FR2853372A1 - Decoupling unit for driving mechanism e.g. pulley, in power transmission system, has groove treads of gear mesh encasing itself to ensure acceleration/resumption of driving mechanism while working in shearing/torsion zones - Google Patents

Abstract

The decoupling unit has complementary gear meshes (102, 112) of gear meshes (101, 103) formed on respective sides (1c, 3c) of an opposing face support. Groove treads of the gear mesh encase itself to ensure acceleration/resumption of driving mechanism while working in multiple zones of shearing/torsion. The zones are in contact with supports at the time of rotation and distributed regularly.

Description

1 2853372

  DECOUPLING ELEMENT IN ELASTIC MATERIAL AND DEVICE

  TRAINING INCLUDING THIS ELEMENT

  IN A POWER TRANSMISSION SYSTEM

  The invention relates to a decoupling element of elastic material, rubber or elastomer, for a rotary drive device, such as a pulley, roller, wheel, etc., in a power transmission system for a compressor, alternator, starter or equivalent. The invention also relates to the drive device incorporating such an element of elastic material for the transmission system.

  As illustrated by the schematic cross-sectional longitudinal and cross sectional views of FIGS. 1 and 1a, the pulleys or other rotating coupling means generally interconnect an annular rubber-shaped portion A of rectangular or profiled section between a rim. B and a central hub C. This part allows by shearing K a certain angular displacement to fulfill its transfer function, in particular frequency filter and damper. The angular phase shift is caused by the phase lag of the response (arrow R) provided to the excitation (arrow E).

  This ring A is generally fixed by overmolding or adhesion on the inner and outer faces, to cylindrical supports made of metal or plastic material, forming respectively an inner hub and an outer rim. It is also, most often, to adhere the ring on reinforcements themselves mounted in force between the rim and the hub.

  This solution, known for example from patent EP 0742377, has many drawbacks, in particular: - the adhesion requires coating and molding, which is not satisfactory in terms of cost and respect for the environment due to the use of adhesives and solvents; - The inserts, usually metal, induce a significant additional cost; the overmolding involves an additional step of necking to release the differential stresses by radial deformation, and thus also induces a cost; - The press fitting of the inserts creates stresses in the pieces; and - the system is not removable. In addition, the allowed angular clearance remains of low amplitude, which does not achieve constant stiffness couples in a sufficient range, for example at least equal to about 8 degrees. In order to overcome these disadvantages and to improve the transfer function of the elastic insert, the invention proposes to create shear / torsion zones of the elastic material.

  More specifically, the subject of the invention is a decoupling element made of deformable material, for example of elastic material, rubber or elastomer, intended to be inserted between two supports of a device for driving in rotation, and comprising a multitude of shear / torsion zones formed in contact with at least one of the supports during rotation, these zones being evenly distributed.

  According to a first embodiment, the deformable material member 20 made in a crown shape having on at least one face a meshing complementary to a meshing formed on a corresponding face of the support opposite, meshes interlocking to ensure a power transmission torque recovery by working in shear / twist lock during rotation.

  According to particular embodiments: - the meshes are in the form of grooves or crenellations, formed in recess (grooving) or protuberance (ribbing) relative to the face of the crown; - The meshes have a rectangular section or 30 variable profile along the central axis of rotation, trapezoidal or conical, for example hyperbolic, to achieve self-centering during fitting by fitting of the free crown on the support; - The ring is split to form an opening to facilitate its mounting spacing during the introduction of the hub and compression during its insertion into the rim, so as to compensate for clearances between parts; - The grooves are not constant depth, and their face has a slope inclined relative to the rest of the face of the part concerned; the meshes are made on at least one cylindrical lateral face along the axis of rotation and on the face of the support opposite, or on at least one transverse face and on the face of the support opposite; the meshes are formed on the two cylindrical or transverse lateral faces, as well as on the opposite faces of the hub and the rim of the driving device; - The meshes are made on one side of the crown, the other side of the same nature, lateral or transverse, possibly incorporating an insert; - The depths of the grooves are calculated to substantially reach a predetermined stiffness value defined by the width of the central ring not fluted.

  In a second embodiment, the decoupling element comprises a plurality of studs of deformable material 20 arranged in a star and working in shear by locking on pins regularly formed from a support of the drive device and resting on concave portions formed on the facing faces of the supports.

