Two-stroke aero-piston engine air intake system and air intake flow control method

Abstract

The application relates to the field of aeroengines, in particular to a two-stroke aero-piston engine air intake system and an air intake flow control method. The system comprises an air filter, a throttle body, an oil injector, a reed valve and a fuel supply unit for supplying oil to the oil injector which are communicated through a connecting pipeline, and further comprises a cooling control subsystem, the cooling control subsystem comprising a cooling injector which is arranged on the connecting pipeline downstream of the throttle body and upstream of the oil injector; the inner wall surface of the connecting pipeline is provided with a non-uniform protruding structure to improve the proportion of the air intake along the resistance. The scheme can solve the technical problem that the air intake flow of the two-stroke aero-piston engine has large discreteness under low load, and realizes the technical effect of improving the consistency of the air intake flow under the low load of the engine.

Description

Technical Field

[0001] This invention relates to the field of aero-engines, specifically to an intake system and intake flow control method for a two-stroke aero-piston engine. Background Technology

[0002] With the rapid development of the aviation industry, two-stroke aviation piston engines are widely used in light aircraft such as UAVs due to their advantages such as high power-to-weight ratio and simple structure. The intake system of a two-stroke aviation piston engine typically includes components such as an air filter, throttle body, connecting pipes, fuel injectors, and reed valves. The performance of these components directly affects the engine's operational stability and efficiency.

[0003] Currently, the intake system of two-stroke aircraft piston engines generally consists of an air filter, intake manifold, throttle valve, and fuel injector. By adjusting the intake air volume through the throttle opening and matching the fuel supply through the fuel injector, the combustion requirements under different operating conditions can be met. Due to its compact layout and convenient maintenance, this structure has become the mainstream configuration for light aircraft power systems.

[0004] However, the existing two-stroke aircraft piston engine intake system has the following technical problems: 1. Under low load conditions, the intake air temperature increases after throttling by the throttle body, and the airflow viscosity increases, resulting in a significant increase in throttling losses and unstable intake flow. 2. The intake system consists of multiple components such as air filter, throttle body, and reed valve. The cumulative manufacturing and assembly errors of each component make it difficult to predict the overall accuracy. Especially when the throttle body opening is below 50%, the intake flow rate difference can reach 30% to 50%, and the speed difference can exceed 300 rpm. 3. The reed valve is made of carbon fiber composite material, which has a large dispersion in mechanical properties, further aggravating the instability of the intake air volume under low load conditions. 4. Existing technologies that use reeds to screen and match or control the assembly consistency of the throttle body are labor-intensive and have limited effectiveness, failing to fundamentally solve the problem of large dispersion in intake flow under low-load conditions.

[0005] These technical problems seriously affect the performance consistency and operational stability of two-stroke aero piston engines under low-load conditions, and there is an urgent need for a technical solution that can effectively reduce throttling losses and stabilize intake airflow under low load conditions. Summary of the Invention

[0006] To address the technical problem of large dispersion in intake airflow of two-stroke aero piston engines under low load and to improve the consistency of intake airflow under low load conditions, this invention provides an intake system and intake airflow control method for a two-stroke aero piston engine.

[0007] The technical solution adopted by this invention to solve its technical problem is as follows: A two-stroke aero-piston engine intake system is provided, comprising an air filter, throttle body, injector, reed valve, and fuel supply unit for supplying fuel to the injector, connected by a connecting pipe. The system is characterized by further including a cooling control subsystem, which includes a cooling injector located on the connecting pipe between the throttle body and the injector. The cooling injector is used to cool the intake air after throttling by the throttle body to reduce throttling losses. The inner wall of the connecting pipe has a non-uniform protrusion structure to increase the proportion of intake drag along the path.

