Ultrasonic flow meter unit with an insulating damping member covering the ultrasonic transducers, a measuring circuit and lead wires

1. An ultrasonic flow meter unit mounted to a fluid passage through which a measurement target fluid flows, the ultrasonic flow meter unit comprising:

a pair of ultrasonic transducers each including a piezoelectric substrate which generates an ultrasonic pulse, and an acoustic matching member, the pair of ultrasonic transducers being placed on the fluid passage such that the ultrasonic transducers mutually transmit and receive the ultrasonic pulse;

a measuring circuit which is placed to connect with the fluid passage, and measures a flow of the measurement target fluid based on time for which the ultrasonic pulse propagates between the pair of ultrasonic transducers,

wherein the measuring circuit and the pair of ultrasonic transducers are spaced apart from each other; and

an insulating damping member arranged to cover both the measuring circuit and the pair of ultrasonic transducers such that the insulating damping member selectively covers the pair of ultrasonic transducers by contacting a mounting member arranged between each ultrasonic transducer and the fluid passage and covering the piezoelectric substrate, wherein the insulating damping member is arranged adjacent to the acoustic matching member without contacting the acoustic matching member.

2. The ultrasonic flow meter unit according to claim 1 , further comprising:

a lead wire electrically connecting the piezoelectric substrate to the measuring circuit;

wherein the insulating damping member is arranged to further cover the lead wire.

3. The ultrasonic flow meter unit according to claim 2 , further comprising ultrasonic transducer mounting members arranged between the fluid passage and a control board where the measuring circuit is mounted, the ultrasonic transducers mounted and jointed to the ultrasonic transducer mounting members, wherein each ultrasonic transducer mounting member comprises a protruding contact portion which contacts, via a hole of the control board, the insulating damping member arranged to cover the measuring circuit.

4. The ultrasonic flow meter unit according to claim 1 ,

wherein each of the ultrasonic transducers further includes a metal plate; and

wherein the acoustic matching member is fastened to one of surfaces of the metal plate, and the piezoelectric substrate is fastened to the other surface of the metal plate.

5. The ultrasonic flow meter unit according to claim 1 ,

wherein each of the ultrasonic transducers further comprises a metal case including a tubular side wall, a flat plate top portion which covers an opening at one end of the side wall, and a support portion extending outward from the other end of the side wall; and

wherein the piezoelectric substrate is fastened to an inner surface of the top portion in a position which is inward relative to the side wall, and the acoustic matching member is fastened to an outer surface of the top portion.