GB2308077A

GB2308077A - Fuel tank filter

Info

Publication number: GB2308077A
Application number: GB9525677A
Authority: GB
Inventors: Donald Richard Grant Bacon; Robert John Byrne
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1995-12-15
Filing date: 1995-12-15
Publication date: 1997-06-18
Also published as: GB9525677D0

Description

FUEL FILTER This specification relates to a fuel filter for use as an in-tank fuel filter for a motor vehicle fuel system.

A motor vehicle fuel system comprises a fuel tank which holds a reservoir of fuel for the engine, a fuel pump for pumping fuel from the tank to the engine and a fuel line between the pump and the lowermost part of the fuel tank, through which fuel is drawn by the pump. In many cases, the fuel pump is located inside the fuel tank, but the present invention is not limited to such a construction.

It is very important to ensure that the fuel pump pumps only clean fuel to the engine, and to this end it is conventional to incorporate a filter between the fuel in the tank and the pump to prevent any foreign matter from the tank from entering the pump.

The fuel line should communicate with the tank at the base of the tank, so that fuel will continue to be drawn up by the pump, even when the tank is nearly empty.

Because of changes in their internal volume, fuel tanks are rarely completely stable in use. The walls of the tank are liable to flex as a result of different internal pressures, and different volumes of fuel within the tank.

This is particularly noticeable with tanks made of moulded plastics material.

According to the present invention, there is provided an in-tank fuel filter having an annular pump connector for connecting the filter to a fuel line, a filter sock sealed to the pump connector so that, in use, the pump communicates with the inside of the filter sock, and a stuffer arm mounted at one end on the connector and extending therefrom inside the sock to spread the sock, the stuffer arm having a shank extending from the connector in a direction which, in use, will have a component extending towards the bottom of a fuel tank in which the filter is located, and a foot at the end of the stuffer arm end remote from the connector, which foot is connected to the shank by a hinge and is biased about the hinge axis in a direction such that, in use, the foot will lie flat against the tank floor.

The hinge can be a plastics membrane hinge, a hinge with a separate hinge pin or any other form of hinge.

The use of a hinged foot ensures that the foot can lie flat against the floor of a fuel tank in which the filter is arranged, and that as a result the filter sock will always be in contact with the floor over a significant area so that fuel can be drawn out of the tank, even when the fuel level in the tank is very low.

The stuffer arm may have a second hinge, between the connector and the end of the shank adjacent the connector.

This second hinge may also be associated with biasing means which cause the shank to be biased, about the second hinge axis, in a direction such that, in use, the foot will lie flat against the tank floor.

Alternatively, the shank may be joined to the connector through a fixed joint, with the shank being of a resilient material and being permanently directed in a direction which, in use, will be towards the tank floor.

The shank may be moulded of a plastics material, in which case the foot can be moulded integrally with the shank and connected thereto by a membrane hinge. Alternatively the shank can be of metal with the foot connected to the shank by a hinge. A still further possibility is to have a metal shank and a plastics foot which plugs onto the end of the shank and has an integral membrane hinge.

The shank may have a planar portion with lugs projecting from both sides of the planar portion to spread the sock on either side of the planar portion.

The foot preferably has a least three landing points extending below the planar portion, to make contact through the sock with the floor of a tank.

In one embodiment, the foot is H-shaped, with the hinge between the foot and the shank being between the cross-bar of the H-shape and the end of the shank.

The pump connector preferably includes two parts which can be sandwiched together with the filter sock between them, to seal the sock to the pump connector. The two parts preferably have mating collars which provide a through passage for fuel, with opposing flanges surrounding the collars. One flange has an upstanding, sharp-edged annular ridge surrounding and spaced from the collar on that part, and with an annular groove between the ridge and the collar. The other part then has a flat face opposing the ridge, so that when the parts are forced together, with the filter sock between them, ultrasonic welding of the joint ensures a complete seal between the two parts and the sock.

