Lubricating oil composition for two-stroke engine of unmanned aerial vehicle and preparation method

Abstract

The invention relates to the technical field of lubricating oil, in particular to a lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle, which comprises the following components in percentage by weight: 85%-92% of synthetic base oil, 2%-3.5% of antioxidant, 1.5%-2.5% of antiwear agent, 2%-4% of detergent dispersant, 1%-2% of viscosity index improver, 0.3%-0.8% of metal deactivator, 0.01%-0.02% of defoaming agent and 0.05%-1.00% of special fluorine surfactant. Wherein the special fluorine surfactant is a perfluoropolyether derivative, and the synthetic base oil contains ester compounds. By virtue of the synthetic base oil containing the ester compound, an ideal foundation platform with wide temperature range performance is established for the lubricating oil composition. The innovative synthetic base oil and the special fluorine surfactant have a synergistic effect, so that the performance of the oil product is fundamentally improved, the oil product has inherent wide-temperature-range stability, cavitation resistance and long-acting anti-oxidation cleanliness, and a fundamental guarantee is provided for the reliability and long service life of an unmanned aerial vehicle engine under extreme working conditions.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, specifically to a lubricating oil composition and preparation method for a two-stroke engine of an unmanned aerial vehicle. Background Technology

[0002] Two-stroke heavy oil engines have become the mainstream power source for industrial drones due to their significant advantages of high thrust-to-weight ratio and simple structure. However, their application scenarios are unique, such as ambient temperatures as low as -50°C and local temperatures within the combustion chamber exceeding 280°C. Under these extreme temperature conditions, lubricating oil is prone to viscosity changes, thermal decomposition, and lubricating film rupture, thereby reducing engine operating efficiency and service life.

[0003] Furthermore, the low-pressure environment at high altitudes can easily cause air bubbles to form in the lubricating oil, leading to insufficient oil supply pressure from the oil pump and thus increasing the risk of lubrication failure. At the same time, the lubricating oil must also possess an extremely long oxidation life and excellent cleaning properties to prevent the formation of carbon deposits and varnish during continuous operation for tens of hours.

[0004] Existing engine lubricating oil products, such as those described in CN201410589508.X and CN202111300046.1, cannot solve the aforementioned technical problems. These challenges place higher demands on the formulation design of lubricating oil compositions and prompt researchers to continuously explore more advanced additive systems and preparation processes to meet practical needs. Therefore, there is a need for a lubricating oil composition and its preparation method suitable for two-stroke engines of unmanned aerial vehicles (UAVs). This lubricating oil composition must meet the requirements of an extremely wide temperature range, low-pressure environment, and long flight time, thereby solving the aforementioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle (UAV) to solve the above-mentioned technical problems.

[0006] A lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle, wherein the components and their weight ratios of the lubricating oil composition are as follows: The composition includes 87%–90% synthetic base oil, 2%–3.5% antioxidant, 1.5%–2.5% anti-wear agent, 2.5%–4% detergent-dispersant, 2%–3% viscosity index improver, 0.3%–0.8% metal deactivator, 0.01%–0.02% defoamer, and 0.05%–0.08% special fluorinated surfactant; wherein the special fluorinated surfactant is a perfluoropolyether derivative, and the synthetic base oil contains ester compounds.

[0007] Furthermore, the bond energy of the fluorocarbon chain of the special fluorosurfactant is 450 kJ / mol to 485 kJ / mol.

[0008] Furthermore, the ester compound comprises diester and polyol ester, wherein the weight ratio of the diester to the polyol ester is (3:2) to (7:3).

[0009] Furthermore, the antioxidant comprises alkyl diphenylamine and high molecular weight shielding phenol, wherein the weight ratio of the alkyl diphenylamine to the high molecular weight shielding phenol is 1:1.

[0010] Furthermore, the synthetic base oil may also be a mixture comprising polyalphaolefin and alkylnaphthalene, wherein the weight ratio of the polyalphaolefin to the alkylnaphthalene is (7:3) to (7:2).

