Assembly comprising a housing, a shaft and an intermediate bearing
The bearing design with grooved surfaces and wavy rods addresses thermal expansion mismatches, reducing wear and angular displacement by accommodating thermal expansion differences, thereby enhancing the durability of electric motor assemblies.
Patent Information
- Application Number
- FR2023004800
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-05-15
- Publication Date
- 2025-04-25
- Estimated Expiration
- 2043-05-15
AI Technical Summary
The thermal expansion mismatch between the housing and the bearing in electric motors or engines leads to fretting phenomena due to the tight mounting of the bearing, which is typically made of a different material from the housing, causing angular displacement and wear.
A bearing design with an inner and outer ring featuring grooved cylindrical surfaces and interposed wavy rods that accommodate thermal expansion differences by allowing radial prestressing, reducing the risk of angular displacement and wear.
The wavy rods effectively manage thermal expansion, minimizing fretting and angular displacement between the bearing and housing, thus reducing wear and enhancing the durability of the assembly.
Smart Images
Figure 00000015_0000 
Figure 00000016_0000 
Figure 00000017_0000
Abstract
Description
Title of the invention: Assembly comprising a housing, a shaft and an interposed bearing Technical field of the invention
[0001] The present invention relates to the field of bearings used in particular in electric motors, electrical machines and associated equipment. Prior art
[0002] In an electric motor or machine, at least one bearing comprising an inner ring and an outer ring is mounted between the housing of the motor or electric machine and the rotating shaft in order to support this shaft.
[0003] During operation, when the shaft is rotating, the outer ring of the bearing in contact with the housing must be angularly fixed relative to the housing. To achieve this, the bearing is press-fitted between the housing of the motor or electrical machine and the rotating shaft.
[0004] Generally, since the bearing is made of a different material than the material forming the housing, the thermal expansion properties of the bearing and the housing are therefore different.
[0005] Thus, during the temperature rise of the motor or electrical machine, fine-tuning phenomena appear, in particular when the bearing is mounted too tightly between the housing of the motor or electrical machine and the rotating shaft.
[0006] The present invention therefore aims to remedy the aforementioned drawbacks by proposing a bearing device of simple and economical design. Summary of the invention
[0007] The invention relates to an assembly comprising a housing, a shaft and a bearing interposed radially between the shaft and an internal cylindrical surface of the housing.
[0008] The bearing is provided with an inner ring and an outer ring. The outer ring is provided with an outer cylindrical surface in contact with the inner cylindrical surface of the housing.
[0009] According to a general characteristic, at least one of the inner cylindrical surfaces of the housing and outer surface of the outer ring of the bearing is provided with a groove extending circumferentially.
[0010] The assembly further comprises at least one rod disposed in said groove formed on said cylindrical surface and in radial contact with the bottom of said groove and with said other cylindrical surface.
[0011] The rod comprises a first end and a second opposite end spaced from the first end in the circumferential direction.
[0012] The ring extends circumferentially by undulating between the bottom of said groove and said other cylindrical surface.
[0013] The ring in radial contact with the bottom of said groove and with said other cylindrical surface limits the risk of rotation of the outer ring of the bearing relative to the housing.
[0014] Said first and second ends of said reed delimit the length of said reed.
[0015] The distance between said first and second ends of said ring spaced from each other in the circumferential direction varies with temperature in order to compensate for the thermal expansions of the housing and the bearing.
[0016] The undulations of said rod allow for the creation of a radial prestress between the bearing and housing thus limiting the risk of relative angular displacement.
[0017] Advantageously, said ring is formed of a succession of sectors, each sector extending circumferentially between the bottom of said groove and said other cylindrical surface.
[0018] Said first and second ends of said rod may be located along said other cylindrical surface, radially at a distance from the bottom of said groove.
[0019] Said first and second ends of said rod located along said other cylindrical surface make it easier to mount said rod in said groove.
[0020] According to an alternative design, said first and second ends of said rod may be located along the bottom of said groove, radially at a distance from said other cylindrical surface.
[0021] According to another alternative design, said first and second ends of said rod may be located in said groove, radially away from the bottom of said groove and radially away from said other cylindrical surface.
