h a l f b a k e r yIncidentally, why isn't "spacecraft" another word for "interior design"?
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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.
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]
[link]
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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? |
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To be technical, a 50cc single cylinder engine isn't going to have a distributor. |
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(Spark plugs don't generally fire when the piston is at top dead center but I get your meaning) |
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Electronic distributorless ignition systems are quite baked (not piezo, as far as I know). |
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I've 50cc kick start "mini-bikes" with no battery. |
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Sorry, I can't find anything croissant-able on this. |
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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? |
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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. |
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piezo electric ignitions are still good for shocking first years:) |
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// Piezoelectrics won't provide nearly the juice needed // |
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I'm not sure about that. Some of the piezo systems I've seen generate pretty impressive sparks. |
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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. |
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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. |
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I'd like to see this tried on a model aircraft scale, where the weight penalty of an eletrical ignition system would be significant. |
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Now just wating for FarmerJohn to come along and suggest screwing a huge lightning rod to the car ... |
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Magneto vs Piezo was a rad comic book. |
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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. |
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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. |
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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. |
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taking this into account the mechanics to make this work would be ovely complicated compared to mag or convetional coil ignition |
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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. |
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// 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] |
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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. |
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Piezo electric devices lose their ability to generate high voltages over time. The loss is accelerated with elevated temperatures, too. |
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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". |
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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. |
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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. |
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if it did work i would still rather have a battery powered car because i like listening to music |
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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 |
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Something about this idea seems to have attracted a lot of
people with substandard grammar skills. |
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