JP2018100621A - Axial piston pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial piston pump capable of stably controlling an inclination angle of a swash plate.SOLUTION: An axial piston pump 100 includes: a swash plate 40 that has a cam part 43 moving integrally with the swash plate 40 between a first position P1 where an inclination angle of a support surface 41 becomes a first angle α1, and a second position P2 where the inclination angle of the support surface 41 becomes a second angle α2; and a controller 50 that has a control side piston 52 arranged on a virtual straight line L passing through the first position P1 and the second position P2 and capable of moving in a direction parallel with the virtual straight line L in a state of being brought into a linear or point contact with the cam part 43, and a control side cylinder 51 configured to store the control side piston 52 in a movable manner.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an axial piston pump.

  A swash plate type axial piston pump includes a cylinder barrel rotatably provided inside a casing, a plurality of pump side cylinders formed in the cylinder barrel, and a pump side piston provided in each of the pump side cylinders, It has a swash plate which slidably supports each pump side piston (for example, refer patent document 1).

  In this axial piston pump, when the cylinder barrel rotates, the pump-side piston slides along the swash plate and reciprocates inside the cylinder. When the pump side piston moves from the bottom dead center to the top dead center, the cylinder is connected to the suction port via the cylinder port and sucks the working fluid from the suction port. On the other hand, when the pump-side piston moves from the top dead center to the bottom dead center, the cylinder is connected to the discharge port via the cylinder port, and discharges the working fluid to the discharge port.

JP 2009-197709 A

  In the above axial piston pump, the inclination angle of the swash plate can be adjusted by a controller disposed outside the casing. By adjusting the inclination angle of the swash plate, the stroke of the pump side piston is adjusted, and the flow rate of the working fluid is adjusted. The controller includes, for example, a control cylinder and a control piston inside. The control side piston is provided so as to be capable of reciprocating in the control side cylinder. A link member that moves integrally with the control side piston is connected to the control side piston. The link member extends from the control side piston to the casing side and is connected to the swash plate side via a connecting pin. In this configuration, when the control-side piston is reciprocated, the connection pin moves through the link member, and the inclination angle of the swash plate changes due to the movement of the connection pin.

  In the above axial piston pump, a load is applied to the swash plate by the pressure of the working fluid from the pump side piston to the swash plate by rotating the cylinder barrel. This load also acts on the link member and the control side piston via the connecting pin. In the above configuration, since the control-side piston and the connection pin are disposed at positions separated by the length of the link member, the pressure acting on the connection pin acts as a moment on the control-side piston. The control-side piston is in a state of pressing the inner wall of the control-side cylinder by this moment. If the control-side piston is reciprocated in this state, there is a possibility that a gap is generated between the control-side piston and the inner wall of the control-side cylinder. In this case, the working fluid that operates the control-side piston leaks from the gap, and the stability when controlling the tilt angle of the swash plate may be reduced.

  The present invention has been made in view of the above, and an object thereof is to provide an axial piston pump capable of stably controlling the inclination angle of a swash plate.

  An axial piston pump according to the present invention is disposed inside a casing and is rotatable around a rotation axis, and is disposed at a predetermined interval around the axis of the rotation shaft on the cylinder barrel. A plurality of pump-side cylinders parallel to the axial direction and a pump-side piston that is provided in each of the plurality of pump-side cylinders and can reciprocate in the axial direction, and the end of each pump-side piston can slide. The support surface is supported on the axis, and the tilt angle of the support surface with respect to the plane perpendicular to the axial direction is changed from the first angle to the second angle by rotating in the direction around the axis of the central axis orthogonal to the rotation axis. And a controller for controlling the inclination angle of the support surface. The swash plate has a first position where the inclination angle of the support surface is the first angle and the support. A cam portion that moves integrally with the swash plate between a second position at which the inclination angle of the surface is the second angle, and the controller is a virtual that passes through the first position and the second position. A control-side piston that is arranged on a straight line and is movable in a direction parallel to the virtual straight line in contact with the cam portion at a line or point; and a control-side cylinder that movably accommodates the control-side piston. Have.

