Lightweight constructional element with external ribbing

Abstract

A lightweight constructional element (100) is disclosed. The lightweight constructional element (100) comprises: (a) a shell-shaped basic body or shell (1), e.g., fabricated from metal, having interior (20) and exterior (23) surfaces, the interior surfaces (23) of the basic body define an interior space (26); and (b) reinforcing ribs (2a, 2b) of plastics material, preferably thermoplastic material, which are fixedly attached to the exterior surface (23) of basic body (1). The reinforcing ribs are fixedly attached to the exterior surface of said basic body by means of discrete attachment points {which may include, for example, apertures (3a), slots (3f), beads (3b) and/or protrusions (3c)}. Articles of manufacture that may include the lightweight constructional element include, for example, structural components of motor vehicles (e.g., a cross car beam) and aircraft, and a structural component having a channel for receiving at least one of a cable and a gas.

Description

CROSS REFERENCE TO RELATED PATENT APPLICATION

[0001] The present patent application claims the right of priority under 35 U.S.C. §119 (a)-(d) of German Patent Application No. 102 08 953.1, filed Feb. 28, 2002.

FIELD OF THE INVENTION

[0002] The invention relates to a lightweight constructional element comprising a shell-shaped basic body, in particular of metal, having reinforcing ribs of plastics material, in particular of thermoplastic plastics material, which are permanently fixed to the basic body.

BACKGROUND OF THE INVENTION

[0003] Stiff, high-strength lightweight structural elements with internal ribbing already exist in what is commonly referred to as “hybrid technology” (generally, a technology involving the combination of metal inserts with thermoplastic plastics material). For reasons of space constraints, however, such structures do not meet the requirements associated with integration of additional components and application (e.g., conduits for wiring and air transport, and other channels, within the interior of the basic body).

[0004] Previously, instrument panel supports or so-called cross-car beams or cross-members in motor vehicles have been produced from steel tubing with various welded-on or screwed-on parts. These parts have relatively high weight. Moreover, with these elements the above-mentioned direct molding-on of further constructional elements to the basic body using the injection-molding process is impossible or possible only with difficulty.

[0005] EP 370 342 A1discloses a lightweight constructional element consisting of a shell-shaped profile section with internal supporting ribs consisting of molded-on thermoplastic plastics material. Although this constructional element may be used as a support structure, in particular in the form of plastics-metal composite bodies, its further technical application as a constructional element is typically limited.

[0006] It is an object of the invention to develop a lightweight constructional element which is relatively simple to manufacture and has good physical properties, such as high stiffness and strength. Such a newly developed lightweight constructional element preferably consists of one or optionally a plurality of (shell-shaped) basic bodies. It is desirable that the basic bodies of such newly developed lightweight construction elements must provide channels for wiring or air transport, and further applications. It is further desirable that such newly developed lightweight construction elements have a level of stiffness that is at least comparable to that of prior art structures, such as metal tube cross-car beams.

SUMMARY OF THE INVENTION

[0007] In accordance with the present invention, there is provided a lightweight constructional element (100) comprising:

[0008] (a) a shell-shaped basic body or shell (1), e.g., fabricated from metal, having interior (20) and exterior (23) surfaces, the interior surfaces (23) of said basic body defining an interior space (26); and

[0009] (b) reinforcing ribs (2a, 2b) of plastics material, preferably thermoplastic material, which are fixedly (or permanently) attached to the exterior surface (23) of said basic body (1),

[0010] wherein said reinforcing ribs are fixedly attached to the exterior surface of said basic body by means of discrete attachment points {which may include, for example, apertures (3a), slots (3f), beads (3b) and/or protrusions (3c)}, said reinforcing ribs being one of directly and indirectly fixedly attached to the exterior surface of said basic body.

[0011] The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and accompanying drawings in which preferred embodiments of the invention are illustrated and described.

[0012] Unless otherwise indicated, all numbers or expressions, such as those expressing structural dimensions, quantities of ingredients, etc. used in the specification and claims are understood as modified in all instances by the term “about.”

