Control of vacuum in inlet manifold of lean-burn internal combustion engine in vehicle having vacuum-assisted braking servomechanism

摘要

The engine has a vacuum-assisted brake servomechanism (16,17). When the engine (1) is operating in lean mode the operation of the brake pedal (15) is detected and the time elapsed since the operation is measured. When this elapsed time exceeds a threshold the motor is switched to a richer operating mode to increase the vacuum and thus the level of braking assistance.