  According to the present invention, since the swash plate is brought into contact with the control side piston via the cam portion, the load from the working fluid applied to the swash plate from the pump side piston is applied to the control side piston from the cam portion. It acts linearly in the direction of the virtual straight line. In addition, since the control-side piston is arranged on the virtual straight line and can move in a direction parallel to the virtual straight line, the contact position between the cam portion and the control-side piston is prevented from moving away from the central axis of the control-side piston. The For this reason, it can suppress that a moment acts with respect to a control side piston. Thereby, since wear between the control side piston and the control side cylinder is suppressed, leakage of the working fluid is suppressed, and the inclination angle of the swash plate can be controlled stably.

  The cam portion may be arranged in a state where the virtual straight line is inclined with respect to the rotation axis.

  According to the present invention, the control-side piston moves in a direction inclined with respect to the rotation axis by arranging the cam portion in a state where the virtual straight line is inclined with respect to the rotation axis. Thereby, since it becomes possible to arrange | position a control side piston close to the casing side, size reduction of the whole pump can be achieved.

  The cam portion may have a curved surface at a contact portion with the control-side piston.

  According to the present invention, when the control-side piston moves, the cam portion can come into contact with the control-side piston while being moved so as to slide on the control-side piston.

  The cam portion may have a roller at a contact portion with the control-side piston.

  According to the present invention, when the control-side piston moves, the roller portion of the cam portion can be abutted while rolling on the control-side piston.

  ADVANTAGE OF THE INVENTION According to this invention, the axial piston pump which can control the inclination angle of a swash plate stably can be provided.

FIG. 1 is a cross-sectional view showing an example of an axial piston pump according to the present embodiment. FIG. 2 is a diagram illustrating an example when the inclination angle of the support surface is changed. FIG. 3 is a diagram illustrating an example when the inclination angle of the support surface is changed. FIG. 4 is a diagram schematically illustrating a positional relationship between the control side cylinder and the control side piston and the cam portion. FIG. 5 is a cross-sectional view showing a control-side piston according to a modification. FIG. 6 is a plan view showing a control-side piston according to a modification. FIG. 7 is a perspective view showing a cam portion according to a modification. FIG. 8 is a cross-sectional view of the cam portion including a virtual straight line. FIG. 9 is a diagram illustrating an example of a cam portion according to a modification.

  Hereinafter, an embodiment of an axial piston pump according to the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a cross-sectional view showing an example of an axial piston pump 100 according to the present embodiment. As shown in FIG. 1, an axial piston pump 100 according to this embodiment is a swash plate type variable displacement hydraulic pump, and oil is used as a working fluid. The axial piston pump 100 includes a cylinder barrel 10, a pump side cylinder 20, a pump side piston 30, a swash plate 40, and a controller 50.

  The cylinder barrel 10 is disposed inside the casing 2 and is fixed to the shaft member 3 by, for example, a key or a spline. The shaft member 3 is supported so as to be rotatable around the axis of the rotation axis AX with respect to the casing 2. Therefore, the cylinder barrel 10 is integrated with the shaft member 3 and supported so as to be rotatable around the axis of the rotation axis AX.

  A plurality of pump-side cylinders 20 are provided in the cylinder barrel 10. The plurality of pump-side cylinders 20 are arranged at predetermined intervals in the direction around the rotation axis AX. The pump side cylinder 20 has an inner wall formed in a cylindrical shape, for example, and is arranged in parallel to the axial direction of the rotation axis AX. A cylinder port 21 is provided on the end surface of the pump side cylinder 20. The cylinder port 21 is connected to the suction port 4 or the discharge port 5. The discharge port 5 is connected to the servo valve 6 via a pipe 7.

  The pump side piston 30 is provided in each of the pump side cylinders 20. The pump-side piston 30 can reciprocate in the axial direction of the rotation axis AX while in contact with the inner wall of the pump-side cylinder 20. A head (end) 31 of the pump-side piston 30 protrudes from the inside of the pump-side cylinder 20 toward the swash plate 40. The head 31 is supported by the swash plate 40.

