WO2022043123A1

WO2022043123A1 - Slide bearing device, transmission device comprising a slide bearing device, and gas turbine engine comprising a slide bearing device

Info

Publication number: WO2022043123A1
Application number: PCT/EP2021/072789
Authority: WO
Inventors: Greg Blake; Michael Gräber
Original assignee: Rolls-Royce Deutschland Ltd & Co Kg
Priority date: 2020-08-28
Filing date: 2021-08-17
Publication date: 2022-03-03
Also published as: DE102020122564A1

Abstract

The invention relates to a slide bearing device (50) comprising a lubrication film between sliding surfaces (51, 52) and comprising at least one particle transport channel (60) in at least one sliding surface (51, 52) of the slide bearing device (50), wherein the direction of the at least one particle transport channel (60) has • · an angle (a) not equaling 90° relative to a plane perpendicular to the rotational direction (R) at least in some sections in the case of a radial slide bearing device (50) and • · an angle (a) not equaling 0° relative to a cylindrical surface about the rotational direction (R) at least in some sections in the case of an axial slide bearing device (50), the at least one particle transport channel (60) fluidically contacts at least one particle reservoir (61 a, 61 b, 61 c, 61 d) during operation, and the at least one particle transport channel (60) passes through and/or faces the at least one particle reservoir (61 a, 61 b, 61 c, 61 d).

Description

Plain bearing device, transmission device with a plain bearing device and gas turbine engine with a plain bearing device

description

The present disclosure relates to a plain bearing device having the features of claim 1, a transmission device having the features of claim 12 and a gas turbine engine having the features of claim 14.

Plain bearings should guide components that move relative to one another as precisely, with little friction and without wear as possible. A lubricating film containing a fluid such as oil or fuel is arranged between the sliding surfaces of a plain bearing in the lubricating gap. It can happen that particles (e.g. as dirt, abrasion, etc.) move in the lubricating gap, which is fundamentally undesirable. Means for addressing this problem are known from US Pat. No. 5,320,431 A, US 2013/0230263 A1, GB 1 128 370, US Pat.

The task is to provide efficient means with which the negative effects of particles in the lubricating gap can be minimized. According to a first aspect, according to claim 1, there is provided a sliding bearing device having a lubricating film between sliding surfaces and having at least one particle transport channel in at least one sliding surface, the direction of the at least one particle transport channel

• in the case of a radial plain bearing device, at least in sections, has an angle a that is not equal to 90° to a plane perpendicular to the direction of rotation (R),

• in an axial sliding bearing device, at least in sections, has an angle a that is not equal to 0° to a cylindrical surface around the direction of rotation.

Thus, axial and radial slide bearing devices can have at least one particle transport channel, wherein the at least one particle transport channel is in fluidic contact with at least one particle reservoir during operation and that the at least one particle transport channel passes through the at least one particle reservoir and/or is directed towards it.

Depending on the type of bearing, the at least one particle transport channel is therefore non-radial and non-concentric, so that particles in the lubricating film can be transported in the axial direction in a radial plain bearing device and in the radial direction in an axial plain bearing device. During operation of the sliding bearing device, this transport of the particles takes place in the direction of a particle reservoir, which can be arranged in the sliding surface or (axially or radially, depending on the type of bearing) outside of the sliding surface.

In principle, it is possible to arrange the at least one particle transport channel and the at least one particle reservoir in a sliding surface of the sliding pair.

However, this is not mandatory since the at least one particle transport channel and the at least one particle reservoir can also be arranged in both sliding surfaces. It is also possible that the at least one particle transport channel in a Sliding surface is arranged and the at least one particle reservoir in the opposite sliding surface.

Additionally or alternatively, the at least one particle reservoir can be designed as a (e.g. groove-shaped) collecting channel in the circumferential direction of the sliding surface of the at least one sliding surface. It is also possible for the at least one particle reservoir to be in the form of an axial end of an axial plain bearing device or as a radial edge of a radial plain bearing device. The at least one particle reservoir can also be integrated into the particle transport channel, for example by opening into it. In principle, harmless forms of particle collection channels and/or particle reservoirs can also be used in a plain bearing device.

In one embodiment, the at least one particle transport channel is arranged helically in the at least one sliding surface of an axial plain bearing device, the helix angle of the particle transport channel being constant in the axial direction of the plain bearing device or changing in sections in the axial direction of the plain bearing device. The flow of the oil (possibly with the particles) through the at least one particle transport channel can be influenced by the selection of the screw angle. In particular, the helix angle of the at least one particle transport channel decreases towards an axial end or a radial edge. On the one hand, this ensures the desired effect of transporting particles, and on the other hand, the undesired effect of a discharge of the lubricating film fluid from the plain bearing functional surfaces is limited.

In a further embodiment, the cross-sectional area of the at least one particle transport channel can be embodied symmetrically or asymmetrically perpendicular to the direction of the particle transport channel or to the direction of the groove-shaped particle reservoir. The asymmetrical cross-sectional area can be oriented in such a way that it supports the formation of the lubricating film, for example in that the cross-sectional area approaches the plain bearing surface at a shallower angle in the direction of plain bearing movement than against the direction of plain bearing movement. In one embodiment, two groove-shaped particle transport channels can have angles relative to a plane perpendicular to the direction of rotation (in the case of the radial plain bearing device) or relative to a cylindrical surface about the direction of rotation (in the case of the axial plain bearing device) with different signs. This means that helical particle transport channels can also be used with changing directions of rotation.

In a further embodiment, the maximum depth and/or maximum width of the at least one particle transport channel and/or the at least one groove-shaped particle reservoir corresponds at least to the minimum thickness of the lubricating film. Depending on the application conditions of the plain bearing, the minimum thickness of the lubricating film is 0.005 mm or more. This means that the particle transport channel and/or the particle reservoir at the deepest point is at least as thick as the lubricating film. This means that particles whose size roughly corresponds to the thickness of the lubricating film can be transported or picked up.

