Auxiliary cross-member structure for supporting elements of a motor-vehicle front suspension

This application claims priority to European Patent Application No. 16188037.2 filed on Sep. 9, 2016, the entire disclosure of which is incorporated herein by reference.

The present invention relates to an auxiliary cross-member structure for supporting elements of a motor-vehicle front suspension, said auxiliary cross-member structure being intended to be connected to a motor-vehicle body, and having a metal sheet frame in the form of a hollow shell, with two opposite end portions, for connection of two respective oscillating arms of the suspension.

FIGS. 10, 11 of the annexed drawings show a general perspective view and a perspective view of a detail of an auxiliary cross-member structure of the type indicated above which has been used in the past for motor-vehicles produced and commercialized by the FCA group, of which the Applicant is a part.

In FIGS. 10, 11 , the auxiliary cross-member structure is generally designated with the reference number 1 . The structure 1 comprises a single metal sheet frame in the form of a hollow shell, which is generally indicated by reference 2 . The main portion of the frame 2 is constituted by two half-shells of metal sheet 3 , 4 which are coupled and welded one to the other. With reference to the mounted condition of the auxiliary structure 1 on the motor-vehicle body, the frame 2 has a cross-member general configuration arranged according to a horizontal general direction which is perpendicular to the longitudinal direction of the motor-vehicle, indicated by line L. Again in FIG. 10 , the arrow A indicates the travel direction of the motor-vehicle.

In the present disclosure and in the claims which follow, both with reference to the prior art here described and to the invention, the terms “upper” and “lower”, “front” and “rear” are referred to the mounted condition of the auxiliary cross-member structure on the motor-vehicle body.

Returning to the known solution illustrated in FIGS. 10, 11 , the upper half-shell 3 and the lower half-shell 4 have coupling flanges 3 A, 4 A along their front and rear edges and partially also along their ends, said coupling flanges 3 A, 4 A being rigidly connected to each other, for example by means of electrical spot welding.

An upright 3 B is welded adjacent to the front side of the cross-member structure at each end of the upper half-shell 3 , said uprights 3 B carrying bushings 5 with vertical axes provided for the engagement of connecting screws for connecting the auxiliary cross-member structure 1 to the motor-vehicle body.

Furthermore, at each end of the auxiliary cross-member structure 1 , the two half-shells 3 , 4 define an upper wall and a lower wall 3 C, 4 C, welded to, and spaced apart from, each other. Adjacent to the rear side of the cross-member structure, the walls 3 C, 4 C have a pair of holes F (the drawings show only the upper hole) aligned with each other along a vertical axis for mounting an elastic bushing with a vertical axis (not shown in the drawings) on which a bush-like end portion B is to be mounted (see FIG. 11 ) of a branch 6 of an oscillating arm T constituting an element of the motor-vehicle front suspension. FIG. 11 shows only a portion of the metal frame of the oscillating arm T. According to the prior art, the external end of the arm T is intended to be pivotally connected to the support of the respective wheel of the motor-vehicle.

Again with reference to FIGS. 10, 11 , in the known solution illustrated therein, the oscillating arm T has a second branch 7 which terminates with an end portion D in the form of a horizontal bush, which is supported by an elastic bushing having a horizontal axis (not shown in the drawings) which is mounted between two vertical flanges 8 protruding from the lower wall 4 C and having holes 9 aligned with each other along a common horizontal axis which is substantially parallel to the longitudinal direction L.

In the rear portion of the cross-member structure 1 , at each end of the cross-member structure 1 , the upper half-shell 3 has a pair of holes 10 aligned along two vertical axes with mating holes (not shown in the drawings) provided on the lower half-shell 4 . The four pairs of aligned holes so defined are used for the engagement of four connection screws, connecting the cross-member structure 1 to the motor-vehicle body.

Therefore, in the above described known solution, six different connection points of the cross-member structure to the motor-vehicle body are provided, namely located on the two uprights 3 B and at four vertical axes along which said holes 10 are aligned.

Again with reference to FIG. 10 , also adjacent to its ends, the cross-member structure 1 comprises two respective pairs of holes 11 for the engagement of screws for connecting a control device (not shown) for steering the front wheels of the motor-vehicle, as well as, at an intermediate area, a bushing 12 having a vertical axis, for engagement of a bracket intended to be connected to the structure of the motor-vehicle powertrain unit by means of an articulated rod, so as to counteract the oscillations of the powertrain unit when in operation. Such elements are herein neither described nor illustrated both because they are conventional, and also because they are not critical for understanding the present invention as described in the following.

