2 stroke thread (with occasional F1 relevance!)

[manolis]

Hello all.


PatCVT

In the PatCVT a sprocket or gearwheel (actually an idler) is intermeshed with "teeth" on both spans of the V-belt.
The displacement of the center of the sprocket varies positively the transmission ratio:



enabling various "modes" of operation:

Drive Mode:
The lever that holds the sprocket is released to pivot freely about the cross; the CVT runs automatically under the control of a variator in the one conical pulley and of a spring / torque cam in the other conical pulley.

Sport Mode:
Performance oriented.
A control spring pushes the lever towards the conical pulley with the spring / torque cam; the CVT continues to run "fully automatic", but it selects shorter transmission ratios.

Economy Mode:
For green, quiet, reliable, comfortable operation.
The control spring pushes the lever towards the variator's conical pulley; the CVT continues to run "fully automatic" (as in the "Drive Mode"), but it selects longer transmission ratios.

Manual Mode:
The rider / driver displaces "manually" the lever about the cross to select any transmission ratio from the available infinity, regardless of what the "variator / spring / torque cam" command.
By locking the lever at a number of discrete positions, the CVT replicates a manual gear box.


In all modes the sprocket acts as a "baffle roller" (drive belt tensioner), too.

The available space inside the CVT of many scooters (like, for instance, the Sport-City Aprilia 250cc, below) is more than what the PatCVT needs:




How it works?

With the sprocket engaged with the toothed-V-belt as in the animation, the sprocket divides the V-belt in two parts (one at left of the sprocket and another at right of the sprocket), with each part maintaining its length constant.

The move away of the center of the sprocket from the one conical pulley causes the decrease of the effective diameter the V-belt is running on this conical pulley, and the increase of the effective diameter the V-belt is running on the other conical pulley.



For more: http://www.pattakon.com/pattakonPatCVT.htm


Thoughts?

Thanks
Manolis Pattakos

[Tommy Cookers]

at this moment I seem to need convincing that the argument below is incorrect (and how/why it is incorrect) .......

in the PatBox the controlling belt has rather small losses (that might be smaller again if it was eg a metal band)
in the PatCVT the controlling belt has loads passing through its teeth via the pulley teeth ? (the belt teeth you have said before are not intended for loads)
because the belt load path on the other side of the control point is 'length-compliant' (not rigid as in the PatBox)

so the controlling losses seem to be higher in the PatCVT

what can the PatCVT do that couldn't be done by controlling belt effective length/tension with an external tensioner ? (eg roller on back side of belt)
ie is its benefit entirely its compact latout ?

and the question (of whether losses are greater than in conventional systems of external CVT control) is still open ?

it might be argued that the Pat CVT is an enabler of the 2 stroke 'daily driver'

[manolis]

Hello Tommy Cookers.

You write:
“in the PatCVT the controlling belt has loads passing through its teeth via the pulley teeth ? (the belt teeth you have said before are not intended for loads)
because the belt load path on the other side of the control point is 'length-compliant' (not rigid as in the PatBox)”


In the PatCVT there is no “controlling belt”.
There is only one belt, the V-belt, that has teeth at its inner side.



The controller is the sprocket intermeshed with teeth on both spans of the V-belt.


Regarding the efficiency:

Take a scooter CVT, like, say, the SprotCity Aprilia 250cc of the photo, modified to PatCVT.

If you release the lever that holds the controlling sprocket, the bearing of the sprocket runs, more or less, unloaded; the teeth of the sprocket remain unloaded, too.
The sprocket acts as the original “baffle” roller.
The efficiency of the CVT is as without the PatCVT.

Now suppose that at some conditions you prefer a 15% shorter, or longer, transmission ratio than the ratio the CVT selects normally at these conditions.
The bearing of the sprocket and its teeth are far from being overloaded, because the sprocket has to apply to the V-belt only the difference of the force required for the specific transmission ratio, and because the efficiency of a toothed sprocket cooperating with a toothed belt is quite high (above 99%; worth to note: there is only one sprocket).

For instance, suppose a force of 20Kp (44lb) is applied on the center of the sprocket towards the one conical pulley; this force changes by 10Kp (22lb) the force acting on each span of the V-belt; and due to the wedge action of the conical pulley, this force (the 20Kp / 44lb) is multiplied by 4 to give the additional axial force resulting on the moving half of each conical pulley.
So, with 20Kp loading the roller bearing of the sprocket, and 10Kp force from the sprocket on each span of the V-belt, the axial force on the movable halve of each conical pulleys change by 80Kp (176 lb).

If something of the previous is confusing, please let me know to further explain.



You also write:
“what can the PatCVT do that couldn't be done by controlling belt effective length/tension with an external tensioner ? (eg roller on back side of belt)
ie is its benefit entirely its compact latout ?”

Any drawing?
I can’t get what you mean.

Thanks
Manolis Pattakos

[Tommy Cookers]

you say .....
'the sprocket has to apply to the V belt only the difference in the forces'

I think losses will be produced by belt/sprocket action associated with each of the forces
ie proportionate to the algebraic sum of the forces not the difference in forces

[manolis]

Hello Tommy Cookers.

