The engine is composed of two mechanisms and five systems. The so-called cast iron engine and aluminum alloy engine only refer to the material of the engine cylinder block. As for the material of other parts, they are basically the same. In other words, aluminum alloy engines also have many iron parts, and cast iron engines also have many aluminum alloy parts. In order to explain the material of the automobile engine in detail, we might as well break down the engine and explain the material of each component in detail.
1. Cylinder block: The cylinder block is the most basic part of the engine, and other various parts are directly or indirectly installed on it.
The cylinder block is made of two kinds of materials. One is cast iron, which is generally cast with gray iron. In order to enhance the strength and wear resistance of the cylinder block, the current engine also uses high-quality gray iron containing nickel, chromium, molybdenum, phosphorus and other elements. Some highly strengthened diesel engines are cast with higher grade nodular cast iron or vermicular cast iron. The strength, stiffness, wear resistance and vibration absorption capacity of cast iron cylinder block are excellent. The biggest disadvantage is that it is heavy.
Now, the gasoline engine used in small cars is mostly made of aluminum alloy cylinder block or aluminum magnesium alloy cylinder block. They are made of aluminum alloy or aluminum magnesium alloy. The greatest advantages are light weight and good heat dissipation. However, the strength, stiffness, wear resistance and vibration absorption capacity of the cylinder block are not as good as those of the cast iron cylinder block. Therefore, those who boast that aluminum alloy engines are better can rest.
2. Cylinder head: The working conditions and structural complexity of the cylinder head and cylinder block have much in common, so they are generally cast with the same material, which is also gray cast iron or alloy cast iron. In order to improve the heat dissipation performance and reduce the engine weight, some gasoline engines will use aluminum alloy to cast the cylinder head. However, aluminum alloy has low strength and is easy to deform in use, so it can only be used in gasoline engines. Diesel engines are still cast with higher strength cast iron.
3. Cylinder liner: The cylinder liner is embedded on the cylinder block, and the piston and piston ring move up and down in it, so it must be very wear-resistant. Therefore, it is generally made of high-grade cast iron with good wear resistance, such as pearlitic cast iron, alloy cast iron, high phosphorus cast iron, boron containing cast iron, etc. It should be noted that cylinder liners of both cast iron engines and aluminum alloy engines are cast iron, and aluminum alloy engines must also be embedded with a cast iron cylinder liner. Now there is a more advanced technology, which is to directly use metal spraying technology on the aluminum alloy cylinder block, spray a layer of dense wear-resistant iron coating, and then use laser quenching to enhance the hardness and wear resistance, which can greatly reduce the weight and volume of the engine. However, such an engine cannot be repaired. If there is a cylinder blowout, the engine can only be replaced directly.