Seat belt tension sensor
First Claim
Patent Images
1. A seat belt tension sensor comprising:
- a bracket adapted to be attached to a structural number of a passenger vehicle, the bracket having portions defining an opening through which a seat belt is looped, wherein the bracket has a seat belt restraining side;
a carriage positioned within the bracket opening and movable toward the restraining side;
a magnetic field sensor mounted on the restraining side of the bracket;
a magnet mounted on the carriage for motion toward the sensor mounted on the restraining side; and
at least one spring positioned between the carriage and the restraining side, biasing the carriage away from the restraining side, wherein the carriage moves toward the restraining side when tension is applied to the seat belt.
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Abstract
A sensor of Giant magneto-resistive (GMR) type is attached to a seat belt anchor bracket. A seat belt passes through an opening in the bracket and is doubled back and sewn to form a loop. A magnet positioned on a sliding carriage is biased away from the sensor by springs. A seat belt loops around the carriage, and when tension is applied to the belt, the carriage with the magnet is drawn against the springs toward the GMR sensor. The GMR sensor measures the magnetic field present at the sensor and a microprocessor determines belt tension based on the known spring constants and the strength of measured magnetic field which is correlated with displacement of the magnet.
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Citations
15 Claims
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1. A seat belt tension sensor comprising:
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a bracket adapted to be attached to a structural number of a passenger vehicle, the bracket having portions defining an opening through which a seat belt is looped, wherein the bracket has a seat belt restraining side; a carriage positioned within the bracket opening and movable toward the restraining side; a magnetic field sensor mounted on the restraining side of the bracket; a magnet mounted on the carriage for motion toward the sensor mounted on the restraining side; and at least one spring positioned between the carriage and the restraining side, biasing the carriage away from the restraining side, wherein the carriage moves toward the restraining side when tension is applied to the seat belt. - View Dependent Claims (2, 3, 4, 5)
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6. A seat belt tension sensor comprising:
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a bracket adapted to be held fixed relative to a structural member on a passenger vehicle; a belt retaining portion of the bracket; a magnetic field sensor mounted on the bracket; a carriage mounted on the bracket for movement toward and away from the sensor; a means for biasing the carriage away from the bracket; and a magnet mounted on the carriage so that motion of the carriage against the means for biasing moves the magnet toward the sensor. - View Dependent Claims (7, 8, 9, 10)
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11. A seat belt tension indicating apparatus comprising:
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a means for detecting and transmitting information about magnetic field strength; a magnet; a means for positioning the magnet spaced from the sensor; a means for biasing the magnet away from the sensor; and a means for attaching a seat belt to a passenger vehicle so that tension on the seat belt moves the magnet and sensor closer together. - View Dependent Claims (12, 13, 14, 15)
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Specification