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2-stroke uniflow with 4-stroke lubrication and scuffing resistance


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#1 manolis

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Posted 28 March 2012 - 11:16

The PatMar(ine) or PatMar is a two-stroke port-less through-scavenged crosshead engine having four-stroke lubrication, four-stroke specific lube consumption and four-stroke scuffing resistance.

The “cylinder lubrication problem” is described in details by Ole Christensen of Wartsila, in their Technical Journal of February 2010 at http://www.pattakon....nal_02_2010.pdf

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(above is the s35 (i.e. 350mm bore), the smallest low-speed direct-drive 2-stroke marine engine of MAN)

Besides being the maker of the world’s most powerful medium speed 4-stroke engine (Wartsila-64, 2.000 KW per cylinder), Wartsila – Sulzer is also a maker of the giant two-stroke marine and power-station direct-drive low-speed engines.


The PatMar(ine) (or PatMar) at http://www.pattakon....takonPatMar.htm is through scavenging and at the same time its cylinder liner is rid of ports.

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The combustion chamber of the PatMar is as rid of lubricating oil (and oil mist) as the best four stroke marine engines.

The PatMar can be made with one exhaust valve (on the cylinder head) and one inlet valve (on the piston crown) per cylinder.
The PatMar can be made with four exhaust valves (on the cylinder head) and another four intake valves (on the piston crown) per cylinder.
And so on.

That is, neither the combustion chamber shape, nor the injector(s) location, are worse than those in the 4-stroke of similar bore. On the contrary, the cross-head architecture enables extreme “stroke to bore” ratios (like 4.5), which gives way more “compact” combustion chamber with lower surface to volume ratio than in the four-stroke of same capacity per cylinder.

For instance:
The 4-stroke Wartsila 64 has 640mm bore and 960mm stroke.
A PatMar can be made with the same bore (640mm) and 640*4.5=2880mm stroke (typical value in the state-of-the-art low speed 2-stroke marine engines).
It is easy to calculate that the “surface to volume” ratio of the first is about double than the second.

Besides, the lubrication of the cross-head slippers and guides is so good that even with extremely short connecting rods (con-rod to stroke ratio around 1.15) the overall thermal efficiency of the long stroke low speed marine engines is the best among all thermal engines (and this operating with cheap, heavy fuel oil.

Your objections?


The above are for marine and power station application.

What about the use of the PatMar as the prime mover for heavy-duty trucks?

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Why not a 90mm bore / 400mm stroke four-in-line (10 lit 2-stroke) with crossplane crankshaft (even firing) and full balance? If it makes its maximum torque at 600 rpm and its maximum power at 1000 rpm, what is the problem?
The loads on the pistons and on the connecting rods compare to those of a conventional 2 liter four stroke Diesel of a small car.

Objections?

Questions?

Thanks
Manolis Pattakos

Edited by manolis, 01 April 2012 - 06:11.


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#2 gruntguru

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Posted 28 March 2012 - 12:12

Hi Manolis
I read your linked page in full when you first posted it. I also read the Ole Christensen paper in full. Very interesting - no arguments with any of your claims as with most of your inventions. Is there any progress towards commercialisation of any of your stuff?

#3 cheapracer

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Posted 28 March 2012 - 14:22


I presume the top of your red intake chambers have a set of compression rings (sealed to the blue piston inner)?

I also presume you are using positive displacement of intake on the down-stroke via a one-way valve?

You think the intake valve will transfer sufficient heat away? Maybe multiple valves would provide more valve seat area to get rid of heat.

I think the ship engine market is an excellent one, I had planned to pursue it as well so I should mention to you to get out now while you can. I will be starting the Patent process on my engine this weekend. Sorry in advance.

Relevant useless info -The 13,000 tonne cargo ship I was on last weekend uses 20 tonnes of bunker oil per day at ideal speed. Fuel is their biggest single cost so any savings is worth considering for them. The biggest container ships in the world burn around $100,000 in fuel per day.



#4 manolis

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Posted 28 March 2012 - 16:32

Hi Manolis
I read your linked page in full when you first posted it. I also read the Ole Christensen paper in full. Very interesting - no arguments with any of your claims as with most of your inventions. Is there any progress towards commercialisation of any of your stuff?


Gruntguru, thanks.

For the moment no project of pattakon is in mass production.


The PatMar suits to Wartsila – Sulzer (according the paper of Ole Christensen, they are looking for such a solution) and to MAN.
Try to communicate with the Technical Heads in Wartsila or MAN, and you will understand how things work (or, more correctly, how things do not work).
We cannot afford to modify a marine engine to PatMar; but we are going to make a PatMar power generation set (90mm bore, 400mm stroke, 600 rpm) to see how the theory works in the real world (fuel efficiency, maintenance intervals).


Take a look at http://www.pattakon....ttakonHydro.htm and theoretically compare it with the MultiAir of Fiat.
Could MultiAir ever be equal to PatAir?
Then you propose to Fiat / Alfa Romeo / Lancia to take the car and compare it with theirs.
What do you think was the response of Fiat?


Thanks
Manolis Pattakos


#5 manolis

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Posted 28 March 2012 - 17:26

Cheapracer,

"I presume the top of your red intake chambers have a set of compression rings (sealed to the blue piston inner)?"

Yes, you are right. They replace the rings that seal the “rod” of the conventional 2-stroke that connects the piston to the wrist pin.


"I also presume you are using positive displacement of intake on the down-stroke via a one-way valve?"

No, this is not necessary. In the state-of-the-art giant marine 2-stroke engines, the turbocharger provides compressed air to a plenum surrounding the intake ports at the bottom of the cylinder. In the PatMar the plenum surrounds the bottom end of the pant-legs.

On the other hand, with one or two one-way valves per cylinder the engine intergrades a zero cost volumetric charger enabling easy starting, operation without turbocharger etc. You can combine both ways: after the engine starting, you can deactivate the one-way valves, or like the twin charger of VW.


"You think the intake valve will transfer sufficient heat away? Maybe multiple valves would provide more valve seat area to get rid of heat."

The problem is not how hot the intake valve and the piston crown run, but how cold. All the fresh air passes through the piston crown and cools everything. Compare this to the case of the conventional 2-stroke.

Thanks
Manolis Pattakos

#6 cheapracer

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Posted 29 March 2012 - 07:30

"I also presume you are using positive displacement of intake on the down-stroke via a one-way valve?"

No, this is not necessary. In the state-of-the-art giant marine 2-stroke engines, the turbocharger provides compressed air to a plenum surrounding the intake ports at the bottom of the cylinder. In the PatMar the plenum surrounds the bottom end of the pant-legs.


If it were mine I would be using the obvious positive air displacement facility (blue chamber volume beneath the intake valve at TDC and the volume of the red intake chamber ports) - it looks about 3:1, a good balance between heat and pressure. This would require individual one way valves as close to the bottom of the red intake chamber ports as possible.

