A leakage-proof structure of an in-line piston engine, an engine and an aircraft thereof

Abstract

The utility model relates to the technical field of engine oil pan, especially a leakage-proof structure of in-line piston engine, an engine and an aircraft, including setting in the oil pan of engine crankcase body subassembly lower part, the oil pan forms a basin -like structure of one inner bottom surface basically level, the inner bottom surface of oil pan is concave downward and forms the oil storage groove that the structure is further outward protruding relative to the outer bottom surface of oil pan, the outer bottom surface of oil pan and the outside wall between oil storage groove smooth transition, the sealing edge contact surface of oil pan and engine crankcase body subassembly connection is wide side design, and is installed on the sealing edge contact surface with wide -side sealing pad, and the width of wide -side sealing pad is greater than the width of sealing edge contact surface, the utility model simplifies the structure, makes can adapt to the large inclination angle of aircraft ±45 DEG movement, greatly reduces the oil leakage risk simultaneously.

Description

Technical Field

[0001] This utility model relates to the field of engine oil pan technology, specifically to a leak-proof structure for an inline piston engine, the engine, and its aircraft. Background Technology

[0002] In recent years, drones using 4-cylinder piston engines directly driving propellers, typical of small manned aircraft, have gradually entered the market. However, the vast majority of these engines are horizontally opposed, and the application of drones equipped with inline 4-cylinder piston engines remains relatively limited. In the fields of large industrial drones and small manned aircraft, the main technical challenge facing inline 4-cylinder piston engines lies in their large dimensions, including height and length, which directly affects their compatibility with aircraft installation. Although improved small inline piston engines exist, their oil pan design has significant flaws: to meet various functional requirements, the oil pan structure is overly complex, leading to oil leakage during actual operation. This leakage not only causes oil loss but may also contaminate other aircraft components, affecting flight safety. Furthermore, existing oil pan designs are insufficient in terms of sealing performance and structural strength, making it difficult to meet the requirements of inline piston engines in special application scenarios such as drones. Therefore, existing technologies urgently need improvement to address these issues. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a leak-proof structure for an inline piston engine, the engine and its aircraft.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a leak-proof structure for an inline piston engine, comprising an oil pan disposed at the lower part of the engine crankcase assembly, the oil pan being formed as a basin-shaped structure with a basically horizontal inner bottom surface, the inner bottom surface of the oil pan being recessed downward to form an oil reservoir that protrudes further outward relative to the outer bottom surface of the oil pan, the outer bottom surface of the oil pan and the outer side wall of the oil reservoir having a smooth transition, the sealing edge contact surface connecting the oil pan and the engine crankcase assembly having a wide edge design, and a wide edge sealing gasket being installed on the sealing edge contact surface, the width of the wide edge sealing gasket being greater than the width of the sealing edge contact surface.

[0005] In some embodiments, the oil reservoir is located at the center of the oil pan.

[0006] In some embodiments, the bottom of the oil storage tank is provided with a through-hole for draining oil, and a draining bolt is sealed in the draining oil hole.

[0007] In some embodiments, a plurality of reinforcing ribs are provided on the smooth connection surface between the upper inner side of the oil pan and the oil storage tank.

[0008] In some embodiments, a reinforcing rib plate is provided between the inner bottom of the oil storage tank and the side wall of the oil storage tank.

[0009] In some embodiments, the inner surface of the oil pan and the inner sidewall of the oil reservoir form a smooth transition.

[0010] In some embodiments, a plurality of assembly bolts for assembling with the engine crankcase assembly are evenly arranged on the upper sealing edge contact surface of the oil pan. Each assembly bolt has a plurality of anti-loosening safety holes on its head, and all assembly bolts are sequentially arranged through the corresponding anti-loosening safety holes.

[0011] To achieve the above objectives, this utility model also provides the following technical solution: an engine equipped with any of the aforementioned leak-proof structures.

[0012] To achieve the above objectives, the present invention also provides the following technical solution: an aircraft equipped with the aforementioned engine.

