JP4469076B2 - Capacity controller for variable displacement fluid machinery - Google Patents

Description

[0001]
[Industrial technical field]
The present invention relates to a displacement control device for a variable displacement fluid machine that varies the displacement by changing the stroke of a piston, and more particularly to a displacement control device for a variable displacement fluid machine that is made compact.
[0002]
[Prior art]
A general variable displacement swash plate type pump has a cylinder block that rotates integrally with a shaft in a housing, is arranged around the rotation axis of the cylinder block, and is sequentially parallel to the axis of the shaft. The head of the reciprocating piston moves on the swash plate fixed in the housing as the shaft rotates. The fluid discharge amount is adjusted by adjusting the swash plate angle of the swash plate. The variable capacity swash plate motor has the same structure, and the operation is only reversed, and the displacement volume is adjusted by adjusting the swash plate angle of the swash plate.
[0003]
This type of variable displacement pump or variable displacement fluid machine of a variable displacement motor has a servo piston connected and fixed to a swash plate, and pump discharge pressure oil output from a control valve is supplied to the pressure receiving chamber of the servo piston. The discharge amount or the displacement volume is controlled by operating by shutting off and tilting the swash plate.
[0004]
An example of a displacement control device for this variable displacement pump is disclosed in, for example, Japanese Patent No. 2542265. The capacity control device disclosed in the publication includes a servo piston connected and fixed to a swash plate inside the pump body. A case body of a control valve that operates in a direction substantially parallel to the servo piston is fixed to the upper portion of the pump body. The servo piston is disposed substantially at the center of the pump body, and the control valve is disposed above the servo piston and is offset laterally from the substantially center of the pump body.
[0005]
The large-diameter pressure receiving chamber of the servo piston is communicated with and cut off from the pump discharge passage by the control valve, and the small-diameter pressure receiving chamber of the servo piston is always in communication with the pump discharge passage. When the pump discharge pressure is not applied, the control valve moves the spool to the drain position (blocking position) by the spring force of the spring, and resists the spring force of the spring when the pump discharge pressure is applied. The spool moves to the communication position.
[0006]
In this conventional capacity control device, when the pump discharge pressure becomes high, the control valve is moved to the communication position against the spring force of the spring, and the pump discharge pressure is transferred to the large-diameter pressure receiving chamber via the pump discharge path. Supply oil. The servo piston is moved in the small swash plate angle direction (small capacity direction) to reduce the pump discharge amount. When the set load of the spring increases, the control valve is moved toward the shut-off position to balance the pump discharge pressure and the spring pressure.
[0007]
When the pump discharge pressure is lowered, the communication area between the large-diameter pressure receiving chamber and the pump discharge passage is reduced, and the control valve is moved to the cutoff position. The servo piston moves in the capacity increasing direction to increase the pump discharge amount. The spring set load is reduced to balance the pump discharge pressure and the spring pressure. By repeating this operation, the product (horsepower) of the pump discharge amount and the pump discharge pressure is controlled to be constant, and the pump is controlled with equal horsepower.
[0008]
A first lever is pivotally supported on the case body so as to be swingable about a horizontal axis, and a housing is interposed between the tip of the first lever and the spring end to control the movement of the first lever. I tell the spring through. Further, a second lever is pivotally supported on the horizontal axis so as to be swingable with a predetermined distance from the first lever and substantially perpendicular to the lever. Therefore, the first lever and the second lever are arranged on parallel vertical surfaces that are separated from each other. The length of the second lever is set longer than that of the first lever. A roller is provided at the tip of the second lever, and the roller is brought into contact with the tip cam surface of the rocker cam protruding from the servo piston. In order to make the difference between the hydraulic pressure received by the large-diameter pressure receiving chamber side of the servo piston and the hydraulic pressure and spring force received by the small-diameter pressure receiving chamber side constant via the first lever and the second lever, the spool of the control valve and the servo The swash plate angle of the hydraulic pump is controlled by moving the piston relatively.
[0009]
[Problems to be solved by the invention]
In the capacity control device disclosed in the above-mentioned Japanese Patent No. 2542265, the control valve is displaced to the upper lateral side of the servo piston in order to prevent the lever from interfering with the control valve or the spring. Thus, the servo piston and the control valve must be interlocked with each other through the two first and second levers. As a result, as described above, the first and second levers must be supported on the same horizontal axis with an interval.
