A frequency amplification device and a portable low-frequency vibration detector

Abstract

The present invention relates to vibration detection, and particularly to a frequency amplification device and a portable low-frequency vibration detector, comprising: a swinging member, a first input end for sensing mechanical vibrations generated by a vibration source, and a first output end for outputting a swinging motion having the same frequency as the vibration source; an inductor coil disposed on the first output end of the swinging member, the inductor coil having N turns that are independent of each other, and the first output end being located between the positive and negative poles of a magnetic field; when the swinging member swings for one period, at least M turns of the inductor coil can successively cut the magnetic induction lines generated by a magnetic field source twice, and each time of cutting generates a current segment; N≥M≥2, and N and M are both natural numbers; a first energy conversion device, the first energy rotation shaft device is electrically connected to both ends of the inductor coil, and the output end of the first energy conversion device converts the received multiple current segments into mechanical vibrations of the same number of times, so as to improve the detection accuracy and efficiency of low-frequency vibrations.

Description

Technical Field

[0001] The present invention relates to vibration detection, and in particular to a frequency amplification device and a portable low-frequency vibration detector. Background Art

[0002] Air conditioner units often face after-sales complaints about vibration and noise. When technicians handle noise problems on-site, they can only distinguish the quality of the sound and the relative magnitude of the noise by ear. However, due to the lack of professional equipment, they are unable to identify the operating frequency of the unit with noise problems, thus unable to provide an effective solution to the problem. To obtain the operating frequency information of the unit, it is necessary to carry a computer and related testing equipment. Professional equipment is cumbersome and complex to operate, requires a lot of auxiliary accessories and is not convenient to carry (such as sensors, glue, etc.). Especially for the detection of low-frequency vibration, the error is relatively large.

[0003] In view of the above problems, no effective solution has been proposed yet. Summary of the Invention

[0004] To improve the detection accuracy, efficiency and convenience of low-frequency vibration, the present invention provides a frequency amplification device and a portable low-frequency vibration detector.

[0005] On the one hand, a frequency amplification device includes:

[0006] A support frame;

[0007] A swinging member, the swinging member is hinged to the support frame, one end is a first input end, and the other end is a first output end; the first input end is used to sense the mechanical vibration generated by the vibration source, and the first output end is used to output a swinging motion with the same frequency as the vibration source;

[0008] An inductor coil is arranged on the first output end of the swinging member. The inductor coil has N independent turns, and the N turns of the inductor coil are arranged in sequence along the swinging direction of the first output end;

[0009] A magnetic field source is used to generate a magnetic field, and the first output end is located between the positive and negative poles of the magnetic field; the magnetic field source is designed such that when the swinging member swings relative to the support frame, the inductor coil can cut the magnetic induction lines generated by the magnetic field source; when the swinging member swings one cycle, at least M turns of the inductor coil can successively cut the magnetic induction lines generated by the magnetic field source twice, and each cut generates a current segment; N≥M≥2, and N and M are both natural numbers;

[0010] A first energy conversion device, the first energy conversion shaft device is electrically connected to both ends of the inductor coil, and the output end of the first energy conversion device converts the received multiple current segments into mechanical vibrations of the same number of times.

[0011] Preferably, a plate - like body is formed at the first output end of the swing member.

[0012] Preferably, the inductance coils are radially distributed around the hinge axis of the swing member at the first output end.

[0013] Preferably, the first output end forms a sector - like body, and N turns of the inductance coils are evenly wound on the outer arc of the sector - like body. Preferably, the N turns of the inductance coils are symmetrically distributed relative to the center line of the sector - like body.

[0014] Preferably, the magnetic field source includes a first magnet and a second magnet which are oppositely arranged, and the first output end of the swing member is swingably arranged between the first magnet and the second magnet so as to be able to cut the magnetic induction lines between the first magnet and the second magnet.

[0015] On the other hand, the present invention also provides a portable low - frequency vibration detector, including the frequency amplification device; a mechanical amplitude amplification mechanism, which includes a second input end and a second output end, wherein the second input end is used to sense the vibration of the vibration source, and the second output end is used to be connected to the first input end of the swing member to output a co - frequency mechanical vibration with an increased amplitude to the first input end.

