WO2018001795A1

WO2018001795A1 - Torque limiting mechanism

Info

Publication number: WO2018001795A1
Application number: PCT/EP2017/065103
Authority: WO
Inventors: Olivier Marechal
Original assignee: Valeo Embrayages
Priority date: 2016-06-29
Filing date: 2017-06-20
Publication date: 2018-01-04
Also published as: CN109416083A; FR3053420B1; FR3053420A1; CN109416083B

Abstract

The invention relates to a torque limiting mechanism (10) which includes a reaction plate (14) and a bearing plate (16) forming two separate parts secured to one another, a pressure plate (36) arranged between the bearing plate (16) and the reaction plate (14), and axially movable relative to the reaction plate (14), a friction disc (48) provided with friction linings (50) arranged between the pressure plate (36) and the reaction plate (14), at least one resilient member (44) engaging with the bearing plate (16) and capable of permanently returning the pressure plate (36) towards the reaction plate (14), and a central attachment portion (22) including at least one hole (24) parallel to the axis of rotation (100) for securing the torque limiting mechanism (10) to a primary shaft, the central attachment portion (22) being formed integral with the reaction plate (14) or with the bearing plate (16).

Description

TORQUE LIMITING MECHANISM

TECHNICAL FIELD OF THE INVENTION

The invention relates to a torque limiting mechanism for insertion into a kinematic propulsion system of a vehicle.

STATE OF THE PRIOR ART

In US 7,766,752 is described a torque fluctuation filtration mechanism comprising a flywheel fixed to the motor shaft driving a torque limiter associated with a damping device. The torque limiter comprises a reaction plate, a support plate, a pressure plate disposed between the support plate and the reaction plate, and movable axially relative to the reaction plate, a friction disk comprising linings. friction device disposed between the pressure plate and the reaction plate, and an elastic member bearing on the support plate and able to permanently return the pressure plate to the reaction plate in an axial direction of support placing at least some of the friction liners in contact with the pressure plate and at least some of the friction liners in contact with the reaction plate. The friction disk is attached to an input member of the damping mechanism further comprising an output member adapted to oscillate about the axis of revolution relative to the input member, and elastic elements working in function of the oscillations of the output member with respect to the input member. The reaction plate and the support plate of the torque limiter are fixed to the flywheel by screws distributed around the periphery of the flywheel. The mechanism thus described comprises a large number of parts, which can be assembled only after mounting the flywheel to the motor shaft.

SUMMARY OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art and in particular to provide a torque limiter having a limited number of parts. To do this is proposed, according to a first aspect of the invention, a torque limiting mechanism, adapted to rotate about an axis of revolution, comprising: a primary subassembly comprising a reaction plate and a plateau of support constituting two separate parts fixed to one another, a pressure plate disposed between the support plate and the reaction plate, and movable axially relative to the reaction plate, a secondary subassembly comprising a friction disk provided with friction linings arranged between the pressure plate and the reaction plate, and at least one resilient member bearing on the support plate and able to permanently reminder the pressure plate towards the reaction plate by putting the pressure plate and the reaction plate in contact with the friction linings,

According to the invention the mechanism comprises a sheet metal part constituting a first plate among the reaction plate and the support plate, the sheet metal part comprising a central fixing part comprising at least one hole parallel to the axis. revolution for fixing the torque limiting mechanism to a primary shaft, preferably a crankshaft, a massive one-piece piece constituting a massive flywheel and a second plate among the reaction plate and the support plate.

The central portion is located radially inside the friction linings. The link function of the torque limiter to the input shaft is thus made directly by one of the component parts of the torque limiter, and not via an additional piece. The central fastening portion, constituted by the sheet metal part, has a bulk and a low mass, which allows to keep a small footprint to the casing of the mechanism. Advantageously, the sheet metal part has a friction face facing the friction linings.

Advantageously, the sheet metal part is direct support on the friction disk lining. Preferably, the secondary subassembly comprises a friction disc interposed axially between the support plate and the reaction plate.

