A Doppler effect-based frequency shifting device, muffling device and method

Abstract

A frequency shifting device based on the Doppler effect, a noise bypass frequency shifting device based on the receiver, a composite noise reduction device, and a method are disclosed. The frequency shifting device based on the Doppler effect includes: a rotor module (101) with a noise port, the noise port including a first noise port (10101) and a second noise port (10102). The first noise port (10101) is connected to the second noise port (10102) on the noise propagation path. The first noise port (10101) is used to connect to a sound source or output frequency-shifted noise. The second noise port (10102) follows the rotor module (101) in a periodic motion relative to a reference frame, causing a Doppler effect due to the relative motion between the second noise port (10102) and the noise source. This results in a frequency shift in the transmission or reception frequency relative to the reference frame. The frequency shift of the second noise port (10102) relative to the reference frame is controlled by changing the speed of the periodic motion. The reference frame includes an inertial reference frame and a non-inertial reference frame. This invention addresses the technical deficiency of existing general-purpose silencer technology, which suffers from the invariability of silencing characteristics due to limitations in material properties or structural design. It realizes a new type of silencer with variable silencing characteristics, namely, a frequency shifting device, silencing equipment, and method based on the Doppler effect.

Description

A frequency shift device, noise elimination device and method based on Doppler effect Technical Field

[0001] The present invention relates to a frequency shift device, noise elimination equipment and method based on Doppler effect. Background Art

[0002] The Doppler effect is the change in the wavelength of sound waves emitted by a source due to the relative motion between the source and the observer. In front of the moving source, the waves are compressed, resulting in a shorter wavelength and a higher frequency. Behind the moving source, the opposite effect occurs: the wavelength becomes longer and the frequency becomes lower. The higher the relative speed, the greater the effect.

[0003] General silencers can be divided into two categories according to their noise reduction principles: resistive and reactive. These two types of silencers have different noise reduction characteristics. Resistive silencers are mainly used to eliminate medium and high frequency noise, while reactive silencers are mainly used to eliminate medium and low frequency noise. The noise reduction principle of the above-mentioned resistive silencer is to use the sound-absorbing material installed on the pipe wall, or the sound-absorbing effect of the sound-absorbing structure arranged and combined in a certain way in the pipe, so that the noise energy propagating along the pipe is converted into heat energy and attenuated, thereby achieving the purpose of noise reduction. However, the resistive silencer in the prior art has the technical defect of insufficient low-frequency noise performance; and the noise reduction principle of the above-mentioned reactive silencer is not to directly absorb sound energy, but to use the protruding expansion or contraction of the pipe cross-section, or the side resonance cavity, so that part of the noise propagating along the pipe is reflected back toward the sound source at the mutation point without passing through the silencer, thereby achieving the purpose of noise reduction. However, the reactive silencer in the prior art has the technical defect of insufficient high-frequency noise reduction performance, especially when the reactive silencer works in the medium and low frequency bands, because of its technical requirements for sound volume and sound quality, there is also a technical defect of large structural volume.

[0004] More importantly, the existing general silencer technology also has the technical defect of unchangeable sound-absorbing characteristics due to the constraints of material properties or structural construction. Once the material parameters and structural parameters are determined, the sound-absorbing characteristics of the general silencer constituted by them are fixed. For example, the resistive silencer includes a sound-absorbing material installed on the pipe wall. Once the sound-absorbing material is determined, the sound-absorbing characteristics of the resistive silencer are determined, and the sound-absorbing material's absorption performance for low-frequency noise is far lower than its absorption performance for high-frequency noise. Modifying the sound-absorbing material cannot fundamentally improve the sound-absorbing performance of the resistive silencer for low-frequency noise.

[0005] Another example is the Helmholtz resonance silencer in the reactive silencer, which includes a closed cavity and a neck tube. Once the sound volume of the closed cavity and the sound mass of the neck tube are determined, the sound attenuation characteristic parameters (including the sound attenuation amount, bandwidth and maximum sound attenuation frequency) are determined. It can only silence noise within a fixed frequency band. When it is necessary to silence noise below the maximum sound attenuation frequency, the aforementioned sound volume or sound mass can only be modified, which is equivalent to modifying the structural volume of the closed cavity or the structural geometric parameters such as the length and diameter of the neck tube. Moreover, the lower the noise frequency, the larger the structural volume of the closed cavity or the longer the neck tube and the smaller the diameter of the neck tube, which in turn leads to the technical defect of a larger volume of the silencer.

[0006] Another example is the expansion muffler in the reactive muffler, which includes an expansion chamber and a tube. Once the sound volume of the expansion chamber and the sound mass of the tube are determined, its muffler characteristic parameters (including the muffler volume, bandwidth and maximum muffler frequency) are determined. It can only muffle the noise within a fixed muffler section. When it is necessary to muffle the noise below the maximum muffler frequency, the structural length of the expansion chamber can only be modified. Moreover, the lower the noise frequency, the larger the structural length of the expansion chamber is required, which in turn leads to the technical defect of a larger volume of the muffler.

[0007] In summary, the industry has long been looking forward to the emergence of a new type of silencer with variable silencer characteristics, that is, after the material parameters and structural parameters are determined, the silencer characteristics of the silencer constituted by it can be changed. For example, the first maximum silencer frequency of the expansion silencer of the resistive silencer can be changed, thereby overcoming the defect of the immutable silencer characteristics caused by the structural construction characteristics, and at the same time overcoming the disadvantage that the lower the noise frequency, the larger the volume of the resistive silencer is required; for example, for the resistive silencer, the defect of low low-frequency silencer performance caused by the characteristics of the sound-absorbing material can be overcome. Therefore, it is necessary to propose a new type of silencer device and method, that is, a frequency shift device, silencer equipment and method based on the Doppler effect. Summary of the Invention

[0008] The purpose of the present invention is to address the technical defects of the existing general muffler, such as the unchangeable muffler characteristics and the large structural size, and to provide a frequency shift device, a muffler device and a method based on the Doppler effect, comprising a rotor module with a noise port, wherein the noise port comprises a first noise port and a second noise port, wherein the first noise port is connected to the second noise port on the noise propagation path, wherein the first noise port is used to connect to a sound source or output frequency-shifted noise, and the second noise port follows the rotor module in periodic motion relative to the reference frame, so that the second noise port and the noise source move relative to each other and Doppler occurs. The invention relates to a frequency shift effect, which causes a frequency shift of the transmitting or receiving frequency relative to the reference system, thereby controlling the frequency shift of the second noise port relative to the reference system by changing the speed of the periodic motion. The reference system includes an inertial reference system and a non-inertial reference system, which solves the technical defects of the existing general silencer technology that the inherent noise reduction characteristics are immutable due to the constraints of material properties or structural structures and the deficiency of large structural structure size. That is, when the material parameters and structural parameters are determined, the noise reduction characteristics of the existing general technology silencer constituted by it are immutable, thereby realizing a frequency shift device, noise reduction equipment and method based on the Doppler effect. Doppler effect

[0009] Assuming the speed of sound is c, when the frequency is The noise source (transmitter) moves at a speed u, and the universal silencer (receiver) moves at a speed v, then the receiving frequency of the universal silencer is , is positive when the directions of motion of u and v make the universal muffler and the noise source close to each other, and the frequency shift factor From the above receiving frequency formula, we can know that when v or u increases in the positive direction, Rapid increase, for example, when u=v=-0.2c, ; When u=v=0.2c, ; When u=v=0.8c, .

[0010] .When the frequency of the noise source (emitter) remains unchanged, and u=v=0.2c is set, assuming that the universal muffler is a Helmholtz resonance muffler composed of a neck tube connecting a closed cavity, if the structural dimensions of the neck tube remain unchanged, the volume of the closed cavity can be reduced by 33.3%; assuming that the universal muffler is an expansion muffler composed of a tube connecting an expansion chamber, the structural length of the expansion chamber can be reduced by 33.3%; assuming that the universal muffler is a resistive muffler, because the sound-absorbing material's absorption performance for high-frequency noise is much greater than its absorption performance for low-frequency noise f, the noise reduction capacity of the resistive universal muffler against the noise source (emitter) can be significantly improved.

