Rolling

Abstract

Bearing (1) and method of disassembling it, 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) Abstract figure: Figure 1

Description

Title of the invention: Bearing Technical field

[0001] The present disclosure relates to the design of a bearing for a turbomachine as well as a turbomachine comprising such a bearing and a method of dismantling the bearing. Prior art

[0002] Various types of bearings exist to guide a rotating shaft. Generally, bearings are formed of an inner ring mounted on a shaft, an outer ring housed in a housing, and a set of rolling members (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 the housing may be pierced with channels intended to bring a 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. Also, the lubricant can assist the assembly or disassembly of the bearing when it is mounted tightly on the shaft and / or on the housing. This is the case in particular 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 bulk of the surrounding parts may be constrained by the presence of the channels which must remain accessible for mounting and / or dismounting the bearing. Also, drilling these channels along long shafts may be complex and / or expensive. They also risk weakening the shafts concerned.

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

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

[0008] To this end, 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.) in order to separate the inner surface of the shaft, or even lubricate the translational movement during assembly or disassembly of the bearing on the shaft. This solution is less complex, less expensive and less restrictive for the design of the surrounding parts.

[0010] In the present application, "inner" or "internal" and "outer" 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" is meant 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 front surface substantially describes a ring perpendicular to the axis of symmetry of the bearing.

[0013] The bearing may also comprise, in addition to the inner ring, an outer ring, and a plurality of rolling members (balls, needles, rollers, etc.), between the outer ring and the inner ring. The rolling members may be kept spaced from each other (in a circumferential direction) by a cage. The rolling members roll on an inner raceway of the inner ring and an outer raceway of the outer ring. The rolling members 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 may indeed be advantageous to provide access for injecting the pressurized fluid on the same side as the side towards which the bearing is removed.

[0015] According to another aspect, the groove has an axial width of between 10% and 50% of the axial width of the frustoconical inner surface. It is possible within this range of values ​​to counteract the hooping force by 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 equally around the shaft at the same axial position, which makes it possible to limit the risks of damage to the ring or the shaft when removing the bearing.

[0017] Alternatively, the groove is helical. This geometry increases the contact surface between the fluid and the shaft, allowing the pressure to be distributed over a greater 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 via several channels. In one variant, the two channels converge towards a single opening on the front surface. The channels then make it possible to quickly distribute the fluid over the entire circumference of the groove. In another variant, the second channel can be normally closed by a shutter and it can be used if the first channel is blocked by foreign bodies preventing access to the groove. The second channel can also allow access to the groove if an obstacle hinders access to the first channel.

[0019] According to another aspect, the groove is a first groove, the inner ring comprising at least one second groove. Providing several grooves makes it possible to apply pressure to different locations of the shaft. This can be advantageous in particular when the bearing is wide to provide better distributed pressure and limit the risks of damage to the shaft when removing the bearing. The grooves can be in fluid communication with each other or be independent. They can be supplied with fluid by the same channel or by separate channels.

[0020] According to another aspect, the bearing comprises a removable shutter configured to close the mouth of the channel at the front surface. It may indeed be advantageous not to allow impurities to penetrate into the groove during operation. Also, when the lower ring is provided with several channels, this makes it possible to choose one or more channels through which to supply the groove with fluid. The shutter may be a cap which can be clipped or screwed to the mouth of the channel. A seal may optionally be interposed between the shutter and the inner ring.

[0021] The invention also relates to a turbomachine for an aircraft comprising a shaft having a frustoconical surface and a bearing according to one of the embodiments mentioned above, the inner ring of which is mounted tightly on the frustoconical surface of the shaft. The tight mounting can be obtained by press mounting or by shrink fitting.

[0022] The invention also relates to a method for 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: supplying a pressurized fluid into the groove via the channel; and axially moving the bearing relative to the shaft.

