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mogogear
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 Posted: Mon Apr 09, 2012 9:48 pm Post subject: |
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On HMEM....clues in the right direction?????
I found this reference to a the piston action we are all describing...I THINK..
Follow this link to the last post on the page by LESCAD...is this a lead towards hopefully a diagram somewhere?
http://www.homemodelenginemachinist.com/index.php?topic=15562.0
The engine pictured shows me nothing but the principle described sure seems close 
The 90 degree movement alluded to at the top of the linked page is more than we are wanting- but the arrangement that would produce this radial movement to a reciprocating piston
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mogogear
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| Posted: Mon Apr 09, 2012 11:21 pm Post subject: |
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Eureka..I think I have finally though the thought I wanted to think 
So what IF there were no Gudgeon pin? No perpendicular wrist pin? or at least none in the way we all usually think about.
What if all there really was to the "turning" mechanism was a projection or continuation of the connecting rod through the Ball joint at the top end of the rod??
As the crank would turn - this projection ( lever)would tip back and forth engaging internal lobes of the piston in a cavity just above the "ball joint".......
This would provide the leverage / fulcrum point to "tick" the piston back and forth in the bore as the crank shaft made each revolution??
I could be wrong - but this feels like the correct simplicity of design and feels so right- I cannot quite work out the lobe shapes inside the piston,.
I am close though- the lever tip just needs to encounter an incline to press against and that simple act will force the piston to turn, and the "tick back in the opposite direction would force the lever back against an opposite incline plane to move the piston in the opposite direction...
Like flipping a light switch back and forth
I could be wrong on if it is the tip of the rod , or something in this ball joint...It just feels so right......
The specific design detail of the lower "universal joint" type rod cap lends me to speculate. Once again this very subtle design quirk could be the mechanism and is one that lends itself to the type of engineer that Bryant could have been. He had a playfulness in the challenge for someone to guess how this worked and was most likely proud of the pure simplicity this little engine that could!
(Note- I intentionally did not draw in the lobes design for simplicity)
Ok- chew on that and see what the heads here think 
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Last edited by mogogear on Tue Apr 10, 2012 2:48 am; edited 6 times in total |
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WeedenSteam
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| Posted: Mon Apr 09, 2012 11:31 pm Post subject: |
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Mo, I think you may be on to something.
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Cowboy
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| Posted: Tue Apr 10, 2012 2:54 am Post subject: |
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| LOL. This has been a great thread. I like Jean-Yves' explanation because it just has a certain beauty to it, pure mechanical poetry. But mogogear's latest idea would be simple and effective. |
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Stoker
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| Posted: Tue Apr 10, 2012 3:35 am Post subject: |
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If your latest concept is on target Mo, then the underside of the piston head would want to have a small arc as the guide track, for the piston rod extension to rotate the piston.
Quarter circle for 90 degrees of rotation, but I think you could get away with far less and retain function, say 30 degrees perhaps!?!?
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mogogear
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| Posted: Tue Apr 10, 2012 4:04 am Post subject: |
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| Stoker wrote: | If your latest concept is on target Mo, then the underside of the piston head would want to have a small arc as the guide track, for the piston rod extension to rotate the piston.
Quarter circle for 90 degrees of rotation, but I think you could get away with far less and retain function, say 30 degrees perhaps!?!? |
Stoker-- I do not think a track is needed- The piston will follow the cylinder- the rod will stay straight due to the rod journal- as long as it is in the socket of the ball joint the force will just push the piston up. The piston in the bore will act as the guide.
So here is a mental picture to paint to you of the back and forth action..
1. I think there is a "wedge shaped" void for the tip of the lever to move back and forth in. With the tip near but not quite at the apex of the wedge.
2. So hold your fingers on your left hand like a peace sign- hold your hand flat while making the peace sign
3. now take the pointer finger on your other hand and while pointing your finger UP, place it in the "crotch" of the 2 'V'ed fingers-
4. Now rock your pointed finger back and forth- that is what I am seeing in my head that maybe the source of the rotation
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Stoker
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| Posted: Tue Apr 10, 2012 2:44 pm Post subject: |
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| mogogear wrote: | | Stoker wrote: | If your latest concept is on target Mo, then the underside of the piston head would want to have a small arc as the guide track, for the piston rod extension to rotate the piston.
Quarter circle for 90 degrees of rotation, but I think you could get away with far less and retain function, say 30 degrees perhaps!?!? |
Stoker-- I do not think a track is needed- The piston will follow the cylinder- the rod will stay straight due to the rod journal- as long as it is in the socket of the ball joint the force will just push the piston up. The piston in the bore will act as the guide.
So here is a mental picture to paint to you of the back and forth action..
1. I think there is a "wedge shaped" void for the tip of the lever to move back and forth in. With the tip near but not quite at the apex of the wedge.
2. So hold your fingers on your left hand like a peace sign- hold your hand flat while making the peace sign
3. now take the pointer finger on your other hand and while pointing your finger UP, place it in the "crotch" of the 2 'V'ed fingers-
4. Now rock your pointed finger back and forth- that is what I am seeing in my head that maybe the source of the rotation |
Let's see if I can clarify a bit here:
My arced "track" has nothing to do with guiding the piston up and down in the cylinder, but only in forcing the piston's rotation as the piston rod moves side to side away from TDC/BDC. In the same manner your wedge shaped void would qualify as a "V" shaped "track", but I believe that it's sharp angled interface may cause too abrupt a change in direction for the rotation of the piston within the cylinder. I may well be wrong of course, and perhaps my thought of an arc would provide too gentle of a transition and too slow of a rotation, thus an inefficiency cutoff.
