A pneumatic muffler with complementary flow channel structures

Abstract

The disclosure provides a pneumatic muffler with a complementary flow channel structure, which comprises a shell and a mixing cavity, a complementary flow channel structure and a converging structure arranged in sequence in the shell, the complementary flow channel structure comprises a nozzle and a spiral structure arranged on the periphery of the nozzle, the inside of the mixing cavity, the nozzle and the converging structure are communicated to form a main flow channel, a gap is arranged between the outer side wall of the mixing cavity and the inner side wall of the shell, and the gap is communicated with the inside of the spiral structure to form a secondary flow channel communicated with the main flow channel; the nozzle comprises a nozzle body and a plurality of baffles arranged at intervals in the nozzle body, an air hole and a deflection ring are arranged on the side wall of the upstream side of the nozzle body, and each baffle is provided with a central through hole; the spiral structure comprises a plurality of thin-walled pipes arranged at intervals from inside to outside, so that the secondary flow channel in the spiral structure is distributed in a folded manner, the inner and outer side walls of adjacent two thin-walled pipes are connected through a spiral layer, and the outlet end of the secondary flow channel is located on the downstream side of the outermost thin-walled pipe in the spiral structure. The disclosure improves the noise reduction efficiency by introducing the complementary flow channel structure.

Description

Technical Field

[0001] This disclosure belongs to the field of acoustic engineering technology, and specifically proposes a pneumatic silencer with a complementary flow channel structure. Background Technology

[0002] Noise has a negative impact on human physical and mental health as well as the environment. In the engineering field, when the noise generated during the normal operation of equipment exceeds the tolerance limit, silencers need to be installed to suppress the noise.

[0003] For construction machinery, common noises include mechanical noise and exhaust noise. Mechanical noise typically originates inside the equipment, and noise reduction methods usually involve suppressing noise propagation. Exhaust noise is aerodynamic noise, and its source is generally located outside the equipment, requiring suppression of the noise source's intensity. The two types of noise have different generation principles and suppression methods, corresponding to different silencer structures.

[0004] The installation of silencers should not excessively affect equipment performance. For equipment with airflow, the minimum diameter of the silencer and the flow resistance need to be kept within a reasonable range to ensure normal operation of the equipment.

[0005] Traditional pneumatic silencers typically employ a multi-layered throttling structure. While they offer a compact size and good noise reduction, they often exhibit significant flow resistance, limiting their application. Classic expansion cavity silencers ensure airflow and provide some noise reduction, but they are primarily designed for linear noise and exhibit lower noise reduction efficiency when applied to aerodynamic noise. Summary of the Invention

[0006] This disclosure aims to at least partially address one of the technical problems in the related art.

[0007] Therefore, this disclosure proposes a pneumatic silencer with a complementary flow channel structure. By introducing a complementary flow channel structure with a nozzle-shaped main flow channel and a multi-layered folded secondary flow channel, the silencer can achieve a good effect of reducing aerodynamic noise within a limited volume, while retaining a certain diameter to reduce internal flow resistance. It is suitable for noise suppression of high-speed flowing gas.

[0008] To achieve the above objectives, the present disclosure adopts the following technical solution:

[0009] This disclosure provides a pneumatic muffler with a complementary flow channel structure, comprising a housing and a mixing chamber, a complementary flow channel structure, and a converging structure arranged sequentially within the housing in the direction of airflow. The complementary flow channel structure includes a nozzle and a spiral structure disposed around the nozzle. The interiors of the mixing chamber, the nozzle, and the converging structure are sequentially connected to form the main flow channel of the pneumatic muffler. A gap is provided between the outer wall of the mixing chamber and the inner wall of the housing, and this gap is connected to the interior of the spiral structure to form a secondary flow channel of the pneumatic muffler. The secondary flow channel is connected to the main flow channel.

[0010] The complementary flow channel structure includes a nozzle comprising a tube body and several baffles spaced apart within the tube body in the direction of airflow. A second vent and a deflector ring are provided on the side wall of the upstream side of the tube body, allowing airflow to flow only from the main flow channel into the secondary flow channel. Each baffle has a central through hole. The spiral structure includes multiple thin-walled tubes spaced apart from the inside to the outside. These multiple thin-walled tubes cause the secondary flow channels within the spiral structure to be distributed in a folded manner. The inner and outer walls of adjacent thin-walled tubes are connected by a spiral layer to induce airflow deflection. The outlet end of the secondary flow channel is located downstream of the outermost thin-walled tube within the spiral structure.

