WO2013104188A1 - 基于位移反馈型振动台的次声发生装置 - Google Patents

基于位移反馈型振动台的次声发生装置 Download PDF

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Publication number
WO2013104188A1
WO2013104188A1 PCT/CN2012/080210 CN2012080210W WO2013104188A1 WO 2013104188 A1 WO2013104188 A1 WO 2013104188A1 CN 2012080210 W CN2012080210 W CN 2012080210W WO 2013104188 A1 WO2013104188 A1 WO 2013104188A1
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WO
WIPO (PCT)
Prior art keywords
infrasound
sensor
displacement
piston
cavity
Prior art date
Application number
PCT/CN2012/080210
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English (en)
French (fr)
Inventor
何闻
何龙标
王春宇
周远来
贾叔仕
Original Assignee
浙江大学
中国计量科学研究院
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Application filed by 浙江大学, 中国计量科学研究院 filed Critical 浙江大学
Priority to US14/130,892 priority Critical patent/US9539616B2/en
Publication of WO2013104188A1 publication Critical patent/WO2013104188A1/zh

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/10—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of mechanical energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/0207—Driving circuits
    • B06B1/0223—Driving circuits for generating signals continuous in time
    • B06B1/0238—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave
    • B06B1/0246—Driving circuits for generating signals continuous in time of a single frequency, e.g. a sine-wave with a feedback signal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
    • G01H3/005—Testing or calibrating of detectors covered by the subgroups of G01H3/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
    • B06B2201/40—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups with testing, calibrating, safety devices, built-in protection, construction details

Definitions

  • the present invention relates to an infrasound generating device, and more particularly to an infrasound generating device for generating a standard infrasound sound pressure signal for calibrating an infrasound sensor.
  • Infrasound waves are widely found in nature and human production, such as volcanic eruptions, earthquakes, nuclear explosions, rocket launches, and supersonic aircraft flights.
  • infrasound detection has attracted more and more attention in the fields of environmental protection and military surveillance.
  • infrasound waves have the characteristics of long transmission distance, strong penetrating ability, and low visibility, infrasonic technology in military and medical fields. Applications in the fields of industrial production are also becoming more widespread.
  • Infrasound sensors are critical for the detection and application of infrasound waves.
  • the performance indicators such as the sensitivity of the infrasound sensor must be calibrated before leaving the factory or after using for a period of time.
  • the infrasound sensor calibration system is an important guarantee for the development of infrasound sensor technology. It generates a standard infrasound pressure signal through the infrasound generating device, and calibrates the infrasound sensor by "absolute method” or "relative method”.
  • the infrasound generating device is an important part of the infrasound sensor calibration system, and the quality of the infrasound sound pressure signal produced directly determines the calibration accuracy of the infrasound sensor.
  • the secondary acoustic generating devices at home and abroad are driven by the motor or the vibrating table to directly generate the sinusoidal infrasound sound pressure.
  • the resulting infrasound sound pressure waveform distortion is large, thus affecting the time. Calibration accuracy of the acoustic sensor.
  • the present invention provides a subsonic based on a displacement feedback type vibrating table with small waveform distortion and guaranteed calibration accuracy of the infrasound sensor. Health device.
  • An infrasound generating device based on a displacement feedback type vibrating table comprising a displacement feedback type vibrating table system, an infrasound generating chamber and a laser vibrating measuring instrument for measuring the vibration displacement of the vibrating table, and calculating the vibration displacement obtained by the laser vibrometer to obtain an infrasound occurrence
  • the standard sound pressure value produced by the cavity
  • the displacement feedback type shaking table system comprises a signal generator, a power amplifier, a vibration table and a displacement feedback component;
  • the displacement feedback component comprises a displacement sensor for measuring a displacement waveform of the moving part of the vibration table, comparing the displacement waveform with a standard signal generated by the signal generator a comparator for deviation and a controller for calculating the deviation signal, and a signal conditioning circuit for conditioning the displacement waveform between the displacement sensor and the comparator;
  • the displacement waveform obtained by the displacement sensor is processed by the signal conditioning circuit, and the comparator is The standard signal generated by the signal generator is subtracted to obtain the deviation signal.
  • the input power amplifier is driven to drive the vibration table to perform the correcting motion, thereby realizing the vibration station output displacement and accurately tracking the low distortion signal source waveform, thereby reducing the signal source waveform.
  • the vibration table outputs the distortion of the displacement waveform, thereby reducing the distortion of the sound pressure signal output by the infrasound generating device.
