WO2003044335A1

WO2003044335A1 - Dual fuel carburettor

Info

Publication number: WO2003044335A1
Application number: PCT/AU2002/001564
Authority: WO
Inventors: Dominic De Carlo
Original assignee: Autoclima Pty. Limited
Priority date: 2001-11-16
Filing date: 2002-11-18
Publication date: 2003-05-30

Abstract

A carburetion system for an internal combustion engine including a carburettor (6), a petrol input through which petrol can be passed to a float chamber (40) associated with the carburettor (6), means whereby the petrol flow can be selectively delivered into the carburettor (6), a gas input having means whereby gas can be selectively delivered into the carburettor (6), and an oil input which includes means whereby oil can be fed into the flow of petrol and/or gas and air prior to the entry of the fuel into the engine.

Description

DUAL FUEL CARBURETTOR

Area Of The Invention

This invention relates to a dual fuel carburettor. It is well known, particularly in the automotive industry, to have vehicle engines operating on dual fuels, 5 normally petrol and liquid petroleum gas although it has been proposed to use petrol and compressed natural gas. This art is relatively well developed and widely applied

Background To The Invention.

There are many applications where two stroke engines are used and it has ιo generally not been possible to provide dual fuel operation for these. This is because two stroke engines generally operate on a dry sump and the lubricating oil necessary to maintain the engine components is supplied by being mixed into the petrol.

The petrol/oil mix generally passes to the cylinder or cylinders by way of the i5 crank case and through a port in the side of the cylinder so the various operating components in the crank case have oil supplied thereto and, at the same time, oil is supplied to the cylinders to reduce friction between the piston rings and the cylinder walls.

Because LPG is held under pressure, if oil is mixed with LPG this will separate ₂o out in the cylinder and, generally, because. the LPG is cold the oil will tend to become dense or even to solidify. Thus, when the gas is being delivered to the vehicle, it would not have any oil entrained with it. There is also a possibility that the oil could clog the piping and jets. Because of this it has not been feasible to provide a dual fuel two stroke engine which would be desirable from the point of view of lessening the noxious emissions to air which are normally associated with the use of two stroke engines. Despite this two stroke engines are widely used in motor cycles, lawn mowers and outboard motors as well as in many fixed situations for operating other equipment.

Outline of the Invention

It is an object of the present invention is to provide a carburetion system whereby two stroke engines can be readily used with dual fuels and which system may well have other applications.

The invention in one aspect is a carburettor for an internal combustion engine said carburettor having a body having a passageway therethrough, a float chamber to receive petrol from a petrol input, said carburettor having means whereby petrol can be selectively input into the body of the carburettor, means whereby gas can be selectively input into the body of the carburettor and an oil input means to the body of the carburettor whereby oil can be fed into the flow of a mixture of petrol and air, or gas and air, prior to entry of this mixture into the engine.

The invention in another aspect includes a carburetion system for an internal combustion engine including a carburettor, a petrol input through which petrol can be passed to a float chamber associated with the carburettor, means whereby the petrol flow can be selectively delivered into the carburettor, a gas input having means whereby gas can be selectively delivered into the carburettor, and an oil input which includes means whereby oil can be fed into the flow of petrol and/or gas and air prior to the entry of the fuel into the engine. The oil may be adapted to be used only with gas whilst petrol having oil mixed therein is used when petrol is being used as a fuel or, alternatively, the oil could be supplied to the carburettor at all times when the engine is operating to provide the necessary oil for lubrication of the engine regardless of which type of fuel is to be used. In this case normal petrol rather than a two stroke oil and petrol mix may can be used.

In order that the invention may be more readily understood we shall describe one particular form of carburettor made in accordance with the invention but it is to be understood that this is a preferment and the physical arrangement and the operative components of the carburettor can vary widely.

Brief Description of the Drawing Figures

Fig. 1 Is a schematic diagram showing the component parts of a system for a dual fuel system engine using the carburettor of the invention.

Fig. 2 Shows a vertical cross-section through the carburettor;

Fig. 3 Shows a schematic cross-section through the needle plate of the carburettor;

Fig. 4 Shows a schematic diagram of the reducer/regulating gas input device of the invention.

