PURPOSE: To activate an electrification heating type catalyst by small power in an early stage while reducing a battery load so as to reduce exhaust emission when battery voltage is lowered.
CONSTITUTION: First and second electric heater catalysts (EHC) 19, 20 are arranged in the exhaust system of right and left banks 2, 3 of a V-type engine. Respective EHCs 19, 20 are electrically connected to a battery 29 in parallel, and electrified by respecctive relay switches 32, 33 selectively. When it is judged by an ECU 81 that voltage of the battery 29 is reduced on the basis of detection of a voltage sensor 63 it blocks, electrification to the first EHC 19 in which an introduced exhaust temperature is low relatively and controls respective relay switches 32. 33 so that electrification only to the second HEC 20 is allowed. Therefore, in the second EHC 20 to which electrification is allowed, power of the battery 29 whose voltage is reduced is used effectively for heating so as to promote heating and warming-up operation in parallel with exhaust of high temperature.
YOSHIZAKI KOJI
TANAKA SHINICHIRO
HIBINO MASAHIKO
