JP2017116444A - Clamp-on type ultrasonic flow meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clam-on type ultrasonic flow meter high in versatility not depending on a shape of piping when mounted on the piping.SOLUTION: A clamp-on type ultrasonic flow meter 1 is constituted so as to mount ultrasonic transceivers 10, 20 on the outer peripheral surface of piping 100 via a mount 30. A bottom face 31 of a mount 100 has a shape recessed along a longitudinal direction, and outer edges 31a, 31b only which extend in the longitudinal direction so as to contact with the outer peripheral surface of the piping 110. According to this flow meter 1, since the bottom face 31 of the mount 30 has a shape recessed in an inverted V-shape, the outer edges 31a, 31b only which extend in the longitudinal direction are grounded when mounted on the outer peripheral surface of the piping 110, and as a result, the mount 30 can be stably mounted even for the piping 100 having any curvature without causing rattling.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a clamp-on type ultrasonic flowmeter that is attached to the outside of a pipe by a clamp method and measures the flow rate of a fluid that moves inside the pipe.

  The clamp-on type ultrasonic flowmeter is a flowmeter that is attached to a part of the outer peripheral surface of a pipe and measures the flow rate of a fluid that moves inside the pipe from the outside of the pipe. The clamp-on type ultrasonic flowmeter can be mainly classified into a propagation time difference type and a Doppler type. The propagation time difference formula is based on the difference in time required for the ultrasonic wave to travel in the forward and return paths by reciprocating the ultrasonic wave in a path that crosses the fluid moving inside the pipe diagonally. Is a method of measuring. On the other hand, the Doppler method is a method of measuring the flow rate of fluid from the moving speed of suspended particles, etc., assuming that suspended particles and bubbles contained in the fluid move at the same speed as the fluid. The moving speed of the suspended particles or the like is measured by detecting the frequency of the ultrasonic waves by transmitting ultrasonic waves into the fluid and changing the frequency of the ultrasonic waves reflected by the suspended particles or the like due to the Doppler effect.

  Then, what is shown to patent document 1 is known as a structure which attaches a clamp-on type ultrasonic flowmeter to piping. This mounting structure is configured such that a mounting base is fixed to the outer peripheral surface of the pipe with a belt, and a detector is mounted on the mounting base. The bottom surface of the mounting base that is in contact with the outer peripheral surface of the pipe is formed with the same curvature as that of the outer peripheral surface of the pipe, so that displacement is less likely to occur when the mounting base is fixed to the pipe. Can be expected.

JP 61-61422 A

  However, the conventional clamp-on type ultrasonic flowmeter has a problem that a mounting base for mounting a detector cannot be stably fixed to pipes having different curvatures on the outer peripheral surface.

  The present invention was created in view of the above problems, and an object of the present invention is to provide a versatile clamp-on type ultrasonic flowmeter that does not depend on the shape of the pipe when attached to the pipe.

  In the clamp-on type ultrasonic flowmeter configured to attach the ultrasonic transmitter / receiver to the outer peripheral surface of the pipe via the mounting base, the bottom surface of the mounting base has a concave shape along the longitudinal direction and is According to the clamp-on type ultrasonic flowmeter configured such that only the outer edge extending in the direction contacts the outer peripheral surface of the pipe.

  According to the clamp-on type ultrasonic flowmeter of the present invention, the bottom surface of the mounting base for mounting the ultrasonic transceiver has a concave shape along the longitudinal direction, and only the outer edge extending in the longitudinal direction is the pipe. Since it is configured to contact the outer peripheral surface, the ultrasonic transmitter / receiver can be attached stably regardless of the curvature of the outer peripheral surface of the pipe, so the clamp has high flow rate detection accuracy and excellent versatility. An on-type ultrasonic flow meter can be provided.

It is a perspective view which shows the structure of the clamp-on type ultrasonic flowmeter which is this invention. It is a front view which shows the structure of the clamp-on type ultrasonic flowmeter which is this invention. It is a top view which shows the structure of the clamp-on type ultrasonic flowmeter which is this invention. It is a left view which shows the structure of the clamp-on type ultrasonic flowmeter which is this invention. It is a figure explaining the propagation path of the ultrasonic wave in piping.

  Hereinafter, embodiments of a clamp-on type ultrasonic flowmeter of the present invention will be described with reference to the drawings. A clamp-on type ultrasonic flowmeter 1 of the present invention shown in FIG. 1 includes ultrasonic transceivers 10 and 20 and a mounting base 30.

  The ultrasonic transceivers 10 and 20 are attached to the pipe 100 via a metal mounting base 30. As shown in FIGS. 2 and 3, the mounting base 30 is fixed to the pipe 100 by winding the belt 40, and guides the bottom face 31 grounded to the outer peripheral surface of the pipe 100 and the ultrasonic transceivers 10 and 20. And a side surface 32. As shown in FIG. 4, the bottom surface 31 of the mounting base 30 has an inverted V shape in a longitudinal sectional view. In other words, the bottom surface 31 has a concave shape along the longitudinal direction and extends in the longitudinal direction. Only the outer edges 31 a and 31 b are formed so as to contact the outer peripheral surface of the pipe 100. Further, a cutout portion 32 a is formed on the side surface 32 of the mounting base 30, while the magnets 11 and 21 are provided on the side surfaces of the ultrasonic transceivers 10 and 20. Is inserted from above the mounting base 30, the magnets 11, 21 and the notch 32 a are engaged, and the ultrasonic transceivers 10, 20 are attached to the mounting base 30 by winding the belts 50, 60 in this state. Is done.

