Autoblog

Next-gen Volt could use diesel, two-cylinder or rotary range extender

Sam Abuelsamid — Wed, 26 May 2010 19:00:00 EST

Filed under: Hybrid, Technology, Hatchback, Chevrolet, Electric

2011 Chevrolet Volt - Click above for high-res image gallery

Back in 2006 when the Chevrolet Volt was first conceived, its extended-range electric (ER-EV) powertrain was originally dubbed E-Flex as its configuration was designed to be flexible. The only part of the system that was constant was the electric drive and the presence of a battery. The architecture was designed so any type of powerplant could be used as a range extender, and over the last three years concepts have been shown with flex-fuel three-cylinder turbos, inline-four diesels and hydrogen fuel cells.

Ultimately, powertrain chief engineer Larry Nitz and his team opted for a normally aspirated 1.4-liter inline-four for the first generation Volt because it offered the best combination of cost and efficiency. However, while working on the first generation Volt, work on the second-gen. model has been happening in parallel. Way back in May 2007 we talked to then-VP for R&D Larry Burns about using an HCCI engine for the Volt since it could be optimized to operate at steady state speeds and he agreed that was certainly one possible direction.

Right now the top priority for the second-generation Volt is driving down the cost of the powertrain, including the battery. Although automakers are always reluctant to talk about parts pricing, GM's project management VP, Jon Laukner, has hinted on more than one occasion that the Volt pack costs somewhere in the $600 per kilowatt-hour range or under $10,000 for the 16 kWh unit. The goal is to get that cost down below $400 per kWh in the next few years and a combination of increased volumes and LG Chem launching cell production in western Michigan will certainly help to achieve that.

Reducing the cost of the range extender will also play a part. GM's VP of global vehicle engineering, Karl Stracke told Inside Line that smaller range extenders in the 15-18 kilowatt range are part of the strategy and either a two-cylinder piston engine or a single rotor Wankel are possibilities to replace the current inline-four. Volt communications manager Rob Peterson confirmed to Autoblog that a number of different variants are being evaluated, but he wouldn't say if any particular direction has been selected yet.

Powertrain engineering consultant FEV has recently been showing off an ER-EV Fiat 500 with a Wankel range extender. While Wankels are not known for fuel efficiency (quite the opposite actually), a modern direct injected unit for this type of application could be highly optimized to provide acceptable performance and consumption. A Wankel also has the advantage of being both very compact for its output and vibration-free, making it well suited for this type of application. With the first generation Volt only expected to have about a three-year life-span, a final decision will likely be made very soon.

Gallery: Quick Spin: 2011 Chevrolet Volt

Photos Copyright (C)2009 Sam Abuelsamid / Weblogs, Inc.

[Source: Inside Line, General Motors]

Next-gen Volt could use diesel, two-cylinder or rotary range extender originally appeared on Autoblog on Wed, 26 May 2010 19:00:00 EST. Please see our terms for use of feeds.

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Lotus: Omnivore engine is 10% more efficient with more to come

Sam Abuelsamid — Thu, 10 Dec 2009 13:59:00 EST

Filed under: Technology, Lotus

Last March at the Geneva Motor Show, Lotus announced its new Omnivore research engine. The Omnivore is a two-stroke direct-injected engine designed to take advantage of the latest in electronic engine management and run on just about any liquid fuel (hence the name). In the time since the initial announcement, the boffins at Lotus Engineering have been exercising their creation on the dyno stand to evaluate its performance.

The single-cylinder engine uses an air-assisted direct injection system. A movable "puck" in the top of the cylinder head allows the compression ratio to be varied.

The engine has so far been run on gasoline in both spark ignition and homogeneous charge compression ignition (HCCI) modes. The HCCI mode is of particular interest because it is capable of providing diesel engine-like efficiency without the particulate and NOx emissions that require expensive after-treatment systems in a standard diesel engine. Lotus is claiming the Omnivore can operate in HCCI mode in a wide variety of operating conditions and even from a cold start, something that has been problematic for previous HCCI engines.

