High-pressure hydrogen tank

A high-pressure hydrogen tank comprising:

• a metal circular cylinder configured to store high-pressure hydrogen therein;
• a cap part configured to cover each of opposite end portions of the metal circular cylinder;
• a hollow outer part surrounding an outer periphery of a circular-cylindrical portion of the metal circular cylinder;
• and
• a fastening part configured to fix the cap part to the hollow outer part,
• wherein the metal circular cylinder is made of a material selected from the group consisting of chrome molybdenum steel, nickel-chrome molybdenum steel, manganese chrome steel, manganese steel, and boron steel,
• on an inner peripheral surface of the metal circular cylinder, a decarburized layer has been removed,
• the cap part includes a leaked-hydrogen discharge hole passing through an outside of the cap part at a position facing an end surface of the metal circular cylinder,
• a hydrogen sensor configured to monitor a leakage of hydrogen is provided at an exit of the leaked-hydrogen discharge hole,
• the high-pressure hydrogen tank has a first fitting structure configured to fit the metal circular cylinder and the cap part to each other, the fitting structure comprising projecting portions formed on each opposite end surface of the metal circular cylinder, and corresponding recessed portions formed on each opposite end surface of the cap part, the projecting portions projecting in an axial direction of the high-pressure hydrogen tank from the metal circular cylinder into the respective corresponding recessed portions to prevent movement of the metal circular cylinder relative to the hollow outer part in a thickness direction of the high-pressure hydrogen tank orthogonal to the axial direction, and
• a sealing part is provided between the metal circular cylinder and the cap part on an inner-diameter side relative to the first fitting structure, the sealing part being located at axial end faces of the metal circular cylinder.