Clamp-on mechanism for ultrasonic flowmeters

Abstract

To provide a clamp-on mechanism for an ultrasonic flow meter that fixes a measuring tube with a suitable and stable pressing force. [Solution] The pressing piece 6 is composed of a cylindrical portion 6a and a pipe abutment 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 accommodated in the cylindrical portion 6a of the pressing piece 6, and is compressed between the top surface portion 5f of the accommodation portion 5c and the pipe abutment surface portion 6b, generating a repulsive force. In this state, the pressing piece 6 is pushed into the accommodation portion 5c up to the top of the standing piece 5h against the repulsive force, and then the pressing piece 6 is rotated. The rotation direction of the pressing piece 6 differs depending on the left and right accommodation portions 5c, and by rotating one clockwise and the other counterclockwise, the locking piece 6d of the pressing piece 6 is locked to the top of the standing piece 5h.

Description

[Technical field]

[0001] The present invention relates to a clamp-on mechanism for an ultrasonic flowmeter that uses an existing synthetic resin fluid pipeline as a measurement pipe and later fixes a fluid measuring unit thereto. [Background technology]

[0002] Patent Document 1 discloses a clamp-on ultrasonic flowmeter in which a guided wave is generated by ultrasonic waves propagating in the pipe length direction using a measuring pipe through which a fluid flows as a medium, using an ultrasonic transmitting / receiving element made of a piezoelectric transducer.

[0003] In such a clamp-on ultrasonic flowmeter, when the fluid measuring unit is fixed around the existing measuring pipe, the ultrasonic transmission part needs to be tightly attached to the measuring 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 part and the measuring pipe.

[0004] When the fluid measuring unit is clamped to the measuring tube, in order to improve the transmission characteristics of ultrasonic waves to the measuring tube, the above-mentioned synthetic rubber or the like is interposed as a material to fill the gap between the ultrasonic transmission part and the measuring tube. In such a case, however, in order to transmit a guided wave of sufficient magnitude to the measuring tube, it is necessary to increase the pressing force of the synthetic rubber against the measuring tube. [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 force of the fluid measuring unit pressing against the measurement tube from the outside is increased and the force applied is greater than the force at which the synthetic resin measurement tube undergoes plastic deformation, the measurement tube will remain deformed and will have difficulty returning to its original shape, and the cross-sectional area of ​​the measurement tube will be prone to change, affecting measurement accuracy and possibly resulting in increased pressure loss and damage to the measurement tube or the like.

[0007] In addition, the pressing force applied to the measurement tube by the fluid measuring unit is generated by a reaction force caused by deformation of each part that constitutes the clamp-on mechanism of the flowmeter when it is clamped. However, this force varies depending on the machining precision of each part and the assembly operation, which causes the problem of affecting the measurement precision.

[0008] An object of the present invention is to provide a clamp-on mechanism for an ultrasonic flowmeter that solves the above-mentioned problems, applies a suitable and stable pressing force to the measurement tube, prevents plastic deformation of the measurement tube, and enables an ultrasonic signal to be obtained with high accuracy. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the clamp-on mechanism of an ultrasonic flowmeter according to the present invention is composed of a main body on which a straight-shaped measuring tube is placed, and a lid which is openably and closably connected to the main body via a connecting part, and in the clamp-on mechanism of an ultrasonic flowmeter which clamps and 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 / receiving parts which transmit and receive ultrasonic waves to and from the measuring tube, and the lid is provided with a pair of pressing pieces which press the measuring tube placed on the base from above by the elastic force of an elastic body. Effect of the Invention

[0010] The clamp-on mechanism of the ultrasonic flowmeter according to the present invention can hold the measurement tube with an appropriate pressing force while preventing plastic deformation of the measurement tube. In particular, an elastic body made of a spring or the like is used for pressing from above, and this elastic body can absorb variations in the dimensional accuracy of the product and apply a stable pressing force, improving the accuracy of flow measurement and extending the life of the measurement tube. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view of the clamp-on mechanism attached to the measurement tube. [Diagram 2] FIG. 2 is a perspective view of the measuring tube placed on the base with the lid open. [Diagram 3] 2 is a cross-sectional view taken along line AA' in FIG. [Figure 4] 2 is an enlarged cross-sectional view taken along line BB' in FIG. 1. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 4 is an enlarged perspective view of a pressing piece with the pipe contact surface facing upward. [Figure 8] FIG. 11 is an enlarged perspective view of a pressing piece of another embodiment with the pipe abutment surface facing upward. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0013] The clamp-on mechanism 1, which is approximately a rectangular parallelepiped, has a bottom surface on which the measurement tube P is placed and is composed of a main body 2 to which a connection cable can be connected, and an openable and closable lid 3 that is connected to the main body 2 via a connecting portion 2a.