[0011] Furthermore, the anti-wear agent includes ashless phosphate or thiophosphate, and nano borate, wherein the weight ratio of the ashless phosphate or thiophosphate to the nano borate is (1:2):(2:3).

[0012] Furthermore, the cleaning and dispersing agent comprises high molecular weight succinimide and Mannich base, with a weight ratio of (2:1) to (3:1).

[0013] Furthermore, the viscosity index improver is polymethacrylate, the metal deactivator is a benzotriazole derivative, and the main component of the defoamer is polysiloxane.

[0014] A method for preparing a lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle (UAV) includes the following steps: After heating the synthetic base oil to a preset temperature, antioxidants, anti-wear agents, detergents and dispersants, viscosity index improvers, metal deactivators, defoamers, and special fluorinated surfactants are added sequentially. The mixture is then mixed and allowed to stand to obtain the lubricating oil composition with a pour point of -50 to -45°C and a thermal decomposition threshold of not less than 280°C.

[0015] Furthermore, the preset temperature is 55-65℃, the mixing is carried out under stirring conditions, the stirring speed is 55-65 r / min, and the standing time is 40-50 min.

[0016] Compared with the prior art, the beneficial effects of the present invention are: By utilizing synthetic base oils containing ester compounds, an ideal platform for wide-temperature-range performance is established for lubricant compositions. The synergistic effect of this innovative synthetic base oil and special fluorinated surfactants fundamentally optimizes oil performance, endowing the oil with inherent wide-temperature-range stability, anti-cavitation properties, long-lasting antioxidant cleaning properties, and excellent protection of lightweight alloys within the engine. This reduces the lubricant's reliance on external pressure compensation systems, providing a fundamental guarantee for the reliability and long lifespan of UAV engines under extreme operating conditions. Attached Figure Description

[0017] Figure 1 The lubricity index curve is an embodiment of this application; Figure 2 A picture showing the detergency of standard oil 1 in this application; Figure 3 Images showing the detergency of the test oil used in this application; Figure 4 Experimental data on exhaust smoke opacity for embodiments of this application; Figure 5 Experimental data for the exhaust blockage system of an embodiment of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] When drones are cruising at high altitudes, the ambient temperature can drop as low as -50°C, while the local temperature in the combustion chamber can exceed 280°C. Under such extreme temperature conditions, lubricating oils must possess both excellent low-temperature fluidity and high-temperature oxidation resistance.

[0020] Secondly, the low-pressure environment at high altitudes can easily cause traditional lubricating oil to generate bubbles, resulting in insufficient oil supply pressure from the oil pump and thus the risk of lubrication failure.

[0021] Third, lubricating oil needs to have an extremely long oxidation life and good cleaning properties to avoid the formation of carbon deposits and varnish during continuous operation for tens of hours, thus preventing engine performance degradation or malfunction.

[0022] To address the aforementioned problems, this application provides a lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle (UAV). The components and their weight ratios of the lubricating oil composition are as follows: The composition includes 87%–90% synthetic base oil, 2%–3.5% antioxidant, 1.5%–2.5% anti-wear agent, 2.5%–4% detergent-dispersant, 2%–3% viscosity index improver, 0.3%–0.8% metal deactivator, 0.01%–0.02% defoamer, and 0.05%–0.08% special fluorinated surfactants. Among these, the special fluorinated surfactants are perfluoropolyether derivatives, and the synthetic base oil contains ester compounds.

[0023] The most commonly used base oil in two-stroke synthetic lubricants is a mixture of polyols (such as pentaerythritol and trimethylolpropane) and fatty acids (such as isooctanoic acid and isodecanic acid) produced by esterification. This application replaces this with a synthetic base oil containing ester compounds, providing an ideal base platform for the lubricant composition with wide-temperature-range performance. Furthermore, a certain proportion of special fluorinated surfactants significantly enhances the wettability and spreadability of the lubricant composition on metal surfaces. Even in low-pressure environments, it can rapidly form a complete oil film, reducing dry friction under boundary lubrication conditions and further improving instantaneous start-up protection.

