A high-quality SUV must have both the comfort of a car and the passing performance of an off-road vehicle. The air suspension system is the best choice to achieve this goal. According to the road conditions and the signal of the distance sensor, the trip computer will determine The height of the vehicle body is changed, and then the air compressor and the exhaust valve are controlled to automatically compress or extend the spring, thereby reducing or raising the ground clearance of the chassis to increase the stability of the high-speed vehicle body or the passability of complicated road conditions.
Air springs can be divided into three types: bladder type, membrane type and composite type according to the airbag structure. 1) When the air chamber volume is the same, the more the airbag curvature is, the smaller the spring stiffness is, but there are too many curvatures, and the spring lateral stability is not good. A bladder air spring has a large effective area change rate and a high spring stiffness. Therefore, an auxiliary air chamber method is usually adopted to reduce the spring stiffness. At higher pressures, increasing the volume of the auxiliary air chamber has a more significant effect on spring stiffness, but this effect decreases with increasing volume. For a bladder air spring, proper selection of the effective area change rate of the spring and the volume of the auxiliary air chamber can obtain an appropriate spring stiffness. Capsule air springs have a small change in the curvature of the rubber film during operation, and the spring has a long service life.
2) The effective area change rate of the membrane air spring is smaller than that of the capsule type, so in the absence of an auxiliary air chamber, a lower spring stiffness can be obtained. It controls the effective area change rate by changing the shape and size of the piston to obtain a more ideal inverse S-shaped elastic characteristic curve. The capsule air spring is difficult to achieve. In addition, from the perspective of the spring sealing form, the membrane air spring can adopt a pressure self-sealing type, which has a simple structure and low cost. Diaphragm air springs generally have a longer service life than capsule airbags. At present, membrane air springs are more commonly used in automobiles.
3) From a structural point of view, a composite air spring is a type in between the first two. It combines the advantages of the above two air springs, has a lower spring stiffness, but has a complicated manufacturing process.
Generally speaking, models equipped with air-adjustable suspension are equipped with ground clearance sensors near the front and rear wheels. According to the output signal of the ground clearance sensor, the trip computer will determine the change in vehicle height and control the air compression. The engine and the exhaust valve make the spring automatically compress or extend, thereby reducing or raising the ground clearance of the chassis, in order to increase the stability of the high-speed body or the passability of complicated road conditions. In daily adjustment, the air suspension will have several states. 1. Keep it up. When the vehicle is lifted by the lifter and leaves the ground, the air suspension system will close the relevant solenoid valve, and the computer memorizes the height of the vehicle body, so that the vehicle will maintain the original height after landing. 2. Normal state, that is, the running state of the engine. During driving, if the vehicle height changes beyond a certain range, the air suspension system will adjust the vehicle height at regular intervals; 3. Wake state. When the air suspension system is awakened by a remote control key, door switch or luggage compartment lid switch, the system will check the vehicle height via the vehicle level sensor. If the vehicle height is lower than normal to some extent, the air tank will provide pressure to raise the vehicle to normal height. At the same time, the air suspension can adjust the soft hardness of the shock absorber, including three states: soft, normal, and hard (also marked as comfortable, normal, sports, etc.). The driver can use the control buttons in the car to perform control. Of course, compared with traditional suspensions, because the air-adjustable suspension structure is more complicated, its probability and frequency of failure will be higher than that of the coil spring suspension system, and air is used as a power source for adjusting the height of the chassis. Sealability is also a problem. In addition, if the height of the chassis is frequently adjusted, it may cause local overheating of the air pump system, which will greatly reduce the service life of the air pump. Of course, with the continuous improvement of technical level, many problems have been well resolved, and at the same time, the models used are becoming more and more widespread.