Patent ID: 9354140
Filing Date: 2016-05-31
CPC Classification: F16H,G01M

Claim Text:
1. A method of determining characteristic values (i_EDS_WK_F) of a frictionally engaging converter lock-up clutch (WK) of an automatic transmission ( 1 ), the automatic transmission comprises an output shaft ( 14 ), a hydrodynamic startup element ( 4 ), the converter lock-up clutch (WK) and at least one transmission shift element (A, F, E), the hydrodynamic startup element ( 4 ) comprises a turbine rotor ( 6 ) and a pump impeller ( 5 ), the pump impeller is connected, in a rotationally fixed manner, to a drive motor ( 2 ), such that the pump impeller ( 5 ) rotates at an engine speed (n_M), and the turbine rotor ( 6 ) rotates at a turbine speed (n_T), a speed ratio (ν=n_T/n_M) is defined as a ratio of the turbine speed to the engine speed, the speed ratio is changeable based on an operating state existing between the turbine speed (n_T) and the engine speed (n_M), the converter lock-up clutch (WK) is disposed between the pump impeller ( 5 ) and the turbine rotor ( 6 ), the pump impeller ( 5 ) and the turbine rotor ( 6 ) are connectable, via the converter lock-up clutch (WK), either in a rotationally fixed manner or subject to slip depending on a transfer capability of the converter lock-up clutch ( 7 ), the transfer capability of the converter lock-up clutch (WK) being changeable by controlling a gearshift device ( 18 ) with an electrical control current (i_EDS_WK), for the converter lock-up clutch (WK), a fill current value (i_EDS_WK_F) existing at which the converter lock-up clutch (WK) starting from a disengaged state transitions into a state of torque transfer subject to slip, the method comprising the steps of: initiating a control sequence, with an electronic transmission control unit, when the output shaft ( continuously increasing the electrical control current, with the electronic transmission control unit, to change the speed ratio (ν) of the turbine speed to the engine speed in the control sequence; and determining, with the electronic transmission control unit, the fill current value (i_EDS_WK_F) from a progression of the speed ratio (ν) of the turbine speed to the engine speed during the control sequence in conjunction with a progression of the electrical control current (i_EDS_WK).