Shock absorber with two composite inserts

Abstract

The invention relates to a shock absorber (2) for a motor vehicle, the shock absorber comprising at least one plastic casing (14) and a first composite insert (18), characterised in that the shock absorber (2) comprises at least one additional composite insert (20) that is arranged against the first composite insert (18) with at least one connecting region (52) between the first composite insert (18) and the additional composite insert (20) so as to form a reinforcing assembly (16), the first composite insert (18) and the additional composite insert (20) being arranged on either side of a connecting plane (P) in which the at least one connecting region (52) extends, the plastic casing (14) surrounding the reinforcing assembly (16).

Description

[0001] DESCRIPTION

[0002] TITLE: SHOCK ABSORBER WITH TWO COMPOSITE INSERTS

[0003] The present invention relates to the fields of mechanics and passive safety of motor vehicles and it relates more particularly to shock absorbers used to absorb the forces undergone, in particular axial forces, by a motor vehicle during a high-speed impact.

[0004] In order to limit the damage that a motor vehicle and its occupants may suffer in the event of a collision, it is known to equip these vehicles with both active safety devices, which aim in particular to avoid collisions, and passive safety devices, which aim to reduce the intensity of the impact suffered. Thus, motor vehicles are conventionally equipped with shock absorbers, in particular on the front or rear of the vehicle, which are configured to absorb the kinetic energy released during frontal collisions and which thus make it possible to limit the damage that these collisions can cause for users and for the structure of the vehicle itself.

[0005] Nowadays, it is known to make these shock absorbers in bi-material, and no longer only in aluminum or steel. These bi-material shock absorbers can notably have a plastic casing housing an insert made of composite material. More specifically, the insert has a profile as well suited as possible to the absorption of axial forces and the plastic material is injected around this composite profile to ensure the absorber holds during small impacts.

[0006] Bi-material shock absorbers known from the state of the art may require a significant portion of plastic material, in particular due to an open profile of the composite insert, for example S-shaped, which requires filling the openings induced by this type of profile with plastic material in order to stabilize the insert within the plastic casing partly constituting the shock absorber. In addition to the cost price of the shock absorber which may be impacted by the massive injection of plastic material, the plastic material of the casing has the disadvantage of being brittle at low temperatures, which implies a loss of stability of the shock absorber in these extreme conditions so that the quantity of composite material must be controlled it is then interesting to reduce its quantity and to balance this reduction by an addition of composite material.

[0007] The present invention falls within this context and proposes a shock absorber for a motor vehicle, comprising at least one plastic casing and a first composite insert, characterized in that the shock absorber comprises at least one additional composite insert which is arranged against the first composite insert with at least one junction zone between the first composite insert and the additional composite insert so as to form a reinforcement assembly, the first composite insert and the additional composite insert being arranged on either side of a junction plane in which the at least one junction zone extends, the plastic casing surrounding the reinforcement assembly.

[0008] The addition of an additional composite insert increases the portion of composite material in the general configuration of the shock absorber and makes it possible to simply generate a composite insert profile, i.e. here a profile of the reinforcement assembly, which may have closed areas not to be filled with the plastic material when injecting the latter. More particularly, bringing the first composite insert and the additional composite insert into contact via one or more junction areas can make it possible to create areas, within the reinforcement assembly formed by these two inserts, which are closed in a given section plane, and this generates fewer areas to be filled with plastic material than when a single composite insert is used.

[0009] This allows both to reduce the quantity of plastic material needed to cover the inserts and to limit the fragility of the assembly in the event of low temperatures and this can allow the creation of hollow zones within the shock absorber, between the two inserts forming the reinforcement assembly, which generates a shock absorber that is lighter and less expensive but just as effective since the quantity of composite material is significant.

[0010] According to an optional characteristic of the invention, the first composite insert and the additional composite insert each comprise at least one curved portion.

[0011] The curved portions help to stabilize the insert during its deformation. Each curved portion is considered here in a plane perpendicular to the axial direction of the force that the shock absorber must absorb in the event of a frontal collision. In other words, for a shock absorber arranged on the front or rear face of the vehicle and which must absorb a longitudinal axial force, each curved portion is considered in a vertical and transverse plane, perpendicular to the longitudinal direction. These curved portions can in particular delimit the junction zones between the first composite insert and the additional composite insert and allow the formation of hollow bodies.

