GB2165306A - Automotive engine multiple fuel tank system - Google Patents

Abstract

A shuttle valve 54 is operated by a diaphragm 82 in response to the outlet pressure of the operative one of two electric pumps which is manually switched on to supply fuel from a respective fuel tank. The operative pump is connected to a diesel engine fuel supply device and the device is also connected to the tank in use for return of excess fuel. An overcentre spring 90 provides snap action of the valve 54 between its end positions in response to reversal of pressure conditions in the diaphragm chambers 78 and 80. <IMAGE>

Description

SPECIFICATION Automotive engine multiple fuel tank system This invention relates in general to an automotive type fuel system, and more particularly, to one for a truck in which fuel is supplied to the engine selectively from a plurality of fuel tanks, excess fuel from the engine being returned always to the particular tank from which it originated.

A primary purpose of this invention is to provide a fuel tank switching system that permits the selective supply of fuel from any one of a plurality of fuel tanks while assuring the return of excess fuel from the engine to that particular tank.

Automotive vehicles such as trucks frequently have dual fuel tanks, one of which may be located midship of the vehicle, the other at the rear or other location. Depending upon the location and size of the load, the vehicle operator may wish to be selective in drawing fuel from one tank or the other as a means of compensating for the unbalance of this load. For example, if the vehicle is heavily loaded to the rear, the operator may want to burn off fuel from the rear tank while maintaining the midship tank full. Alternatively, the operator may wish initially to draw a small amount of fuel from one tank and then switch to the other for a longer period of time.

When a fuel injection type engine is used, fuel generally is supplied to the injectors in a volume in excess of that required to assure an adequate supply at all times. This necessitates a flow of return fuel to the fuel tank. In the case of dual fuel tanks with selective operation as described above, it is necessary to assure that the fuel will always be returned to the same tank from which it was supplied.

Otherwise, an overfill or other condition might occur. Also, if fuel is being burned from one tank to redistribute the load, it is desirable to return the excess fuel to that same tank to control the load distribution.

According to the present invention there is provided a manually controllable fuel tank switching system as herein set forth in Claim 1.

The invention will now be described further, by way of example, with reference to the accompany drawing in which the single figure schematically illustrates one embodiment of the invention.

Fuel tank switching devices are known.

However, in most instances, these devices do not permit the selective switching from one tank to the other, and generally automatically switch from one tank only when the other tank is nearly empty. Furthermore, these known switching devices generally do not provide for a return of fuel to the same tank from which it was originally supplied. In brief, the known tank switching devices do not include a fuel pressure sensitive shuttle valve that is movable at will in response to the selective supply of fuel from one of a plurality of fuel tanks For example, US 3,550,613, Barber, shows a device for switching the fuel supply from one tank to another to maintain a supply of fuel to an engine carburetor at all times.

There is no return line since no excess fuel is supplied to the carburetor, and the purpose of the switching device is only to maintain a constant supply of fuel.

US 2,634,743, Audemar, shows a shuttle valve mechanism permitting flow of fuel from one supply source to a utilization device while blocking flow from the opposite tank. Again, no return line for excess fuel is provided.

US 3,592,215, Davis, shows a fluid switching device that includes an overcenter spring mechanism to provide a snap action to the valving.

US 1,858,291, Burdett, US 2,354,286, Whaley, Jr., US 3,001,541, and US 3,033,220, St. Clair, US 1,925,610, Shinn, US 3,148,364, Engels, et al, and FR 1,310,675, all show some form of fluid switching device for providing a changeover of fluid from one supply to the other.

None of the above prior art, however, shows a fuel tank switching device that is manually selective to at will switch the supply from one tank to another and back again, with lines to return excess fuel to the particular tank from which it was supplied, the switching device including a shuttle valve operable by a fuel pressure differential sensitive servo means combined with an overcenter type spring to provide an automatic snap action switching of the fuel supply from one tank to another upon initiation by the operator.

Referring now to the drawing, the figure illustrates schematically a fuel tank switching system that includes first and second sources of fuel 10 and 12, each of which is adapted to be connected, as indicated, to a separate fuel tank filled with fuel. Although not shown, each of the tanks would contain a known type of electric fuel pump that is operable at will to pump or not pump fuel under pressure from a particular tank into lines 10 or 12, depending upon which fuel pump is rendered operable by the operator.

