| 摘要 |
<p>PURPOSE:To reduce the consumption power of a battery serving as a heat source for heating secondary air so as to prevent the secondary air supply device from greatly increasing its size, while promoting the early stage activation of precatalyst and main catalyst. CONSTITUTION:A secondary air supply passage 20 is branched into branch passages just upstream of precatalyst 16 and main catalyst 18 and connected thereto. An electrical heater 28 is provided downstream of an air pump 22 connected in the supply passage 20. First and second branch passages 20a, 20b of the secondary air supply passage 20 are provided in their branching parts with first and second cut-valves 30, 32. After an engine starts, if it is in a working range for secondary air supply, the first cut valve 30 is opened in such a condition that the second cut valve 32 is held to be closed, and thereafter, the air pump 22 is operated while the electrical heater 28 is energized. After a predetermined time elapses from the start of the operation of the engine 12, the first cut valve 30 is closed while the second cut valve 32 is opened.</p> |
