Information dynamics
The key process of cylinder liner-free technology for automobile engine block | coating honing
The technology of automobile engine without cylinder liner originated in Europe, which uses thermal spraying technology to spray a wear-resistant coating on the inner wall of aluminum engine cylinder to replace the traditional cast iron cylinder liner, which can not only reduce the weight and fuel consumption of the engine, but also significantly reduce the engine friction and improve the engine performance.
After the cylinder body is sprayed, the machining of the coating is very important, and the coating must be honed, so that the cylinder can reach the specified correct diameter, roundness and surface roughness. A well-known thermal spraying company in Europe has made fine adjustments to the recommended technical specifications of the honed coating surface according to the results of reducing oil consumption and fuel consumption obtained from engine tests, as shown in the following table. It is very important to clean the surface of the coating properly after honing, so that there will be no debris left in the pores. The burr should be cleaned at the edge of the hole, and the honed surface should be free of scale.
After rough honing and fine honing, the inner surface of the cylinder hole can reach the mirror surface, as shown in Figure 2. Compared with the traditional honing of cast iron cylinder liners, the surface after coating honing has a porous structure, rather than a reticulated structure. Fig. 3a shows the surface microstructure of traditional cast iron cylinder liners after honing, and Fig. 3b shows the microstructure after coating honing.
It is precisely because of the porous structure of the coating surface that the smoothness of the coating surface can be reduced to 25%, which is one of the reasons why this technology can save a lot of engine oil. Smooth and round holes also reduce the area of oil exposed to the combustion chamber and piston ring, reduce the tangential force of the oil scraper ring, make the piston ring enter the hydrodynamic state faster, and significantly reduce the friction force. The working schematic diagram is shown in Figure 4. Smaller engine friction means lower energy consumption of friction heat generation, reducing engine blowby and fuel consumption. (Blow-by refers to the internal gas of the engine "channeling" from the piston ring gap to the crankcase after the cylinder and piston are worn or deformed, which affects the engine power and fuel consumption. Due to the inherent porosity of the coating, the oil storage structure will not be worn away like the reticulated structure, but will open new pores with the development of wear to the coating, so its life-cycle efficiency will be significantly improved.
The benefits of cylinder hole spraying not only reduce friction and oil consumption, but also improve the wear resistance and corrosion resistance of cylinder hole surface. Because the oxides contained in the coating are iron oxide (FeO) and magnet (Fe3O4), these are well-known solid lubricating materials, which can further improve the wear resistance.
Thermal spraying technology can be used to spray not only on the new cylinder, but also on the worn cylinder to restore it to its original size, thus avoiding the problem of using large piston and piston ring. In addition, it is also suitable for spraying cylinder liners and motorcycle cylinders.
After the cylinder body is sprayed, the machining of the coating is very important, and the coating must be honed, so that the cylinder can reach the specified correct diameter, roundness and surface roughness. A well-known thermal spraying company in Europe has made fine adjustments to the recommended technical specifications of the honed coating surface according to the results of reducing oil consumption and fuel consumption obtained from engine tests, as shown in the following table. It is very important to clean the surface of the coating properly after honing, so that there will be no debris left in the pores. The burr should be cleaned at the edge of the hole, and the honed surface should be free of scale.
After rough honing and fine honing, the inner surface of the cylinder hole can reach the mirror surface, as shown in Figure 2. Compared with the traditional honing of cast iron cylinder liners, the surface after coating honing has a porous structure, rather than a reticulated structure. Fig. 3a shows the surface microstructure of traditional cast iron cylinder liners after honing, and Fig. 3b shows the microstructure after coating honing.
It is precisely because of the porous structure of the coating surface that the smoothness of the coating surface can be reduced to 25%, which is one of the reasons why this technology can save a lot of engine oil. Smooth and round holes also reduce the area of oil exposed to the combustion chamber and piston ring, reduce the tangential force of the oil scraper ring, make the piston ring enter the hydrodynamic state faster, and significantly reduce the friction force. The working schematic diagram is shown in Figure 4. Smaller engine friction means lower energy consumption of friction heat generation, reducing engine blowby and fuel consumption. (Blow-by refers to the internal gas of the engine "channeling" from the piston ring gap to the crankcase after the cylinder and piston are worn or deformed, which affects the engine power and fuel consumption. Due to the inherent porosity of the coating, the oil storage structure will not be worn away like the reticulated structure, but will open new pores with the development of wear to the coating, so its life-cycle efficiency will be significantly improved.
The benefits of cylinder hole spraying not only reduce friction and oil consumption, but also improve the wear resistance and corrosion resistance of cylinder hole surface. Because the oxides contained in the coating are iron oxide (FeO) and magnet (Fe3O4), these are well-known solid lubricating materials, which can further improve the wear resistance.
Thermal spraying technology can be used to spray not only on the new cylinder, but also on the worn cylinder to restore it to its original size, thus avoiding the problem of using large piston and piston ring. In addition, it is also suitable for spraying cylinder liners and motorcycle cylinders.