  According to various particular embodiments: the studs are centered on the studs, which are introduced into a central bore of each stud, and have an oblong shape in section bearing at the end on the concave portions; - The pads have a cylindrical shape having an outer face, and optionally the bore wall, regularly fluted or ribbed; the oblong studs are interposed between two studs, two studs being separated by at least one stud, preferably by two studs.

  In all its embodiments, the present invention has the following advantages: - 2853372 - pollution and implementation costs are reduced because there is no coating or adhesion; - the inserts are removed which means a gain in weight and cost; the assembly is facilitated because it frees press to achieve a fitting; - the system is removable; - The rubber parts can be manufactured in extrusion, which greatly reduces the cost.

  The present invention also relates to a device for driving an accessory in a power transmission system, comprising a limiter or torque breaker of this accessory in order to eliminate its drive in the event of a blockage, and incorporating the element made of elastic material. . According to various examples, the torque breaker is produced by a centering and clamping flange comprising balls coupled to locking rods, breakable or fractional pins regularly distributed over the flange or at least one friction elastic zone.

  The invention is detailed below in a nonlimiting manner by a description of exemplary embodiments, with reference to the appended figures which represent respectively: FIGS. 1 and 4 ibis, diagrammatic sectional views of a ring of elastic material of the state of the art (already described); FIG. 2 is an exploded view of an example of a driving device comprising complementary spline connecting pieces comprising a deformable crown decoupling element according to the invention; - Figure 2a, a sectional view of the previous assembly once mounted; - Figure 3, an exploded view of a variant with trapezoidal flutes; - Figure 4, an exploded view of a variant with a split ring and having grooves inclined slopes; - Figure 5, a sectional view of the split crown example; - Figure 6, an exploded view of an example with trapezoidal splines and formed on the transverse faces; FIGS. 7a to 7c are longitudinal and transverse sectional views with partial enlargement of an exemplary driving device comprising a resilient de-coupling element with deformable studs; - Figures 8 and 8bis, a longitudinal sectional view and a partial enlargement of an alternative embodiment of the previous example; - Figures 9 and 9a, a longitudinal sectional view and a partial enlargement of another embodiment of the example of Figures 7a to 7c; - Figures 1 Oa, 1 Ob and 1 Oc, detailed views in shear stress of pads according to the preceding three examples; and FIG. 11, a stiffness diagram for a decoupling stud according to the three preceding embodiments.

  As illustrated schematically in FIG. 2, a first example of an assembly, forming the base of a pulley, comprises a peripheral rim 1, a decoupling ring 2, and an internal hub 3. The rim and the hub are made of metal in the illustrated example and the rubber crown.

  These three pieces have rectangular grooves 100 of complementary shape. The rib-like grooves 101 of the cylindrical face 1c of the rim 1 are capable of meshing with the grooves 102 formed in a groove on the outer lateral face 2e of the crown 2, whereas the grooves 112 formed groove on the inner side face 2i of the ring 2, are adapted to mesh with the rib splines 103 of the cylindrical face 3c of the hub 3. The grooves extend in the plane of the parts which remain cylindrical according to the axis of geometry and rotation X'X.

  The central annular section, or core 22, of the ring 2 is shown in dashed lines in FIG. 2a in an example having grooves 120 for cutting with "softer" slopes than those of FIG. 2, by the presence of link. This central section 22 is width-adapted to have torsional stiffness and acceptable stresses for the application. For example, it is possible to obtain then an overall amplitude of significant angular deflection, up to degrees.

  A slight radial clearance is maintained between parts 1 and 2, and 2 and 3, due to manufacturing tolerances. If the rim and the hub support it, this game may be zero and the crown will then be mounted with slight pressure.

  The assembly is made by sliding the ring 2 between the parts 1 and 3. It is necessary to finely index the parts according to the desired game by any indexing means (optical, mechanical, etc.) known.

  The height, that is the depth, of the splines depends on the power torque to be transmitted, as well as their particular shape. This height can range, for example, from 1 mm to 5 mm.

  This central three-piece system is obtained by molding, adding light relief if necessary, or extrusion followed by bucking.

  The crown can be obtained by combining several materials, for example a material of different densities: a material for the core which is sheared and gives stiffness; a material for the external splines, with advantageously a textile reinforcement to reinforce the contact and to fight against wear; - material for internal grooves, with optional textile reinforcement.

  FIG. 3 shows a variant where the grooves 130 are of constant depth, but trapezoidal along the axis X'X.

  The section of the grooves of the crown 32 may indeed take, in addition to a rectangular shape, a trapezoidal shape or hyperbola, if one seeks to optimize the constraints in the depth of the grooves. The complementary shapes of the grooves on the base parts, rim 31 and hub 33, are also of trapezoidal or hyperbolic section.