[0010]
In order to accommodate the first lever and the second lever in the same case body, the lateral width of the case body installed on the pump body must be increased, and the size must be increased. In addition, since the capacity control device has to mechanically interpose the housing between the tip of the first lever and the spring as described above, the case body that accommodates these parts must naturally be long. It is forced to enlarge even more. Therefore, it is difficult to make the whole pump compact.
[0011]
In addition, since the first and second levers extend so as to intersect each other via a horizontal axis, it is difficult to adjust each component such as the servo piston, the control valve, the spring, and the housing. When used for a long time under harsh conditions, wear, friction, scratches, etc. occur between the parts of the servo piston cam, the first and second levers, the housing, etc., and the initial capacity control accuracy is improved. Difficult to maintain.
[0012]
The present invention has been made to solve such conventional problems, and its specific object is to achieve a reduction in size and cost, and a variable capacity fluid that has a simple structure and improved capacity characteristics. It is to provide a capacity control device for a machine.
[0013]
[Means for solving the problems and effects]
Book Wish The invention according to claim 1 is directed to the movement amount of the servo piston. Depending on, A displacement control device for a variable displacement fluid machine for controlling a displacement, comprising a control valve for controlling a movement amount of the servo piston, the control valve being arranged in parallel with an operation direction of the servo piston, and a pump A spool that switches to the communication position and drain position by the discharge pressure oil, and the tip of the spool Directly And provided springs, The servo piston has a lock cam that moves in a cavity formed in a body of the variable displacement fluid machine, Identical including the servo piston and control valve actuation axis Vertical On the plane, The upper end portion has a swing shaft, and has a single lever made of an elongated plate member swinging in the same direction as the servo piston operation direction around the swing shaft. A substantially square shape having a bent portion that is on a plane and bends toward the control valve, and a part of the end surface of the bent portion opposite to the bending direction is in contact with the lock cam, The tip of the spring of the control valve is in contact with a part of the end surface of the bent portion on the opposite side, In the capacity control device of the variable capacity fluid machine,
[0014]
Here, in the variable capacity fluid machine according to the present invention, for example, a cylinder block fixed to a rotatable shaft as an input shaft is disposed in the housing, and the same axial direction as the shaft is disposed in the cylinder block. A plurality of pistons arranged so as to be reciprocally movable can change a stroke according to an inclination angle of a swash plate fixed in the housing so that an inclination angle with respect to the shaft can be adjusted. Mention may be made of a swash plate type piston pump.
[0015]
Another variable displacement fluid machine of the present invention is a swash plate type piston motor of the same type as the pump. The swash plate type piston motor performs a motor action by applying torque to the shaft through the cylinder block by the force of the piston reciprocating in the cylinder block pressing the swash plate. When the tilt angle of the swash plate is increased, the motor rotates at a low speed with a large torque, and when the tilt angle is decreased, the torque decreases and the motor rotates at a high speed.
[0016]
In the present invention, the control valve is arranged in parallel with the operation direction of the servo piston, and the lever is arranged on the same plane including both the servo piston and the operation axis of the control valve. The servo piston and the control valve are interlocked with each other by swinging the lever.
[0017]
As described above, since the single lever is arranged on the same plane including both the servo piston and the operation axis of the control valve, the lever is prevented from interfering with the control valve, the spring, etc. as in the prior art. In addition, it is not necessary to place the control valve at a position displaced laterally above the servo piston so that the two first and second levers are supported on the same horizontal axis at an interval. That is, in order to transmit the operation between the spool of the control valve and the servo piston, it is not necessary to arrange two levers in the width direction in the control valve, and the single lever makes the operation smooth and mutually. In addition to being able to transmit accurately, the control valve case body can be shortened in the width direction perpendicular to the direction of operation, leading to a reduction in the capacity control device and, in turn, achieving a more compact fluid machine. Can contribute.
[0018]
Furthermore, according to the present invention, the housing disposed between the first lever and the spring end in the capacity control device disclosed in the above publication is eliminated, and a part of a single lever is in direct contact with the spring end. Therefore, the capacity control device can be shortened in the length direction.
[0019]
In addition, as in the prior art, two levers are arranged apart from each other in the width direction of the control valve, and one lever is disposed opposite to the servo piston provided at the center of the fluid machine body, while the other lever If the servo piston is arranged on the end side of the fluid machine main body, is the length of one lever set longer than the other lever? The installation location of the control valve and the spring is changed, or the size of the fluid machine main body is changed, which tends to increase the size of the entire fluid machine. On the other hand, since the lever of the present invention adopts the above-described configuration, it is arranged within a set size range corresponding to the size of the fluid machine main body without requiring a design change of the existing fluid machine main body. In addition, it is possible to obtain a capacity control device having an optimal capacity characteristic with a simple structure and a constant horsepower without increasing the number of parts.
