A redundant sealing structure for cylinder bores of a two-stroke engine for unmanned aerial vehicles

Abstract

This utility model discloses a redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles (UAVs). The cylinder head is fixedly mounted on the upper part of the cylinder body via a connector. A first groove is provided at the bottom of the cylinder head, recessing upwards from the bottom to form a downward-facing opening. Several annular grooves are provided on the wall of the first groove, with the diameter of the annular grooves being larger than the diameter of the wall of the first groove. These annular grooves recess outwards from the wall of the first groove, creating a notch at the position corresponding to the annular groove. The upper part of the cylinder body is embedded in the first groove, and the outer side wall of the upper part of the cylinder body contacts the side wall of the first groove. A gap is left between the top of the cylinder body and the bottom of the first groove, and a gasket is provided in this gap. An O-ring is provided within the annular groove, forming a redundant seal for the cylinder head and cylinder body. This application uses O-ring sealing to avoid seal failure due to assembly process fluctuations, significantly reducing the impact of human error on sealing performance.

Description

Technical Field

[0001] This utility model relates to the field of engine sealing technology, and in particular to a redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles. Background Technology

[0002] The engine cylinder bore sealing system is a core component ensuring the efficient and stable operation of an internal combustion engine. This is especially true for two-stroke engines used in unmanned aerial vehicles (UAVs), where their sealing performance directly affects power output reliability, fuel economy, and flight safety. In traditional engine structures, such as... Figure 1 and 2 As shown, cylinder bore sealing mainly relies on the combined structure of cylinder head, cylinder block and cylinder gasket. By applying preload through circumferentially distributed bolts, the cylinder gasket undergoes plastic or elastic deformation, thereby filling the microscopic gaps at the joint surface of cylinder head and cylinder block and blocking the leakage path of high temperature and high pressure combustion gas.

[0003] In existing sealing solutions, the cylinder head gasket, as the core sealing element, typically employs a composite structure of a metal skeleton and elastic materials, such as asbestos, rubber, or expanded graphite wrapped around a thin low-carbon steel sheet. Its working principle involves using the surface pressure generated by bolt tightening to compact the gasket. When the engine is running, the internal combustion pressure pushes the cylinder head to slightly lift, and the gasket compensates for the dynamic gap at the mating surface through its own resilience, maintaining the sealing pressure. However, this structure has significant limitations under the special operating conditions of two-stroke engines in unmanned aerial vehicles (UAVs). Gas leakage is prone to occur at the engine cylinder head and cylinder block mating surface for several reasons: insufficient bolt preload or uneven bolt tightening force leads to uneven distribution of sealing pressure, which the gasket cannot compensate for, resulting in high-temperature gas leakage; excessive flatness of the cylinder block / cylinder head, where the gasket cannot compensate for gaps when the deformation reaches a certain size, causing high-temperature gas to erode the sealing layer; high-frequency alternating stress in the cylinder during prolonged engine operation and fluctuations in combustion pressure accelerate gasket fatigue cracking; and in some special operating conditions, a sudden increase in internal engine pressure causes shock waves that damage the gasket's micro-sealing structure.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Utility Model Content

[0005] The purpose of this invention is to propose a redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles (UAVs) to solve the technical problem of poor sealing effect caused by easy deformation of the cylinder head gasket in the prior art.

[0006] Therefore, this utility model proposes a redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles includes a cylinder head, a cylinder block, a gasket, and an O-ring.

[0009] The cylinder head is fixedly mounted on the upper part of the cylinder body via a connector;

[0010] The cylinder head has a first groove at the bottom, which is recessed upward from the bottom of the cylinder head to form a first groove with the opening facing downward; the groove wall of the first groove has a plurality of annular grooves, the diameter of the annular grooves is larger than the diameter of the groove wall of the first groove, and the annular grooves are recessed outward from the groove wall of the first groove, so that the groove wall of the first groove forms a notch corresponding to the position of the annular groove.

[0011] The upper part of the cylinder body is embedded in the first groove, and the outer side wall of the upper part of the cylinder body is in contact with the side wall of the first groove;

[0012] A gap is left between the top of the cylinder and the bottom of the first groove, and the gasket is provided in the gap;

[0013] The O-ring is provided in the annular groove to form a redundant seal between the cylinder head and the cylinder body.

[0014] Preferably, the number of annular grooves is 1 to 4, and each annular groove is evenly distributed along the circumferential direction of the groove wall of the first groove, with an O-ring corresponding to each annular groove.

[0015] Preferably, the number of annular grooves is two.

