Method and Device for Increasing the Global Compression Ratio of an Internal Combustion Engine in the Case of Varying Fuel Quality

Abstract

A method and device are provided for increasing the possible compression ratio of internal combustion engines of motor vehicles in the case of varying fuel quality in an internal combustion engine having a combustion chamber for burning the fuel. The device has an apparatus for determining the knock resistance property of the fuel, an apparatus for sensing the operating state of the internal combustion engine, a water tank, and a feeding apparatus for the water. In the method, the knock resistance property of the fuel is determined and the operating state of the internal combustion engine is sensed. A need for a feed of water to the fuel is determined therefrom.

Claims

1. A method for increasing a possible compression ratio of an internal combustion engine for a motor vehicle in a case of varying fuel quality in the internal combustion engine having a combustion chamber for burning fuel, the method comprising the steps of: determining a knock resistance of the fuel and/or the fuel quality; sensing an operating state of the internal combustion engine; determining a requirement to feed water to the fuel in accordance with the determined knock resistance and/or quality fuel and the operating state of the internal combustion engine; and feeding water to the fuel according to the determined requirement.

2. The method according to claim 1, wherein the knock resistance of the fuel is determined by a sensor which is arranged at a fuel supply system.

3. The method according to claim 1, wherein the determination of the knock resistance of the fuel is carried out in a software-based fashion using operating values of the internal combustion engine which are determined at the internal combustion engine.

4. The method according to claim 1, further comprising the step of: sensing a temperature of intake air and taking into account said temperature during the determination of the requirement to feed water the fuel.

5. The method according to claim 4, further comprising the step of: sensing a water content of intake air and taking into account said water content during the determination of the requirement to feed water to the fuel.

6. The method according to claim 1, further comprising the step of: sensing a water content of intake air and taking into account said water content during the determination of the requirement to feed water to the fuel.

7. The method according to claim 1, wherein during feeding of the fuel, the water is introduced directly into the combustion chamber or into an air supply pipe of the internal combustion engine.

8. The method according to claim 1, wherein the water is mixed with the fuel and is introduced as an emulsion directly into the combustion chamber or into an air supply pipe of the internal combustion engine.

9. The method according to claim 1, wherein the method is used to increase the possible compression ratio of the internal combustion engine in the case of varying fuel quality for an alcohol flex fuel internal combustion engine.

10. A device for increasing a possible compression ratio of an internal combustion engine of a motor vehicle in a case of varying fuel quality, the internal combustion engine having a combustion chamber for burning a fuel, the device comprising: a knock resistance determining device that determines a knock resistance of the fuel; an operating state sensing device that senses an operating state of the internal combustion engine; a water tank and an associated feed apparatus that feeds water from the water tank to the fuel; and a water feed requirement determining device that determines a requirement to feed water to the fuel in accordance with the determined knock resistance of the fuel and the sensed operating state of the internal combustion engine, wherein the feed apparatus feeds water to the fuel based on the determined requirement.

11. The device according to claim 10, wherein the feed apparatus is configured to form an emulsion of fuel and water according to the determined requirement.

12. The device according to claim 10, wherein the feed apparatus for the water has an injection nozzle arranged in the combustion chamber or in an air supply pipe.

13. The device according to claim 10, wherein the internal combustion engine is an alcohol flex fuel engine.

14. A control apparatus of a motor vehicle that controls an increase of a possible compression ratio of an internal combustion engine in a case of varying fuel quality in the internal combustion engine, wherein the control apparatus is operatively configured to: read in data which permit a knock resistance of the fuel to be determined; read in data which characterize an operating state of the internal combustion engine; evaluate the read-in data in order to determine a requirement to feed water to the fuel in accordance with the determined knock resistance of the fuel and the determined operating state of the internal combustion engine; and control metering and feeding of water to the fuel based on the determined requirement to feed the water to the fuel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] FIG. 1 is a schematic illustration of an exemplary device according to the invention for increasing the possible compression ratio of internal combustion engines of motor vehicles in the case of varying fuel quality in an internal combustion engine.

[0050] FIG. 2 is a schematic illustration of a further exemplary device according to the invention, wherein the water is fed directly into the combustion chamber.

