2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello all.

Manolis wrote:

“On the other hand, with the asymmetric timing, the duration of the exhaust can be substantially shorter, shifting all the ports lower on the cylinder.”



In these plots / drawings / animations:











one can see a significant advantage of the 2-stroke with the asymmetrical transfer, over the conventional 2-stroke.


Start with a conventional 2-stroke requiring, say, 90 crankshaft degrees transfer duration (i.e. the transfer opens 45 degrees before the BDC and closes 45 degrees after the BDC).

The exhaust has to open substantially earlier, say at 65 degrees before the BDC, to provide time in order the pressure in the cylinder to drop before the starting of the transfer.



Looked at from a different viewpoint, the valve-time-area and the duration of the exhaust are substantially larger / longer than the valve-time-are and the duration of the “intake” (“intake”: the ports (the transfer ports) through which the mixture enters into the cylinder):





In the 4-strokes the opposite is the case: the exhaust valve-time-area is substantially smaller than the intake valve-time-area (the pressure at the end of the power stroke helps the fast evacuation of the cylinder).

For instance, in the Ducati Panigale (the top 4-stroke) the ratio of the exhaust valve-time-area to the intake valve-time-area is circa 2/3 (66%).



In the 2-strokes the opposite is the case, only because it cannot be otherwise.



With the asymmetric transfer, the transfer of the 2-stroke can start and end substantially later.

The exhaust needs not to last more than the transfer, any longer.

The exhaust valve-time-area needs not to be larger than the transfer valve-time-area, any longer.

The exhaust can open substantially later milking more power from the fuel.

With the exhaust closing before the transfer, the mixture previously lost in the exhaust reduces.

Etc, etc.



Youtube video at https://www.youtube.com/watch?v=aXvRaVqiHxs


Do I miss something?

Thanks
Manolis Pattakos

[Muniix]

Here we go, now I've given up smoking, I have to maintain the 'smokers advantage' by going outside every few hours, coming back in with the solution to an issue. It's a documented fact, measurable in the IT industry. I choose to catch out false vendor claims.

Hello Pinger.

You write:

“When I look I see the pressure dropping from 15psi to around 11psi (at lowest). 4psi is 0.27 bar.
The other pressure drop (on the downward stroke) is the compressed charge reducing to cylinder pressure when the transfer ports are open.”

Because the plot is for full load (wide open throttle).

With closed throttle and 1.6:1 primary compression ratio, the pressure drops near 0.5 bar (7.5psi).

You also write:

“Close off (throttle) a cylinder that has as clearance volume 1/10th of the swept volume, draw the piston down, and the pressure drop will be much larger. “

How much larger can be the drop of the pressure?

Zero is the absolute vacuum.

To the residual gas of the 4-stroke with the 10:1 compression ratio (theoretically 1/10 of the cylinder capacity, more than double in practice due to the overlap) it is added a quantity of fresh mixture.

This quantity, in atmospheric pressure, is about 1/5 of the capacity of the cylinder.

Not difficult calculations based on the data provided at http://www.pattakon.com/pattakonIdleValve.htm :

http://www.pattakon.com/VVA_Idle/img004.png .

for the Honda - VVA-roller prototype engine of pattakon:

http://www.pattakon.com/VVA_Idle/VVA_Idle_Valves.jpg

http://www.pattakon.com/VVA_Idle/img005.png

No it's not a difficult calculation, just seems you never start with the facts, how one can innovate based on erroneous opinions and data and produce a successful outcome, you can't except by error.
Having to generate your own data because favourable data doesn't exist elsewhere so you can refer to it is referred to as fraud by the law.

Adding the residual gas (circa, 2/10 of the capacity of the cylinder) and the charge required for the engine to idle (circa, another 2/10 of the capacity of the cylinder), the cylinder is not so empty.

With 40% of the capacity of the cylinder occupied, the actual compression (or expansion) ratio is not the geometrical one (10:1) but 2.5:1, or so.

This is where variable phasing could be valuable, or pressure wave dynamics would be useful in both two or four stroke engines.

