Chen Engine part 2

[Chengine]

This second part of Chen engine is a 6 stroke engine. Two more strokes are introduced just before the combustion.
The benefits are better mixing of the air-fuel charge and more complete combustion. The fuel is totally vaporized by the 2 additional strokes. This clean burning is similar to natural gas burning, therefore cleaner. The difference in thermal efficiency between diesel and Otto will be minimized, as 6 stroke Chen engine will have close to diesel efficiency. The drawback is that power is reduced by 1/3.

This 6 stroke engine is best used as electricity generator, at full load and low speed to achieve the best thermal efficiency for internal combustion engine. Thus, best engine for hybrid cars, Maximum efficiency and minimal pollution


The patent application has been published on Feb, 8, 2018. It is US20180038275A1. Detailed description can be found there.

[Greg Locock]

Interesting idea to encourage mixing when everyone else(I exaggerate) is going for stratified charge

[J.A.W.]

& to paraphrase Sir Stanley Hooker, '6 strokes provide one power-stroke, plus 5 - to wear the engine out'.

Perhaps Mr Chen could join forces with fellow member here, & also self-proclaimed 'prophet'
- of advanced spoonbending, ah, sorry, - I mean 'advanced engines' -'Feliks', & amaze us all, yet!

[Cold Fussion]

Here we go again boys.

[Chengine]

When the fuel air mixture is uniform, the combustion is burned in very lean condition at 0.7 (fuel/air equivalence ratio), thus 100% burning and clean. Of course around the spark plug, there will be small region of fuel rich mixture by the final fuel injection just prior to spark ignition. (local stratified charge).

The mechanical loss and wear and tear is reduced by low and very low RPM operation. This high efficiency engine will operate sat very low rpm to attain 50% thermal efficiency. (matching diesel but very clean)

The Power of the engine could be increased by the increase in volume of combustion chambers. (the opposite of Turbo charging). The fuel efficiency will still be maintained.

With first part of Chen engine's efficiency improvement of 10% and double mixing improvement of 20%, this is about the maximum efficiency that can be achieved with gasoline internal combustion engine. .

[Chengine]

I just want to say that "6 stroke engine" and turbocharging or supercharging are not mutually exclusive. It would be nice to have a small powerful engine that is also fuel efficient and clean.
I just want to tell a story that when I was in Germany almost 30 years ago. I drove a carburated MB 4 cylinder 2.3 liter engine car doing over 220 Km/hr. I saw my tail pipe spitted out tremendous amount of carbon fragments. It did not have any catalytic converters.

[johnny comelately]

& to paraphrase Sir Stanley Hooker, '6 strokes provide one power-stroke, plus 5 - to wear the engine out'.

Perhaps Mr Chen could join forces with fellow member here, & also self-proclaimed 'prophet'
- of advanced spoonbending, ah, sorry, - I mean 'advanced engines' -'Feliks', & amaze us all, yet!

This practice of ad hominem is not constructive.
mr chen is simply exploring engineering paths, so a discussion of the pros and cons is best.

[J.A.W.]

& to paraphrase Sir Stanley Hooker, '6 strokes provide one power-stroke, plus 5 - to wear the engine out'.

Perhaps Mr Chen could join forces with fellow member here, & also self-proclaimed 'prophet'
- of advanced spoonbending, ah, sorry, - I mean 'advanced engines' -'Feliks', & amaze us all, yet!

This practice of ad hominem is not constructive.
mr chen is simply exploring engineering paths, so a discussion of the pros and cons is best.

"Ad hominem"?

I dont think so Johnny C-L, & my paraphrasing of Hooker's view - is surely apropos on a 'technical' basis.

& I'll add a Christopher Hitchens dictum here:

'What is asserted sans evidence, may be dismissed, accordingly'.

If Mr Chen can prove his ideas do not belong in the 'crackpot' category - ( via 'the pudding') ok, fine,
but frankly, if you review his prior claims - as posted on this forum - the probability aint high, IMO..

[Chengine]

The better efficiency of diesel chemical combustion converted to useful mechanical energy is due to its more consistent ignition and combustion of its fuel, despite the occasional black soots from its operation. It has close to 100% burning of its fuel.

