Wiring structure and ultrasonic flowmeter

Abstract

To provide a wiring structure capable of suppressing transmission of vibration noise to wiring by appropriately routing and fixing the wiring.SOLUTION: A wiring structure is provided, comprising: a metal plate 41 having a piezoelectric element 42 mounted thereon; a packing 45 provided in a case member 20, the packing having a wiring holding portion 54 for holding wiring 44 connected to the metal plate 41 and the piezoelectric element 42; and a cap 30 for pressing down on the wiring holding portion 54 holding the wiring 44. The wiring 44 is covered with a packing material forming the wiring holding portion 54.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a wiring structure and an ultrasonic flowmeter.

Background Art

[0002] Patent Document 1 discloses a piezoelectric device. The piezoelectric device disclosed in Patent Document 1 has a wiring structure in which a piezoelectric element and wiring connected to a metal plate to which the piezoelectric element is attached are embedded inside a vibration damping member formed of a resin material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the wiring structure disclosed in Patent Document 1, when forming the vibration damping member, the wiring is arranged in advance in a state of being connected to the piezoelectric element and the metal plate in the mold used for the molding, so that the wiring is embedded inside the vibration damping member together with the molding of the vibration damping member. Therefore, in the wiring structure disclosed in Patent Document 1, it is difficult to route the wiring to a predetermined position in the mold. If the wiring cannot be routed appropriately, there is a risk that the vibration noise of the piezoelectric element will propagate to the wiring.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a wiring structure capable of appropriately routing and fixing the wiring and suppressing the propagation of vibration noise to the wiring.

Means for Solving the Problems

[0006] The wiring structure according to the present disclosure includes a metal plate to which a piezoelectric element is attached, a packing having a wiring holding portion provided in a housing and holding wirings connected to the piezoelectric element and the metal plate, and a pressing member that presses the wiring holding portion holding the wirings. The periphery of the wiring is covered by the packing material forming the wiring holding portion, or the packing material forming the wiring holding portion and the pressing member.

Advantages of the Invention

[0007] According to the present disclosure, the wiring can be properly routed and fixed, and the propagation of vibration noise to the wiring can be suppressed.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] Embodiment 1. The wiring structure according to Embodiment 1 will be described with reference to FIGS. 1 to 5.

[0011] First, the configuration of the ultrasonic flowmeter 100 according to Embodiment 1 will be described with reference to FIGS. 1 to 3. FIG. 1 is an external perspective view of the ultrasonic flowmeter 100 to which the piezoelectric devices 40a and 40b according to Embodiment 1 are applied. FIG. 2 is a diagram showing a state where the piezoelectric devices 40a and 40b according to Embodiment 1 are attached to the case members 20a and 20b. FIG. 3 is a plan view of the case members 20a and 20b. In FIG. 1, the upstream wiring 44 and the downstream cap 30b are removed.

[0012] The ultrasonic flowmeter 100 shown in Fig. 1 measures the flow rate or flow velocity of a fluid using ultrasonic waves. The fluid to be measured is a gas such as air or gas, or a liquid such as water. The ultrasonic flowmeter 100 is mounted on, for example, a gas meter or a water meter. The arrow shown in Fig. 1 indicates the flow direction of the fluid passing through the inside of the ultrasonic flowmeter 100.

[0013] As shown in Fig. 1, the ultrasonic flowmeter 100 includes a single measurement tube 10, a pair of case members 20a, 20b, a pair of caps 30a, 30b, and a pair of piezoelectric devices 40a, 40b. The measurement tube 10 and the case members 20a, 20b constitute the housing of the ultrasonic flowmeter 100.

[0014] The measurement tube 10 has a cylindrical shape. The measurement tube 10 has a measurement flow path 11, an inlet 12, and an outlet 13. The measurement tube 10 is formed of, for example, a resin material. The measurement flow path 11, the inlet 12, and the outlet 13 are integrally formed.

