Compared with the traditional core components of automobile engines, engine high-pressure fuel pipes have not received special attention for a long time. However, statistics show that in recent years, the failure cases of high-pressure fuel pipes have been increasing, and their proportion has also entered automobiles year after year. The number of engine parts failures in the top ten, and there is an increasing trend.

The engine high-pressure fuel pipe is an important part connecting the fuel injection pump and the fuel injector, and it undertakes the task of delivering high-pressure fuel to the engine. Once the high-pressure fuel pipe of the engine cracks, causing oil leakage, it will not only adversely affect the reliability of the whole engine, but also, after the high-pressure fuel injection leaks, it is very likely to come into contact with the high-temperature components of the engine, resulting in a serious fire accident.

Therefore, it is of urgent practical significance to analyze and summarize various failure modes of high-pressure oil pipes in the current market.

Internal surface defects of raw materials for high-pressure oil pipes

During the manufacturing process of high-pressure oil pipe, its inner surface has undergone a complex drawing deformation process, and various degrees of inner wall defects will inevitably be formed in this process, the most important of which is the inner wall crack defect.

Poor machining quality at the transition between heading and stem

The machining process of the high-pressure oil pipe heading is complicated and the deformation is large. The metal on the inner and outer surfaces undergoes strong deformation and flow. If the process is improper, the metal streamline may be twisted or even cold folded. Figure 3 shows the cold folded shape found by metallographic inspection of the inner and outer surfaces of a high-pressure oil tube heading.

Various process defects at the upsetting head will become the origin of fatigue cracks during use, resulting in oil pipe cracking and oil leakage. Therefore, each enterprise will control the defect form in its internal standards, mainly for the upsetting head. The depth of the cold folded crack is controlled.