Special lubricating oil for unmanned aerial vehicle multi-fuel ignition type two-stroke engine and preparation method thereof

Abstract

This invention provides a special lubricating oil for multi-fuel spark-ignition two-stroke engines used in unmanned aerial vehicles (UAVs) and its preparation method, belonging to the field of lubricating oil technology. The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs comprises, by weight percentage: base oil, 66-81 wt%; additives, 15-20 wt%; and diluent, 4-14 wt%. The base oil includes hydrocarbon-based oil, polyisobutylene, and synthetic esters, wherein the hydrocarbon-based oil is a mixture of 70-85 wt% Group III hydrogenated mineral oil and 15-30 wt% Group IV hydrocarbon synthetic oil. The additives include a composite detergent-dispersant, a composite anti-adhesion detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver, and a compounding agent, wherein the octane number improver is N-methylaniline. The diluent is aviation kerosene.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil technology, specifically relating to a special lubricating oil for multi-fuel spark-ignition two-stroke engines used in unmanned aerial vehicles and its preparation method. Background Technology

[0002] With the development of artificial intelligence, flight control, and new power technologies, drones have been widely used in production, daily life, and military fields. Currently, drone power systems exhibit a clear characteristic of scenario differentiation: pure electric power, due to its low energy density, is only suitable for short-range, light-load drones; while the power requirements of medium- and long-range, medium-load drones must rely on spark-ignition engines.

[0003] Among various spark-ignition engines, the spark-ignition two-stroke engine has become one of the core power sources for low-cost medium- and long-range unmanned aerial vehicles (UAVs) (such as the Shahid 136 UAV) due to its advantages of simple structure, low cost, high power output, and high reliability. However, the working process and lubrication method of this type of engine are fundamentally different from those of traditional spark-ignition four-stroke engines. Specifically, the special lubricating oil for spark-ignition two-stroke engines (hereinafter referred to as "lubricating oil") needs to be mixed with fuel in a specific ratio before being injected into the oil tank. When the engine is running, the oil-fuel mixture first enters the crankcase to lubricate moving components such as the crankshaft-connecting rod mechanism. Then, under the action of the injector or carburetor, it is converted into a gaseous state and mixed with air before entering the cylinder through the air exchange port. After completing the cycle of compression, ignition, combustion, and power, the exhaust gas produced by the combustion of the mixture is discharged from the cylinder in the later part of the second stroke.

[0004] The aforementioned special operating conditions place dual stringent requirements on lubricating oil: on the one hand, lubricating oil needs to be completely burned in the cylinder along with the fuel, but the heavy organic components it contains have poor combustion characteristics, so the requirements for its combustion cleanliness (inhibiting carbon deposits and sludge formation) are extremely high; on the other hand, lubricating oil is diluted by dozens of times by the fuel during the actual lubrication process, which means that when it lubricates the internal friction pairs of the engine, it needs to have stronger anti-dilution ability and lubrication stability to avoid wear problems caused by insufficient oil film strength. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a special lubricating oil for multi-fuel spark-ignition two-stroke engines used in unmanned aerial vehicles (UAVs) and its preparation method, aiming to at least partially solve the above-mentioned technical problems. The specific technical solution provided by this invention is as follows.

[0006] As a first aspect of the present invention, a special lubricating oil for multi-fuel spark-ignition two-stroke engines for unmanned aerial vehicles is provided, comprising the following components by weight percentage: base oil, 66-81 wt%; additives, 15-20 wt%; and diluent, 4-14 wt%. The base oil comprises hydrocarbon-based oil, polyisobutylene, and synthetic esters, wherein the hydrocarbon-based oil is a mixture of 70-85 wt% Group III hydrogenated mineral oil and 15-30 wt% Group IV hydrocarbon synthetic oil; the additives comprise a composite detergent-dispersant, a composite anti-adhesion detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver, and a compounding agent, wherein the octane number improver is N-methylaniline; and the diluent is aviation kerosene.

[0007] As a second aspect of the present invention, a method for preparing a special lubricating oil for a multi-fuel spark-ignition two-stroke engine for unmanned aerial vehicles is provided, comprising: thoroughly mixing hydrocarbon-based oil, polyisobutylene and synthetic ester, then sequentially adding a composite detergent-dispersant, a composite anti-adhesion detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver and a compounding agent, stirring evenly and then adding a diluent, and mixing thoroughly to obtain a special lubricating oil for a multi-fuel spark-ignition two-stroke engine for unmanned aerial vehicles.

