PURPOSE: To remove water left in an engine positively, by continuing operation of the engine when a key switch is turned OFF in the state that water is left in the engine in an apparatus for preventing knocking of engine by injecting water into an intake passage.
CONSTITUTION: When an engine is operated in a region where knocking is possibly caused, a first driving circuit 26 opens a solenoid valve 21 by applying a control signal to a water feeding means 14 in response to the outputs of an engine-speed sensor 33 and a vacuum sensor 32. Thereupon, water in a float chamber 16 is injected from a nozzle 20 opened in a venturi 13, and knocking of an engine is prevented by the presence of water A supplied to a combustion chamber 9 and by the temperature drop of intake air. Here, if a key switch 29 is turned OFF in the above state, the solenoid valve 21 is closed. However, since a delay circuit 30 is set into operation in response to the output signal of a humidity sensor 31 and a fuel injection nozzle 8 and an ignition plug 12 are energized continuously for a prescribed while, water in an engine can be removed completely.
FUJIMOTO MISAO
MASUDA TOSHIHARU
