FR2962390A1 - Shock absorber i.e. bumper, for use in automobile, has cells delimited by side walls and internal ribs forming body to ensure absorption of shocks along main direction and extrusion direction perpendicular to main direction - Google Patents

Abstract

The absorber (1) has a body (4) delimiting cells (6). The body is obtained by extrusion along extrusion direction (3). The cells are delimited by external side walls (10a, 10b) and internal ribs (11, 12) forming the body, so as to ensure absorption of shocks along main direction (2) and the extrusion direction that is perpendicular to the main direction. The internal ribs are arranged longitudinally and oriented along the main direction, where the ribs are shifted from one another. The absorber made of plastic or composite material. An independent claim is also included for a method for realizing a shock absorber.

Description

The technical sector of the present invention is that of shock absorbers, which can be used for example for a vehicle bumper. In the field of shock absorption, it is known to insert in an mechanical chain an absorber, offering less resistance to deformation in order to absorb the greater part of the impact energy, and thus protect others elements of said chain. Thus, in the automotive field a shock absorber is typically disposed between the outer shield or bumper and the chassis of the vehicle. Different principles of deformable elements are possible the absorber can be elastic or plastic. Patents FR-2932445, FR-2926270, FR-2870802 and KR20080093630 describe examples of shock absorbers.

Given the significant energy to be absorbed in the most critical case of an automobile during a frontal impact and available volumes, the existing absorbers are most often made of steel and are therefore heavy. The present invention overcomes this disadvantage by allowing, by means of a suitably adapted structure, in a volume that remains reasonable, to achieve an absorber of light alloy or even plastic or composite material. The invention relates to a shock absorber intended to equip a vehicle, characterized in that it is in the form of a body delimiting cells and obtained by extrusion in an extrusion direction, the cells being delimited by the outer side walls and internal ribs forming the body, the structure providing shock absorption in a main direction, the extrusion direction being substantially perpendicular to the main direction. According to a feature of the invention, the body has an outer shape regularly decreasing in thickness and / or width from a front end to a rear end, for example substantially triangular. According to another characteristic of the invention, the body has an outer shape regularly constant in thickness and / or width from a front end to a rear end, for example substantially rectangular. According to yet another characteristic of the invention, the impact resistance of the body is expected to increase from the front end to the rear end. According to yet another characteristic of the invention, the absorber comprises internal ribs disposed longitudinally and oriented in the main direction, said ribs being offset from one cell to the other. According to yet another characteristic of the invention, the body has a stepped shape delimiting a succession of blocks, the width and / or thickness of each of which is increasing from front to rear.