  The swash plate 40 includes a support surface 41, a curved surface 42, and a cam portion 43. The support surface 41 slidably supports the head portion 31 of the pump-side piston 30. The curved surface 42 is disposed on the opposite side of the support surface 41 in the axial direction of the rotation axis AX. The curved surface 42 is a part of a cylindrical surface, for example. The curved surface 42 is disposed so that the central axis BX is orthogonal to the rotation axis AX. The curved surface 42 is slidably supported by the bearing member 44. The bearing member 44 is fixed inside the casing 2, and the inner peripheral side is formed in a cylindrical shape corresponding to the curved surface 42. The bearing member 44 is formed using a metal such as copper, for example.

  The swash plate 40 is provided so as not to rotate in the direction around the rotation axis AX. With this configuration, when the cylinder barrel 10 rotates in the direction around the rotation axis AX, the swash plate 40 causes the head 31 of the pump side piston 30 to slide in the direction around the axis of the rotation axis AX. Can be reciprocated in the axial direction of the rotation axis AX.

  Further, the swash plate 40 is provided so as to be rotatable around the central axis BX. The inclination angle of the support surface 41 is changed by rotating the swash plate 40 about the central axis BX. When the swash plate 40 rotates in the direction around the central axis BX, the curved surface 42 rotates along the bearing member 44 and maintains the state supported by the bearing member 44. Thereby, the swash plate 40 can adjust the inclination angle of the support surface 41 to a desired angle.

  2 and 3 are diagrams illustrating an example when the inclination angle of the support surface 41 is changed. As shown in FIGS. 2 and 3, in the swash plate 40, the inclination angle of the support surface 41 with respect to the surface S perpendicular to the axial direction of the rotation axis AX is variable in the range from the first angle α1 to the second angle α2. . By adjusting the inclination angle of the support surface 41, the stroke of the reciprocating movement of the pump-side piston 30 can be adjusted.

  The cam portion 43 of the swash plate 40 moves integrally with the swash plate 40. The cam portion 43 moves integrally with the swash plate 40 between the first position P1 and the second position P2. The first position P1 is a position when the inclination angle of the support surface 41 becomes the first angle α1. The second position P2 is a position when the inclination angle of the curved surface 42 becomes the second angle α2. The cam portion 43 has a spherical portion 45 at the tip. The spherical portion 45 is formed in a spherical shape. In the present embodiment, the first position P <b> 1 and the second position P <b> 2 are the center positions of the spherical portion 45.

  The controller 50 controls the inclination angle of the support surface 41 of the swash plate 40. The controller 50 includes a control side cylinder 51, a control side piston 52, and a stroke adjustment member 53. The control side cylinder 51 includes a first cylinder 51a and a second cylinder 51b. The first cylinder 51a has a larger inner diameter than the second cylinder 51b. In the present embodiment, the control side cylinder 51 is provided as a part of the casing 2, but is not limited thereto. For example, the control side cylinder 51 may be configured to be attached to the outside of the casing 2.

  The control side piston 52 has a first piston 52a and a second piston 52b. The first piston 52a has a diameter corresponding to the inner diameter of the first cylinder 51a. The first piston 52a reciprocates inside the first cylinder 51a. The second piston 52b has a diameter corresponding to the inner diameter of the second cylinder 51b. The second piston 52b reciprocates inside the second cylinder 51b.

  The stroke adjustment member 53 includes a first adjustment member 53a and a second adjustment member 53b. The first adjustment member 53a is inserted into the end portion of the first cylinder 51a. The first adjustment member 53a adjusts the stroke of the first piston 52a. The second adjustment member 53b is inserted into the end of the second cylinder 51b. The second adjustment member 53b adjusts the stroke of the second piston 52b.

