Automobile suspension automation is progressing rapidly, and both supply and demand are driving the popularity of air suspension

The automobile suspension is an important force transmission connection device between the body and the wheels.

Car suspension is the connection device between the car body (frame) and the wheels. Its main function is to transmit the torque between the car body and the wheels, such as support force, braking force and steering force, and to reduce the impact of rough roads on the car body. Absorbs vibrations caused by wheel movement, ensuring car riding comfort and reducing losses in cargo transportation. Usually the automobile suspension structure consists of elastic elements, shock absorbers and guide mechanisms. These three parts play the roles of buffering vibration, absorbing vibration and transmitting torque respectively.

Elastic elements and shock absorbers together constitute the suspension damping system and are the most important components in the automobile suspension system. The elastic element has a certain buffering effect, which can extend the impact time, reduce the force per unit time, and achieve a buffering effect. The shock absorber can absorb energy, convert the kinetic energy of the impact into heat energy, and consume the excess vibration, thereby achieving the vibration reduction effect. The elastic element and the shock absorber are generally placed in parallel. During the compression and rebound process of the elastic element, the shock absorber absorbs energy at the same time. After that, the elastic element returns to its original length and supports the vehicle to its normal height.

Suspension systems undergo the evolution from passive suspension to active suspension

Suspension can be divided into passive suspension, semi-active suspension and active suspension according to different working principles. The stiffness and damping of passive suspension cannot be adjusted. The stiffness and damping coefficient of the suspension are set at the factory. It is difficult to adapt to different road conditions, and the ride comfort and stability are poor. However, the structure is simple and the cost is low, and it is usually mainly used in low-end models. Common solutions include coil springs and passive shock absorbers. In the late 1980s, semi-active suspension, which mainly uses passive control technology to change suspension damping, became mature. Semi-active suspension can change one of the damping and stiffness. There are two main products: one is the damping variable shock absorber, which can change the damping of the system at any time through the residual value of the vehicle body vibration, offset the vehicle body disturbance, and improve the riding comfort. sex. The second is the air spring, which can change the stiffness of the vehicle without changing the damping. Vehicles equipped only with air springs are mainly vehicles with higher load capacity requirements, such as pickup trucks and vans.

Active suspension can effectively improve user comfort and is the current development direction. The concept of active suspension was proposed by General Motors in the United States in 1954. On the basis of passive suspension, it adds adjustable stiffness and damping control devices, allowing the car to adapt to different loads, road conditions, and operability requirements.

There are three main goals of the automobile suspension system: reducing the vertical acceleration of the vehicle body, dynamic deformation of the suspension and dynamic load of the tires. Active suspension can take into account the car's ride comfort and operational stability. When the road environment changes, active suspension can adjust parameters such as stiffness and damping to maintain the distance between the body and the ground at a reasonable height, thereby improving the ride comfort and stability of the car and reducing wheel load fluctuations. Usually the elastic component uses an air spring and requires an energy input device for adjustment. Active suspension has a complex structure and high weight, and its active adjustment parameters consume high energy and cost. At present, the main difficulty of active suspension lies in the mechanical system, which needs to provide large driving force in a small space and ensure high frequency of chassis debugging. There are relatively few domestic products and low maturity. Most products can only solve the smoothness below 5Hz, and some BBA products can cover 20Hz. On the other hand, the difficulty lies in the control logic.

Air suspension is widely used in commercial vehicles, and the passenger car field is positioned in the high-end market

Commercial vehicle air suspension is more stable and comfortable than traditional suspension. Early air suspensions did not introduce electronic control systems, and were commonly installed on commercial vehicles such as trucks, tractors, and buses in European and American countries. For commercial vehicles, air springs are usually used to replace steel coil springs or air suspensions with steel leaf springs as elastic elements in order to obtain larger up and down strokes and more uniform axle loads than leaf springs, effectively protecting the axles and The air suspension is lighter than the leaf spring, which improves the vehicle's load-bearing capacity and driving stability. At the same time, the air suspension can soften the impact force on the car, reduce vibrations to optimize the driving experience, and protect cargo from damage by strong vibrations. The new version of "Technical Conditions for Motor Vehicle Operation Safety" GB7258-2017 released in 2017 proposed for the first time that the rear axle of dangerous goods transport vehicles with a total mass of 12,000kg or more, and all dangerous goods transport semi-trailers, three-axle fence type, and warehouse gate type semi-trailers The trailer should be equipped with air suspension.

Passenger cars are usually equipped with electronically controlled air suspension (ECAS), which is currently mainly targeted at the high-end market. The air suspension used in passenger cars is a type of electronically controlled active suspension. In 1957, the first passenger car model equipped with air suspension, the Cadillac Eldorado Brougham, was born; in 1962, Mercedes-Benz launched a self-developed air suspension system and installed it on the 300SE model code-named W112; in 1986 , Toyota introduced an electronic control system and active active adjustment function to the air suspension for the first time, and installed it on the Supra (A70) model. Starting in 1992, Land Rover's first-generation Range Rover (parameters | pictures) began to be equipped with a mature electronically controlled air suspension system (ECAS).

