Clamp-on mechanism for ultrasonic flowmeters

Abstract

To provide a clamp-on mechanism for an ultrasonic flow meter that fixes a measuring pipe with a moderate and stable pressing force. [Solution] The pressing piece 6 is composed of a cylindrical portion 6a and a pipe-contacting 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. An elastic body 7 is housed within 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-contacting 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 the top of the standing piece 5h, and then the pressing piece 6 is rotated. The rotation direction of the pressing piece 6 differs depending on whether it is a left or right housing portion 5c; by rotating one clockwise and the other counterclockwise, the locking pieces 6d of the pressing piece 6 are locked onto the top of the standing piece 5h.

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a clamp-on ultrasonic flowmeter in which a measuring pipe through which a fluid flows is used as a medium, and an ultrasonic transmitting / receiving element consisting of a piezoelectric vibrator generates guided waves by ultrasonic waves that propagate in the pipe length direction.

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

[0004] When the fluid measuring unit is clamped to the measuring pipe, 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 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 force of the fluid measuring unit pressing against the measuring tube from the outside is increased and the force applied is greater than the force that causes plastic deformation of the synthetic resin measuring tube, the measuring tube will remain deformed and will have difficulty returning to its original shape, which will make the cross-sectional area of ​​the measuring tube more likely to change and affect measurement accuracy, and may even result in increased pressure loss, or the measuring tube may be damaged or scratched.

[0007] Furthermore, the pressing force exerted by the fluid measuring unit on the measuring tube is generated by the reaction force caused by the deformation of each component that makes up the clamping mechanism of the flowmeter when it is clamped. However, this force varies depending on the machining precision of each component and the assembly operation, which can affect the measurement precision.

[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, and enables ultrasonic signals to be obtained with high accuracy. [Means for solving the problem]

[0009] In order to achieve the above object, the clamp-on mechanism according to the present invention is a clamp-on mechanism for an ultrasonic flowmeter, which comprises a main body on which a straight measuring tube is placed and a lid connected to the main body via a connecting part so as to be openable and closable, and which clamps and holds the measuring tube by closing the lid. a pair A base portion and disposed below the pair of base portions, a pair of ultrasonic transmitting and receiving units for transmitting and receiving ultrasonic waves to and from the measuring tube, and a pair of pressing pieces for pressing the measuring tube placed on the base from above on the cover. attachment The pipe contact surface of the pressing piece is provided with a first groove portion having a horizontal and linear first groove bottom and a substantially V-shaped cross section in the groove width direction. [Effects of the Invention]

[0010] The clamp-on mechanism of the ultrasonic flowmeter according to the present invention can hold the measuring tube with an appropriate pressing force while preventing plastic deformation 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 state in which the measuring tube is placed on the base and the lid is open. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA' in FIG. [Figure 4] FIG. 2 is an enlarged cross-sectional view taken along line BB' in FIG. [Figure 5] FIG. [Figure 6] FIG. 2 is a perspective view of the inner lid portion in an assembled state. [Figure 7] FIG. 10 is an enlarged perspective view of the pressing piece with the pipe contact surface facing upward. [Figure 8] FIG. 10 is an enlarged perspective view of a pressing piece of another embodiment with the pipe contact surface facing upward. [Figure 9] FIG. 10 is a perspective view of a pair of pressing pieces in another embodiment with the pipe contact surfaces facing upward. 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, and FIG. 2 is a perspective view of the clamp-on mechanism in the state shown in FIG. 1 with the lid portion opened.

[0013] The clamp-on mechanism 1, which is an approximately 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 connected to the main body 2 via a connecting part 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 portions 2b, each with an arc-shaped saucer-like cross section and on which the measurement tube P is placed, are provided at two positions in the longitudinal direction, and on both sides in the width direction of these base portions 2b, are sidewall portions 2c, which restrict movement of the measurement tube P in the width direction. Furthermore, the sidewall portions 2c play a role in restricting movement of the measurement tube P in the width direction, but are positioned so as not to obstruct the propagation of ultrasonic waves.

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

[0016] The lid 3 is composed of an outer lid 4 that is arranged to cover the outside of the lid 3, and an inner lid 5 that is surrounded by the outer lid 4 and has 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 portions 4b are provided on the outer surface 4a opposite the connecting portion 2a of the outer lid 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 (not shown) of the connecting part 2a, a pressing piece 6, and an accommodating part 5c that accommodates an elastic body 7 having a resilient force, such as a coil spring. Note that although a coil spring is shown as an example of the elastic body 7, various types of spring bodies, rubber bodies, etc. other than a coil spring can be used as appropriate.

[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 upright from the edge of the circular hole 5d, and a top surface 5f connecting the tops of these storage walls 5e. As shown in Figure 1, these top surfaces 5f are inserted into insertion holes 4e provided in the top surface 4c of the outer lid section 4 and are flush with the top surface 4c.

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

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

[0022] Furthermore, the pair of notches 5g of one of the storage sections 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 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 a line in the longitudinal direction of the lid section 3.