  A space K1 is formed between the end of the first cylinder 51a and the first piston 52a. The space K1 is connected to the servo valve 6 via the pipe 9. Part of the working fluid discharged from the discharge port 5 is supplied to the space K <b> 1 by switching the servo valve 6. A space K2 is formed between the end of the first cylinder 51a and the second piston 52b. The space K2 is connected to the pipe 7 via the pipe 8. Part of the working fluid discharged from the discharge port 5 is supplied to the space K2. The positions of the first piston 52a and the second piston 52b can be adjusted by supplying the working fluid to the space K1 and the space K2 and adjusting the internal pressure.

  FIG. 4 is a diagram schematically illustrating a positional relationship between the control side cylinder 51 and the control side piston 52 and the cam portion 43. As shown in FIG. 4, the first piston 52 a and the second piston 52 b are disposed on the virtual straight line L. The virtual straight line L is a straight line passing through the first position P1 and the second position P2, which are both ends of the movable range of the cam portion 43. For example, the first piston 52a and the second piston 52b are arranged so that the central axes thereof coincide with the virtual straight line L, but are not limited thereto. The first piston 52a and the second piston 52b move in a direction parallel to the virtual straight line L. The first piston 52 a and the second piston 52 b are disposed at positions that sandwich the cam portion 43. The first piston 52a and the second piston 52b are in contact with the spherical surface portion 45 of the cam portion 43 at points. By adjusting the pressures in the space K1 and the space K2, the first piston 52a and the second piston 52b can move in a direction parallel to the imaginary straight line L while being in contact with the cam portion 43, respectively.

  The cam portion 43 moves between the first position P1 and the second position P2 as the first piston 52a and the second piston 52b move. By the movement of the cam portion 43, the swash plate 40 rotates around the center axis BX. The cam portion 43 is provided integrally with the swash plate 40. Therefore, the trajectory Q of the cam portion 43 is part of an arc that passes through the first position P1 and the second position P2 with the central axis BX as the center.

  In the axial piston pump 100 described above, for example, when the shaft member 3 is rotated by an external motor or the like, the cylinder barrel 10 rotates as the shaft member 3 rotates. When the cylinder barrel 10 rotates, the head portion 31 of the pump-side piston 30 slides in the direction around the rotation axis AX. Accordingly, the pump-side piston 30 reciprocates in the pump-side cylinder 20 in the axial direction of the rotation axis AX.

  While the pump side piston 30 moves from the bottom dead center to the top dead center, the pump side cylinder 20 is connected to the suction port 4 via the cylinder port 21. In this case, the working fluid is sucked into the pump side cylinder 20 as the pump side piston 30 moves. Further, while the pump side piston 30 moves from the top dead center to the bottom dead center, the pump side cylinder 20 is connected to the discharge port 5 via the cylinder port 21. In this case, the working fluid is discharged from the pump side cylinder 20 to the discharge port 5 as the pump side piston 30 moves.

  The working fluid discharged from the discharge port 5 is supplied to an external actuator or the like via the pipe 7. A part of the working fluid supplied to the pipe 7 is supplied to the space K2 of the second cylinder 51b through the pipe 8. In this case, the second piston 52b presses the cam portion 43 toward the first cylinder 51a. Due to the pressing force of the second piston 52b, the first piston 52a causes the first adjustment member 53a to sandwich the spherical portion 45 of the cam portion 43 with the second piston 52b in a direction parallel to the virtual straight line L. Abut. Therefore, the inclination angle of the support surface 41 of the swash plate 40 is maintained at the inclination angle α1 having the largest inclination with respect to the plane S perpendicular to the rotation axis AX.

  When the inclination angle of the support surface 41 is made smaller than α1, the working fluid is supplied to the space K1 of the first cylinder 51a by switching the servo valve 6. In this case, the first piston 52a presses the cam portion 43 toward the second cylinder 51b. The cam portion 43 moves to the second piston 52b side by the pressing force of the first piston 52a. By the movement of the cam portion 43, the swash plate 40 rotates about the central axis BX, and the inclination angle of the support surface 41 is adjusted.

  In such an axial piston pump 100, the load by the working fluid is applied from the pump side piston 30 to the swash plate 40 by rotating the cylinder barrel 10. This pressure also acts on the control side piston 52 (first piston 52a, second piston 52b) via the cam portion 43.

