JP2002228003A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sealing structure to easily find out leakage of high-pressure gaseous hydrogen at a pipe joint. SOLUTION: Between joint faces 4A, 4B defining a high pressure side and a low pressure side, O-rings 3a, 3b are sandwiched so that the O-ring 3a is positioned on the high pressure side and the O-ring 3b is positioned on the low pressure side. The low pressure side O-ring 3b is formed of a material having lower permeability resistance than the O-ring 3a, against gaseous hydrogen from the high pressure side. A gap G is disposed between the joint faces to allow swelling of the low pressure side O-ring 3b toward the low pressure side.

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 a high-pressure gas pipe or the like, and more particularly, to an improvement in a seal structure for facilitating detection of a leak.

[0002]

2. Description of the Related Art Generally, rubber O-rings, flat packings, metal seals, and the like are provided on the joint surfaces of equipment under pressure as disclosed in Japanese Patent Application Laid-Open No. 2000-161555. The seal is provided by the elasticity. Also, in order to improve the sealing property,
For example, as disclosed in Japanese Patent Application Laid-Open No. H10-213228, there has been proposed a structure in which rubber seals having different swelling performances are arranged to improve the surface pressure on the seal surface.

Meanwhile, it is required that a leak check in a high-pressure system mounted on a moving body such as a vehicle be appropriately performed as a part of inspection and maintenance. In particular, in a fuel cell vehicle using high-pressure hydrogen gas, in addition to the need for more reliable sealing in consideration of the characteristics and pressure of the working gas, maintenance of the sealing portion for maintaining and maintaining high sealing is required. Inspections must be performed properly.

[0004] However, in the conventional sealing device, even if a leak occurs, it is difficult to quickly identify the location.
For this purpose, it is necessary to perform a troublesome leak test such as applying a soapy water to the seal portion while supplying the working fluid again. The present invention has been made in view of such a conventional problem, and provides a seal structure capable of easily discriminating a leak portion without adding a special device for leak detection at the time of inspection. It is intended to be.

[0005]

According to a first aspect of the present invention, a high-pressure side sealing material is positioned between a joining surface defining a high-pressure side and a low-pressure side so as to be positioned on a high-pressure side. The low-pressure side seal material is sandwiched between the low-pressure side seal material and the low-pressure side seal material is formed of a material having lower permeability than the high-pressure side seal material with respect to the high-pressure side fluid. Allowable gaps were provided between the joining surfaces.

According to a second aspect of the present invention, the high-pressure side sealing material is H
-A rubber material having high permeability resistance to hydrogen gas such as NBR nitrile butadiene rubber or the like.

In a third aspect of the present invention, the high-pressure side sealing member is formed of a metal seal.

In a fourth aspect of the present invention, the low-pressure side sealing material is made of a rubber material made of silicone rubber or the like, which has low resistance to hydrogen gas.

According to a fifth aspect of the present invention, the joint surface is formed in an annular shape on the opposite end face of the pipe joint, and annular high-pressure side seal material and low-pressure side seal material are respectively provided on an inner peripheral portion and an outer peripheral portion of the annular joint surface. It was arranged.

In a sixth aspect based on the fifth aspect,
The gap is provided in the outer peripheral area of the low-pressure side sealing material so that the amount of change of the sealing material due to swelling is increased in the circumferential direction.

[0011] In a seventh aspect based on the fifth aspect,
An annular groove in which the high-pressure-side sealing material and the low-pressure-side sealing material respectively fit is formed on the joint surface, and the depth of the outer annular groove in which the low-pressure-side sealing material fits is adjusted to the inside in which the high-pressure-side sealing material fits. Shallower than the annular groove.

[0012] In an eighth aspect based on the fifth aspect,
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 each of the sealing materials is housed in a common annular groove formed on the joint surface.

According to a ninth aspect, in the fifth aspect,
The low-pressure side sealing material was disposed eccentrically with respect to the high-pressure side sealing material.

According to a tenth aspect, in the fifth aspect, the radial thickness of the low-pressure side sealing material is partially reduced. The seal structure according to claim 5.

