Electricity: electrical systems and devices – Discharging or preventing accumulation of electric charge
Reexamination Certificate
1999-04-07
2002-08-27
Fleming, Fritz (Department: 2836)
Electricity: electrical systems and devices
Discharging or preventing accumulation of electric charge
C361S215000
Reexamination Certificate
active
06442012
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is based on Japanese Patent Application No. Hei. 10-94899, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a coupling mechanism structured to connect a resin fuel hose with a metal pipe, and more particularly to a coupling mechanism including a resin coupling body having a pipe inserting section configured to permit the metal pipe to be inserted thereinto which is designed so that an O-ring can be fitted in an inner wall of the pipe inserting section of the coupling body.
In this specification, the term “electrical deterioration of resin” means that current flows in the contact part of different types of members, so that the resin is deteriorated. An electrical deterioration of the resin may include electrolytic deterioration and thermal (Joule heat) deterioration.
2. Description of Related Art
Japanese Patent Publication No. Hei. 4224394 presents general technical material to this topic level and is herein incorporated by reference.
A resin fuel hose generally requires a compound having characteristics such as resistance to gasoline and gasohol, and gasoline and moisture permeability resistance. Therefore, generally, a hose body
12
is of a multi-layer structure as shown in FIG.
1
.
For instance, the resin fuel hose is designed as follows: A body layer
14
is formed of polyamide such as nylon, or the like, having excellent gasohol and moisture permeability resistance, and excellent flexibility. An inner layer (the innermost layer)
16
of fluoro-resin material has much higher gasoline resistance and gasoline permeability resistance than the nylon inside the body layer
14
. See, for example, U.S. Pat. No. 5,383,087.
The inner surface of the resin fuel hose may become electrostatically charged by the flow of fuel. Therefore, it is necessary that the amount of electrostatic charge is suppressed to a predetermined value in order to prevent the occurrence of electrostatic trouble.
In order to discharge the static electricity (charge), the quick connector is generally made of a resin which has a volume resistivity lower than 10
6
&OHgr;·cm or a surface resistivity lower than 10
6
&OHgr;. If the elctrically conductive quick connector is made of resin, for example, it can be more easily manufactured ( injection molding can be utilized) and will have a reduced weight.
It has been found, however, that the resin quick connector having the above-described electrical resistance also electrically deteriorates more rapidly.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the invention is to provide a fuel hose resin coupling in which the coupling body has a slow electric deterioration.
The inventors have conducted intensive research on the solution of the above-described problem, and found that the cause for the electrical deterioration of the resin coupling is as follows:
In the discharge path (or charge leak path) of the inner layer
16
, the coupling body
24
, and the metal pipe
22
, a gap which is for the assembling of the metal pipe
22
and the coupling mechanism
18
is provided between the metal pipe
22
and the pipe inserting section
26
of the coupling body
24
. The gap between the metal pipe
22
and the pipe inserting section
26
is sealed with O-rings
28
. Because of the function of the O-ring
28
, its electrical resistance is high enough to prevent the leakage of static electricity. In order to lower the electrical resistance, a large quantity of carbon black is employed to reduce the electrical resistance of the O-ring. However, in order to seal the gap well, it is not suitable to employ a large quantity of carbon black.
Therefore, moving the charge from the inner layer
16
to the coupling body
24
occurs as follows: when the metal pipe
22
is brought into point-contact with the coupling body
24
because of the vibration of the traveling vehicle, current in the form of static electricity flows in the inner layer
16
, in the contact part of the coupling body
24
and the metal pipe
22
. This current is a factor which expedites the deterioration (or dissolution) of the resin coupling body
24
of resin.
That is, the static electricity generated in the inner layer
16
is removed through a nipple
20
of coupling mechanism
18
and through the metal pipe
22
which is connected to the coupling mechanism
18
and grounded, as shown in
FIG. 2
The quick connector
18
is constructed such that O-rings are fitted in the inner cylindrical wall of the pipe inserting section
26
of the coupling body
24
. This is to connect the metal pipe to coupling
18
in one action.
In this connection, it has been found that, if the electrical resistance of the coupling body
24
is in a predetermined range, then the current which expedites the deterioration of the coupling body
24
does not flow in the contact part of the coupling body
24
and the metal pipe
22
. As a result, the following fuel hose resin coupling has been created.
The coupling mechanism
18
according to the present invention has an O-ring
28
fitted in the inner cylindrical wall of the pipe inserting section
26
of the coupling body
24
. A specific feature of the coupling mechanism
18
is that the volume resistivity of the coupling body
24
is within a range of 10
6
to 10
10
&OHgr;·cm and the surface resistivity is within a range of 10
6
to 10
10
&OHgr;.
In this connection, it is preferable that the coupling body
24
has an electrically conductive film
30
, because the surface resistivity of the coupling body
24
can be readily set in the above-described range.
In addition, it is preferable that an electrically conductive elastic member
32
is arranged on the bottomed step
27
of the pipe inserting section
26
. In this embodiement, it is preferable that each of the volume and surface resistivities of the elastic member
32
is smaller than those of the coupling body
24
, because the discharge path is well maintained.
Features and advantages of the invention will be evident from the following detailed description of the preferred embodiments described in conjunction with the attached drawings.
REFERENCES:
patent: 3891290 (1975-06-01), Marshall
patent: 3943273 (1976-03-01), de Putter
patent: 3982157 (1976-09-01), Azuma
patent: 4394705 (1983-07-01), Blachman
patent: 4658326 (1987-04-01), Clark et al.
patent: 5143122 (1992-09-01), Adkins et al.
patent: 5164879 (1992-11-01), Danowski et al.
patent: 5382359 (1995-01-01), Brandt
patent: 5491013 (1996-02-01), Holley
patent: 5511840 (1996-04-01), Allison
patent: 5613524 (1997-03-01), Martucci
patent: 5855036 (1999-01-01), Krock
patent: 5931510 (1999-08-01), Mathew et al.
patent: 4310159 (1999-04-01), None
patent: 4-224394 (1992-08-01), None
The McGraw-Hill Dictionary of Scientific and Technical Terms, Fifth Edition p. 1962.*
Concise Explanation of JP 04-224394A.
SAE J 1645, Jan. 1999.
Bito Shinichi
Goto Hisatsugu
Kato Takayuki
Koike Masaki
Miyamoto Yasushi
Fleming Fritz
Toyoda Gosei Co,., Ltd.
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