EP4703587A1

EP4703587A1 - Hydraulic rotary machine

Info

Publication number: EP4703587A1
Application number: EP24796867.0A
Authority: EP
Inventors: Tetsuya Iwanaji
Original assignee: KYB Corp
Current assignee: KYB Corp
Priority date: 2023-04-28
Filing date: 2024-04-16
Publication date: 2026-03-04
Also published as: WO2024225114A1; JPWO2024225114A1; CN120958234A

Abstract

A pump (100) includes: a cylinder block (30) configured to rotate together with a shaft (20); a piston (36) that is slidably inserted into a cylinder (31) formed in the cylinder block (30); a port block (50) having a first port (41) through which a working fluid supplied to a capacity chamber (32) flows and a second port (45) through which a working fluid discharged from the capacity chamber (32) flows; a cam ring (60) having a cam surface (61); and a capacity changing unit (70) configured to change an amount of the working fluid guided into the capacity chamber (32) by causing the port block (50) to rotate about a rotation center axis (C1) and changing a relative positional relation between the port block (50) and the cam ring (60).

Description

TECHNICAL FIELD

The present invention relates to a hydraulic rotating machine.

BACKGROUND ART

JP2009-121420A discloses a variable capacity type radial piston pump that changes a capacity of the radial piston pump by sliding a cam ring in an axial direction.

