Fluid handling – Diverse fluid containing pressure systems – Fluid separating traps or vents
Reexamination Certificate
2000-01-31
2001-09-11
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Fluid separating traps or vents
C137S043000
Reexamination Certificate
active
06286539
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel cutoff valve mounted on an upper wall of a fuel tank to open and close a connection conduit, which connects the inside of the fuel tank with the outside.
2. Description of the Related Art
FIG. 5
shows a prior art fuel cutoff valve
100
having a known structure disclosed in U.S. Pat. No. 5,404,907. The fuel cutoff valve
100
is mounted on an upper tank wall FTa of a fuel tank FT, and includes a casing
102
, a cover
110
, a float
120
, and a spring (not shown). The casing
102
has an upper wall
103
, a side wall
104
that extends from the outer circumference of the upper wall
103
and is integrally molded with the upper wall
103
, and a bottom plate
105
that is attached to a lower end of the side wall
104
. An inner space of the casing
102
forms a valve chest
1028
.
The float
120
having a valve element
120
a
disposed on an upper wall thereof is accommodated in the valve chest
102
S. The valve element
120
a
opens and closes a connection conduit
103
d
that connects with inside of the fuel tank FT with outside. The float
120
is supported by the spring (not shown) mounted on the bottom plate
105
.
The cover
110
includes a cover main body
112
fixed to the casing
102
, a cover passage forming element
114
, and a flange
115
. These constituents of the cover
110
are integrally molded. The cover main body
112
has an attachment recess
114
a
, in which an upper projection element
103
b
of the upper wall
103
of the casing
102
is fitted. Engagement apertures
103
a
are formed in the upper wall of the casing
102
to receive engagement projections
112
a
formed on the cover
110
and fitted therein, so that the casing
102
is joined with the cover
110
. A join end
115
a
of the flange
115
is thermally welded to the upper tank wall FTa of the fuel tank FT.
In the fuel cutoff valve
100
of the above structure, in the course of fuel supply into the fuel tank FT, the fuel vapor in the fuel tank FT flows out to a canister (not shown) via a through hole
105
a
formed in the bottom plate
105
of the casing
102
, the valve chest
102
S, the connection conduit
103
d
, and a passage
114
b of the cover
110
. When the level of the liquid fuel in the fuel tank FT reaches a particular level FLI, the liquid fuel flows into the valve chest
102
S via the through hole
105
a
and gives the buoyancy to raise the float
120
. The rise of the float
120
causes the valve element
120
a
formed on the upper wall of the float
120
to close the connection conduit
103
d
, so as to prevent the fuel from flowing out of the fuel tank FT.
In the prior art fuel cutoff valve
100
, however, the joint of the casing
102
with the cover
110
is attained only through the engagement of the engagement projections
112
a
with the engagement apertures
103
a
and thereby readily becomes unsteady to make the casing
102
movable to the cover
110
. The cover
110
is made of polyethylene and is thermally welded to the fuel tank FT, which is also made of polyethylene, whereas the casing
102
is made of polyacetal having a smaller fuel swelling property than polyethylene, in order to ensure the high sealing properties. Namely the cover
110
and the casing
102
are made of different resin materials. When the casing
102
and the cover
110
swell in the liquid fuel in the fuel tank FT, the difference in swelling properties between the cover
110
and the casing
102
, which are joined with each other only through the engagement of the engagement apertures
103
a
with the engagement projections
112
a
, may cause the casing
102
to be movable against the cover
110
. Such unsteady joint undesirably lowers the mechanical strength of the fuel cutoff valve
100
against shocks and varies the opening and closing liquid levels of the fuel cutoff valve
100
. These lead to the unstable valve opening and closing properties.
SUMMARY OF THE INVENTION
The object of the present invention is thus to provide a fuel cutoff valve that does not move against an upper tank wall of a fuel tank even when swelling in a liquid fuel, but ensures stable valve opening and closing properties.
At least part of the above and the other related objects is attained by a fuel cutoff valve that is partly inserted in a fixation hole formed in an upper tank wall of a fuel tank, so as to be mounted on the upper tank wall. The fuel cutoff valve includes: a cover that is made of a first resin material, which enables the cover to be thermally welded to the upper tank wall, the cover including a circular welding end that is thermally welded to an upper surface of the upper tank wall to surround a circumference of the fixation hole, a fuel conduit that connects the fuel tank to outside, and a support member that is capable of being inserted into the fixation hole; a casing that is made of a second resin material, which has a smaller fuel swelling property than the first resin material, the casing having a valve chest that connects the fuel tank to a connection conduit; a valve member that is received in the valve chest to open and close the connection conduit according to a level of a liquid fuel in the fuel tank; mating engagement elements that are respectively formed on the support member and the casing and engage with each other, so as to join the support member with the casing; and a holder unit that is formed on the casing and is in contact with the support member, so as to be supported by the cover, the holder unit being arranged to increase a supporting force against the support member when the support member swells in the liquid fuel.
In the fuel cutoff valve of the present invention, the casing has the valve chest that connects with the fuel tank. The valve member received in the valve chest varies the buoyancy according to the level of the liquid fuel in the fuel tank, so as to ascend and descend in the valve chest. The valve member accordingly opens and closes the connection conduit and effectively prevents the fuel from flowing out of the fuel tank. In the fuel cutoff valve of the present invention, the cover is made of a resin material that enables the cover to be thermally welded to an upper wall of the fuel tank. The fuel cutoff valve of this configuration is readily mounted on the upper wall of the fuel tank without using any special fastening members.
Both the cover and the casing swell in the liquid fuel. The cover is made of the first resin material, which has the greater fuel swelling property than the second resin material that is applied for the casing. The cover is accordingly expanded to a greater degree than the casing. The holder unit disposed on the casing increases the supporting force against the support member of the cover with the swell of the cover. The casing is thus securely held by the cover via the holder unit and is not movable against the cover under the swelling condition of the cover. The fuel cutoff valve of the present invention accordingly attains the stable valve opening and closing properties without any possible troubles due to the unsteady joint, for example, a lowered mechanical strength against shocks or a variation in opening and closing liquid levels of the fuel cutoff valve.
In accordance with one preferable application of the present invention, the holder unit has a holder that is protruded from a side wall of the casing, so that a lower end of the support member is held by the side wall of the casing.
In this preferable application, the casing has an upper protrusion that forms part of the connection conduit, and the cover has a mating recess, in which the upper protrusion is fitted. A sealing member is interposed between the upper protrusion and the mating recess. This arrangement ensures the high sealing properties.
In one preferable embodiment, the mating engagement elements include an engagement projection that is protruded from the casing, and an engagement aperture that is formed on the support member and receives the engagement projection fitted therei
Nakagawa Masayuki
Nishi Hiroshi
Sugizaki Tomohiro
Michalsky Gerald A.
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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