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The CITS 2 stroke engine


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#1 cheapracer

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Posted 03 April 2012 - 19:34

Another thread reminded me of another "2 stroke with 4 stroke lubrication" engine (one of many). I have had info on for some time and I just checked that's it's now clear to post some details based on a patent having been approved.

It's a fairly simple design that the inventor believes solves some problems of the 2 stroke. It uses a crosshead type piston enabling the bottom end (crankshaft and rods etc) to be lubricated as a 4 stroke engine typically is with the obvious advantages of keeping oil away from the combustion process as well as using cheap slipper bearings rather than roller cranks. The crosshead piston design allows a separate chamber to be incorporated as part of the crankcase using the lower side of the piston to act as a pump (supercharger), induction being via a one way valve (typically a simple reed valve is nominated). On the downward stroke, reed valve closes and charge is delived to combustion chamber via transfer ports as can be seen.

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The inventor states that this allows pure air-petrol to be used without the usual oil mixed in that causes the pollution of a normal 2 stroke engine. He has mentioned how he lubricates the rings but was confidential and is not mentioned in the patent that I can see so I will not mention it.

One of his innovations to save on pumping losses and costs in a twin cylinder version is to allow the fore'mentioned supercharging chambers to be connected by a port (after the reed valves) containing a throttle valve that can be manually opened and closed to operate as the throttle. The air in these chambers is merely transfered from supercharge chamber to supercharge chamber rather than a vacuum being created at part throttle therefore saving on pumping losses. No normal air/fuel intake throttle valve is required as the throttle valve in this transfer port is opened for low revs and gradually closed to encourage air to come past the reed valves increasing induction - the "Pivot Petal" drawn below...


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Not just a drawing either, had a 100cc Yamaha based Kart engine running in this configuration.


What do I think? - as I told him ..

Being an older guy who has adoration for 2 stroke racing engines of the 60's, he falsely believes that crankcase compression is where it's at, he has about 4:1 currently - well this is 50 years later and it's well established that less than 1:5 is ideal to prevent the charge being blown too far up the exhaust port so a pressure wave (formed by the design of a 2 stroke exhaust) can return it effectively. Of course there will also be pumping losses but the other issue is heat, compress air to 4:1 and the heat has a dramatic increase, not good for anything and I believe that Nox will increase due to that(?).

The throttle'less system, while certainly has pumping loss improvement merits, also is a heat riser in an age where engine designers are trying to keep the combustion cooler to fight Nox.

He didn't much like me after that, seems to be a common trait with inventors :lol:

Edited by cheapracer, 03 April 2012 - 19:41.


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#2 Greg Locock

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Posted 03 April 2012 - 22:17

Reminds me a little of the Bourke Engine, Scotch Yoke 2 stroke with crankcase supercharging. The current promoter of that device is fairly bitey as well. As I've pointed out to him BSFC and powercurve tests on an independent dyno would do a great deal to assuage the barracking. One guy who did that was the developer of the Revetec engine, http://www.revetec.com/ - good on him.

#3 cheapracer

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Posted 04 April 2012 - 05:03

And a similar more traditional 2 stroke but with isolated lubrication, the SPEC square piston engine - probably has a use in chainsaws, mowers, whipper snippers etc....



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One guy who did that was the developer of the Revetec engine, http://www.revetec.com/ - good on him.


That would be this one ....

News Archive - 1st March 2008 - X4v2 engine completes Independent testing at Orbital Australia - The Directors are pleased to announce that the X4v2 petrol engine achieved a repeatable Brake Specific Fuel Consumption (BSFC) figure of 212g/kW-h (38.6% engine efficiency) with a best figure of 207g/kW-h (39.5%) at our requested target test of 2,000rpm with a BMEP load of 450kpa (approximately 75% load) and an air/fuel ratio of 15.2:1 using 98 RON petrol and a 10:1 compression ratio. We also achieved a BSFC figure under the same rev and load conditions using an air/fuel ratio of 14.5:1 of 238g/kW-h (34.4%)


And apparently they are all off to India to develop ....

Revetec personnel are relocating to Turkey for a development program with a large Indian manufacturer. After Six months, our personnel (including Directors Mr B Howell-Smith and Mr P Kelly) is relocating to India to expand the development program for a range of diesel engines.

It's a shame current Western Governments don't seem to take much of an interest.

