| 摘要 |
PURPOSE:To make the air-fuel ratio control speed of a suction secondary air feeder settable in an optional manner, by selecting each pressure passage provided with an orifice, which interconnects a suction port and an exhaust port feeding an air control valve with control pressure, by means of a solenoid valve. CONSTITUTION:When a control circuit 22 reads out an output voltage level of an oxygen density sensor 23 and feeds a driving circuit 21 with a lean or rich signal, the circuit 21 makes a solenoid valve 13 come into a state of being unoperated or operated according to the signal given. Now, when the output of the control circuit 22 turns over from the lean or rich signal, the solenoid valve 13 comes into a state of being operated, closing the side of an atmospheric pressure passage 16 and connecting a pressure passage 14 to a suction pressure passage 15, and suction pressure Pe is fed to a suction pressure chamber 12a from a suction pressure controlling part 31 via an orifice 17, approaching closely to the suction pressure pe, whereby the opening of an air control valve 12 or the flow passage area of a suction secondary air passage 11 increases, making the secondary air quantity grow large, so that such a quantity of secondary air as being proportioned to a main suction air quantity is fed to an engine 4. Therefore, a control speed can be optionally altered according to size of the orifice's passage area. |
