Gasoline engines generally use a multi-point direct injection method to increase their compression ratios, and turbochargers are used to increase their inflating coefficients. Diesel engines commonly use boosting and booster intercooling to increase engine power. Exhaust turbochargers are currently the most commonly used superchargers. Taking a diesel engine as an example, the power and torque of a supercharged diesel engine of the same displacement is 10% to 20% larger than that of a normal type; the power/torque of a supercharged medium-cooled diesel engine is larger than that of an ordinary type of the same displacement. 30% to 50%. Due to the high inflation coefficient of turbocharged and supercharged intercooled diesel engines, combustion is more complete and less pollution is emitted, which can meet the needs of energy conservation and environmental protection.
Because the torque and power of the supercharged and turbocharged intercooled engine with the same displacement are larger than those of the common type, the requirements on the quality of the material and the burning and polishing materials are also high, and there are also strict requirements on the operation. The quality of the material is determined by the engine manufacturer. The fuel requires the use of precipitated low-sulfur, high-quality diesel; the lubricant, the engine oil, due to the increased power and torque of the engine, the pressure between the moving parts and the friction pair increases, and the oil forms between the friction pairs. The oil film is not destroyed under all conditions of the engine, effectively separating the friction pair and preventing dry friction, which is the key to the reliability and working life of the engine. Therefore, the choice of lubricating oil must be in accordance with the quality level provided by the engine manufacturers or the use of oil higher than the quality level required by the manufacturer to ensure the normal operation of the engine.
Before starting the engine, first check the engine's oil, cooling () water is sufficient, whether the tubing, wires aging damage, fan belt tightness is appropriate and so on. When starting, try to use the starting device on the car to start the engine as quickly as possible to reduce the loss of the battery and the motor.
(1) When the cold car starts, it is not allowed to increase the throttle. Because there is a process between the oil and the friction surface of the friction oil, the engine will be throttled immediately when it is started. This will cause the oil film between the friction surfaces to be destroyed, resulting in dry grinding. Accelerate the wear of the parts and reduce the service life of the engine. In severe cases, it will lead to pulling cylinders and burning bearings.
(2) When the engine is running at a high speed, the engine cannot be turned off immediately. Because the temperature of the combustion chamber and the friction pair surface is high when the engine is running at a high speed, most of the heat is taken away by the circulation of cooling water and lubricating oil to maintain its temperature. Design allowed range. Sudden flameout, partial cooling of the cooling water around the combustion chamber may occur, causing the cooling water to overflow and decrease. In severe cases, the engine will be deficient in water; the high temperature of the friction surfaces will thin the lubricating film between them, resulting in the next The surface is lubricated poorly at startup, which reduces the life of the engine.
The above two points are more important for turbocharged and supercharged intercooled engines. In addition to the above, turbochargers for supercharged and turbocharged intercooled engines have high speeds of 80,000 to 120,000 r/min during high-speed operation of the engine. Its bearings rely on lubricating oil to lubricate and dissipate heat. Immediately after the engine is started, the throttle is rapidly added. The turbocharger of the engine enters a high-speed operating state because the lubricant has not yet reached, causing the bearing to burn; the engine suddenly switches off when the engine runs at a high speed, and the turbocharger inertia due to its high-speed rotation , Will make it continue to run for a period of time, in the case of lubrication and cooling without circulating lubricant, the bearing's oil film will soon be destroyed, or even evaporated, and the bearing burned. Therefore, at least 2 to 3 minutes of idling can be extinguished before it can cause accidental damage.
The influence of the operating temperature of the engine on its service life The operating temperature of the engine directly affects the service life of the engine. Maintaining the normal operating temperature of the engine is a major factor in prolonging the service life of the engine. At present, the design working temperature of a car engine is generally 80 to 90°C, that is, the engine can exert its best performance during this period of time. When the temperature is too low, the mixture of the engine is not fully burned, and the water vapor in the exhaust gas after combustion easily solidifies on the cylinder wall, resulting in water droplets. The oxidation reaction between the water droplets and the cylinder wall generates an oxide film; the temperature is too high and the exhaust gas directly contacts the cylinder. The wall reacts chemically to produce an oxide film, so that the piston ring of the engine constantly scrapes it during its reciprocating motion. The oxide film is continuously generated and then scraped away. This will greatly reduce the service life of the engine. In addition, when the engine temperature is too high, the carbon monoxide in the emissions increases, and when the temperature is too low, the amount of hydrocarbons discharged will increase, which will affect the environmental protection and energy conservation.