[0022] This design promotes the deformation of said ring to compensate for the thermal expansions of the housing and the bearing.
[0023] In a particular embodiment, the housing is made of at least one first material having a first coefficient of thermal expansion, the outer ring of the bearing being made of at least one second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being strictly less than the first coefficient of thermal expansion, said ring being made of at least one third material having a third coefficient of thermal expansion, the third coefficient of thermal expansion being strictly less than the first coefficient of thermal expansion.
[0024] Thus, when the temperature increases, the bearing and said ring expand less than the housing.
[0025] Advantageously, the first coefficient of thermal expansion is at least 1.5 times greater than the second coefficient of thermal expansion at room temperature.
[0026] For example, the housing is made of aluminium and the bearing is made of steel.
[0027] According to a particular design, the third coefficient of thermal expansion is equal to the second coefficient of thermal expansion.
[0028] Advantageously, said first and second ends of said rod are curved radially towards the bottom of said groove or are rounded or are chamfered.
[0029] Thus, the said first and second ends of said rod do not risk scratching said other cylindrical surface.
[0030] Said wire may have a constant cross-section.
[0031] Advantageously, a radial clearance remains locally between the bottom of said groove and said rod or between said rod and said other cylindrical surface.
[0032] The invention also relates to a bearing device comprising a bearing equipped with an inner ring and an outer ring comprising an outer cylindrical surface.
[0033] According to a general characteristic, the outer cylindrical surface of the outer ring of the bearing is provided with at least one groove extending circumferentially.
[0034] The bearing device further comprises at least one ring disposed at least in part in said groove formed on said outer cylindrical surface of the outer ring of the bearing and in radial contact with the bottom of said groove.
[0035] Said rod comprises a first end and a second opposite end spaced from the first end in the circumferential direction.
[0036] Said reed extends circumferentially by undulating as it comes to rest against the bottom of said groove and by projecting outwards relative to the outer cylindrical surface.
[0037] Said ring of the bearing device is of identical design to that previously described.
[0038] Said ring may be formed of a succession of sectors, each sector extending circumferentially from the bottom of said groove to the outside of said groove, each sector extending radially outside of said groove.
[0039] Said first and second ends of said ring may extend outwards relative to the outer cylindrical surface of the outer ring of the bearing.
[0040] Said first and second ends of said ring extending outwards relative to the outer cylindrical surface of the outer ring of the bearing make it easier to mount said ring in said groove formed on said outer cylindrical surface of the outer ring of the bearing.
[0041] According to an alternative design, said first and second ends of said rod may be located along the bottom of said groove.
[0042] According to another alternative design, the first and second ends of the rod may be located in the groove, radially at a distance from the bottom of the groove. The rod may be made of at least the third material with a third coefficient of thermal expansion.
[0043] Said first and second ends of said rod may be curved radially towards the bottom of said groove or be rounded or be chamfered.
[0044] The present invention also relates to a method of assembling an assembly comprising a housing having an inner cylindrical surface, a shaft, a bearing having an inner ring and an outer ring, the outer ring being provided with an outer cylindrical surface, at least one of the inner cylindrical surfaces of the housing and outer cylindrical surfaces of the outer ring of the bearing being provided with a groove extending circumferentially.
[0045] According to a general characteristic, the assembly process comprises the following steps:
[0046] - a step in assembling a corrugated rod comprising a first end and a second opposite end spaced circumferentially from the first end in said groove formed on said cylindrical surface such that said rod is in radial contact with the bottom of said groove and extends circumferentially, undulating as it rests against the bottom of said groove and protrudes beyond the cylindrical surface; and
[0047] - a step of introducing the bearing into the housing so that the bearing is interposed radially between the shaft and the inner cylindrical surface of the housing, the outer cylindrical surface of the outer ring of the bearing being in contact with the inner cylindrical surface of the housing, said ring being in radial contact with the bottom of said groove and with said other cylindrical surface, said ring undulating between the bottom of said groove and said other cylindrical surface. Brief description of the figures
[0048] The present invention will be better understood upon study of the detailed description of embodiments, taken by way of non-limiting examples and illustrated by the accompanying drawings in which:
[0049] [Fig-1] is a perspective view of a landing according to a first embodiment of the invention;
[0050] [Fig.2] is a side view of the landing of [Fig. 1];
[0051] [Fig.3] is a cross-sectional view along axis III-III of [Fig.2];
[0052] [Fig.4] is a cross-sectional view along axis IV-IV of [Fig.3];
[0053] [Fig.5] is a view of an assembly including the landing of [Fig.1];
[0054] [Fig.6] is a section along the VLVI axis of [Fig.5];
[0055] [Fig.7] is a view of an assembly according to a second embodiment of the invention;
[0056] [Fig.8] is a view of an assembly according to a third embodiment of the invention; and
[0057] [Fig.9] schematically illustrates a method of assembling a set. Detailed description of the invention
[0058] The bearing device 2 illustrated in figures 1 to 4 comprises a bearing 4 equipped with an inner ring 6 and an outer ring 8 capable of rotating relative to each other around the axis X-X' of the bearing 4.
