Reinforced structural member and method for its manufacture

Abstract

A structural member for the body of a motor vehicle includes a generally elongated support member which at least partially encloses an interior volume, and a reinforcing insert which is disposed in the interior volume. The reinforcing insert extends along at least a portion of the length of the support member, and has a cross section which defines a closed perimeter that encloses an area. The insert member may be configured so as to control its deformation characteristics thereby providing a structural member which efficiently and safely absorbs kinetic energy in a crash.

Description

FIELD OF THE INVENTION

This invention relates generally to reinforced structures. More particularly, the invention relates to reinforced structures used in motor vehicles. In particular, the invention relates to lightweight reinforced structures which can be used as support pillars, frame members and the like for motor vehicles.

BACKGROUND OF THE INVENTION

Many motor vehicles have a passenger compartment or cargo space which is defined and supported by a framework comprised of a plurality of pillars or other such support members. The support members provide structural integrity to the body of the motor vehicle and serve to protect the occupants or cargo in the event of a crash. In some instances, the support members are configured so as to deform in a controlled manner and thereby absorb kinetic energy in the event of a crash.

Pillars comprising the support framework of a motor vehicle are generally configured as hollow steel bodies. Preferably, the support members combine high strength and low weight. Also, the pillars should be low in cost with regard to both materials and their process for fabrication. Ideally, any such support structure should also be amenable to being manufactured by high speed forming processes such as roll forming, cold stamping and the like.

In early prior art, pillar structures for motor vehicles were typically comprised of simple, hollow, tubular members. Eventually various reinforcing members were included in such structures. In some instances, reinforcing members are disposed on the outside of a hollow pillar, and one such structure is shown in U.S. Pat. No. 5,833,303. In other instances, reinforcing members were disposed, at least partially, internally of pillars and other structural members. Some such reinforced structures are shown in U.S. Pat. Nos. 6,341,467; 3,779,595 and 6,883,858.

The motor vehicle industry is directed toward increasing safety and fuel efficiency of vehicles while keeping costs at a minimum. Hence, there are concurrent needs for decreasing the weight and increasing the strength of the passenger and/or cargo compartments of motor vehicles. Toward that end, the industry is seeking structural components for motor vehicles which combine light weight and high strength; furthermore, such components should be capable of having their deformation characteristics tuned or controlled so as to maximize the absorption of kinetic energy while maintaining sufficient integrity to prevent injuries to passengers or damage to cargo in the event of a crash. As will be explained in detail hereinbelow, the present invention is directed to reinforced structural members which may be incorporated into bodies of motor vehicles. The structural members of the present invention are light in weight, inexpensive to fabricate, and can be configured to provide controlled deformation properties. These and other advantages of the invention will be apparent from the drawings, discussion and description which follow.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed herein is a structural member of the type which may comprise a support member for the body of a motor vehicle. The structural member comprises a generally elongated pillar or other such support member which at least partially encloses an interior volume, and a reinforcing insert which is disposed within the interior volume and which extends along at least a portion of the length of the support member. The reinforcing insert has a cross section which defines a closed perimeter that encloses an area. In some instances, the reinforcing insert is bonded to the interior surface of the support member, such as by means of an adhesive or mechanical interconnection. In particular embodiments, the reinforcing insert has a cross section which defines two spaced-apart portions which are joined together by a connecting portion. In specific configurations of this embodiment, the spaced-apart portions each comprise a lobe, each lobe having a cross section which defines a perimeter that encloses a separate, respective area. In some instances, the connecting portion may also have a perimeter which defines and encloses a respective area; while in other instances, the connecting portion may be otherwise configured.

In some instances, the support member and/or the reinforcing insert may be made of steel.

Also disclosed herein is a method for making the structural member, as well as the use of the structural member in a motor vehicle body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, perspective view of one embodiment of structural member of the present invention;

FIGS. 2-5 are cross-sectional views of other embodiments of reinforcing inserts which may be utilized in the practice of the present invention;

FIG. 6 is a cross-sectional view of another reinforcing insert of the present invention, inserted into a support member; and

FIG. 7 is a cross-sectional view of the insert of FIG. 6, which is shown disposed in another configuration of support member.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to structural members which may be used for the fabrication of high strength, lightweight frameworks and other support structures. The present invention has particular utility in a support member for the body of a motor vehicle, and will be explained with particular reference to that utility. However, it is to be understood that the present invention may be employed in connection with other structures such as static building structures, protective cages, intrusion barriers, and other constructions wherein high strength, light weight, and controlled deformation characteristics are required.