  Advantageously, the assembly of the parts of FIG. 3 is less dependent on indexing, since the opening of the trapeziums allows an angular clearance, the small bases of the parts 31 and 33 facing the large bases of the trapeziums 130. -centrage is then done at the time of assembly.

  In this case, the molding is preferable, but the extrusion is also possible, with re-machining of the splines after cutting.

  FIG. 4 illustrates another variant of the basic assembly of FIG. 2, but in which the grooves 140 of the crown 42 and of the hub 43 are not of constant depth because they have a non-zero slope with respect to the surface. not fluted. In this variant, the rubber ring 42 is slotted to form an opening 4, at the 1o level of a groove.

  Thus, during assembly, the hub 43 spreads the crown 42 outwardly. At the end of assembly, there is no clearance between the base pieces 41 or 43 and the crown 42.

  The sectional view according to FIG. 5 shows the spreading forces (arrow F1) exerted by the hub 43 on the ring gear 42 and compensated by the compression exerted by the rim 41 on this ring gear 42 (arrows F2).

  In the case of the variant illustrated in FIG. 6, trapezoidal splines 160 are formed in groove 162 on the ring, in the plane perpendicular to the axis of rotation X'X and more precisely on the transverse faces 62t of the ring 62 The rib-shaped complementary grooves 161 and 163 are formed on the transverse faces 61t and 63t respectively of the rim 61 and the hub 63.

  According to another embodiment, an exemplary drive device comprises, with reference to the cross-sectional view of FIG. 7a, a decoupling element 2a with deformable pads 72 made of rubber. The studs are evenly distributed in a star between the walls P1 and P2 of the rim 1a.

  The studs 72 are centered on studs 73 formed on the hub 3a (with reference to the longitudinal sectional half-view of FIG. 7b), each stud 73 being introduced into a central bore 7a of each stud.

  The pads 72 have an oblong sectional shape, as shown in the enlarged view of Figure 7c. The ends 7e of the stud 72 are supported in concave portions Pc of the walls Pi 35 and P2 of the rim 1a.

  The assembly may be obtained by molding, possibly adding slight adjustment scrap, or extrusion followed by cutting.

  The dimensions of the studs can range from 8 mm in diameter 5 to 30 mm. The nipples are dimensioned according to the resistance criteria of the materials.

  In Figures 8 and 8a, corresponding to views 7a and 7c, an alternative embodiment of the previous example is illustrated. In this variant, the pads 82 have a cylindrical shape with a substantially circular cross section, and have an outer face 82e and a bore wall 8a, regularly fluted or ribbed.

  With reference to FIGS. 9 and 9bis, according to views respectively corresponding to views 8 and 8bis, another variant embodiment is illustrated. In this variant, the pads 92 of oblong shape, i identical to that of the pads of the variant illustrated by Figures 7a and 7c, are interposed between two pins 73, two successive pads being separated by two pins. The nipples are thus arranged by two to separate the studs.

  Depending on the size of the nipples and studs, as well as their shape, it is possible to provide a single stud between two studs, or more than one.

  Figures 10a, 10b and 10c illustrate the deformation of the pads according to the three preceding variants, when a torsion is imposed on the entire device in operation. The deformations of the studs 72, 82 and 92 show the effect of the shear stresses between the studs 73 and the walls P1 and P2 of the rim 1a.

  The diagram of FIG. 11 illustrates the stiffnesses K 1, K 2 and K 3 obtained by stud, respectively of the type 72, 82 and 92, of rubber of hardness 60 Shore A. The diagram bears the torque of power Cp as a function of the angle of Ad displacement. If we multiply the number of studs, the overall stiffness is multiplied by the same amount.

  It appears that a deflection angle of up to 9 degrees can be obtained with a substantially constant stiffness and a torque of up to 6 Nm for the stud embodiment variant disposed between two pins (FIGS. 9 and 9a).

  The invention is not limited to the embodiments described and shown. It is possible to use a deformable plastic material, polypropylene, polyethylene or polyamide, or a composite material of the type TPE (thermoplastic elastomer).

  Moreover, studs of cylindrical shape or of ovoid, polygonal, conical or parallelepipedal shape, possibly having grooves, can also be interposed between the studs.

  It is also possible to keep an insert, and use the grooves for the outer face where the diameter allows to accommodate more flutes.

