2 stroke thread (with occasional F1 relevance!)

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello Tommy Cookers.

You write:
“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)”



On this reasoning, we should put a “disk brake” on the one pulley of the CVT to add lots of friction which will enforce the engine to operate permanently at wide open throttle, and so higher efficiency.


Or, think it differently:
Saving the 10% of the power of the engine which is consumed as friction in the CVT, a 10% smaller engine can be used: same performance, 10% higher mileage.


Or think it more differently:
The PatEf CVT with 10% lower friction can be tuned to keep the engine at lower revs, wherein for the same power it is required more open throttle.



The basic characteristic of the CVT’s is their automatic operation.


Another characteristic is their ability to keep the engine at the desirable revs for a wide range of vehicle speeds:

Image

which is not possible with the conventional gear boxes:

Image


Another characteristic is the smooth “gear-shifting” (the guy who made the first PatBox prototype wrote, when he first tested it: it shifts like butter).


Another characteristic is the continuous change of the transmission ratio from the shortest to the longest allowable value.


Another characteristic of the scooter and sled V-belt CVT’s is that they are “uncontrolled”.

The SECVT of Suzuki:

Image

the PatBox CVT:

Image

and the PatCVT:

Image

offer control (automatic or manual) over the transmission ratio of the CVT, keeping at the same time its “full automatic” characteristic when the driver / rider likes so.


Another characteristic of the scooter / sled CVT’s is the excessive fiction loss due to the over-clamping of the V-belt, which reduces the mileage and worsen the performance (a motorcycle having the same engine and the same weight with a scooter, is faster, has higher top speed and consumes less fuel).

The PatEf:

Image

is a simple way to reduce substantially the friction and use the power of the engine for pushing the vehicle forwards and not for overheating the CVT compartment and for wearing the drive belt.


Reasonably,
a “controllable” (PatBox?) automatic CVT having the same efficiency (PatEf) with the manual gear-boxes:

Image

seems preferable for most applications (motorcycles, small cars, scooters, sleds, ATV’s, bicycles etc).

***Worth to note: the % load in the above plot refers to the CVT and not to the engine.



You also write:
"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 ?"


These data, and many more, can be found in the http://www.pattakon.com/PatBox/SECVT.pdf

Thanks
Manolis Pattakos

Tommy Cookers
617
Joined: 17 Feb 2012, 16:55

Re: 2 stroke thread (with occasional F1 relevance!)

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at idle the bsfc is infinite
at some power just above idle the bsfc is very poor
just above that power the bsfc is poor
etc

so at low powers replacing a reduced transmission loss with a reduced engine power degrades bsfc such that fuel saving is pointlessly small
here's a fuller than usual bsfc map (No 14 - a Toyota V6) that clearly supports that
http://ecomodder.com/wiki/index.php/Bra ... BSFC)_Maps
bsfc is c.250 gm @ c. 1700 rpm WOT
bsfc is c.500 gm @ c. 1700 rpm throttled to c. 22 mN torque
we can plausibly infer bsfc is c. 550 gm @ c. 1700 rpm throttled to c. 20 mN torque (replacing your 10% power saved by the transmission)
22 mN @ 500 gm bsfc and 20 mN @ 550 gm bsfc have identical fuel consumption rates
plausibly infer as the rate of bsfc degradation with torque reduction is shown in the map to increase greatly at small torques
degraded from increases in pumping losses and thermodynamic losses due to lower relative compression and from relatively higher friction etc

(imagine eg we have a Burgman or Aprilia type machine powered by 2 cylinders from the above Toyota V6) ......
if we lower the power enough ie to urban speed limits there is little or no fuel saving potential
this should not be news to anyone - it's the same reason that economy does not for ever increase with speed reduction in conventional vehicles
yes, at higher powers there will be some fuel saving - and I never have said otherwise

this effect is greater with motorcycles than with cars because of the difference at low speeds in aero and mechanical drag relative to engine power
the 650 Burgman has a ratio spread c. 4x - and a similarly-engined conventional Kawasaki motorcycle has a spread of c. 3.2x
a car CVT has a ratio spread of c. 6x, though even this has been claimed insufficient eg by advocates of Perbury type CVTs
the CVT car having a greater proportion of its engine power in use at legal cruising speeds (than the motorcycle) has more economy benefit
and low rpm corresponding to high ratio spread may be mechanically disadvantageous to the transmission of the Burgman type vehicle
the 2 stroke twin or 3 cylinder engine would be better in this respect

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello Tommy Cookers


Based on the "CVT efficiency" plot for the SECVT of Suzuki:

Image

the bsfc plot of the Toyota V6 of your link:

Image

has been modified as follows:

Image

Besides the rpm, the horizontal axis is now used to show the efficiency of the CVT, too.

The blue horizontal lines give the CVT efficiency at the longest transmission ratio for various loads (100%, 50%, 25%, 10%).

Similarly, the red and cyan horizontal lines give the CVT efficiency at various loads for the medium and the shortest transmission ratios respectivelly.


At your reference point:

20 mN @ 1,700rpm @ 550 g/kWh

the engine provides only 4% of its peak power (and works at a 15% BTE (Break Thermal Efficiency)), while the CVT operates at an efficiency of about 20%.

The overall efficiency of the power train (comprising the engine and the CVT) is 0.15*0.2=0.03=3%.


_____________________________________________________________________________


An example:
It is like having an elephant weighing five tons and capable for carrying 1,000Kg of load, and using it for carrying 75Kg load: the process gets quite inefficient (waste of resources).


On the other hand, and according the above plot:

The peak efficiency of the set "engine-CVT" is 31%.
The above 31% peak overall efficiency happens in the area 80% to 90% load and with the engine operating between 2,000-2,500rpm; in this area the engine efficiency is 34% and the CVT efficiency is no less than 90%.

