JP2010038328A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device which can reduce sliding resistance and realize excellent mold releasability. <P>SOLUTION: A sealing device 10 for sealing an annular gap between a piston rod and cylinder in an air pressure cylinder keeps a seal lip 12 extending toward a sealing area side sealing air therein and freely slidably brought into close contact with an outer peripheral surface of the piston rod, and a plurality of protrusions 13 extending in a reciprocating direction of the piston rod and cylinder on an inner peripheral surface. A plurality of protrusions 13 are provided so as to extend from a position on an end surface opposite to the sealing area to a position not reaching a chip of the seal lip 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sealing device used for a pneumatic cylinder.

  A pneumatic cylinder is provided with a sealing device that seals an annular gap between the piston rod and the cylinder. Here, there is known one in which a sealing system including a plurality of sealing devices is mounted on each of a piston rod side and a cylinder side. For example, as a sealing system mounted on the piston rod side, a system composed of a piston packing, a wear ring, and a contamination seal is known.

  In addition, as a sealing system mounted on the cylinder side, a rod packing mainly responsible for preventing air leakage, a buffering mainly responsible for pressure resistance, and a dust seal mainly responsible for preventing entry of foreign matter from the outside What is made up of is known.

  With reference to FIG. 9, the rod packing which concerns on a prior art example is demonstrated. FIG. 9 is a schematic cross-sectional view of a rod packing according to a conventional example.

  The rod packing 800 according to this conventional example includes seal lips 801 and 802 on the outer peripheral side and the inner peripheral side, respectively. The rod packing 800 is mounted in an annular groove provided on the inner periphery of the cylinder. The outer peripheral seal lip 801 is in close contact with the bottom surface of the annular groove, and the inner peripheral seal lip 802 is slidably in close contact with the outer peripheral surface of the piston rod.

  Here, in the case of a pneumatic cylinder, it is generally used in a low pressure environment as compared with a case of a hydraulic cylinder. For example, it is used in an environment where the maximum pressure of air pressure is about 1 MPa. Therefore, in the case of a pneumatic cylinder, it is often required to make the sliding resistance as low as possible within a range that does not adversely affect the sealing performance. Lowering the sliding resistance not only reduces mechanical loss, but also improves the life of the sealing device by suppressing heat generation due to sliding resistance.

  Therefore, it is required to further reduce the sliding resistance in the rod packing. FIG. 10 is a schematic cross-sectional view of a rod packing that reduces sliding resistance.

  Also in the rod packing 900 according to the conventional example shown in FIG. 10, seal lips 901 and 902 are provided on the outer peripheral side and the inner peripheral side, respectively. In the case of this rod packing 900, a plurality of annular grooves 903 are provided on the inner peripheral surface of the seal lip 902 on the inner peripheral side.

  According to this rod packing 900, the area of the sliding portion can be reduced, and the use of the annular groove 903 as the grease reservoir can suppress the grease breakage, and the sliding resistance can be suitably reduced. It becomes possible.

However, in order to mold this rod packing 900, the mold must be provided with an undercut at a portion where a plurality of annular grooves 903 are formed. Accordingly, the releasability is poor and it may cause molding defects.
Japanese Utility Model Publication No. 4-101074 JP 2004-286090 A

  An object of the present invention is to provide a sealing device that can reduce sliding resistance and is excellent in releasability.

  The present invention employs the following means in order to solve the above problems.

That is, the sealing device of the present invention is
In a sealing device for sealing an annular gap between a piston rod and a cylinder in a pneumatic cylinder,
A seal lip that extends toward the sealed area where air is sealed and that slidably adheres to the outer peripheral surface of the piston rod,
The inner peripheral surface is provided with a plurality of convex portions extending in the reciprocating direction of the piston rod and the cylinder,
The plurality of convex portions are provided so as to extend from the position of the end surface opposite to the sealing region to a position not reaching the tip of the seal lip.