A turbo can act as a one way valve but it's a long way upstream with a lot of volume inbetween and might not be ideal at low revs - although that may not be important for a large marine application (if you can get it started).

For truck use you would need individual one way valves for each cylinder otherwise off boost you will have a situation where your air tank pressure is equalised because the cylinders intake actions are balanced (one piston is always going up (providing negative pressure) as another is coming down (providing positive pressure) - status quo).

I like the way you figured eventually that the piston speed has slowed enough at that point to automatically open the intake valves safely, I note in other earlier examples you had unnecessary mechanisms to do that function.

Edited by cheapracer, 29 March 2012 - 07:43.


#7 manolis

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Posted 29 March 2012 - 15:04

Cheapracer,

You are right: in some applications the one way valves have advantages.

But in the big low-speed 2-stroke marine engines they are not used.
This causes a reciprocation of air between the space underside the piston crown and the intake plenum around the intake ports.
During the upwards motion of the piston, air from the plenum fills the space underside the piston crown, and later, when the piston moves downwards, this air is pushed back to the intake plenum.
It is OK (they have the top brake thermal efficiency).


An approach for understanding the PatMar is to see it as a modification / improvement on a 2-stroke marine engine: it avoids the inlet ports on the cylinder liner lowering the specific lube consumption and increasing the scuffing resistance.


Another approach for understanding the PatMar is as a modification of a conventional 4-stroke engine to PatMar. All the valves on the cylinder head become exhaust valves. The intake valves are on the piston crown and follow the piston.

The change from trunk-piston to crosshead allows way shorter connecting rods to be used. This way the engine height stays the same.
With the same bmep (somewhere between 20 and 25 bar in most big 2 and 4 stroke engines) the power of the engine doubles without significant side effects.


“I like the way you figured eventually that the piston speed has slowed enough at that point to automatically open the intake valves safely, I note in other earlier examples you had unnecessary mechanisms to do that function.”

I think you mean the PatPortLess engine at http://www.pattakon....PatPortLess.htm which is also a 2-stroke uniflow with 4-stroke lubrication:

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A “camshaft” mechanism is necessary, otherwise the control of the valve motion is lost and the valve rebounds on its seat.


Even in a low speed PatMar engine the smooth landing of the intake valve is significant. For safe intake valve opening (and especially for safe intake valve closing), and for noise reduction, you need a simple mechanism to provide the necessary elasticity and dumping in order to control the valve motion. If the valve rebounds on the piston crown, the control is lost.

Thanks
Manolis Pattakos

Edited by manolis, 29 March 2012 - 15:07.


#8 cheapracer

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Posted 29 March 2012 - 15:55

A “camshaft” mechanism is necessary, otherwise the control of the valve motion is lost and the valve rebounds on its seat.


I don't agree, especially with your experience of the Patair and VVT systems, I think designing a simple hydraulic damper is a no-brainer compared to the cost, weight and complications of the mechanisms you currently display.

Even a simple conical shaped spring would have a suitable and very effective rising rate as well as spreading the load better into the piston head - such as the purple coloured one here ...

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#9 eta

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Posted 29 March 2012 - 16:56

Hi everyone, this is my first post in the Technical forum

Manolis I do have two questions:
don´t you think that the intake air will be mixed with the oil dust in the crank case? That would have an effect on the oil consumption and the emissions

Which valve timings are needed, because I wonder if there is a problem when you need to increase the valve opening duration, the speed of the valve touching the lower guidance will increase significantly?

#10 Wolf

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Posted 29 March 2012 - 21:12

Manolis, I like the design... :up:

But I was wondering, same as Cheapracer, as to possible use of pants as substitute for crankcase compression. The reason is my uneducated ™ guess that it would probably be for the best not to have mixture from turbocharger fed directly to the pants, because it would reduce efficiency of the engine (smaller pressure differential above and below the piston). Maybe it's a bit more complicated, but I've seen an interesting design that might suit your engine quite well. ISTR that Hispano-Suiza had interesting supercharged engine (off top of my head, I'd say pre-WWI) which had dual intake- mixture with atmospheric pressure was fed into the cylinder for most of the intake stroke, and late into the stroke supercharged mixture was fed (regulated by a poppet valve). In a similar vein, maybe you'd consider having a port for mixture at atmospheric pressure, letting the piston compress it, and then releasingf the turbocharged mixture through a rotary valve on another port. (and, should you need it, although I see no possible gain from it, I could give you my design for variable-timing rotary valve*) If you're interested to see Hispano-Suiza design, I could try to dig up a drawing I've seen somewhere.

* it would be (in principle) more suited for high revving engines, but I was told that it's in practice very unsuitable...

#11 manolis

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Posted 30 March 2012 - 04:09

I don't agree, especially with your experience of the Patair and VVT systems, I think designing a simple hydraulic damper is a no-brainer compared to the cost, weight and complications of the mechanisms you currently display.

Even a simple conical shaped spring would have a suitable and very effective rising rate as well as spreading the load better into the piston head - such as the purple coloured one here ...

Posted Image


Cheapracer,

Think about the conical spring:
During compression, combustion and expansion the intake valve – and the spring - follows the motion of the piston.
As the piston approaches the BDC it comes a moment the moving valve lands on the top of the immovable “pants”. That moment the speed of the piston is “small”, but not zero.
Example:
For a 2500 mm stroke marine running at 90 rpm (7.5m/sec mean piston speed), the moment the valve lands onto the pants the piston speed is (depending on the selected timing) about 4 m/sec (the program balance at http://www.pattakon....attakonEduc.htm helps a lot in such calculations).
If you leave the valve to hit like a hummer on the pants, you have a problem (noise, reliability, control).
If, during the upward motion of the piston, you leave “uncontrolled” the valve, it rebounds on the piston crown.
And the spring (especially when it is compressed) has to not restrict the passage of the air from the space underside the piston crown to the combustion chamber.

For the hummering:

Take something as heavy (and as hard) as the intake valve of a big PatMar and keep it at 0.8 meters above the floor. Then leave it to fall. The moment it lands on the floor, its speed is 4m/sec. Operating the big PatMar at 90 rpm is like repeating the previous fall-and-hit 10800 times per hour.

If in a car engine a mechanical valve lash adjuster is not properly aligned, the camshaft, even at idling, hits like a hammer the valve (the speed is less than 4 m/sec) and you hear the characteristic noise. With the proper alignment, the starting and ending ramps of the camlobe “take” this gap without allowing – the moment the valve starts or stops moving – a speed-difference above a limit.

One of the big problems of the MultiAir was to smooth the landing of the valve. The hydraulic mechanism is made so that a little before the valve landing the hydraulic system acts like a dumper.

For the low and medium speed PatMar engines the necessary mechanism is quite simple and cheap and compact. I will add a couple of drawings in the pattakon site to show a version.

For the PatPortLess things are more complicated (but conventional).

In both cases the question is, as always, “does the gain worth the pain?”

