Bridgestone Exhibits Updated Dynamic In-Wheel Drive System

Bridgestone has launched an improved version of its revolutionary in-wheel motor drive system for electric vehicles. First announced in September 2003, Bridgestone’s system was seen as an advance in in-wheel motor drive systems that use motors installed inside vehicle wheels.

Installing the drive motors inside the wheels allows for controlling each wheel individually, which supports excellent handling, Bridestone says. It also eliminates the need for the differential and drive shaft and therefore allows for unprecedented freedom when designing vehicles. Designers can allocate more space to the driver and passengers without increasing the overall size and weight of the vehicle.

One drawback of in-wheel drive motors has been the weight that they add to each wheel. That affects comfort and road-holding performance adversely, and it has limited the applicability of in-wheel motor systems in electric vehicles. Bridgestone claims to have employed dynamic damping to overcome this drawback of in-wheel drive systems. In this system, the motors themselves function as vibration dampers.

Their own vibration offsets the vibration from the road and tyres. That allows for better traction and a more-comfortable ride than are possible with other in-wheel drive systems or with other kinds of electric drive.

Now, Bridgestone has increased its lead in in-wheel motor drive systems by reducing the size and weight of its system, by enlarging the range of motor movement, and by increasing the system’s resistance to water and to dust. The company has developed several completely new components and mechanisms in support of these improvements. It has conducted that development work in cooperation with Kayaba Industry Co., Ltd., and Akebono Brake Industry Co., Ltd. Bridgestone has been working with those two partners since 2000 on modular systems for vehicle suspensions. With an eye to commercialising its dynamic-damping in-wheel system, Bridgestone is also developing tyres and other peripheral components to optimise the system’s performance.