DE3033547A1 - Dual fuel Diesel engine - has speed dependent control giving operation on alcohol at high speeds and on Diesel fuel at low speeds - Google Patents

Abstract

The engine (10) has injectors (14) for diesel fuel from a tank (12). A pump (18) delivers alcohol from a tank (16) through a pressure regulator (20) and a solenoid valve (22) to the inlet valve (24) of an evaporator (26). It is vapourised by heat from the engine cooling water (60) and injected through a venturi (28) into the engine intake air (30). A regulator (34) controlled (36) by the engine speed controls the diesel injection and the alcohol system. Alcohol is used above a given engine speed and diesel fuel below it. The alcohol pump (18) is controlled by the cooling water temperature (62) so as not to pump before there is enough heat available for evaporation.

Description

0335A7

Description:

The invention relates generally to fuel delivery systems for internal combustion engines, and more particularly relates to a method and system for supplying fuel for internal combustion engines.

What came to be known as the energy crisis has led researchers around the world to look for sources of fuel too that can replace the crude oil-based fuel sources. Ethyl alcohol and methyl alcohol are two substances which have attracted attention because on the one hand by coal distillation and on the other hand, among other things repeatedly gained from renewable plant sources can be.

The most varied types of vehicles consume a significant proportion of world production of oil-based vehicles Fuels. Large road vehicles, railways and Ships use diesel fuel in their merit ignition engines and private vehicles use large amounts of gasoline in their gasoline engines. A small amount of diesel fuel is also consumed by private vehicles.

It has been proposed to use ethyl and methyl alcohol as a substitute for gasoline and diesel fuel. In addition, two-fuel systems have already been proposed where some of the gasoline or diesel fuel used for the machine is replaced with an alcohol fuel

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There are several methods of compression ignition machines possible. First, compression ignition engines can make significant engineering changes to the pistons and cylinders including a change in the compression ratio and the additional use of spark plugs to this effect be converted so that they run with pure methyl alcohol or pure ethyl alcohol. The second option is the machine be supplied with both diesel fuel and alcohol fuel. However, this procedure raises certain Problems arise because the diesel and alcohol fuels are difficult to mix and therefore not easy to use same tank can be mixed together. Should there be some water in the fuel tank for some reason are located, this promotes the separation of the fuels. Also, the alcohol tends to make the flame too extinguish, which makes starting the machine difficult. One suggestion was to use diesel fuel and the To accommodate alcohol in separate tanks, the fuels to an emulsifier and then the emulsion to Promote machine. However, it is difficult to achieve emulsification. The emulsified fuels also tend to to separate from each other over time. In particular, when the engine has been switched off, the diesel fuel and tend to the alcohol causes it to separate in the fuel line between the emulsifier and the machine. When the from each other

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If separate fuels reach the engine when starting, difficulties must be expected for the engine to ignite will. In addition, the alcohol can cause corrosion problems once it has been separated.

If the carburetor is set appropriately, a gasoline engine runs perfectly with pure alcohol with negligible Exhaust gas quantities. However, the absolute calorific value of alcohol is low compared to that of gasoline, so that it is very large Amount of alcohol must be carried if the vehicle is to have an acceptable operating range.

It is therefore an object of the present invention to provide a fuel supply system for an internal combustion engine create that reduces the fuel consumption of the machine.

Another object of the invention is to provide a fuel delivery system that can be used with a merit ignition internal combustion engine allows to burn diesel fuel and alcohol fuel at the same time without major technical changes must be made to the machine.

According to one aspect of the present invention, a method for operating an internal combustion engine is provided, which is characterized by heating a fuel to vaporize it and conveying the vaporized fuel into the air intake structure of the internal combustion engine.

According to a further aspect of the present invention is a fuel supply system for an internal combustion engine

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provided, which is characterized by heating means for vaporizing a fuel and means for conveying the evaporated fuel into the air intake structure of the internal combustion engine.

Another aspect of the invention provides an internal combustion engine system before, which is characterized by a merit ignition internal combustion engine with injection means for diesel fuel and an air intake structure for delivering combustion air to the cylinders of the engine; Heating means for vaporizing an alcohol and means for conveying the vaporized alcohol into the air inlet structure, in order to convey this together with the combustion air into the cylinders of the internal combustion engine.