[0012] According to an optional characteristic of the invention, different discontinuous junction zones are formed in the junction plane between the first composite insert and the additional composite insert, the curved portions participating in forming at least one hollow body arranged between two junction zones, the junction plane passing through said hollow body.

[0013] In other words, the first composite insert and the additional composite insert have curved portions that are arranged opposite each other so as to form one or more hollow bodies when these two inserts come into contact with each other, each hollow body being delimited by a closed profile defined by the two curved portions joined to each other and arranged on either side of the joining plane. It is understood here that at least two joining zones delimit a hollow body. Each hollow body is defined by curved portions which contributes to the stability of the insert during its deformation under stress and each hollow body has a closed profile which makes it possible to generate a space in the general structure of the shock absorber which cannot be filled by the plastic material, so that less plastic material is used for the formation of the shock absorber.

[0014] Furthermore, it should be noted that the hollow body, in addition to its structural characteristics mentioned above and in more detail below, can allow the implementation of accessories, such as a tow hook for example.

[0015] According to an optional characteristic of the invention, the first composite insert and the additional composite insert are symmetrical to each other with respect to the junction plane.

[0016] Such a feature makes it possible to provide reinforcement assemblies of complex shape, with a plurality of hollow bodies and curved portions, which are produced by assembling two standardly produced parts against each other, one of the parts being turned over to come against the other part before injection of the plastic material. This facilitates the manufacturing process.

[0017] According to an optional feature of the invention, the plastic envelope has two longitudinal end faces and lateral faces, the longitudinal end faces and the lateral faces being made of plastic material.

[0018] According to an optional feature of the invention, the side faces comprise a network of ribs.

[0019] The network of ribs is configured to give rigidity to the plastic envelope, and therefore ensure the retention of the composite inserts, by limiting the quantity of plastic material used.

[0020] According to an optional characteristic of the invention, the two longitudinal end faces comprise at least one opening arranged opposite a hollow body formed by the junction of the first composite insert and the additional composite insert.

[0021] In other words, the opening is arranged longitudinally, that is to say in the direction of the axial force released by the potential collision to be suffered by the vehicle and the shock absorber, in the extension of the hollow body formed by the junction of the two inserts, in the junction plane. The opening makes it possible in particular to lighten the structure of the plastic envelope and to make savings in plastic material over the entire shock absorber.

[0022] According to an optional characteristic of the invention, the hollow body is formed by at least one curved portion of the first composite insert and / or the additional composite insert having a radius of curvature of between 1 and 10 times the thickness of said composite insert. Preferably, the radius of curvature is between 2 and 5 times the thickness of the composite insert. For example, it may be of the order of 5 millimeters.

[0023] According to an optional characteristic of the invention, the first composite insert and the additional composite insert each have a profile formed of curved portions and flat portions forming the junction zones, said profile extending between a first free end and a second free end, the free ends being perpendicular to the junction plane.

[0024] According to an optional characteristic of the invention, the first composite insert and the additional composite insert are arranged against each other, forming two junction zones between the first composite insert and the additional composite insert which are discontinuous and separated by a single hollow body, each of the junction zones extending in the vicinity of one of the free ends.

[0025] As mentioned, the free ends of each insert extend perpendicular to the joining plane and the free end of one of the two inserts joins at the corresponding free end of the other insert to initiate the joining zone. The reinforcement assembly comprises a single hollow body which generates a discontinuity between a first joining zone and a second joining zone.

[0026] According to an optional characteristic of the invention, the first composite insert and the additional composite insert comprise free ends which extend substantially parallel to the junction plane and which form one of the junction zones, the reinforcement assembly comprising at least one hollow body generating a discontinuity between two junction zones.

[0027] The invention also relates to a motor vehicle characterized in that it comprises a shock absorber as previously mentioned and a cross member, the shock absorber being interposed between the cross member and a fixing interface of the motor vehicle.

[0028] The invention also relates to a method for manufacturing a shock absorber as previously mentioned, during which the first composite insert and the additional composite insert initially presented in planar form are preheated before placing them in an injection tool, the first composite insert and the additional composite insert are preformed in the injection tool by creating curved portions, while retaining planar contact walls intended to be pressed against each other to form junction zones, the first composite insert and the additional composite insert are assembled by pressing their contact wall against each other when the injection tool is closed, plastic material is injected around the reinforcement assembly formed by the junction of the first composite insert and the additional composite insert once the injection tool is closed.

