Patent ID: 7427171

Claim:
A pressure vessel comprising: a pair of members made of different materials and fitted together, said pair of members including: a first one of said pair of members defining an outer cylinder of the pressure vessel and having a joining face; and a cup-shaped second one of said pair of members having a closed end and a joining face; wherein said first one of said pair of members is made of a plastically deformable metal material; wherein said second one of said pair of members is made of a material having a greater hardness than said plastically deformable metal material of said first one of said pair of members, said second one of said pair of members having an annular protrusion on an axial end surface portion of said joining face of said second one of said pair of members, and having an annular groove on an outer circumferential surface portion of said joining face of said second one of said pair of members; wherein said pair of members are fitted together such that: said annular protrusion of said second one of said pair of members bites into said joining face of said first one of said pair of members so as to be held by elastic deformation pressure of said first one of said pair of members; and said plastically deformable metal material of said first one of said pair of members extends into said annular groove of said second one of said pair of members so as to hold said second one of said pair of members by the elastic deformation pressure.