JP2018173339A - Ultrasonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assemble an ultrasonic transceiving unit separately from a tube part, make it easy to attach the ultrasonic transceiving unit to the tube part, and make a piezoelectric element and its surrounding have a compact structure.SOLUTION: An inlet tube 12 and an outlet tube 13 are disposed in a so-called crank shape relative to a straight tube 11. On the straight tube 11, walls 12c and 13c in contact from the outside with a piezoelectric element are formed, and to the outside of the walls 12c and 13c, respective ultrasonic transceiving units 20 are detachably attached. The two ultrasonic transceiving units 20 have an identical shape and each include a synthetic resin cover part 21, a piezoelectric element provided in the cover part 21 for transmitting and receiving ultrasonic beams, and a cable part 23 connected to the piezoelectric element. A tube part 10 and the ultrasonic transceiving units 20 are separately assembled, and the ultrasonic transceiving units 20 are disposed at both ends of the tube part 10 and coupled with screws 31 and 32.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an ultrasonic flowmeter that is used in various industrial fields and measures a liquid flow rate in a pipe.

  In an ultrasonic flow meter, for example, piezoelectric elements that transmit and receive an ultrasonic beam are attached to both ends of a crank-type pipe section, and from one end to the other end of the pipe section through which fluid flows by these piezoelectric elements. The time during which the ultrasonic beam propagates from the other end to the other end is measured, and the flow velocity of the fluid flowing through the pipeline is measured from the difference in propagation time.

  The above-described crank-type pipe section is generally made of synthetic resin and requires a straight pipe section, an inlet pipe section, an outlet pipe section, and piezoelectric element attachment sections on both sides of the straight pipe section. Since this pipe section has a complicated structure, it cannot be molded by one injection molding, and is manufactured by dividing into several parts and combining them together.

  Patent Document 1 discloses such an ultrasonic flow meter. As shown in FIG. 5, the fluid to be measured passes through the inlet pipe 1, the straight pipe part 2, and the outlet pipe 3 in a crank shape, and is measured based on the propagation speed of the ultrasonic beam in the straight pipe part 2. The Piezoelectric elements 4a and 4b are attached to both sides of the straight pipe portion 2, and ultrasonic beams are transmitted and received by the piezoelectric elements 4a and 4b. The piezoelectric elements 4a and 4b are housed in cylindrical portions 5a and 5b formed integrally with the inlet pipe line 1 and the outlet pipe line 3, and are attached to the inner walls 6a and 6b on both sides of the straight pipe portion 2 to be piezoelectric. Lead wires 7a and 7b are connected to the elements 4a and 4b. In order to protect the piezoelectric elements 4a and 4b, cap nut-like covers 8a and 8b are screwed together from the outside of the cylindrical portions 5a and 5b.

  When the fluid to be measured is a corrosive fluid, the material of the inlet pipe 1, the straight pipe portion 2, and the outlet pipe 3 through which the fluid passes requires a corrosion-resistant resin. For example, fluororesin PTFE, PFA Must be used. Since the cylindrical portions 5a and 5b are integrally formed with the inlet pipe 1 and the outlet pipe 3, it is necessary to use a corrosion-resistant resin. Similarly, the covers 8a and 8b attached to the cylindrical portions 5a and 5b have a screw-in structure, and therefore, it is preferable to use the same material as the cylindrical portions 5a and 5b in consideration of an expansion coefficient and the like.

JP 2013-104838 A

  In the above-described conventional example, the cover 8a and 8b are structurally attached by screwing so as to surround the cylindrical portions 5a and 5b that accommodate the piezoelectric elements 4a and 4b, so that the volume of the cover 8 is increased. Furthermore, since the lead wires 7a and 7b are drawn out in the direction of the extension line of the straight pipe portion 2, there is a problem that the installation location of the ultrasonic flowmeter is limited.

  In addition, since ultrasonic flowmeters used in semiconductor manufacturing facilities handle corrosive fluids, it is necessary to use a corrosion-resistant resin in the pipeline, but the corrosion-resistant resin is commonly used, for example, polyethylene, polypropylene, etc. If the corrosion-resistant resin is used for the cylindrical portions 5a, 5b and the cover 8 which are expensive compared to the synthetic resin and do not come into contact with the liquid, the manufacturing cost becomes high.

