Research On Shifting Control Strategy Of Motor Grader With Multi-full Load Characteristic Engine

Due to the wide operating range of motor grader,it is difficult for the engine with a single full load characteristic curve to match various working conditions effectively.The application of hydro-mechanical transmission enhances the load adaptability of the motor grader,but also leads to the problem of low transmission efficiency and high energy consumption.In this paper,the hydro-mechanical motor grader based on multi-full load characteristic curves is adopted as the research object,and its different shift control strategies are studied to improve the power and economy of the grader.Firstly,according to the operation characteristics of the grader,the setting of three full load characteristic curves from the perspective of operation conditions and road surface characteristics is proposed through qualitative analysis,and their control principles are analyzed.On this basis,the whole vehicle dynamic matching of the hydraulic mechanical power transmission system was carried out,and the gear shifting mode and the locking scheme of the torque converter in the article have been determined based on the power output characteristics.Secondly,the locking law is analyzed based on the locking scheme of the torque converter.In order to address the difficulty of balancing power,economy,and locking quality in torque converter locking,a locking point based on the average level difference of the gearbox speed ratio is proposed,and a single locking point is optimized according to the actual needs of different working conditions.A combined locking design based on working conditions is proposed.Then,combined with the shift mode,the study focused on automatic shifting,adopting a dual parameter shift law based on driving speed and throttle opening.Based on different optimization objectives,dynamic shifting,efficiency shifting,and comprehensive shifting control strategies were developed,and the shifting model was constructed using Statechart;At the same time,in response to the constant locking state of the hydraulic torque converter during manual model,extreme load protection is used to prevent the engine from stalling,and a slope shifting method is selected to reduce shifting impact.Finally,the simulation model was built using AMESim to conduct simulation experiments and analyze the shift control strategy proposed in this paper.The following conclusions were drawn based on the evaluation indicators of power,economy,and shifting quality: compared with a single full load characteristic curve,the design of three full load characteristic curves is more fuel-efficient with a maximum fuel saving of 13.7%;The comprehensive shift pattern can improve work efficiency by 2.2% while reducing fuel consumption by 2.6%,which can balance the economy and power of the entire machine;Combined locking combines the advantages of coupling locking and differential locking,increasing the operating efficiency by 10.7% and reducing fuel consumption by 3.2% while reducing the maximum impact of locking by 88.3%.The performance of grader has been improved obviously by adopting the design of comprehensive shift schedule and combined locking.