JP2563216Y2 - Pneumatic cylinder sealing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic cylinder used in a manufacturing facility or the like, and more particularly to a sealing device for a piston or the like of a pneumatic cylinder.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, an annular groove 10 is formed in a piston 3 which is slidably fitted in a hollow cylinder 2.
And the O-ring 15 and the resin ring 1 are formed in the annular groove 10.
4 is superposed and stored, for example, in
It is known from JP 33005. Next, the operation of the sealing device for a pneumatic cylinder having the above configuration will be described. The pressure of the fluid is applied to the side surface of the resin ring 14, and the resin ring 14 moves in the axial direction to introduce the pressure of the fluid to the O-ring. The pressure of the fluid causes the O-ring to be deformed, and the resin ring is moved outward. Let it expand. The resin ring 14 pressed against the inner wall of the cylinder receives the pressure of the fluid acting when the piston slides to seal the fluid.

Since the O-ring 15 is made of rubber, it can be fitted into the annular groove 10 by extending the inner circumference. However, since the resin ring 14 is hardly elastically deformed, a cut 16 is provided to fit into the annular groove of the piston.

[0004]

However, almost no consideration has been given to the leakage of fluid from the cut of the resin ring in the prior art. Therefore, even if the leakage of the fluid between the resin ring and the cylinder inner wall is reduced,
There was a problem that the movement of the piston lacked smoothness due to leakage from the cut of the resin ring. That is, although the shapes of the cutouts are various, all of the cutouts are obtained by cutting a part of the ring, so that a slight gap is generated even after the mounting. Even if the resin ring is expanded outward, this gap does not close, so when pressurized fluid comes into contact with the piston,
Fluid leakage has occurred from this gap, that is, the notch joint.

In the conventional sealing device, the sliding surface on the outer periphery of the resin ring is excessively pressed against the inner wall of the cylinder, so that the sliding resistance of the resin ring increases, and the movement of the piston cannot be accurately controlled. There was a problem. In addition, there is a problem that extra air pressure is required, the diameter of the piston needs to be increased, and the size and cost of the device increase.

The present invention has been made to solve the above-described problems, and has as its object to reduce leakage from a notch opening of a resin ring and improve slidability of an outer peripheral portion. I do.

[0007]

In order to achieve this object, a sealing device for a pneumatic cylinder according to the present invention comprises a pneumatic cylinder having a hollow cylindrical cylinder and a piston slidably fitted in the cylinder. A cylinder, wherein an annular groove is formed on the outer periphery of the piston, and a continuous elastic body ring disposed on the inner side of the annular groove and a discontinuous ring disposed on the outer side of the annular groove. The resin ring is housed in a state of being overlapped with the resin ring, and an elastic body is incorporated in a joint portion of the cut of the resin ring. Further, the outer peripheral portion of the elastic body is subjected to a surface treatment.

[0008]

The sealing device for a pneumatic cylinder according to the present invention having the above-described structure injects air into one of the cylinder chambers interrupted by the piston in the cylinder to apply air pressure to the piston to move the piston in an arbitrary direction. At this time, a static pressure of fluid is applied to the piston and a dynamic pressure due to the movement of the piston also acts, so that air leakage easily occurs between the piston and the cylinder. A continuous elastic body is elastically deformed and mounted in an annular concave groove formed in the piston, and a resin ring having a discontinuity is mounted on an outer periphery thereof so as to be in contact with the elastic body.

When air pressure is applied to the piston from one direction, the elastic ring and the resin ring are pressed against the surface of the annular groove opposite to the direction in which the air pressure is applied by the air pressure. Further, the elastic ring is crushed by air pressure, and urges the resin ring to expand the resin ring outward and press it against the inner wall of the cylinder. This prevents leakage of air from between the outer periphery of the piston and the inner wall of the cylinder. There is a cut in the resin ring to fit into the annular groove, but the elastic body built in between the cuts contacts the cut surface of the resin ring, preventing air leakage from the cut in the resin ring. prevent. Since the elastic body between the cuts also slides in the cylinder together with the piston, the surface resistance is applied to the outer peripheral part of the elastic body to reduce the sliding resistance.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a pneumatic cylinder 1 utilizing the present invention. Hollow cylinder body 2
The piston 3 is slidably fitted in the hollow portion of the piston.
A piston rod 4 is formed at the center of one end face of the piston 3 perpendicular to the end face. The end of the piston rod 4 protrudes outside through a hole formed at one end of the cylinder body 2. A left air pressure port 8 is formed in the left chamber 6 on the left side of the piston 3 of the cylinder body 2 for inflow or outflow of driving air. The right chamber 5 on the rod side of the piston 3 of the cylinder body 2 is provided with a right air pressure port 7 for inflow or outflow of driving air.

An annular groove 10 is formed on the outer periphery of the piston 3. A ring-shaped O-ring 15 formed of rubber, which is an elastic body, is attached to the annular groove 10 in close contact with the annular groove 10. Further, a resin ring 14 formed of a resin material having a small coefficient of friction, for example, Teflon or the like, is mounted outside the O-ring 15. In the hole of the cylinder body 2 where the piston rod 4 protrudes, an annular groove 12 is provided on the inner circumference of the cylinder surrounding the piston rod 4, and an O-ring 11 is provided.

