Abstract:
The present invention relates to an airbag assembly comprising: a folded airbag adapted to be inflated and deployed into a passenger compartment upon detection of a collision, a chute for guiding the airbag when it is inflated, the chute extending between the folded airbag and a deployment opening, wherein the chute widens into a side direction.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to the field of airbag safety systems, and more particularly to an airbag assembly. 
   Airbag safety systems have come into widespread use in automotive vehicles and trucks. For example, a modern car can have various airbags, such as a driver airbag, passenger airbag, knee airbags, side airbags and/or other airbags. 
   Such airbag systems comprise an inflatable cushion, commonly referred to as an ‘airbag’ which is stored folded in a storage receptacle and then very rapidly inflated, as with gas from a pyrotechnic gas generator, when a collision of the vehicle is detected by sensors. The airbag is thereby deployed in a position to absorb the impact of the driver or a passenger. 
   One or more airbag deployment doors normally overlie the airbag receptacle and are forced open when the airbag is inflated to allow deployment of the airbag through the opening created by the door panel movement. 
   It is critical that the airbag deploys within milliseconds of activation of the airbag system in order to protect the occupant. However, the inflating airbag can exercise a considerable force onto the occupant. This causes a concern for child safety when the airbag deploys into a forward facing child safety seat. In such instances, the airbag may cause considerable harm or even death to the front facing child. 
   To prevent such harm some prior art airbag safety systems have an airbag deactivation switch. By means of the airbag deactivation switch the airbag safety system can be switched off in order to prevent deployment of the airbag when a collision is detected. This allows placing a child in front of an airbag. However, there is still a residual risk in case the driver has inadvertently forgotten to switch off the airbag system when the child is placed in front of the airbag. Another risk of such systems is that the airbag needs to be reactivated when an adult is placed in front of the airbag which may also be forgotten by the driver. 
   U.S. Pat. No. 6,846,012 shows a child seat sensor assembly. Upon sensing the presence of a child seat, a control signal is sent to the vehicle control system in order to limit or prevent deployment of the airbag. However, this system requires a special child safety seat. 
   The invention aims to provide an improved airbag assembly that reduces the maximum force impaled to an occupant in order to reduce the risk of injury, especially when the occupant is a child. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention there is provided an airbag assembly comprising a folded airbag adapted to be inflated and deployed into a passenger compartment upon detection of a collision, a chute for guiding the airbag when it is inflated, the chute extending between the folded airbag and a deployment opening, wherein the chute widens into a side direction. 
   The widening of the chute into a side direction has the effect that the airbag is filled out at its sides ahead of its middle region when it is deployed into the passenger compartment. By pushing the airbag to an outer area, the maximum force onto an occupant located directly in front of the airbag is reduced, thus reducing the risk of injury. The reduction of the maximum force allows placing a child in front of the airbag. 
   In accordance with an embodiment of the invention the chute has at least one sloped sidewall. For example, the chute has a top wall, a bottom wall and left and right sidewalls. In this instance at least the left or the right sidewall is sloped. For example, both the left and the right sidewalls are sloped with the same or a different slope angle. In addition the top and/or bottom sidewalls can also be sloped with the same or a different slope angle than the left and/or right sidewalls. 
   In accordance with an embodiment of the invention the sloped angle of the at least one sloped sidewall is between 20° and 70°. Preferably the slope angle is approximately 45°. 
   The at least one sloped sidewall has the effect that the gas flow streaming into the airbag when it is deployed into the passenger compartment is directed such that the sides of the airbag are filled out ahead of the middle region of the airbag. 
   In accordance with a preferred embodiment of the invention, the sloped sidewalls of the chute form a V-shape. 
   In accordance with an embodiment of the invention at least one of the sloped sidewalls of the chute has a convex surface or a concave surface. 
   In accordance with an embodiment of the invention the chute is funnel-shaped. 
