WO2015181466A1

WO2015181466A1 - Bearing system with an integrated back-up bearing

Info

Publication number: WO2015181466A1
Application number: PCT/FR2015/051300
Authority: WO
Inventors: Claude CHUDZIK
Original assignee: Societe De Motorisations Aeronautiques
Priority date: 2014-05-26
Filing date: 2015-05-19
Publication date: 2015-12-03
Also published as: FR3021374A1; FR3021374B1

Abstract

The bearing system with an integrated back-up bearing comprises a first ring (2) mounted on a rotating shaft (1), a second ring (3) rigidly connected to a fixed frame (10) and first and second series of rolling members (4a, 4b) interposed between the first and second rings (2, 3) and lubricating members (31, 32) for lubricating the first and second series of rolling members (4a, 4b). The system further comprises a backup journal bearing (5) interposed between the first and second rings (2, 3) and between the first and second series of rolling members (4a, 4b), and the lubricating members (31, 32, 33) are produced in such a way as to interpose an oil film in the clearances (8, 9) provided between the first ring (2) and the backup journal bearing (5) and between the second ring (3) and the backup journal bearing (5), the clearance (8) provided between the backup journal bearing (5) and the first ring (2) being greater than the operating clearance of the first and second series of rolling members (4a, 4b) in the entire thermal operating range of the bearing system.

Description

Integrated Bearing Bearing System

Field of the invention

The present invention relates to an integrated emergency bearing bearing system, comprising a first ring mounted on a rotating shaft, a second ring secured to a fixed frame, first and second series of rolling members interposed between the first and second rings, and lubrication means of the first and second series of rolling members, the first and second series of rolling members being spaced apart from each other along an axis of the rotating shaft of to define a double-acting rolling system.

Prior art

Rotating shaft support bearing systems may be subject to failure, particularly due to bearing wear.

When a rolling system supports for example a turbocharger shaft fitted to an aircraft, a failure of this rolling system can have very damaging consequences.

In most cases, the consequences of this failure result in the loss of guiding and maintaining the rotating parts that come into contact with the fixed parts.

This causes a sudden drop in the rotational speed with loss of air flow and therefore the power of turbomachines or supercharged engines, as well as associated events such as rupture and loss of vanes of the compressor wheel and the turbine, or the introduction of vibrations by the appearance of strong unbalance.

In particular applications using a turbocharger, a turbomachine or a reactor, it is imperative to avoid any risk of this type of damage.

It has already been proposed to equip turbine engines with emergency bearings, but these are positioned outside the rolling systems and are generally bearings with metal bearings. This This technology is not suitable for bearings with a high rotational speed and small footprint, as is the case for bearings used in turbochargers supercharging engines, for example.

In addition, the existing emergency bearings used on turbomachines are mainly intended to avoid the risk of an explosive rupture of the blades in case of bearing damage. They do not allow a priori operation in degraded mode. The existing technology is cumbersome and does not allow damping the tree vibration modes including in the case of normal operation.

Object and brief description of the invention

The present invention aims to overcome the aforementioned drawbacks of known bearing systems.

More particularly, the invention aims to provide a compact integrated emergency bearing bearing system which is suitable for shafts rotating at high rotation speed and allows, firstly in normal operation (when the priority guidance is ensured by the bearings) and on the other hand in degraded mode (when the bearings have a pronounced wear or a failure), to create a damping of the vibrations of the shaft or to counter an accidental unbalance.

