| As a kind of major off-road machine in earth-rock construction,loaders are commonly used in shoveling,raising and unloading materials.China has been stably ranked first in the world for the production and sale of loaders in recent years,while the lack of critical innovation in technology and technical features of the manufacturers causes the homogenization and ferocious price competition of domestic market of loaders nevertheless.Therefore,the technical progress of loaders is of vital importance.This paper takes loaders equipped with bi-variable hydraulic system as the object.Researches on the dynamic power matching and energy-saving control technology of loaders are based on plenty of laboratory data on loader steering,I-cycle,V-cycle,combined with digital variable technology,extreme traction control,single handle steering and Equal-intensity-casted arm with variable cross section,which are realized in China for the first time.From the view of the energy-saving problem of hydraulic system,Mechanical optimization is completed to stabilize the pressure of steering system and comparison analysis between quantitative system is done to find the energy-saving properties of the hydraulic system in variable working device.In addition,a sort of digital variable technology feasible for loaders is raised.From the view of power,staged power matching control strategy based on V-cycle and extreme traction shovel loading power matching control strategy are proposed.The research work included in the paper is as follows:(1)Mechanism optimized model of steering system based on genetic algorithm is built to solve the problem of large power variation and waste of steering system.From the view of the hinge point location of steering cylinder and transfer function of steering system,mechanism optimized model of steering system based on genetic algorithm is utilized to design optimized program of steering system and optimize the location of the hinge point and the size of Steering cylinder.No evident stress variation is found during experiments of the optimized steering hydraulic system,thus the stability and power efficiency of Steering hydraulic system is improved.(2)A method to improve the power efficiency of hydraulic system by optimizing the working device mechanism is proposed.Researches on the energy-saving properties of working device mechanism are done by experiments and simulation.The model of variable working device with Load-sensitive hydraulic system is built and comparison of energy consumption between quantitative systems are done under varied working conditions.The energy-saving properties and the demerits of Variable system are obtained by arm-lifting and I-cycle experiments.The theoretical analysis and laboratory validation are executed on the energy-saving control technology of variable hydraulic system applied to the loader.Digital variable technology is raised according to the theorem of loader-sensitive variable hydraulic system.Control strategies are improved based on varied working conditions.Software programming is completed and the laboratory platform is built.(3)Power matching control strategy of machine based on graphic identifying algorithm is proposed in order to improve the power efficiency of loaders.Theoretical calculations of shoveling-operation resistance for different materials are executed and validated by shovel loading experiments.Material-identified model is built on the basis of graphic identifying algorithm.Shovel loading control strategy is proposed based on material identifying and validated effective by shovel loading experiments,which realizes automatic switch of engine working condition and reduction of oil consumption.(4)Drag-Reduction-Inserting Mechanism is raised and extreme traction shovel loading is realized to reduce the power efficiency caused by tyre sliding in shovel loading stage.The generation mechanism of shoveling-operation resistance and Insertion method of drag reduction by shoveling is suggested.PSO-SVM model is built on the basis of huge amount of laboratory data from shovel loading experiments,resulting in the balance of tractive force and lifting force.Two methods of extreme traction shovel loading control strategy(i.e.A.based on Torque Difference;B.based on revolution speed difference)are proposed,reducing the peak power of shovel loading,realizing the dynamic matching of engine power,thus the control strategy is validated to be effective. |
