JP6363923B2 - Volatile fuel gasket - Google Patents

Description

  The present invention relates to a volatile fuel gasket, and more particularly to a volatile fuel gasket that is compressed and sandwiched between members to seal between the members.

  Conventionally, in order to prevent permeation of volatile fuel used in a fuel system, a gasket for volatile fuel that seals a container or a tube has been used. For example, it is used in a joint portion of a volatile fuel pipe in an automobile fuel system, and the volatile fuel gasket of this system is required to have high low permeability to volatile fuel. Also, in cold districts, the gasket loses its elasticity due to a decrease in temperature, so that it loses its adhesion to members such as pipe joints, creating a gap between the member and the gasket, and allowing volatile fuel to permeate. In order to prevent this, it is necessary to have a high elasticity maintaining property against a temperature drop.

  In view of the above, Patent Document 1 proposes a rubber seal structure having low permeability to volatile fuel and elasticity maintenance against temperature decrease, and is compressed and sandwiched between members as in the present invention. A technology relating to a volatile fuel gasket for sealing between members is disclosed. Hereinafter, a description will be given with reference to FIG.

  The seal structure 60 installed at the joint portion of the tubular body has a structure in which a member on the inner peripheral side 62 and a member on the outer peripheral side 64 are arranged concentrically with respect to the fluid flow center. Is made of ternary fluororubber consisting of tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and hexafluoropropylene (HFP) having high fluid tightness at normal temperature. It consists of a ternary fluororubber composed of dense tetrafluoroethylene (TFE), vinylidene fluoride (VDF), and perfluoromethyl vinyl ether (PFMVE).

JP 2004-190806 A

  However, in the seal structure of Patent Document 1, the cross-sectional structure is a vertically divided structure of the inner peripheral member and the outer peripheral member, and they are made of different materials. Therefore, there has been a problem that it is necessary to eliminate the deterioration of the adhesion state of both members due to the stress at the time of deformation from the situation where the deformation amount of both members is different at the time of high compression or swelling.

  Furthermore, at low temperatures, the vertically divided outer peripheral member can maintain fluid tightness (including elasticity), but the inner peripheral member loses its elasticity. Therefore, the member on the inner peripheral side has poor adhesion to the member to be sealed, leading to the generation of a gap. As a result, the sealing performance must be guaranteed only by the outer peripheral member, and the reliability may be impaired.

  The present invention has been made in view of the conventional problems as described above, and the object thereof is to have high elasticity maintenance even in a low temperature range while having high low permeability to volatile fuel. Another object of the present invention is to provide a volatile fuel gasket capable of maintaining good sealing performance between members to be sealed.

In order to achieve the above object, the invention according to claim 1 is a volatile fuel gasket that is compressed and sandwiched between members to seal between the members, and a core material and a surface layer that covers the surface of the core material. The core material and the surface layer are both made of fluoro rubber, the core material is circular in cross section, and the fluoro rubber constituting the core material is made of ternary fluoro rubber And has a lower permeability to volatile fuel than the fluororubber constituting the surface layer, and the surface layer surrounds the entire periphery of the core material with a substantially uniform thickness. The fluorine rubber to be formed is made of a binary fluorine rubber, and has a higher elasticity maintaining property against a temperature drop than the fluorine rubber to form the core material.

The invention according to claim 2 is the gasket for volatile fuel according to claim 1, wherein the core material is made of ternary fluororubber having vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene, The surface layer is made of a binary fluororubber having vinylidene fluoride and tetrafluoroethylene.

  According to this configuration, the entire outer periphery of the surface of the core material is covered with the surface layer. That is, since the surface layer has a cross-sectional structure surrounding the core material instead of a vertically divided cross-sectional structure, stress generated during high compression or swelling is not easily biased and peeling between both members is difficult to occur.

  Further, since the surface layer covers the entire surface of the core material, the surface layer in a compressed state sandwiched between the members to be sealed is firmly in contact with the opposing surface of the member to be sealed at its outer peripheral surface. The state is secured. Here, the fluororubber constituting the surface layer has a higher elasticity maintaining property against temperature drop than the fluororubber constituting the core material, and can maintain adhesion more than the core material even at low temperatures. And the sealing property between the members is ensured. As a result, it is possible to achieve both the good low permeability to the volatile fuel in the normal temperature range and the good elasticity maintaining property in the low temperature range with a good balance.

