PURPOSE: To heat a riser section of an intake pipe promptly and to thereby improve the engine starting performance, by forming a riser heating water passage in the intake pipe, and communicating the passage with a water jacket for cooling an engine and a cooling water storing, heat-insulating tank.
CONSTITUTION: In case of cold starting of an engine, changeover valves 7, 8 are shifted by a control unit 13 such that their ports 7b and 7c and ports 8b and 8c are respectively communicated with each toher. At the same time, a water pump 10 is set into operation and a changeover valve 9 is closed. Resultantly, the temperature of a riser section 2a can be raised by feeding cooling water kept at a relatively high temperature in a cooling water storing, heat-insulating tank 5 to a riser heating water passage 4. By thus promoting vaporization of fuel supplied from a carburetor 1, engine can be warmed up efficiently without causing misfiring. Subsequently, when the temperature of cooling water has become higher than a prescribed value, the valves 7, 8 are shifted such that their ports 7aW7c and 8aW8c are all communicated with each other. At the same time, operation of the water pump 10 is stopped and the changeover valve 9 is closed.
KONDOU YASUO
NAKAGAWA MITSURU
KATOU YOUJI
NIPPON DENSO CO
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