To efficiently purge a canister means of small heater power.
Evaporative fuel from a fuel tank 11 in an internal combustion engine 100 is introduced through breather piping 13 to the canister 10 to be adsorbed by adsorbent 50a and 50b in the canister. During operation of the internal combustion engine, a purge control valve 15 is opened, and a CCV 17 is opened to introduce atmospheric air into the canister for purging evaporative fuel from the adsorbent. Heaters 20a and 20b to heat the adsorbent, and an intake oxygen concentration sensor 33 to detect concentration of evaporative gas in purge gas are provided, so that the heaters are energized by an electronic control unit(ECU) 30 for heating the adsorbent when the concentration of evaporative fuel is between an upper limit value and a lower limit value prescribed. For the heater 20b for heating the adsorbent 50b at a part of the canister where atmospheric air flows in from the CCV, the lower limit value is set to be higher than the lower limit value for the heater 20a for the adsorbent 50a at a part where evaporative fuel flows in from the breather piping.
YOSHIOKA MAMORU
KIMURA MASAHIRO
