Roof-mounted occupant restraint system

Abstract

A restraint system for helping to protect an occupant of a vehicle having a roof and a passenger compartment having a seat for the occupant, the restraint system including an airbag mounted on the roof of the vehicle. The airbag has a stored state and is inflatable to a deployed state, the airbag having a forward-facing occupant-receiving portion and an opposite rearward-facing portion facing away from the occupant. The airbag has one or more connections with the roof of the vehicle, wherein the airbag and the connections are configured such that the roof acts as a reaction surface for supporting the airbag from moving in response to an occupant in forward motion impacting the occupant-receiving portion. The system does not rely on the rearward-facing portion of the airbag engaging and using the vehicle structure to support the airbag from moving in response to an impacted occupant.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 661,667, filed April 24, 2018, and U.S. Provisional Application No. 62 / 636,899, filed March 1, 2018, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates generally to vehicle airbags, and more specifically to roof-mounted airbags that rely on the roof as a reaction surface. Background Technology

[0004] Inflatable vehicle occupant protection devices (such as airbags) are known to help protect vehicle occupants. One particular type of airbag is a frontal airbag that inflates between the front seat occupant and the vehicle's dashboard. Such airbags can be driver airbags or passenger airbags. When inflated, driver and passenger airbags help protect occupants from impacts with vehicle components (e.g., the vehicle's dashboard and / or steering wheel).

[0005] Typically, passenger airbags are stored in a deflated state in a housing mounted on the vehicle's dashboard. An airbag door may be attached to the housing and / or dashboard to help enclose and conceal the airbag in its stored state. When the passenger airbag deploys, the airbag door opens to allow the airbag to move into its inflated state. The opening of the airbag door is a result of the force exerted on the door by the airbag's inflation.

[0006] Typically, the driver's airbag is stored in a deflated state in a housing mounted on the vehicle's steering wheel. An airbag cover may be attached to the housing and / or the steering wheel to help enclose and conceal the airbag in its stored state. When the driver's airbag deploys, the airbag cover opens to allow the airbag to move into its inflated state. The opening of the airbag cover is a result of the force exerted on the cover as the driver's airbag inflates.

[0007] There's a trend in the automotive industry towards making vehicles more spacious. Styling has already resulted in smaller dashboards, and therefore further away from the occupants. Looking ahead, driverless, autonomous vehicles will be even more spacious. Autonomous vehicles have been considered for some time, and their mass adoption is now approaching. Autonomous vehicles can eliminate certain structural features.

[0008] In this context, the paradigm for occupant safety systems must shift. In the past, the necessity of a vehicle operator / driver led to a certain standard vehicle cabin configuration. In the United States, the driver was the forward-facing occupant in the left front seat with access to vehicle controls and instruments (steering wheel, pedals, dashboard, console, etc.). This driver configuration helped determine the layout of the rest of the vehicle (forward-facing passenger-side occupants in the front seats, forward-facing occupants in the rear seats (second row, third row, etc.)). Therefore, in the past, typically, this cabin layout, along with the associated occupant positions and orientations, were considered when designing occupant safety systems.

[0009] Autonomous vehicles eliminate the need for an operator / driver, thus eliminating the need for conventional positioning and orientation of the operator / driver. Vehicle manufacturers are free to utilize the passenger space as they see fit, without being constrained by predetermined passenger arrangements (e.g., all occupants facing forward) or vehicle structural configurations (e.g., steering wheel / dashboard configuration, center console configuration, footwell pedal controls, etc.).

[0010] This presents not only the challenge of where to place the airbag system, but also the challenge of finding a reactive surface against which the airbag rests so that it can absorb the impact. Typically, front airbags mounted on the dashboard and steering wheel utilize these structures as reactive surfaces so that the airbag can resist, mitigate, and absorb the impact energy of an occupant in an impact and provide the desired ride-down effect. However, in autonomous vehicles, the vehicle may not have a dashboard or steering wheel at all, and occupants may be positioned and oriented in unconventional ways. This may make it difficult or impossible to utilize traditional vehicle structures as reactive surfaces. Summary of the Invention

[0011] According to one aspect, a restraint system for aiding in the protection of occupants of a vehicle, the vehicle having a roof and a passenger compartment with seats for occupants, the restraint system including an airbag mounted on the vehicle roof. The airbag has a stored state and is inflatable to a deployed state. After deployment, the airbag has a forward-facing occupant receiving portion and an opposite rearward-facing portion facing away from the occupants. The airbag has one or more connections to the vehicle roof, wherein the airbag and the connections are configured such that the roof serves as a reaction surface for supporting the airbag against movement in response to an occupant impacting the occupant receiving portion during forward movement. The system does not rely on the rearward-facing portion of the airbag engaging the vehicle structure and uses the vehicle structure as a reaction surface for supporting the airbag against movement in response to an occupant impacting the occupant receiving portion during forward movement.

[0012] According to another aspect, a restraint system for helping to protect occupants of a vehicle, the vehicle having a roof and a passenger compartment with seats for occupants, the restraint system including an airbag mounted on the vehicle roof. The airbag has a stored state and is inflatable to a deployed state. After deployment, the airbag has a first end, a second end, and an intermediate portion connected to the roof. The airbag is connected to the roof such that the roof serves as a reaction surface to support the airbag from movement in response to an occupant sinking into the airbag during forward movement, wherein the intermediate portion does not engage with the vehicle structure in response to an occupant sinking into the airbag.

[0013] According to another aspect, alone or in combination with any other aspect, there is at least one tether having a first end connected to the airbag and a second end connected to the vehicle roof. The at least one tether is configured to transfer energy from an occupant trapped in the airbag to the vehicle roof.

[0014] According to another aspect, alone or in combination with any other aspect, the airbag is configured to be positioned in front of the vehicle occupants, and the second end of the tether is configured to be connected to the vehicle roof behind the vehicle occupants.

[0015] According to another aspect, alone or in combination with any other aspect, the airbag is configured to pivot about the connection between the airbag and the vehicle roof in response to the action of an occupant during an impact. The upper portion of the airbag is configured to engage the vehicle roof such that the vehicle roof serves as a reaction surface for restraining the movement of the airbag in response to an occupant sinking in.

[0016] According to another aspect, alone or in combination with any other aspect, at least one tether has a first end connected to the airbag and a second end connected to the vehicle roof at the location where the airbag is installed. The at least one tether is configured to transfer energy from an occupant trapped in the airbag to the vehicle roof.

