Air springs can be divided into three types: bladder type, membrane type and composite type according to the structure of the airbag.
1) When the volume of the air chamber is the same, the more the number of curvatures of the airbag, the smaller the spring stiffness, but if the number of curvatures is too large, the lateral stability of the spring is not good. The effective area change rate of the bladder air spring is large and the spring stiffness is high. Therefore, the method of increasing the auxiliary air chamber is usually used to reduce the spring stiffness. At higher pressures, increasing the auxiliary air chamber volume has a more pronounced effect on the spring rate, but this effect decreases with increasing volume. For the bag-type air spring, appropriate selection of the effective area change rate of the spring and the volume of the auxiliary air chamber can obtain the appropriate spring stiffness. The bladder-type air spring has a long service life due to the small curvature change of the rubber membrane during operation.
2) The effective area change rate of the membrane air spring is smaller than that of the bladder type, so in the absence of an auxiliary air chamber, a lower spring stiffness can be obtained. It controls the rate of change of the effective area by changing the shape and size of the piston to obtain a more ideal inverse S-shaped elastic characteristic curve. The bladder air spring is difficult to do. In addition, from the perspective of the spring sealing form, the membrane air spring can adopt the pressure self-sealing type, which has a simple structure and low cost. The service life of the membrane air spring is generally not as long as that of the bladder type. At present, the membrane air spring is still used more in the car.
3) From the structural point of view, the composite air spring is a type between the former two. It combines the advantages of the above two air springs and has a lower spring stiffness, but the manufacturing process is complicated.
