Two-stroke internal combustion engine, exhaust device and unmanned aerial vehicle

Abstract

The invention discloses a two-stroke internal combustion engine, an exhaust device and an unmanned aerial vehicle, the two-stroke internal combustion engine comprises an air cylinder and the exhaust device, the exhaust device is connected with an exhaust port of the air cylinder, the exhaust device comprises a pipe body, and an air inlet, a partition plate set and the exhaust port are sequentially arranged in the pipe body in the exhaust direction; the air inlet is directly or indirectly connected with an exhaust port of a cylinder of the two-stroke internal combustion engine; the partition plate set comprises a pressure return partition plate and a noise reduction partition plate set which are sequentially arranged in the exhaust direction, the noise reduction partition plate set comprises two or more noise reduction partition plates, a pressure return chamber is formed by the space between the pressure return partition plate and the inner wall of the front end of the pipe body, and a noise reduction chamber is formed by the space between the pressure return partition plate and the inner wall of the rear end of the pipe body. Exhaust through hole arrays composed of a plurality of exhaust through holes are arranged on the back pressure partition plate and the silencing partition plates, and the exhaust through hole arrays of the back pressure partition plate and the first silencing partition plate are staggered in the radial direction of the pipe body; an exhaust port of the exhaust device is used for exhausting tail gas. The staggered design enables sound wave energy to be absorbed, and noise is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine exhaust, and more particularly to a two-stroke internal combustion engine, an exhaust device, and an unmanned aerial vehicle. Background Technology

[0002] Two-stroke internal combustion engines are a type of internal combustion engine that completes one working cycle in two strokes. They have advantages such as high power density and rapid start-up, and are widely used in equipment such as drones and motorboats.

[0003] In the operation of a two-stroke internal combustion engine, fresh air-fuel mixture enters the cylinder through the scavenging passage, expelling the combusted exhaust gases from the exhaust port, completing the scavenging process. To improve scavenging efficiency, theoretically, the exhaust port should be as large as possible to facilitate rapid exhaust gas discharge; however, increasing the exhaust port size shortens the effective power stroke of the piston, thus reducing the engine's energy utilization rate. To balance power performance and energy efficiency, the exhaust port is usually designed to be smaller, which leads to increased exhaust resistance. Due to the limited exhaust port size, exhaust gases cannot be completely expelled from the cylinder, and some residual exhaust gases participate in the combustion process along with the newly entered air-fuel mixture. Furthermore, in the initial stage of exhaust, there is still high pressure in the combustion chamber, and some unburned fuel is directly discharged into the exhaust system with the exhaust gases, resulting in energy waste and generating strong pulsating airflow and high-frequency noise. Therefore, two-stroke internal combustion engines are often accompanied by significant exhaust noise during operation.

[0004] To address these issues, existing technologies have made relevant attempts. For example, Chinese utility model patent CN206111275U discloses a resonant tube structure for drones. This resonant tube includes an air inlet, a resonant chamber, a resonant chamber baffle, a sealed soundproof chamber, a sealed soundproof chamber baffle, a silencer chamber, a silencer chamber baffle, and an exhaust pipe. Each silencer chamber baffle has multiple air vents, and the air vents on adjacent silencer chamber baffles are arranged opposite each other. This structure, through the design of multi-stage baffles and air vents, achieves noise suppression to a certain extent, but there is still room for improvement in noise reduction. Summary of the Invention

[0005] Therefore, it is necessary to provide a two-stroke internal combustion engine, an exhaust device, and a drone to solve the problem of insufficient noise reduction performance of the two-stroke internal combustion engine during exhaust.

[0006] To achieve the above objectives, the inventor provides a two-stroke internal combustion engine, including a cylinder and an exhaust device, wherein the exhaust device is directly or indirectly connected to the exhaust port of the cylinder, and the exhaust device includes: a pipe body, wherein an air inlet, a baffle group and an exhaust port are sequentially arranged in the exhaust direction within the pipe body;

[0007] The air intake is directly or indirectly connected to the exhaust port of the cylinder of the two-stroke internal combustion engine.

[0008] The baffle assembly includes a backpressure baffle and a noise-absorbing baffle assembly arranged sequentially along the exhaust direction. The noise-absorbing baffle assembly includes two or more noise-absorbing baffles. The space between the backpressure baffle and the inner wall of the front end of the pipe body forms a backpressure chamber. The front end of the pipe body is the end of the pipe body near the air inlet. The space between the backpressure baffle and the inner wall of the rear end of the pipe body forms a noise-absorbing chamber. The rear end of the pipe body is the end of the pipe body near the exhaust port of the exhaust device. Both the backpressure baffle and the noise-absorbing baffle are provided with an exhaust hole array consisting of multiple exhaust holes. The proportion of the exhaust hole arrays of the backpressure baffle and the first noise-absorbing baffle being offset in the radial direction of the pipe body is not less than 80%. The first noise-absorbing baffle is the one closest to the backpressure baffle in the noise-absorbing baffle assembly.

[0009] The exhaust port of the exhaust device is used to discharge exhaust gas or to connect to an exhaust gas emission device.

[0010] Further: the backpressure baffle and / or the sound-absorbing baffle includes a plate body and a plurality of protrusions, the plate body having a first vent hole, the protrusions having a second vent hole, the protrusions being fixed to the plate body and the second vent hole communicating with the first vent hole to form a venting through hole, one first vent hole corresponding to one protrusion; or,

[0011] The exhaust vents located on the back pressure baffle and / or the sound-absorbing baffle are formed by stamping the back pressure baffle and / or the sound-absorbing baffle; or,

[0012] The perforated plates on the back pressure baffle and / or the sound-absorbing baffle are bent toward the rear or front end of the pipe body, so that the original position of the back pressure baffle and / or the sound-absorbing baffle corresponding to the perforated plates forms the exhaust passage. The outer edge of the perforated plate is adapted to the inner edge of the exhaust passage, and the perforated plate is connected to the back pressure baffle and / or the sound-absorbing baffle through a connecting part.

[0013] Furthermore, the exhaust hole arrays of the back pressure baffle and the first silencer baffle are offset by no less than 90% in the radial direction of the pipe body.

[0014] Furthermore, the exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle group are staggered by no less than 80% in the radial direction of the pipe body.

[0015] Furthermore, the exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle group are staggered by no less than 80% in the circumferential direction of the pipe body.

