To improve a transient responsiveness characteristic of boost pressure in an engine for controlling an intake amount by rotation of a supercharger.
This device is provided with a bypass passage 11 for bypassing a supercharger 7, a bypass valve 12 for regulating an opening of the bypass passage, and an electric motor 9 for driving the supercharger. At a steady operation time judged from an accelerator operation amount and the like, the bypass valve is opened to an opening degree calculated according to target boost pressure, and rotating speed of the supercharger is controlled by the electric motor so as to obtain target boost pressure by the bypass valve opening in this time. When a demand load is increased by an accelerating operation and the like from this condition, the bypass valve opening is corrected to the reducing direction, and the target boost pressure is controlled to rotating speed of the supercharger so as to achieve the target boost pressure. The bypass valve opening is reduced at initiation of a transient condition of acceleration and the like, and thereby a bypass air amount of the supercharger is immediately reduced. It is thus possible to exhibit good supercharging responsiveness.
IWANO HIROSHI
KAZAMA ISAMU
ISHINO TAKESHI
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