[0016] Preferably, the O-ring is made of fluororubber or silicone rubber, and the cross-sectional diameter of the O-ring is 1.1 to 1.3 times the depth of the annular groove.

[0017] Preferably, the diameter of the groove wall of the first groove is adapted to the diameter of the outer side wall of the upper part of the cylinder, and the fitting gap between the two is 0.02~0.05mm.

[0018] Preferably, the connecting component is a bolt, and the cylinder head and the cylinder body are provided with corresponding bolt holes. The bolt passes through the bolt holes to fix the cylinder head and the cylinder body, and 4 to 6 bolts are evenly distributed along the circumference of the cylinder head.

[0019] Preferably, the gasket is made of copper, and the thickness of the gasket is 0.3~0.8mm, and the outer diameter of the gasket is not less than the outer diameter of the top of the cylinder.

[0020] The beneficial effects of this utility model compared with the prior art include:

[0021] 1. The O-ring of this application achieves sealing through its own elastic deformation, which is not directly related to the bolt preload. When the bolt preload is insufficient or the tightening force is uneven, the O-ring can still maintain a tight fit between the cylinder body and the side wall of the first groove, avoiding sealing failure caused by fluctuations in the assembly process and significantly reducing the impact of human operation errors on sealing performance.

[0022] 2. For cylinder block / cylinder head flatness deformation > 0.05mm, traditional gaskets cannot compensate for the gap due to rigidity limitations. O-rings, on the other hand, achieve sealing through filling rate and can adapt to the gap changes between the groove wall and the outer wall of the cylinder block. Even when the flatness is out of tolerance, they can still fill the fit gap through elastic deformation, thus solving the strict dependence of rigid sealing components on the machining accuracy of parts.

[0023] 3. During long-term engine operation, the high-frequency alternating stress and combustion pressure fluctuations generated in the cylinder can easily lead to fatigue cracking of traditional gaskets. However, in this application, the O-ring is located in the annular groove on the side and does not directly bear the axial stress of the cylinder. Its sealing performance is not affected by the periodic deformation of the cylinder. At the same time, the O-ring and the gasket share the function, reducing the wear rate of a single component and significantly improving the durability of the sealing system.

[0024] 4. Under special operating conditions where the cylinder pressure rises sharply, the micro-sealing structure of traditional gaskets is easily damaged by shock waves. However, the side sealing method of the O-ring in this application can avoid axial pressure impact. Even if the cylinder head gasket fails, the O-ring can still maintain the cylinder bore seal, ensuring that the engine can still work normally under extreme operating conditions and providing key redundancy protection for the flight safety of UAVs. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the prior art cylinder head of this utility model.

[0026] Figure 2 This is a schematic diagram of the prior art of this utility model.

[0027] Figure 3 This is a schematic diagram of the cylinder head structure according to a specific embodiment of this utility model.

[0028] Figure 4 This is a first structural schematic diagram of a specific embodiment of the present utility model.

[0029] Figure 5 This is a second structural schematic diagram of a specific embodiment of the present utility model.

[0030] Explanation of reference numerals in the attached drawings: 1-Cylinder head; 11-First groove; 12-Annular groove; 2-Cylinder block; 3-Cylinder gasket; 4-O-ring; 5-Connector. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0032] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0033] A redundant cylinder bore sealing structure for a two-stroke engine of an unmanned aerial vehicle, such as Figures 3-5 As shown, it includes cylinder head 1, cylinder block 2, cylinder head gasket 3, and O-ring 4;

[0034] The cylinder head 1 is fixedly mounted on the upper part of the cylinder body 2 via a connector 5;

[0035] The cylinder head 1 has a first groove 11 at its bottom. The first groove 11 is recessed upward from the bottom of the cylinder head 1 to form a first groove 11 with its opening facing downward. The groove wall of the first groove 11 has a plurality of annular grooves 12. The diameter D of the annular grooves 12 is larger than the diameter d of the groove wall of the first groove 11. The annular grooves 12 are recessed outward from the groove wall of the first groove 11, so that the groove wall of the first groove 11 forms a notch corresponding to the position of the annular grooves 12.

[0036] The upper part of the cylinder body 2 is embedded in the first groove 11, and the outer side wall of the upper part of the cylinder body 2 is in contact with the side wall of the first groove 11.

[0037] There is a gap between the top of the cylinder body 2 and the bottom of the first groove 11. The cylinder gasket 3 is provided in the gap. It should be noted that since the first groove 11 is recessed from the bottom of the cylinder head 1 upwards, the bottom of the first groove 11 is the position of the top of the first groove 11.

[0038] The annular groove 12 is provided with the O-ring 4 to form a redundant seal for the cylinder head 1 and the cylinder body 2.

