Fastlane: Pressure to Perform: The Internal Combustion Engine in a Sustainable Future

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By Paul Najt
Lab Group Manager, Powertrain Systems Research

While it is often fashionable for the media or government officials to proclaim the death of the internal combustion engine, there are those of us in the automotive industry, who would say that these proclamations are definitely premature!

At GM, we are working on sustainable, environmentally-friendly transportation solutions, and the internal combustion engine is going to continue to have a key role. In fact, through the introduction of exciting new technologies like direct injection, variable valve actuation and active control, we are continuing to improve the fuel economy and performance of the traditional internal combustion engine. And, we’ve been working hard to open the door to a radical change in the combustion process - known as homogeneous-charge compression-ignition, or HCCI for short. This new combustion process will enable a wide range of low fuel consumption and low emissions engines for our future transportation needs.

What makes HCCI unique is the ability to burn fuel in an engine at lower temperatures, reducing heat losses, fuel consumption and emissions. For the past 100 years, all industrial combustion processes from the engine in your car, to the burner in your furnace have relied on a flame that burned fuel at high temperatures, which generate high emissions and reduced efficiency. Now, we have the knowledge and technology needed to control combustion without a flame!

I first started working on HCCI as a GM-funded graduate student at the University of Wisconsin, exploring the possibility of implementing HCCI combustion in a traditional automotive engine. It was a bit of a joke among the other grad students - the idea of controlled combustion without a flame. However, to the amazement of many, we soon had a basic understanding of what was required to achieve HCCI combustion in an automotive engine. Over the past 20 years, technological advances in micro-computers, actuators and sensors have rapidly evolved our ability to potentially control the previously uncontrollable; we at GM have aggressively used our combustion and controls knowledge generated during that time to develop an advanced spark-ignition engine that incorporates HCCI combustion and — when combined with the enabling technologies I mentioned — provides up to a 15 percent improvement in fuel economy relative to the current production engine.

In the fall of 2007, the HCCI team was excited to demonstrate, for the first time to the media at our GM proving grounds, HCCI technology in a Saturn Aura equipped with an automatic transmission and an Opel Vectra equipped with a manual transmission. Less than a year later, in the spring of 2008, with our technology protected by more than 75 patents, we did something unique in the industry; we permitted journalists in Washington, New York and Los Angeles to drive a fully functional HCCI vehicle on the open roads - a vehicle capable of operating in HCCI mode from idle to 55 mph.

So what is next? Going forward, we are continuing to refine the technology to meet the challenges of robust performance over the life of the vehicle, from winter to summer, from sea level to high altitudes. We are working to integrate HCCI combustion into applications ranging from boosted spark-ignition engines, to diesels, to hybrids. We are also preparing for the day when we can routinely fuel our HCCI-based vehicles on cellulosic ethanol. By integrating advanced HCCI-based engines with advanced cellulosic ethanol, we can create sustainable, CO2 neutral solutions.

GM is taking the internal combustion engine to the next level with the development of HCCI combustion, and it’s really exhilarating for our team to be working on a technology that represents an important next step. You can click here to see a video from Popular Mechanics about some of the work we’re doing with HCCI combustion.

I welcome your comments and questions.

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