JPH0639122Y2 - Fluid pressure piston - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fluid pressure piston having a piston ring having a sealing action and a bearing action on its outer peripheral surface in a hydraulic cylinder or a pneumatic cylinder.

(Prior Art) Conventionally, in a fluid pressure piston, Japanese Patent Laid-Open No. 58-149464
As disclosed in the publication, a piston body made of nylon resin containing carbon fiber is provided on the outer peripheral surface of a piston body made of nylon resin containing glass fiber.

(Problems to be Solved by the Invention) In the conventional fluid pressure piston described above, it is necessary to prevent the piston ring and the piston body from being separated from each other and axially displaced even when a high pressure is applied. Requires a structure in which a plurality of annular projections engaged with a piston ring are further provided in the axial direction and an annular groove is formed between the projections as shown in FIG. 3 of the above publication. Is.

However, since the piston body is made of resin, which has a lower strength than metal, the annular projection is likely to be damaged from the root, especially when high pressure is applied.

Therefore, it is difficult to provide a plurality of annular projections in order to increase the coupling force between the piston ring and the piston body and further increase the height thereof, that is, to make the annular groove deep.

Therefore, an object of the present invention is to eliminate the above-mentioned problems and prevent the two from shifting in the axial direction due to separation even when a high pressure is applied.

(Means for Solving Problems) In order to achieve the above object, a fluid pressure piston according to the present invention has a plurality of annular projections and a plurality of engagement grooves on an outer peripheral surface of a piston body made of reinforced plastic. The taper groove is formed by alternately arranging in the axial direction and is provided at the axial end portion, and has a tapered groove deeper than the engaging groove and having a tapered surface, and has self-lubricating property and elasticity on the outer peripheral side of the piston body. A substantially cylindrical piston ring made of resin is crimped, a plurality of annular projections in which the piston ring engages with the engagement groove, and a bent portion that engages with the tapered groove at one end of the piston ring, The other end of the piston ring is integrally provided with a seal lip that comes into pressure contact with the inner wall of the cylinder.

(Operation) In the fluid pressure piston having the above-described configuration, the groove provided at the axial end portion of the piston body is formed deeper than the other engaging groove, but the tapered groove having the tapered surface should be formed. The strength of the root of the annular projection is secured by the above, and a bent portion is provided on one end of the piston ring to engage with the tapered groove, and a plurality of annular projections of the piston ring and a plurality of outer peripheral surfaces of the piston body are provided. By engaging with the engaging groove, they are firmly engaged with each other, and even when a high pressure is applied, the piston body and the piston ring do not shift in the axial direction due to separation.

(Example) Next, the Example of this invention is described according to drawing.

FIG. 1 shows an embodiment of a fluid pressure piston according to the present invention. The piston is formed of a reinforced plastic such as phenol resin and has a substantially cylindrical shape with a through hole 1a provided in its axial direction. The piston body 1 and a piston ring 2 made of PTFE resin which is crimped and fitted onto the outer peripheral surface of the piston body 1.

A plurality of engagement grooves 3 are formed on the outer peripheral surface of the piston body 1 along the entire circumference in the circumferential direction in the axial direction of the piston body 1. The left end in the axial direction is deeper than the engagement groove 3 and has a tapered surface. A groove 31 having is provided.

The piston ring 2 has a cylindrical shape, the main body portion thereof has a bearing portion 2d, and the inner peripheral surface thereof has a plurality of annular projections 2b formed in accordance with the shape of the engagement groove 3 of the piston main body 1. A bent portion 2a that is bent inwardly of the piston body 1 at one end, and a seal lip that presses against the inner peripheral surface of the cylinder 4 at the other end
2c, which are integrally formed.

The annular protrusion 2b is engaged with an engagement groove 3 formed in the piston body 1 in a plurality of lines.

The bent portion 2a is engaged with a taper groove 31 provided at the axially left end of the piston body 1.

In the fluid pressure piston configured as described above, since the piston ring 2 is molded from PTFE resin,
The friction coefficient of the sliding surface is low.

Furthermore, since the elastic modulus is low and the shrinkability is good, the contact surface pressure is small and the sliding resistance is low.

Further, when the piston slides, the piston ring 2 is pulled in the direction opposite to the sliding direction by the sliding resistance, but the annular projection 2b of the piston ring 2 extends in a direction perpendicular to the sliding direction of the piston. Since it is fitted in the groove 3,
The force applied to the piston ring 2 is carried by the side surface of each engagement groove 3.

