saviour stivala wrote: ↑
Sun Apr 21, 2019 6:38 pm
The driver throttle/accelerator pedal demand (movement/travel 0 to 100) is fulfilled by a mix of electrical (through MGU-K) and ICE power/torque output, the level and mix of which depends on the mapping selected by said driver from on the steering wheel.
This mix of electrical and ICE power/torque output is delivered to the driven wheels through the crankshaft because the MGU-K is geared to the crankshaft at a ratio of 3.333;1, which means that when the crankshaft is rotating at max power speed of 10500rpm the MGU-K is rotating at 35000rpm outputting its max power/torque to the crankshaft.
Now as far as I know regardless of the interpretations, and regardless of the mix of electric/ICE power/torque map selected, the driver throttle/accelerator pedal travel (0 to 100 travel) controls the crankshaft RPM through the ICE throttle/s butterflies travel (0 to 100 travel).
Will repeat that, (1) the rules makes 2 exceptions to this driver throttle/accelerator pedal travel and the ICE throttle butterflies opening (travel) relationship. And (2) if said pedal/butterflies travel relationship wasn’t there the teams would be able to open a can of worms to ply with.
Well, first of all the Gear ratio between the MGU-K and the Crankshaft isn't writen down in the rules. There are maybe teams which use a gear ratio of 3.333:1, but i think nobody here knows if all teams really do that. Yes, in theorie a 3.333 ratio would you allow to rev the ICE up to 15000rpm. But here's the thing, nobody revs that high.
What you control with a throttle pedal, regardless if drive by wire or not, is not the rpm of the engine. It's solely the torque output. Any rpm gain or loss is the result of increasing/decreasing torque.
And as so many already wrote before, with a drive by wire system, the driver has no direct control over the butterfly valves/throttle bodies. The electronics decide how to achieve the demanded torque output in the fastest and/or most efficient way possible. It's possible that the electronics opens the throttle more to achieve this, but it doesn't necessarily has to. For instance what could happen if you move the pedal rapidly from 0 to 70% and then keep it there? Well, i would expect that they use the full power of the MGU-K initially and then dial it back because of the limited energy the MGU-K has. But what does this mean mechanically? Well, when you dial back the MGU-K you need more torque from the ICE which potentially means the butterfly valves move although you keep the pedal at exactly 70% all the time.