January 25, 2008
NTN Develops a compact planetary roller screw type electric brake actuator
NTN Corporation has developed a durable. lightweight, compact, planetary roller-screw type actuator for tomorrow's electric brake systems.
Brake by-wire technology is the next generation brake system and is a prime component providing greater improvements in vehicle stability systems. NTN has developed a new planetary roller screw electric brake actuator for high-end performance. This design is comprised of a compact independent linear motion mechanism combined with a planetary roller screw, and an electric motor. This linear motion mechanism is able to generate pad pressure without a speed reduction mechanism by means of friction transmission between the sun roller and planetary roller. The pressure required for friction transmission to the planetary roller screw mechanism is designed to have no endplay or allowable lash. This design results in zero wear from vehicle vibration and provides greater durability. It is also possible to apply braking force during a vehicle stop with the loss of supply of electricity to the motor.
This actuator was exhibited at the Tokyo Motor Show in October 2007.
|a.||Light weight and compact design|
|An independent planetary roller screw is used as a brake mechanism. Speed reduction mechanism with a high reduction ratio, that is required for ball screw type or ball ramp type, is unnecessary.|
|No endplay in the planetary roller screw mechanism prevents micro wear due to vehicle vibration.|
|c.||Brake force retention function|
|Brake force is assured without supplying electricity to the motor.|