[0008] Preferably, the cooling control subsystem further includes an air pump, a solenoid valve, and a control unit. The cooling injector adopts a high-pressure air-clamping injection mode. The air pump draws air from downstream of the air filter, pressurizes it, and supplies it to the cooling injector. The high-pressure oil pump draws fuel from the fuel tank, pressurizes it, and supplies it to the cooling injector. The control unit is electrically connected to the air pump, the solenoid valve, the high-pressure oil pump, and the cooling injector, respectively, and is used to control the intake air temperature rise after throttling.

[0009] Preferably, the nozzle of the cooling injector is located in the low-pressure region on the intake contraction side downstream of the throttle body's throttle plate rotation shaft, the spray direction of the cooling injector is set at an obtuse angle to the air outlet direction of the throttle body, and the spray angle of the cooling injector is ≤37°.

[0010] Preferably, the thermal conductivity of the connecting pipe wall is 0.2~0.3 W / m. K, the inner wall roughness Ra of the connecting pipe is ≥12.5, the connecting pipe is made of PA66 material, and its outer wall is coated with a heat insulation coating.

[0011] Preferably, the control unit is also connected to the throttle body signal, and the control unit is configured to: control the cooling injector to stop working when the throttle body opening is greater than 50%; and control the cooling injector to start and adjust the injection parameters when the throttle body opening is ≤50%, so that the intake air temperature fluctuation downstream of the throttle body is maintained within ±2℃ of the intake air reference temperature.

[0012] Secondly, the present invention also provides a method for controlling the intake flow of a two-stroke aircraft piston engine, based on the above-mentioned two-stroke aircraft piston engine intake system, comprising the following steps: S1. Under low engine load conditions, the intake air after throttling is cooled by a cooling injector located downstream of the throttle body, which reduces the viscosity of the airflow and thus reduces throttling losses. S2. By using connecting pipes with non-uniform protrusions on the inner wall, the proportion of intake friction is increased, and the weight of the impact of throttling loss on intake flow is reduced. S3. Fuel injection is completed before the cylinder by an injector located downstream of the cooling injector, so as to achieve stable control of the intake air volume under low engine load conditions.

[0013] Preferably, in step S1, the cooling injector adopts a high-pressure air-jet injection mode, and the injection medium is a mixture of pressurized gasoline and pressurized air, wherein the pressurized air is obtained by pressurizing with an air pump, and the pressurized gasoline is obtained by pressurizing with a high-pressure oil pump from the fuel tank.

[0014] Furthermore, in step S1, the pressure of the boosted air is controlled to be at least 7 bar, the pressure of the boosted gasoline is controlled to be at least 8 bar, and the injection parameters of the cooling injector are adjusted so that the intake air temperature fluctuation downstream of the throttle body is maintained within ±2°C of the intake air reference temperature.

[0015] Furthermore, in step S2, the connecting pipe uses a thermal conductivity of 0.2~0.3 W / m. K is made of PA66 material with an inner wall roughness of Ra≥12.5 and an outer wall coated with an insulating coating to enhance the heat insulation effect.

[0016] Furthermore, it also includes a working condition switching step: real-time acquisition of the throttle body opening; when the throttle body opening is greater than 50%, the cooling injector is turned off, and fuel injection is completed only through the fuel injector; when the throttle body opening is ≤50%, the cooling injector is activated to perform the injection cooling operation in step S1.

[0017] The beneficial effects of this invention are as follows: 1. The cooling control subsystem cools the intake air after throttling by the throttle body, reducing airflow viscosity and throttling loss. At the same time, the low thermal conductivity material and high roughness inner wall design of the connecting pipes increase the proportion of friction resistance, thereby reducing the proportion of throttling loss under medium and low intake load conditions and effectively controlling the consistency of engine intake performance under low load. 2. The technical solution of the present invention significantly reduces the precision requirements of the throttle body and reed valve components by adjusting the ratio of throttle loss to friction resistance, effectively avoids the intake flow difference caused by the accumulation of component processing errors and assembly errors, greatly reduces the assembly difficulty and component processing and production costs, and shortens the production cycle. 3. The cooling injector adopts a high-pressure air-jet method, which absorbs heat through oil atomization and evaporation, causing the gas viscosity to decrease as the temperature decreases. At the same time, the specific spray angle setting controls the formation of vortices, reduces the dissipation effect inside the flow field, and further improves the stability of the system. 4. This invention uses an adaptive control strategy to intelligently switch working modes under different load conditions, which ensures the stability of intake flow under low load conditions without affecting engine performance under high load conditions, thereby improving the reliability of the engine system and greatly controlling the manufacturing cost of individual components and the system selection cost.

