Vibration detection device, assistance system for anomaly detection and vibration detection method

Abstract

A vibration detection device 2 comprises a vibration detector 21, which detects a vibration generated in a rolling bearing B and converts the vibration into an analog signal A, and a sampler 22, which performs a sampling of the analog signal A to convert the analog signal A into a digital signal D. During vibration, a repetition unit A1, including a first vibration section Z1, in which the vibration occurs at a predetermined first frequency F1, and a second section Z2 following the first vibration section Z1 at a predetermined repetition period Tr, is repeated when a fault is generated in the rolling bearing B. The sampler 22 performs a sampling of the analog signal at a sampling frequency that is less than twice the first frequency.

Description

TECHNICAL FIELD

[0001] The present invention relates to a vibration detection device, an abnormality detection assistance system, and a vibration detection method for detecting abnormalities of a rolling bearing. STATE OF THE ART

[0002] Conventionally, an abnormality identification device is known that identifies an abnormality in a bearing by attaching a vibration detection element to a bearing device of a railway vehicle, sampling a detected vibration signal, obtaining an envelope, and performing frequency analysis by FFT on the envelope (see, for example, paragraphs 0025 and 0026 of Patent Literature 1 (PTL 1)).

[0003] According to the description in paragraph 0026 of PTL 1, since the maximum frequency that can undergo Fourier transformation (Nyquist frequency) is determined according to the sampling time, it is preferable that a frequency equal to or higher than the Nyquist frequency is not included in an oscillation signal. The Nyquist frequency is a frequency 1 / 2 the sampling frequency. Therefore, the sampling frequency must be at least twice the highest frequency contained in the oscillation signal to prevent a frequency equal to or higher than the Nyquist frequency from being included in the oscillation signal. LIST OF REFERENCESPATENT LITERATURE

[0004] PTL 1: Japanese Unexamined Patent Application Publication No. 2004-212225 SUMMARY OF THE INVENTION

[0005] However, sampling at a sampling frequency twice or more than the highest frequency contained in the vibration signal increases the cost of elements such as sensors and an analog-to-digital converter that perform the sampling, resulting in an increase in the cost of a vibration detection device for detecting vibration.

[0006] An object of the present invention is to provide a vibration detection device, an anomaly detection assistance system, and a vibration detection method that can easily reduce the cost of a vibration detection device for detecting anomalies in a rolling bearing.

[0007] A vibration detection device according to one aspect of the present invention includes: a vibration detector that detects vibration generated in a rolling bearing and converts the vibration into an analog signal; and a sampler that performs sampling on the analog signal to convert the analog signal into a digital signal. In the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section are repeated at a predetermined repetition period when a fault is generated in the rolling bearing, and the sampler performs sampling on the analog signal at a sampling frequency lower than twice the first frequency.

[0008] An anomaly detection assistance system according to one aspect of the present invention includes: a digital signal acquirer that acquires the digital signal from the above-described vibration detection device; an envelope detector that detects an envelope of a vibration waveform based on the digital signal; and a frequency analyzer that performs frequency analysis on the envelope to calculate an analysis value for each frequency component.

[0009] A vibration detection method according to one aspect of the present invention includes detecting vibration generated in a rolling bearing and converting the vibration into an analog signal; and sampling the analog signal to convert the analog signal into a digital signal. In the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section with a predetermined repetition period is repeated when a fault is generated in the rolling bearing, and in the sampling, the analog signal is sampled at a sampling frequency lower than twice the first frequency. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram illustrating an example of an abnormality detection assistance system including a vibration detection device according to an embodiment of the present invention. Fig. 2 is a block diagram showing an example of an electrical configuration of the Fig. 1 represents the assistance system for detecting anomalies. Fig. Figure 3 is an explanatory diagram showing an example of a processing flow of the anomaly detection assistance system. Fig. Figure 4 is a waveform diagram showing a typical example of an analog signal indicating vibration in a case where a fault is generated in a rolling bearing. Fig. 5 is an enlarged diagram of a Fig. 4 shown repeating unit. Fig. 6 is an explanatory diagram for describing the structure of the rolling bearing. Fig. 7 is an explanatory diagram for describing scanning performed by a scanner. Fig. Figure 8 is an explanatory diagram for describing a folding caused by scanning. Fig. Figure 9 is a waveform diagram showing an example of an envelope waveform. Fig. Figure 10 is an explanatory diagram showing an analysis value for each frequency component in a graph. DESCRIPTION OF EMBODIMENTS

