Two-stroke engine exhaust gas recirculation system device and multi-cylinder two-stroke engine

Abstract

The invention provides an exhaust gas recirculation system device of a two-stroke engine, which is characterized in that a piston skirt is provided with an opening for forming an air flow channel between the inside of a crankcase and an exhaust silencer under a specific engine running state, and the exhaust silencer is communicated with the crankcase to ensure that the exhaust silencer is communicated with the crankcase in the air suction process of the engine; the exhaust gas exhausted by the adjacent cylinder can be guided into the crankcase; in the engine air suction stage, negative pressure is formed in the crankcase through ascending of the piston, an air inlet valve is opened, fresh air, fuel and waste gas are led into the crankcase to form mixed gas, and the waste gas in the mixed gas participates in the engine combustion period. By means of the technical scheme, the problems that in the prior art, a two-stroke engine is high in fuel consumption rate and poor in economical efficiency, and the combustion stability of an aviation kerosene engine is greatly affected by the cylinder temperature can be effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of internal combustion engines, and in particular to an exhaust gas recirculation system device of a two-stroke engine, the engine, and a multi-cylinder two-stroke engine. Background Art

[0002] Existing two-stroke engine technologies, especially multi-cylinder two-stroke engines used in motorcycles, outboard motors, and aviation, suffer from high fuel consumption and relatively poor economy. This is mainly due to the following reasons: 1. Partial fuel emission loss: During the scavenging process of a two-stroke engine, when the new intake air pushes the exhaust gas after combustion, some of the unburned fuel will also be discharged with the exhaust gas, resulting in energy waste.

[0003] 2. Low compression ratio limitation: In order to prevent detonation, two-stroke engines usually use a lower compression ratio. The compression ratio directly affects the thermal efficiency of the engine. A low compression ratio means lower thermal efficiency, which increases fuel consumption.

[0004] 3. For two-stroke engines fueled by aviation kerosene, the volatility of aviation kerosene is far less than that of gasoline, resulting in combustion quality being heavily dependent on in-cylinder temperature or ambient temperature. Unfavorable temperature conditions can lead to combustion instability and reduced efficiency.

[0005] Existing solutions only partially address these issues and fail to fully optimize overall engine performance. Therefore, finding a technical solution that can effectively reduce the risk of explosion, increase the compression ratio without adding additional complexity, and improve the combustion stability of aviation kerosene engines has become a key technical challenge that needs to be addressed. Summary of the Invention