According to one embodiment, the sheet metal part is flexible and is shaped to allow an axial displacement of the central fixing portion relative to the friction face. Preferably, the friction face of the sheet metal part is offset axially relative to the central fastening portion. This axial offset of the central part makes it possible, if necessary, to house elements of the mechanism. In addition, this configuration allows, if necessary, a controlled and limited flexing of the sheet metal part, decoupling its central portion from its peripheral portion comprising the friction face.

Advantageously, the sheet metal part has openings arranged radially on the central fixing part. Preferably, the openings are angularly distributed around the axis of revolution. In this way, the jerks in axial translation and in nutation transmitted by the primary shaft are absorbed and are not retransmitted to the friction disc.

[0013] Preferably, the solid piece constitutes the support plate. Indeed, the solid monobloc piece is particularly suitable for the integration of ancillary functions assigned to the support plate, as discussed below.

Advantageously, the support plate and the reaction plate are fixed to one another by peripheral screws parallel to the axis of revolution. Preferably, the heads of the screws are located on the side of the solid piece opposite to the sheet metal part, which facilitates assembly. According to one embodiment, the primary subassembly further comprises a starter gear ring, preferably constituting a third piece distinct from the support plate and the reaction plate.

According to one embodiment, the primary subassembly further comprises at least one guide face in translation and rotational locking of the pressure plate relative to the support plate, the guide face being constituted by the reaction plate, the support plate and / or a guide piece reported. The pressure plate and the elastic means thus rotate with the support plate and the reaction plate. According to one embodiment, the pressure plate comprises at least one lug extending radially outwardly, the support plate having at least one notch shaped to allow axial insertion of the lug into the notch . The side walls of the housing may constitute the guide face or faces in translation and rotational locking of the pressure plate relative to the reaction plate. Alternatively, it can be provided that the pressure plate comprises a housing offset orthoradially with respect to the notch, to allow axial insertion of the tab into the notch and then insertion of the tab into the housing by rotation about the axis of revolution. This provides a bayonet attachment between the pressure plate and the support plate. Axial guidance and locking in rotation of the pressure plate relative to the support plate are then preferably obtained by rods inserted axially through the pressure plate and the support plate. According to this embodiment, the support plate forms with the pressure plate and the elastic member a subassembly that can be preassembled before assembling the friction disk and the reaction plate.

The support plate may be annular and have an inner diameter greater than the outer diameter of the central fixing portion.

The friction disc has an annular fixing portion located radially inside the friction linings. The friction disc is preferably axially flexible, so as to allow a slight axial displacement between the friction linings and the annular fixing portion.

According to a particularly advantageous embodiment, the friction disc is attached to an input member of a torque fluctuation filtering mechanism further comprising an output member adapted to oscillate about the axis of revolution. relative to the input member, and resilient elements operating according oscillations of the output member relative to the input member. The elastic members are preferably springs, for example straight or curved coil springs. The output member is preferably secured to a splined hub rotatably connected to a secondary shaft. The torque fluctuation filtration mechanism can in particular be of the type comprising two guide washers positioned axially on either side of a web. The input member may be one of the guide washers, the output member being in this case the veil. Alternatively, the input member is constituted by the web and the output member by one of the guide washers. The torque fluctuation filter mechanism may incorporate a damping mechanism provided with friction elements for dissipating heat of kinetic energy during oscillations of the output member with respect to the input member. Preferably, the output member of the torque fluctuation filtration mechanism is housed at least partially in an open cavity delimited by the support plate and the reaction plate.

According to another embodiment, the friction disk is integral with a splined hub rotatably connected to a secondary shaft.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent on reading the description which follows, with reference to the accompanying figures, which illustrate: Figure 1, an axial section of a torque limiting mechanism according to a first embodiment embodiment of the invention; Figure 2, an exploded view of the cutting limiter mechanism according to the first embodiment of the invention; Figure 3, an axial section of a torque limiting mechanism according to a second embodiment of the invention; Figure 4, an exploded view of the cutting limiter mechanism according to the second embodiment of the invention; - Figure 5, an axial section of a torque limiting mechanism according to a third embodiment of the invention; Figure 6, an exploded view of the cutting limiter mechanism according to the third embodiment of the invention; Figure 7, a view of an alternative embodiment of a sheet metal part of the torque limiting mechanism of Figure 1; FIG. 8 is a sectional view of another variant embodiment of the torque limiting mechanism of FIG. 1.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED DESCRIPTION OF EMBODIMENTS

