WO2022096609A1

WO2022096609A1 - Device for a motor vehicle transmission chain

Info

Publication number: WO2022096609A1
Application number: PCT/EP2021/080694
Authority: WO
Inventors: Cristiano Baudino; Luca ZANCO; Roberto VERGARI
Original assignee: Valeo Embrayages
Priority date: 2020-11-06
Filing date: 2021-11-04
Publication date: 2022-05-12
Also published as: EP4240988A1; CN220523180U; FR3116093A1; FR3116093B1

Abstract

The invention relates to a device (10) for a motor vehicle transmission chain, comprising: - a rotating element (3) intended to be mounted to rotate about an axis (X) of rotation, the rotating element (3) comprising a radial portion (7), and a cylindrical skirt (8) of radial dimension (Ep), extending from the radial portion (7), - an annular cover (9), arranged with the rotating element (3) in order to enclose resilient members (5), wherein the cylindrical skirt (8) of the cylindrical skirt (8) and the cover (9) each comprise positioning means (80, 90) mutually interacting so as to position the cover (9) on the rotating element (3), the positioning means (80, 90) of the cylindrical skirt (8) and the cover (9) being fastened together by welding.

Description

DESCRIPTION

TITLE OF THE INVENTION: DEVICE FOR AN AUTOMOTIVE VEHICLE TRANSMISSION CHAIN

[1] The present invention relates to the field of vehicle transmission chains, more precisely a device fitted to a transmission chain for a vehicle. The invention relates in particular to a dual mass flywheel.

[2] It is known to equip vehicle transmissions with a double damped flywheel, comprising a primary flywheel and a coaxial secondary flywheel, movable in rotation with respect to each other, in particular to filter the vibrations generated by the acydisms upstream of the gearbox. The primary and secondary flywheels are coupled in rotation by elastic members making it possible to transmit a torque and to dampen acydisms between the primary and secondary flywheels.

[3] In known manner, the primary flywheel comprises a rotating element intended to be fixed to the crankshaft, for example of a combustion engine, and a cover intended to contain the elastic members. Document DE102018128216 A1 discloses such a primary flywheel of a dual mass flywheel, in which the cover and the rotating element are fixed integrally end to end by laser welding for optimum welding. But this solution has drawbacks.

[4] The laser welding process enables end-to-end assembly of the outer peripheries of the cover and the rotating element, but imposes a very small clearance between parts, with acceptable geometric contours, due to the lack of filler material and the thinness of the beam of the laser source. The manufacture of these parts, by cutting and stamping, nevertheless generates shapes that are not suitable for laser welding.

[5] Additional machining operations are required, so that the shapes are compatible and the clearance between parts becomes acceptable again for laser welding. Furthermore, the end-to-end assembly of the parts is cumbersome within the device, and forces the use of additional parts to equip the primary flywheel, such as for example an inertia ring added by welding against a face of the lid. The assembly steps and the cost of making such a device forming the primary flywheel are therefore high.

[6] The purpose of the invention is in particular to provide a simple, effective and economical solution to this problem.

[7] For this purpose the invention proposes, according to a first aspect, a device for a motor vehicle transmission chain, comprising:

- a rotary element intended to be mounted in rotation around an axis of rotation, the rotary element comprising a radial extension portion and a cylindrical skirt which extends from the radial extension portion,

- an annular cover, arranged with the rotary element to enclose elastic members, in which the cylindrical skirt and the cover each comprise positioning means cooperating together so as to position the cover on the rotary element, said means of positioning of the cylindrical skirt and the cover being fixed together by welding.

[8] Thanks to these characteristics, this device makes it possible to simplify the mounting and assembly of the cover on the rotating element. By forming positioning means on each of the parts, the cover is positioned axially on the cylindrical skirt, in a simple and quick way, even manually, without the need for preparatory work or additional operation. Their joint cooperation, in particular ensures the positioning means an angular indexing of the cover on the cylindrical skirt, for example by complementarity of form. Such positioning means offer greater geometric tolerance in the manufacture of the parts, while avoiding abutment problems between the cover and the cylindrical skirt, such as resulting from assembly defects by laser welding.

[9] The assembly of the positioning means is also carried out in a single welding operation, in a simple manner, without the need for post-operative finishing, such as for example welding with filler material or arc welding. This fixing of the positioning means between them makes it possible to solidly link the cover to the cylindrical skirt.

Costs are significantly reduced. The design and assembly of such parts are simplified and optimized. A single part can combine several functions, for example, the end of the cylindrical skirt of the rotating element can receive a starting ring, by interference or by welding, thus reducing the number of parts present in the within the device. It is also possible to design the cover in a simplified manner, in its most essential form, in order to reduce its size, its weight or even to simplify its assembly within such a device.

[10] Such a device in accordance with the first aspect of the invention may have one or other of the characteristics described below combined with each other or taken independently of each other:

[11] - Advantageously the cylindrical skirt can surround the lid. The cover can therefore be contained inside the cylindrical skirt of the rotating element. The advantage here is to limit the size of the two parts, by arranging the cover radially inside the cylindrical skirt of the rotating element.

The cover positioning means being formed from the outer diameter D3 of the cover. The advantage here is to limit the size of the two parts, by arranging the cover radially below the cylindrical skirt of the rotating element. The cover positioning means can be arranged substantially along an implantation circle C2 which can be equal to or greater than the outer diameter of the cover, and in particular between the outer diameter of the cover and the inner diameter of the cylindrical skirt;

[12] - In particular, the means for positioning the cylindrical skirt can be formed from the inside diameter D1 of the cylindrical skirt, in order to limit their size. The means for positioning the cylindrical skirt can be arranged substantially along a implantation circle C1 which can be between the inner and outer diameters of the cylindrical skirt. The shape of the cover can be simplified, for example entirely contained in a plane P perpendicular to the axis X, that is to say exempt from deformed, offset or axially depressed portions;

[13] - In particular, the means for positioning the cylindrical skirt and the cover can be arranged substantially along one and the same implantation circle, which can be between the internal diameter of the cylindrical skirt and the diameter exterior of the lid. Such positioning means are therefore located at the same radial distance from the axis of rotation. The result is uniform radial support for the assembly of said parts, via the positioning means cooperating jointly only at certain locations of said parts.

