Bearing failure indicator for rotating electric machines
AssigneeTexas Eastern Scientific Research, Inc.
InventorsLarry E. Hubbard, Clifford A. Rhorer
Life of this patent
Estimating the term…
Abstract
In a squirrel cage type of induction motor, conductive strips insulated from the stator are circularly spaced, ninety degrees apart, and project 0.003 inches into the rotor-to-stator clearance space. Upon excessive lateral rotor movement, it contacts a strip, closing a low voltage circuit triggering an alarm and de-energizing the motor. A reset button must be pressed to enable starting the motor.
Claims7
In an electrical machine having a stator which is generally symetrical about an axis, and a rotor coaxial with the stator, with a plurality of pole portions on the stator, the improvement comprising:
- sensor means having a fixed position relative to said stator and including a contact portion operable as a circuit switch contactor in response to radial movement of said rotor relative to said stator;
- a source of electrical energy;
- electronic switch means having a control element in series circuit relationship with said contact portion and said rotor and said source in a sensor circuit, said contact portion and said rotor serving as a normally-open sensor switch whereby said sensor circuit is non-conducting when said rotor is not contacting said contact portion, but conducting when said rotor contacts said contact portion;
- a relay including an operator coil in series circuit with said source and a load circuit path of said electronic switch means, and said relay including relay contactor means operable by said coil responsive to conduction of current through said load circuit path and coil to operate said contactor means;
- and
- an indicator circuit including an indicator and a normally-open contact portion of said relay contactor means, for energizing said indicator in response to said operation of said contactor means by said relay coil.
A method of sensing impending stator contact by a co-axial rotating rotor of an electric motor comprising the steps of:
- placing sensor means in the circular space between the rotor and stator;
- applying a sensor circuit voltage across the space between the rotor and sensor means;
- using contact of the rotor with the sensor means as a switch closing a sensor circuit to establish a current in the sensor circuit;
- and using current in the sensor circuit to energize annunciator means.
Dependencies are inferred from the claim text.