back to article Lasers set to replace spark plugs in car engines

Spark plugs in petrol engines are set to be replaced by laser ignition systems, following development of new manufacturing techniques by Japanese boffins. The new research is to be presented to the world at an optics conference in Baltimore next month by Takunori Taira of Japan's National Institutes of Natural Sciences and his …

COMMENTS

This topic is closed for new posts.

Page:

      1. Charles 9

        Sort of.

        The NOx comes mostly from incomplete combustion, which of course occurs more often with lean fuel. The idea is that the laser will be able to make the lean mix burn more completely. The end result is more boom and less NOx, basically.

        1. Jacob Lipman
          Alert

          Erm.

          "The NOx comes mostly from incomplete combustion, which of course occurs more often with lean fuel. The idea is that the laser will be able to make the lean mix burn more completely. The end result is more boom and less NOx, basically."

          That seems a bit counterintuitive. I'm not a combustion expert by any means, but it seems that a lean fuel mixture would mean more complete combustion, thus less crud. Shouldn't more oxidiser and less fuel mean thoroughly burned fuel and excess oxidiser?

      2. Anonymous Coward
        Anonymous Coward

        I am not an idiot.

        But I will admit that 'playing with them outside of the engine' was my first thought and the only reason I've read this far through the comments (other than for variations on 'sharks with lasers')

  1. Mystic Megabyte
    Flame

    meh!

    What happens when you get a bit of soot or other crap on the laser?

    "Sorry Guv' all your beams are knackered, that'll be £3000 to change'em thanks"

    BTW I work on engines that have £1200 injectors, each!

    1. Anonymous Coward
      Badgers

      Wow

      Them's some big injectors.

      Marine Diesel or Ferrari?

  2. Anonymous Coward
    Paris Hilton

    Where's the Paris joke?

    I'm sure she knows all about Squeeze, bang, blow, suck...

    1. Alister

      wrong order...

      for best results, as I'm sure she knows, it should be Suck, Squeeze, Bang, Blow.

      1. Anonymous Coward
        Dead Vulture

        Yes I know that...

        ...don't blame me if el-reg got it in the wrong order for their subtitle

        1. Steve Evans

          Re: Yes I know that...

          Nothing wrong with that... The order is fine.

          It's a repeating cycle, you just started off 180 degrees in.

          1. Alister

            Oh!...

            You're talking about engines...

            I was talking about Paris.

            Believe me, you don't want to start that cycle in the wrong place...

  3. Anonymous Coward
    Flame

    Ahh but the quick, dirty test will be great....

    ...so instead of pulling the plug out on it's HT (with decent gloves I may add) and sparking on the engine, do we now shoot lasers across the garage to see if it burns a hole in a plank of wood?

    1. Grease Monkey Silver badge

      Seriously

      When do you test your spark like this on a modern car? The last engine I did this on was an A series and lets be fair that wheezing, prehistoric, boat anchor would have been consigned to the garbage bin forty years ago were it not the power plant of the venerable Mini.

  4. Clive Mitchell
    Go

    I...

    ..just like the sub title!!

  5. GrinningGnome
    Boffin

    YAG - Science!

    Just wanted to point out YAG actually stands for Yttrium Aluminium Garnet. AFAIK Gallium has nothing to do with this stuff (see the conference abstracts!)

  6. lglethal Silver badge
    Pint

    Squeeze, -b-a-n-g- pew pew, blow, suck

    Best subtitle ive seen in ages! Top work Lewis!

    1. John Brown (no body) Silver badge
      Coat

      Squeeze, -b-a-n-g- pew pew, blow, suck

      I thought it was the names of the new SAS team assigned to Trumpton

  7. Anonymous Coward
    Anonymous Coward

    Lean Mixtures

    I've always been taught that once you get much leaner than something like 17:1 afr two things happen. Firstly the burn becomes less efficient and secondly the burn temperature goes up (not just the required spark temperature). The upshot being that you're not getting as much energy from your fuel as you would were the mixture richer and that you're not just talking about burning your plug electrodes, but other things in the combustion chamber, favourites probably being the exhaust valves. Then you end up having to use things like sodium cooled exhaust valves to stop them getting burned.

