This paper describes the design, optimization and the performance potentials of external gear machines with asymmetric tooth profiles. Conventionally, the design of these machines is entirely based on symmetric involute profile. A design method has been developed to derive the tooth profiles based on a modified rack-cutter profile which is assumed to be used for manufacturing the gears with asymmetric involute surfaces and trochoidal fillet profiles.
The study is based on the simulation tool HYGESim (HYdraulic GEar machines Simulator) which is being developed and has been validated by the authors’ research group to accurately analyze the performance of the machine. For the purpose of this research, HYGESim was adapted to simulate the particular case of non-symmetric gear profiles.
A specific optimization procedure based on genetic algorithm was implemented to find the maximum performance of the new design, in terms of volumetric efficiency, fluid borne noise, internal pressure peaks and localized cavitation acting on the design parameters that characterize the tooth profile.
The results of the optimization process are compared to the current state of the art for external gear machines. This comparison show very high potentials for this new design principle, particularly concerning the reduction of the fluid borne noise.