During maintenance, the paper filter element must not be cleaned in oil, otherwise the paper filter element will fail, and it is easy to cause a speeding accident. During maintenance, only the vibration method, the soft brush removal method (to brush along the wrinkle) or the compressed air blowback method can only be used to remove the dust and dirt attached to the surface of the paper filter element. For the coarse filter part, the dust in the dust collecting part, the blades and the cyclone pipe should be removed in time. Even if it can be carefully maintained every time, the paper filter element cannot fully restore its original performance, and its air intake resistance will increase. Therefore, generally, when the paper filter element needs to be maintained for the fourth time, it should be replaced with a new filter element. If the paper filter element is cracked, perforated, or the filter paper and end cap are debonded, it should be replaced immediately