JP3695092B2 - Fuel hose - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel hose. In particular, the invention is suitable for preventing static electricity by discharging (discharging) static electricity generated by fuel flow.
[0002]
[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.
[0003]
For example, inside the main body layer 18 made of polyamide such as nylon 11 and nylon 12, which has excellent gasohol resistance, moisture permeation resistance and flexibility, gasoline resistance compared to the nylon 11 and nylon 12, An inner layer (innermost tube layer) made of a fluororesin material that is far superior in various physical properties such as gasoline permeation resistance is formed (see US Pat. No. 5,383,087, etc.).
[0004]
And the resin-made fuel hose tends to generate static electricity due to fuel flow or the like. It is necessary to prevent the occurrence of static electricity failure by suppressing the amount of charge of the generated static electricity below a certain level.
[0005]
For this reason, normally, the innermost tube layer 20 is formed of a material that is likely to generate static electricity and has a predetermined or less (usually 1 × 10 ⁸ or less) leakage resistance in the innermost tube layer 20, and the innermost tube Layer 20 was the antistatic layer. That is, the static electricity generated in the innermost pipe layer 20 is made of metal that is connected to the nipple 17 of the connector 16, which is a conductive material such as steel, and further to the connector (joint) 16 and is grounded. The charge was removed via the pipe 14 (see FIG. 2).
[0006]
For example, in the case of the fuel hose having the multilayer structure described in the above-mentioned US patent specification, the conductive inorganic filler is mixed with the fluororesin material forming the inner layer (innermost tube layer) 20.
[0007]
It is necessary to add the conductive inorganic filler in consideration of the effects of low tempe-rature durability and resistance to the degradative effects of gasoline or fuel. There is a description (the sixth column, the 44th row to the seventh column, the second row).
[0008]
[Problems to be solved by the invention]
However, in the case of the fuel hose configured as described above, the following problems are likely to occur.
[0009]
When a member A having a high charged voltage approaches the fuel hose, a spark is generated toward the innermost tube layer 20 as indicated by a two-dot chain line. This is because the innermost tube layer 20 is a layer that has a lower resistance than other portions and easily conducts electricity (see FIG. 1).
[0010]
Further, when the innermost tube layer is formed of a fluororesin material or the like, the blending of the conductive inorganic filler tends to lower the characteristics of the fluororesin as described above.
[0011]
In view of the above, an object of the present invention is to provide a fuel hose that does not promote deterioration of each layer of the fuel hose even if a spark is generated due to close proximity of a member having a high charged voltage.
[0012]
Another object of the present invention is to provide a fuel hose that has no fear of deteriorating the characteristics of the fluororesin material when the innermost tube layer is formed of a fluororesin material or the like.
[0013]
[Means for Solving the Problems]
The fuel hose according to the present invention solves the above problems by the following configuration.
[0014]
In the fuel hose in which the hose body is formed of an insulating resin and has a joint connected to a ground conductor at at least one end of the hose body,
The fuel hose is provided with a static elimination intervening layer on the outer surface side of the hose body entirely or partially,
The static elimination intervening layer has an electrical resistance characteristic satisfying either a volume resistivity of 1 × 10 ¹⁰ Ω · cm or less and a surface resistivity of 1 × 10 ¹⁰ Ω or less.
A static elimination path to the ground conductor for static electricity generated on the inner surface of the hose body is formed.
[0015]
Here, the antistatic layer is preferably formed of a rubber compound vulcanizate having a carbon fraction of 20 to 40% or a conductive coating layer.
[0016]
In each of the above inventions, the hose body is a multilayer structure including a main body layer and an innermost pipe layer formed inside the main body layer, and the innermost pipe layer is formed of an insulating fluororesin material. It is suitable when it is made of an insulating resin material that can be applied to the hose.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of the present invention will be described mainly based on FIG.
[0018]
(1) A fuel hose 10 according to the present invention includes a hose body 12 formed of an insulating resin and a joint 16 connected to a ground conductor (metal fuel pipe) 14 at at least one end of the hose body 12. Is a superordinate conceptual configuration.
