Patent ID: 12196261

DETAILED DESCRIPTION OF THE INVENTION

FIG.1illustrates a gas turbine engine10having a main axis of rotation9. The engine10comprises an air inlet12and a thrust fan23that generates two air flows: a core air flow A and a bypass air flow B. The gas turbine engine10comprises a core11which receives the core air flow A. In the sequence of axial flow, the engine core11comprises a low-pressure compressor14, a high-pressure compressor15, a combustion device16, a high-pressure turbine17, a low-pressure turbine19, and a core thrust nozzle20. An engine nacelle21surrounds the gas turbine engine10and defines a bypass duct22and a bypass thrust nozzle18. The bypass air flow B flows through the bypass duct22. The fan23is attached to and driven by the low-pressure turbine19by way of a shaft26and an epicyclic gearbox30. The shaft26herein is also referred to as the core shaft.

During use, the core air flow A is accelerated and compressed by the low-pressure compressor14and directed into the high-pressure compressor15, where further compression takes place. The compressed air expelled from the high-pressure compressor15is directed into the combustion device16, where it is mixed with fuel and the mixture is combusted. The resulting hot combustion products then propagate through the high-pressure and the low-pressure turbines17,19and thereby drive said turbines, before being expelled through the nozzle20to provide a certain propulsive thrust. The high-pressure turbine17drives the high-pressure compressor15by way of a suitable connecting shaft27, which is also referred to as the core shaft. The fan23generally provides the majority of the propulsion force. The epicyclic gearbox30is a reduction gearbox.

An exemplary arrangement for a geared-fan gas turbine engine10is shown inFIG.2. The low-pressure turbine19(seeFIG.1) drives the shaft26, which is coupled to a sun gear28of the epicyclic gear arrangement30. Multiple planet gears32, which are coupled to one another by means of a planet carrier34, are situated radially outside the sun gear28and mesh with the latter, and are in each case disposed so as to be rotatable on carrier elements or planet pins42which are connected in a rotationally fixed manner to the planet carrier34and are shown in detail inFIG.3. The planet carrier34limits the planet gears32to orbiting about the sun gear28in a synchronous manner while enabling each planet gear32to rotate about its own axis on the planet pins42, which represent static axes. The planet carrier34is coupled by way of linkages36to the fan23so as to drive the rotation of the latter about the engine axis9. Radially to the outside of the planet gears32and meshing therewith is an annulus or ring gear38that is coupled, via linkages40, to a stationary support structure24.

It is noted that the terms “low-pressure turbine” and “low-pressure compressor” as used herein can be taken to mean the lowest pressure turbine stage and the lowest pressure compressor stage (that is to say not including the fan23) respectively and/or the turbine and compressor stages that are connected to one another by the connecting shaft26with the lowest rotational speed in the engine (that is to say not including the gearbox output shaft that drives the fan23). In some documents, the “low-pressure turbine” and the “low-pressure compressor” referred to herein may alternatively be known as the “intermediate-pressure turbine” and “intermediate-pressure compressor”. Where such alternative nomenclature is used, the fan23can be referred to as a first compression stage or lowest-pressure compression stage.

The epicyclic gearbox30is shown in greater detail by way of example inFIG.3. Each of the sun gear28, the planet gears32and the ring gear38comprise teeth about their periphery to mesh with the other gears. However, for clarity, only exemplary portions of the teeth are illustrated inFIG.3. Although four planet gears32are illustrated, it will be apparent to the person skilled in the art that more or fewer planet gears32may be provided within the scope of protection of the claimed invention. Practical applications of an epicyclic gearbox30generally comprise at least three planet gears32.

The epicyclic gearbox30illustrated by way of example inFIGS.2and3is of the planetary type, in which the planet carrier34is coupled to an output shaft via linkages36, wherein the ring gear38is fixed. However, any other suitable type of epicyclic gearbox30may be used. As a further example, the epicyclic gearbox30may be a star arrangement, in which the planet carrier34is held fixed, with the ring gear (or annulus)38allowed to rotate. In the case of such an arrangement, the fan23is driven by the ring gear38. As a further alternative example, the gearbox30can be a differential gearbox in which both the ring gear38and the planet carrier34are allowed to rotate.

The geometry of the gas turbine engine10, and components thereof, is or are defined using a conventional axis system which comprises an axial direction X (which is aligned with the axis of rotation9), a radial direction Y (in the direction from bottom to top inFIG.1), and a circumferential direction U (perpendicular to the view inFIG.1). The axial, radial and circumferential directions X, Y and U are mutually perpendicular.

FIG.4shows the planet pin42in isolation in a highly schematic side view, while the planet pin42inFIG.5is shown in a longitudinal sectional view. A first circular line42A1shown inFIG.4corresponds to the diameter of the planet pin42when the latter is substantially at the ambient temperature of the gas turbine engine10. In contrast, the further line42B1corresponds to the circumference of the planet pin42during the operation of the gas turbine engine10of a planetary gearbox30embodied in a conventional way. In addition, the arrow43indicates the main load direction of the friction bearing41between the planet gear32and the planet pin42.

The main load direction43corresponds to the direction of the resultant bearing force of the friction bearing41, which is composed of the bearing force component FD and the further bearing force component FF. The bearing force component FD in each case results from the torque applied to the planetary gearbox30. The further bearing force component FF results from the centrifugal force which acts on the planet gear32when the planet carrier34is rotating during the operation of the planetary gearbox.

If the planet carrier34is of non-rotatable design, the main load direction43of the friction bearing41corresponds substantially to the direction of bearing force component FD since there is then no centrifugal force acting on the planet gear32. In addition, the direction of rotation of the planet gear32is indicated inFIG.4by the reference sign44.

Bearing force component FD encloses an angle phi equal to 90°, in the direction of rotation44of the planet gear32, with the radial direction of extent of the planet carrier34, which is the same as the radial direction y inFIG.4and passes through the center of the planet pin42and the radially outer point45. Bearing force component FF encloses an angle phi equal to 180°, in the direction of rotation44of the planet gear32, with the radial direction of extent of the planet carrier34.

When the planet carrier34is of rotatable design, the angular value of the angle phi which the main load direction43encloses with the radial direction of the planet carrier34is in a range of from 110° to 180°, depending on the operating state.