[0024] Synthetic base oils containing ester compounds work synergistically with special fluorinated surfactants, fundamentally improving oil performance. This results in enhanced key parameters such as lubricity index, initial torque index, detergency index, piston skirt varnish index, exhaust smoke index, and exhaust system blockage index, enabling the oil to withstand extreme internal and external temperature conditions. For example... Figure 1 As shown in this embodiment, comparative experimental data reveals that when the spark plug gasket temperature reaches 300°C, the lubricating oil composition of this application exhibits the smallest torque variation with temperature in the lubrication test. Compared to the other two oil products, the formulation of this application demonstrates a lower coefficient of friction and higher load-bearing capacity under the same operating conditions, further confirming its reliability in extreme environments.

[0025] This lubricant composition not only effectively reduces the wear rate of key engine components but also maintains relatively stable performance output even after prolonged operation, thereby extending the service life of the equipment. This characteristic is particularly suitable for the extremely demanding lubrication requirements of two-stroke engines in unmanned aerial vehicles (UAVs), providing strong support for their stable operation under complex conditions. Under extreme temperature conditions, the oil maintains stable viscosity, avoiding performance fluctuations caused by temperature changes. Simultaneously, its excellent detergency and dispersancy properties effectively inhibit the formation of carbon deposits and varnish, ensuring the cleanliness of internal engine components. (See details...) Figures 2-3 As shown. Furthermore, this lubricating oil composition exhibits excellent performance in reducing exhaust emissions, as detailed in [link to details]. Figure 4 and Figure 5 It meets modern environmental protection requirements and provides a reliable guarantee for the stable operation of drones in various complex environments.

[0026] Preferably, the fluorocarbon chain bond energy of the special fluorosurfactant is between 450 kJ / mol and 485 kJ / mol. Higher bond energy indicates a more stable chemical bond, requiring more energy to break. The fluorocarbon chain (CF) bond energy is significantly higher than the 413 kJ / mol of the CH bond in typical lubricating oil mixtures. This ensures that the lubricating oil composition neither decomposes nor volatilizes at high temperatures of 200–300°C, allowing it to replace additives in traditional mineral / synthetic oils (such as PAO and esters) and maintain the stability of the lubricating film. Simultaneously, the high bond energy of the fluorocarbon chain endows the lubricating oil composition with excellent chemical inertness, exhibiting excellent resistance to strong acids, strong alkalis, or oxidants. This characteristic not only extends the service life of the lubricating oil but also significantly improves its reliability under extreme operating conditions. Furthermore, the molecular structure design of the special fluorosurfactant enables it to form a directional adsorption layer on metal surfaces, further enhancing the shear resistance of the lubricating film. This property is crucial for the stability of two-stroke engines in unmanned aerial vehicles under high-frequency operating conditions.

[0027] Preferably, the ester compound contains diesters and polyol esters, with a weight ratio of diesters to polyol esters of (3:2) to (7:3). This composite system combines the excellent low-temperature fluidity of diesters with the superior high-temperature stability and oxidation life of polyol esters, forming an ideal platform for achieving wide-temperature-range performance. In use, the performance of the lubricating oil under different temperature conditions can be further optimized by adjusting the ratio of diesters to polyol esters. For example, in low-temperature environments, a higher proportion of diesters can significantly lower the pour point of the oil, ensuring good fluidity even in cold climates; while in high-temperature conditions, appropriately increasing the proportion of polyol esters helps improve thermal stability and oxidation resistance, thereby delaying oil aging. Furthermore, this composite system exhibits excellent solubility and is compatible with various functional additives, providing a reliable foundation for improving the overall performance of the lubricating oil composition.

[0028] Preferably, the synthetic base oil can also be a mixture containing polyalphaolefin and alkylnaphthalene, with a weight ratio of polyalphaolefin to alkylnaphthalene of (7:3) to (7:2). As an alternative to base oils containing ester compounds, replacing the synthetic base oil with a mixed system of polyalphaolefin and alkylnaphthalene can fully utilize the low volatility of polyalphaolefin and the excellent thermal stability of alkylnaphthalene, thereby providing more durable lubrication protection under high-temperature conditions. Simultaneously, the polar properties of alkylnaphthalene give it a stronger adsorption capacity to metal surfaces, further enhancing the anti-wear performance of the lubricating oil composition. Furthermore, this formulation range has been rigorously selected, ensuring the overall performance of the oil while effectively reducing production costs and improving the product's market competitiveness.

