Front bumper sub-assembly for a motor vehicle

Abstract

The invention relates to a front bumper sub-assembly (1) for a motor vehicle, comprising a shield (100) and an absorber (200) mounted on the shield via attachment means (140, 150) provided on the shield and cooperating with complementary means (210, 220) provided on the absorber, said attachment means comprising: - a first attachment member projecting longitudinally from a first side portion of the shield and cooperating with a hole provided in a corresponding first end side portion (200A) of the absorber, and - a second attachment member extending in a transverse direction from the rear face of the second side portion of the shield and interlocking with an elongate cavity extending in a transverse direction in the second end side portion (200B) of the absorber.

Description

Description Title of the invention: Front bumper subassembly for a motor vehicle [Technical field] [1] The present invention claims priority from French application 2211853 filed on November 15, 2022, the content of which (text, drawings and claims) is incorporated herein by reference. [2] The present invention relates generally to shock absorption systems for motor vehicles. It relates in particular to a front bumper subassembly for a motor vehicle consisting of a bumper shield and an absorber made of expanded polymer material. [Earlier technique] [3] In order to comply with current approvals, modern vehicles are equipped with a shock absorption system adapted to manage frontal impacts between the vehicle and a pedestrian, particularly at the level of the legs. The objective is on the one hand to absorb the energy of the impact and on the other hand to limit injuries inflicted on the pedestrian and prevent them from passing under the vehicle. [4] For this purpose, the shock absorption system generally comprises two parts, a part called the “lower track” and a part called the “higher track”, and the performance in terms of pedestrian impact at the level of the legs is ensured by a compromise in stiffness between the high track and the lower track. [5] The low track is positioned at the level of the central deflector of the vehicle's front bumper and will "whip" the pedestrian's lower leg to prevent the latter from passing under the vehicle. The high track is positioned at the level of the vehicle's front bumper beam and dissipates the energy of the impact in order to limit injuries to the pedestrian. [6] The objective is to extend the leg as much as possible in order to limit the shearing of the knee. To this end, the high track includes an energy absorption device generally referred to as an "absorber" which is located between the beam bumper and the vehicle's bumper shield. The crushing of this absorber, during a collision, will place the upper track in a position further back than the lower track in relation to the vehicle, thereby causing the pedestrian's leg to lie down in the direction of the vehicle's hood. [7] Furthermore, the bumper must have good resistance in the longitudinal direction of the vehicle. In particular, it must not sink more than 10 mm when supported by 25 kg along the longitudinal axis of the vehicle. The shock absorption system must therefore be able to ensure both the resistance of the bumper and good dissipation of energy in the event of a pedestrian impact. A compromise must then be found to ensure these two opposing services. [8] In order to ensure good energy dissipation while having the ability to return to position after being deformed during a minor impact such as a “parking impact”, the absorber is generally formed in a single block made from an expanded polymer material such as expanded polypropylene (EPP) or expanded polystyrene (EPS). [9] Presenting an elongated shape and occupying almost all of the space separating the upper bumper beam and the bumper shield, this absorber is conventionally mounted by the supplier on the bumper shield and the subassembly thus constituted is then delivered to the manufacturer to be mounted on the body structure of the vehicle at the edge of the assembly line.

[0010] Intended to be housed in a constrained space after the bumper sub-assembly has been fitted, the mounting of the absorber on the shield is solely intended to ensure its retention during transport and until the bumper sub-assembly is fitted to the vehicle body structure.

[0011] This support is conventionally ensured by two attachment members projecting longitudinally from the two lateral end portions of the rear face of the shield and cooperating by clipping or piggybacking, when mounting this absorber on the shield by a longitudinal translational movement, in two respective through holes provided in the lateral portions of this absorber.

[0012] In use, and particularly due to its expanded polymer composition, the absorber tends to separate from the shield during transport, which forces operators to waste valuable time repositioning it on the bumper at the edge of the assembly line so that this bumper sub-assembly can be mounted on the vehicle body structure. [Statement of the invention]

[0013] The present invention therefore aims to improve the situation.