[0016] Preferably, the mechanical amplitude amplification mechanism includes a second energy conversion device, a second charge amplifier and a third energy conversion device which are connected in sequence;

[0017] The second energy conversion device is used to sense the mechanical vibration generated by the vibration source and convert the sensed mechanical vibration into a co - frequency first alternating - current charge. One end of the second energy conversion device is used as the second input end to sense the vibration of the vibration source, and the other end is used as an output end and is electrically connected to the input end of the second charge amplifier;

[0018] The second charge amplifier is used to receive the first alternating - current charge output by the second energy conversion device, amplify the first alternating - current charge into a second alternating - current charge and then output it to the third energy conversion device;

[0019] The third energy conversion device is used to receive the second alternating - current charge, convert the second alternating - current charge into a co - frequency mechanical vibration, and transmit the mechanical vibration to the first input end of the swing member.

[0020] Preferably, a detection rod is provided at the second input end of the mechanical amplitude amplification mechanism. One end of the detection rod is connected to the second energy converter, and the other end is used to sense the mechanical vibration generated by the vibration source and transmit the sensed mechanical vibration to the second energy conversion device; a transmission rod is provided at the second output end of the mechanical amplitude amplification mechanism. One end of the transmission rod is connected to the third energy converter, and the other end is connected to the first input end of the swinging member. The transmission rod transmits the mechanical vibration output by the third energy conversion device to the first input end of the swinging member at the same frequency.

[0021] Preferably, a chute is provided at the first input end. One end of the transmission rod is provided with a sliding portion, and the sliding portion is located in the chute and can slide in the chute.

[0022] Preferably, the portable low-frequency vibration detector further includes a frequency resonance device. The first energy conversion device is coupled with the frequency resonance device to generate resonance at the same frequency as the mechanical vibration output by the first energy conversion device.

[0023] Preferably, the first energy conversion device and the inductor coil are connected through a first charge amplifier; the first charge amplifier is used to receive multiple current segments output by the inductor coil, and amplify the current of the received multiple current segments and then output it to the first energy conversion device.

[0024] Preferably, the frequency resonance device includes a varactor resonator. The varactor resonator forms a resonance cavity. The resonance cavity includes a first port and a second port arranged oppositely. The first energy conversion device is located in the resonance cavity, and the first energy conversion device is electrically connected to the first charge amplifier through the first port;

[0025] A piston is provided in the resonance cavity. One end of the piston is connected to a piston rod. The piston rod passes through the second port and extends to the outside of the resonance cavity to be connected to a driving member. A variable-volume cavity is formed between the first energy conversion device and the piston. By controlling the movement of the piston, the volume of the cavity can be adjusted, so that the varactor resonator generates vibration at the same frequency as the mechanical vibration output by the first energy conversion device.

[0026] Preferably, the first energy conversion device is a first piezoelectric film, the second energy conversion device is a second piezoelectric film, and the third energy conversion device is a third piezoelectric film.

[0027] In the present invention, the first input end of the swing member vibrates at the same frequency as the vibration source, and a multi-turn inductance coil is arranged at the first output end. In one vibration cycle, within a certain angle of reciprocating rotation of the swing member, the M-turn inductance coil at the first output end cuts the magnetic induction line twice in sequence, generating 2M electrical signals. The 2M electrical signals are converted into 2M vibrations through the first piezoelectric film. In a complete vibration cycle, the first piezoelectric film generates 2M vibrations, so that the vibration frequency of the vibration source is increased to 2M times that of the vibration source. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the frequency amplification device according to an embodiment of the present invention;

[0029] Figure 2 It is a schematic diagram of the portable low-frequency vibration detector according to an embodiment of the present invention.