It is possible to provide a control unit with both the injection means and means for Controlling the flow rate of the alcohol connected to the heating means and changing the ratio of Alcohol to diesel fuel depending on changes the machine speed is used. The control unit can also serve to control the flow of alcohol to the heating means interrupt when the machine speed falls below a predetermined minimum.

The air inlet structure may have means, such as a venturi, for creating a low pressure zone own, the heating means with the low pressure zone connected so that evaporated alcohol can enter the air intake

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construction is sucked in.

The heating means can be surfaces which are heated during operation and means for conveying the alcohol in liquid form on these surfaces. In one embodiment of the heating means, hot water is used for heating used, the above mentioned surfaces being the outsides of pipes through which the hot water is passed will. In this embodiment the heating means can be connected to the hot water outlet of the machine block. Alternatively, electrical heating means or a liquid fuel burner may be provided around the surfaces to warm up. In a further embodiment, the exhaust gases from the machine are used.

The system can include a number of safety devices. For example, a pressure sensitive Unit for interrupting the flow of alcohol to the heating means when the suction on the venturi nozzle ceases to be provided. Furthermore, means can be provided for interrupting this current when the starting circuit of the machine is switched off.

In the drawings showing an embodiment of the invention are:

Fig. 1 is a schematic representation of the fuel supply system an internal combustion engine;

Fig. 2 is a schematic representation of a fuel evaporator he having construction, and

Figures 3 and 4 are graphs.

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In Pig. 1, the box represents an internal combustion engine 10 of the compression ignition type, which has a series of diesel injectors 14 with diesel fuel from one Tank 12 is supplied. The internal combustion engine 10 is also powered by an alcohol fuel (preferably methyl alcohol, although ethyl alcohol can also be used), which is located in a tank 16. A pump 18 pumps the Fuel from the tank 16 and promotes it via a pressure regulator 20 and a solenoid shut-off valve 22 to a needle valve 24 (see also Fig. 2). The needle valve 24 conducts the fuel is metered into a fuel vaporizer 26. The vaporized fuel flows from the fuel vaporizer 26 to a venturi 28. The venturi 28 is in a conduit 30 through which air to a distribution head 32 flows, by means of which the air and the entrained fuel vapor on the cylinders of the internal combustion engine 10 will be distributed.

Reference numeral 34 denotes a control unit and reference numeral 36 denotes a control unit 34 leading to Control cable. When the internal combustion engine 10 is used to drive a vehicle, the free end of the control cable is normally connected to the accelerator pedal (not shown) of the vehicle. If, on the other hand, the internal combustion engine When part of a static structure, any arrangement for moving the control cable 36 can be used.

Control cables or rods lead from the control unit 34

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38 and 40 to the row of diesel injectors 14 and to the Needle valve 24. In the exemplary embodiment, the control unit 34 has cams (not shown) to control the control cables or rods 38 and 40 to displace a desired amount and in a desired ratio.

At 42 a membrane unit is shown. A chamber of the membrane unit 42 is connected to the Venturi nozzle 28, while a control line 44 leads to the pump 18. The control line 44 can be a mechanical connection, such as be a cable or a rod, but also an electrical connection.

The fuel vaporizer 26 and its associated Parts are shown in more detail in FIG. As can be seen from Fig. 2, the fuel evaporator 26 has a housing 46, in which two manifolds 48 are arranged. The headers 48 are connected to one another by means of a series of tubes 50. Shown at 52 is an inlet for liquid alcohol fuel and at 54 an outlet for vaporized fuel. The needle valve 24 controls the flow of alcohol fuel through the inlet 52 which is above the tubes 50 opens into the housing 46 so that fuel flowing through the inlet 52 falls onto the tubes 50. At 56 is an air inlet communicating with fuel inlet 52 and conduit 30 is shown. The reference number 58 denotes a trap for removing the unevaporated alcohol before reaching the venturi 28

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Traps 58 will also remove any water that comes out of the headers 48 or the tubes 50 could emerge, added.

The header pipes 48 are connected to the cooling system of the internal combustion engine 10 by pipes 60. Thus in the Cylinder block heated water in one of the manifolds 48, through the tubes 50 to the other manifold 48 and then to the Radiator (not shown) of the cooling system.

With that of the pipes 60 that the water to the fuel vaporizer he 26 conducts is temperature sensitive Device 62 connected, from which a control line 64 leads to pump 18. The temperature sensitive device 62 is set to operate the pump 18 and turns on when it measures a water temperature higher than the temperature of the alcohol fuel being used evaporates. The pump 18 then remains inoperative until this temperature is measured.

