WO2011098125A1

WO2011098125A1 - Pulley for tensioning idler or runner roller.

Info

Publication number: WO2011098125A1
Application number: PCT/EP2010/051687
Authority: WO
Inventors: Jacques Charpentier; Yves-André LIVERATO; Eric Robert
Original assignee: Aktiebolaget Skf
Priority date: 2010-02-11
Filing date: 2010-02-11
Publication date: 2011-08-18
Also published as: DE112010005252T5; DE112010005252B4

Abstract

The pulley comprises an inner portion (42) mounted on a bearing and an outer portion (42) having a continuous outer surface (40a) in contact with a belt or a chain. The inner and outer portions (42, 40) are made in one piece. The pulley further comprises stiffening means (46) of the outer portion coming into contact with a bore (40b) of said portion.

Description

Pulley for tensioning idler or runner roller.

The present invention relates to the field of pulley devices for tensioning idlers or runner rollers designed to interact with a chain or a belt, for examp le a distribution belt o f an internal combustion engine of a vehicle.

Such rollers are usually used to keep a constant tension on the belt or the chain in a determined range or to locally mo dify the path taken by the latter. These are called respectively tensioning idlers or runner rollers . In runner rollers, the pulley is mounted so as to rotate on a screw or a spindle by means of a rolling bearing, the ro ller then being attached directly or indirectly to the engine block or to an element of a tensioning idler device, for example an articulated arm or an eccentric.

Document GB 190509598 disclo ses a pulley comprising male and female overlapping parts which are in interlocking relation and form a cylindrical outer portion intended to be in contact with a belt.

A major disadvantage o f this pulley is that an annular recess is formed on the outer portion adapted to support the belt when the male and female parts are fastened together. There is therefore a risk of an early wear o f the belt.

It is also known, by document GB 141 829 , a pulley comprising a peripheral part intended to be in contact with a belt, an inner part and a connecting part between the inner and outer parts. With a pulley such as disclo sed, the outer part may be deformed radially inwards by bending under the action of the belt.

Document FR-A 1 -2 773 506 discloses a pulley provided with an outer jacket intended to be in contact with a belt and with an inner U-shaped ring mounted into the bore of said j acket. The inner ring has a great axial dimension. Thus, its mounting into the bore o f the outer jacket is hard to achieve. Otherwise, after mounting, the pulley has in cross section the overall shape of a U. There is therefore also a risk o f radial deformation of the outer j acket by bending. One aim o f the present invention is to overcome the aforementioned drawbacks .

It is a particular object of the present invention to provide a pulley which is easy to install onto a bearing and adapted to avoid an early wear o f the belt.

A further object of the present invention is to provide a pulley adapted to a pulley device for a tensioning idler having good rigidity in order to limit the bending of the portion in contact with the chain or the belt.

In one embodiment, the pulley suitable for a belt or chain tensioning idler or runner roller comprises an inner portion intended to be mounted on a bearing and an outer portion having a continuous outer surface intended to be in contact with the belt or the chain. The inner and outer portions o f the pulley are made in one piece. Said pulley further comprises stiffening means of the outer portion coming into contact with the inner surface or bore of said outer portion.

The stiffening means may be located radially between the bore of the outer portion and a bore of the inner portion.

Advantageously, the stiffening means extend at least partly substantially radially.

In one embodiment, the stiffening means are axially offset relative to a transverse radial plane passing through the centre of the outer portion of the pulley.

In one embodiment, the stiffening means, the inner portion and the outer portion are made in one piece. The stiffening means extend from the inner portion of the pulley, notably from the axial end of said portion. Advantageously, the stiffening means are formed by lo cal plastic deformations.

The stiffening means may be circumferentially spaced apart. In another embodiment, the stiffening means are distinct from the inner and outer portions o f the pulley.

The stiffening means may be intended to be mounted on the outer surface of the bearing. In one embodiment, the pulley is formed from a metal sheet blank.

The invention also relates to a pulley device comprising a pulley as previously defined and a ro lling bearing provided with an inner ring, an outer ring and at least one row of rolling elements disposed between said rings, the inner portion o f the pulley being mounted on the outer ring.