[0013] As used herein and in the claims, the term “perforation” means a hole of any size or configuration, typically present in the basic body (1) and optionally the flanges (8) of the basic body, and includes, but is not limited to, apertures and/or slots.

[0014] As used herein and in the claims, the term “aperture” means a perforation having substantially similar cross dimensions, and includes, but is not limited to shapes selected from substantially circular, substantially square, and/or substantially triangular.

[0015] As used herein and in the claims, the term “slot” means a perforation that is generally elongated in one dimension relative to the other dimension(s) of the perforation, and includes, but is not limited to, rectangular slots and elliptical slots.

[0016] As used herein and in the claims, and unless otherwise noted, the term “plastics material” means thermoplastic materials (plastics materials that are substantially free of a 3-dimenstional crosslink network) and/or thermoset plastics materials (plastics materials having 3-dimensional crosslink network).

[0017] As used herein and in the claims, the term “directly fixedly attached” with regard to the exterior reinforcing plastic ribs means that the reinforcing ribs are form- and force-closed connected to the basic body by means of apertures or slots.

[0018] As used herein and in the claims, the term “indirectly fixedly attached” with regard to the exterior reinforcing plastic ribs, means that the reinforcing ribs are force-closed connected to the basic body by means of beads or protrusions.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a representative perspective side view of a substantially closed lightweight constructional element (103) according to the present invention, which includes a cover plate (5a);

[0020] FIG. 2 is a representative perspective side view of an open lightweight constructional element (100) according to the present invention, which includes substantially laterally outwardly extending (or doubly angled) reinforcing flanges (8);

[0021] FIG. 3 is a representative section through a closed profile section of substantially closed lightweight constructional element (105) that is similar to that of FIG. 2; and

[0022] FIG. 4 is a representative section through a lightweight constructional element (107) similar to that of FIG. 3 having apertures in the basic body and in the cover plate.

[0023] In FIGS. 1 through 4, like reference numerals designate the same components.

DETAILED DESCRIPTION OF THE INVENTION

[0024] In an embodiment of the present invention, the basic body is fabricated from a material selected from at least one of thermoset plastics material, thermoplastic materials and metal. In a further embodiment, the plastics material of the reinforcing ribs is selected from at least one of thermoset plastics material and thermoplastic materials.

[0025] The connection between the reinforcing ribs and the basic body is preferably effected at or by means of perforations (e.g., apertures and/or slots) through which the plastics material passes and extends beyond the plane of the perforations (e.g., apertures and/or slots).

[0026] Increased or improved stiffness of the constructional element may be obtained in a preferred embodiment of the present invention when the connection between the reinforcing ribs and the basic body is additionally effected by means of at least partially encasing the rim portions of the basic body by means of plastics material. More particularly, in an embodiment of the present invention the basic body of the lightweight constructional element has a shape selected from substantially U-shapes and substantially V-shapes each having two sidewalls (e.g., substantially opposed sidewalls), each sidewall having a rim, and the reinforcing ribs are further fixedly attached to the exterior surface of the basic body by means of plastic material of the ribs at least partially encasing the rims.

[0027] In a preferred embodiment of the present invention, the lightweight constructional element is given still greater stiffness if the basic body has in its rim portion an angled reinforcing flange, in particular a doubly-angled reinforcing flange. More particularly, the basic body of the lightweight constructional element has a shape selected from substantially U-shapes and substantially V-shapes each having two sidewalls (e.g., substantially opposed sidewalls), each sidewall having a substantially laterally outwardly extending flange (e.g., an angled reinforcing flange), and said reinforcing ribs are further fixedly attached to the exterior surface of the basic body by means of the plastic material of the ribs at least partially encasing the flanges.

[0028] These angled rim portions (or laterally outwardly extending flanges) of the basic body can be variously formed (e.g., in accordance with the deep-draw process of the metal part), and their configurations are, for example, primarily determined by the design requirements of the constructional element as a whole.

