June 26, 2014
TROY, MI – French supplier Valeo says it will deliver its first electric supercharger for a diesel vehicle to be sold in Europe in 2016 with a 48V electrical system, and a second application will be geared to boost fuel economy.
Asked whether the electric supercharger will appear in the U.S. afterward, Jean-François Tarabbia, Valeo’s group senior vice president-research and development, tells journalists he is convinced it will, “and we will probably produce it in NAFTA as well.”
Production of the electric supercharger initially will be centered in Europe, he says.
For decades, forced induction meant employing turbochargers, which use exhaust gas to spin a turbine that pumps more air into the engine, or superchargers, which perform a similar function but are mechanically driven by the crankshaft.
In either case, large quantities of compressed air will boost horsepower and an engine’s power-to-weight ratio.
Valeo’s electric supercharger is driven not by the crankshaft but instead by a switched-reluctance motor that spins the compressor wheel. The device functions independently of the air loop and can deliver additional boost lightning fast – within 300 milliseconds.
Diagram shows placement of electric supercharger and bypass valve when not necessary.
The supplier considers this an ideal solution that works like a turbocharger but without the nagging problem of “turbo lag,” that hesitation when the driver steps on the accelerator and then must wait while exhaust gases spool up the compressor.
“When you downsize an engine or downspeed a powertrain, you will run into problems with low-end torque,” says Mark Glasson, Valeo’s North American business development director-hybrid and electric systems, during a recent technology expo at the supplier’s North American headquarters here.
“This answers the low-end torque question,” Glasson says. “The turbocharger does not.”
In truth, many modern engines, particularly those using twin-scroll turbochargers, have reduced the severity of turbo lag.
Depending on driving styles, supercharged and turbocharged engines can sap fuel efficiency. But when the new electric supercharger is paired with a regenerative braking system, Tarabbia says the system can boost fuel economy 20%.
Valeo considers the device a cost-competitive hybrid solution that can be quickly integrated with new-vehicle programs with minimal change to the powertrain.
When used with a conventional 12V architecture, the electric supercharger can reduce fuel consumption 10%, the supplier says.
Higher Voltage Shortens Response Time
The higher the voltage, the quicker the electric supercharger’s response time, Glasson says, adding that North American OEM customers are evaluating the device.
In terms of packaging, the electric supercharger can be located anywhere in the engine bay. But the closer it is placed to the engine’s intake manifold, the quicker the response.
On the cost side, Valeo says the electric supercharger is slightly more expensive than a conventional turbocharger.
The device is lighter than a standard Roots supercharger but slightly heavier than a traditional turbocharger because of the added electric motor, says Ron Wegener, application engineering manager for Valeo North America.
Many diesel engines in Europe currently need two turbochargers – a large unit to boost high-end torque and a small one for the low end. “We replace the smaller one with the electric supercharger, for the low-end torque,” Tarabbia says. “In some cases, we can replace both turbos.”
The concept faces a serious test this Sunday when Honda will use the electric supercharger on an NSX racecar in Colorado Springs for the Pikes Peak International Hill Climb.
Honda requested the device to see how it would perform in a challenging motorsports environment at high altitude, where conventional turbocharged engines can have trouble breathing.
Audi also has applied the electric supercharger in an A6 twin-turbo diesel prototype, apparently with impressive results.
Valeo entered the electric supercharger business by way of its 2011 acquisition of U.K.-based Controlled Power Technologies, which purchased the technology from Visteon in 2008. At the time, the supplier referred to the technology as Visteon Torque Enhancement System.
In 2009, CPT said it would begin producing the electric supercharger for a customer in 2010 and would reach full output in 2012.
Today, there are competitors with similar products, but Valeo considers its use of switched-reluctance motors a significant advantage that results in quicker response.
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