[0019]
In the illustrated example, the hose body 12 has a two-layer structure including a main body layer 18 and an inner layer 20 that is the innermost tube layer. However, the hose body 12 may have a single-layer structure or a multilayer structure of 3 to 6 layers. Of course, there is no problem. Here, the insulating resin for forming the main body layer 18 is not particularly limited as long as it satisfies the characteristics required for the fuel hose, but has superior gasohol resistance and water absorption compared to nylon 6 and nylon 66. Nylon 11 and nylon 12 which are small and have flexibility and low temperature resistance are desirable.
[0020]
Here, the thickness of the main body layer 18 is usually 0.5 to 2.5 mm, preferably 0.7 to 1.5 mm in the case of a single layer, and usually 0.3 to 1 in the case of a multilayer. 0.5 mm, preferably 0.5 to 1.0 mm, so that the overall thickness is the same as that of a single layer.
[0021]
If the wall thickness is too thin, it is difficult to ensure the gas hose resistance, gasoline resistance, gasoline permeability resistance, moisture permeability resistance, etc. required for the fuel hose. When the static elimination intervening layer 22 described later is formed, if the wall thickness is too thick, when the static elimination intervening layer 22 described later is formed, discharge of static electricity generated on the inner surface of the hose body 12 to the static elimination intervening layer (charge transfer) This makes it difficult to obtain a static elimination effect, impairs the flexibility of the fuel hose, and results in excessive quality.
[0022]
Further, as described above, the innermost tube layer 20 formed inside the hose body layer 18 is preferably formed of an insulating fluororesin material. Examples of fluororesin include polyvinylidene fluoride, tetrafluoroethylene-ethylene copolymer (ETFE resin), tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride terpolymer ( THV resin), tetrafluoroethylene-perfluorovinyl ether copolymer and mixtures thereof can be suitably used. The wall thickness of the inner layer 20 is usually 0.05 to 0.5 mm, preferably 0.1 to 0.3 mm. If the wall thickness is too thin, extrusion molding becomes difficult, and it is difficult to expect improvement in required fuel hose characteristics by forming the inner layer with a fluororesin. If the wall thickness is too thick, the flexibility of the fuel hose is hindered and the quality is excessive as in the case of the main body layer.
[0023]
If the insulating resin material constituting the innermost tube layer 20 is not included in the insulating resin material forming the main body layer 18 or is provided with one or both of the hose required characteristics superior thereto, the fluorine resin is used. It is not limited to resin.
[0024]
When the main body layer 18 is made of nylon and the inner layer 20 is made of a fluororesin, both cannot be melt-bonded, and therefore an adhesive layer is usually interposed.
[0025]
As a material for forming the adhesive layer, one having the following constitution described in the aforementioned US patent specification can be preferably used, and the thickness thereof is set to 0.05 to 0.15 mm.
[0026]
“Vinylidene fluoride / chlorotrifluoroethylene copolymer: about 35-45 wt%, polyvinylidene fluoride: about 25-35 wt%, one of nylon 11 and nylon 12, or a mixture thereof: essentially about 25-35 wt% What will be. "
Each of these layers may be formed sequentially from the inside by using a crosshead independently, but of course, co-extrusion may also be used.
[0027]
(2) The fuel hose 10 of the present invention is provided with a static elimination intervening layer 22 on the outer surface side of the hose body 12 entirely or partially. The static elimination intervening layer 22 has an electrical resistance characteristic that satisfies a volume resistivity of 1 × 10 ¹⁰ Ω · cm or less and a surface resistivity of 1 × 10 ¹⁰ Ω or less. Examples of the static elimination intervening layer 22 include a conductive resin, a conductive thermoplastic elastomer, and a metal.
[0028]
With this configuration, it is possible to form a static elimination path (solid line arrow in FIG. 2) of static electricity generated on the inner surface of the hose body 12 to the ground conductor.
