GM Demonstrates Gasoline HCCI On the Road

Green Car Congress ^ | 08/24/2007 | Green Car Congress

[taildragger]

GM has demonstrated homogeneous charge compression ignition (HCCI) for the first time in two driveable concept vehicles, a 2007 Saturn Aura and Opel Vectra. The HCCI gasoline engines operate in mixed mode, using HCCI at lower loads, and reverting to spark-ignition at higher loads and speeds.

[taildragger]

When combined with the enabling advanced technologies such as direct injection, electric cam phasing, variable valve lift and cylinder pressure sensing, HCCI combustion provides up to a 15% fuel savings over conventional gasoline engines, while meeting current emissions standards.

I remember debating the limits of combustion capability when I was in college. HCCI was just a dream then. Today, using math-based predictive analysis and other tools, we are beginning to see how we can make this technology real. By combining HCCI with other advanced gasoline engine and control technologies we can deliver a good fuel savings value for consumers. —Tom Stephens, group vice president, GM Powertrain and Quality

In an integrated engine concept, HCCI, along with other enabling advanced technologies, approaches the engine efficiency benefit of a diesel, but without the need for expensive lean NOx after-treatment systems. Its efficiency comes from burning fuel at lower temperatures and reducing the heat energy lost during the combustion process. Consequently, less carbon dioxide is released because the vehicle’s operation in HCCI mode is more efficient.

The HCCI-powered concept vehicles—a production-based Saturn Aura and the Opel Vectra, both with a modified 2.2L Ecotec four-cylinder engine—drive like conventionally powered vehicles, but offer up to 15% improved fuel efficiency relative to a comparable port fuel-injected engine. The fuel efficiency improvement will vary depending on the vehicle application and the customer driving cycle.

The driveable concept vehicles represent some of the first tangible demonstrations of HCCI technology outside of the laboratory.

Highlights of HCCI technology include:

*

Diesel-like engine efficiency with substantially reduced after-treatment cost; *

Builds off proven gasoline direct-injection and variable valve actuation technologies; *

Adaptable to conventional gasoline engine architectures; *

Requires only conventional automotive exhaust after-treatment; *

Compatible with all commercially available gasoline and E85 ethanol fuels.

An HCCI engine ignites a mixture of fuel and air by compressing it in the cylinder. Unlike a spark ignition gas engine or diesel engine, HCCI produces a low-temperature, flameless release of energy throughout the entire combustion chamber. All of the fuel in the chamber is burned simultaneously. This produces power similar to today’s conventional gas engines, but uses less fuel to do it.

Heat is a necessary enabler for the HCCI process, so a traditional spark ignition is used when the engine is started cold to generate heat within the cylinders and quickly heat up the exhaust catalyst and enable HCCI operation. During HCCI mode, the mixture’s dilution is comparatively lean. The lean operation of HCCI helps the engine approach the efficiency of a diesel, but it requires only a conventional automotive exhaust after-treatment.

HCCI builds on the integration of other advanced engine technologies, some of which are already in production and can be adapted to existing gas engines. The cylinder compression ratio is similar to a conventional direct-injected gas engine and is compatible with all commercially available gasoline and E85 fuels.

GM demonstrated the adaptation of the HCCI technology in driveable concept vehicles based on conventional, production-based products like the Saturn Aura and Opel Vectra. The Aura features an automatic transmission; the Vectra, which is aimed at the European market, has a manual transmission.

Both vehicles are powered by a 2.2-liter Ecotec engine (180 horsepower [134 kW] and 170 lb.-ft [230 Nm] of torque) that features a central direct-injection system, with variable valve lift on both the intake and exhaust sides, dual electric camshaft phasers and individual cylinder pressure transducers to control the combustion as well as deliver a smooth transition between combustion modes.

A sophisticated controller, using cylinder pressure sensors and GM-developed control algorithms, manages the HCCI combustion process, as well as the transition between HCCI combustion and conventional spark-ignition combustion. The transition between the combustion processes is notable in the demonstration prototypes, but production versions are intended to deliver an imperceptible transition while driving, similar to the deactivation performance of GM’s Active Fuel Management system.

Currently, the GM demonstration prototypes can operate on HCCI up to approximately 55 mph, transitioning to spark ignition at higher vehicle speeds and during heavy engine load. An extended range for HCCI operation is intended as further refinements to the control system and engine hardware are made.

Perhaps the biggest challenge of HCCI is controlling the combustion process. With spark ignition, you can adjust the timing and intensity of the spark, but with HCCI’s flameless combustion, you need to change the mixture composition and temperature in a complex and timely manner to achieve comparable performance. —Prof. Dr. Uwe Grebe, executive director for GM Powertrain Advanced Engineering

GM’s global HCCI team will continue to refine the technology in the wide range of driving conditions experienced around the globe, from extreme heat and cold to the thin air effects of driving at high altitude.

In 2005, GM announced a three-year, $2.5-million research program with supplier Robert Bosch and Stanford University to accelerate development of HCCI.