During the operation of the gas turbine engine10, the outside diameter of the planet pin42on the line42B1increases to a greater and greater extent in the direction of rotation44of the planet gear32, starting from a radially outer point45on an outer side46of the planet pin42. In the region of the planet pin42which surrounds the main load direction43at the circumference, the outside diameter of the planet pin42differs to a substantially greater extent from the circular line42A than at the radially outer point45on the outer side46of the planet pin42. This results from the fact that the non-rotating planet pin42, which is connected to the planet carrier34in a manner precluding relative rotation, is subject to the greatest heat input in the region of the main load direction43. This is the case because a bearing clearance63of the friction bearing41between an outer side46of the planet pin42and an inner side64of the planet gear32is at its smallest here owing to the acting load.

In contrast, the rotating planet gear32does not have locally limited heating corresponding to the planet pin42on account of the rotation and thermal inertia. For this reason, the inside diameter of the planet gear32expands uniformly in the circumferential direction as the operating temperature of the planetary gearbox30increases.

Owing to the different expansion behavior of the planet pin42and the planet gear32, the height of the bearing clearance63of the friction bearing41is reduced to an even extent in the main load zone extending in the circumferential direction U about the main load direction43. In the region of the main load zone of the friction bearing41and especially in the planet pin42, this results in very high operating temperatures in a locally limited area. These high operating temperatures prejudice a load-bearing capability and a service life of the friction bearing41to an unwanted extent.

FIG.5shows a longitudinal sectional view of the planet pin42along a section line V-V denoted more specifically inFIG.4. From the illustration according toFIG.5, it is evident that the planet pin42at relatively high operating temperatures expands to a greater extent centrically than in the region of its ends.

A highly simplified three-dimensional isolated illustration of a first embodiment of one of the planet pins42of the planetary gearbox30according toFIG.3is shown inFIG.6The planet pin42in the region of the external side46thereof is embodied with an oil feed pocket47. The planet pins42are in each case mounted in the planet carrier34so that the oil feed pockets47in the circumferential direction U of the planet pin42are in any case disposed outside the highly loaded region of the friction bearing41. The oil feed pocket47here is embodied as a machined recess or cut-out on the external side46of the planet pin42.

One line48, of which the port region49is disposed so as to be in the center of the friction bearing41in the axial direction X of the friction bearing41, opens into the oil feed pocket47. Additionally, the port region49in the circumferential direction U and in the axial direction X is disposed so as to be centric in the oil feed pocket47, the latter here being embodied so as to be substantially rectangular. The oil feed pocket47in the axial direction X of the friction bearing41here extends across a larger region of the external side46of the planet pin42than in the circumferential direction U.

Presently, the oil feed pocket47is provided in the region of the radially outer point45of the planet pin42and hence also of the friction bearing41. In this way, in the circumferential direction U of the planet pin42, the oil feed pocket47is disposed in a region of the friction bearing41which is subject to low loads. As a result, it is guaranteed the oil fed into the oil feed pocket47by way of the line48enters a bearing clearance51of the friction bearing41in the desired manner during the rotation of the planet gear32.

Depending on the respective specific application, the highly loaded region of the friction bearing41may be present in a circumferential region of the friction bearing41that, conjointly with the radial direction Y of the planet carrier34in the rotation direction44of the planet gear42, this corresponding to the main rotation direction of the planet gear32, encloses angular values phi in a range from 120° to 225°, preferably from 120° to 200°. The oil feed pocket47can be disposed outside a circumferential region of the friction bearing41that, conjointly with the radial direction Y of the planet carrier34in the rotation direction44of the planet gear32, encloses angular values phi in a range from 90° to 190°, preferably from 30° to 210°. It is guaranteed as a result that the oil feed pocket47is disposed outside a highly loaded region of the friction bearing41and that oil is able to be introduced into the bearing clearance51between the planet gear32and the planet gear42with little complexity

FIG.7shows a sectional view of an embodiment of the planetary gearbox30along a section line VII-VII which is denoted more specifically inFIG.3and is configured having the planet pin42embodied according toFIG.6. The planet carrier gear34of the planetary gearbox30comprises two side plates34A and34B spaced apart in the axial direction X. The planet pin42is disposed non-rotatably at the ends in respective holes50A and50B in the side plates34A and34B of the planet carrier34.

Additionally,FIG.8toFIG.12show in each case a cross-section view of different embodiments of the planetary gearbox30along a section line VIII-VIII which is denoted more specifically inFIG.7and of which the planet pin42is in each case configured to the extent described in the context ofFIG.6and which each differ substantially only in the region of the line48.

Pressurized oil from an oil supply unit52is directed into a supply line53which runs substantially in the axial direction in the planet pin42and is connected to the line48. The supply line53here is embodied as a blind bore.

The oil supply unit52and a flow cross section of the line53, as well as a flow cross section of the line48, are specified or mutually adapted in such a manner that, during operation of the planetary gearbox30, a ratio between the impulse by way of which the oil from the line48is directed into the bearing clearance51and the impulse of the oil which adheres to the internal side54of the planet gear32is at least 5×10−3. The impulse of the oil directed in here corresponds to the product of the square of the inflow rate of the oil into the oil feed pocket47, preferably in the port region49of the line48, and the density of this oil. Moreover, the impulse of the oil that adheres to the internal side54of the planet gear32corresponds to the product of the square of the velocity of the oil adhering to the second component, or on the planet gear32, respectively, and the density of the oil. The velocity of the adhering oil here is substantially equal to the rotating speed of the internal side54of the planet gear32.

The fed oil, or lubricant, respectively, is pressurized outside the bearing clearance51, in the region of the oil supply unit52, and thereafter, by means of a correspondingly small flow cross section, intensely accelerated in the region of the line48, or in the port region49, i.e. in the inlet to the oil feed pocket47. In the region of the oil feed pocket47, the accelerated oil meets hot dragged lubricant as well as the hot, rotating shell of the friction bearing41, this presently being the internal side54of the planet gear32. It is achieved as a result that the dragged lubricant, or oil, respectively is displaced laterally out of the bearing clearance51and squeezed out of the bearing clearance51. This leads to the cold fed oil primarily remaining in the axial center of the friction bearing41and being dragged into the tightest lubrication clearance, or into the highly loaded region of the friction bearing41, respectively, in which the radial height of the bearing clearance51is smallest.