[0011] On the other hand, if the structure or material of the universal muffler remains unchanged, then by controlling the relative motion between the universal muffler and the noise source, the receiving frequency of the universal muffler can be changed, that is, the muffler characteristics of the new muffler provided by the present invention are changed. For example, assuming that the universal muffler has the maximum sound absorption frequency f c =200Hz Helmholtz resonance muffler, when u=v=0.2c, for the noise source (emitter), the maximum sound absorption frequency of the frequency shift device, muffler equipment and method based on the Doppler effect provided by the present invention changes to f c / 1.5; When u=v=-0.2c, for the noise source (emitter), the maximum sound absorption frequency of the frequency shift device, noise elimination device and method based on the Doppler effect provided by the present invention changes to 1.5×f c Therefore, the present invention provides a frequency shift device, noise reduction device and method based on the Doppler effect with variable noise reduction characteristics. Frequency shift rotor module

[0012] As shown in Figures 1 and 2, the first rotor module 101 includes a first noise port 10101 and a second noise port 10102, wherein the first noise port 10101 is used to connect to an external sound source or to output frequency-shifted noise, and the second noise port 10102 causes the noise to produce a Doppler frequency shift effect; the first rotor module 101 rotates around the rotation axis 103 at an angular velocity ω, because the second noise port 10102 is closer to the rotation axis 103 than the first noise port 10101. The vertical distance is larger, so the second noise port 10102 has a larger linear velocity u or v than the first noise port 10101. Assuming that the positive path of noise propagation is defined as from the first noise port 10101 to the second noise port 10102, and the negative path of noise propagation is from the second noise port 10102 to the first noise port 10101, then when the noise propagation path is positive, the linear velocity of the second noise port 10102 is u, and the frequency shift factor is , where c is the speed of sound, the first rotor module-101 constitutes the transmitting end noise frequency shift device, and when the linear velocity u of the second noise port-10102 is in the same direction as the noise propagation path, u is positive, otherwise u is negative; when the noise propagation path is negative, the linear velocity of the second noise port-10102 is v, and the frequency shift factor is , where c is the speed of sound, the first rotor module-101 constitutes a receiving-end noise frequency shifting device, and when the linear velocity v of the second noise port-10102 is in the same direction as the noise propagation path, v is negative, otherwise v is positive.

[0013] It is understood that noise propagates in a medium, which can have a flow velocity. The kinetic energy of the medium's flow drives the first rotor module 101 to rotate about the rotation axis 103. As shown in Figures 24 and 25, the structural axis 104 of the second noise port 10102, through which the noise medium flows, is non-parallel to the rotation axis 103, but rather has a non-perpendicular angle. This causes the medium's momentum to generate a component in a plane perpendicular to the rotation axis 103, which drives the first rotor module 101 to rotate about the rotation axis 103. In other words, the flow path of the noise medium flowing through the second noise port 10102 is non-parallel to the rotation axis 103 of the second noise port, causing the medium's momentum to generate a momentum component in a plane perpendicular to the rotation axis 103, which drives the first rotor module to rotate about the rotation axis.

[0014] It can be understood that the driving source that drives the first rotor module-101 to rotate around the rotating shaft-103 includes existing engine technologies such as electric motors, fluid power (including windmills, fans, fluid turbines, hydraulic turbines, and water turbines), internal combustion engines, and external combustion engines. Its transmission methods include both mechanical contact transmissions such as shafts, gears, and chains, and contactless transmissions such as electromagnetic force, wind power, hydraulic force, and fluid force. When it is a contact transmission, the rotating shaft-103 can be regarded as a mechanical transmission rod. When it is a contactless transmission, the rotating shaft-103 can be regarded as a mechanical rotating axis in a non-material form. In order to fully disclose and highlight the core technical features of this application, the rotating shaft-103 is expressed abstractly in the following description and the drawings in the specification, and no distinction is made between the transmission method and the material form. Single-stage noise frequency shifter

[0015] The noise frequency shift device shown in Figures 1 and 2 can only control or constrain the noise propagation path inside the first rotor module-101, that is, the noise propagation path between the first noise port-10101 and the second noise port-10102, but cannot control or constrain the interaction between the noise propagation path connected to the second noise port-10102 and located outside the first rotor module-101 and the trajectory of the linear velocity of the second noise port-10102. There is a technical defect that the optimal Doppler frequency shift effect cannot be obtained. Therefore, it is necessary to improve the noise frequency shift device shown in Figures 1 and 2 into a single-stage noise frequency shift device, as shown in Figures 3, 4 and 5, by adding a first stator module-102, and optionally adding multiple The first stator module 102 includes a second noise port 10102, and the first stator module 102 includes a third noise port 10203. The first tube 10201 structure forms an acoustic cavity within the first stator module 102 along the motion trajectory of the second noise port 10102. This acoustic cavity interconnects and interacts the noise propagation path with the motion trajectory of the second noise port 10102. Along the tangent direction of the propagation path constrained by the first tube 10201 within the first stator module 102, the noise propagation direction is parallel to the linear velocity direction of the second noise port 10102, maximizing the linear velocity u or v and achieving an optimal Doppler shift effect. The first tube 10201 connects to the third noise port 10203. When the noise propagation path is positive, the third noise port 10203 functions as a frequency shift noise output port. Otherwise, when the noise propagation path is negative, the third noise port 10203 functions as a noise input port.

[0016] Assuming that the positive path of noise propagation is defined as from the first noise port 10101 through the second noise port 10102 to the third noise port 10203, and the negative path of noise propagation is from the third noise port 10203 through the second noise port 10102 to the first noise port 10101, then when the noise propagation path is positive, the linear velocity of the second noise port 10102 is u, and the frequency shift factor is , where c is the speed of sound, the single-stage noise frequency shift device constitutes the transmitting end noise frequency shift device, and when the linear velocity u of the second noise port-10102 is in the same direction as the noise propagation path, u is positive, otherwise u is negative; when the noise propagation path is negative, the linear velocity of the second noise port-10102 is v, and the frequency shift factor is , where c is the speed of sound. The single-stage noise frequency shifting device constitutes a receiving-end noise frequency shifting device. When the linear velocity v of the second noise port 10102 is in the same direction as the noise propagation path, v is negative; otherwise, v is positive. The linear velocity u or v = ωr, where r is the vertical distance from the second noise port 10102 to the rotation axis 103, and ω is the angular velocity of the second noise port 10102 about the rotation axis 103.

[0017] It can be understood that one of the reference systems of the periodic motion of the first rotor module-101 is the first stator module-102, and the acoustic structure of the first tube-10201 makes the noise propagation path one-dimensional. There is a relative relationship of the same direction and opposite direction between the tangential direction of the noise propagation path and the linear velocity direction of the second noise port-10102.

[0018] The noise frequency shifting device shown in Figures 3, 4, and 5 has certain technical drawbacks or deficiencies in connection with an external noise transmission pipeline because the first noise port 10101 rotates relative to the first stator module 102 or the reference frame. Therefore, it is necessary to improve the noise frequency shifting device shown in Figures 3, 4, and 5. As shown in Figures 6, 7, and 8, a fourth noise port 10204 is added to the first stator module 102 and connected to the first noise port 10101 to address the technical drawbacks or deficiencies. When the noise propagation path is positive, the fourth noise port 10204 serves as a noise input port, and noise is transmitted from the fourth noise port 10204 to the first noise port 10101. Otherwise, when the noise propagation path is negative, the fourth noise port 10204 serves as a frequency-shifted noise output port, and noise is transmitted from the first noise port 10101 to the fourth noise port 10204.

[0019] It is understandable that the first rotor 101 that rotates periodically generates mechanical vibration noise and aerodynamic noise, but the frequency spectrum thereof is concentrated. The use of a universal muffler can both reduce and silence the mechanical vibration noise and aerodynamic noise in a targeted manner.

