459results about How to "Achieve noise reduction effect" patented technology

The invention discloses an expansive type silencer and a fresh air system and relates to the technical field of indoor ventilating and exhausting equipment. The expansive type silencer and the fresh air system are invented for solving the problem that an existing expansive type silencer cannot be used for achieving broadband sound eliminating. The expansive type silencer comprises an expansion pipe. Connecting nozzles are arranged at the two ends of the expansion pipe. The area of the sections of the connecting nozzles is smaller than the area of the section of the expansion pipe. The expansion pipe comprises a fixed pipe section and a telescopic pipe section. The end, close to the fixed pipe section, of the telescopic pipe section is matched and connected with the fixed pipe section in a sleeving manner and can slide in the length direction of the fixed pipe section to adjust the length of the expansion pipe. The expansive type silencer is used for the fresh air system.

The invention discloses a range hood with an active noise reduction function. The range hood comprises a range hood main body and an active noise reduction device fixedly arranged on the range hood main body, wherein the active noise reduction device is provided with a first noise sensor, a loudspeaker, a second noise sensor and an active noise reduction system. Compared with a range hood with a traditional passive noise reduction mode which can only be used for reducing noise above 500 Hz although the leakproofness and material are good, the range hood with the active noise reduction functioncan actively generate reverse sound waves with the same frequency as the outside noise through the active noise reduction device to neutralize the noise so that the noise reduction effect can be achieved. The range hood with the active noise reduction function can enable oil smoke particles to not pass through an air draft assembly, an oil film cannot be attached to a wind wheel in the air draftassembly even with the increase of the use time, load-bearing work is not needed, and therefore low-noise work can be kept all the time. The range hood with the active noise reduction function has theadvantage that the noise of different frequencies can be greatly reduced when the range hood works.

The invention relates to bearing lubricating grease comprising the following components of: (a) a compound thickening agent formed by lithium 12-hydroxystearate soap, lithium binary acid soap and lithium borate, (b) an additive, and (c) base oil, wherein the compound thickening agent is formed by soapnifying 12-hydroxystearic acid, binary acid and boric acid with lithium hydroxide; and the additive amount of the boric acid is 1-5 parts by weight while the weight of the base oil is 100 parts by weight, wherein the additive is one or combination of at least two of an antioxidant, an antirusting agent, an anti-wear reagent at extreme pressure and a metal passivator. The dropping point temperature of the bearing lubricating grease provided by the invention is more than or equal to 300 DEG C, and the bearing lubricating grease provided by the invention does not collapse or fade and has the characteristics of long service life, silence and high temperature resistance.

The invention discloses a straw crushing and packaging machine. The straw crushing and packaging machine comprises a base, wherein a controller is arranged in the base; a storage groove, a crushing box, a support seat and a packaging box are sequentially arranged on the upper surface of the base from the left to right; a conveying mechanism is arranged in the storage groove; a conveying belt on the conveying mechanism is connected with a charge port arranged in the left side of the top of the crushing box; a seat is arranged at the middle part of the right side of the crushing box; an oscillator is arranged in the seat, and a metal tube is arranged at one end of the oscillator; the left end of the metal tube sequentially penetrates through the seat and the crushing box, and extends into the crushing box; and the left end of the metal tube is connected with a filter screen plate which is arranged at the middle part of the inner cavity of the crushing box. The straw crushing and packaging machine is convenient to operate, achieves a uniform crushing effect, and increases the packaging efficiency; blades on knife holders are used for cutting and crushing straw, the crushed straw is filtered through the filter screen plate, and large straw continues to be crushed, thus a thorough crushing effect for straw is achieved.

The invention provides a method for reducing noise of an earphone and a mobile terminal. The method includes the steps of obtaining ambient noise signals, generating first audio signals opposite in phase to the ambient noise signals based on the ambient noise signals, obtaining second audio signals which are about to be sent to the earphone connected with the mobile terminal, generating target audio signals by superposing the first audio signals with the second audio signals, and sending the target audio signals to the earphone for playing. No extra special hardware is needed to reach good noise reduction effect, and cost remains relatively low. Popularization is facilitated and user demands can be satisfied.