  Further, the conventional ultrasonic flowmeter has a problem that the assembly work such as soldering of the lead wires 7a and 7b after the piezoelectric elements 4a and 4b are incorporated in the cylindrical portions 5a and 5b becomes complicated.

  The object of the present invention is to solve the above-mentioned problems and to assemble an ultrasonic transmission / reception unit separately from the pipe section, so that it is easy to mount on the pipe section, has a compact structure around the piezoelectric element, and is an inexpensive ultrasonic type. To provide a flow meter.

  In order to achieve the above object, an ultrasonic flowmeter according to the present invention includes a cover portion, a piezoelectric element that is disposed in the cover portion and transmits and receives an ultrasonic beam, and is connected to the piezoelectric element. An ultrasonic transmission / reception unit having a cable portion drawn out in the direction is detachably attached to both sides of a straight pipe line of a pipe line that allows fluid to flow into the crank type, and the pipe line extends from the transmission / reception surface of the piezoelectric element. An ultrasonic beam is transmitted and received in the unit, and a fluid flow rate is measured based on a propagation speed of the ultrasonic beam.

  According to the ultrasonic type flow meter of the present invention, a separate ultrasonic transmission / reception unit can be easily attached to the pipe line part, and it becomes compact, and further, the amount of expensive corrosion-resistant resin used is reduced.

It is a disassembled perspective view of the ultrasonic type flow meter of an Example. It is a perspective view of an ultrasonic flowmeter. It is sectional drawing of an ultrasonic flowmeter. It is a perspective view in the state where an ultrasonic transmission / reception unit is attached to a pipeline part. It is sectional drawing of the ultrasonic type flow meter of a prior art example.

The present invention will be described in detail based on the embodiment shown in FIGS.
1 is an exploded perspective view, FIG. 2 is a perspective view of an ultrasonic flow meter in an assembled state, and FIG. 3 is a cross-sectional view.

  The ultrasonic flow meter of the present embodiment is composed of a conduit portion 10 through which a fluid mainly flows and a pair of ultrasonic transmission / reception units 20 attached to both sides of the conduit portion 10.

  The pipe line part 10 is connected to the straight pipe line 11 and one end of the straight pipe line 11 in an L shape by heat welding or the like, and the inlet pipe line 12 into which the fluid flows into the straight pipe line 11 from a right angle direction. And an outlet pipe 13 that is coupled to the other end of the straight pipe 11 in an L shape and discharges fluid from the straight pipe 11 in a direction perpendicular to the straight pipe 11, and includes an inlet pipe 12, an outlet pipe Reference numeral 13 denotes a so-called crank shape with respect to the straight pipe line 11.

  The pipe section 10 is made of, for example, a corrosion-resistant resin such as fluororesin PTFE or PFA, and the straight pipe line 11, the inlet pipe line 12, and the outlet pipe line 13 that are individually manufactured by injection molding or the like are combined by heat welding or the like. ing. In addition, it becomes possible to confirm the flow of fluid visually by employ | adopting a transparent body for the pipe line part 10. FIG.

  The inlet pipe 12 and the outlet pipe 13 have an inner diameter of 4 mm, for example, and the straight pipe 11 also has an inner diameter of 4 mm. In addition, the internal diameter of the both ends of the straight pipe line 11 is expanded in a taper shape so that it may go to the main-body parts 12a and 13a of the inlet pipe line 12 and the outlet pipe line 13, and it is made not to produce flow-path resistance.

  The inlet pipe 12 and the outlet pipe 13 are made of the same member, and the main body portions 12a and 13a having a large internal volume, and the pipe body portions connected to the upstream side and the downstream side with respect to the main body portions 12a and 13a. 12b and 13b. In addition, fluid pipes are connected to the tips of the tube parts 12b and 13b, respectively.

  Walls 12c and 13c that contact the piezoelectric elements from the outside are formed facing the opposite sides of the main body portions 12a and 13a from the straight pipe path 11, and the piezoelectric elements are present outside these wall surfaces 12c and 13c. The ultrasonic transmission / reception units 20 are detachably mounted. A pair of screw insertion holes 12d and 13d and a pair of guide receiving portions 12e in which the guide pieces of the ultrasonic transmission / reception unit 20 are in contact with each other along the axial direction of the straight pipe path 11 on the outer peripheral portions of the main body portions 12a and 13a. , 13e are provided.

