Sensor assembly for measuring weight applied to a vehicle seat

• US 6,882,281 B2
• Filed: 11/08/2001
• Issued: 04/19/2005
• Est. Priority Date: 11/28/2000
• Status: Expired due to Fees

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Baker, Michael, Curtis, Brian M.
• Primary Examiner(s): Lieu, Julie B.
• Application Number:
  US10/010,471
• Publication Number:
  US 20020063630A1
• Time in Patent Office: 1,258 Days
• Field of Search: 340/665, 340/666, 340/667, 340/668, 180/271, 180/273, 280/735
• US Class Current: 340/667
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/0152 using strain gauges

Abstract

Weight sensor assemblies for measuring weight on a vehicle seat are mounted at the connecting points between a seat bottom frame and a seat mounting member. The weight sensor assemblies each include a beam member having a bendable center body portion for supporting a stain gage. The strain gage and associated traces are screen printed on the surface of the beam. The beam acts similar to a dual constrained cantilever beam, concentrating the bending at a reduced neck section that narrows in the middle of the center body portion. The strain gage measures strain resulting from bending in the center body portion caused by a weight force being applied against the seat.

Claims

1. A system for measuring a weight on a vehicle seat comprising:

a seat having a seat bottom;

a seat element for mounting said seat to a vehicle structure;

a seat support member for supporting said seat bottom relative to said seat element;

a bending beam with a first connecting portion for connection to said seat support member, a second connecting portion for connection to said seat element, and a central body portion extending between said first and second connecting portions, said central body portion having a narrowing neck section to concentrate strain in said central body portion; and

at least one sensor mounted directly to said narrowing neck section for measuring strain resulting from a weight force applied to said seat bottom wherein said beam includes an extension portion extending beyond one of said first or second connecting portions for supporting an electrical connector for connecting said sensor to a processing unit.

2. A system according to claim 1 wherein said bending beam defines a first width at said first and second connecting portions and said neck section defines a second width that is narrower than said first width.

3. A system according to claim 2 wherein said first connecting portion provides sole connection of said bonding beam to said seat support member and said second connecting portion provides sole connection of said bending beam to said seat element.

4. A system according to claim 2 wherein said first and second connecting portions and said central body portion are coplanar.

5. A system according to claim 4 wherein said first and second connecting portions and said central body portion form an hourglass shape.

6. A system according to claim 1 wherein said beam defines a longitudinal axis and said extension portion includes a mount for receiving said electrical connector via a linear insertion force along said longitudinal axis.

7. A system according to claim 6 wherein said electrical connector includes a first connector portion directly attached to one end of said beam and a second connector portion selectively mateable to said first connector portion to complete electrical connection between said sensor and said processing unit.

9. A system according to claim 1 wherein said first connecting portion includes a first aperture for receiving a first fastener and said second connecting portion includes a second aperture for receiving a second fastener.

8. A system for measuring a weight on a vehicle seat comprising:

a seat having a seat bottom;

a seat element for mounting said seat to a vehicle structure;

a seat support member for supporting said seat bottom relative to said seat element;

a bending beam with a first connecting portion for connection to said seat support member, a second connecting portion for connection to said seat element, and a central body portion extending between said first and second connecting portions, said central body portion having a narrowing neck section to concentrate strain in said central body portion;

at least one sensor mounted directly to said narrowing neck section for measuring strain resulting from a weight force applied to said seat bottom; and

traces for electrically connecting said sensor to an electronics package wherein said sensor and said traces are screen printed on said beam.

10. A system for measuring a weight on a vehicle seat comprising:

a seat having a seat bottom;

a seat element for mounting said seat to a vehicle structure;

a seat support member for supporting said seat bottom relative to said seat element;

a bending beam with a first connecting portion for connection to said seat support member, a second connecting portion for connection to said seat element, and a central body portion extending between said first and second connecting portions, said central body portion having a narrowing neck section to concentrate strain in said central body portion wherein said first connecting portion includes a first aperture for receiving a first fastener and said second connecting portion includes a second aperture for receiving a second fastener;

at least one sensor mounted directly to said narrowing neck section for measuring strain resulting from a weight force applied to said seat bottom; and

a first insert mounted within said first aperture and having a first internal central bore for receiving said first fastener and a first stepped portion formed about an external perimeter of said first insert wherein said first stepped portion has a greater diameter than said first aperture such that a first gap is formed between said seat support member and said beam and including a second insert mounted within said second aperture and having a second internal central bore for receiving said second fastener and a second stepped portion formed about an external perimeter of said second insert wherein said second stepped portion has a greater diameter than said second aperture such that a second gap is formed between said seat element and said beam.

11. A system for measuring a weight on a vehicle seat comprising:

a seat having a seat bottom;

a seat element for mounting said seat to a vehicle structure;

a seat support member for supporting said seat bottom relative to said seat element;

a bending beam with a first connecting portion for connection to said seat support member, a second connecting portion for connection to said seat element, and a central body portion extending between said first and second connecting portions, said central body portion having a narrowing neck section to concentrate strain in said central body portion wherein said first connecting portion includes a first aperture for receiving a first fastener and said second connecting portion includes a second aperture for receiving a second fastener;

a first shim having a first internal central bore for receiving said first fastener and a first connector for attaching said first shim to said beam and including a second shim having a second internal bore for receiving said second fastener and a second connector for attaching said second shim to said beam; and

at least one sensor mounted directly to said narrowing neck section for measuring strain resulting from a weight force applied to said seat bottom.

