1 is a hydraulic motor for driving vehicles used as construction machinery such as bulldozers and hydraulic excavators. The hydraulic motor 1 includes a casing 10 that houses various components of the hydraulic motor 1.

[0013] The casing 10 comprises a casing body 11 and an end cover 12. The casing body 11 is cylindrical with one end in the axial direction open. The casing body 11 is hollow, having a hollow interior 11a. The hollow interior 11a is filled with oil. The hollow interior 11a comprises a storage space 11b, a storage space 11d, and a storage space 11e. Storage spaces 11b, 11d, and 11e are in communication with each other.

[0014] The housing space 11b accommodates a plurality of brake discs (first members) 90 and a plurality of separate plates (second members) 91, which will be described later. The housing space 11b is an annular hole located at a position that is the outer circumference of the disc portion 23 of the drive shaft 20, which will be described later. The housing space 11b is located adjacent to the roller housing portion 42b of the second tapered roller bearing 42, which will be described later.

[0015] The housing space 11d houses the first tapered roller bearing 41, which will be described later.

[0016] The housing space 11e houses the second tapered roller bearing 42, which will be described later.

[0017] Multiple arc-shaped grooves (not shown) are arranged on the inner circumferential surface of the casing body 11 facing the housing space 11b. The arc-shaped grooves are recesses for engaging with the arc-shaped projections 91a of the separate plate 91, which will be described later. Multiple arc-shaped grooves are arranged at equal intervals from each other, opening toward the housing space 11b.

[0018] As shown in Figure 2, a pair of connecting passages 11f are provided that connect the storage spaces 11b, 11d, and 11e. In this embodiment, the pair of connecting passages 11f are positioned 180° apart from each other.

[0019] The end cover 12 closes the opening of the casing body 11. The end cover 12 is located at one end of the casing body 11 in the axial direction.

[0020] The casing 10 houses the drive shaft (rotating shaft) 20 and the cylinder block 30 within the hollow interior 11a of the casing body 11.

[0021] The drive shaft 20 comprises a first bearing support portion 21, a second bearing support portion 22, and a disc portion 23. The first bearing support portion 21, the second bearing support portion 22, and the disc portion 23 are integrally formed. The first bearing support portion 21 is cylindrical. The second bearing support portion 22 is positioned at one axial end of the first bearing support portion 21. The second bearing support portion 22 is cylindrical with a larger diameter than the first bearing support portion 21. The disc portion 23 is positioned at one axial end of the second bearing support portion 22. The disc portion 23 is disc-shaped with a larger diameter than the second bearing support portion 22.

[0022] The drive shaft 20 is rotatably supported around its axis 20C relative to the casing body 11 of the casing 10 via a first bearing support portion 21 and a second bearing support portion 22. A first tapered roller bearing 41 is positioned between the first bearing support portion 21 and the casing body 11. A second tapered roller bearing 42 is positioned between the second bearing support portion 22 and the casing body 11. The second tapered roller bearing 42 has a larger diameter than the first tapered roller bearing 41. The second tapered roller bearing 42 is interposed between the drive shaft 20 and the casing body 11 with the larger diameter portion of the tapered roller 42a facing one end of the casing body 11 in the axial direction.

[0023] The disc portion 23 slidably supports a plurality of piston rods 40 and a center shaft 50. A plurality of rod support portions 23a and shaft support portions 23b are arranged on one axial end face of the disc portion 23. The rod support portions 23a and shaft support portions 23b are each substantially hemispherical recesses formed on one axial end face of the disc portion 23. The rod support portions 23a support the piston rods 40. In an axial view, the rod support portions 23a are arranged at equal intervals from each other on a common circumference centered on the axis 20C of the drive shaft 20. The shaft support portions 23b support the center shaft 50. The shaft support portions 23b are located on the axis 20C of the drive shaft 20 in the disc portion 23. A relief passage 24 is connected to the shaft support portions 23b.

[0024] The relief passage 24 is a passage for releasing oil from the oil passage located in the inner shaft 51, which will be described later. The relief passage 24 extends from the shaft support portion 23b along the axis 20C of the drive shaft 20 to the other axial direction, and then extends radially outward as it moves toward the other axial direction. The relief passage 24 opens onto the outer circumferential surface of the drive shaft 20 between the first bearing support portion 21 and the second bearing support portion 22.

[0025] A spline 25 is arranged on the outer circumferential surface of the disc portion 23 that faces the housing space 11b. The spline 25 engages with the spline groove 90a of the brake disc 90, which will be described later. The spline 25 is formed on the outer circumferential surface of the disc portion 23 at a position opposite to the portion of the casing 10 that forms the arc-shaped groove.

[0026] The piston rod 40 is tapered, with its outer diameter increasing from the base to the tip. The base of the piston rod 40 is one side in the axial direction, and the tip is the other side. The piston rod 40 comprises a support ball head 40a located at the base and a piston portion 40b located at the tip. The support ball head 40a is spherical. The support ball head 40a is slidably inserted into the rod support portion 23a of the disc portion 23 of the drive shaft 20. The support ball head 40a has an outer diameter larger than the outer diameter of the piston portion 40b.

