A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed fuels such as aerosol, gasoline, ethanol, and liquefied petroleum gas by means of an electric spark.
Spark plugs work by sending small, high-voltage electrical sparks across a gap between two metal electrodes. The spark ignites the air-fuel mixture in the cylinder producing a controlled explosion that forces the piston down to the bottom of the cylinder, generating the horsepower needed to move the vehicle.
Engines make NOx as a byproduct of combustion. If engine runs leaner burn's more air and less fuel they would produce significantly smaller NOx emissions.
Spark plugs can ignite leaner fuel mixtures, but only by increasing spark energy. Unfortunately, these high voltages erode spark plug electrodes so fast, the solution is not economical.
At this year’s Conference on Lasers and Electro Optics (CLEO: 2011), held in Baltimore on May 1-6, researchers from Japan describe the first multibeam laser system small enough to screw into an engine’s cylinder head.
According to Taira, conventional spark plugs pose a barrier to improving fuel economy and reducing emissions of nitrogen oxides (NOx), a key component of smog.
Lasers also improve efficiency. Conventional spark plugs sit on top of the cylinder and only ignite the air-fuel mixture close to them.
Taira explains, they can focus their beams directly into the center of the mixture, expanding the Flame more symmetrically and up to three times faster than those produced by spark plugs.
Equally important, he says, lasers inject their energy within nanoseconds, compared with milliseconds for spark plugs. “Timing — quick combustion — is very important. The more precise the timing, the more efficient the combustion and the better the fuel economy.
A commercial automotive engine will require 60 Hz (or pulse trains per second), Taira says. He has already tested the new dual-beam laser at 100 Hz. The team is also at work on a three-beam laser that will enable even faster and more uniform combustion.
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