2013 Audi R8 e-tron
The Audi R8 e-tron demonstrates how emotional and dynamic electric mobility can be. Its two electric motors, supplied with energy by a large 48.6 kWh battery, develop 280 kW (380 hp) along with 820 Nm (604.80 lb-ft) of torque. They accelerate the high-performance sports car from 0 to 100 km/h (62.14 mph) in 4.2 seconds and to a governed top speed of 200 km/h (124.27 mph). The battery charge is good for an operating range of 215 kilometers (133.59 miles). Through the R8 e-tron, Audi has acquired extensive expertise that will benefit its electrified production models.
The Audi R8 e-tron weighs in at 1,780 kilograms (3,924.23 lb). Its body structure, including the side sections, weighs just 199 kilograms (438.72 lb), 23 kilograms (50.71 lb) less than that of the R8 Coupé, which already sets the bar very high with its aluminum-based ASF principle (Audi Space Frame). Here, Audi presents a new stage in the development of its ultra lightweight construction technology — a Multimaterial Space Frame, in which large parts made of carbon-fiber-reinforced polymer (CFRP) supplement the aluminum frame.
The CFRP components contribute 23 percent and the metal parts 75 percent of the bodyshell weight; miscellaneous materials make up the remainder. The forward structure of the R8 e-tron is a classic aluminum design. The dominant material in the occupant cell is CFRP, with the tail end using a blend of both materials. The supporting trunk insert of CRFP incorporates corrugated crash structures that mean the rear module can absorb five times as much energy as an aluminum lattice structure. For the B-posts and rear bulkhead, a new sandwich concept reduces the weight by 11.5 kilograms (25.35 lb).
Every single part of the outer skin, which is made almost entirely of CFRP, is tailored specifically to its position and purpose. In certain zones of the front lid, for instance, there are seven layers of carbon fiber matting one on top of the other. For the inner shells of the rear side sections, on the other hand, two layers incorporating nonwoven material are adequate.
The lithium-ion battery, too, is a reflection of the development expertise of Audi — it was designed and built in-house. Bolted to the structure at 40 points, it functions as a supporting element that more than doubles the rigidity of the Multimaterial Space Frame. The battery incorporates 530 prismatic flat cells. Taking the shape of a T, the battery is 235 centimeters (92.52 in) long, 135 centimeters (53.15 in) wide and, control unit included, 71 centimeters (27.95 in) high. Around the tunnel there are two floors with cell modules one above the other; at the rear end there are four floors.
Plates 12 millimeters (0.47 in) thick made from high-strength aluminum alloys separate the floors, while forming the battery’s supporting structure. The coolant circulates through narrow channels cut into these, with a total length of several hundred meters. A hydraulic distributor maintains a precisely calculated, smooth flow serving all cells equally.
The battery management system is housed together with the high-voltage switches and power fuses in the electrics box, which is located on the traction battery. The main tasks of the battery management system involve monitoring the battery system’s safety and, if need be, taking appropriate measures to prevent danger. It also determines the charge status and performance of the HV battery and transmits the readings to the electric motors’ drive controllers. To do that, the battery management system, for example, accesses a battery-internal network of cell electronics, to gage cell voltages and temperatures. If the battery’s charge level falls towards the threshold of 15 percent SOC (state of charge), the controller correspondingly reduces the amount of electrical power that can be taken from the battery. In addition, the functioning and safety of the high-voltage electrical system are permanently monitored; in the event of an accident, the battery is deactivated.
There are two options available for charging the battery: A full charge with 230-volt alternating current from the domestic mains takes about twelve hours. Charging with direct current cuts the time required to less than one hour, depending on the connected load. The driver can control and monitor a wide range of functions and information remotely by smartphone app, including the charge status, the interior heating and the range display. This is a customized service from Audi connect, which is also used in a very similar form in models such as the A3 Sportback e-tron.
The battery is also recharged while on the road by means of energy recovery during retardation phases. The driver chooses the degree of energy recovery in three stages (plus freewheeling) at paddles on the steering wheel.
Post time: Jun-11-2017