EP1487671A1

EP1487671A1 - Bumper beam with shock absorber for motor vehicle

Info

Publication number: EP1487671A1
Application number: EP03738200A
Authority: EP
Inventors: Sébastien GUINEHUT; Jérôme LESTAVEL
Original assignee: Valeo Thermique Moteur SA
Current assignee: Valeo Thermique Moteur SA
Priority date: 2002-03-26
Filing date: 2003-03-25
Publication date: 2004-12-22
Also published as: FR2837762B1; WO2003080398A1; AU2003244717A1; FR2837762A1; JP2005520735A

Abstract

The invention relates to a bumper beam (10) which is intended, in particular, for the front panel of a motor vehicle. The inventive beam, which is made from a hybrid material, comprises a section (16) having an open cross-section. Said beam also comprises at least one shock absorber case (12) which is built into the bumper beam, said case being housed at least partially in the open cross-section of the aforementioned section (16) and comprising a jacket (30) which is filled with a metallic foam (38) having shock absorbing properties.

Description

RFR0060

Bumper beam with energy absorber for motor vehicle

The invention relates to a bumper beam intended in particular to form part of a front face of a motor vehicle.

It relates more particularly to a bumper beam, which can be called “hybrid beam”, since it is formed from a hybrid material from a profile, with an open section.

Bumper beams of this type are already known which consist of a metal section with open section, generally in the form of a C, forming an insert. This profile is overmolded and / or reinforced with a molding material, usually a possibly reinforced plastic material.

Current vehicles receive a front face, that is to say a structural element capable of integrating various vehicle equipment, such as headlights, turn signals, horn, heat exchange module, etc.

The front panel, thus provided with its equipment, constitutes a unitary module prepared and delivered by the supplier, and ready to be mounted on the vehicle by the manufacturer. The mounting of this unitary module is done by connection to lateral structural elements of the vehicle, such as side rails, wings, hulls, then fitting of a bumper attached to the module.

For this, the front face usually receives the bumper beam on which is subsequently mounted the "bumper proper, also called frontal shield. The front panel module must meet crash test (crash danner) requirements, namely not to deform the structure of the vehicle, minimize the damage to components and thus reduce repair costs. In addition, this module must ensure the safety of the occupants and that of the pedestrians.

The front face and the bumper beam constitute essential elements which participate respectively in the structure of the vehicle and of the module and in its protection.

The bumper beam has several roles. It must participate in the structure of the vehicle and protect the passengers of the vehicle in the event of an impact with an external obstacle, as well as the equipment of the vehicle, in particular in order to reduce the cost of repairs in the event of an accident. Conversely, the function of the bumper beam is to reduce the aggressiveness of the vehicle, in particular towards pedestrians, by absorbing the impact energy as much as possible so as to minimize the seriousness of the injuries inflicted on them.

There are already standards that regulate the characteristics of bumper beams, and in the future these standards will become even more stringent.

It is known to fix the bumper beam to the structure of the vehicle by generally interposing two shock or energy absorbing boxes (“crashbox” in English).

In known embodiments, these absorber boxes generally consist of deformable elements which are intended to absorb the energy of a frontal impact. However, the assembly thus formed by the bumper beam and the absorber boxes constitutes a heavy and bulky assembly which becomes difficult to accept in modern vehicles which are more and more compact. Also known, from document DE 195 02 307, an energy-absorbing deformation element intended for the protection of a motor vehicle body. This element consists of a bumper which is connected to the side members of the vehicle by means of a housing filled with aluminum foam.

Again, this set is particularly heavy and bulky.

The object of the invention is in particular to overcome the aforementioned drawbacks.

It aims in particular to produce a bumper beam, of the hybrid type, which is capable of being associated with at least one absorber housing to form an assembly having high performance with regard to low weight and reduced bulk.

It is also an object of the invention to propose such a bumper beam which can be easily integrated into a front face of a motor vehicle.

To this end, the invention provides a bumper beam of the type defined in the introduction, which comprises at least one absorber housing integrated into the bumper beam, which is housed at least partly in the open section of the profile and which comprises a envelope suitable for being filled with a metallic foam having energy absorbing properties.

Because the case. absorber occupies at least partially the free volume defined in the open section of the profile, this makes it possible to reduce the size, in particular in the longitudinal direction, of the assembly constituted by the hybrid beam and the absorber housing. It is thus possible, with constant bulk, compared to known solutions, to increase the impact resistance performance.

Conversely, it is possible, by reducing the bulk compared to known solutions, to obtain performances comparable to what was obtained with much more bulky and much heavier assemblies.

