CH617750

Apparatus for controlling the air supply to the intake manifold of an internal combustion engine having an intake system comprising a carburetor, the carburetor having a throttle, means for admitting air from the atmosphere and conducting the air to the carburetor for mixing with fuel, and conduit means for conducting the mixture of air and fuel from the carburetor to the intake manifold, the apparatus comprising auxiliary conduit means for conducting fuel-free air into the engine, the auxiliary conduit means communicating with the intake system at a point downstream of the throttle, a displaceable member associated with the auxiliary conduit means, the displaceable member being displaceable between a position in which the member blocks the access of air from the auxiliary conduit to the intake manifold and positions in which the member at least partly opens access of air from the auxiliary conduit to the intake manifold, an electromagnet associated with the displaceable member for controlling the displacement of the member, means for controlling the energization of the electromagnet, the energization controlling means including at least one switch responsive to pressure variations occurring in the intake system, and means for transmitting pressure variations from the intake system to the pressure responsive switch thereby to actuate the pressure responsive switch.