What’s the Air suspension System?

Speaking about the air suspension system most people think too far too upset, because in our minds it is either to please the big boss of high-end luxury car, or is for those who deal with ultra-running speed humps or bad road, orIt is used to give the opportunity to run wild in a luxury SUV. But in fact the air suspension system can justifiably claim to be a "simple good cause," the guy, it involves something even better than your home golf turbocharged or DSG gearbox is much less, but is improving ride comfort is far less urgent to improve combustion efficiency and necessary.

Air suspension is the use of air suspension shock absorber, mainly to adjust the air volume and pressure of the air damper by air pump, the hardness and elastic modulus can change the air damper. By adjusting the amount of air pumped, you can adjust the air damper and the stroke length of the chassis can be raised or lowered.

Air suspension with respect to conventional steel suspension system, has many advantages. Such as high-speed driving, the suspension can be hard to improve vehicle stability; and low or bumpy roads, the suspension can be softened to improve comfort.

Why use air suspension?

Very simple, because the average by a coil spring and shock absorber tube consisting of a suspension system and can not adjust the firmness and height. After the length and elasticity of the coil spring calm, suspension of height with hard and soft characteristics of curing down body will not change; the calm after the damping cylinder, the response speed and shock-absorbing characteristics of the suspension is also not changed.

But the problem is with the state of the vehicle with the road is changing, ah, for example, who do not want to run bad road when the suspension is soft and comfortable, solid and stable when running the curve. Or again a little stingy, when the rear brake if the front suspension can timely hardened alleviate nod degree, accelerated time hanging harden reduce the rise, and that nice ah, the body is always well-organized. To achieve all of these, it would require the entire suspension system, or even each individual wheel suspension damping characteristics can be quickly changed.

On the other hand there is a lot of flexibility to change the vehicle body from the need to distance. Such as customary "stick to the ground," but fear "Road see injustice," the car who needs another example of some heavy-duty commercial vehicles manned cargo. Of course, we are most likely to imagine that those who need off-road vehicles run on both sides of the city suburbs and SUV. If you have seen our era film footage of the off-road users should remember that the inside of the Q7 and Touareg, the two of them are equipped with height adjustable air suspension system, which can be described in the project day to shine, this is for us to provide today's article rich material.

As stated above ordinary coil spring suspension system's physical properties can not be changed unless replacement parts, so the manufacturer can only be based vehicle positioning and sales area, to make a compromise set to "maintaining the status quo." So not convinced engineers thought the air with readily available hardware and software to be made or height adjustable suspension system.

Air suspension How does it work?

In fact there are many types of air suspension, both soft and hard only adjustable height can not be adjusted, but also the level of hardware and software can be adjusted, for example, in the early part of the application of air suspension system limo, then adjust the two air chambers to change the air flow between the hard and soft suspension, but not with height adjustment function. This paper places the prevailing level of hard and soft adjustable air suspension as an example.

Through the above chart shows, air suspension with our body structure is actually familiar form of a coil spring + shock absorber tube is almost exactly the same, but in the upper portion of the coil spring has a closed chamber, by changing the chamber volume (up and down direction), you can change the length of the spring, to adjust the body from the ground and to some extent changed the hard and soft characteristics; additional vent damper part by changing the size of the motor, thereby adjusting the damping force of the shock absorbers.

Since you want to change the volume of the gas chamber through inflated, it is bound to involve a set of gas pumps with high-pressure gas storage mechanism. The number and level of the body to maintain inflated amount, by corresponding sensors and electronic control unit to decide. Our Volkswagen Touareg for example, the electric pump mounted on the chassis front passenger seat is probably the following location, and the high-pressure gas tank is located next to the trunk spare tire.

