JP2008275556A - Ultrasonic flow meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an ultrasonic reflecting surface to be arranged simply in fluid, in order to realize good measurement precision. <P>SOLUTION: Two bars 12 are inserted into a flow channel tube 11 in a direction perpendicular to the tube axis. Heads of the bars 12 are obliquely cut out at 45 degrees, and these tilted reflecting surfaces 13 are disposed so as to face opposite directions mutually. Furthermore, flat surfaces 14 are formed so as to face each other at the heads of the bars 12. Ultrasonic transducers 16 are attached to outer edges of the bars 12 positioned on the outside of the tube 11, respectively. Ultrasonic beams B are transmitted and received by the two ultrasonic transducers 16 alternately and repeatedly. The ultrasonic beam B transmitted by the upstream-side ultrasonic transducer 16a is projected into the fluid through the bar 12a, the tilted reflecting surface 13a and the flat surface 14a, propagates through a prescribed distance between the flat surfaces 14 and reaches the downstream-side ultrasonic transducer 16b after passing through the flat surface 14b, the tilted reflecting surface 13b and the bar 12b. The ultrasonic beam B transmitted by the ultrasonic transducer 16b reaches the ultrasonic transducer 16a after passing through the reverse path. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic flowmeter provided with an ultrasonic reflection surface in a fluid in a tubular body.

  Conventionally, in a time difference type ultrasonic flowmeter, ultrasonic transducers 2 and 3 are generally installed at upstream and downstream positions along the flow outside the tube 1 as shown in FIG. The ultrasonic beam B is transmitted and received alternately between the ultrasonic transducers 2 and 3, and the propagation of the ultrasonic beam B reflected from the inner wall of the tubular body 1 from the upstream side to the downstream side, and the downstream side From the time difference caused by the propagation of the same ultrasonic beam B from the upstream side to the upstream side, the flow velocity and flow rate of the fluid flowing in the tube body 1 are obtained.

  However, refraction occurs when the ultrasonic beam B travels from the tube 1 into the liquid and from the fluid into the tube 1. Furthermore, the refraction at this time causes a change in the refraction angle due to the kinematic viscosity such as the density, viscosity, temperature, etc. of the liquid, resulting in a measurement failure.

  For example, when the fluid is water, for example, when the temperature is 1 ° C. and 99 ° C., the kinematic viscosity is greatly different and the refraction angle changes, and a sufficient signal can be obtained unless the positions of the ultrasonic transducers 2 and 3 are moved. I can't.

  Therefore, as shown in FIG. 10, if the ultrasonic transducers 2 and 3 are connected with a straight line with an angle, this point can be solved, but the tubular body 1 is accurately processed obliquely, It is extremely difficult to take waterproof measures.

  As one measure for dealing with such a problem, the means of Patent Document 1 is known. According to this Patent Document 1, as shown in FIG. 11, a pair of metal reflectors 5 and 6 are suspended in a tubular body 4, and an ultrasonic beam B generated from an ultrasonic transducer 7 is suspended from the tubular body 4. It is introduced into the interior, reflected by the reflector 5 and directed in the tube axis direction, received again by the counterpart reflector 6 and guided to the counterpart ultrasonic transducer 8. The ultrasonic beam B generated by the ultrasonic transducer 8 also reaches the ultrasonic transducer 7 via the reverse path.

JP-T-2004-526127

  However, in the above-mentioned Patent Document 1, since the ultrasonic beam B enters the tube 1 at a right angle, there is no refraction angle between the tube 1 and the fluid, but there are the following problems. .

(1) In the ultrasonic wave propagation path between the tube body 1 and the reflector 5, and between the tube body 1 and the reflector 6, the ultrasonic beam B is deflected by the flow velocity of the fluid, and the ultrasonic beam B is efficiently transmitted to the other side. The ultrasonic transducers 7 and 8 are not reached, the S / N becomes large, and an error is likely to intervene.
(2) The reflectors 5 and 6 suspended in the tube body 1 are easy to move, and the transmission distance of the ultrasonic beam B is likely to change.
(3) It is not easy to attach the reflectors 5 and 6 to the tube body 1.

  An object of the present invention is to provide an ultrasonic flowmeter that solves the above-described problems and that can easily arrange an ultrasonic reflection surface in a fluid and that can obtain good measurement accuracy.