[0018] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 The system architecture diagram of the intake system for a two-stroke aero-piston engine provided by the present invention; Figure 2 A structural diagram of the throttle body of the intake system of a two-stroke aero-piston engine provided by the present invention; Figure 3 The flowchart shows the intake flow control method for a two-stroke aero-piston engine provided by the present invention.

[0020] Figure label: 100-Air filter; 200-Throttle body; 201-Throttle plate; 300-Injector; 400-Reed valve; 500-Cooling injector; 501-Nozzle; 600-Air pump; 700-Solenoid valve; 800-High-pressure fuel pump; 900-Fuel tank; 1000-Fuel pump; 10-Fuel supply unit; 20-Cooling control subsystem. Detailed Implementation

[0021] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0022] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0023] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0024] To address the technical problem of large dispersion in intake airflow of two-stroke aero piston engines under low load and to improve the consistency of intake airflow under low load conditions, this invention provides an intake system and intake airflow control method for a two-stroke aero piston engine.

[0025] Specifically, in combination Figures 1-3 The intake system of a two-stroke aero-piston engine is connected by a connecting pipe to an air filter 100, a throttle body 200, an injector 300, a reed valve 400, and a fuel supply unit 10 that supplies fuel to the injector 300. These components are sequentially connected to form a complete intake and fuel supply path. The air filter 100 is used to filter out dust and impurities in the intake air, preventing impurities from causing the throttle body 200 to stick, the injector 300 to become clogged, and the reed valve 400 to wear, thus ensuring the long-term stable operation of the intake system. The throttle body 200 is used to adjust the intake flow area according to the engine load requirements, realizing basic control of the intake flow. The connecting pipe provides a closed channel for the intake flow. The injector 300 is used to inject fuel into the intake air to form a combustible mixture. The reed valve 400 is used to realize one-way intake air flow and match the scavenging timing of the two-stroke engine. The fuel supply unit 10, in conjunction with the fuel pump 1000, provides fuel with stable pressure to the injector 300, ensuring the accuracy of fuel injection metering.

[0026] The intake system also includes a dedicated cooling control subsystem 20. The core component of the cooling control subsystem 20 is a cooling injector 500. The cooling injector 500 is oriented on the connecting pipe between the throttle body 200 and the fuel injector 300, and is positioned directly in front of the airflow area after throttling by the throttle body 200. It can directly atomize and cool the high-temperature intake air generated by the small opening of the throttle body 200. By absorbing heat through the evaporation of the working fluid, the intake air temperature is quickly reduced, thereby reducing the viscosity of the airflow and reducing throttling losses. This fundamentally alleviates the problem of intake flow fluctuation caused by throttling temperature rise under low load.

[0027] The connecting pipes are made of low thermal conductivity material, which can effectively block the transfer of heat from the engine compartment to the inside of the pipes and avoid the intake air temperature from being affected by the external environment. At the same time, the inner wall of the connecting pipes is machined with a high roughness structure or a non-uniform protrusion structure, which can significantly increase the proportion of the intake air friction resistance in the pipes, dilute the impact of throttling loss on the total intake air flow, and thus weaken the interference of the cumulative manufacturing tolerances and assembly errors of components such as the throttle body 200 and the reed valve 400 on the stability of the intake air flow under low load, ensuring the consistency of the intake air flow.

