JPH0861510A - Sealing member - Google Patents

Abstract

PURPOSE: To prevent a sealing member from gas leakage resulting from gas permeation and enhance the sealing performance by forming a gas shield layer inside a ring-shaped elastomer to be interposed between two opposing members, and embedding or pinching this gas shield layer in such a condition as across the gas leaking direction. CONSTITUTION: A piston type accumulator is structured so that a sealing member 10 is compressedly interposed between the bottom of a groove 4a formed at the periphery of a piston 4 and the inside surface of a cylindrical shell 1. Thus sealing is generated for a gas chamber 2 in which gas G is encapsulated. The sealing member 10 is accomplished by embedding a gas shield layer 12 formed in a flexible film continuing in the circumferential direction from a metal foil or synthetic resin to shut off the gas permeating inside a ring-shaped elastomer 11 having a circular section across the axis 0 in the non-mounted condition. The synthetic resin film constituting the gas shield layer 12 is formed from polyvinyl alcohol, ethylene vinyl alcohol, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing member for sealing a gas, which is mounted, for example, on the outer peripheral portion of a piston of a piston type accumulator in a compressed state.

[0002]

2. Description of the Related Art In a piston type accumulator, a part of which is shown in FIG. 4, a cylindrical shell 1 and an inner peripheral space of the cylindrical shell 1 which is movably arranged in the inner periphery of the cylindrical shell 1 are provided with a gas G.
A seal member 5 such as an O-ring is interposed between the gas chamber 2 in which is sealed and the piston 4 which is partitioned into the liquid chamber 3 into which the external hydraulic pressure is introduced. The seal member 5 of this type is conventionally made of an elastomer simple substance such as nitrile rubber (NBR), butyl rubber (IIR) or ethylene-propylene rubber (EPDM), which is typically formed in an annular shape, and is movable. It is required to be held in a groove 4a formed on the outer peripheral surface of the piston 4 which is the side, and to be appropriately compressed in the radial direction between the inner peripheral surface of the cylindrical shell 1 which is the stationary side. The sealing function of is given.

[0003]

In the above-mentioned conventional seal member 5, it has been pointed out that the gas G permeates the elastomer material to cause a slight gas leakage over time. There is. FIG. 5 shows the temperature 9
Piston 4 at 0 ° C and gas pressure of 100 kgf / cm ²
It shows the result of the gas leakage test under the stopped condition, and it is considered that the leakage amount is proportional to the gas permeation coefficient which is the gas permeation amount under the standard condition of each elastomer material. Further, particularly in the case of a device using the enclosed gas pressure such as the above-mentioned piston type accumulator, the performance of the seal member 5 changes with time due to such gas leakage.
It is required to improve gas permeation resistance.

The present invention has been made under the circumstances described above, and its technical problem is to improve the gas permeation resistance of the seal member so that the gas permeates through the seal member. This is to prevent gas leaks.

[0005]

The above-mentioned technical problems are as follows.
This can be effectively solved by the present invention. That is, in the seal member according to the present invention, the gas shielding layer is embedded or sandwiched in the annular elastomer interposed in a compressed state between the two members facing each other in a state intersecting the leak direction of the gas to be sealed. It is a thing. Further, in the present invention, more preferably, the gas shielding layer is formed in a state of being inclined with respect to the compression direction of the annular elastomer.

[0006]

The gas shielding layer existing inside the annular elastomer blocks the permeation of the gas to be sealed and is formed so as to intersect with the leak direction of the gas to be sealed, so that the sealing member is formed. The gas permeation area at is reduced. Therefore, it is possible to effectively prevent the gas to be sealed that has penetrated into the annular elastomer from the high-pressure gas atmosphere side from permeating to the opposite side. In this case, if the gas shielding layer has a shape inclined with respect to the compression direction of the annular elastomer, the gas shielding layer is bent and deformed by the shearing force accompanying the compression of the annular elastomer in the mounted state of the seal member. It can be prevented from being received or broken.

