Seat belt tension sensor

• US 6,578,432 B2
• Filed: 08/06/2001
• Issued: 06/17/2003
• Est. Priority Date: 06/19/2001
• Status: Active Grant

• Current Assignee: CTS Corporation
• Original Assignee: CTS Corporation
• Inventors: Blakesley, Patrick B., Rainey, Robert R., Broome, Randall, Kaijala, Murray, Lewis, John T.
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US09/923,151
• Publication Number:
  US 20020189365A1
• Time in Patent Office: 680 Days
• Field of Search: 738/26, 738/28, 324/207.26, 280/735, 280/801.1, 280/807, 340/667, 180/273, 180/268
• US Class Current: 73/826
• CPC Class Codes: B60R 2021/01272 Belt tensioners
• CPC Class Codes: B60R 21/0155 sensing belt tension
• CPC Class Codes: B60R 22/18 Anchoring devices
• CPC Class Codes: G01L 5/101 using sensors inserted into the flexible member
• CPC Class Codes: G01L 5/103 using sensors fixed at one end of the flexible member
• CPC Class Codes: G01L 5/108 for measuring a reaction force applied on a single support, e.g. a glider

Abstract

A seat belt tension sensor is attached to a seat belt in a vehicle. The seat belt tension sensor includes a housing attached between the vehicle and the seat belt. A limit structure is located in the housing. A sensor is attached to the limit structure for generating an electrical signal in response to the sensor being placed in tension. The electrical signal changes as a function of tension on the seat belt. The limit structure moves between a first position in which the limit structure transfers the seat belt tension to the sensor and a second position in which the limit structure transfers the seat belt tension to the housing.

Claims

1. A seat belt tension sensor for attachment to an anchor plate in a vehicle, the anchor plate having an aperture comprising:

a) a housing having a cavity and a cylindrical flange extending into the cavity, the flange having a hole therethrough;

b) a hub for receiving the anchor plate, the hub being located in the cavity and disposed over the flange;

c) at least one sensor attached to the hub, the sensor generating an electrical signal in response to the sensor being placed in tension, the electrical signal changing as a function of tension on the seat belt; and

d) a fastener extending through the hole of the flange and the hub for mounting the tension sensor to the vehicle, the hub moveable between a first position in which the hub transfers increasing seat belt tension to the sensor and a second position in which the hub transfers increasing seat belt tension to the housing.

2. The seat belt tension sensor according to claim 1, wherein the hub has a disc portion and a rim, the sensor located on the disc portion.

3. The seat belt tension sensor according to claim 2, further comprising a cover mounted to the housing and a plurality of springs located between the cover and the disc portion, the springs adapted to switch between the first and second positions.

4. The seat belt tension sensor according to claim 1, wherein the sensor is a strain gage resistor.

5. The seat belt tension sensor according to claim 2, wherein a plurality of strain gage resistors are located on the disc portion surrounding the rim.

6. The seat belt tension sensor according to claim 5, wherein the resistors are connected to form a wheatstone bridge.

7. The seat belt tension sensor according to claim 1, wherein the housing has a recess, the anchor plate passing through the recess.

8. A seat belt tension sensor for attachment to an anchor plate having an aperture for receiving a fastener for mounting to the seat belt tension sensor comprising:

a) a housing having a cavity and a cylindrical flange into the cavity, the flange having a hole therethrough;

b) a hub for receiving the anchor plate, the hub being located in the cavity and disposed over the flange, and having a disc portion, the disc having an attached rim;

c) at least one strain gage resistor attached to the disc, the strain gage resistor generating an electrical signal in response to the sensor being placed in tension, the electrical signal changing as a function of tension on the seat belt; and

d) the housing and the hub being positioned such that the fastener can extend through the hole and the hub for mounting to the vehicle.

9. The seat belt tension sensor according to claim 8, wherein the hub limits the strain on the resistor by engaging the housing in response to seat belt tension.

