JP2915604B2 - Variable displacement piston pump motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston pump motor, and more particularly to a variable displacement piston pump motor having a displacement control mechanism for variably controlling the displacement of the piston pump motor.

[0002]

2. Description of the Related Art Conventionally, as one of hydraulic rotary motors frequently used in a hydraulic servo mechanism, there is, for example, a swash plate type hydraulic piston pump motor. This piston pump motor changes a tilt angle of a swash plate to change a piston stroke. There is one that controls the power and variably controls the capacity.

In this type of variable displacement piston pump motor, fine control of output (rotational speed and torque) is required in accordance with the control target and load fluctuation. For this reason, as a capacity control mechanism responsible for the control, a servo valve that slightly changes the valve opening according to the load pressure, a variable mechanism that changes the tilt angle of the swash plate by receiving the servo oil pressure to change the capacity, And a feedback mechanism for adjusting the interlocking relationship between the variable mechanism and the servo valve.

[0004]

However, in such a conventional variable displacement piston pump motor, since the feedback mechanism has a complicated structure, the variable displacement piston pump motor as a whole is complicated. It was large and the cost was high.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a simple and inexpensive variable displacement piston pump motor which realizes a simple displacement control mechanism having a structure in which a change in the inclination of a swash plate is directly fed back to a servo valve. And

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a system for holding a plurality of pistons so as to extend and retract.
Cylinder and the cylinder
The swash plate that rotates the block, the cylinder block and the swash plate
Port block containing a plate and forming a pair of pressure oil supply / discharge passages
Variably controls the angle of the swash plate and the housing provided with the
Variable displacement piston pump having a displacement control mechanism
In the pump motor, the capacity control mechanism is provided from a supply source.
On the back side of the swash plate to increase the inclination of the swash plate by hydraulic pressure
Variable piston provided and port of the housing
The spool provided in the block and responding to the pilot pressure
The spool until the pilot pressure reaches a predetermined value.
Hydraulic pressure to be sent to the variable piston
Release, and the pilot pressure is equal to or higher than the predetermined value.
The spool can be moved from the predetermined position to one side
Servo for supplying oil pressure from the supply source to the changing piston
Between the valve and the variable piston and the spool of the servo valve.
Having a biasing member that is present, the swash plate or the variable piston
According to the displacement, the biasing member causes the servo valve to
Feeder for urging the other side toward the predetermined position.
Back means, wherein the biasing member is
Provided in the housing for urging the spool toward the other side.
Interposed between the spring and the variable piston
Characterized in that it is constituted by a rod member that is present, preferably on the back side of the swash plate,
Receiving hydraulic pressure from a supply source, the swash plate is tilted in a decreasing direction.
To the variable piston by the servo valve.
Capability to reduce the tilt angle of the swash plate when hydraulic pressure is released
A piston for reducing the amount is provided .

[0007]

According to the present invention, feedback means is provided with an urging member interposed between the variable piston and the servo valve, and a change in the inclination of the swash plate is mechanically fed back to the servo valve by the feedback means. Therefore,
A small capacity control mechanism having a simple structure is provided in the housing.

[0008] Also, a pimple for reducing the capacity is provided on the back side of the swash plate.
To adjust the inclination of the swash plate in the direction of decreasing
When the hydraulic pressure to the stone is released, the piston
If the inclination of the swash plate is reduced by
The pressure receiving area can be large while using the hydraulic pressure from the supply source.
Just switch the working piston working pressure to high or low
Control becomes possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 and 2 are views showing one embodiment of a variable displacement piston pump motor according to the present invention, showing an example in which the present invention is applied to a hydraulic motor. First, the configuration will be described.

In FIG. 1, reference numeral 11 denotes a housing, and the housing 11 is provided with a port block portion 11a. A pair of pressure oil supply / discharge passages 12 and 13 are formed in the port block portion 11a, and the pair of pressure oil supply / discharge passages 12 and 13 respectively respond to a control valve (not shown), for example, an operation input. The control valve is connected to a three-position switching valve. When the control valve is in the neutral position, the control valve connects the hydraulic pump and the tank (both not shown) and the two pressure oil supply / discharge passages 12 and 13 to each other. In the switching position, one pressure oil supply / discharge passage
12 or 13 to the hydraulic pump and the other hydraulic oil supply / discharge passage 13 or 12
To the tank.