[0020] It is understandable that the noise output port of the noise frequency shifting device can be connected to a universal muffler, and the two together constitute an acoustic system with variable muffler characteristics achieved by changing the speed of periodic mechanical motion. Serial cascade noise frequency shifting device

[0021] Because there is an upper limit to the angular velocity ω of the first rotor module-101 rotating around the rotation axis-103, the frequency shift factor of the aforementioned single-stage noise frequency shift device also has a frequency shift upper limit of about 8-10 times in engineering applications. In order to overcome this frequency shift upper limit, multiple single-stage noise frequency shift devices are connected in a serial cascade manner. The transmitting-end noise frequency shift device is abbreviated as T, and the receiving-end noise frequency shift device is abbreviated as R. The combination of the upper and lower stage noise frequency shift devices includes TT type, RR type and TR type.

[0022] As shown in Figures 9 and 10, for the convenience of analysis, it is assumed that the mechanical and acoustic characteristics of the upper and lower noise frequency shift devices are the same. The angular velocity ω1 of the upper stage's rotation axis-10301 and the angular velocity ω2 of the lower stage's rotation axis-10302 are equal, that is, ω1=ω2. Therefore, the linear velocity v1 of the upper stage's second noise port-1010201 and the linear velocity v2 of the lower stage's second noise port-1010202 are equal, that is, v1=v2=v ω , where v ω =ωr1, r1 is the vertical distance from the second noise port -1010201 to the rotation axis -10301. When the noise propagation path is in the positive direction, the noise propagation path is from the fourth noise port 1020401 of the previous stage to the third noise port 1020302 of the next stage. The upper and lower stages are both transmitting end noise frequency shift devices and constitute the aforementioned TT type combination. Its two-stage frequency shift factor , where c is the speed of sound, u=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, u is positive, otherwise u is negative; when the noise propagation path is negative, the noise propagation path is from the third noise port 1020302 of the next stage to the fourth noise port 1020401 of the previous stage. The upper and lower stages are both receiving end noise frequency shift devices and constitute the aforementioned RR type combination. Its two-stage frequency shift factor , where c is the speed of sound, v=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, v is negative, otherwise v is positive.

[0023] As shown in Figures 11 and 12, for the convenience of analysis, it is assumed that the mechanical and acoustic characteristics of the upper and lower noise frequency shift devices are the same. The angular velocity ω1 of the upper stage's rotation axis-10301 and the angular velocity ω2 of the lower stage's rotation axis-10302 are equal, that is, ω1=ω2. Therefore, the linear velocity v1 of the upper stage's second noise port-1010201 and the linear velocity v2 of the lower stage's second noise port-1010202 are equal, that is, v1=v2=v ω , where v ω=ωr1, r1 is the vertical distance from the second noise port -1010201 to the rotation axis -10301. When the noise propagation path is in the positive direction, the noise propagation path is from the fourth noise port 1020401 of the previous stage to the fourth noise port 1020402 of the next stage. The upper and lower stages are respectively the transmitting end noise frequency shift device and the receiving end noise frequency shift device, which constitute the aforementioned TR type combination. Its two-stage frequency shift factor , where c is the speed of sound, u=v=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, the upper level linear velocity u is positive and the lower level linear velocity v is negative, otherwise u is negative and v is positive; when the noise propagation path is negative, due to the structural and acoustic symmetry, the acoustic frequency shift characteristics of the serial cascade noise frequency shift device are equivalent to or the same as when the noise propagation path is positive.

[0024] It is understandable that when n noise frequency shifting devices are serially cascaded, assuming that the frequency shift factor of the i-th stage is k i , then the frequency shift factor k of the n-stage serial cascade noise frequency shift device is total is the product of multiple frequency shift factors, that is, k total =∏1 n k i where i=1, 2, 3.....n-1, n, the spectrum range of audible sound is [20Hz, 20kHz], when k total When k is greater than 1000, the audible sound frequency is transferred to the ultrasonic frequency band. total When the frequency is less than 1 / 1000, the audible sound frequency is transferred to the infrasound frequency band, making the noise become inaudible sound waves. Therefore, the serial cascade frequency shift device can be used independently as a new type of silencer different from the general silencer. total When the range is [1, 1000], a universal silencer can be connected to the aforementioned noise output port to form a noise-absorbing acoustic system. Since the noise frequency is increased by frequency shift, the structural geometric volume of the universal silencer can be reduced. More importantly, the noise-absorbing characteristics of the acoustic system composed of the frequency shift device and the universal silencer can be changed by controlling the speed of the periodic mechanical motion.

[0025] It can be understood that the universal muffler includes resistive muffler, reactive muffler and micro-perforated plate type, Helmholtz resonance muffler, micro-perforated plate resonance muffler, and perforated plate resonance muffler.

[0026] It can be understood that the aforementioned two-stage serial cascade noise frequency shift device shown in Figures 11 and 12 uses independent rotating shafts - 10301 and 10302 respectively, which will make the drive system complicated and not conducive to the compactness and miniaturization of the muffler structure. In view of this technical deficiency, it is improved to a coaxial serial cascade noise frequency shift device, as shown in Figures 13 and 14, which connects the first rotor module of the upper-stage frequency shift device to the first rotor module of the lower-stage frequency shift device, so that the upper and lower rotor modules use the same rotating shaft - 10301 to perform periodic motion together. For the convenience of analysis, it is assumed that the mechanical and acoustic characteristics of the upper and lower noise frequency shift devices are the same, and the two-stage frequency shift factor , where c is the speed of sound, u=v=v ω , where v ω =ωr, r is the vertical distance from the second noise port-1010201 to the rotation axis-10301, and when the linear velocity v ω When the direction is the same as the noise propagation path, u is positive and v is negative, otherwise u is negative and v is positive.

[0027] It is understandable that the first rotor 101 that rotates periodically generates mechanical vibration noise and aerodynamic noise, but the frequency spectrum thereof is concentrated. The use of a universal muffler can both reduce and silence the mechanical vibration noise and aerodynamic noise in a targeted manner.

[0028] It is understandable that the noise output port of the noise frequency shifting device can be connected to a universal muffler, and the two together constitute an acoustic system with variable muffler characteristics achieved by changing the speed of periodic mechanical motion. Bypass noise frequency shifter

[0029] The aforementioned single-stage noise frequency shift device and serial cascade noise frequency shift device are connected to the noise transmission pipeline network in a serial connection manner, while there is a bypass access working condition requirement in engineering applications. As shown in Figures 15, 16 and 17, the present invention proposes a noise bypass frequency shift device based on the receiving end, including a first rotor module-101 and a first stator module-102, and the first rotor module-101 performs periodic motion around the rotation axis-103 relative to the first stator module-102; the first rotor module-101 also includes a first noise port-10101 and a second noise port-10102, wherein the second noise port-10102 is used to cause the noise to produce a Doppler frequency shift effect; the first stator module-102 includes a third noise The sound port 10203 and the fifth noise port 10205; the second noise port 10102 is connected to the first noise port 10101, the third noise port 10203 and the fifth noise port 10205 respectively on the noise propagation path; the bypass path of noise propagation is from the third noise port 10203 through the second noise port 10102 to the first noise port 10101, and the straight path of noise propagation is from the third noise port 10203 to the fifth noise port 10205; the third noise port 10203 is the noise input port, the fifth noise port 10205 is the noise output port, and the first noise port 10101 is the frequency shift noise output port. The linear velocity of the second noise port 10102 is v, and the frequency shift factor is . , where c is the speed of sound, and when the linear velocity v is opposite to the direction of the noise propagation path, v is a positive value, otherwise v is a negative value.

[0030] It can be understood that, in the bypass noise frequency shifting device shown in Figures 15, 16 and 17, since the first noise port 10101 rotates relative to the first stator module 102 or the reference system, there are certain technical disadvantages or shortcomings in connecting the first noise port 10101 to the external noise transmission pipeline. Therefore, it is necessary to improve the bypass noise frequency shifting device shown in Figures 15, 16 and 17. As shown in Figures 18, 19 and 20, a fourth noise port 10204 is added to the first stator module 102 and connected to the first noise port 10101 to solve the technical disadvantages or shortcomings. When the noise propagation path is positive, the fourth noise port 10204 is the noise input port. Conversely, when the noise propagation path is negative, the fourth noise port 10204 is the frequency shift noise output port.