Technical Problem

In general, cross-member structures of the type indicated above are used for rationalizing and for automating the assembling operations of the motor-vehicle, since the elements of the front suspension can be preassembled on the auxiliary cross-member structure, so that the entire unit formed by the auxiliary cross-member structure with the elements of the suspension carried thereon can be mounted with a single operation under the motor-vehicle body.

In addition to satisfying this need, naturally the auxiliary cross-member structure has to be able to properly transfer to the motor-vehicle body the forces transmitted by the motor-vehicle front wheels to the cross-member structure during the motor-vehicle travel.

Furthermore, the cross-member structure must have adequate strength characteristics, particularly in relation to torsion deformations.

All the above mentioned requirements must be satisfied by providing a structure which results to be simple and inexpensive to manufacture, at the same time.

Object of the Invention

The object of the present invention is to solve all the aforementioned technical problems more efficiently, in comparison to the known solutions.

In particular, it is an object of the invention to provide an auxiliary cross-member structure which results of low-cost and simple construction, with no prejudice for the required strength characteristics.

A further preferred object of the invention is to provide an auxiliary cross-member structure which results to be significantly lighter with respect to a structure of the prior art having identical strength characteristics.

Yet a further preferred object of the invention is to provide an auxiliary cross-member structure by which the operations for connecting the auxiliary cross-member structure to the motor-vehicle body can be simplified.

In view to achieve one or more of the objects specified above, the present invention has for subject an auxiliary cross-member structure for supporting elements of a motor-vehicle front suspension, said auxiliary cross-member structure being intended to be connected to a motor-vehicle body and having a metal sheet frame in form of a hollow shell with two opposite end portions, for connection of two respective oscillating arms of the suspension.

The auxiliary cross-member structure is characterized in that said hollow frame is defined by a single metal sheet folded on itself, so as to have portions overlapped onto each other and mutually welded.

Preferably, the folding of the metal sheet is performed around folding lines which are all parallel to an ideal folding axis, such as an axis parallel to the longitudinal direction of the cross-member.

Providing the metal frame of the cross-member structure by starting from a single metal sheet simplifies and makes more economical the manufacture of the cross-member structure, mainly because the overlapped portions of the metal sheet can be rigidly connected to each other by means of a number of welding spots significantly lower than the number needed for example in the case of the known solution illustrated in FIGS. 10, 11 of the annexed drawings, in which the metal frame of the cross-member structure is constituted of two separated metal half-shells which are welded to each other both along the front edge and the rear edge of the cross-member, and partially also along the end edges of the cross-member structure.

A further preferred feature of the auxiliary cross-member structure according to the invention is that the auxiliary cross-member structure comprises also an additional filling structure contained within the metal sheet hollow frame and rigidly connected thereto. In the preferred embodiment, the aforementioned additional filling structure is at least partially constituted of synthetic material or composite material incorporating reinforcing fibres. Such a structure can be for example in form of a honeycomb panel, or may have a lattice configuration, or may also be in the form of a panel with a sandwich structure, including panels of plastic material and panels of synthetic material which are stacked on each other. In each of the aforementioned solutions, the synthetic material is preferably a composite material, including a synthetic resin incorporating reinforcement fibres, such as glass fibres, carbon fibres or aramid fibres.

Therefore, in such preferred embodiment the cross-member structure of the invention has a hybrid composition, which is partially metallic and partially constituted of composite material.

According to a further preferred feature of the present invention, each end portion of said hollow frame has an upper wall and a lower wall superimposed upon, and spaced from, each other, and having two pairs of holes aligned with each other along two vertical axes which are mutually spaced along the longitudinal direction of the motor-vehicle, with reference to the mounted condition of said auxiliary cross-member structure on the motor-vehicle body. Said pairs of holes are provided for being used both for mounting two elastic bushings for connection of a respective oscillating arm of the motor-vehicle front suspension, and for the engagement of connecting members for connecting the auxiliary cross-member structure to the motor-vehicle body. Preferably, the two aforementioned pairs of holes having said two vertical axes located at each end of the auxiliary cross-member structure constitute the only connection points of the auxiliary cross-member structure to the motor-vehicle body.

Thanks to the aforementioned features, the auxiliary cross-member structure has only four connection points to the motor-vehicle body. Furthermore, the portions of the auxiliary cross-member structure which identify the four connection points are also used for mounting elastic bushings for the connection of a respective oscillating arm of the suspension, which again considerably simplifies both the cross-member structure and the assembly operations. This result is achieved also due to that the structure is provided for receiving both the elastic bushings for connecting each oscillating arm, which bushings are orientated according a vertical axis, whereby each bushing can be used also for the engagement of a connecting screw of the auxiliary cross-member structure to the motor-vehicle body.

