Clamp-on mechanism for ultrasonic flowmeters

Abstract

A suitable pressure force is applied stably to the measuring tube, preventing plastic deformation of the measuring tube and enabling an ultrasonic signal with good accuracy to be obtained. [Solution] The clamp-on mechanism 1 is composed of a main body 2 that transmits various data to the outside, and a lid 3 that is openably and closably connected to the main body 2. The main body 2 is provided with two pedestals 2b in the longitudinal direction for placing a measurement tube P on it. The front and rear pedestals 2b are composed of an acoustic matching layer 2e that is disposed between the piezoelectric vibrator 2d and transmits ultrasonic waves, and a thin protective film 2f that covers the upper side of the acoustic matching layer 2e. The lid 3 is provided with a pressing piece 3b that presses the measurement tube P on the pedestal 2b from above with the repulsive force of an elastic body 3i. When the lid 3 is closed on the main body 2, the measurement tube P, which has a circular cross section, is pressed from above and below by the pressing piece 3b and the base 2b, and the measurement tube P is expanded in the width direction and deformed into an approximately elliptical shape.

Description

[Technical Field]

[0001] The present invention relates to a clamp-on mechanism for an ultrasonic flow meter that fixes a fluid measuring unit to an existing measuring pipe made of synthetic resin after installation. [Background technology]

[0002] Patent Document 1 discloses a clamp-on ultrasonic flowmeter in which a piezoelectric vibrator generates guided waves by ultrasonic waves that propagate in the axial direction using a measuring pipe through which a fluid flows as a medium.

[0003] In such clamp-on ultrasonic flowmeters that propagate guided waves through a measuring pipe, when the fluid measuring unit is fixed around an existing measuring pipe, the ultrasonic transmission parts must be tightly attached to the measuring pipe in order to efficiently transmit the ultrasonic waves. Therefore, the adhesion is improved by sandwiching a soft material such as synthetic rubber or grease between the ultrasonic transmission parts and the measuring pipe.

[0004] When the fluid measuring unit is clamped onto the measuring pipe, synthetic rubber or the like is inserted as a material to fill the gap between the ultrasonic transmission part and the measuring pipe in order to improve the transmission characteristics of the ultrasonic waves to the measuring pipe. In such a case, however, in order to transmit a guided wave of sufficient magnitude to the measuring pipe, it is necessary to increase the pressing force of the synthetic rubber against the measuring pipe. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6106338 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the pressure applied from the fluid measuring unit to the measuring tube from the outside is increased and the pressure applied to the measuring tube made of synthetic resin is greater than the force that causes plastic deformation, the measuring tube will remain deformed and will have difficulty returning to its original shape, the cross-sectional area of ​​the measuring tube will be prone to change, and furthermore, pressure loss will increase and breakage or scratches may occur.

[0007] Furthermore, the pressing force applied by the fluid measuring unit to the measuring tube is generated by a reaction force caused by deformation of each component constituting the clamp-on mechanism of the flowmeter when clamped, but there is a problem in that this force varies depending on each component and the assembly operation.

[0008] An object of the present invention is to solve the above-mentioned problems and to provide a clamp-on mechanism for an ultrasonic flowmeter that applies a moderate and stable pressing force to the measuring tube, prevents plastic deformation of the measuring tube made of synthetic resin, and obtains highly accurate ultrasonic signals. [Means for solving the problem]

