Air Suspension System is a technology that adjusts the body height and stiffness of the suspension system by adjusting the air pressure inside the air springs. It can better adapt to road conditions and different driving states, thus enhancing vehicle comfort and handling. Compared with fuel vehicles in the same class, the vehicle weight of electric vehicles is heavier, the center of gravity is also more rearward, and the initial power torque is larger, these factors make the performance of the entire vehicle suspension put forward higher requirements. Especially in new energy vehicles, the weight of the power battery increases the spring mass of the vehicle body, and the air suspension can optimize the airflow underneath the vehicle body to achieve a better cooling effect of the battery while reducing the impact on the road surface. With the gradual improvement of the level of vehicle intelligence, the combination of the vehicle’s sensing ability and innovative suspension technology can pre-judge the road conditions and actively adjust the vehicle for better comfort and maneuverability in the driving process, so the air suspension is gradually becoming an important incremental configuration for mid-range and high-end passenger cars.
1. Introduction of Air Suspension System
An air suspension system consists of several key components, including air springs, air supply units (e.g., air compressors, tanks, distribution valves, etc.), electronic control units (ECUs), and various types of sensors (body height sensors, acceleration sensors, etc.). Air springs are usually used in conjunction with variable damping dampers, with the air compressor and air springs being the highest-value components in the system with the highest technical barriers. The main function of air suspension is to adjust the suspension stiffness and body height by controlling the air pressure of the air spring according to the road conditions and driving needs, which ultimately improves the comfort and stability of the whole vehicle. In practice, air suspension systems are widely used in various types of vehicles, especially luxury sedans and high-end electric vehicles. The main purpose of its application is to improve the dynamic response of the vehicle, and enhance the comfort and maneuverability of the vehicle in complex road conditions.
2. the key component air spring
Air spring is the core component of the air suspension system, using the reaction force generated by the air pressure inside the rubber airbag as the elastic restoring force. The air spring can adjust the height of the body and suspension stiffness by adjusting the air inside the airbag. At the front, the air spring and damper are usually fitted as a single unit, while at the rear, the air spring and damper are usually arranged separately. The compressed air inside the air spring makes it an adjustable elastic element, capable of varying its stiffness according to the different needs of the vehicle for an optimal driving experience.
1. Body height adjustment: By inflating the airbags, the ground clearance of the vehicle can be raised to enhance the vehicle’s passability; and by deflating the airbags, the height of the vehicle will be lowered, thus improving stability at high speeds, reducing wind resistance, and improving driving economy.
2. Comfort and Load Adaptability: The non-linear stiffness of air springs enables them to maintain a comfortable driving experience under different load conditions. When the vehicle load changes (e.g. no load vs. full load), the air spring can adapt by adjusting the initial stiffness to maintain consistent driving comfort.
3. Vibration suppression: The rubber air bladders of air springs effectively isolate high-frequency vibrations and noise from the road due to their material properties. The vibration-absorbing properties of the rubber material and the air itself give it better sound insulation properties, making the interior environment quieter and more comfortable.
3. the technical barriers of the air spring
Air spring is the core of its rubber bladder design and manufacturing process. The durability of the bladder directly determines the service life of the air spring. Air springs in different working conditions repeatedly lift, and vehicles are often in high or low temperature extreme environment, these will be on the durability of the rubber bladder put forward very high requirements. The bladder skin consists of an inner rubber layer, an outer rubber layer, a cord layer and a wire ring vulcanized.
1. Inner and outer rubber layers:
The inner and outer cladding are made of high-performance rubber with excellent weather and oil resistance. The inner cladding is particularly important because it is directly related to the sealing of the gas spring.
2. Cord Layer:
The main part of the air spring load support is the cord layer, which usually consists of two layers of support bodies arranged in a cross pattern. These cord materials play a decisive role in the durability and compression resistance of the gas spring, and the design of the cord ensures that it maintains excellent resistance to rupture even under high bending conditions.
3. Wire coils:
At the open ends of the two flanges of the gas spring capsule, wire coils are vulcanized and fixed to ensure that there is no air leakage. The wire coils must be designed to maintain their sealing and firmness over a long period of time. The development of air springs requires the accumulation of a large number of samples and experimental verification. From the development of the rubber formulation to the optimization of various parameters in the vulcanization process, repeated experiments and verification of the final solution through a large number of fatigue tests are required. Especially in the assembly process, the buckling process is a technical difficulty that directly affects the performance of the air spring. Therefore, the durability, sealing and noise control of the bladder become the key technical barriers for air springs, especially for high-end luxury brands, the requirements for these performance indicators are even more stringent.