[0013] Compared with the prior art, the beneficial effects of this utility model are: by using a wide-edge sealing gasket, optimizing the oil reservoir structure and exhaust pipe channel design, it solves the leakage problem caused by insufficient sealing performance and complex structure of the existing oil pan. It has the advantages of improving sealing performance, reducing oil consumption, enhancing structural stability and adaptability. The introduction of a wide-edge oil pan sealing gasket can adapt to the large tilt angle ±45° movement of the aircraft.

[0014] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. The embodiments of this application will provide a detailed description and understanding of the application. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the oil pan structure of this utility model;

[0016] Figure 2 This is a schematic diagram of the oil pan and wide-edge sealing gasket of this utility model.

[0017] Figure 3 This is a schematic diagram of the structure of the present invention. Figure 3 ;

[0018] Figure 4 This is a front view of the present invention;

[0019] Figure 5 This is a schematic diagram showing the fit between the oil pan and the exhaust pipe.

[0020] In the diagram: 1. Oil pan; 2. Oil reservoir; 3. Sealing edge contact surface; 4. Wide edge sealing gasket; 5. Exhaust pipe passage; 6. Drain bolt; 7. Reinforcing rib plate one; 8. Reinforcing rib plate two; 9. Assembly bolt. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] In existing technologies, 4-cylinder piston engines for small manned aircraft are mostly arranged horizontally opposed, but inline 4-cylinder piston engines are difficult to install due to their large size. Existing improved inline engines have complex oil pan structures and excessive functional integration, which often leads to oil leaks in actual use, affecting the reliability of aircraft operation.

[0023] To address the aforementioned issues and the oil leakage defects caused by the complex structure of the oil pan, the first step is to simplify the overall structure of the oil pan. Analysis of the leakage point distribution revealed that sealing failures are mainly concentrated at the connection points between the pan and the transition structure between the oil storage area and the casing. Therefore, while maintaining basic oil storage functionality, the geometry of the casing is optimized, with a focus on enhancing the structural reliability of the sealing contact surfaces.

[0024] Therefore, as Figures 1 to 4 As shown, this application proposes a leak-proof structure for an inline piston engine, including an oil pan 1 located at the lower part of the engine crankcase assembly. The oil pan 1 is formed into a basin-shaped structure with a basically horizontal inner bottom surface. The inner bottom surface is recessed downward to form an oil reservoir 2. The oil reservoir 2 structure protrudes further outward relative to the outer bottom surface. There is a smooth transition between the outer bottom surface and the outer wall of the oil reservoir 2. The sealing edge contact surface 3 connecting the oil pan 1 and the engine crankcase assembly is designed with a wide edge and a wide edge sealing gasket 4 is installed. The width of the wide edge sealing gasket 4 is greater than the width of the sealing edge contact surface 3. At the same time, the outer edge of the wide edge sealing gasket 4 is flush with the outer edge of the sealing edge contact surface 3.

[0025] The oil reservoir 2 refers to the recessed area below the inner bottom surface, which can be manufactured using a stamping process. Its convex structure increases the oil storage capacity without changing the overall installation dimensions of the oil pan 1. The wide-edge sealing gasket 4 refers to a continuous sealing element covering the entire sealing edge. It can be made of multi-layer composite rubber material, which increases the contact area and improves the sealing reliability. At the same time, the wide-edge sealing gasket design can adapt to the large tilt angle ±45° movement of the aircraft.

[0026] Specifically, the oil pan 1 adopts a combination structure of a horizontal inner bottom surface and a recessed oil reservoir 2, maintaining the oil storage function while reducing the overall height. The outward-protruding design of the oil reservoir 2 creates an outward-extending cavity at the bottom, avoiding any additional increase in the height of the housing. The wide-edge sealing contact surface, in conjunction with the composite sealing gasket, forms a continuous sealing band, effectively covering the weak connection points in traditional structures.

[0027] Compared to existing technologies, current oil pans typically employ a multi-layered stepped oil storage structure, resulting in stress concentration points at the transition areas between functional zones. This solution simplifies the shell geometry and reduces potential leakage points through a single-layer recessed oil storage groove and a smooth transition structure. Traditional sealing designs use a narrow-edge contact surface with a single-layer gasket; this solution's wide-edge sealing structure significantly increases the effective contact area of ​​the sealing material.

