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Bidirectional DC motor control circuit including overcurrent protection PTC device and relay

  • US 6,078,160 A
  • Filed: 11/20/1998
  • Issued: 06/20/2000
  • Est. Priority Date: 10/31/1997
  • Status: Expired due to Term
First Claim
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1. A motor position control arrangement for coupling between an electric power source and a bidirectional direct current electric motor for operating an apparatus, the power source having a positive output and a negative output, the motor having a positive input, a negative input, the apparatus having a full extended position and a full retracted position, the control arrangement comprising:

  • a. a control element, in use coupled in series with the motor, the control element comprising(1) an interrupt component having a closed state in which it can carry a normal circuit current and an open state in which it can carry at most a reduced circuit current, including no current, and(2) a sense component comprising means for sensing, when the motor rotates from one of the full extended position or the full retracted position to the other of the full extended position or the full retracted position, when the apparatus reaches said other position, and(3) a control component comprising means for changing the interrupt component from the closed state to the open state when the sense component senses that the apparatus has reached said other position;

    (4) the interrupt component and sense component being coupled as a series combination and the series combination being coupled in parallel with the control component, andb. a switch element, in use comprising(1) means for coupling(i) the positive output of the power source with the positive input of the motor, and(ii) the negative output of the power source with the negative input of the motor, and, alternatively(2) means for coupling(i) the positive output of the power source with the negative input of the motor, and(ii) the negative output of the power source with the positive input of the motor;

    wherein,A. with the apparatus in the full extended position, the interrupt component in the closed state, and the switch element coupling the positive output of the power source with the negative input of the motor and the negative output of the power source with the positive input of the motor, the motor rotating to move the apparatus to the full retracted position, wherein the control component, upon the sense element sensing that the apparatus has reached the full negative position, causing the interrupt component to change from the closed state to the open state, thereby removing power from the motor, andB. with the motor in the full negative position, the interrupt component in the closed state, and the switch element coupling the positive output of the power source with the positive input of the motor and the negative output of the power source with the negative input of the motor, the motor rotating to move the apparatus to the full extended position, wherein the control component, upon the sense element sensing that the apparatus has reached the fill extended position, causing the interrupt component to change from the closed state to the open state, thereby removing power from the motor.

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