Automobile

Understanding air suspension system

An air suspension system is made up of an air spring, also known as plastic/airbags, rubber, and an airline system, all of which are coupled to an air compressor, valves, solenoids, and electronic controllers. The application of an air suspension system includes heavy-duty trucks, trailers, and buses.

In this article, you’ll get to know the definition, applications, diagram, components, construction, types, working, advantages, and disadvantages of the air suspension system. You’ll also learn about the parts and characteristics of air springs.

What is an air suspension system?

Air suspension is a type of vehicle suspension that is operated by an air pump or compressor that is either electric or engine-driven. The air is pumped into a flexible bellow, which is commonly composed of textile-reinforced rubber. Unlike a hydropneumatic suspension, which has many of the same benefits, air suspension uses compressed air rather than pressurized liquid. The bellows are inflated by the air pressure, which lifts the chassis away from the axle.

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What is an air spring?

In air suspension systems, air springs are used. Air suspension systems are installed and configured differently for different makes and models, but the essential idea is the same. The metal spring (coil or leaf) is removed, and an airbag, sometimes known as an air spring, is fitted or built to replace it. The suspension can be changed up or down when air pressure is delivered to the airbag (lifted or lowered).

Air springs are flexible bellows that contain the compressed air and are used to carry the load on automobiles. They are commonly composed of textile-reinforced rubber. The bellows are inflated by the air pressure, which lifts the chassis away from the axle. When compressed, air springs have flexibility or “springiness.” It’s found on a lot of today’s heavy-duty trucks, trailers, and buses.

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Characteristics & some benefits of air spring

  • When the vehicle is not loaded, they are soft, but as the load is raised, the stiffness improves by increasing the air pressure inside the chamber. As a result, when the vehicle is lightly loaded or completely loaded, it provides the best ride comfort.
  • Whenever the load varies, the air pressure is varied to keep the vehicle’s height constant.
  • By absorbing road shock, air springs improve vehicle stability.
  • Air spring systems are made to increase load-carrying capacity, stability, and overall ride quality.

Types of air spring

The following are the various types of air springs used in air suspension systems:

Double-Convoluted Air Spring:

The double-convoluted design resembles two little tires stacked on top of each other. These air springs have a higher load capacity, a shorter stroke, and a more progressive spring rate, making them ideal for most front suspensions where the spring lies well inboard of the suspension’s load point. As a result, load capacity needs are multiplied while travel requirements are divided.

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Tapered-Sleeve & Rolling-Sleeve:

Air springs with a tapered or rolling sleeve have a smaller diameter, a longer stroke, and a more linear spring rate. Because they have more travel needs and fewer load-capacity requirements, they are best suited for most back-end applications.

In air spring suspensions, devices for adjusting air pressure and compressors for compressing air are necessary. Small, electric, or engine-driven air compressors are commonly used in these systems, which occasionally fill an onboard air receiver tank that reserves compressed air for immediate use in the future. The suspension system, on the other hand, is more complicated. In current automobiles, electronically modulated air suspension is used in conjunction with air springs.

Read more: Understanding the various types of a vehicle suspension system

Components of an air suspension system

air_suspension_diagram

Air filter, air accumulator, relief valve, air spring, lift control valve, return valve, and supply line is the major component of an air suspension system. Below are the common parts of the modern air suspension system.

  1. each wheel has a vulcanized rubber air spring
  2. An air compressor is usually found in the trunk (boot) or under the hood of a car.
  3. A compressed air storage tank, capable of storing air at 150 psi (1000 kPa), may be provided for quick “kneeling.” (1 psi=6.89 kPa)
  4. a valve block with a sequence of solenoids, valves, and many o-rings that routes air from the storage tank to the four air springs
  5. an ECAS computer that communicates with the BeCM, the car’s main computer, and selects where air pressure should be routed
  6. a system of 6 mm air pipes that distribute air throughout the entire system (mainly from the storage tank to the air springs via the valve block)
  7. a desiccant-filled air drier canister
  8. Height sensors on all four corners of the vehicle, ideally based on resistive contact sensing, to provide an absolute height reference for each corner.
  9. Dunlop Systems and Components Ltd have proceeded to improve the products to the point where the Electronic Control Unit (ECU) can now be installed beneath the vehicle’s floor. The control valves are far smaller and lighter, and they manufacture their own compressors.

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Diagram of an air suspension system:

Diagram of an air suspension system

Construction

The figure above depicts the layout of an air suspension system. The four air springs, which might be bellows or piston-type, are positioned in the same location as the coil springs. An air compressor, air accumulator, relief valve, lift control valve, leveling valve, and pipeline are also included.