[0015] The measurement flow path 11 is constituted by the inner peripheral surface of the measurement tube 10 and is formed along the axial direction of the measurement tube 10. The fluid flows along the axial direction of the measurement flow path 11. The upstream opening end of the measurement flow path 11 constitutes the inlet 12 through which the fluid flows in. On the other hand, the downstream opening end of the measurement flow path 11 constitutes the outlet 13 through which the fluid flows out. That is, the measurement tube 10 passes the fluid supplied into the measurement flow path 11 from the inlet 12 through the measurement flow path 11 and then discharges it from the outlet 13. Although details will be described later, the ultrasonic flowmeter 100 measures the flow rate or flow velocity of the fluid when the fluid passes through the measurement flow path 11.

[0016] As shown in FIGS. 1 to 3, the case members 20a and 20b are members for attaching the piezoelectric devices 40a and 40b to the measurement pipe 10. The case members 20a and 20b are provided along the axial direction (fluid flow direction) of the measurement flow path 11 on the upper surface that is the same surface in the measurement pipe 10. One case member 20a is disposed on the upstream side of the measurement flow path 11. The other case member 20b is disposed on the downstream side of the measurement flow path 11.

[0017] The case members 20a and 20b are formed of, for example, a resin material. The case members 20a and 20b may be integrally formed with the measurement pipe 10 or may be separate from the measurement pipe 10.

[0018] The case members 20a and 20b have an annular bottom plate 21 and a vertical wall 22 provided on the outer peripheral portion of the bottom plate 21. Thus, the case members 20a and 20b are box-shaped with an open upper side. For this reason, the case members 20a and 20b can accommodate and attach the piezoelectric devices 40a and 40b therein. The case members 20a and 20b are arranged such that their central axes are inclined with respect to the axial direction of the measurement flow path 11. The vertical wall 22 has a notch-shaped passage port 22a for wiring.

[0019] As shown in FIGS. 1 and 2, the caps 30a and 30b can be attached to the respective vertical walls 22 of the case members 20a and 20b as covers for protecting the piezoelectric devices 40a and 40b. The caps 30a and 30b are formed of, for example, a resin material. The caps 30a and 30b constitute pressing members.

[0020] As shown in FIGS. 1 to 3, the piezoelectric devices 40a and 40b are, for example, ultrasonic sensors or ultrasonic vibration elements that generate ultrasonic waves. The piezoelectric devices 40a and 40b can transmit and receive ultrasonic waves to and from each other. One piezoelectric device 40a functions as an ultrasonic oscillator and receiver. The other piezoelectric device 40b functions as an ultrasonic receiver and transmitter.

[0021] Piezoelectric devices 40a and 40b are provided along the axial direction of the measurement flow path 11. The piezoelectric devices 40a and 40b are attached inside the case members 20a and 20b. That is, one piezoelectric device 40a disposed on the upstream side of the measurement flow path 11 is attached inside the case member 20a. Further, the other piezoelectric device 40b disposed on the downstream side of the measurement flow path 11 is attached inside the case member 20b.

[0022] In this way, the piezoelectric devices 40a and 40b are attached inside the case members 20a and 20b, so that their central axes are inclined with respect to the axial direction of the measurement flow path 11 and are arranged to face the measurement flow path 11. Specifically, the piezoelectric device 40a is disposed obliquely so that its transmission / reception surface faces the downstream side. Further, the piezoelectric device 40b is disposed obliquely so that its transmission / reception surface faces the upstream side. Furthermore, when the piezoelectric devices 40a and 40b are attached inside the case members 20a and 20b, their peripheries will be surrounded by the vertical wall 22, but they do not protrude above the upper end of the vertical wall 22.

[0023] Here, the ultrasonic flowmeter 100 propagates the ultrasonic waves transmitted from the piezoelectric devices 40a and 40b into the fluid flowing through the measurement flow path 11. Then, the ultrasonic flowmeter 100 measures the flow rate or flow velocity of the fluid flowing through the measurement flow path 11 based on the propagation time difference of the ultrasonic waves between the piezoelectric devices 40a and 40b.

