What is an air spring?
An air spring is a mechanical component that utilizes compressed air to generate elasticity. Widely used in various fields such as automobiles, construction machinery, and aerospace, it primarily functions to provide suspension, support, cushioning, and adjustment. Its structure differs from traditional metal springs; instead of metal, it stores energy and generates reactive forces using gas. Air springs regulate their hardness and height through inflation and deflation of a sealed airbag.
Why use air springs?
Adjustability
The hardness and height of air springs can be adjusted by changing the air pressure inside the airbag, providing high adjustability. Hence, air springs can adapt to various loads and operating conditions.
When air is pumped into the airbag, the pressure increases, leading to increased hardness and height. Conversely, when air is released, the pressure decreases, reducing hardness and height. For example, in off-road conditions, increasing air pressure can enhance suspension and traction.
Comfort
Compared to traditional metal springs, air springs offer better comfort. They adjust suspension hardness in real-time based on road conditions and loads, reducing bumps and vibrations, thereby enhancing driving comfort.
This adaptability is particularly noticeable on rough roads. While many traditional metal springs are also adjustable, they often lag behind air springs in comfort.
Adaptability
Because air springs can be adjusted according to specific needs, they can accommodate various loads and road conditions. Whether used in heavy-duty trucks or passenger vehicles, they offer excellent load-bearing performance.
Lightweight
Most air springs use rubber materials and have a simple structure, making them lighter than traditional springs. This helps reduce vehicle weight, improving fuel efficiency and overall vehicle performance.
Durability
Air springs use high-strength alloys for metal parts and rubber or polyurethane materials for airbags, providing good fatigue resistance and corrosion resistance. They perform well under extreme conditions and harsh environments. For example, in complex terrains for off-road vehicles or prolonged exposure to corrosive seawater for ships, air springs maintain long-term durability.
Noise Reduction
Air springs effectively reduce noise because they obtain elasticity through compressed air rather than compressing metal like traditional springs. Therefore, they can better reduce road noise and vibration transmission, effectively maintaining interior quietness, which is crucial for luxury cars and premium SUVs.
The structure composition of air springs
As shown in the diagram, this is the internal structure composition of an air spring. While the structure may vary for different types of springs, their basic principles and functions remain the same. Let’s delve into its key components and functions.
Airbag
- Function: The rubber airbag can be considered the core component of an air spring. By inflating air into the sealed airbag, it generates pressure, thereby enhancing elasticity and support. The flexibility and compressibility of the airbag allow the air spring to effectively absorb vibrations and shocks.
- Material: Airbags are typically made of high-strength synthetic rubber or reinforced rubber. Sometimes, chloroprene rubber or fluoro rubber is used to enhance durability and corrosion resistance.
Air chamber
- Function: The air pressure inside the air chamber determines the hardness and height of the air spring. We can adjust the air pressure inside the air chamber to change the characteristics of the air spring to meet our needs.
- Structure: The air chamber is the sealed space inside the airbag, which can be divided into single or multiple compartments. The design of multiple compartments can further optimize the characteristics of the air spring, allowing its advantages to be better utilized.
End cap
- Function: The end cap is used to seal the two ends of the airbag. Since the airbag is relatively soft and cannot be directly connected to the vehicle or suspension system, end caps are needed as intermediaries for connection. The end cap also contains valves for inflating and deflating, used to adjust the air pressure inside the airbag.
- Material: Typically made of high-strength metal alloys (such as aluminum alloys, steel alloys) or high-strength plastics.
Inflation and exhaust valves
- Function: The main function is to inflate or deflate the airbag, controlling the air pressure in the air chamber to adjust the hardness and height of the air spring. These valves are connected to the electronic control system and can be adjusted automatically or manually.
Reinforcement layer
- Function: The reinforcement layer is embedded in the rubber airbag, similar to the steel bars in concrete during building construction. It provides additional strength and durability to the airbag, preventing it from bursting or deforming due to excessive air pressure in the air chamber.
- Material: Typically made of nylon, polyester, or woven steel wire.
Cushioning layer
- Function: The cushioning layer helps the airbag further absorb impacts and vibrations, thereby protecting the airbag and extending its lifespan.
- Material: It is made of soft materials and is usually attached to the exterior or interior of the airbag.
