The engine needs to suck in a large amount of air during the working process. If the air is not filtered, the dust suspended in the air is sucked into the cylinder, which will accelerate the wear of the piston group and the cylinder. Larger particles enter between the piston and the cylinder, causing a serious "cylinder" phenomenon, which is especially severe in dry and sandy working environments. The air filter is installed in front of the carburetor or the intake pipe to filter out dust and sand in the air to ensure sufficient and clean air in the cylinder.