FR3095242A1 - TURBOMACHINE MODULE EQUIPPED WITH A DAMPING DEVICE FOR TURBOMACHINE GUIDE BEARING - Google Patents

Abstract

TURBOMACHINE MODULE EQUIPPED WITH A DAMPING DEVICE FOR TURBOMACHINE GUIDE BEARING The invention relates to a turbomachine module comprising: a rotary shaft with a longitudinal axis X; a rotating guide bearing of the rotary shaft about the longitudinal axis X and comprising an internal ring integral in rotation with the rotary shaft; and a damping device arranged around the guide bearing, the damping device comprising an outer ring (14) surrounding the inner ring and a support ring (23) mounted at a radial distance around the outer ring (14) so as to form a damping chamber (20), the damping chamber (20) being at least partially delimited axially by sealing elements (24) and being intended to receive a fluid damping film (19) ), the sealing elements (24) being arranged so as to form a radial passage (36) with the support ring so as to allow the leakage of the fluid damping film from the damping chamber. According to the invention, the sealing elements (24) are deformable so as to increase or reduce the section of the passage of the fluid damping film. Figure for the abstract: Figure 5

Description

TURBOMACHINE MODULE EQUIPPED WITH DAMPING DEVICE FOR TURBOMACHINE GUIDE BEARING

Field of invention

The present invention relates to the general field of aeronautics and in particular to damping devices for turbine engine rotating members.

Technical background

In general, a turbomachine comprises rotating members such as shafts which are guided by guide bearings with respect to a fixed structure of the turbomachine. These guide bearings comprise an inner ring and an outer ring enclosing rolling elements, for example rollers or balls. Conventionally, the outer ring is mounted integrally on a fixed structure of the turbomachine and the inner ring is mounted integrally on the rotating shaft of the turbomachine.

Certain guide bearings may comprise a fluid damping film more or less imprisoned in a damping chamber so as to damp the movements of the rotating shafts and to reduce the vibrations of the latter which are transmitted to the fixed structures of the turbomachine and to the aircraft. The damping fluid film is known by the English designation “squeeze film damper” to improve the dynamic response of the turbomachine at a given operating speed and consequently the performance of the turbomachine. The damping chamber is delimited on the one hand, radially between the outer ring of the guide bearing (which is locked in rotation) and the fixed structure of the turbomachine and on the other hand, axially by sealing elements.

The damping provided by the damping fluid film depends on several parameters such as the leakage rate, the viscance, the temperature, etc. The management of the leakage rate is particularly complex because the inlet pressure of the fluid in the damping chamber varies according to the speed of the turbomachine while the temperature of the fluid changes naturally according to the speed of the turbomachine, the time of operation of the turbomachine and the relative movement between the outer ring and the fixed structure. For example, the supply temperature of the damping fluid film is greater at high speed (aircraft take-off phase) whereas the temperature of the damping fluid film is low at low speed. The temperature of the fluid damping film influences its viscance so that at a low temperature (for example of the order of 90° C.), the fluid damping film is very viscous (for example of 5.10 ⁴ kg/s) and at a higher temperature (for example 140° C.), the damping fluid film is less viscous (for example 2.5.10 ⁴ kg/s). The damping is therefore not optimal for reducing the amplitudes of vibrations according to the speeds.

It is expected that when the temperature and the pressure of the damping fluid film increase, the sealing elements allow the “leakage” of the damping fluid film towards the damping fluid supply circuit and/or towards the enclosure in which the guide bearings are installed. However, sealing elements that are not sized correctly can impact the dynamic behavior of the turbomachine and lead to a lack of damping of the vibration modes which can lead to premature failure of the parts and organs of the turbomachine. Indeed, with the rise in temperature, parts (outer ring, sealing elements, etc.) in contact with the damping fluid film expand. Differential expansion between parts can be significant depending on part geometry and materials used. The expansion of the sealing elements is such that leakage of the damping fluid film is made difficult and decreases. Since the fluid can be trapped in the damping chamber, its temperature also increases (effect of the relative displacement between the rings and the fixed structure). This further reduces leakage and therefore causes the temperature to rise until the damping chamber is completely sealed. The guide bearing is not damped, the ring and the fixed structure abut against each other, which increases the load in the bearing significantly and then leads to early failure of the bearing.

The objective of the present invention is to provide an optimized damping device making it possible to control the leakage rate of the damping fluid film.

