| 摘要 |
PURPOSE:To suppress the torque variation caused by changes in air-fuel ratio by providing a closing valve driven in response to the density of the air-fuel mixture at a branch path provided on a suction port of an engine provided with a helical type suction port and an air-fuel ratio control device. CONSTITUTION:When the air-fuel ratio of the air-fuel mixture fed into a cylinder is reduced lower than a theoretical value, the electric power fed to a solenoid 31 is increased, thus increasing the aperture of a valve port 28 and increasing the air fed through a bypass pipe 26. On the other hand, when the electric power fed to a solenoid 40 is increased, an actuator 37 actuates a rotary valve 18 to open a branch path 14. When the air-fuel ratio of the air-fuel mixture fed into the cylinder is increased larger than the theoretical value, the valve port 28 and the branch path 14 are driven in the closing direction contrary to that mentioned above. When the rotary valve 18 is rotated in the closing direction, the eddy current is strengthened and the combustion speed is increased, and this speed is almost the same as that when a dense air-fuel mixture is being fed, thereby no torque variation occurs even if dilute and over-dense air-fuel mixtures are fed in turn. |
