Inflator second stage combustion control

• US 20080211215A1
• Filed: 05/13/2008
• Published: 09/04/2008
• Est. Priority Date: 11/28/2005
• Status: Active Grant

• Current Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Original Assignee: Autoliv ASP Incorporated (Autoliv Incorporated)
• Inventors: Smith, Bradley W., Rasmussen, Kirk, Hoffman, Isaac
• Granted Patent: US 7,726,687 B2
• Time in Patent Office: Days
• US Class Current: 280/736
• CPC Class Codes: B60R 2021/2633 with a plurality of inflation levels
• CPC Class Codes: B60R 2021/2648 comprising a plurality of combustion chambers or sub-chambers
• CPC Class Codes: B60R 21/2644 using only solid reacting substances, e.g. pellets, powder

Abstract

A new type of airbag inflator that may be used in an airbag system is disclosed. The inflator will generally include a housing and two initiators. Accordingly, the inflator is a “dual-stage” inflator. The two stages are disposed within the housing. The second initiator is disposed within a second stage generant cup. A cap is also used to engage the second stage cup. The cap maintains seated engagement with the second stage cup, even during deployment of the second stage. The second stage will also include one or more perforations, which constitute openings through which gas may flow. When the second initiator is in the unactuated state, these perforations will be isolated from the generant by the cap. Actuation of the second initiator unseals the one or more perforations but does not unseat the cap from the cup, due to constraints put in place to prevent such unseating.

Claims

1. An inflator for inflating an airbag comprising:

a housing;

a first chamber disposed within the housing;

a generant cup and a cap disposed within the housing, the generant cup and the cap defining a second chamber that houses gas generant, the cap engaging the generant cup in seated engagement; and

one or more perforations located on the generant cup, wherein actuation of gas generant in the second chamber unseals the one or more perforations without unseating the cap from the generant cup.

2. An inflator as in claim 1 wherein during actuation of the gas generant in the second chamber, the cap is restrained from unseating from the generant cup by having the cap abut against an upper wall of the housing.

3. An inflator as in claim 1 wherein actuation of the gas generant comprises combustion of the gas generant.

4. An inflator as in claim 1 wherein the pressure of the second chamber during actuation of the gas generant is maintained at a pressure that is greater than atmospheric pressure.

5. An inflator as in claim 1, wherein the first chamber comprises a inflation source, wherein actuation of the first initiator comprises ignition of the inflation source.

6. An inflator as in claim 1, wherein the inflator communicates with a sensor that determines the severity of an impact, wherein if the sensor detects that the severity of the impact is above a first threshold, the inflator actuates gas generant stored in the first chamber.

7. An inflator as in claim 6, wherein if the sensor detects that the severity of the impact is above a second threshold level greater than the first threshold level, the inflator actuates gas generant in both the first chamber and the second chamber.

8. An inflator as in claim 7, wherein if the sensor detects that the severity of the impact is above a second threshold level, the first chamber will be actuated prior to the actuation of the second chamber.

9. An airbag system comprising:

an airbag;

an inflator comprising;

a housing;

a first chamber disposed within the housing;

a generant cup and a cap disposed within the housing, the generant cup and the cap defining a second chamber that houses gas generant, the cap engaging the generant cup in seated engagement;

one or more perforations located on the generant cup, wherein actuation of gas generant in the second chamber unseals the one or more perforations without unseating the cap from the generant cup; and

a sensor that detects the severity of an impact such that if the sensor detects that the severity of the impact is above a first threshold, the inflator actuates gas generant in the first chamber.

10. An airbag system as in claim 9, wherein if the sensor detects that the severity of the impact is above a second threshold level greater than the first threshold level, the inflator actuates gas generant in both the first chamber and the second chamber.

11. An airbag system as in claim 9, wherein the pressure of the second chamber during actuation of the gas generant is maintained at a pressure that is greater than atmospheric pressure.

12. An airbag system as in claim 9 wherein the perforations are also located on the cap, wherein, because of the position of the relative positions of both the cup and the cap, the perforations on both the cap and the cup are sealed by the cap when the inflator is undeployed.

13. An inflator for inflating an airbag comprising:

a housing;

a first chamber disposed within the housing;

a generant cup and a cap disposed within the housing, the generant cup and the cap defining a second chamber that houses gas generant, the cap engaging the generant cup in seated engagement; and

one or more perforations located on the generant cup and on the cap, wherein because of the position of the relative positions of both the cup and the cap, the perforations on both the cap and the cup are sealed by the cap when the inflator is undeployed, wherein actuation of gas generant in the second chamber unseals the one or more perforations without unseating the cap from the generant cup.

14. An inflator as in claim 13 wherein the pressure of the second chamber during actuation of the gas generant is maintained at a pressure that is greater than atmospheric pressure.

15. An inflator as in claim 13, wherein the first chamber comprises a inflation source, wherein actuation of the first initiator comprises ignition of the inflation source.