GB2245259A

GB2245259A - A fuel tank arrangement and cap

Info

Publication number: GB2245259A
Application number: GB9013655A
Authority: GB
Inventors: Ronald Pardy
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1990-06-19
Filing date: 1990-06-19
Publication date: 1992-01-02
Anticipated expiration: 2010-06-19
Also published as: GB2245259B; GB9013655D0

Abstract

To prevent surging fuel wetting the fuel cap, in a fuel tank 10 the fuel cap 16 seals the tank both above and below the position at which a fuel level sensing tube 14 communicates with the filler neck 12. One seal 20 seals an air volume (30 Figs 2, 3) at the top of the filler neck and a second seal 18 seals an air volume in the top of the sensing tube. <IMAGE>

Description

A FUEL TANK ARRANGEMENT This invention relates to a fuel tank arrangement, and in particular to a fuel tank arrangement for use on a motor vehicle.

It is conventional for fuel tanks to have a fuel filler neck and a filler cap at the top of the neck to close the filler pipe.

It is also known to provide a separate sensing tube which extends from the air space at the top of the tank to a position close to the mouth of the filler neck. The position of the lower end of this sensing tube controls the height to which the tank can be filled with fuel.

The sensing pipe generally enters the filler neck at a point below the position of the cap/neck seal and is directed across the filler neck so that any liquid fuel passing up the sensing pipe will not be directed out of the filler neck. There is a likelihood that, when the tank is closed and the vehicle is running, fuel will surge up the filler neck to wet the bottom end of the cap, displacing a corresponding volume of air down the sensing tube. This may result in the bottom of the cap being wet when the cap is removed for refuelling, and the fuel from the bottom of the cap may then drip on the person refuelling the car.

This is a particular concern with diesel fuel, but applies to petrol and other liquid fuels also.

It is an object of this invention to prevent this occurring.

According to the invention, there is provided a fuel tank arrangement comprising a fuel tank having a filler neck, a filler cap for closing the mouth of the filler neck and a fuel line sensing tube which provides a communication between the internal volume of the tank and the filler neck at a position adjacent the mouth of the neck, wherein the cap is constructed so that insertion of the cap in the neck seals the filler neck at a position below the entry to the neck of the sensing tube, and also seals the upper end of the sensing tube.

Because the effect of this will be to close the filler neck below the sensing tube, the sealing of the filler neck will trap a fixed volume of air. If the body of fuel in the tank is subjected to an acceleration which will drive it up the filler neck, then the fuel surface will only reach so far up the filler neck before the contained volume of air can be compressed no further. As a result, the fuel itself will not reach the cap and will not wet the cap.

The sensing tube preferably enters the filler neck through a branch passage located a short distance below the mouth of the neck.

The cap preferably has a primary and a secondary seal; the primary seal closing the mouth of the filler neck, and the secondary seal sealing against a secondary valve seat formed in the filler neck below the entry of the sensing tube.

The invention also extends to a fuel filler cap having a primary and a secondary seal, the primary seal adapted to form a seal at the mouth of the filler neck, and the secondary seal adapted to form a seal at a point within the filler neck.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a section through a fuel tank arrangement in accordance with the invention, with the tank empty and the cap removed; Figure 2 shows the same arrangement of Figure 1, but with the tank filled with petrol; and Figure 3 shows the same tank again, this time showing the tank having been subjected to an acceleration.

The tank shown in Fig 1 is a blow-moulded petrol tank for a vehicle. The invention could however be equally applied to a diesel fuel tank or indeed to any other tank for containing liquid fuel. The tank has a main tank body 10 in which fuel will be contained, a filler neck 12 and a sensing tube 14. In addition to these components, the tank will also have other components associated with it, such as a vapour vent system, a fuel outlet to the engine and a fuel level sensing device within the tank. These components however will be conventional in form, are not shown in the drawings and will not be further described here.

A fuel cap 16 is arranged to fit into the top of the filler neck 12. The cap 16 has a first sealing surface at 18 and a second sealing surface at 20. The surface 18 will seal against the rim 22 of the filler neck, and the surface 20 will seal against an internal seat 24.

The sensing tube 14 has a lower end which projects into the tank 10 at a position close to the middle of the tank, and the position of the lower end of the sensing tube will determine the maximum height to which the tank can be filled. Once the lower end of the sensing tube is submerged, a volume of air will be trapped between the roof of the tank and the surface of the fuel. Further filling of the tank will result in the fuel level rising both in the filler neck and in the sensing tube until the position of Fig 2 is reached. As the fuel level rises in the filler neck, so this provides a back pressure which will act te shut off fuel feed from a fuel filler nozzle.

While the tank is being filled, air will be expelled from the tank both via the filler neck 12, past the filler nozzle, and via the sensing tube 14, the top end of which leads into the top end of the filler neck 12 at 26.

When the tank is filled with petrol 28, and the cap is closed the position of Fig 2 will be taken up. Because the sealing surface 20 of the cap seals on the seat 24, a closed volume of air will be trapped at 30 in the filler neck. The top end of the sensing pipe 14 which opens into the filler neck at 26, will also be closed by the seal formed between the surface 18 and the rim 22.

The fuel level shown in Fig 2 is of course shown whilst the vehicle in which the tank is mounted is stationary. When the vehicle moves, the fuel in the tank will also move.

Under an extreme acceleration such as might occur for example during cornering, the fuel may all rush to one side of the tank in the manner shown in Fig 3. However, when this happens, because of the presence of the seal at 20, 24, the trapped volume of air at 30 will prevent the liquid fuel reaching the cap 16. Therefore, whatever motion the fuel tank undergoes, the inner surfaces of the cap will remain unwetted by the fuel and therefore when the cap is removed so that re-fuelling can occur, there will be no risk of fuel dripping from the cap when it is removed.

This, therefore, provides a simple way of avoiding the annoyance resulting from a dripping fuel cap.

Claims

1. A fuel tank arrangement comprising a fuel tank having a filler neck, a filler cap for closing the mouth of the filler neck and a fuel line sensing tube which provides a communication between the internal volume of the tank and the filler neck at a position adjacent the mouth of the neck, wherein the cap is constructed so that insertion of the cap in the neck seals the filler neck at a position below the entry to the neck of the sensing tube, and also seals the upper end of the sensing tube.

2. A fuel tank arrangement as claimed in Claim 1, wherein the sensing tube enters the filler neck through a branch passage located a short distance below the mouth of the neck.

3. A fuel tank arrangement as claimed in Claim 1 or Claim 2, wherein the cap has a primary and a secondary seal; the primary seal closing the mouth of the filler neck, and the secondary seal sealing against a secondary valve seat formed in the filler neck below the entry of the sensing tube.

4. A fuel tank arrangement substantially as herein described with reference to the accompanying drawings.

5. A fuel filler cap having a primary and a secondary seal, the primary seal adapted to form a seal at the mouth of the filler neck, and the secondary seal adapted to form a seal at a point within the filler neck.

6. A fuel filler cap substantially as herein described with reference to the accompanying drawings.