Seat belt force sensor system

Abstract

A system for measuring seat belt forces is used to control deployment of vehicle airbags. The system includes a rigid plate member having one end attached to a portion of the seat belt and an opposite end mounted to a vehicle structure. The seat belt is used to secure passengers or an infant car seat to the vehicle seat. A sensor including a strain gage is mounted on the rigid plate between the ends and is used to measure the magnitude of forces exerted on the seat belt by the passenger or car seat. The strain gage generates a signal representative of the tension in the seat belt, which is used to control deployment of the airbag. The airbag is not deployed if the tension in the seat belt exceeds a predetermined limit.

1 . A sensor system for controlling airbag deployment comprising: 
 a rigid plate having a first end adapted to support a portion of a seat belt and a second end adapted for attachment to a vehicle structure;    a strain gage mounted on said rigid plate between said first and second ends for measuring the strain exerted on said rigid plate by a tension force applied to the seat belt; and    an electrical connector mounted to said rigid plate adjacent to said strain gage for receiving strain measurements from said strain gage and transmitting said measurements to a processor to determine the magnitude of the tension force wherein the processor generates a force signal representative of the magnitude of said tension force and wherein airbag deployment is controlled based on said force signal.    
   
   
       2 . The sensor system according to  claim 1  including an airbag adapted for mounting adjacent to a vehicle seat.  
   
   
       3 . The sensor system according to  claim 2  wherein said airbag does not deploy when said force signal exceeds a predetermined limit.  
   
   
       4 . The sensor system according to  claim 1  wherein said rigid plate includes a neck portion positioned between said first and second ends, said neck portion having a width that is less than a width of said first and second ends and wherein said strain gage is mounted on said neck portion.  
   
   
       5 . The sensor system according to  claim 1  including a printed circuit board supported by said electrical connector.  
   
   
       6 . The sensor system according to  claim 1  including an electronic control unit incorporated into said electrical connector.  
   
   
       7 . The sensor system according to  claim 1  wherein attachment of said second end to the vehicle structure comprises a rigid attachment.  
   
   
       8 . The sensor system according to  claim 7  wherein said second end of said rigid plate is directly securable to a rigid structure with at least one fastening element.  
   
   
       9 . The sensor system according to  claim 8  wherein said at least one fastening element comprises a pin.  
   
   
       10 . The sensor system according to  claim 8  wherein said at least one fastening element comprises a mechanical fastener.  
   
   
       11 . The sensor system according to  claim 1  wherein the portion of the seat belt is solely supported by said first end.  
   
   
       12 . A method for controlling airbag deployment comprising the steps of: 
 (a) providing a sensor assembly including a rigid plate having a first end adapted to support a seatbelt portion and a second end adapted for securement to a vehicle structure;    (b) mounting a strain gage to the rigid plate between the first and second ends;    (c) mounting an electrical connector to the rigid plate adjacent to the strain gage;    (d) measuring strain on the rigid plate due to seatbelt tension force with the strain gage; and    (e) controlling airbag deployment based on strain measured in step (d).    
   
   
       13 . The method according to  claim 12  including the step of mounting a printed circuit board to the electrical connector.  
   
   
       14 . The method according to  claim 12  including forming the rigid plate as a single rigid plate and wherein step (b) includes mounting the strain gage directly to the single rigid plate.  
   
   
       15 . The method according to  claim 12  including solely supporting the seatbelt portion with the first end.  
   
   
       16 . The method according to  claim 12  including fastening the second end directly to a rigid structure with at least one fastening element.  
   
   
       17 . The method according to  claim 12  including not deploying an airbag when the strain exceeds a predetermined limit.  
   
   
       18 . The method according to  claim 12  including forming the rigid plate as a single rigid plate and wherein step (b) includes mounting the strain gage directly to the single rigid plate.  
   
   
       19 . The method according to  claim 12  including solely supporting the seatbelt portion with the first end.  
   
   
       20 . The method according to  claim 12  including fastening the second end directly to a rigid structure with at least one fastening element.