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

[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 storage 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 portion 5g of the storage 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 first groove portion 6e and a second groove portion 6f that intersects with the first groove portion 6e.

[0027] The first groove portion 6e on the pipe contact surface portion 6b is composed of a horizontal and linear first groove bottom portion 6g and four first inclined surfaces 6h arranged on both sides of this first groove bottom portion 6g, sandwiching the second groove portion 6f.

[0028] Similarly, the second groove portion 6f is composed of a horizontal and linear second groove bottom portion 6i and four second inclined surfaces 6j arranged on both sides of the second groove bottom portion 6i, sandwiching the first groove portion 6e.

[0029] The first and second groove bottoms 6g, 6i may have a linear shape other than a planar shape, as long as the cross section in the groove width direction is substantially V-shaped.

[0030] The center line c, which bisects the acute angle d2 between the intersecting first and second groove bottoms 6g and 6i, is parallel to the center line connecting the pair of opposing locking pieces 6d. The angle obtained by bisecting this acute angle d2 is the same as the predetermined angle d1 described above.

[0031] When assembling the inner lid portion 5, as shown in Fig. 5, the pipe contact surface 6b of the pressing piece 6 is faced downward, and the pressing piece 6 and the elastic body 7 are pushed upward from below. Then, the pressing piece 6 is inserted into the cylindrical portion 6a and the pair of locking pieces 6d so as to be locked into the circular hole portion 5d and the pair of notches 5g of the storage portion 5c.

[0032] 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 accommodation portion 5c and the pipe contact surface 6b, generating a repulsive force. In this state, the pressing piece 6 is pushed into the accommodation portion 5c up to above the standing piece 5h against the repulsive force, and then the pressing piece 6 rotates.

[0033] The rotation direction of the pressing piece 6 differs depending on whether it is the left or right storage section 5c, and by rotating one clockwise and the other counterclockwise, the locking piece 6d of the pressing piece 6 is locked onto the top of the standing piece 5h. In this way, the installation work of the pressing piece 6 to the inner lid section 5 is completed as shown in Figure 6.

[0034] As shown in FIG. 4, the compressed elastic body 7 is fixed without displacement by a fixing piece 6k 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.

[0035] Furthermore, when the pressing piece 6 is pushed into the accommodation portion 5c, a stopper piece (not shown) is present on the opposite side of the direction in which the standing piece 5h is located, so the pressing piece 6 does not rotate in the opposite direction. Furthermore, the pressing piece 6 can rotate only a predetermined angle d1 in the rotation direction, and the stopper (not shown) prevents the pressing piece 6 from rotating any further.

[0036] 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 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 the locked state as shown in Figures 1, 3, and 4. This locked state will not be released unless the unlock button 4d linked to the locking part 4b is pressed and the lid 3 is opened.

[0037] The pressing piece 6, which constantly generates a downward pressing force due to the repulsive force of the elastic body 7, presses the measuring pipe P between the base part 2b and the measuring pipe P with an appropriate pressing force from above when the measuring pipe P is placed on the base part 2b and the lid part 3 is closed and locked.

[0038] In this way, a stable pressing force can be applied by the pressing force of the elastic body 7, improving the measurement accuracy of the flowmeter and extending the life of the measuring pipe P.

[0039] 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.

[0040] When the measurement pipe P is held in this manner, the two pedestal parts 2b come into close contact with the lower part of the measurement pipe P, and ultrasonic waves are emitted alternately from the two piezoelectric vibrators 2d. The ultrasonic waves emitted from one of the piezoelectric vibrators 2d propagate through the measurement pipe P as guided waves via the acoustic matching layer 2e and the pedestal part 2b, and then enter the other piezoelectric vibrator 2d. Various data such as the propagation time of the guided wave in the measurement pipe P based on the incidence and emission of ultrasonic waves by the pair of piezoelectric vibrators 2d are transmitted to a processing device, which is an external device, via the cable 2f.

[0041] 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 of the propagation time of the obtained guided wave in the measuring pipe P and the cross-sectional area of ​​the measuring pipe P.

[0042] The measurement process of the flow velocity and flow rate of the fluid may be performed by a processing unit that is installed 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 will be transmitted to an external device via the cable 2f.

[0043] 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 inside the measurement pipe P based on the time difference in the propagation time of ultrasonic waves that propagate as guide waves using the measurement pipe P as a medium. However, it is also possible to measure the flow velocity and flow rate of the fluid by propagating ultrasonic beams from a pair of piezoelectric vibrators 2d into the fluid inside the measurement pipe P.

[0044] Fig. 8 is a perspective view of a pressing piece 6' having a pipe contacting 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 contacting surface portion 6b in Fig. 8 have different groove widths of the planar first and second groove bottom portions 6g', 6i'. Also, the inclination angles of the first and second inclined surfaces 6h, 6j of the pressing piece 6 are the same, whereas the inclination angles of the first and second inclined surfaces 6h', 6j' of the pressing piece 6' are different.

