Patent ID: 7520738

Claim:
A displacement machine comprising: two profiled members, inner and outer respectively, that have an annular inner profile and an annular outer profile, a connecting member with respect to which each of the profiled members is rotatably supported about a respective axis of rotation (O, O′; O′, O), and in which: one of the profiles is m-lobed and the other is (m−1)-lobed, and they are defined around the axis of rotation of their respective profiled member by m and (m−1) lobes respectively, wherein each lobe of the profile of each profiled member comprises a lobe dome arc and a lobe hollow arc, each profile is the envelope of the other during relative rotations of the profiled members around their respective axis of rotation with meshing of their profiles, which define the chamber contours between them, and rolling without sliding between two pitch circles centred on the respective axes of rotation, wherein relative positions of the profiled members for which a contact point (C 2 ) between the profiles is located on the tangent to the two pitch circles at their mutual rolling point, the profiled members have at said point of contact equal continuous curvatures in the same direction with said rolling point (R) as their common centre.