JP3488951B2 - Seal structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure suitable for high-pressure gas piping and the like, and more particularly to an improvement of the seal structure for facilitating the discovery of leaks.

[0002]

2. Description of the Related Art Generally, as described in Japanese Patent Laid-Open No. 2000-161555, a rubber O-ring, a flat packing, a metal seal, etc. are provided on a joint surface of a device to which pressure is applied. It is provided, and its elasticity provides a sealing property. Moreover, in order to improve the sealing property,
For example, as disclosed in Japanese Patent Laid-Open No. 10-213228, there has been proposed one in which rubber seals having different swelling properties are arranged to improve the surface pressure on the sealing surface.

By the way, it is required that a leak check in a high-pressure system mounted on a moving body such as a vehicle is appropriately performed as a part of inspection and maintenance. In particular, in fuel cell vehicles that use high-pressure hydrogen gas, in addition to requiring more reliable sealability in consideration of the characteristics and pressure of the working gas, maintenance of the seal part to maintain high sealability is also required. The inspection must be done properly.

However, in the conventional sealing device, even if a leak occurs, it is difficult to quickly identify the location,
In order to identify it, it is necessary to perform a troublesome leak test such as applying soap water to the seal portion while supplying the working fluid again. The present invention has been made in view of such conventional problems, and provides a seal structure capable of easily identifying a leak location without adding a special device for leak detection during inspection. The purpose is to do.

[0005]

A first invention is a pipe joint.
Of the high pressure side and the low pressure side.
Forming a bonding surface of the annular defining a Kangaibu, the bonding surface
In the annular groove formed on the
Fit the low-pressure side sealing material. The low-pressure side sealing material,
With permeation resistance of the high-pressure side to the fluid to form at a lower material than the high-pressure side seal member, outside the low-pressure side seal member
Outer circumferential region of the low-pressure side seal member a gap that allows swelling to the side
To increase the amount of change in the sealing material due to the swelling in the circumferential direction.
Try to be big .

In a second aspect of the invention, the high pressure side sealing material is H
-NBR Nitrile Butadiene rubber or the like made of a rubber material having a high permeation resistance to hydrogen gas.

In a third aspect of the invention, the high-pressure side sealing material is composed of a metal seal.

According to a fourth aspect of the invention, the low-pressure side sealing material is made of a rubber material such as silicone rubber having a low permeation resistance to hydrogen gas.

[0009]

[0010]

A fifth aspect of the present invention is to seal the high pressure side on the joint surface.
Material and the low-pressure side sealing material individually form an annular groove, and the depth of the outer annular groove into which the low-pressure side sealing material fits is greater than the depth of the inner annular groove into which the high-pressure side sealing material fits. I made it shallow.

According to a sixth aspect of the present invention, the cross-sectional shape of the low-pressure side sealing material is such that it covers the outer peripheral portion of the high-pressure side sealing material, and these sealing materials are housed in a common annular groove formed on the joint surface. It was configured to do.

In a seventh aspect of the invention, the low-pressure side sealing material is arranged eccentrically with respect to the high-pressure side sealing material.

In an eighth aspect of the invention, the radial thickness of the low-pressure side sealing material is partially reduced. The seal structure according to claim 5.

According to a ninth aspect of the present invention , a recess is formed on the inner peripheral surface of the low-pressure side sealing material so as to face the outer peripheral surface of the high-pressure side sealing material.

[0016]

According to each of the following inventions,
The fluid pressure on the high pressure side can usually be sealed by the high pressure side sealing material. However, if a leak occurs in the high-pressure side sealing material, the low-pressure side sealing material was formed due to the fluid leakage because the low-pressure side sealing material was formed of a material having relatively low permeation resistance to the fluid. The swelling portion swells to the outside and the swelling portion enters into the gap formed in the outer peripheral area between the joint surfaces. At this time, the gap is sealed by swelling.
Since the amount of material change is increased in the circumferential direction,
Side low pressure side sealing material swells to the outer peripheral side when a leak occurs
Can be detected early . For this reason, it is possible to easily detect the occurrence of leakage by observing from the outside, and therefore it is possible to detect the leakage at an early stage and appropriately manage the seal portion.