These provide a large number of functions: the positioning means of said parts cooperate together so as to achieve both the axial retention, the centering and the angular indexing of the cover on the cylindrical skirt;

[14] - Advantageously the lid positioning means may be of complementary shape to that of the positioning means of the cylindrical skirt;

[15] - The means for positioning the cylindrical skirt and the cover can be fixed together by a weld bead. Thus the weld bead can be produced at least in part at said means for positioning the cylindrical skirt and the cover. The weld bead may extend at least partially around the X axis of rotation, in particular over at least 240 degrees. The weld bead can extend continuously around the X axis, over 360 degrees, thus guaranteeing a fixed assembly of the positioning means in the axial and angular directions. From then on, the entire cover is firmly attached to the cylindrical skirt;

[16] - The weld bead can be made by welding with addition of material;

[17] - The weld bead can preferably be made by arc welding, in particular by cold welding. The advantage of such arc welding is to reduce heat generation (cold welding principle). This reduces the deformations and increases the tolerance at the level of the docking clearances J, in particular at the level of the positioning means of the two parts. It is therefore no longer necessary to carry out preparatory work for the positioning of the cylindrical skirt and the lid, nor post-operative finishing operations on these parts;

[18] - The rotating element and the means for positioning the cylindrical skirt can form a single piece, made in one piece The means for positioning the cylindrical skirt can be in one piece with the cylindrical skirt;

[19] - The cover and the means for positioning the cover can form a single piece, made in one piece The means for positioning the cylindrical skirt can be in one piece with the rest of the cover;

[20] - The cylindrical skirt may comprise a particular profile intended to cooperate with the positioning means of the cover; [21] - The lid may comprise a particular profile intended to cooperate with the positioning means of the cylindrical skirt;

[22] - The positioning means can be produced by pressing the cylindrical skirt and the cover respectively. Preferably, the positioning means can be produced by stamping or by machining the rotary element and the cover respectively. The advantage is to make these means partially, and not over the entire part. Manufacturing is simplified, in particular by limiting machining or stamping to only places which would be either intended, or not intended, to form the positioning means on each part;

[23] - Alternatively said means for positioning the cylindrical skirt and the cover can be formed by cutting, by stamping, or by any other method known to those skilled in the art;

[24] - The cylindrical skirt of the rotary element and the cover can each comprise at least three positioning means preferably distributed angularly around the axis, in particular according to a regular distribution. The support of the lid is thus evenly distributed over the surface of the skirt. The lack of parallelism of the parts is limited. In other words, the positioning of said parts is more precise and stable. These assemblies are less expensive;

[25] - The positioning means of the cylindrical skirt can be of identical shape;

[26] - The lid positioning means may be of identical shape;

[27] - The number of positioning means for each part can be even, or alternately, odd.

[28] - Preferably, the cylindrical skirt of the rotary element and the cover may comprise an identical number of positioning means. Therefore, these positioning means may be arranged radially and/or axially opposite each other, so as to facilitate indexing during assembly;

[29] - Advantageously, the cylindrical skirt of the rotary element and the cover can each comprise a limited number of positioning means, for example less than five, preferably equal to three positioning means per part. Note that the fewer positioning means there are (limited number), the easier it will be to adjust the production parameters and the tooling to obtain a good planarity of the contact plane between the parts. The positioning means are advantageously limited according to, for example, the dimension and the shape given to the positioning means;

[30] - In a first variant, the cover positioning means may be support lugs positioning the radial part of the cover relative to the cylindrical skirt of the rotating element;

[31] - In a second variant, the cylindrical skirt can form at least one bearing seat, the cover forming at least one protuberance, the cylindrical skirt and the cover cooperating by positioning the protrusion on the respective bearing seat . The support seat and the protrusion form the means for positioning the cylindrical skirt and the cover;

[32] - In particular, the cylindrical skirt forms at least two support seats, the cover forming at least two protrusions, the cylindrical skirt and the cover cooperating by positioning said protrusions on said respective support seats. In other words, the means for positioning the cylindrical skirt and the cover can be protrusions of the cover, coming to be positioned on bearing seats formed in the cylindrical skirt of the rotating element. The advantage of these protrusions is to ensure a larger surface for centering the cover with the cylindrical skirt, in particular by reducing the radial distance between parts to a strict minimum. The size and the need for material of such parts are therefore limited via only the protrusions and the support seats cooperating jointly;

[33] - The support seat can be produced by machining the cylindrical skirt, i.e. by machining the specific place forming the support seat. Alternatively, the support seat can be made by stamping the cylindrical skirt;

- The protrusion can be made by machining the rest of the cover, i.e. by machining the resulting space between the adjacent protrusions of the cover. Alternatively, the protrusion can be made by stamping the lid:

[34] - The protrusions of the cover can be of complementary shape to that of the support seats of the cylindrical skirt. This simplifies the centering and indexing of the cover, manually without the need for special tools before welding; [35] - The protrusion may include several support faces intended to be received on a support seat;

[36] - The growths are solid portions, male in shape, and may be of identical shape. A protrusion can thus extend discontinuously in the circumferential direction around the X axis;

[37] - In particular, each outgrowth can be opened radially outwards;

[38] - The growths of the cover can be deformed convex;

[39] - The protrusions can for example be deformed rounded and extend radially outwards, from the outer diameter of the lid, that is to say in the direction of the cylindrical skirt;

[40] - Alternatively, the protuberances may be polygonal in shape, for example, triangular, rectangular, or trapezoidal. For example, the protuberances can each be, in a plane orthogonal to the X axis, a tooth-shaped projection;

[41] - By "support seat", we mean in particular an open-type recess made in the cylindrical skirt in order to accommodate at least one of the lid positioning means. The depth of the recess is such that it is distinguished from a simple notch or notch, to mount and position the cover positioning means;

[42] - Preferably, the cylindrical skirt may have a maximum thickness Ep measured along a reference axis, and the support seat may have a depth measured along another axis parallel to the axis reference. In particular, said reference axis is in the radial direction;

[43] - The depth of the bearing seat can be the maximum dimension of the bearing seat in the radial direction;

[44] - The depth of the bearing seat can be between 15% and 70% of the maximum thickness Ep of the cylindrical skirt;

[45] - The depth of the bearing seat can be between 25% and 65% of the maximum thickness Ep of the cylindrical skirt.

[46] - For example, it can be equal to or greater than 35% of the maximum thickness Ep of the cylindrical skirt;

[47] - In particular, it can be between 30% and 60% of the maximum thickness Ep of the cylindrical skirt.

[48] For all these ranges of values, a depth (for example a radial type dimension) of the support seat is therefore established, sufficient and limited in relation to the rest of the cylindrical skirt, to accommodate the means for positioning the cover. Beyond such a range of values, the cylindrical skirt the rotating element could be damaged, during assembly with the cover or even in operation on a vehicle, or else of insufficient size to support the protrusion. These ranges of values thus offer the additional possibility of reducing the radial size, without causing problems with the centering support, or irreversibly damaging the cylindrical skirt housing the cover;

[49] - Preferably, the support seats can be hollow portions, of female shape, and can be of identical shape. A support seat may extend discontinuously in the circumferential direction around the X axis;

[50] - In particular, each support seat can be opened radially downwards;

[51] - A support seat can be a housing, an opening, a cavity or a recess in the material;

[52] - Preferably, the bearing seats of the cylindrical skirt can be concave in shape. The bearing seats can be rounded in shape and extend from the inside diameter of the cylindrical skirt, i.e. towards the lid.

