JPH0528391Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a variable displacement axial piston pump whose discharge amount is varied by a swash plate.

(Prior art) Conventionally, as an axial piston pump,
As shown in the figure, a cylinder block c rotated by a drive shaft b is provided in a pump housing a, and the strokes of a plurality of pistons d provided in the cylinder block c so as to be freely retractable are fixed in the housing a. controlled by a swash plate e provided in the state,
A constant discharge type is known in which a fixed amount is discharged from the cylinder block c.

Also as an axial piston pump, the second
As seen in the figures and FIG. 3, a swash plate e is supported in a pump housing a so as to be tiltable by a support shaft f protruding in the circumferential direction, and a tilt angle of the swash plate e is supported within the housing a. A small-diameter control cylinder g that acts to increase the tilt angle and a large-diameter control cylinder h that acts to decrease the tilt angle against the small-diameter cylinder g are provided. A variable displacement type is also known in which the tilting angle of the swash plate e is controlled by controlling the introduction of pressure fluid, thereby making the discharge amount from the cylinder block c variable. In FIG. 2, i is a screw that adjusts the maximum discharge amount, and j is a pilot valve that controls the introduction of pressure fluid into the large diameter cylinder h.

(Problem to be solved by the invention) Fixed displacement pumps can generally be constructed in a small size and are often used, for example, as hydraulic pumps for vehicles with limited installation space, but their discharge volume is variable. Since this is not possible, it is not possible to use the energy saving method of reducing the driving force of the pump. On the other hand, the variable displacement type has the advantage of reducing the discharge amount and reducing the pump power, allowing for energy-saving operation. However, even in the case of a variable displacement type pump, which is currently the most compact configuration shown in Figure 2, compared to a fixed displacement type, there are large and small control cylinders g, h, etc. provided on the sides of the cylinder block c. Since the support shaft f of the swash plate e protrudes in the circumferential direction as shown in the third figure, the mechanism becomes larger and its weight approximately doubles, making it unsuitable for use as an automobile part that is required to be smaller and lighter.

The object of the present invention is to provide a variable displacement axial piston pump that meets the requirements for smaller size and lighter weight.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a swash plate in the pump housing that controls the strokes of a plurality of pistons that come and go from a cylinder block rotated by a drive shaft. In the case where the support shaft of the swash plate is provided on the inner wall of the pump housing in the direction of the drive shaft, the swash plate is rotated by the force of each piston acting on the front surface of the swash plate. A control piston is provided behind the swash plate to support a position where a rotational force is generated to increase the tilt angle, and a control piston is provided behind the swash plate to support the rotational force of the swash plate.

(Function) When the cylinder block rotates due to the rotation of the drive shaft, the piston provided in the cylinder block so as to be able to come out and go back and forth reciprocates between the swash plate surface and discharges pressurized fluid from the cylinder block, which is different from the conventional variable displacement type. It is similar to the axial piston pump of 1999, and the discharge amount can be increased or decreased by changing the tilt angle of the swash plate, but the pivot of the swash plate is
It is provided on the inner wall of the pump housing in the direction of the drive shaft and supports the position where the rotational force that increases the tilting angle of the swash plate is generated by the force from each piston acting on the swash plate. There is no means for tilting the swash plate to the side of the swash plate and to the side of the cylinder block, and the diameter of the pump housing becomes smaller. Further, the swash plate is tilted by controlling the introduction of pressure fluid to a control piston that supports the rotational force, and the control piston may be provided to support the rotational force from the back side of the swashplate. Since the back surface supports the point closest to the pump housing, the swash plate can be tilted with a small control piston without increasing the length of the pump housing.

(Embodiment) An embodiment of the present invention will be described based on FIG. 4 of the drawings. a pump housing consisting of an end cover 1c attached to cover the end of the front cover 1a; a drive shaft 2 inserted through the front cover 1b;
3 is a cylindrical cylinder block that is integrally attached to the drive shaft 2 and rotates; 4 is a plurality of cylinder bores formed in the cylinder block 3 in parallel with the drive shaft 2; The drive shaft 2 is arranged in an arc shape within the circular cross section of the block 3 with the drive shaft 2 as the center. 6 is the cylinder bore 4
A piston 8 whose tip end is inserted into the pump housing 1 and whose spherical head at the rear end is attached to an annular slide plate 7 is rotatable in the axial direction of the drive shaft 2 by a support shaft 9 inside the pump housing 1. With the swash plate provided,
A slide plate 7 is provided in slidable contact with the front surface 8a of the swash plate 8.

