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Lasers To Replace Sparkplugs In Engines?
An anonymous reader writes "For more than 150 years, spark plugs have powered internal combustion engines. Automakers are now getting close to being able to replace this long-standing technology with laser igniters, which should enable cleaner, more efficient, and more economical vehicles. Price and size have been issues holding up such an advance, but a Japanese team is set to announce they've overcome those hurdles."
Seriously, just think of the potential hacking uses of a pencil sized high powered laser! Cutting and drilling through hardened steel. Remote ignition of fires or detonation of explosives. Actual blinding weapons in a flashlight case.
I'm afraid they'll be too cool to be let out in public.
John
It expands the distance from stoichiometric that you can go (on the lean side, at least) while still being able to get it to catch on fire correctly while having a good lifespan of your igniter.
So it's not that the laser "needs" leaner mixtures; it's saying they enable leaner mixtures than current (mass-market) spark plug technology. And for steady-state cruising, that could be a great way to cut down on NOx emissions. (Not sure if it will reduce fuel consumption.) Of course, I thought the catalytic converters were already digesting all the NOx, so, I'm not sure why this is super-awesome...
According to the article, one of the main reasons spark plugs get gummed up is the electrical sparks they are putting out. Electric arcs tend to corrode their endpoints. With a laser, this isn't a problem. Also, the lasers aren't going to try to ignite combustion right in front of them: It's more efficient to ignite it away from them, in the center of the cylinder. Spark plugs can't do that at all.
Plus, of course, any laser capable of igniting a fuel-air mixture reliably in a few nanoseconds can burn through a bit of soot on the way.
'Sensible' is a curse word.
Diesel engines don't have spark plugs.
According to the article, one of the main reasons spark plugs get gummed up is the electrical sparks they are putting out. Electric arcs tend to corrode their endpoints. With a laser, this isn't a problem. Also, the lasers aren't going to try to ignite combustion right in front of them: It's more efficient to ignite it away from them, in the center of the cylinder. Spark plugs can't do that at all.
Plus, of course, any laser capable of igniting a fuel-air mixture reliably in a few nanoseconds can burn through a bit of soot on the way.
If the air fuel mixture is correct, the plugs on a healthy engine won't get gummed at all. If it is too rich or burning oil, it won't matter where the plug or spark originates as the build up occurs everywhere in the combustion chamber (although the rings scrape the wall clean). One only has to pull the heads off an engine to look at the carbon buildup that is no where near the spark gap.
But the article talks about it being cheaper (okay, more economical). Sparkplugs cost around $3 to $6 each. It seems that a laser strong enough to get through the carbon build up is going to cost more than that. Since plugs now last well over 36,000 miles in new vehicles, it seems trying to improve on an inexpensive technology with a high tech solution is anything but economical.
Shark injectors, obviously.
Every mans' island needs an ocean; choose your ocean carefully.
The reason why this is so novel is not the power of the laser, but it's size, timing and durability. It'll be interesting to see if NASCAR allows it, as efficiency is a big part of winning that closely regulated league.
Ummm... The mass-market car manufacturers abandoned carburetors for fuel injection back in 1987, yet NASCAR is still just thinking about using fuel injection maybe in 2012.
I think you can safely forget about laser ignition systems in NASCAR for a good long time after they're available in regular production cars. While NASCAR cars have been refined over the decades, they are still not using very much technology that would have been unfamiliar to a regular car mechanic in the late 1970s.
Now, if you'd said Formula 1, then that would make sense.
Putting moderation advice in your
It may just about be possible for racing, but normal owners would not want to have to readjust the carburetor every time the barometric pressure or temperature changed. And then you have the little problem that a carb will always change the mixture slightly when cornering. It is just not possible to adjust automatically for lateral, rotational and acceleration forces on a pot of gasoline which is being used as the input to a metered jet. Anybody familiar with racing carbs knows that they are a complete pain to set up and keep adjusted.
Your second point is nonsense. You're just saying "The injector has to be the correct size for the application".
Third, this is a gross oversimplification. You do not want the fuel completely vaporised. That will cause explosion. Enough fuel has to be vaporised for the ignition to work, but otherwise it has to be atomised - i.e. present as very small droplets - which can then burn at a controlled rate, preventing uncontrollable pressure rise with the risk of gaskets blowing and bearings failing. This problem is common to carburetors and injectors alike. (Diesels do not need any vaporisation at all because they do not have spark ignition.)
Only your last paragraph is correct. Injectors can do a better job, not only of metering fuel, but also of timing it, stratifying the charge, and ensuring that the mixture around the plugs is ignitable. A carb is basically a crude analog solution to a complex fluidics problem. (Incidentally you contradict yourself - you correctly refer to "atomisation" in that para, whereas you refer to "vaporized" above.)
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