Inspection and Maintenance Technology of Automobile Engine —— Inspection and Maintenance of Automobile Engine
For the automobile, the engine is the core component, which is related to the overall performance of the automobile and is very critical in the composition of the automobile. In order to ensure the normal operation of the car, it is necessary to carry out normal maintenance and maintenance on the start of the car, and detect and repair it in time when it fails. Through research, it is found that in the current inspection and maintenance of automobile engines, most faults are mainly manifested in seven parts, namely, crank-connecting rod mechanism fault, valve train fault, carburetor oil supply system fault, electronic fuel injection system fault, diesel oil supply system fault, lubrication system fault and cooling system fault. The faults of these seven parts belong to the common faults in the process of engine operation. In the inspection and maintenance of automobile engines, attention should be paid to the analysis and judgment of these faults, and detailed maintenance plans should be made to ensure that automobile engine faults are properly handled.
Keywords automobile engine detection and maintenance
1 overall structure analysis of automobile engine
For automobile engines, the whole structure is divided into two main mechanisms and five subsystems. Two of them mainly refer to crank-connecting rod mechanism and valve train, and five subsystems mainly refer to oil supply system, ignition system, cooling system, lubrication system and starting system.
Crank-connecting rod mechanism is the core of realizing heat energy conversion and the assembly basis of engine. In the power stroke, the crank-connecting rod mechanism converts the gas pressure generated by fuel combustion into the torque of crankshaft rotation through the piston and connecting rod, and then completes the three auxiliary strokes of air intake, compression and exhaust by using the inertia of flywheel. The crank-connecting rod mechanism consists of cylinder crankcase group, piston connecting rod group and crankshaft flywheel group.
The function of the valve train is to open and close the intake valve and exhaust valve in time according to the working sequence of the engine and the requirements of the working cycle of each cylinder, so that combustible mixture (gasoline engine) or fresh air (diesel engine) can enter the cylinders and exhaust the exhaust gas into the atmosphere.
The function of the fuel supply system of gasoline engine is to make pure air and gasoline into a proper proportion of combustible mixture according to the needs of different working conditions of the engine, and then send it to each cylinder for combustion, and then discharge the generated exhaust gas into the atmosphere. The function of diesel fuel supply system is to supply diesel and air to cylinders respectively, form mixed gas in the combustion chamber and burn it, and finally discharge the burnt exhaust gas.
The ignition system mainly refers to all the equipment in the gasoline engine that can ignite the combustible mixture in the cylinder by electric spark. Therefore, a spark plug is installed on the cylinder head of the gasoline engine, and the head of the spark plug extends into the combustion chamber, so that electric sparks can be generated between the spark plug electrodes on time.
The function of the cooling system is to dissipate part of the heat absorbed by the heated parts in time to ensure that the engine works at the most suitable temperature.
The function of lubrication system is to deliver a certain amount of clean lubricating oil to the surface of relatively moving parts to realize liquid friction, reduce friction resistance and reduce parts wear. And the surface of the part is cleaned and cooled.
The whole process from when the crankshaft starts to rotate under the action of external force to when the engine starts to idle automatically is called engine starting. The device needed to complete the starting process is called the starting system of the engine.
2 The necessity of regular inspection of automobile engines
Because the automobile engine is in a state of high temperature and high pressure during operation, the operating conditions are relatively bad. Long-term operation in this state will inevitably damage various mechanisms and systems of the engine. Therefore, in order to protect engine parts and prolong engine life, we must carry out regular inspection of automobile engines, and its necessity is mainly manifested in the following aspects:
2. 1 The overall structure of the automobile engine determines the necessity of regular inspection.
Because the overall structure of automobile engine is complex, it is mainly divided into two major mechanisms and five subsystems. In the process of operation, these mechanisms are interrelated and work together. Failure of any mechanism or system will cause the engine to be paralyzed and the engine cannot be used normally. Therefore, in order to ensure the normal operation of the automobile engine, it is necessary to test the engine regularly to detect whether there are faults and safety hazards in its main institutions and systems.
2.2 The working conditions of automobile engines determine the necessity of regular inspection.
In the automobile engine, the two major mechanisms and five subsystems are in the state of high temperature and high pressure during operation, and the working conditions are very bad, and the wear on the mechanisms and accessories is also relatively large. In this state, if the automobile engine is not overhauled regularly, the weakness of the mechanism and accessories will not be found in time, which will lead to engine operation failure and damage the overall life of the engine. Therefore, we should take regular inspection to check and maintain the engine.
2.3 The life of automobile engine determines the necessity of regular inspection.
In the process of automobile engine running, in order to ensure the normal operation of the engine and extend its life appropriately, it is necessary to carry out regular inspection according to the maintenance requirements and use needs. In the process of using automobile engines, regular inspection and maintenance are sometimes neglected, which leads to the damage of automobile engine mechanism and accessories, affects the overall service life of the engine and causes permanent damage to the engine. Therefore, in order to prolong the engine life, we should check the engine regularly.
3 Classification of common faults of automobile engines
Through the actual inspection and maintenance of automobile engines, it is found that common faults are mainly divided into the following categories:
3. 1 Engine knocks on the cylinder, and abnormal sound occurs inside.
Engine cylinder knocking is a common fault, which is mainly caused by the failure of crank mechanism, mainly because the accessories in crank mechanism are deformed or displaced during operation, resulting in cylinder knocking and internal abnormal noise.