[0008] Based on the above technical solution, the special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs and its preparation method provided by the present invention have at least one of the following beneficial effects.

[0009] (1) In the embodiments of the present invention, the special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs (hereinafter referred to as lubricating oil) provided by the present invention, by selecting N-methylaniline as an octane number improver, can effectively increase the overall octane number of low-octane fuels such as kerosene and diesel, promote efficient combustion of the engine, thereby improving the engine's power performance, while reducing fuel consumption and improving fuel economy, meeting the power and range requirements of medium- and long-range UAVs. Adding N-methylaniline to the lubricating oil instead of adding it directly to the fuel can avoid N-methylaniline from contacting the engine fuel supply system for a long time, thereby inhibiting its corrosion of metal fuel tanks, fuel valves and other components, as well as its erosion of organic polymer components such as rubber fuel lines and plastic seals. It can also delay the formation of impurities such as gum in the fuel, and avoid impurities from damaging the fuel combustion performance. The base oil is mainly composed of a hydrocarbon-based oil made up of 70-85 wt% Group III hydrogenated mineral oil and 15-30 wt% Group IV hydrocarbon synthetic oil. Due to the high saturation of the two types of base oils, the activation effect of N-methylaniline on the unsaturated bond-related reactions in the hydrocarbon-based base oil can be weakened, reducing the oxidative deterioration of the base oil and ensuring the stability of the lubricating oil performance.

[0010] (2) In the embodiments of the present invention, the preparation method of special lubricating oil for multi-fuel spark-ignition two-stroke engine of UAV provided by the present invention first mixes hydrocarbon base oil, polyisobutylene and synthetic ester to build a stable basic system, then adds various additives in sequence to ensure uniform dispersion, and finally adds diluent to adjust the state of the system. The operation steps are reasonable and easy to control, which can ensure that the components are fully integrated and avoid the problem of uneven performance caused by improper mixing order. Finally, a special lubricating oil with stable performance that meets the requirements of multi-fuel spark-ignition two-stroke engine of UAV is obtained. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0012] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0013] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0014] In realizing this invention, it was discovered that, to simplify logistics and improve the fuel flexibility of UAVs, many UAVs currently use internal combustion engines that can flexibly switch between gasoline, aviation kerosene, and diesel. However, the octane rating of fuels such as kerosene and diesel is much lower than that of gasoline. Directly burning these low-octane fuels in UAVs leads to a decrease in in-cylinder combustion efficiency, significantly deteriorating the overall power and fuel economy of the aircraft. Aromatic amines are excellent octane improvers for hydrocarbon-based fuels, especially N-methylaniline, which has excellent octane-improving effects and is inexpensive. Adding aromatic amine additives to hydrocarbon-based fuels can significantly increase the overall octane rating of the fuel, thereby compensating for the adverse effects of decreased fuel octane rating on engine combustion and improving the range and payload of the UAV. However, if fuels with added aromatic amines are stored in the engine fuel supply system for a long time, they may corrode metal parts such as fuel tanks and fuel valves, and may also corrode and swell organic polymer parts such as rubber fuel lines and plastic seals. Furthermore, aromatic amines can promote the oxidation and polymerization of unsaturated bonds in hydrocarbon fuel molecules, leading to the generation of large amounts of impurities such as gum and peroxides in hydrocarbon fuels with added aromatic amines, which deteriorates fuel quality and shortens fuel storage life. Therefore, aromatic amines have not yet been widely used in the field of fuel additives.

[0015] Since lubricating oil is ultimately consumed by combustion along with fuel in the engine cylinder, aromatic amine additives can be added to the lubricating oil. The lubricating oil and fuel should be mixed before the drone takes off, and the remaining lubricating oil-fuel solution containing aromatic amine additives should be promptly drained after the drone's flight. This avoids the adverse consequences of directly adding aromatic amine additives to the fuel. However, adding aromatic amines to lubricating oil can impair its friction-reducing and anti-wear properties and reduce the propagation speed of the flame in the cylinder. Therefore, when adding aromatic amine additives to lubricating oil, it is also necessary to improve the lubricating oil's own friction-reducing and anti-wear properties and add suitable compounding agents to mitigate the adverse effects of aromatic amine additives on the relevant properties of the lubricating oil.

