JP2020139751A - Vibration sensor and resonant frequency adjustment system - Google Patents

Abstract

To provide a vibration sensor which allows for adjusting resonant frequency of unwanted resonance, and to provide a resonant frequency adjustment system.SOLUTION: A vibration sensor is provided, comprising: a leg 24 made of a permanent magnet to be attached to a vibrating body 1 by magnetic force and fixed to a bottom face 20B of a case body 20; a vibration measurement unit mounted on a substrate 16 housed in the case body 20 and configured to measure vibration generated by the vibrating body 1; and a computation unit configured to compute a variation in thickness of the leg, when unwanted resonance caused by the leg 24 is measured by the vibration measurement unit, from a thickness D of the leg 24 with the unwanted resonance and a variation in resonant frequency of the unwanted resonance.SELECTED DRAWING: Figure 4

Description

The present invention relates to a vibration sensor and a resonance frequency adjustment system that are attached to a vibrating body and measure the vibration of the vibrating body.

Generally, a vibration sensor that is attached to a vibrating body such as a motor or an engine to measure the vibration of the vibrating body is known. This type of vibration sensor measures, for example, the vibration frequency generated during the operation of the vibrating body, and determines whether or not the operation of the vibrating body is normal based on the measured vibration frequency. Conventionally, a housing having a vibration detecting element for detecting vibration and a circuit board on which the vibration detecting element is mounted, and a permanent magnet fixed to the housing are provided, and the vibrating body (detected body) is formed by the magnetic force of the permanent magnet. An attached vibration detection sensor has been proposed (see, for example, Patent Document 1).

JP-A-2017-116268

By the way, in the configuration in which the vibration sensor is attached to the vibrating body by the magnetic force of the permanent magnet, a moment due to the thickness of the permanent magnet acts on the center of gravity of the vibrating sensor, so that the vibrating body vibrates at a specific frequency due to the vibration of the permanent magnet. Unwanted resonance other than the above may occur. When unnecessary resonance occurs, there is a problem that it is not possible to determine whether the vibration measured by the vibration sensor is due to a change in waveform due to an abnormality of the vibrating body or due to resonance.

The present invention has been made in view of the above, and an object of the present invention is to provide a vibration sensor and a resonance frequency adjustment system capable of adjusting the resonance frequency of unnecessary resonance.

In order to solve the above-mentioned problems and achieve the object, the vibration sensor according to the present invention is mounted on a permanent magnet fixed to the bottom surface of the housing and attracted to the vibrating body by magnetic force, and a substrate housed in the housing. When the vibration measuring unit that measures the vibration generated by the vibrating body and the vibration measuring unit measure the unnecessary resonance caused by the permanent magnet, the thickness of the permanent magnet in which the unnecessary resonance occurs and the amount of change in the thickness of the permanent magnet or It is characterized by including a calculation unit for calculating the thickness change amount or the other shift amount based on one of the shift amounts of the resonance frequency of the unnecessary resonance.

In this configuration, the calculation unit sets the shift amount of the resonance frequency to F [Hz], the thickness D [m] of the permanent magnet, the thickness change amount D'[m] of the permanent magnet, the gravitational acceleration g [m / S], and the permanent magnet. When the coefficient α is based on the characteristics of the magnet, the thickness change amount or the shift amount may be calculated based on the mathematical formula (1).

Further, the resonance frequency adjustment system according to the present invention measures a permanent magnet fixed to the bottom surface of the housing and attracted to the vibrating body by magnetic force, and mounted on a substrate housed in the housing to measure the vibration generated by the vibrating body. When a vibration sensor equipped with a vibration measuring unit and the vibration measuring unit measure unnecessary resonance caused by the permanent magnet, the thickness of the permanent magnet in which the unnecessary resonance occurs, the amount of change in the thickness of the permanent magnet, or the unnecessary resonance It is characterized by including a calculation unit having a calculation unit for calculating the thickness change amount or the other of the shift amount based on one of the shift amounts of the resonance frequency.