[0051] FIG. 3 is a schematic illustration of a further exemplary device according to the invention, wherein an emulsion of water and fuel is fed to the combustion chamber.

DETAILED DESCRIPTION OF THE DRAWINGS

[0052] FIG. 1 shows an exemplary device 1 for increasing the possible compression ratio of internal combustion engines of motor vehicles in the case of varying fuel quality in an internal combustion engine 10 of a motor vehicle. FIG. 1 illustrates a cylinder 11, illustrated by way of example, of the internal combustion engine 10 with a piston 13 which can move up and down in the combustion chamber 12, in order to burn the fuel. The device 1 has a fuel tank 20 with a fuel sensor 21, and a knock sensor 22 which is arranged on the cylinder 11 and has the purpose of determining the knock resistance of the fuel. The internal combustion engine 10 can be, for example, an alcohol flex fuel engine, and in such an embodiment the fuel tank 20 contains a mixture of gasoline and alcohol fuel.

[0053] In addition, the device 1 has a rotation speed sensor 23 on the crankshaft 15 of the internal combustion engine 10, connected to the computing device 40, which rotation speed sensor 23 has the purpose of sensing the operating state of the internal combustion engine 10. A temperature sensor 24 and a water content sensor for sensing the temperature and the water content of the air which is conducted into the combustion chamber 12 are also arranged on the air supply pipe 14 of the exemplary embodiment. Connections for transferring measurement signals or control signals are illustrated in the form of dashed lines.

[0054] In addition, provided on the device 1 are a water tank 30 and a water line 31 as a feed device for feeding water to the fuel, and an injection nozzle 32 for injecting water into the air feed line 14. Provided on the internal combustion engine 10 are a fuel tank 20, a fuel line 25 and an injection nozzle 26 as a feed device for the fuel, which injection nozzle 26 has the purpose of injecting fuel into the combustion chamber 12. The device 1 also has an apparatus 50 for determining a requirement to feed water to the fuel in accordance with the determined knock resistance of the fuel and the operating state of the internal combustion engine 10.

[0055] FIG. 2 shows an further exemplary device 1 for increasing the possible compression ratio of internal combustion engines 10 of motor vehicles in the case of varying fuel quantity of a motor vehicle. FIG. 2 differs from FIG. 1 in that the injection nozzle 32 for the water is arranged on the wall of the combustion chamber, so that the water is fed to the fuel directly in the combustion chamber.

[0056] FIG. 3 shows an further exemplary device 1 for increasing the possible compression ratio of internal combustion engines 10 of motor vehicles in the case of varying fuel quality of a motor vehicle.

[0057] FIG. 3 differs from FIG. 2 in that it has a mixing apparatus 27 for adding water to the fuel, which mixing apparatus 27 is suitable for forming an emulsion of fuel and water. The mixing apparatus 27 forms part of the feed apparatus for the water and is connected to the fuel tank 20 via the fuel line 25 and to the water tank 30 via the water line 31 and is configured to form an emulsion of water and fuel. In addition, the mixing apparatus 27 is connected via an emulsion line 28 to the injection nozzle 29 which serves to inject the emulsion into the combustion chamber 12 of the internal combustion engine 10.

LIST OF REFERENCE NUMBERS

[0058] 1 Device for increasing the compression capability of a fuel [0059] 10 Internal combustion engine [0060] 11 Cylinder [0061] 12 Combustion chamber [0062] 13 Piston [0063] 14 Air feed line [0064] 15 Crankshaft [0065] 20 Fuel tank [0066] 21 Fuel sensor [0067] 22 Knock sensor [0068] 23 Rotational speed sensor [0069] 24 Temperature sensor [0070] 25 Fuel line [0071] 26 Injection nozzle [0072] 27 Mixing apparatus [0073] 28 Emulsion line [0074] 29 Injection nozzle [0075] 30 Water tank [0076] 31 Water line [0077] 32 Injection nozzle [0078] 34 Water content sensor [0079] 40 Computing apparatus [0080] 50 Apparatus for determining a requirement to feed water to the fuel

[0081] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.