Rotational speed detection device and measurement method for rotating equipment

Abstract

This application provides a rotational speed detection device and its measurement method for rotating equipment. The rotational speed detection device includes: a housing; a magnetic flux leakage probe disposed on the top side of the housing and capable of extending and retracting relative to the housing; a main PCB disposed within the housing; and a flexible PCB, one end of which is electrically connected to the magnetic flux leakage probe and the other end of which is electrically connected to the main PCB. The measurement method obtains the spectrum and KPI value based on the raw magnetic flux leakage data; and determines different rotational speed calculation methods based on the KPI value. The magnetic flux leakage probe of the rotational speed detection device is flexible and retractable, has high sensitivity, and the measurement method has high robustness and wide applicability.

Description

Technical Field

[0001] This application relates to the field of rotating equipment condition monitoring and fault diagnosis technology. Specifically, this application relates to a rotational speed detection device and a measurement method for rotating equipment. Background Technology

[0002] In the context of Industry 4.0, the market demand for lifecycle maintenance of rotating equipment is constantly rising, and the requirements for the accuracy of condition monitoring of rotating equipment are also gradually increasing. For rotating equipment, vibration signals are usually used to determine the condition of bearings and other mechanical components. However, the accuracy of speed signals is crucial to the accuracy of condition monitoring and fault diagnosis. Sometimes, a small speed error combined with a narrow alarm bandwidth can cause a defective bearing outer ring to fail to trigger an alarm, thus missing the optimal downtime for maintenance and potentially leading to more serious unplanned downtime losses.

[0003] Rotating equipment can be, but is not limited to, electric motors. Currently, most existing electric motors on the market, such as drive motors for fans and pumps, are asynchronous motors directly driven by grid power. Non-invasive speed detection for these types of motors has always been a hot topic in the research field.

[0004] Currently, induction coils are commonly used to detect the leakage magnetic field of motors, but they are generally quite large. The installation position of the induction coil is usually selected at the shaft end or outside the machine casing. The leakage magnetic field at the actual measurement position is weak, and the obtained voltage signal is also weak, which is not conducive to subsequent data analysis. Summary of the Invention

[0005] To address the above technical problems, this application provides a speed detection device and measurement method for rotating equipment.

[0006] In one aspect, embodiments of this application provide a rotational speed detection device for a rotating device, comprising: a housing; a magnetic flux leakage probe disposed on the top side of the housing and extendable and retractable relative to the housing; a main PCB disposed within the housing; and a flexible PCB, one end of which is electrically connected to the magnetic flux leakage probe and the other end of which is electrically connected to the main PCB.

[0007] According to some embodiments of this application, the housing is provided with a slide rail extending along the extension and retraction direction of the magnetic flux leakage probe, and a slider movable along the slide rail; the flexible PCB is disposed on the slider, and the magnetic flux leakage probe extends and retracts relative to the housing by the movement of the slider on the slide rail.

[0008] According to some embodiments of this application, the rotational speed detection device further includes: a clamping assembly disposed on the housing; the clamping assembly includes: a clamping gear, a first clamping member, and a second clamping member.

[0009] The first clamping member includes: a first screw meshing with the clamping gear and a first clamping abutment disposed at one axial end of the first screw; the second clamping member includes: a second screw meshing with the clamping gear and a second clamping abutment disposed at one axial end of the second screw; wherein the first clamping abutment and the second clamping abutment are arranged in opposite directions, such that by rotating the clamping gear in different directions, the first clamping abutment and the second clamping abutment can simultaneously extend outward and retract inward.

[0010] According to some embodiments of this application, the clamping assembly further includes a clamping control disk; the clamping control disk is disposed at the bottom of the housing away from the top; the clamping control disk is torsionally connected to the clamping gear via a linkage to control the rotation of the clamping gear.

[0011] According to some embodiments of this application, the main PCB includes: a power management module, a signal processing module, a main computing unit, and a communication module.

[0012] According to the speed detection device provided in this application, the magnetic flux leakage probe is designed to be retractable, thus increasing its flexibility of use. The speed detection device also features a clamping assembly with a simple structure, easily clamped and fixed to the rotating part being detected, eliminating the need for handheld operation and ensuring a fixed measuring point, making it particularly suitable for most asynchronous motors. Furthermore, the magnetic flux leakage probe can employ a high-sensitivity Hall sensor, and the circuit design achieves a high signal-to-noise ratio, improving the usability of the magnetic field data. In summary, the speed detection device of this invention is low-cost, compact, easy to use, supports wireless communication, and has good compatibility with other condition monitoring products.