[0016] Furthermore: the exhaust hole array of the back pressure baffle is positioned closer to the outer periphery of the baffle than the exhaust hole array of the first sound-absorbing baffle;

[0017] The exhaust vent arrays of adjacent back pressure baffles and sound-absorbing baffles, as well as the two adjacent sound-absorbing baffles, are arranged alternately near the outer periphery of the baffles and near the center of the baffles.

[0018] Furthermore: the two sound-absorbing baffles set at intervals have the same structure.

[0019] Furthermore, the back pressure baffle and the second sound-absorbing baffle are structurally mirror images of each other, and the second sound-absorbing baffle is the one closest to the first sound-absorbing baffle in the sound-absorbing baffle group.

[0020] Furthermore, the back pressure baffle is a curved surface that protrudes towards the first sound-absorbing baffle.

[0021] Furthermore, the first sound-absorbing baffle has a curved surface that protrudes towards the direction of the back pressure baffle.

[0022] Furthermore, the inner wall of the front end of the tube is a curved surface that bulges towards the air inlet.

[0023] Furthermore, the area of ​​the exhaust through-hole array is 550–935 mm². 2 The diameter of a single exhaust port is 5 to 10 mm.

[0024] Furthermore, the center distance between two adjacent exhaust through-hole arrays in the radial direction of the pipe body is 0.35R to 0.6R, where R is the distance from the center of the partition to the outer periphery.

[0025] Furthermore: the exhaust port of the exhaust device is provided on the exhaust pipe, and the exhaust pipe extends into the silencer chamber from the rear end of the pipe body.

[0026] To achieve the above objectives, the inventors also provide a two-stroke internal combustion engine exhaust device, wherein the exhaust device is the exhaust device described in any of the above embodiments.

[0027] To achieve the above objectives, the inventors also provide an unmanned aerial vehicle (UAV) including a two-stroke internal combustion engine as described in any of the above embodiments.

[0028] Unlike existing technologies, the above technical solution has the following beneficial effects:

[0029] When a two-stroke internal combustion engine is running, high-temperature and high-pressure exhaust gas is discharged from the engine exhaust port and enters the intake port of this exhaust device. The exhaust gas first enters the back pressure chamber. The presence of the back pressure baffle causes some of the fresh combustible mixture to be drawn back into the cylinder of the two-stroke internal combustion engine for re-combustion in this space. The other part of the airflow enters the muffler chamber through the exhaust port array on the back pressure baffle. Since the exhaust ports between the back pressure baffle and the first muffler baffle are offset by at least 80% radially, this offset design prevents the airflow from passing through the pipe axially, forcing it to change its flow direction. The path becomes significantly longer, resulting in multiple collisions inside the pipe, which leads to the loss of airflow kinetic energy and the absorption of sound wave energy, thereby significantly reducing noise.

[0030] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0031] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of the present invention and other related contents, and should not be considered as limitations on this application.

[0032] Figure 1 This is a schematic diagram of the exhaust system of a two-stroke internal combustion engine in this embodiment;

[0033] Figure 2 This is a schematic diagram of the internal structure of the exhaust device in Embodiment 2;

[0034] Figure 3 This is an exploded view of the back pressure baffle and the first sound-absorbing baffle in Example 2;

[0035] Figure 4 This is an exploded view of the back pressure baffle and the five sound-absorbing baffles in Example 2;

[0036] Figure 5 This is one of the exploded views of the backpressure baffle and the four sound-absorbing baffles in Example 1;

[0037] Figure 6 for Figure 5 Enlarged view of part A in the middle;

[0038] Figure 7 This is a schematic diagram of the exhaust port of the back pressure baffle in Example 1;

[0039] Figure 8 for Figure 7 Enlarged view of section C;

[0040] Figure 9This is an exploded view of the back pressure baffle and the five sound-absorbing baffles in Example 3;

[0041] Figure 10 for Figure 9 Enlarged view of part B in the middle;

[0042] Figure 11 This is a schematic diagram of the exhaust pipe extending from the rear end of the pipe body into the silencing chamber and the silencing baffle in Embodiment 1;

[0043] Figure 12 This is a projection view of two adjacent exhaust port arrays in some embodiments;

[0044] Figure 13 This is a projection view of two adjacent exhaust port arrays in some embodiments;

[0045] Figure 14 This is a schematic diagram of the internal structure of the exhaust device in Embodiment 1;

[0046] Figure 15 This is the second exploded view of the back pressure baffle and the four sound-absorbing baffles in Example 1;

[0047] Figure 16 This is a schematic diagram of a tubular component in some embodiments.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Pipe body; 11. Air inlet; 12. Exhaust outlet; 13. Back pressure chamber; 14. Silencer chamber; 15. Exhaust pipe; 16. Front inner wall; 17. Rear inner wall; 18. Exhaust gas treatment device; 19. Tubular component;

[0050] 2. Back pressure baffle;

[0051] 3. Sound-absorbing barrier assembly; 31. First sound-absorbing barrier; 32. Second sound-absorbing barrier; 33. Third sound-absorbing barrier; 34. Fourth sound-absorbing barrier; 35. Fifth sound-absorbing barrier;

[0052] 4. Exhaust vent array; 41. Exhaust vent; 42. Plate; 43. Protrusion; 44. First exhaust vent; 45. Second exhaust vent; 46. Annular groove;

[0053] 5. Perforated plate; 51. Connecting part. Detailed Implementation

[0054] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0055] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0056] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0057] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0058] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0059] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0060] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0061] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. They are only for the purpose of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0062] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0063] Please see Figures 1 to 16 This embodiment provides a two-stroke internal combustion engine, including a cylinder and an exhaust device. The exhaust device is directly or indirectly connected to the exhaust port of the cylinder. The exhaust device includes: a pipe body 1.

[0064] The pipe body 1 has an air inlet 11, a baffle group and an exhaust outlet 12 arranged sequentially along the exhaust direction;

[0065] The air intake 11 is directly or indirectly connected to the exhaust port of the cylinder of the two-stroke internal combustion engine.

