Clamp-on mechanism for ultrasonic flowmeter

Abstract

This invention provides a clamp-on mechanism for an ultrasonic flow meter that secures the measuring tube with appropriate and stable pressure. [Solution] The pressing piece 6 is composed of a cylindrical portion 6a and a pipe contact surface portion 6b that closes the top of the cylindrical portion 6a, and a pair of locking pieces 6d that protrude outward are provided on the bottom edge 6c of the cylindrical portion 6a. The elastic body 7 is housed within the cylindrical portion 6a of the pressing piece 6 and is compressed between the top surface portion 5f of the housing portion 5c and the pipe contact surface portion 6b, generating a repulsive force. In this state, the pressing piece 6 is pushed into the housing portion 5c against the repulsive force up to above the upright piece 5h, and then the pressing piece 6 is rotated. The direction of rotation of the pressing piece 6 differs for the left and right housing portions 5c, with one rotating clockwise and the other counterclockwise, thereby locking the locking pieces 6d of the pressing piece 6 onto the top of the upright piece 5h.

Description

Technical Field

[0001] The present invention relates to a clamp-on mechanism of an ultrasonic flowmeter that uses an existing synthetic resin fluid pipeline as a measurement pipe and fixedly attaches a fluid measurement unit retrospectively.

Background Art

[0002] Patent Document 1 discloses a clamp-on type ultrasonic flowmeter that generates a guided wave by ultrasonic waves propagating in the pipe length direction using a measurement pipe through which a fluid flows as a medium by an ultrasonic transmission / reception element composed of a piezoelectric vibrator.

[0003] In such an ultrasonic flowmeter with a clamp-on structure, when fixing a fluid measurement unit around an existing measurement pipe, it is necessary to closely attach an ultrasonic transmission component to the measurement pipe in order to efficiently transmit ultrasonic waves. Therefore, the adhesion is improved by sandwiching a soft material such as synthetic rubber or grease between the ultrasonic transmission component and the measurement pipe.

[0004] When the fluid measurement unit is clamped to the measurement pipe, in order to improve the transmission characteristics of ultrasonic waves to the measurement pipe, the above-mentioned synthetic rubber or the like is interposed as a material for filling the gap between the ultrasonic transmission component and the measurement pipe. In such a case, however, in order to transmit a guided wave of sufficient size to the measurement pipe, it is necessary to increase the pressing strength of the synthetic rubber against the measurement pipe.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, if the external pressure applied to the measuring tube by the fluid measuring unit is increased to a force exceeding the plastic deformation of the synthetic resin measuring tube, the measuring tube will remain deformed. This makes it difficult for the tube to return to its original shape, causing the cross-sectional area of ​​the measuring tube to change easily, affecting measurement accuracy, and potentially leading to increased pressure loss, breakage, or damage to the measuring tube.

[0007] Furthermore, the pressing force applied to the measuring tube by the fluid measuring unit is generated by the reaction force due to the deformation of each component constituting the flow meter's clamp-on mechanism during clamping. However, this force can change depending on the manufacturing precision of each component and the assembly process, which can affect the measurement accuracy.

[0008] The object of the present invention is to solve the above-mentioned problems and provide a clamp-on mechanism for an ultrasonic flow meter that applies an appropriate and stable pressing force to the measuring tube, thereby preventing plastic deformation of the measuring tube and enabling accurate acquisition of ultrasonic signals. [Means for solving the problem]

[0009] The clamp-on mechanism for an ultrasonic flow meter according to the present invention, which achieves the above objective, comprises a main body on which a straight tubular measuring tube is placed, and a lid that is connected to the main body via a connecting part so as to be openable and closable, wherein the clamp-on mechanism for an ultrasonic flow meter holds the measuring tube by clamping it when the lid is closed, wherein the main body comprises a base on which the measuring tube is placed, and a pair of ultrasonic transmitting and receiving units that transmit and receive ultrasonic waves to and from the measuring tube, and the lid is provided with a pair of pressing pieces that press the measuring tube placed on the base from above with an elastic force from an elastic body. [Effects of the Invention]