  In addition, the pins can be formed from the rim or hub 1o, the pads can be supported on the walls of the rim and / or the hub.

  The invention is applicable to all driving devices having a filter, damping or absorber element.

  The accessories driven in rotation may be for example any motor or transmission element of a motor vehicle.

Claims (19)

  1. Decoupling element of deformable material, intended to be interposed between two supports (1, la; 3, 3a) of a rotary drive device, characterized in that it comprises a multitude of shear zones / torsion (102, 120, 130, 140, 162, 72, 82, 92) formed in contact with at least one of the supports (1, la; 2, 2a) during rotation, these areas being evenly distributed.   2. Decoupling element deformable material according to claim 1, characterized in that it is of elastic material, rubber or elastomer.   Decoupling element according to Claim 2, characterized in that it is in the form of a ring gear (2, 32, 42, 62) having on at least one face (2e, 2i, 62t) a meshing (102, 112; 120, 130, 140, 162) complementary to a meshing (101, 103, 161, 163) formed on a corresponding face (1c, 3c; 61t, 63t) of the facing support (1, 3; 33, 41, 43, 61, 63), the meshes (100) engaging to provide power transmission torque recovery by working shear / twist lock during rotation.   4. Decoupling element according to the preceding claim, 20 wherein the meshes (100) are in the form of grooves or crenellations, formed in recess or in protuberance with respect to the face (2e, 2i, 62t) of the crown.   5. Decoupling element according to the preceding claim, wherein the meshes have a variable profile section (130, 160) along the central axis of rotation (X'X), to achieve a self-centering during assembly by interlocking the free crown (32, 62) on the support.   6. decoupling element according to the preceding claim, wherein the profile of the meshes is trapezoidal or hyperbolic.   The decoupling element according to any one of claims 3 to 6, wherein the ring gear (42) has an aperture (4) to facilitate its spaced mounting upon insertion of the hub (43) and compression when inserted into the rim (41), so as to compensate for play between the parts.   The decoupling element according to any one of claims 3 to 7, wherein the grooves (140) of the hub and the crown are not of constant depth and have an inclined slope with respect to the remainder of the face. the piece (42, 43).   9. Decoupling element according to any one of claims 3 to 8, wherein the meshes are formed on at least one cylindrical side face (2e, 2i) along the axis of rotation (X'X) and on the face the support facing (1c, 3c).   10. Decoupling element according to any one of claims 3 to 8, wherein the meshes are formed on at least one transverse face (62t) of the ring (62) and on the face (61t, 63t) of the support ( 61, 63) opposite.   11. Decoupling element according to claim 9 or 10, wherein the meshes are formed on the two cylindrical lateral faces (2e, 2i) or transverse (62t) of the ring, and on the opposite faces of the hub (1c, 61t) and the rim (3c, 63t) of the drive device 15.   12. A decoupling element according to any one of claims 3 to 8, wherein the meshes are formed on one side of the crown (2), the other face of the same nature, lateral (2e, 2i) or transverse ( 62t), possibly incorporating an insert.   The decoupling element according to any one of claims 3 to 12, wherein the depths of the splines are calculated to substantially reach a predetermined stiffness value defined by the width of the undivided central ring (22) of the ring.   14. Decoupling element according to any one of claims 3 to 13, wherein the ring (2) is obtained by combining several materials or a material of different densities: - a material for the core (22) which is sheared and gives stiffness; a material for the outer splines (102), with optional textile reinforcement; - a material for the internal grooves (112), with an optional textile reinforcement.   15. Decoupling element according to claim 1 or 2, characterized in that it comprises a plurality of studs (72, 82, 92) of deformable material arranged in a star and working in shear by locking on pins (73) formed regularly from a support (la, 3a) of the driving device and resting on concave portions (Pc) formed on the faces (P1, P2) facing at least one support (1 a, 3a) .   16. Decoupling element according to the preceding claim 5, wherein the pads 72) are centered on the pins (73) introduced into a central bore (7a) of each stud, and have an oblong shape in section bearing at the end ( 7c) in concave portions (Pc) of at least one support (la, 3a).   17. Decoupling element according to claim 15, 0o characterized in that the pads (82) have a cylindrical shape having an outer face (82e), and optionally the bore wall (8a) regularly fluted or ribbed.   18. Decoupling element according to claim 15, characterized in that the studs (92) are interposed between two studs (73), two studs being separated by at least one stud, preferably by two studs.   19. Decoupling element according to the preceding claim, wherein the pads (92) are oblong.