Simulation of Hydraulic Cylinder Cushioning

Abstract

The internal cushioning systems of hydraulic linear actuators avoid mechanical shocks at the end of their stroke. The design where the piston with perimeter grooves regulates the flow by standing in front of the outlet port has been investigated. First, a bond graph dynamic model has been developed, including the flow throughout the internal cushion design, characterized in detail by computational fluid-dynamic simulation. Following this, the radial movement of the piston and the fluid-dynamic coefficients, experimentally validated, are integrated into the dynamic model. The registered radial movement is in coherence with the significant drag force estimated in the CFD simulation, generated by the flow through the grooves, where the laminar flow regime predominates. Ultimately, the model aims to predict the behavior of the cushioning during the movement of the arm of an excavator. The analytical model developed predicts the performance of the cushioning system, in coherence with empirical results. There is an optimal behavior, highly influenced by the mechanical stress conditions of the system, subject to a compromise between an increasing section of the grooves and an optimization of the radial gap.

Aspects Regarding the Dynamic Behavior of a Hydraulic Cylinder

“…In (Schwartz et al, 2005) one can see a study on dynamic self-regulating brake. It was used tapered bushings mounted on both sides of the piston, or grooves, varying in number and design, which are important for the control of the passage section to the connections of the hydraulic cylinder (Algar et al, 2021). Another study, developed by Algar and collaborators, reveals the radial forces caused by the movement of the piston between the cylinder connections.…”