Automotive

Laser igniters could spell the end for the humble spark plug

Laser igniters could spell the...
Spark plugs could soon be replaced be laser igniters
Spark plugs could soon be replaced be laser igniters
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Spark plugs could soon be replaced be laser igniters
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Spark plugs could soon be replaced be laser igniters

Internal combustion engines are likely to remain in widespread use for some time yet, but it's possible that we may be bidding adieu to that most iconic of engine parts, the spark plug. Researchers from Japan's National Institutes of Natural Sciences (NINS) are creating laser igniters that could one day replace spark plugs in automobile engines. Not only would these lasers allow for better performance and fuel economy, but cars using them would also create less harmful emissions.

Located at the top of each engine cylinder, spark plugs send a high-voltage electrical spark across a gap between their two metal electrodes. That spark ignites the compressed air-fuel mixture in the cylinder, causing a controlled mini-explosion that pushes the piston down.

One byproduct of the process are toxic nitrogen oxides (NOx), which pollute the air causing smog and acid rain. Engines would produce less NOx if they burnt more air and less fuel, but they would require the plugs to produce higher-energy sparks in order to do so. While this is technically possible, the voltages involved would burn out the electrodes quite quickly. Laser igniters on the other hand, could ignite leaner mixtures without self-destructing because they don't have electrodes.

The NINS scientists also address another limitation of spark plugs – the fact that they only ignite the area of the air-fuel mixture closest to them (the top), with much of the heat of the explosion being absorbed by the metal cylinder walls before it can reach down to the piston. Lasers, by contrast, could focus their beams into the middle of the column, from which point the explosion would expand more symmetrically – and reportedly up to three times faster than one triggered by a spark plug.

Additionally, engine timing could be improved, as lasers can pulse within nanoseconds, while spark plugs require milliseconds.

In order to cause the desired combustion, a laser would have to be able to focus light to approximately 100 gigawatts per square centimeter with short pulses of more than 10 millijoules each. Previously, that sort of performance could only be achieved by large, inefficient, relatively unstable lasers. The Japanese researchers, however, have created a small, robust and efficient laser that can do the job. They did so by heating ceramic powders, fusing them into optically-transparent solids, then embedding them with metal ions in order to tune their properties.

Made from two bonded yttrium-aluminum-gallium segments, the laser igniter is just 9 millimeters wide and 11 millimeters long. It has two beams, which can produce a faster, more uniform explosion than one by igniting the air-fuel column in two locations at once – the team is even looking at producing a laser with three beams. While it cannot cause combustion with just one pulse, it can do so using several 800-picosecond-long pulses.

So far, the laser-ignition system hasn't been installed in an actual automobile. The scientists are reportedly in negotiations with a large spark plug manufacturer and with global auto components manufacturer DENSO Corporation.

In the meantime, drivers wishing an upgrade from their "old school" spark plugs might be interested in Pulse Plugs, which reportedly boost engine efficiency and performance by storing ignition energy, then discharging it in the form of intense plasma balls.

The NINS research will be presented next month at the Conference on Lasers and Electro Optics, in Baltimore.

27 comments
mrhuckfin
Now this is something I\'ve been wondering about since the 70\'s! WAY cool idea and I hope it comes out soon. By the way the Pulse Star plugs really do work I\'ve been using them for a couple years now. :-)
schmoe90
I think you\'ll find that the fuel in a cylinder burns, as the engine\'s not strong enough to contain explosions - that\'s \"pinking\".
ccrider77
Schmoe - First of all, it\'s \"pinging\" - not \"pinking\". Pinging or pre-detonation is caused when the A/F mixture ignites prematurely, usually due to excess heat, poor fuel, incorrect timing or a lean condition. The fact is in a normal internal combustion engine, the air and fuel do in fact ignite and explode under pressure.
Check the definitions of burning, combustion and explosion. Explosions are rapid thermal chemical reactions which result in heat and an expansion of gases. That\'s what happens in your car engine. Burning is what happens when you sit around the campfire...
KellyRW
\"Pinking\" is a word used to mean the same thing as \"Pinging\", perhaps more often in the UK.

But I love this idea - weapons-grade lasers, available at your corner auto-parts store!
Loving It All
Quite the teaser article! How about giving us some actual comparison numbers - e.g., percentage improved horsepower, percentage improved mileage. That kind of thing.
Al Lukasek
If Formula 1 isn\'t doing it, don\'t expect it anytime soon for the general public. You\'re not going to be able to just throw them in a car. The entire system will have to be designed around them.
The Pulse plug is a capacitive discharge plug and not remotely related to a \"laser plug\"
Zappenfusen
It matters not how they accomplish it. Anything replacing our present antique Spark Plug which comes in priced competitely & improves fuel efficiency is long overdue. Today\'s high tech Pulse devices, one which costs the same as 6 normal plug changes, aren\'t affordable for the average home mechanic who also is fond of Food. Yeh, it\'s Pinging, you just got to love pollution controls.


Zappenfusen
Dave Mcclure
\'pinking\' is the correct term here in europe at least.
Zappenfusen
Please excuse, but it Pings under our Bonnets. We often forget the the www in the address. My first correction this week, made it all the way to Monday. No offense intended,
I love you guy\'s.

Zapp
Griffin
Dirty pinkos (old U.S. term,but not for pinging). once when I was very young I saw an injection/ignition system using lasers and exotic liquified gases(I forget the exact compound) but it burned exceptionally clean and it could reclaim the fuel several times.
There were a few articles on it in a performance boat magazine.
I always wondered why.
It was supposedly working but I always wondered if they got bought out,was it even real,etc.