Quote:
Originally Posted by JRMichler
Where is that on the engine performance map?
Would the energy conversion losses of a hybrid drive train be less or more than engine efficiency gains?
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Good question. On the last truck, and especially the new truck, we are
WAY OUTSIDE of the normal and supposedly optimal fuel map envelope. My thesis is that the many less combustion events per mile, more than make up for the theoretical advantage of running inside of the fuel map envelope. It seemed to work well on the last truck. Stay tuned for the results of the new truck. The Cummins X15 engine in the new truck will operate at 850 RPM at normal highway cruise speed, for most of the day. Redline is only 1100 RPM.
Good question again. The correct answer is less. We will be installing a hybrid electric axle on the tractor very soon. It will replace the 3rd dead "tag" axle on the rear of the tractor in our current 6x2 configuration. It is basically an E-Assist unit, where it will provide power during climbing grades and taking off from a standing start. Its dedicated battery will charge via regeneration while descending grades or otherwise coming to a stop. We anticipate a 15% gain from the hybrid axle. See earlier in this post where most of the fuel is used climbing grades.