HCCI engine closes gap between gasoline emissions, diesel efficiency

[nadepalma]

Source: http://www.autoweek.com/apps/pbcs.dl...1/TOC01ARCHIVE

Splitting the Difference: HCCI engine closes gap between gasoline emissions, diesel efficiency
By RICHARD TRUETT | AUTOMOTIVE NEWS
AutoWeek | Published 07/31/06, 2:54 pm et

It is a technology that melds a diesel engine's high efficiency and massive torque with a gasoline engine's low emissions and smooth running. And it could be the next big evolution of the internal combustion engine.

It's called HCCI, or homogeneous charge compression ignition. Major automakers in North America, Europe and Asia are spending millions to bring it to production.

General Motors expects to have a test vehicle with an HCCI engine running by next year. If it works as well as engineers expect, the next step will be to decide whether the technology is ready for prime time, says Uwe Grebe, GM Powertrain's executive director of advanced engineering.

Though HCCI uses proven technologies already in production, such as direct injection of fuel into the cylinders and variable valve timing, the combustion process is complex, and controlling it requires a massive increase in computer power.

Fuel economy quest

The rush to HCCI is being spurred by the quest to increase fuel economy without huge investments in new technologies. Engineers expect HCCI engines to deliver about 80 percent of the efficiency of a diesel engine at about 20 percent of the cost difference between a gasoline engine and a diesel.

To meet stringent emissions regulations around the world, today's diesels use expensive high-pressure common-rail fuel-injection systems and high-cost after-treatment devices in the exhaust system, such as diesel particulate traps. A gasoline HCCI engine could deliver almost the same fuel economy as a diesel for a lot less cost.

"The reason we think HCCI is such a great technology is that we get the fuel economy benefit, but we deal with emissions inside the combustion chamber," Grebe says.

The HCCI combustion process can work in both gasoline and diesel engines. But it doesn't turn a gasoline engine into a diesel or vice versa. In other words, a gasoline engine would still burn gasoline, and a diesel engine would still use diesel fuel. But the operations of both engines would move closer together because each engine would mimic the other part of the time.

That means a gasoline engine would ignite its fuel not with a spark plug but by compression of air and gasoline in the cylinder, just as in a diesel. In a diesel with HCCI, a glow plug might be used to ignite the diesel fuel, as a spark plug does in a gasoline engine.

Engineers have several hurdles to overcome before the HCCI engine will be produced.

The engine only runs in HCCI mode part of the time, such as when a vehicle is cruising down the highway at a set speed. Engineers have to find a way to smooth the transition into and out of HCCI mode. An engine running in HCCI mode produces more noise and vibrations.

Also, engineers are working to perfect the shape of the pistons and combustion chambers as well as the amount of fuel and the direction in which it is sprayed into the combustion chambers. The temperature of the air entering the cylinder also is important, because engineers have to determine how to make the fuel in the cylinder ignite evenly.

5 years away

How long will it take to perfect the technology? It depends on whom you ask.

Each automaker is at a different stage in its research, but the HCCI engine is at least five years away.

"We are working on the HCCI engine, but clearly it is a future technology," says Volkswagen AG spokesman Harthmuth Hoffman in Germany. "I believe we could see it on the road in five to 10 years."

Last month in Tokyo, Masatami Takimoto, Toyota Motor Corp.'s executive vice president of powertrain research and development, said HCCI is a long way off and might not be ready before fuel cell vehicles. "In Toyota's research center, the HCCI and fuel cell departments are in competition to be first," he said.

Ford Motor Co. engineers also are developing HCCI and say it could make production in as little as five years.

"We believe that the HCCI gasoline engine could deliver a substantial incremental efficiency benefit that could close the gap between gasoline and diesel engines," says Tom Kenney, a Ford research engineer working on HCCI in Dearborn, Mich.

Nissan is another automaker spending heavily to bring HCCI to production. Nissan has been working with researchers at Stanford University in California to understand the combustion process.

GM's Grebe believes GM is on the road to HCCI production engines. He sees the engine's control system, not its internal workings, as the biggest challenge.

Says Grebe: "I think the technical problems can be resolved. What needs to be looked at is the complexity of the entire system and the cost-benefit of the technology. The cost-benefit is highly dependent on what the cost of energy is. It is a technical problem where the solutions are coming together."

James Treece and Jens Meiners contributed to this report

HCCI facts

What it is: A combustion process in which a gasoline or diesel engine can run using either compression ignition or spark ignition
Benefits: Greater fuel economy and lower emissions of oxides of nitrogen
Who's doing it: General Motors, Ford, Toyota, Honda, Nissan, Volkswagen, BMW and others
Ready for production: 2011 at the earliest

[rwalth]

I have been follwing the progress of this technology for a couple of years now. I really hope they can be brought to market, one article I read suggested that they could be twice as efficient as todays best gasoline engines which would roughly translate into twice the fuel economy. This is the first article I have seen that suggested a timeline, if it could happen in 5 years, that would be sweet.

