JP6147021B2 - Fluid pressure pump - Google Patents

Description

The present invention relates to axial piston type variable displacement pump.

  A conventional axial piston type pump includes a cylinder block that holds the pump piston so that the pump piston can advance and retract, a pump piston that supplies and discharges working fluid, and a swash plate that advances and retracts the pump piston as the cylinder block rotates. . The axial piston type variable displacement pump can change the discharge flow rate of the working fluid by adjusting the angle of the swash plate (hereinafter referred to as swash plate angle θ).

  An axial piston type pump capable of rotating in both directions is also used for control of a control surface in some aircraft. In such applications, in order to reduce the power consumption and heat generation of the electric motor that drives the pump, if the difference between the pump discharge pressure and the suction pressure is large, the swash plate angle θ is decreased according to the pressure difference. Control techniques for making them known are known.

  In the invention described in Patent Document 1, in the variable displacement hydraulic motor, there is a difference between the flow rate change rate when the flow rate of the variable displacement hydraulic motor is increased and the flow rate change rate when the flow rate is decreased. Is provided. According to the invention described in Patent Document 1, it can be made difficult to be affected by the vibration of external force.

  Patent Document 2 discloses a technique for temporarily increasing the absorption horsepower in the pump by delaying the decrease in the swash plate angle θ in the axial piston pump.

  Patent Document 3 discloses a technique that uses an oil pressure discharged from its own pump as a driving force for swash plate control in an axial piston pump. Furthermore, in the pump swash plate angle control method described in Patent Document 3, swash plate control is performed to reduce the discharge flow rate based on the pressure difference between the discharge side and the suction side.

  Patent Document 4 is an invention relating to a pump that controls the discharge flow rate according to a constant horsepower curve. In the regulator circuit described in Patent Document 4, even if the discharge flow rate suddenly increases at high pressure, the decrease in the discharge flow rate is delayed as long as the engine that is the pump drive source has a flywheel effect. Yes.

Japanese Patent No. 3712296 Japanese Patent No. 3707742 Japanese Patent No. 4022032 Japanese Patent Publication No.59-26796

An object of the present invention is the fluid pressure actuator, to improve the responsiveness when performing forward and reverse motion within a short period of time, it is to provide a fluid pressure pump.

  The means for solving the problem will be described below using the numbers used in the (DETAILED DESCRIPTION). These numbers are added to clarify the correspondence between the description of (Claims) and (Mode for Carrying Out the Invention). However, these numbers should not be used to interpret the technical scope of the invention described in (Claims).

  A swash plate angle control device (300) according to the present invention is a device that controls the swash plate angle using the discharge pressure of the variable displacement pump (302) itself, and includes a check valve (62) and an orifice (60). The swash plate angle control speed is changed according to the control direction.

  The swash plate angle control device (100, 100 ′, 200) according to the present invention includes a first supply / discharge port (25) and a second supply / discharge port (26) of the bidirectional variable displacement pump (2) itself. In a device for controlling the swash plate angle using the discharge pressure of the high-pressure side supply / discharge port, a check valve (62) and an orifice (60) are provided, and the swash plate angle control speed is changed according to the control direction. It is.

  In the swash plate angle control device (100, 100 ′) according to the present invention, a shuttle valve (7) is disposed between the flow paths of the first supply / discharge port (25) and the second supply / discharge port (26). The swash plate angle is controlled using the output of the shuttle valve (7).

  The swash plate angle control device (200) according to the present invention includes the first supply / discharge port (25), the swash plate angle control device (200), the second supply / discharge port (26), and the swash plate angle. A pressure detection check valve (207) is arranged between the flow paths of the control device (200), and the first supply / exhaust port (25) and the second supply / exhaust port (26) are arranged on the high-pressure side. The swash plate angle is controlled using the discharge pressure of the supply / discharge port.