The fuel in source lines 10 and 12 are connected by respective fuel supply lines 14 and 16 through a shuttle valve or switching mechanism 18 and connecting lines 20 and 22 to a common fuel distribution or supply line 24. The latter is adapted to be connected to a fuel utilization device, which may be a carburetor or throttle body for a truck type diesel engine or the like, for example. The diesel engine would be provided with a number of fuel injectors that generally require a supply of fuel that is in excess of its flow requirments in order to maintain a constant supply of fuel to the injectors at all times.

The system is provided with a fuel flow return line 28 from the utilization device that is connected through the shuttle valve mechanism 18 to individual fuel flow return lines 30 and 32 connected respectively to the first and second tanks, as indicated.

The shuttle valve mechanism 18 consists of a hollow housing 34 divided into two end compartments 36 and 38 and a central compartment 40 by two partitions 42 and 44.

The end compartments 36 and 38 are further subdivided by partitions 46 and 48, having central openings 50, 52 constituting valve seats for cooperation with a shuttle valve 54 to be described. The central compartment 40 also is subdivided by a pair of partitions 56 and 58 also having central apertures serving as valve seats 60, 62 for cooperation with the shuttle valve 54.

The shuttle valve 54 consists of a pair of conically shaped end lands 64 and 66 joined to a similarly shaped central land 68 by a pair of neck portions 70, 72 of reduced diameter.

The valve 54 is adapted to be reciprocated in opposite directions to alternately seat the conical land portions against one or the other of the valve seats to control the flow of fuel selectively from one tank or the other to the utilization device and return of excess fuel to the particular tank from which it was supplied, as will be described.

The upper end chamber 36 interconnects the supply line 14 from the first tank and line 20 leading to the utilization device. The lower end chamber 38 likewise connects the supply line 16 from the second tank to the connecting line 22 leading to the utilization device.

The central chamber 40 alternately connects excess fuel in the common return line 28 through the shuttle valve mechanism to a return branch passage or line 30 leading to the first tank or alternately to return branch passage or line 32 leading to the second tank.

As stated previously, the shuttle valve mechanism is adapted to be moved with a snap action by the fuel pressure differential between the supply tanks. More particularly, a fuel pressure sensitive servo mechanism 74 includes a hollow housing 76 partitioned into two fuel chambers 78 and 80 by a flexible annular diaphragm 82. Chamber 78 is adapted to be connected to the fuel in the first tank by a line 84 connected to supply line 14. Fuel chamber 80 is adapted to be connected to the fuel from the second tank through a connecting line 86 intersecting the fuel supply line 16.

The diaphragm 82 is secured to a rod-like member 88 connected by an overcenter spring 90 to a lever 92. The latter is pivotally mounted at one end 94 and universally connected at its opposite end 96 to a rod-like extension 98 of the shuttle valve 54.

The operation is believed to be clear from the above and a consideration of the drawing.

However, in brief, assume that the engine with which this switching system is to be associated is operative. Assume the driver has selectively activated, for example, the electric fuel pump in the first tank to supply fuel under pressure into lines 10 and 14. The fuel under pressure in branch line 84 therefore fills chamber 78 and causes diaphragm 82 to be in the position shown in the figure, the fuel in chamber 80 not being under pressure. This downward position has caused the overcenter spring 90 to move the lever 92 to the position shown to locate the shuttle valve 54 as shown, permitting fuel flow from the first tank through line 14 and end chamber 36 to connecting line 20 leading to the utilization device. At the same time, excess fuel from the device can flow through common return line 28 to line 30 leading directly to the first tank.

The return line 32 to the second tank is blocked by the central land 68, and any flow from the second tank is blocked by the end land 66.

Assume that the operator desires to bleed off some of the fuel from the second tank, or desires to activate fuel flow from the second tank for any reason. The electric fuel pump in the second tank therefore will be switched on and the fuel pump in the first tank shut off.

