JP2016166838A - Detector and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To amplify a vibration of a specific wavelength and detect the vibration.SOLUTION: The detector amplifies a vibration with a wavelength of λ propagating in an object 10 and detects the vibration. A first vibration detecting unit 100 and a second vibration detecting unit 200 are provided above the object 10. The second vibration detecting unit 200 is separated from the first vibration detecting unit 100 by a distance not smaller than (n-1/4)λ and not larger than (n+1/4)λ (n is an integer of 1 or larger) in the vibration propagating direction. A vibration synthesis unit 300 synthesizes vibrations detected by the first and second vibration detecting units 100 and 200.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a detection apparatus and a detection method.

  In recent years, the presence or absence of defects in an object may be inspected using vibration. For example, Patent Document 1 describes an example of a method for detecting leakage of water pipes using vibration. In this example, two vibration detection units are arranged along the extending direction of the water pipe. Each vibration detection unit includes a vibration sensor and a microphone. The vibration sensor detects vibration of the water pipe, and the microphone detects sound in water inside the water pipe. Patent Document 1 describes that each vibration detection unit generates a common frequency component signal having a common frequency component of the vibration detected by the vibration sensor and the vibration (sound) detected by the microphone. Further, Patent Document 1 describes that the cross-correlation processing is performed on the common frequency component signal of each vibration detection unit. Patent Document 1 describes that leakage of water pipes can be detected based on the result of cross-correlation processing.

JP 2008-51776 A

  In vibration detection, it may be necessary to amplify and detect vibrations of a specific wavelength. The present inventors examined a method for amplifying and detecting vibrations of a specific wavelength in vibration detection.

  An object of the present invention is to amplify and detect vibrations of a specific wavelength in vibration detection.

According to the present invention,
A detection device that amplifies and detects vibration of wavelength λ propagating through an object,
First vibration detecting means disposed on the object;
It is arranged on the object and is located away from the first vibration detection means by a distance (n−1 / 4) λ or more (n + 1/4) λ or less (n is an integer of 1 or more) in the vibration propagation direction. Second vibration detecting means for
Vibration synthesizing means for synthesizing the vibration detected by the first vibration detecting means and the vibration detected by the second vibration detecting means;
Is provided.

According to the present invention,
A detection method for amplifying and detecting a vibration of wavelength λ propagating through an object,
Arranging a first vibration detecting means on the object;
A second vibration detection unit is disposed on the object, and a distance (n−1 / 4) λ or more (n + 1/4) λ or less (n is an integer of 1 or more) in the vibration propagation direction from the first vibration detection unit. ) Position the second vibration detecting means away from each other,
A detection method is provided in which the vibration detected by the first vibration detection means and the vibration detected by the second vibration detection means are combined.

  According to the present invention, vibration of a specific wavelength can be amplified and detected in vibration detection.

It is a figure which shows the structure of the detection apparatus which concerns on embodiment. It is a figure for demonstrating an example of operation | movement of the detection apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

  In the following description, the vibration synthesizer 300 is not a hardware unit configuration but a functional unit block. The vibration synthesizer 300 includes a CPU, a memory of any computer, a program for realizing the components shown in the figure loaded in the memory, a storage medium such as a hard disk for storing the program, and a network connection interface. Realized by any combination of software. There are various modifications of the implementation method and apparatus.

  FIG. 1 is a diagram illustrating a configuration of a detection device according to the embodiment. This detection apparatus amplifies and detects a vibration (first vibration) having a wavelength λ propagating through the object 10. The detection apparatus includes a first vibration detection unit 100, a second vibration detection unit 200, and a vibration synthesis unit 300. The first vibration detection unit 100 is disposed on the object 10. The second vibration detection unit 200 is disposed on the object 10. The second vibration detection unit 200 is located away from the first vibration detection unit 100 in the vibration propagation direction by a distance (n−1 / 4) λ or more (n + 1/4) λ or less (n is an integer of 1 or more). To do. The vibration synthesis unit 300 synthesizes the vibration detected by the first vibration detection unit 100 and the vibration detected by the second vibration detection unit 200. Details will be described below.

