WO2001032496A1

WO2001032496A1 - Structural assembly including a retention member and method for forming the assembly

Info

Publication number: WO2001032496A1
Application number: PCT/US2000/029973
Authority: WO
Inventors: John A. Townsend; Mohamad E. M. El-Sayed
Original assignee: Joalto Design, Inc.
Priority date: 1999-10-29
Filing date: 2000-10-30
Publication date: 2001-05-10
Also published as: WO2001032496A8; WO2001032496A9

Abstract

A structural assembly (24) including a retention member is provided that is suitable for use in connection with the frame of a vehicle. The structural assembly includes a first structural member (26c) having a longitudinal length and including at least one flange having a slot (32); a second structural member (26b) having a longitudinal length and including at least one flange having a slot adapted for interconnecting with said first structural member, and a retention member. The second structural member is adapted to traverse and interconnect with the first structural member to form an intersection. The retention member (34) is adapted to generally maintain the interconnection between said first and second structural members. A method for forming the structural assembly in accordance with the principles of the invention is also disclosed.

Description

STRUCTURAL ASSEMBLY INCLUDING A RETENTION MEMBER AND METHOD FOR FORMING THE ASSEMBLY

FIELD OF THE INVENTION

The present invention generally relates to structural assemblies, such as those used in connection with a vehicle chassis or body frame. More particularly, the present invention relates to a structural assembly that includes at least one retention member to generally maintain the interconnection between traversing structural members. The present invention also includes a method for forming such a structural assembly.

BACKGROUND OF THE INVENTION

Modular body structures or assemblies for vehicles that include a plurality of connected structural members, are known in the art. Such assemblies commonly involve the attachment of reinforced members to connectors or separate joints to form a body frame.

With a heightened awareness of functionality and safety, particularly in connection with vehicles, the manner in which a body structure handles various forces and related stress and strain becomes increasingly important. Structural members often transmit tensile, compressive, torsional and bending forces throughout the assembly or frame. Unfortunately, the primary failure points or "stress points" of many such prior art assemblies are often found at the connectors or joints.

Alternatively, the structural components of an assembly can be welded to one another, but welding processes can be cumbersome and require a great deal of equipment and capital investment. Moreover, welding can cause a certain degree of warping to the assembly unless it is performed extremely carefully and welded components are often constructed with less than stringent dimensions and tolerances. Another option is to affix the structural components to one another by means of an attachment, such as a nut-bolt combination. However, in addition to the problems associated with facilitating the connection, the shipping and handling of such pre-connected sub-assemblies is often inefficient and/or undesirable.

There therefore exists a need in industry for a structural assembly that is not dependent upon conventional welding technology and which provides sufficient structural support and crash protection safety. There is a further need for such a structural assembly that can be assembled in the field in a simple, versatile, reliable, and cost-effective manner.

SUMMARY OF THE INVENTION

The present invention recognizes the limitations associated with currently available structural assemblies and the production of such assemblies. The present invention provides an assembly wherein the structural members themselves, as opposed to connectors between such members, transmit or absorb a significant majority of the forces acting upon the assembly. When the structural assembly is comprised of a plurality of interconnected structural members, which are formed in accordance with the present invention, such forces can be transferred and accounted for over a significant portion of the interconnected frame or structural assembly. Further, because the slotted structural members of the present invention may be laser cut to extraordinarily precise dimension, and the dimensions are left relatively undisturbed by energy and heat encountered during subsequent processing, the resulting structural assemblies can be produced to extremely accurate dimensions and tolerances. This is particularly true when compared to conventional weld-formed assemblies.

In accordance with an embodiment of the invention, a structural assembly including a retention member is provided that is suitable for use in connection with the frame of a vehicle. The structural assembly includes a first structural member having a longitudinal length and including at least one flange having a slot; a second structural member having a longitudinal length and including at least one flange having a slot adapted for interconnecting with said first structural member, and a retention member. The second structural member is adapted to traverse and interconnect with the first structural member to form an intersection. The retention member is adapted to generally maintain the interconnection between said first and second structural members. A method for forming the structural assembly in accordance with the principles of the invention is also disclosed.

