An engine scavenging system and engine

Abstract

The utility model provides a kind of engine scavenging system, through the combination structure of first main scavenging passage, first vice scavenging passage, second main scavenging passage, second vice scavenging passage and air inlet passage, and through the design of first main scavenging outlet, first vice scavenging outlet, second main scavenging outlet, second vice scavenging outlet shape, position and jet angle and the smooth transition design of unique first expansion then compression of air passage cavity, realize the acceleration replacement of scavenging airflow from bottom to top, strengthen scavenging flow rate, increase scavenging area and then realize the exhaust gas replacement of dead angle position such as combustion chamber area, improve scavenging efficiency, improve the fuel utilization of two-stroke engine, and improve tail gas emission.

Description

Technical Field

[0001] This utility model relates to the field of engine technology, and in particular to an engine scavenging system and an engine. Background Technology

[0002] An engine is the power output device of an aircraft, and small piston-type aircraft engines are the main power units used in military and civilian low-speed aircraft. In recent years, with the development of small aircraft and drones, heavy oil piston engines will inevitably become the preferred power unit for low-speed aircraft.

[0003] Traditional two-stroke piston engines consist of a crankcase and cylinders. The crankcase houses the crankshaft, the piston reciprocates within the cylinders, and connecting rods connect the crankshaft and piston. The crankcase and cylinders are connected by a combustion chamber passage, and the cylinders also have exhaust passages. In this configuration, the concentration of combustion gases in the crankcase and cylinders is the same. As the piston moves upward, the combustion gases in the cylinder are ignited. The piston then moves downward. When the piston's opening section passes through the combustion chamber passage and reaches the combustion port of the cylinder, combustion gases are injected into the cylinder through the combustion port. The new combustion gases compress the exhaust gases, causing them to be expelled through the exhaust system. This process is called scavenging. Currently, in this mode, the exhaust gas discharge rate in the combustion chamber is low, meaning the scavenging quality is poor. Low scavenging efficiency affects the intake of fresh air-fuel mixture, leading to incomplete combustion and impacting engine performance. Furthermore, scavenging short-circuiting can occur, causing fresh air-fuel mixture to be directly discharged with the exhaust gases, polluting the environment and increasing fuel consumption.

[0004] Therefore, it is necessary to provide an engine scavenging system and an engine to overcome the aforementioned defects. Utility Model Content

[0005] The purpose of this invention is to provide an engine scavenging system and an engine.

[0006] According to one aspect of the present invention, an engine scavenging system is provided, comprising:

[0007] The cylinder block includes a combustion chamber located at the top and an intake manifold, a first intake manifold group, a second intake manifold group, and an exhaust manifold arranged around the periphery of the cylinder block. The exhaust manifold is arranged opposite to the intake manifold, and the first intake manifold group and the second intake manifold group are symmetrically arranged about the vertical center plane P of the exhaust manifold.

[0008] Piston, the piston being disposed within the cylinder body;

[0009] The crankcase includes a cylinder block mounted on it, a piston connected to an internal crankshaft, and an intake manifold, a first intake manifold assembly, and a second intake manifold assembly, all of which connect to the combustion chamber and the crankcase.

[0010] The first air passage group includes a first main scavenging air passage and a first auxiliary scavenging air passage arranged adjacent to each other. The second air passage group includes a second main scavenging air passage and a second auxiliary scavenging air passage arranged adjacent to each other. The inner wall of the cylinder is provided with a first main scavenging air outlet communicating with the first main scavenging air passage, a first auxiliary scavenging air outlet communicating with the first auxiliary scavenging air passage, a second main scavenging air outlet communicating with the second main scavenging air passage, a second auxiliary scavenging air outlet communicating with the second auxiliary scavenging air passage, an intake air outlet communicating with the intake passage, and an exhaust air inlet communicating with the exhaust passage.