[0030] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0031] In the drawings: 1 - swing member; 101 - first input end; 102 - first output end; 201 - first piezoelectric film; 3 - inductance coil; 401 - first magnet; 402 - second magnet; 501 - transmission rod; 502 - detection rod; 103 - chute; 6 - varactor resonator; 7 - housing; 701 - first charge amplifier; 702 - second charge amplifier; 202 - second piezoelectric film; 203 - third piezoelectric film; 8 - piston. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above drawings are used to distinguish similar objects and do not have to be used to describe a specific order or sequence; "front end" and "rear end" are relative. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0034] The present invention relates to vibration detection, and particularly to a frequency amplification device and a portable low-frequency vibration detector. Air-conditioning units often face after-sales complaints about vibration and noise. When technicians handle noise problems on-site, they can only distinguish the quality of the sound and the relative magnitude of the noise by ear. However, due to the lack of professional equipment, they are unable to identify the operating frequency of the unit with noise problems, thus unable to provide an effective solution to the problem. To obtain the operating frequency information of the unit, it is necessary to carry a computer and relevant testing equipment. Professional equipment is cumbersome and complex to operate, requires a lot of auxiliary accessories and is not convenient to carry (such as sensors, glue, etc.). Especially for the detection of low-frequency vibration, the error is relatively large.

[0035] In view of the above problems, the present invention provides a frequency amplification device and a portable low-frequency vibration detector.

[0036] On the one hand, as Figure 1-2As shown, a frequency amplification device includes: a support frame; a swinging member 1, the swinging member 1 is hinged to the support frame, one end is the first input end 101, and the other end is the first output end 102; the first input end 101 is used to sense the mechanical vibration generated by the vibration source, and the first output end 102 is used to output a swinging motion with the same frequency as the vibration source; an inductor coil 3 is arranged on the first output end 102 of the swinging member 1, the inductor coil 3 has N independent turns, and the N turns of inductor coils 3 are arranged in sequence along the swinging direction of the first output end 102; a magnetic field source, the magnetic field source is used to generate a magnetic field, and the first output end 102 is located between the positive and negative poles of the magnetic field; the magnetic field source is designed such that when the swinging member 1 swings relative to the support frame, the inductor coil 3 can cut the magnetic induction lines generated by the magnetic field source; when the swinging member 1 swings one cycle, at least M turns of inductor coils 3 can successively cut the magnetic induction lines generated by the magnetic field source twice, and each cut generates a current segment; N≥M≥2, and N and M are both natural numbers; a first energy conversion device, the first energy rotation shaft device is electrically connected to both ends of the inductor coil 3, and the output end of the first energy conversion device converts the received multiple current segments into the same number of mechanical vibrations. When the first input end 101 is vibrated, the swinging member 1 rotates around the rotating shaft, and the first output end 102 of the swinging member 1 swings. In one swinging cycle, at least M of the N independent inductor coils 3 cut the magnetic induction lines generated by the magnetic field source; the greater the amplitude of the vibration source, the greater the swinging amplitude of the first output end 102; considering the actual vibration situation, for a specific structure, the lower the vibration frequency, the greater the corresponding amplitude; when the vibration frequency of the vibration source is low, its amplitude is large, the swinging amplitude of the first output end 102 increases, and the more inductor coils 3 that cut the magnetic induction lines generated by the magnetic field source. In the one-way swing of one swinging cycle, the number of inductor coils 3 that cut the magnetic induction lines is M, and in one cycle of swinging, the number of times the inductor coils 3 cut the magnetic induction lines is 2M. That is, in one cycle of vibration of the vibration source, the number of times of cutting the magnetic induction lines is 2M, the number of electrical signal times received by the first piezoelectric film 201 is 2M, and the first piezoelectric film 201 generates 2M vibrations accordingly; thus, the vibration frequency of the vibration source is increased to 2M times. In practical applications, considering the resistance of the inductor coil 3, when the magnetic field strength is weak, the current generated by the inductor coil 3 is small, and the vibration generated on the first piezoelectric film 201 is also small. In the design, through the arrangement of the current, only the current generated when cutting the strongest magnetic field in the magnetic induction lines can act on the first piezoelectric film 201 to make the first piezoelectric film 201 generate corresponding mechanical vibrations; even if the inductor coils 3 are arranged densely and multiple independent inductor coils 3 cut the magnetic induction lines generated by the same magnetic field source at the same time, the first piezoelectric film 201 only senses the current generated when the inductor coil 3 cuts to the strongest magnetic field intensity. The value of M can be obtained by dividing the swinging amplitude of the first output end 102 by the arrangement density of the inductor coil 3.

