Hall effect seat belt tension sensor

• US 6,729,194 B2
• Filed: 07/25/2002
• Issued: 05/04/2004
• Est. Priority Date: 07/25/2002
• Status: Expired due to Fees

• Current Assignee: CTS Corporation
• Original Assignee: CTS Corporation
• Inventors: Teeters, Dale, Kaijala, Murray
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): MACK, COREY D
• Application Number:
  US10/202,727
• Publication Number:
  US 20040016304A1
• Time in Patent Office: 649 Days
• Field of Search: 738/626.9, 737/63, 737/74, 737/79, 738/623.91, 738/011, 737/35
• US Class Current: 73/862.69
• CPC Class Codes: B60R 21/0155 sensing belt tension
• CPC Class Codes: B60R 22/18 Anchoring devices

Abstract

A hall effect seat belt tension sensor for a vehicle. The sensor has a housing mounted to a seat belt. An anchor plate is mounted between the seat belt and a fixed point on a vehicle. The anchor plate is partially mounted in housing. A spring is mounted between the housing and the anchor plate. Tension on the seat belt causes the anchor plate to move relative to the housing. A magnetic field generator is mounted to the anchor plate. The magnetic field generator moves as the anchor plate moves. A magnetic field sensor is mounted to the housing. The sensor generates an electrical signal in response to movement of the magnetic field generator.

Claims

1. A seat belt tension sensor that is attachable between a seat belt and a vehicle structure comprising:

a) a housing having a cavity;

b) a fixable anchor plate having a first portion located in the cavity, the anchor plate further having a cutout, the housing movable relative to the anchor plate between a first position and a second position;

c) a magnet mounted in the cutout;

d) a movable sensor mounted to the housing, the sensor generating an electrical signal in response to moving between the first and second positions, the electrical signal changing as a function of tension on the seat belt; and

e) a spring located between the housing and the anchor plate, the spring urging the housing toward the first position.

2. The seat belt tension sensor according to claim 1, wherein a carriage is mounted in the housing and the magnet is mounted in a magnet carrier, the magnet carrier being slidably supported by the carriage, the magnet carrier located in the cutout.

3. The seat belt tension sensor according to claim 2, wherein the magnet generates a variable magnetic field.

4. The seat belt tension sensor according to claim 3, wherein the magnet is tapered.

5. The seat belt tension sensor according to claim 2, wherein the sensor is a hall effect device.

6. The seat belt tension sensor according to claim 5, wherein a wire harness is attached to the sensor and extends from the housing.

7. The seat belt tension sensor according to claim 2, wherein the carriage is mounted over the sensor.

8. The seat belt tension sensor according to claim 1, wherein the anchor plate has a first and second aperture, the cutout located between the apertures.

9. The seat belt tension sensor according to claim 8, wherein a fastener passes through the second aperture and is affixed to the vehicle structure.

10. The seat belt tension sensor according to claim 9, wherein the seat belt passes through the first aperture.

11. A seat belt tension sensor for that is attachable between a seat belt and a vehicle structure comprising:

a) a housing having a cavity and an apertured flange;

b) an anchor plate having a cutout and a first and second aperture, the anchor plate at least partially mounted in the cavity, the apertured flange extending through the second aperture, the housing movable relative to the anchor plate;

c) a carnage mounted to the housing;

d) a magnet mounted in the cutout adjacent the carriage, the magnet moving as the anchor plate moves, the magnet further being guided by the carriage; and

e) a magnetic field sensor mounted to the housing under the carriage, the carriage protecting the magnetic field sensor, the sensor generating an electrical signal in response to movement between the housing and the anchor plate, the electrical signal changing as a function of tension on the seat belt.

12. The seat belt tension sensor according to claim 11, wherein a spring is located between the housing and the anchor plate.

13. The seat belt tension sensor according to claim 11, wherein the magnet is mounted in a magnet carrier, the magnet carrier being slidably supported by the carriage.

14. The seat belt tension sensor according to claim 11, wherein the magnet is tapered.

15. The seat belt tension sensor according to claim 11, wherein the magnetic field sensor is a hall effect device.

16. The seat belt tension sensor according to claim 11, wherein a fastener passes through the first aperture and is affixed to the vehicle structure.

17. The seat belt tension sensor according to claim 11, wherein the seat belt passes through the first aperture.

18. The seat belt tension sensor according to claim 11, wherein a printed circuit board is mounted in the housing, the hall effect device mounted to the printed circuit board.

19. A seat belt tension sensor comprising:

a) a housing that is adapted to be mounted to a seat belt, the housing having an aperture;

b) an anchor plate that is mountable between the seat belt and a fixed point on a vehicle, the anchor plate having a cutout and further being partially mounted in the housing;

c) a spring set between the housing and the anchor plate, tension on the seat belt causing the spring to be compressed and the housing to move relative to the anchor plate;

d) a magnetic field generator supported in the cutout; and

e) a magnetic field sensor mounted to the housing adjacent the magnetic field generator, the magnetic field sensor moving in response to an applied tension on the seat belt, the magnetic field sensor generating an electrical signal that is proportional to the applied tension.

20. The seat belt tension sensor according to claim 19, wherein the anchor plate has a first and second aperture, the seat belt attachable through the first aperture.

21. The seat belt tension sensor according to claim 20, wherein a fastener is attached through the second aperture to the fixed point.

22. A seat belt tension sensor comprising:

a) a housing that is adapted to be mountable to a seat belt, the housing having an apertured flange, the housing adapted to be secured to a vehicle;

b) an anchor plate having a cutout, a first aperture and a second aperture, the apertured flange extending through the second aperture, the anchor plate being partially mounted in the housing, the first aperture adapted to be attachable with a seat belt;

c) a spring set between the housing and the anchor plate, tension on the seat belt causing the spring to be compressed and the anchor plate to move relative to the housing;

d) a magnet supported in the cutout;

e) a carriage mounted to the housing, the magnet slidably supported by the carriage; and

e) a magnetic field sensor mounted to the housing under the carriage, the magnetic field sensor generating an electrical signal that is proportional to the magnitude of tension applied to the seat belt.