JP2010150990A - Axial piston pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress leaking of fluid along a space between a fitting inner circumference face of a cylinder block and a fitting outer circumference face of a static shaft. <P>SOLUTION: A cylinder shaped valve element 34 is provided between the fitting inner circumference face 24 of the cylinder block 20 and the fitting outer circumference face 23 of the static shaft 16. The static shaft 16 is fit in a cylinder of the cylinder shaped valve element 34. The fitting outer circumference face 23 being an outer circumference face of the static shaft 16 is a circumferential face, and the fitting inner circumference face 24 is a circumferential face. A window 38 is formed in the valve element 34 in a suction stroke corresponding area Ps side. The window 38 is communicated with a suction passage 29, and an inlet 30 is intermittently communicated with the window 38 in response to a rotation angle of the cylinder block 20. The valve element 34 intermittently blocks the inlet 30 in response to the rotation angle of the cylinder block 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an axial piston pump in which a cylinder block rotates and a piston reciprocates.

  In the axial piston pump disclosed in Patent Document 1, a cylinder block is rotatably fitted to a pintle valve (fixed shaft). A communication port communicating with the side of the cylinder bore in the cylinder block is formed in the cylinder block, and a suction passage and a discharge passage are formed in the pintle valve. When the communication port communicates with the suction passage according to the rotation angle of the cylinder block, the fluid in the suction passage is sucked into the cylinder bore, and when the communication port communicates with the discharge passage, the fluid in the cylinder bore is discharged into the discharge passage.

  The piston in the cylinder block reciprocates due to the cam action of the swash plate (cam body), and this cam action also applies a load in the radial direction to the piston. Specifically, a radial load from the top dead center corresponding portion side to the bottom dead center corresponding portion side of the cam body is applied to the tip end side (side closer to the swash plate) of the cylinder block via the piston. A cylinder block that obtains rotational driving force from the rotating shaft is splined to the inner end of the rotating shaft.

The cylinder block is supported on the base side of the pintle valve via a radial bearing interposed between the outer peripheral surface of the pintle valve and the inner peripheral surface of the cylinder block. Further, the cylinder block is supported by a radial bearing interposed between the inner peripheral surface of the housing and the outer peripheral surface of the cylinder block on the tip side (the side close to the swash plate) of the pintle valve.
JP-A-62-58065

  The presence of radial clearance in the spline connection and radial clearance in the radial bearing allows the cylinder block to move in the radial direction. Therefore, the cam action moves the cylinder block from the top dead center corresponding part side to the bottom dead center corresponding part side. If the clearance between the fitting inner peripheral surface of the cylinder block and the fitting outer peripheral surface of the pintle valve is small, the front end side (side closer to the swash plate) of the cylinder block is the rear end side (pintle valve). The cylinder block is tilted. Such inclination of the cylinder block deteriorates the parallelism between the fitting inner peripheral surface of the cylinder block and the fitting outer peripheral surface of the pintle valve, and causes fluid leakage from a portion where local wear or clearance is enlarged. If the cylinder block moves in the radial direction, tilting of the cylinder block can be avoided. For this purpose, the clearance between the fitting inner peripheral surface of the cylinder block and the fitting outer peripheral surface of the pintle valve is defined as the clearance of the radial clearance in the spline connection and the sum of the radial clearances in the radial bearing. It must be large enough to allow movement of minutes.

  However, the size of the clearance between the inner peripheral surface of the cylinder block and the outer peripheral surface of the pintle valve is such that the inner peripheral surface of the cylinder block and the outer periphery of the pintle valve (fixed shaft) are fitted. Increase fluid leakage from clearance between surfaces.

  An object of the present invention is to prevent fluid from leaking along a fitting inner peripheral surface of a cylinder block and a fitting outer peripheral surface of a fixed shaft.

  In the present invention, a cylinder block that is rotatably fitted to a fixed shaft rotates about the fixed shaft, and the fixed shaft protrudes from a base housing that faces an end surface of the cylinder block, A piston is accommodated in a cylinder bore formed in the cylinder block so as to be able to reciprocate. The piston receives a cam action from a cam body by the rotation of the cylinder block and reciprocates. An axial piston pump in which fluid is sucked into the cylinder bore and fluid in the cylinder bore is discharged as the piston moves forward. In the invention of claim 1, the fluid passage formed in the fixed shaft and the cylinder bore And the cylinder is intermittently communicated with the fluid passage according to the rotation angle of the cylinder block. A communication port formed in the fitting inner peripheral surface of the block, a valve body having a window interposed between the fitting outer peripheral surface of the fixed shaft and the fitting inner peripheral surface of the cylinder block, and the fixed shaft Rotation prevention means for preventing rotation of the valve body relative to the valve body, the valve body being in a direction perpendicular to the rotation axis of the cylinder block and at least the top dead center corresponding portion of the cam body and the cam body Movement in the direction from one to the other with respect to the bottom dead center corresponding part is allowed.

  The cam action received from the cam body attempts to move the cylinder block in a direction from the top dead center corresponding portion toward the bottom dead center corresponding portion of the cam body. When the cylinder block moves, the valve element interposed between the fitting outer peripheral surface of the fixed shaft and the fitting inner peripheral surface of the cylinder block also moves, and the fitting inner peripheral surface of the cylinder block and the fixed shaft The leakage of fluid along the outer peripheral surface of the fitting is suppressed.

  In a preferred example, a movement restricting means for restricting movement of the cylinder block in a direction orthogonal to a direction from one of the top dead center corresponding part and the bottom dead center corresponding part to the other is provided.

  The fluid pressure in the cylinder bore in the discharge stroke corresponding region applies a load in a direction perpendicular to the direction from the top dead center corresponding portion to the bottom dead center corresponding portion to the cylinder block. The fluid pressure of the discharge pressure acts on the valve body from the communication port formed on the fitting inner peripheral surface of the cylinder block, and the cylinder block tends to be separated from the valve body. Since the movement restricting means restricts the movement of the cylinder block due to the load, the clearance between the fitting inner peripheral surface of the cylinder block and the valve body does not increase, and the cylinder block is inclined by the cam action received from the cam body. There is nothing.

