Knee airbag module
A knee airbag module of a vehicle occupant restraint system comprises an outer housing ( 14 ) in which an airbag ( 20 ) folded into an airbag package prior to its deployment as well as an inflator ( 16 ) generating filling gas for filling the airbag ( 20 ) are accommodated. In the outer housing ( 14 ) an exit opening ( 22 ) is formed through which the airbag ( 20 ) leaves the outer housing ( 14 ) during deployment. The airbag ( 20 ) is subdivided into plural chambers ( 28 a - 28 f ) arranged in series and being in fluid communication. The chamber closest to the inflator ( 28 a ) is separated from an adjacent chamber ( 28 b ) by a wall ( 32 ) which in the inflated airbag ( 20 ) extends substantially in the area of the exit opening ( 22 ) along the exit opening ( 22 ).
1. A knee airbag module of a vehicle occupant restraint system, comprising an outer housing ( 14 ; 114 ) in which an airbag ( 20 ; 120 ) folded into an airbag package ( 18 ) prior to its deployment and an inflator ( 16 ; 116 ) for generating filling gas for filling the airbag ( 20 ; 120 ) are accommodated, wherein an exit opening ( 22 ; 122 ) oriented downwards in the mounting position through which during deployment the airbag ( 20 ; 120 ) leaves the outer housing ( 14 ; 114 ) is formed in the outer housing ( 14 ; 114 ), wherein the airbag ( 20 ; 120 ) is subdivided into plural chambers ( 28 a - 28 f ; 128 a - 128 f ) arranged in series and being in flow communication, a chamber closest to the inflator ( 28 a ; 128 a ) being separated from an adjacent chamber ( 28 b ; 128 b ) by a wall ( 32 ; 132 ) which in the inflated airbag ( 20 ; 120 ) substantially extends in the area of the exit opening ( 22 ; 122 ) along the exit opening ( 22 ; 122 ), and wherein upon activation of the inflator ( 28 a ; 128 a ), the chamber closest to the inflator ( 28 a ; 128 a ) deploys in the area of the exit opening ( 22 ; 122 ) so that the remaining portions of the airbag package ( 18 ) are initially positioned vertically downward from the exit opening ( 22 ; 122 ) and deploy vertically upward therefrom toward a vehicle occupant.
2. The knee airbag module according to claim 1 , wherein the chamber closest to the inflator ( 28 a ; 128 a ) is arranged inside the outer housing ( 14 ; 114 ) so that it fills at least partially and generates a force (F) directed out of the outer housing ( 14 ; 114 ) toward the remaining airbag package ( 18 ).
3. The knee airbag module according to claim 1 , wherein the chamber closest to the inflator ( 28 a ; 128 a ) is arranged in the folded airbag package ( 18 ) such that upon activation of the inflator ( 16 ; 116 ) at first the chamber closest to the inflator ( 28 a ; 128 a ) will fill, while the remaining airbag package ( 18 ) still remains substantially in the folded state.
4. The knee airbag module according to claim 1 , wherein the airbag package ( 18 ) is folded and the chamber closest to the inflator ( 28 a ; 128 a ) is arranged in such manner that the filling gas generated by the inflator ( 16 ; 116 ) at first flows directly and completely into the chamber closest to the inflator ( 28 a ; 128 a ).
5. The knee airbag module according to claim 1 , wherein in the inflated state the chamber closest to the inflator ( 28 a ; 128 a ) substantially completely fills the compartment inside the outer housing ( 14 ; 114 ).
6. The knee airbag module according to claim 1 , wherein the wall ( 32 ; 132 ) separating the chamber closest to the inflator ( 28 a ; 128 a ) from the remaining airbag package ( 18 ) in the inflated state of the airbag ( 20 ; 120 ) is located in the plane or substantially in parallel to the plane of the exit opening ( 22 ; 122 ).
7. The knee airbag module according to claim 1 , wherein the wall ( 32 ) is formed by a constriction ( 34 ) or a partition between the chamber closest to the inflator ( 28 a ) and an adjacent second chamber ( 28 b ) which is connected to at least one flow orifice.
8. The knee airbag module according to claim 1 , wherein the wall ( 132 ) is formed by at least one tether extending inside the airbag ( 120 ) which connects two opposite outer wall portions ( 150 , 152 ) of the airbag ( 120 ) and limits a maximum distance between the outer wall portions ( 150 , 152 ).
9. The knee airbag module according to claim 1 , wherein the airbag ( 20 ; 120 ) includes at least three chambers arranged in series ( 28 a - 28 f ; 128 a - 128 f ), wherein the chamber closest to the inflator ( 28 a ; 128 a ) abuts on a second chamber ( 28 b ; 128 b ) and the second chamber ( 28 b ; 128 b ) abuts on a third chamber ( 28 c ; 128 c ) so that the airbag ( 20 ; 120 ) in total takes a curved shape in the inflated state.
10. The knee airbag module according to claim 9 , wherein the chamber closest to the inflator ( 28 a ; 128 a ), the second chamber ( 28 b ; 128 b ) and the third chamber ( 28 c ; 128 c ) describe approximately an angle of 90°, with the second chamber ( 28 b ; 128 b ) being aligned with the interior of the outer housing ( 14 ; 114 ).
11. The knee airbag module according to claim 9 , wherein the second chamber ( 28 b ; 128 b ) is separated from the third chamber ( 28 c ; 128 c ) by a partition ( 40 ; 140 ) which is provided with at least one flow orifice and, in the inflated state of the airbag ( 20 ; 120 ), extends at an angle of 0 to 30° with the vertical.
12. The knee airbag module according to claim 1 , wherein the chamber closest to the inflator ( 28 a ; 128 a ) in the inflated state of the airbag ( 20 ; 120 ) has a smaller volume than the adjacent second chamber ( 28 b ; 128 b ).
13. A knee airbag module of a vehicle occupant restraint system, comprising an outer housing ( 14 ; 114 ) in which an airbag ( 20 ; 120 ) folded into an airbag package ( 18 ) prior to its deployment and an inflator ( 16 ; 116 ) for generating filling gas for filling the airbag ( 20 ; 120 ) are accommodated, wherein an exit opening ( 22 ; 122 ) oriented downwards in the mounting position through which during deployment the airbag ( 20 ; 120 ) leaves the outer housing ( 14 ; 114 ) is formed in the outer housing ( 14 ; 114 ), wherein the airbag ( 20 ; 120 ) is subdivided into at least three chambers ( 28 a - 28 f ; 128 a - 128 f ) arranged in series and being in flow communication, a chamber closest to the inflator ( 28 a ; 128 a ) abutting on a second chamber ( 28 b ; 128 b ) and being separated from the second chamber ( 28 b ; 128 b ) by a wall ( 32 ; 132 ), the wall ( 32 ; 132 ) substantially extending in the area of the exit opening ( 22 ; 122 ) along the exit opening ( 22 ; 122 ) when the airbag ( 20 ; 120 ) is in the inflated state, and wherein the second chamber ( 28 b ; 128 b ) abuts on a third chamber ( 28 c ; 128 c ) and is separated from the third chamber ( 28 c ; 128 c ) by a partition ( 40 ; 140 ), the partition ( 40 ; 140 ) having at least one flow orifice, the partition ( 40 ; 140 ) extending at an angle of 0 to 30° relative to the vertical when the airbag ( 20 ; 120 ) is in the inflated state.