  In contrast, the axial piston pump 100 according to the present embodiment is applied to the swash plate 40 from the pump side piston 30 because the swash plate 40 is brought into contact with the control side piston 52 via the cam portion 43. The pressure from the working fluid acts linearly in the direction of the imaginary straight line L from the cam portion 43 to the control side piston 52. Further, since the control side piston 52 is arranged on the virtual straight line L and can move in a direction parallel to the virtual straight line L, the contact position between the cam portion 43 and the control side piston 52 is the central axis of the control side piston 52. It is restrained from leaving. For this reason, it is possible to suppress the moment from acting on the control-side piston 52. Thereby, since wear between the control side piston 52 and the control side cylinder 51 is suppressed, leakage of the working fluid is suppressed and the inclination angle of the swash plate 40 can be controlled stably.

  Further, in the axial piston pump 100 according to the present embodiment, the cam portion 43 is arranged in a state where the virtual straight line L is inclined with respect to the rotation axis AX. In this configuration, the control side piston 52 moves in a direction inclined with respect to the rotation axis AX. Thereby, since it becomes possible to arrange | position the control side piston 52 close to the casing 2 side, size reduction of the whole pump can be achieved.

  Further, in the axial piston pump 100 according to the present embodiment, the cam portion 43 has a curved contact portion with the control side piston 52. With this configuration, when the control-side piston 52 moves, the cam portion 43 can be brought into contact with the control-side piston 52 so as to slide on the control-side piston 52, and the relative slip between the cam portion 43 and the control-side piston 52 can be achieved. The amount is minimized. Thereby, abrasion of the contact part of the cam part 43 and the control side piston 52 can be suppressed.

  The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the configuration in which the cam portion 43 is in contact with the control-side piston 52 in the spherical portion 45 has been described as an example, but the configuration is not limited thereto.

  FIG. 5 is a cross-sectional view showing a control-side piston 62 according to a modification. FIG. 6 is a plan view showing an example of the cam portion 43 and the control side piston 62. FIG. 5 shows a cross section of the cam portion 43 and the control side piston 62 including the virtual straight line L in FIG.

  The control-side piston 62 shown in FIGS. 5 and 6 includes a first piston 52a and a second piston 52b that are integrated with each other. The first piston 52 a has a cylindrical sleeve member 65. The sleeve member 65 is formed through the first piston 52a. An inner peripheral surface 65 a of the sleeve member 65 has a cylindrical surface shape and has an inner diameter substantially equal to the diameter of the cam portion 43.

  The cam portion 43 is inserted into the sleeve member 65. The cam portion 43 contacts the inner peripheral surface 65a. Thus, since the cam part 43 is contact | abutted to the internal peripheral surface 65a which is a cylindrical surface, the contact surface pressure between the cam part 43 and the sleeve member 65 is suppressed. 5 and 6, the sleeve member 65 is provided on the first piston 52a. However, the present invention is not limited to this, and the sleeve member 65 may be provided on the second piston 52b.

  FIG. 7 is a perspective view showing a cam portion 43B according to a modification. FIG. 8 is a cross-sectional view of the cam portion 43B including the virtual straight line L.

  The cam portion 43 </ b> B illustrated in FIGS. 7 and 8 has a configuration including a bearing portion 71, a shaft member 72, and a roller member 73. The bearing portion 71 is fixed to the swash plate 40 and supports the shaft member 72 in a rotatable manner. The shaft member 72 is formed in a columnar shape, for example. The roller member 73 is provided integrally with the shaft member 72. The roller member 73 is formed in a cylindrical shape having a central axis common to the shaft member 72, for example.

  The roller member 73 has a cylindrical surface 73a. The cylindrical surface 73a has one end of the virtual straight line L in contact with the first piston 52a with a line and the other end in contact with the second piston 52b with a line. With this configuration, the contact range is larger in the point of contact with the control-side piston 52 than in the configuration of contact with the control-side piston 52, so that concentration of pressure on the control-side piston 52 can be reduced. Thereby, abrasion between the cam part 43B and the control side piston 52 can be reduced.