These goals are achieved by means of an integrated emergency bearing system comprising a first ring mounted on a rotating shaft, a second ring secured to a fixed frame, first and second series of rolling members interposed between the first and second rings. and second rings, the first and second sets of rolling members being spaced from each other along an axis of the rotating shaft so as to define a double-acting rolling system, and means for lubricating said first and second series of rolling members, characterized in that it further comprises a relief sliding bearing interposed on the one hand between said first and second rings and on the other hand between the first and second series of rolling members, in that the means of lubrication are made in such a way as to ensure the interposition of an oil film in games formed on the one hand between the first ring and the emergency sliding bearing and, on the other hand, between the second ring and the relief plain bearing, the clearance between the emergency sliding bearing and the first ring being greater than the functional clearance of the first and second series of rolling members throughout the thermal operating range of the rolling system, in that abutments are formed on the first ring on the one hand between the first set of rolling elements and the emergency sliding bearing and, on the other hand, between the second set of rolling elements and the emergency sliding bearing, and in that the lubricating means comprise orifices formed in the second ring, either facing open spaces formed between said stops and the relief plain bearing, or facing holes formed in the relief plain bearing.

The emergency sliding bearing is made of a material with a low coefficient of friction and may for example be made of spongy bronze.

According to one aspect of the present invention, the system further comprises sensors of physical quantities arranged on the second ring in the vicinity of the relief smooth bearing and a monitoring system for detecting malfunctions measured by said sensors.

In this case, the physical quantity sensors may comprise at least one temperature measuring sensor, a functional clearance loss measuring sensor, a contact pressure measurement sensor on the emergency sliding bearing or an accelerometer.

According to a first possible embodiment, the first ring is an inner ring and the second ring is an outer ring.

According to a second possible embodiment, the first ring is an outer ring and the second ring is an inner ring.

According to an advantageous embodiment, the first ring is made in two parts contiguous axially in a central zone located between the first and second series of rolling members. The system according to the invention can be applied in particular to the support of the shaft of a turbocompressor, so as to allow operation of the turbocharger in degraded mode on the relief slide bearing in the event of failure of the first series of members running gear or the second set of running gear.

In general, an integrated emergency bearing bearing system according to the invention can be used to guide rotating assemblies in a wide range including in particular heat engines, electric motors, pumps, or more generally any system with rotating parts, whether with a rotating inner ring bearing or a rotating outer ring bearing technology.

The system according to the invention is simplified with respect to a more complex complete redundancy system to be implemented consisting of doubling the sets of rolling elements.

Brief description of the drawings

Other features and advantages of the invention will emerge from the following description of particular embodiments given by way of non-limiting example with reference to the accompanying drawings, in which:

- Figure 1 is a schematic axial sectional view of an exemplary integrated bearing bearing system according to the invention.

Detailed description of particular embodiments

Referring to Figure 1, we see the principle of an integrated bearing bearing system realized in accordance with the invention.

The rolling system comprises a first ring 2 which is mounted on a rotating shaft 1 and can advantageously be made in two parts 21, 22 contiguous axially in a median zone situated between first and second series of rolling members 4a, 4b, such as balls, which are interposed between the first ring 2 and a second ring 3 integral with a fixed frame 10. The two parts 21, 22 are locked axially on the rotating shaft 1.

The first and second series of rolling members 4a, 4b interposed between the first and second rings 2, 3, are spaced from each other along an axis X'-X of the rotating shaft 1 of to define a double-acting rolling system. Orifices 31, 32 are formed in the second ring 3 to lubricate the first and second series of rolling members 4a, 4b.

According to the invention, a relief sliding bearing 5 is interposed on the one hand between the first and second rings 2, 3 and on the other hand between the first and second series of rolling members 4a, 4b.

The relief sliding bearing 5 is made of a material with a low coefficient of friction and may be made for example of spongy bronze.

The lubricating orifices 31, 32 formed in the second ring 3 in the vicinity of the two sets of rolling members 4a, 4b and one or more additional lubrication orifices 33 formed in the second ring 3 in the zone between the two series of rolling members 4a, 4b are made so as to ensure the interposition of a film of oil in sets 8, 9 formed on the one hand between the first ring 2 and the relief sliding bearing 5 and other part between the second ring 3 and the relief plain bearing 5.