The engines you refer to achieve far better scavenging and residual exhaust gas than you claim or calculate.

It EGR is typically between 4-40% depending on load / throttle opening. This is even discussed in one of the papers you have referred to, so stop cherry picking information to suit your Explitieve.

It's well understood you want the nitrogen in the EGR to moderate combustion using ultra lean and EGR is generally accepted as ideal. It reduces peak cylinder pressure, friction, torsional issues,... Providing not just improved combustion and powertrain advantages but also design and manufacturing optimisation possibilities.

I think you should find another field to work in, clearly you do not have the rationality and clear analytical mind to achieve success accept by accident. Leave the world and it's issues to people who can more effectively engineer solutions.

Please stop pushing your other inventions on this forum, it is not for commercial use. There are other forums for that. Providing relevant accurate information is one thing but engineering falsehoods is not.

Clearly we would realise your designs would likely have issues you regularly fail to understand and address, nobody is going to waste the time give a second thought to. I tried once showing your stuff to a real powertrain engineer it was the only time I looked stupid in that discussion.

When an issue is brought to your attention your behaviour is not rational. You go off on a typical don't look their, look over here or come up with some easily debunked justification of it.

You also write:

“Question: On the design of yours you showed with the last of the transfer occurring after exhaust port closure. How so with no remaining crankcase pressure and a rising piston? I'm thinking, the flow will reverse back into the crankcase - as happens with conventional porting even.”

For low rpm the timing shown in the animation is aggressive.

But for high revving, wherein the inertia of the air gets in play, the timing should be even wilder.

On the other hand, with the asymmetric timing, the duration of the exhaust can be substantially shorter, shifting all the ports lower on the cylinder.


Thanks
Manolis Pattakos

Identifying all the relevant issues and then Innovating based on all the facts.

This is where simulation can eliminate confirmation bias and provide a greater understanding of what is really happening, provided you have the analytical and visualisation mind and tools. If you don't have the tools you create them as needed as I have and verify them using testing and behaviour frameworks so it picks up any change that may effect some previous functionality​.

This is why the old Automotive model is being replaced by a smarter model, the most successful examples are all from the information technology industry. Tesla the Neo 9 taking the lap time record at the 'ring' with electric car. Parasitic losses are more easily addressed with electric motors just put x amount of our printer solar panels on the body surface. We are now mass producing 200 metre lengths of 9% efficient 0.1 mm thick light weight solar that works well in low light, doesn't need to be as perpendicular to the light for $10 a square metre. Just have to make it fit with the visual design of the vehicle! Charging​ our printed multi layer Graphene super capitors used in a hybrid system for example so one has instant torque available to meet grip force at any moment, harvest excess energy or operating the IC engine at a more ideal load.

Australia had to shutdown it's Auto industry based on the old model with its high dependency on subsidies even if it was the most efficient in the world so it could build the new one. Why I have been busy leading up to our recent budget, add my mass to lobying for an advanced materials and processes industry with success. Because we thought it through and had evidence on our side understanding the forces changing the market. A high income workforce can be a major manufacturer.

[Muniix]

For a two stroke version of my Mutant Newton engine as I've code named it. The ducted and baffled cavity used by the vacuum pump could be used for the intake.

Looking at the latest KTM I note that is where it's intake appears to be. It also has dual injection and a fuel rail, some covers and housings what else have people noted in the KTM packaging?

A dry crankshaft setup is needed. The under piston oil jets and oil flow through the dual rods used to cool piston crown, scavenging pump and dry sump re thought making a steel piston less viable. That is a potential disadvantage, thou at the smaller bore size less so.

Picture the dual crank arrangement with the cylinder inclined ~20 degrees off horizontal, the crankshafts one above each other same inclination from the vertical in the support bridge. As the piston descends it pushes the under piston air up into the near vertical cavity behind the crankshafts all carefully formed for efficient fluid flow the duct and cavity providing assistance to air oil seperation and drain back the heavier oil moles into the scavenging pump pickup of the dry sump arrangement. Crankshaft counter balance/web geometry all optimised to reduce Aero and oil churning losses. The cranktrain requires high tolerance manufacturing anyway so why not implement an arrangement that reduces external forces to improve engine durability and vibration as a side effect. Simplifies the rest of the engine design. Confines the forces into a optimised system all forces, bearing sizing, geometry taken into consideration.