[0039] Traditional single cylinder head gaskets 3 rely heavily on the uniformity of bolt preload for sealing. In contrast, the O-ring 4 of this application achieves sealing through its own elastic deformation, which is not directly related to bolt preload. Even when bolt preload is insufficient or uneven, the O-ring 4 can still maintain a tight fit between the cylinder body 2 and the sidewall of the first groove 11, avoiding sealing failure due to assembly process fluctuations and significantly reducing the impact of human error on sealing performance. For cases where the flatness deformation of the cylinder body 2 / cylinder head 1 is >0.05mm, traditional cylinder head gaskets 3 cannot compensate for the gap due to rigidity limitations. However, the O-ring 4, by achieving sealing through its filling rate, can adapt to changes in the gap between the groove wall and the outer wall of the cylinder body 2. Even when flatness exceeds tolerance, it can still fill the gap through elastic deformation, solving the problem of the stringent dependence of rigid sealing components on the machining accuracy of parts. During prolonged engine operation, the high-frequency alternating stress and combustion pressure fluctuations generated in the cylinder can easily lead to fatigue cracking of traditional cylinder head gaskets 3. However, in this application, the O-ring 4 is located within the side annular groove 12 and does not directly bear the axial stress of the cylinder. Its sealing performance is unaffected by the periodic deformation of the cylinder block 2. Furthermore, the O-ring 4 and cylinder head gasket 3 share the functional load, reducing the wear rate of a single component and significantly improving the durability of the sealing system. Under special operating conditions of sudden increases in cylinder pressure, the micro-seal structure of traditional cylinder head gaskets 3 is easily damaged by shock waves. However, the side sealing method of the O-ring 4 in this application can avoid axial pressure impacts. Even if the cylinder head gasket 3 fails, the O-ring 4 can still maintain cylinder bore sealing, ensuring that the engine can still operate normally under extreme conditions and providing critical redundancy for UAV flight safety. The cylinder body 2 and cylinder head 1 adopt a clearance fit design similar to a shaft hole. Combined with the elastic sealing characteristics of the O-ring 4, the ease of assembly and disassembly is greatly improved while ensuring sealing reliability. Compared with traditional interference fit or complex sealing structure, this application can reduce assembly resistance and part wear, reduce maintenance difficulty, and meet the needs of UAV equipment for rapid maintenance.

[0040] In some examples of this embodiment, the number of annular grooves 12 is 1 to 4, and each annular groove 12 is evenly distributed circumferentially along the groove wall of the first groove 11. Each annular groove 12 corresponds to an O-ring 4. The redundancy sealing level can be flexibly adjusted according to the sealing requirements of the engine cylinder bore. When the number is small (e.g., 1), the structure can be simplified and assembly steps can be reduced, which is suitable for scenarios with relatively low sealing requirements. When the number is moderate (e.g., 2 to 4), multiple independent seals can be formed, which significantly improves the sealing redundancy. At the same time, the circumferentially evenly distributed layout can ensure that the O-ring 4 is subjected to balanced force, avoiding the problem of insufficient local sealing pressure, and taking into account both sealing reliability and structural flexibility.

[0041] In other examples of this embodiment, such as Figure 5As shown, there are two annular grooves 12. The design of two annular grooves 12 achieves an optimal balance between redundant sealing and structural rationality. The two O-rings 4 can form a double seal, meeting the core requirement of UAV engine for sealing reliability. Compared with a larger number of annular grooves 12, it can avoid the problem of excessively long cylinder head 1 caused by excessively deep embedding of cylinder block 2, reduce the risk of heat accumulation caused by excessively long heat dissipation path, and ensure that the heat generated by combustion can be quickly dissipated through cylinder block 2, avoiding engine performance being affected by overheating.

[0042] In some other examples of this embodiment, the O-ring 4 is made of fluororubber or silicone rubber, and the cross-sectional diameter of the O-ring 4 is 1.1 to 1.3 times the depth of the annular groove 12. Fluororubber and silicone rubber have excellent oil resistance, high temperature resistance, and aging resistance, which can adapt to the high temperature and oily environment around the engine cylinder bore, extending the service life of the O-ring 4. At the same time, the design of the cross-sectional diameter being larger than the depth of the annular groove 12 (1.1 to 1.3 times) ensures that the O-ring 4 undergoes appropriate compression deformation after assembly, which ensures a tight fit with the outer wall of the cylinder block 2 and the groove wall of the first groove 11 to achieve a reliable seal, while avoiding elastic fatigue caused by excessive compression, thus balancing sealing effect and durability.