[0014] To this end, it proposes a front bumper subassembly for a motor vehicle, comprising a bumper shield and an absorber made of expanded polymer material mounted on said shield by means of attachment means provided on this shield and cooperating with complementary means provided on this absorber, said attachment means comprising a first attachment member projecting longitudinally from a first lateral end portion of the rear face of said shield and cooperating by clipping or interlocking with a through hole provided in a corresponding first lateral end portion of said absorber;characterized in that said attachment means also comprise a second attachment member taking root from the rear face of the second lateral end portion of said shield, said second attachment member comprising a finger extending in a substantially transverse direction and cooperating by fitting with an elongated cavity extending in a substantially transverse direction in the second lateral end portion of said absorber.;

[0015] The interlocking cooperation between the finger of the second attachment member and the cavity makes it possible to considerably limit the risk of complete detachment of the absorber from the shield, so that this absorber can be reattached much more quickly to this shield in the event of accidental unclipping or unstacking of the first attachment member.

[0016] According to preferred characteristics of said front bumper subassembly according to the invention: - said second attachment member comprises a base projecting longitudinally from the rear face of said shield and carrying at its rear top end said finger; - said second attachment member also comprises at least one rib of stiffening in the form of a square extending along a substantially horizontal plane at the level of the connection zone between said base and said finger, being supported by two of its sides against these two elements; - the distal portion of said finger tilts obliquely forward so as to exert a bearing force against the front portion of an inner peripheral wall of said absorber delimiting said cavity; - said finger has a length of between 5 and 15 centimeters; - said finger has a pointed free end; - said first attachment member comprises a longitudinally oriented clipping tab provided at its rear free end with a tooth formed by an inclined ramp extending to a retaining step; - said hole has a front portion extending in a funnel from the front face of said absorber, narrowing to a bottleneck whose width is less than that of the tooth of said tab; and / or - said shield comprises an outer skin as well as two inner reinforcing elements each fixedly attached against a corresponding lateral part of said outer skin, said first and second attachment members each being molded in a single piece with a respective said inner reinforcing element.

[0017] The invention also relates, in a second aspect, to a motor vehicle comprising such a front bumper subassembly. [Brief description of the drawings]

[0018] The description of the invention will now be continued by the detailed description of an exemplary embodiment, given below for illustrative but non-limiting purposes, with reference to the appended drawings, in which: - [Fig 1] represents a three-quarter rear perspective view of a front bumper subassembly according to the invention; - [Fig 2] is a rear three-quarter perspective view of the bumper shield included in the bumper subassembly according to the invention; - [Fig 3] represents a three-quarter rear perspective view of the absorber included in the bumper subassembly according to the invention; - [Fig 4] is a sectional view along a horizontal cutting plane illustrating an intermediate stage of mounting the absorber on the bumper shield; and - [Fig 5] represents a sectional view along a horizontal cutting plane taken at the end of assembly of the absorber on the bumper shield. [Detailed description]

[0019] Figure 1 represents a three-quarter rear perspective view of a front bumper subassembly 1 according to the invention intended to be mounted on the body structure of a motor vehicle not shown.

[0020] In the description which follows and by convention, when referring to qualifiers of orientation (such as the terms “vertical”, “transverse” or “horizontal”) or position (such as the terms “front”, “rear”, "upper" or "lower"), the latter will be defined in relation to the normal mounting position of this bumper sub-assembly 1 in a vehicle and following the normal direction of progression of the latter.

[0021] The terms "external" and "internal" will be used to define the relative position of an element with reference to the median vertical longitudinal plane of the vehicle. The element closest to this plane will thus be described as internal, as opposed to the other element further from this same plane, which will be described as external.

[0022] Finally, the term "substantially" will indicate that a slight deviation is permitted from a predetermined nominal position or arrangement, while remaining within the scope of the invention. For example, "substantially vertical" indicates that a deviation of the order of 15 to 20° from a strictly vertical orientation is permitted within the scope of the invention.

[0023] The front bumper subassembly 1 consists of a bumper shield 100 and an absorber 200 mounted against the rear face of this shield 100.

[0024] Shown alone in Figure 2, the bumper shield 100 comprises an outer skin 110 made from one or more plastic parts molded from a thermoplastic polymer such as Polypropylene (PP), Polyethylene (PE), polyamide (PA), Acrylonitrile Styrene Acrylate (ASA) or Acrylonitrile Butadiene Styrene / Polycarbonate (ABS / PC), possibly reinforced with natural and / or synthetic fibers.

[0025] This bumper shield 100 also comprises, at each of its lateral parts or crosspieces, two internal reinforcing elements 120, 130, each advantageously molded in a single piece from a thermoplastic polymer such as Polypropylene (PP) optionally reinforced with natural and / or synthetic fibers, and fixedly attached by welding or by clipping against the outer skin 110.