[0029] This preferred solution is particularly suitable for two-stroke engines in unmanned aerial vehicles (UAVs) requiring long-term continuous operation, providing reliable lubrication. Extensive testing has shown that the synergistic effect of synthetic base oils containing polyalphaolefins and alkylnaphthalenes with special fluorinated surfactants can significantly improve the overall performance of the lubricant composition. The introduction of special fluorinated surfactants not only enhances the oil's anti-wear and load-carrying capacity but also improves its lubrication performance under extreme conditions. This synergistic effect results in stronger stability and longer service life of the lubricant under high temperature and high pressure environments. Simultaneously, the unique chemical structure of fluorinated surfactants helps form a denser protective film, effectively reducing direct contact between friction pairs and lowering wear rates. Furthermore, this combination optimizes the cleaning properties of the lubricant, preventing the formation of carbon deposits and sludge, ensuring the long-term efficient operation of internal engine components. This characteristic is especially suitable for the high requirements of the lubrication system in two-stroke engines for UAVs, providing more reliable protection under complex operating conditions.

[0030] Preferably, the anti-wear agent includes ashless phosphate ester or thiophosphate ester and nano-boronate, with a mass ratio of ashless phosphate ester or thiophosphate ester to nano-boronate ester of (1:2):(2:3). For example, a mixture of phosphate ester and nano-boronate ester can be used, or a mixture of thiophosphate ester (such as tricresyl phosphate) and nano-boronate ester can be used. Through the technical modification of nano-boronate ester, a robust and self-healing protective film can be formed on the surface of the friction pair, significantly reducing wear, especially under high temperature and high load conditions. The formation of this protective film depends not only on the unique properties of nano-boronate ester but also on its dispersion stability in lubricating oil. By precisely controlling the ratio of ashless phosphate ester or thiophosphate ester and nano-boronate ester, the thickness and uniformity of the protective film can be further optimized, thereby improving its adaptability under complex working conditions. In addition, this combination of anti-wear agents can also work synergistically with other additives to enhance the overall performance of lubricating oil, especially in reducing dry friction at engine start-up. Experimental results show that the lubricating oil with this optimized ratio significantly reduces the surface roughness of the friction pairs after prolonged operation, indicating its excellent anti-wear and repair capabilities. This characteristic provides more comprehensive protection for the two-stroke engine of the UAV under conditions of frequent start-stop and high-load operation.

[0031] Preferably, the detergency dispersant comprises high molecular weight succinimide and Mannich base, with a weight ratio of (2:1) to (3:1). For example... Figure 3As shown, this complex effectively inhibits the formation of varnish and sludge, keeps the engine interior clean, and ensures that any generated microparticles are uniformly dispersed in the oil. This combination of detergents and dispersants also provides continuous cleaning during engine operation. High molecular weight succinimide is known for its excellent dispersing properties, effectively preventing particle aggregation, while Mannich base enhances cleaning power through its unique chemical structure, especially under high-temperature conditions. The synergistic effect of the two not only improves the overall performance of the lubricating oil but also extends its service life, thereby reducing maintenance frequency and costs. This balanced formulation design allows the detergents and dispersants to perform excellently under various operating conditions, meeting the stringent requirements of efficient lubrication and cleaning for two-stroke engines in unmanned aerial vehicles.

[0032] Preferably, the viscosity index improver is polymethyl methacrylate (PMA). Compared to polyisobutylene (PIB) used in conventional lubricating oil mixtures, PMA ensures stable oil viscosity at different temperatures, reducing the effects of high-temperature thinning and low-temperature thickening. The molecular structure of PMA gives it excellent shear stability, maintaining the viscosity characteristics of the lubricating oil even under prolonged high-load operation. This property is particularly important for two-stroke engines in unmanned aerial vehicles (UAVs), as they often face severe temperature fluctuations and mechanical shear forces during operation. Furthermore, PMA effectively improves the low-temperature fluidity of the lubricating oil, ensuring rapid engine start-up and adequate lubrication in cold environments. This characteristic not only improves engine efficiency but also significantly reduces the risk of wear due to insufficient lubrication, thereby further extending engine life.

