Research On Shift Strategy Of Tractor Power Shift Transmission

As the main power output machinery of agricultural machinery,tractor plays a decisive role in the process of agricultural mechanization.Due to the introduction of precise agriculture,the requirements for tractor operations are higher and higher.The quality of the transmission determines the power,fuel economy and driving operability of the tractor.When working in the field,the traditional manual transmission requires the driver to meet the dynamic requirements according to the external load and the operating speed requirements.Frequent shifts increase driver fatigue,and the driver's operating level is different,which has a great influence on the tractor's power,economy and driving comfort.Therefore,in order to simplify the operation of the tractor and improve the quality and efficiency of the tractor operation,research on the automatic shifting law of the tractor contributes to the development of agricultural mechanization.This paper takes Dongfanghong 1804 as the research object,and studies the shifting rules of tractors during field operations.Mainly from the following aspects:(1)Study the background and significance of the tractor automatic shift transmission,the current mainstream transmission structure and characteristics of the tractor are analyzed,and the status of the transmissions used by tractors at home and abroad is studied.At the same time,the current situation of shifting laws at home and abroad is studied,and the problems of the current shifting rules of tractors are pointed out.(2)Analysis of tractor operation mode.According to the demand power and speed of each mode of the tractor,the operation is divided into field heavy load mode,light load mode and road mode.Analyze the tractor transmission structure,power shifting principle and working resistance,and establish the vehicle dynamics and simulation system model to lay the foundation for subsequent theoretical research.(3)Analyze the commonly used shifting parameters of the tractor,and determine the parameters of the shifting rules in this paper.According to the operation mode,the shifting rules are divided into three types.According to the different purposes of different modes of operation,the corresponding shifting rules are formulated,which lays a theoretical foundation for the subsequent correction of shifting rules according to the impact of field operations.(4)Analysis of the factors affecting the tractor operation mode,Considering the heavy load slip rate and high load have great influence on the operation,the effects of slip rate and load on the tractor are studied respectively,and the shifting rules are corrected according to these two factors.Considering the high speed requirement under light load operation,use fuzzy-PID to control the throttle opening.When the load changes greatly,the shift is corrected to stabilize the speed and increase the engine load rate;Considering that the weight of the goods changes when the tractor transports the crops,the maximum mass that can be transported by the tractor is determined,and the change law is corrected according to the quality.