JP3673916B2 - Resin fitting for fuel hose - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin joint connected to a resin fuel hose. More specifically, the present invention relates to a resin joint having an O-ring incorporated in an inner peripheral wall of a pipe insertion portion of a joint body.
[0002]
In this specification, “electrical degradation of resin” refers to degradation that occurs in the resin due to the flow of current between contact parts of different members, such as galvanic (electrolytic) degradation and thermal (joule heat) degradation. Is presumed to be mixed.
[0003]
In addition, there is JP-A-4-224394 as a document indicating a general technical level, not a document particularly related to the present invention.
[0004]
[Background]
Resin-made fuel hoses are usually required to have gasoline resistance, gasohol resistance, and composite characteristics such as gasoline permeability resistance and moisture permeability resistance. For this reason, the hose body 12 usually has a multilayer structure as shown in FIG.
[0005]
For example, inside the main body layer 14 made of polyamide, such as nylon 11, nylon 12, etc., which has excellent gasohol resistance, moisture permeability resistance and flexibility, gasoline resistance compared to nylon 11, nylon 12; An inner layer (innermost tube layer) 16 made of a fluororesin material that is far superior in various physical properties such as gasoline permeation resistance is formed (US Pat. No. 5,383,087 (Japanese Patent Publication No. 7-507739) ) Etc.).
[0006]
The resin fuel hose is easily charged with static electricity on the inner surface due to fuel flow or the like. It is necessary to prevent the occurrence of static electricity failure by suppressing the amount of static electricity from becoming larger than a predetermined value.
[0007]
For this reason, normally, the inner layer 16 is formed of a material that is likely to generate static electricity, and the electric resistance of the inner layer 16 is a predetermined value or less (usually 1 × 10 ⁸ Ω or less). (Charge) was caused to leak to other conductive members.
[0008]
That is, static electricity generated in the inner layer 16 is transmitted through a nipple 20 of a quick joint (quick connector) 18 having conductivity, and further through a metal pipe 22 connected to the quick joint 18 and grounded (grounded). The charge was removed (see FIG. 2).
[0009]
Here, the quick joint 18 has a configuration in which an O-ring 28 is incorporated in the inner peripheral wall of the pipe insertion portion 26 of the joint body 24. This is because the metal pipe 22 is connected to the joint 18 with one touch.
[0010]
On the other hand, as for the quick joint having the conductivity, a resin-made quick joint is becoming mainstream from the viewpoint of assembling performance, productivity (injection molding possible), and weight reduction.
[0011]
The quick joint made of the resin used one whose electric resistance is usually 10 ⁶ Ω · cm or less in terms of volume resistivity or 10 ⁶ Ω or less in terms of surface resistivity in order to perform the static elimination route quickly. .
[0012]
[Problems to be solved by the invention]
However, it has been found that in the case of a resin quick joint (quick connector) having electrical resistance as described above, electrical deterioration tends to be promoted.
[0013]
In view of the above, an object of the present invention is to provide a resin joint for a fuel hose that hardly causes electrical deterioration in the joint body.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have found that the cause of electrical deterioration of the resin joint is as follows in the process of earnestly developing.
[0015]
In the static elimination path (charge leakage path) composed of the inner layer 16 → the joint body 24 → the metal pipe 22, the metal pipe 22 and the joint 18 are assembled between the metal pipe 22 and the pipe insertion portion 26 of the joint body 24. There exists a gap (gap) for ensuring the safety. The gap between the metal pipe 22 and the pipe insertion portion 26 is sealed with an O-ring 28. However, the O-ring 28 cannot have a low electrical resistance due to the function of static electricity. In order to reduce the electrical resistance, it is necessary to add a large amount of carbon black to impart conductivity, but it is difficult to add a large amount to ensure sealing properties.
[0016]
Therefore, when the metal pipe 22 is in point contact with the joint body 24 due to vibration or the like when the vehicle travels, the charge that has moved from the inner layer 16 to the joint body 24 is between the contact portions of the joint body 24 and the metal pipe 22. Current flows. This current becomes a factor that promotes deterioration (decomposition) of the resin-made joint body 24.
[0017]
In this case, by making the electrical resistance of the joint body within a predetermined range, it has been found that a current that promotes deterioration of the joint body 24 does not flow between contact portions of the joint body 24 and the metal pipe 22. The present inventors have conceived a resin joint for fuel hose having a configuration.
[0018]
A resin joint connected to a resin fuel hose and pipe,
In the resin-made joint having a configuration in which an O-ring is incorporated in the inner peripheral wall of the pipe insertion portion of the resin joint body, and there is a gap between the inner peripheral wall and the inserted pipe ,
An elastic member having conductivity is disposed between the joint main body and the pipe insertion portion, and a static elimination path is formed by the joint main body, the elastic member, and the pipe. At this time, it is desirable that the elastic member having conductivity is disposed on the bottomed step portion of the pipe insertion portion. Furthermore, it is desirable that the electrical resistance of the elastic member is lower by one digit or more in volume resistivity and surface resistivity than the electrical resistance of the joint, so that the static elimination path can be easily secured.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the resin joint of the present invention will be described mainly based on FIG.
[0020]
(1) The resin joint of the present invention is connected to a resin fuel hose (hose body) 12 and an O-ring 28 is incorporated in the inner peripheral wall of the pipe insertion portion 26 of the joint body 24, so-called rapid The structure of the joint (quick connector) is a superordinate conceptual structure.
[0021]
In the illustrated example, the hose body 12 has a two-layer structure including a main body layer 14 and an inner layer 16 serving as an innermost tube layer. However, the hose body 12 may have a single-layer structure or a multi-layer structure of 3 to 6 layers. Of course, there is no problem. In the figure, 25 is an elastomeric hose protector.
[0022]
Here, the insulating resin for forming the main body layer 14 is not particularly limited as long as it satisfies the characteristics required for the fuel hose, but has superior gasohol resistance and water absorption as compared with nylon 6 and nylon 66. Nylon 11 and nylon 12 which are small and have flexibility and low temperature resistance are desirable.
[0023]
The inner layer 16 formed inside the hose body layer 14 is preferably formed of a conductive fluororesin material.
[0024]
In the case where the main body layer 14 is made of nylon and the inner layer 16 is made of a fluororesin, both cannot be melt-bonded.
[0025]
As a method for imparting the electrical resistance within the above range to the quick joint 18, even if it is molded with a hard resin material in which a conductive filler is blended with a hard resin material, the surface of the joint body 24 molded with the hard resin material is shown in FIG. As shown in FIG. 2, the conductive coating film 30 may be formed.
[0026]
Here, as the hard resin material, polyacetal (POM), polyamide (PA), polyvinyl chloride (PVC), polyester, polypropylene or the like can be suitably used.
[0027]
As the conductive filler, carbon black, graphite, stainless steel, and other highly conductive metal materials such as copper, silver, and gold can be used.
[0028]
The conductive coating film 30 may be formed by any means such as conductive paint application, conductive ink printing, electroplating, vacuum deposition, metal spraying, sputtering, ion plating, etc., but from the standpoint of productivity, etc. Application or conductive ink printing is desirable.
[0029]
Here, the conductive paint / ink is composed of a conductive filler, a binder such as a synthetic resin, a solvent, and an additive, and refers to a paint that exhibits conductivity when cured. Here, as the conductive filler, those described above can be used. However, in the case of a conductive coating film, since high conductivity is not required, low-cost carbon black or graphite is desirable.
[0030]
Furthermore, as the synthetic resin serving as the binder, those having good adhesion to the main body layer 14 are preferable. For example, when the main body layer is formed of nylon 11, nylon 12, or the like, polyurethane, acrylic resin (including ultraviolet curable type), alkyd resin, and the like are excellent in weather resistance and the like.
[0031]
In the above configuration, as shown in FIG. 3, an elastic member 32 having conductivity is disposed on the bottoming step portion 27 of the pipe insertion portion 26, and the electric resistance of the elastic member 32 is determined by the electric resistance of the joint body 24. By setting the volume resistivity and surface resistivity to values that are lower by one digit or more (preferably 2 to 3 digits), it is possible to form a direct and stable static elimination path by electric conduction (including charge transfer). For this reason, electrical conduction is smoothly performed from the joint body 24 to the metal pipe 22, and electric charge does not accumulate in the joint body 24, and a large current flows between the contact parts of the joint body 24 and the metal pipe 22. It can be prevented more reliably.
[0032]
Here, the elastic member 32 is not limited to conductive rubber as shown in the figure, and may be a coil spring, a leaf spring, or the like formed of metal or conductive hard plastic.
[0033]
[Operation and effect of the invention]
By disposing an elastic member having conductivity at the bottom of the pipe insertion portion, a direct and stable static elimination path by charge transfer can be formed.
[0034]
For this reason, electric conduction is smoothly performed from the joint body to the metal pipe, and no electric charge is charged in the joint body, so that a large current flows reliably between the contact portions of the joint body 24 and the metal pipe 22. It can be prevented more reliably. Therefore, the electrical deterioration of the resin joint body can be more effectively prevented.
[0035]
Here, when the joint body is provided with a conductive coating on the surface, it is possible to easily prepare the joint body having the surface resistivity.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a fuel hose. FIG. 2 is a cross-sectional view showing an embodiment of a resin joint of the present invention. FIG. 3 is a cross-sectional view showing another mounting mode of the present invention. Sectional view of a resin joint formed with a conductive coating film of the invention [Explanation of symbols]
12 Hose body 18 Quick fitting (Quick connector)
20 Nipple 22 Metal pipe 24 Joint body 26 Pipe insertion part 27 Bottoming step part 28 O-ring 30 Conductive coating film 32 Conductive elastic member