[0014] Fig. 3 is a cross-sectional view taken along line A-A' in the longitudinal direction of Fig. 1, and Fig. 4 is an enlarged cross-sectional view taken along line B-B' in the width direction. Inside the main body 2, a pair of base parts 2b, each of which is provided at two positions in the longitudinal direction and has an arc-shaped tray-like cross section for placing the measurement tube P, and side wall parts 2c are provided on both sides in the width direction of the base parts 2b for restricting the movement of the measurement tube P in the width direction. The side wall parts 2c play a role in restricting the movement of the measurement tube P in the width direction, but are arranged at a position that does not obstruct the propagation of ultrasonic waves.

[0015] A pair of pedestal portions 2b are provided with piezoelectric transducers 2d, which are symmetrically arranged facing each other diagonally upward via an acoustic matching layer 2e fixed to the lower portion of the pedestal portion 2b. The acoustic matching layer 2e, which is made of a synthetic resin material or the like, improves the ultrasonic wave incidence and reflection characteristics with the piezoelectric transducers 2d.

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

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

[0018] Fig. 5 is an exploded perspective view of the inner lid part 5, and Fig. 6 is a perspective view of the inner lid part 5 in an assembled state. The inner lid part 5 has a bearing part 5b that engages with a shaft body (not shown) of the connecting part 2a, a pressing piece 6, and an accommodating part 5c that accommodates an elastic body 7 having a repulsive force, for example, a coil spring. Note that although a coil spring is shown as an example of the elastic body 7, various spring bodies, rubber bodies, etc. other than a coil spring can be appropriately used.

[0019] The storage section 5c is composed of a circular hole 5d through which the pressing piece 6 is inserted, a pair of storage walls 5e standing from the edge of the circular hole 5d, and a top surface 5f connecting the tops of the storage walls 5e. These top surfaces 5f are inserted into insertion holes 4e provided in the top surface 4c of the outer lid section 4 as shown in FIG. 1, and are flush with the top surface 4c.

[0020] Furthermore, a pair of notches 5g cut outwardly are arranged on the edge of the circular hole portion 5d between the pair of accommodating wall portions 5e, and a pair of upright pieces 5h shorter in height than the accommodating wall portions 5e are arranged on the edge of the circular hole portion 5d adjacent to these notches 5g.

[0021] The pair of cutout portions 5g and the pair of standing pieces 5h are disposed so as to face each other relative to the circular hole portion 5d, and a straight line connecting the pair of standing pieces 5h is parallel to the longitudinal direction of the lid portion 3.

[0022] In addition, the pair of notches 5g of one storage section 5c are adjacent to the pair of standing pieces 5h in a clockwise direction around the circular hole 5d, i.e., on the left side, and the pair of notches 5g of the other storage section 5c are adjacent to the pair of standing pieces 5h in a counterclockwise direction around the circular hole 5d, i.e., on the right side. Therefore, the straight line connecting the pair of notches 5g in the left and right storage sections 5c is inclined at a predetermined angle d1 on both the positive and negative sides with respect to the straight line in the longitudinal direction of the lid section 3.

[0023] In this way, the straight lines connecting the pair of cutouts 5g are arranged in a V-shape, making it possible to effectively utilize the space present in the lower center of the V-shape where there is no cutout 5g. However, as long as a sufficient space can be secured between the storage portions 5c, the straight lines connecting the pair of cutouts 5g on the left and right may be parallel to each other.

[0024] 7 is an enlarged perspective view of the pressing piece 6 with the pipe contact surface 6b facing upward. The pressing piece 6 is composed of a cylindrical portion 6a and the pipe contact surface 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.

[0025] The diameter of the outer surface of the cylindrical portion 6a is slightly smaller than the diameter of the inner surface of the circular hole portion 5d of the accommodating 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 cutout portions 5g of the accommodating portion 5c.