SUMMARY OF INVENTION

In a case where the cam ring disposed on an outer side in a radial direction is caused to slide along the axial direction in order to make the capacity of the pump variable as in the radial piston pump disclosed in JP2009-121420A , it is necessary to ensure a space that allows movement of the cam ring in the axial direction, and a mechanism for moving the cam ring is disposed on the outer side in the radial direction of the cam ring. Therefore, the entire pump may be increased in size in the axial direction and the radial direction.
An object of the present invention is to make a variable capacity type hydraulic rotating machine compact.
According to one aspect of the present invention, a variable capacity type hydraulic rotating machine, includes: a housing; a cylinder block accommodated in the housing and configured to rotate together with a shaft; a plurality of cylinders formed radially in the cylinder block about a rotation center axis of the shaft; a plurality of pistons slidably inserted into the cylinders and defining respective capacity chambers inside the cylinders; a port block having a first port through which a working fluid supplied to the capacity chamber flows and a second port through which a working fluid discharged from the capacity chamber flows, and disposed in the housing so as to be in sliding contact with the cylinder block; a cam ring having a cam surface with which a tip of the piston comes into contact as the cylinder block rotates; and a capacity changing unit configured to change an amount of the working fluid guided into the capacity chamber by causing at least one of the port block and the cam ring to rotate about the rotation center axis and changing a relative positional relation between the port block and the cam ring.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a sectional view of a hydraulic rotating machine according to an embodiment of the present invention.
[FIG. 2] FIG. 2 is a sectional view taken along a line II-II in FIG. 1.
[FIG. 3] FIG. 3 is a sectional view taken along a line III-III in FIG. 1.
[FIG. 4] FIG. 4 is a diagram illustrating a state in which an amount of a working fluid guided into a capacity chamber is maximum in order of processes.
[FIG. 5] FIG. 5 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is maximum in order of processes, and is a diagram illustrating a state subsequent to FIG. 4.
[FIG. 6] FIG. 6 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is maximum in order of processes, and is a diagram illustrating a state subsequent to FIG. 5.
[FIG. 7] FIG. 7 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is maximum in order of processes, and is a diagram illustrating a state subsequent to FIG. 6.
[FIG. 8] FIG. 8 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is maximum in order of processes, and is a diagram illustrating a state subsequent to FIG. 7.
[FIG. 9] FIG. 9 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is minimum in order of processes.
[FIG. 10] FIG. 10 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is minimum in order of processes, and is a diagram illustrating a state subsequent to FIG. 9.
[FIG. 11] FIG. 11 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is minimum in order of processes, and is a diagram illustrating a state subsequent to FIG. 10.
[FIG. 12] FIG. 12 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is minimum in order of processes, and is a diagram illustrating a state subsequent to FIG. 11.
[FIG. 13] FIG. 13 is a diagram illustrating a state in which the amount of the working fluid guided into the capacity chamber is minimum in order of processes, and is a diagram illustrating a state subsequent to FIG. 12.
[FIG. 14] FIG. 14 is a diagram for illustrating a case where the amount of the working fluid guided into the capacity chamber is maximum and a case where the amount of the working fluid guided into the capacity chamber is minimum.
[FIG. 15] FIG. 15 is a sectional view of a modification of the hydraulic rotating machine according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a hydraulic rotating machine according to an embodiment of the present invention will be described with reference to the drawings.
As illustrated in FIG. 1, the hydraulic rotating machine according to the embodiment of the present invention is a variable capacity type radial piston pump motor 100, which functions as a pump capable of supplying a working fluid by causing a shaft 20 to rotate by power from the outside and a piston 36 to reciprocate, and functions as a motor capable of outputting a rotation driving force by causing the piston 36 to reciprocate by a fluid pressure of the working fluid supplied from the outside and the shaft 20 to rotate. As the working fluid, water, oil, an aqueous alternative fluid, or the like is used, but the working fluid is not limited thereto. FIG. 1 is a sectional view illustrating a section of the radial piston pump motor 100, FIG. 2 is a sectional view taken along a line II-II of FIG. 1, and FIG. 3 is a sectional view taken along a line III-III of FIG. 1.
In the following description, a case where the radial piston pump motor 100 functions as a pump is exemplified, and the radial piston pump motor 100 is simply referred to as the "pump 100".
The pump 100 is mounted on a vehicle such as construction equipment, for example, and is used as a working fluid supply source that supplies a working fluid to a fluid pressure actuator or the like by rotationally driving the shaft 20 by power of an engine or an electric motor mounted on the vehicle.
As illustrated in FIG. 1, the pump 100 includes: a housing 10; a shaft 20 rotatably supported by the housing 10; a cylinder block 30 accommodated in the housing 10 and configured to rotate about a rotation center axis C1 together with the shaft 20; a plurality of cylinders 31 formed in the cylinder block 30; a plurality of pistons 36 slidably inserted into the cylinders 31 and defining respective capacity chambers 32 inside the cylinders 31; a port block 50 having a suction port 41 serving as a first port through which a working fluid supplied to the capacity chamber 32 flows and a discharge port 45 serving as a second port through which a working fluid discharged from the capacity chamber 32 flows; and a cam ring 60 having a cam surface 61 with which the piston 36 comes into contact as the cylinder block 30 rotates.
The housing 10 includes a housing main body 11 in which an accommodation recess 13 in which the shaft 20, the cylinder block 30, the port block 50, and the cam ring 60 are accommodated is formed; and a housing cover 12 that seals an opening end of the housing main body 11 and in which a through hole 12a through which the shaft 20 is inserted is formed.
The accommodation recess 13 is provided with a first accommodation recess 14 in which a tip portion 21 of the shaft 20 is accommodated, a second accommodation recess 15 in which the port block 50 is accommodated, a third accommodation recess 16 in which the cylinder block 30 is accommodated, and a fourth accommodation recess 17 in which the cam ring 60 is accommodated, in this order from a bottom portion side of the accommodation recess 13 along a direction of the rotation center axis C1.
A bottom portion of the first accommodation recess 14 may be opened to attach an auxiliary pump or rotation sensor (not illustrated) to the tip portion 21 of the shaft 20 without being closed. In addition, a space for accommodating the cylinder block 30 is formed not only on a housing main body 11 side but also on a housing cover 12 side.
As illustrated in FIGS. 1 and 3, the housing main body 11 is formed with a suction passage 43 through which a working fluid supplied from a tank (not illustrated) or an auxiliary pump (not illustrated) flows, and a connection passage 42 that connects a plurality of suction ports 41 formed in the port block 50 to the suction passage 43, and is formed with a discharge passage 47 through which a working fluid discharged from the capacity chamber 32 and directed toward a working fluid pressure device (not illustrated) flows. In addition, the housing main body 11 is formed with an accommodation portion 75 in which a capacity changing unit 70 to be described later is accommodated.
The shaft 20 is rotatably supported by the housing main body 11 via a first bearing 25 provided in the first accommodation recess 14, and is rotatably supported by the housing cover 12 via a second bearing 26. A coupling portion 22 to which a power source (not illustrated) for driving the pump 100 is coupled is formed on an end portion of the shaft 20 protruding to the outside through the through hole 12a of the housing cover 12.
On an outer peripheral surface of the shaft 20 between the first bearing 25 and the second bearing 26, a spline shaft portion 23 that is splined to a spline hole portion 35 to be described later formed in the cylinder block 30 is formed.
As illustrated in FIGS. 1 and 2, the cylinder block 30 is an annular member in which a through hole through which the shaft 20 is inserted is provided in the center, and includes the plurality of cylinders 31 formed radially around the rotation center axis C1, a communication hole 33 capable of allowing the cylinders 31 to communicate with the suction port 41 and the discharge port 45, and the spline hole portion 35 formed on an inner peripheral surface of the through hole through which the shaft 20 is inserted.
As illustrated in FIG. 2, the plurality of cylinders 31 formed radially around the rotation center axis C1 are disposed at equal intervals in a circumferential direction, and the piston 36 defining the capacity chamber 32 inside the cylinder 31 is slidably inserted into each cylinder 31. Although FIG. 2 illustrates an example in which the cylinders 31 are provided at eight positions, the number of the cylinders 31 installed is not limited thereto, and may be more than eight or less than eight.
The communication hole 33 is formed along the direction of the rotation center axis C1 such that one end thereof opens in a bottom portion of the cylinder 31 and the other end thereof opens in a sliding contact surface 34 formed on a side surface of the cylinder block 30. The sliding contact surface 34 in which the communication hole 33 is open is a surface that is in sliding contact with a sliding contact surface 55 (described later) of the port block 50 when the cylinder block 30 rotates.