[0006] The present invention provides a two-stroke engine exhaust gas recirculation system, comprising a special piston with a custom-designed opening in its skirt. Under specific engine operating conditions, this opening forms an airflow channel between the crankcase interior and the exhaust muffler, allowing exhaust gas discharged from adjacent cylinders into the exhaust muffler to be introduced into the engine for combustion. The two-stroke engine exhaust gas recirculation system and its operating process are as follows: M1: Compression and intake, including: the engine piston with a custom opening on the piston skirt of the engine cylinder moves upward from the bottom dead center, the piston compresses the combustion chamber space and fuel, and a negative pressure is formed in the crankcase. At this time, the scavenging duct is closed and the intake valve is opened. The airflow introduction mechanism thus formed draws fresh air and fuel into the crankcase from the intake port. When the piston moves up to near the top dead center, the custom-designed opening on the piston skirt is connected to the exhaust muffler through the exhaust duct. For most multi-cylinder two-stroke engines, especially in-line two-cylinder and horizontally opposed four-cylinder two-stroke engines, when the current cylinder is inhaling, the adjacent cylinder is exhausting. Therefore, the negative pressure inside the crankcase causes the exhaust gas discharged into the exhaust muffler by the adjacent cylinder to be sucked into the crankcase through the exhaust duct and the opening designed in the piston skirt, forming a mixture mainly composed of fresh air, fuel and exhaust gas inside the crankcase. M2: Work and ventilation, including: the engine cylinder piston moves upward to the top dead center, the fuel in the combustion chamber is compressed to an ignitable state, the spark plug ignites the fuel in the combustion chamber, and the fuel combustion and expansion push the piston downward to perform work. At this time, the intake valve closes, and a portion of the exhaust gas after the fuel combustion is discharged through the exhaust duct. The opening designed in the piston skirt is offset and closed with the exhaust duct. The piston moves downward to compress the mixture mainly composed of fresh air, fuel and exhaust gas in the crankcase; when the piston moves downward to near the bottom dead center, the scavenging duct opens and connects to the combustion chamber and the exhaust duct. The compressed mixture in the crankcase flows into the combustion chamber through the opened scavenging duct, sweeping the remaining exhaust gas in the combustion chamber to the outside through the exhaust duct, completing the ventilation. The exhaust gas discharged and swept to the outside both enter the exhaust muffler (when the adjacent cylinder enters the compression intake stroke again, the exhaust gas will be re-inhaled into the crankcase of the adjacent cylinder through the exhaust gas recirculation device of the adjacent cylinder); M3: The exhaust gas in the mixture participates in the combustion, including: the engine cylinder piston rises again from the bottom dead center, the combustion chamber space and the mixture mainly composed of fresh air, fuel and exhaust gas remaining in the combustion chamber are compressed by the ascending piston, and negative pressure is formed in the crankcase again. At this time, the scavenging duct is closed again, and the intake valve is opened again. The air flow introduction mechanism allows the crankcase to inhale new fresh air and fuel through the intake valve again. When the piston rises to near the top dead center, the custom-designed opening on the piston skirt is connected to the exhaust muffler again through the exhaust duct, and the exhaust gas discharged into the exhaust muffler from the adjacent cylinder is inhaled again. A new mixture composed of fresh air, fuel, exhaust gas, etc. is formed inside the crankcase; when the piston rises to the top dead center, the original mixture is compressed to the ignition state The spark plug ignites the original mixture, and the original mixture burns and expands to push the piston down again to do work. At this time, the intake valve is closed again, and a part of the exhaust gas after the original mixture is burned is discharged through the exhaust duct. The opening designed in the piston skirt and the exhaust duct are staggered and closed again, and the descending piston compresses the new mixture in the crankcase again; when the piston descends to near the bottom dead center, the scavenging duct opens and connects with the combustion chamber and the exhaust duct, and the compressed new mixture in the crankcase flows into the combustion chamber through the opened scavenging duct, and the remaining exhaust gas of the original mixture burned in the combustion chamber is swept to the outside through the exhaust duct, completing the ventilation again; the new exhaust gas discharged and swept to the outside enters the exhaust muffler again, so that the engine exhaust gas recirculation device completes a complete exhaust gas recirculation work.

[0007] Preferably, the openings designed on the piston skirt have different diameters, shapes and distribution patterns depending on the engine and are custom designed accordingly; Preferably, the connection between the crankcase and the opening designed on the piston skirt, the exhaust passage, and the exhaust muffler is formed when the piston moves upward to near the top dead center.

[0008] Preferably, the exhaust gas is mainly composed of high specific heat capacity gases such as CO2 and H2O, and the temperature is usually higher than the ambient temperature.

[0009] Preferably, the exhaust gas drawn into the crankcase preheats its mixture with fresh air and fuel.

[0010] Preferably, the system is applicable to multi-cylinder two-stroke engines, including but not limited to inline two-cylinder and horizontally opposed four-cylinder engines.

[0011] On the one hand, the present invention provides a two-stroke engine, including an engine body; a two-stroke engine exhaust gas recirculation system device as described in M1 to M3 above, which is applied to the engine body, wherein the piston skirt opening design is an integral part of the piston of the engine body, the exhaust muffler is connected to the exhaust system of the engine body, and the airflow introduction mechanism works in coordination with the intake system of the engine body.

[0012] On the one hand, the present invention provides a multi-cylinder two-stroke engine, comprising a multi-cylinder engine body; a two-stroke engine as described above, wherein the engine exhaust gas recirculation device realizes exhaust gas recirculation through the operating timing between adjacent cylinders of the multi-cylinder engine body.

