Patent ID: 6230738
Filing Date: 2001-05-15
Classification: F16K,Y10T

Abstract:
A flow rate control valve for controlling the flow rate of a target fluid to be measured, comprising:an apparatus body having a valve hole;a valve body for opening/closing said valve hole; anda driver including an ultrasonic motor having a rotary shaft for driving said valve body to adjust the opening degree of the valve hole so as to control the flow rate of the target fluid flowing through the valve hole, said driver comprising:a base for rotatably supporting said rotary shaft;an annular stator mounted on one surface of said base and surrounding one end portion, projecting upward through said base, of the rotary shaft;a plurality of piezoelectric elements arranged in the circumferential direction of said stator;a rotor arranged to face the stator and having the central portion fixed to one end portion of the rotary shaft;a pressurizing spring for resiliently pressing the peripheral portion of the rotor against the peripheral portion of the stator; anda high frequency power source for supplying a high frequency voltage to said piezoelectric elements for generating an ultrasonic vibration within the stator so as to rotate the rotor;wherein said piezoelectric elements mounted to said stator are grouped into at least two groups, and high frequency powers differing from each other in phase are supplied from said high frequency power source to the piezoelectric elements of different groups.