[0028] Furthermore, the cooling control subsystem 20 also includes an air pump 600, a solenoid valve 700, and a control unit. The cooling injector 500 adopts a high-pressure air-fuel injection mode. Air is drawn from downstream of the air filter 100 by the air pump 600, pressurized, and supplied to the cooling injector 500. Fuel is drawn from the fuel tank 900 by the high-pressure oil pump 800, pressurized, and supplied to the cooling injector 500. The control unit is electrically connected to the air pump 600, the solenoid valve 700, the high-pressure oil pump 800, and the cooling injector 500, respectively, and is used to control the intake air temperature rise after throttling. The cooling injector 500 adopts a high-pressure air-fuel injection structure, achieving efficient atomization cooling through independent supply of air and oil.

[0029] Specifically, the booster air circuit includes an air pump 600 and a solenoid valve 700. The air pump 600 draws filtered clean air from downstream of the air filter 100 and pressurizes it stably to 7 bar. After the gas flow is precisely controlled by the solenoid valve 700, it is delivered to the gas interface of the cooling injector 500, ensuring stable gas supply pressure and controllable flow. The booster oil circuit includes a high-pressure oil pump 800. The high-pressure oil pump 800 draws gasoline from the fuel supply unit 10 and pressurizes it stably to 8 bar, which is directly delivered to the fuel interface of the cooling injector 500. The combination of high-pressure oil and gas can achieve ultra-fine atomization, greatly improve the evaporation heat absorption efficiency, and enhance the cooling effect.

[0030] Furthermore, the nozzle 501 of the cooling injector 500 is precisely positioned in the low-pressure region on the intake contraction side downstream of the throttle plate 201 rotation shaft of the throttle body 200, specifically 25mm from the rotation shaft. This position is in the area with minimal airflow disturbance and the most stable negative pressure at small throttle openings, ensuring that atomized fuel quickly integrates into the mainstream airflow and preventing oil droplets from adhering to the pipe wall and forming an oil film. The spray direction of the cooling injector 500 is set at a 153° obtuse angle to the exhaust direction of the throttle body 200, which can effectively suppress... The vortex generated after the throttle body 200 reduces internal airflow dissipation losses. At the same time, the spray angle of the cooling injector 500 is limited to 37°, which can completely cover the intake flow section and ensure uniform cooling of the airflow throughout the entire area after throttling. This coordinated design of position, angle and spray pattern can minimize airflow dissipation under small opening conditions after the throttle body 200, and ensure that the fuel injection and airflow are fully mixed and heat exchanged. Under the core low load condition of 50% throttle opening of the engine, the optimal throttling cooling and flow stability effect is achieved.

[0031] Furthermore, the thermal conductivity of the connecting pipe wall is precisely controlled to 0.2 W / m. K possesses excellent thermal insulation performance, with a stable inner wall roughness Ra of 12.5 in the connecting pipe, resulting in a significant improvement in friction resistance. The connecting pipe is integrally injection molded from PA66 material, which combines structural rigidity with low thermal conductivity, meeting the assembly strength and lightweight requirements of aero-engines. Furthermore, its outer wall is uniformly coated with an insulation coating.

[0032] In a preferred embodiment, the insulating coating is made of gray paint, which improves the weather resistance of the pipeline while further reducing the heat dissipation area of ​​the pipe wall and enhancing the insulation effect, thus maximizing the stability of the intake air temperature inside the pipeline. The low thermal conductivity of the connecting pipeline and the high roughness of the inner wall surface work together to ensure that the intake system remains in a stable insulating state throughout, avoiding intake air temperature fluctuations, and effectively increasing the intake resistance share. This significantly reduces the impact of component precision errors on low-load intake airflow, resulting in a more stable intake airflow with less dispersion.