[0037] Preferably, as Figure 1 shown, the first output end 102 of the swing member 1 forms a plate-like body; the inductor coil 3 is wound radially around the axis of the rotating shaft with the axis of the rotating shaft as the center; the end of the first output end 102 includes a circular arc surface, and the center line of the circular arc surface coincides with the axis of the rotating shaft; N turns of the inductor coil 3 are evenly distributed in the circumferential direction of the circular arc surface; N turns of the inductor coil 3 are symmetrically distributed relative to the center line of the fan-shaped body; the inductor coil 3 being radially arranged enables the part of the inductor coil 3 that cuts the magnetic induction line to be perpendicular to the magnetic induction line, and a larger induced current can be generated; when the evenly distributed multi-turn inductor coil 3 cuts the magnetic induction line, it can cut evenly, and the generated current intervals are relatively uniform. When the uniformly spaced current is transmitted to the first piezoelectric film 201, a more stable vibration can be generated. In another way, the inductor coil 3 can be wound on one side of the swing direction of the first output end 102, and the first magnet 401 and the second magnet 402 are arranged on the opposite side; when the swing member 1 does not start to swing, the inductor coil 3 cannot cut the magnetic induction line, and when the swing member 1 starts to swing, the inductor coil 3 starts to cut the magnetic induction line.

[0038] Preferably, as Figure 1 shown, the magnetic field source includes a first magnet 401 and a second magnet 402. The first magnet 401 and the second magnet 402 are respectively arranged on both sides of the swing direction of the first output end 102. The side of the first magnet 401 facing the second magnet 402 is the positive pole, and the side of the second magnet 402 facing the first magnet 401 is the negative pole; the N-turn inductor coil 3 can cut the magnetic induction line between the first magnet 401 and the second magnet 402 when swinging; a magnetic field is generated by the first magnet 401 and the second magnet 402, and the middle part of the magnetic field has the strongest magnetic field intensity, which is beneficial to different inductor coils 3 generating different current bands when cutting the magnetic induction line, and is beneficial to making the first piezoelectric film 201 generate a stable vibration.

[0039] On the other hand, as Figure 2 shown, the present invention also provides a portable low-frequency vibration detector, including a frequency amplification device.

[0040] Preferably, the portable low-frequency vibration detector includes: a frequency amplification device; a detection device disposed on a support frame, the detection device being connected to a first input end 101. When the detection device detects the vibration of a vibration source, the detection device can drive the first input end 101 to swing at the same frequency as the vibration source; a frequency resonance device fixed on the support frame, a first piezoelectric film 201 disposed in a resonance cavity of the frequency resonance device, and the vibration of the first piezoelectric film 201 can cause the frequency resonance device to resonate. By detecting the vibration source with the detection device, the vibration generated by the vibration source is transmitted to the first input end 101 through the detection device, and then the first input end 101 generates vibration at the same frequency as the vibration source. Under the action of the vibration generated at the first input end 101, the first piezoelectric film 201 generates vibration with an amplified frequency. The vibration with the amplified frequency generates resonance in the resonance cavity. By referring to the natural frequency of the resonance device corresponding to the resonance cavity, the vibration frequency of the vibration source can be obtained by dividing the fixed frequency of the resonance cavity by 2M.

[0041] Preferably, as Figure 2 shown, a detection rod 502 is provided at a second input end of the mechanical amplitude amplification mechanism. One end of the detection rod 502 is connected to a second energy converter, and the other end is used to sense the mechanical vibration generated by the vibration source and transmit the sensed mechanical vibration to the second energy conversion device; a transmission rod 501 is provided at a second output end of the mechanical amplitude amplification mechanism. One end of the transmission rod 501 is connected to a third energy converter, and the other end is connected to the first input end 101 of the swing member 1. The transmission rod 501 transmits the mechanical vibration output by the third energy conversion device to the first input end 101 of the swing member 1 at the same frequency.

