Novel electric supercharger aimed at truck and bus diesel downsizing 26 September 2014

Controlled Power Technologies (CPT) is showing its novel Cobra water-cooled electric superchargers at the 19th Supercharging Conference, being held in Dresden, Germany this week (25 September to 2 October 2014).

Nick Pascoe, chief executive of CPT, says they are aimed at providing affordable hybrid systems for heavy-duty commercial vehicles – effectively reducing NOx and CO2 emissions and challenging both engine size and after-treatment required to meet Euro 6.

"CPT's heavy duty compressors have been developed as original equipment for diesel engines in off-highway and commercial vehicle applications using 24V or 48V architecture in a low-cost hybrid system," states Pascoe.

"Cobra builds on the experience gained by commercialising our VTES electric supercharger for passenger cars [sold to Valeo in 2011]," he explains.

"We are now focusing on trucks and buses," he says, adding that the time is right for OEMs to "reconsider the design of the charging system" as powertrains see more electrification.

Unlike mechanical superchargers, electric compressors are decoupled from the engine, which means air is delivered almost instantaneously – spinning up to 70,000rpm in less than half the reaction time of an F1 driver and in a fraction of the response time of a turbocharger – with a mass flow rate of up to 800kg/h.

The result is more efficient combustion and torque delivered at low engine revs, so improving the dynamic response of a downsized turbocharged engine, as well as reducing its fuel consumption by up to 10%.

It's an efficient way of using 2—9kW of stored electrical power. And depending on the rate of fuel injection, the system can deliver an additional 15—70bhp (20—90kW) at the crankshaft for up to 30 seconds.

"An electric compressor facilitates radical downsizing with fewer cylinders and smaller engine displacement," says Pascoe.

"That's how we gain the extra fuel economy, but without compromising vehicle performance. It really does mean getting a quart out of a pint pot."

He points to powertrain specialist AVL's work with CPT on applying the new boosting technology, as validated in the 48V LC Super Hybrid programme for passenger cars, funded by the Advanced Lead-Acid Battery Consortium (ALABC).

"We are now applying CPT's switched reluctance motor-generator technology to electric supercharging of large diesel engines," states Andy Dickenson, senior manager in charge of CPT's Tigers and Cobra technology.

"Cobra [COntrolled Boosting for Rapid response Applications] can help reduce NOx and particulates as well as CO2 emissions, thereby moderating the need for expensive exhaust after treatment to meet Euro 6 requirements," he adds.

CPT insists that Cobra is particularly effective with urban buses and trucks, subject to continuous stop-start operations.

"Another major environmental advantage of our switched reluctance technology is the elimination of permanent magnets in our electrical machines, which replace the need for expensive rare earth metals by using integrated electronic switching." Comments Dirk Zepp, sales manager CPT.

Author
Brian Tinham

Related Companies
Federal-Mogul Controlled Power Ltd

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