[0028] Through the above technical solutions, this application effectively solves the oil leakage problem of the complex structure oil pan 1, reduces the processing difficulty by optimizing the shape of the oil storage area, and improves the sealing reliability of the connection parts by using a wide-edge sealing design.

[0029] This application further proposes that the oil storage tank 2 be located at the center of the oil pan 1.

[0030] The central position refers to the point where, when the oil pan 1 is installed under the engine crankcase assembly, the projected area of ​​the oil reservoir 2 on the bottom inner surface of the oil pan 1 coincides with the geometric center point of the oil pan 1. Specifically, this can be achieved by aligning the axis of symmetry of the oil reservoir 2 with the longitudinal centerline of the oil pan 1 along its length. This position creates a symmetrical layout of the oil reservoir 2 relative to the overall structure of the oil pan 1. During engine operation, this balances the oil flow path and vibration transmission direction, reducing localized oil accumulation or uneven distribution caused by vibration.

[0031] Specifically, the oil reservoir 2 forms a recessed area in the center of the oil pan 1. The volume of this recessed area is defined by the depth of the inner bottom surface of the oil pan 1 and the outward convex structure of the outer bottom surface. When the engine is running, the oil splashed into the oil pan 1 is drawn towards the central area by gravity. The recessed depth of the oil reservoir 2 and the outward convex structure form a three-dimensional space, which can limit the lateral displacement of the oil under vibration conditions. At the same time, the symmetrical layout of the oil reservoir 2 ensures that the flow path length of the oil on both sides of the width direction of the oil pan 1 is equal, avoiding oil distribution imbalance caused by differences in flow paths.

[0032] Compared to existing technologies, the oil reservoir 2 of a conventional oil pan 1 is typically located near the crankcase, causing the oil to shift and accumulate to one side when the engine vibrates, easily forming localized high-pressure areas at the sealing edge. The centrally located design of this application ensures that the oil is evenly distributed inside the oil reservoir 2 under vibration conditions, reducing the risk of leakage at the sealing edge due to uneven oil pressure distribution, while also improving collection efficiency by shortening the oil return path.

[0033] Through the above technical solution, this application effectively solves the problem of unbalanced oil distribution caused by the asymmetrical structure of the oil pan 1 in inline piston engines. By optimizing the geometric position of the oil reservoir 2, the oil flow path and vibration response characteristics are balanced, and the leak-proof performance of the sealing edge is improved while ensuring the oil storage volume, thereby enhancing the engine's operational reliability under UAV-borne operating conditions.

[0034] At the same time, such as Figure 5 As shown, the vertical space between the horizontal plane of the outer bottom surface of the oil reservoir 2 and the outer bottom surface of the oil pan 1 forms the installation space for the exhaust pipe. This allows the exhaust pipe to pass through both sides of the outer surface of the oil reservoir 2, avoiding direct installation at the bottom of the oil pan 1 as in the traditional method. This effectively shortens the height of the entire engine crankcase assembly, improves subsequent assembly efficiency, and significantly saves installation space.

[0035] This application further proposes that the bottom of the oil storage tank 2 is provided with a through oil drain hole, and an oil drain bolt 6 is sealed in the oil drain hole.

[0036] The drain hole is a channel that runs through the bottom of the oil reservoir 2 to drain engine oil. It can be formed into a through hole using machining or casting processes, and its function is to provide a direct passage for oil changes. The drain bolt 6 is a threaded fastener with a sealing structure. It can be made of metal material, machined into an externally threaded cylindrical body, and fitted with a sealing ring. Its function is to seal the drain hole together with the sealing ring through the threaded connection, preventing oil leakage.

[0037] Specifically, the bottom of the oil reservoir 2 has a through hole for draining waste oil. The drain bolt 6 is installed in the hole via a threaded connection, and a sealing ring is placed between the bolt head and the hole to form a sealing interface. When the engine oil needs to be changed, the drain bolt 6 is unscrewed to release the waste oil, and after the operation is completed, it is screwed back in and sealed again by the sealing ring. This structure simplifies the oil draining function design of the oil pan 1 through the combination of a single drain hole and a removable bolt.