In the embodiment of the planetary gearbox30shown inFIG.8, the profile of the line48, conjointly with the axial direction X of the bearing clearance51, encloses an angle α. The angle α here varies as a function of the respective specific application, so as to make available an ideally high cooling performance in the region of the friction bearing41.

The angle α here is provided in such a manner that the oil from the line48, as a function of the respective specific application, is guided into the bearing clearance51and in the direction of the internal side54of the planet gear32at angles α of approximately 5° to 60° in relation to the radial direction Y of the bearing clearance51and in the main rotation direction of the planet gear32, which is denoted more specifically by the arrow HR inFIG.8. Positive cooling of the highly loaded region of the friction bearing41, and thus an improved load bearing capability of the friction bearing41, are achieved as a result.

FIG.9shows an illustration, corresponding to that ofFIG.8, of the embodiment of the planetary gearbox30according toFIG.8, wherein a height of the bearing clearance51in the circumferential direction U inFIG.9is not illustrated true to scale. Additionally,FIG.9shows different temperature zones51A to51E of the lubricant, or of the oil, respectively, in the bearing clearance, said temperature zones51A to51E extending in the radial direction Y as well as in the circumferential direction U. Moreover, the friction bearing41in the axial direction X of the friction bearing41also has a temperature profile across the bearing width, said temperature profile to be discussed in more detail later in the description pertaining toFIG.21.

The temperature zone51A of the bearing clearance51is characterized by the lowest temperature of the oil in the bearing clearance51. The temperature zone51A here, from the port region49of the line48, initially extends obliquely through the bearing clearance51in the direction of the internal side54of the planet gear32. This first region of the temperature zone51A is created by the oil jet which exits the port region49of the line48at the angle α. Where the oil jet impacts the internal side54of the planet gear32, dragged oil is cooled by the oil being directed into the bearing clearance51. A temperature zone51B of the bearing clearance51in which the highest operating temperature of the oil is present, this being equal to the temperature of the oil which in the bearing clearance51is dragged from the tightest bearing clearance in the circumferential direction U, terminates in the circumferential direction U ahead of that region where the oil directed in impacts the internal side54of the planet gear.

By virtue of the oil directed into the bearing clearance51by way of the corresponding impulse, the cool fresh oil keeps adhering to the internal side54of the planet gear32, and in the circumferential direction U is dragged from the planet gear32in the direction of the highly loaded region of the friction bearing41on the external circumference of the bearing clearance51. A third temperature zone51C is formed between the zone51A and the external side46of the planet pin42, the oil in the region of said third temperature zone51C having a somewhat higher temperature than in the zone51A. The zone51C, from the oil jet, or from the region of the zone51A that penetrates the bearing clearance51at the angle α, extends to the highly loaded region of the friction bearing41, which here is present about the main load direction43. The oil in the highly loaded zone, in which the radial height of the bearing clearance51is the smallest, is heated by virtue of the shear load. Upstream of the highly loaded region of the friction bearing41, the clearance height of the bearing clearance51steadily converges up to the highly loaded region from the oil feed pocket47.

In a circumferential region of the bearing clearance51, which follows the highly loaded region of the friction bearing41in the circumferential direction U, or in the main rotation direction HR of the planet gear32, respectively, the clearance height of the bearing clearance51diverges, or the radial clearance height of the bearing clearance51steadily increases again in the direction of the oil feed pocket47, respectively. Upon leaving the highly loaded region of the friction bearing41, by virtue of the centrifugal force that engages on the oil during the operation, oil adheres to the internal side54of the planet gear32to the same degree as the fresh oil previously directed into the bearing clearance51and is entrained in the circumferential direction U, or in the main rotation direction HR of the planet gear32, respectively, in the direction of the oil feed pocket47. A further temperature zone51D of the bearing clearance51, within which the bearing clearance51is not completely filled with oil, is present between the temperature zone51B and the external side46of the planet pin42. The regions of the temperature zone51D in which oil is present in the form of oil droplets are denoted more specifically by the reference sign51DF inFIG.9. The lubricant regions51DF of the zone51D have an insignificantly lower operating temperature than the dragged oil in the temperature zone51B.

Additionally, in the main rotation direction HR of the planet gear32and radially within the zone51B, a further zone51E is established between the zone51D and the zone51A, said further zone51E being completely filled with oil and the oil in the region of said further zone51E having an operating temperature which corresponds substantially to the operating temperature of the oil in the zone51C. The operating temperature of the lubricant in the zone51E, which is lower in comparison to those in the zones51B and the lubricant regions51DF of the zone51D, is again established by virtue of the volumetric flow of oil directed from the line48into the bearing clearance41.

The temperature profile of the lubricant, or of the oil, respectively, present as a result of the different temperature zones51A to51E in the circumferential direction of the friction bearing41, has a positive effect on the load bearing capability of the friction bearing41. This results from the fact that improved cooling and an improved displacement of the dragged warm oil in the zone51B is achieved on account of the oil being fed by way of the correspondingly strong impulse and the oil being directed in obliquely in relation to the radial direction Y and in the main rotation direction HR of the planet gear32in relation to the planet pin42.

FIG.10shows an illustration, corresponding to that ofFIG.8, of a further exemplary embodiment of the planetary gearbox30, in which the line48, conjointly with the radial direction Y of the planetary gearbox30, encloses an angle β which as a function of the respective specific application, or specific load, respectively, is conceived for positive cooling and a positive displacement of dragged warm oil from the bearing clearance51of the friction bearing41. In principle, the angle β is chosen so that the discharge direction of the oil from the line48, conjointly with the radial direction Y of the bearing clearance51and counter to the main rotation direction HR of the planet gear32in relation to the planet pin42, encloses an angle β of approximately 5° to 20°.

