阅读说明：本技术 齿轮箱组件 (Gear box assembly ) 是由 大卫·L·艾伦 于 2020-01-21 设计创作，主要内容包括：本发明公开了一种齿轮箱组件,所述齿轮箱组件包括：具有多个齿轮的齿轮箱、空气涡轮起动器和传送轴。所述传送轴具有与所述齿轮箱的齿轮接合的第一端部部分和被构造用于与所述涡轮引擎的芯轴可操作地连接的相对的第二端部部分。所述空气涡轮起动器在所述第一端部部分和所述第二端部部分之间与所述传送轴可操作地接合,以便能够由所述空气涡轮起动器旋转。(The invention discloses a gearbox assembly, comprising: a gearbox having a plurality of gears, an air turbine starter, and a transfer shaft. The transfer shaft has a first end portion engaged with a gear of the gearbox and an opposite second end portion configured for operable connection with a spindle of the turbine engine. The air turbine starter is operably engaged with the transfer shaft between the first end portion and the second end portion so as to be rotatable by the air turbine starter.)

1. A gearbox assembly for a gas turbine engine, the gearbox assembly comprising:

a gearbox having a plurality of gears;

an air turbine starter; and

a transfer shaft having a first end portion engaged with a gear of the gearbox and an opposing second end portion configured for operable connection with a spindle of the gas turbine engine, the air turbine starter being operably engaged with the transfer shaft between the first end portion and the second end portion so as to be rotatable by the air turbine starter.

2. The gearbox assembly of claim 1, wherein an axis of rotation of the air turbine starter is the same as or parallel to an axis of rotation of the transfer shaft.

3. The gearbox assembly of claim 1, wherein the transfer shaft extends through the air turbine starter from the first end to the second end.

4. The gearbox assembly of claim 1, wherein the air turbine starter includes an elongated cavity extending therethrough to receive the transfer shaft.

5. The gearbox assembly of claim 1, wherein the shuttle shaft is laterally offset from the air turbine starter and the air turbine starter operably engages the shuttle shaft via an eccentric shaft extending laterally between the air turbine starter and the shuttle shaft.

6. The gearbox assembly of claim 1, wherein the gears of the gearbox form a gear train extending transversely relative to the rotational axis of the transfer shaft.

7. The gearbox assembly of claim 6, wherein the gearbox includes a housing enclosing the gear train, the housing having first and second laterally extending sides spaced apart from either side of the gear train.

8. The gearbox assembly of claim 7, wherein the first and second sides of the housing include a plurality of mounting portions for mounting an engine accessory to the housing.

9. The gearbox assembly of claim 7, wherein the air turbine starter is mounted to the first side of the housing and another engine accessory is mounted to the second side of the housing.

10. The gearbox assembly of claim 9, wherein the another engine accessory is a variable frequency generator.

11. The gearbox assembly of claim 10, wherein the variable frequency generator is mounted directly opposite the air turbine starter.

12. The gearbox assembly of claim 1, wherein the air turbine starter includes a clutch for selectively engaging and disengaging the air turbine starter from the transfer shaft.

13. A gas turbine engine, the gas turbine engine comprising:

an engine core including a turbine, a compressor, and a spindle connecting the turbine to the compressor;

a gearbox assembly according to any one of the claims 1; and

an engine takeoff assembly arranged for transferring rotational motion between the spindle and the gearbox assembly.

14. The gas turbine engine of claim 13, wherein the engine takeoff assembly includes a radial shaft extending radially from the spindle.

15. An air turbine starter for a gas turbine engine, the air turbine starter comprising:

an air inlet;

a drive assembly extending through the air turbine starter between a first end configured for operable connection with a gearbox of the turbine engine and a second end portion for operable connection with a spindle of the turbine engine; and

a turbine rotor in fluid communication with the air inlet and operably connected to the drive assembly to rotate the drive assembly.

16. The air turbine starter of claim 15, wherein the transmission assembly includes a shaft or a plurality of coupled shafts extending through the air turbine starter.

17. The air turbine starter of claim 15, wherein the air inlet is annular and at least partially surrounds the first end portion or the second end portion.

Technical Field

The present disclosure relates to a gearbox assembly for an engine accessory including a gas turbine engine.

