Honda Power Unit Hardware & Software

[Tommy Cookers]

And the reason you feel it's wrong is ?

at entry to a corner the open diff (all the while applying equal torque to both driveshafts) ....
starts to allow rpm acceleration of the outer wheel and rpm deceleration of the inner wheel
the torque reaching the outer wheel contact patch is reduced by the torque taken to accelerate the wheel's inertia ....
the torque reaching the inner wheel contact patch is increased by the torque given in decelerating the wheel's inertia ..

the net effect on entry is some yawing moment that acts in the direction opposite to the cornering required

[Farnborough]

But thats not the route braking torque takes from powerplant restricted input.

If the input shaft is held (motor braking) then the outer wheel turned in correct direction of travel, the only reaction the inner radius wheel can make it to turn comparatively backwards in relation to the outer wheel by spinning the diff planetary. This causing reduction in contact patch speed for the inside wheel, hence a bias braked axle.

The wheel inertia is relatively minimal in comparison to tyre patch traction against brake torque as I view it.

[Farnborough]

Additionally, the wheel acceleration inertia, surely that's theoretical and running in unloaded state ?

Obviously wheel inertial resistance is a factor in acceleration, this braking entry into a corner scenario has all of the components in rotation bringing deceleration by using stored vehicle inertia/kinetic else it wouldn't run regenerative facility.

The outside wheel on a vehicle is very rarely brought to traction limits across a differential, it's always the inner wheel in either traction or braking that yealds. This difference will steer the vehicle by having increased retardation through that route in comparison to the outside wheel.

Although not across a differential, Honda have very long history of engine braking enhancement and control via motorcycles, since the 1970s in reality.

[gruntguru]

Neglecting wheel inertia for the moment.
With an open diff, the torque at each wheel is identical and in the same direction (both wheels driving or both braking).
So TC is right - no yawing moment.

With all types of passive LSD, a yawing moment is produced - opposing the turn. Same goes for wheel inertia.

Only an active differential (ie torque vectoring) can apply a yawing moment into the turn.

[Zynerji]

Neglecting wheel inertia for the moment.
With an open diff, the torque at each wheel is identical and in the same direction (both wheels driving or both braking).
So TC is right - no yawing moment.

With all types of passive LSD, a yawing moment is produced - opposing the turn. Same goes for wheel inertia.

Only an active differential (ie torque vectoring) can apply a yawing moment into the turn.

FYI to the project car guys. The torque vector differential from the Nissan Juke is available on Ebay for about $150usd. Good for 250hp, and able to be actively controlled with an Arduino.

[Farnborough]

The differential (open type) have the characteristics listed only when the load is equal in each route through.

That's the inherent limit of open diff, and why slip limited facility is incorporated.

This method uses the fault side of that principle to the dynamic advantage.

If you braked an axle through the pinion input, then all things being equal, those listed above attributes take place.

If you braked an axle through the pinion on a vehicle rolling downhill, then just lift one wheel (reduction in traction on that one only) then it will start to rotate backwards relative to the other wheel.

Now if the driver brakes hard with transmission as primary, rear of chassis rises, starts to roll, reduces inside wheel traction, the planet gears start to spin slowly to give the bias to braking effort across the axle.

MV has for a long time been different to many in braking phase. Performance in wet at Pau prior to F1. Torro Rosso down toward juncao Brazil (rear initiallylet go), pulling downshift to bring car straight again. Ditto in RB on that famous one coming up to pit entry area of track, downshift while letting the chassis pull itself straight instead of rotation into spin. Habitually using significant downshift in extremis, his driving style is facilitated by this element in power train.

Power train braking also gives anti lock too as it'll not usually bring wheel to standstill like a caliper and disc. Compare in car of braking phase to others, his words in Bahrain with reference to locking on downshift, also in jeddah I believe reference downshift too slow. Its a critical area of performance to his/their advantage as I see it. It's self modulating too, in it's distribution and depending on immediate chassis loading.

[AR3-GP]

The differential (open type) have the characteristics listed only when the load is equal in each route through.

That's the inherent limit of open diff, and why slip limited facility is incorporated.

This method uses the fault side of that principle to the dynamic advantage.

If you braked an axle through the pinion input, then all things being equal, those listed above attributes take place.

If you braked an axle through the pinion on a vehicle rolling downhill, then just lift one wheel (reduction in traction on that one only) then it will start to rotate backwards relative to the other wheel.

Now if the driver brakes hard with transmission as primary, rear of chassis rises, starts to roll, reduces inside wheel traction, the planet gears start to spin slowly to give the bias to braking effort across the axle.