The invention relates to a rolling bearing fault diagnosis method based on dual-tree complex wavelet pack manifold domain noise reduction. The rolling bearing fault diagnosis method based on the dual-tree complex wavelet pack manifold domain noise reduction comprises steps of using an accelerated speed sensor to collect a vibration signal of the rolling bearing, performing dual-tree complex wavelet pack decomposition on the vibration signal, maintaining wavelet pack coefficients of first two nodes, performing threshold noise reduction on wavelet coefficients of the rest nodes, performing single branch reconstruction on the wavelet pack coefficient of each node to perform a high dimensional signal space, using a t distribution random neighbor embedding method to extract low a dimensional manifold, performing inverse reconstruction on the low-dimensional manifold to obtain a high-dimensional space main manifold, obtaining a signal after noise reduction, performing Hilbert envelope demodulation on the signal after noise reduction to obtain an envelope frequency spectrum of the vibration signal, and realizing fault diagnosis of the rolling bearing according to an inner ring fault characteristic frequency and an outer ring fault characteristic frequency of the rolling bearing, a rolling body fault characteristic frequency and a retainer fault characteristic frequency.

The invention belongs to the field of pipes, relates to an enhanced drainage pipe and mainly relates to a superstrong-muting PE (polyethylene) core layer micro-foamed drainage pipe which is suitable for wastewater discharging, engineering transforming projects and home decoration of villa communities, high-rise residential communities, high-grade residential apartment communities and the like and industrial building fields like water discharging, sewage discharging, waste discharging and the like of industrial enterprises. The superstrong-muting PE composite drainage pipe is a multilayer composite body formed by a high-density polyethylene resin inner layer, a middle PE micro-foamed layer and a high-density polyethylene resin outer layer, the thickness ratio of the inner layer, the middle layer and the outer layer is 1:4:1, and the PE micro-foamed layer is composed of regenerated polyethylene resin powder, inorganic filler or organic filler, natural fibers, a cross-linking agent, a coupling agent, a lubricating agent, a foaming agent and an antioxidant. The superstrong-muting PE core layer micro-foamed drainage pipe has excellent denoising and muting performance, superstrong resistance to chemical corrosion and good impact resistance.

The invention provides a speech enhancement method and device, and the voice enhancement method includes the steps: receiving to-be-enhanced speech data; separating at least one speech stream from theto-be-enhanced speech data based on a long-term and short-term memory neural network; recognizing a target speech stream corresponding to the predetermined speech from at least one speech stream based on a time delay neural network; enhancing the target speech stream; and outputting the enhanced target voice stream. The speech enhancement method and device separate the enhanced speech data by thelong-term and short-term memory neural network, and then recognizes the target speech stream from the separated result through the time delay neural network, and then only enhances the target speechstream, so that the target speech is clear, thereby achieving the effect of noise reduction and effectively improving the user experience.

The invention discloses a multi-stage denoiser and a valve with the same. The multi-stage denoiser comprises a hollow denoising cylinder and at least two stages of denoising covers. The denoising covers are arranged in the hollow denoising cylinder in the extension direction of the hollow denoising cylinder. Each stage of denoising cover is provided with a fluid cavity and a fluid inlet formed in the head portion of the fluid cavity. The wall of the fluid cavity of each stage of denoising cover is provided with a plurality of through holes. The fluid inlet of the fluid cavity of the rear stage of denoising cover corresponds to the tail portion of the front stage of denoising cover and forms a buffer cavity together with the tail portion of the front stage of denoising cover. The valve comprises a valve body and an outflow passageway of fluid. The outlet of the outflow passageway is fixedly connected with the denoiser in the axial direction. By arranging the multiple stages of denoising covers, the denoising efficiency is improved, the denoising effect is achieved through the frequency shift effect of small hole spraying, and the fluid flow speed is uniform through the buffer cavity. The vibration caused by fluid impact to the denoiser is reduced in the medium flowing process, and therefore the stability of the product is improved, and the overall service life of the denoiser is prolonged.

The invention provides a silicon microphone and a packaging structure of a product applying same, wherein the silicon microphone comprises a shell and a circuit board which form the external packaging structure of the silicon microphone, an MEMS (Micro-electromechanical Systems) chip is arranged on the surface of the circuit board inside the packaging structure, sound holes used for receiving external sound signals are arranged in the packaging structure, and the surface of the external periphery of the sound holes is provided with a deep-color coating. The invention can realize good light and noise reducing effects only by a manner that the deep-color coating is arranged around the sound holes in the external surface of the silicon microphone, is simple to design and easy to realize, can not increase the production cost and the size of products, and can not affect the picking-up effect of the product.

