Supercharging system for automotive engines

Claim 1

A supercharging system for an automotive engine comprising: a turbocharger driven by exhaust-gas of the engine; a supercharger; an intake passage connecting the turbocharger and the supercharger in series, for supplying air to the engine; driving means for driving the supercharger by the engine; clutch means provided in the driving means; a first bypass provided around the supercharger; a control valve provided in the first bypass; a second bypass provided around the turbine of the turbocharger; a waste gate valve provided in the second bypass; a first actuator for operating the control valve; a second actuator for operating the waste gate valve; first means for operating the second actuator to open the waste gate valve when supercharging pressure exceeds a predetermined value; an engine speed sensor for detecting speed of the engine; an engine load sensor for detecting load on the engine; a control unit responsive to output signals of the engine speed sensor and engine load sensor for operating the clutch means and first actuator; the control unit including second means for disengaging the clutch means at light load on the engine in a predetermined low engine speed range, third means for engaging the clutch means at heavy load in the low engine speed range, fourth means for disengaging the clutch means in a predetermined high engine speed range; fifth means for controlling the opening of the control valve in accordance with variation of engine speed and load when the engine operation is in a transient state.