As automation is becoming miniaturized, we see a demand to produce high-performance encoders to fit on, or in, smaller and smaller motors. Today our smallest “standard” encoder uses a 17.5 mm OD target wheel and is typically mounted on 20 mm stepper or servo motors.

 
Small:  Timken M9 encoder used a 17.5 mm OD target wheel.  Example is a 1,000 CPR (4,000 edges per revolution) A, B, Z off-axis magnetic encoder.

The off-axis design of the Timken M9 encoder allows customers to mount the encoder on the front or back of the motor and to have the shaft pass through the encoder to connect to the end user’s application. The M9 platform offers up to 1,000 CPR (4,000 quadrature signals per revolution) and a once per revolution index pulse. The M9 is also available with a differential line driver output to operate in harsh industrial environments.  

 
Medium:  Ring kit designed for a wide range of shaft sizes.  Notice the large diameter of the target magnet.

When your motor shaft is larger or you need higher resolutions, choose a larger encoder.  When a magnetic encoder gets larger, the sensor circuit does not need to change.  At Timken we typically use MPS160 or MPS512 sensor chips and add optional line drivers, connectors and application specific circuitry. The diameter of the target wheel changes to allow for more magnetic pole pairs and to extend outside the motor shaft diameter. The larger the sensing diameter the more resolution is possible, as well as more accuracy.

 

Large:  The sensor ring is mounted in a drive motor on a mining truck. Notice the size of the 17.5 mm M9 target fits well within the mining truck target wheel. Both applications use the same MPS160 sensor chip with slightly different settings.
 
For more information on what you need to know about magnetic encoders for your large or small motor, reach me at 603.358.4760 or send me at email at [email protected]. Please join our LinkedIn Group to continue the discussion.