  The object 10 is, for example, a base material (for example, a metal base material or a resin base material) located in the vicinity of the vibration member (for example, located in contact with the vibration member or away from the vibration member). More specifically, the object 10 is, for example, a part of a housing having the above-described vibration member in the inner space. In this case, the vibration member described above is, for example, a motor (for example, a machine tool motor or a hard disk motor). Vibration propagates from the vibrating member to the object 10. The vibration propagates through the object 10. In the example shown in the figure, the vibration described above vibrates in the thickness direction of the object 10 (X direction in the figure). The vibration described above propagates in a direction intersecting the thickness direction of the target object 10 (specifically, a direction orthogonal to the thickness direction of the target object 10 and the Z direction in the figure). In this case, the vibration propagating through the object 10 includes, for example, the wavelength of the vibration of the vibration member and the wavelength having the vibration of the resonance frequency of the object 10.

  In the example shown in the figure, the first vibration detection unit 100 is attached to the object 10. Specifically, the first vibration detection unit 100 includes a vibration sensor 110 and a joining member 120. The vibration sensor 110 converts the vibration of the object 10 in the thickness direction (X direction in the figure) into an electrical signal. Specifically, the vibration sensor 110 is, for example, a piezoelectric element. The vibration sensor 110 is fixed to the object 10 via the joining member 120. The joining member 120 is, for example, an adhesive. Note that the method of fixing the vibration sensor 110 to the object 10 is not limited to the example shown in this figure. For example, the vibration sensor 110 may be fixed to the object 10 via a jig or a magnet.

  The second vibration detection unit 200 is attached to the object 10. The second vibration detection unit 200 includes a vibration sensor 210 and a joining member 220. The second vibration detection unit 200 has the same configuration as the first vibration detection unit 100, and the vibration sensor 210 and the joining member 220 have the same configuration as the vibration sensor 110 and the vibration sensor 110, respectively. The vibration sensor 210 converts vibration in the thickness direction (X direction in the figure) of the object 10 into an electric signal in the same manner as the vibration sensor 110.

  The second vibration detection unit 200 is located away from the first vibration detection unit 100 by a distance d in the above-described vibration propagation direction (Z direction in the figure). The distance d satisfies (n−Z1) λ ≦ d ≦ (n + Z2) λ. Z1 and Z2 are both 0 or more. Z1 and Z2 may be equal to each other or may be different from each other. Z1 and Z2 are preferably both small values. Specifically, Z1 and Z2 are, for example, Z1 = Z2 = 1/4, preferably, for example, Z1 = Z2 = 1/8, and more preferably, for example, Z1 = Z2 = 0. In the case described above, the first vibration (vibration with wavelength λ) detected by the first vibration detection unit 100 and the first vibration (vibration with wavelength λ) detected by the second vibration detection unit 200 have substantially the same phase.

  In the example shown in this figure, the above-mentioned distance d is the distance between the centers of the first vibration detection unit 100 and the second vibration detection unit 200. The planar shape of each of the vibration sensor 110 and the vibration sensor 210 is, for example, a circle.

  The vibration synthesis unit 300 receives a signal indicating the vibration detected by the first vibration detection unit 100 and a signal indicating the vibration detected by the second vibration detection unit 200. Then, the vibration synthesizer 300 synthesizes these vibrations. As described above, the first vibration (vibration with wavelength λ) detected by the first vibration detection unit 100 and the first vibration (vibration with wavelength λ) detected by the second vibration detection unit 200 have substantially the same phase. For this reason, the vibration generated by the vibration synthesizer 300 has a strong component of wavelength λ due to wave interference.

  The wavelength λ can be a desired wavelength. For example, the wavelength λ is a wavelength of the resonance frequency of the object 10 or an integer multiple of the resonance frequency. In this case, the vibration generated by the vibration synthesizer 300 has a strong vibration component of the resonance frequency of the object 10 or a harmonic component thereof.

