The Design Of Air Spring For Passenger Car

Since the emergence of semi active suspension technology carried with air spring, along with the rapid development of advanced technologies such as automotive electronics, measurement and control technology, material molding, mechanical process etc, the design and controlling technology of air spring also became matured gradually. During the development process of semi active suspension system, the development and design work of air spring shall occupy the important position. In this paper, starting from the rigidity design of air spring, it gives the detailed introduction of the rigidity design and matching process of air spring, and describes the structural design and system design of air spring, represents the testing process of the accessories of air spring, completes the operating stability and ride comfort test on the air suspension, fully interpret the matching development process of air system. Constitute as follows:The basic utilities of suspension is the scientific control on vehicle movement, including the control on the vehicle movement states such as vertical movement, inclining movement, pitching movement etc, based on the movement toward three directions to generate the relative technical indicator projects such as the vehicle power distribution and response rate etc, further to describe and evaluate the whole vehicle performance from different angles. Based on this point, to carry out the structure design of air spring, set up the dynamics model, to expound the rationality of rigidity match.For single air-tight air spring, the character of gas determines the changeable rigidity of air spring. While the load on the air spring becoming larger, the quantitative gas inside the container shall be compressed with increased gas pressure and spring rigidity; while the load on air spring becoming smaller, the volume of quantitative gas inside the container shall be increased with lowered gas pressure and reduced spring rigidity. Based on such basic characteristics, with the consideration of the conditions such as the volume, pressure, variable stiffness of the air spring, we can design the reasonable shape of air spring according to rigidity demand, achieving the effective volume change rate of air spring and the rigidity of aimed design. Through checking the air spring rigidity during design period through using the finite computing method, it proves the feasibility of air spring structure design.The air spring system consist of air spring, gas line structure component, height sensor, controlling unit(ECU), to control the vehicle height at the real time and the suspension rigidity of vehicle, and also realize the shift of vehicle working model. The height adjustment shall be the most important function of air spring system, it requires to keep the vehicle height at the preset level automatically. During the height adjustment period, it can calculate the aeration rate of air spring according the signal value of height sensor, so that to adjust the vehicle height by charging/ discharging the gas in/ from the air spring system. While the vehicle is stopped or driving, it can adjust the vehicle height at any time except the forbidden height adjustment on air suspension during the turning operation.To introduce the subjective evaluation, objective test and adjustment & matching links during the determination and breakdown process of the whole vehicle target, to decompose the whole vehicle performance. Through the subjective evaluation, it should use the professional drivers to give the systematical and detailed evaluation and summarize the pros and cons of the whole vehicle performance from the aspects of accelerating performance, breaking, turning, driving straightly, driving comfort etc during the development process, and adjust the relative structural components that influencing the performance by combining the results of both objective test and simulation computation. In this paper, it determines the matching test and verification outlines during the development process of air spring through such work and conduct the practice accordingly, completes the dynamic/ static rigidity test of air spring component and the whole vehicle frequency bias test, drive comfort test and operational stability test on the counterpart vehicle, benchmark vehicle, target vehicle, then to analyze the testing results, providing the effective reference for the coming engineer testing and certifying works.There's still no matching standards on the performance and reliability test of passenger car, air spring of semi active suspension, for the whole vehicle performance test on the vehicle equipped with semi active suspension system, it introduces the subjective evaluation method in the matching process between the air spring and whole vehicle characteristics indicators, explains the items of subjective test, expresses the requirement on the objective and subjective consistence. However, it may still need further study on how to represent such target through the target of whole vehicle development target and component indicator breakdown during the whole vehicle development process.