[0023] By "supplying a fluid under pressure" it is meant 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 double 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 characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

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

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

[0028] [Fig.3] is a schematic 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 embodiments

[0030] The figures describe different aspects of the invention in a schematic manner. The dimensions are not shown to scale: certain dimensions are enlarged to facilitate reading of the drawings and understanding of the phenomena involved. The term “approximately”, used to describe the dimensions of the various elements, is to be considered 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.l]. The radial direction is perpendicular and coplanar to direction A. The circumferential or tangential direction is orthogonal to the axial direction and to the radial direction.

[0032] [Fig.l] shows a partial 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 mounted tightly (for example by shrink fitting) on ​​the shaft 2 or on the housing 4.

[0033] In this example, the inner surface 6.1 and the outer surface 2.1 of the shaft 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 casing 4 may 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 form a ring. Thus, the front 6.4 and rear 6.5 ends 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 members 10 arranged in one or more annular rows. These may be kept spaced apart from each other by a cage (not shown). In [Fig.l], a rolling member 10 is shown in the form of a roller with an axis B.

[0037] According to the present disclosure, the inner ring comprises a groove 12. The groove 12 is arranged 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 which 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 a mouth 16 at the front surface 6.2. In the example illustrated, the channel 14 is composed of two successive holes but other configurations are possible.

[0039] Also, the channel 14 is shown in the section plane of [Fig.l] but the channel 14 may alternatively not be confined to this plane. The channel 14 may also be rectilinear or curved. In particular, it may open tangentially into 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 make it easier to disassemble the bearing. Indeed, a fluid (grease, oil, water, gas, etc.) under pressure can be brought into the groove 12 via the channel 14. In practice, an operator will connect a pump to the mouth 16 of the channel 14, then operate the pump to introduce the fluid into the groove 12 until a given pressure is obtained in the groove. The pressure will help to separate the bearing from the shaft and will push the bearing in the direction of the slope of the frustoconical surface.

[0042] For example, a pressure of between 4000 and 6000 psi may be used in a groove of width between 3 and 5 mm to dismount a bearing having an inside diameter of between 60 and 80 mm.

[0043] [Fig. 2] shows a design variant for the bearing 1. In this example, the inner ring 6 comprises two channels 14, 24 with a respective mouth 16, 26 on the front surface 6.2. Each of the channels 14, 24 serves to feed a respective groove 12, 22. In one variant, the two channels converge to a single mouth 16 on the front surface. The use of several channels allows the fluid to be quickly distributed over the entire circumference of the groove, using one or more fluid inlets.

[0044] In a variant not illustrated, 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] [Fig. 3] also illustrates a shutter 30 which may be removably disposed at the mouth 16 of the channel 14. The shutter 30 may be a plug screwed, clipped or otherwise secured to the mouth. Once in place, the shutter 30 may prevent impurities from entering the channel 14. A seal may optionally be provided to improve the sealing of the shutter.

[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 preferably falls within the scope of turbomachines for aircraft but the reader will understand that any type of use is possible with the bearing of the present disclosure.

[0049] [Fig. 4] shows a diagram presenting a method 100 for dismantling the bearing 1. In step 102, a pressurized fluid is supplied into the groove via the channel. This action makes it possible to exert a force tending to move the surface 6.1 away from the surface 2.1. In step 104, the bearing 1 is moved axially (in 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 the surfaces 6.1 and 2.1 are no longer in contact. The fluid can then serve as a lubricant to reduce any friction while the bearing is being removed.

[0050] The present application has been described in the context of a frustoconical inner surface but similar advantages may appear with a cylindrical inner surface. Thus, in one variant, 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 when it is an outer ring. Thus, in one variant (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 one variant, the channel of the inner ring opens onto a surface of the inner ring which is located on the opposite side to the surface of the outer ring onto which the channel of the outer ring opens.

Claims

Claims

1. 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).

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) of between 10% and 50% of the axial width (L) of the frustoconical inner surface (6.1).

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

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

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

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

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

9. Turbomachine for aircraft comprising a shaft (2) having a frustoconical surface (2.1) and a bearing (1) according to one of the preceding claims, the inner ring (6) of which is mounted tightly on the frustoconical surface (2.1) of the shaft (2).

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

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