The structural member of the present invention includes a generally elongated support member which at least partially encloses an interior volume. As such, the support member's structure may comprise a hollow tubular type of member formed from a single body of material or from plural bodies joined together. In other instances, the support member may be partially open, and as such may have a C-shaped profile. The reinforcing insert is disposed in the interior of the pillar so as to extend along at least a portion of its length. In some instances, the reinforcing insert will extend along the entire length of the pillar, and in other instances it may extend along only a portion of the length of the pillar, while in yet other instances a plurality of separate insert members may be disposed in a support member. The reinforcing insert has a cross-sectional profile which defines at least one closed perimeter bounding an area. As will be explained in detail hereinbelow, in some instances, the insert may bound a plurality of internal areas. The insert increases the strength of the support member, particularly with regard to side loading and/or buckling. The cross-sectional profile of the insert may be controlled so as to control the deformation characteristics of the structural member in which it is incorporated.

Various configurations and embodiments of the present invention may be implemented. Referring now to FIG. 1, there is shown one embodiment of structural member 10 configured in accord with the present invention. The structural member 10 of FIG. 1 comprises a support member 12 which is configured as a hollow, pillar member which encloses an interior volume. As was explained hereinabove, in other embodiments, the support member may only partially enclose an interior volume. The member 12 in this embodiment is comprised of two separate hat-shaped portions 14, 16 which are joined together along their edges so as to form a pair of flanges 18, 20. The two portions 14, 16 may be joined together by welding, adhesives, or by mechanical means such as rivets, toggles, piercings, tabs or the like. In some instances, the support member may be fabricated from a single piece of material folded back onto itself or from a tube. The support member, in particular instances, is fabricated from a metal such as sheet steel, and may be manufactured by conventional forming processes such as hot stamping, cold stamping, roll forming, drawing, pressing or the like. In other instances, the support member may be fabricated from polymeric materials or composites utilizing well-known techniques including casting, molding extrusion and the like.

Disposed within the interior volume of the support member 12 is a reinforcing insert 22. In the FIG. 1 embodiment, the reinforcing insert 22 includes a first lobe portion 24 and a second lobe portion 26 joined together by a connecting portion 28. In the illustrated embodiment, the two lobe portions 24, 26 each have a cross section of trapezoidal configuration which encloses a respective interior volume. It has been found, in particular embodiments of the present invention, that a trapezoidal cross section is advantageously employed in at least portions of reinforcing inserts of the present invention. An insert with a trapezoidal portion provides high strength and good resistance to crushing when subjected to a side impact. This is in contrast to square-sided structures which tend to collapse in a failure mode akin to the collapse of a side-loaded matchbox; hence, this failure mode is referred to in the art as “matchboxing.”

In the illustrated embodiment, the two lobe portions 24, 26 of the insert 22 are joined together by a connector portion 28 which is a simple straight wall structure. As will be detailed hereinbelow, other configurations of insert may be employed in the practice of the present invention.

As shown herein, a back wall portion 30 of the first lobe 24, and a back wall portion 32 of the second lobe 26 are corrugated. One function of these corrugations is to hold an adhesive material therein. For example, a heat activatable, foamable adhesive may be disposed in the corrugations of the insert 22 of FIG. 1. The recessed portions of the corrugation will allow the insert to be stored, handled and subsequently disposed within the support member 12 without causing unwanted transfer of adhesive; however, when the resulting combination is subsequently heated, as for example during painting or further processing steps, the adhesive will foam, expand, and fill the space between the insert 22 and inner surfaces of the support member 12. The adhesive will assure that the insert remains in place in the support member without shifting or rattling. The feature of the corrugations and/or the adhesive is optional, and it is to be understood that the profiles of the lobes as illustrated in FIG. 1 are to be considered trapezoidal even though there is some corrugation of the surfaces of the lobes.

Support members such as the pillar shown in FIG. 1 may be fabricated as relatively long members which are subsequently cut to length for use in particular applications, or they may be fabricated to approximate finished dimensions. Also, while the FIG. 1 embodiment shows a generally linearly elongated structural member, it is to be understood that the present invention may be readily adapted to the manufacture of components having a curved or other complex geometry.