[0059] The inner and outer rings 6, 8 of the bearing 4 are concentric and extend axially along the X-X' axis of the bearing 4. The inner and outer rings 6, 8 are of the solid type. A "solid ring" is understood to be a ring 6, 8 whose shape is obtained by machining with chip removal (turning, grinding) from tubes, bars, forged and / or rolled blanks.
[0060] In the illustrated embodiment, the bearing 4 also includes a row of rolling elements 10, here balls, interposed radially between the inner and outer rings 6, 8. The bearing 4 also includes a cage 12 for maintaining the regular circumferential spacing of the rolling elements 10.
[0061] The inner ring 6 comprises a cylindrical bore 14, a cylindrical outer surface 16 radially opposed to the bore 14, and two opposing radial (not referenced) front faces axially delimiting the bore 14 and the outer surface 16. The bore 14 and the outer surface 16 delimit the radial thickness of the inner ring 6.
[0062] The inner ring 6 includes an inner raceway 18 for the rolling elements 10 formed on the outer surface 16. The raceway 18 is directed radially outwards.
[0063] The outer ring 8 comprises a cylindrical outer surface 20, a cylindrical bore 22 radially opposed to the outer surface 20, and two opposing radial (not referenced) front faces axially delimiting the bore 22 and the outer surface 20. The outer surface 20 and the bore 22 delimit the radial thickness of the outer ring 8.
[0064] The outer ring 8 includes an outer raceway 24 for the rolling elements 10 formed on the bore 22. The raceway 24 is directed radially inwards.
[0065] In the illustrated embodiment, the cylindrical outer surface 20 of the outer ring of the bearing 4 is provided with two grooves 26 axially offset from each other. The two grooves 26 have a constant cross-section. The two grooves 26 are here identical.
[0066] Each groove 26 is oriented radially outwards from the bearing 4. Each groove 26 extends circumferentially over 360°. In other words, each groove 26 is annular. Alternatively, each groove could extend over an angular sector less than 360°.
[0067] Each groove 26 has a bottom 28 which is offset radially inwards relative to the outer surface 20. Each groove 26 is also provided with two opposing lateral flanks (not referenced) which extend from the bottom 28 and connect to the outer surface 20. The flanks extend here purely radially.
[0068] The bearing device 2 also includes two identical rings 30, each ring 30 being disposed partly in one of the two grooves 26 of the outer surface 20 of the outer ring 8 of the bearing 4.
[0069] Each rod 30 comprises a first end 32 and a second end 34 which delimit in the circumferential direction the length of the rod 30.
[0070] Each rod 30 extends in the circumferential direction over an angular sector strictly less than 360°.
[0071] The first and second ends 32, 34 of each rod 30 are opposite each other.
[0072] Each rod 30 has a constant circular cross-section and a wavy shape in the circumferential direction.
[0073] Each rod 30 undulates from the bottom 28 of the groove 26 in which the rod 30 is partly disposed outside said groove 26 and projecting outwards relative to the outer surface 20. Thus, in traversing in the circumferential direction each rod 30, between the first end 32 of the rod 30 and the second end 34 of the rod 30, is several times in contact with the bottom 28 of the groove 26 in which the rod 30 is partly disposed and extends several times outside said groove 26 and projecting outwards relative to the outer surface 20.
