Kinematic analysis of gerotor type pumps, engines, and compressors

Rotary volume displacing mechanisms are widely used as oil pumps, air compressors, and the Wankel rotary engine. Although some of these mechanisms appear to be widely different they are of the family of gerotors and have the same basic mathematical shape generation relationships. Rotary volume displacing mechanisms classified as gerotors have lobes or teeth on the two working surfaces with all lobes in continuous contact. The number of lobes on the working surfaces differ by one, e.g. the Wankel rotary engine has three lobes on the rotor and two lobes on the housing. The result of this study is the presentation of the analytical methods for determining the maximum theoretical flow rate and compression ratio for a given gerotor. The study covered the effect of the number of lobes on the generating gear, radius of the generating arc, gear on which the generating arc is located and the r$\sb{\rm p}$/r$\sb2$ ratio (where r$\sb{\rm p}$/r$\sb2$ = the distance from the center of the generating arc to the center of the gear to which it is attached divided by the radius of the larger pitch circle), in relationship to the maximum theoretical flow rate and compression ratio. It is hoped that this work will contribute to the advancement of gerotor design and will encourage others to continue the work. The author also hopes the invention and presentation of the Doublerotor will stimulate designers in their use of gerotors