Maybe a pressure wave supercharger to provide the intake pressure on a two stroke engine, after the first couple of cycles on start would be running well. Make a good research project. Integration into the packaging some novel way. High charge pressure with EGR if needed with TJI and conventional HP direct injection. Two stroke engines are pressure wave engines. There must be a clever meeting of these two systems that is an improvement and simple. A through flow PWS not the Hyprex style with inlet and exhaust at opposite ends.

Also on calling Polaris Swiss Auto about the Hyprex PWS seems Polaris hasn't just shut down Victory, Mission motors they have sold off the IP assets and components. So no more PWS availability from Swiss Auto. That is a shame.
No reply from the German company that has bought it.

Oh no.. by the beard of the Vader..
..well, Marc, it looks like we're actually getting you over to the 'dark side' - too.. "May the 2T power be with you.."

It's an interesting intellectual challenge! What can come out of it can only be good, knowledge, discoveries...

I was always the one that was shangied to solve others problems. It's a curse I was born with, dad got shangied to the Womera to work on the Blue Streak missile project. Interesting things he hasn't divulged due to official secrets act!

[J.A.W.]

A number of Yamaha 2T patents of interest, inc' early TPI; throttle control by exhaust, & 3 cylinder car engine fitment.

https://www.google.com/patents/US3687118

https://www.google.com/patents/US5553579

https://www.google.com/patents/EP0647804A1?cl=en

[gruntguru]

It will pull in lowest ratio until it hits a torque peak before shifting out.

At WOT a CVT will (should) shift at the power (not torque) peak.

[Pinger]

It will pull in lowest ratio until it hits a torque peak before shifting out.

At WOT a CVT will (should) shift at the power (not torque) peak.

It wont as the secondary clutch is torque sensitive so needs to see the torque drop a fraction to begin shiftout. It scarcely matters with engines where torque and power peaks are mere 500 rpm apart - if apart at all (RGV 250 has both peaks at same rpm - by way of an example of hi-po 2T).
Some CVTs calibrate a slight initial overshoot though (on the primary clutch I think).

[J.A.W.]

... that's ok the FIM has banned my valve gear anyway...

When did the FIM do that Marc?
I know the FIA has stipulated poppet valve 4T piston engines only - for F1.. & has bans on 2Ts/rotary pistons & valves..
.. but AFAIR, while the FIM regs do also require cylindrical piston 4Ts, they actually don't mention valve gear..

[Muniix]

"At WOT a CVT will (should) shift at the power (not torque) peak."

Ideally it should operate within the least variance of peak power, once just past it then reduce ratio. Hybrid can add efficiency into the behaviour.

Due to being able to remote pair with Engineers at any time sharing their screen and video conferencing with them gives useful freedom.

Referring to Manolis Asymmetrical port timings.

The following durations have been identified from quoted timings;

115 Inlet
90 Conventional xfr
110 Asymmetric xfr
130 Exhaust

Quoting port and transfer timings without volumes and ducting geometry that will likely be backing them up does not fully describe the system.

How can someone asses and comment on it.

As these are actually important to the systems functioning. There are more attributes needed for a complete description else it is merely aspirational.

Hello all.

Manolis wrote:

“On the other hand, with the asymmetric timing, the duration of the exhaust can be substantially shorter, shifting all the ports lower on the cylinder.”



In these plots / drawings / animations:

http://www.pattakon.com/PatAT/PatAT_Timing.gif

http://www.pattakon.com/PatAT/PatATi_Timing.gif

http://www.pattakon.com/PatAT/PatATi_model1_timing.gif

http://www.pattakon.com/PatAT/PatATi_model1_ports.jpg

http://www.pattakon.com/PatAT/PatATi_model1.gif

one can see a significant advantage of the 2-stroke with the asymmetrical transfer, over the conventional 2-stroke.