[0009] In order to achieve the above object, the clamp-on mechanism according to the present invention comprises: a holding portion that clamps and holds a straight measuring tube; Two measuring pipes are provided in the longitudinal direction of the measuring pipe. In a clamp-on mechanism of an ultrasonic flow meter, the clamp-on mechanism includes an ultrasonic transmitter / receiver unit having a pair of piezoelectric vibrators for transmitting and receiving ultrasonic waves, the holding unit comprising: provided corresponding to the pair of piezoelectric vibrators, Place the measuring tube a pair The elastic force of the base and the elastic body a pair The measuring tube on the base is pressed from above. a pair A pressing piece; a pair The base portion and a pair Between the pressing piece It is established, When the measuring tube is pressed from above and below, the measuring tube moves to expand in the width direction. From both sides of the measuring tube Regulate two a pair of side walls; Each of the two pairs of side wall portions The contact surface of the side wall portion with the measuring tube is an inclined surface that is inclined so that the upper part protrudes inward, and the contact point of the contact surface with the measuring tube is slightly above the widest point of the measuring tube in the width direction. In order to achieve the above object, the clamp-on mechanism according to the present invention comprises: a holding portion that clamps and holds a straight measuring tube; Two measuring pipes are provided in the longitudinal direction of the measuring pipe. In a clamp-on mechanism of an ultrasonic flow meter, the clamp-on mechanism includes an ultrasonic transmitter / receiver unit having a pair of piezoelectric vibrators for transmitting and receiving ultrasonic waves, the holding unit comprising: provided corresponding to the pair of piezoelectric vibrators, Place the measuring tube a pair The elastic force of the base and the elastic body a pair The measuring tube on the base is pressed from above. a pair A pressing piece; a pair The base portion and a pair Between the pressing piece It is established, When the measuring tube is pressed from above and below, the measuring tube moves to expand in the width direction. From both sides of the measuring tube Regulate two a pair of side walls; Each of the two pairs of side wall portions The side wall portion is characterized in that a plurality of uneven portions are provided along the direction of the central axis of the measuring pipe. [Effects of the Invention]

[0010] The clamp-on mechanism of the ultrasonic flowmeter according to the present invention allows the fluid measuring unit to be attached with an appropriate pressing force while preventing plastic deformation of the measuring tube. Furthermore, an elastic structure using a spring or the like is used to apply pressure from above, which absorbs variations in the dimensional accuracy of the product and applies a stable pressing force, improving the measurement accuracy of the flowmeter and extending the life of the measuring tube. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 10 is a perspective view of the clamp-on mechanism attached to the measuring pipe. [Figure 2] FIG. 10 is a perspective view of the clamp-on mechanism with the measuring tube placed on the base and the lid open. [Figure 3] FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along the line AA′ in FIG. [Figure 5] FIG. 2 is a cross-sectional view taken along the line BB′ in FIG. [Figure 6]FIG. 10 is a cross-sectional view of a state in which the measuring pipe is pressed by a pressing piece. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail based on the illustrated embodiment. FIG. 1 is a perspective view of the clamp-on mechanism attached to a synthetic resin measuring tube, FIG. 2 is a perspective view of the mechanism in the state shown in FIG. 1 with the lid opened, and FIG. 3 is a perspective view of the main body.

[0013] The clamp-on mechanism 1, which is a roughly rectangular parallelepiped, is composed of a main body 2 on which the measurement pipe P is placed and to which a connection cable can be connected at the bottom, and a lid 3 which is openably and closably connected to the main body 2 via a connecting part 2a. Inside the main body 2, there are provided base parts 2b, which are provided at two positions in the longitudinal direction and have an arc-shaped saucer-like cross section and on which the measurement pipe P is placed, and side walls 2c, which are provided on both sides of the base part 2b and which restrict movement of the measurement pipe P in the width direction.

[0014] Figure 4 is a cross-sectional view taken along line A-A' in Figure 1, and Figure 5 is a cross-sectional view taken along line B-B' in Figure 1. The front and rear base portions 2b in the longitudinal direction are arranged between the piezoelectric vibrator 2d, which is the transmitting and receiving element, and are composed of an acoustic matching layer 2e that transmits ultrasonic waves and a thin protective film portion 2f that covers the upper side of the acoustic matching layer 2e. This acoustic matching layer 2e is fixed to the main body portion 2 from below with fixing screws 2g, making the base portion 2b immobile.