[0024] Specifically, the ultrasonic wave transmitted from the piezoelectric device 40a obliquely propagates from the upstream side to the downstream side in the fluid flowing through the measurement channel 11, reflects off the bottom surface of the measurement channel 11, and is then received by the piezoelectric device 40b. On the other hand, the ultrasonic wave transmitted from the piezoelectric device 40b obliquely propagates from the downstream side to the upstream side in the fluid flowing through the measurement channel 11, reflects off the bottom surface of the measurement channel 11, and is then received by the piezoelectric device 40a. That is, the propagation paths of both ultrasonic waves are each formed in a V shape. And the ultrasonic flowmeter 100 obtains the propagation times of the ultrasonic waves in two directions respectively when the piezoelectric devices 40a and 40b transmit and receive ultrasonic waves, and then measures the flow rate or flow velocity of the fluid flowing through the measurement channel 11 based on the propagation time difference between them.

[0025] Next, the configuration of the piezoelectric devices 40a and 40b will be described with reference to FIG. 4. FIG. 4 is an external perspective view of the piezoelectric device 40 according to Embodiment 1. Since the piezoelectric devices 40a and 40b have the same configuration and the same functions, in the following description, the piezoelectric devices 40a and 40b are described as the piezoelectric device 40.

[0026] As shown in FIG. 4, the piezoelectric device 40 is circular as a whole. The piezoelectric device 40 has a metal plate 41, a piezoelectric element 42, an acoustic matching layer 43, a wiring 44, and a packing 45.

[0027] The metal plate 41 is flat and circularly formed. This metal plate 41 serves as a diaphragm. The metal plate 41 has an upper surface 41a and a lower surface 41b. The upper surface 41a and the lower surface 41b are arranged on opposite sides in the thickness direction of the metal plate 41. The metal plate 41 is formed of a metal material such as stainless steel, aluminum, or copper, for example.

[0028] When the piezoelectric device 40 is attached to the case members 20a and 20b, the upper surface 41a is disposed on the opening side of the case members 20a and 20b. This upper surface 41a is a surface for attaching the piezoelectric element 42. When the piezoelectric device 40 is attached to the case members 20a and 20b, the lower surface 41b faces the bottom plate 21 of the case members 20a and 20b. This lower surface 41b is a surface for attaching the acoustic matching layer 43.

[0029] Note that the metal plate 41 constitutes a mounting plate. The upper surface 41a constitutes the first surface. The lower surface 41b constitutes the second surface.

[0030] The piezoelectric element 42 can mutually convert an ultrasonic signal, which is an electrical signal, and ultrasonic waves. Also, the piezoelectric element 42 can transmit and receive ultrasonic waves. Specifically, when a voltage is applied, the piezoelectric element 42 expands and contracts (vibrates) in the thickness direction of the metal plate 41 to generate ultrasonic waves. Also, when ultrasonic waves (vibrations) are applied from the outside, the piezoelectric element 42 generates a voltage. The piezoelectric element 42 is attached to the upper surface 41a of the metal plate 41 via, for example, an adhesive.

[0031] The acoustic matching layer 43 improves the efficiency of transmission and reception of ultrasonic waves in the piezoelectric element 42. This acoustic matching layer 43 matches the acoustic impedance of the piezoelectric element 42 and the acoustic impedance of the fluid, and suppresses reflection of ultrasonic waves therebetween. For this reason, the acoustic matching layer 43 is attached to the lower surface 41b facing the measurement channel 11.

[0032] Therefore, the ultrasonic waves generated by the piezoelectric element 42 are emitted from the acoustic matching layer 43 to the measurement channel 11 through the metal plate 41. On the other hand, the ultrasonic waves incident on the acoustic matching layer 43 from the measurement channel 11 are propagated to the piezoelectric element 42 through the metal plate 41.

[0033] The two wirings 44 are respectively connected to the upper surface 41a of the metal plate 41 and the surface of the piezoelectric element 42. These wirings 44 are drawn from the piezoelectric device 40 mounted inside the case members 20a and 20b through the through-hole 22a of the vertical wall 22 to a control device (not shown) provided in the ultrasonic flowmeter 100.

[0034] Specifically, one end of one wiring 44 is connected to the upper surface 41a of the metal plate 41, and the other end of the wiring 44 is connected to a control device (not shown) provided in the ultrasonic flowmeter 100. Also, one end of the other wiring 44 is connected to the surface of the piezoelectric element 42, and the other end of the wiring 44 is connected to the above control device.

