Laser Ignition May Replace the Spark Plug

dusty writes "Laser Focus World has a story on researchers from Ford, GSI, and The University of Liverpool and their success in using near-infrared lasers instead of spark plugs in automobile engines. The laser pulses are delivered to the combustion chamber one of two ways. One, the laser energy is transmitted through free space and into an optical plug. Two, the other more challenging method uses fiber optics. Attempts so far to put the second method into play have met some challenges. The researchers are confident that the fiber-optic laser cables' technical challenges (such as a 20% parasitic loss, and vibration issues) will soon be overcome. Both delivery schemes drastically reduce harmful emissions and increase performance over the use of spark plugs. So the spark plug could soon join the fax machine in the pantheon of antiquated technologies that will never completely disappear. The news release from The University of Liverpool has pictures of the freakin' internal combustion lasers."

Comments

So what happens

[Anonymous Coward]

When the vehicle gets to be a few years old, and the rings start letting extra oil past. Soon the lenses are covered with soot. Sparks can still jump through a moderate layer of soot, can the laser?

Re:So what happens

[fuzzyfuzzyfungus]

I'm not worried about the amount of energy getting to the cylinder, that can just be brute forced as you note. I'm more concerned about what the energy that doesn't make it will do. Fiber fuse could be fairly dramatic in such a system. Video of fiber fuse propagating.

I don't doubt that they'll work it out in the end, engineers have a long history of being clever like that; but it is going to take a giant pile of tweaks on top of the naive implementation.

Re:So what happens

[icebike]

Exactly.
What is the point?

Obscure claims of increased fuel efficiency and reduced emissions, based on what? A spark is a better combustion source than a laser.

This looks like a solution in search of a problem if you ask me.

Re:So what happens

[nmos]

Gasoline? Internal combustion engines? They are terribly wasteful of both fuel, and energy. Even a very efficient gas burning engine pumps fuel out the tail pipe, which is the reason catalytic converters are required on vehicles in the US. If a laser can set off a more thorough, more efficient ignition, that burns ALL of the gasoline in the cylinder, fuel mileage will increase, for certain.

Modern gasoline engines already burn something like 95%+ of the fuel that is pumped in so there really isn't that much room for improvement. I suppose any improvement is better than none at all but don't expect any miracles. FWIW this is one of the reasons those gasoline additives that claim to improve efficiency are mostly BS, even if they did cause the fuel to burn 100% it would be hard to even measure the difference in mpg.

Re:So what happens

[shiftless]

When it comes to ignition, compression is never a problem these days. What compression does do is increase *heat*. So unless your running gasoline with a higher octane rating, you will get detonation and pre-ignition the higher your compression ration is. ....and what happens when you use a laser to ignite a large portion of the fuel/air mixture at once, rather than using a spark plug to ignite a small flame kernel and waiting for it to propagate? The fuel mixture burns much more rapidly, allowing you to run less ignition advance. The result is more power, fewer emissions, and the engine is LESS prone to detonation. So then you can jack up the compression ratio and gain even more power.

In most likeliness

[east coast]

This will probably arrive as a viable and reliable technology right about the same time the internal combustion engine is on it's way out.

Don't think fax machine, think FD Trinitron.

Has other applications

[Anonymous Coward]

There's another obvious application for this - detonating nuclear bombs.

Nuclear weapons require that all the charges be detonated simultaneously, within nanoseconds, so that the implosion squeeze is precisely symmetrical. (OK, A-bomb geeks, I'm ignoring asymmetrical designs and flying-plate systems here.) If the timing is even a few nanoseconds off, the core won't be compressed; it will just blow out on one side, and a "fizzle" yield will result.

The usual trick for this is to use an "exploding wire" detonator. Unlike regular detonators, which have an intermediate explosive to start the main explosive, exploding wire detonators do it in one step, by discharging a capacitor bank through a resistance buried in the explosive. This takes a very fast high-voltage high-current switch, and the traditional solution is a krytron, a gas-discharge vacuum tube from the thyatron family. There have been big flaps over the years about various countries trying to acquire krytrons, which aren't classified but are export-controlled.

Krytrons are 1940s technology. This laser ignition system could be its replacement. One big laser pulse pumped through fibers of equal length to each detonation point should do the job. And it's off the shelf dual-use technology.

Lifetime?

[Anonymous Coward]

The problem with putting lasers in your engine is that it gets hot in there, and laser lifetime plunges drastically when you run them at elevated temperatures. I'm sure the dealers will love us having to replace our laser-plugs every two months, but no one else will.
(And if you're thinking thermo-electric cooling is the answer, that's going to use a whole lot of juice; don't know how feasible it is.)

Re:Great...

[Xenna]

That's why I'm putting an open source engine management system in mine:

http://en.wikipedia.org/wiki/MegaSquirt

Why not use microwaves?

[Zaiff Urgulbunger]

There's probably a good reason, but why not use microwaves? Wouldn't that be better to ensure even burn?