BRIEF DESCRIPTIONS OF THE DRAWINGS

The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description:

FIG. 1 is a perspective view of an embodiment of first and second structural members shown prior to their engagement and interconnection in accordance with the principles of the present invention. FIG. 2 is perspective view illustrating the engagement and interconnection of the first and second structural members shown in FIG. 1.

FIG. 3 is a perspective assembly view of an embodiment of the present invention that illustrates a structural assembly.

FIG. 4 is a perspective view of the structural assembly of FIG. 3 shown in its assembled form.

FIG. 5 is a perspective assembly view of another embodiment of the present invention.

FIG. 6 is a side elevation view of an embodiment of the present invention that is comprised of several structural assemblies. FIG. 7 is a perspective view of an embodiment of the present invention that includes mating structural assemblies, which form a vehicle frame.

FIGS. 8a through 8e are perspective views of an embodiment of a structural connection that may be used to connect structural assemblies of the present invention.

FIG. 9 is a side elevation illustration of an embodiment of a structural assembly in an automobile door environment that is constructed in accordance with the principles of the present invention. FIG. 10 is a cross sectional illustration of the differences in contact surface associated with generally non-pcrpcndicular traversing structural members when compared with generally perpendicular traversing structural members.

FIG. 1 1 is a perspective view of an embodiment of a structural assembly constructed in accordance with the principles of the present invention, which illustrates an additional feature.

FIG. 12 is a perspective view of an embodiment of a structural assembly, which illustrates an additional feature in several enlarged drawing portions.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, a perspective view of a first structural member 10 and a second structural member 12 is shown. In accordance with the present invention, each structural member 10,12 has a longitudinal length (generally designated by the letter L) and one or more flanges 14 having at least one slot 16. The flanges may, but need not, extend the entire longitudinal length L of the respective structural member. A dimensional width for each of the structural members is illustrated in the figure and is generally designated by the letter W. Slots 16 may, but do not typically extend in a parallel direction to the longitudinal length L of the structural members 10,12. Further, as shown, the slots 16 do not extend through the entire cross section of the structural members 10,12. Generally, the length of the slots 16 (taken in the same direction as the dimensional width W of a particular structural member) is commonly more than 50% of the dimensional width W. It is preferred, when design parameters permit, that mating structural members 10,12 will be interconnected so that the members 10,12 engage one another to the full depth or extent of their respective interconnecting slots 16.

A preferred embodiment shown in FIG. 1 illustrates first and second structural members 10,12 shown prior to their engagement and interconnection. For added clarity, the visible surfaces of members 10,12 are designated Si through S₅ and the visible slots 16 have been additionally designated 16_Λ, 16_B, and 16c. I should be noted that the second structural member 12 includes an additional slot 16_D (not visible in the figure) located on surface S₅. In view of the foregoing designations, FIG. 2 depicts the partial transverse engagement and interconnection of the first and second structural members 10,12 depicted in FIG. 1. As illustrated, slot 16_Λ of the second structural member 12 straddles the lower edges 18 of surface Sj of the first structural member 10. It is important to mention that generally, for proper engagement, the width of the slot 16_Λ must be equal to or greater that the thickness of the surface interconnecting with the slot. Preferably, the width of the slot 16 and the thickness of the interconnecting surface will be quite close to provide a tighter fit and a firmer, more rigid resulting assembly.

In a similar fashion, slots 16_B and 16c of the first structural member 10 receive and interconnect with surfaces S₃ and S₅, respectively. Following the completed engagement and interconnection of the first and second structural members 10,12, surface S of the second structural member 12 is preferably generally parallel to, and may overlap, surface S of the first structural member 10. The region in which the first and second structural members 10,12 engage one another is commonly referred to as an intersection. The intersection may also include all or just portions of the surface areas of segments 20 of one or more of the structural members in close proximity (usually less than several inches) to the overlapping segment of members. Several such segments 20 are shown in FIG. 2.

For improved rigidity and added strength, the structural members 10,12 of the present invention preferably have a generally U-shaped cross section. However the present invention is not limited to structural members having a particular cross sectional design and other shapes and configurations are within the scope of the present invention. By way of example, and without limitation, one or more of the structural members may have an L- shaped, V-shaped, C-shaped, or block/square/rectangular configuration. While the structural members 10,12 can be formed from an almost limitless variety of materials, for engineering structural purposes they are preferably formed from a metal, such as steel or aluminum.