When the fluid to be sealed is a gas having a small molecular weight such as hydrogen gas, it has a high permeability to the sealing material such as rubber, and therefore, the leakage is visually confirmed based on the swelling due to the depressurizing foaming phenomenon of the sealing material. Will be easier. When sealing hydrogen gas, as shown in the second to fourth inventions, the high pressure side sealing material is a rubber material such as H-NBR nitrile butadiene rubber having a high permeation resistance to hydrogen gas. Alternatively, a metal seal can be used as the low-pressure side seal material, and a rubber material such as silicone rubber having low resistance to permeation of hydrogen gas can be applied.

As shown as the fifth aspect of the invention, an annular groove in which the high-pressure side sealing material and the low-pressure side sealing material are respectively fitted is formed in the joint surface of the pipe joint, and an outer annular shape in which the low-pressure side sealing material is fitted. By making the depth of the groove shallower than the inner annular groove into which the high-pressure side sealing material fits, it is possible to increase the amount of change in the outer circumferential direction when the low-pressure side sealing material swells.

The pipe joint sealing structure is as follows:
As shown in the invention of No. 6 , the cross-sectional shape of the low-pressure side sealing material is set to cover the outer peripheral portion of the high-pressure side sealing material, and each of these sealing materials is housed in a common annular groove formed on the joint surface. It is possible to adopt a configuration, which improves the workability of assembling the seal.

Further, as shown as the seventh invention, the annular low-pressure-side sealing material is arranged eccentrically with respect to the high-pressure-side sealing material, or as shown in the eighth invention, the diameter of the low-pressure-side sealing material. By partially thinning the wall thickness in the direction,
When the low-pressure side sealing material swells due to leakage, the space between the inner and outer sealing materials is narrow or the low-pressure side sealing material is thin.
Since a larger deformation occurs in the stomach content, to identify the seal deformation locations in the joint outer peripheral portion during the leak occurs in locations such as the angle of visual observation is limited, making it easier to discover the leakage point Is possible.

Further, as shown as the ninth aspect of the invention, by forming a concave portion on the inner peripheral surface of the low pressure side sealing material so as to face the outer peripheral surface of the high pressure side sealing material, the high pressure side of the low pressure side sealing material is formed. Since the surface area of the portion facing the side is increased and the contact area with the fluid from the high pressure side is increased accordingly, the deformation amount of the low pressure side sealing material due to the swelling at the time of fluid permeation can be increased in the circumferential direction.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a high-pressure hydrogen gas pipe joint will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a high-pressure pipe seal structure capable of determining a leak in a fuel cell vehicle. In the figure, T is a high-pressure container that stores pressurized hydrogen gas, F is a fuel cell stack, P is a piping system that connects the container T and the stack F, and some joints S are provided in the middle thereof. ing. As shown in FIG. 2, the pipe joint S is composed of the gas pipe 1, the joint 2, the seal 3 and the like.
The seal portion 3 includes two joint elements 2A and 2B that are fastened to each other via fasteners (not shown) and their end faces 4 facing each other.
Two inner and outer O-rings 3a, 3b sandwiched between A and 4B
It is composed by. Each of the O-rings 3a and 3b has a double seal structure made of materials having different permeability to hydrogen gas. That is, a rubber material having a high gas permeation resistance to hydrogen gas, such as H-NBR nitrile butadiene rubber, is used for the O-ring 3a on the inner peripheral side (high pressure side) that is directly exposed to hydrogen gas. On the other hand, for the O-ring 3b on the outer peripheral side (low pressure side) adjacent to the inner peripheral portion, a rubber material such as silicone rubber having low gas permeation resistance is used.