[0074] Each rod 30 is thus formed of a succession of sectors, each sector extending in the circumferential direction from the bottom 28 of the groove 26 in which the rod 30 is partly disposed towards the outside of the groove 26.
[0075] The first and second ends 32, 34 of each rod 30 are located outside the groove 26 in which the rod 30 is partly disposed, a radial clearance 44 remaining between the bottom 28 of the groove 26 in which the rod 30 is partly disposed and the first and second ends 32, 34 of the rod 30.
[0076] The first and second ends 32, 34 of each rod 30 are rounded. Alternatively, the first and second ends 32, 34 of each rod 30 may be chamfered or radially curved inwards.
[0077] The width of each rod 30 is less than the width of the groove 26 in which The 30 reed is partially laid out.
[0078] The radial thickness of each rod 30 is less than the depth of the groove 26 in which the rod 30 is partly disposed.
[0079] The first and second ends 32, 34 of one of the two rods 30 of the bearing device 2 are here offset in the circumferential direction with respect to the first and second ends 32, 34 of the other rod 30. Alternatively, the first and second ends 32, 34 of the two rods 30 of the bearing device 2 can be aligned in the circumferential direction.
[0080] Figure 5 illustrates an assembly 36 comprising a fixed housing 38, a rotating shaft 40, with axis X-X', and the bearing device 2 interposed radially between the shaft 40 and an internal cylindrical surface 42 of the housing 38 so as to support the shaft 40.
[0081] The cylindrical inner surface 42 of the housing 38 forms the bore of the housing 38.
[0082] The outer surface 20 of the outer ring 8 of the bearing 4 is in radial contact with the cylindrical inner surface 42 of the housing 38.
[0083] Each ring 30 of the bearing device 2 undulates in the circumferential direction between the bottom 28 of the associated groove 26 and the cylindrical inner surface 42 of the housing 38.
[0084] Thus, as illustrated more visibly in [Fig.6], by traversing in the circumferential direction each rod 30, between the first end 32 of the rod 30 and the second end 34 of the rod 30, the rod 30 is in contact several times with the bottom 28 of the groove 26 in which the rod 30 is disposed and several times in contact with the cylindrical inner surface 42 of the housing 38. Thus, the rod 30 exerts a permanent radial preload force between the bearing 4 and the housing 38.
[0085] By traversing in the circumferential direction each rod 30, the sectors forming the rod 30 extend alternately from the bottom 28 of the groove 26 in which the rod 30 is disposed towards the cylindrical inner surface 42 of the housing 38 and from the cylindrical inner surface 42 of the housing 38 towards the bottom 28 of the groove 26 in which the rod 30 is disposed.
[0086] As each rod 30 travels in the circumferential direction, a play 45 remains between the bottom 28 of the groove 26 in which the rod 30 is disposed and the rod 30 or between the rod 30 and the cylindrical inner surface 42 of the housing 38.
[0087] When the bearing 4 is in a mounted state, i.e. radially interposed between the shaft 40 and the cylindrical inner surface 42 of the housing 38, the outer diameter of the two rings 30 is less than the outer diameter of these rings 30 when the bearing 4 is in a free state, i.e. not radially interposed between the shaft 40 and the cylindrical inner surface 42 of the housing 38.
[0088] The housing 38 is made of at least one first material having a first coefficient of thermal expansion. For example, the housing 38 is made of aluminum.
[0089] The outer ring 8 of the bearing 4 is made of at least one second material exhibiting a second coefficient of thermal expansion. For example, the inner and outer rings 6, 8 of the bearing 4 as well as the rolling elements 10 are made of steel.
[0090] The second coefficient of thermal expansion is strictly less than the first coefficient of thermal expansion at room temperature. For example, the coefficient of thermal expansion of steel is 12 x 10⁶ K⁻¹ at room temperature, while the coefficient of thermal expansion of aluminum at room temperature is 23 x 10⁶ K⁻¹.
[0091] Each ring 30 is made of at least one third material having a third coefficient of thermal expansion, the third coefficient of thermal expansion being strictly less than the first coefficient of thermal expansion. For example, each ring 30 is made of the same steel as the outer ring 8 of the bearing 4.