Thanks
Manolis Pattakos


#12 manolis

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Posted 30 March 2012 - 04:24

Hi everyone, this is my first post in the Technical forum

Manolis I do have two questions:
don´t you think that the intake air will be mixed with the oil dust in the crank case? That would have an effect on the oil consumption and the emissions

Which valve timings are needed, because I wonder if there is a problem when you need to increase the valve opening duration, the speed of the valve touching the lower guidance will increase significantly?


Hello eta.

The space underside the piston crown – and the air inside it – is completely isolated from the crankcase and the oil pan. This is what the “red pants” is doing. An oil scrapper ring at the “pants waist” keeps the lubricating oil away from the incoming air, just like the oil scrapper ring of the conventional 4-stroke keeps the lubricating oil away from the combustion chamber. Take a look at the drawings at http://www.pattakon....takonPatMar.htm

In the big low speed crosshead marine engines, the exhaust valves are used to vary the timing (the intake ports on the cylinder bottom are fixed).
In the PatMar the exhaust valves can vary the timing, as in the conventional 2-strokes.
Alternatively, with a system like the HyDesmo (at http://www.pattakon....akonHyDesmo.htm ) you can vary the timing of the intake valve(s), too, improving a lot the variability of the engine. For instance, the intake valve can open even after the BDC, which is impossible for the ported marine 2-stroke engines.

Thanks
Manolis Pattakos


#13 manolis

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Posted 30 March 2012 - 04:58

Manolis, I like the design... :up:
. . .
* it would be (in principle) more suited for high revving engines, but I was told that it's in practice very unsuitable...


Wolf,

As I understand it, during the upwards motion of the piston, ambient air fills the space underside the piston crown, then the air is trapped and compressed, then the space underside the piston crown starts, somehow, communicating with the intake plenum that contains compressed air from the turbocharger / cooler, and then the intake valve opens for the scavenging.
This idea fits to the conventional low-speed crosshead 2-stroke marine engine, too. But the current design is the simplest one: an intake plenum (for the compressed air from the turbocharger) directly communicating with the intake ports on the cylinder liner.

When a new idea is proposed, it has to be kept as conventional and as simple as possible.

The same is true for the rotary valve:
Why in a new design like the PatMar,
which is a two-stroke port-less through-scavenged crosshead engine having four-stroke lubrication, four-stroke specific lube consumption and four-stroke scuffing resistance,
to put a rotary valve?

And on the other hand: why to put around a new rotary valve design not a conventional engine but an unconventional one?

Thank you
Manolis Pattakos


#14 cheapracer

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Posted 30 March 2012 - 09:20

Think about the conical spring:


I did that's why I offered it. It allows a softer initial seat pressure while rapidly rising in pressure as the valve comes away from the seat. As for closing, don't think it's a big issue, use damper springs as well.

As well, each landing will be assisted by the cushioning of the compressed air spring under the head of the valve.

So lets say you have aprox. 5 psi intake pressure (turbo), that will give us aprox 25 psi of crankcase pressure acting on say a 300mm valve, would offer around 100 pounds of pressure under the head of the valve when it hits the pants.


#15 cheapracer

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Posted 30 March 2012 - 09:24

then the space underside the piston crown starts, somehow, communicating with the intake plenum


"somehow" must equal a one way valve.


#16 manolis

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Posted 30 March 2012 - 10:38

I did that's why I offered it.
. . .


Thanks Cheapracer.

I already added four drawings in the http://www.pattakon....takonPatMar.htm page.

Posted Image

In the simplest case (without one-way valves), the cushioning action - you proposed - of the compressed air underside the intake valve head is cancelled by the compressed gas over the intake valve head inside the cylinder.

Posted Image



""somehow" must equal a one way valve."

A one way valve cannot work in the arrangement proposed by Wolf because what is needed is to stop the flow of compressed air from the plenum (containing compressed air from the turbocharger / cooler) to the space underside the piston with the lower - until about the piston middle stroke- pressure.

"Somehow" the communication of those two spaces must be controlled.

Manolis Pattakos


#17 cheapracer

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Posted 30 March 2012 - 10:48

the compressed air underside the intake valve head is cancelled by the compressed gas over the intake valve head inside the cylinder.


I hope not, I would certainly expect that the exhaust was well open by then.

A "landing" spring on the pants is a good thing too.

A conical spring will still help to spread some loads across the piston rather than offering it's loads to the weakest point.


#18 Wolf

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Posted 30 March 2012 - 11:07

Not neccessarily... When you say 'one-way valve' it somehow implies something like reed valve, which is opened by pressure differential and therefore would not work as desired/described (one would need a valve that would open when there is least pressure differential, not the biggest)... The way I see it, reed valve would open around TDC and fill the pants with compressed mixture, and doing so would create much bigger 'mechanical losses'. Manolis, I think direct communication of plenum with the pants is for the same reason not the best idea (I can try to illustrate it a bit later to show my point- but could you tell me what the turbocharger pressures usually are?).


Manolis, at least I got how it should work correctly. But can you be more specific about that "communicating" part? Like Cheapy, I believe there should be something preventing the communication before the piston reaches the vicinity of BDC, and we believe it should be a valve of a sort... Thew reason I propsed rotary (disc, to be more precise) valve is that it seems the simplest, easiest and most practical solution to valving problem. Firstly, it's a still 2-stroke engine and as such can use cranchaft to operate valves*. Secondly, proximity of pants (and intake ports) to crankshaft makes disc valve ideal for the purpose.


* and I'd also point out that 4-stroke technology is no stranger to rotary valves- off top of my head, I can remember Aspin, Crossle and Norton motorcycle engine designs with rotary valves (I happen to have 1942 automotive handbook that devoted a fair bit of pages to rotary and sleeve valve designs... I'd say, close to 50 pages)

#19 cheapracer

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Posted 30 March 2012 - 13:02

Not neccessarily... When you say 'one-way valve' it somehow implies something like reed valve, which is opened by pressure differential and therefore would not work as desired/described (one would need a valve that would open when there is least pressure differential, not the biggest)... The way I see it, reed valve would open around TDC and fill the pants with compressed mixture, and doing so would create much bigger 'mechanical losses'.


I admit to being a bit confused - I am specifically commenting on improvements to the Patmar engine shown in the first post.

-Piston goes up draws air past individual reed valves (any valve that performs the function), positioned at start of the individual pant's intake tract (and not sharing other intake tract), filling the pants and expanding piston cavity till TDC.
-Piston changes direction, reed valve shuts and air is compressing almost to the volume of the pants as piston races towards BDC.
-Intake valve opens and the compressed pants air flows past the intake valve into the combustion chamber aided by the already escaping energy of the exhaust.

Cycle finished. Applicable to NA or pressure charged engine. Plenum chamber or not upstream of reed valve makes no difference to operation cycle.

What "mixture" are you referring too?