The impact of the selection and degraded use of lubricating oil on the service life of the engine 1. The influence of the choice of lubricating oil on the service life of the engine The early wear and abnormal wear of the engine have a great influence on the lubricating oil. Engine oil is commonly referred to as engine oil. The importance of engine oil has been mentioned previously. Its role is to lubricate the surfaces between the friction pairs of the moving parts, flush the surfaces of the friction pairs, and remove the heat, forming an oil film between the friction pairs. The working environment of the oil film is very harsh, and it must withstand the impact of high temperature, high pressure and reciprocating motion of the engine without being damaged, effectively separating the moving parts, reducing wear to zero wear.
The engine oil is generally composed of base oil and additives (except synthetic oil). The composition of the additive directly determines the quality of the engine oil. The evaluation of engine oil quality indicators includes: (1) SAE proposed viscosity classification of engine oil in 1911, namely SAE0 ~ SAE60, SAE0 is the most dilute, the best low-temperature flow performance, SAE60 is the thickest, At high temperatures, the film strength is high. Under normal circumstances, the thicker the oil, the greater the film strength. Due to the study of high-temperature tackifiers, there are multiple oils, SAE15W ~ 40 are common, that is, the oil has SAE15 fluidity at low temperatures, SAE40 viscosity at high temperatures, the greater the span, the greater the performance superior. (2) The American Petroleum Institute (API) proposed in 1970 that engine oils are classified according to their use, ie, APISA, APISB, APISC, API SD..., APICA, APICB, APICC, APICD, etc. The first letter S represents gasoline engine oil. Domestic gasoline engine oil is also represented by Q, C is diesel engine oil, and the second letter represents its quality level in English alphabetical order, and the higher the letter, the higher its quality level. Now marked "APICF/SE" means that the oil is preferably used in diesel engines, reaches the CF level, and can also be used in gasoline engines. It is used in gasoline engines only to reach the SE level; if it is marked "APISG/CD", it means that The oil is preferred to the gasoline engine and reaches the SG level. It can also be used in diesel engines, reaching only the CD level.
Do not make mistakes when using, only the correct choice can give full play to the best performance and use of oil. The specifications of the oil used by the engine and the oil mileage are generally stated in the operating instructions of the engine. Experience shows that, under normal conditions, the higher the oil quality level, the higher the oil film strength, the better the anti-corrosion and anti-oxidation performance, the better the clean dispersibility, high-temperature anti-evaporation and so on, and the oil change period can be longer. That is, the use of oil higher than that required by the engine instruction manual, that is, the degraded use of the oil, can not only reduce the wear of the engine, but also appropriately extend the oil change interval.
The degraded use and value analysis of oil in the automotive technology management process, through the analysis of the engine's early wear and lubricant lubrication mechanism, and according to the characteristics of the lubricant oil, the author's company put forward a strict oil in 1995. Management and engine oil decommissioning recommendations, and piloted in the team, the effect is good, to achieve the desired goal, began to promote the use of 1998. At that time, the main engines used for vehicles were Isuzu, Nissan, and Xichai. The engine oil required by the engine instruction manual is APICC or APICD diesel engine oil. After researching and combining the market conditions of lubricants at that time, the “Haipai†API CF grade engine oil was uniformly used. The required oil change range of the engine is 6,000 to 8000 km. The mileage available for the test exceeds 30,000 km. For insurance purposes, the oil change mileage is set at 20,000 to 22,000 km. The average mileage of the engine (the mileage when the dismantling is reached) Over 400,000 km, there is no phenomenon of early wear and abnormal wear. The average mileage of the engine has been extended by more than 100,000 km compared to that of the fraternal unit. This not only prolongs the mileage of the engine, saves maintenance costs, but also reduces the number of breakdowns and maintenance. Car day. Due to the high quality grade of lubricant, its oil film has high extreme pressure strength, good anti-corrosion and anti-oxidation performance, good high temperature and clean dispersibility, high temperature anti-evaporation, and high-speed continuous use performance of the engine. Therefore, in the degraded use of oil, Although the price of oil has increased by 10% to 15%, the mileage of the engine has increased by about 200%, and mileage has increased by about 50%, which greatly reduces the cost of using the car.
In addition, according to the differences in the characteristics of various lubricants and production conditions, strict management of the oil, the engine oil can not be mixed. The formulation of oil additives for each brand and each quality grade is different. Once the oil is used in combination, their respective additives may interfere with each other, causing the oil to produce gel, precipitate, etc., which will reduce the quality of the oil and affect the use of the engine. life. Generally, after selecting a brand or grade of engine oil that is suitable for the use of the vehicle, do not change it. For example, if you use another brand or grade of engine oil for some reason, the time for the first oil change should be shortened properly. It is impossible to drain the old oil when it is oil, so as to prevent the engine oil from deteriorating early and affect the service life of the engine.
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