Automatic clutch control

A method for automatically controlling the operation of a master friction clutch in a vehicle automatic mechanical transmission system of the type comprising an automatic mechanical transmission, a throttle device controlled heat engine, a master clutch interposed the engine and transmission and a control system including means for receiving sensed or calculated input signals indicative of clutch, engine and transmission operating condition, means for processing said input signals in accordance with predetermined logic rules, and means for providing output signals to command the operation of a clutch actuator means to manipulate said clutch to a first fully engaged condition, a second fully disengaged condition and a third partially engaged condition, said control system having at least one mode of operation for causing said clutch to assume said fully engaged condition in a modulated manner in accordance with said input signals and predetermined logic rules, said one mode including causing said actuator to manipulate said clutch from the second fully disengaged to about the incipient engagement position thereof in a nonmodulated rapid manner and then manipulate said clutch from the incipient engagement position to the fully engaged condition thereof in a modulated manner in accordance with said logic rules;

• said method characterized by:
• determining the incipient engagement position of said clutch by:
• sensing the current value of a first parameter indicative of clutch actuator condition;
• monitoring the value of a second parameter indicative of the rate of the rate of change of engine speed;
• selecting a first reference value equal to the predicted value of said second parameter at the time of incipient engagement of said clutch;
• determining the value of said first parameter at the time of the value of said second parameter equaling said first reference value;
• periodically setting a second reference value to the value of said first parameter at the time or the value of said second parameter equaling said first reference value;
• storing data including at least the most recently determined second reference value;
• and
• comparing said current value of first parameter to said second reference value.