|The hybrid conversion concept. Click to enlarge.|
A pair of Australian inventors have developed a concept for a retrofitted electric drive unit to convert conventional heavy-duty transport vehicles to plug-in hybrids.
The retrofit concept uses a bogie axle drive to create a through-the-road hybrid drive that can reduce fuel consumption up to 25%, by the inventors’s estimates.
This would fast track the introduction of hybrid vehicles onto our roads by utilizing the existing fleet...We expect the conversion unit to pay for itself in the first year of use by way of the reduced fuel consumption. We have secured a patent pending to entice investors so as to start producing this concept.—Clifford Hall
|Main components in the conversion. Click to enlarge.|
One mode of conversion is to reverse the positions front to back of a typical two-axle bogie drive unit and to discard the connecting jack shaft. This allows the installation of two electric motors to the former front-drive axle (now in the rear), utilizing the power divider unit.
Converting trucks with a single drive axle and a trailing, non-drive load sharing axle would require either the purchase of another single drive axle to replace the lazy axle or the purchase of a bogie front-drive axle to replicate the other mode of conversion with twin electric motors.
The Halls use UQM HPM150 brushless PM motor/generators for reference. The UQM units offers 150 kW (200 hp) power peak, with peak torque of 650 Nm (480 lb-ft). The inventors envision using a combination of lithium-ion batteries and supercapacitors for optimum performance. The Li-ion pack will be grid-chargeable.
Proposed modes of operation for the hybrid vehicles include:
Truck leaves terminal with fully grid-charged batteries.
Acceleration using combination diesel and electric assistance.
Highway cruising using diesel only and cruise control.
Hill climbing, cruise control engages electric assistance to maintain road speed. Diesel rpms and throttle position remain static.
Down hill, regenerative braking slows the vehicle and recharges the batteries. Diesel engine rpms remain low, no over revving. Braking also recharges batteries and saves brake wear.
Quiet mode, electric assist is engaged to maintain road speed while diesel engine only idles. It is for travelling slowly through towns to reduce noise pollution.
A working prototype has not yet been built.