[0011] In some embodiments, the nozzle is a Laval nozzle, which is a thin-walled rotating body that is narrow in the middle and wide on both sides, and the nozzle, mixing chamber and convergence structure have the same diameter at the narrowest point.

[0012] In some embodiments, each baffle is a bowl-shaped frustum-shaped thin-walled rotating body, and each thin-walled rotating body has the same minimum diameter and the end with the largest diameter is located closer to the outlet end of the nozzle than the end with the largest diameter.

[0013] In some embodiments, the second vent and the deflection ring are provided near the first 1 to 2 baffles on the upstream side of the pipe body.

[0014] In some embodiments, the second vent holes are arranged circumferentially on the sidewall of the upstream side of the pipe.

[0015] In some embodiments, the bias ring has a structure that protrudes toward the outer shell.

[0016] In some embodiments, an annular body is provided between the outer wall of the narrowest part of the nozzle and the inner wall of the adjacent thin-walled tube, and a spiral hole is provided on the annular body.

[0017] In some embodiments, the housing includes a first sleeve having an air inlet and an air outlet, both of which are threaded.

[0018] In some embodiments, the mixing chamber is a cylindrical body with a first vent hole on its side wall, the first vent hole being used to connect the main flow channel and the secondary flow channel; the outlet end of the mixing chamber is a cylinder with a central through hole, the inner diameter of the through hole increasing sequentially along the airflow direction.

[0019] In some embodiments, the convergence structure consists of a bowl-shaped frustum-shaped thin-walled rotating body and an outlet pipe connected together. The inner diameter of the bowl-shaped frustum-shaped thin-walled rotating body increases in the direction of airflow, and its minimum diameter is the same as the diameter at the narrowest point of the nozzle.

[0020] The features and beneficial effects of this disclosure are as follows:

[0021] 1. Under suitable operating conditions, the main flow channel of the nozzle shape can induce a strong shock wave at the outlet, consume airflow energy, reduce airflow speed, and thus effectively suppress aerodynamic noise.

[0022] 2. Taking advantage of the nozzle's narrow center and wide ends, a multi-layered folded secondary flow channel structure was designed to fit snugly against the nozzle, making full use of the limited internal space of the muffler and improving its noise reduction efficiency.

[0023] 3. The secondary flow channel formed in conjunction with the nozzle uses structures such as recirculation and spiral to increase the airflow path, induce the airflow to increase the flow path and generate vortices, thereby consuming energy and reducing noise.

[0024] 4. Flow-through design, which retains the smallest diameter nozzle and mixing chamber, can reduce flow resistance, suppress gas backflow, reduce maximum working pressure, and help improve the life and working stability of the equipment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the outer contour of a pneumatic silencer with a complementary flow channel structure provided in an embodiment of this disclosure.

[0026] Figure 2 yes Figure 1 The diagram shows a three-dimensional view of the internal structure of the pneumatic silencer.

[0027] Figure 3 yes Figure 1 The diagram shows a cross-sectional view of the pneumatic silencer.

[0028] Figure 4 yes Figure 1 The diagram shows the structure of the secondary flow channel within the complementary flow channel structure of the pneumatic silencer. It also shows a schematic diagram of the internal noise reduction structure of this invention.

[0029] Figure 5 The medium shaded area is Figure 1 The diagram shows the location of the spiral structure within the complementary flow channel structure of the pneumatic silencer.

[0030] Figure 6 yes Figure 1 The diagram shows the airflow direction inside the pneumatic silencer.

[0031] In the picture:

[0032] 1-Outer shell, 11-Inlet end, 12-Outlet end;

[0033] 2-Mixing chamber, 21-Inlet end, 22-Outlet end, 211, 222-Through holes, 221-Frustum, 23-First vent hole;

[0034] 3-Complementary flow channel structure, 31-Nozzle, 311-Pipe body, 3111-Second vent, 3112-Deflection ring, 312-Baffle, 32-Helical structure, 321-Thin-walled tube, 322-Helical layer, B11-Ring body, B111-Helical hole;

[0035] 4-Convergence structure, 41-Thin-walled rotating body, 42-Outlet pipe;

[0036] A - Main flow channel, B - Secondary flow channel, a - Inlet, b - Outlet. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the application will be described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application.