  Further, the swash plate angle control device (100, 100 ′, 200, 300) according to the present invention is used when the discharge pressure of the variable displacement pump (2, 302) itself for controlling the swash plate angle is less than a predetermined pressure. A compensator valve (6) is provided for setting the first state and setting the second state when the pressure is equal to or higher than a predetermined pressure, and when transitioning from the first state to the second state, Different swash plate angle control speeds are set when transitioning to the first state.

  The check valve (62) of the swash plate angle control device (100, 100 ′, 300) opens when the discharge flow rate of the variable displacement pump (2, 302) is increased, and decreases the discharge flow rate. Closed configuration.

  ADVANTAGE OF THE INVENTION According to this invention, the swash plate angle control apparatus of the hydraulic pressure pump which improves the responsiveness of the normal / reverse motion of the actuator controlled with the working fluid which a pump discharges is small and lightweight.

FIG. 1 is a block diagram including a swash plate angle control apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the differential pressure between the discharge side pressure and the suction side pressure of the pump and the discharge flow rate in the fluid pressure actuator. FIG. 3 is a side sectional view of the fluid pressure actuator. 4 is a cross-sectional view taken along the line AA ′ in FIG. 5 is a cross-sectional view taken along the line BB ′ in FIG. FIG. 6 is a block diagram including a swash plate angle control device according to the second embodiment of the present invention. FIG. 7 is a block diagram including a swash plate angle control device according to the third embodiment of the present invention. FIG. 8 is a block diagram including a swash plate angle control device according to the fourth embodiment of the present invention.

(First embodiment)
A swash plate angle control apparatus for an axial piston variable displacement pump according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram including a swash plate angle control device 100 according to the first embodiment of the present invention. FIG. 1 shows an electric motor 1, a variable displacement pump 2, an output cylinder 3, a swash plate control cylinder 5, a compensator valve 6, a shuttle valve 7, an output piston position sensor 8, and a motor speed sensor 9. The first output cylinder flow path 14, the second output cylinder flow path 15, the return flow path 16, the control device 17, the first swash plate control flow path 55, the second swash plate control flow path 56, A third swash plate control flow path 57, an orifice 60 and a check valve 62 are described. Among them, the swash plate angle control device 100 includes a swash plate control cylinder 5, a compensator valve 6, a shuttle valve 7, an orifice 60, and a check valve 62 as main components. Here, for the sake of explanation, the form in which the output cylinder 3 is connected is shown. However, in place of the output cylinder 3, a form in which a plurality of cylinders are arranged in parallel or in series, or a form in which a hydraulic motor is arranged is also used. The effect by application of the invention can be similarly expected.

  The output cylinder 3 includes a first output cylinder chamber 31, a second output cylinder chamber 32, and an output piston 33 disposed between the first output cylinder chamber 31 and the second output cylinder chamber 32. When the working fluid is supplied to the first output cylinder chamber 31 and discharged from the second output cylinder chamber 32, the output piston 33 moves in the right direction shown in FIG. When the working fluid is supplied to the second output cylinder chamber 32 and discharged from the first output cylinder chamber 31, the output piston 33 moves to the left as shown in FIG. The working fluid is, for example, oil.

  The variable displacement pump 2 includes a first supply / discharge port 25, a second supply / discharge port 26, and a swash plate 27 that changes the discharge flow rate of the variable displacement pump 2. The electric motor 1 drives the variable displacement pump 2. When the electric motor 1 rotates in the first direction, the variable displacement pump 2 discharges the working fluid sucked from the second supply / discharge port 26 from the first supply / discharge port 25. When the electric motor 1 rotates in the second direction opposite to the first direction, the variable displacement pump 2 discharges the working fluid sucked from the first supply / discharge port 25 from the second supply / discharge port 26.

  The swash plate angle θ of the swash plate 27 is driven and controlled by the pressure generated by the variable displacement pump 2 itself. By adopting such a configuration, another power source for driving the swash plate 27 becomes unnecessary. Therefore, the size and weight of the fluid pressure actuator can be reduced. Therefore, the fluid pressure actuator is suitable for use in an aircraft or the like.

