Supercharging pressure control method for internal combustion engines

Abstract

A method of controlling supercharging pressure in an internal combustion engine wherein the supercharging pressure created by a supercharger is controlled based on a basic control amount determined in dependance on operating conditions of the engine. The basic control amount is corrected in response to the difference between an actual value of the supercharging pressure and a desired value thereof when the engine is in a feedback control region. The basic control amount is corrected in accordance with the rate of change of the supercharging pressure when the engine is in an operating condition immediately before the feedback control region. The supercharging pressure is controlled based upon a second basic control amount other than the first-mentioned basic control amount when the supercharging pressure is below a predetermined value determined by the engine rotational speed and the rate of change of supercharging pressure in the above operating condition. The feedback control is started on condition that the actual supercharging pressure has increased above a second predetermined value set depending upon operating parameters of the engine and a parameter representative of an environmental condition of the engine. The feedback control is started when a predetermined period of time has elapsed after the supercharging pressure has increased above the second predetermined value. The feedback control is effected when the supercharging pressure is in a steady state, while the supercharging pressure is controlled in open loop mode when it is in a transient state.