NL_Fer wrote: ↑16 Nov 2017, 00:32
I don’t think MGU-K is throttled. It is either on 120kw or off. Otherwise there is no 120kw reduction in power and the flashing rear light would not be triggered. It is just 120kw assist when throttle is floored, until the Ecu shuts it down or ES is depleted.
It is not set in the regulations that it must be 0 or 120kW, what is stated is the maximum is 120kW. The level of deployment through the MGU-K will be determined by the engine mode used, along with the amount of MGU-H recovery, and energy flow paths from MGU-H to ES and MGU-K. If there is limited capacity available in the ES then it makes sense to use MGU-K power at the beginning of the acceleration zone as the aero drag is much lower and you get better bag for your buck in terms of acceleration.
Remember that the MGU-K is bi-directional, providing positive torque under acceleration and negative torque under braking and perhaps during non-maximal driver torque demand (gen set). If then you take the regen under braking, there must be provision to modulate the negative torque applied by MGU-K to the engine during braking, a 0 or 120kW strategy would play havoc with brake balance.
NL_Fer wrote: ↑16 Nov 2017, 00:32
About ICE power: It could be possible that crankshaft power is comparable and that Mercedes gain is made in the amount energy that is generated in the exhaust gasses and recovered by MGU-H. We already know the engines are running extremly lean and take much more air than needed. Maybe it is just to expand/heat the air during combustion and recover this with MGU-H and use it for more deployment.
You can only recover a limited amount of energy from the MGU-K under braking, less than you can deploy under acceleration. This is because the cars are at WOT longer per lap than they are under braking and the limit is 120kW both ways. The remainder can be made up by MGU-H recovery, the problem is, the more thermally efficient your ICE is, the less is available for MGU-H. Running super lean has two benefits, one is that the expansion of the excess air helps pushing the piston and provides more gasses for MGU-H. Therein lies the main problem for Honda is that if the rumours that they can't get the TJI type ignition functioning as they would want, then the opportunity to run as lean as they would like is less.