| 摘要 |
PROBLEM TO BE SOLVED: To provide an air/fuel ratio controller capable of intaking a sufficient quantity of air, cooling a solenoid valve sufficiently and adequately controlling air/fuel ratio. SOLUTION: In the air intake pipe 3 of a general purpose engine 1, air is supplied to the downstream side of a venturi part 7 and in order to regulate the fuel mixing ratio, a by-pass circuit 19 is provided for detouring the venturi part 7 and a throttle valve 17. This by-pass circuit 19 is so formed as covering a part of a pipe wall of the air intake pipe 3. In this device, since an air/fuel ratio is controlled within a range of A/F=13.5-14, an effective sectional area from the entrance 19a of the by-pass circuit 19 to its outlet 19b is set to 70 mm<2> , the effective sectional area from the entrance 19a to its outlet 19b in the air intake pipe 3 is set to 175 mm<2> , and accordingly the ratio of effective sectional area between the by-pass circuit 19 and the air intake tube 3 is set to 1:2.5 (40%). |