  According to the present invention, a plurality of convex portions are provided on the inner peripheral surface of the sealing device. Therefore, the area of the sliding portion relative to the outer peripheral surface of the piston rod on the inner peripheral surface of the sealing device can be reduced, and the sliding resistance can be reduced. And these some convex part is provided so that it may extend to the position which does not reach the front-end | tip of a seal lip. Therefore, since the tip of the seal lip is slidably contacted with the outer peripheral surface of the piston rod over the entire circumference, the sealing performance is not hindered by the plurality of convex portions. Further, since the plurality of convex portions are configured to extend in the reciprocating direction between the piston rod and the cylinder from the position of the end surface opposite to the sealing region, the sealing device can be provided without providing an undercut in the molding die. Can be molded, and is excellent in releasability.

Moreover, the sealing device of the present invention comprises:
In a sealing device for sealing an annular gap between a piston rod and a cylinder in a pneumatic cylinder,
A seal lip that extends toward the sealed area where air is sealed and that slidably adheres to the outer peripheral surface of the piston rod,
A plurality of recesses extending in the reciprocating direction between the piston rod and the cylinder are provided on the inner peripheral surface,
The plurality of recesses are provided so as to extend from a position of the end surface opposite to the sealing region to a position not reaching the tip of the seal lip.

  According to the present invention, the inner peripheral surface of the sealing device is provided with a plurality of recesses. Therefore, the area of the sliding portion relative to the outer peripheral surface of the piston rod on the inner peripheral surface of the sealing device can be reduced, and the sliding resistance can be reduced. And these some recessed part is provided so that it may extend to the position which does not reach the front-end | tip of a seal lip. Therefore, since the tip of the seal lip is slidably adhered to the outer peripheral surface of the piston rod over the entire circumference, the sealing performance is not hindered by the plurality of recesses. Further, since the plurality of recesses are configured to extend from the position of the end surface opposite to the sealing region in the reciprocating direction of the piston rod and the cylinder, the sealing device can be provided without providing an undercut in the mold. It can be molded and has excellent releasability.

  As described above, according to the present invention, it is possible to reduce the sliding resistance and provide a sealing device excellent in releasability.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

Example 1
<Pneumatic cylinder>
First, an example of a pneumatic cylinder to which a sealing device according to an embodiment of the present invention is applied will be described with reference to FIG. FIG. 1 is a partially broken perspective view of a pneumatic cylinder.

  The pneumatic cylinder 500 includes a piston rod 200 and a cylinder 300. Sealing systems S <b> 1 and S <b> 2 that seal the annular gap between the piston rod 200 and the cylinder 300 are provided at two locations separated in the axial direction of the pneumatic cylinder 500. As a result, two sealed regions K1, K2 are formed between the piston rod 200 and the cylinder 300.

  The sealing system S1 includes a piston packing 100a, a wear ring 100b, and a contamination seal 100c. These are all mounted in an annular groove provided on the piston rod 200 side. Further, the sealing system S2 includes a rod packing that is the sealing device 10 according to the embodiment of the present invention, a buffer ring 10X, and a dust seal 10Y. These are all mounted in an annular groove provided on the cylinder 300 side. The rod packing mainly plays a role of preventing air leakage, the buffer ring 10X mainly plays a role of pressure resistance, and the dust seal 10Y mainly plays a role of preventing entry of foreign matters from the outside.

  With such a configuration, the piston rod 200 is reciprocated relative to the cylinder 300 by controlling the air pressures P1 and P2 of the air fed into the sealed regions K1 and K2 from the openings 301 and 302 provided in the cylinder 300, respectively. Can be made.

  The sealing device 10 according to the present embodiment is suitable as a sealing device (rod packing) mainly having a function of preventing air leakage in the sealing system S2 in which one side in the axial direction is a sealed region K1 and the other side is the atmosphere. Used for.

