TRANSVERSE SUPPORT STRUCTURE FOR AN INSTRUMENT PANEL IN A VEHICLE

Abstract: A cross car support structure (16) of an instrument panel assembly (14) is provided for attachment to the vehicle side structure (10). The cross car support structure (16) includes a one-piece, integrally molded beam (40) preferably made entirely of plastic. The beam (40) preferably includes a plurality of laterally extending, upwardly opening, U-shaped duct channels (20) having upwardly facing edges (21). The cross car support structure (16) also preferably includes an instrument panel cover (60) including a substrate layer (67) having a bottom surface (77). The bottom surface (77) of the substrate layer (67) of the instrument panel cover (60) is continuously secured to the upwardly facing edges (21) of the beam (40) so that the continuously secured instrument panel cover (60) interconnects the upwardly facing edges (21) and stiffens the beam (40) such that the beam (40) and the continuously secured instrument panel cover (60) cooperatively provide the entire cross car support structure (16) for the instrument panel assembly (14).

Description: TRANSVERSE SUPPORT STRUCTURE FOR AN INSTRUMENT PANEL IN A VEHICLE TECHNICAL FIELD This invention relates to a cross car support structure for an instrument panel assembly in a vehicle. BACKGROUND OF THE INVENTION It is known in the prior art to provide cross car support structure for an instrument panel assembly in a vehicle. The typical cross car support structure must support many instrument panel components, such as steering wheels, air bag modules, and HVAC systems. Traditionally, most cross car support structures include a metal beam made of stamped steel or cast magnesium. It has also been suggested to provide cross car beams having composite compositions or plastic compositions reinforced with metal. When mainly plastic or composite-type cross car beams have been employed, they are typically composed of several pieces which have very complex shapes and which are stacked together and attached in a complicated manner to provide sufficient strength or require additional metal cross beams or mounting brackets. Also in the prior art, the typical cross car beams require separate duct work for HVAC systems adding more parts to the assembly. In addition, the prior art cross car support structures require the instrument panel assembly to include a separate decorative top cover which is intermittently attached to the cross car support structure, such as by screws or other traditional fasteners. SUMMARY OF THE INVENTION Advantageously, an embodiment of the invention preferably provides a cross car support structure of an instrument panel having a cross car beam which is preferably made entirely of plastic. In addition, the beam preferably has a relatively simple shape which is easy to manufacture and mold. Also advantageously, duct channels for the HVAC system may be integrally formed with the shape of the beam such that separate duct channels are not needed. Furthermore, the instrument panel cover is preferably used as a key structural portion of the cross car support structure and the size and geometry of the instrument panel cover provide substantial stiffness to the cross car support structure so that, together with the single one-piece beam, the entire cross car support structure including the duct channels is provided without the use of heavy metal cross beams, additional metal support brackets, or complex-shaped, multiple layers of plastic members. A cross car support structure in accordance with the present invention is characerized by the features specified in claims 1. These advantages are accomplished in a preferred embodiment of the present invention by providing a cross car support structure of an instrument panel assembly for attachment to vehicle side structure. The cross car support structure includes a one-piece, integrally molded beam, the beam having at least one end connected to the vehicle side structure. In addition, the beam preferably includes a plurality of laterally extending, upwardly opening, U-shaped duct channels preferably lying in a same generally horizontal plane. The duct channels each include a rearward generally vertical wall and a forward generally vertical wall with the duct channels sharing one of the generally vertical walls therebetween such that one of the forward generally vertical walls of one of the duct channels provides one of the rearward generally vertical walls for another of the duct channels. Preferably, the duct channels include a rearward primary air duct for carrying heated, cooled, and ambient air to vehicle occupants, a forward defroster duct, and a side window defogger duct positioned between the rearward primary air duct and the defroster duct. In accordance with another preferred embodiment of the invention, each of the generally vertical walls of the duct channels of the beam includes upwardly facing edges. The cross car support structure further includes an instrument panel cover including a substrate layer having a bottom surface. The bottom surface of the substrate layer of the instrument panel cover is continuously secured to the upwardly facing edges of the beam so that the continuously secured instrument panel cover interconnects the upwardly facing edges and stiffens the beam such that the beam and the continuously secured instrument panel cover cooperatively provide the entire cross car support structure for the instrument panel assembly. The bottom surface of the substrate layer of the instrument panel cover is continuously secured to preferably the substantially entire surface of the upwardly facing edges such as by adhesively bonding or vibration welding. