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Looking for (automotive?) servo to actuate a throttle

Discussion in 'Misc Electronics' started by Scott Kelley, Sep 7, 2005.

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  1. Scott Kelley

    Scott Kelley Guest

    I need a fairly heavy duty servo unit (Stepper, or DC with feedback) to
    operate the throttle on an
    engine.

    The catch is that it must have to have an electrically operated clutch to
    allow it to be fully disconnected.

    I can imagine that there may be some automotive cruise control units that
    would work, but I am not at all familiar with what is out there. Any
    thoughts?

    Thx
    Scott Kelley
     
  2. Jasen Betts

    Jasen Betts Guest

    I think most cruise control units only push on the throttle lever
    and when they "disconnect" they leave just back off and leave the
    throttle under the control of the pedal.

    maybe you could do the same?

    . . . . . . . . . . . . .

    rest/ilde
    return spring (optional)
    ||///////////////|#
    manual control-------------+
    |><|------------------ to throttle butterfly
    |
    servo control -------------|><||//////////////|#
    throttle return spring


    . . . . . . . . . . . . .

    manual control operated
    return spring (optional)
    ||///////|#
    manual control---------------------+
    |><|---------- to throttle butterfly
    |
    servo control -------------|> <||//////|#
    throttle return spring


    . . . . . . . . . . . . .

    servo operated
    return spring (optional)
    ||///////////////|#
    manual control-------------+
    |> <|---------- to throttle butterfly
    |
    servo control ---------------------|><||//////|#
    throttle return spring


    . . . . . . . . . . . . .


    the throttle rreturn spring is a light duty spring just sufficient to close
    the throttle, this means that only a small servo is needed to oppose the
    spring. the return spring for the manual control is onlt needed to pullt
    the throttle cable, lift the pedal etc, if you're intending some other sort
    of manual control it's not needed.


    on the other hand stepper motors have only low torque when not powered
    maybe the torque would be low enough so as not to need to de-clutch it.

    a stepper motor with electromagnet field (instead of permanent magnet) has
    no torque when not powered, I'm not sure of their availability
    a selsyn type actuator could be possibly be used here but fed with a DC field
    instead of AC and treated as a 3-phase stepper.


    Bye.
    Jasen
     
  3. John

    John Guest

    Many cruise control units have a vacuum servo to move the throttle.
    If you want a true clutch mechanism, perhaps a magnetic clutch would
    work - it only provides a connection when energized.
    John
     
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