Car suspension system offers greater safety and efficiency

Scientists claim that a new electromagnetic suspension system could improve the comfort and safety of car journeys while reducing power consumption.

A team of Dutch researchers has developed a prototype suspension it says is smaller and more efficient than existing electromagnetic devices and can regenerate electricity for the battery.

The group, from the Eindhoven University of Technology, trialled the system on a BMW test car at the AutoRAI show in Amsterdam earlier this month.

The unit uses electromagnetic forces controlled by computer algorithms to react to bumps in the road more quickly than existing active-suspension systems that use hydraulics.

The researchers found that this increases ride quality by around 60 per cent, compared to the BMW’s existing passive suspension.

This also makes the car safer to drive because it is less likely to turn over during a sharp turn, said team member and PhD student Bart Gysen.

‘You can have many sensors in the car to sense the vibrations or whether the car is rolling and based upon that you can react in a very short time,’ he told The Engineer.

‘For example, if an accident happens in front of you and you do a very quick steering manoeuvre then it will quickly react.’

The system comprises a tubular actuator attached to the car and a permanent magnet array attached to the wheel, as well as a mechanical spring.

When an electrical current is supplied to the copper wiring in the actuator it creates a magnetic (Lorentz) force that moves the magnet array, allowing the wheel to move up and down quickly as the system reacts to bumps in the road or turns.

Additionally, the magnet induces a current in a set of aluminium rings inside the actuator, creating an electromagnetic damping effect that helps to absorb shock.

This part of the system, along with the spring, provides passive suspension that works even if the electrical power fails.

Four of these units would use an estimated 500W of power — one quarter of that used by hydraulic suspension. The induced electricity can also be captured and fed back into the battery.

Electromagnetic suspension has been developed before, notably by high-end stereo manufacturer Bose, but hasn’t been adopted by car manufacturers.

‘We tried to improve the idea to make the system smaller and more efficient, and included the passive damping,’ said Gysen.

‘The major difficulty was to provide the desired force within a small volume. We developed mathematical modelling to predict all the forces and use those to produce an optimal design.’

The Eindhoven project was funded by bearing manufacturer SKF and has so far been tested on a car’s front wheels. The next step will be to adapt the technology to all four wheels.