#4 manolis

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Posted 04 April 2012 - 06:39

About the CITS 2 stroke engine:

This arrangement:

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from http://www.pattakon....pattakonPPE.htm , has some more advantages (full balance – as Wankel rotary, very short if single cylinder, no thrust loads etc). The single-sided crankshaft is not a must.
The 2-stroke version of this

Posted Image

is also interesting (full balance – as Wankel rotary - , very compact, no thrust loads).

Taking the thrust loads away from the ports is a good thing and reduces the oil consumption, as in the CITS VR engine.
This is what is doing Achates with their Opposed Piston engine with the side crankshafts.
This is what is doing the PatOP engine:

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at http://www.pattakon....ttakonPatOP.htm

However with ports on the cylinder liner, and rings passing over the ports, and lube to prevent the metal contact of the rings with the cylinder liner, the lubrication is not “true 4-stroke”, it is “like 4-stroke” at most, because the lube can still find the way to escape and to be burned or lost.

A good example: the conventional cross-head 2-stroke giant marine engines wherein the piston head is completely rid of thrust loads, and completely isolated from the crankcase. Yet a lot of lubricant is necessary to protect from scuffing: the cost of the lubricant burned is about 4% of the cost of the heavy fuel oil.


For the REVETEC engine:

A more simple and compact version of the Revetec engine is presented at

http://www.pattakon....ttakonGreco.htm

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This:

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is a 3-in line even-firing engine, perfectly balanced (as the Wankel rotary and the V-12, and better than the best V-8).
The problem with the replacement of the conventional crankshaft by cam-drive-mechanisms is the extreme local pressure on the “line contact” wherein the roller abuts on the cam surface.

The same problem (long term reliably) killed the Bourke engine :

Posted Image

which also had good fuel efficiency for the short periods between overhauls.

Thanks
Manolis Pattakos

#5 cheapracer

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Posted 04 April 2012 - 07:18

Awesome, we can make this thread the "Ultimate list of engines that will never see production". (Although the Revtec just might get there).

I'll add the most famous current one, the Scuderia which is also a 2 stroke with conventional 4 stroke lubrication. Interesting how it takes over 15 years and some $50 million dollars of investment to build one or two prototypes and some fancy videos of what is a simple common parts based engine ...

http://en.wikipedia..../Scuderi_Engine

http://www.scuderiengine.com/


... when this guy and his "Tour Engine" can do the same thing with 2 lawnmower engines in his backyard for a few thousand dollars ...



http://www.tourengin.../prototype.html





#6 manolis

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Posted 04 April 2012 - 09:18

On 2008 we met Scuderi at Engine Expo Stuttgart Germany.
Scuderi came to pattakon booth to see how our Desmodromic DVVA system operates: his engine needs special control over the valves; besides the typical valves he has also “transfer” valves which need widely variable control and operate at double frequency than the normal valves.

On 2009 we met again at Stuttgart: Scuderi's booth was at the one side of the “Open Forum” (3 meter from the girl shown)

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while pattakon’s was at exactly the opposite side ( http://www.pattakon....attakonEXPO.htm )

He was exhibiting his demonstration prototype engine, this time. The finishing / quality of his prototype was remarkable, however it was massive for its capacity (counterbalancing shafts, double teethed synchronizing belt etc).

Scuderi’s engine is not a 2-stroke engine, nor a through-scavenged engine.

According Scuderi:
“The Scuderi Engine divides the four strokes of a combustion cycle between two paired cylinders—the left cylinder functions as an air compressor, handling intake and compression, while the right cylinder handles combustion and exhaust. Key to Scuderi’s split-cycle design is that it compresses the air in a separate cylinder before it fires.”

When un-supercharged, the air suctioned into the compressor cylinder is all the air that is going to be burned – by the set of the two paired cylinders - in a complete revolution of the crankshaft. That is if the compressor cylinder is 500cc and the combustion cylinder is 500cc (1000cc total capacity), the Scuderi engine burns, per crank rotation 500cc of air, like the four stroke of same capacity. Differently: the Scuderi is a 4-stroke wherein half cylinder are dedicated to the intake and the compression, while the rest half are dedicated to combustion, expansion and exhaust.

Unless I am wrong, the other engine (Tour Engine) is a two crankshaft version of the Scuderi.


