| Large displacement and high volume utilization rate is an important development direction of gear pump.Elliptic gear pump with high order elliptic gear as the rotor,whose displacement can be improved by 4~6 times compared with the normal gear pump,in the field of fluid transport shows great potential applications.But the severe instantaneous flow pulsation seriously restricts its application,so the suppression of flow pulsation has become the core problem of elliptical gear pump research.With detailed analysis of the high order elliptical gear pump working principle,the instantaneous flow model is established with considering the influence of tooth mesh.With discussing the rotor eccentricity,modulus and order number,it is found that rotor eccentricity is the root of the serious flow pulsation.According to the law of flow pulsation,an approach is put forward to reduce the pulsation by driving the elliptical gear pump with external non-circular gear.The curve equation of non-circular gear is calculated with the instantaneous flow is equal to the average flow,and the closed condition is proved through the residue theorem.The internal incentive is revealed by studying transmission system of the pump.Establishing dynamic model of two levels of non-circular gear with considering the stiffness,damping and instantaneous center,the multiple frequency response characteristic of the pump is found by solving the dynamic response,and the influence laws of rotor eccentricity,rotational speed,load torque and gear tooth stiffness are analyzed,providing the theoretical basis for the noise and vibration reduction of system.Setting the experimental platform,the instantaneous flow and the vibration of the elliptical gear pump is tested by digital turbine flowmeter and accelerometer respectively.The result shows that the flow pulsation can be effectively reduced by the external non-circular gear and the pump has the characteristics of multi-frequency vibration. |
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