[53] - Alternatively, the support seats can be polygonal in shape, for example, of the triangular, rectangular, or trapezoidal type;

[54] - Advantageously the support seat may have a stepped shape, hollowed out from an end edge of the cylindrical skirt along an axis which is orthogonal to the X axis of rotation. Therefore, a distal portion of the support seat is hollowed out to a greater depth than a proximal portion of the same support seat. In such a situation, the end of the protrusion is supported on the distal part of the support seat. In other words, the distal part of the support seat defines the bottom of the support seat. Preferably, the remaining space of the distal part can partly receive a weld bead. [55] - In particular, the spacing between the distal part of the bearing seat and the end edge of the cylindrical skirt is such that it defines a radial edge of the bearing seat. Therefore, the bearing seat may comprise a radial edge extending from the end edge of the cylindrical skirt to the bottom of the bearing seat;

[56] - In other words, the support seat can include:

- a distal part with respect to the end edge of the cylindrical skirt, said bottom, on which the end of the protuberance rests, the remaining space of the bottom of the support seat partly receiving a weld bead ,

- a radial edge on which a bearing face of the protrusion bears, the radial edge of the bearing seat extending from the end edge of the cylindrical skirt to the bottom of the bearing seat.

[57] This form of support seat has the advantage of being simple to produce, in particular by stamping or material removal processes, of the machining type. The radial edge of the bearing seat makes it possible to position and hold the protrusions of the cover on the cylindrical skirt, while the distal part of the bearing seat makes it possible to center the protrusions of the cover relative to the cylindrical skirt.

[58] The space delimited by the distal part (bottom of the support seat) also has the advantage of partly receiving the weld fixing the positioning means, which optimizes the size of the parts once they are assembled;

[59] - The support seat may have a substantially rectangular shape in cross-section, or in the shape of a hollow half-cylinder, half-sphere or groove. By way of example, a support seat can be, in a plane orthogonal to the X axis, a cavity or recess of circular or rounded shape;

[60] - In particular, the support seat may have a semicircular shape in cross section;

[61] - In particular, one of the lateral bearing faces of the protrusion can be received on the radial edge of the bearing seat, while another lateral bearing face can receive the weld bead;

[62] - In particular, the radial edge of the bearing seat and the weld bead may be arranged axially on either side of the cover, so as to solidly link the outgrowth of the cover to the bearing seat;

[63] - In other words, by defining a plane P crossing the cover and the axis X, the radial edge of the support seat and the weld bead can be arranged axially on either side of the plane P Thanks to its characteristics, the lid is positioned and fixed axially to the cylindrical skirt, on one side, thanks to the weld bead connecting the lid to the distal part of the support seat, on the other side, thanks to the edge radial of the bearing seat in abutment on the cover. This arrangement therefore has the advantage of holding the cover fixedly, to limit the lack of parallelism between the parts.

[64] - Specifically, the weld bead can be partly arranged together on a first bearing face of the protrusion and on the distal part of the support seat, to solidly link the protrusion and the seat of support;

[65] - Advantageously, one of the bearing surfaces of the protuberance can form a groove or a rib with the lid, said groove or rib cooperating with the end edge of the cylindrical skirt and/or with the support seat;

[66] - In particular, said groove or rib can cooperate with a radial edge of the bearing seat.

[67] The advantage of these forms is to simplify their cooperation, for example:

- either by housing the outgrowth rib on the end edge and on part of the support seat, called the radial edge,

- either by housing part of the support seat, known as the radial edge, in the groove of the protrusion;

[68] - In particular, said groove or rib may be of complementary shape to that of said radial edge, their bearing also simplifying the centering of the lid on the cylindrical skirt;

[69] - The cover may include support bosses arranged to receive the elastic members, the means for positioning the cover and the bosses being distributed alternately around the X axis.

[70] - Said positioning means and said lid bosses can be arranged angularly according to a regular or irregular distribution around the X axis; [71] - In particular, a space between two immediately adjacent bosses of the lid may comprise a succession of at least two means for positioning said lid, in other words a succession of at least two protrusions between two immediately adjacent bosses;

[72] - The means for positioning the cylindrical skirt can form stiffeners, in order to guarantee anti-rotation of the cover relative to the cylindrical skirt;

[73] - The rotating element can receive an inertia ring at the level of the cylindrical skirt, in order to favor assembly on the cylindrical skirt rather than on the lid;

[74] The invention also relates, according to a second aspect, to a device according to any one of the preceding characteristics, said device being able to form a torsion damper. In particular, said device may be a dual mass flywheel comprising:

- a primary element, called primary flywheel, formed by said rotating element and said cover, said primary flywheel intended to be driven in rotation by a motor shaft,

- a secondary element, called secondary flywheel, able to cooperate with a driven shaft, and

- elastic members, elastically coupling in rotation the primary flywheel and the secondary flywheel.

[75] The advantage, according to the second aspect, is in particular to assemble the parts of the primary steering wheel end to end, without resorting to additional parts, to guarantee optimal compactness and greater manufacturing tolerance of the parts.

[76] The invention also proposes a method for assembling a device, according to a third aspect for a motor vehicle transmission chain, comprising at least the following steps: a) assembling a cylindrical skirt of a rotary element and a lid together, such that at least a first positioning means formed by the cylindrical skirt and at least a second positioning means formed by the lid associate with each other the other by complementarity of the shapes; b) Pressing and maintaining under axial pressure the cover and the cylindrical skirt against each other; c) Welding the first positioning means and the second positioning means together;

[77] According to this third aspect of the invention, the end-butted mechanical assembly of these parts is carried out by positioning and centering the cover on the cylindrical skirt, then then by welding operation, without any need for an additional operation of machining, post-operative finishing, or preparatory work for positioning the end of parts.

[78] Thanks to these characteristics, the means of positioning the two parts offer a greater geometric manufacturing tolerance, while avoiding problems of abutment between parts, resulting from assembly defects by laser welding. The tolerance at the level of part docking clearances is increased. The geometric constraints of the end-to-end surfaces, in particular their concentric flatness, are no longer required at the level of the parts to be assembled.

[79] Finally, the costs of such a process are therefore significantly reduced. The design and assembly of such parts are simplified and optimized.

