Rods for joining automotive components and related manufacturing methods

Abstract

The invention relates to a connecting rod comprising at each of its two ends a connecting part intended to cooperate with an external member, one of said connecting parts comprising a yoke (1) and the other of said connecting parts comprising an eyelet (3), said yoke (1) being joined to said eyelet (3) by means of a continuous reinforcing strip (5) forming a loop, said yoke (1), said eyelet (3) and said strip (5) being at least partially overmolded by a thermoplastic material (15).

Description

Technical Field

[0001] Field of the Invention The present invention relates to the field of mechanics, and more specifically, to the field of components involved in the structure of automobiles.

Background Art

[0002] Technical Field of the Invention In an automobile, certain members must be firmly joined to each other and be relatively movable along a predetermined path.

[0003] For this purpose, connecting rods are provided. The ends of these connecting rods are rotatably attached to the respective members that are relatively movable along a predetermined path.

[0004] An example of such a connecting rod is the torque take-up connecting rod of an automobile engine, which is interposed between this engine and the vehicle chassis.

[0005] Another example of such a connecting rod is the connecting rod between an automobile cradle and a wheel support.

[0006] Prior Art For certain applications, it is desirable to be able to use a connecting rod having a connecting eyelet at one end and a connecting yoke at the other end.

[0007] This is, for example, the case of the connecting rod of a cradle / wheel support, where the eyelet of this connecting rod cooperates with the cradle and the yoke cooperates with the wheel support.

[0008] Conventionally, these prior art connecting rods have been formed from metal or metal alloys, such as extruded aluminum or cast steel.

[0009] The main drawback associated with these materials is their weight. Therefore, these materials do not offer a satisfactory solution, especially when automotive manufacturers impose strict weight constraints on components of the vehicle structure.

[0010] Furthermore, prior art includes connecting rods made from thermoplastic materials, equipped with eyelets at both ends. While these are lighter, their mechanical strength is inferior. [Overview of the project] [Problems that the invention aims to solve]

[0011] Therefore, the object of the present invention is to provide connecting eyelet and yoke-type connecting rods for automotive structures that are lighter than those of the prior art and have at least equivalent mechanical strength. [Means for solving the problem]

[0012] The above-mentioned problems of the present invention are solved by a connecting rod having a connecting portion at each of its two ends, which is intended to cooperate with an external member, one of which has a yoke and the other has an eyelet, the yoke being connected to the eyelet by a continuous reinforcing strip forming a loop, and the eyelet, the yoke and the strip being overmolded at least partially with a thermoplastic material.

[0013] These features result in a connecting rod that possesses not only strength due to the presence of continuous reinforcing strips, but also lightness due to the use of thermoplastic materials instead of metals or metal alloys in prior art.

[0014] According to other optional features of the connecting rod according to the present invention, the following matters may be adopted individually or in combination.

[0015] The aforementioned yoke is formed from metal or a metal alloy by pressing, casting, extrusion, and / or machining, and / or by welding multiple metal elements together. The use of metal or a metal alloy allows for the assurance of good long-term stability of this end of the connecting rod, which is intended to work with automotive components, such as wheel support members, by bolting.

[0016] The yoke described above has an omega cross-section in the zone that works in cooperation with the reinforcing strip described above. Such a cross-section allows for the assurance of an optimal stress distribution in the yoke and other parts of the connecting rod, and more specifically, this omega cross-section allows for press workability with a small bending radius while obtaining a high second moment of cross-section.

[0017] The aforementioned yoke has a weak zone adapted to collapse before other parts of the connecting rod when a force exceeding a predetermined threshold is applied. This allows the connecting rod to deform at this part of the yoke rather than elsewhere in the event of a collision between the vehicle and an external obstacle, thereby enabling control over the mode of embrittlement of the connecting rod in extreme situations.

[0018] The eyelet described above comprises an elastic element with a substantially tubular metal element inserted in the center. This elastic element may, for example, be annular (though not mandatory), and allows for filtering of vibrations transmitted by the connecting rod, while the metal insert allows for the elastic element to be bolted to the vehicle structure without the risk of wear of the element.

[0019] The reinforcing strips described above have long, continuous fibers embedded in the resin, such as glass fibers or carbon fibers, or plant fibers, such as flax fibers or nettle fibers. For example, but not limited to, such reinforcing strips made of polyamide resin have the advantage of being very strong in tensile force and, at the same time, flexible enough to be easily implemented between the yoke and the eyelet during the process of manufacturing the connecting rod.

[0020] The thermoplastic overmolding described above is manufactured from the same or chemically miscible resin as the resin coating the fibers of the reinforcing strip described above. Such overmolding can be easily and inexpensively performed using conventional injection molding tools, and it also protects the reinforcing strip from gravel and other particle protrusions during vehicle movement. Because it is made from the same or chemically miscible resin as the resin coating the reinforcing strip, excellent bonding strength is obtained between this overmolding and the reinforcing strip.