[0066] The baffle assembly includes a backpressure baffle 2 and a noise-absorbing baffle assembly 3 arranged sequentially along the exhaust direction. The noise-absorbing baffle assembly 3 includes two or more noise-absorbing baffles. The space between the backpressure baffle 2 and the inner wall 16 at the front end of the pipe body forms a backpressure chamber 13. The front end of the pipe body is the end of the pipe body near the air inlet 11. The space between the backpressure baffle 2 and the inner wall 17 at the rear end of the pipe body forms a noise-absorbing chamber 14. The rear end of the pipe body is the end of the pipe body near the exhaust port 12. Both the backpressure baffle 2 and the noise-absorbing baffle are provided with an exhaust hole array composed of multiple exhaust holes. The proportion of the exhaust hole arrays of the backpressure baffle 2 and the first noise-absorbing baffle 31 being offset radially from each other in the pipe body 1 is not less than 80%. The first noise-absorbing baffle 31 is the one closest to the backpressure baffle 2 in the noise-absorbing baffle assembly 3.

[0067] The exhaust port 12 is used to discharge exhaust gas or to connect to an exhaust gas emission device.

[0068] Tube 1 is a hollow cylindrical structure, such as Figure 1 and Figure 2 In the embodiment shown, the air inlet 11 is located at one end of the pipe body 1, as shown... Figure 1 and Figure 2 The right end of the pipe body 1 can be fitted onto the exhaust port of a two-stroke internal combustion engine to collect the exhaust gas discharged from the engine. The exhaust port 12 is located at the other end of the pipe body 1, such as... Figure 1 and Figure 2 From the left end of the device, a portion of the treated waste gas is discharged. The exhaust direction is from the inlet 11 of the exhaust device towards the outlet 12. Figure 1 and Figure 2 The center also corresponds to the axial direction of tube 1, such as... Figure 2 As indicated by the middle arrow z, the back pressure baffle 2 and the noise reduction baffle group 3 are located in the hollow space of the pipe body 1, between the air inlet 11 and the exhaust port 12, which serve to allow some fresh combustible mixture to be re-injected into the cylinder and to reduce noise.

[0069] The exhaust port array 4 refers to a plurality of exhaust ports 41 distributed on a baffle (such as a back pressure baffle 2 or a sound-absorbing baffle) for exhaust, and these exhaust ports are arranged in a certain pattern or irregularly to form an integral structure, such as... Figures 2 to 3 As shown. A regular array can be a circular array, a rectangular array, a wavy array, etc., where the center of the array is usually the center of the partition (coaxially aligned with tube 1). Figure 3 The exhaust port array of the back pressure baffle 2 and the first noise-absorbing baffle 31 is shown to be a circular array. In contrast, an irregular, random arrangement does not follow a specific geometric pattern and is distributed randomly. A key point of this embodiment is that the exhaust port array of the back pressure baffle 2 and the first noise-absorbing baffle 31 is radially aligned with the pipe body 1 (e.g., ...). Figure 3 The offset ratio (indicated by the arrow y) is not less than 80%. This means that most of the exhaust holes of the back pressure baffle 2 and the first sound-absorbing baffle 31 are offset radially in the pipe body 1, but a small portion of the exhaust holes may still overlap radially in the pipe body 1. If each baffle has 10 exhaust holes, and only 2 of them overlap radially in the pipe body 1 while the remaining 8 do not, then the offset ratio is 8 / 10 = 80%. In this case, the offset ratio is required to be not less than 80%, so there can be 8 exhaust holes offset radially in the pipe body 1, or 9 exhaust holes offset radially in the pipe body 1, or all 10 exhaust holes offset radially in the pipe body 1. Offset means that at the position corresponding to the exhaust holes on the back pressure baffle 2 in the y direction (i.e., the y direction of the radial plane of the pipe body 1) on the cross-section of the pipe body 1, there are no exhaust holes on the first sound-absorbing baffle 31.

[0070] In this embodiment, the reason for emphasizing that the holes are offset in the radial direction of the tube body 1 is that this offset does not include the fact that although the through holes on the two partition plates do not overlap, their distance from the radial direction (y direction) of the tube body 1 is still equal. They are offset only because they are rotated at different angles around the axial direction. Therefore, in this embodiment, it is assumed that the two exhaust through holes are not offset in the radial direction of the tube body 1. Thus, the offset is limited to the radial direction of the tube body 1, rather than a simple offset.

[0071] In this embodiment, a back pressure chamber 13 and a silencer chamber 14 are provided between the front and rear ends of the pipe body. Those skilled in the art should understand that the pipe body 1 is a structural concept and cannot be rigidly interpreted as a mechanical component. That is, in this application, the pipe body is a tubular structure, in which the back pressure chamber 13 and the silencer chamber 14 are divided by a baffle group. In a specific exhaust device embodiment, this pipe body can be a separate component or it can be incorporated into a component. For example, in a tubular component 19, in addition to the pipe body described in this application, this tubular component 19 also has an exhaust gas treatment device 18 (e.g., a three-way catalytic converter) after the exhaust port 12, with the structure as follows: Figure 16 As shown, however, it should be understood that these additional devices do not belong to the structural concept of the tube body in the application. Just because the front or rear part of the tubular component has a structure other than the tube body in a specific embodiment does not mean that it does not have the "tube body" structure described in this application. It should be considered that as long as the device has a "tube body" structure that conforms to the description in this application and has the same function, it should be considered to conform to the relevant description in this application.

[0072] The number of sound-absorbing baffles can be flexibly set according to actual needs, and 2, 3, 4 or even more can be selected. The more sound-absorbing baffles there are, the better the sound absorption effect, but the longer the pipe body will be. Therefore, in order to balance the size and sound absorption effect, 4 or 5 sound-absorbing baffles are preferred. Preferably, the sound-absorbing baffles are coaxially arranged, and the back pressure baffle is also coaxially arranged with the sound-absorbing baffles.

[0073] When the two-stroke internal combustion engine is running, high-temperature and high-pressure exhaust gas is discharged from the engine exhaust port and enters the intake port 11 of the exhaust device. The exhaust gas first enters the back pressure chamber 13. The presence of the back pressure baffle 2 causes part of the fresh combustible mixture to be drawn back into the cylinder of the two-stroke internal combustion engine for re-combustion in this space. The other part of the airflow enters the silencer chamber 14 through the exhaust hole array on the back pressure baffle 2. Since the exhaust holes between the back pressure baffle 2 and the first silencer baffle 31 are offset by no less than 80% of the radial position, this offset design prevents the airflow from passing through the axial direction of the pipe body 1 and forces it to change its flow direction. The path becomes significantly longer, and multiple collisions occur inside the pipe body 1, resulting in the loss of airflow kinetic energy and the absorption of sound wave energy, thereby significantly reducing noise.