Description of a Preferred Embodiment of the Invention

With reference to Figure 1 , a system is provided for the conversion of a small internal combustion engine to operate on LPG fuel, comprising LPG fuel storage tank 1 associated with liquid to gas converter 2 being a combination reducer regulating valve ; LPG fuel pressure regulator 4; oil storage tank 5 with filler cap 37 and contents sight gauge 38; petrol storage 3 and solenoid valve 28; combined gaseous fuel carburettor and lubricator 6; solenoid shut-off valves 7,8 respectively in LPG fuel and oil supply lines; electronic control unit 9; power supply line 17 and battery 10; magneto 11; spark plug 14; generator 12; starting module 68; LPG fuel supply line 15; oil supply line 16; shut-off valve control leads 18, 19;

For the purpose of this description we will not take into account any of the normal sophistications of a carburettor such as, for example, the idle jets or other arrangements to permit correct idling at the required engine speed. Neither will we detail any form of compensation for load or atmospheric temperature or pressure or any pump arrangements to ensure that there is an increased loading of fuel when necessary when acceleration is required.

These are all well known in the carburettor art and can be applied as required for a particular application.

As shown in Figure 2 the carburettor 6 has a body 22 having an air passageway 30 through it. This body 22 associates with a float chamber 40 to receive petrol from a petrol input.

This input is associated with a solenoid valve which can either be open, to permit petrol flow or closed, to prevent any flow.

When the solenoid is open, petrol can flow through into the float chamber at, and which has a float operating a valve so that the petrol flow is controlled so that the petrol level in the chamber is effectively maintained constant.

Associated with this chamber, there can be a main jet 41 which permits petrol to be drawn into passageway 30 due to the venturi effect of air being drawn into the engine. This causes petrol to be entrained with the air so that a required charge of petrol/air is formed and delivered to the engine.

The carburettor also has a gas input and again the normal sophistications of supplying gas to an engine will not be discussed herein, they are known to the art and would be readily able to be applied by persons skilled in the art. It is preferred that LPG be used but any appropriate gas could also be used.

Again, the LPG is provided with a main jet through which the required quantity of gas can be provided to the passageway 30 of the carburettor and be entrained in the air necessary for combustion.

In the carburettor of the invention we also provide a third inlet and jet and this is for oil.

As mentioned earlier, when gas is being used it is essential that oil be supplied separately from the gas so that it maintains its liquidity and can be atomised to provide the necessary fluid for lubrication of the moving parts of the engine. In this case, the oil supply is provided through the third jet which in common with the other two, is located in the path of the air, in the base of the passageway 30 of the carburettor, so that a required quantity of oil in the form of an atomised mist can be entrained in the air for delivery into the engine.

The arrangement of the jet and the venturi by the means of which the oil is drawn therethrough and mixed with the air is controlled to provide the required quantity of oil for delivery.

As shown in Figures 2 and 3 the carburettor 6 has a shutter device, for controlling the air flow through the carburettor, attached to shaft 50 which is moveable in the vertical through the carburettor and is connected to horizontal plate 51 which supports needles 60, 61 and 62 which cooperate with needle valves 63, 64 and 65 respectively which are located in the base of the carburettor passageway. These needles and valves control the rate of flow into passageway 30 of oil, petrol and gas respectively. Of course should either the gas or petrol be turned off the position of the relevant needle would not have any functional effect on the carburettor.

In operation the engine may be started on petrol and, if so, this is selected and when the solenoid is opened a petrol pump drives petrol into the chamber 40 where it reaches a level at which a float prevents ingress of further petrol. As air passes the petrol venturi it entrains petrol and this passes into the crank case of the motor. Once the engine is running this operation continues.

If the petrol is not provided with oil therein the oil flow is also enabled and the air moving passed the oil venturi will cause this to atomise and to be also passed into the crank case together with the petrol entrained in the air to provide the lubricating fluid for the moving parts in the crank case and, when passed with the petrol into the combustion chamber, for the lubrication of the cylinder walls and piston means.

If the engine is to be run on gas then the petrol solenoid is closed, the gas valve is opened and gas is fed into the carburettor in the normal way.

At the same time, the oil supply is enabled so that oil is atomised and fed together with the gas into the crank case of the engine to provide the required lubrication as previously discussed.

Another feature of the invention shown in Figure 4 is the gas reducer/ regulating and safety valve 2 which comprises an inlet 70 which is in direct connection to the gas tank and within this there is a sliding member 71 having a valve 72 which can act against a seat not shown in passage 73.

