Automatic gear change control method for a motor vehicle automatic discrete step gearbox

A method for controlling a gear change in an automatic discrete step gearbox of a motor vehicle, having a first engageable and disengageable frictional connection associated with an old gear and having a second engageable and disengageable frictional connection associated with a new gear between associated gearbox elements and having a controller for working pressures for actuating the first and second frictional connections participating in the gear change, comprising the steps of providing a rotational speed adaptation phase within a gear-changing period;

• measuring the rotational speed adaptation phase from appearance of a gear-changing signal which initiates a beginning of control of the working pressures to attainment of a rotational speed value of a gearbox input rotational speed associated with the new gear;
• in the rotational speed adaptation phase one of reducing to zero and controlling to a low constant value near zero a transmission torque of one frictional connection;
• controlling a transmission torque, which determines a variation of the gearbox input rotational speed, of the other frictional connection to an adaptation value;
• controlling, at a beginning of the rotational speed adaptation phase, the transmission torque determining the variation of the gearbox input rotational speed to a current value of torque of the gearbox input shaft with the gearbox input rotational speed having the value associated with the old gear;
• and ending the rotational speed adaptation phase at a time at which the gearbox input rotational speed has reached a value associated with the new gear,
• wherein in the rotational speed adaptation phase a delay regulation is superimposed on control of the transmission torque determining the variation of the gearbox input rotational speed such that a required value for the control of the transmission torque is determined by a correction value which is formed from the deviation of the actual value of the gearbox input rotational speed by a required deceleration value of the gearbox input rotational speed,
• and the required value of the transmission torque is formed from a deceleration torque, from the gearbox input torque and from the transmission torque under the conditions such that
• (1) p.sub.-- K.sub.-- soll*C.sub.-- Kzu=M.sub.-- Kzu for change-up operations,
• (2) p.sub.-- K.sub.-- soll*C.sub.-- Kab=M.sub.-- Kab for release gear changes,
• (3) the transmission torque determining the variation of the gearbox input rotational speed
• =M.sub.-- Kzu=M.sub.-- Mot*.mu.+M.sub.-- J for change-up operations, and
• =M.sub.-- Kab=M.sub.-- Mot*.mu.+M.sub.-- Kzu-M.sub.-- J for release gear changes,
• (4) a torque converter step-up ratio (.mu.) is determined from a torque converter characteristic with the parameters (n.sub.-- Mot) and (n.sub.-- T) and
• (5) a deceleration torque (M.sub.-- J) is determined as a function of parameters comprising engine torque (M.sub.-- Mot) and gearbox output rotational speed (n.sub.-- Getr.sub.-- aus),
• and that the required deceleration value is formed from a required value of the gearbox input rotational speed, from the deceleration torque (M.sub.-- J), from the mass moment of inertia (I) of the rotating masses and taking account of at least one delay time under conditions such that ##EQU2## (7) the deceleration torque (M.sub.-- J) is determined as a function of parameters such as the gearbox output rotational speed (n.sub.-- Getr.sub.-- aus) and the engine torque (M.sub.-- Mot), and
• (8) a delay element is arranged either before or after an integrating element for the formation of the required value,
• or, in lieu of conditions (7) and (8),
• (9) the deceleration torque (M.sub.-- J) is determined from the required value determined by the correction value and from the torque of the gearbox input shaft, where
• (10) a required value for the transmission torque is equal to M.sub.-- K.sub.-- soll.sub.-- verz=p.sub.-- K.sub.-- soll*C.sub.-- Kzu for change-up operations, and
• (11) M.sub.-- K.sub.-- soll.sub.-- verz=p.sub.-- K.sub.-- soll*C.sub.-- Kab for release gear changes, and
• (12) M.sub.-- J=M.sub.-- K.sub.-- soll.sub.-- verz-M.sub.-- Mot*.mu., and
• (13) a proportional element for formation of a delayed required value of the transmission torque in accordance with one of the conditions (10) and (11) is arranged before or after a delay element.