Importance

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Abstract

A testing apparatus for rotors of electric motors comprising a test fixture including a fixture shaft on which a rotor is temporarily attached to a known inertial load. A stator creates a rotating magnetic field to cause rotation of the rotor, and an encoder senses the amount of angular rotation of the rotor in short time intervals, which is recorded in a memory and later used to calculate torque. An index mark from the encoder indicates each complete revolution of the rotor and may be used to determine the location of a defective rotor segment by reference to a start point mark placed on the rotor prior to the test. An electronic control circuit initially applies a low value electric current to the stator to create a rotating magnetic field to cause the rotor to rotate at a slower than normal rate to improve the resolution of the torque measurement. After the rotor has accelerated to a predetermined value, the stator voltage may be increased. The amount of actual rotation of the rotor at multiple, known time intervals as the rotor accelerates to a predetermined speed is used to calculate actual torque.

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First Claim