[0042] Preferably, a chute 103 is formed at the first input end 101, and a sliding portion is provided at one end of the transmission rod 501. The sliding portion is located in the chute 103 and can slide in the chute 103.

[0043] Preferably, the portable low-frequency vibration detector further includes a frequency resonance device. The first energy conversion device is coupled with the frequency resonance device to generate resonance at the same frequency as the mechanical vibration output by the first energy conversion device.

[0044] Preferably, the first energy conversion device is connected to an inductor coil 3 through a first charge amplifier 701; the first charge amplifier 701 is configured to receive a plurality of current segments output by the inductor coil 3 and amplify the current of the received plurality of current segments and then output the amplified current to the first energy conversion device.

[0045] Preferably, the frequency resonance device includes a varactor resonator 6. The varactor resonator 6 includes a resonance cavity. One end of the first piezoelectric film 201 is located inside the resonance cavity. A piston 8 is provided at the other end of the resonance cavity. The piston 8 can slide inside the resonance cavity to change the resonance frequency of the resonance cavity. When the first piezoelectric film 201 vibrates, the volume of the resonance cavity is changed by the piston 8, thereby changing the natural vibration frequency of the varactor resonator 6. When the vibration generated by the varactor resonator 6 reaches the maximum, dividing the fixed vibration frequency of the varactor resonator 6 by 2M at this time can obtain the vibration frequency of the vibration source. For the same varactor resonator 6, the natural frequencies corresponding to different volumes are certain. Marks can be made at the positions corresponding to the piston 8 to mark the fixed frequencies corresponding to the varactor resonator 6 corresponding to the piston 8. When the position of the piston 8 inside the resonance cavity is changed, the natural frequency when the varactor resonator 6 resonates can be clearly read.

[0046] Preferably, a first charge amplifier 701 is provided between the inductor coil 3 and the first piezoelectric film 201 to increase the magnitude of the current, increase the mechanical amplitude output by the first piezoelectric film 201, and make it easier to identify the moment when the varactor resonator 6 resonates during the process of changing the position of the piston 8, and thus obtain the natural frequency of the varactor resonator 6 more quickly and accurately.

[0047] Preferably, as Figure 2 shown, the maximum rotation radius of the sliding groove 103 is smaller than the minimum radius of the part of the inductor coil 3 that cuts the magnetic induction line. For a vibration source with a small amplitude, after being transmitted by the swinging member 1, the swinging amplitude of the first output end 102 is greater than that of the first input end 101. The number of turns of the inductor coil 3 that the first output end 102 can cut the magnetic induction line increases. During one vibration cycle of the vibration source, the current received by the first piezoelectric film 201 increases at this time, and the mechanical vibration frequency output by the first piezoelectric film 201 increases accordingly, which is beneficial to increasing the detection range of the low-frequency vibration detector.

[0048] The detection device further includes a detection rod 502. The detection rod 502 is arranged on the support frame and can slide in its own axial direction. A second piezoelectric film 202, a second charge amplifier 702, and a third piezoelectric film 203 are sequentially connected between the first end of the detection rod 502 and the second end of the conduction rod. When the detection rod 502 detects vibration, the mechanical vibration is first converted into the frequency of the current by the second piezoelectric film 202, and then passes through the second charge amplifier 702 to increase the current intensity. After the current intensity increases, the amplitude of the mechanical vibration generated by the third piezoelectric film 203 increases, thereby increasing the vibration amplitude of the conduction rod, increasing the number of turns of the inductor wire that the first output end 102 cuts the magnetic induction line, increasing the amplification factor of the vibration frequency, and being beneficial to improving the detection of the low-frequency vibration source and expanding the detection range of the low-frequency vibration detector.

[0049] Taking the detection of the vibration of the outer casing 7 of an air conditioner by a portable low-frequency vibration detector as an example, the specific implementation process of the present invention will be introduced.