Figures 1 and 2 is illustrated a torque limiting mechanism 10, rotatable about an axis of revolution 100. This mechanism comprises a primary subassembly 12 consisting essentially of a reaction plate 14, d a support plate 16 and a starter ring 18, secured by screws 20 parallel to the axis of revolution 100. The reaction plate 14 is constituted by a stamped sheet, and has a friction face 15 rotated axially towards the support plate 16, a central portion 22 axially offset relative to the friction face 15 and a frustoconical transition portion 23 between the central portion 22 and the friction face 15. The central portion 22 is provided with holes axial 24 arranged in a circle and allowing the insertion of fastening screws 26 to a motor primary shaft, for example a crankshaft. The axial offset of the central portion 22 makes it possible to accommodate these fixing screws 26. A reinforcing washer 28 may be provided to interpose between the heads of the fixing screws 26 and the central portion 22 of the reaction plate 14, in order to distribute the tightening constraints. The support plate 16 incorporates an annular solid flywheel 30, and has a radial planar bearing wall 32 extending from the flywheel radially inwards, having a bearing face 34 rotated axially to the reaction plate 14. The support plate 16 has an inside diameter greater than the outside diameter of the central fixing portion 22. The friction face 15 of the reaction plate 14 is preferably located opposite the face of the reaction plate 14. support 34.

A pressure plate 36 is disposed between the support plate 16 and the reaction plate 14. The pressure plate 36 is annular and has tabs 38 projecting radially outwardly, which are inserted into notches 40 formed in the support plate 16. The side walls 42 of the notches provide a guide of the pressure plate 36 relative to the support plate 16 parallel to the axis of revolution 100 and a locking of the pressure plate 36 relative to the support plate 16 rotated about the axis of revolution 100. An elastic member, here constituted by a Belleville washer 44, is disposed between the support plate 16 and the pressure plate 36. The washer Belleville 44 is supported on the support surface 34 of the support plate 16 and permanently urges the pressure plate 36 towards the reaction plate 14. The forces of the Belleville washer 44 are directly taken up by the support plate 16 . [0026] The reaction plate 14 is a flexible sheet metal part, shaped so as to allow an axial displacement of the central fixing portion 22 relative to the friction face 15. The axial stiffness of the flexible sheet is between 1000 and 2000N / mm.

The torque limiter mechanism 10 further comprises a secondary subassembly 46 comprising a friction disk 48 constituted by an annular plate supporting friction linings 50 disposed between the pressure plate 36 and the friction face 15 of the plate In a conventional manner, the pressure plate 36, which is mobile in translation parallel to the axis of revolution 100 and is biased by the Belleville washer 44, pinches the friction linings 50, 51, putting the friction linings 50 into position. contact with the pressure plate 36 and the friction liners 51 in contact with the friction face of the reaction plate 14. The pressure contact is controlled and function of the crushing of the Belleville washer 44, and defines a torque threshold below which the rotation of the primary 12 is integrally transmitted to the friction disc 48, and beyond which the rotation of the primary 12 n is more integrally transmitted to the friction disc 48. The friction disc 48 has at its inner periphery fixing holes which allow, in this embodiment, to fix the friction disk 48 to a first guide ring 54 constituting an input member of a torque fluctuation filtering mechanism 56. The first guide ring 54 is fixed to a second guide ring 58 by spacers not visible in the sectional plane of FIG. two guide rings 54, 58 are spaced axially from each other, and provided with openings for accommodating and guiding coil springs 60. The torque fluctuation filtering mechanism 56 c it furthermore comprises an outlet member 62 constituted by a web housed between the two guide washers 54, 58. The coil springs 60 come to bear orthoradially on the web 62 and on the guide washers 54, 58, and work when the sail 62 oscillates about the axis of revolution 100 relative to the guide washers 54, 58. A friction pad 64, integral with the web 62, rubs against a wall of the second guide ring 58, to dissipate the energy during oscillations. The web 62 is mounted on a splined hub 66, so as to be secured at least in rotation about the axis of revolution 100, the splined hub 66 being intended to be mounted on an output shaft.

