External airbag systems for pedestrian protection

Abstract

An external airbag system includes an airbag, a bracket, an inflator, and a trim panel. The airbag has an upper chamber and a parallel lower chamber, the upper chamber and the lower chamber being sealingly separated by a transversely extending first seam. The bracket is connected to the airbag at the first seam. The inflator is fixed relative to the bracket and is in fluid communication with the airbag. The trim panel is fixed to the bracket, enclosing the airbag therebetween. The trim panel has a tear seam substantially aligned with the airbag.

Description

Technical Field

[0001] The invention relates to an external airbag system for pedestrian protection. Background Art

[0002] Anticipated regulations and rating systems, such as Global Technical Regulation No. 9 (GTR9) for pedestrian safety and the United States New Car Assessment Program for the year 2020 (USNCAP 2020), include pedestrian protection performance targets. Pedestrian protection targets include equipping vehicles with a pedestrian autonomous emergency braking (PAEB) system that includes a pedestrian detection system and an automatic braking device in response to a pedestrian sensed in the path ahead. The regulations and ratings also evaluate the effectiveness of the protection provided to pedestrians in the event of a vehicle-pedestrian contact. The front end of a truck, such as a pick-up truck, presents many design challenges in improving pedestrian protection. There are still opportunities to provide improved pedestrian protection. Summary of the invention

[0003] According to the present invention, there is provided an external airbag system, comprising:

[0004] an air bag having an upper chamber and a parallel lower chamber, the upper chamber and the lower chamber being sealingly separated by a transversely extending first seam;

[0005] a bracket connected to the air bag at a first seam;

[0006] an inflator fixed relative to the bracket and in fluid communication with the air bag; and

[0007] A trim panel is fixed to the bracket, enclosing the air bag therebetween and having a tear seam substantially aligned with the air bag.

[0008] According to one embodiment of the present invention, the bracket includes an upper chute engaging an upper chamber of the airbag and a lower chute engaging a lower chamber of the airbag.

[0009] According to one embodiment of the present invention, the invention further comprises a plurality of retaining straps interposed between the bracket and the airbag and connecting the bracket and the airbag.

[0010] According to one embodiment of the present invention, the upper chamber includes parallel laterally extending upper first and second sub-chambers, wherein the upper first and second sub-chambers are separated from each other by an upper second seam, and the lower chamber includes parallel laterally extending lower first and second sub-chambers, wherein the lower first sub-chamber and the second sub-chamber are separated from each other by a lower second seam.

[0011] According to one embodiment of the present invention, the sub-chamber of the upper chamber includes an upper fluid connecting channel arranged in the upper second seam, the upper fluid connecting channel is between the upper first and second sub-chambers and fluidly connects the upper first and second sub-chambers, and the sub-chamber of the lower chamber includes a lower fluid connecting channel arranged in the lower second seam, the lower fluid connecting channel is between the lower first and second sub-chambers and fluidly connects the lower first and second sub-chambers.

[0012] According to an embodiment of the present invention, the chambers are all rolled toward the first seam in an unexpanded position.

[0013] According to an embodiment of the invention, the sub-chambers in the expanded position are substantially vertically stacked.

[0014] According to one embodiment of the present invention, a plurality of stabilizing straps are further included between the bracket and the sub-chambers.

[0015] According to an embodiment of the present invention, the trim panel is sized to fit between a vehicle grille and a vehicle bumper.

[0016] According to one embodiment of the invention, the upper chamber extends beyond a leading edge of a vehicle hood in the expanded position, and the lower chamber extends below a vehicle bumper in the expanded position.

[0017] According to the present invention, there is provided an external airbag system, comprising:

[0018] an air bag having an upper chamber and a parallel lower chamber, the upper chamber and the lower chamber being sealingly separated by a transversely extending first seam;

[0019] a bracket connected to the airbag at a first seam, and the bracket includes an upper chute engaging an upper chamber of the airbag and a lower chute engaging a lower chamber of the airbag;

[0020] an inflator fixed relative to the bracket and in fluid communication with the air bag; and

[0021] A trim panel is fixed to the bracket, enclosing the air bag therebetween and having a tear seam substantially aligned with the air bag.

