2 stroke thread (with occasional F1 relevance!)

[gruntguru]

Tommy if you look closely at the torque plots provided you will see that the Panigale 1299 has between 108 and 144 Nm across the entire rev band shown (4k -11k rpm). That is not a "peaky" engine.

[Tommy Cookers]

the torque falls from 4000 to 5500 rpm - this fall is surely an indisputable manifestation of 'peakiness' ?

for road driving we need a torque curve consistently rising or flat (at least not falling) over most of the speed range
because only this will allow a consistent response to the right foot action (or inaction) that we call driving
eg where hills and/or headwinds appear, the right foot demands an instant and seamless torque increase

we might by borrowing an aviation analogy see this consistent torque curve as essential to 'speed stability'
the traditional rising torque curve at the low speeds and falling torque curve at the higher speeds giving easier and better control of speed
speed stability is artificially enhanced eg in airliners by automatic thrust control on landing approaches, as is apparent on windy days

even a CVT would without intelligence be less than satisfactory dealing with an inconsistent torque curve
though the undesirable driven pulley over-clamping in the simple CVT helps to stabilise its behaviour and so satisfy the user
improving the simple CVT is not easy for this reason

[Pinger]

is the given valve timing correct ? (ie is it run timing not eg values at a special large valve clearance for timing definition only ?)
because the declared overlap of 30 deg or 38 deg seems far too small for such a very high performance engine spec

Laboratory figures TC. On-road figures will be higher. That's VAG ownership for you....

[Pinger]

for road driving we need a torque curve consistently rising or flat (at least not falling) over most of the speed range
because only this will allow a consistent response to the right foot action (or inaction) that we call driving
eg where hills and/or headwinds appear, the right foot demands an instant and seamless torque increase

we might by borrowing an aviation analogy see this consistent torque curve as essential to 'speed stability'
the traditional rising torque curve at the low speeds and falling torque curve at the higher speeds giving easier and better control of speed

The quest for fuel efficiency removes any desire to run beyond the speed of Tmax (providing the 'torque back-up' that used to make for 'flexibility') with 4Ts. Thus the flexibility has to be with the transmission's keenness to drop ratios in response to demands from a driver's right foot.
As I've alluded to before, the 2T's lack of sensitivity to throttling losses can provide what you seek without a fuel consumption penalty.

even a CVT would without intelligence be less than satisfactory dealing with an inconsistent torque curve
though the undesirable driven pulley over-clamping in the simple CVT helps to stabilise its behaviour and so satisfy the user
improving the simple CVT is not easy for this reason

I'm not convinced passive CVTs do actually suffer from driven pulley over-clamping, that particular issue being put to bed with the advent of torque sensitive driven pulleys.
What is obvious though is that the efficiency peaks at the 1:1 ratio - where the keen eye will observe that the radius of each sheave (as the belt sees it) is identical. It is moving to lower or higher ratios and incurring a smaller radius on one sheave and thus forcing more bending on the belt that drops the efficiency. Until the evidence appears to support over clamping as the the cause, I'll run with the above as the true cause of inefficiency in the higher ratios.

[uniflow]

I give up, he who shouts loudest wins, even if it was black, manolis would argue it was white, just for arguments sake.
KTM are NOT using a Rotax patent, just have a look at the patent yourself, if you can't see then perhaps new glasses might be in order. KTM are using this Kiwi TPI system because they DON'T have to pay anyone for the patent, they found it free off the internet, saw how well it worked then used it, good on them.
The second cylinder that was developed by KTM WAS the rotax patent, first being the Orbital system, this the third development is a copy of my YZ system.
For those that may not believe me, not long after we shot the youtube video of the YZ running around my yard (that would be in real running hardware), Kiwi Rider magazine did an article on this TPI system in both the F9 Kawasaki and the YZ. The guy that wrote the article used to work at KTM Austria and sent Kiwi Rider magazines back to his friends at KTM for coffee table reading. This Kiwi TPI development was handed to them, the KTM development team were able to read about it at lunch time ( I explained the system fully in the article), finally for KTM a workable answer AND they didn't have to pay anyone royalties, a win for KTM I say.
But keep on believing what you want.

[gruntguru]

I'm not convinced passive CVTs do actually suffer from driven pulley over-clamping, that particular issue being put to bed with the advent of torque sensitive driven pulleys.
What is obvious though is that the efficiency peaks at the 1:1 ratio - where the keen eye will observe that the radius of each sheave (as the belt sees it) is identical. It is moving to lower or higher ratios and incurring a smaller radius on one sheave and thus forcing more bending on the belt that drops the efficiency. Until the evidence appears to support over clamping as the the cause, I'll run with the above as the true cause of inefficiency in the higher ratios.

I think Manolis' claims of over-clamping as a cause of friction relate to the "cheap" moped CVT market.

[manolis]

Hello Uniflow.

Several pages ago you had asked what differs the OPRE / PatOP from the other Opposed Piston engines.

This is exactly what a patent is for:

A patent is an official document wherein they are defined the differences of a new idea from the prior art, and the advantages these differences brink to the art.