[0035] The packing 45 is designed to achieve both the fixation of the piezoelectric device 40 to the case members 20a and 20b and the suppression of the attenuation of the ultrasonic vibration generated by the piezoelectric element 42. In this way, the ultrasonic flowmeter 100 can suppress the vibration transmitted from the piezoelectric device 40 to the measurement pipe 10 through the case members 20a and 20b by fixing the piezoelectric device 40 to the case members 20a and 20b via the packing 45. Therefore, the ultrasonic flowmeter 100 can suppress the decrease in measurement accuracy.

[0036] The packing 45 has a main body 51, an outer peripheral wall portion 52, a notch portion 53, a wiring holding portion 54, and an insertion groove 55. The packing 45 is formed of, for example, an elastic resin material which is a packing material. The main body 51, the outer peripheral wall portion 52, the notch portion 53, the wiring holding portion 54, and the insertion groove 55 are integrally formed.

[0037] The main body 51 is annular. The outer peripheral wall portion 52 is provided along the circumferential direction at the outer peripheral portion of the upper surface of the main body 51. The notch portions 53 are respectively formed at a plurality of positions on the outer peripheral wall portion 52 so as to notch the outer peripheral wall portion 52. FIGS. 6 and 7 show an example in which three notch portions 53 are formed for one outer peripheral wall portion 52. One or more notch portions 53 may be formed.

[0038] The wiring holding portion 54 holds two wirings 44. The wiring holding portion 54 is formed so as to protrude radially outward from the outer peripheral surface of the outer peripheral wall portion 52. Further, the wiring holding portion 54 is formed so as to be continuous with the outer peripheral wall portions 52 on both sides in the radial direction. Although details of this wiring holding portion 54 will be described later, the lower ends of the caps 30a and 30b attached to the case members 20a and 20b can be pressed against the upper surface of the wiring holding portion 54.

[0039] The insertion groove 55 is a groove into which the outer peripheral portion of the metal plate 41 is inserted. A plurality of insertion grooves 55 are provided on the inner side in the radial direction of the outer peripheral wall portion 52. The insertion grooves 55 are arranged at a predetermined interval in the radial direction. FIG. 4 shows an example in which four insertion grooves 55 are formed.

[0040] Next, the wiring structure according to Embodiment 1 will be described with reference to FIG. 5. FIG. 5 is a front view of the wiring structure according to Embodiment 1. Since the case members 20a and 20b and the caps 30a and 30b have the same configuration and the same functions, in the following description, the case members 20a and 20b are described as the case member 20, and the caps 30a and 30b are described as the cap 30.

[0041] As shown in FIG. 5A, the wiring holding portion 54 of the packing 45 has a wiring holding groove 54a that is a bottomed groove. The wiring 44 routed from the metal plate 41 and the piezoelectric element 42 can be inserted into the wiring holding groove 54a. At this time, the groove width of the wiring holding groove 54a is longer than the diameter of the wiring 44. Therefore, in the wiring holding portion 54, the wiring 44 can be easily inserted into the wiring holding groove 54a.

[0042] Then, as shown in FIG. 5B, when the cap 30 is attached to the vertical wall 22 of the case member 20, the cap 30 presses and crushes the wiring holding portion 54. For this reason, the wiring holding groove 54a is filled with the packing material. As a result, the wiring holding groove 54a can cover the periphery of the wiring 44 by being pressed by the cap 30 with the wiring 44 inserted therein. Thus, since the periphery of the wiring 44 is covered with the packing material and fixed, vibration noise from the piezoelectric element 42 is suppressed.

[0043] As described above, the wiring structure according to Embodiment 1 can appropriately route and fix the wiring 44 and suppress the propagation of vibration noise from the piezoelectric element 42 to the wiring 44.

[0044] Embodiment 2. The wiring structure according to Embodiment 2 will be described with reference to FIG. 6. FIG. 6 is a front view of the wiring structure according to Embodiment 2. Note that components having the same functions as those described in Embodiment 1 above are denoted by the same reference numerals, and the description thereof is omitted.

