Bearing

Abstract

Bearing (1) and its disassembly method, the bearing (1) comprising an inner ring (6) having a front surface (6.2), a frustoconical inner surface (6.1) provided with a groove (12), and a channel (14) in fluid communication with the groove (12) and opening onto the front surface (6.2). Figure 1

Description

Title of the invention: Bearing technical field

[0001] This disclosure relates to the design of a bearing for a turbomachine and a turbomachine comprising such a bearing and a method for dismantling the bearing. Previous technique

[0002] Various types of bearings exist to guide a rotating shaft. Generally, bearings consist of an inner ring mounted on a shaft, an outer ring housed in a casing, and a set of rolling elements (balls, needles, rollers, etc.) held between the inner ring and the outer ring by a cage.

[0003] The inner ring of the bearing may be shrink-fitted to the shaft and it may be necessary to use specific tools or complex techniques to replace a worn bearing without damaging the shaft.

[0004] In some cases, the shaft or housing may be drilled with channels designed to supply lubricant to the interface between the bearing and the shaft or between the bearing and the housing. The supply of lubricant can indeed be useful during operation. Furthermore, the lubricant can assist in the mounting or dismounting of the bearing when it is press-fitted onto the shaft and / or the housing. This is particularly the case when the bearing is mounted on a frustoconical surface of the shaft.

[0005] The presence of these channels is a design constraint: the dimensions or overall size of the surrounding parts may be limited by the presence of the channels, which must remain accessible for mounting and / or dismounting the bearing. Furthermore, drilling these channels along long shafts can be complex and / or costly. They also risk weakening the shafts in question.

[0006] Therefore, there is a need for an alternative design allowing more design flexibility while maintaining the advantages provided by existing solutions. Summary

[0007] The present invention aims to provide a bearing configured to be easily mounted and / or dismounted on a portion of a tapered shaft.

[0008] For this purpose, the invention relates to a bearing comprising an inner ring having a front surface, a frustoconical inner surface provided with at least one groove, and a channel in fluid communication with the groove and opening onto the front surface.

[0009] The combination of a groove on the inner surface and a channel opening onto the The front surface allows the injection of a pressurized fluid (oil, grease, etc.) to decouple the inner surface from the shaft, or even to lubricate the translational movement during the mounting or dismounting of the bearing on the shaft. This solution is less complex, less expensive, and less restrictive for the design of surrounding parts.

[0010] In the present application, "inside" or "internal" and "outside" or "external" refer to a radial position relative to the axis of symmetry of the bearing, which coincides with the axis of rotation of the shaft.

[0011] By "groove", it is appropriate to understand a withdrawal of material extending over the entire circumference of the inner ring.

[0012] The "frontal surface" may be substantially flat, except for its ends, which may be rounded or chamfered, and except for the mouth of the channel. The frontal surface describes substantially a ring perpendicular to the axis of symmetry of the bearing.

[0013] The bearing may also include, in addition to the inner ring, an outer ring, and a plurality of rolling elements (balls, needles, rollers, etc.) between the outer and inner rings. The rolling elements may be kept spaced apart from each other (in a circumferential direction) by a cage. The rolling elements roll on an internal raceway of the inner ring and an external raceway of the outer ring. The rolling elements may be arranged in one or more annular rows.

[0014] According to another aspect, the frustoconical inner surface is delimited by a first circle of a first diameter and a second circle of a second diameter larger than the first diameter, the front surface extending from the first circle. In other words, the channel opens on the side of the bearing where the inner surface of the inner ring has the smallest diameter. It can indeed be advantageous to provide an access point for injecting the pressurized fluid on the same side as the side toward which the bearing is removed.

[0015] According to another aspect, the groove has an axial width between 10% and 50% of the axial width of the frustoconical inner surface. Within this range, it is possible to counteract the shrink-fitting force by applying adequate pressure. A groove that is too narrow does not allow this. A groove that is too wide impairs the mechanical strength of the bearing.

[0016] According to another aspect, the groove is annular. It can thus distribute the pressure forces evenly around the shaft at the same axial position, which helps to limit the risk of damage to the ring or the shaft when removing the bearing.

[0017] Alternatively, the groove is helical. This geometry increases the contact area between the fluid and the shaft, allowing the pressure to be distributed over a larger area. surface, which can be advantageous for particularly wide bearings.

[0018] According to another aspect, the channel is a first channel, the inner ring comprising at least one second channel opening onto the front surface and fluidically connected to the groove. It is thus possible to accelerate the pressurization of the bearing / shaft interface by supplying fluid through several channels. In one embodiment, the two channels converge at a single opening on the front surface. The channels then allow the fluid to be rapidly distributed over the entire circumference of the groove. In another embodiment, the second channel can normally be closed by a plug and can be used if the first channel is blocked by foreign matter preventing access to the groove. The second channel can also allow access to the groove if an obstruction hinders access to the first channel.