The piston 36 includes a columnar portion 37 inserted into the cylinder 31 and a spherical body 38 provided on an end portion of the columnar portion 37. A hole formed in a concave spherical shape for holding the spherical body 38 is formed on one end side of the columnar portion 37, and the spherical body 38 is rotatably held by the columnar portion 37 by drawing (caulking) an opening end portion of the columnar portion 37 from an outer side in a radial direction in a state in which more than half of the spherical body 38 is accommodated in the hole. In addition, the piston 36 has a configuration capable of supplying the working fluid in the capacity chamber 32 to a surface of the spherical body 38 as a lubricant.
Since a centrifugal force generated in response to the rotation of the cylinder block 30 acts on the piston 36 inserted into the cylinder 31, the spherical body 38 located at the most tip of the piston 36 protruding from an opening end of the cylinder 31 is in a state of being pressed against the cam surface 61 of the cam ring 60. Therefore, the spherical body 38 functions as a transmission portion that causes the piston 36 to reciprocate according to a profile of the cam surface 61. In order to bring the spherical body 38 into a state of being normally pressed against the cam surface 61 of the cam ring 60, a spring for biasing the piston 36 toward the outer side in the radial direction may be installed in the cylinder 31.
The cam ring 60 is an annular member having the cam surface 61 formed on an inner peripheral surface thereof, and is sandwiched between the housing main body 11 and the housing cover 12 by attaching and fixing the housing cover 12 to the housing main body 11 in a state of being accommodated in the fourth accommodation recess 17.
As illustrated in FIG. 2, a shape of the cam surface 61 in the circumferential direction is a shape having a cam profile in which a plurality of top dead centers that maximize an insertion amount of the piston 36 into the cylinder 31 and a plurality of bottom dead centers that minimize the insertion amount of the piston 36 into the cylinder 31 are alternately provided.
An arc-shaped groove formed in accordance with a curvature of the spherical body 38 is provided along the circumferential direction on the surface of the cam surface 61. Therefore, the spherical body 38 rotatably provided on the piston 36 smoothly moves while rolling on the cam surface 61 without coming off the cam surface 61.
A shape of a portion of the piston 36 in contact with the cam surface 61 is not limited to the spherical body 38 as described above, and may be, for example, a convex spherical portion directly formed on the end portion of the columnar portion 37 or a cylindrical body rotatably held by the columnar portion 37. However, in order to reduce a contact resistance between the piston 36 and the cam surface 61, the spherical body 38 as described above is preferable.
The port block 50 is a cylindrical member having a through hole 51 through which the shaft 20 is inserted, a sliding contact surface 55 that is in surface contact with the sliding contact surface 34 of the cylinder block 30, and a plurality of suction ports 41 and discharge ports 45 that are open at one end in the sliding contact surface 55.
The port block 50 is pressed toward the cylinder block 30 by a biasing force of a spring 58 disposed in the accommodation recess 13 such that the sliding contact surface 55 in which the suction port 41 and the discharge port 45 open is in a state of being normally in surface contact with the sliding contact surface 34 of the cylinder block 30. Thus, the port block 50 is disposed in the housing 10 so as to be in sliding contact with the rotating cylinder block 30.
The second accommodation recess 15 in which the port block 50 is accommodated includes a small-diameter recess 15a and a large-diameter recess 15b having an inner diameter larger than that of the small-diameter recess 15a, and in correspondence to this, the port block 50 is provided with a small-diameter portion 52a accommodated in the small-diameter recess 15a and a large-diameter portion 52b having an outer diameter larger than that of the small-diameter portion 52a and accommodated in the large-diameter recess 15b.
An annular space 46 communicating with the discharge passage 47 is formed between the port block 50 and the second accommodation recess 15 formed as described above, specifically, between a step portion connecting the small-diameter recess 15a and the large-diameter recess 15b and a step portion connecting the small-diameter portion 52a and the large-diameter portion 52b. An O-ring 53a provided in the small-diameter portion 52a and an O-ring 53b provided in the large-diameter portion 52b prevent a working fluid from flowing into the annular space 46 and a working fluid from flowing out of the annular space 46 through a gap between the small-diameter recess 15a and the small-diameter portion 52a and a gap between the large-diameter recess 15b and the large-diameter portion 52b.
A plurality of the suction ports 41 are formed in the port block 50 such that one end thereof opens in the sliding contact surface 55 and the other end thereof is connected to the connection passage 42, and a plurality of the discharge ports 45 are formed in the port block 50 such that one end thereof opens in the sliding contact surface 55 and the other end thereof opens in the annular space 46.
Opening positions of the suction port 41 and the discharge port 45 in the sliding contact surface 55 are set to be alternately located at equal intervals in the circumferential direction as illustrated in FIG. 2. That is, the suction port 41 and the discharge port 45 are provided so as to alternately communicate with the communication hole 33 in response to the rotation of the cylinder block 30. In FIG. 2, the suction port 41 is indicated by a one-dot chain line, and the discharge port 45 is indicated by a two-dot chain line. In FIG. 2, some of the suction ports 41 and the discharge ports 45 are in a state of overlapping with the communication hole 33.
As illustrated in FIG. 3, the connection passage 42 to which the other end of the suction port 41 is connected is not formed in an annular shape. Therefore, some of the suction ports 41 are formed in the port block 50 with a three-dimensional curved path. Further, as will be described later, an opening position of the other end of each suction port 41 is appropriately set according to a maximum rotation amount of the port block 50 such that the state in which the other end of the suction port 41 is connected to the connection passage 42 is maintained even in a case where the port block 50 rotates about the rotation center axis C1.
The pump 100 having the above-described configuration further includes a capacity changing unit 70 configured to change an amount of the working fluid guided into each capacity chamber 32 as a mechanism for changing a discharge amount.
The capacity changing unit 70 illustrated in FIGS. 1 and 3 changes a relative positional relation between the port block 50 and the cam ring 60 about the rotation center axis C1 by causing the port block 50 to rotate about the rotation center axis C1, and specifically, the capacity changing unit 70 changes the positions of the suction port 41 and the discharge port 45 with respect to the cam surface 61 about the rotation center axis C1. The capacity changing unit 70 may cause the cam ring 60 to rotate about the rotation center axis C1 as to be described later.
The capacity changing unit 70 includes a rod-shaped control pin 71 having one end rotatably inserted into a hole formed in an end surface of the small-diameter portion 52a of the port block 50, a control piston 72 capable of pressing the control pin 71 along a direction orthogonal to the rotation center axis C1, a control pressure chamber 73 formed on a side opposite to the control pin 71 across the control piston 72, and a control spring 74 for biasing the control pin 71 toward the control piston 72.
The control pin 71 is installed in such a manner that the control pin 71 passes from a bottom portion of the second accommodation recess 15 through a first accommodation hole 75a formed along the direction of the rotation center axis C1 and a tip portion thereof enters a second accommodation hole 75b in which the control piston 72 and the control spring 74 are accommodated. As illustrated in FIG. 3, the second accommodation hole 75b is formed along the direction orthogonal to the rotation center axis C1.
As illustrated in FIG. 3, the tip portion of the control pin 71 protruding into the second accommodation hole 75b has a shape having two flat surfaces parallel to each other, a pressing force of the control piston 72 acts on one of the flat surfaces, and a biasing force of the control spring 74 acts on the other of the flat surfaces. In other words, the pressing force of the control piston 72 and the biasing force of the control spring 74 act on the port block 50 via the control pin 71.
The capacity changing unit 70 further includes a control valve (not illustrated) that controls the working fluid to flow into and out of the control pressure chamber 73.
When the working fluid is supplied to the control pressure chamber 73 through the control valve, a pressure of the working fluid acts on the control piston 72, and the control piston 72 presses the control pin 71 in accordance with the pressure of the working fluid in the control pressure chamber 73. When the pressing force of the control piston 72 against the control pin 71 exceeds the biasing force of the control spring 74, the control pin 71 moves in a direction of expanding the control pressure chamber 73 together with the control piston 72. Accordingly, the port block 50 rotates about the rotation center axis C1 in a direction in which the control pin 71 moves.
On the other hand, when the working fluid is discharged from the control pressure chamber 73 through the control valve, the control pin 71 moves in a direction in which the control pressure chamber 73 contracts due to the biasing force of the control spring 74. Accordingly, the port block 50 rotates about the rotation center axis C1 in the direction in which the control pin 71 moves.
As described above, the control piston 72, the control pressure chamber 73, and the control spring 74 function as a load applying unit configured to apply a load for causing the port block 50 to rotate about the rotation center axis C1 to the port block 50 via the control pin 71, and a rotation amount of the port block 50 is adjusted to any magnitude by changing the pressure of the working fluid supplied to the control pressure chamber 73. For example, the magnitude of the pressure in the control pressure chamber 73 and a position of the control piston 72 may be detected by a sensor (not illustrated), and the rotation amount of the port block 50 may be adjusted to a target value by controlling the control valve according to the detected value.
