FRONT CROSS MEMBER ASSEMBLY FOR FRONT IMPACT TESTING WITH LOW OVERLAP

Description

technical field

[0001] The invention relates to the field of motor vehicles, in particular to the field of motor vehicle structures and their ability to successfully undergo impact tests, including frontal impact tests. Previous technique

[0002] There are a series of impact tests, or "crash tests," with standardized and recognized procedures, used to evaluate motor vehicles for their passive safety. In particular, there are impact tests specific to the American market, known as the "driver side small overlap front test" and the "passenger side small overlap front test," developed by the Insurance Institute for Highway Safety (IIHS). The IIHS is an independent, non-profit scientific and educational organization dedicated to reducing losses from motor vehicle accidents, including fatalities, injuries, and property damage. This test is designed to replicate what happens when the front left corner of a vehicle collides with another vehicle or an object such as a tree or pole. This crash test poses a challenge to some seat belt and airbag designs because the occupants are moved both forward and sideways within the vehicle.In the driver's side small overlap frontal impact test, a vehicle travels at 64 km / h toward a rigid barrier 150 cm high. A crash test dummy representing an average-sized man is placed in the driver's seat. Twenty-five percent of the vehicle's total width strikes the barrier on the driver's side. Most modern cars have roll cages encapsulating the passenger compartment and designed to withstand frontal and moderate overlap frontal impacts with minimal deformation. At the same time, crush zones help manage collision energy to reduce forces on the passenger compartment. The main structures of the crush zone are concentrated in the mid-section of the front end. When a crash involves these structures, the passenger compartment is protected from intrusion, and the front airbags and seat belts can effectively restrain and protect the occupants.Small overlap frontal collisions primarily affect the outer edges of a vehicle, which are not adequately protected by the crash zone structures. The collision forces are transmitted directly to the front wheel, the suspension system, and the front bulkhead. It is not uncommon for the wheel to be forced rearward into the floor, contributing to further intrusion into the passenger compartment and resulting in serious leg and foot injuries. To provide effective protection in small overlap collisions, the roll cage must withstand the collision forces that are not mitigated by the crash zone structures. For this purpose, it is known to incorporate a structural crossmember located at the front end and attached directly to the ends of the front frame rails.This crossbeam is structural in that it exhibits a certain rigidity and mass, and consequently a significant weight, for example at least 10 kg. Such mass inevitably poses ergonomic problems during its assembly.

[0003] The published patent document FR 3 031 952 A1 discloses a front fascia module comprising a front fascia crossmember and two side members configured for easy assembly with said front fascia crossmember, specifically via an insert-type connection system. This front fascia module thus has a reduced volume in its unassembled state and can be easily assembled while maintaining sufficient rigidity. However, this fascia module is limited to supporting various components such as the engine cooling radiator, headlights, and the front hood latch. It does not provide a rigid connection between the two crossmembers like the aforementioned structural crossmember. This document therefore fails to provide a solution to the aforementioned problem.

[0004] Document FR 2 870 197 A1 discloses a front vehicle module that includes a crossmember which, once installed, can obstruct access to the front of the engine compartment. To address this issue, the document proposes a temporary mounting system with hooks extending from the rear face of the crossmember. These hooks attach to the vehicle's side members to suspend the crossmember in an "intermediate" position, inclined forward. This position provides access to the engine compartment, thus facilitating the assembly of other components or maintenance work. This document therefore also fails to provide a solution to the aforementioned problem. Description of the invention

[0005] The invention aims to overcome at least one of the drawbacks of the aforementioned prior art. More specifically, the invention aims to facilitate the assembly of a structural crossmember at the front of a motor vehicle, the crossmember in question being intended to be fixed to the two longitudinal profiles or frame members of the vehicle's structure.

[0006] The invention relates to a motor vehicle comprising two longitudinal profiles extending forward from a passenger compartment part of the motor vehicle; a front front cross member; remarkable in that the front front cross member includes means for the temporary support, during assembly, of a structural cross member intended to connect the two longitudinal profiles.