[0013] On the other hand, embodiments of this application provide a measurement method applied to a speed detection device. The speed detection device is the speed detection device described in any of the above embodiments, wherein the main PCB includes a main computing unit, and the measurement method is embedded in the main computing unit for application in the speed detection device; the measurement method includes:

[0014] The original magnetic flux leakage data is collected by the magnetic flux leakage probe.

[0015] The spectrum and KPI values ​​are obtained based on the raw leakage magnetic field data.

[0016] The rotational speed calculation method used based on KPI values ​​includes the sideband method and the rotor slot harmonic method. The sideband method searches for frequency sidebands within the frequency range of the spectrum based on the number of motor pole pairs, and obtains the rotor speed based on the bandwidth of the frequency sidebands. The rotor slot harmonic method obtains the rotor speed based on the frequencies corresponding to multiple sets of maximum amplitude values ​​in the spectrum and the number of motor pole pairs.

[0017] According to some embodiments of this application, the steps of obtaining the spectrum and KPI values ​​include:

[0018] The spectrum is obtained by performing FFT analysis and transformation on the raw magnetic flux leakage data collected by the magnetic flux leakage probe;

[0019] Based on the spectrum, obtain the maximum amplitude value in the spectrum and its corresponding maximum amplitude value frequency, as well as the second amplitude value corresponding to twice the maximum amplitude value frequency;

[0020] Compare the maximum amplitude value and the second amplitude value; when the ratio of the second amplitude value to the maximum amplitude value is less than 0.5, the KPI is 1, and the rotor speed is calculated using the rotor slot harmonic method; when the ratio of the second amplitude value to the maximum amplitude value is greater than or equal to 0.5, the KPI is 0, and the rotor speed is calculated using the sideband method.

[0021] According to some embodiments of this application, the sideband method includes:

[0022] Based on the number of motor pole pairs, search for frequency sidebands within the frequency range (0, 2*fs) of the spectrum;

[0023] Within the frequency range (0, 2*fs), obtain the left and right bands of the maximum amplitude frequency, and determine that the width of the left band and the width of the right band are equal or close.

[0024] When the width of the left strip and the width of the right strip are equal or close, the rotor speed is obtained based on the width of the left strip and the width of the right strip; when the width of the left strip and the width of the right strip are not equal and not close, it is determined that the rotor speed calculation has failed, and the process returns to the step of collecting the original leakage magnetic data by the leakage magnetic probe for calculation.

[0025] According to some embodiments of this application, the rotor slot harmonic method includes:

[0026] Limit the search scope;

[0027] Filter out the frequency of the largest amplitude and its harmonics within the search range;

[0028] Based on the amplitude, obtain the frequency values ​​corresponding to the first N peaks, where N is greater than 1;

[0029] Two frequency values ​​corresponding to the first N peaks are selected as a group for difference calculation. When the absolute value of the difference between the two selected frequency values ​​in any group is equal to or close to an integer multiple of twice the maximum amplitude frequency, the rotor speed is calculated based on the number of motor pole pairs, the larger of the two selected frequency values, and the maximum amplitude frequency. When the absolute value of the difference between the two selected frequency values ​​in all groups is not equal to and not close to an integer multiple of twice the maximum amplitude frequency, the rotor speed calculation is judged to have failed, and the process returns to the step of collecting the original leakage magnetic data by the leakage magnetic probe for calculation.

[0030] According to some embodiments of this application, the step of calculating the rotor speed based on the number of motor pole pairs, the larger of two selected frequency values, and the frequency with the largest amplitude includes:

[0031] The number of rotor slots is obtained based on the number of motor pole pairs;

[0032] The rotor speed is calculated based on the number of rotor slots and the sum of the larger of the two selected frequency values ​​and the maximum amplitude frequency.