12. A system according to claim 11 wherein said first shim is mounted in direct engagement with an upper surface of said first connecting portion and said second shim is mounted in direct engagement with a lower surface of said second connecting portion.

14. A system according to claim 11 wherein said first connector comprises at least one first hole and said first connecting portion includes at least one first corresponding hole spaced outwardly from said first aperture and aligned with said first hole for receiving a first pin and wherein said second connector comprises at least one second hole and said second connecting portion includes at least one second corresponding hole spaced outwardly from said second aperture and aligned with said second hole for receiving a second pin.

13. A system according to claimd 11 wherein said first connector comprises a first transversely extending tab and said first connecting portion includes a first slot spaced outwardly from said first aperture for receiving said first transversely extending tab and wherein said second connector comprises a second transversely extending tab and said second connecting portion includes a second slot spaced outwardly from said second aperture for receiving said second transversely extending tab.

15. A weight sensor assembly for measuring a weight on a vehicle seat comprising:

a bending beam having a first connection portion engogeable with on upper seat structure and a second connection portion engageable with a lower seat structure;

a bendable central body portion coplanar with and extending between said first and second connection portions, said central body portion having a narrowing neck to concentrate strain in said central body portion; and

a strain gage assembly mounted directly to said narrowing neck for measuring the strain at said central body portion resulting from a weight force being exerted against the upper seat structure wherein said beam includes an extension portion extending beyond one of said first or second connection portions for supporting an electrical connector to connect said strain gage to a processing unit.

16. An assembly according to claim 15 wherein said beam defines a longitudinal axis and said extension portion includes a mount for receiving said electrical connector via a linear insertion force along said longitudinal axis.

17. An assembly according to claim 16 wherein said electrical connector includes a first connector portion directly attached to one end of said beam and a second connector portion selectively mateable to said first connector portion to complete electrical connection between said sensor and said processing unit.

18. An assembly according to claim 15 including an electronics package mounted on said beam adjacent to said electrical connector.

19. An assembly according to claim 18 including traces for electrically connecting said strain gage assembly to said electronics package wherein said strain gage assembly, said traces, and said electronic package are screen printed on said beam.

20. An assembly according to claim 19 including a protective member for enclosing said electronics package.

21. A weight sensor assembly for measuring a weight on a vehicle seat comprising:

a bending beam having a first connection portion engageable with an upper seat structure and a second connection portion engageable with a lower seat structure;

a bendable central body portion coplanar with and extending between said first and second connection portions, said central body portion having a narrowing neck to concentrate strain in said central body portion; and

a strain gage assembly mounted directly to said narrowing neck for measuring the strain at said central body portion resulting from a weight force being exerted against the upper seat structure

wherein sold first connecting portion includes a first aperture for receiving a first fastener and said second connecting portion includes a second aperture for receiving a second fastener, said first fastener providing sole connection of said beam to said upper seat structure and said second fastener providing sole connection of said beam to said lower seat structure, including a first insert mounted within said first aperture and having a first internal central bore for receiving said first fastener and a first stepped portion formed about an external perimeter of said first insert wherein said first stepped portion has a greater diameter than said first aperture such that a first gap is formed between said upper seat structure and said beam and including a second insert mounted within said second aperture and having a second internal central bore for receiving said second fastener and a second stepped portion formed about an external perimeter of said second insert wherein said second stepped portion has a greater diameter than said second aperture such that a second gap is formed between said lower seat structure and said beam.

22. An assembly according to claim 21 including a first shim having a first center opening in alignment with said first internal central bore for receiving said first fastener and a second shim having a second center opening in alignment with said second internal bore for receiving said second fastener wherein said first shim is positioned between an upper surface of said first connecting portion and said upper seat structure and said second shim is positioned between a lower surface of said second connecting portion and said lower seat structure.

23. A weight sensor for measuring a weight on a vehicle seat comprising:

a bending beam having a first connection portion engageable with an upper seat structure and a second connection portion engageable with a lower seat structure;

a bendable central body portion extending between said first and second connection portions; and

a sensor assembly comprising a first thick film portion applied directly to said central body portion for measuring the strain resulting from a weight force being exerted against the upper seat structure wherein said sensor assembly generates a weight signal representative of said weight force,

wherein said traces include a second thick film portion formed contiguously with said first thick film portion

wherein said first and second thick film portions are screen printed on said bending beam using a thick film material,

wherein said sensor assembly comprises a plurality of grids with associated electronics to form a full-bridge strain gage,

including an electrical connector cooperating with said electrical component to communicate said weight signal to said control unit,

wherein said bonding beam defines a longitudinal axis and includes an extension portion formed at one end for supporting said electrical connector wherein said electrical connector is coupled to said electrical component via a linear insertion force in a direction generally parallel to said longitudinal axis.