A plurality of cylinders are provided in the housing 11.
A cylinder block 15 having a cylinder 14 is housed therein. The cylinder block 15 is spline-coupled to a shaft 16 as a motor output shaft, and the shaft 16 is supported by the housing 11 via bearings 17 and 18. Pistons 19 are slidably housed in the plurality of cylinders 14 of the cylinder block 15, respectively, and the pistons 19 sequentially expand and contract, and the shoe plate 21 is in sliding contact with the non-rotating swash plate 22, and the cylinder block 15 and the shaft 16 rotate. In order to sequentially stroke the plurality of pistons 19, a known timing plate 23 is provided between the port block portion 11a of the housing 11 and the cylinder block 15, and the timing plate 23 During rotation, pressure oil is supplied from one pressure oil supply / discharge passage 12 or 13 to a cylinder 14 in a predetermined rotation section, and oil is discharged from the cylinder 14 in another predetermined section to the other pressure oil supply / discharge passage 13 or 12. .

The swash plate 22 and the swash plate 22 are slidably housed in hydraulic chambers 33 and 34 so as to be located on opposite sides of the shaft 16.
Are a pair of large and small variable pistons facing the back surface of the. When the variable pistons 31 and 32 receive the same hydraulic pressure, the piston 31 having a large pressure receiving area overcomes the thrust of the piston 32 having a small pressure receiving area to increase the inclination angle of the swash plate 22. The hydraulic chamber 33 is provided in the housing 11
The hydraulic oil from the servo valve 40 is introduced through a servo pressure passage 35 formed in the
a (for example, a passage communicating with a high-pressure passage 36 described later) to introduce high-pressure oil. Therefore, when the pressure only in the hydraulic chamber 33 drops below the predetermined pressure , the capacity reduction pin
The variable piston 32 , which is a ston, presses the back surface of the swash plate 22 to reduce the inclination angle of the swash plate 22.

As shown in FIG. 2, the servo valve 40 includes a spool 41, a sleeve 42 fixed to the port block portion 11a of the housing 11, and slidably accommodates the spool 41, and abutable with the spool 41. Spool via retainer member 44
Spring 43 for urging 41 to the left in the figure, and retainer member
And a retainer member 45 for holding the spring 43 between the member 44 and the member 44. These members 41 to 45 are coaxially arranged. When the load pressure (pressure oil on the high pressure side of the pressure oil supply / discharge passages 12 and 13) supplied to the pilot pressure passage 37 is equal to or higher than a predetermined pressure, the servo valve 40 uses the spring pressure by the load pressure (pilot pressure). By moving the spool 41 to the right in the drawing against the repulsive force of the above, the load pressure from the high pressure passage 36 or the high pressure from another hydraulic source can be supplied to the servo pressure passage 35. Also,
When the load pressure supplied to the pilot pressure passage 37 is equal to or less than a predetermined pressure, the servo valve 40 moves the spool 41 to the left side in the drawing by the repulsive force of the spring 43, and cuts off the communication between the high pressure passage 36 and the servo pressure passage 35. At the same time, the pressure in the servo pressure passage 35 can be released. That is, the servo valve 40 controls the pressure oil sent to the variable piston 31.

