Hi,
Quote:
Originally Posted by cr45
Relative to the pistons being at tdc, at what stage in the cycle is the fresh charged introduced?
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The intake valve (two openings in the disk valve) would have to be right after TDC, I would imagine? The challenge would be to have the exhaust ports open as close up to TDC as possible. This is obviously very schematic -- a thought experiment to see if such a thing is feasible.
Whether or not it works, all depends on whether the expansion from just burning the fuel is enough to power the engine; balanced against the parasitic losses. Since it is a 2-stroke, there is only one "coasting" stroke; rather than three, and no compression which has to be a big savings. And rotary valves are much lower friction -- just a constant low drag rather than periodic peaks when the cam lobes have to push against the valve springs.
Edit: some further thoughts on the compression stroke. If the compression in and of itself is important, then this design is probably moot; but here is why it seems like it is about the heat generated by the compression and not the compression itself, per se. The compression itself is all done at a loss by using the momentum of the flywheel, and because there is friction loss as well, the compression itself can't be worthwhile -- the net gain must be coming from the fuel burn.
If it is the heat gain during compression that is important -- think about this: there is some much excess heat in ICE's as it is, right? If that "waste" heat could be transferred to the intake air *instead* of having to heat it via compression -- then we gain a whole lot of efficiency, right?
The intake manifold passages could be physically contacting the exhaust manifold, and these could be designed to transfer as much heat as possible. Aluminum with flutes that are parallel to the flow, and if EGR could be used, then that would use the "excess" heat instead of generating even more heat.
If the efficiency is high enough and enough of the heat is actually used by the engine, this would minimize the capacity of the cooling system, too.
Another major advantage of this design it seems to me is that is would require very little flywheel weight, since each 180 degree exhaust stroke is mostly offset by the 135 degree power stroke; leaving only the 45 degree "mini" intake stroke as a loss phase. So, bearings would have less load, as well.