Start with a conventional 2-stroke requiring, say, 90 crankshaft degrees transfer duration (i.e. the transfer opens 45 degrees before the BDC and closes 45 degrees after the BDC).

The exhaust has to open substantially earlier, say at 65 degrees before the BDC, to provide time in order the pressure in the cylinder to drop before the starting of the transfer.

Looked at from a different viewpoint, the valve-time-area and the duration of the exhaust are substantially larger / longer than the valve-time-are and the duration of the “intake” (“intake”: the ports (the transfer ports) through which the mixture enters into the cylinder):

http://slideplayer.com/slide/3619985/13 ... closed.jpg

In the 4-strokes the opposite is the case: the exhaust valve-time-area is substantially smaller than the intake valve-time-area (the pressure at the end of the power stroke helps the fast evacuation of the cylinder).

For instance, in the Ducati Panigale (the top 4-stroke) the ratio of the exhaust valve-time-area to the intake valve-time-area is circa 2/3 (66%).

In the 2-strokes the opposite is the case, only because it cannot be otherwise.

With the asymmetric transfer, the transfer of the 2-stroke can start and end substantially later.

The exhaust needs not to last more than the transfer, any longer.

The exhaust valve-time-area needs not to be larger than the transfer valve-time-area, any longer.

The exhaust can open substantially later milking more power from the fuel.

With the exhaust closing before the transfer, the mixture previously lost in the exhaust reduces.

Etc, etc.

http://www.pattakon.com/Fly_files/PatATi_First_Run.jpg

Youtube video at https://www.youtube.com/watch?v=aXvRaVqiHxs

Do I miss something?

Thanks
Manolis Pattakos

It is not a Ducati Panigale it is the Superquatro engine. The compromised single purpose, now dead end design. The Testastretta engine is under constant evolution and will continue to do so, having been recently enhanced with dual spark then variable valve timing. The Panigale due to its poor in cylinder turbulence needs fairly extreme ignition timing, the newer 1299 being better than the original but still up to 50 degrees at times.

Marc

[gruntguru]

Referring to Manolis Asymmetrical put timings.

The following durations have been identified from quoted timings;

115 Inlet
90 Conventional xfr
110 Asymmetric xfr
130 Exhaust

Quoting port and transfer timings without volumes and ducting geometry that will likely be backing them up does not fully describe the system.

How can someone asses and comment on it.

Who cares? The timing values are not the invention.

Koenigsegg (eg) invents a computer-controlled valve system. If they then publish some suggested valve timings, do we rubbish their invention because those timings don't make sense?

[Tommy Cookers]

a CVT at WOT won't operate for properly peak power rpm unless there is some intelligence in control - as with car CVT since c.1990 but not before
and that rpm will be witheld at the lowest roadspeeds to stay within the transmission's output torque limits

but every possible throttle opening etc has its corresponding peak torque and power rpms
and we drive the public highway by using every possible throttle opening and continuously vary those rpms
so the control intelligence and devices are essential, in part to fit people's expectations and habits and so avoid complaints
(and they can even be perversely rigged by design to provide fake manual shift behaviour for sporty effect as the MG F)

unless our vehicle has very low weight and (relative to this) very high aero or other quasi-fluid drag ie scooter, snowmobile or boat use
where bobweights and springs or whatever non-intelligent control is a suitably useful approximation to the above

[Muniix]

Referring to Manolis Asymmetrical put timings.

The following durations have been identified from quoted timings;

115 Inlet
90 Conventional xfr
110 Asymmetric xfr
130 Exhaust

Quoting port and transfer timings without volumes and ducting geometry that will likely be backing them up does not fully describe the system.

How can someone asses and comment on it.

Who cares? The timing values are not the invention.

Koenigsegg (eg) invents a computer-controlled valve system. If they then publish some suggested valve timings, do we rubbish their invention because those timings don't make sense?

Koenigsegg valve system isn't fixed timing, just an actuation system. So not really relevant.

