Nissan Provides General Overview of HCCI Work
06 August 2008
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| Nissan uses VVEL’s control of valve timing and lift to control temperature by using internal EGR in its HCCI development. Click to enlarge. |
During its recent Advanced Technology briefings in Japan, Nissan provided a general overview of its development of HCCI (homogeneous charge compression ignition) combustion engines. Nissan says it intends to roll out HCCI with the goal of reducing engine CO2 emissions by 30% from the current level by 2015. The work is part of Nissan’s Green Program 2010.
An HCCI engine ignites a mixture of fuel and air by compressing it in the cylinder, producing a low-temperature, flameless release of energy throughout the entire combustion chamber. All of the fuel in the chamber is burned simultaneously. Using a lean pre-mixed air-fuel mixture and keeping flame temperatures low helps keeps NOx and particulate production low. The lean-burn HCCI engine is a very good candidate for future clean and economical passenger vehicle applications, and automakers project significant cuts in CO2 emissions resulting from their use.
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| Extending the range of HCCI combustion is one of the development challenges. Click to enlarge. |
However, HCCI combustion is difficult to control, and currently automakers have succeeded in operating in HCCI mode only in a limited range. Expanding that operating range is one of the key challenges. (In May, GM demonstrated gasoline HCCI at idle, a significant extension. Earlier post.)
Nissan highlighted three tools and mechanisms it is using in its pursuit of HCCI. First, is in-cylinder temperature measurement. To accurately measure the gas temperature inside the combustion chamber, Nissan and Stanford University jointly developed technology to measure the real-time gas temperature inside the engine.
To control the temperature of the gas in the chamber Nissan uses its VVEL system. VVEL allows free control of the valve timing and lift for both intake and exhaust valves and thus manages the gas temperature inside the combustion chamber by altering the amount of EGR according to driving conditions.
Nissan has also developed a HCCI combustion simulation system which creates a high-speed three-dimensional representation of the chemical reactions in the HCCI combustion process.
HCCI combustion is a complex process of chemical reactions involving thousands of reaction formulae. Existing HCCI simulation can take up to 2 months to simulate such combustion processes in detail, making practical application to engine development difficult.
Nissan’s newly developed technology enables approximately 20 times faster HCCI simulation, utilizing the company’s accumulation of combustion data and combustion modeling technology. This large reduction in computation time—shrinking 2 months to approximately three days—enables practical application to engine development, Nissan said.
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| Output from Nissan’s combustion simulation system. To the left is a frame from a 3D animation. To the right is a plot of calculated results versus actual figures. Click to enlarge. |
Resources
Tsuyoshi Matsuda, Tomonori Urushihara, Takeshi Nakamura, Hiroki Wada, Toshiya Kono (Nissan Motor Company , Ltd.) A Study of Gasoline-fueled HCCI Engine—Mode Changes from SI Combustion to HCCI Combustion (SAE 2008-01-0050)
Akihiko Kakuho, Morihiro Nagamine, Yukio Amenomori, Tomonori Urushihara, Teruyuki Itoh (Nissan Motor Co., Ltd) In-Cylinder Temperature Distribution Measurement and Its Application to HCCI Combustion (SAE 2006-01-1202)
This area of endeavour is important and it is refreshing to read about the current state of development.
Sounds like we can't expect much from Nissan in this area anytime soon.
Informative article well written.
Posted by: arnold | 06 August 2008 at 03:10 PM
This pretty much confirms the results of HCCI research that GM and Daimler-Chrysler were doing.
The effort is, of course, to expand the HCCI mid-range window. But please remember that for a EREV ICE extender like the Volt setup, a narrow range is quite fine. The engine recharges the battery while operating almost exclusivly in the HCCI range getting all the benefit of the increased efficiency.
Many have proposed the benefits of a diesel engine recharging the hybrid battery, but the cost for diesel pollution cleanup on top of the hybridization cost, just seems prohibitive.
With HCCI operating on gasoline, its clean as a gasoline car, but with the mileage of the diesel, too. Of course that's only when the ICE actually rus and consumes fuel. In the case of a Volt, that might be only once a month, or not at all.
The GM selection of its bigger Family 0 ICE as opposed to a smaller brethren, was done partially because the larger version had just been redesinged for central placement of a GDI injector, that would support HCCI in a year or two.
It great to see Progress being made at all the automakers. The Nissan hybrid system seems to be an ersatz knockoff of the GM-Chrysler-BMW Two Mode hybrid, though.
I must say that these advances emerging from the Nissan engineering labs, contrast with all the public talk by Ghosn of BEVs, and BEVs only, as a Nissan direction.
