Innovative alternative suspension technologies



Peter Els
06/16/2014

In an ongoing endeavor to control ride height several teams have come up with a passive system which meets the FIA’s regulations: Namely the Front and Rear Inter-Connected (FRIC) system.

Although details are closely guarded it is believed the FRIC system, with the hydraulic actuator (lower arrow) housed in the sidepod, displaces hydraulic fluid (the upper red arrow shows the fluid reservoir) from one end of the car to the other in order to maintain a constant ride height and aerodynamic balance.


 photo FRIC_system_zps96ea8a44.jpg

Image credit: www.formula1.com

Ride height is not the only dynamic that influences the performance of modern race cars: The quest to dampen out vibrations and harmonics set up by the movement of the wheel and the spring’s reaction to this is also ongoing.
One such damper that has been particularly successful is the "inerter" invented by Malcolm Smith of Cambridge University.
Also known as the J-Damper (Its project code name) the inerter looks like a conventional shock absorber, with an attachment point at each end: One of which could be fitted to the car body while the other is attached to the wheel assembly. A helix plunger slides in and out of the main body of the inerter as the car moves up and down, forcing the rotation of a flywheel inside the "damper".
 photo J_damper_zps39cf730a.jpg

The spinning flywheel stores rotational energy, and in combination with the springs and dampers, controls the oscillation of the wheel. Although the technology holds obvious potential as a passive system, it doesn’t appear as if this has received much attention for use in road cars.

Unfettered by rules, OEMs have chosen to pursue more advanced solutions; such as the GenShock Active Suspension currently being developed through a partnership of Levant Power and ZF Friedrichshafen AG.
Rolf Heinz Rýger, head of the Suspension Technology business unit of ZF's Car Chassis Technology division proclaims: "The objective is to develop the world's first fully active and regenerative suspension, make it ready for volume production and introduce it to the market."
The unit which consists of an electric motor, control unit and an electrohydraulic gear pump is fitted to the outside of the ZF damper.
 photo ZF_damper_zps2b9f0591.jpg

Image credit www.digitaltrends.com

The gear pump, driven by an electronically controlled electric motor, controls the oil flow in the damper which in turn regulates the damping force required for the prevailing conditions. Furthermore, the shock absorber continuously harvests energy from the movement of the suspension which would normally be dissipated as heat and converts this into electrical energy.

Suspension system development is not only about improving ride and handling. With legislation forcing reductions in emissions and fuel consumption vehicles are becoming lighter, and although this has many benefits, the reduction in sprung mass means that to maintain acceptable levels of performance unsprung mass also needs to be trimmed.

Peter Els is a technical writer for Automotive IQ

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