[0027] The center shaft 50 comprises an inner shaft 51 and an outer race 52. The inner shaft 51 comprises a shaft base 51a and a shaft support ball head 51b. The shaft base 51a is cylindrical. The shaft support ball head 51b is located at the base end of the shaft base 51a. The base end of the shaft support ball head 51b is one side in the axial direction of the shaft support ball head 51b. The shaft support ball head 51b is spherical. The shaft support ball head 51b is slidably inserted into a shaft support portion 23b formed on the disc portion 23 of the drive shaft 20. The outer diameter of the shaft base 51a is smaller than the outer diameter of the shaft support ball head 51b. Inside the inner shaft 51, an oil passage is located between one end face in the axial direction of the shaft base 51a and the top of the shaft support ball head 51b.

[0028] The outer race 52 is cylindrical. The outer race 52 has a shaft housing hole 52a and a spring housing hole 52b on its axis 30C. The shaft housing hole 52a is a cylindrical hole that opens to the other axial end face of the outer race 52. The shaft housing hole 52a has a circular cross-section along its radial direction. The inner diameter of the shaft housing hole 52a is such that the shaft base 51a of the inner shaft 51 can be fitted in without any looseness. The spring housing hole 52b is a cylindrical hole that opens to the other axial end face of the outer race 52. The spring housing hole 52b has a circular cross-section along its radial direction. The spring housing hole 52b houses a compression spring 53 inside.

[0029] The compression spring 53 is a coil spring. The outer diameter of the compression spring 53 is slightly smaller than the inner diameter of the spring housing hole 52b. The natural length of the compression spring 53 is longer than the spring housing hole 52b.

[0030] After attaching the support ball heads 40a of the multiple piston rods 40 and the shaft support ball heads 51b of the center shaft 50, which are configured in this way, to the rod support portions 23a and shaft support portions 23b formed on the disc portion 23 of the drive shaft 20, the retainer plate 60 is fixed to the end face of the disc portion 23. As a result, the multiple piston rods 40 and the center shaft 50 are supported so as to be able to tilt relative to the end face of the disc portion 23, while restricting the separation movement of each support ball head 40a and shaft support ball head 51b from the end face of the disc portion 23.

[0031] The retainer plate 60 slidably holds a plurality of piston rods 40 and a center shaft 50 supported by the disc portion 23. The retainer plate 60 is a plate-shaped member. The retainer plate 60 has a rod insertion hole 61a and a shaft insertion hole 61b. The rod insertion hole 61a is located in the retainer plate 60 at a position opposite to the rod support portion 23a of the disc portion 23. The shaft insertion hole 61b is located at a position opposite to the shaft support portion 23b. The rod insertion hole 61a is a hole having an inner diameter smaller than the outer diameter of the support ball head 40a of the piston rod 40. The shaft insertion hole 61b is a hole having an inner diameter smaller than the outer diameter of the shaft support ball head 51b of the center shaft 50. The retainer plate 60 is attached to one axial end face of the disc portion 23 with the piston rods 40 already inserted through the rod insertion holes 61a and the center shaft 50 inserted through the shaft insertion hole 61b.

[0032] The cylinder block 30 houses the piston portions 40b of multiple piston rods 40 so that they can reciprocate along the axis 30C, and the center shaft 50 is mounted without play. The cylinder block 30 is a columnar member with a circular cross-section along the radial direction. The cylinder block 30 comprises multiple cylinder bores 31 and shaft mounting holes 32. The cylinder bores 31 and shaft mounting holes 32 are cylindrical holes formed along the axis 30C of the cylinder block 30. The cylinder bores 31 and shaft mounting holes 32 have a uniform circular cross-section along the radial direction. The cylinder bores 31 and shaft mounting holes 32 open to the other axial end face of the cylinder block 30.

[0033] Multiple cylinder bores 31 are arranged at equal intervals from each other on a common circumference centered on the axis 30C of the cylinder block 30. The circumference on which the cylinder bores 31 are arranged is the same dimension as the circumference on which the rod support portion 23a is located on the disk portion 23 of the drive shaft 20. The piston portion 40b of the piston rod 40 is housed in each cylinder bore 31 so as to be able to reciprocate along the axis 30C.

[0034] The shaft mounting hole 32 is located on the axis 30C of the cylinder block 30. The outer race 52 of the center shaft 50 is mounted in this shaft mounting hole 32 without any play. Since the outer race 52 has a length in the axial direction that is longer than the shaft mounting hole 32, a portion of it protrudes outward from one end face in the axial direction of the cylinder block 30.

[0035] The cylinder block 30 has an axial end face, through which the shaft mounting hole 32 and cylinder bore 31 open, that is a plane perpendicular to the axis 30C, while the other end face is a concave surface 30a. The concave surface 30a of the cylinder block 30 is spherical in shape, with its center located on the extension of the axis 30C of the cylinder block 30. A communication hole 33 and a plurality of connecting passages 34 open in the concave surface 30a of the cylinder block 30.