[0045] In this way, by making the groove widths of the first and second groove bottoms 6g', 6i' of the pressing piece 6' and the inclination angles of the first and second inclined surfaces 6h', 6j' different, the clamp-on mechanism 1 can hold two types of measuring tubes P with different diameters.

[0046] 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 left and right, it is possible to appropriately select the first groove portion 6e' and the second groove portion 6f' that are linear.

[0047] The curved surface of the base portion 2b on which the measurement pipe P is placed is a curved surface that fits the outer surface of the measurement pipe P to be placed, but when attaching the pressing piece 6', the curved surface of the base portion 2b is a curved surface that fits the outer surface of a measurement pipe P with a larger diameter.

[0048] Furthermore, the elastic body 7 that presses the pressing piece 6' can also be selected depending on the measurement pipe P. Considering 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 placed. 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 place an elastic body 7 with weak elasticity.

[0049] Furthermore, the pressing piece 6' does not necessarily have to hold the measurement pipe P by the elastic force of the elastic body 7. If the cross section in the groove width direction is approximately V-shaped, it is possible to hold the measurement pipe P with an appropriate amount of pressure by pressing from above with the pressing piece 6' without deforming the measurement pipe P.

[0050] Furthermore, Figures 7 and 8 illustrate pressing pieces 6, 6' that have two intersecting first and second grooves 6e, 6e', 6f, 6f' on the pipe contact surface 6b that contacts the measuring pipe P, but there may also be only one groove, as in the pair of pressing pieces 61, 62 shown in Figures 9(a) and (b).

[0051] The pressing piece 61 has only a first groove portion 6e" arranged therein compared to the pressing piece 6 shown in Figure 7, and the first groove portion 6e" is composed of a first groove bottom portion 6g" and a pair of inclined surfaces 6h" arranged on either side of the first groove bottom portion 6g".

[0052] Similarly, the pressing piece 62 has only a second groove portion 6f" arranged therein compared to the pressing piece 6 shown in Figure 7, and the second groove portion 6f" is composed of a second groove bottom portion 6i" and a pair of second inclined surfaces 6j" arranged on either side of the second groove bottom portion 6i".

[0053] The pressing pieces 61 and 62, which have the first and second groove portions 6e'', 6f'', each having a substantially V-shaped cross section in the groove width direction, are attached to the inner lid portion 5 by rotating one of them clockwise and the other counterclockwise, so that the first and second groove portions 6e'', 6f'' become linear.

[0054] In this way, the clamp-on mechanism 1 of the ultrasonic flowmeter according to the present invention can hold the measurement pipe P with an appropriate pressing strength while preventing plastic deformation of the measurement pipe P. [Explanation of symbols]

[0055] 1 Clamp-on mechanism 2 Main body 2b Base 2d piezoelectric vibrator 3 Lid 5c Storage section 5d Circular hole 5e Containment wall 5f Top part 5g Notch 5h standing piece 6, 6', 61, 62 Pressing piece 6a Cylindrical part 6b Pipe contact surface 6c bottom edge 6d locking piece 6e, 6e', 6e" First groove 6f, 6f', 6f" Second groove 6g, 6g', 6g" First groove bottom 6h, 6h', 6h" First slope 6i, 6i', 6i" Second groove bottom 6j, 6j', 6j” Second slope c center line d1 Predetermined angle d2 acute angle P measurement tube

Claims

1. A clamp-on mechanism for an ultrasonic flow meter is comprised of a main body on which a straight measuring tube is placed and a lid connected to the main body via a connecting part in an openable and closable manner, and which clamps and holds the measuring tube by closing the lid, the main body comprises a pair of pedestal parts on which the measurement pipe is placed, and a pair of ultrasonic transmitting and receiving parts that are disposed below the pair of pedestal parts and that transmit and receive ultrasonic waves to and from the measurement pipe, a pair of pressing pieces are attached to the lid portion to press the measuring tube placed on the base portion from above, A clamp-on mechanism for an ultrasonic flowmeter, characterized in that the pipe contact surface of the pressing piece has a first groove bottom that is horizontal and linear, and a first groove portion having a cross section in the groove width direction that is approximately V-shaped.

2. 2. The clamp-on mechanism of an ultrasonic flowmeter according to claim 1, wherein the pipe contact surface of the pressing piece has a second groove bottom that is horizontal and linear, intersects with the first groove, and has a substantially V-shaped cross section in the groove width direction.

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 wall portions standing from the edge portion of the circular hole portion, and a top surface portion connecting the top portions of the accommodation wall portions, 3. The clamp-on mechanism for an ultrasonic flowmeter according to claim 2, wherein the pressing piece is housed together with an elastic body in the housing portion.

4. a pair of notches that are cut outward and face the circular hole at an edge of 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 at an 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, wherein the pressing piece can be attached to the lid by inserting the cylindrical portion of the pressing piece and the locking piece into the circular hole portion and the notch 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 bottom portions is parallel to the 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 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. 7. The clamp-on mechanism of an ultrasonic flowmeter according to claim 2, wherein the groove widths of the first and second groove bottom portions and the inclination angles of the slopes arranged on both sides of the first and second groove bottom portions are different from each other.

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