Further, since the gap between the outer peripheral surface of the bearing portion 2d of the piston ring 2 and the inner peripheral surface of the cylinder 4 is small, only the seal lip 2c side (the right side of the piston body 1 in FIG. 1) when high pressure is applied. However, the pressure is also applied to the bent portion 2a side (the left side of the piston body 1 in FIG. 1), but the bent portion 2a engages with the taper groove 31 deeper than the engaging groove 3. Therefore, not only when the piston slides, but also when the high pressure acts, the piston ring 2 is less likely to peel off, and the sealing performance is stable.

Furthermore, since the annular projection 2b of the piston ring 2 is in close contact with the engagement groove 3 of the piston body 1, the contact area between the piston ring and the piston body 1 is wide, and as a result, when the piston slides, Even if a lateral load is applied to the piston ring 2, the load applied to the piston ring 2 per unit area is small.

Therefore, the deformation of the piston ring 2 with respect to the lateral load is small, and the axial eccentricity of the piston is reduced.

Since the piston ring 2 is formed into a cylindrical shape by drawing from a flat plate and is crimped to the outer peripheral surface of the piston body 1, the piston body 1 is shown in FIG. Even if there is a stepped portion 5 or a burr (not shown) on a part of the outer circumference, or if the circularity of the piston body 1 is distorted, these can be absorbed.

(Effect of the Invention) The present invention has the following effects.

That is, the fluid pressure piston of the present invention has a plurality of annular projections and a plurality of engagement grooves alternately arranged on the outer peripheral surface of the piston body made of reinforced plastic in the axial direction, and is provided at the axial end portion, A taper groove having a tapered surface is formed deeper than the engagement groove, and a substantially cylindrical piston ring made of resin having self-lubricating property and elasticity is crimped to the outer peripheral side of the piston body, and the piston ring is A plurality of annular projections that engage with the engagement groove, a bent portion that engages with the taper groove at one end of the piston ring, and a seal lip that presses against the inner wall of the cylinder at the other end of the piston ring are integrated. Since it is equipped with a piston ring made of resin such as PTFE having self-lubricating property and elasticity, the PTFE resin has a wear resistance compared to the conventional nylon resin. Is low, it is possible to greatly reduce the sliding resistance.

Further, since the piston ring is engaged with the plurality of annular projections and the plurality of engaging grooves formed on the outer peripheral surface of the piston body, the coupling force between the piston body and the piston ring is increased, and the piston body and Since the piston ring does not move relative to each other, it is possible to prevent the generation of abnormal noise due to the relative movement.

Also, because the bent portion at one end of the piston ring engages with the tapered groove that is deeper than the engaging groove and has a tapered surface, the piston ring is less likely to peel off during high pressure operation or sliding, and the sealing performance is stable. To do.

Further, since the seal lip is integrated with the other end of the piston ring and is in pressure contact with the inner wall of the cylinder, a constant sealing property is always ensured.

If the piston ring is brought into close contact with the engagement part on the outer peripheral surface of the piston body, the contact area between the piston body and the piston ring will be large, so the piston ring will not be affected by the lateral load applied from the cylinder wall surface to the piston ring when the piston slides. Deformation is small and the amount of shaft eccentricity when the piston slides is reduced.

Furthermore, since the piston ring is formed into a cylindrical shape by drawing from a flat plate and is crimped to the outer peripheral surface of the piston body, the piston body may have a stepped portion or a stepped portion on the outer periphery due to misalignment during injection molding. Even if the burr or the circularity of the piston body is distorted, these can be absorbed.

[Brief description of drawings]

FIG. 1 is a half sectional view of a piston according to an embodiment of the present invention, and FIG. 2 is a front sectional view of the piston. Explanation of symbols, 1 ... Piston body, 1a ... Through hole, 1b ...
… Annular protrusion, 2 …… Piston ring, 2a …… Bent part, 2b
…… Annular protrusion, 2c …… Seal lip, 2d …… Bearing part, 3
…… Engagement groove, 31 …… Tapered groove, 4 …… Cylinder, 5 ……
Step.

Claims (1)

[Scope of utility model registration request] 1. A plurality of annular projections (1b) and a plurality of engagement grooves (3) are formed alternately on an outer peripheral surface of a piston body (1) made of reinforced plastic in an axial direction, and end portions in the axial direction are formed. A substantially cylindrical pipe made of a resin having self-lubricating property and elasticity on the outer peripheral side of the piston main body (1), the tapered groove (31) being formed deeper than the engaging groove (3) and having a tapered surface. -Shaped piston ring (2) is crimped, and the plurality of annular projections (2b) that engage with the engagement groove (3) by the piston ring (2) and the taper at one end of the piston ring (2) A bent portion (2a) engaging with the groove (31) and a seal lip (2c) press-contacting the inner wall of the cylinder (4) at the other end of the piston ring (2) are integrally provided. Characteristic fluid pressure piston.