F1technical.net

xpensive wrote:

timbo wrote:I wonder, with a 15k rev limit, and possibly even less used because of limited fuel-flow, wouldn't it make sense to try conventional springs instead of pneumatics?
The cons are obvious -- resonances in springs were limiting the rev band up to 11k-12k, the pros are elimination of nitrogen supply bottle and possible simplification of valvetrain.

Interesting thought, even if the hysteresis of conventional springs would mean a power-loss in itself, constant-pressure pneumatics don't have that problem. But how much, I have no idea, anyone?

the 2014 job should be a walk in the park for metal valve springs (ie timbo's suggestion seems good)

surely hysteresis has never been regarded as signicant or a problem in metal valve springs ?
excessive heating (from any source) of a metal valve spring must be undesirable, but is easy to deal with ?
hysteresis would be least what we classify as torsional strain (maybe Honda knew that when choosing torsion valve springs)

any material that has a clear and (relatively) long elastic range should have trivial hysteresis over a much of that range
that's what makes eg a good 'spring' grade of metal
most load cells are basically metal springs, and they make quantified claims of very low hysteresis eg 0.1%
(true, helped by selecting the hysteresis properties of the strain-sensing element to part-cancel hysteresis in the springs)

isn't hysteresis inherent in gas springs though ?
the difference between isothermal and adiabatic deflections in a gas spring represents the potential 'hysteresis' of a perfect gas ?
(though this has little effect at valve spring speeds ?)
and our gas springs are made from real gas, not perfect gas, and so have hysteresis effects from additional sources

equivalent and analagous behaviour does occur in even the best metal spring material, this impedes measurement of hysteresis
(my estimate from attempted practical investigation is around 0.2% hysteresis at valve spring levels of strain)

so what would 0.2% 'hysteresis' from whatever source do to a metal valve spring regarding cooling needs and power loss ??
and how could this be worse in those respects than a gas valve spring ??

Looking at Wikipedia, the Renault EF15 Type-B in 1986 was the first F1 engine to use the pneumatic springs. It revved up to 12.5k rpms. Although motorcycle crotch rockets use double springs up to 13k and more.

Would there be any weight, performance or reliability advantage of conventional springs over the well established pneumatic valve springs?

piast9 wrote:Would there be any weight, performance or reliability advantage of conventional springs over the well established pneumatic valve springs?

IMO there would be a weight and packaging advantage. The pneumatic valves depend on nitrogen feed as they are always leaking (remember 2010 Ferrari engine problems were because of leaking valvetrain).

Why aren't we hearing about the ferrari engine?
Do they even have one?

ringo wrote:Why aren't we hearing about the ferrari engine?
Do they even have one?

I'm actually more interested in why Renault and Merc chose to show their "engines" that early.

One of the biggest reasons to run pneumatic springs is that they allow for less clatter and bounce.

During the pre-gp grid walk the Italian tv technical commentator ing.Giancarlo Bruno, has shown the Magneti Marelli MGU-H for 2014 (presumably an early development version):




He said that it will produce 120hp revving at 120k rpm (rules allow up to 125k). No mention about the weight, but he was "playing" with it rather easily with a single hand, so I doubt we are talking about 10kg or more, probably something like 5-7 at max.

For a comparison, in 2011 Bruno had shown the 60 kW KERS of 2009 and 2011 (with carbon shell), he claimed the latter was 30% lighter. (apologize for the worse quality of these but I had still the old recording equipment back then):

Hmm, very clever technology if it is that light.
I am not happy with an unarmoured unit that will presumably sit on top of the powertrain rotating at such hugely high revs.
I hope the FIA is considering a kevlar blanket in the engine cover before any spectators get shot with shrapnel.

autogyro wrote:Hmm, very clever technology if it is that light.
I am not happy with an unarmoured unit that will presumably sit on top of the powertrain rotating at such hugely high revs.
I hope the FIA is considering a kevlar blanket in the engine cover before any spectators get shot with shrapnel.

Yes good idea! And also it is pretty easy to implement into carbon "prepreg" fabric.

89kW... hmm sounds interesting.
So clearly it can't harvest most of the thermal energy from the exhaust gas.
I believe it may harvest more than stated by the Italian guy presenting it. MM probably gave him a harmless number to work with.
If this thing is harvesting much of the time from the engine, then it doesn't leave much work for the KERS now does it?

ringo wrote:89kW...
So clearly it can't harvest most of the thermal energy from the exhaust gas.
I believe it may harvest more than stated by the Italian guy presenting it

89 plus a bit sounds like backpressure giving improved fuel-efficiency ?
it looks good IMO given that Wright said about 65% of the exhaust energy was unavailable to a turbine

Tommy Cookers wrote:

ringo wrote:89kW...
So clearly it can't harvest most of the thermal energy from the exhaust gas.
I believe it may harvest more than stated by the Italian guy presenting it

89 plus a bit sounds like backpressure giving improved fuel-efficiency ?
it looks good IMO given that Wright said about 65% of the exhaust energy was unavailable to a turbine

89 kW, or 120 Hp, sounds a bit much, but there are a lot of strange numbers thrown around these days-

dren wrote:Looking at Wikipedia, the Renault EF15 Type-B in 1986 was the first F1 engine to use the pneumatic springs. It revved up to 12.5k rpms. Although motorcycle crotch rockets use double springs up to 13k and more.

FWIW the Indycar engines use conventional (but extremely good quality) coil steel valve springs and run them to 16,000 rpm.
I was thinking about the use of coil springs in the new V6 F1 engines and dug this thread up because of it.
I suspect that if the F1 engineers can get steel springs working at the revs and cam profiles the V6 engines use, it'll be a useful weight saving as they don't have to carry all the pneumatic gear.

ringo wrote:89kW... hmm sounds interesting.
So clearly it can't harvest most of the thermal energy from the exhaust gas.

We already knew that. 120hp is a good amount, though, and more than I expected.

ringo wrote:I believe it may harvest more than stated by the Italian guy presenting it. MM probably gave him a harmless number to work with.

They probably haven't given the full details, but I would be surprised if they ran a 120hp unit to capacity. In other words, there is probably still room for improvements to the turbine efficiency and recovery before they have to upsize the unit.

Doubtful that they would ever need 120hp for spooling up (in motor mode).

ringo wrote:If this thing is harvesting much of the time from the engine, then it doesn't leave much work for the KERS now does it?

At the top end. There will be plenty of time duing the lap where the MGUH will not be generating full power. And the MGUK will be used to help punch the cars off the corners, IMO.

Goes along with my theory that they won't have the full allowed storage capacity - the energy won't remain in storage for very long. Make it, use it.