Claims (4)

A resin joint connected to a resin fuel hose and pipe,
In the resin-made joint having a configuration in which an O-ring is incorporated in the inner peripheral wall of the pipe insertion portion of the resin joint body, and there is a gap between the inner peripheral wall and the inserted pipe ,
An elastic member having conductivity is disposed on the bottomed step portion of the pipe insertion portion of the joint body, and a static elimination path is formed by the joint body, the elastic member, and the pipe,
The resin joint for a fuel hose, wherein the electrical resistance of the elastic member is lower by one digit or more in volume resistivity and surface resistivity than the electrical resistance of the joint body.   The resin joint for a fuel hose according to claim 1, wherein the electrical resistance of the elastic member is set to a value that is two digits or more lower in volume resistivity and surface resistivity than the electrical resistance of the joint body. A connection structure between a resin joint having conductivity and a metal pipe connected to a resin fuel hose,
In the resin-made joint having a configuration in which an O-ring is incorporated in the inner peripheral wall of the pipe insertion portion of the resin joint body , and there is a gap between the inner peripheral wall and the inserted pipe ,
An elastic member having conductivity is arranged in the bottomed step portion of the pipe insertion portion of the joint body to form a static elimination path, and the electrical resistance of the elastic member is determined by the volume resistivity and the surface from the electrical resistance of the joint body. A connection structure for a resin joint for a fuel hose, wherein each of the resistivity values is lower by one digit or more.   4. The resin joint for a fuel hose according to claim 3, wherein the electrical resistance of the elastic member is lower by two digits or more in volume resistivity and surface resistivity than the electrical resistance of the joint body. 5. Connection structure.

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