| 摘要 |
In a retainer 19 which supports an inflator 20 and an air bag 21 of an air bag device Rd, disposed are a control valve 30 configured by bonding a plate-like piezoelectric element 31 to a protector 21 made of a metal, vent holes 29 which are opened and closed by the control valve 30, and internal-pressure detecting means 35d for detecting the internal pressure of the air bag 21. The piezoelectric element 31, which, when not energized, closes the vent holes 29, is caused to bend by energization, so as to open the vent holes 29, thereby allowing a gas in the air bag 21 to be discharged to the outside. The opening degree of the vent holes 29 is feedback controlled in accordance with the air bag internal pressure detected by the internal-pressure detecting means 35d, so that the change of the air bag internal pressure with respect to the elapse of time coincides with a preset internal-pressure pattern. Accordingly, the internal pressure of an air bag is correctly controlled by changing the amount of a gas which is discharged through a vent hole when the air bag develops.
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