Seal structure of high-pressure tank

A seal structure of a high-pressure tank that seals a space between a first member having a cylindrical shape and a second member, the high-pressure tank including:

• the first member in which an opening hole is provided at an end part in the axial direction and a tank chamber is formed inside;
• and the second member which is fitted into the opening hole of the first member and provided with an annular groove formed on an outer peripheral surface, the seal structure comprising:
• a seal member, having an annular shape, configured to be disposed on the tank chamber side in the groove and to be moved by being pressed in the axial direction opposite to the tank chamber side by the pressure of the tank chamber;
• and
• a first back-up member and a second back-up member configured to be disposed further to the side opposite to the tank chamber side than the seal member in the groove, to include inclined surface parts respectively opposite to each other, and to be deformed so that the whole width in the radial direction becomes large by sliding therebetween which is caused by being pressed from the seal member moved by the pressure of the tank chamber in a state where the inclined surface parts abut on each other, wherein
• the inclined surface part of the first back-up member includes:
• a first low angle inclined part configured to be inclined at a predetermined angle with respect to the axial direction of the first member;
• a first high angle inclined part configured to be inclined at an angle larger than the predetermined angle with respect to the axial direction of the first member, and to generate abutting later than abutting timing at the first low angle inclined part at the time of the pressure from the seal member;
• and
• a crest folding corner part in which the first low angle inclined part and the first high angle inclined part are connected to each other.