FIG.11shows an illustration, corresponding to that ofFIG.9, having the temperature zones51A to51E in the bearing clearance51, said temperature zones51A to51E being established by virtue of the oblique introduction, described in relation toFIG.10, of the oil from the line48into the bearing clearance51. It is derived from a comparison of the illustrations according toFIG.9andFIG.11that the temperature zones51A and51C in the planetary gearbox30according toFIG.10extend across a larger circumferential region of the friction bearing41, or of the bearing clearance51, respectively, than the temperature zones51A and51C of the bearing clearance51of the planetary gearbox30according toFIG.9. In the embodiment of the planetary gearbox30according toFIG.10, the temperature zone51E in the circumferential direction U simultaneously extends across a smaller angular range, or circumferential region, respectively, of the bearing clearance51than the temperature zone51E of the friction bearing41according toFIG.8orFIG.9, respectively.

FIG.12shows a highly schematic three-dimensional illustration of the planet pin42of further embodiments of the planetary gearbox30. The planet pin42is embodied with the oil feed pocket47and the line48. The line48here, to the degree described in more detail in the context ofFIG.13toFIG.19, comprises two line portions48A,48B which adjoin one another in the feed direction Z14or Z16, respectively, of the oil into the oil feed pocket47. The flow cross section of the first line portion48A, which is connected directly to the supply line53, is smaller than the flow cross section of the second line portion48B, which opens into the oil feed pocket47.

The flow cross sections of the two line portions48A and48B are mutually disposed so as to be offset in the circumferential direction U, or in the main rotation direction HR of the planet gear32, respectively. In the exemplary embodiment illustrated in more detail inFIG.13,FIG.14andFIG.18, the flow cross section of the line48for the oil, proceeding from the first line portion48A in the direction of the second line portion48B, here increases more in the circumferential direction U of the bearing clearance51and counter to the main rotation direction HR of the second component, or of the planet gear32, respectively, than in the main rotation direction HR of the planet gear32.

As opposed thereto, in the exemplary embodiment of the planetary gearbox30illustrated inFIG.15,FIG.16andFIG.19, the flow cross section of the line48for the oil, proceeding from the first line portion48A in the direction of the second line portion48B, increases more in the circumferential direction U of the bearing clearance51and in the main direction HR of the planet gear32in relation to the friction bearing41than counter to the main rotation direction HR of the planet gear32.

The eccentric arrangement of the line regions48A and48B of the line48according toFIG.12, which causes the jet of the volumetric flow of oil to be guided eccentrically in the line48, in relation to the radial direction X deflects the volumetric flow of oil in the rotation direction HR of the planet gear32and in the direction of the internal side54of the planet gear32. The deflection of the volumetric flow of oil in the rotation direction, or in the main rotation direction HR of the planet gear32, respectively, exploits the so-called Coandă effect. As a result, the freshly supplied lubricant, or oil, respectively, is transported in the direction of the tightest lubrication clearance, or the main load zone of the friction bearing41, respectively, so as to be more centric in the friction bearing41. Since the supporting region arises primarily in the axial center of the friction bearing41, the fresh lubricant can act in a more targeted manner here.FIG.14in an enlarged illustration shows a region XIV, indicated more specifically inFIG.13, and the eccentric mutual arrangement of the two line portions48A and48B, as well as the feed direction Z14of the oil from the line48into the bearing clearance51.

FIG.15andFIG.16show the eccentric arrangement of the two line regions48A and48B in the rotation direction HR of the planet gear32, said eccentric arrangement, by virtue of the Coandă effect likewise acting as a result, according to the feed direction Z16causing an oblique discharge of the volumetric flow of oil from the line48counter to the rotation direction HR and in the direction of the internal side54of the planet gear32.

FIG.17shows a longitudinal sectional view of the variants of the planetary gearbox30shown inFIGS.13and15, along a section line XVII-XVII denoted more specifically in each ofFIG.13andFIG.15.

FIGS.18and19each show an illustration, corresponding to that ofFIG.9, of the embodiments of the planetary gearbox30according toFIG.13orFIG.15, respectively. The oblique introduction of the volumetric flow of oil into the bearing clearance51in relation to the radial direction Y of the planetary gearbox30, or of the friction bearing41, respectively, again leads to the different lubricant zones, or temperature zones51A to51E, respectively, being established in the bearing clearance51in circumferential direction U and in the rotation direction HR of the planet gear42.

It is derived from a comparison of the illustration according toFIG.9orFIG.11, respectively, and the illustrations according toFIG.18orFIG.19, respectively, that an obliquely running line48as well as the eccentric mutual arrangement of the line portions48A and48B, in conjunction with a correspondingly strong impulse ratio of the oil, has the effect of improving the load bearing capability of the friction bearing41in comparison to known friction bearing embodiments.

In further embodiments of the planetary gearbox30it can also be provided that at least one of the lines48,55, or48,55,57, or67to70, respectively, is embodied with line portions that are embodied so as to be mutually eccentric, as well as with a profile that is oblique in relation to the radial direction Y.

FIG.20shows a developed view of a bearing clearance100of a conventionally embodied friction bearing, in which oil in the region of an oil feed pocket is directed into the bearing clearance substantially in the radial direction Y and by way of an insufficient impulse ratio. In the operation, different temperature zones100A to100H are established in the circumferential direction U and in the rotation direction, or in the main rotation direction HR of the rotatable component of the friction bearing, respectively, in the bearing clearance100. The temperature zones100A to100H are established by virtue of the insufficient supply of lubricant into the bearing clearance100. Moreover, a temperature scale for the temperature zones100A to100H is indicated below the illustration of the developed view of the bearing clearance inFIG.20. The temperature in the zone100A is the lowest and corresponds substantially to the temperature at which the oil is fed into the bearing clearance100. Moreover, the temperature in the temperature zone100H of the lubricant is the highest and corresponds substantially to the temperature in the bearing clearance100in the tightest lubrication clearance, or to the temperature of the dragged oil, respectively.

A circumferential region U101of the bearing clearance100presently comprises the region of the bearing clearance in which the oil feed pocket of the friction bearing is provided and in which mixing takes place between the oil dragged into the bearing clearance100and the fed cool oil. A second circumferential region U102of the bearing clearance100, in which the bearing clearance, or the height of the latter in the rotation direction of the rotatable component of the friction bearing, respectively converges and further mixing of the hot dragged lubricant and the cold fed lubricant takes place, adjoins the circumferential region U101. A temperature zone100C, which is central in the axial direction X of the friction bearing, is disposed between two axially outer temperature zones100D in the circumferential region U102, wherein the temperature in the temperature zone100C is higher than in the lateral temperature zones100D of the bearing clearance100.

