Method and device for the control and diagnosis of an exhaust gas turbocharger

1. A method for controlling an exhaust gas turbocharger, comprising:

providing a compressor for the exhaust gas turbocharger;

providing a turbine;

providing an adjusting drive to adjust a turbine geometry;

determining a performance characteristic based upon a turbine output, a mass flow through the turbine, a gas temperature upstream of the turbine and a downstream gas pressure downstream of the turbine, wherein the turbine output is based upon turbine efficiency;

determining a mass flow characteristic based upon the mass flow through the turbine, the gas temperature and the downstream gas pressure;

determining an adjuster position of the adjusting drive based upon the determined performance characteristic and the determined mass flow characteristic value via an engine map; and

determining an adjusting signal to control the adjustment drive based upon the adjuster position.

2. The method as claimed in claim 1 , wherein the performance characteristic is determined based upon the turbine output divided by the mass flow and divided by the gas temperature.

3. The method as claimed in claim 1 , wherein the mass flow characteristic is determined based upon the turbine output multiplied by square root of the gas temperature and divided by the downstream gas pressure.

4. The method as claimed in claim 1 , wherein the performance characteristic and the mass flow characteristic are the only input variables of the engine map.

5. The method as claimed in claim 1 , wherein the performance characteristic is transformed, to assign engine map points of equally transformed performance characteristics to equivalent values of the adjuster position, and wherein the adjuster position for setting a turbine geometry is determined based upon the transformed performance characteristics.

6. The method as claimed in claim 1 , wherein an upstream gas pressure upstream of the turbine is determined via a further engine map based upon the adjuster position and the mass flow characteristic.

7. The method as claimed in claim 1 , wherein the downstream gas pressure is determined based upon an ambient pressure and a dynamic pressure that depends on the mass flow through the turbine.

8. The method as claimed in claim 7 , wherein the dynamic pressure is determined based upon a model, wherein the model is based upon the mass flow through the turbine.

9. The method as claimed in claim 1 , wherein an adjusting signal is determined for adjusting a setting of a by-pass valve in a by-pass based upon the adjuster position for a variable turbine geometry.

10. A method for diagnosing an exhaust gas turbocharger, comprising:

providing a compressor for the exhaust gas turbocharger;

providing a turbine;

providing an adjusting drive to adjust a turbine geometry;

determining a performance characteristic based upon a turbine output, a mass flow through the turbine, a gas temperature upstream of the turbine and a downstream gas pressure downstream of the turbine, wherein the turbine output is based upon turbine efficiency;

determining a mass flow characteristic based upon the mass flow through the turbine, the gas temperature and the downstream gas pressure;

determining an adjuster position of the adjusting drive based upon the determined performance characteristic and the determined mass flow characteristic value via an engine map; and

diagnosing the exhaust gas turbocharger based upon the adjuster position.

11. The method as claimed in claim 10 , wherein the performance characteristic is determined based upon the turbine output divided by the mass flow through the turbine and divided by the gas temperature upstream of the turbine.

12. The method as claimed in claim 10 , wherein the mass flow characteristic is determined based upon the turbine output multiplied by square root of the gas temperature upstream of the turbine and divided by the downstream gas pressure.

13. The method as claimed in claim 10 , wherein the engine map for determining the adjuster position has a first input variable based upon the performance characteristic and a second input variable based upon the mass flow characteristic.

14. The method as claimed in claim 10 , wherein the performance characteristic is transformed, to assign engine map points of equally transformed performance characteristics to equivalent values of the adjuster position, and wherein the adjuster position for setting the turbine geometry is determined based upon the transformed performance characteristics.

15. A device for controlling an exhaust gas turbocharger, comprising:

a compressor;

a turbine;

an adjusting drive to adjust a turbine geometry;

a performance characteristic based upon a turbine output, a mass flow through the turbine, a gas temperature upstream of the turbine and a downstream gas pressure downstream of the turbine, wherein the turbine output is based upon turbine efficiency;

a mass flow characteristic based upon the mass flow through the turbine, the gas temperature upstream of the turbine and a downstream gas pressure downstream of the turbine;

an adjuster position of the adjusting drive for adjusting the turbine geometry based upon the determined characteristic and the determined mass flow characteristic value via an engine map; and

an adjusting signal for controlling the adjustment drive for adjusting the turbine geometry based upon the adjuster position for adjusting the turbine geometry.

16. The device as claimed in claim 15 , wherein the adjusting of the turbine geometry is based upon an adjustment of blades of the turbine.

17. The device as claimed in claim 15 , wherein the exhaust gas turbocharger comprises a bypass channel routed in parallel to the turbine in an exhaust gas tract.

18. The device as claimed in claim 15 , wherein the bypass channel comprises an exhaust valve.

19. The device as claimed in claim 15 , wherein the engine map is stored in a data memory of the control device.

20. The device as claimed in claim 15 , wherein the turbine is controlled based upon a pilot control.