GB2356177A

GB2356177A - A motor vehicle fuel tank assembly

Info

Publication number: GB2356177A
Application number: GB9926607A
Authority: GB
Inventors: Raymond Paul Doherty
Original assignee: Bayerische Motoren Werke AG; MG Rover Group Ltd
Current assignee: Bayerische Motoren Werke AG; MG Rover Group Ltd
Priority date: 1999-11-11
Filing date: 1999-11-11
Publication date: 2001-05-16
Also published as: GB9926607D0

Abstract

A motor vehicle fuel tank assembly includes a tank 11 having a roof aperture 16 sealed by a flange 15 of a reserve module 14. A separate pump module 21 is mounted on the tank floor 13 and is connected to the reserve module by flexible pipes 26, 28 and 29. The pump module 21 includes an electrically driven pump which draws fuel through a pick-up strainer 23 and delivers it by means of a low pressure pump element 25 to a reserve container 17 in the reserve module. Fuel is then drawn from the reserve container through a high pressure pumping element 27 through an in-line fine filter 24 and delivered to a fuel feed outlet 19. A pressure regulator 18 controls the pressure of the delivery and spills excess fuel back into the reserve container 17.

Description

2356177 A Motor Vehicle Fuel Tank Assembly The invention relates to fuel

tank assemblies for motor vehicles. Typically, a fuel. tank assembly has to include an electrically driven fuel pump, a fuel pick-up strainer to protect the fuel pump from dirt or water which may have entered the tank, a fuel filter to filter the fuel delivered by the pump, a pressure relief valve or regulator to limit the pressure of the fuel delivered by the pump, a reserve fuel container or pot to supply fuel to the pump when the main level in the tank becomes low and a replenishment system for the reserve container. The assembly usually also includes a fuel level sensor to act as a sender unit for a fuel level gauge It has become a major design problem to package the above mentioned devices within the fuel tank, particularly to ensure that the fuel pick-up is in the ideal position, at or near to the centre of the tank, and also to ensure that the reserve container is of a capacity which gives acceptable gradient and cornering performance, particularly with vehicles with off road capability and large engines.

This design problem is exacerbated by vapour emission legislation which, in practical terms, limits the number and size of fuel tank openings to one of a relatively small diameter. Furthermore, there is a limited packaging space for the fuel tank within the vehicle itself and typically the fuel tank overall height is lower than 200mm. This makes it very difficult to install all the necessary devices mentioned above within a single module, particularly the provision of a reserve container of sufficient capacity.

The present invention aims to alleviate the above mentioned problems.

According to the invention there is provided a motor vehicle fuel tank assembly comprising a tank for containing liquid fuel, the tank including a roof, a floor and an aperture in or adjacent the roof, a flange arranged to seal the aperture, a reserve fuel container mounted within the tank and a fuel pump module including an electrically driven fuel pump arranged to deliver fuel from the reserve container to a fuel feed outlet and means to draw fuel from the vicinity of the floor and deliver it to the reserve container, wherein the fuel pump module is 5 mounted within the tank separately from the reserve module.

The arrangement allows for a maximised capacity for the reserve container. It also enables the height of the pump module to be kept to a minimum which allows for maximum distortion of the tank in the event of collision damage without risk of the pump module puncturing the tank.

Conveniently, the reserve container is mounted from the flange. However, the reserve container may be mounted from the roof or the floor of the tank if required.

Preferably, the reserve fuel container is moulded from a resilient plastics material such as a polyolefin, in which case the reserve fuel container may be made by blow moulding. This allows for a container which will distort with the 15 fuel tank in the event of collision damage.

Preferably, the reserve fuel container is cylindrical. This allows the maximum capacity of fuel where the reserve container is assembled by insertion through a circular aperture. The reserve fuel container may be of a bent tubular configuration, e.g. L-shaped in elevation or plan to further maximise the fuel 20 capacity where tank height is limited.

Preferably, the pump module includes a fuel pick-up strainer for fuel drawn from the vicinity of the floor, in which case the strainer may include an upper strainer wall and a lower strainer wall joined at their peripheries to define a strainer chamber.

Conveniently the pump module includes an in line filter for the fuel delivered by the fuel pump to the feed outlet.

A pressure relief valve may be mounted on the flange and arranged to deliver excess fuel into the reserve container.

