JPH0512516Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a piston used in a shock absorber or the like.

[Conventional technology]

Conventionally, as shown in Japanese Unexamined Patent Publication No. 149464/1983, a piston has been created in which the part that slides with the cylinder hole is made of a low-friction material, the remaining part is made of a high-strength material, and both parts are integrated. Are known.

[The problem that the idea aims to solve]

Although the above-mentioned conventional piston has improved sliding characteristics and strength characteristics in accordance with the principle of putting the right material in the right place, the following problems remain. That is, since the two parts are not provided with means for engaging each other, even if the two parts are integrated, when high pressure is applied to the piston, the two parts will separate and shift in the axial or circumferential direction. There is a possibility. Regarding the direction of the pressure that acts on the piston, it is possible to reduce the pressure that acts from the front side of the piston with a sealing member, but it is possible to reduce the pressure that acts from the back side of the piston with a sealing member. I can't deal with this because I don't have one. Therefore, if high pressure is applied directly to the piston from the back pressure side, the high pressure will enter between the two parts like a wedge, causing the two parts to separate and shift in the axial or circumferential direction. A solution is needed.

[Means to solve the problem]

In view of the above points, the present invention was devised for the purpose of solving the problems remaining in the above-mentioned prior art. the groove extends in a direction crossing the axial direction or the circumferential direction; The inner circumferential portion of the cylindrical sealing material inserted and fixed onto the piston body is engaged with the plurality of grooves, and an annular flange portion is integrated with the axial end of the cylindrical sealing material toward the inner circumferential direction. A piston is provided, characterized in that the piston is molded and the flange portion is engaged with the annular groove.

[Effect]

The inner circumferential portion of the cylindrical seal material is engaged with a plurality of grooves formed on the outer circumferential surface of the piston body to prevent the piston body and the cylindrical seal material from shifting. The grooves extend transversely to the axial or circumferential direction and thus prevent slippage in that direction. An annular flange formed integrally with the axial end of the cylindrical seal member toward the inner circumferential direction is engaged with an annular groove formed at the axial end of the outer circumferential surface of the piston body to act on the piston. To prevent back pressure from entering between the piston body and the cylindrical sealing material like a wedge. The flange portion receives back pressure and comes into pressure contact with the inner wall of the annular groove, thus providing a sealing effect.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

In the first embodiment shown in FIGS. 1 and 2, the outer peripheral surface of the maximum outer diameter portion of the piston body 1 has a plurality of grooves (four in the figure) extending in the circumferential direction. ) is formed, and outside this,
A plurality of grooves 3 extending in the axial direction are formed at equal intervals at the same depth so as to intersect each of the grooves 2 (8 in the figure).
An annular groove 4 is formed slightly deeper than the grooves 2 and 3 at the axial end (left end in FIG. 1) of the outer circumferential surface of the piston body 1. A cylindrical sealing material 5 is fitted and fixed on the outer peripheral side of the piston body 1, and the inner peripheral part 6 of the cylindrical sealing material 5 engages with each of the grooves 2 and 3, and the axial direction of the cylindrical sealing material 5 An annular flange portion 7 is integrally molded at the end portion (the left end portion in FIG. 1) toward the inner circumferential direction, and the flange portion 7 engages with the annular groove 4. 8
is a seal lip integrally formed on the other axial end of the cylindrical seal member 5. The cylindrical sealing material 5 is made of polytetrafluoroethylene resin (PTFE), which has excellent sliding properties, and the piston body 1 is made of a material that can be molded by injection or the like.

The piston with the above configuration is assembled into a cylinder tube (not shown), and slides in the axial direction under pressure with the right side in FIG. Because the inner peripheral part 6 of the cylindrical seal material 5 is engaged with the plurality of grooves 2 and 3 formed in the piston body 1 and the cylindrical seal material 5 are separated even if high pressure is applied, the piston body 1 and the cylindrical seal material 5 may separate in the axial direction or circumferential direction. In particular, with respect to pressure applied from the back side, the flange portion 7 comes into pressure contact with the inner wall of the annular groove 4 and exerts a sealing action, so that the pressure is applied to the piston body 1 and the cylindrical seal member 5. This prevents the material from entering the space like a wedge, thereby producing excellent effects. In the second embodiment shown in FIG. 3, a plurality of spiral grooves 9 and 10 are formed on the outer circumferential surface of the piston body 1 in place of the grooves 2 and 3, and intersect with each other. It has the same effect as.

[Effect of idea]

The present invention has the following effects. In other words, since the inner circumference of the cylindrical seal material is engaged with the plurality of grooves formed on the outer circumferential surface of the piston body, even if high pressure is applied, the piston body and the cylindrical seal material may separate, causing damage in the axial or circumferential direction. It can prevent it from shifting in the direction,
In particular, since the flange portion presses against the inner wall of the annular groove to perform a sealing action against pressure applied from the back side, pressure is prevented from entering between the piston body and the cylindrical sealing material like a wedge, It is possible to prevent the piston body and the cylindrical sealing material from peeling off and shifting in the axial or circumferential direction.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view of a piston according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along the line -- in FIG. 1, and FIG. It is a front view. 1... Piston body, 2, 3, 9, 10...
Groove, 4... Annular groove, 5... Cylindrical sealing material, 6...
Inner peripheral part, 7...flange part, 8... seal lip.

Claims (1)

[Scope of utility model registration request] A plurality of grooves 2, 3,
The grooves 2, 3, 9, and 10 extend in a direction crossing the axial direction or the circumferential direction, and an annular groove 4 is formed at the axial end of the outer peripheral surface of the piston body 1. The plurality of grooves 2, 3, 9, 10
The inner peripheral part 6 of the cylindrical sealing material 5 which is formed separately from the piston body 1 and is externally fixed to the piston body 1 is engaged with the plurality of grooves 2, 3, 9, 10, and the cylindrical sealing material 5 is
A piston characterized in that an annular flange portion 7 is integrally molded at an axial end portion of the piston in a substantially inner circumferential direction, and the flange portion 7 is engaged with the annular groove 4.