[0033] Furthermore, the control unit is also connected to the throttle body 200 signal to collect the throttle body 200 opening signal in real time to execute the operating condition adaptive control logic. The control unit is configured with a dedicated operating condition switching and temperature control mode: when the throttle body 200 opening is greater than 50%, the engine is in a medium-high load condition, and the control unit immediately controls the cooling injector 500 to stop working to avoid the cooling intervention affecting the high load intake charge and ensure the engine power output performance; when the throttle body 200 opening is ≤50%, the engine is in a low load condition, and the control unit quickly starts the cooling injector 500 and adjusts the injection pressure, injection quantity and other parameters in a closed loop to keep the intake air temperature fluctuation downstream of the throttle body 200 within ±2℃ of the intake air reference temperature.

[0034] Specifically, the control unit precisely controls the injection volume and oil-air ratio of the cooling injector 500 by adjusting the opening and closing duty cycle of the solenoid valve 700 and the output power of the high-pressure oil pump 800 in real time, ensuring that the intake air temperature downstream of the throttle body 200 remains constant under low load conditions, thus ensuring the stability and consistency of the intake air volume from the control level.

[0035] It should be noted that the working principle of the intake system of this two-stroke aero-piston engine is as follows: Under low to medium intake load conditions, the intake air volume is stably controlled by reducing the proportion of throttling losses and increasing the proportion of frictional resistance. The system achieves multi-point staged injection by adding a cooling injector 500 after the intake throttle body 200 and retaining the main injector 300 near the reed valve 400. Gasoline itself has a low boiling point and high volatility. After being atomized by high-pressure air-clamping, it can quickly absorb the heat of the intake air, significantly reducing the intake air temperature. This causes the gas viscosity to decrease significantly with the decrease in temperature, and the airflow resistance decreases simultaneously. At the same time, with a specific spray angle and installation position, the formation of vortices is effectively suppressed, and the dissipation effect inside the flow field is weakened. The insulation capacity of non-throttling links is improved by using low thermal conductivity pipes and an outer wall insulation coating. Combined with a high-roughness structure on the inner wall to increase frictional resistance, the intake resistance distribution ratio is further optimized.

[0036] This design works synergistically from multiple dimensions, including flow field regulation, temperature control, and resistance distribution, to significantly improve the consistency of engine intake performance under low load. It also greatly reduces the system's requirements for the machining and assembly precision of the throttle body 200 and reed valve 400 components, eliminating cumbersome processes such as reed valve 400 screening and matching and throttle body 200 assembly consistency calibration. This effectively reduces component manufacturing costs, assembly screening costs, and production time, while improving the overall engine performance stability and reliability.

[0037] Furthermore, the present invention also provides a method for controlling the intake flow of a two-stroke aircraft piston engine, based on the above-mentioned two-stroke aircraft piston engine intake system, comprising the following steps: S1. Under low engine load conditions, the intake air after throttling is cooled by the cooling injector 500 located downstream of the throttle body 200, thereby reducing the viscosity of the airflow and minimizing throttling losses.

[0038] The cooling injector 500, located downstream of the throttle body 200, targets and cools the intake air that has heated up after throttling. The ultra-fine gasoline droplets formed by high-pressure air-clamping injection rapidly evaporate and absorb heat, accurately reducing the intake air temperature to reduce airflow viscosity. This fundamentally reduces the throttling loss caused by the small opening of the throttle body 200. Furthermore, the injection parameters are adjusted in a closed loop by the control unit to keep the intake air temperature downstream of the throttle body 200 stable within the range of ±2℃ of the reference temperature.

[0039] S2. By using connecting pipes with low thermal conductivity and high inner wall roughness, the proportion of intake friction is increased, the weight of throttling loss on intake flow is reduced, and the interference of component precision errors on low-load intake flow is weakened.