The clearance 8 formed between the relief sliding bearing 5 and the first rotating ring 2 is greater than the functional clearance of the first and second series of rolling members 4a, 4b throughout the thermal operating range of the rolling system.

Stoppers 6, 7 are preferably formed on the first ring 2 on the one hand between the first series of rolling elements 4a and the relief sliding bearing 5 and on the other hand between the second series of rolling elements 4b. and the emergency support bearing 5.

The lubrication holes 31, 32 formed in the second ring 3 in the vicinity of the two sets of rolling members 4a, 4b being oriented towards the tracks of the rolling members are also opposite free spaces 61, 71 formed between the stops 6, 7 and the relief sliding bearing 5. The orifices 33 formed in the second ring 3 in a central zone are also arranged in view of orifices 51 formed in the relief sliding bearing 5 to ensure lubrication of the portion of the sliding bearing may be in contact with the rotating elements (rotating half-rings 21, 22).

The stops 6, 7 play in particular a barrier role against the metal particles generated by the degradation of the rolling system, and contribute to maintaining the effectiveness of the central lubrication principle through the orifices 33, 51. The rolling system according to the The invention is thus more robust with regard to possible pollution of the lubricating oil by metal particles or silica, for example, which may originate from the degradation of the rolling elements 4a, 4b or associated raceways.

With the orifices or free spaces of lubrication 31, 32, 33 and 61, 71, 51, a permanent film of oil ensures the lubrication of the plain bearing 5 which may possibly be in contact with the rotating part 2. The oil pressure around the plain bearing also makes it possible to prevent pollution of the emergency bearing by the particles coming from the bearings.

The sliding bearing 5 can thus operate as a crushed film damper ("squeeze film" in English) by a metering and a distribution of the oil flow derived from a main supply circuit and introduced in the games 8 and 9. Sets 8 and 9 of the emergency bearing range 5 / rings 21, 22 and emergency bearing 5 / ring 3 are defined to ensure the damping function of the rotating assembly and to limit the vibration fatigue of the rolling parts of the bearing.

The rolling system according to the invention further comprises sensors 11, 12 of physical quantities arranged on the second ring 3 in the vicinity of the relief smooth bearing 5 and a monitoring system 13 intended to detect malfunctions measured by the sensors 11, 12.

The physical quantity sensors 11, 12 comprise at least one temperature measuring sensor, a functional clearance loss measuring sensor, a contact pressure measuring sensor on the emergency sliding bearing 5 or an accelerometer. The signals delivered by the sensors 11, 12 are processed by the monitoring system 13 which records the detection of malfunctions and can trigger an alarm to inform a user of the degradation of the bearing. Thus, according to the invention, there is introduced into the rolling system a sliding bearing 5 having a coefficient of friction as small as possible on the non-rotating part of the rolling system (ring 3). A clearance 8 is formed at least between the sliding bearing 5 and the rotating part (ring 2), this clearance 8 being greater than the functional clearance of the rolling system throughout the thermal operating range, that is to say whatever are the dilations in this operating range.

The sliding bearing 5 comes into action in case of loss of centering of the moving parts. The lubrication is permanent and results from a leakage flow derived from the lubrication flow of the rolling elements 4a, 4b of the rolling system.

In normal operation (when the priority guidance is provided by the bearings 4a, 4b) and secondly in degraded mode (when the bearings 4a, 4b have a pronounced wear or failure), it is created a vibration damping of the 1 with the hydrodynamic film formed in the space 9 between the emergency bearing 5 and the ring 3 and the hydrodynamic film formed in the space 8 between the emergency bearing 5 and the half-rings 21, 22. The invention also makes it possible to counter an accidental unbalance.

In Figure 1, there is shown an inner rotating ring 2 and an outer fixed ring 3. However, the invention applies in the same way to the case of a bearing system comprising an outer hollow shaft and an inner fixed frame, such as a mandrel, that is to say a system comprising a rotating ring. outer and an inner fixed ring.

