Dual-channel series cooling structure of aviation piston engine for unmanned aerial vehicle

Abstract

The invention discloses a dual-channel series cooling structure of an aviation piston engine for an unmanned aerial vehicle, belongs to the field of aviation piston engines, and relates to a cylinder body cooling structure of a four-cylinder two-stroke piston engine. According to the four-cylinder two-stroke piston engine, the two wind scoopers which are provided with the interlayer air ducts and are in bilateral symmetry are designed and symmetrically installed outside a cylinder body of the four-cylinder two-stroke piston engine, each wind scooper forms the inner side main air duct and the interlayer air duct, and cold air entering from the inner side main air ducts cools a first cylinder close to a cold air inlet; after cold air entering from the interlayer air duct is mixed with cold air flowing through the first cylinder, the secondary cylinder body far away from the cold air inlet is cooled. The effect that a rear-end secondary cylinder is close to an independent cooling system is achieved in a limited space, the inter-cylinder balanced cooling effect of direct efficient cooling of a first cylinder and optimized mixed cooling of the secondary cylinder is achieved through the synergistic effect of a main air duct and interlayer air supplement, the problem that the cooling effect is not uniform due to a traditional cooling design is solved, and the overall cooling efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of aviation piston engines, and in particular to a dual-channel series cooling structure of an aviation piston engine for a drone, which is a cylinder cooling structure of a four-cylinder two-stroke piston engine. Background Art

[0002] Traditional air-cooled engines usually use single-layer air shroud cooling technology. Cold air enters from one side of the engine, first flows through the right cylinder block and then flows through the left cylinder block. This design is simple, but it cannot effectively distribute the cold air, resulting in low cooling efficiency.

[0003] The cylinder block of a four-cylinder two-stroke piston engine is cooled by a single-layer air shroud. Cold air generally enters the air shroud from both sides of the engine, first cooling the first cylinder block and the third cylinder block near the cold air inlet on both sides, and then the cold air on both sides flows to the second cylinder block located at the rear side of the first cylinder block and the fourth cylinder block located at the rear side of the third cylinder block to cool them. The cold air takes away a lot of heat through the first cylinder block at the front end, so the first cylinder block and the third cylinder block near the cold air inlet have good cooling effects. When the cold air carries the heat of the first cylinder block at the front end and then cools the second cylinder block at the rear end, the cooling effect is significantly reduced due to the increase in wind temperature, resulting in a difference in cooling effects between the front and rear cylinder blocks on both sides, that is, the cooling effects of the first and third cylinder blocks are better, while the cooling effects of the second and fourth cylinder blocks are significantly reduced. The temperature difference between the front and rear cylinder blocks on both sides will affect the combustion efficiency of the engine, increase the risk of knocking, and cause the engine power and fuel economy to deteriorate.

[0004] Some improvement measures have been tried in the prior art, such as optimizing the shape of the single-layer air shroud, increasing the fan speed, and installing an air shroud inlet and exhaust duct. However, these methods can only partially improve the cooling effect, and installing an air shroud inlet and exhaust duct will also cause an additional problem of a large windward surface. Therefore, the prior art cannot fundamentally solve the problem of uneven cooling of the cylinder block of a four-cylinder two-stroke piston engine.

[0005] Therefore, it is necessary to provide a dual-channel series cooling structure for an aviation piston engine for a UAV to solve the above problems. Summary of the invention

[0006] Technical issues to be solved: To avoid the deficiencies of the prior art, the present invention provides a dual-channel series cooling structure for an aviation piston engine used in an unmanned aerial vehicle. By designing two air guiding covers with sandwich air ducts and being symmetrical left and right, which are symmetrically installed outside the cylinder block of a four-cylinder two-stroke piston engine, each air guiding cover forms two air ducts, namely an inner main air duct and a sandwich air duct. The cold air entering from the inner main air duct cools the first cylinder body near the cold air inlet, and the cold air entering from the sandwich air duct mixes with the cold air flowing through the first cylinder body and then cools the second cylinder body far from the cold air inlet, solving the problems of uneven cooling of the cylinder block of the existing four-cylinder two-stroke piston engine and low cooling efficiency.