  The two ultrasonic transmission / reception units 20 have the same shape, a synthetic resin cover part 21, a piezoelectric element part 22 fixed in the cover part 21, and a part of the cover part 21 connected to the piezoelectric element part 22. And a cable part 23 drawn out to the outer flow rate calculation and measurement part.

  The cover portion 21 is molded from an inexpensive and hard synthetic resin material that is generally used. The cover portion 21 has a storage hole portion 21 a for fitting the piezoelectric element portion 22, and tips of two screws 31 and 32 inserted through the screw insertion holes 12 d and 12 d of the inlet conduit 12 and the outlet conduit 13. A pair of screw holes 21b to be screwed in is provided.

  In addition, when the cover portion 21 is attached to the inlet conduit 12 and the outlet conduit 13, a pair of guide pieces 21c having a guide function with respect to the guide receiving portions 12e and 13e are provided on the outer portion of the cover portion 21 and the main body portions 12a and 13a. It is provided for. A small hole 21d communicating with the storage hole 21a is formed in the outer end of the cover part 21.

  A piezoelectric element portion 22 is accommodated in the cover portion 21. The piezoelectric element portion 22 includes a piezoelectric element 22a that transmits and receives an ultrasonic beam, a holding portion 22b that fits and holds the piezoelectric element 22a and cannot rotate with respect to the housing hole portion 21a, and a piezoelectric element. Synthetic resin material adjusting screw that is screwed into the lead wire 22c connected to 22a and pulled out from the hole provided in the holding portion 22b and the screw hole provided in the center of the holding portion 22b, and presses and adjusts the piezoelectric element 22a 22d.

  The piezoelectric element 22a has a thin disc shape, and an acoustic matching plate 22e having the same shape is attached to the surface thereof. The piezoelectric element 22a is held by a holding portion 22b so that the acoustic matching plate 22e is exposed to the outside. ing. Note that an O-ring 22f is interposed between the main body portions 12a and 13a and the cover portion 21, and has a waterproof function for preventing water from entering between them.

  On the rear side of the cover portion 21, a cylindrical cable lead portion 21e extending in a direction perpendicular to the storage hole portion 21a is provided, and the lead wire 22c is soldered to the cable portion 23 in the storage hole portion 21a. The cable portion 23 is drawn to the outside through the cable lead portion 21e and can be connected to the flow rate calculation measurement portion. At that time, a waterproof bush 23a is inserted into the cable portion 23 so that water does not enter from the cable lead-out portion 21e. In the embodiment, the cable lead-out portion 21e is directed upward, but may be drawn downward.

  A support 33 can be attached to the straight pipe 11 to support the load of the ultrasonic flowmeter.

  When assembling, the pipe line part 10 and the ultrasonic transmission / reception unit 20 are assembled separately. In the ultrasonic transmission / reception unit 20, the cable part 23 drawn into the accommodation hole 21a is connected to the lead wire 22c, and then the piezoelectric element part 22 is inserted into the accommodation hole 21a from the open side of the cover part 21. Next, the piezoelectric element portion 22 configured to be hooked in front of the cover portion 21 is arranged so that the transmission / reception surfaces of the piezoelectric element 22a and the acoustic matching plate 22e are parallel to the wall surfaces 12c and 13c.

  The ultrasonic transmission / reception unit 20 assembled in this way is arranged on both sides of the pipe section 10 as shown in FIG. 4, and grease is transmitted so that the ultrasonic waves can be easily transmitted between the acoustic matching plate 22e and the wall surfaces 12c and 13c. And a waterproof O-ring 22f is interposed around the storage hole 21a of the cover portion 21. Further, the guide piece 21c is slid on the guide receiving portions 12e and 13e of the inlet pipe line 12 and the outlet pipe line 13 so that the cover part 21 is pushed into the main body parts 12a and 13a. Then, the screws 31 and 32 are inserted into the screw insertion holes 12d and 13d, respectively, and the screws 31 and 32 are screwed and fixed into the screw holes 21b, so that the ultrasonic transmission / reception unit 20 is connected to both sides of the duct portion 10. Integrated.