[0011] The upper edge of the intake outlet is lower than the upper edge of the exhaust inlet. The first auxiliary scavenging outlet and the second auxiliary scavenging outlet are located on both sides of the intake outlet. The first main scavenging outlet and the second main scavenging outlet are located on both sides of the exhaust inlet. The upper edges of the first main scavenging outlet and the second main scavenging outlet are lower than the upper edge of the exhaust inlet. The first main scavenging outlet and the first auxiliary scavenging outlet are arranged spirally upward from the exhaust inlet to the intake outlet. The second main scavenging outlet and the second auxiliary scavenging outlet are arranged spirally upward from the exhaust inlet to the intake outlet.

[0012] Preferably, the upper edges of the first main scavenging outlet and the first auxiliary scavenging outlet both extend upward along the inner wall of the cylinder, and the highest point of the upper edge of the first main scavenging outlet is lower than the lowest point of the upper edge of the first auxiliary scavenging outlet. The lower edges of the first main scavenging outlet and the first auxiliary scavenging outlet both extend upward along the inner wall of the cylinder, and the highest point of the lower edge of the first main scavenging outlet is lower than the lowest point of the lower edge of the first auxiliary scavenging outlet.

[0013] Preferably, the intake outlet, exhaust inlet, first main scavenging outlet, first auxiliary scavenging outlet, second main scavenging outlet and second auxiliary scavenging outlet are all located in the middle of the cylinder block. The bottom of the cylinder block is provided with a first scavenging inlet communicating with the first air passage group, a second scavenging inlet communicating with the second air passage group and an intake inlet communicating with the intake passage. The exhaust outlet is located on the side of the cylinder block.

[0014] Preferably, the air intake is downwardly oriented and has an opening that communicates with the inside of the cylinder; the first scavenging inlet is downwardly oriented and has an opening that communicates with the inside of the cylinder; the second scavenging inlet is downwardly oriented and has an opening that communicates with the inside of the cylinder.

[0015] Preferably, the first main scavenging passage includes a scavenging rising section extending upward from the first scavenging inlet and a scavenging inclined section extending from the scavenging rising section into the cylinder body, and a rounded scavenging transition section is provided at the connection between the scavenging rising section and the scavenging inclined section.

[0016] Preferably, the scavenging inclined section extends upward from the scavenging transition section and also extends in the direction of the air inlet outlet.

[0017] Preferably, the internal space of the first main scavenging passage gradually expands and then gradually contracts from the first scavenging inlet to the first main scavenging outlet.

[0018] Preferably, the intake duct includes an intake rising section extending upward from the intake inlet and an intake tilting section extending from the intake rising section into the cylinder body, wherein the tilting angle of the intake tilting section is α, and 60°≤α≤90°.

[0019] Preferably, the space within the air intake gradually decreases from the air inlet to the air outlet.

[0020] Preferably, the air intake includes a first air intake and a second air intake arranged adjacent to each other. The first air intake and the second air intake have the same structure, and a reinforcing rib is provided between the first air intake and the second air intake.

[0021] Preferably, the edges of the first main scavenging inlet, the first auxiliary scavenging inlet, the second main scavenging inlet, the second auxiliary scavenging inlet, the air inlet outlet, and the exhaust inlet are all provided with rounded corners.

[0022] According to another aspect of the present invention, an engine is provided, including the engine scavenging system described above.

[0023] Compared with the prior art, the engine scavenging system and engine provided by this utility model have the following beneficial effects:

[0024] Due to the adoption of the above technical solution, this utility model has the advantages of simple structure, ingenious design and low cost. By setting up a combination structure of a first main scavenging air passage, a first secondary scavenging air passage, a second main scavenging air passage, a second secondary scavenging air passage and an intake passage, and by designing the shape, position and jet angle of the first main scavenging air outlet, the first secondary scavenging air outlet, the second main scavenging air outlet and the second secondary scavenging air outlet, as well as the unique smooth transition design of the air passage cavity with expansion and compression, the scavenging airflow is accelerated from bottom to top, the scavenging airflow velocity is enhanced, the scavenging area is increased, and the exhaust gas in dead corners such as the combustion chamber area is replaced, thereby improving scavenging efficiency, improving the fuel utilization rate of the two-stroke engine and improving exhaust emissions. Attached Figure Description