In an eleventh aspect based on the fifth aspect, a concave portion is formed on the inner peripheral surface of the low-pressure side seal member so as to face the outer peripheral surface of the high-pressure side seal member.

[0016]

According to each of the following inventions,
Normally, the high-pressure side fluid pressure can be sealed with a high-pressure side sealing material. However, if leakage occurs at the high-pressure side seal material, the low-pressure side seal material is formed of a material having relatively low permeation resistance to the fluid. It swells and the swollen portion enters the gap between the joining surfaces. For this reason,
The occurrence of a leak can be easily found by observation from the outside, so that the leak can be found early and the management of the seal portion can be performed accurately.

When the fluid to be sealed is a gas having a small molecular weight such as hydrogen gas, since the permeability to the sealing material such as rubber is high, the leakage is visually confirmed particularly based on the swelling due to the depressurizing foaming phenomenon of the sealing material. Becomes easier. In the case where hydrogen gas is sealed, as described in the second to fourth inventions, a rubber material having high resistance to hydrogen gas such as H-NBR nitrile butadiene rubber is used as the high-pressure side sealing material. Alternatively, as the metal seal, a rubber material having low resistance to hydrogen gas, such as silicone rubber, can be used as the low-pressure side seal material.

As shown in the fifth aspect of the present invention, the pipe joint portion has a structure in which annular high-pressure side sealing material and low-pressure side sealing material are disposed on the inner peripheral portion and the outer peripheral portion of the opposed annular joint surface, respectively. In this case, the gap between the joining surfaces is provided in the outer peripheral region of the low-pressure side sealing material to increase the amount of change in the sealing material due to swelling in the circumferential direction, particularly as shown in the sixth invention. With this configuration, it is possible to early detect that the outer low-pressure side sealing material swells to the outer peripheral side when a leak occurs. Alternatively, as described as the seventh invention, an annular groove in which the high-pressure side seal material and the low-pressure side seal material are fitted respectively is formed on the joint surface of the pipe joint, and an outer annular groove in which the low-pressure side seal material fits. Is made shallower than the inner annular groove into which the high-pressure side sealing material is fitted, so that the amount of change in the outer peripheral direction when the low-pressure side sealing material swells can be increased.

Further, as for the sealing structure of the pipe joint, as shown in the eighth invention, the cross-sectional shape of the low-pressure side sealing material is formed to cover the outer peripheral portion of the high-pressure side sealing material, and each of these sealing materials is formed. Can be accommodated in a common annular groove formed on the joint surface, whereby the workability of assembling the seal is improved.

Further, as shown in the ninth invention, the annular low pressure side sealing material is disposed eccentrically with respect to the high pressure side sealing material, or as shown in the tenth invention, the diameter of the low pressure side sealing material is reduced. When the low-pressure side seal material swells due to leakage by partially reducing the thickness in the direction, the gap between the inner and outer seal materials is narrower, or the low-pressure side seal material is thinner and larger in the portion. Since deformation occurs, it is possible to specify a seal deformation portion on the outer peripheral portion of the joint when a leak occurs at a place where a visual angle is limited, and to easily find the leak portion.

Also, as shown in the eleventh 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 surface area of the portion facing the high-pressure side of the low-pressure side sealing material increases, and accordingly, from the high-pressure side Since the contact area with the fluid increases, the amount of deformation of the low-pressure-side sealing material due to swelling when the fluid permeates can be increased in the circumferential direction.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 leakage in a fuel cell vehicle. In the figure, T is a high-pressure container storing pressurized hydrogen gas, F is a fuel cell stack, P is a piping system connecting between the container T and the stack F, and several joints S are provided in the middle thereof. ing. As shown in FIG. 2, the pipe joint section S includes a gas pipe 1, a joint section 2, a seal section 3, and the like.
The seal portion 3 includes two joint elements 2A and 2B that are fastened to each other via a fastener (not shown) and an opposing end surface 4 thereof.
Two O-rings 3a, 3b sandwiched between A and 4B
It consists of. 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 high gas permeability with respect 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) which directly touches hydrogen gas. On the other hand, for the O-ring 3b on the outer peripheral side (low pressure side) adjacent to the inner peripheral part, a rubber material made of silicone rubber having low gas permeability resistance is used.