Furthermore, the maximum depth of the at least one particle transport channel and/or the at least one groove-shaped particle reservoir can be less than 100 times the minimum thickness of the lubricating film. Depending on the application conditions of the plain bearing, 100 times the minimum thickness of the lubricating film is 0.5 mm or more.

In one embodiment, the maximum depth of the at least one particle reservoir can be greater than the maximum depth of the groove-shaped particle transport channels so that the particles can be picked up properly.

Also, the maximum width of the at least one particle transport channel and/or the at least one groove-shaped particle reservoir cannot exceed a value that would reduce the gross axial length by more than 10% if the sum of all maximum widths of the at least one particle transport channel and the at least one groove-shaped particle reservoir considered at the same circumferential position. The object is also achieved by a transmission device with at least one plain bearing device according to claims 1 to 11. In this case, the transmission device can be designed as a planetary gear and the plain bearing device can serve to support a planet wheel.

The object is also achieved by a gas turbine engine having the features of claim 14.

As noted elsewhere herein, the present disclosure may relate to a gas turbine engine, such as an aircraft engine. Such a gas turbine engine may include a core engine that includes a turbine, a combustor, a compressor, and a core shaft connecting the turbine to the compressor. Such a gas turbine engine may include a fan (having fan blades) positioned upstream of the core engine.

Arrangements of the present disclosure may be particularly, but not exclusively, beneficial for geared fans that are gear driven. Accordingly, the gas turbine engine may include a gearbox driven by the core shaft and the output of which drives the fan to rotate at a slower speed than the core shaft. Input to the gearbox may be direct from the core shaft or indirectly via the core shaft, for example via a spur shaft and/or spur gear. The core shaft may be rigidly connected to the turbine and compressor such that the turbine and compressor rotate at the same speed (with the fan rotating at a lower speed).

The gas turbine engine described and/or claimed herein may have any suitable general architecture. For example, the gas turbine engine may have any desired number of spools connecting the turbine and compressor, such as one, two, or three spools. For example only, the turbine coupled to the core shaft may be a first turbine, the compressor coupled to the core shaft may be a first compressor, and the core shaft may be a first core shaft. The core engine can also a second turbine, a second compressor, and a second core shaft connecting the second turbine to the second compressor. The second turbine, the second compressor, and the second core shaft may be arranged to rotate at a higher speed than the first core shaft.

In such an arrangement, the second compressor may be positioned axially downstream of the first compressor. The second compressor may be arranged to receive flow from the first compressor (e.g. directly receiving, e.g. via a generally annular duct).

The gearbox may be configured to be driven by the core shaft configured to rotate (e.g., in use) at the lowest speed (e.g., the first core shaft in the example above). For example, the transmission may be configured to be driven only by the core shaft that is configured to rotate (e.g., in use) at the lowest speed (e.g., only the first core shaft and not the second core shaft in the example above ). Alternatively, the gearbox may be arranged to be driven by one or more shafts, for example the first and/or the second shaft in the example above.

In a gas turbine engine as described and/or claimed herein, a combustor may be provided axially downstream of the fan and compressor (or compressors). For example, the burner device can be located directly downstream of the second compressor (e.g. at its outlet) if a second compressor is provided. As another example, if a second turbine is provided, the flow at the exit of the compressor may be directed to the inlet of the second turbine. The burner device may be provided upstream of the turbine(s).

The or each compressor (for example the first compressor and the second compressor as described above) may comprise any number of stages, for example multiple stages. Each stage may include a row of rotor blades and a row of stator blades, which are variable stator blades can act (ie the angle of attack can be variable). The row of rotor blades and the row of stator blades may be axially offset from one another.

The or each turbine (such as the first turbine and the second turbine as described above) may include any number of stages, such as multiple stages. Each stage may include a row of rotor blades and a row of stator blades. The row of rotor blades and the row of stator blades may be axially offset from one another.

Each fan blade may have a radial span extending from a root (or hub) at a radially inner gas flow location or extending from a 0% span position to a 100% span tip. The ratio of the radius of the fan blade at the hub to the radius of the fan blade at the tip may be less than (or on the order of): 0.4, 0.39, 0.38, 0.37, 0.36, 0 .35, 0.34, 0.33, 0.32, 0.31, 0.3, 0.29, 0.28, 0.27, 0.26 or 0.25. The ratio of the radius of the fan blade at the hub to the radius of the fan blade at the tip may be in a closed range bounded by two values in the previous sentence (i.e. the values may form upper or lower limits). These ratios can be generically referred to as the hub-to-tip ratio. The radius at the hub and the radius at the tip can both be measured at the leading edge (or the axially most forward edge) of the blade. The hub-to-tip ratio is of course related to the portion of the fan blade over which the gas flows, i. H. the portion radially outward of any platform.

The radius of the fan can be measured between the centerline of the engine and the tip of the fan blade at its leading edge. The diameter of the fan (which can generally be twice the radius of the fan) can be greater than (or on the order of): 250 cm (about 100 inches), 260 cm, 270 cm (about 105 inches), 280 cm (about 110 inches), 290 cm (about 115 inches), 300 cm (about 120 inches), 310 cm (about 123 inches), 320 cm (about 125 inches), 330 cm (about 130 inches), 340 cm (about 135 inches ), 350 cm (about 139 inches), 360 cm (about 140 inches), 370 cm (about 145 inches), 380 cm (about 150 inches), or 390 cm (about 155 inches). The fan diameter can are in a closed range bounded by two of the values in the preceding sentence (ie the values can form upper or lower bounds).

