Vehicular cross car beam assembly having an integral air bag inflator

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.

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.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, there is illustrated inFIG. 1, an instrument panel10and a cross car beam assembly, indicated generally at12in accordance with the present invention. As will be discussed in detail below, the cross car beam assembly12includes an air bag inflator assembly14integrally mounted with cross car beam16of the assembly12. This arrangement provides increased space in the instrument panel for other components, and may also help reduce the weight and cost of the instrument panel10and/or cross car beam assembly12. This arrangement may also permit shorter depth instrument panels.

The instrument panel12is generally positioned underneath the windshield of the vehicle and rearward of the vehicle firewall. The instrument panel10generally extends along the entire width of the interior of the passenger compartment of the vehicle. The instrument panel10can be attached to the vehicle frame by any suitable manner. For example, the ends and rear portion of the instrument panel10can be directly attached to portions of the vehicle frame. The instrument panel10can 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 assembly12generally includes the elongated hollow beam16and the air bag inflator assembly14. The beam16preferably extends laterally across the interior of the passenger compartment. The ends of the beam16can be attached to the vehicle frame, such as at the cowl sides. Alternatively, the beam16can be attached to the instrument panel10. The beam16is 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 beam16helps prevent the sides of the vehicle from intruding into the interior of the passenger compartment.

In a preferred embodiment, the beam16has a generally constant cross-sectional shape along its length to minimize bending and/or collapsing upon itself. However, it should be understood that the beam16is 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 beam16may also have any suitable cross-sectional shape, such as circular, rectangular, or any unsymmetrical shape. The beam16may 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 inFIG. 2, the beam16is formed by a stamped part19having a generally hat-shaped cross-sectional shape defining an open end20. A generally flat plate22is attached to the open end20of the part19. The part19and plate22form 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 plate22has one or more openings24formed 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 beam16.

In the embodiment of the cross car beam assembly12illustrated inFIG. 2, a separate inflator26is disposed within the interior27of the hollow beam16. The inflator26can be mounted in the beam16by any suitable manner, such as by threaded fasteners30. The inflator26can 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 bag32for proper inflation of the air bag during an impact condition, such as a collision. The inflating air bag32helps protect the occupant of the passenger seat positioned rearward of the air bag inflator assembly14. An example of a suitable inflator26is shown inFIG. 3.

The inflator26includes a separate canister including a cylindrical outer housing36having one or more apertures38formed therein. An inner sleeve40is disposed in the outer housing36and also includes one of more apertures42. If desired, a rupture disk may be inserted in the apertures42which helps prevent contaminants from entering the interior of the sleeve40. The inflator26preferably includes one or more propellant cartridges or chambers44and46which house propellant therein. The cartridges or chambers44and46may 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 inflator26includes initiators48which are electrically connected to a controller (not shown) for actuation and energizing of the inflator26. Note that the beam16may include apertures (not shown) to provide a pathway for wiring electrically connecting the initiators48to the controller.

Commonly, the desired position of the beam16is 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 bag32is spaced rearwardly from the inflator26, such as by a distance D shown inFIG. 2. It is generally desirable to position the folded air bag32close to the outer surface of the instrument panel to provide proper deployment of the air bag32. To direct the expelled gas from the inflator26to the air bag32, an optional chute50is provided. The chute50can be mounted to the beam16and/or a portion of the instrument panel10. Preferably, the folded air bag32is housed in the chute50. As shown inFIG. 2, the air bag32includes an open end52facing forward towards the openings24of the beam16. The open end52of the air bag32can be sealingly attached to the interior walls51of the chute50. In the embodiment illustrated inFIG. 2, an air bag door56is integrally formed with the chute50. The door56is attached to the instrument panel10via a hinge57or a tether (not shown). The door56covers the air bag32when in its non-deployed state. The door56is movable to a deployed position, indicated generally by broken lines58upon expansion of the air bag32. The door56can be integrated into the chute50as shown inFIG. 2. Preferably, the door56is attached to the chute50by thin walled members55which break open to separate a portion of or the entire door56from the chute50upon deployment of the air bag32. Alternatively, the door56can be integrally formed in the instrument panel12such as by a conventional break-away seam, as is commonly known in the art.

Upon detection of an impact condition in which the air bag32is to be deployed, a controller energizes one or both of the initiators48, which in turn energizes the propellant within the respective chamber44and46. Energizing of the propellant causes an expansion of gas within the interior of the sleeve40which is forced outwardly through the apertures42and the apertures38of the outer housing36. As shown inFIG. 2, the expanding gas is directed into the interior27of the beam16and through the openings24into the interior of the chute50. The expanding gases can be directed from the interior27of the beam16to the chute50by any suitable manner. Preferably, at least the ends of the beam16are capped so that the expanding gases are directed through the openings24. More preferably, the interior27of the beam16is closed off adjacent the inflator26so that the inflator26is disposed in a generally small chamber within the interior of the beam16. Alternatively, additional chutes or conduits can be formed between the apertures38of the inflator26and the opening26of the beam16to direct the expanding gases therebetween. Since the open ends of the air bag32are sealingly attached to the interior walls51of the chute50, the expanding gases in the chute50are directed into the air bag32. Expansion of the air bag32breaks the thin walled members55and forces the door56to its deployed position58, thereby permitting release of the expanding air bag, as indicated generally by broken lines61.

