Torsion damper

Abstract

Torsion damper (1) for a torque transmission device comprising: a torque input element (2) and a torque output element (3) rotatable about an axis of rotation (X); elastic members (4) elastically coupling the torque input element to the torque output element in rotation; and a web (5) configured to cooperate with the elastic members, the web comprising a plurality of axially stacked layers (51, 52), each layer comprising at least two radially extending drive arms (521, 521) to be positioned circumferentially between two elastic members, the layers being connected together by their drive arms by a connecting means (6). (Abstract Figure: 1)

Description

Title of the invention: Torsion damper Technical field

[0001] The present invention relates to the field of torque transmission devices of the torsion damper type, in particular intended to be arranged in the transmission chain of a vehicle, between an internal combustion engine and a gearbox. Technological background

[0002] Internal combustion engines do not generate a constant torque and exhibit acyclisms caused by the successive explosions in their cylinders. These acyclisms generate vibrations which are likely to be transmitted to the gearbox and thus cause shocks, noise and sound pollution, which are particularly undesirable. In order to reduce the undesirable effects of vibrations and improve the driving comfort of motor vehicles, it is known to equip motor vehicle transmissions with torsion dampers. Such torsion dampers are used in particular in double damped flywheels (DVA), clutch frictions, or lock-up clutches for torque converters, also called "lock-up" clutches.

[0003] Double damping flywheels generally comprise a primary flywheel and a secondary flywheel which are rotatable relative to each other and elastically coupled to each other by elastic members. The rotational drive of the elastic members is achieved via a web. The web comprises a central annular portion fixed to the secondary flywheel and drive arms which extend radially outwards to press against the ends of the elastic members.

[0004] Document DE102004024747 discloses a double damping flywheel where the web is produced by a structure composed of several axially stacked discs connected to each other in their central annular part by rivets. This structure of stacked discs, by the use of several discs of identical geometry, makes it possible to produce the web by a simpler and more economical process than a web of monobloc structure.

[0005] However, such a sail structure composed of stacked discs connected to each other by their central annular part poses several technical problems, in particular insufficient mechanical strength due firstly to excessive deformation of the drive arms under overtorque stresses which may be generated in the transmission chain, and secondly to a degradation of the support quality of the drive arms on the elastic organs due to the positioning defects of the discs between them. Summary

[0006] In all that follows, ordinal numeral adjectives are used to differentiate characteristics. They do not define the position of a characteristic. Therefore, for example, a third characteristic of a product does not mean that the product has a first and / or a second characteristic.

[0007] An idea underlying the invention is a torsion damper which makes it possible to solve one or more technical problems of the prior art, for example the aforementioned problems.

[0008] The invention relates to a torsion damper for a torque transmission device, in particular for a vehicle transmission chain, the torsion damper comprising: • a torque input element and a torque output element rotatable relative to each other about an axis of rotation; • elastic members elastically coupling in rotation the torque input element to the torque output element; and • a web configured to cooperate in rotation with the elastic members;

[0009] the web comprising a plurality of axially stacked layers, the plurality of layers comprising a first layer comprising at least two first drive arms and a second layer comprising at least two second drive arms, the at least two first drive arms and the at least two second drive arms extending radially to be positioned circumferentially between two elastic members, the at least two first drive arms being connected to the at least two second drive arms by a connecting means.

[0010] This sail structure composed of several stacked layers makes the process for obtaining the sail simple and economical by the possibility of using a thin sheet metal for each layer, which makes it easy to cut and requires cutting tools, for example press cutting tools, which are less expensive and less complex than cutting tools used in the case of a thick single-piece sail.

[0011] The connection by a connecting means of the at least two first drive arms with the at least two second drive arms makes it possible to increase the mechanical resistance under torque of the web. Indeed, by forcing the drive arms to work mechanically together, this connection has the effect of increasing the bending stiffness and therefore of significantly reducing the deformations under torque.

[0012] The connection by a connecting means of the at least two first drive arms with the at least two second drive arms also has the advantage of connecting the drive arms in an area located in the immediate vicinity of the elastic members. Thus the relative positioning defects of the drive arms are reduced, which makes it possible to ensure simultaneous contact of all the drive arms with the elastic members, thus guaranteeing good support quality.

