Intake air control system for an automotive engine having a turbocharger

Claim 1

In an intake air control system for an automotive engine having an accelerator pedal, a throttle valve provided in an intake pipe of the engine and operatively connected to the accelerator pedal by a connecting rod, a turbocharger including a turbine operated by exhaust gas of the engine and a compressor provided in the intake pipe and driven by the turbine to compress intake air, a wastegate provided in a first bypass around the turbine, and actuating means communicating with the intake pipe downstream of the compressor through a passage for actuating the wastegate when pressure of the intake air compressed by the compressor becomes higher than a predetermined value, the improvement in the system which comprises a second bypass around the compressor, a control valve disposed in the second bypass, and connecting means for operatively connecting the control valve with the connecting rod and for closing the control valve when the accelerator pedal is depressed beyond a predetermined degree, the latter representing a partial load of the engine with the control valve being open so as to return surplus of said intake air compressed by the compressor to the compressor through the second bypass so as to reduce pumping loss of the turbocharger, to minimize time lag in the turbocharger at change from low engine speed to high engine speed, and to improve combustion efficiency of the engine, and the connecting means comprises a lever operatively engaged with the connecting rod and arranged to be pivoted when the accelerator pedal is depressed beyond said predetermined degree, and a cable connected between the lever and the control valve so as to close the control valve in dependency on pivoting of the lever.