[0092] The two rings 30 deform during temperature variations in order to compensate for the forces exerted reciprocally between the bearing 4 and the housing 38, reducing the effects of fining and reducing the risk of rotation of the outer ring 8 of the bearing 4 relative to the housing 38.
[0093] The embodiment illustrated in [Fig.7], in which the identical elements bear the same references, differs mainly from the first example in that no groove is provided in the cylindrical outer surface 20 of the outer ring 8 of the bearing 4, and in that the inner surface 42 of the housing 38 opposite the bearing 4 is provided with two grooves 46.
[0094] Two rods 30 similar to the two rods 30 previously described are each inserted into one of the two grooves 46 formed in the inner surface 42 of the housing 38. The outer diameter of the two rods 30 is greater than the outer diameter of the two rods in Figures 1 to 6.
[0095] Each ring 30 of the bearing device 2 undulates in the circumferential direction between the bottom 48 of the groove 46 in which the ring 30 is disposed and the cylindrical outer surface 20 of the outer ring 8 of the bearing 4.
[0096] Thus, by traveling in the circumferential direction each ring 30, between the first end 32 of the ring 30 and the second end 34 of the ring 30, the ring 30 is several times in contact with the bottom 48 of the groove 46 in which the ring 30 is disposed and several times in contact with the cylindrical outer surface 20 of the outer ring 8 of the bearing 4.
[0097] As each circlip 30 travels in the circumferential direction, the clearance 45 remains between the bottom 28 of the groove 46 in which the circlip 30 is disposed and the circlip 30 or between the circlip 30 and the cylindrical outer surface 20 of the outer ring 8 of the bearing 4.
[0098] The embodiment illustrated in [Fig. 8], in which the identical elements bear the same reference numerals, differs from the first example in that the surface in- The outer part 42 of the housing 38 is provided with the two grooves 46.
[0099] Two rings 30 similar to the two rings 30 previously described are each inserted in part into one of the two grooves 26 of the inner surface 42 of the housing 38 and into one of the two grooves 46 of the outer surface 20 of the outer ring 8 of the bearing 4, said grooves 26, 46 being radially opposite each other.
[0100] Each ring 30 of the bearing device 2 undulates in the circumferential direction, coming radially into contact against the bottom 28 of the groove 26 in which the ring 30 is disposed and coming radially into contact against the bottom 48 of the groove 46 in which the ring 30 is disposed.
[0101] Thus, by traversing in the circumferential direction each rod 30, between the first end 32 of the rod 30 and the second end 34 of the rod 30, the rod 30 is several times in contact with the bottom 28 of the groove 26 in which the rod 30 is disposed and several times in contact with the bottom 48 of the groove 46 in which the rod 30 is partly disposed.
[0102] In the embodiment illustrated in [Fig.8], the outer surface 20 of the outer ring 8 of the bearing 4 and the inner surface 42 of the housing 38 are provided with the same number of grooves 26, 46. Alternatively, the number of grooves 26 of the outer surface 20 of the outer ring 8 of the bearing 4 may be different from the number of grooves 46 of the inner surface 42 of the housing 38.
[0103] In the illustrated embodiments, the outside diameter of each ring 30 is chosen so that the ring 30 exerts a radial force between the bottom 28 of the groove 26, 46 in which the ring 30 is at least partly disposed and the cylindrical surface of the bearing 4 or of the housing 38 radially opposite said groove 26, 46 regardless of the operating temperature of the assembly 36. Said cylindrical surface of the bearing 4 or of the housing 38 radially opposite the groove 26, 46 can be the outer surface 20 of the outer ring 8 or the cylindrical inner surface 42 of the housing 38, or the bottom 28 of the groove 26 of the outer surface 20 or the bottom 48 of the groove 46 of the cylindrical inner surface 42 of the housing 38.
[0104] In the illustrated embodiments, the bearing 4 of the bearing device 2 is provided with a single row of rolling elements 10. Alternatively, the bearing 4 may be provided with several rows of rolling elements 10. Furthermore, the rolling bearing 4 may comprise other types of rolling elements 10 than balls, for example, rollers or needles. In another embodiment, the bearing 4 may be a sliding bearing without rolling elements 10.
