| 摘要 |
PURPOSE:To hold the air-to-fuel ratio at a proper rate by installing a counterflow preventive member in a by-pass air passage and by preventing malfunction of the airflow meter owing to counterflow. CONSTITUTION:The upper flow of a venturi part 4 and the narrowest part of the same 4 are in communication through a by-pass air passage 5, and a heat radiation flowmeter 6 is installed on its midway. The output of this flowmeter 6 operates a proportional solenoid valve 23 with the aid of a computer 9 so that the rate of air flow will become constant. Pulsation and counterflow of the intake air stream generated when the engine is full open for low speed operation permits the flowmeter 6 to output a signal as a large rate of air flow and, thus, a rich mixture gas is supplied to the engine, and therefore a cylindrical convolution chamber 30 is provided in order to prevent it. Accordingly a counterflow flows in the convolution chamber 30 in its tangential direction, so that a large fluid resistance is produced to hinder generation of counterflow in the by-pass air passage 5. |