  • the vibrating table is provided with an optical passage that allows the measuring light of the laser vibrometer to pass through and a reflector that reflects the measuring light back to the laser vibrometer, and the measuring light is incident from the tail of the vibrating table, and the reflector is fixed to the back of the moving part of the vibrating table;
  • the infrasound generating chamber is a closed cavity, and the infrasound generating chamber is provided with a piston adapted to the cavity, the piston is fixedly connected with the front surface of the moving part of the vibrating table, and the calibrated infrasound sensor is installed in the cavity of the infrasound generating chamber .
  • the basic principle of the infrasound generating device is that in a closed cavity whose size is much smaller than the wavelength of the acoustic wave in the medium (the maximum size is 1/20 of the wavelength), the pressure wave is excited in the closed cavity by the movement of the piston, according to the law of adiabatic gas,
  • the standard sound pressure value in the closed cavity can be obtained by substituting into the above formula, thereby realizing the absolute calibration of the infrasound microphone.
  • the displacement feedback type vibrating table can output a vibration displacement with a low distortion, according to the above formula, a sound pressure signal having a low distortion can be generated in the infrasound generating chamber.
  • the standard sound pressure value obtained by Formula 1 is used as a calibration reference of the calibrated infrasound sensor; or the infrasound generating chamber is further provided with a standard infrasound sensor, and the output of the standard infrasound sensor is used as the calibrated infrasound sensor Calibration basis.
  • the infrasound generating chamber comprises a cavity, a piston adapted to the cavity, a piston end sealing device, a sensor mounting sealing cover and a support for the holding cavity.
  • the sensor mounting sealing cover is provided with a receiving hole for accommodating the calibrated infrasound sensor, and a sensor sealing sleeve is disposed between the receiving hole and the calibrated infrasound sensor. If a standard infrasound sensor is further disposed in the cavity, the sensor mounting sealing cover is further provided with a receiving hole for accommodating a standard infrasound sensor, and a sensor sealing sleeve is disposed between the receiving hole and the standard infrasound sensor.
  • the piston end sealing device comprises an integrated sealing film and an annular sealing member for fixing the integrated sealing film on the infrasound generating chamber
  • the annular sealing member comprises a fixing member fixed to the infrasound generating chamber by screws and integrally sealed
  • the membrane is pressed against the annular pressure plate on the fixing member
  • the integrated sealing film comprises an outer ring fixed to the annular sealing member, an inner ring fixed to the piston, and a rubber film connecting the outer ring and the inner ring
  • the fixing member is provided with the outer portion
  • the first mounting groove of the ring is fitted with a second mounting groove adapted to the inner ring.
  • the integrated sealing membrane seals the piston and the cavity to form a completely sealed method.
  • the piston end seal device does not have an integral sealing film, and only the piston sleeve tightly mounted on the cavity body is sealed by the fitting gap between the piston and the piston sleeve, forming a gap sealing manner.
  • the infrasound generating device further comprises a laser vibrometer base on which the laser vibrometer is mounted, a vibrating table base on which the vibrating table is mounted, a cavity mounting bottom plate in which the infrasound generating chamber is installed, and a measuring instrument and other tools are placed.
  • the working surface, the cavity mounting bottom plate and the working surface are all mounted on the air chamber base; the laser vibrometer is placed on the base of the laser vibrometer through the adjustable bottom leg thereof, and the laser vibrometer base is placed on the foundation through the shock absorber
  • the vibrating table base and the air chamber base are mounted on the foundation by adjustable horns. Measuring instruments and other tools are measuring tools or aids that need to be used during the measurement process.
  • the technical idea of the present invention is: using a vibration table with a displacement feedback component to drive a piston to perform a sinusoidal vibration with low displacement distortion in a closed infrasound generating cavity, thereby changing the cavity air pressure to generate a standard low distortion infrasound sound pressure signal.
  • the laser vibrometer measures the displacement of the moving parts through the optical channel of the vibrating table to measure the displacement of the moving parts, thereby obtaining the standard sound pressure value; the piston and the cavity in the infrasound generating chamber are completely sealed or gap sealed.
  • the invention adopts the more mature vibration table technology to generate the subsonic frequency vibration, and introduces the displacement feedback control technology to reduce the distortion of the infrasound sound pressure signal.
  • the invention has the advantages that the used technology is mature, the feasibility is strong, the implementation is convenient, the calibration precision is high, and the like.
  • Fig. 1 is a structural view of an infrasound generating device based on a displacement feedback type vibrating table.
  • Figure 2 is a schematic diagram of the displacement feedback type shaker system.
  • Fig. 3 is a structural view showing the connection between the vibrating table and the infrasound generating chamber in the first embodiment.
  • FIG 4 is a structural view of an integrated sealing film used in the infrasound generating chamber of the first embodiment.
  • Figure 5 is a structural view showing the connection between the piston and the infrasound generating chamber in the second embodiment.