   The present invention can be used for various kinds of airbags, such as driver airbags, passenger airbags, knee airbags, side airbags and other airbag safety systems. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following preferred embodiments of the invention will be explained in greater detail by way of example only making reference to the drawings in which: 
       FIG. 1  shows a side view of an automotive vehicle, 
       FIG. 2  shows a schematic cross-sectional view of a first embodiment of an airbag assembly of the invention, 
       FIG. 3  shows a schematic side view of an instrument panel having a second embodiment of an airbag assembly of the invention, 
       FIG. 4  shows a perspective view of a third embodiment of an airbag chute of the invention, 
       FIG. 5  shows a perspective view of a fourth embodiment of an airbag chute of the invention, 
       FIG. 6  shows a perspective view of a fifth embodiment of a chute of the invention, 
       FIG. 7  shows a schematic cross-sectional view of a sixth embodiment of an airbag assembly of the invention during deployment of the airbag into a passenger compartment, 
       FIG. 8A  shows a schematic view of an instrument panel having a further embodiment of an airbag assembly of the invention in which the airbag assembly is in a lower portion of the vehicle for a knee airbag application, and 
       FIG. 8B  shows a schematic view of an instrument panel having a further embodiment of an airbag assembly of the invention in which the airbag assembly is in the door of the vehicle for a side airbag application and/or a knee airbag application. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a side view of an automotive vehicle  100 . The automotive vehicle  100  defines a coordinate system, i.e. a forward or x-direction, a side or y-direction and a vertical or z-direction as shown in the coordinate system depicted in  FIG. 1 . This coordinate system is referenced throughout the following  FIGS. 2 to 7 . Like reference numerals are used to designate like parts in the Figs. 
     FIG. 2  shows a schematic cross-sectional view of an airbag assembly  202  that can be mounted in automotive vehicle  100  (cf.  FIG. 1 ). The airbag assembly  202  can be a passenger airbag, a knee airbag, a side airbag or another kind of airbag assembly. 
   For the purpose of ease of explanation it is assumed in the following that the airbag assembly  202  is a passenger airbag assembly. 
   A folded passenger airbag  204  is arranged below an instrument panel  206  in the interior of the automotive vehicle. The airbag assembly  202  operates by deploying the passenger airbag  204  which expands towards the instrument panel  206  and is guided in chute  208 . The deploying airbag encounters airbag deployment door  210  and forces the airbag deployment door  210  to separate from the instrument panel  206  and open. In order for the airbag deployment door  210  to open, a weakening line, such as a groove or a perforation can be provided, such as along a portion of the perimeter of the airbag deployment door  210  as it is as such known from U.S. Pat. No. 5,744,776. 
   The chute  208  has (viewed into the x-direction) a left sidewall  212  and a right sidewall  214 . The left sidewall  212  encloses an angle  216  with the x-direction and the right sidewall  214  encloses an angle  218  with the x-direction. Preferably both angles  216  and  218  are within the range between 20° to 70°. For example, both angles  216  and  218  are approximately 45°. 
     FIG. 3  schematically shows an instrument panel  320  that is arranged below windshield  322  of automotive vehicle  100  (cf.  FIG. 1 ). The instrument panel  320  has an opening  324  on the driver&#39;s side for the installation of an instrument cluster (not shown) and an airbag deployment door (not shown) of desired shape, in this case rectangular, on the passenger&#39;s side whose entire or partial perimeter is defined by a tear seam moulded or cut into the underside of the instrument panel. The tear seam is preferably invisible to the occupants of the vehicle for reasons of aesthetics. 
   The airbag deployment door covers an airbag deployment opening  326 . An airbag chute  308  is arranged below the airbag deployment opening  326 . The airbag chute  308  serves to guide an airbag when it is inflated upon detection of a collision. In other words the chute  308  transitions the space between the canister where the folded airbag is stored and the back of the airbag deployment door that covers the airbag deployment opening  326  in order to guide the deployment of the inflating airbag. When the inflating airbag hits the back of the airbag deployment door, the airbag deployment door opens and the inflating airbag deploys into the passenger compartment. 
   Due to the sloped left and right sidewalls  312 ,  314  of the chute  308  that widen the chute into the y-direction the sides of the airbag are filled out ahead of the middle region of the airbag when the inflating airbag travels along the chute  308  and deploys into the passenger compartment. In addition the upper wall  328  and the lower wall  330  of the chute  308  are also sloped in the embodiment considered here. Hence, in this embodiment the chute  308  has a V-shape both in the horizontal plane and the vertical plane. 
