Research On The Power-train Hybridization And Parameter Matching Of Hydraulic Excavators

Nowadays,energy saving and exaust reduction have become the main objects for construction machinery.However,it is hard for the conventional methods to further improve energy saving.So new technology is urgently needed.The hybrid power technology is paid much attention to by energy saving researchers of construction machinery due to its good performance in hev.Hybrid excavator is a new research direction.Only several foreign companys have produced prototypes of hybrid excavator and we just start research on it.This thesis mainly centralized research on the key technologies of hybrid hydraulic excavator,and the research progress is as follows:1.Three types of hybrid configurations are studied based on the simulation model.After comparing their mian performances,the parallel configuration in which the NIMH batteries are directly connected with the DC/AC converter is chosen to be the basic configuration for further study.2.A kind of parameter matching method based on hyrid factor optimization is proposed and is used in the parameter design of a 5-ton hybrid hydraulic excavator.The simulation result shows that the proposed method can realize parameter optimization between the main power source and the auxiliary one.3.A control strategy based on load recognition and dynamic hybrid factor optimization is proposed.It realizes power matching among the power source,the hydraulic pump and the load.Meanwhile it optimizes the working points of the two power sources by which the fuel consumption can be reduced.4.A kind of SOC estimation strategy based on the law of energy conservation and four-line's measurement is proposed.This strategy can be used to estimate the SOC of the batteries working under high charging/discharging rates.5.A test bench of 5-ton hybrid hydraulic excavator is built.And the key technologies studied in this thesis are experimented on this test bench.