In addition, a binary fluororubber having excellent elasticity maintenance in a low temperature region is used as the fluororubber of the surface layer, and an excellent low resistance to volatile fuel among the fluororubber as the fluororubber of the core material. By using the ternary fluororubber having permeability, it is possible to achieve a good balance between the properties of both good low permeability to volatile fuel in the normal temperature range and good elasticity maintenance in the low temperature range. .

  The invention according to claim 3 is characterized in that the thickness of the surface layer is set to a thickness capable of ensuring a substantially minimum compression rate.

  According to this structure, since the thickness of the surface layer is formed to a thickness that can ensure a minimum compression rate, a larger volume of the core material can be secured. Therefore, as a premise, it is possible to maintain an adequate elasticity maintaining property even in a low temperature range while sufficiently ensuring low permeability to a volatile fuel in a normal temperature range. That is, in a volatile fuel gasket, it is basically important to ensure low permeability first, so the thickness of the surface layer should be minimized while ensuring low overall permeability. It is specified to the required thickness.

  According to the present invention, since the surface layer surrounds the core material and the entire periphery of the core material, stress generated during high compression or swelling is not easily biased, and separation between both members is difficult to occur.

  Further, in a state where the surface layer is compressed by being sandwiched between the sealing target members, the outer peripheral surface of the surface layer is pressed against both of the opposing sealing target members. As a result, the sealed state can be maintained with good elasticity maintenance not only in the normal temperature range but also in the low temperature range, and the reliability of the sealing function in all climates is improved.

It is explanatory drawing of the whole shape of the gasket for volatile fuel which concerns on embodiment of this invention. Similarly, it is sectional drawing which shows the use condition of the gasket for volatile fuels. Similarly, it is explanatory drawing of the state by which the gasket for volatile fuels is compression-clamped. Similarly, it is explanatory drawing of the cross-sectional structure of the gasket for volatile fuels. Similarly, it is explanatory drawing of the cross-sectional shape of the state in which the gasket for volatile fuel is compression clamped. It is explanatory drawing of the seal structure which concerns on patent document 1. FIG.

  Next, an embodiment of a volatile fuel gasket according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 is an explanatory diagram of the overall shape of a volatile fuel gasket 10 according to an embodiment of the present invention. As shown in the figure, the volatile fuel gasket 10 has a substantially circular cross section and is a flat surface. The overall shape of the view forms a circular ring.

  FIG. 2 is a cross-sectional view showing a state where the volatile fuel gasket 10 according to the embodiment of the present invention is used in a fuel tank 20 for storing gasoline mounted on a vehicle. It is explanatory drawing of the state currently compression-clamped in the peripheral part 30 of the upper opening part 34 of the fuel tank 20 which is the object of sealing, and the flange part 32 of the pump 24. FIG.

  As shown in FIGS. 2 and 3, the volatile fuel gasket 10 is sandwiched between the upper surface of the peripheral portion 30 of the upper opening 34 of the fuel tank 20 and the lower surface of the flange portion 32 of the upper portion of the pump 24. The lock nut 22 is interposed in a compressed state by being screwed to the outer peripheral portion of the upper opening 34.

  That is, the volatile fuel gasket 10 seals between the peripheral edge portion 30 and the upper flange portion 32, seals the volatile fuel filled in the fuel tank 20, and opens the upper opening portion of the fuel tank 20. 34 from being released.

  FIG. 4 is an explanatory view of a cross-sectional structure of the volatile fuel gasket 10 according to the embodiment of the present invention.

  As shown in the figure, the volatile fuel gasket 10 has a cross-sectional structure including a core material 12 and a surface layer 14 covering the surface of the core material 12. In the present embodiment, the surface layer 14 having a substantially uniform thickness as a whole is formed in close contact with the outer peripheral surface of the core member 12 having a circular cross section. Therefore, it has a structure of two layers concentrically. Such a configuration can be easily manufactured, for example, by coating the outer surface of the core member 12 having a circular cross section with the material forming the surface layer 14.

  As described above, since the surface layer 14 surrounds the entire periphery of the core 12 having a circular cross section with a substantially uniform thickness, the volatile fuel gasket 10 is generated at the time of high compression or swelling. The stress is avoided from being concentrated unevenly, the core material 12 and the surface layer 14 are prevented from being peeled off, and the adhesion between the two members is always good.

  The core material 12 and the surface layer 14 are both formed of fluoro rubber, and the fluoro rubber constituting the core material 12 has higher low permeability to volatile fuel than the fluoro rubber constituting the surface layer 14; The fluororubber constituting the surface layer 14 has higher elasticity maintaining property against temperature decrease than the fluororubber constituting the core material 12.

  In the present embodiment, binary fluororubber is used as the fluororubber of the surface layer 14, and ternary fluororubber is used as the fluororubber of the core material 12.

