AU6425294A

AU6425294A - Process and device for operating an internal combustion engine or a combustion plant

Info

Publication number: AU6425294A
Application number: AU64252/94A
Authority: AU
Inventors: Manfred Wust
Original assignee: INTERTECHNOLOGY HOLDING Ltd
Current assignee: INTERTECHNOLOGY HOLDING Ltd
Priority date: 1993-03-26
Filing date: 1994-03-08
Publication date: 1994-10-24
Also published as: DE4309833C2; FI945512A0; KR970004672B1; EP0642627A1; TW265389B; PL306416A1; FI945512A; WO1994023194A1; IL109091A0; CZ291394A3; BR9404761A; DE4309833A1; JPH07508332A; CN1129028A; JP2598622B2; CA2136613A1

Description

METHOD AND APPARATUS FOR OPERATING AN INTERNAL COMBUSTION ENGINE OR A FURNACE The invention relates first of all to a method for operating an internal combustion engine or a furnace, wherein liquid fuel is heated before it is introduced into the combustion space. Moreover, the invention also relates to an apparatus of the introductory portion of claim 9. During the operation of internal combustion engines, the preheating of the fuel before it is brought into the combustion chamber, in order to affect particularly the fuel consumption and also the emission of pollutants in a favourable manner by expanding the gasoline or fuel during the heating, is well known. The German publication 32 03 764 discloses an apparatus for supplying liquid or gaseous gasoline or fuels to internal combustion engines such as reciprocating internal combustion engines operating on the spark-ignition or automatic ignition principle, or also to stationary combustion installations, in which a preheater is integrated in the gasoline or fuel supply line. The preheater is designed and controlled in such a manner here, that the fuel is brought to a particular temperature. The emission of pollutants is affected advantageously to only a slight degree by these means. It is therefore an object of the present invention to provide a method and an apparatus of the initially described type, with which the emission of pollutants can be reduced significantly during the operation of an internal combustion engine or also of furnaces. To accomplish this objective, the method of the above-named type is characterized by the distinguishing features given in the characterizing part of claim 1. Important further developments of the inventive method are given in claims 2 to 10. An apparatus for carrying out the method is given in claim 11. Significant refinements of this apparatus are given in claims 10 to 23. For the inventive method and apparatus, the fuel is heated and prepared in four steps in the preheater. Depending on the nature of the fuel used to operate the internal combustion engine or the furnace, the fuel is first of all brought to a base temperature between 400 and 60'C (depending on the fuel) in the preheating step, in order to have the same parameters continuously, whether it be summer or winter, for the subsequent warming or heating step. In the second preheating or warming step that follows, which is an expansion step, the fuel is expanded by heating to a temperature between 50* and 150*C (fuel specific) at constant energy density, in order to be transferred then into an innermolecularly unstable state in the subsequent third step (reaction step) with further heating to temperatures between 80* and 200*C (again fuel-specific). In this innermolecularly unstable state, the fuel is then heated further in the fourth and last step, the vaporisation - 1 step, with an increase in pressure up to a temperature, just below that at which the gasoline or fuel evaporates or outgasses (vaporisation temperature), so that, after it is brought into the combustion space and mixed with air through a carburetor, an injection nozzle or the like, there exists a fuel-air mixture, which makes possible an immediate, approximately residue-free combustion with a maximum release of energy and a minimum emission of pollutants, for example, directly at top dead center of a reciprocating piston internal combustion engine. The fuel is to be introduced in this state directly at the vaporisation or vapor transition point as a fine, easily inflammable (liquid) spray mist, This offers significant advantages, especially also in the case of spontaneously igniting internal combustion engines. Also in the case of spark-ignited internal combustion engines, the fuel mixture introduced should be ignited in the shortest possible time. In the individual preheating and heating steps, the temperature to be reached can be controlled exactly by means of control electronics. Likewise, the input and output data, such as throughput and pressure before the preheater should be determined, in order to control the fuel-specific operating parameters with a view to reaching the innermolecularly unstable state shortly before the vapor transition or vaporisation point precisely in the preheater. Due to the overall attainable expansion of the fuel, the easy and rapid ignitability and the changes in the state of the material in the combustion space, together with the thereby released energy and the therefrom resulting high energy density, outstanding results are achievable with respect to performance and approximately residueless combustion. An aftertreatment of the exhaust gas generally is not required. Conventional internal combustion engines can also be retrofitted with the apparatus. Such retrofitting is associated with appreciable reductions in fuel consumption and decreases to a minimum in the pollutants emitted. Fuel savings between 50 and 80% have been confirmed by experiments with conventional car engines. Likewise, an increase in power by 17 to 23% was observed. The fuel-air mixture, brought into the combustion space, must also be prepared for the ignition by means of simple control electronics and the ignition equipment, on the one hand, as provided for in an advantageous refinement of the invention, by first of all polarizing the mixture by applying a negative voltage of 120 V (from the cathode of the spark plug to the cylinder walls (electrode)). After that, the region between the electrode and the cathode of the spark plug can be ionized by applying a negative voltage of 320 V so that an ionised field (cloud) can be generated about the cathode and the electrode of