[0033] According to the measurement method for speed detection devices provided in this application, the rotor speed can be obtained by selecting different calculation methods based on the ratio of the second amplitude to the maximum amplitude. This application combines the sideband method and the rotor slot harmonic method, which greatly expands the applicable scenarios compared to a single algorithm. It is also applicable to lightly loaded or unloaded, aluminum-cased (low leakage flux) asynchronous motors, while traditional algorithms are only applicable to some loaded, iron-cased (high leakage flux) asynchronous motors. This improves the accuracy, robustness, and applicability of its diagnostic algorithm. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 An exploded view of a rotational speed detection device according to an embodiment of this application is shown;

[0036] Figure 2 A front view of a clamping assembly according to an embodiment of this application is shown;

[0037] Figure 3 A structural block diagram of a speed detection device according to an embodiment of this application is shown; and

[0038] Figure 4 A flowchart of a measurement method according to an embodiment of this application is shown. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the described embodiments of this application are within the scope of protection of this application.

[0040] This invention provides a speed detection device and a method for measuring the speed of rotating equipment. The rotating equipment can be, but is not limited to, a motor. For example, most existing motors on the market, such as drive motors for fans and pumps, are asynchronous motors directly driven by the mains power supply. The speed detection device can perform non-invasive speed detection on these types of asynchronous motors.

[0041] Figure 1 An exploded schematic diagram of a rotational speed detection device according to an embodiment of this application is shown. In some embodiments, such as Figure 1 As shown, the rotational speed detection device includes: a housing 1; a magnetic flux leakage probe 2, which is disposed on the top side of the housing and can extend and retract relative to the housing 1; a main printed circuit board (PCB) 3, which is disposed inside the housing 1; and a flexible PCB 4, one end of which is electrically connected to the magnetic flux leakage probe 2 and the other end of which is electrically connected to the main PCB 3.

[0042] The housing has a hollow space to accommodate the main printed circuit board (PCB) 3 and the flexible PCB 4. The housing can also be designed to be wider at one end to provide sufficient space for the main printed circuit board (PCB) 3, and gradually narrow at the other end, i.e., the top. That is, the top of the housing has a relatively slender structure. The magnetic flux leakage probe 2 can be set on one side of the slender top, which is conducive to fixing the speed detection device to the rotating equipment being measured, such as fixing it to the heat dissipation fins of the motor.

[0043] In addition, a Hall sensor can be selected as the magnetic flux leakage probe 2. A Hall sensor is an electronic sensor based on the Hall effect, which can detect changes in magnetic fields and convert them into electrical signals.

[0044] The flexible PCB 4 is electrically connected between the magnetic flux leakage probe 2 and the main PCB 3. Due to the flexibility of the flexible PCB 4, it can bend and deform, which makes the magnetic flux leakage probe 2 and the flexible PCB 4 connected to it expand and contract relative to the housing 1.

[0045] Specifically, such as Figure 1As shown, the housing 1 is provided with a slide rail 11 extending along the extension direction of the magnetic flux leakage probe 2, and a slider 12 movable along the slide rail 11; the flexible PCB 4 is disposed on the slider 12, and the magnetic flux leakage probe 2 extends and retracts relative to the housing 1 by the movement of the slider 12 on the slide rail 11.

[0046] like Figure 1 As shown, the slide rail 11 can extend from the slender top of the housing 1 into the housing 1. The flexible PCB 4 is arranged along the slide rail 11 and extends out of the housing 1, and is electrically connected to the magnetic flux leakage probe 2. The slider 12 can also be connected to a telescopic push knob disposed on the outside of the housing 1. In this way, the operator can control the sliding of the flexible PCB 4 on the slide rail 11 by controlling the telescopic push knob, and further control the extension and retraction of the magnetic flux leakage probe to adjust the position of the magnetic flux leakage probe 2 and collect raw magnetic flux leakage data.

[0047] In some embodiments, the rotational speed detection device further includes a clamping assembly 5, which is disposed on the housing 1. Figure 2 A front view of a clamping assembly according to an embodiment of this application is shown. Figure 2 As shown, the clamping assembly 5 includes: a first clamping gear 51, a first clamping member 52, and a second clamping member 53.

[0048] Specifically, such as Figure 2 As shown, the first clamping member 52 includes a first screw 521 that meshes with the clamping gear 51 and a first clamping abutment portion 522 disposed at one axial end of the first screw 521; the second clamping member 53 includes a second screw 531 that meshes with the clamping gear 51 and a second clamping abutment portion 532 disposed at one axial end of the second screw 531; wherein the first clamping abutment portion 522 and the second clamping abutment portion 532 are arranged in opposite directions, so that by rotating the clamping gear 51 in different directions, the first clamping member 52 and the second clamping member 53 can simultaneously extend outward and retract inward.

