Modeling and Optimization of the Control Strategy for the Hydraulic System of an Articulated Boom Lift

摘要

This paper describes the numerical modeling of the hydraulic circuit of a self-moving boom lift. Boom lifts consist of several hydraulic actuators, each of them performs a specific movement. Hydraulic systems for lifting applications must ensure consistent performance no matter what the load and how many users are in operation at the same time. Common solutions comprise a fixed or a variable displacement pump with load-sensing control strategy. Instead, the hydraulic circuit studied in this paper includes a fixed displacement pump and an innovative (patented) proportional valve assembly. Each proportional valve (one for each user) permits a flow regulation for all typical load conditions and movement simultaneously. The study of the hydraulic system required a detailed modeling of some components such as: the overcenter valves, for the control of the assistive loads; the proportional valve, which keeps a constant flow independently of pressure drop across itself. The model of the hydraulic circuit has been implemented in AMESim simulation environment, integrating also a mechanical model for loads, in order to evaluate the instantaneous forces acting on the actuators and depending on the position of mechanism in the machine. The aim of this study is to find the best way to control the prime motor, in order to obtain the optimal controllability reducing the energy losses in the system by varying the speed of the pump by means of an Electronic Controller (EC).