The next year (2010) pattakon was not at the Engine Expo because our presentation for an improved MultiAir system (the PatAir) was not approved (in the hind side: it was incompatible with their “best new engine of the year fiesta” for the MultiAir of Fiat / Schaeffler ).

And here is an e-mail still waiting an answer from Schaeffler and FIAT:

“Schaeffler-INA (of Germany), and FIAT (of Italy), both are bordering Austria, the country of Ludwig Boltzmann, the father of the Statistical Mechanics.

The Scientists and Engineers of FIAT and Schaeffler knew (or should, according Boltzmann) that the elimination of the throttle valve brings about a Biiig difference:

The throttle valve was a killer, it kills the pressure downstream (upstream the valves)
The gas upstream the valves was dead as the valve opened, an almost zero pressure difference across the valve port drew a slow stream of thinner air/gas.

Now, with the elimination of the throttle valve, in the MultiAir/UniAir/TwinAir engines of FIAT-Schaeffler there is not pressure killer, any more:
The pressure difference between the outside of the valve (plenum) and inside the valve (cylinder) is huge is biiiig is strong:
Now, the fresh gas rushes/storms into the cylinder at SONIC speeds (or near), generating local Hurricanes and Tornados and Twisters: The local Reynolds numbers are huge.

One result is the Biiig increase of the heat transfer between the gas and the walls (piston-crown and cylinder-head and liner)

This heat exchange takes place at the worst timing and towards the worst direction:
The fresh gas get hot, hotter than FIAT thinks or used to think before the publication of the patents of the PatAir:

http://www.pattakon....ttakonHydro.htm

As a result, all the temperatures throughout the thermodynamic cycle increase; the higher the temperatures the worse the fuel efficiency, or not?

We have seen it into our Honda and the Renault Prototypes, when the MultiAir was rather sketch than drawing:

http://www.pattakon....takonRoller.htm

http://www.pattakon....pattakonRod.htm

FIAT and Schaeffler didn’t listen, They knew it all.
“Base your knowledge on facts and analysis and not on what everybody know: when everybody know that something is so, nobody knows nothing”
is the best advice Andy Grove of Intel ever get.

Are they, the shareholders of FIAT and the shareholders of the Schaeffler-INA who pay the price now?

Did Stephen Hawking put it like this?
“Nobody can argue with Mathematics”

Thanks
Manolis Pattakos

Edited by manolis, 05 April 2012 - 02:29.


#7 Greg Locock

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Posted 04 April 2012 - 09:37

I vaguely remember two things about Scuderi. (1) The twingle engine from the 1950s (2) lawyers. I'm glad you survived unscathed.

#8 cheapracer

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Posted 04 April 2012 - 10:42

I vaguely remember two things about Scuderi. (1) The twingle engine from the 1950s (2) lawyers. I'm glad you survived unscathed.


I don't think it's changed, lawyer heavy company it is so I will decline to publicly call them rip off **** or mention it's just a glorified crappy, supercharged 2 stroke. they make one advancement per year to keep their investors happy and excited - this year it's "The Miller Cycle" being added.

Difference with the 1950's Puch 250 Twingle is they sold plenty of them that were good, cheap and reliable transport for thousands.


#9 MatsNorway

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Posted 04 April 2012 - 16:21

manolis i like your ideas but they seems too complex. Complex does not automatically mean bad as jet engines surely must qualify as complex machinery. At least more than most piston engines.

http://www.pw.utc.co...utaway_high.jpg

Revtec.
I like that Piston to crank/cam idea.

But surely you could make that work with a round piston? And is there no roller/glide bearing on that crank?

I guess its time for me to trow out one of my own crazy ideas that i find interesting but doesn`t really believe in.

Edited by MatsNorway, 04 April 2012 - 16:24.


#10 cheapracer

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Posted 04 April 2012 - 16:34

Revtec.
I like that Piston to crank/cam idea.

But surely you could make that work with a round piston?


Revtec pistons are round, what makes you think they are not?


#11 MatsNorway

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Posted 04 April 2012 - 16:46

Meant the SPEC square piston engine. made by some guy from Revtec.

#12 manolis

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Posted 04 April 2012 - 19:03

MatsNorway,

And when the added complexity is justified by the advantages?

The core of most pattakon projects is simple.

Take the HyDesmo system, for instance, at http://www.pattakon....akonHyDesmo.htm which seems complicated at first look.

