Oil return structure of an in-line piston engine, engine and aircraft thereof

Abstract

The utility model relates to the technical field of engine oil pan, especially an oil return structure of in-line piston engine, an engine and an aircraft, including setting in the lower part of engine crankcase body subassembly's oil pan, 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 upper part inboard of oil pan is provided with the oil return interface, the upper end of oil return interface is connected with the oil return device in the engine crankcase body subassembly and its engine oil return pipeline system, the lower end of oil return interface is connected with the stepped surface higher than the oil storage groove in the oil pan interior, the oil return interface adopts the C -shaped opening design of cross section, and the C -shaped opening of oil return interface is communicated with the oil storage groove through the stepped surface, the utility model adds the oil return pipe interface, and the oil return buffer is introduced into the oil storage groove, which avoids the impact on the oil storage groove directly.

Description

Technical Field

[0001] This utility model relates to the field of engine oil pan technology, specifically to an oil return 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 from 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 the engine's compatibility with the aircraft. Although improved small inline piston engines exist, the design of their oil pan has significant flaws. Engine oil is directly fed back into the reservoir when returning to the oil pan. However, this direct return causes oil to splash and impact within the reservoir. This splashing not only generates noise and vibration but also leads to excessive contact between the oil and air, causing oxidation and deterioration, and may also cause oil foaming, severely affecting the normal operation of the lubrication system. Furthermore, existing oil return structure designs often neglect the guidance of oil flow within the oil pan, resulting in an unclear oil return path, affecting engine lubrication efficiency and service life. To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide an oil return 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: an oil return 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, an oil return interface being provided on the upper inner side of the oil pan, the upper end of the oil return interface being connected to the oil return device and its engine oil return pipeline system in the engine crankcase assembly, the lower end of the oil return interface being connected to a stepped surface inside the oil pan that is higher than the oil reservoir, the oil return interface adopting a C-shaped opening design, the C-shaped opening of the oil return interface communicating with the oil reservoir through the stepped surface.

[0005] In some embodiments, an oil guide plate is vertically arranged inside the oil pan, above the oil storage tank, corresponding to the oil return interface.

[0006] In some embodiments, one end of the oil guide plate is connected to the opening edge of the C-shaped opening of the oil return port near the oil reservoir.

[0007] In some embodiments, the center hole connecting the stepped surface inside the oil pan, which is higher than the oil storage tank, to the return oil interface is designed as a recessed hole.

[0008] In some embodiments, the recessed hole and the stepped surface inside the oil pan that is higher than the oil reservoir form a smooth transition.

[0009] To achieve the above objectives, this utility model also provides the following technical solution: an engine equipped with any of the oil return structures described above.

[0010] To achieve the above objectives, the present invention also provides the following technical solution: an aircraft equipped with the aforementioned engine.

[0011] Compared with the prior art, the beneficial effects of this utility model are: the orderly return of engine oil is achieved through the combination of the stepped surface and the C-shaped opening oil return interface, and splashing is suppressed through the oil reservoir and the flow guiding component. It has a reasonable structural design, which can effectively reduce engine oil impact splashing, reduce noise and vibration, avoid engine oil oxidation and deterioration and foaming, and improve the working efficiency and service life of the lubrication system.

[0012] 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

[0013] Figure 1 This is a schematic diagram of the structure of this utility model;

[0014] Figure 2 This is a top view of the present invention.

[0015] In the diagram: 1. Oil pan; 2. Oil reservoir; 3. Oil return port; 4. Stepped surface; 5. C-shaped opening; 6. Oil guide plate; 7. Recessed hole. Detailed Implementation

[0016] 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.

[0017] In existing technologies, drones and small manned aircraft using inline 4-cylinder piston engines face challenges in engine size compatibility. Traditional oil pan designs return oil directly to the reservoir. During high-speed return, the oil violently impacts the reservoir wall due to inertia, causing splashing. This splashing not only increases the oil's contact area with air, accelerating oxidation, but also creates oil-air foam mixtures inside the oil pan, affecting the normal operation of the lubrication system.

[0018] To address these issues, researchers observed that the end shape of the oil return path directly affects fluid dynamics. Fluid dynamics simulations revealed that altering the geometry of the return port can effectively reduce fluid kinetic energy. Building on this, the research team attempted to incorporate multi-stage buffer structures within the oil return path and optimize the spatial relationship between the oil reservoir and the return port to eliminate the root cause of splashing.