Positioning ring and support plate
- Function: The positioning ring ensures that the position of the airbag does not change during compression or extension, preventing displacement. The support plate provides additional support for the overall structure.
- Material: Typically made of high-strength alloys.
Working Principle of Air Springs
Basic Principle
The fundamental principle of air springs lies in utilizing the compressibility of air. When the air inside the airbag is compressed due to an impact, it provides a reactive force, thus mitigating the impact force. This reactive force is similar to the elasticity of traditional springs. The design of the airbag and the pressure of the gas determine the elasticity and damping performance of the air spring.
Load and Elasticity
When an air spring is impacted, the airbag is compressed, causing an increase in internal air pressure. According to Boyle’s law (P1V1=P2V2), when gas is compressed, its volume decreases and pressure increases. At this point, it exhibits elastic characteristics, capable of counteracting and buffering the impact. When the impact decreases, the air pressure decreases, the volume increases, and the airbag returns to its original state, awaiting the next impact.
Control System
Modern air springs are equipped with electronic control systems, which can precisely control and adjust the performance of air springs in real-time, including:
- Sensors: Real-time monitoring of vehicle height, load, and driving speed data.
- Electronic Control Unit (ECU): Automatically controls air compressors and valves in real-time based on sensor data to adjust the air pressure of the air spring.
- Manual control: You can manually adjust the hardness and height of the air spring through switches to meet your different driving needs.
Classification of Air Springs
Air springs are mainly classified based on their structure. Among the products available on the market, they can be roughly divided into the following three categories:
Bellows Type Air Springs
- Single bellows: Comprised of a single rubber or polyurethane airbag, it has a simple structure and is suitable for situations with small loads or limited space.
- Double bellows: Consisting of two airbags stacked vertically with a metal support plate in between for fixation, double bellows air springs can withstand larger loads and provide greater elastic travel, offering better shock absorption.
- Multiple bellows: Composed of multiple airbags, it offers better performance than single and double bellows types but occupies more space, typically suitable for heavy-duty vehicles and industrial equipment.
Rolling Lobe Air Springs
These air springs feature a bellows portion that rolls like a lobe, allowing it to be installed in tight spaces and providing greater elastic travel. Rolling lobe air springs are typically used in the suspension systems of passenger and commercial vehicles.
Convolute Air Springs
Utilizing rubber molds as the primary elastic component, the airbag stretches and contracts with the help of convolutes. Its compact structure makes it suitable for precision-controlled industrial applications such as shaker tables and precision machinery.
Are air springs better than coil springs?
Let’s compare the advantages and disadvantages of air springs and coil springs to help you understand them systematically, assisting you in choosing the most suitable suspension system for your needs.
Adjustability
- Air Springs: By controlling the pressure inside the airbag to adjust its height and hardness, air springs can adapt to various road conditions. They can also automatically adjust based on different road and load conditions to achieve the most comfortable ride. Therefore, air springs offer higher adjustability.
- Coil Springs: Their hardness and height are fixed and cannot be adjusted in real-time according to road and load conditions. Their performance varies significantly under different conditions. If the load exceeds their capacity, their inability to adjust may render them ineffective.
Comfort
- Air Springs: By compressing air to achieve damping effects, air springs can better absorb and alleviate vibrations and noise transmitted to the cabin, enhancing the comfort of driving and riding. They can also help vehicles maintain stability on different roads, reducing body sway and jolts.
- Coil Springs: While traditional springs can provide some damping effects, compared to air springs, they may prove inadequate in complex road conditions or with heavy loads, resulting in poorer shock absorption. This is especially evident in cases of heavy loads or high-frequency vibrations, where they may fail to absorb vibrations and noise effectively, leading to a poorer driving and riding experience.
Durability and Maintenance
- Air Springs: Due to the rubber airbag’s aging and wear over time, regular inspection and replacement are required. Additionally, air springs have a complex structure with many components such as airbags, air compressors, valves, and positioning rings, leading to higher maintenance costs.
- Coil Springs: Made of metal materials, coil springs have a simple structure and excellent durability, requiring less frequent replacement. Periodic checks for mechanical damage or deformation are usually sufficient, resulting in lower maintenance costs.
The above comparisons highlight the strengths and weaknesses of air springs and coil springs from various perspectives. Considering your own requirements along these dimensions can help you choose the most suitable shock absorber.