[0029] The lightweight constructional element is particularly simple to manufacture but also simple to detach (e.g., separate the reinforcing ribs from the basic body or shell) for the purposes of plastics material recycling, if the connection between the reinforcing ribs and the basic body is effected by means of the plastics material molded onto the exterior surfaces of the basic body, e.g., by means of the injection-molding technique, as will be discussed in further detail herein.

[0030] In a particularly preferred embodiment, to further increase the strength of the lightweight constructional element, the exterior surface of the basic body ( in addition to the reinforcing ribs) is encased with plastics material. The exterior encasing plastics material may optionally be continuous with the plastics material of the exterior reinforcing ribs.

[0031] Particularly advantageous with respect to corrosion protection, e.g. of metal inserts, is a preferred lightweight constructional element of the present invention, in which the interior surfaces of the basic body are at least partially encased in plastics material. The interior encasing plastics material may optionally be continuous with the plastics material of the exterior reinforcing ribs that extends through perforations in the basic body into the interior space of the basic body, and thereby serving to further fixedly attach the exterior reinforcing ribs to the exterior surface of the basic body.

[0032] The spatial form of the shell of the lightweight constructional element can be freely selected, depending on the application. A preferred constructional form of the lightweight constructional element is characterized in that the the basic body has a shape is selected from substantially U-shapes and/or substantially V-shapes (relative to the profile section of the basic body).

[0033] The advantage of the basic body of the present invention, as compared to closed box-section basic bodies, lies in the greater simplicity of its manufacture, e.g., by means of the extrusion process.

[0034] To form wiring or air conduits the shell-shaped basic body may optionally be closed with a cover plate. A lightweight constructional element is therefore preferred which is characterized in that at least one additional cover plate enclosing the interior space of the basic body at least partially, and in particular completely, is attached across (or over) the interior space of the basic body. In an embodiment of the present invention, the basic body has a shape selected from substantially U-shapes and substantially V-shapes each having two sidewalls, each sidewall having a substantially laterally outwardly extending flange, the lightweight constructional element further includes a cover plate, which is fixedly attached to each of the flanges and covers at least a portion of the interior space of the basic body.

[0035] The cover plate can project in any desired manner beyond the side portions (or sidewalls) of the lightweight constructional element. In which case it may then optionally contain further functional elements such as dashboard parts, etc., and can therefore serve as a further design feature.

[0036] In a particularly preferred form of the lightweight constructional element of the present invention, the cover plate is jointly encased by plastics material in the rim portion of the basic body to close the interior space. In an embodiment, the cover plate is fixedly attached to the basic body by means of plastics material encasing each of the flanges and at least a portion of the cover plate that abuts (or is at least superposed over) each of said flanges.

[0037] The stiffness of the constructional element can be further increased if the cover plate is preferably combined with the basic body by means of apertures or slots arranged one above the other, through which the plastics material passes and extends beyond the plane of the apertures or slots. A kind of riveted plastics connection is thereby produced. In an embodiment of the present invention, each of the cover plate and the flanges have a plurality of perforations, each perforation having a plane, at least some of the perforations of the cover plate and flanges are aligned with each other, the aligned perforations form a plurality of aligned perforations each having a plane, the cover plate is fixedly attached to the basic body by means of plastics material extending through and beyond the plain of least some of the aligned perforations. The perforations of the aligned perforations may be selected from apertures and/or slots.

[0038] If an airtight channel is required, the connection between the closure plate and the shell-shaped basic body or the lightweight constructional element may be effected by means of a welded or bonded joint, and/or an additional sealing element such as a rubber seal may be inserted.

[0039] For certain applications (e.g., air conduit, etc.) a preferred lightweight constructional element is advantageous which is characterised in that the attachment point of the cover plate to the basic body is closed in an airtight manner by means of a welded or bonded joint or by means of a sealing agent, in particular a rubber seal. The cover plate, in an embodiment of the present invention, forms an airtight seal over the interior space of the basic body by means of a welded joint, a bonded joint and/or a sealing agent positioned between each of the flanges and at least a portion of the cover plate that is fixedly attached to each of the flanges.