[0007] According to an advantageous embodiment of the invention, the temporary support means comprise at least two hooks projecting forward.

[0008] According to an advantageous embodiment of the invention, the front facade cross member is made of plastic material, the temporary support means being integrally formed with said front facade cross member.

[0009] According to an advantageous embodiment of the invention, the temporary support means are configured to support a central portion of the structural crossbeam. Advantageously, the central portion of the structural crossbeam is transverse and straight.

[0010] According to the invention, the motor vehicle comprises the structural crossmember, said structural crossmember having an inverted U shape and comprising a central portion opposite the front face of the front fascia crossmember; and two lateral portions extending downwards from two ends of the central portion and fixed to the two longitudinal profiles, respectively.

[0011] According to an advantageous embodiment of the invention, each of the two lateral portions of the structural cross member comprises a plate fixed by screwing to a plate of the corresponding longitudinal profile.

[0012] According to an advantageous embodiment of the invention, each of the two lateral portions forms a hollow body with a cross-section decreasing towards the central portion of the structural cross member.

[0013] According to an advantageous embodiment of the invention, the at least two hooks are configured to extend under and in front of the central portion of the structural cross member or to fit into openings formed in an underside face of said central portion.

[0014] The at least two hooks advantageously form a support direction parallel to the direction of the main longitudinal portion. The at least two hooks are advantageously configured to support a straight portion of a structural cross member. The at least two hooks are advantageously configured to support a total load of at least 10 kg.

[0015] The invention also relates to a method of assembling said motor vehicle, comprising the following steps: (a) mounting a front fascia crossmember; (b) mounting a structural crossmember in front of the front fascia crossmember; notable in that the vehicle is according to the invention; and step (b) includes a provisional positioning of the structural crossmember on the provisional support means of the front fascia crossmember, and then a fixing of the structural crossmember to the two longitudinal profiles.

[0016] The features of the invention are interesting because they facilitate the assembly of the structural crossmember by providing temporary support in the mounting position. The structural crossmember is installed after the front panel crossmember, meaning that the latter is present at the time of the structural crossmember's installation. Furthermore, the structural crossmember is positioned in front of the front panel crossmember. The invention thus takes advantage of the front panel crossmember to facilitate the installation of a potentially heavy component that, otherwise, cannot be placed on any adjacent support surface, apart from the temporary support means provided by the invention.Positioning the lateral portions of the structural cross member opposite the front ends of the longitudinal profiles requires precise positioning in a transverse vertical plane, i.e. along the y and z axes in an orthonormal coordinate system where the x axis is a longitudinal axis, the y axis a horizontal transverse axis and the z axis a vertical axis, then positioning along the x axis can be finalized during fixing, for example when fixing deformable boxes ("crashboxes") in the extension, towards the front, of the longitudinal profiles. Brief description of the drawings

[0017] [ Fig 1 ] is a perspective representation of the front part of the structure of a motor vehicle according to the invention; [ Fig 2 ] is a detailed view of the front of the motor vehicle of the figure 1 ; Fig 3] represents a front facade cross member allowing temporary support, during assembly, of the structural cross member, according to a first embodiment of the invention; [ Fig 4 ] represents a front facade cross member allowing to temporarily support, during assembly, the structural cross member, according to a second embodiment of the invention. Detailed description

[0018] There figure 1 illustrates the front home of a motor vehicle structure conforming to the invention.

[0019] The motor vehicle 2 has two longitudinal profiles 4 at the front extending forward from the passenger compartment of the motor vehicle, under the floor of said vehicle; these longitudinal profiles are commonly referred to as stretchers, by analogy with the arms of a stretcher. A front bumper crossmember 6 is attached to the front ends of the longitudinal profiles 4 via two deformable compression boxes 8, commonly referred to by the Anglo-Saxon term "crashboxes".

