SKF has released sensor-bearing units that ascertain the precise motion status of rotating or axially travelling components in open-loop and closed-loop motion control systems. They can record the number of revolutions, speed, direction of rotation, relative position/counting, and acceleration or deceleration.
They offer a uniformly high signal quality, minimal liability to interference, and insensitivity to vibration or high temperatures. Applications include electric motors, linear actuators, steering systems, conveying and handling systems and automation equipment. They can serve as viable alternatives to incremental encoders.
Their simple, lightweight and robust construction integrates an SKF Explorer class single-row deep groove ball bearing with an SKF active sensor. The unit's ball bearing can perform at high speeds, accommodate radial loads, locate the shaft axially in both directions, and is sealed for protection and relubrication is not needed for its intended life.
The active sensor (shielded to protect against external electromagnetic influences) consists of a magnetised impulse ring attached to the inner ring of the unit, a sensor body with Hall sensors carried by the outer ring, and a connecting cable.
In operation the bearing unit's impulse ring moves past the stationery sensor ring when the inner ring rotates, generating a magnetic field of changing polarity. The sensor outputs a pulse, based on number of polarity changes per second. The sensor output signal is then transmitted via connecting cable to generate the required application-specific information. Speeds down to zero can be recorded.
SKF sensor-bearing units are available in a wide range of bore sizes and dimensions. Customised units can be developed to meet specific customer requirements.