FR3033014A1 - PULLEY DEVICE AND METHOD OF MANUFACTURING THE SAME - Google Patents

Abstract

The pulley device comprises a bearing provided with an inner ring 18, an outer ring 20 and at least one row of rolling elements 22 disposed between said rings, and a pulley 14 comprising an inner axial portion 36 mounted on said outer ring, an outer axial portion 34 and an intermediate connecting portion 38 connecting said inner and outer axial portions. The device further comprises an annular stiffening body 16 disposed radially between the outer and inner axial portions 34, 36 of the pulley and mounted radially in abutment against said portions. Said stiffening body extends axially on either side of the intermediate portion 38 connecting said pulley. Said stiffening body is delimited axially by two annular opposite side faces 16a, 16b.

Description

The present invention relates to the field of pulley devices for tensioning rollers or reels intended to cooperate with a chain or a belt, for example a motor vehicle internal combustion engine timing belt. Such rollers are generally used to permanently maintain a tension on the belt or chain in a specific range or to locally change the path taken by it.

A pulley device is provided with a bearing comprising an inner ring and an outer ring and a pulley comprising an inner axial portion attached to the outer ring, an outer axial portion adapted to cooperate with the belt or chain and a portion connecting intermediate connecting said inner and outer axial portions. Conventionally, the pulley further comprises a plurality of stiffening ribs extending radially between the inner and outer axial portions and connecting to the intermediate portion. The stiffening ribs are spaced relative to each other in the circumferential direction. The ribs are provided to limit the deformations of the outer axial portion of the pulley under the effect of the forces exerted by the belt or the chain. Generally, the pulley is made of plastic overmolded on the outer ring of the bearing.

In operation, during the rotation of the pulley, the stiffening ribs cause undesired noise generation. To remedy this drawback, US Pat. No. 8,617,016 recommends providing an irregular circumferential spacing of the stiffening ribs of the pulley made of plastic material.

However, even with such a solution, the noise generation can remain significant for example at a high speed of rotation of the pulley. Moreover, with this type of design, bosses tend to form on the outer surface of the outer axial portion of the pulley during manufacture of said pulley. The present invention aims to remedy these disadvantages. More particularly, the present invention aims to provide a pulley device for operation with limited noise generation and providing a contact surface to the associated belt or chain having good circularity. In one embodiment, the pulley device comprises a bearing provided with an inner ring, an outer ring and at least one row of rolling elements disposed between said rings, and a pulley comprising an inner axial portion. mounted on said outer ring, an outer axial portion and an intermediate connecting portion connecting said inner and outer axial portions.

The device further comprises an annular stiffening body arranged radially between the outer and inner axial portions of the pulley and mounted radially bearing against said portions. Said stiffening body extends axially on either side of the intermediate connecting portion of said pulley. Said stiffening body is delimited axially by two opposite annular side faces. The disposition of the annular stiffening body between the inner and outer axial portions of the pulley allows a uniform distribution in the circumferential direction of the radial forces exerted by the belt or chain associated with the device. The opposite lateral faces of annular shape axially delimiting the stiffening body also make it possible to avoid the generation of noise during the rotation of the pulley. Furthermore, since the pulley is devoid of stiffening ribs extending radially between the inner and outer axial portions, the risk of deformation of the outer surface of the outer axial portion is limited when said pulley is obtained by molding. Indeed, after molding, the cooling of the pulley is uniform. The outer surface of the pulley thus exhibits good circularity even in a molding process of a synthetic material. Preferably, the annular side faces of the stiffening body are smooth. By "smooth" is meant a face devoid of projections, nubs, asperities, ribs, etc. or grooves or recesses, etc. This design further reduces the risk of noise generation during rotation of the pulley. In one embodiment, the intermediate connecting portion 10 of the pulley is disposed in a median radial plane of the bearing. This promotes a good recovery of the forces exerted by the belt or associated chain. Preferably, the pulley is made of synthetic material. In one embodiment, the stiffening body 15 comprises at least two parts arranged axially on either side of the intermediate connecting portion of the pulley. The stiffening body may be made of synthetic material, in particular of rigid synthetic material. Advantageously, the stiffening body is overmoulded on the pulley. In this case, the inner axial portion and / or the outer axial portion of the pulley may comprise notches and the stiffening body may comprise complementary ribs extending inside said notches. Alternatively or in combination, at least one through recess may be formed in the thickness of the intermediate connecting portion of the pulley and within which extends a stud of the stiffening body. The invention also relates to a method of manufacturing a pulley device of the type provided with a bearing and a pulley comprising an inner axial portion, an outer axial portion and an intermediate connecting portion connecting said inner axial portions and outer, in which the inner axial portion of the pulley is fixed on an outer ring of the bearing. An annular stiffening body delimited axially by two opposite annular lateral faces is fixed on the pulley. Said stiffening body 3033014 4 is mounted radially between the inner and outer axial portions of said pulley bearing against said portions. Said stiffening body extends axially on either side of the intermediate connecting portion of said pulley.

