Pierce89 wrote:The mgu produces negative torque through the geartrain even if the engine produces zero torque.
the MGU of itself can be regarded as producing positive torque to act as a motor, or negative torque to act as a generator
the current 60 kw limit corresponds to MGU torque of about 10% of max engine torque and about 2% of a brake torque equivalent
the lifted accelerator/overrun (negative) torque of a zero fuelled engine (engine braking torque) is around -20% of max engine torque
IMO any overrun fuelling is providing part or all the torque driving the generation from the MGU (compared with zero fuelling)
whenever overrun torque is raised as high as zero by fuelling all the MGU generation is powered by engine running, not by braking
because zero torque running gives all the torque (and more) required by the MGU for generation (compared with zero fuelling)
and the mechanical brakes will have to do more work (compared with zero fuelling)
fundamentally, any torque from overrun fuelling must (compared with zero fuelling) be absorbed by generation or braking
zeroing of overrun torque will exceed the torque required for generation whether or not gen torque is included in the definition
I admire the ingenuity of the engineers behind this (that's what the term once engineer meant)
generation at the MGU, by braking or otherwise, will be more difficult with much higher-powered systems in 2014