In the above structure, when the high pressure pipe leaks from the inner peripheral O-ring 3a of the joint seal portion 3, pressure is applied to the outer peripheral O-ring 3b, and the inner peripheral surface of the outer peripheral O-ring 3b moves inward. Hydrogen gas invades. Since the outer circumference of the outer O-ring portion 3b is at atmospheric pressure, the outer O-ring 3b
All or part of the product undergoes a depressurization foaming phenomenon and swells. The depressurized foaming phenomenon is a phenomenon in which the pressurized hydrogen that has penetrated into the rubber is bubbled inside the rubber to increase its volume when it is exposed to about atmospheric pressure, which causes the apparent volume of the rubber material to increase and swell. Is. When this depressurized foaming phenomenon occurs, a part of the outer peripheral O-ring 3b protrudes from the gap G between the joint surfaces 4A and 4B to the outside where the pressure is low due to the swelling of the leaked part, so that the leaked part can be easily visually observed. Can be specified. FIGS. 3 and 5 show the appearance of the joint and the details of the seal before the leak occurs, and FIGS. 4 and 6 show the appearance of the joint and the details of the seal when the leak occurs. When this occurs, the O-ring 3b on the outer peripheral side swells and protrudes to the outside, so that the leakage can be easily found. The swelling of the O-ring 3b on the outer circumference may occur altogether or partially depending on the situation of leakage in the O-ring 3a on the inner circumference.

7 and 8 show a second embodiment of the present invention. The basic sealing structure is the same as that of the first embodiment, but in this embodiment, the entire circumference is formed so as to face the inner peripheral surface of the outer peripheral O-ring 3b and the outer peripheral surface of the inner peripheral O-ring 3a. The recess 5 is formed partially or partially. By providing the concave portion 5 in this way, the surface area of the portion of the outer O-ring 3b facing the high pressure side increases and the contact area with the leaked hydrogen increases accordingly, so that the outer O-ring 3b due to swelling during gas permeation. Can be increased in the circumferential direction, that is, leak detection can be made easier.

9 to 11 show a third embodiment of the present invention. In addition to the configuration of the first embodiment, this is provided with annular grooves 6a and 6b for fitting the inner and outer O-rings 3a and 3b on one joint surface 4B, and as shown in FIG. The depth DO of the outer annular groove 6b is formed shallower than the depth DI of the inner annular groove 6a. By reducing the fitting depth of the outer O-ring 3b in this way,
By increasing the degree of freedom of displacement of the O-ring 3b in the circumferential direction,
The amount of change due to swelling during gas permeation can be increased in the circumferential direction.

12 to 14 show a fourth embodiment of the present invention. This makes the cross-sectional shape of the outer O-ring portion 3b substantially cover the outer half of the inner O-ring 3a, and as shown in FIG. 14, forms the annular groove 6 into which the O-ring is fitted. The commonality, that is, the configuration in which the two O-rings 3a and 3b are assembled with the single annular groove 6 improves the workability of the assembly.

FIGS. 15 and 16 show a fifth embodiment of the present invention. In this embodiment, as shown in FIG.
The ring 3b is eccentrically arranged with respect to the inner peripheral O-ring 3a. Further, in this embodiment, the inner O-ring 3a
The outermost O-ring 3b is made thinner in the radial direction at the portion closest to. By eccentrically arranging the outer O-ring 3b in this way and further arranging it with a partial thinning,
If leakage from the O-ring 3a occurs, the ring 3a-
The deformation of the outer peripheral O-ring 3b increases from a thin portion having a short distance between 3b, and it becomes possible to easily identify a leak location from the outside. Particularly, when an angle that is difficult to see is generated on the outer circumference of the joint portion due to the layout of the pipe or the position of the joint portion, the eccentric portion of the O-ring is oriented in the visible direction as in this embodiment.
Finding leaks is easy and reliable.

FIG. 17 shows a sixth embodiment of the present invention. This is the different from the embodiments in <br/> that provided a metal seal 7 as the inner peripheral side sealing member. In the figure, 71 is a sleeve of a metal seal, 72 is a tightening surface thereof, and 73 is a tightening metal fitting that deforms along the tightening surface 72 while tightening and closely adheres to exhibit a sealing property. As described above, as the sealing material on the inner peripheral side, various materials can be applied without being limited to the O-ring as long as the material has high hydrogen permeability or hydrogen sealing property. In particular, the metal seal 7 has an excellent sealing property against hydrogen gas as compared with rubber or resin, and has an advantage of exhibiting stable sealing property without being deteriorated or deformed by the fluid to be sealed.

Although each of the above-mentioned embodiments has exemplified the sealing of the hydrogen gas pipe in the fuel cell system, the present invention is not limited to this, and can be applied to a pipe using helium as a fluid, for example. Can also be applied.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fuel cell piping system according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a joint portion of the first embodiment.

