GB2288374A

GB2288374A - Liquid gas fuel system for a motor vehicle

Info

Publication number: GB2288374A
Application number: GB9407389A
Authority: GB
Inventors: David Roland Lampitt
Original assignee: GUIDE FRIDAY Ltd
Current assignee: GUIDE FRIDAY Ltd
Priority date: 1994-04-14
Filing date: 1994-04-14
Publication date: 1995-10-18
Anticipated expiration: 2014-04-14
Also published as: GB2288374B; GB9407389D0

Abstract

A plurality of fuel tanks (1, 2, 3, 4) each having a flow control valve (7) arranged to permit flow of fuel therethrough up to a certain flow rate, are connected by fuel pipes (8 - 11) to a receiver (12). The receiver (12) includes a plurality of non-return inlet valves (22, 23, 24, 25) and an outlet defined by fuel pipe (13) through which fuel can pass to the engine (6) of the vehicle. Thus, if a fracture occurs at point (36) in line (11), flow from tank (4) will be prevented by the valve (7) in tank (4) and flow from the other tanks will be prevented from reaching the fracture by the non-return valve (25). A flow control valve (35) may be provided in the receiver (12) to prevent escape of fuel in the event of a fracture in line (13). <IMAGE>

Description

A LIQUID GAS FUEL SYSTEM FOR A MOTOR VEHICLE The invention relates to a liquid gas fuel system for a motor vehicle and is particularly, but not exclusively, concerned with a liquid gas fuel system for motor vehicles such as buses which utilise a plurality of fuel storage tanks. Such a fuel is typically LPG such as liquid propane.

Hitherto, it has been proposed to link together through T-connectors fuel pipes from liquid gas storage tanks to provide a single final pipe along which fuel can flow towards an engine. If there is a fracture in the fuel pipe from one of the tanks with such an arrangement, a flow control valve at the outlet of the tank will close to prevent further flow of fuel from that particular tank. Also, an excess flow valve in the second tank joined to the first tank through a T-connector will prevent flow of fuel from the second tank out of the fracture. However, if a fracture were to occur in a pipe extending from the T-connector towards the engine, the excess flow valves in the fuel tanks would fail to operate if the flow rate through the fuel pipe downstream of the T-connector were insufficient to permit fuel to flow from each of the tanks fast enough to operate the flow control valves at the tanks.

In certain circumstances, it is required to use three or more fuel tanks which are interconnected to provide, eventually, a single pipe through which fuel flows towards the engine. Where four tanks are provided, they are usually connected in pairs through respective Tconnectors to provide two outlets from the T's which are subsequently connected through a further T-connector to provide, eventually, the single outlet for a pipe through which fuel can flow towards the engine. If a fracture occurs in the line between the T-connector connecting one pair of tanks and the down stream T-connector, the flow control valves in that pair of tanks may not operate as the flow through the interconnecting T-connector may not be sufficient to operate the flow valves. Moreover, in such a case, fuel from the other pair of tanks may also leak through the fracture.

An object of the present invention is to provide an improved liquid gas fuel system for a motor vehicle which is intended to reduce substantially the above problem.

According to a first aspect of the invention there is provided a liquid gas fuel system for a motor vehicle comprising a plurality of fuel storage tanks, respective fuel flow paths from the tanks, flow control means in the flow paths arranged to permit flow of fuel therethrough up to a certain flow rate and a receiver including a plurality of non-return inlet valves connected to the respective fuel flow paths and which permit fuel to enter the receiver and an outlet through which fuel can pass from the receiver towards an engine of the vehicle.

With such an arrangement, a fracture in a said fuel flow path will cause the flow control means to operate and thereby prevent further flow of fuel from the associated fuel storage tank. Moreover, the non-return inlet valve associated with that flow path will prevent fuel in the receiver from the remaining fuel storage tanks reaching the fracture.

In prior art systems, if a fracture occurs in the pipe from the final T-connector which leads to the engine, the flow through the fracture will invariably be insufficient to permit closure of the flow control valves associated with the fuel tanks. In order to reduce that particular problem, a further flow control means may be provided at the outlet of the receiver. In that way, if there is a fracture in the fuel flow path downstream of the receiver the further flow control means will operate to stem the flow of fuel from the receiver.

The receiver may comprise a hollow body having a closure wall at one side in which one or more of the non-return valves is mounted. The hollow body may also have another side wall in which the further flow control means is mounted. Preferably, the aforesaid side walls lie on opposite sides of the hollow body.