[0010] Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the drawings, components with the same reference numerals have the same configuration, and descriptions of the same components may be omitted. Fig. 1 is a block diagram illustrating an example of an abnormality detection assistance system including a vibration detection device according to an embodiment of the present invention.

[0011] One in Fig. The abnormality detection assistance system 1 shown in FIG. 1 includes a vibration detection device 2 and an abnormality detection assistance device 3. The vibration detection device 2 is mounted on, for example, a casing of a motor M including a rolling bearing B as an abnormality detection target. Alternatively, the vibration detection device 2 may be mounted on a casing or the like of a mechanical device including the motor M. The vibration detection device 2 can detect vibrations generated in the rolling bearing B when mounted on the motor M or the like including the rolling bearing B.

[0012] The rolling bearing B includes an outer ring B1, an inner ring B2, and a rolling element B3. Note that the rolling bearing B is not limited to being used for the motor M and can be used for various applications. The vibration detection device 2 only needs to be mounted on a part where vibrations generated in the rolling bearing are transmitted.

[0013] Fig. 2 is a block diagram showing an example of an electrical configuration of the Fig. 1 represents the assistance system for detecting anomalies 1. The Fig. The anomaly detection assistance system 1 shown in Figure 2 includes the vibration detection device 2 and the anomaly detection assistance device 3.

[0014] The vibration detection device 2 includes a vibration detector 21, a scanner 22, and a communicator 23. The vibration detector 21 and the scanner 22 may be integrally configured as, for example, an acceleration sensor 20 or the like.

[0015] The vibration detector 21 detects vibration, converts the vibration into an analog signal A, and outputs the analog signal A to the scanner 22. The vibration detector 21 can detect vibration as acceleration, can detect vibration in one axis, or can detect vibration in the X-axis, Y-axis, and Z-axis directions orthogonal to each other, and output analog signals Ax, Ay, and Az representing the vibration in the X-axis, Y-axis, and Z-axis directions as an analog signal A to the scanner 22.

[0016] Acceleration corresponds to an example of information indicating vibration. Note that vibration detector 21 only needs to be capable of detecting vibration and is not limited to detecting vibration based on acceleration. For example, vibration detector 21 can detect vibration based on velocity or can detect vibration based on displacement.

[0017] Sampler 22 samples analog signal A to convert it into a digital signal D and outputs the digital signal D to communicator 23. Sampler 22 is configured, for example, as an analog-to-digital converter. Sampler 22 samples analog signal A at a sampling frequency Fs.

[0018] The communicator 23 is a communication interface circuit capable of wirelessly communicating with the anomaly detection assist device 3. The communicator 23 transmits the digital signal D to the anomaly detection assist device 3 via wireless communication.

[0019] The anomaly detection assistance device 3 is configured using, for example, a personal computer. The anomaly detection assistance device 3 includes, for example, a calculator 31, a communicator 32 (a digital signal acquirer), a display 33, a keyboard 34, and a mouse 35.

[0020] The communicator 32 is a communication interface circuit capable of wirelessly communicating with the communicator 23 of the vibration detection device 2. The communicator 32 acquires the digital signal D transmitted from the vibration detection device 2 and transmits the digital signal D to the computer 31. Various wireless communication methods, such as WiFi (registered trademark) and Bluetooth (registered trademark), can be used as the communication method of the communicators 23 and 32.

