Magnetically coupled rotary magnetic encoder with angle error reduction

摘要

A rotary magnetic encoder assembly of noncontact or “contactless” construction having an internally disposed first exciter or sensor magnet magnetically coupled to an externally disposed second application or drive magnet attached to an encoder shaft that rotates the sensor magnet substantially in unison therewith during encoder shaft rotation. The sensor magnet is rotatively supported by a friction reducer that is a bearing arrangement that provides point bearing contact preventing stiction and reducing dynamic friction of the sensor magnet minimizing angle error and helping to prevent “Quiver.” In one embodiment, the friction reducer is a spherical ball bearing. In another embodiment, the friction reducer is a thrust bearing that includes a spindle carrying the sensor magnet. A magnetic anchor can be disposed between the sensor magnet and drive magnet to help keep the sensor magnet in point bearing contact during rotation further minimizing angle error.

主权项

1. A rotary magnetic encoder assembly comprising:
an encoder body or housing; a magnetic field sensor arrangement carried by the encoder body or housing; an interiorly disposed rotatable first magnet located adjacent the magnetic field sensor arrangement having a first magnetic field sensed by the magnetic field sensor arrangement when the first magnet rotates; a friction reducer in operable cooperation with the rotatable first magnet; a rotary encoder shaft carrying a second magnet for rotation substantially in unison therewith disposed adjacent the encoder body or housing having a second magnetic field magnetically coupling the first magnet rotating the first magnet during rotary encoder shaft rotation; and wherein the friction reducer is disposed between the first magnet and the second magnet.