[Ultra Magnus]

I hope this is one area where GM can beat the others to market with a solid product. GM needs to be an innovator once again.

[jwrebholz]

This is the first I've heard of this technology. Sounds interesting, but it's a bit early to get excited about it. It's good to hear though that they're developing new technology to improve fuel efficiency.

[JVal14]

While I like to hear about any technology that reduces energy use, I can help but think that everytime there's a breakthrough with the internal combustion engine, it just further stalls efforts to break our dependency on oil.

But with this technolgy be relevent in five years? By then plug-in hybrids should be on the market. I suppose that some sort of balance would be reached. Some people will find plug-ins more practical, some will prefer the HCCI.

[Michael_S]

Originally Posted by JVal14

But with this technolgy be relevent in five years? By then plug-in hybrids should be on the market. I suppose that some sort of balance would be reached. Some people will find plug-ins more practical, some will prefer the HCCI.

Why not a HCCI hybrid? There's every reason to use both technologies. And it's possible the technology can be adapted to methanol, ethanol, butanol, or any other liquid fuel.

But when I read 'five years away', that makes me nervous. Controlled Fusion has been '10 years away' for over 30 years.

[01cavalier]

I wonder if there is a power and torque advantage?
Direct injection has already helped with power, hopefully most of GM's engines will have it soon. Sounds like HCCI would be a much better value than getting a diesel.

[mkaresh]

Originally Posted by rwalth

I have been follwing the progress of this technology for a couple of years now. I really hope they can be brought to market, one article I read suggested that they could be twice as efficient as todays best gasoline engines which would roughly translate into twice the fuel economy. This is the first article I have seen that suggested a timeline, if it could happen in 5 years, that would be sweet.

One of the magazines (C&D) said it gets 80% of the efficiency benefits of diesel at 20% of the extra cost. Which makes sense, because on the face of it this technology shouldn't be more efficient than diesel. So fuel economy won't be double. Sounds like a 25% to 30% bump, which is still significant.

[Havasavana]

I'd think Honda would be among the first to get this going. There was an WSJ article last year that they're getting close.

[rwalth]

Originally Posted by mkaresh

One of the magazines (C&D) said it gets 80% of the efficiency benefits of diesel at 20% of the extra cost. Which makes sense, because on the face of it this technology shouldn't be more efficient than diesel. So fuel economy won't be double. Sounds like a 25% to 30% bump, which is still significant.

The article that I referenced was in WSJ, and it was Toyota that said its goal for the technology was to double the efficiency and gas mileage of the gasoline engine. Obviously making it a goal does not mean it will ever become a reality. I know that there have been major problems with these engines at very low & very high rpm, it sounds now like they are looking at making a sort of hybrid that runs sometimes in HCCI mode and sometimes in conventional spark mode.

[rsbaker]

Sounds great but it had better be as bullet proof as a diesel motor and never break down and not need any supper expensive or complicated maintenance regimens and had better run on regular gas as well. If they can do all that and give me 40+ mpg it will be a hit.

[gmfan3]

Originally Posted by Havasavana

I'd think Honda would be among the first to get this going. There was an WSJ article last year that they're getting close.

Close doesn't cut it. They had a large hurdle left:

"According to the engineers cited in the Journal piece, Honda has been able to clear obstacles to create a prototype four-cylinder HCCI engine that runs smoothly in a low-to-medium speed range.
That, they said, should represent about 65% of the load range necessary to run a gasoline engine properly on the highway. The main challenge left to clear is high speeds, or above 4,000 revolutions per minute, the engineers said. A typical Honda gasoline-fueled engine covers a range reaching 6,000 RPMs."

[quinnp12]

Either way, it's still a race between this and alternative fuels. I mean honestly, I don't think the world is looking for a halfway point between the gas and hydrogen (or solar or whatever), it is looking for the saving grace at this point. The idea is nice, but it matters most if alternative fuels end up being twenty to thirty years off.

[rwalth]

Originally Posted by quinnp12

Either way, it's still a race between this and alternative fuels. I mean honestly, I don't think the world is looking for a halfway point between the gas and hydrogen (or solar or whatever), it is looking for the saving grace at this point. The idea is nice, but it matters most if alternative fuels end up being twenty to thirty years off.

I disagree, I think we need something to help curb our appetite for gasoline while alternative fuels are being developed. As pointed out earlier in this thread, if this technology were to be used in conjunction with other things such as E85 and hybrids it could make a big difference in the amount of petrolem we consume, and thus buying us more time to develop other alternatives.

[MrMax]

I wonder how this affects the engine itself. Would this process work in an OHV, or is it a technology that would have to be purely OHC in order for it to work properly? Or is it something else entirely? I'm not very familiar with it, does anyone know?