  In a preferred example, the movement restricting means is located between the fitting inner peripheral surface of the cylinder block and the fitting outer peripheral surface of the fixed shaft on the suction stroke corresponding region side, or on the discharge stroke corresponding region side. A plain bearing interposed between an outer peripheral surface of the cylinder block and a fixed surface opposed to the outer peripheral surface, and the plain bearing is arranged in a direction perpendicular to the rotation axis of the cylinder block. Allow movement.

A plain bearing is simple as a movement restricting means.
In a preferred example, the rotation preventing means is a key fitting mechanism or an uneven fitting mechanism provided between the valve body and an outer peripheral surface of the fixed shaft, and the key fitting mechanism or the uneven fitting mechanism. Allows movement of the valve body in a direction perpendicular to the rotation axis of the cylinder block.

The key fitting mechanism or the concave-convex fitting mechanism is simple as a mechanism that allows movement of the valve body in a direction perpendicular to the rotation axis.
In a preferred example, the valve body is a cylindrical valve body surrounding the fixed shaft, and the valve body communicates with the fluid passage and is connected to the communication port according to a rotation angle of the cylinder block. It has windows that communicate intermittently.

  Cylindrical valve body, in order to prevent the fluid in the cylinder bore in the discharge stroke corresponding region from leaking from the communication port along the fitting outer peripheral surface of the fixed shaft and the fitting inner peripheral surface of the cylinder block, Is preferred.

In a preferred example, the fluid passage is a suction passage, and the window intermittently communicates with the communication port in the suction stroke corresponding region according to the rotation angle of the cylinder block.
The configuration in which the suction passage is provided in the fixed shaft is suitable for increasing the passage cross-sectional area and preventing the occurrence of cavitation.

  In a preferred example, the valve body is fitted in the cylinder block on the discharge stroke corresponding region side so as to intermittently close the communication port of the discharge stroke corresponding region according to the rotation angle of the cylinder block. It is a discharge side valve body interposed between the peripheral surface and the fitting outer peripheral surface of the fixed shaft.

The discharge-side valve element prevents fluid in the cylinder bore in the discharge stroke corresponding region from leaking from the communication port along the fitting outer peripheral surface of the fixed shaft and the fitting inner peripheral surface of the cylinder block.
In a preferred example, the end face of the cylinder block communicates with the discharge passage formed in the base housing, the cylinder bore, and intermittently communicates with the discharge passage according to the rotation angle of the cylinder block. A discharge plate formed between the base surface of the base housing and the end surface of the cylinder block; and the discharge passage is opposed to the end surface of the cylinder block. An arc-shaped discharge connection port extending in the circumferential direction of the fixed shaft is provided along the base surface of the housing, and the discharge connection port is formed in the valve plate so as to penetrate the valve plate.

  Clearance does not increase between the end face of the cylinder block and the valve plate, and fluid leakage from the discharge port of the cylinder bore to the end face of the cylinder block and the valve plate is suppressed.

  The axial piston pump of the present invention has an excellent effect that it is possible to prevent fluid from leaking between the fitting inner peripheral surface of the cylinder block and the fitting outer peripheral surface of the fixed shaft.

A first embodiment in which the present invention is embodied in a fixed displacement axial piston pump will be described below with reference to FIGS.
As shown in FIG. 1, a front housing 12 is connected to the base housing 11, and a rotating shaft 13 is rotatably supported on the front housing 12 via a radial bearing 14. A fixed shaft 16 projects from the base surface 15, which is the inner end surface of the base housing 11, in the direction of the rotational axis 131 of the rotating shaft 13, and a support recess 17 is formed in the distal end surface 161 of the fixed shaft 16. Yes. The inner end 132 of the rotary shaft 13 is rotatably supported by the fixed shaft 16 via the radial bearing 18 in the support recess 17.

  An annular cam body 19 is fixedly provided in the front housing 12, and the rotation shaft 13 is passed through the ring of the cam body 19. The cam surface 191 of the cam body 19 is an annular flat surface facing the base surface 15 of the base housing 11 and is inclined with respect to the rotation axis 131 of the rotation shaft 13.

  An annular cylinder block 20 is supported on the rotary shaft 13 so as to be integrally rotatable with the rotary shaft 13 through spline coupling. A valve plate 21 is interposed between the end surface 201 of the cylinder block 20 facing the base surface 15 and the base surface 15. The valve plate 21 is fixed in surface contact with the base surface 15, and the end surface 201 of the cylinder block 20 is in surface contact with the end surface 211 of the valve plate 21.

  A fitting hole 22 is recessed in the cylinder block 20 from the end face 201 side. A cylindrical valve body 34 is fitted in the fitting hole 22, and the fixed shaft 16 is fitted in the cylinder of the cylindrical valve body 34. The fitting outer peripheral surface 23 that is the outer peripheral surface of the fixed shaft 16 is a circumferential surface, and the fitting inner peripheral surface 24 that is the inner peripheral surface of the fitting hole 22 is a circumferential surface. The valve body 34 is interposed between the fitting outer peripheral surface 23 and the fitting inner peripheral surface 24. The curvature radius of the outer peripheral surface 341 of the circumferential shape of the valve body 34 is slightly smaller than the curvature radius of the fitting inner peripheral surface 24 of the cylinder block 20.

  The radial clearance C1 between the inner peripheral surface 342 of the valve body 34 and the fitting outer peripheral surface 23 of the fixed shaft 16 is the outer peripheral surface 341 of the cylindrical valve body 34 and the fitting inner peripheral surface 24 of the cylinder block 20. It is larger than the clearance C2 in the radial direction between. The size of the clearance C <b> 1 is set to be equal to or greater than the sum of the radial clearance in the spline connection between the rotating shaft 13 and the cylinder block 20 and the radial clearance in the radial bearing 18.

  As shown in FIG. 2, a positioning groove 35 extending in the direction of the rotation axis 131 is formed in the fitting outer peripheral surface 23 of the fixed shaft 16, and the inner peripheral surface of the valve body 34 is formed in the direction of the rotation axis 131. The extending positioning groove 36 is formed to be recessed so as to face the positioning groove 35. A key 37 is fitted and fixed in the positioning groove 35. The key 37 is loosely fitted in the positioning groove 36. The key 37 loosely fitted in the positioning groove 36 allows the valve body 34 to move in a direction perpendicular to the rotation center (that is, the rotation axis 131) of the cylinder block 20, but the valve around the fixed shaft 16. A key fitting mechanism (rotation preventing means) for preventing the rotation of the body 34 is configured. When the cylinder block 20 rotates, the fitting inner circumferential surface 24 circulates around the fitting outer circumferential surface 23 and the valve body 34.