[0015] The acoustic matching layer 2e, made of a synthetic resin material or the like, improves the ultrasonic wave incident / reflection characteristics with the piezoelectric vibrator 2d, and the piezoelectric vibrator 2d is disposed at one end of the acoustic matching layer 2e. The acoustic matching layer 2e is shaped to enable efficient transmission of ultrasonic guide waves between the piezoelectric vibrator 2d and the measuring pipe P.

[0016] The protective film portion 2f, which is made of a thin, waterproof rubber sheet material or the like, has an arc-shaped cross section following the upper surface of the acoustic matching layer 2e in order to tightly fit the lower part of the measuring tube P as shown in FIG.

[0017] The fluid measuring unit 2h is connected to a pair of piezoelectric vibrators 2d that emit and receive ultrasonic waves that serve as guide waves. These piezoelectric vibrators 2d are symmetrically arranged facing each other diagonally upward via acoustic matching layers 2e that are placed at two positions in the longitudinal direction.

[0018] In addition, the side wall portions 2c on both sides of the base portion 2b serve to restrict the movement of the measurement tube P in the width direction when the measurement tube P is placed on the base portion 2b, but are positioned so as not to obstruct the propagation of ultrasonic waves.

[0019] The contact surface 2l of the side wall 2c with the measurement pipe P is located at a position where it contacts approximately the center of the measurement pipe P, as shown in Figure 5, and is an inclined surface that protrudes inward at the top. Furthermore, a plurality of uneven portions 2k consisting of vertical grooves are formed along the longitudinal direction on the contact surface 2l.

[0020] The lid part 3 is provided with pressing pieces 3b, which are arranged on its closing surface 3a and press the measuring tube P from above by uniformly distributing force so that the pressing surface is a polyhedron consisting of multiple small faces, and pressing the measuring tube P on the base part 2b, respectively; a hook-shaped locking part 3d, which is arranged on the outer surface 3c and locks to the lockable part 2j, which is arranged on the outer surface 3c, by closing the lid part 3; and an unlocking button 3f, which is arranged on the top surface 3e and unlocks the locking part 3d by pressing it.

[0021] An elastic body 3i made of a compression coil spring is built into the gap 3h in the lid 3 between the pressing piece 3b provided on the closing surface 3a and the elastic body fixing part 3g provided on the top surface 3e. As a result, a downward pressing force is always generated in the pressing piece 3b due to the repulsive force of the elastic body 3i, and when the measurement pipe P is placed on the base 2b and the lid 3 is closed and locked, the pressing piece 3b presses the measurement pipe P between itself and the base 2b with an appropriate pressing force from above.

[0022] In particular, in the conventional structure in which pressing force is applied from above mechanically and clamped without using pressing force from a spring or the like, variations in pressing strength occur due to variations in the dimensions of the parts, whereas in this embodiment, the pressing force from the elastic body 3i reduces fluctuations in pressing strength due to variations in the parts of the pressing piece 3b.

[0023] When attaching the clamp-on mechanism 1 to the measurement pipe P, the lid 3 is opened, the measurement pipe P is placed on the front and rear bases 2b, and the lid 3 is closed, as shown in Figure 2. When the lid 3 is closed, the locking portion 3d of the lid 3 is locked into the lockable portion 2j on the side of the main body 2, and the lid 3 is in the locked state as shown in Figures 1, 4, and 5. This locked state cannot be released unless the unlock button 3f linked to the locking portion 3d is pressed.

[0024] In this way, the straight-tube-shaped measurement pipe P is clamped and held by the holding part composed of the base part 2b of the main body part 2, the side wall part 2c, and the pressing piece 3b of the lid part 3. The measurement pipe P held by the holding part of the clamp-on mechanism 1 originally has a circular cross section. As shown in Figure 2, when the measurement pipe P is placed on the base part 2b, the movement of the measurement pipe P in the width direction is restricted by the side wall parts 2c on both sides of the base part 2b.