<Sealing device (rod packing)>
With reference to FIGS. 2-4, the sealing apparatus which concerns on Example 1 of this invention is demonstrated. FIG. 2 is a bottom view of the sealing device according to the first embodiment of the present invention. FIG. 3 is a perspective view of the sealing device according to the first embodiment of the present invention viewed from the bottom side. FIG. 4 is a schematic cross-sectional view of the sealing device according to Embodiment 1 of the present invention. 4 is a cross-sectional view taken along line AA in FIG.

  The sealing device 10 according to the present embodiment is generally called a rod packing. The sealing device 10 is made of, for example, a rubber material having a Shore hardness of about Hs70. In this case, for example, it is preferably used in an environment where the maximum pressure of air pressure is about 1 MPa. The sealing device 10 includes seal lips 11 and 12 on the outer peripheral side and the inner peripheral side, respectively.

In addition, a plurality of convex portions 13 are provided on the inner peripheral surface of the sealing device 10 at a predetermined interval (a constant interval in this embodiment) with respect to the circumferential direction. As shown in FIG. 1, the plurality of convex portions 13 extend in the reciprocating movement direction of the piston rod 200 and the cylinder 300 in a state where the sealing device 10 is attached to the pneumatic cylinder 500 (the cylinder 300 thereof). Is provided. Further, the plurality of convex portions 13 are provided so as to extend from the position of the end surface opposite to the sealing region K1 (atmosphere side A) to a position not reaching the tip of the seal lip 12.

<Function of sealing device>
With particular reference to FIG. 5, the function of the sealing device according to the first embodiment of the present invention will be described. FIG. 5 is an explanatory view illustrating the function of the sealing device according to the first embodiment of the present invention. In FIG. 5, in a state where the sealing device according to the present embodiment is mounted on the pneumatic cylinder 500, in a non-pressure state (left side) and a pressurized state (right side), in a schematic cross-sectional view. Show. Further, FIG. 5 shows a cross-sectional view cut at a portion where the above-described convex portion 13 is not provided.

  As illustrated, the sealing device 10 according to the present embodiment is mounted in an annular groove 311 provided on the cylinder 300 side. The outer peripheral seal lip 11 is in close contact with the groove bottom surface of the annular groove 311, and the inner peripheral seal lip 12 is slidably in close contact with the outer peripheral surface of the piston rod 200. Since the plurality of convex portions 13 provided on the inner peripheral surface of the sealing device 10 are provided so as not to reach the tip of the seal lip 12, the tip of the seal lip 12 extends over the entire circumference of the piston rod 200. Closely slidably contacts the outer peripheral surface.

  In the pressurized state, the sealing device 10 is deformed by air pressure, and the entire region from the vicinity of the end of the seal lip 12 to the vicinity of the end surface on the atmosphere side A of the inner peripheral surface of the sealing device 10 is the outer peripheral surface of the piston rod 200. It will be in the state which adhered to.

  However, in the sealing device 10 according to the present embodiment, since the plurality of convex portions 13 are provided on the inner peripheral surface, the portion between the convex portions 13 and the convex portions 13 is on the outer peripheral surface of the piston rod 200. There is no contact, and the gap S is secured. Therefore, compared with the case where the convex part 13 is not provided, the pressing force of the seal lip 12 on the piston rod 200 in the pressurized state is reduced, and the sliding resistance can be reduced.

  Theoretically, sliding resistance = friction coefficient × stressing force.

  Then, the pressing force at the time of pressurization = the pressing force of the seal lip 12 itself + (sliding area × pressure (pressing force)). According to the sealing device 10 according to the present embodiment, since the gap S is secured by providing the plurality of convex portions 13, the sliding area is reduced, and the pressing force during pressurization is reduced.

<Molding of sealing device>
With reference to FIG.6 and FIG.7, shaping | molding by the metal mold | die of the sealing device which concerns on Example 1 of this invention is demonstrated. FIG. 6 is a schematic cross-sectional view showing a state where the sealing device according to the first embodiment of the present invention is molded by a mold. FIG. 7 is a schematic cross-sectional view showing a state when the sealing device according to the first embodiment of the present invention is released.

