Deployment Timing Test of Side-Impact Airbag

Application

While a conventional SRS (Secondary Restraint System) air bag system protects the driver by cushioning the secondary impact with the steering wheel during a frontal impact, the side-impact air bag is designed to gently force an occupant into the center of the vehicle and prevent contact with the door panel.  Side-impact air bags are therefore designed to operate at higher inflation pressures and deflate slower than frontal-impact air bags. The critical test is the timing from the point of triggering the igniter to the point where the air bag begins to fill with gas.  Ideally this time period should be less than 4 ms.  This deployment test procedure should also be recorded by a high speed video camera according to SAE J211.  The video can then be used to investigate, evaluate and analyze problems with the inflator or the structures of the seat or roof rails.

Solution Features

The Yokogawa ScopeCorders provide the following advantages for this application :

1. High Channel Count and Modular Architecture

In addition to measuring the ignition signal and the airbag pressure, other sensors may be valuable such as accelerometers, temperatures, and strain.ScopeCorder Input modules are available providing signal conditioning and scaling for these sensors as well as high sampling rate voltage input modules.

2. Versatile Measurement Functions and Cursors

Time measurements are rapidly achieved using cursor measurements.Other built-in measurements such as rise time can be calculated and saved to storage or captured in a screen shot.

The above figure is an example of measuring the output of a pressure sensor in an airbag.
The trigger point is the firing pulse to the igniter. Delay time from ignition to pressure increase is measured using cursors. ScopeCorders can display all acquired data even when using high speed sampling within a long time window.