  • Embodiment 1 An infrasound generating device based on a displacement feedback type vibrating table, including a displacement feedback type vibrating table system, an infrasound generating chamber 3, and a laser vibrometer 1 for measuring the vibration displacement of the vibrating table 2, and a vibration displacement calculation obtained by the laser vibrometer 1
  • the standard sound pressure value generated by the infrasound generating chamber 3 is obtained.
  • the displacement feedback type shaking table system comprises a signal generator, a power amplifier and a vibration table 2 and a displacement feedback component;
  • the displacement feedback component comprises a displacement sensor 12 for measuring a displacement waveform of the moving part 22 of the vibration table 2, a comparison displacement waveform and a signal generator generation a comparator for deviation of a standard signal and a controller for calculating a deviation signal, and a signal conditioning circuit for modulating a displacement waveform between the displacement sensor and the comparator;
  • the deviation signal is obtained by subtracting the standard signal generated by the comparator and the signal generator.
  • the power amplifier is input, and the vibration table is driven to perform the correcting motion. Therefore, the output displacement of the vibrating table accurately tracks the waveform of the low-distortion signal source, reduces the distortion of the output waveform of the vibrating table, and further reduces the distortion of the output sound pressure signal of the infrasound generating device.
  • the vibrating table 2 is provided with an optical passage 16 that allows the measurement light 15 output from the laser vibrometer 1 to pass, and a reflector 13 that reflects the measurement light 15 back to the laser vibrometer 1.
  • the measurement light 15 is incident from the tail of the vibrating table 2, and is reflected.
  • the body 13 is fixed to the back surface of the moving member 22 of the vibrating table 2.
  • the infrasound generating chamber 3 is a closed cavity, and the infrasound generating chamber 3 is provided with a piston 31 adapted to the cavity.
  • the piston 31 is fixedly connected to the front surface of the moving part 22 of the vibrating table 2, and the calibrated infrasound sensor 4 is mounted on The infrasound occurs within the cavity 35 of the cavity 3.
  • the basic principle of the infrasound generating device is that in a closed cavity whose size is much smaller than the wavelength of the acoustic wave in the medium (the maximum size is 1/20 of the wavelength), the pressure wave is excited in the closed cavity by the movement of the piston, according to the law of adiabatic gas,
  • the sound field sound pressure generated by the infrasound generating chamber can be expressed as: 4 0
  • p is the sound pressure
  • y is the air specific heat ratio
  • ⁇ is the static pressure
  • ⁇ is the static pressure
  • X is the displacement of the piston movement
  • the standard sound pressure value obtained by Formula 1 is used as the calibration reference of the calibrated infrasound sensor 4, and only when the calibrated infrasound sensor 4 is mounted in the cavity 35 of the infrasound generating chamber 3, by detecting the output voltage of the sensor 4, Absolute calibration of the infrasound sensor can be achieved by combining the standard sound pressure values.
  • the voltage output from the standard infrasound sensor is used as a calibration reference for the calibrated infrasound sensor, and the standard infrasound sensor is simultaneously detected.
  • the relative calibration of the infrasound sensor can be achieved by calculating the output voltage of the infrasound sensor and calculating it.
  • the vibrating table 2 is an electromagnetic vibrating table, and the vibrating table 2 includes an exciting member 21, a moving member 22 and a guiding member 23; the exciting member 21 is a magnetic circuit structure composed of a permanent magnet or an electromagnet, and is operable in the working air gap 24.
  • a constant magnetic field is generated, and when the sinusoidal current is passed through the armature coil 25 of the moving member 22 in the working air gap 24, the ampere force generated by the electromagnetic induction drives the moving member to perform sinusoidal motion, and the guiding member 23 can be opposite to the moving member 22. Supporting and guiding are performed to limit the lateral movement other than the axial movement.
  • an air bearing is used as the guiding member of the moving part of the vibrating table.
  • the displacement sensor 12 is a grating scale, and the read head of the scale is fixed on the guiding member 23 of the electromagnetic vibration table, and the scale ruler is mounted on the moving member 22 of the vibration table 2.
  • the rear end of the vibrating table 2 is provided with a small hole for allowing the measurement light of the laser vibrometer to be incident, and the inside of the vibrating table 2 is also A through hole that passes through the vibrating table and the moving member 22 and allows the measurement of light to pass therethrough, the small hole at the tail of the vibrating table 2, the through hole that penetrates the exciting member 21 and the moving member form the allowable passage of the measuring light 15 Light channel 16.
  • the reflector 13 fixed on the back surface of the moving member 22 of the vibrating table 2 is a mirror or a reflecting film, and the measuring light 15 reflected by the reflecting body 13 is reflected back to the laser vibrometer 1 through the optical passage 16 to detect the moving part of the vibrating table 2. The displacement of 22.