  The sealing device 10 according to the present embodiment is formed by a first mold 600 and a second mold 700. The first mold 600 forms a portion of the sealing device 10 that extends from the tip of the outer peripheral seal lip 11 to the inner peripheral side, and a portion that extends from the tip of the inner peripheral seal lip 12 to the outer peripheral side. It is configured. And the 2nd metal mold | die 700 is comprised so that other parts (including the part which forms the convex part 13) may be formed.

Further, as shown in FIG. 7, the opening direction of the mold is configured to coincide with the direction in which the convex portion 13 extends (corresponding to the reciprocating movement direction of the piston rod 200 and the cylinder 300). Thereby, in the 2nd metal mold | die 700, the recessed part 701 provided in order to form the convex part 13 becomes a structure extended in the direction which opens a metal mold | die. Therefore, it is not necessary to provide an undercut to form the convex portion 13.

<Excellent points of this embodiment>
A plurality of convex portions 13 are provided on the inner peripheral surface of the sealing device 10 according to the present embodiment. Therefore, the area of the sliding portion relative to the outer peripheral surface of the piston rod 200 on the inner peripheral surface of the sealing device 10 can be reduced, and the sliding resistance can be reduced. Thereby, mechanical loss can be reduced and the lifetime of the sealing device 10 can be improved by suppressing heat generation due to sliding resistance.

  The plurality of convex portions 13 employs a configuration provided so as to extend to a position that does not reach the tip of the seal lip 12. Therefore, since the tip of the seal lip 12 is slidably in contact with the outer peripheral surface of the piston rod 200 over the entire circumference, the sealing performance is not hindered by the plurality of convex portions 13.

  However, in the case of the sealing device 10 according to the present embodiment, it can be suitably used for a pneumatic cylinder, but cannot be suitably used for a hydraulic cylinder from the viewpoint of sealing performance. That is, in the case of the sealing device 10 according to the present embodiment, a plurality of convex portions 13 are provided on the inner peripheral surface at predetermined intervals in the circumferential direction. Therefore, the surface pressure distribution on the outer peripheral surface of the piston rod 200 on the inner peripheral surface of the sealing device 10 varies in the circumferential direction.

  Generally, in a reciprocating seal, when the fluid to be sealed is oil, a mechanism for preventing oil leakage is provided by the difference in film thickness of the oil film between the pushing process and the pulling process. In this case, the variation in the surface pressure distribution in the circumferential direction adversely affects the sealing performance.

  On the other hand, in the reciprocating seal, when the fluid to be sealed is air, it is different from the mechanism in the case of oil. That is, as in the case of the sealing device 10 according to the present embodiment, if the tip of the seal lip 12 is configured to slidably contact the outer peripheral surface of the piston rod 200 over the entire circumference, the air No leakage occurs. That is, even if the surface pressure distribution with respect to the outer peripheral surface of the piston rod 200 on the inner peripheral surface of the sealing device 10 varies in the circumferential direction, a stable sealing property can be obtained.

  Further, in the sealing device 10 according to the present embodiment, the plurality of convex portions 13 are arranged in the reciprocating direction of the piston rod 200 and the cylinder 300 from the position of the end surface on the side opposite to the sealing region K1 (atmosphere side A). Employs a stretchable configuration. Therefore, as described above, the sealing device 10 can be molded without providing the mold with an undercut, and is excellent in releasability.

(Example 2)
FIG. 8 shows a second embodiment of the present invention. In the present embodiment, a configuration in which a plurality of concave portions are provided instead of the plurality of convex portions in the first embodiment is shown. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

FIG. 8 is a perspective view of the sealing device according to the second embodiment of the present invention as viewed from the bottom side. A plurality of recesses 14 are provided on the inner peripheral surface of the sealing device 10a according to the present embodiment at a predetermined interval (a constant interval in the present embodiment) with respect to the circumferential direction. The plurality of recesses 14 are provided so as to extend in the reciprocating direction of the piston rod 200 and the cylinder 300 in a state where the sealing device 10a is mounted on the pneumatic cylinder 500 (the cylinder 300). Further, the plurality of recesses 14 are provided so as to extend from the position of the end surface opposite to the sealing region K1 (atmosphere side A) to a position not reaching the tip of the seal lip 12.

