Simulation And Experimental Research On Shocks Of 816G Gear-box Power Shift

In recent years,engineering vehicles such as loaders have been put into use with the continuous increase of national investment in infrastructure construction.Comparing with manual gearshift gear-box,power gearshift gear-box could free drivers from frequent shifting,and reduce security risks caused by frequent operations.In our country,power gearshift gear-box is used for engineering vehicles mostly.But the problem of sharp shock during using process reveals gradually as while.And it not only reduces the driving comfort,but also shortens the service life of the vehicle.Therefore,more and more scholars and manufacturers focus on improving the shifting shock problem of shift gearbox and improving the shifting quality.Relyed on university-enterprise cooperation project ‘ 816 G Shift Shock Analysis based on AMESim',the research's focuses on the problems of whole machine's movements during shift process and gear's sound of gearbox,taking 816 G small loader as the research object.And the author analyzes causes and influence factors of shift shocks from the whole transmission system under combination of theoretical analysis,AMESim simulation,and experiment.And then optimization scheme is put forward for buffer system.The main contents are as follows:1.General description of gearbox's types and features,and literature review about shift quality of engineering vehicle power shift gearbox.By analyzing the 816 G machine transmission system,the author starts from improving the performances of shift control valve and improves the shift smoothness with buffer control method under current conditions.In terms of the evaluation index of gear shifting quality,it is determined that shock degree is used as the objective evaluation index.Driver's satisfaction degree is taken as the final evaluation standard in practical application under the principles of comfort consistency of objective and subjective indicators.2.Analysing working principles of power shift gearbox and establishingmathematical model of power shift control valve.The author anyalyzes impacts on shift shocks through changing the orifice's size and stiffness of reset spring,Directional spring and reversing spring.AMESim was used to establish the simulation model of 816 G shift control valve.And after the simulation analysis,one conclusion was drawn that,the buffer time is affected by the orifice diameter and the stiffness of the reset spring.Then nine parameter combinations were given.3.Experimental research was carried out on the basis of theoretical analysis of power shift control valve and AMESim simulation model construction.We use pressure sensor to arrange key measuring points for 816 G shift control valve.And we test the shift performance of the system in the shift process through simulating several typical operating conditions.The correctness of the model was verified by sorting out the collected data,analyzing the test results and comparing them with the model established before.The working characteristics of the shift buffer valve was also understood.4.The test also proves that the current buffer valve can not play a good buffer role,and shift shock is big.The buffer system was optimized by changing the orifice diameter and the stiffness of the reset spring,and the buffer time of the system was adjusted according to the body's acceptable impact.