Hydro-elastic Vibration Decoupling

The two main functions of a suspension are firstly to limit relative displacements of suspended masses, for example a powertrain with respect to the bodywork of a vehicle, and secondly to filter medium and high frequency vibrations to give a good degree of vibrational and acoustic comfort. Although the first function requires the highest possible stiffness in all directions, the second function can be better satisfied if the stiffness is as low as possible for the vibration amplitudes and frequencies to be filtered.

While elastomers only enable an adjustment between damping and resilience, other compromises are possible with hydraulic parts. They can add damping to one of the engine support axes, by means of a hydro-elastic device within a clearly identified frequency range. Damping is usually oriented along an almost vertical axis, to calm powertrain up-down movements.

Hydraulic parts usually use amplitude decoupling devices. This type of decoupling gives good filtering for the highest frequency excitations for which amplitudes are low.

Paulstra also makes controllable or two-mode alternatives that add the possibility of improving services for two defined operating cases. The adjustment of a suspension can be modified while running to optimize filtering as a function of the vehicle life situation. For example, priority could be given to filtering when stopped and when the engine is idling, and damping can be restored while running.