[0007] The technical solution of the present invention is: It includes two air guiding covers arranged mirror-symmetrically with respect to a four-cylinder two-stroke piston engine. One air guiding cover is installed outside the two cylinder bodies on the left side of the four-cylinder two-stroke piston engine, and the other air guiding cover is installed outside the two cylinder bodies on the right side of the four-cylinder two-stroke piston engine; A clamping plate is fixed at the inner layer of the air guiding cover near the air inlet end of the air guiding cover. The clamping plate is parallel to the air guiding cover, and a sandwich air duct running through along the air guiding direction is formed between the two. The air inlet of the sandwich air duct is flush with the air inlet of the air guiding cover, and the air outlet of the sandwich air duct is located in the middle inside the air guiding cover and also between the two cylinder bodies on the side where the air guiding cover is installed; a main air duct is formed between the clamping plate and the cylinder block; Among them, the cold air entering the main air duct from the air inlet of the air guiding cover cools the front and rear two cylinder bodies on the side where the air guiding cover is installed in sequence. The cold air entering the sandwich air duct from the air inlet of the sandwich air duct converges into the main air duct from the air outlet of the sandwich air duct and mixes with the cold air flowing through the front-end cylinder body to cool the rear-end cylinder body.

[0008] A further technical solution of the present invention is: The air guiding cover is a shell structure with a U-shaped cross-section. The U-shaped openings of the two air guiding covers face each other, so that their U-shaped shells wrap the corresponding cylinder blocks, and are fixedly connected to the corresponding cylinder blocks through fasteners at their respective U-shaped openings.

[0009] A further technical solution of the present invention is: A notch for avoiding the cylinder exhaust port is provided on one side of the U-shaped opening of each of the two air guiding covers; a notch for avoiding the cylinder exhaust port is also provided at the corresponding position on the corresponding clamping plate.

[0010] A further technical solution of the present invention is: The air guiding cover includes an integral main body part and a convex part. The main body part and the convex part are transitioned by an arc surface; the overall contour of the air guiding cover is convex at the installation clamping plate, forming a convex part far from the front-end cylinder body, so that the clamping plate inside the air guiding cover and the main body part of the air guiding cover are in the same profile plane, and the distance between the clamping plate and the front-end cylinder body is the same as the distance between the main body part and the rear-end cylinder body; an equal-gap sandwich air duct is formed between the clamping plate and the convex part of the air guiding cover, and the air outlet of the sandwich air duct is located at the arc surface transition between the main body part and the convex part of the air guiding cover.

[0011] A further technical solution of the present invention is that: a plurality of reinforcing ribs are provided between the clamping plate and the convex part along the air guiding flow direction, and the reinforcing ribs between the clamping plate and the convex part are used to support and connect the clamping plate and the convex part of the air guiding cover.

[0012] A further technical solution of the present invention is that: a plurality of spark plug mounting holes are provided on the air guiding cover for avoiding the spark plugs mounted on the cylinder block, and corresponding mounting holes for avoiding the spark plugs are also provided at corresponding positions on the corresponding clamping plate.

[0013] A further technical solution of the present invention is that: the two air guiding covers are made of the same material.

[0014] The beneficial effects of the present invention are as follows: The dual-channel series cooling structure of the aviation piston engine for unmanned aerial vehicles according to the present invention improves the traditional single-layer air guiding cover structure, designs an interlayer air duct at the air inlet end, so as to shunt the fresh cold air entering the air guiding cover, enabling the cold air to flow to the main air duct and the interlayer air duct simultaneously. The cold air entering the main air duct cools the front-end cylinder block, and the cold air entering the interlayer air duct converges into the main air duct at the air outlet of the interlayer air duct to cool the rear-end cylinder block. The left and right air guiding cover structures on both sides of the engine are the same and are symmetrically installed, thus ensuring that the four cylinder blocks obtain a uniform cooling effect, solving the problem of poor cooling effect of the rear-end cylinder block far from the air inlet end in the traditional air guiding cover cooling design, avoiding problems such as low engine combustion efficiency, risk of knocking, and deterioration of engine power and fuel economy caused by uneven temperature, and prolonging the service life of the engine.