Posted ImagePosted ImagePosted Image

However the heart idea is simple: to use the “opening ramp” of a camlobe to open positively AND to close positively the valve (i.e. desmodromically, without valve springs); optionally to modify the valve lift profile by the rotation of an “oil-piston” (like the piston of the old jerk pumps).
The rest are details.

As a whole, is the HyDesmo project complex or simple?
If another simpler / cheaper valve train system can do what the HyDesmo, then the HyDesmo project must be phased out.


Take the variable compression ratio (VCR) Head-Block version at http://www.pattakon....pattakonVCR.htm .

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Is it complicated?
If you compare it to a conventional engine (without VCR) of course it is.
But if you compare it to the similar project of Toyota (they put two eccentric shafts at the two sides of the block, with a gearing synchronizing them):

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you will be surprised how much simpler the pattakon Head-Block VCR is.
Fewer parts, direct passing of the combustion forces without creating bending loads, lighter and at the same time more robust and more compact engine, quieter engine, cheaper engine etc, etc.
If you can see just one point wherein Toyota's VCR is better (more functional) than pattakon's VCR, please let me know.


Another characteristic case is the PatAir system (at http://www.pattakon....ttakonHydro.htm ) which is also "too complex".
If you compare its complexity to the complexity of the state-of-the-art MultiAir of Fiat / Shaeffler-INA, they are identical.
But if you compare its functionality to that of MultiAir, the PatAir provides all the possible modes of the MultiAir and infinite additional modes of operation (OutGoing Air Control / unlimited Miller cycle, which seems to be the future):

Posted Image


Complexity is relative.

Thanks
Manolis Pattakos

Edited by manolis, 05 April 2012 - 03:19.


#13 cheapracer

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Posted 05 April 2012 - 03:22

As a whole, is the HyDesmo project complex or simple?


There's a "HyDesmo" project?

Ok, Hi Desmo! :wave:


#14 manolis

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Posted 05 April 2012 - 04:17

There's a "HyDesmo" project?

Ok, Hi Desmo! :wave:


HyDesmo comes from Hydraulic Desmodromic.
A version of the HyDesmo is the modification of the MultiAir system to Desmodromic:

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in order to get rid of the valve springs and their problems as explained at http://www.pattakon....akonHyDesmo.htm

In case you have thought about the HyDesmo project first, as you did with the one-way valves of the PatMar, please let me know to withdraw the patent.

Thanks
Manolis Pattakos



#15 gruntguru

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Posted 05 April 2012 - 04:29

Very elegant.
How do you limit the acceleration when the valve is approaching full lift and you suddenly switch from forced opening to forced closing at a time when the pump plunger is close to maximum speed?

#16 cheapracer

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Posted 05 April 2012 - 05:12

Very elegant.


Indeed, fantastic!

Manny, could you tell us more about real world applications of your products and how the manufactureres that are using them find them in real world service please?


#17 manolis

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Posted 05 April 2012 - 05:49

Gruntguru,

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The auxiliary piston 21 is slidably fitted to, and seals, one side of the closing oil chamber 5; together with its supporting spring 22, it serves as an oil pressure surge compensation means: during the pressure surging, the piston 21 moves slightly outwards of the closing oil chamber 5 dumping the pressure surge; when the pressure drops, the piston 21 moves, by the supporting spring 22, slightly inwards the closing oil chamber 5 to compensate any oil leakage and to keep, this way, the valve firmly closed until the next valve opening.

Besides, for as long as the valve is away from its valve seat, the smoothness of the transition from opening to closing is not important (provided the loads involved are into the acceptable limits). It is also the inevitable oil leakage around the oil piston, around the valve stem piston etc which acts as a damper.

Thanks
Manolis Pattakos




#18 gruntguru

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Posted 05 April 2012 - 06:01

Thanks Manny. So putting it simply - there's a relief valve limiting the peak pressure?

#19 manolis

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Posted 05 April 2012 - 06:41

Indeed, fantastic!

Manny, could you tell us more about real world applications of your products and how the manufactureres that are using them find them in real world service please?


This question is already answered at the PatMar thread (it is the thread wherein you "first" invented the "high tech idea" of using one-way valves in a 2-stroke engine).