[0013] The exhaust gas recirculation system of a two-stroke engine of the present invention ensures that the exhaust gas in the mixture participates in the entire combustion cycle. On the one hand, because the main components of the exhaust gas are CO2, H2O, etc., the exhaust gas has a relatively high specific heat capacity. When the exhaust gas is introduced into the crankcase and mixed with the incoming fresh air and fuel to form a mixed gas, the mixed gas has a higher specific heat capacity due to the addition of the exhaust gas. This allows the mixed gas to absorb more heat within the combustion chamber, lowering the combustion temperature and thus reducing the risk of knock. This, in turn, improves the engine's compression ratio and thermal efficiency, thereby reducing fuel consumption. On the other hand, when the engine uses aviation kerosene as fuel, the exhaust gas itself has a relatively high temperature (typically higher than the ambient temperature). Heat from the exhaust gas is transferred to the fresh air and fuel through the airflow, heating the aviation kerosene in the mixture during the mixing process, facilitating its evaporation and atomization, thereby significantly improving the combustion stability of the aviation kerosene engine. The engine exhaust gas recirculation system of the present invention allows the exhaust gas to participate in the entire engine combustion cycle, thereby achieving the effects of increasing specific heat capacity, lowering combustion temperature, improving thermal efficiency, reducing fuel consumption, and enhancing fuel combustion stability.

[0014] Beneficial effects

[0015] The exhaust gas recirculation system for a two-stroke engine of the present invention effectively improves the combustion efficiency of the two-stroke engine, reduces the risk of explosion, increases the compression ratio without adding additional complex structures, and improves the combustion stability of aviation kerosene. Specific beneficial effects are as follows: 1. Extend service life: The circulation of exhaust gas increases the specific heat capacity of the mixed gas, which means that it can absorb more heat without causing a sharp rise in temperature. During the combustion process, it helps to lower the combustion temperature, reduce heat load and thermal stress, and thus extend the service life of the engine.

[0016] 2. Reduce knock: By increasing the specific heat capacity of the mixed gas in the crankcase, the maximum temperature in the combustion chamber can be effectively reduced, reducing the possibility of knock, allowing the use of a higher compression ratio, and thus improving engine efficiency.

[0017] 3. Reduce fuel consumption: The increase in specific heat capacity means that heat energy can be better utilized during the combustion process, reducing heat loss and improving thermal efficiency. The higher the thermal efficiency of the engine, the more efficient its energy conversion is and the lower the fuel consumption is.

[0018] 4. Improved combustion stability: Exhaust gas with a higher specific heat capacity can better preheat the mixture during the compression stage, which helps with fuel atomization and mixing before combustion. This improves combustion stability, especially for aviation kerosene, which is not easy to evaporate. On the other hand, this improvement is more obvious when the engine is cold started or operating at low ambient temperatures.

[0019] 5. Reduce pollutant emissions: The exhaust gas recirculation system can recycle the unburned fuel in the exhaust gas for combustion; at the same time, the exhaust gas reduces the combustion temperature and improves the combustion stability, so the engine will produce less NO during operation. x (nitrogen oxides) and other harmful pollutants. The above combined factors are conducive to environmental protection.

[0020] 6. The exhaust gas recirculation device for a two-stroke engine of the present invention is adaptable to various types of multi-cylinder two-stroke engine layouts, ensuring the wide applicability of the system.