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0026] Figure 1 This is a perspective view of the cylinder body of this utility model;

[0027] Figure 2 This is a three-dimensional sectional view of the cylinder body of this utility model;

[0028] Figure 3 This is a front view of the cylinder body of this utility model;

[0029] Figure 4 for Figure 3 A cross-sectional view of surface AA;

[0030] Figure 5 for Figure 3 A cross-sectional view of the BB side;

[0031] Figure 6 This is a top view of the cylinder body of this utility model;

[0032] Figure 7 for Figure 6 A cross-sectional view of the C-plane;

[0033] Figure 8 The cylinder body of this utility model;

[0034] Figure 9 This is a view showing the unfolded inner surface of the cylinder body of this utility model;

[0035] Figure 10 This is a schematic diagram of the scavenging airflow in the engine scavenging system of this utility model when the piston is moving downward.

[0036] Among them, A, cylinder block; 1, combustion chamber; 2, intake manifold; 21, intake outlet; 22, intake inlet; 23, intake rise section; 24, intake tilt section; 3, first intake manifold group; 31, first main scavenging manifold; 311, first main scavenging outlet; 312, scavenging rise section; 313, scavenging tilt section; 314, scavenging transition section; 315, rounded protrusion; 32, first secondary scavenging manifold; 321, first secondary scavenging outlet; 33, first scavenging inlet; 4, second intake manifold group; 41, second main scavenging manifold; 411, second main scavenging outlet; 42, second secondary scavenging manifold; 421, second secondary scavenging outlet; 43, second scavenging inlet; 5, exhaust manifold; 51, exhaust inlet; 52, exhaust outlet; 6, opening; 7, reinforcing rib; B, piston. Detailed Implementation

[0037] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] To keep the drawings concise, only the parts relevant to this invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0039] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0040] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0041] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0043] See Figure 1 and Figure 10 This embodiment discloses an engine scavenging system, including a cylinder block A, a piston B, a crankcase, and a crankshaft. The cylinder block A is fixed to the crankcase, and the two are internally connected. The piston B is located inside the cylinder block A and is connected to the crankshaft inside the crankcase.

[0044] See Figure 2 , Figure 4 and Figure 5The cylinder block A includes a combustion chamber 1 located at the top and an intake manifold 2, a first intake manifold group 3, a second intake manifold group 4, and an exhaust manifold 5 arranged around the periphery of the cylinder block A. The exhaust manifold 5 is arranged opposite to the intake manifold 2, and the first intake manifold group 3 and the second intake manifold group 4 are symmetrically arranged about the vertical center plane P of the exhaust manifold 5. The first intake manifold group 3 includes a first main scavenging manifold 31 and a first auxiliary scavenging manifold 32 arranged adjacent to each other, and the second intake manifold group 4 includes a second main scavenging manifold 41 and a second auxiliary scavenging manifold 42 arranged adjacent to each other. The intake manifold 2, the first main scavenging manifold 31, the first auxiliary scavenging manifold 32, the second main scavenging manifold 41, and the second auxiliary scavenging manifold 42 all connect to the combustion chamber 1 and the crankcase.

[0045] The inner wall of cylinder A is provided with a first main scavenging outlet 311 communicating with the first main scavenging passage 31, a first auxiliary scavenging outlet 321 communicating with the first auxiliary scavenging passage 32, a second main scavenging outlet 411 communicating with the second main scavenging passage 41, a second auxiliary scavenging outlet 421 communicating with the second auxiliary scavenging passage 42, an intake outlet 21 communicating with the intake passage 2, and an exhaust inlet 51 communicating with the exhaust passage 5. The intake outlet 21, exhaust inlet 51, first main scavenging outlet 311, first auxiliary scavenging outlet 321, second main scavenging outlet 411, and second auxiliary scavenging outlet 421 are all located in the middle of cylinder A. The upper edge of the intake outlet 21 is lower than the upper edge of the exhaust inlet 51. The first auxiliary scavenging outlet 321 and the second auxiliary scavenging outlet 421 are located on both sides of the intake outlet 21, and the first main scavenging outlet 311 and the second main scavenging outlet 411 are located on both sides of the exhaust inlet 51.

