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A gearing problem!

  1. Aug 23, 2009 #1
    Does anyone know of any gearing assemply like what I am looking for - - - sort of the opposite of a Geneva Mechanism. It would have a drive that, during the first four 90 degree increments of the input, the output also increments in 90 degree intervals. In the fifth and sixth 90 degree increments (540 degrees total) of the input, the output is held stationary. In essence, 360 degrees out for every 540 degrees in).

    An alternative would be for 180 degrees out for every 270 degrees in. Thanks.

  2. jcsd
  3. Aug 24, 2009 #2
    What level of power (watts or HP) are you talking about and what RPM? You maybe could use a microprocessor and a stepping motor.
  4. Aug 24, 2009 #3
    Looking for relatively large power handling capacity. It should be mechanical, and hopefully relatively efficient. To be sure, it's a mind experiment prompted by one of your other links - - - on torodal engines.

  5. Aug 24, 2009 #4


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    I'll have to think on this for a while, since I'm well into the Scotch right now (my wife drank all of my beer). It seems to me, offhand, that it could be achieved with either a cam or an interrupted gear.
    You mentioned that the output is to be held during the non-driven phase. Do you mean just not driven, or do you have to somehow lock it into position?
  6. Aug 25, 2009 #5

    It needs to be locked. It can't float free.

  7. Aug 25, 2009 #6


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    Is there power and space available to put an electromagnetic brake on the shaft?
  8. Aug 26, 2009 #7
    Maybe you could use some sort of worm gear? perhaps from a windshield wiper motor or something. pulse the motor on and off with a microcontroller for stop/start times and the worm gear assembly will keep the output shaft from loosing it's position.
  9. Aug 26, 2009 #8
    The answer is probably yes, but I think a mechanical solution would be better.

  10. Aug 26, 2009 #9
    I don't think so. It should be an integral part of the mechanism itself.

  11. Aug 26, 2009 #10
    I'm going to try to put up a description of the concept itself. It was suggested by another string - - - a toroidal engine ides. It's just an idea exercise.

  12. Aug 26, 2009 #11
    I'm going to try to put up a description of the concept itself. It was suggested by another string - - - a toroidal engine ides. It's just an idea exercise.

  13. Aug 26, 2009 #12


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    Hmmm.... I thought that the worm gear was a damned good idea, but if you don't want to pulse the motor...
    Maybe a combination of an interrupted gear and a cam? When the non-toothed section of the gear gets to the driven gear, the cam applies a mechanical braking force to the driven shaft. If they're on the same driveshaft, they should remain synchronized.

    edit: You could also use an interrupted gear to drive a worm gear. That might be the best of both worlds.
    Last edited: Aug 26, 2009
  14. Aug 27, 2009 #13
    Actually, the gear/cam arrangement sounds pretty good to me. It would appear to have a faster response than a worm drive. Also the action appears more bi-directional. I'll try to supply some sketches of the envisioned toroidal system's operation soon. That might give an idea of what is needed.

  15. Aug 27, 2009 #14


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    That would be very helpful. It's a bit difficult to give design advice without knowing the intended goal.
  16. Aug 27, 2009 #15
    I have the drawings, but need to convert them. I should have them by tomorrow.

  17. Aug 28, 2009 #16


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    It just occurred to me (duh...) that the interrupted gear and the cam can actually be the same piece, rather than two separate ones on the same shaft. Don't know why the hell I didn't think of that the first time around. (Oh, yeah... Scotch...) :rolleyes:
  18. Aug 28, 2009 #17
  19. Aug 28, 2009 #18
    The engine shown in the accompanying drawings can be either Otto Cycle or Diesel cycle, and is equivalent to an eight-cylinder reciprocating engine since a cycle takes only one revolution. Only one chamber (volume between pistons) will be described, although there are four. A full four cycle operation takes place in each chamber with each revolution. Pistons can only move in a forward direction (clockwise), though each will be intermittently stopped. The following ten steps are taken to describe one full cycle: (Refer to plates 1 through 4.)

    A. In the first phase, for the chamber we are examining, at the start the pistons are together. Both pistons are in motion, but the trailing one is stopped here.

    B. (Intake Phase) The lead piston (yellow) is moving and the trailing piston (rose) is stopped.

    C. Continuation of intake. Here, the piston ahead of the chamber (yellow) continues moving, and the piston that it has just overtaken (rose) is just starting. Here, the chamber is filled.

    D. Here, all pistons move together, until they reach the point shown, and the piston ahead of the intaken air (yellow) stops.

    E. (Compression Phase) Here, the piston following the intaken air (rose) continues, compressing the charge.

    F. At this point, the compression phase is complete, and the piston ahead of the charge (yellow) starts to move again. The two pistons are now moving together.

    G. (Ignition Phase) The two pistons continue until they reach the spark plug/injector. Here, the piston that is now trailing (rose) stops and the plug fires or the newly injected fuel pressure ignites.

    H. (Expansion Phase) Only the lead piston (yellow) is here allowed to move. The expanding gas forces it ahead.

    J. Expansion continues until the lead piston (yellow) reaches the one ahead of it (rose) which then starts to move, along with the piston behind the expansion chamber (also rose).

    K. (Exhaust Phase Start) All the pistons move until the exhaust port is uncovered and exhaust starts. Then the piston (yellow) ahead of the chamber under discussion stops, while the following piston (rose) continues, forcing the gasses out.

    L. The exhaust purge continues.

    M. When exhaust has ended, the lead piston (yellow) and the trailing piston (rose) are together, and the lead piston again starts moving, while the trailing piston continues moving.

    N. Both pistons continue moving until the starting position is again reached. Here the trailing piston (rose) stops, and the cycle starts again.

    P. This is simply a typical view showing operation in all chambers at one point in time.

    This is the application which I described as needing the "gearing assembly", to cause the pistons to start and stop when needed. Obviously the gearing has to be robust, because this is a power device, and it has to be fast acting. This is why I think a mechanical linkage is preferable. It should also have inherent feedback (bi-directional action) since it will go to drive the pistons, be driven by the pistons and ultimately drive the output. Finally, I feel that I must tell what I plan for this engine in this configuration. The answer - - - absolutely nothing! It is a thought exercise only, open to anyone interested. I think, however, that this approach is superior to any that we have seen, so far. Caveat: This configuration has the same drawbacks as all toroidal engines: 1) Because it is sealed, it cannot keep lubricating oil from mixing with the working fluids, and 2) It will be tricky to seal at its base (but easier than the Wankel), which makes it problematic for consumer automobiles (pollution??). On the other hand, it is probably quite suitable for racing vehicles, helicopters, speedboats and items like that.

    (The last two figures are in the following insertion)


    Attached Files:

  20. Aug 28, 2009 #19
    "The figures that were omitted."

    Attached Files:

  21. Aug 28, 2009 #20
    What I envision is a gearing something like the following:

    Attached Files:

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