[0040] It utilizes PA66 material with low thermal conductivity (0.2~0.3W / m). K) Connecting pipes with an inner wall roughness Ra≥12.5 and an outer wall coated with an insulating coating steadily increase the proportion of friction resistance during the full airflow process, reconstruct the resistance distribution relationship of the intake system, significantly reduce the weight of throttling loss on intake flow, and weaken the interference of manufacturing tolerances, assembly errors and mechanical performance dispersion of reed valve 400 on low-load intake flow from a structural perspective.

[0041] S3. Fuel injection is performed before the cylinder by the injector 300 located downstream of the cooling injector 500, thereby achieving stable control of the intake air volume under low engine load conditions.

[0042] Precise fuel injection is achieved by the injector 300 located downstream of the cooling injector 500. The control unit incorporates the amount of fuel injected by the cooling injector 500 into the total fuel injection calculation and dynamically compensates for it to ensure a stable air-fuel ratio. This allows the cooled and stabilized intake air to mix fully with the fuel, ultimately achieving precise and stable control of the intake air volume under low engine load conditions.

[0043] In this embodiment, the cooling injector 500 adopts a high-pressure air-fuel mixture injection mode, and the injection medium is a mixture of pressurized gasoline and pressurized air. The pressurized air is obtained by pressurizing the engine intake air through the air pump 600, and the pressurized gasoline is obtained by pressurizing the engine fuel tank 900 through the fuel pump. This air-fuel mixture injection method can improve the atomization effect and effectively reduce the increase in airflow viscosity caused by the temperature rise of the throttle body 200.

[0044] Furthermore, in step S1, the pressure of the boosted air is controlled to be at least 7 bar, and the pressure of the boosted gasoline is controlled to be at least 8 bar. Simultaneously, the injection parameters of the cooling injector 500 are adjusted to maintain the intake air temperature fluctuation downstream of the throttle body 200 within ±2°C of the intake air reference temperature. By adjusting the operating parameters of the solenoid valve 700 and the high-pressure fuel pump 800 in real time through the control unit, precise control of the injection quantity and injection ratio is ensured, thereby achieving stable intake air temperature.

[0045] Furthermore, in step S2, the connecting pipes use materials with a thermal conductivity of 0.2~0.3 W / m. Made of PA66 material, the K-type pipe has an inner wall roughness Ra≥12.5 and an outer wall coated with an insulating coating to enhance heat insulation. This design further improves the heat insulation capacity of the outer wall of the connecting pipe by reducing the heat dissipation surface and increasing the heat insulation effect. At the same time, it increases the proportion of intake system friction resistance, thereby weakening the impact of component precision errors of the throttle body 200 and reed valve 400 on low-load intake flow.

[0046] Furthermore, this embodiment also includes a working condition switching step: The actual opening degree of the throttle body 200 is acquired in real time. When the throttle body 200 opening degree is greater than 50%, the cooling injector 500 is shut off, and fuel injection is completed only through the fuel injector 300; when the throttle body 200 opening degree is ≤50%, the cooling injector 500 is activated to perform the injection cooling operation in step S1. This working condition switching strategy ensures the efficient operation of the system under different load conditions.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An intake system for a two-stroke aircraft piston engine, comprising an air filter (100), a throttle body (200), an injector (300), and a reed valve (400) connected by connecting pipes, and a fuel supply unit (10) for supplying fuel to the injector (300), characterized in that, It also includes a cooling control subsystem (20), which includes a cooling injector (500). The cooling injector (500) is located on the connecting pipe between the throttle body (200) and the fuel injector (300) and is used to cool the intake air after throttling by the throttle body (200) to reduce throttling losses. The inner wall of the connecting pipe is provided with a non-uniform protrusion structure to increase the proportion of intake air friction resistance.

