Abstract:
A steering column mounting bracket is provided with break-away bars integrally formed therewith to allow for a consistent break-away force and reduce noise in the cabin of an automobile. The break-away bars will allow for axial compression of the steering shaft during an accident involving a collision of an automobile.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to steering column support structures, and more particularly to a steering column support structure including break-away bars that securely hold the steering column to the instrument panel without hindering the collapse of the steering column during an accident. 
     BACKGROUND 
     It is desirable to have a steering column of a vehicle that is securely attached to the frame of the automobile so as to ensure safe operation thereof for the life of the automobile. Generally, this is accomplished by bolting the steering column to the instrument panel which is further secured to the frame of the automobile. However, it is further desirous to allow for the steering column to disengage from the instrument panel upon the application of a force during an accident. 
     It is known in the art to attempt to solve these contradictory goals by using polymer capsules to support the mounting bracket (such as disclosed in commonly assigned U.S. Pat. No. 5,390,955 herein incorporated by reference) and the steering column that are designed in such a way as to break away under a given force. Thus, the steering column is allowed to break away from the instrument panel upon the application of a force in the event on an accident. 
     Further, the polymer capsules may fall out during installation and may change in shape which can cause the capsules to weaken or “creep.” This creep can cause buzz/squeak/rattle (BSR) problems which are unwanted during the operation of the vehicle. Furthermore, the polymer capsules are relatively fragile and can become damaged prior to installation thus requiring the disposal of the part. 
     SUMMARY OF THE INVENTION 
     The present invention provides a break-away bar that will overcome the disadvantages of the prior art polymer capsules. It is an object of this invention to form these break-away bars from the same material as the remainder of the steering column mounting bracket. The magnesium or other metallic material of which the steering column mounting bracket is made is rigid and is not susceptible to being misshapen and is much more predictable than a polymeric material. Thus, the break-away bar will have a consistent break-away load, not be susceptible to BSR, and not break unintentionally during installation. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood however that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a perspective view illustrating the attachment of the steering column mounting bracket to the instrument panel; 
     FIG. 2 is a detail view of the break-away bar of the mounting bracket is affixed to a support bracket of the instrument panel; 
     FIG. 2 a  is a cross-sectional view taken along line  2   a — 2   a  of FIG. 2; 
     FIG. 3 is a perspective view of a mounting bracket containing four mounting areas with a first embodiment of the invention; and 
     FIG. 4 is a perspective view of a mounting bracket containing two mounting areas with a second embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates the mounting bracket  10  in its assembled orientation with the support bracket  13  and the instrument panel  12 . However, for illustrative purposes, FIG. 1 does not include the fasteners affixing the mounting bracket  10  to the support bracket  13 . Such fasteners  30 ,  32  are shown in place, in detail, in FIGS. 2 and 2 a  as will be described in greater detail herein. 
     Referring to FIG. 1 the mounting bracket  10  includes a main body  11  through which a bore  24  is defined for receiving a steering shaft (not shown). On either side of the main body  11  are a pair of rearward flanges  14  and a pair of forward flanges  22 . The pair of rearward flanges  14  include a lower flange body  15  and an upper flange structure  25  which define openings  28 . Openings  28  allow for limited movement of mounting bracket  10  relative to support bracket  13 . Break-away assemblies  16  are contained within the openings  28 . The break-away assemblies  16  include a break-away bar  18  interconnected to the inside of the openings  28 . The geometry of the break-away bar  18  may be altered to provide a selected force under which the break-away bar  18  will release. The break-away assembly  16  further includes a web body  19 . Together break-away bar  18  and web body  19  define a fastener opening  20 . The fastener opening  20  allows for the insertion of fasteners to affix the mounting bracket  10  to the support bracket  13 . 
     FIG. 2 is a detail view of a flange  14  of the mounting bracket  10  affixed to the support bracket  13 . Break-away bar  18  and web body  19  are inside openings  28  of the flange  14 . A bolt  30  is inserted through an opening  34  in the support bracket  13  and opening  20  in the break-away bar assembly  16 . The bolt  30  is then secured into place with a nut  32 . The head of the bolt  30  is disposed against support bracket  13  and nut  32  is disposed against break-away bar  18  and web body  19 . Through this interlocking the mounting bracket flange  14  is affixed to the support bracket  13  through break-away bar  18  and web body  19 . 
     FIG. 2 a  is a cross-sectional view of the same detail as shown in FIG.  2 . Flange  14  includes the flange body  15  and the upper flange structure  25  which define openings  28 . The flange  14  further includes the break-away bar assembly  16  which includes the break-away bar  18  and web body  19 . The fastener opening  20  is defined by break-away bar  18  and web body  19 . In this view the head of bolt  30  is disposed against support bracket  13  while bolt shaft  31  extends through fastener opening  20  in mounting bracket  10 . Nut  32  engages the bolt shaft  31  and is disposed against break-away bar  18  and web body  19 . 
     FIG. 3 illustrates a perspective view from the front side of mounting bracket  10 . The mounting bracket  10  includes a main body  11  and a bore  24  through which a steering shaft (not shown) may be inserted. Formed to the sides of the main body  11  are flanges. Included in this embodiment are forward flanges  22  and rearward flanges  14  placed on opposite sides of main body  11 . Rearward flanges  14  include an upper flange structure  25  defining an opening  28 . Upper flange structure  25  provides a limit to the movement allowed of the mounting bracket  10 . Contained within the opening  28  of the rearward flanges  14  are break-away bar assemblies  16 . In this embodiment, break-away bar  18  has a different geometry of that shown in FIGS. 1 and 2 (in order to illustrate alternative designs). The break-away bar geometry can be generally described as a uniform bar, pinched in its center and distal ends, the distal ends of the break-away bar  18 ′ are affixed to the interior of the flange  14 . The geometry of the break-away bar  18 ′ may be altered to alter the force required to release its hold. When the break-away bar  18 ′ is broken the mounting bracket  10  is free to move along its axis. 
     Illustrated in FIG. 4 is a second embodiment of the present invention wherein like reference numerals designate similar elements. The mounting bracket  50  of this embodiment includes a main body  111  including a bore  124  through the main body  111  to receive a steering shaft (not shown) when fully assembled. However, this embodiment includes only rearward flanges  31  and eliminates the upper flange structures  25  of FIG.  3 . Further, the break-away bar  34  of the break-away bar assembly  36  is demonstrated with an altered geometry from that disclosed in FIG.  3 . In addition, due to the lack of upper flange structure in this embodiment the mounting bracket  50  is not hindered in its movement once the break-away bars  34  release. 
     Continuing reference to FIGS. 3 and 4 it can be seen that features from the two embodiments may be interchanged creating several variations (two are illustrated). Thus, for example, the break-away bar  18  of FIG. 3 may be placed in the mounting bracket  50  of FIG.  4 . In a second example the upper flange structure  25 , as in FIG. 3, may be placed around the break-away bar  34  of FIG.  4  and the upper flange structure  25  of the embodiment of FIG. 3 may be removed as in FIG.  4 . 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.