[0022] According to one embodiment of the present invention, the device further comprises a plurality of retaining straps interposed between the bracket and the airbag and connecting the bracket and the airbag.

[0023] According to an embodiment of the present invention, the chambers are all rolled toward the first seam in an unexpanded position.

[0024] According to one embodiment of the present invention, the upper chamber includes parallel laterally extending upper first and second sub-chambers, and the upper first and second sub-chambers are separated from each other by an upper second seam, and the lower chamber includes parallel laterally extending lower first and second sub-chambers, and the lower first and second sub-chambers are separated from each other by a lower second seam.

[0025] According to one embodiment of the present invention, the sub-chamber of the upper chamber includes an upper fluid connecting channel arranged in the upper second seam, the upper fluid connecting channel is between the upper first and second sub-chambers and fluidly connects the upper first and second sub-chambers, and the sub-chamber of the lower chamber includes a lower fluid connecting channel arranged in the lower second seam, the lower fluid connecting channel is between the lower first and second sub-chambers and fluidly connects the lower first and second sub-chambers.

[0026] According to an embodiment of the present invention, the chambers are all rolled toward the first seam in an unexpanded position.

[0027] According to one embodiment of the present invention, a plurality of stabilizing straps are further included between the bracket and the sub-chambers.

[0028] According to an embodiment of the invention, the sub-chambers in the expanded position are substantially vertically stacked.

[0029] According to an embodiment of the present invention, the trim panel is sized to fit between a vehicle grille and a vehicle bumper.

[0030] According to one embodiment of the invention, the upper chamber extends beyond a leading edge of a vehicle hood in the expanded position and the lower chamber extends below a vehicle bumper in the expanded position. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a front elevation view of a vehicle incorporating an external airbag system for pedestrian protection with the airbag in an uninflated position;

[0032] Figure 2 yes Figure 1 An exploded perspective view of the left front corner of the vehicle;

[0033] Figure 3 yes Figure 1 and 2 A perspective view of an external airbag system.

[0034] Figure 4 yes Figure 3 A perspective view of the airbag system viewed from the left rear position to the right front;

[0035] Figure 5 yes Figure 4 A cross-sectional view of the airbag system along the direction of arrow 5 through plane 5S;

[0036] Figure 6 yes Figure 4 A top view of an airbag;

[0037] Figure 7 yes Figure 4 Rear view of the airbag;

[0038] Figure 8 yes Figure 7 An enlarged exploded view of the portion of the airbag in the ellipse 8;

[0039] Fig. 9 yes Figure 8 An enlarged exploded view of the portion of the airbag in the ellipse 9;

[0040] Fig.10 yes Fig. 9 A cross-sectional view of the airbag along the direction of arrow 10 through plane 10S;

[0041] Fig.11 yes Figure 1 A front view of the vehicle with the airbag in an inflated position;

[0042] Fig. 12A , 12B and 12C respectively Fig.11 A cross-sectional view of the airbag along the direction of arrows 12A, 12B and 12C;

[0043] Fig.13 yes Figure 1 and Fig.11 a side view of a vehicle with the airbag in an inflated position;

[0044] Fig.14 yes Figure 1-13 Schematic diagram of the airbag system processing. DETAILED DESCRIPTION

[0045] In this description, relative orientations and directions (for example, upper, lower, bottom, front, rear, front, rear, rear side, outside, inside, inside, exterior, lateral, left side, right side) are not limiting but are provided for the convenience of the reader in describing at least one embodiment of the structure. Such example orientations are from the perspective of a passenger sitting in a seat and facing the dashboard. In the drawings, like reference numerals refer to like parts throughout the several views.

[0046] An external airbag system includes an airbag, a bracket, an inflator, and a trim panel. The airbag has an upper chamber and a parallel lower chamber that are sealingly separated by a transversely extending first seam. The bracket is connected to the airbag at the first seam. The inflator is fixed relative to the bracket and is in fluid communication with the airbag. The trim panel is fixed to the bracket to enclose the airbag therebetween. The trim panel has a tear seam that is substantially aligned with the airbag.