[0017] According to another aspect, alone or in combination with any other aspect, the second end of the tether is configured to be connected to the airbag module, the airbag being housed in the airbag module in the storage state.

[0018] According to another aspect, alone or in combination with any other aspect, the airbag and tether are configured such that the tether limits the distance that the lower portion of the airbag can move away from the vehicle roof, thereby introducing a bend in the receiving portion of the airbag, the bend being concave in the path along which the occupant travels and comes into contact with the airbag.

[0019] According to another aspect, alone or in combination with any other aspect, due to the bending, the fabric of the receiving portion that the occupant travels into contact with has reduced surface tension.

[0020] According to another aspect, alone or in combination with any other aspect, the airbag includes at least one internal tether for shaping the receiving portion.

[0021] According to another aspect, alone or in combination with any other aspect, the at least one internal tether helps reduce the surface tension on the fabric of the receiving portion.

[0022] According to another aspect, alone or in combination with any other aspect, the at least one internal tether helps to create a bag for receiving the occupant.

[0023] According to another aspect, alone or in combination with any other aspect, the airbag has a generally U-shaped configuration including spaced-apart branches. The airbag is configured to pivot about the connection between the airbag and the vehicle roof in response to occupant slumping. The upper portion of at least one of the branches is configured to engage the vehicle roof such that the vehicle roof serves as a reaction surface for restraining the movement of the airbag in response to occupant slumping.

[0024] According to another aspect, alone or in combination with any other aspect, the branches are interconnected by tethers. Inflation of the airbag forces the branches to move away from each other, and this movement is limited by the tethers. Forcing the branches away from each other preloads them to prevent them from deflecting in response to the airbag engaging the roof.

[0025] According to another aspect, alone or in combination with any other aspect, the airbag constitutes a curtain airbag that spans the passenger compartment. The restraint system further includes at least one tether having a first end connected to the curtain airbag and a second end connected to the vehicle. The at least one tether is configured to transfer energy from an occupant's entrapment to the vehicle.

[0026] According to another aspect, alone or in combination with any other aspect, the tether is connected to at least one of the vehicle roof and side structures of the vehicle.

[0027] According to another aspect, alone or in combination with any other aspect, the airbag constitutes a plurality of horizontally extending chambers in the vehicle. The restraint system further includes a shaped piece that supports the chambers and tethers that connect the shaped piece to the vehicle. The shaped piece is configured to arrange the chambers in a curved configuration when viewed in outline.

[0028] According to another aspect, alone or in combination with any other aspect, the chamber is arranged convexly toward the occupant.

[0029] According to another aspect, alone or in combination with any other aspect, the chamber is arranged concavely toward the occupant.

[0030] According to another aspect, alone or in combination with any other aspect, the restraint system is configured to use only the roof as the reaction surface.

[0031] According to another aspect, alone or in combination with any other aspect, the airbag includes a first portion and a U-shaped second portion, the first portion extending along the roof of the vehicle, the second portion extending toward the occupant and having a first branch extending from the first portion and a second branch connected to the first branch. The second branch moves to engage with the first branch in response to the occupant sinking in.

[0032] According to another aspect, alone or in combination with any other aspect, at least one tether is connected to the first branch and the roof, the at least one tether being used to restrict movement of the first branch in response to the second branch engaging the first branch.

[0033] According to another aspect, alone or in combination with any other aspect, the sensor senses the occurrence of an event in which the airbag is expected to deploy and generates a signal indicating the occurrence of the event. A controller is connected to the sensor and, in response to receiving the signal, actuates an inflation device to inflate the airbag to the deployed state.

[0034] Other objects and advantages of the invention, as well as a more complete understanding of the invention, will become apparent from the following detailed description and accompanying drawings. Attached Figure Description

[0035] Figure 1 It is a top view of a vehicle including an exemplary occupant restraint system mounted on the roof.

[0036] Figure 2 This is a schematic diagram of the passenger compartment of a vehicle with an exemplary airbag in a stored state, having a first seating arrangement and restraint system.

[0037] Figure 3A It is a schematic display of the passenger compartment of a vehicle with airbags in the deployed state.

[0038] Figure 3B yes Figure 3A An enlarged cross-sectional view of a portion of the airbag.

[0039] Figure 4This is a schematic representation of another exemplary airbag in its deployed state.

[0040] Figure 5 This is a schematic representation of another exemplary airbag in its deployed state.

[0041] Figure 6A This is a schematic representation of another exemplary airbag in its deployed state.

[0042] Figure 6B yes Figure 6A A top view of the deployed airbag.

[0043] Figure 7 This is a schematic diagram of the passenger compartment of a vehicle with another exemplary airbag in a stored state, having a second seating arrangement and restraint system.

[0044] Figure 8 It is in the unfolded state. Figure 7 A schematic illustration of an airbag.

[0045] Figure 9A This is a schematic representation of another exemplary airbag in its deployed state.

[0046] Figure 9B yes Figure 9A Front view of the airbag.

[0047] Figure 10 This is a schematic representation of another exemplary airbag in its deployed state.

[0048] Figure 11 This is a schematic representation of another exemplary airbag in its deployed state.

[0049] Figure 12 This is a schematic representation of another exemplary airbag in its deployed state. Detailed Implementation

[0050] The present invention relates generally to vehicle airbags, and more specifically to roof-mounted airbags that rely on the roof as a reaction surface. Figure 1 and Figure 2 An exemplary vehicle safety system in the form of an occupant restraint system 10 is shown. A vehicle 20 extends along a centerline 22 from a first end or front end 24 to a second end or rear end 26. The vehicle 20 extends to a left side portion 28 and a right side portion 30 on opposite sides of the centerline 22. The first end 24 of the vehicle 20 includes a dashboard 42 facing the passenger compartment or passenger cabin 40. A windshield or deflector 44 may be located between the dashboard 42 and the roof 32.

[0051] Vehicle 20 can be an autonomous vehicle, in which case passenger compartment 40 may be without operator controls (e.g., steering wheel, pedals, instrument panel, center console, etc.). Therefore, dashboard 42 can be reduced in size or completely removed to maximize space in passenger compartment 40.

[0052] Seat 50 is positioned within passenger compartment 40. In this open passenger compartment 40 configuration, vehicle seats 50 can be configured, positioned, and arranged in various ways, without being constrained by the need for convenience for the vehicle driver / operator. For example, in Figure 2 In this configuration, the seats 50 can be arranged in a forward-facing configuration, with the front row 52 and the rear row 54 arranged in a manner similar to that of a conventional vehicle. It should be understood that the vehicle 20 may alternatively include more or fewer rows of seats 50 (not shown). Regardless, each seat 50 is equipped with a seatbelt 56 to restrain its occupant 60.

