Method for cooling a friction shift element of a transmission

Abstract

A method for cooling a friction shift element of a transmission is proposed, wherein a variable, a constant or the maximum amount of cooling oil is fed to the friction shift element in a time-controlled manner, specifically within an aftercooling phase.

Description

Claims

1-9. (canceled)

10. A method for cooling a friction shift element of a transmission, wherein one of a variable, a constant and a maximum volume of cooling oil is fed to the friction shift element within an aftercooling phase.

11. The method for cooling the friction shift element of the transmission according to claim 10, wherein a duration of a cooling and the aftercooling phases is determined as a function of at least one of: one of the variable, the constant and the maximum volume of the cooling oil;a difference in a rotational speed when the shift element is engaged;a duration of shifting;a sump temperature or a temperature of a further temperature measurement site as ascertained by one or more of a temperature sensor;a clutch torque;one of an absolute clutch input and an output rotational speeds;a current clutch stress;one of a current transmission rotational input speed, a current transmission output rotational speed and a difference in the current input and the output rotational speeds;a lubrication-cooling oil pump rotational speed;one of a number of previous starts, a number of occurrences of increased clutch stress in the aftercooling phase and within a prescribed time interval; andone of a function of gear and shifting.

12. The method for cooling the friction shift element of the transmission as claimed in claim 11, wherein one of a coupling torque, an average coupling torque and a highest coupling torque present during shifting is used.

13. The method for cooling the friction shift element of the transmission according to claim 10, wherein one or more of appropriate characteristic curves, performance characteristics, fixed values, offsets and other factors are linked by means of a computational algorithm to execute the method.

14. The method for cooling the friction shift element of the transmission according to claim 10, wherein after one of a time frame for cooling has been reached and the aftercooling phase has elapsed, the volume of cooling oil is switched back to a minimum.

15. The method for cooling the friction shift element of the transmission according to claim 10, wherein an appropriate limitation of torque is performed when the friction shift element is subjected to new stress within the time-controlled aftercooling phase to keep the friction shift element from becoming damaged.

16. The method for cooling the friction shift element of the transmission according to claim 15, wherein torque limitation is executed in a graduated manner on a basis of one or more of starts and stresses occurring consecutively.

17. The method for cooling the friction shift element of the transmission according to claim 16, wherein if one of a new start takes place and a stress is placed on the friction shift element within a time-controlled aftercooling phase, a counter is counted up, a counter value being used as a value for one of calculating a subsequent time duration of the aftercooling phase and serving a graduated torque reduction.

18. The method for cooling the friction shift element of the transmission according to claim 17, wherein the value of the counter value is selected based on a residual time of the aftercooling phase.

19. A method for cooling a friction shift element of a transmission, the method comprising the steps of: determining a cooling phase duration of time during which a volume of oil is supplied to the friction shift element;supplying the volume of oil to the friction shift element to withdraw heat during the duration of time of the cooling phase;determining an aftercooling phase duration of time during which the volume of the oil supplied to the friction shift element, over the duration of time of the cooling phase, is cooled; andallowing the volume of oil from the friction shift element to release heat over the duration of time of the aftercooling phase; the lengths of time of the cooling phase and the aftercooling phase are determined as a function of one or more of:a difference in a rotational speeds within the friction shift element at a start of shifting;a duration of time for the rotational speeds within the friction shift element at a start of the shifting to reach a target rotational speed;one of a temperature of a sump and a temperature of an additional temperature measurement site, as determined with a temperature sensor;a torque of the friction shift element;at least one of a clutch input rotational speeds and a clutch output rotational speed;a current clutch stress;at least one of a current transmission input rotational speed, a output rotational speed, and a difference in the current transmission input and output rotational speeds;a lubrication-cooling oil pump rotational speed;a numerical quantity of previous starts and occurrences of increased clutch stress during at least one of the duration of time of the aftercooling phase and within a prescribed time interval; anda function of one of a gear and shifting.

20. The method for cooling the friction shift element of the transmission according to claim 19, further comprising the step of using one of an average coupling torque and a highest coupling torque present during shifting for determining the lengths of time of the cooling phase and the aftercooling phase.

21. The method for cooling the friction shift element of the transmission according to claim 19, further comprising the step of using one or more of appropriate characteristic curves, performance characteristics, fixed values, offsets and additional factors linked by means of a computational algorithm.

22. The method for cooling the friction shift element of the transmission according to claim 19, further comprising the step of returning a flow of the volume of oil to a minimum after at least one of the lengths of time of the cooling phase and the aftercooling phase have elapsed.

23. The method for cooling the friction shift element of the transmission according to claim 19, further comprising the step of limiting torque when the friction shift element is subjected to a new stress within the duration of time of the cooling phase to prevent the friction shift element from becoming damaged.

24. The method for cooling the friction shift element of the transmission according to claim 23, further comprising the step of executing the step of limiting torque a graduated manner on a basis of one of consecutive starts and consecutive stresses.

25. The method for cooling the friction shift element of the transmission according to claim 24, further comprising the step of numerically increasing a counter value when the friction shift element is subjected to a new stress within the duration of time of the aftercooling phase and using the counter value to calculate one or more of a subsequent duration of time of the aftercooling phase and the graduated manner of limiting the torque.

26. The method for cooling the friction shift element of the transmission according to claim 25, further comprising the step of selecting the amount of the counter value can be selected based on the residual time of the aftercooling phase.