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

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

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

[0029] When assembling the inner lid part 5, as shown in Fig. 5, the pressing piece 6 and the elastic body 7 are pushed upward from below with the pipe contact surface 6b of the pressing piece 6 facing downward. Then, the pressing piece 6 is inserted into the cylindrical part 6a and the pair of locking pieces 6d so as to be locked into the circular hole part 5d and the pair of notches 5g of the storage part 5c.

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

[0031] The rotation direction of the pressing piece 6 differs depending on the left and right storage parts 5c, and by rotating one clockwise and the other counterclockwise, the locking piece 6d of the pressing piece 6 is locked to the top of the standing piece 5h. In this way, the installation work of the pressing piece 6 to the inner lid part 5 is completed as shown in Figure 6.

[0032] As shown in FIG. 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] In addition, when the pressing piece 6 is pushed into the housing portion 5c, the pressing piece 6 does not rotate in the opposite direction to the direction in which the standing piece 5h is located because there is a stopper piece (not shown). Furthermore, the pressing piece 6 can rotate in the rotation direction by a predetermined angle d1, and the pressing piece 6 cannot rotate any further due to the stopper (not shown).

[0034] When attaching the clamp-on mechanism 1 to the measurement pipe P, the lid 3 is opened as shown in Fig. 2, the measurement pipe P is placed on the front and rear bases 2b, and the lid 3 is closed. When closing the lid 3, the locking part 4b of the lid 3 is locked to the lockable part 2j on the side of the main body 2, and the lid 3 is in a locked state as shown in Figs. 1, 3, and 4. This locked state will not be released unless the unlock button 4d linked to the locking part 4b is pressed to open the lid 3.

[0035] The pressing piece 6, which constantly generates a downward pressing force due to the repulsive force of the elastic body 7, presses the measurement tube P between the base part 2b and the measurement tube P with an appropriate pressing force from above when the measurement tube P is placed on the base part 2b and the lid part 3 is closed and locked.

[0036] In particular, in the conventional structure in which the components are clamped by simply pressing mechanically from above without using the pressing force of a spring or the like, variations in pressing strength occur due to variations in the dimensions of the components, whereas in this embodiment, the pressing force from the elastic body 7 reduces the fluctuations in pressing strength caused by variations in the components of the pressing piece 6.

[0037] When the cover 3 is closed on the main body 2, the measurement tube P is held in the vertical direction by the base 2b and the pressing piece 6, and in the width direction by the side wall 2c.

[0038] When the measurement tube P is held in this manner, the two pedestal parts 2b come into close contact with the lower part of the measurement 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 measurement tube P as guided waves via the acoustic matching layer 2e and the pedestal part 2b, and then enter the other piezoelectric transducer 2d. Various data such as the transmission time of the guided wave in the measurement tube P based on the incidence and emission of ultrasonic waves by the pair of piezoelectric transducers 2d are transmitted to a processing device, which is an external device, via the cable 2f.

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

[0040] The measurement process of the flow velocity and the flow rate of the fluid may be performed by a processing unit that is provided inside the main body 2 and connected to the piezoelectric vibrator 2d. In this case, the flow velocity, flow rate information, etc. of the fluid obtained by the processing unit having a calculation function are transmitted to an external device via the cable 2f.

[0041] In this way, the clamp-on mechanism 1 or the above-mentioned processing device measures the flow velocity and flow rate of the fluid flowing in the measurement tube P based on the time difference in the transmission time of ultrasonic waves propagating as guide waves using the measurement tube P as a medium, but it is also possible to measure the flow velocity and flow rate of the fluid by propagating an ultrasonic beam from a pair of piezoelectric transducers 2d into the fluid in the measurement tube P.

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

[0043] In this way, by making the groove widths and inclination angles of the first and second groove portions 6e', 6f' and the first and second inclined surfaces 6g', 6h' of the pressing piece 6' different, the clamp-on mechanism 1 is able to hold two types of measuring tubes P with different diameters.

[0044] That is, when a measurement pipe P with a small diameter is held, the pressing piece 6' is attached to the accommodating part 5c so that the first groove portion 6e' is parallel to the measurement pipe P, and when a measurement pipe P with a large diameter is held, the pressing piece 6' is attached to the accommodating part 5c so that the second groove portion 6f' is parallel to the measurement pipe P. By arranging the pair of pressing pieces 6' in reverse on the left and right, it is possible to appropriately select the first groove portion 6e' and the second groove portion 6f' which are linear.