[0049] It is understood that the first clamping abutment portion 522 is disposed at the axial end of the first clamping member 52 in the outward extension direction, and the second clamping abutment portion 532 is disposed at the axial end of the second clamping member 53 in the outward extension direction. When the first clamping member 52 and the second clamping member 53 extend outward simultaneously, the first clamping abutment portion 522 and the second clamping abutment portion 532 also extend outward simultaneously, and exceed the housing 1 in their respective extension directions, so that the first clamping abutment portion 522 and the second clamping abutment portion 532 can exceed the housing 1 and abut against and clamp the rotating device being detected. For example, the speed detection device can be clamped between two heat dissipation fins of the motor's heat dissipation port by the clamping assembly 5. By rotating the clamping gear 51, the first clamping abutment portion 522 and the second clamping abutment portion 532 respectively abut against the two heat dissipation fins to clamp the speed detection device.

[0050] Furthermore, to facilitate operation by the operator, the clamping assembly 5 also includes a clamping control disk 54; since the bottom of the housing 1, which is away from the top, is more convenient for the operator to control, the clamping control disk 54 can be set at the bottom of the housing 1; the clamping control disk 54 is torsionally connected to the clamping gear 51 through the connecting rod 55 to control the rotation of the clamping gear 51, thereby controlling the speed detection device to clamp onto the rotating equipment being detected, or to remove it from the rotating equipment.

[0051] Figure 3 A structural block diagram of a rotational speed detection device according to an embodiment of this application is shown. In some embodiments, such as Figure 3 As shown, the main PCB 3 includes: a power management module 301, a signal processing module 302, a main computing unit 303, and a communication module 304.

[0052] The power management module 301 provides power to other modules, including the signal processing module 302, the main computing unit 303, and the communication module 304, as well as the leakage magnetic field probe 2. The signal processing module 302 processes the raw leakage magnetic field data signal collected by the leakage magnetic field probe 2, including amplification and filtering. The main computing unit 303 incorporates a measurement method to calculate and obtain the rotor speed based on the raw leakage magnetic field data collected by the leakage magnetic field probe 2. The communication module 304 includes an LCD display and a Bluetooth / wireless extension module. The LCD display shows the calculated rotor speed value, and / or the rotor speed is sent to other status monitoring or fault diagnosis devices via the Bluetooth module.

[0053] According to the speed detection device provided in this application, the magnetic flux leakage probe is designed to be retractable, thus increasing its flexibility of use. The speed detection device also features a clamping assembly with a simple structure, easily clamped and fixed to the rotating part being detected, eliminating the need for handheld operation and ensuring a fixed measuring point, making it particularly suitable for most asynchronous motors. Furthermore, the magnetic flux leakage probe can employ a high-sensitivity Hall sensor, and the circuit design achieves a high signal-to-noise ratio, improving the usability of the magnetic field data. In summary, the speed detection device of this invention is low-cost, compact, easy to use, supports wireless communication, and has good compatibility with other condition monitoring products.

[0054] On the other hand, the present invention also provides a measurement method for a speed detection device, wherein the speed detection device is the speed detection device described in any of the above embodiments, wherein the main PCB 3 includes a main computing unit 303, and the measurement method is embedded in the main computing unit 303 for application in the speed detection device.

[0055] Figure 4 A flowchart illustrating a measurement method according to an embodiment of this application is shown. See also... Figure 4 As shown, the measurement methods include:

[0056] The original magnetic flux leakage data is collected by the magnetic flux leakage probe 2;

[0057] The spectrum and KPI values ​​are obtained based on the raw leakage magnetic field data.

[0058] The rotational speed calculation method used based on KPI values ​​includes the sideband method and the rotor slot harmonic method. The sideband method searches for frequency sidebands within the frequency range of the spectrum based on the number of motor pole pairs p, and obtains the rotor speed n based on the bandwidth of the frequency sidebands. r The rotor slot harmonic method obtains the rotor speed n based on the frequencies corresponding to the maximum amplitude values ​​of multiple sets in the spectrum and the number of motor pole pairs p. r .