In the above configuration, when a high-pressure portion 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 is moved from the inner peripheral surface to the inside. Hydrogen gas enters. Since the outer circumference of the outer O-ring 3b is at atmospheric pressure, the outer O-ring 3b
All or a part of the swelling causes a depressurization foaming phenomenon. Depressurized foaming is a phenomenon in which pressurized hydrogen that has penetrated into rubber is bubbled inside the rubber when it touches about atmospheric pressure, increasing the volume, thereby increasing the apparent volume of the rubber material and swelling. It is. When this depressurization foaming phenomenon occurs, a part of the outer peripheral side O-ring 3b protrudes from the gap G between the joining surfaces 4A and 4B to the outside where the pressure is low due to swelling of the leaked part, so that the leaked part can be easily visually checked. Can be identified. 3 and 5 show the appearance of the joint and the details of the seal before leakage occurs, and FIGS. 4 and 6 show the appearance of the joint and details of the seal before leakage occurs, respectively. When this occurs, the outer O-ring 3b swells and protrudes outward, so that leakage can be easily found. The swelling of the outer O-ring 3b may occur over the entire circumference or may occur partially depending on the state of leakage at the inner O-ring 3a.

FIGS. 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 periphery of the inner peripheral surface of the outer O-ring 3b is opposed to the outer peripheral surface of the inner O-ring 3a. The recess 5 is formed in or partially. By providing the concave portion 5 in this manner, the surface area of the portion of the outer peripheral side O-ring 3b facing the high pressure side increases, and the contact area with the leaked hydrogen increases accordingly, so that the outer peripheral O-ring 3b due to swelling during gas permeation. Can be increased in the circumferential direction, that is, leak detection can be made easier.

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

FIGS. 12 to 14 show a fourth embodiment of the present invention. In this case, the cross-sectional shape of the outer O-ring portion 3b is formed so as to substantially cover the outer half circumference of the inner O-ring 3a, and the annular groove 6 into which the O-ring is fitted as shown in FIG. By making the O-rings 3a, 3b to be assembled with one annular groove 6, the assembling workability is improved.

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. In this embodiment, the inner peripheral O-ring 3a
The radial thickness of the outer O-ring 3b is reduced at the portion closest to the above. By eccentrically arranging the outer O-ring 3b and further arranging the O-ring 3b partially thinner in this way, the inner O-ring 3b
When leakage from the O-ring 3a occurs, the ring 3a-
The deformation of the outer peripheral side O-ring 3b is increased from a thin portion where the distance between the outer rings 3b is short, so that it is possible to easily identify a leak location from the outside. In particular, in the case where an angle that is difficult to see is generated on the outer periphery of the joint due to the layout of the pipe and the position of the joint, by arranging the eccentric part of the O-ring in a direction that can be seen as in this embodiment,
Leaks are easily and reliably found.

FIG. 17 shows a sixth embodiment of the present invention.
This differs from the above-described embodiments in a store where a metal seal 7 is provided as an inner peripheral side seal material. In the drawing, reference numeral 71 denotes a sleeve of a metal seal, 72 denotes a tightening surface thereof, and 73 denotes a tightening fitting which deforms along the tightening surface 72 during tightening to exhibit tight sealing properties. As described above, the sealing material on the inner peripheral side is not limited to the O-ring as long as it has a high hydrogen permeability or hydrogen sealing property, and various materials can be applied. 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 a stable sealing property without being deteriorated or deformed by a sealing fluid.

In each of the embodiments described above, the seal of the hydrogen gas pipe in the fuel cell system is taken as an example. However, the present invention is not limited to this, and is applicable to a pipe using helium as a fluid. Can also be applied.