[0038] Compared to existing technologies, traditional oil pan drain structures typically rely on multiple dispersed drain ports or complex piping, resulting in numerous sealing surfaces and inconvenient maintenance. This solution reduces the number of potential leak points by centrally arranging the drain holes and using bolt seals, while also lowering the installation space requirements.

[0039] Through the above technical solution, this application realizes centralized control of oil draining operation, avoids oil leakage caused by multi-hole seal failure, simplifies maintenance process and reduces the risk of oil residue.

[0040] This application further proposes that a number of reinforcing ribs 7 are provided on the smooth connection surface between the upper part of the oil pan 1 and the oil storage tank 2.

[0041] Among them, the reinforcing rib 7 refers to a triangular plate-shaped structure set in the transition area of ​​the inner surface of the oil pan 1. It can be realized by stamping, welding assembly, machining, casting, etc., and its thickness can be 1.5-3 times the thickness of the oil pan 1 body material. This feature is used to improve the deformation resistance of the oil pan 1 connection surface and prevent deformation of the sealing edge contact surface 3 due to engine vibration.

[0042] Specifically, in the transition area between the sealing edge contact surface 3 at the top of the oil pan 1 and the outer wall of the oil reservoir 2, several transversely arranged reinforcing ribs 7 are distributed circumferentially at equal or non-equal intervals. These reinforcing ribs 7 form a support structure with the oil pan 1 body, and suppress local deformation of the connection surface area by dispersing mechanical loads during engine operation, thereby maintaining the flatness of the sealing edge contact surface 3.

[0043] Compared with existing technologies, the sealing edge contact surface 3 of a traditional oil pan 1 usually lacks a reinforcing structure or only has a reinforcing structure in some areas. Under high-frequency vibration of the engine, it is prone to warping deformation, resulting in uneven pressure on the sealing gasket and the formation of leakage channels. This solution improves the bending stiffness of the connection surface area by adding a reinforcing rib plate 7, while maintaining the same material thickness, and the overall weight of the oil pan 1 does not increase significantly.

[0044] Through the above technical solution, this application effectively solves the leakage problem caused by the deformation of the sealing surface of the oil pan 1 of the inline engine. The key is to suppress the deformation of the sealing surface caused by vibration through the local reinforcement structure, thereby ensuring that the wide-side sealing gasket 4 maintains uniform compression contact under all engine operating conditions.

[0045] This application further proposes that a reinforcing rib plate 28 is provided between the bottom of the oil storage tank 2 and the side wall of the oil storage tank 2.

[0046] Among them, the reinforcing rib 2 refers to the triangular plate-shaped support structure located in the area where the bottom of the oil storage tank 2 connects to the side wall. It can be made by machining or casting in one piece, and is used to disperse the stress inside the oil storage tank 2 caused by oil pressure or external mechanical load. The side wall of the oil storage tank 2 refers to the annular wall structure that extends upward around the bottom of the oil storage tank 2. It can be formed by stamping or casting processes, and is used to define the boundary of the oil storage tank 2 and withstand the static pressure of the internal oil.

[0047] Specifically, the second reinforcing rib 8 is arranged in the angled area between the bottom and sidewall of the oil reservoir 2, and its extension direction is parallel to the longitudinal axis of the oil reservoir 2. The cross-sectional shape of the second reinforcing rib 8 can also be designed as triangular, trapezoidal, or rectangular, and its top edge is flush with the inner surface of the sidewall of the oil reservoir 2. By continuously welding or integrally forming the contact surfaces of the second reinforcing rib 8 with the bottom and sidewall of the oil reservoir 2, a stable triangular support area can be formed, thereby suppressing the local deformation of the oil reservoir 2 under engine vibration or temperature changes.

[0048] Compared with existing technologies, the connection between the bottom and sidewall of the oil reservoir 2 of the existing oil pan 1 is usually a smooth transition surface without support, which is prone to stress concentration and weld cracking when subjected to long-term engine vibration. In contrast, this solution improves the original single-layer plate structure into a composite structure with an internal support frame by adding a reinforcing rib plate 8, which significantly improves the fatigue resistance of the oil reservoir 2.

[0049] Through the above technical solution, this application effectively reduces the deformation of the connection area between the bottom and side wall of the oil reservoir 2, avoids the problem of uneven distribution of sealing gasket clamping force caused by local stress concentration, and thus reduces the risk of oil leakage at the connection between the oil pan 1 and the engine crankcase assembly.

