InEco EV's steel-CFRP hybrid construction keeps weight under a ton
By C.C. Weiss
October 21, 2013
One of the quieter debuts at last month's Frankfurt Motor Show was also one of the more interesting. The InEco electric car, developed at the Dresden University of Technology's Institute of Lightweight Engineering and Polymer Technology (TU Dresden's ILK), combines an innovative mix of materials to keep its weight down to under a ton and allow it to get the most out of its small electric powertrain.
InEco is an ongoing project by TU Dresden and several corporate partners, including Leichtbau-Zentrum Sachsen GmbH and ThyssenKrupp AG. At Frankfurt, the parties presented the first roadworthy demonstrator model, an urban-focused, four-seat hatchback.
The focus of the InEco project has been on experimenting with construction methods and material blends. The body and chassis of the car are built with a variety of materials, most notably steel and carbon fiber-reinforced polymer.
In using steel construction to augment and reinforce the CFRP, the InEco combines the advantages of both – the non-splintering malleability of steel, advantageous in crash protection, and the light weight, rigidity and high energy absorption of CFRP. Some structures are made strictly from steel, some from CFRP, some from a mix of both materials, and some from other materials like aluminum. The diagram below shows the different materials (in German) in use around the car's structure.
According to TU Dresden, the steel-CFRP hybrid construction has allowed for the simplification of the car's design, cutting 70 percent of traditional bodywork components out. The research vehicle weighs just 1,984 lb (900 kg), including a 330-lb (150-kg) chassis, batteries and electric powertrain. That low weight allows a modest combination of 120-hp synchronous motor and 15 kWh lithium-ion battery pack to push the four-seat hatchback to 62 mph (100 km/h) in 7.5 seconds and on to a top speed close to 100 mph (160 km/h). The 100-cell battery pack keeps firing for around 75 miles (120 km) of driving distance.
Those performance numbers don't sound all that different from current-generation electric vehicles, but the battery pack is smaller than average thanks to the car's low weight. For comparison, the Nissan Leaf uses a 24 kWh battery pack; the Ford Focus Electric uses a 23 kWh battery; and the Chevy Volt, a gas-electric hybrid, uses a 16.5 kWh battery.
Styling is often a distant afterthought when it comes to a technological research vehicle, but the InEco does manage to catch the eye with its Hyundai Veloster-like hot hatch look that comes courtesy of its sharp headlamps, descending roofline and wraparound-style glasshouse.
While the InEco isn't likely to show up in dealerships anytime soon, some of the methods used in its construction may influence the automotive industry.
Source: TU Dresden
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