Switchable Hydraulically Interconnected Suspension Modeling And Whole Vehicle Performance Analysis

As people·s living level is increasingly improving, automotive gradually becomes anindispensable traffic tool, especially SUV is more and more famous. In recent years,however, most of car accidents are caused by the vehicle rollover, the cause of vehiclerollover is complicated, such as unpredictable traffic conditions, drivers’ wrong operation,etc. With the emphasis on vehicle handling and safety, handling stability has becomeimportant research project. Lots of advanced suspension system can hold the balancebetween the handling and safety. These advanced suspension system can adjust thesuspension damping and stiffness to complete the adjustment of different vehicle drivingmodes. For example, active suspension, semi-active suspension. However, active suspensionand semi-active suspension are too expensive, and the performance stability is too poorer,the energy consumption is too much, and more complex than passive suspension structure.These conditions cause the greatly increasing vehicle cost. Currently, they only applied in ahandful of luxury cars and racing cars.According to the project, we develop the switchable hydraulically interconnectedsuspension (SHIS) system. By the early parameter measurement and road tests, we designSHIS system model, simulation analysis, parameters matching, sample manufacture and roadtests. This paper is based on test-simulation-test·, comparing the original vehicle with thetesting vehicle, to ensure the reliability of the research and development process. Followingaspects:(1) Characteristic analysis of damping unit of SHIS system. Based on hydraulicsimulation software AMESim, the simulation result is analyzed and the damping unit iscalculated. The simulation model is founded through comparing with the test curve. Structural parameters of the vibration damping units are identified by parameters matching.Then SHIS、HIS1and HIS2are founded by using AMESim software. And pitch stiffness ofHIS1and HIS2is analyzed. Finally, the sample is designed and processed.(2) Acceleration and braking switchable condition are determined. The key task toresearch SHIS is reducing body pitch attitude when cars accelerate and brake. It ensures theride comfort. The whole vehicle model is established by the CarSim software. Andacceleration and braking condition are also founded. Co-simulation with AMESim andMatlab/Simulink is established. Then switch parameters are determined under differentconditions. By comparing connection1with connection2, the best parameters are chosen byimproving the acceleration and braking body posture. Finally, the influence is ensuredthrough simulating to choose the primary parameters. In order to ensure the stability of pitchattitude, switch parameters should be optimized and the switchal instantaneous influence isanalyzed. Finally, control valve block is designed and processed, then installed on thevehicle.(3) Different connection types of SHIS play different roles in roll and riding. Accordingto the established vehicle model and SHIS hydraulic model, the simulation method is used toanalysis the vehicle performance influence of SHIS. Considering the roll attitude, steeringwheel angle step is set. Meanwhile seven degrees of freedom vehicle model is established byusing Matlab/Simulink. B and D grade roads are founded to do the comfort simulation test.(4) Vehicle road tests are verified. The four damping units and the control valve areinstalled on the car. The test way is as same as before. By comparing the original car, HIS1,HIS2and SHIS system, it can be seen that the SHIS system has large improvement instability on controlling the vehicle posture. At the same time, the riding is improving. So theresult is expected.