PURPOSE: To improve the durability of a supercharger and to increase the engine output, by providing a trouble detecting means for detecting the fact that a subsidiary throttle valve is kept open by some trouble and a supercharging pressure restricting means operated when said trouble detecting means detects occurrence of trouble with the subsidiary throttle valve for keeping the supercharging pressure lower than a prescribed value.
CONSTITUTION: The intake system of an engine 1 is constituted by a main intake system 2 having a main throttle valve 10 and a subsidiary intake system 5 having a subsidiary throttle valve 20 and a supercharger 18. If the subsidiary throttle valve 20 is kept colsed by some trouble, a sensor 37 is turned ON and a supercharging pressure restricting means 35 is turned OFF in response to the output of the trouble detecting means 34. Further, transmission of a clutch signal from a potentiometer 32 to an electromagnetic clutch 26 is interrupted, so that operation of the supercharger 18 is stopped. Through employment of such an arrangement, it is enabled to prevent degradation in durability of the supercharger 18 and drop of the engine output due to driving of the supercharger 18 under a high supercharging pressure.
SATOU HARUHIKO
OKIMOTO HARUO
SAKURAI SHIGERU
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