[0025] When the lid 3 is closed on the main body 2, the measurement tube P, which has a nearly circular cross section as shown in FIG. 5, is pressed from above and below by the pressing pieces 3b and the base 2b as shown in FIG. 6, and the measurement tube P is expanded between the side wall portions 2c in the width direction. However, its size is restricted from both sides by the side wall portions 2c, and the measurement tube P is deformed into a nearly elliptical cross section that is expanded in the width direction.

[0026] The surface of the base 2b, i.e., the surface of the protective film 2f, is shaped as an arcuate surface that follows a substantially elliptical shape that expands in the width direction. By forming it in this manner, the two bases 2b are in close contact with the lower part of the measurement pipe P, and the ultrasonic wave emitted from one of the piezoelectric vibrators 2d propagates through the measurement pipe P as a guide wave via the acoustic matching layer 2e and the protective film 2f, and then enters the other piezoelectric vibrator 2d.

[0027] In addition, the contact surface 2l of the side wall portion 2c is an inclined surface that is inclined so that the upper part covers over it, that is, so that the upper part protrudes inward, and the contact point of the contact surface 2l of the side wall portion 2c with the measuring tube P is slightly above the point of the measuring tube P that is widest in the width direction.

[0028] In this way, by providing a pair of side wall portions 2c that restrict the measurement tube P deformed by pressure from above and below from the width direction with the abutment surfaces 2l, it is possible to prevent the measurement tube P from becoming crushed vertically over time and becoming more flat.

[0029] In addition, due to the measurement principle of the ultrasonic flowmeter, even if the measurement pipe P is deformed, the cross-sectional area of ​​the measurement pipe P when deformed is required to be always constant, and it is not desirable for the cross-sectional area to change every time the lid part 3 is opened or closed. Therefore, it is preferable that the change in the cross-sectional area of ​​the measurement pipe P due to the appropriate pressing force of the pressing piece 3b on the measurement pipe P is always constant.

[0030] The fluid measuring unit 2h transmits various data such as the propagation time of the guided wave in the measuring pipe P based on the incidence and emission of ultrasonic waves by the pair of piezoelectric vibrators 2d to a processing device, which is an external device, via the cable 2i.

[0031] The processing device can measure the flow rate of the fluid flowing in the measuring pipe P by calculation based on the flow velocity calculated from the time difference in the propagation time of the obtained guided wave in the measuring pipe P and the cross-sectional area of ​​the measuring pipe P.

[0032] The measurement processing of the fluid flow velocity and flow rate may be performed by a processing unit that is installed inside the main body 2 and connected to the fluid measuring unit 2h. In such a case, the fluid flow velocity, flow rate information, etc. measured by the processing unit having a calculation function will be transmitted from the processing unit to an external device via the cable 2i.

[0033] In this way, the fluid measuring unit 2h measures the flow velocity and flow rate of the fluid flowing in the measuring pipe P based on the time difference in the transmission time of the ultrasonic waves that propagate as guide waves through the measuring pipe P as a medium. However, as long as the flow velocity and flow rate of the fluid flowing in the measuring pipe P can be measured using the input and output of ultrasonic waves from the pair of piezoelectric vibrators 2d, any appropriate flow velocity and flow rate measurement method can be adopted.

[0034] It is preferable that the calculation processing by the fluid measuring unit 2h is performed by an IC chip or the like built into the main body unit 2. Then, various data obtained, such as the flow rate, is transmitted to the outside via a cable 2i.

[0035] Furthermore, the side wall 2c has uneven portions 2k on the contact surface 2l in order to minimize the attenuation of ultrasonic waves, that is, a plurality of uneven portions 2k are provided in the longitudinal direction of the measurement pipe P. Providing these plurality of uneven portions 2k has the effect of reducing the contact area and preventing the attenuation of ultrasonic waves.

[0036] Furthermore, by positioning the contact point of the contact surface 2l of the side wall portion 2c with the measurement tube P slightly above the widest point of the measurement tube P, pressure is generated in the direction from the contact point toward the central axis of the measurement tube P, and a stronger adhesion force can be generated for the measurement tube P placed on the base portion 2b.

