Pneumatic MotoGP

[imdying]

This should make for an interesting turn of events... http://uk.eurosport.yahoo.com/06072007/58/season-2007-yamaha-debut-new-engine.html

[xwhatsit]

They've been doing that in F1 for some time, haven't they?

Super mega high revving MotoGP, woot.

[onearmedbandit]

Yeah they have. This should be interesting.

[slowpoke]

Hmmm, desmodromics vs pneumatics, things are about to get verrrry interesting.......

[steved]

Haven't Suzuki and Kawasaki been using Pneumatic valves on their MotoGP bikes for a little while already?

http://blogger.xs4all.nl/daisy/archive/2007/07/03/254593.aspx

[steved]

They've been doing that in F1 for some time, haven't they?

Super mega high revving MotoGP, woot.

The problem will be not enough fuel. With the smaller 21L tank this year, you just can't keep increasing the revs to get more power. They are already pushing the envelope fuel-wise.

[TonyB]

Yeah, a few of them ran out just before the end of the race or on the cool down/ parade lap after. Buuuuuuut, the idea of high revving engine is to produce more HP by making the same torque higher up the rev range and make more torque at the back wheel by using lower gearing. Would reving higher necessarily use more fuel, particularly when the drag of operating valves no longer exists? I'm thinking they will be able to rev a whole lot higher and still use the same amount of fuel

[Mental Trousers]

That's a tad misleading. Pneumatic valves implies they get rid of the cams, cam chain etc, but they don't. All they do is remove the metal springs and replace them with pneumatic springs.
When you start getting silly revs out of engines the main limiting component is valve springs not being able to close the valves fast enough. If the valves don't close, the piston hits them and the engine becomes a handgrenade.
With gas, you just up the pressure when you up the revs. Then the limiting factors are things like conrods which have to hold onto even faster moving pistons.

[Skunk]

That's a tad misleading. Pneumatic valves implies they get rid of the cams, cam chain etc, but they don't. All they do is remove the metal springs and replace them with pneumatic springs.
That's true. But here's an interesting piece of info:

While pneumatic valve springs have become standard in Formula 1 engines, Renault has been researching computer controlled electromagnetic valves using no camshaft, to reduce moving parts while improving valve control.Renault being the pneumatic valve 'inventors'.

[slowpoke]

I understood that they can already make bike engines capable of phenomenal revs thanks to improved metallurgy, titanium valves etc but the problem is one of useability and tractability rather than ultra high revs.
The pneumatics will be used to allow cam profiles where the valve is opened and closed incredibly quickly without losing control of the valve as happens with springs. This is also the advantage of Ducati's desmodromic system. Compared to conventional springs this means that for the same duration cam more time is spent with the valve in the desired position (open/closed) rather than in transition, hence the engine is more efficient.

[sAsLEX]

That's a tad misleading. Pneumatic valves implies they get rid of the cams, cam chain etc, but they don't. All they do is remove the metal springs and replace them with pneumatic springs.


I have seen truck engines or maybe a prototype, lower revs, using ECU controlled rather than cam controlled air valves ( that pneu word is too hard to spell!) .

As each cam profile is a compromise, Honda get round it by effectively using two cams in vtech, cant be too long before we have the EFI equivalent of valve control.

[Crowdog]

Solinoid valves or ECU controlled would be the way to go as your cam would become electronic so you could have it as mild or as wild as you want anywhere in the rev range

[cowpoos]

Buuuuuuut, the idea of high revving engine is to produce more HP by making the same torque higher up the rev range and make more torque at the back wheel by using lower gearing. Would reving higher necessarily use more fuel, particularly when the drag of operating valves no longer exists? I'm thinking they will be able to rev a whole lot higher and still use the same amount of fuel

theres a heap of mechanical losses in a high reving engine based on friction on the reciprcating parts...and the inertia created by the parts reciprocating and super high speeds is not at all desired from a handling point of veiw..the higher a engine revs the stronger metals have to be..and they also generally get a lil heavier...I could carry on...theres heaps of reasons why high reving engines are anti-productive...in 1974 the tz500 two stroke race bike made 95-ish hp...and rev ceiling of 10,000rpm...in 2002... 195hp and a rev ceiling of 12500rpm...so that tells us theres heaps you can do a engine with development that doesn't involve raising the rev ceiling...
also they have to make an engine that is easy to ride...that also has an cosistant as possible loading on the rear suspension as possible...beable to give a tyre a breather between power pulse's...which are all easier to achieve with a lower reving V-twin like power delivery...