[0040] A preferred form of the lightweight constructional element in which the interior of the basic body has at least one dividing wall, in particular of thermoplastic plastics material, has proved successful in separately accommodating a plurality of conduits.

[0041] Sheet metal, preferably steel or aluminum sheet, diecast metal, in particular aluminum, zinc or magnesium, or fiber-reinforced plastics material or composite material may be used as the preferred material for the basic body and optionally the cover plate of the lightweight constructional element.

[0042] As a preferred material for the reinforcing ribs and optionally the encasement of the lightweight constructional element, a plastics material selected from the series: polycarbonate, polyester, in particular PET or PBT, polyurethane, polystyrene, polyamide, polyalkylene, in particular polypropylene, is used.

[0043] Lightweight, structural and housing elements with high functionality find application in the vehicle industry, in mechanical engineering and the appliances industry, in the electrical industry and in other constructional elements.

[0044] In particular, these elements can be used in the vehicle industry as instrument panel supports or so-called cross-car beams (CCBs).

[0045] If applicable, further constructional elements such as trim or functional parts for the dashboard area can be directly molded on to the exterior areas of the basic body or the ribbing, using the injection-molding process.

[0046] Manufacture of the above-mentioned lightweight structural elements is possible in a reasonable manner with a relatively short production time, especially using the injection-molding process. In a preferred embodiment of the present invention discrete attachment points include a plurality of perforations, a plurality of beads and/or a plurality of protrusions. The reinforcing ribs are preferably fixedly attached to the outer surface of the basic body by means of a process of molding plastics material onto the exterior surface of the basic body, the molded-on plastics material at least one of: (i) extends through at least some of the perforations and into the interior space of the basic body; (ii) fills at least some of the slots; (iii) fills at least some of the beads; and (iv) encases at least partially at least some of the protrusions. The process of molding plastics material onto the exterior surface of the basic body includes: (i) injection-molding (in the case of thermoplastic, materials): (ii) reaction-injection-molding (in the case of thermoset plastics materials, such as 2-pack thermoset or thermosetable polyurethane compositions); and (iii) a combination of injection-molding and reaction-injection-molding (in the case of plastics compositions that include both thermoplastic materials and thermoset plastic materials or components).

[0047] The invention therefore further relates to the application of a lightweight constructional element according to the invention as a structural component or support structure for motor vehicle or aircraft construction, in particular as a support structure with a channel for wiring or gas, particularly preferably with an air channel, and particularly preferably as an instrument panel support or cross-car beam. Articles of manufacture that may include the lightweight constructional element of the present invention include, but are not limited to: a structural component of a motor vehicle; a structural component of an aircraft; and a structural component having a channel for receiving at least one of a cable and a gas. Further articles of manufacture that may include the lightweight constructional element of the present invention include, but are not limited to: an instrument panel support; and a cross-car beam.

[0048] In a particularly preferred embodiment of the present invention, the reinforcing ribs, of the lightweight constructional element, form a continuous unitary structure on the exterior surface of the basic body.

[0049] The invention is described in further detail below, in an exemplary manner, with reference to the drawing figures.

EXAMPLES

Example 1

[0050] A U-shaped profile section (basic body or shell) 1 of sheet steel (thickness 0.8 mm) with angled flanges 8 (in the rim region 29) is provided on its exterior with cruciform ribs 2a of thermoplastic plastics material (e.g., of glass-fiber reinforced PA 6). The ribbing is molded on to the profile section using the injection-molding process, as described previously herein. Disposed across the interior of the profile section 1 is a cover 5a which is permanently fixed to the rim 8 of the profile section 1 by means of a molded rim encasement 4.