[0021] The overmolding described above has cavities and ribs. These ribs and cavities are positioned along the main force paths, saving material to be overmolded and thus reducing the weight and manufacturing cost of the connecting rod. In addition, the ribs positioned between the reinforcing strip and the periphery of the connecting rod allow the reinforcing strip to be positioned away from external mechanical impacts such as impacts from gravel or other particles when the vehicle is moving.

[0022] The present invention also relates to a method for manufacturing the connecting rod described above, wherein the reinforcing strip described above is passed inside the yoke described above and around the eyelet described above, and these three thus connected portions are placed in an injection mold into which an overmolding material is injected.

[0023] At that time, the overmolding material covers at least a part of the yoke, the eyelet and the reinforcing strip, thereby making it possible to fix these parts together.

[0024] When the eyelet has an annular elastic element, while the overmolding material is injected into the mold, pressure is applied by the overmolding material, making it possible to compress this annular elastic element towards its center. Thereby, the life of this elastic element can be extended.

[0025] Other features and advantages of the present invention will become apparent by reading the following description with reference to the accompanying drawings.

Brief Description of the Drawings

[0026] [Figure 1] It is a figure showing a perspective view of the yoke, the eyelet and the reinforcing strip of the connecting rod according to the present invention before its assembly and before its overmolding. [Figure 2] It is a figure showing a perspective view of this yoke, this eyelet and this strip after its assembly and before its overmolding. [Figure 3] It is a figure showing a perspective view of the connecting rod according to the present invention after overmolding of the yoke, the eyelet and the reinforcing strip. [Figure 4] It is a figure showing a plan view of this connecting rod. [Figure 5] It is a figure showing a cross-sectional view of this connecting rod along line A-A of FIG. [Figure 6] It is a figure showing a cross-sectional view of this connecting rod along line B-B of FIG. [Figure 7] It is a figure showing a figure similar to that of FIG. 2 with a modified example of the yoke. [Figure 8] It is a figure showing a figure similar to that of FIG. 2 with yet another modified example of the yoke. [Figure 9]Figures 1-6 show the connecting rods, which have a planned vulnerable zone. [Figure 10] This diagram shows the connecting rod after the yoke has been damaged. [Figure 11] This figure shows a perspective view similar to those in Figures 2, 7, and 8, with yet another modified yoke. [Modes for carrying out the invention]

[0027] For clarity, identical or similar elements are indicated by the same or similar reference numerals throughout these figures.

[0028] Herein, Figure 1 is referenced, which shows three parts that form a portion of the connecting rod according to the present invention.

[0029] These three parts comprise a yoke 1, an eyelet 3, and a reinforcing strip 5.

[0030] Yoke 1 can be manufactured from steel or other metal alloys that meet the specifications imposed by the manufacturer by pressing, casting, extrusion, and assembly of mechanically welded parts.

[0031] The yoke 1 is equipped with orifices 7a and 7b at each of its lateral branches 2a and 2b. The central portion 9 of this yoke, which connects the two lateral branches 2a and 2b together, has an omega cross-section, as can be seen, for example, in Figure 5.

[0032] The eyelet 3 preferably, but not limited to, comprises an annular element 11 formed from an elastic material such as natural rubber or synthetic rubber, which is preferably overmolded by bonding onto a substantially tubular element 13 formed from metal.

[0033] The reinforcing strip 5, which has a width that may, for example, but not limited to, be on the order of 20 mm and a thickness on the order of 1 mm, is formed from a resin such as a polyamide resin that captures long, continuous reinforcing fibers, such as glass fibers or carbon fibers, or plant fibers, such as flax fibers or nettle fibers, and these fibers are arranged substantially along the direction of the length of the strip 5.

[0034] While polyamide resins are given as an example, it goes without saying that other resins used in the field of composite materials could also be suitable.

[0035] This reinforcing strip 5 forms a continuous loop, i.e., it has no interruptions.

[0036] As can be seen in Figure 2, the reinforcing strip 5 is intended to pass around the annular rubber element 11 of the eyelet 3, inside the yoke 1, and around the central portion 9 of the yoke, that is, in contact with the convex portion of the omega cross-section of the central portion 9.

[0037] This particular cooperation between the reinforcing strip 5, the yoke 1, and the eyelet 3 can also be seen in Figure 5.

[0038] Figures 3, 4, 5, and 6 show the connecting rod according to the present invention after overmolding with a thermoplastic material identical to or chemically miscible with the resin of the reinforcing strip 5, such as polyamide resin.

[0039] As can be seen in these figures, this thermoplastic material 15 covers the central portion 9 of the yoke 1, the eyelets 3, and the reinforcing strips 5.

[0040] As can be seen particularly in Figures 3 and 5, this overmolded thermoplastic material features ribs 17 and cavities 19 that are appropriately positioned with respect to the stress paths resulting from the design calculations.

[0041] Some of these ribs maintain a space between the reinforcing strip 5 and the periphery of the connecting rod, thereby protecting the reinforcing strip from external attacks.

[0042] In particular, note that the circular ribs 21 surround the annular rubber element 11, and the thermoplastic material 15 completely covers the central portion 9 of the yoke 1, which has an omega cross-section.