We achieve this objective in accordance with the invention thanks to a turbomachine module comprising:

• a rotary shaft with longitudinal axis X;
• a bearing for guiding the rotary shaft in rotation around the longitudinal axis X and comprising an inner ring (13) integral in rotation with the rotary shaft; and
• damping device arranged around the guide bearing, the damping device comprising an outer ring surrounding the inner ring and a support ring mounted at a radial distance around the outer ring so as to form a damping chamber, the damping chamber being at least partly delimited axially by sealing elements and being intended to receive a fluid damping film, the sealing elements being arranged so as to form a radial passage with the support ring of so as to allow the fluid film of damping oil to escape from the damping chamber, the sealing elements being deformable so as to increase or reduce the section of the passage of the fluid damping film.

Thus, this solution achieves the above objective. In particular, the deformable sealing elements make it possible to regulate the leakage rate in the damping chamber in a simple and economical way, which makes it possible to reduce the pressure of the damping fluid in the damping chamber. This maintains the performance of the damping device as well as that of the turbomachine. Such a configuration also makes it possible to control the temperature of the damping fluid film in the damping chamber.

The turbomachinery module also includes one or more of the following features, taken alone or in combination:

• the sealing elements are made of a shape memory material.
• the sealing elements are deformable at a temperature greater than or equal to a threshold temperature value.
• the sealing elements include first and second annular segments.
• the support ring comprises a supply orifice opening into the damping chamber, the first and second segments being respectively arranged on either side axially of the supply orifice.
• the sealing elements are made of a metal alloy.
• the metal alloy includes Copper, Aluminum and Nickel.
• the threshold temperature value is between 50°C and 200°C.
• the inner ring and the outer ring respectively comprise an inner surface which form inner rolling tracks for rolling elements arranged radially between the inner ring and the outer ring.

The invention further relates to a turbomachine comprising at least one turbomachine module having any one of the preceding characteristics.

Brief description of figures

The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

FIG. 1 is a view in axial and partial section of an example of a turbomachine to which the invention applies;

FIG. 2 is a view in radial section of an example of a bearing for guiding in rotation a rotary member such as a shaft of a turbomachine in a turbomachine module according to the invention;

FIG. 3 is a perspective view of an example of a sealing element of a damping device for a rotary member according to the invention;

Figure 4 is a schematic view and in axial section of the sealing elements installed in a damping chamber and in a first position according to the invention; and

Figure 5 schematically illustrates the sealing elements of Figure 4 in a second position according to the invention.

Detailed description of the invention

FIG. 1 shows a view in axial and partial section of a turbomachine with longitudinal axis X to which the invention applies. The turbine engine shown is a dual-flow turbine engine 1 intended to be mounted on an aircraft. Of course, the invention is not limited to this type of turbomachine.

Conventionally, the turbomachine comprises a rotary shaft which is guided in rotation via one or more guide bearings with respect to a fixed part of the turbomachine. The rotating shaft may be a low pressure shaft of the turbomachine. The rotary shaft can also be a high-pressure shaft or any shaft driven in rotation by means of a guide bearing within the turbomachine.

Referring to Figure 1, the low pressure shaft 2 drives for example a fan 3 arranged upstream of the turbomachine. The turbomachine 1 comprises downstream of the fan and successively, a compressor assembly (low pressure compressor 4a and high pressure compressor 4b), a combustion chamber 5 and a turbine assembly (high pressure turbine 6a and low pressure turbine 6b) which form a gas generator.

In the present invention, the terms “upstream” and “downstream” are defined with respect to the circulation of gases in the turbomachine and here along the longitudinal axis X.

The low pressure shaft 2 connects the low pressure compressor of the compressor assembly and the low pressure turbine of the turbine assembly to form a low pressure body. The turbomachine 1 can also comprise a high pressure body which comprises the high pressure compressor of the compressor assembly connecting the high pressure turbine of the turbine assembly via a high pressure shaft.

The rotary shaft, here the low pressure shaft 2, is centered on the longitudinal axis X. The low pressure shaft 2 is guided at its upstream end by an upstream guide bearing 10 and at its downstream end by a bearing of guidance 11 downstream. The guide bearings 10, 11 are each housed in an enclosure of a fixed casing 12 relative to which the low pressure shaft 2 rotates.