10. The seat belt tension sensor according to claim 9, further comprising a cover mounted to the housing and a plurality of springs located between the cover and the disc portion.

11. A seat belt tension sensor for measuring the amount of tension in a seat belt assembly in a vehicle, the seat belt assembly having an anchor plate that is attached to the vehicle with a fastener, the anchor plate defining an opening for receiving the fastener, the seat belt tension sensor comprising:

a) a limit structure located between the anchor plate and the fastener, the limit structure comprising;

a1) a housing having a cavity and a cylindrical flange extending into the cavity, the flange having a hole therethrough; and

a2) a hub for receiving the anchor plate, the hub being located in the cavity and disposed over the flange, the hole and the hub being aligned for receiving the fastener; and

b) a sensor mounted to the hub for generating an electrical signal in response to the seat belt being placed in tension, the hub moveable between a first position in which the hub transfers increasing seat belt tension to the sensor and a second position in which the hub transfers increasing seat belt tension to the housing.

12. A seat belt tension sensing device suitable for use with a vehicle connection bolt the device comprising:

a housing securable to the bolt for a seat belt assembly;

an apertured anchor plate slidably mounted to the housing, the anchor plate defining an opening for the bolt;

a strain gage secured to the housing;

a spring set between the anchor plate and the strain gage such that the strain gage is responsive to a force applied by the seat belt assembly to the anchor plate.

13. The seat belt tension sensing device according to claim 12 further comprising an actuator support set between the spring and the strain gage to actuate the strain gage.

14. The seat belt tension sensing device according to claim 12 wherein the housing includes a guide channel for receiving the spring.

15. The seat belt tension sensing device according to claim 12 wherein the anchor plate further defines a slot for securing a seat belt webbing.

16. The seat belt tension sensing device according to claim 12 further comprising a second spring set between the strain gage and the anchor plate, and an actuator slidably secured between the strain gage and both springs to actuate the strain gage.

17. The seat belt tension sensing device according to claim 12 including a stop to limit the sliding motion of the anchor plate such that the anchor plate is movable from positions in which increasing force of seat belt tension is detectable by the strain gage and a limit position in which increasing force of seat belt tension is countered by the stop.

18. The seat belt tension sensing device according to claim 17 wherein the stop is provided by a flange extending from the housing and received in the opening for the anchoring bolt.

19. The seat belt tension sensing device according to claim 17 wherein the opening in the anchor plate for the anchoring bolt is sized to provide limited sliding motion of the anchor plate with respect to the housing.

20. The seat belt tension sensing device according to claim 12 wherein the housing includes an extension transverse to the plane of the anchor plate and wherein a portion of the anchor plate abuts the projection when the seat belt tension exceeds a predetermined value.

21. The seat belt tension sensing device according to claim 12 wherein a projection is provided in an aperture of the anchor plate in the plane of the anchor plate for connection to the spring.

22. A seat belt tension sensing device suitable for use with a mounting bolt, the device comprising:

a housing securable to the bolt for a seat belt assembly;

an apertured anchor plate slidably mounted to the housing, the anchor plate defining an opening for the bolt and a cutout having a pair of opposing portions;

a spring set between the pair of opposing portions;

a strain gage secured to the housing and positioned between one of the opposing portions and the spring such that the strain gage is responsive to a force applied by the seat belt assembly to the anchor plate.

23. The seat belt tension sensing device according to claim 22 wherein the opposing portions are opposing sides of an opening defined by the anchor plate.

24. The seat belt tension sensing device according to claim 23 wherein at least one of the opposing portions includes a projection into the opening in the plane of the anchor plate for connection to the spring.

25. The seat belt tension sensing device according to claim 22 further comprising an actuator support set between the spring and the strain gage to actuate the strain gage.

26. The seat belt tension sensing device according to claim 22 wherein the housing defines a guide channel for receiving the spring.

27. The seat belt tension sensing device according to claim 22 wherein the anchor plate further defines a slot for securing a seat belt webbing.