Vibration transmission member, and transducer, flow velocimetry, and flow meter using the same

Abstract

To provide a vibration propagation member capable of controlling the directivity of ultrasound with a simple structure, and a transducer / receiver.SOLUTION: A vibration propagation member includes multiple partition walls 6a, 6b, 7a, 7b, 8a, and 8b each having different thicknesses arranged between a top plate 2 and a bottom plate 3. A vibrating body 16 is placed on the bottom plate 3 to form a transducer / receiver. By taking advantage of the fact that the thicker the partition wall, the faster the speed of transmission through the partition wall of the vibrating body 16, by making a difference is made in the phase of the vibrations sent out from the top plate 2. With this, wavefronts 17, 18, and 19 with different phases from top plate 2 are formed and ultrasonic waves can be transmitted in a direction perpendicular to the envelope 20.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a vibration transmitting member that operates by being joined to a vibration means, and to a transducer, a current meter, and a flow meter that use the same. [Background technology]

[0002] There is a demand in various fields for controlling the directionality of ultrasonic waves emitted from an ultrasonic transducer. Conventionally, a method for controlling the directionality of ultrasonic waves in an ultrasonic flowmeter has been known (for example, see Patent Document 1).

[0003] Fig. 6 is a schematic diagram of the ultrasonic transducer described in Patent Document 1. In Fig. 6, ultrasonic transducer 101 is composed of three rectangular vibration parts 102, 103, and 104. These vibration parts 102, 103, and 104 are composed of a piezoelectric material such as PZT or PVDF.

[0004] Electrodes 102a, 103a, 104a are formed on the upper portions of the vibrating portions 102, 103, 104, respectively. Electrodes 102b, 103b, 103c (not shown), such as baked silver electrodes, are also formed on the lower portions of the vibrating portions 102, 103, 104, respectively. Driving power sources 102c, 103c, 104c, which can independently supply power, are connected to the electrodes via lead wires 102d, 103d, 104d and lead wires 102e, 103e, 104e.

[0005] In such a configuration, by using three independent driving power sources 102c, 103c, and 104c to sequentially drive the three vibration parts 102, 103, and 104 with a phase difference of within half a wavelength, the spatial intensity distribution can be freely shifted in any direction from the reference axis of the overall ultrasonic transmission direction, thereby controlling the directionality. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-26342 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional configuration in Patent Document 1 required multiple vibration parts 102, 103, and 104, and individual driving power sources 102c, 103c, and 104c for each of them, which had the problem of increasing the number of components and making the configuration complicated.

[0008] The present invention addresses the above-mentioned problems, and aims to control the directionality of ultrasound with a small number of parts by forming multiple membrane structures in a vibration propagation member, generating a phase difference in the vibration of the multiple membrane structures, and making it possible to set the direction of ultrasound propagation to any angle using the phase difference. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the vibration propagation member of the present invention is a vibration propagation member that is joined to one surface of a vibrating body and operates, and is formed of a top plate, a side wall, and a partition wall disposed approximately perpendicular to the top plate, and uses vibrations generated in a plurality of film structures formed by the top plate and the partition wall, and generates a phase difference in the vibrations of the plurality of film structures by changing the thickness of the partition wall. Furthermore, by using the phase difference, the direction of propagation of the ultrasound waves emitted from the multiple membrane structures can be set to any angle relative to the top plate, thereby enabling ultrasonic directionality control with a small number of parts. Effect of the Invention

[0010] The vibration propagation member of the present invention allows the direction of ultrasonic waves to be set at any angle, thereby enabling the directionality of ultrasonic waves to be controlled with a small number of parts. Also, by joining a vibrator to the vibration propagation member and using it as an ultrasonic transmitter / receiver in an ultrasonic flowmeter, it becomes possible to mount the transmitting / receiving surface of the ultrasonic transmitter / receiver flush with the pipe wall of the flow path through which the measured fluid flows, thereby enabling the construction of a flowmeter with fewer errors. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an exploded perspective view of a vibration propagation member according to a first embodiment of the present invention; [Diagram 2] 1 is a cross-sectional view of a vibration propagation member according to a first embodiment of the present invention; [Diagram 3] FIG. 1 is a diagram showing a method for forming a vibration propagation member in accordance with the first embodiment of the present invention. [Figure 4] FIG. 11 is a cross-sectional view of a transducer according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is a configuration diagram of an ultrasonic flowmeter according to a third embodiment of the present invention. [Figure 6] Schematic diagram of a conventional ultrasonic transducer DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The first invention is a vibration propagation member that operates by being joined to one surface of a vibrating body, and is formed of a top plate, a side wall, and a partition wall arranged approximately perpendicular to the top plate.The vibration generated in multiple membrane structures formed by the top plate and the partition wall is used, and a phase difference is generated in the vibration of the multiple membrane structures by changing the thickness of the partition wall.By using this phase difference, the propagation direction of the ultrasound waves emitted from the multiple membrane structures can be set to any angle relative to the top plate, thereby enabling directionality of the ultrasound to be controlled with a single vibration propagation member.