[0021] Note that the communicators 23 and 32 are not limited to the example of performing wireless communication and may perform wired communication. Alternatively, the digital signal D output from the scanner 22 may be stored in a storage medium such as a memory card and read by the anomaly detection assisting device 3, so that the anomaly detection assisting device 3 acquires the digital signal D. In this case, a reading device that reads the storage medium corresponds to one example of the digital signal acquirer.

[0022] The vibration detection device 2 and the anomaly detection assistance device 3 can be configured as an integrated device. In this case, the communicators 23 and 32 are not necessary, and the digital signal D output from the sampler 22 can be input directly or indirectly to the computer 31. In this case, the computer 31 corresponds to an example of the digital signal acquirer.

[0023] The computer 31 is configured using, for example, a microcomputer. The computer 31 includes, for example, a central processing unit (CPU) that performs predetermined arithmetic processing, a random access memory (RAM) that temporarily stores data, a non-volatile storage device such as a hard disk drive (HDD) or a solid-state drive (SSD), and peripheral circuits for these components.

[0024] Then, the computer 31 functions as an envelope detector 311, a frequency analyzer 312, and an anomaly determiner 313 by, for example, executing an anomaly detection assistance program previously stored in the above-described storage device.

[0025] The envelope detector 311 detects an envelope of an oscillation waveform based on the digital signal D.

[0026] The frequency analyzer 312 performs frequency analysis on the envelope detected by the envelope detector 311 and calculates an analysis value for each frequency component.

[0027] The anomaly determiner 313 determines that there is an anomaly when the magnitude of the analysis value for each frequency component calculated by the frequency analyzer 312 exceeds a preset reference value in a reference frequency range corresponding to a frequency range including a repetition frequency Fr that is an inverse of a repetition period Tr to be described later.

[0028] Next, an operation of the Fig. 1 described assistance system for detecting anomalies 1. Fig. 3 is an explanatory diagram showing an example of a processing flow in the anomaly detection assistance system 1. In Fig. 3, transmission and reception of the digital signal D by the communicators 23 and 32 are not shown.

[0029] First, the vibration detector 21 detects a vibration generated in the rolling bearing B, converts the vibration into an analog signal A, and outputs the analog signal A to the scanner 22.

[0030] Fig. 4 is a waveform diagram showing a typical example of the analog signal A indicating vibration in a case where a fault is generated in the rolling bearing B. It is known that in a case where a fault is generated in the rolling bearing B, an obtained vibration waveform includes a repeating unit A1 repeated at an interval of the repeating period Tr, as shown in Fig. 4 is shown.

[0031] Fig. 5 is an enlarged diagram of an example of the Fig. 4. The repeating unit A1 includes a first section Z1 in which an oscillation with a first frequency F1 is generated, and a second section Z2 following the first section Z1. The second section Z2 is a section in which the oscillation converges in the first section Z1. The amplitude of the analog signal A in the second section Z2 is, for example, 1 / 10 or less of the maximum amplitude of the analog signal A in the first section Z1.

[0032] The frequency of the analog signal A in the first section Z1 is the first frequency F1. When the frequency of the analog signal A varies in the first section Z1, the maximum frequency of the variation range can be set as the first frequency F1.

[0033] It is known that the repetition frequency Fr, which is the inverse of the repetition period Tr, is determined by the structure of the rolling bearing B, the rotational speed and the position of the fault. Fig. 6 is an explanatory diagram for describing the structure of the rolling bearing B. When the rotation frequency of the rolling bearing B is defined as Fb, the pitch circle diameter of the rolling bearing B is defined as Da, the diameter of the rolling element B3 is defined as Db, the contact angle of the rolling element B3 is defined as R, and the number of rolling elements is defined as N, the repetition frequencies Fr in a case where faults are generated in the outer ring B1 and the inner ring B2 are expressed by the following formulas (1) and (2), respectively.