The patent examiners have the authority and the duty to search, examine and decide whether the idea in question is really new and patentable.
Nobody else has such authority.
If required, the patent examiners ask the inventor /applicant to limit his invention in order what is left, to be really his intellectual property.

This is how things work.

You can’t claim intellectual property over an idea / invention in the US without applying from a patent in the US-PTO and without a patent to be eventually granted for the specific idea / invention.

Only after the granting of a patent the inventor can claim that this, or that, is his own idea / property.


And it costs way less than making a good quality working prototype.


To put it in numbers:

Here are the fees paid so far for the PatEf:



In a few months the UK_IPO will respond by the list of the most relevant patents they will find with their search.

Then, we will decide to proceed with the substantive examination, too (the additional cost of 80 UK pounds makes the total cost for taking the UK patent: 230 UK pounds, or US300$), or to withdraw the patent.


Are the 150 pounds too much?

Shouldn’t you apply for a patent before making your TPI engine prototype?

What can you do now to support that the TPI is yours and not of KTM or of Rotax?


On the other hand, applying for a patent is not so simple.
It means that you can define the differences of your idea from the hundreds of the TPI patents mentioned by the examiner in the TPI patent granted to Rotax some 17 years ago (previous post).


So, what are the differences of your TPI?

What makes it unique among the other TPI’s proposed so far?

To put it differently:
If Rotax asks you to pay royalties (or asks you to stop using your prototype), have you strong arguments to refuse?


As I wrote again, this is the way things work in the “intellectual property” field.

Even if you don’t like the previous "teaching", it may prove useful and profitable (in the long term) for some guy who is silently reading this forum and is having a project in mind.

The advice is simple and general: "apply for a patent first, and then reveal your idea".



By the way:
I know that I know nothing about engines.
This is why I asked the others, who think they know, to spot on the mistakes / tricks of my simpleminded approach about the PatATE operation based on the inertia of the working gas.
I am still waiting.



PS.
What would be the estimated cost for manufacturing a PatATE prototype?
E-mail me.

Thanks
Manolis Pattakos

[manolis]

Hello Pinger.

You write:
“What is obvious though is that the efficiency peaks at the 1:1 ratio - where the keen eye will observe that the radius of each sheave (as the belt sees it) is identical. It is moving to lower or higher ratios and incurring a smaller radius on one sheave and thus forcing more bending on the belt that drops the efficiency. Until the evidence appears to support over clamping as the the cause, I'll run with the above as the true cause of inefficiency in the higher ratios.”



This plot:



was made based on the data provided in the publication:
http://www.pattakon.com/PatBox/SECVT.pdf
of the:
Eindhoven University of Technology
Department Mechanical Engineering
Dynamics and Control Technology Group

The above plot concerns the most expensive (and technologically advanced) CVT for scooters: the SECVT of the Suzuki Burgman 650 and of the Aprilia Mana 850 (made/used under the license of Suzuki).

As you can see, at the medium transmission ratios (red curve, 1:1 ratio: the radiuses the V-belt runs on the two pulleys are, more or less, equal) the efficiency is not higher than at the lower transmission ratios (cyan curve) wherein happens “more bending on the belt that drops the efficiency.”

The efficiency is about the same (red curve and cyan curve) at the heavier loads, while at the lighter loads the CVT is substantially more efficient at the lower transmission ratios.

In the longer transmission ratios (blue curve) the CVT operates inefficiently.


Let’s put it in numbers to see what “inefficiently” means:

The Suzuki Burgman 650 makes 55hp at 7,000rpm, and 62mN at 5,000rpm (which means, at 5,000rpm it makes 44hp).

For “highway cruising” (say 100Km/h, lever road, no opposite wind) it needs no more than 10hp of power (a medium size car needs around 15hp), and the transmission ratio cannot help being near the longest possible.

According the above plot, the efficiency of the SE-CVT of Burgman at cruising is somewhere between 80% and 85% (far below the 95% peak efficiency), which means the scooter consumes some 10-15% more fuel.
For the 10hp the CVT passes to the rear wheel at cruising, another 1.5hp is consumed inside the CVT as friction overheating the V-belt compartment and wearing the V-belt.


Now, take another look at the PatEf.

The PatEf simply unloads the V-belt CVT (of all scooters and sleds, expensive or not) from a significant part of the unnecessary clamping (and friction, and wear it causes), without any risk of belt slippage.



As it is now, the most expensive scooter CVT (the SECVT) operates at cruising not at the FLA point (above plot), but with three times heavier clamping of the V-belt (top right point).

Thanks
Manolis Pattakos

[Tommy Cookers]

what I called driven pulley over-clamping seems to degrade transmission % (power?) efficiency by the effect of excessive belt tension ......
when the drive pulley is at a large diameter so there's a lot of belt length in contact

but the power loss/belt heating is no greater at these low efficiencies than at the high efficiency end (because that's high power)

reduced clamping will best benefit fuel consumption only where in cruise the engine is unthrottled or slightly throttled
so might be considered an alternative to a conventional design of greater ratio range and bulk ?

to self - I notice that modern car CVTs are rigged to give some rpm rise with roadspeed (presumably to match buyer prejudice)

[manolis]

Hello Tommy Cookers

You write:
“but the power loss/belt heating is no greater at these low efficiencies than at the high efficiency end (because that's high power)”


You are right.

