Bearing housing with damping arrangement

A bearing housing for connecting a bearing to a supporting structure of a gas turbine engine is discussed. The bearing housing has an inner wall and an outer wall radially spaced apart from the inner wall between which an annular space is defined. A device extends from the inner wall toward the outer wall and includes at least a first and a second member in series between the inner and outer walls, the second member having a radial stiffness greater than a radial stiffness of the first member. The device may operate in multiple operating stages, where in a first stage the first member of the device deforms to absorb at least partially a vibration load over a given range of vibration amplitude when the bearing housing deflects, and where in a subsequent second stage the second member of the device increases a total radial stiffness of the assembly of the bearing housing and device over the bearing housing alone.

TECHNICAL FIELD

The application relates generally to bearing assemblies in a gas turbine engine and, more particularly, to bearing housings for bearings in a gas turbine engine.

BACKGROUND OF THE ART

Gas turbine engines typically include bearings to support one or more rotating shaft(s) (e.g. low-pressure compressor rotor, high-pressure compressor rotor, fan rotor) or one or more section(s) of one or more rotating shaft(s). However, known bearing assemblies, including bearing housings, may typically have limited capacity of reducing vibration transmission, for instance vibrations imparted by the rotating shaft(s) to the supporting structures of gas turbine engines via the bearing(s), such that this may limit performances of gas turbine engines.

SUMMARY

In one aspect, there is provided a bearing housing for a bearing in a gas turbine engine, the bearing housing comprising: an inner wall configured to support the bearing, and an outer wall radially spaced from the inner wall, an annular space being defined between the inner and outer walls; and a device extending from the inner wall toward the outer wall, the device including at least a first and a second member in series between the inner and outer walls, the second member having a radial stiffness greater than a radial stiffness of the first member.

In another aspect, there is provided a bearing housing for a bearing in a gas turbine engine, the bearing housing comprising: an inner shell configured to support the bearing; an outer shell disposed radially outwardly from and connected to the inner shell, the inner shell and the outer shell defining an annular space therebetween, the annular space having a radial dimension; and a snubber and a damper disposed in the annular space, the snubber having a stiffness greater than a stiffness of the damper, the damper configured to deform in use when the inner and outer shells move radially toward one another.

In a further aspect, there is provided a method for absorbing radial vibrations transmitted by a bearing to a bearing housing having inner and outer cylindrical walls defining between them an annular space, the method comprising: deforming a damper in the annular space and receiving at the damper a radial vibration load from the bearing; and then loading a snubber in the annular space having a stiffness greater than the damper to increase a radial stiffness of the bearing housing.

DETAILED DESCRIPTION

The gas turbine engine10also includes one or more rotating shaft(s) mounted thereto using mounting devices allowing rotational and/or axial movement, with two distinct shafts shown inFIG. 1. For instance, the compressor section14and the turbine section18may each have a single shaft or multiple independent shafts in parallel or in series, rotating dependently or independently, depending on the types of turbine engine, and mounted to the gas turbine engine10in many suitable ways.

Referring toFIG. 1, the mounting devices for mounting rotating shafts in the gas turbine engine10may be bearings20, such as ball bearings, roller bearings, thrust bearings, or any other suitable types of bearings. Also, there may have a combination of different types of bearings20inside the gas turbine engine10.

A bearing20in the gas turbine engine10is supported by a bearing housing30configured to receive the bearing20. An attenuation of vibration loads imparted by the rotating shafts or some components mounted thereon like the fan12(e.g. vibrations generated by the airflow inside or outside the engine) and transmitted via the bearing20to other components of the gas turbine engine10may be desirable. In the present case, the bearing housing30is configured to reduce (e.g. limit) vibration loads transmitted via the bearing20to other components of the gas turbine engine10. The bearing housing30includes a device40for absorbing at least partially vibration loads transmitted via the bearing20and for increasing a radial stiffness of the assembly of the bearing housing30and device40over the bearing housing30alone. Such device40may be used in combination or without the typical oil bearing damper (sometimes referred to as oil film damper) between the inner wall31and the outer race of the bearing20. Such oil film damper (not shown) is typically used to absorb vibration energies (e.g. caused by small rotor imbalances) and smaller vibration amplitudes.