Background

Typically, an accessory gearbox of an aircraft gas turbine engine is mounted to a fan case of the turbine engine at a location below the engine.

The gearbox is connected to the engine core by a radial drive shaft (i.e. extending radially relative to an axially extending spindle of the engine core). In some arrangements, depending on the position of the accessory gearbox, the transfer gearbox may connect the radial drive shaft to an axially extending transfer shaft, which may in turn be connected to the accessory gearbox.

The engine core powers engine accessories mounted to the gearbox (from the engine core), such as auxiliary generators and pumps for hydraulic fluid, fuel, oil, etc. In addition to these accessories, the turbine starter may also be mounted to an accessory gearbox. The turbine starter may be used to initiate movement of the spindle via a gearbox and various transmission components (e.g., a transmission shaft, a radial shaft, etc.) that connect the gearbox to the spindle.

Accessory gearboxes generally include a gear train formed from spur gears. Turbine starters and other engine accessories are mounted on either side of the gear train and engage the gears to drive or be driven by the gears of the gear train. The gear train and engine accessories may occupy a significant amount of space outside the fan case, and may also have a significant overall weight.

Accordingly, there is a need to reduce the size and/or weight of an engine accessory gearbox.

Disclosure of Invention

The present disclosure provides a gearbox assembly, a gas turbine engine and an air turbine starter as set out in the appended claims.

In a first aspect, there is provided a gearbox assembly for a gas turbine engine, the gearbox assembly comprising: a gearbox having a plurality of gears; an air turbine starter; and a transfer shaft having a first end portion engaged with the gear of the gearbox and an opposing second end portion configured for operable connection with a spindle of the gas turbine engine, the air turbine starter being operably engaged with the transfer shaft between the first end portion and the second end portion so as to be rotatable by the air turbine starter.

Providing an air turbine starter that engages the transfer shaft between the ends of the transfer shaft may allow for a gearbox assembly that is more compact, lighter, and/or simpler to construct than a gearbox assembly in which the transfer shaft and the air turbine starter are separately positioned (e.g., on different sides of the gearbox). That is, the integration of the air turbine starter and the transfer shaft may leave room for the air turbine starter to be located. This space may then be occupied by another turbine engine accessory mounted to the gearbox. This may reduce the length of the gear train of the gearbox (and thus the length of the housing of the gearbox), and may thus reduce the size and weight of the gearbox.

This weight and/or size reduction may be caused in part by the removal of the (now unnecessary) idler gear. For example, a gearbox accessory may be configured to operate by receiving torque in a particular direction. In some configurations, the air turbine starter and another engine accessory (e.g., a variable frequency generator) are configured to operate by receiving respective torques having opposite directions (e.g., one clockwise direction, the other counterclockwise direction). If this is the case, and for example the variable frequency generator and the turbine starter are located on the same side of the gear train, an idler gear is required to reverse the direction of torque between them. By moving the air turbine starter to the other side of the gearbox, the air turbine starter and the variable frequency generator may be engaged with the same gear of the gearbox. That is, since they engage either side of the rotating gears (so as to rotate 180 degrees relative to each other), one receives a clockwise torque and the other receives a counterclockwise torque. This means that no idler gear is required to change the direction of the torque applied to the variable frequency generator, which reduces weight and saves space.

The term "operatively connected" is used to describe an arrangement in which movement of the second end portion is transmitted directly or indirectly (i.e., through an intermediate component between the second end portion and the mandrel) to the mandrel of the turbine engine. For example, the second end portion may be engaged with, for example, a radial shaft or a transfer gearbox, which in turn may be connected (directly or indirectly) to the spindle such that rotation of the second end portion causes the spindle to rotate.

Optional features of the present disclosure will now be set forth. These features may be applied alone or in any combination with any of the aspects of the present disclosure.

The axis of rotation of the air turbine starter may be the same as or parallel to the axis of rotation of the transfer shaft. The term "parallel" is used herein to describe a relationship in which the axes of rotation are side-by-side (and have the same distance therebetween in succession).

The transfer shaft may extend through the turbine starter from the first end portion to the second end portion so as to be rotatable by the air turbine starter. The air turbine starter may include an elongated cavity extending therethrough to receive the transfer shaft. In this regard, the transfer shaft may form part of the air turbine starter (or may be a separate component of the air turbine starter).