[0029] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and examples of embodiment given for informational and non-limiting purposes with reference to the appended drawings on the other hand, in which:

[0030] [Fig. i] is a perspective view of a bumper assembly comprising a shock absorber according to the invention;

[0031] [Fig. 2] schematically illustrates a perspective view of a shock absorber according to the invention;

[0032] [Fig. 3] schematically illustrates a first embodiment of a shock absorber according to the invention with, side by side, a perspective view of the shock absorber as a whole, a view in the same perspective of a first composite insert and an additional composite insert forming, according to the invention, a reinforcement assembly within the shock absorber and a front view illustrating a section of these two inserts;

[0033] [Fig. 4] schematically illustrates a second embodiment of a shock absorber according to the invention with a representation similar to that of Figure 3, the shock absorber according to the second embodiment being similar to that illustrated in Figure 2;

[0034] [Fig. 5] schematically illustrates a third embodiment of a shock absorber according to the invention with a representation similar to that of Figures 3 and 4; and

[0035] [Fig. 6] schematically illustrates different successive stages of a method of manufacturing a shock absorber according to the invention.

[0036] The features, variants and different embodiments of the invention may be combined with each other in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be conceived comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from the state of the prior art.

[0037] In the figures, elements common to several figures retain the same reference.

[0038] In the figures, the names longitudinal, transverse, vertical, horizontal, left, right, upper, lower, front and rear refer to the orientation, in a trihedron L, V, T, of a shock absorber 1 illustrated in figure 1. In this reference, the L axis represents the longitudinal direction, the T axis represents the transverse direction, and the V axis represents the vertical direction of the object considered.

[0039] Figure 1 is a perspective view of a bumper assembly 1 comprising two shock absorbers 2 according to the invention and a cross member 4-

[0040] As illustrated in this figure, the crosspiece 4 has a main elongation direction coincident with the transverse axis T and comprises a left transverse end 6 and a right transverse end 8 arranged on either side of a central portion 10 of the crosspiece 4.

[0041] The shock absorbers 2 are arranged at each of the transverse ends 6, 8. They extend projecting from the cross member 4, more particularly from the transverse ends 6, 8 of this cross member 4 towards the motor vehicle on which they are intended to be fixed. The shock absorbers 2 here have a substantially parallelepiped shape and have a median vertical and longitudinal plane, that is to say a plane passing through a center of the vehicle on which the bumper assembly 1 is mounted and in which the axes L and V are inscribed as shown in FIG. 1. It should however be noted that alternatively, the shock absorbers 2 could take the form of a cylinder, a cone or even a pyramid.

[0042] Each shock absorber 2a, 2b is arranged between one or other of the transverse ends 6, 8 of the crossmember 4 and a fixing interface 12 for connecting the bumper assembly 1 to the motor vehicle, each fixing interface being configured to allow, for example by screwing, the fixing of the absorbers to the motor vehicle.

[0043] The shock absorbers 2a, 2b of the bumper assembly 1 are configured to absorb the energy released during an impact suffered by the vehicle on which the bumper assembly 1 is integrated, and more particularly a frontal impact. These shock absorbers 2a, 2b are thus configured, by their structure and their arrangement relative to the longitudinal dimension, to absorb a maximum of forces by deforming mainly longitudinally, in order to limit the damage caused by the impact.

[0044] Figure 2 is a perspective view of the shock absorber 2. Each shock absorber 2a, 2b comprises a plastic casing 14 and a reinforcement assembly 16 made of composite material, the plastic casing surrounding the reinforcement assembly 16 which is therefore only partially visible in Figure 2.

[0045] The plastic casing 14 has the function of structuring the shock absorbers 2a, 2b while the reinforcement assembly 16 has the function of absorbing the forces generated by a shock by deforming. As described in more detail with reference to the following figures, the reinforcement assembly 16 comprises a first composite insert 18 and an additional composite insert 20.

[0046] The plastic envelope 14 is injected around the reinforcement assembly so as to have a solid shape, with plastic material which forms in one piece a plurality of lateral faces and two longitudinal end faces connected to each other by the lateral faces. These longitudinal end faces here extend substantially perpendicular to the longitudinal direction along which it is sought to absorb the maximum forces.

