| 摘要 |
PROBLEM TO BE SOLVED: To prevent leakage ultrasonic waves from spreading through a flow meter main body or a vortex generator. SOLUTION: In an ultrasonic vortex flowmeter 10, an exciting force of a piezo-electric element 70 is transmitted to a diaphragm 72c, whereby ultrasonic waves are emitted into fluid, and the leakage ultrasonic waves spread to a holding member 39 through a cylindrical section 72a of a sensor holder 72 and a covering member 78. Each fluid in channels 18, 20 is supplied to a space 38c, whereby the diaphragm 72c and the covering member 78 are placed under the same pressure, and the strength of a conduit line 78b can be reduced. Therefore, the cross-section area of wall thickness of the conduit line 78b being perpendicular to the axis of the conduit line 78b is made smaller than the cross-section area of wall thickness of the cylindrical section 72a being perpendicular to the axis of the cylindrical section 72a. Thus, the ultrasonic waves leaking from the cylindrical section 72a is attenuated at the conduit line 78b in accordance with the reduced cross-section area. As a result, leakage sonic waves from the sensor holder 72 to a sensor mounting section 38 are decreased, and a sufficient S/N ratio is assured. COPYRIGHT: (C)2005,JPO&NCIPI
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