[0045] As shown in FIG. 6A, the wiring holding portion 54 of the packing 45 has a wiring holding groove 54b that is a bottomed groove. The wiring 44 routed from the metal plate 41 and the piezoelectric element 42 can be inserted into the wiring holding groove 54b. At this time, although the groove width of the wiring holding groove 54a is shorter than the diameter of the wiring 44, in the wiring holding portion 54 using an elastic resin material as the packing material, the wiring 44 can be easily inserted into the wiring holding groove 54b.

[0046] Then, as shown in FIG. 6B, when the cap 30 is attached to the vertical wall 22 of the case member 20, the cap 30 presses and crushes the wiring holding portion 54. For this reason, the wiring holding groove 54b is filled with the packing material. As a result, the wiring holding groove 54b can cover the periphery of the wiring 44 by being pressed by the cap 30 with the wiring 44 inserted therein.

[0047] At this time, since the groove width of the wiring holding groove 54b is shorter than the diameter of the wiring 44, the wiring holding groove 54b can be easily filled with the packing material. Therefore, the periphery of the wiring 44 is covered without gaps by the packing material. In this way, since the wiring 44 is fixed by having its periphery covered with the packing material, vibration noise from the piezoelectric element 42 is suppressed.

[0048] As described above, the wiring structure according to the second embodiment can appropriately route and fix the wiring 44, and suppress the propagation of vibration noise from the piezoelectric element 42 to the wiring 44.

[0049] Embodiment 3. The wiring structure according to Embodiment 3 will be described with reference to FIG. 7. FIG. 7 is a front view of the wiring structure according to Embodiment 3. Note that components having the same functions as those described in Embodiment 1 described above are denoted by the same reference numerals, and the description thereof is omitted.

[0050] As shown in FIG. 7A, the cap 30 has a wiring recess 31. The wiring recess 31 is provided at the lower end of the cap 30. The wiring recess 31 enables the outer peripheral surface of the wiring 44 to be fitted therein. For example, the wiring recess 31 enables the circumferential half of the outer peripheral surface of the wiring 44 to be fitted therein. In this case, the wiring recess 31 has a semi-circular shape.

[0051] Then, as shown in FIG. 7B, when the cap 30 is attached to the vertical wall 22 of the case member 20, the circumferential half portion of the outer peripheral surface of the wiring 44 is fitted into the wiring recess 31, and then the other circumferential half portion of the outer peripheral surface of the wiring 44 is embedded in the wiring holding portion 54. That is, the wiring holding portion 54 deforms so as to sink the portion of the wiring 44 that is not fitted into the wiring recess 31. As a result, the wiring 44 is covered by the packing material and the cap 30. In this way, since the wiring 44 is fixed by having its periphery covered with the packing material and the wiring recess 31 of the cap 30, vibration noise from the piezoelectric element 42 is suppressed.

[0052] As described above, the wiring structure according to Embodiment 3 can appropriately route and fix the wiring 44, and suppress the propagation of vibration noise from the piezoelectric element 42 to the wiring 44.

[0053] Embodiment 4. The wiring structure according to Embodiment 4 will be described with reference to FIG. 8. FIG. 8 is a front view of the wiring structure according to Embodiment 4. For components having the same functions as those described in Embodiment 1 above, the same reference numerals are used, and the description thereof is omitted.

[0054] As shown in FIG. 8A, the wiring holding portion 54 of the packing 45 has a wiring holding groove 54c that serves as a through groove. The wiring 44 routed from the metal plate 41 and the piezoelectric element 42 can be inserted into the wiring holding groove 54c. As shown in FIG. 8B, the case member 20 has a fitting recess 23. The fitting recess 23 can fit the wiring holding portion 54 with the wiring 44 inserted into the wiring holding groove 54c.

[0055] Then, as shown in FIG. 8C, when the wiring holding portion 54 with the wiring 44 inserted into the wiring holding groove 54c is fitted to the fitting recess 23, the wiring holding portion 54 deforms such that the wiring holding groove 54c is crushed in the groove width direction. For this reason, the wiring holding groove 54c is filled with the packing material. As a result, the wiring holding groove 54c can cover the periphery of the wiring 44 by being crushed by the fitting recess 23 with the wiring 44 inserted therein by the packing material. In this way, since the wiring 44 is fixed by having its periphery covered with the packing material, vibration noise from the piezoelectric element 42 is suppressed.

