PURPOSE: To always assure a specified amount of assisting air without being influenced by a variation of a flow rate of air flowing in a bypassing passage by a method wherein an upstream end of an assisting air passage is opened into a suction passage at an upstream side higher than an upstream end opening of the bypassing passage having an opening or closing means disposed therein.
CONSTITUTION: Each of an air suction passage 3 and an air discharging passage 4 is connected to a combustion chamber 2 of an engine 1. An air cleaner 5, a throttle valve 6 and a fuel injection valve 7 are disposed in sequence from the upstream side in the air suction passage 3. The first bypassing passage 11 bypassing the throttle valve 6 and connecting an upstream and downstream parts of the throttle valve 6 in the air suction passage 2 is disposed. An idling speed control valve 12 acting as an opening or closing means is disposed in the bypassing passage. In this case, an assisting air passage 15 for use in supplying assisting air into the fuel injection valve 7 is connected to the fuel injection valve 7 at its downstream end and in turn an upstream end opening 15a is opened at the air suction passage 2 upstream of the upstream end opening 11a of the bypassing passage 11.
MATSUMOTO HIROYUKI
TAKEDA TOSHIO
KIDO YOSHINOBU
MAZDA MOTOR