[0105] In the illustrated embodiments, the cross-section of the rods 30 is circular. Alternatively, the cross-section of the rods 30 may be square, rectangular, or of another shape.
[0106] In the illustrated embodiments, the width of the grooves 26, 46 is close to the width of the rods 30. Alternatively, each groove 26, 46 can be at least twice as wide as the rod 30 disposed at least partly in the groove 26, 46, the rod 30 then being able to extend over more than 360° forming a spiral.
[0107] In the illustrated embodiments, the housing 38 and the bearing 4 comprise two circumferential grooves 26, 46. Alternatively, the housing 38 and / or the bearing 4 may comprise a single circumferential groove 26, 46 or more than two circumferential grooves 26.
[0108] In the illustrated embodiments, a rod 30 is disposed at least partially in each groove 26, 46. Alternatively, several rods 30 can be disposed at least partially in the same groove 26, 46.
[0109] Figure 9 schematically illustrates a method for assembling a set 36 comprising a housing 38 having an inner cylindrical surface 42, a shaft 40, a bearing 4 having an inner ring 6 and an outer ring 8, the outer ring 8 having an outer cylindrical surface 20.
[0110] According to the first embodiment, the outer ring 8 is provided with at least one groove 26 extending circumferentially.
[0111] We begin with a step 50 of mounting a ring 30 comprising a first end 32 and a second end 34 opposite and spaced from the first end 32 in the circumferential direction in the groove 26 of the outer ring 8 so that the ring 30 is in radial contact with the bottom 28 of the groove 26 and extends circumferentially by undulating, coming radially to bear against the bottom 28 of the groove 26 and extending in projection relative to the outer surface 20 of the outer ring 8.
[0112] Then a step 52 is carried out of introducing the bearing 4 into the housing 38 so that the bearing 4 is interposed radially between the shaft 40 and the inner surface 42 of the housing 38, the outer cylindrical surface 20 of the outer ring 8 of the bearing 4 being in radial contact with the inner surface 42 of the housing 38. The circlip 30 mounted in the groove 26 of the outer ring 8 is then radially constrained between the bottom 28 of the groove 26 and the inner surface 42 of the housing 38, the first and second ends 32, 34 of the circlip 30 moving in the circumferential direction so that the circlip 30 deforms to adapt to the radial constraint. The ring 30 then undulates between its first and second ends 32, 34, being several times in radial contact with the bottom 28 of the groove 26 in which the ring is disposed and several times in radial contact with the inner surface 42 of the housing 38.
[0113] Thus, the diameter of the ring 30 in the mounted state is smaller than its diameter in the free state. The ring 30 then limits the rotation of the outer ring 8 of the bearing 4 relative to the housing 38.
[0114] According to the second embodiment, when only the cylindrical surface in the outer surface 42 of the housing 38 is provided with at least one groove 46 extending circumferentially, the assembly step 50 includes the mounting of a ring 30 in the groove 46 of the housing 38 such that the ring undulates, coming radially to bear against the bottom 48 of the groove 46 and extending in projection relative to the inner surface 42 of the housing 38, the bearing 4 introduction step 52 being carried out so that the bearing 4 is arranged axially opposite the ring 30 mounted in the groove 46 of the housing 38, the ring 30 being several times in radial contact with the bottom 48 of the groove 46 in which the ring 30 is arranged and several times in radial contact with the outer surface 20 of the outer ring 8.
[0115] According to the third embodiment, when the outer cylindrical surface 20 of the outer ring 8 of the bearing 4 is provided with at least one groove 26 and when the inner cylindrical surface 42 of the housing 38 is provided with at least one groove 46, the assembly step 50 comprises the mounting of a circlip 30 in the groove 26 of the outer ring 8 of the bearing 4 or in the groove 46 of the housing 38, the bearing 4 insertion step 52 being carried out such that the groove 26 of the outer ring 8 of the bearing 4 and the groove 46 of the housing 38 are opposite each other, the circlip 30 being both in the groove 26 of the outer ring 8 of the bearing 4 and in the groove 46 of the housing 38, the circlip 30 being in radial contact several times with the bottom 28 of the groove 26 in which the bead 30 is partly disposed and several times in radial contact with the bottom 48 of the groove 46 in which the bead 30 is partly disposed.