The mesh size of the filter sock is preferably such that, once it is wetted throughout by fuel, the interstices of the mesh remain filled with fuel, even though they may be above the level of the fuel in the tank, so that the pump can continue to suck fuel from the bottom of the tank, without sucking in air.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a fuel filter in accordance with the invention; Figure la is a perspective view of a filter sock for use in the fuel filter of the invention; Figure 2 is an exploded view of parts of a first embodiment of a filter in accordance with the invention; Figure 3 is a view, on a larger scale, of the connection end of the stuffer arm of the first embodiment; Figure 4 is a view, on a larger scale, of the foot end of the stuffer arm of the first embodiment; Figure 5 is an exploded view of parts of a second embodiment of a filter in accordance with the invention; Figure 6 is a view, on a larger scale, of the connection end of the stuffer arm of the second embodiment; and Figure 7 is a view, on a larger scale, of the foot end of the stuffer arm of the second embodiment.

Figure 1 shows, on a large scale, an in-tank fuel pump 10 located above the floor 12 of a fuel tank. Other walls of the fuel tank are not shown in this drawing. The pump 10 has a fuel inlet 14, and mounted on the bottom of this inlet 14 is a filter assembly generally indicated at 16.

The assembly comprises a pump connector 18, a filter sock 20 and a stuffer arm 22. As can be seen in Figure 1, the sock 20 is of a flexible mesh-like material in the form of a flat bag which is sealed to the connector at the joint between an upper part 24 and a lower part 26 of the connector. The sock 20 is held in an opened out position by the stuffer arm 22, and in particular by ligs or ribs on the arm. At the end of the stuffer arm 22 remote from the pump connector 18, there is a foot 28.

Figure 2 shows a stuffer arm 22 with a shank 30, an integrally moulded foot 28 and an integrally moulded pump connector lower part 26. The shank is of moulded plastics material with stiffening ribs 32, and is connected to the pump connector and to the foot by respective membrane hinges 34 and 36. The pre-set of the membrane hinges is such that the natural resting position of the shank 30 and of the foot 28 is approximately as shown by dotted lines 30a and 28a in Figure 1. The two hinges will have different spring rates, with the hinge 34 being stiffer than the hinge 36. When the filter and stuffer arm are assembled in a tank, they will take up the positions shown in bold lines in Figure 1, but if the tank floor 12 moves, the foot will be biased to follow the movement of the floor by the biasing energy stored in the hinges as a result of their having been caused to move away from their natural resting positions.

The foot 28 is of generally H-shape. The limbs of the Hshape are provided with projecting lugs 38 which extend form both sides and serve to spread open the filter sock 20. The lugs on the under face of the foot should lie flat on the tank floor (with the filter sock between the lugs and the floor).

Figures 5, 6 and 7 show an alternative embodiment. In this embodiment, the shank 130 of the stuffer arm 122 is a metal strip , with pressed-in stiffening ribs 132. The shank has tongues 133 and 135 which plug into corresponding sockets 137 and 139 on the connector 126 and the foot 128 respectively. The tongues 133, 135 have detents 141, and the sockets 137, 139 have latching fingers 143 which engage in the detents 141 to retain the three parts together.

In this embodiment, the hinges are formed by regions 134, 136 of the metal strip where a large part of the metal has been removed at 145 to confer flexibility and a hinge-like characteristic on that part of the strip. The remaining webs of metal which bound the opening 145 can be heat treated to give them the required flexibility.

The sock 20 will be generally of the configuration shown in Figure la. The only opening in the sock is a round hole 44, and the stuffer arm 22 is introduced into the sock through this opening, as is the bottom part 26 of the connector 18. A collar 46 of the connector part 26 extends out through this opening 44. Surrounding the collar 46 is a sharp-edged ridge 48, and an annular groove 50. An upper connector part 24 is fitted over the collar 46 (the upper part 24 has a collar 52 with internal diameter substantially equal to the external diameter of the collar 46). The two parts are an interference fit with one another and can be clamped together to squash the part of the sock 20 surrounding the hole 44 tightly between the rib 48 and the undersurface 54 of the upper part 24.An ultrasonic welding process then takes place to permanently bond these three components together in a leak-free manner. The groove 50 is provided to accommodate any excess mesh material of the sock 20 and the flash from the ultrasonic welding operation.