According to the present invention, the resonance frequency of unnecessary resonance can be easily adjusted.

FIG. 1 is a schematic configuration diagram of a vibration detection system including a vibration sensor according to the first embodiment. FIG. 2 is a functional block diagram of the vibration sensor. FIG. 3 is an exploded perspective view showing the internal configuration of the vibration sensor. FIG. 4 is a side sectional view showing the internal configuration of the vibration sensor. FIG. 5 is a graph showing the relationship between the intensity of vibration and the frequency when the vibration sensor is vibrated by using the leg portion having the first thickness. FIG. 6 is a graph showing the relationship between the intensity of vibration and the frequency when the vibration sensor is vibrated by using the leg portion having a second thickness thinner than the first thickness. FIG. 7 is a functional block diagram showing a resonance frequency adjustment system having a vibration sensor according to the second embodiment.

The embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a vibration detection system including a vibration sensor according to the first embodiment. FIG. 2 is a functional block diagram of the vibration sensor. The vibration detection system 100 monitors, for example, the vibration state of the vibrating body 1 such as a motor or an engine, and determines whether or not the operation of the vibrating body 1 is normal. As shown in FIG. 1, the vibration detection system 100 includes a plurality of vibration sensors 10 attached to the vibrating body 1, a receiving unit 2 that receives measurement data measured by each vibration sensor 10 via wireless communication or the like. It includes a remote monitoring device (server device) 3 that monitors the operating state of the vibrating body 1 from the received measurement data. The receiving unit 2 and the remote monitoring device 3 are installed at a location physically separated from the vibrating body 1. The receiving unit 2 transmits the received measurement data to the remote monitoring device 3. The means of transmission may be wireless communication or wired communication. The remote monitoring device 3 stores the received measurement data in a database, analyzes the measurement data, and determines whether or not the operation of the vibrating body 1 is normal based on the measurement data. Further, when the remote monitoring device 3 determines that the operation of the vibrating body 1 is abnormal, the remote monitoring device 3 notifies the user that the abnormality has occurred.

As shown in FIG. 2, the vibration sensor 10 includes a communication unit 11, a vibration measurement unit 12, a filter processing unit 13, a control unit 14, a calculation unit 19, and a battery (power supply unit) 15. The communication unit 11 has a function of wirelessly communicating with the reception unit 2 and includes an antenna. For wireless communication, for example, a wireless communication method such as Wi-Fi (registered trademark) can be used. In addition to this, a short-range wireless communication method such as infrared rays or Bluetooth (registered trademark) may be used. The communication between the vibration sensor 10 and the receiving unit 2 is not limited to wireless communication, and may be performed by wire or a combination of wireless and wired communication.

The vibration measuring unit 12 is a multi-axis (3 axes; X-axis, Y-axis, Z-axis) acceleration measuring unit, and measures the frequency at which vibration (acceleration) occurs in each axial direction and the magnitude of the vibration. The filter processing unit 13 removes a noise component included in the measurement data measured by the vibration measuring unit 12. The calculation unit 19 calculates the shift amount of the resonance frequency of the unnecessary resonance or the thickness change amount of the leg portion made of the permanent magnet when the unnecessary resonance described later occurs. The control unit 14 is, for example, a controller equipped with a processor such as a CPU (Central Processing Unit), and by executing a program stored in the memory, each component (communication unit 11, vibration measurement unit 12, filter processing). The operation of unit 13 and calculation unit 19) is controlled. The control unit 14 transmits the filtered measurement data to the reception unit 2 via the communication unit 11. In the present embodiment, the communication unit 11, the vibration measurement unit 12, the filter processing unit 13, the calculation unit 19, and the control unit 14 are mounted on the substrate 16.

