Energy-absorbing device

Abstract

The invention relates to an energy-absorbing device (1) for a motor vehicle, comprising: a pre-formed composite sheet (2), a plastic material (3) overmolded onto said composite sheet (2), said plastic material (3) containing, in particular, polypropylene, and comprising, in particular, cells (4) formed by ribs (5) adjacent to said composite sheet (2), and this energy-absorbing device (1) being configured to be fixed to a structural frame (6) of the front end of a vehicle. Abstract figure: Fig. 1

Description

Title of the invention: Energy-absorbing device

[0001] The invention relates to an energy-absorbing device intended to absorb energy during a collision, particularly in the field of motor vehicles. This device is notably mounted on the front of the vehicle.

[0002] French patent application FR3064567 discloses an energy-absorbing device arranged to be mounted between a bumper and a side member of a motor vehicle. This energy-absorbing device comprises at least one insert, in particular made of composite material, including at least three longitudinal walls extending from the bumper towards the side member, when the energy-absorbing device is mounted between the bumper and the side member, and a plastic material structure at least partially enveloping the insert, this structure being in particular made by overmolding the insert with the plastic material.

[0003] The present invention aims in particular to improve solutions for absorbing shock energy on a vehicle.

[0004] The invention relates in particular to an energy-absorbing device for a motor vehicle, comprising: - a pre-formed composite sheet, - a plastic material overmolded on said composite sheet, said plastic material containing in particular polypropylene, and comprising in particular cells formed by ribs adjacent to said composite sheet, and this energy-absorbing device being configured to be fixed on a front-end structural frame of a vehicle.

[0005] According to one aspect of the invention, the energy-absorbing device is separate from a bumper beam of the vehicle and is configured to be placed at a distance from it.

[0006] According to one aspect of the invention, the energy-absorbing device is a secondary device for shock absorption, intended to complement other energy-absorbing devices already present on the front of the vehicle.

[0007] Advantageously, the energy-absorbing device makes it possible to add a shock-absorbing function to a front end that traditionally lacks such a function, this function being present at the bumper. In particular, the energy-absorbing device improves the resistance to frontal impacts, especially above the bumper beam, where traditional structures do not have an absorption function.

[0008] The use of polypropylene (which is less good in terms of mechanical resistance than polyamide, for example) in the energy-absorbing device of the invention allows for reduced manufacturing costs while maintaining satisfactory mechanical properties for shock absorption thanks to the composite sheet.

[0009] The energy-absorbing device comprising the composite sheet and the overmolded polypropylene plastic material exhibits mechanical performance substantially equivalent to that of an energy-absorbing device made entirely of polyamide. Indeed, the composite sheet 2 provides sufficient rigidity and strength to absorb impact energy effectively, even when polypropylene is used.

[0010] The use of lighter materials, such as polypropylene, helps to reduce the overall carbon footprint of the vehicle.

[0011] According to one aspect of the invention, the energy-absorbing device has a front end oriented towards the front of the vehicle and a rear end oriented towards the rear of the vehicle, the energy-absorbing device having an overall flared shape towards the rear.

[0012] The flared shape of the composite sheet towards the rear improves the mechanical resistance of the device during a frontal impact.

[0013] According to one aspect of the invention, the composite sheet has, in cross-section, a larger perimeter at the rear end of the energy-absorbing device than at its front end.

[0014] According to one aspect of the invention, the composite sheet can be thermoformed before being overmolded with the plastic material.

[0015] According to one aspect of the invention, the composite sheet is partially uncovered, namely certain parts of said composite sheet not being covered by the overmolded plastic material.

[0016] According to one aspect of the invention, the composite sheet has a corrugated shape with waves or undulations.

[0017] According to one aspect of the invention, the corrugations of the composite sheet are oriented in a longitudinal direction of the vehicle, namely in a front-to-rear direction of the vehicle. Thus, the troughs and crests of the corrugations are oriented in the longitudinal direction of the vehicle.

