JP2024068576A - Vibration sensor and vibration detection system - Google Patents

Abstract

To provide a vibration sensor and a vibration detection system that can ensure the accuracy of detecting vibration in a predetermined direction.SOLUTION: A vibration sensor 26 comprises a detection plate part 38, and a detection plate support part 40 supporting the detection plate part 38. Vibration of main girders 14 is transmitted to the detection plate part 38 through the detection plate support part 40, and deformation of the detection plate part 38 is detected by a piezoelectric material 32.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vibration sensor and a vibration detection system.

The following Patent Document 1 describes an invention related to a vibration sensor. This vibration sensor includes a thin-film piezoelectric body, an upper electrode provided on the upper surface of the piezoelectric body, a lower electrode provided on the lower surface of the piezoelectric body, and a weight provided on the upper surface of the upper electrode. In the prior art described in the following Patent Document 1, when vertical vibrations are input from an object to be detected to the vibration sensor, the vibrations cause the weight to vibrate in the vertical direction, generating a voltage in the piezoelectric body, and the vibrations generated in the object to be detected can be detected by detecting this voltage.

JP 2015-14530 A

However, in the prior art described in Patent Document 1, the weight vibrates not only in the vertical direction but also in a direction perpendicular to the vertical direction, so vibrations in a direction perpendicular to the vertical direction are also detected. In other words, the prior art described in Patent Document 1 has room for improvement in terms of ensuring the detection accuracy of vibrations in a specified direction.

The present invention takes into consideration the above-mentioned facts and aims to provide a vibration sensor and a vibration detection system that can ensure the detection accuracy of vibrations in a specified direction.

The vibration sensor according to the first aspect has a sheet-like piezoelectric body, a first electrode portion provided on a first surface on one side in the thickness direction of the piezoelectric body, a second electrode portion provided on a second surface on the other side in the thickness direction of the piezoelectric body, a plate-like detection plate portion provided on the surface of the second electrode portion opposite the piezoelectric body and having an outer periphery larger than the outer periphery of the piezoelectric body, and a detection plate support portion provided on the surface of the detection plate portion opposite the piezoelectric body and having an outer periphery smaller than the outer periphery of the piezoelectric body.

According to the vibration sensor of the first aspect, a first electrode portion is provided on a first surface of a sheet-like piezoelectric body on one side in the thickness direction of the piezoelectric body, and a second electrode portion is provided on a second surface on the other side in the thickness direction. When a force is applied to the piezoelectric body in its thickness direction, a charge signal corresponding to the magnitude of the force is output from the piezoelectric body via the first electrode portion and the second electrode portion. Therefore, by arranging the piezoelectric body so that vibrations of an object to be detected are transmitted, a charge signal corresponding to the magnitude of the vibration is output from the piezoelectric body, and the vibration can be detected.

From the viewpoint of ensuring the accuracy of detecting vibrations in a specific direction, it is preferable that when the vibration detection object vibrates in a specific direction, a force is applied to the piezoelectric body, and when the vibration detection object vibrates in a direction perpendicular to the specific direction, the application of force to the piezoelectric body can be suppressed.

In this embodiment, the device is equipped with a detection plate and a detection plate support that supports the detection plate, and the vibration of the object to be detected is transmitted to the detection plate via the detection plate support, and the deformation of the detection plate is detected by the piezoelectric body.

In more detail, in this embodiment, the detection plate portion is a plate whose outer periphery is larger than the outer periphery of the piezoelectric body, and is provided on the surface of the second electrode portion opposite the piezoelectric body.

On the other hand, the detection plate support part is provided on the surface of the detection plate part opposite the piezoelectric body, and its outer periphery is smaller than the outer periphery of the piezoelectric body. Therefore, in this embodiment, the outer periphery of the detection plate support part is located inside the outer periphery of the piezoelectric body when viewed in the thickness direction of the piezoelectric body.

In the above configuration, the detection plate support part is disposed on the side of the object to be detected, and when vibration is transmitted from the object to be detected to the detection plate part via the detection plate support part, if the direction of the vibration is the thickness direction of the piezoelectric body, the part of the detection plate part on the outer periphery side of the detection plate support part when viewed from the thickness direction will vibrate and deform in the thickness direction.