By virtue of the decreasing clearance height of the bearing clearance100, the temperature in the bearing clearance100increases already in the circumferential region U102, which is why the temperature in a further temperature zone100E, embodied so as to be at least approximately arcuate, is higher than in the temperature zones100C and100D. From the circumferential region U102, the temperature zone100E extends across the further circumferential regions U103, U104into the circumferential region U101. Further temperature zones100F,100G and the centric temperature zone100H are provided in the circumferential direction U, or in the rotation direction HR of the rotatable component, as well as in the axial direction X, or in the direction of the bearing center of the friction bearing, or of the bearing clearance100, respectively, within the temperature zone100E. The temperature of the oil here increases in each case from the temperature zone100E in the direction of the temperature zone100H.

The circumferential region U103comprises the area, or the circumferential region, respectively, of the bearing clearance100in which the tightest lubrication clearance, or the smallest lubrication clearance height, respectively, is present and in which significant heating of the lubricant takes places in the bearing clearance100. The circumferential region U103is adjoined by the further circumferential region U103in which the height of the lubrication clearance increases again in the circumferential direction U, or in the main rotation direction HR of the rotatable component, respectively. This region corresponds to the partially filled, diverging clearance region of the bearing clearance100described in the context ofFIG.9andFIG.11. The temperature zone100F, disposed between the temperature zone100E and the inner temperature zone100H, and also the temperature zone100G in the circumferential region U104have a substantially consistent profile, or a substantially consistent width, respectively, in the circumferential direction U as well as in the axial direction X. The temperature profile of the bearing clearance100described in the context ofFIG.20, in particular by virtue of the high temperature of the lubricant in the temperature zone100H, has a disadvantageous effect on the load bearing capability of a friction bearing. Additionally, such a friction bearing has to be fed a high quantity of lubricant in order to avoid undesirably high bearing temperatures.

FIG.21shows an illustration, corresponding to that ofFIG.20, of the bearing clearance51of the friction bearing41of the planetary gearbox30, having on the circumference different bearing clearance portions U511to U512and different temperature zones51A to51B. In principle, the temperature zones51A and51B are established in the bearing clearance51in all afore-described embodiments of the planetary gearbox30. The temperature zone51A here has substantially the same temperature level as the temperature zone100A of the bearing clearance100. It is apparent when comparing the two illustrations according toFIG.21andFIG.20that the cool temperature zone51A extends across a substantially larger circumferential region of the bearing clearance51than is the case in the temperature zone100A of the bearing clearance100.

A region AUF, which identifies the impact region of the jet of the volumetric flow of oil from the line48on the internal side54of the planet gear32is denoted in the circumferential region U511of the bearing clearance51. It can furthermore be derived from the illustration according toFIG.21that the afore-described oil feed into the bearing clearance51has the effect of cooling and displacing the dragged oil in the bearing clearance51in the desired manner. Additionally, as a result of the impulse-rich oil feed into the bearing clearance51, directed in each case in the rotation direction or counter to the rotation direction HR of the planet gear32, an overall reduction of the temperature level in the bearing clearance51in the circumferential direction U as well as in the axial direction X is achieved in comparison to the friction bearing of which the temperature profile is shown inFIG.20.

The outer temperature zones51A2here have substantially the same temperature level as the temperature zone100E in the bearing clearance100. The improved cooling of the friction bearing41manifests itself most significantly in that the inner temperature zone51B has a lower temperature level than the central temperature zone100H of the bearing clearance100. In the exemplary embodiment in focus, the temperature level of the temperature zone51B corresponds to the temperature level of the temperature zone100G of the bearing clearance100. Additionally, the oil in the temperature zone51B1has the temperature level of the temperature zone100F.

The circumferential region U511of the bearing clearance51, besides the jet impact region AUF, also comprises a part of the bearing clearance region in the circumferential direction U in which the bearing clearance51, or the height thereof, respectively, already converges in the direction of the highly loaded region of the friction bearing41, and in which mixing of the hot dragged lubricant with cold fed lubricant takes place. The mixing of the cold lubricant with the dragged hot lubricant also continues in the circumferential region U512of the bearing clearance51, into which the coldest temperature zone51A extends to the degree illustrated. The circumferential region U512is adjoined by the circumferential region U513which corresponds substantially to the circumferential region U103of the bearing clearance100and in the circumferential direction U comprises the area of the bearing clearance51in which the tightest lubrication clearance is disposed and in which significant heating of the lubricant takes place. In the main rotation direction HR of the planet gear32, the circumferential region U513is adjoined by the circumferential region U514of the bearing clearance51, the latter corresponding substantially to the circumferential region U104of the bearing clearance100and the partially filled, diverging clearance region being present therein.

FIG.22shows a plan view of the oil feed pocket47of the friction bearing41of a further embodiment of the planetary gearbox30, in which—besides the line48—a further line55opens into the oil feed pocket47and thus into the bearing clearance51. A port region56of the further line55in the axial direction X of the friction bearing41is disposed on the same circumferential region as the port region49of the line48. In the exemplary embodiment of the planetary gearbox30shown inFIG.22, the lines48and55open into the oil feed pocket47so as to be centric in the axial direction X. The port region56is disposed in the oil feed pocket47so as to be spaced apart from the port region49in the circumferential direction U of the bearing clearance51and in the main rotation direction HR of the planet gear42.

As a result of this mutual arrangement of the two port regions56and49, a temperature profile which corresponds substantially to the temperature profile described in more detail in the context ofFIG.21is established in the bearing clearance51. In order to achieve further improved cooling and lubricating of the friction bearing41, the lines48and55, as explained in more detail above, can in each case be embodied so as run obliquely or with line portions that are disposed so as to be mutually eccentric. In this instance, the oil from the lines48and55is in each case able to be directed into the bearing clearance51, in the manner described in more detail above, in the main rotation direction HR or counter to the main rotation direction HR, and preferably by way of a correspondingly strong impulse.

In further embodiments it is additionally possible for the port region56to be disposed in the oil feed pocket47so as also to be offset from the port region49in the axial direction X of the friction bearing41. Good cooling and lubricating of the friction bearing41here is achieved when the port region56of the line55is disposed within a sector S of which the center SM lies in the port region49of the line48and which encloses an angle γ of approximately 120°.