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of the cross car support structure for an instrument panel assembly with the instrument panel cover partially broken away; and Figure 2 is a sectional view taken along line 2-2 of Figure 1. DESCRIPTION OF AN EMBODIMENT OF THE INVENTION A typical passenger vehicle includes vehicle side structure 10, such as the A-pillar structure, which defines the forward portion of an interior passenger compartment 11. The interior passenger compartment 11 includes an instrument panel assembly 14 which is positioned forward of the occupants (not shown). The instrument panel assembly 14 includes cross car support structure 16 on which numerous interior components are mounted and supported, such as HVAC system components 18, a steering wheel (not shown), and air bag modules (not shown) through the use of suitable brackets and fasteners (not shown). The entire cross car support structure 16 and duct channels 20 for an HVAC system are advantageously provided by a single plastic beam 40 continuously joined to an instrument panel cover 60, as will now be described. The beam 40 preferably is one-piece and integrally molded preferably entirely of plastic material. Preferably the plastic material has a flexural modulus of at least 800,000 psi. The plastic beam 40 has opposing flanged ends 42 for connection to the vehicle side structure 10 on opposite sides of the vehicle. The flanged ends 42 each preferably include end apertures 43 through which fasteners can be received to secure the ends 42 of the plastic beam 40 to the vehicle side structure 10. It will further be appreciated that the ends 42 of the plastic beam 40 may also be attached to the vehicle side structure 10 in other suitable manners, such as bonding or welding. Advantageously, the duct channels 20 for the HVAC system are integrally molded with the plastic beam 40 to greatly reduce the number of components in the instrument panel assembly 14. Accordingly, the plastic beam 40 includes a plurality of upwardly opening, U-shaped duct channels 20. The duct channels 20 preferably lie in the generally same horizontal plane and are generally lined up forward and rearward of each other. The duct channels 20 extend laterally across the vehicle between the flanged ends 42 and have individual lateral lengths as needed. Preferably, the plastic beam 40 includes three duct channels being a rearward primary air first duct 22, a forward defroster third duct 35, and a side window defogger second duct 28 positioned between the first duct 22 and the third duct 35. It will be appreciated that the third duct 35 is preferably shorter and centrally located to accomplish its objective of defrosting a vehicle windshield 12. The first duct 22 preferably includes central and curved end outlets 23 directed towards the vehicle occupants for matably aligning with first vented openings 62 in the instrument panel cover 60 for delivering heated, cooled, or ambient air to the vehicle occupants. The outlets 23 define forwardly facing edges 26 which may also be continuously secured to the instrument panel cover 60, as described hereinafter. The second duct 28 preferably has closed curved ends 29 matably aligned with upper second vented openings 63 in the instrument panel cover 60 located to accomplish the objective of defrosting side windows (not shown). However, it will be appreciated that these specific duct channels 20 and functions may be interchangeable between the forward and rearward positions and that additional duct channels 20 may be added or duct channels 20 with other purposes in the HVAC system may be added or subtracted. For example, the third duct 35 could be provided as a separate piece. However, it is very desirable that at least two duct channels 20 extend laterally across the vehicle and be integrally formed with the plastic beam 40. The integral vertical height and the integral horizontal forward to rearward order of the plurality of duct channels 20 provides the geometry and stiffness needed for the cross car support structure 16. In addition, the duct channels 20 preferably lie in generally the same horizontal plane next to each other so that there is a horizontal surface comprised of upwardly facing edges 21 of the duct channels 20 for convenient continuous attachment of the plastic beam 40 to the instrument panel cover 60, as described hereinafter. The first duct channel 22 includes a first rearward generally vertical wall 24 and a first forward generally vertical wall 25. The second duct channel 28 includes a second rearward generally vertical wall 30 and a second forward generally vertical wall 31. The third duct channel 35 includes a third rearward generally vertical wall 36 and a