October 3, 2005 It has been a sudden realisation - the world is running out of oil and the laws of supply and demand are set to make petrol prohibitively expensive in the very near future. Sonex Research has a new combustion technology that offers significantly better fuel consumption and greatly reduced emissions. The Sonex GDI Combustion System uses pistons modified to carry a chemical charge that initiates combustion from one cycle to the next, thus eliminating the need for spark plugs. High compression, typical of diesel engines, is no longer needed to make the fuel ignite; in fact, the chemistry causing this auto ignition process exists only at lower compression ratios. Thus, a low compression engine, typically used for burning gasoline, can be designed to burn either a lighter alcohol fuel like ethanol, or a heavier fuel like (bio)diesel when equipped with Sonex pistons, common rail direct injection system and associated electronic control system to control injection pressure and timing. The technology could well be first deployed powering UAVs for the military in Iraq. By James Bauernschmidt
Sonex Research Company of Maryland, USA, believes much better fuel efficiency will be achievable when the Sonex Controlled Auto Ignition (SCAI) system is fully developed for Gasoline Direct Injected (GDI) engines using no spark ignition or throttle. The Sonex GDI Combustion System could improve fuel mileage by at least 25%. Dr. Andrew Pouring, a former chairman of the Dept. of Aerospace Engineering at the US Naval Academy, in his research found that pistons can be modified to carry a chemical charge that initiates combustion from one cycle to the next, thus eliminating the need for spark plugs. High compression, typical of diesel engines, is no longer needed to make the fuel ignite; in fact, the chemistry causing this auto ignition process exists only at lower compression ratios.
Thus, a low compression engine, typically used for burning gasoline, can be designed to burn either a lighter alcohol fuel like ethanol, or a heavier fuel like (bio)diesel when equipped with Sonex pistons, common rail direct injection system and associated electronic control system to control injection pressure and timing.
The piston head is designed with micro-chambers (MC) containing small connecting holes to the main combustion bowl in the piston. The initial combustion is brought about by the use of glow plugs which are turned off after starting. When fuel is directly injected into the engine at a precise moment, the SCAI design allows a small portion of the fuel to enter the MC.
This allows a slow chemical reaction in the MC which continues into the next compression cycle, thus providing the “chemical spark” for the next combustion. In a low compression engine, a more complete combustion of the fuel occurs at a lower temperature. As a result, soot and toxic emissions get reduced by over 80%. The turbulence of high-speed airflows in the connecting passages and the MC chemical reactions prevent these chambers from ever becoming clogged. A heavier fuel with more energy in it can now run in a lightweight engine more efficiently and with cleaner exhaust. Consequently, Sonex brings about the best of both worlds.
The main customer of SCAI has been DARPA (Defense Advanced Research Projects Agency). Currently, under their DARPA contract, Sonex Research is continuing development of a multi-cylinder, high power output, lightweight piston engine to comply with a DoD policy directive that mandates heavy fuel for all engines; this engine has already demonstrated a 25% reduction in fuel consumption compared to its performance on gasoline.
Gasoline engines are typically 25% to 30% lighter than diesel engines. Gasoline engine designs with the SCAI technology that can burn kerosene-based heavy fuels (JP5/8) would address DoD performance, logistics, and safety requirements.
So why hasn’t the automotive industry snatched up this technology? It’s the “not invented here mentality” according to Dr. Pouring. “If the automaker hasn’t invented the technology in its own house, the automaker is highly reluctant to use it, moreover, the automaker requires full compliance with emissions regulations before even taking a look. This is a daunting task.”
However, circumstances might make this industry reconsider. Fuel efficiency improvement is addressed in the Energy Bill signed into law in August in the USA. Section 773 states: “..the National Highway Traffic Safety Administration (NHTSA) shall initiate a one-year study and report to Congress of the feasibility and effects of reducing by model year 2014, by a significant percentage, the amount of fuel consumed by automobiles.”
Sonex Research seeks to be at the forefront of this initiative by providing this NHTSA study with compelling data on how its technology could cost-effectively improve fuel mileage 25% to 30% while reducing exhaust emissions. Once the US Congress is made aware that much higher standards are achievable, these standards could become mandated as federal law. In the meantime, consumers can rightfully demand better engines, knowing the Sonex technology is available.
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