[0019] Therefore, as Figures 1 to 2 As shown, this application proposes an oil return structure for an inline piston engine, including an oil pan 1. The oil pan 1 is configured as a basin-shaped structure with a horizontal inner bottom surface, and its inner bottom surface forms an outwardly protruding oil reservoir 2. An oil return port 3 with a C-shaped opening 5 is provided on the upper inner side of the oil pan 1. The upper end of the port is connected to an oil filter, and the lower end is connected to a stepped surface 4 that is higher than the oil reservoir 2. The C-shaped opening 5 forms a communication structure with the oil reservoir 2 through the stepped surface 4.

[0020] The oil storage tank 2 refers to the recessed area formed on the inner bottom surface of the oil pan 1 through a stamping process. Its convex structure increases the oil storage volume while reducing liquid level fluctuations. The C-shaped opening 5 refers to a tubular structure with an arc-shaped notch. The stepped surface 4 refers to the horizontal surface located above the oil storage tank 2.

[0021] Specifically, the oil pan 1 maintains a stable oil distribution through its horizontal inner bottom surface, while the recessed structure of the oil reservoir 2 reduces the overall height while ensuring sufficient oil storage capacity. When the engine oil flows down through the return port 3, it first contacts the stepped surface 4 to form a preliminary deceleration layer, and then flows into the oil reservoir 2 along the C-shaped opening 5. This multi-stage deceleration mechanism reduces the oil flow rate to below the critical value before it contacts the liquid in the oil reservoir 2, fundamentally preventing impact splashing.

[0022] Compared to existing technologies, traditional solutions directly insert the return oil pipe into the oil reservoir 2, causing the fluid to vertically impact the liquid surface. This solution, however, utilizes the synergistic effect of the stepped surface 4 and the C-shaped opening 5 to transform the vertical impact into a smooth flow. This change in flow path not only reduces fluid kinetic energy but also significantly improves the reliability of the lubrication system.

[0023] Through the above technical solution, this application effectively suppresses the splashing phenomenon during the oil return process, reduces oil oxidation loss and foam generation, and maintains the overall size of the engine through a compact structural design, making it particularly suitable for space-constrained UAV power systems.

[0024] This application further proposes that an oil guide plate 6 is vertically arranged on the stepped surface 4 inside the oil pan 1, which is higher than the oil storage tank 2, corresponding to the oil return interface 3.

[0025] The oil guide plate 6 refers to a vertical plate-like structure located in the area connecting the stepped surface 4 and the oil return interface 3. It can be implemented using metal sheet welding or integral injection molding, and is used to guide the flow direction of the engine oil. This structure constrains the engine oil to flow along a preset path through its vertically extending plate surface, preventing disorderly splashing.

[0026] Specifically, the oil guide plate 6 is installed vertically in the transition area between the stepped surface 4 and the oil reservoir 2. When engine oil flows in from the return port 3, the oil guide plate 6 vertically blocks the oil flow from directly impacting the surface of the oil reservoir 2, forcing the oil to flow along the channel formed by the oil guide plate 6. The flowing oil slides downwards under the action of gravity and eventually flows smoothly into the oil reservoir 2 in a laminar flow state. In this process, the oil guide plate 6 changes the original trajectory of the oil flow through physical obstruction, and at the same time reduces the flow kinetic energy through the guiding channel formed by the plate surface.

[0027] Compared to existing technologies, traditional oil pan 1 lacks any flow guiding structure, causing high-speed oil flow to directly impact the surface of the oil reservoir 2 during the return process, resulting in severe turbulence and oil droplet splashing. This solution introduces a vertical oil guide plate 6, transforming disordered impact into controlled stratified flow, eliminating the free collision process between the oil and the oil reservoir 2.

[0028] Through the above technical solution, this application effectively suppresses the liquid surface impact phenomenon during the oil return process and significantly reduces the amount of oil mist generated. The fluctuation range of the oil level inside the oil pan 1 is reduced, ensuring the oil pressure stability of the engine lubrication system. At the same time, splashed oil droplets adhere to the surface of the oil guide plate 6 and form an oil film, which can flow back to the oil reservoir 2 under gravity, avoiding unnecessary oil retention inside the housing.