In the invention, the profile is advantageously a metal section with a general section in the form of a C or U forming an insert which is overmolded and / or reinforced by a molding material by a technique of hybridization of the material of the profile and of the molding material.

The expression “hybridization technique” is intended to denote any technique which makes it possible to closely associate a molding material, generally a plastic material, with an insert, most often metallic, thus eliminating any fixing or mounting operation. .

Particularly interesting performances are obtained with a steel profile, in particular high elastic limit steel (HLE).

As a molding material, a plastic material advantageously chosen from thermoplastics and thermosetting materials is used, with or without reinforcement. Preferably, the plastic material is chosen from polyamides, in particular polyamide-6, and polypropylenes.

As for the plastic, it is advantageous to reinforce it with an appropriate material, in particular with glass fibers. According to another characteristic of the invention, the molding material forms stiffening ribs in the open section of the profile. This contributes to the mechanical strength of the beam.

The envelope of the absorber housing is advantageously made of a molding material. It is preferably the same material as that defined above for the bumper beam.

However, it is also possible to make this envelope in another material, for example steel.

In a first embodiment of the invention, the envelope of the absorber housing is overmolded and / or connected to the material of the profile. As a result, the material of the envelope is the same as the molding material overmolded on the bumper beam. In such a case, the shell of the absorber box is completely integrated into the bumper beam by hybridization.

In another embodiment of the invention, the envelope of the absorber housing is fixed in the open section of the profile. It follows that the envelope of the absorber housing is not necessarily made of the same molding material as that which is overmolded on the profile.

In this second ι ₍ embodiment of the invention, the envelope of the absorber housing is advantageously integrated into an element ^' of the front face. This means, in other words, that the envelope can be produced with this element of the front face by a molding technique, possibly with hybridization.

Whatever the embodiment, the envelope of the absorber housing is advantageously produced in the form of a hollow section of generally rectangular section, in particular square, which has a first end attached to the bumper beam and a second end suitable for being fixed to the vehicle structure, in particular at the end of a longitudinal beam.

As indicated above, the casing of the housing is capable of being filled, at least in part, with a metallic foam endowed with absorbent properties.

It is advantageous that the casing of the housing is overmolded on this metal foam.

Among the metallic foams that can be used, an aluminum foam, in particular aluminum of the 6000 or 300 series, is preferred.

In the description which follows, given solely by way of example, reference is made to the appended drawings, in which:

- Figure 1 is a view of a bumper beam and absorber housing assembly according to the invention mounted on a front panel module of a motor vehicle; Figure 2 is a partial perspective view of a bumper beam and absorber housing assembly according to a first embodiment of the invention;

- Figure 3 is a longitudinal sectional view of the assembly of Figure 2 showing the attachment of the absorber housing to a front face of a motor vehicle; - Figure 4 is a perspective view of an absorber housing integrated with a front face element in a second embodiment of the invention;

- Figure 5 is a longitudinal sectional view of the assembly of Figure 4, the assembly being equipped with the bumper beam and being fixed to the vehicle structure; and

- Figures 6, 7 and 8 are partial rear views of different bumper beams showing different configurations of stiffening ribs.

In the schematic view of FIG. 1, the element shown comprises a bumper beam 10 constituted by a hollow profile, in the general shape of a C or of a U, in which is housed at least partially an absorber housing 12. It as a result, the overall size L of the assembly in the longitudinal direction of the absorber housing is slightly greater than the length of the absorber housing.

The absorber unit 12 is fixed to the structure of a motor vehicle, here at the end of a lower spar 14, on which is also fixed a front face module 15.

The bumper beam 10 is intended to receive a bumper 17, also called a front shield.

Reference is now made to FIGS. 2 and 3 to describe a first embodiment of the invention.

In this embodiment, the bumper beam 10 is a hybrid beam which integrates the absorber box 12. The beam 10 comprises a section 16 with an open section in the general shape of C. This profile 16, which forms an insert, comprises a generally vertical core 18 extended by two wings, namely an upper wing 20 substantially horizontal and a lower wing 22 substantially horizontal. This profile 16 thus delimits a hollow space in which is housed at least partially the absorber box 12, as seen in Figures 2 and 3.

The profile 16 is advantageously made of steel, in particular of high elastic limit steel (HLE). This steel profile is overmolded and / or reinforced with a molding material

24 which forms an outer coating 26 on the profile and a interior lining 28.

The absorber housing 12 comprises a casing 30 which, in the example, is produced in the form of a hollow section of generally rectangular section bounded by a lower face 32, an upper face 34 and two lateral faces 36. This casing is, in the example, also produced in the same molding material as that which is overmolded on the metal profile.

