Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
2000-12-21
2002-07-30
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C137S202000, C137S043000
Reexamination Certificate
active
06425379
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 11-369719 filed on Dec. 27, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an evaporative emission control system that prevents fuel vapors in a vehicular fuel tank from being discharged into the atmosphere and, more particularly, to an evaporative emission control system that prevents fuel from being transferred to a canister through a vapor vent line when the fuel tank is filled up and prevents fuel from flowing out of the tank when the vehicle inclines or rolls over.
2. Discussion of Related Art
A vehicular fuel tank is provided with a liquid level sensing valve, a fuel cut valve and the like. The liquid level sensing valve is adapted to close a vapor vent line when the tank is filled up. The fuel cut valve is adapted to close an evaporation line to prevent fuel from flowing out of the line, for example, when the vehicle inclines or rolls over. Each of these valves includes a float that vertically moves in accordance with the liquid level of the fuel.
Hereinafter, one example of evaporative emission control systems as part of the related art will be described with reference to
FIG. 1. A
valve casing
4
incorporating a liquid level sensing valve
2
and a fuel cut valve
3
formed as a unit is mounted on the fuel tank
1
. The valve casing
4
is composed of a lower valve casing
4
A and an upper valve casing
4
B disposed above the lower valve casing
4
A. A liquid level sensing float
5
and a fuel cut float
6
are disposed in the lower valve casing
4
A.
A valve portion
7
is provided on an upper surface of the liquid level sensing float
5
. Also, a valve portion
8
is provided by an upper portion of the fuel cut float
6
. Valve ports
9
,
10
are formed between the lower valve casing
4
A and the upper valve casing
4
B. The valve port
9
is opened and closed by the valve portion
7
, and the valve port
10
is opened and closed by the valve portion
8
. The upper valve casing
4
B is provided with a vent conduit
11
, which communicates with the valve port
9
through a space
12
. The space
12
also communicates with the valve port
10
through a conduit
13
.
The operation of the evaporative emission control system of the related art shown in
FIG. 1
will be now described.
If the pressure of fuel vapors in the fuel tank
1
becomes high during refueling, fuel vapors flow through the valve port
9
formed in the valve casing
4
, and are discharged into a canister (not shown), an intake pipe (not shown) and the like through the vent conduit
11
, as indicated by arrow P in FIG.
1
.
If the liquid level of the fuel in the fuel tank
1
is elevated, the liquid level sensing float
5
rises and the valve body
7
closes the valve port
9
. This prevents fuel from being directly fed to the canister.
If the pressure of fuel vapors in the fuel tank
1
remains high during normal operations, the liquid level sensing float
5
sticks to the valve port
9
. In this case, since the vent conduit
11
remains closed, it is necessary to reduce the pressure in the fuel tank
1
. To this end, the pressure is released through the valve port of the fuel cut valve
23
so that the liquid level sensing float falls because of its own weight.
If the vehicle inclines by a large degree or rolls over, a large amount of fuel in the fuel tank
1
may flow towards the canister through the valve port
10
and the conduit
13
. However, when the vehicle inclines by a large degree or rolls over, the fuel cut float
6
rises and the valve body
8
closes the valve port
10
, whereby fuel is prevented from flowing out.
In the aforementioned structure as shown in
FIG. 1
, the liquid level sensing float
5
and the fuel cut float
6
are disposed in the same valve casing
4
. However, other structures are also known in which the liquid level sensing float and the fuel cut float are individually disposed in separate valve casings.
Another example of evaporative emission control systems as part of the related art will be described with reference to
FIG. 2. A
liquid level sensing valve
22
and a fuel cut valve
23
are separately mounted on a fuel tank
21
. A valve casing
24
of the liquid level sensing valve
22
is formed with a vent conduit
25
, and a valve casing
26
of the fuel cut valve
23
is formed with a conduit
27
. A space
28
is formed in the valve casing
24
of the liquid level sensing valve
22
. A connection port
29
that extends from the space
28
is connected to the conduit
27
by means of a hose
30
.
The example shown in
FIG. 2
also performs substantially the same operation as the example shown in FIG.
1
. That is, if the liquid level of fuel in the fuel tank
21
becomes high, the liquid level sensing valve
22
closes the vent conduit
25
. This prevents fuel from being directly fed to the canister and the like.
If the pressure of fuel vapors in the fuel tank
21
remains high during normal operations, the float of the liquid level sensing valve
22
sticks to the valve port, and the vent conduit
25
remains closed. Therefore, it is necessary to reduce the pressure in the fuel tank
21
. To this end, the pressure in the fuel tank
21
is released through the valve port of the fuel cut valve
23
, so that the float of the liquid level sensing valve
22
falls because of its own weight.
If the vehicle inclines by a large extent or rolls over, a large amount of fuel in the fuel tank
21
may flow towards the canister through the valve port of the fuel cut valve
23
and the conduit
27
. However, when the vehicle inclines by a large degree or rolls over, the float of the fuel cut valve
23
rises and the valve port is closed, whereby fuel is prevented from flowing out.
However, the aforementioned evaporative emission control systems as part of the related art have the following disadvantages.
First of all, since the space
12
,
28
is directly connected to the vent conduit
11
,
25
with no intervening member therebetween, the fuel that has leaked out from the valve port
9
due to vibration of the vehicle, or the like, may be transferred toward the canister and degrade the canister.
Furthermore, the valve port
9
may be directly exposed to the fuel in the fuel tank, and therefore the fuel is more likely to leak through the valve port
9
.
With regard to the structure in which the connection port
29
of the liquid level sensing valve
22
and the conduit
27
of the fuel cut valve
23
are connected with each other by the hose
30
, the connecting operation cannot be accomplished in a simple manner. It thus takes a lot of time and labor to provide the system as shown in
FIG. 2
, while requiring many types of parts or components.
SUMMARY OF THE INVENTION
It is thus an object of the invention to reduce or eliminate the disadvantages of the evaporative emission control systems as the related art, and to provide an evaporative emission control system that achieves reduction of the amount of leaking fuel, simplified procedure of mounting or connecting pipes, and reduction of the number of types of required parts or components.
To accomplish the above object, an evaporative emission control system is provided according to the present invention, which includes: an upper valve casing defining a vent conduit; a lower valve casing disposed under the upper valve casing; a float disposed within the lower valve casing, the float being vertically movable depending upon a liquid level of fuel in a fuel tank, the float including a valve portion that faces the upper valve casing; a valve port provided between the upper valve casing and the lower valve casing, the valve port being opened and closed by the valve portion of the float, the upper valve casing defining a space between the vent conduit and the valve port; and a flow restricting device disposed in the space of the upper valve casing so as to obstruct flow of fuel from the valve port to the v
Masuda Hidemi
Shimamura Hiroshi
Sugimura Norikazu
Suguira Koji
Kyosan Denki Co. Ltd.
Moulis Thomas N.
Oliff & Berridg,e PLC
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