In one arrangement, the fuel pump includes a pump element operative to pump fuel from the vicinity of the tank floor to the reserve container.

In another arrangement, the pump module includes a discriminator valve in a fuel flow path between the reserve container and an inlet of the fuel pump, the discriminator valve being normally closed but being open when there is a scarcity of fuel in the vicinity of the tank floor. Where the pump module includes a fuel pick-up strainer which defines a strainer chamber as referred to above, a collector pot may extend upwardly from the periphery of the strainer to collect fuel discharged from the reserve container through the discriminator valve.

Conveniently, the discriminator valve comprises a flexible diaphragm mounted in a housing having on one side of the diaphragm, a valve seat formed at the end of a connection to the reserve container and a discharge orifice and on the other side of the diaphragm a connection to the inlet of the pump, a valve member on the diaphragm to control flow from the reserve container past the valve seat and spring means to bias the valve member towards the valve seat, the arrangement being such that an increased pressure drop across the pick-up strainer cau sed by an shortage of liquid fuel acts on the diaphragm to pull the valve member away from the valve seat again st the bias of the spring to allow fuel to flow from the reserve container and into the collector pot by way of the discharge orifice The invention will now be described by way of example and with reference to the accompanying drawings, of which:

Fig.1 is a diagrammatic cross-sectional view of a first embodiment of a motor vehicle fuel tank assembly according to the invention; Fig.2 is an enlarged view based on Fig. 1 showing parts in more detail; Fig.3 is a view similar to Fig.2 showing a second embodiment of the invention.

Fig. 4 is a view similar to Fig. 2 showing a second embodiment of the invention; and Fig.5 is a view similar to Fig.1 showing a modification to the second embodiment.

Referring to Figs.1 and 2, a motor vehicle fuel tank assembly includes a fuel tank 11 for containing liquid fuel such as petrol (gasoline) or diesel. The tank includes a roof 12, a floor 13 and an aperture 16 in the roof.

A reserve module 14 includes a generally circular flange 15 which is arranged to seal the aperture 16 and a generally cylindrical reserve fuel container 17 mounted on and below the flange 15. The reserve module 14 also includes a pressure relief valve.18 mounted on the flange 15 and a feed outlet 19 for connection to an engine of the vehicle. The reserve fuel container 17 is conveniently blow-moulded from a resilient plastics material such as a polyolefin.

Low or high density polyethylenes are suitable, as is polypropylene.

A fuel pump module 21 is mounted within the tank 11 separately from the reserve module 14 and includes an electrically driven fuel pump 22, a fuel pick-up strainer 23 and an in-line fine filter 24. The pick-up strainer 23 is positioned close to the tank floor 13 and is positioned centrally so that when the fuel level in the tank 11 is tilted (by the vehicle being on a gradient or subject to cornering forces) there is no particular tilt direction which is more prone to leave the pick-up strainer 23 above the fuel level.

The fuel pump 22 has two pump elements. A first or low pressure pump element 25 has an inlet connected to the pick-up strainer 23 and an outlet connected by a flexible pipe 26 to the reserve container 17. A second or high pressure element 27 has an inlet connected to the reserve container 17 by another flexible pipe 28 and an outlet connected to the in-line, filter 24.. A third flexible pipe 29 connects the in-line filter 24 to the pressure relief valve 18. An electrical connector terminal block 31 is moulded as part of the flange 15 to provide electrical connections to the electric fuel pump through a flexible cable 32 and for a fuel level sender (not shown) which may be part of the reserve module 14 or the pump module 21.

In use the electric fuel pump 22 operates continuously during starting and running of the engine. Fuel is drawn from the vicinity of the tank floor 13 through the pick-up strainer 23 the low pressure pumping element 25, flexible pipe 26 and into the reserve container 17. Excess fuel is allowed to spin from an orifice 33 near the top of the reserve container 17 and back into the main volume of the tank 11.

The high pressure pumping element.27 draws fuel from the reserve container 17 through pipe 28 and delivers it through the electric motor itself into the in-line filter 24 and through flexible pipe 29 to the relief valve 18. Fuel spills from the pressure relief valve 18 into the reserve container 17 when pressure delivered by the high pressure pumping element 27 reaches a pre-set magnitude.

The electric fuel pump 22 may be conveniently arranged co-axially within the irL-hne filter 24 and this filter may have an outer casing which forms the main housing of the pump module 21.

