FR3122711A1 - Rolling bearing including a compartmentalized oil film compression damper - Google Patents

Abstract

The invention relates to a rolling bearing (20) comprising a cavity (60) forming compartments (60A, 60B) which succeed each other axially so as to form a fluidic damping film having several adjacent sections. Figure for abstract: Fig. 2

Description

Rolling bearing including a compartmentalized oil film compression damper

The invention relates to the field of rolling bearings for turbomachines or other rotating machines, in particular for an aircraft propulsion system.

State of the prior art

A conventional aircraft turbine engine comprises at least one shaft and a device for guiding this shaft in rotation comprising at least one rolling bearing mounted on flexible suspension equipped with an oil film compression damper, known as Anglo-Saxon “squeeze-film damper”. Such a damper makes it possible to dampen the vibrations of the shaft caused by its rotation and by the imbalance of its mechanical loading.

Document EP 1 650 449 A1 describes such a guiding device.

The effectiveness of oil film compression dampers known in the state of the prior art generally depends, with fixed radial clearance, mainly on the axial dimension of the cavity receiving the fluid and forming the film so that the increase the damping performance may require an extension of this cavity, which is not always possible given the space available.

In addition, the optimal level of damping may vary depending on the operating phases of the machine. To this end, it is known to modify the oil supply pressure according to such operating phases.

Controlling the supply pressure is however likely to degrade the operation of the damper and the bearing if the pressure level is too low, which can lead to a cavitation phenomenon.

There is therefore a need to provide an effective variable damper which in particular makes it possible to reduce the risk of cavitation and/or which does not require increasing the length of the cavity.

To this end, the subject of the invention is a bearing for guiding a rotating machine shaft in rotation around an axis, comprising a first part forming a rolling ring or being intended to be secured to a rolling ring of the bearing, and a second part intended to be connected to a casing of the rotating machine, the first part and the second part defining radially between them an annular cavity configured to receive at least one pressurized fluid so as to radially damp a relative displacement of the first piece relative to the second piece. According to the invention, the cavity comprises at least two compartments axially spaced with respect to each other, a first of said compartments being configured to receive a first part of the at least one fluid, a second of said compartments being configured to receiving a second portion of the at least one fluid.

Such a bearing makes it possible to control the flow rate and the fluid supply pressure separately for each of the compartments, in particular according to the different operating phases of the machine.

The invention thus makes it possible to improve the effectiveness of the radial damping over a greater operating range while reducing the risk of cavitation.

Preferably, the bearing comprises at least one sealing member disposed radially between the first part and the second part so as to axially delimit at least one of the compartments.

According to a first variant embodiment, the sealing member delimits the first compartment axially downstream and the second compartment axially upstream.

In the present description, it is considered that the first compartment and the second compartment are thus axially contiguous.

According to a second variant embodiment, said sealing member forms a first sealing member axially delimiting the first compartment downstream, the bearing comprising a second sealing member axially delimiting the second compartment upstream.

Preferably, in the context of this second variant, the first and the second sealing member are axially spaced with respect to each other.

In the present description, it is considered that, according to such an arrangement, the first compartment and the second compartment are not axially contiguous, because a space separates these two sealing members.

Of course, the invention also covers the case in which the first and the second sealing member are axially joined. In this case, it can be considered that the first compartment and the second compartment would be axially contiguous.

In one embodiment, the second part comprises one or more first supply orifices configured to introduce the at least one fluid into the first compartment of the cavity and one or more second supply orifices configured to introduce the at least a fluid in the second compartment of the cavity.

In one embodiment, the bearing, or an assembly comprising a bearing as described above, comprises at least one part forming one or more supply conduits configured to convey the at least one fluid to the first and second compartments of the cavity via the first and second supply ports.

Preferably, a first of said supply ducts is configured to route the at least one fluid to the first compartment of the cavity via the first supply orifice(s), and a second of said supply ducts is configured to route the at least one fluid to the second compartment of the cavity via the second supply port(s).

Said at least one fluid used to supply the cavity can be the same for the different compartments. In this case, a first part of this common fluid can be introduced into the first compartment, for example via said first supply conduit and the said first supply orifice(s), and a second part of this common fluid can be introduced into the second compartment, for example via said second supply duct and said second supply port(s).

Alternatively, separate fluids and/or from a separate power source can be introduced into the different compartments of the cavity. Thus, a first fluid can be introduced into the first compartment, for example via said first supply conduit and said first supply port(s), and a second fluid can be introduced into the second compartment, for example via said second conduit feed port and said second feed port(s).

In all cases, the invention makes it possible to separately control the pressure and/or the flow rate of fluid in each of the compartments.

The invention also relates to an assembly comprising a bearing as described above.

