Patent ID: 7674204

Claim:
A device for operating an automatic gearbox coupled to an engine of a motor vehicle by a torque converter comprising: a latching device making it possible to interlock an output shaft of the engine and an input shaft of the automatic gearbox so as to effect a lock-up and conversely to effect a release of lock-up; an engine control unit configured to transmit to the engine an order including a torque request; and a control unit for the gearbox configured to transmit to the engine control unit an order including a torque preset, the torque request being dependent on torque requested by a driver and on the torque preset, wherein upon lock-up or release of lock-up, the control unit of the gearbox is configured to compare the torque requested by the driver with a target torque and to compare the difference between a speed of the engine and a speed of a turbine of the torque converter with a threshold and to transmit to the control unit of the engine a torque preset so that the engine torque progressively reaches the target torque and the speed of the engine progressively reaches the speed of the turbine, wherein to execute a lock-up when the speed of the turbine of the converter is greater than the speed of the engine, the control unit of the gearbox is configured to transmit to the engine control unit a torque preset greater than the torque requested by the driver of the vehicle so that the speed of the engine becomes close to the speed of the turbine of the converter.