In recent years, more and more focus has been drawn to the use of active suspension systems in vehicles. The major benefits of using active suspension compared to passive system is the ability to control roll, pitch and damping of the vehicle, which improves both safety and comfort. By using systems with a high efficiency, it is also possible to recover energy from the movement of the vehicle.
This is done by using a Magnetic Lead Screw (MLS) originating from a patent filed in 1925. Later, a patent in 1999 describes a PM type MLS which is also used in CIPED, as this type has shown to maintain a high shear force while having a large air gap. The MLS technology was developed and tested for wave energy, and it showed promising results regarding design and efficiency. Additionally, the work done in a preliminary study in CIPED shows the applicability of a MLS utilized in an active suspension system.
During the CIPED project, a paper regarding the design and test of the magnetic lead screw has been published, and can be seen by clicking the link below:
The working principle of the Magnetic Lead Screw (MLS) is similar to that of the mechanical lead screw. However, as the thread of the screw is made with magnets, the interaction between translator and rotor happens through the magnetic flux coupling between the rotor and translator. This makes it possible to construct a linear actuator with low friction and high shear force.
In CIPED, a novel Motor Integrated MLS (MIMLS) is developed and built, and can be seen in Figure 2. The MIMLS integrates both the motor/generator of the damper system and the spring needed to suspend the vehicle. The mechanical spring, however, is substituted with an air spring which adds additional controllability of the suspension system.