FIG. 3 illustrates an unassembled embodiment of a structural assembly 24 constructed in accordance with the principles of the present invention. The particular structure, which represents an "A" post for a vehicle, may include several structural members 26 and at least one retention member 28. Each of the structural members 26, which includes at least one flange 30 having at least one slot 32, corresponds to an equivalent component in a conventional structure for an "A"-pillar structure of a vehicle. For instance, structural member 26_Λ correspond to an "A" pillar; structural member 26_B corresponds to a rectangular-shaped rear beam; structural member 26c corresponds to a U- shaped top beam; and structural member 26π corresponds to a roof rail. Assuming that the clearances and tolerances between the interconnected structural members are fairly close or "tight," the slotted engagement will generally prevent significant free (non-bending) relative movement between the components with the possible exception of the direction in which the components initially engage one another, i.e., the assembly direction. In the example represented, the direction of assembly between structural members 26_Λ and 26 is the direction that is parallel to, or substantially parallel to, the direction of the engaging slot ES of structural member 26_B, that direction being generally represented by the line designated AD).

Upon engagement, the structural members 26 are generally held or retained in place by the slotted interconnected configuration. However, the structural members are not necessarily held or retained in all directions, and separation along the direction of engagement for the members is possible. Therefore, a retention member 34 is used to ensure that the components of the structural assembly 24 are not free to separate along the individual directions of assembly and interconnection, such as direction AD with respect to structural members 26_A and 26_B.

An important feature of the present invention is its ability to handle various loads and forces. The present invention is particularly favorable for use in connection with high load areas. The transverse interconnection of structural members 26 provides increased surface area of contact between interconnected members, especially when compared to conventional butt-joint welds. As a general rule, the larger the surface area of various members that remains in contact with one another, the more stress and strain relief that is afforded to the structure. Moreover, with the present invention, loads and related forces are accounted for and transferred almost entirely by and through the transverse structural members 26 of the assembly 24, not the individual retention members 34. The retention members are essentially non-load bearing and their primary function is to maintain the interconnection and engagement of structural members 26, not to handle the forces and stresses placed upon the assembly 34 in service. As such, the retention member can typically be formed or constructed of a lightweight material, often providing a significant weight savings for an entire assembly.

In the embodiment illustrated in FIG. 3, the retention member 34 takes the form of a metal plate 36 which is held in place over the intersection of the various structural components by a plurality of rivets 38. However, as further described hereinafter, the retention member is not limited to a single configuration, such as a plate 36, and may include a wide variety of other forms and configurations. FIG. 4 depicts the structural assembly 24 embodied in FIG. 3 shown in its assembled condition with the retention member 34 (in this case a plate 36) secured into position (by rivets 38) over the intersection of structural members 26.

FIG. 5 is illustrative of another embodiment of the present invention. For purposes of a simple comparison, the representative component is once again an "A"-pillar structure. Nevertheless, it should be noted that the present invention has applicability to an almost limitless variety of specific structural configurations and therefore is not limited to the configurations shown. The interconnection of traversing structural members 26 is very similar to the structure depicted in FIGS. 3 and 4. However, in this example, a different retention member 34 is contemplated. As shown, a set of mating molds 40 are designed for, and positioned around, the intersection of engaged members 26 and generally encapsulates all or a portion thereof. As further discussed hereinafter, the molds need not be limited to the encasing the intersections, and can instead be constructed - depending upon practical design constraints - to cover up to and including the entire network of structural members.

The molds 40 are used to form or cast a retention member which substantially covers at least the intersection between structural members 26 to form a composite so as to generally prevent the separation or free movement of the various members 26 in the direction of engagement or otherwise. If desired, and not prohibited by material, weight, cost, or assembly conditions, such a molded or cast retention member 34 can substantially or completely cover or encase all or most of the structural members 26 and create an even more unitary construction. A primary feature of such a composite-retention construction, whether simply over the intersection of structural members or over an entire structural network of members, is the ability of the molding or casting to retain the structure of the assembly without the use of nodes, rivets, welds, clips, pins, or similar joining components. However, such attachment means can also be included in the structural assembly 24, typically underneath the molded retention means, if additional retention is desired. It should be mentioned that in addition to its primary purpose of retaining the position of the structural members 26, the retention member 34 can further serve to protect the underlying components from environmental concerns, for instance, unwanted or excessive moisture. It may also serve to provide additional protection to occupants in case of a collision by providing a crumple zone between the structural members 26 and an impacting object. Finally, retention member 34 may provide at least some additional assembly stiffness, although, as noted above, it is not primarily