And this means that:

If with 20kW power provided by the drive shaft, the CVT “eats” the 1kW in friction / wear and delivers the rest 19kW to the driven shaft,

and if with 5kW power provided by the drive shaft, the CVT “eats” again 1kW in friction / wear and delivers the rest 4kW to the driven shaft,

then

in the first case the efficiency is 95%,

while In the second case the efficiency drops to 80%.




From another viewpoint:


Take the (coloured) plot showing the SECVT efficiency versus the load.

With the PatEf the over-clamping drops substantially at the longer transmission ratios, it drops at the medium transmission ratios, and it remains the same at the lower transmission ratios,

So, the cyan curve (efficiency at the lower transmission ratios) remains unchanged.

But the other two curves change.

According the theory behind the PatEf:

the red curve (efficiency at the medium transmission ratios) will shift upwards, above the cyan curve for all loads, remaining above, say, 96% from 60% load to 100% load,

while the blue curve (efficiency at the longer transmission ratios) will shift substantially upwards, at or above the cyan curve for all loads, remaining above 95% along the heavier load range,

say, like:



If the above are correct, the CVT (of scooters, sleds, bicycles etc) “plays” as equal with the conventional gear-boxes as regards the efficiency, being undoubtedly superior as regards the easy handling / user friendly.

Thanks
Manolis Pattakos

[gruntguru]

but the power loss/belt heating is no greater at these low efficiencies than at the high efficiency end (because that's high power)

reduced clamping will best benefit fuel consumption only where in cruise the engine is unthrottled or slightly throttled
so might be considered an alternative to a conventional design of greater ratio range and bulk ?

and since real world vehicles spend most of their time at part throttle, gains in this mode will have the most effect on overall fuel economy.

[Pinger]

By the way:
I know that I know nothing about engines.
This is why I asked the others, who think they know, to spot on the mistakes / tricks of my simpleminded approach about the PatATE operation based on the inertia of the working gas.
I am still waiting.

IC engines are far too nuanced in their operation Manolis for that approach to work. Read The High Speed Combustion Engine by Sir Harry Ricardo (periodically reprinted, possibly available as 'net download, expensive second hand) and give yourself a grounding in the essentials. You bring fresh thinking but the practicalities need to be understood as a whole. THSCE can provide you with this. From there, who knows what you may come up with.

[Tommy Cookers]

reducing transmission power loss by eg 10% of engine power ......

will only reduce fuel consumption by 10% if bte does not fall with the corresponding reduction in engine power demanded
bte will fall with reduced power due to increased throttling
and eg if bte falls by 10% of 'original' bte then there will be no fuel consumption benefit (likely with high power engines)

so the benefits of a reduced transmission loss would not be strong at these very high ratios


regarding the benefits of very high ratios........
the 2-wheeler seems to benefit little from these (unlike the 4-wheeler)
of course the inherently seamless 'automatic' behaviour is a boon even with a manual-conventional ratio range
(remember, Honda and Suzuki once made torque converter 'auto' (2 speed 'manual' footshift) motorbikes)

the prime benefit to an automatic car is reduced engine noise etc, with some economy improvement (the clamping load is managed with lavish devices)
car CVTs max ratio is eg 160% of the ratio for max neutral-condition speed

there's little noise benefit (to the rider) with a 2-wheeler and (imo as above) little economy benefit
anyway the CVT (especially the simple CVT) is smaller etc and works better without great ratio range
works better eg in the more practical response throttling up/clutching up and throttling down ie some natural 'engine braking' (with 4 strokes)
with the larger-engined machines the use of manual gear selection in traffic etc may be preferred for response reasons

I now wonder (having found a lot of interesting but rather user-oriented info) .....
what max gear ratio % do 2-wheeler CVTs actually use ?
what reduction in over-clamping is obtained from mechanical torque-sensitive driven pulleys ?

[Pinger]

what reduction in over-clamping is obtained from mechanical torque-sensitive driven pulleys ? (I wonder)

Relying on memory as opposed to digging out my Aaen book.... sufficient to stop shredding belts at low power outputs. Again from memory, I think the limit was circa 30hp without the belt being destroyed in short order. The Aaen book has the details.

[gruntguru]

reducing transmission power loss by eg 10% of engine power ......

will only reduce fuel consumption by 10% if bte does not fall with the corresponding reduction in engine power demanded, bte will fall with reduced power due to increased throttling and eg if bte falls by 10% of 'original' bte then there will be no fuel consumption benefit (likely with high power engines)

Unlikely. Your general point is correct but for zero consumption benefit you need the following scenario
1. at constant speed, a reduction in belt tension reduces load on the engine by say 10%
2. operator must reduce throttle to reduce output by 10% to maintain speed
3. the reduction in throttle setting results in no reduction in fuel rate?????