[0053] for Figure 2 In a conventional, forward-facing seating arrangement, in the event of a frontal collision, the occupants 60 of the front 52 and rear 54 are restrained by their respective seat belts 56. However, additional restraints are required for head and neck support. Typically, this additional protection is provided at least for the front occupant 52 by an airbag mounted on the dashboard. However, in Figure 2 In the autonomous vehicle 20, the dashboard may be reduced in size and / or completely removed. For example, control interfaces for climate control, GPS, navigation, entertainment, etc., may be provided in the central console area of ​​the vehicle 20 between the occupants 60 in the front row 52 and / or the rear row 54.

[0054] This means that since the front row 52 does not need to be adjacent to the dashboard 42 or the area where the dashboard is normally located, there can be a significant amount of space between the front row 52 and the front passenger compartment structure facing the front. Therefore, deploying the airbag from this location may not be effective due to the large volume required. This will present problems in determining the dimensions of the airbag(s) and inflator(s) for such a large volume, and may also present problems in deploying the airbag(s) to such a large volume within the necessary short time required to protect occupants in a collision.

[0055] Therefore, it is evident that the various passenger seating configurations realized by autonomous vehicles may pose challenges to the traditional concept of airbag protection. Furthermore, the lack of typical vehicle architectures (e.g., dashboards) to serve as reaction surfaces presents an additional challenge, as airbags require structures (e.g., reaction surfaces) to support the deployed airbag in response to occupant entrapment.

[0056] With this in mind, Figures 1 to 2The occupant safety system 10 shown includes at least one vehicle occupant protection device in the form of an inflatable airbag 70 mounted in the roof 32 of the vehicle 20. Mounting the airbag 70 in the vehicle roof 32 is convenient because the airbag can be positioned at a desired distance from the occupants(s) ...(s))(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s))(s)(s)(s)(s)(s)(s))(s)(s)(s)(s)(s)(s)(s))(s)

[0057] Airbag 70 is housed / concealed within the roof structure of vehicle 20, for example, behind headliner 72. Airbag 70 undergoes at least one of rolling up and folding before being placed behind headliner 72. The rolled-up airbag 70 may be housed in a cover or housing / module 68, which is then placed behind headliner 72. Occupant restraint system 10 also includes an inflation device 74 positioned in each module 68 for supplying inflatable gas to each airbag 70. Inflation device 74 is operably (e.g., via wiring) connected to airbag controller 80 (see...). Figure 2 The airbag controller includes or communicates with one or more collision sensors (not shown). The airbag controller 80 is operable to determine the occurrence of a collision event and actuate the inflator 74 in a known manner to inflate the airbag 70. The inflator 74 can be of any known type, such as a gas-storage type, a solid propellant type, a pressurized type, or a hybrid type.

[0058] The airbag 70 can be constructed from any suitable material, such as nylon (e.g., textile nylon 6-6 yarn), and can be constructed in any suitable manner. For example, the airbag 70 may include one or more material pieces or inserts. If more than one material piece or insert is used, these material pieces or inserts can be interconnected in known ways (e.g., stitching, ultrasonic welding, thermal bonding, or adhesive) to form the airbag 70. The airbag 70 can be uncoated, coated with a material (e.g., impermeable urethane), or laminated with a material (e.g., an impermeable membrane). Thus, the airbag 70 can have an airtight or substantially airtight construction. Those skilled in the art will recognize that alternative materials (e.g., polyester yarn) and alternative coatings (e.g., silicone) can also be used to construct the airbag 70.

[0059] The occupant restraint system 10 may include a plurality of airbags 70 disposed along the roof 32 and within the headliner 72 at a position associated with and aligned with each seat 50 in each row 52, ​​54. In other words, each seat 50 in the vehicle 20 may have a separate module 68 (with a corresponding airbag 70 and inflator 74) associated with and aligned with it. In each case, the airbags 70 are positioned in front of the associated seat 50 in each row 52, ​​54 in the direction that the occupants 60 in these seats will be facing (i.e., in front of the front row 52 and in front of the rear row 54).

[0060] The airbag 70 extends in the left-right direction of the vehicle 20 and is approximately parallel to the width of the seat 50. Figure 2 In the example shown, airbags 70 are positioned behind the headliner 72 and are each associated with a single seat 50 in each row 52, ​​54. Alternatively, a single airbag 70 may span the entire width of the passenger compartment 40 to protect all passengers 60 (not shown) in an entire row 52 or 54. Since the airbags in each exemplary configuration described herein are identical for each row in the vehicle 20, for the sake of brevity, the construction and operation of airbags associated only with the seats 50 in the rear row 54 will be discussed.

[0061] like Figure 3A As shown, upon sensing an event that would cause the airbag 70 to inflate (e.g., a vehicle collision), the controller 80 provides a signal to the inflator 74. Upon receiving the signal from the controller 80, the inflator 74 is actuated and supplies inflation fluid to the inflatable volume of the airbag 70 in a known manner. The inflating airbag 70 applies force to the headliner 72, causing the headliner to open (e.g., via a tear or door). This releases the airbag 70 to inflate and deploy from a stored state behind the headliner 72 to a deployed state extending into the passenger compartment 40, in front of and aligned with the seat 50 in the rear sill 54. The airbag 70 helps protect the occupants of the rear sill 54 by absorbing the impact of the airbag while inflating.

[0062] After deployment, the airbag 70 extends from the upper end 82 to the lower end 84 and defines an inflatable volume 90. A middle portion 86 is disposed between the upper end 82 and the lower end 94. The upper end 82 is connected to the vehicle 20 and fluidly connected to the inflation device 74. The lower end 84 is positioned near the occupant 60 in the rear seat 54. A forward-facing receiving surface or portion 88 faces the occupant 60. Conversely, a rearward-facing surface or portion 89 faces away from the occupant 60.

[0063] The airbag 70 includes an upper portion 92 defining an upper inflatable chamber 94. Figure 3B The lower portion 96 of the airbag 70 defines a lower inflatable chamber 98 (see...). Figure 3BThe folded portion 100 extends to a depth d into the inflatable volume 90 towards the inner wall 102 of the airbag 70. The folded portion 100 separates the upper inflatable chamber 94 and the lower inflatable chamber 98 and is formed as an inverted arch portion of the airbag 70 material. The folded portion 100 forms a limiting portion 104 or a reduced cross-sectional area of ​​the airbag 70 between the chambers 94 and 98, and serves as a recess for reducing the load on the airbag.

