Propellant cage and packing element for a tubular inflator

1. A packing element ( 50 ) for a tubular inflator ( 100 ) for fixing a propellant bed located in a propellant chamber ( 14 ) of the tubular inflator ( 100 ), wherein the packing element ( 50 ) is formed at a propellant bed-side end ( 52 ) so as to receive and partially enclose and/or support a propellant cage ( 10 );

wherein the the propellant cage ( 10 ) forms a propellant chamber ( 14 ) and a flow passage ( 15 ) of the tubular inflator ( 100 ), wherein the propellant cage ( 10 ) is in the form of a propellant cage spiral spring ( 11 ) having a gas inlet-side end ( 12 ) and a gas outlet-side end ( 13 ), wherein the gas inlet-side end ( 12 ) has a smaller cross-section than the gas outlet-side end ( 13 );

wherein a configuration of the packing element is a packing spiral spring ( 51 ) which includes plural portions in an axial direction having different diameters and/or clearances of spring windings; and

wherein the packing spiral spring ( 51 ) includes a first igniter carrier-side portion ( 53 ), a second central portion ( 54 ) and a frontal end portion ( 55 ), the central portion being tapered ( 54 ) and being widened in the direction of the frontal end portion ( 55 ) and having a smaller spring winding clearance as compared to the igniter carrier-side portion ( 53 ).

2. The packing element ( 50 ) according to claim 1 , wherein a clearance of spring windings ( 17 ) in the area of the gas outlet-side end ( 13 ) is smaller than at least one of a clearance of spring windings ( 18 ) in the area of the gas inlet-side end ( 12 ) and a clearance of spring windings ( 19 ) of a central spring portion ( 40 ) of the propellant cage ( 10 ), wherein the propellant cage ( 10 ) at least in portions has a funnel-shaped ( 42 ) or trumpet-shaped design.

3. The packing element ( 50 ) according to claim 1 , wherein the spring winding clearance in the frontal end portion ( 55 ) is larger than the spring winding clearance in the central portion ( 54 ) of the packing spiral spring ( 51 ) and is smaller than the spring winding clearance of the first igniter carrier-side portion ( 53 ).

4. The packing element ( 50 ) according to claim 1 , further comprising a radial ring element ( 60 ) at which an axially extending sleeve ( 61 ) is formed, wherein the sleeve ( 61 ) has at least one radially inwardly extending tab ( 62 ).

5. A tubular inflator ( 100 ) for an airbag module, comprising a tubular housing ( 31 ) and a propellant cage ( 10 , 11 ) forming a propellant chamber ( 14 ) and a flow passage ( 15 ) of the tubular inflator ( 100 ), wherein the propellant cage ( 10 ) is in the form of a propellant cage spiral spring ( 11 ) having a gas inlet-side end ( 12 ) and a gas outlet-side end ( 13 ), wherein the gas inlet-side end ( 12 ) has a smaller cross-section than the gas outlet-side end ( 13 ), wherein the propellant cage ( 10 , 11 ) is arranged inside the tubular housing ( 31 ) and the tubular housing ( 31 ) delimits, at least in portions, the propellant chamber ( 14 ) and forms the flow passage ( 15 ), wherein the tubular inflator further comprises a packing element ( 50 ) according to claim 1 .

6. The tubular inflator ( 100 ) according to claim 5 , wherein the gas outlet-side end ( 13 ) of the propellant cage ( 10 , 11 ) rests on a bead ( 32 ) of the tubular housing ( 31 ) of the tubular inflator ( 100 ), wherein the bead ( 31 ) is formed in at least one of an igniter-side front third, an igniter-side front quarter, and an igniter-side front fifth, of the tubular housing ( 31 ).

7. The tubular inflator ( 100 ) according to claim 5 , wherein the gas inlet-side end ( 12 ) of the propellant cage ( 10 , 11 ) and the propellant bed-side end ( 52 ) of the packing element ( 50 , 51 ) are formed substantially in a joint plane.

8. The tubular inflator ( 100 ) according to claim 5 , wherein the propellant cage ( 10 ) and the packing element ( 50 ) are positioned to be overlapping each other at least in portions in the axial direction.

9. The tubular inflator ( 100 ) according to claim 5 , wherein the packing element ( 50 , 51 ) is at least one of screwed, fitted, and clipped onto the propellant cage ( 10 , 11 ).

10. The tubular inflator ( 100 ) according to claim 5 , wherein the clearances of the spring windings of the propellant cage spiral spring ( 11 ) are configured relative to propellant bodies ( 16 ) of the propellant bed in such way that the propellant bodies ( 16 ) cannot enter into the flow passage ( 15 ) and/or in that the tubular inflator ( 100 ) is operable according to a shock wave principle.

11. An airbag module comprising a tubular inflator ( 100 ), an airbag inflatable by the tubular inflator ( 100 ) and a securing unit for attaching the airbag module to a vehicle, wherein the tubular inflator ( 100 ) is configured according to claim 5 .

12. A vehicle safety system comprising a tubular inflator ( 100 ), an airbag inflatable by the tubular inflator ( 100 ) as part of an airbag module, and an electronic control unit by means of which the tubular inflator ( 100 ) can be activated when a trigger situation is given, wherein the tubular inflator ( 100 ) is configured according to claim 5 .