The above configuration is the same as that of a conventional axial piston pump, and changing the tilt angle of the swash plate 8 changes the stroke of the piston 6 and similarly increases or decreases the pump discharge amount. In this case, the support shaft 9 of the swash plate 8 is connected to the inner wall of the pump housing 1 in the direction of the drive shaft 2, and also to the front surface 8 of the swash plate 8.
A is provided so as to support a position that generates a rotational force in a direction in which the tilting angle of the swash plate 8 is increased by the force of each piston 6 acting on the swash plate 8, and the rotation force is supported behind the swash plate 8. control piston 10
The control piston 10
The tilting angle of the swash plate 8 can be varied by controlling the pressure fluid introduced into the swash plate 8 and controlling the moving distance thereof.

Specifically, the support shaft 9 is connected to the pump housing 1
front cover 1b located in the direction of the drive shaft 2 of
The swash plate 8 is constructed by attaching two semicircular cross-section shaft members 9b, 9b having a pin 9a to the inner surface of the swash plate 8, as shown in FIG.
Then, as shown in FIG. 6, the swash plate 8 is
A rotational force is generated in the direction of increasing the tilt angle α. Further, a control piston 10 is buried in a position where the back surface 8b of the swash plate 8 approaches the front cover 1b so as to be retractable and retractable, and its retracting and retracting operations are controlled by controlling the pressure fluid introduced through the inlet 11. I did it like that.

To further explain this while comparing it with the conventional one, the conventional one, as seen in Fig. 3, has the following characteristics:
The support shaft f of the swash plate e is provided on the axis k passing through the center of the swash plate e, and the point on which the total force F of each piston d of the cylinder block c acts is the front surface of the swash plate e that is inclined toward the cylinder block c side. Therefore, the swash plate e generates a rotational force that makes its tilt angle δ 0°, and this rotational force is applied to the large and small control cylinders on the sides of the cylinder block c. It is supported in g and h.

In contrast, in the present invention, the support shaft 9 is located on the inner wall of the front cover 1b, and at a position where the rotational force that increases the tilting angle α by the total force F of the pistons 6 is generated on the swash plate 8. Since the rotational force is supported by the control piston 10 behind the swash plate 8, there is no device on the side of the cylinder block 3 for adjusting the tilt angle of the swash plate 8. Therefore, the pump housing 1 can be brought closer to the cylinder block 3, making the pump housing 1 smaller and lighter in weight. Also, since the distance between the support shaft 9 of the swash plate 8 and the point of action of the control piston 10 can be increased, the tilting operation can be made easier. A small control piston 10
The tilting device can be made lighter because it can be done with

In FIG. 4, reference numeral 12 indicates a discharge port, and 13 indicates a suction port. Incidentally, the support shaft 9 is formed of the shaft members 9b, 9 having the semicircular cross section.
In place of b, two members each having a hemispherical cross section may be used.

(Effect of the invention) As described above, according to the invention, the support shaft of the swash plate is connected to the inner wall of the pump housing in the direction of the drive shaft, and the rotational force that increases the tilt angle of the swash plate is generated by each piston. Since a control piston is provided behind the swash plate to support the rotational force, the swash plate can be tilted by the total force of the small control piston and the piston of the cylinder block. The angle turning device can be simplified and lightened, and since the pump housing can be formed close to the cylinder block, the housing can also be made lighter and smaller, resulting in an overall smaller and lighter axial piston pump, which is suitable for use in vehicles. It has the advantage that it can be particularly conveniently applied to.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional fixed displacement axial piston pump, Fig. 2 is a sectional view of a conventional variable displacement axial piston pump, and Fig. 3 is a simplified perspective view of the main parts of Fig. 2. Figure 4 is a sectional view of the embodiment of the present invention, Figure 5 is a simplified perspective view of the main parts of Figure 4, and Figure 6 is a simplified side view of the main parts of Figure 4. show. 1...Pump housing, 2...Drive shaft, 3...
...Cylinder block, 6...Piston, 8...Swash plate, 8a...Front, 9...Spindle, 10...Control piston.

Claims (1)

[Scope of utility model claims] In a pump housing in which a swash plate that controls the strokes of a plurality of pistons that protrude and retract from a cylinder block rotated by a drive shaft is provided so as to be tiltable by a support shaft, the support shaft of the swash plate is provided on the inner wall of the pump housing in the direction of the drive shaft to support a position where the force of each piston acting on the front surface of the swash plate generates a rotational force that increases the tilting angle of the swash plate; A variable displacement axial piston pump characterized in that a control piston is provided behind the swash plate to support the rotational force of the swash plate.