  In order to achieve the above object, the technical feature of the ultrasonic flowmeter according to the present invention is that an ultrasonic flowmeter for measuring a flow rate of a fluid flowing through a flow path tube body is used for a pair of ultrasonic wave propagation in the tube body. Are inserted in a direction perpendicular to the tube axis direction at intervals in the tube axis direction, and inclined reflecting surfaces are respectively provided on the opposite sides of the ends of the rod bodies in the tube body to the opposite sides of the rod bodies. And an ultrasonic transducer is attached to each outer end of the rod-shaped body outside the tubular body, and the ultrasonic beam is alternately transmitted and received by the ultrasonic transducer, and the ultrasonic beam is It is to be transmitted from the one rod-like body and the inclined reflection surface to the ultrasonic transducer on the other side via the fluid, the other-side inclined reflection surface and the other-side rod-like body.

  According to the ultrasonic flowmeter of the present invention, it is easy to mount and the flow rate can be accurately measured.

The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 shows a configuration diagram of an ultrasonic flowmeter according to the embodiment. For example, a flow tube 11 having an inner diameter of 20 mm is made of a synthetic resin material such as PPS and has a diameter of 7 mm for ultrasonic beam propagation. Two rod-like bodies 12a and 12b having a round bar shape are inserted with their tips at a position about 1/3 of the tube diameter. The insertion direction of the rod-shaped bodies 12a and 12b is inserted toward the tube axis O in a plane orthogonal to the tube axis O, and the interval between the rod-shaped bodies 12a and 12b in the tube axis direction is, for example, 80 mm.

  As shown in FIGS. 2 and 3, inclined reflecting surfaces 13 a and 13 b cut at an angle of 45 degrees are formed on the opposite sides of the ends of the rod-like bodies 12 a and 12 b, and these inclined reflecting surfaces 13 a and 13 b are formed. Are oriented in opposite directions. Furthermore, flat surfaces 14a and 14b orthogonal to the tube axis direction are formed at the tips of the rod-shaped bodies 12a and 12b so as to face each other. The flat surfaces 14a and 14b are cut into a flat shape through a smooth curved surface from an intermediate portion of the rod-like bodies 12a and 12b so that no step is generated in the rod-like bodies 12a and 12b.

  Ultrasonic transducers 16a and 16b are respectively attached to the outer ends 15a and 15b of the rod-shaped bodies 12a and 12b located outside the tubular body 11, and these ultrasonic transducers 16a and 16b are not shown. An ultrasonic transmission circuit is connected, the outputs of the ultrasonic transducers 16 a and 16 b are connected to the calculation control means 17, and the output of the calculation control means 17 is connected to the display means 18.

  When measuring the flow rate, the ultrasonic transducers 16a and 16b repeatedly transmit and receive the ultrasonic beam B alternately. The ultrasonic beam B transmitted from the upstream ultrasonic transducer 16a propagates through the rod-like body 12a, is reflected in the tube axis direction by the inclined reflecting surface 13a at the tip, and is emitted into the fluid through the flat surface 14a. . The ultrasonic beam passes through the fluid of a predetermined distance between the flat surfaces 14a and 14b, travels through the rod-like body 12b via the mating flat surface 14b and the inclined reflecting surface 13b, and reaches the ultrasonic transducer 16b on the downstream side. The ultrasonic beam B from the downstream ultrasonic transducer 16b reaches the upstream ultrasonic transducer 16a through the reverse path.

  When the ultrasonic beam B passes between the flat surfaces 14a and 14b of the rod-like bodies 12a and 12b, it is affected by the flow velocity, and it takes time to reach the downstream side from the upstream side and time to reach the upstream side from the downstream side. Are different, and the propagation time difference is measured by the arithmetic control means 17. Based on this propagation time difference, the calculation control means 17 calculates the flow rate value by a known method and displays it on the display means 18 or outputs it to another circuit.

  As described above, in this embodiment, the incidence of the ultrasonic beam B into the tubular body is transmitted to the rod-shaped bodies 12a and 12b, so that there is no influence of refraction or fluid flow velocity between the rod-shaped bodies 12a and 12b. Therefore, accurate measurement is possible. Further, the rod-like bodies 12a and 12b can be attached to the tube body 11 simply by perforating holes in the tube body 11 in the direction perpendicular to the tube axis O.