In a preferred embodiment, the pulley is overmolded on the outer ring of the bearing during a first step, and the stiffening body is overmoulded on the pulley during a second successive step. The present invention will be better understood on studying the detailed description of embodiments taken by way of non-limiting examples and illustrated by the appended drawings, in which: FIG. 1 is an axial sectional view of a pulley device according to a first embodiment of the invention, - Figure 2 is a sectional view along the axis II-II of Figure 1 - Figure 3 is a perspective view of the pulley device of the FIG. 4 is an axial sectional view of a pulley device according to a second exemplary embodiment of the invention, FIG. 5 is a sectional view along the axis VV of FIG. 4, and FIG. 6 is a perspective view of the pulley device of FIG. 4. In FIGS. 1 to 3, a pulley device, referenced as a whole, having an axis 10a, comprises a bearing 12, a pulley 14 fixed on the bearing and a body 16 stiffening reported on the pulley. As will be described in more detail below, the stiffening body 16 is a separate component of the pulley 14 which is attached thereto.

The bearing 12, of axis 10a, comprises an inner ring 18, an outer ring 20 and two rows of rolling elements 22 and 24, made here in the form of balls, arranged radially between the raceways formed on said rings. The bearing 12 also comprises cages 26, 28 respectively provided for the maintenance of the regular circumferential spacing of each row of rolling elements 22, 24. The bearing 12 further comprises axially on each side a seal 30 , 32 annular fixed to the outer ring 20 to close the radial space existing between the rings and within which are housed the rolling elements 22, 24 and associated cages 26, 28. The inner rings 18 and outer 20 of the bearing are concentric. In the exemplary embodiment illustrated, the rings are massive. The term "solid ring" means a ring whose shape is obtained by machining with removal of chips (turning, grinding) from tubes, bars, forged blanks and / or rolled. The outer ring 20 comprises an axial cylindrical outer surface 20a, a cylindrical bore 20b and two opposite radial front surfaces 20c, 20d axially delimiting said bore and the outer surface. The outer ring 20 further comprises two raceways (not referenced) formed on the bore 20b and having in cross section a concave internal profile adapted to the rolling elements 22 and 24, said raceways 20 being directed radially inwards. The outer ring 14 also comprises two annular (unreferenced) grooves formed on the bore 20b for fixing the seals 30, 32. Similarly, the inner ring 18 comprises a cylindrical bore 25, a cylindrical axial outer surface , two opposed radial front surfaces axially delimiting said bore and the outer surface, and two raceways formed on the outer surface and having in cross section a concave internal profile adapted to the rolling elements 22 and 24, said raceways being directed radially. outwards. In the exemplary embodiment illustrated, the inner ring 18 protrudes axially from both sides relative to the outer ring 20. Alternatively, it is possible to provide an inner ring 18 comprising coplanar front surfaces with the surfaces The pulley 14 comprises an annular outer axial portion 34 provided with an axial cylindrical outer surface 34a intended to cooperate with a belt or a chain (not shown), an annular inner axial portion 36 and a portion annular radial intermediate 38 connecting said portions. The pulley 14 is attached to the bearing 12 via the inner axial portion 36. The outer 34 and inner 36 axial portions are coaxial with the axis 10a. The outer axial 34 and inner 36 portions are spaced from each other in the radial direction. The outer axial portion 34 radially surrounds the inner axial portion 36. The intermediate connecting portion 38 extends radially outwardly from the inner axial portion 36 and connects to the outer axial portion 34. The intermediate portion 38 connection is arranged in the radial radial plane of the bearing 12. This promotes a good recovery by the bearing 12 of the forces exerted by the belt or the chain on the pulley 14. In the illustrated embodiment, the pulley 14 is made of one piece.