[0034] Repetition frequency in a case where a fault is generated in an outer ring B1: Fr=(N / 2)×Fb×{1(Db / Da)cosR} (1)

[0035] Repetition frequency in a case where a fault is generated in an inner ring B2: Fr=(N / 2)×Fb×{1(Db / Da)cosR} (2)

[0036] If one refers to Fig. 3, the sampler 22 then samples the analog signal A at the sampling frequency Fs to convert the analog signal A into the digital signal D. Fig. Fig. 7 is an explanatory diagram for describing a scanning performed by the scanner 22. In Fig. In Figure 7, the waveform of analog signal A is indicated by a dashed line, and the waveform of digital signal D is indicated by a solid line. The sampling points are indicated by × marks.

[0037] The sampling frequency Fs is less than twice the first frequency F1, which is the frequency of the analog signal A in the first section Z1. Therefore, the sampling frequency Fs is in a state of subsampling relative to the analog signal A in the first section Z1.

[0038] A sampling period Ts, which is the inverse of the sampling frequency Fs, is shorter than 1 / 2 of the repetition period Tr. Therefore, the sampling frequency Fs is higher than twice the repetition frequency Fr. The sampling frequency Fs is desirably as high as possible within a range less than twice the first frequency F1. For example, it is more preferable that the sampling period Ts is shorter than 1 / 4 of the repetition period Tr and the sampling frequency Fs is greater than four times the repetition frequency Fr.

[0039] Fig. Figure 8 is an explanatory diagram for describing a convolution caused by sampling the analog signal A at the sampling frequency Fs which is lower than twice the first frequency F1. Fig. In Figure 8, the analog signal A is represented by a frequency spectrum, with a horizontal axis representing frequency and a vertical axis representing signal intensity. 0.5 fs is the Nyquist frequency.

[0040] As it is in Fig. As shown in Figure 8, a portion of the analog signal A representing the oscillation, in which a frequency higher than the Nyquist frequency (0.5 fs), is convolved to a frequency lower than the Nyquist frequency (0.5 fs) and sampled. As a result, as shown in a convolved diagram E, the signals with different frequencies are superimposed on each other, and the sum of the intensities of the signals becomes the waveform indicated by the sampled digital signal D.

[0041] As described above, when signals of different frequencies are folded and superimposed, the frequency, waveform, and the like of the vibration signal cannot be correctly detected, resulting in vibration noise commonly referred to as "folding noise" (or "aliasing") or the like, and measures to prevent such folding have become necessary. However, because the anomaly detection assistance system 1 detects the envelope, that is, the overall intensity change, the sum of the intensities of signals of a plurality of frequencies can be regarded as the intensity of a signal of one frequency without any problem.

[0042] Next, the envelope detector 311 performs offset removal processing, removing a DC component not to be analyzed from the digital signal D generated by the sampler 22 to generate a sample waveform D1 (step S1). If there is an offset in the signal waveform represented by the digital signal D, the shape of the envelope is changed. Therefore, a target waveform cannot be obtained. As a result, the detection sensitivity for anomaly detection decreases. Therefore, the envelope detector 311 preferably performs offset removal processing (step S1).

[0043] Next, the envelope detector 311 performs, for example, a Hilbert transform (step S2) on the sampling waveform D1 to obtain an envelope of the signal waveform represented by the sampling waveform D1, and generates an envelope waveform D2 representing the envelope.

[0044] Fig. Figure 9 is a waveform diagram showing an example of the envelope waveform D2. In Fig. 9, the envelope waveform D2 is indicated by a solid line, and an envelope waveform Dx obtained when sampling is performed with the sampling frequency Fs set to twice or more of the first frequency F1 is indicated by a dashed line.

[0045] For the envelope waveform D2, the sampling frequency Fs is less than twice the first frequency F1 and does not satisfy the sampling theorem. As a result, the envelope waveform Dx, for which the sampling frequency Fs satisfies the sampling theorem, and the envelope waveform D2 are different waveforms in the first section Z1. However, although the envelope waveform D2 is a different waveform from the envelope waveform Dx, the envelope waveform D2 retains the characteristic that the oscillation waveform appears similar to the envelope waveform Dx in the interval of the repetition period Tr.

