Method for determining the water content of a mixed alcohol/gasoline fuel in an internal combustion engine, and device for implementing same

1. A method for determination of the water content of a mixed alcohol/gasoline fuel in an internal combustion engine of a vehicle, comprising:

determining a first value for alcohol content of the fuel using a measurement of combustion richness;

determining a second value for alcohol content of the fuel using a measurement recorded by a sensor for measurement of the electrical conductivity of the fuel;

comparing said first value and said second value; and

upon a determination that said first value is lower than said second value, determining the water content of the fuel by assigning a predetermined value for water content associated with the pair consisting of said first value and of said second value for alcohol content.

2. The method as claimed in claim 1 , wherein the measurement of combustion richness is carried out in “hot” operation of the engine.

3. The method as claimed in claim 2 , wherein the measurement of combustion richness is carried out by means of a lambda probe positioned downstream of an exhaust manifold of the vehicle.

4. The method as claimed in claim 2 , wherein the first value for alcohol content is determined from a measurement of combustion richness carried out after introduction, into a fuel tank of the vehicle, of a new volume of fuel and after stabilization of the combustion richness measured.

5. The method as claimed in claim 2 , wherein the sensor for measurement of the electrical conductivity of the fuel is positioned at the inlet of an injection rail of the internal combustion engine or in said rail.

6. The method as claimed in claim 2 ,

wherein the first value for alcohol content is determined from a measurement of combustion richness carried out immediately before stopping the engine and is stored, and

wherein the second value for alcohol content is determined immediately after the subsequent startup of the engine.

7. The method as claimed in claim 1 , wherein the measurement of combustion richness is carried out by means of a lambda probe positioned downstream of an exhaust manifold of the vehicle.

8. The method as claimed in claim 7 , wherein the first value for alcohol content is determined from a measurement of combustion richness carried out after introduction, into a fuel tank of the vehicle, of a new volume of fuel and after stabilization of the combustion richness measured.

9. The method as claimed in claim 7 , wherein the sensor for measurement of the electrical conductivity of the fuel is positioned at the inlet of an injection rail of the internal combustion engine or in said rail.

10. The method as claimed in claim 7 ,

wherein the first value for alcohol content is determined from a measurement of combustion richness carried out immediately before stopping the engine and is stored, and

wherein the second value for alcohol content is determined immediately after the subsequent startup of the engine.

11. The method as claimed in claim 1 , wherein the first value for alcohol content is determined from a measurement of combustion richness carried out after introduction, into a fuel tank of the vehicle, of a new volume of fuel and after stabilization of the combustion richness measured.

12. The method as claimed in claim 11 , wherein the sensor for measurement of the electrical conductivity of the fuel is positioned at the inlet of an injection rail of the internal combustion engine or in said rail.

13. The method as claimed in claim 11 ,

wherein the first value for alcohol content is determined from a measurement of combustion richness carried out immediately before stopping the engine and is stored, and

wherein the second value for alcohol content is determined immediately after the subsequent startup of the engine.

14. The method as claimed in claim 1 , wherein the sensor for measurement of the electrical conductivity of the fuel is positioned at the inlet of an injection rail of the internal combustion engine or in said rail.

15. The method as claimed in claim 14 ,

wherein the first value for alcohol content is determined from a measurement of combustion richness carried out immediately before stopping the engine and is stored, and

wherein the second value for alcohol content is determined immediately after the subsequent startup of the engine.

16. The method as claimed in claim 1 ,

wherein the first value for alcohol content is determined from a measurement of combustion richness carried out immediately before stopping the engine and is stored, and

wherein the second value for alcohol content is determined immediately after the subsequent startup of the engine.

17. A device for the implementation of a method as claimed in claim 1 , comprising:

means for measurement of combustion richness,

means for determination of a first value for alcohol content of the fuel from a measurement of the combustion richness recorded by said means for measurement of combustion richness,

a sensor for measurement of the electrical conductivity of the fuel,

means for determination of a second value for alcohol content of the fuel from a measurement recorded by said sensor for measurement of the electrical conductivity of the fuel,

means for comparison of said first value and said second value, and in the event that said first value is lower than said second value, determination of the water content of the fuel by assigning a predetermined value for water content associated with the pair consisting of said first value and said second value for alcohol content.

18. The device as claimed in claim 17 , further comprising:

means for storing the first value for alcohol content determined from a measurement of combustion richness carried out immediately before stopping the engine of the vehicle.

19. A method for regulation of the operation of an internal combustion engine of a vehicle, comprising:

determining the water content of a mixed alcohol/gasoline fuel in the engine by a method as claimed in claim 1 ,

adjusting the amount of fuel injected as a function of the value of the water content thus determined.

20. The method as claimed in claim 19 , wherein said adjustment stage is carried out at the startup of the vehicle and in the “cold” operation periods of the engine.