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#20 cheapracer

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Posted 30 March 2012 - 13:07

I propsed rotary (disc, to be more precise) valve is that it seems the simplest, easiest and most practical solution to valving problem. Firstly, it's a still 2-stroke engine and as such can use cranchaft to operate valves*. Secondly, proximity of pants (and intake ports) to crankshaft makes disc valve ideal for the purpose.


It would be the first inline 4 cylinder 2 stroke I know of with (classic crankshaft mounted) disc valves.

Would love to know how/where you're going to mount them ...




#21 manolis

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Posted 30 March 2012 - 13:14

Not neccessarily... I'd say, close to 50 pages)


Wolf,

I think the pressure you are looking for is 3 to 4 bars.

In the conventional 2-stroke marine – look at the MAN S35 at the top of the post – air from the plenum fills the space underside the piston crown, then it returns to the plenum and finally enters the cylinder through the intake ports.
It seems inefficient, however these are the top fuel-efficient engines.

Please don’t misunderstand my posts.
The rotary valve you propose (which, as I understand it, has nothing to do with the supercharging method you mentioned) may be perfect. But you have to, “somehow”, control its motion. And the access in the space underside the piston crown is difficult.
Besides, it is quite risky to combine two unconventional ideas in a new project.

The controllable communication of the space underside the piston crown (i.e. the “pants”) with the plenum may also give some advantage, but does it justify the added complication?

The conventional intake poppet valve, on the other hand, is not necessarily the perfect choice, but it works quite well and reliably. And its control is easy and cheap.

Thanks
Manolis Pattakos



#22 desmo

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Posted 30 March 2012 - 14:40

It would be the first inline 4 cylinder 2 stroke I know of with (classic crankshaft mounted) disc valves.

Would love to know how/where you're going to mount them ...


Maybe you haven't seen this Helmut Fath disc valve 4 cylinder boxer. Not an inline but interesting nevertheless.

http://www.zweitakte.....redor 500.htm

#23 cheapracer

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Posted 30 March 2012 - 15:30

Maybe you haven't seen this Helmut Fath disc valve 4 cylinder boxer. Not an inline but interesting nevertheless.

http://www.zweitakte.....redor 500.htm


Suzuki have 3 or 4 World Championships in the 500 class with a disc valve square 4 as well as the RG500 production bike - the point is, as your example, is that the drive can be easily taken off the ends of the crank or in these cases, cranks as they have 2, but serious problems when attempted between cylinders.

http://www.google.co...0l0ll0l0.frgbld.



#24 Wolf

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Posted 30 March 2012 - 15:44

Cheapy, I was being pedantic by using 'mixture' instead of 'air'... And yes, you're talking about classic 'crankcase compression' principle, but I think it highly unsuitable for charged engine- just think what 'backpressure' would be on the underside of the piston if initial pressure below it was 2-3 bar. :eek: Would piston even reach BDC?

As for disc valves, I don't see much problem with installation... as long as we don't try to place valves and intake between cylinders*. Besides, those pants would make any type (inline, V, boxer or whatever) suitable for individual cylinder 'crankcase compression' and possibly disc valves.

* it's not necessary to place the 'port' on the pants/cylinder, if that's what you were thinking...

Manolis, I intend to take a better look to see if it would be justified (no crankcase compression vs crankcase compression (+ turbocharging) vs simple turbocharging). As for my disc valve proposal, I meant it as means for 'blocking' plenum/turbocharger air from entering pants until piston poppet valve was opened (to have both crankcase compression of atmospheric air and turbocharging, or just to have atmospheric pressure below piston until intake cycle to increase efficiency).

#25 gruntguru

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Posted 31 March 2012 - 09:29

Lots of interesting ideas from Cheapy and Wolf but I have to agree with Manny. The engines we are discussing are already the most efficient in the world. The charging of these engines has been optimised over many years of development. Manny's concept is to combine the advantages of both two and four stroke low speed marine diesels essentially eliminating the one serious drawback of the two stroke class. There is little potential benefit in introducing additional unproven technologies.

#26 cheapracer

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Posted 31 March 2012 - 10:06

The engines we are discussing are already the most efficient in the world. . There is little potential benefit in introducing additional unproven technologies.


They are efficient because of their size, fuel/air burns in the same time, regardless of size, and in an engine that size, the charge has plenty of time to completely burn and then some, even in a 2 stroke. Note scaled down versions of these "World's most efficient engines" are not used anywhere else like Mum's VW Golf.

I don't get how you guys think this is going to work at low revs when the turbo offers no boost and you have crankcase balance - how is the intake going to offer a charge of air? This is why most 2 strokes use a supercharger and I am stating that this is what's needed via the pants with a one way valve.

You could have a mechanical compound system or spin the turbo up with a supplementry electric motor or small diesel engine until the exhaust catches up but that's putting a dent in efficiency/cost.



There is little potential benefit in introducing additional unproven technologies.


With respect, the Patmar is a 3D animation.

Edited by cheapracer, 31 March 2012 - 10:07.


#27 Wolf

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Posted 31 March 2012 - 18:54

GG- we're just throwing in the ideas, but I would argue that by displacing turbocharged air below piston while it moves downwards is wasting fuel/energy/power. A rough guesstimate indicates that it's in the ballpark of 40-80kW per cylinder depending on the pressure (2 or 3 bar), which could be 4-9% of power output per cylinder*... I'm inclined if we get rid of those losses (or decrease them perceptibly), PatMar has a better chance of finding its way on the market.

* the guesstimate was based on 350M engine data (350mm bore, 1550mm stroke, 167rpm and 870kW/cylinder); pumping losses (p*V) are compared to atmospheric pressure (p0*V)

#28 manolis

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Posted 31 March 2012 - 19:14

Let me put this pure technical problem differently:


Case 1.

Take a big 2-stroke crosshead marine engine, like the RT-96 (960mm bore, 2500mm stroke) and compare it with its “theoretical twin” PatMar.

What I see is:

Similar power and torque.

True four stroke lubrication.

True four stroke scuffing resistance (the rings move along a port-less cylinder).

Lower construction cost:
The conventional 2-stroke needs special equipment that provides the necessary lube dosage to the cylinder liner. Read how proud for their CLU4 (cylinder lubrication unit 4th generation) is SKF (and Wartsila, and MAN) and imagine how much the system of CLU4 units – and their control – costs.
Besides the cost of the CLUs, it is also the fact that throwing away the CLUs, the engine gets rid of the CLUs malfunctions (reliability).

Lower running cost from:
the reduced lube oil consumption (4 times more expensive price than the heavy oil fuel)
and the longer intervals between overhauls (scuffing resistance).

Lower emissions: no lubricant-oil-mist inside the combustion chamber.


Case 2.

Take the most powerful 4-stroke marine engine (Wartsila 64 with 640mm bore, 960mm stroke) and compare it with its “theoretical” modification to PatMar.

What I see is:

Double power.

Similar specific fuel consumption.

Lower specific lube consumption.

Similar cost.

Same external dimensions.

More reliable (the cylinder is rid of thrust loads).

Smoother operation. For odd number of cylinders it doubles the number of combustions per crank rotation.


