阅读说明：本技术 一种铁路机车柴油机油抗氧分散剂组合物及其应用 (Antioxidant dispersant composition for diesel engine oil of railway locomotive and application thereof ) 是由 于军 万书晓 程亮 于 2021-01-26 设计创作，主要内容包括：本发明公开了一种铁路机车柴油机油抗氧分散剂组合物及其应用,属于铁路机车润滑油技术领域。该组合物包括以下按质量百分数计的组分：聚异丁烯基丁二酰亚胺76.84～80.00％、硫磷双辛伯烷基锌盐13.71～14.69％、辅助抗氧剂5.68～8.03％、噻二唑衍生物0.56～0.58％。将本发明的组合物或含有该组合物的复合剂应用于铁路机车柴油机油中,可以有效提高铁路机车柴油机油的内在质量,有效解决了铁路机车柴油机油应用过程中因黏度增长过快油品换油周期过短的问题。(The invention discloses an antioxidant dispersant composition for diesel engine oil of a railway locomotive and application thereof, belonging to the technical field of lubricating oil of the railway locomotive. The composition comprises the following components in percentage by mass: 76.84-80.00% of polyisobutenyl succinimide, 13.71-14.69% of zinc dithiophosphate dicapryl alkyl, 5.68-8.03% of auxiliary antioxidant and 0.56-0.58% of thiadiazole derivative. The composition or the complexing agent containing the composition is applied to the diesel engine oil of the railway locomotive, so that the inherent quality of the diesel engine oil of the railway locomotive can be effectively improved, and the problem of short oil change period caused by too fast viscosity increase in the application process of the diesel engine oil of the railway locomotive is effectively solved.)

1. An antioxidant dispersant composition for diesel engine oil of railway locomotives, which is characterized in that: the composite material comprises the following components in percentage by mass: 76.84-80.00% of polyisobutenyl succinimide, 13.71-14.69% of zinc dithiophosphate dicapryl alkyl, 5.68-8.03% of auxiliary antioxidant and 0.56-0.58% of thiadiazole derivative.

2. The railroad locomotive diesel engine oil antioxidant dispersant composition according to claim 1, characterized in that: the auxiliary antioxidant is a combination of any two or more of liquid high molecular weight phenolic ester type antioxidant, aminothioester, zinc diamyl dithiocarbamate and amine antioxidant.

3. The railroad locomotive diesel engine oil antioxidant dispersant composition according to claim 2, characterized in that: the polyisobutenyl succinimide is T154, and the zinc salt of sulfur, phosphorus and bis-octyl alkyl is T203; the liquid high molecular weight phenol antioxidant is IRGANOX L135, the amine antioxidant is dinonyl diphenylamine or liquid octyl butyl diphenylamine, and the thiadiazole derivative is T561.

4. The railway locomotive diesel engine oil complexing agent is characterized in that: the composite material comprises the following components in percentage by mass: the antioxidant dispersant composition of claim 1, wherein the antioxidant dispersant composition comprises 53.27-54.47%, the high-temperature detergent comprises 43.68-44.86%, and the pour point depressant comprises 1.85-1.87%.

5. The railroad locomotive diesel engine oil complex of claim 4, characterized in that: the high-temperature detergent is a mixture of low-alkali sulfonate, high-alkali sulfonate and sulfurized alkylphenol salt.

6. The railroad locomotive diesel engine oil complex of claim 4, characterized in that: the pour point depressant is selected from one or a mixture of poly-alpha-olefin and polymethacrylate.

Technical Field

The invention relates to the technical field of railway locomotives, in particular to an antioxidant dispersant composition for diesel engine oil of a railway locomotive and application thereof.

Background

The Locomotive oil has no international and unified specification standard at present, and for many years, the American Locomotive maintainer Association (Locomovive Locomotive Maintenance enterprises) and the General Electric Company (General Electric Company) integrate the continuously improved structural characteristics of a Locomotive diesel engine and the corresponding oil consumption requirements of the Locomotive oil, and provide a Locomotive oil LMOA classification method generally accepted by engine manufacturers. On the quality level, the LMOA divides the locomotive oil into first-generation oil, second-generation oil, third-generation oil, fourth-generation oil, fifth-generation oil and sixth-generation oil according to the total base number and the service performance; from the viscosity aspect, the locomotive oils are classified as SAE40, 15W/40, 20W/40 according to the classification method of SAE (the Society of Automobile Engineers) J300. According to the type of the additive, the locomotive oil can be divided into zinc-containing oil and non-zinc oil: the silver plating on the surfaces of a supercharger, a crank pin and a bearing bush of a locomotive produced by GM company must limit the zinc content in engine oil, so non-zinc oil is required to be used; locomotives without silver plated bearings may use a zinc-containing oil containing a zinc salt as an antioxidant.