And instead of asking me, would you be kind enough to ask Fiat and Schaeffler-INA, or your nearest Fiat dealer, to explain why the PatAir (which is ready for production, or it is not?) is not better than their MultiAir? (Or to answer my letter above?)


Unless I am wrong, a few minutes ago you deleted a comment about "thread's ownership", "about Felix" etc.
I think that in an open Technical Forum the strictly technical arguments and objections is what counts.
So let's get back to strictly technical:

Since you don't like the HyDesmo system (which is a true complex project), you can compare Toyota's VCR shown above with Pattakon's VCR:

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and answer the question: "Can you see just one point wherein Toyota's VCR is better (more functional) than pattakon's VCR?".

Thanks
Manolis Pattakos







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#20 cheapracer

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Posted 05 April 2012 - 07:54

And instead of asking me, would you be kind enough to ask Fiat and Schaeffler-INA,


No I'm asking you, are any of your products, not just the Patair, currently in pre or actual production by any manufacturer?



(it is the thread wherein you "first" invented the "high tech idea" of using one-way valves in a 2-stroke engine).


The thread is there for anyone to read. Yamaha are the inventors the (low tech) reed as we know it applicable to 2 strokes and I have provably demonstrated that millions of 2 strokes use them and able to quote myself here many times prior to any recent threads.

You want an example, of course you do, post 4
http://forums.autosp...y poppet valves?

And here, in post 2, I demonstrate other uses for reed valves on engines other than induction
http://forums.autosp...;hl=reed valves

Are we clear and finished on that subject now?

Unless I am wrong, a few minutes ago you deleted a comment about "thread's ownership", "about Felix" etc.
I think that in an open Technical Forum the strictly technical arguments and objections is what counts.
So let's get back to strictly technical:


I did indeed, I wrote (approx) " I suggest you start a Pattakon thread specific to your wares as Felix, myself and others have done rather than flooding other threads". I then realised that it wasn't my place to suggest it so I have suggested it to the Moderators as per forum rules.

Your flooding, spamming* and thread highjacking* (*against forum rules) here is actually off topic, please review the thread title above.

Applicable Autosport Forum rules;

*Trolling, thread hijacks, flame baits etc . These are not welcome. The mods don't like them and, from your complaints, it is obvious you don't like them either.

* Advertisements for-- or criticism of -- other websites. Two words for you: not here.

#21 cheapracer

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Posted 05 April 2012 - 08:32

Since you don't like the HyDesmo system (which is a true complex project), you can compare Toyota's VCR shown above with Pattakon's VCR:


and answer the question: "Can you see just one point wherein Toyota's VCR is better (more functional) than pattakon's VCR?".


Err, I didn't say anything about the Hydesmo other than a bit of humour based on what it sounds like.

But ok, if you're asking me then both systems are overly complicated, overly complex and no manufacturer would poke them with a stick. They will never see mass production.

Doing animations is barely related to what it takes to actually have someone put an idea into production. New ideas need to have foundations in cost, simplicity, ease of production (including production adaptability), end value, saleability, profitability - a wide range of considerations as a whole in what is a very, very conservative industry and IMO none of your ideas that I've seen cover all those bases.

Your constant bitching and moaning about FIAT not dropping everything immediately and throwing millions at you for your "obviously better" Patair invention, is indicative to me of your navety of the industry as a whole.

Here's a serious tip for you; Give up the automotive industry, take your obvious lateral thinking and go design medical and disability equipment where you will be more appreciated, accepted and make money.



#22 manolis

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Posted 05 April 2012 - 09:28

Thanks Manny. So putting it simply - there's a relief valve limiting the peak pressure?


Gruntguru,

It is a little bit different than a "conventional relief valve".
It actually adds the necessary elesticity to the hydraulic system, without - necessarily - allowing a quantity of oil to escapy from the chamber.

Thanks
Manolis Pattakos

#23 manolis

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Posted 05 April 2012 - 10:46

No I'm asking you, are any of your products, not just the Patair, currently in pre or actual production by any manufacturer?

As I wrote, your question is already and fully answered at the PatMar thread.

Of course you can refuse to comment on a project not being in pre or actual production. It is your right.
As I know, neither Revetec's engine is in pre or actual production, nor Scuderi's engine.
In case they decide to post their projects here, are you going to refuse?

Cheapracer: "We can make this thread the "Ultimate list of engines that will never see production". (Although the Revtec just might get there)."
Why? You see something secret in the Revetec architecture, that the rest cannot?