Case 3

Take the “imaginary” 10 lit truck engine described at http://www.pattakon....P.htm#CrossHead (4-in-line, even firing, full-balanced, “cross-plane” crankshaft, very-long-stroke, low revving, WITH one-way valves in the pants).

At http://www.pattakon....P.htm#CrossHead it is explained (for the case of the PatOP, but it is applicable to PatMar, too) how the one-way valves are by-passed when the turbocharger pressure is adequately high, enabling a simple twin-charge system.

What I see is a number of advantages as compared to the conventional truck engines.


What do you see for the above three cases?




Cheapracer,

What you write is true: “the Patmar is a 3D animation.”

Every project starts with an idea / spark, proceeds as a paper drawing, continuous as 3D-animation and so on.

On the other hand:
If you know another way, different than the PatMar and the PatPortLess, to achieve true 4-stroke lubrication and scuffing resistance in a 2-stroke uniflow engine, please let me know. This is what I want to hear.

The modification of an RT-96 to PatMar is easy for Wartsila / Sulzer, but not for us.


The PatMar is a 3-D animation, but the PatAir:

Posted Image

is not a 3-D animation.

In the “Wankel compression ratio limit” thread I wrote a couple of things about the PatAir.

In production neither the long duration of the intake camlobes of the PatAir adds any cost, at all, nor the ECU reprogramming adds any cost, at all.

Isn’t it obvious?

So, without any additional cost or complication, at all, the available modes of the MultiAir / TwinAir / UniAir of Fiat / Schaeffler-INA double.

Isn’t it obvious, too?

For two years now the Technical Heads of Fiat and Saeffler-INA are hiding.
What is sure is that they know their problem:
Their cars are the most fuel efficient in the official cycle, but they are not good in the real driving.
In most multiple-car-tests (convoy), the Fiat MultiAir and Alfa Romeo MultiAir cars cannot compete other conventional-technology cars in the overall fuel efficiency.


Wolf: the 3 bars of the intake air after the turbocharger has nothing to do with the pressure difference between the space underside the piston crown and the intake plenum.


Thanks
Manolis Pattakos


#29 gruntguru

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Posted 01 April 2012 - 02:09

They are efficient because of their size, fuel/air burns in the same time, regardless of size, and in an engine that size, the charge has plenty of time to completely burn and then some, even in a 2 stroke.

Sure, 53% efficiency is not possible in smaller engines. On the other hand 53% doesn't just happen when you build a big Diesel engine. If you think improving on that, is as easy as coming up with a good idea, you are dreaming.

I don't get how you guys think this is going to work at low revs when the turbo offers no boost and you have crankcase balance - how is the intake going to offer a charge of air? This is why most 2 strokes use a supercharger and I am stating that this is what's needed via the pants with a one way valve.

You could have a mechanical compound system or spin the turbo up with a supplementry electric motor or small diesel engine until the exhaust catches up but that's putting a dent in efficiency/cost.

Perhaps you should brush up on the way it is done now before trying to re-invent the wheel. http://www.marinedie...rbo_charger.htm Using the pants/crankcase compression for scavenging would put a dent in the efficiency under all operating conditions. A supplementary electric blower on the other hand, has a low capital cost and a small efficiency cost for starting and occasional low-speed operation. Manny is simply leaving that aspect of the existing design alone because it works well already.

#30 cheapracer

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Posted 01 April 2012 - 04:38

Perhaps you should brush up on the way it is done now before trying to re-invent the wheel.

Manny is simply leaving that aspect of the existing design alone because it works well already.


Perhaps you should read the very first sentence of the very link you provided and relate it to what I have posted, the sentence that states: "A 2 stroke crosshead engine must be supplied with air above atmospheric pressure for it to work".

At no point has Man nominated what pressure charging system he figures he will use and I am offering the simplest, cheapest, most efficient and well proven one available that immediately does away with all the other nonsense.



GG- we're just throwing in the ideas, but I would argue that by displacing turbocharged air below piston while it moves downwards is wasting fuel/energy/power.


There a a few million extremely powerful and efficient 2 strokes using crankcase compression that I can argue that with. In early days of fast 2 strokes, they pumped like hell even adding extra pistons to gain volume/crankcase compression, but with a better understanding of exhaust flow characteristics and using the inherent energy available to draw air through, the crankcase compression is very light in the modern era (about 1.5:1).

There is opportunity at a number of levels in Man's design to regulate and dictate what the crankcase compression ratio could be and simple pressure valves to bleed off excess if required - all no brainers.



#31 cheapracer

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Posted 01 April 2012 - 04:54

Cheapracer,

What you write is true: “the Patmar is a 3D animation.”

Every project starts with an idea / spark, proceeds as a paper drawing, continuous as 3D-animation and so on.


As English isn't your first language please note that when a sentence begins "With respect...", that means a factual statement with no offense in anyway. :)

I admire and respect the bulk of your work.


On the other hand:
If you know another way, different than the PatMar and the PatPortLess, to achieve true 4-stroke lubrication and scuffing resistance in a 2-stroke uniflow engine, please let me know. This is what I want to hear.


Why yes I do and when the Patent process (that's underway now) is at the relative point, I will let you know  ;)

Please consider opening an ice cream shop as all other engine designs in the world are about to become redundant overnight  ;)

Oh, nearly forget, "Investor Relations" ... :lol:

#32 gruntguru

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Posted 01 April 2012 - 05:57

Perhaps you should read the very first sentence of the very link you provided and relate it to what I have posted, the sentence that states: "A 2 stroke crosshead engine must be supplied with air above atmospheric pressure for it to work".

At no point has Man nominated what pressure charging system he figures he will use and I am offering the simplest, cheapest, most efficient and well proven one available that immediately does away with all the other nonsense.

Try reading paragraph 2 of the link I posted.
Your offering is not efficient.
Man has nominated that existing systems be used for scavenge.

There a a few million extremely powerful and efficient 2 strokes using crankcase compression that I can argue that with. In early days of fast 2 strokes, they pumped like hell even adding extra pistons to gain volume/crankcase compression, but with a better understanding of exhaust flow characteristics and using the inherent energy available to draw air through, the crankcase compression is very light in the modern era (about 1.5:1).

There is opportunity at a number of levels in Man's design to regulate and dictate what the crankcase compression ratio could be and simple pressure valves to bleed off excess if required - all no brainers.

The engines you speak of bear little similarity to low speed marine diesels which are highly supercharged, ultra-efficient and optimised for constant speed and constant load.

#33 manolis

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Posted 01 April 2012 - 06:55

The first link at the top of the thread was wrong and is now corrected (it is the analysis of the cylinder lubrication in the 2-stroke marine Diesels, in Wartsila’s Technical Journal, Febr 2010).

Quote from this publication of Wartsila / Sulzer:

Some years ago, an Inner Lubrication System concept was studied at Wartsila, and a prototype was developed and tested with positive results. Based on this, and on some good results from applying an oil scraper ring in the piston ring pack on a Wartsila RTA96C engine, where an oil supply from the piston side might be advantageous, it has been decided to take this concept up again and develop it to a commercially applicable level.