  Next, the output of the piezoelectric element 22a is adjusted. The ends of the two cable parts 23 are connected to the flow rate calculation and measurement part, and while obtaining the output of the piezoelectric element 22a, a screwdriver is inserted through the small hole 21d of the cover part 21, and the adjustment screw 22d is rotated with respect to the holding part 22b. . The adjustment screw 22d presses the piezoelectric element 22a to change the degree of adhesion of the transmission / reception surface to the wall surfaces 12c and 13c, whereby the output from the piezoelectric element 22a is adjusted to a predetermined size or the like.

  At this time, if necessary, a liquid having a reference flow rate is actually allowed to flow through the conduit portion 10, and an ultrasonic beam is transmitted / received from the piezoelectric element 22a into the straight conduit 11 to output the piezoelectric element 22a with respect to the flow rate. Can be calibrated.

  When this adjustment is completed, silicon resin 21f and the like are filled into the storage hole 21a from the small hole 21d of the cover part 21 and cured. As a result, the tightening amount of the adjusting screw 22d is fixed, water is prevented from entering the storage hole 21a, and electrical insulation in the storage hole 21a can be ensured.

  The ultrasonic flow meter assembled in this manner allows a fluid to be measured to flow through the pipe section 10, and is transmitted and received between the wall surfaces 12c and 13c by the pair of piezoelectric elements 22a by the flow measurement calculation section connected to the piezoelectric elements 22a. The propagation speed of the ultrasonic beam can be measured, and the flow velocity of the fluid in the straight pipe 11, that is, the fluid flow rate can be measured.

  In the present embodiment, the ultrasonic transmission / reception unit 20 is attached to the pipe line portion 10, so that it is smaller than the ultrasonic flow meter in which the piezoelectric element is integrated as in the conventional example, and the cable is also on the side. It can be pulled out toward the direction and is easy to assemble. In addition, a piezoelectric element having a diameter larger than that of the conventional example can be used, and the accuracy is further improved by increasing the power of the piezoelectric element.

  Moreover, since the cover part 21 of the ultrasonic transmission / reception unit 20 can use a synthetic resin material cheaper than the pipe line part 10, it becomes possible to manufacture an ultrasonic flowmeter more inexpensively.

  When the ultrasonic transmission / reception unit 20 breaks down, the screws 31 and 32 can be removed, the ultrasonic transmission / reception unit 20 can be removed from the duct portion 10, and replaced with a new ultrasonic transmission / reception unit 20.

DESCRIPTION OF SYMBOLS 10 Pipe part 11 Straight pipe 12 Inlet pipe 12a, 13a Body part 12b, 13b Tube part 12c, 13c Wall surface 13 Outlet pipe 20 Ultrasonic transmission / reception unit 21 Cover part 21a Storage hole part 21d Small hole 21f Silicone resin 22 Piezoelectric element 22a Piezoelectric element 22b Holding part 22c Lead wire 22d Adjustment screw 23 Cable part 31, 32 Screw

Claims (4)

  An ultrasonic transmission / reception unit comprising: a cover part; a piezoelectric element disposed in the cover part for transmitting and receiving an ultrasonic beam; and a cable part connected to the piezoelectric element and drawn outward from the cover part. Based on the propagation speed of the ultrasonic beam, the ultrasonic beam is transmitted / received from the transmission / reception surface of the piezoelectric element into the pipe portion. An ultrasonic flowmeter for measuring a fluid flow rate.   2. The ultrasonic wave according to claim 1, wherein the ultrasonic transmission / reception unit is attached to the pipe line portion with a transmission / reception surface of the piezoelectric element in close contact with an outer wall surface facing each other on both sides of the straight pipe line. Type flow meter.   The ultrasonic wave according to claim 1 or 2, wherein a guide piece having a guide function with respect to the pipe line part is provided on the cover part of the ultrasonic wave transmitting / receiving unit. Type flow meter.   The ultrasonic flowmeter according to any one of claims 1 to 3, wherein the ultrasonic transmission / reception unit is connected to the pipe line portion by a screw.

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