The invention discloses a voice recognition method and system based on incremental word graph re-scoring. The method comprises the steps that: a to-be-recognized voice signal is obtained and acousticfeatures are extracted; a likelihood probability corresponding to the acoustic features is calculated by using a trained acoustic model; a decoder constructs a corresponding decoding network, obtainsa word graph of a state level from the decoding network and obtains a word graph of a word level by updating the word graph and determining the word graph; state-level word graphs of remaining decoding networks are determined, and the determined state-level word graphs are combined with the obtained word-level word graphs to generate a decoded word graph; a target word graph is obtained through afinite-state transcriber merging algorithm according to a re-scoring language model obtained through one-time decoded word graph and small corpus training; and an optimal cost path word graph of the target word graph is obtained, then a corresponding word sequence is obtained, and the word sequence is taken as a final recognition result. According to the invention, the calculation amount of determination after the decoding of a common decoder is finished is reduced, and the decoding speed is accelerated; the word error rate of speech recognition in a specific scene is reduced, and the accuracyis improved.

The embodiment of the invention discloses a flow guiding ring structure, an axial flow fan and an air conditioner, relates to the denoising field and is used for lowering the pneumatic noise of the axial flow fan in the using process on the premise that the air outflow amount of the fan is guaranteed. The flow guiding ring structure comprises a ring body; the ring body comprises a closed cavity and a through hole; the minimum diameter position of the ring body is provided with open holes; the cavity is communicated with the through hole through the open holes; and fluid in the through hole can enter the cavity through the open holes. Due to the above technical scheme, on the premise that the Venturi tube effect of the flow guiding ring structure is guaranteed, the open structure is added on the surface, the turbulent energy of blade top airflow is transmitted out of a fan area in the radial direction, and therefore the denoising purpose is achieved.

The invention discloses a method and system for reconstructing incoherent motion magnetic resonance imaging parameters in voxels. The method comprises the following steps: setting a parameter D, a parameter f, a parameter D * and a parameter S (0) in a geometric figure generated in a simulation area, and judging whether the total area of all geometric figures covers the simulation area or not; ifso, generating a D parameter graph, an f parameter graph, a D * parameter graph and an S (0) parameter graph; generating a magnetic resonance diffusion weighted image corresponding to each b value, and training the neural network model to obtain a trained neural network model; and performing Fourier transform and normalization processing on the k-space data, and inputting the normalized magnetic resonance diffusion weighted image into the trained neural network model to obtain a reconstructed IVIM parameter image. By adopting the method and the system provided by the invention, the problem that the reconstruction result presents granular sensation due to point-by-point fitting is solved, the image is smoother, the influence of the small b value on the IVIM double-exponential model is considered, and the reconstruction effect is improved.

The invention relates to an oil tank for an oil immersion type transformer, which is used for lowering noise of the oil immersion type transformer and comprises an oil tank body. A layer of tank wall structure is arranged at the outer side of the oil tank body, and a preset air gap is arranged between the tank wall structure and the oil tank body. Flame-retardant and sound-absorbing materials] are lined in the air gap. The tank wall structure and the oil tank body are fixedly connected with a radiator pipe of the oil immersion type transformer in an electric welding way. The invention achieves the effect of noise reduction by improving the structure of the oil tank, has simple structure, convenient processing, favorable concealment and favorable practicability, and can efficiently reduce the noise generated in operation of the transformer, thereby the noise pollution brought by the environment is improved.

The invention discloses a reducing flexible connector for a ship. The reducing flexible connector comprises a large flange and a small flange. A fixing nut is welded and fixed to the outer surface ofthe inner side of the upper top end of the large flange, an anti-torque rubber bar is installed at the outer top end of the fixing nut, a telescopic rubber bag is installed in the center position of the anti-torque rubber bar, a reducing rubber pipe is installed in the center position of the large flange, an inner ring is installed in the center position inside the small flange, a gasket is installed on the outer surface of the inner ring, an aligning spherical surface is installed on the outer surface of the gasket, cylindrical rollers are in rolling connection with the center position of thealigning spherical surface at equal intervals, an outer ring is installed on the outer surface of the aligning spherical surface, a through hole is cut in the center position of the reducing rubber pipe, a plurality of damping air bags are cut inside the reducing rubber pipe, and the upper and lower top ends of the damping air bags are provided with inflation inlets. The reducing flexible connector for the ship is used for a ship system, reduces nose and vibration, and is convenient to install, flexible to use and convenient to maintain.