At this time, the piezoelectric body also deforms in accordance with the deformation of the detection plate, but since the volume of the piezoelectric body is constant, the piezoelectric body is polarized by expanding or contracting in its thickness direction, and a charge signal is output from the piezoelectric body.

On the other hand, when the direction of vibration transmitted from the vibration detection object to the detection plate via the detection plate support is perpendicular to the thickness direction of the piezoelectric body, the detection plate is displaced in the direction of the vibration, but deformation of the detection plate in the thickness direction due to the vibration is suppressed. Therefore, when the direction of vibration transmitted from the vibration detection object to the detection plate is perpendicular to the thickness direction of the piezoelectric body, the output of the charge signal from the piezoelectric body is suppressed.

In other words, in this embodiment, it is possible to increase the accuracy of detecting vibrations when the vibration direction of the vibration detection object is the thickness direction of the piezoelectric body, and to suppress detection of the vibrations when the vibration direction is perpendicular to the thickness direction.

The vibration sensor according to the second aspect is the vibration sensor according to the first aspect, in which the outer periphery of the piezoelectric body, the outer periphery of the detection plate portion, and the outer periphery of the detection plate support portion are each circular.

According to the vibration sensor of the second aspect, the piezoelectric body, the detection plate portion, and the detection plate support portion each have a circular outer periphery, which makes it possible to suppress localized deformation of these portions due to vibration of the vibration detection object. This increases the accuracy with which the piezoelectric body detects vibration in the thickness direction of the piezoelectric body in the vibration detection object.

The vibration sensor according to the third aspect is the vibration sensor according to the second aspect, in which a circular through-hole is formed in each of the central portions of the piezoelectric body, the first electrode portion, and the second electrode portion when viewed from the thickness direction.

As described above, the vibration sensor according to the third aspect detects the vibration of the object to be detected by using the piezoelectric body to detect the deformation of the outer peripheral portion of the detection plate support part of the detection plate part when viewed in the thickness direction of the piezoelectric body.

In other words, if the piezoelectric body is disk-shaped, the outer peripheral portion will contribute to detecting the deformation of the detection plate, but the center portion will not contribute to detecting the deformation. In other words, the center portion of the piezoelectric body does not follow the deformation of the detection plate, and therefore the deformation of the outer peripheral portion of the piezoelectric body is likely to be hindered by the center portion.

In this embodiment, a circular through-hole is formed in each of the central portions of the piezoelectric body, the first electrode portion, and the second electrode portion when viewed in the thickness direction of the piezoelectric body, so that the deformation of the outer periphery of the piezoelectric body can be prevented from being hindered.

The vibration sensor according to the fourth aspect is the vibration sensor according to the third aspect, further comprising a case portion including a metal lid portion arranged on one side of the first electrode portion in the thickness direction, and a bottom portion arranged on the other side of the detection plate support portion in the thickness direction and in close contact with the detection plate support portion, and a metal case main body portion in which the piezoelectric body, the first electrode portion, the second electrode portion, the detection plate portion, and the detection plate support portion are stored, and the center of the lid portion and the center of the detection plate portion are connected by a support portion inserted into the through portion, and a first conducting wire extending from the first electrode portion and a second conducting wire extending from the second electrode portion are arranged along the lid portion and the support portion.

The vibration sensor according to the fourth aspect includes a case portion including a metal lid portion and a metal case body portion. The lid portion is disposed on one side of the piezoelectric body in the first electrode portion in the thickness direction, and the case body portion stores the piezoelectric body, the first electrode portion, the second electrode portion, the detection plate portion, and the detection plate support portion. The bottom of the case body portion is disposed on the other side of the piezoelectric body in the thickness direction of the detection plate support portion, and is in close contact with the detection plate support portion.

Therefore, in this embodiment, the case protects the first electrode portion and the second electrode portion, etc. from electromagnetic waves emitted from the outside, and can suppress the inclusion of noise in the charge signal output from the piezoelectric body.

In addition, in this embodiment, the center of the lid and the center of the detection plate are connected by a support that is inserted through the through-holes of the piezoelectric body, the first electrode, and the second electrode, so that the lid is reinforced by the support. This makes it possible to suppress vibration of the lid due to vibrations from the object to be detected.