    Also I would have thought that the optimum afr was the one where there was exaclty the right amount of oxygen to burn the amount of fuel you had. Too little oxygen and you're getting unburned fuel coming out of the exhaust, to much oxygen and you're wasting energy compressing gas that isn't getting used. Actually that latter point always interested me because you're always wasting energy compressing a whole load of nitrogen that isn't getting used. If you could run your car on petrol and pure oxygen you would be running more efficiently because you wouldn't be wasting energy compressing all that pointless nitrogen.

    So there are two reasons a leaner mixture will produce less power per stroke than a richer one, firstly you're burning less fuel and secondly you're wasting your output power compressing unnecessary gas.

    If you want to burn less fuel use a smaller engine or possibly lower revs.

    1. amanfromearth
      Flame

      Stoichiometric

      yep, that's it..

      1. Anonymous Coward
        Anonymous Coward

        Not quite that simples

        Stochiometry - 14.7:1 air:fuel - is primarily needed because it's the only point at which catalytic converters are efficient. If it wasn't, then running leaner would give better economy, running richer better power. But - for closed-loop three-way precious-metal cats, 14.7:1 or Lambda 1.0 is king.

        Pity, really. Ricardo had 21:1 lean-burn running properly back in the early '90s, before cats were forced on us, helped immensely by the precious metals lobby. The drawback with that tech, though, was high NOx levels - and that's become more and more of an issue in recent years.

        So... How, exactly, will firing the mixture via raygun solve that issue? After all, it's not the spark plug that's currently restricting the mixture, but the emissions and legislation.

    2. Anonymous Coward
      Thumb Up

      Timing

      I would think that what they want to do is make the mixture much leaner as the engine speeds up into the upper rev range. You get more energy out of a richer mixture, but it may well burn more slowly.

      Leaner mixtures burn hotter because they burn faster.

      Engines get desperately inefficient at the top end of the rev range and the timings required to get it right become impossibly critical. This laser idea stands to improve the burn timing accuracy and efficiency at the top end of the rev range. If they can get this to work reliably and for a reasonable cost I can see potentially great gains from it.

    3. Bernd Felsche
      Boffin

      Almost...

      The leaner the AFR, the higher the combustion temperature and the propensity to form NOx emissions - which are the bug-bear of diesel engines.

      Now (cooled) EGR (Exhaust Gas Recirculation) can be used to reduce the effective displacement of the cylinder, substituting "dead air" having reduced O2 content for fresh air, so that NOx are less likely to be produced because there's more distance between available oxygen molecules and because the extra amount of "inert" gases requires more energy to heat up. Lean-running engines will always produce more NOx than those running stoichiometrically or rich. Modern diesel engines are meeting a similar challenge.

      NOx may be accummulated in a "catalyst" and when that's "full", sensed by NOx emissions post-catalyst rising, the engine management system causes the engine to run rich for a while, which provides for the release of the NOx and conversion via catalyst to N2 and O2 (as well as water and CO2).

      Spark-ignition engines solve the problem of igniting an overall-lean mixture by stratified charging; varying the rate of fuel delivery so that an easily-ignitable mixture is around the electrode(s) when the time comes. This is a "doddle" with diIrect injection.

      “Timing – quick combustion – is very important," should not be mis-interpreted. The idea is not to burn the fuel as rapidly as possible but to provide reliable ignition timing. An explosive burn would destroy an engine in minutes. The high-speed gas flow would strip the protective boundary layer of gases from metal surfaces, exposing them directly to temperatures that'll burn through the metal very quickly. (This is what happens during severe knock; a condition that is exascerbated by highcombustion temperatures.)

  8. Grease Monkey Silver badge

    Pints per Horsepower Hour

    The efficiency of an engine is best measured the old way, how much fuel it takes to produce so much power for so long. Pints per horsepower hour is the way we used to do it. Probably Kg per KWHour or something these days. Simply running leaner does not imply greater efficiency.

    Lets say a particular car needs 30hp to drive it down the road at 70mph. So to drive 70 miles at 70mph will take 30hp hours. Running leaner will not necessarilly mean it uses less fuel to do that work. It may be that running leaner means you need more throttle to achieve your 70mph - the upshot of which being of course you're using more fuel air mixture to produce the same power. That in turn could mean that you are using exactly the same amount of fuel as you were before, or if could mean you are using more.

