Method and control device for a turbocharger having a variable turbine flow cross section

Abstract

An actual value of a turbine flow cross section of a turbocharger of an internal combustion engine in a motor vehicle is set for a change in the load on the internal combustion engine from a larger load value to a smaller load value. The actual value setting of the smaller load value is delayed to a setpoint value that is specified for the smaller load value under stationary conditions. A device controls the progression of the method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages and novel features of the present invention will become apparent from the following description of the invention when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view of an internal combustion engine having a turbocharger with variable turbine geometry;

FIG. 2 is a schematic view showing the variation in turbine geometry;

FIG. 3 is a graph showing progression over time of a load on the internal combustion engine during a short-term acceleration process;

FIG. 4 is a graph showing a progression over time of the turbine flow cross section after a negative load change, according to the prior art; and

FIGS. 5 (a)-(f) are graphs showing corresponding progressions over time of the turbine flow cross section after a negative load change, according to the method of the invention.

Claims

1. Method for setting an actual value of a turbine flow cross section of a turbocharger of an internal combustion engine in a motor vehicle for a change in the load on the internal combustion engine from a larger load value to a smaller load value, comprising setting an actual value of the turbine flow cross section to be set for the smaller load value in a delayed manner to a setpoint value to be specified for the smaller load value under stationary conditions.

2. Method according to claim 1, wherein the setpoint value to be specified under stationary conditions is set by specifying a progression of setpoint values that results in the setpoint value which is to be specified under stationary conditions.

3. Method according to claim 2, wherein the progression is specified as a function of operating parameters of the internal combustion engine.

4. Method according to claim 3, wherein the progression is a function of at least one of: combustion chamber fuel charge, rotational speed, exhaust gas temperature, and cumulative mass air flow rate.

5. Method according to claim 3, wherein the operating parameters are dependent on the surroundings in which the internal combustion engine is operated.

6. Method according to claim 5, wherein the operating parameters include at least one operating parameter which indicates a pressure or a temperature in the intake system of the internal combustion engine.

7. Method according to claim 2, wherein the progression has at least one intermediate value of the turbine flow cross section larger than the turbine flow cross section set for the larger load value and is smaller than the turbine flow cross section to be set for the smaller load value under stationary conditions.

8. Method according to claim 1, wherein the delayed manner has a time duration of the delay is limited to a predetermined maximum value.

9. Method according to claim 1, further comprising making a check as to whether a guide blade adjustment mechanism is jammed, and activating a breakaway function in the event of a jam.

10. Method according to claim 9, wherein the breakaway function is periodically repeated.

11. Method according to claim 9, further comprising determining a frequency of occurrence of a jamming guide blade adjustment mechanism, and activating an emergency program when the frequency exceeds a predetermined threshold value.

12. Method according to claim 11, wherein the breakaway function is periodically repeated.

13. Controller for setting an actual value of a turbine flow cross section of a turbocharger of an internal combustion engine in a motor vehicle for a change in the load on the internal combustion engine from a larger load value to a smaller load value, comprising a control device configured to set an actual value of the turbine flow cross section to be set for the smaller load value in a delayed manner to a setpoint value which the control device specifies for the smaller load value under stationary conditions.

14. Controller according to claim 13, wherein the control device is configured to control a progression of setpoint values that results in the setpoint value to be specified under stationary conditions.

15. Controller according to claim 14, wherein the progression is specified as a function of operating parameters of the internal combustion engine.

16. Controller according to claim 15, wherein the progression is a function of at least one of: combustion chamber fuel charge, rotational speed, exhaust gas temperature, and cumulative mass air flow rate.

17. Controller according to claim 14, wherein the operating parameters are dependent on the surroundings in which the internal combustion engine is operated.

18. Controller according to claim 17, wherein the operating parameters include at least one operating parameter which indicates a pressure or temperature in the intake system of the internal combustion engine.

19. Controller according to claim 14, wherein the progression has at least one intermediate value of the turbine flow cross section larger than the turbine flow cross section set for the larger load value and is smaller than the turbine flow cross section to be set for the smaller load value under stationary conditions.

20. Controller according to claim 13, further comprising making a check as to whether a guide blade adjustment mechanism is jammed, and activating a breakaway function in the event of a jam.