[0019] According to another aspect, the groove is a first groove, the inner ring comprising at least a second groove. Providing several grooves allows pressure to be applied to different locations on the shaft. This can be advantageous, particularly when the bearing is wide, to provide better distributed pressure and limit the risk of shaft damage during bearing removal. The grooves may be in fluid communication with each other or be independent. They may be supplied with fluid through the same channel or through separate channels.

[0020] According to another aspect, the bearing includes a removable obturator configured to seal the channel opening at the front surface. It can indeed be advantageous to prevent impurities from entering the groove during operation. Also, when the lower ring has several channels, this allows one or more channels to be selected through which to supply the groove with fluid. The obturator can be a cap that can be clipped or screwed onto the channel opening. A sealing gasket may optionally be interposed between the obturator and the inner ring.

[0021] The invention also relates to an aircraft turbomachine comprising a shaft having a frustoconical surface and a bearing according to one of the embodiments mentioned above, the inner ring of which is press-fitted onto the frustoconical surface of the shaft. The press fit can be achieved by press fitting or shrink fitting.

[0022] The invention also relates to a method of dismantling an assembly comprising a shaft and a bearing according to one of the embodiments mentioned above, the inner ring of which is mounted tightly on the shaft, the method comprising the following steps: bringing a fluid under pressure into the groove via the channel; and moving the bearing axially relative to the shaft.

[0023] By "bringing a fluid under pressure," it is understood that a fluid is injected through the channel to the throat. A pump-type device may be connected to the channel for this purpose. This may be a hand pump. The fluid may be grease. or oil, or even water or gas. The addition of fluid has a dual effect: a mechanical effect which separates the inner surface of the inner ring from the shaft, and a tribological effect which reduces friction at the interface between the inner ring and the shaft.

[0024] The invention may also relate to a method of mounting an assembly comprising a shaft and a bearing according to one of the embodiments mentioned above, the method comprising a step of axial displacement of the bearing relative to the shaft, with or without injection of fluid into the groove. Brief description of the drawings

[0025] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0026] [Fig-1] is a schematic cross-sectional view of a bearing according to the invention;

[0027] [Fig.2] is a schematic cross-sectional view of a bearing according to the invention;

[0028] [Fig.3] is a schematic cross-sectional view of a bearing according to the invention;

[0029] [Fig.4] is a diagram of a dismantling method according to the invention. Description of the implementation methods

[0030] The figures schematically depict various aspects of the invention. The dimensions are not shown to scale: some dimensions are enlarged to facilitate reading the drawings and understanding the phenomena involved. The term "approximately," used to describe the dimensions of the various elements, is to be understood as synonymous with a tolerance of + / - 10%.

[0031] The axial direction is that of the axis of symmetry of the bearing. It is denoted A in [Fig. 1]. The radial direction is perpendicular and coplanar to the direction A. The circumferential or tangential direction is orthogonal to the axial and radial directions.

[0032] Fig. 1 shows a partial cross-sectional view of a bearing 1 mounted between a shaft 2 and a housing 4. The bearing 1 comprises an inner ring 6 whose inner surface 6.1 is in contact with the outer surface 2.1 of the shaft 2. The bearing 1 also comprises an outer ring 8 whose outer surface 8.1 is in contact with the inner surface 4.1 of the housing 4. The bearing 1 can be press-fitted (for example, by shrink fitting) onto the shaft 2 or onto the housing 4.

[0033] In this example, the inner surface 6.1 and the outer surface 2.1 of the tree are frustoconical. The half-angle at the apex of the cone can, for example, be between 1 and 20°.

[0034] The outer surface 8.1 and the inner surface 4.1 of the housing 4 can be cylindrical.

[0035] The rings 6, 8 each comprise a front surface 6.2, 8.2 and a surface rear 6.3, 8.3. These surfaces are substantially flat and each forms a ring. Thus, the front end 6.4 and rear end 6.5 of the inner surface 6.1 of the inner ring 6 are formed by circles of respective diameters dl and d2, with d2 greater than dl.

[0036] Between the inner ring 6 and the outer ring 8 are arranged rolling elements 10 in one or more annular rows. These can be kept spaced apart from each other by a cage (not shown). In [Fig. 1], a rolling element 10 is shown as a roller with axis B.

[0037] According to this disclosure, the inner ring includes a groove 12. The groove 12 is disposed on the inner surface 6.1 opposite the surface 2.1 of the shaft 2. The groove 12 may be annular or helical. The groove 12 may have a width 1 that is between 10% and 50% of the total width L of the bearing 1.

[0038] The inner ring 6 also has a channel 14 connecting the groove 12 to the front surface 6.2. The channel 14 has an opening 16 at the front surface 6.2. In the illustrated example, the channel 14 is composed of two successive bores but other configurations are possible.

[0039] Also, channel 14 is shown in the cross-sectional plane of [Fig. 1], but channel 14 may alternatively not be confined to this plane. Channel 14 may also be straight or curved. In particular, it may open tangent to the groove 12.

[0040] The mouth 16 of the channel 14 is located on the side of the front surface 6.2, that is to say the side where the inner surface 6.1 has the smallest diameter dl.

