Honda Power Unit Hardware & Software

[gruntguru]

The goal would be to supply the engine with the same amount of air regardless of altitude. This would require the same MAP and therefore a higher pressure ratio for the compressor and a higher VOLUME flow (measured at the compressor inlet) > higher turbo speed > higher pressure ratio for the turbine. Note - exhaust back pressure need not increase.

[PhillipM]

And since turbo speed is limited, it stands to reason a larger turbo would have more margin available than a small one.

[GhostF1]

And since turbo speed is limited, it stands to reason a larger turbo would have more margin available than a small one.

I don't believe the turbine speed is restricted, only the MGU-H speed is. But looking at this regulation made me think of something regarding altitude.

5.2.4 The MGU‐H must be solely mechanically linked to the pressure charging system. This
mechanical link must be of fixed speed ratio to the exhaust turbine and may be clutched.
The rotational speed of the MGU‐H may not exceed 125,000rpm.

What if Honda's current MGU-H/Turbo design now is indeed clutched, I say this because Renault said a couple of years ago that clutching the unit added a lot of complexity and would of degraded the reliability of the unit, Honda in 2017 said their design was high risk but required to catch the front runners and they went through a huge period of issues getting their MGU-H to work. Also in 2017, Yusuke Hasegawa was asked to comment on Honda's increased competitiveness in race trim at Mexico that year and he said the altitude seemed to affect them less than other manufacturers which levelled the field a little more...

A clutched MGU-H could allow them to have unique modes that would be handy at altitude, for example, there could be an unsustainable full deployment mode where the MGU-H is fully decoupled from the turbo which means the fixed speed ratio as specified by the regulation is no longer an issue and then allows them to increase the turbine/compressor speeds to compensate for the altitude.. another example could be a relatively sustainable mode where the MGU-H is coupled for a certain period/parameter (vehicle speed/track position/rpm/period of time) and then decoupled after that requirement has been met and then allowing them to increase turbine speed and therefore provide an increase in ICE power, whether that be for maximum acceleration or for a boost at very high speeds, allowing acceleration right up to the braking point instead of clipping or running out of steam.
The more I watch onboards of Max doing fast laps in recent races, the Honda has continued accelerating, and actually on some occasions looked and sounded like it stepped up at higher speeds in acceleration effort (noticed on the back straight of COTA during quali and Mexico etc).
The amount of ways this could be mapped would be endless. I'm just firing off random over excited thoughts on this occasion, but maybe it's an idea that's helping them at altitude.

[Maplesoup]

A clutched MGU-H could allow them to have unique modes that would be handy at altitude, for example, there could be an unsustainable full deployment mode where the MGU-H is fully decoupled from the turbo which means the fixed speed ratio as specified by the regulation is no longer an issue and then allows them to increase the turbine/compressor speeds to compensate for the altitude.. another example could be a relatively sustainable mode where the MGU-H is coupled for a certain period/parameter (vehicle speed/track position/rpm/period of time) and then decoupled after that requirement has been met and then allowing them to increase turbine speed and therefore provide an increase in ICE power, whether that be for maximum acceleration or for a boost at very high speeds, allowing acceleration right up to the braking point instead of clipping or running out of steam.
The more I watch onboards of Max doing fast laps in recent races, the Honda has continued accelerating, and actually on some occasions looked and sounded like it stepped up at higher speeds in acceleration effort (noticed on the back straight of COTA during quali and Mexico etc).
The amount of ways this could be mapped would be endless. I'm just firing off random over excited thoughts on this occasion, but maybe it's an idea that's helping them at altitude.

Could also perhaps explain the talk earlier in the season where Honda said they were having difficulties getting the mapping right for the car. I remember Max having issue with it before the summer break.

[saviour stivala]

All four power units have the MGU-H clutched to the turbo because if the MGU-H runs into “rotational” problems the turbo cannot rotate and if the turbo cannot rotate the engine is useless. With a rotating turbo and MGU-H declutched the engine can still be used.
With the MGU-H declutched or clutched but neither harvesting nor deploying the maximum turbo speed is still a maximum of 125000RPM.
The maximum power output mode possible regardless of altitude is still the so called ‘free load mode’ where the MGU-H is powering the turbo with waste-gates open and the ‘H’ sharing battery power with MGU-K.

[PlatinumZealot]

All four power units have the MGU-H clutched to the turbo because if the MGU-H runs into “rotational” problems the turbo cannot rotate and if the turbo cannot rotate the engine is useless. With a rotating turbo and MGU-H declutched the engine can still be used.
With the MGU-H declutched or clutched but neither harvesting nor deploying the maximum turbo speed is still a maximum of 125000RPM.
The maximum power output mode possible regardless of altitude is still the so called ‘free load mode’ where the MGU-H is powering the turbo with waste-gates open and the ‘H’ sharing battery power with MGU-K.

Show me your 120,000rpm clutch...
As far as I know there is no clutch or the need for one. The mguh has field current control to easily make up for speed and torque variations to give you the right voltage and loading that you need. Similar to the AVR on a generator.