[0033] Preferably, the metal deactivator is a benzotriazole derivative, and the main component of the defoamer is polysiloxane. Using a benzotriazole derivative metal deactivator effectively inhibits the corrosion of copper, lead, and other metal parts by the lubricating oil. Simultaneously, as the main component of the defoamer, polysiloxane can quickly eliminate foam generated by the lubricating oil during high-speed operation, thus avoiding lubrication failure caused by bubbles. This combination not only improves the overall performance of the lubricating oil but also ensures stable engine operation under complex conditions. Furthermore, by precisely controlling the proportions of each component, the oxidation resistance and thermal stability of the lubricating oil can be further optimized, making it more suitable for long-term, high-load working environments. These characteristics work together to provide more reliable protection for the two-stroke engine of unmanned aerial vehicles (UAVs) while also meeting the stringent requirements of modern high-performance equipment for lubricating oil.

[0034] It is important to note that the amount of defoamer added must be strictly controlled to prevent foaming of the lubricating oil during circulation, which would affect its lubrication performance. In practice, it is generally recommended to determine the optimal addition ratio through small-scale trials. Furthermore, to ensure the stable performance of the lubricating oil, a constant temperature and stirring speed should be maintained during mixing. This not only helps to ensure the uniform distribution of each component but also effectively avoids performance deviations caused by excessively high local concentrations. Simultaneously, environmental conditions must be carefully controlled during storage and transportation to prevent external factors from adversely affecting the quality of the lubricating oil.

[0035] The method for preparing the lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle as described above includes the following steps: After heating the synthetic base oil to a preset temperature, antioxidants, anti-wear agents, detergents and dispersants, viscosity index improvers, metal deactivators, defoamers, and special fluorinated surfactants are added sequentially. The mixtures are then mixed and allowed to stand to obtain a lubricating oil composition with a pour point of -50 to -45°C and a thermal decomposition threshold of not less than 280°C. The synthetic base oil can be either a compound containing esters or a compound containing polyalphaolefins and alkylnaphthalenes, allowing users to flexibly formulate the composition according to their specific needs.

[0036] When selecting synthetic base oils, their compatibility with various additives should be fully considered to ensure optimal performance of the final lubricant composition. Furthermore, different operating environments and conditions may impose specific requirements on the type of base oil; therefore, a reasonable selection must be made based on specific circumstances in practical applications. By precisely controlling the proportions and addition order of each component, the overall performance of the lubricant can be further improved to meet the special requirements of two-stroke engines for unmanned aerial vehicles (UAVs). In the embodiments of this application, compounds containing esters were selected, and the final composition had a pour point below -42°C and a thermal decomposition threshold of not less than 280°C.

[0037] Preferably, the preset temperature is 55-65℃, the mixing is carried out under stirring conditions, the stirring speed is 55-65 r / min, and the standing time is 40-50 min. Example:

[0038] The lubricating oil composition of the present invention is prepared according to the following weight ratio: Synthetic base oil: 87% (of which, diesters account for 55% and polyol esters account for 32%) Antioxidant: 2.5% (alkyl diphenylamine to shielding phenol by weight ratio of 1:1) Anti-wear agent: 2.0% (of which, nano borate ester is 1.2% and ashless phosphate ester is 0.8%) Detergent and dispersant: 3.5% (of which, high molecular weight succinimide is 2.4% and Mannich base is 1.1%) Viscosity index improver: 2.5% (polymethyl methacrylate) Metal deactivator: 0.5% Defoamer: 0.01% Specialty fluorinated surfactant: 0.06% After heating the above-mentioned synthetic base oil to 60°C, antioxidants, anti-wear agents, detergents and dispersants, viscosity index improvers, metal deactivators, defoamers, and special fluorinated surfactants are added sequentially. The mixture is then slowly stirred in a mixing tank until completely dissolved and uniformly mixed. Following the above preparation method, the UAV-specific two-stroke lubricating oil composition of this invention is obtained. It should be noted that the special fluorinated surfactant should be added last, after all other components have been mixed, to achieve better results.

