2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello all.

Here is a single cylinder (and single combustion chamber, as well) PatTwo 2-stroke of pattakon:



and here is the CITS two-cylinder design (animation at http://citsengine.com.au/cits-engine-animation/ ) :



With two cooperating cylinders the CITS cannot achieve what the single cylinder PatTwo can (post on page #113).

Can anyone show me a strictly technical advantage of the CITS over the PatTwo?

Do I miss something?

Unless it is better because it takes two cylinders, two pistons, two connecting rods etc . . .

Isn’t this the definition of the “inventive step”, of the “improvement”, of the “evolution”? (i.e. to achieve more with less).

Thanks
Manolis Pattakos

[J.A.W.]

Cheers for that dyno charting explanation effort Manolis..

I thought I'd reiterate the US/Imperial outlook on the dyno charting matter.. ( & in a classic 2T VS 4T comparison).

www.kawtriple.com/mraxl/articles/1973%2 ... bikes2.htm

Re: the `85 Yamaha RD 350 dyno chart TQ/HP cross-over, IMO.. the superimposed lines do cover the 5252 constant..
..I figure it is reasonable that the flatter TQ line continues, while the HP line climbs away up the scale..

& it is also of interest to see the dyno chart of the massive DOHC-4V/4cyl/4T; Yamaha FJR1300..
..since the Yamaha 2T 750/3 figures here: www.hartmaninc.com/catalog/motor-mods-a ... bores.html
.. better it, per the same rpm range.. ( & Pinger, note the 3-1 VS 3-3 pipe dyno comparison)

While evidently less convoluted than the CITS.. FYI, Manolis, Frits Overmars has questioned the gas-flow capabilities
of the separator disc valve - in your 'Pat Two' design shown above..


& P, the Yamaha RD/RZ twins which used the 'balance tube' ( &/or 'boost bottle) had it sited between the carbs, &
the reed valve cages, ( they also used smaller 26mm carbs VS 28mm carbs by previous non-balance pipe RDs) so
each cylinder could draw mixture from both carbs.. ( & the YPVS RD/RZ used a larger diameter pipe as well, again).

I did an experiment with an RDLC ( pre YPVS) using a long ( routed up to the steering head, around 180`& then back), 20mm ID balance pipe, made of clear plastic, which both allowed visualization of the pulses, & worked well, too..

This was on a 180`firing twin, of course, & so the +ve effects, ought to be even more evident - with a 120`triple..

[manolis]

Hello J.A.W.

You write:
“While evidently less convoluted than the CITS Manolis, Frits Overmars has questioned the gas-flow capabilities
of your design shown above..”

The animation intends to explain / to show the differences from the prior art.
Actually it is the same drawing used in the patent application (page #113).



This version:



(pure sinusoidal / harmonic motion of the piston) is not necessarily for a double acting piston.
It can operate as a single acting piston, too (say, with the lower half of the piston removed).


The throttle valve controls the load of the engine:

When fully open, the engine idles.

When fully closed, the engine runs at full load.

However, with a tuned-exhaust things appear more interesting: the peak power can be obtained with the throttle valve open.


With the throttle valve wide open, the flow feels like using an infinite volume crankcase.

Thanks
Manolis Pattakos

[Pinger]

..since the Yamaha 2T 750/3 figures here: www.hartmaninc.com/catalog/motor-mods-a ... bores.html
.. better it, per the same rpm range.. ( & Pinger, note the 3-1 VS 3-3 pipe dyno comparison)

But.... it covers only the upper third of the rev range (circa 6-9k). It is below that expansions tend to fall flat. By my reckoning it is when the returned +ve pulse arrives around BDC and prior, presumably wrecking the scavenge flow from the crankcase and destroying the streaming toward the cylinder head. Guess work as I've never seen any form of analysis as to what actually happens when the +ve pulse arrives earlier than the ideal (40deg before ex' port closure?)

& P, the Yamaha RD/RZ twins which used the 'balance tube' ( &/or 'boost bottle) had it sited between the carbs, &
the reed valve cages, ( they also used smaller 26mm carbs VS 28mm carbs by previous non-balance pipe RDs) so
each cylinder could draw mixture from both carbs.. ( & the YPVS RD/RZ used a larger diameter pipe as well, again).

I did an experiment with an RDLC ( pre YPVS) using a long ( routed up to the steering head, around 180`& then back), 20mm ID balance pipe, made of clear plastic, which both allowed visualization of the pulses, & worked well, too..