The further flow control means of the receiver may comprise a valve which is normally held clear of a seat to permit flow to pass between the valve and the seat up to a certain flow rate, the valve being arranged to close and interrupt flow when the given flow rate is exceeded.

The flow control valves of the fuel storage tanks can be similarly constructed.

According to a second aspect of the invention there is provided a receiver for use in a liquid gas fuel system for a motor vehicle, the liquid fuel being stored in a plurality of fuel storage tanks having respective flow control means therein arranged to permit fuel flow therethrough up to a certain flow rate, the receiver including plurality of non-return inlet valves arranged to be connected to respective fuel flow paths from the fuel storage tanks and which permit fuel to enter the receiver, and an outlet through which fuel can pass from the receiver towards the engine.

The receiver may include the features of any of the consistory clauses relating to the first aspect of the invention.

A liquid gas fuel system in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1 is a diagrammatic view of a system in accordance with the invention Fig 2 is an end view of a receiver of the system of Fig 1 looking in the direction of arrow II in Fig 1 and Fig 3 is an exploded cross-section of the receiver shown in Fig 2 on the line III III in Fig 2 In Fig 1, four fuel tanks 1, 2, 3 and 4 are provided with respective solenoid operated outlet valves 5 which will be closed when an ignition circuit for an engine 6 is switched off and which will open to allow fuel to flow from the fuel tanks when the ignition circuit is switched on. The solenoid valves 5 are associated with flow control valves 7 of known kind which will allow fuel to flow therethrough provided that the fuel flow does not exceed a given rate. Such flow control valves are known in the art as excess flow valves are available from HKL Gaspower Ltd of Birmingham.

An outlet from each flow control valve 7 is connected by means of fuel pipes 8, 9, 10 and 11 to a receiver 12.

The receiver 12 will be described in detail below. Fuel leaves the receiver 12 through a fuel pipe 13 and enters a vaporising unit 14 of known kind through which cooling water from the engine 6 passes to provide a source of heat to assist vaporisation of the fuel. Fuel vapour enters a carburettor 15 of known kind and enters the engine 6 as a metered air/fuel mixture. A vacuum shutoff valve 21 is provided immediately upstream of the vaporising unit 14. The vacuum shut-off valve 21 is connected to an inlet manifold of the engine 6 and senses engine depression. On sensing vacuum, the valve 21 opens and permits fuel to flow to the vaporising unit 14. The vaporising unit 14, carburettor 15 and vacuum shut-off valve 21 are well known on existing LPG fuel systems for vehicles.

The receiver 12 is now described in detail and comprises in the present example a rectangular housing 17 having a cylindrical bore 18 therein. The housing 17 has a integral end wall 19 and a detachable end wall 20. The end wall 20 supports four non-return inlet valves 22, 23, 24 and 25. The non-return valves are of known kind and are available from HKL Gaspower Ltd of Birmingham. The end wall 20 has a cylindrical extension 26 of complementary diameter to the bore 18 and carries an Oring 27 in a peripheral groove 28. In use, the end wall 20 is assembled on to the housing 17 with the cylindrical extension 26 locating within the bore 18 and the O-ring 27 sealing against the wall of the bore. Securing bolts 29 are used to screw the wall 20 to the housing 17, the bolts 29 locating in screw-threaded holes 30 in the housing. The fuel pipes 8, 9, 10 and 11 are suitably connected to connector ends 32 of the non-return valves 22, 23, 24 and 25.

The end wall 19 of the housing 17 defines an outlet 33 which carries a pipe connector 34 connected to the fuel pipe 13. The outlet 33 also includes a flow control valve 35 which is similar to the flow control valves 7. The flow rate at which the flow control valves 7 and 35 will close is approximately 3 gallons per minute. The flow control valve 35 permits fuel to flow from the hollow interior of the housing 17 through the outlet 33 and along the fuel pipe 13 towards the vaporising unit 14.

The flow-control valve 35 comprises a valve member (not shown) which is normally held clear of a seat by means of a suitable spring so that fuel can flow between the valve member and the seat through the outlet 33. However, in the event of sufficient rise in flow rate, the moving fuel urges the valve member on to its seat to prevent further fuel flow through the valve and the valve member is maintained in that position by fuel pressure. The flow control valves 7 can be similarly constructed.

In use, and with the vehicle ignition circuit switched on, LPG fuel in liquid form stored under pressure in the fuel tanks 1, 2, 3 and 4 will flow through fuel pipes 8, 9, 10 and 11 and through the respective non-return valves 22, 23, 24 and 25 so as to enter the bore 18 of the receiver. From the interior of the receiver, the fuel will flow through the flow control valve 35, through the outlet 33 and along the fuel pipe 13 towards the vaporising unit 14.

