Home made, Air compressor to gas engine throttle control

Discussion in 'All Things Boats & Boating' started by thudpucker, Jun 3, 2013.

  1. thudpucker
    Joined: Jul 2007
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    thudpucker Senior Member

    I have a couple tanks, some compressors and a few little gas engines.
    I set up a gas engine, a compressor, on a tank.
    Now I need to invent a Throttle control so the engine shuts down to Idle, when the Pop-off goes, and when the air pressure goes down below 90, the engine goes to hi-throttle.

    I know we can buy those, but I want to make one. Has anybody ever done that?
    Got some info for me?
    Old compressor 2.jpg
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Air cooled engines like that usually use a governor that runs off the air flow. However, because a compressor puts a huge load, to prevent the engine from stalling it will probably need to be set up so the pressure is really low before it kicks in.
     
  3. jonr
    Joined: Sep 2008
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    jonr Senior Member

    So some kind of small piston that pushes against a spring and moves a lever (or cable). These small engines usually have a flat torque curve, so you may have adequate torque, even at idle rpm.
     
  4. CDK
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    CDK retired engineer

    No electricity I presume, so use a small pneumatic cylinder with a coil spring added between piston and top cover.
     
  5. thudpucker
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    thudpucker Senior Member

    So far CDK is closest.
    The 'stuff' I have left is a popoff valve for the tank or pump that shoots off at 90 Lbs.
    I think I can use that 'shaft' of the valve to trip a switch or trip a ' PT PAIR' (transistor switch) and that will pull a solenoid which takes the engine down to Idle.
    Not much of a problem there.

    So now to the hard part of the problem. When the air pressure drops to 60 Lbs, the Popoff has already oozed back into it's HideyHole, I need something to fire up the Gasoline engine.
    Something like a Popoff valve that finally drops out at 60Lbs.

    I've never seen the 'real thing' nor seen an explanation of how it works.
     
  6. whitepointer23

    whitepointer23 Previous Member

    type air compressor throttle control for petrol engine into google and you will see a good video explaining the process.
     
  7. CDK
    Joined: Aug 2007
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    CDK retired engineer

    The small cylinder (or an automotive vacuum actuator) forces the throttle open when air pressure is near or below 60 lbs. With increasing pressure the rod/shaft moves out but the throttle stays open (friction washer or a notch) until maximum pressure is reached and a lever pushes the throttle back to idle.
    The trick here is to create enough slack so no action is taken between min. and max. pressure. Two pop0ff valves, one normal, one modified for low pressure can also do the job.
     
  8. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You can use an air servo. If the tank is completely empty, the engine can start at slow idle, but if there is pressure and the compressor has to start with a load, it will accelerate more. Also, there are usually decompressing valves added to make the first stroke in the compressor easier.
     

  9. thudpucker
    Joined: Jul 2007
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    Location: Al.

    thudpucker Senior Member

    Thanks CDK.
    I'm always glad to get the opinions of the Tech's on this board.

    PS: We were without the Internet for almost three days, because Storms blocked the Satellite dish.
    I wonder if them Texans are aware of the trouble we face as they are sending all those clouds our way? :)
     
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