With reference to FIG. 2 showing a turbomachine module, each bearing 10, 11 comprises an annular inner ring 13 mounted on the rotary shaft (low-pressure shaft 2) and an annular outer ring 14 connected to a fixed structure integral with the casing. stationary of the turbomachine. The inner ring 13 is shrunk on the low pressure shaft 2 so as to prevent any translation and any rotation of the inner ring relative to the low pressure shaft. The outer ring 14 is advantageously fixed to the fixed structure using an anti-rotation device to lock it in rotation relative thereto. The anti-rotation device is generally formed of a radial spacer 15 which is housed, on the one hand in a notch of the outer ring 14 which opens to the outside, and on the other hand in a hole (not shown) of the fixed structure secured to the fixed casing 12. The outer ring 14 surrounds and is arranged at a radial distance from the inner ring 13.

In the present invention, the terms "radial" and "radially" are defined with respect to a radial axis R perpendicular to the longitudinal axis X.

Between the inner and outer rings 13, 14 are arranged rolling elements 16 such as rollers or balls which ensure the link between the rotary shaft and the fixed structure of the turbomachine. The inner and outer rings 13, 14 include inner surfaces 17, 18 which form inner raceways for the rolling elements 16.

In Figure 2 we also see that the bearing 10, 11 is equipped with a damping device. The latter comprises a damping fluid film 19 which circulates between the outer ring 14 and the fixed structure of the turbomachine. This damping fluid film 19 makes it possible to limit, dampen or even regulate the vibrations of the turbomachine 1 in operation. Indeed, the turbomachine is known to vibrate according to at least one given vibration mode during the rotation of one or more rotating shaft(s). These vibrations are due, for example, to balancing faults in the turbomachine and unbalances generated as a result of these balancing faults.

The damping fluid film 19 is designed to occupy an annular damping chamber 20. The latter is located radially between the outer ring 14 of the guide bearing and here a support ring 23 or annular outer intermediate ring. The support ring 23 is fixed to the fixed structure of the fixed casing 12. In other words, the support ring 23 surrounds the outer ring 14 of the bearing 10, 11 and is also placed at a radial distance from it. this.

Each annular damping chamber 20 is delimited radially by the support ring 23 and the outer ring 14. In particular, the supply fluid film circulates at the level of a radially inner surface 21 of the outer ring and of a radially outer surface 22 of the support ring. These radially inner and outer surfaces are spaced radially from each other.

Each damping chamber 20 is also delimited at least in part axially by sealing elements 24 which regulate or authorize the “leaks” of damping film fluid towards the outside of the damping chamber. These control the leakage rate of the damping fluid film in order to ensure effective vibration damping. In the present invention, the terms "axial" and "axially" are defined with respect to the longitudinal axis X.

In FIGS. 4 and 5, the sealing elements 24 comprise a first annular segment 26 and a second annular segment 27 which extend radially into the damping chamber 20. The segments 26, 27 extend radially between the ring outer ring 14 and the support ring 23. The outer ring 14 comprises a first annular groove 28 and a second annular groove 29 each intended to house at least partially a segment 26, 27. The first and second grooves 28, 29 are formed respectively at the level of the radially inner surface 21 of the outer ring 14 and are arranged axially at a distance from each other. The segments extend radially from their groove and face support ring 23.

As we can see in Figure 3, each first segment and second segment is split. These each include an opening 30 which forms ends 31 facing each other. Each end 31 is defined in a plane which is parallel to an RX plane. The RX plane is formed by the longitudinal X and radial R axes. The segments have a general rectangular section.

According to another alternative embodiment not illustrated, each first segment and second segment is split and is of the bayonet type. In this case, each end 31 comprises a tongue extending in a circumferential direction (transverse axis T). The transverse axis T is perpendicular to the longitudinal X and radial R axes. The two tongues each have a surface intended to bear against each other and an axially opposite surface which is flush with one side of the segment.

The first and second segments can also be provided with notches on an outer peripheral edge 37 which is annular. The latter is located at a radial distance from the radially outer surface 22 of the support ring 23. These notches are regularly distributed around the axis of the segment (parallel to the longitudinal axis X in the installation situation). In this exemplary embodiment, the notches make it possible to evacuate the power dissipated by damping in the fluid damping film.