That's a tad misleading. Pneumatic valves implies they get rid of the cams, cam chain etc, but they don't. All they do is remove the metal springs and replace them with pneumatic springs.
When you start getting silly revs out of engines the main limiting component is valve springs not being able to close the valves fast enough. If the valves don't close, the piston hits them and the engine becomes a handgrenade.
With gas, you just up the pressure when you up the revs. Then the limiting factors are things like conrods which have to hold onto even faster moving pistons.

yep yep yep!!!!!!


I understood that they can already make bike engines capable of phenomenal revs thanks to improved metallurgy, titanium valves etc but the problem is one of useability and tractability rather than ultra high revs.

yep yep yep!!



The pneumatics will be used to allow cam profiles where the valve is opened and closed incredibly quickly without losing control of the valve as happens with springs. This is also the advantage of Ducati's desmodromic system. Compared to conventional springs this means that for the same duration cam more time is spent with the valve in the desired position (open/closed) rather than in transition, hence the engine is more efficient.

thats exactly what I believe to be the reason for the change to puematic valve springs...more control at higher lifts and duration...with better over all control.

[cowpoos]

on a side note...I wonder if any of the big teams have experimented with rotary valves...they have the advantage of being incredibly efficent once refined!!!

[imdying]

Very interesting... but the reason I posted it in 'Racing' was more that it's Yamaha doing it. Should be good value given that currently the only thing that every race we wonder what the effect of 'extra speed' the Ducati has will be. What does this mean for the championship? A bold move propelling Yamaha to victory? Or something that'll all alfict reliability and hand the championship to Ducati? Yamaha will probably well have their shit together before they use it, but...

[Kickaha]

theres a heap of mechanical losses in a high reving engine based on friction on the reciprcating parts...and the inertia created by the parts reciprocating and super high speeds is not at all desired from a handling point of veiw..

Which is why they're experimenting with electromagnetic valve actuation, then you can get rid of the camshafts,cam drive gear etc and have infinitely variable valve actuation

[cowpoos]

Which is why they're experimenting with electromagnetic valve actuation, then you can get rid of the camshafts,cam drive gear etc and have infinitely variable valve actuation
flow even more air with rotary valves!!

[SPman]

Haven't Suzuki and Kawasaki been using Pneumatic valves on their MotoGP bikes for a little while already?

http://blogger.xs4all.nl/daisy/archive/2007/07/03/254593.aspx
Aprilia used them on their triple....

Formula 1 cars are limited to 19,000rpm for their motors, but can spin to over 20,000!

[Brian d marge]

New news ? My ole Enfield has been using ignition variable cams for donkeys years ...

Stephen

Ps Fogot about the dukes desmo .. ( as you do ) yes they will be getting a lot of area under that valve lift chart ,,, and the drive out of the corners ...

Stephen

[BigG]

Personaly I think the problem is not the speed but the tyres, how many races this year have the tyres plaid a big part in the outcome of the races. Fitting a new motor can give Rossi more Hedaches, shure the Ducati's are alot faster but on the more technical tracks Rossi has been cleening up apart from rain affected races whare his choice of tyres was wrong. Going to be exciting though eh!