third forward generally vertical wall 37. It will be appreciated that the first forward generally vertical wall 25 also provides the second rearward generally vertical wall 30 and that the second forward generally vertical wall 31 also provides the third rearward generally vertical wall 36. Thus, each of duct channels 20 shares one of the generally vertical walls 25, 30, 31, 36 therebetween such that one of the forward generally vertical walls 25, 31 of one of the duct channels 20 provides one of the rearward generally vertical walls 30, 36 for another of the duct channels 20 to reduce the number of components and increase stiffness of the plastic beam 40. Each of the generally vertical walls 24, 25, 30, 31 , 36, 37 of the duct channels 20 of the plastic beam 40 includes upwardly facing edges 21 which preferably lie in a generally horizontal plane. Substantially the entire surface area of the upwardly facing edges 21 is preferably continuously secured to the instrument panel cover 60 to cooperatively provide the cross car support structure 16, as described further below. The cross car support structure 16 further includes the instrument panel cover 60. The instrument panel cover 60 includes a structural substrate layer 67 made of a relatively stiff plastic material, an overlying foam layer 68, and an outer skin layer 69. It will be appreciated that the foam and skin layers 68, 69 are decorative and could be eliminated such that the substrate layer 67 made of a material such as an injection molded thermoplastic could serve as both the substrate layer 67 and the decorative outer surface. The instrument panel cover 60 and the corresponding substrate layer 67 are preferably L-shaped and include a generally horizontal upper portion 70 and an integrally formed downwardly extending lower portion 71. The substrate layer 67 is integrally molded of a plastic material generally into the L-shape with suitable openings for features such as vents 73, a console 74, and a glove box 75. A bottom surface 77 of the generally horizontal upper portion 70 of the substrate layer 67 is generally planar for abutting and engaging substantially the entire surface of the upwardly facing edges 21 of the duct channels 20 for continuous attachment thereto. The bottom surface 77 of the substrate layer 67 of the instrument panel cover 60 is continuously secured to the upwardly facing edges 21 of the plastic beam 40 wherein the continuously secured instrument panel cover 60 interconnects the upwardly facing edges 21 and stiffens the plastic beam 40 such that the plastic beam 40 and the continuously secured instrument panel cover 60 cooperatively provide the entire cross car support structure 16 for the instrument panel assembly 10. Preferably this continuous attachment of the plastic beam 40 to the substrate layer 67 of the instrument panel cover 60 is accomplished by adhesive bonding, by vibration welding, by infrared welding, by hot plate welding, or by any other suitable attachment methods that will integrally connect the majority of or the entire surface area of the upwardly facing edges 21 of the plastic beam 40 with the bottom surface 77 of the substrate layer 67 instrument panel cover 60. The plastic beam 40 and the substrate layer 67 of the instrument panel cover 60 are continuously joined by any method which continuously connects or melts them together so that the plastic beam 40 and instrument panel cover 60 act as a single cross car support structure 16. The instrument panel cover 60 and plastic beam 40 must be sufficiently continuously joined to cooperatively act as a single cross car support structure 16 having a sufficiently large size and geometry to generate a high moment of inertia and stiffness for providing sufficient torsional rigidity to the vehicle. It will be appreciated that preferably only the upper portion 70 of the instrument panel cover 60 is continuously secured to the plastic beam 40. However, the substrate layer 67 on the lower portion 71 of the instrument panel cover 60 may also be continuously secured to the forwardly facing edges 26 of the duct channels 20 of the plastic beam 40 for additional rigidity. Optionally, a lower edge 72 of the lower portion 70 of the instrument panel cover 60 may be anchored to any suitable vehicle structure, such as a lower tie bar 15. It will be understood that a person skilled in the art may make modifications to the preferred embodiment shown herein within the scope and intent of the claims. For example, although the instrument panel cover 60 is shown as a one-piece cover having an integrally molded L-shaped substrate layer 67, it will be appreciated that the generally horizontal upper portion 70 of the instrument panel cover 60 may be formed separately and secured to the downwardly extending lower portion 71 to form the L-shaped instrument panel cover 60. While the beam 40 is most preferably integrally molded entirely of a plastic material, it will be appreciated that the beam 40 having upwardly facing edges 21 could also be one-piece integrally molded of other lightweight composite-type or lightweight metallic materials, such as aluminum or magnesium, with the instrument panel cover 60 continuously secured thereto.