  FIG. 6A is a development view of the fitting inner peripheral surface 24 of the cylinder block 20 and the inner peripheral surface of the cylindrical valve body 34. FIG. 6B is a development view of the outer peripheral surface of the fitting outer peripheral surface 23 of the fixed shaft 16 and the cylindrical valve body 34.

  As shown in FIG. 1, in the radial direction of the rotary shaft 13, the cylinder block 20 on the outer side of the fitting inner peripheral surface 24 has a plurality of cylinder bores 25 extending from the end surface 202 of the cylinder block 20 facing the cam surface 191. It is recessed in the direction. A piston 26 is fitted in each cylinder bore 25 so as to be able to reciprocate in the direction of the rotation axis 131. A spherical joint 261 is integrally formed at the end of the piston 26 facing the cam surface 191, and a shoe 27 is connected to the spherical joint 261. Each shoe 27 is in surface contact with the cam surface 191 while being anchored to the annular retainer 28.

When the cylinder block 20 rotates with the rotation of the rotating shaft 13, the shoe 27 slides on the cam surface 191 and the piston 26 reciprocates in the cylinder bore 25.
A suction passage 29 is formed in the base housing 11. An inlet 291 of the suction passage 29 as a fluid passage opens on the outer end surface 111 of the base housing 11, and an outlet 292 of the suction passage 29 opens on the fitting outer peripheral surface 23 of the fixed shaft 16. That is, the suction passage 29 extends from the outer end surface 111 of the base housing 11 to the fitting outer peripheral surface 23 through the fixed shaft 16.

As shown in FIGS. 3 and 5, a window 38 is formed on the circumferential surface of the cylindrical valve body 34 so as to communicate with the outlet 292.
As shown in FIG. 3, a suction port 30 is formed on the fitting inner peripheral surface 24 of the cylinder block 20 so as to communicate with the cylinder bore 25 on a one-to-one basis. The suction port 30 as a communication port is located inside the cylinder bore 25 in the radial direction of the cylinder block 20, and the window 38 is located inside the suction port 30 in the radial direction of the cylinder block 20. The outlet 292 is inside the window 38 in the radial direction of the cylinder block 20. As the cylinder block 20 rotates, the suction port 30 moves in the circumferential direction and communicates with the window 38 intermittently.

  As shown in FIG. 1, a discharge passage 31 is formed in the base housing 11 and the valve plate 21. A discharge connection port 311 as an inlet of the discharge passage 31 opens in the end surface 211 of the valve plate 21, and an outlet 312 of the discharge passage 31 opens on the outer end surface 111 of the base housing 11. That is, the discharge passage 31 extends from the end surface 211 of the valve plate 21 through the valve plate 21 and the base housing 11 to the outer end surface 111.

As shown in FIG. 4, the discharge connection port 311 has an arc shape extending in the circumferential direction around the rotation axis 131.
A discharge port 32 is formed on the end surface 201 of the cylinder block 20 so as to communicate with the cylinder bore 25 on a one-to-one basis. As the cylinder block 20 rotates, the discharge port 32 moves in the circumferential direction and intermittently communicates with the discharge connection port 311.

  As shown in FIG. 2, the rotating shaft 13 and the cylinder block 20 rotate in the direction of arrow R. When viewed in the direction of the rotation axis 131 of the rotation shaft 13, one space divided by a virtual plane H including the rotation axis 131 (a region where one half of the cam surface 191 is projected in the direction of the rotation axis 131) is an intake stroke. The corresponding region Ps and the other (the region where the other half of the cam surface 191 is projected in the direction of the rotation axis 131) is the discharge stroke corresponding region Pd. When viewed in the direction of the rotation axis 131 of the rotary shaft 13, the piston 26 corresponding to the suction stroke corresponding region Ps is in the suction stroke, and the piston 26 corresponding to the discharge stroke corresponding region Pd is in the discharge stroke. In the cam surface 191, a portion corresponding to the piston 26 located at the bottom dead center is the bottom dead center corresponding portion Hd, and a portion corresponding to the piston 26 located at the top dead center is the top dead center corresponding portion Ht. The bottom dead center corresponding part Hd and the top dead center corresponding part Ht defined on the cam surface 191 intersect with the virtual plane H.

As shown in FIG. 3, the outlet 292 is in the suction stroke corresponding region Ps.
As shown in FIG. 4, the arc-shaped discharge connection port 311 is in the discharge stroke corresponding region Pd.
The rotation angle of the cylinder block 20 in FIGS. When the cylinder block 20 rotates halfway from the state of FIGS. 2 to 4, the rotation angle of the cylinder block 20 becomes 180 °, and when the cylinder block 20 rotates once from the state of FIGS. 2 to 4, the rotation angle of the cylinder block 20. Is 360 ° (0 °).

  In a state where the piston 26 moves backward (moving from the right side to the left side in FIG. 1) as the cylinder block 20 rotates (intake stroke), the suction port 30 of the cylinder bore 25 in which the piston 26 is fitted into the window 38. The fluid in the suction passage 29 is sucked into the cylinder bore 25 through the window 38 and the suction port 30. When the piston 26 moves forward (moving from the left side to the right side in FIG. 1) in accordance with the rotation of the cylinder block 20 (discharge stroke), the discharge port 32 of the cylinder bore 25 into which the piston 26 is fitted is connected to the discharge connection port. The fluid in the cylinder bore 25 is discharged to the discharge passage 31 via the discharge port 32.

  That is, the plurality of suction ports 30 are formed in the fitting inner peripheral surface 24 of the cylinder block 20 so as to intermittently communicate with the window 38 according to the rotation angle of the cylinder block 20. The plurality of discharge ports 32 are formed in the cylinder block 20 so as to intermittently communicate with the discharge connection port 311 of the discharge passage 31 according to the rotation angle of the cylinder block 20.

