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Hydraulic engine

  1. Mar 22, 2006 #1


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    Imagine a bar, say 3inches dia by 15inches long, the bar is turned down to
    1inch dia 3inches in for 3inches, and again at 9 inches for three inches, this
    forms 3, connected (pistons), this piston assembly is enclosed in a cylinder
    the outer pistons are moved by internal combustion using the 2 stroke principle,
    the inner piston is used as a hydrulic pump, when say the right cylinder fires, a valve opens
    on the left of the centeral pump piston, and the reverse as the left cylinder fires, the hydraulic pressure is such that it will not allow the ic pistons to (bottom out), thus forming
    a hydraulic motor with only one moving part, will it work.
    Second draft as first was nonsence.
    Last edited: Mar 22, 2006
  2. jcsd
  3. Mar 22, 2006 #2


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    Sounds like a bad impedance mismatch, the viscosity of the hydraulic fluid is many times that of the air. Since a 2-cycle engine can maybe operate at 1200 RPM, then you're asking the fluid to pump at 20 Hz and you have a gas pressure of something like 1000psi for 5msec and a mechanical ratio of 1:1.

    Maybe if you reduced the volume in the hydraulic areas you could gain more mechanical advantage, but the moving mass would still be quite large and getting the balance correct for operation sounds difficult.

    A 2-cycle needs the downstroke of the piston to compress the mixture in the crankcase so that when it uncovers the intake port the mixture can be introduced. You're sort of trying to use that to pressurize hydraulic fluid, so where is the pressurized mixture coming from?

    And how would you start this thing??? :smile:
  4. Mar 22, 2006 #3


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    OOps, silly idea any way. LOL
  5. Mar 23, 2006 #4


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    You could, however, use your design as an air pump to pressurize a bladder-type hydraulic accumulator. You'd probably need some kind of air-bleed valve in the system to prevent over-pressurization or stalling the engine.
  6. Apr 3, 2006 #5
    Sounds like a multi-stage piston as is used in some air compressors.
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