Air filter with flexible installation structure

The utility model discloses an air filter with a flexible mounting structure, which comprises a rough filtration shell, a rough filter is arranged in the internal space of the rough filtration shell, the downstream end of the rough filtration shell is connected with a middle shell, and a main filter element is arranged in the middle shell; the downstream end of the middle shell is connected with an air outlet end cover, an air outlet is formed in the air outlet end cover, a first dust discharging hole communicated with the inner space of the rough filtration shell is formed in the middle of the circumferential surface of the rough filtration shell, a second dust discharging hole is formed in the bottom of the circumferential surface of the rough filtration shell, and a dust discharging valve is assembled at the first dust discharging hole or the second dust discharging hole. And a blanking cap covers the second dust discharge hole or the first dust discharge hole. Bolt holes used for being connected with a fi