October 9, 2003
NTN Develops Compact Reference Signal Sensor Bearing
NTN Corporation already markets an integrated sensor bearing that measures rotating speed and direction using a magnetic encoder built into a bearing. Now NTN has developed a compact "Reference Signal Sensor Bearing" with an additional new function to detect the reference position.
Electronic vehicle control systems are continuously becoming more sophisticated. Achieving optimum control of combustion in the engine will require accurate determination of the absolute crankshaft rotation angle. Likewise, the absolute angle of the steering wheel will be required for optimum performance of future power steering systems. Until now, detecting the absolute position required installing a separate large, bulky sensor or encoder outside of the integrated sensor bearing.
NTN's "Reference Signal Sensor Bearing" combines the rotational speed and direction sensor, with an encoder for detecting the reference or origin point. NTN has succeeded in making this combined unit the same compact size as the current "integrated sensor bearing" while adding the ability to detect the reference point. This allows detecting the absolute position of the shaft based on the reference position provided by the sensor.
Typical optical encoders have many drawbacks and limitations due to their mechanical structure and method of operation, including being unreliable under severe operating conditions involving vibration, heat and dust. NTN's "Reference Signal Sensor Bearing" uses a magnetic encoder and metal cover integrated into the bearing. The new NTN system works well even under extreme vibration, heat and dust and should prove ideal for new automotive applications.
Planning and Marketing Department, Automotive Sales Headquarters