[0047] The bracket may include an upper chute that engages an upper chamber of the airbag and a lower chute that engages a lower chamber of the airbag.

[0048] The external airbag system may include a plurality of tethers interposed between and connecting the carrier and the airbag.

[0049] The upper chamber may include parallel laterally extending upper first and second sub-chambers, wherein the upper first and second sub-chambers are separated from each other by an upper second seam. The lower chamber may include parallel laterally extending lower first and second sub-chambers, wherein the lower first and second sub-chambers are separated from each other by a lower second seam.

[0050] The sub-chamber of the upper chamber may include an upper fluid communication channel disposed in the upper second seam, between the upper first and second sub-chambers and fluidly connecting the upper first and second sub-chambers. The sub-chamber of the lower chamber may include a lower fluid communication channel disposed in the lower second seam, between the lower first and second sub-chambers and fluidly connecting the lower first and second sub-chambers.

[0051] The chamber may be rolled toward the first seam in an unexpanded position.

[0052] The subchambers of the external airbag system may be stacked vertically in the inflated position.

[0053] The trim panel of the external airbag system may be sized to fit between the vehicle grille and the vehicle bumper.

[0054] An upper chamber of the external airbag system may extend beyond a leading edge of a vehicle hood in the inflated position, and a lower chamber of the external airbag system may extend below a vehicle bumper in the inflated position.

[0055] The external airbag system may include a plurality of stabilizing tethers disposed between the carrier and the subchamber.

[0056] refer to Figure 1-14 , the example external airbag system 20 includes an airbag 22, a bracket 24, and a trim panel 26. The airbag 22 can be Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 as well as Fig.10 The unexpanded position (i.e., the undeployed position) shown in FIG. Fig.11 , 12A , 12B, 12C and 13 are unfolded from the expanded position (i.e., the unfolded position).

[0057] The airbag system 20 is shown installed in an example vehicle 28, which is representative of a light and medium truck cab. The airbag system 20 defines a portion of a front fender 30 of the vehicle 28. The front fender 30 is disposed below and in front of a windshield 32 of the vehicle 28. A vehicle hood 34 (i.e., engine cover) is in front of the windshield and may form a portion of the fender 30. A vehicle grille 36 may be incorporated into the fender 30 and may be disposed between the hood 34 and a vehicle bumper 38. A leading edge 39 of the hood 34 is the forward-most edge of the hood 34. A headlamp 40, which also forms a portion of the fender 30, may be adjacent to the grille 36. The airbag system 20 is shown in an example position between the grille 36 and the bumper 38.

[0058] The airbag 22 has an upper chamber 42 that can be deployed in a first direction D1 and a lower chamber 44 that is parallel to the upper chamber 42, and the lower chamber 44 can be deployed in a second direction D2 that is opposite to the first direction D1. The first direction D1 can be a generally upward direction following the grille 36, and the second direction D2 can be a generally downward direction that is perpendicular to the ground and overlaps the bumper 38. In the inflated position, the airbag 22 extends transversely through the front end of the vehicle 28, and extends vertically below the bumper and upward beyond the front edge 39 (i.e., the front upper edge) of the hood 34. The airbag 22 at least substantially covers the fender 30 of the vehicle 28.

[0059] The airbag 22 includes a first or middle seam 46 extending transversely across the entire width of the uninflated airbag 22, the first or middle seam 46 connecting the chambers 42, 44 and sealingly separating the upper chamber 42 from the lower chamber 44. With the middle seam 46 providing a sealed boundary between the upper chamber 42 and the lower chamber 44, if a leak occurs in one chamber, the pressure in the other chamber will remain substantially unaffected. Providing fluid communication between the chambers 42 and 44 will reduce the pressure independence of the chambers, but will still allow the system 20 to function fully. The middle seam 46 separates the upper chamber 42 from the lower chamber 44. The middle seam 46 may or may not coincide with the center of the airbag 22. When the airbag 22 is deployed, the upper chamber 42 and the lower chamber 44 move from the uninflated position to the inflated position, and the middle seam 46 may remain in the same position. The airbag system 20 may include any one or combination of the additional components described in specific embodiments below.