[0039] The lubricating oil composition samples prepared in the examples (hereinafter referred to as "test oil") and the lubricating oil compositions before improvement (hereinafter referred to as "standard oil 1" and "standard oil 2") were subjected to 500 hours of bench testing in cooperation with a major domestic UAV engine manufacturer. The composition of Standard Oil 1 and Standard Oil 2 used here is prior art (CN202111300046.1), and will not be described in detail here.

[0040] The tests mainly covered kinematic viscosity (100℃), flash point (closed cup), moisture, mechanical impurities, pour point, sulfate ash content, detergency index, piston skirt varnish index, lubricity index, initial torque index, exhaust smoke index, and exhaust system blockage index. The test results and experimental methods for each indicator of the technical solution in this application are shown in Table 1. The test results show that the lubricating oil composition of this application has a pour point below -42℃, and all other indicators meet the requirements.

[0041]

[0042] For lubricity index testing, such as Figure 1 As shown, when the engine spark plug gasket temperature reaches its maximum, the change in engine torque corresponding to the test oil is less than that corresponding to the standard oil. This indicates that the test oil provides superior lubrication performance under high-temperature conditions, effectively reducing internal engine friction losses. Further observation revealed that after prolonged operation, the torque fluctuation of the test oil was significantly smaller than that of the standard oil, demonstrating better stability. This characteristic helps improve engine efficiency and extend its service life. Furthermore, the test oil performed stably under different operating conditions, without significant performance degradation, proving its good adaptability and reliability.

[0043] Regarding the cleanliness index test, in the cleanliness images of various components (including cylinder head cavity, piston top, exhaust side, intake side, piston cavity, spark plug and piston ring), the internal carbon deposits of standard oil 1 were compared with those of the test oil. It was found that the engine components using the test oil had less wear, and there was less internal carbon deposits after disassembly and inspection, which fully met the lubrication requirements of UAVs for high-altitude long-endurance flight.

[0044] In the cleanliness index test, by Figure 2 and Figure 3 As can be seen from the comparison of the cleanliness images of various components (including the cylinder head cavity, piston top, exhaust side, intake side, piston cavity, spark plug, and piston rings), the engine using the test oil has less carbon buildup and less wear compared to standard oil 1. This demonstrates that the test oil fully meets the lubrication requirements of UAVs for high-altitude, long-endurance flight.

[0045] Further analysis revealed that, by Figure 2 and Figure 3 It is evident that the test oil exhibits superior cleaning performance under high-temperature conditions. The amount of carbon deposits in the cylinder head cavity and piston crown area is significantly lower than that of the standard oil, indicating that this lubricant effectively inhibits the formation of high-temperature oxidation products. Furthermore, the test oil's cleaning effect is equally outstanding in key areas on both the exhaust and intake sides, reducing the risk of engine performance degradation due to carbon buildup. Particularly noteworthy is the test oil's performance on crucial engine components such as spark plugs and piston rings, where almost no noticeable sludge or deposits were observed, thus ensuring long-term stable engine operation under complex conditions.

[0046] Regarding the exhaust smoke opacity test, the test results are as follows: Figure 4 As shown, the test oil performed excellently in the exhaust smoke test, with a smoke value significantly lower than that of standard oil 1 and standard oil 2. This indicates that the test oil can more fully reduce the generation of unburned particulate matter during combustion, thereby effectively suppressing exhaust pollution. Further analysis shows that its low smoke characteristic not only helps improve the engine's environmental performance but also improves fuel combustion efficiency, providing cleaner power support for UAVs' long-endurance high-altitude flights. At the same time, lower exhaust smoke also means that the lubricating oil provides more comprehensive protection for the engine's internal structure, reducing the risk of carbon buildup caused by incomplete combustion.