The support member may be formed to a finished profile and then have the insert placed therein, for example as by threading it through an open end. Or, the support member may be partially fabricated, the insert disposed therein, and the structure then completed so as to enclose the insert. In specific instances, the insert is fabricated from high strength, relatively thin steel, such as a hardenable steel. Both the support member and insert may be fabricated from relatively thin steel stock which can be bent to radii as low as one thickness of the stock material, so as to crowd the profile mass to the outermost tension and compression sides of the structure. In specific embodiments, the components are made out of a material such as aluminum, steel, or aluminized steel having a strength of over 100 ksi. In specific instances, the thickness of the reinforcing member is between 0.5 mm and 2.0 mm, and in yet other instances, the distribution of material between the first 24 and second 26 lobes is approximately 60% and 40% respectively.

The completed structural member may be subjected to further post-fabrication processing and this can involve shaping operations such as roll forming, sweeping, bending, die forming, cutting, drilling, flattening, crushing and the like which change its shape or profile. Likewise, the individual support member and/or reinforcing insert may be subject to such processing steps prior to assembly. Other operations may comprise heating, quenching, welding, brazing, cutting, piercing and the like. For example, the member may be bent, swept, or twisted to form a component such as bumper bar or side intrusion beam for a motor vehicle. In that regard, the member may be heat treated so as to increase its hardness.

Other configurations of reinforcing insert may be utilized in the present invention. For example, FIG. 2 shows an insert 40 which comprises a body having a closed cross-sectional profile with an upper portion 42, and a lower portion 44 joined by an intermediate portion 46. All of the portions are contiguous so as to bound a single internal space. As in the previous embodiment, surfaces 48, 50 are corrugated; although, it is to be understood that flat surfaces, concave surfaces, convex surfaces or the like may be likewise employed. It will be appreciated that by varying the dimensions L and D of the intermediate portion 46, crushing and bending characteristics of the insert 40 may be adjusted.

FIG. 3 illustrates another embodiment of insert 52. This insert 52 is generally similar to the insert 22 of FIG. 1 insofar as it includes an upper lobe portion 54 and a lower lobe portion 56, both of which have a generally trapezoidal cross section. As in the FIG. 1 embodiment, the two lobe portions 54 and 56 are joined by a connecting portion 58; however, this connecting portion is of an open configuration, and in that regard also bounds an interior space. The open, diamond-shaped configuration of the connecting portion 58 allows for controlled crushing and/or bending of the insert 52. It will be appreciated that this intermediate portion 58 may be otherwise configured; for example, it may comprise a member having a circular cross section as well as otherwise configured polygonal cross sections.

FIG. 4 shows yet another configuration of insert 60 which is configured to have a simple, trapezoidal cross section. As illustrated, this member includes corrugated surfaces 62 and 64; this feature is, as noted above, optional and the surfaces may be otherwise configured.

FIG. 5 shows yet another embodiment of insert 70. This insert 70 is of generally trapezoidal configuration, and in that regard is somewhat similar to the insert 60 of FIG. 4. However, in this embodiment, an upper lobe 72 and a lower lobe 74 are interconnected by two S-shaped portions 76 and 78. Under a predetermined load on the insert 70, the S-shaped portions 76, 78 will plastically deform to allow the sidewalls 80, 82 of the first lobe portion 72 to collapse in a telescoping manner about the sidewalls 84, 86 of the second lobe portion 74. In other versions of this embodiment, further S-shaped portions may be incorporated. Alternatively, corrugations may be disposed to serve a similar function.

In yet other embodiments of insert, selected deformation may be accomplished by cutting, piercing, or otherwise physically interrupting selected wall portions of the insert. Also, it is to be understood that while the foregoing has primarily described the inserts as being fabricated from metals, polymeric materials, including foamed polymeric materials as well as polymer/metal composites, may be employed to form the insert member.