[0059] Furthermore, the steps of obtaining the spectrum and KPI values ​​include:

[0060] The spectrum is obtained by performing FFT analysis and transformation on the raw leakage magnetic field data collected by the leakage magnetic field probe 2;

[0061] Based on the spectrum, obtain the maximum amplitude A1 in the spectrum and its corresponding maximum amplitude frequency fs, as well as the second amplitude A2 corresponding to twice the maximum amplitude frequency fs;

[0062] Compare the maximum amplitude A1 with the second amplitude A2; when the ratio of the second amplitude A2 to the maximum amplitude A1 is less than 0.5, the KPI is 1, and the rotor speed n is calculated using the rotor slot harmonic method. r When the ratio of the second amplitude A2 to the maximum amplitude A1 is greater than or equal to 0.5, the KPI is 0, and the rotor speed n is calculated using the sideband method. r .

[0063] The sideband method and the rotor slot harmonic method are described in detail below.

[0064] The sideband method includes:

[0065] Based on the number of motor pole pairs (p), search for frequency sidebands within the frequency range (0, 2*fs) of the spectrum;

[0066] Within the frequency range (0, 2*fs), obtain the left and right bands of the maximum amplitude frequency (fs), and determine that the width of the left band and the width of the right band are equal or close.

[0067] When the width of the left strip and the width of the right strip are equal or close, the rotor speed n is obtained according to Formula 1 based on the widths of the left strip and the right strip. r ;

[0068] Formula 1:n r = (Left bandwidth + Right bandwidth) * 60 / 2

[0069] When the widths of the left and right strips are not equal and are not close, the rotor speed n is determined to be... r If the calculation fails, return to the step of "collecting raw leakage magnetic data by the leakage magnetic probe 2" for calculation.

[0070] The term "close" means that the width of the left band and the width of the right band do not differ by more than 5‰. If the width of the left band and the width of the right band differ by more than 5‰, they are considered "not close".

[0071] The rotor slot harmonic method includes:

[0072] Limit the search range (f) min f max );

[0073] In the search range (f) min f max The maximum amplitude frequency f is filtered out within the range. s and its harmonics;

[0074] Based on the amplitude, obtain the frequency values ​​corresponding to the first N peaks, where N is greater than 1;

[0075] Select two frequency values ​​corresponding to the first N peaks as a group for difference calculation;

[0076] When the absolute value of the difference between any two selected frequency values ​​is equal to or close to twice the maximum amplitude frequency f s When the value is an integer multiple of the value, it is based on the number of motor pole pairs p, the larger of the two selected frequency values, and the maximum amplitude frequency f. s The rotor speed n is calculated according to Formula 2. r ;

[0077] Formula 2:n r =f rsh *60 / Z

[0078] When the absolute value of the difference between the two frequency values ​​selected by all groups is not equal to and does not approach twice the maximum amplitude frequency f s When the value is an integer multiple of the value, it is determined to be the rotor speed n. r If the calculation fails, return to the step of "collecting raw leakage magnetic data by the leakage magnetic probe 2" for calculation.

[0079] Here, "close" refers to the absolute value of the difference between the two selected frequency values ​​and twice the maximum amplitude frequency f. sThe difference between integer multiples of the selected two frequency values ​​does not exceed 0.5‰. If the absolute value of the difference between the two selected frequency values ​​and twice the maximum amplitude frequency f... s If the difference between integer multiples exceeds 5‰, it is considered "not close".

[0080] The step of "selecting two frequency values ​​corresponding to the first N peaks as a group for difference calculation" can be specifically described as follows:

[0081] Sort the first N peaks according to their amplitude; where N can be any number greater than 1.

[0082] The frequency values ​​corresponding to the largest peak amplitude and the second largest peak amplitude among the first N peaks are used as the first group for difference calculation; if the absolute value of the difference is equal to or close to twice the frequency of the largest amplitude f... s The rotor speed n is calculated using Formula 2 as an integer multiple of the given value. r If the absolute value of the difference is not equal to and does not approach twice the maximum amplitude frequency f s If the frequency is an integer multiple of the maximum amplitude, the next set of difference calculations continues. The frequency corresponding to the largest peak amplitude and the frequency corresponding to the third largest peak amplitude are used as the second set for difference calculation, and so on. This process continues until the absolute value of a set of differences is equal to or close to an integer multiple of twice the frequency of the maximum amplitude. At this point, the difference calculation stops, and the rotor speed n is calculated according to Formula 2. r Otherwise, if the absolute value of the difference between the two frequency values ​​selected by all groups is not equal to and does not approach twice the maximum amplitude frequency f. s When the value is an integer multiple of the value, it is determined to be the rotor speed n. r If the calculation fails, return to the step of "collecting raw leakage magnetic data by the leakage magnetic probe 2" for calculation.

