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  • Crank-less Motion Converter

    Discussion in 'Your mechanical design work' started by OtR, Sep 12, 2013.

    1. OtR

      OtR Member

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      [video=youtube_share;mdcYTbnT3iE]http://youtu.be/mdcYTbnT3iE[/video]

      This was designed for converting bidirectional rotary motion from a pendulum type engine to unidirectional rotary output. It seems to have very high mechanical advantage throughout the oscillations. Conventional crank and slider type engines have poor mechanical advantage when the pressure on the pistons is highest. This should yield much better fuel efficiency.

      This simulation shows concept only. Actual production can have extra gears or can be gear-less, but using the same concept.
       
      Last edited: Sep 12, 2013
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    3. mechaboy

      mechaboy Active Member

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      thank's for this interesting mechanism
      that's incredible!:eek:
       
    4. OtR

      OtR Member

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      I have good hopes for it. My next step is to have it evaluated to verify the efficiency that I am convinced it has. Trying to make the right connections seems to be a little slow.
       
    5. mechaboy

      mechaboy Active Member

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      did you make any prototype?
       
    6. OtR

      OtR Member

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      I had one made. It is shown in the upper corner where I am turning the oscillating shaft back and forth and the other is rotating.
       
    7. mechaboy

      mechaboy Active Member

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      so that was you
      how you analysed it's dynamics?
      can it work reverse?
       
    8. OtR

      OtR Member

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      Yes, it can work in reverse (rotary to oscillating rotary). Also, if you hold what would be the rotary shaft still and rotate the housing, the other shaft rotates one direction with a momentary dwell, smoothly accelerating and decelerating to and from dwell.

      First, analyzing was mental while it was just concept. Then I spent much time making a model in Google Sketchup with Sketchyphysics to show dynamics. I was satisfied enough with the results to have the prototype made, besides doing patent applications. I have the Solid Works files which should allow motion studies, and I think they could have included those studies so I could view them in e-drawings, but I haven't been able to find them with e-drawings.

      So my next study of the dynamics was handling the prototype. I can see that it acts as I expected. There is what could be compared to a top and bottom dead center where force applied to the oscillating shaft doesn't have much effect to rotary shaft, but that is momentary. As soon as you get past that momentary spot, force applied has good effect to turning the rotary. It is what I expect by watching the simulation. The oscillating shaft quickly gets up to speed and is fairly constant through the oscillation. The torque that I feel with the prototype seems to relate to that. Torque is high at the points of changing direction but quickly becomes near constant until close to changing direction again. The closer to the same size the two gear sets, the quicker the oscillating shaft will change direction and the more steady the torque in/torque out. The pulley on the rotary shaft acts somewhat as a flywheel to help it go past the dead spot and its kinetic energy is reintroduced into the other direction.

      The animation I used in the video starting this thread was made with the Phun simulator, a free download. With it I can display the critical values which include the forces and velocities of the various parts. Those values change so fast, it is hard to read them. I though of making a screen recording and slowing it down, but I was satisfied that what I was seeing was what I would expect.

      I wish I had the motion studies that should go along with the Solid Works assembly file, but again, I feel it would only confirm things. I put in a submission to a university to ask them to do a study on it, but so far they haven't responded. If an engineer or university would validate the dynamics and feasibility, it could make it easier to find interest in taking it to market.
       
    9. mechaboy

      mechaboy Active Member

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      hi
      thank's a lot for your great explanation.
      i believe that you will be successful in the market.as a suggestion i think you need show your patent in redesigning the existing machines.like machines that work with crank rocker some forge hammers or saws.then i would be interesting for market.
       
    10. mechaboy

      mechaboy Active Member

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      i have question about google sketch up and Sketchyphysics,are the free?
      are they easy to learn?
       
    11. OtR

      OtR Member

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      They are free, but there is a Pro version of Sketchup with additional features. I didn't use the pro version. I don't think it had anything to help me anyway. Sketchup is pretty easy to learn, but you have better control over what you are doing with other software. Sketchyphysics is a plugin to give you the physics engine. I had plenty of problems with that plugin. My biggest problems were that joints are easily broken when you edit, and then it is hard to tell what is broken. I found it best to make sure I had a clean model saved with no physics joints before adding joints. When making changes to the model, I usually went back to the clean model, or I would have been better off anyway. It was easier to add the joints again than to fix what was broken.

      I am including a link to a short video clip that I made using Sketchup before having the prototype made. Afterward I found the Phun simulator, which is also free. I spent a lot less time using it to make the video that I originally posted. The main disadvantage of the Phun simulator is that it is two dimensional rather than 3D. Which you are better off with depends on your needs. All I really needed was the 2D and it was much easier.

      Notice in the attached clip from Sketchup, only the teeth are shown. It also makes the important parts more visible, but the main reason for only showing the teeth is that each tooth had to be made individually so a mesh could wrap around it for the physics engine to recognize the contact surfaces. The mesh won't wrap around a gear to make this happen. Then all the teeth were grouped after the teeth were turned into convexhull. It was a lot of work.

      [video=youtube_share;JXIONHDso7U]http://youtu.be/JXIONHDso7U[/video]
       

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