Posted by: stas peterson | 06 August 2008 at 05:14 PM
I just hope that somebody figures out that for maximum benefit, an Atkinson engine similar to the one used in the Toyota Prius is made to work on HCCI mode for a series hybrid similar to the Chevy Volt linked to a generator via a CVT similar to the one built by Nissan so that the engine is kept running on its sweet spot.
Posted by: Freddy | 06 August 2008 at 08:18 PM
Yes it is great to see progress being made, or maybe other auto makers just getting on the bandwagon. The Nissan hybrid system seems to be a cut and paste paper design.
I think the GM-Chrysler-BMW Two Mode hybrid is much more sophisticated though.
See; Nissan Previews Upcoming Hybrid and New All-Electric Vehicles, New Fuel Cell Stack
at
http://www.greencarcongress.com/2008/08/nissan-previews.html#more
A series ICE does not need a CVT to keep the engine running on its sweet spot, the generator does that. In fact the Prius uses motor-generators to make it’s transmission act like a CVT.
Posted by: | 06 August 2008 at 09:33 PM
Nice to see some progress being made on their green program at Nissan. Personally, I'm most intrigued by the upcoming all-electric they are working on to produce in 2 years. My guess is that it will be customized to work with the Project Better Place system. More power to them! I hope this works out.
Posted by: Schmeltz | 07 August 2008 at 05:38 AM
Would it be possible to downsize the ICE e-gen by running it (on-off) at the highest economical speed, to keep the batteries charged in a series PHEV?
Why lug around more weight than required.
Posted by: HarveyD | 09 August 2008 at 10:51 AM
INNAS NOAX developed a free piston diesel powered hydraulic pump and demonstrated it. The design can be operated in high-compression-charge-ignition mode for any fuel including hydrogen and natural-gas which require very high compression. The absense of crankshaft and crank bearings allows for the compression ratios to be as high as necessary.
Because of its long use, people forget that the combination of crankshaft and flywheel is a hybrid system that takes the energy from one power stroke and uses it for the following compression stroke, but the steam locomotive did not much rely upon flywheel action. The mechanical valves and injection or ignition systems are just examples of mechanical computers. The hydraulic system of the NOAX engine is just another energy storage system like the flywheel, and should not be considered less workable than a flywheel in modern times.
Parry People movers make very good use of their very simple flywheel system in a hydraulic hybrid trolley.
The heart of the NOAX is a very powerful computer compared to most mechanical valve and ignition mechanisms, but it is far cheaper now to build and maintain such flexible electronic systems. Electronically valved hydraulic pump-motors are the perfect companion to the NOAX for a hydraulic hybrid.
The NOAX HCCI could be devoted entirely to generating electricity instead of pressure fluid flow by operating a linear generator or a hydraulic turbine or both. This should not be considered any stranger than turning an ordinary generator with the crank-crankshaft-flywheel-generator hybrids built and used by the millions each year. Honda and others have disconnected the generator speed from the electrical output frequency with silicon inverters.
The efficient automobile is not desired by most of the buyers. Nor is a low cost automobile desired by most of the buyers. Most of the buyers spend as much as they can afford to buy something that appeals to them for unspoken reasons:
High speed is most desired even though the highest speeds are illegal on all roads.
High horse-power large engines are most desired eventhough operating such an engine at full rated horse-power is impossible and would require the use of much fuel.
High torque is most desired even though it can not be used because of the car in front of you at the stop light or you are too engrossed in your cell-phone or you don't want to waste the gas.
Large size vehicles are most desired, but the weight costs fuel to move around.
Rare vehicles are most desired, but in traffic jams at most times the most common car will get you there in almost the same time.
All of the above choices and many others are only possible because of the heavy use of fossil fuels in their manufacture and distribution.
Full electric cars must be outlawed in favor of Plug-In-Hybrids to stop any thoughts about limited range. Lead batteries can be used now at low enough costs for Plug-In-Hybrids. Expensive and complicated and mildly more dangerous lithium batteries are only needed for very rich peoples' car purchases. The simplest hybrid system can cut fuel use, but the most important place to employ hybrid technology is in large low efficiency vehicles according to Wright of Wrightspeed.
For low operating costs, low manufacturing costs, low fuel costs and low repair costs with low pollution, a plug in electric-hydraulic hybrid with a NOAX engine would be a workable economic solution if made in large quantities. ..HG..
Posted by: Henry Gibson | 11 August 2008 at 03:03 PM
I think Freddy has the right idea. HCCI could be used in the sweet spot in a series hybrid. No sense trying to widen the band when you can narrow the output.
Posted by: sjc | 24 August 2008 at 07:22 PM
There is a company in Portland, Oregon already doing the same thing, getting great results, and are close to going to production with the product. Check them out. http://www.vftllc.com/index.htm
Posted by: Willy | 17 October 2008 at 11:21 AM