Boost pressure control system for an engine

Abstract

A boost pressure control system for a vehicle engine equipped with a supercharger and a torque converter having a lock-up clutch, in which the boost pressure is controlled by adjusting the degree of the opening of an air bypass valve and the ON/OFF position of the supercharger in such manner that the different control characteristics of the boost pressure are selected in accordance with whether the lock-up clutch of the torque converter is turned ON or OFF, i.e., when the lock-up clutch is turned ON, the supercharger is started at a lower engine load, and the degree of the opening of the air bypass valve is set smaller, thereby enabling the lock-up operation of the torque converter under running conditions in which a higher driving torque is required and, thereby widening the operating range of the lock-up operation of the torque converter and improving the fuel economy of the vehicle.

Dependencies are inferred from the claim text.