  For example, as the binary fluorine rubber, it is possible to use a fluorine rubber having vinylidene fluoride (VDF), tetrafluoroethylene (TFE), etc., and as the binary fluorine rubber, vinylidene fluoride (VDF), Fluororubber having tetrafluoroethylene (TFE) or hexafluoropropylene (HFP) can be used. Therefore, for example, when used in an extremely cold region such as North America, the core material 12 formed of ternary fluororubber is almost lost in elasticity and is in a cured state. However, on the other hand, the surface layer 14 formed of binary fluorine rubber can maintain elasticity even in such an extremely cold region, and the peripheral portion 30 of the upper opening 34 of the fuel tank 20 and the pump described above. The outer peripheral surface closely adheres to the upper flange portion 32 of 24 with elasticity. Thereby, even in an extremely cold region, the volatile fuel filled in the fuel tank 20 can be reliably sealed.

  Next, the minimum compression rate will be described with reference to FIG. FIG. 5 is an explanatory diagram of a cross-sectional shape in a state where the volatile fuel gasket 10 is compressed and sandwiched. In the state of use, the volatile fuel gasket 10 is sandwiched and compressed between members to be sealed. It has become.

  First, the “compression ratio” of the volatile fuel gasket 10 is the cross-sectional thickness of the volatile fuel gasket 10 in a compressed state relative to the cross-sectional thickness of the volatile fuel gasket 10 in a non-compressed state. This is the ratio. The “minimum compression ratio” means that the minimum pressure required for the volatile fuel gasket 10 to be compressed and sandwiched between the members to seal the volatile fuel is volatile fuel. This is the compression ratio of the volatile fuel gasket 10 when it is applied to the gasket 10 for fuel.

  Since the surface layer 14 has a thickness sufficient to ensure the minimum compression rate, even if the core material 12 loses elasticity and is cured in a low temperature region, the compression amount is reduced to the surface layer 14. Is maintained, the outer peripheral surface of the surface layer 14 is kept in close contact with the member to be sealed (30, 32), and the sealing property between the members can be ensured. Further, the surface layer 14 is formed as thin as possible with a thickness necessary to ensure the minimum compression rate. That is, originally, the gasket 10 for volatile fuel in the normal temperature range is required to have low permeability to the volatile fuel as an important function. Therefore, it is basically required that the core material 12 of ternary fluororubber excellent in low permeability has a volume as large as possible. Therefore, the thickness of the surface layer 14 is formed so as to be suppressed to a thickness that can almost ensure the minimum compression rate, and a larger volume of the core material 12 is secured.

  Further, since the thickness of the surface layer 14 is formed almost uniformly over the entire circumference, the adhesion to the sealed target members (30, 32) in the compressed state is made uniform, and further, the internal stress is also biased. This prevents the separation between the core material 12 and the core material 12 effectively.

  In addition, this invention is not limited to the said embodiment, A various change is possible within the range which does not deviate from the summary of this invention. For example, in the above embodiment, the volatile fuel gasket 10 having a concentric cross-sectional structure is illustrated, but the cross-sectional shape of the volatile fuel gasket 10 may be a rectangle or a square. Moreover, the core material 12 is not limited to what is comprised as a single material or a single layer, You may set more than one.

DESCRIPTION OF SYMBOLS 10 Volatile fuel gasket 12 Core material 14 Surface layer 20 Fuel tank 22 Lock nut 24 Pump 30 Peripheral part 32 Flange part 34 Upper opening part

Claims (3)

In a volatile fuel gasket that is compressed between members and hermetically seals between the members,
Having a cross-sectional structure including a core material and a surface layer covering the surface of the core material;
The core material and the surface layer are both made of fluororubber,
The core material has a circular cross section, and the fluoro rubber composing the core material is made of ternary fluoro rubber, and has higher low permeability to volatile fuel than the fluoro rubber composing the surface layer. Have
The surface layer surrounds the entire periphery of the core material with a substantially uniform thickness, and the fluororubber constituting the surface layer is made of binary fluororubber, and has a temperature lower than that of the fluororubber constituting the core material. A gasket for volatile fuels, characterized by having a high elasticity maintaining property. The core material is composed of a ternary fluororubber having vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene,
2. The volatile fuel gasket according to claim 1, wherein the surface layer is made of a binary fluororubber having vinylidene fluoride and tetrafluoroethylene .   The volatile fuel gasket according to claim 1, wherein the thickness of the surface layer is a thickness that can ensure a minimum compression ratio.

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