FIGS. 2 to 4shows a particular embodiment of the bearing housing30comprising such device40. The bearing housing30includes an inner wall31configured to support a bearing20and an opposite outer wall32radially offset relative to the inner wall31. In an embodiment, the inner wall31may be defined as an inner shell and the outer wall32may be defined as an outer shell. An annular space33is defined between the inner wall31and the outer wall32. With additional reference toFIGS. 2 to 4, the annular space33has a radial dimension34. As it will be discussed later, the radial dimension34of the annular space33may vary upon radially loading the bearing housing30. In this particular embodiment, the inner wall31has an inner cylindrical surface for seating the bearing20and an outer cylindrical surface on which the device40may rest. A typical oil bearing damper (oil film damper) may be disposed between the inner wall31and the outer race of the bearing20. In an embodiment, the typical oil bearing damper may be disposed radially in line with the device40, although other arrangements are contemplated as well, such as with an offset. The outer wall32has an inner cylindrical surface configured to contact the device40. The inner wall31and the outer wall32may be implemented differently in other embodiments.

In some cases, such as in the embodiment ofFIG. 2, the inner wall31and the outer wall32are connected to one another via a wall35, in this case a hairpin-shaped wall. Such bearing housing configuration may be referred to as having a hairpin arrangement, with the name derived from the hairpin-like shape of the cross-section of the sequence of the structure32, the wall35and the inner wall31. The bearing housing30may have a different shape (e.g. no hairpin arrangement) in other particular embodiments. For instance, the wall35may be a straight wall instead of being a hairpin-shaped wall. Alternately, the inner wall31and the outer wall32may be interconnected to one another only by the device40connected to each one of the inner wall31and the outer wall32, without the wall35.

An allowable range of radial movement of the bearing20relative to other components of the gas turbine engine10may be desirable. To this end, in some cases, the inner wall31is connected to the outer wall32in cantilever fashion with one end of the inner wall31being free, such that the inner wall31in cantilever may vibrate relative to the outer wall32. In a particular case, the wall35connecting the inner wall31and the outer wall32may elastically deflect (radial deflection) to allow such vibrating movement between the inner wall31and the outer wall32. As such, the radial dimension34of the annular space33may vary, which permits an allowable range of radial movement of the bearing20relative to the outer wall32. The bearing housing30(with or without the device40) has a total radial stiffness Sh (i.e. radial stiffness of the bearing housing30as a whole) that allows it to radially elastically deform upon loading the bearing housing30with a radial load, in this case a radial vibration load VL.

The device40may absorb at least partially the radial vibration load VL transmitted via the bearing20and may vary the total radial stiffness Sh of the bearing housing30. In an embodiment, the device40is disposed in the annular space33of the bearing housing30and extends from the inner wall31toward the outer wall32. In an embodiment, the device40may extend from the inner wall and come in contact with the outer wall32upon the bearing20exceeding the allowable range of radial movement. However, the device40may contact the outer wall32permanently when installed in the bearing housing30(i.e. even with no vibration loads). The device40includes at least a first member41and a second member42. Referring toFIG. 4, the first member41and the second member42are disposed on one another (i.e. the first member41and the second member42are in series) between the inner wall31and the outer wall32. The first and second members41,42may be directly disposed on one another or may have another member in between them. The first and second members41,42may also be connected together in many suitable ways, including by bonding, molding, and overmolding. The first and second members41,42may also be mechanically interlocked (i.e. they may be shaped such that they may mechanically interlock to one another).

In an embodiment, the second member42is disposed directly over the outer cylindrical surface of the inner wall31such that the second member42directly contacts the inner wall31. The second member42may be bonded to the inner wall31using an adhesive, mounted on the inner wall31in a tight fit (i.e. tight fit or press fit) fashion, welded to it, etc. In other embodiments, the relative position of the members may be different. For instance, the first and second members41,42may be disposed inversely, such that the second member42may be disposed along the inner cylindrical surface of the outer wall32and the first member41may be disposed radially inwardly therefrom.