Fuel flow at this time from the second tank entering line 86 will fill fuel chamber 80 with fuel under pressure and move diaphragm 82 upwardly from the position shown against the fuel in chamber 78, which at this time is not under pressure. The upward movement of the diaphragm causes the overcenter spring 90 to arcuately swing the actuating lever 92 with a snap action overcenter to move the shuttle valve 54 upwardly from the position shown in the figure. This will automatically connect the fuel from the second tank in line 66 to connecting line 22 and to the utilization device while at the same time blocking fuel flow in supply line 14 to connecting line 20 due to land 64 seating in seat 50. The central land 68 also moves to block return flow into line 30 leading to the first tank while opening the flow into return line 32 leading directly to the second tank.

From the foregoing, it will be seen that the invention provides a fuel tank switching system that permits the selective flow of fuel from any one of a plurality of fuel tanks to a fuel utilization device that normally receives fuel in excess of its requirements, the system automatically assuring that the excess fuel is returned to the fuel tank from which it was supplied. With such a system, the operator is able to select at will from which tank fuel will flow, and to shift flow at any time while always maintaining the return flow of excess fuel to the particular tank from which it originated.

Claims (6)

1. A manually controllable switching system for selectively controlling the flow of fuel from a plurality of fuel tanks to a fuel utilization device comprising, in combination, first and second fuel sources adapted to be supplied with fuel under pressure from first and second fuel tanks, respectively, each adapted to have a fuel pump therein rendered operable or inoperable at will, first tank and second tank fuel supply lines respectively connecting the first and second sources to the fuel utilization device, a third fuel distribution line common to and connected at one end to both of the first tank and second tank fuel supply lines and at its other end adapted to be connected to the device to supply the device with fuel from either of the tanks, a fuel return flow line adapted to be connected at one end to the device and common to and connected at its other end to first tank and second tank branch fuel return flow passages adapted to be connected respectively to the first and second fuel tanks for returning excess fuel flow from the device to the respective tank from which it was supplied, a shuttle valve mechanism operably movably associated within the first tank and second tank fuel supply lines and return flow passages for directing the supply of fuel to and return of excess fuel from the device separately to and from each of the tanks, the valve mechanism including a reciprocably movable shuttle valve movable from one position blocking flow through the first tank supply line and first tank return flow line while permitting flow through the second tank supply line and second tank return flow line, and vice-versa upon the valve being reciprocated to its alternate position, and fuel pressure sensitive means responsive to the differential in pressure between the first and second fuel tanks applied to the pressure sensitive means to shift the shuttle valve between its positions as a function of whichever fuel tank pressure is higher, upon the selective rendering operable of one of the other of the fuel pumps.

2. A system as in Claim 1 wherein the pressure sensitive means comprises a servo mechanism including a housing partitioned into first tank and second tank pressure chambers by a flexible diaphragm, first and second conduit means connecting the fuel respectively from the first tank and second tank supply lines to the first and second pressure chambers, and means operably connecting the diaphragm to the shuttle valve for moving the valve.

3. A system as in Claim 2, including an over-center spring mechanism connecting the diaphragm to the valve to provide a snap action movement of the valve from its one position to its alternate position.

4. A system as in Claim 2 or 3 wherein the rendering operable of the fuel pump in the first tank while maintaining the second tank fuel pump inoperable supplies fuel under pressure to the first tank supply line and first tank chamber of the servo mechanism to move the shuttle valve to supply fuel from the first tank to the utilization device and to return excess fuel from the device only to the first tank, the rendering operable of the fuel pump of the second tank while rendering inoperable the first tank pump supplying fuel under pressure from the second tank supply line to the second tank servo mechanism chamber to switch the shuttle valve to its alternative position supplying fuel to the device from the second tank and returning excess fuel from the device only to the second tank.

5. A system as in any preceding claim, the shuttle valve mechanism including a valve housing having a valve reciprocably movable therein and having a plurality of spaced lands interconnected by neck portions of reduced diameter, the housing having a first pair of inlets receiving fuel from the first tank and second tank supply lines respectively and a first pair of outlets connecting the fuel respectively from the first inlets to the device, and a further inlet for receiving return fuel flow from the device and a further pair of outlets connecting the further inlet respectively to the first tank and second tank return fuel flow branch passages, movement of the valve to the one position connecting the first tank fuel to the device and returning excess fuel to the first tank while blocking the flow of fuel from the second tank to the device and the return of fuel from the device to the second tank.

6. A manually controllable switching system for selectively controlling the flow of fuel from a plurality of fuel tanks to a fuel utilization device, constructed arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.