Research On Building Parameter Model, Analysis And Design Theory And Method Of Air Suspension Of Automobile

Air suspension system can reduce not only the vibration and noises of vehicles but also the dynamic loads of wheels. The vehicles which are equipped with air suspension system can get perfect connatural frequency and better comfortable performance when they are running, better stability when being controlled, better safety performance when they are running. So air suspension has wide application and development foreground. The dissertation progresses the theory analysis by the numbers and simulation research in allusion to two kinds of pivotal technology of the air suspension, the design method of air suspension and the design technology and theory of the direction framework and all kinds of bracket fixed on air suspension.The dissertation synthetically by the numbers analyzes the research actuality on air suspension in our country and foreign countries, the design method and application instance of air suspension based on reading a number of research papers on air spring and air suspension and investigating widely correlative factories in our country. Then ulteriorly the main components of air suspension and the different structure of the direction framework are introduced and the strongpoint of air suspension compared with armor plate spring suspension is expounded. The theory analysis in allusion to the direction framework of a kind of air suspension is processed taking use of Langrate method of the multi-body dynamics theory. At the same time the kinematics analysis of rigid body and elasticity is also processed based on Virtual Prototype Technique which is popular in the world and the changing orderliness of wheel alignment parameters along with wheel jumpiness is got. The air suspension system including turning system that is fit to a kind of passenger car whose body doesn't bear the weight of load directly is design independently. Then based on kinematics analysis the structure optimal design model is established with considering the side way displacement of the wheel's contacting ground point as the goal function and the optimization in allusion to the parameters of the direction structure of air suspension is carried based on genetic arithmetic. Finally the relative reasonable project for the air suspension system is got.The dissertation analyses the air spring and spring bracket which belong to the air suspension system as pivotal components taking use of the finite element theory and method. The remodeling design fit to a kind of new passenger car is carried based on the mechanical characteristic analysis in allusion to the spring bracket of the air suspension system of the referenced passenger car. And the fatigue life of the spring bracket is calculated referencing the fatigue life calculation method of vehicle bridge used in the independent suspension. The stiffness characteristics, frequency characteristics and damper characteristics of air spring are analyzed. Considering the nonlinear features of the air springs in materials and geometry, the nonlinear finite elements analysis technology is used to build the finite element model of air spring and analyze the characteristics of air springs which are composed of composite materials. The deformation characteristics under different loads of air springs and different curtain-line angles are obtained. This provides some basis for the design of air spring.The dissertation divides the research object into several subsystems based on virtual prototype technique, builds the multi-body dynamics model of the whole vehicle which is designedindependently, designs the road characteristic files, carries the simulation of comfortable capability and compares the experiment results with the referenced passenger car and the vehicle which isn't equipped with air suspension. Through comparison the acceleration value of the relevant locations of the body is near to the referenced passenger car while less than the vehicle which isn't equipped with air suspension. This result indicates the vehicles equipped with air suspension has better comfortable characteristics than the vehicles not equipped with air suspension. The method can forecast the performance of the vehicles effectively during the process design moment and before manufacture. So most problems will be discovered before manufacture.The dissertation builds the geometrical and mechanical relationship of the main functional parts of the air spring suspension system of a kind of passenger car taking use of the similarity theory. Then the similarity models of the direction structure, the spring bracket, the damper equipment and air spring are built according to respective scale. Finally the multi-body dynamics similarity model is established under virtual environment and experiments are carried in allusion to the similarity system. The results are compared between the similarity model and former suspension model. The comparison result proves the feasibility of similarity modeling of suspension design.In the dissertation the research on the pivotal technology of air suspension and the theory and design method of vehicles has important guidance significance and practicality value to strengthen the independent exploitation capability and shorten exploitation cycle of the vehicles effectively.