Abstract:
A chute for receipt of a deploying air bag includes a compartment having first and second sidewalls extending laterally outwardly from a rear bag receiving aperture toward a front cover panel. The expanding volume of the chute enables a deploying air bag to outwardly expand at least partially parallel to a frangible seam in the front cover panel before the bag contacts the seam and ruptures it. As a result, the force of the bag is dispersed evenly along the seam to reduce maximum bag force exerted against the portion of the front cover panel located directly in front, or in the center, of the bag.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to vehicle safety systems employing air bags and more particularly to an air bag chute for an air bag.  
       BACKGROUND OF THE INVENTION  
       [0002]     In known air bag deployment arrangements, deployable outer doors of an air bag housing are separated by at least one tearable seam, against which a deploying air bag exerts a force when the bag is inflating. The expanding bag exerts force only on a portion of the seam centrally located with respect to the bag&#39;s leading surface.  
         [0003]     There is a need for an air bag deployment arrangement which will allow the air bag to exert pressure substantially evenly along the entire extent of the tearable seam, thereby reducing maximum force from being exerted only against a portion of the air bag door located centrally in front of the deploying air bag.  
       SUMMARY OF THE INVENTION  
       [0004]     An air bag chute has a compartment having a front cover panel including at least one frangible seam therein, a rear aperture opposite the front cover panel adapted to receive a deploying air bag, and first and second walls extending between the rear aperture and the front cover panel, at least one of the walls extending laterally outwardly from the rear aperture towards the front cover panel, whereby the compartment is adapted to enable a deploying air bag to expand at least partially parallel to the frangible seam before contacting the front cover panel.  
         [0005]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0007]      FIG. 1  is a perspective view of a vehicle with an instrument panel including an air bag safety system employing an air bag chute with an air bag according to the principles of the present invention;  
         [0008]      FIG. 2  is cross sectional view of the air bag safety system of  FIG. 1  taken along line  2 - 2  of  FIG. 1 ;  
         [0009]      FIG. 2A  is a detailed cross sectional view of the air bag safety system of  FIG. 1 ;  
         [0010]      FIG. 3  is a rear view of the air bag safety system of  FIG. 1 ;  
         [0011]      FIG. 4A  is an environmental view of the air bag safety system of  FIG. 1  during the expansion of the air bag; and  
         [0012]      FIG. 4B  is top view of an occupant contacting the air bag after the air bag has fully expanded from the air bag safety system of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0013]     The following description is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0014]     The present invention is generally related to an air bag chute for use with a safety system disposed in a motor vehicle. Although the following exemplary description refers to the use of an air bag chute disposed in an instrument panel of a motor vehicle, it will be understood that the present invention may be applicable to other types of air bag safety systems, and to different locations within the vehicle. Further, the foregoing description is understood to not limit the appended claims.  
         [0015]     With reference to  FIG. 1 , a motor vehicle  8  including a passenger area  10  is shown. The passenger area  10  includes an instrument panel  12  which is adapted to receive an air bag system  14 . In particular, with continuing reference to  FIG. 1 , and additional reference to  FIGS. 2, 2A  and  3 , the instrument panel  12  includes an aperture  16  for receipt of the air bag system  14 . The air bag system  14  includes an air bag chute cover panel  18  coupled to an air bag chute  20 .  
         [0016]     Panel  18  includes an outer surface  22  facing passenger area  10 , an interior surface  24  and at least one frangible or tearable seam  26 . Panel  18  may be formed of any appropriate polymeric material, such as thermoplastic polyolefin (TPO), and may be formed in any shape as desired to coordinate with the instrument panel  12  and the passenger area  10 . Cover panel  18  may alternatively include a molded in air vent  28  (shown in phantom) operable to be coupled with the heating and cooling system (not shown) of the motor vehicle  8 , to provide the passenger area  10  with pre-heated or cooled air.  
         [0017]     Interior surface  24  of panel  18  may include at least one molded feature  30 , such as molded protrusions, operable to couple the air bag chute  20  to panel  18 . Additionally, it will be understood that any appropriate coupling mechanism could be used to fasten interior surface  24  to the air bag chute  20  such as, for example, adhesives, mechanical fasteners, or in the alternative, the instrument panel interface  18  could be integrally formed with air bag chute  20 .  
         [0018]     In addition, interior surface  24  may define a plurality of flanges  32  operable to couple panel  18  to a surface of vehicle  8 . Further, the second surface  24  may include projections  34  to couple the second surface  24  to the instrument panel  12 . It should be noted, however, that any appropriate mechanism could be employed to couple the second surface  24  to the instrument panel  12  and motor vehicle  8 .  
