Control for automatic mechanical transmission system start from stop operation

Claim 1

Claim 1. A method for controlling a vehicle start from stop system (10) for vehicles having an operator actuated throttle pedal (24), a fuel control (26) for controlling the amount of fuel supplied to a fuel controlled engine (14), a transmission (12) having a plurality of gear ratio combinations selectively engagable between a transmission input shaft and a transmission output shaft (20), said transmission input shaft being operatively connected to said engine by means of a selectively engagable and disengagable friction clutch (16), said start from stop system comprising an information processing unit (42) having means for receiving a plurality of input signals including an input (N) signal indicative of the rotational speed of the engine and an input signal (THL) indicative of the operator setting of the throttle pedal or of the engine torque, said processing unit including means for processing said input signals in accordance with predetermined logic rules for generating command output signals whereby said system is operated in accordance with said logic rules, and means (26, 30, 34) associated with said system effective to actuate said transmission system in response to said command output signals from said processing unit; said processing unit having means to sense vehicle start from stop operation and, in a vehicle start from stop operation, issuing command output signals to clutch control means (30) for controlling the rate of engagement of said clutch and to fuel control means (26) for controlling the amount of fuel (FC) supplied to said engine; the method characterized by: setting a target engine speed value (A) as a function of the operator setting (THL) of the throttle pedal (138, 140) or as a function of the engine torque; modulating the amount of fuel supplied to the engine to cause the engine speed to rapidly, in a damped manner, substantially equal said target engine speed and then modulating the amount of fuel to said engine to cause said engine speed to be maintained at said target engine speed value (146, 148); and causing said clutch to engage at a first rate of engagement (106) until engine speed (N) has been caused to equal and be maintained at said target value (A) and the amount of fuel (FC) currently being supplied to the engine is equal to or greater than said reference value (REF), then causing said clutch to be engaged at a second (126) more rapid rate of engagement.