[0047] In the illustrated example of a parallelepiped shape, it being understood that this shape is not limiting of the invention as mentioned previously, the plastic envelope comprises a first longitudinal end face 34 and a second longitudinal end face 36, as well as a first lateral face 22, a second lateral face 24, a third lateral face 26 and a fourth lateral face 28. Each of the lateral faces 22, 24, 26, 28 comprises a frame 30 and a network of ribs 38 which extends from one edge to the other of the frame. These ribs extend deep within the shock absorber, from the corresponding lateral face until they meet the first composite insert 18 and / or the additional composite insert 20. In this way, the network of ribs 38 of each of the faces has the role of ensuring the mechanical strength of the shock absorber by minimizing the quantity of plastic used to form the plastic casing 14.

[0048] Conversely, each longitudinal end face 34, 36 has a substantially solid surface forming a wall arranged across the longitudinal axis along which the main forces during a frontal impact propagate. This wall locally comprises perforations, in particular to ensure the attachment of the shock absorber to the cross member 4 or to the attachment interface 12.

[0049] More particularly, each longitudinal end face 34, 36 comprises at least one fixing orifice 40, possibly tapped, for fixing the shock absorber to the crosspiece 4 or to the fixing interface 12. Here, there are four fixing orifices, arranged at each corner of the corresponding longitudinal end face.

[0050] The longitudinal end faces 34, 36 may also comprise at least one opening 42 which opens onto a conduit extending along the longitudinal axis L from one longitudinal end face to the other. As will be described below, the conduit is formed by a hollow body 54, notably visible in FIGS. 4 to 6, which is delimited, in a transverse and vertical section, perpendicular to the longitudinal direction, by the junction of the first composite insert 18 and the additional composite insert 20.

[0051] In the example of Figure 2, the visible longitudinal end face has a single opening 42, in a central position, equidistant from the fixing holes, because the reinforcement assembly present within the shock absorber has a single hollow body.

[0052] As can be seen in Figure 5, there may be two openings 42, each formed in the longitudinal end face by one of the two hollow bodies formed by the specific junction of the first composite insert 18 and the additional composite insert 20.

[0053] Figures 3 to 5 illustrate several embodiments which are distinguished from each other by the fact that the composite inserts forming the reinforcement assembly have several configurations. Each of these figures includes an overall view of the shock absorber, a perspective view of the reinforcement assembly formed from the junction of the first composite insert 18 and the additional composite insert 20 and a front view of this same reinforcement assembly.

[0054] The composite inserts 18, 20 can take several shapes and configurations depending on the desired stability performance and depending on the type of vehicle on which the bumper assembly i comprising the shock absorbers 2 will be integrated, but it should be noted that in each embodiment, the two composite inserts whose junction forms the reinforcement assembly are identical.

[0055] More particularly, in each shock absorber, the first composite insert 18 is arranged against the additional composite insert 20, with substantially planar contact walls 51 which are pressed against each other to form junction zones 52. A junction plane P passes vertically through the junction zone(s) 52, the junction plane P extending vertically and longitudinally between the two composite inserts 18, 20.

[0056] Each composite insert 18, 20 is configured so that the contact wall(s) 51 are an end portion intended to be positioned on the junction plane 52, the remainder of the composite insert being arranged on the same side of these contact walls 51, opposite the other composite insert when the two composite inserts are pressed against each other.

[0057] Furthermore, each of the composite inserts 18, 20 comprises at least one curved portion 53, the radius of curvature of which is inscribed in the vertical and transverse plane, perpendicular to the longitudinal direction corresponding to the main direction of the forces to be absorbed by the shock absorber.

[0058] These curved portions 53 are formed in each composite insert to provide stability to the insert during the deformation that it must undergo compression under the axial force generated during the collision. The inventors were able to observe that the straight portions had a tendency to crumble under excessive axial force and the presence of the curved portions 53 makes it possible to locally ensure that the insert remains in place under the force.

