Hydraulic clutch and method for determining an adaptive clutch fill volume of the hydraulic clutch

A method for learning a characteristic return spring pressure of a hydraulic clutch, the method comprising:

• applying a first pressure pulse to the hydraulic clutch when the hydraulic clutch is in a disengaged state;
• applying a second pressure pulse to the hydraulic clutch when the hydraulic clutch is in the disengaged state, a pressure level of the second pressure pulse smaller than the pressure level of the first pressure pulse;
• applying a third pressure pulse to the hydraulic clutch when the hydraulic clutch is in the disengaged state, the pressure level of the third pressure pulse smaller than the pressure level of the first pressure pulse and greater than the pressure level of the second pressure pulse;
• determining an inflection event at a torque path that comprises the hydraulic clutch while applying the third pressure pulse;
• deriving the characteristic return spring pressure of the hydraulic clutch from the inflection event.

A method for engaging a hydraulic clutch comprising:

• reading in a characteristic clutch volume of the hydraulic clutch from a memory;
• reading in a characteristic return spring pressure of the hydraulic clutch from the memory;
• deriving a filling pressure from the characteristic clutch volume, a pulse length and a return spring pressure;
• deriving a command pressure from the filling pressure;
• and
• applying the command pressure to a servo valve of the hydraulic clutch for engaging the hydraulic clutch.

A hydraulic clutch assembly, comprising:

• a hydraulic clutch;
• a filling pipeline connected to the hydraulic clutch;
• a clutch fill regulator valve in the filling pipeline and dividing the filling pipeline into an upstream pipeline configured to receive a hydraulic fluid with a line pressure and into a downstream pipeline configured to connect the clutch fill regulator valve to the hydraulic clutch;
• and
• a control unit, comprising:
• an output port configured to provide an output control signal to the clutch fill regulator valve of the hydraulic clutch, and
• an input port configured to receive an input signal from an inflection event sensor in a torque path that comprises the hydraulic clutch;
• and
• a processor configured to determine a characteristic clutch value from the output control signal and from the input signal and configured to store the characteristic clutch value.