In order to assemble the fuel tank assembly shown in Figs. 1 and 2, the pump module 21 and the reserve module 14 are assembled as separate components and linked by the hoses 26, 28 and 29 the flexible cable 32. The pump module 21 is then inserted through the open aperture 16 and secured in place on the tank floor 13. This may be achieved by a bayonet fitting (e.g. as shown in DE-A-39 20 276) or the tank floor 13 may have a shallow cylindrical recess 34 as shown in Figs. 1 and 2 and be retained by clips. Another possibility is for the pump module 21 to be spring loaded between the tank floor 13 and the tank roof 12.

Following insertion of the pump module 21 the reserve container 17 is lowered through the aperture 16 and the flange 15 secured in place to seal the aperture. The reserve container 17 may be rigidly connected to the flange 17 or may be connected to it by resilient or telescopic mountings which allow it to rest on the floor 13.

In the second embodiment shown in Fig.3 parts which are the same as or similar to those shown in Figs.1 and 2 have the same reference numeral but with the addition of 100. The arrangement is generally similar to that shown in Fig.2 except that the fuel pump 122 has a single pumping element which draws fuel from a chamber within the pick-up strainer 123. When there is an adequate level of fuel inside the tank 111 fuel is drawn through the pick-up strainer 123 into the chamber and through the fuel pump 122 as before. However, if this level drops below the top of the pick-up strainer 123 a discriminator valve 135 opens to allow fuel to flow through flexible pipe 128 from the reserve container 117. The pressure relief valve 118 operates to keep the reserve container 117 fined in the normal way. The discriminator valve 135 operates by virtue of an increased pressure drop 25. across the pick-up strainer 123 when this is no longer totally immersed in liquid fuel. One such arrangement is described in US 4,747, 388. Other arrangements are shown in US 4,672,937 and US 4,974,570.

7, In the third embodiment shown in Fig.4 parts which are the same as or imilar to those shown in Fig.3 have the same reference numeral but with the further addition of 100. The arrangement is generally similar to that shown in Fig.3 except that there is no reserve module as such, the reserve fuel container 217 5. being mounted (e.g. by a bayonet connection) on the tank roof 212 and connected to the pressure regulator by a flexible pipe 239. The discriminator valve 235 is also shown in more detail.

The discriminator valve 235 comprises a flexible diaphragm 241 mounted in a housing 242 having on one side of the diaphragm a valve seat 243 formed at the end of a connection to the flexible pipe 228 connecting the discriminating valve to the reserve container 217. On the other side of the diaphragm there is a pipe connection 244 to the inlet of the pump 222. A generally cylindrical wall extends from the outer periphery of the strainer 223 to form a collector pot 245. A valve member 246 on the diaphragm 241 controls flow from the reserve container 217 past the valve seat 243 and through a discharge orifice 247 in the discriminator valve housing 242 on the same side of the diaphragm 241 as the valve seat 243. A spring 248 biases the valve member towards the valve seat 243.

The fuel pump 222 draws fuel from chamber 251 within the pick-up strainer 223. When there is an adequate level of fuel inside the tank 211 fuel is drawn through the pick-up strainer 223 into the chamber 251 and through the fuel pump 222 as before. However, if this level drops such that the pick-up strainer 123 is no longer totally immersed in liquid fuel there is an increased pressure drop across the pick-up strainer which acts on the diaphragm 241 to pull the valve member 246 away from the valve seat 243 against the bias of the spring 248. This allows 25. fuel to flow through the flexible pipe 228 from the reserve container 217 and into the collector pot 245 by way of the discharge orifice 247. The pressure relief valve 218 operates to keep the reserve container 217 filled in the normal way.

In the modification shown in Fig.5, the reserve fuel container 217A is Lshaped in elevation whilst remaining generally circular in cross-section; i.e. it is generally shaped like a filled stocking or sock. This allows the reserve container 217A to have an increased capacity whilst still being capable of being inserted through a roof aperture 216 of normal size. Other complex configurations may be used to maximise the capacity of the reserve fuel container, e.g. the container may also be L-shaped in plan view.

VVhilst the aperture 16, 116, 216 is in the roof of the tank in all the embodiments described so far, it may be elsewhere on the tank wall, e.g. in a side of the tank adjacent to the roof, if installation or maintenance requirements so dictate.