[0064] A tether 110 connects the folded portion 100 to the inner wall 102 to maintain the folded portion 100 in an arched state. For this purpose, the tether 110 extends between a pair of ends 112 and includes a portion 114 between the ends, fastened to the arched folded portion 100. The tether 110 is formed from a single piece of non-stretchable material. Alternatively, the tether 110 may be formed as two parts, each including one end of the ends 112 and fastened to the folded portion 100. In any case, the folded portion 100 formed by the tether 110 can improve the protection of the occupant 60 by providing an enhanced degree of cushioning for the occupant's upper torso and / or head 62.

[0065] As noted, there is no vehicle structure in a suitable position to serve as a reaction surface to restrain the movement of the deployed airbag 70. That is to say, the roof tether 120 ( Figure 3A The airbag 70 can be supported to prevent movement in response to the occupant 60 sinking in. More specifically, the roof tether 120 replaces the reaction surface typically required for a frontal passenger airbag. For this purpose, a pair of roof tethers 120 can be provided for the airbag on the inner and outer sides of the airbag 70, on opposite sides of the occupant 60. Each roof tether 120 extends from a first end 122 connected to the roof 32 to a second end 124 connected to the lower end 84 of the airbag 70. The first end 122 of the roof tether 120 is connected to the vehicle 20 behind the airbag 70, the occupant 60, and the vehicle seat 50. The second end 124 may be configured or include a stress reducer for distributing the connection between the tether 120 and the airbag 70 over a large surface of the airbag fabric to prevent tearing.

[0066] Because occupant 60 is wearing a seatbelt, a frontal collision that causes the occupant to move forward results in the occupant bending at the waist and following an angled or arc-shaped path toward the airbag receiver 88, such as... Figure 3A As generally indicated by arrow F. Once the moving occupant 60 engages the inflated lower portion 96, the airbag 70 is forced to move in direction F. Roof tethers 120, connected to the roof 32 and the lower end 84, prevent the airbag 70 from moving in direction F.

[0067] Advantageously, such as Figure 3AAs shown, the position of the first end 122 / roof 32 connection can be selected such that the roof tether 120 extends in a direction or along a path that approximates or coincides with (i.e., is substantially parallel to or extends along with) the path along which the occupant 60 travels and comes into contact with the airbag 70. In this way, the tension applied to the airbag 70 by the roof tether 120 can be opposite to the impact force applied to the airbag by the fallen occupant 60. As a result, the roof 32, via the roof tether 120, serves as a reaction surface for the airbag 70. The airbag 70 thus provides a cushioning effect for the moving occupant 60, thereby helping to reduce the load on the occupant. For this purpose, the airbag 70 receives the moving occupant 60 by providing a gentler reaction force in response to the occupant falling. Therefore, Figures 3A to 3B The exemplary configuration does not require interaction with the front structure of the vehicle 20 (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag 70.

[0068] Figure 4 Another exemplary configuration of the occupant restraint system 10a is shown. Figure 4 In this configuration, the airbag module 68 includes an airbag 70a and tethers 140 that are self-contained within the airbag module. The tethers 140 are self-contained because they are integrated with the airbag module 68 and can therefore be easily installed into the vehicle 20 by mounting the module in the roof 32.

[0069] After deployment, the airbag 70a extends from the upper end 130 to the lower end 132 and defines an inflatable volume 134. A middle portion 135 is disposed between the upper end 132 and the lower end 134. The upper end 130 is connected to the vehicle 20 and fluidly connected to the inflator 74. The lower end 132 is positioned near an occupant 60 in the rear seat 54. The airbag 70a also includes a forward-facing receiving surface or portion 136 facing the occupant 60. A contrasting rearward-facing portion or surface 138 faces away from the occupant 60.

[0070] A self-accommodating tether 140 supports the airbag 70a to prevent it from moving in response to the occupant 60 sinking in. The self-accommodating tether 140 extends from a first end 142 of a structure (e.g., housing) connected to the airbag module 68. The first end 142 is thus indirectly connected to the roof 32. A second end 144 of the tether 140 is connected to the lower end 132 of the airbag 70a. As shown, the second end 144 is connected to the portion of the lower end 132 facing the occupant 60 (i.e., the tether 140 is positioned substantially entirely between the occupant 60 and the airbag 70a).

[0071] The tether 140 limits the distance the lower end 132 of the airbag 70a can move away from the vehicle roof 32. As a result, as the airbag 70a deploys, the tether 140 causes an upward / reverse bend or fold within the lower end 132 of the airbag. Advantageously, as... Figure 4 As shown, the tether 140 can be configured such that the bend of the lower end 132 appears in the path of the occupant 60 as it travels and comes into contact with the airbag 70a. In other words, the occupant-facing surface 136 can have a concave shape in response to the tether 140 restricting the deployment of the airbag 70a.

[0072] Furthermore, the deformation of the lower end 132 of the airbag 70a caused by the tether 140 allows the fabric of the occupant-facing surface 136 of the airbag to have a lower surface tension. In this way, the occupant-facing surface 136 provides a softer surface for the impacted occupant 60 and tends to wrap around and support the occupant during the cushioning process in the forward / downward direction F. The tension applied to the airbag 70a by the self-accommodating tether 140 can at least partially or substantially resist the impact force exerted on the airbag by the trapped occupant 60, and thus provide the desired cushioning characteristics. In this way, the roof 32 serves as a reaction surface for the airbag 70a via the tether 140.

[0073] Furthermore, the impact of the airbag 70a on the occupant 60 can cause the entire airbag to pivot in mode R around the connection between the airbag and the roof 32 at the airbag module 68. When this occurs, the upper end 130 of the airbag 70a engages the roof 32 and further serves as a reaction surface for the airbag 70a by preventing additional rotation in mode R. For these reasons, Figure 4 The exemplary airbag 70a configuration does not require interaction with the vehicle’s front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0074] Figure 5 Another exemplary configuration of the occupant restraint system 10b is shown. Figure 5 In this configuration, the airbag module 68 includes an airbag 70b and a self-contained tether 168. The airbag 70b, when deployed, has a generally U-shaped configuration and extends from an upper end 150 to a lower end 152, defining an inflatable volume 166. A middle portion 154 is disposed between the upper end 150 and the lower end 152. A forward-facing receiving surface or portion 156 faces the occupant 60. Conversely, a rearward-facing surface or portion 158 faces away from the occupant 60.