[0074] Please see Figure 3In some embodiments, the exhaust port array 4 of the backpressure baffle 2 and the first noise-absorbing baffle 31 is offset by at least 90% radially in the pipe body 1. This means that, in the cross-section (i.e., the radial plane of the pipe body 1), at least 90% of the exhaust ports between the two baffles are offset radially in the pipe body 1. Only a maximum of 10% of the exhaust ports may overlap radially, allowing airflow to pass directly through. If each of the two baffles has 20 exhaust ports, and only 2 of them overlap radially in the pipe body 1 while the remaining 18 do not, the offset ratio is 18 / 20 = 90%. If each of the two baffles has 20 exhaust ports, and only 1 of them overlaps radially in the pipe body 1 while the remaining 19 do not, the offset ratio is 19 / 20 = 95%.

[0075] The higher the offset ratio, the more complex the airflow path, and the better the noise reduction effect. Preferably, the exhaust hole arrays of the backpressure baffle 2 and the first sound-absorbing baffle 31 are offset by 100% radially in the pipe body 1. Figure 3 As shown. Figure 3 The image shows the first silencing baffle 31 on the left and the backpressure baffle 2 on the right. Two exhaust holes 41 are provided at positions k1 and k2 on the first silencing baffle 31. These positions k1 and k2 correspond to positions k1' and k2' on the backpressure baffle 2 along the axial direction of the pipe body, respectively. No exhaust holes are provided at positions k1' and k2'. Similarly, two exhaust holes 41 are provided at positions k3 and k4 on the backpressure baffle 2. These positions k3 and k4 correspond to positions k3' and k4' on the first silencing baffle 31 along the axial direction of the pipe body, respectively. No exhaust holes are provided at positions k3' and k4'. This arrangement reflects the staggered design of the exhaust holes between adjacent baffles in the radial (y-direction) direction of the pipe body 1, which helps to enhance airflow disturbance and sound energy attenuation.

[0076] Please see Figure 2 and Figure 4 In some embodiments, the exhaust hole arrays 4 of two adjacent sound-absorbing baffles in the sound-absorbing baffle group 3 are offset by at least 80% radially in the pipe body 1. If each of the two sound-absorbing baffles has 10 exhaust holes 41, with only 2 exhaust holes overlapping radially in the pipe body 1 and the remaining 8 not overlapping, then the offset ratio is 8 / 10 = 80%. In this case, the offset ratio is required to be at least 80%, so there can be 8 exhaust holes offset radially in the pipe body 1, or 9 exhaust holes 41 offset radially in the pipe body 1, or all 10 exhaust holes 41 offset radially in the pipe body 1. Exhaust gas cannot pass through the exhaust hole 41 of one sound-absorbing baffle along the axial direction of the pipe body 1 to the exhaust hole 41 of the next sound-absorbing baffle; instead, it must bounce and detour to reach the position of the next sound-absorbing baffle. During this process, the airflow path is longer, the disturbance is stronger, and the sound energy attenuation is more efficient, thereby achieving an excellent noise reduction effect.

[0077] The higher the stagger ratio, the more complex the airflow path and the better the noise reduction effect. Preferably, the exhaust hole arrays of two adjacent sound-absorbing baffles are staggered by 100% in the radial direction of the pipe body 1. Figure 4 The diagram shows five sound-absorbing baffles, namely, the first sound-absorbing baffle 31, the second sound-absorbing baffle 32, the third sound-absorbing baffle 33, the fourth sound-absorbing baffle 34, and the fifth sound-absorbing baffle 35. The exhaust hole array 4 on these baffles is staggered by 100% in the radial direction of the pipe body 1. Because there are multiple sound-absorbing baffles, each staggered structure reprocesses the noise, and the noise energy is absorbed step by step, forming a cumulative noise reduction effect.

[0078] In some embodiments, the exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle assembly are staggered by no less than 80% in the circumferential direction of the pipe body. The circumferential direction of the pipe body refers to the direction along the circumference of the pipe body. The exhaust holes on the preceding and following sound-absorbing baffles are not located in the same circumferential position; that is, the exhaust holes of the two sound-absorbing baffles are not on the same radial direction of the pipe body. This circumferential staggered arrangement can be achieved by circumferentially offsetting the exhaust holes, for example, by using a rotation angle offset method, rotating the hole array of each sound-absorbing baffle relative to the preceding baffle by a certain angle (e.g., 15°, 30°, etc.) in the circumferential direction to achieve the desired staggered ratio. The circumferential staggered arrangement allows the sound wave path to change when passing through different baffles, improving the noise reduction effect. Preferably, the exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle assembly are staggered by 100% in the circumferential direction of the pipe body. Similarly, the exhaust port arrays of the back pressure baffle and the sound-absorbing baffle are staggered in the circumferential direction of the pipe body by a ratio of not less than 80%, preferably 100%.

[0079] Please see Figures 2 to 4 In some embodiments, the exhaust hole array of the back pressure baffle 2 is positioned closer to the outer periphery of the baffle than the exhaust hole array of the first sound-absorbing baffle 31; the exhaust hole arrays of adjacent back pressure baffles 2 and sound-absorbing baffles, as well as the two adjacent sound-absorbing baffles, are arranged alternately with the baffle positioned closer to the outer periphery and the baffle positioned closer to the center.

