Abstract:
A cross beam assembly extends between side frame members of a vehicle and includes a beam having a hollow interior. The beam defines an opening formed therein. The assembly further includes an air bag inflator assembly having a source of pressurized gas for expelling gas to inflate an air bag. The inflator assembly is disposed within the hollow interior of the beam such that activation of the inflator assembly expels gas through said opening.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to motor vehicles, and in particular to vehicles having a structurally rigid cross car beam. 
     A conventional motor vehicle has an engine compartment towards its forward end and a passenger compartment rearward of the engine compartment. A laterally extending partition, commonly referred to as a bulkhead or firewall, is disposed between the engine compartment and the passenger compartment. Most passenger vehicles include an instrument panel positioned rearward of the firewall. The instrument panel is generally positioned underneath the windshield and attached to the frame of the vehicle rearward of the engine compartment. For example, the lateral ends of the instrument panel may be attached to the cowl sides of the frame of the vehicle. The instrument panel encloses various vehicle components, such as electrical and ventilation systems, audio systems, vehicle instrument gauges and displays, auxiliary compartments, and inflatable air bag modules. 
     It is becoming customary in modern vehicles to include a structural cross car beam extending the lateral length of the vehicle between the cowl sides. Opposing ends of the cross car beam are attached to frame members of the vehicle. A conventional cross car beam is a closed steel chamber that increases the structural integrity of the vehicle, offering resistance to impact sustained along the sides of the vehicle. The cross car beam is often positioned adjacent to or within the instrument panel. The cross car beam may support various vehicle components, such as glove compartments, audio/video players, steering column bracket, energy absorbing brackets, wiring harnesses, and air ventilation ducts. 
     Conventional cross car beams have a generally constant diameter or cross-sectional area extending substantially across its entire width to provide a sufficiently strong beam. To incorporate the cross car beam into the vehicle at its desired position, i.e., rearward of the firewall and below the windshield, the cross car beam often intrudes into the instrument panel and may therefore be incorporated therewith. In some vehicles, the cross car beam is preinstalled into the instrument as a modular assembly. The cross car beam and the instrument panel are then simultaneously attached to the vehicle. Because of the position of the cross car beam relative to the instrument panel, it is often difficult to accommodate the mounting space required for the various components installed in the instrument panel. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention relates to a cross beam assembly for a vehicle. The cross beam assembly extends between side frame members of a vehicle and includes a beam having a hollow interior. The beam defines an opening formed therein. The assembly further includes an air bag inflator assembly having a source of pressurized gas for expelling gas to inflate an air bag. The inflator assembly is disposed within the hollow interior of the beam such that activation of the inflator assembly expels gas through said opening. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an instrument panel and first embodiment of a cross car beam assembly in accordance with the present invention. 
         FIG. 2  is a sectional view of the cross car beam assembly taken along lines  2 — 2  of  FIG. 1 . 
         FIG. 3  is a schematic cross sectional view of an embodiment of an air bag inflator assembly which may be used with the cross car beam assembly. 
         FIG. 4  is cross sectional view of a second embodiment of a cross car beam assembly in accordance with the present invention. 
         FIG. 5  is a sectional view of the cross car beam assembly taken along lines  4 — 4  of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, there is illustrated in  FIG. 1 , an instrument panel  10  and a cross car beam assembly, indicated generally at  12  in accordance with the present invention. As will be discussed in detail below, the cross car beam assembly  12  includes an air bag inflator assembly  14  integrally mounted with cross car beam  16  of the assembly  12 . This arrangement provides increased space in the instrument panel for other components, and may also help reduce the weight and cost of the instrument panel  10  and/or cross car beam assembly  12 . This arrangement may also permit shorter depth instrument panels. 
     The instrument panel  12  is generally positioned underneath the windshield of the vehicle and rearward of the vehicle firewall. The instrument panel  10  generally extends along the entire width of the interior of the passenger compartment of the vehicle. The instrument panel  10  can be attached to the vehicle frame by any suitable manner. For example, the ends and rear portion of the instrument panel  10  can be directly attached to portions of the vehicle frame. The instrument panel  10  can have any desired shape and can house various components, such as electrical and ventilation systems, audio systems, vehicle instrument gauges and displays, and auxiliary compartments. 
