JP2020028059A - Supersonic wave transmitter-receiver - Google Patents

Abstract

To attenuate noise components leaking from a piezoelectric device to the shell side, in a supersonic wave transmitter-receiver for ultrasonic flowmeter originating and receiving an ultrasonic beam into and from liquid flowing through the shell.SOLUTION: A supersonic wave transmitter-receiver 1 includes a piezoelectric device 1b placed in an element housing section 1a, and a metal tube 1f fixed to the rear wall 1e of the element housing section 1a by means of a holding part 1g. The metal tube 1f attenuates noise components by reducing the cross-sectional area, and increasing the length by bending spirally. A lead wire 1j is inserted into the metal tube 1f, one end of the lead wire 1j is connected with the piezoelectric device 1b, and the other end is connected with a terminal, or the like, on the outside of the holding part 1g. Around the metal tube 1f, a protective cylinder 1h fixed to the holding part 1g is placed, and the protective cylinder 1h is filled with an elastic filler 1i, surrounding the metal tube 1f.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ultrasonic transmitter / receiver that can be used particularly preferably when an ultrasonic flowmeter transmits and receives an ultrasonic beam and makes a measurement object a gas.

  An ultrasonic flowmeter propagates an ultrasonic beam through a medium to be measured flowing through a tube, and obtains a flow rate by using a propagation time difference between an ultrasonic beam that goes forward and a backward ultrasonic beam.

  However, when the medium is a gas, it is very difficult to accurately measure the medium with an ultrasonic flowmeter. In other words, since the difference in acoustic impedance between the gas and the ultrasonic transmitter is large, the transmission of the ultrasonic beam from the ultrasonic transmitter into the gas and from the gas to the ultrasonic transmitter is poor, and the ultrasonic This is because the magnitude of the transmitted signal of the ultrasonic beam from the transmitter to the other ultrasonic receiver is extremely small as compared with the liquid.

  On the other hand, the ultrasonic transmitter leaks into the tube via the support mechanism, and unnecessary noise components as noise are transmitted to the ultrasonic receiver. This noise component is large compared to the measurement signal obtained by propagating through the gaseous medium. In the ultrasonic receiver, the measurement signal and the noise component are mixed, and the SN ratio becomes small, which adversely affects the measurement accuracy. .

JP 2010-28815 A Japanese Patent No. 6141556

  Patent Literatures 1 and 2 disclose means for solving such a problem. In these Patent Literatures 1 and 2, a mechanism for supporting an ultrasonic transceiver is designed to attenuate a noise component transmitted to a tube due to leakage. For this reason, as a support mechanism for supporting the ultrasonic transceiver, a support having a reduced cross-sectional area is folded back, overlapped and detoured to extend the transmission distance, and a sound absorbing member is interposed between the tube side and Attenuate noise components. However, the structures of the damping mechanisms disclosed in Patent Documents 1 and 2 are complicated.

  An object of the present invention is to solve the above-described problems, effectively attenuate a noise component leaking and transmitting to the tube side by simple means, and to use a gas to be measured, which can be used particularly suitably. It is to provide a sound wave transceiver.

  An ultrasonic transmitter / receiver according to the present invention for achieving the above object transmits and receives an ultrasonic beam in a fluid flowing through a tube, and in an ultrasonic transmitter / receiver for an ultrasonic flowmeter which receives and receives a fluid on a front wall. Element holding section in which a piezoelectric element for transmitting and receiving an ultrasonic beam is disposed, a holding section for attaching to the tube, and a cross-sectional area in which one end is fixed to the element holding section and the other end is fixed to the holding section. Characterized in that the metal tube is detoured by bending and its length is increased.

  ADVANTAGE OF THE INVENTION According to the ultrasonic transmitter / receiver which concerns on this invention, an unnecessary noise component transmitted to a tube body side can be easily attenuated by supporting an element accommodating part with the curved small diameter metal tube.

  Further, when the periphery of the metal tube is surrounded by the elastic filler, the vibration transmitted through the metal tube can be absorbed, and the noise signal can be reduced.

It is a block diagram of a measurement pipe part. FIG. 2 is a configuration diagram of the ultrasonic transceiver according to the first embodiment. FIG. 9 is a configuration diagram of an ultrasonic transceiver according to a second embodiment.

  The present invention will be described in detail based on the illustrated embodiment.

