US Patent 10107401 Sealing structure

A sealing structure suppresses possible damage to a seal ring because of a backup ring. The sealing structure is characterized in that a cut portion 150 that is cut in a planar shape is formed in a backup ring 100 at one position in a circumferential direction, the cut portion 150 is configured such that a cut surface 153 is oblique to a central axis of the backup ring 100, an acute angle of angles between a surface on the high pressure side of the backup ring 100 and the cut surface 153 is set to not less than 15° and not more than 30°, and the backup ring 100 is formed of a resin material having Rockwell hardness of 100 or less, durometer hardness of 70 or less, and elastic modulus of 1.0 GPa or less.