[0036] The communication hole 33 is a cylindrical hole. The communication hole 33 is located on the axis 30C of the cylinder block 30. The communication hole 33 communicates with the shaft mounting hole 32. The inner diameter of the communication hole 33 is smaller than the inner diameter of the shaft mounting hole 32.

[0037] The connecting passages 34 are openings arranged on the circumference of a circle centered on the axis 30C of the cylinder block 30, and are positioned at equal intervals from one another. The circumference on which the connecting passages 34 are located has a smaller radius than the circumference on which the cylinder bores 31 are located. The connecting passages 34 have an inner diameter smaller than that of the cylinder bores 31. Each connecting passage 34 communicates with an individual cylinder bore 31.

[0038] The cylinder block 30 and the drive shaft 20 are connected by multiple piston rods 40 and a center shaft 50 so that they can slide against each other with their axes intersecting. The cylinder block 30 is capable of rotating around the axis of the center shaft 50, that is, around its own axis 30C.

[0039] A valve plate 70 is positioned between the concave surface 30a of the cylinder block 30 and the end cover 12 of the casing 10. The valve plate 70 comprises a sliding spherical protrusion 71 and a sliding cylindrical protrusion 72. The valve plate 70 slidably abuts against the concave surface 30a of the cylinder block 30 via the sliding spherical protrusion 71, and slidably abuts against the guide surface 12a of the end cover 12 via the sliding cylindrical protrusion 72. The sliding spherical protrusion 71 protrudes spherically with the same radius of curvature as the concave surface 30a of the cylinder block 30. The sliding spherical protrusion 71 is slidable in close contact with the entire surface of the concave surface 30a of the cylinder block 30. The sliding cylindrical protrusion 72 is a convex cylindrical surface that protrudes toward the opposite side from the sliding spherical protrusion 71.

[0040] The guide surface 12a of the end cover 12, which contacts the sliding projection cylindrical surface 72, has the same radius of curvature as the sliding projection cylindrical surface 72. The guide surface 12a of the end cover 12 is a concave cylindrical surface with a longer arc than the sliding projection cylindrical surface 72. The guide surface 12a of the end cover 12 is positioned opposite the disc portion 23 of the drive shaft 20. The position of the guide surface 12a of the end cover 12 is set such that the center point X of the shaft support portion 23b located on the disc portion 23 of the drive shaft 20 is included, and the line perpendicular to the axis 20C of the drive shaft 20 becomes the central axis of the cylinder.

[0041] The valve plate 70 is moved along the guide surface 12a of the end cover 12 by the actuator 80. The actuator 80 has an actuator piston 81, which is an output element, that is tiltably engaged with the valve plate 70 via a linkage pin 82.

[0042] High-pressure ports and low-pressure ports (not shown) are opened on the sliding spherical surface 71 of the valve plate 70 at positions corresponding to the communication passage 34 of the cylinder block 30. The high-pressure ports and low-pressure ports are arranged such that, for example, if the cylinder block 30 is divided into two halves by a virtual plane including the axis 30C of the cylinder block 30 and the axis 20C of the drive shaft 20, the high-pressure ports communicate with a plurality of cylinder bores 31 located on one side, and the low-pressure ports communicate with a plurality of cylinder bores 31 located on the other side.

[0043] Between the sliding protruding spherical surface 71 and the sliding protruding cylindrical surface 72 of the valve plate 70, a communication passage 73 is arranged. The communication passage 73 opens to the sliding protruding spherical surface 71 at a position facing the axis 30C of the cylinder block 30.

[0044] <Brake Device> The hydraulic motor 1 includes a brake device 9 that restricts the rotation of the drive shaft 20. The brake device 9 includes a brake disk 90 and a separate plate 91, a brake piston (third member) 92, a second oil chamber P2, a brake regulating plate 93, a brake spring (spring) 94, an auxiliary member (fourth member) 97, and a first oil chamber P1.

[0045] FIG. 3 is a view showing a brake disk applied to the hydraulic motor of FIG. 1. The brake disk 90 is arranged in the outer peripheral region of the drive shaft 20 in a state where the relative rotation with the drive shaft 20 is restricted. The brake disk 90 is fixed in the circumferential direction to the drive shaft 20 by spline coupling. The brake disk 90 is interposed between the drive shaft 20 and the brake piston 92 and suppresses the rotation of the drive shaft 20 by friction. The brake disk 90 is an annular flat plate. The brake disk 90 has an outer diameter smaller than the inner peripheral surface of the casing 10. The brake disk 90 is arranged slidably along the axis 20C of the drive shaft 20. The brake disk 90 has a spline groove 90a on its inner circumference.

[0046] As shown in FIGS. 1 and 2, the brake disk 90 housed in the housing space 11b meshes with the spline 25 of the drive shaft 20 through the spline groove 90a formed on its inner circumference. Thereby, the brake disk 90 is slidable along the axis 20C with respect to the drive shaft 20, and the relative rotation with the drive shaft 20 is restricted.