For the selection of the oil for the railway internal combustion engine, special oil for the railway internal combustion engine must be used. The special oil for the railway locomotive puts special requirements on oil products, such as higher base number, excellent oxidation stability, sufficient detergent dispersibility and the like. Therefore, the railway diesel engine oil is not suitable for being mixed with the automobile diesel engine oil; the two major types of locomotive oils, i.e., zinc-containing oils and non-zinc oils, are also not suitable for long-term blending, otherwise they may cause a reduction in oil properties.

The diesel engine of the railway locomotive has a different use environment from the common diesel engine, and because the diesel engine is used in the field for a long time, the environment condition is poor, and more heavy fuels are increasingly used, the diesel engine oil has the requirements on the viscosity and the viscosity index of the diesel engine oil for the locomotive, and also has the performance requirements on wear resistance, corrosion resistance, high-temperature detergency, low-temperature dispersibility and the like. The problem that still using four or lower generation engine oils after a railroad locomotive is accelerated is often the frequent oil changes due to the faster increase in oil viscosity. According to the reasons that the original DF10, DF-4D, Dongfeng 8B and other types of locomotives in the Beijing internal combustion engine service section are shortened in oil change period, the reasons are that the soot content in engine oil is higher, the dispersibility of oil products is poorer, and the viscosity of the oil products is increased faster due to the oxidation of the oil products under severe conditions, so that the problems that: the surfaces of piston ring grooves, skirt sections, inner cavities and the like of the locomotive diesel engine are easy to be oxidized at high temperature, and meanwhile, the speed of generating paint films and carbon deposition on the surfaces of the pistons is accelerated by incomplete combustion products; the oxidation of the oil product is further intensified by the continuous oxidation of the locomotive oil in the crankcase to form various oxidation condensation products such as aldehyde, ketone, acid and the like, so that the viscosity of the oil product is increased. For this reason, antioxidant dispersant compositions are key components that affect engine oil quality.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide the antioxidant dispersant composition for the railway locomotive diesel engine oil, which can effectively improve the internal quality of the railway locomotive diesel engine oil and effectively solve the problem that the oil change period is too short because the viscosity is increased too fast in the application process of the railway locomotive diesel engine oil.

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 76.84-80.00% of polyisobutenyl succinimide, 13.71-14.69% of zinc dithiophosphate dicapryl alkyl, 5.68-8.03% of auxiliary antioxidant and 0.56-0.58% of thiadiazole derivative.

The core for controlling the excessive increase of the viscosity of the diesel engine oil of the railway locomotive is to ensure that the oil products do not generate insoluble substances and carbon deposition due to the rapid generation of oxides, so the ashless dispersant and the antioxidant are key components which have great influence on the quality of the diesel engine oil of the railway locomotive. According to the invention, the specific ashless dispersant and a plurality of specific antioxidants are compounded under a specific dosage, so that the composition disclosed by the invention can effectively solve the problem that the oil change period is too short because the viscosity is increased too fast in the application process of the railway locomotive diesel engine oil, and can effectively improve the internal quality of the railway locomotive diesel engine oil.

In a preferred embodiment of the present invention, the auxiliary antioxidant is a combination of two or more selected from the group consisting of a liquid high molecular weight phenolic ester type antioxidant, an aminothioester, zinc diamyldithiocarbamate, and an amine type antioxidant.

Specifically, the polyisobutenyl succinimide is T154, the zinc salt of sulfur-phosphorus-bis-octyl alkyl is T203, the liquid high-molecular-weight phenol antioxidant is IRGANOX L135, the amine antioxidant is dinonyl diphenylamine or liquid octyl butyl diphenylamine, the liquid octyl butyl diphenylamine is IRGANOX L57, and the thiadiazole derivative is T561.