[0046] The bottom of cylinder A is provided with a first scavenging inlet 33 communicating with the first air passage group 3, a second scavenging inlet 43 communicating with the second air passage group 4, and an intake inlet 22 communicating with the intake passage 2. The exhaust outlet 52 is located on the side of cylinder A. The intake inlet 22 opens downward and has an opening 6 communicating with the interior of cylinder A; the first scavenging inlet 33 opens downward and has an opening 6 communicating with the interior of cylinder A; the second scavenging inlet 43 opens downward and has an opening 6 communicating with the interior of cylinder A.

[0047] Piston B reciprocates within cylinder A. When piston B is at bottom dead center, the piston skirt completely blocks opening 6. The first main scavenging passage 31, the first auxiliary scavenging passage 32, the second main scavenging passage 41, the second auxiliary scavenging passage 42, and the intake passage 2 all connect to the inside of the crankcase with downward-opening inlets and outlets. That is, the intake port is formed by the piston skirt and the inner walls of each passage. At this time, the surface of the piston skirt used to block opening 6 can contact the oil and gas in the crankcase, thereby increasing the contact area between the piston skirt and the oil and gas and providing more stable lubrication for the piston skirt.

[0048] During the descent of piston B, the piston skirt is partially above opening 6. At this time, the oil and gas in the crankcase enter the corresponding air passages through the downward-opening inlets or entrances of each air passage, as well as the side-penetrating opening 6, and then flow into the combustion chamber 1. Compared to existing engines with bottom-connected crankcases, this significantly increases the area of ​​the scavenging inlet, thereby increasing the intake volume per unit time and the flow velocity of oil and gas in each air passage.

[0049] See Figure 6 and Figure 7 The first main scavenging passage 31 includes a scavenging rising section 312 extending upward from the first scavenging inlet 33 and a scavenging inclined section 313 extending from the scavenging rising section 312 into the cylinder A. A rounded-corner scavenging transition section 314 is provided at the connection between the scavenging rising section 312 and the scavenging inclined section 313. The inner wall of the first scavenging passage gradually bulges outward from the inner cavity of the cylinder A, forming a rounded-corner protrusion 315 within the passage. This protrusion reduces the passage diameter, compresses the air to increase its velocity, and thus forms the scavenging transition section 314. The scavenging transition section 314 effectively reduces the air resistance of the scavenging inclined section 313 to the upward-flowing gas in the scavenging rising section 312, allowing for smooth and efficient airflow. The scavenging inclined section 313 extends upward from the scavenging transition section 314 and also extends inclined towards the direction of the intake outlet 21. Furthermore, in this embodiment, the upward scavenging angle of the relative scavenging inclined segment 313 is θ, and 156°≤θ≤168°.

[0050] See Figure 8 The internal space of the first main scavenging passage 31 gradually expands and then gradually contracts from the first scavenging inlet 33 to the first main scavenging outlet 311. This arrangement can slightly decelerate the oil-gas mixture entering the scavenging passage at high speed, enhancing the oil-gas mixing effect, and then accelerate its exit. The internal arrangement of the first auxiliary scavenging passage 32 is the same as that of the first main scavenging passage 31, and the internal arrangement of the second main scavenging passage 41 is also the same as that of the first main scavenging passage 31.

[0051] See Figure 5 The air intake duct 2 includes a first air intake duct 2a and a second air intake duct 2b arranged adjacent to each other. The first air intake duct 2a and the second air intake duct 2b have the same structure, and a reinforcing rib 7 is provided between the first air intake duct 2a and the second air intake duct 2b. A reinforcing rib 7 is provided between the first scavenging air passage and the second scavenging air passage to separate them.

[0052] See Figure 3 and Figure 4The first intake passage 2a includes an intake riser section 23 extending upward from the intake inlet 22 and an intake tilt section 24 extending from the intake riser section 23 into the cylinder block A. The tilt angle of the intake tilt section 24 is α, and 60°≤α≤90°, which can effectively prevent the swept-in oil-air mixture from being directly discharged from the exhaust inlet 51 without replacing the exhaust gas. The space within the first intake passage 2a gradually decreases from the intake inlet 22 to the intake outlet 21.

