The amount of petroleum lubricating oil accounts for more than 90% of the total amount, so lubricating oil is often referred to as petroleum lubricating oil. Mainly used to reduce the friction between the moving parts of the surface, while the machinery and equipment have cooling, sealing, corrosion, rust, insulation, power transmission, cleaning impurities and so on. The lubricating oil fraction and residual oil fraction from the crude oil distillation unit are mainly used as raw materials. The most important properties of lubricating oils are viscosity, oxidation stability and lubricity, which are closely related to the composition of lubricating oil fractions. Viscosity is an important quality indicator that reflects the fluidity of a lubricant. Different conditions of use have different viscosity requirements. Heavy duty and low speed machines use high viscosity lubricants. Oxidation stability means that the oil in the use of the environment, due to temperature, oxygen in the air and the catalytic performance of metal oxidation performance. After the oil is oxidized, fine asphaltene-based carbonaceous materials are produced depending on the conditions of use, which are viscous lacquer-like substances or paint films, or viscous water-containing substances, thereby reducing or losing their performance. Lubricity represents the antifriction properties of the lubricating oil. The concept of a lubricant additive is one or more compounds added to the lubricant to give the lubricant some new properties or to improve some of the properties already present in the lubricant. Additives are mainly divided into functional categories of antioxidants and metal deactivators, extreme pressure antiwear agents, friction modifiers, detergents, foam inhibitors, rust inhibitors, antioxidants, flow point improvers, and viscosity index enhancements. Agents, anti-emulsions and other types. The additives sold in the market are generally composite products of the above single additives. The difference is that the composition of the single additive is different and the ratio of several single additives within the compound additive is different.
When the engine is running, dry friction will occur if some frictional areas are not properly lubricated. Practice has proved that the heat generated by dry friction in a short time is enough to melt the metal, causing damage or even stuck in the mechanical parts. Therefore, it is necessary to give good lubrication to the friction parts in the engine. When the lubricant flows to the friction site, it will adhere to the friction surface to form a layer of oil film, reducing the friction between the friction parts, and the strength and toughness of the oil film is the key to play its role in lubrication. However, it cannot be used in too large an amount, because when the amount is too large, there will be a resistance to the square relationship, which has a great influence on the rotation speed. Therefore, special attention must be paid to the amount of use.
Only a small part of the heat generated by the combustion of fuel in the engine is used for power output and frictional resistance consumption and the drive of the auxiliary mechanism; most of the rest of the heat is also discharged by the cooling medium in the engine Take part. Excess heat in the engine must be exhausted, otherwise the engine will burn out due to excessive temperature. On the one hand, it is accomplished by the engine cooling system. On the other hand, it absorbs heat from the surfaces of cylinders, pistons, crankshafts, etc., and then radiates oil into the oil pan.
In the engine work, there will be a lot of dirt. Such as inhalation of air in the sand, dust, carbon dioxide gas mixture formed after combustion, lubricating oil after the formation of the gel-like material, friction between the metal parts generated by the friction and so on. These dirt will adhere to the friction surface of the parts. If they are not cleaned, they will increase the wear of the parts. In addition, a large amount of gum can cause the piston rings to stick together and cause the engine to malfunction. Therefore, these contaminants must be cleaned in a timely manner. This cleaning process is accomplished by circulating the lubricant in the body.
There is a certain gap between the cylinder and the piston of the engine, the piston ring and the ring groove, and between the valve and the valve seat, so as to ensure that there will be no seizure between the pairs of movements. However, these gaps can result in poor sealing of the cylinder. The result of the leak in the combustion chamber is to reduce the cylinder pressure and engine output power. The oil film formed by the lubricating oil in these gaps ensures the tightness of the cylinder, maintains the cylinder pressure and engine output, and prevents exhaust gas from entering the crankcase.
When the engine is in operation or stored, the atmospheric, lubricating oil, moisture in the fuel, and acid gases generated by combustion will cause corrosion and corrosion to the parts, thereby increasing the damage of the friction surface. Lubricating oil film formed on the surface of the machine parts can avoid direct contact between the machine parts and water and acid gas to prevent corrosion and corrosion.
Elimination of impact load
At the end of the compression stroke, the mixture gas starts to burn and the cylinder pressure rises sharply. At this time, the lubricating oil in the bearing gap will relieve the impact load on the piston, the piston pin, the connecting rod, the crankshaft, and other mechanical parts, so that the engine can work smoothly and prevent the metal from directly contacting and reducing the wear.
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