[0051] At certain points of its surface the profile section 1 has perforations in the form of apertures 3 through which the thermoplastic material passes. The plastics material here forms a riveted connection 3a similar to that depicted in FIG. 3. The profile section 1 according to FIG. 1 forms part of a heated air conduit.

Example 2

[0052] FIG. 2 represents a profile section 1, similar to that of Example 1, in which the profile section 1 has doubly-angled reinforcing flanges 8. Here the lateral reinforcing ribs 2b are disposed perpendicularly with respect to the extension and flanges of the profile section.

[0053] The ribs 2b are attached at profile section slots 3f by means of thermoplastic material passing through the profile section 1. Here the profile section is formed as an open box section.

Example 3

[0054] In the metal profile section 1 shown in FIG. 3 the internal surfaces 20 are encased by thermoplastic plastics material 9, which can be seen in cross-section. Similarly to that depicted in FIG. 1, the profile section 1 has a cover plate 5a which is attached to the profile section 1 by means of bonding agent 6.

[0055] In place of the bonding agent 6, attachment by a welded edge joint can also be provided (not shown). In case of a welded joint the same material/plastics material may be used for the cover plate as for the adjoining interior encasement.

[0056] The cover plate 5a is manufactured, in this case, from glass-fiber reinforced thermoset material.

[0057] Three variants of attachment points are shown in cross-section in FIG. 3: a simple aperture 3a, a trapezoidal bead 3b, and a hemispherical protrusion 3c.

[0058] The profile section 1 has doubly-angled flanges 8 which are encased in thermoplastic plastics material 4 and, in combination with the attachment points 3a, 3b, 3c, ensure the strength of the composite.

[0059] For further stiffening of the constructional element the cover plates 5a may have reinforcing beads 7 disposed in a longitudinal, transverse or cruciform manner.

Example 4

[0060] In FIG. 4 a metal profile 1 is shown in cross-section, which has external plastic ribbing 2a, 2b, similarly to the profile section according to Example 2. Here again, through the injection-molding process, the thermoplastic material passes through the profile section basic body 1 at the apertures 3a, 3e or the slots 3f and forms attachment points.

[0061] Attached across the interior of the profile section 1 is a metal cover 5b which is seated directly on the metal profile 1 and forms therewith an electrically shielded channel 26. Apertures 3g in the cover 5b are disposed directly above the apertures 3e or slots 3f in the profile section 1 and are riveted by means of the plastics material to the profile section 1.

[0062] In view of the angled flange portion of the basic body in FIG. 3, only longitudinal ribs 2b of plastics material on the side areas of the basic body, according to the direction of deformation, are consequently now possible as reinforcement.

[0063] The profile section also has over its entire exterior surface 23 an outer encasement 10 of the same thermoplastic material as the ribs 2a, 2b. In this case the attachment points 3d, 3e, 3f do not need to be located directly in the area of the ribs 2a, 2b.

[0064] The process of attaching a metal cover plate 5b may be executed directly by the normal injection-molding process of the lightweight constructional element or using the so-called “in-mold-assembly-process”, instead of a conventional joining process (bonding, welding 6).

[0065] Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Claims

1. A lightweight constructional element comprising:

(a) a shell-shaped basic body having interior and exterior surfaces, the interior surfaces of said basic body defining an interior space; and

(b) reinforcing ribs of plastics material which are fixedly attached to the exterior surface of said basic body,

wherein said reinforcing ribs are fixedly attached to the exterior surface of said basic body by means of discrete attachment points, said reinforcing ribs being one of directly and indirectly fixedly attached to the exterior surface of said basic body.

2. The lightweight constructional element of claim 1 wherein said basic body is fabricated from a material selected from at least one of thermoset plastics material, thermoplastic materials and metal.

3. The lightweight constructional element of claim 1 wherein the plastics material of said reinforcing ribs is selected from at least one of thermoset plastics material and thermoplastic materials.

4. The lightweight constructional element of claim 1 wherein said discrete attachment points comprise at least one of: a plurality of perforations; a plurality of beads; and a plurality of protrusions.