In one embodiment, this assembly comprises at least one pressure and/or flow regulator for the at least one fluid.

According to a first variant, the at least one regulator is common for adjusting the pressure and the flow rate of the fluids or parts of fluid introduced into the various compartments.

According to a second variant, said at least one regulator comprises a first pressure and/or flow regulator for the fluid, or part of the fluid, introduced into the first compartment of the cavity and a second pressure and/or flow regulator fluid, or part of fluid, introduced into the second compartment of the cavity.

The invention also relates to a rotating machine comprising a shaft and a bearing as described above for guiding the shaft in rotation around an axis.

In one embodiment, said second part is connected to the casing of the rotating machine via a deformable element having a determined stiffness.

In one embodiment, the rotating machine is a turbomachine.

The invention also relates to a propulsion assembly for an aircraft, comprising such a turbine engine, as well as an aircraft equipped with such a propulsion assembly.

According to another aspect, the invention relates to a method for introducing at least one fluid into the compartments of the cavity of a bearing as described above.

According to a first implementation variant, this method comprises a step of introducing a first part of a fluid into the first compartment and a step of introducing a second part of said fluid into the second compartment.

According to a second implementation variant, this method comprises a step of introducing a first fluid into the first compartment and a step of introducing a second fluid distinct from the first fluid into the second compartment.

In one embodiment, the method comprises a pressure and/or flow control step of the at least one fluid introduced into the compartments of the cavity, preferably using the at least one regulator described above. -above.

Other advantages and characteristics of the invention will appear on reading the detailed, non-limiting description which follows.

The following detailed description refers to the attached drawings in which:

is a schematic view in longitudinal half-section of a turbojet engine according to the invention;

is a schematic view in longitudinal section of a bearing according to a first embodiment of the invention;

is a schematic view in longitudinal section of a bearing according to a second embodiment of the invention.

Detailed description of embodiments

There is shown in Figure 1 a turbofan engine 1 and double body.

Subsequently, the terms "upstream" and "downstream" are considered according to a direction S1 of main gas flow through the turbojet engine 1.

The turbojet engine 1 conventionally comprises a gas generator 2 forming, from upstream to downstream, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6 and a low-pressure turbine pressure 7.

The low pressure compressor 3 and the low pressure turbine 7 form a low pressure body and are connected to each other by a low pressure shaft 8 centered on a central longitudinal axis A1 of the turbojet engine 1. Similarly, the high pressure compressor 4 and the high pressure turbine 6 form a high pressure body and are connected to each other by a high pressure shaft 9 centered on the axis A1 and arranged around the low pressure shaft 8.

The turbojet 1 also comprises, upstream of the gas generator 2, a fan 10 which is here arranged directly behind an air inlet cone of the engine. The fan 10 is rotatable along the axis A1 and is surrounded by a fan casing 11. It is driven indirectly by the low pressure shaft 8, via a speed reducer 12.

In addition, conventionally, the turbojet engine 1 defines a primary stream 16 intended to be traversed by a primary flow, as well as a secondary stream 18 intended to be traversed by a secondary flow located radially outwards with respect to the primary flow. .

The two shafts 8 and 9 as well as the hub of the fan 10 are guided in rotation by means of bearings 20 supported by casings of the turbojet engine 1. At least one of these bearings 20 conforms to one of the modes implementation described below.

Figure 2 shows a bearing 20 according to the invention.

In this example, the bearing 20 is intended to provide guidance in rotation around the axis A1 of the high pressure shaft 9. Of course, this bearing 20 can be implemented in a similar manner in the turbojet engine 1 of FIG. 1 in order to guide the low pressure shaft 8 or within another type of rotating machine.

The bearing 20 comprises on the one hand a rolling member formed by an inner rolling ring 21, an outer rolling ring 22 and rolling elements 23 extending radially between the rings 21 and 22.

In a manner known per se, each of the rings 21 and 22 forms a rolling track of the rolling elements 23, the latter being circumferentially spaced around the axis A1 by means of a separator cage (not shown).

The rolling elements 23 are rollers here.

Alternatively, the rolling elements 23 can be balls arranged to form a ball bearing with two, three or four points of contact.

Each of the rings 21 and 22 is annular and made in this example in one piece. Alternatively, the rings 21 and/or 22 can each be formed by two half-rings.

The inner ring 21 is integral with the shaft 9.

The outer ring 22 is intended to be connected to one of said casings of the turbojet engine 1, via a support 24.

In the example of Figure 2, the support 24 comprises an upstream axial part 25A, a downstream axial part 25B, a central radial flange 26A and a downstream radial flange 26B.