[0053] The upper edge of the exhaust inlet 51 is higher than the upper edge of the intake outlet 21. This allows the exhaust inlet 51 to open before the intake outlet 21 during the downward movement of the piston B, enabling forced exhaust and expelling some of the exhaust gas from the combustion chamber 1. This facilitates the cleaning of residual exhaust gas in the combustion chamber 1 after the intake outlet 21 and scavenging outlet are opened.

[0054] See Figure 5 The upper edges of the first main scavenging outlet 311 and the second main scavenging outlet 411 are lower than the upper edge of the exhaust inlet 51 and also lower than the upper edge of the intake outlet 21. The first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 are arranged spirally upward from the exhaust inlet 51 to the intake outlet 21, and the second main scavenging outlet 411 and the second auxiliary scavenging outlet 421 are also arranged spirally upward from the exhaust inlet 51 to the intake outlet 21. The lateral scavenging angles between the first and second main scavenging outlets are b and c, respectively, where 110°≤b≤120° and 135°≤c≤145°; the lateral scavenging angles between the first main and auxiliary outlets and the second auxiliary scavenging outlet are d and e, respectively, where 140°≤d≤150° and 155°≤e≤160°. These angles together constitute the lateral scavenging area.

[0055] During the downward movement of piston B, the intake outlet 21, the first auxiliary scavenging outlet 321, and the first main scavenging outlet 311 are opened sequentially to drive the exhaust gas towards the exhaust inlet 51 and discharge it from a distance using scavenging gas. During the scavenging process, scavenging begins first at the intake outlet 21, which is furthest from the exhaust inlet 51. Then, the first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 are opened sequentially, driving the exhaust gas in the combustion chamber 1 towards the exhaust port in a step-by-step manner.

[0056] See Figure 4The upper edges of both the first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 extend upwards along the inner wall of cylinder A, with the highest point of the upper edge of the first main scavenging outlet 311 being lower than the lowest point of the upper edge of the first auxiliary scavenging outlet 321. Similarly, the lower edges of both the first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 extend upwards along the inner wall of cylinder A, with the highest point of the lower edge of the first main scavenging outlet 311 being lower than the lowest point of the lower edge of the first auxiliary scavenging outlet 321. This configuration controls the gradual upward shift of the scavenging airflow during piston B's downward movement. In actual engine operation, the scavenging speed is very high, and the exchange time is very short. If the scavenging airflow is always kept directly connected to the exhaust port, the airflow speed will be the highest, resulting in the exhaust gas in combustion chamber 1 being unable to escape. If the scavenging airflow is always kept flowing upwards along the cylinder wall to combustion chamber 1 and then out towards the exhaust port, the scavenging path becomes longer, and the exhaust gas in the lower part of the cylinder will not be able to escape smoothly due to the spiral action. Therefore, when the scavenging port is first opened, the middle and lower regions are replaced first. As the scavenging port is continuously enlarged, the fresh airflow is continuously increased and the airflow direction is continuously adjusted upward. At the same time, it merges with the mixed oil and gas flowing out of the air inlet 21 and gives the gas flowing out of the air inlet 21 an upward thrust, causing the merged gas to flow upward, further replacing the exhaust gas in the middle and upper regions, which is more conducive to improving the scavenging efficiency.

[0057] See Figure 9 Preferably, in this embodiment, the upper edges of the first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 are on the same upward-sloping straight line L1. The lower edges of the first main scavenging outlet 311 and the first auxiliary scavenging outlet 321 are on the same upward-sloping straight line L2. The angle between L1 and the horizontal straight line L is f, and 3°≤f≤6°; the angle between L2 and the horizontal straight line L is g, and 2°≤g≤4.5°, and f≥g.