[0080] The outer periphery of a baffle refers to the area near its edge, that is, the part farther from the center of the baffle and closer to the side wall of the pipe body. In a circular baffle, it usually refers to the area around the circumference. The center of a baffle refers to the area near its center. In a circular baffle, it usually refers to the area at the center of the circle. The air inlet 11 is usually located at the center of the pipe body 1. The exhaust port array of the back pressure baffle 2 is positioned near the outer periphery of the baffle. The exhaust port array 4 of the first silencer baffle 31 is positioned near the center of the baffle and inside the exhaust port array of the back pressure baffle 2. The exhaust port array 4 of the second silencer baffle 32 is positioned near the outer periphery of the baffle and outside the exhaust port array 4 of the first silencer baffle 31. The second silencer baffle 32 is the one closest to the first silencer baffle 31 in the silencer baffle group 3. The exhaust port array 4 of the third silencer baffle 33 is positioned near the center of the baffle and inside the exhaust port of the second silencer baffle 32. Inside array 4, the third silencing baffle 33 is the one closest to the second silencing baffle 32 in the silencing baffle group 3, excluding the first silencing baffle 31. The exhaust hole array 4 of the fourth silencing baffle 34 is located near the outer periphery of the baffle and outside the exhaust hole array 4 of the third silencing baffle 33. The fourth silencing baffle 34 is the one closest to the third silencing baffle 33 in the silencing baffle group 3, excluding the second silencing baffle 32. The exhaust hole array 4 of the fifth silencing baffle 35 is located near the center of the baffle and inside the exhaust hole array 4 of the fourth silencing baffle 34. The fifth silencing baffle 35 is the one closest to the exhaust port 12 in the silencing baffle group 3. In other words, these exhaust vent arrays are arranged in an alternating cycle of outside-inside-outside-inside. This design requires the exhaust gas to undergo a flow change from outside to inside or from inside to outside when passing through each baffle, which greatly enhances the diffusion and collision of airflow and improves the noise reduction effect during the exhaust process.

[0081] Please see Figures 1 to 4 Preferably, the tube 1 selected in this embodiment is a circular tube, and the partition is a circular partition. The tube 1 and the partition are coaxially arranged, that is, the central axis of the tube 1 and the central axis of the partition are on the same straight line. However, those skilled in the art should know that a non-circular cross-section tube 1 (such as an elliptical, rectangular, or polygonal tube) and a partition of a corresponding shape (such as an elliptical, square, or polygonal partition) can be selected according to actual needs. As long as they can still achieve the core functions of staggered arrangement of exhaust vent array and airflow disturbance noise reduction, they should all fall within the protection scope of this embodiment.

[0082] Please see Figure 2 and Figure 4In some embodiments, two spaced-apart sound-absorbing baffles have identical structures. Identical structures mean that they are identical in geometry, size, number and distribution (i.e., array pattern) of exhaust vents, and vent size, but their positions within the anechoic chamber 14 differ. This simplifies the manufacturing and assembly process without sacrificing noise reduction performance, allowing for mass production of both types of baffles, which can be used alternately in sequence during assembly, thus reducing mold costs.

[0083] Please see Figure 5 In some embodiments, the back pressure baffle 2 and the second sound-absorbing baffle 32 are structurally mirror images of each other, and the second sound-absorbing baffle 32 is the one closest to the first sound-absorbing baffle 31 in the sound-absorbing baffle group 3. The back pressure baffle 2 and the second sound-absorbing baffle 32 can be produced with only one set of molds. During assembly, the second sound-absorbing baffle 32 can be flipped to make it mirror images of the back pressure baffle 2.

[0084] Please see Figure 4 and Figure 5 In some embodiments, the backpressure baffle 2 is a curved surface convex towards the first noise-reducing baffle 31, with the convex surface facing the air intake 11 and the concave surface facing the exhaust port 12. The backpressure baffle 2 is machined into a rotating curved surface (such as a sphere) with a certain curvature, the curvature of which can be adjusted according to actual operating conditions to match the exhaust characteristics of different engines. The curved surface allows some of the fresh combustible mixture to diffuse back and be re-drawn into the cylinder in the next intake stroke of the internal combustion engine.

[0085] Please see Figure 5 In some embodiments, the first noise-absorbing baffle 31 is a curved surface protruding towards the back pressure baffle 2, with the convex surface facing the back pressure baffle 2 and the concave surface facing the exhaust port 12. This structure causes the exhaust through-hole array on it to move backward relative to the planar first noise-absorbing baffle 31, that is, to move away from the back pressure baffle 2, thereby lengthening the airflow path of the exhaust through-hole array between the back pressure baffle 2 and the first noise-absorbing baffle 31, enhancing the reflection and interference of exhaust gas between the two, and thus further improving the noise reduction performance of the exhaust device.

[0086] In some embodiments, the first sound-absorbing baffle 31 may be a planar plate, placed radially or obliquely along the pipe body 1. Alternatively, the first sound-absorbing baffle 31 may be a curved surface convex toward the rear end of the pipe body 1, as shown in the following structure. Figure 4 As shown, this design can shorten the length of the exhaust device compared to the design with a curved surface protruding towards the back pressure baffle 2.

[0087] Please see Figure 2In some embodiments, the inner wall 16 at the front end of the tube is a curved surface that protrudes towards the air inlet 11, with the concave side of the curved surface facing the back pressure baffle 2. Combined with the curved back pressure baffle 2, the back pressure chamber 13 forms a capsule shape, which helps to establish a more stable back pressure environment.

[0088] To meet the noise reduction requirements and manufacturing feasibility under different working conditions, the exhaust vents on the baffle (including the back pressure baffle 2 and the sound-absorbing baffle) described in this application can adopt the following three structural forms, which will be described in detail below.

[0089] Please see Figures 5 to 8 In the first structural form, the back pressure baffle 2 and / or the sound-absorbing baffle includes a plate body 42 and a plurality of protrusions 43. The plate body 42 has a first exhaust hole 44, and the protrusions 43 have a second exhaust hole 45. The protrusions 43 are fixed on the plate body 42 and the second exhaust hole 45 communicates with the first exhaust hole 44 to form an exhaust through hole 41. One first exhaust hole 44 corresponds to one protrusion 43. Figures 5 to 8 The exhaust vent structure on the backpressure baffle 2 is shown. The exhaust vent structure on the sound-absorbing baffle is the same and will not be shown in an enlarged view. Since the baffle has multiple exhaust vents 41, there are multiple protrusions 43. These protrusions 43 can be fixed to the plate body 42 by welding, snap-fitting, riveting, etc. The protrusions 43 have a certain length and protrude from the surface of the plate body 42. Airflow passes through the protrusions 43, enhancing energy consumption and further attenuating sound energy. This method has a superior noise reduction effect. Preferably, the protrusions 43 on the backpressure baffle 2 are at the rear end of the backpressure baffle 2, and the protrusions 43 on the sound-absorbing baffle are at the front end of the sound-absorbing baffle.