This was on a 180`firing twin, of course, & so the +ve effects, ought to be even more evident - with a 120`triple..

Further down your linked page
http://www.totallyamaha.com/
Seems to be intended for reed applications. I'm not entirely convinced of the stated theory. Reeds closing ''suddenly''? Surely they close with the reversal of flow - which given inertia is unlikely to be with quite the snap implied. I don't dispute the ability to draw from both carbs - and guess that is what Yamaha et al intended.

[Pinger]

Can anyone show me a strictly technical advantage of the CITS over the PatTwo?

Assuming your's separates and enables a wet sump? - then no.
Patents?

Unless it is better because it takes two cylinders, two pistons, two connecting rods etc . . .

His flappy valve thing locks him (for good or bad) into cylinders paired in narrow angle V formation. To read his claims anyone could be forgiven for believing he invented the phased crankpin V layout.

[manolis]

Hello Pinger.

You write:
“Assuming your's separates and enables a wet sump? - then no.
Patents? “


At top right of the PatTwo web page (you can directly click on http://www.pattakon.com/pattakonPatTwo.htm ; or you can first get into the www.pattakon.com web site and then select the “2-Stroke Miller” at the menu at left) it writes:

“Intellectual Property: patent GB 2,533,619”


Click on the link https://www.ipo.gov.uk/p-ipsum

and fill the “text box” with GB2533619 to get all the info relative with this patent (granted December 23, 2016) in the specific patent office.

Alternatively, you can open the patent publication (in PDF format) by clicking on:

https://www.ipo.gov.uk/p-ipsum/Document ... cument.pdf


With an oil scraper ring (24) at the lower side of the piston (just above the wrist pin (19)) the 2-stroke engine runs on a wet sub:






For the same invention (the PatTwo project) a Search and Examination is under way in the US-PTO patent Office (i.e. in the USA the invention is in the “patent pending” stage).



Similarly for the rest projects of pattakon:
At top right of the web page for a specific project, you can find the granted patents and then you can open and study them.

Thanks
Manolis Pattakos

[Muniix]

P, a couple of things..

1stly, battery tech will have to get way, way, more advanced, in terms of size, power potential, cost &,
recharge time before they can offer a real/practicable alternative to hydrocarbon fuels.

2ndly, emissions legislation/controls are as much a 'political' issue as a health promotion/technical capability matter..

The inherently fundamental 2T advantages of power density/mass/cost have yet to be specifically applied to cars,
at least in a coordinated package, in the current era, but it does not follow that 2T values thusly - do not still apply..

Agree on all points. Much talk of 'better' batteries but they're not here yet.
Much of the talk I suspect is to prop up share price - while they figure out what they will really replace diesel with.
If RE is required, or even as sole generator, with batteries defining the car's packaging and architecture, exploiting 2T compactness will be a boon. Not convinced CITS fit the bill. Tall before the voice coil injector is fitted and destined to have to 'stand up' due to its wet lubrication. Can't see OEMs liking power valves either - even though they are incredibly effective - twice over.

& there are reasons why ( just as for DI) that the "TJI/lean burn concept" actually applies better to 2T, than to 4T..

As an alternative to voice coil injector - absolutely. 2T is fine throttled so lean burn advantages less obvious. Worth the additional pumping losses for lower combustion temps and lower heat loss? The compromises and trade-offs!....

Hybrid energy storage comprising small Graphene super capitors​ and Li-ion is an effective option for light vehicles. The supercaps can be packaged where convient delivering the high peak current taking this load off the chemical energy storage, reducing heat production. For 50 volt mild hybrid 14 x 18650s or the newer 2170s (30% larger) in seperate banks to assist passive cooling as needed are around a kg each bank, with the cell being ~58g.

New Super capitors using printed multilayer Graphene have been developed here in Oz and being commercialised within two years for limited production. Small and flexible so a 50 volt module can be packaged easily.
Also similarly printed polymer solar cells costing $10 square metre have been printed in 200 metre lengths as well and are only 0.1 mm thick and work better in low light with a 9% conversion efficiency. Also flexible and light weight. A 50 volt mild hybrid solution for motorcycles will be viable by 2020.

The printed solar on bike surface areas provide the parasitic power requirement to keep security system operating and charge energy storage on hybrid Superbikes. They don't need to be angled to the Sun working well with low light.