[0013] A second invention is particularly characterized in that, in the first invention, the partition walls have a thickness that gradually changes.

[0014] The third invention is a transmitter / receiver comprising a vibrating body and a vibration propagation member of the first or second invention joined to one surface of the vibrating body, thereby making it possible to control the directionality of ultrasound using one vibrating body and one vibration propagation member.

[0015] The fourth invention comprises a flow path through which the fluid to be measured flows, a pair of transmitters and receivers of the third invention attached upstream and downstream of the flow path, a timing device which measures the propagation time of ultrasonic waves between the transmitters and receivers, and a calculation unit which calculates the flow velocity and flow rate of the fluid to be measured from the propagation time determined by the timing device.This makes it possible to install the transmitting and receiving surface of the ultrasonic transmitter and receiver flush with the pipe wall of the flow path through which the fluid to be measured flows, thereby enabling the construction of a flow meter with little error.

[0016] Hereinafter, the embodiments will be described in detail with reference to the drawings. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming more redundant than necessary and to facilitate understanding by those skilled in the art.

[0017] It should be noted that the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0018] (Embodiment 1) The first embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0019] Fig. 1 is an exploded perspective view of a vibration propagation member according to the first embodiment of the present invention. As shown in Fig. 1, the vibration propagation member 1 is configured in a space surrounded by a top plate 2, a bottom plate 3, and side walls 4 and 5, and includes a plurality of partition walls 6a, 6b, 7a, 7b, 8a, and 8b arranged substantially perpendicular to the top plate 2 and the bottom plate 3.

[0020] 1, in order to make it easier to understand the internal structure of the vibration propagation member 1, the bottom plate 3 and the side wall 5 are removed. With this configuration, the top plate 2 is divided into a membrane surface 9 partitioned by partitions 6a and 6b, a membrane surface 10 partitioned by partitions 7a and 7b, and a membrane surface 11 partitioned by partitions 8a and 8b.

[0021] Figure 2 shows a cross section of the vibration propagation member 1 in Figure 1. Figure 2(a) is a horizontal cross section taken along line AA' in Figure 1, and Figure 2(b) is a vertical cross section taken along line BB' in Figure 1. As shown in Figure 2(a), the lengths (Ma, Mb, Mc) of film surface 9, film surface 10, and film surface 11 are approximately equal, and their widths (W) are constant.

[0022] On the other hand, as shown in FIG. 2(b), the heights H of the partition walls 6a, 6b, the partition walls 7a, 7b, and the partition walls 8a, 8b are equal to each other, but the thicknesses La of the partition walls 6a, 6b, the thicknesses Lb of the partition walls 7a, 7b, and the thicknesses Lc of the partition walls 8a, 8b are set to have the following relationship:

[0023] La > Lb > Lc As a result, the vibration propagation member 1 has vibrating portions made up of three membrane structures (each shown by dotted lines): membrane structure 12 made up of partitions 6a, 6b and membrane surface 9; membrane structure 13 made up of partitions 7a, 7b and membrane surface 10; and membrane structure 14 made up of partitions 8a, 8b and membrane surface 11.

[0024] The resonance frequencies of these membrane structures 12, 13, 14 may be slightly affected by the thicknesses La, Lb, Lc of the partition walls, but in that case, fine adjustments can be made by adjusting the lengths Ma, Mb, Mc of the membrane surfaces.

[0025] In FIG. 1, vibration propagation member 1 is shown as being composed of top plate 2, bottom plate 3, side walls 4 and 5, and partitions 6a, 6b, 7a, 7b, 8a, 8b, each of which is a separate member. However, as shown in FIG. 3, vibration propagation member 51 can also be formed by laminating multiple intermediate plates 54, which are made by etching a thin metal (e.g., SUS) plate into a predetermined shape, to form the partitions and side walls, and further laminating top plate 52 and bottom plate 53 above and below them.

[0026] The operation of this vibration propagating member will be described in the next section on the operation of the second embodiment.

[0027] (Embodiment 2) The second embodiment will be described with reference to FIG.