A shrunken ring 27 is tightly mounted in the upstream axial part 25A of the support 24 so as to extend radially between this upstream axial part 25 and the outer ring 22 of the bearing.

The bearing 20 further comprises a flexible cage 30 defining circumferentially spaced axial openings around the axis A1.

In this example, the cage 30 extends the outer ring 22 downstream and is made in one piece with this outer ring 22. In an embodiment not shown, the outer ring 22 and the cage 30 can form two parts. distinct assemblies with each other.

The cage 30 comprises a downstream end forming a radial flange 31 fixed to the radial flange 26B of the support 24.

The cage 30 is elastically deformable so as to allow a slight displacement in translation of the outer ring 22, in a plane orthogonal to the axis A1. The cage 30 thus performs a suspension function.

In this example, the outer ring 22 defines an outer surface 40 and includes five grooves 41A, 41B, 41C, 42A and 42B formed on this outer surface 40.

The grooves 41A and 41C are made at the upstream and downstream ends, respectively, of the ring 22. The groove 41B extends axially between the grooves 41A and 41C. Groove 42A extends axially between grooves 41A and 41B. The groove 42B extends axially between the grooves 41B and 41C.

Each of the grooves 41A-C and 42A-B forms an annular straight groove extending over the entire circumference of the ring 22, that is to say 360°.

Of course, the number of grooves and their geometry can be modified without departing from the scope of the invention. For example, in a variant embodiment not shown, the outer ring 22 includes the groove 42A but not the groove 42B, or vice versa.

The bearing 20 comprises three sealing members 44, 45 and 46 forming annular segments housed respectively in the grooves 41A, 41B and 41C.

The organs 44-46 establish a sealed connection with the shrink ring 27.

Shrink-fit ring 27 forms an inner surface 50, facing outer surface 40 of ring 22, so as to define, radially between these surfaces 40 and 50, an annular cavity 60.

The cavity 60 of FIG. 2 comprises in this example two adjacent compartments 60A and 60B which are axially contiguous.

More specifically, compartment 60A is delimited radially by surfaces 40 and 50 and axially by sealing members 44 and 45. Compartment 60B is delimited radially by surfaces 40 and 50 and axially by sealing members 45 and 46 .

Thus, in this example, the sealing member 45 delimits the compartment 60A axially downstream and the compartment 60B axially upstream.

The compartments 60A and 60B are therefore axially spaced from each other, in this case via the sealing member 45.

Compartment 60A has an axial dimension X1 less in this example than half the axial dimension X2 of compartment 60B.

The surfaces 40 and 50 being parallel in this example, the compartments 60A and 60B have an identical radial dimension X3.

In order to be able to introduce a fluid such as oil into the cavity 60, the shrunken ring 27 comprises one or more orifices 62A fluidly connecting the compartment 60A to a first annular groove 64A formed by the upstream axial part 25A of the support 24 and a or several orifices 62B fluidically connecting the compartment 60B to a second annular groove 64B formed by the upstream axial part 25A of the support 24.

Each of the grooves 64A and 64B is connected to a respective supply channel (not shown) configured to convey a respective oil-type fluid, or a respective part of an oil-type fluid, within the corresponding compartment 60A or 60B.

In an embodiment not shown, all or part of the orifices 62A and/or 62B can be connected to a supply channel directly, or indirectly via a groove or a notch made in the support 24 and having a different geometry from the grooves 64A and 64B described above.

The orifices 62A and 62B open respectively into the compartments 60A and 60B axially opposite the grooves 42A and 42B, respectively, formed by the ring 22. These grooves 42A and 42B make it possible to improve the circumferential distribution of the fluid introduced into these compartments 60A and 60B.

The introduction of oil into the compartments 60A and 60B of the cavity 60 thus makes it possible to form a double film of oil, known by the Anglo-Saxon name "squeeze-film", capable of radially damping a relative displacement of the ring outer 22 of the bearing with respect to the shrunken ring 27 and therefore with respect to the casing of the turbojet engine 1.

The double oil film corresponds in this example to a film in two contiguous sections delimited by the sealing member 45.

Such a bearing 20 makes it possible to differentially modulate the pressure and the flow of oil in each of the compartments 60A and 60B, using separate regulators (not shown) or alternatively using a single regulator (not represented).

In general, such a bearing 20 makes it possible to provide both a suspension function via the flexible cage 30 and a radial damping function via a double film of oil.

This radial damper makes it possible to dissipate part of the energy resulting from the orthogonal displacements authorized by the flexible cage 30 and to transmit the corresponding forces to the casing.

In this example, the surfaces 40 and 50, also called damping surfaces, are substantially cylindrical so that each of the compartments 60A and 60B of the cavity 60 is generally cylindrical.