[0083] It is understandable that, due to the maximum amplitude frequency f s Its harmonics have been filtered out, therefore the frequency values ​​corresponding to the first N peaks do not include the maximum amplitude frequency f. s And its harmonics.

[0084] Furthermore, the frequency value based on the number of motor pole pairs p, the larger of the two selected frequency values, and the maximum amplitude frequency f... s The rotor speed n is calculated. r The steps include:

[0085] The number of rotor slots Z is obtained based on the number of motor pole pairs p;

[0086] Based on the rotor slot number Z and the larger of the two selected frequency values ​​and the maximum amplitude frequency f s The rotor speed n is obtained by summing the values. r .

[0087] For example, if the two selected frequencies are f1 and f2, and assuming f1 > f2, then f rsh =f1+f s Therefore, f rsh Substituting into Formula 2, the rotor speed n can be calculated. r .

[0088] According to the measurement method for speed detection devices provided in this application, the rotor speed can be obtained by selecting different calculation methods based on the ratio of the second amplitude to the maximum amplitude. This application combines the sideband method and the rotor slot harmonic method, which greatly expands the applicable scenarios compared to a single algorithm. It is also applicable to lightly loaded or unloaded, aluminum-cased (low leakage flux) asynchronous motors, while traditional algorithms are only applicable to some loaded, iron-cased (high leakage flux) asynchronous motors. This improves the accuracy, robustness, and applicability of its diagnostic algorithm.

[0089] While possible embodiments have been described exemplarily in the foregoing description, it should be understood that numerous variations of embodiments exist through combinations of all known and readily conceived technical features and implementation methods. Furthermore, it should be understood that the exemplary embodiments are merely examples and do not in any way limit the scope, application, or construction of this application. The foregoing description is more intended to provide those skilled in the art with technical guidance for transforming at least one exemplary embodiment, wherein various changes can be made, particularly regarding changes to the function and structure of the components, without departing from the scope of the claims.

Claims

1. A speed detection device for rotating equipment, characterized in that, include: Shell (1); A magnetic flux leakage probe (2) is disposed on the top side of the housing and can extend and retract relative to the housing (1); The main PCB (3) is disposed within the housing (1); as well as A flexible PCB (4) is electrically connected at one end to the magnetic leakage probe (2) and at the other end to the main PCB (3).

2. The rotational speed detection device according to claim 1, wherein, The housing (1) is provided with a slide rail (11) extending along the extension direction of the magnetic flux leakage probe (2) and a slider (12) movable along the slide rail (11); the flexible PCB (4) is disposed on the slider (12), and the magnetic flux leakage probe (2) extends and retracts relative to the housing (1) by the movement of the slider (12) on the slide rail (11).

3. The rotational speed detection device according to claim 1 further includes: A clamping assembly (5) is disposed on the housing (1); The clamping assembly (5) includes: a clamping gear (51), a first clamping member (52), and a second clamping member (53); The first clamping member (52) includes: a first screw (521) meshing with the clamping gear (51) and a first clamping abutment (522) disposed at one axial end of the first screw (521); the second clamping member (53) includes: a second screw (531) meshing with the clamping gear (51) and a second clamping abutment (532) disposed at one axial end of the second screw (531); wherein the first clamping abutment (522) and the second clamping abutment (532) are arranged in opposite directions, such that by rotating the clamping gear (51) in different directions, the first clamping abutment (522) and the second clamping abutment (532) can simultaneously extend outward and retract inward.

4. The rotational speed detection device according to claim 3, wherein, The clamping assembly (5) further includes a clamping control disk (54); the clamping control disk (54) is disposed at the bottom of the housing (1) away from the top; the clamping control disk (54) is torsionally connected to the clamping gear (51) via a connecting rod (55) to control the rotation of the clamping gear (51).