[0026] Shown alone in Figure 3, the absorber 200 consists of a single elongated block made of an expanded polymer material such as expanded polypropylene (EPP) or expanded polystyrene (EPS).

[0027] The term "expanded polymer material" means a cellular material formed from a solid polymer phase and a dispersed gas phase. This type of cellular material, sometimes called "foam", has the main advantages of being particularly light and having the ability to return to its original shape after being deformed.

[0028] Advantageously, an expanded polypropylene with a density of between 30 and 80 g / L, preferably between 30 and 45 g / L, will be used.

[0029] Intended to extend longitudinally between the upper bumper beam of the vehicle, not shown, and the bumper shield 100 so as to occupy almost all of the space separating this beam from this shield 100, the absorber 200 is mounted on this bumper shield 100 by means of attachment means provided on this shield 100 and cooperating with complementary means provided on this absorber 200.

[0030] With reference to Figure 2, these attachment means comprise a first attachment member 140 projecting longitudinally from a first lateral end portion of the rear face of the shield 100 and cooperating by clipping with a hole 210, visible in Figure 3, formed in a first corresponding lateral end portion 200A of the absorber 200.

[0031] Advantageously molded in one piece with the interior reinforcing element 120, this first attachment member 140 comprises a hollow barrel 141 projecting along a longitudinal axis from the rear face of the shield 100 and from the rear top wall of which a clipping tab 142 extends longitudinally towards the rear.

[0032] This tab 142 is provided at its rear free end with a tooth 143 formed by an inclined ramp extending to a retaining step.

[0033] Crossing longitudinally from one side to the other the absorber 200, the hole 210 has a front portion 211 extending in a funnel from the front face of this absorber 200, narrowing to a bottleneck whose width is less than that of the tooth 143 of the tongue 142.

[0034] This hole 210 also has a rear portion 212 extending in a funnel from this bottleneck, widening to the rear face of this absorber 20.

[0035] According to the invention and with reference again to FIG. 2, the attachment means also comprise a second attachment member 150 taking root from the rear face of the second lateral end portion of the shield 100.

[0036] Advantageously molded in one piece with the internal reinforcing element 130, this second attachment member 150 comprises a base with a “U” section 151 projecting along a longitudinal axis from the rear face of the shield 10 and carrying at its rear top end a finger 152 extending in a substantially transverse direction on the internal side and cooperating by fitting with an elongated cavity 220 extending in a substantially transverse direction in the second lateral end portion 200B of the absorber 200 and opening onto an inlet opening provided on the corresponding lateral end face 23 of this absorber 200.

[0037] According to an advantageous characteristic and as can be seen in FIG. 2, the distal portion 153 of this finger 152 tilts obliquely forward so as to exert a bearing force against the front portion of the inner peripheral wall of the absorber 200 delimiting this cavity 220.

[0038] In order to limit the thickness of plastic material at the finger 152, the latter is advantageously made hollow, its distal portion 153 having for example an “I” shaped section.

[0039] This finger 152, the length of which is advantageously between 5 and 15 centimeters, also preferably has a pointed free end so as to facilitate its introduction into the cavity 220.

[0040] In order to reinforce the mechanical strength of this finger 152, the second attachment member 150 also preferably comprises at least one stiffening rib in the shape of a right angle 154 (see figure 5) extending along a substantially horizontal plane at the level of the connection zone between the base 151 and the finger 152 while being supported by two of its sides against these two elements.

[0041] To mount the absorber 200 on the bumper shield 100, the operator must first, as illustrated in FIG. 4, position this absorber 200 opposite the rear face of this shield 100 in a direction slightly at an angle relative to a transverse direction so that its first lateral end portion 200A provided with the hole 210 is further away from the shield 100 than its second lateral end portion 200B in which the cavity 220 is formed.

[0042] This operator must then present the entry opening of this cavity 220 opposite the pointed free end of the finger 152 of the second attachment member 150, then translate this absorber 200 in a substantially transverse direction so as to cause the progressive introduction of the finger 152 inside the cavity 220 and this until its pointed free end comes to abut against the bottom of this cavity 220.

[0043] The first lateral end portion 200A of the absorber 200 must then be pushed longitudinally towards the shield 10 so that the free rear end of the tab 142 enters the funnel-shaped front portion 21A of the hole 21 and the tooth 143 comes into abutment against the bottleneck of the hole 210.