The speed of the fan can vary during operation. Generally, the RPM is lower for larger diameter fans. By way of non-limiting example only, the speed of the fan may be less than 2500 rpm, for example less than 2300 rpm, under constant speed conditions. By way of further non-limiting example only, the speed of the fan at constant speed conditions for an engine having a fan diameter in the range of 250 cm to 300 cm (e.g. 250 cm to 280 cm) in the range of 1700 rpm to 2500 rpm, for example in the range from 1800 rpm to 2300 rpm, for example in the range from 1900 rpm to 2100 rpm. By way of further non-limiting example only, the speed of the fan at constant speed conditions for an engine having a fan diameter in the range 320 cm to 380 cm may be in the range 1200 rpm to 2000 rpm, for example in the range 1300 rpm min to 1800 rpm, for example in the range of 1400 rpm to 1600 rpm.

In use of the gas turbine engine, the fan (with associated fan blades) rotates about an axis of rotation. This rotation causes the tip of the fan blade to move at a speed Upeak. The work done by the fan blades on the flow results in an increase in the enthalpy dH of the flow. A fan tip load can be defined as dH/ ^Upeak2 , where dH is the enthalpy rise (e.g., the average 1-D enthalpy rise) across the fan and Upeak is the (translational) velocity of the fan tip, e.g., at the leading edge of the tip (which can be defined as the leading edge fan tip radius times the angular velocity). Fan peak loading at constant speed conditions can be more than (or on the order of): 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38 , 0.39 or 0.4 (where all units in this section are Jkg' ¹ K' ¹ /(ms' ¹ ) ² ). The fan peak load can be in a closed range bounded by two of the values in the previous sentence (ie the values can form upper or lower bounds). Gas turbine engines according to the present disclosure may have any desired bypass ratio, where bypass ratio is defined as the ratio of the mass flow rate of flow through the bypass duct to the mass flow rate of flow through the core at constant speed conditions. In some arrangements, the bypass ratio may be more than (or on the order of): 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15, 5, 16, 16.5 or 17 (lie). The bypass ratio can be in a closed range bounded by two of the values in the previous sentence (ie the values can form upper or lower limits). The bypass channel can be essentially ring-shaped. The bypass duct can be located radially outside of the core engine. The radially outer surface of the bypass duct may be defined by an engine nacelle and/or a fan casing.

The overall pressure ratio of a gas turbine engine, as described and/or claimed herein, may be defined as the ratio of the ram pressure upstream of the fan to the ram pressure at the exit of the ultra-high pressure compressor (prior to the entrance to the combustor). As a non-limiting example, the overall pressure ratio of a gas turbine engine described and/or claimed herein at constant speed may be greater than (or on the order of): 35, 40, 45, 50, 55, 60, 65, 70, 75 (to lie). The overall pressure ratio can be in a closed range bounded by two of the values in the previous sentence (i.e. the values can form upper or lower limits).

The specific thrust of an engine can be defined as the net thrust of the engine divided by the total mass flow through the engine. At constant speed conditions, the specific thrust of an engine described and/or claimed herein may be less than (or of the order of): 110 Nkg ^-1 s, 105 Nkg ^-1 s, 100 Nkg ^-1 s, 95 Nkg ^{- 1} s, 90 Nkg ^-1 s, 85 Nkg ^-1 s or 80 Nkg ^-1 s (lie). The specific thrust can be in a closed range bounded by two of the values in the previous sentence (ie the values can form upper or lower limits). Such Engines can be particularly efficient compared to conventional gas turbine engines.

A gas turbine engine described and/or claimed herein may have any desired maximum thrust. By way of non-limiting example only, a gas turbine described and/or claimed herein is capable of producing a maximum thrust of at least (or of the order of): 160 kN, 170 kN, 180 kN, 190 kN, 200 kN, 250 kN , 300 kN, 350 kN, 400 kN, 450 kN, 500 kN or 550kN. The maximum thrust can be in a closed range bounded by two of the values in the previous sentence (i.e. the values can form upper or lower limits). The thrust referred to above may be the maximum net thrust at standard atmospheric conditions at sea level plus 15°C (ambient pressure 101.3 kPa, temperature 30°C) with the engine static.

In use, the temperature of the flow at the entrance to the high pressure turbine can be particularly high. This temperature, which may be referred to as TET, may be measured at the exit to the combustor, for example immediately upstream of the first turbine blade, which in turn may be referred to as a nozzle vane. At constant speed the TET can be (are) at least (or in the order of): 1400 K, 1450 K, 1500 K, 1550 K, 1600 K or 1650 K. The TET at constant speed can be in a closed range bounded by two of the values in the previous sentence (i.e. the values can form upper or lower limits). For example, the maximum TET in use of the engine may be at least (or on the order of): 1700K, 1750K, 1800K, 1850K, 1900K, 1950K, or 2000K. The maximum TET can be in a closed range bounded by two of the values in the previous sentence (i.e. the values can form upper or lower bounds). For example, the maximum TET may occur at a high thrust condition, such as an MTO (Maximum Take-Off Thrust) condition.

A fan blade and/or fan blade aerofoil described and/or claimed herein may be of any suitable Material or a combination of materials are made. For example, at least a portion of the fan blade and/or blade may be formed at least in part from a composite such as a metal matrix composite and/or an organic matrix composite such as e.g. B. carbon fiber, are produced. As another example, at least a portion of the fan blade and/or blade may be formed at least in part from a metal such as aluminum. a titanium-based metal, or an aluminum-based material (such as an aluminum-lithium alloy) or a steel-based material. The fan blade may include at least two sections made using different materials. For example, the fan blade may have a leading protective edge made using a material that can withstand impact (e.g., from birds, ice, or other material) better than the rest of the blade. Such a leading edge can be made, for example, using titanium or a titanium-based alloy. Thus, as just one example, the fan blade may have a carbon fiber or aluminum based body (such as an aluminum-lithium alloy) with a titanium leading edge.