The upper component 24 also has a socket 56 for a filter support (not shown in the drawings). The filter support is a rod connected to the pump 10, and when the filter assembly is fitted to the fuel inlet 14, the supporting rod enters the socket, passes through a star washer S8 located between a pair of flanges on the upper component 24 and is therefore locked in place to hold the connector to the fuel inlet 14.

A joint reinforcement ring 64 also fits onto the fuel inlet 14, as a first step, to provide a fluid tight seal of the inlet 14 in the upper connector part 24.

The stresses produced in the arm will tend to force the foot 28 flat against the floor of the tank, even though the plane of the tank floor may not be at right angles to the axis of the fuel inlet 14.

Claims

1. An in-tank fuel filter having an annular pump connector for connecting the filter to a fuel line, a filter sock sealed to the pump connector so that, in use, the pump communicates with the inside of the filter sock, and a stuffer arm mounted at one end on the connector and extending therefrom inside the sock to spread the sock, the stuffer arm having a shank extending from the connector in a direction which, in use, will have a component extending towards the bottom of a fuel tank in which the filter is located, and a foot at the end of the stuffer arm end remote from the connector, which foot is connected to the shank by a hinge and is biased about the hinge axis in a direction such that, in use, the foot will lie flat against the tank floor.

2. A Fuel filter as claimed in Claim 1, wherein the hinge is a membrane hinge.

3. A fuel filter as claimed in Claim 1, wherein the hinge is a plastics membrane hinge.

4. A fuel filter as claimed in any preceding claim, wherein the stuffer arm has a second hinge, between the connector and the end of the shank adjacent the connector.

5. A fuel filter as claimed in Claim 4, wherein the second hinge is also associated with biasing means which cause the shank to be biased, about the second hinge axis, in a direction such that, in use, the foot will lie flat against the tank floor.

6. A fuel filter as claimed in any one of Claims 1 to 4, wherein the shank is joined to the connector through a fixed joint, with the shank being of a resilient material and being permanently directed in a direction which, in use, will be towards the tank floor.

7. A fuel filter as claimed in any preceding claim, wherein the shank is moulded of a plastics material and the foot is moulded integrally with the shank and connected thereto by a membrane hinge.

8. A fuel filter as claimed in any one of Claims 1 to 6, wherein the shank is of metal with the foot connected to the shank by a hinge.

9. A fuel filter as claimed in any one of Claims 1 to 6, wherein the shank is of metal and a plastics foot is plugged onto the end of the shank.

10. A fuel filter as claimed in any preceding claim, wherein the foot is H-shaped, with the hinge between the foot and the shank being between the cross-bar of the Hshape and the end of the shank.

11. An in-tank fuel filter as claimed in any preceding claim, wherein the pump connector includes two parts which can be sandwiched together with the filter sock between them, to seal the sock to the pump connector.

12. An in-tank fuel filter as claimed in Claim 11, wherein the two parts have mating collars which provide a through passage for fuel, with opposing flanges surrounding the collars.

13. An in-tank fuel filter as claimed in Claim 12, wherein one flange has an upstanding, sharp-edged annular ridge surrounding and spaced from the collar on that part, and with an annular groove between the ridge and the collar, and wherein the other part has a flat face opposing the ridge, so that when the parts are forced together, with the filter sock between them, ultrasonic welding of the joint ensures a complete seal between the two parts and the sock.

14. An in-tank fuel filter as claimed in any preceding claim, wherein the mesh size of the filter sock is such that, once it is wetted throughout by fuel, the interstices of the mesh remain filled with fuel, even though they may be above the level of the fuel in the tank, so that the pump can continue to suck fuel from the bottom of the tank, without sucking in air.

15. An in-tank fuel filter as claimed in substantially as herein described with reference to the accompanying drawings.