GB2254125A

GB2254125A - Valve for a motor vehicle fuel tank vent passage.

Info

Publication number: GB2254125A
Application number: GB9106212A
Authority: GB
Inventors: Ronald Pardy; Steven Shortis
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1991-03-23
Filing date: 1991-03-23
Publication date: 1992-09-30
Also published as: GB9106212D0

Abstract

A motor vehicle fuel tank 10 has a fuel level sender mechanism 24 and a vapour vent passage 20. A valve 22 located in the vent passage includes a valve member 54 which closes the vent passage, and a pair of electrical contacts 64, 66, under conditions of extreme acceleration and in the event of a roll over. Closing of the electrical contacts results in the fuel level sender mechanism being isolated from a fuel gauge 42. <IMAGE>

Description

VALVE This invention relates to a valve for use in conjunction with a motor vehicle fuel tank.

Motor vehicle fuel tanks conventionally have a vapour vent passage which allows fuel vapour to escape from the tank to prevent excess pressure build up in the tank. The passage opens into the top, vapour space of the tank and provides a path along which vapour can escape to atmosphere.

In order to avoid liquid fuel flowing out of this passage in the event of the car turning over in an accident, and to prevent liquid surges flowing along the vent passage during sudden acceleration or cornering, it is conventional to include a so-called "roll-over" valve in the vent passage.

This valve closes the passage if the valve body itself is inverted or if the body is subjected to acceleration forces.

Fuel tanks also include fuel level sender mechanisms so that a signal can be produced which will inform the driver about the level of fuel in the tank. However with a conventional fuel sender where a float on the end of a pivoted arm floats on the fuel surface, movement of the float arm can be erratic when the car is subjected to extreme lateral accelerations or decelerations, either on braking, acceleration or cornering. It is desirable to be able to disconnect the signal from the fuel sender from a fuel gauge at such times.

According to the present invention, there is provided a fuel tank installation for a motor vehicle, the installation comprising a fuel tank, a vent passage leading from the tank, a fuel sender mechanism in the tank and a roll-over valve in the vent passage, the valve being arranged so that a valve member closes the vent passage in the event that the vehicle rolls over, the valve also including a pair of electrical contacts arranged so that movement of the valve member either opens or closes the contacts, and wherein the contacts are part of an electrical circuit connecting the fuel sender to a fuel gauge.

Preferably the roll-over valve and the electrical contacts are contained within a single housing, with the electrical contacts being isolated from the fuel passage by means of a flexible diaphragm which seals on the valve member.

Alternatively, the electrical contacts could be enclosed in a separate sealed chamber.

The roll-over valve preferably includes a valve seat arranged so that the valve member is normally biased away from the seat by gravity, but is urged so as to block the seat in the event of roll-over, or during cornering manoeuvres.

The housing may be mounted directly on the top face of a fuel tank, or may be connected in a fuel vent passage outside the fuel tank.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a fuel tank installation in accordance with the invention; and Figure 2 is a cross section through a valve for use in the invention.

Figure 1 shows a fuel tank 10 containing fuel 12. The fuel level is indicated at 14. The tank 10 is filled through a filler neck 16 which will be closed by a conventional cap (not shown).

The vapour space 18 above the fuel in the tank is vented to atmosphere via a vent passage 20. This vent passage passes through a valve indicated at 22. The vent passage through this valve is normally open as will be described with reference to Figure 2, but can be closed if the vehicle rolls over.

Inside the tank is a fuel level sender mechanism 24 which includes a float 26 mounted on the end of a pivoted arm 28.

As the level 14 of the fuel changes, the position of the float 26 will change and the sender mechanism 24 will produce an electrical signal in accordance with the angular position of the float arm 28 relative to the mechanism.

The mechanism 24 is supported within the tank on a support 30, and the signal output is produced via a pair of conductors 32, 34. This signal is fed to a switch unit 36 and from the switch unit via a pair of conductors 38, 40 to a gauge 42 which will be located on the instrument panel of the car.

The switch unit 36 is connected to the valve 22 by a further pair of conductors 44, 46.

The valve 22 is shown in more detail in Figure 2. The valve has an inlet connection 48 and an outlet connection 50, both of which are connected to the vent passage 20.