Alternatively, the transfer shaft may be laterally offset from the air turbine starter. The air turbine starter may operably engage the transfer shaft via the eccentric shaft. The eccentric shaft may extend laterally between the air turbine starter and the transfer shaft. For example, the air turbine starter may include an output shaft, and the eccentric shaft may be engaged with the output shaft so as to be rotatable by the output shaft. This rotation can be transmitted by the eccentric shaft to the transfer shaft.

The transfer shaft may be integral. Alternatively, the transfer shaft may comprise a plurality of elements coupled to each other. For example, the transfer shaft may include a plurality of (e.g., coaxial) shafts coupled to one another (e.g., in an end-to-end arrangement).

The first end portion of the transfer shaft may comprise a spline arrangement for engaging with a corresponding spline arrangement of a gear of the gearbox. The first end portion may alternatively comprise other means for engaging with a gear of the gearbox. For example, the first end portion may comprise spur gears or a coupling/interlocking arrangement for direct engagement with, for example, gears of a gearbox.

The second end portion of the transfer shaft may extend beyond the air turbine starter. The second end portion of the shaft may include radially extending teeth for engaging another component of the turbine engine (e.g., a gear or a radial shaft of a transfer gearbox). The radially extending teeth may be arranged so as to form a bevel gear. The second end portion may have another engagement means (e.g., a spline arrangement).

In some embodiments, the gears of the gearbox may form a gear train. The gear train may extend transversely with respect to the rotational axis of the transfer shaft. The gear may be in the form of a spur gear. The spur gear may be arranged substantially with an axis of rotation substantially parallel to the axis of rotation of the transfer shaft. The gears are each rotatable about a respective integrated axis.

The gearbox may include a housing that encloses (or at least partially encloses) the gear train. The housing may have a first laterally extending side and a second laterally extending side spaced from either side of the gear train. The housing may follow a bend in the transverse direction. The curved portion of the outer shell may generally follow the outer circumferential surface of the turbine engine casing. The gear train of the gearbox may similarly be curved in the lateral direction.

The housing may have a plurality of mounting portions for mounting the engine accessory to the housing. The mounting portion may be located on the first side and the second side of the housing. The mounting portion may include, for example, a locking arrangement, bolt holes, and the like.

The air turbine starter may be mounted to a first side of the housing and another engine accessory may be mounted to a second side of the housing (i.e., engaged with a corresponding gear of the gear train). The other engine accessory may be a variable frequency generator. The variable frequency generator may be positioned substantially aligned with the turbine rotor along the axis of rotation of the shaft. In other words, the variable frequency generator may be positioned directly opposite (or substantially directly opposite) the air turbine starter.

Additional engine accessories may be mounted to the gearbox (and may be engaged with the gear train). These additional engine accessories may include a Permanent Magnet Generator (PMG). The PMG may be positioned on a first side of the gearbox. The PMG may be engaged with a gear of the gear train (i.e., a PMG gear) that is spaced apart from a gear of the gear train (i.e., a transmission shaft gear) with which the transmission shaft is engaged. For example, one or more idler gears may be interposed between the PMG gear and the transfer shaft gear. When the PMG gear and the transfer shaft gear are spaced apart by a single idler gear, the PMG gear and the transfer shaft gear may rotate in the same direction.

A Permanent Magnet Alternator (PMA) may also be mounted to the gearbox (and engaged with the gear train). The PMA may be positioned on a second side of the gearbox. The PMA may engage a gear of the gear train (i.e., a PMA gear) that is spaced apart from a transfer shaft gear of the gear train. For example, one or more idler gears may be interposed between the transfer shaft gear and the PMA gear. A single idler gear may be interposed between the transfer shaft gear and the PMA gear. The PMA may have substantially the same lateral position as the PMG. That is, the PMA may be positioned substantially directly opposite the PMG.