  • the infrasound generating chamber 3 includes a cavity 35, a piston 31 adapted to the cavity 35, a piston end seal 32, a sensor mounting sealing cover 33, and a holder 34 and 36 for the holding cavity.
  • the piston 31 is connected to the front surface of the moving part 22 of the vibrating table, and the moving part 22 of the vibrating table drives the piston 31 to move in the cavity 35; the piston 31, the piston end sealing means 32, the sensor mounting sealing cover 33 and the cavity 35 constitute a sealed cavity body.
  • the sensor mounting sealing cover 33 is provided with a receiving hole for accommodating the calibrated infrasound sensor 4, and a sensor sealing sleeve 41 is disposed between the receiving hole and the calibrated infrasound sensor 4.
  • the calibrated infrasound sensor 4 is inserted into the sensor sealing sleeve 41, and the sensor sealing sleeve 41 is inserted into the accommodating hole.
  • the sensor mounting sealing cover is further provided with a receiving hole for accommodating a standard infrasound sensor, and a sensor sealing sleeve is disposed between the receiving hole and the standard infrasound sensor.
  • the piston end seal 32 includes an integral sealing film 14 and an annular seal for fixing the integrated sealing film 14 to the infrasound generating chamber 3, the annular seal including a fixing member 321 fixed to the infrasound generating chamber by screws and The integral sealing film is pressed against the annular pressure plate 322 on the fixing member;
  • the body sealing film 14 includes an outer ring 141 fixed to the annular sealing member, an inner ring 142 fixed to the piston 31, and an outer ring 141 and an inner ring
  • the rubber film 143 of the 142 is provided with a first mounting groove adapted to the outer ring 141, and the piston 32 is provided with a second mounting groove adapted to the inner ring 142.
  • the integrated sealing film 14 seals the piston 31 and the cavity 35 to form a completely sealed manner.
  • the infrasound generating device further comprises a laser vibrometer base 11 for mounting the laser vibrometer 1 , the installation
  • the laser vibrometer is placed on the base 11 of the laser vibrometer through its bottom adjustable leg 18, and the laser vibrator base 11 is placed on the foundation 10 through the shock absorber 17, and the vibrating table base 9 and the air chamber base 7 are adjustable.
  • the horn 5 is mounted on the foundation 10.
  • the level and height of the vibrating table base 9 and the cavity mounting base plate 8 are adjusted by the adjustable horn 5, and the level and height of the measuring light 15 can be adjusted by the bottom adjustable leg 18 of the laser vibrometer, and finally the laser vibration is maintained.
  • the meter 1 outputs the measuring light 15, the moving table 22 of the vibrating table 2, and the infrasound generating chamber 3 are coaxial.
  • the technical idea of the present invention is: using a vibration table 2 with a displacement feedback component to drive the piston 31 to perform a low-displacement sinusoidal vibration in the closed infrasound generating cavity 35, thereby changing the cavity air pressure to generate a standard low distortion infrasound Sound pressure signal; the laser vibrometer 1 measures the displacement of the moving member 22 by entering the measuring light 15 through the optical passage 16 of the vibrating table 2, thereby obtaining a standard sound pressure value.
  • the invention adopts the more mature vibration table technology to generate the subsonic frequency vibration, and introduces the displacement feedback control technology to reduce the distortion of the generated infrasound sound pressure signal.
  • the invention has the advantages that the used technology is mature, feasible, easy to implement, and has high calibration precision.
  • the piston mounting end of the infrasonic generating cavity body 35 is provided with a piston sleeve 37 that closely fits the cavity 35, and the sealing gap is only achieved by the matching gap between the piston sleeve 37 and the piston 31.
  • the rest of the structure is the same.