The invention discloses a roadblock cone with a reset alarm function for ball training. The roadblock cone comprises a roadblock hammer, an anti-falling base, an audible and visual alarm, a limiting plate and a slideway, a reset part is arranged at the bottom of the roadblock hammer; an alarm part is arranged above the reset part; the roadblock hammer is conical; an anti-falling base is integrallyarranged at the bottom of the roadblock hammer; the roadblock hammer is communicated with the interior of the anti-falling base; an arc-shaped anti-falling base and a balancing weight are arranged; the barricade hammer is light in top and heavy in bottom; when the barricade hammer collides with a ball, the barricade hammer rotates; a tumbler principle is used, a moment is generated between the gravity of the roadblock hammer and a landing point; the roadblock hammer shakes and gradually resets, carrying is facilitated, meanwhile, high falling resistance is achieved, and when the roadblock hammer shakes, a movable ball rolls to the switch in the sliding way along with the inclination angle of the roadblock hammer, so that the movable ball triggers the switch, and then the audible and visual alarm gives out effective early warning in ball training.

The invention discloses a noise-reducing plate cutting machine, comprising: a workbench, a support frame, a slide plate, a driving mechanism, a cutting mechanism, a clamping piece and a noise-reducing plate; The upper surface of the upper surface of the groove is located on both sides of the groove, and the clamping parts are symmetrically arranged respectively, and the opposite sides of the workbench are respectively provided with support frames that can slide along the length direction of the workbench, and there is also a horizontal set between the two support frames. Skateboard, the driving mechanism is slidably arranged on the sliding plate, the lower end of the driving mechanism is connected with the cutting mechanism through a telescopic column; the upper surface of the workbench is located on both sides of the groove and at least two noise-reducing boards are installed vertically to reduce noise. A plurality of sound-absorbing holes are respectively arranged on the side of the plate facing the groove, and the sound-absorbing holes are filled with sound-absorbing materials. The noise-reducing plate cutting machine overcomes the problem that the plate cutting machine in the prior art does not have corresponding noise-reducing treatment, resulting in serious pollution to the working environment caused by noise.

The invention discloses a voice recognition method and system based on a deep neural network acoustic model. The method comprises steps of carrying out the sliding windowing preprocessing operation of a to-be-recognized voice, and extracting acoustic features; constructing and training a deep neural network acoustic model; calculating a likelihood probability corresponding to the extracted acoustic features by using the deep neural network acoustic model; constructing a static decoding graph, a decoder constructing a directed acyclic graph containing all recognition results as a decoding network through the static decoding graph and the likelihood probability on the basis of a viterbi algorithm of dynamic programming, and a word graph of the state level being obtained from the decoding network and being determined to obtain the word graph of the word level; and obtaining an optimal cost path word graph of the word-level word graph, obtaining a word sequence corresponding to an optimal state sequence of the word graph, taking the word sequence as a final recognition result, and completing voice recognition. According to the method, gradient dispersion and gradient explosion caused by a complex structure network model can be solved, the word error rate is reduced while the decoding speed is ensured, and recognition accuracy is improved.

The invention relates to a noise-reducing polyethylene composite material for a drainage pipeline of a building and a preparation method thereof, belonging to the technical field of inorganic powder modified high-molecular polymers. The material comprises the following raw materials in parts by weight: 30-50 parts of polyethylene, 0.01-0.02 part of a peroxide initiator, 0.5-1 part of vinyl unsaturated silane, 50-60 parts of barium sulfate, 1-3 parts of a dispersant, 3-5 parts of titanium dioxide, 0.2-0.5 part of an antioxidant and 1-3 parts of carbon black. The material provided by the invention effectively solves the problem that existing drainage pipeline of the building is noisy and poor in high temperature resistance and chemical corrosion resistance. Raw materials are input to a high speed mixer to be mixed firstly, and then pelleted through a twin-screw extruder to obtain the composite material. The composite material provided by the invention has the advantages of mute-resistant effect, chemical corrosion resistance, heat resistance and shock resistance of a common tubular product, simple processing process, low cost and suitability of preparing the drainage pipeline of the building.

The invention discloses a water direct-cooling double-effect condenser which is externally hung a back plate of a refrigerator box body and comprises a first condensation pipe, a second condensation pipe and a condensation water tank, wherein the first condensation pipe is immersed into liquid in the condensation water tank; and the first condensation pipe and the second condensation pipe are connected in series. According to the water direct-cooling double-effect condenser and the refrigerator, the characteristic that the specific heat ratio of water is greater than that of air is utilized and the energy-saving effect is achieved by improving the heat exchanging efficiency of the condenser, improving condensation and heat radiation time and shortening condensation and balancing time by the condensation water tank. Furthermore, an air flow sound of a system can be reduced and the noise-reducing effect is achieved. The water direct-cooling double-effect condenser has an obvious energy-saving effect and the whole machine of the condenser can save more than 20% of energy.