[0075] The airbag 70b includes a pair of spaced-apart branches 160, 162 connected by a lower portion 164. Branch 160 is connected to the airbag module 68 and receives inflation fluid from the inflation device 74. Branch 162 forms the free end of the airbag 70b. Branches 160, 162 terminate near the roof 32. The lower portion 164 is positioned closer to the occupant 60.

[0076] Compared to a single-chamber construction with the same external perimeter area, the U-shaped airbag 70b has a smaller inflatable volume 166, while using more airbag fabric to define the inflatable volume. Because the branches 160, 162 of the U-shaped airbag 70b have a relatively small thickness, they have a high surface area to volume ratio. This makes the branches 160, 162 relatively rigid after inflation.

[0077] The tether 168 connects branches 160 and 162 to each other at the upper end 150 of the airbag 70b. In one example, the tether 168 is positioned on both the inner and outer sides of the airbag 70b.

[0078] The airbag 70b is constructed such that, during inflation, branches 160 and 162 tend to move away from each other (i.e., in the forward / rearward direction of vehicle 20). The tether 168 is configured to prevent this movement, thereby becoming taut against the forces exerted by branches 160 and 162. In other words, the tether 168 inhibits the branches 160 and 162 from moving away from each other, and these branches are particularly hindered from moving toward each other due to the pressurized inflation fluid within them. This preloads branches 160 and 162 to prevent them from moving toward each other.

[0079] Due to this configuration, the upper portion 163 of branch 162 is configured to engage the upper portion of the vehicle structure, such as the roof 32 and / or windshield 44 near the roof (when the airbag is associated with the seat 50 of the front row 52), in response to the occupant 60 falling into the receiving portion 156 of the airbag 70b. In this way, the roof 32 serves as the reaction surface of the airbag via the tether 168 and the upper portion 163 of the airbag 70b. As a result, in response to the falling occupant 60, the engagement of the upper portion 163 with the reaction surface (i.e., the roof 32 and / or windshield 44), combined with the preloaded branches 160, 162, creates a corresponding resistance to further pivoting movement of the airbag in manner R.

[0080] For these reasons, airbag 70b can at least partially or substantially resist the impact force exerted on the airbag by the trapped occupant 60, and thus provide the desired cushioning characteristics. Figure 5 The exemplary configuration of the airbag 70b therefore does not require interaction with the vehicle’s front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0081] Figures 6A to 6B Another exemplary configuration of the occupant restraint system 10c is shown. In this configuration, the airbag module 68 includes an airbag 70c and a tether 174. The airbag 70c, after deployment, has a generally elongated rectangular shape and extends from an upper end 170 to a lower end 172, defining an inflatable volume 173. The upper end 170 is connected to the airbag module 68 and receives inflation fluid from an inflation device 74. The lower end 172 is positioned close to the occupant 60. A middle portion 171 is disposed between the upper end 170 and the lower end 172. A forward-facing receiving surface or portion 175 faces the occupant 60. Conversely, a rearward-facing surface or portion 177 faces away from the occupant 60.

[0082] Airbag 70c is a curtain airbag, which has a smaller thickness compared to a conventional front airbag when measured in the direction of travel of vehicle 20. Airbag 70c may have a similar configuration to side impact curtain airbags, which deploy along the side structure of the vehicle in the event of a side impact and / or vehicle rollover. Curtain airbag 70c extends laterally across the width of vehicle 20 (i.e., in the inward and outward directions) and thus helps protect all occupants 60 in the rear seats 50 of the rear sill 54.

[0083] The structure by which the tether 174 connects the opposite sides of the airbag 70c to the left and right sides 28 and 30 of the vehicle 20 is ( ). Figure 6B In one example, the tether 174 can connect the airbag 70c to a vehicle side wall, door, or pillar (e.g., B-pillar, C-pillar, D-pillar), etc. For this purpose, each tether 174 includes a first end 176 connected to one of the sides 28, 30 of the vehicle 20 and a second end 178 connected to one of the lateral sides of the airbag 70c. The second end 178 may be configured or include a stress reducer to ensure that the connection between the tether 174 and the airbag 70c is laid on a large surface of the airbag fabric to prevent tearing. In any case, the tether 174 can help hold the airbag 70c at a desired position or height within the vehicle 20. For example, the tether 174 can position the airbag 70c at a slightly rearward angle within the vehicle 20, such as... Figure 6A As shown in the figure.

[0084] The first end 176 / vehicle 20 connection may be laterally positioned and / or positioned behind the occupant-facing surface of the airbag 70c. For example, it may be used in a rear connection position, wherein a structure (e.g., a vehicle strut) for anchoring the first end 176 of the tether 174 is positioned behind the airbag 70c.

[0085] Advantageously, such as Figure 6AAs shown, the tether 174 positions the airbag 70c orthogonal to the path along which the occupant 60 travels and contacts the airbag. This places the receiving portion 175 of the airbag 70c in an ideal position for receiving the occupant 60. Simultaneously, the tether 174 supports the airbag 70c against the impact force exerted on it by the trapped occupant 60. As a result, the roof 32 serves as a reaction surface for the airbag 70c via the tether 174 and the side structure of the vehicle 20. Therefore, Figures 6A to 6B The 70c configuration of the airbag does not require interaction with the front structure of the vehicle 20 (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0086] Figures 7 to 8 Another exemplary configuration of the occupant restraint system 10d is shown. In this configuration, the airbag module 68 includes an airbag 70d and a tether 180, and the seating arrangement is unconventional. In particular, Figures 7 to 8 The vehicle 20 is shown with two rows of seats 50 facing each other, with the front row 52 facing rearward and the rear row 54 facing forward. It is also conceivable to have more or fewer rows of seats facing either direction.

[0087] In the unconventional front-rear seating arrangement shown, in the event of a frontal collision, the forward-facing occupants 60 of the rear row 54 are restrained by their respective seatbelts 56. The rearward-facing occupants 60 of the front row 52 are restrained by the backrests of the vehicle seats 50 during a frontal collision. Therefore, the seats 50 must be configured to support the occupants 60 in the event of a collision. For the forward-facing occupants 60 of the rear row 54, the seatbelts 56 provide a degree of restraint. However, it is desirable that both rows 52 and 54 include additional restraints for head and neck support.

[0088] Since the front row 52 does not need to face forward and is not necessarily adjacent to the dashboard 42 or the area where the dashboard is typically located, there can be a significant amount of space between the front row 52 and the front passenger compartment structure facing forward. Therefore, deploying the airbag from this location may not be effective due to the large volume required. This will cause problems in determining the size of the airbag(s) and inflator(s) to occupy that large volume, and may also cause problems in deploying the airbag(s) to that large volume within the necessary short time required to protect occupants in a collision.

