Piston cylinder sealing structure, brake cylinder and brake clamp unit

The utility model relates to a piston cylinder sealing structure, a brake cylinder and a brake clamp unit, the piston cylinder sealing structure is assembled between a cylinder body and a piston of a piston cylinder, and comprises a piston sleeve, a first sealing ring and a second sealing ring; the piston sleeve is fixedly installed in the cylinder body and covers the piston, an air chamber is formed between the piston sleeve and the piston, and a ventilation hole communicated with the air chamber is formed in the circumferential side wall of the piston sleeve; the first sealing ring is sealed between the outer edge of the piston and the circumferential inner wall of the piston sleeve; and the second sealing ring is sealed between the circumferential outer wall of the piston sleeve and the circumferential inner wall of the cylinder body, so that a sealing airflow channel used for communicating the ventilation hole with an air charging and discharging opening formed in the circumferential side wall of the cyli