Modeling and verification of rotor pump efficiency and flow on calculus methods

As a critical element in transmission lubrication and hydraulic control systems, the rotor oil pump plays a decisive role in determining the effectiveness of lubrication and control in automatic transmissions, thereby influencing their overall lifespan. To optimize energy utilization and reduce system energy losses, it is essential to explore the key factors affecting the efficiency of rotor pumps and enhance their operational performance. Traditional studies on rotor pumps typically emphasize performance indicators such as flow rate and output torque, often relying on finite element simulations. However, while finite element methods provide useful insights into flow and torque characteristics, they are limited by long computational durations and high sensitivity to boundary condition assumptions, which are frequently subjective. Consequently, they offer limited accuracy in evaluating critical parameters like volumetric and mechanical efficiency. To overcome these limitations, this study develops a lumped parameter model derived from a detailed analysis of the volume variation within a single pump cavity. The model incorporates the deformation characteristics of the leakage area and achieves a balance between modeling simplicity, computational efficiency, and predictive accuracy. The leakage zone between high- and low-pressure regions—characterized by non-uniform thickness—is found to significantly affect pump efficiency, necessitating quantitative evaluation of its impact.

In this research, the rotor pump serves as the primary object of investigation. A volume cavity model is formulated using the lumped parameter approach, taking into account the deformation of the leakage zone. Based on precise modeling of the volume change, separate models for volumetric and mechanical losses are constructed. Analysis reveals that the clearance between the cover plate and the rotors contributes significantly to drag torque, thereby influencing mechanical efficiency. Experimental testing is conducted to validate the model, with the results used to examine changes in outlet flow, input torque, and various efficiency metrics, including volumetric, mechanical, and total efficiency. The experimental outcomes verify the effectiveness and accuracy of the lumped parameter model in assessing rotor pump performance. Findings indicate that with increasing outlet pressure, hydraulic force and axial preload tend to balance, leading to reduced friction torque and an initial rise in mechanical efficiency. However, higher temperatures reduce oil viscosity, adversely affecting volumetric efficiency. These results imply that maintaining effective thermal management in rotor pump systems is critical for achieving enhanced overall efficiency.