Method for determining characteristics of an automatic transmission

摘要

A method of determining a fill current value of a converter lock-up clutch of an automatic transmission. The automatic transmission comprises a hydrodynamic converter, at which a speed ratio arises, and an output shaft. In a control sequence with the output shaft being stationary, the speed ratio is influenced by changing the control current, and the fill current value is determined from the progression of the speed ratio arising, during the control sequence, in conjunction with the progression of the control current.

主权项

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 (14) is stationary; 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).