Furthermore, in this embodiment, the first conducting wire extending from the first electrode portion and the second conducting wire extending from the second electrode portion are arranged along the lid portion and the support portion. This prevents the first conducting wire and the second conducting wire from vibrating due to vibrations from the vibration detection object side, and thus prevents noise caused by vibrations from the vibration detection object side from being included in the charge signal output from the piezoelectric body.

The vibration detection system according to the fifth aspect includes a vibration sensor according to any one of the first to fourth aspects, and a signal conversion device that is disposed adjacent to the vibration sensor, is electrically connected to the piezoelectric body via the first electrode portion and the second electrode portion, and is capable of outputting a voltage signal proportional to the charge signal output from the piezoelectric body.

The vibration detection system according to the fifth aspect includes a signal conversion device that is electrically connected to the piezoelectric body via a first electrode portion and a second electrode portion. The signal conversion device outputs a voltage signal that is proportional to the charge signal output from the piezoelectric body.

However, if the piezoelectric body and the signal conversion device are separated from each other, the conductor wire used to electrically connect the first electrode section and the second electrode section to the signal conversion device becomes long, and it is conceivable that noise will be included in the charge signal output from the piezoelectric body due to the expansion and contraction of the conductor wire, etc.

In this embodiment, the vibration sensor and the signal conversion device are arranged adjacent to each other, so that the length of the conductor required to connect the first electrode section and the second electrode section to the signal conversion device can be shortened, and thus noise in the charge signal output from the piezoelectric body due to expansion and contraction of the conductor can be suppressed.

As described above, the vibration sensor and vibration detection system of the present invention have the excellent effect of ensuring the detection accuracy of vibrations in a specified direction.

1 is a cross-sectional view (a cross-sectional view showing a state cut along line 1-1 in FIG. 2) that illustrates a schematic configuration of a vibration sensor according to the present embodiment. 2 is a cross-sectional view (a cross-sectional view showing a state cut along line 2-2 in FIG. 1) that shows a schematic configuration of the vibration sensor according to the present embodiment. 1 is an exploded perspective view showing a schematic configuration of a main part of a vibration sensor according to an embodiment of the present invention; 2 is a side view showing a schematic configuration of a vibration detection unit constituting a part of the vibration detection system according to the present embodiment. FIG. 1 is a schematic diagram showing a state in which a vibration detection system according to an embodiment of the present invention is installed on a bridge.

Below, an example of an embodiment of a vibration sensor and vibration detection system according to the present invention will be described with reference to Figures 1 to 5.

As shown in FIG. 5, the "vibration detection system 10" according to this embodiment includes a plurality of vibration detection units 16 arranged along the longitudinal direction of the main girder 14 on the underside of the main girder 14 of the bridge 12, which is the object of vibration detection, a plurality of information accumulation units 18, a communication unit 20, an external server 22, and a monitoring computer 24.

As shown in FIG. 4, the vibration detection unit 16 includes a vibration sensor 26, a charge amplifier 28 as a signal conversion device, and a metal base plate 30 that fixes these to the main girder 14.

As shown in Figures 1 to 3, the vibration sensor 26 includes a piezoelectric body 32, a first electrode portion 34, a second electrode portion 36, a detection plate portion 38, a detection plate support portion 40, and a shield case 42 that contains these.

When viewed from above, the piezoelectric body 32 is in the form of a sheet with a circular outer periphery and a circular "through hole 44" formed in the center. When a force is applied to the piezoelectric body 32 in its thickness direction, it becomes polarized in the thickness direction, and an electric charge is generated on the surface in the thickness direction according to the magnitude of the force.

As an example, the piezoelectric body 32 is made of a thin-film piezoelectric film sheet containing PVDF (Polyvinylidene Fluoride). The piezoelectric body 32 may also be made of piezoelectric ceramics. In the following, unless otherwise specified, the thickness direction of the piezoelectric body 32 will be simply referred to as the thickness direction.