[0028] Fig. 4 shows a cross-sectional view of the transducer 15. The transducer 15 is configured by attaching a vibrating body 16 to the bottom plate 3 of the vibration propagation member 1 described in the first embodiment. The vibrating body 16 is, for example, a piezoelectric body. The vibration propagation member 1 is the same as in the first embodiment, so the same reference numbers are used for the same parts as in Figs. 1 and 2.

[0029] Next, the operation of this transducer will be explained with reference to FIG.

[0030] Now, when vibrations having a certain frequency are supplied from the vibrating body 16 through the bottom plate 3, the vibration are transmitted to the top plate 2 via the partitions 6a and 6b, 7a and 7b, and 8a and 8b, respectively. That is, the vibrations are transmitted to the top plate 2 via the membrane structures 12, 13, and 14 shown in FIG. 2(b). At this time, since the thicknesses of the partitions are different as mentioned above, the speed at which the vibration waves propagate through the partitions changes due to the plate wave effect of the vibration waves. The greater the wall thickness, the greater the propagation speed. Therefore, the vibrations propagating through the partitions 6a and 6b, which are the thickest among these partitions, reach the membrane surface 9 the fastest.

[0031] Next, the vibration propagating through the partitions 7a and 7b propagates to the membrane surface 10. Finally, the vibration propagating through the partitions 8a and 8b propagates to the membrane surface 11.

[0032] Therefore, membrane surface 9 composed of membrane structure 12, membrane surface 10 composed of membrane structure 13, and membrane surface 11 composed of membrane structure 14 will vibrate in sequence due to the vibration supplied from vibrating body 16, and as a result, a time difference (phase difference) will be generated in the ultrasonic waves emitted from membrane surfaces 9, 10, and 11.

[0033] At a certain moment, the arc-shaped wavefronts 17, 18, and 19 respectively indicate the state of the leading wavefront of the ultrasonic waves emitted from the film surfaces 9, 10, and 11. A thick arrow U perpendicular to the envelope 20 of the wavefronts 17, 18, and 19 indicates the propagation direction of the entire ultrasonic waves emitted from the tabletop 2.

[0034] The above is the case where the transducer 15 is used for transmitting ultrasonic waves, but even when it is used for receiving waves, the relationship between the thickness of the partition and the propagation speed does not change, so it is sufficient to consider the phase difference due to the thickness. In other words, in Fig. 4, the vibration phase in the vibrating body 16 can be aligned by setting the order of the membrane surfaces 11, 10, and 9 as the arrival time order of the ultrasonic waves to the membrane surfaces. When the transducer 15 is used as a pair of transducers, as shown in Fig. 5, the transducers are arranged with their left and right directions reversed, so that the ultrasonic waves transmitted from one transducer (ultrasonic transducer 23) can be received by the other transducer (ultrasonic transducer 24). Details will be described in the third embodiment.

[0035] In FIG. 2(a), there are portions of widths N1 and N2 between partitions 6b and 7a, and between partitions 7b and 8a. However, if these widths are made sufficiently smaller than the lengths Ma, Mc, Mc of film surfaces 9, 10, and 11, respectively, the wavefronts transmitted from these portions can be ignored.

[0036] As described above, by controlling the thickness of the partition, the speed of vibration propagating through the partition can be controlled, and as a result, the directivity of the ultrasonic waves emitted from the tabletop can be controlled. In other words, the inclination angle α of the ultrasonic wave propagation direction (arrow U) with respect to the tabletop 2 can be controlled.

[0037] (Embodiment 3) The third embodiment will be described with reference to FIG.

[0038] 5 shows a cross-sectional view of an ultrasonic flowmeter 21 according to a third embodiment of the present invention. A flow path 22 is a passage through which the fluid to be measured flows, and one ultrasonic transmitter / receiver 23 is provided on the upstream side of the flow path 22, and the other ultrasonic transmitter / receiver 24 is provided on the downstream side of the flow path 22. The transmitter / receiver described in the second embodiment is used as the pair of ultrasonic transmitter / receivers 23, 24. A timing device 25 measures the propagation time of ultrasonic waves between the ultrasonic transmitter / receivers 24, 25. A calculation unit 26 calculates the flow velocity and flow rate of the fluid to be measured based on the propagation time measured by the timing device 25.

[0039] The arrows in the figure indicate the direction of fluid flow, V indicates the fluid flow velocity, and L indicates the distance between the ultrasonic transmitter and receiver. The angle θ indicates the intersection angle between the direction of fluid flow and the direction of ultrasonic propagation between the ultrasonic transmitter and receiver.

