Understanding car seat components

Upholstery Journal | April 2008

Airbags are tightly folded into their casings. Many types rapidly expand upon deployment when filled with compressed gas from a cylinder that is activated by SRS sensors.

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Tackle airbag & electronics-related upholstery challenges

Remember the good old days when a seat was just a seat? The seats in today’s automobiles are stocked with all manner of gadgetry.

“It’s not simple, like it used to be,” says Jeff Poole of I-Car. “Every facet of the upholstery industry is getting exponentially more complicated.” Some of the seat electronics that affect upholsterers the most are seat position sensors, occupant classification systems and anti-whiplash systems. Seat position sensors take input information about an occupant’s position in the seat. A computer determines whether or not to deploy an airbag, or decides which airbags to deploy, in the event of a crash, based upon whether or not the occupant is in the airbag deployment zone. Position sensors are installed in the seat track.

Occupant Classification Systems (OCS) are designed to detect the presence of an occupant in the passenger seat. A seat-occupied sensor deploys the airbag in the event of a crash based on the input it receives. If the seat is occupied, the airbag will deploy. Information about the occupant’s weight is determined by a pressure bladder or strain gauges located in the seat.

“Basically, an OCS measures the weight of the occupant and determines whether or not the airbag should go off,” says Ryan Summerill of AAA Top Shop. “If those complex calibrations are off, they can default. You have to work very, very carefully with them. Some of them need to be recalibrated every time.”

Poole elaborates by describing the pressure sensors in some seats. “Many OCS systems use a liquid-filled-plastic balloon that activates a pressure sensor module. The ones that are really hitting us in collision repair industry are the strain gauge systems,” Poole says. “There can be up to four sensors—one in each corner of the seat. If the vehicle has been in a collision, those need to be recalibrated. If you’ve loosened or taken the seat out, they have to be recalibrated. They’re particular.”

Anti-whiplash systems involve energy-absorbing seats that are devised to minimize whiplash injuries during rear-end collisions. The seats change position with the occupant’s movement.

While providing the customer with a satisfactory finished product is the main goal, safety is always essential. When removing a seat, make sure it is grounded to eliminate the chance of static electricity deploying an airbag. Hold the seat away from your body and keep your hands clear of the airbag areas.

Airbags are tightly folded into their casings. Many types rapidly expand upon deployment when filled with compressed gas from a cylinder that is activated by SRS sensors.
Even light charges generated by static electricity can deploy an airbag. Make sure to carry airbags so they deploy away from your body, and store the undeployed airbag in a safe place away from stray voltage and static electricity.
Seat mounted side airbags protect passengers from side impact crashes. Most seats have a yellow-colored connector that links the seat airbags to their power supply.
The VIN and owner’s manual of a vehicle can help you identify the location and types of airbags that are installed in a specific automobile. Make sure that the 12-volt electrical system and airbag fuse are removed before working with airbag components.

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