A slightly more ambitious idea is to apply the four-stroke trunk piston engine cylinder lubrication concept to the two-stroke crosshead engine, i.e. to “over-lubricate” the cylinder liner, apply an oil scraper ring, and then collect the surplus oil, clean it, and recycle it. This will of course be a radical change of concept, and whether or not it is viable remains to be demonstrated, but an outline exists and a patent is pending. The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines.



As English isn't your first language please note that when a sentence begins "With respect...", that means a factual statement with no offense in anyway. :)
I admire and respect the bulk of your work.
. . .
Why yes I do and when the Patent process (that's underway now) is at the relative point, I will let you know ;)


From what I understand with my English,

Cheapracer does not know anything “open to the public” that makes what the PatMar promises and what Wartsila and Sulzer seem to be looking for:
“The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines.”

Cheapracer I do hope to see some 3D animations of your idea after being patent pending (it takes a couple of weeks, as I know).

Until then it is more productive and interesting to forget your secret idea and to focus on the straight technical questions set in my last post (the three different cases asking for objections by all the forum members), which are still unanswered.

Thank you
Manolis Pattakos


#34 cheapracer

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Posted 01 April 2012 - 08:39

Try reading paragraph 2 of the link I posted.


Has no bearing on what I said. Turbo, supercharged, crankcase with valve, air compressor, - doesn't matter, that engine needs above atmo pressure or it will not start or run.


Your offering is not efficient.


Yeah, sure, of course it's not.


Man has nominated that existing systems be used for scavenge.


I must have missed it but it's certainly not in the first post(?).

The engines you speak of bear little similarity to low speed marine diesels which are highly supercharged, ultra-efficient and optimised for constant speed and constant load.


Oh, I didn't realise that physics changed from engine to engine.


From what I understand with my English,

Cheapracer does not know anything “open to the public” that makes what the PatMar promises and what Wartsila and Sulzer seem to be looking for:


As I said, English clearly isn't your first language as I understand it all just fine, but ....


“The aim is to increase scuffing resistance and to achieve the same low specific oil consumption level as on the four-stroke trunk piston engines.”


..... I am not interested in that side of it because it is obvious it will work and it's not rocket science what you have done - congratulations for being the one that did figure a new system out and achieving those goals. Otherwise I choose to discuss areas of the engine that are of interest me.


Until then it is more productive and interesting to forget your secret idea and to focus on the straight technical questions set in my last post.


Maybe for you it is :lol:


Case 2.

Take the most powerful 4-stroke marine engine (Wartsila 64 with 640mm bore, 960mm stroke) and compare it with its “theoretical” modification to PatMar.

What I see is:

Double power.


No, one of the biggest mis-conceptions I see on the net is that a 2stroke will make twice the power of a 4 stroke because it fires twice as often. This is a basic misunderstand of the very basics of how both work.


#35 manolis

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Posted 01 April 2012 - 18:39

No, one of the biggest mis-conceptions I see on the net is that a 2stroke will make twice the power of a 4 stroke because it fires twice as often. This is a basic misunderstand of the very basics of how both work.


Cheapracer,

Your "a 2stroke will make twice the power of a 4 stroke because it fires twice as often" has nothing to do with what I wrote.

Take a look at the brake mean effective pressure of the low and medium speed marine Diesel engines currently in use.

Depending on the size of the engine, the bmep of the 2-stroke and of the 4-stroke is similar (from 20 bars for the big ones, to above 25 bars for the small ones).

This makes double the power of the 2-stroke as compaired to the 4-stroke of same speed and displacement.

Thanks
Manolis Pattakos

#36 gruntguru

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Posted 02 April 2012 - 02:50

Has no bearing on what I said. Turbo, supercharged, crankcase with valve, air compressor, - doesn't matter, that engine needs above atmo pressure or it will not start or run.

Except that paragraph 2 directly contradicts your very next statement: "At no point has Man nominated what pressure charging system he figures he will use and I am offering the simplest, cheapest, most efficient and well proven one available that immediately does away with all the other nonsense."

I must have missed it but it's certainly not in the first post(?).

The fact that he didn't mention the scavenge method indicates that his modification does not require changes to the (already very efficient) scavenging system. Anyone with a basic understanding of these engines wouldn't be questioning Manny's choice of scavenge sytem.

Oh, I didn't realise that physics changed from engine to engine.

It doesn't. That doesn't mean sweeping statements about the operation of a 10,000 rpm, SI, NA, crankcase+loop scavenged two stroke can be applied to a 100 rpm, Diesel, highly supercharged, uniflow two stroke.

No, one of the biggest mis-conceptions I see on the net is that a 2stroke will make twice the power of a 4 stroke because it fires twice as often. This is a basic misunderstand of the very basics of how both work.

For the engine type we are discussing, double power is a reasonable approximation.

#37 malbear

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Posted 02 April 2012 - 07:33

As English isn't your first language please note that when a sentence begins "With respect...", that means a factual statement with no offense in anyway. :)

I admire and respect the bulk of your work.


so do I ( malbeare)



Why yes I do and when the Patent process (that's underway now) is at the relative point, I will let you know ;)

Please consider opening an ice cream shop as all other engine designs in the world are about to become redundant overnight ;)

Oh, nearly forget, "Investor Relations" ... :lol:


I wish you both the best of luck.
I would advise you to produce BSFC figures for various loads and revs. then get them confirmed by a reputable uni or testing house. armed with these figures then approach manufacturers or gear up to supply a small niche market yourself and wait for the approaches.
Do not get involved with someone who is Deceptively evil, deviously cunning, Machiavellian, predatory, vindictive, psychopathic, habitually lying. parasitic schoolyard bully. whos aim is to milk the concept for as much cash as possible ( for golf fees and house renovations, cars), even hinder development in order to maintain a more cash is needed to get over the line investor spruke.


#38 gruntguru

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Posted 02 April 2012 - 08:49

All very good advice. :)
In Manny's case BSFC shouldn't be an issue as he has modified an existing design to eliminate a lubrication issue. Although he has modified the intake path, that should be a positive since the engine would have more intake timing options than the port scavenged original.



#39 MatsNorway

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Posted 02 April 2012 - 15:50

Cheapracer,
This makes double the power of the 2-stroke as compaired to the 4-stroke of same speed and displacement.


I thought that also meant double the cooling requirements.
And a two stroke i guess is less efficient pr beat but better overall when it comes to big marine diesels or it would not have been a discussion?

Edited by MatsNorway, 02 April 2012 - 15:51.


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#40 cheapracer

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Posted 02 April 2012 - 16:23

Man has nominated that existing systems be used for scavenge.

The fact that he didn't mention the scavenge method



WTF? Alcohol maybe?


Anyone with a basic understanding of these engines wouldn't be questioning Manny's choice of scavenge sytem.