2. The intake system for a two-stroke aero-piston engine according to claim 1, characterized in that, The cooling control subsystem (20) also includes an air pump (600), a solenoid valve (700), and a control unit. The cooling injector (500) adopts a high-pressure air-clamping injection mode. The air pump (600) draws air from downstream of the air filter (100), pressurizes it, and supplies it to the cooling injector (500). The high-pressure oil pump (800) draws fuel from the fuel tank (900), pressurizes it, and supplies it to the cooling injector (500). The control unit is electrically connected to the air pump (600), the solenoid valve (700), the high-pressure oil pump (800), and the cooling injector (500) respectively, and is used to control the intake air temperature rise after throttling.

3. The intake system for a two-stroke aero-piston engine according to claim 2, characterized in that, The nozzle (501) of the cooling injector (500) is located in the low-pressure region on the intake contraction side downstream of the rotation axis of the throttle plate (201) of the throttle body (200). The spray direction of the cooling injector (500) is set at an obtuse angle to the outlet direction of the throttle body (200), and the spray angle of the cooling injector (500) is ≤37°.

4. The intake system for a two-stroke aero-piston engine according to claim 1, characterized in that, The thermal conductivity of the connecting pipe wall is 0.2~0.3 W / m. K, the inner wall roughness Ra of the connecting pipe is ≥12.5, the connecting pipe is made of PA66 material, and its outer wall is coated with a heat insulation coating.

5. The intake system for a two-stroke aircraft piston engine according to any one of claims 1 to 4, characterized in that, The control unit is also signal-connected to the throttle body (200), and the control unit is configured to: control the cooling injector (500) to stop working when the opening of the throttle body (200) is greater than 50%; and control the cooling injector (500) to start and adjust the injection parameters when the opening of the throttle body (200) is ≤50%, so that the intake air temperature fluctuation downstream of the throttle body (200) is maintained within ±2℃ of the intake air reference temperature.

6. A method for controlling the intake airflow of a two-stroke aero-piston engine, characterized in that, The two-stroke aircraft piston engine intake system based on any one of claims 1 to 5 is implemented by the following steps: S1. Under low engine load conditions, the intake air after throttling is cooled by a cooling injector (500) located downstream of the throttle body (200), thereby reducing the viscosity of the airflow and minimizing throttling losses. S2. By using connecting pipes with non-uniform protrusions on the inner wall, the proportion of intake friction is increased, and the weight of the impact of throttling loss on intake flow is reduced. S3. Fuel injection is performed before the cylinder by the injector (300) located downstream of the cooling injector (500), thereby achieving stable control of the intake air volume under low engine load conditions.

7. The intake airflow control method for a two-stroke aero-piston engine according to claim 6, characterized in that, In step S1, the cooling injector (500) adopts a high-pressure air-jet injection mode, and the injection medium is a mixture of pressurized gasoline and pressurized air. The pressurized air is obtained by pressurizing the air pump (600), and the pressurized gasoline is obtained by pressurizing the fuel tank (900) through the high-pressure oil pump (800).

8. The intake airflow control method for a two-stroke aero-piston engine according to claim 7, characterized in that, In step S1, the pressure of the boosted air is controlled to be at least 7 bar, the pressure of the boosted gasoline is controlled to be at least 8 bar, and the injection parameters of the cooling injector (500) are adjusted so that the intake air temperature fluctuation downstream of the throttle body (200) is maintained within ±2°C of the intake reference temperature.

9. The intake airflow control method for a two-stroke aero-piston engine according to claim 6, characterized in that, In step S2, the connecting pipe has a thermal conductivity of 0.2~0.3 W / m. K is made of PA66 material with an inner wall roughness of Ra≥12.5 and an outer wall coated with an insulating coating to enhance the heat insulation effect.

10. The intake airflow control method for a two-stroke aero-piston engine according to claim 6, characterized in that, It also includes a working condition switching step: real-time acquisition of the opening degree of the throttle body (200); when the opening degree of the throttle body (200) is greater than 50%, the cooling injector (500) is turned off, and fuel injection is completed only through the fuel injector (300); when the opening degree of the throttle body (200) is ≤50%, the cooling injector (500) is started to perform the injection cooling operation of step S1.

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