Seat belt tension sensor, methods of integration and attachment

• US 20020145422A1
• Filed: 06/04/2002
• Published: 10/10/2002
• Est. Priority Date: 05/04/2000
• Status: Active Grant

• 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: Grzic, Rudi, OʼNeill, John, Chamings, Antony W.
• Granted Patent: US 6,566,869 B2
• Time in Patent Office: Days
• 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) 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 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 (200) for generating a signal indicative of the distance between it and the magnet;

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

a housing end cap (150) securable to the first housing for enclosing an open end of the first housing, the magnet and the magnetic sensor 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 magnetic sensor.

Claims

1. A force sensor (50;

50′

;

50a) 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 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 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 first housing for enclosing an open end of the first housing, the magnet and the 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 1 wherein a top of the cable anchor includes a flange (94) and wherein the 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.

4. 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.

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

6. The sensor as defined in claim 5 wherein the magnet retainer (100) is non-magnetic.

7. The sensor as defined in claim 6 wherein the magnet retainer (122) is integrally formed as a part of the cable anchor.

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

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.

11. A force sensor (50a) for generating a signal indicative of the usage of a seat belt comprising:

a first housing (70a) having first and a second housing part, the first and second housing parts each including a first bridge portion (400) and a second bridge portion (402), the first bridge portions defining a first passage and the second bridge portions defining a second passage;

a cable anchor (90) slidably received within the first and second passages formed by the bridge portions, the cable anchor adapted to be connected to a cable (54), the cable anchor, at a first anchor end, includes an annular portion 44;

the cable (54) having a first cable end operatively secured to a second anchor end and a second cable end operatively connected to an anchor point;

a magnet (120) operatively connected to annular portion 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 an end of the first housing opposite the location of the magnet;

a sensor housing (180) fixedly positioned between the second bridge portions and located within the second passage, the annular portion of the cable anchor surrounding the sensor housing;

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

the magnet and the magnetic sensor 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.

12. The sensor as defined in claim 11 wherein at least one housing part includes a stop for interacting with a part of the of the annular portion of the cable anchor to prevent excess motion of the cable anchor.

13. The sensor as defined in claim 11 wherein the magnet is supported by a magnet retainer or housing and wherein the magnetic retainer is snapped onto the annular portion of the cable retainer.

14. The sensor as defined in claim 11 wherein the sensor housing includes a low friction surface that extends about opposite sides of the annular portion of the cable anchor to reduce friction between the cable anchor and the housing parts.

15. The sensor as defined in claim 13 wherein the magnet retainer is located on a remote end of the annular portion of the cable anchor and includes wings extending outwardly from opposite sides of the annular portion to provide a low friction surface between the cable anchor and the housing parts.