Brake negative pressure control apparatus and method, and engine control unit for internal combustion engine

摘要

A brake negative pressure control apparatus and method, and an engine control unit for an internal combustion engine are provided for ensuring a negative pressure within a brake booster and a stable combustion while avoiding a complicated control. The brake negative pressure control apparatus and method, and engine control unit are for use with an internal combustion engine of an in-cylinder direct fuel injection type which is configured to set a combustion mode to a stratified combustion or a homogeneous stoichiometric combustion based on a required output in accordance with at least an opening of an accelerator pedal and an operating condition of the internal combustion engine, and is equipped with a brake booster for increasing a braking force of a brake with a negative pressure introduced from an intake pipe. The brake negative pressure control apparatus comprises a negative pressure sensor for detecting a negative pressure within the brake booster, and an ECU for disabling the combustion mode to be set to the stratified combustion when the detected negative pressure is lower than a first predetermined negative pressure. The ECU controls a throttle valve opening in accordance with a target throttle valve opening in a homogeneous combustion mode when the ECU disables the combustion mode to be set to the stratified combustion.