[0020]
Furthermore, the present invention can simplify the structure without increasing the number of parts without using two levers as in the prior art, thereby preventing an increase in the number of assembly steps and the complication of the work of adjusting the mounting between the parts. can do.
[0021]
The invention according to claim 2 stipulates that the lever and the servo piston are in contact via a ball.
According to the present invention, since the lever and the servo piston are brought into contact with each other via the ball, in addition to the function and effect of the first aspect, abnormal wear or damage caused by abrasion is caused in the contact portion. It can be prevented in advance. Compared with the conventional capacity control device, since the displacement of the servo piston can be transmitted to the lever by a ball without using a roller as a part contacting the cam surface, wear can be reduced and durability can be improved. it can.
[0022]
According to a third aspect of the present invention, the spring is a compression spring, and a spring support portion extended from the distal end portion of the spool is inserted into the spring, and the base end of the spring is supported by the spring support portion. Support.
According to this invention, since the spring support portion extended at the tip of the spool is inserted into the spring and the base end of the spring is supported by the spring support portion, the space inside the spring is effectively used. It can be used and its expansion and contraction can be performed smoothly, and the spring characteristic is effectively exhibited to ensure the correct operation of the control valve.
[0023]
The spring is, for example, a coil spring arranged in multiple stages, or an illegal pitch coil spring having a constant coil diameter or wire diameter and changing the pitch, a cone or barrel having a constant wire diameter and changing the coil diameter, etc. Compression coil springs having different spring constants such as non-linear springs can be used. By setting the degree of the spring characteristic, the optimum capacity characteristic of the fluid machine can be obtained.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.
The displacement control device of the present invention is applied to a general variable displacement pump and a variable displacement fluid machine of a motor. In this embodiment, a variable displacement pump will be described as an example. However, the present invention is not limited to this, and can be applied to, for example, a variable displacement motor. Since this motor has the same structure as that of the variable displacement pump and only the operation thereof is reversed, the displacement control device for the variable displacement pump will be described in detail in the following embodiments.
[0025]
FIG. 1 is a schematic longitudinal sectional view schematically showing an example of a capacity control device of a variable displacement pump which is a typical embodiment of the present invention, and FIG. 2 is an explanatory diagram schematically showing the capacity control device. is there.
[0026]
In these drawings, reference numeral 1 denotes a displacement control device of a swash plate type piston pump 2 showing an example of a variable displacement pump. As shown in FIG. 2, a shaft (not shown) is rotatably supported inside a housing (not shown) of the pump 2 of the present embodiment, and a cylinder block 3 is rotatably provided with the shaft. Yes. A plurality of cylinder chambers 3a are provided concentrically on the cylinder block 3, and a piston 4 is slidably disposed in the cylinder chamber 3a in the same direction as the axial direction of the shaft.
[0027]
A swash plate 5 that slidably supports a sliding contact surface of a shoe 4a provided on the head of the piston 4 is provided inside the housing so that an inclination angle with respect to the shaft can be adjusted. When the cylinder block 3 rotates together with the shaft, the piston 4 is reciprocated into the cylinder chamber 3a in accordance with the inclination angle of the swash plate 5 to perform suction and discharge pumping operations.
[0028]
Since the swash plate type piston pump 2 configured as described above has a well-known structure that has been widely known in the past, the detailed description thereof is omitted here, and the structure of the capacity control device 1 that forms the feature of the present invention. Will be described in detail below.
[0029]
As shown in FIG. 2, the swash plate 5 is connected and fixed to a servo piston 6 that adjusts an inclination angle. The large-diameter pressure receiving chamber 6 a of the servo piston 6 is connected to the discharge passage 2 a of the pump 2 through the control valve 7, and communicates and is cut off by the control valve 7. The discharge passage 2a communicates with the small diameter pressure receiving chamber 6b of the servo piston 6. The control valve 7 is moved to the communication position by the pump discharge pressure oil, and is moved to the drain position by the urging force of the spring 8.