[0007]

FIG. 1 shows a first embodiment of the seal member according to the present invention. The seal member 10 of this embodiment is
A synthetic resin film or a metal foil that blocks gas permeation inside an annular elastomer 11 having a circular cross section (hereinafter, simply referred to as a cross section) taken along a plane passing through the axis O in an unloaded state (unmounted state). The gas shielding layer 12, which is a flexible film body continuous in the circumferential direction, is embedded.
That is, the outer appearance of the seal member 10 has a normal O-ring shape, and the synthetic resin film used as the gas shielding layer 12 is, for example, polyvinyl alcohol (PV).
A), ethylene vinyl alcohol (EVA), polyvinylidene chloride (PUdC) and the like are preferable, and when a metal foil is used, for example, one made of aluminum, copper or iron is preferable. In addition, this gas shielding layer 12
Extend in the diametrical direction of the circular cross section of the annular elastomer 11, and the widthwise ends 12a and 12b are the annular elastomer 1
1 has reached near the surface.

As shown in FIG. 2, the above-mentioned seal member 10 is provided, for example, between the groove bottom portion of the groove 4a formed on the outer peripheral surface of the piston 4 of the piston type accumulator and the inner peripheral surface of the tubular shell 1. It is installed in a state of being appropriately compressed in the radial direction,
The gas chamber 2 in which the gas G is sealed is sealed. In the unattached state shown in FIG. 1, the gas shielding layer 12 is in a state of intersecting the leak direction of the gas G to be sealed, that is, the direction parallel to the axis O at an angle θ, and in the compressed attached state shown in FIG. It is formed so as to form an angle θ ₁ .

The gas shielding area S by the gas shielding layer 12 (the projected area of the gas shielding layer 12 in the axial direction) becomes maximum when θ = 90 °, but in this case, the groove bottom of the groove 4a of the piston 4 and Since the gas shielding layer 12 is largely deformed in the radial direction when it is mounted in a compressed state between the inner peripheral surface of the cylindrical shell 1 that is radially opposed to the gas shielding layer 1
2 has a shape inclined appropriately with respect to the compression direction, that is, the radial direction, and preferably θ is 85 ° or less. Further, the smaller the angle θ of the gas shielding layer 12, the larger the area ratio of the gas permeation area (S ₀ −S) to the axial projected area S ₀ of the seal member 10, so that θ is the above area ratio. The area ratio is 30 ° or more, which is 50% or less, and preferably 60 ° or more, which is 14% or less. Therefore, the magnitude of θ is 30 ° ≦ θ <85 °, preferably 60 ° ≦ θ ≦
It is set at 85 °.

Therefore, according to this embodiment, since the gas permeation area in the seal member 10 becomes small, the sealing target gas G permeating from the gas chamber 2 into the annular elastomer 11 permeates to the liquid chamber 3 side. The leakage can be effectively suppressed. Further, for this reason, it is possible to effectively prevent the performance of the accumulator from changing with time due to the reduction of the amount of the enclosed gas in the gas chamber 2.

FIG. 3 shows another embodiment of the seal member 10 according to the present invention in an unmounted state, among which (a)-
(D) is similar to the first embodiment of FIG. 1 in that the seal member 10 has an O-ring appearance. It should be noted that in each of the embodiments shown in FIG. 3, the upper part of the drawing is mounted on the gas side to be sealed.

