Research On Vehicle Height Control And Energy Saving Of Electronically Controlled Closed Loop Air Suspension System

With the improvement of people’s requirement for the ride comfort, the application on commercial vehicle of air suspension is becoming increasing widespread, because it can make vehicle get good ride comfort and handling stability. As one new kind of electronically controlled air suspension, electronically controlled closed loop air suspension has the advantage of saving energy, lower noise, etc compared with the open loop air suspension. In the present circumstances of shortage energy, closed loop air suspension has a better prospect. Therefore, deep research on the aspects of vehicle height control and energy saving of electronically controlled closed loop air suspension has been done in this paper.Firstly, according to the charging and discharging process of closed loop air suspension, the air pressure system was simplified into a circuit composed of gas tank, air spring, air compressors and centralized air resistance. Then their mathematical models were built, especially the working process of air compressor in the closed loop air suspension was analyzed and calculated, which inlet air pressure was not atmospheric pressure.Secondly, by analyzing the vehicle height control process of closed loop air suspension, control strategy and target were made. For avoiding the overshoot phenomenon and ensuring vehicle body horizontal, discrete universe fuzzy PWM control unit based on half vehicle was designed and simulated by Simulink. Its result shows that this controller could make the vehicle height adjusting achieve the control target. Through building physical model of system in AMESim and simulation, the validity of built mathematical model and controller was verified by compared with the simulation result based on mathematical model.Finally, for analyzing the energy saving effect of closed loop air suspension, the calculation methods of energy for closed and open loop systems were proposed. Then the effects of initial pressure and volume of gas tank on the energy saving and vehicle height adjusting were calculated by Simulink. The energy saving effect of closed loop air suspension compared with open loop air suspension was obtained. It shows that the closed loop air suspension could save plenty of energy.