The first and second members41,42may have many suitable shapes. For instance, in an embodiment, the first member41, sometimes referred to as a damper or spring-damper, is annular (e.g. a ring shape) and extends circumferentially along the second member42, inside the annular space33. In an embodiment, the second member42, sometimes referred to as a snubber, has a continuous annular shape and extends circumferentially along the inner wall31of the bearing housing30inside the annular space33. As shown inFIG. 3, in this particular embodiment, the second member42may have an hollowed-out body with a plurality of radially elongated members (e.g. spokes). This may reduce the weight of the second member42and in turn of the device40as a whole. At its periphery, the second member42may have a peripheral recess in the form of an annular channel in which the first member41may be received at least partially, though this is only an option as the second member42may have no such annular channel. As such, when received in the annular channel, a portion of the first member41may extend radially in parallel to the second member42between the inner and outer walls31,32. As observed fromFIG. 4, the side walls of the annular channel may define abutments that limit transversal expansion of the first member41when deforming as a result of a compressive load VL in the radial direction. A radial gap43may be defined between the second member42and one of the inner and outer walls31,32, where the radial gap43inFIG. 4is shown radially between said side walls and the outer wall32. In other embodiments, the first and second members41,42may be shaped differently. For instance, the first member41may not have a ring shape. The first member41may be discontinuous (e.g. segmented in a plurality of distinct pieces disposed on the second member42). Also, in other embodiments, the second member42may not have a continuous annular shape and/or may not have a hollowed-out body. For instance, in some cases, the second member42may be discontinuous (e.g. segmented in a plurality of pieces disposed peripherally along the inner wall31). This is visible in the example shown inFIGS. 3A and 3B. As shown, the segments of the second member42′ may be connected to adjacent ones of the segments by interfaces46′. More specifically, in the example shown, the interfaces46′ takes the form of one or more layer of polymeric material adhered to (or otherwise connected to) adjacent segments in between them. In this configuration, since the polymeric material may elastically deform due to its inherent viscoelastic characteristics (e.g. compressed), they may allow small tangential motions between the segments of the second member42′. This may further provide damping of vibrations by the damping device40′. Other types of interfaces46′ may allow such circumferential motions between the segments of the second member42′ in other variants, such as coils springs. In this example, the first member41′ is segmented in a plurality of distinct pieces and disposed on the segments of the second member42′. Each segments of the first member41′ may be disposed on a respective one of the segments of the second member42′, such as shown, although this may not be the case in other variants. For instance, segments of the first member41′ may extend over two or more adjacent ones of the segments of the second member42′, in some cases. Also, in some cases, the second member (42,42′) may have a solid-body shape (i.e. not hollowed-out).

In this particular embodiment, the second member42is radially thicker than the first member41. That is, a radial dimension44of the first member41is smaller than a radial dimension45of the second member42in a radial direction. This may be different in other embodiments.

The second member42may be stiffer (e.g. slightly or substantially stiffer) than the first member41. That is, the second member42may be harder to compress or stretch than the first member41. In this particular embodiment, the first member41has a stiffness S1and the second member has a stiffness S2. The stiffness S2is substantially greater than the stiffness S1. In some embodiments, the stiffness S1, S2of the first and second members41,42may be measured as a compressive strength, a tensile strength, or a modulus of elasticity (e.g. Young's modulus). In other embodiments, the first member41may be stiffer than the second member42.

The first member41and the second member42may be made of any suitable material. For instance, in some cases, the first member41is made at least in part of a viscoelastically deformable material. More particularly, in some cases, the first member41is made at least in part of an elastomeric material (e.g. rubber). In some cases, the first member41is made of a lattice structure, such as a metal foam. Other materials with viscoelastic properties may be used. Viscoelastic materials may absorb energy/loads when deformed (i.e. they may damp/dissipate energy/load). The first member41may be selected to deform elastically over a distance, which corresponds to the radial gap43inFIG. 4, when exposed to a compressive force. As for the second member42, in some cases, it may be made at least in part of a rigid material (i.e. not a viscoelastic material), such as a metal alloy, a titanium alloy, an aluminium alloy, or a composite material such as a fiber-reinforced material. Rigid materials may contribute to increasing the overall stiffness of the device40and in turn the total radial stiffness Sh of the bearing housing30, as discussed later. Other suitable materials may be used.