[0018] This allows for high mechanical resistance in the event of a frontal impact.

[0019] According to one aspect of the invention, the undulations of the composite sheet gradually widen in cross-section as one moves away from the front end of the energy-absorbing device.

[0020] According to one aspect of the invention, the composite sheet contains a reinforcing material such as carbon and / or glass fibers (possibly initially in the form of a sheet), this reinforcing material being impregnated with plastic resin, in particular thermoplastic material.

[0021] According to one aspect of the invention, the energy-absorbing device comprises a single composite sheet.

[0022] Alternatively, the energy-absorbing device comprises several composite sheets, which may in particular be in mirror symmetry with respect to each other.

[0023] The composite sheets can be pressed together.

[0024] According to one aspect of the invention, when two composite sheets are present, These composite sheets define a hollow volume between them.

[0025] The volume is for example composed of hollow tubes formed by the undulations of the composite sheets which are pressed against each other.

[0026] The composite sheet(s) may include one or more cutouts for the passage of shapes of the overmolded plastic material.

[0027] According to one aspect of the invention, the energy-absorbing device is configured to be fixed to a side member of the vehicle.

[0028] According to one aspect of the invention, the structural frame to which the energy-absorbing device is attached is configured to accommodate a lock for keeping a hood closed.

[0029] According to one aspect of the invention, the composite sheet can extend over 50%, 60%, or 70% at most of the height of the energy-absorbing device.

[0030] The invention further relates to a front end assembly for a motor vehicle comprising: - a structural frame attached to one or more of the vehicle's side members, - two energy-absorbing devices as described above, positioned on either side of said structural frame and attached to this structural frame.

[0031] According to one aspect of the invention, the energy-absorbing devices are placed at a distance from the vehicle's bumper beam.

[0032] According to one aspect of the invention, the two energy-absorbing devices are mounted on fixing elements on the structural frame.

[0033] The invention further relates to a method for manufacturing an energy-absorbing device for a motor vehicle, comprising the following steps: - to pre-form a composite sheet, in particular by thermoforming, so as to give it a predefined shape, said shape notably exhibiting undulations or waves, - place the composite sheet in an overmolding mold, - inject a plastic material, including polypropylene, onto the pre-formed composite sheet.

[0034] According to one aspect of the invention, the composite sheets used in the energy-absorbing device can be pre-assembled together before overmolding with the plastic material.

[0035] The invention further relates to a method of mounting an energy-absorbing device within the front face of a motor vehicle, said energy-absorbing device comprising fastening elements, comprising the following steps: - place the energy-absorbing device in the location on the structural frame, in particular at a distance from a vehicle bumper beam, - fix the energy-absorbing device to the structural frame using in particular screws or bolts or any other mechanical fastener.

[0036] Other features and advantages of the present invention will become more apparent upon reading the following description, provided by way of illustration and not limitation, and the accompanying drawings in which:

[0037] [Fig-1] Fig. 1 is a schematic, perspective representation of a device energy absorber according to an example of implementation of the invention;

[0038] [Fig.2] Fig.2 is a schematic representation of the composite sheet of the energy absorption device of the [Fig.l];

[0039] [Fig.3] Fig.3 is a schematic, cross-sectional representation of the device energy absorber of the [Fig.l];

[0040] [Fig.4] Fig.4 is a schematic, perspective representation of a device energy absorber according to another example of implementation of the invention;

[0041] [Fig. 5] Fig. 5 is a schematic representation of the composite sheets of the energy absorption device of the [Fig.4];

[0042] [Fig.6] Fig.6 is a schematic representation of the front face according to a example of implementation of the invention.

[0043] Figure 1 represents an energy-absorbing device 1 for a motor vehicle, according to an embodiment of the invention, comprising: - a preformed composite sheet 2 (represented in [Fig.2]), - a plastic material 3 overmolded onto said composite sheet 2, said plastic material 3 being polypropylene, and comprising cells 4 formed by ribs 5 adjacent to the composite sheet 2.