Another control line 66, which is part of the Starting circuit of the internal combustion engine 10 forms, as will be described, leads to the solenoid shut-off valve 22nd

Finally, a control cable or a control rod 68 leads from the control unit 34 to the pump 18 Control line is provided to keep the pump 18 out of operation when the internal combustion engine 10 is idling. The control cable or the control rod 68 is adjusted by a third cam of the control unit 34.

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If the internal combustion engine 10 is switched on in the "cold" state and cranked to start, the Diesel injection nozzles 1 4 act immediately and guide the cylinders the internal combustion engine to diesel fuel. At the same time, a signal reaches the solenoid shut-off valve via the control line 66 22 to open it.

The water coming from the machine block is relatively cold at this stage and its temperature is certainly not sufficient to actuate the temperature sensitive device 62. Polglich remains the pump 18 turned off and the Internal combustion engine 10 runs only with the supplied diesel fuel.

When the water temperature exceeds the temperature to which the temperature sensitive device 62 is set the pump 18 is turned on, so that fuel from the tank 16 through the pressure regulator 20 and the Solenoid isolation valve 22 is pumped. The pressure regulator 20 ensures that the fuel is under constant pressure the needle valve 24 is supplied. The amount of fuel measured by the needle valve 24 falls onto the tubes 50 and evaporates. It is understood that the number and arrangement of the tubes 50 are chosen so that the The possibility of liquid fuel reaching outlet 54 is minimal. The air supplied through the air inlet 56 removes vaporized fuel from the heating means formed by the fuel vaporizer 26, and the at the Venturi

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The suction prevailing at the nozzle 28 pulls the vaporized fuel into the line 30 and from there to the distribution head 32 and to the cylinders of the internal combustion engine.

When the engine is turned off, the solenoid shut-off valve 22 closes immediately and the supply the fuel vaporizer 26 with fuel is ended. It is similar when the internal combustion engine 10 fails, but remains switched on, which results in a pressure increase at the Venturi nozzle 28. This pressure increase will detected by the membrane unit 42 and the pump 18 switched off via the control line 44.

Experimental work with a diesel engine used in a medium-sized sedan has shown that the Supply of diesel fuel and alcohol fuel can be controlled approximately as shown in FIG. 3 should. From Fig. 3 it can be seen that no alcohol fuel is supplied while the engine is idling. After that, the rate of alcohol fueling should be increased fairly quickly until it is optimal Feed speed is reached. This happens at time X. After that, the speed of the alcohol fuel supply remain essentially constant. This can be done by a mechanical cam and linkage system or can be achieved by arranging an opening in front of the needle valve 24. The needle valve 24 effects a flow control, if it forms a passage, its cross-sectional area

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is smaller than that of the opening. Immediately when the needle valve 24 opens and thus has a larger cross-sectional area than the opening, the opening takes over Task of the needle valve and maintains a substantially constant flow rate even when the Speed of the internal combustion engine increased. The control unit 34 ensures by means of the control cables or Control rods 38 and 40 that the ratio of diesel fuel to alcohol is maintained in the desired degree.

Fig. 4 shows the approximate curve of the load on a test machine versus the percentage of the fed Alcohol fuel, with the remaining fuel required being diesel fuel. Although the tank 12 to that effect has been described as containing diesel fuel, it may of course be a diesel fuel substitute if so desired contain.

Figures 3 and 4 are for illustration purposes only. It goes without saying that other machines have different operating characteristics.

Instead of using hot water from the machine block to evaporate the alcohol, an electric Heating element or a liquid fuel burner can be used. For example, the burner could have a Use a small portion of the alcohol fuel present in tank 16. Alternatively, the fuel vaporizer in a heat exchange relationship with the engine block

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be arranged so that the heat directly from the machine block is routed to the fuel vaporizer. But there is also the possibility that hot exhaust gases provide the heat, required to evaporate the alcohol. For example, this can be obtained commercially and under the name "HEAT PIPE" known product can be used to conduct heat from the exhaust system to the fuel vaporizer. the Use of hot gases has the advantage that the evaporation temperatures can be reached immediately when the engine starts so that it is up to the feeding of the alcohol fuel there is no delay as is the case with the use of cooling water. Interrupting the supply of However, alcohol fuel is still required when the machine is switched off or on exposure to prevent the formation of To prevent fuel vapor in the fuel vaporizer 26.