[0020] The motor vehicle 2 is distinguished by a structural crossmember 10 that mechanically connects the ends of the two longitudinal profiles 4. The structural crossmember 10 has a general inverted U-shape, with a central portion forming a transverse profile and two lateral portions rigidly connected to the central portion and attached to the ends of the two longitudinal profiles 4. Each of the two lateral portions can form a hollow section with a cross-section that decreases towards the central portion. This crossmember is structural in that it is solid and provides substantial reinforcement to the structure of the motor vehicle. This reinforcement is intended to make the motor vehicle compliant with the small overlap crash test developed for the American market and mentioned earlier in the section 'Prior Technology'.In this crash test, the overlap between the obstacle and the front of the vehicle is so small that the obstacle avoids the longitudinal profile or crossmember located on the same side as the obstacle. Therefore, the bumper crossmember 8, the front wheel (not shown), and the front reinforcement 11 are responsible for absorbing the impact. As a result, the corresponding transverse profile 4 or crossmember tends to collapse, that is, to deform laterally towards the center of the vehicle. The structural crossmember 10 contains, or at least limits, this tendency and allows the vehicle to achieve a satisfactory result in the aforementioned test.

[0021] There figure 2 is a more detailed view of the front of the motor vehicle figure 1 In this view, the front bumper crossmember and the deformable boxes illustrated in the figure 1are absent. The structural cross member 10 is clearly visible, in particular the central portion 10.1, which is generally straight and transverse, and the two lateral portions 10.2 extending downwards from the ends of the central portion 10.1 and fixed to the front ends of the two longitudinal profiles (not visible). One can observe at the figure 2 the presence of a front fascia crossmember 12 directly behind the structural crossmember 10. The front fascia crossmember 12 is fixed at its ends to the wing linings (not shown) and serves as a support in particular for the internal combustion engine cooling radiator and / or the air conditioning system heat exchanger, the front headlights and / or the front hood lock, in a manner known per se.

[0022] According to the invention, the front fascia crossmember 12 is used as a temporary support for the structural crossmember 10 during its mounting on the motor vehicle. With reference to the description of the structural crossmember 10 made in relation to the figure 1 This component has a certain mass, typically weighing at least 10 kg. It is therefore particularly useful to be able to support it temporarily in the mounting position. Temporary support means are provided on the front facade cross member 12, advantageously on the front face of the front facade cross member 12, designed to support the central portion 10.1 of the structural cross member 10. The lateral portions 10.2 of the structural cross member 10 can thus be fixed to the front ends of the longitudinal profiles.

[0023] We observe at the figure 2that each of the lateral portions 10.2 has a plate fixed against a plate (not visible) at the front end of the corresponding longitudinal profile, by means of fixing screws through the fixing holes. Deformable boxes, as illustrated in the figure 1 , can then be fixed against the lateral portions 10.2 in line with the longitudinal profiles, in order to support the front bumper crossmember, as illustrated in the figure 1 .

[0024] There figure 3 illustrates a front facade cross member allowing temporary support, during assembly, of the structural cross member, according to a first embodiment of the invention.

[0025] The front fascia crossmember 12 comprises a main longitudinal portion 12.1 with two opposing ends, and fastening means 12.2 for said opposing ends. These fastening means 12.2 are, in this case, holes provided for attachment to the front fender liners and the front fenders. The front fascia crossmember 12 further comprises two hooks 12.3 projecting forward and configured to support the structural crossmember 10. The two hooks 12.3 are advantageously located on the front face of the main longitudinal portion 12.1 of the front fascia crossmember 12. In this case, each of the two hooks 12.3 has an L-shaped longitudinal cross-section, that is, with a generally horizontal portion projecting forward from the front fascia crossmember 12 and supporting a lower face of the central portion 10.1 of the structural cross member 10, and a generally vertical portion extending upwards in front of the central portion 10.1 of the structural cross member 10.

[0026] There figure 4 This illustrates a front facade crossmember that provides temporary support, during assembly, to the structural crossmember, according to a second embodiment of the invention. The reference numbers of the first embodiment are used to designate identical or corresponding elements of the second embodiment, these numbers being increased by 100. Reference is also made to the description of these elements in the first embodiment.