As stated before, it should be understood that any suitable conventional air bag inflator may be used for the inflator26. The inflator26illustrated inFIG. 3is 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 assembly14, it would be desirable to lower the inflation force of the air bag32. With the two separate chambers44and46, the inflator26can be actuated to generally three different stages corresponding to different inflation forces of the air bag32. For example, for a lower power deployment, the propellant within the chamber44can be energized to excite the release of gas from the propellant. The air bag32is only inflated for a relatively short duration of time before the gases escape through vents formed through the air bag32. It is preferred that after the air bag inflation event has generally ended, the propellant in the other chamber46is later ignited, such as about 120 milliseconds thereafter. This second ignition removes live propellant from the inflator26. For a medium power deployment, the propellant within the chamber44is 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 chamber46is ignited. For an even more powerful deployment, the second propellant within the chamber46can be ignited at an even earlier duration of time, such as about 3 milliseconds.

There is illustrated inFIGS. 4 and 5an alternate embodiment of a cross car beam assembly, indicated generally at112. Some of the structures and features of the assembly112are similar to the assembly shown and described with respect toFIGS. 1 through 3above, and therefore similar components are indicated by similar reference numbers in these Figures, but with those ofFIGS. 4 and 5having one-hundred prefixes.

The assembly112includes an elongated hollow beam116having a generally tubular and circular cross section. The tubular beam116can be formed from an extrusion process or by rolling and welding processes. Preferably, the beam116has a constant cross-sectional shape along the length of the beam116. However, it is not required that the beam115have a continuous constant cross-sectional shape during its entire length.

The cross car beam assembly112does not include a separate inflator having an outer housing and sleeve as described above with respect to the inflator26. Instead, the assembly112includes an inflator assembly, indicated generally at126, wherein the inflator assembly126is integrally formed in the cross beam116. A wall portion113of the beam116defines the walls of the inflator assembly126, thereby replacing the outer housing and sleeve of the separate inflator assembly126. Thus, the interior127of the beam116houses a source of pressurized gases, such as a propellant cartridge or chamber144and initiators148which are electrically connected to a controller (not shown) for actuation and energizing of the inflator assembly126the 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 inflator26. To close off the interior of the beam116, the inflator assembly126can include a pair of caps or walls170and172. Preferably, the perimeter edges of the walls170and172are substantially sealingly attached to the interior wall portions113to define a generally enclosed chamber174within the interior127of the beam116. However, a completely sealed chamber174is not required. Preferably, openings176are formed through the beam116to permit the flow of gases from the inflator assembly126to an air bag, schematically indicated at132.

The walls170and172can be any suitable structure which closes off an end of the interior127of the beam116. For example, the walls170and172can be separate plates having a shape generally corresponding to the cross sectional shape of the interior of the beam116. The walls170and172may be attached to the beam116by any suitable manner. The walls170and172of the embodiment shown inFIG. 4illustrate two examples of attaching the walls170and172to the beam116. The wall170is attached to the interior wall113of the beam116by a weld180. The weld180can be annular about the entire perimeter of the wall170or can be multiple spaced apart spot welds thereabout the perimeter of the wall170. The wall170can be a relatively flat disk shape or can include an annular tube shaped extension182, as shown inFIG. 5. Alternatively, the wall172can be fastened to the beam116by a pair of annular crimps184and186which are formed in the wall of the beam116. The wall172is trapped by the crimps184and186and prevents axial movement of the wall172relative to the beam116. The crimps184and/or186can be annular about the entire perimeter of the wall172or can be multiple spaced apart crimps thereabout. Of course, the walls170and172can 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 beam116.

The cross car beam assembly112may also include an optional strengthening member, such as defined by a sleeve190. The sleeve190is attached to beam116adjacent the inflator assembly126to provide added strength to the beam116. The sleeve190can be attached to the outer surface of the beam116, as shown inFIGS. 4 and 5, or can be attached to the inner surface, thereby defining a portion of the inflator assembly126. The sleeve190generally provides for an increased thickness of the beam116at the region adjacent the inflator assembly126, without altering the cross-sectional shape of the beam116.

A folded portion of the air bag132can be disposed at a spaced apart relationship to the beam116, as shown inFIG. 5. To direct the flow of gases from the inflator assembly126, the cross car beam assembly112can include a chute150. Note that the chute150is mounted on the beam116differently than the mounting of the chute50to the beam16ofFIG. 2.

Referring toFIG. 5, the chute150includes a semi-cylindrical portion192which is disposed over the beam116and sleeve190. An extension194extends from the portion192and houses the air bag132. As best shown schematically inFIG. 5, a left-hand portion200of the air bag132is disposed over the left-hand portion of the beam116and the sleeve190. The chute150covers the portion200. The portion200includes openings (not shown) through which the beam116and the sleeve190laterally extend. Preferably, the portion200is substantially sealingly engaged with the beam116and/or the sleeve190. The cross car beam assembly112can 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 door56described above, can cover an opening202of the chute150.

The inflator assembly126operates in a similar manner as the inflator assembly26described above. Upon detection of an impact condition in which the air bag132is to be deployed, a controller energize the initiator148, which in turn energizes the propellant within the respective chamber144. Excitation of the propellant causes an expansion of gas within the chamber174of the inflator assembly126defined by the wall portion113of the beam116and the walls170and172. The gases are then forced through one or more of the openings176formed through the beam116and one or more openings208formed through the sleeve190. The expanded gases are then directed into the interior of the air bag132, thereby causing the air bag132to unfold and deploy.