Study On The Performance Of Agricultural Tractor Powershift Transmission

The tractor is the most important agricultural machinery, which equipped with different implements such as suspended, pulled or attached to farm machinery operating units, to complete a variety of field operations and road transport operations. Electrically Controlled Powershift Transmission which apply the electro-hydraulic control technology in tractor gearbox, allows the gear to be shiftedunder load, and the power of tractor is not interrupted in the process, so that it improves the operational efficiency, reduces the labor intensity of the driver accordingly, and has a good prospect for high-powered tractors. Based on the project "Research and Development of High-powered tractors" which is the items3of "Research and Development of Economy-agriculture and forestry power machinery", the child of the Eleventh Five-Year National Science and Technology Support Project, A electrically controlled powershift and powershuttle transmission for YTO200hp wheeled tractors was developed, a shift control system was constructed, the software performance evaluation and the simulation research based on machine modeling was carried out, and the related test were accomplished, finally the development of entire transmission was finished. The main contents of the study are as follows:1.The structures and principles of the tractor powershift transmission were discussed. With the comparative analysis of the structural arrangement schemesof international powershift transmission which have the same power, and taking the manufacturing capacity of YTO into consideration, an appropriate transmission scheme was proposed, then the detail design was finished.The powershift and powershuttle wet clutch units which have reasonable structure and simple process were developed, and the related gear and shaft system were designed. The whoie transmission contains40forward gears and40reverse gears,its speed range is from0.3to50km/h.2. At the basis of comparison of hydraulic control and lubrication system of three famous transmissions in the world, a new hydraulic system was defined which has four step pressure relief valves. Then an integrated control valve block was developed, which can adjust the lubricating oil pressure and distribute the flow rate according to the importance ofcomponents in the transmission.Moreover, the required volume of lubrication oil was analyzed and calculated, finally be tested on test bench to confirm them.3. The software architecture of YTO200hp tractor was researched, and the shifting strategy both single shift and double shift were defined. Based on AUTOSAR the basic software and hardware of TCU were developed. Then the function and architecture of application software were defined.Based on Dymola, the plantmodel of engine, transmission and the resistance of tractor were set up and integrated to tractor modeLFinally, a joint simulation was carried out under the Matlab/Simulink and Targetlink circumstances to validate the software function.4. The testing procedures were defined, and a serial of experimental testing for powershift transmission and its core components (wet multi-plate clutches) were carried out on testbech, the aforementioned control model was validated and the software was calibrated, finally the test system and relevant test methods for powershift transmission was established.