Bridgestone first released details of the in-wheel motor system in September 2003. Then, a more compact and lighter version was designed in September 2004. Based on this technology, Bridgestone developed the latest version especially for small tyre sizes.
Installing the drive motors inside the wheels means each wheel can be controlled individually, which supports excellent handling. It also eliminates the need for the differential gear 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.
On the other hand, a stubborn drawback of in-wheel 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 says it has employed innovative dynamic dampers to overcome this drawback.
The latest version of in-wheel motor system uses an inner rotor type motor as opposed to an outer rotor type motor, while making improvements to several key components to realise a better system that is lighter and more compact than its predecessors.
Bridgestone conducted its development work in cooperation with KYB Corp. and Akebono Brake Industry Co. Bridgestone has been working with those two partners since 2000 on vehicle suspension module. With an eye to commercialising its dynamic-damper type in-wheel system both versions two and three of its system, Bridgestone continues refining Bridgestone Dynamic-Damper type In-Wheel Motor System. Bridgestone is also developing tyres and other peripheral components to optimise the system’s performance.