Scroll-type fluid displacement apparatus with cup shaped casing

Claim 1

In a scroll-type fluid displacement apparatus including a housing having a front end plate member with an end surface, a fixed scroll member fixedly disposed within said housing and having a first circular end plate from which a first wrap extends, an orbiting scroll member having a second end plate from which a second wrap extends and said first and second wraps interfitting at an angular offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets, and a driving means including a drive shaft which penetrates said front end plate member and is rotatably supported thereby for effecting the orbital motion of said orbiting scroll member by the rotation of said drive shaft while the rotation of said orbiting scroll member is prevented, whereby said fluid pockets change volume by the orbital motion of said orbiting scroll member, the improvement comprising said housing comprises a cup shaped casing with an inner cylindrical surface and said front end plate member having an annular the improvement comprising said housing comprises a cup shaped casing with an inner cylindrical surface and said front end plate member having an annular projection extending from said end surface thereof and facing an opening in said cup shaped casing, said cup shaped casing being received about said first and second end plates and said annular projection with its inner surface in fitting engagement about the peripheral surface of said first circular end plate and the peripheral surface of said annular projection, and said fixed scroll member fixedly held within the interior of said cup shaped casing by a plurality of screw members screwed from the outside of said cup shaped casing into a fixed member formed integral with said end plate and which is disposed between the end surface of said first end plate which is opposite to the side thereof from which said first wrap extends and the inner surface of said cup shaped casing.