Think I read on researching​ the supercaps theys have 1/3 Energy density of Li-ion and delivers >1000 amps.

The potential for Graphene to store energy is huge once they can effectively use all the surface area.

"Our supercapacitor is extremely efficient, as it charges in a matter of seconds and holds a larger charge for a longer time because it consists of multiple sheets of graphene,"
http://www.swinburne.edu.au/news/latest ... teries.php

You can only use peak acceleration on the road for a second or two and stay legal so super capitors provide energy for that, especially when combined with IC engine operating at peak power or efficiency.

Think that should keep the Australian advanced materials manufacturing grant application viable with the following Oz Innovations

• Bishop rotary valve

• Turbulent Jet ignition

• Graphene super capitors &
  Polymer solar cells

[Muniix]

What are typical modern 2T Bmep numbers and last of pre DI?
WITH bsfc and any emissions info DI also.

Would it be above 8? Above 10?


Thanks

Ok Marc, here, as a performance 'yardstick'..

According to Frits Overmars, the Aprilia RSA 125cc G.P. machine produced a BMEP of ~17 bar..
( note that the FIM ban on TEL fuel meant reducing comp ratio from ~19.5 to ~15-to-1).

For current 2T snowmobiles, the BMEP figures range from ~10 to ~14 bar..
.. depending on state of tune, from warranty valid - factory standard, to harder hi-po performance tune.

In the link below, noted 2T tuner Olav Aaen discusses developments & notes the advantage of the 3 cylinder lay-out..
..which is yet to be re-introduced in current hi-tech form..
www.amsnow.com/how-to-tech/2009/03/tech ... efficiency

I have previously cited a number of academic research papers in this thread, with comprehensive analyses of emissions..
..such as published by the University of Idaho, & you can read them Marc, if they are of interest.

Thanks for these. I'm generally agnostic about technology, what suits purpose most effectively, after validation. The usual purchase price is not the total cost it is only where it starts. Many don't get this simple fact.

[Tommy Cookers]

J.A.W.'s post 1151am links to the statement 'the dyno doesn't lie'
well Motodd's dyno (the runs of the 1985/6 RD350s) lies and so does the other one
because they measure at a pseudo-road and multiply by an imagined fiddle factor and generate an imaginary crankshaft power/torque 'measurement'

all these road bikes seem to show c. 38-42% of maximum power at 50% of maximum speed (they don't say what happens at 25% speed)
I suspect this is no good for Mr or Mrs or Ms Public's car
(though the Kawasaki 3 tuning/development is interesting)

talking of cars I see that a suggested cause of the Ford Orbital 2 stroke failure was inadequate ring life
around that time Chrysler's EBDI was fancied by some
as was the Bruntel engine
https://www.witpress.com/Secure/elibrar ... 5051FU.pdf
the Collins scotch yoke was mentioned, also the Abingdon X engine (Mr Abingdon or the MG town that was or that rotary valve thing ?)

the 3-1 exhaust behaviour spoken of agrees with my view re F1ish racing - that ....
'banks' of 4 cylinders with paired firing and 4-2 exhaust are ok but 'banks' of 3 with 3-1 only ok if simultaneously fired
and remember the '125 cc Aprilia cylinders' model won't work with 267 cc cylinders because their porting would be too small

btw - DI 2 strokes in production
http://www.kfz-tech.de/Engl/Hersteller/ ... 0E1955.htm
and (note to self)
Vanwall used Bosch 'direct' (ie timed) injection indirectly ie upstream of valve (as was part of Bosch's concept ??)
but 63/65 V6 and flat 12 F1 Ferraris seem to have been true DI

heat dilution (TJI or whatever) makes a good engine for sustained high load use eg power generation using natural gas fuel
literally billions of public money is being spent on such research in Europe
but what good is it in our cars ? ie where does it go efficiencywise when we want 5 or 10 or 20% power ? (it can't be leaned further on liquid fuel)
do people understand that sustained use of more powerthan this is illegal due to things called speed limits ?
a conventional engine is continuously a cheaper, simpler, smaller engine with less friction
buying smaller engines is the proven way to reduce CO2 and cost - but it does require some maturity

no doubt officialdom and manufacturers will as ever collude in developing around heat dilution a structure of false claims and perceptions
this will make them look good for a while or two - as with with the diesel and the EV

[Pinger]

CITS has two patent applications it seems. One each for the flap and by-pass valve.

