Patent ID: 8162286

Claim:
A piezoelectric driven control valve comprising: (a) a body provided with a valve seat formed at a bottom of an upward-opened valve chamber formed in the body; (b) a metal diaphragm disposed inside the valve chamber so as to contact the valve seat through a downward pressure and to be separable from the valve seat due to a first elastic force of the metal diaphragm when the downward pressure is absent; (c) a bottomed tubular actuator box supported to move ascendably and descendably on the body, wherein the actuator box has a diaphragm presser disposed at a lower end of the actuator box so that the diaphragm presser contacts an upper surface of the metal diaphragm; (d) a split base fixed to the body and having an upper wall, wherein the upper wall of the split base is inserted into an elongated guide hole that is formed in a peripheral wall at a lower end portion of the actuator box so that the upper wall of the split base faces an upper surface of a bottom wall of the actuator box; (e) a disc spring provided between the bottom wall of the actuator box and the upper wall of the split base, wherein the disc spring exerts a second elastic force that presses and urges the actuator box downward so as provide via the diaphragm presser the downward pressure that brings the metal diaphragm into contact with the valve seat; (f) a piezoelectric actuator housed inside the actuator box, wherein an upper end of the piezoelectric actuator is supported positionably at an upper portion end of the actuator box, and wherein a lower end of the piezoelectric actuator is supported on the upper wall of the split base, and wherein the piezoelectric actuator is extended upward with application of a voltage to piezoelectric elements in the piezoelectric actuator so as to press the actuator box upward against the second elastic force of the disc spring so that the downward pressure is absent and the metal diaphragm separates from the valve seat due to the first elastic force of the metal diaphragm; and (g) a precompression mechanism is provided between the upper wall of the split base and the lower end of the piezoelectric actuator, wherein the precompression mechanism is disposed to apply a compression force constantly to the piezoelectric elements in the piezoelectric actuator.