[0013] Finally, the connection by a connecting means of the at least two first drive arms with the at least second drive arms makes it possible to bring together the stacked layers in a single subassembly, which makes the handling and assembly of the web easier in the different stages of manufacturing the torsion damper.

[0014] For the purposes of this application: • “axially” means “parallel to the axis of rotation”; • “radially” means “along an axis belonging to a plane orthogonal to the axis of rotation and intersecting this axis of rotation”; • “circumferentially” means “around the axis of rotation”;

[0015] According to an additional characteristic of the invention, the connecting means is a rigid fixing.

[0016] Rigid fixing means a fixing which makes it possible to immobilize the at least first layer with the at least second layer.

[0017] According to an additional characteristic of the invention, the connecting means is a riveting connection.

[0018] The riveting connection has the advantage of being a simple and economical assembly process to implement. In addition, the axial crushing of the rivets during the riveting operation induces a progressive radial deformation of the rivets inside the holes made in the drive arms, which ultimately causes the layers of the web to center and align with each other.

[0019] According to an additional characteristic of the invention, the connecting means is a connection by welding, in particular a connection by electrical resistance welding or by laser welding, in particular by transparency laser welding.

[0020] The welding connection has the advantage that no additional components are required to connect the drive arms. This allows for cost savings but also allows for a more axially compact footprint, particularly in the cases of electric resistance welding (also called spot welding) or laser welding, the welding processes of which do not require any material input.

[0021] According to an additional characteristic of the invention, the connecting means is a connection by gluing or by crimping or by screwing or by clinching.

[0022] According to an additional characteristic of the invention, the connecting means is a connection by a non-metallic material with vibration absorption capacity, in particular an elastomeric material.

[0023] According to an additional characteristic of the invention, the connecting means is positioned radially such that a circular cylindrical surface having as its axis of revolution the axis of rotation passes through both the connecting means and the elastic members.

[0024] According to an additional characteristic of the invention, the first layer and the second layer are made of steel which has undergone a hardening treatment, in particular a hardening treatment making it possible to obtain a surface hardness of 300 to 800 HV.

[0025] According to an additional characteristic of the invention, the first layer and the second layer are each made from a steel sheet having a constant thickness, in particular from a steel sheet having a constant thickness of between 0.8 and 3 mm.

[0026] According to an additional characteristic of the invention, the number of layers is between 2 and 7.

[0027] These last three characteristics make it possible to reduce the cost and mass of the web by the fact that a thin sheet metal which has undergone a hardening treatment has a mechanical resistance up to 25% greater than a thicker sheet metal which has undergone the same hardening treatment. For example, a single-piece web having a thickness of 5 mm can advantageously be replaced by a web comprising 4 stacked layers each having a thickness of 1 mm.

[0028] According to an additional characteristic of the invention, each layer comprises between 2 and 6 drive arms.

[0029] According to an additional characteristic of the invention, the first layer further comprises a first connection zone and the second layer further comprises a second connection zone, the first connection zone and the second connection zone being configured to be fixed on the torque input element or on the torque output element.

[0030] Thus, the connection zones make it possible to ensure a mechanical connection between the layers of the web and the torque input element or the torque output element on which they are fixed. The connection zones may in particular comprise holes into which the fixing rivets and / or axial bearing surfaces are inserted.

[0031] According to an additional characteristic of the invention, the first connection zone and the second connection zone are axially in contact and are fixed together on the torque input element or on the torque output element.

[0032] According to a first aspect of the invention, the at least two first arms drive arms extend radially outwardly relative to the first connection area and the at least two second drive arms extend radially outwardly relative to the second connection area.

[0033] According to another aspect of the invention, the at least two first drive arms extend radially inwardly relative to the first connection area and the at least two second drive arms extend radially inwardly relative to the second connection area.

[0034] According to an additional characteristic of the invention, the at least two first drive arms and / or the at least two second drive arms are connected together by a strip of material extending circumferentially, said strip of material being positioned radially outside and / or inside the at least two first drive arms and the at least two second drive arms.

[0035] According to an additional characteristic of the invention, the first layer and the second layer are segmented circumferentially into a plurality of segments, each segment extending circumferentially over a first angle, in particular a first angle of between 15° and 220°.