[0021] The present invention promotes the development of two-stroke engine technology. We have calculated through CAE simulation data that the efficiency of the exhaust gas recirculation system in the cylinder of a two-stroke engine using the present invention under normal operating conditions can reach 14%, the combustion temperature can be reduced by more than 50°C, the engine compression ratio can be increased to more than 8, and the mixture temperature in the crankcase can be increased by about 70°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the compression and intake of the exhaust gas recirculation system of a two-stroke engine; Figure 2 This is a schematic diagram of the power generation and ventilation of the exhaust gas recirculation system of a two-stroke engine; Figure 3 This is a schematic diagram of the exhaust gas recirculation system of a two-stroke engine during power generation and ventilation. Figure 4 Schematic diagram of the combustion cycle of the exhaust gas circulating in the exhaust gas recirculation system of a two-stroke engine; Figure 5 A schematic diagram of the exhaust gas circulating in the exhaust gas recirculation system of a two-stroke engine participating in the combustion cycle to perform work; Figure 6 A schematic diagram of the exhaust gas circulating in the exhaust gas recirculation system of a two-stroke engine participating in the combustion cycle scavenging; Figure 7 This is a schematic diagram of the exhaust gas recirculation system of a two-stroke engine, with cylinder A inhaling and cylinder B exchanging air. Figure 8 This is a schematic diagram of the exhaust gas recirculation system of a two-stroke engine, in which cylinder B inhales and cylinder A exhales on an in-line twin-cylinder two-stroke engine; Figure 9This is a schematic diagram of the exhaust gas recirculation system of a two-stroke engine installed on a horizontally opposed four-cylinder two-stroke engine, with cylinder 1 intake and cylinder 3 exhaust working.

[0023] Figure 10 This is a schematic diagram of the exhaust gas recirculation system of a two-stroke engine installed on cylinder 2 of a horizontally opposed four-cylinder two-stroke engine, with cylinder 4 exhausting and cylinder 4 inhaling.

[0024] Figures: A, cylinder A of an in-line two-cylinder two-stroke engine; B, cylinder B of an in-line two-cylinder two-stroke engine; G, exhaust muffler of an in-line two-cylinder two-stroke engine; 1, cylinder 1 of a horizontally opposed four-cylinder two-stroke engine; 2, cylinder 2 of a horizontally opposed four-cylinder two-stroke engine; 3, cylinder 3 of a horizontally opposed four-cylinder two-stroke engine; 4, cylinder 4 of a horizontally opposed four-cylinder two-stroke engine; 13, exhaust mufflers of cylinders 1 and 3; 18, exhaust duct; A18, exhaust duct of cylinder A; B18, exhaust duct of cylinder B; 19, scavenging duct ; A19, scavenging duct of cylinder A; B19, scavenging duct of cylinder B; 20, piston skirt; A20, piston skirt of cylinder A; B20, piston skirt of cylinder B; 21, design opening; A21, design opening of cylinder A; B21, design opening of cylinder B; 22, crankcase; A22, crankcase of cylinder A; B22, crankcase of cylinder B; 23, exhaust muffler; 24, exhaust muffler of cylinders 2 and 4; 25, intake valve; A25, intake valve of cylinder A; B25, intake valve of cylinder B; 26, piston; A26, A Cylinder piston; B26, Cylinder B piston; 27, Combustion chamber; A27, Cylinder A combustion chamber; B27, Cylinder B combustion chamber; 30, Exhaust gas; A30, Cylinder A exhaust gas; B30, Cylinder B exhaust gas; 31, Fresh air and fuel; A31, Cylinder A fresh air and fuel; B31, Cylinder B fresh air and fuel; 32, Mixture (original mixture); A32, Cylinder A mixture; B32, Cylinder B mixture; 33, Exhaust and scavenging exhaust gas; 34, New fresh air and fuel; 35, New exhaust gas; 3 6. New mixture; 37. Exhaust gas from the combustion of the original mixture; 120. Design opening of cylinder 1; 121. Piston skirt of cylinder 1; 122. Crankcase of cylinder 1; 126. Piston of cylinder 1; 131. Fresh air and fuel of cylinder 1; 230. Exhaust gas of cylinder 2; 232. Mixture of cylinder 2; 330. Exhaust gas of cylinder 3; 332. Mixture of cylinder 3; 420. Design opening of cylinder 4; 421. Piston skirt of cylinder 4; 422. Crankcase of cylinder 4; 426. Piston of cylinder 4; 431. Fresh air and fuel of cylinder 4. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by one of ordinary skill in the art to which this application belongs. In the present invention, unless otherwise specified, directional terms such as "upper, lower, top, and bottom" are generally used with respect to the directions shown in the accompanying drawings, or with respect to the components themselves in the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "inside" and "outside" refer to the inside and outside relative to the outline of each component itself, but the above directional terms are not intended to limit the present invention.