[0038] Conversely, this application covers any alternatives, modifications, equivalent methods, and schemes made within the spirit and scope of this application as defined by the claims. Furthermore, to provide the public with a better understanding of this application, certain specific details are described in detail below. However, this application can be fully understood by those skilled in the art even without these detailed descriptions.

[0039] In the description of this disclosure, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the foundation or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0041] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0042] See Figures 1-5This disclosure provides a pneumatic muffler with a complementary flow channel structure, comprising an outermost shell 1 and a mixing chamber 2, a complementary flow channel structure 3, and a converging structure 4 arranged sequentially within the shell 1 in the direction of airflow (in this embodiment, the airflow direction is from right to left). The complementary flow channel structure 3 includes a nozzle 31 and a spiral structure 32 disposed around the nozzle 31. The interiors of the mixing chamber 2, the nozzle 31, and the converging structure 4 are sequentially connected to form the main flow channel A of the pneumatic muffler of this embodiment. A gap is provided between the outer side wall of the mixing chamber 2 and the inner side wall of the shell 1, and this gap is connected to the interior of the spiral structure 32, together forming the secondary flow channel B of the pneumatic muffler of this embodiment.

[0043] The outer casing 1 adopts a first sleeve, and the two ends of the outer casing 1 are an air inlet 11 and an air outlet 12, respectively;

[0044] The mixing chamber 2 is a cylindrical body with a first vent hole 23 on the side wall. The main channel A and the secondary channel B are connected through the first vent hole 23. The two ends of the cylindrical body are the air inlet 21 and the air outlet 22 of the mixing chamber 2, respectively.

[0045] In the complementary flow channel structure 3, the nozzle 31 includes a pipe body 311 and several baffles 312 arranged at intervals in the direction of airflow within the pipe body 311. A second vent 3111 and a deflection ring 3112 are provided on the side wall on the upstream side of the pipe body 311, so that the airflow can only flow into the secondary flow channel B from the main flow channel A. Each baffle 312 is provided with a central through hole 3211. The spiral structure 32 includes a plurality of thin-walled tubes 321 arranged at intervals from the inside to the outside. The secondary flow channels in the spiral structure 32 are distributed in a folded manner through the plurality of thin-walled tubes 321. The inner and outer walls of two adjacent thin-walled tubes 321 are connected by a spiral layer 322 to induce the airflow to bend. The outlet end of the secondary flow channel B is located downstream of the outermost thin-walled tube 321 in the spiral structure 32. The airflow in the secondary flow channel B finally merges into the main flow channel A from the outlet end of the secondary flow channel B.

[0046] The converging structure 4 is used to stabilize the airflow and allow it to enter the downstream equipment in a converged rather than diffused manner.

[0047] In some embodiments, the first sleeve of the housing 1 is a cylindrical sleeve. Except for the air inlet end 11, the cross-section of the first sleeve is a concentric circle with equal inner and outer diameters. The first sleeve smoothly narrows at the air inlet end 11. The air inlet end 11 and the air outlet end 12 of the housing 1 are respectively threaded for connection with upstream and downstream equipment.

[0048] In some embodiments, see Figure 2 , Figure 3The outlet end 22 of the mixing chamber 2 is a cylinder with a central through-hole 222. Considering that the gas pressure in the muffler is the highest in the mixing chamber 2 and the mixing chamber 2 is subjected to the most severe impact, the inner diameter of the through-hole 222 is gradually increased along the airflow direction. That is, the outlet end 22 of the mixing chamber 2 adopts a gradually expanding design, which is a bowl-shaped frustum-shaped rotating body. Its cross-sectional curve is determined by cubic spline interpolation, which helps to extend the life of the mixing chamber 2. In addition, the gradually expanding design of the outlet end 22 of the mixing chamber 2 helps to force more gas into the secondary flow channel B. From an aerodynamic point of view, the gradually expanding structure can induce the formation of shock waves, which can dissipate more airflow energy. The minimum diameter of the through-hole 222 is the minimum diameter in the entire muffler. This minimum diameter is determined by the gas flow rate and velocity entering the muffler. A raised frustum 221 is provided on the upstream side of the through-hole 222 to facilitate the positioning of the through-hole 222 during processing. The air inlet 21 of the mixing chamber 2 is a cylinder with a through hole 211 larger than the through hole 222. Several strip-shaped first vent holes 23 are evenly distributed on the side wall of the mixing chamber 2, with the axial direction of each first vent hole 23 parallel to the axial direction of the mixing chamber 2. In this embodiment, three first vent holes 23 are distributed on the side wall of the mixing chamber 2. The mixing chamber 2 serves two purposes: firstly, it mixes the airflow to reduce the impact of the airflow on the internal structure of the muffler located downstream of the mixing chamber 2; secondly, it divides the airflow, with one part entering the main flow channel A and the other part entering the secondary flow channel B.