[0015] The structure of the present invention is simple. By arranging a clamping plate inside the air guiding cover to form a nested layer, an interlayer air duct is formed. The cold air in the interlayer air duct is insulated by the clamping plate and will not be heated by the cylinder block at the front end, so that fresh cold air can be introduced to the cylinder block at the rear end to cool the rear-end cylinder block, achieving an effect of nearly independent cooling of the rear-end cylinder block. The overall structure of the air guiding cover is simple, facilitating production, manufacturing, and daily maintenance, and having low manufacturing, maintenance, and usage costs.

[0016] Compared with the traditional structure of adding an air inlet pipe and an air outlet pipe to the air guiding cover, the structure of the present invention hardly changes the windward area of the air guiding cover, can reduce air resistance, and reduces the energy loss caused by wind resistance during the operation of the engine.

[0017] The structure of the present invention can significantly improve the cooling uniformity of the front and rear cylinder blocks on both sides of the cylinder block of the four-cylinder two-stroke piston engine. Through analysis and comparison, compared with the existing traditional single-layer air guiding cover design, adopting the structure of the present invention can achieve a 24% increase in the heat transfer coefficient, a 24% reduction in temperature non-uniformity, and a 24% increase in cooling efficiency. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 The overall structure schematic diagram of a dual-channel series cooling structure for an aviation piston engine used in an unmanned aerial vehicle of the present invention installed on a four-cylinder two-stroke engine Figure 1 (Viewed from the air inlet side); Figure 2 The overall structure schematic diagram of a dual-channel series cooling structure for an aviation piston engine used in an unmanned aerial vehicle of the present invention installed on a four-cylinder two-stroke engine Figure 2 (Viewed from the air outlet side); Figure 3 The structure schematic diagram of the left air guide cover and the right air guide cover of the present invention Figure 1 (Viewed from the air inlet side); Figure 4 The structure schematic diagram of the left air guide cover and the right air guide cover of the present invention Figure 2 (Viewed from the air outlet side); Figure 5 The air flow schematic diagram of the left air guide cover and the right air guide cover of the present invention in the windward state.

[0020] In the figure: 1. Left air guide cover; 1-1. Air inlet of the left air guide cover; 1-2. Left clamping plate; 1-3. Left sandwich air duct; 1-4. Air inlet of the left sandwich air duct; 1-5. Air outlet of the left sandwich air duct; 1-6. Left main air duct; 1-7. Notch of the left air guide cover; 1-8. First main body part; 1-9. First convex part; 1-10. Spark plug installation hole of the left air guide cover; 1-11. Air outlet of the left air guide cover; 2. Right air guide cover; 2-1. Air inlet of the right air guide cover; 2-2. Right clamping plate; 2-3. Right sandwich air duct; 2-4. Air inlet of the right sandwich air duct; 2-5. Air outlet of the right sandwich air duct; 2-6. Right main air duct; 2-7. Notch of the right air guide cover; 2-8. Second main body part; 2-9. Second convex part; 2-10. Spark plug installation hole of the right air guide cover; 2-11. Air outlet of the right air guide cover; 3. First cylinder block; 4. Second cylinder block; 5. Third cylinder block; 6. Fourth cylinder block. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] An embodiment of a two-channel series cooling structure for an aviation piston engine of an unmanned aerial vehicle according to the present invention is as Figure 1 , Figure 2 and Figure 5 shown, including two air ducts, namely a left air duct 1 and a right air duct 2. The structures of the left air duct 1 and the right air duct 2 are completely mirror-symmetrical, made of the same material, and symmetrically installed outside the cylinder block of a four-cylinder two-stroke piston engine. The first cylinder block 3 and the second cylinder block 4 of the four-cylinder two-stroke piston engine are located on the same side, and the third cylinder block 5 and the fourth cylinder block 6 are located on the same side. The left air duct 1 is installed outside the first cylinder block 3 and the second cylinder block 4 on the left side of the four-cylinder two-stroke piston engine, and the right air duct 2 is installed outside the third cylinder block 5 and the fourth cylinder block 6 on the right side of the four-cylinder two-stroke piston engine. The left air duct 1 and the right air duct 2 are shell structures with a U-shaped cross-section, and the U-shaped openings of the two air ducts face each other, so that their U-shaped shells wrap the corresponding cylinder blocks, and are fixedly connected to the corresponding cylinder blocks through fasteners at their respective U-shaped openings. The end of the left air duct 1 close to the first cylinder block 3 is the air inlet 1-1 of the left air duct, and the other end far from its air inlet 1-1 is the air outlet 1-11 of the left air duct; the end of the right air duct 2 close to the third cylinder block 5 is the air inlet 2-1 of the right air duct, and the other end far from its air inlet 2-1 is the air outlet 2-11 of the right air duct. The left air duct 1 is used to introduce cold air to cool the first cylinder block 3 and the second cylinder block 4 in sequence, and the right air duct 2 is used to introduce cold air to cool the third cylinder block 5 and the fourth cylinder block 6 in sequence. The cylinder blocks close to the air inlet ends of the two air ducts are the front-end cylinder blocks, such as the first cylinder block 3 and the third cylinder block 5, and the cylinder blocks close to the air outlets of the two air ducts are the rear-end cylinder blocks, such as the second cylinder block 4 and the fourth cylinder block 6.

