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Starter design

  1. Mar 31, 2004 #1
    My mind was wandering the other day in class, just after our physics teacher showed us the railgun he and his class made a while back. Anyway, I was wonder if you could use this principle in starting a gasoline engine. If you wrapped the electromagnetic coil around a cylinder, and fired it like you fired the rail gun for a short burst just to get the piston moving to the top of the cylinder. As i was typing i realized that the one cylinder wouldn't always be at bdc when you shut the car off. There would really be nothing to gain, but maybe space and weight. Just chuckin out there for yah to think about.
  2. jcsd
  3. Mar 31, 2004 #2
    Wouldn't that also take less power than the alternator currently does? Hence making the battery last longer?
  4. Mar 31, 2004 #3
    The alternator is not used as the starter. Some older cars used DC generators as starters, but now there is a distinct difference between the two.

    I don't see how this would save power. Also, another problem--How do you ensure the engine turns in the correct direction using your EM starter? Simply pushing down on a piston would not ensure the engine turns in the correct direction. Another thing is engines don't start on the first 1/2 revolution.
  5. Apr 1, 2004 #4


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    Engines use aluminum pistons. Last I checked, aluminum is not a magnetic material. At least not enough to do what you are describing.
  6. Apr 1, 2004 #5
    Everything will exibit magnetic properties. You just need a strong enough B-Field.

    Last edited: Apr 1, 2004
  7. Apr 19, 2004 #6
    This would present many problems. For one, how would you exactly mount this starter and where would it go? I don't think it could wrap around the cylinder necessarily. There wouldn't be room for it around a cylinder as for the size of the block and the nature of the engine block itself. Each cylinder is wrapped in a "water jacket" which uses water to cool the cylinder. Also, in addition to what faust9 said about the cylinder/crank position, there's also the issue of having enough power for the one cylinder to turn the crankshaft and all the other cylinders. The problem would be smaller in maybe a 3 or 4 cylinder engine because of the less inertia (less cylinders). If you tried it in an engine with more cylinders, it becomes a problem (such as a 6 or 8 cylinder).

    You probably already have a solution to all these problems, and if so you've done your homework well :biggrin: . Just wanted to maybe point these out. Good luck with that.
  8. Apr 19, 2004 #7


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    Seems unnecessarily complex, the current method is simple, effective and cheap. Not clear that this method will be able to compete.
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