A booster coil is stored in a coil storing room provided in the bottom section of a common case having an opening on one side, and is insulation-molded with a filler. Unlike conventional three-way poppet valves wherein both inlets can be open to the outlet at the same time during movement of the poppet, the valve according to the present invention can be configured to close both inlets prior to opening one of the inlets to the outlet. The structure has a thin steel pipe.