FIG. 3 is an explanatory view of the outer appearance of the joint of the first embodiment before the occurrence of leakage.

FIG. 4 is an explanatory diagram of a joint appearance of the first embodiment when a leak occurs.

FIG. 5 is a detailed cross-sectional view of the essential parts of the joint of the first embodiment before a leak occurs.

FIG. 6 is a detailed cross-sectional view of the essential parts of the joint when a leak occurs in the first embodiment.

FIG. 7 is a detailed cross-sectional view of a main part of the joint before the occurrence of leakage according to the second embodiment of the present invention.

FIG. 8 is a detailed cross-sectional view of an essential part of the joint when a leak occurs in the second embodiment.

FIG. 9 is a detailed cross-sectional view of the essential parts of the joint before the occurrence of leakage according to the third embodiment of the present invention.

FIG. 10 is a detailed cross-sectional view of the essential parts of the joint when a leak occurs in the third embodiment.

FIG. 11 is a detailed cross-sectional view of an essential part for explaining the shape of the annular groove of the third embodiment.

FIG. 12 is a detailed cross-sectional view of an essential part of the joint before the occurrence of leakage according to the fourth embodiment of the present invention.

FIG. 13 is a detailed cross-sectional view of the essential parts of the joint when a leak occurs in the fourth embodiment.

FIG. 14 is a detailed cross-sectional view of an essential part showing the annular groove shape of the fourth embodiment.

FIG. 15 is an explanatory diagram showing a state of the O-ring before the occurrence of leakage according to the fifth embodiment of the present invention.

FIG. 16 is an explanatory view showing a state of an O-ring when a leak occurs in the fifth embodiment.

FIG. 17 is a detailed cross-sectional view of essential parts of the joint when a leakage occurs according to the sixth embodiment of the present invention.

[Explanation of symbols]

1 piping 2 joint 2A, 2B joint element 3 Seal part 3a Inner O-ring (high-pressure side sealing material) 3b Outer O-ring (low pressure side seal material) 4A, 4B joint surface 5 recess 6,6A, 6b Annular groove 7 Metal seal

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16J 15/10 F16L 15/04 F16L 23/16

Claims (9)

(57) [Claims] 1. A pipe having a high-pressure side on opposite end faces of a pipe joint.
An annular joint surface that defines the inside and the outside of the low-pressure side pipe
And the annular groove formed in the joining surface, the annular high pressure side
A sealing material and a low-pressure side sealing material are fitted together , and the low-pressure side sealing material is formed of a material having a resistance to permeation of a high-pressure side fluid lower than that of the high-pressure side sealing material, and the outside of the low-pressure side sealing material. said a gap to allow the swelling to
Provided in the outer peripheral area of the low-pressure side sealing material, and sealing by the swell
The feature is that the amount of material change is increased in the circumferential direction.
Seal structure. 2. The seal structure according to claim 1, wherein the high-pressure side seal material is made of a rubber material having high resistance to hydrogen gas such as HNBR nitrile butadiene rubber. 3. The seal structure according to claim 1, wherein the high-pressure side sealing material is a metal seal. 4. The seal structure according to claim 1, wherein the low-pressure side seal material is made of a rubber material such as silicone rubber having low resistance to permeation of hydrogen gas. 5. An annular groove in which the high-pressure side sealing material and the low-pressure side sealing material are individually fitted is formed on the joint surface, and the depth of the outer annular groove in which the low-pressure side sealing material is fitted is set to the high pressure side. The shallower than the inner annular groove into which the sealing material fits.
Seal structure described in. 6. The cross-sectional shape of the low-pressure side sealing material is configured to cover the outer peripheral portion of the high-pressure side sealing material, and these sealing materials are housed in a common annular groove formed on the joint surface. The seal structure according to claim 1. 7. The seal structure according to claim 1, wherein the low-pressure side seal material is arranged eccentrically with respect to the high-pressure side seal material. 8. The seal structure according to claim 1, wherein a radial thickness of the low-pressure side sealing material is partially reduced. 9. The seal structure according to claim 1, wherein a concave portion is formed on an inner peripheral surface of the low pressure side sealing material so as to face an outer peripheral surface of the high pressure side sealing material.