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.
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.
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.
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.
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.
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.
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.
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.
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:
Referring to
A device 22 having a nozzle 24 injects a foam 26 into the bag 16 through the opening 20, as is best shown in
Referring to
The reinforced structural assembly 10 may be used in any thin walled hollow structural application in need of localized reinforcement. For example, the present invention may be used to locally reinforce hollow portions of the vehicle body such as A and B pillars. Specific areas of the body may be stiffened enabling thinner walls to be used elsewhere.
The present invention is also suitable for use in suspension assemblies 32, as shown in
The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
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.
Number | Date | Country | |
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60430477 | Dec 2002 | US |
Number | Date | Country | |
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Parent | 10649975 | Aug 2003 | US |
Child | 11877886 | Oct 2007 | US |