[0060] As best Fig. 12A , 12B As shown in Figures 12C, each upper chamber 42 and lower chamber 44 is divided into first and second parallel sub-chambers extending transversely. Each chamber 42, 44 includes its own sub-chamber. If necessary, more sub-chambers can be used.

[0061] The first subchamber 48 of the upper chamber 42 is adjacent to the middle seam 46. The second subchamber 50 of the upper chamber is adjacent to the first subchamber 48, and the first subchamber 48 is located between the middle seam 46 and the second subchamber 50. The subchambers 48 and 50 are in fluid communication with each other. The subchambers 48 and 50 can be separated from each other by an upper second seam 52. The second seam allows fluid communication between the subchambers 48 and 50. The second seam includes an upper fluid communication channel 54 between the subchambers 48 and 50, and an example fluid communication channel 54 can be provided by a tube (not shown) or a gap in the seam 52. The subchamber 50 may include an accessory chamber 59. The accessory chamber 59 can be positioned to cover the front of the hood 34 in the expanded position.

[0062] Similarly, a first subchamber 56 of the lower chamber 44 is adjacent to the middle seam 46. A second subchamber 58 of the lower chamber 44 is adjacent to the first subchamber 56, wherein the first subchamber 56 is located between the middle seam 46 and the second subchamber 58. The subchambers 56 and 58 are in fluid communication with each other. The subchambers 56 and 58 can be separated from each other by a lower second seam 60. The lower second seam 60 allows fluid communication between the subchambers 56 and 58. The second seam incorporates a lower fluid communication channel 62 between the subchambers 56 and 58, and the example fluid communication channel 62 includes a tube (not shown) or a gap in the seam 60.

[0063] The airbag 22 can be formed from any suitable airbag material, such as a woven polymer. For example, the airbag 22 can be formed from woven nylon yarns, such as nylon 6-6. Other suitable examples include polyether ether ketone (PEEK), polyetherketoneketone (PEKK), polyester, or any other suitable polymer. The woven polymer can include a coating (e.g., silicone, neoprene, polyurethane, etc.). For example, the coating can be a polyorganosiloxane.

[0064] The airbag 22 is secured to the front side 64 of the carrier 24. The airbag 22 may be attached directly (i.e., without intermediate components) to the front side 64, or alternatively may be attached using a retaining tether 66 that connects the airbag to the front side 64. The tether 66 may be formed as part of the airbag 22. When the airbag 22 is directly connected to the front side 64, such connection may be provided between the seam 46 and the front side 64 via stitching, adhesive, etc., as described in more detail below with respect to certain embodiments.

[0065] As best Fig. 9 and 10 As shown, the air bag 22 in an uninflated state is stored in a double rolled orientation with each of the upper chamber 42 and the lower chamber 44 rolled in upon itself. The chambers 42, 44 are each rolled toward the seam 46 in the uninflated position.

[0066] The airbag system 20 includes an inflator 68 fixed to or relative to the bracket 24. The inflator 68 is in fluid communication with the airbag 22. As described in more detail below, when a signal is received from, for example, a system processor 70, the inflator 68 can use an expansion medium (e.g., a gas) to inflate the airbag 22. The inflator 68 can be, for example, a pyrotechnic inflator that uses a chemical reaction to drive the expansion medium to the airbag 22. The inflator 68 can be of any suitable type, such as a cold-gas inflator. A connecting tube 72 can be provided between the inflator 68 and the airbag 22. A single inflator with multiple outlets is designed to ensure appropriate gas flow pressures, inflation rates, etc., however, multiple inflators can be used if desired.

[0067] The bracket 24 is connected to the trim panel 26, capturing the uninflated airbag 22 therebetween. The bracket 24 is secured to the trim panel 26. The bracket 24 may be secured to the trim panel by any conventional attachment means, including heat staking, rivets, threaded fasteners, adhesives, combinations of the foregoing, and the like.