[0089] With this in mind, the airbag 70d is positioned in front of the associated seat 50 in each row 52, ​​54 in the direction the occupants 60 in these seats are facing (i.e., behind the front row 52 and in front of the rear row 54). The airbag 70d extends in the lateral direction of the vehicle 20 and is generally parallel to the width of the seat 50. Alternatively, a single airbag 70d may span the entire width of the passenger compartment 40 to protect all passengers 60 (not shown) in an entire row 52 or 54. Since the airbags in each exemplary configuration described herein are identical for each row arranged in the vehicle 20, for the sake of brevity, the construction and operation of the airbags associated only with the seats 50 in the rear row 54 will be discussed.

[0090] The airbag 70d, after deployment, has a generally elongated rectangular configuration and extends from the upper end 179 to the lower end 181 to define an inflatable volume 183. The upper end 181 is connected to the airbag module 68 and receives inflation fluid from the inflation device 74. The lower end 181 is positioned close to the occupant 60. A middle portion 185 is disposed between the upper end 179 and the lower end 181. A forward-facing receiving surface or portion 191 faces the occupant 60. Conversely, a rearward-facing surface or portion 193 faces away from the occupant 60.

[0091] Airbag 70d is a curtain airbag, which has a smaller thickness compared to a conventional front airbag when measured in the direction of travel of vehicle 20. Airbag 70d may have a similar configuration to side impact curtain airbags, which deploy along the side structure of the vehicle in the event of a side impact and / or vehicle rollover. Curtain airbag 70d extends laterally across the width of vehicle 20 and thus helps protect all occupants 60 in the rear seats 50 of the rear 54.

[0092] Roof tethers 180 support the airbag 70d to prevent movement in response to occupant 60 sinking in. More specifically, the roof tethers 180 replace the reaction surface typically required for a frontal passenger airbag. For this purpose, a pair of roof tethers 180 can be provided for the airbag on the inner and outer sides of the airbag 70d, on opposite sides of the occupant 60. Each roof tether 180 extends from a first end 182 connected to the roof 32 and a second end 184 connected to the lower end 181 of the airbag 70d. The first end 182 of the tether 180 is connected to the vehicle 20 behind the airbag 70d, the occupant 60, and the seat 50 (i.e., in front of the front row 52 and behind the rear row 54). The second end 184 may be configured or include a stress reducer for distributing the connection between the tether 180 and the airbag 70d over a large surface of the airbag fabric to prevent tearing.

[0093] The tether 180 can also help hold the airbag 70d at a desired position or height within the vehicle 20. For example, the tether 180 can position the airbag 70d at a slight angle toward the vehicle seats 50 and occupants 60 (forward in the vehicle 20 for the front seats 52 and rearward in the vehicle 20 for the rear seats 54).

[0094] Advantageously, such as Figure 8 As shown, the position of the first end 182 / roof 32 connection is positioned such that the tether 180 extends in a direction or along a path that approximates or coincides with the path F along which the occupant 60 travels and contacts the receiving portion 191 of the airbag 70d. In this way, the tension applied to the airbag 70d by the tether 180 can be opposite to the impact force applied to the airbag by the trapped occupant 60. As a result, the roof 32 serves as a reaction surface for the airbag 70d via the tether 180. Figures 7 to 8 The exemplary airbag 70d therefore does not need to interact with the vehicle’s front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0095] Figures 9A to 9B Another exemplary configuration of the occupant restraint system 10e is shown. In this configuration, the airbag module 68 includes an airbag 70e and a tether 196. The airbag 70e is a curtain airbag, which has a smaller thickness compared to a conventional front airbag when measured in the direction of travel of the vehicle 20. The airbag 70e may have a similar configuration to side-impact curtain airbags, which deploy along the side structure of the vehicle in the event of a side impact and / or vehicle rollover. The curtain airbag 70e extends laterally across the width of the vehicle 20 and thus helps protect all occupants 60 in the rear seats 50 of the rear 54.

[0096] The airbag 70e, after deployment, has a generally elongated rectangular configuration. The airbag 70e extends from the upper end 186 to the lower end 188 and defines an inflatable volume 189. The upper end 186 connects to the airbag module 68 and includes a narrow top portion 190. Figure 9B It is used to receive the inflation device 74. The middle portion 197 is disposed between the upper end 186 and the lower end 188. The forward-facing receiving surface or portion 201 faces the occupant 60. The opposite rearward-facing surface or portion 203 faces away from the occupant 60.

[0097] like Figure 9B As shown, the widened protective portion 192 extends downward from the top portion 190. The protective portion 192 is configured to receive and assist in the protection of the occupant 60. The lower end portion 188 is positioned close to the occupant 60. Due to this configuration, the space or area occupied by the airbag module 68 in the vehicle 20 can be reduced.

[0098] Reference Figure 9B The airbag 70e may include an internal tether 194 for assisting in shaping or otherwise controlling the inflation configuration. More specifically, the tether 194 may be used to control the thickness of the curtain airbag 70e in the anteroposterior direction and / or create parallel, vertically oriented inflatable chambers 195. As shown, the chambers 195 extend from an upper end 186 to a lower end 188. Such tethers and the resulting chambers may be implemented in any of the exemplary airbag configurations shown and / or described herein, such that the airbag is thicker in certain areas (e.g., those in front of the occupant 60) and thinner in certain areas (e.g., the area between the occupants).

[0099] Roof rope 196 ( Figure 9A The airbag 70e is supported to prevent movement in response to the occupant 60 sinking in. More specifically, roof tethers 196 replace the reaction surface typically required for frontal passenger airbags. For this purpose, a pair of roof tethers 196 can be provided for the airbag on the inner and outer sides of the airbag 70e, on opposite sides of the occupant 60. Each roof tether 196 extends from a first end 198 connected to the roof 32 and a second end 199 connected to the lower end 188 of the airbag 70e. The first end 198 of the roof tether 196 is connected to the vehicle 20 behind the airbag 70e, the occupant 60, and the seat 50. The second end 199 may be configured or include a stress reducer for distributing the connection between the tether 196 and the airbag 70e over a large surface of the airbag fabric to prevent tearing.