[0056] As described above, the wiring structure according to Embodiment 4 can appropriately route and fix the wiring 44, and suppress the propagation of vibration noise from the piezoelectric element 42 to the wiring 44.

[0057] Embodiment 5. The wiring structure according to Embodiment 5 will be described with reference to FIG. 9. FIG. 9 is a front view of the wiring structure according to Embodiment 5. For components having the same functions as those described in Embodiment 1 above, the same reference numerals are given and the description thereof is omitted.

[0058] As shown in FIG. 9A, the wiring holding portion 54 of the packing 45 has a slit 54d. The wiring 44 routed from the metal plate 41 and the piezoelectric element 42 can be inserted into the wiring holding groove 54a. At this time, as shown in FIG. 9B, when the wiring 44 is pushed into the inside of the slit 54d, the periphery of the wiring 44 is covered with a packing material. In this way, since the wiring 44 is fixed by having its periphery covered with a packing material, vibration noise from the piezoelectric element 42 is suppressed.

[0059] As described above, the wiring structure according to Embodiment 5 can appropriately route and fix the wiring 44 and suppress the propagation of vibration noise from the piezoelectric element 42 to the wiring 44.

[0060] Note that within the scope of the present disclosure, any component of the embodiment can be modified or any component of the embodiment can be omitted.

Description of Reference Numerals

[0061] 10 Measuring tube, 11 Measuring flow path, 12 Inlet, 13 Outlet, 20, 20a, 20b Case member, 21 Bottom plate, 22 Vertical wall, 22a Passage port, 23 Fitting recess, 30, 30a, 30b Cap, 31 Wiring recess, 40, 40a, 40b Piezoelectric device, 41 Metal plate, 41a Upper surface, 41b Lower surface, 42 Piezoelectric element, 43 Acoustic matching layer, 44 Wiring, 45 Packing, 51 Main body, 52 Outer peripheral wall portion, 54 Wiring holding portion, 54a to 54c Wiring holding grooves, 54d Wiring slit, 55 Insertion groove, 100 Ultrasonic flowmeter.

Claims

1. A metal plate to which a piezoelectric element is attached, a packing provided in a housing and having a wiring holding portion for holding wiring connected to the piezoelectric element and the metal plate, and a pressing member for pressing the wiring holding portion holding the wiring, wherein the periphery of the wiring is covered by the packing material forming the wiring holding portion, or by the packing material forming the wiring holding portion and the pressing member. A wiring structure characterized by the above.

2. The wiring holding portion has a wiring holding groove that covers the periphery of the wiring with the packing material by being pressed by the pressing member in a state where the wiring is inserted. The wiring structure according to claim 1, characterized by the above.

3. The groove width of the wiring holding groove is a length equal to or greater than the diameter of the wiring. The wiring structure according to claim 2, characterized by the above.

4. The groove width of the wiring holding groove is a length shorter than the diameter of the wiring. The wiring structure according to claim 2, characterized by the above.

5. The pressing member has a wiring recess into which the wiring is fitted, and the wiring holding portion deforms so as to sink a portion of the wiring that is not fitted into the wiring recess. The wiring structure according to claim 1, characterized by the above.

6. The wiring holding portion has a wiring holding groove into which the wiring is inserted, the housing has a fitting recess into which the wiring holding portion is fitted, and the wiring holding groove covers the periphery of the wiring with the packing material when the wiring holding portion is fitted into the fitting recess. The wiring structure according to claim 1, characterized by the above.

7. A metal plate to which a piezoelectric element is attached, and a packing provided in a housing and having a wiring holding portion for holding wiring connected to the piezoelectric element and the metal plate, wherein the wiring holding portion has a slit that covers the periphery of the wiring with the packing material forming the wiring holding portion when the wiring is pushed inside. A wiring structure characterized by the above.

8. Comprising the wiring structure according to any one of claims 1 to 7. An ultrasonic flowmeter characterized by the above.

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