The first electrode portion 34 is provided on the "first surface 32A" on one side of the thickness direction of the piezoelectric body 32, and is a conductive film electrically connected to the piezoelectric body 32, and is made of silver or an alloy containing silver, for example. The first electrode portion 34 may be made of a metal such as platinum or carbon fiber. The first electrode portion 34 is circular with an outer periphery smaller than the outer periphery of the piezoelectric body 32 when viewed in the thickness direction, and a circular "through portion 46" with a diameter larger than the through portion 44 when viewed in the thickness direction is formed in the center. In addition, a "first conductor 56" electrically connected to the first electrode portion 34 extends from the first electrode portion 34 toward the through portion 46.

On the other hand, the second electrode portion 36 is provided on the "second surface 32B" on the other side in the thickness direction of the piezoelectric body 32 and has a configuration similar to that of the first electrode portion 34. Also, in the center of the second electrode portion 36, a circular "through portion 48" is formed whose diameter is larger than that of the through portion 44 when viewed in the thickness direction, similar to the first electrode portion 34. Also, from the second electrode portion 36, a "second conducting wire 58" electrically connected to the second electrode portion 36 extends toward the through portion 48.

The detection plate 38 is disposed along the other surface of the second electrode 36 in the thickness direction, i.e., the surface opposite the piezoelectric body 32, and is a circular plate whose outer periphery is larger than the outer periphery of the piezoelectric body 32 when viewed in the thickness direction. The detection plate 38 is bonded to the other surface of the second electrode 36 in the thickness direction with a bonding part (not shown) such as an adhesive, while being in close contact with the surface.

The detection plate support part 40 is disposed on the other side of the detection plate part 38 in the thickness direction, i.e., on the opposite side of the piezoelectric body 32, and is a circular plate or column whose outer periphery is smaller than the outer periphery of the piezoelectric body 32 when viewed in the thickness direction. The detection plate support part 40 is bonded to the surface of the other side of the thickness direction of the detection plate part 38 in a state of intimate contact with the surface with a bonding part (not shown) such as an adhesive.

The detection plate portion 38 and the detection plate support portion 40 are arranged so that their centers coincide with the center of the through-hole portion 44 when viewed from the thickness direction. In this embodiment, the detection plate portion 38 and the detection plate support portion 40 are made of aluminum or an alloy containing aluminum, for example, but they may also be made of a metal that is easy to cut, such as magnesium.

The shield case 42 has a "lid portion 50" and a "case body portion 52" each made of a metal capable of blocking electromagnetic waves, such as an aluminum alloy, and has a rectangular parallelepiped outer shape.

In more detail, the lid 50 is a square plate when viewed in the thickness direction, and a cylindrical "support 54" is provided at the center of the surface on the other side in the thickness direction, extending from that surface to the other side in the thickness direction. The support 54 is inserted through the penetrations 44, 46, and 48, and its tip is joined to the center of the surface on one side in the thickness direction of the detection plate 38 by a joint such as an adhesive (not shown). The support 54 may be separate from the lid 50.

The first conducting wire 56 and the second conducting wire 58 are arranged along the surface of the other thickness direction of the lid 50 and the support 54, and are joined by a joint (not shown) such as an adhesive.

The case body 52, on the other hand, is composed of a "bottom 52A" that is a square plate-like portion when viewed in the thickness direction, and an outer peripheral portion 52B that extends from the periphery of the bottom 52A to one side in the thickness direction. The case body 52 houses the piezoelectric body 32, the first electrode portion 34, the second electrode portion 36, the detection plate portion 38, and the detection plate support portion 40.

The surface of the bottom 52A on one side in the thickness direction is joined to the surface of the bottom 52A on the other side in the thickness direction by a joint such as an adhesive, not shown, while being in intimate contact with the surface of the bottom 52A on the other side in the thickness direction. On the other hand, the base plate 30 is in contact with the surface of the bottom 52A on the other side in the thickness direction, and the case main body 52 is attached to the base plate 30 by an attachment member, not shown. In other words, the vibration sensor 26 is positioned so that the detection plate support 40 is located on the main girder 14 side.

On the other hand, the periphery of the outer periphery 52B on one side in the thickness direction is joined to the lid 50 by a joint such as an adhesive (not shown). A recess 60 is formed by partially recessing the periphery of the outer periphery 52B on one side in the thickness direction toward the other side in the thickness direction, and the first conducting wire 56 and the second conducting wire 58 extend from the recess 60 to the outside of the shield case 42.