Previous crosshead marine engines have wet sump covered I guess so no patents there. CITS as I see it is a variation on a theme and only the valve patents prevent anyone productionising it if they wanted to. Skip his valves and go straight to crosshead and wet sump - if you want. Are his valves really that much better than simple reeds? Does his increase in crankcase compression from 1.4-1.5:1 to 1.6:1 really incur throttling losses that justify or need a by-pass valve?

[Muniix]

Because the auto manufacturers were making shed loads of money selling high NOx diesels? The higher the sticker price, the more they make on finance. Complication adds/justifies cost. Just one of the existing prejudices.

I really don't think there is much future in automotive diesel engines, or compression ignition like the GDCI gasoline direct compression ignition as they need to be built with the mass of a Diesel.

The extra mass, expense and complexity required due to CI with high acoustic combustion energy with Diesel and gasoline and emmisions will not be cost effective when EU 7 emmisions are reached.

Yep. I think the tide has turned against Diesel but I doubt the manufacturers know which way to jump right now.
For sure they have GDI but are they going to wait until particulate filters are mandated before fitting them or risk another public outcry when particulate emissions become more widely known? And it is still a complex and expensive engine to build (albeit slightly cheaper than CI).
Full electrification isn't an option for everyone as many (especially in cities where they are of most benefit) do not have access to home charging. At the workplace possibly, but what to do at weekends and holidays? There is also the environmental aspects of mining the required materials. For the manufacturers though, they can market electrification as a new technology and price commensurately. The same can not be said for a 2T ICE - unless it is buried within a heavily electrified vehicle. And still I haven't seen an available off-the -shelf viable 2T. Even if the CITS unit does reach production, I can see aspects of it which OEMs will find objectionable.
At least Renault is giving 2T a whirl but with gas exchange solely by side by side poppet valves (tried and abandoned previously by many) and the slow rpm forced upon it with CI combustion, I'm not convinced it has a bright future.

There is of course the possibility of electric vehicles being hooked up to the electricity grid at all times other than when being driven, giving said grids storage capacity they have hitherto only dreamed of. Smoothing out the demand peaks and troughs easing generation matching over a 24 hour period is there to be had - but so far, no takers.

Are we agreed Muniix that the TJI/lean burn concept (applied to 4T) is the most likely to succeed in the short to medium term?

Main grid power balancing with home power storage is taking off in Oz with more than just trials, new estates and even the power companies themselves are getting involved. The developer of the software has a joint venture with Tesla / someone of note and works with intermittent storage like EVs.
With South Australia having had power blackouts from storm damage, politically blamed on that states high dependence on wind and use of the interconnector. No mention that hot days actually reduces the thermodynamic efficiency of coal power stations when needed most.

My extensive review of all the combustion and ignition systems lead to TJI and then it was awarded Automotive Innovation of the year for 2016.
It has had the most real world testing in F1 and provides all the advantages of CI with reduced peak cylinder pressure.

If you design specifically for it using advanced materials and manufacturing processes for maximum weight savings, a SI version of your engine is going to cost more and be heavier and lose all the advantages especially if you have a low external forces cranktrain.

That puts SI into perspective.

[Muniix]

Hello J.A.W.

You write:
“While evidently less convoluted than the CITS Manolis, Frits Overmars has questioned the gas-flow capabilities
of your design shown above..”

The animation intends to explain / to show the differences from the prior art.
Actually it is the same drawing used in the patent application (page #113).



This version:

http://www.pattakon.com/PatTwo/PatTwo_Harm1.gif

(pure sinusoidal / harmonic motion of the piston) is not necessarily for a double acting piston.
It can operate as a single acting piston, too (say, with the lower half of the piston removed).


The throttle valve controls the load of the engine:

When fully open, the engine idles.

When fully closed, the engine runs at full load.

However, with a tuned-exhaust things appear more interesting: the peak power can be obtained with the throttle valve open.


With the throttle valve wide open, the flow feels like using an infinite volume crankcase.

Thanks
Manolis Pattakos

Here comes another downer.

I'm not sure how much energy is being consumed by the counter balancing system, the coplanar motion will be moving around a lot of air, if not compressing it at certain times unless it is in a vacuum.

That does need some fluid flow analysis to understand. Air moles are definitely moving, the gap between the inner and outer balance mass doesn't give them much area to move into and out of.

Just thinking out loud.

I'm more critical on myself than others. If I've missed an energy loss issue it starts a whole lot of work for myself.