[0100] The roof tether 196 can also help hold the airbag 70e at a desired position or height within the vehicle 20. For example, the roof tether 196 can position the airbag 70e at a slight angle toward the vehicle seats 50 and occupants 60 (forward in the vehicle 20 for the front seats 52 and rearward in the vehicle 20 for the rear seats 54). Advantageously, as Figure 9A As shown, the position of the first end 198 / roof 32 connection is positioned such that the roof tether 196 extends in a direction or along a path that approximates or coincides with the path F along which the occupant 60 travels and comes into contact with the receiving portion 201 of the airbag 70e.

[0101] In this way, the tension applied to the airbag 70e by the roof tether 196 can be opposite to the impact force applied to the airbag by the trapped occupant 60. As a result, the roof 32 serves as a reaction surface for the airbag 70e via the tether 196. Figures 9A to 9B The exemplary airbag 70e therefore does not need to interact with the vehicle’s front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0102] Figure 10 Another exemplary configuration of the occupant restraint system 10f is shown. Figure 10 In this configuration, the airbag module 68 includes an airbag 70f, a forming sheet 214, and a roof tether 210. After deployment, the airbag 70f extends from the upper end 200 to the lower end 202 and defines an inflatable volume. A middle portion 205 is disposed between the upper end 200 and the lower end 202.

[0103] Airbag 70f includes a forward-facing receiving surface or portion 206 facing the occupant 60. Conversely, a rearward-facing surface or portion 204 faces away from the occupant 60. Portions 204, 206 are interconnected by connections 210 (e.g., tethers, stitching, fabric welding, adhesives, etc.) to form a plurality of inflatable chambers 212. The chambers 212 may extend laterally across the width of airbag 70f. Airbag 70f may laterally span the entire width of the passenger compartment 40, and thus help protect occupants 60 in an entire row of seats in the vehicle. Alternatively, airbag 70f may laterally span the width of a single passenger seat position, and thus help protect occupants 60 in a single seat (not shown).

[0104] The shaping tab 214 is fastened to opposite sides (e.g., inside and outside) of the airbag 70f to help control the shape of the airbag. In one example, the shaping tab 214 shapes the airbag 70f into a curved configuration when viewed from the side (e.g., convex toward the occupant 60).

[0105] Roof tethers 220 support the airbag 70f to prevent movement in response to occupant 60 sinking in. More specifically, the roof tethers 220 replace the reaction surface typically required for a frontal passenger airbag. For this purpose, a pair of roof tethers 220 can be provided for the airbag on the inner and outer sides of the airbag 70f, on opposite sides of the occupant 60. Each roof tether 220 extends from a first end 222 connected to the roof 32 and a second end 224 connected to the forming piece 214. The first end 222 of the roof tether 220 is connected to the vehicle 20 behind the airbag 70f, occupant 60, and seat 50. The second end 224 is connected to the forming piece 214 in a manner that helps maintain the convex shape of the airbag 70f during deployment.

[0106] The roof tether 220 also helps to hold the airbag 70f in a desired position or height within the vehicle 20. As shown, the roof tether 220 can position the airbag 70f at a slight angle toward the vehicle seat 50 and occupant 60, while the forming piece 214 maintains the convex curvature of the airbag. Advantageously, as Figure 10As shown, the position of the first end 222 / roof 32 connection is positioned such that the roof tether 220 extends in a direction or along a path that approximates or coincides with the path F along which the occupant 60 travels and comes into contact with the receiving portion 206 of the airbag 70f.

[0107] In this way, the tension applied to the airbag 70f by the roof tether 220 can be opposite to the impact force applied to the airbag by the trapped occupant 60. As a result, the roof 32 serves as a reaction surface for the airbag 70f via the tether 220. Figure 10 The exemplary airbag 70f therefore does not need to interact with the vehicle’s front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0108] Figure 11 Another exemplary configuration of the occupant restraint system 10g is shown. Figure 11 The occupant restraint system 10g and Figure 10 The vehicle safety system is exactly the same, except that the forming piece 214 and the tether 220 work together to form the airbag 70g, so that the panel 202 is concave away from the occupant 60.

[0109] Figure 12 Another exemplary configuration of the occupant restraint system 10h is shown. Figure 12 In this configuration, the airbag module 68 includes an airbag 70h and a roof tether 270. After deployment, the airbag 70h extends from the upper end 240 to the lower end 242 and defines an inflatable volume 244. A middle portion 245 is disposed between the upper end 240 and the lower end 242. A forward-facing receiving surface or portion 247 faces the occupant 60. Conversely, a rearward-facing surface or portion 249 faces away from the occupant 60.

[0110] The airbag 70h includes a first portion 246 extending along the roof 32 and a second portion 248 having a U-shaped configuration and connected to the first portion. The first portion 246 is connected to the airbag module 68 and receives inflation fluid from the inflation device 74.

[0111] The second part 248 includes a pair of spaced-apart branches 252, 254 connected by a connecting portion 256. Branch 252 connects to the first part 246. Branch 254 is the free end of the second part 248. Branches 252, 254 terminate near the roof 32. The connecting portion 256 is positioned close to the occupant 60. Branches 252, 254 are particularly hindered from moving toward each other due to pressurized inflation fluid in the branches. This is achieved by preloading branches 252, 254 to prevent them from moving toward each other.

[0112] Compared to a single-chamber construction with the same external perimeter area, the U-shaped airbag 70h has a smaller inflatable volume 244, while using more airbag fabric to define the inflatable volume. Because the branches 252 and 254 of the U-shaped airbag 70h have a relatively small thickness, they have a high surface area to volume ratio. This makes the branches 252 and 254 relatively rigid after inflation.

[0113] Roof tethers 270 support the airbag 70h to prevent it from moving in response to the occupant 60 sinking in. More specifically, the roof tethers 270 replace the reaction surface typically required for a frontal passenger airbag. For this purpose, a pair of roof tethers 270 can be provided for the airbag on the inner and outer sides of the airbag 70h, on opposite sides of the occupant 60. Each roof tether 270 extends from a first end 272 connected to the roof 32 and a second end 274 connected to a branch 252 at the lower end 242 of the airbag 70h. The first end 272 of the roof tether 220 is connected to the vehicle 20 behind the airbag 70h, the occupant 60, and the seat 50.

[0114] The airbag 70h is constructed such that during inflation, branches 252 and 254 tend to move away from each other. Since branch 254 is free, the occupant 60 getting caught in branch 254 causes branch 254 to move along path F toward branch 252. Advantageously, as... Figure 12 As shown, the position of the first end 272 / roof 32 connection is positioned such that the roof tether 270 extends in a direction or along a path that approximates or coincides with the path F along which the occupant 60 travels and comes into contact with the receiving portion 247 of the airbag 70h.

