Last year saw the world premiere of the “Light Car” which, with its innovative exterior design and novel lighting concept, is an independent design concept for the electric-powered car of the future.
Presented for the first time ever at the 2010 Geneva Show, EGAG has combined the latest in lightweight materials, semi-finished products and advanced joining concepts in a space frame structure. The initial aim was the development of a scaleable platform for small to medium volumes, involving minimal investment costs for tools and manufacturing equipment, and not exceeding an overall weight of 1,200 kg (including a battery pack to cover a range of 150 km or 93 miles).
The Drive System
The drive system of the EDAG Light Car – Open Source consists of two of our open source partner Protean Electric’s wheel hub motors mounted in a double wishbone rear axle. Each weighing 30 kg, the wheel hub motors provide more flexible design options, as they take up less space than the conventional engine and drive train, both of which have been eliminated. An alternative option is a drive system with motors positioned centrally on either the front or rear axle.
The wheel hub motors are powered by 180 Gaia battery cells featuring lithium iron phosphate technology (3.2 V; 122 Wh; 1.5 kg). Compared to lithium-ion battery engineering, this technology offers enhanced safety properties with regard to thermal and mechanical damage. The battery capacity of 22 kWh gives the driver of the EDAG “Light Car – Open Source” a maximum range of 150 kilometers (93 miles) and a top speed of 140 km/h (87mph). Using the charger developed by EDAG and a charging rate of 10 kW, recharging takes approximately 2 hours.
One further specialty the EDAG development team came up with for the “Light Car – Open Source” is active rear axle steering. This type of steering enables the yaw rate amplification factor to be adjusted, making it possible to achieve greater agility at low speeds and improved vehicle stability at higher speeds. In addition, the reduction of the car’s turning radius leads to improved driving comfort.
The Space Frame
A combination of steel, aluminum and fiber composites was selected to construct the space frame structure. This guarantees not only adequate energy absorption by crash-relevant structure components, but also maximum stability at the lowest possible weight, and the best possible protection for passengers and the battery in the event of a collision, according to EDAG.
Laser-welded and partially hardened sections made of extremely high performance steel were used in the floor, door sill, A-pillar and front end areas.
High-strength, thin-walled aluminum structural cast parts produced by Honsel, light metal processing specialists, were used for the structural nodes at the rear and in the B-column of the EDAG Light Car – Open Source.
The need for thin-walled cast steel body components was met through the involvement of CX-Gruppe, a company specializing in casting technology. The application of thin-walled, high-strength cast steel spans the front structural nodes, floor, door sill and the integral suspension strut domes. This means that it might soon be possible to make ribbed and topologically optimized cast parts in high-performance body structures out of steel, something which was previously limited to aluminum cast parts.
The space frame structure is covered with a type of lightweight plastic outer skin panels and already produced by EDAG as Class A-type “HT PU RIM components” for low-volume series. With a minimum of capital expenditure and using polyurethane technology, EDAG says, it is possible to bring about weight-optimized exterior skin components that can be used economically in low-volume series, while providing a high degree of design freedom.
The results meet not only the target weight (limited to a maximum of 1,200 kg), but also all the current requirements of modern car bodies.[source: EDAG][wzslider height=”400″ lightbox=”true”]