The Design And Application Research On A Gerotor Oil Pump With Variable Semimajor Axis Ellipse-like Profile

As an important part of the automotive and engineering machinery,oil pumps get a great progress as the automotive and engineering machinery industry.With the increasing of the performances on the fluid,wear and noise,the gerotor pump with the generic ellipse tooth profile can’t meet the requirement of the performances.One of the key factors influencing these performances is the tooth profile of the rotor.The tooth profiles of the inner rotor and the outer rotor not only decide the smoothness and continuity of the mesh process,but the chamber volume and the clearance between the rotors also decide the flow characteristic.Thus,the research on the tooth profiles of the rotors in the oil pump is very important to the performance improvements.Meanwhile,in order to minimize the cost of the development and modification,the new developed tooth profile should share the same basic design parameters of the generic ellipse tooth profile.This article is based the project of Noise Control Mechanism of Rotor Oil Pump Based on Sound-Vibration Coupling(12JJ9015)funded by Hunan Natural Science Funds.And a new ellipse-like tooth profile with varying semi axes of the rotor and the correction of the profile have been developed.The performances on the flow,wear,cavitation and noise have been simulated,and the related experiments have also been carried out.The main innovations and research works of this paper are as follows:(1)First,replace the constant lengths of the semi-major and semi-minor axes of an ellipse with the variables related to the angle t.Then,the meshing boundary angle t_f of the outer rotor,the corresponding angle t_d of the point of tangency of the chamber arc and the theoretical tooth profile of the outer rotor,and some other angles are calculated by using secondary envelope method and Matlab.Based on the above content,the theoretical tooth profile of the outer rotor has been gotten.Next,as the conjugate curve of the theoretical tooth profile of the outer rotor,the theoretical tooth profile of the inner rotor has also been gotten by using coordinates transformation matrix.Finally,the design method of the new ellipse-like tooth profile with varying semi axes has been developed.(2)Considering the specific sliding and the transmission characteristic of the theoretical tooth profiles of the rotors,a correction on the theoretical ellipse-like tooth profile of the inner rotor has been carried out by combing correction methods of equidistance and rotated angle.(3)The fluid simulation and experiment of the gerotor oil pump with ellipse-like tooth profile have been carried out.The simulation results meet the experimental ones well.Based on the results,the performances on the flow rate,fluid moment,pressure ripple and cavitation of the gerotor oil pump with ellipse-like tooth profile have been researched and analyzed.(4)The noise simulation and experiment of the gerotor oil pump with ellipse-like tooth profile have been carried out.The results show that the noise performance of the gerotor oil pump with ellipse-like tooth profile is better than that of the gerotor oil pump the ellipse tooth profile...