[0090] The protrusion 43 is a hollow annular structure. An annular groove can be provided on the plate 42 to fix the protrusion 43. The annular groove surrounds the first vent hole 44. The protrusion 43 can be placed into the annular groove 46 and welded to achieve the assembly of the protrusion 43 and the plate 42. The first vent hole 44 and the second vent hole 45 together form the vent hole 41. In some embodiments, the protrusion can be fixed to the inner wall of the first vent hole. In this case, the first vent hole is only used to support the protrusion 43 and is not part of the vent hole 41. In this case, the protrusion 43 serves as the vent hole 41.

[0091] In the first structural form, the distance between the two partitions is generally 15mm (length unit, millimeter), so the depth of the exhaust hole 41 is 8 to 10mm, which can be 8mm, 8.5mm, 9mm, 10mm, etc., which not only has a certain degree of noise reduction effect, but also controls the overall length.

[0092] Please see Figure 4 In the second structural form, the exhaust holes 41 located on the partitions (backpressure partition 2 and / or sound-absorbing partitions) are formed by stamping a predetermined area on the partitions. Similarly, the exhaust holes 41 on the backpressure partitions 2 and / or the sound-absorbing partitions are formed by stamping the backpressure partitions 2 and / or the sound-absorbing partitions. The exhaust holes 41 on the backpressure partition 2 are formed by stamping the backpressure partition, and then the stamped portion completely separates from the backpressure partition, forming an exhaust hole 41 at the stamped location. Likewise, the exhaust holes 41 on the sound-absorbing partitions are formed by stamping the sound-absorbing partition, and then the stamped portion completely separates from the sound-absorbing partition, forming an exhaust hole 41 at the stamped location.

[0093] Please see Figure 9 and Figure 10 In the third structural form, the perforated plate 5 on the backpressure baffle 2 and / or the sound-absorbing baffle is bent toward the rear or front end of the pipe body 1, so that the exhaust through-hole 41 is formed at the position of the perforated plate 5 corresponding to the backpressure baffle 2 and / or the sound-absorbing baffle. The outer edge of the perforated plate 5 is adapted to the inner edge of the exhaust through-hole 41, and the perforated plate 5 is connected to the backpressure baffle 2 and / or the sound-absorbing baffle through the connecting part 51. The perforated plate 5 is originally part of the baffle. It can be bent toward the rear or front end of the pipe body 1 through a stamping process, thereby forming the exhaust through-hole 41 at that position. The perforated plate 5 is not completely separated from the baffle, but is kept connected to the baffle through the connecting part 51. The connecting part 51 is part of the plate body and is the boundary between the body and the perforated plate. Generally, the outer edge of the perforated plate 5 and the inner edge of the exhaust through-hole 41 have the same shape and are adapted to each other. However, in some embodiments, the perforated plate 5 can be trimmed to change its edge shape to adapt to different airflow disturbance design requirements. Located near the exhaust port 41, the perforated plate 5 can disturb the airflow as it passes through. When the airflow impacts the surface of the perforated plate 5, its direction is deflected, thereby enhancing energy dissipation, further weakening sound energy, and improving noise reduction performance.

[0094] Preferably, the perforated plate 5 is located at the rear end of the tube body 1. Figure 9 The perforations on the back pressure baffle 2 and the sound-absorbing baffle are shown to face the rear end of the pipe body. After the exhaust gas passes through the exhaust port, it hits the perforation 5 and some of the sound energy is consumed.

[0095] Under ideal conditions, the first and third structural forms have better noise reduction performance, while the second structural form has the weakest noise reduction effect.

[0096] Please see Figure 1 , Figure 2 , Figure 11 and Figure 14In some embodiments, the exhaust port 12 is disposed on the exhaust pipe 15, which extends from the rear end of the pipe body 1 into the silencing chamber 14, extending the exhaust path and allowing the airflow to stay in the last space of the silencing chamber 14 for a longer period of time, resulting in a better noise reduction effect. Preferably, the exhaust pipe 15 can be positioned very close to the piece of the silencing baffle assembly 3 closest to the exhaust port 12, for example... Figure 11 The exhaust pipe 15 extends from the rear into the concave surface of the curved fourth noise-reducing baffle 34, causing the airflow to bounce multiple times in this area, achieving more effective noise cancellation.

[0097] In some embodiments, to avoid poor exhaust due to excessively small through holes, the area of ​​the exhaust through hole array 4 is 550–935 mm². 2 (Area unit, square millimeters), the diameter of a single exhaust port 41 is 5-10 mm. This structure allows the exhaust gas after combustion to be discharged through the exhaust port 12 in a timely manner, avoiding excessive accumulation in the pipe body 1 and affecting the power of the internal combustion engine. The total area of ​​the exhaust port array 4 can be set to several different values ​​according to actual needs, such as 220 mm². 2 300mm 2 500mm 2 935mm 2 Meanwhile, the diameter of a single exhaust port 41 can also be selected according to the specific application, such as 5mm, 8mm, 10mm, etc.

[0098] Please see Figures 2 to 5 In some embodiments, to ensure that the total area of ​​the exhaust through-hole array is large enough, when the exhaust through-hole array is close to the center of the partition and space is limited, a multi-ring arrangement can be used to increase the number of through-holes and the total flow area, for example... Figures 2 to 5 All of them exhibit a two-ring array of exhaust vents.

[0099] In some embodiments, the center distance between two adjacent exhaust port arrays in the radial direction of the pipe body 1 is 0.35R to 0.6R, where R is the distance from the center of the baffle to its outer perimeter. When the baffle is circular, R corresponds to its radius. The following description of the embodiments also uses the radius R as an example. The center distance refers to the distance between the center of one exhaust port and the center of another exhaust port, which are located in the same radial direction of the pipe body 1. The ratio of this center distance to the baffle radius can be set to several different values ​​according to actual needs, such as 0.35, 0.42, 0.56, 0.6, etc. A larger radial offset makes the exhaust gas path longer, the energy dissipation more complete, and the noise reduction effect better.

[0100] Taking the exhaust port array 4 of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32 as an example, Figure 12This is a superimposed projection of the exhaust hole array 4 of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32. The projection direction is the pipe axis. The exhaust hole array 4 on the first noise-absorbing baffle 31 is inside the exhaust hole array 4 on the second noise-absorbing baffle 32. The radius R of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32 is 74.5 mm. The exhaust hole array of the first noise-absorbing baffle 31 is close to the center of the baffle. One of the exhaust holes e1 on the first noise-absorbing baffle 31 has a radius r1 of 33 mm. The exhaust hole array of the second noise-absorbing baffle 32 is close to the outer periphery of the baffle. One of the exhaust holes e2 on the second noise-absorbing baffle 32 has a radius r2 of 65 mm. The center distance d1 between exhaust holes e1 and exhaust holes e2 is 32 mm, corresponding to 0.42R.