[0047] The diameter of the brake disk 90 is set according to the required brake capacity. In the prior art, since the brake capacity can only be adjusted in one step, a brake disk 90 having a diameter suitable for the brake capacity required in an emergency was necessary. In the embodiment, as will be described later, the brake capacity is set in two steps: a first brake operating state used during normal stopping, etc., and a second brake operating state larger than the first brake operating state used during an emergency, etc. For this reason, the diameter of the brake disk 90 can be set smaller than in the prior art.

[0048] FIG. 4 is a view showing a separator plate applied to the hydraulic motor of FIG. 1. The separator plate 91 is an annular flat plate. The separator plate 91 has an inner diameter larger than the spline 25 of the disk portion 23. The separator plate 91 has a plurality of arc-shaped protrusions 91a on its outer periphery.

[0049] The separator plate 91 is arranged at a position adjacent to the brake disk 90 and the drive shaft 20 in the axial direction with its relative rotation with respect to the casing 10 restricted. The separator plate 91 meshes with the arc-shaped groove portion of the casing 10 through the arc-shaped protrusions 91a formed on its outer periphery. Thereby, the separator plate 91 is slidable along the axis 20C of the drive shaft 20 with respect to the casing 10, and its relative rotation with respect to the casing 10 is restricted.

[0050] The brake disk 90 and the separator plate 91 are alternately arranged along the axis 20C of the drive shaft 20 such that the separator plate 91 is at both axial ends.

[0051] The brake pistons 92 and the brake regulating plates 93 are arranged at positions facing each other with the brake disk 90 and the separator plate 91 interposed therebetween. In other words, the brake disk 90 and the separator plate 91 are sandwiched from both ends by the brake pistons 92 and the brake regulating plates 93.

[0052] As shown in Figures 1 and 2, the brake piston 92 is a cylindrical body arranged on the inner surface of the casing body 11 so as to surround the outer circumference of the cylinder block 30. The brake piston 92 is movable in the axial direction of the drive shaft 20 and is arranged alongside the brake disc 90 and the separate plate 91 in the axial direction. The brake piston 92 presses the brake disc 90 and the separate plate 91 in the axial direction of the drive shaft 20, bringing them into contact. The brake piston 92 is slidable along the axis 20C of the drive shaft 20 relative to the casing body 11. The brake piston 92 has a second oil chamber P2 and a first oil chamber P1, which will be described later, between it and the casing 10. The brake piston 92 has a pressing portion 92a at its other axial end and a pair of brake spring chambers 92b at its other end. The brake piston 92 has a pressure-receiving surface (for example, 92d, described later) that faces the first oil chamber P1.

[0053] The second oil chamber P2 is located between the brake piston 92 and the casing 10. When oil is introduced into the second oil chamber P2, it generates hydraulic pressure that biases the brake piston 92 in the opposite direction to the biasing direction of the brake spring 94. The second oil chamber P2 allows the brake piston 92 to slide away from the brake disc 90 by hydraulic pressure. In this embodiment, the second oil chamber P2 allows the brake piston 92 to slide away from the separator plate 91 at one end in the axial direction by hydraulic pressure. The second oil chamber P2 is located between a movable pressure-receiving surface 92c of the brake piston 92 that is aligned perpendicular to the axis 20C of the drive shaft 20 and a fixed pressure-receiving surface 11g of the casing 10 that is positioned opposite the movable pressure-receiving surface 92c of the brake piston 92. The second oil chamber P2 is an annular space. The second oil chamber P2 is connected to the first hydraulic power supply source Q1 (see Figure 6) by a refueling passage (oil channel) 11h (see Figure 6). The refueling passage 11h supplies oil to the second oil chamber P2.

[0054] The pressing portion 92a is a protruding portion configured to face the portion of the separate plate 91 that overlaps with the brake disc 90, which is located in the housing space 11b. The pressing portion 92a can contact the separate plate 91 without contacting the splines 25 of the drive shaft 20 or the casing 10.

[0055] The brake spring chamber 92b is a cylindrical hole formed along the axis 20C of the drive shaft 20. Each brake spring chamber 92b houses a brake spring 94 inside.

[0056] The brake spring 94 biases the brake piston 92. The brake spring 94 biases the brake piston 92 in a direction that presses it against the brake disc 90. In this embodiment, the brake spring 94 biases the brake piston 92 in a direction that presses it against the separate plate 91 at one end in the axial direction. The brake spring 94 is a coil spring interposed between it and the end cover 12. The brake spring 94 is located inside the brake spring chamber 92b in a compressed state. The brake spring 94 functions to maintain a state in which the movable pressure receiving surface 92c and the fixed pressure receiving surface 11g are always in close proximity in the second oil chamber P2.

[0057] The brake restricting plate 93 is a member that restricts the movement of the brake disc 90 and the separate plate 91 toward the second tapered roller bearing 42. The brake restricting plate 93 is an annular thick plate. The brake restricting plate 93 is positioned in the housing space 11b opposite the roller housing portion 42b of the second tapered roller bearing 42. The surface of the brake restricting plate 93 that faces the second tapered roller bearing 42 abuts against the stepped portion 11m formed in the casing body portion 11. The surface of the brake restricting plate 93 that faces the housing space 11b faces the portion of the separate plate 91 that overlaps with the brake disc 90. When the movable pressure-receiving surface 92c of the brake piston 92 and the fixed pressure-receiving surface 11g of the casing 10 are in close proximity, the brake regulating plate 93 maintains a state in which the brake disc 90 and the separate plate 91 are pressed against each other by the pressing force of the brake spring 94 between it and the pressing portion 92a of the brake piston 92.

