Apparatus for preventing after-fire in an internal combustion engine

Claim 1

In an apparatus for preventing after-fire of an unburnt air-fuel mixture in the intake system of the internal combustion engine due to a misfire in the combustion chambers when the engine begins to decelerate while the throttle valve of the engine is kept in its fully closed position, which apparatus comprises an air control valve capable of being opened for introducing air into the intake system of the engine and a vacuum actuator which includes a spring urged diaphragm connected to the air control valve, which diaphragm forms two chambers on the sides thereof, one of which is connected to a vacuum port formed in the engine intake system, and which diaphragm operates to open the air control valve when a predetermined pressure difference is formed between said chambers due to the engine beginning to decelerate, so that an amount of air is introduced into the engine intake system by the opened air control valve from the beginning of the engine deceleration, thereby preventing a misfire of the air-fuel mixture in the combustion chamber, the improvement that comprises temperature detecting valve means having two valve ports and a temperature sensing valve member for connecting said ports to each other until the engine is fully warmed up, and for thereafter disconnecting said ports from each other, two pipe means, connecting said two valve ports with said two chambers of the vacuum actuator, respectively, whereby said two chambers are connected to each other when the engine is not fully warmed up, in order to cancel the pressure difference between the two chambers.