Getting to HCCI: superior performance for gasoline engines.General Motors is pursuing a number of approaches to providing more environmentally benign powertrain systems. One of them could stop all of the discussion of whether there will be an increased number of passenger cars in the U.S. powered by diesel engines because while the engine has energy efficiency analogous to that of a diesel engine, because it is a gasoline-powered engine, it doesn't require all of the expensive N[O.sub.x] aftertreatment gear that diesels have hung on them. It is called "HCCI HCCI Homogeneous Charge-Compression Ignition HCCI Haut Conseil de la Coopération Internationale (France) HCCI Harlem Congregations for Community Improvement, Inc. HCCI Human Capital Composite Index (VaLUENTiS) ," which stands for "Homogeneous Charge Compression Ignition." Essentially, this is ignition initiated by cylinder pressure rather than spark. Inside the HCCI engine--and GM has produced drivable versions based on the 2.2-liter, 180-hp Ecotec architecture and placed them in both a 2007 Saturn Aura The Saturn Aura is a mid-size car produced under the Saturn brand of American automaker General Motors. It debuted as a concept car at the North American International Auto Show in January 2005. and an Opel Vectra The Opel Vectra is a large family car produced by Opel, the main European subsidiary of General Motors. In the United Kingdom, it is sold as a Vauxhall. It has also been sold in Australasia as a Holden and in Latin America as a Chevrolet, although it has since been replaced in , so we're talking about conventional engine designs and conventional vehicles--gasoline is directly injected into the cylinder. Then through pressure, the gasoline is simultaneously burned. Because of this more-complete burning of the fuel, there are fewer emissions and improved fuel efficiency, sort of the best of all-possible worlds. However, the HCCI engine doesn't do away with spark plugs entirely because when there are cold starts, there needs to be something to provide the heat within the cylinders that's greater than that achieved through pressure alone. According to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. Uwe Grebe grebe (grēb), common name for swimming birds found on or near quiet waters in most parts of the world. Grebes resemble the loon and the duck; they have short wings, vestigial tails, and long, individually webbed toes on feet that are set far back , executive director for GM Powertrain GM Powertrain Europe is a company created by General Motors to develop engines and transmission for the GM group. It was known as Fiat-GM Powertrain until the termination of the GM and Fiat merger talks, and earlier as Opel Powertrain. Advanced Engineering, the trick of HCCI is that there needs to be careful adjustment of the fuel-air mixture in relation to temperature. He says that while there are but comparatively minor modifications to the engine design--this doesn't require a wholesale reconfiguration of a conventional engine by any means (e.g., there needs to be improvements in the water cooling Water cooling is a method of heat removal from components. As opposed to air cooling, water is used as the heat transmitter. Water cooling is commonly used for cooling internal combustion engines in automobiles and electrical generators. of the engine, which necessitates some modifications), which also means that existing manufacturing equipment and facilities are usable, thereby minimizing investment--the control technology and associated algorithms are the big challenges at present. Not only is it necessary to perform the aforementioned adjustments in real-time, but because the engine does use both HCCI and spark-ignition combustion depending on operating conditions, the controller must make the transition between the two imperceptible im·per·cep·ti·ble adj. 1. Impossible or difficult to perceive by the mind or senses: an imperceptible drop in temperature. 2. to the driver. [ILLUSTRATION OMITTED] So while GM is evidently well on its way to HCCI under the hoods of its vehicles, Grebe estimates that it may not be until about 2015 that those engines are there.--GSV |
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