[0049] In some embodiments, the complementary flow channel structure 3 serves as the core functional element of the pneumatic silencer in this embodiment, increasing the airflow path, guiding airflow vortices, and generating shock waves at the nozzle orifice, thus achieving energy dissipation and noise reduction effects. Specifically, the airflow in the main flow channel A is guided by the contraction-expansion structure of the nozzle 31 and several internal baffles 312. Part of the airflow enters the secondary flow channel B (not limited by the minimum diameter) through the first two baffles and the second vent 3111, while the other part enters the main flow channel A and forms a shock wave at the nozzle orifice. The gas entering the secondary flow channel B undergoes a spiral and reverse flow, exiting from the outermost side of the secondary flow channel B, mixing and interfering with the gas in the main flow channel A, increasing the shock wave intensity, and achieving a noise reduction effect. See also Figures 2-5(The dotted line in the figure represents the central axis of the pneumatic silencer in this embodiment). The main channel A is formed inside the nozzle 31, located at the innermost part of the entire pneumatic silencer. The nozzle 31 is a Laval nozzle, and the tube body 311 of the nozzle 31 is a thin-walled rotating body that is wide at both ends and narrow in the middle. In this embodiment, five baffles 312 are spaced apart inside the tube body 311 of the nozzle 31. Each baffle 312 is a bowl-shaped frustum-shaped thin-walled rotating body, which helps to induce airflow turbulence in the relatively wide tube body 311, consume energy, and ensure noise reduction effect. In addition, the inner diameter of each bowl-shaped frustum-shaped thin-walled rotating body increases in the direction of airflow, which can better consume gas energy. The minimum diameter of each baffle 312, the diameter of the narrowest part of the nozzle 31, and the minimum diameter of the outlet end 22 of the mixing chamber 2 are the same. A second vent 3111 and a deflection ring 3112 are provided on the side wall of the pipe body 311 upstream. The second vent 3111 are evenly distributed on the side wall of the pipe body 311 in a circumferential manner. According to experimental measurements, the first 1 to 2 baffles on the upstream side of the pipe body 311 have the most significant impact on noise reduction. Therefore, the second vent 3111 and the deflection ring 3112 are set near the first 1 to 2 baffles on the upstream side of the pipe body 311. In this embodiment, a ring of radially evenly distributed through holes is opened between the first, second and second and third baffles on the upstream side of the airflow as the second vent 3111, and a matching deflection ring 3112 protruding towards the outer shell 1 is provided on the side wall of the pipe body 311 upstream of each second vent 3111.

[0050] In the complementary flow channel structure 3 of this embodiment, the spiral structure 32 has two thin-walled tubes (the following factors should be considered when determining the number of thin-walled tubes: preventing the accumulation of solids accidentally mixed in the airflow from clogging the secondary flow channel, and the limitation of processing accuracy). The first thin-walled tube is located inside the second thin-walled tube. The first spiral layer and the second spiral layer are connected between the first thin-walled tube and the second thin-walled tube, and between the second thin-walled tube and the outer shell 1, respectively. Therefore, the secondary flow channel B in the spiral structure 32 is a three-layer partially folded flow channel, namely the inner flow channel B1, the middle flow channel B2 and the outer flow channel B3. The inner flow channel B1 is formed between the tube body 311 and the first thin-walled tube, the middle flow channel B2 is formed between the first thin-walled tube and the second thin-walled tube, and the outer flow channel B3 is formed between the second thin-walled tube and the outer shell 1. An air inlet a and an air outlet b, which are connected to the main flow channel A, are respectively provided on the upstream side of the inner flow channel B1 and the downstream side of the outer flow channel B3. An annular body B11 is provided in the inner flow channel B1 corresponding to the narrowest point of the nozzle 31 to connect the outer wall of the pipe body 311 with the inner wall of the first thin-walled pipe, so as to enhance the structural stability of the muffler. A spiral hole B111 is provided on the annular body B11 to help the airflow form a vortex.