As illustrated in FIG. 2, in a case where the piston 36 reciprocates six times during one rotation of the cylinder block 30, a maximum rotation amount (required maximum rotation angle) of the port block 50 required for changing the amount of the working fluid guided into the capacity chamber 32 is about 15°. The maximum rotation amount of the port block 50, that is, a maximum movement amount (required maximum stroke) of the control piston 72 that causes the port block 50 to rotate via the control pin 71 is increased as the number of times the piston 36 reciprocates during one rotation of the cylinder block 30 is reduced, and is reduced as the number of times the piston 36 reciprocates during one rotation of the cylinder block 30 is increased.
The load applying unit configured to apply the load for causing the port block 50 to rotate to the port block 50 via the control pin 71 is not limited to a load applying unit using the pressure of the fluid supplied to the control pressure chamber 73 and the biasing force of the control spring 74 as described above, and may be, for example, an electric linear actuator capable of moving the control pin 71 along the direction orthogonal to the rotation center axis C1. A rotation mechanism that causes the port block 50 to rotate is not limited to a mechanism having the above-described configuration, and may be any mechanism as long as the mechanism can cause the port block 50 to rotate about the rotation center axis C1 by a predetermined amount, and for example, a rack gear formed in an arc shape on the small-diameter portion 52a of the port block 50, a pinion gear that meshes with the rack gear, and a stepping motor that rotationally drives the pinion gear may be used.
As illustrated in FIG. 1, the capacity changing unit 70 is disposed on a side opposite to the cylinder block 30 across the port block 50 in the axial direction of the rotation center axis C1. Therefore, even in a case where the capacity changing unit 70 is provided to make the pump 100 of a variable capacity type, an increase in size of the pump 100 in the radial direction can be suppressed.
Next, with reference to FIGS. 4 to 13, a description will be given of a mechanism in which an amount of the working fluid guided into each capacity chamber 32, that is, an amount of the working fluid sucked into each capacity chamber 32 and discharged from each capacity chamber 32 is changed when the capacity changing unit 70 having the above-described configuration is caused to operate to change the relative positional relation between the port block 50 and the cam ring 60 around the rotation center axis C1.
FIGS. 4 to 13 illustrate sections corresponding to the section illustrated in FIG. 2, FIGS. 4 to 8 are views illustrating states in which the amount of the working fluid guided into each capacity chamber 32 is maximum in order of processes, and FIGS. 9 to 13 are views illustrating states in which the amount of the working fluid guided into each capacity chamber 32 is minimum in order of processes. Although only movement of one piston 36 with respect to the cam surface 61 of the cam ring 60 is illustrated in FIGS. 4 to 13, movement of other pistons 36 is the same.
First, a case where the amount of the working fluid discharged from each capacity chamber 32 is maximum, that is, a case where the discharge amount of the pump 100 is maximum will be described with reference to FIGS. 4 to 8.
In order to maximize the amount of the working fluid discharged from each capacity chamber 32, the suction ports 41 and the discharge ports 45 are in an open state at intermediate positions between the top dead centers and the bottom dead centers of the cam surface 61, respectively, as illustrated in FIG. 4 when the port block 50 is caused to rotate to a position set in advance by the capacity changing unit 70.
Specifically, when viewed along a rotation direction of the cylinder block 30 indicated by an arrow R in FIG. 4, the relative positional relation between the port block 50 and the cam ring 60 about the rotation center axis C1 is set by the capacity changing unit 70 such that the suction port 41 is located at an intermediate position between the top dead center and the bottom dead center of the cam surface 61 and the discharge port 45 is located at an intermediate position between the bottom dead center and the top dead center of the cam surface 61.
Note that "the suction port 41 is located at an intermediate position between the top dead center and the bottom dead center of the cam surface 61" means that an opening center of the suction port 41 is located on a bisector equally dividing an angle formed by a line connecting the top dead center of the cam surface 61 and the rotation center axis C1 and a line connecting the bottom dead center of the cam surface 61 and the rotation center axis C1, and a phase difference between the suction port 41 and the top dead center in the circumferential direction and a phase difference between the suction port 41 and the bottom dead center in the circumferential direction are the same, and "the discharge port 45 is located at an intermediate position between the bottom dead center and the top dead center of the cam surface 61" means that an opening center of the discharge port 45 is located on a bisector equally dividing an angle formed by a line connecting the bottom dead center of the cam surface 61 and the rotation center axis C1 and a line connecting the top dead center of the cam surface 61 and the rotation center axis C1, and a phase difference between the discharge port 45 and the bottom dead center in the circumferential direction and a phase difference between the discharge port 45 and the top dead center in the circumferential direction are the same.
Accordingly, in a state in which the relative positional relation between the port block 50 and the cam ring 60 is set, when the cylinder block 30 rotates in the direction indicated by the arrow R, the suction port 41 and the communication hole 33 start to communicate with each other, and a suction process in which the working fluid can be sucked into the capacity chamber 32 through the suction port 41 is started.
The suction process passes through a state in which the communication hole 33 and the suction port 41 completely communicate with each other as illustrated in FIG. 5, and is continued until the communication between the communication hole 33 and the suction port 41 is blocked as illustrated in FIG. 6.
As described above, in a case where the relative positional relation between the port block 50 and the cam ring 60 is set such that the opening position of the suction port 41 is the intermediate position between the top dead center and the bottom dead center of the cam surface 61, the piston 36 located at the top dead center starts to move toward the outer side in the radial direction along the cam surface 61 at the same time as the suction process starts.
Since the capacity chamber 32 starts to expand as the piston 36 moves toward the outer side in the radial direction, the working fluid is sucked into the capacity chamber 32 from a tank (not illustrated) through the suction port 41 communicating with the communication hole 33, the connection passage 42, and the suction passage 43.
During the suction process in which the communication hole 33 and the suction port 41 communicate with each other, the piston 36 moves from the top dead center to the bottom dead center as illustrated in FIGS. 4 to 6, and the capacity chamber 32 continues to expand as the piston 36 moves. Therefore, during the suction process, the working fluid is continuously sucked into the capacity chamber 32.
When the cylinder block 30 further rotates in the direction indicated by the arrow R from the state illustrated in FIG. 6, the discharge port 45 and the communication hole 33 start to communicate with each other, and a discharge process in which the working fluid in the capacity chamber 32 can be discharged through the discharge port 45 is started.
The discharge process passes through a state in which the communication hole 33 and the discharge port 45 are completely communicated with each other as illustrated in FIG. 7, and is continued until the communication between the communication hole 33 and the discharge port 45 is blocked as illustrated in FIG. 8.
As described above, in a case where the relative positional relation between the port block 50 and the cam ring 60 is set such that the opening position of the discharge port 45 is the intermediate position between the bottom dead center and the top dead center of the cam surface 61, the piston 36 located at the bottom dead center starts to move toward an inner side in the radial direction along the cam surface 61 at the same time as the discharge process starts.
Since the capacity chamber 32 starts to contract as the piston 36 moves toward the inner side in the radial direction, the working fluid in the capacity chamber 32 is discharged to a working fluid pressure device (not illustrated) through the discharge port 45 communicating with the communication hole 33, the annular space 46, and the discharge passage 47.
During the discharge process in which the communication hole 33 and the discharge port 45 communicate with each other, the piston 36 moves from the bottom dead center to the top dead center as illustrated in FIGS. 6 to 8, and the capacity chamber 32 continues to contract as the piston 36 moves. Therefore, during the discharge process, the working fluid is continuously discharged from the capacity chamber 32.
Accordingly, in a case where the suction ports 41 and the discharge ports 45 are in an open state at the intermediate positions between the top dead centers and the bottom dead centers of the cam surface 61, respectively, the amount of the working fluid sucked into the capacity chamber 32 through the suction port 41 in the suction process is maximum, and the amount of the working fluid discharged from the capacity chamber 32 through the discharge port 45 in the discharge process is maximum. As a result, the discharge amount of the pump 100 is maximum.
Next, a case where the amount of the working fluid discharged from each capacity chamber 32 is minimum, that is, a case where the discharge amount of the pump 100 is minimum will be described with reference to FIGS. 9 to 13.