[0029] This application further proposes that one end of the oil guide plate 6 is connected to the side of the oil return interface 3 near the oil storage tank 2 at the C-shaped opening 5.

[0030] The oil guide plate 6 refers to a plate-shaped component installed inside the oil pan 1 to guide the flow of engine oil. Its function is to change the flow path of the engine oil so that it enters the oil reservoir 2 smoothly. The C-shaped opening 5 refers to the semi-enclosed flow guiding structure formed at the end of the oil return port 3. Its function is to constrain the flow direction of the engine oil and reduce the flow velocity.

[0031] Specifically, when engine oil enters the oil pan 1 through the return port 3, the connection structure between the oil guide plate 6 and the edge of the C-shaped opening 5 forms a continuous guiding surface, forcing the engine oil to form an oil guiding channel between the surface of the oil guide plate 6 and the side wall of the oil pan 1. This oil guiding channel can cover the drop area between the side of the oil reservoir 2 and the stepped surface 4, allowing the engine oil to flow smoothly into the oil reservoir 2 below the liquid surface in a laminar flow state under the action of gravity, avoiding direct impact on the engine oil already stored in the oil reservoir 2. The overlap length between the oil guide plate 6 and the C-shaped opening 5 can be set to 1.2-3 times the opening width to ensure the smoothness of the flow direction change.

[0032] Compared to existing technologies, the traditional solution causes surface fluctuations when engine oil falls directly from the return port into the oil reservoir 2. This solution, however, utilizes the directional connection between the guide plate 6 and the C-shaped opening 5 to add flow constraint and kinetic energy dissipation during the oil's descent. Existing technologies lack this directional guidance structure, resulting in oil splashing to a height of 30%-50% of the reservoir 2's depth. This solution, by extending the flow path, reduces the oil's kinetic energy to below the critical splash velocity.

[0033] Through the above technical solution, this application effectively suppresses the liquid surface impact and splashing phenomenon generated during the oil return process, avoids the decrease in pumping efficiency caused by oil mist formation and liquid surface fluctuations, and ensures the stability of the oil storage volume in the oil reservoir 2 through directional flow guidance. This structure can maintain the oil pressure balance in the oil pan 1 under continuous engine operation conditions, and prevent the oil pump from sucking in cavitation due to violent liquid surface fluctuations.

[0034] This application further proposes a recessed hole 7 at the center hole where the stepped surface 4 inside the oil pan 1, which is higher than the oil storage tank 2, connects to the oil return interface 3.

[0035] The recessed hole 7 at the center refers to the formation of a localized recessed structure at the connection between the oil return interface 3 and the stepped surface 4. This can be achieved using an arc-shaped groove or a conical countersunk hole structure. This recessed area guides the oil to flow along a specific path, reducing fluid impact energy. The smooth transition between the recessed hole 7 and the stepped surface 4 means that the connection between the edge of the recessed area and the stepped surface 4 is free of sharp corners or abrupt changes. This can be achieved using rounded chamfers or a gradually curved surface. This design reduces the formation of eddies during oil flow.

[0036] Specifically, after a recessed hole 7 is provided at the connection position between the stepped surface 4 of the oil pan 1 and the oil return port 3, when engine oil enters the oil pan 1 from the engine crankcase assembly through the oil return port 3, the guiding structure formed by the recessed hole 7 allows the engine oil to flow smoothly into the oil reservoir 2 along the curved surface of the recessed area. The depth and radius of curvature of the recessed area can be adjusted according to the oil flow rate. For example, an arc-shaped recess with a depth of 5-8 mm can be used to allow the engine oil to naturally flow to the bottom of the oil reservoir 2 under the action of gravity, avoiding direct impact on the oil surface of the oil reservoir 2.

[0037] Compared with existing technologies, this solution forms a buffer guide structure by setting a recessed hole 7, which allows the kinetic energy of the oil to gradually decrease during the flow process. At the same time, the smooth transition design avoids abrupt changes in the flow path.

[0038] Through the above technical solution, this application effectively reduces the impact splashing phenomenon during the oil return process, reduces the generation of air bubbles in the oil pan 1, and improves the oil storage stability. The recessed guide structure can also guide the oil to quickly deposit to the bottom of the oil reservoir 2, preventing oil mist from spreading in the engine compartment, thereby improving the working efficiency of the lubrication system.