When the body needs to be raised, the system issued a directive to make the compressed air pump starts and the gas tank inside the compressed air supply to the spring air chamber inside, if you need to reduce the body only needs to control the exhaust valve exhaust air can be. As for the actual height of the body by the side of each vehicle wheel height sensors to monitor and revise. In the end when it needs to be raised when the need to reduce it? One can select interface to control by the driver through the car's model, on the other hand the system will automatically be automatically adjusted according to vehicle speed, road shock and other reference data.

The driver can follow the road from inside five modes need to choose, body height, while the suspension hardness change accordingly change automatically. Of course, taking into account the vehicle's stability and security, air suspension system will automatically change the condition of the vehicle from the ground. For example, in general a paved road, the Audi Q7 permanent ground clearance of 180mm; but when the vehicle speed reaches 120 km / h and kept more than 30 seconds later, the suspension will automatically lower the body's ground clearance 15mm, so better high-speed stability; if the speed for 20 seconds to keep the 160 km / h, the body will be reduced by 15 mm, the ground clearance is adjusted to just only 150mm.

Go wild and occasions, off-road mode allows the body ground clearance increased to 205 mm, helping to keep the Audi Q7 100 km / h in the general security bumpy mountain road by speed; the high-order mode allows the vehicle ground clearance increased to 239 mm, rose to the highest Q7 approach angle of up to 24 °, departure angle reaches 25 °, the maximum wading depth of 535 mm.

The other hand, the Touareg's air suspension provides four kinds of body height and three damping modes, respectively, through the back of the vehicle height adjustment lever knob and roll damping mode switching from the main regulator. On the surface can be combined 3X4 = 12 modes, but in fact the ground clearance required damping mode to select a compromise, such as when SPORT mode the damping, the ground clearance is no way to go to the maximum, so driving those who still want to grasp the actual height of the body according to prompts dashboard.

What are the limitations of the current still?

The more complex the system architecture also means more factors caused the failure, so the air suspension system problems of probability and frequency than ordinary coil spring suspension system. First, adjust the ride height of the air as a "propulsion", damper seal fiasco, if there is leakage of air suspension, then the whole system will be in a "paralyzed" state; secondly, because of the low air density relationship, with air suspension damping characteristics to make real-time adjustment, the response speed of the system and not the common hydraulic active suspension system.

In addition, compressed air from the pump, if you frequently adjust the chassis height, but also may cause overheating pump system, will greatly shorten the life of the pump, test drive the day we have encountered since the pump can overheat protection and short-term adjustment car high. Although there are limitations can not be avoided, but after I consult the brand and our service shop that, as long as the normal use of the words air suspension failure rate is not higher than other car parts, now rarely encountered because the air suspension itself damaged parts The cause of the fault. (Source: Pacific Automotive cloud lit)

★ Interpretation fast and stable flying carpet secret air suspension

Childhood, we read many fairy tales, for the future also has a variety of fantasy, although different protagonists different adventures, but there always seems to have a flying carpet, carrying us speeding. Growing up, we know that a lot of dreams are only illusions, and carpet has become a reality, it is the car. It took us rolling down the road of life, and let our "dream of flying carpet" more comfortable and more stable Secrets - air suspension, we are saying today is the protagonist.

● Define air suspension

Suspension means simply, it is the general term for the connection between the body and the wheels, by the shock absorbers, the guide means and the elastic components, air suspension with air springs is broadly as the suspension of the elastic element.

● Historical air suspension

Air suspension is not only born in recent years. In the early 1930s, Harvey • Firestone (Harvery Samuel Firestone) in his friend Henry • Ford (HenryFord) and Thomas • • Alva Edison (ThomasAlvaEdison) technical support, developed the air column form the air spring suspension system.

So in 1934, Harvey • Firestone in his own company (Firestone Tire and Rubber Company) in the first real air springs for the automotive industry. In 1938, interest in GM's happened to the air spring suspension system is installed on the bus. They cooperate with the Firestone company, he conducted the first round of tests in 1944. And in 1953 began production of passenger cars equipped with air suspension, which is the beginning of commercial vehicles using air suspension.