[0068] The bracket 24 may be formed from one or more relatively rigid materials suitable for providing structural support (eg, composite reinforced thermoplastics, sheet steel, cast aluminum, etc.).

[0069] The trim panel 26 is molded from plastic and includes a tear seam 74 and a flexible panel 76 having a reduced thickness on at least one side of the tear seam 74. The tear seam 74 may extend transversely across the entire width of the uninflated air bag 22.

[0070] refer to Figure 1 , 2 , 3 and 5, the trim panel 26 includes a tear seam 74. The tear seam 74 can be designed to tear when subjected to a tension force above a threshold magnitude. In other words, when the force is above the threshold magnitude, the flexible panel 76 on one side of the tear seam 74 separates from the flexible panel 76 on the other side of the tear seam 74. The threshold magnitude can be selected to be greater than the force from, for example, an unintentional push on the trim panel 26 but less than the force from deploying the airbag 22. The tear seam 74 can be, for example, a line of perforation that passes through or nearly through the trim panel 26, a line of plastic that is thinner than the rest of the trim panel 26, etc. Forming the tear seam 74 on the inner surface 82 of the trim panel 26 allows the outer surface 77 of the trim panel 26 to appear as a smooth surface.

[0071] The tear seam 74 may be adjacent to the air bag 22; that is, there is nothing between the tear seam 74 and the air bag 22. The tear seam 74 may be adjacent to the air bag 22 in an uninflated position. During deployment, both the upper chamber 42 and the lower chamber 44 may expand toward and through the tear seam 74.

[0072] refer to Figure 5 , the bracket 24 may include the chute 78, 80. The bracket 24 includes the upper chute 78 adjacent to the upper chamber 42 of the air bag 22 and the lower chute 80 adjacent to the lower chamber 44 of the air bag 22. In other words, there is nothing between the upper chute 78 and the upper chamber 42, and there is nothing between the lower chute 80 and the lower chamber 44. The upper chute 78 may engage with the upper chamber 42, and the lower chute 80 may engage with the lower chamber 44.

[0073] The middle seam 46 can be secured to the bracket 24 between the upper chute 78 and the lower chute 80. The upper chute 78 and the lower chute 80 can abut the air bag 22, i.e., be separated from and contact the air bag 22. The upper chute 78 and the lower chute 80 can be secured to (i.e., directly attached to) an inner surface 82 of the trim panel 26.

[0074] The upper chute 78 and the lower chute 80 may be integrally formed with the bracket 24. The upper chute 78 may be bent upward toward the first direction D1, and the lower chute 80 may be bent downward toward the second direction D2. The upper chute 78 and the lower chute 80 are designed (i.e., sized, shaped, and formed of) selected materials, etc. to guide the upper chamber 42 in the first direction D1 and guide the lower chamber 44 in the second direction D2.

[0075] refer to Fig.13 The airbag system 20 may be equipped with a plurality of stabilizing straps 83 that limit the displacement of the inflated subchambers 48, 50, 56, 58 relative to the bracket 24. Fig.13 The example tether 83 shown in the figure shows the design of the tether for maintaining the shape, size and integrity of the airbag 22 when deployed. The tether 83 extends from the bracket 24 to a selected location on the airbag 22. Although the stabilizing tether 83 shown is shown on the outside of the airbag 22 (i.e., an external tether), the stabilizing tether can be set inside the airbag. Such an internal tether (not shown) can be set between the bracket 24 and the airbag 22 and between the surfaces of the airbag. The location and number of stabilizing tethers can be determined using available engineering analysis tools (such as CAE (computer-aided engineering) analysis).

[0076] refer to Fig.14 , the vehicle 28 may include an inflation system 84. The inflation system 84 includes a processor 70. The processor 70 is programmed to initiate inflation of the airbag 22 in response to a pedestrian approaching. The processor 70 may be embedded in a microcontroller. The microcontroller may include a memory, etc. The memory of the microcontroller may store instructions executable by the processor 70, and the processor 70 may read the instructions from the memory and execute the instructions.

