PURPOSE: To heat a catalyst with a high efficiency while suppressing consumption of power by providing an electrification control means for controling electrification of the heating means of the catalyst according to operating condition of an engine rotational speed sensor and that of an engine load sensor.
CONSTITUTION: In the intake passage 2 of an engine main body 1, an air cleaner 4, an air flow sensor 5, a throttle valve 6, and a surge tank 7 are provided in order from the upstream side thereof. In an exhaust passage 3, an O2 sensor 8, a pre-positioned catalyst 9 with a heater, and a main catalyst 10 are provided in order from the upstream side thereof. A temperature sensor 11 for detecting the temperature of the per-positioned catalyst 9 with a heater is provided thereon. An engine rotational speed sensor and an engine load sensor are used as operating condition detecting means. Electrification of the heater of the catalyst 9 is controlled by a control unit 18 according to the operating condition. In such a way, the catalyst 9 is heated with good efficiency while suppressing consumption of power.
KIDO YOSHINOBU
KOUTOKU MASANOBU
TERADA KOICHI