[0016] Based on this, the present invention provides a special lubricating oil for multi-fuel spark-ignition two-stroke engines for unmanned aerial vehicles (UAVs). The lubricating oil is composed of Group III hydrogenated mineral oil, Group IV hydrocarbon synthetic oil, polyisobutylene, and synthetic ester as base oil, and compounding agents, including composite detergent-dispersant, composite anti-sticking detergent, friction reducer-anti-wear agent, antioxidant, octane number improver, and compounding agent as additives. Aviation kerosene is used as diluent. It can effectively improve the combustion efficiency of low-octane fuels while ensuring the fuel flexibility of UAVs, avoid the storage defects of aromatic amine additives, and ensure the lubricating performance and combustion cleanliness of the lubricating oil when diluted with fuel through the synergistic effect of the components.

[0017] As a first aspect of the present invention, a special lubricating oil for multi-fuel spark-ignition two-stroke engines for unmanned aerial vehicles is provided, comprising the following components by weight percentage: base oil, 66-81 wt%; additives, 15-20 wt%; and diluent, 4-14 wt%. The base oil comprises hydrocarbon-based oil, polyisobutylene, and synthetic esters, wherein the hydrocarbon-based oil is a mixture of 70-85 wt% Group III hydrogenated mineral oil and 15-30 wt% Group IV hydrocarbon synthetic oil; the additives comprise a composite detergent-dispersant, a composite anti-adhesion detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver, and a compounding agent, wherein the octane number improver is N-methylaniline; and the diluent is aviation kerosene.

[0018] In this embodiment of the invention, the combination of base oil and additives ensures that the UAV can flexibly switch between fuels such as gasoline, aviation kerosene, and diesel, while effectively improving the combustion efficiency of low-octane fuels through octane number improvers, thereby improving engine power and economy. At the same time, it avoids the defects such as storage corrosion and impurity generation when aromatic amine additives are directly added to fuel. Moreover, under the synergistic effect of each component, even if the lubricating oil is diluted by fuel, it can still maintain excellent lubrication performance and combustion cleanliness, which is suitable for the special operating conditions of spark-ignition two-stroke engines for UAVs.

[0019] In some embodiments, the components in the base oil are expressed as follows by weight percentage: hydrocarbon oil, 35-68 wt%; polyisobutylene, 15-30 wt%; synthetic ester, 17-35 wt%.

[0020] In some specific embodiments, the average molecular weight of the polyisobutylene is 800-1000. The synthesized ester is trimethylolpropane trioleate.

[0021] Polyisobutylene, with an average molecular weight of 800-1000, can enhance the viscosity-temperature properties and shear stability of base oils, preventing oil film rupture at high engine speeds. Trimethylolpropane trioleate, as a synthetic ester, can improve the low-temperature fluidity and lubrication durability of base oils, making it suitable for the high-altitude, low-temperature start-up requirements of drones.

[0022] In some embodiments, the additives are comprised of the following components by weight percentage: composite detergent-dispersant, 20-50 wt%; composite anti-sticking detergent, 5-10 wt%; friction-reducing and anti-wear agent, 5-10 wt%; antioxidant, 2-5 wt%; octane number improver, 25-50 wt%; and compounding agent, 5-10 wt%.

[0023] In some specific embodiments, the composite detergent-dispersant is composed of 50-75 wt% polyisobutylene bis(succinimide) (e.g., additive T152 is optional) and 25-50 wt% succinimide (e.g., additive T161 is optional). The composite anti-sticking detergent is composed of 20-40 wt% calcium alkylphenolate sulfide (e.g., additive T151A is optional) and 60-80 wt% calcium petroleum sulfonate (e.g., additive T151B is optional). The friction-reducing and anti-wear agent is a modified borate ester (e.g., additive DX 622 is optional). The antioxidant is N-phenyl-α-naphthylamine (e.g., additive T531 is optional). The compounding agent is a polyetheramine with an average molecular weight of 2000-3000.