[0077] The vehicle 28 may include a pedestrian sensor 86 that is programmed to detect a pedestrian in the path ahead of the vehicle 28 as part of the PAEB system. The pedestrian sensor 86 may be used to detect a pedestrian in the path ahead of the vehicle 28. The pedestrian sensor 86 may be disposed in the fender 30 or any suitable forward-facing portion of the vehicle 28. The pedestrian sensor 86 may be of various suitable types, such as an ultrasonic sensor, a radar sensor, a visual sensor (e.g., a camera, a lidar), etc. When a pedestrian is in the path of the vehicle 28, the processor 70 may receive one or more signals from the pedestrian sensor 86 indicating the presence of the pedestrian. In response to receiving the signal from the pedestrian sensor 86, the processor 70 may initiate inflation of the airbag 22.

[0078] In order to receive signals from the pedestrian sensor 86 and initiate inflation of the air bag 22, the processor 70 communicates with the pedestrian sensor 86 and the inflator 68, for example, via direct electrical wiring that transmits analog or digital signals or via a communication network, such as a CAN (Control Area Network), Ethernet, LIN (Local Interconnect Network) or any other method.

[0079] In operation, such as Figure 1-10 As shown, under normal operating conditions of the vehicle 28, the airbag 22 is in an uninflated position. When the pedestrian sensor 86 senses a pedestrian in the path of the vehicle 28, the processor 70, as part of the PAEB system, can provide a warning to the driver that intervention is required. If the driver does not take timely action and a possible collision is predicted, the processor 70 will actuate the vehicle's service brakes independently of the driver's input to potentially avoid the collision. The processor 70 can further trigger the inflator 68 to inflate the airbag from the uninflated position to the inflated position using an inflation medium. When the inflator 68 inflates the airbag 22 to the inflated position, the inflation medium flows to the inflation chamber, increasing the pressure in the chambers 42, 44. As the pressure in the chambers 42, 44 increases, the airbag 22 breaks through the tear seam 74 of the trim panel 26, and the panel 76 deflects, extending outward at the rupture seam 74. The chute 78, 80 helps guide the chambers 42, 44 through the tear seam 74. During the inflation process, the upper chamber 42 expands in an upward direction D1 and the lower chamber 44 expands downward D2. The middle seam 46 remains between the bracket 24 and the trim panel 26 when directly connected to the bracket 24. When the middle seam 46 is connected to the bracket 24 by the middle retention tether 66, the middle seam 46 can move through the tear seam 74 and move to the outside of the trim panel 26. When the air bag 22 expands, the stabilizing tether 83 limits the expansion of the chambers 42, 44 and their corresponding sub-chambers 48, 50, 56, 58. The air bag 22 in the inflated position provides coverage to the front of the fender 30 and the hood 34 to absorb the impact energy of the pedestrian's knee and head, potentially reducing injuries.

[0080] The shape of the inflated airbag 22 resembles a ladder because the seams defining the subchambers 48, 50, 56, 58 further define the stepped surface of each subchamber 48, 50, 56, 58. Fig.11, the ladder configuration allows the airbag 22 to substantially cover all possible pedestrian impact areas at the front end of the vehicle 28. The ladder configuration also allows the airbag 22 to fully inflate with a 40% to 50% smaller inflation medium volume than an airbag without seams 46, 52, 60.

[0081] The use of a double wrap design allows the lower chamber 44 to deploy downward to promote calf impact protection and allows the upper chamber 42 to deploy upward to promote thigh and pelvis and head impact protection. The disclosed system 20 also allows for the elimination of calf reinforcements (deployable or swingable), cross-vehicle grille reinforcements, pedestrian-friendly hood latches, and other front end structural modifications for pedestrian protection.

[0082] As used herein, the adverb "substantially" means that the shape, structure, measurement, quantity, time, etc. may deviate from the precisely described geometry, distance, measurement, quantity, time, etc. due to imperfections in materials, processing, manufacturing, data transmission, computing speed, etc.

[0083] The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than limitation. Many modifications and variations of the disclosure are possible in light of the above teachings, and the disclosure may be practiced in ways other than those specifically described.