5. The rotational speed detection device according to claim 1, wherein, The main PCB (3) includes: a power management module (301), a signal processing module (302), a main computing unit (303), and a communication module (304).

6. A measurement method applied to a speed detection device, characterized in that, The rotational speed detection device is the rotational speed detection device according to any one of claims 1 to 5, wherein the main PCB (3) includes a main computing unit (303), and the measurement method is embedded in the main computing unit (303) for application in the rotational speed detection device; the measurement method includes: The original magnetic flux leakage data is collected by the magnetic flux leakage probe (2); The spectrum and KPI values ​​are obtained based on the raw leakage magnetic field data. The rotational speed calculation method used is determined based on KPI values. This method includes the sideband method and the rotor slot harmonic method. Specifically, the sideband method searches for frequency sidebands within the frequency range of the spectrum based on the number of motor pole pairs (p), and obtains the rotor speed (n) based on the bandwidth of these frequency sidebands. r The rotor slot harmonic method obtains the rotor speed (n) based on the frequencies corresponding to the maximum amplitude values ​​of multiple sets in the spectrum and the number of motor pole pairs (p). r ).

7. The measurement method according to claim 6, wherein, The steps for obtaining the spectrum and KPI values ​​include: The spectrum is obtained by performing FFT analysis and transformation on the raw magnetic flux leakage data collected by the magnetic flux leakage probe (2); Based on the spectrum, obtain the maximum amplitude (A1) and its corresponding maximum amplitude frequency (f) in the spectrum. s ), and twice the maximum amplitude frequency (f s The second amplitude (A2) corresponding to point ); Compare the maximum amplitude (A1) and the second amplitude (A2); when the ratio of the second amplitude (A2) to the maximum amplitude (A1) is less than 0.5, the KPI is 1, and the rotor speed (n) is calculated using the rotor slot harmonic method. r When the ratio of the second amplitude (A2) to the maximum amplitude (A1) is greater than or equal to 0.5, the KPI is 0, and the rotor speed (n) is calculated using the sideband method. r ).

8. The measurement method according to claim 7, wherein, The sideband method includes: Based on the number of motor pole pairs (p) in the frequency range (0, 2*f) of the spectrum... s Search frequency sideband within ) In the frequency range (0, 2*f) s The maximum amplitude frequency (f) is obtained within ) s The left and right bands of the left and right bands are determined, and it is determined that the width of the left band and the width of the right band are equal or close. When the width of the left strip and the width of the right strip are equal or close, the rotor speed (n) is obtained based on the width of the left strip and the width of the right strip. r If the width of the left strip and the width of the right strip are not equal and not close, it is determined that the rotor speed calculation has failed, and the calculation is returned to the step of collecting the original leakage magnetic data by the leakage magnetic probe (2).

9. The measurement method according to claim 7, wherein, The rotor slot harmonic method includes: Limit the search range (f) min f max ); In the search range (f) min f max ) Filter out the frequency of maximum amplitude (f) s ) and its harmonics; Based on the amplitude, obtain the frequency values ​​corresponding to the first N peaks, where N is greater than 1; Two frequency values ​​corresponding to the first N peaks are selected as a group for difference calculation; when the absolute value of the difference between the two selected frequency values ​​in any group is equal to or close to twice the maximum amplitude frequency (f s When the frequency is an integer multiple of the number of motor pole pairs (p), then based on the larger of the two selected frequency values ​​and the maximum amplitude frequency (f)... s The rotor speed (n) is calculated to obtain the rotor speed. r When the absolute value of the difference between the two frequency values ​​selected by all groups is not equal to and does not approach twice the maximum amplitude frequency (f s If the value is an integer multiple of ), then the rotor speed calculation is considered to have failed, and the process returns to the step of collecting the original leakage magnetic data by the leakage magnetic probe (2) for calculation.

10. The measurement method according to claim 9, wherein, The frequency value is based on the number of pole pairs (p) of the motor, the larger of the two selected frequency values, and the maximum amplitude frequency (f). s The rotor speed (n) is calculated to obtain the rotor speed. r The steps include: The number of rotor slots (Z) is obtained based on the number of motor pole pairs (p); Based on the number of rotor slots (Z) and the larger of the two selected frequency values ​​and the maximum amplitude frequency (f) s The rotor speed (n) is obtained by summing the values ​​of n and n. r ).

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