It will be understood that an electronic control of the installation described above is easier than one mechanical control by cables etc. is feasible.

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Claims (16)

Applicant: ANGLO-TRANSVAAL CONSOLIDATED INVESTMENT COMPANY, LIMITED, Anglovaal House, 56 Main Street, Johannesburg, Transvaal Province, South Africa "Method and system for supplying fuel in internal combustion engines" Patent claims: 1 .J A method for operating an internal combustion engine, characterized by heating a fuel to this to evaporate, and conveying the evaporated fuel into the air inlet structure (30) of the internal combustion engine (10). 2. The method of claim 1, wherein the internal combustion engine (10) is a compression ignition engine, characterized in that the internal combustion engine is diesel fuel supplied by means of their injection nozzles (14) and evaporated Alcohol is carried in their air supply. 3. The method according to claim 2, characterized in that the supply of vaporized alcohol only at one Engine speed, which exceeds a predetermined minimum, occurs while the internal combustion engine (10) is at 130012/0867 Speeds below this predetermined minimum only by means of their injection nozzles (14) with diesel fuel is supplied. 4. The method according to claim 1, 2 or 3, characterized in that that the heat generated during combustion in the internal combustion engine (10) is used for evaporation purposes will. 5. Fuel supply system for internal combustion engines for Implementation of the method according to at least one of claims 1 to 4, characterized by heating means (26) for Vaporizing a fuel and means for delivering the vaporized fuel into the air intake structure (30) the internal combustion engine (10). 6. Internal combustion engine system for performing the method according to at least one of claims 1 to 4, characterized by a compression ignition internal combustion engine with injection means (14) for diesel fuel and an air intake structure (30) for conveying the combustion air to the cylinders of the engine; Heating means (26) for vaporizing an alcohol and means (54) for conveying the vaporized alcohol into the air inlet structure to to convey this together with the combustion air into the cylinders of the internal combustion engine (10). 130012/0867 ο 7. Internal combustion engine system for carrying out the method according to at least one of claims 1 to 4, characterized by an air inlet structure (30), heating means (26) for evaporation a fuel and means for delivering the vaporized fuel into the air intake structure Machine. 8. internal combustion engine system according to claim 6 or 7, characterized in that the internal combustion engine (10) has a cooling water system (60) and the heating means (26) with it are connected to the cooling water system in order to extract heat from it to evaporate the fuel. 9. internal combustion engine system according to claim 6 or 7, characterized in that the heating means (26) are connected to the exhaust system of the engine to remove the exhaust gases To withdraw heat. 10. Internal combustion engine system according to claim 6, characterized by a control unit (34) which both with the Injection means (14) as well as means (24) for controlling the flow rate of the alcohol to the heating means (26) and for changing the ratio of alcohol to diesel fuel in response to changes the machine speed is used. 11. Internal combustion engine system according to claim 10, characterized in that the control unit (34) is constructed so that it interrupts the flow of alcohol to the heating means (26), when the machine speed falls below a predetermined minimum. 130012/0867 303354? 12. Internal combustion engine system according to claim 6, 10 or 11, characterized in that the air inlet structure (30) has means (28) for creating a low pressure zone, the heating means (26) being connected to the low pressure zone so that evaporated alcohol is sucked into the air inlet structure. 13. Internal combustion engine system according to claim 6, 10 or 11, characterized in that the heating means (26) surfaces (50) which are heated during operation, and Have means (52) for conveying the alcohol in liquid form onto these surfaces. 14. Internal combustion engine system according to claim 6, 10 or 11, characterized in that the air inlet structure (30) has means (28) for creating a low pressure zone, the heating means (26) being connected to the low pressure zone so that vaporized alcohol enters the air inlet structure is sucked in, and a pressure sensitive unit (42) is connected to the low pressure zone to prevent the inflow of To interrupt alcohol to the heating means when the suction on the means for creating a low pressure zone ceases. 15. Internal combustion engine system according to claim 6, 10 or 11, characterized by a line for the alcohol stream to the heating means (26), a valve (22) in this conduit, and means (66) for connecting this valve to the starting circuit the engine so that the valve is closed when the starting circuit is taken out of service. 130012/0867 16. Internal combustion engine system according to claims 12 or 14, characterized in that the means (28) for generating a Low pressure zone in the form of a Venturi nozzle are provided. 130Ö12 / 0867