| 摘要 |
PROBLEM TO BE SOLVED: To reduce operating force in a fully-opened state of a rotary throttle valve type carburetor, and make the rotary throttle valve type carburetor compact. SOLUTION: An engagement recessed part 6d with which an end part of a throttle wire 33 is engaged and a circumferential direction groove 6b on which the throttle wire 33 is wound are formed in an operating lever 6 coupled with a rotary valve element 3. The circumferential direction groove 6b is formed by changing the radius of the circumferential direction groove 6b such that the radius of torque in the operating lever 6 becomes long in the fully-closed/opened state and short at an intermediate point. The operating force in an initial stage of valve opening and the fully opened state can be made low (due to long radius). In particular, since tension of the throttle wire 33 is set to become small in the fully-opened state, operating force in the normal use condition where the fully-opened state is maintained can be reduced, in a small internal combustion engine mounted on a bush cutter or the like. COPYRIGHT: (C)2005,JPO&NCIPI
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