The Study On Boom Potential Energy Recovery Technology Of Hydraulic Excavator

Hydraulic excavator is the construction machinery with high energy consumption andhigh emission. With increasing construction project in the world, the sales of Hydraulicexcavator are increasing year by year. Therefore, the study on energy-saving technology ofhydraulic excavators has important practical significance to reduce the consumption ofconventional energy sources and improve the environment. The manipulator movements ofHydraulic excavator are more frequent in the work process, and the gravitational potentialenergy of manipulator is dissipated into heat in the control valves when the manipulator goesdown. It can further improve the energy-saving effect if gravitational potential energy ofmanipulator can be recovered and reused.At present，the study on manipulator potential energy recovery technology of Hydraulicexcavator focused on the development of energy recovery system with hydraulic open loop,which will lead to throttling losses and bypass losses. This Ph.D. dissertation is developedunder the project named “the key technology and system development of new hybridconstruction machinery (2009AA044403)” which is supported by National High TechnologyResearch and Development Program863. According to the actual operating conditions of thehydraulic excavator boom, this paper has made a deep and systematical research on boompotential energy recovery technology and some innovative contributions are enumerated asfollows.1. Boom potential energy recovery system with closed circuit in hydraulic excavatorswas put forward, which control brushless dc motor using control algorithm of fuzzy PIauto-tuning to achieve volumetric speed control. It can achieve exactly power match betweensystem input power and load required power.2. The mathematical models of Boom potential energy recovery system with closedcircuit were built on the basis of the system working principles, and control strategy ofsystem was proposed according to and the analysis on motion law of the constituent links. The changes characteristics of cylinder rod velocity, accumulator pressure and hydrauliccylinder pressure were analyzed via numerical simulation under variable load operatingconditions of boom.3. The experiment bench was set up and the simulation results were verified by benchtest. The results showed that the simulation results were correct and the boom potentialenergy recovery system with closed circuit works steadily. Compared with the traditionalvale-controlled system of the hydraulic excavator, the system has higher operating efficiencyand higher energy saving.Other researches are:1.8-ton Hydraulic excavator model was built for multi-body dynamics, hydraulicsystem and system energy loss model. The regenerated energy of the boom, the arm, thebucket and swing were calculated in the typical working cycle and typical working cycleexperiment was carried out, which can provide theoretical basis to explore the energy-savingpotential of the system and find the main direction of the energy recovery research.2. Energy exchange relation among very power element was analyzed on the basis ofenergy-saving mechanism of boom potential energy recovery system with closed circuit. Themain components parameter matching of boom potential energy recovery system was carriedout according to the parameter8-ton Hydraulic excavator.3. Magnet brushless dc motor model was built and the speed adjusting performance andanti-jamming performance of Magnet brushless dc motor were analyzed via numericalsimulation. The results showed fuzzy PI auto-tuning controller has better dynamic controlquality, which applies to volumetric speed control of boom potential energy recovery systemwith closed circuit.