JPH047372Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is an air cylinder in which the piston is reciprocated within the cylinder by intake and exhaust at one end of the cylinder. , relates to a sealing device that maintains airtightness.

[Conventional technology]

An example of a conventional air cylinder 21 of this type will be explained based on FIGS. 2 and 3.

The opening of the bottomed bore 23 of the cylinder 22 is closed by a cover 25 fixed to the opening edge of the cylinder 22 by bolts 24.

The bore 23 of the cylinder 22 has a crested hole, and the outer surface of the lower end of the side wall 26b is formed into a tapered arcuate surface 26.
A piston 26 denoted by c is fitted, and an air chamber 27 of variable volume is formed between the top plate 26a and the cover 25.

The piston 26 has its top plate 26a and the cylinder 2
It is biased upward by a compression spring 28 inserted between the bottom plate 22a of No. 2 and the bottom plate 22a of No. 2.

A supply/exhaust pipe 29 is connected to the cover 25 .

By supplying and exhausting air into the air chamber 27, the piston 26
moves back and forth up and down.

The lower end of the piston rod 31 whose upper end is fixed to the lower surface of the top plate 26a of the piston 26 is connected to the cylinder 22.
It passes through the bottom wall 22a of the holder and is connected to an operating member of an appropriate device (not shown).

A slightly larger diameter ring groove 32 is formed at the lower end of the inner circumferential surface 22b of the cylinder 22, and the O-ring 33 fitted therein contacts the tapered arcuate surface 26c on the outer surface of the lower end of the piston 26. Airtightness between the piston 22 and the piston 26 is maintained.

[Problem that the invention attempts to solve]

In the conventional sealing device for the air cylinder 21 described above, there is no means for preventing the O-ring 33 from protruding inward, so there is a risk that the O-ring 33 may protrude inward during load.

In particular, the outer tapered arcuate surface 26c of the cylinder 26
When pressed against the inner periphery of the O-ring 33, the inner periphery 22 of the cylinder 22 as shown by the arrow in FIG.
Air leaking from between b and the outer peripheral surface 26b of the piston 26 wraps around the outer peripheral side of the O-ring 33,
This causes a phenomenon in which a part of the O-ring 33 is pushed inward.

The deformed portion of the O-ring 33 that has been pushed out is strongly pressed by the tapered arc surface 26c of the piston 26, and there is a great possibility that the O-ring 33 will be worn out.

[Means for solving problems]

In the present invention, a piston biased toward the air chamber is fitted into a cylinder having an air chamber at the upper end that is appropriately supplied and exhausted, so that the piston can move vertically, and the piston is attached to the inner lower part of the cylinder from the outer diameter of the piston. By fitting a cylindrical stopper with a small outer diameter, the lower end surface of the piston comes into contact with the upper end surface of the stopper when the piston is lowered, and An annular groove with a square surface,
A ring-shaped gasket with a rectangular longitudinal section is fitted into the annular groove on the inner peripheral surface of the cylinder, with its lower part press-fitted between the outer peripheral surface of the stopper. To provide a sealing device for an air cylinder, which prevents the inner peripheral portion of the gasket from protruding inward, thereby preventing damage to the gasket.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIG.

In FIG. 1, parts that perform the same functions as those of the conventional air cylinder are designated by the same reference numerals, and their explanations will be omitted.

A piston 26 having a capped hole 2a is fitted into the bottomed bore 1a of the cylinder 1.

The lower part of the bore 1a of the cylinder 1 is a holding hole 1b with a slightly small diameter, and the holding hole 1b has an upper end surface 3a against which the lower end surface 26d of the piston 26 can come into contact.
A bottomed cylindrical stopper 3 having a bottomed hole 2b is fitted therein.

The boundary surface 4 between the bore 1a and the holding hole 1b is located at approximately the same position as the upper end surface 3a of the stopper 3.

On the inner peripheral surface of the cylinder 1 with the boundary surface 4 in between,
An annular groove 5 having a rectangular longitudinal section is formed.

An annular gasket 6 having a rectangular longitudinal section is fitted into the annular groove 5. A part of the gasket 6 is connected to the inner surface 5a of the annular groove 5 and the outer circumferential surface 3 of the stopper 3.
b and is prevented from protruding inward.

The upper end 6a of the inner edge of the gasket 6 can be pressed against a tapered arcuate surface 26c at the lower end of the outer peripheral surface 26b of the piston 26 when the piston 26 is lowered.

[Effect of idea]

Since the gasket 6 has a rectangular longitudinal section, it is essentially difficult to protrude inward.
Moreover, a part of the inner circumference of the gasket 16 is reliably prevented from protruding inward by the outer circumferential surface 3b of the stopper 3, so that when the piston 26 descends, the tapered arcuate surface 26c at the lower end of the outer circumferential surface 26b
can be uniformly pressed against the inner circumferential surface of the gasket 6, and wear and tear on the gasket 6 can be prevented.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of an air cylinder equipped with an example of the sealing device of the present invention, FIG. 2 is a vertical sectional view of an air cylinder equipped with a conventional sealing device, and FIG. FIG. 3 is an enlarged longitudinal cross-sectional view of the sealing device of FIG. DESCRIPTION OF SYMBOLS 1... Cylinder, 1a... Bore, 1b... Holding hole, 2a... Capped hole, 2b... Bottomed hole, 3... Stopper, 3a... Upper end surface, 3b... Outer peripheral surface, 4...
... Boundary surface, 5 ... Annular groove, 5a ... Inner surface, 6 ...
Gasket, 21...Air cylinder, 22...Cylinder, 22a...Bottom wall, 22b...Inner peripheral surface, 2
3...Bore, 24...Bolt, 25...Cover,
26... Piston, 26b... Outer circumferential surface, 26c...
... Tapered arc surface, 26d ... Lower end surface, 27 ... Air chamber, 28 ... Compression spring, 29 ... Supply and exhaust pipe, 31
... Piston rod, 32 ... Ring groove, 33 ... O
ring.

Claims (1)

[Scope of utility model registration request] A piston biased toward the air chamber is fitted into a cylinder having an air chamber at the upper end that is appropriately supplied and exhausted, and is movable up and down, and at the inner lower part of the cylinder,
By fitting a cylindrical stopper having an outer diameter smaller than the outer diameter of the piston, the lower end surface of the piston comes into contact with the upper end surface of the stopper when the piston is lowered, and An annular groove with a rectangular vertical cross section sandwiching the upper end surface is provided on the inner circumferential surface of the cylinder, and a ring-shaped gasket with a rectangular longitudinal cross section is placed in this annular groove, and its lower part is placed between the outer circumferential surface of the stopper and the outer circumferential surface of the stopper. A sealing device for an air cylinder characterized by being fitted in a press-fitted state.