Vehicle occupant weight estimation apparatus having fluid-filled seat bladder

Apparatus for estimating the weight of an occupant of a seat in a motor vehicle, the seat having a foam cushion bottom, the apparatus comprising:

• a closed elastomeric bladder disposed in the foam cushion bottom, the bladder being substantially filled with fluid, and having a exit port;
• a pressure sensor coupled to said exit port for sealing said exit port and for sensing the pressure of said fluid;
• a temperature sensor for sensing a temperature in proximity to said bladder;
• and
• control means for estimating the weight of the occupant based on the sensed fluid pressure and the sensed temperature, and providing a status signal to an air bag deployment system, said control means including:
• means for sampling an output of said pressure sensor, compensating said sampled output for temperature based on an output of said temperature sensor, and comparing said compensated pressure sensor output to a threshold signal corresponding to a threshold occupant weight;
• and
• means for setting said status signal to a value for inhibiting air bag deployment when said comparison indicates that the estimated occupant weight is less than said threshold weight, and for setting said status signal to a value for allowing air bag deployment when said comparison indicates that the estimated occupant weight is greater than said threshold weight.