| 主权项 |
1. A fluid control device, comprising:
a body in which a fluid passage is disposed; a casing disposed above the body; a valve body which opens and closes the fluid passage; a valve rod which moves upward and downward so as to move the valve body in an opening or closing direction; a first piston disposed at the valve rod; and a piston driving unit which drives the piston by introducing driving gas into a driving gas introducing chamber formed below the piston and applying driving gas to the piston, wherein:
the casing is formed so as to be opened upward; andthe first piston is disposed at an upper end portion of the valve rod such that a piston upper end portion is exposed from an opening of the casing when the valve rod is located at an upper position; a second piston is disposed also at an intermediate portion of the valve rod; a through hole is disposed at the piston which is disposed at the valve rod upper end portion, the valve rod upper end portion being inserted into a lower portion of the through hole; an upper portion of the through hole is configured to be a driving gas introducing portion with which a piping for introducing the driving gas can be connected, a first driving gas introducing chamber is formed below the first piston, and a second driving gas introducing chamber is formed below the second piston; and an axial direction passage which extends downward from the driving gas introducing portion, and a radial direction passage which communicates with each driving gas introducing chamber from the axial direction passage are formed inside the valve rod, wherein the first piston comprises a body to form the first driving gas introducing chamber and a flange disposed at the upper end portion of the body, an O-ring is disposed between an outer circumference of the body and the casing, and the flange is exposed from the opening of the casing, characterized in that an outer diameter of the body of the first piston is equal to an inner diameter of the casing, an outer diameter of the flange of the first piston is larger than the inner diameter of the casing and the driving gas introducing portion with which the piping for introducing the driving gas can be connected is provided in the body of the first piston which moves vertically, so that the first piston has function such as forming a driving gas introducing chamber, forming a driving gas introducing portion and forming a visual checking member. |