In order to minimize the amount of working fluid discharged from each capacity chamber 32, the suction port 41 is located at the same position as the top dead center of the cam surface 61 in the circumferential direction, and the discharge port 45 is located at the same position as the bottom dead center of the cam surface 61 in the circumferential direction, as illustrated in FIG. 9 when the port block 50 is caused to rotate to the position set in advance by the capacity changing unit 70.
Specifically, when the port block 50 is caused to rotate by the capacity changing unit 70 by a predetermined angle (for example, 15°) around the rotation center axis C1 in a direction indicated by an arrow M in FIG. 9 (direction opposite to arrow R) from the state illustrated in FIG. 4, the opening center of the suction port 41 is located on the line connecting the top dead center of the cam surface 61 and the rotation center axis C1, that is, the phase difference between the suction port 41 and the top dead center in the circumferential direction is zero; and the opening center of the discharge port 45 is located on the line connecting the bottom dead center of the cam surface 61 and the rotation center axis C1, that is, the phase difference between the discharge port 45 and the bottom dead center in the circumferential direction is zero.
Note that "the suction port 41 is located at the same position as the top dead center of the cam surface 61 in the circumferential direction" means that the opening center of the suction port 41 is located on the line connecting the top dead center of the cam surface 61 and the rotation center axis C1, and "the discharge port 45 is located at the same position as the bottom dead center of the cam surface 61 in the circumferential direction" means that the opening center of the discharge port 45 is located on the line connecting the bottom dead center of the cam surface 61 and the rotation center axis C1.
Accordingly, in a state in which the relative positional relation between the port block 50 and the cam ring 60 is set, when the cylinder block 30 rotates in the direction indicated by the arrow R, the suction port 41 and the communication hole 33 start to communicate with each other, and the suction process in which the working fluid can be sucked into the capacity chamber 32 through the suction port 41 is started.
The suction process passes through a state in which the communication hole 33 and the suction port 41 completely communicate with each other as illustrated in FIG. 10, and is continued until the communication between the communication hole 33 and the suction port 41 is blocked as illustrated in FIG. 11.
Here, in a case where the suction port 41 opens at the same position as the top dead center of the cam surface 61 in the circumferential direction, that is, in a case where the phase difference between the suction port 41 and the top dead center in the circumferential direction is zero, the piston 36 moves toward the top dead center as illustrated in FIGS. 9 and 10 and then moves toward the bottom dead center as illustrated in FIGS. 10 and 11 during the suction process. Therefore, the capacity chamber 32 contracts and then expands with the movement of the piston 36 during the suction process.
Accordingly, during the suction process, the working fluid in the capacity chamber 32 is discharged through the suction port 41 while the piston 36 moves toward the top dead center, and the working fluid is sucked into the capacity chamber 32 through the suction port 41 while the piston 36 moves toward the bottom dead center.
Specifically, the working fluid is discharged from the capacity chamber 32 from when the communication hole 33 and the suction port 41 start to communicate with each other in a state in which the piston 36 moves toward the top dead center as illustrated in FIG. 9 until the piston 36 reaches the top dead center as illustrated in FIG. 10, and the working fluid is sucked into the capacity chamber 32 from when the piston 36 starts to move toward the bottom dead center in a state in which the communication hole 33 and the suction port 41 communicate with each other as illustrated in FIG. 10 until the communication between the communication hole 33 and the suction port 41 is blocked as illustrated in FIG. 11.
In other words, in one suction process, the working fluid is sucked into the capacity chamber 32 through the suction port 41 by the same amount as the amount discharged from the capacity chamber 32 through the suction port 41, and thus a substantial suction amount into the capacity chamber 32 is zero.
When the cylinder block 30 further rotates in the direction indicated by the arrow R from the state illustrated in FIG. 11, the discharge port 45 and the communication hole 33 start to communicate with each other, and the discharge process in which the working fluid in the capacity chamber 32 can be discharged through the discharge port 45 is started.
The discharge process passes through a state in which the communication hole 33 and the discharge port 45 are completely communicated with each other as illustrated in FIG. 12, and is continued until the communication between the communication hole 33 and the discharge port 45 is blocked as illustrated in FIG. 13.
Here, in a case where the discharge port 45 opens at the same position as the bottom dead center of the cam surface 61 in the circumferential direction, that is, in a case where the phase difference between the discharge port 45 and the bottom dead center in the circumferential direction is zero, the piston 36 moves toward the bottom dead center as illustrated in FIGS. 11 and 12 and then moves toward the top dead center as illustrated in FIGS. 12 and 13 during the discharge process. Therefore, the capacity chamber 32 expands and then contracts with the movement of the piston 36 during the discharge process.
Accordingly, during the discharge process, the working fluid is sucked into the capacity chamber 32 through the discharge port 45 while the piston 36 moves toward the bottom dead center, and the working fluid in the capacity chamber 32 is discharged through the discharge port 45 while the piston 36 moves toward the top dead center.
Specifically, the working fluid is sucked into the capacity chamber 32 from when the communication hole 33 and the discharge port 45 start to communicate with each other in a state in which the piston 36 moves toward the bottom dead center as illustrated in FIG. 11 until the piston 36 reaches the bottom dead center as illustrated in FIG. 12, and the working fluid is discharged from the capacity chamber 32 from when the piston 36 starts to move toward the top dead center in a state in which the communication hole 33 and the discharge port 45 communicate with each other as illustrated in FIG. 12 until the communication between the communication hole 33 and the discharge port 45 is blocked as illustrated in FIG. 13.
In other words, in one discharge process, the working fluid is discharged from the capacity chamber 32 through the discharge port 45 by the same amount as the amount of the working fluid sucked into the capacity chamber 32 through the discharge port 45, and thus a substantial discharge amount from the capacity chamber 32 is zero.
Accordingly, in a case where the suction port 41 opens at the same position as the top dead center of the cam surface 61 in the circumferential direction and the discharge port 45 opens at the same position as the bottom dead center of the cam surface 61 in the circumferential direction, the amount of the working fluid sucked into the capacity chamber 32 through the suction port 41 in the suction process is substantially zero, and the amount of the working fluid discharged from the capacity chamber 32 through the discharge port 45 in the discharge process is also substantially zero. As a result, the discharge amount of the pump 100 is substantially zero, that is, minimum.
As described above, in the case where the discharge amount of the pump 100 is maximum and minimum, a relation between a state of the capacity chamber 32 due to the movement of the piston 36 and a communication state between the capacity chamber 32 and each of the ports 41 and 45 is summarized as illustrated in FIG. 14. In FIG. 14, only one suction process and one discharge process are illustrated for convenience of description.
As illustrated in FIG. 14, the amount of the working fluid discharged from each capacity chamber 32 changes in accordance with how two periods (a suction-enabled period in which the communication hole 33 and the suction port 41 communicate with each other and the working fluid can be sucked into the capacity chamber 32, that is, a supply-enabled period in which the working fluid can be supplied into the capacity chamber 32, and a discharge-enabled period in which the communication hole 33 and the discharge port 45 communicate with each other and the working fluid in the capacity chamber 32 can be discharged) overlap with each other with respect to two periods (a contraction period in which a capacity of the capacity chamber 32 contracts, that is, a period in which the piston 36 moves from the bottom dead center toward the top dead center, and an expansion period in which the capacity of the capacity chamber 32 expands, that is, a period in which the piston 36 moves from the top dead center toward the bottom dead center). The suction-enabled period (supply-enabled period) corresponds to a period of the suction process described above, and can also be referred to as a communication state period in which the communication hole 33 and the suction port 41 are in communication with each other. In addition, the discharge-enabled period corresponds to a period of the discharge process described above, and can also be referred to as a communication state period in which the communication hole 33 and the discharge port 45 are in communication with each other.
When the discharge amount of the pump 100 is maximum, as described above, the suction ports 41 and the discharge ports 45 are in an open state at the intermediate positions between the top dead centers and the bottom dead centers of the cam surface 61, respectively, and thus the suction-enabled period overlaps with the expansion period and the discharge-enabled period overlaps with the contraction period.
