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Sometime ago there was a discussion about engines in which it was proposed (jokingly) that the piston stay still while the block reciprocated violently up and down. It was just a joke but it got me thinking. What if the piston were stationary? The cylinder could reciprocate with a redesigned crankshaft.
The cylinder would be just that, an iron cylinder sealed and mounted to the crank via a bearing. The valves would be built into the piston heads. The piston would still need to move a few degrees, to the extent the crankshaft cam offsets. All intake and exhaust gases would be routed through the connecting rod and lead to the valves. Spark plugs would also protrude from the piston in this engine.
Advantages:
-Ability to change the angle in which power is transmitted to the crankshaft
-Even wear on piston ring seals
-Possibility of better ring seals, they can be larger now
Disadvantages:
-New cooling system must be invented
-Greater reciprocating weight on the crank
- Intake and exhaust gases would have to be routed through the piston connecting rod, which would have to move a few degrees off center
Bourke Engine.
http://i211.photobu...rk.gif?t=1193857887
Use a crank mechinism like this? [BJS, Oct 31 2007]
[link]
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addition: The connecting rod and piston would be one solid piece, no need for any movement between these two parts |
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Well it's certainly different, I'll give it that. |
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That's probably about all it will get... |
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Well, did you really think that people would think this is a "good" idea? |
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Im not an engineer, but I play one on the internet. I think that if built this engine would run. And hey BJ if I didn't think this was a good idea I wouldn't have wasted my time writing and posting it. |
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//Im not an engineer, but I play one on the internet.// |
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I'd bet that's true for a lot of us actually. |
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Why need a piston ? could the recipricating cylinder slide on the spark /valve mount block from the head ?
(the inside out piston) |
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Didn't radial engines in WW1 era airplanes (maybe areoplanes?) do this? The crankshaft (which was attached to the pistons) were attached to the nose of the plane, and the propeller was bolted to the block which spun around and around and around and around. |
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[crackpot] No, in that design there was still a traditional piston and connecting rod. The parts were "stationary" because the cyclinders rotated around the pistons. In my design the cylinder is mounted to the crankshaft. |
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And [wit] Its really not much of a piston as we define it right now. It would have to be cylindrical and have seals on its wall, but it could be any shape beyond the head. |
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By "good" I just mean more efficient in some way than what is currently available. |
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One of the problems with this engine is that there would be a big moving part out in the open. |
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This engine might not be such a bad idea with a few modifications. |
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I think the cylinders in this engine should be relatively 'short and fat' or have a large diameter with a short distance of travel. The valves should be as normal, with no intake and exhaust going through the same tube. The "piston heads" should actually "stay still" and not pivot, this can be accomplished in a number of different ways, but I'm thinking of something similar to the animation in the link. If it does not have to pivot, then it can more easily be enclosed, to make it safer and more reliable. |
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[BJS] intresting, short and fat would work just fine. I do believe this might be better that current engines because the angle in which the combustion force is transferred to the crankshaft can be changed, resulting in greater efficiency (sp?) |
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