The friction disk 48 and at least a portion of the torque fluctuation filter mechanism 56 are housed in a cavity 68 defined radially and axially by the support plate 16 and the reaction plate 14, in particular by the recess of the sheet formed by the central portion 22 and the transition portion 23, so that the torque limiting mechanism 10 has excellent axial compactness.

The assembly of the torque limiter mechanism 10 according to this first embodiment can be achieved in the following manner. The friction disc 48 is riveted to the first guide ring 54 of the torque fluctuation filtering mechanism 56 and forms therewith a coherent subassembly, which is inserted with the Belleville washer 44 and the pressure plate 36 inside the support plate 16. The reaction plate 14 and the starter ring 18 are threaded onto an end portion of a primary shaft and the reaction plate 14 is fixed to the primary shaft by means of the fixing screws 26. Finally, the support plate 16 is fixed to the reaction plate 14 and to the starter ring 18 by means of the screws 20.

Figures 3 and 4 is illustrated a torque limiting mechanism 10 according to a second embodiment of the invention, which differs from the previous essentially by the connection between the pressure plate 36 and the support plate 16. The pressure plate 36 is provided with tabs 38 protruding radially and on which are formed notches 70. The support plate 16 has notches 40 open axially and giving access to housing 72 offset orthoradially with respect to the notches 40, for allow, during assembly, an axial insertion of the tabs 38 in the notches 40 and an insertion of the tabs 38 in the housing 72 by rotation of a few degrees around the axis of revolution 100. The resulting movement is similar to a bayonet attachment. Once the tabs 38 in place in the housings 72, pins 74 are inserted into holes 76 provided for this purpose in the support plate 16, and laterally engage with the notches 70 of the tabs 38. The pins 74 ensure the guide in translation and the rotational connection of the pressure plate 36 relative to the support plate 16. It is thus possible to pre-assemble the support plate 16, the Belleville washer 44 and the pressure plate 36, to form a a coherent subset that is then assembled to the other subsets of the mechanism 10.

It is also possible to provide a complete assembly including the primary subassembly 12 and the secondary subassembly 46 for mounting on the crankshaft of a vehicle, by providing lights in the friction disc 48.

The torque limiter mechanism illustrated in FIGS. 5 and 6 differs from the embodiment of FIGS. 1 and 2 in the absence of a torque fluctuation filtration mechanism, the friction disk 48 being directly fixed here by rivets 82, to a splined hub 66 intended to be secured to a shaft end. The sheet constituting the reaction plate 14 is here thicker than in the mode of embodiment of Figures 1 and 2, making the reinforcement washer useless. In this third embodiment, the reaction plate 14 is rigid.

In Figure 7 has been illustrated an alternative embodiment of the embodiment of Figures 1 and 2, wherein the reaction plate 14 has an increased axial flexibility. The reaction plate 14 is constituted by a stamped sheet metal, and has a friction face turned axially towards the support plate, a central portion 22 axially offset relative to the friction face and a frustoconical transition portion 23 between the part central 22 and the friction face. The sheet metal part is perforated by openings 84 arranged radially on the central portion 22 of the reaction plate 14 to limit the mass and increase flexibility. As illustrated in FIG. 7, the reaction plate 14 has six openings 84 distributed angularly about the axis of revolution 100. The reaction plate 14 is here shaped so as to allow axial displacement of the central fixing portion 22 by compared to the friction face. The axial stiffness of the flexible sheet is of the order of 1000 N / mm, preferably between 800 and 1200 N / mm. The openings 84 are distinct from the fixing holes 24.

In Figure 8 has been illustrated another variant for screwing screws 20 in the same direction as the screws 26. To this end, the nuts 86 are welded to the starter ring 18, and the screws are screwed on. screw 20 in these nuts. Opening holes are arranged on the outer periphery of the support plate 16 allowing the passage of the screws 20. In this variant, the assembly of the torque limiting mechanism is simplified.