The inner axial portion 36 of the pulley comprises a cylindrical bore 36a mounted radially in contact with the outer surface 20a of the outer race of the bearing. Annular attachment ribs 40 to 44 are formed in the bore 36a and extend radially within annular grooves (not referenced) formed on the outer surface 20a of the outer race of the bearing. The ribs 40 to 44 are in complementary form with the grooves of the outer ring 20. In the illustrated embodiment, the pulley 14 is made by overmolding on the outer ring 20 of a synthetic material, for example a polyamide . Alternatively, it could be possible to mold the pulley 14, and then to fix it on the outer ring 20 by any other appropriate means, for example by gluing. The stiffening body 16, of annular shape, is arranged radially between the outer axial portions 34 and inner 36 of the pulley. The body 16 comes radially in abutment against said portions. The body 16 is mounted radially in abutment against an axial cylindrical outer surface 36b of the inner axial portion 36. The body 16 is mounted radially in abutment against a cylindrical bore 34b of the outer axial portion 34. The stiffening body 16 extends axially on either side of the intermediate portion 38 connecting the pulley. The stiffening body 16 is disposed axially on either side of the intermediate portion 38. The body 16 remains axially recessed from the end faces of the end of the outer axial portion 34 of the pulley. The body 16 is located radially inside each radial space defined between the outer axial 34 and inner portions 36 of the pulley, said space being located axially on each side of the intermediate portion 38 of said pulley connecting.

The stiffening body 16 is defined axially by two opposite lateral annular faces 16a, 16b. The annular faces 16a, 16b form the front or end surfaces of the body 16. The faces 16a, 16b of the stiffening body are oriented axially on the outside of the device. The faces 16a, 16b are disposed axially on either side of the intermediate portion 38 connecting the pulley. Each face 16a, 16b is continuous in the circumferential direction. Each face 16a, 16b extends between the inner axial portions 36 and outer 34 of the pulley being connected to said portions. Each face 16a, 16b extends radially outwardly the inner axial portion 36 of the pulley and connects to the outer axial portion 34. In the exemplary embodiment shown, each face 16a, 16b extends from the outer surface 36b of inner axial portion to the bore 34b outer axial portion of the pulley. In the exemplary embodiment illustrated, each face 16a, 16b has a frustoconical shape flaring outwardly. Alternatively, the faces 16a, 16b of the body could extend radially purely. The stiffening body 16 is made of a synthetic material, for example a rigid synthetic material such as polyamide or foam, or a flexible synthetic material such as an elastomer or a rubber or an elastomeric thermoplastic. The stiffening body 16 is fixed on the pulley 14. Preferably, the body 16 is overmolded onto the pulley 14. Alternatively, it may be possible to provide the attachment of the body 16 to the pulley 14 by any other appropriate means, for example example by gluing. In the exemplary embodiment illustrated, the stiffening body 16 is made of two distinct parts 50, 52 which are arranged axially on either side of the intermediate portion 38 for connecting the pulley. The two parts 50, 52 of the body are symmetrical by considering the radial radial plane of the bearing 12 passing through the intermediate portion 38 connecting the pulley. Each portion 50, 52 of the body comprises one of the faces 16a, 16b. To manufacture the device 10, the procedure is as follows. In a first step, the pulley 14 is overmolded on the outer ring 20 of the bearing. This results in excellent adhesion between these two parts, in particular at the grooves of the outer ring 20 into which the molten synthetic material penetrates to form the ribs 40 to 44 in the bore 20 of the pulley by complementary shape. Then, during a second successive step, the stiffening body 16 is overmoulded on the pulley 14. The two parts 50, 52 of said body are obtained in a single operation. In another embodiment of the manufacturing method, it could be possible to provide the attachment of the stiffening body 16 to the pulley 14, for example by overmolding or gluing, before the step of fixing said pulley on the 12. In this case, the pulley 14 can be made by molding a synthetic material, or alternatively be made of another material, for example sheet metal, and then be fastened to the bearing 12 by any appropriate means. In operation, during the rotation of the pulley 14, the faces 16a, 16b of the stiffening body do not participate in the noise generation. Each annular face 16a, 16b of said body forms a continuous surface in the circumferential direction and extending between the inner and outer axial portions 36 of the pulley. Pulley 14 is free of stiffening ribs extending between these circumferentially spaced, outwardly facing axial portions of the device which are noise generating. Furthermore, the ring-shaped stiffening body 16 makes it possible to obtain a device which, by design, has good resistance to radial forces. In order to further limit the generation of noise by the stiffening body 16, the body faces 16a, 16b are preferably smooth. The exemplary embodiment illustrated in FIGS. 4 to 6, in which the identical elements bear the same references, differs from the first example described only in that a plurality of notches 54, 56 are respectively formed on the outer surface 36b of FIG. the inner axial portion and in the bore 34b of the outer axial portion of said pulley. The notches 54 extend radially inwardly from the outer surface 36b of the inner axial portion 36. The notches 54 extend axially along the outer surface 36b. The notches 54 are here four in number and evenly spaced in the circumferential direction. The notches 56 extend radially outwardly from the bore 34b of the outer axial portion 34 of the pulley. The notches 56 extend axially along the bore 34b. The notches 56 are here also four in number and regularly spaced in the circumferential direction. The notches 54, 56 extend axially on either side of the intermediate portion 38 connecting the pulley. Fastening ribs (not referenced) are formed in the bore of the stiffening body 16 and on the outer surface 30 of said body and extend respectively inside the notches 54, 56 of the pulley. The hooking ribs extend over the two parts 50, 52 of the body 16. The ribs are in complementary form with the notches 54, 56. These ribs are formed during overmoulding of the stiffening body 16 on the pulley 14. This promotes the attachment of the body 16 to the pulley 14. For this purpose, it may still be possible to provide a plurality of through recesses formed in the thickness of the intermediate portion 38 connecting the pulley. Thus, the stiffening body 16 would comprise a plurality of studs axially extending each through one of these through recesses. In this case, the two parts 50, 52 of the body would be connected via the axial pads. The invention has been illustrated on the basis of a pulley device comprising a bearing equipped with several rows of balls. Alternatively, it is also possible to provide a device provided with a bearing comprising rolling elements which are not balls, and / or a single row of rolling elements. Thanks to the invention, a pulley device is provided which makes it possible to operate with a limited noise generation in view of the annular shape of the end faces of the end of the stiffening body. Furthermore, the annular stiffening body provides a device having good resistance to the forces exerted by the associated belt or chain and limiting the risk of buckling. In addition, the outer surface of the pulley has a satisfactory circularity even when the pulley is obtained by molding a synthetic material.