Design and Manufacturing of Air Springs
Now let’s delve into Vista Motion and understand how we turn your ideas into reality and what professional services we can provide for you.
Requirements Analysis and Specification Determination
This is the initial stage where you share your ideas with us. Our engineers can customize air springs tailored to your needs. We need to know:
- Application scenario: Specify where you intend to use the air springs, such as in vehicle suspension systems, industrial equipment, railway transport, etc.
- Load requirements: Determine the maximum and minimum loads the air springs need to support.
- Dimensional requirements: Specify the size of the air springs to avoid them being too large or too small.
- Travel requirements: Determine the extreme compression and expansion travel limits of the airbag.
- Environmental conditions: Consider factors such as temperature, humidity, and corrosion in the working environment of the air springs.
Material Selection
Based on your requirements, our engineers will select the most suitable materials for your air springs:
- Rubber materials: Choose the highest quality natural or synthetic rubber with high elasticity, wear resistance, aging resistance, and corrosion resistance. The rubber material also needs to undergo reinforcement to maximize its performance.
- Reinforcement materials: We will select high-strength fibers such as nylon and polyester as reinforcement materials for the airbag, enhancing its pressure resistance and wear resistance when combined with rubber.
- Metal components: For metal parts like end caps and support plates, we choose high-strength alloys or aluminum alloys. These components also need to undergo anti-corrosion treatments such as galvanizing or coating to ensure their high strength and corrosion resistance during long-term use.
Design and Simulation
- 3D design: Based on the requirements, we determine the shape and size of the airbag, such as diameter, length, and wall thickness, for 3D design. At this stage, we also need to consider the design of the bellows and diaphragms, ensuring smooth operation during contraction and expansion.
- Finite Element Analysis (FEA): After designing the 3D model of the air springs, we use FEA software to simulate its stress distribution and deformation under different loads and road conditions. Based on the simulated data, we further optimize the design to reduce stress concentration and material fatigue, thus improving the lifespan and performance of the air springs.
Manufacturing Process
- Rubber compounding: Mix rubber and other additives according to the formula, thoroughly blend them using a mixer, and then press the mixed rubber into rubber sheets of the required thickness using a calendaring machine.
- Reinforcement layer fabrication: Composite high-strength fiber materials with rubber to make multi-layer composite materials, which are used to enhance the strength and wear resistance of the airbag.
- Airbag molding: Place the composite material in the mold of the airbag, pressurize and vulcanize it using a vulcanizing machine to cross-link the rubber material and enhance its elasticity and durability. After vulcanization is complete, the initial shape of the airbag is obtained.
- Assembly: Assemble other pre-processed metal components such as end caps with the airbag through bonding or mechanical fixation, ensuring the airtightness of the air spring and the overall structure’s strength.
- Quality inspection: We conduct strict quality inspections on air springs, including airtightness testing, fatigue testing, pressure resistance testing, and a series of tests to ensure that the products delivered to you meet the requirements.
How to Maintain and Care for Air Springs
Regular Inspections
- Visual Inspection: You need to regularly inspect the appearance of the air springs, checking for cracks, wear, or deformations in the airbags. Also, ensure that end caps and connecting components are not loose, corroded, or damaged.
- Leak Inspection: You can use soapy water or specialized leak detection sprays to check for any air leaks in the airbags and connecting areas.
- Pressure Check: Regularly check the pressure inside the airbags to ensure it’s at a normal level. If any abnormalities are found, investigate promptly and make repairs as necessary.
Cleaning and Maintenance
- Surface Cleaning: Periodically clean the surface of the airbags with mild soapy water and a soft cloth to remove dirt, oil, or corrosive substances, ensuring the airbag surface remains clean. Avoid using chemical solvents and hard brushes as they can damage the airbags.
- Protective Treatment: If you use air springs in harsh environments, apply appropriate protective treatments to the surface of the airbags to extend their lifespan.
Regular Lubrication
- Lubricate Connecting Components: Regularly lubricate the connections between the air springs and the vehicle or equipment to ensure smooth operation and prevent excessive friction.
Conclusion
That wraps up the guide to air springs. We hope this article helps you gain a better understanding of them and potentially saves costs for your project or leads to better supplier choices. If there are any issues with this article, please don’t hesitate to contact us for corrections. We would greatly appreciate it.
