Flow control device

摘要

A flow control device wherein an operating shaft having two valve bodies is actuated by a single stepping motor to control the flow rate of fluid flowing through at least two by-pass passages. A portion of the operating shaft is supported by a first bearing member located in a boundary portion between a casing with the stepping motor incorporated therein and an air dispensing housing, and the shaft portion of the operating shaft located between the two valve bodies is supported by a second bearing member disposed in the interior of the housing. The two valve bodies are centrally provided with axial holes, through which is inserted the operating shaft to fix the valve bodies replaceably. The second bearing member is formed in the shape of a bottomed cylinder having a flange portion at a free end of the cylindrical portion, and at this flange portion the second bearing member is held between the casing and the housing together with the first bearing member. And a valve seat which controls the flow rate of air in cooperation with one of the two valve elements is supported replaceably by the cylindrical portion of the second bearing member.