A deformation of the device40may occur when the radial dimension34of the annular space33varies. In some cases, where the device40does not contact the outer wall32permanently when installed in the bearing housing30, as discussed above, such deformation only occurs once the device40contacts the outer wall32. As such, an initial slight radial movement of the bearing20may occur (e.g. because of the compression of the oil film damper, if present) without starting to deform the device40. As discussed above, the radial dimension34of the annular space33may vary upon radially loading the bearing housing30. As the radial dimension34of the annular space33is being reduced, the device40is squeezed (i.e. compressed) between the inner wall31and the outer wall32. In this particular embodiment, since the stiffness S2of the second member42is substantially greater than the stiffness S1of the first member41, the first member41may deform to absorb at least partially the radial vibration load VL, while the second member42remains non-deformed (i.e. at least substantially non-deformed). Stated differently, the radial dimension45of the second member42remains substantially invariable while the first member41is being deformed and the device40compressed between the inner wall31and the outer wall32. Stated differently, a differential between the radial dimension45of the second member42and the radial dimension34of the annular space33varies (i.e. reduces) and the radial dimension45of the second member42remains substantially constant while the first member41is being deformed.

The device40may operate in multiple operating stages (e.g. serial operating stages). For instance, in this particular embodiment, a first operating stage corresponds to a variation of the radial dimension44of the first member41over a variation of the radial dimension34of the annular space33upon radially loading the bearing housing30. In the first operating stage, a ratio of the variation of the radial dimension44of the first member41over the variation of the radial dimension34of the annular space33is at least 0.95. Stated differently, in the first operating stage, at least 95% of the decrease of the radial dimension34results from the deformation of the first member41, and consequently by a decrease in radial dimension44. In the first operating stage, the gap43, which corresponds in this case to a differential between the radial dimension45of the second member42and the radial dimension34of the annular space33, decreases until it is fully suppressed. Thus, in this particular embodiment, in the first operating stage, the radial dimension34of the annular space33reduces while the first member41deforms to absorb at least partially the radial vibration load VL transmitted to the bearing housing30via the bearing20until the gap43is fully suppressed (i.e. the differential between the radial dimension45of the second member42and the radial dimension34of the annular space33stops varying). Alternatively, the gap43, again corresponding to a differential between the radial dimension45of the second member42and the radial dimension34of the annular space33, decreases until the first member41resists to further deformation. These scenarios may occur in cases of more substantial rotor imbalance that could not be fully compensated by an oil film damper. For example, more substantial rotor imbalances may be caused by foreign objects ingested in the engine (e.g. small birds, hail, icing condition, etc.). When these scenarios occur, the device40transitions to a second operating stage.

As discussed above, the device40, as part of the bearing housing30, is configured to increase the total radial stiffness Sh of the bearing housing30, in contrast to a bearing housing without a device40. To this end, in an embodiment, in the second operating stage, the second member42is configured to increase the total radial stiffness Sh of the bearing housing30after the gap43is fully suppressed or when the combination of the compressed first member41and the second member42oppose a resistance preventing further substantial deformation, whereby the gap43no longer decreases. The gap43may be selected to permit the allowable range of radial movement of the bearing20. Consequently, in this embodiment, as long as the gap43is present, the bearing may move radially relative to the outer wall32, and in contrast, when the gap43is fully suppressed, the second member42bridges the inner wall31and the outer wall32, whereby the device40prevents any further radial movement of the bearing20exceeding the allowable range of radial movement of the bearing20. In an embodiment, when the gap43is fully suppressed, the first member41fully recedes in the peripheral recess defined in the second member42, and thus the second member42contacts both the inner wall31and the outer wall32. The second member42thus implements a rigidifying member (e.g. internal rib) interconnecting the inner wall31and the outer wall32of the bearing housing30, thereby radially rigidifying the bearing housing30. As understood from above, the rigidifying member may be embodied by the compressed first member41and the second member42.

FIGS. 5 to 8show another particular embodiment of the bearing housing30and the device for absorbing at least partially vibration loads transmitted via the bearing20and for varying a total radial stiffness of the bearing housing30. With reference to this particular embodiment, there is provided a bearing housing30′ that comprises an inner wall31′ configured to connect to a bearing20′ and an outer wall32′ disposed radially outwardly from and connected to the inner wall31′. An annular space33′ is defined between the inner wall31′ and the outer wall32′. The annular space33′ has a radial dimension34′ and the bearing housing30′ has a total radial stiffness Sh′. Similarly to an embodiment discussed above, the inner wall31′ and the outer wall32′ are configured to allow a relative radial movement therebetween. As such, the radial dimension34′ of the annular space33′ may vary upon radially loading the bearing housing30, which permits an allowable range of radial movement of the bearing20′ relative to the outer wall32′.