  FIG. 1 is a configuration diagram showing an example of a measurement pipe section of an ultrasonic flowmeter using an ultrasonic transceiver according to the present invention. The two ultrasonic transmitters / receivers 1 are arranged as a pair at two locations on the tube 2 through which the gas whose flow rate is to be measured flows in the direction of the arrow. The ultrasonic transceivers 1 are opposed to each other with the tube 2 interposed therebetween, and the ultrasonic beams B1 and B2 emitted from the ultrasonic transceiver 1 traverse the tube 2 diagonally, and the ultrasonic transmitter / receiver 1 Mounted to receive at.

  A cylindrical mounting portion 4 protruding outward is formed on the tube wall 3 of the tube 2, and the ultrasonic transceiver 1 is provided in the mounting portion 4, and the ultrasonic transceivers 1 are connected to each other by an ultrasonic beam. Through the propagation path W.

  From each of the ultrasonic transceivers 1, for example, ultrasonic beams B1 and B2 of several hundred KHz are alternately transmitted, and received by the ultrasonic transceiver 1 on the partner side. The flow velocity is obtained by measuring the arrival time difference between the ultrasonic beam B1 traveling along the flow of the fluid and the ultrasonic beam B2 going backward to the flow, and further multiplying the cross-sectional area of the tube 2 to measure the flow rate of the fluid. Since the time difference method for measuring the flow velocity is known, its detailed description is omitted.

  The arrangement of the ultrasonic transmitter / receiver 1 is not limited to the position sandwiching the tube 2 as shown in FIG. 1, but a pair of ultrasonic transmitter / receivers 1 is arranged on one side of the tube 2 and the ultrasonic beam B <b> 1 and B <b> 2 may be reflected in a V-shape in the tubular body 2 and enter the ultrasonic transceiver 1 on the other side.

  FIG. 2 is a configuration diagram of the ultrasonic transceiver 1 according to the first embodiment. A piezoelectric element 1b that transmits and receives an ultrasonic beam is fixed in a cylindrical element housing portion 1a made of a metal body whose front and rear ends are closed. The diameter of the element accommodating portion 1a is about 10 mm, the thickness of the front wall 1c is, for example, about 0.5 mm, and the piezoelectric element 1b is adhered to the inside thereof through grease. The thickness of the side wall 1d and the rear wall 1e of the element housing portion 1a is, for example, about 2 mm.

  One end of a metal tube 1f is fixed to a rear wall 1e of the element housing portion 1a as a support mechanism, and the other end of the metal tube 1f is fixed to a plate-shaped holding portion 1g separated from the element housing portion 1a. ing. The metal tube 1f is made of, for example, a metal body such as copper or titanium having an outer diameter of 2.0 mm and an inner diameter of 1.0 mm, and is bent by, for example, winding a spiral of 15 mm in diameter, for example, five times.

A metal tube 1f is used as a support in order to prevent an ultrasonic signal leaking from the piezoelectric element 1b to the tube 2 side and becoming a noise component from being transmitted to the tube 2 via the holding portion 1g as vibration. The metal tube 1f has a small cross-sectional area and a large length by bending to attenuate the transmitted noise component.
The metal tube 1f needs to have rigidity to support the element accommodating portion 1a, and it is desirable to reduce the cross-sectional area in order to attenuate noise components during transmission, and a balance between the two is required.

  The material of the metal tube 1f may be copper, titanium, or another type of metal. Since the metal tube 1f, which is a support mechanism, has a larger noise component attenuation as its length is increased, the metal tube 1f detours between the element housing portion 1a and the holding portion 1g by bending. It is preferable to increase the height. In terms of processing, this bending is preferably a spiral shape as in the embodiment, but is not limited to the spiral shape, and may be a detour shape such as a zigzag fold.

  The connection of the metal tube 1f to the element housing portion 1a and the holding portion 1g is made by, for example, welding. In order to facilitate this welding, it is preferable to select the same type of metal for the metal tube 1f, the element housing portion 1a, and the holding portion 1g.

Around the metal tube 1f, a cylindrical metal protection tube 1h fixed to the holding portion 1g is spaced apart. The front end of the protection cylinder 1h is open, and the front end extends to near the rear end of the element accommodating portion 1a, but does not contact the element accommodating portion 1a.
The protective cylinder 1h is filled with an elastic filler 1i made of, for example, silicone rubber, and solidifies the periphery of the metal tube 1f, holds the metal tube 1f, and also serves as a vibration absorber transmitting the metal tube 1f. Function. The elastic filler 1i is injected in a liquid state into the protective cylinder 1h, and is solidified by heating or natural solidification.

