| 摘要 |
PURPOSE:To prevent the air/fuel ratio of a mixture from being excessively lean and fluctuating in an engine having a carburettor provided with a throttle valve of butterfly type disposed in an intake-air passage, by providing a resistance valve in the intake/ air passage and as well by laying an atmospheric air communicating passage in the intake air passage between the resistance valve and a fuel jet port. CONSTITUTION:An intake air passage 4 is communicated with a combustion chamber 3 in each cylinder C1, C2 of an engine, and a small venturi 8 provided with a throttle valve 6 and a fuel nozzle 7 is formed in a carburettor 5 which forms a part of the intake air passage 4. Further, there is provided an intake air expansion chamber 10 including a box member 10a and a lid member 10b above the carburettor 5. Further, a resistance valve 16 is disposed in an opening in the upper surface of the above-mentioned box member 10b, and is composed of a support cylinder 17 and a valve member 19 which covers an opening surface 18. A bypass passage is formed by the opening surface 18, a gap 23 and a circular hole formed in the valve member 19. With this arrangement, an increase in the flow of intake air is temporarily hindered by the resistance valve 16 when the throttle valve 6 is abruptly opened upon enging abrupt acceleration, thereby the air/fuel ratio of a mixture is prevented from being excessively lean. |