[0050] This application further proposes that the inner surface of the oil pan 1 and the inner wall of the oil storage tank 2 have a smooth transition.

[0051] The inner surface refers to the surface of the cavity inside the oil pan 1 that holds the engine oil. This can be achieved by casting or stamping to create a smooth surface, preventing localized turbulence or stagnation of the oil during flow. The inner wall of the oil reservoir 2 refers to the transition area connecting the oil reservoir 2 and the inner surface of the oil pan 1. This can be achieved using a curved, rounded surface structure to eliminate the stress concentration risk associated with right angles or sharp corners. A smooth transition refers to a connection between the inner surface and the inner wall of the oil reservoir 2 without sharp corners or creases. This can be achieved by molding or machining to create a continuous curved surface, reducing the risk of oil residue and leakage.

[0052] Specifically, the inner surface of the oil pan 1 is connected to the inner wall of the oil reservoir 2 by a continuous curved surface, allowing the oil to flow smoothly into the oil reservoir 2 and avoiding oil splashing or localized accumulation caused by sharp edges. During engine operation, the smoothness of the curved surface reduces the frictional resistance between the oil and the wall surface, while also reducing the risk of structural deformation caused by vibration or thermal expansion and contraction. The wide-edge design of the sealing edge contact surface 3, combined with the smooth transition structure, further reduces the probability of gasket failure due to uneven local stress.

[0053] Compared to existing technologies, traditional oil pan 1 and oil reservoir 2 are typically connected at right angles or with a slight chamfer between them and the inner surface. Such structures are prone to forming oil residue areas at the connection points, which can lead to sludge buildup or gasket wear after long-term use. In contrast, the rounded transition design eliminates sharp corners, reducing the possibility of oil retention and enhancing the overall structural strength, thus preventing cracks or leaks caused by stress concentration.

[0054] Through the above technical solution, this application effectively improves the flow characteristics of the oil inside the oil pan 1, reduces the risk of leakage caused by local oil stagnation, and enhances the structural stability of the connection area between the oil reservoir 2 and the oil pan 1, reducing the probability of sealing failure caused by structural deformation or stress concentration of the sealing gasket.

[0055] This application further proposes that a plurality of assembly bolts for assembling with the engine crankshaft housing assembly are uniformly arranged on the upper sealing edge contact surface 3 of the oil pan 1. Each assembly bolt has a plurality of anti-loosening safety holes on its head, and all assembly bolts are sequentially arranged through the corresponding anti-loosening safety holes.

[0056] The sealing edge contact surface 3 refers to the edge area connecting the oil pan 1 and the engine crankcase assembly. This can be achieved using a planar machining process, increasing the contact area to improve the sealing gasket's compression effect. The assembly bolts are the connecting parts used to fasten the oil pan 1 to the engine crankcase assembly. These can be hexagonal bolts with anti-loosening structures, ensuring even distribution to prevent excessive localized stress that could lead to seal failure. "Uniform arrangement" refers to the evenly spaced arrangement along the sealing edge contact surface 3, achieved using symmetrically distributed mounting holes to balance assembly stress and ensure the flatness of the sealing edge.

[0057] Specifically, the oil pan 1 is connected to the engine crankcase assembly by multiple mounting bolts, which are symmetrically and equidistantly arranged on the sealing edge contact surface 3. During assembly, the gasket is uniformly compressed between the contact surfaces of the oil pan 1 and the engine crankcase assembly, and the preload applied by each bolt forms a continuous sealing pressure band through uniform distribution. This arrangement ensures that the oil pan 1 is subjected to balanced stress, avoiding deformation of the sealing edge or damage to the gasket due to localized stress concentration.

[0058] Compared to existing technologies, traditional oil pan bolts are typically arranged asymmetrically or in insufficient numbers, which can easily lead to sealing pressure fluctuations under vibration. This solution optimizes the bolt distribution density and position to form a stable annular pressure distribution, effectively offsetting the impact of periodic vibrations during engine operation on sealing performance.