[GhostF1]

All four power units have the MGU-H clutched to the turbo because if the MGU-H runs into “rotational” problems the turbo cannot rotate and if the turbo cannot rotate the engine is useless. With a rotating turbo and MGU-H declutched the engine can still be used.
With the MGU-H declutched or clutched but neither harvesting nor deploying the maximum turbo speed is still a maximum of 125000RPM.
The maximum power output mode possible regardless of altitude is still the so called ‘free load mode’ where the MGU-H is powering the turbo with waste-gates open and the ‘H’ sharing battery power with MGU-K.

Show me your 120,000rpm clutch...
As far as I know there is no clutch or the need for one. The mguh has field current control to easily make up for speed and torque variations to give you the right voltage and loading that you need. Similar to the AVR on a generator.

I feel like saying 120,000rpm as an insinuation there is no clutch is a little silly. What's stopping any sort of mapping solution allowing low turbo speed to re-engage with the MGU-H or vice versa. The regs say its allowable. Doubt it's not possible.

saviour stivala... they are not all clutched unless Renault decided to do a complete 180 on their position 2 years ago. And why is the turbo limited to 125,000rpm? There is no regulation stating this restriction, that applies to the MGU-H only and we have Honda stating in 2017 they spin the turbo harder at altitude circuits. So I can't see why the alternative is not possible

[PlatinumZealot]

All four power units have the MGU-H clutched to the turbo because if the MGU-H runs into “rotational” problems the turbo cannot rotate and if the turbo cannot rotate the engine is useless. With a rotating turbo and MGU-H declutched the engine can still be used.
With the MGU-H declutched or clutched but neither harvesting nor deploying the maximum turbo speed is still a maximum of 125000RPM.
The maximum power output mode possible regardless of altitude is still the so called ‘free load mode’ where the MGU-H is powering the turbo with waste-gates open and the ‘H’ sharing battery power with MGU-K.

Show me your 120,000rpm clutch...
As far as I know there is no clutch or the need for one. The mguh has field current control to easily make up for speed and torque variations to give you the right voltage and loading that you need. Similar to the AVR on a generator.

I feel like saying 120,000rpm as an insinuation there is no clutch is a little silly. What's stopping any sort of mapping solution allowing low turbo speed to re-engage with the MGU-H or vice versa. The regs say its allowable. Doubt it's not possible.

saviour stivala... they are not all clutched unless Renault decided to do a complete 180 on their position 2 years ago. And why is the turbo limited to 125,000rpm? There is no regulation stating this restriction, that applies to the MGU-H only and we have Honda stating in 2017 they spin the turbo harder at altitude circuits. So I can't see why the alternative is not possible

No good reasons to use on there and too many reasons not to use one there. It is silly to even think of it.
rubbish idea.

[GhostF1]

Show me your 120,000rpm clutch...
As far as I know there is no clutch or the need for one. The mguh has field current control to easily make up for speed and torque variations to give you the right voltage and loading that you need. Similar to the AVR on a generator.

I feel like saying 120,000rpm as an insinuation there is no clutch is a little silly. What's stopping any sort of mapping solution allowing low turbo speed to re-engage with the MGU-H or vice versa. The regs say its allowable. Doubt it's not possible.

saviour stivala... they are not all clutched unless Renault decided to do a complete 180 on their position 2 years ago. And why is the turbo limited to 125,000rpm? There is no regulation stating this restriction, that applies to the MGU-H only and we have Honda stating in 2017 they spin the turbo harder at altitude circuits. So I can't see why the alternative is not possible

No good reasons to use on there and too many reasons not to use one there. It is silly to even think of it.
rubbish idea.

Hmmm, your opinion I'd say. Don't think I'm at liberty to toss any idea out at this stage with these things

[saviour stivala]

"Show me your 120000 RPM clutch". I don't think that anybody can "show" what type clutch is used in detail between the MGU-H and turbo shaft outside of the teams themselves. We on this here discussion can only through technical experience express a personal opinion of what type of clutch is used. in my personal opinion it will be a type similar to the one-way-clutch used on the seamless/zero-shift gearbox. This type of one-way-clutch have the capability of also 'brake' when the rotational drive changes from one end to the other (drive by MGU-H shaft or drive by turbo shaft).
Because the rules mandate a maximum of 125K RPM for the MGU-H, it doesn't mean that it have to run at that maximum speed, it means it cannot exceed that speed. That the MGU-H have to be coupled to the turbo shaft and that it also can be clutched, unless a gearbox in between the two drives is used, the turbo speed will be the same. Re the possibility of the use of a gearbox in between the two shafts. On two out of the four power units on the grid where the 'H' shaft is coupled or clutched to the end of the compressor shaft it is a possibility. But how is it possible to use a gearbox on the other two which have the turbine at one end of the block and the compressor at the other end and the turbine/compressor shaft mandated to be 'one piece' with said shaft having to pass right through the 'H' drive tube?.

[sosic2121]

Show me your 120,000rpm clutch...
As far as I know there is no clutch or the need for one. The mguh has field current control to easily make up for speed and torque variations to give you the right voltage and loading that you need. Similar to the AVR on a generator.