FIG.23shows an illustration, corresponding to that ofFIG.22, of a further exemplary embodiment of the planetary gearbox30in which, besides the line48, a second line55and a third line57open into the oil feed pocket47. All the lines48,55and57can be connected to the supply line53, or, to the degree described later in the context ofFIG.33toFIG.37, be impinged with oil from different oil supply units.

Port regions56and58of the lines55and57are spaced apart from the port region49of the line48in the circumferential direction U of the friction bearing41as well as in the main rotation direction HR of the planet gear32and also in the axial direction X. The port regions56and58of the lines55and57here, in terms of the port region49of the line48, in the axial direction X are disposed in the oil feed pocket47in such a manner that the port region49in the axial direction X is disposed between the port regions56and58of the lines55and57. In this way, the port regions49,56and58of the lines48,55and57are present in a so-called mutual A arrangement which enables efficient cooling of the friction bearing41and, in comparison to known friction bearing embodiments, has the effect of reducing the temperature level in the friction bearing41. The port regions56and58of the lines55and57are disposed in a sector S of which the center SM lies in the port region49of the line48and of which the opening angle γ corresponds to approximately 120°.

Shown to a highly simplified degree inFIG.24is the oil flow in the bearing clearance51in the region of the oil feed pocket47, in which the three lines48,55and57, or the port regions49,56and58thereof, respectively, are mutually disposed to the degree described in the context ofFIG.23, and by way of which oil is in each case directed into the bearing clearance47counter to the rotation direction HR of the planet gear32. The drawn lines P59and P60inFIG.24here represent the flow profile of dragged oil in the bearing clearance51. The flow of the dragged oil in the circumferential direction U, or in the rotation direction HR, respectively, ahead of the oil feed pocket47runs substantially in the circumferential direction U. When flooding the oil feed pocket47, the dragged oil, by the oil which by way of the lines48,55and57is directed into the oil feed pocket47, in the axial direction X—corresponding to the drawn lines P59and P60—is increasingly displaced outward in the direction of the axially outer bearing sides of the friction bearing41and there ultimately squeezed out of the bearing clearance51.

The displacement of the dragged oil in the bearing clearance51arises in particular when the cold oil from the lines48,55and57is directed by way of a strong impulse into the bearing clearance51in the region of the oil feed pocket47. By virtue of the temperature-related density differential between the fed cold oil and the dragged hot oil, only minor mixing of the hot dragged oil with the cold freshly fed oil takes place, as a result of which an increased load bearing capability of the friction bearing41is achieved.

Furthermore, the centric feeding of fresh oil ensures adequate cooling and lubricating of the highly loaded region in the circumferential region. The main flow direction of the freshly fed oil from the line48is indicated by the drawn lines P61and P62inFIG.24. Additionally, the drawn lines P63and P64show the main flow direction of the oil which is directed into the oil feed pocket47by way of the line55. Furthermore, the drawn lines P65and P66show the main flow direction of the oil which is directed into the oil feed pocket47by way of the line57.

FIG.24ashows a schematic two-dimensional view of a region of the planet pin42in which the oil feed pocket47having the port regions49,56and58of the first line48, of the second line55and of the third line57is provided. A surface region46A of the external side46of the planet pin42, in which the port regions49to58of the lines48to57are disposed as a function of the specific application, is denoted more specifically about the port regions49to58. The surface region46A here is configured so as to be trapezoidal, wherein the two parallel sides46A1,46A2of the surface region46A run in the axial direction X of the friction bearing41. The oblique sides46A3,46A4of the surface region46A that run between the parallel sides46A1,46A2of the surface region46A connect the shorter parallel side46A1to the longer parallel side46A2that in the circumferential direction X and in the main rotation direction HR follows the shorter parallel side46A1. The spacing between the longer side46A2and the shorter side46A1in the circumferential direction U and in the main rotation direction HR of the planet gear is 10% of the entire bearing circumference of the friction bearing41.

The surface region46A in the axial direction X is provided in the bearing center of the friction bearing41. The width, or the axial length of the shorter parallel side46A1, respectively, is equal to 25% of the bearing width L41of the friction bearing41. The length of the longer parallel side46A2corresponds to 50% of the bearing width L41of the friction bearing41.

FIG.24bshows a simplified illustration of the port regions49,57and59of the first line48, of the second line55and of the third line57, said port regions being based on an underlying grid pattern150. The spacings between the intersection points of the grid lines of the grid pattern160here are equal to the diameter of the port region49of the first line48. It can be derived from the illustration according toFIG.24bthat the center of the port region49of the first line48in the circumferential direction, or in the main rotation direction HR of the planet gear32, respectively is spaced apart from the centers of the port regions56and58of the lines55and57by four times the diameter of the port region49of the first line48. This value of the spacing in the circumferential direction U represents the maximum when four times the diameter of the port region49of the first line is less than one tenth of the entire bearing circumference of the friction bearing41. In other instances, the tenth part of the entire circumference of the friction bearing41is provided as the maximum value for the maximum spacing in the circumferential direction between the center of the port region49and the centers of the port regions56and58.

Additionally, the center of the port region49in the variant of arrangement of the port regions49to57shown inFIG.24bin the axial direction X is in each case spaced apart from the port regions56and58by four times the diameter of the port region49. These axial spacings again each represent maximum values within which the friction bearing41is ideally impinged with oil in order to achieve an ideally high load bearing capability of the friction bearing41.

These values of the axial spacing of the centers of the port regions56and58from the port region49represent the maximum values when port regions56and58are disposed in the surface region46A. In other instances, half the bearing width of the friction bearing41is provided as the maximum value for the arrangement of the port regions56and58in order to guarantee intense cooling of the friction bearing41to the desired degree.

FIGS.25to27indicate further potential mutual arrangements of the port regions49,56and58of the lines48,55and57in the circumferential direction U and in the axial direction X. The mutual arrangements of the port regions49,56and58, and the spacings therebetween in the circumferential direction U and in the axial direction X, can vary as a function of the respective specific application in order to be able to cool the bearing clearance51, or the friction bearing41, as a function of the load. The port regions49,56and58here are in each case present in the afore-described A arrangement.