The turbomachine 1 is also equipped with a supply system comprising a supply circuit 32 which is connected to a supply source (not shown) so as to supply at least the damping fluid film. The damping fluid film here is an oil which is under pressure. The supply system can also supply oil to the rotating guide bearings for lubrication.

In FIGS. 4 and 5, the support ring 23 of each guide bearing comprises a supply orifice 35 which opens into the damping chamber and which is coupled to the supply circuit. The sealing rings 26, 27 are arranged on either side axially of the feed orifice 35.

As we can also see in Figures 4 and 5, the sealing rings 26, 27 are arranged so as to provide a radial passage 36 with the support ring 23 so as to allow the damping fluid film to escape. of the damping chamber 20. The damping fluid film returns, for example, to the supply circuit and/or to the enclosure in which at least one bearing is arranged.

The sealing elements 26, 27 are configured so as to occupy a first position in which the passage 36 has a first section S1 which is minimum and which allows the leakage of a minimum flow rate of damping fluid film and a second position in which the passage has a second section S2 which is maximum and which allows a maximum leakage rate. We therefore understand that in the second position, the section S2 of the passage 36 is greater than the section S1 in the first position.

The first and second segments 26, 27 are deformable so as to increase or reduce the section of the radial passage of the damping fluid film. This configuration is very simple to implement and is economical. This allows in particular not to make substantial modifications to the parts of the damping device such as the outer ring, the support ring, nor to add in this case a servo system.

Advantageously, the segments 26, 27 are made of a shape-memory or reversible material.

In the present exemplary embodiment, the temperature makes it possible to control the change in shape of the first and second segments 26, 27. In particular, the sealing segments deform when the temperature of the damping fluid, here oil, in the damping chamber, is equal to or greater than a threshold temperature value. Here, the sealing rings bend to enlarge the section of the passage (section S2) at this threshold temperature value and return to their initial shape (section S1) when the temperature is lower than this value. The threshold temperature value is between 50°C and 200°C.

The segments are made of a metal alloy. An example of a metal alloy is a mixture of Copper, Aluminum and Nickel. The threshold temperature value of this alloy is between 80°C and 200°C depending on the concentration of the compounds.

We obtain with such deformable and shape-memory sealing rings a robust damping device. Damping is effective by controlling the pressure and temperature of the damping fluid film in the damping chamber.

Claims (10)

Turbomachine module comprising:

• a rotary shaft (2) of longitudinal axis X;
• a guide bearing (10, 11) in rotation of the rotary shaft around the longitudinal axis X and comprising an inner ring (13) integral in rotation with the rotary shaft; and ,
• a damping device arranged around the guide bearing, the damping device comprising an outer ring (14) surrounding the inner ring (13) and a support ring (23) mounted at a radial distance around the outer ring ( 14) so as to form a damping chamber (20), the damping chamber (20) being at least partly axially delimited by sealing elements (24) and being intended to receive a damping fluid film (19), the sealing elements (24) being arranged so as to form a radial passage (36) with the support ring so as to allow leakage of the damping fluid film from the damping chamber (20 ), characterized in that the sealing elements (24) are deformable so as to increase or reduce the section of the passage (36) of the damping fluid film.

Turbomachine module according to the preceding claim, characterized in that the sealing elements (24) are made of a material with shape memory. Turbomachine module according to any one of the preceding claims, characterized in that the sealing elements (24) are deformable at a temperature greater than or equal to a threshold temperature value. Turbomachine module according to any one of the preceding claims, characterized in that the sealing elements (24) comprise first and second annular segments (26, 27). Turbomachine module according to the preceding claim, characterized in that the support ring (23) comprises a supply orifice (35) opening into the damping chamber (20), the first and second segments (26, 27) being respectively arranged on either side axially of the feed orifice (35). Turbomachine module according to any one of the preceding claims, characterized in that the sealing elements (24) are made of a metal alloy. Turbomachine module according to the preceding claim, characterized in that the metal alloy comprises copper, aluminum and nickel. Turbomachine module according to any one of Claims 3 to 7, characterized in that the threshold temperature value is between 50°C and 200°C. Turbomachine module according to any one of the preceding claims, characterized in that the inner ring and the outer ring respectively comprise an inner surface (17, 18) which form internal tracks for rolling elements (16) arranged radially between the ring inner (13) and the outer ring (14). Turbomachine (1) comprising at least one turbomachine module according to any one of the preceding claims.