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Since Homogenous Charge Combustion Ignition (HCCI) engines can be designed to operate at similar pressures to conventional spark ignition engine, it ought to be possible to make a wankel engine that uses HCCI.
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Do you propose to mitigate the effects of an inherently high friction, low effeciency engine by adding some technology that slightly improves combustion effeciency? |
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It would make a more effecient Wankel, but that's like converting your Hummer to LPG to save fuel. |
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you didn't invent HCCI, or the wankel, so there really is no invention here. |
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If one combines two well baked ideas in a way that hasn't been done before, it's a perfectly good halfbaked idea. Or possibly a perfectly bad halfbaked idea, I suppose, but if so, it wouldn't be because the components had been baked. |
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Anyway, one of the disadvantages of wankel engines, according to Wikipedia, is: /The trailing side of the rotary engine's combustion chamber develops a squeeze stream which pushes back the flamefront. With the conventional two-spark-plug or one-spark-plug system and homogenous mixture, this squeeze stream prevents the flame from propagating to the combustion chamber's trailing side in the mid and high engine speed ranges. This is why there can be more carbon monoxide and unburnt hydrocarbons in a Wankel's exhaust stream./ |
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If a Wankel engine were designed to use HCCI, this particular problem would cease to exist, since combustion would occur at multiple locations, spaced equally throughout the combustion chamber. |
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In addition, spark ignited wankel engine size (and speed) is limited, due to the same reason, but with HCCI, a wankel engine could be made (arbitrarily?) larger. |
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// make a wankel engine that uses HCCI.// |
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Dude, you gotta explain *how* or it's just a WIBNI. |
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Making a wankel engine use (low pressure) HCCI should be just like making a piston engine use HCCI -- instead of using the spark plug to produce combustion, recirculate exhaust gas to provide enough heat that compression causes combustion. |
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The reason wankel engines in the RX-7 are famous for going bang expensively and regularly is because there's a build up of carbon on the outside of the chamber, wearing down the tips of the rotor. You're proposing recirculating more exhaust round to the inlets, increacing the carbon content of the intake gas! |
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not to mention the fact that even few hard detonations can lead to cracked apex seals and any number of other mechanical failures. Also since the combustion chamber is naturally pretty cold (in the heat imparted to the charge) you are going to need a seriously marginal mixture to come anywhere near auto ignition and then the whole question of "why" rears its ugly head because as you just observed the rotary has a naturally uneven combustion due to the "quench wave". In no way is having multiple "hotspot" auto ignition points going to resolve this problem. Here we have an engine that is marginal in terms of reliability and wears out very quickly if thermally or mechanically abused and that already requires a complicated multi-stage spark ignition system to run well.... well you can see why the angels fear to tread, so to speak. |
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