Method for controlling an internal combustion engine using valve lift switchover

1. A method for controlling an internal combustion engine using a valve lift switchover, comprising:

determining a cylinder charge via a basic intake manifold model for at least one first and one second valve lift of the internal combustion engine starting from a recorded intake manifold pressure;

detecting a switchover-relevant pressure range for the valve lift switchover on the basis of the recorded intake manifold pressure; and

determining a switchover cylinder charge corresponding to an operating point of the internal combustion engine for the switchover-relevant pressure range via a switchover intake manifold model, such that the valve lift switchover activated on the basis of the switchover cylinder charge is executed with constant torque of the internal combustion engine.

2. The method as claimed in claim 1 , wherein the cylinder charge is a basic air quantity.

3. The method as claimed in claim 2 , wherein the basic intake manifold model determines the basic cylinder charge for each valve lift based in each case on a separate basic characteristic map.

4. The method as claimed in claim 2 , wherein the switchover intake manifold model is composed of the basic intake manifold model for each valve lift and a charge correction model for each valve lift.

5. The method as claimed in claim 4 , wherein the basic intake manifold model determines the basic cylinder charge for each valve lift based in each case on a separate basic characteristic map.

6. The method as claimed in claim 5 , wherein the charge correction model determines a correction value for the basic cylinder charge for each valve lift, the correction value added to the basic cylinder charge yields a correction cylinder charge.

7. The method as claimed in claim 6 , wherein the correction value is a correction air quantity.

8. The method as claimed in claim 7 , wherein the correction model has in each case a charge correction characteristic map per valve lift.

9. The method as claimed in claim 8 , further comprises covering the switchover-relevant pressure range with the charge correction characteristic map.

10. The method as claimed in claim 9 , further comprises correcting operating data of the engine for the purpose of torque correction of the latter, taking into account the correction cylinder charge and specific correction variables determined on this basis, an ignition angle correction and a correction of a throttle valve position.

11. The method as claimed in claim 10 , wherein the specific correction variables include an injection time correction.

12. The method as claimed in claim 9 , further comprises determining the correction cylinder charge in a weighted manner, wherein the correction value is incorporated into the correction cylinder charge in decreasing proportion as the distance from a switchover pressure increases.

13. The method as claimed in claim 2 , wherein the switchover intake manifold model is formed solely by a detailed intake manifold model for each valve lift limited to the switchover-relevant pressure range.

14. The method as claimed in claim 13 , wherein the detailed intake manifold model calculates the switchover cylinder charge for the respective valve lift specifically or determines the charge based on a charge characteristic map specific to each valve lift.

15. The method as claimed in claim 13 , wherein the detailed intake manifold model is implemented with greater precision than the basic intake manifold model in respect of the determination of the cylinder charge in order to save computing power or memory storage capacity.

16. The method as claimed in claim 13 , wherein the detailed intake manifold model is implemented with greater precision than the basic intake manifold model in respect of the determination of the cylinder charge in order to save computing power and memory storage capacity.