Claims

1. An external airbag system, comprising: an air bag having an upper chamber and a parallel lower chamber, the upper chamber and the lower chamber being sealingly separated by a transversely extending first seam; a bracket connected to the airbag at the first seam; an inflator fixed relative to the bracket and in fluid communication with the airbag; and a decorative panel fixed to the bracket, enclosing the air bag therebetween and having a tear seam substantially aligned with the air bag; The lower chamber comprises a parallel transversely extending lower first sub-chamber and a lower second sub-chamber, wherein the lower first sub-chamber and the lower second sub-chamber are separated from each other by a lower second seam; The lower first subchamber extends along the bumper in a vehicle front direction of the bumper; The lower second subchamber includes an upper end extending along the bumper in a vehicle front direction of the bumper, the lower second subchamber extending vertically below the bumper in the expanded position; The first lower subchamber and the second lower subchamber each have a frontmost portion in a vehicle front direction, the frontmost portions of the first lower subchamber and the second lower subchamber being flat and vertical in an expanded position; The upper chamber extends upward from the lower chamber and extends rearward along the hood, the upper chamber having a frontmost portion extending upward relative to the lower chamber and toward the rear of the vehicle.

2. The external airbag system according to claim 1, wherein: The bracket includes an upper chute that engages the upper chamber of the airbag and a lower chute that engages the lower chamber of the airbag. 3 . The external airbag system of claim 1 , further comprising a plurality of retaining tethers interposed between and connecting the bracket and the airbag.

4. The external airbag system according to claim 1, wherein: The trim panel is sized to fit between a vehicle grille and a vehicle bumper.

5. The external airbag system according to claim 1, wherein: The upper chamber includes parallel transversely extending upper first sub-chamber and upper second sub-chamber, wherein the upper first sub-chamber and the upper second sub-chamber are separated from each other by an upper second seam.

6. The external airbag system according to claim 5, wherein: The sub-chamber of the upper chamber includes an upper fluid connecting channel arranged in the upper second seam, the upper fluid connecting channel is between the upper first sub-chamber and the upper second sub-chamber and fluidly connects the upper first sub-chamber and the upper second sub-chamber, and the sub-chamber of the lower chamber includes a lower fluid connecting channel arranged in the lower second seam, the lower fluid connecting channel is between the lower first sub-chamber and the lower second sub-chamber and fluidly connects the lower first sub-chamber and the lower second sub-chamber.

7. The external airbag system of claim 6, further comprising a plurality of stabilizing tethers disposed between the bracket and the subchamber.

8. The external airbag system according to claim 1, wherein: The chambers are each rolled toward the first seam in an unexpanded position.

9. The external airbag system of claim 1, wherein: The upper chamber extends beyond a leading edge of a vehicle hood in the expanded position.

10. The external airbag system according to claim 9, wherein: The upper chamber includes an accessory chamber positioned to cover a portion of the vehicle hood in the expanded position.

11. An external airbag system comprising: an air bag having an upper chamber and a parallel lower chamber, the upper chamber and the lower chamber being sealingly separated by a transversely extending first seam; a bracket connected to the airbag at a first seam, and the bracket includes an upper chute engaging an upper chamber of the airbag and a lower chute engaging a lower chamber of the airbag; an inflator fixed relative to the bracket and in fluid communication with the airbag; and a decorative panel fixed to the bracket, enclosing the airbag therebetween and having a tear seam substantially aligned with the airbag; The lower chamber comprises a parallel transversely extending lower first sub-chamber and a lower second sub-chamber, wherein the lower first sub-chamber and the lower second sub-chamber are separated from each other by a lower second seam; The lower first subchamber extends along the bumper in a vehicle front direction of the bumper; The lower second subchamber includes an upper end extending along the bumper in a vehicle front direction of the bumper, the lower second subchamber extending vertically below the bumper in the expanded position; The first lower subchamber and the second lower subchamber each have a frontmost portion in a vehicle front direction, the frontmost portions of the first lower subchamber and the second lower subchamber being flat and vertical in an expanded position; The upper chamber extends upward from the lower chamber and extends rearward along the hood, the upper chamber having a frontmost portion extending upward relative to the lower chamber and toward the rear of the vehicle.

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