The invention also provides a railway locomotive diesel engine oil complexing agent, which comprises the following components in percentage by mass: 53.27-54.47% of the antioxidant dispersant composition, 43.68-44.86% of high-temperature detergent and 1.85-1.87% of pour point depressant.

As a preferred embodiment of the invention, the high temperature detergent is a mixture of low alkali sulfonate, high alkali sulfonate, sulfurized alkylphenate.

In a preferred embodiment of the present invention, the pour point depressant is selected from polyalphaolefin, polymethacrylate, and a mixture of both.

Compared with the prior art, the invention has the beneficial effects that:

the invention screens ashless dispersant and antioxidant by a large number of tests to obtain antioxidant dispersion composition, and compounds the antioxidant dispersion composition with high-temperature detergent and pour point depressant to obtain complexing agent, and verifies the performances of oxidation corrosion, thermal stability, detergency, wear resistance and the like of the antioxidant dispersant composition or the complexing agent by the laboratory related simulation evaluation method (comprising a carbon black dispersion test method, an improved multi-metal oxidation test method and a paint/char formation simulation test method). In the railway locomotive service section running test of three test vehicles (oil prepared by using the composition) and three comparison vehicles (oil prepared by using the railway locomotive four-generation oil), the oil change is needed due to the fact that the viscosity of the engine oil is over standard when the engine oil in the individual comparison vehicles is used for only 1 ten thousand kilometers, and the average oil change period on the three test vehicles reaches about 6.6 ten thousand kilometers which is about 1.7 times of that of the comparison oil. Therefore, the composition shows better performance in the actual use process of the railway locomotive, so that the composition can effectively solve the problem that the oil change period is too short because the viscosity is increased too fast in the application process of the railway locomotive diesel engine oil, and can effectively improve the inherent quality of the railway locomotive diesel engine oil.

Drawings

FIG. 1 is a graph of operating mileage versus kinematic viscosity of engine oil for a test vehicle;

FIG. 2 is a graph comparing vehicle operating mileage to engine oil kinematic viscosity.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

The antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 76.84-80.00% of polyisobutenyl succinimide, 13.71-14.69% of zinc dithiophosphate dicapryl alkyl, 5.68-8.03% of auxiliary antioxidant and 0.56-0.58% of thiadiazole derivative.

Wherein the auxiliary antioxidant is a combination of any two or more of liquid high molecular weight phenolic ester type antioxidant, aminothioester, zinc diamyl dithiocarbamate and amine antioxidant. Specifically, the polyisobutenyl succinimide is T154, the zinc salt of sulfur-phosphorus-bis-octyl alkyl is T203, the liquid high-molecular-weight phenolic antioxidant is IRGANOX L135, the amine antioxidant is dinonyl diphenylamine or liquid octyl butyl diphenylamine (IRGANOX L57), the thiosemicarbazide is T323, the zinc diamyl dithiocarbamate is VANLUBE AZ, and the thiadiazole derivative is T561.

The dosage of the antioxidant dispersant composition in the engine oil is preferably 8.55-8.85%.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.27-54.47% of the antioxidant dispersant composition, 43.68-44.86% of high-temperature detergent and 1.85-1.87% of pour point depressant.

The dosage of the complexing agent in the engine oil is preferably 16.0-16.8%.

Screening test for one-ash-free dispersant

7.2% of each of polyisobutenyl succinimide (T154), high molecular weight polyisobutenyl succinimide (hitec646) and boronated polyisobutenyl succinimide (hitec648) was added as an ashless dispersant to a fixed system containing 7.4% of a detergent, 1.8% of an antioxidant and 83.6% of a base oil, and screening tests were conducted to examine the influence of different ashless dispersants on the dispersibility of a railway locomotive diesel engine oil.

The test method comprises the following steps: carbon black dispersion method simulation test method 1

Summary of test methods: dissolving 10% carbon black (aviation oil sludge) in the test oil, stirring for 5 minutes on a high-speed stirrer at 3000rpm, taking a drop of oil sample, placing in a constant-temperature pan at 120 ℃ for 15 minutes, measuring the diameter D of an oil ring and the diameter D of a carbon black ring, and calculating the ratio of D/D, namely the dispersion performance, wherein the results are shown in Table 1.