[0027] Example 1

[0028] The compression and suction working process of the exhaust gas recirculation system of a two-stroke engine, such as Figure 1 As shown: the piston 26 moves upward from the bottom dead center, compressing the fuel and space in the combustion chamber 27, forming a negative pressure in the crankcase 22. At this time, the scavenging passage 19 is closed and the intake valve 25 is opened. The gas introduction mechanism formed thereby draws in fresh air and fuel 31 from the intake port. At the same time, when the piston 26 moves upward to near the top dead center, the custom-designed opening 21 on the piston skirt 20 is connected to the exhaust muffler 23 through the exhaust passage 18; when the current cylinder is inhaling, the adjacent cylinder is exhausting, and the exhausted exhaust gas 30 is discharged into the exhaust muffler 23. At this time, the negative pressure inside the crankcase 22 of the current cylinder causes the exhaust gas 30 discharged from the adjacent cylinder into the exhaust muffler 23 to be sucked into the crankcase 22 through the exhaust passage 18 and the opening 21 designed on the piston skirt 20, thereby forming a mixture 32 consisting of fresh air, fuel 31, exhaust gas 30, etc. Figure 2 As shown; The exhaust gas recirculation system of a two-stroke engine is used for the working and ventilation process. Figure 2 As shown: when the piston 26 moves upward to the top dead center, the fuel in the combustion chamber 27 is compressed to an ignitable state, and the spark plug ignites the fuel in the combustion chamber 27. The fuel combustion and expansion push the piston 26 downward to perform work. At this time, the intake valve 25 is closed, and a portion of the exhaust gas 33 after the fuel combustion is discharged through the exhaust duct 18. The opening 21 designed in the piston skirt is offset and closed from the exhaust duct 18 connected to the exhaust muffler 23. The descending piston 26 compresses the mixed gas 32 in the crankcase 22; the exhaust is as shown in FIG. Figure 3 When the piston 26 descends to near bottom dead center, the scavenging passage 19 communicates with the combustion chamber 27 and the exhaust passage 18. The compressed mixture 32 in the crankcase 22 flows into the combustion chamber 27 through the connected scavenging passage 19, sweeping the remaining exhaust gas 33 in the combustion chamber to the outside through the exhaust passage 18, completing the scavenging process. The scavenged and discharged exhaust gas 33 enters the exhaust muffler 23 (the exhaust gas 33 will be re-inhaled into the crankcase of the adjacent cylinder when the adjacent cylinder is compressing and inhaling). The exhaust gas circulating in the mixture participates in the combustion process, e.g. Figure 4As shown: the piston 26 moves upward from the bottom dead center, and the mixture 32 remaining in the combustion chamber 27 is continuously compressed by the piston 26. The space in the combustion chamber 27 is also compressed, and a negative pressure is formed in the crankcase 22. At this time, the scavenging passage 19 is closed again, and the intake valve 25 is opened again, sucking in new fresh air and fuel 34 from the intake port. When the piston moves up to near the top dead center, the custom-designed opening 21 on the piston skirt 20 is connected to the exhaust muffler 23 again through the exhaust passage 18, and at the same time, the new exhaust gas 35 discharged from the adjacent cylinder into the exhaust muffler 23 is sucked in again. A new mixture 36 mainly composed of new fresh air and fuel 34 and new exhaust gas 35 is formed inside the crankcase. Figure 5 As shown: when the piston 26 moves upward to the top dead center, the original mixture 32 is compressed to the ignition state, and the spark plug ignites the original mixture 32. The original mixture 32 burns and expands, pushing the piston 26 downward again to perform work. At this time, the intake valve 25 is closed again, and a portion of the exhaust gas 37 after the original mixture 32 is burned is discharged through the exhaust passage 18. The opening 21 designed in the piston skirt 20 and the exhaust passage 18 connected to the exhaust muffler 23 are again offset and closed. The descending piston 26 compresses the new mixture 36 in the crankcase 22 again; Figure 6 When the piston 26 descends near bottom dead center, the scavenging passage 19 reopens, connecting it to the combustion chamber 27 and the exhaust passage 18. The compressed new mixture 36 in the crankcase 22 flows into the combustion chamber 27 through the connected scavenging passage 19, sweeping the remaining exhaust gas 37 from the combustion of the original mixture 32 in the combustion chamber 27 to the outside through the exhaust passage 18, completing the scavenging process. The swept and discharged exhaust gas 37 enters the exhaust muffler 23 (the exhaust gas 37 is re-inhaled into the crankcase of the adjacent cylinder during compression intake). Thus, the exhaust gas recirculation system of the two-stroke engine of the present invention completes a complete cycle. The recycled exhaust gas from the mixture participates in the entire combustion process, thereby increasing specific heat capacity, lowering combustion temperature, improving thermal efficiency, reducing fuel consumption, and improving fuel combustion stability.