the spark plug. By applying a negative spike pulse voltage of the order of 3000 V to 5000 V the ignition spark ignites the cloud, which is then transformed into a plasma state, exceptionally high temperatures of up to 20000*C resulting. With that, the fuel mixture as a whole can be ignited quickly and reliably. In order to take into account the further heating of fuel, brought to the vaporisation temperature, in a fuel distributor in the fuel not required at the moment for the -2operation of the internal combustion engine before it is reintroduced into the preheater, a particularly preferred development of the inventive method or of the inventive apparatus provides two independent fuel cycles with an interposed compensation step. For this, the preheater and the fuel distributor are advisably contained in a first fuel cycle. The second fuel cycle is connected to the fuel tank. If the amount of fuel, not required to operate the internal combustion engine, is returned to the first fuel cycle (recycled), the fuel can be mixed in the compensating tank or the compensation step with the fuel from the fuel tank, which has not been preheated, in order to compensate for any previous outgassing processes and regain the desired temperature level. Any excess amounts of fuel can be returned to the fuel tank over a recycling line in the second fuel cycle. The amount of fuel to be admixed can be controlled by the control electronics as a function of the operating parameters. In addition, an electronically controlled 3 way mixer can be present in the compensating tank. For a further explanation of the invention, reference is made to the drawing and the subsequent description. In the drawing Figure 1 shows a flow and control diagram of the inventive method and the inventive apparatus and Figure 2 shows a further inventive flow diagram with an additional compensation step. In the drawing, the apparatus for carrying out the inventive method is generally labelled 1. In the embodiment illustrated, it is constructed as equipment, which can also generally be mounted on existing internal combustion engines or furnaces with, for example, a housing of an impact-resistant plastic or metal. All components are to be thermally insulated, so that the current consumption as a whole remains small and no heat penetrates to parts, which do not have to be heated. The control electronics can be constructed and mounted as a hybrid in a contact strip in the interior of the housing. The external connecting pieces for the fuel are of standard construction and can thus also be adapted to existing vehicles with gasoline or diesel engines. The housing can, moreover, be equipped with vibration-damping mountings, by means of which it is mounted on the vehicle. The tank for the liquid fuel, such as super or diesel fuel, is labelled 2. A fuel line 3 leads from the tank 2 to a fuel pump 4, to which are connected in series a check valve 5, a flow sensor 6 and a pressure sensor 7. The flow sensor 6 and the pressure sensor 7 are connected over leads 8 and 9 with the control electronics, which are generally labelled 10 and can take into consideration fuel-specific flow and pressure values. The voltage is supplied by a generator 11, on which likewise a sensor 12 is mounted to monitor the running. The sensor 12, in turn, is connected with the control electronics 10. A vehicle electrical system blade 13 is connected with network preparation system 14 that is provided at the control electronics 10. -3- The preheater, as a whole, is labelled 15. This preheater 15 is constructed as a thermal coaxial heater coil and preferably has 12 coils in a length of 36 cm per coil and consists of a copper pipe with a minimum internal diameter of 8 mm. The heater coil is enveloped by an insulation 16. Overall, the heater coil is constructed in 4 stages, in which in each case four heating elements/thermal sensor elements 17, 18. 19 and 20 are provided. Each of the heating elements can be controlled by the control electronics 10. The temperature of the fuel passing through can be adjusted precisely in the respective stages to 1/10*C as a function of the nominal/actual value comparison. At the outlet of the coil 15, a thermosensor 21 is provided, which reports the outlet temperature to the control electronics. The fuel is supplied over a thermo-pressure pipeline 22 to a fuel distributor 23, such as a carburetor, an injector pump or a distributor, from where the fuel or the fuel/air mixture reaches the combustion space of the internal combustion engine or of a furnace. In the embodiment shown in Figure 2, identical parts have been provided with the identical reference numbers. A closer representation of the details of the preheater 15 have been omitted here for the sake of greater clarity. Two separate fuel cycles I and II, which can be connected together over a compensating tank 24, are provided for this embodiment. The first fuel cycle I has the preheater 15, as well as the fuel distributor 23. In addition, a working pump 25 is provided. A pressure-measuring site is disposed at 26. Moreover, a bulk storage facility 27 is present. The fuel, not supplied to the combustion space, can be supplied by the fuel distributor 23 over the recycling part 1.1 of the first fuel cycle I to the compensating tank 24. The pressure line 3 of the second fuel cycle II is also connected to the compensating tank 24. Before the entrance to the compensating tank, a mixer 28 is also connected to this pressure line so that an amount of fuel can, electronically controlled, be recycled over the bypass line 11.22 into the recycling line 11.3 to the fuel tank 2 instead of entering the compensating tank. If the fuel, which has been heated approximately to the engine temperature in the fuel distributor 23 and is not required, reaches the recycling line 1.1 (expanded), during which process outgassing may occur, non-preheated fuel is admixed in the compensating tank 24. An electronically controllable 3-way mixer, which is not visible, is disposed in the compensating tank 24. Fuel is admixed by way of the 3-way mixer in an amount and for the time required for achieving the desired parameters (temperature) in the fuel. Any excess fuel is then returned over recycling line 11.3 back into the fuel tank 2. -4-