[0031] It is understandable that the first rotor 101 that rotates periodically generates mechanical vibration noise and aerodynamic noise, but the frequency spectrum thereof is concentrated. The use of a universal muffler can both reduce and silence the mechanical vibration noise and aerodynamic noise in a targeted manner.

[0032] It is understandable that the noise output port of the noise frequency shifting device can be connected to a universal muffler, and the two together constitute an acoustic system with variable muffler characteristics achieved by changing the speed of periodic mechanical motion. Composite silencing equipment

[0033] As shown in Figures 21, 22 and 23, the present invention provides a composite muffler device based on the Doppler effect, characterized in that: it includes a first rotor module-101 and a first stator module-102, and the first rotor module-101 performs periodic motion relative to the first stator module-102; the first rotor module-101 also includes a universal muffler-20 and a second noise port-10102, wherein the second noise port-10102 is used to generate a Doppler frequency shift effect; the universal muffler-20 moves with the first rotor module-101; the first stator module-102 also includes a third noise port-10102. 203 and the fifth noise port 10205; the second noise port 10102 is respectively connected to the universal silencer 20, the third noise port 10203, and the fifth noise port 10205 along the noise propagation path; the bypass path for noise propagation is from the third noise port 10203 through the second noise port 10102 to the universal silencer 20, and the direct path for noise propagation is from the third noise port 10203 to the fifth noise port 10205; the third noise port 10203 is the noise input port, and the fifth noise port 10205 is the noise output port. The universal silencer 20 includes a micro-perforated plate silencer, and the second noise port 10102 is also a "micro-perforation" of the universal silencer 20. The composite silencer device is a bypass frequency-shift silencer based on receiver-end frequency shift.

[0034] It is understandable that the first rotor 101 that rotates periodically generates mechanical vibration noise and aerodynamic noise, but the frequency spectrum thereof is concentrated. The use of a universal muffler can both reduce and silence the mechanical vibration noise and aerodynamic noise in a targeted manner.

[0035] It is understandable that the noise output port of the composite silencer device can be connected to a universal silencer, and the two together constitute an acoustic system with variable silencer characteristics achieved by changing the speed of periodic mechanical motion.

[0036] It can be understood that the universal muffler includes resistive muffler, reactive muffler and micro-perforated plate type, Helmholtz resonance muffler, micro-perforated plate resonance muffler, and perforated plate resonance muffler. Summarize

[0037] In summary, the present invention provides "two categories and three types" of noise frequency shift devices. The so-called "two categories" are the transmitter frequency shift type and the receiver frequency shift type determined by the direction of the noise transmission path, and the so-called "three types" are the single-stage noise frequency shift device, the serial cascade noise frequency shift device, and the bypass noise frequency shift device determined by the connection topology. The first two are connected to the noise transmission pipeline network in series, and the latter is connected to the noise transmission pipeline network in bypass. By controlling the speed of periodic mechanical motion to change the sound-absorbing characteristics of the acoustic system composed of the frequency shift device and the universal silencer, a new type of silencer with variable sound-absorbing characteristics is obtained in a groundbreaking way. That is, after the material parameters and structural parameters are determined, the sound-absorbing characteristics of the silencer system constituted by it can be changed. Therefore, a new type of silencer method and device is proposed, that is, a frequency shift device, silencer equipment and method based on the Doppler effect, and its implementation method is as follows:

[0038] A noise frequency shift device based on the Doppler effect, characterized in that it comprises a first rotor module and a first stator module, wherein the first rotor module performs periodic motion relative to the first stator module; the first rotor module comprises a first noise port and a second noise port, wherein the second noise port is configured to generate a Doppler frequency shift effect; the first stator module comprises a third noise port, and the second noise port is connected to the first noise port and the third noise port, respectively, along a noise propagation path; the noise propagation path is reversible, with a positive noise propagation path from the first noise port through the second noise port to the third noise port, and a negative noise propagation path from the third noise port through the second noise port to the first noise port; when the noise propagation path is in a positive direction, the device constitutes a transmitting-end noise frequency shift device, with the first noise port serving as a noise input port and the third noise port serving as a noise output port; when the noise propagation path is in a negative direction, the device constitutes a receiving-end noise frequency shift device, with the first noise port serving as a noise output port and the third noise port serving as a noise input port.

[0039] A further improved solution for the noise frequency shifting device based on the Doppler effect is characterized in that: the flow line of the noise medium flowing through the second noise port is not parallel to the rotation axis of the second noise port, which causes the medium momentum to generate a momentum component on a plane perpendicular to the rotation axis, and the momentum component drives the first rotor module to rotate around the rotation axis.

[0040] A further improved solution for the noise frequency shifting device based on the Doppler effect is characterized in that: the first stator module further includes a fourth noise port. When the noise propagation path is in a positive direction, the noise propagates through the fourth noise port to the first noise port, and the fourth noise port serves as a noise input port. When the noise propagation path is in a negative direction, the noise propagates through the first noise port to the fourth noise port, and the fourth noise port serves as a noise output port.

[0041] A further improvement scheme of the noise frequency shift device based on the Doppler effect is characterized in that the frequency shift devices are serially cascaded to form a serial cascade noise frequency shift device, wherein the noise output port of the upper frequency shift device is connected to the noise input port of the lower frequency shift device.

[0042] A further improved solution of the noise frequency shift device based on the Doppler effect is characterized in that the first rotor module of the upper frequency shift device is connected to the first rotor module of the lower frequency shift device to perform periodic motion.

[0043] A further improved solution of the noise frequency shifting device based on the Doppler effect is characterized in that the serial cascade noise frequency shifting device shifts the frequency of the noise to an inaudible frequency band, wherein the inaudible frequency band includes ultrasonic and infrasonic waves.

[0044] A noise bypass frequency shift device based on a receiving end, characterized in that: it includes a first rotor module and a first stator module, and the first rotor module performs periodic motion relative to the first stator module; the first rotor module also includes a first noise port and a second noise port, wherein the second noise port causes the noise to frequency shift; the first stator module includes a third noise port and a fifth noise port; the second noise port is respectively connected to the first noise port, the third noise port, and the fifth noise port on the noise propagation path; the bypass path of noise propagation is from the third noise port through the second noise port to the first noise port, and the straight path of noise propagation is from the third noise port to the fifth noise port; the third noise port is a noise input port, the fifth noise port is a noise output port, and the first noise port is a frequency shift noise output port.

[0045] A further improved solution of the noise bypass frequency shift device based on the receiving end is characterized in that: the first stator module also includes a fourth noise port, and the noise is transmitted to the fourth noise port through the first noise port, and the fourth noise port is a noise output port.

[0046] A composite silencer device based on the Doppler effect, characterized in that: it includes a first rotor module and a first stator module, and the first rotor module performs periodic motion relative to the first stator module; the first rotor module also includes a universal silencer and a second noise port, wherein the second noise port causes the noise to produce a frequency shift, and the universal silencer moves with the first rotor module; the first stator module also includes a third noise port and a fifth noise port; the second noise port is respectively connected to the universal silencer, the third noise port and the fifth noise port on the noise propagation path; the bypass path of noise propagation is from the third noise port through the second noise port to the universal silencer, and the straight path of noise propagation is from the third noise port to the fifth noise port; the third noise port is a noise input port, and the fifth noise port is a noise output port.

[0047] A further improvement scheme for any of the aforementioned noise frequency shift devices based on the Doppler effect is characterized in that it includes a universal muffler connected to the noise output port, and the universal muffler includes a resistive muffler, a reactive muffler and a micro-perforated plate muffler.

