Patent ID: 8317656
Filing Date: 2012-11-27
Classification: B60W,F16H,Y10T

Abstract:
1. A method for operating a drivetrain of a motor vehicle comprising an engine, a multi-group transmission and a clutch connected between the engine and the multi-group transmission, the multi-group transmission comprising a claw-shifted main transmission and at least one of a synchronized upstream group and a synchronized downstream group, and a gear shift from a current gear to a target gear being accomplished exclusively by actuating one of the synchronized upstream group and the synchronized downstream group and without actuating the engaged clutch and without actuating the claw-shifted main transmission, the method comprising the steps of: a) reducing engine torque and, when the engine torque has either reached or fallen below a limit value, actuating the one of the synchronized upstream group and the synchronized downstream group in a direction of disengaging the current gear to be disengaged; b) when the engine torque is approximately zero, disengaging the one of the synchronized downstream group and the synchronized upstream group, and retaining the one of the synchronized downstream group and the synchronized upstream group in a neutral position; c) bringing the engine to a target speed that is dependant on the target gear to be engaged; d) when the engine has reached the target speed to within a defined tolerance, actuating the one of the synchronized downstream group and the synchronized upstream group in a direction of engaging the target gear to be engaged; and e) increasing the engine torque once the one of the synchronized downstream group and the synchronized upstream group is engaged.