5. The lightweight constructional element of claim 1 wherein said basic body has a plurality of perforations each having a plane, said reinforcing ribs are fixedly attached to the exterior surface of said basic body by means of the plastics material of said reinforcing ribs extending through at least some of said perforations, extending beyond the plane of said perforations and into the interior space of said basic body, said perforations being selected from at least one of apertures and slots.

6. The lightweight constructional element of claim 1 wherein said basic body has a shape selected from-substantially U-shapes and substantially V-shapes each having two sidewalls, each sidewall having a rim, said reinforcing ribs are further fixedly attached to the exterior surface of said basic body by means of plastic material of said ribs at least partially encasing said rims.

7. The lightweight constructional element of claim 6 wherein the rim of each sidewall has a substantially laterally outwardly extending flange, and said reinforcing ribs are further fixedly attached to the exterior surface of said basic body by means of plastic material of said ribs at least partially encasing said flanges.

8. The lightweight constructional element of claim 4 wherein said reinforcing ribs are fixedly attached to the outer surface of said basic body by means of a process of molding plastics material onto the exterior surface of said basic body, the molded-on plastics material at least one of: (i) extending through at least some of said perforations and into the interior space of said basic body; (ii) filling at least some of said slots; (iii) filling at least some of said beads; and (iv) encasing at least partially at least some of said protrusions.

9. The lightweight constructional element of claim 1 wherein the exterior surfaces of said basic body are at least partially encased in plastics material.

10. The lightweight constructional element of claim 1 wherein at least a portion of the interior surfaces of said basic body are encased with plastics material.

11. The lightweight constructional element of claim 1 wherein said basic body has a shape selected from substantially U-shapes and substantially V-shapes.

12. The lightweight constructional element of claim 1 wherein said basic body has a shape selected from substantially U-shapes and substantially V-shapes each having two sidewalls, each sidewall having a substantially laterally outwardly extending flange, said lightweight constructional element further comprising a cover plate, said cover plate being fixedly attached to each of said flanges and covering at least a portion of the interior space of said basic body.

13. The lightweight constructional element of claim 12 wherein said cover plate is fixedly attached to said basic body by means of plastics material encasing each of said flanges and at least a portion of said cover plate that abuts each of said flanges.

14. The lightweight constructional element of claim 12 wherein each of said cover plate and said flanges have plurality of perforations, each perforation having a plane, at least some of the perforations of said cover plate and said flanges are aligned with each other, the aligned perforations forming a plurality of aligned perforations each having a plane, said cover plate being fixedly attached to said basic body by means of plastics material extending through and beyond the plain of least some of the aligned perforations, said perforations being selected from at least one of apertures and slots.

15. The lightweight constructional element of claim 12 wherein said cover plate forms an airtight seal over said interior space of said basic body by means of at least one of a welded joint, a bonded joint and a sealing agent positioned between each of said flanges and at least a portion of said cover plate that is fixedly attached to each of said flanges.

16. The lightweight constructional element of claim 1 further comprising at least one dividing wall positioned within the interior space of said basic body.

17. The lightweight constructional element of claim 12 wherein said basic body and said cover plate are each independently fabricated from at least one material selected from the group consisting of sheet metal, diecast metal and fiber-reinforced plastics material.

18. The lightweight constructional element of claim 1 wherein the plastics material of said reinforcing ribs is a thermoplastic material selected from at least one of polycarbonate, polyester, polyurethane, polystyrene, polyamide and polyalkylene.

19. An article of manufacture comprising the lightweight constructional element of claim 1 wherein said article is selected from: a structural component of a motor vehicle; a structural component of an aircraft; and a structural component having a channel for receiving at least one of a cable and a gas.

20. An article of manufacture comprising the lightweight constructional element of claim 1 wherein said article is selected from: an instrument panel support; and a cross-car beam.

21. The lightweight constructional element of claim 1 wherein said reinforcing ribs form a continuous unitary structure on the exterior surface of said basic body.