[0029] Example 2

[0030] In-line twin-cylinder two-stroke engine exhaust gas recirculation system device A, B twin-cylinder exhaust and intake working process: like Figure 7 As shown, when piston A26 in cylinder A ascends to inhale, cylinder B is exchanging air. Exhaust gas B30 discharged and swept out by cylinder B enters exhaust muffler G through exhaust duct B18. The negative pressure inside crankcase A22 of cylinder A at this time causes exhaust gas B30 discharged from cylinder B into exhaust muffler G to be drawn into crankcase A22 through exhaust duct A18 and opening A21 designed on piston skirt A20. It then combines with the inhaled fresh air and fuel A31 to form a mixture A32. like Figure 8As shown, when piston B26 in cylinder B ascends to inhale, cylinder A is exchanging air. Exhaust gas A30 discharged and swept out of cylinder A enters exhaust muffler G through exhaust duct A18. The negative pressure inside crankcase B22 of cylinder B then draws exhaust gas A30, which was discharged from cylinder A into exhaust muffler G, through exhaust duct B18 and opening B21 designed on piston skirt B20 into crankcase B22. There, the exhaust gas combines with the inhaled fresh air and fuel B31 to form a mixture B32. The detailed circulation working process of each cylinder of the exhaust gas recirculation system of the in-line two-cylinder two-stroke engine is the same as that of Example 1 and will not be repeated here. The exhaust gases A30 and B30 recycled from the mixture A32 and B32 participate in the entire combustion process, achieving the purpose of increasing specific heat capacity, reducing combustion temperature, improving thermal efficiency, reducing fuel consumption and improving fuel combustion stability.

[0031] Example 3

[0032] Working process of exhaust gas recirculation system of horizontally opposed four-cylinder two-stroke engine: A typical horizontally opposed four-cylinder two-stroke engine has four cylinders, two opposite each other, on either side of the engine. To achieve optimal balance, the cylinders are typically staggered 180 degrees. That is, while one cylinder on one side is performing a stroke, the opposite cylinder on the other side is performing the opposite stroke. The cylinders are numbered 1, 2, 3, and 4, with cylinders 1 and 4 on one side and cylinders 2 and 3 on the other. A common staggered order is 1-3-2-4.