  The cam action received from the cam surface 191 of the cam body 19 is the direction from one of the top dead center corresponding portion Ht of the cam surface 191 and the bottom dead center corresponding portion Hd of the cam surface 191 [shown by an arrow Q in FIG. The cylinder block 20 is moved in the direction. Further, the valve body 34 follows the movement of the cylinder block 20. Since the valve body 34 fitted to the cylinder block 20 is allowed to move in a direction perpendicular to the rotation axis 131, one of the top dead center corresponding portion Ht and the bottom dead center corresponding portion Hd is changed from one to the other. The movement of the cylinder block 20 and the valve body 34 in the direction Q toward the center is a parallel movement in the radial direction, and the cylinder block 20 does not tilt.

In the first embodiment, the following effects can be obtained.
(1) When there is no valve element 34 that can move in a direction perpendicular to the rotation axis 131, the diameter between the fitting inner peripheral surface 24 of the cylinder block 20 and the fitting outer peripheral surface 23 of the fixed shaft 16. The clearance in the direction needs to be about the clearance C1.

  The valve body 34 interposed between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 is the fitting inner peripheral surface 24 of the cylinder block 20 and the outer peripheral surface 341 of the valve body 34. It is possible to reduce the size C2 (<C1) of the clearance in the radial direction as small as possible. That is, the valve body 34 is a sealing surface facing the fitting inner peripheral surface 24 of the cylinder block 20 (the outer peripheral surface 341 when the valve body 34 is provided, and the outer periphery of the fixed shaft 16 when there is no valve body 34. This contributes to a reduction in the clearance between the surface 23) and the fitting inner peripheral surface 24 of the cylinder block 20. As a result, the fluid in the cylinder bore 25 is prevented from leaking from the suction port 30 (communication port) between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20.

  (2) The cam action received from the cam surface 191 of the cam body 19 attempts to move the cylinder block 20 in the direction Q from one of the top dead center corresponding part Ht and the bottom dead center corresponding part Hd to the other. Since this movement is a parallel movement in the radial direction, the cylinder block 20 does not tilt. Accordingly, local wear between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 and leakage due to an increase in clearance can be prevented. Further, the clearance does not increase between the end surface 201 of the cylinder block 20 and the end surface 211 of the valve plate 21, and from the discharge port 32 of the cylinder bore 25 to between the end surface 201 of the cylinder block 20 and the end surface 211 of the valve plate 21. Fluid leakage is suppressed.

  (3) The key fitting mechanism using the key 37 is simple as a mechanism that allows the valve body 34 to move in a direction perpendicular to the rotation axis 131 and prevents the valve body 34 from rotating relative to the fixed shaft 16. It is.

  (4) By making the diameter of the outer peripheral surface of the cylindrical valve body 34 as close as possible to the diameter of the fitting inner peripheral surface 24 of the cylinder block 20, the size of the clearance C2 can be made as small as possible. it can. In such a cylindrical valve body 34, the fluid in the cylinder bore 25 in the discharge stroke corresponding region Pd passes between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 from the suction port 30. And the fluid in the cylinder bore 25 in the suction stroke corresponding region Ps is prevented from leaking from the suction port 30 between the fitting outer peripheral surface 23 and the fitting inner peripheral surface 24. It is preferable.

  (5) In the axial piston pump configured to discharge through the discharge passage 31 of the valve plate 21, the end face of the cylinder block 20 is pressed against the valve plate 21 by the pressure in the cylinder bore 25, and the gap between the end face and the valve plate 21 is reduced. Since it is necessary to eliminate the occurrence, the diameter of the discharge port 32 is made small. Accordingly, in the type in which fluid is sucked from the discharge port 32 to the cylinder bore 25, reducing the diameter of the discharge port 32 that also serves as the suction port increases the suction resistance and causes cavitation in the suction fluid. The occurrence of cavitation leads to a decrease in volumetric efficiency and noise deterioration.

  Since only the suction passage 29 of the suction passage 29 and the discharge passage 31 is formed in the fixed shaft 16, the cross-sectional area of the suction passage 29 can be increased, and the occurrence of cavitation can be avoided. Further, since the suction port 30 is inside the cylinder bore 25 in the radial direction of the cylinder block 20, the centrifugal force accompanying the rotation of the cylinder block 20 assists the fluid suction from the suction passage 29 to the cylinder bore 25 through the suction port 30. To do. This contributes to avoiding a decrease in inhalation efficiency.

  (6) The cavitation in the suction fluid is such that the greater the distance between the suction port and the rotation center of the cylinder block 20 (that is, the rotation axis 131 of the rotation shaft 13), that is, the peripheral speed of the suction port associated with the rotation of the cylinder block 20 The larger the value, the easier it is to generate. The suction port 30 formed in the fitting inner peripheral surface 24 has a shorter distance from the rotation center of the cylinder block 20 than the suction port formed in the end surface 201 of the conventional cylinder block 20. The configuration in which the suction port 30 is formed in the fitting inner peripheral surface 24 contributes to suppression of the occurrence of cavitation.

Next, a second embodiment of FIG. 7 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
A discharge-side valve element 39 having an arcuate cross section when viewed from the direction of the rotation axis 131 is interposed between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 on the discharge stroke corresponding region Pd side. Has been. The radius of curvature of the outer peripheral surface 391 of the circumferential surface shape of the discharge side valve element 39 is slightly smaller than the radius of curvature of the fitting inner peripheral surface 24 of the cylinder block 20.

  A positioning groove 40 extending in the direction of the rotation axis 131 is formed in the fitting outer peripheral surface 23 of the fixed shaft 16, and a positioning groove 41 extending in the direction of the rotation axis 131 is formed on the inner peripheral surface of the discharge side valve body 39. A recess is formed so as to face the positioning groove 40. A key 42 is fitted and fixed in the positioning groove 40. The key 42 is loosely fitted in the positioning groove 41. The key 42 loosely fitted in the positioning groove 41 allows the discharge side valve body 39 to move in a direction perpendicular to the rotation axis 131, but prevents the discharge side valve body 39 from rotating around the fixed shaft 16. The key fitting mechanism (rotation prevention means) is configured. When the cylinder block 20 rotates, the fitting inner circumferential surface 24 circulates around the fitting outer circumferential surface 23 and the discharge side valve body 39.

