Failure and analysis of cylinder pulling of the ho

Marine diesel engine cylinder pulling failure and analysis

Abstract: This paper introduces the cylinder pulling phenomenon of marine diesel engine and the main external signs of this phenomenon; It also analyzes the internal mechanism and external causes of cylinder pulling phenomenon, and further puts forward different countermeasures for different faults in these different situations

key words: marine diesel engine cylinder pulling phenomenon lubrication countermeasures

Chinese figure classification number: u676.5 document identification code: a article number: (2006)

I. cylinder pulling brief introduction

cylinder pulling phenomenon is a very harmful and common engine fault in the production and operation of marine diesel engine. The amount of wear produced during cylinder drawing is very large, which can reach dozens or even hundreds of times the normal wear. According to the degree of damage, the cylinder pulling of diesel engine can effectively improve the stability of power system operation, adjust the frequency, compensate for load fluctuations, reduce the power supply cost, and improve the utilization rate of power equipment. It can be divided into several kinds of faults, such as scratch, scratch and bite. The first two are slight cylinder pulling behaviors, which can usually be repaired by themselves. If the situation is found in time and the fault is eliminated, large loopholes and losses can be avoided. If the cylinder pulling becomes more and more serious, the piston will stick to the cylinder wall. If it is light, the piston and cylinder will be damaged, if it is heavy, the piston will bite, the piston will be stuck in the cylinder liner, the diesel engine will shut down, and the crankshaft will not move. The piston or connecting rod is broken, and the machine is damaged, resulting in a major accident. Therefore, it is of great significance to analyze the formation mechanism of diesel engine cylinder pulling fault, find out early prediction and correct countermeasures, correctly manage and use the diesel engine, improve reliability and prolong service life, and improve the ability of managers to eliminate and respond to faults

II. Signs of cylinder pulling

the so-called "upgrading the relationship between the two countries to a comprehensive strategic partnership" cylinder pulling phenomenon is a fault in the operation of the diesel engine. When cylinder pulling occurs, the external signs are: 1. The engine sound is dull and abnormal, with clattering or abnormal sound. 2. The engine vibrates. 3. The cylinder liner and piston are strained. During the compression and power stroke, there is cross gas in the cylinder, the oil load is stable, the operation is simple and serious, and the oil consumption increases. 4. Abnormal temperature. The exhaust temperature rises, the cooling water temperature rises, the lubricating oil temperature increases significantly, the speed is unstable, it is difficult to start, the crankcase outlet smokes, the operation is weak, the power is insufficient, and the diesel engine power decreases

after cylinder drawing, remove the piston connecting rod and observe the flake or strip blue stripes on the working surface of piston ring cylinder wall along the direction of piston movement, forming a certain area of galling, and its surface hardness is higher than the original matrix structure. Accompanied by discoloration (dark red or blue), even the piston ring is broken, stuck, the piston or connecting rod is broken, and the machine is damaged

III. mechanism of cylinder pulling phenomenon

as we all know, marine diesel engine is a kind of thermal power machinery, which has very poor working conditions and bears high thermal load and mechanical load. The combustion chamber is a place for diesel combustion and working medium expansion. The piston, cylinder liner and cylinder head are the main components of the combustion chamber, and their working environment is high temperature, high pressure and chemically corrosive mixed oil and gas directly act on the combustion chamber components. If the maintenance is not good, the cylinder pulling failure occurs from time to time

modern research shows that the lubrication state of piston (ring) - cylinder liner of diesel engine is in the state of mixed lubrication model, that is, sometimes in the state of fluid lubrication, sometimes in the state of boundary lubrication. Generally speaking, the internal mechanism of cylinder pulling fault is that the working surface between the inner wall of the cylinder and the piston ring and the piston has a certain hardness and surface roughness. It works together under certain temperature conditions, and the oil plays the role of lubrication, cooling, cleaning and sealing

if for some reason, the oil film becomes thinner or damaged, and dry friction or semi dry friction occurs due to poor lubrication, resulting in local high-temperature adhesion and wear. The deterioration and interruption of lubricating oil film between piston and cylinder liner is a necessary prerequisite for cylinder pulling. Once the lubricating oil film between the piston and the cylinder liner is interrupted, the metal on the surface of the two will change from the original liquid friction to the dry friction or semi dry friction between solids. Due to the friction heat generated by the high-speed movement of the friction pair surface, the high temperature of such heat accumulation will exceed the melting point of the metal, causing micro melting, tearing off and finally welding of the piston or piston ring and the cylinder liner surface. When the piston moves, the fusion welding points on the two surfaces are pulled apart by the force and then cooled. In this way, the material on one surface transfers and adheres to the other sliding surface to form a hard layer or falls off as abrasive. If the oil film can be remedied and restored in time, it can play the role of cleaning and cooling, the temperature will drop, and the tiny molten part will fall off without expansion. If the oil film recovers slowly, the molten expansion will lead to a wide range of abnormal wear, the cylinder wall, piston and piston ring will be rapidly and seriously damaged, showing a molten flow state on the surface of the cylinder wall, showing uneven and irregular edge grooves and folds, which will continue to develop and produce cylinder pulling. In addition, the damage caused by hard particles entering the friction area from the engine oil and air pipeline will also promote the occurrence of cylinder pulling

other scholars believe that "the increase of friction interface temperature evaluation by 15.2534 million yuan leads to adhesion, and the strong friction on the friction pair surface leads to the strong friction on the hardened surface, leading to the rupture or even fracture of the hardened phase. The cylinder pulling first occurs in the local area with large contact load, and then further expands. From the perspective of wear mechanism, it is a sudden change from normal wear to serious abrasive wear."

IV. other relevant factors affecting cylinder drawing

there are many and complex factors affecting cylinder drawing, and there are often mutual influences and constraints between various factors, which are uncertain. But the root cause is poor lubrication and excessive local load. The major aspects can be summarized as follows: the structural design of piston group and cylinder liner; Technological level; Installation quality problems; Running in procedure; Selection of lubricating oil; Fuel handling, use and maintenance. There are many reasons for each aspect, for example: only one of the reasons for piston group may be: (1) improper selection of piston material or heat treatment; The hardness of the piston surface has a great influence on the cylinder drawing