Seat belt tension sensor, methods of integration and attachment

• US 6,566,869 B2
• Filed: 06/04/2002
• Issued: 05/20/2003
• Est. Priority Date: 05/04/2000
• Status: Expired due to Fees

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Chamings, Antony W., Grzic, Rudi, OʼNeill, John
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): PATEL, PARESH H
• Application Number:
  US10/161,926
• Publication Number:
  US 20020145422A1
• Time in Patent Office: 350 Days
• Field of Search: 246/33, 324/207.11, 324/207.24, 324/207.26, 738/625.82, 738/659, 701/45, 280/801.1, 280/802, 280/804, 280/806, 280/735
• US Class Current: 324/207.26
• CPC Class Codes: B60R 2022/1806 for buckles
• CPC Class Codes: B60R 2022/4841 for sensing belt tension
• CPC Class Codes: B60R 21/01544 detecting seat belt parameters, e.g. length, tension or height-adjustment
• CPC Class Codes: B60R 21/0155 sensing belt tension
• CPC Class Codes: B60R 22/16 using belts which become permanently deformed, i.e. one time use
• CPC Class Codes: B60R 22/18 Anchoring devices
• CPC Class Codes: B60R 22/1952 Transmission of tensioning power by cable; Return motion locking means therefor
• CPC Class Codes: B60R 22/48 Control systems, alarms, or interlock systems, for the correct application of the belt or harness
• 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
• CPC Class Codes: Y10T 24/45623 and operator therefor

Abstract

A force sensor (50, 50′, 50a) generates a signal indicating the usage of a seat belt. A cylindrical housing (70, 70′) has a wall (72) and a bottom (74) which define an internal cavity (88). The bottom has an opening (76) through it. A cable anchor (90) is slidably received within the cavity and is connected to a cable (54). The cable has one end secured to the cable anchor and another end connected to an anchor point. A magnet (120) is connected to a top of the cable anchor and is movable with the cable anchor. The cable anchor is biased to resist motion of the cable anchor toward the bottom of the housing. A magnetic sensor (200) generates a signal indicative of the distance between it and the magnet. A sensor housing (180) is connected to the housing and is positioned on the housing to position the magnetic sensor a determinable distance from the magnet at a null position. A housing end cap (150) is secured to the housing for enclosing an open end of the housing. The magnet and the magnetic sensor are movable when a force of a determinable level is applied to the end cap causing the relative movement of the magnet and the magnetic sensor.

Claims

1. A force sensor for generating a signal indicative of the usage of a seat belt comprising:

a cylindrical first housing (70;

70′

) having a wall (72) and a bottom (74), the bottom including an opening (76), the cylindrical first housing including an internal cavity (124);

a cable anchor (90) slidably received within the cavity and adapted to be connected to a cable (54);

the cable (54) having one end secured to the cable anchor and another end operatively connected to an anchor point;

a magnet (120) operatively connected to a top of the cable anchor and movable with the cable anchor;

first means for biasing the cable anchor to resist motion of the cable anchor toward the bottom of the housing;

a magnetic sensor means (200) for generating a signal indicative of the distance between it and the magnet, such distance proportional to a force applied to the seat belt;

a sensor housing (180) securably connected relative to the cylindrical first housing and positioned upon the first housing to position the sensor means a determinable distance from the magnet at a null position;

a housing end cap (150) securable to the cylindrical first housing for enclosing an open end of the cylindrical first housing, the magnet and the magnetic sensor means being relatively movable when a force of a determinable level is applied to the end cap thereby causing the relative movement of the magnet and the sensor means.

2. The sensor as defined in claim 1 wherein the first means includes a hollow, cylindrical piston (140), within the housing cavity (124) and a spring (148) intermediate the piston and the first housing for biasing the piston and the cable anchor.

3. The sensor as defined in claim 2 further including a low-friction annular guide, cooperable with an exterior wall of the piston to radially stabilize the piston relative to a central axis of the first housing.

4. The sensor as defined in claim 3 wherein the annular guide is formed integrally as a part of the sensor housing.

5. The sensor as defined in claim 1 wherein a top of the cable anchor includes a flange (94) and wherein the cylindrical piston (140) includes a mating wall portion (144a, 144b) to slidably receive the cable anchor and to radially stabilize the cable anchor relative to a central axis of the first housing.

6. The sensor as defined in claim 1 including a magnet retainer (100) for holding the magnet to the cable anchor.

7. The sensor as defined in claim 6 wherein the magnet retainer (100) is non-magnetic.

8. The sensor as defined in claim 7 wherein the magnet retainer is integrally formed as a part of the cable anchor.

9. The force sensor as defined in claim 1 wherein the cable anchor and the first housing include force means for resisting outward deformation of the first housing.

10. The force sensor as defined in claim 1 wherein the sensor housing is secured to one of the end cap and the first housing.