[0101] Taking the exhaust port array of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32 as an example, Figure 13 This is a superimposed projection of the exhaust hole array 4 of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32. The projection direction is the pipe axis. The exhaust hole array 4 on the first noise-absorbing baffle 31 is inside the exhaust hole array 4 on the second noise-absorbing baffle 32. The radius R of the first noise-absorbing baffle 31 and the second noise-absorbing baffle 32 is 74.5 mm. The exhaust hole array of the first noise-absorbing baffle 31 is close to the center of the baffle. One of the exhaust holes e3 on the first noise-absorbing baffle 31 has a radius r3 of 23.5 mm. The exhaust hole array of the second noise-absorbing baffle 32 is close to the outer periphery of the baffle. One of the exhaust holes e2 on the second noise-absorbing baffle 32 has a radius r4 of 65 mm. The center distance d2 between exhaust holes e3 and exhaust holes e2 is 41 mm, corresponding to 0.56R.

[0102] In some embodiments, the exhaust port 41 can be designed in various shapes, including but not limited to round holes, square holes, or other geometric shapes (such as triangles, polygons, etc.), for example Figures 2 to 5 , Figures 9 to 13 The exhaust vents 41 shown are all round.

[0103] The following are several different embodiments of the exhaust device for your reference:

[0104] Example 1

[0105] Please see Figure 5 , Figure 11 , Figure 14 and Figure 15Along the direction from the air inlet 11 to the exhaust outlet 12, there are four noise-absorbing baffles: the first noise-absorbing baffle 31, the second noise-absorbing baffle 32, the third noise-absorbing baffle 33, and the fourth noise-absorbing baffle 34. The exhaust hole arrays on the four noise-absorbing baffles and the back pressure baffle 2 are all circular. The exhaust hole arrays on the back pressure baffle 2 are arranged as follows: the exhaust hole array on the first noise-absorbing baffle 31 is close to the center of the baffle and has two rings; the exhaust hole array on the second noise-absorbing baffle 32 is close to the outer periphery of the baffle; the exhaust hole array on the third noise-absorbing baffle 33 is close to the center of the baffle and has two rings; and the exhaust hole array on the fourth noise-absorbing baffle 34 is close to the outer periphery of the baffle. The exhaust holes on the back pressure baffle 2 and the noise-absorbing baffles are all structures consisting of a plate body 42 plus a protrusion 43. The distance between two noise-absorbing baffles is approximately 15 mm, and the depth of the exhaust hole 41 formed by the protrusion 43 and the plate body 42 is 8–10 mm. The thickness of plate 42 is 0.5–1 mm, which allows the exhaust device to maintain an appropriate weight. Excessive thickness will increase the weight of the exhaust device.

[0106] The backpressure baffle 2 has a curved surface protruding towards the first silencing baffle 31. The first silencing baffle 31 also has a curved surface protruding towards the backpressure baffle 2. The second silencing baffle 32 also has a curved surface protruding towards the backpressure baffle 2 and is mirror-symmetrical to it. The subsequent silencing baffles have the same structure. The structure of the silencing baffles is the same as that of the backpressure baffle 2, which facilitates manufacturing and replacement. The exhaust pipe 15 located at the rear end extends into the last silencing baffle.

[0107] Example 2

[0108] Please see Figure 2 , Figure 3 and Figure 4 The difference between Embodiment 2 and Embodiment 1 is that the number of sound-absorbing baffles is different, the orientation of the curved surface is different, and the structure of the exhaust port 41 is different.

[0109] Five noise-absorbing baffles are arranged sequentially from the air inlet 11 to the exhaust outlet 12: the first noise-absorbing baffle 31, the second noise-absorbing baffle 32, the third noise-absorbing baffle 33, the fourth noise-absorbing baffle 34, and the fifth noise-absorbing baffle 35. The exhaust hole array on the five noise-absorbing baffles and the back pressure baffle 2 is in a circular array. The internal and external arrangement of the exhaust hole array 4 between the back pressure baffle 2 and the fourth noise-absorbing baffle 34 is the same as in Embodiment 1. The fifth noise-absorbing baffle 35, which is additional in Embodiment 1, has its exhaust hole array 4 located on the inner side of the fourth noise-absorbing baffle 34.

[0110] The sound-absorbing baffle is not a curved surface protruding towards the back pressure baffle 2, but a curved surface protruding towards the inner wall 17 at the rear end of the pipe. This structure can shorten the length of the exhaust device.

[0111] The exhaust holes 41 of both the back pressure baffle 2 and the sound-absorbing baffle are through holes that penetrate both sides of the baffle. The exhaust holes can be formed by stamping the baffle so that the stamped part is completely detached, or they can be formed by cutting the baffle. The thickness of the baffle is 0.5 to 1 mm, which can control the weight of the exhaust device within an appropriate range.

[0112] Example 3

[0113] Please see Figure 9 and Figure 10 The difference between Embodiment 3 and Embodiment 2 lies in the structure of the exhaust port 41. Specifically, the perforated plate 5 on the backpressure baffle 2 and / or the noise-absorbing baffle is bent towards the rear end of the pipe body 1, so that the exhaust port 41 is formed at the original position of the perforated plate 5 on the backpressure baffle 2 and / or the noise-absorbing baffle. The perforated plate 5 is connected to the backpressure baffle 2 and / or the noise-absorbing baffle via a connecting part 51. The perforated plate 5 was originally part of the baffle; it can be bent towards the rear end or front end of the pipe body 1 through a stamping or cutting process, thereby forming the exhaust port 41 at that position.

[0114] This embodiment also provides a two-stroke internal combustion engine exhaust device, which is the exhaust device described in any of the above embodiments, and the structure of the exhaust device is as follows: Figures 1 to 16 As shown.

[0115] This embodiment also provides a drone, including a two-stroke internal combustion engine exhaust device as described in any of the above embodiments, the structure of which is as follows: Figures 1 to 15 As shown.