Claims
Claims
1. Assembly (36) comprising: - a casing (38), - a tree (40), - a bearing (4) interposed radially between the shaft (40) and an inner cylindrical surface (42) of the casing and provided with an inner ring (6) and an outer ring (8), the outer ring (8) being provided with an outer cylindrical surface (20) in contact with the inner cylindrical surface (42) of the casing, at least one of the inner cylindrical surfaces (42) of the casing and the outer cylindrical surfaces (20) of the outer ring of the bearing is provided with two grooves (26, 46) extending circumferentially, each of said grooves (26, 46) having a bottom (28, 48) which is radially offset relative to the cylindrical surface (20, 42), and two facing lateral flanks which extend from the bottom (28, 48) and which connect to said cylindrical surface (20, 42), the assembly (36) further comprising two snap rings (30) each arranged in a groove (26, 46) formed on said cylindrical surface (20, 42) and in radial contact with the bottom (28, 48) of said groove (26,46) and with said other cylindrical surface (42, 20), each of said rings (30) comprising a first end (32) and an opposite second end (34) spaced from the first end (32) in the circumferential direction, said rings (30) extending circumferentially in an undulating manner between the bottom (28, 48) of said groove (26, 46) and said other cylindrical surface (42, 20), characterized in that the first and second ends (32, 34) of each ring (30) are located outside the groove (26, 46) in which the ring (30) is partly arranged, a radial clearance (44) remaining between the bottom (28) of the groove (26) in which the ring (30) is partly arranged and the first and second ends (32, 34) of the ring (30), the first and second ends (32, 34) of one of the two rods (30) arranged in a groove (26, 46) being offset in the circumferential direction relative to the first and second ends (32,34) of the other ring (30) arranged in the other groove (26, 46).,
2. An assembly (36) according to claim 1, wherein said rod (30) is formed from a succession of sectors, each sector extending circumferentially between the bottom (28, 48) of said groove (26) and said other cylindrical surface (42, 20).
3. Assembly (36) according to any one of the preceding claims, in which the casing (38) is made at least from a first material having a first coefficient of thermal expansion, the outer ring (8) of the bearing (4) being made at least from a second material having a second coefficient of thermal expansion, the second coefficient of thermal expansion being strictly less than the first coefficient of thermal expansion, said ring (30) being made at least from a third material having a third coefficient of thermal expansion, the third coefficient of thermal expansion being strictly less than the first coefficient of thermal expansion.
4. The assembly (36) of claim 3, wherein the third coefficient of thermal expansion is equal to the second coefficient of thermal expansion.
5. An assembly (36) according to any preceding claim, wherein said first and second ends (32, 34) of said ring (30) are curved radially towards the bottom (28, 48) of said groove (26, 46) or are rounded or are chamfered.
6. An assembly (36) according to any preceding claim, wherein said wire is of constant cross-section.
7. A bearing device (2) comprising a bearing (4) provided with an inner ring (6) and an outer ring (8) comprising an outer cylindrical surface (20), the outer cylindrical surface (20) of the outer ring of the bearing being provided with two circumferentially extending grooves (26), each of said grooves (26) having a bottom (28) which is radially offset relative to the outer cylindrical surface (20), and two facing lateral flanks which extend from the bottom (28) and which connect to said cylindrical surface (20), the device (2) further comprising two snap rings (30) each arranged in a groove (26) formed on said outer cylindrical surface (20) and extending circumferentially in an undulating manner, bearing against the bottom (28) of said groove (26) and extending outwardly relative to the outer cylindrical surface (20),each of said rods (30) comprising a first end (32) and, a second opposite end (34) spaced from the first end (32) in the circumferential direction, characterized in that the first and second ends (32, 34) of each ring (30) are located outside the groove (26) in which the ring (30) is partly arranged, a radial clearance (44) remaining between the bottom (28) of the groove (26) in which the ring (30) is partly arranged and the first and second ends (32, 34) of the ring (30), the first and second ends (32, 34) of one of the two rings (30) arranged in a groove (26) being offset in the circumferential direction relative to the first and second ends (32, 34) of the other ring (30) arranged in the other groove (26).