[0010] The clamp-on mechanism of the ultrasonic flow meter according to the present invention can hold the measuring tube with appropriate clamping force while preventing plastic deformation of the measuring tube. In particular, an elastic body made of a spring or the like is used for the upward pressure, and this elastic body absorbs variations in the dimensional accuracy of the product, allowing a stable clamping force to be applied, improving the accuracy of flow measurement and extending the life of the measuring tube. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of the clamp-on mechanism attached to the measuring tube. [Figure 2] This is a perspective view showing the measuring tube placed on the base with the lid open. [Figure 3] This is a cross-sectional view along the line A-A' in Figure 1. [Figure 4] This is an enlarged cross-sectional view along the line B-B' in Figure 1. [Figure 5] This is an exploded perspective view of the inner lid. [Figure 6] This is a perspective view of the assembled inner lid. [Figure 7] This is an enlarged perspective view of the pressing piece with the pipe contact surface facing upwards. [Figure 8] This is an enlarged perspective view of a pressing piece in another embodiment, with the pipe contact surface facing upwards. [Modes for carrying out the invention]

[0012] The present invention will be described in detail based on the illustrated embodiments. Figure 1 is a perspective view of the clamp-on mechanism attached to a synthetic resin measuring tube, and Figure 2 is a perspective view of the mechanism with the lid open from the state shown in Figure 1.

[0013] The clamp-on mechanism 1, which is roughly rectangular in shape, consists of a main body 2 having a bottom surface on which the measuring tube P is placed and to which a connecting cable can be connected, and an openable and closable lid 3 that is connected to the main body 2 via a connecting part 2a.

[0014] FIG. 3 is a cross-sectional view taken along the longitudinal line A-A' of FIG. 1, and FIG. 4 is an enlarged cross-sectional view taken along the widthwise line B-B'. Inside the main body 2, there are provided a pair of pedestal portions 2b that are provided at two locations in the longitudinal direction and have an arcuate cross-section for placing the measuring tube P thereon in a dish-like shape, and side wall portions 2c for restricting the movement of the measuring tube P in the width direction are provided on both sides in the width direction of these pedestal portions 2b. Further, the side wall portions 2c serve to restrict the movement of the measuring tube P in the width direction, and are arranged at positions that do not impede the propagation of ultrasonic waves.

[0015] Piezoelectric vibrators 2d are respectively arranged on the pair of pedestal portions 2b, and these piezoelectric vibrators 2d are symmetrically arranged obliquely upward facing each other through an acoustic matching layer 2e fixed to the lower part of the pedestal portion 2b. The acoustic matching layer 2e made of a synthetic resin material or the like improves the ultrasonic incident and reflection characteristics with the piezoelectric vibrator 2d.

[0016] The lid portion 3 is composed of an outer lid portion 4 arranged to cover the outside of the lid portion 3, and an inner lid portion 5 surrounded by this outer lid portion 4 and having a pair of movable pressing pieces 6 made of a synthetic resin material attached along the longitudinal direction of the bottom surface 5a. Further, on the outer surface 4a on the opposite side of the connecting portion 2a of the outer lid portion 4, a pair of hook-shaped locking portions 4b are provided.

[0017] When the lid portion 3 is closed with respect to the main body portion 2, the locking portion 4b is locked to the locked portion 2j of the main body portion 2. On the top surface 4c of the outer lid portion 4, there is provided an unlocking button 4d for unlocking by pressing the locking portion 4b.

[0018] FIG. 5 is an exploded perspective view of the inner lid portion 5, and FIG. 6 is a perspective view of the assembled state of the inner lid portion 5. The inner lid portion 5 has a bearing portion 5b that engages with a shaft body (not shown) of the connecting portion 2a, and a housing portion 5c that houses the pressing piece 6 and an elastic body 7 made of, for example, a coil spring having a repulsive force. Note that the elastic body 7 is exemplified by a coil spring, but various spring bodies, rubber bodies, etc. other than the coil spring can be appropriately adopted.

[0019] The accommodating portion 5c is composed of a circular hole portion 5d through which the pressing piece 6 is inserted, a pair of accommodating wall portions 5e erected from the edge of the circular hole portion 5d, and a top surface portion 5f connecting the tops of these accommodating wall portions 5e. As shown in FIG. 1, these top surface portions 5f are inserted into the insertion holes 4e provided on the top surface 4c of the outer lid portion 4 and are flush with the top surface 4c.

[0020] Furthermore, at the edge of the circular hole portion 5d between the pair of accommodating wall portions 5e, there are provided a pair of notch portions 5g that notch outward, and at the edge of the circular hole portion 5d adjacent to these notch portions 5g, there are arranged a pair of erected pieces 5h having a height lower than that of the accommodating wall portions 5e.

