CAR&D

Suspension Designs

Ground bond

This expression is not common in English, but is much more general than "suspension", and does include all the system beetween the spriung mass and the ground : the steering, drive, brake and tire components. This allows to speak about comfort, traction, stability, braking and handling for all the vehicules, including the ones without a dedicated suspension (a kart for instance).

Classification

The following table provides a possible classification of the various types of suspension used in wheeled-vehicles.

 archi_tree.png  kin_tree.png  elasticity_tree.png  coupling_tree.png  steering_tree.png

3D essential features

Whatever the suspension system, the 3D wheel trajectory relatively to the sprung mass can be projected on the three main frames, which provide the longitudinal and lateral properties :

cin 3D.jpg

Double Suspension

Under the least comfortable driving conditions, we observed that the effort from the ground to the body included a significant horizontal element. In response, we conceived a double suspension system for high-performance all-terrain vehicles (Paris Dakar, military vehicles) that organizes the superposition of vertical and horizontal compliance. This design became the basis for the DPE suspension design, a hybrid thermal/electric 6x6 military vehicles by Nexter. Despite heavier non-suspended masses, this vehicle performed better than comparable vehicles on extreme obstacles. In 2000, a simple version based on a pseudo Mc-Pherson system for passenger cars was designed.

Variable Anti-Rollbars

Anti-rollbars have a significant influence on a car’s behavior at the highest lateral acceleration. In 1980, we designed and patented a simple motorized system providing of continuous variation of antiroll stiffness, able to be controlled by the present dynamic situation (load, lateral acceleration,...).

Heave-Control Suspension

Independent suspension design usually reflects the following logic: wheel stiffness creates a certain level of heave stiffness and the anti-rollbar adds an additional roll stiffness to achieve the specified roll stiffness targets

For modern ground effect-race cars, controling the heave and pitch to optimize aerodynamics is critical. Our solution was a specific heave-damper. We proposed a SARTA-LMP prototype, a completely transversal 3-damper arrangement with a full-floating heave-damper between the right and left rockers.

High-speed all-terrain vehicles, like those used in the Paris-Dakar, constitute another example of the demand for heave-control. The mechanical energy capacity is never sufficient at the landing phase of a big jump and the suspension rebound is quite dangerous. Mounting a third heave-specific damper specific improves jumping capacity and greatly simplifies the ride height variation (crossover). This solution was adopted on the Renault Koleos (Geneva 2003) concept car.

koleos koleos_susp

Clio V6 Trophy

The Clio V6 Trophy is a mid-engine 280 hp sports car competitor in international monotype circuit races.

Renault Sport Technologies wanted to improve its performance and driving ease while maintaining several current aspects, including some that are sub-optimal. To meet these challenging goals, CD&D did the following:

  • Inventoried all possible solutions.
  • Concentrated all possible changes on a minimal number of pieces.
  • Tested a preliminary version (proof of concept).
  • Studied and launched a small-scale kit that upgrades cars (see assembly manual, below).
  • trophy_eclate.jpg trophy_train-arriere

    F1 Suspension

    Two suspensions F1 is architecture all modern racing cars.

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