[0047] Regarding the exhaust system blockage test, the test results are as follows: Figure 5As shown, the test oil exhibited significant advantages, far surpassing standard oils 1 and 2 in preventing exhaust system blockage. Long-term operational testing revealed that the engine exhaust passage using the test oil maintained high patency, with no significant blockage observed. This not only helps maintain normal engine exhaust efficiency but also further improves the stability of overall power output. Furthermore, a clear exhaust system effectively reduces exhaust back pressure, thereby minimizing energy loss within the engine and providing more reliable power for UAVs during complex flight missions. Simultaneously, this characteristic also demonstrates the lubricant's excellent anti-oxidation and anti-deposit properties under high-temperature conditions, enabling it to maintain a clean exhaust system over a long period.

[0048] The test oil had the following performance indicators: Lubricity Index LIX = 105, Initial Torque Index TIX = 100, EGD Cleanliness Index DIX = 140, EGD Piston Skirt Coating Index VIX = 98, Exhaust Gas Index SIX = 100, and Exhaust Blockage Index BIX = 101. All six indicators met the technical specifications stipulated in the EGD grade standard, as detailed in Table 2.

[0049]

[0050] The above embodiments demonstrate that the present invention has successfully obtained a lubricating oil composition for a two-stroke engine of an unmanned aerial vehicle through the optimized design of specific components and proportions.

[0051] 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 lubricating oil composition for a drone two-stroke engine, characterized by, The composition of the lubricating oil composition and the weight ratio thereof are respectively: Synthetic base oil 87%-90%, antioxidant 2%-3.5%, anti-wear agent 1.5%-2.5%, cleaning dispersant 2.5%-4%, viscosity index improver 2%-3%, metal deactivator 0.3%-0.8%, defoaming agent 0.01%-0.02%, and special fluorine surfactant 0.05%-0.08%; The special fluorine surfactant is a perfluoropolyether derivative, and the synthetic base oil contains ester compounds.

2. The lubricating oil composition of claim 1, wherein: The bond energy of the fluorocarbon chain of the special fluorine surfactant is 450-485 kJ / mol.

3. The lubricating oil composition of claim 1 or 2, characterized in that: The ester compounds include diesters and polyol esters, and the weight ratio of the diesters to the polyol esters is (3:2)-(7:3).

4. The lubricating oil composition of claim 3, wherein: The antioxidant contains alkyl diphenylamine and high molecular weight shielding phenol, and the weight ratio of the alkyl diphenylamine to the high molecular weight shielding phenol is 1:

1.

5. The lubricating oil composition of claim 1 or 2, characterized in that: The synthetic base oil can also be a mixture containing poly-alpha-olefins and alkyl naphthalenes, and the weight ratio of the poly-alpha-olefins to the alkyl naphthalenes is (7:3)-(7:2).

6. The lubricating oil composition of claim 4, wherein: The anti-wear agent contains ashless phosphate ester or thiophosphate ester and nano borate ester, and the weight ratio of the ashless phosphate ester or thiophosphate ester to the nano borate ester is (1:2):(2:3).

7. The lubricating oil composition of claim 6, wherein: The cleaning dispersant includes high molecular weight succinimide and Mannich base, and the weight ratio of the two is (2:1)-(3:1).

8. The lubricating oil composition of claim 7, wherein: The viscosity index improver is polymethacrylate, the metal deactivator is benzotriazole derivative, and the main component of the defoaming agent is polysiloxane.

9. The method of preparing a lubricating oil composition for a two-stroke engine of unmanned aerial vehicles according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: After the synthetic base oil is heated to a preset temperature, the antioxidant, the anti-wear agent, the cleaning dispersant, the viscosity index improver, the metal deactivator, the defoaming agent, and the special fluorine surfactant are sequentially added, mixed, and left to stand, to obtain the lubricating oil composition with a pour point of-50 to-45℃ and a thermal decomposition threshold not lower than 280℃.

10. The method of claim 9, wherein, The preset temperature is 55-65℃, the mixing is performed under stirring, the stirring speed is 55-65 r / min, and the standing time is 40-50 min.

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