I'm a programmer, not an engine guy. From the description in the article, they do one intake stroke, two pairs of compression-power strokes, followed by an exhaust stroke.
Also, it seems the initial compression-power strokes are done with the piston moving lower, ie both lower top dead center and bottom dead center, hence would have lower compression, and the second moving higher so with higher compression.
From my understanding of more fuel means less compression is tolerated before knocking[1], and vice versa.
So do I understand it correctly that their idea then to make the first power stroke rather rich with lower compression ratio to eliminate knock, and the second at a higher compression ratio to burn the remaining unburnt fuel? Or the other way around, ie lean with high compression first?
If so, it seems like an evolution of variable compression ratio engines[2].
edit: my morning-brain is having issues with thinking about how air-fuel ratio change in rich-burning vs lean-burning scenarios. So perhaps they aim for a good stoichiometric ratio and rely on the exhaust gasses to avoid knock when increasing compression the second time around?
[1]: https://en.wikipedia.org/wiki/Engine_knocking
[2]: https://en.wikipedia.org/wiki/Variable_compression_ratio
I always wonder about premises in cases like this. a pair of compression-power cycles is a nice way to question the usual. has anyone gone through all the features of a conventional engine and asked: what if there's an alternative?
for instance, what if we're just interested in range-extension? can we transform the motion created by combustion into electrical power in a clever way? cylinder-solenoid coils?
are poppet valves so great? suppose we have some other mechanism to create the motion (solenoids?) or rotating valves? something electromagnetic appeals because it gives complete control over timing (rather than a crankshaft).
rotary engines are appealing, for the same contrarian reasons. but they seem to either have practical problems (wankel) or don't seem to be making it to market (peanut-shaped rotors, etc).
if 6 cycles makes sense (presumably in combustion physics), does it make any sense to burn in one chamber, then move those products to another chamber for some further (potentially different) cycle?
would it help if you could ignite from more than a single place? multiple plugs sounds like a bit of a pain, but could you generate an annular spark? would you want to control the location-timing of the combustion front? does rotating-detonation have any meaning in this context?
are there ways to reconsider the materials engineering of engines? make them dramatically cheaper, lighter? one of the best EV arguments is simplicity, but how much of current IC engineering is based on assumptions that can be broken?
This article has brought out a lot people to comment who don't know anything about sports cars, but feel necessary to insist they do. It's bad enough that I had to login in to dispell this reoccurring canard:
"EVs are faster in a straight line! EVs have a flat/high torque curve!" -- big whoop.
1) 0-60 times are biased against ICEs as their torque curves _aren't_ flat and so the start of range is mostly when the engine is at a disadvantage. In an actual road situation the ICE is already at speed and therefore at or near the peak of their torque curve.
2) Actual roads have these things called "curves". Your bulky heavyweight EV handles like a brick on 3 wheels. And it doesn't have as responsive braking due that weight.
The number of the Porsche patent application:
20240301817
(which can be used on various sites, e.g. https://pat2pdf.org/ to retrieve the document)
Know nothing about automobile engineering but somehow this feels like WordPerfect releasing a fantastic version for DOS when Windows was already capturing all the market.
Btw they did that. Rest is history.
I like the old 6-stroke engines better:
- Dyer/Crower engine = 5th stroke compresses air only, then inject cold water into the overheated cylinder and has another power stroke on 6th (from the generated steam)
- Ilmor/Schmitz = the exhaust stroke from two normal 4-stroke cylinders power the down-stroke of a 3rd larger cylinder, alternatively, then evacuates the gas on 6th up-stroke. [1]
[1] https://www.youtube.com/watch?v=muq1xlF8Gu4
PS: For some reason, the Ilmor/Schmitz is call a 5-stroke engine.
Not to say that modern IC engines are any sort of "simple"...but there appear to be a lot more high-precision moving parts, under load, in their clever new crankshaft assembly. (Vs. traditional 4-cycle IC engines.)
Obviously, Porche's target market isn't likely to care about that.
But for possible down-market uses of this technology - are there any mechanical engineers in the house, to comment?
But isn't the chamber full of exhaust at the beginning of the second power stroke? What will burn?
> To do this, Porsche's patent shows a crankshaft spinning on a ring with two concentric circles—an annulus. ... this engine has two top and bottom dead centers.
Instead of doing this complicated crankshaft, I wonder if you could do this with opposed pistons. The difference between the two top dead centers (and bottom dead centers) is small, so the secondary piston wouldn't have to move far to create the same change in volume.
I can see some advantages and disadvantages. The crankshaft gets simpler, but you need to move the secondary piston somehow, presumably off the camshaft? Which sounds pretty rough on the timing chain. Also, it would have to go where the valves currently are. And another piston ring to wear out.
On the other hand, the crankshaft gets simpler, and it's a critical component since it's transmitting all the engine power. Also, with the opposing piston, you could use a cam to get greater control of exactly when the volume changes happen.
I'm sure one day we will look back and laugh about how we used to install actual mobile power plants in our cars. But as of today, they are still objectively better on many criteria.
Reading these articles is like when you used to read articles in 2005 about people "innovating" on OS/2.
The market has moved to electric (see China) and Porsche would be well served on investing there versus on OS/2 (nee ICE engines).
That is brilliant!
As soon as they release one with a coal fired steam engine, I'm onboard!
Nothing like last millenniums technology today...
Know nothing about automobile engineering but somehow this feels like Wordpress releasing a version for DOS when windows already captured most of the PC market.