[0048] A frequency shift method based on the Doppler effect, characterized by comprising: a rotor module having noise ports, the noise ports comprising a first noise port and a second noise port, the first noise port being connected to the second noise port along a noise propagation path, wherein the first noise port is used to connect to a sound source or output frequency-shifted noise, and the second noise port following the periodic motion of the rotor module relative to a reference frame, causing relative motion between the second noise port and the noise source to induce a Doppler effect, which results in a frequency shift of the transmitting or receiving frequency relative to the reference frame, thereby controlling the frequency shift of the second noise port relative to the reference frame by varying the speed of the periodic motion. The reference frame includes an inertial reference frame and a non-inertial reference frame.

[0049] A further improvement scheme of the frequency shift method based on the Doppler effect is characterized in that: it also includes a stator module, and the rotor module performs periodic motion relative to the stator module; the first stator module includes a third noise port; the second noise port is respectively connected to the first noise port and the third noise port on the noise propagation path; the noise propagation direction is reversible, the positive path of noise propagation is from the first noise port through the second noise port to the third noise port, and the negative path of noise propagation is from the third noise port through the second noise port to the first noise port; when the noise propagation direction is positive, a transmitting end noise frequency shift device is formed, and at this time the second noise port The transmitting frequency is shifted. When the movement direction of the second noise port is the same as the noise propagation direction, the transmitting frequency of the second noise port increases; otherwise, the transmitting frequency of the second noise port decreases. The first noise port serves as a noise input port, and the third noise port serves as a noise output port. When the noise propagation direction is negative, a receiving-end noise frequency shifting device is provided. At this time, the receiving frequency of the second noise port is shifted. When the movement direction of the second noise port is opposite to the noise propagation direction, the receiving frequency of the second noise port increases; otherwise, the receiving frequency of the second noise port decreases. The first noise port serves as a noise output port, and the third noise port serves as a noise input port.

[0050] A further improved solution of the frequency shift method based on the Doppler effect is characterized in that: the stator module further includes a fourth noise port. When the noise propagation path direction is positive, the noise propagates through the fourth noise port to the first noise port, and the fourth noise port serves as the noise input port. When the noise propagation path direction is negative, the noise propagates through the first noise port to the fourth noise port, and the fourth noise port serves as the noise output port.

[0051] A further improvement scheme of the frequency shift method based on the Doppler effect is characterized in that: the implementation devices of any of the aforementioned methods are serially cascaded to form a serial cascade noise frequency shift device, wherein the noise output port of the upper-level frequency shift device is connected to the noise input port of the lower-level frequency shift device.

[0052] A further improvement scheme of the frequency shift method based on the Doppler effect is characterized in that: the serial cascade noise frequency shift device shifts the frequency of the noise to an inaudible frequency band, and the inaudible frequency band includes ultrasonic waves and infrasound waves.

[0053] A further improvement scheme of the frequency shift method based on the Doppler effect is characterized in that the rotor module of the upper frequency shift device is connected to the rotor module of the lower frequency shift device, so that the rotor modules of the upper and lower levels perform periodic motion together. Beneficial effects

[0054] The present invention provides a Doppler effect-based frequency shifting device, muffler equipment, and method, characterized by comprising a rotor module having noise ports, the ports comprising a first port and a second port, the first port connected to the second port along a noise propagation path, the first port being used to connect to a sound source or output frequency-shifted noise. The second port periodically moves with the rotor module relative to a reference frame, causing the relative motion between the second port and the noise source to induce a Doppler effect, resulting in a frequency shift in the transmitted or received frequency relative to the reference frame. The frequency shift of the second port relative to the reference frame, which can be inertial or non-inertial, is controlled by varying the speed of the periodic motion. This device overcomes the technical drawback of conventional muffler technology, which suffers from fixed muffler characteristics due to material properties or structural constraints, and provides a novel muffler with variable muffler characteristics. This invention, following the principles of resistive and reactive mufflers, pioneers a new muffler system that modifies muffler characteristics through mechanical motion. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] FIG1 is a schematic diagram of the appearance of a first rotor module;

[0056] FIG2 is a schematic cross-sectional view of the first rotor module;

[0057] FIG3 is a schematic diagram of the appearance of a single-stage noise frequency shift device;

[0058] FIG4 is a cross-sectional schematic diagram of a single-stage noise frequency shifting device;

[0059] FIG5 is an exploded schematic diagram of a single-stage noise frequency shifting device;

[0060] FIG6 is a schematic diagram of the appearance of a single-stage noise frequency shifting device with a fourth noise port;

[0061] FIG7 is a cross-sectional schematic diagram of a single-stage noise frequency shifting device having a fourth noise port;

[0062] FIG8 is an exploded view of a single-stage noise frequency shifting device with a fourth noise port;

[0063] FIG9 is a schematic diagram of the appearance of a two-stage TT or RR type serial cascade noise frequency shifting device;

[0064] FIG10 is a cross-sectional schematic diagram of a two-stage TT or RR type serial cascade noise frequency shifting device;

[0065] FIG11 is a schematic diagram of the appearance of a two-stage TR type serial cascade noise frequency shift device;

[0066] FIG12 is a cross-sectional schematic diagram of a two-stage TR type serial cascade noise frequency shift device;

[0067] FIG13 is a schematic diagram of the appearance of a coaxial two-stage TR-type serial cascade noise frequency shifting device;

[0068] FIG14 is a cross-sectional schematic diagram of a coaxial two-stage TR-type serial cascade noise frequency shifting device;

[0069] FIG15 is a schematic diagram of the appearance of a noise bypass frequency shift device based on a receiving end;

[0070] FIG16 is a cross-sectional schematic diagram of a noise bypass frequency shifting device based on a receiving end;

[0071] FIG17 is an exploded diagram of a noise bypass frequency shifting device based on a receiving end;

[0072] FIG18 is a schematic diagram of the appearance of a noise bypass frequency shifting device based on a receiving end with a fourth noise port;

[0073] FIG19 is a cross-sectional schematic diagram of a noise bypass frequency shifting device based on a receiving end with a fourth noise port;

[0074] FIG20 is an exploded view of a noise bypass frequency shifting device based on a receiving end with a fourth noise port;

[0075] FIG21 is a schematic diagram of the appearance of a composite silencing device based on the Doppler effect;

[0076] FIG22 is a cross-sectional schematic diagram of a composite silencing device based on the Doppler effect;

[0077] FIG23 is a schematic diagram of an explosion of a composite silencing device based on the Doppler effect;

[0078] FIG24 is a schematic diagram of the appearance of a first rotor module having a second noise port that is not parallel to the rotation axis;

[0079] FIG25 is a cross-sectional view of a first rotor module having a second noise port that is not parallel to the rotation axis; Reference numerals

[0080] Frequency shift device-10;

[0081] First rotor module-101;

[0082] First noise port - 10101;

[0083] Second noise port - 10102;

[0084] First stator module-102;

[0085] The third noise port - 10203;

[0086] Fourth noise port-10204;

[0087] Fifth noise port-10205;

[0088] First tube - 10201;

[0089] Rotation axis - 103;

[0090] Universal muffler equipment-20

[0091] The center axis of the second noise port is -104. DETAILED DESCRIPTION First embodiment

[0092] Specifically, as shown in Figures 3, 4 and 5, the present invention proposes a first embodiment of a single-stage noise frequency shift device based on the Doppler effect, including a first rotor module-101 and a first stator module-102, wherein the first rotor module-101 includes a plurality of second noise ports-10102, and the first stator module-102 includes a third noise port-10203, and the structure of the first tube-10201 is adopted so that the first stator module-102 forms an acoustic cavity distributed along the motion trajectory of the second noise ports-10102, and the acoustic cavity enables the noise propagation path to be interactively connected and interact with the motion trajectory of the second noise ports-10102. Along the tangential direction of the propagation path constrained by the first tube-10201 included in the first stator module-102, the noise propagation direction is parallel to the linear velocity direction of the second noise ports-10102, which maximizes the linear velocity u or v to obtain the optimal Doppler frequency shift effect. One end of the first tube 10201 is connected to the third noise port 10203. When the noise propagation path is positive, the third noise port 10203 is the frequency shift noise output port. Otherwise, when the noise propagation path is negative, the third noise port 10203 is the noise input port.