Claims (10)

REVENDICATIONS1. A pulley device comprising a bearing provided with an inner ring (18), an outer ring (20) and at least one row of rolling elements (22) disposed between said rings, and a pulley (14) comprising an inner axial portion (36) mounted on said outer ring, an outer axial portion (34) and an intermediate connecting portion (38) connecting said inner and outer axial portions, characterized in that the device further comprises a body (16). ) annular stiffening disposed radially between the outer and inner axial portions (34, 36) of the pulley and mounted radially bearing against said portions, said stiffening body extending axially on either side of the intermediate portion (38). ) of said pulley, said stiffening body being defined axially by two opposite annular side faces (16a, 16b). 2. Device according to claim 1, wherein the annular side faces (16a, 16b) of the stiffening body are smooth. 3. Device according to claim 1 or 2, wherein the intermediate portion (38) connecting the pulley is disposed in a radial radial plane of the bearing. 4. Device according to any one of the preceding claims, wherein the pulley (14) is made of synthetic material. 5. Device according to any one of the preceding claims, wherein the body (16) of stiffening comprises at least two parts (50, 52) arranged axially on either side of the intermediate portion (38) of the connection of the pulley. 6. Device according to any one of the preceding claims, wherein the body (16) stiffening is overmolded on the pulley (14). 7. Device according to claim 6, wherein the axial portion (36) and / or the outer axial portion (34) of the pulley comprise notches (54, 56) and the body (16) of 3033014 12 stiffening comprises complementary ribs extending inside said notches. 8. Device according to claim 6 or 7, wherein at least one through recess is formed in the thickness of the intermediate portion (38) connecting the pulley and within which extends a stud of the body of stiffening. 9. A method of manufacturing a pulley device of the type provided with a bearing and a pulley comprising an inner axial portion, an outer axial portion and an intermediate connecting portion connecting said inner and outer axial portions, wherein the inner axial portion of the pulley is fixed on an outer ring of the bearing, characterized in that an annular stiffening body defined axially by two opposite annular side faces is fixed on the pulley, said stiffening body being mounted radially between the inner and outer axial portions of said pulley bearing against said portions, said stiffening body extending axially on either side of the intermediate connecting portion of said pulley. 10. The method of claim 9, wherein the pulley is overmolded on the outer race of the bearing during a first step, and the stiffening body is overmolded on the pulley in a second successive step.