FIG.28toFIG.30each show illustrations, corresponding to that ofFIG.23, of further embodiments of the planetary gearbox30, in which four lines67to70open in each case into the oil feed pocket47, said four lines in each case being mutually spaced apart in the circumferential direction U, or in the rotation direction HR of the planet gear32, respectively, and additionally in the axial direction X of the friction bearing41.

In the exemplary embodiment illustrated inFIG.28, the port regions71and72of the lines67and68are disposed at the same height level in the circumferential direction U, while port regions73and74of the lines69and70are spaced apart from the port regions71,72of the lines67,68in the circumferential direction U, or in the rotation direction HR of the planet gear32, respectively. The port regions73,74of the lines69and70are disposed in a sector S of which the center SM presently lies between the port regions71,72of the lines67,68and which has an opening angle γ of approximately 120°.

The port regions71and72of the lines67and68in the exemplary embodiment of the planetary gearbox30illustrated inFIG.29are mutually spaced apart in the circumferential direction U as well as in the axial direction X. Additionally, the port regions73and74of the lines69and70are mutually spaced apart in the circumferential direction U and in the rotation direction HR of the planet gear32, and additionally also in the axial direction X. This also applies to the embodiment of the planetary gearbox30illustrated inFIG.30.

In all embodiments of the planetary gearbox30illustrated inFIG.28toFIG.30, the axial spacings between the port regions71and72of the lines67and68, as well as between the port regions73and74of the lines69and70and the axial spacings of the port regions71to74of the lines67to70, are mutually provided so that the port regions67and68in the axial direction each lie between the port regions73and74of the lines69and70. This again results in a positive displacement of the dragged hot oil, to the degree described in the context ofFIG.24, in the outward axial direction X by the cool oil which is in each case directed in by way of the lines67to74. As a result of the dragged oil being displaced from the bearing clearance51, a desirably low temperature level in the bearing clearance51of the friction bearing41is achieved, and adequate cooling and lubricating of the highly loaded region of the friction bearing41is achieved, as a result of which the friction bearing41has a sufficiently high load bearing capability.

FIG.31shows an illustration, corresponding to that ofFIG.28, of an oil feed pocket470of a friction bearing known from the prior art. Four lines670,680,690and700likewise open into the oil feed pocket470, the port regions710to740of said lines670,680,690and700being mutually positioned in a so-called V arrangement. The port regions710and720in the axial direction X of the oil feed pocket470here are farther spaced apart from one another than the port regions730and740of the lines690and700are spaced apart from a rotatable component in the circumferential direction, or in the rotation direction HR of said rotatable component, respectively. The port regions730and740in the axial direction are disposed between the port regions710and720of the lines670and680. The main flow directions of the fresh oil that is directed from the lines670to740into the oil feed pocket470are indicated by the drawn lines P630, P640, P641, P642, P643, P644, P650and P660inFIG.32.

This mutual arrangement of the port regions710and740leads to the hot dragged oil, according to the drawn lines P590and P600illustrated inFIG.32, by the oil freshly directed into the oil feed pocket470being guided to an undesirable degree into the bearing center of the friction bearing. As a result, no displacement of the dragged oil in the direction of the external sides of the bearing takes place. Therefore, the temperature level in the bearing clearance470is not substantially reduced by feeding fresh cool oil.

FIG.33shows an embodiment of a planet pin42in which the three lines48,55and57are disposed in the oil feed pocket47and open into the latter to the degree described in the context ofFIG.23.FIG.34shows a cross-sectional view of an embodiment of the planetary gearbox30having the planet pin42according toFIG.33, in a cross-sectional view along a section line XXXIV-XXXIV denoted more specifically inFIG.33. Furthermore,FIG.35shows an illustration, corresponding to that ofFIG.34, of the planetary gearbox30along a section line XXXV-XXXV denoted more specifically inFIG.33. Additionally illustrated inFIG.36is a longitudinal sectional view of the planetary gearbox30along a section line XXXVI-XXXVI denoted more specifically inFIG.34.FIG.37shows an illustration, corresponding to that ofFIG.36, of the planetary gearbox along a section line XXXVII-XXXVII denoted more specifically inFIG.35.

It is apparent from the illustrations according toFIG.33toFIG.37that the line48to the extent described in the context ofFIG.7, is supplied with pressurized oil from the oil supply unit52by way of the line53. Additionally, the lines55and57are impinged with pressurized oil from a further oil supply unit81by way of a further line80which runs in the axial direction X in the planet pin42. As a result of the separate embodiment of the oil supply units52and81there is the possibility to direct oil at a lower temperature into the bearing clearance51of the friction bearing41by way of the line48than by way of the lines55and57. Moreover, the friction bearing41can continue to be supplied with oil by way of the respective other oil supply unit81or52, even in the event of a functional failure of the oil supply unit52or of the oil supply unit81.

The fresh volumetric flows of oil which are directed eccentrically into the bearing clearance51by way of the lines55and57, and of which the temperature is higher than the temperature of the volumetric flow of oil that by way of the line48is directed into the bearing clearance51axially between the volumetric flows of oil from the lines55and57, counteract any proliferation of the cooler and centrically fed volumetric flow of oil in the axial direction X of the bearing clearance. The lubricant from the line48, in the manner illustrated inFIG.38, is kept in the axial center of the friction bearing41by being blocked by the warmer lubricant flows from the lines55and57.

As a result of the two mutually separated oil supplies into the oil feed pocket47, the latter being characterized by a feed of cool oil in the axial center of the oil feed pocket47and by eccentric feeds of warmer lubricant, the tightest lubrication clearance of the friction bearing41is again cooled to the desired degree. A high load bearing capability of the friction bearing41is also achieved by the viscosity of the oil in the bearing clearance51, said viscosity being a result of the positive cooling. Furthermore, the quantity of the fresh lubricant used can also be reduced in comparison to conventionally embodied friction bearings. As a result, the cooling circuit of the high performance gearbox30can be designed more efficiently and smaller.

