PURPOSE: To make the effect of engine brake satisfactory, by providing such an opening degree subtracting means that the set opening degree of a throttle valve is gradually reduced upon lowering of load to set a computed opening degree, and as well such an opening degree holding means that, when the computed opening degree reaches a predetermined opening degree, the predetermined opening degree is held as the computed opening degree.
CONSTITUTION: A control means 13 in a control unit 15 receives outputs from a throttle valve opening degree sensor 8, an idle switch 9, a lead detectibg means 21 and an engine rotational speed sensor 12, and controls a throttle valve controlling actuator 4 in accordance with the deviation between the actual opening degree of the throttle valve and the desired (idle) opening degree thereof. The control means 13 is connected with an opening degree subtracting means 26 which gradually reduce a first set opening degree to set a computed opening degree upon lowering of load, and an opening degree holding means 27 which holds a second set opening degree when the computed oening degree reaches the second set opening degree which is smaller than the first set opening degree. Further, when the computed opening degree is larger than the desired opening degree, a dashpot control means 24 delivers an opening signal in dependance upon the difference between the computed opening degree and the actual opening degree.
HASHIMOTO TOORU
NAKAMURA SHIGEO
SAITOU YASUHIKO