TABLE 1 comparison of Dispersion Performance of different ashless dispersants

Ashless dispersants	hitec646	hitec648	T154
				Dispersibility (D/D)	0.465	0.532	0.490

As can be seen from Table 1, the best dispersion performance was hitec648, the T154 times, and the worst dispersion performance of hitec 646. In order to reduce the production cost, T154 (polyisobutenyl succinimide) with intermediate dispersibility is selected as an ashless dispersant.

The experimental method comprises the following steps: carbon black dispersion method simulation test method 2

Summary of test methods: adding 3% of carbon black into the following test oils with different T154 adding amounts, wherein the adding amounts of other detergents and antioxidants in each group of test oils are the same, stirring for 10 minutes at 3000rpm, respectively detecting the viscosities of the new oil and the mixed carbon black oil, and calculating the viscosity increase value (%), wherein the results are shown in Table 2.

TABLE 2 viscosity increase of test oils at various T154 addition levels

T154 addition amount (%)	5.5	6.5	6.8	7.0	7.2
						Viscosity increase value (%)	8.33	9.67	10.35	11.20	4.5

Table 2 shows that the addition amount of T154 is not linearly related to the viscosity increase value of carbon black, the addition amount of the ashless dispersant is large, and the dispersibility is definitely good, but the addition amount of the ashless dispersant is too large, so that the addition amount of other additives is limited, and the performances such as wear resistance and oxidation resistance of oil products are influenced, therefore, the dosage range of T154 in the test oil is selected to be 6.8-7.2, namely the dosage range of T154 in the antioxidant dispersant composition is 76.84-84.2%.

Method for diesel engine oil oxidation experiment and crankcase simulation experiment of railway locomotive

The oxidation stability measuring method for SH/T0299 internal combustion engine oil is a laboratory simulation test method commonly used in the oil product development process. The method comprises the steps of suspending a test iron sheet, a test copper sheet and a test lead sheet in a test tube, oxidizing an oil product for 12 hours under the oxygen condition of 200ml/min +/-10 ml/min, and grading the mass change of the test metal sheet, the change of kinematic viscosity at 50 ℃, and the acid-base property of pentane insoluble substances and sample steam after oxidation. Because the test conditions of the method adopted in a laboratory are greatly different from the actual working conditions of the railway locomotive, the test conditions need to be adjusted according to the working conditions of the railway locomotive. The method for detecting the oxidation performance of the diesel engine oil of the railway locomotive, which is better related to actual running oil testing, is determined by changing the oxygen flow, adjusting the test time and optimizing the detection result.

The improved oxidation test and crankcase simulation test machine test are simulation test methods which are specially established by combining the actual working conditions of high engine thermal load and high strengthening coefficient of the railway locomotive, and the test methods have good effects when being applied to the research of the engine oil of the railway locomotive.

Specifically, the conditions of the modified oxidation test were: the oil temperature is 165 ℃, the oxygen introduction amount is 100ml/min, the test time is 12h/24h/26h, and the corrosion, viscosity and color comparison of the copper sheet and the lead sheet are tested after the test is finished, so that the comprehensive grading value is obtained.

The test conditions of the improved crankcase simulation tester are as follows: the oil temperature is 150 ℃, the plate temperature is 320 ℃, the test time is prolonged from 6h to 48h, the content of the test is changed from the original carbon deposit and paint film on the metal plate to the viscosity increase value and the base number decrease value of the test engine oil, so that the original crankcase simulation test machine is only used for cleaning test and is expanded to the test of thermal oxidation stability and oxidation stability of the engine oil.

Applicants added the antioxidant dispersant composition of the present invention to the oil in varying amounts and conducted the oxidation test and crankcase simulation test, respectively, under the conditions described above, with the results shown in table 3.

TABLE 3 Oxidation test and crankcase simulation test results for oils with different addition of antioxidant dispersant compositions

As can be seen from Table 3, the test time is adjusted from 12h to 24h, the improved oxidation test result has better distinguishability, but the trend of the improved oxidation test method is not very consistent with that of the improved crankcase simulation test machine, the oxidation process tested by the two methods is different, and the good oil quality is obtained by the two test methods; the significance of the decrease of the base number measured by the improved crankcase simulation testing machine is that the acid number of an oxidized product is increased after oil products are oxidized, the total base number decrease caused by the increase of the acid number can also be considered as a consideration of the oxidation degree, and the decrease of the total base number can be applied as an auxiliary means in the formula development process.