Before we understand the air suspension structure Let us look at the difference between the air suspension and the suspension of the ordinary, the elastic element common suspension spring, between the body and acts as an elastic contact of the tire, and bear and transfer the vertical load , ease and curb the impact caused by uneven road and so on, in order to accelerate the shock absorber damping vibrations, limiting body and wheel vibrations.

The air suspension with air springs replace the ordinary spring as the elastic member, it is because of a compressible and expandable gas, so you can play in addition to the air spring between the body and the wheels make contact elasticity to withstand and transfer the vertical load, impact mitigation and suppression caused by uneven road, you can also take the initiative to adjust the body height, which do the groundwork for the next we have to mention electronic control suspension system.

○ air suspension structure

The air suspension system generally consists of air springs, shock absorbers, guiding structure, the air supply unit (such as air compressors, single valve, gas, cylinders, etc.), height control valve. Now many brands, especially pay attention to the comfort of luxury cars or attention by a lot of SUV models are equipped or can be equipped with air suspension, here let us recently in the limelight of the new Audi A6L, for example, be carded

Air springs are added to the compressed air in the flexible sealed container utilizing the compressibility of air to achieve a non-metallic resilient spring action. It has excellent elastic properties, thereby improving the vehicle running comfort. And no matter how much the vehicle load, can be selected by changing the air pressure. For example, by adding additional air chamber means to increase its internal volume, can reduce the stiffness.

Air suspension system to resolve

Meanwhile, according to the compressed air used in different containers, air springs and membrane capsules have two forms, bagged air spring is sandwiched cords rubber balloon and enclosed therein composed of compressed air. Airtight inner layer made of good rubber balloon and the outer layer is made of oil-resistant rubber. Enclosed between the Festival and the Festival steel waist ring, the intermediate portion does not have the radial expansion and to prevent friction between the two sections. The diaphragm air spring sealed balloon made of rubber diaphragm and metal parts composition, will produce radial expansion. In the production car we've seen are mostly membrane air spring, and more applications in the modified field is bagged air spring.

○ shock absorbers

Air suspension at the rear suspension, shock absorbers and air springs are separated from the body of the level of regulation by the air spring, and we often say "Flex" has been referred to the independent shock absorbers responsible, in After the suspension of the new Audi A6L, the shock absorber using ZF company's products, this CDC variable damping shock absorber built-proportional valve, which can continuously control the fluid flow in the shock absorber to achieve adjustment damping coefficients. Front suspension is also true, but considering the space problem, it will air springs and shock absorbers CDC variable damping is integrated.

○ guide means

Air suspension with ordinary suspension guiding mechanism is not much difference, the new Audi A6L below shows the optional air suspension and anatomy ordinary suspension structure, also you can clearly see the air spring instead of the original a coil spring to become an elastic element.

Air suspension system to resolve

○ air supply unit

Air suspension system to resolve

The air supply unit consists of an air pump, air dryer, gas tank and other components, air supply assembly is generally placed in the engine compartment or trunk.

○ height control valve

Height control valve is an important part of the air spring suspension system, its role is to make an air spring under load are to maintain a certain height. Advantage of air spring, and only in the case of using a height control valve can be fully reflected. When the vehicle load increases, the body is equipped with height control valve will be down, connecting axle and height control valve pendulum rotation drive cam shaft is rotated so that the piston and the mandrel move the exhaust valve is closed, into the valve opens, at this time, coming from the intake port of the compressed air into the airbag. With the rise in pressure inside the balloon, the air spring height increases, the body will also rise, because the intake valve is closed to move the pendulum, then height control valve in a state of equilibrium. When the vehicle load is reduced, due to excess pressure inside the balloon, the air spring increases, and thus the body is also increased, and therefore, rotation of the pendulum, driven by the camshaft is rotated, so that the piston and ram down, so that the exhaust valve opens, the intake valve is closed, the balloon of excess pressure to the atmosphere. The body back to normal levels, then, the jack and on the move, the exhaust valve is closed, the height of the valve and in a state of equilibrium.

