Half a croissant, on a plate, with a sign in front of it saying '50c'
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Piezo Electric Spark Plug

Piezo ignited spark
  [vote for,

No more need for distributors - a piezo powered spark plug would be mechanically timed to produce the spark when piston reaches top. In fact you could do away with the battery entirely - this would be good in 50cc kick start mopeds - lower manufacturing costs.
ajwhunter, Nov 13 2002

Bammer http://www.internat...com/toolgurufeb.htm
Piezo Spark Plug Nail Gun [thumbwax, Oct 04 2004, last modified Oct 21 2004]

Magneto ignition system http://www.old-engine.com/maghma.htm
[half, Oct 04 2004, last modified Oct 21 2004]

Model engine with stove-lighter ignition http://www.ministea...talog/1sleftbig.jpg
You can buy one... [windmill, Oct 31 2004]


       Interesting twist with the piezo but, you're basically talking about a magneto. I suppose it would be lighter than a mag though. What I don't know is if a piezo source will fire a spark plug under combustion chamber conditions. Anyone?   

       To be technical, a 50cc single cylinder engine isn't going to have a distributor.   

       (Spark plugs don't generally fire when the piston is at top dead center but I get your meaning)   

       Electronic distributorless ignition systems are quite baked (not piezo, as far as I know).   

       I've 50cc kick start "mini-bikes" with no battery.   

       Sorry, I can't find anything croissant-able on this.
half, Nov 13 2002

       An honestly good effort into exploring alternatives, but not scientifically workable. Piezoelectrics won't provide nearly the juice needed, even if you could get the timing right. Er wait, are you powering the spark with the piezo, or just timing it?
RayfordSteele, Nov 13 2002

       I do have to admit that it might make an interesting racket on a V8 if each one of the ignitors sounded like the one on my gas barbecue grill.
half, Nov 13 2002

       piezo electric ignitions are still good for shocking first years:)
starman, Nov 14 2002

       // Piezoelectrics won't provide nearly the juice needed //   

       I'm not sure about that. Some of the piezo systems I've seen generate pretty impressive sparks.   

       I have this vision of a sort of automated xylophone of little trip hammers on top of the engine, all banging away at the tops of the spark plugs ... or a sort of camshaft.   

       The great advantage of this idea - if it can be made to work - is you can create an (almost) purely mechanical engine, effectively a "diesel" design. That might have important reliability gains for things like aero engines - and save weight.   

       I'd like to see this tried on a model aircraft scale, where the weight penalty of an eletrical ignition system would be significant.   

       Now just wating for FarmerJohn to come along and suggest screwing a huge lightning rod to the car ...
8th of 7, Nov 14 2002

       Magneto vs Piezo was a rad comic book.
rapid transit, May 20 2003

       Since piezo gadgets are pressure-activated, consider putting the piezo crystal INSIDE the cylinder. Then the compression stroke that squeezes the fuel-air mix will also (second-hand) be squeezing the crystal, and if planned right, near Top Dead Center, spark happens! Natually, the explosion counts as even more squeeze, so maybe some extra sparks will occur in the cylinder. That would be good to help prevent pollution.
Vernon, Jun 16 2003

       A piezo-electric voltage source could certainly work in an internal combustion engine. A major problem with the concept, though, is that such things can wear out. Wear isn't apt to be a problem in a stove lighter that may get whacked a few thousand times in the course of its useful life. Something in an engine which gets whacked thousands of times every minute, though, would be another story.
supercat, Jun 16 2003

       good ideal in therory but how do you advance and retard the timming? the speed at which the fuel air mixture burns is constant as piston speed increases (engine rpm) the mixture must be ignited sooner so combustion will take place at tdc of the stroke or just past.   

       taking this into account the mechanics to make this work would be ovely complicated compared to mag or convetional coil ignition
matthewq4b, Aug 15 2003

       my uncle built such a thing with piezo and it was very compact ,the only problem is that it would on work on a small moped engine there was too much lag in the mechanism to be reset fast enough to hit the piezo at high revs at low speeds though it worked great. he basically drilled a hole in the spark plug and welded a tube that brought pressure to a slice of a 50 cc piston which in turn had a mechanism to hit the piezo, he built many variations but couldn't get rid of the lag for high revs.
mawgadog, Jul 06 2004

       // The great advantage of this idea - if it can be made to work - is you can create an (almost) purely mechanical engine, effectively a "diesel" design. That might have important reliability gains for things like aero engines - and save weight. // [8th of 7]   

       Actually, this is a disadvantage. Mechanical systems usually have much less reliability than purely electrical systems. That's why cars have been moving away from mechanical methods such as points and distributors.
GenYus, Jul 06 2004

       Piezo electric devices lose their ability to generate high voltages over time. The loss is accelerated with elevated temperatures, too.   

       The ignition timing moves around quite a lot on modern gasoline engines, depending upon conditions. Cruising at highway speeds the timing is advanced as much as 40 degrees before top dead center BTDC). Under wide open throttle conditions the timing drops back to about 20 degrees (BTDC). At idle it is closer to 5 degrees (or so) BTDC. The need to alter the spark timing complicates an all-mechanical design, not to mention the reduced heat-realated life expectancy of a piezo-electric "sparker".
ricks, Sep 01 2004

       Good idea, and feasable. Imagine an extra sparkplug protuding from the cylinderhead so the piston hits a plunger (placed like the central electrode on a conventional spark plug) when it's at 30º advance. It then produces a high tension voltage, canalized to a true sparkplug. This way, the quartz is not submitted to any specially high temprature, and the system does away with a lot of thingamagins. There's a lot to speak about reliabilty of the modern electronical systems against the old point ignition system. I use points on all my planes. Why?. Bun bunbun.
finflazo, Sep 01 2004

       A friend that had built model, running , gas engines used piezoelectric ignition. It matched the engines sizewise. I would think variable timing would be the greatest difficulty. DIS ignitions put very little strain on an engine, but would still require a battery.
bammer, Dec 06 2004

       if it did work i would still rather have a battery powered car because i like listening to music
demononwheels, Feb 27 2006

       so your thinking to have an electrode on the piston and one on the head and when they get close the make a spark? yeah i dont want to burst your bubble but ill go ahead here it is- replacing it would be a hassle
permafried, Nov 03 2011

       Something about this idea seems to have attracted a lot of people with substandard grammar skills.
notexactly, Apr 22 2018


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