[0030]
When the servo piston 6 moves toward the small diameter pressure receiving chamber 6b, the rocker cam 9 provided on the servo piston 6 swings the lever 10 in a direction in which the set load of the spring 8 increases. When the servo piston 6 moves toward the large-diameter pressure receiving chamber 6a, the rocker cam 9 swings the lever 10 in the direction in which the set load of the spring 8 is small.
[0031]
In the state shown in FIG. 2, the large-diameter pressure receiving chamber 6 a communicates with the tank through the control valve 7. The discharge pressure of the pump 2 acts on the small diameter pressure receiving chamber 6b, and the servo piston 6 stops in the direction of increasing the pump discharge amount, and the inclination angle of the swash plate 5 is increased. When the load pressure of the actuator 11 increases and the discharge pressure of the pump 2 rises, the control valve 7 is pushed toward the communication position, and the pressure oil output from the control valve 7 via the discharge path 2a It is supplied into the large-diameter pressure receiving chamber 6a. The servo piston 6 moves toward the small diameter pressure receiving chamber 6b, and the inclination angle of the swash plate 5 becomes small due to the pressure receiving area difference between the large diameter pressure receiving chamber 6a and the small diameter pressure receiving chamber 6b, and the pump discharge amount becomes small.
[0032]
The lever 10 swings with the movement of the servo piston 6, and the set load of the spring 8 increases and pushes the control valve 7 toward the drain position. The large diameter pressure receiving chamber 6a side communicates with the tank, the set load of the spring 8 is reduced, and the servo piston 6 is pushed by the discharge pressure and the spring pressure in the small diameter pressure receiving chamber 6b to incline the swash plate 5. The angle increases and the pump discharge rate increases. By repeating this operation, the inclination angle of the swash plate 5 is controlled so that the product (horsepower) of the pump discharge amount and the pump discharge pressure is constant.
[0033]
Next, a specific structure of the capacity control apparatus 1 according to the present embodiment will be described.
As shown in FIG. 1, a servo piston 6 is arranged near the end of the pump body 20, and a rocker cam 9 that moves in a cavity 20 a formed in the pump body 20 stands on the servo piston 6. It is installed. A case body 12 of the control valve 7 is mounted on the upper surface of the pump body 20, and a cavity 12 a is formed in the case body 12 so as to face the cavity 20 a of the pump body 20. A single lever 10 is disposed in the hollow portion 12 a so as to be swingable in the same direction as the operating direction of the servo piston 6, and the lower end portion of the lever 10 is placed in the hollow portion 20 a of the pump body 20. It protrudes.
[0034]
The control valve 7 is arranged in parallel with the operating direction of the servo piston 6. The control valve 7 has a spool 7a that is switched between a communication position and a drain position by pump discharge pressure oil, and a stepped piston 7b that is disposed on the operating axis of the spool 7a. A spring support portion 7d having a disk-shaped spring receiver 7c extends from the tip of the spool 7a. The spring 8 is formed of a compression coil spring, and a spring support portion 7d of the spool 7a is fitted into the spring 8, and the base end of the spring 8 is supported by a spring receiver 7c of the spring support portion 7d. A pressing body 13 having a cylindrical shape with one end opened is fitted into a part of the spring 8.
[0035]
By providing this configuration, the space inside the spring is effectively used, and the expansion and contraction of the spring 8 can be performed smoothly, and the spring characteristics are effectively exhibited so that the control valve 7 and the lever 10 etc. can be accurately Operate. Since the spool 7a and the lever 10 are in direct contact with each other without interposing a casing between the spool 7a and the lever 10 as in the prior art, the length of the capacity control device 1 in the operation axis direction is shortened. Can do.
[0036]
The spring 8 may be a compression coil spring having a different spring constant, for example. In this case, for example, coil springs arranged in multiple stages, or an illegal pitch coil spring having a constant coil diameter or wire diameter and changing pitch, or a cone or barrel having a constant wire diameter and changing coil diameter, etc. A linear spring can be used. Optimum pump displacement characteristics can be obtained by setting the degree of spring characteristics. The pressing surface of the pressing body 13 may be a flat surface or a curved surface. In the present embodiment, the pressing surface has an arcuate curved surface bulging outward, and an optimum pump capacity characteristic can be obtained by setting the curvature of the curved surface.
[0037]
The lever 10 is substantially The An elongated plate member having a letter shape and including both the servo piston 6 and the operation axis of the control valve 7 Vertical It is arranged on a plane. The upper end of the main body 10a of the lever 10 has a swing shaft 10b, and the lower end of the lever 10 is on the same plane as the main body 10a and has a bent portion 10c bent at a predetermined angle. ing. The bent portion 10 c is arranged with the bending direction toward the control valve 7.