[0039] This application further proposes that the recessed hole 7 and the stepped surface 4 inside the oil pan 1, which is higher than the oil storage tank 2, have a smooth transition.

[0040] The recessed hole 7 refers to the recessed structure located at the connection between the stepped surface 4 and the oil return interface 3. It can be formed through stamping or casting processes and is used to guide the oil flow towards the oil reservoir 2 and reduce flow resistance. Its function is to prevent turbulence at the junction of the stepped surface 4 and the recessed hole 7, thereby reducing splashing. The smooth transition refers to the continuous extension of the curved or inclined surface at the connection between the recessed hole 7 and the stepped surface 4. Specifically, it can be achieved using an arc-shaped curved surface or an inclined surface with an angle less than 45 degrees. Its function is to eliminate abrupt changes in the oil flow path and maintain laminar flow through gentle curvature changes.

[0041] Specifically, when engine oil enters the oil pan 1 through the return port 3, the recessed structure of the recessed hole 7 can receive the initially high-velocity oil flow and guide it to the stepped surface 4 through a smoothly transitioned curved surface. Since the curved surface has no sharp edges or steps, the oil naturally slides down the curved surface to the oil reservoir 2 under gravity, avoiding abrupt changes in flow velocity caused by abrupt changes in cross-section. During this process, the continuity of the oil flow path is maintained, and the kinetic energy of the flow is gradually consumed, thereby suppressing splashing caused by the breaking of liquid surface tension.

[0042] Compared with existing technologies, this solution uses a smoothly transitioning curved surface design to ensure that the oil flow direction continues downward under the action of gravity, eliminating the interference of right-angle structures on the flow path and significantly reducing flow resistance and energy loss.

[0043] Through the above technical solution, this application effectively solves the problem of splashing caused by sudden changes in the flow path during the oil return process, reduces the possibility of oil mixing with air to generate bubbles, and improves the efficiency of oil returning to the oil reservoir 2, thus ensuring the stable operation of the engine lubrication system.

[0044] This embodiment also provides an engine equipped with any of the above-mentioned oil return structures, which is applied to an engine on an unmanned aerial vehicle.

[0045] The oil return structure refers to the oil return system described in this application, which is formed by the combination of an oil reservoir, an oil return interface, and guide components located in 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 integrated design of the internal space of the oil pan and the oil return interface, the overall height can be reduced to meet the installation requirements of the UAV.

[0046] In unmanned aerial vehicle (UAV) applications, this engine can adapt to the requirements of compact space layout, improving its adaptability to UAVs.

[0047] This embodiment also provides an aircraft equipped with any of the engines described above.

[0048] 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 an oil return system.

[0049] 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.

[0050] 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. An oil return 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). An oil return port (3) is provided on the upper inner side of the oil pan (1). The upper end of the oil return port (3) is connected to the oil return device and its engine oil return pipeline system in the crankcase assembly of the engine. The lower end of the oil return port (3) is connected to the stepped surface (4) inside the oil pan (1) that is higher than the oil reservoir (2). The oil return port (3) is designed with a C-shaped opening (5) in cross-section. The C-shaped opening (5) of the oil return port (3) is connected to the oil reservoir (2) through the stepped surface (4).

2. The oil return structure of an inline piston engine according to claim 1, characterized in that: An oil guide plate (6) is vertically installed inside the oil pan (1) on the stepped surface (4) that is higher than the oil storage tank (2) at the oil return interface (3).

3. The oil return structure of an inline piston engine according to claim 2, characterized in that: One end of the oil guide plate (6) is connected to the opening edge of the C-shaped opening (5) of the return oil interface (3) near the oil storage tank (2).

4. The oil return structure of an inline piston engine according to claim 1, characterized in that: The center hole at the connection point between the stepped surface (4) inside the oil pan (1) which is higher than the oil storage tank (2) and the return oil interface (3) is designed as a recessed hole (7).

5. The oil return structure of an inline piston engine according to claim 4, characterized in that: The recessed hole (7) and the stepped surface (4) inside the oil pan (1) that is higher than the oil storage tank (2) are smoothly transitioned.

6. An engine, characterized in that, It is equipped with an oil return structure according to any one of claims 1-5.

7. An aircraft, characterized in that, It is equipped with the engine as described in claim 6.

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