13. A method of operating the tubular inflator ( 100 ) according to claim 5 , comprising the following steps of:

triggering an igniter unit ( 20 ) for generating ignition gas inside an ignition chamber ( 23 );

axially introducing the ignition gas into the flow passage ( 15 ) encompassed by the propellant cage ( 10 , 11 );

discharging part of the ignition gas via at least one lateral gas flow opening ( 41 ) of the propellant cage ( 10 , 11 ) into the propellant chamber ( 14 ) radially inwardly delimited by the propellant cage ( 10 , 11 );

igniting propellant bodies ( 16 ) within the propellant chamber ( 14 ) by the ignition gas, wherein propellant gas is generated; and

passing the propellant gas out of the propellant chamber ( 14 ) into a gas chamber ( 70 ).

14. The method according to claim 13 , wherein during the step of axially introducing the ignition gas, a shock wave front is initiated which flows in the direction of a longitudinal axis directly through the gas chamber ( 70 ) and opens a bursting element ( 35 ) formed at a longitudinally axial end of the gas chamber ( 70 ).

15. A method of manufacturing a tubular inflator ( 100 ) according to claim 5 , comprising the following steps of:

inserting the propellant cage ( 10 , 11 ) into the tubular housing ( 31 ) of the tubular inflator in such way that the gas outlet-side end ( 13 ) of the propellant cage ( 10 , 11 ) rests on a bearing element;

filling propellant bodies ( 16 ) into a space ( 14 ) formed by the propellant cage ( 10 , 11 ) and the tubular housing ( 31 ) and forming the propellant bed;

placing the packing element ( 50 , 51 ) onto the propellant bed and axially biasing the propellant bed, wherein the packing element ( 50 , 51 ) is designed as part of an assembly unit and is placed, together with the assembly unit, onto the propellant bed.

16. The method according to claim 15 , further comprising the step of filling a gas chamber ( 70 ) with a gas or a gas mixture.

17. The method according to claim 15 , wherein the step of placing the packing element ( 50 , 51 ) onto the propellant bed and axially biasing the propellant bed comprises at least one of screwing, fitting and clipping the packing element ( 50 , 51 ) onto the propellant cage ( 10 , 11 ).

18. The method according to claim 15 , further comprising the step of elongating the gas inlet-side end ( 12 ) of the propellant cage ( 11 ) in a direction opposed to the bearing element.

19. The method according to claim 18 , wherein the step of elongating the gas inlet-side end ( 12 ) of the propellant cage ( 11 ) comprises using a tool comprising a stopper device so that during elongation the propellant cage ( 11 ) is held in position relative to the bearing element.

20. A tubular inflator ( 100 ) comprising the packing element ( 50 ) of claim 1 .

21. An airbag module comprising the tubular inflator ( 100 ) of claim claim 20 .

22. A vehicle safety system comprising the airbag module of claim claim 21 .

23. A method of manufacturing a tubular inflator ( 100 ) for an airbag module, comprising a tubular housing ( 31 ) and a propellant cage ( 10 , 11 ) forming a propellant chamber ( 14 ) and a flow passage ( 15 ) of the tubular inflator ( 100 ), wherein the propellant cage ( 10 ) is in the form of a propellant cage spiral spring ( 11 ) having a gas inlet-side end ( 12 ) and a gas outlet-side end ( 13 ), wherein the gas inlet-side end ( 12 ) has a smaller cross-section than the gas outlet-side end ( 13 ), wherein the propellant cage ( 10 , 11 ) is arranged inside the tubular housing ( 31 ) and the tubular housing ( 31 ) delimits, at least in portions, the propellant chamber ( 14 ) and forms the flow passage ( 15 ), wherein the tubular inflator further comprises a packing element ( 50 ) for fixing a propellant bed located in the propellant chamber ( 14 ) of the tubular inflator ( 100 ), wherein the packing element ( 50 ) is formed at a propellant bed-side end ( 52 ) so as to receive and partially enclose and/or support the propellant cage ( 10 ), and wherein the propellant cage ( 10 ) forms the propellant chamber ( 14 ) and the flow passage ( 15 ) of the tubular inflator ( 100 ), wherein the method comprising the following steps of:

inserting the propellant cage ( 10 , 11 ) into the tubular housing ( 31 ) of the tubular inflator in such way that the gas outlet-side end ( 13 ) of the propellant cage ( 10 , 11 ) rests on a bearing element;

filling propellant bodies ( 16 ) into a space ( 14 ) formed by the propellant cage ( 10 , 11 ) and the tubular housing ( 31 ) and forming the propellant bed;

placing the packing element ( 50 , 51 ) onto the propellant bed and axially biasing the propellant bed, wherein the packing element ( 50 , 51 ) is designed as part of an assembly unit and is placed, together with the assembly unit, onto the propellant bed; and

elongating the gas inlet-side end ( 12 ) of the propellant cage ( 11 ) in a direction opposed to the bearing element.

24. The method according to claim 23 , wherein the step of elongating the gas inlet-side end ( 12 ) of the propellant cage ( 11 ) comprises using a tool comprising a stopper device so that during elongation the propellant cage ( 11 ) is held in position relative to the bearing element.