VEHICLE SPACE FRAME AND A METHOD FOR MANUFACTURING OF VEHICLE SPACE FRAME PARTS

Abstract: A vehicle space frame comprising load bearing longitudinal structural members (2) formed from an integral extruded multicavity shape being split, reshaped and aligned to secondary complementary shaped members (8) is provided. A new method of joining the structural members is based on longitudinal internesting of complementary shaped outer surfaces of the members forming the supportive structure of the space frame.

Description: Veh icle space frame and a method for manufacturing of vehicle space frame parts. The present invention relates to a vehicle body structure, and more particularly to a load-bearing space frame, and to a method of manufacturing of such. A space frame for a motor vehicle, comprising a plurality of elongated metal structural members having axially uniform cross-sections joined together by a plurality of intercon¬ necting metal castings, is known from the prior art, and disclosed e.g. in U.S. Patent No. 4,735,355. The special designed castings, having a saddle portion with a contour matching a portion of the cross-section of the structural member, ensure joint of two or several structural members at a given angle. Furthermore, the saddle portion and tubular portion of the castings are provided with outer peripheral edges lying along the outer surface of the structural members, where a welded bead is deposited along these edges in order to reinforce the joint areas. U.S. patent No. 4,355,844 discloses another load-bearing structure for a motor vehicle based on tubular members (girders) joined together by connectors composed of shell elements of thin sheet metal, provided with longitudinal flanges having a plurality of tubular connection stubs. Another construction of the vehicle space frame is disclosed in European Patent Application No. 0146716. The shown frame comprises hollow shapes extruded from light metal represent¬ ing the elongated structural members," connectors of differ¬ ent shapes (configurations) adapted to the shape of the structural members and optionally provided with protruding/- recessing parts in order to incorporate other parts of the vehicle body and finally plate (blanket) parts of different materials (light metals, steel, plastic) to complete the frame structure. All the disclosed space frames are assembled from a large number of individually designed and dimensioned parts and members. The obvious disadvantages of such space frames are too many joints, the necessity to provide costly, specially made connectors and secondary use of reinforcing means in order to achieve satisfactory stiffness and strength of the frame. All these factors adversely affect the vehicle weight, the assembling " costs of the space frame as well as the frames' ability to absorb certain amounts of energy for attaining predictable collision performance. It is therefore an object of the present invention to pro¬ vide an automobile space frame which is simple in construc¬ tion, light in weight, has a few joints generally and no joints situated in critical frame areas and at the same time providing improved collision strength of the construction. Another object of the present invention is to provide a manufacturing method based on simple assembling of special designed load-bearing structural members with no need for specially designed connectors or supplementary reinforcement means. Still another object is to provide a frame assembled from extruded light metal hollow shapes cut and formed to requ¬ ired lengths and configurations from substantially endless stock. According to the present invention the above and other ob¬ jects can be accomplished, in a preferred embodiment, by provision of a vehicle space frame, the supportive structure of which comprises load-bearing structural members and secondary complementary shaped structural members where the load-bearing members include an integral multicavity shape being longitudinally split at its ends and reshaped to form several integrated structural parts of the supportive struc¬ ture. In a particularly advantageous embodiment of the invention the multicavity shape is longitudinally split from both ends into two individual sections, the upper sections being up¬ wardly bent to form a part of the front and rear pillar, respectively, and the lower sections being reshaped to a stepped configuration of the space frame side structure. In a further embodiment of the invention the multicavity shape is also provided with a laterally extending and longitudinally running protrusion being partially removed from the shape and perpendicularly bent to form an inter¬ connecting cross-structural member of the space frame. In contrast to known space frame constructions there is no need for specially designed connectors having interfitting configurations or welding operations for assembling of in¬ dividual structural members. The individual reshaped sec¬ tions of the multicavity shape are simply aligned to the secondary complementary shaped members being internested in the correspondingly shaped outer surfaces of the shape sec¬ tions. The above and other objects and features of the present invention will become more apparent from the following detailed description of preferred embodiment(s) referring to the accompanying drawings. Figs. 1-3, where: Fig. 1 is a fragmentary perspective view of a space frame in accordance with the pre¬ ferred embodiment of the present inven¬ tion. Figs, la, lb and lc are enlarged vertical cross-sectional views of forward brace rear pillar of the space frame and the integral load- bearing structural member, respectively, Fig. 2 is a fragmentary perspective view of a space frame illustrating a detail of an additional structure feature, Fig. 3 is a fragmentary perspective view of another embodiment of a space frame, Fig. 3a is an enlarged vertical cross-sectional view of a load bearing structural member. Referring to the drawings, particularly to Fig. 1, the vehicle space frame 1 shown therein in a fragmentary, par¬ ticularly broken perspective ' view includes load-bearing structural members 2 and a complementary structural member 8 as the only standard members composing a core of the space frame. The load-bearing member 2 is of a closed cross-sec¬ tion provided as an integrally extruded multicavity shape comprising parts or sections 21,22,23 having three indi¬ vidual and vertically arranged voids and one laterally ex¬ tending flange of a closed cross-section 24. The upper part of the multicavity shape comprising the top section 21 is partially removed from the bottom part/sec¬ tion 23 by splitting longitudinally the central straight section 22 e.g. by cutting and is subsequently bent essen¬ tially vertically or at a predeterminated angle to form a part of the front 4 and a rear 3 pillar of the frame, res¬ pectively. Secondary complementary shaped structural members 8 are aligned and joined by any conventional means (not shown on the figures) to the resulting vertically bent sec¬ tions and the remaining forward and backward running sec¬ tions, formed by the remaining bottom part 23 of the multi¬ cavity shape thus - ■ bridging" the split multicavity shape and forming a required stepped configuration of the side vehicle body structure. Details of the joints are illustrated in Fig. la, Fig. lb and Fig. lc showing in cross-sectional view the resulting rear brace 5 and the forward pillar 4 and the central in¬ tegral straight section of the multicavity shape 2 from the Fig. 1, respectively. The front pillar 4 and the rear pillar 3 are parts of framework for the car door. The joints between the secondary complementary shaped structure members 8 and the pillars formed by the reshaped sections 21,23 of the multicavity shape are accomplished by longitudinal in— ternesting of the parts (members) . The secondary members 8 have a simple rectangular outer shape which fit into a complementary cup-shaped surface of the sections 21,23 where two longitudinally running protrud¬ ing flanges forming the cup-like nesting configuration of the sections 21,23 are provided by the above described longitudinally cutting of the multicavity shape. The result¬ ing joints, due to their position in the vicinity of the neutral axis (center) of the thereby formed doubled section, will be exposed only to minor stresses compared to the pre¬ viously known frame designs. Fig. 2 shows a detail of a tripple joint between a front pillar 4, front brace 6 and a transverse girder 7 com¬ pletely eliminating use of specially made connectors. The straight section 22 of the multicavity shape is simply split and bent into the upwardly extending top section 21 and backward running bottom section 23, the sections being joined to the secondary member 8 by means of the above des¬ cribed nested joints. The perpendicularly extending tran¬ sverse girder 7 is formed by partly removed and bent flange 24 of the multicavity shape. Fig. 3 shows another embodiment of the space frame according to the present invention. In this case instead of one inte¬ grally extruded multicavity shape two separate hollow shapes 21,23 provided with longitudinally extending protruding flanges to accomodate secondary complementary shaped members 8 are applied to form in a similar matter the load bearing member 2. The bottom shape 21 is also provided with a later- ally extending flange 24 as seen in Fig. 3a illustrating an enlarged vertical sectional view of a straight section of the joined shapes 21,23 forming the load bearing member 2. The new way of forming and joining the individual structural members of the frame according to the present ' invention obviously reduces the number of parts applied and eliminates the necessity of applying welded connections or special connectors designed to support the joints situated in cri¬ tical areas of the frame. Thus a maximal strength and op¬ timal weight of the structure is achieved in the most load- exposed area between the front and rear pillars of the frame. The structural members may be further secured to each other by any of the known and currently used fastening methods, e.g. by bonding/riveting, welding or by other mechanical means. Other advantages inherent in the structural members of the present invention being provided as extruded hollow shapes made of light metal, e.g. aluminium and its alloys reside in the fact that the members may be easily adapted to serve additional purposes as well. For example the shapes can be extruded with integral brackets or flanges to facili¬ tate mounting of other components of the frame space.