Naturally, the examples shown in the figures and discussed above are given for illustrative and not limiting. It is explicitly provided that the various illustrated embodiments can be combined with one another to propose others. For example, the support plate of the embodiment illustrated in FIGS. 5 and 6 is here substantially identical to the support plate of the embodiment of FIGS. 1 and 2, but a bayonet connection can alternatively be provided between the support plate and the pressure plate, of the type described in connection with the embodiment of Figures 3 and 4. It is emphasized that all the features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if concretely they have been described in relation to other particular characteristics, both individually and in any combination, may be combined with other characteristics or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances do not render such characteristics or groups of features impossible or meaningless combinations.

Claims

Torque limiting mechanism (10), rotatable about an axis of revolution (100), comprising:

a primary subassembly (12) comprising a reaction plate (14) and a support plate (16) constituting two separate parts fixed to one another,

a pressure plate (36) disposed between the support plate (16) and the reaction plate (14), and movable axially with respect to the reaction plate (14),

a secondary subassembly (46) having a friction disk (48) provided with friction liners (50,51) disposed between the pressure plate (36) and the reaction plate (14),

at least one elastic member (44) bearing on the support plate (16) and able to permanently return the pressure plate (36) to the reaction plate (14) by putting the pressure plate (36) and the reaction plate (14) in contact with the friction liners (50, 51),

characterized in that it comprises

a sheet metal part constituting a first plate among the reaction plate (14) and the support plate (16), the sheet metal part comprising a central fixing part (22) comprising at least one hole (24) parallel to the axis of revolution (100) for fixing the torque limiting mechanism (10) to a primary shaft, preferably a crankshaft, a solid one-piece component constituting a solid flywheel (30) and a second plate among the reaction plate (14) and the support plate (16).

Torque limiting mechanism (10) according to claim 1, characterized in that the sheet metal part has a friction face (15) facing the friction linings (50, 51), said sheet metal part being flexible and shaped so to allow an axial displacement of the central fixing portion (22) relative to the friction face (15).

3. Torque limiting mechanism (10) according to the preceding claim, characterized in that the sheet metal part has openings (84) arranged radially on the central portion (22) of attachment.

4. torque limiting mechanism (10) according to any one of claims 2 or 3, characterized in that the friction face (15) of the sheet metal part facing the friction liners (50, 51) is offset axially relative to the central fixing portion (22).

5. Torque limiting mechanism (10) according to any one of the preceding claims, characterized in that the massive piece comprises the support plate (16).

Torque limiting mechanism (10) according to one of the preceding claims, characterized in that the support plate (16) and the reaction plate (14) are fastened to one another by means of screws peripherals (20), parallel to the axis of revolution (100).

Torque limiting mechanism (10) according to any one of the preceding claims, characterized in that the primary subassembly (12) further comprises a starter gear ring (18), preferably constituting a third separate part of the support plate (16) and the reaction plate (14).

8. Torque limiting mechanism (10) according to any one of the preceding claims, characterized in that the primary subassembly (12) further comprises at least one face (42) for translational guiding and rotational locking of the pressure plate relative to the support plate, the guide face being formed by the reaction plate (14), the support plate (16) and / or a guide piece (74) reported. Torque limiting mechanism (10) according to any one of the preceding claims, characterized in that the pressure plate (36) comprises at least one lug (38) extending radially outwards, the support plate ( 16) having at least one notch (40) shaped to allow axial insertion of the tab (38) in the notch (40).

Torque limiting mechanism (10) according to claim 9, characterized in that the pressure plate (36) comprises a housing (42) offset orthoradially with respect to the notch (40), to allow axial insertion of the tab into the notch (40) then an insertion of the tab (38) in the housing (42) by rotation about the axis of revolution (100).

A torque limiting mechanism (10) as claimed in any one of the preceding claims, characterized in that the friction disc (48) is attached to an input member (54) of a torque fluctuation filtering mechanism (56). ) further comprising an output member (62) adapted to oscillate about the axis of revolution (100) with respect to the input member (54), and resilient members (60) operating in accordance with the oscillations of the output member (62) with respect to the input member (54).

Torque limiting mechanism according to claim 11, characterized in that the output member (62) of the torque fluctuation filtering mechanism (56) is housed at least partially in an open cavity (68) delimited by the support plate. (16) and the reaction plate (14).

Torque limiting mechanism according to any one of claims 1 to 10, characterized in that the friction disk (48) is integral with a splined hub (66) rotatably connected to a secondary shaft.