The purpose of this invention is to achieve vibration-dependent noise reduction by the use of a microphone to pick up an audio signal and a vibration sensor. The microphone apparatus according to a preferred embodiment of the present invention is one having one or more microphone, one or more sensor, noise extraction means for extracting the noise bandwidth section from the output signal of the sensor, an adaptive filter coordinated with the microphone for receiving the output signal of the noise extraction means as the reference input signal, and an adder for subtracting the output signal of the adaptive filter from the output signal of the microphone, wherein the vibration detection directions of the microphone and the sensor match, and so do the output polarities of the vibration signal.

The invention relates to a Pu'er tea pressing machine and a tea pressing method. The tea pressing steam-pressure machine comprises a portal frame, a cylinder, a non-return valve, a silencer, a tea pressing panel, a buffer pane, an adjustable die, a stress disc and a hand-operated switch. The pressing steam-pressure machine has the characteristics of fast, simple, convenient and normative operation, needing of no experience technologies, reduction of a traditional tea stone mill pressing operation, reduction of the production processing time, and reduction of the resource consumption, and a molded tea obtained after the pressing in the invention has the characteristics of normativeness, standard property, low loss and high qualified rate, so the pressing steam-pressure machine has the advantages of reduction and avoiding of human processing errors, productivity improvement, labor cost saving, and improvement of the unit time production efficiency.

The embodiment of the invention discloses an unmanned aerial vehicle which comprises a body, a noise collecting device and a control module, wherein the body is provided with at least one connecting arm extending outwards, a shell is arranged on one end, extending outwards, of each connecting arm, a first motor, the noise collecting device and an acoustic wave output device are integrated in the shell, a first rotor wing connected with the first motor is arranged at the upper part of the shell, and the control module is integrated in the body; the noise collecting device is used for collecting noise generated in flying of the unmanned aerial vehicle and sending the noise to the control module; and the control module is used for analyzing the noise, obtaining a reverse acoustic wave which is the same in frequency, same in amplitude and reverse in phase position with the noise, and sending the reverse acoustic wave via the acoustic wave output device. According to the embodiment of the invention, the noise reducing effect of the unmanned aerial vehicle can be improved, and the cost of the unmanned aerial vehicle can be saved.

The invention discloses a sound-absorption and waterproof attapulgite board and a preparation method, which belong to the technical field of attapulgite. The sound-absorption and waterproof attapulgite board comprises an abrasion-resistance and waterproof layer, a rubber buffer layer, a sound absorption layer, a board body and a waterproof protection layer in sequence from top to bottom, wherein the board body is prepared by taking attapulgite as a basic material; the sound absorption layer comprises an elastic layer and sound absorption fillers; a plurality of small holes are formed in the elastic layer and are filled with the sound absorption fillers; the sound absorption fillers are prepared by taking attapulgite as a basic material; the sound absorption layer is connected with the board body by adhesive; the sound absorption layer is connected with the rubber buffer layer by adhesive. The sound-absorption and waterproof attapulgite board has comparatively good sound-absorption, sound-insulation and waterproof effects and has the comparatively good characteristics of stable performance, high strength and good weather resistance; in addition, the preparation method has the characteristics of being simple and being convenient in operation and low in manufacturing cost, so that the current market requirement is met, and the application value is comparatively good.

The invention discloses a resonant labyrinth silencing method which comprises a resistive labyrinth silencing method, an expanded resistance silencing method and a resonant resistance silencing method. A resonant labyrinth silencing combined apparatus comprises two parts, namely a noise spectrum testing system (101) and a resonant labyrinth silencing device (102), wherein the noise spectrum testing system (101) comprises a noise source (50), a sound level meter (51), a high-speed data acquisition card NI (52), a computer (53), a noise time-domain figure (54) and a noise frequency-domain figure (55); and the resonant labyrinth silencing device (102) comprises a first expansion chamber (2), a second expansion chamber (3), a third expansion chamber (4), a first cylindrical resonant chamber (5), a second cylindrical resonant chamber (6), a third cylindrical resonant chamber (7), and the like. According to the silencing method and the apparatus disclosed by the invention, resistance sound absorption is performed by utilizing the three expansion chambers and the three resonant chambers, and resistive sound absorption is performed by utilizing a porous sound absorbing material, so that the silencing effect is achieved.