4.Types and Development of Gas Springs
There are three main types of air springs used in automobiles: single-chamber, dual-chamber and triple-chamber. These types of air springs vary in structural complexity and performance.
1. Single Chamber Air Spring
Single-chamber air spring is the most common type in the market. It has only one chamber, relatively simple structure and process, and low cost, so it is widely used in the air suspension system of domestic passenger cars. Single-chamber air springs can adjust the body height during inflation and deflation, but due to the limited variation of the force area inside the chamber, their stiffness adjustment range is relatively small, and they can’t provide a richer driving experience.
2. Dual chamber air springs
Dual-chamber air springs are based on single-chamber air springs with an additional air chamber, which is separated into two working chambers by a solenoid valve. Compared to single-chamber, dual-chamber air springs can be switched between different driving modes. By adjusting the fitment of the main chamber and the secondary chamber, the vehicle is able to flexibly switch between sporty and comfortable, thus meeting more diversified driving needs. Due to their more complex structure and higher manufacturing costs, dual-chamber air springs are mainly used in high-end vehicles. 
3. Triple Chamber Air Springs
Triple-chamber air springs go further than double-chamber air springs by realizing four different stiffness levels through three internal chambers and two solenoid valves, which provides a better overall performance. There are not many passenger cars equipped with three-chamber air springs on the market, mainly focusing on some luxury brand models, such as Porsche Cayenne and Mercedes-Benz GLC.
5. Market pattern of gas springs
The global market for air springs is mainly occupied by overseas suppliers such as Continental, Vibracoustic and Firestone. These suppliers have a deep accumulation of rubber product manufacturing technology, occupying a large share of the air spring market. However, in recent years, domestic suppliers such as KH Automotive and Baolong Automotive have made breakthroughs in the development and production of air suspension systems.
1. Overseas suppliers
– Continental AG, Germany: Continental entered the air suspension field as early as in the early 2000s, providing air suspension systems for luxury brands such as Audi and Volkswagen, with production capacity in Germany, Hungary, Romania and China.
– Vibracoustic: As a subsidiary of Freudenberg, Vibracke has a leading global market share in the field of air springs, especially in the core technology of spring skin material. Its products have comprehensive coverage of air suspension systems, air springs, sensors, compressors and so on.
– Firestone: Firestone’s air spring products also have a high market share in China, especially in the field of commercial vehicles and buses.
2. China Suppliers
– KH Automotive: Established in Huzhou, Zhejiang Province, Konghui Technology specializes in the R&D and production of automotive electronically controlled suspension systems. The company has made significant progress in air suspension systems and air springs, especially in the supply chain of emerging domestic EV brands.
– BaoLong Automotive: BaoLong Technology is an auto parts company headquartered in Shanghai, which has gradually realized large-scale mass production in the field of air springs through product development and market expansion.
– Tuopu Group: Tuopu Group has also invested a lot of resources in the research and development of air suspension systems and gradually realized mass production, and has become an important partner of a number of mainstream automobile manufacturers at home and abroad.
6. the development trend of air springs
As the automotive market for ride comfort and handling performance requirements continue to improve, the application of air springs in vehicles has become more widespread. The future development trend of air springs is mainly reflected in the following aspects:
1. multi-chamber structure: from single chamber to dual chamber and even multi-chamber, the structural design of air springs is becoming more and more complex, and this change is aimed at providing a greater range of stiffness adjustment, thus providing better adaptability to different driving modes.
2. Intelligent Adjustment: Air springs are integrated with vehicle intelligence systems, which utilize sensors and ECUs to collect real-time vehicle driving data and actively adjust the air pressure of air springs to cope with different road conditions and improve vehicle comfort and handling.
3. Lightweight and Durability Improvement: With the tightening of environmental regulations, the lightweight and durability of air spring materials have become the focus of research and development. By improving rubber formulations, cord materials and manufacturing processes, companies strive to reduce the overall weight of air springs while ensuring high performance.
The air suspension system realizes changes in body height and suspension stiffness by adjusting the air pressure inside the air springs, enabling the vehicle to better adapt to different driving conditions and road situations, and improving overall ride comfort and handling. Compared with traditional coil springs, air springs have adjustable non-linear stiffness characteristics, which can be adjusted according to the load and driving needs, and are suitable for electric vehicles and other vehicles that require higher suspension performance. With the continuous breakthroughs of domestic and foreign suppliers in the field of air suspension, the application scope of air springs will be further expanded, especially under the impetus of the trend of intelligentization and electrification, air suspension is expected to become an important part of the future automotive suspension system. Domestic enterprises are gradually making progress in technology accumulation and market share, and local suppliers are expected to occupy a more important position in the air suspension market in the future.
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