You write:
“I think losses will be produced by belt/sprocket action associated with each of the forces
ie proportionate to the algebraic sum of the forces not the difference in forces”


Let’s take the marginal case wherein the lever of the sprocket is released to move freely.

The force between the sprocket and each span of the V-belt is near zero.
The force on the bearing of the sprocket is small, too.
These make the losses “produced by the belt/sprocket action” actually zero.

Obviously the strong force that loads the V-belt (through this force the one conical pulley transmits power to the other conical pulley) does not affect the above, almost zero, friction losses.

Do I miss something?

Thanks
Manolis Pattakos

[Tommy Cookers]

since you ask, I find myself saying that you are missing a response to my point
and you are pre-emptively trivialising the loss aspect of the forces developed at the belt/control pulley contact region

however I wish your designs success in their widening of the scope of inexpensive properly controlled CVTs

[Muniix]

I say again manolis, make one and show us. pretty pictures mean nothing.

Watch out, you'll get your posts deleted, but the credibility you gain from the likes of the designer of the McLaren P1, Engineers from Audi, FCA, BMW, ... is worth it.

[Muniix]

The crankshaft rotating assembly in the PATop design has excessive bearing friction and inertial forces due to having bigger big end diameter than main journals.

You don't need to perform a bearing friction model simulation to realise this.

You have excessive mass in the bigends meaning the smaller mains are under greater loads than they need be. Flexing the crankshaft more than it need to.

This is just bad engineering, what goal is this design trying to achieve, technical analysis only arrives at short man syndrome.

When someone does identify an issue it's never acknowledged or worse the classic deflection, straw man response follows. With the identified issue ignored and the original claim repeated all over the interwebs, confirming the analysis is correct, SMS.

Hello Uniflow.


You write:
“I say again manolis, make one and show us. pretty pictures mean nothing.”


However,
the meaning of a technical discussion like this one,
is by far different than:
“make one and show us”.


Someone proposes a new (or “new”) technical solution; the rest forum members can read, understand (the “pretty pictures” mean a lot in this stage) and think.

Then, if they like so, they write down their justified (or not) technical objections / thoughts.

It is a “win-win” process.


The guy who proposes the new, or “new”, technical solution is asking for “independent third party” objections and opinions in order to decide either to abandon the idea, or to proceed with it (by making prototypes, by testing them etc).

He is also presenting his idea to “whom it may concern”.




By the way:

Seven months ago, at page 87, posts #1296-1297, a discussion remained unfinished, even if the “make one and show us” was the case:


The PatOP pattakon engine is real:

http://www.pattakon.com/patop/PatOP1_mov.jpg

from metal:

http://www.pattakon.com/patop/PatOPpro6.jpg

http://www.pattakon.com/patop/PatOPpro2.jpg

works on Diesel fuel:

(youtube video: https://www.youtube.com/watch?v=2ByEgfTTq1I )

and concentrates unique characteristics:

Bore: 79.5mm
Stroke: 64+64=128mm
Displacement: 635cc
Compression ratio: 17
Scavenging pump bore: 130mm (1.34 scavenging ratio)
Total engine height: 500mm
Total engine weight (without the flywheel): less than 20Kp

It is an:
opposed-piston,
two-stroke,
single-cylinder,
single-crankshaft,
full-balanced (vibration free),
cross-head,
direct-injection Diesel engine,
with built-in "volumetric" (for a wider rev range and flat torque curve) scavenging pump,
with four-stroke-like lubrication,
and with some 35% as compared to the conventional, or some 20% as compared to the Junkers-Doxford and to the OPOC of EcoMotors, additional time for the injection and combustion of the fuel.


It is also patented,
which means that some experts / specialists in the field (examiners in big patent offices like the USPTO, the UK-IPO etc), after searching all the prior art, they decided the idea in question is new, it has inventive step and is industrially applicable.


Worth to mention here:

The only things from the market used in the above PatOP prototype engine are the piston rings (from a VW TDi), the plain bearings (from a BMW 1600cc) and the fuel injection system (it is from a cheap Chinese 4-stroke electric generator).
All the rest parts were made either from 7075 aluminum billet (if I remember correctly, we started with 54Kg (120lb) aluminum for the casing) or from Orvar Supreme steel (crankshaft, connecting rods).


Enjoy how nice, smoothly and clearly it runs on Diesel fuel, standing free on a desk. We talk for big single-cylinder direct injection Diesel engine.

The prototype works as the theory predicts.

However, the important is the theory, the theoretical solution proposed; not the working prototype.

Please do read, at the page 107, post #1601 of this thread, what the professor Rui Chen of the famous Loughborough University - UK did (“Quasi-constant volume spark ignition combustion”, presentation in the International Engine Expo 2009, Stuttgart Germany) in order to achieve the longer piston dwell of the OPRE and PatOP engines.


So, if you still don’t like to comment on the PatATE idea because the “make one and show us” requirement is not yet fulfilled,
you can alternatively write your technical objections / thoughts about the PatOP.