[0023] At the same time, referring to Figure 3 and Figure 4 , the clamping plate fixed inside the left air duct 1 is the left clamping plate 1-2. Specifically, the left clamping plate 1-2 is fixed at the inner layer of the left air duct 1 close to the air inlet 1-1 end of the left air duct. The left clamping plate 1-2 and the left air duct 1 are arranged in parallel, and a left sandwich air duct 1-3 is formed between them, which runs through along the air guiding direction. The air inlet 1-4 of the left sandwich air duct is flush with the air inlet 1-1 of the left air duct, and the air outlet 1-5 of the left sandwich air duct is located in the middle inside the left air duct 1 and is also located between the first cylinder block 3 and the second cylinder block 4. A left main air duct 1-6 is formed between the left clamping plate 12 and the first cylinder block 3.

[0024] Furthermore, the left air guide cover 1 is an integral thin-walled housing structure, which includes a first main body portion 1-8 and a first convex portion 1-9. There is an arc transition between the first main body portion 1-8 and the first convex portion 1-9. The overall profile of the left air guide cover 1 bulges outward at the installation position of the left clamping plate 1-2, forming a first convex portion 1-9 away from the first cylinder block 3, so that the left clamping plate 1-2 inside the left air guide cover 1 and the first main body portion 1-8 of the left air guide cover 1 are within the same contour surface, making the distance between the left clamping plate 1-2 and the first cylinder block 3 the same as the distance between the first main body portion 1-8 and the second cylinder block 4, which can ensure the smoothness of air guiding. At the same time, the first convex portion 1-9 and the left clamping plate 1-2 are parallel, and an equal-gap left sandwich air duct 1-3 is formed between the left clamping plate 1-2 and the first convex portion 1-9 of the left air guide cover 1. The air outlet 1-5 of the left sandwich air duct is located at the arc transition between the first main body portion 1-8 and the first convex portion 1-9 of the left air guide cover 1. In order to ensure the connection stability between the left clamping plate 1-2 and the left air guide cover 1 and stably space the distance between the two to ensure the ventilation volume of the sandwich air duct, a plurality of reinforcing ribs are provided between the left clamping plate 1-2 and the first convex portion 1-9 along the air guiding direction. The reinforcing ribs play a role in supporting and connecting the left clamping plate 1-2 and the first convex portion 1-9 of the left air guide cover 1.

