Patent ID: 7574295

Claim:
Method for controlling automatic or automated transmission downshift used for power braking of a vehicle and comprising a group of at least two standard downshift laws (C (n)(n−1) , C (n+1)(n) ) between a gear n+1 and a gear n, and between a gear n and a gear n−1, respectively, as a function of the speed at the wheel (V) and acceleration pedal depression (E), comprising, when the driver begins to brake when the vehicle is in gear n+1: defining, below a certain arbitrary threshold (E threshold ) of depression of the acceleration pedal, a group of new downshift laws intended to replace the standard downshift laws, each new downshift law being shifted by a gap (Δ (n)(n−1) , Δ (n+1)(n) ) with respect to the respective standard downshift law, this gap (Δ (n)(n−1) , Δ (n+1)(n) ) being calculated between the arbitrary threshold (E threshold ) of depression of the acceleration pedal and the depression zero of the acceleration pedal, and downshifting the transmission by at least one transmission ratio if the calculated gaps (Δ (n)(n−1) , Δ (n+1)(n) ) are such that the operating point of the vehicle defined by the speed at the wheel (V) and the acceleration pedal depression (E) when the driver begins to brake becomes lower than at least one (C (n+1)(n) +Δ (n+1)(n) ) of the new downshift laws, wherein the transmission is downshifted directly by more than one transmission ratios if the calculated gaps (Δ (n)(n−1) , Δ (n+1)(n) ) are such that the operating point of the vehicle (V,E) when the driver begins to brake becomes lower than more than one of the new downshift laws.