[Brief description of the 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 according to the first embodiment.

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

FIG. 4 is an explanatory diagram of the appearance of the joint when leakage occurs in the first embodiment.

FIG. 5 is a detailed cross-sectional view of a main part of the joint before leakage of the first embodiment.

FIG. 6 is a detailed cross-sectional view of main parts of the joint when leakage occurs according to the first embodiment.

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

FIG. 8 is a detailed cross-sectional view of a main part of the joint when leakage occurs according to the second embodiment.

FIG. 9 is a detailed cross-sectional view of a main part of a joint before leakage occurs according to a third embodiment of the present invention.

FIG. 10 is a detailed cross-sectional view of a main part of the joint when leakage occurs according to the third embodiment.

FIG. 11 is a detailed cross-sectional view of a main part for describing an annular groove shape according to the third embodiment.

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

FIG. 13 is a detailed cross-sectional view of a main part of the joint when leakage occurs according to the fourth embodiment.

FIG. 14 is a detailed sectional view of a main part showing an annular groove shape according to the fourth embodiment.

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

FIG. 16 is an explanatory diagram showing a state of an O-ring at the time of occurrence of leakage according to the fifth embodiment.

FIG. 17 is a detailed sectional view of a main part of a joint when leakage occurs according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piping 2 Joint part 2A, 2B Joint element 3 Seal part 3a Inner peripheral side O-ring (high-pressure side sealing material) 3b Outer peripheral side O-ring (low-pressure side sealing material) 4A, 4B Joining surface 5 Depression 6,6A, 6b Annular groove 7 Metal seal

Claims (11)

[Claims] 1. The method according to claim 1, wherein the high pressure side and the low pressure side are joined between joining surfaces.
The high-pressure side sealing material is sandwiched between the high-pressure side sealing material and the low-pressure side sealing material so as to be located on the low-pressure side, and the low-pressure side sealing material has a higher permeability to the high-pressure side fluid than the high-pressure side sealing material. And a gap formed between the joining surfaces to allow the low-pressure side sealing material to swell toward the low-pressure side. 2. The sealing structure according to claim 1, wherein the high-pressure side sealing material is made of a rubber material having high resistance to hydrogen gas such as H-NBR nitrile butadiene rubber. 3. The seal structure according to claim 1, wherein the high-pressure side sealing material is formed of a metal seal. 4. The seal structure according to claim 1, wherein said low-pressure side sealing material is made of a rubber material having low resistance to hydrogen gas, such as silicone rubber. 5. The seal according to claim 5, wherein said joint surface is formed in an annular shape on the opposite end face of the pipe joint, and annular high-pressure side seal material and low-pressure side seal material are respectively disposed on an inner peripheral portion and an outer peripheral portion of said annular joint surface. The seal structure according to any one of claims 1 to 4. 6. The seal structure according to claim 5, wherein the gap is provided in an outer peripheral region of the low-pressure side seal material, and a change amount of the seal material due to swelling is increased in a circumferential direction. 7. An annular groove in which the high-pressure-side sealing material and the low-pressure-side sealing material are fitted respectively on the joint surface, and the depth of the outer annular groove in which the low-pressure-side sealing material fits is determined by adjusting the depth of the high-pressure-side sealing material. 6. The seal structure according to claim 5, wherein the depth of the seal structure is smaller than that of the inner annular groove into which the groove is fitted. 8. The cross-sectional shape of the low-pressure side sealing material is formed so as to cover the outer peripheral portion of the high-pressure side sealing material, and each of these sealing materials is accommodated in a common annular groove formed on the joint surface. The seal structure according to claim 5. 9. The seal structure according to claim 5, wherein the low-pressure side sealing material is disposed eccentrically with respect to the high-pressure side sealing material. 10. The seal structure according to claim 5, wherein a radial thickness of the low-pressure side sealing material is partially reduced. 11. The seal structure according to claim 5, wherein a concave portion is formed on an inner peripheral surface of the low-pressure side seal material so as to face an outer peripheral surface of the high-pressure side seal material.