NTN to mass produce in-wheel motor for electric cars

NTN Corp., one of Japan’s largest manufacturers of bearings, will start mass-producing an in-wheel motor for electric vehicles as early as 2012, which will make it the first firm to do so. The in-wheel motor, which is attached to the back of a wheel, moves the tire directly. The challenge had been the weight, as four such motors weighed about 150 kilograms in total, making them impractical. But the company overcame the problem by using air instead of water to cool the motor, a change that led to a smaller number of required parts. As a result, the prototype’s weight has been reduced by about 30%. The major advantages of the innovative device are that because it can move tires directly, parts used to transmit power, such as the axle and gears, are no longer necessary and the car loses less energy. The motor also increases maneuverability, allowing the car to turn on the spot and move sideways, due to a widened turning angle. It can withstand driving 300,000 kilometers, according to the developer. Mass production is expected to begin at an R&D base in Iwata, Shizuoka Prefecture. (May 18, 2010)