[0021] The pair of notch portions 5g and the pair of erected pieces 5h are both arranged so as to face the circular hole portion 5d, and the straight line connecting the pair of erected pieces 5h is parallel to the longitudinal direction of the lid portion 3.

[0022] Also, the pair of notch portions 5g of one accommodating portion 5c are adjacent to the pair of erected pieces 5h in the clockwise direction around the circular hole portion 5d, that is, on the left side, and the pair of notch portions 5g of the other accommodating portion 5c are adjacent to the pair of erected pieces 5h in the counterclockwise direction around the circular hole portion 5d, that is, on the right side. Therefore, the straight line connecting the pair of notch portions 5g in the left and right accommodating portions 5c is inclined at a predetermined angle d1 on the plus side and the minus side with respect to the straight line in the longitudinal direction of the lid portion 3.

[0023] In this way, by arranging the straight line connecting the pair of notch portions 5g in a "C" shape, it is possible to effectively utilize the space existing at the lower center of the "C" shape without the notch portions 5g. However, if sufficient space can be ensured between the accommodating portions 5c, the straight line connecting the pair of notch portions 5g may be parallel on the left and right.

[0024] FIG. 7 is an enlarged perspective view of the pressing piece 6 with the pipe contact surface portion 6b facing upward. The pressing piece 6 is composed of a cylindrical portion 6a and a pipe contact surface portion 6b closing the top of the cylindrical portion 6a, and a pair of locking pieces 6d protruding outward are provided at the bottom edge 6c of the cylindrical portion 6a.

[0025] The outer diameter of the cylindrical portion 6a is slightly smaller than the inner diameter of the circular hole portion 5d of the housing portion 5c, and the length connecting the tips of the pair of locking pieces 6d is slightly shorter than the length connecting the tips of the notches 5g of the housing portion 5c.

[0026] The pipe contact surface 6b that contacts the measuring pipe P is a polyhedron. The pipe contact surface 6b is provided with a linear first groove 6e and a second groove 6f that intersects with the first groove 6e, and both the first and second grooves 6e and 6f are horizontal and linear.

[0027] On the pipe contact surface 6b, four first inclined surfaces 6g are arranged on both sides of the first groove 6e, flanking the second groove 6f, and similarly, four second inclined surfaces 6h are arranged on both sides of the second groove 6f, flanking the first groove 6e.

[0028] The center line c that bisects the acute angle d2 between the intersecting first and second grooves 6e and 6f is parallel to the center line connecting the opposing pair of locking pieces 6d. Furthermore, the angle obtained by bisecting this acute angle d2 coincides with the predetermined angle d1 described above.

[0029] When assembling the inner lid 5, as shown in Figure 5, the pipe contact surface 6b of the pressing piece 6 is pointed downwards, and the pressing piece 6 and elastic body 7 are pushed upwards from below. Then, the pressing piece 6 is inserted into the cylindrical part 6a and the pair of locking pieces 6d so as to engage with the circular hole 5d and the pair of notches 5g of the housing part 5c.

[0030] In this process, the elastic body 7 is housed within the cylindrical portion 6a of the pressing piece 6, and is compressed between the top surface 5f and the pipe contact surface 6b of the housing portion 5c, generating a repulsive force. In this state, the pressing piece 6 is pushed into the housing portion 5c against the repulsive force up to above the upright piece 5h, and then the pressing piece 6 rotates.

[0031] The rotation direction of the pressing piece 6 differs depending on whether it is in the left or right housing section 5c. By rotating one clockwise and the other counterclockwise, the locking piece 6d of the pressing piece 6 is locked onto the top of the upright piece 5h. In this way, as shown in Figure 6, the installation of the pressing piece 6 to the inner lid section 5 is completed.

[0032] As shown in Figure 4, the compressed elastic body 7 is fixed without displacement by a fixing piece 6i provided on the bottom surface of the cylindrical portion 6a and a fixing piece 5i provided on the back surface of the top surface portion 5f.

[0033] Furthermore, when the pressing piece 6 is pushed into the housing section 5c, a stopper piece (not shown) exists on the opposite side of the direction in which the upright piece 5h is located, so the pressing piece 6 cannot rotate in the opposite direction. Moreover, the pressing piece 6 can rotate by a predetermined angle d1 in the rotational direction, and it cannot rotate beyond that point due to the stopper (not shown).