Returning to FIG. 4, the charge amplifier 28 is disposed adjacent to the vibration sensor 26 and includes an aluminum alloy case 62 that forms its outer shell, and a signal conversion unit (not shown) stored in the case 62. The signal conversion unit of the charge amplifier 28 is electrically connected to the piezoelectric body 32 via the first electrode unit 34, the second electrode unit 36, the first conductor 56, and the second conductor 58, and outputs a voltage signal proportional to the charge signal output from the piezoelectric body 32. The voltage signal output from the signal conversion unit is input to the information accumulation unit 18 via a signal line 64, as also shown in FIG. 5.

The information accumulation unit 18 is equipped with an analog-digital converter (not shown) and converts the voltage signals input from the multiple vibration detection units 16, i.e., the detection results from the vibration sensors 26, from analog signals to digital signals, and is capable of temporarily storing the detection results. The information accumulation unit 18 is then configured to transmit the detection results from the vibration sensors 26 to the communication unit 20, and the detection results are transmitted from the communication unit 20 via the network N to the external server 22 and are stored in the external server 22.

The external server 22 is also capable of communicating with the monitoring computer 24 via the network N. If an abnormal value is detected from the detection results by the vibration sensor 26 stored in the external server 22, the monitoring computer 24 displays a warning on the monitor 66 of the monitoring computer 24.

(Actions and Effects of the Present Embodiment)
Next, the operation and effects of this embodiment will be described.

In this embodiment, as shown in FIG. 1, a first electrode portion 34 is provided on a first surface 32A on one side in the thickness direction of a sheet-like piezoelectric body 32, and a second electrode portion 36 is provided on a second surface 32B on the other side in the thickness direction. When a force in the thickness direction is applied to the piezoelectric body 32, a charge signal corresponding to the magnitude of the force is output from the piezoelectric body 32 via the first electrode portion 34 and the second electrode portion 36. Therefore, by positioning the piezoelectric body 32 so that vibrations of the main beams 14 of the bridge 12 are transmitted, a charge signal corresponding to the magnitude of the vibrations is output from the piezoelectric body 32, and the vibrations can be detected.

From the viewpoint of ensuring the detection accuracy of vibrations in a specified direction, it is preferable that when the main girder 14 vibrates in a specified direction, for example the vertical direction, a force is applied to the piezoelectric body 32, and when the main girder 14 vibrates in the horizontal direction, the application of force to the piezoelectric body 32 can be suppressed.

In this embodiment, a detection plate portion 38 and a detection plate support portion 40 that supports the detection plate portion 38 are provided, and the vibration of the main girder 14 is transmitted to the detection plate portion 38 via the detection plate support portion 40, and the deformation of the detection plate portion 38 is detected by the piezoelectric body 32.

More specifically, in this embodiment, as shown in FIG. 2, the detection plate portion 38 is a plate whose outer periphery is larger than the outer periphery of the piezoelectric body 32, and is provided on the surface of the second electrode portion 36 opposite the piezoelectric body 32.

On the other hand, the detection plate support part 40 is provided on the surface of the detection plate part 38 opposite the piezoelectric body 32, and its outer periphery is smaller than the outer periphery of the piezoelectric body 32. Therefore, in this embodiment, the outer periphery of the detection plate support part 40 is located inside the outer periphery of the piezoelectric body 32 when viewed in the thickness direction of the piezoelectric body 32.

In the above configuration, when the detection plate support part 40 is disposed on the main girder 14 side and vibration is transmitted from the main girder 14 to the detection plate part 38 via the detection plate support part 40, if the direction of the vibration is vertical, i.e., the thickness direction, the outer peripheral part of the detection plate support part 40 when viewed from the thickness direction of the detection plate part 38 will vibrate in the thickness direction and deform.

At this time, the piezoelectric body 32 also deforms in accordance with the deformation of the detection plate portion 38, but since the volume of the piezoelectric body 32 is constant, the piezoelectric body 32 is polarized by expanding or contracting in the thickness direction, and a charge signal is output from the piezoelectric body 32.