Cheapracer: "But ok, if you're asking me then both systems are overly complicated, overly complex and no manufacturer would poke them with a stick. They will never see mass production."
Again, why?
Are these your best technical arguments?
Here is a cut-view of the MultiAir (voted as the best new engine of the year 2011, and as the - by far - best engine of the year 2012):

Posted Image

Does it seems to you "neither complicated, nor overly complex"? Or it is not in mass production?


The rest members can decide by themselves what they like to comment on, and what not. Leave them to decide by themselves.

By the way:
The Wankel rotary was, for several decades, out of any kind of production (pre, actual or mass). I would comment on it, as most mechanics and engineers did at that period.
The Wankel rotary finally got into production. Billions of dollars were invested (and lost) by the automakers. Everything was based on the original idea of Felix Wankel. At that time most of the comments were meaningless.
The Wankel rotary is now phased out. Neither in pre, nor in actual production. I still comment on it, calculate things about it, learn things from it.
Without the money of the share holders of Mazda, would be any rotary engines?

Without the money of the shareholders of Ducati, would be a desmodromic at MotoGP or a panigale?
Compare Ducati's Desmo to http://www.pattakon....ttakonDesmo.htm , and if you know a dealer of Ducati ask him.

Thanks
Manolis Pattakos

#24 rory57

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Posted 05 April 2012 - 11:02

The inventor states that this allows pure air-petrol to be used without the usual oil mixed in that causes the pollution of a normal 2 stroke engine.


The pollution from a "normal" two stroke engine is not due to the oil mixed with the fuel as is so often stated, it is due to unburned fuel+oil in the exhaust.
From time to time I run out of lawnmower fuel and use the chainsaw fuel in the lawnmower. The four stroke Honda lawnmower produces no smoke at all when using this same 30:1 fuel/oil mix. Neither did my old BMW when I used the chainsaw juice in that after running out. The chainsaw produces the vile blue exhaust common to carburretted two strokes.
The exhausting of unburned fuel is the main reason the crankcase scavenged two stroke is so thirsty. Not a problem for Diesels as no fuel is injected until safely after the exhaust ports are closed and scavenging is done with clean air only. Hence the (limited) success of two stroke Diesels of various configurations.

#25 MatsNorway

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Posted 05 April 2012 - 11:58

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First i must say that its not a bad idea.

You have:

5 cams
5 joints

Toyota got

12 blocks for the guides of the cam.

and 8 blocks boltet on to the cyl block where the offset cam goes. as well as a frame just to steer and move the cyl block.

Complex indeed.

However i think your mechanism needs to be moved up/away and strengthened alot because its not likely by coinsidence that the toyota got 12 beefy guides and 8 big blocks where the cam goes. You also need the space for spark plugs etc.


SAAB had a variable compression design.

http://t1.gstatic.co...p8Qu0rYxgRWip8P

Posted Image

GM(?) refused to sell those patents as a part of SAAB when they went down. Thats the one you have to beat.



#26 gruntguru

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Posted 05 April 2012 - 12:14

Gruntguru,

It is a little bit different than a "conventional relief valve".
It actually adds the necessary elesticity to the hydraulic system, without - necessarily - allowing a quantity of oil to escapy from the chamber.

Whoops, sorry I rushed in a bit quickly there without looking closely enough at your diagram. It's more like an accumulator than a relief valve?

#27 gruntguru

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Posted 05 April 2012 - 14:20

As I wrote, your question is already and fully answered at the PatMar thread.

He can't be seen to go there.

#28 manolis

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Posted 05 April 2012 - 14:40

MatsNorway,

In your comparison you count the eccentric shaft of the pattakon Head-Block VCR as 5 cams.
However it is a single piece shaft (it is like a camshaft having cylindrical camlobes, all at the same angle).
This makes the shaft both: strong and lightweight.

In Toyota’s VCR case, the two eccentric shafts are necessarily multi-piece shafts. If you look more carefully at the drawing, each of the two eccentric shafts of Toyota comprises a thin central shaft (53a), a set of stationary pins (53b) and a set of movable pins (53c). The center to center distance of the (53b) and (53c) sets varies when the compression ratio changes.