[0036] The circumferentially segmented layers make it possible to reduce the quantity of material used for the manufacture of the web. Indeed, the segmentation makes it possible to optimize the relative position of several segmented layers in a strip of sheet metal from which they are cut in order to limit the width of said strip of sheet metal as well as reduce the resulting material waste.

[0037] According to an additional characteristic of the invention, the first layer and the second layer extend circumferentially over a second angle between 195° and 360°, preferably over a second angle between 195° and 270°.

[0038] This latter characteristic is an alternative solution for reducing the quantity of material used for the manufacture of the veil.

[0039] According to one aspect of the invention, the first layer and the second layer are flat.

[0040] Flat layers allow for reduced cost and easier manufacturing because the geometry of the layers can be obtained by a simple and unique operation of cutting the external contours from a metal sheet.

[0041] According to another aspect of the invention, the at least two first drive arms are axially offset from each other by an axial distance, and the at least two second drive arms are axially offset from each other by said axial distance, so that the first layer and the second layer are axially nested.

[0042] This latter characteristic makes it possible to obtain a sail structure comprising layers which separately extend circumferentially over a second angle of between 195° and 270°, and which, when assembled together in an imbricated manner, axially provide coverage over a total angle of 360° of the connection areas on the torque input element or on the torque output element, thus allowing a rigid and robust fixation of the web.

[0043] According to an additional characteristic of the invention, the axial distance is equal to the thickness of the sheet from which the first layer and the second layer are made.

[0044] Thus, the first connection zone and the second connection zone are located on the same axial plane, which facilitates the attachment of the web to the torque input element or the torque output element.

[0045] According to an additional characteristic of the invention, the first layer and the second layer are of identical geometry.

[0046] This latter feature allows for cost reduction through standardization of the web manufacturing. Since the stacked layers of the web are of identical geometry, it is possible to use the same layer geometry on several different vehicle applications, adapting the number of layers according to the torque capacity required for each vehicle application.

[0047] According to one aspect of the invention, the elastic members of the torsion damper are straight helical springs.

[0048] According to another aspect of the invention, the elastic members of the torsion damper are curved helical springs.

[0049] According to another aspect of the invention, the elastic members of the torsion damper are helical springs arranged in series.

[0050] According to another aspect of the invention, the elastic members of the torsion damper are helical springs arranged in series, the web being configured to ensure the phasing of the rotational movement around the axis of rotation of said helical springs arranged in series.

[0051] These last four characteristics make it possible to adapt the type of springs according to the torsional stiffness targeted for the torsion damper in order to ensure sufficient filtration of torsional oscillations.

[0052] According to an additional characteristic of the invention, the torsion damper comprises a pendulum damping device.

[0053] According to an additional characteristic of the invention, the torsion damper comprises a pendulum damping device supported by the web.

[0054] According to an additional characteristic of the invention, the torsion damper comprises a pendulum damping device supported by the web, the pendulum damping device comprising a pendulum body comprising two oscillating masses arranged axially on either side of the web, the two oscillating masses being paired together by at least one spacer, the at least one spacer passing axially in a first opening provided in the at least first layer and in a second opening provided in the at least second layer.

[0055] According to an additional characteristic of the invention, the torsion damper is a double damping flywheel comprising a primary mass comprising the torque input element in the form of a primary flywheel intended to be driven in rotation by a driving shaft, a secondary mass comprising the web and the torque output element in the form of a secondary flywheel or a hub capable of cooperating, directly or via a clutch, with a driven shaft, and the elastic members in the form of a plurality of springs elastically coupling in rotation the primary mass and the secondary mass.

[0056] The invention further relates to a torque transmission device, in particular for a vehicle transmission chain, comprising a torsion damper as defined above and a clutch. Brief description of the figures

[0057] [Fig-1] [Fig.l] is a broken sectional view of a torsion damper along a first embodiment of the invention.

[0058] [Fig.2] [Fig.2] is a cutaway perspective view of a torsion damper according to the first embodiment of the invention.

[0059] [Fig.3] [Fig.3] is a partial perspective view of a torsion damper according to the first embodiment of the invention.

[0060] [Fig.4] [Fig.4] is a perspective view of a web of a torsion damper according to the first embodiment of the invention.

