GB2076889A - Feeding fuel and water emulsion to i.c. engines - Google Patents

Abstract

An air vent tank 32, with a float valve 36, is provided in the return line 30 to the emulsifier 14 from the injectors 28. The emulsifier 14 receives water from a gravity tank 18 through a metering orifice 24. A solenoid valve 22 prevents water flow for a predetermined period after engine starting. <IMAGE>

Description

SPECIFICATION Improvements relating to internal combustion engines This invention relates to internal combustion engines which have a fuel supply system set up to supply the engine with an emulsion of fuel and water, and generally speaking the invention can be applied to all forms of internal combustion engines More specifically, however, the invention provides two aspects concerning the fuel and water emulsion supply system. One aspect relates only to internal combustion engines having fuel overspill, be this a trickle overspill such as 1 to 2% and up to 10% or a high overspill, as much as of the order of 70%.

Overspill engines are usually diesel engines having fuel injectors and overspill is used on the one hand to ensure that the injector pumps stay full and to ensure that air or other gas drawn into the injector is vented. A high overspill is additionally used for cooling of the injectors. The overspill is returned to the fuel tank which provides the vent but this is not possible when an emulsion is being used.

The second aspect of the invention relates to any type of internal combustion engine petrol or diesel, as it relates to the manner of feeding the water to the fuel supply system.

It is of course well known to emulsify diesel fuel and water, to produce an emulsion which is supplied to the engine, the main purpose behind the utilisation of water being of course to economise in the fuel.

Because water, a non-combustible liquid, is being introduced into the engine, care must be taken to ensure that the supply of the emulsion is kept under control, and in fact we have been working in this field on the basis of the disclosure of the invention in co-pending British Application No. 33551/77, the proposal of which is that the ratio of water to fuel in the emulsion should be controlled such that with increasing fuel demand, for example with increased speed demand, the percentage water in the emulsion should decrease, and in fact in the said specification it is proposed that the flow of water should be maintained substantially constant.

Over a period of several years in working with this system, and in attempting to make it as effective as possible, the two inventive aspects mentioned herein have been developed and form the subject of the present invention.

As mentioned, the first aspect applies to an engine with fuel overspill, which in fact is an engine of the type in which, when fuel is supplied to the engine, it is supplied in a quantity greater than that required for the combustion conditions. The overspill from the engine is returned to the fuel supply system via a return line.

When the engine runs on a fuel/water emulsion, the return line must be returned to a position at or after the mixing of the incoming fresh fuel and water and this return line has shown itself to be a source of difficulty in so far as pockets of air arise, in the line, which eventually can lead to stalling of the engine. It should be mentioned that the said return line has a fall from the engine back to the fuel supply system.

In accordance with the first aspect of the invention, an internal combustion engine of the type in which there is fuel overspill, is set to be supplied with an emulsified fuel/water mixture and has a return line for the overspill connected to a point in the supply system at or after the point of mixing of incoming fresh fuel and water, and wherein there is in the return line, a surge tank having a vent to atmosphere and preferentially a valve so that flow from the tank back to the fuel supply system is terminated in the event of the liquid level in the tank falling to a predetermined level, and is opened when the said level rises to a second predetermined upper level.

The vent enables the escape of air and the prevention of the creation of a vacuum in the return line.

When this arrangement is used with a high overspill engine, the emulsion returned from the surge tank may pass directly to the emulsifier of the system or to some other point in the supply system after the emulsifier. With this system a water feed pump can be used.

In the said co-pending application, a water pump was used for the delivery of a constant volume of water to the emulsifier, and it was discovered that it might be possible to dispense with the pump, and in accordance with another aspect of the invention therefore the water feed pump is eliminated, and the water is arranged to flow to the supply system, for example to the emulsifier, under gravity, the water line preferably including a metering orifice in order to maintain the flow of water substantially constant or within limits, during the running of the engine over its entire speed range. The said water line may also include a solenoid valve, which acts as an on-off device to permit or prevent the flow of water through the line depending upon whether or not the vehicle ignition is switched on or switched off.This aspect of the invention can be used with internal combustion engines with or without overspill.