[0115] In this way, the tension applied to branch 252 by the roof tether 270 can be opposite to the impact force applied to airbag 70h by the trapped occupant 60. More specifically, the roof 32 restrains the movement of branch 252 by the tether 270 so that branch 252 can limit the movement of branch 254 along path F. Figure 12 The exemplary airbag 70h configuration therefore does not require interaction with the vehicle's front structure (such as the dashboard, steering wheel, or seats) to provide a reaction surface for the airbag.

[0116] Based on the above, what will be understood is... Figures 1 to 12The exemplary configuration shows that the airbag is configured to utilize the vehicle roof as a reaction surface in both conventional and unconventional seating arrangements. As for "reaction surface," it means the vehicle roof that supports the airbag to prevent movement in response to an impacted occupant. In other words, the airbag attempts to move in a first direction, and the roof exerts a reaction force on the airbag in the opposite (or substantially opposite) second direction to limit / prevent movement of the airbag in the first direction. This allows the airbag to absorb the impact force of the occupant and provide the desired cushioning effect.

[0117] Advantageously, the exemplary configuration may require only the vehicle roof to provide the reaction surface and can provide effective occupant protection without any support from structures present in front of the occupants. The vehicle roof can fully support the airbag module and airbag. In certain exemplary configurations, certain additional structures, such as the windshield (see [link to relevant documentation]), [are used for other purposes]. Figure 4 and Figure 5 ) or vehicle side structure (see Figure 6A and 6B It can also help provide a reaction surface. However, in all of these exemplary configurations, the vehicle structure to which the non-occupant-facing surface of the airbag faces is not used as a reaction surface.

[0118] It will also be understood that features shown and illustrated in any example can be similarly added to or interchanged with features in any other example. Additionally, it will be understood that any of the tethers 120, 168, 174, 180, 196, 220, 270 can be connected to the airbag module, not to the roof 72, side structure, etc. of the vehicle 20. Furthermore, any vehicle safety system shown and described herein can be configured without external tethers connecting the airbag to the vehicle (e.g., any of the tethers 120, 168, 174, 180, 196, 220, 270 can be omitted). In such configurations, the lower end of the airbag is specifically configured to engage the thigh / lower torso of the occupant(s) intended to be protected. Thus, in these configurations, the occupant's thigh / lower torso exerts a reaction force on the airbag and thus holds the lower end of the deployed airbag in place to prevent movement of the lower end of the airbag during occupant entrapment. The occupants can therefore also be used as a reaction surface for the airbag.

[0119] With this in mind, it will be understood that in each exemplary airbag shown and described herein, the rearward-facing surface / parts facing away from the occupant or the middle portion of the airbag does not rely on or engage with vehicle structures (e.g., roof, dashboard, windshield, or seat backs) to limit the movement of the airbag away from the trapped occupant. This helps ensure that the airbags described herein can operate without the presence of vehicle structures omitted in autonomous vehicles (e.g., seat backs, dashboards, etc. in front of the occupant).

[0120] The examples described above are examples of the invention. It is certainly impossible to describe every conceivable combination of components or methods for the purposes of describing the invention, but those skilled in the art will recognize that many other combinations and substitutions of the invention are possible. Therefore, the invention is intended to cover all such changes, modifications, and variations that fall within the spirit and scope of the appended claims.

Claims

1. A restraint system for helping to protect occupants of a vehicle, the vehicle having a roof and a passenger compartment having seats for the occupants, the restraint system comprising: An airbag, which is mounted on the roof of the vehicle, has a stored state and can be inflated to a deployed state, and when deployed, the airbag has a forward-facing occupant receiving portion and a rearward-facing portion facing away from the occupant. The airbag has one or more connection points to the roof of the vehicle; and The airbag and the connecting portion are configured such that the vehicle roof serves as a reaction surface to support the airbag from movement in response to an occupant impacting the occupant receiving portion during forward movement, and the system is independent of the rearward-facing portion of the airbag engaging the vehicle structure and uses the vehicle structure as a reaction surface to support the airbag from movement in response to an occupant impacting the occupant receiving portion during forward movement, and wherein the airbag includes a first portion and a U-shaped second portion, the first portion extending along the vehicle roof, the second portion extending toward the occupant and having a first branch extending from the first portion and a second branch connected to the first branch, wherein the second branch moves to engage with the first branch in response to an occupant sinking in.

2. The restraint system of claim 1, further comprising at least one tether connected to the first branch and the roof, the at least one tether for restricting movement of the first branch in response to engagement of the second branch with the first branch.

3. The constraint system according to claim 2, wherein, The airbag is configured to be positioned in front of the vehicle occupants, and the second end of the tether is configured to be connected to the vehicle roof behind the vehicle occupants.

4. The constraint system according to claim 2, wherein, The airbag is configured to pivot about the connection between the airbag and the vehicle roof in response to the action of an occupant during an impact, and wherein the upper portion of the airbag is configured to engage the vehicle roof such that the vehicle roof serves as a reaction surface for restraining the airbag from moving in response to an occupant sinking in.

5. The constraint system according to claim 1, wherein, The airbag includes at least one internal tether for shaping the receiving portion.

6. The constraint system according to claim 5, wherein, The at least one internal tether helps reduce the surface tension on the fabric of the receiving portion.

7. The constraint system according to claim 1, wherein, The restraint system is configured to use only the roof as the reaction surface.

8. The restraint system according to claim 1, further comprising: A sensor for sensing the occurrence of an event in which the airbag is expected to deploy and for generating a signal indicating the occurrence of the event; as well as A controller is connected to the sensor and, in response to receiving the signal, actuates an inflation device to inflate the airbag to the deployed state.

9. A restraint system for helping to protect occupants of a vehicle, the vehicle having a roof and a passenger compartment having seats for the occupants, the restraint system comprising: An airbag is mounted on the roof of the vehicle. The airbag has a stored state and can be inflated to a deployed state. When deployed, the airbag has a first end, a second end, and an intermediate portion connected to the roof. The airbag is connected to the roof such that the roof serves as a reaction surface to support the airbag and prevent it from moving in response to an occupant sinking into the airbag during forward movement. The middle portion does not engage with the vehicle structure in response to an occupant sinking into the airbag. The airbag includes a first portion and a U-shaped second portion. The first portion extends along the vehicle roof, and the second portion extends toward the occupant and has a first branch extending from the first portion and a second branch connected to the first branch. The second branch moves to engage with the first branch in response to an occupant sinking into the airbag.

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