Active Contact Problems in Epitrochoid Generated ‘Floating Axis’ Orbital Rotary Piston Machines

The patterns of contact stresses and rolling-sliding motions at the active contacts of the rotary piston machine (ROPIMA) type hydrostatic units, having “epitrochoid” generated rotor-stator set with epicyclic motion of the “floating axis” rotor, have been investigated. A dimensionless analytical technique, based on Hertz’s contact theory, has been developed. As the stress problem in such machines is a statically indeterminate type a numerical iterative scheme has been adopted for solutions. It is found that the gaps are generated even at the “transition contacts”. Effects of profile modifications on these constraints have been studied. Some results have also been supported experimentally. Optimum values of modifications have also been suggested in most generalized form.