  A recess 43 is formed in the fitting outer peripheral surface 23 of the fixed shaft 16 on the suction stroke corresponding region Ps side, and a plain bearing 44 is fitted and fixed in the recess 43. The concave portion 43 is located at a position facing the piston 26 corresponding to an intermediate position between the bottom dead center corresponding portion Hd and the top dead center corresponding portion Ht on the suction stroke corresponding region Ps side (perpendicular to the virtual plane H and includes a rotation axis 131. On the plane). The plain bearing 44 interposed between the fitting outer peripheral surface 23 as the fixed surface and the fitting inner peripheral surface 24 of the cylinder block 20 corresponds to the top dead center corresponding portion Ht and the bottom dead center relative to the cylinder block 20. The cylinder block 20 is allowed to move in the direction Q from the one side to the other side with the portion Hd.

The plain bearing 44 constitutes a movement restricting means that allows the cylinder block 20 to move in the direction perpendicular to the rotation axis 131 and in the direction of the arrow Q, but prevents movement in other directions.
In the second embodiment, the same effect as in the first embodiment can be obtained. The plain bearing 44 interposed between the fitting outer peripheral surface 23 and the fitting inner peripheral surface 24 on the suction stroke corresponding region Ps side is in a direction orthogonal to the direction Q and from the discharge stroke corresponding region Pd side. The cylinder block 20 is pressed toward the corresponding area Ps. Therefore, the clearance between the fitting inner peripheral surface 24 and the discharge side valve element 39 is reduced on the discharge stroke corresponding region Pd side, and the effect of suppressing fluid leakage from between the cylinder block 20 and the discharge side valve element 39 is obtained. It gets even higher.

Next, a third embodiment of FIG. 8 will be described. The same reference numerals are used for the same components as those in the second embodiment, and detailed description thereof is omitted.
A recess 45 is formed in the inner peripheral surface 122 of the cylindrical portion 121 of the front housing 12 on the discharge stroke corresponding region Pd side, and a plain bearing 46 is fitted and fixed to the recess 45. The concave portion 45 is a position facing the piston 26 corresponding to an intermediate position between the bottom dead center corresponding portion Hd and the top dead center corresponding portion Ht on the discharge stroke corresponding region Pd side (a plane orthogonal to the virtual plane H and including the rotation axis 131). Above). The plain bearing 46 interposed between the inner peripheral surface 122 as a fixed surface of the cylinder portion 121 and the outer peripheral surface 203 of the cylinder block 20 corresponds to the top dead center corresponding portion Ht and the bottom dead center relative to the cylinder block 20. The movement of the cylinder block 20 in the direction Q from the one side to the other side with the portion Hd is allowed, but the movement in the other direction is prevented.

The plain bearing 46 constitutes a movement restricting means that allows the cylinder block 20 to move in the direction of the arrow Q perpendicular to the rotation axis 131 but prevents movement in the other direction.
In the third embodiment, the same effect as in the second embodiment can be obtained.

Next, a fourth embodiment of FIG. 9 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
A discharge side valve element 47 having an arc shape in section when viewed from the direction of the rotation axis 131 is interposed between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 on the discharge stroke corresponding region Pd side. Has been. The radius of curvature of the outer peripheral surface 471 of the circumferential surface shape of the discharge side valve element 47 is slightly smaller than the radius of curvature of the fitting inner peripheral surface 24 of the cylinder block 20. Between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 on the suction stroke corresponding region Ps side, a suction side valve body 48 having an arcuate cross section when viewed from the direction of the rotation axis 131 is interposed. Has been. The radius of curvature of the outer peripheral surface 481 of the circumferential surface shape of the suction side valve body 48 is slightly smaller than the radius of curvature of the fitting inner peripheral surface 24 of the cylinder block 20.

  A concave portion 49 is formed in the fitting outer peripheral surface 23 of the fixed shaft 16 on the discharge stroke corresponding region Pd side, and the discharge side valve body 47 is loosely fitted in the concave portion 49. Further, a recess 50 is formed in the fitting outer peripheral surface 23 of the fixed shaft 16 on the suction stroke corresponding region Ps side, and the suction side valve body 48 is loosely fitted in the recess 50. A window 38 is formed in the suction side valve body 48. The concave portion 49 allows the discharge-side valve element 47 to move in a direction perpendicular to the rotation axis 131 but prevents the discharge-side valve element 47 from rotating around the fixed shaft 16. Means). The recess 50 allows the suction side valve body 48 to move in a direction perpendicular to the rotation axis 131 but prevents the suction side valve body 48 from rotating around the fixed shaft 16. Means). When the cylinder block 20 rotates, the fitting inner circumferential surface 24 circulates around the fitting outer circumferential surface 23, the discharge side valve body 47 and the suction side valve body 48.

In the fourth embodiment, the same effect as in the first embodiment can be obtained.
Next, a fifth embodiment shown in FIGS. 10 to 13 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.

As shown in FIG. 10, a cylindrical suction side valve body 51 is fitted in the fitting hole 22, and the fixed shaft 16 is fitted in the cylinder of the cylindrical suction side valve body 51. .
As shown in FIG. 12, the outer peripheral surface of the cylindrical suction side valve body 51 includes a large-diameter outer peripheral surface 511, a small-diameter outer peripheral surface 512 having a smaller diameter than the large-diameter outer peripheral surface 511, and a large-diameter outer peripheral surface 511 and a small-diameter outer periphery. It consists of a pair of steps 513 and 514 connecting the surface 512. The large-diameter outer peripheral surface 511 is on the suction stroke corresponding region Ps side, and the small-diameter outer peripheral surface 512 is on the discharge stroke corresponding region Pd side. The large-diameter outer peripheral surface 511 is a circumferential surface, and the curvature radius of the large-diameter outer peripheral surface 511 having a circumferential shape is slightly smaller than the curvature radius of the fitting outer peripheral surface 23 of the cylinder block 20.

  A window 38 is provided through the large-diameter outer peripheral surface 511 of the suction side valve body 51. The window 38 (shown also in FIG. 11A) communicates with the outlet 292 of the suction passage 29. As the cylinder block 20 rotates, the suction port 30 moves in the circumferential direction and communicates with the window 38 intermittently.