[0046] That is, even the envelope waveform D2, which does not satisfy the sampling theorem, contains the frequency component of the repetition frequency Fr, which is the inverse of the repetition period Tr.

[0047] Next, the envelope detector 311 performs processing by taking, for example, an absolute value of a complex number for the envelope waveform D2 to generate an envelope waveform D3 (step S3).

[0048] Next, the frequency analyzer 312 performs offset removal processing to remove a DC component not to be analyzed from the envelope waveform D3 generated by the envelope detector 311, thereby generating an analysis target waveform D4 (step S4). If a DC component (offset) exists in the envelope waveform D3, a strong peak above 0 to 2 Hz appears when the fast Fourier transform (FFT) is performed in step S5. Therefore, even if a peak of 2 Hz or less exists due to a fault in the rolling bearing B, it is not possible to determine whether the peak is due to the fault or the offset, and there is a possibility that an abnormality in the rolling bearing B cannot be determined.

[0049] Therefore, it is preferable that the frequency analyzer 312 performs the offset removal processing of step S4 to remove the DC component from the envelope D3.

[0050] Next, the frequency analyzer 312 performs frequency analysis by a fast Fourier transform (FFT) based on the analysis target waveform D4 to calculate an analysis value D5 for each frequency component (step S5).

[0051] Fig. Figure 10 is an explanatory diagram showing the analysis value D5 for each frequency component in a graph. Fig. 10 shows an analysis value Dy based on the envelope waveform Dx obtained when sampling is performed at the sampling frequency Fs set, as a compared target, to twice or more of the first frequency F1.

[0052] As it is in Fig. 10, even in the analysis values ​​D5 obtained when the sampling frequency Fs is less than twice the first frequency F1, that is, when the sampling frequency Fs is in a state of sub-sampling, a peak appears at the repetition frequency Fr similar to the analysis value Dy for which the sampling frequency Fs is twice or more of the first frequency F1 and satisfies the sampling theorem.

[0053] The frequency analyzer 312 can display the analysis value D5 for each frequency component on the display 33, for example as a graph on a two-dimensional plane in which one axis represents the frequency and the other axis represents the analysis value, as shown in Fig. 10. A user can detect an abnormality in the rolling bearing B by viewing the graphically displayed analysis value D5 to check whether a peak appears at the repetition frequency Fr.

[0054] Next, the anomaly determiner 313 determines that the rolling bearing B is in an abnormal condition if the magnitude of the analysis value D5 for each frequency component exceeds a preset reference value within a reference frequency range, which is a frequency range including the repetition frequency Fr. The reference value can be obtained experimentally, for example, and adjusted as appropriate. The anomaly determiner 313 can display the determination result on the display 33.

[0055] The reference frequency range includes an outer ring frequency range including the repetition frequency Fr in a case where a fault is generated in the outer ring B1, that is, an outer ring frequency range set in association with the outer ring B1, and an inner ring frequency range including the repetition frequency Fr in a case where a fault is generated in the inner ring B2, that is, an inner ring frequency range set in association with the inner ring B2.

[0056] As the outer ring frequency range, for example, a value that allows a measurement error of the vibration detection device 2, a calculation error of the envelope detector 311 and the frequency analyzer 312, and the like with respect to the repetition frequency Fr in a case where a fault is generated in the outer ring B1, which is expressed by an expression (1), can be used. As the inner ring frequency range, for example, a value that allows a measurement error of the vibration detection device 2, a calculation error of the envelope detector 311 and the frequency analyzer 312, and the like with respect to the repetition frequency Fr in a case where a fault is generated in the inner ring B2, which is expressed by an expression (2), can be used.

[0057] The abnormality determiner 313 may determine that the outer ring B1 of the rolling bearing B is in an abnormal state when the magnitude of the analysis value D5 for each frequency component exceeds the reference value within the outer ring frequency range, and may determine that the inner ring B2 of the rolling bearing B is in an abnormal state when the magnitude of the analysis value D5 for each frequency component exceeds the reference value within the inner ring frequency range.

