A drain bolt fixing 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 an oil drain bolt fixing 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 the basin -like structure, the inner bottom surface of oil pan is concave downward and forms and the further oil storage groove that projects outwardly to the structure relative to the outer bottom surface of oil pan, the bottom of oil storage groove is provided with the oil drain hole that passes through, the oil drain bolt is sealed in the oil drain hole and is provided, the outer bottom surface of oil storage groove is corresponded to the bolt head side surface department of oil drain bolt and is provided with the limit bulge, the limit bulge is provided with the tight through -hole to the bolt head direction of oil drain bolt, the bolt head of oil drain bolt is provided with the anti -looseness limit through -hole, the tight through -hole and anti -looseness limit through -hole are provided with the limit pin or anti -looseness safety steel wire and pass through, the utility model adds the oil drain bolt anti -looseness fixed fulcrum, avoided the oil drain bolt loose condition in the operation process of engine.

Description

Technical Field

[0001] This utility model relates to the field of engine oil pan technology, specifically to a drain bolt fixing 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. The drain plug used for oil maintenance employs a direct thread fastening method. During aircraft operation, high-frequency vibrations occur, requiring frequent maintenance to prevent loosening and leakage from the oil pan. This is especially problematic at high altitudes where engine vibration is more intense, making traditional drain plug structures prone to loosening due to prolonged vibration. This not only causes oil leakage, affecting engine lubrication, but can also lead to serious safety hazards. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a drain bolt fixing 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 drain bolt fixing structure for an inline piston engine, comprising an oil pan located 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 bottom of the oil reservoir having a through drain hole, a drain bolt being sealed in the drain hole, and the bolt head of the drain bolt being in tight contact with the outer bottom surface of the oil reservoir, a limiting protrusion being provided on the outer bottom surface of the oil reservoir corresponding to the side of the bolt head of the drain bolt, a set-in through hole being provided on the limiting protrusion facing the bolt head of the drain bolt, an anti-loosening limiting through hole being provided on the bolt head of the drain bolt, and a limiting pin or anti-loosening safety wire being provided through the set-in through hole and the anti-loosening limiting through hole.

[0005] In some embodiments, a C-shaped drain ring is provided at the bottom of the oil storage tank at the drain hole.

[0006] In some embodiments, the inner wall of the C-shaped drain ring is flush with the inner wall of the drain hole.

[0007] In some embodiments, the inner wall of the C-shaped drain ring and the inner wall of the drain hole are provided with fixing threads that match the drain bolt.

[0008] In some embodiments, the drain bolt head is either an external hexagonal head or an internal hexagonal head.

[0009] In some embodiments, each sidewall plane of the bolt head of the drain bolt is provided with a through-hole for preventing loosening.

[0010] To achieve the above objectives, this utility model also provides the following technical solution: an engine, which is equipped with any of the above-described drain bolt fixing structures.

[0011] To achieve the above objectives, the present invention also provides the following technical solution: an aircraft equipped with the aforementioned engine.

[0012] Compared with the prior art, the beneficial effects of this utility model are: by adding an anti-loosening fixing point to the oil pan, the oil drain bolt is prevented from loosening during engine operation, effectively solving the leakage problem caused by the loosening of the traditional oil drain bolt due to vibration. At the same time, the oil reservoir design is optimized to reduce waste oil residue, which has the advantages of improving maintenance safety and reliability.

[0013] 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

[0014] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 1 ;

[0015] Figure 2 This is a schematic diagram of the structure of the present invention. Figure 2 ;

[0016] Figure 3 This is a top view of the present invention;

[0017] Figure 4 This is a front view of the present invention.

[0018] In the diagram: 1. Oil pan; 2. Oil reservoir; 3. Drain hole; 4. Drain bolt; 5. Bolt head; 6. Limiting protrusion; 7. Set hole; 8. Anti-loosening limiting hole; 9. C-shaped drain ring. Detailed Implementation

[0019] 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.

[0020] In existing technologies, small manned aircraft and industrial drones generally use inline four-cylinder piston engines. However, these engines have the limitation of large size, affecting the adaptability of the aircraft. Traditional oil pan drain plugs use threaded fastening, which is prone to loosening under the high-frequency vibration environment of the aircraft, leading to the risk of oil leakage. This problem is particularly prominent in industrial scenarios that require long-term stable operation, requiring maintenance personnel to frequently check the tightness, increasing maintenance costs.