[80] According to step b), the cooperation of said positioning means can be formed by deformed complementarity;

[81] According to step c), all of the means for positioning the two parts can be welded with a single weld bead, and also the cylindrical skirt and the cover, in a single welding operation;

[82] According to step c), the weld bead can be made with addition of material;

[83] Preferably, according to step c), the weld bead can be produced by arc welding, in particular by cold welding. The advantage of such an arc welding process (in English CMT, Cold Metal T ransfer) is to reduce the release of heat (principle of cold welding). This gain consequently reduces the deformations and increases the tolerance at the level of the docking clearances J, in particular at the level of the positioning means of the two parts. Therefore, it is no longer necessary to carry out preparatory work for the positioning of the cylindrical skirt and the cover, nor post-operative machining or finishing operations on these two parts; [84] Such an assembly method, according to a third aspect, can also have one or other of the characteristics described in the first and second aspects, combined with each other or taken independently of each other. In particular the cylindrical skirt of the rotary element and the cover can each comprise at least three positioning means preferably distributed angularly around the axis, in particular according to a regular distribution. Therefore, it is understood that the method of assembling the device comprises at least the following steps: a) assembling a cylindrical skirt of a rotary element and a cover with each other in such a way that first positioning means formed by the cylindrical skirt, preferably at least three, and that at least three second positioning means formed by the lid, preferably at least three, are associated with each other by complementary shapes; b) Bearing and maintaining under axial pressure the lid and the cylindrical skirt against each other; c) Welding of the first positioning means and the second positioning means with each other, in particular one by one.

[85] The invention will be better understood, and other boxwood, details, characteristics and advantages thereof will appear more clearly during the following description of a particular embodiment of the invention, given solely by way of illustrative and not limiting, with reference to the appended figures:

- [Fig. 1] is a perspective rear view of a device forming a torsion damper, according to a first embodiment of the invention;

- [Fig. 2] is an axial sectional view of the device, according to the first mode illustrated in [Fig. 1];

- [Fig. 3] is an exploded perspective view of the device, according to the first mode illustrated in [Fig. 1];

- [Fig. 4] is a detailed perspective view of the rotating element, according to the first mode illustrated in [Fig. 1];

- [Fig. 5] is a detailed perspective view of the lid, according to the first mode illustrated in [Fig. 1];

- [Fig. 6A], [Fig. 6B], [Fig. 6C] describe a method of assembling the device, according to the first mode illustrated in [Fig. 1];

- [Fig. 7] is an axial sectional view of the device, according to a second embodiment of the invention;

[86] “Vehicle” means motor vehicles, which include not only passenger vehicles, but also industrial vehicles, including heavy goods vehicles, public transport vehicles or agricultural vehicles, but also any transport vehicle allowing a living being and/or an object to pass from one point to another

[87] In the rest of the description and claims, the terms "lower / internal" or "external / external" with respect to the X axis and along a radial orientation, orthogonal to said axial orientation; and the terms "rear" AR and "front ¹ AV" to define the relative position of one element relative to another in the axial direction, an element intended to be placed close to the heat engine being designated rear and an element intended to be placed close to the gearbox being denoted by front

[88] Unless otherwise specified, “axially” means “parallel to the X axis of rotation of the balancing cover or the double clutch”; "radially" means "along a transverse axis intersecting the axis of rotation of the double wet clutch"; "angularly" or "circumferentially" means "around the X axis of rotation of the torsion damper device". The thickness is here measured along the X axis of rotation.

[89] There is shown in FIGURES 1 to 5 a first embodiment of a torsion damper 1 of a transmission chain, comprising in particular a device 10 of a transmission chain. This comprises a primary inertia flywheel 2, and a secondary flywheel 4, mounted in rotation relative to each other around the axis X. The torsion damper 1 also comprises elastic members 5, illustrated in FIGURE 2, which are arranged to transmit a torque and dampen rotational acydisms between the primary 2 and secondary 4 flywheels. Thus, the elastic members 5 are mounted between the primary flywheel 2 and the flywheel secondary inertia 20, and connecting them in rotation. [90] The primary flywheel 2 comprises a rotating element 3 intended to be fixed to the end of a crankshaft of an engine. In FIGURE 2, it comprises a hub 6, as well as a radial portion 7 which extends radially outwards from the hub 6 and a cylindrical skirt 8 of axial orientation which extends forwards AV from the outer periphery of the radial portion 7.

[91] The rotating element 3 is provided with holes, illustrated for example in FIGURE 2, allowing the passage of fixing screws, intended for fixing the rotating element 3 on the engine crankshaft. The primary flywheel 2, in particular the rotating element 3, is then fixed for example at the end of the engine shaft, to be driven in rotation by the engine crankshaft.

[92] Furthermore, the rotating element 3 can be fitted with a target, not shown, placed opposite a sensor, not shown. The sensor makes it possible to deliver a signal representative of the angular position and/or of the speed of the target. Such a sensor is in particular capable of informing the vehicle's computer of the position of the crankshaft, which enables the vehicle's computer to correctly control the injection of fuel and, for gasoline engines, the ignition of the spark plugs.

[93] Furthermore, the primary flywheel 2 also comprises a cover 9, of annular shape and axis X, which is fixed to the front end AV of the cylindrical skirt 8, as illustrated in the FIGURES 1 to 3. The cover 9 defines with the radial portion 7 and the cylindrical skirt 8, an annular chamber 30 in which the elastic members 5 are housed. The elastic members 5 are, for example, helical springs curved circumferentially distributed around the X axis.

[94] Each of the elastic members 5 extends circumferentially between two support tabs of a web 11, illustrated in dotted lines in FIGURE 2, integral in rotation with the secondary flywheel 4 and two support edges carried by the primary flywheel 2. Preferably, each support rim carried by the primary flywheel 2 is, for example, constituted by two bosses 12, 13 which are respectively formed in the cover 9 and in the radial portion 7 of the rotary element 3. The bosses 13 formed in the radial portion 7 of the rotary element 3 are shown in FIGURE 3 while the bosses 12 formed in the cover 9 are shown in FIGURES 1 and 3.

[95] The cover 9 comprises the bosses 12 which are each capable of forming, with a facing boss 13 formed in the radial portion 7 of the rotary element 3, a support rim for the elastic members 5.

[96] Thus, in operation each of the elastic members 5 bears, at a first end, against a support flange carried by the rotary element 3 and at a second end, against a support tab, not shown, carried by the veil 11, so as to ensure the transmission of the torque between the rotary element 3 and the secondary flywheel 4.

[97] According to an alternative embodiment not shown, the veil 1 1 is not directly attached to the secondary flywheel 4 but is rotatable about the X axis relative to the secondary flywheel 4. In In this case, the torque is transmitted between the veil 11 and the secondary flywheel 4 by one or more additional stages of elastic members.

[98] The secondary flywheel is intended to form the reaction plate of a clutch, not shown, connected to the input shaft of a gearbox. The secondary element 4 is centered and guided in rotation on the primary flywheel 2, in particular on the rotating element 3, by means of a bearing 14, such as a ball bearing, illustrated in the FIGURE 2.

[99] Furthermore, the device 1 comprises a protective ring 22 attached to the rotating element 3, to protect the annular ring gear of the starter against deformations which could damage it. In FIGURE 2, the cylindrical skirt 8 has a shoulder, formed in the rear edge of said cylindrical skirt 8, and in which the protection ring 22 is mounted. The protection ring 22 also comprises an axial protection portion 24 , constituted here by an annular bead which projects radially outwards with respect to the internal support portion. This axial protection portion 24 makes it possible to protect the cylindrical skirt 8 against impacts in the axial direction. The protection ring 22 is for example secured to the rotating element 3 by tight fitting, for example by hot fitting, in the shoulder, made in the rear edge of the cylindrical skirt 8.