The invention discloses an audio processing method and device and a storage medium, and belongs to the technical field of audio processing. The method comprises the steps: obtaining the fundamental frequency information, the spectral envelope and the excitation signal phase of a first audio signal to be processed; obtaining a target periodic signal based on the fundamental frequency information, wherein the peak of the target periodic signal is located at the multiplication of the fundamental frequency indicated by the fundamental frequency information; combining the target periodic signal with the excitation signal phase so as to obtain the target excitation signal; and synthesizing the target excitation signal with the spectral envelope so as to obtain a second audio signal. The pure second audio is regenerated based on the periodic characteristic of the first audio so as to achieve the noise reduction effect.

The invention discloses an SCR after-treatment packaging structure for a diesel engine. The SCR after-treatment packaging structure for the diesel engine comprises an injection connecting pipe, a mixer, a silencer and a urea injector installation seat. The mixer is arranged in the injection connecting pipe. The urea injector installation seat is arranged on the injection connecting pipe. The silencer is installed at the end, with the mixer, of the injection connecting pipe. The mixer, the silencer and the like are integrally designed and the installation position of the mixer is located at an intersection of the center line of the urea injector installation seat and the injection connecting pipe. In the direction of the center line of the injection connecting pipe, multiple blades of the mixer are distributed on the left side and the right side, the angle of each blade is 60 degrees, and the blades are welded into the injection connecting pipe. By the adoption of the SCR after-treatment packaging structure for the diesel engine, the problem that a urea aqueous solution is crystallized in a vent pipe of a selective catalytic reduction (SCR) after-treatment system can be solved.

The invention discloses an air inlet silencer for a local ventilator, and mainly solves such technical problems as bigger weight, high noise and low efficiency of a traditional air inlet silencer. The air inlet silencer for the local ventilator is characterized by comprising a current collector and a silencer body; the current collector is a conical cylinder type structure; the silencer body takes the shape of a straight cylinder; the bigger-diameter end of the current collector is mutually matched and fixedly connected with the silencer body; the current collector comprises a current collecting cylinder (8), a first support (9), a first conical cylinder (10) and a plastic uptake guide cap (11); the silencer body comprises a first outer cylinder (12), a first inner cylinder (17), a second outer cylinder (19) and a first conical reflection plate (16); the first outer cylinder (12) and the first inner cylinder (17) are coaxially mounted; and the first outer cylinder (12) and the second outer cylinder (19) are fixedly connected through a first arc reflection plate (18). The air inlet silencer is mainly used for a ventilator air inlet, and realizes such performances as silence, sound insulation through reflection and vibration reduction.

The invention relates to a volute of a centrifugal fan. The volute comprises a front cover plate, a rear cover plate and an annular middle ring wall. The front cover plate and the rear cover plate are connected together through a continuous smooth transition warp surface of the middle ring wall. The front cover plate and the rear cover plate are provided with front air inlet holes and rear air inlet holes respectively. The projection of the circle centers of the front air inlet holes in the plane of the rear cover plate coincides with the circle centers of the rear air inlet holes. The volute is characterized in that the edge outline of the front side of the middle ring wall is formed by connecting a straight line AB, a straight line BC, a curve CD, a curve DE, a curve EF, a curve FG, a curve GH, a curve HI, a curve IJ, a curve JK, a curve KL, a curve LM, a straight line MN, a straight line NO and a straight line OP which are sequentially in smooth transition, and the edge outline of the rear side of the middle ring wall is the same as the edge outline of the front side. Compared with the prior art, by means of the special design on the middle ring wall of the volute, the structure is more reasonable, the internal smoothness of the volute is improved, and the static pressure is increased; and meanwhile, the noise lowering effect is achieved, and the volute is suitable for the small size.

The invention provides a method for optimizing exhaust back pressure of an internal combustion engine. The method comprises arranging a damping component in an exhaust passage of the internal combustion engine, and enabling tail gas exhausted out of the internal combustion engine to pass the damping component; and enabling the tail gas to be cooled before passing the damping component, or enabling the tail gas to be cooled while passing the damping component. Through the method, the internal combustion engine has the high exhaust back pressure when in a low load, and the exhaust back pressure does not rise too quickly when the internal combustion engine is in a high load. The invention further provides a device and system for optimizing the exhaust back pressure of the internal combustion engine.