[0093] Assuming that the angular velocity of the rotating axis-103 is ω, the linear velocity v of the second noise port-10102 is ω=ωr, where r is the vertical distance from the second noise port 10102 to the rotation axis 103. When the noise propagation path is in the positive direction, the noise propagation path is from the first noise port 1001, through the second noise port 10102 to the third noise port 10203, forming a transmitting end noise frequency shift device, and its single-stage frequency shift factor , where c is the speed of sound, u=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, u is positive, otherwise u is negative; when the noise propagation path is negative, the noise propagation path is from the third noise port 10203, through the second noise port -10102 to the first noise port 10101, forming a receiving end noise frequency shift device, and its single-stage frequency shift factor , where c is the speed of sound, v=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, v is negative, otherwise v is positive.

[0094] It can be understood that one of the reference systems of the periodic motion of the first rotor module-101 is the first stator module-102, the acoustic structure of the first tube-10201 makes the noise propagation path one-dimensional, and there is a relative relationship of the same direction and opposite direction between the tangential direction of the noise propagation path and the linear velocity direction of the second noise port-10102.

[0095] The noise frequency shifting device shown in Figures 3, 4 and 5 has certain technical drawbacks or deficiencies in connecting the first noise port 10101 to an external noise transmission pipeline because the first noise port 10101 rotates relative to the first stator module 102 or the reference frame. Therefore, it is necessary to improve the noise frequency shifting device shown in Figures 3, 4 and 5. As shown in Figures 6, 7 and 8, a fourth noise port 10204 is added to the first stator module 102 and connected to the first noise port 10101 to resolve the technical drawbacks or deficiencies. When the noise propagation path is positive, the fourth noise port 10204 is the noise input port. Otherwise, when the noise propagation path is negative, the fourth noise port 10204 is the frequency shift noise output port.

[0096] It can be understood that, when the structural dimensions of the single-stage noise frequency shift device and the universal silencer remain unchanged, the frequency shift noise output port (the fourth noise port 10204 or the third noise port 10203) of the single-stage noise frequency shift device is connected to the universal silencer to form a new type of silencer system with variable silencer characteristics. By controlling the rotational angular velocity ω, the silencer characteristics of the new type of silencer system can be changed. For example, when the rotational angular velocity ω increases u and v, the silencer amplitude-frequency response characteristic curve of the new type of silencer system can be shifted to the low frequency band. Conversely, when the rotational angular velocity ω reduces u and v, the silencer amplitude-frequency response characteristic curve can be shifted to the high frequency band. This realizes a new type of silencer system with variable silencer characteristics, and thus realizes the implementation of the present invention, that is, a technical solution of a frequency shift device, silencer equipment and method based on the Doppler effect.

[0097] On the other hand, because there is an upper limit to the angular velocity ω of the first rotor module-101 rotating around the rotation axis-103, the frequency shift factor of the single-stage noise frequency shift device also has an upper limit of about 8-10 times in engineering applications. Therefore, the single-stage noise frequency shift device has a technical defect that the frequency shift factor is difficult to further increase. Second embodiment

[0098] In order to overcome the technical defects described in the first embodiment, as shown in Figures 9 and 10, the present invention proposes a second embodiment of a serial cascade noise frequency shift device based on the Doppler effect. The technical solution adopted is to serially cascade multiple single-stage noise frequency shift devices into an acoustic system, and the noise frequency shift device at the transmitting end is abbreviated as T, and the noise frequency shift device at the receiving end is abbreviated as R. The combination of the upper and lower stage noise frequency shift devices includes TT type, RR type and TR type.

[0099] As shown in Figures 9 and 10, assuming that the mechanical and acoustic characteristics of the upper and lower noise frequency shift devices are identical, the angular velocity ω1 of the upper stage's rotation axis-10301 and the angular velocity ω2 of the lower stage's rotation axis-10302 are equal, i.e., ω1=ω2. Therefore, the linear velocity v1 of the upper stage's second noise port-1010201 and the linear velocity v2 of the lower stage's second noise port-1010202 are equal, i.e., v1=v2=v ω , where v ω =ωr1, r1 is the vertical distance from the second noise port -1010201 to the rotation axis -10301. When the noise propagation path is in the positive direction, the noise propagation path is from the fourth noise port 1020401 of the previous stage to the third noise port 1020302 of the next stage. The upper and lower stages are both transmitting end noise frequency shift devices and constitute the aforementioned TT type combination. Its two-stage frequency shift factor , where c is the speed of sound, u=vω , and when the linear velocity v ω When the direction is the same as the noise propagation path, u is positive, otherwise u is negative; when the noise propagation path is negative, the noise propagation path is from the third noise port 1020302 of the next stage to the fourth noise port 1020401 of the previous stage. The upper and lower stages are both receiving end noise frequency shift devices and constitute the aforementioned RR type combination. Its two-stage frequency shift factor , where c is the speed of sound, v=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, v is negative, otherwise v is positive.

[0100] As shown in Figures 11 and 12, assuming that the mechanical and acoustic characteristics of the upper and lower noise frequency shift devices are identical, the angular velocity ω1 of the upper stage's rotation axis 10301 and the angular velocity ω2 of the lower stage's rotation axis 10302 are equal, i.e., ω1=ω2. Therefore, the linear velocity v1 of the upper stage's second noise port 1010201 and the linear velocity v2 of the lower stage's second noise port 1010202 are equal, i.e., v1=v2=v ω , where v ω =ωr1, r1 is the vertical distance from the second noise port -1010201 to the rotation axis -10301. When the noise propagation path is in the positive direction, the noise propagation path is from the fourth noise port 1020401 of the previous stage to the fourth noise port 1020402 of the next stage. The upper and lower stages are respectively the transmitting end noise frequency shift device and the receiving end noise frequency shift device, which constitute the aforementioned TR type combination. Its two-stage frequency shift factor , where c is the speed of sound, u=v=v ω , and when the linear velocity v ω When the direction is the same as the noise propagation path, the upper level linear velocity u is positive and the lower level linear velocity v is negative, otherwise u is negative and v is positive; when the noise propagation path is negative, due to the structural and acoustic symmetry, the acoustic frequency shift characteristics of the serial cascade noise frequency shift device are equivalent to or the same as when the noise propagation path is positive.

[0101] It is understandable that when n noise frequency shifting devices are serially cascaded, assuming that the frequency shift factor of the i-th stage is k i , then the frequency shift factor k of the n-stage serial cascade noise frequency shift device is total is the product of multiple frequency shift factors, that is, k total =∏1 n k i where i=1, 2, 3.....n-1, n, the spectrum range of audible sound is [20Hz, 20kHz], when k total When k is greater than 1000, the audible sound frequency is transferred to the ultrasonic frequency band.total When k is less than 1 / 1000, the audible sound frequency is transferred to the infrasound frequency band, making the noise become inaudible sound waves. total When the range is [1, 1000], a universal silencer is connected to the aforementioned noise output port for silencing. Since the noise frequency is increased by frequency shift, the structural volume of the universal silencer can be reduced. More importantly, the silencing characteristics of the acoustic system composed of the frequency shift device and the universal silencer can be changed by controlling the speed of the periodic mechanical motion.

[0102] It can be understood that when the multiple serial cascade frequency shift devices are of TT type, if u=0.5c, it can be seen that the TT-type single-stage frequency shift device can increase the noise frequency by 2 times. Since the range of audible sound is 20Hz to 20kHz, then the 10-stage cascade TT-type single-stage frequency shift device can increase the noise frequency by 1024 times, turning the audible sound into an ultrasonic wave of 20.48kHz-20.48MHz that is inaudible to the human ear, thereby achieving the technical purpose of noise reduction. Therefore, the serial cascade noise frequency shift device can be used independently as a silencer without being combined with a general silencer. It is essentially a silencer of a new system.