  The first output cylinder flow path 14 connects the first supply / discharge port 25 and the first output cylinder chamber 31. The second output cylinder passage 15 connects the second supply / exhaust port 26 and the second output cylinder chamber 32. The return flow path 16 stores the working fluid leaked from the variable capacity pump 2 in the accumulator 4 connected to the return flow path 16. The working fluid stored in the accumulator 4 is returned to the first output cylinder flow path 14 via the check valve 11 when the pressure of the return flow path 16 exceeds the pressure of the first output cylinder flow path 14. The working fluid stored in the accumulator 4 is returned to the second output cylinder flow path 15 via the check valve 11 when the pressure of the return flow path 16 exceeds the pressure of the second output cylinder flow path 15.

  The swash plate control cylinder 5 includes a first cylinder chamber 51, a second cylinder chamber 52, a swash plate control piston 53 disposed between the first cylinder chamber 51 and the second cylinder chamber 52, and a spring 54. ing. The swash plate control piston 53 is connected to the swash plate 27. When the working fluid is supplied to the first cylinder chamber 51 and discharged from the second cylinder chamber 52, the swash plate control piston 53 moves downward as shown in FIG. When the working fluid is supplied to the second cylinder chamber 52 and discharged from the first cylinder chamber 51, the swash plate control piston 53 moves upward as shown in FIG. The spring 54 biases the swash plate control piston 53 upward as shown in FIG.

  When the swash plate control piston 53 moves upward as shown in FIG. 1, the discharge flow rate of the variable displacement pump 2 increases. When the swash plate control piston 53 moves downward as shown in FIG. 1, the discharge flow rate of the variable displacement pump 2 decreases. When the swash plate control piston 53 is at the upper end position shown in FIG. 1, the discharge flow rate of the variable displacement pump 2 is maximum, and when it is at the lower end position, the discharge flow rate of the variable displacement pump 2 is minimum. It becomes.

  The first swash plate control flow path 55 connects the first cylinder chamber 51 and the switching port of the compensator valve 6. In the first swash plate control flow path 55, an orifice 60 and a check valve 62 are arranged.

  The third swash plate control flow path 57 connects the shuttle valve 7, the switching port of the compensator valve 6, and the pilot port 6P.

  The shuttle valve 7 is a valve that supplies the working fluid to the third swash plate control channel 57 from the higher pressure in the first output cylinder channel 14 and the second output cylinder channel 15. Instead of the shuttle valve 7, two check valves can be used (see FIG. 7).

  A piston position command value L * indicating the target position of the output piston 33 is input to the control device 17. The output piston position sensor 8 detects the position of the output piston 33 and outputs a piston position detection value Ls to the control device 17. The motor speed sensor 9 detects the rotation speed of the electric motor 1 and outputs a motor speed detection value ωs to the control device 17.

The compensator valve 6 sets the first state when the discharge pressure of the variable displacement pump 2 (pressure of the third swash plate control flow path 57 ) is less than a predetermined pressure difference, and sets the first state when the discharge pressure is greater than the predetermined pressure difference. Set 2 states.

(Description of the first state)
In the first state, the compensator valve 6 connects the first swash plate control channel 55 and the return channel 16, and the third swash plate control channel 57 is shielded. In this state, the pressure in the first cylinder chamber 51 of the swash plate control cylinder 5, the pressure in the second cylinder chamber 52, and the pressure in the return flow path 16 are equal. As a result, the swash plate control piston 53 is positioned at the upper end shown in FIG. 1 by the biasing force of the spring 54, and the discharge flow rate of the variable displacement pump 2 is maximized.