The fuel supply line may lead from a fuel tank, through a filter and to the emulsifier, the emulsifier including an emulsification rotor which is driven automatically when the vehicle engine ignition is switched on and stops when the ignition is switched off. The said water and fuel lines may enter the emulsifier through different ports, or through the same ports, in which case the water and fuel lines may meet before the water and fuel enters the emulsifier. The emulsion which is returned from the engine, when provided with an overspill arrangement as mentioned above, may enter the emulsifier to be mixed with the fresh incoming fuel and water, through a separate port.

In a composite system involving a high overspill diesel engine such as a Cummins (Registered Trade Mark) engine, advantageous results have been obtained with-the gravity feed water system indicated above and the surge tank arrangement also indicated above, being the two aspects of the present invention. The said aspects in combination provide an extremely effective system when used with an overspill type engine.

An embodiment of this composite aspect of the present invention will be described, by way of example, with reference to the accompanying diagrammatic drawing, which indicates in schematic form the layout of the fuel and water supply system for an engine which runs on an emulsion of water and fuel.

Referring to the drawing, reference numeral 10 indicates a diesel fuel tank, from which extends a fuel line 12to an emulsifier 14, the fuel line 12 including afilter 16.

Numeral 18 represents a water tank, and numeral 20 represents a water line extending from the tank 18 to the emulsifier 14, the said line having a solenoid valve 22 and a metering orifice 24, the latter serving to control the flow of water from the tank 18 to the emulsifier 14to keep the flow in use as constant as possible, as will be explained hereinafter. It is to be noted that the water tank is located above the emulsifier by the height H in order that it will have sufficient head to enable the water to feed under gravity to the emulsifier 14. The emulsifier may be of any suitable construction, such as for example described in US Patent Specification NO.4172668.

The water and fuel are emulsified in the emulsifier 14 and the emulsion is ejected from the emulsifier by the rotary action, and an injector pump 26 draws it in and delivers it under pressure to injectors 28 which inject the emulsion into the cylinders of the engine in conventional manner. The excess emulsion supplied to the injectors 28 may be a trickle or may serve to cool the injectors 28 and may be as high as 70%, and is returned to the emulsifier through a return line 30, said return line 30 including a surge tank 32 which has an air vent 34 and a float control valve 36. The tank 32 is of such a size as to be able to dissiple some of the heat out of the overspill fuel emulsion, but it should not be so large as could cause settling out of the water from the emulsion. The tank 32 would be cooled to remove heat from the overspilled emulsion.

Line 30 enters the surge tank 32 at the top thereof, so that the inflowing return emulsion falls freely through the upper space of the tank 32 to the bottom thereof, and the valve 36 operates to prevent flow of emulsion back to the emulsifier when the level in the tank 32 reaches a predetermined lower level, and opens the outlet when the said level reaches a predetermined upper level. The vent 34 opens from the top of tank 32 and enables any air to escape to prevent the creation of air pockets in the line 30.

Reference numeral 38 represents an electrical control device for the electrical control of the various components described. The control device 38 is connected to the vehicle ignition switch and when the ignition switch is turned on, an electrical signal passes on wire 40 to open an outlet valve in the water tank 18 which normally prevents flow of water through line 20, and a signal on line 42 starts up the prime mover of the emulsifier 14, which may for example be a rotor driven by an electric motor. The line 44 is for energising the solenoid valve 22 to open same, but the said line 44 does not receive the appropriate signal immediately upon switching on of the vehicle ignition, but in fact receives said signal to condition solenoid valve 22 only after the vehicle engine has fired and has been running for a predetermined period.In a specific embodiment of the invention, that period has been set at approximately 1 minute and 20 seconds. When the vehicle ignition is switched on, the engine is turned, and the engine fires, the ensuing rotation of the engine is used as a means for setting a timer, and at the end of the period set by that timer, the appropriate signal is applied on line 44. This aspect of the control is to ensure that no water is supplied to the engine from the water tank 18 during initial starting of the engine.