Claims

1. A method for operating an internal combustion engine or a furnace, wherein liquid fuel is heated before it is introduced into the combustion space, characterized in that the fuel, before it is introduced into the combustion space, is brought in an innermolecularly unstable state to about the vaporisation temperature by the following preheating and heating steps: a) the fuel is heated in a preheating step to a base temperature between 40* and 60*C; b) the fuel is expanded in an expansion step by being heated to a temperature between 500 and 150*C at a constant energy density; c) the fuel is converted in a subsequent reaction step by being heated to a temperature between 80* and 200*C into an innermolecularly unstable state; d) the fuel is heated in a vaporisation step with increase in pressure to a value between 2.5 and 40 bar up to the vaporisation temperature.

2. The method of claim 1, characterized in that the temperature of the fuel in each preheating and heating step is determined separately and controlled as a function of a nominal/actual value comparison.

3. The method of one of the claims 1 to 2, characterized in that the fuel, supplied at the vaporisation temperature under pressure, is mixed with compressed air and the fuel/air mixture is ignited by means of an igniter with negative ignition pulses.

4 The method of claim 3, characterized in that the ignition is prepared by polarizing the fuel/air mixture by applying a negative voltage to an igniter.

5. The method of claim 4, characterized in that the polarization is brought about by applying a negative voltage of 120 V.

6. The method of one of the claims 3 to 5, characterized in that the spatial region of the combustion space between the electrode and the cathode of the spark plug is ionized by the application of a negative voltage.

7. The method of claim 6, characterized in that the ionization of the region between the electrode and the cathode of the igniter is accomplished by the application of a negative voltage of about 320 V.

8. The method of one of the claims 4 to 7, characterized in that the ignition spark of the igniter is generated by a negative spike pulse voltage of the order of 3000 V to 5000 V. -5-

9. The method of one of the claims 1 to 8, characterized in that the preheated fuel, not brought in the combustion space, is mixed in a compensating step with fresh non-preheated fuel.

10. The method of claim 9, characterized in that, by admixing non heated fuel, the fuel can be cooled back to a specifiable temperature below the vaporisation temperature in the compensating step and any excess fuel can be discharged from the compensation step.

11. An apparatus for operating an internal combustion engine or a furnace with an igniter, as well as with a combustion space, which has an inlet duct and an outlet duct and can be acted upon over a fuel-supply system, comprising a fuel tank (2) as well as a fuel-supply line (3), with a liquid fuel and/or a fuel air mixture, the fuel-supply system having a preheater (15) for the fuel that is to be supplied, especially for carrying out the method of one of the claims 1 to 10, characterized in that the preheater (15) is constructed in four steps with heating elements (17, 18, 19, 20) and temperature sensors assigned to each step and that the fuel, flowing from the preheater (15), can be supplied over a thermal pressure line (22) to the combustion space.

12. The apparatus of claim 11, with a fuel distributor (23) for the fuel that is to be supplied, characterized in that the preheater (15) is disposed ahead of the fuel distributor (23).

13. The apparatus of claims 11 or 12, characterized in that the heating elements (17, 18, 19, 20) can be controlled separately at each step by means of control electronics (10) as a function of a nominal value/actual value comparison.

14. The apparatus of one of the claims 11 to 13, characterized in that the preheater is constructed as a heater coil.

15. The apparatus of claim 13, characterized in that the heater coil is constructed from copper pipes with a minimum internal diameter of 8 mm.

16. The apparatus of claims 13 or 14, characterized in that the heater coil has twelve coils.

17. The apparatus of claim 16, characterized in that the heater coil is 36 cm long per coil.

18. The apparatus of one of the claims 11 to 17, characterised in that flow sensors (6) and pressure sensors (7), as well as an adjustable check valve (5), which can be connected with control electronics (10) are disposed ahead of the preheater (15).

19. The apparatus of one of the claims 11 to 18, characterized in that a negative -6- pressure switch, which can be connected with the control electronics (10), is disposed after the preheater (15).

20. The apparatus of one of the claims 11 to 19, characterized in that the preheater (15) and the fuel distributor (23) are connected to a first fuel cycle (I) and the fuel tank (2) is connected to a second fuel cycle (II), the first and the second fuel cycles (I, II) being connectable over a compensating tank (24).

21. The apparatus of claim 19, characterized in that the compensating tank (24) is disposed in the flow direction of the fuel after the fuel distributor (23) in the first fuel cycle (I).

22. The apparatus of claims 20 or 21, characterized in that fuel can be returned from the compensating tank (24) to the fuel tank.

23. The apparatus of claim 22, characterized in that the compensating tank (24) has an electronically controllable 3-way mixer. -7-