[0044] The plastic material 3 defines a body for the energy-absorbing device 1.

[0045] The energy-absorbing device 1 is configured to be fixed to a structural frame 6 of the front face of a vehicle.

[0046] The energy-absorbing device 1 is separate from a bumper beam 7 of the vehicle and is configured to be placed at a distance from it, as schematically illustrated in [Fig.6].

[0047] The energy-absorbing device 1 is a secondary device for shock absorption, intended to complement other energy-absorbing devices 8 already present on the front of the vehicle, and attached to the bumper beam 7.

[0048] The energy-absorbing device 1 adds a shock-absorbing function to a front face that is traditionally lacking such a function, this being normally present at the bumper 7. In particular, the energy-absorbing device 1 improves the ability to withstand frontal impacts, especially above the bumper beam 7, where traditional structures do not have an absorption function.

[0049] The use of polypropylene in the plastic material 3 of the energy-absorbing device 1 reduces manufacturing costs while maintaining sufficient mechanical properties for shock absorption thanks to the composite sheet 2.

[0050] The energy-absorbing device 1 has a front end 9 oriented towards the front of the vehicle and a rear end 10 oriented towards the rear of the vehicle, the energy-absorbing device 1 having an overall flared shape towards the rear.

[0051] The flared shape of the composite sheet 2 towards the rear end 10 improves the mechanical resistance of the energy-absorbing device 1 during a frontal impact.

[0052] The composite sheet 2 has, in cross-section, a perimeter 11 larger at the rear end 10 of the energy-absorbing device 1 than at its front end 9.

[0053] The composite sheet 2 can be thermoformed before being overmolded with the plastic material 3.

[0054] The composite sheet 2 is partially uncovered, some parts 12 of said composite sheet 2 not being covered by the overmolded plastic material 3.

[0055] The composite sheet 2 has a wavy shape with waves or undulations 13, as can be clearly seen in Figures 2 and 3.

[0056] The corrugations 13 of the composite sheet 2 are oriented in a longitudinal direction L of the vehicle, namely in a front-to-back direction of the vehicle, so that the troughs 14 and the peaks 15 of the corrugations 13 are also oriented in this direction L.

[0057] The undulations 13 of the composite sheet 2 gradually widen in cross-section (in a plane perpendicular to the direction L) when moving away from the front end 9 of the energy-absorbing device 1.

[0058] The energy-absorbing device 1 may comprise a single composite sheet 2, as in the example of Figures 1 to 3.

[0059] Alternatively, as illustrated in Figures 4 and 5, the energy-absorbing device 1 may comprise two composite sheets 2a, 2b, which may be in mirror symmetry with respect to each other.

[0060] The composite sheets 2a, 2b can be plated against each other.

[0061] When two composite sheets 2a, 2b are present, they define a hollow volume 16 between them, composed for example of hollow tubes 17 formed by the undulations 13 of the composite sheets 2a, 2b pressed against each other.

[0062] The composite sheets 2a, 2b may have cutouts 18 to allow the passage of shapes 19 of the overmolded plastic material 3.

[0063] The energy-absorbing device 1 is configured to be fixed to a longitudinal member 20 of the vehicle.

[0064] The structural frame 6 to which the energy-absorbing device 1 is attached is configured to accommodate a lock 21 intended to keep a hood 50 closed.

[0065] The composite sheet 2 can extend over 50%, 60%, or 70% at most of the height H of the energy-absorbing device 1.

[0066] We thus have a front end assembly 23 of a motor vehicle which comprises: - the structural frame 6 fixed to one or more of the vehicle's longitudinal members 20, - two energy-absorbing devices 1 positioned on either side of said structural frame 6 and attached to said structural frame 6.

[0067] The two energy-absorbing devices 1 are mounted on fixing elements provided on the structural frame 6.