Screening experiment of antioxidant in antioxidant dispersant composition

A modified oxidation test was conducted by compounding a zinc salt of sulfur-phosphorus bis-octyl primary alkyl (T203), an aminothioester (T323) as a multifunctional additive, and a thiadiazole derivative (T561) as antioxidants, adding the antioxidants at different compounding ratios to a base oil containing 7.4% of a metallic detergent composition and 7.2% of an ashless dispersant, and measuring the oxidation induction period and the scuff diameter, and the results are shown in Table 4:

TABLE 4 Oxidation test results and Oxidation Induction period versus scrub Spot diameter

Additive/project	Formulation 1	Formulation 2	Formulation 3	Formulation 4	Formulation 5
						Detergent composition, an	7.4	7.4	7.4	7.4	7.4
Ashless dispersant,%	7.2	7.2	7.2	7.2	7.2
						T203，％	1.00	1.20	1.25	1.30	1.4
T323，％	0.7	0.5	0.5	0.4	0.3
						T561，％	0.1	0.1	0.05	0,1	0.1
Base oil,% of	83.6	83.6	83.6	83.6	83.6
						Improved oxidation test scoring	350.21	142.52	175.35	180.65	115.74
PDSC(min)	41.20	41.53	39.82	41.28	34.63
						D392N60min	0.42	0.41	0.39	0.42	0.41

The antioxidant is selected mainly by considering the antioxidant property of the formula and simultaneously considering the influence of the formula on the abrasion resistance. As can be seen from Table 4, the composition of the oil and the properties exhibited by it are very complex, and we cannot simply pursue a certain property optimization, but need to balance the properties. For example, the PDSC oxidation induction period of formulation 3 performed poorly, the improved oxidation test results were intermediate, but the antiwear results were better.

In addition, liquid octyl butyl diphenylamine (IRGANOX L57) and liquid high molecular weight phenol antioxidant (IRGANOX L135) are selected as auxiliary antioxidants to carry out screening experiments, and the composite effect of different antioxidants is investigated.

TABLE 5 screening test of liquid octylbutyldiphenylamine and liquid high molecular weight phenolic antioxidants

Table 5 shows that the addition of T561 results in better oxidation test results, improved detergency and the advantage of L135 to control viscosity increase. The addition of auxiliary antioxidants IRGANOX L57 and IRGANOX L135 is beneficial to improving the comprehensive performance of the diesel engine oil of the railway locomotive.

Example 1:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 79.56% of polyisobutenyl succinimide, 13.64% of zinc di-octyl sulfur-phosphorus zinc salt, 3.4% of aminothio ester (T323), 2.27% of liquid high molecular weight phenolic antioxidant and 1.13% of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.7 percent of the antioxidant dispersant composition prepared in the embodiment, 44.5 percent of high-temperature detergent and 1.83 percent of pour point depressant.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the example is 16.4% and the base oil is 83.6%.

Example 2:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 80.00 percent of polyisobutenyl succinimide, 16.00 percent of zinc di-octyl-sulfur-phosphorus zinc salt, 1.14 percent of octyl butyl diphenylamine, 2.28 percent of liquid high molecular weight phenolic antioxidant and 0.58 percent of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.5% of the antioxidant dispersant composition prepared in this example, 44.4% of the high-temperature detergent, and 1.83% of the pour point depressant.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the embodiment is 16.35% and the base oil is 83.65%.

Example 3:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 79.5 percent of polyisobutenyl succinimide, 18.5 percent of zinc sulfur phosphorus-bis-octyl alkyl salt and 2.27 percent of octyl butyl diphenylamine.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.38 percent of the antioxidant dispersant composition prepared by the embodiment, 44.8 percent of high-temperature detergent and 1.82 percent of pour point depressant.

The locomotive diesel engine oil comprises the following components in percentage by mass: 16.5 percent of diesel engine oil complexing agent for railway locomotives and 83.5 percent of base oil.

Example 4:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 80.01% of polyisobutenyl succinimide, 13.33% of zinc di-octyl sulfur-phosphorus zinc salt, 3.33% of aminothio ester (T323), 2.22% of liquid high molecular weight phenolic antioxidant and 1.11% of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 54.0% of the antioxidant dispersant composition, 44.3% of the high-temperature detergent and 1.79% of the pour point depressant prepared in the embodiment.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the example is 16.7% and the base oil is 83.3%.