According to yet another feature of the invention, the absorber comprises at each of its front and rear ends a shoulder for fixing the absorber on the vehicle. According to yet another characteristic of the invention, the absorber comprises an integral protrusion of the rear shoulder adapted to engage a vehicle spar. According to yet another characteristic of the invention, the absorber is sized to absorb a high energy shock to form a first stage, and is assembled in series, aligned in the main direction, with at least a second stage constituted by a second absorber sized to absorb a low energy shock. The invention also relates to a method for producing a shock absorber, characterized in that it comprises the following steps: extrusion of a honeycomb structure in a main direction using a plastic type material or aluminum, - cutting said cellular structure in a main direction substantially perpendicular to the extrusion direction to obtain absorbers. Advantageously, the cut is made along a section line defining absorbers having a symmetry with respect to a plane perpendicular to the extrusion direction. Advantageously, the section line defines absorbers arranged head to tail and alternated, without scrap of honeycomb structure. Advantageously, the cut is made consistently, triangular or staged. An advantage of the present invention is that an absorber is easily manufactured and low cost compared to the complex embodiments of the prior art. Another advantage of the invention lies in the simultaneous production of several absorbers. Yet another advantage of the invention lies in obtaining homogeneous characteristics of the absorbers whose absorption energy is identical for the same batch of absorbers, hence an absence of imbalance between two absorbers. The invention thus offers the skilled person the ability to size an absorber according to the degree of absorption that it wishes to adopt by varying the thickness of the material used, the length and the number of ribs, the number of cells and their distribution throughout the absorber, allowing it to easily achieve the desired results. Other characteristics, details and advantages of the invention will emerge more clearly from the detailed description given below as an indication in relation to drawings in which: FIG. 1 presents in a perspective view an embodiment of a According to the invention, FIG. 2 represents an embodiment of a two-stage compound absorber, FIG. 3 represents in perspective another embodiment of the absorber, FIG. 4 represents a longitudinal section of FIG. 3, FIGS. 5a-5c each illustrate one embodiment of the cutting step, FIG. 6 shows an embodiment of the absorber, FIG. 7 illustrates a particular use of the absorber, FIG. FIG. 8 shows an absorber in straight cut, FIG. 9 is an offset cut-off absorber, FIGS. 10 and 11 show other embodiments. Figure 12 shows an assembly of two absorbers, and Figure 13 shows the mounting of an absorber assembly on a vehicle. In Figure 1, there is shown a view of the shock absorber 1 according to a first embodiment of the invention. This absorber 1 is designed to absorb a shock applied mainly in a main direction F2. The absorber 1 is in the form of a honeycomb body 4 delimiting a prismatic set with a rectangular base. This body 4 is delimited by a front face 8, a rear face 9 and side walls 10a and 10b. The rear face 9 is provided with a shoulder 13 projecting from both sides. The body 4 encloses a plurality of internal ribs 11, 12 perpendicular to each other delimiting cells. The ribs 11 are arranged parallel to the side walls 10a and 10b and the ribs 12 perpendicular to said side walls. In the figure, it can be seen that the body 4 consists of a succession of blocks 4a to 4f. Block 4a comprises a rib 11a, the body 4b two ribs 11b and 11c, and so on. However, the number of ribs 11 can be increasing from block 4a to block 4f. 6 blocks are represented here, but it goes without saying that this number can be reduced or increased according to the performances desired by those skilled in the art. The shapes of both the outer frame 10 and the internal ribs 11, 12 may be arbitrary, the extrusion embodiment depending essentially only on the shape of the die, and the latter being little influenced by constraints related to the method of manufacture. The body 4 can be made by any means. However, it is preferred to carry out this structure by extrusion through a die. Therefore, according to the invention, a profiled honeycomb structure is preferred, reproducing itself equal to a rectilinear translation along an extrusion direction 3 or F3 as explained below. Such an embodiment advantageously allows low cost production since it is possible to achieve in a single pass an advantageously even number of absorbers. By the present document is meant by extrusion any manufacturing method in which the manufacturing uses a die through which the material is constrained in order to produce a profile. Thus, the extrusion includes extrusion itself and pultrusion, both techniques being applied to any type of materials. The honeycomb body 4 is profiled according to a generatrix or extrusion direction F3. The absorber 1 is characterized in that the cellular body 4 is used so that the deformation of the cells according to their profile achieves the progressive absorption of the impact energy. For this, the generator of the profile or extrusion direction F3 is disposed substantially perpendicular to the main direction F2 of the shock. According to a characteristic of the invention, the absorber 1 has a trapezoidal prismatic shape in section whose sides are of greater relative extension in the main direction F2 than the bases. The absorber 1 is thus elongated mainly in the main direction 2 or F2 which corresponds to the direction of application of the shock to be absorbed. The shock absorber 1 is advantageously designed such that its section, in a plane perpendicular to the main direction 2, is substantially increasing from the face 8 or small base to the face 9 or large base. This growth can be strict or not, regular or not, staged or not. The general shape of the absorber can thus be pyramidal, regular or stepped with portions of constant section where appropriate. The resistance to deformation of the absorber 1 is substantially increasing with the dimensions of a section in a plane perpendicular to the main direction F2. The desired effect is to spatially and progressively distribute the deformation during an impact, from the front or small base 8 which will first be deformed to the large base 9. The small base 8 will therefore initially absorb the shock and the large base will eventually be deformed last after deformation or progressive destruction of the entire honeycomb body 4 along the main direction 2.

