Abstract: A lip seal includes: a lip part (1) forming a ring shape alone or with plural members and provided in sliding contact with the entire periphery of a surface of a shaft (0); an elastic arm part (2) and a flexible wall (3) supporting the lip part (1) at a sliding contact position; key parts (4) connecting the elastic arm part (2) and the flexible wall (3) to a housing (10), respectively, and a pressure regulation chamber (A) forming a ring shape alone or with plural members and using the elastic arm part (2) and the flexible wall (3) as partition walls. The flexible wall (3) is deformed by the increase and decrease in pressure in the pressure regulation chamber (A) to change the lip part (1) at least radially.

Abstract: A sealing device includes: a sealing ring (1) slidably in hermetic contact with a surface of a shaft (A); a hollow partition wall (2) in contact with the sealing ring (1); and a housing (B) holding the sealing ring (1) and supporting the hollow partition wall (2). The sealing ring (1) is formed of an elastic material, and includes a lip part (1a) in sliding contact with the entire periphery of the surface of the shaft (A), an elastic arm part (1b) supporting the lip part (1a) at a sliding contact position, and a key part (1c) connecting the elastic arm part (1b) and the housing (B). The straining force on the shaft (A) is adjusted by expansion and contraction of the hollow partition wall (2).

Abstract: A lip seal includes: a lip part (1) forming a ring shape alone or with plural members and provided in sliding contact with the entire periphery of a surface of a shaft (0); an elastic arm part (2) and a flexible wall (3) supporting the lip part (1) at a sliding contact position; key parts (4) connecting the elastic arm part (2) and the flexible wall (3) to a housing (10), respectively, and a pressure regulation chamber (A) forming a ring shape alone or with plural members and using the elastic arm part (2) and the flexible wall (3) as partition walls. The flexible wall (3) is deformed by the increase and decrease in pressure in the pressure regulation chamber (A) to change the lip part (1) at least radially.