Fluid handling – Control by change of position or inertia of system – Vent opening or closing on tipping container
Reexamination Certificate
2001-08-21
2002-12-17
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Control by change of position or inertia of system
Vent opening or closing on tipping container
C137S202000
Reexamination Certificate
active
06494227
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a valve for a vehicle fuel tank, more particularly to an anti-spill valve for installation in the top of the fuel tank of a vehicle, particularly an automobile, for preventing pressure buildup in the tank during normal operation by allowing internal tank pressure to escape to the exterior and for preventing spillage of gasoline to the exterior when the vehicle suddenly accelerates, turns sharply or overturns.
2. Description of the Prior Art
FIG. 20
is a cross-sectional diagram of a prior art valve, and
FIG. 21
shows the valve of
FIG. 20
turned sideways. In
FIGS. 20 and 21
, reference numeral
1
denotes a housing formed of synthetic resin, comprising a housing unit
2
and a detachable cap
7
. The housing unit
2
has a passage
3
a
that communicates with the outside, provided in the center of the housing unit
2
. Going toward the interior of the housing unit
2
, the passage
3
a
expands into a conical valve seat
3
b
formed in a round ceiling
3
. From the outer edge of the ceiling
3
, a cylindrical side wall
4
extends downward. The side wall
4
is provided with a plurality of holes
4
a
, a plurality of claws
4
b
around the lower circumference that are thicker toward the upper end, and guide ribs
4
c
used to guide a float
11
(described below). The guide ribs
4
c
are of equal height and are disposed axially at set intervals around the inside of the side wall
4
. From the center of the ceiling
3
, a connecting pipe
5
having a central passage
5
a
that communicates with the passage
3
a
extends radially out past the side wall
4
. An annular mounting member
6
provided on the outside of the side wall
4
is used to mount the housing unit
2
on a fuel tank.
The cap
7
comprises a cylindrical side wall
8
with radial engaging holes
8
a
that correspond to the claws
4
b
on the side wall
4
and float guide ribs
8
b
disposed axially at set intervals around the inside surface, and a bottom
9
that closes the lower end of the side wall
8
. The bottom
9
has a plurality of vertical holes
9
a
that enable the bottom
9
to function as a filter. Reference numeral
11
denotes a float housed in the housing
1
. The float
11
is cylindrical in shape and formed of synthetic resin. The lower end of the float
11
has an annular concave portion
12
, and is provided with a plurality of vertical through holes
13
that communicate with the concave portion
12
, and a valve head
14
that projects up from the top of the float and operates to open and close the passage
3
a
by separation from and contact with the valve seat
3
b
. A coil spring
21
is disposed between the housing bottom
9
and the float
11
to help urge the float
11
upwardly.
Operation of the valve will now be described. The valve is normally mounted on a fuel tank (not shown) with the housing
1
oriented vertically, as shown in FIG.
20
. In this state, the float
11
descends under its own weight against the force of the coil spring
21
, separating the valve head
14
from the valve seat
3
b
and opening the passage
3
a
. Gasoline vapor formed in the fuel tank is therefore able to flow out via the holes
4
a
and
9
a
, the space between the side wall
4
and the float
11
, and the passages
3
a
and
5
a
, preventing the pressure inside the fuel tank becoming elevated.
Although a buoyant force acts on the float
11
when gasoline enters the housing
1
through the holes
9
a
owing to a large inertial force produced by rapid acceleration or sharp turning of the vehicle, this force alone is not strong enough to raise the float
11
since the specific gravity of the float
11
is greater than that of the gasoline. However, the buoyant force combined with the weak force of the spring
21
acting upwardly on the float is sufficient to raise the float and bring the valve head
14
into close contact with the valve seat
3
b
, closing the passage
3
a
and thereby preventing gasoline from flowing out of the fuel tank. When the vehicle returns to a normal state and gasoline in the housing
1
flows back through the holes
9
a
into the fuel tank, under its own weight the float
11
descends, compressing the spring
21
, whereby the valve head
14
separates from the valve seat
3
b
, opening the passage
3
a
. If the vehicle should turn over onto its side, the valve will also be turned sideways, as shown in
FIG. 21
, and the force of the coil spring
21
will move the float
11
in the direction of the passage
3
a
until the passage
3
a
is closed by the abutment of the valve head
14
against the valve seat
3
b
, thus preventing gasoline in the fuel tank spilling to the outside.
In the prior art valve, a clearance h is provided between the guide ribs
4
c
and the float
11
to allow the float
11
to move smoothly. Therefore, if the vehicle falls on its side, as shown in
FIG. 21
, the center axis of the valve head
14
(the axis of the float
11
) is subjected to a parallel displacement down from the axis of the passage
3
a
by the amount of the clearance h. In this state, even if the float
11
is moved with the intention of closing the passage
3
a
with the valve head
14
, the valve head
14
will contact the lower sloping face of the conical valve seat
3
b.
In order to have the valve head
14
close the passage
3
a
, a force is required that lifts the valve head
14
. This force is provided by the coil spring
21
, but the lifting force is reduced by the high frictional resistance that exists between the sloping portion of the valve seat
3
b
and the valve head
14
. Since this can prevent the passage
3
a
being promptly and fully closed by the valve head
14
, gasoline can leak from the fuel tank.
This invention was accomplished in response to the foregoing circumstances and has as an object to provide a valve that, even when turned sideways, can suppress leakage of fuel to the exterior by promptly closing a passage that communicates with the outside.
SUMMARY OF THE INVENTION
For achieving the aforesaid object, the invention provides a valve comprising a housing having an outside-communicating passage and a float provided in the housing that opens and closes the passage by moving axially along the housing, the valve being provided with a float guide means that guides the float to close the passage by means of a gap formed between an inner surface of the housing and an outer surface of the float that increases in size with increasing distance from the passage.
The guide means comprises a float tapered portion provided on the cuter surface of the float that tapers in with increasing distance from the passage, the tapered portion being provided from the outer peripheral edge at the passage end of the float, to where a plane that passes through the center of gravity of the float and is orthogonal to the float axis, intersects the outer surface of the float. The guide means can also be provided on the inner surface of the housing as a housing tapered portion that narrows the housing toward the passage end.
In another aspect of the invention, the float is provided with a pivot support portion at a junction between a float cylindrical surface and a float tapered portion, that is located at a point on the side face of the float intersected by a plane that passes through the center of gravity of the float and is orthogonal to the float axis, and the float tapered portion tapers in away from the passage end. The pivot support portion can be located at a junction between first and second float tapered portions constituting the float tapered portion.
The pivot support portion can be provided as a portion that extends around the whole peripheral surface, or it can be provided as a plurality of sections. When it is provided as a plurality of sections, a plurality of grooves can be used to divide the pivot support portion into a plurality of pivot support portions on the outer surface of the float. Alternatively, the pivot support portion can be divided into a plurality of pivot support portion
Aoyama Taiki
Hattori Toshio
Michalsky Gerald A.
Nifco Inc.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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