A Lazered spark in the Combustion chamber....?

I am fairly sure I did not dream it -- an idea of lazered beams coming together and creating a spark in the combustion chamber.

Somebody `mentioned it in passing´ and then another, `... that Ford were spending some money on developing the idea.´ I asked an old Ford buddy and he denied all knowledge...

There was a Bantam in Australia which I am sure was running on the Hot Bulb principle although the Bantam builder didn´t say anything of his engine being Hot Bulb ingnition he did say it was on ether and ran similar to model aeroplane engine -- flat-out -- or nothing like....

Any comments appreciated??

Cheers!

I remember a couple of years ago that one of the Japanese plug manufacturers was experimenting with a tiny laser system , the one limiting feature of a conventional system is that fuel can only be ignited in the immediate area of the electrodes , then the burn hopefully developes to consume all of the available mix . A laser could penetrate to full chamber depth and vastly speed up combustion , and ignite less than perfect stoichiometric gas , which would help enormously .
Where it is all at now i have no idea , but it will come , and be pricey !

Trevor

Thanks Trevor!

I was not dreamiong then! And I feel fairly sure there was an Aussy Bantam using Hot Bulb ign...
with the fuel similar the aeromodellers and automodellers use, Ethyl Alcohol (Ethanol??) -- I think....

Ah! but the mobile telephones -- Walkie-Talkies -- the cops had in the fiftiesies were pricie too!!

Cheers!

One or two of many problems with laser ignition.

To achieve ignition temperature requires high power density from the laser. Fortunately as you will not need a continuous beam you can use a pulsed laser. You would almost certainly need to focus the beam into a spot of very small volume to achieve a realistic power density. It’s no good having a ignition system that needs a mains cable to power up the laser.

The major drawback is in keeping the optical access into the combustion chamber clear. Soot and deposit build-up would result in rapid absorption losses. Keeping the optics clean is the curse of optical engine work. Even the high power lasers we use have no effect on the evaporation of fuel droplets yet alone set light to anything. So no magic bullet, for all their problems spark plugs work – sort of.

Colin

A quick trawl of the net.

NETL in the States and NINS in Japan amongst other have reported some work in this area. The American effort is aimed towards large gas engines where the fuel gas is doped with 20% hydrogen. It takes very little to set hydrogen off so I assume they are having some problems with power density. The Japanese have embedded a YAG laser into the plug body and produces two spots (the American one is a single spot). They don’t say but I guess they use a beam splitter.

Both teams report a pulse energy in the order of 10mJ (a conventional spark plug is ~30mJ) and use multiple pulses per combustion event. It would seem that the Japanese use up to 3000 (!) pulses per combustion event which at 10mJ a go looks like a shotgun approach.

Interestingly the unique selling point seems to be the ability (maybe) to ignite lean air fuel ratios. So back to basics, get good cylinder filling and homogenous air fuel ratio and the humble self-cleaning spark plug will do the job just fine.

Colin

Thanks Colin!
I confess to try trawling but -- obviously -- got the wrong things.

Seems work has been done, then. Hydrogen would keep the chamber cleaner I guess... I suppose the furtherance of development depends whether auto companies feel the need is sufficient to spend money ... I guess we would still have Contact Breaker Points if that hadn´t happened half a century ago.

In the background is the situation of the spark plug companies wanting the lazer ignition to fail.

There are a lot of hidden secrets in the Counter Industrial Espionage files....

Cheers!