A fan described and/or claimed herein may include a central section from which the fan blades may extend, for example in a radial direction. The fan blades can be attached to the center section in any desired manner. For example, each fan blade may include a locating device engageable with a corresponding slot in the hub (or disc). By way of example only, such a fixation device may be in the form of a dovetail which may be inserted into and/or engaged with a corresponding slot in the hub/disc to fix the fan blade to the hub/disc. As another example, the fan blades may be integrally formed with a center section. Such an arrangement may be referred to as a blisk or a bling. Any suitable method may be used to manufacture such a blisk or bling. For example, at least a portion of the fan blades may be machined from an ingot and/or at least a portion of the fan blades may be welded, such as by welding. B. linear friction welding, to be attached to the hub / disc. The gas turbine engines described and/or claimed herein may or may not be provided with a VAN (Variable Area Nozzle). Such a nozzle with a variable cross-section can, during operation, allow the exit cross-section of the bypass channel to be varied. The general principles of the present disclosure may apply to engines with or without a VAN.

The gas turbine fan described and/or claimed herein may have any desired number of fan blades, such as 16, 18, 20, or 22 fan blades.

As used herein, constant speed conditions may mean the constant speed conditions of an aircraft on which the gas turbine engine is mounted. Such constant speed conditions may conventionally be defined as the conditions during the middle part of flight, for example the conditions experienced by the aircraft and/or engine between (in terms of time and/or distance) the end of the climb and the beginning of the descent. will.

By way of example only, the forward speed at the constant speed condition may be at any point in the range Mach 0.7 to 0.9, e.g. 0.75 to 0.85, e.g. 0.76 to 0.84, e.g. 0.77 to 0 .83, for example 0.78 to 0.82, for example 0.79 to 0.81, for example of the order of Mach 0.8, of the order of Mach 0.85 or in the range of 0.8 to 0, 85 lie. Any speed within these ranges can be the cruise condition. For some aircraft, cruise conditions may be outside of these ranges, for example below Mach 0.7 or above Mach 0.9.

As an example only, the constant velocity conditions may correspond to standard atmospheric conditions at an altitude ranging from 10,000 m to 15,000 m, for example in the range from 10,000 m to 15,000 m 12,000 m, for example in the range from 10,400 m to 11,600 m (about 38,000 feet) for example in the range from 10,500 m to 11,500 m, for example in the range from 10,600 m to 11,400 m, for example in the range from 10,700 m (about 35,000 feet) to 11,300 m, for example in the range from 10,800 m to 11,200 m, for example in the range from 10,900 m to 11,100 m, for example in the order of 11,000 m. The constant velocity conditions can correspond to standard atmospheric conditions at any given altitude in these ranges.

As an example only, the constant speed conditions may correspond to: a forward Mach number of 0.8; a pressure of 23,000 Pa and a temperature of -55 °C.

As used throughout, "constant speed" or "constant speed conditions" can mean the aerodynamic design point. Such an aerodynamic design point (or ADP) may correspond to the conditions (including, for example, Mach number, environmental conditions, and thrust requirement) for which the fan operation is designed. This may mean, for example, the conditions at which the fan (or gas turbine engine) is designed to be at its optimum efficiency.

In operation, a gas turbine engine described and/or claimed herein may be operated at the constant speed conditions defined elsewhere herein. Such constant speed conditions may be dictated by the constant speed conditions (e.g., mid-flight conditions) of an aircraft on which at least one (e.g., two or four) gas turbine engine(s) may be mounted to provide thrust.

It will be understood by those skilled in the art that a feature or parameter described in relation to one aspect above may be applied to any other aspect provided they are not mutually exclusive. Furthermore, any feature or any parameter described herein may be applied to any aspect and/or combined with any other feature or parameter described herein, provided they are not mutually exclusive.

Exemplary embodiments will now be described with reference to the figures; show in the figures:

Figure 1 is a side sectional view of a gas turbine engine;

Figure 2 is a close-up side sectional view of an upstream portion of a gas turbine engine;

Figure 3 is a partially cut-away view of a gearbox for a gas turbine engine;

FIG. 4 shows a sectional view through a known radial sliding bearing device;

FIG. 5 shows a first embodiment of a radial plain bearing device with helical particle transport channels;

FIG. 6 shows a second embodiment of a radial sliding bearing device with helical particle transport channels;

FIG. 7a shows a cross section of a groove-shaped particle transport channel or a groove-shaped particle reservoir with a symmetrical cross section;

FIG. 7b shows a cross-section of a groove-shaped particle transport channel or a groove-shaped particle reservoir with an asymmetrical cross-section;

FIG. 8 schematically shows an embodiment of a particle transport channel with an integrated particle reservoir;

Figure 9 shows schematically an embodiment with a helical particle transport channel with a variable helix angle;

FIG. 10 shows a schematic of an embodiment of an axial plain bearing device with a particle transport channel and particle reservoirs.

Possible applications of embodiments of a plain bearing device 50 (see, for example, FIGS. 5 and 6) are described below primarily in connection with a gear, in particular a planetary gear 30, which is used in a gas turbine engine 10. However, the applications are not limited to this area.

Figure 1 shows a gas turbine engine 10 with a main axis of rotation 9. The engine 10 includes an air inlet 12 and a fan 23 that produces two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 includes a core 11 that receives the core airflow A . The core engine 11 includes, in axial flow order, a low pressure compressor 14, a high pressure compressor 15, a combustor 16, a high pressure turbine 17, a low pressure turbine 19, and a core exhaust nozzle 20. An engine nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic planetary gear 30.

