Air Suspension

Description

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An Air Suspension uses suspension dampers equipped with external inflatable air springs (Air Suspension Modules) or standalone air springs to control the height of the corners of the vehicle. The dampers may be either passive or controlled, and may be either struts or shock absorbers. A motor-driven air compressor provides high-pressure air to inflate the air springs, which act to elevate the height of that particular corner. When the air is let out in a controlled deflation, the vehicle returns to the desired trim height. Sensors are used to measure and compare the actual height of the vehicle to the desired height. The sensors send signals to an Electronic Control Unit (ECU), which automatically controls the activity of the air compressor and the inflation/deflation of the air springs.

The ECU and associated software may be standalone, or they may be incorporated into an Integrated Air Management Module (IAMM) along with the air compressor relay, valve block, thermal sensor, air pressure sensor, and display interface. This offers an improvement in vehicle packaging and system reliability.

Further modularization may be achieved in the Air Supply Unit (ASU). This unit incorporates the air compressor, Integrated Air Management Module, and air dryer.

An optional air accumulator vessel may also be utilized.

Technology

BWI Group has several decades of production Air Suspension experience, usually adapting and integrating basic technologies which have been used for multiple purposes: “air lift” struts and shock absorbers, air compressors, height sensors and ECUs. What is innovative is the way in which an Air Suspension can be used to accomplish multiple objectives.

Air Spring Modules (which can include either MagneRide dampers or passive twintube/monotube dampers) are validated in extreme conditions and for high pressure/high side load applications

The Integrated Air Management Module (IAMM) is an assembly that unifies the Air Suspension Electronic Control Unit and its associated software along with the air compressor relay, valve block, thermal sensor, air pressure sensor and display interface. This offers an improvement in vehicle packaging and system reliability.

Benefits

Air Suspensions can be used to accomplish multiple objectives. Historically, the original purpose was to compensate for the significant mass conditions under which a passenger vehicle must operate. Varying numbers of passengers and varying loads of luggage and other carried objects can change the sprung mass of the vehicle significantly. If there is only a driver, a conventional vehicle trim height (i.e., without an Air Suspension) would tend to have the rear of the vehicle in a high position. If the vehicle is fully loaded with the maximum number of passengers and carried objects, the rear will be low compared to an ideal trim height. That adversely affects the vehicle’s ride and handling characteristics. An Air Suspension can adjust to the desired trim height regardless of the load. A second benefit is that headlamp aiming, which is subject to regulatory approval in many countries, is made much easier because an Air Suspension keeps the vehicle at the desired trim height. A third benefit is the improvement in fuel economy which Air Suspensions can facilitate. An Air Suspension can be used to automatically lower the front of a vehicle once it reaches a certain speed. When this capability is integrated with exterior vehicle design (e.g., air dams and design elements aimed at creating laminar underbody airflow) a noticeable improvement in fuel economy can be achieved. At lower speeds, the Air Suspension returns the front of the vehicle to a normal trim level.