    This reminds me of the stories about the magic carb that was killed off by the petrol companies. If you've never heard the tale, there was a story going round years ago that a carburettor was invented that would allow cars to run a lot leaner and hence use a lot less fuel, but produce as much power. However, the conspiracy theorists behind this tale believe that although this carburettor existed and was patented the petrol companies bought it up and stopped is being sold. Presumably they also managed to disappear the patent since no such patent exists. The stupid thing about this little story is that almost any carb can be set up to run leaner, but that will just mean that your fuel air mixture is too weak for the rest of your engine. The carbs (or these days the fuel injections) job is just to mix fuel and air, it's the engine itself that determines how well that is burned. However the myth still has a certain staying power and some continue to believe it. To those people I say get hold of a mappable ECU for any modern car and change the maps to make it run leaner and see what that does for you.

    The real advantages I see from this tech are (1) that you would no longer need to replace your plugs. Having said that plug life is getting longer and longer anyway. I remember having to swap plugs every six thousand miles. My current car needs new plugs only one tenth as often. Cheaper servicing would obviously result. and (2) if something went wrong you wouldn't end up foulling your plugs with excess fuel or other crud and your car would have more chance of starting in that situation.

  9. Nev
    Thumb Up

    Engines...

    ... with frikkin' laser beams attached to the frikkin' 'heads!

  10. John Dougald McCallum
    Flame

    Pure Oxygen & Petrol

    "If you could run your car on petrol and pure oxygen you would be running more efficiently because you wouldn't be wasting energy compressing all that pointless nitrogen."

    Doing this would certainly give you big bang followed by total silence unles you were running a gas turbine.

  11. John 62
    Flame

    solid state and very cheap?

    Laser igniters will probably end up as SFP modules that can be plugged into the space a spark plug used to occupy. It also remains to be seen whether they will become like CD player lasers that are so cheap they can be thrown into any CE device. How long will I have to wait to plug one into my 3.5 hp push Alba lawn mower? The spark plug has to be cleaned once or twice a year.

    (Yes, it is an Alba lawn mower. That's not the brand on the box, but the manual says the brand is owned by that venerable maker of cheap hi-fi kit and I since reading that I've never been able to remember the name of the brand)

  12. Anonymous Coward
    Anonymous Coward

    'Squeeze, bang pew pew, blow, suck'

    Oh Paris - is it you?

  13. Anonymous Coward
    Anonymous Coward

    Lasers

    Okay, this is a great application. But why am I still waiting for dental lasers to replace drills? This was promised when John Craven helmed the mighty 'Newsround' and still nothing.

  14. Franklin

    CVCC?

    Some while ago, Honda used CVCC (compound vortex controlled combustion) engines to run leaner without exotic sparking tech.

    Pretty easy; you have two fuel circuits. Each cylinder has another little tiny cylinder, with no piston, next to it. Lean mix goes in the main cylinder. Rich mix goes in the little one. Spark plug fires up the rich mix, which then spills into the main cylinder, igniting the lean mix therein. Result: Car runs leaner overall without the problems you normally get from that, fuel efficiency goes way up.

    It's a mature technology--my 1977 Honda Civic had it. Works very well, and another nice side effect is that it runs a whole lot cleaner, too. They used 'em for quite a while, through the late 80s at least and I think even into the 90s. Always wondered why that tech didn't catch on in a wider way.

  15. Jemma
    FAIL

    Taxi for Homer Simpson...

    1. The London taxi was designed with a petrol engine in mind and first produced with such (the 2.2 IOE smoke dispenser from the Landrover if I remember correctly, it certainly didnt dispense much power, I do know that). It took several models and in fact more than 2 manufacturers of Taxis before they came with the currently ubiquitous (and battlefield-smoke-screen enhanced) diesel that the majority of the FX4s still bumbling around are fitted with. Theyre easy to tell apart - one pukes out blue smoke, and the other pukes out soot like a extra from Mary Poppins. To be fair theres not so many of the Petrol FX4s about nowadays and they're all being gradually replaced by new models.

    2. Diesel is more efficient than petrol, true. Diesel is generally more reliable than petrol, also true, but ignore filters and the like at your peril with a diesel - anyone who has seen a compression ignition engine decide to eat its own lubrication oil and 'runaway' can attest to what an unpleasant and costly experience that is. Diesel however is heavier, slower revving and positively anemic at high revs. I also dont suggest being anywhere near a turbocharged/supercharged diesel if some idiot decides - rev limiter, whats one of thems then.... not to mention getting petrol-style high performance out of them is like getting honesty out of a politicians expenses.