[0043] In some other examples of this embodiment, the diameter d of the groove wall of the first groove 11 is adapted to the diameter of the outer side wall of the upper part of the cylinder body 2, and the fitting gap between the two is 0.02~0.05mm. This fitting gap design (0.02~0.05mm) can ensure the ease of assembly and disassembly of the cylinder body 2 and the cylinder head 1 (meeting the basic requirements of clearance fit), and can also reduce the waste of deformation space of the O-ring 4 by minimizing the gap. If the gap is too small, it will easily cause assembly jamming; if it is too large, the O-ring 4 will need to undergo greater deformation to fill the gap, which may accelerate the wear of the O-ring 4. This gap range allows the O-ring 4 to achieve sealing within a reasonable deformation range, while reducing the shaking between the cylinder body 2 and the cylinder head 1 and improving structural stability.

[0044] In some other examples of this embodiment, the connecting member 5 is a bolt. The cylinder head 1 and the cylinder body 2 have corresponding bolt holes. The bolts pass through the bolt holes to fix the cylinder head 1 and the cylinder body 2, and 4 to 6 bolts are evenly distributed along the circumference of the cylinder head 1. Bolted connections are simple in structure and easy to disassemble, adapting to the maintenance needs of UAV engines. The 4 to 6 evenly distributed bolts ensure balanced force on the cylinder head 1 and cylinder body 2, avoiding seal failure due to localized loosening. This number range provides sufficient preload to ensure the initial sealing effect of the cylinder head gasket 3 without complicating the assembly process or causing excessive deformation of the cylinder head 1 due to excessive bolts, thus balancing connection reliability and assembly efficiency.

[0045] In some other examples of this embodiment, the cylinder head gasket 3 is made of copper, and the thickness of the cylinder head gasket 3 is 0.3~0.8mm. The outer diameter of the cylinder head gasket 3 is not less than the outer diameter of the top of the cylinder body 2. Copper material has good thermal conductivity and ductility, which can adapt to the high temperature environment at the top of the cylinder body 2 and achieve initial sealing. The 0.3~0.8mm thickness design can reduce the assembly height while ensuring sealing compensation capability, avoiding excessive gap between the cylinder head 1 and the cylinder body 2 due to excessive thickness of the cylinder head gasket 3. The design that the outer diameter of the cylinder head gasket 3 is not less than the outer diameter of the top of the cylinder body 2 can ensure full coverage of the sealing surface at the top of the cylinder body 2, prevent gas leakage from edge gaps, and form a complementary seal with the O-ring 4.

[0046] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0047] Although exemplary embodiments of the present invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the present invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the present invention.

Claims

1. A redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles, characterized in that: This includes the cylinder head, cylinder block, gaskets, and O-rings; The cylinder head is fixedly mounted on the upper part of the cylinder body via a connector; The cylinder head has a first groove at the bottom, which is recessed upward from the bottom of the cylinder head to form a first groove with the opening facing downward; the groove wall of the first groove has a plurality of annular grooves, the diameter of the annular grooves is larger than the diameter of the groove wall of the first groove, and the annular grooves are recessed outward from the groove wall of the first groove, so that the groove wall of the first groove forms a notch corresponding to the position of the annular groove. The upper part of the cylinder body is embedded in the first groove, and the outer side wall of the upper part of the cylinder body is in contact with the side wall of the first groove; A gap is left between the top of the cylinder and the bottom of the first groove, and the gasket is provided in the gap; The O-ring is provided in the annular groove to form a redundant seal between the cylinder head and the cylinder body.

2. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The number of the annular grooves is 1 to 4, and each annular groove is evenly distributed along the circumference of the groove wall of the first groove. Each annular groove contains a corresponding O-ring.

3. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The number of annular grooves is two.

4. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The O-ring is made of fluororubber or silicone rubber, and the cross-sectional diameter of the O-ring is 1.1 to 1.3 times the depth of the annular groove.

5. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The diameter of the groove wall of the first groove is adapted to the diameter of the outer side wall of the upper part of the cylinder, and the fitting gap between the two is 0.02~0.05mm.

6. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The connecting component is a bolt. The cylinder head and the cylinder body are provided with corresponding bolt holes. The bolt passes through the bolt holes to fix the cylinder head and the cylinder body. There are 4 to 6 bolts evenly distributed along the circumference of the cylinder head.

7. The redundant sealing structure for the cylinder bore of a two-stroke engine for unmanned aerial vehicles according to claim 1, characterized in that: The gasket is made of copper and has a thickness of 0.3~0.8mm. The outer diameter of the gasket is not less than the outer diameter of the top of the cylinder.

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