[0058] Figure 5 is a cross-sectional plan view of the auxiliary member, first oil chamber, and second oil chamber of the first embodiment. Figure 6 is a cross-sectional plan view of the auxiliary member, first oil chamber, and second oil chamber of the first embodiment. The auxiliary member 97 is interposed between the brake piston 92 and the casing 10. The auxiliary member 97 seals the first oil chamber P1. The auxiliary member 97 seals the space between the brake piston 92 and the casing 10. The auxiliary member 97 is fixed to the casing body portion 11 of the casing 10. The auxiliary member 97 does not slide along the axis 20C of the drive shaft 20. The auxiliary member 97 is a cylindrical body arranged on the outer circumference of the axial end of the brake piston 92. The auxiliary member 97 is a cylindrical body arranged on the inner surface of the casing body portion 11 so as to surround the outer circumference of one axial end of the brake piston 92. The auxiliary member 97 has a pressing portion 97a at its other axial end. In the auxiliary member 97, the first oil chamber P1 is positioned between the casing 10 and the pressing portion 97a.

[0059] The first oil chamber P1 is located on the outer circumference of the auxiliary member 97. When oil is introduced into the first oil chamber P1, it generates hydraulic pressure that biases the brake piston 92 in the same direction as the biasing direction of the brake spring 94. The first oil chamber P1 presses the brake disc 90 in a direction that clamps the brake disc 90 between the drive shaft 20 and the brake piston 92 by hydraulic pressure. In this embodiment, the first oil chamber P1 is an annular space. The first oil chamber P1 is located between the pressure-receiving surface (e.g., 92d) of the brake piston 92 and the auxiliary member 97. In this embodiment, the first oil chamber P1 is located between a fixed pressure-receiving surface 97c in the auxiliary member 97 that is aligned in a direction perpendicular to the axis 20C of the drive shaft 20 and a movable pressure-receiving surface 92d in the brake piston 92 that is positioned opposite the auxiliary member 97. In this embodiment, the first oil chamber P1 allows the brake piston 92 to slide in a direction that clamps the brake disc 90 and the separate plate 91 by hydraulic pressure. The first oil chamber P1 is connected to a refueling passage (oil channel) 11i that connects it to the second hydraulic power supply source Q2. The refueling passage 11i supplies oil to the first oil chamber P1.

[0060] <Operation> As shown in Figures 1 and 2, when oil is not supplied from the first hydraulic supply source Q1 and the second hydraulic supply source Q2, and no hydraulic pressure is acting on the second oil chamber P2 and the first oil chamber P1, the pressing force of the brake spring 94 maintains a state in which the movable pressure receiving surface 92c and the fixed pressure receiving surface 11g are in close proximity. This maintains a state in which the brake disc 90 and the separate plate 91 are pressed against each other between the pressing portion 92a of the brake piston 92 and the brake regulating plate 93. In this way, the rotation of the drive shaft 20 relative to the casing 10 is restricted. This state is called the first brake operating state.

[0061] When oil is supplied from the first hydraulic supply source Q1 from the first brake operating state and hydraulic pressure is acting on the second oil chamber P2, the gap between the movable pressure receiving surface 92c and the fixed pressure receiving surface 11g expands against the pressing force of the brake spring 94, and the pressing force between the brake disc 90 and the separate plate 91 is removed. As a result, the brake disc 90 and the separate plate 91 become rotatable relative to each other, in other words, the drive shaft 20 becomes rotatable relative to the casing 10. This state is called the brake release state.

[0062] When the brake is released, oil is supplied to the high-pressure port and the low-pressure port is connected to the oil tank. As a result, the piston rod 40 in the cylinder bore 31 connected to the high-pressure port moves sequentially toward the drive shaft 20, and the piston rod 40 in the cylinder bore 31 connected to the low-pressure port moves sequentially backward, causing the cylinder block 30 to rotate and function as a hydraulic motor 1 with the drive shaft 20 as the output shaft. When the actuator 80 is driven to change the position of the valve plate 70 relative to the guide surface 12a of the end cover 12, the tilt angle of the cylinder block 30 relative to the drive shaft 20 changes, and the amount of stroke travel of the piston rod 40 relative to the cylinder bore 31, i.e., the capacity, is changed and the device operates in that state.

[0063] When oil is not supplied from the first hydraulic supply source Q1, no hydraulic pressure is acting on the second oil chamber P2, and oil is supplied from the second hydraulic supply source Q2, acting on the first oil chamber P1, in addition to the pressing force of the brake spring 94, the pressing force of the brake piston 92 due to the hydraulic pressure in the first oil chamber P1 acts. Specifically, the hydraulic pressure between the fixed pressure receiving surface 97c and the movable pressure receiving surface 92d causes the fixed pressure receiving surface 97c and the movable pressure receiving surface 92d to separate, and the movable pressure receiving surface 92c and the fixed pressure receiving surface 11g come into close proximity with a stronger pressing force than in the first brake operating state. As a result, the brake disc 90 and the separate plate 91 are pressed more strongly against each other between the pressing portion 92a of the brake piston 92 and the brake regulating plate 93 than in the first brake operating state. The rotation of the drive shaft 20 relative to the casing 10 is restricted with a stronger pressing force than in the first brake operating state. This state is called the second brake operating state.