    3. Lasers and piston crowns - I dont like where this is going - I can see a badly adjusted or incorrectly spec'ced laser igniter chewing its way through a piston crown and munching engines in short order - I could almost predict a Ro80 style - 'count how many engines I have detonated by the number of fingers I hold up' owners greeting on early cars fitted with this.

    4. Why hasn't anyone gone down the pressure scavenged two stroke route for modern cars - Chrysler almost did it with a two stroke Neon (they had a test mule running) - plus you get twice the power for a given displacement/tune - eg 2.2 Renault 12v douvrin engine - 136 to 272hp and thats not to add on the gains from a proper tuned pipe exhaust (another thing that Chrysler did waaaaaaay back in the 1950s, although they tuned the intakes). What a wonderful idea, a car the size of the Mundane-o with a 1100, 250+hp engine..

    Its all very well orgasming at the next idea to come out of Toyota or the like - or some think tank, but when you consider *why* we still use spark plugs and coil/coil(s) and the like, its very simple - it works, its generally reliable and its cheap and cost effective...

    more to the point just how long do you think it would take someone with a skull emptier than a chavs Brain-pan - to take one of the things out of a junked car, get a small 12v battery and go round blinding old people with it, cos they wont let him down the youff club - ASBO's are such a pain in the behind sometimes...

    Oh yeah, and the wonderful hybrids -

    Humber Sceptre - 1964 - 6 speed transmission - 100mph+ - 35mpg (with aerodynamics like a barn door with an obesity problem) - price now £2500

    Toyota Prius - 2011 - CVT (constantly vacuous transmission) - 99mph - 42-44mpg - not to mention all the pollution regarding the battery systems and transport before the thing even moves... £25000 plus however much it costs to replace the battery when it finally coughs.

    Its been calculated that if you ran something like the Sceptre from delivery new to now, doing an average mileage, driving reasonably and keeping everything tuned and in trim... you'd produce less pollution in 55 years, than is created just in manufacturing and transporting a Toyota Pious to a UK forecourt (not to mention that the Prius petrol engine is a less efficient Atkinson cycle motor, for a reason I have yet to fathom).

    Oh and multi valve heads - were being fitted to bugattis in the early 20's - and even cars in the Austin 7 racing series could be fitted with a multi valve head. Not to mention the Dolomite Sprint and all sorts of different machinery - its not a new concept. Pretty much nothing is. Oddly enough Ettore Bugatti left behind designs for a 22cc supercharged cycle-motor engine, that would fit, complete, into the palm of your hand, and put out a good 3-4 projected horsepower. thats 1hp per 6cc or the equivalent of 1000hp in a 6 litre engine... suck on that Veyron...

    There is little point adding more and more complication for complications sake. Oooh look, I can buy a Focus that can park itself, wonderful idea, until you fail your test because you actually have to be able to DRIVE!

  16. R.P.Charlie
    Boffin

    At the moment,

    as any automotive fule kno, the fuel-air mixture ....

    The Whaaat?

  17. zanto
    Dead Vulture

    an article on lasers

    without the word frikkin appearing even once?

    stick a fork in the reg, she's done

    i want my frikkin article on frikkin lazers done the frikkin el-reg frikkin way

  18. Alan Brown Silver badge

    lean burn....

    If you're running lean there's more oxygen to combine so combustion should be more complete. Most NoX emissions are a result of the higher temperatures involved (this is why aircooled engines are usually run rich - richer == cooler)

    Lean burn has been banned in the USA for years (there's legislation forcing stoichiometric mixtures) because of NoX emissions and they jump on it a lot harder than on this side of the pond.

    Utilising lean burn allows petrol engines to get very high mileage figures, so it's a pity there hasn't been enough research in this area in the last 20 years thanks to USA legistlators.

    Still, there are a huge number of areas where efficiencies can be increased.

