GB2076890A

GB2076890A - Engine fuel supply and storage systems

Info

Publication number: GB2076890A
Application number: GB8112031A
Authority: GB
Original assignee: Komatsu Ltd
Current assignee: Komatsu Ltd
Priority date: 1980-04-18
Filing date: 1981-04-16
Publication date: 1981-12-09
Also published as: GB2076890B; DE3115504A1; JPS56154227U; JPS6119938Y2

Abstract

A first fuel tank 1 contains a level detector 13 and is connected by a pipe 5 to an engine fuel pump 4. A second tank 2 has a number of outlets controlled by float valves 8 leading through a one- way valve 7 to the tank 1. When the fuel level in the tank 1 falls below a certain level L, the detector 13 produces a signal to a controller 22 which causes fuel to flow from the tank 1 to the tank 2 by a pump 11 or by connecting the tank 2 to a source of compressed air. A float or pressure switch 20 provides a signal to the controller 22 when the tank 2 is empty and below the level L in the tank 1 a signal from the detector 13 actuates an alarm. <IMAGE>

Description

SPECIFICATION Fuel storage systems The invention relates to fuel storage systems suitable for an engine in a road vehicle.

The size of the fuel tank needed in a vehicle increases with the size of the vehicle. There are cases where the fuel tank has to be divided or separated into two or more units because of the space available. This has necessitated a change-over valve requiring manual operation, and has made filling troublesome. If the height of the tank is limited by the space available, its horizontal area has to be increased, and it is difficult to form a recessed sump in the bottom and to consume the whole fuel.

The invention provides a fuel storage system for an engine comprising a first tank containing a fuel level detector, a second tank having an outlet for leading fuel to the first tank, a float valve for preventing flow through the outlet when the fuel falls below a certain level, a one-way valve for preventing fuel flow from the first tank to the second, and a controller for causing fuel to flow from the second tank to the first in response to a signal from the level detector.

There may be provided a pump for causing fuel to flow from the second tank to the first, and a motor for driving the pump, or the second tank may have a pipe for connection to pressure from the engine and a solenoid valve in the pipe.

Drawings: Figure 1 illustrates a fuel storage system accord ing to the invention; and Figure 2 another similar system.

In Figure 1, a first tank 1 and a second tank 2 are connected by means of a pipe 3. The first tank 1 is nearly the same size as an ordinary small-sized tank, and has a recessed fuel sump la in the bottom from which a pipe 5 leads to a fuel injection pump 4 for the engine. At the ends of the pipe 3 are check valves 6 and 7 which permit fluid flow only towards the first tank 1. The second tank 2 is larger than the first tank 1, in particular in the horizontal plane, and has a flat bottom. The second tank 2 has float valves 8 mounted in the four corners of its bottom, and the outlets of the float valves 8 are connected to a collection pipe 9. The collection pipe 9 is connected to the pipe 3 through a pump 11 driven by a motor 10.

In the upper part of the first tank 1 are an air vent 12 provided with a float valve, an electrical level detector 13, a solenoid-operated air vent valve 14 and a fuel return pipe 15 extending from the fuel injection pump 4. The first tank 1 also has a solenoid-operated water drain valve 16 in the bot atom. In the upper part of the second tank 2 are a fuel inlet port 17 and an air vent 18 provided with a float valve. In the side of the second tank 2 is another fuel inlet port 19 which is used for filling fuel under pressure. The collection pipe 9 is provided with a float switch 20, and the end of a pipe extending to the fuel inlet port 19 for filling fuel under pressure has a quick charge receiver 21.

A controller 22 powered by a battery 23 is, connected with the level detector 13, the solenoid air vent valve 14, and the solenoid water drain valve 16 of the first tank 1, and with the motor 10 and the float switch 20 of the second tank 2, and can control these components automatically or manually.

In order to fill the tanks 1 and 2, fuel may be fed by gravity through the inlet port 17 of the second tank 2, or under pressure through the other fuel inlet port 19.

In gravity filling, the fuel is supplied with the switch of the controller 22 either at an automatic or manual run position for driving the motor 10 so that the fuel supplied into the second tank 2 may be transferred into the first tank 1 by the pump 11.

When the fuel fed into the first tank 1 has reached its highest level, the level detector 13 stops the motor 10 in automatic operation. In manual operation, the operator may detect a signal generated by the level indicator 13, and stop the motor 10 by switching it off. If the second tank 2 is not filled to its maximum level, the fuel filling operation can be continued further until the highest level is reached. Although the transfer of the fuel from the second tank 2 into the first tank 1 is by way of the check valves 6 and 7 which are set so as not to open under the pressure differential created by the head due to a difference in mounting position when they are attached to the vehicle body, or to an inclination of the vehicle body, for example.