[0103] It can be understood that the universal muffler includes resistive muffler, reactive muffler and micro-perforated plate type, Helmholtz resonance muffler, micro-perforated plate resonance muffler, and perforated plate resonance muffler.

[0104] It is understandable that the aforementioned two-stage serial cascade noise frequency shift device shown in Figures 11 and 12 uses independent rotating shafts 10301 and 10302 respectively, which will lead to a complex drive system and is not conducive to the compact and miniaturized design of the muffler structure. In view of this technical deficiency, as shown in Figures 13 and 14, the first rotor module of the upper frequency shift device is connected to the first rotor module of the lower frequency shift device, so that the upper and lower rotor modules use the same rotating shaft 10301 to perform periodic motion together, and the two-stage frequency shift factor is 10301. , where c is the speed of sound, u=v=v ω , where v ω =ωr1, r1 is the vertical distance from the second noise port-1010201 to the rotation axis-10301, and when the linear velocity v ω When the direction is the same as the noise propagation path, u is positive and v is negative, otherwise u is negative and v is positive. Third embodiment

[0105] In engineering applications, the aforementioned single-stage noise frequency shift device and the serial cascade noise frequency shift device are connected to the noise transmission pipeline network in a serial manner. However, there are bypass access application requirements in engineering applications. As shown in Figures 15, 16 and 17, the present invention proposes a third embodiment of a bypass noise frequency shift device based on a receiving end, comprising a first rotor module-101 and a first stator module-102, and the first rotor module-101 performs periodic motion around the rotation axis-103 relative to the first stator module-102; the first rotor module-101 also comprises a first noise port-10101 and a second noise port-10102, wherein the second noise port-10102 is used to cause the noise to produce a Doppler frequency shift effect; the first stator module- 102 includes a third noise port 10203 and a fifth noise port 10205. The second noise port 10102 is connected to the first noise port 10101, the third noise port 10203, and the fifth noise port 10205 along the noise propagation path. The bypass path of noise propagation is from the third noise port 10203 through the second noise port 10102 to the first noise port 10101, and the straight path of noise propagation is from the third noise port 10203 to the fifth noise port 10205. The third noise port 10203 is the noise input port, the fifth noise port 10205 is the noise output port, and the first noise port 10101 is the frequency shift noise output port. The linear velocity of the second noise port 10102 is v, and the frequency shift factor is . , where c is the speed of sound, and when the linear velocity v is opposite to the direction of the noise propagation path, v is a positive value, otherwise v is a negative value.

[0106] It can be understood that, in the bypass noise frequency shifting device shown in Figures 15, 16 and 17, since the first noise port 10101 rotates relative to the first stator module 102 or the reference system, there are certain technical disadvantages or shortcomings in connecting the first noise port 10101 to the external noise transmission pipeline. Therefore, it is necessary to improve the bypass noise frequency shifting device shown in Figures 15, 16 and 17. As shown in Figures 18, 19 and 20, a fourth noise port 10204 is added to the first stator module 102 and connected to the first noise port 10101 to solve the technical disadvantages or shortcomings. When the noise propagation path is positive, the fourth noise port 10204 is the noise input port. Otherwise, when the noise propagation path is negative, the fourth noise port 10204 is the frequency shift noise output port. Fourth embodiment

[0107] As shown in Figures 21, 22 and 23, the present invention proposes a fourth embodiment of a composite silencer device based on the Doppler effect, which is characterized by: comprising a first rotor module-101 and a first stator module-102, and the first rotor module-101 performs periodic motion relative to the first stator module-102; the first rotor module-101 also includes a universal silencer-20 and a second noise port-10102, wherein the second noise port-10102 is used to generate a Doppler frequency shift effect; the universal silencer-20 moves with the first rotor module-101; the first stator module-102 also includes a third noise port -10203 and the fifth noise port-10205; the second noise port-10102 is respectively connected to the universal silencer-20, the third noise port-10203, and the fifth noise port-10205 along the noise propagation path; the bypass path for noise propagation is from the third noise port-10203 through the second noise port-10102 to the universal silencer-20, and the direct path for noise propagation is from the third noise port-10203 to the fifth noise port-10205; the third noise port-10203 is the noise input port, and the fifth noise port-10205 is the noise output port. The universal silencer-20 is a micro-perforated plate silencer, and the second noise port-10102 also serves as the "micro-perforation" of the micro-perforated plate silencer. The composite silencer device is a bypass frequency-shift silencer based on receiver-end frequency shift.

[0108] The universal silencer-20 is a micro-perforated plate resonance silencer, which is formed by processing perforations with a diameter of less than 1 mm on the surface of the first rotor module-101. The perforations also constitute the second noise port-10102, and the interior of the first rotor module-101 is a cavity, which in turn constitutes the cavity behind the micro-perforated plate, thereby forming a micro-perforated plate resonance silencer. From the sound absorption principle, the micro-perforated plate has sufficient sound resistance and a sufficiently low mass acoustic impedance to form a broadband sound absorber.

[0109] The first tube 10201 is arranged in a geometric path around the movement trajectory of the second noise port 10102 (the micro-perforation). On the noise propagation path, the first tube 10201 is respectively connected to the third noise port 10203, the fifth noise port 10205 and the universal muffler 20 (micro-perforated plate resonance muffler).

[0110] When the first rotor module 101 rotates relative to the first stator module 102, relative movement occurs between the universal muffler 20 and the noise source, causing the receiving frequency of the universal muffler 20 to shift. It can be seen from the formula that when the movement direction of v is opposite to the direction of the noise propagation path, v is positive. When v=0.2c, the frequency shift factor k=1.2 can be obtained, which is equivalent to the receiving frequency of the universal sounder-20 being increased to 1.2 times. If the universal sounder-20 is a micro-perforated plate resonance silencer, then the depth structural dimension of the cavity behind the plate can be reduced by 1.2 times, achieving the beneficial effect of significantly reducing the volume of the silencer.

[0111] On the other hand, when the structural dimensions of the universal silencer-20 remain unchanged, the composite silencer based on the Doppler effect provided in this embodiment can change the silencer characteristics of the composite silencer based on the Doppler effect provided in this embodiment by adjusting the rotational angular velocity ω of the rotating shaft-103. For example, when the rotational angular velocity ω increases v, the silencer amplitude-frequency response characteristic curve of the composite silencer based on the Doppler effect provided in this embodiment can be shifted to the low frequency band. Conversely, when the rotational angular velocity ω decreases v or is negative, the silencer amplitude-frequency response characteristic curve can be shifted to the high frequency band, thereby realizing a new type of silencer with variable silencer characteristics, which can realize the implementation of the present invention, that is, a technical solution of a frequency shift device, silencer equipment and method based on the Doppler effect.

[0112] It can be understood that the first rotor-101 in the rotating periodic motion generates mechanical vibration noise and aerodynamic noise, but its spectrum is concentrated. The use of a universal silencer can both reduce and silence the mechanical vibration noise and aerodynamic noise in a targeted manner. In this embodiment, the universal silencer-20 is a micro-perforated plate resonance silencer, but the universal silencer-20 includes but is not limited to the micro-perforated plate resonance silencer used in this embodiment, and also includes resistive silencers and impedance silencers such as Helmholtz resonance silencers.

[0113] It can be understood that in order to further eliminate the residual noise output by the fifth noise port-10205, the fifth noise port-10205 can be further connected to a universal muffler, and the two together constitute a new type of muffler acoustic system with variable muffler characteristics achieved by changing the speed of periodic mechanical motion.