  Moreover, in the said embodiment, although demonstrated taking the example of the structure by which the cam part 43 was arrange | positioned so that the virtual straight line L might incline with respect to the rotating shaft AX, it is not limited to this. FIG. 9 is a diagram illustrating an example of the cam portion 43C according to the modification. The cam portion 43C shown in FIG. 9 moves integrally with the swash plate 40 on the track QC between the third position P3 and the fourth position P4. The third position P3 is a position when the inclination angle of the support surface 41 becomes the first angle α1. The fourth position P4 is a position when the inclination angle of the support surface 41 becomes the second angle α2. In this configuration, the virtual straight line LC passing through the third position P3 and the fourth position P4 is parallel to the rotation axis AX.

  Further, the control side cylinder 51 (first cylinder 51a, second cylinder 51b) and the control side piston 52 (first piston 52a, second piston 52b) are arranged in parallel to the virtual straight line LC. Further, the first piston 52a and the second piston 52b move in parallel to the virtual straight line LC. Accordingly, it is possible to suppress wear between the control side piston 52 and the control side cylinder 51 while adopting a configuration in which the control side cylinder 51 and the control side piston 52 are parallel to the rotation axis AX. For this reason, the burden of the design change with respect to the structure of the conventional controller can be reduced.

  In the above embodiment, the configuration in which the control-side piston 52 is separated into the first piston 52a and the second piston 52b has been described as an example, but the present invention is not limited to this. The control side piston 52 may be configured such that the first piston 52a and the second piston 52b are integrally formed.

2 Casing 3, 62, 72 Shaft member 4 Suction port 5 Discharge port 6 Servo valve 7, 8, 9 Piping 10 Cylinder barrel 20 Pump side cylinder 21 Cylinder port 30 Pump side piston 31 Head 40 Swash plate 41 Support surface 42 Curved surface 43, 43A, 43B, 43C Cam portion 44 Bearing member 45 Spherical surface portion 50 Controller 51 Control side cylinder 51a First cylinder 51b Second cylinder 52 Control side piston 52a First piston 52b Second piston 53 Stroke adjustment member 53a First adjustment Member 53b Second adjusting member 61, 71 Bearing part 63 Rod-like member 63a, 63b Hemispherical part 73 Roller member 73a Cylindrical surface 100 Axial piston pump α1 First angle α2 Second angle K1, K2 Space L, LC Virtual straight line P1 First position P2 2nd position S surface P3 3rd position P4 4th position AX Rotation axis BX Center axis

Claims (4)

A cylinder barrel arranged inside the casing and rotatable about a rotation axis;
A plurality of pump-side cylinders arranged at predetermined intervals in a direction around the axis of the rotary shaft in the cylinder barrel, and parallel to the axial direction of the rotary shaft;
A pump-side piston provided in each of the plurality of pump-side cylinders and capable of reciprocating in the axial direction;
A support surface for slidably supporting the end of each pump-side piston, and the support for a surface perpendicular to the axial direction by rotating around a central axis perpendicular to the rotation axis; A swash plate whose surface inclination angle is variable in a range from a first angle to a second angle;
A controller for controlling an inclination angle of the support surface,
The swash plate moves integrally with the swash plate between a first position where the inclination angle of the support surface becomes the first angle and a second position where the inclination angle of the support surface becomes the second angle. Having a cam part,
The controller is disposed on an imaginary straight line passing through the first position and the second position, and can be moved in a direction parallel to the imaginary straight line while being in contact with the cam portion at a line or a point. An axial piston pump comprising: a control side cylinder that movably accommodates the control side piston.   The axial piston pump according to claim 1, wherein the cam portion is disposed in a state where the virtual straight line is inclined with respect to the rotation axis.   The axial piston pump according to claim 1, wherein the cam portion has a curved surface at a contact portion with the control-side piston.   The axial piston pump according to any one of claims 1 to 3, wherein the cam portion includes a roller at a contact portion with the control-side piston.

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