Engine down-sizing and down-speeding : A new challenge for torsional vibration filtration English Free Members only

Even if hybrid and electrical power-trains are expanding themselves in the market, the Internal Combustion Engine (ICE) is still very present. In order to meet the fuel consumption and CO2 emission requirements, ambitious research programs are currently running at Valeo. These programs are mainly focused on down-sizing and down-speeding of the ICE.

Down-sizing consists of reducing the number of cylinders (Typically 4 to 3 or 6 to 4) and the engine displacement. As the torque request is increased or at least kept the same, specific cylinder pressure is becoming higher and higher. As a consequence, the torque fluctuations (main NVH source in a vehicle) are more and more severe.
For fuel consumption reasons, the max engine torque is available at a much lower speed. Therefore, lower excitation frequencies turn out to be more difficult to filter. For the transmission field, down-sizing and downspeeding have great consequences in terms of torque fluctuations, amplitude and frequency.
Usually systems based on rotating inertia and stiffness is at a difficult limit to overcome. Therefore, major technological breakthroughs are necessary to meet the new requirements.