[100] Furthermore, the cylindrical skirt 8 extends axially between two side faces, here between an internal face and an external face of the cylindrical skirt 8, along the axis X. A radial dimension Ep of the cylindrical skirt 8 is defined between its two internal and external lateral faces, that is to say that it is measured along a reference axis, here in the radial direction. [101] The inner face forms at its end an end edge 81 . The outer face forms at its end an end edge 82. The end edges 81, 82 delimit between them an outer periphery 15.

[102] The outer periphery 15 is preferably circumferentially continuous around the X axis.

[103] The internal face, in particular the end edge 81, can define a bearing face for the cover 9, and it defines an internal diameter D1 of the cylindrical skirt 8; while the end edge 82 defines an outer diameter of the cylindrical skirt 8.

[104] Furthermore, the primary flywheel 2 comprises a ring gear, not shown, for driving the primary flywheel 2 in rotation, using a starter. For example, the ring gear is made in one piece with the rotary element 3, that is to say made in one piece and in one piece with the cylindrical skirt 8, preferably at its axial end. For example, the ring gear may be defined by the outer periphery 15 of the cylindrical skirt 8.

[105] Alternatively the rotary element 3 comprises a ring gear added by welding against the front face AV of the cylindrical skirt 8, in particular formed on the end 15 of the cylindrical skirt 8. In all cases, it avoids having a ring gear on the cover 9, to limit its deformation and simplify its shape to the strict minimum.

[106] Furthermore, the cover 9 extends radially between a radially inner edge 91 and a radially outer edge 92, its simplified shape, in particular in section in the rectilinear form of the cover, limiting its size

The cover 9 can therefore be entirely contained in a plane P perpendicular to the axis X. In other words, the simplified shape of the cover is such that it exempts it from additional manufacturing steps, or even from portions depressed and axially offset Its radially outer edge 92 extends axially between two side faces 931 and 932, extending in the radial direction. The first side face 931 is located on the front AV of the cover 9, while the second side face 932 is located on the rear rear of the cover 9. The first and second side faces 931, 932 delimit at their radial end, a outer periphery 930, of the circular type. The outer periphery 900 defines an outer diameter D3 of the cover 9. A thickness Ec of the flange is defined axially between the side faces 931 and 932. The cover 9 has a thickness Ec, here of thin and/or substantially constant thickness.

[107] The cylindrical skirt 8 of the rotary element 3 here surrounds the cover 9. Thus the cover 9 is contained here entirely below the cylindrical skirt 8. The cover 9 is welded, at its radially outer edge 92, on the end edge 81 of the cylindrical skirt 8. In particular, the outer periphery 930 of the cover 9 rests on the end edge 81 of the cylindrical skirt 8, as illustrated in FIGURES 1, 2 and 6 .

[108] There are very small docking clearances J between the ends of parts 3, 9 to be welded, typically less than 1 mm, for example of the order of 0.5 mm, for which a mechanical assembly by laser welding has unacceptable defects.

[109] In order to simplify the end-to-end mechanical assembly of the cover 9 on the cylindrical skirt 8, positioning means 80, 90 are formed respectively from the inner end edge 81 of the cylindrical skirt 8 and from the outer periphery 930 of the cover 9, to position the cover axially with respect to the cylindrical skirt.

[110] The positioning means 80 of the cylindrical skirt 8 are formed in the inner diameter D1. It is therefore possible to define a first implantation circle C1, centered on the X axis, along which are arranged substantially the positioning means 80 of the cylindrical skirt 8. In particular, the positioning means 80 are delimited between the internal diameters D1 and exterior of the cylindrical skirt. The implantation circle C1 is also included between the outer and inner diameters D1 of the cylindrical skirt 8, and in particular at the level of the lower diameter D1 of the cylindrical skirt, as illustrated in the figures.

[111] In a variant not shown, the positioning means 80 can extend in the direction of the axis X. The first circle of implantation of the means for positioning the cylindrical skirt would therefore be between the internal diameter cylindrical skirt and the outside diameter of the lid. [112] The positioning means 90 of the cover 9 are formed from the outer diameter D3. It is therefore possible to define a second implantation circle C2, centered on the X axis, along which the positioning means 90 of the cover 9 are substantially arranged. In particular, the positioning means 90 can extend from the outer diameter D3 outwards, that is to say in the direction opposite to the axis X. Thus, the second implantation circle 02 may be equal to or greater than the outer diameter D3 of the cover 9, and in particular comprised between the outer diameter D3 of the cover 9 and the inner diameter D1 of the cylindrical skirt 8, as illustrated in the figures.

In particular, the outer diameter D3 of the cover 9 is substantially equal to the inner diameter D1 of the cylindrical skirt 8. The second implantation circle 02 can therefore be between the outer diameter D3 of the cover 9 and the inner diameter D1 of the skirt cylindrical 8. In a variant not shown, the positioning means 90 are formed within the lid, delimited by the inside diameter of the lid 9.

[113] Preferably, the positioning means 80, 90 of the cylindrical skirt 8 and the cover cooperate with each other. Therefore, the positioning means 80, 90 are positioned together along the X axis, and they are arranged to bear one on the other, to center the cover on the cylindrical skirt.

In the examples illustrated, the axial positioning, the centering and the angular indexing are carried out only at the same places of the cylindrical skirt and of the cover, via their positioning means 80, 90. Their joint cooperation of the positioning means 80, 90 is such that it can ensure both the axial holding, the centering and the angular indexing of said positioning means 90 with respect to said positioning means 80.

[114] Furthermore, the positioning means 80, 90 are then fixed together by welding, in particular by a single weld bead 100, which preferably results from arc welding. The weld bead 100 extends at least over 140 degrees around the X axis. Advantageously, the weld bead 100 extends continuously all around the X axis, that is to say over 360 degrees. Such a process, of the cold welding type, will be detailed in the remainder of the description.

[115] In the examples illustrated, the cover 9 and the cover are also welded together by said weld bead 100. The outer periphery 930 of the cover 9 thus bears against the internal side face 81 of the cylindrical skirt 8, in order to 'be fixed together by the weld bead 100. Therefore, the outer diameter D3 of the cover 9 coincides with the inner diameter D1 of the cylindrical skirt 8, said diameters D1, D3 being supported one on the other. As a result, the first and second circles C 1 , C2 for implantation of the positioning means 80, 90 of the cylindrical skirt and of the cover are also merged, so as to form a single and same circle of implantation.