The gradual variation of the outer shape of the cellular body 4 can be obtained in different ways by playing on the one hand on the profile of the extrusion and on the other hand on the shape of the cut. One way is a gradual variation of the extrusion section 5 (section in a plane perpendicular to the extrusion direction 3). Another way consists of a progressive variation, in the same direction, of the transverse section 7 (section along a plane containing the main direction 2 and the extrusion direction 3). The extrusion section 5 is thus perpendicular to the transverse section 7. The extrusion section 7 may have an external shape regularly decreasing from one end 9 to the other 8. This outer shape may, for example, be triangular.

The extrusion section 5 and the transverse section 7-7 can contribute to this progressive decay. According to an alternative embodiment which has other advantages which will be described later, only the transverse section 7-7 has such a progressive decay, and the extrusion section 5-5 defines a substantially prismatic body 6 with a rectangular base. Thus, the extrusion section 5-5 has a constant dimension in a direction perpendicular to the main direction 2. Under this condition, the extrusion section 5 may be symmetrical with respect to a plane perpendicular to the main direction 2. Also , a great freedom is left to a designer of alveolar body profile 4 based on the aforementioned explanations. This designer can thus determine said extrusion section 5 as a function of the desired impact resistance. Thus, this resistance can be obtained at leisure by varying the relative thickness or thickness of material, the number, the sizes and relative provisions of the ribs 11, 12 and the frame 10. Very many configurations are thus possible. It is thus possible to vary the extrusion section 5 at will of an absorber 1 in order to withstand a given impact force according to a desired deformation kinematics. According to an advantageous characteristic of the absorber, the cellular body 4 is deformed by progressive destruction of the cells and / or the outer frame 10 and / or ribs 11, 12, in the direction of the main direction 2, preferably a folding or any other deformation where the structure moves away from said main direction 2. In order to contain at most said deformation along said main direction 2, the configurations where the extrusion section 5 is symmetrical relative to the main direction 2, due to a dual symmetry of the forces under the effect of a shock in the main direction 2, are advantageous. It is the same for configurations where the transverse section 7 is symmetrical relative to the main direction 2. Overall, it is advantageous that each block 4a-4f of the absorber in a plane perpendicular to said main direction 2 is relatively symmetrical at said main direction 2. Various design rules of the honeycomb body 4 can improve the deformation behavior.

According to another embodiment, the cellular body 4 and its extrusion section 5 comprises 6 rectangular cells. Such an embodiment advantageously allows easy manufacture of the corresponding die. Whatever the configuration of the cells, they reveal internal ribs 11, 12 in different orientations from the small base 8 to the large base 9. Depending on this orientation, a rib 11 or 12 has a different role when a deformation of the alveolar body 4 under the effect of a shock on the small base 8 to absorb. Thus, the internal ribs can be classified as longitudinal ribs 11 when their orientation is closer to the main direction 2 until it becomes parallel and classified as transverse ribs 12 when their orientation is further away from the main direction 2 to him become perpendicular. The role of the longitudinal ribs 11 is to transmit the shock force. On the contrary, the role of the transverse ribs 12 is to be deformed, if necessary until destruction, in order to dissipate the energy of the shock. Also, according to another advantageous configuration of the extrusion section 5, the longitudinal ribs 11 are arranged in staggered rows. On the contrary, and mainly at the crossing of a transverse rib 12, between a first cell and the adjacent cell, the longitudinal ribs 11 are offset. Thus, during the deformation, there is a shear of a transverse rib 12 by the longitudinal ribs 11 located on either side of the transverse rib 12. For this purpose so that the longitudinal ribs 11 resist and transmit the forces and that the transverse ribs 12 deform, it may be advantageous to make the longitudinal ribs 11 with a thickness greater than that of the transverse ribs 12. It may also be advantageous to introduce a thickness variation of the ribs 11 from the base 8 at the base 9. Thus, the rib 11a may be less thick than the ribs lib and lic which themselves will be less thick than the following and so on. The absorber 1 can be used on a vehicle to dampen shocks on the front or rear bumpers.

