| 摘要 |
PURPOSE:To enlarge an adjusting range of operation flow rate, by providing a spiral flow line portion on or adjacent to an inner wall of a cylindrical chamber so as to adjust the operation flow rate by adjusting a sectional area of the spiral flow line. CONSTITUTION:A spring 8 having a fixed element wire diameter and a fixed inside diameter is inserted in a cylindrical chamber 5, and a spiral flow line portion 9 is formed on an inner wall of the cylindrical chamber 5. Both or either of the element wire diameter and/or a pitch of the spring 8 are/is changed so as to change a sectional area of the spiral flow line portion 9 and thereby to adjust operation flow rate to a desired value. Therefore, even when the sectional area of the spiral flow line portion is changed, a sectional area of a cylindrical flow line portion, that is, a viscosity force applying flow line portion is not changed, and lack of viscosity force of gas flow through the cylindrical flow line portion may be eliminated. Accordingly, the operation flow rate of an overflow preventing valve may be set to a large value by increasing an amount of gas flow through the spiral flow line portion. |
