Analysis of abnormal wear mechanism of the hottest

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Analysis of abnormal wear mechanism of engine

automobile is an electromechanical product. With the increase of driving mileage, the technical status of automobile is constantly changing. Due to the wear of parts in 2014, the investment strategy is, deformation, fatigue, corrosion and other reasons, so that its power, economy and handling are deteriorated, until it loses its normal working ability. 3. The extreme wear of the working surface of engine parts at room temperature is one of the main reasons for the frequent failure of vehicles and the deterioration of technical conditions

abnormal engine wear often occurs in rotating crankshaft and bearing bush, reciprocating piston and cylinder, and valve components bearing impact load

1 wear of crankshaft and bearing bush

during the working process of the engine, the crankshaft and bearing bush bear a lot of mechanical load and thermal load, the lubrication conditions are poor, the work and surface are not easy to form a strong oil film, and the anti-wear alloy layer is very easy to be burned (that is, it is often said that the Japanese Wisconsin company pushed out GT anti cutting gloves as "burning bush"), or the alloy layer falls off. If the oil is too dirty, it will also cause the journal and bearing bush to scratch, causing early wear

1.1 Bush burning

the main reasons for engine Bush burning are as follows:

1.1.1 long-term overload operation of the engine

long-term overload operation of the engine or long-term operation in hot summer, resulting in excessive engine temperature, decreased oil viscosity, too low oil pressure, damage to the oil film, and the complete liquid friction between the shaft and the bearing bush changes to boundary friction or even dry friction, which eventually leads to the melting of the wear reducing alloy layer. After the fault occurs, a crisp and short abnormal sound can be heard at the lower part of the engine or at the oil filling port. They mainly include polyphenylene sulfide (PPS), polyimide (PI), polyether ether ketone (PEEK), polysulfone (PSF), polyarylate, liquid crystal polymer (LCP), high temperature nylon, fluoroplastics, etc. when checking the cylinder by cylinder fire (or oil) cut-off of the engine, it is easy to find the cylinder position of Bush burning or journal wear according to the intensity of the sound. In terms of the frequency of cylinder failure, the first cylinder is the most common

1.1.2 do not use lubricating oil according to regulations or use unqualified lubricating oil

unqualified lubricating oil contains more water and sundries, and has poor oxidation and corrosion resistance. It is easy to gel and deposit carbon in the process of use, and it ages and deteriorates quickly. In this case, when the engine runs at high speed, the viscosity of the lubricating oil decreases significantly, and the strength of the oil film formed is not enough, which worsens the lubrication condition of the bearing bush, and accelerates the abnormal wear of the bearing bush and the occurrence of Bush burning failure

1.1.3 the engine oil is not changed in time as required

the engine oil should be changed as required after the vehicle has driven a certain number of kilometers, especially when the vehicle often drives on Sandy and dusty roads and burns tiles for maintenance. Otherwise, due to the large increase in the content of impurities and metal wear debris in the engine oil, the engine oil will deteriorate quickly, which will aggravate the damage of oil film, increase the abnormal wear of bearing shells, and eventually lead to the ablation of engine bearing shells

1.14 engine oil is seriously insufficient

engine oil mainly plays the role of lubrication, cooling, cleaning, sealing, corrosion prevention, vibration reduction and noise reduction during engine operation. If the oil in the system is seriously insufficient, the friction surface of crankshaft journal and bearing bush is poorly lubricated and cooled, resulting in Bush burning failure at high temperature. The main reasons for the serious shortage of oil in the engine lubrication system are the blockage of the oil filter (generally, the oil filter should be replaced once every 5000km), the damage of the oil pump, the blockage or leakage of the oil pipe. The blockage is often caused by the dirty oil pan (generally, the oil pan should be cleaned once in 50000 km of running vehicles), or by the colloid produced by the synthetic cooling oil due to the high machine temperature. It can be seen that the performance of the cooling system will also lead to the failure of the lubrication system

1.1.5 the fitting clearance is too large

the automobile engine is used for a long time, causing the wear of the bearing bush and journal, and then causing the fitting clearance between the bearing bush and journal to increase. When the fit clearance is too large, the engine oil pressure drops, and the insufficient lubrication oil supply causes the engine Bush burning fault after reaching a certain degree

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