The shoulder 19 allows the attachment of the absorber 1 on the appropriate part of the chassis of a vehicle, for example by screwing. Said shoulder 19 is advantageously wide enough to distribute any residual force transferred to the vehicle. It goes without saying that the shoulder 19 is advantageously made simultaneously with the honeycomb body 4 and in the same material. The absorber 1 can be made of any material that can be extruded. Depending on the range of shock force to be absorbed, the absorber 1 may be made of plastic material, possibly reinforced by fibers (pultrusion) or a metallic material, such as aluminum or a light alloy of it. Due to the differences in the range of forces implemented as explained above, it is more difficult to design a single absorber 1 able to deform and dissipate the energy correctly in both ranges. In some cases of application of such an absorber 1, and particularly that of an automobile bumper, the absorber 1 is generally subjected to several ranges of shocks. Thus, an automobile bumper is designed to receive a shock of high energy, such as that caused by a frontal impact at high speed (> 75 km / h), but also low energy shocks such as those caused by shocks of the type. low speed urban traffic (<15 km / h). A shock of low energy is more frequent and it is a pity that it comes to damage the front part or back of the vehicle which it is then necessary to replace. The embodiment of the invention illustrated in FIG. 2 makes it possible to answer this problem. The absorber thus consists of two absorbers 14, 15 of similar structure to that of the absorber described in connection with Figure 1. These absorbers 14 and 15 are made individually and are then assembled with a connecting element 17. These absorbers The two absorbers 14, 15 are arranged in series, aligned in such a way that their respective main direction 2 is confused. The first absorber 14 is dedicated to the absorption of low energy shocks. The second absorber 15 is dedicated to the absorption of high energy shocks. Thus when the compound absorber undergoes only a low energy shock, the latter is absorbed by the first absorber 14 which deforms and absorbs the shock thus protecting the other organs of the vehicle. The second absorber 15 is thus spared and does not suffer damage. In this case, only the first absorber 15 is replaced.

It goes without saying that one can realize an absorber comprising several stages. Each stage may comprise several absorbers 14a, 14b, 14c, ... to absorb a range of shock effort increasing. In the case of application to a bumper, the absorber 14 may be made of aluminum with a length of about 60 cm in the main direction, being adapted to absorb a high-energy frontal impact. The second stage 15 may be made of plastic material for a length less than that of the absorber 15.

In Figure 3, there is shown by way of example another embodiment of the absorber. The body 4 comprises five delimited blocks 4a, 4b, 4c, 4d and 4e in this figure whose width 11 at the front AV is increasing towards the width 12 at the rear AR.

The block 4a has three horizontal ribs in the plane of the figure, the block 4b four ribs, the block 4c three ribs, the block 4d four ribs and the block 4e three ribs. It goes without saying that depending on the desired absorption effect, it is possible to vary the number of blocks, the number of horizontal ribs and their thickness in each block, the thickness of the vertical ribs, etc. For example, it is possible to provide a number of ribs increasing from the front to the rear of the absorber. It is also possible to provide an increasing thickness of the vertical ribs from front to rear. A junction shoulder 18 is provided integral with the front block 4a and another junction shoulder 19 is integral with the rear block 4e as will be explained below.