During operation, the core air flow A is accelerated and compressed by the low-pressure compressor 14 and conducted into the high-pressure compressor 15, where further compression takes place. The compressed air discharged from the high pressure compressor 15 is directed into the combustor 16 where it is mixed with fuel and the mixture is burned. The resultant hot products of combustion then propagate through and thereby drive the high and low pressure turbines 17, 19 before being expelled through the nozzle 20 to provide some thrust. The high pressure turbine 17 drives the high pressure compressor 15 through a suitable connecting shaft 27 . The fan 23 generally provides the bulk of the thrust ready. The epicyclic planetary gear 30 is a reduction gear.

An exemplary arrangement for a geared fan gas turbine engine 10 is shown in FIG. The low-pressure turbine 19 (see FIG. 1) drives the shaft 26 which is coupled to a sun gear 28 of the epicyclic planetary gear set 30 . A plurality of planetary gears 32, which are coupled to one another by a planetary carrier 34, are located radially outward of the sun gear 28 and mesh therewith. The planetary carrier 34 guides the planetary gears 32 to orbit synchronously about the sun gear 28 while allowing each planetary gear 32 to rotate about its own axis. Planet carrier 34 is coupled to fan 23 via linkages 36 to drive its rotation about engine axis 9 . An outer gear or ring gear 38, which is coupled to a stationary support structure 24 via linkage 40, is radially outward of the planetary gears 32 and meshes therewith.

It is noted that the terms "low pressure turbine" and "low pressure compressor" as used herein may be construed to mean the lowest pressure turbine stage and the lowest pressure compressor stage, respectively (i.e. not including the fan 23) and/or the turbine and compressor stages interconnected by the lowest speed connecting shaft 26 in the engine (ie not comprising the gearbox output shaft driving the fan 23). In some writings, the "low-pressure turbine" and "low-pressure compressor" referred to herein may alternatively be known as the "intermediate-pressure turbine" and "intermediate-pressure compressor." Using such alternative nomenclature, the fan 23 may be referred to as a first compression stage or lowest pressure compression stage.

The epicyclic planetary gear 30 is shown in more detail in FIG. 3 by way of example. The sun gear 28, planet gears 32 and ring gear 38 each include teeth on their periphery to allow meshing with the other gears. However, for the sake of clarity, only exemplary portions of the teeth are shown in FIG. Although four planetary gears 32 are illustrated, those skilled in the art will appreciate that they are within the scope of the claims Invention more or less planet gears 32 can be provided. Practical applications of an epicyclic planetary gear 30 generally include at least three planetary gears 32.

The epicyclic planetary gear 30 shown by way of example in FIGS. 2 and 3 is a planetary gear in which the planet carrier 34 is coupled to an output shaft via linkage 36, with the ring gear 38 being fixed. However, any other suitable type of planetary gear 30 may be used. As another example, the planetary gear set 30 may be a wye arrangement in which the planetary carrier 34 is held fixed while allowing the ring gear (or ring gear) 38 to rotate. With such an arrangement, the fan 23 is driven by the ring gear 38 . As another alternative example, the transmission 30 may be a differential where both the ring gear 38 and the planetary carrier 34 are allowed to rotate.

It should be understood that the arrangement shown in Figures 2 and 3 is exemplary only and various alternatives are within the scope of the present disclosure. Any suitable arrangement for positioning the gearbox 30 within the engine 10 and/or connecting the gearbox 30 to the engine 10 may be used, for example only. As another example, the connections (e.g., the linkages 36, 40 in the example of Figure 2) between the transmission 30 and other parts of the engine 10 (such as the input shaft 26, the output shaft, and the attached structure 24) have some degree of rigidity or flexibility. As another example, any suitable arrangement of bearings between rotating and stationary parts of engine 10 (e.g., between the input and output shafts of the transmission and fixed structures such as the transmission case) may be used and the disclosure is not limited to the exemplary arrangement of FIG. For example, those skilled in the art will readily appreciate that the output and support linkage arrangements and bearing locations for a star configuration (described above) of the transmission 30 would typically differ from those exemplified in FIG. Accordingly, the present disclosure extends to a gas turbine engine having any arrangement of gear types (e.g., star or epicyclic planetary), support structures, input and output shaft arrangement, and bearing locations.

Optionally, the transmission can drive auxiliary and/or alternative components (e.g. the medium-pressure compressor and/or a booster).

Other gas turbine engines to which the present disclosure may have application may have alternative configurations. For example, such engines can have an alternative number of compressors and/or turbines and/or an alternative number of connecting shafts. As a further example, the gas turbine engine shown in Figure 1 has a split flow nozzle 20, 22, meaning that the flow through the bypass duct 22 has its own nozzle separate from the engine core nozzle 20 and radially outward therefrom. However, this is not limiting and any aspect of the present disclosure may also apply to engines where flow through bypass duct 22 and flow through core 11 are upstream of (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. be mixed or combined. One or both nozzles (whether mixed or split flow) may have a fixed or variable area. For example, although the example described relates to a turbofan engine, the disclosure may apply to any type of gas turbine engine, such as a turbofan engine. an open rotor (where the fan stage is not surrounded by an engine nacelle) or a turboprop engine. In some arrangements, the gas turbine engine 10 may not include a gearbox 30.

The geometry of the gas turbine engine 10 and components thereof is or are defined by a conventional axis system having an axial direction (aligned with the axis of rotation 9), a radial direction (in the bottom-up direction in Figure 1) and a circumferential direction (perpendicular to the view in Figure 1). The axial, radial and circumferential directions are perpendicular to one another. A typical area of use for a plain bearing device 50 is, for example, the bearing of the planet gears 32. In principle, however, the plain bearing devices 50 used below can be used for bearing shafts or in other transmissions, for example in ships or wind turbines.

In the following, radial plain bearing devices will first be discussed. An embodiment of an axial plain bearing device is then discussed in connection with FIG. 10 .

