The importance of the filtration performance of automotive air filters

The performance of automotive air filters is related to the structure of the air filter itself on the one hand, and the key to the processing quality of the filter material and filter element used on the other hand.

The requirements for the filter material of the air cleaner are, first of all, good "breathability" to ensure the low resistance of the filter element, and secondly, the porosity is appropriate to ensure a sufficiently high filtration efficiency and filtration accuracy. These two requirements are contradictory. Reducing the pore size of the filter material can improve the filtration efficiency, but the resistance of the gas passage must be increased, which requires different filter materials to meet the needs of different requirements of the air filter.

The requirements for the air filter are: Must be able to filter out the dust particles in the road dust that are the most serious wear on the engine cylinder piston ring. In the particle size distribution of road dust, 50% of the particles have a size of 10-30um. The basic components of dust are: silica or quartz (SiO2), alumina (Al2O3, iron oxide (Fe2O3), and a small amount of compounds of calcium, magnesium, sodium, and other elements. Lime accounts for the largest proportion of dust, about Accounted for 65-95%.

The size of dust particles has an important effect on wear. When the particle size increases from 3~5um to 15~30um, the piston ring wear increases by 1~3 times. The size of dust particles continues to increase, and piston ring wear decreases. This can be explained by the assumption of the "filtering effect" of the gap between the piston ring and the cylinder, that is, particles whose size exceeds the gap cannot enter the gap and therefore cannot play a role in wear.

Studies at home and abroad have shown that 10~40um particles have the most serious wear on the cylinder. 10~40um particles account for 60% of the dust, so the air filter must be able to filter out this part of the particles.