| 摘要 |
PURPOSE: To markedly recuce an operating input when starting action, by forming a diameter in a point end of a seat of a negative pressure controlling seal valve almost equal to or less than a diameter formed by a diaphragm between a control valve and an internal peripheral side of a cylindrical part. CONSTITUTION: A cylinder part 19a and a bead part 19b, playing a role of diaphragm, are provided in a control valve in a cylindrical part, to provide an atmospheric seal part 19c and a negative pressure seal part 19d in a front side end. When a rod 17 is operated, the negative pressure seal part 19d comes into contact with a negative pressure controlling seal valve 15a of almost the same small diameter, to interrupt a change pressure chamber 13 from a fixed negative pressure chamber 12, and a plunger atmospheric controlling seal valve 16a is lifted from the atmospheric seal part 19c of the control valve, to increase a pressure of the change pressure chamber 13. This propulsive force is transmitted to an output member 25 through a rubber disk 26. Since operating resistance in this stage is almost not changed, an operating input at starting of action is markedly reduced. |
