Development trend of air spring

With the rapid development of expressways in China and the increase of traffic volume, vehicles are required to have better handling stability, smoothness and safety, and will be widely used. In addition, with the further deepening of the research and understanding of the damage mechanism of heavy trucks to the pavement, and the government's attention to highway maintenance, the application of air springs in the heavy vehicle market will also be further increased. At the same time, the intelligent degree of automobile control system is becoming higher and higher, and the electronic control air spring will become the inevitable trend of future development.
Development of air springs for railway vehicles in China
Through years of efforts and exploration, the design and development level of air springs for rail vehicles in China has made a great breakthrough. The structural design is increasingly advanced and reasonable, and the types are increasingly rich. It has been widely used in railway passenger cars, subways, light rail and multiple units. In the future, with the continuous development of rail transit in China, the research and development of air spring should pay attention to the following aspects:
(1) Continue to research and develop the air spring applicable to the bogie of bolsterless passenger cars, especially strengthen the research and development of air spring for high-speed passenger cars and high-grade urban rail vehicles with a speed of 300 km/h and above;
(2) Improve the design and theoretical calculation level of air spring, and improve the accuracy of analysis and calculation by introducing internationally popular advanced design methods and using modern nonlinear finite element theory,
(3) Strengthen the in-depth research on the establishment of accurate dynamic calculation model of air spring, truly reflect the role of air spring suspension in vehicle dynamics calculation, improve the level of vehicle dynamics calculation in China, and give full play to the guiding role of dynamic calculation in vehicle design;
(4) Carry out the feasibility study of the air spring active control system, that is, change the existing altitude control system to the on-board microcomputer control system, and improve the control reliability;
(5) Strengthen the research on the localization of air springs for imported high-grade rail vehicles to make them meet the standard requirements of similar products in Europe, and provide reliable product guarantee for the localization of the whole vehicle and the manufacture of domestic vehicles;
At present, most heavy commercial trucks, trailers and buses in North America and Europe are equipped with air suspension, and the demand for air suspension in South America and Asia has been growing. Part of the reason for this trend is that the requirements of the market for commercial vehicles are becoming more and more complex. Vehicles should not only reduce the operating costs as much as possible, but also have high reliability, durability, safety and driving comfort. Compared with the traditional steel suspension structure, the air spring can better meet all the above requirements for vehicles.
The initial design concept of the air spring, in short, is to encapsulate the bearing air column in a container composed of rubber and cord fabric under the condition of following the structural principle of the tire. The cord fabric can support the air pressure strength, while the rubber can prevent air leakage and provide a protective shell.
In the past few decades, the design of air spring has been continuously improved. In essence, there are certain differences between membrane air spring and rotary curved air spring. At the beginning of the design, the revolving surface structure was adopted, and this structure is still widely used in some fields. Because the membrane air spring can meet the different requirements of various vehicles and only needs to adjust the corresponding piston structure, the membrane air spring is widely used in commercial vehicles at present. The cylindrical structure of the air spring can ensure its strong flexibility, which is crucial to improve the handling performance, driving performance, durability and driving comfort of the vehicle.
The material of the air spring itself is a decisive factor. The pressure change inside the air spring will produce extremely high temperature, so the synthetic materials used need to have excellent thermal conductivity. Firestone products are made of high-quality heat-resistant natural rubber. At the same time, rubber also needs to have good oil resistance, grease resistance, dirt resistance and ozone resistance. Even if it is exposed to sunlight, it will also affect the durability of rubber.
The geometry of the air spring is also important. The sealing membrane needs to be able to maintain the metered air volume under different pressures. By adjusting the thickness of the membrane wall, the comfort and durability can be greatly improved. Generally speaking, thinner wall thickness can bring faster and smoother response time and better driving comfort, but it will also affect the durability of the adhesive film to a certain extent. The strength of the rubber film can be increased by adding a fiber layer. The linear structure in the fiber layer can be woven along the axial (warp) direction, or the cross structure can be used for weaving. The axial braided structure can reduce the wall thickness, but usually requires additional restraints to prevent the airbag from bursting due to excessive expansion.
The rubber airbag structure helps to form a seal and prevent air leakage. The integrated fiber mesh strengthens the strength of the air spring, making it able to resist the load generated by changing the air pressure; However, in order to better control the pressure, a piston is required for the air spring.
The force from road collision or load will cause the seal sliding piston to compress the air in the air spring. During compression, the rubber airbag rolls on the piston. Once the force disappears and the pressure is released, the air spring can recover to the minimum height designed in advance.
One of the main advantages of air suspension system is that it has automatic leveling function. Mechanical suspension, that is, leaf spring, cannot provide the best driving experience. Unlike steel substitutes, the air spring does not need static spring travel to compensate for load changes, but keeps the vehicle at a constant driving height by increasing or decreasing the air pressure in the rubber airbag. This means that the load, air inlet and headlamp position remain at standard levels. Additional comfort can be obtained without static spring travel. When the air spring is in the "design state" (that is, when the spring is at the best driving height), its natural frequency is much lower than that of the steel spring. The natural frequency of any object is its natural vibration frequency. A lower frequency means higher comfort for the driver, which in turn has a positive impact on health and productivity.