(Description of the second state)
In the second state, the compensator valve 6 connects the first swash plate control channel 55 and the third swash plate control channel 57, and the return channel 16 is shielded. In this state, the high pressure in the third swash plate control flow path 57 is transmitted to the first cylinder chamber 51 of the swash plate control cylinder 5 via the compensator valve 6. The pressure in the second cylinder chamber is the pressure in the return flow path 16 connected thereto. The swash plate control piston 53 that determines the angle of the swash plate 27 moves to a position where the pressure of the first cylinder chamber 51, the pressure of the second cylinder chamber, and the biasing force of the spring 54 are balanced.

(Description of transition from the first state to the second state)
When the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 increases and the state transitions from the first state to the second state, the compensator valve 6 causes the first swash plate control flow path 55 and the third swash plate control flow. The path 57 is connected, and the return path 16 is shielded. At this time, the working fluid flows from the third swash plate control flow path 57 that is at a high pressure to the first swash plate control flow path 55. Then, the working fluid flows into the first cylinder chamber 51 via the orifice 60 disposed in the first swash plate control flow path 55. At this time, the working fluid cannot pass through the check valve 62 due to the check function of the check valve 62. Accordingly, since the working fluid flowing into the first cylinder chamber 51 is only the working fluid that has passed through the orifice 60 having a large resistance during flow, the flow rate is small. Accordingly, the swash plate control piston 53 moves slowly downward as shown in FIG. 1 and the swash plate angle θ gradually decreases, so the swash plate angle control speed decreases. Then, the discharge flow rate of the variable displacement pump 2 also gradually decreases.

(Description of transition from second state to first state)
When the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 becomes small and the state transitions from the second state to the first state, the compensator valve 6 causes the first swash plate control flow path 55 and the return flow path 16 to pass through. The third swash plate control flow path 57 is shielded. At this time, the working fluid flowing out from the first cylinder chamber 51 of the swash plate control cylinder 5 mainly flows through the flow path of the check valve 62 with low resistance during flow and flows into the return flow path 16. Accordingly, since the swash plate control piston 53 moves in the upward direction shown in FIG. 1 at a relatively high speed, the swash plate angle control speed is improved, and the discharge flow rate of the variable displacement pump 2 increases relatively quickly.

  When the second state continues only for a short time, a load is continuously applied to the electric motor 1 as the discharge flow rate of the variable displacement pump 2 is set to be large. However, when the piston position command value L * is applied to the output piston 33 so as to switch between the left direction driving and the right direction driving shown in FIG. 1 within a short time, the swash plate angle θ is maintained in a large state. By doing so, the discharge flow rate of the variable displacement pump 2 is also large, and the output piston 33 of the output cylinder 3 can be quickly reversed. Therefore, by arranging the orifice 60 in the first swash plate control flow path 55, the response of the output piston 33 when the electric motor 1 is reversed can be improved.

  When the second state lasts for a long time, the swash plate angle θ gradually decreases to around 0 degrees. Therefore, the load applied to the electric motor 1 is reduced, and it is possible to suppress power consumption and heat generation.

  When the rotation of the electric motor 1 is reversed in the second state, the pressure in the third swash plate control flow path 57 and the pilot port 6P decreases, and the compensator valve 6 transitions to the first state. Then, the first swash plate control channel 55 and the return channel 16 are connected.

  Conventionally, when the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 is increased, the swash plate angle θ is suddenly increased regardless of the holding time of the second state in order to reduce the load of the electric motor 1. Was reduced to around 0 degrees. However, if the rotation of the electric motor 1 is reversed from this state, a predetermined time is required until the discharge flow rate becomes maximum. Therefore, the reversing operation of the output piston 33 is delayed, resulting in poor responsiveness. .

  By using the swash plate angle control device 100 of the variable displacement pump 2 according to the present invention, even if the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 becomes large, the decrease in the swash plate angle θ is delayed. Thus, the discharge flow rate of the variable displacement pump 2 can be maintained to some extent. Therefore, when the rotation of the electric motor 1 is reversed, it is possible to improve the disadvantage that the discharge flow rate is temporarily insufficient. And the responsiveness at the time of the reversing operation | movement of the output piston 33 can be improved.

