Abstract:
A bumper beam comprises a first and second channel members, a plate, and a mount. Each of the first and the second channel members being an elongated member that has a length between two opposing ends and a generally U-shaped cross section with a web that has two opposing edges and a pair of flanges that project in the same general direction from the two opposing edges of the web to terminal ends. The two web edges and the flanges extending along the length. The plate extends between and connecting the first and the second channel members. The mount is connected with one of the first and the second channel members whereby the bumper beam is connected with a frame member of a vehicle.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This is a continuing non-provisional patent application of co-pending U.S. provisional Patent Application Ser. No. 60/161,632, entitled Bumper Beam Having Double Open Sided Channel Members and filed on Oct. 27, 1999 by Patrick M. Glance, now co-pending, the disclosure of which is incorporated here by reference. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     Currently, many automotive bumper beams are roll formed from high strength steel. These beams are roll formed and seam-welded to create a closed section bumper beam that is an efficient light weight structure. The limitations of the roll form process permit only a constant cross-sectional shape, and the limits of high strength steel permits only limited plan view sweep (curvature) being formed into the beams. For rear bumper beams, where a straight or small sweep beam is required, a roll formed high strength beam is well suited. For front end vehicle applications, where the current styling trends require large plan view sweep, however, the roll formed section cannot follow the sweep of the fascia. This results in filling the excess space between the beam and fascia with absorber foam, or utilizing an extruded aluminum or stamped beam. An extruded aluminum beam has higher sweep capability, but is more expensive. Both extruded aluminum and roll formed beams have the disadvantage of a constant cross-sectional shape. This forces the bumper designer to utilize the maximum strength cross section throughout the length of the bumper, although it is not required along the entire length and is typically only required at the center. 
     Thus, one may easily see the need to provide a high strength bumper beam that has high sweep capability and the capability to vary the cross section depth. This will permit use of high strength steel in a tailored cross section. The result will be an extremely efficient, light weight structure that will allow secondary cost savings by eliminating unnecessary absorber and fascia package space. 
     BRIEF SUMMARY OF THE INVENTION 
     The approach to this task is to create two ultra high-strength, shallow, open C-sections, by roll forming or press braking, and sweeping them individually. The two sections are welded to transverse support members, such as “bulkhead plates”, between the c-section assembly to form a bumper beam structure. The bulkhead plates can be corrugated to provide beam crush during a high speed vehicle crash. This is desirable to provide additional energy absorption and crush space. A second alternative is to incorporate energy absorbing structures, such as injection molded cones, or deformable solids, for example, between the C-Sections to absorb additional energy during a high speed crash when the C-Sections will be crushed. 
     The sweeping of the shallow open sections can be more easily accomplished than sweeping a deep closed section. This permits use of even higher strength steels, including materials that have a yield strength of about two hundred twenty thousand pounds per square inch (220 kips) or other metals and composite materials. Each C-section can be swept to a different sweep to create a variable cross section depth beam when the two are assembled to form the final beam. The variable cross section permits tailored bending stiffness along the length of the beam and results in less material usage, lower mass, and lower cost than a constant section beam. 
     The structural concept of the double C-section also has application to other beam applications, including side door guard beams, for example. Many design variations of the bulkheads are also, possible. They could be simple plates, corrugated, plates with end flanges, a W-section, or serpentine section, for example. A main function of the bulkheads is to weld the front and rear C-sections together. Variations in the design of the front and rear sections are also possible, and are covered within the spirit of this disclosure. 
     A secondary function of the bulkheads is to provide additional energy absorption during high speed impact and crush of the vehicle front end. Variations in the design of internal, deformable bulkheads, incorporating crush energy absorbers including plastic cells, foam, epoxy composite, ceramic forms, are possible and are covered with the spirit of this disclosure. 
     These and other features, objects, and benefits of the invention will be recognized by one having ordinary skill in the art and by those who practice the invention, from the specification, the claims, and the drawing figures. 