[0058] As described above, according to the vibration detection device 2 and the abnormality detection assistance system 1, it is possible to detect the abnormality in the rolling bearing B while causing the sampling frequency Fs to be in a sub-sampling state, that is, lower than twice the first frequency F1. As a result, the sampler 22 can be configured using an analog-to-digital converter or the like, which has a low sampling frequency Fs and is thus inexpensive. Therefore, it is easy to reduce the cost of the vibration detection device 2 that detects the abnormality in the rolling bearing B and the abnormality detection assistance system 1 using the vibration detection device 2.

[0059] Note that the anomaly detection assistance system 1 does not necessarily include the anomaly determiner 313. The envelope detector 311 may perform a Hilbert transform (step S2) on the digital signal D without performing the offset removal processing (step S1). The envelope detector 311 only needs to be able to obtain the envelope, and the method for obtaining the envelope is not limited to the Hilbert transform.

[0060] The envelope detector 311 does not necessarily perform the processing of taking an absolute value of the complex number (step S3), and the frequency analyzer 312 may perform the offset removal processing (step S4) on the envelope waveform D2. The frequency analyzer 312 may perform the fast Fourier transform (step S5) on the envelope waveform D2 or the envelope waveform D3 without performing the offset removal processing (step S4).

[0061] That is, a vibration detection device according to one aspect of the present invention includes: a vibration detector that detects vibration generated in a rolling bearing and converts the vibration into an analog signal; and a sampler that performs sampling on the analog signal to convert the analog signal into a digital signal. In the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section is repeated at a predetermined repetition period when a fault is generated in the rolling bearing, and the sampler performs sampling on the analog signal at a sampling frequency lower than twice the first frequency.

[0062] A vibration detection method according to one aspect of the present invention includes detecting vibration generated in a rolling bearing and converting the vibration into an analog signal; and sampling the analog signal to convert the analog signal into a digital signal. In the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section is repeated at a predetermined repetition period when a fault is generated in the rolling bearing, and in the sampling, the analog signal is sampled at a sampling frequency lower than twice the first frequency.

[0063] According to these configurations, it is sufficient that sampling can be performed at a low frequency less than twice the first frequency, so that a low-cost element can be used as the element for performing sampling. As a result, it is easy to reduce the cost of the vibration detection device that detects the anomaly in the rolling bearing.

[0064] The sampling frequency is preferably lower than twice the first frequency.

[0065] According to this configuration, it is clear that sampling is performed at a low frequency, which does not satisfy the sampling theorem with respect to the first frequency.

[0066] A sampling period is preferably shorter than 1 / 2 of the repetition period.

[0067] According to the configuration, the sampled digital signal contains a frequency component of the repetition frequency, which is the inverse of the repetition period.

[0068] An anomaly detection assistance system according to one aspect of the present invention includes: a digital signal acquirer that acquires the digital signal from the above-described vibration detection device; an envelope detector that detects an envelope of a vibration waveform based on the digital signal; and a frequency analyzer that performs frequency analysis on the envelope to calculate an analysis value for each frequency component.

[0069] According to the configuration, an analysis value is obtained for each frequency component relative to the envelope of the digital signal sampled at a low frequency less than twice the first frequency. By obtaining the analysis value for each frequency component, it is easy to detect the anomaly in the rolling bearing from the analysis value.

[0070] It is preferable that the anomaly detection assistance system further includes an anomaly determiner that determines an anomaly when a magnitude of the analysis value for each frequency component exceeds a preset reference value in a reference frequency range, which is a frequency range including a repetition frequency obtained by inverting the repetition period.

[0071] According to the configuration, it is possible to detect an anomaly automatically.

[0072] It is preferable that the reference frequency range includes an outer ring frequency range set in association with an outer ring of the rolling bearing, and the abnormality determiner determines that the outer ring is abnormal when a magnitude of the analysis value for each frequency component exceeds the reference value within the outer ring frequency range.