[vifferman]

Personaly I think the problem is not the speed but the tyres, how many races this year have the tyres plaid a big part in the outcome of the races. Fitting a new motor can give Rossi more Hedaches, shure the Ducati's are alot faster but on the more technical tracks Rossi has been cleening up apart from rain affected races whare his choice of tyres was wrong. Going to be exciting though eh!
True, but it's not Rossi's team that's made the mistakes - it's Michelin that's screwed up, and big time! If you look at each of the races (particularly the wet ones), if Rossi hasn't done well, then neither have most other riders with Michelin-shod bikes (Edwards, Pedrosa, Hayden, etc.) In fact, up until the last race, Michelin had done a crap job of supplying decent tyres, and the restrictive tyre rules operating this season have made it even more tricky. So far Bridgestones rule in the wet, so it'll be interesting to see if that's true for all wet races, or if Michelin can provide something that sticks and doesn't fall apart before the end of the race.

[SimJen]

http://www.kiwibiker.co.nz/forums/showpost.php?p=1109686&postcount=7

[vtec]

I had thought that F1 were already using electromagnetic valves, but that must have been false info. If you think about it that is the way to get pefect valve control with minimal ancillary components and mechanical drag. That is what they should be bringing to motogp in my opinion.

And cowpoos, I'm not familiar with these rotary valves. Could I get an explanation or a link?

[stanko]

Just get rid of the valves and all the associated whirring springy slappy gappy bits and return to real racers with no valves , bring back the 2 strokes !

[Kickaha]

and return to real racers with no valves ,

What about the reed valves? :lol:

[Sketchy_Racer]

What about the reed valves? :lol:

There's always one

:zzzz:

[cowpoos]

Just get rid of the valves and all the associated whirring springy slappy gappy bits and return to real racers with no valves , bring back the 2 strokes !


What about the reed valves? :lol:

YPVS....Yamaha Power Valve System

[cowpoos]

And cowpoos, I'm not familiar with these rotary valves. Could I get an explanation or a link?

Google is your friend :)

[k14]

Google is your friend :)
Ahh that makes sense. Guess they are quite bulky though. No springs to break or valves to hit the cylinder heads though. Guess its pretty much identical to the rotary valves in 2 strokes (ala aprilia 250 and 125 motogp bikes).

[cowpoos]

Ahh that makes sense. Guess they are quite bulky though. No springs to break or valves to hit the cylinder heads though. Guess its pretty much identical to the rotary valves in 2 strokes (ala aprilia 250 and 125 motogp bikes).
bulky!!! how deep is a modern DOHC head??
they have the potential to flow a high volume of air...I'm pretty sure one of the short comings of thier development was lubrication...but oils,metalology and techonology has come along way...I'm sure the short comings would easily be solved!!

[rwh]

Google is your friend :)

Interesting. I'm trying to figure out how that works. The in-car picture appears to show inlet and exhaust connecting to opposite ends of the head, but there's only one port in the head, so I guess the tube is split diagonally in the middle, with an inlet port on one side and exhaust on the other ... but not directly opposite, of course, since the inlet part of the cycle comes immediately after the exhaust - unless it doesn't rotate smoothly. I assume the sprocket visible in the vee of the block is geared down 2:1 from the crank as usual.

I'm assuming it's a 4-stroke, since otherwise the inlet and exhaust would have to overlap even more, and if the inlet doesn't go via the crankcase you'd need a supercharger or similar.

Sealing it sounds hard.

Richard

[cowpoos]

inlet port on one side and exhaust on the other ... but not directly opposite, of course, since the inlet part of the cycle comes immediately after the exhaust - unless it doesn't rotate smoothly.

turn the rotation of the valve the opposite way to your thinking in your head...the compression/firing stroke happens on the larger area of the valve that isn't ported...followed by exhaust....then inlet....comp...fire...



I assume the sprocket visible in the vee of the block is geared down 2:1 from the crank as usual.

I'm assuming it's a 4-stroke, since otherwise the inlet and exhaust would have to overlap even more, and if the inlet doesn't go via the crankcase you'd need a supercharger or similar.

its a 4 stroke...and it would have to be geared 2:1 other wise it wouldn't work...