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Types of an air suspension system

Below are the various types of air suspension systems.

Bellow air suspension (Spring)

Rubber bellows make up this sort of spring. For proper working, the bellows are constructed into circular parts with two convolutions. As a result, the coil spring is replaced by a bellows-type air suspension.

Piston air suspension (Spring)

In these types of air suspension systems, a metal-air container in the shape of an inverted drum is used in this spring. The frame is attached to the drum. The lower wishbone is coupled to a sliding piston. A flexible diaphragm is used to create a seal. At its outer circumference, the diaphragm is closely attached to the drum’s lip, and at its center, to the piston.

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Elongated below air spring:

Elongated bellows are used when this suspension system is applied to the vehicle’s rear axle. These bellows are roughly rectangular in design, but they have semi-circular ends with two convolutions in general. These elbows are located between the vehicle’s rear axle and the frame. Radius rods are utilized at the rear axle to resist torques and thrusts.

Working principle

The working of an air suspension system is less complex and can be easily understood. An air suspension system is made up of an air spring, also known as plastic/airbags, rubber, and an airline system, all of which are coupled to an air compressor, valves, solenoids, and electronic controllers. The onboard compressor is an electric pump that uses various lines to supply air to the airbags. Valves are crucial in this situation because they control airflow and allow air to access various portions of the system. When the system adjusts for different driving circumstances, the solenoids open and close, inflating and venting the airbags, changing the amount of air entering each one.

The on/off switches are controlled by the electronic control module, which also monitors the pressure and adjusts the ride height. They are pliable and have some flexibility to them. The stiffness of the material rises when it is compressed.

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By adding air when riding fully loaded and deflating the air when riding light, air springs can provide customizable suspension and load support. You can lower the height of your vehicle so that it sits very low on the road, yet it still rises high enough to handle irregularities and rough areas. Air springs are the only load support component that can be adjusted, allowing for different load and leveling capacities as well as increased ride comfort.

Watch the video below to learn more about the working of an air suspension system:

Advantages and disadvantages of an air suspension system

Advantages:

Below are the benefits of air suspension systems in their various applications:

  • Increased driving comfort as a result of reduced road-noise, harshness, and vibration, which reduces driver fatigue.
  • Reduced vibration during heavy-duty driving means less wear and tear on the suspension system.
  • When a truck with a short wheelbase is unloaded, air suspension lowers the vehicle’s bouncing over bad roads.
  • Because the air suspension is better matched to the road conditions, higher cornering speeds can be achieved.
  • Air suspensions have a wide range of spring rates and load capacities, allowing for instant customization. In just a few minutes, the adaptability can get the ride load and ride height you want.
  • Adapting to diverse situations: adjusting the spring rates in combination with performance customization gives your vehicle limitless performance potential, allowing for real-time tuning and a cushiony ride for improved comfort on a bumpy road.
  • Towing: Trucks and heavy vehicles can tow heavier cargo more easily with this technique. When pulling high weights, drivers can increase the stiffness to improve riding comfort.

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Disadvantages:

Despite the good advantages of an air suspension system, some limitations still occur. Below are the disadvantages of air suspension springs.

  • Leaking is a typical flaw in all air suspension systems. When the system can no longer contain air, it will go flat. Air suspension issues are very widespread due to clogged airlines.
  • Initial costs: This is a one-time expenditure associated with purchasing a car. Air suspension is only available as standard equipment on luxury cars, high-end cars, and select SUVs.
  • Maintenance will be more expensive than with normal coils and shocks.
  • Because of the complexity of wiring, connections, and hose installations, installing an air suspension will take longer. The installation itself necessitates the usage of a number of different tools. As a result, engaging a skilled mechanic to handle it is the best way to ensure vehicle safety and integrity.
  • If not properly maintained, air suspension can cost three times as much to fix as a leaf suspension system over the course of ten years.
  • Because the weight of the air suspension system is heavier than the weight of leaf suspension, fuel economy may be compromised.
  • The failure of air struts or bags might be caused by rust or moisture from the inside.
  • The air suspension tubing connecting the air struts or bags to the air system has failed.
  • Failure of an air fitting due to damage sustained during installation or occasional use

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Conclusion

An air suspension is a type of vehicle suspension that is operated by an air pump or compressor that is either electric or engine-driven. The air is pumped into a flexible bellow, which is commonly composed of textile-reinforced rubber. It is made of an air spring. That is all for this article, where the definition, applications, diagram, components, construction, types, working, advantages, and disadvantages of an air suspension system. The meaning, characteristics, and types of air springs are also discussed.

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