Westfield Sportscars (westfield-sportscars.co.uk
) is a British-owned and –operated firm that hand builds sports cars. One of them, a Westfield Sport Turbo, has been transformed into a hybrid model that combines the 1.6-liter, 200-hp gasoline engine that drives the rear wheels with two 75-kW electric motors to drive the front—or at least provide a three-minute boost during a race.
A problem that Westfield needed to solve—and which Stephen Lambert, a research engineer at Warwick Manufacturing Group (www2.warwick.ac.uk/fac/sci/wmg
) took on—was how to keep the 396 lithium-ion phosphate cells that power the electric motors from overheating, because heat can sap the power and the available time of the batteries.
Lambert initially stored the cells in rows, side by side, in two battery boxes machined from solid plastic. A box would be dedicated to each motor. But then engineers from EOS (eos.info
), a producer of laser-sintering machines, suggested another solution: two arrays of 11 plastic modules; each module would accommodate 18 cells, each in its own cylindrical cavity.
They used an EOSINT P-series laser sintering machine to produce the modules with layers of fused EOS PA 2200 polyamide powder, based on data from a CAD model. By using this additive approach rather than machining, they were able to create air channels between each cell cylinder and between adjacent modules when they are bolted together. The consequent enhanced air cooling of the 3.6-volt cells helps boost the performance of the batteries and the electric motors.
According to Lambert, “By adding drive to the front wheels, we have managed to increase acceleration significantly. From a standing start, the Westfield Hybrid in four-wheel drive mode achieves 60 mph in 3.5 seconds, compared with 5.5 seconds when only the rear wheels are driven.”
The Westfield hybrid project is being jointly funded by the Warwick Innovative Manufacturing Research Centre and Potenza Technology (potenza.co.uk/technology/home.htm