Claims: AMENDED CLAIMS [received by the International Bureau on 5 February 1990 (05.02.90); original claims 1-7 replaced by amended claims 1-7 ( 3 pages )] 1. A method for manufacturing of vehicle space frame parts comprising longitudinally extending structural members (2) c h a r a c t e r i z e d b y steps of providing an integrally extruded multicavity shape (22) and several secondary members (8) , partially splitting of the multicavity shape at least from one end to provide several longitudin¬ ally extending individual sections (21,23) of pre- determinated length, bending of thus provided individual sections (21,23) in a predeterminated angle and their align¬ ing to the secondary complementary shaped members (8) forming structural parts of the vehicle frame, and finally fastening of the assembled members (8) by conventional joining means. 2. A manufacturing method according to claim 1, c h a r a c t e r i z e d i n t h a t the formed structural parts of the vehicle space frame are front and rear pillars (3,4) and front and rear braces (5,6). 3. A manufacturing method according to claim 2, c h a r a c t e r i z e d i n t h a t all the structural members of the frame are ex¬ truded in aluminium or aluminium alloys. 4. A load-bearing structural member, c h a r a c t e r i z e d i n t h a t the structural member (2) includes a straight section of an extruded shape (22) being at least from one end longitudinally split into two or more individual sec¬ tions (21,23) and where at least one of the sections being integral part of the structural member (2) is reshaped extending at a predeterminated angle to form an additional structural part of a supportive space frame. 5. A load bearing structural member according to claim.4, c h a r a c t e r i z e d i n t h a t the structural member (2) is integrally provided with one or more laterally extending and longitudinally running flanges (24) . 6. A vehicle space frame (1) comprising longi¬ tudinally extending load-bearing structural members (2) , c h a r a c t e r i z e d i n t h a t the load-bearing structural members (2) comprise an integrally extruded multicavity shape being at least from one end longitudinally split into two or more sections, and where the individual sections (21,23) as integral parts of the multi¬ cavity shape are extending at predeterminated angles forming alone or 'aligned and connected to secondary complementary shaped members (8) by means of longitudinally internested joints structural parts of the frame (3,4,5,6). 7. Vehicle space frame according to claim 6, c h a r a c t e r i z e d i n t h a t the multicavity shape is provided with a laterally extending flange (24) forming at least one perpendicularly extending transverse girder (7).

Inventors: CLAUSEN EDVIN LIST, CLAUSEN, EDVIN, LIST
Applicants: NORSK HYDRO AS, NORSK HYDRO A.S
Application year: 1989
Main classification: B62D21
IPC codes: B62D21, B62D29, B62D65