[0051] In some embodiments, the convergence structure 4 consists of a bowl-shaped frustum-shaped thin-walled rotating body 41 and an outlet pipe 42 connected together. The inner diameter of the bowl-shaped frustum-shaped thin-walled rotating body 41 increases in the direction of airflow, and its minimum diameter is the same as the diameter at the narrowest point of the nozzle 31. Uniformly distributed vent holes are provided on the outer wall of the convergence structure 4 for airflow exchange between the main and secondary channels, so that the flow rate is evenly distributed at all distances from the axis.

[0052] In this embodiment, the connection relationship of each component is as follows: the air inlet end of the outer shell 1 and the air inlet end of the mixing chamber 2 are locally fixedly connected at six equidistant points around the circumference, without affecting the airflow. The inner wall of the outer shell 1 serves as the outer wall of the outer channel B3 in the secondary channel B, and the outer shell 1 is connected to the inner wall of the outer channel B3 through the second spiral layer of the secondary channel B. The inner wall of the inner channel B1 of the secondary channel B, i.e., the side wall of the pipe body 311, is also the outer wall of the main channel A. The main channel A and the secondary channel B are connected through the first vent 23 on the mixing chamber 2 and the second vent 3111 on the upstream side of the pipe body 311. The spiral hole section in the middle of the innermost side of the secondary channel B has the same axial coordinate as the narrowest point of the main channel A. The outlet of the outer channel B3 of the secondary channel B is connected to the outlet of the main channel A. Overall, the main channel A and the secondary channel B form a complementary structure, together constituting a noise-absorbing structure with a rectangular cross-sectional outline. The outer shell 1 has threads at both ends, and the rightmost end is appropriately narrowed to facilitate connection with other equipment.

[0053] The following describes the installation and operation process of the pneumatic silencer provided in the embodiments of this disclosure:

[0054] (1) Installation: The pneumatic silencer in this embodiment is connected to the upstream and downstream equipment by tightening the threads at both ends of the housing 1. The leftmost thread can also be directly connected to the atmosphere without being connected to other equipment.

[0055] (2) Work process: See Figure 6 (The dashed line in the figure represents the central axis of the pneumatic silencer in this embodiment. The figure only shows the gas flow direction in the upper half of the silencer; the lower half is the same as the upper half.) This is a schematic diagram of the gas flow direction inside the pneumatic silencer of this embodiment. After the pneumatic silencer of this embodiment is connected to the upstream equipment, when the upstream equipment is working normally, the incoming flow enters the mixing chamber 2 from the right side. The mixing chamber 2 plays a stabilizing role, so that the airflow entering the pneumatic silencer but not reaching the complementary flow channel structure 3 is pre-mixed and flows smoothly, preventing it from impacting the complementary flow channel structure 3. The mixing chamber 2 also plays a diversion role, causing the gas to be divided into two streams that enter the main flow channel A and the secondary flow channel B respectively. The gradually expanding structure of the outlet end 22 of the mixing chamber 2 induces more airflow to flow to the edge of the secondary flow channel B.

[0056] When this pneumatic silencer is working, the gas flow path of the main flow channel A is as follows: The airflow entering the main flow channel A flows in the "contraction-expansion" structure formed by the nozzle 31's body 311 and five baffles 312, losing energy during compression and expansion; when the outlet pressure is appropriate, the nozzle 31 will induce the airflow to generate a shock wave at the outlet of the main flow channel A to consume energy. Two sets of side holes leading to the secondary flow channel B are opened between the first three baffles 312 on the upstream side of the nozzle 31, serving as second vent holes 3111, further diverting the high-pressure airflow in the main flow channel A to the secondary flow channel B. (The basis for diverting the gas from the main flow channel A to the secondary flow channel B is based on theoretical calculations and engineering practice; the noise reduction effect of the secondary flow channel B is better than that of the main flow channel A because the main flow channel A has a minimum diameter limitation under operating conditions, while the secondary flow channel B does not have this limitation.)