[0061] [Fig.5] [Fig.5] is a perspective view of a web of a torsion damper according to a second embodiment of the invention.

[0062] [Fig.6] [Fig.6] is a perspective view of a web of a torsion damper according to a third embodiment of the invention.

[0063] [Fig.7] [Fig.7] is a perspective view of a web of a torsion damper according to a fourth embodiment of the invention.

[0064] [Fig.8] [Fig.8] is a perspective view of a layer of a web of a torsion damper according to the fourth embodiment of the invention.

[0065] [Fig.9] [Fig.9] is a side view of a layer of a web of a torsion damper according to the fourth embodiment of the invention.

[0066] [Fig. 10] [Fig. 10] is a front view of a web layer of a torsion damper according to the fourth embodiment of the invention. Description of the embodiments

[0067] In all the figures, elements that are identical or provide the same function bear the same reference numbers. The following embodiments are examples. Although that the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment or that the features apply only to a single embodiment. Single features of different embodiments may also be combined or interchanged to provide other embodiments.

[0068] Figures 1 to 3 represent a torsion damper 1 according to a first embodiment of the invention. The torsion damper 1 is here a double damping flywheel comprising a primary mass and a secondary mass. The torsion damper 1 comprises a torque input element 2, here in the form of a primary flywheel 2, intended to be fixed to the end of a driving shaft, such as a crankshaft of a combustion engine, not shown. The torsion damper 1 comprises a torque output element 3, here in the form of a secondary flywheel 3 intended to receive a clutch linked in rotation to the input shaft of a gearbox, not shown. This torsion damper configuration is suitable for a transmission chain of a thermal vehicle provided with a manual gearbox.

[0069] In another embodiment of the invention not shown, the torque output element 3 of the torsion damper 1 may be in the form of a hub comprising an internal spline linked in rotation to the input shaft of a gearbox. This torsion damper configuration is particularly suitable for a transmission chain of a hybrid vehicle.

[0070] In the first embodiment of Figures 1 to 3, the primary mass is composed of the primary flywheel 2 on which is fixed, in particular by a welding process, a cover 7. Thus, the primary flywheel 2 and the cover 7 can be arranged to delimit a chamber capable of receiving elastic members 4 and to contain a lubricant, preferably grease or oil. In addition, the primary flywheel 2 can carry, on its outer periphery, a toothed crown 11 for driving the primary mass in rotation using a starter.

[0071] In the first embodiment of Figures 1 to 3, the secondary mass is composed of the secondary flywheel 3 on which can be fixed, via secondary rivets 9, a web 5 configured to cooperate in rotation with the elastic members 4. The secondary mass can also comprise a first sealing washer 12 and a second sealing washer 14 fixed axially on either side of the web 5 via the secondary rivets 9 and extending radially outwards to rub on the cover 7. Thus constituted, the first sealing washer 12 and the second sealing washer 14 can ensure the maintenance of the lubricant in the chamber of the primary mass. In order to limit friction and wear, a first friction washer 13 and a second friction washer 15, preferably made of plastic, can be arranged between the cover 7 and the first sealing washer 12 and the second sealing washer 14 respectively.

[0072] The primary flywheel 2 and the secondary flywheel 3 are rotatable relative to each other about an axis of rotation X. In order to ensure their rotational guidance, a bearing 10, for example in the form of a ball bearing or a plain bearing, may be arranged between a primary hub 8 fixed on the radially internal part of the primary flywheel 2 and the secondary flywheel 3.

[0073] The elastic members 4 elastically couple in rotation the primary flywheel 2 and the secondary flywheel 3. As illustrated in [Fig. 3], the elastic members 4 can be formed by a first set of two concentric curved springs and by a second set of two concentric curved springs. Each of the first ends of the first set and of the second set is mounted in circumferential abutment against the primary flywheel 2 and the cover 7, and each of the second ends of the first set and of the second set is mounted in circumferential abutment against the disc 5.

[0074] In another embodiment of the invention not shown, the elastic members 4 may be formed by a number of sets of springs greater than two, for example a number of sets of springs equal to three or four. In another embodiment of the invention not shown, the springs may be straight helical springs, in particular straight helical springs working in series.