In an embodiment not shown, the compartments 60A and/or 60B and/or at least one of the damping surfaces 40 and 50 can be conical.

In addition, the surfaces 40 and/or 50 may include machined parts so that the compartments 60A and 60B have a different radial dimension X3 relative to each other (not shown).

FIG. 3 illustrates an embodiment which differs from that of FIG. 2 in that the compartments 60A and 60B of the cavity 60 are not axially contiguous.

In what follows, Figure 3 is described mainly according to its differences with Figure 2. The description of Figure 2 above applies by analogy to the embodiment of Figure 3.

The outer ring 22 of the bearing 20 of Figure 3 comprises six grooves 41A, 41B1, 41B2, 41C, 42A and 42B formed on the outer surface 40. The grooves 41B1 and 41B2, similar to the groove 41B of Figure 2, are axially spaced from each other.

The bearing 20 comprises four sealing members 44, 45A, 45B and 46 housed respectively in the grooves 41A, 41B1, 41B2 and 41C.

In summary, the compartment 60A is delimited radially by the surfaces 40 and 50 and axially by the sealing members 44 and 45A. Compartment 60B is delimited radially by surfaces 40 and 50 and axially by sealing members 45B and 46.

Thus, in this example, the sealing member 45A axially delimits the compartment 60A downstream but does not axially delimit the compartment 60B upstream. The latter is delimited axially upstream by the sealing member 45B.

Similar to the embodiment of Figure 2, compartments 60A and 60B are axially spaced from each other. However, these are not contiguous in the embodiment of FIG. 3 since the sealing members 45A and 45B axially define between them a space X4.

As a result, the double oil film formed by the cavity 60 of the bearing 20 in FIG. 3 corresponds to a film in two non-contiguous sections.

The invention is in no way limited to the embodiments described above. For example, the compartments 60A and 60B may have a geometry and/or relative dimensions different from those illustrated in FIGS. 2 and 3, for example a non-axisymmetric geometry.

In addition, the cavity 60 can comprise more compartments which follow one another axially, contiguously or not.

Claims (10)

Bearing (20) for guiding a shaft (8, 9) of a rotating machine (1) in rotation about an axis (A1), comprising a first part (22) forming a rolling ring or being intended to be secured to a rolling ring of the bearing (20), and a second part (27) intended to be connected to a casing of the rotating machine (1), the first part (22) and the second part (27) defining radially between them a cavity (60) configured to receive at least one pressurized fluid so as to radially damp a relative displacement of the first part (22) with respect to the second part (27), characterized in that the cavity (60) comprises at least two compartments (60A, 60B) axially spaced from each other, a first of said compartments (60A) being configured to receive a first portion of the at least one fluid, a second of said compartments (60B) being configured to receive a second part of the at least one fluid. Bearing (20) according to claim 1, comprising a sealing member (45, 45A, 45B) arranged radially between the first part (22) and the second part (27) so as to axially delimit at least one of the compartments (60A, 60B). Bearing (20) according to Claim 2, in which the sealing member (45) delimits the first compartment (60A) axially downstream and the second compartment (60B) axially upstream. Bearing (20) according to Claim 2, in which the said sealing member forms a first sealing member (45A) axially delimiting the first compartment (60A) downstream, the bearing (20) comprising a second sealing member ( 45B) axially delimiting the second compartment (60B) upstream. Bearing (20) according to any one of claims 1 to 4, in which the second piece (27) comprises one or more first supply ports (62A) configured to introduce the at least one fluid into the first compartment (60A ) of the cavity (60) and one or more second supply ports (62B) configured to introduce the at least one fluid into the second compartment (60B) of the cavity (60). Bearing (20) according to claim 5, comprising at least one part (24) forming one or more supply ducts configured to convey the at least one fluid to the first and second compartments (60A, 60B) of the cavity (60 ) via the first and second supply ports (62A, 62B). A bearing (20) according to claim 6, wherein a first of said supply conduits is configured to convey the at least one fluid to the first compartment (60A) of the cavity (60) via the first supply port(s). (62A), and a second of said supply conduits is configured to convey the at least one fluid to the second compartment (60B) of the cavity (60) via the at least one second supply port (62B). Assembly comprising a bearing (20) according to any one of claims 1 to 7 and at least one pressure and/or flow regulator for the at least one fluid. Rotating machine (1) such as a turbomachine comprising a shaft (8, 9) and a bearing (20) according to any one of claims 1 to 7 for guiding the shaft (8, 9) in rotation around an axis (A1). Method for introducing at least one fluid into the compartments (60A, 60B) of the cavity (60) of a bearing (20) according to any one of Claims 1 to 7 and/or for pressure control and/or or in flow rate of the at least one fluid thus introduced.