Analysis And Optimization Of Hydro-Pneumatic Spring Based On Ride Comfort Of Mining Dump Truck

As one of off-road vehicles,mining dump truck is considered to meet the requirements of current mine haulage industry.Operator in a mining dump truck needs to work with the wide difference of vehicle loads due to severe operation environment and complex road conditions,which put forward high standard of mining dump truck performances.As one of the most significant performances,the ride comfort can bring impact on the comfort of operator directly,vehicle dynamic performance and service life of accessories.Wide vehicle loads difference of mining dump truck also affect the smoothness of it under circumstance of empty-load and full-load.Therefore,the priority of high-quality mine haulage performance for mining dump truck is the enhanced smoothness of truck operating under various situations.In this work,the analysis and optimization of hydro-pneumatic spring characteristic and vehicle smoothness were investigated with the mining dump truck operating at empty-load and full-load,respectively.The output-force model of hydro-pneumatic spring was established with Matlab/Simulink.With the output-force model,the hydro-pneumatic suspension model for the whole vehicle was set,which was determined by the effect of various operation and structure parameters for elastic force,damping force and output force in hydro-pneumatic spring.The random excitation was used on the road surface.The vehicle smoothness was analyzed with C,D and E grade roads at the speed rang from 20km/h to 40km/h.Then,with the change of suspension parameters,the influence of annular cavity area in hydro-pneumatic spring,damping hole diameter and diameter of one-way valve for vehicle smoothness was under investigation,which exhibited the optimum value of hydro-pneumatic spring parameters in suspensions with the smoothness at empty-load and full-load.The fuzzy PID control was finally used to optimize the eight degrees of freedom hydro-pneumatic suspension truck model in terms of object variables including barycenter acceleration,pitch angle acceleration,roll angle acceleration and seat acceleration.With four fuzzy PID controllers,four hydro-pneumatic springs with active control force were research,which achieved the optimization of the vehicle smoothness.Results in this work showed the obvious nonlinearity of elastic force and damping force in hydro-pneumatic spring.In addition,changes of operation parameter and structure parameter also brought impact on output force.In the four DOF model,the worse smoothness of truck working at empty-load and full-load was observed due to higher acceleration of barycenter and pitch angle at empty-load.With the structure parameter modification of hydro-pneumatic springs both in front and rear suspensions,various impact on vehicle movement,barycenter acceleration,pitch angle acceleration and suspension dynamic travel can be observed,which presented the optimum values.With the fuzzy PID controller applied in the eight DOF hydro-pneumatic suspension model,the enhanced smoothness can be achieved in the mining dump truck.