The battery 15 is connected to the substrate 16 of the vibration sensor 10 to supply electric power to each component on the substrate 16. The battery 15 is a disk-shaped (coin-shaped) primary battery called, for example, a coin battery or a button battery. The battery 15 may be a primary battery having a shape other than a disk shape (coin type). Therefore, from the viewpoint of suppressing the power consumption of the battery 15, the vibration sensor 10 operates periodically once in a predetermined cycle (for example, one day) for a predetermined time (for example, one minute), and intermittently vibrates the vibrating body 1. And the measurement data is transmitted to the receiving unit 2. This cycle and operating time can be changed as appropriate. The vibration sensor 10 may be configured to continuously measure the vibration of the vibrating body 1 and transmit the measurement data to the receiving unit 2.

Next, the internal configuration of the vibration sensor 10 will be described. FIG. 3 is an exploded perspective view showing the internal configuration of the vibration sensor. FIG. 4 is a side sectional view showing the internal configuration of the vibration sensor. As shown in FIG. 3, the vibration sensor 10 includes a case body 20, a battery 15, a substrate 16 and a spacer 17 housed in the case body 20, and a lid 21. The case body 20 is formed in a substantially square bottomed box shape with rounded corners using a synthetic resin material such as plastic. Inside the case body 20, a wall portion 22 forming a circular space 20A in which the disk-shaped battery 15 is housed is provided. The wall portion 22 is formed lower than the case main body 20, and a fixing portion 22A to which a substantially square substrate 16 is fixed is formed on the upper surface of the wall portion 22.

Through holes 16A are formed at the four corners of the substrate 16, and screw holes 22B are formed at the corresponding portions of the fixing portion 22A. As a result, the substrate 16 is screwed to the fixing portion 22A by the screw 23. As shown in FIG. 3, the battery 15 is formed in a disk shape and includes a pair of positive electrode terminals (terminals) 15A bonded to the positive electrode and a negative electrode terminal (terminal) 15B bonded to the negative electrode. The positive electrode terminal 15A and the negative electrode terminal 15B are adhered to the battery by, for example, soldering, and extend in the axial direction of the battery 15 (upper in FIGS. 3 and 4). The positive electrode terminal 15A and the negative electrode terminal 15B are inserted into holes (for example, through holes) 16B formed in the substrate 16 and then fixed by soldering or the like. Therefore, the battery 15 is mounted on the substrate 16 by the positive electrode terminal 15A and the negative electrode terminal 15B.

As shown in FIGS. 3 and 4, the spacer 17 is inserted into the gap between the battery 15 and the substrate 16 to fill the gap. The spacer 17 is a foamed elastic member (for example, PORON (registered trademark) manufactured by Rogers INOAC Corporation) made of an insulating material (for example, urethane foam), and the spacer 17 is compressed in the thickness direction to form a battery 15. It is arranged in the gap between the substrate 16 and the substrate 16. In this configuration, the spacer 17 elastically deforms according to the fluctuation of the gap between the battery 15 and the substrate 16, so that the gap between the battery 15 and the substrate 16 can be reliably filled.

Further, as shown in FIG. 3, the spacer 17 is formed with notches 17A and 17B so as not to come into contact with the positive electrode terminal 15A and the negative electrode terminal 15B, respectively. The notches 17A and 17B are provided at positions avoiding the positive electrode terminal 15A and the negative electrode terminal 15B, and even if water adheres to the spacer 17, the positive electrode terminal 15A passed through the spacer 17 Prevents a short circuit between the negative electrode terminal 15B and the negative electrode terminal 15B. Further, the spacer 17 is adhered to a negative electrode (opposing surface) facing the substrate 16 of the battery 15. According to this, since the spacer 17 is compressed by pressing the battery 15 against the substrate 16, the positive electrode terminal 15A and the negative electrode terminal 15B can be soldered to the substrate 16 in this compressed state, and the battery 15 and the substrate 16 can be soldered. The spacer 17 can be easily sandwiched in the gap between the two.