The arrangements described are an improvement over the conventional arrangement of a single tank module in which the pump and in-line filter are inside the reserve container. The diameter of the reserve container is restricted by the diameter of the tank roof aperture e.g. typically 110mm and its height is limited by the space available for the tank in the motor vehicle. Putting the electric pump, the pick-up strainer and the in-line filter into a separate module frees-up valuable space in the reserve container. It also gives a greater freedom of choice for the position of the mounting aperture in the tank roof so that when mounted in a vehicle it can be accessible for maintenance or repair. Furthermore, the pump module can be shorter in height than a normal tank module and this gives more room for deflection of the tank in the event of collision distortion of the vehicle, thereby avoiding the possibility of sharp or rigid parts of the module penetrating the tank wall and causing fuel leakage. Conversely, the height (and 25. hence the capacity) of re serve container can be maximised since this can be of a relatively flexible material which will easily distort with the tank without significant risk of puncturing the tank itself.

Claims

-9CLAIMS

1. A motor vehicle fuel tank assembly comprising a tank for containing liquid fuel, the tank including a roof, a floor and an aperture in or adjacent the roof, a flange arranged to seal the aperture, a reserve fuel container mounted within the tank and a fuel pump module including an electrically driven fuel pump arranged to deliver fuel from the reserve container to a fuel feed outlet and means to draw fuel from the vicinity of the floor and deliver it to the reserve container, wherein the fuel pump module is mounted within the tank separately from the reserve module.

2. An assembly according to claim 1 wherein the reserve container is mounted from the flange.

3. An assembly according to claim 1 wherein the reserve container is mounted from the roof of the tank.

4. An assembly according to any preceding claim wherein the reserve fuel container is moulded from a resilient plastics material.

5. An assembly according to claim 4 wherein the resilient plastics material is a polyolefin.

6. An assembly according to claim 4 or claim 5 wherein the reserve fuel container is blow moulded.

7. An assembly according to any preceding claim wherein the reserve fuel container is cylindrical.

8. An assembly according to any preceding claim wherein the reserve fuel container is of a bent tubular configuration, e.g. L-shaped in elevation or plan.

9. An assembly according to claim 8 wherein the reserve fuel container is Lshaped in elevation.

10. An assembly according to claim 8 or claim 9 wherein the reserve fuel container is L-shaped in plan.

11. An assembly according to any preceding claim wherein the pump module includes a fuel pick-up strainer for fuel drawn from the vicinity of the floor.

12. Am assembly according to claim 11 wherein the strainer includes an upper strainer wall and a lower strainer wall joined at their peripheries to define a strainer chamber.

13. An assembly according to any preceding claim wherein the pump module includes an in-line filter for the fuel delivered by the fuel pump to the feed outlet.

14. An assembly according to any preceding claim wherein a pressure relief valve is mounted on the flange and is arranged to deliver excess fuel into the reserve container.

15. An assembly according to any preceding claim wherein the fuel pump includes a pump element operative to pump fuel from the vicinity of the tank floor to the reserve container.

16. An assembly according to any of claims 1 to 14 wherein the pump module includes a discriminator valve in a fuel flow path between the reserve container and an inlet of the fuel pump, the discriminator valve being normally closed but being open when there is a scarcity of fuel in the vicinity of the tank floor.

17. An assembly according to claim 16 when dependent from claim 12 wherein a collector pot extends upwardly from the periphery of the strainer to collect fuel discharged from the reserve container through the discriminator valve.

18. An assembly according to claim 18 wherein the discriminator valve comprises a flexible diaphragm mounted in a housing having on one side of the diaphragm, a valve seat formed at the end of a connection to the reserve container and a discharge orifice and on the other side of the diaphragm a connection to the inlet of the pump, a valve member on the diaphragm to control flow from the reserve container past the valve seat and spring means to bias the valve member towards the valve seat, the arrangement being such that an increased pressure drop across the pick-up strainer caused by an shortage of liquid fuel acts on the diaphragm to pull the valve member away from the valve seat against the bias of the spring to allow fuel to flow from the reserve container and into the collector pot by way of the discharge orifice

19. A motor vehicle fuel tank assembly substantially as described herein with reference to Fig.1 and Fig.2, Fig.3, Fig.4 or Fig.4 as modified by reference to Fig. 5 of the accompanying drawings.