[0064] When the second brake is activated, and oil is supplied from the first hydraulic supply source Q1 while the oil supply from the second hydraulic supply source Q2 is stopped, hydraulic pressure acts on the second oil chamber P2, and the hydraulic pressure in the first oil chamber P1 is removed, eliminating the pressing force acting between the fixed pressure receiving surface 97c and the movable pressure receiving surface 92d. As a result, the state in which the brake disc 90 and the separate plate 91 are pressed against each other between the pressing portion 92a of the brake piston 92 and the brake restricting plate 93 is eliminated. The restriction on the rotation of the drive shaft 20 relative to the casing 10 is released. In this way, the brake is released.

[0065] <Effects> As described above, in this embodiment, the brake spring 94 biases the brake piston 92 in a direction that presses it against the brake disc 90, thereby enabling a first brake operation state. In this embodiment, in addition to the pressing force of the brake spring 94, the hydraulic pressure of the first oil chamber P1 presses the brake disc 90 more strongly than in the first brake operation state, in a direction that clamps the brake disc 90 between the drive shaft 20 and the brake piston 92, thereby enabling a second brake operation state. More specifically, in this embodiment, in addition to the pressing force of the brake spring 94, the hydraulic pressure of the first oil chamber P1 allows the brake piston 92 to slide in a direction that clamps the brake disc 90 and the separate plate 91. According to this embodiment, a first brake operation state and a second brake operation state can be generated. According to this embodiment, the first brake operation state and the second brake operation state can be used interchangeably.

[0066] According to this embodiment, the brake capacity is set to two stages: a first brake operating state and a second brake operating state which is greater than the first brake operating state. According to this embodiment, the diameter of the brake disc 90 can be set to a smaller diameter compared to the conventional technology. According to this embodiment, torque loss in the brake disc 90 can be reduced. According to this embodiment, the fuel efficiency of the hydraulic motor 1 can be improved.

[0067] In contrast, conventional technology only allows for one-step adjustment of brake capacity. Therefore, it was necessary to adjust the brake capacity to match the required capacity in emergencies. This resulted in brake discs with a larger brake capacity than normal, leading to excessive torque loss.

[0068] In this embodiment, torque loss is reduced, and the internal heat generation of the hydraulic motor 1 is reduced. As a result, in this embodiment, it is not necessary to separately introduce cooling fluid for cooling purposes. In this embodiment, by suppressing the flow rate of the hydraulic fluid, the internal pressure of the hydraulic motor case is suppressed, and the cooling mechanism can be made smaller.

[0069] In this embodiment, the cooling flow rate inside the hydraulic motor 1 can be reduced, thereby reducing the rise in internal pressure of the casing 10.

[0070] [Second Embodiment] Figure 7 is a cross-sectional plan view of the auxiliary member, the first oil chamber, and the second oil chamber of the second embodiment. The hydraulic motor 1 illustrated here is, like in the first embodiment, mounted as a hydraulic motor for driving a vehicle used as construction machinery such as a bulldozer or hydraulic excavator. The second embodiment differs from the first embodiment in the auxiliary member (fourth member) 98 and the first oil chamber P1. In the second embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and their detailed descriptions are omitted. The same applies to the following embodiments.

[0071] The auxiliary member 98 is positioned between the brake piston 92 and the casing 10 in the axial direction of the drive shaft 20. The auxiliary member 98 receives hydraulic pressure from the first oil chamber P1 and biases the brake piston 92 in the pressing direction. The auxiliary member 98 is a columnar body positioned at the axial end of the brake piston 92. The auxiliary member 98 is inserted through the brake spring 94. The auxiliary member 98 has a cylindrical body inserted through the brake spring 94 and a head with a larger diameter than the outer diameter of the brake spring 94. The auxiliary member 98 is slidably positioned in the casing 10 along the axis 20C of the drive shaft 20 with its head protruding from the brake spring 94. The auxiliary member 98 has a pressing portion 98a at its other axial end. The first oil chamber P1 is positioned between the end cover 12 of the casing 10 and the head of the auxiliary member 98.

[0072] The first oil chamber P1 is located between the auxiliary member 98 and the casing 10 in the axial direction of the drive shaft 20. The first oil chamber P1 applies hydraulic pressure to the brake piston 92 so that the brake piston 92 is biased in the same direction as the brake spring 94. The first oil chamber P1 is located in the outer peripheral area of ​​the axial end of the auxiliary member 98. In the embodiment, the first oil chamber P1 is located between the outer peripheral portion of the auxiliary member 98 and the end cover 12 of the casing 10. In the embodiment, the first oil chamber P1 is an annular space provided around the auxiliary member 98. In the embodiment, the first oil chamber P1 presses the auxiliary member 98 with hydraulic pressure, making the brake piston 92 slidable in the direction of clamping the brake disc 90 and the separate plate 91. The first oil chamber P1 is connected to a second hydraulic pressure supply source Q2 by an oil supply passage (oil passage). The oil passage supplies oil to the first oil chamber P1.