[0038]
The swing shaft 10b is located above the set position of the control valve 7, and supports the upper end of the lever in the hollow portion 12a of the case body 12 so as to be rotatable. According to this embodiment, a partial end surface of the bent portion 10c on the opposite side to the bending direction of the lever 10 is in contact with the ball 14 as the first receiving surface, and is on the opposite side to the first receiving surface. A partial end surface of the main body 10a is in contact with the pressing body 13 as a second receiving surface.
[0039]
According to a conventional method, for example, the lever 10 can be provided with a position adjusting function so as to be disposed at a position deviated from the center of the shaft hole of the case body 12. In this case, by changing the swing center of the lever 10, the mounting error of the spring force of the spring 8, each component such as the lever 10 and their assembly errors can be adjusted, and the initial setting of the lever 10 The pump capacity characteristic can be corrected by setting the position and the spring force of the spring 8.
[0040]
A concave spherical surface for fitting the ball 14 is formed at the tip of the rocker cam 9 that transmits the movement of the servo piston 6 to the lever 10. The ball 14 is rotatably supported by the rocker cam 9. In the present embodiment, the ball 14 is disposed on the rocker cam 9, but may be provided on the lever 10. Since the servo piston 6 and the lever 10 are brought into contact with each other via the ball 14 and the displacement of the servo piston 6 can be transmitted to the lever 10 by the ball 14, abnormal wear, friction, scratches, etc. are reduced. Durability can be improved.
[0041]
According to this embodiment, the control valve 7 is arranged in parallel with the operation direction of the servo piston 6, and the lever 10 is arranged on the same plane including both the servo piston 6 and the operation axis of the control valve 7. The servo piston 6 and the control valve 7 are interlocked with each other by swinging the lever 10 on the same plane.
[0042]
By providing this configuration, the lever 10 does not interfere with the spool 7a, the spring 8 and the like of the control valve 7, so that the operation between the spool 7a and the servo piston 6 can be smoothly performed by the lever 10 and It is possible to transmit accurately, the lateral width of the case body 12 of the control valve 7 can be shortened, the capacity control device 1 can be reduced in size, and the pump as a whole can also be reduced in size. Further, the structure can be simplified without using two levers as in the prior art and without increasing the number of parts. For this reason, it is possible to prevent an increase in the number of assembling steps and the complexity of the mounting adjustment work between the components.
[0043]
Next, the operation of the capacity control apparatus 1 according to the present embodiment configured as described above will be described.
When the control valve 7 is switched from the drain position shown in FIG. 2 to the communication position, the spool 7 a of the control valve 7 compresses the spring 8 and presses the main body 10 a of the lever 10 via the pressing body 13. To do. The pressure oil output from the control valve 7 through the discharge passage 2a is supplied to the large-diameter pressure receiving chamber 6a. Due to the pressure receiving area difference between the pressure receiving chambers 6a and 6b of the servo piston 6, the inclination angle of the swash plate 5 increases and the pump discharge amount increases.
[0044]
The rocker cam 9 moves together with the servo piston 6 toward the small diameter pressure receiving chamber 6b. Through the ball 14, the rocker cam 9 presses the bent portion 10c of the lever 10 toward the small-diameter pressure receiving chamber 6b. The set load of the spring 8 increases through the lever 10, the spool 7a moves to the drain position, and the large-diameter pressure receiving chamber 6a communicates with the tank.
[0045]
When the large diameter pressure receiving chamber 6a approaches the drain pressure, the set load of the spring 8 is reduced via the lever 10, and the rocker cam 9 is moved to the servo piston 6 by the discharge pressure and the spring pressure in the small diameter pressure receiving chamber 6b. Together with the large-diameter pressure receiving chamber 6a. The inclination angle of the swash plate 5 is reduced, and the pump discharge amount is reduced. By repeating this operation, the capacity is controlled so that the horsepower becomes constant.
[0046]
3 and 4 show a modification of the capacity control apparatus 1 according to the present embodiment. FIG. 3 schematically shows another structural example of the capacity control device 1. FIG. 4 schematically shows the same capacity control apparatus 1.