The sliding member can be acted upon directly by a solenoid the corner of which is located thereabouts so that, when the engine is to operate on gas, the solenoid is operated, the valve 72 moves away from its seat and high pressure gas can pass into the high pressure chamber.

High pressure gas is passed outwardly and is converted to a low pressure form which enters into the low pressure chamber 75.

In the low pressure chamber there is a spring 76 and an adjustment screw 77 to provide the required pressure on a plate 78 for the particular engine with which the device is being used.

Under normal operation the low pressure gas is of a pressure greater than necessary to move the plate 78 away from its seat 79 so gas can pass into the low pressure chamber 75 and thus to an outlet which is in connection with the carburettor.

The plate 78 will move with variations in demand from the engine and this movement can permit a greater or lesser quantity of liquid to be gasified and passed through the system.

When demand is low, then the amount of gas permitted to pass into the low pressure chamber 75 is reduced. The engine provides continuous pulses to act on the solenoid to enable the sleeve 71 to be moved to permit the valve 72 to be spaced from its seat and high pressure gas passed into the high pressure chamber 74.

When it is not required to operate the engine on gas or should there be a break in the outlet line which causes the engine to stop then the solenoid does not receive the required pulse from the engine and ceases to act on the slide 71 which moves forward under gas pressure and closes the valve. Thus the device permits both control flow of low pressure gas to the engine and also acts as a safety device should there be any break in the line between the device and the carburettor.

It will be seen that the carburettor of the present invention can provide great flexibility in the operation of two stroke engines and permit them to be satisfactorily run with gas which has not previously been possible, and yet adds little to the total cost of the carburettor.

It is stressed, as mentioned before, that the particular physical form of carburettor is not of substantial importance, it would be possible to provide many forms of carburettor without departing from the spirit and scope of the invention.

Claims

The claims defining the invention are as follows:

1. A carburettor for an internal combustion engine said carburettor having a body having a passageway therethrough, a float chamber to receive petrol from a petrol input, said carburettor having means whereby petrol can be selectively input into the body of the carburettor, means whereby gas can be selectively input into the body of the carburettor and an oil input means to the body of the carburettor whereby oil can be fed into the flow of a mixture of petrol and air, or gas and air, prior to entry of this mixture into the engine.

2. A carburettor as claimed in claim 1 wherein the gas is LPG.

3. A carburettor as claimed in claim 1 wherein oil is supplied to the carburettor at all times when the engine is operating to provide the necessary oil for lubrication of the engine regardless of whether petrol or gas is being used.

4. A carburettor as claimed in claim 3 wherein the input of gas, petrol and oil to the carburettor body is governed by the venturi effect of air passing over jets supplying gas, petrol and oil.

5. A carburetion system as claimed in claim 4 wherein the input of petrol to the carburettor is controlled by a solenoid valve such that the flow can be on or off.

6. A carburettor as claimed in claim 4 or claim 5 wherein the input of gas to the carburettor is controlled by a solenoid valve such that flow can be on or off.

7. A carburettor as claimed in any one of claims 1 to 6 wherein the carburettor is provided with means entering the passageway for supporting needles which interact with needle valves in a base of the passageway, the position of the needles relative to the needle valves acting to regulate the flow into the passageway of gas, petrol and oil.

8. A carburettor as claimed in claim 1 wherein petrol having oil mixed therein is used when petrol is being used as a fuel.

9. A carburettor substantially as herein described with reference to the accompanying drawings.

10. A carburetion system for an internal combustion engine including a carburettor, a petrol input through which petrol can be passed to a float chamber associated with the carburettor, means whereby the petrol flow can be selectively delivered into the carburettor, a gas input having means whereby gas can be selectively delivered into the carburettor, and an oil input which includes means whereby oil can be fed into the flow of petrol and/or gas and air prior to the entry of the fuel into the engine.

11. A carburetion system as claimed in claim 10 wherein the gas input is provided by a combination reducer/regulator valve having a high pressure gas input, a valve means whereby high pressure gas flow can be controlled, a pressure reducing means and a regulating valve which is responsive to gas requirements of the carburettor.

12. A combination reducer/regulator valve having a high pressure gas input, a valve means whereby high pressure gas flow can be controlled, a pressure reducing means and a regulating valve which is responsive to gas requirements of the carburettor.