Sealing it sounds hard.



have a closer look at the pic with the two rotary valves with heads shown away from the block...you can see three small ring like objects running the circumference of the valve....they are the seals....and they seal well...but I believe they are part of the lubrication isusse they had with them...and the wear placed on them was a lil high also I believe...

[cowpoos]

http://www.coatesengine.com/index.html

[FruitLooPs]

http://www.coatesengine.com/index.html


they do look the business!

This is also quite cool, looks like the whole 'keep it simple stupid' thing, hope they work well. :yes:
http://www.coatesengine.com/eGallery/pages/replaced-parts.htm

[Toaster]

Things are so techo nowdays, I dunno what to do with my spanner!

[slowpoke]

'Poos is onto a good thing.
I've seen simialr things done with fuel injection using rotary valves rather than throttle buttlerfly's and the flow potential is huge. If they can get rotary engine rotors to seal I don't see why this should be any more difficult.
I can't see it being any heavier than a camshaft/poppet valve set up, probably lighter as little strength is required unlike a camshaft which is hammering away at a spring actuated valve.
You'd think there would also be less maintenance involved as there wouldn't be any valve clearances to check/adjust.

[xwhatsit]

'Poos is onto a good thing.
I've seen simialr things done with fuel injection using rotary valves rather than throttle buttlerfly's and the flow potential is huge. If they can get rotary engine rotors to seal I don't see why this should be any more difficult.
I can't see it being any heavier than a camshaft/poppet valve set up, probably lighter as little strength is required unlike a camshaft which is hammering away at a spring actuated valve.
You'd think there would also be less maintenance involved as there wouldn't be any valve clearances to check/adjust.

<hints id="hah_hints"></hints>I bet the seals would be a bitch, though -- in terms of maintenance. And that's something you'd have to take the cam cover off for (except you can't call it that any more :D), instead of just poking a feeler gauge through the tappet covers.

[sAsLEX]

Things are so techo nowdays, I dunno what to do with my spanner!

Its in the biking culture that is predominating things as well these days.

Look at all the custom bike builders.......... all they do is use there spanners to bolt together parts. Was reading a magazine in America and the author was slating the new breed of "custom" bikes saying they were a cop out. He pointed at the Britten and the Indian saying they were true bike builders and that nothing these days compare.

Sure the knowledge needed to build a competitive engine/bike these days is a bit more but most of it can be learnt open source if you wanted, or just get a nerd friend to do the electrics?

[erik]

I thought one of the problems with rotary valves was that they can't open or close as suddently as normal valves can, so you can't get as much airflow?

[cowpoos]

I thought one of the problems with rotary valves was that they can't open or close as suddently as normal valves can, so you can't get as much airflow?
nope....would be interested to know where you heard that presumption??? rotary valves have a huge ability to flow air when compared to poppet valves...the timing/duration can have an effect on that...but you wouldn't design an engine to be low efficency for its design now would you??

[sAsLEX]

nope....would be interested to know where you heard that presumption??? rotary valves have a huge ability to flow air when compared to poppet valves...the timing/duration can have an effect on that...but you wouldn't design an engine to be low efficency for its design now would you??

One thing that seems rather obvious is you no longer have the valve head in the way of the airflow, or the associated turbulence past what is essentially a flat disc.

[Mental Trousers]

That's one of the major advantages of rotary valves - no obstructions in the airflow. Also, normal valves take up a certain amount of space inside the cylinder, space that could be better filled by the intake charge to give a bigger bang. The intake port and exhaust port volume's are also much larger for rotary valves. There's other advantages like less complexity, you'll never get the situation where valves contact the piston and handgrenade, piston crowns don't need cutouts for the valves so can be ideally shaped.
Some of the disadvantages are that the combustion chamber can never be an ideal shape as it has this large circular thing in the middle of it. Also, the spark plugs are no longer be in the middle so they usually need a twin plug arrangement, causing problems with merging flame fronts etc.
The single biggest hurdle for rotary valves is that the ordinary old poppet valve has been around forever, does the job required in 99.9% of cases, is proven technology and everybody knows the limitations. Nobody will risk multi million dollar racing budgets to develop a new (relatively) technology like rotary valves.

