Device for controlling charging pressure of a supercharged internal combustion engine

摘要

An engine comprising a mechanically driven charger arranged in the intake passage downstream of the throttle valve. A bypass passage is branched from the intake passage between the throttle valve and the mechanically driven charger and connected to the intake passage downstream of the mechanically driven charger. A relief valve is arranged in the bypass passage to control the maximum charging pressure produced in the intake passage downstream of the mechanically driven charger. The relief valve is controlled so that the maximum charging pressure is increased when the engine is operating at a low or middle speed, and the maximum charging pressure is reduced when the engine is operating at a high speed.