  Although the metal tube 1f suspends and supports the element accommodating portion 1a, the rigidity of the metal tube 1f is high, and the element accommodating portion 1a is hardened around the metal tube 1f with an elastic filler 1i. It does not move or the metal tube 1f does not contact the protection tube 1h.

  Insulated lead wire 1j serving as a signal line is inserted into the metal tube 1f. One end of the lead wire 1j is connected to the piezoelectric element 1b in the element housing portion 1a, and the other end is a holding portion 1g. Outside, is connected to a connector or the like in order to connect to a control circuit unit or the like (not shown). On the other hand, the ground wire of the piezoelectric element 1b is connected to the control circuit section and the like via the element housing section 1a, the metal tube 1f, and the holding section 1g. Note that two lead wires can be inserted into the metal tube 1f.

  In use, as shown in FIG. 1, the ultrasonic transceiver 1 is inserted into the mounting portion 4, and the holding portion 1g is sealed and fixed to the end of the mounting portion 4 using, for example, a screw. After that, the lead wire 1j is connected to the other terminal. After such preparation, the gas medium to be measured is caused to flow through the tube 2, and the ultrasonic beams B1 and B2 are transmitted and received through the propagation path W between the piezoelectric elements 1b to start the measurement.

  At this time, it is not possible to eliminate noise components leaking from the piezoelectric element 1b to the tube 2 via the element accommodating portion 1a, the metal tube 1f, and the holding portion 1g. However, since the metal tube 1f having a small cross-sectional area is used, and the metal tube 1f is bent to increase the length, the noise component is greatly attenuated, and the receiving piezoelectric element 1b passes through the gas. The SN ratio with the original measurement signal that has passed increases, and the flow rate measurement accuracy improves.

  FIG. 3 is a configuration diagram of the ultrasonic transceiver 1 according to the second embodiment, in which two spirally bent metal tubes 1f and 1f 'are used as a support mechanism. The same reference numerals as in the first embodiment denote the same members.

The metal tubes 1f and 1f 'have substantially the same shape and are arranged so as not to contact each other. In one embodiment, the lead wire 1j is inserted through the metal tube 1f. The ground wire may be transmitted using one of the metal tubes 1f and 1f ', but the lead wire 1j and the ground wire may be inserted through the metal tubes 1f and 1f', respectively.
In the case of the second embodiment, the diameter of each of the metal tubes 1f and 1f 'may be smaller than that of the first embodiment. For example, the outer diameter is 1.2 mm and the inner diameter is 0.5 mm.

  In the second embodiment, since the number of the metal tubes 1f and 1f 'is two, the element housing portion 1a can be held more firmly than in the first embodiment.

DESCRIPTION OF SYMBOLS 1 Ultrasonic transmitter / receiver 1a Element accommodating part 1b Piezoelectric element 1c Front wall 1f, 1f 'Metal tube 1g Holding part 1h Protective cylinder 1i Elastic filler 1j Lead wire 2 Tubular body 3 Tube wall 4 Attaching part

Claims (5)

  In an ultrasonic transmitter / receiver for an ultrasonic flowmeter for transmitting and receiving an ultrasonic beam in a fluid flowing through a tube, an element housing section in which a piezoelectric element for transmitting / receiving an ultrasonic beam to / from the fluid is disposed on a front wall. A holding portion for attaching to the tube, and a metal tube having a small cross-sectional area, one end of which is fixed to the element housing portion and the other end of which is fixed to the holding portion. An ultrasonic transmitter / receiver, characterized in that its length is increased.   The ultrasonic transceiver according to claim 1, wherein the metal tube is spirally bent.   The lead wire having one end connected to the piezoelectric element is inserted into the metal tube, and the other end of the lead wire is led out of the holding unit. Ultrasonic transceiver.   The ultrasonic transceiver according to any one of claims 1 to 3, wherein the number of the metal tubes is one or more.   The protection cylinder fixed to the holding part is spaced apart around the metal tube, and an elastic filler is filled in the protection cylinder. 2. The ultrasonic transceiver according to claim 1.

Images