[0073] <Operation> The first brake operation state and the brake release state operate in the same manner as in the first embodiment.

[0074] When oil is not supplied from the first hydraulic supply source Q1, no hydraulic pressure is acting on the second oil chamber P2, and oil is supplied from the second hydraulic supply source Q2, acting on the first oil chamber P1, the hydraulic pressure in the first oil chamber P1 presses the auxiliary member 98, causing the pressing portion 98a to contact and press against the movable pressure-receiving surface 92e of the brake piston 92. As a result, the brake disc 90 and the separate plate 91 are pressed against each other more strongly than in the first brake operating state between the pressing portion 92a of the brake piston 92 and the brake regulating plate 93. The rotation of the drive shaft 20 relative to the casing 10 is restricted by a stronger pressing force than in the first brake operating state. This state is called the second brake operating state.

[0075] When oil is supplied from the first hydraulic supply source Q1 and the supply of oil from the second hydraulic supply source Q2 is stopped from the second brake operating state, hydraulic pressure acts on the second oil chamber P2, and the hydraulic pressure in the first oil chamber P1 is removed, eliminating the pressing force acting on the auxiliary member 98. As a result, the state in which the brake disc 90 and the separate plate 91 are pressed against each other between the pressing portion 92a of the brake piston 92 and the brake restricting plate 93 is eliminated. The restriction on the rotation of the drive shaft 20 relative to the casing 10 is released. In this way, the brake is released.

[0076] <Effects> As described above, in this embodiment, the hydraulic pressure of the first oil chamber P1 presses the auxiliary member 98, pressing the brake disc 90 more strongly than in the first brake operating state in the direction in which the drive shaft 20 and the brake piston 92 clamp the brake disc 90, thereby creating a second brake operating state. More specifically, in this embodiment, the hydraulic pressure of the first oil chamber P1 allows the brake piston 92 to slide via the auxiliary member 98 in the direction in which it clamps the brake disc 90 and the separate plate 91. According to this embodiment, a first brake operating state and a second brake operating state can be created. According to this embodiment, the first brake operating state and the second brake operating state can be used interchangeably.

[0077] [Third Embodiment] Figure 8 is a cross-sectional plan view of the auxiliary member, the first oil chamber, and the second oil chamber of the third embodiment. The third embodiment differs from the first embodiment in the auxiliary member (fourth member) 97, the auxiliary member (fourth member) 98, and the first oil chamber P1.

[0078] The auxiliary member 97 is positioned between the brake piston 92 and the casing 10 in the axial direction of the drive shaft 20. The auxiliary member 97 is a second columnar body positioned at the axial end of the auxiliary member 98. The auxiliary member 97 is slidably positioned on the end cover 12 of the casing 10 along the axis 20C of the drive shaft 20. The auxiliary member 97 has a pressing portion 97a at its other axial end. The auxiliary member 97 has a first oil chamber P1 positioned between it and the end cover 12 of the casing 10. The auxiliary member receives hydraulic pressure from the first oil chamber P1 and biases the brake piston 92 in the pressing direction.

[0079] The auxiliary member 98 is positioned between the brake piston 92 and the casing 10 in the axial direction of the drive shaft 20. The auxiliary member 98 is a first columnar body positioned at the axial end of the brake piston 92. The auxiliary member 98 is inserted through the brake spring 94. The auxiliary member 98 has a cylindrical body 98b inserted through the brake spring 94 and a head 98a with a larger diameter than the outer diameter of the brake spring 94. The head 98a protrudes from the brake spring 94 and is in contact with the movable pressure-receiving surface 92e of the brake piston 92. The auxiliary member 98 is pressed in the axial direction by an auxiliary member 97 that receives hydraulic pressure from the first oil chamber P1, and the pressed auxiliary member 98 biases the brake piston 92.

[0080] The first oil chamber P1 is located between the auxiliary member 97 and the casing 10 in the axial direction of the drive shaft 20. The first oil chamber P1 is located in the outer peripheral area of ​​the axial end of the auxiliary member 97. In the embodiment, the first oil chamber P1 is located between the outer peripheral portion of the auxiliary member 97 and the end cover 12 of the casing 10. In the embodiment, the first oil chamber P1 is an annular space provided around the auxiliary member 97. In the embodiment, the first oil chamber P1 presses the auxiliary member 97 with hydraulic pressure, allowing the brake piston 92 to slide via the auxiliary member 98 in a direction that clamps the brake disc 90 and the separate plate 91. The first oil chamber P1 is connected to a second hydraulic supply source Q2 by an oil supply passage (oil passage). The oil passage supplies oil to the first oil chamber P1.

[0081] <Operation> The first brake operation state and the brake release state operate in the same manner as in the first embodiment.