[Sanx]

&lt;muppet mode&gt; However, whilst a rotary valve can flow a large volume of air, isn't one of the advantages of the airflow passing over the head of a normal valve the turbulence it creates thus better mixing and distributing the fuel/air mixture?&lt;muppet mode&gt;

[Mental Trousers]

Yeah that's true. However, because the valve moves the turbulence isn't consistent over the length of a cycle so there's always a chance the mixture is uneven. Careful design usually sorts that problem out though. But the main thing is that the superior airflow of the rotary valves gives a significant advantage over the mixing from the turbulence that a poppet valve creates.
More air + fuel = more power.

[sAsLEX]

Yeah that's true. However, because the valve moves the turbulence isn't consistent over the length of a cycle so there's always a chance the mixture is uneven. Careful design usually sorts that problem out though. But the main thing is that the superior airflow of the rotary valves gives a significant advantage over the mixing from the turbulence that a poppet valve creates.
More air + fuel = more power.

And without the need for valve clearances on the top of the piston the piston top could be optimised to create a swirling/mixing what ever you want gas pattern

[erik]

nope....would be interested to know where you heard that presumption??? rotary valves have a huge ability to flow air when compared to poppet valves...the timing/duration can have an effect on that...but you wouldn't design an engine to be low efficency for its design now would you??

I can't remember where I heard it, I've tried searching the net and looking in a couple books i've got with no luck.

The reasoning was that if a rotary valve is turning at a constant speed, it's going to open gradually and close gradually and will only be fully open for an instant. But for a poppet valve controlled by a cam, pneumatics or electronics, it can be opened more quickly to the maximum opening, then be held at the maximum opening and then closed quickly.

I really can't remember where I heard it or if I'm getting it confused with something else...

[Mental Trousers]

The time it takes to fully open a rotary valve is always related to the engine speed as they are turning at 1/2 crank shaft speed, so therefore the time to fully open or fully close at any given rpm cannot be varied. However, if a poppet valve were to use something like solenoids to open them, in theory you can dial them in to open at any speed you want at any rpm.
So in theory a poppet valve that uses solenoids or some other method to open them (not a rotating cam) could fully open the valves faster, hold them open longer, then fully close them faster so that you get more mixture into the chamber.
The reality of it is that it's not the speed of the valve opening that's the problem but the piston. If the piston is at TDC and starts to move down the bore the valve has to follow the piston and therefore cannot open any faster. Camshafts are able to do exactly that now. So opening and closing the valves faster isn't actually going to help anything as they're governed by the speed the piston moves.

[Sanx]

The time it takes to fully open a rotary valve is always related to the engine speed as they are turning at 1/2 crank shaft speed, so therefore the time to fully open or fully close at any given rpm cannot be varied. However, if a poppet valve were to use something like solenoids to open them, in theory you can dial them in to open at any speed you want at any rpm.
So in theory a poppet valve that uses solenoids or some other method to open them (not a rotating cam) could fully open the valves faster, hold them open longer, then fully close them faster so that you get more mixture into the chamber.
The reality of it is that it's not the speed of the valve opening that's the problem but the piston. If the piston is at TDC and starts to move down the bore the valve has to follow the piston and therefore cannot open any faster. Camshafts are able to do exactly that now. So opening and closing the valves faster isn't actually going to help anything as they're governed by the speed the piston moves.

All of which begs the question why don't they use something else other than the crank to turn the rotary valves? I'm not sure a stepper motor could move fast enough, but there's no reason why you couldn't have pneumatic or electro-magnetic actuation of a rotary-type valve. Or at least a reciprocating valve that doesn't intrude on the cylinder at all. It's an appallingly crude diagram, but maybe something like the one attached.

[sAsLEX]

I can't remember where I heard it, I've tried searching the net and looking in a couple books i've got with no luck.