  Next, the relationship between the pressure difference of the static variable displacement pump 2 and the discharge flow rate will be described with reference to FIG.

  The horizontal axis in FIG. 2 represents the pressure difference ΔP between the discharge pressure of the variable displacement pump 2 and the suction pressure. When the pressure difference ΔP increases beyond the prescribed pressure difference ΔP3, the compensator valve 6 shown in FIG. 1 shifts from the first state to the second state, and starts limiting the discharge flow rate and pressure in the variable displacement pump 2. To do. Then, due to the action of the swash plate control cylinder 5, the discharge flow rate starts to decrease according to the pressure. When the pressure difference reaches the pressure ΔP4, the discharge flow rate becomes zero. The gradient, which is the relationship between the pressure difference and the discharge flow rate, can be set according to the characteristics of the compensator valve 6 and the spring 54 as required.

  When the pressure difference between the discharge pressure of the variable displacement pump 2 and the suction pressure becomes ΔP5, the discharge flow rate of the variable displacement pump 2 becomes the discharge flow rate Qa at the point A shown in FIG.

  Next, the structure of the fluid pressure actuator will be described with reference to FIGS. FIG. 3 is a side sectional view of the variable displacement pump 2 and the output cylinder 3. 4 is a cross-sectional view taken along line AA ′ of FIG. FIG. 5 is a cross-sectional view taken along the line BB ′ of FIG. In addition, about the structure which has the same function as the structure shown in FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The variable displacement pump 2 includes a cylinder block 21 and a valve plate 24. The cylinder block 21 includes a plurality of cylinder chambers 22 and a pump piston 23 that increases or decreases the volume of each of the plurality of cylinder chambers 22. The pump piston 23 is configured to maintain a contact state with the swash plate 27. The electric motor 1 rotates the cylinder block 21. The valve plate 24 includes a first supply / discharge port 25 and a second supply / discharge port 26. As shown in FIG. 4, the first supply / discharge port 25 and the second supply / discharge port 26 are formed to be 180-degree rotationally symmetric with respect to the rotation axis. As shown in FIG. 5, the plurality of cylinder chambers 22 are arranged at equiangular intervals on a circumference around the rotation axis. A gap is provided between the cylinder block 21 and the valve plate 24.

  The cylinder chamber 22, and the first supply / exhaust port 25 and the second supply / exhaust port 26 face each other through a gap. When the cylinder block 21 is rotated by the electric motor 1, the pump piston 23 is guided by the surface of the swash plate 27 and moves forward and backward in the rotation axis direction. The advance / retreat cycle of the pump piston 23 is equal to the rotation cycle of the cylinder block 21. As the pump piston 23 advances and retreats, the volume of the cylinder chamber 22 increases or decreases.

  The first supply / discharge port 25 is provided so as to face the cylinder chamber 22 whose volume is decreasing when the electric motor 1 rotates in the first direction. The second supply / exhaust port 26 is provided to face the cylinder chamber 22 whose volume is increasing when the electric motor 1 rotates in the first direction. In this case, when the electric motor 1 rotates in the second direction, the first supply / discharge port 25 faces the cylinder chamber 22 whose volume is increasing, and the second supply / discharge port 26 faces the cylinder chamber 22 whose volume is decreasing. To do.

  The swash plate angle θ shown in FIG. 3 is 0 degree when the swash plate 27 is perpendicular to the rotation axis of the cylinder block 21. When the swash plate angle θ is large, the discharge flow rate of the variable displacement pump 2 increases. When the swash plate angle θ is small, the discharge flow rate of the variable displacement pump 2 is small.

  The swash plate control piston 53 of the swash plate control cylinder 5 is connected to the swash plate 27. The swash plate control cylinder 5 is an actuator for changing the swash plate angle θ.