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     FIG. 1 is a fragmentary longitudinal perspective view of a bumper assembly according to the invention; 
     FIG. 2 is a bottom plan view thereof; 
     FIG. 3 is a fragmentary longitudinal perspective view of two open sided beam members assembled into a beam according to the invention; 
     FIG. 4 is a bottom plan view thereof; 
     FIG. 5 is a cross-sectional view of an open sided beam member used in the invention; 
     FIG. 6 is the view of FIG. 3, showing optional tie plates between the channel members; 
     FIG. 7 is the view of FIG. 4, showing alternative tie plates between the channel members; 
     FIG. 8 is a fragmentary top plan view of a beam according to the invention, showing a corrugated bulkhead with fastening flanges; 
     FIG. 9 is a fragmentary top plan view of a beam according to the invention, showing a serpentine bulkhead with fastening flanges; and 
     FIG. 10 is a fragmentary longitudinal perspective view of two open sided beam members positioned as they would be assembled into a beam according to the invention, showing an alternative cross section for the channel members; and 
     FIG. 11 is a front longitudinal perspective view of a first alternative bumper assembly according to the invention; 
     FIG. 12 is a top plan view thereof; 
     FIG. 13 is a front elevational view thereof, 
     FIG. 14 is a cross-sectional view thereof along line XIV—XIV of FIG. 13; 
     FIG. 15 is a cross-sectional view thereof along line XV—XV of FIG. 13; 
     FIG. 16 is a cross-sectional view thereof along line XVI—XVI of FIG. 13; and 
     FIG. 17 is an end elevational view thereof. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of a bumper beam of the invention is generally shown in the drawing figures and identified with the reference number  10 . The bumper beam  10  includes opposing first and second channel members  12  and  14 , respectively, and at least one plate  16  that interconnects the channel members (FIGS.  1 - 7 ). The channel members  12  and  14  are preferably aligned with one another. Thus, the channel members  12  and  14  are preferably generally parallel with one another and centered relative to one another. A facia  11  can cover the front of the beam. Energy absorbers  13  can be positioned between the facia and the beam. Screw fasteners  25  screw into holes  27  in the beam to hold the facia on the beam. 
     The channel members  12  and  14  may be configured similarly or distinctly. That is to say that identical channel members may be used in both of the first and second positions. More typically, the first channel member  12  with be constructed as an arcuate channel member while the second channel member  14  is generally linear. This is not to say that the second channel member  14  cannot be an arcuate member, only that most commonly as applied to a vehicular bumper, the second channel member is expected to have a curvature, if any at all, that is relatively more straight than the first channel member  12 . 
     The two channel members  12  and  14  may also be constructed similarly or distinctly. Any of various structural materials, commonly including and not limited to metals and plastics, may be used to fabricate the channel members  12  and  14 . Use of the invention overcomes limitations of prior bumper constructions and facilitates the use of high strength steel, for example. Accordingly, any fabrication method that is appropriate to the selected material may be used. Also, a user&#39;s or manufacturer&#39;s requirements may dictate that the channel members  12  and  14  be fabricated of the same materials, or not, and with the same methods, or not. Further, structural considerations of specific installations of a bumper beam according to the invention may indicate that the two channel members  12  and  14  have the same or differing cross-sectional shapes. In one exemplary configuration, the second channel member  14  may be a length of rolled steel channel with a generally U-shaped cross section, while the first channel member  12  may be molded of a plastic with a curved contour along its length and with a generally C-shaped or semi-circular cross section. 
     As is generally shown, the first and second channel members  12  and  14 , respectively, are simple open sided channel members. More specifically each of the channel members  12  and  14  has a U-shaped or C-shaped cross section with two legs or flanges  22  and  24  extending in generally the same direction from opposing edges of a bight or web portion  26  (FIG. 5) The second channel member  14  will commonly be generally linear, while the first channel member  12  will commonly be generally arched, with the corresponding ends of the channel members meeting (FIGS.  1 - 7 ). The channel members  12  and  14  are interconnected by an array or series of the bulkheads or tie plates  16  (FIG.  3 ). Beam  14  is mounted on the frame end flanges  31  at the end of frame members  17  by fasteners  29  that engage mounts or mounting holes  15  in the beam section  14  and mating holes  33  in the frame end flange (FIG.  2 ). Energy absorbers  19  and  21  can be positioned at the end of the frame and between the end of the frame and the bumper beam. 
