Automotive air filter is mainly responsible for the removal of particulate impurities in the air device. When the piston machinery (internal combustion engine, reciprocating compressor, etc.) works, if the impurities such as dust are inhaled into the air, it will aggravate the wear of the parts, so the air filter must be installed. The air filter is composed of a filter core and a shell. The main requirements of air filters are high filtration efficiency, low flow resistance, long continuous use without maintenance.