[from occupied ga]

When listing it’s virtues they left out a 0 - 60 time of 47 seconds and a top speed of 82 MPH

[taildragger]

In my humble opinion, this makes Diesels look like boat anchors.

The Green Car World has already asked the million dollar question.

Will you GM add a HCCI engine to the Chevy Volt?

They have been aloof about the answer, but with the display engine being a 3 cylinder version of the Eco-Tech, you can see how that could be done.

[taildragger]

GA,

No, think of it as a form of controlled pinging. The market pressures are such they couldn't do that.

[taildragger]

BTTT

[SVTCobra03]

“When listing it’s virtues they left out a 0 - 60 time of 47 seconds and a top speed of 82 MPH”

No kidding. How about news about real cars like the Camaro? Will the top-of-the-line Camaro SS have the 500hp, supercharged LS3?

[Red Badger]

Rest In Peace, old friend, your work is finished....... If you want on or off the DIESEL ”KnOcK” LIST just FReepmail me........

This is a fairly HIGH VOLUME ping list on some days......

[Eddie01]

GM most certainly will if the HCCI can be design and production validated by summer 2010.

I doubt GM can considering HCCI is currently prototyped with low efficiency subsystems like temp/mix conversion.

General Motors is a great company pouring a majority of resources, their best and brightest into every aspect of fuel efficient vehicles to blitz the market with advanced hybrids.

Take note of the SUV hybrid variants available this fall with all Pickups following next year.

As for the Volt, the technology going into the cockpit is stunning. The fact that the show car styling is mandated, the human machine interface/features ground breaking and the interior styling uncompromised will make the Prius look like a VW “Thing” for the same money.

Mark my words.

General Motors is a great car company! Killing old stereotypes of the bygone dark days will take time, but they will die and soon.

Eddie01

[Abathar]

My parents were the proud owners of one of GM’s 864 engines, and then a diesel that was a converted gas engine after that. We kind of gave up buying a Chevy with any new engine design for at least 2 years, we learned our lesson the hard way.

[NRG1973]

I hate to be a spoilsport, but this engine is only 15% more efficient that our current IC engines. Thats not much when you consider that our gasoline demand grows about 1.5% per year. At that rate we lose the efficiency gains from this technology in 10 years.

The reality is that even with efficiency gains the country will need more energy as time goes on. Its time to open up those parts of the country (including offshore) that are currently “off limits” to drilling. It will take us 35-50 years to migrate from oil to another form of energy so we need to make sure we have access to oil for that long.

[from occupied ga]

I have Gm cars, they aren’t great, but compared to the Ford I once had they’re wonderful. :-) You don’t want to be on the leading edge of anything GM since they let their customers find their problems.

[taildragger]

I am not sure today’s marketplace and the dark clouds recalls have on public opinion, will allow someone such as GM to thrust cars on customers almost as if they were their prototype fleet.

[justrepublican]

What good is a 15% gain? It would only make up the 15% loss using e-85.

[Yo-Yo]

"Take Heart, old friend, you may have some life left..."

</Leg Pull>

[norwaypinesavage]

"think of it as a form of controlled pinging."

I think this analogy is accurate, and it also opens up discussion on additional issues with this engine. Direct ignition combustion produces higher forces and loads on an engine than spark ignition. Diesel engine designers compensate for this with much heavier engine components. Without this, a direct ignition combustion system is much noisier and has lower reliability that an spark ignition system. I suspect much more work on reliability and noise is in order.

[B Knotts]

I don’t see the point. It’s like a diesel, but less flexible, and requires a specific fuel with less energy density. Where’s the advantage?

[taildragger]

Less weight and cost of a Diesel to name two.

I now I am going to get grief from the latest generation Diesel folks, but non of the cold weather issues, and some of the Diesel high cost add-on band aids like Urea canisters etc. to meet emissions.

From what I read fuel economy in narrow bands increases as much as 40% and emissions can drop as much as 80%.

Also I have read it works better with poorer grade fuels, (less octane) which opens up all sorts of possibilities.

Google HCCI, interesting stuff....

I see it at the "Holy-Grail" for Piston Engines at this time.

BTW, there is a diesel version of this technology the acronym is PCCI (?).

[MSF BU]

The energy needs will be met and hopefully the US shortfall will be reversed through a variety of methods. Among the most important are the construction of nuclear facilities using the latest technology, probably standardized across the countries following in the wise footsteps of France. The French do this one right, and we should follow their lead.

[taildragger]

MSF,

Perhaps you can find an audio archive of James Woolsey when he was on Bill Bennett's show a while back

He is a hybrid/plug in advocate and was high on the Chevy Volt.

Nuke power for plug-ins usage for around town trips, especially as a second car-grocery getter type car, would hit the Saudi's right where we want to, the wallet. Not to mention as the former CIA director noted, much cheaper.

By the sound of his praise, I wonder if he took a trip to GM and had a briefing on their plug-in/Volt efforts.

[taildragger]

Oh, one more thing.

As Director Woolsey noted, They can run the Nukes at full power at night when you plug it in, when they are normally at low grid load, it then becomes a win-win!