     The bulkheads  16  may also be constructed of various structural materials by appropriate methods. While the bulkheads  16  and  16   a  (FIG. 8) are shown as corrugated members with generally flat edges, they may also be fabricated in various alternative configurations according to the preferences or structural requirements of the user or manufacturer, such as the serpentine shape  16   b  employed in the center of the beam in FIG.  9 . Further, specific considerations of a particular installation may influence the configuration and fabrication of the bulkheads  16 , including the number and spacing of the bulkheads, for example. One of numerous variations of the use of interconnecting bulkheads or tie plates between the channel members  12  and  14  may include the use of plates  18  between the respective flanges  22  and  24  of the channel members, for example (FIG.  6 ). 
     A first alternative embodiment of a bumper beam of the invention is also generally shown in the drawing figures and identified with the reference number  110  (FIGS.  11 - 17 ). The bumper beam  110  also includes opposing first and second channel members  112  and  114 , respectively, and at least one tie plate  116  that interconnects the channel members (FIGS.  11 - 17 ). 
     As with the channel members  12  and  14 , the channel members  112  and  114  are also preferably aligned with one another, being generally parallel with one another and centered relative to one another. The channel members  112  and  114  may also be configured or constructed similarly or distinctly, as discussed above regarding the channel members  12  and  14 . 
     The first and second channel members  112  and  114 , respectively, are also simple open sided U-shaped channel members with two legs or flanges  122  and  124  extending in generally the same direction from opposing edges of a bight or web portion  126  (FIG.  14 ). The second channel member  114  will commonly be generally linear, while the first channel member  112  will commonly be generally arched, with the corresponding ends of the channel members meeting (FIGS.  11 - 12 ). The channel members  112  and  114  are interconnected by the bulkheads or tie plates  116  (FIGS. 11,  12 , and  14 ). A noted difference of the use of the plates  116  in the beam  110 , as compared to the plates  16  in the beam  10 , is that the channel member  114  may be truncated to extend along only a central portion of the beam  110 , while the plates  116  continue outward to the ends of the channel member  112 . 
     The plates  116  may also be constructed with various configurations of various structural materials by appropriate methods for the configuration and material selected. As shown, the plates  116  are what may commonly be known as flange plates, having a web  132  and a flange  134  (FIG.  15 ). The tie plates  116  have a forward or leading edge  136  that preferably corresponds to and follows any curve or other contour of the front or first channel member  112 . The tie plates  116  also have an opposing back or trailing edge, which is defined by the plate flange  134 . The trailing edge will preferably correspond to the back or second channel member  114 . Thus, the tie plate trailing edge will commonly be substantially straight, which is easily manufactured, but may alternatively incorporate a curve or other contour. 
     As noted above, the channel member  114  may be truncated to extend along only a central portion of the beam  110 , while the plates  116  continue outward to the ends of the channel member  112 . Conversely, the second channel member  114  may extend fully along the length of the beam  110  or may comprise a series of channel member segments that are disposed along the beam length. In consideration of weight considerations, lightening holes  140  may be used in the web  126  of the second channel member  114  and may also be used in the webs  132  of the tie plates  116  and the web  126  of the first channel member  112 , as permitted by desired structural performance criteria. 
     It will be understood by one having ordinary skill in the art and by those who practice the invention, that various modifications and improvements may be made without departing from the spirit of the disclosed concept. Various relational terms, including left, right, front, back, top, and bottom, for example, are used in the detailed description of the invention and in the claims only to convey relative positioning of various elements of the claimed invention. The scope of protection afforded is to be determined by the claims and by the breadth of interpretation allowed by law.