The present invention relates generally to the field of bumpers and bumper assemblies for use with vehicles such as automobiles and the like. More particularly, the present invention relates to materials and methods of manufacturing bumper beams for such bumpers and bumper assemblies.
Bumper assemblies for vehicles such as automobiles and the like typically include a bumper beam that is connected to the frame of the vehicle, an energy absorber coupled to the bumper beam, and an outer fascia that is positioned toward the front of the vehicle. The fascia is typically a part of the exterior of the vehicle, and acts to conceal the underlying bumper beam and energy absorber.
Bumper beams are conventionally formed of a metal such as steel or aluminum, and have a generally hollow tubular cross-section. For example, the cross-section of a bumper beam may have a generally rectangular shape or may have a different shape such as a “B-shaped” cross-section that is manufactured by roll forming and sweeping a sheet of metal such that it obtains a desired cross-sectional shape. Examples of bumper beam cross-sections are illustrated in
It would be advantageous to provide an improved bumper beam and/or a method of manufacturing such an improved bumper beam.
An exemplary embodiment relates to a bumper beam for a vehicle that includes an outer skin formed of a polymeric material and a core provided within the outer skin. At least a portion of the core comprises an expanded material. The bumper beam is configured for coupling to a vehicle and the outer skin and core are configured to resist deformation in a vehicle collision.
Another exemplary embodiment relates to a polymeric bumper beam for use in vehicle applications that includes a shell formed of a reinforced thermoplastic material and an interior portion comprising an expanded foam material. The bumper beam is configured for attachment to a vehicle.
Another exemplary embodiment relates to a vehicle bumper beam that includes a tubular member comprising a polymeric matrix and a reinforcing material provided within the polymeric matrix and a material provided within at least a portion of the tubular member that is configured to provide compressive strength for the bumper beam. The bumper beam is configured for attachment to a vehicle and to an energy absorber for a vehicle bumper system.
Referring to
In contrast to the use of bumper beams that are formed of a generally hollow construction from steel or aluminum, according to an exemplary embodiment as shown in
As shown in
It should be noted that while
The outer shell or skin 16 is formed of a thermoplastic or thermosetting polymeric material. According to an exemplary embodiment, the outer skin 16 includes a polymeric matrix that has a reinforcing material incorporated therein. For example, according to an exemplary embodiment in which the polymeric matrix comprises a polypropylene or nylon based material, a reinforcing material may be provided within the matrix to provide enhanced strength for the outer skin. The sheet can be formed into the outer skin or sections thereof by thermoforming, compression forming, or roll-forming.
Although according to one exemplary embodiment, the sections of the outer skin 16 are formed of a single sheet of polymeric material having a uniform composition throughout, as shown in
Exemplary thicknesses of the sheets that form the outer skin can range from 1-20 mm. According to an exemplary embodiment, the outer skin has a thickness of between approximately 2 and 7 mm. The thickness of the sheets that form the outer skin can also vary depending upon the location and the structural requirements for the outer skin at different locations on the bumper beam.
Any of a variety of reinforcing materials may be utilized according to various other exemplary embodiments for the outer skin. For example, a reinforcing material may be provided as generally continuous and unidirectional strands of materials such as glass, carbon, or nylon fibers that are oriented in any suitable direction (e.g., along the length of the bumper beam) within the polymeric matrix. According to other exemplary embodiments, the fibers may be provided as short strands that are generally randomly oriented within the polymeric matrix. According to still other exemplary embodiments, the reinforcing material may be provided as a mat of reinforcing fibers. It should also be understood that more than one type of reinforcing material may be used (e.g., a mat of glass fibers may be incorporated within the polymeric matrix along with randomly oriented short strands of carbon fibers).
According to a particular exemplary embodiment, glass fibers having an average length greater than 25 mm may be used as a reinforcement material for one or both sections of the outer skin. The relatively long glass fibers incorporated within the thermoplastic sheet is intended to provide a relatively high strength thermoplastic composite skin with superior impact performance as compared to thermosetting composites. According to other exemplary embodiments, glass fibers having a length less than 25 mm may be used in place of or in addition to the long glass fibers (either randomly oriented or in a generally unidirectional arrangement).
The inner core 18 is provided in the form of a foam material such as an expanded polypropylene, polyurethane, polystyrene, or similar materials or derivatives thereof. One advantageous feature of such a construction is that the outer skin 16 provides requisite tensile strength for the bumper beam, while the inner core 18 provides the necessary compressive strength for the bumper beam. The foam may be provided as a preformed component within a mold or may be provided such that the foam is expanded in situ during the molding of the bumper beam.