In this way, the casing 30 and the inner 26 and outer 28 coatings of the profile form an assembly which is molded and integrated into the profile by a hybridization technique.

As shown in Figure 2, the molding material forms stiffening ribs inside the open section of the profile. These ribs here comprise horizontal ribs 35 and vertical ribs 37. Furthermore, horizontal ribs 39 connect the faces 36 of the casing 30.

As illustrated in FIG. 3, the interior of the envelope can advantageously be filled, at least in part, with a metal foam 38 which is, in the example, aluminum foam. As such, aluminum of the 6000 series, for example AA6061, or of the 300 series, for example A356, is advantageously used. Advantageously, the envelope 30 is overmolded on the metal foam 38.

The casing 30 thus has a first end 40 which is housed inside the open section of the profile and a second end 42 which ends in an open face and which is intended to be fixed at the end of a spar 14. To ensure this fixing, advantageously, as shown in FIG. 3, is used a support plate 44 on which two spaced wings 46 depend (only one is visible in FIG. 3) clipping inside the faces 36 of the casing 30. The plate 44 is fixed at the end of the side member 14 by screws 48 which pass through the thickness of the plate 44. Advantageously, the plate 44 traps the core 50 of an element 52 of a front panel module.

In the embodiment of Figures 4 and 5, the casing 30 of the absorber housing 12 is integrated into an element 54 forming part of a front panel module. This element 54 comprises a shaped core 56, from which extends the casing 30 in the form of a profile with a generally rectangular section. This core 56 is extended by different arms, in particular by two upper arms 58 and 60 which will not be described in detail.

The core 56 is pierced with four holes 62 (Figure 5) for its attachment to the end of a profile 14 with the interposition of a fixing plate 44 similar to that described in Figure 3. The element 54 and the envelope 30 of the absorber housing constitute a one-piece assembly produced by a hybridization technique. This element 54 may include a metal insert overmolded by a molding material which forms different parts of the structure and in particular the casing 30.

Thus, when the element 54 is fixed at the end of the spar 14 with the interposition of the plate 44, the absorber box is secured to the spar. FIG. 5 shows, in exploded view, the fixing of the element 54 on the beam 14 with interposition of the plate 44.

The envelope 30 is similar to that of the previous embodiment. It comprises an end 40 which is housed in the open section of the beam and an opposite end 42 which is connected at the end of the beam. However, in this embodiment, the end 42 is made in one piece with the element 54. The beam 12 which comes to cap the end 40 can be fixed to the latter by any suitable means, for example with the interposition of a fixing plate similar to the plate 44 described above.

In the embodiment of Figure 6, the bumper beam 10 has, inside its open section, a housing 68 for receiving the end 40 of the casing 30 of the absorber housing. In this example, the stiffening ribs are oblique ribs 70.

In the embodiment of Figure 7, the interior of the open section of the beam is reinforced by vertical ribs 72.

In the embodiment of Figure 8, there are both horizontal ribs 74 and vertical ribs 76, which cross each other, and which resemble those shown already in Figure 2.

This provides a beam assembly, bumper with absorber which has high performance with regard to its weight and size.

The plastic material used for molding is advantageously a polyamide, in particular polyamide-6, or a polypropylene. This plastic material is advantageously reinforced with glass fibers.

Preferably, therefore, a PA 6 GF 30 or a PP GF 30 is used. The metal profile forming an insert must have an optimized geometry since an optimal inertia of the section is desirable to minimize deflection.

The invention will now be described with reference to the following examples ^• 1 to 3. Examples 1 and 2 are examples comparatives concerning bumper beams not in accordance with the invention, while example 3 relates to a bumper beam according to the invention.

Example 1: steel bumper beam

A steel bumper beam is produced from a closed section profile fixed to the side members of the vehicle, which include conventional absorber boxes.

A so-called "Danner test" is carried out at 16 km / h. The energy absorbed by the beam is 6035 joules and that absorbed by the beams is 4381 joules, which gives a total of

10,416 joules.

As a result, 58% of energy is absorbed by the beam and 42% by the beams which include the absorber boxes. In this example, the weight of the beam is 5.7 kilograms.

Example 2: Aluminum bumper beam with aluminum absorber boxes

A bumper beam is produced from a closed section aluminum profile. This profile is fixed to the side members of the vehicle by means of aluminum absorber boxes. The weight of the beam is 2.7 kg and the two absorber boxes 1.08 kg.

Using the same test as in Example 1, the energy absorbed by the beam is 4100 joules, that absorbed by the absorber boxes 5230, the total being 9330 joules.

Thus, 44% of the energy is absorbed by the beam and 56% by the absorber boxes.