  FIG. 2 is a diagram for explaining an example of the operation of the detection apparatus shown in FIG. This figure (a) is a figure which shows the frequency spectrum of the vibration which the 1st vibration detection part 100 detected. This figure (b) is a figure which shows the frequency spectrum of the vibration which the vibration synthetic | combination part 300 produced | generated. In the example shown in the figure, the detection device amplifies vibration having a frequency of 3 kHz. The wavelength λ of vibration can be determined based on the relationship of λ = V / f (f: frequency of vibration). In this case, V is the propagation speed of vibration and is a value unique to the object 10 (FIG. 1).

  As shown in FIG. 2B, the vibration synthesizer 300 has a strong amplitude of 3 kHz. Specifically, as described with reference to FIG. 1, the first vibration (vibration with wavelength λ) detected by the first vibration detection unit 100 and the first vibration (vibration with wavelength λ) detected by the second vibration detection unit 200. ) Are almost in phase. Therefore, when the vibration detected by the first vibration detecting unit 100 and the vibration detected by the second vibration detecting unit 200 are combined in the vibration combining unit 300, the amplitude of the wavelength λ (the wavelength of 3 kHz in the example shown in FIG. 2). Interfere to strengthen each other. As a result, as shown in FIG. 2B, the vibration synthesizer 300 has a strong amplitude of 3 kHz.

  As described above, according to the present embodiment, the detection device amplifies the vibration of the wavelength λ. The first vibration detection unit 100 and the second vibration detection unit 200 are located at a distance (n−1 / 4) λ or more and (n + 1/4) λ or less apart from each other in the vibration propagation direction. The vibration synthesis unit 300 synthesizes the vibration detected by the first vibration detection unit 100 and the vibration detected by the second vibration detection unit 200. Thereby, the vibration generated by the vibration synthesizer 300 has a strong component of the wavelength λ.

The detection apparatus shown in FIG. 1 was produced (Example 1). Specifically, the object 10 was a brass substrate (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation velocity V = 4.65 × 10 ³ m / s). Both the vibration sensor 110 and the vibration sensor 210 are piezoelectric vibration sensors. A vibration with a frequency f = 3.00 × 10 ³ Hz was applied to the object 10 with a vibrator. The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 1.55 m.

The detection apparatus shown in FIG. 1 was produced (Example 2). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the object 10 includes a Teflon (registered trademark) base material (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation velocity V = 1.52 × 10 ³ m / s). did. The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 0.507 m.

The detection apparatus shown in FIG. 1 was produced (Example 3). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the object 10 was a titanium substrate (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation speed V = 6.10 × 10 ³ m / s). The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 2.03 m.

The detection apparatus shown in FIG. 1 was produced (Example 4). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the object 10 was a nickel base (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation velocity V = 5.64 × 10 ³ m / s). The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 1.88 m.

The detection apparatus shown in FIG. 1 was produced (Example 5). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the object 10 was a polyvinyl chloride substrate (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation velocity V = 2.39 × 10 ³ m / s). The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 0.797 m.

The detection apparatus shown in FIG. 1 was produced (Example 6). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the object 10 was a copper base material (length 3000 mm × width 300 mm × thickness 3.0 mm, vibration propagation velocity V = 4.65 × 10 ³ m / s). The center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 was set to d = λ (λ = V / f). In this embodiment, the distance d is d = 1.55 m.

  The detection apparatus shown in FIG. 1 was produced (Example 7). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the center-to-center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 is d = (3/4) λ (λ = V / f). In this embodiment, the distance d is d = 1.16 m.

  The detection apparatus shown in FIG. 1 was produced (Example 8). The detection apparatus according to the present embodiment has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 is set to d = (9/10) λ (λ = V / f). In this embodiment, the distance d is d = 1.40 m.

  A detection device different from the detection device shown in FIG. 1 was produced (Comparative Example 1). The detection apparatus according to this comparative example has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, only the first vibration detection unit 100 is arranged on the object 10. On the other hand, the second vibration detection unit 200 was not disposed on the object 10.