Illustrative and non-limiting embodiments of the present invention will be described below in detail with reference to the appended drawings, in which:

- Figure 1 is an axial section o f a pulley device according to a first embodiment of the invention,

- Figure 2 is a perspective view o f a pulley o f the device o f Figure 1 ,

- Figure 3 is an axial section o f a pulley device according to a second embodiment of the invention,

- Figure 4 is a perspective view o f a pulley o f the device o f Figure 3 , and

- Figures 5 and 6 are axial views of pulley devices according to third and fourth embodiments of the invention.

The pulley device 10 as illustrated by Figure 1 is suitable for a belt or chain tensioning idler or runner roller, and comprises a pulley 12 adapted to interact with a belt or a chain (not shown) and a rolling bearing 14 with a geometric axis 16.

The rolling bearing 14 comprises an inner ring 1 8 and an outer ring 20 between which are housed two rows of rolling elements 22 and 24, which in this case are balls, two annular cages 26, 28 respectively maintaining the circumferential spacing of the rolling elements 22, 24 and two annular seals 30, 32.

The inner and outer rings 1 8 , 20 are concentric and symmetric with respect to a transverse radial plane passing through the centre of the rolling bearing. The rings 1 8 , 20 are of the so lid type. A "so lid ring" is to be understood as a ring obtained by machining with removal of material (by machining, grinding) from metal tube stock, bar stock, rough forgings and/or rolled blanks .

The inner ring 1 8 has a bore 1 8a of cylindrical shape into which a spacer and a fastening screw (not shown) may be mounted to fasten the device 10 on an external support. The support may for example be the engine blo ck, an articulated arm or an eccentric o f the associated automatic tensioning idler. The bore 1 8a is delimited by opposite radial lateral surfaces 1 8b, 1 8c. The inner ring 1 8 also comprises an exterior cylindrical surface 1 8 d onto which first and second toroidal circular raceways (not referenced) are formed. The raceways have in cross section a concave internal pro file adapted to the rolling elements 22 and 24, the said raceways being directed radially outwards. The raceways are symmetrical with respect to the transverse radial plane passing through the centre of the rolling bearing.

The outer ring 20 comprises an outer cylindrical surface 20a delimited by opposite radial lateral surface 20b and 20c, and a bore 20d of cylindrical shape from which are formed toroidal circular raceways having in cross section a concave internal pro file adapted to the rolling elements 22 and 24, the said raceways being directed radially inwards. The lateral surfaces 1 8b and 20b, 1 8c and 20c of the inner and outer rings 1 , 2 are respectively coplanar.

The outer ring 20 also comprises two annular grooves 34, 36 formed radially towards the outside from the bore 20d, respectively in the vicinity o f the radial surfaces 20b, 20c. The grooves 34, 36 are symmetrical with one another relative to the transverse radial plane passing through the centre of the rolling bearing. Inside the said grooves are fixedly mounted the seals 30, 32 which come into contact with the cylindrical surface 1 8d of the inner ring 1 8 for preventing the ingress of undesirable external elements into the rolling bearing 14.

The seals 30, 32 are placed radially between the inner and outer rings 1 8 , 20. The seal 32 is lo cated axially between the ro lling element 22 and the radial surfaces 1 8b, 20b of the rings, the seal 30 being mounted axially between the rolling elements 24 and the radial surfaces 1 8c, 20c. A closed space is defined between the rings 1 8 , 20 and the seals 30, 32 in which the rolling elements 22, 24 are housed so as to be protected against polluting elements.

The pulley 12 comprises an axial annular outer portion 40 providing a cylindrical outer surface 40a designed to interact with the belt or the chain, an axial annular inner portion 42, and a radial annular intermediate portion 44 connecting said outer and inner portions . The portions 40, 42 are concentric and coaxial with the axis 16.

The annular outer surface 40a is continuous. A "continuous surface" is to be understood as a surface substantially smooth, i.e. devoid o f element proj ecting radially outwards like ribs, raised points, etc and devoid o f recess, cavity, etc extending radially inwards . Therefore, an early wear of the belt in contact with the outer surface 40a is limited.

The inner portion 42 comprises a cylindrical bore 42a into which the outer surface 20a of the outer ring 20 o f the rolling bearing is entirely mounted. The rolling bearing 14 may be mounted for example by push-fitting into the bore 42a. The axial length o f the inner portion 42 is greater than that o f the outer ring 20 so that said inner portion protrudes axially on the both sides of the rolling bearing 14. The outer portion 40 radially surrounds the inner portion 42 and has an axial length greater than that of said inner portion.