Next, the resin ring 1 which is a main part of the present invention will be described.
4 will be described with reference to FIG. FIG. 2 is a plan view of the notch 16 of the resin ring 14. Resin ring 1
In order to fit into the annular groove 10 of the piston 3,
One step-shaped notch 16 is formed. The notch 16 has a slightly long notch 16a formed in the center of the resin ring 14 in the longitudinal direction, and the long notch 16a forms a wide space. Both ends of notch 16 are resin ring 1
4 are connected to both sides by short notches 16b. An elastic body 17 is incorporated in a long notch 16a in a wide space at the center of the notch 16, so that both ends contact a short notch 16b in the longitudinal direction.

FIG. 3 is a sectional view of the notch 16 including the elastic body 17. Here, the elastic body 17 uses nitrile rubber (NBR) as a material. On the outer peripheral surface of the elastic body 17 that is in contact with the cylinder body 2, a surface treatment layer 18 that is halogenated or the like for improving slidability is formed. The elastic body 17 slides on the inner surface of the cylinder body 2 together with the piston 3. However, the elastic body 17 has poor slidability as it is compared with the resin ring 14 having good slidability. This can prevent the slidability from being reduced due to the incorporation of the elastic body 17.

FIG. 3 is a sectional view taken along line AA of FIG. 2, showing a state in which the piston 3 is fitted into the cylinder body 2.
The O-ring 15 is compressed and deformed. At this time, when the O-ring 15 and the resin ring 14 are assembled, the width A of the elastic body 17 is set to satisfy A <B with respect to the width B at which the O-ring 15 contacts the resin ring 14. Elastic body 1
7 is the width B at which the O-ring 15 contacts the resin ring 14.
By making it smaller, the O-ring 15 always contacts the resin ring 14. Therefore, when the O-ring 15 is deformed by the inflow of the pressurized air, the deformation of the O-ring 15 allows the notch 16 to press not only the elastic body 17 but also the resin ring 14 body against the cylinder. Leakage from the part can be prevented.

On the other hand, when the O-ring 15 is deformed by the inflow of pressurized air, the elastic body 17 fitted into the notch 16 of the resin ring 14 is pressed by the deformed O-ring 15 to be compressed. The notch portion 16 is partially deformed to close the entrance of the short notch 16b of the notch portion 16. The elastic body 17
As a result, leakage from the notch 16 is prevented. At this time, since the elastic body 17 is partially deformed, the pressure at which the elastic body 17 is pressed against the inner wall of the cylinder main body 2 increases. In this embodiment, however, the surface of the elastic body 17 that is in contact with the cylinder main body 2 has a surface treatment layer. Since the friction member 18 is formed, the frictional force does not change much even if the pressing pressure increases, so that the piston 3 can slide smoothly.

As described above, according to the pneumatic cylinder sealing device of this embodiment, the inner surface of the cylinder body 2 and the piston 3 are formed by the set of the O-ring 15 and the resin ring 14 fitted in the annular groove 10 of the piston 3. Prevent air leakage between the outer circumference of the car. In the notch 16 of the resin ring 14,
By fitting the elastic body 17 having a width not exceeding the width of the O-ring 15, the leakage of air passing through the notch 16 is prevented. In addition, by performing a surface treatment on the outer peripheral portion of the elastic body 17 in the cutout portion 16 to enhance the slidability, a decrease in the slidability due to the incorporation of the elastic body 17 can be avoided. Therefore, the air pressure applied to the air pressure port 7 or 8 in order to obtain the necessary movement of the piston 3 can be smaller than in the prior art.

The present invention is not limited to this embodiment,
Various modifications are possible. That is, in this embodiment, a normal O-ring is used as a sealing device for the rod portion. However, if the sealing device of the present invention is used instead of the O-ring, the sealing effect is further improved.

[0018]

As is apparent from the above description, according to the pneumatic cylinder sealing device of the present invention, an annular groove is formed on the outer periphery of the piston, and the cut is provided on the inner side of the annular groove. Since the elastic body ring without and the resin ring with a cut disposed outside the annular concave groove are housed in a superposed state, and the elastic body is incorporated in the joint portion of the cut of the resin ring, Since leakage occurring at the notch can be prevented and the sealing performance can be improved, the performance of the pneumatic cylinder can be improved and the cost can be reduced. Further, since the outer peripheral portion of the elastic body is subjected to a surface treatment, the frictional force when the elastic body is pressed against the inner wall of the cylinder can be reduced, and the slidability of the piston can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a pneumatic cylinder using a pneumatic cylinder sealing device embodying the present invention.

FIG. 2 is a plan view of a cutout alignment opening of a resin ring.

FIG. 3 is a cross-sectional view of an O-ring and a resin ring in an annular groove.

FIG. 4 is a sectional view of a conventional sealing device.

[Explanation of symbols]

 2 Cylinder main body 3 Piston 10 Annular concave groove 14 Resin ring 15 Elastic body ring 16 Notch 17 Elastic body 18 Surface treatment layer

Claims (1)

(57) [Scope of request for utility model registration] 1. A pneumatic cylinder having a hollow cylindrical cylinder and a piston slidably fitted in the cylinder, wherein an annular groove is formed on an outer periphery of the piston. The elastic body ring provided on the back side and the resin ring provided on the outside in the annular groove are housed in a state of being overlapped, and the joint portion of the resin ring is provided with a cut. comprises-out parallel notch and a cylinder section, the write set a rectangular parallelepiped elastic body notch Mutotomoni, the width a of the cutout piston movement direction, the resin phosphorous
A sealing device for a pneumatic cylinder, wherein a width of the ring is smaller than a width B in contact with the elastic ring .