[0024] Among them, the composite detergent-dispersant, composed of polyisobutylene bis(succinimide) and succinimide, can effectively inhibit the formation of sludge and carbon deposits; the composite anti-ring-sticking detergent, composed of calcium alkylphenolate sulfonate and calcium petroleum sulfonate, can prevent piston ring sticking and ensure smooth engine operation. Modified borate esters, as friction-reducing and anti-wear agents, significantly improve the friction-wear performance of lubricating oil, overcoming the deteriorating effect of N-methylaniline on lubrication performance and meeting the lubrication requirements of high-intensity engines in high-altitude and low-temperature environments of UAVs. N-phenyl-α-naphthylamine can delay the oxidative deterioration of lubricating oil and extend its service life. Polyetheramine, as a compounding agent, can improve the combustion rate and flame stability of N-methylaniline-containing fuels in the cylinder, suppress its adverse effects on the combustion process, and ultimately achieve a precise match between the comprehensive performance of the lubricating oil and the engine operating conditions.

[0025] In some embodiments, the diluent is aviation kerosene, which can further optimize the viscosity of the lubricating oil, ensuring that it can still provide continuous and effective lubrication for the engine friction pairs in a diluted state after being mixed with fuel. At the same time, in conjunction with the saturation characteristics of hydrocarbon-based oil, it can jointly ensure the clean combustion of the lubricating oil and reduce the formation of carbon deposits.

[0026] As a second aspect of the present invention, a method for preparing a special lubricating oil for a multi-fuel spark-ignition two-stroke engine for unmanned aerial vehicles is provided, comprising: thoroughly mixing hydrocarbon-based oil, polyisobutylene and synthetic ester, then sequentially adding a composite detergent-dispersant, a composite anti-adhesion detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver and a compounding agent, stirring evenly and then adding a diluent, and mixing thoroughly to obtain a special lubricating oil for a multi-fuel spark-ignition two-stroke engine for unmanned aerial vehicles.

[0027] In this embodiment of the invention, the hydrocarbon-based oil, polyisobutylene, and synthetic ester are first thoroughly mixed to construct a stable base oil system, providing a good carrier for the subsequent dispersion of additives. Then, various additives are added sequentially and stirred evenly to avoid antagonistic reactions between different additives due to improper mixing order. This ensures that the functional components, such as the composite detergent-dispersant and friction-reducing / anti-wear agent, are uniformly dispersed and fully exert their synergistic effects. Finally, a diluent is added and mixed to precisely adjust the system viscosity to the suitable range. The overall process is simple and controllable, ensuring stable and uniform performance of the final product, fully meeting the stringent requirements of multi-fuel spark-ignition two-stroke engines for unmanned aerial vehicles (UAVs) for lubricating oil.

[0028] For example, the present invention provides a specific method for preparing a special lubricating oil for a multi-fuel spark-ignition two-stroke engine for unmanned aerial vehicles, including steps S1-S3.

[0029] Step S1: Add Group III hydrogenated mineral oil with a viscosity grade of 5, Group IV hydrocarbon synthetic oil with a viscosity grade of 10, polyisobutylene with an average molecular weight of 800-1000, and trimethylolpropane trioleate to a beaker in proportion. Stir and heat to 50-80℃, keep warm and wait for use to obtain the base oil.

[0030] Step S2: Weigh out T 152 additive, T 161 additive, T 115A additive, T 115B additive, DX 622 additive, T 531 additive, N-methylaniline and polyetheramine with a molecular weight of 2000-3000 according to the proportions, add them to the base oil under the condition of heat preservation, continue to stir at this temperature for 2-4 hours, then stop heating, and let it cool naturally to room temperature while stirring to obtain a mixed solution of additives and base oil.

[0031] Step S3: Add aviation kerosene to the above-mentioned mixture of additives and base oil in proportion, and stir at room temperature for 1-2 hours to obtain a special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs.

[0032] In some embodiments, when using the special lubricating oil for multi-fuel spark-ignition two-stroke engines for drones provided by the present invention, the lubricating oil is mixed with 20-50 times its volume of gasoline, aviation kerosene, or diesel to form a solution, which is then used as fuel for the multi-fuel spark-ignition two-stroke engine for drones, thereby achieving stable and efficient operation of the multi-fuel spark-ignition two-stroke engine for drones.

