JPH0649916Y2 - Swash plate type variable displacement piston pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a variable displacement piston pump that controls the stroke of a piston that moves in and out of a cylinder block by a swash plate to increase or decrease the pump displacement.

(Prior Art) Conventionally, as shown in the first drawing, a cylinder block c is attached to a drive shaft b introduced from the outside into a pump case a, and a head of a piston d provided to be retractable in the cylinder block c is Control piston e provided parallel to the piston d
There is known a swash plate type variable displacement piston pump having a structure in which the swash plate h is tilt-controlled by a control cylinder f about an axis g.

(Problems to be Solved by the Invention) In the conventional device, the swash plate h is tilted about the axis g by controlling the supply of the pressure oil to the control cylinder f, and the head of the swash plate h is tilted. Although the stroke of the piston d that is engaged with the pump can be changed to change the pump displacement, the swash plate h for tilting the valve directly contacts the control piston e and the control cylinder f, and the contact is a line contact. Therefore, even if the contact portion of the swash plate h is subjected to an oil bath in the pump case a, an oil film is not easily formed on the contact portion, and metal contact is likely to occur. Therefore, the contact portion tends to wear,
When the wear occurs, a recess is formed in the contact portion, and a lateral load is applied to the control piston e and the control cylinder f, which causes an inconvenience that a malfunction easily occurs. Further, there is a drawback that the maximum tilt angle of the swash plate h increases due to the depression caused by wear.

Further, since the swash plate h slightly vibrates due to the force from the piston d, if the swash plate h and the control piston e and the control cylinder f are in metal contact with each other, noise is likely to occur.

An object of the present invention is to provide a swash plate type variable displacement pump that solves these problems.

(Means for Solving the Problem) In the present invention, a control piston and a control cylinder in which a plurality of pistons are provided in a cylinder block rotated by a drive shaft so as to be retractable and retractable, and a head of the piston is provided in parallel with the piston A swash plate that is tilt-controlled by a swash plate is provided with a substantially hemispherical recess at each contact portion of the swash plate with the control piston and the control cylinder, and a cutting plane is formed in the recess. The above-mentioned object is achieved by fitting the spherical portion of the spherical slipper that it has so that it can swing, and bringing the cutting plane of the slipper into contact with the planar end portions of the control piston and the control cylinder.

(Operation) When the tilt angle of the swash plate is controlled by rotating the drive shaft by an internal combustion engine or the like and supplying pressure oil of appropriate pressure to the control cylinder, the tilt angle is adjusted by the piston that reciprocates in the cylinder block. A proportional amount of pressure oil is extruded from the cylinder block, but spherical slippers each having a concave surface and a cutting plane are fitted at the portions where the swash plate contacts the control piston and the control cylinder, respectively. Therefore, as the tilt angle of the swash plate changes, the slippers oscillate in the recesses, and the cutting planes of the slippers come into contact with the flat end portions of the control piston and the control cylinder in a flat plane. As a result, the surface pressure at the contact portion is reduced and an oil film is formed. As a result, wear of the swash plate is reduced and malfunctions are less likely to occur, and noise is less likely to occur even if the swash plate slightly vibrates due to the oil film cushioning.

(Embodiment) An embodiment of the present invention will be described with reference to FIG. 2 in the drawing. In the figure, reference numeral (1) is a drive shaft introduced from the outside into a pump case (2), and (3) is the drive shaft. A cylinder block that engages with the spline (4) formed in (1), and a reference numeral (5) indicates a piston provided in each of a plurality of bores (6) formed in the cylinder block (3) so as to be retractable.

The spherical head (5a) of the piston (5) has a slide shoe (9) and a ring (10) on a swash plate (8) tiltably supported by a pump case (2) about a shaft (7). Will be mobilized by. (11) and (12) are the piston (5)
When a pressure oil is introduced from a mortgage hydraulic source into the chamber (13) of the control cylinder (12) by a control piston and a control cylinder that are provided in parallel with each other and are shifted by 180 ° around the drive shaft (1), the control is performed. Cylinder (12)
Bends the spring (14) of the control piston (11) to tilt the swash plate (8), and the tilt changes the stroke of the piston (5) protruding and retracting from the cylinder block (3). , Pump capacity changes.

Although this structure is not different from the conventional one, in the present invention, the swash plate (8) is the control piston (11).
And the recesses (17) (1) (1) of the contact portions (15) (16) that come into contact with the flat end portions of the control cylinder (12).
7) is formed, and the spherical parts of the spherical slippers (19) having the cutting planes (18) are fitted into the respective recesses (17). Since the slipper (19) swings freely with respect to the swash plate (8), the respective cutting planes (18) of the slipper (19) come into surface contact with the control piston (11) and the control cylinder (12), respectively. Even if the tilt angle of the plate (8) changes, the surface contact state can be maintained by the swing of the slipper (19). Reference numeral (20) is an oil supply hole for the recess (17) formed in the swash plate (8).

The hydraulic oil is stored in the pump case (2) and is repelled by the rotation of the cylinder block (3) so that the swash plate (8) is in an oil bath state, but the cutting plane (18) of the slipper (19). When the control piston (11) and the control cylinder (12) come into surface contact with each other, the surface pressure becomes lower than in the case of line contact, and the splashed oil easily forms an oil film at the surface contact portion, Since the wear is reduced and the control piston (11) and the control cylinder (12) are less likely to receive a lateral load, malfunction of the swash plate (8) can be prevented.

Further, since the oil film formed on the surface contact portion serves as a cushion, noise due to slight vibration of the swash plate is less likely to occur.

(Effects of the Invention) As described above, according to the present invention, the swash plate of the variable displacement piston pump is connected to the control piston and the control cylinder for controlling the tilting of the swash plate.
Since a spherical portion of a spherical slipper having a cutting plane is fitted into the concave portion having a substantially hemispherical shape so as to be swingable, the contact between the swash plate, the control piston and the control cylinder can be made into a surface contact, and the contact portion An oil film is easily formed on the swash plate, wear of the swash plate and generation of noise are prevented, and the force acting on the control piston and control cylinder is mainly in the axial direction and the lateral load is small, so these operate smoothly. It also has the effect of preventing malfunction of the swash plate.

[Brief description of drawings]

FIG. 1 is a cutaway side view of a conventional example, and FIG. 2 is a cutaway side view of an embodiment of the present invention. (1) …… Drive shaft (3) …… Cylinder block (5) …… Piston, (5a) …… Head (8) …… Swash plate (11) …… Control piston (12) …… Control cylinder ( 15) (16) …… contact part, (17) …… recessed part (18) …… cutting plane, (19) …… slippers

Claims (1)

[Scope of utility model registration request] 1. A swash plate in which a plurality of pistons are provided in a cylinder block rotated by a drive shaft so that the pistons can be retracted and retracted, and a head of the pistons is provided in parallel with the pistons and a tilt is controlled by the control cylinders. The swash plate is provided with a substantially hemispherical concave portion at each contact portion of the swash plate with the control piston and the control cylinder, and a spherical portion of a spherical slipper having a cutting plane is formed in the concave portion. A swash plate type variable displacement piston pump, wherein the swash plate type variable displacement piston pump is fitted so as to be swingable and the cutting plane of the slipper is brought into contact with the plane ends of the control piston and the control cylinder.