In FIG. 4, the absorber of FIG. 3 is shown in section, the same elements having the same references. For example, considering block 4b, the thickness e1, e2, e3 and e4 of the various horizontal ribs 11 can be adjusted according to the result sought by those skilled in the art. It is the same vertical ribs 12 él-é5. Considering the blocks 4a and 4d, we see that the drop La is less than the width Ld. It is easily understood that by varying the number of blocks, the widths 1 and L of these blocks, the number of ribs 11 and 12, the thickness (e) of these ribs, different configurations are possible depending on the effect terminal sought. It is also understood that the shock resistance of the absorber must increase progressively from front to rear. Thus, during an impact, the block 4a is first destroyed, then the block 4b, and so on. The manufacture of the absorber 1 according to the invention is advantageous in that it implements a simple method, because of the simplicity of the structure of said absorber 1. This method is explained in connection with Figures 5a-5c. This method comprises a first step of manufacturing, preferably by extrusion, a honeycomb structure 40. Here a die can be used. The shape of this die is defined by the extrusion section 5. During a second step, said honeycomb structure 40 is cut in a direction perpendicular to the extrusion direction 3 and the main direction 2. The cut corresponds to to the transverse section 7 that it allows to achieve. Thus, the honeycomb structure 40 can be extruded according to a profile. Said section is then cut to produce absorbers 1. Such a method is simple and allows an efficient industrial implementation. However, such a symmetry advantageously makes it possible, as illustrated in FIG. 5a, to cut off absorbers 1, 1a and 1b, for example, head-to-tail and alternated in the cellular body 40, according to a cutting plane schematized by the reference 16. This advantageously allows to use almost all of the profile of said cellular structure 40, without loss of material or waste important. FIG. 5b shows another honeycomb structure 50 in which the absorbers la'-1f 'equipped with the joining shoulders 18 and 19 have been cut. According to this embodiment of the structure 50, the absorbers 1 are cut back to back and alternated. The absorbers 1 obtained from the cellular structures 40 and 50 are of rectangular pyramidal shape whose bases have an identical dimension respectively corresponding to the thicknesses E40 and E50 of these structures. Each absorber then has an outer shape regularly decreasing in width and consistent in thickness from a front end to a rear end. It goes without saying that the outer shape of the absorber could be decreasing in width and constant thickness without changing its absorption characteristics. FIG. 5c illustrates the production of another honeycomb structure 60 for cutting the "-ld" absorbers, each equipped with a front junction shoulder 18 and a rear junction shoulder 19. Although the number of absorber is less than that obtained according to FIGS. 5a and 5b, this embodiment makes it possible to produce absorbers of decreasing dimension in both directions, that is to say in thickness and in width.

The front bases are arranged along the same face 61 of the honeycomb structure 60 and the rear faces are on the same face 62 of this structure 60. The absorbers 1 obtained from the honeycomb structure 60 are of rectangular pyramidal shape, but of which the bases are of different sizes. Indeed, here the thickness E'60 is less than the thickness E "60. Each absorber 1 then has an outer shape regularly decreasing in width and thickness from a front end to a rear end.

FIG. 6 shows another embodiment of the absorber 1 comprising the body 4 as previously obtained in connection with FIG. 5c, to which is attached a front shoulder 18 integral with the front face and a rear shoulder. 19 secured to the back side. In this configuration, the body 4 has been cut in a triangular manner. The dimensions of the body 4 are decreasing in both directions, in thickness and in width, from front to rear. This rear shoulder 19 is extended by an outgrowth 20 which is intended to be fitted into the longitudinal member of the vehicle abutting against the rear shoulder 19. The front shoulder 18 is intended to receive the vehicle bumper fixing means . In this figure 6, the absorber 1 is shown in the mounting direction on the vehicle. It is seen that the ribs 11 are substantially horizontal in the plane of the figure and the ribs 12 are vertical. According to this embodiment, the small and large bases of the body 4 are of square shape. In Figure 7, there is shown the absorber 1 of Figure 6 but in another direction of mounting on the vehicle. We see that according to this arrangement, the ribs 11 are in a substantially vertical plane, the ribs 12 then being arranged also vertical but perpendicular to the previous one. FIG. 8 shows another alternative embodiment of the absorber 1 according to which the body 4 has been cut in a constant manner in thickness and in width, that is to say that the lateral faces are of rectangular shape. . Only the upper face S is visible in this figure. The body 6 is in this case of parallelepiped shape. The front shoulders 18 and rear 19 and the protrusion 20 are also of parallelepipedal shape. FIG. 9 shows another alternative embodiment of the absorber 1 according to which the body 4 has a stepped cut in the width, delimiting a succession of trapezoidal prismatic blocks or stages 4a, 4b, 4c, etc. 4i , whose width (1) of each is increasing. These blocks 4a-4i have a decreasing thickness linearly in the thickness. As a result, the shock resistance of the absorber 1 increases from front to rear. It goes without saying that the skilled person will be able to calibrate these different blocks according to the desired progressive resistance of the absorber depending on the vehicle. Each block is sized to absorb a specific part of the shock energy. Thus, if dimensions are dimensioned more and more resistant from the shoulder 18, the absorber is given a gradual absorption of shock energy with a destruction of the blocks of the weakest resistance to the most robust.

FIG. 10 shows another embodiment of the absorber whose body 4, consisting of the elementary bodies 4a-4f, is cut stepped in the thickness (e) and whose width (1) is linearly decreasing. from front to back.