[0033] The present invention will be further illustrated below through embodiments and related test experiments. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0034] Example 1

[0035] The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs provided in this embodiment 1 is prepared using the following raw materials and specific methods.

[0036] (1) Add 224g of Class III hydrogenated mineral oil with a viscosity grade of 5, 56g of Class IV hydrocarbon synthetic oil with a viscosity grade of 10, 200g of polyisobutylene with an average molecular weight of 800-1000 and 200g of trimethylolpropane trioleate to a beaker, stir and heat to 60°C, keep warm and wait for use to obtain the base oil.

[0037] (2) Weigh out 60g of T 152 additive, 40g of T 161 additive, 6g of T 115A additive, 14g of T 115B additive, 10g of DX 622 additive, 10g of T 531 additive, 50g of N-methylaniline and 10g of polyetheramine with a molecular weight of 2000-3000 respectively, add them to the above-mentioned base oil at 60℃, keep at 60℃ and stir for 3h, then stop heating, and cool naturally to room temperature while stirring to obtain a mixed solution of additives and base oil.

[0038] (3) Add 120g of aviation kerosene to the mixture of the above additives and base oil, and stir at room temperature for 1.5h to obtain the special lubricating oil for multi-fuel spark-ignition two-stroke engines of UAVs.

[0039] Example 2

[0040] The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs provided in this embodiment 2 is prepared using the following raw materials and specific methods.

[0041] (1) Add 374g of Class III hydrogenated mineral oil with a viscosity grade of 5, 66g of Class IV hydrocarbon synthetic oil with a viscosity grade of 10, 120g of polyisobutylene with an average molecular weight of 800-1000 and 200g of trimethylolpropane trioleate to a beaker, stir and heat to 50°C, keep warm and wait for use to obtain the base oil.

[0042] (2) Weigh out 48g of T 152 additive, 48g of T 161 additive, 8g of T 115A additive, 12g of T 115B additive, 10g of DX 622 additive, 4g of T 531 additive, 60g of N-methylaniline and 10g of polyetheramine with a molecular weight of 2000-3000 respectively, add them to the above-mentioned base oil at 50℃, keep at 50℃ and stir for 4h, then stop heating, and cool naturally to room temperature while stirring to obtain a mixed solution of additives and base oil.

[0043] (3) Add 40g of aviation kerosene to the above mixture of additives and base oil, and stir the mixture of aviation kerosene, additives and high-boiling-point base oil components at room temperature for 2 hours to obtain special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs.

[0044] Example 3

[0045] The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs provided in this embodiment 3 uses the following raw materials and specific methods for preparation.

[0046] (1) Add 267.75g of Group III hydrogenated mineral oil with viscosity grade 5, 114.75g of Group IV hydrocarbon synthetic oil with viscosity grade 10, 212.5g of polyisobutylene with an average molecular weight of 800-1000 and 127.5g of trimethylolpropane trioleate to a beaker, stir and heat to 80°C, keep warm and wait for use to obtain the base oil.

[0047] (2) Weigh 22.5g of T 152 additive, 7.5g of T 161 additive, 1.5g of T 115A additive, 6g of T 115B additive, 15g of DX 622 additive, 7.5g of T 531 additive, 75g of N-methylaniline and 15g of polyetheramine with a molecular weight of 2000-3000 respectively, add them to the above-mentioned base oil at 80℃, keep at 80℃ and stir for 2 hours, then stop heating and let it cool naturally to room temperature while stirring to obtain a mixed solution of additives and base oil.

[0048] (3) Add 127.5g of aviation kerosene to the mixture of the above additives and base oil, and stir at room temperature for 1 hour to obtain a special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs.

[0049] Comparative Example 1

[0050] The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs provided in Comparative Example 1 is prepared using the following raw materials and specific methods.

[0051] (1) Add 240g of Class III hydrogenated mineral oil with a viscosity grade of 5, 70g of Class IV hydrocarbon synthetic oil with a viscosity grade of 10, 200g of polyisobutylene with an average molecular weight of 800-1000 and 230g of trimethylolpropane trioleate to a beaker, stir and heat to 60°C, keep warm and wait for use to obtain the base oil.

