Abstract
This paper presents a theoretical approach for lowering the outlet flow ripple of a crescent pump by applying a tandem crescent pump consisting of two gear pairs with an index angle between them. The outlet flow of the tandem pump is obtained by summing the flow produced by the two gear pairs, and the flow ripple of the tandem pump can be attenuated by properly selecting the design parameters in terms of the index angle and the displacement ratio between the two gear pairs. A lumped parameter model is presented for evaluating the crescent pump’s flow ripples, and experiments were performed on a single crescent pump to validate the model from the aspects of the steady-state flow-pressure characteristics and the outlet pressure ripples. In this way, the main causes of the flow ripple could be identified by comparing the kinematic flow with the actual flow evaluated by the model. Additionally, simulation results suggested that a tandem pump with an index angle of 13.85° and displacement ratio of 0.5 could lead to a more than 45% decrease in the outlet flow ripple than a single pump with the same displacement in a wide range of operating conditions.
Highlights
Crescent pumps are widely used in many fluid power applications such as injection molding machines, automotive applications, and robotic systems due to their advantages in terms of compactness, low flow ripple, and low noise level [1,2,3]
This paper focused on a theoretical approach for lowering the flow ripple by applying a tandem crescent pump comprised of two sets of gear pairs with an index angle between them
This paper focused on the flow ripple of the tandem crescent pump via a lumped parameter model built in Matlab
Summary
Crescent pumps are widely used in many fluid power applications such as injection molding machines, automotive applications, and robotic systems due to their advantages in terms of compactness, low flow ripple, and low noise level [1,2,3]. This paper focused on a theoretical approach for lowering the flow ripple by applying a tandem crescent pump comprised of two sets of gear pairs with an index angle between them. Manring et al [21,22] addressed the theoretical torque ripple and flow ripple of a tandem axial piston pump with two identical rotating groups under different index angles from a kinematic aspect, suggesting that an index angle of 10◦. Xu et al [23] studied the tandem piston pump’s flow ripple via a lumped parameter model using LMS Amesim, suggesting that an index angle of 20◦ resulted in the greatest reduction of the flow ripple. It was expected that the tandem crescent pump could lead to a decrease in the flow ripple through the proper selection of the design parameters in terms of the index angle and the displacement ratio. The rest of the paper is organized as follows: the simulation model is proposed in Section 2 focusing on the evaluations of the flow and pressure in the sealing chambers around the gear circumference; the validation of the model is conducted in Section 3 from the aspects of the steady-state flowrate and the outlet pressure ripples; the numerical results are presented in Section 4 regarding the pump’s outlet flow and the related flow ripples; and discussions and conclusions are made in Section 5 based on the numerical results
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