Method and apparatus for cleaning a DC motor commutator-brush interface
First Claim
1. An apparatus for controlling the motion of a magnetic tape in a tape drive including a first reel assembly having a first motor for rotating in a first direction to supply a magnetic tape and for rotating in a second direction to take up the magnetic tape, a second reel assembly having a second motor for rotating in the first direction to take up magnetic tape supplied by the first reel assembly and for rotating in the second direction to supply magnetic tape to the first reel assembly, a first fine-line tachometer coupled to the first reel assembly, and a second fine-line tachometer coupled to the second reel assembly, said apparatus further including:
- a motor cleaning power supply producing an alternating polarity, adjustable current and variable frequency square wave;
a motor cleaning control unit connected to selectively supply the output current from said motor cleaning power supply to the first and second motors; and
means for activating said motor cleaning control unit to clean a brush-commutator interface of the motor connected to said motor cleaning power supply when the tape drive is otherwise inactive.
1 Assignment
0 Petitions
Accused Products
Abstract
Commutators on a direct current motor run at low speed for an extended period of time get covered with a coating that makes the interface between the commutator and the brushes unreliable especially with the low speed, low current operation. This is especially true for drive motors in a data processing tape drive unit where speed control is critical. The brush to commutator interface can be cleaned by applying a very high electrical current to the motor and varying the polarity of the current with a variable duty cycle to obtain the maximum cleaning currents in a relatively short time without dismantling the motors.
12 Citations
20 Claims
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1. An apparatus for controlling the motion of a magnetic tape in a tape drive including a first reel assembly having a first motor for rotating in a first direction to supply a magnetic tape and for rotating in a second direction to take up the magnetic tape, a second reel assembly having a second motor for rotating in the first direction to take up magnetic tape supplied by the first reel assembly and for rotating in the second direction to supply magnetic tape to the first reel assembly, a first fine-line tachometer coupled to the first reel assembly, and a second fine-line tachometer coupled to the second reel assembly, said apparatus further including:
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a motor cleaning power supply producing an alternating polarity, adjustable current and variable frequency square wave;
a motor cleaning control unit connected to selectively supply the output current from said motor cleaning power supply to the first and second motors; and
means for activating said motor cleaning control unit to clean a brush-commutator interface of the motor connected to said motor cleaning power supply when the tape drive is otherwise inactive. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A motor cleaning apparatus for cleaning a brush-commutator interface of a direct current motor without disassembling the motor comprising:
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a motor cleaning power supply producing an alternating polarity, adjustable current and variable frequency square wave;
a motor cleaning control unit connected to selectively supply the output current from said motor cleaning power supply to the motor; and
means for activating said motor cleaning control unit to clean the brush-commutator interface of the motor connected to said motor cleaning power supply. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for cleaning a brush-commutator interface of a direct current motor without disassembling the motor comprising:
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producing an electrical current having an alternating polarity, adjustable current and variable frequency square wave; and
applying the electrical current to the motor clean to clean the brush-commutator interface of the motor. - View Dependent Claims (18, 19, 20)
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Specification