Method and device for controlling an automatic transmission adapted to a strategy for automatically restarting the engine

摘要

At the beginning of the vehicle ''stop'' phase, as the pressure regulator shuts down, its return flow (12) ceases. The hydraulic relay (8) controlling the converter and lubrication also cuts out on low pressure. Thus the whole flow delivered by the accumulator is available for first gear clutch and brake purposes. On restart, this gear is available as soon as the engine reaches drive-away speed. Normal pressures return, and the system recharges ready for the next stop-and restart cycle. The accumulator's (1) stored energy, maintained automatically by a pressure-operated, electrically driven pump (5), is delivered through a valve (2) operated by the transmission controller (6), and closed during normal running. The engine management unit is programmed to shut the engine down if the vehicle stops and remains stationary for a short preset time. Hydraulic pressure is then lost in the transmission clutches (Emb) and brakes (Freins), and these elements must be restored to readiness, on the first forward gear, before the driver initiates the restart, e.g. by depressing the accelerator, if a smooth, instant drive-away is to be achieved. The transmission's engine-driven hydraulic pump (3) is also affected. The accumulator's delivery valve (2) is therefore connected both to the transmission pressure regulator (4,VRP) and to the hydraulic distributor (7,), both these components being normally provided in a single unit.