Patent ID: 8678349

Claim:
A pressure-operated control valve comprising: a diaphragm comprised of multilayered metal plates each having a frustum-shaped conical portion and a flat portion or a concave portion at an inside of the conical portion; a valve port formed between a primary port and a secondary port; a valve body configured to open and close the valve port; a valve shaft interposed between the diaphragm and the valve body, and configured to push the valve body onto the valve port due to a reactive force of the diaphragm, the valve shaft having an end face that bears on the diaphragm at the inside of the conical portion; and a coil spring configured to push the valve shaft onto the diaphragm; wherein the diaphragm includes a boundary portion interposed between the conical portion and the flat portion or the concave portion of the diaphragm, and wherein a diameter D of the end face of the valve shaft is larger than a diameter d of the flat portion or the concave portion of the diaphragm at the inside of the conical portion, whereby the boundary portion abuts on an inside of the end face of the valve shaft at the diaphragm side.