[0075] In the various embodiments according to the invention of Figures 1 to 10, the web 5 comprises a plurality of axially stacked layers 51, 52, the plurality of layers comprising a first layer 51 comprising at least two first drive arms 511 and a second layer 52 comprising at least two second drive arms 521, the at least two first drive arms 511 and the at least two second drive arms 521 extending radially to be positioned circumferentially between two elastic members 4, the at least two first drive arms 511 being connected to the at least two second drive arms 521 by a connecting means 6.

[0076] As illustrated in particular in [Fig. 4], the layers 51, 52, 53, 54, 55 may further comprise connection zones 512, 522, 532, 542, 552 configured to be fixed to the secondary flywheel 3. The connection zones 512, 522, 532, 542, 552 may comprise circular holes into which the secondary rivets 9 are inserted. The connection zones 512, 522, 532, 542, 552 may also comprise axial bearing surfaces on the secondary flywheel 3.

[0077] According to an alternative embodiment not illustrated, the layers of the web 5 are not fixed to the secondary flywheel 3 but are mobile in rotation relative to said secondary flywheel 3 and the torque is transmitted between the web 5 and the flywheel secondary 3 by one or more additional stages of elastic organs.

[0078] As illustrated in the first embodiment of the invention of [Fig.4], the web 5 may comprise five layers 51, 52, 53, 54, 55 of identical geometries. The five layers 51, 52, 53, 54, 55 may be flat and each comprise two drive arms 511, 521, 531, 541, 551 which extend radially outwards. The drive arms 511, 521, 531, 541, 551 are connected together by a connecting rivet 61. The drive arms 511, 521, 531, 541, 551 are provided with a circular hole into which the connecting rivet 61 is inserted. By way of illustration, the five layers 511, 521, 531, 541, 551 here have a thickness of 1.2 mm and can be made from a steel having a surface hardness of between 420 and 475 HV.

[0079] As illustrated in the second embodiment of the invention of [Fig. 5], the web 5 may comprise three layers 51, 52, 53 of identical geometries. The three layers 51, 52, 53 may be flat and each comprise two drive arms 511, 521, 531 which extend radially outwards. The drive arms 511, 521, 531 are connected together by a weld 62, in particular a resistance weld or spot weld. In [Fig. 5], the weld 62 is shown schematically to symbolize a heat-affected zone following contact with the electrodes of the welding process. By way of illustration, the three layers 511, 521, 533 here have a thickness of 1.5 mm and may be made of a steel having a surface hardness of between 405 and 463 HV.

[0080] As illustrated in the third embodiment of the invention of [Fig. 6], the web 5 may comprise layers 51, 52, 53, 54, 55 each circumferentially segmented into segments. The segments of the layers 51, 52, 53, 54, 55 may each extend circumferentially over a first angle a of between 15° and 220°. Here, the web 5 may comprise five identical, flat layers 51, 52, 53, 54, 55, segmented into two segments and each comprising two drive arms 511, 521, 531, 541, 551. The segments of each layer are distinct and may be fixed separately in packs on the secondary flywheel 3. The drive arms 511, 521, 531, 541, 551 of each pack are connected together by a connecting rivet 61.

[0081] As illustrated in the fourth embodiment of the invention of Figures 7 to 10, the web 5 may comprise two layers 51, 52 which each extend circumferentially over a second angle [3 between 195° and 270°. The two first drive arms 511 of the first layer 51 may be axially offset from each other by an axial distance d, and the two second drive arms 521 may be axially offset from each other by the same axial distance d, so that the first layer 51 and the second layer 52 may be axially nested. A fold 513 may be arranged to form the axial offset corresponding to the distance axial distance d in the first layer 51 and in the second layer 52. The axial distance d may be equal to the thickness of the sheet from which the first layer 51 and the second layer 52 can be made, thus allowing the first connection zone 512 and the second connection zone 522 to be on the same plane to facilitate the fixing of the web 5 on the torque input / output element 3. Advantageously, the layers 51 and 52 may be of identical geometry.