First, as shown in FIG. 3A, an annular elastomer 11 having a semicircular cross section is integrally bonded to both surfaces of a gas shielding layer 12 which is a flexible film body made of a synthetic resin film or a metal foil and continuous in the circumferential direction. The gas-shielding layer 12 is formed as shown in FIG.
Similar to the first embodiment, the shape intersects the direction parallel to the axis O at an angle θ, and the widthwise ends 12a and 12b are exposed on the surface of the annular elastomer 11. FIG. 3 (b) shows a cross-sectional shape of the gas shielding layer 12 which is substantially S-shaped with both widthwise ends 12a and 12b bent in opposite directions in the substantially axial direction. ) Indicates that the cross-sectional shape of the gas shielding layer 12 is a curved shape that is concave with respect to the gas to be sealed side (upper side in the drawing), and FIG. 3D illustrates the cross-sectional shape of the gas shielding layer 12. , Which is a concave shape with respect to the gas side to be sealed (upper side in the figure).

Further, FIGS. 3 (e) to 3 (g) show the embodiment of the present invention with respect to the seal member 10 having an appearance other than the O-ring.

That is, FIG. 3E shows the annular elastomer 1.
The outer peripheral surface 11a has a semi-circular convex shape and the inner peripheral surface 11b has a substantially D-shape extending in a direction parallel to the axis O. The layer 12 is embedded in a state where it intersects with a direction parallel to the axis O at an angle θ. In FIG. 3 (f), the sectional shape of the annular elastomer 11 is such that the outer peripheral surface 11 a has the axis O.
The gas shielding layer 12 extends in a direction parallel to the inner peripheral surface 11b and has a semi-arcuate convex shape, that is, inside the annular elastomer 11 having a D-shaped cross section opposite to that of FIG. Is embedded in a state of intersecting with the axis O at an angle θ. Further, FIG. 3 (g) shows that the gas shield layer 12 is provided inside the annular elastomer 11 having a substantially square cross section. It is embedded in a state intersecting with O at an angle θ.

The seal member 10 of the present invention is not limited to the sealing means for the piston type accumulator, and other than the illustrated embodiments, for example, FIG.
Each of the gas shielding layers 12 in (e) to (g) is shown in FIG.
Various modifications are possible, such as the shapes shown in (a) to (d). Further, when the seal member 10 is mounted between members that face each other in the axial direction, the leak direction of the gas to be sealed is the radial direction. In this case, therefore, the gas shielding layer 12 moves in the radial direction. It is provided in the annular elastomer 11 in a state of intersecting with the angle θ.

[0016]

According to the seal member of the present invention, the gas shielding layer provided inside the annular elastomer blocks the permeation of the gas to be sealed which has permeated the annular elastomer, and reduces the gas permeation area of the annular elastomer. Further, it is possible to effectively prevent the time-dependent gas leakage due to the gas permeation of the seal member and improve the sealing performance.

[Brief description of drawings]

FIG. 1 is a half cross-sectional view of an unmounted state, showing a first embodiment of a seal member according to the present invention by cutting along a plane passing through an axis.

FIG. 2 is a half cross-sectional view of a mounted state in which the above embodiment is cut along a plane passing through an axis.

FIG. 3 is a half sectional view in an unmounted state, showing another embodiment of the seal member according to the present invention by cutting along a plane passing through an axis.

FIG. 4 is a half cross-sectional view of a mounted state showing an example of a conventional seal member by cutting along a plane passing through an axis.

FIG. 5 is an explanatory diagram showing a result of a gas leakage test performed on the conventional example.

[Explanation of symbols]

 1 Cylindrical Shell 2 Gas Chamber 3 Liquid Chamber 4 Piston 4a Groove 10 Sealing Member 11 Annular Elastomer 11a Outer Surface 11b Inner Surface 12 Gas Shielding Layer 12a, 12b Width Direction Both Ends G Gas to be Sealed

Claims (2)

[Claims] 1. An annular elastomer (11) interposed in a compressed state between two members facing each other, and a state in which the annular elastomer (11) intersects the leak direction of the gas (G) to be sealed inside the annular elastomer (11). A sealing member comprising a gas shielding layer (12) embedded or sandwiched. 2. The gas barrier layer (12) according to claim 1, wherein the gas shielding layer (12) comprises the annular elastomer (1).
A seal member, which is inclined with respect to the compression direction of 1).