[0041] The groove 12 and the channel 14 facilitate the disassembly of the bearing. A pressurized fluid (grease, oil, water, gas, etc.) can be introduced into the groove 12 via the channel 14. In practice, an operator connects a pump to the inlet 16 of the channel 14 and then operates the pump to introduce the fluid into the groove 12 until a specific pressure is reached. This pressure helps to separate the bearing from the shaft and pushes the bearing in the direction of the slope of the frustoconical surface.

[0042] For example, a pressure of between 4000 and 6000 psi can be used in a groove of width between 3 and 5 mm to disassemble a bearing whose inner diameter is between 60 and 80 mm.

[0043] Figure 2 shows an alternative design for the bearing 1. In this example, the inner ring 6 comprises two channels 14, 24 with respective openings 16, 26 on the front surface 6.2. Each of the channels 14, 24 supplies a respective groove 12, 22. In one alternative, the two channels converge at a single opening 16 on the front surface. The use of multiple channels allows the fluid to be rapidly distributed over the entire circumference of the groove, using one or more fluid inlets.

[0044] In an unillustrated variant, the two channels 14, 24 join the same groove 12, which may be the only groove 12 of the bearing.

[0045] Fig. 3 shows a variant in which two grooves 12, 22 are connected in series to the front surface by means of two channels 14, 24.

[0046] Figure 3 also illustrates an obturator 30 that can be removably positioned at the mouth 16 of the canal 14. The obturator 30 can be a screw-on, clip-on, or otherwise fixed plug at the mouth. Once in place, the obturator 30 can prevent impurities from entering the canal 14. A seal may optionally be provided to improve the sealing of the obturator.

[0047] The different aspects discussed in relation to figures 1 to 3 can be combined with each other.

[0048] The shaft 2 is preferably a rotating shaft of a turbomachine. Indeed, the present invention falls preferably within the framework of turbomachines for aircraft, but the reader will understand that any type of use is possible with the bearing described in this disclosure.

[0049] Figure 4 shows a diagram illustrating a method 100 for dismantling bearing 1. In step 102, a pressurized fluid is introduced into the groove via the channel. This action exerts a force tending to move surface 6.1 away from surface 2.1. In step 104, bearing 1 is moved axially (along direction A, to the left in the examples illustrated in Figures 1 to 3). The pressure will drop rapidly with the movement as soon as surfaces 6.1 and 2.1 are no longer in contact. The fluid can then serve as a lubricant to reduce any friction during the removal of the bearing.

[0050] The present application has been described in the context of a frustoconical inner surface, but similar advantages can be observed with a cylindrical inner surface. Thus, in one embodiment, the inner ring has a cylindrical inner surface. All the embodiments described above can be applied to such a bearing.

[0051] Also, the present application has focused on the inner ring, but similar technical advantages can be obtained with an outer ring. Thus, in one embodiment (or in combination with the inner ring), the outer ring is provided with a groove and a channel fluidly connecting the front surface to the groove. In another embodiment, the channel of the inner ring opens onto a surface of the inner ring located on the opposite side from the surface of the outer ring onto which the channel of the outer ring opens.

Claims

Demands

1. Bearing (1) comprising an inner ring (6) having a front surface (6.2), a frustoconical inner surface (6.1) having a groove (12), and a channel (14) in fluid communication with the groove (12) and opening onto the front surface (6.2).

2. Bearing (1) according to claim 1, wherein the frustoconical inner surface (6.1) is delimited by a first circle (6.4) of a first diameter (dl) and a second circle (6.5) of a second diameter (d2) larger than the first diameter (dl), the front surface (6.2) extending from the first circle (6.4).

3. Bearing (1) according to claim 1 or 2, wherein the groove (12) has an axial width (1) between 10% and 50% of the axial width (L) of the frustoconical inner surface (6.1).

4. Bearing (1) according to any one of claims 1 to 3, wherein the groove (12) is annular.

5. Bearing (1) according to any one of claims 1 to 3, wherein the groove (12) is helical.

6. Bearing (1) according to any one of claims 1 to 5, wherein the channel (14) is a first channel (14), the inner ring (6) comprising at least a second channel (24) opening onto the front surface (6.2) and fluidly connected to the groove (12).

7. Bearing (1) according to any one of claims 1 to 6, wherein the groove (12) is a first groove (12), the inner ring (6) comprising at least a second groove (22).

8. Bearing (1) according to any one of claims 1 to 7, comprising a removable obturator (30) configured to obturate the mouth (16) of the channel (14) at the front surface (6.2).

9. Aircraft turbomachine comprising a shaft (2) having a frustoconical surface (2.1) and a bearing (1) according to any one of the preceding claims, the inner ring (6) of which is press-fitted onto the frustoconical surface (2.1) of the shaft (2).

10. A method (100) for dismantling an assembly comprising a shaft (2) and a bearing (1) according to any one of the preceding claims, the inner ring (6) of which is press-fitted onto the shaft (2), the method comprising the following steps: - supplying (102) a pressurized fluid into the groove (12) via the channel (14); and move (104) axially the bearing (1) relative to the shaft (2).

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