Cylinder wear law
Wd615.67 Wear of the engine cylinder in use is not uniform. The general rule is that along the axis of the cylinder, above the cylinder liner, the first ring of gas is located slightly below the top dead center, where the wear is greatest, and the piston ring wears minimally below the bottom dead center. From the worn cross section, the cylinder is ground to a non-standard cylindricity. The general wear condition is that the wear of the first cylinder and the sixth cylinder of the engine is more severe than that of other cylinders, which is mainly caused by poor cooling.
Causes of Wear on the Engine Cylinder There are three main reasons for engine cylinder wear: mechanical wear, abrasive wear, and chemical corrosion.
(1) Mechanical wear:
Mechanical wear is caused by mechanical friction. The degree of mechanical wear is affected by the machining accuracy of the cylinder and piston rings, the quality of the fit, the lubrication conditions, the operating temperature, and the mutual pressure in the friction. When the engine is working, the upper temperature is high, the lubricant is affected and thin, the quality of the oil film is poor, the back pressure of the first piston ring (high pressure gas enters the piston ring groove, and the piston ring is tightly pressed on the cylinder wall) The largest, therefore, is that the wear is greatest at the first piston ring and slightly below the cylinder, and the wear below it becomes smaller.
(2) Abrasive wear
Abrasive wear is the main wear. Abrasives are formed by the mixing of metal impurities mixed in the engine oil and the impurities carried in the air, which can accelerate the wear of the machine parts. As the air intake process, the pressurized intake air directly into the cylinder wall opposite the intake valve, when the engine is running at low temperatures, the diesel spray is not good, diesel oil particles that have not fully burned dilute the oil, so that the oil Thinning, damage the film. At the same time, due to the breakage of the air filter element, dust, sand, etc., brought into the intake air flow adhere to the cylinder wall opposite the intake valve, resulting in severe abrasive wear. Abrasive wear not only results in greater wear of the slightly lower dead center of the first piston ring above the cylinder, but also makes the cross section of the cylinder oval. The main causes of abrasive wear are: the air filter element is damaged, the hose from the supercharger to the intercooler or the supercharger to the intake tube falls off, cracks or disconnects, and the air short-circuits into the cylinder and forms a serious abrasive wear; Some users have also overemphasized the replacement of engine oil by quality. The engine oil has been used for too long. The oil has deteriorated, thinned, and impurities have increased. The metal impurities have caused severe abrasive wear. In the unit that the test equipment does not have, it is best to replace the oil on a regular basis. Each time the secondary maintenance (12000km) of oil and oil filter cores and air filters are the best maintenance methods.
(3) Chemical corrosion
When the temperature of the cylinder wall of the engine is low and the pressure in the cylinder is high, water vapor in the cylinder forms water droplets on the cylinder wall. These water droplets come into contact with the exhaust gas to form acidic substances that attach to the cylinder walls and cause corrosion to the cylinder. The lower the operating temperature of the cylinder, the more easily acidic substances are formed and the greater the corrosion effect. Corrosion wear is mainly caused by improper operation. The correct operation is that after starting the starter, idle for a few minutes. After the water temperature and oil pressure are normal, the engine speed is gradually increased to maintain the engine temperature. The engine water temperature during driving is preferably 80~90°C. Low temperature driving is very unfavorable to the engine, and the corrosion wear is also increased.
In order to ensure the normal operation of the engine and prevent early wear of the cylinder, the following points are made:
(1) After the engine is started, idle for a few minutes, wait until everything is normal, increase the engine speed, increase the load, maintain the normal operating temperature of the engine, and resolutely stop low-temperature driving.
(2) Timely cleaning of the air filter element should be promptly replaced if it is damaged; it is best to replace the air filter element every time the second warranty (12,000 km operation) is completed.
(3) Ensure the use of qualified cd-class turbocharged diesel engine oil and implement oil replacement on schedule to ensure the cleanliness and quality of engine oil. Every time the second change of oil and oil filter.
(4) Check the connecting part of the supercharger to the intercooler to the intake pipe frequently to prevent the connecting hose from loosening and breaking and ensure that the air enters the cylinder after filtering.
In short, pay attention to the correct operation and maintenance, pay attention to the use of the vehicle's walking period, the early wear of the cylinder can be effectively prevented.
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