[0044] The continuation of this longitudinal translation movement causes the elastic deformation of the perimeter of this neck which widens so as to allow the tooth 143 to pass through it.

[0045] As soon as tooth 143 has completely crossed this neck, the latter gradually returns to its initial shape, so that the indentation of this tooth 143 now opposite the edge of this neck prevents the removal of tab 142.

[0046] Due to the expanded polymer material composition of the absorber 200, the risk of accidental unclipping of this tab 142 remains relatively high.

[0047] The interlocking cooperation between the finger 152 and the cavity 220, however, makes it possible to considerably limit the risk of complete detachment of the absorber 200 from the shield 100, so that this absorber 200 can be reattached much more quickly to this shield 100 at the edge of the assembly line so that this bumper subassembly 1 can be mounted on the body structure of the vehicle.

[0048] It will be noted that the bearing force exerted by the distal slanted portion 153 of this finger 152 against the front portion of the inner peripheral wall of the absorber 200 delimiting this cavity 220 makes it possible to further reduce the risk of the finger 152 exiting the cavity 200.

[0049] According to alternative embodiments not shown, the first and second attachment members may be shaped differently.

[0050] This is particularly the case for the clipping tab of the first attachment member and / or the finger of the second attachment member.

[0051] The first attachment member may also cooperate by interlocking with a through hole provided in a first corresponding lateral end portion of said absorber.

[0052] Finally, it is recalled that the present invention is not limited to the embodiments described and shown, but also encompasses all variants within the reach of those skilled in the art.

Claims

Claims

1. Front bumper subassembly (1) for a motor vehicle, comprising a bumper shield (100) and an absorber (200) made of expanded polymer material mounted on said shield (100) by means of attachment means (140, 150) provided on this shield (100) and cooperating with complementary means (210, 220) provided on this absorber (200), said attachment means comprising a first attachment member (140) projecting longitudinally from a first lateral end portion of the rear face of said shield (100) and cooperating by clipping or piling with a through hole (210) provided in a corresponding first lateral end portion (200A) of said absorber (200);characterized in that said attachment means also comprise a second attachment member (150) taking root from the rear face of the second lateral end portion of said shield (100), said second attachment member (150) comprising a finger (152) extending in a substantially transverse direction and cooperating by fitting with an elongated cavity (220) extending in a substantially transverse direction in the second lateral end portion (200B) of said absorber (200).;

2. Front bumper subassembly (1) according to claim 1, characterized in that said second attachment member (150) comprises a base (151) projecting longitudinally from the rear face of said shield (100) and carrying at its rear top end said finger (152).

3. Front bumper subassembly (1) according to claim 2, characterized in that said second attachment member (150) also comprises at least one stiffening rib in the shape of a square (154) extending along a substantially horizontal plane at the level of the connection zone between said base (151) and said finger (152) while being supported by two of its sides against these two elements.

4. Front bumper subassembly (1) according to one of claims 1 to 3, characterized in that the distal portion (153) of said finger (152) tilts obliquely forward so as to exert a bearing force against the front portion of an inner peripheral wall of said absorber (200) delimiting said cavity (220).

5. Front bumper subassembly (1) according to one of claims 1 to 4, characterized in that said finger (152) has a length of between 5 and 15 centimeters.

6. Front bumper subassembly (1) according to one of claims 1 to 5, characterized in that said finger (152) has a pointed free end.

7. Front bumper subassembly (1) according to one of claims 1 to 6, characterized in that said first attachment member (140) comprises a clipping tab (142) oriented longitudinally and provided at its rear free end with a tooth (143) formed of an inclined ramp extending to a retaining step.

8. Front bumper subassembly (1) according to claim 7, characterized in that said hole (210) has a front portion (211) extending in a funnel from the front face of said absorber (200) narrowing to a bottleneck whose width is less than that of the tooth (143) of said tab (142).

9. Front bumper subassembly (1) according to one of claims 1 to 8, characterized in that said shield (100) comprises an outer skin (110) as well as two inner reinforcing elements (120, 130) each fixedly attached against a corresponding lateral part of said outer skin (110), said first and second attachment members (140, 150) each being molded in one piece with a respective said inner reinforcing element (120, 130).

10. Motor vehicle comprising a front bumper subassembly (1) according to one of claims 1 to 9.

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