The lid 21 is made of the same material as the case body 20 and closes the opening of the case body 20. In the present embodiment, the lid 21 and the case body 20 are watertightly fixed to each other by using, for example, heat welding or an adhesive to function as a housing.

The vibration sensor 10 includes legs 24 on the bottom surface 20B of the case body 20. The leg portion 24 is formed of a permanent magnet having two poles magnetized in the thickness direction. Therefore, it can be easily attached (adsorbed) to the installation surface 1A of the vibrating body 1 made of the magnetic material by the magnetic force of the leg portion 24 (permanent magnet). The leg portion 24 is formed, for example, in the shape of a disk having a thickness of D [m], and includes a male screw 25 that protrudes through the central portion as shown in FIG. On the other hand, a female screw 20C is formed on the bottom surface 20B of the case body 20 at a position corresponding to the male screw 25, and the leg portion 24 is screwed to the case body 20. Further, in the present embodiment, female threads are formed at the central portion and the four corners of the bottom surface 20B of the case main body 20, respectively, and as shown in FIG. 3, one leg portion 24 is formed at the central portion of the case main body 20. Alternatively, it is possible to select a configuration in which four legs 24 are attached to each of the four corners of the case body 20. It should be noted that at least a part of the magnets of the leg portion 24 may be composed of a magnet that does not meet the specifications of a permanent magnet or a magnet other than other permanent magnets such as a temporary magnet.

As described above, the vibration sensor 10 measures the vibration (frequency) generated when the vibrating body 1 is attached to the vibrating body 1 and the vibrating body 1 operates. On the other hand, in the configuration in which the vibration sensor 10 is attached to the installation surface 1A of the vibrating body 1 by the magnetic force of the leg portion 24 (permanent magnet) as in the present embodiment, the thickness of the leg portion 24 depends on the center of gravity of the vibration sensor 10. Since a moment acts, it is different from the vibration of the vibrating body 1 at a specific frequency due to the vibration of the leg 24 within a predetermined measurement range (for example, 0 to 2000 Hz) for measuring the vibration frequency of the vibrating body 1. Unwanted resonance may occur.

According to the diligent research of the inventors, there is a correlation between the thickness of the leg 24 and the resonance frequency of unnecessary resonance, and the thinner the leg 24, the lower the position of the center of gravity of the vibration sensor 10. , It was found that the resonance frequency shifts to the high frequency range. Therefore, in the present embodiment, by changing the thickness of the leg portion 24, the resonance frequency of the unnecessary resonance generated due to the vibration of the leg portion 24 can be adjusted. Next, the point that the resonance frequency moves with the change in the thickness of the leg portion 24 (permanent magnet) will be described. The leg portion 24 may have a shape of a triangular prism, a quadrangular prism, any other polygonal prism, a tubular body having an elliptical cross section, or any combination thereof, in addition to the disk shape. At least one of the plurality of legs 24 may have a shape different from that of the other legs 24. At least one of the plurality of legs 24 may have a size different from that of the other legs 24.

FIG. 5 is a graph showing the relationship between the intensity of vibration and the frequency when the vibration sensor is vibrated by using the leg portion having the first thickness. FIG. 6 is a graph showing the relationship between the intensity of vibration and the frequency when the vibration sensor is vibrated by using the leg portion having a second thickness thinner than the first thickness. In FIGS. 5 and 6, the first thickness of the leg portion 24 is D = 8.0 [mm], and the second thickness is D = 6.0 [mm]. Vibration to the vibration sensor was performed using a vibration test device. The vibration test device is a device that generates a forced vibration set to an arbitrary force, acceleration, or frequency, and performs a vibration evaluation test by a vibration load. As shown in FIG. 4, the direction in the vibration evaluation test is the stacking direction of the leg 24 and the case body 20, that is, the thickness direction of the leg 24 is the Z-axis direction, and the direction orthogonal to the Z-axis direction (for example, a pair). The direction in which the positive electrode terminals 15A of the above are arranged side by side) is defined as the X-axis direction, and the directions orthogonal to the X-axis direction and the Z-axis direction are defined as the Y-axis direction. The vibration sensor 10 is installed in the vibration evaluation test so that the Z-axis direction is the vertical direction.

