JPH0311423Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention involves inserting a piston into the cylinder hole of a cylinder block installed at a predetermined angle of inclination with respect to the drive shaft, and connecting this piston to the drive shaft. This invention relates to a piston of an oblique shaft type axial piston pump/motor in which the piston is reciprocated by rotating a drive shaft.

Prior Art As shown in Japanese Unexamined Patent Publication No. 50-84907, a piston inserted into a cylinder hole of a cylinder block is
having a shape having a spherical surface portion that fits tightly and slides in the cylinder hole and a substantially truncated conical portion having a smaller diameter than the spherical surface portion;
A piston whose approximately truncated conical part contacts the inner circumferential surface of the cylinder hole, allowing the piston to tilt relative to the cylinder hole, and also increases the strength by increasing the contact area between the inner circumferential surface of the cylinder hole and the piston. It has been known.

However, with this structure, a seal ring is provided on the approximately truncated conical part, and this seal ring maintains liquid tightness between the cylinder hole and the piston. The distance to the seal ring becomes long and a large force is applied to the seal ring, causing early damage to the seal ring and liquid leakage.

Purpose of the invention The purpose of the invention is to provide a seal ring that can be tilted relative to the cylinder hole, has increased strength, and also improves durability without applying excessive force to the seal ring.

Structure of the device: A seal ring having a spherical outer circumferential surface approximately equal to the inner diameter of the cylinder hole is attached to one end of the piston body in the longitudinal direction, and both ends of the piston body in the longitudinal direction are tapered to form an integral structure. The piston member is tiltable with respect to the cylinder hole, and is designed to prevent excessive force from acting on the seal ring.

Embodiment FIG. 1 is a sectional view of a diagonal shaft type axial piston pump/motor, in which a cylinder block 2 is installed inside a cylindrical housing 1, and a plurality of cylinder holes 3 are formed in the cylinder block 2 in the circumferential direction. A piston 4 is slidably inserted into the cylinder hole 3 to form a cylinder chamber 3a, and a body 5 is fixed to the housing 1, and a drive shaft is installed in the body 5. 6 is rotatably supported by a bearing 7, and the piston 4 is swingably connected to the drive shaft 6.

A valve plate 9 is interposed between the cylinder block 2 and the end cover 8.

Because of this, by rotating the drive shaft 6, the piston 4 reciprocates and changes the volume inside the cylinder chamber 3a, thereby functioning as a pump, and conversely, by supplying pressure oil to the cylinder chamber 3a, the piston 4 is moved. By reciprocating, the drive shaft 6 rotates and becomes a motor.

At this time, the piston 4 slides along the cylinder hole 3 and also tilts.

As shown in FIG. 2, the piston 4 has an annular groove 11 formed at one end in the longitudinal direction of the piston body 10, and both side portions 12 of the annular groove 11 have a perfect circular shape. , 12 have a tapered shape, the other end 14 in the longitudinal direction has a spherical shape, and a hole 15 is formed in the axis.
This hole 15 is connected to the annular groove 1 by a small hole 16.
The opening communicates with 1.

A seal ring 17 is provided in the annular groove 11.
is fitted, and the outer circumferential surface 1 of the seal ring 17
7a is spherical, and the maximum outer diameter is the cylinder hole 3.
It is made equal to the inner diameter of.

Thus, the piston 4 tilts around the maximum outer diameter portion of the spherical outer circumferential surface 17a of the seal ring 17 as a fulcrum, and the tapered portions 13, 13 contact the inner circumferential surface of the cylinder hole 3, so that the piston 4 is integrally formed. In addition to being able to tilt with respect to the cylinder hole 3, the tapered portions 13, 13 can contact the inner circumferential surface of the cylinder hole 3 to increase the contact area, thereby increasing the strength.

Further, since the seal ring 17 is tilted using the seal ring 17 as a fulcrum, no large unreasonable force is applied to the seal ring 17, and the seal ring 17 is not damaged early, so that durability can be improved.

In addition, the cylinder chamber 3a is made of holes 15 and 16.
Since the high-pressure oil inside is applied to the inner peripheral surface of the seal ring 17 and the seal ring 17 is pressed against the inner peripheral surface of the cylinder hole 3, sealing performance is improved.

Effect of the invention The piston 4 has a spherical outer peripheral surface 1 of the seal ring 17
Since the tapered portion contacts the inner circumferential surface of the cylinder hole 3 by tilting around the maximum outer diameter portion of the piston 7a as a fulcrum, the piston 4 can be integrally tilted relative to the cylinder hole 3, and the tapered portion contacts the inner circumferential surface of the cylinder hole 3. Since the contact area can be increased by contacting the inner circumferential surface of piston 3, not only can the strength be increased, but also piston 4 can
The contact surface pressure between the cylinder hole 3 and the cylinder hole 3 can be lowered, and the distance from the tilting fulcrum to the tapered portion is shortened so that no large bending stress is applied.

Further, since the piston 4 tilts with the seal ring 17 as a fulcrum, no large unreasonable force is applied to the seal ring 17.
Since there is no possibility of early damage, durability can be improved.

Further, since the annular groove 11 is formed in the perfectly circular portion 12 of the piston body 10, the depth of the annular groove 11 is the same on both sides in the longitudinal direction, and the seal ring 17
Since the width of contact with the side surface of the blade is large, the surface pressure is reduced and the intrusion of dirt and the like is reduced.

In addition, the holes 15 and pores 16 of the piston body 10
The high-pressure oil in the cylinder hole 3 acts between the annular groove 11 and the seal ring 17, and the high-pressure oil presses the seal ring 17 against the inner peripheral surface of the cylinder hole 3, which not only improves sealing performance, but also Even if the machining accuracy of the cylinder hole 3 is poor, the seal ring 17 can be pressed against the inner peripheral surface of the cylinder hole 3, and leakage of high pressure oil can be reliably prevented.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a sectional view of a diagonal shaft type axial piston pump/motor, and FIG. 2 being a front view of the piston. 3 is a cylinder hole, 4 is a piston, 10 is a piston body, 11 is an annular groove, 17 is a seal ring, 1
7a is the outer peripheral surface.

Claims (1)

[Scope of utility model registration request] A perfectly circular portion 12 is formed at one end in the longitudinal direction of the piston body 10, and both longitudinally continuous portions continuous with this perfectly circular portion 12 are formed into a tapered shape, and the other end 14 in the longitudinal direction of the piston body 10 is formed in a tapered shape. It has a spherical shape, and an annular groove 11 is formed in the longitudinal middle of the perfectly circular portion 12.
, a spherical outer circumferential surface 1 approximately equal to the inner diameter of the cylinder hole 3;
7a, a hole 15 is bored in the axial center of the piston body 10, and this hole 15 opens into the annular groove 11 with a small hole 16. pump·
motor piston.