More specifically, as shown in FIG.
The 40 spool 41 is connected to the land 41 on the pilot pressure passage 37 side.
b is smaller in diameter than the central land 41a, and the central land 41a
And the land 41c on the servo pressure passage 35 side have the same diameter, and the difference between the pressure receiving areas of the lands 41a and 41b that define the hydraulic chamber 39 among the annular hydraulic chambers 38 and 39 that are always in communication with the passages 36 and 37. As a result, a rightward thrust in the figure according to the hydraulic pressure (pilot pressure) in the hydraulic chamber 39 is generated. Further, the spring 43 moves the spool 41 via the retainer member 44 to a predetermined position (position shown).
Energize. Therefore, when the load pressure in the pilot pressure passage 37 increases, the spool 41 first moves to the right in the drawing,
The annular hydraulic chamber 38 communicates with the port 40a on the servo pressure passage 35 side at a predetermined load pressure. A drain passage 41d is formed in the land 41c of the spool 41. When the load pressure falls below a predetermined pressure, the port 40a and the annular hydraulic chamber 38 are shut off. 40a communicates with the drain passage 41d.

The retainer member 44 is urged by a repulsive force of the spring 43 to one end side which abuts the spool 41 in the axial direction, and is urged by the flange portion 44a at one end to the port block portion 11a. It is supposed to be.
The retainer member 45 is connected to one end of a rod member 46 extending parallel to the shaft 16, and the other end of the rod member 46 is rotated by the swash plate 22 via a rotation member 47 and a connection pin 48 ( (Swinging). Further, the curved surface portion 47a of the rotating member 47 abuts on the variable piston 31. Then, these coaxially arranged spring 43, retainer member 45, rod member 46, rotating member 47 and connecting pin 48 are
The feedback means 49 is located between the variable piston 31 and the servo valve 40.
The spring 49 and the lock 43 serve as urging members for displacing the swash plate 22 or the variable piston 31 on the axis of the spool 41.
This is fed back to the servo valve 40 via the sliding member 46 .

A multi-plate friction brake mechanism 50 is provided between the outer peripheral portion of the cylinder block 15 and the housing 11. This brake mechanism 50
A plurality of first friction plates 51 spline-coupled to an outer peripheral portion of
A plurality of second friction plates 52 attached to the inner wall of the housing 11 so as to be movable only in the thickness direction by spline coupling over a part or the entire periphery, and a brake piston 53 slidably provided in the housing 11, The brake piston 53 is urged toward the first and second friction plates 51 and 52 to clamp the friction plates 51 and 52 between the stopper 56 and the stopper 56 fixed to the housing 11,
It has a pair of disc springs 54 and 55 for generating a brake fastening force, an oil chamber 57 defined between the housing 11 and the brake piston 53, and an oil path 58 for supplying and discharging a release hydraulic pressure to and from the oil chamber 57. ing. The housing 11, the second friction plate 52, the brake piston 53, and the stopper 56 are provided with holes through which the rod member 46 passes.

Next, the operation will be described. In this embodiment having such a configuration, the spool 41 is moved by the repulsive force of the spring 43 until the load pressure supplied to the pilot pressure passage 37 reaches a predetermined pressure (while the motor load is small). The servo pressure passage 35 is in communication with the drain passage 41d during this time.
In this state, the swash plate 22 receives the pressing force of the variable piston 32 having received the load pressure from the high-pressure passage 36, and rotates in the clockwise direction in the figure to reduce the tilt angle. Therefore, at this time, high-speed driving becomes possible.

On the other hand, when the load pressure supplied to the pilot pressure passage 37 reaches a predetermined pressure, the spool 41 moves to the right in the drawing against the repulsive force of the spring 43 and moves to the annular hydraulic chamber 38 and the port.
Connect 40a. As a result, the high pressure in the high-pressure hydraulic chamber 38 is supplied to the hydraulic chamber 33 through the servo pressure passage 35, and the variable piston 31 receives this servo pressure. In this state, since the hydraulic pressure from the same hydraulic pressure source is guided to the hydraulic chambers 33 and 34, the piston 31 having a large pressure receiving area overcomes the pressing force of the piston 32 having a small pressure receiving area to move the swash plate 22 in the drawing. The swash plate 22 is rotated counterclockwise to increase the tilt angle.
Therefore, at this time, it is possible to drive at a low speed with a large output torque.