● Electronic Control Suspension System

With the continuous development of science and technology, electronic control suspension system enters into our lives. Early air suspension merely mechanical body height will remain within the set range, now equipped with an electronically controlled rear suspension car when load, speed, road conditions and other driving conditions change, the active suspension system can automatically adjust the suspension stiffness (vehicle adjustment and single wheel adjustment), but also by adjusting the air spring, to adjust the height of the purpose of the body, which can meet the cars ride and handling all aspects of stability requirements. So that the electronic control suspension system can be described as standing on the air suspension of the "shoulders of giants" on.

○ Dynamic Chassis Control Unit

Air suspension system to resolve

The new Audi A6L is equipped with a dynamic chassis control system, dynamic chassis control system and vehicle stability system (ESP) via a data bus to complete the transmission of information, based on travel demand, the dynamic chassis control system can pump, dispensing valve and CDC variable damping The proportional valve is controlled.

For example, we have chosen while driving dynamic mode, then the control system will receive instruction on the implementation of the above mentioned elements are controlled, CDC in the proportional valve can be adjusted to a minimum to reduce the flow of damping fluid velocity to achieve tight stretch of driving experience, the air spring pressure air will be reduced accordingly so highly compressed, so that the lower body; if we want to create a comfortable driving state, pump will provide more high-pressure air to tank, at the same time, the control unit which will tell the dispensing valve to give air pressure air spring delivery. Meanwhile the air suspension control unit via FlexRay in-vehicle networking standards and automotive networking, enabling cross-system and other important body acceleration signal, eliminating the need of early automobile systems require specific acceleration sensors.

Air suspension system to resolve

○ Here it is necessary to mention the body during the process of raising or lowering the details of the transition from the highest level to the lowest position, the system will this process is divided into three parts, the front will be dropping the first third of the stroke, is completed, the rear third of the stroke decreases, thereby further action will be completed twice from the highest to the lowest shift in the whole process, chassis control unit and the dispensing valve has been working in collaboration.

Air suspension system to resolve

Air suspension system to resolve

○ As the driver after you, via the MMI system in the comfort, auto, sports and choose from four modes defined in "automatic" mode, the new A6L to more than 120 km / h speed with more than 30 seconds, suspended frame will automatically be reduced by 10 mm, and provides better driving stability (speed of less than 35 km / h back to the initial height), in the "active" mode, the suspension starting height is lowered by 10 millimeters. In contrast, "elevated" mode, this mode A6L space vehicle from being an extra 10 mm increased to over small obstacles, the vehicle speed over 100 km / h will automatically fall back to the original height. And A8L compared with height adjustment range of the system is relatively small, intuitive feel for the driver may not be so obvious, variable damping and stiffness characteristics of touches for comfort have significant control or assistance.

Air suspension system to resolve

Select Dynamic mode while power output is not only more active, steering wheel feedback intensity has increased significantly, significantly improved pointing accuracy. The air suspension can be adjusted to the hard state, became very nervous the whole car tight, give the driver a sense of control purely mechanized.

Back comfort when comfort mode, the air suspension good filter road vibration, while maintaining proper firmness. Driving experience is still the familiar calm style.

Full Summary:

In fact, the air suspension is not a mystery, Airmatic suspension system such as the Mercedes-Benz S-Class is equipped with the Porsche Cayenne S and the Turbo models can optional PDCC Porsche Dynamic Chassis Control system, etc., many models are equipped with the optional air suspension or possible shelf or electronically controlled suspension system. We bring our air suspension comfort while intoxicated driving experience, we should also see the system structure is more complex because the air suspension failure probability and frequency much higher than the coil spring suspension system, if the air shock absorbers leak occurs, then the whole system will be in a "paralyzed" state. And if you frequently adjust the chassis height, but also may cause overheating pump system, it will greatly shorten the life of the pump. The so-called things are no absolutes, for his is the best.