     The cross car beam assembly  12  generally includes the elongated hollow beam  16  and the air bag inflator assembly  14 . The beam  16  preferably extends laterally across the interior of the passenger compartment. The ends of the beam  16  can be attached to the vehicle frame, such as at the cowl sides. Alternatively, the beam  16  can be attached to the instrument panel  10 . The beam  16  is preferably made of a structurally rigid material, such as steel, that increases the structural integrity of the vehicle by offering resistance to impact sustained along the sides of the vehicle. The beam  16  helps prevent the sides of the vehicle from intruding into the interior of the passenger compartment. 
     In a preferred embodiment, the beam  16  has a generally constant cross-sectional shape along its length to minimize bending and/or collapsing upon itself. However, it should be understood that the beam  16  is not limited to having a constant cross-sectional about its length, and may be formed with slight bends and/or having differing cross-sectional widths and diameters. The beam  16  may also have any suitable cross-sectional shape, such as circular, rectangular, or any unsymmetrical shape. The beam  16  may be formed from a single structure, such as a hollow tube, or may alternatively be formed by attachment of two or more structures. For example, as shown in  FIG. 2 , the beam  16  is formed by a stamped part  19  having a generally hat-shaped cross-sectional shape defining an open end  20 . A generally flat plate  22  is attached to the open end  20  of the part  19 . The part  19  and plate  22  form a closed loop generally rectangular cross-sectional shape. A closed loop cross-sectional shape is preferred due to its generally rigid nature for resisting a bending force. The plate  22  has one or more openings  24  formed therein, the reason for which will be explained below. The openings generally extend in a radial direction relative to an axis defined by the length of the beam  16 . 
     In the embodiment of the cross car beam assembly  12  illustrated in  FIG. 2 , a separate inflator  26  is disposed within the interior  27  of the hollow beam  16 . The inflator  26  can be mounted in the beam  16  by any suitable manner, such as by threaded fasteners  30 . The inflator  26  can be any conventional air bag inflator mechanism capable of generating gases from a source of pressurized gas, such as for example, a solid propellant. The expelled gases are directed into a conventional air bag  32  for proper inflation of the air bag during an impact condition, such as a collision. The inflating air bag  32  helps protect the occupant of the passenger seat positioned rearward of the air bag inflator assembly  14 . An example of a suitable inflator  26  is shown in  FIG. 3 . 
     The inflator  26  includes a separate canister including a cylindrical outer housing  36  having one or more apertures  38  formed therein. An inner sleeve  40  is disposed in the outer housing  36  and also includes one of more apertures  42 . If desired, a rupture disk may be inserted in the apertures  42  which helps prevent contaminants from entering the interior of the sleeve  40 . The inflator  26  preferably includes one or more propellant cartridges or chambers  44  and  46  which house propellant therein. The cartridges or chambers  44  and  46  may contain an explosive charge which excites the propellant, such as ammonium nitrate pellets which generally store pressurized gas in solid form until excited. It should be understood that any suitable conventional air bag propellant may be used. The inflator  26  includes initiators  48  which are electrically connected to a controller (not shown) for actuation and energizing of the inflator  26 . Note that the beam  16  may include apertures (not shown) to provide a pathway for wiring electrically connecting the initiators  48  to the controller. 
     Commonly, the desired position of the beam  16  is positioned at a spaced apart relationship relative to the outer surface of the instrument panel facing the interior of the passenger compartment. Thus, the folded air bag  32  is spaced rearwardly from the inflator  26 , such as by a distance D shown in  FIG. 2 . It is generally desirable to position the folded air bag  32  close to the outer surface of the instrument panel to provide proper deployment of the air bag  32 . To direct the expelled gas from the inflator  26  to the air bag  32 , an optional chute  50  is provided. The chute  50  can be mounted to the beam  16  and/or a portion of the instrument panel  10 . Preferably, the folded air bag  32  is housed in the chute  50 . As shown in  FIG. 2 , the air bag  32  includes an open end  52  facing forward towards the openings  24  of the beam  16 . The open end  52  of the air bag  32  can be sealingly attached to the interior walls  51  of the chute  50 . In the embodiment illustrated in  FIG. 2 , an air bag door  56  is integrally formed with the chute  50 . The door  56  is attached to the instrument panel  10  via a hinge  57  or a tether (not shown). The door  56  covers the air bag  32  when in its non-deployed state. The door  56  is movable to a deployed position, indicated generally by broken lines  58  upon expansion of the air bag  32 . The door  56  can be integrated into the chute  50  as shown in  FIG. 2 . Preferably, the door  56  is attached to the chute  50  by thin walled members  55  which break open to separate a portion of or the entire door  56  from the chute  50  upon deployment of the air bag  32 . Alternatively, the door  56  can be integrally formed in the instrument panel  12  such as by a conventional break-away seam, as is commonly known in the art. 
