GB2143618A

GB2143618A - Automatic changeover valve unit

Info

Publication number: GB2143618A
Application number: GB08307530A
Authority: GB
Inventors: John Graham Halberg
Original assignee: BERGMAN ACTUATORS Ltd
Current assignee: BERGMAN ACTUATORS Ltd
Priority date: 1983-03-18
Filing date: 1983-03-18
Publication date: 1985-02-13
Also published as: GB8307530D0; GB2143618B

Abstract

An automatic changeover valve unit for changing a liquid flow system from a main supply tank to a reserve tank comprises a float chamber 18 having an inlet 19 for receiving liquid from a main tank and an outlet 21, a switching valve 24 moveable between a first position in which liquid from the float chamber is directed into a liquid flow conduit 12 when the float is in the raised position and in which some 19 liquid charges the reserve tank and a second position in which an outlet conduit from the reserve tank is connected to said liquid flow conduit 12 and the reserve tank is vented. <IMAGE>

Description

SPECIFICATION Automatic changeover valve unit This invention relates to changeover valve unit for automatically changing a liquid flow system from a main supply tank to a reserve tank when the main tank becomes empty. Preferably the liquid flow system is a fuel system and preferably a fuel system of an internal combustion engine.

It is known to provide a liquid flow system with a main tank and a reserve tank and to provide a switching valve unit which switches the system to the reserve tank when the main tank becomes empty. However such switching valve units are not usually automatically operated and there is always the possibility that air is drawn into the system when the main tank empties. In fuel systems for internal combustion engines, particularly Diesel engines, the introduction of air into the fuel system means that the system has to be re-primed before the engine can be started. This can be a time consuming and difficult job and if the engine is used for powering a motor vehicle, the vehicle may have to be moved to a garage for the work to be carried out.

According to the present invention there is provided a changeover valve unit for automatically changing a liquid flow system from a main or one supply tank to a reserve or second tank comprising a float chamber having an inlet for receiving liquid from a main or one tank and an outlet, a switching valve movable between a first position in which liquid from the float chamber is directed into a liquid flow conduit when the float is in a raised position and in which some of the liquid charges the reserve or second tank and a second position in which an outlet conduit from the reserve or second tank is connected to said liquid flow conduit and the reserve tank is vented.

Preferably the switching valve is moved by a float in said float chamber. Alternatively the switching valve is moved by a solenoid and the float used to actuate an electrical switch for actuating the solenoid.

An embodiment of the present invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure lisa diagrammatic illustration of a liquid flow system provided with a valve unit according to the present invention, Figure 2 is a diagrammatic illustration of the valve unit, Figure 3 illustrates an alternative form of switching valve which can be used in the valve unit, and Figure 4 illustrates another a Iternative form of switching valve which can be used in the valve unit.

The liquid flow system shown in Figure 1 comprises a main storage tank 10 for liquid, such as a liquid fuel, having an outlet conduit 11 connected to a main liquid flow conduit 12 through a changeover valve unit 13 according to the present invention. The liquid flow conduit 12 is connected to a pump 14. The valve unit 13 is preferably fitted into a reserve tank 17, conduits 15 and 16 being used to fill and draw-off from the reserve tank 17, or alternatively the unit 13 can be external of the reserve tank 17 as shown.

The changeover valve 13, as shown in Figure 2, comprises a float chamber 18 having an inlet 19 connected to the outlet conduit 11 of the main tank 10. Located within the float chamber 18 is a float 20 and the float chamber 18 has an outlet 21. The outlet 21 is connected to a conduit 22 having a non-return valve 23 and the conduit 22 is connected via the conduit 15 to the reserve tank 17. The outlet 21 is also connected to a changeover valve 24 having a port 25 which communicates through the valve 24 with an outlet port 26 connected to the liquid flow conduit 12. The changeover valve 24 also has a port 27 connected to the conduit 16 and which can be connected through the valve 24 to the port 26 and thus conduit 12.The changeover valve 24 has a movable valve member 28 which at its upper end is connected to one end of a lever 29 which is pivoted at 30 and the other end is connected to the float 20.

