| 摘要 |
PURPOSE:To suppress the generation of exhaust smoke through a vibration reducer including an intake air throttle valve for constricting an intake passage in the low speed and load operation of an engine, by providing a by-pass around the throttle valve, installing a restrictor valve in the by-pass and controlling the degree of opening of the latter valve depending on the degree of nontransparency of exhaust gas. CONSTITUTION:A by-pass 16 is provided around an intake air throttle valve 2 installed in the halfway part of an intake passage 1. An electromagnetic restrictor valve 17 is provided in the by-pass 16. This minimum degree of opening of the valve 17 is predetermined so that a prescribed quantity of intake air is introduced through between the body 18 of the valve and the wall surface of the by-pass 16. Photoelectric elements 20, 21 are provided in the halfway part of an exhaust passage 14 to detect the degree of nontransparency of exhaust gas downstream to a muffler 19. The output of the light receiving element 21 is applied to a smoke quantity discrimination circuit 31 through a power amplifier 30. When the circuit 31 has judged that the degree of nontransparency of exhaust gas has exceeded a prescribed level, a solenoid valve 17 is energized through a relay 32 to open the by-pass 16. |