I feel like saying 120,000rpm as an insinuation there is no clutch is a little silly. What's stopping any sort of mapping solution allowing low turbo speed to re-engage with the MGU-H or vice versa. The regs say its allowable. Doubt it's not possible.

saviour stivala... they are not all clutched unless Renault decided to do a complete 180 on their position 2 years ago. And why is the turbo limited to 125,000rpm? There is no regulation stating this restriction, that applies to the MGU-H only and we have Honda stating in 2017 they spin the turbo harder at altitude circuits. So I can't see why the alternative is not possible

No good reasons to use on there and too many reasons not to use one there. It is silly to even think of it.
rubbish idea.

I feel the same. IMO it would cause more problems than it would solve, if any.

[GhostF1]

"Show me your 120000 RPM clutch". I don't think that anybody can "show" what type clutch is used in detail between the MGU-H and turbo shaft outside of the teams themselves. We on this here discussion can only through technical experience express a personal opinion of what type of clutch is used. in my personal opinion it will be a type similar to the one-way-clutch used on the seamless/zero-shift gearbox. This type of one-way-clutch have the capability of also 'brake' when the rotational drive changes from one end to the other (drive by MGU-H shaft or drive by turbo shaft).
Because the rules mandate a maximum of 125K RPM for the MGU-H, it doesn't mean that it have to run at that maximum speed, it means it cannot exceed that speed. That the MGU-H have to be coupled to the turbo shaft and that it also can be clutched, unless a gearbox in between the two drives is used, the turbo speed will be the same. Re the possibility of the use of a gearbox in between the two shafts. On two out of the four power units on the grid where the 'H' shaft is coupled or clutched to the end of the compressor shaft it is a possibility. But how is it possible to use a gearbox on the other two which have the turbine at one end of the block and the compressor at the other end and the turbine/compressor shaft mandated to be 'one piece' with said shaft having to pass right through the 'H' drive tube?.

I'm sorry, I feel like you're either contradicting yourself or you misunderstand.

The turbo IS NOT speed limited by regulations, only the MGU-H is limited and while I am well aware that if the MGU-H was NOT clutched, the turbo would be directly coupled to it with a FIXED speed ratio (as per regulations), however, just a thought, 1. That does not necessarily imply they are geared 1:1 to each other, 2. If they were, I understand that would limit turbo speed to 125,000rpm due to the MGU-H speed limit reg.

What I'm suggesting is, if it is clutched and can at various points, be "decoupled" from the turbo shaft with this "clutch", then it would be technically possible and, more importantly, legal to run the turbo at a higher rpm during this decoupled state, obviously for the H to be coupled again, turbine speed would have to abide to a certain speed required to keep the H below max allowed.. but in any scenario, there is no need for this "gearbox" you are suggesting... None whatsoever.

And just on the complexity front.. I'm well aware the complexity is enormous adding this function, but I'm just speculating based off comments from Honda over the last few years where they themselves claim they went, and ai quote.. "very high risk with this design" and that it was "the only way to get a jump on the front runners, by adopting this technology", combine this with ENORMOUS MGU-H issues they had in 2017 and the failure in Australia 2018 (which Honda claim was due to their upgraded design not being ready for use until Bahrain), it isn't completely impossible they did implement something as complex as that. All signs point to something different going on there. Even to the point where in 2017, the MGU-H and Turbo were housed as one entire unit and couldn't be changed separately of each other. I mean, developing a singular, rigid housing for these components is at least curious...

We know they've since improved the design to be modular now, but as I said earlier, All signs point to something different going on there and apart from it being "highly complex to implement", I can't at the moment see why it wouldn't be possible

[PlatinumZealot]

I am gonna give the clutch sayers the benefit if the doubt and try to sketch some possible arrangements....

[saviour stivala]

The rules state that the ‘H’ (shaft) is to be couplet to the turbo shaft and that it can also be ‘clutched’.
If there is no step-up or step down gearbox in between these two shafts (H and turbo shafts) the speed of the ‘H’ and the turbo is the same.
The scope of these shafts being ‘clutched’ is for the turbo and so the engine being able to be used in case the ‘H’ is damaged.
Although not part of the subject at hand, the ‘K’ having a mandated maximum of 50k RPM and the crankshaft a mandated maximum of 15k rpm does have a gearbox in between as well as a clutch.

[rgava]

The problem I see with the theory behind the "clutched" connection between turbocompressor shaft and MGU-H is that:
In order to use the MGU-H to harvest energy, the turbine should be bigger than the needed to propel the compressor.
If the clutch disconnects the MGU-H from the turbocompressor shaft, the result will be a quick increase of rotational speed (very difficult to control).
The only way I can think of to control the shaft speed in such scenario are the Wastegates.
IMHO, it is almost impossible to have a quick enough reaction to get back the turbocompressor speed to the necessary to engage again the MGU-H with the clutch.
I can see it as a fail safe feature in case of MGU-H faillure.
But, even though, the advantages of such a fail safe approach most probably are neglected by the penalty in rotational inertia and friction losses introduced by the clutch system.