In this example, the dimensions of the absorber box are 130 x 70 x 60 mm (in the X, Y and Z directions). Aluminum is an aluminum of the 7000 series (Re = 300; Rm = 400 Mpa).

Example 3: Hybrid bumper beam with aluminum absorber box

The weight of the beam here is 2.5 kilograms.

The bumper beam is here in accordance with the invention. Using the Danner test, under the same conditions as above, the energy absorbed by the beam is 1320 joules, that absorbed by the absorber box is 8040 joules, that absorbed by the ribs by 240 joules, the total being 9600 joules.

As a result, 16% of the energy is absorbed by the beam insert, and 84% by the absorber boxes.

In this example, the dimensions of the absorber box are 190 x 60 x 70 mm (in the X, Y and Z directions). Aluminum is an aluminum from the 6000-7000 series.

To reach the same level of absorption as an aluminum beam, with the same weight, it is advantageous to have a larger absorber box: 190 mm are necessary to absorb 9600 joules.

In the invention, the thickness of the metal insert can vary between 0.7 and 1.2 mm depending on the characteristics of the steel. A 0.77 mm thick HLE steel is preferably used (Re = 360 Mpa; Rm =, 450 Mpa; A% = 21).

The following table summarizes the figures given above for examples 1 to 3.

In the invention, an aluminum foam of different densities can be used. The beam with absorbent boxes filled with aluminum foam absorbs 1.6, 2.5 and 3 times more energy than the beam alone for densities of 0.2, 0.3 and 0.4 g / cm respectively ³ .

For the same energy (5000 joules), the intrusion is reduced by 37%, 50% and 58% for densities of 0.2, 0.3 and 0.4 g / cm ^{3 respectively} .

Thus, the use of aluminum foam makes it possible to reduce either the length of the absorber housing or its section.

The invention thus finds an application to motor vehicles.

Claims

claims

1. Bumper beam, in particular for a front face of a motor vehicle, said beam being formed of a hybrid material and comprising an open section profile, characterized in that it comprises at least one integrated absorber housing (12) to the bumper beam (10), and in that said absorber housing is housed at least partially in the open section of the profile (16) and comprises a casing (30) capable of being filled with a metallic foam (38 ) having energy absorbing properties.

2. Bumper beam according to claim 1, characterized in that the profile (16) is a metal profile with a general section in the form of a C or U forming an insert which is overmolded and / or reinforced by a molding material (24 ) by a technique of hybridization of the profile material and the molding material.

3. Bumper beam according to claim 2, characterized in that the profile (16) is made of steel, in particular of high elastic limit steel (HLE).

4. Bumper beam according to one of claims 2 and 3, characterized in that the molding material (24) is a plastic material chosen from thermoplastics and thermosetting materials, with or without reinforcement.

5. Bumper beam according to claim 4, characterized in that the plastic material is chosen from polyamides, in particular polyamide-6, and polypropylenes.

6. Bumper beam according to one of claims 4 and 5, characterized in that the plastic is reinforced, in particular by glass fibers.

7. Bumper beam according to one of claims 2 to 6, characterized in that the molding material (24) forms stiffening ribs (35, 37, 39, 70, 72, 74, 76) in the section open profile.

8. Bumper beam according to one of claims 1 to 7, characterized in that the casing (30) of the absorber housing (12) is made of a molding material.

9. Bumper beam according to claim 8, characterized in that the casing molding material (30) is as defined in one of claims 4 to 6.

10. Bumper beam according to one of claims 8 and 9, characterized in that the casing (30) of the absorber housing is overmolded and / or connected to the material of the profile.

11. Bumper beam according to one of claims 8 and 9, characterized in that the casing (30) of the absorber housing

(12) is fixed in the open section of the profile (16).

12. Bumper beam according to claim 11, characterized in that the casing (30) of the absorber housing (12) is integrated in an element (54) of the front face.

13. Bumper beam according to one of claims 8 to 12, characterized in that the casing (30) of the absorber housing (12) is a hollow profile of generally rectangular section, in particular square, which has a first end ( 40) attached to the bumper beam (10) and a second end (42) suitable for being fixed to the structure of the vehicle, in particular at the end of a longitudinal beam (14).

14. Bumper beam according to one of claims 1 to 13, characterized in that the casing (30) of the absorber housing (12) is molded onto the metal foam (38).

15. Bumper beam according to one of claims 1 to 14, characterized in that the metal foam (38) contained in the casing (30) of the absorber housing is an aluminum foam.

16. Bumper beam according to claim 15, characterized in that the metal foam (38) is made of aluminum of the 6000 or 300 series.