  As shown in FIG. 11B, a discharge side valve body 52 is interposed between the small diameter outer peripheral surface 512 of the suction side valve body 51 and the fitting inner peripheral surface 24. The outer peripheral surface 521 and the inner peripheral surface 522 of the discharge side valve body 52 are circumferential surface shapes. The curvature radius of the outer peripheral surface 521 is slightly smaller than the curvature radius of the fitting inner peripheral surface 24, and the curvature radius of the inner peripheral surface 522 is larger than the curvature radius of the small-diameter outer peripheral surface 512 of the suction side valve body 51. It is enlarged. The side end surface 523 of the discharge side valve body 52 can contact the step 513 of the suction side valve body 51, and the side end surface 524 of the discharge side valve body 52 can contact the step 514 of the suction side valve body 51. The small-diameter outer peripheral surface 512 and the steps 513 and 514 form a recess into which the discharge-side valve body 52 is fitted. The concave portion extends in a direction perpendicular to the rotation axis 131 (a direction indicated by an arrow T perpendicular to a direction indicated by an arrow Q from one of the top dead center corresponding portion Ht and the bottom dead center corresponding portion Hd). A discharge-side uneven fitting mechanism (discharge) that allows movement of the discharge-side valve body 52 but prevents rotation of the discharge-side valve body 52 around the fixed shaft 16 by contact between the side end surfaces 523 and 524 and the steps 513 and 514. Side rotation prevention means).

  An annular groove 53 is formed in the small-diameter outer peripheral surface 512 of the suction side valve body 51, and a seal ring 54 is fitted in the annular groove 53. The seal ring 54 forms a back pressure chamber 55 in the ring and between the inner peripheral surface 522 of the discharge side valve body 52 and the small diameter outer peripheral surface 512 of the suction side valve body 51. A pair of introduction passages 56 and 57 are provided through the discharge side valve body 52. The introduction paths 56 and 57 communicate with the back pressure chamber 55.

  As the cylinder block 20 rotates, the suction port 30 on the discharge stroke corresponding region Pd side intermittently communicates with the introduction passages 56 and 57, and the back pressure chamber 55 passes through the introduction passages 56 and 57 and the suction port 30. The cylinder bore 25 communicates intermittently with the corresponding region Pd side. As a result, the pressure in the cylinder bore 25 on the discharge stroke corresponding region Pd side (discharge pressure) is in the back pressure chamber 55. The back pressure area of the back pressure chamber 55 with respect to the discharge side valve body 52 is larger than the passage sectional area of the suction ports 30 of all the cylinder bores 25 on the discharge stroke corresponding region Pd side. Accordingly, the pressure in the back pressure chamber 55 (back pressure corresponding to the discharge pressure) presses the outer peripheral surface 521 of the discharge side valve body 52 against the fitting inner peripheral surface 24 of the cylinder block 20 on the discharge stroke corresponding region Pd side. Further, the pressure in the back pressure chamber 55 (back pressure corresponding to the discharge pressure) pushes the large-diameter outer peripheral surface 511 of the suction side valve body 51 against the fitting inner peripheral surface 24 of the cylinder block 20 on the suction stroke corresponding region Ps side. Touch.

  The back pressure chamber 55 is engaged by energizing the discharge side valve body 52 from the fitting outer peripheral surface 23 side of the fixed shaft 16 toward the fitting inner peripheral surface 24 side of the cylinder block 20 on the discharge stroke corresponding region Pd side. It is a discharge-side urging means that presses against the inner peripheral surface 24. Further, the back pressure chamber 55 biases the suction side valve body 51 from the fitting outer peripheral surface 23 side of the fixed shaft 16 toward the fitting inner peripheral surface 24 side of the cylinder block 20 on the suction stroke corresponding region Ps side. This is suction side biasing means for pressing the fitting inner peripheral surface 24.

  In a state where the piston 26 moves backward (moving from the right side to the left side in FIG. 10) with the rotation of the cylinder block 20 (intake stroke), the suction port 30 of the cylinder bore 25 in which the piston 26 is fitted into the window 38. The fluid in the suction passage 29 is sucked into the cylinder bore 25 via the outlet 292, the window 38 and the suction port 30.

  That is, the plurality of suction ports 30 are formed in the fitting inner peripheral surface 24 of the cylinder block 20 so as to intermittently communicate with the window 38 according to the rotation angle of the cylinder block 20. Further, the plurality of suction ports 30 communicate intermittently with the introduction paths 56 and 57 according to the rotation angle of the cylinder block 20.

  As shown in FIG. 11A, a flat guide surface 58 is formed on the fitting outer peripheral surface 23 of the fixed shaft 16 in parallel with the virtual plane H on the discharge stroke corresponding region Pd side, and the suction stroke corresponding region Ps. On the side, a flat guide surface 59 is formed in parallel with the virtual plane H on the fitting outer peripheral surface 23 of the fixed shaft 16. The guide surface 58 and the guide surface 59 are parallel to each other.

  A flat guided surface 60 is formed on the inner peripheral surface 515 of the suction side valve body 51 on the discharge stroke corresponding region Pd side so as to face the guide surface 58, and on the suction stroke corresponding region Ps side, the suction side valve body is formed. A flat guided surface 61 is formed on the inner peripheral surface 515 of 51 so as to face the guide surface 59. The guided surface 60 and the guided surface 61 are parallel to each other.

  The radius of curvature of the circumferential surface of the fitting outer peripheral surface 23 of the fixed shaft 16 is smaller than the radius of curvature of the circumferential surface of the inner circumferential surface 515 of the suction side valve body 51, and the guide surfaces 58 and 59 are The guide surfaces 60 and 61 are slidably guided. That is, the suction side valve body 51 can slide in the direction of the arrow Q. The guide surfaces 58 and 59 and the guided surfaces 60 and 61 allow the suction side valve body 51 to move in the direction perpendicular to the rotation axis 131 and in the direction of the arrow Q.

  FIG. 13A shows a developed view of the fitting inner peripheral surface 24 of the cylinder block 20 and the inner peripheral surface 522 of the discharge side valve body 52. FIG. 13B is a development view of the fitting outer peripheral surface 23 of the fixed shaft 16 and the outer peripheral surfaces of the suction side valve body 51 (the large diameter outer peripheral surface 511 and the small diameter outer peripheral surface 512). The discharge side valve body 52 is disposed at a position where the suction port 30 can be closed. The suction port 30 is intermittently closed by the discharge side valve body 52 according to the rotation angle of the cylinder block 20.

