Method for checking the actuating accuracy of a clutch when an electric or hybrid motor vehicle is at a standstill

A method for checking the positioning accuracy of a clutch (7, 8) when an electric or hybrid motor vehicle is at a standstill, wherein the electric or hybrid motor vehicle has at least one electric machine (2) and wherein the clutch (7, 8) to be checked is arranged in a force flow between the electric machine (2) and a shaft (5, 6) which can be held stationary, comprising at least the followings steps:

• holding the shaft stationary
• setting a defined setpoint torque at the clutch (7, 8) to be checked,
• steadily accelerating the electric machine (2) up to the first slip of the clutch (7, 8),
• comparing the torque reached by the electric machine (2) with the setpoint torque preset at the clutch (7, 8);
• wherein the clutch (7, 8) is part of a clutch system having at least two clutches (7, 8), wherein each clutch (7, 8) of the clutch system is checked in terms of its positioning accuracy, wherein, during the checking of one clutch (7, 8) of the clutch system, the at least one other clutch (7, 8) is fully disengaged;
• and
• wherein the service brake is locked automatically without intervention by the driver.

A method for checking the positioning accuracy of a clutch (7, 8) when an electric or hybrid motor vehicle is at a standstill, wherein the electric or hybrid motor vehicle has at least one electric machine (2) and wherein the clutch (7, 8) to be checked is arranged in a force flow between the electric machine (2) and a shaft (5, 6) which can be held stationary, comprising at least the followings steps:

• holding the shaft (5, 6) stationary,
• accelerating the electric machine (2) to a defined speed,
• setting a defined setpoint torque at the clutch (7, 8) to be checked, and
• comparing the torque of the electric machine (2) which is needed to maintain a constant speed with the setpoint torque set at the clutch (7, 8), wherein the comparing step includes determining a torque difference between the torque reached and the setpoint torque;
• and
• automatically identifying an altered friction coefficient in the clutch based on the torque difference.

A method for checking the positioning accuracy of a clutch (7, 8) when an electric or hybrid motor vehicle is at a standstill, wherein the electric or hybrid motor vehicle has at least one electric machine (2) and wherein the clutch (7, 8) to be checked is arranged in a force flow between the electric machine (2) and a shaft (5, 6) which can be held stationary, comprising at least the followings steps:

• holding the shaft (5, 6) stationary,
• setting a defined setpoint torque at the clutch (7, 8) to be checked,
• accelerating the electric machine (2) to a threshold measurement level, and comparing a needed torque of the electric machine (2) which is needed to satisfy the threshold measurement level with the setpoint torque set at the clutch (7, 8) and determining a torque difference therebetween;
• and
• identifying an altered friction coefficient based on the torque difference and correcting for the altered friction coefficient.