[0021] To address the aforementioned issues and the stability deficiencies of traditional threaded fasteners under high-frequency vibration, designers observed that bolt loosening stems from insufficient restriction of the rotational freedom. Analysis of the oil pan structure revealed that a single threaded connection is ill-suited to handling alternating loads. Based on the principle of mechanical anti-loosening, the feasibility of adding rigid restraints to the bolt's lateral side was explored, while ensuring ease of oil draining. Further research investigated the impact of the oil pan's oil reservoir morphology on oil drainage efficiency, proposing a synergistic effect by optimizing the reservoir shape and drain hole location in conjunction with the anti-loosening structure.

[0022] Therefore, as Figures 1 to 4 As shown, this application proposes a drain bolt fixing structure for an inline piston engine, including an oil pan 1. The oil pan 1 forms a basin-shaped structure with a horizontal inner bottom surface. The inner bottom surface is recessed to form an oil reservoir 2. An oil drain hole 3 is opened at the bottom of the oil reservoir 2 and a drain bolt 4 is sealed thereon. The bolt head 5 contacts the outer bottom surface of the oil reservoir 2. The outer bottom surface of the oil reservoir 2 is provided with a protrusion with a locking through hole 7. The bolt head 5 is provided with multiple anti-loosening limiting through holes 8. A limiting pin or anti-loosening safety wire is provided between the locking through hole 7 and the anti-loosening limiting through hole 8.

[0023] The oil reservoir 2 refers to a partially convex area formed by the recessed bottom surface of the oil pan 1. It can be formed through a stamping process, and its volume is larger than the surrounding area to centrally store sediment impurities. The outer bottom surface of the oil reservoir 2 further protrudes outward, forming the working space for installing the drain bolt 4. The drain hole 3 is located at the lowest point of the oil reservoir 2 to ensure complete oil drainage. The bolt head 5 of the drain bolt 4 contacts the outer bottom surface of the oil reservoir 2, and sealing is assisted by end-face friction. The protrusion refers to a locally raised columnar structure on the outer bottom surface of the oil reservoir 2. The locking through hole 7 is axially parallel to the sidewall of the bolt head 5 and is formed by drilling. The rotational freedom of the bolt head 5 is constrained by a limiting pin or an anti-loosening safety wire.

[0024] Specifically, the horizontal design of the inner bottom surface of the oil pan 1 ensures even distribution of engine oil, while the oil reservoir 2 is recessed downwards to form a sedimentation zone for impurities. The drain hole 3 is located at the center of the bottom of the oil reservoir 2; when the drain bolt 4 is installed, its threaded section forms a sealed connection with the inner wall of the drain hole 3. The end face of the bolt head 5 is completely flush with the outer bottom surface of the oil reservoir 2, achieving initial sealing through bolt preload. A raised structure is located on the side of the bolt head 5, forming a mechanical interlock after the insertion of a limiting pin or the penetration of the anti-loosening safety wire. When the engine is running, the limiting pin or anti-loosening safety wire withstands shear loads, preventing the bolt head 5 from rotating due to vibration.

[0025] Compared to existing technologies, traditional solutions rely solely on thread friction to prevent loosening. This solution uses a limiting pin or anti-loosening safety wire to engage with the through hole, forming a rigid constraint that effectively eliminates rotational degrees of freedom. The optimized structure of the oil reservoir 2 positions the drain hole 3 at its lowest point, preventing the accumulation of residual oil. The raised structure integrates the locking through hole 7, eliminating the need for additional positioning brackets and simplifying the assembly process.

[0026] Through the above technical solutions, this application solves the problem of loosening of the traditional drain bolt 4 under high-frequency vibration, ensuring the sealing reliability of the oil pan 1. The limiting pin or anti-loosening safety wire, in conjunction with the through hole, forms a double locking mechanism, reducing maintenance frequency. The optimized structure of the oil reservoir 2 improves oil drainage efficiency and reduces damage to the engine from residual impurities.

[0027] This application further proposes that a C-shaped oil drain ring 9 is provided at the bottom of the oil storage tank 2 at the oil drain hole 3, and the inner wall of the C-shaped oil drain ring 9 is flush with the inner wall of the oil drain hole 3.

