Lynne Kiesling
How cool is this? Purdue engineering researchers have made major progress on a new internal combustion engine design, using variable valve actuation. One remarkable innovation in this research is removing the connection between the crankshaft and the camshaft, which is what drives the pistons up and down. This design has been at the core of engines since the late 18th century, and finding a way to create work without that connection is a true breakthrough. It also means that the pistons can be tuned independently, and the ignition will be controlled with electronic sensors and software algorithms, which makes the engine more flexible in terms of fuel mix and can reduce engine wear and depreciation as well.
The concept, known as variable valve actuation, would enable significant improvements in conventional gasoline and diesel engines used in cars and trucks and for applications such as generators, he said. The technique also enables the introduction of an advanced method called homogeneous charge compression ignition, or HCCI, which would allow the United States to drastically reduce its dependence on foreign oil and the production of harmful exhaust emissions.
The homogeneous charge compression ignition technique would make it possible to improve the efficiency of gasoline engines by 15 percent to 20 percent, making them as efficient as diesel engines while nearly eliminating smog-generating nitrogen oxides, Shaver said.
This improved combustion efficiency also would reduce emission of two other harmful gases contained in exhaust: global-warming carbon dioxide and unburned hydrocarbons. The method allows for the more precise control of the fuel-air mixture and combustion inside each cylinder, eliminating “fuel rich” pockets seen in conventional diesel engines, resulting in little or no emission of pollutants called particulates, a common environmental drawback of diesels.
The variable valve actuation system makes it possible to “reinduct,” or reroute a portion of the exhaust back into the cylinders to improve combustion efficiency and reduce emissions. The system also makes it possible to alter the amount of compression in the cylinders of both conventional and HCCI engines and to adjust the mixing and combustion timing, allowing for more efficient combustion.
This is a good example of why focusing all of our research resources on technologies other than the internal combustion engine is ill-advised. Technology does make leaps, but it doesn’t usually make the dramatic platform leaps that would be the equivalent of the leap from internal combustion to hydrogen fuel cell. The hybrid engine and the variable valve actuation engine are two examples of incremental innovations on an existing technology platform that produce different outcomes from the standard engine platform, in terms of energy use and emissions, but are still essentially internal combustion engines. These innovations on the existing engine platform can enable us to meet our energy and emission objectives without having to wait for the next platform to evolve into a commercial product.
HT to Slashdot for the link.