[0025] The right air guide cover 2 and the left air guide cover 1 are mirror-symmetrical in structure. The clamping plate fixed inside the right air guide cover 2 is the right clamping plate 2-2. Specifically, the inner layer of the right air guide cover 2 is fixed with the right clamping plate 2-2 near the air inlet 2-1 end of the right air guide cover. The right clamping plate 2-2 and the right air guide cover 2 are parallel, and a right sandwich air duct 2-3 that penetrates along the air guiding direction is formed between the two. The air inlet 2-4 of the right sandwich air duct is flush with the air inlet 2-1 of the right air guide cover. The air outlet 2-5 of the right sandwich air duct is located in the middle of the inner side of the right air guide cover 2 and is also located between the third cylinder block 5 and the fourth cylinder block 6. A right main air duct 2-6 is formed between the right clamping plate 2-2 and the third cylinder block 5.

[0026] Further, the right air guide cover 2 is also an integral thin-walled housing structure, with its second main body portion 2-8 and second convex portion 2-9, and there is an arc transition between the second main body portion 2-8 and the second convex portion 2-9. The overall profile of the right air guide cover 2 bulges outward at the installation position of the right clamping plate 2-2, forming the second convex portion 2-9 away from the third cylinder block 5, so that the right clamping plate 2-2 inside the right air guide cover 2 and the second main body portion 2-8 of the right air guide cover 2 are in the same profile plane, making the distance between the right clamping plate 2-2 and the third cylinder block 5 the same as the distance between the second main body portion 2-8 and the fourth cylinder block 6, which can ensure the smoothness of air guiding. An equal-gap right sandwich air duct 2-3 is formed between the right clamping plate 2-2 and the second convex portion 2-9 of the right air guide cover 2, and the air outlet 2-5 of the right sandwich air duct is located at the arc transition between the second main body portion 2-8 and the second convex portion 2-9 of the right air guide cover 2. Similarly, a plurality of reinforcing ribs are provided between the right clamping plate 2-2 and the second convex portion 2-9 along the air guiding direction to ensure the connection stability between the right clamping plate 2-2 and the right air guide cover 2, and to stably space the distance between the two, ensure the ventilation volume of the sandwich air duct, and the reinforcing ribs support and connect the right clamping plate 2-2 and the second convex portion 2-9 of the right air guide cover 2.

[0027] When the two air guide covers work, the cold air at the air inlet of the left air guide cover 1 is divided into two paths. The cold air entering the left main air duct 1-6 cools the first cylinder block 3 and the second cylinder block 4 in sequence. The cold air entering the left sandwich air duct 1-3 is converged into the left main air duct 1-6 from the air outlet 1-5 of the left sandwich air duct, and cools the second cylinder block 4 after converging with the cold air flowing through the first cylinder block 3. Although the cold air flowing through the first cylinder block 3 in the left main air duct 1-6 will be heated due to taking away the heat of the first cylinder block 3, at the second cylinder block 4, due to the fresh cold air converging from the air outlet 1-5 of the left sandwich air duct, exclusive fresh cold air is introduced to the second cylinder block 4, ensuring the effective cooling of the second cylinder block 4. The cold air after cooling the second cylinder block 4 is then discharged from the air outlet 1-11 of the left air guide cover 1.

[0028] The cold air at the air inlet of the right air guide cover 2 is divided into two paths. The cold air entering the right main air duct 2-6 cools the third cylinder block 5 and the fourth cylinder block 6 in sequence. The cold air entering the right sandwich air duct 2-3 is converged into the right main air duct 2-6 from the air outlet 2-5 of the right sandwich air duct, and cools the fourth cylinder block 6 after converging with the cold air flowing through the third cylinder block 5. Although the cold air flowing through the third cylinder block 5 in the right main air duct 2-6 will be heated due to taking away the heat of the third cylinder block 5, at the fourth cylinder block 6, due to the fresh cold air converging from the air outlet 2-5 of the right sandwich air duct, exclusive fresh cold air is introduced to the fourth cylinder block 6, thereby ensuring the effective cooling of the fourth cylinder block 6. The cold air after cooling the fourth cylinder block 6 is then discharged from the air outlet 2-11 of the right air guide cover 2.

