LNG vehicles are highly reliable, affordable and can effectively improve emissions with high environmental friendliness and safety. The development of LNG vehicles is a systematic project. Although the proportion of lubricants is small in the whole project, its importance Sex can not be ignored.
The difference between gasoline and diesel oil is that gas fuels have high purity, high thermal efficiency, high gas temperature and clean burning, but their lubricity is poor, which may easily cause bonding, friction, corrosion and corrosion wear etc. If an unsuitable lubricating oil is used, , The consequences would be unthinkable.Therefore, LNG vehicle technology transformation and renewal, necessarily accompanied by the development and application of LNG engine oil.
In practice, the modified or dual-fuel engine can not be put in place due to the compression ratio, the heating value of the mixed gas is 12% lower than that of the gasoline, the charging efficiency and the amount of air are reduced by 1 to 6%, and the intake air is only 89.8% , The use of ordinary engine oil, the total dynamic performance can be reduced 10 ~ 20%; due to high engine combustion temperature, high nitrogen oxides; LNG fuel itself has no lubrication, exacerbating the wear of the engine valve system.
What is the effect of using an improper lubricant?
First, the combustion chamber temperature easily oxidized, carbon deposition, the impact of emissions using ordinary steam / diesel oil too fast oxidation, resulting in deterioration of oil quality, viscosity or lubrication failure, high cylinder temperature carbon soot prone to lead to pre-combustion , Spark plug carbon will cause abnormal engine wear or failure.
Secondly, the valve components are easy to wear.The steam / diesel in the steam / diesel engine is sprayed into the cylinder in the form of small droplets, which can lubricate and cool the components such as the valve and the valve seat, while the LNG enters the cylinder in a gaseous state , Do not have the liquid lubrication function, easy to make the valve, seat and other parts dry and without lubrication, easy to produce bonding and wear.Under the action of high temperature, ordinary engine oil high ash additive can easily generate hard deposits on the surface of engine parts, Wear and tear, spark plug plugging and valve coke, causing the engine knock, ignition failure and valve flameout; resulting in decreased engine power, power instability, and even shorten the life of the engine.
Third, the formation of harmful substances. The use of ordinary oil exhaust emissions of nitrogen oxides can not solve the excess, accelerate the generation of sludge, will result in clogged oil or generate paint and other harmful substances .Especially equipped with EGR engine, extremely easy Resulting in decreased oil quality, filter clogging, viscosity and acid, base out of control and other trends.
Suitable sulphate ash content for LNG engine requirements applicable to its lubricating oil
Need to choose the appropriate sulfate ash (lower than the average index of internal combustion engine oil), to prevent engine knock and premature combustion, reduce engine valve system wear and tear, and will not cause the piston ring and top ring groove carbon increase.
Excellent clean dispersion
The choice of efficient detergent dispersant and low ash / base ratio ensures that valves, pistons, spark plugs and other components always maintain a high degree of cleanliness and reduce the generation of deposits such as carbon deposition, to avoid ignition due to carbon deposition spark plug Advance engine failure, especially high temperature dispersibility, in which ash-free high temperature detergent dispersant ratio higher than gasoline and diesel engine oil, to ensure the normal operation of the engine.Also can control the EGR exhaust gas recirculation device on the oil viscosity, the growth of soot.
Excellent corrosion resistance
Has a good ability to maintain the total base value to ensure that the engine does not produce too much in the course of the work of sludge, carbon and other harmful substances, but also at any time and gas fuel in the combustion process to reduce acid, reduce acid on Corrosion wear caused by bearings of engine pistons, cylinder liners and copper-lead alloys.
Excellent high temperature oxidation and nitrification resistance
Because LNG engines have higher thermal loads, hybrid flame propagation and longer flame duration, combined with lean fuel, aldehydes, ketones, acids, ester oxides and nitrates, oils Oxidation, nitrification accelerated aging of the oil deterioration, so the anti-oxidation of oil anti-nitration requirements.
Good lubrication performance
Since LNG enters the cylinder in the gaseous state and does not have the liquid lubrication function, LNG is more pure than CNG, so its own lubricating performance is poorer and the valve components are easily worn. The special lubricating oil can prevent the valve and the valve seat from being worn .
Lower phosphorus content
Special lubricants to control the lower phosphorus content in order to reduce the vehicle exhaust three yuan catalyst pollution.
Excellent anti-rust performance
Good anti-rust can effectively prevent engine copper-lead alloy bearing corrosion and corrosion wear.
High quality base oil
Base oil requirements through the depth of refining, quality and stability, high viscosity index, with good oxidation stability and nitrification stability, to ensure the extension of oil life.
In short, the particularity of the LNG engine determines its high quality requirements for lubricants.General lubricants can not meet their needs, not only deterioration in advance, but also may cause various parts of the wear and tear, neither can effectively play the role of oil, but also Will affect the engine life.