According to the initial test results, the Omnivore is achieving up to a 10 percent improvement in efficiency (as measured by Indicated Specific Fuel Consumption) compared to existing spark ignition direct-injected engines.

There is clearly a lot of work yet to do, but the concept behind Omnivore shows significant promise.

Gallery: Lotus Omnivore engine

[Source: Lotus]

Continue reading Lotus: Omnivore engine is 10% more efficient with more to come

Lotus: Omnivore engine is 10% more efficient with more to come originally appeared on Autoblog on Thu, 10 Dec 2009 13:59:00 EST. Please see our terms for use of feeds.

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We take a quick spin in GM's latest HCCI engine prototype

Sam Abuelsamid — Tue, 26 May 2009 14:00:00 EST

Filed under: Hybrid, Green, Technology, GM, Saturn

Since our first encounter with General Motors' HCCI (homogeneous charge compression ignition) engines in August 2007, the powertrain research engineers at GM's Tech Center in Warren, MI have continued plugging away at the technology, trying to turn it into a marketable reality. The basic premise of compression ignition is simple. Based on the Ideal gas law (PV=nRT), if you decrease the volume of a particular quantity of air, the temperature rises to the point where fuel will spontaneously combust.

The hard part is controlling the pressure, temperature and air/fuel mixtures precisely enough to manage that combustion without causing excess noise and engine damage. When we first tried the HCCI prototypes a couple of years ago, the engines had a fairly narrow band of HCCI operation with the engine running in basic spark ignition mode the rest of the time. Thanks to a newly developed mixed-mode HCCI feature and external EGR, the engines can now run in HCCI from idle all the way to 60 mph.

We had a chance to drive a Saturn Aura with an HCCI engine based on the 2.2-liter EcoTec four-cylinder around the streets near the Tech Center. The engine ran smoothly and transitions between HCCI and spark ignition really couldn't be felt. The only indication of a transition was a slight ringing sound over the first couple of power cycles after transition.

The basic hardware for a production HCCI engine is in place now, with the only new piece of hardware being a combustion chamber pressure sensor. GM is continuing to work on the control software to make this a robust system and even adapting the homogeneous charge and pressure sensors to diesel engines to reduce NOx emissions. GM says that HCCI engines can achieve about a 15% improvement in fuel efficiency compared to a similar spark ignition engine - at a much lower cost than a hybrid. The automaker hopes to have HCCI engines in production in about five years.

[Source: Green Fuels Forecast]

Continue reading We take a quick spin in GM's latest HCCI engine prototype

We take a quick spin in GM's latest HCCI engine prototype originally appeared on Autoblog on Tue, 26 May 2009 14:00:00 EST. Please see our terms for use of feeds.

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MIT researchers say HCCI cleaner, more efficient engine

Chris Tutor — Sat, 04 Aug 2007 15:32:00 EST

Filed under: Green, Technology

We're not gonna try to explain all the physics involved in this new engine design. That's for all you Autoblog readers with engineering degrees to do in the comments. But, from what we understand, MIT researchers have taken a long hard look at an engine design called homogeneous charge compression ignition (HCCI) and say it could run cleaner and more efficiently than current popular engine designs.

Conventional gasoline engines work by pistons compressing a mixture of fuel and oxygen that is ignited by a spark. Diesel engines work by injecting fuel into hot, compressed air which then ignites. HCCI is a mixture of the two methods. Air and fuel are mixed, injected into cylinder, then ignited by pressure from the piston.

One MIT researcher says HCCI could get 25% better fuel economy over a gasoline engine, while running cleaner than most diesels.

The article from MIT's Technology Review says several automakers are currently researching HCCI engines. Volvo has been testing an engine that can switch between spark ignition and HCCI. AutoblogGreen just recently wrote that Mercedes is working on what they call DiesOtto, which is basically HCC, as welI.

[Source: MIT Technology Review]

MIT researchers say HCCI cleaner, more efficient engine originally appeared on Autoblog on Sat, 04 Aug 2007 15:32:00 EST. Please see our terms for use of feeds.

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