3.2 The valve has air leakage and abnormal sound.
The air leakage or abnormal sound of the valve proves that the valve is not closed tightly, or the accessories of the valve system are faulty. For this kind of fault, it can be found through regular inspection and solved in advance.
3.3 Poor idle operation
The engine is idling after starting. By observing the idling state, we can know the running state of the engine well. Usually, poor idle speed is a precursor to the overall failure of the engine.
3.4 The engine cannot be started, and the acceleration is poor.
Under normal circumstances, the engine should be able to start normally and maintain continuous linear acceleration. However, due to the damage of the internal startup mechanism, it will not be able to start normally, so we must carefully check the startup system.
3.5 Abnormal oil pressure and consumption
Under normal circumstances, the engine consumes a fixed level of oil and fuel. If there is abnormal oil burning and oil consumption, it shows that the engine lubrication effect is not good and the internal mechanism is seriously worn.
3.6 The engine is overheated or supercooled, causing water leakage.
If the engine wants to run smoothly, its cylinder temperature is relatively fixed. If the engine is overheated or supercooled, accompanied by water leakage, the cylinder must be opened for maintenance in time. 3.7 The engine is difficult to start, the engine power is insufficient, and the idle speed is unstable.
If the engine is difficult to start, accompanied by unstable idle speed, and then the overall power is insufficient, it means that there is something wrong with the starting system and running system of the engine, and it is necessary to focus on the maintenance of the starting system.
3.8 There is noise and air leakage in the exhaust pipe.
When the engine is running normally, there is no noise in the exhaust pipe and the exhaust gas reaches the emission standard. If the exhaust pipe is noisy and accompanied by air leakage, it proves that the exhaust system is out of order and should be overhauled.
Analysis of typical fault maintenance scheme of automobile engine
(1) Engine cylinder knocking fault phenomenon: The main fault is that there is a strong knocking sound when the engine is idling. The knocking sound is obvious when the engine is cold-started, and gradually disappears after the engine is hot-started, and completely disappears after the engine is turned off. Fault analysis: the main reason of knocking sound is that there is a certain gap between the piston and the cylinder in the cylinder, or the piston pin and the connecting rod bushing are too tight, which eventually leads to the deformation of the connecting rod and produces the knocking sound of the cylinder.
Troubleshooting: Listen to the knocking sound with a special stethoscope for cylinder, and adjust the clearance between piston and cylinder block, or adjust the tightness of piston pin and connecting rod bushing.
(2) Abnormal sound of the piston pin: Abnormal sound of the piston pin mainly refers to the clicking sound with the increase of the engine speed at idle speed and medium speed, and the abnormal sound disappears when the engine temperature rises. After analyzing the reasons, it is found that the main reason is that the piston pin and connecting rod bushing are too loose and do not fit closely with the piston pin seat hole.
Troubleshooting: use a stethoscope to judge the sound position and properly adjust the hole distance between the piston pin and other parts.
(3) Abnormal sound of connecting rod bearing: When the engine runs smoothly, everything is normal, and there will be continuous knocking sound only during sudden acceleration. If the engine is turned off, the knocking sound will disappear. After analyzing the reasons, we can know that the main reason for this abnormal sound is that the positioning bolt of the connecting rod bearing cover is loose, which causes the wear of the connecting rod bearing and the journal, which further affects the lubrication of the bearing and eventually leads to the bearing alloy falling off.
Troubleshooting: use a stethoscope to judge the sound position, and then repair the connecting rod and accessories at this position.
(4) The occurrence of abnormal noise of main bearing: it mainly refers to the knocking sound of bearing parts when the engine accelerates rapidly. The whole engine vibrates greatly, and the abnormal noise increases with the increase of speed. The root cause is excessive wear between journal and bearing, which leads to excessive clearance, resulting in loose bolts of main bearing cover.
Fault diagnosis and elimination: directly listen to the lower half of the cylinder with a stethoscope, find out the abnormal sound position and replace the accessories.
5 conclusion
Through the analysis of this paper, we can know that in order to ensure the normal use of automobile engines and effectively prolong their life, we must carry out regular inspection and maintenance, and at the same time take active maintenance measures to detect and maintain the faults that have occurred, so as to ensure the normal use of the engines. Through the introduction of troubleshooting methods in this paper, we have a deeper understanding of the detection and maintenance of automobile engines.
References:
Liu Zhizhong. System analysis and diagnosis method of automatic transmission fault [J]. Hebei Communications Technology, 03, 2005.
[2] Weng Rongwei. Research on Expert System of Automobile Engine Fault Diagnosis [J]. Science and Technology Information, 2007, 15.
Diao Yifeng, Jintang, Liu Hongwu. Fault diagnosis and elimination method of FANUC servo system of NC machine tool [J]. Electrical technology; 10 was released in 2008.
Gou Xinchao, Tang Shiying, Tang Yong, Zhou Chuan. Fault diagnosis case of sliding bearing [J]. Metallurgical Power, 06, 2008.
Feng zhipeng. Research on the application of computational intelligence in mechanical equipment diagnosis [D]. Dalian University of Technology, 2003.
Miao Haibin, Ren. Application of peak energy spectrum technology in fault diagnosis of rolling bearings [J]. Equipment management and maintenance, 2008, May.
Click the next page for details >>& gt Technical paper on inspection and maintenance of automobile engines.