The vibration conditions in this embodiment are
Gives single sinusoidal vibration in the vertical direction Frequency: Logarithmic sweep (4 oct / min)
Amplitude: 10 mm (0-p)
Acceleration: 2.0G
And said. The conditions for the vibration sensor were the same except for the thickness of the leg 24.

In FIGS. 5 and 6, reference numeral P indicates an input (amplitude) in the vertical direction. Further, reference numerals Q, R, and S indicate outputs (amplitudes) in the X-axis direction, the Y-axis direction, and the Z-axis direction (vertical direction), respectively. As shown in FIG. 5, in the configuration in which the leg portion 24 has the first thickness (D = 8.0 [mm]), the frequency is about 750 to 760 Hz (indicated by reference numeral F1) in the X-axis direction, the Y-axis direction, and Unwanted resonances Q1, R1, and S1 that are output in the Z-axis direction can be seen. These unnecessary resonances Q1, R1, and S1 are unnecessary resonances caused by the vibration of the leg portion 24 (permanent magnet).

On the other hand, in the configuration in which the leg portion 24 is thinned to a second thickness (D = 6.0 [mm]), the frequency is about 850 to 870 Hz (indicated by the reference numeral F2) in the X-axis direction, the Y-axis direction, and Z. Unwanted resonances Q2, R2, and S2 that are output in the axial direction can be seen. By reducing the thickness of the leg portion 24 from the first thickness to the second thickness in this way, the resonance frequencies of the unnecessary resonances Q2, R2, and S2 caused by the vibration of the leg portion 24 are unnecessary resonances Q1, R1, It moves (shifts) to a high frequency range by about 100 Hz with respect to the resonance frequency of S1. Further, the outputs (amplitudes) of these unnecessary resonances Q2, R2, and S2 are lower than the outputs (amplitudes) of the unnecessary resonances Q1, R1, and S1, respectively. Therefore, by changing the thickness of the leg portion 24 (permanent magnet), the resonance frequency of unnecessary resonance caused by the vibration of the leg portion 24 (permanent magnet) can be easily adjusted.

Next, a method of adjusting the resonance frequency will be described. First, the thickness D (first thickness) of the leg portion 24 of the vibration sensor 10 in the initial state is measured. Then, the vibration sensor 10 in the initial state is installed in, for example, a vibration evaluation test to measure the resonance frequency of unnecessary resonance caused by the vibration of the leg portion 24 having the first thickness. Data on the thickness (first thickness) of the leg portion 24 and the resonance frequency of unnecessary resonance may be input to the calculation unit 19 at any time when measured, or the data measured in advance may be stored in the control unit 14. It may be stored in a part (not shown).

Subsequently, with respect to the vibrating body 1 in which the vibrating sensor 10 is installed, the measurement range of the natural frequency when the vibrating body 1 operates is investigated. Since the measurement range differs for each vibrating body 1, it is necessary to compare the measurement range with the resonance frequency and adjust the resonance frequency when the resonance frequency is included in the measurement range. In this case, the amount of change F (shift amount) until the resonance frequency is out of the measurement range is obtained, and this amount of change F is input to the calculation unit 19. On the other hand, if the resonance frequency is not included in the measurement range in the initial state, the process ends without adjusting the resonance frequency.

Subsequently, the calculation unit 19 sets the amount of change in the resonance frequency to F [Hz], the thickness D [m] of the leg portion 24, the gravitational acceleration g [m / S], and the coefficient α based on the characteristics of the permanent magnet, and sets the formula ( Based on 1), the amount of change in thickness D'[m] of the leg portion 24 is calculated. The calculated thickness change amount D'can be displayed on the display unit (not shown) of the connected external device via, for example, the communication unit 11.