FIG.38shows an illustration, corresponding to that ofFIG.21, of the bearing clearance51of the planetary gearbox30according toFIG.33toFIG.37. By virtue of the oil that is directed at different oil temperatures into the bearing clearance51, different temperature zones90A to90H, which extend in the circumferential direction U and in the axial direction X of the friction bearing41, are established in the bearing clearance51in the operation of the planetary gearbox30. The bearing clearance51in the circumferential direction U as well as in the main rotation direction HR of the planet gear32here is again sub-divided into a plurality of circumferential regions U511to U514. The circumferential regions U511to U514correspond substantially to the circumferential regions U511to U514of the bearing clearance51that have been specified in more detail in the context ofFIG.21.

The temperature zone90A in the bearing clearance51is established in the region in which the cooler oil is directed into the oil feed pocket47by way of the line48. The further temperature zones90B and90C in which the temperature of the oil is higher than the temperature of the oil in the temperature zone90A are in each case illustrated next to the temperature zone90A in the axial direction X. The temperatures of the oil in the temperature zones90A and90B and90C here correspond in each case to the feed temperatures of the oil from the line48, or from the lines55and57, respectively. As a result of the volumetric flows of oil controlled to different temperatures that from the lines48, or55and57, respectively, are directed into the oil feed pocket47in or counter to the rotation direction HR, the further temperature zones90A1,90B1and90C1are established in the rotation direction HR after the temperature zones90A and90B and90C in the bearing clearance51. The temperature of the oil in the temperature zone90A1is higher than in the temperature zone90A, because the oil on the internal side54of the planet gear32is heated by the planet gear32as well as by the dragged oil in the bearing clearance51. The same applies to the temperature zones90B1and90C1in which the temperature level of the oil is higher than in the temperature zones90B and90C.

Further temperature zones90D and90E in which the oil temperature is again higher than in the temperature zones90B1and90C1are in each case established next to the temperature zones90B1and90C1. The reason for this is that oil in the axial direction X is pushed laterally out of the bearing clearance51in the temperature zones90D and90E. The oil that is pushed out has a lower temperature in comparison to the dragged oil. This is the case because the dragged oil has been cooled by the fresh cool oil which has been directed into the bearing clearance51by way of the lines48,55and57.

By virtue of the bearing clearance51that narrows on the circumference, or the converging bearing clearance51, respectively, and the increasing load on the friction bearing41, the temperature of the oil in the bearing clearance51, just before the transition between the circumferential regions U512and U513, increases across substantially the entire bearing width. The at least approximately arcuate temperature zone90F in which the oil has a higher temperature level than in the temperature zones90B1and90C1results from the temperature increase in the oil.

Once the oil reaches the circumferential region U513of the friction bearing41, in which the tightest lubrication clearance is present by virtue of the load engaging thereon, significant heating of the lubricant in the bearing clearance51arises again. This leads to two further temperature zones90G and90H being established in the axial direction as well as in the circumferential direction within the temperature zone90F. The temperature zone90G is formed between the temperature zone90F and the inner temperature zone90H in which the oil temperature is the highest.

In the circumferential region U514, in which the lubrication clearance, or the height of the bearing clearance51steadily increases again in the main rotation direction HR of the planet gear52, the oil temperature in the temperature zones90F to90H remains substantially the same. The circumferential region U514of the bearing clearance51here again comprises the afore-described region of the bearing clearance51which is only partially filled with oil. The circumferential region U514is then again adjoined by the circumferential region U511in which fresh and cool oil is again directed into the bearing clearance51by way of the lines48,55and57.

The port regions49,56and58, or71to74, respectively, of the lines48,55,57or67to70, respectively, depending on the respective specific application, can in each case have flow cross sections of different sizes. As a result, the oil can be directed into the oil feed pocket47and thus also into the bearing clearance51in the direction of the internal side54of the planet gear32by way of different impulses, so as to displace the dragged oil in the bearing clearance51in the outward axial direction X in the desired manner.

LIST OF REFERENCE SIGNS

9Main rotation axis10Gas turbine engine11Core12Air inlet14Low-pressure compressor15High-pressure compressor16Combustion device17High-pressure turbine18Bypass thrust nozzle19Low-pressure turbine20Core thrust nozzle21Engine nacelle22Bypass duct23Thrust fan24Support structure26Shaft, connecting shaft27Connecting shaft28Sun gear30Gearbox, planetary gearbox32Planet gear34Planet carrier34A,34B Side plates36Linkage38Ring gear40Linkage41Friction bearing42Planet pin42A,42B,42C Outside diameter of the planet pin43Arrow, main load direction44Direction of rotation of the planet gear45Radially outer point of the planet pin46External side of the planet pin46A Surface region of the external side46of the planet pin46A1,46A2Parallel sides of the surface region46A46A3,46A4Oblique sides of the surface region46A47Oil feed pocket48Line49Port region of the line4850A,50B Bores of the side walls34A,34B51Bearing clearance51A,51A1,51A2Temperature zones of the bearing clearance5151B,51B1Temperature zones of the bearing clearance5151C to51E Temperature zones of the bearing clearance5151DF Region of the temperature zone51D of the bearing clearance5152Oil supply unit53Supply line54Internal side of the planet gear55Further line, second line56Port regions of the line5557Third line58Port region of the third line67First line68Second line69Third line70Fourth line71Port region of the first line6772Port region of the second line6873Port region of the third line6974Port region of the line7080Line81Further oil supply unit90A,90A1Temperature zones of the bearing clearance5190B,90B1Temperature zones of the bearing clearance5190C,90C1Temperature zones of the bearing clearance5190E to90H Temperature zones of the bearing clearance51100A to100H Temperature zones of the bearing clearance100150Grid pattern470Oil feed pocket670First line680Second line690Third line700Fourth line710Port region of the first line670720Port region of the second line680730Port region of the third line690740Port region of the line700A Core air flowAUF Impact regionB Air flowFD Bearing force componentFF Bearing force componentHR Main rotation direction of the planet gearL41Bearing width of the friction bearing41phi AngleP59, P50Flow of dragged oilP61to P66Flow of fresh oilP590, P600Flow of dragged oilP630to660Flow of cool oilS SectorSM Center of the sectorU Circumferential directionU101to U104Circumferential region of the bearing clearance100U511to U514Circumferential region of the bearing clearance51X Axial directionY Radial directionZ14, Z16Feed directionα, β, γ Angle