In this particular embodiment, a device50is part of the bearing housing30′ and disposed in the annular space33′ and is configured to absorb at least partially a radial vibration load VL′ and to increase the total radial stiffness Sh′ of the bearing housing30′.

The device50includes one or more bodies spaced apart and disposed circumferentially between the inner wall31′ and the outer wall32′ of the bearing housing30′. In this particular embodiment, each one of the plurality of bodies includes a plurality of members disposed on one another, for instance in the form of layers or as layered over one another (i.e. layers in series).

One or more of the members of the plurality of members may be configured to absorb at least partially the radial vibration load VL′ and/or configured to contribute to increasing the total radial stiffness Sh′ of the bearing housing30′, as discussed below.

More particularly, in an embodiment, at least one of the bodies of the device50includes a first member51, a second member52, a third member53, a fourth member54and a fifth member55disposed in series on one another. There may be as little as two members in an embodiment corresponding to the embodiment illustrated inFIG. 4described above, but also more than the five members as illustrated inFIG. 8. These members51,52,53,54,55may be connected to one another in any suitable ways, including adhesively bonding, comolding, high-frequency molding, mechanical interlocking, etc. One or more of the members51,52,53,54,55may be made at least in part of a viscoelastically deformable material (e.g. an elastomeric material, such as rubber, or a lattice structure, such as a metal foam). One or more of the members51,52,53,54,55may additionally or alternately be made at least in part of a rigid material, such as a metal alloy, a titanium alloy, an aluminium alloy, a composite material such as a fiber-reinforced material, or other relatively rigid material. The bodies of the device50resulting from stacking these members51,52,53,54,55may each absorb partially the radial vibration load VL′ and/or contribute to increasing the total radial stiffness Sh′ of the bearing housing30′ as they become part of the bearing housing30′.

In an embodiment, the first, third and fifth members51,53,55are each made at least in part of an elastomeric material and are spaced apart from one another by the second and fourth members52,54, which are each made at least in part of a rigid material in the form of a layer. Having layers of rigid material interleaved between members of elastomeric materials (or lattice structure, such as metal foam) may allow the different viscoelastically deformable members51,53,55to better be secured to one another, and/or contribute to the structural integrity of the device50while it deforms during operation (e.g. the rigid layers may limit transversal deformation of the viscoelastic members implementing each one of the bodies when compressed, as the rigid layers may not stretch or not otherwise deform substantially when the bodies are compressed). Also, having rigid members such as the second and fourth members52,54may contribute to rigidifying the device50and in turn increasing the total radial stiffness Sh′ of the bearing housing30′.

Each one of the members51,52,53,54,55may or may not have different dimensions (e.g. radial dimension, transversal dimension, etc.), and/or a different stiffness. As such, the members51,52,53,54,55may react differently when subjected to the radial vibration load VL′ transmitted from the bearing housing30′ to the device50.

In an embodiment, as discussed above, the second and fourth members52,54are made at least in part of a rigid material, each in the form of a layer of rigid material. When subjected to the radial vibration load VL′, the second and fourth members52,54remain non-deformed (i.e. at least substantially non-deformed) due to their low transversal expansion, low radial compression and/or stiffness, while the device50is being compressed. Thus, their respective radial dimensions remain substantially invariable when the device50is subjected to the radial vibration load VL′.

In this particular embodiment, the first, third and fifth members51,53,55, which are in this case viscoelastic members, may each deform to a certain extent when the radial dimension34′ of the annular space33′ is being reduced and the device50squeezed (i.e. compressed), and they may each absorb at least partially the radial vibration load VL′. In an embodiment, the first member51may be more deformable than the third member53, which may be more deformable than the fifth member55when subjected to the radial vibration load VL′. This may be due to different properties of each one of the first, third and fifth members51,53,55, including, for instance, their respective dimensions (e.g. radial dimensions, transversal dimensions), stiffness, other material properties, or a combination thereof.

In an embodiment, a radial dimension56(i.e. thickness) of the first member51is smaller than a radial dimension58(i.e. thickness) of the fifth member55, which is smaller than a radial dimension57(i.e. thickness) of the third member53. Also, in this particular embodiment, the first member51is transversally larger than the third member53, which is transversally larger than the fifth member55.

