Reduced speed growth in windshield wiper motor
First Claim
Patent Images
1. An electric motor in which brush seating occurs, comprising:
- a) brush means whichi) causes motor speed to increase during early stages of brush seating; and
ii) causes motor speed to decrease during later stages of brush seating.
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Abstract
In an ordinary DC motor in a windshield wiper, operating speed tends to increase as the motor brushes become seated. The invention counteracts this tendency by providing a brush geometry which causes the effective angular position of a brush to change during seating. The change is in a direction which tends to reduce speed.
44 Citations
8 Claims
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1. An electric motor in which brush seating occurs, comprising:
a) brush means which i) causes motor speed to increase during early stages of brush seating; and ii) causes motor speed to decrease during later stages of brush seating. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An electric motor, comprising:
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a) a commutator; b) brush means, which i) contacts the commutator, and ii) experiences brush seating as the motor operates, which causes A) motor speed to increase during initial stages of brush seating; B) motor speed to peak at about 40 percent of brush seating, at a peak speed of about 104.2 percent, or less, of motor speed at an initial brush seating, and C) motor speed to decrease after peaking, to a motor speed at full brush seating of about 102.3 percent, or less, of motor speed at initial brush seating.
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8. An electric motor, comprising:
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a) a commutator; b) a brush i) which contacts the commutator at a contact surface, A) of length 2×
ALPHA, andB) which is centered at a point which defines an effective brush angle, BETA;
wherein ALPHA is one-half the length of said contact surface and BETA defines said effective brush angles;ii) which wears during operation of the motor, causing ALPHA to increase, thereby tending to cause motor speed to change; and iii) in which the wear causes BETA to change in a manner which compensates for the change in ALPHA, thereby opposing the change in motor speed.
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Specification