[0116] Unmanned Aerial Vehicles (UAVs) are aircraft that fly without a pilot, using either a remote control or an autonomous flight control system. They can carry various mission payloads (such as cameras, cargo, water pipes, etc.) and can automatically return to base or be guided to land by ground control personnel after completing a specific mission.

[0117] When drones use two-stroke internal combustion engines as their power source, the exhaust noise generated during engine operation can easily interfere with the surrounding environment. To solve this problem, the inventors optimized and improved the structure of the exhaust device, resulting in the exhaust device described in this application. This device is installed on the two-stroke internal combustion engine via a special connecting accessory, connecting the air intake of the exhaust device with the exhaust port of the engine. This achieves effective exhaust while providing reasonable back pressure control for the engine, significantly reducing operating noise, and improving the environmental adaptability and user experience of the drone in various application scenarios.

[0118] Those skilled in the art should understand that although the exhaust device described in this application is illustrated with an example of a drone, its applicability is not limited to drones. This exhaust device can also be widely used in other power equipment equipped with two-stroke internal combustion engines, such as lawnmowers, motorboats, and ATVs. By reasonably adjusting the structural parameters and installation method, this device can effectively reduce engine exhaust noise and optimize back pressure control, thereby improving the operational stability and environmental adaptability of the equipment.

[0119] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A two-stroke internal combustion engine, characterized in that, The device includes a cylinder and an exhaust device, wherein the exhaust device is directly or indirectly connected to the exhaust port of the cylinder, and the exhaust device includes a pipe body, wherein an air inlet, a baffle group and an exhaust port are sequentially arranged in the exhaust direction within the pipe body. The air intake is directly or indirectly connected to the exhaust port of the cylinder of the two-stroke internal combustion engine. The baffle assembly includes a backpressure baffle and a noise-absorbing baffle assembly arranged sequentially along the exhaust direction. The noise-absorbing baffle assembly includes two or more noise-absorbing baffles. The space between the backpressure baffle and the inner wall of the front end of the pipe body forms a backpressure chamber. The front end of the pipe body is the end of the pipe body near the air inlet. The space between the backpressure baffle and the inner wall of the rear end of the pipe body forms a noise-absorbing chamber. The rear end of the pipe body is the end of the pipe body near the exhaust port of the exhaust device. Both the backpressure baffle and the noise-absorbing baffle are provided with an exhaust hole array consisting of multiple exhaust holes. The proportion of the exhaust hole arrays of the backpressure baffle and the first noise-absorbing baffle being offset in the radial direction of the pipe body is not less than 80%. The first noise-absorbing baffle is the one closest to the backpressure baffle in the noise-absorbing baffle assembly. The exhaust port of the exhaust device is used to discharge exhaust gas or to connect to an exhaust gas emission device.

2. The two-stroke internal combustion engine according to claim 1, characterized in that, The backpressure baffle and / or the sound-absorbing baffle includes a plate body and a plurality of protrusions. The plate body has a first vent hole, and the protrusions have second vent holes. The protrusions are fixed to the plate body, and the second vent hole communicates with the first vent hole to form a venting through hole. One first vent hole corresponds to one protrusion; or... The exhaust vents located on the back pressure baffle and / or the sound-absorbing baffle are formed by stamping the back pressure baffle and / or the sound-absorbing baffle; or, The perforated plates on the back pressure baffle and / or the sound-absorbing baffle are bent toward the rear or front end of the pipe body, so that the original position of the back pressure baffle and / or the sound-absorbing baffle corresponding to the perforated plates forms the exhaust passage. The outer edge of the perforated plate is adapted to the inner edge of the exhaust passage, and the perforated plate is connected to the back pressure baffle and / or the sound-absorbing baffle through a connecting part.

3. The two-stroke internal combustion engine according to claim 1, characterized in that: The exhaust hole arrays of the back pressure baffle and the first noise-absorbing baffle are offset by no less than 90% in the radial direction of the pipe body.

4. The two-stroke internal combustion engine according to claim 1, characterized in that: The exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle group are staggered in the radial direction of the pipe by no less than 80%.

5. The two-stroke internal combustion engine according to claim 4, characterized in that: The exhaust hole arrays of two adjacent sound-absorbing baffles in the sound-absorbing baffle group are staggered by no less than 80% in the circumferential direction of the pipe body.

6. The two-stroke internal combustion engine according to claim 4, characterized in that: The exhaust hole array of the back pressure baffle is positioned closer to the outer periphery of the baffle than the exhaust hole array of the first sound-absorbing baffle. The exhaust vent arrays of adjacent back pressure baffles and sound-absorbing baffles, as well as the two adjacent sound-absorbing baffles, are arranged alternately near the outer periphery of the baffles and near the center of the baffles.

7. The two-stroke internal combustion engine according to claim 6, characterized in that: The two sound-absorbing baffles placed at intervals have the same structure.

8. The two-stroke internal combustion engine according to claim 7, characterized in that: The back pressure baffle and the second sound-absorbing baffle are structurally mirror images of each other, and the second sound-absorbing baffle is the one closest to the first sound-absorbing baffle in the sound-absorbing baffle group.

9. The two-stroke internal combustion engine according to claim 1, characterized in that: The back pressure baffle is a curved surface that protrudes towards the first sound-absorbing baffle.

10. The two-stroke internal combustion engine according to claim 1, characterized in that: The first sound-absorbing baffle has a curved surface that protrudes towards the direction of the back pressure baffle.

11. The two-stroke internal combustion engine according to claim 1, characterized in that: The inner wall of the front end of the tube is a curved surface that bulges towards the air inlet.

12. The two-stroke internal combustion engine according to claim 1, characterized in that: The area of ​​the exhaust vent array is 550–935 mm². 2 The diameter of a single exhaust port is 5 to 10 mm.

13. The two-stroke internal combustion engine according to claim 1, characterized in that: The center distance between two adjacent exhaust through-hole arrays in the radial direction of the pipe body is 0.35R to 0.6R, where R is the distance from the center of the partition to the outer perimeter.

14. The two-stroke internal combustion engine according to claim 1, characterized in that: The exhaust port of the exhaust device is located on the exhaust pipe, and the exhaust pipe extends into the silencer chamber from the rear end of the pipe body.

15. An exhaust device for a two-stroke internal combustion engine, characterized in that, The exhaust device is the exhaust device according to any one of claims 1 to 14.

16. A drone, characterized in that, Including the two-stroke internal combustion engine as described in any one of claims 1 to 14.

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