[0029]
Here, when the electrical resistance characteristic of the static elimination intervening layer 22 does not satisfy the predetermined value or less as described above, the electrical resistance becomes too high and it becomes difficult to move the static electricity generated inside the hose to the static elimination intervening layer 22. Therefore, it becomes difficult to transfer the charge to the fuel pipe 14 which is the ground conductor. Here, the fuel pipe 14 is usually made of a metal and a conductor, but even if it is made of a resin, there is no problem as long as the electric resistance characteristic is made into a conductor so as to satisfy the above numerical values.
[0030]
At this time, in the case of being formed of the same insulating resin as that of the hose body 12, it is necessary to form a joint having a shape that allows a charge transfer between the fuel pipe 14 and the charge removal intervening layer 22. When the joint 16 is a conductor such as a metal, the joint shape need not be considered.
[0031]
When the thickness of the hose body 12 exceeds 3 mm, it becomes difficult to move the static electricity generated inside the hose to the static elimination intervening layer 22 as described above.
[0032]
Here, the antistatic layer 20 is preferably formed of a vulcanized product of a rubber compound having a carbon black fraction of 20 to 40%. When the carbon black fraction is less than 20%, it is difficult to reduce the volume resistivity to 10 ¹⁰ Ω · cm or less. When the carbon black fraction exceeds 40%, the rigidity of the vulcanized rubber tends to be high and the flexibility is improved. May interfere.
[0033]
The base polymer of the rubber compound is not particularly limited, but ethylene propylene rubber is desirable from the viewpoint of weather resistance, lightness, and the like. Moreover, as carbon black, furnace black and acetylene black which are easy to give electroconductivity are desirable.
[0034]
Moreover, the thickness of the static elimination intervening layer 22 is usually 0.5 to 3 mm, preferably 1 to 2 mm, when the structure also serves as a protector. And a formation site | part is good also as a cylindrical protector layer formed in the whole surface of the hose main body, but you may form in a spiral shape. Furthermore, it may be formed in a band shape along the longitudinal direction on the peripheral surface.
[0035]
Alternatively, a hard plastic material and a conductive inorganic filler may be blended, and a spiral spring-shaped material may be formed and wound around the hose body.
[0036]
As the conductive inorganic filler, carbon black, graphite, stainless steel, and other highly conductive metal materials such as copper, silver, and gold can be used.
The above can be used. In this case, a slight air discharge (see the dotted arrow in FIG. 2) can be expected if the surface is formed by spraying acute-angled protrusions.
[0037]
(3) Another aspect of the static elimination intervening layer is formed of the conductive coating film 22A. At this time, a conductive coating film having a surface resistivity of 10 ¹⁰ Ω or less is usually formed.
[0038]
As a means for forming the conductive coating film 22A, conductive coating application, conductive ink printing, electroplating, vacuum deposition, metal spraying, sputtering, ion plating, etc. are optional, but from the viewpoint of productivity, etc. Application or conductive ink printing is desirable.
[0039]
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, since high conductivity is not required here, low-cost carbon black or graphite is desirable.
[0040]
Further, as the synthetic resin serving as the binder, those having good adhesion to the main body layer 18 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.
[0041]
Here, the formation portion of the antistatic layer may be the entire surface, but may be formed in a band shape, a spiral shape, or a dotted line shape with a minute gap (usually 1 to 2 mm or less) along the longitudinal direction. Further, a mark for identification may be formed on the hose surface with conductive ink.
[0042]
[Operation and effect of the invention]
The fuel hose of the present invention is a fuel hose in which a hose body is formed of an insulating resin and has a joint connected to a ground conductor at at least one end of the hose body. The neutralization intervening layer has a structure in which the electric resistance characteristic is not more than a predetermined value and a static elimination path to the ground conductor for static electricity generated on the inner surface of the hose body is formed. The following operations and effects are achieved.
[0043]
When a member having a high charged voltage comes close to the fuel hose, a spark is generated, but the spark is generated between the neutralization intervening layer formed on the surface side of the hose body. Therefore, the spark does not penetrate the hose body and does not promote deterioration of the hose body based on the spark.