MV has for a long time been different to many in braking phase. Performance in wet at Pau prior to F1. Torro Rosso down toward juncao Brazil (rear initiallylet go), pulling downshift to bring car straight again. Ditto in RB on that famous one coming up to pit entry area of track, downshift while letting the chassis pull itself straight instead of rotation into spin. Habitually using significant downshift in extremis, his driving style is facilitated by this element in power train.

Power train braking also gives anti lock too as it'll not usually bring wheel to standstill like a caliper and disc. Compare in car of braking phase to others, his words in Bahrain with reference to locking on downshift, also in jeddah I believe reference downshift too slow. Its a critical area of performance to his/their advantage as I see it. It's self modulating too, in it's distribution and depending on immediate chassis loading.

As far as I am aware, they are not permitted to use "chassis loading" as a signal to influence anything with the PU . As this would be traction control . I think only a kill switch is permitted as a result of a crash.

[Farnborough]

I can see that view, regarding chassis loading.

But to clarify, no system or "mode" simply as soon as the driver brakes and turns the chassis it will always unload the inside rear tyre. It's this that gives the traction difference across the half shafts that purely mechanical differential leverage responds to. Its in every single differential vehicle, depends how the driver uses it.

The "mode" if that's what someone would described it as, is purely how much transmission braking the driver wants to load onto it with their skill set during that brake phase.

It's far more a rally driver style rather than pure track driver. May not be ultimately the fastest absolute in pure driven lap time, but in hand-to-hand hand combat may simply give track position which is vital.
It should have the side effect of preserving outside front tyre life as well by reduction of that being less in demand to turn the chassis.

Have a look at MV overtake on LH in Cota last year, or GR into final corner at a jeddah this year to see absolute pace in critical brake/turn phase.

[AR3-GP]

Power train braking also gives anti lock too as it'll not usually bring wheel to standstill like a caliper and disc.

Interesting. I never thought about this.

[Farnborough]

Power train braking also gives anti lock too as it'll not usually bring wheel to standstill like a caliper and disc.

Interesting. I never thought about this.

Honda were big time leaders of this in motorcycle racing, particularly as 4 strokes took the lead from two in moto-gp.

Rossi era is noted as how far they progressed this field, Rossi move to Yamaha is credited with taking that knowledge from rider perspective to there, and won the championship.

Initially with things like torque limiting clutch (ramp and cam to lift plates, opposite of lsd clamping) and running into engine mapping.
Gets into just how much torque to push into motor on overrun to assist deceleration, and how much is too much that it pushes the front. Sound familiar in SG quali off Australia.

[Snorked]

A small update from a recent Q&A:

https://car.watch.impress.co.jp/docs/news/1512436.html

What we are doing now is a single-cylinder engine, and we are testing combustion in the new geometry. We are also testing the V6 engine to see how it behaves in an engine without the MGU-H. Because the response becomes important if the turbo lag can not be covered by MGU-H, it becomes a form to supplement with MGU-K, but it is competitive if the torque characteristics can not be made well. It is because the power is gone.I think it would be nice if we could do 1:1 in the form of MGU-K and ICE, and coalesce as a power unit around the year.

- Had technical meeting with Aramco.

- Engineers responsible for current PU likely to return.

- Will decide soon with regards to European base, design and development remain focused in Japan.

[Wazari]

Looks like the long vacation (retirement) is over. Back to Sakura we go. I going to have to get a AMR cap soon.

[Roostfactor]

Looks like the long vacation (retirement) is over. Back to Sakura we go. I going to have to get a AMR cap soon.

You know me, I follow the Honda path! Looking forward to the crumbs you may leave us.

[DR30]

Looks like the long vacation (retirement) is over. Back to Sakura we go. I going to have to get a AMR cap soon.

Looking forward to the new journey but will be sad to see the current formula go.
Please keep us updated as you can, truly look forward to your insights.

[Wazari]

You know me, I follow the Honda path! Looking forward to the crumbs you may leave us.

Crumbs is all I have. Although I don't understand why Formula 1 is going this route with the new PU's, it does post many challenges. My focus as usual will be on the ICE combustion side. The first tasks ahead are making the new fuel work, working on lowering the compression and fuel consumption. I don't view turbo lag as being a future issue. I think the drivers will have a steep learning curve ahead of them with the characteristics of the new PU's. Going from approximated a 4:1 ICE to electric power ratio to almost a 1:1 ratio is a big change.