[0059] Through the above technical solution, this application solves the oil leakage problem caused by uneven force on the sealing surface of the oil pan 1 of an inline piston engine. By forming a stable sealing pressure distribution through evenly distributed assembly bolts, the risk of fatigue failure of the sealing gasket due to local overload is reduced, and the fastening force control process during assembly is simplified.

[0060] Meanwhile, to adapt to the operating conditions of the unmanned aerial vehicle and to prevent the assembly bolts from loosening, multiple anti-loosening safety holes are provided on the head of each assembly bolt. All assembly bolts are sequentially installed through the corresponding anti-loosening safety holes, connecting the assembly bolts together to form a rigid constraint, preventing the assembly bolts from loosening, and significantly improving the vibration resistance and sealing reliability of the connection structure.

[0061] This embodiment also provides an engine equipped with any of the above-mentioned leak-proof structures, which is applied to the engine of an unmanned aerial vehicle.

[0062] The leak-proof structure refers to the leak-proof structure installed inside the oil pan at the bottom of the engine crankcase assembly. The engine on the unmanned aerial vehicle (UAV) refers to a power unit suitable for low-altitude flight and requiring a compact layout. Specifically, it can be implemented using an inline four-cylinder piston engine. By optimizing the leak-proof structure design inside the oil pan, the overall height can be reduced to meet the installation requirements of the UAV, while ensuring the UAV can move at large tilt angles of ±45°.

[0063] In unmanned aerial vehicle (UAV) applications, this engine can adapt to the requirements of compact space layouts, improving its adaptability to UAVs.

[0064] This embodiment also provides an aircraft equipped with any of the engines described above.

[0065] An aircraft is an aerial vehicle that includes a power system, fuselage, and control system. It can be implemented using a multi-rotor or fixed-wing configuration and is equipped with an engine to provide flight power. The engine is an inline four-cylinder piston engine with a leak-proof structure.

[0066] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A leak-proof structure for an inline piston engine, comprising an oil pan (1) disposed at the lower part of the engine crankcase assembly, characterized in that: The oil pan (1) is formed as a basin-shaped structure with a basically horizontal inner bottom surface. The inner bottom surface of the oil pan (1) is recessed downward to form an oil reservoir (2) that protrudes further outward relative to the outer bottom surface of the oil pan (1). The outer bottom surface of the oil pan (1) and the outer side wall of the oil reservoir (2) are smoothly transitioned. The sealing edge contact surface (3) connecting the oil pan (1) and the engine crankcase assembly is designed with a wide edge, and a wide edge sealing gasket (4) is installed on the sealing edge contact surface (3). The width of the wide edge sealing gasket (4) is greater than the width of the sealing edge contact surface (3).

2. The leak-proof structure for an inline piston engine according to claim 1, characterized in that: The oil storage tank (2) is located at the center of the oil pan (1).

3. A leak-proof structure for an inline piston engine according to claim 1 or 2, characterized in that: The bottom of the oil storage tank (2) is provided with a through-hole for draining oil, and a draining bolt (6) is sealed in the draining oil hole.

4. The leak-proof structure for an inline piston engine according to claim 1, characterized in that: Several reinforcing ribs (7) are provided on the smooth connection surface between the upper inner side of the oil pan (1) and the oil storage tank (2).

5. The leak-proof structure for an inline piston engine according to claim 1, characterized in that: A reinforcing rib plate 2 (8) is provided between the inner bottom of the oil storage tank (2) and the side wall of the oil storage tank (2).

6. The leak-proof structure for an inline piston engine according to claim 1, characterized in that: The inner surface of the oil pan (1) and the inner sidewall of the oil storage tank (2) are smoothly transitioned.

7. The leak-proof structure for an inline piston engine according to claim 1, characterized in that: The upper sealing edge contact surface (3) of the oil pan (1) is uniformly provided with a number of assembly bolts for assembling with the engine crankshaft housing assembly. Each assembly bolt has a number of anti-loosening safety holes on its head, and all assembly bolts are sequentially installed through the corresponding anti-loosening safety holes.

8. An engine, characterized in that, It is equipped with a leak-proof structure according to any one of claims 1-7.

9. An aircraft, characterized in that, It is equipped with the engine as described in claim 8.

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