On the other hand, when the direction of vibration transmitted from the main girder 14 to the detection plate section 38 via the detection plate support section 40 is horizontal, the detection plate section 38 is displaced along the direction of the vibration, but vertical deformation of the detection plate section 38 due to the vibration is suppressed. Therefore, when the direction of vibration transmitted from the main girder 14 to the detection plate section 38 is horizontal, i.e., perpendicular to the thickness direction, the output of the charge signal from the piezoelectric body 32 is suppressed.

In other words, in this embodiment, it is possible to increase the accuracy of detecting vibrations of the main girder 14 when the direction of the vibration is in the thickness direction, and to suppress detection of the vibrations when the direction of the vibration is perpendicular to the thickness direction.

In addition, in this embodiment, the outer periphery of the piezoelectric body 32, the detection plate portion 38, and the detection plate support portion 40 are each circular, which can prevent localized deformation of these portions due to vibration of the main girder 14. This can increase the accuracy with which the piezoelectric body 32 detects vertical vibrations in the main girder 14.

In addition, in this embodiment, as described above, the piezoelectric element 32 detects the deformation of the outer peripheral portion of the detection plate support portion 40 in the detection plate portion 38 when viewed from the thickness direction, thereby detecting the vibration of the main girder 14.

In other words, if the piezoelectric body 32 is disk-shaped, the outer peripheral portion will contribute to detecting the deformation of the detection plate portion 38, but the center portion will not contribute to detecting the deformation. In other words, since the center portion of the piezoelectric body 32 does not follow the deformation of the detection plate portion 38, it is conceivable that the deformation of the outer peripheral portion of the piezoelectric body 32 is hindered by the center portion.

In this embodiment, a circular through-hole is formed in the center of each of the piezoelectric body 32, the first electrode portion 34, and the second electrode portion 36 when viewed from the thickness direction, so that the deformation of the outer periphery of the piezoelectric body 32 can be prevented from being hindered.

In this embodiment, the shield case 42 includes a metallic lid portion 50 and a metallic case body portion 52. The lid portion 50 is disposed on one side of the first electrode portion 34 in the thickness direction, and the case body portion 52 houses the piezoelectric body 32, the first electrode portion 34, the second electrode portion 36, the detection plate portion 38, and the detection plate support portion 40. The bottom portion 52A of the case body portion 52 is disposed on the other side of the detection plate support portion 40 in the thickness direction and is in close contact with the detection plate support portion 40.

For this reason, in this embodiment, the shield case 42 protects the first electrode portion 34, the second electrode portion 36, etc. from electromagnetic waves emitted from the outside, and can suppress the inclusion of noise in the charge signal output from the piezoelectric body 32.

In addition, in this embodiment, the center of the lid portion 50 and the center of the detection plate portion 38 are connected by a support portion 54 inserted through the through-hole portion 44 of the piezoelectric body 32, the through-hole portion 46 of the first electrode portion 34, and the through-hole portion 48 of the second electrode portion 36, so that the lid portion 50 is reinforced by the support portion 54. Therefore, it is possible to suppress vibration of the lid portion 50 due to vibration from the main girder 14 side.

Furthermore, in this embodiment, the first conducting wire 56 extending from the first electrode portion 34 and the second conducting wire 58 extending from the second electrode portion 36 are arranged along the cover portion 50 and the support portion 54. This prevents the first conducting wire 56 and the second conducting wire 58 from vibrating due to vibrations from the main beam 14 side, and thus prevents noise caused by vibrations from the main beam 14 side from being included in the charge signal output from the piezoelectric body 32.

In addition, this embodiment includes a charge amplifier 28, which is electrically connected to the piezoelectric body 32 via a first electrode portion 34 and a second electrode portion 36. The charge amplifier 28 outputs a voltage signal proportional to the charge signal output from the piezoelectric body 32.

However, if the piezoelectric body 32 and the charge amplifier 28 are separated from each other, the first conductor 56 and the second conductor 58 used to electrically connect the first electrode section 34 and the second electrode section 36 to the charge amplifier 28 become longer, and it is conceivable that noise may be included in the charge signal output from the piezoelectric body 32 due to the expansion and contraction of these wires.