The molded retention member 34 is preferably formed by surrounding the structural members 26 in a die or mold with a secondary material that is typically different, lighter weight than the material forming the structural members 26. The associated structural beams are preferably U-shaped or have a more "open" configuration to provide the secondary material with smoother flow channels. The secondary material can be comprised of a plastic, such as a polymer, a metal, such as aluminum or other suitable material. Injection molding and reaction injection molding (RIM) are several conventional processes that can be used to form the retention member 34 of the structural assembly 24. RIM is typically an economical, low-pressure process that broadly covers injection molding in which the compensation of the finished molded article is produced by chemical reaction of injected ingredient materials within a mold. RIM technology is particularly useful in connection with the present invention in that it can produce high quality parts with low tooling investment, and can be used in place of injection molding, vacuum forming, pressure forming, structural foam, sheet metal, or metal casting. FIG. 6 is a side elevation view of an embodiment of the present invention that depicts several structural assemblies 24 connected to form a portion of a vehicle frame 44. In a preferred construction, when design considerations permit, virtually all of the beams or structural members of the assembly/frame will be formed of a lightweight U-scction, joined by the aforementioned slotting technique, and retained in place by a molded retention member. In this manner, an entire assembly can be lightwcightcd without sacrificing function or strength.

It is often desirable to combine one or more assemblies 34 to form larger assemblies. FIG. 7 is a perspective view of an embodiment of the present invention that includes mating portions of a vehicle frame 44 further connected by engageable crossbeams 48 to form an expanded vehicle frame 46. The portions of vehicle frames 44 shown in FIGS. 6 and 7 may be connected using a number of conventional processes that are well known in the art. However, structural members and components which have been covered or overmolded by the secondary material of a retention member 34 may not be easily connected. As such, a preferred and particularly novel method for forming crossbeams 48 between portions of a vehicle frame 46 is illustrated in FIGS. 8a through 8e.

FIG. 8a shows the "exposed" end segments 50 of crossbeams 48. The "exposed" end segments 50 preferably consist of extensions of structural members 26 of an assembly 34 that have purposely been left free from an overcasting or an overmolding of secondary material. Each end segment 50 includes mating slots 52 that are adapted to form a connecting structural crossbeam 48 when engaged with a corresponding member. The arrows shown indicate the manner of engagement of the crossbeams 48 via the mating slots 52. End segments 50 of the crossbeams 48 are then shown engaged in FIG. 8b. FIG. 8c illustrates a wider view of a pair of crossbeams 48 following their engagement and interconnection. In this particular embodiment, a gap G is shown between the thicker portions of the individual crossbeams 48.

As illustrated in FIGS. 8d and 8e, a set of molds 54 can be positioned over and generally encase or enclose the gap G and, if desired, form a mold cavity around further portions of the crossbeams 48. The crossbeam retention molding 56 can then be formed in a similar manner to that previously described in connection with the molded retention member 34 for the associated structural members 26. Generally, the mold cavity will be preformed to match the specific continuous contour of the crossbeams 48 and the resulting material formed within the gap G will make the outer surface of the crossbeam assembly, including molded retention molding, appear to be fairly continuous and unitary.

Another alternative to the foregoing technique is to provide mating crossbeams 48 in which one crossbeam 48 includes an exposed protruding male member and the other crossbeam includes a mating female receptacle that is adapted to receive the protruding member. Upon engagement and interconnection of the mated crossbeams, a molding as described herein can be applied over all or a portion of the crossbeams, as desired.

FIG. 9 represents another embodiment of the present invention wherein the structural assembly is shown in an automobile door environment. The traversing configuration of the structural assembly, such as that illustrated, has been found to provide a surprising level of structural strength and soundness when compared to various conventional door constructions. FIG. 10 shows a basic visual comparison of the cross sectional contact surface lengths CS associated with generally perpendicular (FIG. 10(a)) and generally non-perpendicular structural members (FIG. 10(b)) which have approximately the same dimensional widths. It has been found that the increased contact surface length (and hence area) associated with the generally non-perpendicular structure can provide a notably improved structural function.