When the inclination angle of the swash plate 22 changes, the feedback means 49 changes the inclination angle of the swash plate 22 (ie, the displacement of the variable piston 31) via the spring 43 (as a change in the repulsive force of the spring 43). ) Spool 41 of servo valve 40
Feedback to Therefore, when the load pressure is equal to or higher than the predetermined pressure, the port 40a is automatically adjusted so as to shut off the annular passage 38 and the drain passage 41d, and the inclination angle of the swash plate 22 corresponding to the load pressure is maintained.

As described above, in the present embodiment, the change in the inclination angle of the swash plate 22 is directly applied to the servo valve 40 by the feedback means 49 located on the axis between the servo valve 40 and the variable piston 31. Since the valve characteristics of the servo valve 40 are adjusted by providing feedback, there is no need to provide a large and complicated feedback mechanism between the variable tilt angle mechanism and the servo valve as in the past, and the configuration is simple and compact. Can be easily provided in the housing 11, and a small and inexpensive variable displacement piston pump motor can be provided. Further, the feedback means 49 is
The rod member 46 is made to respond to the inclination or the reciprocation of the variable piston 31 and the displacement of the rod member 46 is fed back via the spring 43, so that these members 43 and 46 are arranged coaxially. A simpler control mechanism can be realized. Further, in the present embodiment, although the friction brake mechanism 50 (friction element) is provided around the cylinder block 15, a rod member is attached to the second friction plate 52 and the brake piston 53 which are fixed sides thereof. The desired capacity control can be performed without any support for the operation of the brake mechanism 50 only by passing the 46 through.

[0021]

According to the present invention, the displacement of the swash plate or the variable piston is fed back to the servo valve by the feedback means located between the variable piston and the servo valve. A small displacement control mechanism can be easily provided in the housing, and a small and inexpensive variable displacement piston pump motor can be provided.

Also, the displacement of the swash plate or the variable piston is added .
Since the feedback means is configured to feed back to the servo valve via the biasing member , a simpler control mechanism can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of a variable displacement piston pump motor according to the present invention.

FIG. 2 is a partially enlarged sectional view showing the vicinity of a servo valve according to one embodiment.

[Explanation of symbols]

11 Housing 12, 13 Pressure oil supply / discharge passage 15 Cylinder block 19 Piston 22 Swash plate 31 Variable piston 32 Variable piston (capacity reducing piston) 35 Servo pressure passage 36 High pressure passage 37 Pilot pressure passage 38, 39 Hydraulic chamber 40 Servo Valve 41 Spool (valve element) 43 Spring (biasing member) 46 Rod member (biasing member) 49 Foot back means

Claims (2)

(57) [Claims] 1. A plurality of pistons are held so as to extend and retract.
The cylinder block and the piston
Swash plate for rotating the cylinder block, cylinder block and
Port that houses the swash plate and forms a pair of pressure oil supply and discharge passages
Variable inclination of housing with block and swash plate
Variable displacement piston having a displacement control mechanism for controlling
In the pump motor, the displacement control mechanism may be configured to increase a tilt angle of the swash plate by hydraulic pressure from a supply source.
A variable piston provided on the back side of the plate, and a pilot provided on a port block of the housing.
With a spool that responds to pressure, the pilot pressure is
Position the spool until it reaches
Release the hydraulic pressure sent to the
The spool is in the predetermined position when the pressure is higher than the predetermined value.
From the supply source to the variable piston
Interposed between the servo valve that supplies hydraulic pressure, and the variable piston and the spool of the servo valve
It has an urging member, and it
Accordingly, the spool of the servo valve is moved forward by the biasing member.
Feedback to bias the other side toward the predetermined position
Means, wherein the biasing member is provided in the housing, and
A spring for biasing the pool to the other side;
And the rod member interposed between the variable piston
Variable displacement piston pump motor, characterized in that constructed me. 2. An oil from the supply source is provided on a back side of the swash plate.
Receiving the pressure to urge the swash plate in the direction of decreasing the inclination angle,
The hydraulic pressure to the variable piston is released by the servo valve.
Volume reduction fixie that reduces the inclination angle of the swash plate when
2. The variable displacement piston pump motor according to claim 1, further comprising: