Abstract: In a solenoid valve, a desire valve stroke width may be set, and a flow rate may be returned to an original flow rate even when that the flow rate is changed. A solenoid valve includes a drive portion having a bobbin including a slidable hole formed there through, a fixed iron core disposed with in the bobbin and a movable iron core disposed to be slidable within the slidable hole, and a valve function portion having a valve body extending from the movable iron core and disposed in a leading end of a valve shaft passing through the fixed iron core and a valve seat with which the valve body is brought into close contact and from which the valve body is separated. In the solenoid valve, a predetermined gap width is formed between the valve body and the valve seat, when the solenoid valve is not energized, to open the valve, and the movable iron core is drawn to the fixed iron core when the solenoid valve is energized to close the valve.

Abstract: An air fuel ratio control apparatus readily satisfies an emission requirement and is particularly preferable for small-displacement engines. The air fuel ratio control apparatus for an engine includes a fuel control member disposed in a fuel passage delivering fuel from a fuel metering chamber of a carburetor supplying the fuel to a suction passage of a comparatively small engine such as a general purpose engine, a working machine engine and the like, a combustion gas sensor disposed in an exhaust pipe in the engine, and an electronic control unit. The control unit actuates the fuel control member in response to a concentration of a combustion gas component in an exhaust gas detected by the combustion gas sensor so as to control a fuel flow rate.