Patent ID: 7226279

Claim:
A gerotor mechanism for a screw hydraulic machine, said gerotor mechanism comprising a stator having inner helical teeth made of a elastoplastic material, and a rotor having outer helical teeth whose number by one tooth is less than that of the stator, leads of screw lines in the stator and the rotor being proportional to numbers of their teeth, a rotor axis being shifted with respect to a stator axis by an eccentricity value equal to half of the rotor/stator teeth radial height; wherein profiles of the rotor and/or stator are outlined in end cross section thereof in the form of an envelop of an initial contour of a rack-type tool, which contour is formed by conjugation of circle arcs when said initial contour of the rack-type tool is run without sliding along corresponding toll circles, and radii of the circle arcs of the initial contour being calculated according to the following expressions: r i =K [(π 2 r w1 2 /4 Ez 1 2 ) +E ]/( K +1) or r i =K [(π 2 r w2 2 /4 Ez 2 2 ) +E ]/( K +1), r c =r i /K , where r i is an initial radius of the rack-type tool profile, K=(0.5 . . . 2) is a shape coefficient of the initial contour, r w1 , r w2 are radii of tool circles of the rotor and the stator, respectively; E is eccentricity of meshing, z 1 , z 2 are numbers of teeth of the stator and the rotor, respectively; r c is conjugated radius of the rack-type tool profile.