In using a system as illustrated in the accompanying drawing, the metering orifice 24 was in fact variable and the system was set up by adjusting the size of this orifice during idling conditions over a range of water flows.

Eventually, a water flow of 20cc per minute was found to be the optimum at idling conditions, and the orifice was fixed at this condition for the trials on the road. Surges in water flow and hence variation in waterflowwere observed during running which was probably due to the fluctuation in demand reflected by the intake pressure of the injector pump 26 which draws the emulsion from emulsifier 14 and supplies itto ejectors 28, but the maximum surge observed indicated a water flow of the order of 34cc per minute. The water flow is kept reasonably constant by the use of the orifice 24, and of course with increasing fuel demands at increased speeds, the percentage water in the emulsion reduces. As a rough guide, it is eliminated that at idling conditions as much as 40% of the emulsion will be water, whereas at conditions of or near maximum speed, the percentage water in the emulsion may drop to as littleas 10to 15%.

The system described operated extremely satisfactory and gave very encouraging results, indicating fuel economies in the order of 10 to 30% when the vehicle is used in a manner simulating the normal usage of a delivery vehicle having many stops and starts during a working day.

Claims (1)

1. An internal combustion engine which is sett be run on an emulsion of fuel and water including a water supply line, a fuel supply line an emulsifier for forming an emulsion of fuel and water supplied from said lines, the engine having an overspill line for returning overspill emulsion to be mixed with fresh emulsion, characterised in that in the return line there is a surge tank having a vent to atmosphere and preferentially a valve so that flow from the tank back to the fuel supply system is terminated in the event of the liquid level in the tank falling to a predetermined level, and is opened when the said level rises to a second predetermined upper level.

2. An engine according to clalim 1,wherein the emulsion from the surge tank passes directly tothe emulsifier.

3. An internal combustion engine which is set to be run on an emulsion of fuel and water including a water supply line, a fuel supply line an emulsifier for forming an emulsion of fuel and water supplied from said liners characterised in that there is a water tank located so as to cause gravity feed of the water to the location where it meets the fuel.

4. An engine according to claim 3, wherein the water line includes a metering orifice in order to maintain the flow of water substantially constant or within limits.

5. An engine according to claim 3 or 4, wherein the water line also includes a solenoid valve, which acts as an on-off device to permit or prevent the flow of water through the line depending upon whether or not the vehicle ignition is switched on or switched off.

6. An engine according to claim 3,4 or 5, wherein the emulsifier includes an emulsification rotor which is driven automatically when the vehicle engine ignition is switced on and stops when the ignition is switched off.

7. An engine according to claim 3,4, 5 or 6, wherein the engine has an overspill line for returning overspill emulsion to be mixed with fresh emulsion and there is a surge tank having a vent to atmosphere and preferentially a valve so that flow from the tank back to the fuel supply system is terminated in the event of the liquid level in the tank falling to a predetermined level, and is opened when the said level rises to a second predetermined upper level.

8. An internal combustion engine substantially as hereinbefore described, with reference to the accompanying drawings.

New claims or amendments to claims filed on 7.8.81.

Superseded claims claim 1.

New or amended claims:

1. An internal combustion engine which is set to be run on an emulsion of fuel and water including a water supply line, a fuel supply line an emulsifier for forming an emulsion of fuel and water supplied from said lines, the engine having an overspill line for returning overspill emulsion to be returned to the emulsifier, characterised in that in the return line there is a surge tank having a vent to atmosphere and preferentially a valve so that flow from the tank back to the fuel supply system is terminated in the event of the liquid level in the tank falling to a predetermined level, and is opened when the said level rises to a second predetermined level.