[116] Furthermore, the positioning means 80 of the cylindrical skirt 8 are of complementary shape to that of the positioning means 90 of the cover 9, to manually index the cover on the cylindrical skirt.

[117] Preferably, the cylindrical skirt 8 comprises a limited number of means, here three positioning means 80 which are angularly distributed regularly around the axis X. The cover 9 comprises a limited number of means, here three positioning means 90 distributed angularly regularly around the axis X. In FIGURES 1 to 3, the positioning means 80, 90 are arranged axially opposite one another, ie one by one, their number being identical.

[118] Alternatively not shown, two positioning means 90 can cooperate with a positioning means 80, for example the number of cover positioning means being doubled compared to that of the cylindrical skirt.

[119] The positioning means 90 of the cover 9 are protrusions 95, that is to say solid portions formed from the outer diameter D3 of the cover 9, extending outwards, in the radial direction.

[120] The positioning means 80 of the cylindrical skirt 8 are bearing seats 85, that is to say hollow portions formed in the cylindrical skirt 8, in which the protrusions 95 are received. 'support' means a substantial housing whose resulting depth R1 is such that it is distinguished from a simple notch.

[121] In other words, the support seat 85 here comprises a distal portion 851 much further apart from the end edge of the cylindrical skirt 8, so as to be distinct from a proximal portion of the same seat 85. [122] The positioning means 80 of the cylindrical skirt 8 are thus formed in the thickness Ep of the cylindrical skirt 8. Each support seat 85 is a discontinuous shape such as a housing extending in the circumferential direction. In particular, a support seat extends radially along the depth R1, being open radially downwards, in order to accommodate a protrusion 95 therein. In addition, such a support seat 85 extends axially from the outer periphery 15, along a height H 1 , in order to form a housing of the open type here opening towards the front AV of the device 10, this for the insertion of the protuberance 95 in the support seat 85, and generally, the mounting of the cover 9 at the bottom of the cylindrical skirt 8. The depth R1 of a support seat 85 is defined radially from the internal diameter D1.

[123] In the examples illustrated, the support seats 85 are three in number, angularly distributed regularly around the axis X. The support seats 85 are of identical shape, here of identical depth R1 and height H 1 identical.

[124] Similarly, the protrusions 95 are three in number, regularly distributed angularly. The protrusions 95 are of identical shape, here of identical thickness and radial dimension. In particular, the shape of the protrusions 95 is delimited between the two side faces 931, 932 of the cover, in particular in FIGURES 1 to 6C.

[125] The support seats 85 are obtained by recess or stamping, at the specific places of the cylindrical skirt 8 providing them. This operation is carried out partially on the part, and not on the entire cylindrical skirt.

[126] Conversely, the protrusions 95 are obtained by limiting the recess or stamping operation to only the places on the cover that do not provide for protrusions. The portions then hollowed out or stamped together delimit the protrusions 95. This operation is also carried out partially on the part, and not on the entire cover.

[127] As a variant not shown, the bearing seats 85 and/or the protrusions 95 can be made by forging. They can also be made in press. The advantage here is to reduce the machining time, to produce one-piece parts with improved mechanical characteristics (respect of the fiber drawing, refining of the grain).

[128] In the examples illustrated, the support seat 85 has a stepped shape, hollowed out from the end edge 81 of the cylindrical skirt 8 along an axis which is orthogonal to the axis X of rotation, here in the radial direction.

[129] Preferably, each support seat 85 comprises:

- a distal part 851, defined with respect to the end edge 81 of the cylindrical skirt, called "bottom" of the support seat 85. This distal part 851 is defined by the diameter of one or more machining tools .

- the radial space between this distal part 851 with respect to the end edge 81 also defines a depth R1.

- the distal part 851 is connected to the end edge 81 of the skirt by a radial edge 852. The radial edge 852 is defined by the depth R1. The radial edge 852 is defined between the lower diameter D1 and the distal part 851 of the bearing seat 85.

[130] A distal portion 851 of the support seat 85 can be hollowed out to a greater depth R1 than a proximal portion of the same support seat 85. This distal part 851 delimits an inside diameter D1 along the X axis, which can correspond to half the tooling diameter for machining. As illustrated in the figures, this distal part 851 of the cylindrical skirt 8 ensures the centering of the cover radially with respect to the axis X.

[131] Therefore, the support seat 85 emerges radially on the inside of the device, in the direction of the X axis.

[132] The radial edge 852 of the bearing seat 85 is here defined axially with respect to the outer periphery 15, according to a height H 1 , produced during the machining operation by the tool. As illustrated in the figures, this radial part 852 of the cylindrical skirt 8 ensures the axial positioning of the cover 9. The geometric shape of the support seats therefore ensures reliable positioning and centering of the two parts which overlap one another. other after assembly.

[133] In particular, the support seat 85 having in cross section a shape of a semicircle.

[134] In particular, the positioning means 90 of the cover 9 are defined between the outer diameter D3 of the cover and the lower diameter D2 of the support seat. The depth R1 of the bearing seat 85 is defined between the lower diameter D1 of the cylindrical skirt and the lower diameter D2 of the bearing seat.

[135] Preferably, the depth R1 of the bearing seat 85 is between 25% and 60% of the radial dimension Ep of the cylindrical skirt 8, in the radial direction. In the examples illustrated, the depth R1 of the bearing seat 85 is approximately 43% the radial dimension Ep of the cylindrical skirt 8. [136] In particular, the radial edge 852 forms with the distal part 851 an angle a, comprised between 45 degrees and 120 degrees, in particular between 90 and 120 degrees, in a variant not illustrated. In the examples illustrated, the angle a is substantially 90 degrees. The positioning means 80 of the cylindrical skirt 8 are formed by the distal part 851 and the radial edge 852 of the support seat 95. The angle a can depend on the edge of the tooling used in the machining process.

[137] As a variant not shown, the angle a may be strictly greater than 90 degrees, in order to incline the radial edge relative to the bottom of the support seat.

[138] By way of example in FIGURE 4, the radial edge 852 is connected to the distal part 851 by a fillet 853, for example an arc of a circle, which results from the machining operation of the seat of support 95, for example the head of the tool used. Note that a support seat can be machined by several machining tools of the same range, of different diameters, in order to gain machining precision for the support seat. In particular, the distal part 851 of the support seat is here formed by a first and a second hollow section 851', 851', of slightly different diameters, produced by different machining heads. During the machining operation, the first hollowed-out section 851' of the bottom 851 is produced by a first tool of larger diameter, while the second hollowed-out section 851' of the bottom 851 is produced by a second tool of smaller diameter. The second hollow section 851” here receives the entire protrusion 95, and it defines the inside diameter D3 along the X axis.

[139] In FIGURES 2 and 4, the maximum depth R1 of the support seat is defined by the furthest point from the X axis, belonging here to the second recessed section 851”. As a variant, this point can belong to the first hollowed-out section 851'. Furthermore, each protrusion 95 comprises several bearing faces 950, 951, 952 arranged to be received inside the bearing seat 95.

