Analysis of Automobile Engine Maintenance Technology

As the heart of the automobile, the engine plays a vital role in the normal operation and operation of the automobile. Therefore, it is necessary to strengthen the repair and maintenance of the engine at ordinary times. For the maintenance of automobile generators, it needs comprehensive technical knowledge and practical operation ability. Therefore, the maintenance of automobile engine can be said to be a hard job that requires skill and technology. In this paper, the related maintenance technologies are elaborated in detail from two aspects: automobile engine inspection, automobile engine diagnosis and maintenance, hoping to be helpful to those who study automobile engine maintenance.

keywords automobile; Engine; Maintenance; Technology

Chinese picture classification number U46 document identification number A article number 1674-678(214)114-19-2

1 Traditional engine maintenance technology

Inspection of internal parts of the engine:

Because the crankshaft and piston inside the automobile engine are often prone to failure, such as the sudden failure of the automobile, it is probably because of the automobile engine. Therefore, when an automobile engine fails and needs maintenance, the crankshaft and piston can be inspected first, and the specific steps are as follows:

1.1 Inspection of the crankshaft

For the faults that are easy to occur in the crankshaft, the journal is easy to wear, and it is prone to distortion or fatigue cracks, so it is necessary to carry out key inspections. 1) Crack inspection: For crankshaft crack inspection, the corresponding inspection methods include ultrasonic flaw detection, oil immersion tapping, magnetic flaw detection and X-ray flaw detection. When the crankshaft is inspected by oil immersion tapping method, it is necessary to soak the crankshaft in kerosene for a period of time, then take the crankshaft out of kerosene, clean it, sprinkle some white powder on the crankshaft, and then tap on different parts of the crankshaft. If there are obvious oil stains, this shows that there are cracks in this part of the crankshaft. For the magnetic flaw detector inspection, its magnetic field lines will penetrate the inspected part of the crankshaft. If there is a crack in this part, the magnetic field lines in this part will diverge, and then the magnetic powder will be scattered on this part, which will show the specific size and location of the crack. 2) Inspection of bending deformation: For the inspection of bending deformation of the crankshaft, the two top ends of the whole crankshaft can be supported by V-shaped blocks, as shown in Figure 1, and then used in the middle of the spindle to be abutted by the contact of a dial indicator. When the crankshaft rotates once, find out the minimum and maximum angles on the pointer, and calculate the difference between them. This difference is the difference of crankshaft bending deformation. If it is greater than .11mm, the crankshaft is seriously bent. In order to ensure the normal operation of the engine, it is necessary to replace the crankshaft in time.

1.2 inspection of piston connecting rod group.

the inspection of the corresponding piston position is mainly to check whether the size of the piston pin seat and the diameter of the skirt have changed, or whether it is blocked during use. There are generally two main inspection methods. The first inspection method is to measure with a micrometer. By measuring the diameter of the skirt and the value of the worn part of the piston cylinder, these two measured data are subtracted, and then compared with the cylinder clearance value. If the difference is greater than .1mm, it means that the piston is seriously worn and cannot be used again. Another method is to measure with a feeler gauge, and judge whether the piston in the automobile engine can be used normally by measuring the cylinder clearance. First, put the feeler gauge into the ring groove where the gas ring is installed, and then gently rotate the feeler gauge with a pulling force of 35N, and stop rotating when slight resistance is felt, so that the difference between the skirt of the piston and the side clearance of the piston can be measured with the feeler gauge. The more the piston is worn, the greater the corresponding difference is. When the value exceeds .12mm, the piston can no longer be used, and a new piston needs to be equipped for the automobile engine. As shown in figure 2.

Figure 2 Figure 3 Figure 4

2 Diagnosis and maintenance of automobile generators

2.1 Engine stall fault

If there is a stall fault in the engine, it generally shows that the engine speed will be lower and higher, and this situation is a common engine stall fault. The main reason for this failure is that the ignition control system is out of order, or the fuel nozzle system is out of order, or the air intake system of the whole engine is out of order. For example, there is a fault in the fuel nozzle system, which is likely to be unstable line contact, tubing deformation or too many ash layers in the fuel filter. For different reasons, different measures can be taken for maintenance.

The related troubleshooting and maintenance methods are as follows: 1) If there is a problem with the fuel injection system, check whether it is a poor line contact; if so, you can adjust the line or replace the lead for maintenance; if there are too many ash layers such as the oil filter cover, you can repair it by cleaning the filter cover; 2) If there is a problem with the air inlet pipe, carefully check whether there is air leakage in each hose or its connected place, or check whether the PVC valve pipe is ventilated normally. If not, consider repairing or replacing the corresponding pipe; 3) In view of the problems in the ignition control system, it is necessary to check whether the spark plugs of each cylinder are working normally. For example, the spark plug accumulates too much ash layer, which causes the engine speed to be abnormal, so it can be repaired by thoroughly cleaning the spark plug.

2.2 poor engine idle fault

the phenomenon of poor engine idle fault is mainly that the engine idle is unstable and it is easy to stall when parking. In the aspect of fault diagnosis, the engine fuel pressure can be detected first. Connect the fuel pressure gauge to the oil pressure detection hole, start the engine, the oil pressure gauge indicates that the pressure is normal, and the pressure is 265kPa. Remove the vacuum tube of the oil pressure regulator, and the oil pressure rises to 34kPa. The above results are within the standard range, indicating that the fuel pipeline system is fault-free. Then check the cylinder pressure. Preheat the engine to 85℃, open the throttle valve, and measure the pressure of each cylinder with a cylinder pressure gauge. When the pressure values are all about l1OOkPa and the pressure difference of each cylinder is 3kPa, the above situation indicates that there is a problem with the sealing performance of the engine cylinder.

for the maintenance of this fault, the methods are as follows: clean the idle motor and throttle body. Remove the idle motor and throttle body, thoroughly clean all air passages and blow them clean with compressed air. Measure the resistance of idle motor with multimeter. The resistance is 2Ω, which is within the normal range of 18 ~ 24Ω. When measuring the throttle position sensor, the output resistance changes linearly and is within the normal range. If any foreign matter is found in the intake manifold, clean it up with iron wire wrapped with linen. In order to completely eradicate the fault, the injector can also be cleaned and tested.

3 Conclusion

As can be seen from the above analysis, this paper simply introduces the common faults of automobile engines, their causes and solutions. In fact, the maintenance coverage of the whole automobile engine is relatively wide, and its corresponding maintenance technology is also relatively comprehensive and complicated. To master the maintenance skills and related technologies of automobile engines skillfully, we still need to learn and practice a lot of knowledge, such as the inspection and maintenance of electronically controlled fuel system, so I won't go into details here.

References

[1] Zhu Yingwen, Wei Hao, Zhang Qin. Exploring the maintenance and detection technology of automobile generators [J]. Automobile and Technology, 24 (1): 235-248.

[2] _ _ Bin, Luo Luo. Some thoughts on the maintenance technology of automobile generators [J]. 27 (2): 129-137.

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