     Upon detection of an impact condition in which the air bag  32  is to be deployed, a controller energizes one or both of the initiators  48 , which in turn energizes the propellant within the respective chamber  44  and  46 . Energizing of the propellant causes an expansion of gas within the interior of the sleeve  40  which is forced outwardly through the apertures  42  and the apertures  38  of the outer housing  36 . As shown in  FIG. 2 , the expanding gas is directed into the interior  27  of the beam  16  and through the openings  24  into the interior of the chute  50 . The expanding gases can be directed from the interior  27  of the beam  16  to the chute  50  by any suitable manner. Preferably, at least the ends of the beam  16  are capped so that the expanding gases are directed through the openings  24 . More preferably, the interior  27  of the beam  16  is closed off adjacent the inflator  26  so that the inflator  26  is disposed in a generally small chamber within the interior of the beam  16 . Alternatively, additional chutes or conduits can be formed between the apertures  38  of the inflator  26  and the opening  26  of the beam  16  to direct the expanding gases therebetween. Since the open ends of the air bag  32  are sealingly attached to the interior walls  51  of the chute  50 , the expanding gases in the chute  50  are directed into the air bag  32 . Expansion of the air bag  32  breaks the thin walled members  55  and forces the door  56  to its deployed position  58 , thereby permitting release of the expanding air bag, as indicated generally by broken lines  61 . 
     As stated before, it should be understood that any suitable conventional air bag inflator may be used for the inflator  26 . The inflator  26  illustrated in  FIG. 3  is a dual stage inflator in which the inflator can be actuated to two or more different states for controlling the amount and pressure of gases expelled. It is sometimes desirable to alter the amount and pressure of the expelled gas to effect the inflation force of the air bag. For example, if sensor (not shown) detect that a child or smaller adult are seated in the passenger seat adjacent the air bag inflator assembly  14 , it would be desirable to lower the inflation force of the air bag  32 . With the two separate chambers  44  and  46 , the inflator  26  can be actuated to generally three different stages corresponding to different inflation forces of the air bag  32 . For example, for a lower power deployment, the propellant within the chamber  44  can be energized to excite the release of gas from the propellant. The air bag  32  is only inflated for a relatively short duration of time before the gases escape through vents formed through the air bag  32 . It is preferred that after the air bag inflation event has generally ended, the propellant in the other chamber  46  is later ignited, such as about 120 milliseconds thereafter. This second ignition removes live propellant from the inflator  26 . For a medium power deployment, the propellant within the chamber  44  is energized to excite the release of gas from the propellant, and then in a much shorter duration of time, such as about 17 milliseconds, the propellant within the chamber  46  is ignited. For an even more powerful deployment, the second propellant within the chamber  46  can be ignited at an even earlier duration of time, such as about 3 milliseconds. 
     There is illustrated in  FIGS. 4 and 5  an alternate embodiment of a cross car beam assembly, indicated generally at  112 . Some of the structures and features of the assembly  112  are similar to the assembly shown and described with respect to  FIGS. 1 through 3  above, and therefore similar components are indicated by similar reference numbers in these Figures, but with those of  FIGS. 4 and 5  having one-hundred prefixes. 
     The assembly  112  includes an elongated hollow beam  116  having a generally tubular and circular cross section. The tubular beam  116  can be formed from an extrusion process or by rolling and welding processes. Preferably, the beam  116  has a constant cross-sectional shape along the length of the beam  116 . However, it is not required that the beam  115  have a continuous constant cross-sectional shape during its entire length. 
     The cross car beam assembly  112  does not include a separate inflator having an outer housing and sleeve as described above with respect to the inflator  26 . Instead, the assembly  112  includes an inflator assembly, indicated generally at  126 , wherein the inflator assembly  126  is integrally formed in the cross beam  116 . A wall portion  113  of the beam  116  defines the walls of the inflator assembly  126 , thereby replacing the outer housing and sleeve of the separate inflator assembly  126 . Thus, the interior  127  of the beam  116  houses a source of pressurized gases, such as a propellant cartridge or chamber  144  and initiators  148  which are electrically connected to a controller (not shown) for actuation and energizing of the inflator assembly  126  the propellant. It should be understood that any suitable source of pressurized gas can be used for an air bag inflator, as discussed above with respect to the inflator  26 . To close off the interior of the beam  116 , the inflator assembly  126  can include a pair of caps or walls  170  and  172 . Preferably, the perimeter edges of the walls  170  and  172  are substantially sealingly attached to the interior wall portions  113  to define a generally enclosed chamber  174  within the interior  127  of the beam  116 . However, a completely sealed chamber  174  is not required. Preferably, openings  176  are formed through the beam  116  to permit the flow of gases from the inflator assembly  126  to an air bag, schematically indicated at  132 . 
