Method and control unit for damping load impacts with an open torque converter lockup clutch
A method controls an internal combustion engine in a drive train having a hydraulic torque converter with a pump wheel and a turbine wheel, during a changeover from an overrun mode into a traction mode. In the method, the rotational speeds of the pump wheel and of the turbine wheel are sensed simultaneously and compared with one another, and a deviation of the rotational speed of the pump wheel from the rotational speed of the turbine wheel being determined. If the rotational speed of the turbine wheel is higher than the rotational speed of the pump wheel and the deviation drops below a predefined threshold value, the torque of the internal combustion engine is set in dependence on the deviation and a rate of change of the rotational speed of the pump wheel. Furthermore a control unit is configured to carry out such a method.
1. A method for controlling an internal combustion engine in a drive train during a changeover from an overrun mode into a traction mode, the drive train having a hydraulic torque converter with a pump wheel and a turbine wheel, which comprises the step of:
sensing simultaneously rotational speeds of the pump wheel and of the turbine wheel;
comparing the rotational speeds of the pump wheel and the turbine wheel with one another;
determining a deviation of the rotational speed of the pump wheel from the rotational speed of the turbine wheel; and
if the rotational speed of the turbine wheel is higher than the rotational speed of the pump wheel and the deviation drops below a predefined threshold value, setting a torque of the internal combustion engine in dependence on the deviation and a rate of change of the rotational speed of the pump wheel if a driving stability program has not been deactivated.
2. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine in dependence on the deviation and the rate of change only if a change in a transmission ratio which is set in a change speed gearbox is not implemented.
3. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine in dependence on the deviation and the rate of change if a modification of a control of the internal combustion engine for accelerated heating of catalytic converter is not activated.
4. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine in dependence on the deviation and the rate of change only if a torque converter lockup clutch is not closed.
5. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine additionally in dependence on a transmission ratio which is set in a change speed gearbox.
6. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine additionally in dependence on a request of a driver.
7. The method according to claim 1 , which further comprises setting the torque of the internal combustion engine in dependence on the deviation and the rate of change until the deviation exceeds the predefined threshold value after a change of a sign of the deviation.
8. A control unit for controlling an internal combustion engine in a drive train during a changeover from an overrun mode into a traction mode, the drive train having a hydraulic torque converter with a pump wheel and a turbine wheel, the control unit comprising:
a controller programmed to:
simultaneously sense rotational speeds of the pump wheel and of the turbine wheel;
compare the rotational speeds of the pump wheel and of the turbine wheel with one another;
determine a deviation of the rotational speed of the pump wheel from the rotational speed of the turbine wheel;
set a torque of the internal combustion engine in dependence on the deviation and of a rate of change of the rotational speed of the pump wheel if the rotational speed of the turbine wheel is higher than the rotational speed of the pump wheel and the deviation drops below a predefined threshold value; and
set the torque of the internal combustion engine in dependence on the deviation and the rate of change if a modification of a control of the internal combustion engine for accelerated heating of a catalytic converter is not activated.
9. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine in dependence on the deviation and the rate of change if a driving stability program has not been deactivated.
10. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine in dependence on the deviation and the rate of change only if a change in a transmission ratio which is set in a change speed gearbox is not implemented.
11. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine in dependence on the deviation and the rate of change only if a torque converter lockup clutch is not closed.
12. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine additionally in dependence on a transmission ratio which is set in a change speed gearbox.
13. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine additionally in dependence on a request of a driver.
14. The control unit according to claim 8 , wherein said controller is further programmed to set the torque of the internal combustion engine in dependence on the deviation and the rate of change until the deviation exceeds the predefined threshold value after a change of a sign of said deviation.