  Thus, the sealing device 10a according to the present embodiment is different from the configuration of the sealing device 10 according to the first embodiment only in that the plurality of convex portions 13 are replaced with the concave portions 14, and the other configurations are as follows. The same as the sealing device 10 according to the first embodiment.

  Also in the sealing device 10a according to the present embodiment, since the plurality of recesses 14 provided on the inner peripheral surface thereof are provided so as not to reach the tip of the seal lip 12, the tip of the seal lip 12 has the entire circumference. In close contact with the outer peripheral surface of the piston rod 200 over the entire area. Further, in the sealing device 10a according to the present embodiment, since the plurality of concave portions 14 are provided on the inner peripheral surface, the concave portion 14 does not adhere to the outer peripheral surface of the piston rod 200, and a gap is ensured. Is done. Therefore, compared with the case where the concave portion 14 is not provided, the pressing force of the seal lip 12 against the piston rod 200 in the pressurized state is reduced, and the sliding resistance can be reduced.

  With the configuration as described above, even in the case of the sealing device 10a according to the present embodiment, the same effect as that of the sealing device 10 according to the first embodiment can be obtained.

FIG. 1 is a partially broken perspective view of a pneumatic cylinder. FIG. 2 is a bottom view of the sealing device according to the first embodiment of the present invention. FIG. 3 is a perspective view of the sealing device according to the first embodiment of the present invention viewed from the bottom side. FIG. 4 is a schematic cross-sectional view of the sealing device according to Embodiment 1 of the present invention. FIG. 5 is an explanatory view illustrating the function of the sealing device according to the first embodiment of the present invention. FIG. 6 is a schematic cross-sectional view showing a state where the sealing device according to the first embodiment of the present invention is molded by a mold. FIG. 7 is a schematic cross-sectional view showing a state when the sealing device according to the first embodiment of the present invention is released. FIG. 8 is a perspective view of the sealing device according to the second embodiment of the present invention as viewed from the bottom side. FIG. 9 is a schematic cross-sectional view of a rod packing according to a conventional example. FIG. 10 is a schematic cross-sectional view of a rod packing that reduces sliding resistance.

Explanation of symbols

10, 10a Sealing device 10X Buffer ring 10Y Dust seal 11, 12 Seal lip 13 Convex part 14 Concave part 100a Piston packing 100b Wear ring 100c Contamination seal 200 Piston rod 300 Cylinder 301, 302 Opening 311 Annular groove 500 Pneumatic cylinder 600 First mold 700 Second mold 701 Concave part K1, K2 Sealing area S Clearance S1, S2 Sealing system

Claims (2)

In a sealing device for sealing an annular gap between a piston rod and a cylinder in a pneumatic cylinder,
A seal lip that extends toward the sealed area where air is sealed and that slidably adheres to the outer peripheral surface of the piston rod,
The inner peripheral surface is provided with a plurality of convex portions extending in the reciprocating direction of the piston rod and the cylinder,
The plurality of convex portions are provided so as to extend from the position of the end surface opposite to the sealing region to a position not reaching the tip of the seal lip. In a sealing device for sealing an annular gap between a piston rod and a cylinder in a pneumatic cylinder,
A seal lip that extends toward the sealed area where air is sealed and that slidably adheres to the outer peripheral surface of the piston rod,
A plurality of recesses extending in the reciprocating direction between the piston rod and the cylinder are provided on the inner peripheral surface,
The plurality of recesses are provided so as to extend from the position of the end surface opposite to the sealing region to a position not reaching the tip of the seal lip.

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