     The walls  170  and  172  can be any suitable structure which closes off an end of the interior  127  of the beam  116 . For example, the walls  170  and  172  can be separate plates having a shape generally corresponding to the cross sectional shape of the interior of the beam  116 . The walls  170  and  172  may be attached to the beam  116  by any suitable manner. The walls  170  and  172  of the embodiment shown in  FIG. 4  illustrate two examples of attaching the walls  170  and  172  to the beam  116 . The wall  170  is attached to the interior wall  113  of the beam  116  by a weld  180 . The weld  180  can be annular about the entire perimeter of the wall  170  or can be multiple spaced apart spot welds thereabout the perimeter of the wall  170 . The wall  170  can be a relatively flat disk shape or can include an annular tube shaped extension  182 , as shown in  FIG. 5 . Alternatively, the wall  172  can be fastened to the beam  116  by a pair of annular crimps  184  and  186  which are formed in the wall of the beam  116 . The wall  172  is trapped by the crimps  184  and  186  and prevents axial movement of the wall  172  relative to the beam  116 . The crimps  184  and/or  186  can be annular about the entire perimeter of the wall  172  or can be multiple spaced apart crimps thereabout. Of course, the walls  170  and  172  can be attached to the beam by any combination of welds and crimps. Alternatively, a wall can be attached to the beam by fasteners (not shown), such as threaded fasteners, extending through openings formed through the walls of the beam  116 . 
     The cross car beam assembly  112  may also include an optional strengthening member, such as defined by a sleeve  190 . The sleeve  190  is attached to beam  116  adjacent the inflator assembly  126  to provide added strength to the beam  116 . The sleeve  190  can be attached to the outer surface of the beam  116 , as shown in  FIGS. 4 and 5 , or can be attached to the inner surface, thereby defining a portion of the inflator assembly  126 . The sleeve  190  generally provides for an increased thickness of the beam  116  at the region adjacent the inflator assembly  126 , without altering the cross-sectional shape of the beam  116 . 
     A folded portion of the air bag  132  can be disposed at a spaced apart relationship to the beam  116 , as shown in  FIG. 5 . To direct the flow of gases from the inflator assembly  126 , the cross car beam assembly  112  can include a chute  150 . Note that the chute  150  is mounted on the beam  116  differently than the mounting of the chute  50  to the beam  16  of  FIG. 2 . 
     Referring to  FIG. 5 , the chute  150  includes a semi-cylindrical portion  192  which is disposed over the beam  116  and sleeve  190 . An extension  194  extends from the portion  192  and houses the air bag  132 . As best shown schematically in  FIG. 5 , a left-hand portion  200  of the air bag  132  is disposed over the left-hand portion of the beam  116  and the sleeve  190 . The chute  150  covers the portion  200 . The portion  200  includes openings (not shown) through which the beam  116  and the sleeve  190  laterally extend. Preferably, the portion  200  is substantially sealingly engaged with the beam  116  and/or the sleeve  190 . The cross car beam assembly  112  can be pre-assembled and packaged and installed as one unit when installed into the vehicle or an instrument panel. A door (not shown), similar in function and/or structure as the door  56  described above, can cover an opening  202  of the chute  150 . 
     The inflator assembly  126  operates in a similar manner as the inflator assembly  26  described above. Upon detection of an impact condition in which the air bag  132  is to be deployed, a controller energize the initiator  148 , which in turn energizes the propellant within the respective chamber  144 . Excitation of the propellant causes an expansion of gas within the chamber  174  of the inflator assembly  126  defined by the wall portion  113  of the beam  116  and the walls  170  and  172 . The gases are then forced through one or more of the openings  176  formed through the beam  116  and one or more openings  208  formed through the sleeve  190 . The expanded gases are then directed into the interior of the air bag  132 , thereby causing the air bag  132  to unfold and deploy. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.