  • the piston sealing device only includes a piston sleeve 37 which closely cooperates with the infrasound generating cavity body 35, and the sealing gap is achieved by the matching gap between the piston sleeve 37 and the piston 31, instead of adopting an integrated sealing film to form a gap sealing manner.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

基于位移反馈型振动台的次声发生装置，包括位移反馈型振动台系统、次声发生腔（3）和激光测振仪（1）；振动台（2）采用位移反馈方式，驱动活塞（31）在密闭次声发生腔（3）的腔体（35）内做低位移失真的正弦振动，产生标准次声声压信号；激光测振仪（1）通过贯穿振动台（2）的光通道射入测量光（15），测量振动台（2）的运动部件（22）的位移，计算得到次声发生腔（3）产生的标准声压值，将该标准声压值作为被校准次声传感器（4）的校准基准，以实现对次声传感器的绝对校准；也可以在次声发生腔（3）内安装标准次声传感器，将标准次声传感器的输出作为被校准次声传感器（4）的校准基准，以实现对次声传感器的相对较准。该次声发生装置具有所用技术成熟，可行性强，便于实现，校准精度高的优点。

Description

说 明 书
基于位移反馈型振动台的次声发生装置
技术领域
本发明涉及一种次声发生装置， 特别是一种可产生标准次声声压信号、 用 于校准次声传感器的次声发生装置。
技术背景
次声波广泛存在于自然界和人类生产生活中， 如火山喷发、 地震、 核爆炸、 火箭发射、 超音速飞机飞行等均会产生次声波。 近年来， 次声检测在环境保护、 军事监察等领域越来越多地引起了人们的重视； 此外， 由于次声波具有传播距 离远、 穿透能力强、 不易察觉等特点， 次声波技术在军事、 医学、 工业生产等 领域的应用也越来越广泛。
次声传感器对于次声波的检测和应用至关重要。 为正确应用次声传感器， 按照计量检定规程的规定， 必须在出厂前或使用一段时间后， 对次声传感器的 灵敏度等各项性能指标进行校准。 次声传感器校准系统是发展次声传感器技术 的重要保证， 它是通过次声发生装置产生标准次声声压信号， 用"绝对法 "或"相 对法"对次声传感器进行校准。 次声发生装置是次声传感器校准系统的重要组成 部分， 其产生的次声声压信号质量将直接决定对次声传感器的校准精度。 目前 国内外次声发生装置多由电机或振动台直接带动活塞做往复运动产生正弦次声 声压， 但由于非线性参数的影响， 所产生的次声声压波形失真度较大， 从而影 响次声传感器的校准精度。
发明内容
为克服现有的次声发生装置存在波形失真度大的缺点， 本发明提供了一种 波形失真度小， 保障次声传感器的校准精度的基于位移反馈型振动台的次声发 生装置。
基于位移反馈型振动台的次声发生装置， 包括位移反馈型振动台系统， 次 声发生腔和测量振动台的振动位移的激光测振仪， 激光测振仪获取的振动位移 计算获得次声发生腔产生的标准声压值；
位移反馈型振动台系统包括信号发生器、 功率放大器、 振动台和位移反馈 组件； 位移反馈组件包括测量振动台的运动部件的位移波形的位移传感器、 比 较位移波形与信号发生器产生的标准信号的偏差的比较器和对偏差信号进行计 算处理的控制器， 位移传感器与比较器之间还设有调理位移波形的信号调理电 路； 位移传感器获取的位移波形经信号调理电路处理后， 经比较器与信号发生 器产生的标准信号相减得到偏差信号， 偏差信号经控制器计算处理后， 输入功 率放大器， 驱动振动台进行纠偏运动， 从而实现振动台输出位移精确跟踪低失 真的信号源波形， 降低了振动台输出位移波形的失真度， 进而降低次声发生装 置输出声压信号的失真度。
振动台设有允许激光测振仪的测量光通过的光通道和将测量光反射回激光 测振仪的反射体， 测量光从振动台的尾部入射， 反射体固定在振动台的运动部 件背面；
次声发生腔为密闭腔体， 次声发生腔内设有与腔体适配的活塞， 活塞与振 动台的运动部件的正面固定连接， 被校准次声传感器安装在次声发生腔的腔体 内。
次声发生装置的基本原理是在尺寸远小于媒质中声波波长的密闭腔中 (尺寸 最大是波长的 1/20)， 通过活塞的运动， 在密闭腔中激励出压力波， 根据绝热气 体定律， 次声发生腔产生声场声压可表示为： ρ = π ~ 公式 1 式中： p为声压； y为空气比热比；； ^为静压； 为活塞的直径； X为活塞运动的 位移； 为活塞平衡位置时的密闭腔的体积。 通过激光测振仪测得活塞位移 X 后， 代入上式可得密闭腔中的标准声压值， 进而实现绝对法校准次声传声器。 本装置中， 由于位移反馈型振动台可输出失真度较低的振动位移， 根据以上公 式得知， 可在次声发生腔中产生失真度较低的声压信号。