[0029] The structural designs of the left air deflector 1 and the right air deflector 2 need to avoid the exhaust ports of the engine block and the spark plugs connected to the block. Therefore, two notches 1-7 for avoiding the exhaust ports of the first cylinder block 3 and the second cylinder block 4 are provided on one side of the U-shaped opening of the left air deflector 1, and two notches 2-7 for avoiding the exhaust ports of the third cylinder block 5 and the fourth cylinder block 6 are provided on one side of the U-shaped opening of the right air deflector 2. Correspondingly, corresponding notches for avoiding the exhaust ports of the cylinder block are also provided on the clamping plates on the inner layers of the two air deflectors. Four spark plug mounting holes are provided on the left air deflector 1 for avoiding the spark plugs mounted on the first cylinder block 3 and the second cylinder block 4. Four spark plug mounting holes are also provided on the right air deflector 2 for avoiding the spark plugs mounted on the third cylinder block 5 and the fourth cylinder block 6. Correspondingly, corresponding spark plug mounting holes for avoiding the spark plugs are also provided on the clamping plates on the inner layers of the two air deflectors.

[0030] The present invention provides an air deflector with bilateral balanced cooling. An annular sandwich channel covering a single cylinder block at the front end of the air deflector is added at the air inlet front end of the air deflector, so as to introduce fresh cold air in the sandwich layer into the cylinder block at the air inlet rear end, thereby achieving an effect of nearly independent cooling of the cylinder block at the rear end in a limited space. Through the synergistic effect of the main air duct and the sandwich air supply, direct and efficient cooling of the first cylinder is achieved, and the inter-cylinder balanced cooling effect of optimized mixed cooling for the secondary cylinders is realized, solving the problem of uneven cooling effect brought by the traditional cooling design and improving the overall cooling efficiency.

[0031] Through the collaborative work of the main air duct and the sandwich air duct of the air deflector of the present invention, the problem of uneven temperature in the traditional single channel is eliminated. It can be seen from the following analysis that the effect of the present invention is significantly better than that of the traditional single-layer air deflector.

[0032] Comparison of improvement in temperature standard deviation: ( ) In the formula, is the temperature standard deviation (non-uniformity) of the double-layer air deflector of the present invention; is the temperature standard deviation (non-uniformity) of the traditional single-layer air deflector; is the cross-sectional area ratio of the sandwich air duct to the main air duct, is the cross-sectional area of the sandwich air duct, is the cross-sectional area of the main air duct.

[0033] When = 0.3, the temperature standard deviation (non-uniformity) of the structure of the present invention is reduced by 24%.

[0034] Enhancement of heat transfer coefficient: Turbulent superposition effect of the double air deflector channels of the structure of the present invention:

[0035] In the formula, is the heat transfer coefficient of the structure of the present invention, is the heat transfer coefficient of the main air duct (i.e., the heat transfer coefficient of the traditional single-layer air guide cover); Interlayer flow velocity 2 = , where 2 is the flow velocity of the interlayer air duct, is the flow velocity of the main air duct, and the heat transfer is enhanced by increasing the contact area and the turbulence intensity.

[0036] Quantification of cooling efficiency:

[0037] where is the cooling efficiency of the double-layer air guide cover of the present invention, is the cooling efficiency of the traditional single-layer air guide cover, is the heat transfer coefficient of the interlayer air duct. When = 0.3, the cooling efficiency of the structure of the present invention is increased by 24%.

[0038] By optimizing the cross-sectional area ratio of the interlayer air duct and the main air duct, the cooling performance, pressure loss, and space cost are balanced: 1 + 0.8 ) - 1 + 0.15) -

[0039] where is the cooling effect of the structure of the present invention, is the weight of the cooling performance, is the weight of the pressure loss, is the space weight. During the design process, the weight design is adjusted according to the design priority value: (1) Cooling priority: = 1, = 0.5, = 0.3, (2) Space priority: is increased to 0.5, For Derivation gives: where is the optimal value of when cooling is prioritized; When cooling is prioritized, 0.28( .28 ); When space is prioritized, can be reduced to 0.15.