[0040] In this case, the ultrasonic transmitter / receiver 23 in the flow path 22 is arranged and configured so that the direction of ultrasonic waves travels at an angle θ with respect to the flow direction. That is, the arrangement and configuration are such that the angle α in Fig. 4 becomes the angle θ. On the other hand, the ultrasonic transmitter / receiver 24 has the same configuration as the ultrasonic transmitter / receiver 23, and is arranged so as to face the ultrasonic transmitter / receiver 24, with the left and right reversed with respect to the flow direction.

[0041] The operation of the ultrasonic flowmeter 21 configured as above will be briefly described. One ultrasonic transmitter / receiver 23 is operated as an ultrasonic transmitter, and the other ultrasonic transmitter / receiver 24 is operated as an ultrasonic receiver. If the propagation time of ultrasonic waves from the ultrasonic transmitter / receiver 23 to 24 is Tud, and the propagation time of ultrasonic waves from the ultrasonic transmitter / receiver 24 to 23 is Tdu, the flow velocity V can be calculated by the following equation using the propagation time reciprocal difference method.

[0042] V =[L / 2cosθ]·[(1 / Tud)-(1 / Tdu)] (1) From formula (1), if the distance L between the ultrasonic transmitter and receiver and the crossing angle θ are known, the flow velocity V can be obtained by measuring the propagation times Tud and Tdu with the timing device 25. By multiplying this flow velocity V by the flow path cross-sectional area S of the flow path 22 and the correction coefficient k using the calculation unit 26, the flow rate Q can be obtained by the following formula.

[0043] Q = k S V (2) In this way, the flow velocity V and flow rate Q of the fluid can be measured, functioning as a flow meter or flow meter.

[0044] In the ultrasonic flowmeter shown in the third embodiment, ultrasonic waves can be emitted at an angle θ with respect to the ultrasonic transmission surface of the ultrasonic transmitter / receiver, so that the ultrasonic transmission surface can be made flush with the inner wall surface of the flow path 22. Therefore, it is not necessary to mount the ultrasonic transmitter / receiver at an angle to the flow as in the conventional method, and it is possible to eliminate the recessed portion that was generated in front of the ultrasonic transmitter / receiver (for example, see FIG. 7 of the publication shown as Patent Document 1). Therefore, the generation of vortexes due to the recessed portion is eliminated, and highly accurate flow measurement with few errors is possible. [Industrial Applicability]

[0045] As described above, the vibration propagation member of the present invention is configured to have multiple membrane structures in the vibration propagation member, generates a phase difference in the vibration of the multiple membrane structures, and makes it possible to set the direction of propagation of the ultrasonic waves to any angle using the phase difference, thereby enabling directional control of the ultrasonic waves to be performed with a small number of parts.

[0046] Furthermore, by attaching a piezoelectric body to the vibration propagation member and applying it to an ultrasonic flowmeter as an ultrasonic transmitter / receiver, a flowmeter with little error can be constructed in which the ultrasonic transmitter / receiver is installed flush with the pipe wall. This means that the device can be widely used for flow measurement that requires precision, such as various ultrasonic flowmeters and their application products, such as gas meters and water meters. [Explanation of symbols]

[0047] 1, 51 Vibration transmission member 2, 52 Tabletop 3, 53 bottom plate 4, 5 side wall 6a, 6b bulkhead 7a, 7b bulkhead 8a, 8b bulkhead 12, 13, 14 Membrane structure 15 Transmitter / Receiver 16 Vibration body 21 Ultrasonic flowmeter (current meter, flowmeter) 22 Flow Path 23, 24 Ultrasonic transducer (transmitter) 25 Timing device 26 Arithmetic section 54 Intermediate plate (side wall, bulkhead)

Claims

1. A vibration transmission member that operates by being joined to one surface of a vibrating body, A vibration propagation member formed of a top plate, side walls, and a partition wall arranged approximately perpendicular to the top plate, which uses vibrations generated in multiple membrane structures formed by the top plate and the partition wall, and by making the thicknesses of the partition wall different, generates a phase difference in the vibrations of the multiple membrane structures, and by using the phase difference, the propagation direction of ultrasound emitted from the multiple membrane structures can be set to any angle with respect to the top plate.

2. 2. The vibration propagation member according to claim 1, wherein the partition walls have thicknesses which vary from one another.

3. 3. A transducer comprising: a vibrating body; and the vibration propagation member according to claim 1 or 2 bonded to one surface of the vibrating body.

4. a flow path through which a fluid to be measured flows; A pair of transducers according to claim 3 attached to the upstream and downstream of the flow path; A timing device that measures the propagation time of ultrasonic waves between the transducers; a calculation unit that calculates a flow velocity and a flow rate of the fluid to be measured from the propagation time obtained by the timing device; A flow meter comprising:

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