进一步， 以公式 1 得到的标准声压值作为被校准次声传感器的校准基准； 或者所述的次声发生腔内还设有标准次声传感器， 标准次声传感器的输出作为 被校准次声传感器的校准基准。
进一步， 所述的次声发生腔包括腔体、 与腔体适配的活塞、 活塞端密封装 置、 传感器安装密封盖和托持腔体的支座。
进一步， 所述的传感器安装密封盖上开设有容纳被校准次声传感器的容纳 孔， 容纳孔与被校准次声传感器之间设有传感器密封套筒。 若腔体内还设有标 准次声传感器， 所述的传感器安装密封盖上还开设有容纳标准次声传感器的容 纳孔， 容纳孔与标准次声传感器之间设有传感器密封套筒。
进一步， 活塞端密封装置包括一体化密封膜和将一体化密封膜固定在次声 发生腔上的环形密封件， 环形密封件包括通过螺钉固定在次声发生腔上的固定 件和将一体化密封膜压紧于固定件上的环形压板； 一体化密封膜包括与环形密 封件固接的外圈、 与活塞固接的内圈和连接外圈和内圈的橡胶膜， 固定件设有 与外圈适配的第一安装槽， 活塞上设有与内圈适配的第二安装槽。 采用一体化 密封膜密封活塞和腔体， 构成完全密封方式。
或者， 活塞端密封装置不设一体化密封膜， 仅有紧密地安装在腔体上的活 塞套， 仅靠活塞与活塞套之间的配合间隙实现密封， 构成间隙密封方式。 进一步， 所述的次声发生装置还包括安装激光测振仪的激光测振仪底座， 安装振动台的振动台底座， 安装次声发生腔的腔体安装底板， 和放置测量仪器 及其他工具的工作台面， 腔体安装底板和工作台面均安装在气腔底座上； 激光 测振仪通过其底部可调支脚放置在激光测振仪底座上， 激光测振仪底座通过减 震器放置在地基上， 振动台底座和气腔底座通过可调垫铁安装于地基上。 测量 仪器和其他工具是指在测量过程中需要使用的测量工具或辅助用具。
本发明的技术构思是： 采用带有位移反馈组件的振动台驱动活塞在密闭次 声发生腔腔体内做低位移失真的正弦振动， 进而改变腔体气压， 产生标准低失 真的次声声压信号； 激光测振仪通过振动台的光通道射入测量光来测量运动部 件的位移大小， 从而得到标准声压值； 次声发生腔中的活塞与腔体采用完全密 封或间隙密封两种形式。
本发明采用较成熟的振动台技术产生次声频率振动， 并引入位移反馈控制 技术， 降低产生次声声压信号的失真度。 本发明具有所用技术成熟， 可行性强， 便于实现， 校准精度高等优点。
附图说明
图 1为基于位移反馈型振动台的次声发生装置结构图。
图 2为位移反馈型振动台系统原理图。
图 3为实施例一中振动台与次声发生腔体连接结构图。
图 4为实施例一中次声发生腔采用的一体化密封膜结构图。
图 5为实施例二中活塞与次声发生腔体连接结构图。
具体实施方式
实施例一 基于位移反馈型振动台的次声发生装置， 包括位移反馈型振动台系统， 次 声发生腔 3和测量振动台 2的振动位移的激光测振仪 1，激光测振仪 1获取的振 动位移计算获得次声发生腔 3产生的标准声压值。
位移反馈型振动台系统包括信号发生器、 功率放大器和振动台 2 和位移反 馈组件； 位移反馈组件包括测量振动台 2的运动部件 22的位移波形的位移传感 器 12、 比较位移波形与信号发生器产生的标准信号的偏差的比较器和对偏差信 号进行计算处理的控制器， 位移传感器与比较器之间设有调理位移波形的信号 调理电路；
位移传感器获取的位移波形经信号调理电路处理后， 经比较器与信号发生 器产生的标准信号相减得到偏差信号， 偏差信号经控制器计算处理后， 输入功 率放大器， 驱动振动台进行纠偏运动， 从而实现振动台输出位移精确跟踪低失 真的信号源波形， 降低了振动台输出位移波形的失真度， 进而降低次声发生装 置输出声压信号的失真度。
振动台 2设有允许激光测振仪 1输出的测量光 15通过的光通道 16和将测 量光 15反射回激光测振仪 1的反射体 13， 测量光 15从振动台 2的尾部入射， 反射体 13固定在振动台 2的运动部件 22的背面。
次声发生腔 3为密闭腔体， 次声发生腔 3内设有与腔体适配的活塞 31， 活 塞 31与振动台 2的运动部件 22的正面固定连接， 被校准次声传感器 4安装在 次声发生腔 3的腔体 35内。
次声发生装置的基本原理是在尺寸远小于媒质中声波波长的密闭腔中 (尺寸 最大是波长的 1/20)， 通过活塞的运动， 在密闭腔中激励出压力波， 根据绝热气 体定律， 次声发生腔产生声场声压可表示为： 4 0
