| Electric control suspension system can change its stiffness and damping parameters with the change of the driving environment,therefore vehicles' ride comfort and safety performances have been significantly improved,technologies about it have been the hot spot of domestic and foreign research of automobile chassis in recent years.The suspension stiffness and damping are controlled independently in most of the research,so it is difficult to achieve real-time optimal matching of stiffness and damping the driving environment are always changing.A new type of suspension strut,which are composed of air spring and shock absorber has adjustable stiffness and damping characteristics,it can improve the performance of Vehicle ride comfort,handling stability and road friendliness.Taking a light off-road vehicle as the research object,the integrated strut is applied to the rear suspension of the off-road vehicle,parameters of the rear suspension are matched and optimized.According to the requirements of the design and development of rear suspension,a integrated absorber strut is designed,developed the adaptive mode switching control strategy of rear suspension stiffness and damping,lay the foundation for the development and application of new electronic control suspension in off-road vehicle.This paper introduces the structure and working principle of the new type of integrative shock strut which was designed by my research group,absorber damping gear adjusting mechanism was analyzed,the coupling relationship between shock absorber strut main and auxiliary air chamber and the absorber oil cavity fluid was analyzed through the physical model.Aiming at a light-weight off-road vehicle rear suspension system,replaced hydraulic shock absorber with integrated absorber strut to constitute a compound suspension with the leaf spring,a 1/4 dynamic model in Simulink is established,a multi-objective optimization model is established with the use of particle swarm optimization algorithm considering ride comfort handling stability and security,compiled optimization procedures in Matlab to optimize and match ear suspension stiffness and damping under the for typical conditions.According to the matching requirements of off-road vehicle composite suspension stiffness and damping,designed parameters and simulated the stiffness and damping characteristics of integrated shock absorber strut,determined the values of three kinds of air pressure of the air spring strut and three damping state.The prototype strut was developed for the stiffness and damping characteristics bench the test,the test results coincide with the simulation results.According to the decision control theory,the rear suspension working state can be divided into four modes,rear suspension multi mode adaptive switch controller is designed in Simulink/stateflow.To analyze the muti-mode control strategys' influences on vehicle performences in all aspects,a vibration vehicle model with seven degree of freedom was built,simulation results show that rear suspension with multi mode switching controller can effectively improve off-road vehicles' ride performance,the body acceleration,tire dynamic load and the dynamic deflection of the suspension are all improved to some extent. |
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