[0052] (2) Weigh out 60g of T 152 additive, 40g of T 161 additive, 6g of T 115A additive, 14g of T 115B additive, 10g of T 531 additive and 10g of polyetheramine with a molecular weight of 2000-3000 respectively, add them to the above-mentioned base oil at 60℃, maintain 60℃ and stir for 3h, then stop heating, and cool naturally to room temperature while stirring to obtain a mixed solution of additives and base oil.

[0053] (3) Add 120g of aviation kerosene to the mixture of the above additives and base oil, and stir at room temperature for 1.5h to obtain a special lubricating oil for UAV multi-fuel spark-ignition two-stroke engines that does not contain octane improvers and friction-reducing / wear-resistant agents.

[0054] Comparative Example 2

[0055] The special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs provided in Comparative Example 2 is prepared using the following raw materials and specific methods.

[0056] (1) Add 230g of Class III hydrogenated mineral oil with a viscosity grade of 5, 60g of Class IV hydrocarbon synthetic oil with a viscosity grade of 10, 200g of polyisobutylene with an average molecular weight of 800-1000 and 200g of trimethylolpropane trioleate to a beaker, stir and heat to 60°C, keep warm and wait for use to obtain the base oil.

[0057] (2) Weigh out 60g of T 152 additive, 40g of T 161 additive, 6g of T 115A additive, 14g of T 115B additive, 10g of T 531 additive, 50g of N-methylaniline and 10g of polyetheramine with a molecular weight of 2000-3000 respectively, add them to the base oil at 60℃, keep at 60℃ and stir for 3h, then stop heating and let it cool naturally to room temperature while stirring, thus obtaining a mixed solution of additives and base oil.

[0058] (3) Add 120g of aviation kerosene to the mixture of the above additives and base oil, and stir at room temperature for 1.5h to obtain a special lubricating oil for UAV multi-fuel spark-ignition two-stroke engines that does not contain friction-reducing and anti-wear agents.

[0059] Furthermore, the performance of the lubricating oils obtained in the above embodiments and comparative examples was tested according to the following test standards, and the test results are shown in Table 1.

[0060] The anti-wear performance of a special lubricating oil for a multi-fuel spark-ignition two-stroke engine used in unmanned aerial vehicles was evaluated using the four-ball method, as specified in SH / T 0189-2017. Test conditions: pressure 392 N, test time 60 min, testing machine speed 1200 r / min, test temperature 75 ± 2℃.

[0061] The load-carrying capacity of the special lubricating oil for multi-fuel spark-ignition two-stroke engines for UAVs was evaluated using the "GB / T 3142-2019 Determination of Lubricant Load-Carrying Capacity - Four-Ball Method".

[0062] The cleaning performance of air-cooled two-stroke gasoline engine oils was evaluated using the SH / T 0710-2001 "Evaluation Method for Cleanliness of Air-Cooled Two-Stroke Gasoline Engine Oils (EGD Method)". After the engine operated under given conditions, the rate of piston ring sticking and piston / cylinder head deposit formation caused by the lubricating oil was assessed. The cleaning performance of the tested lubricating oil was determined by comparing its cleaning performance score with that of a standard lubricating oil. Test conditions: engine speed 6000 r / min, throttle opening 100%, spark plug gasket temperature controlled at 260±2℃, CO volume concentration in engine exhaust 6.4±0.1%, test duration 3 hours.

[0063] The lubrication performance of the lubricating oil was evaluated using the standard SH / T 0668-1998, "Evaluation Method for Lubricity of Air-Cooled Two-Stroke Gasoline Engine Oils," after the engine operated under given conditions. Test conditions: engine speed 4000 r / min, throttle opening 100%, stable operation for 30 minutes, then cooling air turned off. The engine torque was measured as the spark plug gasket temperature rose from 200℃ to 300℃, and the torque drop was calculated as a set of data. Bench tests were conducted in the order of standard oil-test oil-standard oil, with each oil sample repeated at least five times and at most seven times. The lubricity of the tested lubricating oil was determined by comparing the average torque drop of the tested lubricating oil with that of the standard lubricating oil.