In Figure 11, there is shown another embodiment of the absorber whose body 4 is also constituted by the blocks 4a-4f. We see that here the absorber is staged in both directions, according to the thickness (e) and the drop (1). Block 4a has a width and a thickness both lower than those of block 4b, and so on. In Figure 12, there is shown an absorber assembly according to the invention for use on a vehicle (not shown). Each of the absorbers 1a and 1b conforms to that shown, by way of example, with reference to FIG. 5. For this purpose, two absorbers 1a and 1b are fixed to each other by means of a cross member 21 whose shape is adapted to that of the vehicle. This crossbar is fixed on the shoulders 18 of each absorber by appropriate means for example by gluing, screwing, riveting, welding, etc. This assembly is completed by the addition of a second absorber stage 22a and 22b consisting of a body 23 and a sole plate 24 itself fixed to the cross member 21. It can therefore be seen that this configuration corresponds to that described In other words, the absorbers 1a and 1b absorb the large shocks and the absorbers 22a and 22b absorb light shocks. Figure 13 illustrates the integration of the assembly described in relation to Figure 9 in a vehicle of which only the deck 23 is shown. In this figure, it can be seen that each protrusion 20 (not visible in the figure) is engaged in the corresponding spar thus allowing the assembly to be secured to the vehicle.

Claims (13)

REVENDICATIONS1. Shock absorber (1) intended to equip a vehicle, characterized in that it is in the form of a body (4) delimiting cells (6) and obtained by extrusion in an extrusion direction (3), the cells (6) being delimited by the external lateral walls (10a, 10b) and internal ribs (11, 12) forming the body (4), the structure providing shock absorption along a main direction (2), the direction extrusion device (3) being substantially perpendicular to the main direction (2). 2. Shock absorber (1) according to claim 1, characterized in that the body (4) has an external shape regularly decreasing in thickness and / or width from a front end (8) to a rear end (9). , for example substantially triangular. 3. Shock absorber (1) according to claim 1, characterized in that the body (4) has an outer shape regularly constant in thickness and / or width from a front end (8) to a rear end (9). , for example substantially rectangular. 4. shock absorber (1) according to one of claims 2 or 3, characterized in that the impact resistance of the body (4) is provided increasing from the front end (8) to the rear end (9) . 5. Absorber shock (1) according to any one of the preceding claims, characterized in that it comprises internal ribs (11) arranged longitudinally oriented in the main direction (2), said ribs (11) being offset from one cell to another. 6. Shock absorber (1) according to claim 1, characterized in that the body (4) has a stepped shape delimiting a succession of blocks (4a, 4b, 4c, 4i), the width (1) and / or the thickness (e) of each is increasing from front to back. 7. Shock absorber (1) according to any one of claims 1 to 6, characterized in that it comprises at each of its front and rear ends a shoulder (18, 19) for fixing the absorber on the vehicle. 8. shock absorber (1) according to claim 7, characterized in that it comprises an outgrowth (20) integral with the rear shoulder (19) adapted to engage in a longitudinal member of the vehicle. 9. Shock absorber (1) according to any one of claims 1 to 8, characterized in that it is sized to absorb a high energy shock to form a first stage (1, 14), and in that it is assembled in series, aligned in the main direction (2), with at least a second stage (15) constituted by a second absorber (15, 22) sized to absorb a low energy shock. 10. A method of producing a shock absorber (1), according to any one of the preceding claims, characterized in that it comprises the following steps: - extrusion of a cellular structure (40, 50, 60) according to a main direction (3) using a material of plastic or aluminum type, - cutting of said cellular structure (40, 50, 60) in a main direction (2) substantially perpendicular to the extrusion direction (3 ) to obtain absorbers. 11. The method of claim 10, characterized in that the cut is performed along a cutting line (16) defining absorbers having a symmetry with respect to a plane perpendicular to the extrusion direction. 12. The method of claim 11, characterized in that the section line defines absorbers arranged head and tail alternately, without scrap structure alveolar (40, 50, 60). 13. The method of claim 10, characterized in that the cut is made consistently, triangular or stepped.