The vibration reduction structure of electronically controlled air suspension (ECAS) is relatively complex. In addition to air springs and variable damping dampers, it also includes a complete air supply system (air compressor, air tank, air valve, etc.) and corresponding Vehicle ECUs, sensors, etc. When the air suspension system is working, the ECU detects the height of the vehicle body in real time through the height sensor and obtains the vertical acceleration of the vehicle body, and at the same time detects the vehicle's driving speed through the speed sensor. Several index heights and multi-level adjustable damping values are stored in the ECU, and the air compressor stores compressed air in the air storage tank. The ECU compares the height sensor detection results with the index height. If the height difference exceeds the set range, the air valve group will be activated and the actual height will be adjusted to the index height by filling and deflating the air tank. The electromagnetic shock absorber performs corresponding damping force according to the vehicle body height, driving speed and acceleration, thereby meeting the requirements of car driving smoothness and ride comfort.

The air suspension system has obvious advantages, but its application scope is limited by cost and technology.

The advantages of electronically controlled air suspension (ECAS) for passenger cars are that the vehicle height, damping, and stiffness are adjustable, and the suspension state can be flexibly changed according to different road conditions and usage requirements. The height of the vehicle body can be actively adjusted to adapt to different road driving conditions. According to different road conditions or active input signals, the ECU controls the air compressor and exhaust valve to automatically compress or extend the spring, thereby lowering or raising the chassis ground clearance. For example, when driving at high speed, the chassis and body height are lowered to reduce wind resistance; when driving off-road or passing complex road sections, the body height is raised to protect the chassis and improve passability on complex road sections. In addition, the air suspension can also keep the height of the vehicle body constant at different loads through manual input signals, or the height of the front and rear axles can be adjusted individually to meet the needs of passengers and cargo.

The air suspension shock absorber realizes continuously adjustable damping and flexibly changes the softness and hardness of the suspension. Compared with traditional suspension, air suspension shock absorbers can adjust the damping size. The greater the damping, the stiffer the suspension system, making it easier for the vehicle to maintain the body posture, reduce cornering roll, and better vehicle handling performance; the smaller the damping, the softer the suspension system, and the smaller the vibration transmitted to the body. Comfort has been improved. The air suspension monitors road conditions in real time through sensors such as vehicle speed and steering, and adjusts the damping and stiffness of the suspension to meet different requirements for comfort and maneuverability in different situations. There are two main adjustment methods. One is to change the structure of the shock absorber, add a solenoid valve between the piston or the inner and outer chambers of the shock absorber, and control the valve opening to change the resistance to the internal liquid flow when the shock absorber is working, thus changing the Damping size. The other is to change the shock absorber oil by adding an electromagnetic coil to make the shock absorber oil magnetic. After the electromagnetic coil is energized, the magnetic field force generated by the electromagnetic coil will change the resistance of the shock absorber oil, thereby changing the damping.

The air spring has lower stiffness and is adjustable for a more comfortable driving experience. Suspension bias frequency is directly proportional to spring stiffness and inversely proportional to sprung mass. The smaller the offset frequency, the smaller the vehicle body vibration acceleration, and the higher the driving comfort. Air springs have an "reverse S"-shaped stiffness curve that can maintain a low stiffness value near the rated load. At the same time, the air spring can adjust the stiffness by changing the gas pressure, keeping the bias frequency at a smaller stable value and improving driving comfort. In addition, by introducing multi-chamber air springs, different air chamber combinations can change the air spring volume to achieve a larger stiffness adjustment range.

Driven by multiple factors such as localization and new energy, prices have dropped to open up incremental markets.

The European and American commercial vehicle markets are fully penetrated, while the domestic passenger car market penetration rate has large room for growth due to cost, technology and other factors. Air suspension has been restricted to high-end passenger cars for a long time. In traditional fuel vehicles, air suspension systems are limited to high-end models mainly for the following reasons:

1) The air spring sealing process is complex and the bladder manufacturing is difficult, so the cost of air suspension is very high. 2) The air suspension system is large and difficult to integrate into smaller passenger cars. System integration and lightweight technology require high additional development costs. 3) The early electronic control system was immature. The effectiveness of the electronic control system in adjusting the vehicle body height and shock absorber damping was not as effective as directly improving the suspension link structure or strengthening the chassis strength, and it also required the consumption of fuel vehicle power.

In terms of penetration rate, the European and American markets started early and have high penetration, and there is still room for significant improvement in the domestic market penetration rate. The development of air suspension business in the European and American commercial vehicle markets started early. Because air suspension can soften the impact force on the car, reduce vibrations to optimize the driving experience, and protect cargo from damage by strong vibrations, it has gradually become popular in the field of buses, buses and trucks. According to China Commercial Vehicle Network, as of 2020, the penetration rate of air suspension in the European and American heavy-duty truck market can reach 80%, and the penetration rate of air suspension in the trailer market can reach 40%. In the passenger car market, according to data released by the European Automobile Manufacturers Association (ACEA), European car sales in 2021 will be 11.775 million vehicles. Among traditional fuel vehicles on sale in China, only luxury cars priced above 700,000 yuan were equipped with air suspension systems. In recent years, some new energy vehicle manufacturing forces have lowered the price of air suspension models to the mid-to-high-end market range. However, the domestic air suspension market is still in its infancy, and there is still room for significant improvement in the overall penetration rate.