[140] In detail, a protrusion 95 extends along the X axis between two side faces 951, 952. The side face located on the front AV of the protrusion 95 defines a first bearing face 951, which jointly receives in part (with the distal part 851) the weld bead 100. The distal part 851 of the bearing seat and the first bearing face 951 of the protrusion are arranged together to fix the positioning means 80, 90 together to complete the mechanical assembly of the device 1. The first bearing face 951 can define the angle a with the distal part 851.

[141] The side face located on the rear rear of the protrusion 95 defines a second bearing face 952 of the protrusion 95, which rests or abuts on the radial edge 852 of the support seat 95 The radial edge 852 here makes it possible to position and hold the protrusions 95 of the cover 9 within the cylindrical skirt 8. The radial edge 852 of the bearing seat 85 and the weld bead 100 are arranged axially on either side of the other of the cover 9, so as to make together the protrusion 95 of the cover 9 fixed axially and angularly with respect to the support seat 85 of the cylindrical skirt 8. Therefore, by defining a plane P, orthogonal to the axis X and passing through the cover, the radial edge 852 and the weld 100 are arranged axially on either side of the plane P, respectively arranged at the rear rear and the front front of the plane P.

[142] The first and second bearing surfaces 951, 952 axially define between them the radially outer end 950 of the protuberance 95, which rests on the distal part 851 of the bearing seat 95. The distal part 851 of the support seat 85 makes it possible to center the protrusions 95 of the cover 9 relative to the cylindrical skirt 8.

[143] The distal part 851 is sized to receive the end 950 of the protrusion 95 and the weld bead 100. The end 950 can be a flat or smooth bearing surface.

[144] In particular, the end 950 defines an outer diameter D4 of the protrusion 95. The first and second bearing faces 951, 952 are defined between the outer diameter D3 of the cover and the outer diameter D4. In other words, once the end 950 of the protrusion 95 is mounted in support on the distal part 851 of the support seat, the remaining space of the distal part 851, called "free space" of the bottom of the seat support, then partly receives the weld bead 100. This free space, formed in the support seat 85, is defined axially between the first support face 951 and the outer periphery 15 of the cylindrical skirt. In particular, the outer diameter D4 is substantially equal to the inner diameter D3. [145] In the examples illustrated, the bearing seats 85 and the protrusions 95 here are of complementary shapes, of the cooperation type of male-female shapes illustrated in FIGURES 1 to 5. Any type of cooperation of known male-female shapes is possible.

[146] In particular in FIGURE 5, each protrusion 95 is of convex shape, that is to say of male shape with a rounded edge 950 extending in the direction of the support seat 85. Therefore, the contours first and second bearing surfaces 951, 952 are of circular shapes, preferably identical, such as semicircles. The end 950 of the protrusion 95 is rounded in shape, like a half-cylinder. As a variant not shown, the end may be in the shape of a half-sphere.

[147] In particular in FIGURE 4, each support seat 85 is of concave shape, that is to say of female shape with a rounded edge 950 receiving the outgrowth 95 of convex shape, in other words a recess in hollow semi-cylinder shape. Therefore, the contour of the radial edge 852 is circular in shape, like a half-moon. The distal part 851 of the support seat 85 is rounded in shape, like a hollow half-cylinder.

[148] As a variant not shown, the bottom can be in the shape of a hollow half-sphere.

[149] As a variant not shown, the cooperation of male-female shapes can be applied, mutatis mutandis, to means for positioning the cylindrical skirt 8 which would be of male shape, and means for positioning the lid which would be of shape female. All the characteristics described for one part then apply to the other part.

[150] In the first embodiment, the second bearing face 952 of the protrusion 95 is formed in a groove 96 of the protrusion. The groove 96 is made by machining or stamping. The groove 96 can be defined relative to the rest of the cover 9. It ensures better cooperation of the protrusion 95 with the radial edge 852 of the support seat.

[151] By way of example in FIGURE 5, the groove 96 is formed on the protrusion 95 and the radially outer edge 92 of the cover 9. The groove 96 is formed along the axis X, and it extends axially from the second side face 932 of the cover 9. The groove 96 extends radially from the radially outer edge 92 to the end 950 of the protrusion 95, along a radial dimension R2. Preferably, the groove 96 and the radial edge 852 of the support seat are of complementary shapes.

[152] In particular, the radial dimension R2 of the groove 96 is strictly greater than the depth R1 of the support seat, for example here the radial dimension R2 is here half the depth R1 of the support seat. This facilitates manual assembly, forming an additional clearance to assemble the protrusion 95 in the support seat 85.

[153] As an example in FIGURE 5, the groove 96 extends angularly between the edges 960 which are formed on the radially outer edge 92 of the cover 9.

[154] We will now describe the method of assembling the device 1, as illustrated in the first embodiment, in particular in FIGURES 1 to 6C, which comprises at least the following steps:

- According to a first step (illustrated in FIG. 6A), a rotary element 3 is provided, comprising a cylindrical skirt 8 of axis X of revolution comprising positioning means 80. A cover 9 is also provided comprising positioning means 90 adapted to cooperate jointly with the positioning means 80 of the rotary element 3.

- According to a second step (illustrated in FIG. 6B), the lid 9 is supported and maintained under axial pressure on the cylindrical skirt 8 of the rotary element 3, in particular by causing the positioning means 80 of the cylindrical skirt to cooperate 8 with the positioning means 90 of the lid 9.

- According to a third step (illustrated in FIG. 6C), the positioning means 80, 90 of the cylindrical skirt 8 and of the cover 9 are welded, in particular, by means of a weld bead 100, produced in particular by welding Cold.

[155] In particular according to the third step, the positioning means 80, 90 are welded together, jointly advantageously thanks to their complementarity of shapes, preferably, to achieve both the axial holding, the centering and the angular indexing of said means of the lid relative to those of the cylindrical skirt. [156] In particular according to the third step, the cylindrical skirt 8 of the rotary element 3 and the cover 9 are additionally welded. Therefore, the contours of all the parts 3, 9, in particular the contours of their positioning means are welded. According to a fourth additional step, the bearing pressure exerted on the cover 9 can be released and/or the assembly cooled, in particular at the level of the weld bead 100.

[157] In particular according to the third step, the weld bead 100 is produced by arc welding, in particular by cold welding (in English CMT, Cold Metal T ransfer). Such a method makes it possible to weld the two parts 3, 9, of thin thickness or having a certain profile, with significant docking clearances J between them, which would have proved problematic for an end-to-end laser weld. precision, the filler metal is thus deposited with precision between the cover and the cylindrical skirt of the rotating element, by interrupting the short arc in a targeted manner (known as short circuits). The positioning means 80, 90 of the cylindrical skirt 8 and of the cover 9 will then be welded or brazed edge-to-edge, in a perfectly uniform manner and free from projections. The releases of heat and the deformations are reduced, in particular at the level of the positioning means 80, 90 of the two parts.

