Urbee 2, the first road-ready, fuel-efficient car built using 3D printing, is the subject of a collaboration between design firm KOR EcoLogic, direct digital manufacturers RedEye On Demand, and 3D-printing manufacturer Stratsys. Their aim is to put the 7 hp (5 kW) three-wheeled, rear-steering eco-hybrid on the roads by 2015, and then demonstrate its capabilities by crossing the US using only ten gallons (38 L) of fuel.
The first Urbee, introduced in 2010, combined a fuel-efficient 5 hp (3.8 kW) hybrid drive and a 3D-printed body with excellent aerodynamic performance to achieve over 200 mpg on the highway. However, the original 3D-printed body was made using a great deal of excess material to produce strength without the benefit of careful designing. The safety of the car in a crash was also questionable. As a result, the Urbee was a successful concept car, but stopped there.
Stopped, that is, until the Urbee 2 came along. Urbee 2 shares the same general design, being a three-wheeled two-seater that is steered by a single wheel in the rear of the vehicle. It will weigh about 1,200 lbs (550 kg), some thirty percent less than the original Urbee.
Urbee 2 is a series-parallel hybrid vehicle, meaning it combines more than one energy source to propel the vehicle. In the city, the Urbee runs on electricity stored in its batteries, which are expected to store about 10 hp-hours (7.6 kWh). The front wheels are driven by a pair of 36 volt electric motors, which together provide a cruising power of 8 hp (6 kW) and a peak power of 16 hp (12 kW).
The kinetic energy of the vehicle is largely recovered by a regenerative braking system and stored in a set of ultracapacitors with a capacity of about 0.05 hp-hour (35 W-hr). The pure electric driving range is likely to be in the neighborhood of 40 miles (64 km). Should the batteries start to die during the commute home, an internal combustion engine will run an alternator to charge them.
At highway speeds, Urbee utilizes an internal combustion engine, as such an engine is most efficient when running at about 60 percent of its peak power. This powertrain will allow the Urbee 2 to cruise comfortably at about 70 mph (110 km/h). Although an engine has not yet been selected, it is likely to be a 7-8 hp single-cylinder diesel which can also be run on ethanol. Roughly speaking, this is a very efficient lawnmower engine. When passing or on uphill stretches, additional power is obtained by operating the electric and diesel engines in parallel.
Source: Gizmag