This formula 1 was conceived by the inventors from a formula based on the isochronism of the pendulum. By inputting the change amount F of the resonance frequency and the thickness D of the leg portion 24 into the mathematical formula 1, the thickness change amount D'of the leg portion 24 that changes the resonance frequency by the change amount F can be calculated. According to this, the resonance frequency of unnecessary resonance can be easily adjusted by changing the thickness of the leg portion 24 to the leg portion 24 having a new thickness (second thickness) in which the thickness change amount D'is changed. Can be done. Therefore, by adjusting the resonance frequency to the outside of the measurement range of the vibration sensor 10, it is possible to accurately determine whether or not the operation of the vibrating body 1 is normal. That is, in order to calculate the thickness change amount or the other of the shift amount based on the thickness of the permanent magnet in which the unnecessary resonance has occurred and one of the thickness change amount of the permanent magnet or the shift amount of the resonance frequency of the unnecessary resonance. By changing the thickness of the permanent magnet, the resonance frequency of unnecessary resonance can be easily adjusted. Therefore, by adjusting the resonance frequency to the outside of the measurement range of the vibration sensor, it is possible to accurately determine whether or not the operation of the vibrating body is normal.

In particular, the calculation unit 19 can easily calculate the thickness change amount D'of the leg portion 24 by using the above-mentioned formula 1.

Further, when the leg portion 24 whose thickness change amount D'is known is used, by inputting the thickness change amount D'and the thickness D of the leg portion 24 into the mathematical formula 1, the thickness change amount D'changes by the thickness change amount D'. The amount of change F in the resonance frequency of the legs 24 can be calculated. Therefore, for example, when the leg portion has an existing thickness, it can be easily determined whether or not the resonance frequency is included in the measurement range.

[Second Embodiment]
FIG. 7 is a functional block diagram showing a resonance frequency adjustment system having a vibration sensor according to the second embodiment. In the first embodiment, the vibration sensor 10 is provided by mounting the calculation unit 19 on the substrate 16, but the calculation unit 19 may be provided separately from the vibration sensor 10. The same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 7, the resonance frequency adjustment system 50 includes a vibration sensor 10A and a calculation unit 40. The vibration sensor 10A is different in that it does not include the calculation unit 19 described above, and has the same other configurations as the vibration sensor 10.

The calculation unit 40 includes a communication unit 41, the above-mentioned calculation unit 19, a control unit 42, and a display unit 43. The calculation unit 40 may be provided as a single unit, or may be integrally provided with an external device such as the remote monitoring device 3 described above.

The communication unit 41 has a function of wirelessly communicating with the communication unit 11 of the vibration sensor 10A, and includes an antenna. The wireless communication may be directly performed with the vibration sensor 10A, or may be performed via a repeater such as a receiving unit. Further, it may be configured so that it can communicate with the vibration sensor 10A by wire. Further, the calculation unit 40 can connect a plurality of vibration sensors 10A in a communicable manner. According to this, each thickness change amount D'in the plurality of vibration sensors 10A can be easily calculated. The control unit 42 is, for example, a controller equipped with a processor such as a CPU (Central Processing Unit), and by executing a program stored in the memory, each component (communication unit 41, calculation unit 19, display unit 43). ) Controls the operation. The display unit 43 is composed of a liquid crystal display device or the like that displays various information output screens, and displays the thickness change amount D'of the leg portion 24 or the resonance frequency change amount F calculated by the calculation unit 19. Further, a touch panel may be provided on the display unit 43 so that information such as the thickness D of the leg portion 24 can be input.

