Optimization And Test Of Damping Mechanism For Seat Suspension Of Agricultural Vehicle

Traditional agricultural vehicles are mainly used to complete specific tasks related to agriculture.At present,many researches has been done on the functions and purposes of agricultural vehicles,but pay less attention to their impacts on the physical and mental health of drivers.With China put more emphasis on the “three issues of agriculture,the countryside and farmers”,the research on the physical and mental health and operational comfort of agricultural vehicle users has become an issue that people increasingly concerned about.The road conditions of agricultural vehicles are complex and heterogeneous.Compared with road vehicles,the vibration generated by agricultural vehicles has a more significant impact on human health.The traditional agricultural vehicle driving seat structure is simple,and the mitigation effect of the vibration generated during the working process of the agricultural vehicle is not obvious,and some seats even amplify the vibration.In order to improve the comfort of agricultural vehicle workers,more and more scientific researchers and companies have conducted researches on the comfort of agricultural vehicle seats.Based on the vibration characteristics of agricultural vehicle,this dissertation designeda damping mechanism for seat suspension of agricultural vehicle.The main contents include the following aspects:Firstly,to examine the vibration of agricultural vehicles at work.Acceleration sensors,posture sensors and information collectors are used to collect the data of vibration acceleration,displacement and angle changes of the tractor seat chassis in real time and the acquired data is analyzed to obtain the vibration rules of the seat during operation.Secondly,to design a nonlinear seat suspension with vibration damping performance.Based on the analysis of the principle and superiority of the nonlinear vibration damping mechanism,the designed suspension structure was optimized,and the springs and cams used in the seat suspension were analyzed,deduced and designed.By using Creo 3D modeling software,the suspension was modeled according to the virtual 3D engineeringview and the 2D engineering view.The physical model of the seat suspension was obtained.Finally,the different structures in the designed nonlinear suspension were tested and analyzed.The test mainly studied the damping effect when different cams and rollers contacted in a non-linear seat suspension.The test was performed on a circular cam(38mm in diameter),the circular cam was replaced by an elliptical cam to measure the RMS acceleration and amplitude attenuation of the seat suspension,the damping effect of the nonlinear seat suspension was evaluated.The results showed that:1)The minor axis of the elliptical cam is controlled to be unchanged(38mm),and the long axis(38-46mm)is changed.The results show that the vibration damping effect is good at the low frequency stage when the long diameter is 42 mm.When the long diameter is38 mm,the damping effect is good at the high frequency stage.That is to say,when the long diameter is increased to 42 mm in the low-frequency phase,the vibration damping effect has reached the best.In the high-frequency phase,there has the best vibration damping effect when the long diameter is 38 mm,indicating that in the high-frequency phase,the vibration damping effect decreases as the long diameter increases.2)The long axis of the ellipse is unchanged(44mm)and the minor axis(44-32mm)of the ellipse is changed.The data shows that the vibration isolation effect is optimal when the short diameter is 32 mm in both the high frequency band and the low frequency band.Namely,in the process where the major axis is 44 mm and the minor axis continuously varies among 32-40,the smaller minor axis 32 mm exerts a stable damping effect.That is,as the minor axis increases in this interval,the damping effect decreases instead.Many experimental platforms that perform vibration tests can only perform one-way vibration tests,and cannot actually simulate the actual operation of agricultural vehicles.One-way vibration test is far from the actual vibration,which results in significant difference between the test effect and the actual effect.The test adopts a six-degree-of-freedom vibration platform that can simulate the vibration of the tractor,which can overcome the large differences in the experimental process.The cam structure of the non-linear seat suspension was optimized through tests on the vibration platform,the teset obtained a cam that is more suitable than a circular cam(38 mm in diameter).The testresults show that the came with the long axis of 44 mm and the minor axis of 32 mm is more suitable for the nonlinear suspension of the structure.