The Research For Electronic-controlled Pneumatic Adjustable Shock Absorber Of Bus Air Suspension

Air suspension improves the ride comfort,vehicle maneuverability,and road holding ability,etc.Furthermore,it decreases road impact of wheel dynamic load.Therefore,research and development of air suspension attracts more attention.The ordinary air suspension only control air suspension’s air sac pressure,the bias frequency of sprung mass keep relatively stable,the shock absorber of the suspension is passive and the performance of shock absorber is not adjustable.Recently,air suspension of a few high-grade abroad commercial vehicle matches the adjustable shock absorber with air spring to make the stiffness and damping of the suspension controllable which adapts to different driving conditions and set the ride comfort and vehicle maneuverability in good condition.Such research in the electronic-controlled air suspension is not yet reported.The thesis has a systematic research on the adjustable shock absorber of the electronic-controlled bus air suspension from aspects such as structure design,model building and simulation,property Test, on board test.Major work is as follows:The thesis introduced the development status and key technology of air suspension system and adjustable shock absorber.On this basis,according to the damping control demand of YBL6891H bus ECAS,the thesis designed a adjustable shock absorber with two types damping,which using new type electronic-controlled pneumatic drive mechanism.The action control accuracy and response speed are superior to stepping motor drive mechanism.The thesis introduced structure composition of this shock absorber and selection of drive mechanism parts,analysis the working principle of damping adjustment.The thesis further studied the deformation of spring valve plate which is the key problem for affecting precision of shock absorber mathmatic model, and calculated the deformation of spring valve plate by using "conjugate beam method" and "finite element analysis method",compared with the difference of two methods.Hypermesh and ABAQUS finite element analysis software is used to calculate the quantitative relation of the pressure and deformation of spring valve plate.The functional relationship was obtained by using least square method.The parameterized mathematical model of two types damping states was established.Matlab software is used to simulate damping characteristics of shock absorber,which provided theory basis for its optimization of structural parameters.The adjustable shock absorber sample were developed and the damping characteristics of it were tested.The deviation of the tested damping and design goal was less than 6%,the deviation of the tested damping and the simulation values was less than 10%.It was shown that the design scheme of shock absorber was valid;The simulation results which was calculated by using "finite element analysis method" were more close to the test results,it provided scientific basis for improving the precision of mathematical model.Finally,The ride comfort test was carried on after the adjustable shock absorber was installed on the YBL6891H bus.When the bus is on B-class road, fully loaded,at the speed of 50km/h,the damping mode of the adjustable absorber is set to "soft".As a result the T_CD value of the chair close to the rear axle raises to 4.2h,comparing to the 2.8h tested by adopting the passive absorber.It showed that the ride comfort of the bus could be improved obviously for electronic-controlled pneumatic adjustable shock absorber.