In this embodiment, the vibration sensor 26 and the charge amplifier 28 are arranged adjacent to each other, so that the lengths of the first and second conductors 56 and 58 required to connect the first and second electrode sections 34 and 36 to the charge amplifier 28 can be shortened, and thus noise in the charge signal output from the piezoelectric body 32 due to expansion and contraction of these conductors can be suppressed.

In this way, the vibration sensor 26 and vibration detection system 10 according to this embodiment can ensure the detection accuracy of vibrations in a specified direction.

<Supplementary explanation of the above embodiment>
(1) In the above embodiment, the vibration sensor 26 and the vibration detection system 10 are used to detect vertical vibrations of the bridge 12, but the object of vibration detection by the vibration sensor 26 and the vibration detection system 10 may be a building or the like. In addition, by appropriately changing the installation direction of the vibration sensor 26, it is possible to detect vibrations in any direction.

(2) In the above embodiment, the piezoelectric body 32, the first electrode portion 34, and the second electrode portion 36 have through-holes formed therein. However, depending on the frequency of the vibration to be detected and the specifications of the vibration sensor 26, these may not have through-holes. In this case, the first conducting wire 56 and the second conducting wire 58 may be disposed along the inner surface of the case body portion 52.

(3) Furthermore, in the above-described embodiment, the detection plate portion 38 and the detection plate support portion 40 are configured as separate bodies, but they may be integrated depending on the frequency of the vibration to be detected and the specifications of the vibration sensor 26. Also, depending on the frequency of the vibration to be detected, the shape and material of the detection plate portion 38 and the detection plate support portion 40 may be changed, and the shape and material of the piezoelectric body 32, the first electrode portion 34, and the second electrode portion 36 may be changed. For example, the piezoelectric body 32, the first electrode portion 34, the second electrode portion 36, the detection plate portion 38, and the detection plate support portion 40 may be polygonal when viewed in the thickness direction.

10 vibration detection system 26 vibration sensor 28 charge amplifier (signal conversion device)
32 Piezoelectric body 32A First surface 32B Second surface 34 First electrode portion 36 Second electrode portion 38 Detection plate portion 40 Detection plate support portion 42 Shield case (case portion)
44 Penetrating portion 46 Penetrating portion 48 Penetrating portion 50 Lid portion 52 Case body portion 52A Bottom portion 54 Support portion 56 First conducting wire 58 Second conducting wire

Claims (5)

A sheet-shaped piezoelectric body;
A first electrode portion provided on a first surface of the piezoelectric body on one side in a thickness direction;
a second electrode portion provided on a second surface of the piezoelectric body on the other side in the thickness direction;
a detection plate portion provided on a surface of the second electrode portion opposite to the piezoelectric body and having an outer periphery larger than an outer periphery of the piezoelectric body;
a detection plate support portion provided on a surface of the detection plate portion opposite to the piezoelectric body, the detection plate support portion having an outer periphery smaller than an outer periphery of the piezoelectric body;
A vibration sensor having a The outer periphery of the piezoelectric body, the outer periphery of the detection plate portion, and the outer periphery of the detection plate support portion are each circular.
The vibration sensor according to claim 1 . a through-hole having a circular shape as viewed from the thickness direction is formed in each of the central portions of the piezoelectric body, the first electrode portion, and the second electrode portion;
The vibration sensor according to claim 2 . a metal cover portion disposed on one side of the first electrode portion in the thickness direction;
a metal case main body portion that is disposed on the other side of the detection plate support portion in the thickness direction and includes a bottom portion in close contact with the detection plate support portion, and that houses the piezoelectric body, the first electrode portion, the second electrode portion, the detection plate portion, and the detection plate support portion;
A case part including:
A center portion of the cover portion and a center portion of the detection plate portion are connected by a support portion inserted through the through-hole,
a first conductive wire extending from the first electrode portion and a second conductive wire extending from the second electrode portion are arranged along the lid portion and the support portion;
The vibration sensor according to claim 3 . A vibration sensor according to any one of claims 1 to 4;
a signal conversion device disposed adjacent to the vibration sensor, electrically connected to the piezoelectric body via the first electrode portion and the second electrode portion, and capable of outputting a voltage signal proportional to a charge signal output from the piezoelectric body;
Equipped with
Vibration detection system.