[0027] The second embodiment differs from the first embodiment in that the hooks 112.3 do not extend essentially vertically in front of the central portion 110.1 of the structural cross member 110 but rather in holes made in said central portion 110.1. These holes are made in an underside face of the central portion 110.1 of the structural cross member 110.

[0028] This configuration of the means of temporary support of the structural cross member is interesting in that these means, namely the hooks 112.3, do not extend to the front of the structural cross member 110, in particular its central portion 110.1, so as not to interfere with the elements of the motor vehicle located at the front of the structural cross member 110 and likely to move towards the cross member in question.

[0029] We can observe that the structural crossbeams 10 and 110 illustrated in figures 3 and 4are somewhat different from the one illustrated in figures 1 and 2 However, this does not change the principle of the invention and also shows that the invention is compatible with different structural crossbeam embodiments.

[0030] The two embodiments of the temporary support means for the structural crossbeam during assembly, described above, illustrate the invention in a non-limiting manner, it being understood that other embodiments are conceivable. For example, these temporary support means may comprise a single hook or more than two hooks. They may also be removable, that is, capable of being removed after the structural crossbeam has been assembled and / or specifically installed before the structural crossbeam is assembled.

[0031] Generally, the front facade crossmember can be made of plastic, using injection molding. For this purpose, the temporary support brackets are advantageously formed as a single unit with the front facade crossmember. Alternatively, however, they can be attached to the front facade crossmember.

[0032] The invention is, however, limited to the scope of the attached claims.

Claims

1. Motor vehicle (2) comprising: - two longitudinal sections (4) extending forwards from a passenger compartment portion of the motor vehicle; and - a front cross-member (12), the front cross-member (12; 112) having means (12.3; 112.3) for temporarily supporting, during assembly line, a structural cross-member (10; 110) for connecting the two longitudinal sections (4), characterised in that the motor vehicle comprises the structural cross-member (10; 110), said structural cross-member having an inverted U-shape and comprising: - a central portion (10.1; 110.1) facing the front cross-member (12; 112); - two lateral portions (10.2; 110.2) extending downwards from two ends of the central portion (10.1; 110.1) and fixed to the two longitudinal profiles (4), respectively.

2. Motor vehicle (2) according to Claim 1, characterised in that the temporary support means comprise at least two hooks (12.3; 112.3) projecting forwards.

3. Motor vehicle (2) according to one of Claims 1 and 2, characterised in that the front cross-member (12; 112) is made of plastic material, the temporary support means (12.3; 112.3) being integrally formed with said front cross-member.

4. Motor vehicle (2) according to one of Claims 1 to 3, characterised in that the temporary support means (12.3; 112.3) are configured to support a central portion (10.1; 110.1) of the structural cross-member (10; 110).

5. A motor vehicle (2) according to any one of the previous claims, wherein each of the two lateral portions (10.2; 110.2) of the structural cross-member (10; 110) comprises a plate screwed to a plate of the corresponding longitudinal section (4).

6. A motor vehicle (2) according to any one of the previous claims, wherein each of the two lateral portions (10.2; 110.2) forms a hollow body with a cross-section decreasing towards the centre portion (10.1; 110.1) of the structural cross-member (10; 110).

7. Motor vehicle (2) according to Claim 2 or any one of Claims 3 to 6 falling within the dependency of Claim 2, characterised in that the at least two hooks (12.3; 112.3) are configured to extend under and in front of the central portion (10.1) of the structural cross-member (10; 110) to be inserted into openings formed in a lower face of said central portion (110.1).

8. Method for assembling a motor vehicle (2), comprising the following steps: (a) assembly line of a front panel crossmember (12; 112); (b) assembly line of a structural cross-member (10; 110) at the front of the front cross-member (12; 112); wherein the motor vehicle (2) is according to one of Claims 1 to 7; and step (b) comprises a temporary positioning of the structural cross-member (10.1; 110.1) on the temporary support means (12.3; 112.3) of the front cross-member (12; 112), and then a fastening of the structural cross-member (10; 110) to the two longitudinal profiles (4).