Example 5:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 80% of polyisobutenyl succinimide, 13.32% of zinc salt of sulfur-phosphorus-bis-octyl alkyl, 5.56% of aminothio ester (T323), 0.56% of zinc diamyl dithiocarbamate (VANLUBE AZ) and 0.56% of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.91 percent of the antioxidant dispersant composition prepared in the embodiment, 44.3 percent of high-temperature detergent and 1.79 percent of pour point depressant.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the example is 16.7% and the base oil is 83.3%.

Example 6:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 80.02% of polyisobutenyl succinimide, 13.32% of zinc dithiophosphate dicapryl alkyl, 3.33% of aminothio ester (T323), 2.22% of zinc diamyl dithiocarbamate (VANLUBE AZ) and 1.11% of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.91 percent of the antioxidant dispersant composition prepared in the embodiment, 44.3 percent of high-temperature detergent and 1.79 percent of pour point depressant.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the example is 16.7% and the base oil is 83.3%.

Example 7:

the antioxidant dispersant composition for the locomotive diesel engine oil comprises the following components in percentage by mass: 80.00 percent of polyisobutenyl succinimide, 11.11 percent of zinc dialkyl dithiophosphate, 5.56 percent of aminothio ester (T323), 2.22 percent of zinc diamyl dithiocarbamate (VANLUBE AZ) and 1.11 percent of thiadiazole derivative.

The compound agent for the diesel engine oil of the railway locomotive comprises the following components in percentage by mass: 53.91 percent of the antioxidant dispersant composition prepared in the embodiment, 44.3 percent of high-temperature detergent and 1.79 percent of pour point depressant.

A locomotive diesel engine oil comprises the following components in percentage by mass: the compounding agent prepared in the example is 16.7% and the base oil is 83.3%.

The railway locomotive diesel engine oils of examples 1 to 7 were subjected to a PDSC pressure differential scanning calorimetry experiment, an improved multi-metal oxidation test method, and a varnish formation simulation test method, respectively, to determine the oxidation induction period, varnish formation performance, and oxidation resistance of the corresponding oils, and the results are shown in table 6.

TABLE 6 comparison of the Performance results of the oils of examples 1-7

As can be seen from Table 6, the antioxidant dispersant compositions of different compositions were compounded with the detergent dispersant composition and the pour point depressant, and blended with the base oil in an amount of 16.35 to 16.7% to obtain a diesel engine oil for railroad locomotives. The compositions of the antioxidant dispersion compositions in the above 7 examples are different, but the antioxidant and dispersion results are better, and the applicant selects the scheme of example 7 to perform practical use tests to verify the performances of the oil products, especially in antioxidation and viscosity increase control.

Experiment for investigating comprehensive performance of railway engine oil

1. Improved oxidation experiments

An improved oxidation test was conducted using the engine oil of example 7 as the experimental example and the imported fifth generation oil product meeting the LMOA requirements of the American locomotive maintainer Association as comparative examples 1 and 2 to verify the performance of the oil to which the antioxidant dispersant composition of the present invention was added, with the results shown in Table 7.

TABLE 7 comparison of results of oxidation experiments of comparative examples 1 to 2 and experimental examples

Item	Comparative example 1	Comparative example 2	Examples of the experiments
				Copper sheet weight loss score	1.2	1.7	8.8
Lead sheet weight loss scoring	120.14	139.05	80.56
				Viscosity increase score	18.08	49.51	39.32
Colorimetric scoring	2.47	2.67	2.90
				Total score	141.89	193.13	131.58

As can be seen from Table 7, the oil prepared by the two complexing agents imported from the United states is adopted in the comparative example, and compared with the oil of the experimental example, the result of the oxidation resistance test of the experimental example is better.

2. Railway engineering driving test

Kinematic viscosity is one of the main characteristic parameters of engine oils. Under normal engine conditions, the change in kinematic viscosity of the engine oil reflects changes in the degree of oxidative decay of the oil, the degree of soot accumulation, volatilization of light components in the lubricating oil, shear of the viscosity index improver, and the like. Therefore, proper viscosity is an important indicator to ensure proper operation of the locomotive. Particularly under severe operating conditions of a railway locomotive engine, the increase in kinematic viscosity of the engine oil is undoubtedly a major cause of the influence on the performance of the engine oil.