Claims: 1. A cross car support structure (16) of an instrument panel assembly (14) for attachment to vehicle side structure (10), the cross car support structure (16) characterized by a one-piece, integrally molded beam (40), the beam having at least one end (42) connected to the vehicle side structure (10), the beam (40) including a plurality of laterally extending, upwardly opening, U-shaped duct channels (20), each of the duct channels (20) lying in a same generally horizontal plane, each of the duct channels (20) including a rearward generally vertical wall (24, 30, 36) and a forward generally vertical wall (25, 31, 37), each of the duct channels (20) sharing one of the generally vertical walls (25, 30, 31, 36) therebetween such that one of the forward generally vertical walls (25, 31) of one of the duct channels (20) provides one of the rearward generally vertical walls (30, 36) for another of the duct channels (20). 2. The cross car support structure (16) of claim 1 wherein the duct channels (20) include a rearward first duct (22), a forward third duct (35), and a second duct (28) positioned between the rearward first duct (22) and the forward third duct (35). 3. The cross car support structure (16) of claim 1 wherein each of the generally vertical walls (24, 25, 30, 31, 36, 37) of the duct channels (20) of the beam (40) includes upwardly facing edges (21) and wherein the cross car support structure (16) further includes an instrument panel cover (60) including a substrate layer (67) having a bottom surface (77), the bottom surface (77) of the substrate layer (67) of the instrument panel cover (60) being continuously secured to the upwardly facing edges (21) of the beam (40) wherein the continuously secured instrument panel cover (60) interconnects the upwardly facing edges (21) and stiffens the beam (40) such that the beam (40) and the continuously secured instrument panel cover (60) cooperatively provide the cross car support structure (16) for the instrument panel assembly (14). 4. The cross car support structure (16) of claim 3 wherein the bottom surface (77) of the substrate layer (67) of the instrument panel cover (60) is adhesively bonded to the upwardly facing edges (21) of the beam (40). 5. The cross car support structure (16) of claim 3 wherein the bottom surface (77) of the substrate layer (67) of the instrument panel cover (60) is vibration welded to the upwardly facing edges (21) of the beam (40). 6. The cross car support structure (16) of claim 3 wherein the substrate layer (67) of the instrument panel cover (60) is L-shaped and includes a generally horizontal upper portion (70) and a downwardly extending lower portion (71) and wherein the upper portion (70) of the instrument panel cover (60) is continuously secured to the upwardly facing edges (21) of the beam (40). 7. The cross car support structure (16) of claim 3 wherein the upwardly facing edges (21) lie in a same generally horizontal plane. 8. The cross car support structure (16) of claim 1 further characterized by the one-piece, integrally molded beam (40) being formed entirely of plastic.

Inventors: MERRIFIELD RICHARD ALLEN, RANDALL DOUGLAS ALLEN, MERRIFIELD, RICHARD, ALLEN, RANDALL, DOUGLAS, ALLEN
Applicants: GEN MOTORS CORP, GENERAL MOTORS CORPORATION
Application year: 1997
Main classification: B62D25
IPC codes: B60H1, B60K37, B62D25