| 摘要 |
PURPOSE:To contrive to prevent a jet needle from staggering and the like by a structure wherein a chamferred part are formed on the jet needle so that the clearance between the inner periphery of a needle jet and the outer periphery of the jet needle, which vertically moves inside the needle jet, becomes gradually larger toward downwards. CONSTITUTION:A diaphragm valve type carburetor has a jet needle 41, which vertically moves inside a needle jet 17 forming a fuel passage from a diaphragm chamber to a venturi in order to adjust the fuel flow rate, at a part, which faces a throttle valve 4, of a main body 1. In this case, a plurality of machined-off flats 42 are arranged along the outer periphery of the jet needle 41. In addition, the machined-off flats 42 are formed so that the clearance 43 between the bore of the needle jet 17 and the jet needle 41 gradually increases downwards and at the same time the circular arc parts 44 of the jet needle 41 and the needle jet are rendered to be slidable against each other. Due to the structure as mentioned above, the jet needle 41 can be prevented from staggering by the vibration developed with the operation of an engine and at the same time the fuel flow rate can be properly controlled, because the cross sectional area of the clearance 43 can be changed with the vertical movement of the jet needle 41. |