On the other hand, when the discharge amount of the pump 100 is minimum, as described above, the suction port 41 opens at the same position as the top dead center of the cam surface 61 in the circumferential direction, and the discharge port 45 opens at the same position as the bottom dead center of the cam surface 61 in the circumferential direction, and thus the suction-enabled period overlaps with the contraction period and the expansion period at substantially the same ratio, and the discharge-enabled period overlaps with the expansion period and the contraction period at substantially the same ratio.
Specifically, as illustrated in FIG. 14, when a first period T1 in which the suction-enabled period and the contraction period overlap with each other and a second period T2 in which the suction-enabled period and the expansion period overlap with each other have the same length, that is, the same ratio (1:1), the amount of the working fluid discharged from the capacity chamber 32 through the suction port 41 during the suction-enabled period and the amount of the working fluid sucked into the capacity chamber 32 through the suction port 41 are substantially the same, and as a result, the amount of the working fluid discharged from each capacity chamber 32 is substantially zero, that is, minimum. In other words, the amount of the working fluid discharged from each capacity chamber 32 is maximum by setting the first period T1 in which the suction-enabled period and the contraction period overlap with each other to zero or close to zero, that is, by setting the ratio between the first period T1 and the second period T2 to 0:100.
Here, in a case where the suction port 41 and the discharge port 45 open between the position illustrated in FIG. 4 and the position illustrated in FIG. 9, respectively, in the suction process, the working fluid is discharged from the capacity chamber 32, but the amount discharged from the capacity chamber 32 through the suction port 41 is smaller than the amount sucked into the capacity chamber 32 through the suction port 41, and in the discharge process, the working fluid is sucked into the capacity chamber 32, but the amount sucked into the capacity chamber 32 through the discharge port 45 is smaller than the amount discharged from the capacity chamber 32 through the discharge port 45.
That is, the amount of the working fluid discharged from each capacity chamber 32 is changed by changing the positions where the suction port 41 and the discharge port 45 open between the position illustrated in FIG. 4 and the position illustrated in FIG. 9, and is reduced as the phase difference between the top dead center and the suction port 41 in the circumferential direction is reduced and as the phase difference between the bottom dead center and the discharge port 45 in the circumferential direction is reduced, that is, as the above-described first period T1 in which the suction-enabled period and the contraction period overlap with each other is increased.
Note that "the phase difference between the top dead center and the suction port 41 in the circumferential direction is reduced" means that a difference between a position of the top dead center and the position of the suction port 41 in the circumferential direction is reduced as the opening center of the suction port 41 is brought close to the line connecting the top dead center of the cam surface 61 and the rotation center axis C1, and "the phase difference between the bottom dead center and the discharge port 45 in the circumferential direction is reduced" means that a difference between a position of the bottom dead center and the position of the discharge port 45 in the circumferential direction is reduced as the opening center of the discharge port 45 is brought close to the line connecting the bottom dead center of the cam surface 61 and the rotation center axis C1.
Therefore, the amount of the working fluid guided into each capacity chamber 32 can be easily increased or reduced by causing the port block 50 to rotate about the rotation center axis C1 by the capacity changing unit 70, and appropriately changing a magnitude of the phase difference between the top dead center and the suction port 41 and a magnitude of the phase difference between the bottom dead center and the discharge port 45, that is, appropriately changing the ratio of the first period T1 in which the suction-enabled period and the contraction period overlap with each other and the second period T2 in which the suction-enabled period and the expansion period overlap with each other.
As described above, according to the pump 100 having the above-described configuration including the capacity changing unit 70, the discharge amount of the pump 100 can be adjusted to a desired amount by appropriately changing a position of the port block 50 between a maximum position at which the discharge amount is maximum and a minimum position at which the discharge amount is minimum, and for example, the discharge amount of the pump 100 can be set to about 50% of a maximum discharge amount by expressing an angle difference (for example, 15°) between the maximum position and the minimum position in percentage and adjusting the position of the port block 50 to a position corresponding to 50% by the capacity changing unit 70.
According to the above embodiment, the following effects are achieved.
In the pump 100 having the above-described configuration, the amount of the working fluid guided into each capacity chamber 32, that is, the discharge amount of the pump 100 is changed by causing the port block 50 to rotate about the rotation center axis C1 and changing the relative positional relation between the port block 50 and the cam ring 60.
Accordingly, in order to change the discharge amount of the pump 100, it is only necessary to cause the port block 50 to rotate about the rotation center axis C1, and there is no need to cause any member to move along the direction of the rotation center axis C1 or along the radial direction, and thus there is no need to ensure a space for allowing movement of the member in the axial direction and the radial direction. Therefore, the pump 100 of a variable capacity type can be made compact.
The following modifications are also within the scope of the present invention, and it is also possible to combine configurations shown in the modifications with the configurations described in the above-described embodiment, or to combine the configurations described in the following different modifications.
In the above-described embodiment, the relative positional relation between the port block 50 and the cam ring 60 is changed by causing the port block 50 to rotate about the rotation center axis C1. Alternatively, the relative positional relation between the port block 50 and the cam ring 60 may be changed by causing the cam ring 60 to rotate about the rotation center axis C1 as in a modification illustrated in FIG. 15.
In a pump 200 illustrated in FIG. 15, a capacity changing unit 170 includes a control pin 171 having one end rotatably inserted into a hole formed in a side surface of the cam ring 60, and a load applying unit (not illustrated) configured to apply a load for causing the cam ring 60 to rotate about the rotation center axis C1 to the cam ring 60 via the control pin 171, and the capacity changing unit 170 causes the cam ring 60 to rotate by causing a pressing force of a control piston (not illustrated) functioning as the load applying unit or a biasing force of a control spring (not illustrated) to act on the control pin 171. As described above, also in a case where the cam ring 60 is caused to rotate, the relative positional relation between the suction port 41 and the discharge port 45 with respect to the top dead center and the bottom dead center of the cam surface 61 is changed, and thus the amount of the working fluid guided into each capacity chamber 32, that is, a discharge amount of the pump 200 can be changed by the same mechanism as in the above-described embodiment.
In order to change the discharge amount of the pump 200 in the modification, it is only necessary to cause the cam ring 60 to rotate about the rotation center axis C1, and there is no need to cause any member to move along the direction of the rotation center axis C1 or along the radial direction, and thus there is no need to ensure a space for allowing movement of the member in the axial direction and the radial direction. Therefore, similarly to the above-described embodiment, the pump 200 of a variable capacity type can be made compact.
As illustrated in FIG. 15, the capacity changing unit 170 in the modification is disposed on a side opposite to the sliding contact surfaces 34 and 55 between the cylinder block 30 and the port block 50 across the cam ring 60 in the axial direction of the rotation center axis C1. Therefore, even in a case where the capacity changing unit 170 is provided to make the pump 200 of a variable capacity type, an increase in size of the pump 200 in the radial direction can be suppressed.
In the above-described embodiment, the suction port 41 is brought close to a top dead center side from the intermediate position between the top dead center and the bottom dead center of the cam surface 61, and the discharge port 45 is brought close to a bottom dead center side from the intermediate position between the bottom dead center and the top dead center of the cam surface 61, thereby reducing the amount of the working fluid guided into each capacity chamber 32. Alternatively, the amount of the working fluid guided into each capacity chamber 32 may be reduced by bringing the suction port 41 close to the bottom dead center side rather than the top dead center side from the intermediate position and bringing the discharge port 45 close to the top dead center side rather than the bottom dead center side from the intermediate position.
Also in a case where the relative positional relation between the port block 50 and the cam ring 60 is set such that the suction port 41 opens at the same position as the bottom dead center of the cam surface 61 in the circumferential direction and the discharge port 45 opens at the same position as the top dead center of the cam surface 61 in the circumferential direction, the amount of the working fluid sucked into the capacity chamber 32 through the suction port 41 in the suction process is substantially zero, and the amount of the working fluid discharged from the capacity chamber 32 through the discharge port 45 in the discharge process is also substantially zero. As a result, the discharge amount of the pump 100 is substantially zero, that is, minimum.