Domestic cost reduction, consumption upgrading and electrification development have driven increased demand for air suspension

Domestic manufacturers have obvious cost advantages in parts and components. Compared with imported original parts, the purchase unit price of domestic air suspension system-related parts will be significantly lower due to lower R&D costs due to reduced added value due to mature technology, as well as lower tariffs and transportation costs. Take the Mercedes-Benz S-Class air suspension parts as an example. According to quotations from relevant dealers, the price of the original OEMW220 front air suspension shock absorber assembly imported from Germany is about 2,250 yuan, while the market price of the same model of domestic accessories is about 1,600 yuan. , about 30% lower than imported parts. In addition, the original disassembled unit price of the Continental air compressor equipped with the fourth-generation Land Rover Discovery is 1,500 yuan, and the price of the complete air supply unit is about 2,000 yuan. The price of similar products developed by AMK Company acquired by Zhongding Group is about 1,200 yuan. Yuan. After its technology is introduced into the domestic compressor production line, the purchase price of the domestic air supply unit can be reduced to about 1,700 Yuan.

Under the trend of accelerating localization, the price of the complete air suspension system will drop to less than 10,000 yuan. Currently, the entire imported air suspension system on the market is worth about 12,300 yuan. The first component to be localized was the air spring. After localization, the price of the component was reduced by 25%, and the price of the complete vehicle package of the air spring was reduced from 4,000 yuan to about 3,000 yuan. After the air compressor and air supply unit are domestically produced, the price of the air supply unit will be reduced from about 2,200 yuan to about 1,700 yuan. With the subsequent localization of variable damping shock absorbers, air suspension control systems and ECUs, we estimate that the value of a domestic air suspension system bicycle will be reduced to less than 9,500 yuan, which is about 25% lower than the imported air suspension system. Currently, the lowest-priced model equipped with imported air suspension on the market is Ji Krypton 001 (the air suspension supplier is Vibach). The reference price of the lowest model equipped with air suspension is 319,000 yuan. The domestic air suspension system corresponds to the complete vehicle sales. The price may drop to the range of 200,000-300,000 yuan.

The demand for air suspension in new energy vehicles is growing. On the one hand, new energy vehicles are more sensitive to cruising range, and air suspension can improve their cruising range to a certain extent. When new energy vehicles drive at high speeds, they need to consume a lot of energy to fight against wind resistance. Air suspension can adjust the height of the car's chassis to reduce the wind resistance of new energy vehicles. According to NIO ET7 data, its active air suspension can optimize air resistance by about 0.7%, increasing the cruising range by 1.6km. On the other hand, new energy vehicles are heavier and traditional suspension affects the driving experience. Affected by factors such as battery weight, new energy vehicles are generally heavier than fuel vehicles. At the same time, the weight of new energy vehicles is gradually increasing. If coil spring suspension is used, the diameter of the steel wire will be very large, which will affect the design and driving of the vehicle. Comfort. Air suspension can effectively balance high load-bearing and comfort requirements.

Consumption upgrades have brought about increased demand for air suspension. In recent years, the sales volume of domestic luxury independent brand passenger cars has grown significantly, and Chinese consumers have a clear trend of upgrading their consumption. The development of domestic brands towards high-end needs comprehensive improvements in multiple areas such as cockpit, smart driving, and chassis. As one of the important components of chassis upgrades, air suspension has also become an important direction for some OEMs to improve product comfort. At present, air suspension is gradually penetrating into models in the range of 300,000 to 400,000 yuan, which is significantly lower than the previous brand models with 700,000 yuan and above. It is in line with the price range of independent high-end brands and brings a broader market space.

China’s passenger car air suspension market is expected to grow rapidly in 2025

The size of China's passenger car air suspension market is expected to grow rapidly in 2025. The penetration rate of air suspension in 2021 is limited by factors such as cost, technology, and production capacity, and is still at a low level. We estimate that the penetration rate is 2.9%, which corresponds to the overall market size of passenger car air suspension being approximately 9.18 billion yuan. As the localization of core components accelerates, the cost of air suspension will be significantly reduced, and the average bicycle value of the air suspension system is expected to drop by more than 40%; at the same time, as local manufacturers’ production lines are put into production and the number of adapted models increases, the air suspension The market size is expected to grow rapidly in the coming years. We predict that the overall penetration rate of air suspension will reach 15% in 2025, the market size is expected to reach 31.4 billion yuan, and the CAGR from 21 to 25 will reach 36%.

Technical barriers to upstream parts are obvious, and “split procurement” opens up space for the midstream industry

my country's local suppliers are mainly concentrated in the upstream parts manufacturing field, and a large number of new energy OEMs have joined the downstream industry. Looking at the comprehensive air suspension industry chain, local suppliers have achieved a lot in the upstream.