[0059] The curved portions 53 extend from the flat contact walls 51 and thus participate in delimiting junction zones 52. It can be seen that they can be formed to orient the free ends of the inserts perpendicular to the junction plane P or that they form a separation between two adjacent junction zones 52 to participate in forming a cavity. The composite inserts are configured so that two cavities thus formed respectively on each insert are arranged facing each other and form a hollow body with a closed profile in the vertical and transverse plane, perpendicular to the longitudinal direction. The hollow body thus formed makes it possible to create an area inaccessible to the plastic material during the injection step around the composite insert, which limits the quantity injected.

[0060] In each of the embodiments illustrated in Figures 3 to 5, the first composite insert 18 is symmetrical to the additional composite insert 20 with respect to the junction plane P, which simplifies the manufacturing process operations which will be described below.

[0061] Figure 3 illustrates a first embodiment, in which the first composite insert 18 and the additional composite insert 20 are arranged against each other with a single junction zone 52 between the first composite insert and the additional composite insert, shown in dotted lines in Figure 3. The single junction zone 52 is formed by pressing against each other a flat contact wall 51 of each composite insert, which here extends over substantially the entire height, or vertical dimension, of the reinforcement assembly. The first composite insert 18 and the additional composite insert 20 each comprise a first free end 50a and a second free end 50b which extend each of the ends of the contact wall 51, each of these ends extending perpendicular to the contact wall 51 and therefore perpendicular to the junction plane P when the composite inserts form the reinforcement assembly.

[0062] In this first embodiment, the curved portions 53 of each composite insert are arranged between the flat contact wall 51 and each free end 50a, 50b.

[0063] Figure 4 illustrates a second embodiment, which differs from the first embodiment in that the composite inserts 18, 20 are arranged against each other with several junction zones including a first junction zone 52a between the first composite insert and the additional composite insert and a second junction zone 52b between the first composite insert and the additional composite insert. The first junction zone 52a and the second junction zone 52b are discontinuous and participate in delimiting, with curved portions 53 extending these junction zones, a hollow body 54. The hollow body 54 occupies a substantially large space, making it possible to reduce the quantity of plastic to be injected to cover the reinforcement assembly 16 comprising the composite inserts 18, 20 once joined.

[0064] Here again, the first composite insert 18 and the additional composite insert 20 each comprise a first free end 50a and a second free end 50b which extend the end of the contact walls 51 opposite the hollow body 54, each of these ends extending perpendicular to the contact walls 51 and therefore perpendicular to the junction plane P when the composite inserts form the reinforcement assembly.

[0065] Figure 5 illustrates a third embodiment, which differs on the one hand by the number of hollow bodies 54 generated in the reinforcement assembly and on the other hand by the orientation of the free ends 50a, 50b, which are here parallel to the junction plane and not perpendicular to this junction plane as previously mentioned.

[0066] More particularly, the composite inserts 18, 20 are arranged against each other to form three discontinuous joining zones, including a first joining zone 52a, a second joining zone 52b and a third joining zone 52c, each of these joining zones being between the first composite insert 18 and the additional composite insert 20. The third joining zone 52c is here arranged between the first zone 52a and the second joining zone 52b. The first joining zone 52a is merged with the first free end 50a and the second joining zone 52b is merged with the second free end 50b.

[0067] The first junction zone 52a and the third junction zone 52c, respectively extended towards each other by curved portions 53, participate in delimiting a first hollow body 54a, while the third junction zone 52c and the second junction zone 52b, respectively extended towards each other by curved portions 53, participate in forming a second hollow body 54b.

[0068] Figure 6 describes a method of manufacturing the shock absorber 2, here with reference to the second embodiment illustrated in Figures 2 and 4.

[0069] Firstly, the composite inserts 18, 20 are heated, which are in a flat shape. Then, the composite inserts 18, 20 are arranged in an injection tool 56, shown here schematically with a two-part mold. Within the injection tool, the flat contact wall 51 of each of the composite inserts 18, 20 is folded to locally give these inserts an appropriate curved shape, that is to say to generate the desired curved portions 53 in order to give this insert a specific profile. In the example illustrated, each insert is folded at its ends to make the free ends 50a, 50b perpendicular to the flat contact wall 51 and each insert is also deformed by a pusher of appropriate shape to form a curved portion in the shape of a bowl in the center of the flat contact wall 51.The curved portions 53 are formed while leaving the undeformed plane contact wall portions a sufficient extent to allow the two composite inserts 18, 20 to come into contact with each other. The composite inserts are then pressed against each other at these plane contact walls to form the junction zones by closing the injection tool. It is then appropriate to inject the plastic material around the reinforcement assembly thus formed to generate the shock absorber.

