Fluid handling – Systems – System with plural openings – one a gas vent or access opening
Reexamination Certificate
2000-09-14
2001-09-18
Chambers, A. Michael (Department: 3753)
Fluid handling
Systems
System with plural openings, one a gas vent or access opening
C123S516000, C123S520000
Reexamination Certificate
active
06289929
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims benefit of priority of Japanese Patent Application No. Hei-11-279064 filed on Sep. 30, 1999, the content of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure control valve for controlling a pressure in a fuel tank, such as a fuel tank of an automotive vehicle.
2. Description of Related Art
A pressure control valve is disposed in a passage connecting a fuel tank of an automotive vehicle to an atmospheric pressure to prevent excessive negative pressure from being developed in the fuel tank. The atmospheric pressure is supplied, for example, from a drain port of a canister that temporarily holds fuel vapor generated in the fuel tank and suppresses fuel vapor exhaust from the fuel tank.
An example of such a pressure control valve is disclosed in JP-A-8-121619. The control valve includes a wall separating a valve chamber from a canister port and a valve body disposed in the valve chamber. A through-hole formed in the separating wall is opened or closed by the valve body according to a difference between the fuel tank pressure and an atmospheric pressure. The valve body is biased by a spring in a direction to close the through-hole. The valve chamber always communicates with a fuel tank port, and a canister inner pressure is applied to a front surface of the valve body while a fuel tank inner pressure is applied to a back surface of the valve body. When the fuel tank inner pressure decreases to a predetermined level, the valve body opens the through-hole to introduce atmospheric pressure into the fuel tank. The valve body is formed by connecting a dish-shaped metallic member to a rubber disc. A circular lip portion is formed on the rubber disc to tightly close the through-hole.
Another example of the valve device for preventing the fuel tank pressure from becoming excessively negative is disclosed in JP-A-6-50447. In this device, a hole communicating with atmosphere is formed in a top plate of a fuel tank cap, and the hole is usually closed by a valve body disposed inside the top plate. The valve body is biased by a spring in a direction to close the hole. When the fuel tank pressure decreases to a predetermined level, the valve body opens the hole against the biasing force of the spring to introduce the atmospheric pressure into the fuel tank. The valve body is composed of a cup-shaped rubber member having a circular sealing lip to tightly close the hole.
There is a problem in both of the conventional pressure control valves. When the atmospheric pressure is once introduced into the fuel tank through the open valve, the atmospheric pressure is immediately applied to the inner surface of the valve body. Accordingly, the open valve is instantly closed, and the negative pressure quickly develops in the fuel tank to open the valve again. This results in a vibrating operation of the valve between its closed and open positions with a short cyclic period. The vibrating operation of the valve generates vibrating noise.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved pressure control valve in which the valve vibration and the vibrating noise are prevented.
A pressure control valve having a first valve and a second valve is disposed in a passage connecting a fuel tank and a canister. The first valve opens to introduce an atmospheric pressure through the canister into the fuel tank when the fuel tank pressure becomes negative and lower than a predetermined level. The second valve opens to release the fuel tank pressure to the atmosphere through the canister when the fuel tank pressure becomes higher than a predetermined level.
The first valve is made of a rubber material partially reinforced by a metal disc, and includes a seal member and a diaphragm formed around the seal member. The atmospheric pressure is applied to a front surface of the first valve through the canister, while the fuel tank pressure is applied to a back surface through an orifice formed in the diaphragm. The first valve is normally biased to its closing position by a spring. When a vehicle stops and fuel temperature in the fuel tank drops, a negative pressure is developed in the fuel tank. At this time, the first valve opens to introduce the atmospheric pressure into the fuel tank, thereby alleviating the negative pressure in the fuel tank. Though the pressure in the fuel tank increases upon opening the first valve, the pressure applied to the back surface of the first valve does not immediately increase because that pressure is applied through the orifice having a small diameter. Accordingly, the first valve once opened does not close immediately. Thus, the first valve is prevented from being vibrated between its open and closed positions with a short cyclic time. The noise otherwise caused by such a vibration is prevented.
Alternatively, a magnet is used in place of the orifice to delay the closing operation of the first valve. The magnet is placed to face a moving core connected to the first valve to magnetically attract the moving core and thereby to restrict a quick closing movement of the first valve.
Preferably, an electromagnetic driver is connected to the first valve to move the first valve to its open position, irrespective of the pressure in the fuel tank. Upon energization of the electromagnetic driver, the first valve is forcibly open to make a bypass passage between the fuel tank and the atmosphere. The bypass passage is readily formed, when needed, without providing a separate device.
According to the present invention, the closing operation of the first valve once opened is delayed, and thereby the vibration and the vibrating noise of the first valve are prevented.
REFERENCES:
patent: 5234022 (1993-08-01), Harris
patent: 5429099 (1995-07-01), DeLand
patent: 5749349 (1998-05-01), Detweiler et al.
patent: 5853018 (1998-12-01), DeLand et al.
patent: 5941218 (1999-08-01), DeLand et al.
patent: 6050447 (1994-02-01), None
patent: U-62-62077 (1994-09-01), None
patent: 8 121619 A (1996-05-01), None
patent: 8270515 (1996-10-01), None
Kobayashi Yasunori
Takeuchi Yukihiko
Chambers A. Michael
Denso Corporation
Nixon & Vanderhye PC
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