FIG. 1 1 illustrates an embodiment of a structural assembly of the type shown in FIG. 9 which depicts the entire structural members encased in a molded retention member. If desired, the structural assembly 34 may also include one or more additional structural members 58 to provide additional strength and rigidity to the structural assembly 34.

FIG. 12 is a perspective view of an embodiment of a structural assembly, wherein additional features are utilized in connection with the structural assembly to further integrate the assembly into the frame, thereby transferring more of the forces and loads throughout more of the frame. Protrusions 60 that can be included as part of the structural assembly 34 can be positioned to interconnect or mate with receptacles 62 on the frame of a structure 66.

A preferred method for forming a structural assembly in accordance with the present invention includes the steps of: (a) providing a first structural member having a longitudinal length and including at least one flange having a slot; (b) providing a second structural member having a longitudinal length and including at least one flange having a slot adapted for interconnecting with said first structural member, said second structural member being adapted to traverse and interconnect with said first structural member to form an intersection; (c) traversing said first structural member and said second structural member and interconnecting said first and second structural members using at least one slot; and (d) providing a retention member, wherein said retention member maintains the interconnection between said first and second structural members. If desired, the retention member may be comprised of a secondary material that can be molded or cast around substantially an entire network of interconnected structural members.

Although certain preferred embodiments of the present invention have been described, the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention. A person of ordinary skill in the art will realize that certain modifications and variations will come within the teachings of this invention and that such variations and modifications are within its spirit and the scope as defined by the claims.

Claims

CLAIMSWhat is claimed is:

1. A structural assembly suitable for use in connection with the frame of a vehicle, said structural assembly including:

a first structural member having a longitudinal length and including at least one flange having a slot; a second structural member having a longitudinal length and including at least one flange having a slot adapted for interconnecting with said first structural member, said second structural member being adapted to traverse and interconnect with said first structural member to form an intersection; and a retention member, wherein said retention member maintains the interconnection between said first and second structural members.

2. A structural assembly as recited in claim 1 , wherein said retention member includes a secondary material, said secondary material being different than the material used to substantially form said first and second structural members.

3. A structural assembly as recited in claim 2, wherein said secondary material is comprised of a metal.

4. A structural assembly as recited in claim 3, wherein said metal is cast to substantially surround said intersection.

5. A structural assembly as recited in claim 2, wherein said secondary material is comprised of a plastic.

6. A structural assembly as recited in claim 5, wherein said plastic is molded to substantially surround said intersection.

7. A structural assembly as recited in claim 2, wherein said retention member includes at least one plate.

8. A structural assembly as recited in claim 7, wherein said plate is comprised of a metal.

9. A structural assembly as recited in claim 7, wherein said plate is attached to said first and second structural members.

10. A structural assembly as recited in claim 9, wherein said plate substantially covers one side of said intersection.

11. A structural assembly as recited in claim 9, wherein said plate is attached to said first and second structural members by a means of attachment selected from at least on of the following: a weld, a rivet, a bolt, a pin, and a clip.

12. A structural assembly as recited in claim 1 , wherein said first structural member is generally u-shaped.

13. A structural assembly as recited in claim 1, wherein said slots of said first and second structural members are non-parallel with respect to the longitudinal lengths of said first and second structural members.

14. A structural assembly as recited in claim 1, wherein said slots of said first and second structural members are substantially peφendicular with respect to the longitudinal lengths of said first and second structural members.

15. A structural assembly as recited in claim 9, wherein a secondary material substantially surrounds said intersection and said plate to provide additional retention.

16. A method for forming a structural assembly suitable for use in connection with the frame of a vehicle, said method including: providing a first structural member having a longitudinal length and including at least one flange having a slot; providing a second structural member having a longitudinal length and including at least one flange having a slot adapted for interconnecting with said first structural member, said second structural member being adapted to traverse and interconnect with said first structural member to form an intersection; traversing said first structural member and said second structural member and interconnecting said first and second structural members using at least one slot; and providing a retention member, wherein said retention member maintains the interconnection between said first and second structural members.