(Second Embodiment)
Next, another embodiment of the swash plate angle control device of the variable displacement pump will be described with reference to FIG. In the swash plate angle control device 100 shown in FIG. 1, the orifice 60 and the check valve 62 are arranged in the first swash plate control flow path 55. On the other hand, in the swash plate angle control device 100 ′ shown in FIG. 6, the orifice 60 and the check valve 62 are arranged in the second swash plate control flow path 56 communicating with the second cylinder chamber 52.

(Description of transition from second state to first state)
The first state and the second state of the compensator valve 6 are the same as those defined in the first embodiment. When the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 becomes small and the state transitions from the second state to the first state shown in FIG. 6, the compensator valve 6 has the first swash plate control flow path 55 and the return flow path. 16, the third swash plate control flow path 57 is shielded. At this time, the working fluid flowing into the second cylinder chamber 52 of the swash plate control cylinder 5 mainly passes from the return flow path 16 through the flow path of the check valve 62 with low resistance during flow. Accordingly, since the swash plate control piston 53 moves in the upward direction shown in FIG. 1 at a relatively high speed, the swash plate angle control speed is improved, and the discharge flow rate of the variable displacement pump 2 increases relatively quickly.

(Description of transition from the first state to the second state)
When the difference between the discharge pressure and the suction pressure of the variable displacement pump 2 increases and the state transitions from the first state to the second state, the compensator valve 6 has the first swash plate control flow path 55 and the third swash plate control flow path. 57 and the return channel 16 is shielded. At this time, the working fluid flows from the third swash plate control flow path 57, which is at a high pressure, to the first swash plate control flow path 55, and operates from the second cylinder chamber 52 to the second swash plate control flow path 56. Fluid is discharged. At this time, since the working fluid cannot pass through the check valve 62 due to the check function of the check valve 62, the working fluid discharged from the second cylinder chamber 52 passes through the orifice 60. Accordingly, since the flow rate of the working fluid discharged from the second cylinder chamber 52 is kept low, the swash plate control piston 53 moves slowly downward as shown in FIG. 1, and the swash plate angle θ gradually decreases. As a result, the swash plate angle control speed decreases. As a result, the discharge flow rate of the variable displacement pump 2 gradually decreases.

  As described above, even when the swash plate angle control device 100 ′ shown in FIG. 6 is used, the flow rate change rate when the discharge flow rate of the variable displacement pump 2 is increased and the flow rate change rate when it is reduced. A difference can be made between. And the responsiveness at the time of performing the forward / reverse motion of swash plate angle control apparatus 100 'within a short time can be improved.

(Third embodiment)
Next, another embodiment of the swash plate angle control device of the variable displacement pump will be described with reference to FIG. In addition, about the structure which has the same function as the structure shown in FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. The difference between the swash plate angle control device 100 shown in FIG. 1 and the swash plate angle control device 200 shown in FIG. 7 is that two pressure detection check valves 207 are arranged in place of the shuttle valve 7. In addition, an embodiment in which the direction of the check valve 62 is changed is also shown.

(About the pressure detection check valve 207)
In the embodiment shown in FIG. 7, the first supply / discharge port 25 of the variable displacement pump 2 and the third swash plate control flow path 57 of the swash plate angle control device 200 are connected by the first pressure detection check valve 207. doing. Similarly, the second supply / exhaust port 26 and the third swash plate control flow path 57 are connected by a second pressure detection check valve 207. Also by using this configuration, the swash plate angle can be controlled using the discharge pressure of the high-pressure side supply / exhaust port of the first supply / exhaust port 25 and the second supply / exhaust port 26.