式中： p为声压； y为空气比热比；； ^为静压； 为活塞的直径； X为活塞运动的 位移； 为活塞平衡位置时的密闭腔的体积。 通过激光测振仪测得活塞位移 X 后， 代入上式可得密闭腔中的标准声压值， 进而实现绝对法校准次声传声器。 本装置中， 由于位移反馈型振动台可输出失真度较低的振动位移， 根据以上公 式得知， 可在次声发生腔中产生失真度较低的声压信号。
以公式 1得到的标准声压值作为被校准次声传感器 4的校准基准， 仅被校 准次声传感器 4安装在次声发生腔 3的腔体 35内时， 通过检测被校传感器 4输 出电压， 并结合标准声压值即可实现对次声传感器的绝对校准。
当标准次声传感器和被校准次声传感器同时安装在次声发生腔 3腔体 35内 时， 将标准次声传感器输出的电压作为被校准次声传感器的校准基准， 通过同 时检测标准次声传感器和被校准次声传感器的输出电压， 并通过计算即可实现 对次声传感器的相对校准。
所述的振动台 2为电磁振动台， 振动台 2包括励磁部件 21、运动部件 22和 导向部件 23; 励磁部件 21为由永磁体或电磁铁构成的磁路结构， 可在工作气隙 24内产生恒定磁场，当工作气隙 24内的运动部件 22的电枢线圈 25中通过正弦 电流时， 由电磁感应产生的安培力驱动运动部件进行正弦运动， 所述的导向部 件 23可对运动部件 22进行支撑和导向， 限制其轴向运动以外的横向运动， 本 实施例中采用气浮轴承作为振动台运动部件的导向部件。
所述的位移传感器 12为光栅尺， 光栅尺的读数头固定在电磁振动台的导向 部件 23上， 光栅尺标尺安装在振动台 2的运动部件 22上。
振动台 2尾部设有允许激光测振仪的测量光入射的小孔， 振动台 2内部还 设有贯通振动台的励磁部件 21和运动部件 22且允许测量光通过的通孔， 振动 台 2尾部的小孔、贯通励磁部件 21和运动部件的通孔形成所述的允许测量光 15 通过的光通道 16。 固定在振动台 2的运动部件 22背面上的反射体 13为反射镜 或者反射膜， 反射体 13反射的测量光 15经光通道 16反射回激光测振仪 1， 以 检测振动台 2的运动部件 22的位移。
所述的次声发生腔 3包括腔体 35、 与腔体 35适配的活塞 31、 活塞端密封 装置 32、 传感器安装密封盖 33和托持腔体的支座 34和 36。 活塞 31与振动台 的运动部件 22的正面相连， 振动台的运动部件 22驱动活塞 31在腔体 35内运 动； 活塞 31、 活塞端密封装置 32、 传感器安装密封盖 33和腔体 35构成密封腔 体。
所述的传感器安装密封盖 33上开设有容纳被校准次声传感器 4的容纳孔， 容纳孔与被校准次声传感器 4之间设有传感器密封套筒 41。 被校准次声传感器 4插入传感器密封套筒 41中， 传感器密封套筒 41插入容纳孔中。若腔体内还设 有标准次声传感器， 所述的传感器安装密封盖上还开设有容纳标准次声传感器 的容纳孔， 容纳孔与标准次声传感器之间设有传感器密封套筒。
活塞端密封装置 32包括一体化密封膜 14和将一体化密封膜 14固定在次声 发生腔 3 上的环形密封件， 环形密封件包括通过螺钉固定在次声发生腔上的固 定件 321和将一体化密封膜压紧于固定件上的环形压板 322; —体化密封膜 14 包括与环形密封件固接的外圈 141、 与活塞 31固接的内圈 142和连接外圈 141 和内圈 142的橡胶膜 143， 固定件设有与外圈 141适配的第一安装槽， 活塞 32 上设有与内圈 142适配的第二安装槽。 采用一体化密封膜 14密封活塞 31和腔 体 35， 构成完全密封方式。
所述的次声发生装置还包括安装激光测振仪 1 的激光测振仪底座 11， 安装 振动台 2的振动台底座 9，安装次声发生腔 3的腔体安装底板 8和放置测量仪器 及其他工具的工作台面 6;腔体安装底板 8和工作台面 6均安装在气腔底座 7上； 激光测振仪通过其底部可调支脚 18放置在激光测振仪底座 11上， 激光测振仪 底座 11通过减震器 17放置在地基 10上、 振动台底座 9和气腔底座 7通过可调 垫铁 5安装于地基 10上。 通过可调垫铁 5来调整振动台底座 9和腔体安装底板 8的水平度和高度，通过激光测振仪底部可调支脚 18可调整测量光 15的水平度 和高低， 最终保持激光测振仪 1输出测量光 15、振动台 2运动部件 22和次声发 生腔 3同轴。
本发明的技术构思是： 采用带有位移反馈组件的振动台 2驱动活塞 31在密 闭次声发生腔体 35内做低位移失真的正弦振动， 进而改变腔体气压， 产生标准 低失真的次声声压信号；激光测振仪 1通过振动台 2的光通道 16射入测量光 15 来测量运动部件 22的位移大小， 从而得到标准声压值。
本发明采用较成熟的振动台技术产生次声频率振动， 并引入位移反馈控制 技术， 降低了产生的次声声压信号的失真度。 本发明具有所用技术成熟， 可行 性强， 便于实现， 校准精度高等优点。
