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Abnormally detecting device for relay

  • US 5,568,025 A
  • Filed: 10/26/1994
  • Issued: 10/22/1996
  • Est. Priority Date: 11/02/1993
  • Status: Expired due to Term
First Claim
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1. A device for detecting an abnormality in relays for driving a motor selectively in both forward direction and a reverse direction, comprisinga power supply;

  • a motor driving portion including a first switching element for forward rotation, a second switching element for backward rotation, a first motor driving relay for forward rotation operated in response to turning-on of said first switching element, and a second motor driving relay for backward rotation operated in response to turning-on of said second switching element, said motor driving portion passing current from said power supply through said motor in directions of the forward and backward rotations by operation of said first and second relays, respectively, to drive said motor;

    an input portion for providing a forward rotation command and a backward rotation command;

    a controller for outputting a switching control signal to said first and second switching elements in response to said forward and backward rotation commands, respectively; and

    a signal detecting portion for detecting current through said motor to output a detection signal to said controller,wherein said controller senses said detection signal indicating a current flow through said motor when said first and second switching elements are off, thereby detecting an abnormality in said motor driving relays, and said controller turns on said first and second switching elements by outputting said switching control signal to said first and second switching elements to provide the same potential across said motor.

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