[0044]
In addition, when the hose body has a multi-layer structure and the innermost tube layer is formed of an insulating resin material such as a fluororesin, a conductive material is added to the insulating resin material to prevent charging as in the past. There is no need to blend. Therefore, when the innermost tube layer is formed of a fluororesin material or the like, there is no possibility of deteriorating the characteristics of the fluororesin or the like.
[0045]
[Test example]
Hereinafter, test examples conducted for confirming the effects of the present invention will be described.
[0046]
The sample hose body has an outer diameter of 8 mm, an innermost tube layer: fluororesin (ETFE resin) 0.2 mmt, an adhesive layer: fluororesin / nylon alloy 0.1 mmt, and a body layer: nylon 11 0.7 mmt. Each sample hose was prepared by cutting the one formed by co-extrusion into 500 mm, and connecting the joints (made of nylon 12) shown in FIG. 2 to both ends.
[0047]
In addition, the volume resistivity of the forming material of each layer is ETFE resin: 3.0 × 10 ¹⁸ Ω · cm, nylon 12: 4 × 10 ¹⁴ Ω · cm.
[0048]
A hose-shaped protector having a wall thickness of 1.8 mm was extruded from an EPDM blend (sulfur vulcanization system, carbon black (FEF) fraction: 27%) and cut into a length of 500 mm. The volume resistivity of this protector (EPDM vulcanized rubber) is 1.4 × 10 ⁷ Ω · cm.
[0049]
The hose with a joint is piped with a metal pipe so that a gasoline alternative liquid (volume resistivity: 10 ¹³ to 10 ¹⁴ Ω · cm) can be circulated, and a grounded aluminum plate is arranged below the lower surface 430 mm of the hose. A sensor of an electrostatic capacitance meter (manufactured by TREK) was disposed above the center of the joint sample hose.
[0050]
Then, the protector 22 is cut in the axial direction on the hose body 12 and placed from the top side so as to cover none, ¼ lap, ½ lap, and all laps. The neutralization intervening layer 22 was used, and a charged voltage measurement test was conducted. The distance between the sensor and the upper surface of the protector was 5 mm.
[0051]
Thus, the result of the measurement test is shown in FIG.
[0052]
The test results show that even if the contact area is ¼, there is a static elimination effect that is not much different from the case of the entire circumference.
[Brief description of the drawings]
1 is a cross-sectional view showing an example of a conventional fuel hose. FIG. 2 is a partial vertical cross-sectional view showing an embodiment of a fuel hose of the present invention. FIG. 3 is a cross-sectional view showing another embodiment. FIG. 5 is a model diagram showing each aspect of placement of the protector (static elimination intervening layer) on the hose body in the test of the present invention. FIG. 5 is a graph showing the measurement result of the charged voltage of the present invention.
10 Fuel hose 12 Hose body 14 Ground conductor (fuel piping)
16 Joint 18 Body layer 20 Inner layer (innermost tube layer)
22 Static electricity removal intervening layer (protector)
22A Static elimination intervening layer (conductive coating layer)

Claims (4)

The hose body has a thickness of 0.5 to 2.5 mm, is formed of an insulating resin, and has a joint connected to a ground conductor at at least one end of the hose body, and further, an outer surface of the hose body In the fuel hose with the static elimination intervening layer on the side ,
The charge-eliminating intervening layer, the electrical resistance properties, volume resistivity 1 × ¹⁰ 10 Ω · cm or less, satisfies either surface low efficiency 1x10 ¹⁰ Omega less, and rubber is carbon fraction 20-40% It is a separate protector from the hose body formed of a vulcanized product .
A fuel hose characterized by forming a static elimination path for static electricity generated on the inner surface of the hose body to the ground conductor. The fuel hose according to claim 1 , wherein the protector is cylindrical . The fuel hose according to claim 2, wherein the thickness of the protector is 0.5 to 3 mm . The hose body has a multilayer structure including a main body layer and an innermost pipe layer formed inside the main body layer, and the innermost pipe layer is formed of an insulating fluororesin material. The fuel hose according to any one of claims 1 to 3 .

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