Reducing i.c. engine intake manifold vacuum at overrunning

摘要

A non-explosive gas (e.g. air) is supplied to the inlet manifold (2) under the control of a valve (13) which is normally closed and is operated by an electrical actuator (16) energized through a circuit including a first switch (19) which closes when the engine speed rises above idling speed and a second switch (20) which closes when the accelerator control moves to its non-operated position. When both switches are closed the valve (13) is opened to admit gas to the manifold, causing the partial vacuum to collapse and thereby preventing fuel from the carburettor (3) reaching the combustion chambers. A further switch (22) may be included in the circuit for protecting a vacuum- braking system by opening when the brake vacuum is below a predetermined value. IMAGE