As described above, according to the present embodiment, when the vibration measuring unit 12 measures the unnecessary resonance caused by the leg portion 24 (permanent magnet), the thickness D of the leg portion 24 in which the unnecessary resonance occurs and the unnecessary resonance occur. Since the calculation unit 19 for calculating the thickness change amount D'of the leg portion 24 based on the change amount F of the resonance frequency of the above is provided, the resonance frequency of unnecessary resonance is generated by changing the thickness of the leg portion 24 (permanent magnet). Can be easily adjusted. Therefore, by adjusting the resonance frequency to the outside of the measurement range of the vibration sensors 10 and 10A, it is possible to accurately determine whether or not the operation of the vibrating body 1 is normal.

The present invention is not limited to the above embodiment. That is, it can be modified in various ways without departing from the gist of the present invention. For example, in the above embodiment, the change amount F of the resonance frequency of unnecessary resonance or the change amount F of the resonance frequency of unnecessary resonance is based on one of the thickness D of the leg portion 24 and the change amount F of the resonance frequency of unnecessary resonance or the thickness change amount D'of the leg portion 24. Although the configuration is provided with a calculation unit 19 for calculating the other of the thickness change amount D'of the leg portion 24, the change amount F of the resonance frequency of unnecessary resonance or the thickness change amount D'of the leg portion 24 is manually calculated. By changing the thickness of the leg portion 24 (permanent magnet), it is possible to construct an invention of a resonance frequency adjusting method for adjusting the resonance frequency of unnecessary resonance caused by the vibration of the leg portion 24 (permanent magnet).

The contents of the present disclosure may be modified and modified by those skilled in the art based on the present disclosure. Therefore, these modifications and modifications are within the scope of this disclosure. For example, in each embodiment, each functional unit, each means, each step, etc. are added to other embodiments so as not to be logically inconsistent, or each functional unit, each means, each step, etc. of other embodiments. Can be replaced with. Further, in each embodiment, it is possible to combine or divide a plurality of each functional unit, each means, each step, and the like into one. Further, each of the above-described embodiments of the present disclosure is not limited to faithful implementation of each of the embodiments described above, and each of the features may be combined or a part thereof may be omitted as appropriate. You can also do it.

1 Vibrator 2 Receiver 3 Remote monitoring device 10, 10A Vibration sensor 11 Communication unit 12 Vibration measurement unit 13 Filter processing unit 14 Control unit 15 Battery 19 Calculation unit 20 Case body (housing)
21 Lid (housing)
24 legs (permanent magnet)
40 Calculation unit 41 Communication unit 42 Control unit 43 Display unit 50 Resonance frequency adjustment system 100 Vibration detection system D Leg thickness D'Leg thickness change amount F Resonance frequency change amount (shift amount)
g Gravitational acceleration

Claims (3)

A magnet that is fixed to the bottom of the housing and attracts to the vibrating body by magnetic force,
A vibration measuring unit mounted on a substrate housed in the housing and measuring the vibration generated by the vibrating body,
When the vibration measuring unit measures the unwanted resonance caused by the magnet, the thickness of the magnet in which the unwanted resonance occurs and the thickness change amount of the magnet or the shift amount of the resonance frequency of the unwanted resonance Based on this, a vibration sensor including a calculation unit that calculates the thickness change amount or the other of the shift amount. The calculation unit
The shift amount of the resonance frequency is F [Hz],
The thickness D [m] of the magnet,
Amount of change in thickness of the magnet D'[m],
Gravitational acceleration g [m / S],
When the coefficient α is based on the characteristics of the magnet,
The vibration sensor according to claim 1, wherein the thickness change amount or the shift amount is calculated based on the mathematical formula (1).

A vibration sensor including a magnet fixed to the bottom surface of the housing and attracted to the vibrating body by magnetic force, and a vibration measuring unit mounted on a substrate housed in the housing and measuring the vibration generated by the vibrating body.
When the vibration measuring unit measures unnecessary resonance caused by the magnet, the thickness of the magnet in which the unnecessary resonance occurs and the thickness change amount of the magnet or the shift amount of the resonance frequency of the unnecessary resonance Based on this, a resonance frequency adjustment system including a calculation unit having a calculation unit for calculating the thickness change amount or the other of the shift amount.

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