[0045] The curved surface of the base portion 2b on which the measurement tube P is placed is adapted to fit the outer surface of the measurement tube P to be placed, but when attaching the pressing piece 6', the curved surface of the base portion 2b is adapted to fit the outer surface of a measurement tube P with a larger diameter.

[0046] Moreover, the elastic body 7 that presses the pressing piece 6' can also be selected depending on the measurement pipe P. In consideration of plastic deformation due to the pressing force of the pressing piece 6' against the measurement pipe P, when the pressing piece 6' is attached so that the first groove portion 6e' is parallel to the measurement pipe P, an elastic body 7 with strong elasticity and holding power is arranged. On the other hand, when the pressing piece 6' is attached so that the second groove portion 6f' is parallel to the measurement pipe P, it is preferable to arrange an elastic body 7 with weak elasticity.

[0047] In this way, the clamp-on mechanism 1 of the ultrasonic flowmeter according to the present invention makes it possible to hold the measurement tube P with an appropriate pressing force while preventing plastic deformation of the measurement 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 can absorb variations in the dimensional accuracy of the product and apply a stable pressing force, improving the measurement accuracy of the flowmeter and extending the life of the measurement tube P. [Explanation of symbols]

[0048] 1 Clamp-on mechanism 2 Main unit 2b Pedestal 2d Piezoelectric transducer 3 Lid 4 Outer lid part 5 Inner lid 5c Storage section 5d Circular hole 5e Containment wall 5f Top part 5g Notch 5h standing piece 6, 6' Pressing piece 6a Cylindrical part 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. A clamp-on mechanism for an ultrasonic flowmeter is provided which is composed of a main body on which a straight measuring tube is placed and a lid which is openably and closably connected to the main body via a connecting part, and which clamps and holds the measuring tube by closing the lid, the main body portion includes a base portion on which the measurement pipe is placed, and a pair of ultrasonic transmission / reception portions that transmit and receive ultrasonic waves with respect to the measurement pipe, A clamp-on mechanism for an ultrasonic flow meter, characterized in that the lid portion is provided with a pair of pressing pieces that press the measuring tube placed on the base portion from above by the elastic force of an elastic body.

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

3. The cover portion has a pair of accommodating portions for accommodating the pressing pieces, the accommodation portion is composed of a circular hole portion through which the pressing piece is inserted, a pair of accommodation walls standing on edges of the circular hole portion, and a top surface portion connecting top portions of the accommodation walls, 3. The clamp-on mechanism for an ultrasonic flowmeter according to claim 2, wherein the pressing piece is accommodated together with the elastic body in the accommodation portion.

4. a pair of notches that are cut outwardly and face the circular hole between the pair of storage walls, and a pair of standing pieces that are lower in height than the storage walls and face the circular hole are disposed on the edge of the circular hole adjacent to the pair of notches, The pressing piece is composed of a cylindrical portion and a pipe abutment surface portion that closes the top of the cylindrical portion, and a pair of locking pieces that protrude outward are provided on the bottom edge of the cylindrical portion, 4. The clamp-on mechanism of an ultrasonic flowmeter 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 into the circular hole portion and the cutout portion of the accommodating portion, and then rotating the pressing piece to lock the locking piece onto the top of the standing piece.

5. 5. The clamp-on mechanism of an ultrasonic flowmeter according to claim 4, wherein a center line that bisects the acute angle between the intersecting first and second groove portions is parallel to center lines of the pair of opposing locking pieces.

6. the pair of notches of one of the accommodating portions are adjacent to the pair of standing pieces of one of the accommodating portions in a clockwise direction around the circular hole portion, 5. The clamp-on mechanism of an ultrasonic flowmeter according to claim 4, wherein the pair of notches of the other accommodating portion are adjacent to the other pair of standing pieces in a counterclockwise direction around the circular hole portion.

7. The clamp-on mechanism of an ultrasonic flowmeter according to any one of claims 2 to 6, characterized in that the groove widths of the first and second groove portions and the inclination angles of the slopes arranged on both sides of the first and second groove portions are different from each other.

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