[0073] According to the configuration, it is possible to automatically detect an anomaly in the outer ring of the rolling bearing.

[0074] It is preferable that the reference frequency range includes an inner ring frequency range set in association with an inner ring of the rolling bearing, and the abnormality determiner determines that the inner ring is in an abnormal state when a magnitude of the analysis value for each frequency component exceeds the reference value within the inner ring frequency range.

[0075] According to this configuration, it is possible to automatically detect an anomaly in the inner ring of the rolling bearing.

[0076] It is preferable that the anomaly detection assistance system continues to include the vibration detection device.

[0077] According to this configuration, the vibration detection device is included in the anomaly detection assistance system.

[0078] It should be noted that the specific embodiment or example described in the DESCRIPTION OF EMBODIMENTS merely clarifies the technical content of the present invention, and the present invention should not be construed in a narrow sense by being limited to such specific examples. LIST OF REFERENCE SYMBOLS 1 assistance system for detecting anomalies 2 Vibration detection device 3 Anomaly detection assistance device 20 Accelerometer 21 Vibration detector 22 scanners 23 Communicator 31 computers (digital signal acquirers) 32 Communicator (digital signal acquirer) 33 Advertisement 311 Envelope detector 312 Frequency Analyzer 313 Anomaly Determiner A Analog signal A1 repeat unit B Rolling bearings B1 outer ring B2 inner ring B3 rolling elements D Digital signal D1 sampling waveform D2, D3 envelope waveform D4 Analysis target waveform D5 Analysis value F1 First Frequency Fr Refresh rate Fs sampling frequency M engine Tr repeat period Ts sampling period Z1 First Section Z2 Second Section QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2004-212225

[0004]

Claims

[1] Vibration detection device comprising: a vibration detector that detects a vibration generated in a rolling bearing and converts the vibration into an analog signal; and a sampler that performs sampling on the analog signal to convert the analog signal into a digital signal, wherein in the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section is repeated at a predetermined repeating period when a fault is generated in the rolling bearing, and the sampler performs sampling on the analog signal at a sampling frequency that is lower than twice the first frequency. [2] The vibration detection device according to claim 1, wherein a period of sampling is shorter than 1 / 2 of the repetition period. [3] Anomaly detection assistance system comprising: a digital signal acquirer that acquires the digital signal from the vibration detection device according to claim 1 or 2; an envelope detector that detects an envelope of a vibration waveform based on the digital signal; and a frequency analyzer that performs frequency analysis on the envelope to calculate an analysis value for each frequency component. [4] An anomaly detection assistance system according to claim 3, further comprising: an anomaly determiner that determines an anomaly when a magnitude of the analysis value for each frequency component exceeds a preset reference value in a reference frequency range, which is a frequency range including a repetition frequency obtained by inverting the repetition period. [5] Anomaly detection assistance system according to claim 4, wherein the reference frequency range includes an outer ring frequency range which is set in connection with an outer ring of the rolling bearing, and The anomaly determiner determines that the outer ring is in an abnormal state when a magnitude of the analysis value for each frequency component exceeds the reference value within the outer ring frequency range. [6] Anomaly detection assistance system according to claim 4, wherein the reference frequency range includes an inner ring frequency range which is set in connection with an inner ring of the rolling bearing, and The anomaly determiner determines that the inner ring is in an abnormal state when a magnitude of the analysis value for each frequency component exceeds the reference value within the inner ring frequency range. [7] An anomaly detection assistance system according to claim 3, further comprising: the vibration detection device. [8] Vibration detection method comprising: Detecting a vibration generated in a rolling bearing and converting the vibration into an analog signal; and Sampling the analog signal to convert the analog signal into a digital signal, where in the vibration, a repeating unit including a first vibration section in which vibration occurs at a predetermined first frequency and a second section following the first vibration section is repeated at a predetermined repeating period when a fault is generated in the rolling bearing, and when sampling, the analog signal is sampled at a sampling frequency that is lower than twice the first frequency.

Images