New powertrain enhancements from Valeo

  • 31-Mar-2008 05:43 EDT
e-valve.jpg
Valeo claims carbon-dioxide emissions reductions of between 15 and 20% with the addit­ion of its electromagnetic valvetrain.

“It is our role as a supplier to create the new car which does not pollute as much,” began Valeo Chairman and CEO Thierry Morin, speaking at the Frankfurt Motor Show in September. Morin illustrated the point with projected annual global automobile production figures for 2014—88 million compared with an expected 68 million in 2008, rising to 1.2 billion by 2030. The pressure by governments to reduce carbon dioxide emissions is therefore irresistible, he thinks.

However, by using a combination of technologies, Morin believes that Valeo can reduce carbon dioxide emissions from a 2.0-L 125-kW (168-hp) turbocharged engine by up to 40%. The drawback is that the cost of this technology would add between €1000 and €1500 to the powertrain cost by 2012. “But,” added Morin, “OEMs have no choice.”

To achieve Valeo’s claimed 40% reduction in carbon dioxide emissions, the company calls on a range of powertrain technical solutions, some already available, others under development. The largest single reduction is derived from replacing the conventional cam-driven valvetrain with an electromagnetically actuated valvetrain (e-valve). The system, which won the Gold Award in the “Engineering and Advanced Technology” category at October’s Equip Auto Show in Paris, requires a 42-V power supply produced by a voltage inverter from the vehicle’s 12-V system.

The e-valve system can provide cylinder deactivation and infinitely variable valve timing, which can deliver up to 15% more torque at low engine speeds. Each valve is controlled by two magnets and a pair of opposing springs. The magnets, which are placed above and below an armature plate attached to the valve stem, catch the armature plate as the plate moves toward the magnet. When the valve opens, the upper magnet releases the armature. The valve opens as the upper spring uncoils and the lower magnet catches the armature plate, compressing the lower spring in the process.

Valve opening is controlled by the valve control unit (VCU), according to operating requirements. The VCU is cooled by the engine cooling system. Closure is a reverse of the opening process. Valves remain closed when the engine is not running. Valve opening and closing can take place more quickly than with a cam drive, which helps to reduce pumping losses, while a throttle air valve is not needed.

The system can be applied to gasoline and diesel engines, with or without turbocharging and with direct or indirect fuel injection. Valeo claims efficiency gains and subsequent carbon-dioxide emissions reductions of 15 to 20%. A vehicle equipped with this e-valve technology is scheduled to reach the market in 2012.

Valeo’s StARS starter-alternator, as fitted to the Citroën C2 and C3 and due to be used on the Smart Fortwo microhybrid drive, can deliver efficiency improvements of between 6 and 15%. According to Valeo, the familiar belt-drive system is currently capable of starting gasoline engines with displacements as high as 3.0 L, and even up to 4.5 L in the Valeo tests. The system can also start diesel engines with displacements of up to 2.0 L.

Smaller efficiency gains can be achieved by using a dry double-clutch system, which can provide smooth shifts for automated manual transmissions without increasing fuel consumption. Double-clutch systems such as the BorgWarner-based Volkswagen DSG rely on wet clutches with a consequent loss of efficiency compared to a manual gearbox. A dry double-clutch system should be capable of providing smooth automatic gear changes without the losses associated with a torque converter automatic. Valeo claims a 4 to 6% improvement in efficiency.

Similar reductions can be provided by an electrically operated coolant flow control valve and a cooled exhaust-gas recirculation system.

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