实施例二
本实施例与实施例一的区别在于： 在次声发生腔腔体 35的活塞安装端设有 与腔体 35紧密配合的活塞套 37，而仅靠活塞套 37和活塞 31的配合间隙实现密 封， 其余结构都相同。
所述的活塞密封装置仅包含与次声发生腔腔体 35紧密配合的活塞套 37，靠 活塞套 37与活塞 31 的配合间隙实现密封， 而不采用一体化密封膜， 构成间隙 密封方式。
本说明书实施例所述的内容仅仅是对发明构思的实现形式的列举， 本发明 的保护范围不应当被视为仅限于实施例所陈述的具体形式， 本发明的保护范围 也及于本领域技术人员根据本发明构思所能够想到的等同技术手段。

Claims

权利要求书
1、 基于位移反馈型振动台的次声发生装置， 其特征在于： 包括位移反馈型 振动台系统， 次声发生腔和测量振动台的振动位移的激光测振仪， 激光测振仪 获取的振动位移计算获得次声发生腔产生的标准声压值 p = π-γ ^±，；？为声压， y为空气比热比， ； ^为静压， 为活塞的直径， X为活塞运动的位移， 为活塞 平衡位置时的密闭腔的体积；
位移反馈型振动台系统包括信号发生器、 功率放大器和振动台和位移反馈 组件； 位移反馈组件包括测量振动台的运动部件的位移波形的位移传感器、 比 较位移波形与信号发生器产生的标准信号的偏差的比较器和对偏差信号进行计 算处理的控制器， 位移传感器与比较器之间设有调理位移波形的信号调理电路; 振动台的运动部件受控于控制器， 控制器与振动台之间设有放大控制器输出的 控制信号的功率放大器；
振动台设有允许激光测振仪的测量光通过的光通道和将测量光反射回激光 测振仪的反射体， 测量光从振动台的尾部入射， 反射体固定在振动台的运动部 件背面；
次声发生腔为密闭腔体， 次声发生腔内设有与腔体适配的活塞， 活塞与振 动台的运动部件的正面固定连接， 被校准次声传感器安装在次声发生腔的腔体 内。
2、 如权利要求 1所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 激光测振仪获取振动位移计算得到的标准声压值作为被校准次声传感器的 校准基准.
3、 如权利要求 1所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 所述的次声发生腔内还设有标准次声传感器， 标准次声传感器的输出作为 被校准次声传感器的校准基准。
4、 如权利要求 1所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 所述的次声发生腔包括腔体、 与腔体适配的活塞、 活塞端密封装置、 传感 器安装密封盖和托持腔体的支座。
5、 如权利要求 4所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 所述的传感器安装密封盖上开设有容纳被校准次声传感器的第一容纳孔， 第一容纳孔与被校准次声传感器之间设有第一传感器密封套筒。
6、 如权利要求 5所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 当腔体内还设有标准次声传感器时， 传感器安装密封盖上还开设有容纳标 准次声传感器的第二容纳孔， 第二容纳孔与标准次声传感器之间设有第二传感 器密封套筒。
7、 如权利要求 4所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 活塞端密封装置包括一体化密封膜和将一体化密封膜固定在次声发生腔上 的环形密封件， 环形密封件包括通过螺钉固定在次声发生腔上的固定件和将一 体化密封膜压紧于固定件上的环形压板； 一体化密封膜包括与环形密封件固接 的外圈、 与活塞固接的内圈和连接外圈和内圈的橡胶膜， 固定件设有与外圈适 配的第一安装槽， 活塞上设有与内圈适配的第二安装槽。
8、 如权利要求 4所述的基于位移反馈型振动台的次声发生装置， 其特征在 于： 活塞端密封装置仅包括紧密地安装在腔体上的活塞套， 活塞与活塞套仅靠 配合间隙实现密封。
9、 如权利要求 1-8之一所述的基于位移反馈型振动台的次声发生装置， 其 特征在于： 所述的次声发生装置还包括安装激光测振仪的激光测振仪底座， 安 装振动台的振动台底座， 安装次声发生腔的腔体安装底板， 和放置测量仪器及 其他工具的工作台面， 腔体安装底板和工作台面均安装在气腔底座上； 激光测 振仪底部设有可调支脚， 激光测振仪和可调支脚放置激光测振仪底座上， 激光 测振仪底座通过减震器放置在地基上， 振动台底座和气腔底座通过可调垫铁安 装于地基上。
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