Here is the core idea of this patent (from the widows exe 3d-animation at http://www.pattakon.com/vcr/VCR.exe ) :

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Quote from pattakon web site:
"The crankcase has projections comprising pillars and bridges. The pillars enter, through proper openings, into the cylinder head. The bridges couple the free ends of the pillars to strengthen the structure and to provide supports to a control shaft.
The control shaft is pivotally mounted on the cylinder head above the combustion chambers and, by 'small connecting rods', it is supported on the bridges.
The narrowing between neighboring cylinders, typical in conventional cylinder blocks, is an available free area for the pillars to pass and an available free surface for sliders.
The pillars connect, as directly as desirable, the tightening screws of the crankshaft bearing caps to the tightening screws of the bridges.
The gas pressure force on the piston causes a heavy 'column load' on the connecting rod. The equal and opposite gas pressure force on the cylinder head passes initially to the control shaft, then it is shared between the two neighboring 'small connecting rods' causing pure 'tension loading', then it is shared among the four neighboring pillars causing pure 'tension loading' too.
The thrust force from the pistons onto the cylinder wall, several times weaker than the gas pressure force onto the piston, passes to the crankcase through sliders at the lower, well supported, side of the pillars"



The Head-Block VCR of pattakon is quite different than SAAB's and Toyota's.
It passes directly, by means of the pillars, the strong combustion forces from the cylinder head to the crankshaft bearing caps, leaving the cylinder block unloaded.
In case the cylinder head and the block are made as a single piece, the engine becomes better, cheaper and more reliable.

The other two VCRs leave the strong combustion loads to travel from the center of the cylinders to the two sides of the engine, and then they pass again those strong loads from the two sides of the engine to the crankshaft. The resulting bending loads are extreme and the engine casing and block need a lot of strengthening.

After the basic patent, SAAB filed a number of additional patents for the compensation of the additional noise and vibrations, for strengthening the cylinder block and of the crankcase etc. That is, their solution generated new, more difficult problems.

So, the pattakon Head-Block VCR needs not be strengthent like Toyota's and SAAB's because it hadles the heavy loads the right way.

From another viewpoint:
Keep a nail on a hard surface, take a hammer and hit the nail.
For as long as the nail is straight (like the pillars) it passes tones of force to the hard surface without a problem.
Now take a bend nail (like the path-way of the combustion loads from the cylinder head to the crankshaft of Saab’s and Toyota’s VCRs) and do the same.
If you want to pass the same force to the hard surface, the bend nail must be several times stronger.



Gruntguru,

Yes, it is like a small accumulator for the pressure surges.

Thanks
Manolis Pattakos

Edited by manolis, 05 April 2012 - 15:00.


#29 manolis

manolis
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Posted 10 April 2012 - 05:29

The pollution from a "normal" two stroke engine is not due to the oil mixed with the fuel as is so often stated, it is due to unburned fuel+oil in the exhaust.
From time to time I run out of lawnmower fuel and use the chainsaw fuel in the lawnmower. The four stroke Honda lawnmower produces no smoke at all when using this same 30:1 fuel/oil mix. Neither did my old BMW when I used the chainsaw juice in that after running out. The chainsaw produces the vile blue exhaust common to carburretted two strokes.
The exhausting of unburned fuel is the main reason the crankcase scavenged two stroke is so thirsty. Not a problem for Diesels as no fuel is injected until safely after the exhaust ports are closed and scavenging is done with clean air only. Hence the (limited) success of two stroke Diesels of various configurations.


Quote from:
“Effects of Lubrication System Parameters on Diesel Particulate Emission Characteristics”
R. B. Laurence and Victor W. Wong and Alan J. Brown
Sloan Automotive Laboratory
Massachusetts Institute of Technology