(Direction of check valve 62)
In the swash plate angle control device 100 shown in FIG. 1, the check valve 62 is opened when the discharge flow rate of the variable displacement pump 2 is increased, and the check valve 62 is closed when the discharge flow rate is decreased. there were. On the other hand, in the swash plate angle control device 200 shown in FIG. 7, the check valve 62 is closed when the discharge flow rate of the variable displacement pump 2 is increased, and the check valve 62 is set when the discharge flow rate is decreased. It is an open configuration. By using the configuration shown in FIG. 7, the swash plate angle control speed when the discharge flow rate of the variable displacement pump 2 increases can be reduced. Further, the swash plate angle control speed when the discharge flow rate decreases can be increased.

(Fourth embodiment)
Next, another embodiment of the swash plate angle control device of the variable displacement pump will be described with reference to FIG. In addition, about the structure which has the same function as the structure shown in FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted. In the swash plate angle control apparatus 100 shown in FIG. 1, the embodiment using the bidirectional rotary variable displacement pump 2 including the first supply / discharge port 25 and the second supply / discharge port 26 has been described. On the other hand, the swash plate angle control device 300 shown in FIG. 8 shows an embodiment using a variable displacement pump 302 having one discharge port 325. In the embodiment shown in FIG. 8, a general actuator 303 is controlled instead of the output cylinder 3.

  As shown in FIG. 8, the working fluid discharged from the discharge port 325 of the variable displacement pump 302 is supplied to the actuator 303 via the output cylinder flow path 314, and at the same time, the third of the swash plate angle control device 300. The swash plate control flow path 57 is supplied.

(Description of transition from second state to first state)
The first state and the second state of the compensator valve 6 shown in FIG. 8 are the same as the definitions in the first embodiment. The compensator valve 6 connects the first swash plate control flow path 55 and the return flow path 16 when the discharge pressure of the variable displacement pump 302 decreases and the state changes from the second state to the first state shown in FIG. The third swash plate control flow path 57 is shielded. At this time, the working fluid flowing out from the first cylinder chamber 51 of the swash plate control cylinder 5 mainly flows through the flow path of the check valve 62 with low resistance during flow and flows into the return flow path 16. Accordingly, since the swash plate control piston 53 moves in the upward direction shown in FIG. 8 at a relatively high speed, the swash plate angle control speed is improved and the discharge flow rate of the variable displacement pump 302 increases relatively fast.

(Description of transition from the first state to the second state)
When the discharge pressure of the variable displacement pump 302 increases and the state transitions from the first state to the second state, the compensator valve 6 connects the first swash plate control channel 55 and the third swash plate control channel 57. The return channel 16 is shielded. At this time, the working fluid flows from the third swash plate control flow path 57 that is at a high pressure to the first swash plate control flow path 55. Then, the working fluid flows into the first cylinder chamber 51 via the orifice 60 disposed in the first swash plate control flow path 55. At this time, the working fluid cannot pass through the check valve 62 due to the check function of the check valve 62. Accordingly, since the working fluid flowing into the first cylinder chamber 51 is only the working fluid that has passed through the orifice 60 having a large resistance during flow, the flow rate is small. Accordingly, the swash plate control piston 53 moves slowly downward as shown in FIG. 8 and the swash plate angle θ gradually decreases, so the swash plate angle control speed decreases. Then, the discharge flow rate of the variable displacement pump 2 also gradually decreases.

  As described above, even if the swash plate angle control device 300 shown in FIG. 8 is used, the flow rate change rate when the discharge flow rate of the variable displacement pump 302 is increased and the flow rate change rate when it is decreased. Differences can be made between.

100, 100 ', 200, 300 ... Swash plate angle control device 1 ... Electric motor 2, 302 ... Variable displacement pump 3 ... Output cylinder 4 ... Accumulator 5 ... Swash plate control cylinder 6 ... Compensator valve 6P ... Pilot port 7 ... Shuttle valve DESCRIPTION OF SYMBOLS 14 ... 1st output cylinder flow path 15 ... 2nd output cylinder flow path 16 ... Return flow path 25 ... 1st supply / discharge port 26 ... 2nd supply / discharge port 27 ... Swash plate 31 ... 1st output cylinder chamber 32 ... 2nd Output cylinder chamber 33 ... output piston 51 ... first cylinder chamber 52 ... second cylinder chamber 53 ... swash plate control piston 54 ... spring 55 ... first swash plate control channel 56 ... second swash plate control channel 57 ... third Swash plate control flow path 60 ... Orifice 62 ... Check valve 207 ... Pressure detection check valve

