Automatic closing pressure relief device

The utility model relates to an automatic closing pressure relief device which comprises a valve body, a main piston and an auxiliary piston, the valve body is a cross-shaped hollow cavity and comprises an upper cavity body, a lower cavity body, a left cavity body and a right cavity body which are communicated with one another, and a branch pipe communicated with the left cavity body and the right cavity body is arranged on the valve body; the main piston is arranged to play a sealing role, when pressure in the pressure channel is overloaded, air pressure impacts the main piston, the lower cavity is opened, then the air pressure impacts and compresses the auxiliary piston along the left cavity and the right cavity, the left cavity, the right cavity, the branch pipe and the branch pipe are directly communicated with the outside, and therefore pressure relief is completed instantly, and after pressure relief, the pressure in the cavities is rapidly reduced; the first spring and the second spring drive the main