[0064] Table 1. Lubricating oil performance test results

[0065]

[0066] As shown in Table 1, regarding the wear scar diameter, the wear scar diameters of Examples 1-3 are 0.65 mm, 0.67 mm, and 0.66 mm, respectively, while the wear scar diameters of Comparative Examples 1-2 are 0.70 mm and 0.72 mm, respectively. The wear scar diameters of Examples 1-3 are significantly smaller than those of Comparative Examples 1-2, indicating that the lubricating oil of the present invention has superior anti-wear performance. At the maximum non-seizure load P... BIn the above tests, Examples 1-3 achieved 697 N, 697 N, and 726 N respectively, while Comparative Examples 1-2 all achieved 461 N. The maximum non-seize load of Examples 1-3 was significantly higher than that of Comparative Examples 1-2, demonstrating stronger load-bearing and wear-resistant capabilities. Regarding the detergency index, Examples 1-3 were 146, 143, and 145, while Comparative Examples 1-2 were 140 and 137 respectively. The higher detergency index of Examples 1-3 indicates superior performance in inhibiting carbon deposits and maintaining engine cleanliness. Regarding the lubricity index, Examples 1-3 were 105, 106, and 103, while Comparative Examples 1-2 were 98 and 100 respectively. The lubricity index of Examples 1-3 was also superior to that of Comparative Examples 1-2. In summary, the special lubricating oil for multi-fuel spark-ignition two-stroke engines of UAVs of the present invention is significantly superior to the comparative example in key performance aspects such as anti-wear performance, load-bearing capacity, detergency and lubricity, which fully demonstrates the rationality of its formulation design and the synergistic effect among its components.

[0067] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A special lubricating oil for multi-fuel spark-ignition two-stroke engines used in unmanned aerial vehicles, characterized in that, By weight percentage, it includes the following components: Base oil, 66-81 wt%; Additives, 15-20 wt%; Diluent, 4-14 wt%; The base oil includes hydrocarbon oil, polyisobutylene, and synthetic ester, wherein the hydrocarbon oil is composed of 70-85 wt% of Group III hydrogenated mineral oil and 15-30 wt% of Group IV hydrocarbon synthetic oil. The additives include a composite detergent-dispersant, a composite anti-sticking detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver, and a compounding agent, wherein the octane number improver is N-methylaniline; The diluent is aviation kerosene.

2. The lubricating oil according to claim 1, characterized in that, In the additive, the proportions of each component, by mass percentage, are as follows: Composite detergent and dispersant, 20-50wt; composite anti-sticking detergent, 5-10wt; friction reducer and anti-wear agent, 5-10wt; antioxidant, 2-5wt; octane number improver, 25-50wt; compounding agent, 5-10wt.

3. The lubricating oil according to claim 2, characterized in that, The composite cleaning and dispersing agent is composed of 50-75 wt% polyisobutylene bis(succinimide) and 25-50 wt% succinimide.

4. The lubricating oil according to claim 2, characterized in that, The composite anti-adhesion cleaning agent is composed of 20-40 wt% alkylphenol calcium sulfide and 60-80 wt% calcium petroleum sulfonate.

5. The lubricating oil according to claim 2, characterized in that, The friction-reducing and wear-resistant agent is a modified borate ester.

6. The lubricating oil according to claim 2, characterized in that, The antioxidant is N-phenyl-α-naphthylamine.

7. The lubricating oil according to claim 2, characterized in that, The compounding agent is a polyetheramine, and the average molecular weight of the polyetheramine is 2000-3000.

8. The lubricating oil according to claim 1, characterized in that, In the base oil, the proportions of each component, by mass percentage, are as follows: Hydrocarbon-based oil, 35-68 wt%; polyisobutylene, 15-30 wt%; synthetic ester, 17-35 wt%.

9. The lubricating oil according to claim 8, characterized in that, The average molecular weight of the polyisobutylene is 800-1000; The synthesized ester is trimethylolpropane trioleate.

10. A method for preparing a lubricating oil as described in any one of claims 1-9, characterized in that, include: The hydrocarbon-based oil, polyisobutylene, and synthetic ester are thoroughly mixed. Then, a composite detergent-dispersant, a composite anti-sticking detergent, a friction-reducing and anti-wear agent, an antioxidant, an octane number improver, and a compounding agent are added in sequence. After stirring evenly, a diluent is added and the mixture is thoroughly mixed to obtain a special lubricating oil for multi-fuel spark-ignition two-stroke engines used in UAVs.

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