vibration dampenning

Discussion in 'GEO / Suzuki' started by glenschweizer, Jul 19, 2012.

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  1. Jul 19, 2012 #1

    glenschweizer

    glenschweizer

    glenschweizer

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    when considering conversion, vibration dampenning is obviously one of many important issues to consider, so I pose this question: shouldn't we use combined mass of the clutch disc and pressure plate as installed on the original engine together with an original flywheel in aircraft applications as well? Maybe even using the clutch disc whith it's spring dampenning system and input shaft from the trans through a redrive. I've read that the 3 cyl. geo has some ugly torsional vibrations at 1700, 3400 and 5100 RPM. I found it curious that the vibe monster reared its ugly head at those ranges. I understand the weight penalty, but if that could taim the monster, it may be worth it. Any thoughts?
     
  2. Jul 19, 2012 #2

    Topaz

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    There are quite a few discussions here that you can peruse for more information. Use the search function with the term, "torsional vibration" or "torsional resonance". That should turn up most of them.

    The basic issue is that the engine-propeller system has very different torsional resonance characteristics than an engine-driveline-wheels system. Even including all the original flywheel, etc., is no cure, since the resonance points are going to be vastly different when it's a prop bolted to the engine instead of wheels that are firmly on the ground at all times.
     
  3. Jul 19, 2012 #3

    clanon

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    Well ,that could be useful ...to know the exact frequencies of resonance (28.33hz ; 56.66hz and 85hz) you could tune your system to reduce those (custom made dampening)... right?
     
  4. Jul 19, 2012 #4

    Topaz

    Topaz

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    Like I said, run a search - all of this has been discussed here, in depth, quite a number of times.
     
  5. Aug 4, 2012 #5

    raven-rotor

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    Glen

    Flywheel mass will obviously smooth out the low end idle piston pulses, but the whole subject of torsional resonance is well beyond the range of what we could call 'common sense' solutions. What creates resonance is the similar mass moments between the engine and its rotating components and the propeller with the redrive stuck in between. When resonance occurs and begins to build we have captured a tidal wave of energy in the redrive and something has to give. Springs can just make it worse, rubber by itself can change the frequency and move the resonance out of the operating range (al la the Rotax® rubber donut) but it doesn't allow the engine to idle slowly or smoothly like it would in the car. We spent years testing and developing a redrive that would allow the Geo 3 cylinder to idle smoothly at 1050-1100 RPM and run without damage in the primary resonance range of 1550-1800 RPM. I am stubborn and would simply not give up and still have a pile of all the scrap parts, components, and common sense ideas that did NOT work. Hope this helps.

    Jeron Smith
    Raven ReDrives Inc.
     

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