[0034] When attaching the clamp-on mechanism 1 to the measuring tube P, open the lid 3 as shown in Figure 2, place the measuring tube P on the front and rear bases 2b, and then close the lid 3. When closing the lid 3, the locking part 4b of the lid 3 is locked to the locking part 2j on the side of the main body 2, and the lid 3 enters the locked state as shown in Figures 1, 3, and 4. This locked state cannot be released unless the unlocking button 4d, which is linked to the locking part 4b, is pressed and the lid 3 is opened.

[0035] As a result of the repulsive force of the elastic body 7, the pressing piece 6 constantly generates a downward pressing force. When the measuring tube P is placed on the base portion 2b and the lid portion 3 is closed and locked, the pressing piece 6 presses the measuring tube P against the base portion 2b with an appropriate pressing force from above.

[0036] In particular, in conventional structures that simply mechanically press and clamp from above without using pressing force from springs or the like, variations in pressing strength occurred due to variations in the dimensions of the parts. In contrast, in this embodiment, the pressing force by the elastic body 7 reduces the variation in pressing strength due to variations in the parts of the pressing piece 6.

[0037] When the lid 3 is closed over the main body 2, the measuring tube P is held vertically by the base 2b and the pressing piece 6, and horizontally by the side wall 2c.

[0038] When the measuring tube P is held in this manner, the two base portions 2b are in close contact with the bottom of the measuring tube P, and ultrasonic waves are alternately emitted from the two piezoelectric transducers 2d. The ultrasonic waves emitted from one piezoelectric transducer 2d propagate through the measuring tube P as guided waves via the acoustic matching layer 2e and the base portions 2b, and then enter the other piezoelectric transducer 2d. Various data, such as the propagation time of the guided waves in the measuring tube P based on the input and output of ultrasonic waves by the pair of piezoelectric transducers 2d, are transmitted via cable 2f to an external device, which is a processing unit.

[0039] The processing device can measure the flow rate of the fluid flowing through the measuring tube P by performing calculations based on the flow velocity calculated from the time difference in the propagation time of the obtained guided wave in the measuring tube P and the cross-sectional area of ​​the measuring tube P.

[0040] The fluid velocity and flow rate may be measured by a processing unit located within the main unit 2 and connected to the piezoelectric vibrator 2d. In this case, the fluid velocity and flow rate information obtained by the processing unit, which is equipped with calculation processing functions, will be transmitted to an external device via cable 2f.

[0041] In this way, the clamp-on mechanism 1 or the processing device described above measures the fluid velocity and flow rate of the fluid flowing through the measuring tube P based on the time difference in the propagation time of ultrasonic waves propagated as guide waves through the measuring tube P. However, it is also possible to measure the fluid velocity and flow rate by propagating ultrasonic beams from a pair of piezoelectric transducers 2d into the fluid in the measuring tube P.

[0042] Figure 8 is a perspective view of a pressing piece 6' having a pipe contact surface 6b in another embodiment. The difference from the pressing piece 6 shown in Figure 7 is that the first and second grooves 6e and 6f of the pressing piece 6 in Figure 7 have the same groove width, whereas the first and second grooves 6e' and 6f' of the pipe contact surface 6b in Figure 8 have different groove widths. Also, the inclination angles of the first and second inclined surfaces 6g and 6h of the pressing piece 6 are the same, whereas the inclination angles of the first and second inclined surfaces 6g' and 6h' of the pressing piece 6' are different.

[0043] In this way, by making the groove width and inclination angle of the first and second grooves 6e'6f' and the first and second inclined surfaces 6g'6h' of the pressing piece 6' different, the clamp-on mechanism 1 becomes capable of holding two types of measuring tubes P with different diameters.

[0044] In other words, when holding a measuring tube P with a small diameter, the pressing piece 6' is attached to the housing 5c ​​so that the first groove 6e' is parallel to the measuring tube P, and when holding a measuring tube P with a large diameter, the pressing piece 6' is attached to the housing 5c ​​so that the second groove 6f' is parallel to the measuring tube P. By arranging the pair of pressing pieces 6' in opposite directions, it is possible to appropriately select the straight first groove 6e' and the second groove 6f'.

[0045] The curved surface of the base portion 2b on which the measuring tube P is placed is designed to match the outer surface of the measuring tube P being placed. However, when attaching the pressing piece 6', the curved surface of the base portion 2b is designed to match the outer surface of a larger diameter measuring tube P.