That is, the amount of the working fluid discharged from each capacity chamber 32 is reduced as the phase difference between the bottom dead center and the suction port 41 in the circumferential direction is reduced and as the phase difference between the top dead center and the discharge port 45 in the circumferential direction is reduced, that is, as the period in which the suction-enabled period and the contraction period overlap with each other is increased.
Accordingly, also in a case where the port block 50 is caused to rotate in a direction opposite to the arrow M in FIG. 9 around the rotation center axis C1 by the capacity changing unit 70, and the magnitude of the phase difference between the bottom dead center and the suction port 41 and the magnitude of the phase difference between the top dead center and the discharge port 45 are appropriately changed, the amount of the working fluid guided into each capacity chamber 32 can be easily increased or reduced as in the above-described embodiment.
In the above-described embodiment, a case where the radial piston pump motor 100 functions as a pump is described, but the radial piston pump motor 100 may function as a motor, and in this case, the first port 41 serves as a supply port for supplying a pressurized working fluid to the capacity chamber 32, and the second port 45 serves as a discharge port for discharging the working fluid from the capacity chamber 32 to the tank. An output in the case where the radial piston pump motor 100 functions as a motor can be adjusted by changing the relative positional relation between the port block 50 and the cam ring 60, as in the above-described embodiment. In the case where the radial piston pump motor 100 functions as a motor, a period in which the communication hole 33 and the supply port (first port 41) communicate with each other and the pressurized working fluid can be supplied into the capacity chamber 32 corresponds to the suction-enabled period in the above-described embodiment, that is, the supply-enabled period in which the working fluid can be supplied into the capacity chamber 32.
In the above-described embodiment, a cross-sectional shape of the communication hole 33, the suction port 41, and the discharge port 45 is a circular shape, but the cross-sectional shape thereof is not limited to the circular shape, and may be, for example, an elliptical shape or a rectangular shape. In addition, the communication hole 33 opens at the center of the capacity chamber 32 in the above-described embodiment, but the communication hole 33 may open at a position deviated from the center of the capacity chamber 32. As described above, even in the case where the communication hole 33 does not open at the center of the capacity chamber 32, the amount of the working fluid guided into each capacity chamber 32 can be increased or reduced by changing the ratio of the first period T1 in which the contraction period and the suction-enabled period overlap with each other and the second period T2 in which the expansion period and the suction-enabled period overlap with each other as described above.
The configurations, functions, and effects of the embodiments of the present invention configured as described above will be collectively described.
The radial piston pump motors 100 and 200 include the housing 10; the cylinder block 30 accommodated in the housing 10 and rotating together with the shaft 20; the plurality of cylinders 31 formed radially in the cylinder block 30 about the rotation center axis C1 of the shaft 20; the plurality of pistons 36 slidably inserted into the cylinder 31 and defining the capacity chambers 32 in the cylinder 31, respectively; and the suction port 41 (first port) through which the working fluid supplied to the capacity chambers 32 flows and the discharge port 45 (second port) through which the working fluid discharged from the capacity chambers 32 flows, and the radial piston pump motors 100 and 200 are provided with the port block 50 disposed in the housing 10 so as to be in sliding contact with the cylinder block 30; the cam ring 60 having the cam surface 61 with which the tip of the piston 36 comes into contact as the cylinder block 30 rotates; and the capacity changing unit 70 and 170 configured to change the amount of the working fluid guided into the capacity chamber 32 by causing at least one of the port block 50 and the cam ring 60 to rotate about the rotation center axis C1 and changing the relative positional relation between the port block 50 and the cam ring 60.
According to this configuration, the amount of the working fluid guided into each capacity chamber 32 is changed by causing at least one of the port block 50 and the cam ring 60 to rotate about the rotation center axis C1 and changing the relative positional relation between the port block 50 and the cam ring 60.
Accordingly, in order to change the amount of the working fluid guided into each capacity chamber 32, it is only necessary to cause at least one of the port block 50 and the cam ring 60 to rotate about the rotation center axis C1, and there is no need to cause any member to move along the direction of the rotation center axis C1 or along the radial direction, and thus there is no need to ensure a space for allowing movement of the member in the axial direction and the radial direction. Therefore, the variable capacity type radial piston pump motors 100 and 200 can be made compact.
The capacity changing units 70 and 170 are mechanisms configured to cause any one of the port block 50 and the cam ring 60 to rotate about the rotation center axis C1, and are disposed on the side opposite to the sliding contact surfaces 34 and 55 between the cylinder block 30 and the port block 50 across any one of the port block 50 and the cam ring 60 in the axial direction of the rotation center axis C1.
In this configuration, the capacity changing unit 70 configured to cause the port block 50 to rotate about the rotation center axis C1 is disposed not on the outer side in the radial direction of the port block 50 or the outer side in the radial direction of the cam ring 60, but on the side opposite to the sliding contact surfaces 34 and 55 between the cylinder block 30 and the port block 50 across the port block 50 in the axial direction of the rotation center axis C1. In this configuration, the capacity changing unit 170 configured to cause the cam ring 60 to rotate about the rotation center axis C1 is disposed not on the outer side in the radial direction of the cam ring 60, but on the side opposite to the sliding contact surfaces 34 and 55 between the cylinder block 30 and the port block 50 across the cam ring 60 in the axial direction of the rotation center axis C1. Therefore, an increase in size of the variable capacity type radial piston pump motors 100 and 200 on the outer side in the radial direction can be suppressed.
The capacity changing units 70 and 170 include the control pins 71 and 171 having one end inserted into the port block 50 or the cam ring 60, and a load applying unit configured to apply, to the port block 50 or the cam ring 60 via the control pins 71 and 171, a load for causing the port block 50 or the cam ring 60 into which the control pins 71 and 171 are inserted to rotate about the rotation center axis C1.
In this configuration, the load for causing the port block 50 or the cam ring 60 to rotate about the rotation center axis C1 is applied via the control pins 71 and 171. Therefore, by changing the load applied to the control pins 71 and 171, the rotation amount of the port block 50 or the cam ring 60, that is, the relative positional relation between the port block 50 and the cam ring 60 can be easily changed, and as a result, the amount of the working fluid guided into each capacity chamber 32 can be easily changed.
The cylinder block 30 has the communication hole 33 capable of causing the cylinder 31 to communicate with the suction port 41 (first port) and the discharge port 45 (second port), and the amount of the working fluid guided into the capacity chamber 32 is changed by changing the ratio between the first period T1 and the second period T2 by the capacity changing units 70 and 170, the first period T1 being a period in which the supply-enabled period in which the communication hole 33 and the suction port 41 (first port) communicate with each other and the contraction period in which the capacity of the capacity chamber 32 contracts, and the second period T2 being a period in which the supply-enabled period and the expansion period in which the capacity of the capacity chamber 32 expands overlap with each other.
In this configuration, the amount of the working fluid guided into each capacity chamber 32 can be easily increased or reduced by causing at least one of the port block 50 and the cam ring 60 to rotate about the rotation center axis C1 by the capacity changing units 70 and 170 and appropriately changing the ratio of the first period T1 and the second period T2, the first period T1 being a period in which the suction-enabled period and the contraction period overlap with each other, and the second period T2 being a period in which the suction-enabled period and the expansion period overlap with each other.
The piston 36 has the spherical body 38 that comes into contact with the cam surface 61 while rotating with the rotation of the cylinder block 30, and the arc-shaped groove formed in accordance with the curvature of the spherical body 38 is provided along the circumferential direction on the surface of the cam surface 61.
In this configuration, the arc-shaped groove formed in accordance with the curvature of the spherical body 38 provided in the piston 36 is provided along the circumferential direction on the surface of the cam surface 61. Therefore, the spherical body 38 provided on the piston 36 smoothly moves while rolling on the cam surface 61 without coming off the cam surface 61. Accordingly, the piston 36 can be caused to smoothly reciprocate in the cylinder 31 according to the profile of the cam surface 61.
Embodiments of the present invention were described above, but the above embodiments are merely examples of applications of the present invention, and the technical scope of the present invention is not limited to the specific constitutions of the above embodiments.
This application claims priority based on Japanese Patent Application No. 2023-74501 filed with the Japan Patent Office on April 28, 2023 , the entire contents of which are incorporated into this specification by reference.