The float chamber casing is provided with a bleed screw 31 and with an electrical switch 32. A conduit 33 is fitted to the top of the reserve tank 17 and extends to the top of the main tank 10 to act as a bleed or breather pipe.

As shown in Figure 3 the movable valve member 28 can be in the form of a flat plate provided with a hole, or as shown in Figure 4, the movable valve member 28 can be in the form of a pivoted valve plate.

On initially filling the main tank 10 and priming the fuel flow system the bleed screw 31 is removed and the lever 29 is pushed down to lift the float 20 to allow liquid to flow from the tank 10 and through the valve 24 to the conduit 12. Some of the liquid will flow through the non-return valve 23 and conduits 22 and 15 to fill the reserve tank 17 and conduit 16 up to the port 27. Any air is vented through conduit 33 to the main tank. Any air trapped in conduit 16 up to the port 27 will be extracted by means of an air extractor fitted in conduit 12.

The engine which is fed with fuel by the pump 14 can then be started. Fuel in the main tank 10 flows through the float chamber 18 and outlet 21 and passes through the port 25 and through the valve member 28 to the port 27 and into the conduit 12.

When the main tank 10 becomes empty the float 20 will be lowered and via the lever 29 the valve member 28 will be lifted connecting the port 27 and the conduit 16 to the port 26 and conduit 12 and fuel will then be withdrawn from the reserve tank 17. The tank 17 will be vented through the conduits 15,22 and non-return valve 23. When the main tank 10 is empty the supply conduit then becomes the breather conduit for the unit 13. The air is cut off from the float chamber 18 giving a pressurized mode to the reserve tank 17 and liquid will flow from the reserve tank 17 until the main tank 10 is replenished cutting off the air.When the main tank 10 is replenished fluid will then flow into the float chamber 18 and the float 20 will rise and via the lever 29 the valve member 28 will be lowered cutting off the flow from port 27 and the reserve tank 17 will now refill through conduits 22,15 until required again.

When the valve member 28 is raised to allow liquid to be taken from the reserve tank 17 the switch 32 is operated to give an audible and/or visual indicated.

An auxilliary pump can be fitted for use in the event of failure of the main pump 14 and an air extraction unit can be fitted to conduit 12 for use with Diesel engines, fuel injection engines. The fuel flow system may comprise an oil fired central heating system.

The example is described for use with fuel systems for petrol or Diesel engines or oil fired fuel systems but the unit of the present invention can be used with any fluid system, i.e. water, hydraulic fluid or chemical systems.

Claims

1. An automatic changeover valve unit comprising a float chamber, with float, having an inlet for liquids from a first or main tank and an outlet, conduits to supply liquids to and allow venting of liquids from a second or reserve tank, a valve moveable between two positions, a lever connecting the moveable valve to the float, and an exterior outlet.

2. An automatic changeover valve unit as claimed in claim 1 wherein is provided an uninterrupted flow of liquid sequentially from two tanks to an outlet port.

3. An automatic changeover valve unit as claimed in claim 1 and claim 2 wherein when liquid flow from a first or main tank is depleted fluid from a secondary or reserve tank will be drawn automaticalliy through the unit to the outlet port.

4. An automatic changeover valve unit as claimed in claim 1 and claim 2 and claim 3 wherein is provided that when the first or main tank is replenished with liquid the flow to the outlet port will revert from the reserve or secondary tank to the first or main tank.

5. An automatic changeover valve unit as claimed in claim 1 and claim 2 and claim 3 and claim 4 wherein is provided that the outlet port is secured against contamination by ingress of air during the changeover of flow of liquid between the two tanks.

6. An automatic changeover valve unit as claimed in claim 1 and claim 2 and claim 3 and claim 4 and claim 5 wherein liquid flow is uninterrupted at the outlet port during changeover of flow between tanks.

7. An automatic changeover valve unit as claimed in claim 1 and claim 2 and claim 3 and claim 4 and claim 5 and claim 6 wherein any depletion of the second or reserve tank will be replenished automatically when the first or main tank is replenished.

8. An automatic changeover valve unitsubstantially as described herein with reference to Figures 1-4 of the accompanying drawing.