  As a material for forming the ultrasonic transceivers 10 and 20, a material having an appropriate sound wave propagation speed is selected in consideration of the sound wave propagation speed of the material forming the pipe 100. Further, the ultrasonic transceivers 10 and 20 are provided with electrodes (not shown) and lead wires (not shown) for applying a voltage to the built-in ultrasonic transducers 10a and 20a.

  On the bottom surface 31 of the mounting base 30, openings 33 and 34 are formed by hollowing out a range facing the bottom surfaces of the ultrasonic transceivers 10 and 20. In addition, when air (gap) exists between the bottom surfaces of the ultrasonic transceivers 10 and 20 and the outer peripheral surface of the pipe 100, since the acoustic impedance of air is small, the ultrasonic wave is an interface between the outer peripheral surface of the pipe 100 and the air. The contact medium 110 is preferably filled in the gap between the ultrasonic transceivers 10 and 20 and the pipe 100. By applying the contact medium 110 on the outer peripheral surface of the pipe 100 and then pressing the ultrasonic transceivers 10 and 20 against the pipe 100, the gap 110 can be filled with the contact medium 110. As the contact medium 110 used to exclude air from the ultrasonic wave propagation path, a known material can be used. As the contact medium 110, a liquid or paste-like material in which bubbles do not easily remain is used. Generally, water, oil, water glass, grease, petroleum jelly, or the like is used.

  Each of the ultrasonic transducers 10a and 20a of the ultrasonic transceivers 10 and 20 applies (transmits) ultrasonic waves to the inside of the ultrasonic receiver when a voltage is applied to the electrodes, and conversely, applies ultrasonic waves ( When received, a voltage is generated at the electrode. Therefore, each of the ultrasonic transceivers 10 and 20 provided with the ultrasonic transducers 10 a and 20 a is both an ultrasonic transmitter 10 and a receiver 20. The ultrasonic transceivers 10 and 20 are disposed on the outer peripheral surface of the pipe 100 so as to transmit and receive ultrasonic waves obliquely with respect to the moving direction of the fluid moving inside the pipe 100. The alternate long and short dash line in FIG. 5 means an example of an ultrasonic wave propagation path.

  The flow rate of the fluid 120 moving inside the pipe 100 is measured as follows. First, a voltage pulse is applied to the ultrasonic transducer 10a of the ultrasonic transmitter / receiver 10 to transmit ultrasonic waves. The ultrasonic wave propagates in the order of the inside of the ultrasonic transmitter / receiver 10, the pipe 100, the fluid 120, the pipe 100, and the ultrasonic transmitter / receiver 20 in the order of the dashed line shown in FIG. 5. Is received by the ultrasonic transducer 20a and a voltage signal is output. A time (T1) from when the ultrasonic transmitter / receiver 10 starts transmitting ultrasonic waves until the ultrasonic transmitter / receiver 20 receives ultrasonic waves is detected. Next, a voltage pulse is applied to the ultrasonic transducer 20 a of the ultrasonic transmitter / receiver 20 to propagate the ultrasonic wave through the reverse propagation path, and the ultrasonic wave is transmitted by the ultrasonic transducer 10 a of the ultrasonic transmitter / receiver 10. Receive. The time (T2) from when the ultrasonic transmitter / receiver 20 starts transmitting ultrasonic waves until the ultrasonic transmitter / receiver 10 receives ultrasonic waves is detected.

  The time required for the ultrasonic wave to propagate between the ultrasonic transceivers 10 and 20 (T1 and T2) differs depending on the direction of propagation of the ultrasonic wave (the direction indicated by arrows A and B in FIG. 5). Become. Since the ultrasonic wave that travels from the ultrasonic transceiver 10 to the ultrasonic transceiver 20 (in the direction indicated by the arrow A) travels in the fluid 120 and travels in the fluid, the propagation time (T1) is determined by the fluid 120. The value is shorter than when it is stationary. On the other hand, since the ultrasonic wave directed from the ultrasonic transmitter / receiver 20 to the ultrasonic transmitter / receiver 10 (in the direction indicated by the arrow B) propagates in the fluid against the flow of the fluid 120, the propagation time (T 2) is the fluid 120. This is a long value compared to when the is stationary. The difference in propagation time (T2-T1) is correlated with the moving speed of the fluid 120, and the moving speed of the fluid 120 is calculated from the difference in propagation time. Then, the flow rate of the fluid 120 can be calculated from the moving speed of the obtained fluid 120, the flowing water cross-sectional area of the pipe 100, and the like.

  According to the clamp-on type ultrasonic flowmeter 1, the bottom surface 31 of the mounting base 30 has a concave shape in an inverted V shape, so that the outer edge extending in the longitudinal direction when mounted on the outer peripheral surface of the pipe 110. Only 31a and 31b are grounded. For this reason, since the mounting base 30 is stably attached to the pipe 100 having any curvature without wobbling, the detection accuracy of the flow rate by the ultrasonic transceivers 10 and 20 is improved.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Clamp-on type ultrasonic flowmeter 10, 20 Ultrasonic transmitter / receiver 30 Mounting base 100 Piping 110 Contact medium

Claims (1)

In the clamp-on type ultrasonic flowmeter configured to attach the ultrasonic transceiver to the outer peripheral surface of the pipe via the mounting base,
A clamp-on type ultrasonic flowmeter, wherein the bottom surface of the mounting base has a shape that is recessed along the longitudinal direction, and only the outer edge extending in the longitudinal direction is in contact with the outer peripheral surface of the pipe.

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