[manolis]

Hello all.

Among others the asymmetric transfer:

cancels the limitation of the conventional 2-stroke according which the transfer duration has to be substantially shorter (circa 50 crankshaft degrees) that the exhaust duration,

cancels the limitation of the conventional 2-stroke according which the exhaust has to open too early to offer time to the pressure to drop without restraining “too-much” the duration of the transfer,

cancels the limitation of the conventional 2-stroke according which the exhaust will remain for some 20-25 crank degrees open after the closing of the transfer, giving the chance to the charge (air of mixture) to escape,

cancels the limitations of the conventional 2-stroke for turbocharging.






Quote from Manolis’ last post:

“in the Ducati Panigale (the top 4-stroke) the ratio of the exhaust valve-time-area to the intake valve-time-area is circa 2/3 (66%).

In the 2-strokes the opposite is the case, only because it cannot be otherwise.”

End of Quote.


Look at the above quote from a “reverse” viewpoint:

Suppose one reverses the rotation direction of the Ducati Panigale Superleggera 1299 engine, adjusts properly the spark and swaps the intakes with the exhausts at the two sides of the cylinder heads.

In other words: the small valves are now for the intake, the big valves are for the exhaust.

The exhaust valve-time-area gets some 50% larger than the intake valve-time-area (more or less as in the conventional 2-strokes), while the total valve-time-area remains the same.

The power has significant reasons to drop from 215PS to less than 150PS.


Thanks
Manolis Pattakos

[Pinger]

http://www.jhis.co.uk/ICE/Help/images/D21DSPVDiag.png

Manolis:
In the above data, in the lower right hand corner are listed timings. What does the last row (BOA and BCA) relate to?

The fuel is listed as 'paraffin'. Is this a 'diesel' (HCCI to be more precise) not glow plug motor?

Any idea if the fuel is 100% paraffin (I'd expect equal thirds of ether, paraffin and castor oil)?

[J.A.W.]

Hello all.

Among others the asymmetric transfer:

cancels the limitation of the conventional 2-stroke according which the transfer duration has to be substantially shorter (circa 50 crankshaft degrees) that the exhaust duration,

cancels the limitation of the conventional 2-stroke according which the exhaust has to open too early to offer time to the pressure to drop without restraining “too-much” the duration of the transfer,

cancels the limitation of the conventional 2-stroke according which the exhaust will remain for some 20-25 crank degrees open after the closing of the transfer, giving the chance to the charge (air of mixture) to escape...


Thanks
Manolis Pattakos

Hi Manolis,

Another way of dealing with such concerns could be with a horizontal-3D semi dome shaped rotary valve seated above,
& opening a port directly into the combustion chamber, delivering a timed pressure charged swirl/vortex input..

& once the piston had swept up past the exhaust port.. after the cylinder had duly accepted the sonic pulse from its tuned exhaust chamber, ( any turbo being situated downstream from the pulse chamber).
A variable-tuned sonic nozzle-type exhaust could function as the 'throttle'.. along with variable pulsed fuel injection .

Perhaps visualized as similar to the diagram shown here: https://www.pureburnengines.co.uk/two-s ... pplication
but with the added 'active' valving on inlet & exhaust which predicate flow control.

This would also allow the choice of a typical crankcase scavenged 2T, plus turbo, -for smaller units.
.. or a '4T type' plain-bearing bottom-end with compound compressor/turbo - for larger machines..

[gruntguru]

Referring to Manolis Asymmetrical put timings.

The following durations have been identified from quoted timings;

115 Inlet
90 Conventional xfr
110 Asymmetric xfr
130 Exhaust

Quoting port and transfer timings without volumes and ducting geometry that will likely be backing them up does not fully describe the system.

How can someone asses and comment on it.

Who cares? The timing values are not the invention.

Koenigsegg (eg) invents a computer-controlled valve system. If they then publish some suggested valve timings, do we rubbish their invention because those timings don't make sense?

Koenigsegg valve system isn't fixed timing, just an actuation system. So not really relevant.

Oh dear!