  A detection device different from the detection device shown in FIG. 1 was produced (Comparative Example 2). The detection device according to this comparative example has the same configuration as the detection device according to comparative example 1 except for the following points. Specifically, the vibration sensor 110 is a capacitive vibration sensor. In the comparative example, the first vibration detection unit 100 does not include the joining member 120. The vibration sensor 110 was disposed away from the object 10.

  A detection device different from the detection device shown in FIG. 1 was produced (Comparative Example 3). The detection apparatus according to this comparative example has the same configuration as the detection apparatus according to the first embodiment except for the following points. Specifically, the center distance d between the first vibration detection unit 100 and the second vibration detection unit 200 is 20 cm (d << λ (λ: 1.55 m)).

  The following evaluation was performed in each of Examples 1 to 8 and Comparative Examples 1 to 3. For Comparative Examples 1 and 2, the following evaluations 2 and 3 were not performed.

The vibration detected by the first vibration detection unit 100 was subjected to fast Fourier transform. In the frequency spectrum obtained in this case, a vibration acceleration level of 3.00 × 10 ³ Hz was measured (Evaluation 1).

The vibration detected by the second vibration detection unit 200 was fast Fourier transformed. In the frequency spectrum obtained in this case, a vibration acceleration level of 3.00 × 10 ³ Hz was measured (Evaluation 2).

The vibration generated by the vibration synthesizer 300 was subjected to fast Fourier transform. In the frequency spectrum obtained in this case, a vibration acceleration level of 3.00 × 10 ³ Hz was measured (Evaluation 3).

Based on the measurement result of evaluation 3, Pa / Pb was calculated (evaluation 4). Pa represents a vibration acceleration level of 3.00 × 10 ³ Hz in the frequency spectrum. Pb is the maximum value of the vibration acceleration level in the frequency spectrum from 2.00 × 10 ³ Hz to 4.00 × 10 ³ Hz (excluding the vibration acceleration level of 3.00 × 10 ³ Hz).

  It was determined whether Pa / Pb calculated in Evaluation 4 was 2.0 or more (≧ 2.0) or less than 2.0 (<2.0) (Evaluation 5).

Table 1 shows each result of Examples 1-8 and Comparative Examples 1-3. In Table 1, the units of evaluations 1 to 3 are all dB.

As shown in Table 1, in each of Examples 1 to 8, Pa / Pb ≧ 2.0 in Evaluation 5. On the other hand, in Comparative Examples 1 to 3, in evaluation 5, Pa / Pb <2.0. Thus, in Examples 1 to 8, it can be said that the amplification of the vibration of the desired frequency (f = 3.00 × 10 ³ Hz) was successfully realized.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

DESCRIPTION OF SYMBOLS 10 Object 100 1st vibration detection part 110 Vibration sensor 120 Joining member 200 2nd vibration detection part 210 Vibration sensor 220 Joining member 300 Vibration synthetic | combination part

Claims (4)

A detection device that amplifies and detects vibration of wavelength λ propagating through an object,
First vibration detecting means disposed on the object;
It is arranged on the object and is located away from the first vibration detection means by a distance (n−1 / 4) λ or more (n + 1/4) λ or less (n is an integer of 1 or more) in the vibration propagation direction. Second vibration detecting means for
Vibration synthesizing means for synthesizing the vibration detected by the first vibration detecting means and the vibration detected by the second vibration detecting means;
A detection device comprising: The detection device according to claim 1,
The second vibration detection means is a detection device located at a distance nλ away from the first vibration detection means in the propagation direction. The detection device according to claim 1 or 2,
The wavelength λ is a detection device that is a wavelength of a resonance frequency of the object or an integer multiple of the resonance frequency. A detection method for amplifying and detecting a vibration of wavelength λ propagating through an object,
Arranging a first vibration detecting means on the object;
A second vibration detection unit is disposed on the object, and a distance (n−1 / 4) λ or more (n + 1/4) λ or less (n is an integer of 1 or more) in the vibration propagation direction from the first vibration detection unit. ) Position the second vibration detecting means away from each other,
A detection method for combining the vibration detected by the first vibration detection means and the vibration detected by the second vibration detection means.

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