In this particular embodiment, the fifth member55is stiffer than the third member53, which is stiffer than the first member51. That is, a radial stiffness E5of the fifth member55is substantially greater than a radial stiffness E3of the third member53, and the radial stiffness E3is greater than a radial stiffness E1of the first member51. That is, the bodies of the device50are arranged such that they have a radially outwardly decreasing stiffness. This may be different in other embodiments.

This particular combination of members with the properties discussed above, including their respective stiffness, dimensions and relative position may be different in other embodiments. For instance, there may not be rigid members/layers between adjacent viscoelastic members, the members may be reordered such as to obtain a body with a radially outwardly increasing stiffness (as opposed to the embodiment ofFIG. 5), and/or their respective radial or transversal dimensions may be different.

Combining a plurality of members with different stiffness, dimensions, and/or damping properties may improve damping capabilities of the device50when subjected to the radial vibration load VL′. For instance, this may allow a plurality of cumulative operating stages (e.g. cumulative stages allowing a progressively increasing stiffness of the bearing housing30′ over given ranges of vibration amplitudes). In an embodiment, the device50has three operating stages, in which the device50may absorb at least partially the radial vibration load VL′ and progressively increase the total radial stiffness Sh′ of the bearing housing30′. In an embodiment, in each operating stage, each one of the first, third and fifth members51,53,55may deform to absorb at least partially the radial vibration load VL′ transmitted to the bearing housing30′ via the bearing20′ to a certain extent. In a first operating stage, over a first vibration amplitude range, a ratio of a variation of the radial dimension56of the first member51over a variation of the radial dimension34′ of the annular space33′ is at least 0.95, a ratio of a variation the radial dimension57of the third member53over the variation of the radial dimension34′ of the annular space33′ is no more than 0.04, and a ratio of a variation the radial dimension58of the fifth member55over the variation of the radial dimension34′ of the annular space33′ is no more than 0.01. In a second operating stage, over a second vibration amplitude range where the vibration amplitudes become greater than the first vibration amplitude range, the ratio of the variation of the radial dimension56of the first member51over the variation of the radial dimension34′ of the annular space33′ is no more than 0.85, the ratio of the variation the radial dimension57of the third member53over the variation of the radial dimension34′ of the annular space33′ is at least 0.13, and the ratio of the variation the radial dimension58of the fifth member55over the variation of the radial dimension34′ of the annular space33′ is no more than 0.02. Finally, in a third operating stage, over a third vibration amplitude range where the vibration amplitudes become greater than the second vibration amplitude range, the ratio of the variation of the radial dimension56of the first member51over the variation of the radial dimension34′ of the annular space33′ is no more than 0.8, the ratio of the variation the radial dimension57of the third member53over the variation of the radial dimension34′ of the annular space33′ is at no more than 0.15, and the ratio of the variation the radial dimension58of the fifth member55over the variation of the radial dimension34′ of the annular space33′ is at least 0.05. In other embodiments, the above ratios may be different, depending on the damping capabilities and the cumulative operating stages of the device50.

A method for absorbing radial vibrations transmitted by a bearing20to a bearing housing30,30′ is also provided. In a particular embodiment, the method comprises deforming a first member (e.g.41,51) of the device (e.g.40,50) upon a reduction of a radial dimension of the annular space (e.g.33,33′) while receiving a radial vibration load VL via the bearing20to absorb at least partially the radial vibration load VL over a given range of vibration amplitude in a first operating stage. The device transitions subsequently from that first operating stage to a second operating stage in which a second member (e.g.42,53) having a stiffness S2greater than that of the first member is abutted between the inner wall (e.g.31,31′) and outer wall (e.g.32,32′) when the range of vibration amplitude is exceeded. In this second operating stage, the total radial stiffness Sh of the bearing housing (e.g.30,30′) is increased, as discussed above with respect to some embodiments.

In a particular embodiment, the disclosed bearing housing30may help reducing significantly the vibrations of the gas turbine engine10as a whole, reducing fan tip clearance loss, and/or reducing (e.g. reducing or in some cases avoiding) low-pressure boost rubbing.

In an embodiment, the bearing housing30with the device40may provide a reduction of at least 20% of the fan12deflection over the fan12deflection with a bearing housing30without such device40.