Furthermore, thanks to the aforementioned features, as illustrated in FIGS. 10, 11 , the provision of the additional uprights 3 B of the known solution is no longer needed, which implies a reduction of the weight of the cross-member structure and a simplification of the operations for manufacturing the cross-member structure and for assembling thereof on the motor-vehicle body.

Finally, in the preferred embodiment which has the additional filling structure within the metal sheet hollow frame of the cross-member structure, the use of composite materials with reinforcement fibres enables the required strength characteristics to be achieved with a total weight of the structure considerably reduced compared to the known solutions.

Further features and advantages of the invention will become apparent from the following description with reference to the annexed drawings, given purely by way of non limiting example, in which:

FIG. 1 is a perspective view of a preferred embodiment of the auxiliary cross-member structure according to the invention, with one of the two oscillating arms of the suspension illustrated in the mounted condition on the cross-member structure,

FIG. 2 shows an exploded view of a detail of one end of the cross-member structure of FIG. 1 ,

FIG. 3 is a further perspective view of the cross-member structure according to the invention, without the oscillating arms of the suspension,

FIGS. 4, 5 are perspective views which show two consecutive steps of the manufacturing operations of the auxiliary cross-member structure according to the invention,

FIG. 6 is a perspective view in an inverted position of the preferred embodiment of the auxiliary cross-member structure according to the invention,

FIG. 7 is a view of the plan layout of the metal sheet which constitutes the blank from which the metal sheet of the auxiliary cross-member structure according to the invention is obtained,

FIG. 8 is a perspective view of the cross-member structure according to the invention, with a cross-section according to a plane perpendicular to the longitudinal direction of the motor-vehicle, with reference to the mounted condition of the cross-member structure on the motor-vehicle body,

FIG. 9 is a perspective view in an inverted position of the cross-member structure in a second embodiment of the present invention, and

FIGS. 10, 11 are a general perspective view and a partial perspective view of an auxiliary cross-member structure according the prior art, as already described above.

With reference to FIGS. 1-9 , the parts which correspond to those illustrated in FIGS. 10, 11 relating to the prior art are designated by the same reference numbers.

In the preferred embodiment according to the invention, the auxiliary cross-member structure is generally designated by reference number 1 and comprises a metal sheet frame 2 in the form of a hollow shell, which is constituted by a single metal sheet S (illustrated in a planar developed condition in FIG. 7 ) folded on itself.

The metal sheet S is folded so as to define a metal frame with a substantially flattened and elongated configuration having at each end an upper wall 3 C and a lower wall 4 C arranged parallel to and spaced from each other.

In the preferred embodiment, the hollow metal frame thereby defined has an upper face 3 which is substantially continuous, whereas on its lower side said metal frame has lower wall portions 4 C provided only at the ends of the cross-member and a lower wall portion 4 D provided at an intermediate position between the ends of the cross-member structure. In order to define this structure, the metal blank S has an elongated central portion 3 which defines the aforementioned upper main wall of the cross-member metal frame. The central portion 3 comprises two lateral webs 30 , 31 ( FIG. 7 ) which, in the final folded condition of the metal sheet S, define a front edge 30 and a rear edge 31 which protrude downwardly from the upper main wall 3 .

Again with reference to FIG. 7 , at each end of the central portion 3 , the metal blank S comprises a pair of connecting fins 40 , 41 protruding from opposite sides of the central portion 3 . The connecting fins 40 , 41 are overlapped to each other in the folded final configuration of the metal sheet S and are mutually welded in order to define the lower wall portions 4 C ( FIG. 6 ).

The folding operation of the metal blank S is preferably performed around folding lines which are all parallel to the longitudinal direction of the cross-member.

The above described configuration of the hollow metal frame of the cross-member structure with an upper main wall 3 which is substantially continuous and including at the lower side only lower wall portions 4 C, 4 D, constitutes one of the possible solutions which have the advantage of a significant reduction of the weight of the structure. However, it is evident that any other configuration can be used, while always obtaining the main hollow metal frame of the cross-member structure starting from a single metal sheet. Therefore, it would be also possible to provide a starting blank configured so as to define a continuous main wall also on the lower face of the cross-member structure.

In the preferred embodiment herein described, the portion of intermediate lower wall 4 D is defined by a connection fin 4 D which protrudes from one side of the central portion 3 of the blank S. In the folded configuration, the free end of the fin 4 D is overlapped and welded to the front edge 30 of the cross-member structure.

