Patent ID: 7475790

Claim:
A ring-shaped gasket that is located between a pipe sealing face on an inner wall of a tank opening and a seal support element of a cap, the gasket comprising: a gasket main body that is formed in a substantially V-shaped cross section with a slit, the gasket main body being compressed to shorten a length of the gasket main body in a bending direction by narrowing the slit; and multiple sealing projections that are protruded from an outer circumference of the gasket main body, wherein the slit has a width dimension, and the gasket main body is formed so that the width dimension of the slit increases toward an opening of the gasket main body throughout the entirety of the slit, from a radially innermost position to a radially outermost position of the gasket, such that a widest part of the slit is the radially outermost part of the slit; the sealing projections include a first pipe sealing projection and a second pipe sealing projection, which come into contact with the pipe sealing face, and a first body sealing projection and a second body sealing projection, which come into contact with the seal support element, the first pipe sealing projection is formed on the opening end of the gasket main body in the bending direction and is protruded to be pressed against the pipe sealing face in an initial stage of a closing operation of the cap, the second pipe sealing projection is protruded such that the second pipe sealing projection avoids contact with the pipe sealing face in the initial stage and is protruded to have a greater sealing face pressure than the first pipe sealing projection when the gasket is compressed against the pipe sealing face after the initial stage of the closing operation, and the first body sealing projection and the second body sealing projection are formed on a surface of the gasket main body to face the seal support element and are arranged to form triangles with the first pipe sealing projection and with the second pipe sealing projection respectively.