One wants to reduce all losses as much as possible this gives you Bmep for free.

Reducing crackcase oil churning, sheet oil off with coating, reduce Aero losses, Falicon knife rod are good for this especially in dual crank with the scissors like action.
Pulling vacuum from a near vertical baffled​ cavity on the near horizontal cylinder engine. Electric coolant pump.

Traction control harvests excess energy into power storage instead on reducing thermodynamic efficiency.
Increasing engine load increases TE with harvesting so some energy for free, combined with optimistic harvesting and regen braking.
Use the EM motor to assist gear synchronisation especially with harvesting.

[Muniix]

Hello all.

Here is a single cylinder (and single combustion chamber, as well) PatTwo 2-stroke of pattakon:

http://www.pattakon.com/PatTwo/PatTwo10.gif

and here is the CITS two-cylinder design (animation at http://citsengine.com.au/cits-engine-animation/ ) :

http://citsengine.com.au/wp-content/up ... -17.38.jpg

With two cooperating cylinders the CITS cannot achieve what the single cylinder PatTwo can (post on page #113).

Can anyone show me a strictly technical advantage of the CITS over the PatTwo?

Do I miss something?

Unless it is better because it takes two cylinders, two pistons, two connecting rods etc . . .

Isn’t this the definition of the “inventive step”, of the “improvement”, of the “evolution”? (i.e. to achieve more with less).

Thanks
Manolis Pattakos

Yes you do miss something. The Flappy valve is actuated be Pressure Wave dynamics in the CITS engine. This is were he spent a lot of effort to get right. Zero on actual flow or turbulence by his own admission. Thought it was strange he wanted to use loop scavenging and Orbitals DI. Thought each one worked best at the opposite load range or worst depending on how you look at it. Bad scavenging with good DI, or good scavenging with DI at reduced efficiency in the high end.

The DI optimised for marine use, pulling the vessel effectively up on the plane once there it can reduce power.

[Pinger]

The DI optimised for marine use, pulling the vessel effectively up on the plane once there it can reduce power.

Is the above the reason why crossflow (baffle pistons) 2T endured as long for outboards as it did? While less efficient at scavenging at higher delivery ratios than loopers, they only spend a short time at full throttle getting on plane before settling back on the throttle (and delivery ratio) for the (much longer time wise) cruise?

And were they under carbed for high rpm (hence the flat power curve - not peaked - from 3/4 rev range to max rpm) to enable better fuel economy (with less charge loss) at cruise speed?

(I'm looking for confirmation that I've understood these engines correctly - or looking to be corrected).

[J.A.W.]

..since the Yamaha 2T 750/3 figures here: www.hartmaninc.com/catalog/motor-mods-a ... bores.html
.. better it, per the same rpm range.. ( & Pinger, note the 3-1 VS 3-3 pipe dyno comparison)

But.... it covers only the upper third of the rev range (circa 6-9k). It is below that expansions tend to fall flat. By my reckoning it is when the returned +ve pulse arrives around BDC and prior, presumably wrecking the scavenge flow from the crankcase and destroying the streaming toward the cylinder head. Guess work as I've never seen any form of analysis as to what actually happens when the +ve pulse arrives earlier than the ideal (40deg before ex' port closure?)


Further down your linked page...

Seems to be intended for reed applications. I'm not entirely convinced of the stated theory. Reeds closing ''suddenly''?

I think you'd best have another look P, since that dyno chart shows the 3-3 pipes are always ahead of the 3-1 on TQ,
& thus will never give less HP, anywhere in the rpm range.. ..albeit it is a CVT snowmobile chart, though tests on the
Kawasaki triple motorcycles show the same response, with a well-designed pipe/tune combo the 3-3 always wins..

By the 1980s AFAIR, all Yamaha 2T customer bikes were reed valve equipped, & even some of the singles had 'boost bottles'.

& for T-C, Doug Hele at the BSA/Triumph racing dept found the 3-1 collector exhaust to be an overall improvement
on the 3-3 style used by MV-Agusta on their 4T G.P. triples, whereas Peter Williams at Norton tried the Blair designed
2-1 on the racing Commando, but felt the bit of extra top-end power gained by discreet 2-2 pipes was worthwhile..

Here (linked below) is a dyno chart of a tuned Kawasaki 750 with 3-1, it worked well with the tune, but still lost up top..

www.kawi2strokes.com/forum/viewtopic.ph ... 6&start=20