  Since there is a radial clearance in the spline connection between the rotary shaft 13 and the cylinder block 20 and a radial clearance in the radial bearing 18, the cylinder block 20 is movable in the radial direction. However, the pressure in the back pressure chamber 55 is such that a load in a direction [direction T perpendicular to the direction Q] from the suction stroke corresponding region Ps side to the discharge stroke corresponding region Pd side is applied to the cylinder block via the discharge side valve body 52. 20 and a load in a direction from the discharge stroke corresponding region Pd side to the suction stroke corresponding region Ps side is applied to the cylinder block 20 via the suction side valve body 51. Since the load in the direction from the suction stroke corresponding area Ps to the discharge stroke corresponding area Pd is equal to the load in the direction from the discharge stroke corresponding area Pd to the suction stroke corresponding area Ps, the cylinder block 20 does not move in a direction orthogonal to the direction Q, and the cylinder block 20 is not tilted by this movement.

In the fifth embodiment, the same effects as the items (5) and (6) in the first embodiment are obtained, and the following effects are obtained.
(7) The cam action received from the cam surface 191 of the cam body 19 attempts to move the cylinder block 20 in the direction Q from one of the top dead center corresponding part Ht and the bottom dead center corresponding part Hd to the other. The suction side valve body 51 and the discharge side valve body 52 are pressed against the fitting inner peripheral surface 24 of the cylinder block 20 by the back pressure of the back pressure chamber 55, but the suction side valve body 51 moves in the direction of the arrow Q. Since it is slidable, the cylinder block 20 moves in the direction of the arrow Q. Since this movement is a parallel movement in the radial direction, the cylinder block 20 does not tilt. Accordingly, fluid leakage is suppressed.

  (8) The cylinder block 20 is urged in the direction T from the suction stroke corresponding region Ps side to the discharge stroke corresponding region Pd side by the fluid pressure in the cylinder bore 25 on the discharge stroke corresponding region Pd side.

  The suction side valve body 51 interposed between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20 is on the suction stroke corresponding region Ps side by the back pressure in the back pressure chamber 55. Pressed against the cylinder block 20. This back pressure opposes the fluid pressure to move the cylinder block 20 from the suction stroke corresponding region Ps side to the discharge stroke corresponding region Pd side. Accordingly, the movement of the cylinder block 20 is restricted, and an increase in the clearance between the fitting inner peripheral surface 24 of the cylinder block 20 and the discharge side valve body 52 on the discharge stroke corresponding region Pd side is suppressed, and the discharge stroke corresponding region Pd side The fluid in the cylinder bore 25 is prevented from leaking from the suction port 30 between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20. Further, there is no gap between the end surface 201 of the cylinder block 20 and the end surface 211 of the valve plate 21, and fluid leakage from between the end surfaces 201 and 211 is prevented.

  (9) The outer peripheral surface 521 of the discharge side valve body 52 is pressed against the fitting outer peripheral surface 23 of the cylinder block 20 on the discharge stroke corresponding region Pd side by the back pressure in the back pressure chamber 55. Therefore, the fluid in the cylinder bore 25 on the discharge stroke corresponding region Pd side is prevented from leaking from the suction port 30 between the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20. The

  (10) The large-diameter outer peripheral surface 511 of the suction side valve body 51 is pressed against the fitting outer peripheral surface 23 of the cylinder block 20 on the suction stroke corresponding region Ps side by the back pressure in the back pressure chamber 55. Therefore, the fluid in the cylinder bore 25 on the suction stroke corresponding region Ps side is prevented from leaking from the suction port 30 along the fitting outer peripheral surface 23 of the fixed shaft 16 and the fitting inner peripheral surface 24 of the cylinder block 20. The

  (11) The back pressure chamber 55 is a single common back pressure chamber serving as both a suction side back pressure chamber and a discharge side back pressure chamber. Such a common configuration contributes to simplification of the configuration of the suction side biasing unit and the discharge side biasing unit.

  (12) In the back pressure chamber 55 serving as both the suction side back pressure chamber and the discharge side back pressure chamber, the back pressure area for the suction side valve body 51 and the back pressure area for the discharge side valve body 52 are equal. The area is set to be larger than the passage sectional area of the suction ports 30 of all the cylinder bores 25 on the discharge stroke corresponding region Pd side. As a result, the influence of the load for moving the cylinder block 20 from the suction stroke corresponding region Ps side to the discharge stroke corresponding region Pd side by the fluid pressure in the cylinder bore 25 on the discharge stroke corresponding region Pd side is reduced. Is reliably prevented from moving.

(13) The configuration in which the introduction passages 56 and 57 are provided in the discharge-side valve body 52 is a simple configuration for introducing the discharge pressure into the back pressure chamber 55.
(14) The back pressure in the back pressure chamber 55 acts equally on the inner peripheral surface 522 of the discharge side valve body 52. Therefore, the back pressure in the back pressure chamber 55 is a biasing force suitable for evenly pressing the outer peripheral surface 521 of the discharge side valve body 52 against the fitting inner peripheral surface 24, and the back pressure chamber into which the discharge pressure is introduced. 55 is simple as a biasing means for biasing the discharge side valve body 52.

  (15) The back pressure chamber 55 is simply formed by providing an annular seal ring 54 between the fitting outer peripheral surface 23 of the fixed shaft 16 and the outer peripheral surface 521 of the discharge side valve body 52. The seal ring 54 is simple as a member for forming the back pressure chamber 55.

  (16) The guide surfaces 58 and 59 and the guided surfaces 60 and 61 allow the suction side valve body 51 to move in a direction perpendicular to the rotation center of the cylinder block 20 (that is, the rotation axis 131), and This is simple as a mechanism for preventing rotation of the suction side valve body 51 with respect to the fixed shaft 16.

  (17) The concave / convex fitting mechanism in which the discharge side valve body 52 is fitted between the steps 513 and 514 of the suction side valve body 51 allows the discharge side valve body 52 to move in a direction perpendicular to the rotation axis 131. In addition, the mechanism is simple as a mechanism for preventing the discharge side valve body 52 from rotating relative to the fixed shaft 16.