Referring now to FIGS. 6 and 7, there is shown another embodiment of reinforcing insert 90 structured in accord with the principles of the present invention. In both illustrations, the insert 90 has a cross section which defines a closed perimeter that encloses an interior area. The insert 90 further includes projecting flanges 92 and 94. As illustrated, the insert 90 is formed from a single piece of material folded back on itself; although, it is to be understood that it could be fabricated as a two-part member. In the FIG. 6 embodiment, the insert 90 is disposed within a support member 96 which comprises a tubular member having a generally square cross section. As shown in FIG. 6, the insert 90 is placed diagonally in the support member 96 so that the flanges 92 and 94 engage corners thereof. It is to be understood that other embodiments of flanged insert having a different cross-sectional profile, such as a trapezoidal profile, a circular profile and the like, could be similarly disposed.

Referring now to FIG. 7, there is shown the insert 90 as disposed in a support member 98. The support member 98 includes flange portions 100, 102 which engage the flanges 92 and 94 of the insert member 90. In this embodiment, the insert and support member may be secured by tack welds, adhesive, mechanical interlocks, crimps or the like. Yet other configurations of support member and insert may likewise be configured.

Support members of various other configurations may also be employed in the practice of the present invention. Such members may include fully and partially closed structures, curved structures, straight structures, and structures of complex shapes. Also, while the support members are primarily described herein as being made of steel, it is to be understood that support members of other materials including metals and synthetic polymers may be utilized.

In view of the teaching presented herein, still further modifications, variations and embodiments of the present invention will be apparent to those of skill in the art. The foregoing drawings, discussion and description are illustrative of only specific embodiments, and are not meant to be limitations upon the practice of the invention. It is the following claims, including all equivalents, which define the scope of the invention.

Claims

1. A structural member for a body of a motor vehicle, said structural member comprising: a generally elongated support member which at least partially encloses an interior volume; and a reinforcing insert which is disposed within said interior volume and which extends along at least a portion of the length of said support member, said reinforcing insert having a cross section which defines a closed perimeter that encloses an area.

2. The member of claim 1, wherein said cross section of said reinforcing insert is a trapezoidal cross section.

3. The member of claim 1, wherein said reinforcing insert is bonded to an interior surface of said support member.

4. The member of claim 3, wherein said reinforcing insert is adhesively bonded to said interior surface.

5. The member of claim 1, wherein said reinforcing insert has a cross section which defines two spaced-apart portions, said spaced-apart portions being joined together by a connecting portion.

6. The member of claim 5, wherein said spaced-apart portions each comprise a lobe, each lobe having a cross section which defines a perimeter that encloses a separate, respective area.

7. The member of claim 6, wherein at least one of said lobes has a trapezoidal cross section.

8. The member of claim 5, wherein said connecting portion does not have a cross section which defines a perimeter that encloses a respective area.

9. The member of claim 6, wherein said connecting portion has a cross section which defines a perimeter that encloses a separate respective area.

10. The member of claim 1, wherein at least one of said support member and said reinforcing insert are made of steel.

11. The member of claim 1, wherein at least one of said support member and said reinforcing insert are made of roll-formed steel.

12. A method of making a structural member for a body of a motor vehicle, said method comprising the steps of: providing a generally elongated support member which at least partially encloses an interior volume; providing a reinforcing insert having a cross section which defines a closed perimeter that encloses an area; and disposing said reinforcing insert in said interior volume so that said reinforcing insert extends along at least a portion of the length of said support member.

13. The method of claim 12 including the step of carrying out a further processing operation on said support member after said reinforcing insert is disposed therein.

14. The method of claim 13, wherein said further processing operation is selected from the group consisting of: roll forming, sweeping, twisting, bending, die forming, cutting, drilling, flattening, crushing, heating, welding, brazing, quenching, and combinations thereof.

15. The method of claim 12, wherein said reinforcing insert is subjected to a processing operation before being inserted into said support member.

16. The method of claim 12, wherein at least one of said support member and said reinforcing insert are roll formed.

17. The method of claim 12, wherein at least one of said support member and reinforcing insert are made of steel.

18. The method of claim 12, including the further step of bonding said reinforcing insert to said support member.

19. The method of claim 18, wherein said step of bonding comprises adhesively bonding said reinforcing insert to said support member.

20. The method of claim 12, wherein said reinforcing insert has a cross section which defines two spaced-apart lobes, said lobes being joined together by a connecting portion.

21. The method of claim 12, wherein said cross section of said reinforcing insert defines a trapezoidal perimeter.

22. A motor vehicle body which includes the structural member of claim 1.