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  Locally reinforced hollow structural assemblyUSPTO Application #: 20080044609Title: Locally reinforced hollow structural assembly Abstract: A reinforced structural assembly is provided including a hollow structure having a cavity with a hole. A bag is inserted into the cavity and has an end with an opening extending out of the cavity through the hole. A device injects a structural foam into the bag. The bag is closed and the end of the bag is inserted into the cavity. A cap is installed over the hole. The foam expands to fill the cavity but is contained within the bag thereby providing localized reinforcement in the desired area. (end of abstract)
Agent: Carlson, Gaskey & Olds, P.C. - Birmingham, MI, US Inventors: David K. Platner, Jim Trotter, Xinyu Wen USPTO Applicaton #: 20080044609 - Class: 428036500 (USPTO) Related Patent Categories: Stock Material Or Miscellaneous Articles, Hollow Or Container Type Article (e.g., Tube, Vase, Etc.), Polymer Or Resin Containing (i.e., Natural Or Synthetic), Foam Or Porous Material Containing The Patent Description & Claims data below is from USPTO Patent Application 20080044609. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The application is a continuation of U.S. patent application Ser. No. 10/649,975, which was filed Aug. 26, 2003, which claimed priority to U.S. Provisional Application No. 60/430,477, which was filed on Dec. 2, 2002. BACKGROUND OF THE INVENTION [0002] This invention relates to reinforcement of a hollow structure, and more particularly, the invention relates to reinforcing a hollow structure with a material such as a structural foam. [0003] Hollow structural members are used in a variety of vehicle applications. For example, portions of a vehicle body such as A- and B-pillars are formed from thin-walled hollow members. Also, suspension assemblies are incorporating increasingly thinner walls for tubular members such as axles. Utilizing thin walled structural members has the advantage of reducing the cost and weight of the assembly incorporating the structure. [0004] In the case of axles, it is desirable to provide a wall thickness that maximizes bending and torsional stiffness while minimizing the weight. However, the thinner the wall thickness, the more susceptible the structure is to buckling under load. For example, auxiliary hardware such as spring brackets are typically clamped to the hollow axle structure. The wall may buckle under the clamping load or the leaf spring may walk during operation of the suspension assembly. To this end, prior art axle assemblies have added local stiffeners by welding on additional reinforcement plates to increase the stiffness, for example. [0005] For vehicle applications with hollow body structures, such as A- and B-pillars for example, structural foams have been injected into the hollow cavity of the structure to provide localized reinforcement. The structural foam expands to fill the space and hardens to stiffen the area. However, walls must be formed in the hollow structure to contain the foam to the desired area since the structural foam is very costly. This is accomplished by stamping or welding steel walls into the structure to contain the foam. This raises complications in forming the hollow structural member, which can add significant cost when formulating a design to accommodate the walls for containing the structural foam. [0006] Therefore, what is needed is a method and apparatus for providing local reinforcement of a hollow structural member while reducing the cost and design complexity of prior art solutions. SUMMARY OF THE INVENTION AND ADVANTAGES [0007] A reinforced structural assembly includes a hollow structure that defines a cavity that receives a bag. The bag is filled with a material, and the material is expanded to provide a localized reinforcement area within the hollow structure. [0008] In one example, the reinforced structural assembly includes a hollow structure having a cavity with a hole. A bag is inserted into the cavity using a tube. The bag has an end with an opening extending out of the cavity through the hole. A device injects a structural foam, such as a two-part epoxy for example, into the bag. The bag is closed and the end of the bag is inserted into the cavity. A cap is installed over the hole. The foam expands to fill the cavity but is contained within the bag thereby providing localized reinforcement in the desired area. For axles, the cap may include a locating feature for positioning a component such as a leaf spring. [0009] Accordingly, the present invention provides a method and apparatus for providing local reinforcement of a hollow structural member while reducing the cost and design complexity of prior art solutions. BRIEF DESCRIPTION OF THE DRAWINGS [0010] Other advantages of the present invention can be understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: [0011] FIG. 1A depicts a bag being inserted into a cavity of a hollow structure; [0012] FIG. 1B depicts a bag being injected with structural foam; [0013] FIG. 1C depicts the bag filled with a structural foam; [0014] FIG. 1D depicts the bag closed with an end of the bag having an opening inserted into the cavity; [0015] FIG. 1E depicts the hole of the hollow structure closed with a cap; [0016] FIG. 1F depicts the structural foam fully expanded within the cavity; and [0017] FIG. 2 depicts a suspension assembly with a hollow axle having localized reinforcement in the area of the suspension attachment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0018] Referring to FIGS. 1A-1F, a reinforced structural assembly of the present invention is shown at 10. The assembly 10 includes a hollow structure 12 defining a cavity 14 with a hole 15 in the wall of the structure 12 providing access to the cavity 14. A bag 16 is inserted into the cavity 14 through the hole 15 using a tube 17, shown in FIG. 1A. The bag 16 includes an end 18 having an opening 20 extending through the hole 15. For example, the bag 16 may be rolled up and inserted into a cardboard tube and then pushed into the cavity 14. The bag may be made of any suitable material in one example the bag is made of a high temperature thermoplastic that can withstand the exothermic reaction of the expanding foam. Such suitable materials may include a mylar, rubber, or polysulphone. Of course, any number of suitable materials may be used. The bag 16 contains the foam during expansion so that internal walls or baffles are not required in the hollow structure, which are difficult and expensive to design and manufacture. [0019] A device 22 having a nozzle 24 injects a foam 26 into the bag 16 through the opening 20, as is best shown in FIGS. 1A and 1B. The device 22 may be manually or automatically operated. The structural foam filler material could be any suitable material having a high modulus. The foam 26 may be a composite material such as a glue, a filled acetal epoxy, a polyester, or any other suitable material. One such material is available by Henkel under the trade name TEROCORE 1015A and B. TEROCORE is a two component structural foam comprising a high strength expanding two-part epoxy with a 2:1 by volume mixed ratio. The TEROCORE epoxy expands approximately 30% and has a high modulus. TEROCORE is an exothermic material that cures an ambient temperature as the two components are mixed together and cures or hardens 90% within the first thirty minutes from the inside out. TEROCORE is fully cured within 24 hours and is a non-isocyanate material that does not require special ventilation during its use. The epoxy resin portion of TEROCORE has good stability and determines the curing speed. Fillers may be added to the material to improve the mechanical properties, provide sagging resistance, hardness, and determine the compression modules. The curing agent portion of TEROCORE determines the reactivity, adhesion, compression modulus, and shelf life of the material. The expanding agent of TEROCORE dictates the cell structure and reduces the overall weight of the structural foam. [0020] Referring to FIG. 1D, once the structural foam 26 has been injected into the bag 16, the bag is closed. For example, the end 18 may be twisted, shown at 28, and inserted into the cavity 14. The hole 15 may be closed off by inserting a cap 30, as shown in FIG. 1E. The cap 30 further contains the structural foam 26 during expansion and provides an aesthetically pleasing appearance. The structural foam 26 expands into engagement with the interior walls of the cavity 14 while remaining contained in the other directions by the bag 16, as best shown in FIG. 1F. Continue reading... Full patent description for Locally reinforced hollow structural assembly Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Locally reinforced hollow structural assembly patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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