Thanks
Manolis Pattakos

[gruntguru]

The crankshaft rotating assembly in the PATop design has excessive bearing friction and inertial forces due to having bigger big end diameter than main journals.

You don't need to perform a bearing friction model simulation to realise this.

You have excessive mass in the bigends meaning the smaller mains are under greater loads than they need be. Flexing the crankshaft more than it need to.

This is just bad engineering, what goal is this design trying to achieve, technical analysis only arrives at short man syndrome.

When someone does identify an issue it's never acknowledged or worse the classic deflection, straw man response follows. With the identified issue ignored and the original claim repeated all over the interwebs, confirming the analysis is correct, SMS.

Muniix, sometimes you demonstrate a high level of understanding of engine technology but you repeatedly cancel such moments with one-eyed posts like this.

- Bearing friction? Seriously? Take a look at the OPOC.http://thekneeslider.com/ecomotors-team ... oc-engine/
Do you have any idea of the contribution of crankshaft bearing friction to engine losses? 100% increase in big end bearing friction would make a tiny difference - easy to justify if there are significant gains elsewhere.

- Main bearing loading? Seriously? The Pat OP has zero loading of the the main bearings - from combustion forces and inertial forces. They all cancel.

[FW17]

Maybe already posted

https://www.researchgate.net/publicatio ... -Expansion

[Pinger]

Maybe already posted

Not that I've seen... so thanks for posting.
Haven't (yet) read the whole paper but it is certainly more elegant than the effort (trapping valve) from Lotus and reminiscent of a Subaru proposal from several decades back (though I noticed the paper references earlier 'valves').
Not convinced external control is the way forwards. I'm looking at an internally valved design (but without the additional friction surface a sleeve valve presents) but too early to say it will work as I hope. More later (assuming I pursue it and make it in metal).

[Muniix]

I did say specifically the PATio engine, one with the one piece rods, larger bigends than mains.

The crankshaft rotating assembly in the PATop design has excessive bearing friction and inertial forces due to having bigger big end diameter than main journals.

You don't need to perform a bearing friction model simulation to realise this.

You have excessive mass in the bigends meaning the smaller mains are under greater loads than they need be. Flexing the crankshaft more than it need to.

This is just bad engineering, what goal is this design trying to achieve, technical analysis only arrives at short man syndrome.

When someone does identify an issue it's never acknowledged or worse the classic deflection, straw man response follows. With the identified issue ignored and the original claim repeated all over the interwebs, confirming the analysis is correct, SMS.

Muniix, sometimes you demonstrate a high level of understanding of engine technology but you repeatedly cancel such moments with one-eyed posts like this.

- Bearing friction? Seriously? Take a look at the OPOC.http://thekneeslider.com/ecomotors-team ... oc-engine/
Do you have any idea of the contribution of crankshaft bearing friction to engine losses? 100% increase in big end bearing friction would make a tiny difference - easy to justify if there are significant gains elsewhere.

- Main bearing loading? Seriously? The Pat OP has zero loading of the the main bearings - from combustion forces and inertial forces. They all cancel.

[J.A.W.]

Kevin Cameron article suggests KTM could sell its new TPI 2T's in road-legal format, stateside:

http://www.cycleworld.com/ktm-transfer- ... for-street

IMO, a logical next step for KTM, ought to be - that 2T TPI engine - in a dedicated roadbike chassis.

[manolis]

Hello J.A.W.

Here is my comment just added to Kevin Cameron article:


Hello.

Quote from the dirt-bike-rider:

“Also KTM had problems with euro 4 and some KTM dealers can’t anymore sell 2017 models in their country’s. But new 2018model will come with euro 4 and it will easy pass euro 4 with elections fuel injection and lower emissions. But there is new problem for KTM, in 2020 we will have new big problem called euro5. But we all hope KTM will find solution for this and make EXC and XC models legal for street.”


According the euro5 regulations (in force from 2020) it is required a 60% further reduction of the Hydrocarbons (0.10gr/Km instead of the 0.17gr/Km allowed by euro4).

Reasonably the KTM EXC 250/300 TPI cannot comply with the euro5 emission regulations without a significant reduction of their power output.

With the exhaust port remaining open for several crankshaft degrees after the end of the transfer (isn’t this what the KTM is doing?), what stops the fuel (already entered into the cylinder) from escaping to the exhaust?

For greener (euro5) and powerful at the same time 2-strokes, the exhaust must close before the transfer. Substantially.

How?

Take a look at the patented PatATi design and prototype at http://www.pattakon.com/pattakonPatAT.htm , and then at the PatATE 2-stroke design at http://www.pattakon.com/pattakonPatATE.htm

Thanks
Manolis Pattakos

[J.A.W.]

As an example of the inherent attributes of the 2T as a road race machine (where not banned, of course):

http://www.iomtt.com/News/2017/08/26/An ... -Race.aspx

Ironic for Honda that it was one of their 2T's - after their embarrassing F1 & Moto GP 4T DNF's - last W/end..

I note that Bruce Anstey has qualified at No1, for the Classic Superbike race - on a 500cc 2T, as well.