Within the housing of the valve 22 there is a valve seat 52, and a valve member 54 has a projection 56 which passes through the seat 52 and can move to close the seat 52. The valve member is associated with a ball 58 which, when the vehicle in which the valve is installed turns over, will provide an inertial force to close the valve member 54 onto the seat 52 to block the passage 20. The ball 58 is located within a cage part 54a of the valve member 54 and is associated with an inclined bottom surface 60 of the housing 22 to obtain the desired movement of the valve member in the event of the vehicle being subjected to an extreme lateral acceleration.

At the top of the valve housing 22 there is a chamber 62 which is separated from the lower half of the valve by a diaphragm 64. The diaphragm 64 is sealed around the valve member projection 56 so that no fuel or fuel vapour from the passage 20 can penetrate into the space 62. The diaphragm is however flexible so that it does not restrict the movement of the valve member 54.

In the chamber 62 there are two electrical contacts 64, 66 which are shown in the open condition. This is the normal condition of the valve. However in the event of a condition which will cause the valve member to move, the projection 56 will cause the contacts 64, 66 to close.

In operation, the valve 22 will normally take up the position shown in Figure 2 where fuel vapour can flow through the inlet 48, through the valve seat 52 and out through the outlet 50. The vent passage 20 will thus be open. Additionally the contacts 64, 66 will be open, and as a result the switch unit 36 will be closed so that signals from the sender unit 24 can be passed directly to the gauge 42.

However if the vehicle in which the fuel tank is mounted undergoes severe acceleration forces in any direction, then the ball 58 will ride up the ramp formed by the inclined bottom surface 60 to both close the valve member 54 onto the seat 52 and to bring the contacts 64, 66 together. As a result, whilst this acceleration persists, the vent passage 20 will be closed, and the closing of the contacts will cause a condition to arise in the switch unit 36 which causes the switch to open and temporarily isolate the gauge 42 from the sender mechanism 24. It is important to note that when undergoing severe acceleration, the liquid level in the tank will not be level as indicated in Figure 1, but will be forced by the acceleration forces to one side of the tank. As a result the position of the float 26 will temporarily not be representative of the quantity of fuel left in the tank.

However as soon as the acceleration force is removed, the ball 58 will return to the position shown in Figure 2, the valve seat 52 will be opened and the electrical contacts 64, 66 will open. This will result in the switch 36 closing again so that communication is restored between the sender unit 24 and the gauge 42.

By combining the roll-over valve and the fuel sender deactivation circuit into one housing, a considerable space saving and complexity reduction is achieved.

The invention can in principle be applied to any construction of roll-over valve, and the electrical contacts 64, 66 can be provided in any convenient way. In one example, the contacts may be sealed in a mercury tilt switch but other types of switch arrangement will be possible.

Claims

1. A fuel tank installation for a motor vehicle, the installation comprising a fuel tank, a vent passage leading from the tank, a fuel sender mechanism in the tank and a roll-over valve in the vent passage, the valve being arranged so that a valve member closes the vent passage in the event that the vehicle rolls over, the valve also including a pair of electrical contacts arranged so that movement of the valve member either opens or closes the contacts, and wherein the contacts are part of an electrical circuit connecting the fuel sender to a fuel gauge.

2. A fuel tank installation as claimed in Claim 1, wherein the roll-over valve and the electrical contacts are contained within a single housing, with the electrical contacts being isolated from the fuel passage by means of a flexible diaphragm which seals on the valve member.

3. A fuel tank installation as claimed in Claim 1, wherein the electrical contacts are enclosed in a sealed chamber separated from the vent passage.

4. A fuel tank installation as claimed in any preceding claim, wherein the roll-over valve includes a valve seat arranged so that the valve member is normally biased away from the seat by gravity, but is urged so as to block the seat in the event of roll-over.

5. A fuel tank installation as claimed in any preceding claim, wherein the housing is mounted directly on the top face of the fuel tank.

6. A fuel tank installation substantially as herein described with reference to the accompanying drawing.

7. A valve having a fluid passage therethrough, a valve member which can move between a first position in which the passage is open and a second position in which the passage is closed, and a pair of electrical contacts which are moved between opened and closed positions by movement of the valve member between the first and second positions.

8. A valve substantially as herein described with reference to Figure 2 of the accompanying drawings.