Radial plain bearing devices 50 include a cylindrical member positioned within a structural member having a cylindrical bore, and both members rotate relative to one another. The diameter of the cylindrical element and the diameter of the cylindrical bore are chosen to define a small clearance. A lubricant such as oil is introduced into the lubricating gap between two sliding surfaces 51, 52 to form a fluid film.

A relative rotation of the two elements creates a pressure distribution in this fluid film, which can transfer the load between the elements rotating relative to one another. The load is perpendicular to the cylindrical surfaces of the journal bearing assembly 50, i.e. radial to the axis of relative rotation between the elements. Therefore, the radial slide bearing device is a constructive means of transferring the radial load between two members rotating relative to each other while generating minimal friction loss.

The cylindrical surfaces of the journal bearing device can be profiled to facilitate the establishment of a pressure distribution of the fluid film and thus optimize the ability to transmit the radial load. One or both of the cylindrical sliding surfaces 51, 52 of the sliding bearing device 50 can be coated to facilitate operation when the liquid film pressure is not fully built up when starting or stopping the relative rotation.

An example of the application of such a plain bearing is a planetary gear 30 in which the planet gears 32 rotate about an axis defined by the planet carrier 34 . In doing so, a radial load due to the transmission 30 transmitted power and relatively transmitted due to the centrifugal load from the planetary gear rotation. The planet wheel pin is arranged in the planet carrier 34 . In this configuration, the pinion pin is the cylindrical member of the journal bearing assembly 50, and the pinion gear 32 is the member having the cylindrical bore.

The thickness of the lubricating film in the sliding bearing device 50 is usually small. For example, the minimum lubricating film thickness can be in the order of 0.005 mm and therefore offers only limited robustness against particle contamination in the lubricant (e.g. oil) with particles.

For example, the lubricant supplied to the plain bearing device 50 may be contaminated with particles, or particles may be generated in the plain bearing device 50, for example by abrasion, if the lubricating film is disturbed locally or temporarily, for example by temporary overload or misalignment. In such a case, there is direct contact between the sliding surfaces 51, 52.

The formation of particles P can have consequential effects (e.g. due to abrasion), which can quickly lead to an accumulation of further particles, which further disrupt the lubricating film and ultimately to failure (e.g. overheating, seizing) of the slide bearing device 50 can lead.

The particle movement is predominantly circumferential relative to the axis of rotation, whereby there can be a more or less large axial displacement of the particles P. The probability that particles can escape from the slide bearing device 50 is low.

On the other hand, the accumulation of further (secondary generated) particles P at the same axial position of the primary particle P is quite probable. This is particularly relevant to the plain bearing devices 50 where the axial length and diameter of the cylindrical surfaces are large in relation to the minimum liquid film thickness. In these embodiments, the probability that the particles P are discharged is rather small. 4 shows a fundamentally known design of a radial slide bearing device 50 . Here the cylindrical element 53 is intended to rotate in direction R within the cylindrical bore 54 . The sliding surfaces 51, 52 are located on the outside of the cylindrical element 53 or on the inside of the cylindrical bore 54. The lubricating film is located between the sliding surfaces 51, 52.

A few embodiments of a radial slide bearing device 50 are described below, in which particle transport channels 60 and particle reservoirs 61 are used.

5 and 6 each show a plan view of a sliding surface 51 of a radial sliding bearing device 50, particle transport channels 60 and particle reservoirs 61a, 61b being arranged in the sliding surface 51.

The sliding surface 51 can be arranged in the cylindrical surface of the cylindrical element 53 (e.g. a bearing bolt) or in the cylindrical bore 54 (e.g. the inside of the sliding bearing device 50). In principle, it is also possible (but not shown here) that both sliding surfaces 51 , 52 have particle transport channels 60 and particle reservoirs 61a or that particle transport channels 60 and particle reservoirs 61a are distributed over different sliding surfaces 51 , 52 . The particle transport channels 60 are in fluidic contact with the particle reservoirs 61a since they open into them and they are filled with oil (and optionally with particles P) during operation.

The particle transport channels 60 are designed here as groove-shaped collecting channels.

The particle transport channels 60 serve to guide particles P in the lubricating film out of the contact area of the sliding bearing surfaces 51, 52 by relative rotation and ultimately to keep them in the particle reservoirs 61a, 61b. In addition, the particle reservoirs 61a in a sliding surface 51, 52 can also enhance liquid film pressure build-up to allow radial load transfer.

Two helical particle transport channels 60 are shown in FIG. 5, ie the groove-shaped particle transport channels 60 run around on the sliding surface 51. the respective helix angle a', a" is not equal to 90° relative to a plane perpendicular to the direction of rotation R.

As the particle transport channels 60 rotate, the particles P are axially displaced or agitated due to the helical motion relative to the respective axial position that these particles P had when they entered the slide bearing device 50 or when they were generated in the slide bearing device 50 became. The gradient angles a, a' of the particle transport channels 60 are selected in such a way that the particles P are guided axially in the direction of one of the two particle reservoirs 61a, 61b with the relative rotation between the plain bearing elements. This is shown in FIG. 5 by arrows.

In the illustrated embodiment, the first particle reservoirs 61a are designed as circumferential, mutually parallel channels that lie in a plane perpendicular to the direction of rotation R. The second particle reservoirs 61b are each arranged at the axial ends of the sliding surface 51 and are shown as hatched areas in FIG. 5 . The particle reservoirs 61a, 61b can each be introduced into the sliding surface 51 as grooves.

The particle reservoirs 61a, 61b collect the particles P that are still inside the slide bearing device 50, but in a location and in a function that allows the thickness of the lubricating film and the pressure required to ensure the functionality of the slide bearing device 50, not be affected. As soon as a relevant amount of particles P has collected in the particle reservoirs 61a, 61b, the particles P should be removed during maintenance work.

In the embodiment according to FIG. 5 it is assumed that the direction of rotation is always constant since the pitch angles are either positive or negative.