. . .
Diesel particulates are commonly defined as any exhaust material, except water, that can be collected on a filter in diluted exhaust at a temperature below 53 oC, following protocols established by the US Environmental Protection Agency (EPA). Particulates consist of aggregates of small particles. Predominantly, each particle comprises a carbon core with a complex collection of hydrocarbons and inorganic compounds which have condensed or adsorbed on the surface. It is the collection of adsorbed compounds, particularly the carcinogenic polynucleic aromatic hydrocarbons (PAH), which may create the most significant health risks. Using traditional analysis, these compounds can be extracted using organic solvents such as dichloromethane, and the soluble organic fraction (SOF), i.e. the soluble organic percentage of the total particulate mass, can thus be determined. Clearly, it is desirable to reduce not only the total particulate rate, but the harmful carcinogenic compounds found in the SOF.
. . .
Percentage contribution of lubricant to the total particulate matter varies predominantly by engine condition, reaching as high as 70% of total particulates and 90% of the soluble organic fraction in the particulates under some operating conditions, viz, light to medium loads. The problem is less severe at high loads, as most of the consumed oil is oxidized due to the higher temperatures. For engines of older vintage, the oil contribution to particulates alone far exceeds the current standard for the total particulate matter for new engines. The lubricant contribution will become increasingly important as the total particulate emission level continues to be reduced in the future.
. . .
TEST MATRIX:
Three variables were used for this study.
Each test condition was run five times for repeatability.
Two production oils of differing viscosity (10W-30 & 15W-40) with the standard manufacturer's ring configuration were used for the first comparison.
Then, using the 15W-40 oil, the top ring gap was enlarged for a second comparison.
For each of these three lubricant parameter conditions, the engine was tested at three loads.
45 total tests were conducted for final analysis.
. . .
CONCLUSIONS
The results indicate that lubricant viscosity and the gap size of the top piston-ring do have a significant effect on diesel particulate emissions. Various specific conclusions can be drawn from the results and are summarized as follows:
1. Total particulate emission rate increases with decreasing viscosity. This effect is due most likely due to two mechanisms. First, the decreased viscosity leaves a thicker film on the liner during and after the expansion stroke, allowing more oil to participate in the combustion event. Second, decreased viscosity allows a larger puddle of oil to accumulate and subsequently pass through the ring gap when the cylinder pressure falls below the inter-ring pressure, again allowing more oil into the combustion chamber.
2. Total particulate emission rate increases with an increased ring gap width. This result is also derived from the ring-gap reverse flow theory of oil consumption, whereby oil passes through the ring gap and is consumed when the cylinder pressure falls below the inter-ring pressure. The results of this study serve to further confirm the presence of this oil transport mechanism and the significant effect it has on oil consumption and emissions.
3. At hotter conditions, the extra oil present in the combustion chamber due to changes in a lubricant parameter is mostly partially oxidized and emitted as carbonaceous material. At cooler conditions, most of this extra oil remains in some hydrocarbon form and is eventually adsorbed on the particulate, thereby contributing to the oil derived soluble organic fraction of the particulates.
4. Changes in lubricant parameters affect not only the oil-derived emissions, but fuel-derived emissions as well. Through the process of fuel absorption and desorption, increased oil on the liner prevents additional fuel from participating in the combustion event, thereby increasing the fuel derived portion of the soluble organic fraction of the particulates.
5. Engine load has an effect on particulate emission rate and composition. At higher loads, the soluble organic fraction is reduced. The greatest total particulate rate is at low load, while the medium load condition created the lowest rate. This agrees with traditional findings.
6. Simultaneous measurements of the oil distribution in the piston ring-pack, using methods such as the laser-induced-fluorescence, and real-time oil consumption as well as particulate measurements will further elucidate the mechanisms by which lubricant contributes to the total particulate emissions and the opportunities for improvement.


You can find the complete pdf article in the Internet, or at:
http://www.pattakon....ssionDiesel.pdf

It is a little bit old (from the refferences it seems it was published in 1995).
Yet it is experimental work and comes from the "Sloan Automotive Laboratory", MIT.

It shows that the reduction of the lubricant consumption in a Diesel engine (2-stroke or 4-stroke) is vital.

Compare the case of the OPOC engine of EcoMotors / Bill Gates (the piston thrusts heavily onto the hot cylinder wall, above the ports, and needs plenty of lubricant there, making inevitable the increased lube consumption) to the Achates "cross-head" Opposed Piston engine (they claim 0.1 gr/KWh specific lube consumption) and to the PatOP "cross-head" Opposed Piston engine ( http://www.pattakon....ttakonPatOP.htm ).

Then think of the potential of the 2-stroke PatMar architecture ( http://www.pattakon....takonPatMar.htm ) :

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for low specific lube consumption (lower even than the 4-strokes).

As for the spark ignition high compression 4-stroke engines, things are not so different during combustion, even if "the four stroke produces no (visible) smoke at all when using 30:1 fuel/oil mix".

Thanks
Manolis Pattakos