[0082] When oil is not supplied from the first hydraulic supply source Q1, no hydraulic pressure is acting on the second oil chamber P2, and oil is supplied from the second hydraulic supply source Q2, acting on the first oil chamber P1, the hydraulic pressure in the first oil chamber P1 presses the auxiliary member 97, causing the pressing portion 97a to contact the main body 98b of the auxiliary member 98. The auxiliary member 98 is pressed by the auxiliary member 97, causing the pressing portion 98a to contact and press against the movable pressure-receiving surface 92e of the brake piston 92. As a result, the brake disc 90 and the separate plate 91 are pressed more strongly against each other between the pressing portion 92a of the brake piston 92 and the brake regulating plate 93 than in the first brake operating state. The rotation of the drive shaft 20 relative to the casing 10 is restricted by a stronger pressing force than in the first brake operating state. This state is called the second brake operating state.

[0083] When oil is supplied from the first hydraulic supply source Q1 and the supply of oil from the second hydraulic supply source Q2 is stopped from the second brake operating state, hydraulic pressure acts on the second oil chamber P2, and the hydraulic pressure in the first oil chamber P1 is removed, eliminating the pressing force acting on the auxiliary member 97. As a result, the pressing force acting on the auxiliary member 98 is released, and the state in which the brake disc 90 and the separate plate 91 are pressed against each other between the pressing portion 92a of the brake piston 92 and the brake regulating plate 93 is eliminated. The restriction on the rotation of the drive shaft 20 relative to the casing 10 is released. In this way, the brake is released.

[0084] <Effects> As described above, in this embodiment, the hydraulic pressure of the first oil chamber P1 presses the auxiliary member 97, and through the auxiliary member 98, the brake disc 90 is pressed more strongly than in the first brake operating state in the direction in which it is clamped between the drive shaft 20 and the brake piston 92, thereby creating a second brake operating state. More specifically, in this embodiment, the hydraulic pressure of the first oil chamber P1 makes the brake piston 92 slidable through the auxiliary members 97 and 98 in the direction in which it clamps the brake disc 90 and the separate plate 91. According to this embodiment, a first brake operating state and a second brake operating state can be created. According to this embodiment, the first brake operating state and the second brake operating state can be used interchangeably.

[0085] 1...Hydraulic motor, 9...Brake device, 10...Casing, 11...Casing body, 11b...Housing space, 11d...Housing space, 11e...Housing space, 11h...Oil supply passage (oil channel), 11i...Oil supply passage (oil channel), 12...End cover, 20...Drive shaft (rotating shaft), 20C...Axis center, 30...Cylinder block, 30C...Axis center, 40...Piston rod, 42...Second tapered roller bearing, 42a...Tapered roller, 42b...Roller housing, 50...Center shaft, 90...Brake disc (first member), 91...Separate plate (second member), 92...Brake piston (third member), 93...Brake regulating plate, 94...Brake spring (spring), 97...Auxiliary member (fourth member), P1...First oil chamber, P2...Second oil chamber.

Claims

1. A hydraulic motor comprising: a casing; a rotating shaft rotatably supported by the casing; a first member positioned on the outer circumference of the rotating shaft such that its relative rotation with the rotating shaft is restricted; a second member positioned adjacent to the first member in the axial direction of the rotating shaft such that its relative rotation with the casing is restricted; a third member movable in the axial direction of the rotating shaft and positioned alongside the first and second members in the axial direction; a spring that biases the third member so that it presses against the first and second members; and a first oil chamber that, when oil is introduced, generates hydraulic pressure that biases the third member in the same direction as the biasing direction of the spring.

2. The hydraulic motor according to claim 1, comprising a second oil chamber that, when oil is introduced, generates hydraulic pressure that biases the third member in the opposite direction to the biasing direction of the spring.

3. An auxiliary member interposed between the third member and the casing, wherein the third member has a pressure-receiving surface facing the first oil chamber, and the first oil chamber is located between the pressure-receiving surface of the third member and the auxiliary member, the hydraulic motor according to claim 1.

4. The hydraulic motor according to claim 3, wherein the auxiliary member seals the space between the third member and the casing.

5. A hydraulic motor according to claim 1, comprising a fourth member disposed between the third member and the casing in the axial direction of the rotating shaft, wherein the first oil chamber is located between the fourth member and the casing in the axial direction of the rotating shaft, and the fourth member receives hydraulic pressure from the first oil chamber to bias the third member in the same direction.

6. The hydraulic motor according to claim 5, wherein the fourth member is a columnar body inserted through the spring.

7. The hydraulic motor according to claim 5, wherein the fourth member comprises a first columnar body inserted through the spring and a second columnar body arranged to be movable in the axial direction of the rotation shaft relative to the casing, the first oil chamber is located between the second columnar body and the casing, and the fourth member is such that the second columnar body, receiving hydraulic pressure from the first oil chamber, presses the first columnar body in the axial direction, and the pressed first columnar body biases the third member.

8. The hydraulic motor according to claim 2, wherein the casing comprises a second oil passage for supplying oil to the second oil chamber and a first oil passage for supplying oil to the first oil chamber.

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