My method should plot as a sine wave, while yours would plot more nearly as a square wave ... if I understand it correctly!?!?
As a possible engineering compromise, your "V" shaped track or guide, might transition more smoothly if there is a bit of a radius at the point of your "V" that is somewhat larger than the radius of the end of your piston rod extension that rides the guide.
Did that make any sense?
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Stoker
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| Posted: Tue Apr 10, 2012 2:54 pm Post subject: |
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| mogogear wrote: | | Stoker wrote: | If your latest concept is on target Mo, then the underside of the piston head would want to have a small arc as the guide track, for the piston rod extension to rotate the piston.
Quarter circle for 90 degrees of rotation, but I think you could get away with far less and retain function, say 30 degrees perhaps!?!? |
Stoker-- I do not think a track is needed- The piston will follow the cylinder- the rod will stay straight due to the rod journal- as long as it is in the socket of the ball joint the force will just push the piston up. The piston in the bore will act as the guide.
So here is a mental picture to paint to you of the back and forth action..
1. I think there is a "wedge shaped" void for the tip of the lever to move back and forth in. With the tip near but not quite at the apex of the wedge.
2. So hold your fingers on your left hand like a peace sign- hold your hand flat while making the peace sign
3. now take the pointer finger on your other hand and while pointing your finger UP, place it in the "crotch" of the 2 'V'ed fingers-
4. Now rock your pointed finger back and forth- that is what I am seeing in my head that maybe the source of the rotation |
Let's see if I can clarify a bit here:
My arc "track" (guide may be a better term) has nothing to do with guiding the piston up and down in the cylinder, but only in forcing the piston's rotation as the piston rod moves side to side away from TDC/BDC. In the same manner your wedge shaped void would qualify as a "V" shaped "track", but I believe that it's sharp angled interface may cause too abrupt a change in direction for the rotation of the piston within the cylinder. I may well be wrong of course, and perhaps my thought of an arc would provide too gentle of a transition and too slow of a rotation, thus an inefficiency cutoff.
My method should plot as a sine wave, while yours would plot more nearly as a square wave ... if I understand it correctly!?!?
As a possible engineering compromise, your "V" shaped track or guide, might transition more smoothly if there is a bit of a radius at the point of your "V" that is somewhat larger than the radius of the end of your piston rod extension that rides the guide.
Another way of looking at it is that the ends of my arc are essentially the same as the legs of your wedge, but we are transitioning between the two at different rates.
Did that make any sense?
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mogogear
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| Posted: Tue Apr 10, 2012 3:14 pm Post subject: |
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Daniel , by reading your description you are more studied and I just a brain -stormer...
Perhaps I understand-
The tip- top follows a almost S shaped groove? In poor layman's terms?
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Stoker
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| Posted: Tue Apr 10, 2012 3:20 pm Post subject: |
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Not an "S", but just a "C" as opposed to your wedge shape which would be a "<"
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mogogear
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| Posted: Tue Apr 10, 2012 3:33 pm Post subject: |
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| Stoker wrote: | | Not an "S", but just a "C" as opposed to your wedge shape which would be a "<" |
Ok - thick head now understands- I read "arc" and saw something else.
Of course this could still be all wrong and the original description of small pins in the ball joint may be causing this phenomenon ...and since that writer is far more knowledgeable than I - This has been an attempt to portray what was described or what was not accurately
described
An exercise in futility on my part I am afraid--Like Giovanni ( and others)- I too have always been intrigued by this engine...Daggnabbit
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Stoker
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| Posted: Tue Apr 10, 2012 4:21 pm Post subject: |
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Yep, it's all pretty hypothetical, but perhaps it could work ... maybe?!?!
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kno3
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| Posted: Tue Apr 10, 2012 7:36 pm Post subject: |
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Mo I think you are pretty close to the correct explanation.
It is what I was also trying to say on the first pageof this topic, but I'm not sure anybody else understood what I meant by:
| kno3 wrote: | ...
I assume the piston rod has a sort of protrusion (pin) that slides in a small curved channel inside the piston to make it turn a few degrees, but I might be wrong. |
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mogogear
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| Posted: Tue Apr 10, 2012 11:04 pm Post subject: |
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| kno3 wrote: | Mo I think you are pretty close to the correct explanation.
It is what I was also trying to say on the first pageof this topic, but I'm not sure anybody else understood what I meant by:
| kno3 wrote: | ...
I assume the piston rod has a sort of protrusion (pin) that slides in a small curved channel inside the piston to make it turn a few degrees, but I might be wrong. |
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Thanks and I appreciate your eyes ...On a side note I still like your boat. You have such a beautiful tug boat in your avatar-
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Dean W
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| Posted: Tue Apr 10, 2012 11:45 pm Post subject: |
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Just a suggestion, guys; Maybe over thinking this a bit. If the top end of the rod is a ball shape, and it has a small pin
through the center of the ball, all that is needed to rotate the piston in the cylinder bore would be a simple straight diagonal
slot in either the side of the piston, or the carrier for the "ball end" of the con rod. As the rod travels up and down, that pin
will rotate the piston simply by traversing up and down that diagonal slot. The side-to-side swing of the rod changes the
position of the end of that little rod.
Sez me, anyway. It's easy enough to be wrong about this whole thing.
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