[0028] The C-shaped oil drain ring 9 refers to the annular structure surrounding the oil drain hole 3, with a C-shaped opening in its cross-section. It can be achieved through stamping or machining, and is used to guide oil flow and form a sealing boundary. The flush surface setting means that the inner wall of the C-shaped oil drain ring 9 is on the same plane as the inner wall of the oil drain hole 3. This can be achieved by adjusting the installation position or machining precision, eliminating step gaps and forming a continuous sealing surface.

[0029] Specifically, the C-shaped drain ring 9 is designed to be flush with the inner wall of the drain hole 3, eliminating any height difference between them. When installing the drain bolt 4, the threaded portion of the bolt directly contacts the inner wall of the drain hole 3 and the inner wall of the C-shaped drain ring 9, forming a continuous and uniform contact surface. During engine operation, the oil flow path is confined within the flush hole wall area, preventing localized oil stagnation or uneven pressure caused by steps or gaps.

[0030] Compared to existing technologies, traditional oil drain holes 3 often have steps or misalignments between them and the sealing ring, resulting in incomplete sealing surfaces and making them prone to leakage under vibration. This solution improves sealing reliability by using flush surfaces to ensure continuous sealing contact.

[0031] Through the above technical solution, this application solves the problem of sealing failure caused by structural misalignment between the oil drain hole 3 and the sealing ring, effectively reducing the risk of oil leakage, while reducing the frequent maintenance operations required due to incomplete sealing surfaces. At the same time, during maintenance, the C-shaped oil drain ring 9 can completely drain the oil in the oil pan 1, avoiding the accumulation of residual oil.

[0032] This application further proposes that the inner wall of the C-shaped drain ring 9 and the inner wall of the drain hole 3 are provided with fixing threads that match the drain bolt 4.

[0033] The inner wall of the C-shaped drain ring 9 and the inner wall of the drain hole 3 refer to the inner surface of the annular structure surrounding the area of ​​the drain hole 3. Specifically, they can be machined to form an internal thread structure that meshes with the external thread of the drain bolt 4, providing axial tightening force. The fixing thread refers to the internal thread structure with the same size and pitch as the external thread of the drain bolt 4. Specifically, it can be achieved using standard thread specifications or customized thread parameters, used to enhance the axial locking effect of the drain bolt 4 through thread engagement.

[0034] Specifically, the inner wall of the C-shaped drain ring 9 and the inner wall of the drain hole 3 form a double fastening interface with the drain bolt 4 through threaded engagement. During the screwing-in process of the drain bolt 4, its external thread simultaneously contacts the internal thread of the C-shaped drain ring 9 and the internal thread of the drain hole 3. When the engine is running, the frictional force generated by the thread engagement can counteract the tendency of the bolt to loosen due to vibration, while the thread preload maintains the tightness of the sealing surface.

[0035] Compared with existing technologies, traditional drain bolts 4 rely on a single point of contact between the bolt head 5 and the outer bottom surface of the oil pan 1 to achieve fastening. However, this solution increases the contact area and locking force distribution between the drain bolt 4 and the oil pan 1 through thread engagement, forming a multi-point fixing structure, thereby significantly improving vibration resistance.

[0036] Through the above technical solution, this application effectively solves the problem of oil leakage caused by the easy loosening of the drain bolt 4 under high frequency vibration environment. Through the dual fixing mechanism of thread engagement and bolt head 5, the stability of the sealing interface under long-term vibration conditions is ensured, while simplifying the frequency of maintenance operations.

[0037] This application further proposes that the bolt head 5 of the drain bolt 4 adopts an external hexagonal bolt head 5 or an internal hexagonal bolt head 5, and each side wall plane of the bolt head 5 of the drain bolt 4 is provided with a through anti-loosening limiting hole 8.

[0038] The bolt head 5 refers to the head structure used to tighten the drain bolt 4. Specifically, it can be implemented using either an external hexagonal bolt head 5 or an internal hexagonal bolt head 5. This structure forms an operable torque surface through its planar sidewall. The anti-loosening limiting through-hole 8 refers to a hole structure that penetrates the plane of the bolt head 5's sidewall. Specifically, it can be implemented using a circular hole with a diameter slightly larger than the diameter of the limiting pin or the anti-loosening safety wire. This through-hole forms a positioning channel through which the limiting pin or the anti-loosening safety wire can pass in any sidewall plane.