[0037] In this way, the clamp-on mechanism 1 of the ultrasonic flowmeter according to the present invention makes it possible to attach the fluid measuring unit 2h with an appropriate pressing force while preventing plastic deformation of the measuring pipe P. In addition, an elastic structure using a spring or the like is used to apply pressure from above, and this elastic structure absorbs variations in the dimensional accuracy of the product, making it possible to apply a stable pressing force, improving the measurement accuracy of the flowmeter and extending the life of the measuring pipe. [Explanation of symbols]

[0038] 1 Clamp-on mechanism 2 Main body 2b Base 2c Side wall part 2d piezoelectric vibrator 2e acoustic matching layer 2f protective film 2h Fluid Measurement Department 2k Concave and convex part 2l Face-to-face 3 cover 3b pressure film P assay tube

Claims

1. A clamp-on mechanism for an ultrasonic flow meter includes a holding section that sandwiches and holds a straight measuring pipe, and an ultrasonic transmitting / receiving section that has a pair of piezoelectric vibrators that are provided at two positions in the longitudinal direction of the measuring pipe and that transmit and receive ultrasonic waves, the holding portion comprises a pair of pedestal portions on which the measurement tube is placed, the pedestal portions being provided corresponding to the pair of piezoelectric vibrators; a pair of pressing pieces that press the measurement tube on the pair of pedestal portions from above by an elastic force of an elastic body; and two pairs of side wall portions that are provided between the pair of pedestal portions and the pair of pressing pieces and that restrict movement of the measurement tube that expands in the width direction from both sides of the measurement tube when the measurement tube is pressed from above and below, a clamp-on mechanism for an ultrasonic flowmeter, characterized in that the abutment surface of each of the two pairs of side wall portions that make up the side wall portions with respect to the measuring tube is an inclined surface that is inclined so that the upper part protrudes inward, and the abutment point of the abutment surface with respect to the measuring tube is slightly higher than the part of the measuring tube that widens most in the width direction.

2. A clamp-on mechanism for an ultrasonic flow meter includes a holding section that sandwiches and holds a straight measuring pipe, and an ultrasonic transmitting / receiving section that has a pair of piezoelectric vibrators that are provided at two positions in the longitudinal direction of the measuring pipe and that transmit and receive ultrasonic waves, the holding portion comprises a pair of pedestal portions on which the measurement tube is placed, the pedestal portions being provided corresponding to the pair of piezoelectric vibrators; a pair of pressing pieces that press the measurement tube on the pair of pedestal portions from above by an elastic force of an elastic body; and two pairs of side wall portions that are provided between the pair of pedestal portions and the pair of pressing pieces and that restrict movement of the measurement tube that expands in the width direction from both sides of the measurement tube when the measurement tube is pressed from above and below, A clamp-on mechanism for an ultrasonic flow meter, characterized in that each of the two pairs of side wall portions is provided with a plurality of concave and convex portions along the direction of the central axis of the measuring pipe.

3. 3. The clamp-on mechanism for an ultrasonic flowmeter according to claim 2, wherein the plurality of concave and convex portions are formed of grooves extending in the vertical direction.

4. The device is configured to include a main body that connects to an external device and a lid that is openably and closably connected to the main body.

4. The clamp-on mechanism of an ultrasonic flowmeter according to claim 1, wherein a pair of the base portions and two pairs of the side wall portions are arranged on the main body portion, and a pair of the pressing pieces are arranged on the lid portion.

5. A clamp-on mechanism for an ultrasonic flow meter described in any one of claims 1 to 3, characterized in that the pair of piezoelectric vibrators are arranged symmetrically facing each other diagonally upward via a pair of acoustic matching layers arranged at the bottom of the pair of base portions.

6. 6. The clamp-on mechanism of an ultrasonic flowmeter according to claim 5, wherein an ultrasonic wave emitted from one of the piezoelectric vibrators propagates through the measuring tube as a guide wave via the acoustic matching layer, and is then incident on the other of the piezoelectric vibrators.

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