Hybrid Electric Powered Axle
A 6×4 chassis can now have both an engine driven axle and an electrically driven axle. The regenerative braking can not only save on brake wear, the energy can be captured in situations where additional power is beneficial such as vehicle launch or steep/lengthy inclines to decrease fuel consumption. Effectively the vehicle is a 6×2 when normal efficient operation is desired and becomes a 6×4 when it is most beneficial.
Benefits
Fuel Savings
Available Power
Challenges
Weight
Cost
Introduction & Rationale
Formula One race cars utilize regenerative braking as do numerous models of electric and hybrid passenger cars. An electric drive axle is used for the rear tractor axle in this strategy. During downhill runs and during braking situations, the axle powers an electric motor-generator which stores the generated electric power in a lithium ion battery pack. When appropriate for power to be applied via this axle the process is reversed to keep the diesel engine operating most efficiently.
Available Systems
A few suppliers have developed electric axles and these systems are now in validation. One supplier provides a complete solution which combines their electric axle with the battery, an electric AC system and the controlling software.