In the case where the invention is applied for example to an aircraft turbocharger, it is possible to prolong the degraded operation of the turbocharger having a bearing bearing failure and to allow the pilot of the aircraft to have sufficient time to handle the incident.

The invention thus consists in introducing, within a bearing rolling system, a sliding bearing 5 which, in the event of the rolling elements 4a, 4b, degrade, has the guiding and holding function normally provided by the elements. 4a, 4b and the tracks formed on the rings 2 and 3 to cooperate with the elements of bearing 4a, 4b. A user can be warned of a malfunction by the monitoring system 13 which monitors the rolling system with the aid of one or more sensors 11, 12 intended in particular to measure the clearance, the stress at the level of the bearing. relief or temperature.

The invention can be applied in a wide variety of ways to all rolling bearing systems intended to guide rotary assemblies, in particular for thermal engines, electric motors, pumps or any system having rotating parts, whether either with a rotating inner ring technology, as shown in Figure 1 or with a rotating outer ring technology, for which the invention can be applied in the same manner.

Claims

1. integrated bearing bearing system, comprising a first ring (2) mounted on a rotating shaft (1), a second ring (3) integral with a fixed frame (10), first and second series of rolling members (4a, 4b) interposed between the first and second rings (2, 3), the first and second sets of rolling members (4a, 4b) being spaced apart from one another along an axis (X'-X) of the rotating shaft (1) so as to define a double-acting rolling system, and means (31, 32) for lubricating said first and second series of rolling members (4a, 4b), characterized in that it further comprises a relief sliding bearing (5) interposed on the one hand between said first and second rings (2, 3) and on the other hand between the first and second series of members (4a, 4b), in that the lubricating means (31, 32, 33) are designed to interpose an oil film. e in sets (8, 9) formed on the one hand between the first ring (2) and the relief plain bearing (5) and on the other hand between the second ring (3) and the relief plain bearing (5). ), the clearance (8) formed between the relief sliding bearing (5) and the first ring (2) being greater than the functional clearance of the first and second series of rolling members (4a, 4b) throughout the operating range thermal of the rolling system, in that abutments (6, 7) are formed on the first ring (2) on the one hand between the first set of rolling elements (4a) and the emergency sliding bearing (5) and secondly between the second series of rolling elements (4b) and the emergency sliding bearing (5) and in that the lubricating means comprise orifices (31, 32, 33) formed in the second ring ( 3) facing open spaces (61, 71) formed between said abutments (6, 7) and the relief sliding bearing (5), or facing openings (51) formed in s the emergency support bearing (5).

2. System according to claim 1, characterized in that the relief sliding bearing (5) is made of a material with a low coefficient of friction.

3. System according to any one of claims 1 and 2, characterized in that it further comprises sensors (11, 12) of physical quantities disposed on the second ring (3) in the vicinity of the relief slide bearing (5). ) and a monitoring system (13) for detecting malfunctions measured by said sensors (11, 12).

System according to Claim 3, characterized in that the sensors (11, 12) of physical quantities comprise at least one temperature measuring sensor, a functional clearance loss measuring sensor, a contact pressure measuring sensor. on the emergency plain bearing or an accelerometer (5).

5. System according to any one of claims 1 to 4, characterized in that the first ring (2) is an inner ring and the second ring (3) is an outer ring.

6. System according to any one of claims 1 to 4, characterized in that the first ring is an outer ring and the second ring is an inner ring.

7. System according to any one of claims 1 to 6, characterized in that the first ring (2) is formed in two parts (21, 22) contiguous axially in a central zone between the first and second series of organs rolling (4a, 4b).

8. System according to any one of claims 1 to 7, characterized in that it is applied to the support of the shaft of a turbocharger so as to allow operation of the turbocharger in degraded mode on the emergency support bearing ( 5) in case of failure of the first set of rolling members (4a) or the second set of rolling members (4b).