[0070] It follows from the foregoing description that the invention achieves the aims it has set itself by proposing a shock absorber made of a composite material surrounded by plastic, simple to manufacture and inexpensive, and which makes it possible to ensure stability of the absorber during an impact without it being necessary to provide a significant quantity of plastic around the composite insert, the plastic being able to have low resistance to very low temperatures. The invention cannot, however, be limited to the means and configurations described and illustrated here, and it also extends to any equivalent means or configurations and to any technically effective combination of such means. In particular, the dimensions and shapes of the composite inserts can be modified without detriment to the invention, insofar as they fulfill the functionalities described in this document.

Claims

CLAIMS 1. Shock absorber (2) for a motor vehicle, comprising at least one plastic casing (14) and a first composite insert (18), characterized in that the shock absorber (2) comprises at least one additional composite insert (20) which is arranged against the first composite insert (18) with at least one junction zone (52) between the first composite insert (18) and the additional composite insert (20) so as to form a reinforcement assembly (16), the first composite insert (18) and the additional composite insert (20) being arranged on either side of a junction plane (P) in which the at least one junction zone (52) extends, the plastic casing (14) surrounding said reinforcement assembly (16).

2. Shock absorber (2) according to claim 1, wherein the first composite insert (18) and the additional composite insert (20) each comprise at least one curved portion (53).

3. Shock absorber (2) according to claim 2, in which different discontinuous junction zones (52) are formed in the junction plane (P) between the first composite insert (18) and the additional composite insert (20), the curved portions (53) participating in forming at least one hollow body (54) arranged between the composite insert (18) and the additional composite insert (20), the junction plane (P) passing through each hollow body (54).

4. Shock absorber (2) according to one of the preceding claims, in which the first composite insert (18) and the additional composite insert (20) are symmetrical to each other with respect to the junction plane (P).

5. Shock absorber (2) according to any one of the preceding claims, in which the plastic casing (14) has two longitudinal end faces (34, 36) and side faces (20, 22, 24, 26), the longitudinal end faces and the side faces being composed of plastic material.

6. Shock absorber (2) according to claim 5, in combination with claim 3, wherein the two longitudinal end faces (34, 36) comprise at least one opening (37) arranged opposite a hollow body (54) formed by the junction of the first composite insert (18) and the additional composite insert (20).

7. Shock absorber (2) according to any one of claims 1 to 6, in which the first composite insert (18) and the additional composite insert (20) each have a profile formed of curved portions and flat portions forming the functional zones, said profile extending between a first free end (50a) and a second free end (50b), the free ends (50a, 50b) being perpendicular to the junction plane (P).

8. Shock absorber (2) according to claim 7 in combination with claim 3, in which the first composite insert (18) and the additional composite insert (20) are arranged against each other forming two junction zones between the first composite insert and the additional composite insert which are discontinuous and separated by a single hollow body (54), each of the junction zones extending in the vicinity of one of the free ends (50a, 50b).

9. Shock absorber (2) according to any one of claims 1 to 6, in combination with claim 3, in which the first composite insert (18) and the additional composite insert (20) comprise free ends (50a, 50b) which extend substantially parallel to the junction plane (P) and which form one of the junction zones (52), the reinforcement assembly comprising at least one hollow body (54) generating a discontinuity between two junction zones (52).

10. A method of manufacturing a shock absorber (1) according to any one of claims 1 to 9, in combination with claim 2, during which: - The first composite insert (18) and the additional composite insert (20) initially presented in flat form are preheated before placing them in an injection tool (56); - The first composite insert (18) and the additional composite insert (20) are preformed in the injection tool (56) by creating curved portions (53), while maintaining flat contact walls. intended to be pressed against each other to form the junction zones (52); - The first composite insert (18) and the additional composite insert (20) are assembled by pressing their flat contact walls forming at least one flat junction zone (52) against each other when the injection tool (56) is closed; - Plastic material is injected around the reinforcement assembly formed by the junction of the first composite insert (18) and the additional composite insert (20) once the injection tool (56) is closed.

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