2014-2020 Formula One 1.6l V6 turbo engine formula

[wuzak]

fwiw my guess (from a bit of experience)
the electromagnetic time constant of the H is regardable as 20 msec bare and 40 msec incl inertias eg turbine and compressor ie it can accelerate (in vacuum) in 40 mSec to 63% of any step change in demanded rpm so 8% change in rpm in 20 mSec seems not implausible even with the high and strongly rpm-related compressor loads

it now seems to me that with DI the ICE torque turndown and turnup can be a few msec ('1 rev')
iirc the time window when 2 gears load path components are in position simultaneously is 4 msec ('1 rev')
the time constant of ICE/K rpm is maybe 30 msec ie16% rpm turndown in 10 msec seems possible

Some great info in that post Tommy.
What is the power required to accelerate the H from say 120k rpm to 130k (120k + 8%) in 20 mSec?

Definitely plausible - if needed they could change the setpoint for the H before the gearshift even started.

If you accelerated the H to 130,000rpm you would be cheating!

The H has a maximum speed of 125,000rpm.

[henry]

Gruntguru,

My calcs suggest the power required to go from 110k to 119k is around 180 kw.

When looking at the Honda K - H charging I got:

120 Kw for 25 ms (20 hz)

Start rpm 110000
End rpm. 117700

I used constant torque rather than constant power, but given I’m guessing the inertia and the speed range is small it doesn’t make much difference.

That’s after I fixed the inertia I was using in the light of Tommy Cooker’s insights.

For reference I’m using 3.214E-04 kgm^2 which is a Rotrex C38-61s. http://www.rotrex.com/media/259f22f7-f3 ... nertia_pdf

The inertia given is referred through a gear ratio of 7.5:1, I missed that first time round.

Comparing this compressor with MGU-H assembly is a stretch, I think the inertia I’m using might be low so if anybody has a better inertia figure I can pop it into my calcs.

[johnny comelately]

However, I was suggesting that in that 20 milliseconds for an upshift to achieve constant lambda the boost needs to rise substantially. I don’t think it can because there isn’t enough power to drive the boost making assembly. So I think lambda is likely to be variable.
As supporting evidence for the inertia of the MGU-H and TC we know that Honda have used it to transfer energy from MGU-K to the ES via that assembly.

upshifting gives a rev drop of c.16%
so fuel charge/cycle will rise 16% and air charge/cycle must rise 16% to maintain lambda
so the new absolute 'boost' pressure should be 16% higher
this is roughly equivalent to a required H rpm increase of c. 8%

fwiw my guess (from a bit of experience)
the electromagnetic time constant of the H is regardable as 20 msec bare and 40 msec incl inertias eg turbine and compressor
ie it can accelerate (in vacuum) in 40 mSec to 63% of any step change in demanded rpm

so 8% change in rpm in 20 mSec seems not implausible even with the high and strongly rpm-related compressor loads


it now seems to me that with DI the ICE torque turndown and turnup can be a few msec ('1 rev')
iirc the time window when 2 gears load path components are in position simultaneously is 4 msec ('1 rev')
the time constant of ICE/K rpm is maybe 30 msec ie16% rpm turndown in 10 msec seems possible

Tommy,
I want you to know that everytime you write something here I lose a day out of my life working it out or not

[henry]

A further thought on gearchange.

If fuel is cut for the change the exhaust is also cut and the turbine no longer drives the compressor, so the MGU-H has to compensate and it’s duty will go up.

[J.A.W.]

The split second cut would surely be too short to affect compressor inertia, or cause a stall condition?

[63l8qrrfy6]

The engine is developing full torque throughout the shift.
It has been so ever since they've introduced seamless shift gearboxes.

[Tommy Cookers]

then how does it slow eg from 12200 rpm to 10500 rpm ?

there is a lot of energy stored in the PU's rotation at 12200 rpm
where does the energy go ?
the energy difference between the energy at 12200 rpm and the energy at 10500 rpm

are you saying it is all passed through parts that are trying to shift and on to/from Planet Earth ?


we've seen telemetry showing the K generating momentarily with upshifts and motoring momentarily with downshifts

[johnny comelately]

then how does it slow eg from 12200 rpm to 10500 rpm ?

there is a lot of energy stored in the PU's rotation at 12200 rpm
where does the energy go ?
the energy difference between the energy at 12200 rpm and the energy at 10500 rpm

are you saying it is all passed through parts that are trying to shift and on to/from Planet Earth ?


we've seen telemetry showing the K generating momentarily with upshifts and motoring momentarily with downshifts

if during changes there is partial (10%?) fuelling (as mentioned somewhere else) it will fire in the exhaust spooling the turbo. my basic view and still trying to work out why this is important

[godlameroso]

The turbo also harvests electrical energy?

[henry]

The split second cut would surely be too short to affect compressor inertia, or cause a stall condition?

We’ve discussed the effect on compressor inertia, or at least the whole assembly. Depending on what you think the compressor power is the split second (20 millisecond) might reduce the speed by 5% when you need it to go up to maintain constant lambda. Whether that is significant I don’t know, but it has to happen.

[johnny comelately]

The split second cut would surely be too short to affect compressor inertia, or cause a stall condition?

We’ve discussed the effect on compressor inertia, or at least the whole assembly. Depending on what you think the compressor power is the split second (20 millisecond) might reduce the speed by 5% when you need it to go up to maintain constant lambda. Whether that is significant I don’t know, but it has to happen.

what about the role of the plenum?

[J.A.W.]

Indeed Johnny, the whole gas column, right through the turbine - must surely obey Newton's findings..

The dynamic gas volume/pressures, along with the recip machinery - has to have quantifiably significant inertia.

[johnny comelately]

Does anyone know the layout of the sensors for temp, maf (what type?), map etc and who supplies them?

[henry]

The split second cut would surely be too short to affect compressor inertia, or cause a stall condition?

We’ve discussed the effect on compressor inertia, or at least the whole assembly. Depending on what you think the compressor power is the split second (20 millisecond) might reduce the speed by 5% when you need it to go up to maintain constant lambda. Whether that is significant I don’t know, but it has to happen.

what about the role of the plenum?

Good point, The objective, to maintain lambda on upshift, would be to do everything possible to increase pressure, so maybe they close the throttles. On downshift they might dump from the plenum to the compressor intake.

I don’t know. What do you think?

[henry]

The turbo also harvests electrical energy?

A pedant wouldn’t say so.

What usage condition are you referring to?