Again with reference in particular to FIGS. 1-3 and 7 , the two parallel and spaced walls 3 C, 4 C are provided at each end of the metal frame of the cross-member structure. The walls 3 C, 4 C have two pairs of holes F 1 , F 2 aligned with each other along two vertical axes X 1 , X 2 which are mutually spaced along the longitudinal direction. The holes F 1 , F 2 are used both for mounting two elastic bushings B 1 for connection of a respective oscillating arm T, and for engaging connecting members for connection of the auxiliary cross-member structure to the motor-vehicle body. FIGS. 1, 2 of the annexed drawings show one of the two oscillating arms T with an external end carrying a bushing C for the connection of the respective wheel (not illustrated) to the wheel support, said oscillating arm having branches on its internal side, these branches terminating with bushing portions B for mounting the elastic bushings B 1 . Therefore, in the case of the present invention, both elastic bushings B 1 for connection of each oscillating arm T are oriented with their axes arranged vertically. Thanks to this feature, the pairs of holes F 1 , F 2 can be used not only for mounting the elastic bushings B 1 , also for engaging connection screws of the cross-member structure 1 to the motor-vehicle body.

In the preferred embodiment of the invention, the four attachment points of the cross-members structure 1 to the motor-vehicle body, which are identified by two front axes X 1 and two rear axes X 2 located at opposite ends of the cross-member structure, constitute the only connection points of the auxiliary cross-member structure to the motor-vehicle body. Therefore, compared to the known solution illustrated in FIG. 10 , the preferred embodiment of the cross-member structure according to the invention has only four points of connection to the motor-vehicle body, instead of six connection points. Furthermore, as previously indicated, the four points of connection to the motor-vehicle body are also used for mounting the elastic bushings B 1 for connection of the oscillating arms of the suspension.

Therefore, as it may be seen, the cross-member structure according to the invention provides a significant simplification both with reference to the manufacture of the cross-member structure and with reference to the operations for assembling the auxiliary cross-member structure on the motor-vehicle body. Also, the weight of the cross-member structure is considerably reduced, due to the above described simplification and the elimination of the uprights 3 B illustrated in FIG. 10 .

Similarly to the known solution, the cross-member structure 1 according to the invention incorporates two pairs of bushings B 2 with vertical axis, for engagement of connection screws which are used for mounting on the cross-member structure a control device for steering the motor-vehicle front wheels. Also, according to the known solution of FIG. 10, 11 , the cross-member structure according to the invention has at an intermediate area (specifically in the area in which the intermediate portion of the lower wall 4 D is provided), a bushing with vertical axis B 3 which is used for engaging a connecting screw for mounting a bracket (not illustrated) intended to be connected to the powertrain structure of the motor-vehicle with a pivoted arm. As for the known solution of FIG. 10, 11 , these details of construction are not herein illustrated since they are known and do not fall, taken alone, within the scope of the invention.

With the purpose of further reducing the weight of the auxiliary cross-member structure also through the use of a metal sheet with a lower thickness, while not affecting the required strength characteristics, the preferred embodiment of the invention provides an additional filling structure within the hollow metal body of the cross-member structure, which filling structure is preferably constituted at least partially of synthetic material, preferably a composite material including a synthetic resin incorporating reinforcement fibres (such as glass fibres, carbon fibres or aramid fibres). FIGS. 4-6 and 8 show by way of example an additional filling structure having a honeycomb configuration, with vertical axis cells.

The production and the configuration of the additional filling structure could be also different from the examples herein illustrated. For example, the configuration could be a sandwich configuration, including several panels of metal sheet and synthetic material, preferably composite material, stacked on each other. FIG. 9 shows an alternative embodiment in which the additional filling structure, indicated by R 1 , has a lattice configuration formed by intersecting vertical laminar elements.

FIGS. 4, 5 show two subsequent steps of the production of the aforementioned preferred embodiment of the auxiliary cross-member structure according to the invention. The additional filling structure (generally designated by reference R) is arranged in contact with a lower face of the central main portion 3 of the blank S before folding the connecting fins 40 , 41 , 42 of the metal blank S. Even prior to this step, to said lower face of the central portion 3 of the metal blank S (see FIG. 4 ) the ends adjacent thereto of the vertical bushings B 2 , B 3 are welded. The additional structure R can be for example secured by means of adhesives, rivets or thermal junctions, through holes and slots on the main portion 3 of the blank S.

As already above indicated, also the specific details relating to the configuration of the metal frame of the cross-member structure might vary with respect to what has been described and illustrated herein by way of example, while always providing at least the body constituting the main portion of the metal structure by starting from a single folded metal sheet.

Naturally, while the principle of the invention remains the same, the details of construction and the embodiments may widely vary with respect to what has been described and illustrated purely by way of example, without departing from the scope of the present invention.