[0047]
In the above embodiment, the swing shaft 10 b is provided at the upper end portion of the lever 10 and is supported above the set position of the control valve 7 so as to be swingable in the hollow portion 12 a of the case body 12. In this modification, a swing shaft 10b is provided at an intermediate portion of the lever 10, and is supported in a hollow portion 12a between the control valve 7 and the rocker cam 9 so as to be swingable. In these drawings, substantially the same members as those in the above embodiment are given the same member names and symbols. Therefore, the detailed description regarding these members is omitted.
[0048]
In these drawings, the lever 10 is formed of an elongated plate member having a substantially rectangular shape bent on the same plane. The bent portion 10c of the lever 10 is on the same plane as the main body 10a and is bent at a predetermined angle, and is disposed at the substantially central portion of the pump main body 20.
[0049]
The large-diameter pressure receiving chamber 6a of the servo piston 6 is disposed on the control valve 7 side, and the installation direction is different from that of the servo piston 6 of the above embodiment. The servo piston 6 is provided with a rocker cam 9 having a tip cam surface that forms an inclined surface that gradually increases in the installation direction of the control valve 7. As in the above embodiment, when the servo piston 6 moves toward the small-diameter pressure receiving chamber 6b, the rocker cam 9 swings the lever 10 in the direction in which the set load of the spring 8 increases, and the servo piston 6 When moving to the large-diameter pressure receiving chamber 6a side, the rocker cam 9 swings the lever 10 in the direction in which the set load of the spring 8 is small.
[0050]
In this modification, the lever 10 is placed on the lower side of the control valve 7 with the bent portion 10c of the lever 10 having the swing shaft 10b in the middle portion facing the substantially central portion of the pump body 20. However, the present invention is not limited to this. For example, depending on the setting position of the swash plate 5, the setting position of the control valve 7, the structure of the rocker cam 9, and the lever 10 What is necessary is just to set a setting angle, a direction, etc. suitably. Even if the servo piston 6 is arranged on the end side of the pump body 20, the installation position of the control valve 7 and the spring 8 is not changed, or the design of the existing pump body 20 is not required to be changed. It can be arranged within a set size range corresponding to the size of 20. In addition, the capacity control apparatus 1 having an optimal capacity characteristic with a simple structure and a constant horsepower can be obtained without increasing the number of parts.
[0051]
Although the swash plate type pump motor is described in the embodiments, the present invention can be similarly applied to a swash shaft type pump motor.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view schematically showing an example of a displacement control device of a variable displacement pump that is a representative embodiment of the present invention.
FIG. 2 is an explanatory diagram schematically showing the same capacity control apparatus.
FIG. 3 is a schematic longitudinal sectional view schematically showing another structure example of the capacity control device.
FIG. 4 is an explanatory diagram schematically showing another structure example of the same capacity control device.
[Explanation of symbols]
1 Capacity controller
2 Swash plate type piston pump
2a Discharge path
3 Cylinder block
3a Cylinder chamber
4 Piston
4a shoe
5 Swash plate
6 Servo piston
6a Large diameter pressure receiving chamber
6b Small diameter pressure receiving chamber
7 Control valve
7a spool
7b Stepped piston
7c Spring holder
7d Spring support
8 Spring
9 Rockercam
10 Lever
10a body
10b Oscillating shaft
10c bent part
11 Actuator
12 Case body
12a, 20a Cavity
13 Pressing body
14 balls
20 Pump body

Claims (3)

A displacement control device for a variable displacement fluid machine that controls the displacement according to the amount of movement of the servo piston,
A control valve for controlling the movement amount of the servo piston;
The control valve is arranged in parallel with the operation direction of the servo piston, and has a spool that is switched to a communication position and a drain position by pump discharge pressure oil, and a spring that is directly provided at the tip of the spool. ,
The servo piston has a lock cam that moves in a cavity formed in a body of the variable displacement fluid machine,
It is on the same vertical plane including the operation axis of the servo piston and the control valve, has a swing shaft at the upper end, and swings in the same direction as the operation direction of the servo piston around the swing shaft. It has a single lever made of a plate member, and the lower end portion of the lever has a substantially square shape with a bent portion on the plane and bent toward the control valve,
A part of the end face of the bent part opposite to the bending direction contacts the lock cam, and a part of the end part of the bent part opposite to the contact face contacts the tip of the spring of the control valve. becomes, variable displacement fluid machine of the displacement control device, characterized in that. The capacity control device according to claim 1, wherein the lever and the servo piston are in contact with each other via a ball. 2. The spring comprises a compression spring, and a spring support portion extended at the tip of the spool is fitted into the spring, and the spring support portion supports the base end of the spring. The capacity control device described.

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