[0046] Furthermore, the elastic body 7 that presses the pressing piece 6' can be selected according to the measuring tube P. Considering the plastic deformation of the pressing piece 6' due to the pressing force on the measuring tube P, when the pressing piece 6' is installed so that the first groove 6e' is parallel to the measuring tube P, an elastic body 7 with strong elastic force and holding power is used. On the other hand, when the pressing piece 6' is installed so that the second groove 6f' is parallel to the measuring tube P, it is preferable to use an elastic body 7 with weak elastic force.

[0047] Thus, the clamp-on mechanism 1 of the ultrasonic flow meter according to the present invention makes it possible to hold the measuring tube P with an appropriate pressing force while preventing plastic deformation of the measuring tube P. In particular, an elastic body 7 made of a spring or the like is used for pressing from above, and this elastic body 7 absorbs variations in the dimensional accuracy of the product, allowing a stable pressing force to be applied, improving the measurement accuracy of the flow meter and extending the life of the measuring tube P. [Explanation of Symbols]

[0048] 1. Clamp-on mechanism 2 Main body 2b Base 2D piezoelectric vibrator 3 Lid 4 Outer lid part 5. Inner lid 5c Storage area 5d Circular hole 5e Containment wall section 5f Top part 5g Notch 5h standing piece 6, 6' Pressing piece 6a Cylindrical section 6b Pipe contact surface 6c bottom edge 6d locking piece 6e, 6e' First groove 6f, 6f' Second groove 6g, 6g' First slope 6h, 6h' Second slope 7 Elastic body c center line d1 Predetermined angle d2 acute angle P measurement tube

Claims

1. In a clamp-on mechanism for an ultrasonic flow meter, which consists of a main body on which a straight measuring tube is placed and a lid that is connected to the main body via a connecting part so as to be openable and closable, the clamp-on mechanism holds the measuring tube by closing the lid, The main body comprises a base on which the measuring tube is placed, and a pair of ultrasonic transmitting and receiving units that transmit and receive ultrasonic waves to and from the measuring tube. The clamp-on mechanism for an ultrasonic flow meter is characterized in that the lid portion is provided with a pair of pressing pieces that press the measuring tube, which is placed on the base portion, from above with the elastic force of an elastic body.

2. The clamp-on mechanism for an ultrasonic flow meter according to claim 1, characterized in that the pipe contact surface of the pressing piece is provided with a first horizontal and straight groove and a second horizontal and straight groove that intersects the first groove.

3. The lid portion has a pair of housing portions for housing the pressing piece, The housing portion consists of a circular hole through which the pressing piece is inserted, a pair of housing walls erected from the edge of the circular hole, and a top surface connecting the tops of the housing walls. The clamp-on mechanism for an ultrasonic flow meter according to claim 2, characterized in that the pressing piece is housed together with the elastic body in the housing.

4. The edge of the circular hole between the pair of housing walls is provided with a pair of notches that are cut outwards and face the circular hole, and the edge of the circular hole adjacent to the pair of notches is provided with a pair of upright pieces that are lower in height than the housing wall and face the circular hole. The pressing piece is composed of a cylindrical portion and a pipe contact surface portion that closes the top of the cylindrical portion, and the bottom edge of the cylindrical portion is provided with a pair of locking pieces that protrude outward. The clamp-on mechanism for an ultrasonic flow meter according to claim 3, characterized in that the pressing piece can be attached to the lid by inserting the cylindrical portion and the locking piece of the pressing piece through the circular hole and the notch of the housing portion, and then rotating the pressing piece to lock the locking piece onto the top of the upright piece.

5. The clamp-on mechanism for an ultrasonic flow meter according to claim 4, characterized in that the center line that bisects the acute angle between the intersecting first and second grooves is parallel to the center lines of the opposing pair of locking pieces.

6. The pair of notches in one of the housing portions are adjacent to the pair of upright pieces in a clockwise direction around the circular hole, The clamp-on mechanism for an ultrasonic flow meter according to claim 4, characterized in that the pair of notches in the other housing portion are adjacent to the other pair of upright pieces in a counterclockwise direction around the circular hole portion.

7. A clamp-on mechanism for an ultrasonic flow meter according to any one of claims 2 to 6, characterized in that the groove widths of the first and second grooves and the inclination angles of the slopes arranged on both sides of the first and second grooves are different.

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