A hydraulically controlled park system disengages a parking pawl in response to engagement of particular shift elements. When the vehicle is one a grade, greater force may be required to dis-engage the pawl, potentially leading to a failure to dis-engage. The controller avoids this failure by engaging an uphill gear ratio and controlling the transmission input torque to transfer load from the parking pawl to the gearing prior to engaging the shift elements that dis-engage the pawl. Following dis-engagement of the parking pawl, the transmission is in a tie-up condition in which the output shaft is held stationary by shift elements. The controller transitions from this tie-up condition to the selected gear ratio by releasing shift elements.


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    Title :

    Method for disengaging hydraulic park


    Contributors:

    Publication date :

    2020-11-10


    Type of media :

    Patent


    Type of material :

    Electronic Resource


    Language :

    English


    Classification :

    IPC:    B60W CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION , Gemeinsame Steuerung oder Regelung von Fahrzeug-Unteraggregaten verschiedenen Typs oder verschiedener Funktion / F16H Getriebe , GEARING



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