The core is intended to provide buckling stability for the outer skin, and absorbs energy in localized impacts. A high compressive strength core bonded to the high tensile strength skin provides a very robust bumper beam. The finished bumper beam is intended to provide a relatively low cost, lightweight alternative to conventional metal bumper beams.
The core materials can be any material with a very high ratio of compressive strength to mass. Typical foams would have an average compressive strength of between approximately 0.3 and 1.5 MPa. According to an exemplary embodiment, an 80 gpl foam having a compressive strength of about 1.1 MPa is used.
Referring to
Other methods may also be used to form the bumper beam according to other exemplary embodiments. For example, according to one exemplary embodiment, the bumper beam may be formed in a process 60 in which a foam core is not provided prior to molding the bumper beam, as described with respect to
In a first step 61, a mold is provided for use in forming the bumper beam. A first thermoplastic sheet is provided on one side of the mold and a second thermoplastic sheet is provided opposite of the first sheet in steps 62 and 63. The mold is then closed in a step 64 to join the sheets together to form the outer skin for the bumper beam. A foam precursor is injected into the mold between the first and second thermoplastic sheets in a step 65, after which the foam expands to fill a cavity between the sheets in the mold in a step 66. The mold is opened and the bumper beam is ejected from the mold in a step 67, after which any trimming/deflashing is performed on the bumper beam as may be required.
The composition and structure of this bumper beam permits a variety of design elements to be formed as part of or incorporated into the bumper system, including the insertion of reinforcements, crush cans, mounting brackets, and other components. Various features, such as guides, can also be formed into the outer skin to facilitate assembly of the bumper system. Attachments brackets can be inserted in between the sections of the outer skin and the core piece.
According to an exemplary embodiment shown in
According to another exemplary embodiment shown in
The member 82 is provided to couple the bumper beam 80 to the frame rails 6 of the vehicle, and extends between the frame rails. Fasteners 83 (e.g., bolts, screws, etc.) are provided for coupling the bumper beam and/or the member 82 to the frame rails to secure the bumper beam to the vehicle. As illustrated in
The member 82 is configured to provide additional resistance to bending and crushing of the bumper beam. According to various other exemplary embodiments, other reinforcing members such as plates, beams, angle irons, and other structural members may be coupled to the bumper beam (either within or outside the bumper beam).
Because the bumper beam is formed from a polymeric material, the configuration of the bumper beam may be relatively easily varied according to any of a variety of considerations (in contrast to roll formed bumper beams such as those shown in
Other features may also be incorporated in the design of the bumper beams according to various other exemplary embodiments. For example, a number of solid or hollow members or cores in the form of cylinders 100 (shown in
Honeycomb (or other shaped) cores may also be used in conjunction with a foam material provided within the bumper beam. For example, a foam may be used as the primary core material and with smaller honeycomb sections placed where needed to absorb energy. According to an exemplary embodiment, a typical honeycomb core, such as the one shown in
The size, shape, location and/or configuration of these members may be vary according to various exemplary embodiments. According to other exemplary embodiments, any of a variety of cross-sectional shapes for the members may be employed in the bumper beam to provide the desired rigidity, strength, and formability crashworthiness for the bumper beam (e.g., cross-sectional shapes such as ovals, octagons, squares, triangles, trapezoids, pentagons, and the like may be utilized for the members).
According to one exemplary embodiment, the bumper beam has a relatively uniform cross-sectional shape and composition from end to end. According to other exemplary embodiments, the bumper beam may have a variable cross-sectional shape from end to end. Again, because the process used to form the bumper beam allows for enhanced flexibility as compared to the roll formed bumper beams as shown in
One advantageous feature of the flexibility that may be realized in designing the bumper beam is that features may be integrated within the bumper beam that may eliminate the necessity to have a separate energy absorber coupled to the bumper beam. As shown in
According to an exemplary embodiment, the ends of the bumper beam are open such that the foam material provided as the core is exposed at the ends of the bumper beam. According to other exemplary embodiments, the foam material may be concealed on the ends of the bumper beam by providing caps or covers for the ends of the bumper beam (or by molding the beam in a manner such that the skin material is folded over and joined at the ends of the bumper beam to conceal the internal core materials).
It should be noted that references to relative positions (e.g., “top” and “bottom”) in this description are merely used to identify various elements as are oriented in the FIGURES. It should be recognized that the orientation of particular components may vary greatly depending on the application in which they are used.
For the purpose of this disclosure, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary in nature or moveable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or may be removable or releasable in nature.
It is also important to note that the construction and arrangement of the bumper beam as shown in the various exemplary embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied (e.g., the position of a reinforcing member), and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to other exemplary embodiments. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present inventions as expressed in the appended claims.
This application claims the benefit of U.S. Provisional Patent Application No. 60/834,880 filed Aug. 2, 2006, the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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60834880 | Aug 2006 | US |