[0058] In other embodiments, the upper edges of the first main scavenging outlet 311 and the first secondary scavenging outlet 321 both extend upward along the inner wall of cylinder A, and the highest point of the upper edge of the first main scavenging outlet 311 is lower than the lowest point of the upper edge of the first secondary scavenging outlet 321. The lowest points of the lower edges of the first main scavenging outlet 311, the second main scavenging outlet 411, the lower edge of the intake outlet 21, and the lower edge of the exhaust inlet 51 are at the same or substantially the same height.

[0059] All scavenging outlets, intake outlets 21, and exhaust inlets 51 have rounded edges of less than 1mm. This not only prevents piston rings from jamming due to abrupt changes in cross-section, but also creates a smooth transition in the flow cross-section when each port first opens, avoiding a sudden decrease in airflow velocity caused by abrupt changes in cross-section. Furthermore, each outlet has a constricted design to enhance airflow velocity.

[0060] The two-stroke engine primarily achieves its pumping function through the up-and-down movement of piston B. The rotation of the crankshaft within the engine drives piston B to reciprocate within cylinder A, thereby controlling the opening and closing of the intake outlet 21, exhaust inlet 51, and various scavenging outlets. The spatial arrangement of the intake manifold and the design of the scavenging outlets' fit with the top of piston B enhance scavenging efficiency, resulting in better combustion efficiency.

[0061] See Figure 10 The specific scavenging process is as follows: After the combustible air-fuel mixture undergoes deflagration and expansion in combustion chamber 1, it pushes piston B downwards. During piston B's downward movement, the exhaust port opens first, allowing some high-pressure exhaust gas to escape. Subsequently, intake outlet 21 opens for rapid scavenging. To prevent short-circuiting of the combustible mixture, as piston B continues to move downwards, the auxiliary scavenging outlet and the main scavenging outlet open sequentially. The main scavenging outlet removes the exhaust gas in front of the scavenging airflow at intake outlet 21 and merges with it, pushing it upwards. The auxiliary scavenging outlet removes the exhaust gas in front of the main scavenging airflow and merges with it, pushing it upwards. Scavenging proceeds to the middle and upper parts of combustion chamber 1, further replacing the exhaust gas in the dead zones of combustion chamber 1. Furthermore, the main and auxiliary air passages have an expansion-then-contraction structure, allowing the main and auxiliary scavenging airflows to move towards the top of combustion chamber 1 at a faster flow rate, improving the scavenging conversion efficiency. At the same time, as piston B moves downward, it also compresses the oil-air mixture in the crankcase, causing it to be blown into the combustion chamber 1 through the intake manifold 2 and the main and auxiliary scavenging manifolds.

[0062] This embodiment also discloses an engine including the aforementioned engine scavenging system. By rationally designing the angles, chord lengths, and heights of the two crossflow scavenging ports and four return flow scavenging ports, the scavenging area of ​​the exhaust gas is increased, thus allowing for the intake of more fresh air-fuel mixture. This accelerates the exhaust gas emission speed, significantly improving the engine's flow coefficient and power. Simultaneously, it reduces exhaust pollution during engine operation, resulting in greater energy efficiency and environmental friendliness.

[0063] It will be apparent to those skilled in the art that various modifications and variations can be made to the exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention cover modifications and variations falling within the scope of the appended claims and their equivalents.