For plain bearing devices 50 in which rotations occur in both directions during operation, particle transport channels 60 in the sense of the embodiment in FIG. 5 with positive and negative pitch angles are useful (see FIG. 6), the particle transport channels 60 then crossing. The two particle transport channels 60, 60' have pitch angles a with different signs.

The particles P are either conveyed axially out of the slide bearing device 50 (particle reservoirs 61b in each case at the axial end of the slide bearing device 50) or lead them to one of the particle reservoirs 61a in the circumferential direction.

The arrangement of the particle transport channels 60 is designed in such a way that particles P are guided to the nearest particle reservoir in each case. However, with a rotation in both directions and with transport channels arranged with both a positive and a negative angle, this means a 50% probability that a particle P will end up in the “wrong” particle reservoir. Accordingly, the achievable improvement in the robustness of the plain bearing device against particle contamination is lower if the plain bearing is provided for both directions of rotation.

The maximum depth T (see Fig. 7A, 7B) of the particle transport channels 60 and the groove-shaped first particle reservoirs 61a correspond to at least the minimum film thickness of the lubricating film in the slide bearing device 50 to ensure that particles P equal to or smaller than the minimum film thickness are detected be able.

Greater depths of the grooves enable larger particles P to be captured. The maximum possible depth of both the particle transport channels 60 and the first groove-shaped particle reservoir 61a is determined by the need to ensure a fluid film pressure distribution sufficient for radial load transfer functionality.

In general, maximum depth T is a function of groove width, with greater width requiring less maximum depth.

In general, the maximum depth T will not exceed a value 100 times the minimum lubricating film thickness. The maximum depth of the groove-shaped particle reservoirs 61a should be greater than the maximum depth of the particle transport channels 60 to ensure sufficient capacity for collecting particles P until maintenance is possible or required. The depth T of the particle transport channels 60 can basically be constant, but can also be variable along the particle transport channels 60 .

The maximum width S of the particle transport channels 60 and the groove-shaped particle reservoirs 61a (see FIGS. 7A, 7B) is at least equal to the minimum film thickness of the lubricating film.

Similar to the depth T, the width S of the groove-shaped particle transport channels 60 and the particle reservoirs 61 is also limited by the requirement to still ensure a fluid film pressure distribution that is sufficient for the functionality to transfer the radial load.

In general, the maximum width S of the groove-shaped particle transport channels 60 and the particle reservoirs 61a will not exceed a value that would reduce the gross axial length of the plain bearing by more than 10% when considering the sum of all groove widths at the same circumferential position. If present, it is preferable to increase the width of the collector grooves compared to the width of the turning grooves to ensure sufficient capacity to collect particles until required maintenance.

The cross-sectional areas Q of the groove-shaped particle transport channels 60 or particle reservoirs 61 can be symmetrical or asymmetrical with respect to a central axis (shown as a dashed line in FIGS. 7A, 7B) of the cross section Q. FIGS. 7A, 7B show a sectional view perpendicular to the direction of the particle transport channel 60 or the groove-shaped particle reservoir 61a, 61c.

An asymmetric cross-section Q (Fig. 7B), particularly of the helical particle transport channels 60 (see Fig. 6), can facilitate maintaining adequate liquid film pressure.

With such an embodiment, the robustness of the radial load transfer function of the slide bearing device 50 with respect to particle contamination of the lubricating film is increased and thus the reliability clearly improved.

Particle contamination of the lubricating film can be caused, for example, by particle contamination of the lubricating fluid supplied to the plain bearing device 50 or by particles P which are generated in the plain bearing device 50 due to a local and temporary breakdown of the liquid film as a result of, for example, a temporary overload or a temporary misalignment of the axes of rotation. This is particularly relevant for large plain bearings, i.e. where the ratio of the bearing width or bearing diameter to the minimum film thickness exceeds a value of around 10000.

Embodiments described so far have radially encircling particle reservoirs 61a or axially terminal particle reservoirs 61b.

A detail of a particle reservoir 61 d is shown in FIG. 8 , which is integrated into a groove-shaped particle transport channel 60 in a sliding surface 51 , 52 , so that the particle reservoir 61 d can also be referred to as being groove-shaped. This takes place here in the form of an extension at the end of the particle transport channel 60.

Some embodiments (FIGS. 5 or 6) have helical particle transport channels 60 in which the helical angle α is constant. This is not mandatory. FIG. 8 shows an embodiment according to FIG. 5 or 6, in which the helix angle a becomes smaller in the direction of the radially encircling particle reservoir 61a (cn<02). This reduces the undesired effect of draining the lubricating film fluid while maintaining the desired effect of transporting particles.

In the previous embodiments (FIGS. 4 to 9), reference was made to radial sliding bearing devices 50.

In principle, however, it is also possible to use particle transport channels 60 and particle reservoirs in axial slide bearing devices 50 . FIG. 10 shows a schematic plan view of a plain bearing surface 51 of an axial plain bearing device 50 . The axis of rotation R is perpendicular to mapping plane.

In the sliding surface 51, two concentrically arranged groove-shaped particle reservoirs 61a are arranged. On the outer edge of the sliding surface 51 of the axial sliding bearing device 50, a peripheral particle reservoir 61c is additionally or alternatively arranged, which corresponds to the terminal, axial particle reservoir 61b.

Two particle transport channels 60 are shown merely as an example, which lead from the space between the groove-shaped particle reservoirs 61a into the latter. Additionally or alternatively, a particle transport channel 60 can also lead from the outer area of the sliding surface to the outer particle reservoir 61c.

The particle transport channels have an angle a that is not equal to 0° to a cylindrical surface around the direction of rotation R, i.e. they are not concentric but inclined to the particle reservoirs 61a, 61c.

The embodiments for plain bearing devices described here can basically be used in all plain bearing applications in transmissions or shaft bushings. Other areas of application would be, for example, ship technology or wind turbines.