[0082] [Fig. 10] illustrates the possibility of reducing the quantity of material used for the manufacture of the web 5 in the fourth embodiment of the invention. The layer 51 which extends circumferentially over a second angle [3 between 195° and 270° can make it possible to optimize the relative position of several layers 51 in a strip of sheet metal from which they are cut in order to limit the width L of said strip of sheet metal as well as to reduce the material waste caused.

[0083] It is emphasized that all features, as they emerge for a person skilled in the art from the present description, the drawings and the attached claims, even if concretely they have only been described in relation to other determined features, both individually and in any combinations, can be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

[0084] The use of the verb “comporter”, “comprendre” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0085] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

Claims

Claims

1. Torsion damper (1) for a torque transmission device, in particular for a vehicle transmission chain, the torsion damper (1) comprising: • a torque input element (2) and a torque output element (3) movable in rotation relative to each other about an axis of rotation (X); • elastic members (4) elastically coupling in rotation the torque input element (2) to the torque output element (3); and • a web (5) configured to cooperate in rotation with the elastic members (4);characterized in that the web (5) comprises a plurality of axially stacked layers (51, 52), the plurality of layers comprising a first layer (51) comprising at least two first drive arms (511) and a second layer (52) comprising at least two second drive arms (521), the at least two first drive arms (511) and the at least two second drive arms (521) extending radially to be positioned circumferentially between two elastic members (4), the at least two first drive arms (511) being connected to the at least two second drive arms (521) by a connecting means (6).;

2. A torsion damper (1) according to claim 1, wherein the connecting means (6) is a riveting connection (61).

3. Torsion damper (1) according to claim 1, wherein the connecting means (6) is a welding connection (62), in particular a connection by electric resistance welding or by laser welding, in particular by transparency laser welding.

4. A torsion damper (1) according to any preceding claim, wherein the first layer (51) and the second layer (52) are made of steel which has undergone a hardening treatment, in particular a hardening treatment making it possible to obtain a surface hardness of 300 to 800 HV.

5. A torsion damper (1) according to any preceding claim, wherein the first layer (51) and the second layer (52) are each made from a steel sheet of constant thickness, in particular a steel sheet having a constant thickness of between 0.8 and 3 mm.

6. A torsion damper (1) according to any preceding claim, wherein the number of layers (51, 52) is between 2 and 7.

7. A torsion damper (1) according to any preceding claim, wherein the first layer (51) further comprises a first connection area (512) and the second layer (52) further comprises a second connection area (522), the first connection area (512) and the second connection area (522) being configured to be attached to the torque input element (2) or the torque output element (3).

8. A torsion damper (1) according to any preceding claim, wherein the first layer (51) and the second layer (52) are circumferentially segmented into a plurality of segments, each segment extending circumferentially over a first angle (a), in particular a first angle (a) of between 15° and 220°.

9. A torsion damper (1) according to any one of claims 1 to 7, wherein the first layer (51) and the second layer (52) extend circumferentially over a second angle (|3) of between 195° and 360°, preferably over a second angle (|3) of between 195° and 270°.

10. A torsion damper (1) according to any preceding claim, wherein the first layer (51) and the second layer (52) are flat.

11. A torsion damper (1) according to any one of claims 1 to 9, wherein the at least two first drive arms (511) are axially offset from each other by an axial distance (d), and the at least two second drive arms (521) are axially offset from each other by said axial distance (d), so that the first layer (51) and the second layer (52) are axially nested.

12. Torsion damper (1) according to claim 11 in combination with claim 5, wherein the axial distance (d) is equal to the thickness of the sheet from which the first layer (51) and the second layer (52) are made.

13. A torsion damper (1) according to any preceding claim, wherein the first layer (51) and the second layer (52) are of identical geometry.

14. Torsion damper (1) according to any one of the preceding claims, said torsion damper (1) being a double damping flywheel comprising: • a primary mass comprising the torque input element (2) in the form of a primary flywheel intended to be driven in rotation by a driving shaft; • a secondary mass comprising the disc (5) and the torque output element (3) in the form of a secondary flywheel or a hub capable of cooperating, directly or via a clutch, with a driven shaft; and • the elastic members (4), in the form of a plurality of springs elastically coupling in rotation the primary mass and the secondary mass.

15. Torque transmission device, in particular for a vehicle drive chain, comprising a torsion damper (1) according to one of the preceding claims and a clutch.

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