Study On Vehicle Height Adjustment And Energy Consumption Characteristics Of Closed-Loop Air Circuit Laterally Interconnected Air Suspension

With the development of modern vehicle suspension technology, a new structure of interconnected air suspension which based on traditional air suspension structure can provide better performance of ride comfort. Compared with traditional air suspension, the adjacent air springs in the interconnected air suspension are connected by pneumatic pipelines. When suffered pavement impacting, there will be gas exchange between the interconnected air springs, which can relieve the pavement impact and maintain the vehicle body attitude. In order to further improve the dynamic performance and energyeconomic performance of air suspension, a closed-loop air circuit laterally interconnected air suspension structure which combines the advantages of both interconnected air suspension system and closed-loop air circuit air suspension height adjustment system with high and low pressure tanks was proposed. The vehicle height adjustment performance and energy consumption characteristics were studied in this paper.Firstly, the working principle of closed-loop air circuit laterally interconnected air suspension system was introduced, and the mathematical models of gas tanks, solenoid valves, air springs were established combined with the principle of gas thermodynamics in MATLAB/Simulink; The vehicle height adjustment model of closed-loop air circuit laterally interconnected air suspension system was established combined with the theory of vehicle dynamics in MATLAB/Simulink.Secondly, in order to solve some problems existing in the traditional vehicle height adjustment strategy, such as long adjustment time and overshoot phenomenon, the traditional PID control strategy was improved to build a special integral separation PID height control strategy for laterally interconnected air suspension system. The optimal parameters of PID control strategy was obtained by genetic algorithm. Besides, the body attitude correction coefficient was introduced to ensure the stability when vehicle height was adjusting. Simulation results showed that the control strategy can adjust body height rapidly and accurately, the overshoot phenomenon was avoided, some portability defects existed when traditional air suspension height control strategy applied to the interconnected suspension system was solved.Thirdly, a vehicle height adjustment experiment was carried out on a test bench and the impact of different initial pressure of gas tank on the charging/discharging time as well as the steady-state error during the vehicle height adjustment were studied based on D2 P rapid prototyping platform. The experimental results showed that the control strategy for the closed-loop air circuit laterally interconnected air suspension system can adjust the vehicle body height rapidly and accurately. The correctness of the mathematical model and the validity of control strategy were verified. The study about the impact of gas tank initial pressure provides a theoretical basis for the setting of the vehicle height adjustment system parameters.Finally, the characteristics of energy consumption in the process of boosting for closed-loop air circuit laterally interconnected air suspension system were researched. The energy consumption was calculated by the parameters of compressed gas available energy and air compressor work. The characteristics of energy consumption for closedloop air circuit air suspension system was verified via a test bench. Both theory and test results showed that the energy economic performance of closed-loop air circuit system applied to vehicle height adjustment system was remarkable compared with open-loop air circuit system. A lower initial pressure of high pressure tank and a higher initial pressure of low pressure tank were beneficial to energy economic performance when boosting the same gas pressure.