A basic understanding of what, a glorified bicycle pump? :lol:

No one questioned Manny's choice of scavenge system because it wasn't mentioned - DUH.





Cheapracer,

Your "a 2stroke will make twice the power of a 4 stroke because it fires twice as often" has nothing to do with what I wrote.


What I see is: Double power.


This makes double the power of the 2-stroke as compaired to the 4-stroke of same speed and displacement.


Manolis Pattakos


For the engine type we are discussing, double power is a reasonable approximation.



Yeah, sure, good luck with all that. :yawnface:



#41 cheapracer

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Posted 02 April 2012 - 17:10

I would advise you to produce BSFC figures for various loads and revs.


I see it as correct for your offerings because you need to factually demonstrate that your modification is an improvement on a current foundation, whereas I am offering a completely new foundation that I will leave to others to improve upon - we are at opposite ends of the spectrum.


Do not get involved with someone who is Deceptively evil, deviously cunning, Machiavellian, predatory, vindictive, psychopathic, habitually lying. parasitic schoolyard bully. whos aim is to milk the concept for as much cash as possible ( for golf fees and house renovations, cars), even hinder development in order to maintain a more cash is needed to get over the line investor spruke.


:lol: - I'm laffing at the post's wording, not the seriousness of the actual situation.

#42 Wolf

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Posted 02 April 2012 - 18:09

I'm not sure how am I getting things wrong... :confused: Current 2-stroke marine diesels feed turbocharged air through cylinder port into the cylinder (and the pressure below cylinder is crankcase pressure i.e. atmospheric pressure). PatMar feeds the turbocharged air through the poppet valve in piston. The latter option means that the space below the valve (and piston) must contain turbocharged air, which is as Manolis has said 2-3 bars. If that is the case, and I haven't seen any alternative way of providing the turbocharged air, then the losses because of decreased pressure differential above and below piston will be according to my estimate. :confused: If it doesn't use turbocharged air it's limiting its performance and applicability (it will have less power and fuel efficiency than turbocharged engines), and that's why I'm pointing it out- the problem can most likely be solved if it's recognized and given proper attention.

Edited by Wolf, 02 April 2012 - 18:10.


#43 cheapracer

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Posted 02 April 2012 - 19:10

Current 2-stroke marine diesels feed turbocharged air through cylinder ports into the cylinder


Yes ...

PatMar feeds the turbocharged air through the poppet valve in piston.


Yes ...

PatMar feeds the turbocharged air through the poppet valve in piston. The latter option means that the space below the valve (and piston) must contain turbocharged air


Yes ...

If that is the case, and I haven't seen any alternative way of providing the turbocharged air,


Mmm correct ...

Then the losses because of decreased pressure differential above and below piston will be according to my estimate.


Nope.

The 4 cylinder Patmar as offered in post 1, with the turbo attached that of course we all knew about because we weren't told about it, will offer the turbo boost pressure only to the inlet valve because when the piston comes down, another one is going up so therefore crankcase pressure is balanced and does not change.

If it was a single cylinder then your analysis would be correct (depending on the volumes involved).

Edited by cheapracer, 02 April 2012 - 19:15.


#44 Wolf

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Posted 02 April 2012 - 19:34

:lol: We were doing great until this point:

Nope.

The 4 cylinder Patmar as offered in post 1, with the turbo attached that of course we all knew about because we weren't told about it, will offer the turbo boost pressure only to the inlet valve because when the piston comes down, another one is going up so therefore crankcase pressure is balanced and does not change.

If it was a single cylinder then your analysis would be correct (depending on the volumes involved).


OK, here's my point, illustrated by pic from PatMar web page:

Posted Image


The piston is sliding between cylinder walls and pants, and it's obvious that underside of the piston is at intake pressure (2-3 bars instead of 1 bar of conventional 2-stroke) of the turbocharged air filling the pants*. I'm assuming no compression going below piston, only that because of greater pressure below piston, the force acting on it will be reduced by same amount (or same can be achieved by saying that loss of useful work will be pressure increase x volume displaced). The reason I'm harping on this issue, is because those pants can be seen as redeeming quality of this concept, if one was to keep them at atmospheric pressure and devise the other way of feeding the turbocharged air to the valve.

* if there were no pants, the crankcase should contain the intake air at the pressure indicated, so the loss would be the same (2-3 bars crankcase pressure vs 1 bar)

#45 gruntguru

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Posted 02 April 2012 - 23:28

because of greater pressure below piston, the force acting on it will be reduced by same amount (or same can be achieved by saying that loss of useful work will be pressure increase x volume displaced). The reason I'm harping on this issue, is because those pants can be seen as redeeming quality of this concept, if one was to keep them at atmospheric pressure and devise the other way of feeding the turbocharged air to the valve.

I don't see any loss of useful work. The negative work of the piston pushing down against crankcase pressure is recovered as positive work during the upstroke with crankcase pressure helping to push the piston up.

#46 gruntguru

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Posted 02 April 2012 - 23:38

A basic understanding of what, a glorified bicycle pump? :lol:

Yes, they are pretty simple. Pity you didn't take the time to understand them a little before telling Manny how to suck eggs.

No one questioned Manny's choice of scavenge system because it wasn't mentioned - DUH.

It was pretty obvious to me. Manny designed a system to solve a lubrication issue by replacing the scavenge ports with a poppet valve. No mention of the air charging system means that wasn't part of the redesign.

#47 Wolf

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Posted 03 April 2012 - 00:04

I don't see any loss of useful work. The negative work of the piston pushing down against crankcase pressure is recovered as positive work during the upstroke with crankcase pressure helping to push the piston up.


I don't think it's that simple, and here's a link that might be relevant: electric crankcase pumps. My guess is that Honda and Ten Kate guys saw enough reason to use them and seeing they got banned, FIM guys must also have (and after the banning, I'd think Ten Kate lost a bit of their edge*).

* a friend of mine who follows bikes much more than I do, being racing mechanic, would say they were basically reduced from front runners to midfielders

#48 desmo

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Posted 03 April 2012 - 03:48

I don't think it's that simple, and here's a link that might be relevant: electric crankcase pumps. My guess is that Honda and Ten Kate guys saw enough reason to use them and seeing they got banned, FIM guys must also have (and after the banning, I'd think Ten Kate lost a bit of their edge*).

* a friend of mine who follows bikes much more than I do, being racing mechanic, would say they were basically reduced from front runners to midfielders


Wouldn't it be likely those were oil scavenge pumps to reduce windage losses like those used in F1 for ages? I suppose running the crankcases at a significant partial vacuum would reduce fmeps due to air drag, but would the benefit outweigh the power cost of evacuating the crankcase chambers beyond what was necessary to scavenge the oil?. Hmmm is there a any significant change in volumes below the pistons in a V as the crankshaft rotates? Wouldn't the crank geometry determine that? Do racing bikes run segmented crankcases?

OK, I'll stop with the silly questions.