The reasoning was that if a rotary valve is turning at a constant speed, it's going to open gradually and close gradually and will only be fully open for an instant. But for a poppet valve controlled by a cam, pneumatics or electronics, it can be opened more quickly to the maximum opening, then be held at the maximum opening and then closed quickly.

I really can't remember where I heard it or if I'm getting it confused with something else...


The time it takes to fully open a rotary valve is always related to the engine speed as they are turning at 1/2 crank shaft speed, so therefore the time to fully open or fully close at any given rpm cannot be varied.


This issue could be solved with elliptical gears. You can have a fast opening time, a long pause on fully open and a fast shut.

[Mental Trousers]

All of which begs the question why don't they use something else other than the crank to turn the rotary valves? I'm not sure a stepper motor could move fast enough, but there's no reason why you couldn't have pneumatic or electro-magnetic actuation of a rotary-type valve. Or at least a reciprocating valve that doesn't intrude on the cylinder at all. It's an appallingly crude diagram, but maybe something like the one attached.


This issue could be solved with elliptical gears. You can have a fast opening time, a long pause on fully open and a fast shut.

Yup, both right. Using cam chains/belts/gears to drive the rotary valves off the crankshaft is relatively crude and difficult to vary (some of the VVT systems currently being produced can be bloody complex). In theory using VVT type systems on rotary valves would have a greater effect on them because poppet valves are limited by how fast and when they can open cos of the piston and clashing with the other valves.

[sAsLEX]

To help explain what I meant a picture
<img src=http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=66182&stc=1&d=1184493925>

Right hand side is rotating at a constant speed, ie crankshaft rate, whilst the other side is rotating at a varying pace!

[cowpoos]

The reasoning was that if a rotary valve is turning at a constant speed, it's going to open gradually and close gradually and will only be fully open for an instant

nope...depends on the size/shape of the porting and duration.


The time it takes to fully open a rotary valve is always related to the engine speed as they are turning at 1/2 crank shaft speed, so therefore the time to fully open or fully close at any given rpm cannot be varied..

thats correct...but...it depends how the are ported...how big the hole is?? how far around the duration its open for,etc a poppet valve engine's duration is specified by the cam shaft profile...and rotary valve engines duration is done with port size/shape/duration...same concept really...just a different way of doing it.


All of which begs the question why don't they use something else other than the crank to turn the rotary valves?

because they don't need too.


This issue could be solved with elliptical gears. You can have a fast opening time, a long pause on fully open and a fast shut.

good concept from a engineering point of veiw...but...it will have to be one mean arsed tensioning system to handle the forces while spinning at 5000+ rpm...ad maybe a lil unbalenced?

[Mental Trousers]

Yep. But the duration doesn't change how long the rotary valve takes to be 100% open/uncovered, just how long it's open for.
The time it takes for the leading edge of the rotary valve to be uncovered until that same edge gets to the otherside of the port is governed by how fast the rotary valve is rotating. Port shape can add time to how long it takes to achieve 100% wide open, but it can't reduce the time it takes for that leading edge to move from one side of the port to the other.

[cowpoos]

Yep. But the duration doesn't change how long the rotary valve takes to be 100% open/uncovered, just how long it's open for.
The time it takes for the leading edge of the rotary valve to be uncovered until that same edge gets to the otherside of the port is governed by how fast the rotary valve is rotating. Port shape can add time to how long it takes to achieve 100% wide open, but it can't reduce the time it takes for that leading edge to move from one side of the port to the other.
as in the same situation with a poppet valve re: opening and closing?? even with a massivly sprung poppet valve...

Don't think about it in the extremes of engine development as I thinkn you are....think of it as a everyday highperformance motor...like a gsxr,etc...

[Mental Trousers]

I'm just thinking theoretical rather than practical, ie the application is irrelevant. :)

[rwh]

I can see the elliptical (or even odder shape) gears (or sprockets) working on a single, or maybe even a twin, but I imagine it would be hard to get it right for more than that - unless you have more than one shaft.

Hmm - perhaps you could have a single central shaft running at constant speed, with elliptical gears driving each individual valve? More friction though.

Richard