  In the above-described embodiment, the flat surfaces 14a and 14b are formed on the rod-like bodies 12a and 12b having a circular cross section, and it is necessary to form curved surfaces and inclined surfaces, and the ultrasonic beam B is irregularly reflected by these curved surfaces and the like. It is conceivable that the noise component becomes large.

  As a countermeasure against this, as shown in FIG. 4, the rod-shaped bodies 12a and 12b may have a rectangular cross section. In this case, the above-mentioned problem of noise generation is solved, and the area of the inclined reflecting surfaces 13a and 13b can be increased, but it becomes a resistance to the fluid and the flow is greatly disturbed.

  Therefore, as shown in FIG. 5 or FIG. 6, a rod-shaped body 12 having a semicircular, semi-elliptical or triangular shape is used, and the flat surface 14 is preliminarily made of a material. It is preferable that the upstream surface and the downstream surface of the rod-shaped body 12b be circular, elliptical, or triangular because the flow is not greatly disturbed.

  Furthermore, the flat surfaces 14a and 14b at the tips of the rod-shaped bodies 12a and 12b can be processed into spherical surfaces to have a lens effect. Thereby, the ultrasonic beam B in the process of reaching the spherical surfaces of the counterpart rod-like bodies 12a and 12b can be converged into an arbitrary shape, and efficient propagation can be performed. Moreover, you may give the lens effect by making the inclined reflective surfaces 13a and 13b into a curved surface.

  Furthermore, it is desirable not to insert the rod-like bodies 12a and 12b into the tube body 11 in consideration of laminar flow because of fluid resistance. Further, the insertion direction is not necessarily directed to the tube axis O, and may be eccentric with respect to the tube axis O as shown in FIG.

  Further, the rod-like bodies 12a and 12b are not aligned parallel to each other when viewed from the tube axis direction, and even if the insertion direction into the tube body 11 is different as shown in FIG. If they match, there is no problem.

  The material of the rod-like bodies 12a and 12b is not necessarily a synthetic resin, and may be a metal.

It is a block diagram of an Example. It is a front view of a rod-shaped body. It is a rear view of a rod-shaped body. It is a perspective view of the modification of a rod-shaped body. It is sectional drawing of the modification of a rod-shaped body. It is sectional drawing of the modification of a rod-shaped body. It is explanatory drawing of the insertion direction of a rod-shaped body. It is explanatory drawing of the insertion direction of a rod-shaped body. It is a block diagram of a prior art example. It is a block diagram of a prior art example. It is a block diagram of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Tube body 12a, 12b Rod-shaped body 13a, 13b Inclined reflection surface 14a, 14b Plane 15a, 15b Outer end part 16a, 16b Ultrasonic transducer 17 Calculation control means 18 Display means

Claims (4)

  In the ultrasonic flowmeter for measuring the flow rate of the fluid flowing through the flow path tube body, a pair of ultrasonic propagation rods in the tube body are spaced in the tube axis direction and perpendicular to the tube axis direction. Inserted into the tube, and formed with an inclined reflecting surface on the opposite side of the ends of the rods facing each other at the ends of the rods, and transmitting and receiving ultrasonic waves to the outer ends of the rods outside the tube. Attach a wave device, and alternately repeat transmission and reception of an ultrasonic beam by the ultrasonic transducer, and the ultrasonic beam is transmitted from the one rod-shaped body, the inclined reflection surface, the fluid, the counterpart inclined reflection surface, An ultrasonic flowmeter, wherein the ultrasonic flowmeter is transmitted to the ultrasonic transducer on the other side via a counterpart rod-like body.   2. The ultrasonic wave according to claim 1, wherein a portion of the rod-like body that is reflected by the inclined reflecting surface and the ultrasonic beam enters and exits the fluid is formed in a planar shape perpendicular to the tube axis. Flowmeter.   2. The ultrasonic flowmeter according to claim 1, wherein a portion of the rod-like body that is reflected by the inclined reflecting surface and the ultrasonic beam enters and exits the fluid is formed in a spherical shape.   The ultrasonic flowmeter according to claim 1, wherein the rod-shaped body is inserted toward a tube axis.

Images