Claims

A variable capacity type hydraulic rotating machine, comprising:
a housing;

a cylinder block accommodated in the housing and configured to rotate together with a shaft;

a plurality of cylinders formed radially in the cylinder block about a rotation center axis of the shaft;

a plurality of pistons slidably inserted into the cylinders and defining respective capacity chambers inside the cylinders;

a port block having a first port through which a working fluid supplied to the capacity chamber flows and a second port through which a working fluid discharged from the capacity chamber flows, and disposed in the housing so as to be in sliding contact with the cylinder block;

a cam ring having a cam surface with which a tip of the piston comes into contact as the cylinder block rotates; and

a capacity changing unit configured to change an amount of the working fluid guided into the capacity chamber by causing at least one of the port block and the cam ring to rotate about the rotation center axis and changing a relative positional relation between the port block and the cam ring.
The hydraulic rotating machine according to claim 1, wherein
the capacity changing unit is a mechanism configured to cause any one of the port block and the cam ring to rotate about the rotation center axis, and is disposed on a side opposite to a sliding contact surface between the cylinder block and the port block across any one of the port block and the cam ring in an axial direction of the rotation center axis.
The hydraulic rotating machine according to claim 1, wherein
the capacity changing unit includes

a control pin having one end inserted into the port block or the cam ring, and

a load applying unit configured to apply, to the port block or the cam ring via the control pin, a load for causing the port block or the cam ring into which the control pin is inserted to rotate about the rotation center axis.
The hydraulic rotating machine according to claim 1, wherein
the cylinder block has a communication hole capable of allowing the cylinder to communicate with the first port and the second port, and

the amount of the working fluid guided into the capacity chamber is changed by changing a ratio between a first period and a second period by the capacity changing unit, the first period being a period in which a supply-enabled period in which the communication hole and the first port communicate with each other and a contraction period in which a capacity of the capacity chamber contracts overlap with each other, and the second period being a period in which the supply-enabled period and an expansion period in which the capacity of the capacity chamber expands overlap with each other.
The hydraulic rotating machine according to claim 1, wherein
the piston has a spherical body that comes into contact with the cam surface while rotating with the rotation of the cylinder block, and

an arc-shaped groove formed in accordance with a curvature of the spherical body is provided along a circumferential direction on a surface of the cam surface.