Claims (7)

A variable capacity pump connected to a return flow path and provided with a swash plate and having a first supply / discharge port and a second supply / discharge port for supplying and discharging fluid at a pressure depending on an angle of the swash plate; The fluid leaked from the variable capacity pump flows through the flow path, and the first supply / discharge port and the second supply / discharge port are connected to the first output channel and the second output channel, respectively.
Of the second output flow path and the first output channel, said high pressure side so as to control the angle of the swash plate based on the pressure of the discharge pressure is high high-pressure channel and the pressure in the return channel A swash plate angle control device provided between the flow path and the return flow path ;
With
The swash plate angle control device includes a swash plate control cylinder,
The swash plate control cylinder is
A first cylinder chamber connected to the first swash plate control flow path connected to the high pressure side flow path or the return flow path ;
A second cylinder chamber connected to the second swash plate control flow path connected to the return flow path and provided with a spring;
An angle of the swash plate is provided between the first cylinder chamber and the second cylinder chamber, coupled to the swash plate, and based on the pressure of the first cylinder chamber and the pressure of the second cylinder chamber. To change the swash plate control piston and
With
The swash plate angle control device includes a parallel arrangement of a check valve and an orifice provided in one of the first swash plate control flow path and the return flow path so as to change the control speed of the swash plate angle according to the control direction. Further connection
Fluid pressure pump. The fluid pressure pump according to claim 1,
The fluid pressure pump is
Provided between the first output flow path and the second output flow path, one of the first output flow path and the second output flow path is connected to the high-pressure side flow based on the discharge pressure of the variable displacement pump. Further provided with a shuttle valve to select as a path
Fluid pressure pump . The fluid pressure pump according to claim 1 or 2,
The swash plate angle control device comprises:
Connected to the first swash plate control flow path, the return flow path, and the high pressure side flow path, and the first state is set when the pressure of the high pressure side flow path is less than a first predetermined pressure. And further comprising a compensator valve for setting the second state when the pressure exceeds the first predetermined pressure ,
The compensator valve connects the first swash plate control flow path to the return flow path in the first state, shields the high pressure side flow path, and in the second state, Connect to the first swash plate control flow path
Fluid pressure pump . In the fluid pressure pump according to claim 3,
A parallel connection of the check valve and the orifice is provided in the middle of the first swash plate control flow path,
The check valve allows a fluid flow from the first cylinder chamber to the return flow channel in the first state, and a fluid flow from the high-pressure side flow channel to the first cylinder chamber in the second state. It is provided in the direction to prevent
Fluid pressure pump . In the fluid pressure pump according to claim 3,
A parallel connection of the check valve and the orifice is provided in the middle of the second swash plate control flow path,
The check valve is provided in a direction that prevents the flow of fluid from the second cylinder chamber to the return flow path and allows the flow of fluid from the return flow path to the second cylinder chamber.
Fluid pressure pump . In the fluid pressure pump according to claim 3,
A parallel connection of the check valve and the orifice is provided in the middle of the first swash plate control flow path,
The check valve blocks the flow of fluid from the first cylinder chamber to the return channel in the first state, and prevents fluid from flowing from the high-pressure side channel to the first cylinder chamber in the second state. It is provided in a direction that allows flow
Fluid pressure pump . The fluid pressure pump according to any one of claims 1 to 6,
A first check valve provided between the return flow path and the first output flow path in a direction allowing fluid flow from the return flow path to the first output flow path;
A fluid pressure pump further comprising a second check valve provided between the return channel and the second output channel in a direction allowing fluid flow from the return channel to the second output channel. .

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