         [0019]     The at least one seam  26  may be generally formed along the centerline C of panel  18 , however, the seam  26  may be formed at any desirable location on panel  18 , or in the alternative, the seam  26  may include additional horizontal and vertical elements (not shown). The seam  26  further serves to divide panel  18  into two doors  29 , however, depending on the seam  26 , the doors  29  may be in various shapes and quantities. The seam  26  is generally integrally formed with panel  18 , and typically seam  26  is formed by molding a pre-selected area of panel  18  with a reduced thickness T 1  as compared to a thickness T 2  of panel  18  (as best shown in  FIG. 2A ). Thus, the reduced thickness T 1  enables the seam  26  to fracture to enable an air bag B (as shown in  FIG. 4A ) to enter the passenger area  10  via chute  20  as will be described in greater detail below.  
         [0020]     The air bag chute  20  includes at least one door  36  coupled to a compartment  38 , in turn coupled to an air bag module  40 . A flange  42  ( FIG. 3 ) couples air bag chute  20  to interior surface  24  of panel  18 . The at least one door  36  (two doors  36  shown) may be integrally formed with the compartment  38  or may, in the alternative, be integrally formed with panel  18 .  
         [0021]     The number of doors  36  is determined by the configuration of seam  26  of panel  18 , in particular, seam  26  serves to separate the instrument panel interface  18  into the two doors  29  which correspond to the doors  36 . The doors  36  are generally spaced apart along the centerline C of panel  18  to enable the air bag B to expand into the passenger area  10  after it has initially expanded into compartment  38 , as will be discussed in greater detail below. The doors  36  further include at least one aperture  44  for receipt of a protrusion  30  extending from inner surface  24  to couple doors  36  to inner surface  24  of panel  18 . However any appropriate alternative technique could be used to couple doors  36  to panel  18 . Doors  36  may be integrally formed about their outer periphery with compartment  38  and may include at least one flex rib  46 , thereby enabling doors  36  to flex outwardly to enable air bag B to expand into passenger area  10 .  
         [0022]     The compartment  38  includes top and bottom walls  48  and  49 , respectively, coupled together via end walls  50  and  51 . Compartment  38  is formed such that end walls  50  and  51  diverge outwardly from each other as they extend from a rear aperture defined by rear edge  68  to front  66  of compartment  38 . One suitable configuration has a top view cross section of compartment  38  forming an isosceles trapezoid as shown in  FIG. 2 . The top and bottom  48 ,  49 , of compartment  38  are generally parallel to each other and approximately perpendicular to the end walls  50 ,  51 . Generally, the base angle A at which end walls  50 ,  51  diverge from rear side  68  can be between 91 and 180 degrees, but is more preferably within 95-128 degrees.  
         [0023]     Base angle A of compartment  38  enables air bag B to enter the chute via the rear aperture and then preliminarily expand at least partially parallel to seam  26  within compartment  38  to a greater surface area prior to exiting panel  18 . Specifically, the greater the base angle A, the greater the area for the air bag B to expand, and this increase in surface area serves to more evenly distribute the force of the air bag B along seam  26  as it exits compartment  38  at panel  18 , while increasing a region in the passenger area  10  which is protected by the air bag B (as best shown in  FIG. 4A ). Thus, the base angle A can be tuned to any desired angle, depending upon the vehicle, to increase the surface area of coverage and evenly distribute the force of the air bag B on deployment. Base angle A may be different at each end wall  50 ,  51  in order to direct the air bag B into a desired expansion path for a given vehicle application.  
         [0024]     A distance D separates doors  36  and generally corresponds with thickness T 1  of seam  26  in panel  18 .  
         [0025]     As the air bag deploys, it will spread throughout the compartment  38 , and apply a substantially uniform force against seam  26 . The force will cause the doors  36  to flex outwardly, and simultaneously cause seam  26  to rupture, as shown in  FIG. 4A . Once seam  26  fractures, doors  29  of panel  18  will flex outwardly to enable air bag B to expand into passenger area  10  and surround a passenger  100 , as illustrated in  FIG. 4B .  
         [0026]     Base angle A formed in compartment  38  of air bag chute  20  provides air bag B with a greater surface area within which to preliminarily expand in compartment  38  and also serves to more evenly distribute the force of the air bag B over a greater surface area. This even distribution of the expansion force reduces the force of air bag B as it exits compartment  38 , thereby protecting passengers which may be seated close to panel  18 .  
         [0027]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.