[0050] Hold the portable low-frequency vibration detector, and press the second end of the detection rod 502 against the outer casing 7, and the axial direction of the detection rod 502 is basically the same as the vibration direction of the casing 7. The detection rod 502 abuts against the casing 7 and pushes the swing member 1 to rotate forward and is stretched; within a vibration period of the detection rod 502 and the casing 7 generating the same-frequency vibration: the vibration of the casing 7 causes the detection rod 502 to vibrate at the same frequency in its own axial direction. The detection rod 502 drives one side of the second piezoelectric film 202 to vibrate at the same frequency. The second piezoelectric film 202 converts the same-frequency mechanical vibration into the same-frequency alternating current charge. The same-frequency alternating current charge is amplified by the second charge amplifier 702, and the frequency of the alternating current charge remains unchanged while the current increases; the same-frequency and increased alternating current charge is transmitted to the third piezoelectric film 203. The third piezoelectric film 203 is excited by a larger same-frequency current and generates a larger same-frequency mechanical vibration. That is to say, after the mechanical vibration of the casing 7 passes through the second piezoelectric film 202, the second charge amplifier 702 and the third piezoelectric film 203, the amplitude of the mechanical vibration is increased. The mechanical vibration drives the conduction rod to vibrate at the same frequency in its own axial direction. Due to the increase in the amplitude of the mechanical vibration, the distance that the conduction rod drives the sliding rod to slide in the chute 103 during a one-way movement within a vibration period increases, so that the swing amplitude of the first input end 101 increases, and the swing amplitude of the first output end 102 increases correspondingly. Superimposing the lever principle, the swing amplitude of the first output end 102 increases even more; the swing of the first output end 102 drives the M-turn inductor coil 3 to cut the magnetic induction lines between the first magnet 401 and the second magnet 402. Within a vibration period, in the M-turn inductor coil 3, each turn of the inductor coil 3 cuts twice, and the M-turn inductor coil 3 generates a total of 2M times of current. The 2M times of current are transmitted to the first charge amplifier 701 to increase the current and then transmitted to the first piezoelectric film 201. The first piezoelectric film 201 converts the 2M times of current into 2M times of mechanical vibration. That is to say, one vibration period of the casing 7 is converted into 2M times of mechanical vibration of the first piezoelectric film 201, and the vibration frequency is increased; change the position of the piston 8 in the resonant cavity, and then adjust the natural vibration frequency of the resonant cavity. When the resonant cavity resonates with the mechanical vibration generated by the first piezoelectric film 201, check the natural frequency value of the resonant cavity corresponding to the piston 8, and divide the natural frequency value of the resonant cavity at this time by 2M to obtain the vibration frequency of the casing 7.

[0051] The above specifically shows and describes the exemplary embodiments of the present disclosure. It should be understood that the present disclosure is not limited to the detailed structures, settings or implementation manners described here; on the contrary, the present disclosure is intended to cover various modifications and equivalent settings included within the spirit and scope of the appended claims.

Claims

1. A frequency amplification device, characterized in that, it comprises: a support frame; a swinging member, the swinging member is hinged on the support frame, one end is a first input end, and the other end is a first output end; the first input end is used to sense the mechanical vibration generated by the vibration source, and the first output end is used to output a swinging motion with the same frequency as the vibration source; an inductor coil, arranged on the first output end of the swinging member, the inductor coil has N independent turns, and the N turns of the inductor coil are arranged in sequence along the swinging direction of the first output end; a magnetic field source, the magnetic field source is used to generate a magnetic field, and the first output end is located between the positive and negative poles of the magnetic field; the magnetic field source is designed such that when the swinging member swings relative to the support frame, the inductor coil can cut the magnetic induction lines generated by the magnetic field source; when the swinging member swings one cycle, at least M turns of the inductor coil can successively cut the magnetic induction lines generated by the magnetic field source twice, and each cut generates a current segment; N≥M≥2, N and M are both natural numbers; a first energy conversion device, the first energy conversion device is electrically connected to both ends of the inductor coil, and the output end of the first energy conversion device converts the received multiple current segments into mechanical vibrations of the same number of times.

2. The frequency amplification device according to claim 1, characterized in that, the first output end of the swinging member forms a plate-like body.

3. The frequency amplification device according to claim 2, characterized in that, the inductor coil is radially distributed on the first output end with the hinge axis of the swinging member as the center.