In pressure filling, a fuel filling gun 24 is connected to the quick charge receiver 21 leading to the fuel inlet port 19, and so fuel is charged into the second tank 2. When the fuel has reached the maximum level of the second tank 2, the float valve of the air vent 18 is shut off. The pressure in the second tank 2 increases and opens the check valves 6 and 7, so that fuel is transferred through the pipe 3 into the first tank 1. When the first tank 1 has been filled to its maximum permissible level, and the float valve or the air vent 12 is shut off, the pressures within the tanks 1 and 2 will rise to such a degree that further filling by means of the gun 24 is not possible, and filling is automatically stopped.

When fuel in the first tank 1 has been consumed by the engine, and has reached a level L in the detector 13, a float switch which is located at the corresponding position in the level detector 13 is actuated and energizes a control circuit within the controller 22.

The motor 10 is driven and transfers fuel from the second tank 2 into the first tank 1. When the first tank 1 is filled with fuel to its maximum level, a float switch installed at U in the upper part of the level detector 13 will stop the motor 10 and hence the pump 11 through the action of the controller 22 so that the fuel transfer is interrupted. Such operations are repeated several times so that the fuel in both tanks 1 and 2 is consumed. When the second tank 2 has become empty, all the float valves 8 will be shut off and the collection pipe 9 will become empty. This is detected by the float switch 20 and stops the motor 10. The motor 10 is kept deenergized even when the fuel in the first tank 1 has reduced to the L position of the level detector 13, and actuates the float switch at that position.The fuel in the first tank 1 reduces to an extreme low position EL, and a float switch at the corresponding position in the level detector 13 is actuated to sound a remnant alarm buzzer on the controller 22.

The float switch 20 in the collection pipe 9 may be replaced with a pressure switch 50 that when the collection pipe 9 has become empty the decrease in delivery pressure of the pump 11 can be detected to find out that the collection pipe 9 and hence the second tank 2 have become empty.

When an engine check or inspection is made, a water drain switch mounted on the controller 22 is depressed by the operator to open the solenoidoperated water drain valve 16 of the first tank 1 for a period to draining off any water accumulating in the bottom of the tank. The solenoid air vent valve 14 fitted to the first tank 1 is interlocked through the controller 22 with the engine switch. Therefore, the air vent 14 is kept open when the engine is being driven so that a back pressure is not applied to the fuel in the pipe 15 returning from the fuel injection pump 4.

If the vehicle having the fuel tanks is inclined during running of the engine, no shortage of fuel to be supplied to the engine will occur because the first tank 1 has the recessed fuel sump 1a in the bottom.

Further, because the second tank 2 has outlets with float valves 8, even when some of the outlets are exposed in the air, the exposed float valves 8 are closed and allow fuel to be supplied from other non-closed outlets of the second tank 2 into the first tanks.

In the arrangement of Figure 2, the fuel transfer is effected without any motor or pump. A collection pipe 9' is connected to the float valves 8 in a second tank 2' connected directly through the check valve 7 to a first tank 1. The second tank 2' is connected to a back-pressure pipe 27 through a relief valve (not shown) and a solenoid valve 26 with a pressure generating portion of the engine, for example the turbo charger back-pressure chamber or an air compressor. When the fuel in the first tank 1 has been consumed by running of the engine and has reached a predetermined level, the solenoid valve 26 is opened to allow a back-pressure (of about 2 kg/cm2) from the engine to be introduced into the second tank 2' and to work on the surface of the fuel so that the downward urging force thus produced transfers the fuel from the second tank 2' into the first tank 1. When the first tank 1 has been filled with the fuel to its maximum level, the solenoid valve 26 is shut off.

Thus the fuel from one tank can be automatically transferred into another tank, so there is no need for a change-over valve, and the two separate tanks can be used as if they were a single or integral fuel tank.

The outlet float valves 8 make it possibleforthe whole of the fuel stored in the first and second tanks 1 and 2 to be consumed for driving the engine.

Claims

1. A fuel storage system for an engine comprising a first tank containing a fuel level detector, a second tank having an outlet for leading fuel to the first tank, a float valve for preventing flow through the outlet when the fuel falls below a certain level, a one-way valve for preventing fuel flow from the first tank to the second, and a controller for causing fuel to flow from the second tank to the first in response to a signal from the level detector.

2. A system according to claim 1 in which the second tank has a number of outlets leading to the first tank, each controlled by a float valve.

3. A system according to claim 1 or claim 2 in which the second tank has a gravity fuel inlet and a quick charge fuel inlet.

4. A system according to any preceding claim including a pump for causing fuel to flow from the second tank to the first, and a motor for driving the pump.

5. A system according to any of claims 1 to 3 in which the second tank has a pipe for connection to pressure from the engine and a solenoid valve in the pipe.

6. A fuel storage system as herein described with reference to Figure 1 or Figure 2 of the drawings.