The pulley 12 also comprises lugs 46 extending substantially radially from the axial end of the inner portion 42 which is situated axially on the opposite side of the radial portion 44. The lugs 46 extend radially towards the outside and come into contact with a cylindrical bore 40b of the outer portion 40 radially opposite to the outer surface 40a. The lugs 46 are located in the vicinity o f the radial end surface of the outer portion 40. The lugs 46 are axially offset towards the rolling bearing 14 relative to said radial end surface. As shown on Figure 2, the lugs 46 are equally spaced apart from one another in the circumferential direction. In this instance, they are identical to one another and eight in number. Openings 48 are circumferentially formed between the lugs 46. The circumferential dimension of the lugs 46 is greater than that of the openings 48.

Advantageously, the pulley 12 is made of thin metal sheet or blank by fo lding, cutting and stamping. To obtain the lugs 46, the inner portion 42 is formed with axial extensions spaced apart from one another in the circumferential direction, said extensions being then fo lder over towards the outer portion 40 to form the lugs 46 in order that the free ends of the said lugs be into contact with the bore 40b . The deformations may be carried out by crimping in a particularly economical manner, for examp le with a crimping tool furnished with appropriate teeth. The thin metal sheet used to form the pulley 12 makes easier the lo cal plastic deformations o f the pulley 12. The pulley 12 is thus made in one piece. The free ends o f the lugs 46 may be fixed into the bore 40b of the outer portion 40 for example by caulking, crimping, radial interference or any other appropriate means.

The lugs 46 are provided to stiffen the outer portion 40 and to avoid a radial deformation inwards o f said outer portion towards the inner portion 42 by bending under the action of the belt or the chain. The lugs 46 constitute spacers extending radially from the inner portion 42 and coming into contact in radial direction with the bore 40b o f the outer portion 40. The lugs 46 press against the bore 40b in order to maintain in operating mode the radial position o f the chain or the belt in contact with the outer surface 40a of the outer portion 40.

The lugs 46 are axially offset relative to a transverse radial plane passing through the centre of the outer portion 40 and of the rolling bearing 14. More precisely, the free ends of the lugs 46 come into contact with the bore 40b of the outer portion 40 in the vicinity o f the end radial surface o f said portion situated axially on the opposite side o f the radial portion 44. Thus, the axial free end of the outer portion 40 does not bend inwards under the action o f the chain or o f the belt.

On the embodiment shown by Figures 3 and 4, in which identical parts are given identical references, the inner portion 42 o f the pulley 12 comprises deformations 50 extending radially outwards from the inner portion 42. The deformations 50 are identical to one another and have a wave-form and press against the bore 40b of the outer portion 40. More precisely, each deformation comprises a rounded portion which comes into contact in radial direction with the bore 40b . The deformations 50 are in cross section in the shape of an upside-down V. They are evenly-spaced in circumferential direction relative to one another and delimit between them circumferential openings 52. In this instance, the deformations 50 are eight in number. The deformations 50 constitute stiffening means to enhance the rigidity of the outer portion 40 and to avoid a radial bending inwards of said portion under the action o f the belt of the chain.

The deformations 50 are axially offset relative to the transverse radial plane passing through the centre of the outer portion 40 and are axially lo cated between the radial surfaces 1 8b, 20b and 1 8c, 20c o f the inner and outer rings 1 8 , 20. In this embodiment, the pulley 12 is also made in one piece.

On the embo diment shown in Figure 5 , in which identical parts are given identical references, the axial length o f the inner portion 42 is smaller than that of the outer ring 20 of the roller bearing in order that a part of the outer surface 20a of said ring remains free. A spacer 54 is provided radially between the outer surface 20a of the ring 20 and the bore 40b o f the outer portion 40 of the pulley.