In the present invention, the following embodiments are also possible.
In the first embodiment, the guide surfaces 58 and 59 in the fifth embodiment are provided on the fitting outer peripheral surface 23 of the fixed shaft 16, and the guided surfaces 60 and 61 in the fifth embodiment are provided on the valve body 34. May be.

In the fifth embodiment, the discharge pressure introduced into the back pressure chamber 55 may be derived from the fitting inner peripheral surface 24 from the discharge passage 31 through the fixed shaft 16.
A discharge passage may be provided in the fixed shaft 16 so that the suction port 30 that is a communication port intermittently communicates with the discharge passage. In this case, the suction port 30 also serves as a discharge port, and the discharge port 32 is unnecessary.

  The fixed shaft 16 and the base housing 11 may be formed separately.

A side sectional view showing an axial piston pump of a 1st embodiment. AA sectional view taken on the line AA of FIG. FIG. 3 is a sectional view taken along line BB in FIG. 1. The CC sectional view taken on the line of FIG. FIG. (A) is a development view of the inner peripheral surface 24 of the fitting inner peripheral surface 24 of the cylinder block 20 and the cylindrical valve body 34. FIG. 4B is a development view of the outer peripheral surface of the fitting outer peripheral surface 23 of the fixed shaft 16 and the cylindrical valve body 34. Sectional drawing which shows 2nd Embodiment. Sectional drawing which shows 3rd Embodiment. Sectional drawing which shows 4th Embodiment. The sectional side view which shows the axial piston pump of 5th Embodiment. (A) is the DD sectional view taken on the line of FIG. (B) is a partial expanded sectional view. FIG. (A) is a development view of the fitting inner peripheral surface 24 of the cylinder block 20 and the inner peripheral surface of the discharge side valve body 52. FIG. 6B is a development view of the outer peripheral surface of the fitting outer peripheral surface 23 of the fixed shaft 16 and the suction side valve body 51.

Explanation of symbols

  11 ... Base housing. 122 ... An inner peripheral surface as a fixed surface. 131: A rotational axis. 15 ... Base surface. 16: Fixed shaft. 19 ... Cam body. 191: Cam surface. 20 ... Cylinder block. 201: End face. 21 ... Valve plate. 23: Fitting outer peripheral surface. 24 ... fitting inner peripheral surface. 25 ... Cylinder bore. 26 ... Piston. 29: A suction passage as a fluid passage. 30: An inlet as a communication port. 34 ... Valve body. 37, 42 ... keys. 38 ... Window. 39, 52: Discharge side valve body. 44, 46 ... Plain bearings. 48, 51 ... suction side valve element. 49, 50 ... concave portion. Ht: Top dead center corresponding part. Hd: Bottom dead center corresponding part. Pd: Discharge stroke corresponding area. Ps: Inhalation stroke area.

Claims (8)

A cylinder block that is rotatably fitted to a fixed shaft rotates about the fixed shaft, and the fixed shaft protrudes from a base housing that faces an end surface of the cylinder block, and is formed on the cylinder block. A piston is accommodated in the cylinder bore so as to be able to reciprocate, and the piston receives a cam action from the cam body due to the rotation of the cylinder block and reciprocates, and fluid is sucked into the cylinder bore as the piston returns. In the axial piston pump in which the fluid in the cylinder bore is discharged as the piston moves forward,
A fluid passage formed in the fixed shaft;
A communication port formed on a fitting inner peripheral surface of the cylinder block so as to communicate with the cylinder bore and intermittently communicate with the fluid passage according to a rotation angle of the cylinder block;
A valve element interposed between the fitting outer peripheral surface of the fixed shaft and the fitting inner peripheral surface of the cylinder block;
Rotation prevention means for preventing rotation of the valve body with respect to the fixed shaft,
The valve body is in a direction perpendicular to the rotation axis of the cylinder block and extending from at least one of the cam body top dead center corresponding portion and the cam body bottom dead center corresponding portion to the other direction. An axial piston pump that is allowed to move.   2. The axial according to claim 1, further comprising movement restriction means for restricting movement of the cylinder block in a direction orthogonal to a direction from one of the top dead center corresponding part and the bottom dead center corresponding part toward the other. Piston pump.   The movement restricting means includes a fitting inner peripheral surface of the cylinder block on the suction stroke corresponding region side and a fitting outer peripheral surface of the fixed shaft, or an outer peripheral surface of the cylinder block on the discharge stroke corresponding region side, 3. A plain bearing interposed between a fixed surface facing the outer peripheral surface, and the plain bearing allows movement of the cylinder block in a direction perpendicular to a rotation axis of the cylinder block. An axial piston pump described in 1.   The rotation preventing means is a key fitting mechanism or an uneven fitting mechanism provided between the valve body and the fitting outer peripheral surface of the fixed shaft, and the key fitting mechanism or the uneven fitting mechanism is The axial piston pump according to any one of claims 1 to 3, wherein the valve body is allowed to move in a direction perpendicular to a rotation axis of the cylinder block.   The valve body is a cylindrical valve body surrounding the fixed shaft, and the valve body communicates with the fluid passage and intermittently communicates with the communication port according to the rotation angle of the cylinder block. The axial piston pump according to any one of claims 1 to 4, further comprising a window.   The axial piston pump according to claim 5, wherein the fluid passage is a suction passage, and the window intermittently communicates with the communication port in a suction stroke corresponding region according to a rotation angle of the cylinder block.   The valve body is fixed to the fitting inner peripheral surface of the cylinder block on the discharge stroke corresponding region side and the fixed portion so as to intermittently block the communication port of the discharge stroke corresponding region according to the rotation angle of the cylinder block. The axial piston pump according to any one of claims 1 to 4, wherein the axial piston pump is a discharge-side valve element interposed between a fitting outer peripheral surface of the shaft. A discharge passage formed in the base housing and a discharge port formed in the end face of the cylinder block so as to communicate with the cylinder bore and intermittently communicate with the discharge passage according to a rotation angle of the cylinder block With
A valve plate is interposed between the base surface of the base housing and the end surface of the cylinder block,
The discharge passage includes an arc-shaped discharge connection port extending in a circumferential direction of the fixed shaft along a base surface of the base housing facing the end surface of the cylinder block, and the discharge connection port includes the valve The axial piston pump according to claim 1, wherein the axial piston pump is formed on the valve plate so as to penetrate the plate.

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