Fluid handling – Diverse fluid containing pressure systems – Fluid separating traps or vents
Reexamination Certificate
2001-03-15
2002-06-25
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Fluid separating traps or vents
C137S043000, C137S587000
Reexamination Certificate
active
06408867
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of and priority from Japanese Applications No. 2000-92903 filed Mar. 30, 2000 and No. 2000-396453 filed Dec. 27, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel cutoff valve to be mounted on an upper wall of an automobile fuel tank. The fuel cutoff valve permits an outflow of fuel vapors in the tank during refueling and, restricts the fuel outflow when the fuel reaches a predetermined level.
2. Description of Related Art
FIG. 10
shows a structure of a prior art cutoff valve. A fuel cutoff valve
100
is mounted on an upper tank wall FTa of a fuel tank FT, and comprises a casing
102
, a cover
110
, a float
120
, and a spring
130
. The casing
102
comprises a top wall
103
, a side wall
104
of unitary construction having an outside edge formed of top wall
103
, and a base plate
105
attached to a bottom end of the side wall
104
so as to define an internal space forming a valve chest
102
S.
Within the valve chest
102
S is housed the float
120
having a valve portion
120
a
in its upper portion. This valve portion
120
a
opens and closes a connecting passage
103
d
connecting to the outside of the fuel tank FT. The float
120
is supported by the spring
130
arranged on the base plate
105
.
The cover
110
comprises a cover main body
112
for attaching to the casing
102
, a cover passage forming portion
114
, and a flange
115
, these elements being of unitary construction. The cover main body
112
has a mounting recess
114
a
formed therein, and fitting into an upper welding portion
103
b
of the top wall
103
of the casing
102
. An engaging protuberance
103
a
is formed at the top of the casing
102
, wherein the casing
102
and the cover
110
are assembled together by engagement with an engagement hole
112
a
of a support member of the cover
110
. The flange
115
is thermally welded to the upper tank wall FTa of the fuel tank FT via a joining end face
115
a.
To mount the fuel cutoff valve
100
on the upper tank wall FTa of the fuel tank FT, the float
120
and the spring
130
are installed within the casing
102
, which is then attached with the base plate
105
. The casing
102
is then installed in the cover
110
. Specifically, after installing an O-ring
140
in an annular recession (not shown) in the upper projecting portion
103
b
of the casing
102
, the upper projecting portion
103
b
is fitted into the mounting recess
114
a
of the cover
110
. The joining end face
115
a
of the flange
115
is heated with a thermal fusing plate (not shown), and the rim area of a tank fixation hole FTc of the fuel tank FT is also heated with a thermal fusing plate (not shown). The melted portions are then thermally welded together.
In the conventional art, the cover
110
and the upper tank wall Fta are both made of a polyethylene material in order to permit fusing of the cover
110
to the upper tank wall FTa. Thus, fuel vapor present within the fuel tank FT can permeate through the cover
110
, albeit in small quantities, and emitted into the atmosphere. From an environmental standpoint, it is desirable to reduce such fuel vapor emissions as much as possible.
SUMMARY OF THE INVENTION
The present invention provides a fuel cutoff valve that reduces the release of fuel vapors from fuel tanks into the atmosphere.
To solve this problem, an exemplary first embodiment of the present invention provides a fuel cutoff valve that is to be partly inserted in a fixation hole formed in an upper tank wall of a fuel tank, the upper tank wall being made of a first resin material. The fuel cutoff valve comprises a cover that includes a circular welding end constructed and arranged to be thermally welded to the upper tank wall to surround a circumference of the fixation hole, and a fuel conduit that is constructed and arranged to connect to outside. The fuel cutoff valve also comprises a casing that is made of a second resin material which has a greater fuel permeation-resistant property than the first resin material, the casing including a valve chest that is constructed and arranged to connect the fuel tank to the fuel conduit. A valve body is positioned in the valve chest to open and close the fuel conduit according to a level of a liquid fuel in the fuel tank. The cover is made of a third resin material containing the first and second resin material such that the first material is dispersed in a matrix of the second resin material.
The fuel cutoff valve is mounted on the top wall of the fuel tank. When the level of fuel rises as the tank is refueled, fuel vapor present within the fuel tank flows to the outside (a canister) through a connecting passage. When the fuel in the fuel tank reaches a predetermined level, the increased buoyant force on the float causes it to rise, blocking the connecting passage and preventing the fuel from flowing out of the fuel tank.
The cover of the fuel cutoff valve is made of a matrix of a second resin having excellent resistance to permeation by fuel, and contains added thereto as a dispersed phase, the same first resin material used for the fuel tank. Since the cover is made of a matrix of the second resin, emission of fuel vapor into the atmosphere through permeation through the cover is prevented. Since the cover also contains the first resin material as a dispersed phase, the cover can be welded to the upper tank wall, which is made of the same resin material as the dispersed phase.
Thus, when the fuel cutoff valve is installed on the upper tank wall, by welding the annular welding portion of the cover to the upper tank wall, the fixation hole is blocked to seal the tank interior from the outside. Therefore, emission of fuel vapor into the atmosphere from the highly fuel permeation-resistant cover can be prevented.
In a preferred embodiment of the invention, the cover and casing are supported via a sealing member, thereby ensuring a good seal between the cover and the casing.
In another preferred embodiment, the casing is unified with the cover by means of welding. This permits dispensing of the seal member, thus reducing the number of parts required.
A second exemplary embodiment of the present invention provides a fuel cutoff valve that is to be partly inserted in a fixation hole formed in an upper tank wall of the fuel tank, the upper tank wall being made of a first resin material. The fuel cutoff valve comprises a casing that includes a tubular side wall to be inserted in the fixation hole, a top wall to be integrally formed with the side wall, and a flange formed along a periphery of the top wall so as to cover an outside periphery of the fixation hole. A fuel conduit is constructed and arranged to connect to an outside portion of the side wall and the top wall defining a valve chest. The fuel cutoff valve also comprises a float that is accommodated in the valve chest to open and close the fuel conduit according to a level of a liquid fuel in the fuel tank. The casing is made of a resin material containing the first resin material and a second resin material which has greater fuel permeation-resistant property than the first resin material. The resin material of the casing is made such that the first resin material is dispersed in a matrix of the second resin material.
The second exemplary embodiment also comprises a casing made of a cover and casing of unitary construction. The casing is made of a resin material having a matrix of the second resin material and containing the first resin material as a dispersed phase, thereby reducing the number of parts required.
In a preferred embodiment of the fuel cutoff valve, the cut off valve comprises a weld fixing member fixed to the cover, the weld fixing member being made of the first resin material and having a weld fixing end welded to the upper tank wall integrally with the annular welding end of the cover. According to this embodiment, in cases where the first resin content of the co
Aoki Tomohide
Goto Hisatsugu
Kito Hiroaki
Nakagawa Masayuki
Michalsky Gerald A.
Toyoda Gosei Co,., Ltd.
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