Honda Power Unit Hardware & Software

[aleks_ader]

Oh, no. Unequal length runs to the intercoolers? This hurts my perfectionist side. Go watercooled, Newey-Honda. The teams that win races are doing it.

I SUPPOSE it doesn't matter. Couple miliseconds? I doubt it could cause problems inside plenum.

[Tommy Cookers]

“The slip work I suggested” From memory of the Honda paper read, but all the same, I went back and read it all over again, that was exactly what I suspected (That it was your suggestion) and not what Honda was doing (nothing to do with the Honda paper). If you believe that a formula one clutch will last a race with that sort of in-designed slip I have no problem with that, all I have is real doubt.

the Honda paper that I named doesn't in any way suggest the slip ('clutch adaptation') is only for starts
and eg it shows an upshift shift to 4th gear - and it shows downshifts
CA from c2007 replaced the earlier shift system that caused wheelspin with the CA system that eliminated wheelspin
so presumably this is basically what is used today

in 4th gear from 10500 to 12200 rpm the PU traps in rotation c. 5% of the energy that would ideally all accelerate the car
(the trapped percentage is of course higher in lower gears than 4th)
with CA somewhat less of this energy is released to the wheels (on upshifts) but acceleration etc is greater as wheelspin is eliminated

in higher gears the withheld energy has less % acceleration value and timing is anyway less useful
and (in the higher gears) there would be no wheelspin even without CA
but presumably 'they' all use CA systems in the lower gears throughout the race (for upshifts and downshifts)

are clutch plates consumable parts - or parts that must last as many races as the gearbox ?

[henry]

are clutch plates consumable parts - or parts that must last as many races as the gearbox ?

They are replaceable under supervision because it involves seal breaking.

[gruntguru]

“The slip work I suggested” From memory of the Honda paper read, but all the same, I went back and read it all over again, that was exactly what I suspected (That it was your suggestion) and not what Honda was doing (nothing to do with the Honda paper). If you believe that a formula one clutch will last a race with that sort of in-designed slip I have no problem with that, all I have is real doubt.

the Honda paper that I named doesn't in any way suggest the slip ('clutch adaptation') is only for starts
and eg it shows an upshift shift to 4th gear - and it shows downshifts
CA from c2007 replaced the earlier shift system that caused wheelspin with the CA system that eliminated wheelspin
so presumably this is basically what is used today

in 4th gear from 10500 to 12200 rpm the PU traps in rotation c. 5% of the energy that would ideally all accelerate the car
(the trapped percentage is of course higher in lower gears than 4th)
with CA somewhat less of this energy is released to the wheels (on upshifts) but acceleration etc is greater as wheelspin is eliminated

in higher gears the withheld energy has less % acceleration value and timing is anyway less useful
and (in the higher gears) there would be no wheelspin even without CA
but presumably 'they' all use CA systems in the lower gears throughout the race (for upshifts and downshifts)

are clutch plates consumable parts - or parts that must last as many races as the gearbox ?

Agree 100%. I don't recall what the ratio gaps are in these gearboxes, but a seamless shift requires a sudden drop in rpm of perhaps 15%. The kinetic energy released in slowing the moving parts of the engine and MGUK by 15% would be considerable and in the few milliseconds available, the 120 kW braking from the MGUK would not absorb all this energy. Te only alternative is to dissipate some of the energy as heat - by slipping the tyres or the clutch. I know which of these the driver would prefer.

[PhillipM]

The tyres, there's a lot more potential to store energy in the driveline after the diff, whereas the clutch pack is tiny it's heat capacity is about that of a cup of water.

[GhostF1]

Don't mean to be taken off foot here, but have we actually gotten anywhere with this clutch slip conversation? Or is this a nowhere conversation fuelled by disagreements (mostly over an irrelevant article to this topic) from the usual suspects that pose no significant discussion relating to this current power unit... the conversation of it has grown tiresome, pretty sure I've read the same paragraph in one form or another about 10 times now.

[roon]

Advancing combustion momentarily could provide some engine braking. Small fuel injection and ignition before TDC. Combustion events at about 600 Hz. 2 ms for one event, 12 ms for six. Time these early small braking ignitions after shift request, and prior to selector action and during any clutch activity. Combine with MGUK activity. Workable?

[GhostF1]

Advancing combustion momentarily could provide some engine braking. Small fuel injection and ignition before TDC. Combustion events at about 200 Hz. 5 ms for one event, 30 ms for six. Time these early small braking ignitions after shift request, and prior to selector action and any clutch activity. Combine with MGUK activity. Workable?

