| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic flowmeter having both a wide measurement range and high measurement accuracy while having a compact composition. SOLUTION: In the ultrasonic flowmeter 100, ultrasonic sensors 2a and 2b are arranged in an upstream side and a downstream side of a communication pipe 10 for communicating a fluid. The ultrasonic sensors 2a and 2b have a structure wherein a piezoelectric element 13 is joined to an acoustic match layer 15. The piezoelectric element 13 has a form of a rectangular parallelepiped wherein electrode forming faces 13p and 13q positioned on both sides in a polarization axis direction comprise a rectangle (excluding a square). A resonance frequency fr<SB>1</SB>of an elongation vibration mode in a long edge direction of the piezoelectric element 13 and a resonance frequency fr<SB>2</SB>of an elongation vibration mode in a short edge direction are selectively used during a high flow rate and a low flow rate. COPYRIGHT: (C)2006,JPO&NCIPI
|