[0039] Specifically, when the drain bolt 4 is installed in the drain hole 3 of the oil reservoir 2, each of the six symmetrical planes on the sidewall of the bolt head 5 is provided with an anti-loosening limiting through hole 8. During maintenance, if the angle of the bolt head 5 needs to be adjusted, the anti-loosening limiting through hole 8 on any sidewall plane can be aligned with the locking through hole 7 on the outer bottom surface of the oil reservoir 2, and then a limiting pin, through-hole, or anti-loosening safety wire can be inserted to achieve rigid fixation. Since each sidewall plane has a through hole, the installation position of the limiting pin or anti-loosening safety wire can be dynamically matched with the rotation angle of the bolt head 5, avoiding assembly inconvenience caused by the limited position of a single through hole.

[0040] Compared with existing technologies, this solution uses through holes on multiple planes to form a redundant positioning structure, which can effectively limit the bolt head 5 at any rotation angle, significantly reducing the accuracy requirements of the bolt head 5 angle for maintenance operations.

[0041] Through the above technical solution, this application effectively solves the technical problem of circumferential loosening of the drain bolt 4 under high vibration environment. The multi-plane anti-loosening limiting through hole 8 structure forms a full circumferential positioning capability, avoiding the limiting failure caused by slight rotation of the bolt head 5, and ensuring the long-term stability of the sealing performance of the oil pan 1.

[0042] This embodiment also provides an engine with any of the above-mentioned drain bolt fixing structures, which is applied to the engine of an unmanned aerial vehicle.

[0043] The drain bolt fixing structure refers to the oil draining structure located on the oil reservoir in the lower oil pan 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 a four-cylinder piston engine. Through an optimized drain bolt fixing structure design, the problem of drain bolt loosening due to vibration is reduced.

[0044] In unmanned aerial vehicle (UAV) applications, this engine can adapt to the requirements of compact space layout, improving its adaptability to UAVs.

[0045] This embodiment also provides an aircraft equipped with any of the engines described above.

[0046] 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 propulsion. The engine is an inline four-cylinder piston engine with an oil drain bolt fixing structure.

[0047] 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.

[0048] 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 drain plug (4) fixing 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 storage groove (2) that protrudes further outward relative to the outer bottom surface of the oil pan (1). A through oil drain hole (3) is provided at the bottom of the oil storage groove (2). An oil drain bolt (4) is sealed in the oil drain hole (3), and the bolt head (5) of the oil drain bolt (4) is tightly fitted to the outer bottom surface of the oil storage groove (2). In solid contact, the outer bottom surface of the oil reservoir (2) is provided with a limiting protrusion (6) corresponding to the side of the bolt head (5) of the oil drain bolt (4). The limiting protrusion (6) is provided with a tightening through hole (7) facing the bolt head (5) of the oil drain bolt (4). The bolt head (5) of the oil drain bolt (4) is provided with an anti-loosening limiting through hole (8). A limiting pin or anti-loosening safety wire is provided through the tightening through hole (7) and the anti-loosening limiting through hole (8).

2. The drain bolt (4) fixing structure for an inline piston engine according to claim 1, characterized in that: A C-shaped oil drain ring (9) is provided at the bottom of the oil storage tank (2) at the oil drain hole (3).

3. The drain bolt (4) fixing structure for an inline piston engine according to claim 2, characterized in that: The inner wall of the C-shaped drain ring (9) is flush with the inner wall of the drain hole (3).

4. The drain bolt (4) fixing structure for an inline piston engine according to claim 3, characterized in that: The inner wall of the C-shaped drain ring (9) and the inner wall of the drain hole (3) are provided with fixing threads that match the drain bolt (4).

5. The drain bolt (4) fixing structure for an inline piston engine according to claim 1, characterized in that: The head (5) of the drain bolt (4) is either an external hexagonal bolt head (5) or an internal hexagonal bolt head (5).

6. The drain bolt (4) fixing structure for an inline piston engine according to claim 5, characterized in that: Each sidewall plane of the bolt head (5) of the oil drain bolt (4) is provided with a through anti-loosening limiting hole (8).

7. An engine, characterized in that, It is equipped with an oil drain bolt fixing structure according to any one of claims 1-6.

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

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