[0057] When this pneumatic silencer is working, the gas flow path in the secondary channel B is as follows: The gas diverted through the mixing chamber 2 first enters the inner channel B1, where it merges with the gas passing through the second vent 3111. The deflecting ring 3112 on the inner wall of the inner channel B1 covers the second vent 3111, preventing gas in the secondary channel B from flowing into the main channel A. After merging, the gas passes through the spiral hole B111 in the middle of the inner channel B1, achieving a compression effect and guiding the airflow to generate vortices that consume energy. The gas then rotates back from the end of the inner channel B1 into the middle channel B2, where it is deflected and vortexed in the first spiral layer of the middle channel B2, rotating back into the outer channel B3, and reaching the outlet of the main channel A through the outer channel B3, increasing the outlet pressure of the nozzle 31. The inner spiral hole B111 and the first and second spiral layers can suppress the backflow generated by the airflow during rotation, ensuring the unidirectional flow.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A pneumatic silencer with a complementary flow channel structure, characterized in that, The device includes an outer shell and a mixing chamber, a complementary flow channel structure, and a converging structure arranged sequentially within the outer shell in the direction of airflow. The complementary flow channel structure includes a nozzle and a spiral structure disposed around the nozzle. The interiors of the mixing chamber, the nozzle, and the converging structure are connected sequentially to form the main flow channel of the pneumatic muffler. A gap is provided between the outer wall of the mixing chamber and the inner wall of the outer shell, and this gap is connected to the interior of the spiral structure to form the secondary flow channel of the pneumatic muffler. The secondary flow channel is connected to the main flow channel. The complementary flow channel structure includes a nozzle comprising a tube body and several baffles spaced apart within the tube body in the direction of airflow. A second vent and a deflector ring are provided on the side wall of the upstream side of the tube body, allowing airflow to flow only from the main flow channel into the secondary flow channel. Each baffle has a central through hole. The spiral structure includes multiple thin-walled tubes spaced apart from the inside to the outside. These multiple thin-walled tubes cause the secondary flow channels within the spiral structure to be distributed in a folded manner. The inner and outer walls of adjacent thin-walled tubes are connected by a spiral layer to induce airflow deflection. The outlet end of the secondary flow channel is located downstream of the outermost thin-walled tube within the spiral structure. The converging structure consists of a bowl-shaped frustum-shaped thin-walled rotating body and an outlet pipe connected together. The inner diameter of the bowl-shaped frustum-shaped thin-walled rotating body increases in the direction of airflow, and its minimum diameter is the same as the diameter at the narrowest point of the nozzle.

2. The pneumatic silencer according to claim 1, characterized in that, The nozzle is a Laval nozzle, which is a thin-walled rotating body that is narrow in the middle and wide on both sides. The nozzle, mixing chamber and convergence structure have the same diameter at the narrowest point.

3. The pneumatic silencer according to claim 1, characterized in that, Each baffle is a bowl-shaped, frustum-shaped, thin-walled rotating body. The minimum diameter of each thin-walled rotating body is the same, and the end with the largest diameter is closer to the outlet end of the nozzle than the end with the largest diameter.

4. The pneumatic silencer according to claim 1, characterized in that, The second vent and the deflection ring are provided near the first 1 to 2 baffles on the upstream side of the pipe.

5. The pneumatic silencer according to claim 1, characterized in that, The second vent is evenly distributed around the circumference on the side wall of the upstream side of the pipe.

6. The pneumatic silencer according to claim 1, characterized in that, The deflection ring has a structure that protrudes towards the outer shell.

7. The pneumatic silencer according to claim 1, characterized in that, A ring is provided between the outer wall of the narrowest part of the nozzle and the inner wall of the adjacent thin-walled tube to connect the two, and a spiral hole is provided on the ring.

8. The pneumatic silencer according to claim 1, characterized in that, The housing includes a first sleeve having an air inlet and an air outlet, both of which are threaded.

9. The pneumatic silencer according to claim 1, characterized in that, The mixing chamber is a cylindrical body with a first vent hole on the side wall, which is used to connect the main flow channel and the secondary flow channel; the outlet end of the mixing chamber is a cylinder with a central through hole, and the inner diameter of the through hole increases sequentially along the airflow direction.

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