It's definitely viable.
Though off throttle noise insinuates ignition cut to me, this combined with mapping it to keep the throttle open would also provide an engine braking effect. A lot of possibilities

[saviour stivala]

Advancing combustion momentarily could provide some engine braking. Small fuel injection and ignition before TDC. Combustion events at about 200 Hz. 5 ms for one event, 30 ms for six. Time these early small braking ignitions after shift request, and prior to selector action and any clutch activity. Combine with MGUK activity. Workable?

It's definitely viable.
Though off throttle noise insinuates ignition cut to me, this combined with mapping it to keep the throttle open would also provide an engine braking effect. A lot of possibilities

Contrary to you I find your lot interesting, valid to the subject and repeatability doesn’t bother me. As a result I read your lot and have no complains to make as to relevance and contribution to the thread in hand. That is because it is a right of yours to discuss with others different points than that of others are/might be discussing.

[saviour stivala]

The tyres, there's a lot more potential to store energy in the driveline after the diff, whereas the clutch pack is tiny it's heat capacity is about that of a cup of water.

Phillip. Re clutch heat capacity, I wouldn't say its heat capacity is about that of a cup of water because the clutch can absorb a hell of a lot of heat, even if momentarily. I would say that the clutch of a formula one car is a very critical part indeed.

[Tommy Cookers]

the heat from slip work is rather small and the priceless Honda data shows this
and remember the biggest benefit of this is making the gearbox dogs last 5 or 7 or whatever races

each upshift slip episode lasts a few millisec
slip is only partial ie reducing torque peak by about 40%
there must have been more clutch slip in traditional systems deliberately or as an unavoidable side-effect
(were race clutches sized to transmit momentary over-torque or 'small is better' sized, slipping away this over-torque ?)

the wheel slip (that has been eliminated) was 'only' about 1 axle rev worth
(but followed by a 'rebound' in wheel rotation, also inefficient and now eliminated)

the shift events in the gearbox take less time than 1 crankshaft rev
nothing else affecting shift behaviour can be quite so fast acting
not ICE throttling or fuel cutting or MGU-K action
(ok some of these could be started before the shift action - and Honda telemetry seems to show such K action)
not even clutch action (or any practicable or even legal ie passive form of transmission shock absorption)

but most or all of these elements are present and having an effect
so must be orchestrated by design and development
otherwise there will again be here a rain of posts about Honda response/transmission issues

sorry, Ghost

[saviour stivala]

The formula 1 clutch is used at race starts, pits stops and anytime the driver decides to get the car into a spin and stop moving. The formula 1 clutch plays no part during gear shifting up or down. With a sequential type seamless shift gearbox there is no loss of power or torque delivery to the rear wheels during shifts and neither a requirement of the clutch after first gear. Heat in the clutch can only be generated by slipping. In my opinion a formula 1 clutch is as consumable an item as the brake discs and pads, and I believe that these items are not re-used for more than one race.

[Bandit1216]

Hi all.

With seamless shift. There would always be and amount of kinetic energy in the rotation mass of the engine, being slowed down to next gear rpm, within ms. IMO not only will there be no power loss, but kinetic energy will be absorbed somewhere in the driveline somehow. Or do I miss something here?

[henry]

Hi all.

With seamless shift. There would always be and amount of kinetic energy in the rotation mass of the engine, being slowed down to next gear rpm, within ms. IMO not only will there be no power loss, but kinetic energy will be absorbed somewhere in the driveline somehow. Or do I miss something here?

I think there are three things that can happen to the kinetic energy.

It can be transmitted, that is it can be used to accelerate the car. There may be a delay in the transmission as various flexible elements in the train from crank to road absorb and then release energy.

It can be dissipated, that is turned into some other energy, heat from slipping the clutch or tyres, electrical energy by driving the MGU-K (which itself contributes to the kinetic energy), or ICE pumping work.

It can be ameliorated, that is the ICE and MGU-K can reduce their output to reduce the need for slip, or provide spare capacity in the flexible elements. Things like ignition cut, fuel cut timing changes.

Other posters, notably @Tommy Cookers, have provided examples and explanations of all of these but I, personally, find it useful to have boxes to put things in.

[PhillipM]

Phillip. Re clutch heat capacity, I wouldn't say its heat capacity is about that of a cup of water because the clutch can absorb a hell of a lot of heat, even if momentarily. I would say that the clutch of a formula one car is a very critical part indeed.

An F1 clutch is tiny, the discs are about 3" in diameter, you could hold all the friction discs, plates and basket in the palm of your hand.