Theoretical Analysis of Internal Lobe Pumps

In this work a theoretical study of the performance of internal epitrochoidal pumps, as a function of the geometrical parameters, is achieved. The machines considered are constituted by two rotors: one rotor has an epitrochoidal profile, and the other rotor is shaped by arcs of circumference and by a limit profile. In this paper the construction of the profiles is performed by the theory of gearing, in order to calculate some selected performance indexes. By choosing three non-dimensional parameters, all the possible geometries of this type of pumps can be examined: in particular, the used approach permits to consider the pump type with epitrochoidal outer rotor too. Finally, a general analysis of the calculated performance and operational indexes is presented