[0043] Preferably, the polyamide resin that enables the acquisition of the overmolding 15 is itself filled with reinforcing fibers, such as glass fibers or carbon fibers, or plant fibers, such as flax fibers or nettle fibers, which are preferably arranged along the longitudinal direction of the connecting rod.

[0044] To obtain the connecting rod according to the present invention, a yoke 1, eyelet 3, and reinforcing strip 5 are arranged in an injection mold, with two half-molds of this injection mold having recesses corresponding to the female mold of the overmolded plastic material 15, as can be seen in Figures 3 and 5.

[0045] After placing the three parts 1, 3, and 5 within the mold, polyamide resin is injected into the mold, causing the resin to circulate within all the recessed zones defining the ribs 17 and 21.

[0046] The injection pressure makes it possible to apply a radial compressive force, particularly to the annular rubber element 11, against the tubular metal element 13.

[0047] The element 11, which has a special undercoat pre-applied to its periphery, is completely bonded to the circular rib 21.

[0048] The overmolding thus obtained makes it possible to protect the reinforcing strip 5 from protrusions of gravel or other particles that may occur when the vehicle is in motion.

[0049] The overmolded strips in this manner enable the connecting rod according to the present invention to achieve excellent resistance to tensile and compressive forces.

[0050] The radial compressive force generated in the elastic annular element 11 during overmolding allows the annular element to be kept under prestress, thus preventing premature wear of the rubber constituting the annular element.

[0051] The omega profile of the central portion 9 of the yoke 1 allows the yoke to be manufactured by press forming without the risk of stress concentration, particularly at the connecting portion of this central portion with the branches 2a and 2b of the yoke.

[0052] Preferably, a specific, predetermined vulnerable zone can be provided in the yoke 1, so that when a large impact occurs, the connecting rod becomes more brittle in that zone than elsewhere, which allows for control over the behavior of the connecting rod in the accident situation. Such a vulnerable zone 23 is shown as an example in Figures 9 and 10, before and after the failure of the yoke.

[0053] The two orifices 7a and 7b formed on the branches 2a and 2b of the yoke 1 are typically intended to work in cooperation with the wheel support eyelets of an automobile.

[0054] The tubular element 13 of the eyelet 3 is typically intended to work with a stud, or more commonly, with a clevis fixed to the axle cradle of an automobile.

[0055] Figures 7 and 8, which are similar to Figure 2, show two variations of the yoke. In Figure 7, yoke 1 is formed from extruded aluminum, while in Figure 8, yoke 1 is ribbed and formed from cast steel.

[0056] Figure 11 shows a modified example in which the yoke 1 is formed by a mechanically welded assembly of multiple metal parts.

[0057] As can be understood in light of the above, the connecting rod and related manufacturing method according to the present invention makes it possible to obtain a strong connecting rod manufactured from an extremely lightweight material.

[0058] Such connecting rods can be used not only for the joints of automobile wheels, but also, subject to the necessary geometric adaptations, as torque take-up arms interposed between, for example, the engine and chassis of an automobile.

[0059] Naturally, the present invention is described above as an example. Those skilled in the art will understand that various modified embodiments of the present invention can be manufactured without departing from the scope of the present invention.

Claims

1. A connecting rod having a connecting portion at each of its two ends, intended to work with an external member, wherein one of the connecting portions comprises a yoke (1), and the other of the connecting portion comprises an eyelet (3), the yoke (1) is connected to the eyelet (3) by a continuous reinforcing strip (5) forming a loop, and the yoke (1), the eyelet (3), and the strip (5) are at least partially overmolded with a thermoplastic material (15). The yoke (1) is a connecting rod having an Ω-shaped cross-section in a zone (9) that cooperates with the reinforcing strip (5).

2. The connecting rod according to claim 1, wherein the yoke (1) is formed from metal or a metal alloy by pressing, casting, extrusion, and / or machining, and / or welding together a plurality of metal elements.

3. The connecting rod according to claim 1 or 2, wherein the yoke (1) has a vulnerable zone adapted to collapse before the rest of the connecting rod when a force exceeding a predetermined threshold is applied.

4. The connecting rod according to any one of claims 1 to 3, wherein the eyelet (3) comprises an elastic element (11) in which a substantially tubular metal element (13) is inserted in the center.

5. The connecting rod according to any one of claims 1 to 4, wherein the reinforcing strip (5) has long, continuous fibers embedded in the resin, such as glass fibers or carbon fibers, or has plant fibers, such as flax fibers or nettle fibers.

6. The connecting rod according to any one of claims 1 to 5, wherein the thermoplastic material (15) is manufactured from the same resin as or a chemically miscible resin as the resin coating the fibers of the reinforcing strip.

7. The connecting rod according to any one of claims 1 to 6, wherein the overmolded thermoplastic material (15) has a cavity (19) and a rib (17).

8. A method for manufacturing a connecting rod according to any one of claims 1 to 7, comprising passing the reinforcing strip (5) inside the yoke (1) and around the eyelet (3), arranging the three thus connected portions in an injection mold, and injecting an overmolding material (15) into the injection mold.

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