[158] It is then no longer necessary to carry out preparatory work for the positioning of the cylindrical skirt 8 and the cover 9, nor post-operative machining or finishing operations on these two parts 3, 9.

[159] Has been described in FIGURE 7, a second embodiment of the invention substantially similar to the first embodiment, except that the second bearing face 952 of the protrusion 95 is formed in a rib 96' from the outgrowth. Rib 96' can be defined relative to the rest of cover 9.

[160] In the second mode, the rib 96' is also produced by stamping or machining the rest of the cover 9. It ensures better cooperation of the protuberance 95 with the radial edge 852 of the bearing seat 85. The rib 96 'is formed on the protrusion 95 and the radially outer edge 92 of the cover 9. The rib 96' is formed along the X axis, and it extends axially from the second side face 932 of the cover 9. The rib 96' extends radially from the radially outer edge 92 to the end 950 of the protrusion 95, along a radial dimension R2.

[161] In particular in FIGURE 7, the rib 96' and the radial edge 852 of the support seat are of complementary shapes. Advantageously, the radial edge 852 can comprise for example a groove, formed in the cylindrical skirt 8, which is intended to receive the rib 96' of the protrusion 95. Their shapes are then complementary.

[162] In particular, the radial dimension R2 of the rib 96' is strictly greater than the depth R1 of the support seat, for example here the radial dimension R2 is here half the depth R1 of the support seat. This facilitates manual assembly, forming an additional clearance to assemble the protrusion 95 in the support seat 85.

[163] As an example in FIGURE 7, the groove 96 extends angularly between the flanges 960 'which are formed on the radially outer edge 92 of the cover 9.

[164] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if those -these fall within the scope of the invention. In particular, if the invention has been described above in relation to a device of the torsion damper type, a device as described above can also be associated with other types of device, such as a flywheel , rigid or flexible, a torque converter or others.

[165] The use of the verb "to comprise", "to understand" or "to include" and of its conjugated forms does not exclude the presence of other elements or other steps than those set out in a claim. In the claims, any reference sign in parentheses cannot be interpreted as a claim limitation.

Claims

[Claim 1] [Device (10) for a motor vehicle transmission chain, comprising:

- a rotary element (3) intended to be mounted in rotation around an axis (X) of rotation, the rotary element (3) comprising a radial extension portion (7) and a cylindrical skirt (8) which is extends from the radial extension portion (7),

- a cover (9) of annular shape, arranged with the rotary element (3) to enclose elastic members (5), in which the cylindrical skirt (8) and the cover (9) each comprise positioning means (80 , 90) cooperating together so as to position the cover (9) on the rotating element (3), said positioning means (80, 90) of the cylindrical skirt (8) and of the cover (9) being fixed together by welding .

[Claim 2] Device (10) according to the preceding claim, in which the means (90) for positioning the cover (9) are arranged substantially along an implantation circle (C2) which is included in particular between the outer diameter (D2) of the cover (9) and the inside diameter (D1) of the cylindrical skirt (8).

[Claim 3] Device (10) according to claim 1 or 2, in which the cylindrical skirt (8) surrounds the lid (9), the positioning means (90) of the lid (9) being formed from the external diameter (D3 ) of the lid.

[Claim 4] Device (10) according to any one of the preceding claims, in which the cylindrical skirt (8) and the cover (9) each comprise at least three positioning means (80, 90) distributed angularly around the axis (X) of rotation, the positioning means (80, 90) being made by stamping or by machining respectively the rotary element and the cover.

[Claim 5] Device (10) according to any one of the preceding claims, in which the positioning means (80, 90) of the cylindrical skirt (8) and of the cover (9) are fixed together by a weld bead ( 100), the weld bead (100) extending at least partially around the axis (X) of rotation.

[Claim 6] Device (10) according to the preceding claim, in which the weld bead (100) extends continuously around the axis (X) of rotation, over 360 degrees.

[Claim 7] Device (10) according to any one of Claims 5 to 6, in which the weld bead (100) is produced by welding with addition of material, for example by arc welding, preferably by welding cold.

[Claim 8] Device (10) according to any one of the preceding claims, in which the cylindrical skirt (8) forms at least two bearing seats (85), the cover (9) forming at least two protrusions (95) , the cylindrical skirt (8) and the cover (9) cooperating by positioning said projections on said respective bearing seats.

[Claim 9] Device (10) according to the preceding claim, in which a protuberance (95) is of complementary shape to that of a support seat (85).

[Claim 10] Device (10) according to any one of Claims 8 to 9, in which the projections (95) of the cover (9) are of convex shapes, and the bearing seats (85) of the rotary element (3) are concave in shape.

[Claim 11] Device (10) according to any one of Claims 8 to 10, in which the cylindrical skirt (3) has a maximum thickness (Ep) measured along a reference axis, and the bearing seat (85) has a depth (R1) measured along another axis parallel to the reference axis, the depth (R1) being between 25% and 65% of the maximum thickness (Ep).

[Claim 12] Device (10) according to any one of claims 8 to 11, wherein the support seat (85) has a stepped shape, hollowed out from an end edge (81) of the skirt cylindrical (8) along an axis which is orthogonal to the axis (X) of rotation, a distal portion (851) of the support seat (85) being hollowed out to a greater depth (R1) than a proximal portion of the same support seat (85), the support seat (85) having in cross section the shape of a semi-circle.

[Claim 13] Device (10) according to any one of claims 8 to 12, wherein the protrusion (95) comprises several bearing surfaces (950, 951, 952) intended to be received on a bearing seat (85), one of the bearing faces (952) of the excrescence (95) being formed in a groove (96) or a rib (96') of the excrescence (95), said groove (96) or rib (96') cooperating with the end edge (81) of the cylindrical skirt (8) and/or with the bearing seat (85).

[Claim 14] Device (1) according to any one of the preceding claims, in which the said device (1) is a double mass flywheel (1) comprising:

- a primary flywheel (2), formed by said rotating element (3) and said cover (9), said primary flywheel being intended to be driven in rotation by a driving shaft

- a secondary flywheel (4) capable of cooperating with a driven shaft, and

- the elastic members (5), elastically coupling in rotation the primary flywheel (2) and the secondary flywheel (4).

[Claim 15] Method of assembling a device (1) for a motor vehicle transmission chain, comprising at least the following steps: a) assembling a cylindrical skirt (8) of a rotary element (3) and a cover (9) with each other such that at least three first positioning means (80) formed by the cylindrical skirt (8) and at least three second positioning means (90) formed by the lid (9) associate with each other by complementarity of forms; b) Bearing and maintaining under axial pressure the cover (9) and the cylindrical skirt (8) against each other; c) Welding of the first positioning means (80) and the second positioning means (90) with each other. !