| 摘要 |
PCT No. PCT/FI90/00009 Sec. 371 Date Aug. 23, 1991 Sec. 102(e) Date Aug. 23, 1991 PCT Filed Jan. 10, 1990 PCT Pub. No. WO90/08283 PCT Pub. Date Jul. 26, 1990.The invention relates to a motor-driven control valve for a liquid, in which a control member (31) effects a rotatory and/or linear motion. In order to achieve an improved torsion moment and controllability, the motion of the control member is produced by means of an ultrasonic motor. In one embodiment, the rotating plate acting as a control member (31) forms directly a mobile part of the ultrasonic motor. An oscillating body (36) is in contact with this part, the oscillations of the body being produced by piezoelectric elements (37). The oscillating body (36) with the piezoelectric elements (37) can be annular, thus surrounding e.g. the material flowing in the pipe. Owing to the invention, a compact and simple solution is provided, and the actuating of the plate does not require as many transmission elements as when usual electric motors are being used.
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