    Dumping belt-driven accessories and substituting an exhaust-gas-driven alternator would help for starters (GM experimented with THAT in the 1930s, so there's plenty of prior art and no patents to have to deal with). On a similar note A/Cs can be driven from hot exhaust gases - https://secure.wikimedia.org/wikipedia/en/wiki/Absorption_refrigerator

  19. david 12 Silver badge

    NOx, Fractions

    You get NOx, Nitrogen Oxides, by burning the Nitrogen in air. This happens when you have a lean, high temperature combustion. If it's not lean, there is no excess Oxygen to combine with Nitrogen. If it's not hot, you can't burn. Lean means excess Oxygen, Rich means excess fuel.

    To limit NOx emission, modern engines burn a bit richer, and are a bit less efficient. So there is hydrocarbon polution in the exhaust. That's what the catalytic converter is for.

    The catalytic converter gets rid of the excess fuel in the exhaust, which is there because the engine burns rich to reduce NOx.

    In fact, an old, pre-pollution control, engine is more efficient than a modern efficient engine, because those engines burned leaner. And it wasn't particularly limited by spark plug design. Those old cars were less efficient, but that was because they had 3-speed gearboxes. Which is a different story.

    It may be that the spark plug is a limiting factor in pollution control, and an evener burn may let them make the overall mixture leaner. Certainly designing a cylinder to get an even burn is difficult, and pollution comes from hot spots and cold spots in the flame front.

    By the way, modern distilleries use high temperature "cracking" with catalysts to "crack" long-chain hydrocarbons (crude oil) into lighter fragments (octane, pentane, "petroleum"). The fractions that you get depend on the secret cracking recipe, not just on what you get out of the ground. So if the US is swapping diesel for petroleum, it's a complex economic and technical marketplace, not because they are pumping diesel out ot the ground

  20. Henry Wertz 1 Gold badge

    US diesel vehicles

    First, for whatever reason, diesel here costs more than gasoline for some reason. People are dumb, and don't realize a diesel will get so much higher MPG as to dwarf the small price difference.

    Second, gasoline here is relatively cheap (it's approaching $4 a gallon), and traditionally people here have not given a toss as much about MPG. It's fun now to poke fun at people that bought some horribly inefficient SUV or something a year or two ago, WHILE everyone was telling them gas prices would spike, and now they are bitching about gas prices being so high*.

    Third, the big push for diesels here was in the late 70s. Everything then ran horribly. But, we ended up with stuff like VW Diesel Rabbits, and GM made a few horrible diesels where they just took a gas V8 or V6 and upped the compression. They all barely could move, and smoked like crazy. People here think of this and of busses and semis (the local busses were VERY smokey until just a year or two ago, I think the city and University may have gotten new diesel mechanics.)

    Fourth factor now, EMISSIONS. VW has sold TDIs here for years, which are fabulous, but even had to pull those off the market for a few years because they couldn't meet emissions. We don't have quite the same standards for gas and diesel engines but diesel emissions aren't so lax as in other countrys.

    *On a side tangent -- we can finally get decent-MPG cars here within the last year or so, with more coming out as 2012 models. US'ians don't all want gas guzzlers, there was almost no choice in the matter. From the early 1990s to like 2011, if I had wanted a good-MPG vehicle, there was basically Geo Metro (before it went off the market in the mid-90s), Prius, a few years of the Honda Insight (before it also ballooned into the non-efficient vehicle they sell now), and various VW TDI models. THAT'S IT. Before the last year or so, there was this absurd feedback loop running for years. It went like this: Car companies looked at sales figures, they saw people with the cash buying larger cars, and cars with more power. Conclusion? For years, the larger vehicles and V6s have been tuned for mileage (tall cruising gears and whatever MPG-improving tricks they can put on), they'll get like 28-30MPG highway, and the few V8s will do at least 25MPG. Smaller vehicles? They'll take a model that gets good MPG everywhere else, decide it needs more power to have a chance to sell -- result, they lower the gearing, they soup up the engine at expense of MPG or entirely replace the engine with a US-specific one. They are sold at a low price so fuel-saving technologies may not be fitted to them. So you end up with a subcompact car that gets 30-32MPG highway. Which would you buy, a subcompact that gets 30MPG, or a larger, more powerful vehicle that ALSO gets 30MPG? They then looked at sales figures, rinse and repeat. FINALLY within the last year or so there's more 35-40+MPG models coming out, and not surprisingly they are selling great.

Page:

This topic is closed for new posts.