     FIGS. 4 ,  5  and  6  show various embodiments of chutes of the invention that are funnel-shaped. In the embodiment of  FIG. 4  the funnel-shape of the chute  408  is constituted by a number of six sloped walls  432  whereas the chute  508  has a number of ten sloped walls  532 . In the embodiment of  FIG. 6  the chute  608  has a conical form constituted by a single wall  632 . 
   It is to be noted that a common feature of the funnel-shaped chutes  408 ,  508  and  608  of  FIGS. 4 ,  5  and  6 , respectively, is that the chutes widen into a side direction relative to the passenger that is to be positioned in front of the airbag deployment opening. 
     FIG. 7  shows an alternative embodiment of a passenger airbag assembly  702  of the invention. The passenger  734  is placed on the passenger seat in front of the airbag deployment opening that is covered by airbag deployment door  736 . The chute  708  has sloped sidewalls  712  and  714 ; a folded passenger airbag  704  is located at the rear opening of the chute  708 . When a collision is detected the passenger airbag is inflated and expands along the chute  708 . 
   When the inflating passenger airbag  704  hits the airbag deployment door, the airbag deployment door  736  opens such that the passenger airbag  704  can penetrate into the passenger compartment. The dashed lines in  FIG. 7  show the contour of passenger airbag  704  during its deployment into the passenger compartment towards the passenger  734 . Due to the sloped sidewalls  712  and  714  of the chute  708  the side portions  738 ,  740  of the passenger airbag  704  are filled with a higher gas pressure than the middle region  742  of the passenger airbag  704 . The direction of the expansion of the side portion  738  of the passenger airbag is indicated by arrow  746  whereas the direction of the expansion of the side portion  740  is indicated by the arrow  744 . The direction of the expansion of the middle region  742  is indicated by arrow  748 . 
   Due to the sloped sidewalls  712  and  714  the pressure built-up in the side portions  738  and  740  is more abrupt than in the middle region  742 . Therefore the force with which the middle region  742  eventually hits the passenger  734  is reduced. This reduces the risk of injury of the passenger  734  and it also facilitates to place a child in front of the passenger airbag assembly  702 . 
   The sidewall  712  and/or the sidewall  714  can have a convexe or concave shape. The doted lines in  FIG. 7  show a convexe sidewall  712 ′ and a concave sidewall  712 ″ as alternatives to straight sidewall  712 . 
   The chute  708  can be attached to an airbag deployment door cover, airbag module or to the instrument panel  720 . The chute  708  can be designed as a separate part or integral to the airbag module, instrument panel or instrument panel structure. 
     FIG. 8A  shows a schematic view of an instrument panel  320  having a further embodiment of the present invention that provides a knee airbag. An airbag assembly  826 B (similar to the assembly  202  discussed above) is located in a lower portion  321  of the vehicle for knee airbag functionality.  FIG. 8B  shows a schematic view of a door of a vehicle having a further embodiment of the present invention that provides a side airbag and/or a knee airbag. An airbag assembly  826 C and/or  826 D (similar to the assembly  202  discussed above) may be located in the door for side airbag functionality. Airbag assembly  826 D may also operate as a knee airbag depending on location. 
   It is to be noted that the present invention is broadly applicable to various airbag designs with or without an inner door. It can be applied to either seamless or discrete airbag deployment doors. The location of the airbag assembly can be on the upper passenger side as well as the lower driver or passenger sides. 
   LIST OF REFERENCE NUMERALS 
   
       
       
         
             100  Automotive vehicle 
             202  Airbag assembly 
             204  Passenger airbag 
             206  Instrument panel 
             208  Chute 
             210  Airbag deployment door 
             212  Left sidewall 
             214  Right sidewall 
             216  Angle 
             218  Angle 
             308  Chute 
             312  Left sidewall 
             314  Right sidewall 
             320  Instrument panel 
             322  Windshield 
             324  Opening 
             326  Airbag deployment opening 
             328  Upper wall 
             330  Lower wall 
             408  Chute 
             432  Wall 
             508  Chute 
             532  Wall 
             608  Chute 
             632  Wall 
             702  Passenger airbag assembly 
             704  Passenger airbag 
             708  Chute 
             712  Sidewall 
             714  Sidewall 
             720  Instrument panel 
             734  Passenger 
             736  Airbag deployment door 
             738  Side portion 
             740  Side portion 
             742  Middle region 
             744  Arrow 
             746  Arrow 
             748  Arrow