The applicant has verified the performance of the product by means of a two-year driving test, with a vehicle using a railroad locomotive four-generation oil as a control vehicle and a vehicle using an oil formulated with the composition of the invention (example 7) as a test vehicle. In each test, the kinematic viscosity at 100 ℃ of the engine oil reaches 18.5mm²At/s, the engine oil needs to be replaced.

FIG. 1 is a graph of the operating mileage versus kinematic viscosity of a test vehicle. Since the test protocol provides for the collection of one oil sample at 1 kilometre, the time in the figure is the approximate time estimated by the crew. It should be noted from fig. 1 that, first, the viscosity of the test car 1 was still at a normal level (14.92 mm) when the second oil change period was run to 4 km²S) but the test is stopped halfway due to the service section's service plan. Second, the kinematic viscosity at 100 ℃ of the test vehicle 2 is only 13.36mm when the test vehicle is operated to about 4 kilometres in the first oil change period²S, but still above the lower limit of the oil change indicator due to concerns about smokeThe soot amount is larger, the insoluble matter is higher to influence the operation, and the engine section is changed with new oil to operate again, so the operation mileage in the period cannot reflect the actual oil change period.

FIG. 2 is a graph comparing vehicle operating range to kinematic viscosity. As can be seen from FIG. 2, the shortest comparative oil reaches the oil change index within 1 kilometer, the oil change period of most vehicles is 3-4 kilometers, the longest oil change period (comparative vehicle 3) is 6 kilometers, and the viscosity of the vehicle is at a normal level (16.3 mm) when the vehicle runs to 2 kilometers in the second oil change period²S) and also due to the maintenance schedule of the crew section.

The statistical results of the amount of lubricant replenished per ten thousand kilometers for each test car and the comparative car are shown in table 8:

TABLE 8 statistical table for oil supply of each vehicle per ten thousand kilometers

Table 8 shows that the average oil supply of 77.36kg per ten thousand kilometers of the comparative vehicle 3 is at the highest level of the oil supply; the average oil supplement amount of the test vehicle 3 per ten thousand kilometers is 13.71 kilograms, and is at the lowest level of the oil supplement amount. Wherein, the operating mode of experimental car 3 is harsher, and the operating mode of contrast car 3 is gentlest, and this will have certain influence to actual oil change period, but the result of influence can't be quantitative.

The applicant summarizes the oil change periods of the comparison vehicle and the test vehicle, calculates the oil change period of each vehicle, and the specific comparison is shown in table 9.

TABLE 9 summary of test procedures vehicle oil change periods

The results in table 9 show that the average oil change period for the three control cars was 36603 km; the average oil change period of the three test vehicles is 65916 km, which is 1.8 times that of the comparison vehicle. If the working condition of the comparison vehicle 3 is removed, the oil change period of the other two comparison vehicles is 27087 km; except for 3 harsh working conditions in the test vehicle, the oil testing viscosity changes of other two test vehicles are relatively smooth, and the oil change period reaches 80444 kilometers.

The running tests of the long period show that the oil added with the railway locomotive diesel engine oil complexing agent has better performances of dispersibility, viscosity maintenance and the like, so that the oil change period of the oil is improved.

The compounding effect of various dispersion and antioxidant compositions is closely related to other performances of the diesel engine oil of the railway locomotive, and the composition of the composition is determined by taking the principle of solving the mutual inhibition of the dispersibility, the oxygen resistance, the high-temperature detergency, the wear resistance and the alkalinity retention on the compounding of the composition components. The applicant determines the compounding proportion of all additives through the tests of the improved evaluation method listed above and the auxiliary test method, and according to the antioxidant dispersant composition determined by the invention, other detergent dispersants and pour point depressants are compounded to prepare a complexing agent, and then an antifoaming agent and proper base oil are added, so that the formulas of 20W/40 locomotive multistage fifth-generation oil and modified fourth-generation oil with excellent performance are developed, and the mutual inhibition effect of the oxygen resistance, high cleanness, high abrasion resistance and high alkalinity required by the multistage fifth-generation oil on the compounding of the additive components is solved.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.