[0068] The process for manufacturing an energy-absorbing device 1 for a motor vehicle comprises the following steps: - preform a composite sheet 2, in particular by thermoforming, so as to give it a predefined shape, said shape having in particular undulations 13 or waves. - place the composite sheet 2 in an overmolding mold 25. - inject a plastic material 3, including polypropylene, onto the pre-formed composite sheet 2.

[0069] The composite sheets 2a, 2b used in the energy-absorbing device 1 can be pre-assembled together before overmolding with the plastic material 3.

[0070] The method for mounting an energy-absorbing device 1 within the front face of a motor vehicle comprises the following steps: - place the energy-absorbing device 1 in the location provided on the structural frame 6, in particular at a distance from a bumper beam 7 of the vehicle. - fix the energy-absorbing device 1 to the structural frame 6 using fasteners 24, including screws, bolts or any other mechanical fasteners.

Claims

Demands

1. Energy-absorbing device (1) for a motor vehicle, comprising: - a preformed composite sheet (2; 2a; 2b), - a plastic material (3) overmolded onto said composite sheet (2; 2a; 2b), said plastic material (3) containing in particular polypropylene, and comprising in particular cells (4) formed by ribs (5) adjacent to said composite sheet (2; 2a; 2b), and this energy-absorbing device (1) being configured to be fixed to a front-end structural frame (6) of a vehicle.

2. Energy-absorbing device (1) according to the preceding claim, wherein the energy-absorbing device (1) has a front end (9) oriented towards the front of the vehicle and a rear end (10) oriented towards the rear of the vehicle, the energy-absorbing device (1) having an overall flared shape towards the rear, and the composite sheet (2; 2a; 2b) has, in cross-section, a perimeter (11) larger at the rear end (10) of the energy-absorbing device (1) than at its front end (9).

3. Energy-absorbing device (1) according to any one of the preceding claims, wherein the composite sheet (2; 2a; 2b) is partially uncovered, namely certain parts of said composite sheet (2; 2a; 2b) not being covered by the overmolded plastic material (3).

4. Energy-absorbing device (1) according to any one of the preceding claims, wherein the composite sheet (2; 2a; 2b) has a corrugated shape with waves or undulations (13), and the undulations (13) of the composite sheet (2; 2a; 2b) are oriented in a longitudinal direction of the vehicle.

5. Energy-absorbing device (1) according to any one of the preceding claims, wherein the energy-absorbing device (1) comprises a single composite sheet (2).

6. Energy-absorbing device (1) according to any one of claims 1 to 4, wherein the energy-absorbing device (1) comprises several composite sheets (2a; 2b), these being able in particular to be in mirror symmetry with respect to each other, and composite sheets can notably be pressed against each other.

7. Energy-absorbing device (1) according to the preceding claim in combination with claim 4 wherein, when two composite sheets (2a; 2b) are present, these composite sheets define a hollow volume (16) between them, the volume is for example composed of hollow tubes (17) formed by the undulations (13) of the composite sheets which are pressed against each other.

8. Energy-absorbing device (1) according to any one of the preceding claims, wherein the energy-absorbing device (1) is configured to be fixed to a side member (20) of the vehicle.

9. Front end assembly (23) of a motor vehicle comprising: - a structural frame (6) fixed to one or more side members (20) of the vehicle, - two energy-absorbing devices (1) according to any one of the preceding claims, positioned on either side of said structural frame (6) and attached to this structural frame (6).

10. Assembly according to the preceding claim, wherein the energy-absorbing devices (1) are placed at a distance from the bumper beam (7) of the vehicle.

11. Method of mounting an energy-absorbing device (1) according to any one of claims 1 to 8, within the front face of a motor vehicle, said energy-absorbing device (1) comprising fastening elements, comprising the following steps: - placing the energy-absorbing device (1) in the location on the structural frame (6), in particular at a distance from a bumper beam (7) of the vehicle, - fixing the energy-absorbing device (1) on the structural frame (6) using in particular screws or bolts or any other mechanical fastening element.

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