The inefficiency of gasoline engine is due to its shot to shot variation of gasoline air mixture combustion. Both the peak pressure amplitude and pressure pulse timing varies 10% or more. Thus the conversion to mechanical power is sub optimum and highly inconsistent. The reason is that the charge composition is very inhomogeneous. It even includes large patches of liquid gasoline, especially when the RPM is high and liquid fuel has yet to vaporize before ignition

The out of the box solution is "double mixing" of fuel air mixture. From literature, only 80% of the fuel is burned in combustion chamber, with slightly rich mixture for drivability reason. (If not, the engine is rough). With double mixing we can assume that the remaining 20% will have another 80% efficiency, and we have 96% total combustion. Thus, we will not have rough engine, but still have lean mixture and consistent ignition and same conversion as diesel.

The greatest benefit is that at low RPM, the fuel goes through 1 1/2 compression heat cycle. The fuel should be completely vaporized and homogeneous and we can treat it as if it is Natural gas combustion and thus clean. If this is the case, then we have an engine as clean as natural gas powered engine.

There is a world wide pressure to eliminate internal combustion engine for various reasons, pollution as being foremost. This double mixing, six stroke engine might keep it as the engine for future hybrid vehicles.

[Greg Locock]

" From literature, only 80% of the fuel is burned in combustion chamber,"

At full power that may be the case, and it is deliberate to cool the valves and cat. Away from full power that is not the case, almost all the fuel is burnt. I haven't got numbers to hand but >99% springs to mind.

[Chengine]

The data is called Variation of engine combustion efficiency with fuel/air equivalence ratio, on Page 82 of Heywood's Internal combustion engine fundamentals. The 80% corresponds to equivalence ratio of 1.1. As the ratio gets to close to 1.0, the efficiency is close to 90%. And the case for diesel is 95-98% at 0.8 equivalence ratio.

As we are all aware the excess fuel must be burned before it exits the exhaust system, or it will fail HC smog test.
Engine makers introduce Oxygen at the outlet of the exhaust port to burn the excess fuel and partially burned carbon particles. Mercedes Benz introduced particle filter for their new cars. Obviously, they generate PM 2.5 particles

Also from the same book, literature says with uniform fuel/air mixture, it'll burn completely, just like diesel down to 0.7 equivalence ratio..

[Tommy Cookers]

fuel in the exhaust equivalent to 4% of stoichiometric seemed to be stated for 3 way catalyst action (4% or cycling 0%-4% ?)
to eliminate oxygen which otherwise would prevent catalytic reduction (maybe these days full-time reduction is not needed ?)

so (I would have guessed) undercombustion in the chamber by much more than 4% would overheat the oxidation catalyst ?
which couldn't be cooled by extra fuel ?

[Chengine]

The entire point of "6 stroke" engine is to avoid use of any cat converter.

I am very sorry to say that I am not a fan of any converter. First, the three converter needs 425 C(800F) to work.
If placed too close to exhaust manifold it'll cause vapor lock. Thus, it must be placed relatively far from the engine. If it can heat up rapidly, it also means it can cool down rapidly once engine stopped. If you have a post delivery truck, it'll never have one ounce of conversion all day. Worse, when starting, you have very rich mixture for ease of cold engine start, and all that excess fuel go straight to environment. I have also learned from my German friend never to warm up car in any case. Just drive once started for minimum pollution.

To me, so called cat solution is at best a partial solution to air pollution. I would rather not spend any discussion time on that. My old car could never pass smog test even after a long drive and parked for 30 minutes in summer. Of course, the operator assured me it'll always pass the second time. I really do not know what to say.

The 6 stroke engine will not be built on top of anti-pollution devices. If it does not have ultimate efficiency, it must be as clean as natural gas vehicle, or it has no merit for existence.

[Cold Fussion]

So your 6 stroke engine does not produce CO or NOx in fuel combustion?

[Chengine]

Since the engine should run very lean and in very homogeneous charge, I expect that HC and CO will be very low.
However NOx will be the only pollutant left, I assume. Instead of Catalytic converter, I'll try to find other means of eliminating this pollutant. Worse technique is MB method for treating NOx, Urea spray.

Thus, at least there is a anti-pollution solution that has 100% coverage. Since particulates now appears to be a problem, I hope the 100% vaporized HC will burn very close to natural gas and creates no particulates. We'll see.

I would also like to make a point on synchronized combustion. The 6 stroke engine will have such a consistent combustion, both is amplitude, shape and timing, the torque generated is larger than disorganized combustions with 10% variation in every category of existing 4 stroke engine. The analogy is team rowing. Every member of the team must by synchronized in order to compete and win races. Needless to say, diesel engine is synchronous in combustion.