[0114] In summary, the present invention provides "two categories and three types" of noise frequency shift devices. The so-called "two categories" are the transmitter frequency shift type and the receiver frequency shift type determined by the direction of the noise transmission path, and the so-called "three types" are the single-stage noise frequency shift device, the serial cascade noise frequency shift device, and the bypass noise frequency shift device determined by the connection topology. The first two are connected to the noise transmission pipeline network in series, and the latter is connected to the noise transmission pipeline network in bypass. By controlling the speed of periodic mechanical motion to change the sound-absorbing characteristics of the acoustic system composed of the frequency shift device and the universal silencer, a new type of silencer with variable sound-absorbing characteristics is obtained in a groundbreaking way. That is, after the material parameters and structural parameters are determined, the sound-absorbing characteristics of the new type of silencer system constituted by it can be changed. Therefore, a new type of silencer method and device is proposed, that is, a frequency shift device, silencer equipment and method based on the Doppler effect. Industrial Applicability

[0115] The present application provides a novel silencer device and method with variable silencer characteristics, which can be used in application fields where high-speed mechanical rotation occurs and generates high noise pollution, such as power tools such as hand drills, and household appliances such as hair dryers. High-speed mechanical rotation is used to increase the silencer volume of a general silencer or silencer method, and the structural volume and weight of the general silencer are reduced, thereby achieving multiple beneficial effects.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A noise frequency shift device based on the Doppler effect, characterized in that: It comprises a first rotor module and a first stator module, and the first rotor module performs periodic motion relative to the first stator module; the first rotor module comprises a first noise port and a second noise port, wherein the second noise port is used to generate a Doppler frequency shift effect; the first stator module comprises a third noise port; the second noise port is respectively connected to the first noise port and the third noise port on a noise propagation path; the direction of the noise propagation path is reversible, the positive path of noise propagation is from the first noise port through the second noise port to the third noise port, and the negative path of noise propagation is from the third noise port through the second noise port to the first noise port; When the direction of the noise propagation path is forward, a transmitting end noise frequency shifting device is formed, the first noise port is a noise input port, and the third noise port is a noise output port; When the direction of the noise propagation path is negative, a noise frequency shift device at the receiving end is formed, the first noise port is a noise output port, and the third noise port is a noise input port.

2. The noise frequency shift device based on the Doppler effect according to claim 1, characterized in that: The flow path of the noise medium flowing through the second noise port is not parallel to the rotation axis of the second noise port, which makes the medium momentum generate a momentum component on a plane perpendicular to the rotation axis, and the momentum component drives the first rotor module to rotate around the rotation axis.

3. The noise frequency shift device based on the Doppler effect according to claim 1, characterized in that: The first stator module further includes a fourth noise port. When the noise propagation path is in a positive direction, the noise propagates to the first noise port through the fourth noise port. The fourth noise port is a noise input port. When the direction of the noise propagation path is negative, the noise propagates through the first noise port to the fourth noise port, and the fourth noise port is the noise output port.

4. The noise frequency shift device based on the Doppler effect according to any one of claims 1 to 3, characterized in that: The frequency shift devices described in series cascade constitute a series cascade noise frequency shift device, wherein the noise output port of the upper frequency shift device is connected to the noise input port of the lower frequency shift device.

5. The noise frequency shift device based on the Doppler effect according to claim 4, characterized in that: The first rotor module of the upper-stage frequency shift device is connected to the first rotor module of the lower-stage frequency shift device for periodic motion.

6. The noise frequency shift device based on the Doppler effect according to claim 4, characterized in that: The serial cascade noise frequency shifting device shifts the frequency of the noise to an inaudible frequency band, and the inaudible frequency band includes ultrasonic waves and infrasonic waves.

7. A noise bypass frequency shift device based on a receiving end, characterized in that: It includes a first rotor module and a first stator module, and the first rotor module performs periodic motion relative to the first stator module; the first rotor module also includes a first noise port and a second noise port, wherein the second noise port causes the noise to generate frequency shift; the first stator module includes a third noise port and a fifth noise port; the second noise port is respectively connected to the first noise port, the third noise port and the fifth noise port on the noise propagation path; the bypass path of noise propagation is from the third noise port through the second noise port to the first noise port, and the straight path of noise propagation is from the third noise port to the fifth noise port; the third noise port is a noise input port, the fifth noise port is a noise output port, and the first noise port is a frequency shift noise output port.

8. The noise bypass frequency shift device based on the receiving end according to claim 7, characterized in that: The first stator module further includes a fourth noise port, and noise is transmitted to the fourth noise port through the first noise port. The fourth noise port is a noise output port.

9. A composite silencing device based on the Doppler effect, characterized in that: It includes a first rotor module and a first stator module, and the first rotor module performs periodic motion relative to the first stator module; the first rotor module also includes a universal muffler and a second noise port, wherein the second noise port causes the noise to produce frequency shift, and the universal muffler moves with the first rotor module; the first stator module also includes a third noise port and a fifth noise port; the second noise port is respectively connected to the universal muffler, the third noise port and the fifth noise port on the noise propagation path; the bypass path of noise propagation is from the third noise port through the second noise port to the universal muffler, and the straight path of noise propagation is from the third noise port to the fifth noise port; the third noise port is a noise input port, and the fifth noise port is a noise output port.

10. The noise frequency shift device based on the Doppler effect according to any one of claims 1 to 9, characterized in that: A universal muffler is connected to the noise output port, and the universal muffler includes a resistive muffler, a reactive muffler and a micro-perforated plate muffler.

11. A frequency shift method based on the Doppler effect, characterized in that: The invention comprises a rotor module having a noise port, wherein the noise port comprises a first noise port and a second noise port, wherein the first noise port is connected to the second noise port on a noise propagation path, wherein the first noise port is used to connect a sound source or output frequency shift noise, and the second noise port follows the rotor module to perform periodic motion relative to a reference system, so that the second noise port and the noise source move relative to each other and a Doppler effect occurs, which causes a frequency shift in a transmitting or receiving frequency relative to the reference system, thereby controlling the frequency shift of the second noise port relative to the reference system by changing the speed of the periodic motion, wherein the reference system comprises an inertial reference system and a non-inertial reference system.

12. The frequency shift method based on the Doppler effect according to claim 11, characterized in that: It also includes a stator module, and the rotor module performs periodic motion relative to the stator module; the first stator module includes a third noise port; the second noise port is respectively connected to the first noise port and the third noise port on the noise propagation path; the noise propagation direction is reversible, the positive path of noise propagation is from the first noise port through the second noise port to the third noise port, and the negative path of noise propagation is from the third noise port through the second noise port to the first noise port; When the noise propagation direction is positive, a noise frequency shift device at the transmitting end is formed, and the transmitting frequency of the second noise port is frequency shifted. When the movement direction of the second noise port is the same as the noise propagation direction, the transmitting frequency of the second noise port is increased, otherwise, the transmitting frequency of the second noise port is reduced. The first noise port is the noise input port, and the third noise port is the noise output port. When the noise propagation direction is negative, a noise frequency shift device at the receiving end is formed, and the receiving frequency of the second noise port is frequency shifted. When the movement direction of the second noise port is opposite to the noise propagation direction, the receiving frequency of the second noise port is increased, otherwise, the receiving frequency of the second noise port is reduced. The first noise port is the noise output port, and the third noise port is the noise input port.

13. The frequency shift method based on the Doppler effect according to claim 12, characterized in that: The stator module further includes a fourth noise port. When the noise propagation path is in a forward direction, the noise propagates to the first noise port through the fourth noise port. The fourth noise port is a noise input port. When the direction of the noise propagation path is negative, the noise propagates through the first noise port to the fourth noise port, and the fourth noise port is a noise output port.

14. The frequency shift method based on the Doppler effect according to any one of claims 11 to 13, characterized in that: The device for implementing the method described in any one of claims 11 to 13 is serially cascaded to form a serially cascaded noise frequency shift device, wherein the noise output port of the upper-stage frequency shift device is connected to the noise input port of the lower-stage frequency shift device.

15. The frequency shift method based on the Doppler effect according to claim 14, characterized in that: The serial cascade noise frequency shifting device shifts the frequency of the noise to an inaudible frequency band, and the inaudible frequency band includes ultrasonic waves and infrasonic waves.

16. The frequency shift method based on Doppler effect according to claim 14, characterized in that: The rotor module of the upper frequency shift device is connected to the rotor module of the lower frequency shift device, so that the rotor modules of the upper and lower levels perform periodic motion together.

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