JPS6020801Y2 - Piston device for fluid pressure cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston device in which a lip seal attached to the outer periphery of a piston of a fluid cylinder is provided with a device for releasing pressure between the piston outer periphery and the tongue seal.

In order to maintain airtightness between the piston moving inside the cylinder and the inner surface of the cylinder, a lip seal with low sliding resistance is sometimes provided on the outer periphery of the piston.

Since this lip seal has directionality depending on the direction of the lip, it is necessary to symmetrically attach at least one pair of lip seals to a reciprocating piston.

By the way, when the piston is subjected to air pressure alternately on both end faces and reciprocates repeatedly, air leaking from the lip of the seal accumulates between the pair of glue seals, but this is because the lip of the seal has a certain degree of rigidity. Therefore, the pressure air accumulated between the seals is not necessarily discharged to the outside.

When the seal a is deformed as shown in Fig. 1 due to the reciprocating movement of the piston, the accumulated air pressure acts like Pl and P2 from the inner peripheral surface and one end surface of the seal a to deform the seal. This results in pressure bonding to the inner surface of the cylinder body, which in turn causes it to stick.

As a result, the problem arises that the movement of the piston is restricted, which is particularly noticeable in small diameter cylinders due to the small thrust force.

As a means to solve such problems,
There is a structure described in Japanese Patent No. 97, but this structure requires a passage for pressure relief to be provided in the piston and the outer circumference of the piston, which increases the processing cost accordingly.

The present invention was devised in view of this problem, and its purpose is to simplify the structure of the piston device and reduce costs by providing a means for releasing pressure to the lip seal attached to the outer periphery of the piston. It is to aim for.

The present invention includes a piston that is movably disposed within a cylinder and has a pair of seal grooves spaced apart from each other in the axial direction on the outer periphery of the piston.
The inner circumferential surface of the base is placed in the seal groove with the inner circumferential surface of the base in contact with the bottom surface of the seal groove, and the lip that extends diagonally outward in the radial direction from the base comes into contact with the inner circumferential surface of the cylinder or the lip seal is attached to the bottom surface of the seal groove. In the piston device for a fluid pressure cylinder, the axial width of the lip seal is made smaller than the axial width of the seal groove to create a gap between the lip seal side surface and the seal groove side surface, and A groove extending in the axial direction of the lip seal is formed on the inner periphery, and the groove is capable of contacting the bottom surface of the seal groove to allow fluid to flow toward the outside of the piston from the gap between the pair of lip seals. A lip that separates from the bottom surface only when the piston is in use is formed integrally with the base, and a ring-shaped protrusion partially cut out with a groove is formed on the side surface of the base facing the end surface of the piston. ing.

In the piston device configured as described above, when the fluid pressure in the gap between the pair of lip seals is less than a predetermined value compared to the pressure at both ends of the piston, the lip of the groove comes into contact with the bottom surface of the seal groove of the piston, and the lip of the groove comes into contact with the bottom surface of the seal groove of the piston. However, when the pressure in the gap exceeds a predetermined value, the lip of the lip seal on the low pressure side is deformed and separated from the bottom surface, and the groove and the notch in the ring-shaped protrusion are Fluid flows to the low pressure side through the

An embodiment of the piston according to the present invention will be described below with reference to the drawings.

An embodiment of a piston device according to the present invention is shown in FIGS. 2 and 5. FIG.

In the figure, 1 is a piston, and 2 is a cylinder body into which the piston 1 is inserted.

A pair of seal grooves 11 and 12 are formed on the outer periphery of the cylindrical main body 10 of the piston 1 and are spaced apart from each other in the axial direction, and a lug seal 3 is fitted into the seal grooves.

As shown in detail in FIGS. 3 to 5, the lip seal 3 has an annular base 30, extends obliquely outward in the radial direction from the base 30, and engages with the inner circumferential surface 20 of the cylinder body 2. The outer circumferential knob 31 and the base 30
It has an annular convex portion 32 formed to protrude in the axial direction on one side surface (the surface on the end surface side of the piston).

One or more grooves 33 are formed in the inner peripheral surface of the base 30 of the lip seal, and notches 34 are formed in the protrusion 32 at positions corresponding to the grooves.

A lip 35 is integrally formed at the notch side end of *33.

The axial width of the lip seal 3 is smaller than the axial width of the seal grooves 11 and 12, and when the lip seal is pushed toward the convex portion within the seal groove, the side surface of the base (where the convex portion 32 is formed) As shown in FIG. 2, a gap is formed between the side surface (not shown) and the side surface of the seal groove.

When the lip seal is fitted into the seal groove 11 or 12, the groove 33 and the notch 34 are arranged so that when the lip seal is fitted into the seal groove 11 or 12, the gap G between the pair of lip seals is limited by the piston 1 and the cylinder body 2. It constitutes a means or passage 4 for communicating with the piston chambers C1 and C2.

In addition, the lip 35 has a tip, that is, an inner radial edge on the same circumferential surface as the inner circumferential surface of the base, and the lip seal is installed in the seal groove, and the pressure in the gap G is lower than the external pressure. When the pressure is not too high, it is in contact with the bottom of the seal groove, and when the pressure inside the gap G becomes higher than the external pressure by more than a predetermined value, the tip separates from the bottom of the seal groove and opens the passage 4.
It allows fluid to flow to the low pressure side, for example to the piston chamber C1 or C2 side, and acts as a kind of check valve.

In the piston of this embodiment, when fluid pressure is supplied to the piston chamber C□ and becomes the high pressure side, and the piston chamber C2 becomes the low pressure side, the piston 1 moves in the direction of arrow A, but within the gap G. When the pressure exceeds a predetermined value, the inner peripheral edge of the lip 35 separates from the bottom surface of the seal groove, and the fluid pressure flows into the piston chamber C2 on the low pressure side through the passage 4 consisting of the groove 33 and the notch 34.

Therefore, the pressure within the gap G will not become too high.

According to the present invention, a pressure relief groove and a lip that act as a check valve are formed in the lip seal itself, so there is no need to form a special passage in the piston and piston external door as in the device described in the above-mentioned publication. , the structure of the cylinder can be simplified and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a conventional piston, FIG. 2 is a partial sectional view of a piston device according to an embodiment of the present invention, FIG. 3 is a front view of a seal of the piston device of FIG. 2, and FIG. Third
FIG. 5 is a cross-sectional view taken along line IV--IV in the figure, and is a view taken along line ■--■ in FIG. 1: Piston device, 2 Pusheal, 4: Passage, 50 Tube, 33: Groove, 35 Niji cylinder body, 3: Lip: Check valve, 6: Piston: Lip.

Claims (1)

[Scope of utility model registration request] A piston is movably disposed within a cylinder and has a pair of seal grooves formed on its outer periphery spaced apart from each other in the axial direction; In a piston device for a fluid pressure cylinder, the lip extends diagonally outward in the radial direction from the base and comes into contact with the inner circumferential surface of the cylinder, and includes a tongue seal,
The axial width of the lip seal is made smaller than the axial width of the seal groove to create a gap between the lip seal side surface and the seal groove side surface, and the inner periphery of the base is provided with a groove extending in the axial direction of the lip seal. An extending groove is formed in the groove, and the groove has a lip that is capable of contacting the bottom surface of the seal groove and that separates from the bottom surface only when fluid is allowed to flow toward the outside of the piston from the gap between the pair of lubricant seals. A piston device for a fluid pressure cylinder, characterized in that the piston device is integrally formed and has a ring-shaped convex portion partially cut out by a groove on the side surface of the base portion facing the end surface side of the piston.