Japanese automotive supplier NSK has demonstrated what it says is the first transmission-equipped wheel hub motor.
In-wheel motors have several advantages – they can reduce the weight of the vehicle, control the drive force of each wheel for improved torque vectoring, and possibly free up room for more passenger and cargo space.
However, achieving both the torque necessary for acceleration and hill climbing and a sufficient maximum speed requires a larger motor, which mitigates some of the advantages. In order to make in-wheel motors more compact, NSK developed its transmission-equipped wheel hub motor.
The module is equipped with two motors and a transmission composed of two planetary gears, which can achieve both high drive torque and a sufficient maximum speed with a small motor. The transmission also has a feature that enables smooth gear changing during acceleration by controlling the speed and torque of the two motors.
The company has demonstrated the technology using an experimental vehicle equipped with a prototype wheel hub motor, and now aims to commercialize components such as the hub unit bearing with built-in speed reducer, the one-way clutch unit, the miniature cage and roller bearing, and the anti-corrosion bearing.