Electric Turbocharging

[kscarbel2]

Car makers are showing a growing interest in electric turbochargers as a way to help decrease the size of engines without sacrificing the power and responsiveness. Electric turbochargers offer added flexibility because they can produce more power at lower engine speeds.

Whereas exhaust-driven turbochargers require time to spool up, electric turbochargers boast the instantaneous response of an electric motor, eliminating “turbo lag” while ensuring high boost pressure at low engine speeds. Overall engine combustion efficiency is improved resulting in better fuel economy and lower emissions.

Equipped with a two-stage electric turbocharger, variable valve timing system, high pressure fuel injection and further optimized gas exchange cycles, Volkswagen’s four-cylinder EA2888 diesel engine ordinarily rated at 150 horsepower now reaches 268 horsepower. VW will begin producing the engine next year.

French parts maker Valeo will begin producing electric turbochargers from late 2015. The response time of their electric turbochargers, from idle to 70,000 rpm in less than 350 milliseconds, underlines the case for this new technology.

In December 2011, UK-based Controlled Power Technologies (CPT) sold its VTES (variable torque enhancement system) electric turbocharger series for light vehicles to France's Valeo.

One of the fuel economy benefits Valeo highlights is the combination of an electric turbo with the cylinder deactivation – i.e., the ability to shut off multiple cylinders under light loads in order to improve fuel efficiency. The fuel savings achieved by shutting off unneeded cylinders can be quickly lost when driving on roads that aren’t completely flat. Even a mild grade can cause an engine to switch back to running on all cylinders in order to produce enough torque to maintain speed. However with the addition of an electric turbocharger, the engine management system can request small amounts of boost on-demand to increase torque while climbing a grade while keeping as many as half of the cylinders inactive, yielding up to a 10% improvement in efficiency.

The advantages of an electric turbocharger also apply to commercial truck diesel engines.

The ability to gain immediate turbocharger response for low speed overtaking and hill climbs translates into reduced fuel costs and faster trip times.

A supplemental electric turbocharger would be particularly effective with urban buses and trucks operating in stop-and-go city conditions.

Take for example, an 11-liter engine equipped with a conventional turbocharger and a supplemental electric turbocharger. During low speed overtaking and hill climbs, the electric turbocharger would allow an 11-liter engine to temporarily provide the power output of a 13-liter engine, resulting in faster trip times and enhanced fuel economy.

The ability to mount an electric turbocharger in-line anywhere between the engine and the intercooler offers under-hood (under-cab in the case of COEs) packaging flexibility.

An electric turbocharger can also be utilized as a supplemental unit that comes into play at lower rpms, prior to when the primary exhaust-driven turbocharger ramps up.

Today, Controlled Power Technologies (CPT) is focused on commercial truck, bus and off-highway applications with its "Cobra" water-cooled electric turbocharger.

http://www.cpowert.com/assets/CPT%20COBRA_4pp_APR2014_4print%20%282%29-1.pdf

http://www.cpowert.com/Products/COBRA-Water-Cooled-Electric-Supercharger

Borg-Warner (Schwitzer) and Honeywell (Garrett AiResearch) are also developing electric turbochargers (no doubt Cummins' Holset unit is as well).

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[noload]

This is cutting edge.

[fullfuel01]

Some engineer are about to make big bucks with that stuff. If it work.

[mack mhe9]

I like it.

[Freightrain]

Interesting for sure. Likely more hi-tech then I've seen on Youtube?

[Phase 1]

[masterwelder]

First generation.

[kscarbel2]

Going Electric: The Next Phase in Forced Induction

Not long ago, the only info about electric supercharging in these pages was in the classified section next to a male-enhancement ad. Only one of those products actually worked.

Electric supercharging, long rumored but never fully realized, is finally happening. Audi’s upcoming SQ7 TDI pairs an electric supercharger with sequential turbos on the SUV’s 4.0-liter diesel V-8. It’s a first for a production vehicle.

As with a conventional centrifugal supercharger, an e-supercharger uses a traditional compressor wheel but drives it with an electric motor rather than a crank-driven belt. E-superchargers draw their power from batteries or capacitors, which can be charged via regenerative braking or, in the case of the SQ7, a beefy generator and a 48-volt sub-system.

The biggest benefits of e-supercharging are power and response, particularly at low engine speeds. Because an e-supercharger’s ability to create boost is not coupled to exhaust energy or engine rpm, it offers flexibility not found in alternatives. Though traditional turbocharging remains a more efficient means of adding power, it has drawbacks such as lag.

As engines downsize and pressurize, e-supercharging offers the ability to size a compressor for a power target without sacrificing low-rpm drivability. It does so by filling in the torque-less void below the turbo’s threshold for creating boost. This is exactly how Audi is using the Valeo-supplied electric supercharger in the SQ7 TDI.

Electric superchargers won’t replace turbos, but they allow for the optimization of turbos and other technologies. For example, deactivated cylinders can remain dormant longer when supported by e-supercharging. And in Miller-cycle engines, which have a longer-than-normal expansion ratio, an electric blower can replace a traditional supercharger to reduce parasitic losses. Valeo describes its e-supercharger as an enabling technology, which gives it at least one thing in common with those male-enhancement products.

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