Claims

1. An engine scavenging system, characterized in that, include: The cylinder block includes a combustion chamber located at the top and an intake manifold, a first intake manifold group, a second intake manifold group, and an exhaust manifold arranged around the periphery of the cylinder block. The exhaust manifold is arranged opposite to the intake manifold, and the first intake manifold group and the second intake manifold group are symmetrically arranged about the vertical center plane P of the exhaust manifold. Piston, the piston being disposed within the cylinder body; The crankcase includes a cylinder block mounted on it, a piston connected to an internal crankshaft, and an intake manifold, a first intake manifold assembly, and a second intake manifold assembly, all of which connect to the combustion chamber and the crankcase. The first air passage group includes a first main scavenging air passage and a first auxiliary scavenging air passage arranged adjacent to each other. The second air passage group includes a second main scavenging air passage and a second auxiliary scavenging air passage arranged adjacent to each other. The inner wall of the cylinder is provided with a first main scavenging air outlet communicating with the first main scavenging air passage, a first auxiliary scavenging air outlet communicating with the first auxiliary scavenging air passage, a second main scavenging air outlet communicating with the second main scavenging air passage, a second auxiliary scavenging air outlet communicating with the second auxiliary scavenging air passage, an intake air outlet communicating with the intake passage, and an exhaust air inlet communicating with the exhaust passage. The upper edge of the intake outlet is lower than the upper edge of the exhaust inlet. The first auxiliary scavenging outlet and the second auxiliary scavenging outlet are located on both sides of the intake outlet. The first main scavenging outlet and the second main scavenging outlet are located on both sides of the exhaust inlet. The upper edges of the first main scavenging outlet and the second main scavenging outlet are lower than the upper edge of the exhaust inlet. The first main scavenging outlet and the first auxiliary scavenging outlet are arranged spirally upward from the exhaust inlet to the intake outlet. The second main scavenging outlet and the second auxiliary scavenging outlet are arranged spirally upward from the exhaust inlet to the intake outlet.

2. The engine scavenging system as described in claim 1, characterized in that, The upper edges of the first main scavenging outlet and the first auxiliary scavenging outlet both extend upward along the inner wall of the cylinder, and the highest point of the upper edge of the first main scavenging outlet is lower than the lowest point of the upper edge of the first auxiliary scavenging outlet. The lower edges of the first main scavenging outlet and the first auxiliary scavenging outlet both extend upward along the inner wall of the cylinder, and the highest point of the lower edge of the first main scavenging outlet is lower than the lowest point of the lower edge of the first auxiliary scavenging outlet.

3. The engine scavenging system as described in claim 2, characterized in that, The intake outlet, exhaust inlet, first main scavenging outlet, first auxiliary scavenging outlet, second main scavenging outlet and second auxiliary scavenging outlet are all located in the middle of the cylinder block. The bottom of the cylinder block is provided with a first scavenging inlet connected to the first air passage group, a second scavenging inlet connected to the second air passage group and an intake inlet connected to the intake passage. The exhaust outlet is located on the side of the cylinder block.

4. The engine scavenging system as described in claim 3, characterized in that, The air intake is downward-facing and has an opening that communicates with the inside of the cylinder; the first scavenging inlet is downward-facing and has an opening that communicates with the inside of the cylinder; the second scavenging inlet is downward-facing and has an opening that communicates with the inside of the cylinder.

5. The engine scavenging system as described in claim 4, characterized in that, The first main scavenging passage includes a scavenging rising section extending upward from the first scavenging inlet and a scavenging inclined section extending from the scavenging rising section into the cylinder body. A rounded scavenging transition section is provided at the connection between the scavenging rising section and the scavenging inclined section.

6. The engine scavenging system as described in claim 5, characterized in that, The scavenging inclined section extends upward from the scavenging transition section and also extends in the direction of the air inlet outlet.

7. The engine scavenging system as described in claim 6, characterized in that, The internal space of the first main scavenging passage gradually expands and then gradually contracts from the first scavenging inlet to the first main scavenging outlet.

8. The engine scavenging system as described in claim 7, characterized in that, The intake duct includes an intake rising section extending upward from the intake inlet and an intake tilting section extending into the cylinder body from the intake rising section. The tilting angle of the intake tilting section is α, where 60°≤a≤90°.

9. The engine scavenging system as described in claim 8, characterized in that, The space within the air intake gradually decreases from the air inlet to the air outlet.

10. The engine scavenging system as described in claim 9, characterized in that, The air intake includes a first air intake and a second air intake arranged adjacent to each other. The first air intake and the second air intake have the same structure, and a reinforcing rib is provided between the first air intake and the second air intake.

11. The engine scavenging system as described in claim 10, characterized in that, The edges of the first main scavenging inlet, the first auxiliary scavenging inlet, the second main scavenging inlet, the second auxiliary scavenging inlet, the air inlet outlet, and the exhaust inlet are all rounded.

12. An engine, characterized in that, The engine scavenging system includes any one of claims 1 to 11.

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