#49 manolis

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Posted 03 April 2012 - 04:54

Cheapracer,

I prefer a simple-minded idea that really solves a long existing problem, than a sophisticated idea being, actually, “a solution in search of a problem” as Grumbles wrote for TCVJ.

In my last post I write that the 4-stroke and the 2-stroke Marine engines operate at similar brake mean effective pressure; this is so not because I say so, but because the technical specifications, provided by the manufacturers to the ship-owners, say so.

It seems that the big 2-stroke and the big 4-stroke marine Diesels achieve the best equilibrium between fuel efficiency, emissions, reliability etc at 20 to 25 bars bmep.

Unless I am wrong, the power per cylinder is the bmep multiplied by the capacity of the cylinder and by the number of combustions per second.

Which means that a modified to PatMar Wartsila 64 can make 4 MW per cylinder (the 4-stroke Wartsila 64 makes 2MW per cylinder).

Cheaprace, if you have a better explanation, please explain.
It is a Technical forum and everyone is expecting to learn something.

Wolf: "Then the losses because of decreased pressure differential above and below piston will be according to my estimate."

Cheapracer to Wolf: "Nope.
The 4 cylinder Patmar as offered in post 1, with the turbo attached that of course we all knew about because we weren't told about it, will offer the turbo boost pressure only to the inlet valve because when the piston comes down, another one is going up so therefore crankcase pressure is balanced and does not change.
If it was a single cylinder then your analysis would be correct (depending on the volumes involved)."


It seems you are confused about how the PatMar works.

The crankcase has nothing to do with the aspiration / breathing of the PatMar. This is the inventive step: to isolate/seal the space underside the piston crown from the crankcase and from the oil pan, in order to have, among others, the 4-stroke lubrication advantages.


Quote from “ http://www.pattakon....takonPatMar.htm ”:

The pants (red) of the PatMar engine comprise ports (the pant-legs) for the communication of the space underside the piston crown with the air tank (brown). The crosshead (blue), the wrist pin (yellow) and the connecting rod (green) move between the pant-legs. The crosshead slippers (cyan) thrust onto the crosshead guides (not shown).

An oil scraper ring on the piston, scraps the surplus oil from the cylinder liner (brown) back to the oil pan, as in the four-stroke engines.
An oil scraper ring on the "waist" of the pants scraps the oil from the inner surface of the piston skirt back to the oil pan.
The empty space between the cylinder liner and the piston skirt is for the scraped oil.

Posted Image

The friction of the rings between the inner surface of the piston and the "pants waist" is more or less the friction of the sealing rings between the piston rod and the casing of the conventional low speed 2-stroke crosshead engine.

The space underside the piston crown is sealed from the crankcase.


What is so difficult about this simple-minded idea?

The space above and underside the piston crown is sealed from the crankcase (by the typical piston rings sliding along the cylinder liner, and by the rings on the pants-waist sliding along the inner surface of the “piston skirt”).

Air from the brown intake plenum fills the space underside the piston crown entering through the pant-legs.

Wolf:

The "pressure-difference" necessary for this air motion has nothing to do with the pressure inside the plenum.
A couple of tenths of a bar “pressure-difference” is adequate to actuate the motion of the air from the intake plenum towards the space underside the piston crown (as the piston goes up) and backwards (as the piston lowers). So don’t be confused by the 3 or 4 bars inside the intake piping. They are different things.
Think also that immediately after the exhaust valve and before the turbo-charger the pressure is way higher than the ambient pressure.
Think also that inside the cylinder the pressure of a heavily turbocharged 2-stroke marine never drops close to 1 bar.

If the PatAir is to run without turbo-charging, instead of an additional mechanical compressorm one-way valve(s) can be used to trap the air inside the pants and inside the space underside the piston crown for the next scavenging. Depending on where the one-way valve(s) is (are) located, the “dead volume” of the built-in no-cost piston-type volumetric scavenging pump is defined.

A further step is to add a turbocharger and to control the path of the air: easy starting with the built-in scavenging pump and high power density with the turbocharger (which uses a part of the – otherwise – lost energy of the exhaust gas). It is better to deactivate (or simply to bypass) the one-way valves when the turbo-charger pressure is over a limit (as explained at http://www.pattakon....P.htm#CrossHead ).

In the old Detroit Diesels the roots compressor was used for a scavenging-ratio of about 1.0, i.e. the roots was for the scavenging and not for “mechanical supercharging”. Later they added a turbo-charger to increase the specific power.

Thanks
Manolis Pattakos


#50 cheapracer

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Posted 03 April 2012 - 06:07

Cheapracer to Wolf: "Nope.
The 4 cylinder Patmar as offered in post 1, with the turbo attached that of course we all knew about because we weren't told about it, will offer the turbo boost pressure only to the inlet valve because when the piston comes down, another one is going up so therefore crankcase pressure is balanced and does not change.
If it was a single cylinder then your analysis would be correct (depending on the volumes involved)."


It seems you are confused about how the PatMar works.

The crankcase has nothing to do with the aspiration / breathing of the PatMar.

I'm not confused at all, I am referring to the crankcase area beneath the pistons just as you are but for your benefit, and as you have more than one area of crankcase sealed off from one another, lets refer to it for your sake as the "crankcase PIV" (pants intake volume).

And here I will write exactly the same sentence to Wolf suitably modified;

"Nope.
The 4 cylinder Patmar as offered in post 1, will offer the turbo boost pressure only to the inlet valve because when the piston comes down, another one is going up so therefore crankcase PIV pressure is balanced and does not change.
If it was a single cylinder then your analysis would be correct (depending on the volumes involved)."


And just for the record, your engine technically is "crankcase induction".


Cheapracer to Wolf: [i]"Nope.

This is the inventive step: to isolate/seal the space underside the piston crown from the crankcase and from the oil pan, in order to have, among others, the 4-stroke lubrication advantages.

There's been a number of engines with the same premise ie; 2 stroke with isolated 4 stroke lubrication.


Wolf:


If the PatAir is to run without turbo-charging, instead of an additional mechanical compressorm one-way valve(s) can be used to trap the air inside the pants and inside the space underside the piston crown for the next scavenging. Depending on where the one-way valve(s) is (are) located, the “dead volume” of the built-in no-cost piston-type volumetric scavenging pump is defined.

Yeah, well this is now appearing in this thread and your website after I, then Wolf, schooled you on it.


Yes, they are pretty simple. Pity you didn't take the time to understand them a little before telling Manny how to suck eggs.

I don't quite know what your line is Mate but if you want to play this silly ego game then please refer to the "Wankel Compression Ratio" thread posts 18, 19, 20 and 21 where I schooled you on modern 2 strokes, a subject far more complicated and more technical than this engine ever will be.

I suggest that Manny doesn't have a handle on his own engine either, specifically the self balancing effect of the (valveless) crankcase PIV.

Adoration seems to be blinding you.

Edited by cheapracer, 03 April 2012 - 06:16.