Should a fracture occur, say, at point 36 in line 11, there will be instantaneous tendency for fuel in the tank 4 to rush through the flow control valve 7 and escape from the fracture 36. However, the increased rate of fuel flow will cause the valve 7 to close virtually instantaneously to prevent the fuel escaping from the fracture 36. Moreover, fuel from the remaining fuel tanks 1, 2 and 3 flowing into the receiver 17 through the non-return valves 22, 23 and 24 will be prevented from flowing to the fracture 36 by operation of the non-return valve 25. In effect, there will be virtually zero leakage of fuel from the fracture 36 which is most advantageous. There will be a similar effect if fractures occur in any of the other fuel pipes 8, 9 and 10.

Should a fracture occur in the fuel pipe 13, for example at point 37, there will be a tendency for fuel to rush from the interior of the receiver 17 and escape from the fracture 37. However, the increased rate of fuel flow will cause the flow control valve 35 to close virtually instantaneously so as to prevent flow of fuel from the receiver, thereby preventing the fuel escaping from the fracture 37.

It will be appreciated that the system will prevent unwanted escape of fuel from the fuel tanks 1, 2, 3 and 4 in those areas that are most prone to fracture in a liquid gas fuel system for a motor vehicle.

Claims

1. A liquid gas fuel system for a motor vehicle comprising a plurality of fuel storage tanks, respective fuel flow paths from the tanks, flow control means in the flow paths arranged to permit flow of fuel therethrough up to a certain flow rate and a receiver including a plurality of non-return inlet valves connected to the respective fuel flow paths and which permit fuel to enter the receiver and an outlet through which fuel can pass from the receiver towards an engine of the vehicle.

2. A liquid gas fuel system according to claim l in which the receiver comprises a hollow body having a closure wall at one side in which one or more of the non-return valves is mounted.

3. A liquid gas fuel system according to claim 1 or 2 in which further flow control means is provided at the outlet of the receiver.

4. A liquid gas fuel system according to claim 3 in which the hollow body also has another side wall in which the further flow control means is mounted.

5. A liquid gas fuel system according to claim 4 in which the aforesaid side walls lie on opposite sides of the hollow body.

6. A liquid gas fuel system according to claim 3, 4 or 5 in which the further flow control means of the receiver comprises a valve which is normally held clear of a seat to permit flow to pass between the valve and the seat up to a certain flow.rate, the valve being arranged to close and interrupt flow when the given flow rate is exceeded.

7. A liquid gas fuel system according to any preceding claim in which the flow control means of the fuel storage tanks each comprise a valve which is normally held clear of a seat to permit flow to pass between the valve and the seat up to a certain flow rate, the valve being arranged to close and interrupt flow when the given flow rate is exceeded.

8. A receiver for use in a liquid gas fuel system for a motor vehicle, the liquid fuel being stored in a plurality of fuel storage tanks having respective flow control means therein arranged to permit fuel flow therethrough up to a certain flow rate, the receiver including a plurality of non-return inlet valves arranged to be connected to respective fuel flow paths from the fuel storage tanks and which permit fuel to enter the receiver, and an outlet through which fuel can pass from the receiver towards the engine.

9. A receiver according to claim 8 in which the receiver comprises a hollow body having a closure wall at one side in which one or more of the non-return valves is mounted.

10. A receiver according to claim 8 or 9 in which further flow control means is provided at the outlet of the receiver.

11. A receiver according to claim 10 in which the hollow body also has another side wall in which the further flow control means is mounted.

12. A receiver according to claim 11 in which the aforesaid side walls lie on opposite sides of the hollow body.

13. A receiver according to claim 10, 11 or 12 in which the further flow control means of the receiver comprises a valve which is normally held clear of a seat to permit flow to pass between the valve and the seat up to a certain flow rate, the valve being arranged to close and interrupt flow when the given flow rate is exceeded.

14. A receiver according to any of claims 8 to 13 in which the flow control means of the fuel storage tanks each comprise a valve which is normally held clear of a seat to permit flow to pass between the valve and the seat up to a certain flow rate, the valve being arranged to close and interrupt flow when the given flow rate is exceeded.

15. A liquid gas fuel system constructed and arranged substantially as described herein with reference to the accompanying drawings.

16. A receiver constructed and arranged substantially as described herein with reference to the accompanying drawings.