It should be understood that the invention is not limited to the embodiments described above, and various modifications and improvements can be made without departing from the concepts described herein. Any of the features may be employed separately or in combination with any other feature, provided they are not mutually exclusive, and the disclosure extends to and encompasses all combinations and sub-combinations of one or more features described herein. Reference List

9 main axis of rotation

10 gas turbine engine

11 core engine

12 air intake

14 low-pressure compressors

15 high-pressure compressor

16 incinerator

17 high pressure turbine

18 bypass exhaust nozzle

19 low pressure turbine

20 core thruster

21 engine nacelle

22 bypass channel

23 fans

24 stationary support structure

26 wave

27 connecting shaft

28 sun gear

30 gears, planetary gears

32 planet gears

34 planet carriers

36 linkage

38 ring gear

40 linkage

50 sliding bearing device

51 first sliding surface

52 second sliding surface

53 cylindrical element

54 cylindrical bore 60 particle transport channel

61a groove-shaped particle reservoir in sliding surface

61b Particle reservoir at an axial end of an axial plain bearing device

61c particle reservoir on a radial edge of a radial plain bearing device 61d particle reservoir integrated in particle transport channel

A core airflow

B Bypass airflow

Q cross-sectional area of particle transport channel / particle reservoir R direction of rotation

S maximum width of the particle transport channel

T maximum depth of the particle transport channel a angle of the particle transport channel relative to a reference surface

Claims

- 29 -Claims

1. Plain bearing device (50) with a lubricating film between sliding surfaces (51, 52) and with at least one particle transport channel (60) in at least one sliding surface (51, 52) of the plain bearing device (50), the direction of the at least one particle transport channel (60)

• in the case of a radial slide bearing device (50), at least in sections, has an angle (a) that is not equal to 90° to a plane perpendicular to the direction of rotation (R),

• in an axial plain bearing device (50), at least in sections, has an angle (a) other than 0° to a cylindrical surface around the direction of rotation (R), and the at least one particle transport channel (60) is in fluid contact with at least one particle reservoir (61 a , 61 b, 61 c, 61 d) and that the at least one particle transport channel (60) passes through the at least one particle reservoir (61a, 61b, 61c, 61 d) and/or is directed towards it.

2. Plain bearing device (50) according to claim 1, characterized in that the at least one particle reservoir (61a) as a collecting channel in the circumferential direction of the sliding surface (51, 52) of the at least one sliding surface (51, 52), as an axial end (61b) an axial sliding bearing device (50), as a radial edge (61c) of a radial sliding bearing device (50) and/or as a particle reservoir (61d) integrated into a particle transport channel (60).

3. Plain bearing device (50) according to Claim 1 or 2, characterized in that the at least one particle transport channel (60) is arranged helically in the at least one sliding surface (51, 52) of an axial plain bearing device (50), the helix angle being in the axial direction of the Plain bearing device (50) is constant or changes in sections in the axial direction of the plain bearing device (50). - 30 -

4. plain bearing device (50) according to claim 3, characterized in that the helix angle of the at least one particle transport channel (60) in the direction of an axial end (61b) or a radial edge (61c) becomes smaller.

5. Plain bearing device (50) according to at least one of the preceding claims, characterized in that the cross-sectional area (Q) of the at least one particle transport channel (60) is symmetrical perpendicular to the direction of the particle transport channel (60) or perpendicular to the direction of the groove-shaped particle reservoir (61a, 61c). or is asymmetrical.

6. Plain bearing device (50) according to Claim 5, characterized in that the asymmetrical cross-sectional area (Q) is oriented in such a way that it supports the formation of the lubricating film, in particular in that the cross-sectional area runs towards the plain bearing surface at a shallower angle in the direction of the plain bearing movement than opposite to the direction of plain bearing movement.

7. Plain bearing device (50) according to at least one of the preceding claims, characterized in that two groove-shaped particle transport channels (60', 60') have angles (a) with different signs.

8. Plain bearing device (50) according to at least one of the preceding claims, characterized in that the maximum depth (T) and/or maximum width (S) of the at least one particle transport channel (60) and/or the at least one groove-shaped particle reservoir (61a, 61 d) corresponds at least to the minimum thickness of the lubricating film.

9. plain bearing device (50) according to at least one of the preceding claims, characterized in that the maximum depth (T) of the at least one particle transport channel (60) and / or the at least one groove-shaped particle reservoir (61a, 61d) is smaller than the 100- times the minimum thickness of the lubricating film.

10. plain bearing device (50) according to at least one of the preceding claims, characterized in that the maximum depth (T) of the at least a particle reservoir (61a, 61d) is greater than the maximum depth of the groove-shaped particle transport channels (60).

11. Plain bearing device (50) according to at least one of the preceding claims, characterized in that the maximum width (S) of the at least one particle transport channel (60) and/or of the at least one groove-shaped particle reservoir (61a, 61d) does not exceed a value that the gross axial length would be reduced by more than 10% if one considers the sum of all maximum widths (S) of the at least one particle transport channel (60) and the at least one groove-shaped particle reservoir (61a, 61d) at the same circumferential position.

12. Transmission device with at least one plain bearing device (50) according to any one of the preceding claims.

13 Transmission device according to claim 12, characterized in that this is designed as a planetary gear and the plain bearing device (50) is the bearing of a planet wheel.

A gas turbine engine (10) for an aircraft, comprising: a core engine (11) including a turbine (19), a compressor (14), and a core shaft (26) connecting the turbine to the compressor; a fan (23) positioned upstream of the core engine (11), the fan (23) including a plurality of fan blades; and a gear (30) drivable by the core shaft (26), the fan (23) being drivable by the gear (30) at a lower speed than the core shaft (26), the gear (30) being a gear device according to claim 12 or 13.