[0040] Engineering constraint correction: The final value needs to meet the assembly limit: where For the final value of is the maximum outer diameter of the air guide cover, and is the inner diameter of the air guide cover. For example, when the outer diameter is allowed to increase by 20%, is the maximum value of

[0041] Based on the above analysis, the comparison table of the air guiding effect of the structure of the present invention and the performance of the traditional single-layer air guide cover is as follows:

[0042] In the table, is the temperature gradient.

[0043] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dual-channel series cooling structure for an aviation piston engine of an unmanned aerial vehicle, comprising two air guide covers arranged symmetrically with respect to a four-cylinder two-stroke piston engine. One air guide cover is installed outside the two cylinder blocks on the left side of the four-cylinder two-stroke piston engine, and the other air guide cover is installed outside the two cylinder blocks on the right side of the four-cylinder two-stroke piston engine. It is characterized in that a clamping plate is fixed at the inner layer of the air guide cover near the air inlet end of the air guide cover. The clamping plate is parallel to the air guide cover, and a sandwich air duct running through along the air guiding direction is formed between the two. The air inlet of the sandwich air duct is flush with the air inlet of the air guide cover, and the air outlet of the sandwich air duct is located in the middle of the inner side of the air guide cover and between the two cylinder blocks on the side where the air guide cover is installed; a main air duct is formed between the clamping plate and the cylinder block. Among them, the cold air entering the main air duct from the air inlet of the air guide cover cools the front and rear two cylinder blocks on the side where the air guide cover is installed in sequence. The cold air entering the sandwich air duct from the air inlet of the sandwich air duct converges into the main air duct from the air outlet of the sandwich air duct, and after converging with the cold air flowing through the front-end cylinder block, cools the rear-end cylinder block.

2. The dual-channel series cooling structure of the aviation piston engine for drones according to claim 1, wherein, The air guide cover is a shell structure with a U-shaped cross-section. The U-shaped openings of the two air guide covers face each other, so that their U-shaped shells wrap the corresponding cylinder blocks, and are fixedly connected to the corresponding cylinder blocks through fasteners at their respective U-shaped openings.

3. The dual-channel series cooling structure of the aircraft piston engine for drones according to claim 2, wherein, Notches for avoiding the exhaust ports of the cylinder blocks are provided on one side of the U-shaped openings of the two air guide covers; corresponding notches for avoiding the exhaust ports of the cylinder blocks are also provided on the corresponding clamping plates at the corresponding positions.

4. The dual-channel series cooling structure of the aviation piston engine for drones according to claim 1, characterized in that, The air guide cover includes an integral main body part and a convex part. The main body part and the convex part are transitioned by an arc surface; the overall profile of the air guide cover is convex at the installation position of the clamping plate, forming a convex part away from the front-end cylinder block, so that the clamping plate inside the air guide cover and the main body part of the air guide cover are on the same profile surface, and the distance between the clamping plate and the front-end cylinder block is the same as the distance between the main body part and the rear-end cylinder block; an equal-gap sandwich air duct is formed between the clamping plate and the convex part of the air guide cover, and the air outlet of the sandwich air duct is located at the arc transition between the main body part and the convex part of the air guide cover.

5. The dual-channel series cooling structure of the aviation piston engine for drones according to claim 4, wherein, A plurality of reinforcing ribs are arranged between the clamping plate and the convex part along the air guiding direction. The reinforcing ribs between the clamping plate and the convex part are used to support and connect the clamping plate and the convex part of the air guide cover.

6. The dual-channel series cooling structure of the aviation piston engine for drones according to claim 1, characterized in that, A plurality of spark plug mounting holes are provided on the air guide cover for avoiding the spark plugs installed on the cylinder block, and corresponding mounting holes for avoiding the spark plugs are also provided on the corresponding clamping plates at the corresponding positions.

7. The dual-channel series cooling structure of the aviation piston engine for drones according to claim 1, wherein, The two air guide covers are made of the same material.

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