The spacer 54 comprises an annular axial portion 56 fitted onto the outer surface 20a of the outer ring, and an annular radial portion 58 which radially extends outwards an axial end of the axial portion 56 situaded axially on the opposite side of the inner portion 42. The spacer 54 has in cross section an overall shape of a L . The free end o f the radial portion 58 comes into contact in radial direction with the bore 40b of the outer portion 40 of the pulley. In the illustrated embodiment, the axial portion 56 remains at a distance from the inner portion 42 of the pulley. Alternatively, the axial portion 56 may be into contact with the axial end o f said inner portion 42. The radial portion 58 is axially set back inwards relative to the radial surfaces 1 8b, 20b o f the inner and outer rings 1 8 , 20. In the embodiment shown by Figure 6, in which identical parts are given identical references, a spacer 60 is also provided radially between the outer surface 20a o f the outer ring 20 and the bore 40b o f the outer portion of the pulley. The spacer 60 comprises an annular axial portion 62 fitted onto the outer surface 20a of the outer ring, an annular radial portion 64 which radially extends outwards the axial end o f the axial portion 62 axially situated on the side of the inner portion 42 of the pulley, and an annular axial portion 66 extending axially outwards the radial portion 64. The axial portion 66 comes into contact in the radial direction with the bore 40b o f the outer portion 40. The axial portions 62, 66 remain axially at a distance from the radial surfaces 1 8b, 20b of the inner and outer rings 1 8 , 20.

In the last two embodiments, the spacers 54, 60 are axially offset relative to a transverse radial plane passing through the centre of the outer portion 40 towards the radial surfaces 1 8b, 20b of the inner and outer rings 1 8 , 20. The spacers 54, 60 may be formed from a thin metal sheet blank by fo lding, cutting and stamping, or alternatively from a synthetic material such as a polyamide. Then, the spacers 56, 60 may be disposed radially between the outer ring 20 and the bore 40b o f the outer portion in order to avoid its radial deformation inwards under the action o f the belt. Alternatively, if the axial length of the inner portion 42 of the pulley is increased, the spacer 54, 56 may be radially disposed between said portion and the outer portion 40.

It should be noted that the embodiments illustrated and described were given merely by way of non-limiting indicative examples and that modifications and variations are possible within the scope of the invention. Thus, the invention applies not only to double rows of balls but also to other types of rolling bearing, for example bearings with a single row of balls, or with at least three rows of balls. It is easily understood that it could also be possible to use bearing with other types o f rolling members such as ro llers. Furthermore, a journal or plain bearing could be also used as a variant of the rolling bearing. Otherwise, in the illustrated embodiments, the pulley is formed from a thin metal sheet blank. Alternatively, the pulley may be formed from synthetic material, for instance such as polyamide.

Claims

1 . Pulley suitable for a belt or chain tensioning idler or runner roller, the pulley comprising an inner portion (42) intended to be mounted on a bearing and an outer portion (40) having a continuous outer surface (40a) intended to be in contact with the belt or the chain, characterized in that the inner and outer portions (42, 40) are made in one piece, and in that it further comprises stiffening means (46; 50 ; 54; 60) o f the outer portion coming into contact with a bore (40b) o f said portion.

2. Pulley according to claim 1 , wherein the stiffening means

(46; 50 ; 54 ; 60) are located radially between the bore (40b) o f the outer portion and a bore (42a) of the inner portion.

3. Pulley according to claim 1 or 2 , wherein the stiffening means (46; 50 ; 54 ; 60) extend at least partly substantially radially.

4. Pulley according to any of the preceding claims, wherein the stiffening means (46; 50 ; 54 ; 60) are axially offset relative to a transverse radial plane passing through the centre of the outer portion (40) .

5. Pulley according to any o f the preceding claims, wherein the stiffening means (46; 50), the inner portion (42) and the outer portion (40) are made in one piece.

6. Pulley according to claim 5 , wherein the stiffening means (46; 50) extend from the inner portion (42) .

7. Pulley according to claim 6, wherein the stiffening means (46) extend from the axial end of the inner portion (42) .

8. Pulley according to any o f the preceding claims 5 to 7, wherein the stiffening means (46; 50) are formed by local plastic deformations.

9. Pulley according to any of the preceding claims, wherein the stiffening means (46; 50) are circumferentially spaced apart.

10. Pulley according to any o f the preceding claims 1 to 4, wherein the stiffening means (54 ; 60) are distinct from the inner and outer portions (42, 40) .

1 1 . Pulley according to any of the preceding claims, formed from a metal sheet blank.

12. Pulley device comprising a pulley according to any o f the preceding claims and a rolling bearing provided with an inner ring, an outer ring and at least one row of rolling elements disposed between said rings, the inner portion of the pulley being mounted on the outer ring.