4. The frequency amplification device according to claim 2, characterized in that, the first output end forms a sector body, and the N turns of the inductor coil are evenly wound on the sector body along the outer arc of the sector.

5. The frequency amplification device according to any one of claims 2-4, characterized in that, the magnetic field source includes a first magnet and a second magnet arranged oppositely, and the first output end of the swinging member is swingably arranged between the first magnet and the second magnet to be able to cut the magnetic induction lines between the first magnet and the second magnet.

6. A portable low-frequency vibration detector, characterized in that, it comprises the frequency amplification device according to any one of claims 1-5.

7. The portable low-frequency vibration detector according to claim 6, characterized in that, it comprises: a mechanical amplitude amplification mechanism, which includes a second input end and a second output end, wherein the second input end is used to sense the vibration of the vibration source, and the second output end is used to be connected to the first input end of the swinging member to output a co-frequency mechanical vibration with an increased amplitude to the first input end.

8. The portable low-frequency vibration detector according to claim 7, characterized in that, the mechanical amplitude amplification mechanism includes a second energy conversion device, a second charge amplifier and a third energy conversion device connected in sequence; The second energy conversion device is configured to sense the mechanical vibration generated by the vibration source and convert the sensed mechanical vibration into first AC charges of the same frequency. One end of the second energy conversion device serves as the second input end for sensing the vibration of the vibration source, and the other end serves as the output end and is electrically connected to the input end of the second charge amplifier; The second charge amplifier is configured to receive the first AC charges output by the second energy conversion device, amplify the first AC charges into second AC charges, and then output the second AC charges to the third energy conversion device; The third energy conversion device is configured to receive the second AC charges, convert the second AC charges into mechanical vibrations of the same frequency, and transfer the mechanical vibrations to the first input end of the swinging member.

9. The portable low-frequency vibration detector according to claim 8, wherein, A detection rod is provided at the second input end of the mechanical amplitude amplification mechanism. One end of the detection rod is connected to the second energy conversion device, and the other end is configured to sense the mechanical vibration generated by the vibration source and transfer the sensed mechanical vibration to the second energy conversion device; A transmission rod is provided at the second output end of the mechanical amplitude amplification mechanism. One end of the transmission rod is connected to the third energy conversion device, and the other end is connected to the first input end of the swinging member. The transmission rod transmits the mechanical vibration output by the third energy conversion device to the first input end of the swinging member at the same frequency.

10. The portable low-frequency vibration detector according to claim 9, wherein, A sliding groove is provided at the first input end. A sliding portion is provided at one end of the transmission rod, and the sliding portion is located in the sliding groove and can slide in the sliding groove.

11. The portable low-frequency vibration detector according to any one of claims 8-9, wherein, The portable low-frequency vibration detector further includes a frequency resonance device. The first energy conversion device is coupled with the frequency resonance device to generate resonance of the same frequency as the mechanical vibration output by the first energy conversion device.

12. The portable low-frequency vibration detector according to claim 11, wherein, The first energy conversion device and the inductor coil are connected via a first charge amplifier. The first charge amplifier is configured to receive multiple current segments output by the inductor coil, amplify the current of the received multiple current segments, and then output the amplified current to the first energy conversion device.

13. The portable low-frequency vibration detector according to claim 12, wherein, The frequency resonance device includes a varactor resonator. The varactor resonator forms a resonance cavity. The resonance cavity includes a first port and a second port arranged oppositely. The first energy conversion device is located in the resonance cavity, and the first energy conversion device is electrically connected to the first charge amplifier through the first port; A piston is disposed in the resonant cavity. One end of the piston is connected to a piston rod. The piston rod extends outside the resonant cavity through the second port and is connected to a driving member. A variable-volume cavity is formed between the first energy conversion device and the piston. By controlling the movement of the piston, the volume of the cavity can be adjusted, so that the varactor resonator generates vibrations with the same frequency as the mechanical vibrations output by the first energy conversion device.

14. The portable low-frequency vibration detector according to claim 13, wherein, the first energy conversion device is a first piezoelectric film, the second energy conversion device is a second piezoelectric film, and the third energy conversion device is a third piezoelectric film.

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