[0033] like Figure 9 As shown, when cylinder 1 is in the intake stroke, cylinder 3 is in the exhaust stroke. The exhaust gas 330 discharged and swept out by cylinder 3 enters the exhaust muffler 13 and is sucked into the crankcase 122 through the designed opening 120 of the piston group 121 of cylinder 1, forming a mixture of fresh air, fuel 131, and exhaust gas 330. Cylinders 2 and 4 are in the power and compression strokes, respectively, preparing for the exhaust gas 230 discharged and swept out by cylinder 2 to enter the exhaust muffler 24 and then be sucked into the crankcase 422 through the designed opening 420 of the piston group 421 of cylinder 4 to form a mixture of fresh air, fuel 431, and exhaust gas 230. like Figure 10As shown, when cylinder 1 is in the compression stroke, cylinder 3 is in the power stroke, and the exhaust gas 330 discharged and swept out by cylinder 3 is then drawn into the crankcase 122 through the designed opening 120 of the piston group 121 of cylinder 1 to form a mixture of fresh air, fuel 131, and exhaust gas 330; while cylinders 2 and 4 are in the exhaust and intake strokes, respectively, and the exhaust gas 230 discharged and swept out by cylinder 2 enters the exhaust muffler 24 and is drawn into the crankcase through the designed opening 420 of the piston group 421 of cylinder 4 to form a mixture of fresh air, fuel 431, and exhaust gas 230; The detailed operating steps of the exhaust gas recirculation system for a horizontally opposed four-cylinder two-stroke engine are identical to those in Example 1 and are not repeated here. The exhaust gas recirculated from the mixture participates in the combustion cycle of cylinders 1, 2, 3, and 4 in a timed sequence, thereby increasing specific heat capacity, lowering combustion temperature, improving thermal efficiency, reducing fuel consumption, and enhancing combustion stability.

[0034] The exhaust gas recirculation system device of the present invention has a high degree of flexibility and wide applicability, and can adapt to various multi-cylinder two-stroke engine layouts, such as V-type engines or W-type engines. Regardless of the layout, as long as the reasonable coordination of the operating timing phase difference between adjacent cylinders is ensured, the exhaust gas can be effectively recycled and utilized, and should be included in the protection scope of the present invention.

Claims

1. A two-stroke engine exhaust gas recirculation system device, characterized in that: The invention comprises: a piston skirt (20) provided with an opening (21) for forming an air flow channel between the interior of a crankcase (22) and an exhaust muffler (23) under a specific operating state of the engine, so that during the intake process of the engine cylinder, the exhaust gas (30) discharged from the adjacent cylinder into the exhaust muffler (23) can be guided into the crankcase (22); an air flow introduction mechanism during the intake phase of the engine, wherein the mechanism compresses the combustion chamber (27) space by the piston (26) upward, thereby forming a negative pressure inside the crankcase (22), closing the scavenging duct (19), and opening the intake valve (25), so that fresh air and fuel (31) and the exhaust gas (30) are introduced into the crankcase (22) to form a mixed gas.

2. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The piston group (20) is provided with a customized opening design (21).

3. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The air flow channel between the crankcase (22) and the exhaust muffler (23) is communicated through an exhaust duct (18).

4. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The specific operating state of the engine is that the piston (26) moves upward to the vicinity of the top dead center, and the crankcase (22) is connected to the opening design (21), the exhaust duct (18), and the exhaust muffler (23).

5. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: Negative pressure is formed inside the crankcase (22) to draw the exhaust gas (30) in the exhaust muffler (23) into the crankcase (22).

6. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The exhaust gas (30) is mainly composed of high specific heat capacity gases such as CO2 and H2O, and its temperature is higher than the ambient temperature.

7. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The exhaust gas (30) is preheated in the crankcase (22) to form a mixture with fresh air and fuel (31).

8. The exhaust gas recirculation system of a two-stroke engine according to claim 1, characterized in that: The two-stroke engines suitable for the engine exhaust gas recirculation system device include: in-line two-cylinder and horizontally opposed four-cylinder engines.

9. A two-stroke engine, characterized in that: include: Engine body; The exhaust gas recirculation system device for a two-stroke engine as claimed in claim 1, wherein the system device is used on the engine body, wherein the piston skirt (20) is provided with an opening (21) and is a component of the piston (26) of the engine body, and the exhaust muffler (23) is connected to the exhaust system of the engine body and works in coordination with the intake system of the engine body.

10. A multi-cylinder two-stroke engine, characterized in that: include: A multi-cylinder engine body; a two-stroke engine as claimed in claim 9, wherein the engine exhaust gas recirculation device realizes exhaust gas recirculation through the operating timing between adjacent cylinders of the multi-cylinder engine body.

Images