Weight sensor assembly for determining seat occupant weight

• US 6,494,482 B2
• Filed: 10/05/2001
• Issued: 12/17/2002
• Est. Priority Date: 06/25/1999
• Status: Expired due to Fees

• Current Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Original Assignee: Siemens VDO Automotive Corporation (Siemens AG)
• Inventors: Curtis, Brian M.
• Primary Examiner(s): Dickson, Paul N.
• Assistant Examiner(s): Dunn, David R.
• Application Number:
  US09/971,412
• Publication Number:
  US 20020020994A1
• Time in Patent Office: 438 Days
• Field of Search: 280/735, 180/273, 297/217.2, 738/12, 738/49, 738/53, 738/56, 738/55, 738/624.74, 738/626.27, 738/626.34, 738/626.29, 177/136, 177/211, 177/144
• US Class Current: 280/735
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/0152 using strain gauges
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

A system for measuring the weight of a seat occupant is used to control airbag deployment. The system includes a plurality of weight sensors that have a first end mounted to a seat riser and a second end mounted to a seat frame or track member. The weight sensors have a central bendable portion that extends between the first and second ends. A groove is formed in one of the external surfaces of the central bendable portion to localize strain. A full bridge strain gage assembly is mounted on a surface of each of the weight sensors, opposite from the groove, for generating a weight signal in response to measuring deflection of the central bendable portion. A central processor determines seat occupant weight based on the weight signals and an airbag control module communicates with the processor. The control module controls deployment force of the airbag based on seat occupant weight.

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 sensor assembly mounted between said seat element and said seat support member and having a bendable central body portion for supporting at least one strain gage for measuring strain resulting from a weight force applied to said seat bottom, said bendable central body portion having a partially removed section to concentrate strain in said bendable central body portion wherein said partially removed section comprises a pair of co-linear slots extending through said central body portion and spaced apart from each other across the width of said central body portion by a mount surface.

2. A system according to claim 1 wherein said strain gage is mounted on said mount surface between said slots.

3. A system according to claim 2 wherein said sensor assembly includes a first end for attachment to said seat element and a second end for attachment to said seat support member, said bendable central body portion extending between said first and second ends, and wherein said slots are formed within said central body portion approximately at an equal distance from said first and second ends.

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

a first end rigidly mounted to an upper seat structure;

a second end rigidly mounted to a lower seat structure;

a deflectable central body portion extending between said first and second ends and having an upper surface and a lower surface, said central body portion including a partially removed section for concentrating strain at said central body portion resulting from a weight applied to said upper scat structure wherein said partially removed section comprises a pair of co-linear slots extending through said central body portion and spaced apart from each other across the width of said central body portion by a mount surface; and

a strain gage assembly mounted on said central body portion for measuring the strain at said central body portion.

5. An assembly according to claim 4 wherein said strain gage assembly is mounted on said mount surface between said slots.

6. An assembly according to claim 5 wherein said strain gage assembly and said slots are both located at the middle of said central body portion, approximately equal distances from said first and second ends.

7. A System for measuring a weight on a vehicle seat comprising:

a seat assembly having a seat bottom;

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

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

a plurality of weight sensor assemblies each including a first end rigidly mounted to said scat support member, a second end rigidly mounted to said seat element, a deflectable central body portion extending between said first and second ends and having an upper surface and a lower surface, said central body portion including a partially removed section for concentrating strain at said central body portion resulting from a weight applied to said scat support member wherein said partially removed section comprises a pair of co-linear slots extending through said central body portion and spaced apart from each other across the width of said central body portion, and a strain gage assembly mounted on said central body portion between said slots for measuring the strain at said central body portion wherein each of said weight sensor assemblies generates a weight signal in response to measuring deflection of said central body portion;

a processing unit for receiving said weight signals to quantify the weight applied to said seat assembly; and

at least one safety device control module in communication with said processing unit wherein deployment of at least one safety device is controlled by said safety device control module based on the weight applied to said seat assembly.

8. A system according to claim 7 wherein said slots and said strain gage assembly are both located at the middle of said central body portion, approximately equal distances from said first and second ends.