The overall efficiency (engine and CVT) remains above 24% for the whole area above the 50% load.

The overall efficiency (engine and CVT) remains above 15% for the whole area above the 25% load.



By the way, according the Aprilia, the engine of the Aprilia 850 Mana:

Image

which is a "hybrid" between motorcycles and scooters (it uses a version of the SECVT of Suzuki):

Image

makes 76hp.

The Sukuzi Electronically controlled CVT of the Aprilia Mana 850 can operate completely automatic (scooter like), but it can also operate like a serial 7-ratios gearbox (motorcycle like).


Quote from http://www.motorcycle-usa.com/2009/02/a ... 50-review/ :

"The liquid-cooled 839cc Twin may not be the earth-trembling torque monster of its Italian brethren, but sticking the Mana in fourth ‘gear’ it spun the Mickey Cohen Motorsports dyno up to 54 hp and 39 lb-ft torque.:

Image

End of Quote


If Aprilia is correct for the 76hp the engine can make, and if the above dyno is correct, too, then 22hp (i.e. the 22/76=29% of the peak power) are lost as friction in the power train (engine to CVT to final transmission to tire to road).

Burning to friction 22hp is not simple, at all.
Just think of the cooling / ventilation required in the CVT compartment to avoid overheating.


Thanks
Manolis Pattaos

Muniix
14
Joined: 29 Nov 2016, 13:29
Location: Sydney, Australia

Re: 2 stroke thread (with occasional F1 relevance!)

Post

manolis wrote:
14 Sep 2017, 05:43
Hello Tommy Cookers.

You write:
“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)”

On this reasoning, we should put a “disk brake” on the one pulley of the CVT to add lots of friction which will enforce the engine to operate permanently at wide open throttle, and so higher efficiency.

Or, think it differently:
Saving the 10% of the power of the engine which is consumed as friction in the CVT, a 10% smaller engine can be used: same performance, 10% higher mileage.

Thanks
Manolis Pattakos
Only if your putting that 'brake' energy into energy storage to be used by electric motor, this is the strategy of the Hybrid engine management! Some people's logic, just insane!

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello all.

Ιn a bicycle:

the front sprocket is replaced by the conical pulley 2,
the rear sprocket is replaced by the conical pulley 4,
the chain is replaced by a constant-length V-belt 5,
the pedals are secured on the shaft 1,
the rear wheel is secured on the shaft 3 :

Image

With the V-belt having a constant length of 1500mm,
and a 500mm centre-to-centre distance between the two shafts 1 and 3,

the following plot shows the transmission ratio and the pairs of diameters the V-belt runs on the two pulleys:

Image


By the way, here are some animations added to the http://www.pattakon.com/pattakonPatEf.htm web page:

Image

Image

Image

The last two show that after the assembly the PatEf springs cannot disassemble.

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Forum member here Uniflow has his latest - in metal - 2T on test.. well done Neil.

https://www.youtube.com/watch?v=8IA3Xth6jXc
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

User avatar
Zynerji
111
Joined: 27 Jan 2016, 16:14

Re: 2 stroke thread (with occasional F1 relevance!)

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J.A.W. wrote:
09 Oct 2017, 08:45
Forum member here Uniflow has his latest - in metal - 2T on test.. well done Neil.

https://www.youtube.com/watch?v=8IA3Xth6jXc
Very well done!

Huge respect for anyone that ever moves an idea into reality!

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello all.

Congratulations to Neil Hintz for his 700 twin start up:



If the concept is the first step, the metal is the third step; good luck with the rest steps.

Thanks
Manolis Pattakos

uniflow
36
Joined: 26 Jul 2014, 10:41

Re: 2 stroke thread (with occasional F1 relevance!)

Post

This engine has flown before, just this is the new power valve cylinders with slightly higher exhaust port. I am so tempted to just add a gearbox housing to the pattern and cast up a MC version. These cylinders are also TPI capable with the lugs already cast in to the cylinders, it sounds nice, reminds me of an RZ350.

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

Post

uniflow wrote:
10 Oct 2017, 21:55
This engine has flown before, just this is the new power valve cylinders with slightly higher exhaust port. I am so tempted to just add a gearbox housing to the pattern and cast up a MC version. These cylinders are also TPI capable with the lugs already cast in to the cylinders, it sounds nice, reminds me of an RZ350.
Do it! Please..
I am sure that there'd be no shortage of chassis/gearbox donors lining up to be in on such a project..( inc' me).

Offer it to Dorna, as a Moto 2 engine package?
Or as a FSAE student-built car mill?

& it could even make for a wild superkart racing series..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).




denktank
1
Joined: 25 Apr 2015, 19:18

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Found this, don't know what too think off it

engine on gasoline vapors:
https://www.youtube.com/watch?v=iQt5AV3gNKw

Plasma reactor motor:
https://www.youtube.com/watch?v=d5YsK3bwzPM

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

Post

denktank wrote:
16 Oct 2017, 14:52
Found this, don't know what too think off it

engine on gasoline vapors:
https://www.youtube.com/watch?v=iQt5AV3gNKw

Plasma reactor motor:
https://www.youtube.com/watch?v=d5YsK3bwzPM

I think its off-topic, seeing as they are 4T's..

Though, interestingly enough, & coincidentally also concerning Muniix's recent sophisticated sensor control post on another thread..

..there is a current line of 2T research that is basing coordinated ignition timing/fuel injection events on sensor feedback..
..as cycled from the pressure-pulse/heat gradient values taken from the exhaust nozzle/expansion chamber..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

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