Patent ID: 7070160
Filing Date: 2006-07-04
Classification: F16K

Abstract:
1. A diaphragm valve comprising: an actuator; and a valve part including: an inlet passage; an outlet passage which is brought into communication with the inlet passage when the diaphragm valve is opened; a valve chamber provided with a valve seat and placed between the inlet passage and the outlet passage; a suck-back chamber placed between the inlet passage and the outlet passage and in vertically aligned relation with the valve chamber; a through hole through which the valve chamber and the suck-back chamber are brought into communication with each other when the diaphragm valve is opened; a first diaphragm which integrally includes a valve element and forms a part of the valve chamber, the first diaphragm being deformable so that the valve element is brought into and out of contact with the valve seat by operation of the actuator; a second diaphragm which forms a part of the suck-back chamber, the second diaphragm being substantially identical in shape to the first diaphragm; and a connecting rod which movably placed through the through hole and connects the first and second diaphragms so that the first and second diaphragms are synchronously deformed by operation of the actuator, thereby changing volumes of the valve chamber and the suck-back chamber in reverse to each other; wherein the diaphragm valve further includes a valve body, the actuator is a piston cylinder assembly including a cylinder integrally provided with the valve body and a piston slidably placed in the cylinder, and the valve element includes an outwardly protruding portion outside the valve chamber, the protruding portion being connected to the piston; and wherein the diaphragm valve further includes a spring in the cylinder, the spring urging the piston toward the first diaphragm, and the cylinder is formed with a pressurizing chamber in which air pressure is applied to the piston from the first diaphragm side to move the piston upward.