The fuel pump may additionally be mounted to the gearbox (and engaged with the gear train). The fuel pump may be positioned on a first side of the gearbox. The fuel pump may be substantially adjacent to the air turbine starter. Thus, the fuel pump may engage a gear of the gear train (i.e., the fuel pump gear) that is adjacent to (and in meshing engagement with) the transfer shaft gear of the gear train. Thus, the fuel pump gear of the gear train may rotate in the opposite direction to the transfer shaft gear of the gear train.

The hydraulic pump may additionally be mounted to the gearbox (and engaged with the gear train). The hydraulic pump may be positioned on the second side of the gearbox. The hydraulic pump may be laterally spaced from the variable frequency generator. The hydraulic pump may be engaged with a gear that directly engages a fuel pump gear of the gear train (i.e., a hydraulic pump gear). Thus, the hydraulic pump gear may rotate in the opposite direction to the fuel pump gear. The hydraulic pump may be spaced further apart from the air turbine starter in a lateral direction than the fuel pump.

The air turbine starter may include a housing. The housing may include an opening at the first end for allowing the transfer shaft to pass therethrough. The housing may additionally include an opening at the second end for allowing the transfer shaft to pass therethrough. The openings of the housings may be aligned. An elongated cavity may extend through the air turbine starter (i.e., for receiving the transfer shaft) between the openings. The cavity may have a substantially cylindrical shape. The first end of the housing may include a mounting portion for mounting the air turbine starter to the gearbox.

In some embodiments, the air turbine starter may include an air inlet. The air turbine starter may include an air outlet in fluid communication with the air inlet. The air turbine starter may include a turbine rotor in fluid communication with an air inlet and/or an air outlet. The airflow entering the air inlet may thus rotate the turbine rotor.

The air inlet may extend at least partially around the transfer shaft. In this regard, the air inlet may be substantially annular. In other embodiments, the air inlet may be oriented such that the direction of air entering the air inlet is substantially perpendicular to the axis of rotation of the transfer shaft. The air inlet may be arranged such that air entering the inlet is substantially tangential to the turbine rotor. The air inlet may be configured for coupling with an air source (e.g., an external air source) or a conduit for air flow from the air source (e.g., an external air source).

The air turbine starter may include a clutch. The clutch may selectively engage or disengage the air turbine starter from the transfer shaft. Thus, the clutch may be configured between an engaged position and a disengaged position. For example, in the disengaged position, the turbine rotor may be operably disengaged from the transfer shaft. In the engaged position, the turbine rotor may be operably connected to the transfer shaft. The clutch may be brought into the disengaged configuration when the rotational speed of the transmission shaft exceeds the rotational speed of the turbine rotor (or exceeds the rotational speed of the end of the gear arrangement connected to the turbine rotor).

The air turbine starter may also include a gear arrangement (e.g., a gear train) that may be interposed (and connected) between the turbine rotor and the transfer shaft (e.g., between the turbine rotor and the clutch). The gear arrangement may be configured such that the rotational speed of the turbine rotor is different from the rotational speed of the transfer shaft.

In a second aspect, a gas turbine engine is disclosed, comprising: an engine core including a turbine, a compressor, and a spindle connecting the turbine to the compressor; a gearbox assembly as described with respect to the first aspect; and an engine takeoff assembly arranged for transferring rotational motion between the spindle and the gearbox assembly.

The engine takeoff assembly may include a radial shaft extending radially (e.g., substantially radially with respect to an axis of rotation of the spindle) from a spindle of the turbine engine. The radial shaft may be engaged with the second end portion of the transfer shaft. The radial shaft may be engaged with the second end portion of the transfer shaft via one or more gears (e.g., forming part of the transfer gearbox). The transfer shaft may extend substantially parallel to the axis of rotation of the mandrel.

The gas turbine engine may also include a casing surrounding the engine core. The gearbox and engine accessories may be mounted to the housing. The gearbox and engine accessories may be mounted to an outer surface of the core housing. The gearbox and engine accessories may be mounted vertically below the core housing.

The gear train of the gearbox may be arranged so as to extend perpendicular to the rotational axis of the spindle of the engine.

The gas turbine engine may include a fan (with fan blades) positioned upstream of the engine core.

The arrangement of the present disclosure may be particularly, but not exclusively, beneficial for fans driven via a gearbox. Accordingly, the gas turbine engine may include a power gearbox (i.e., in addition to the engine accessory gearbox discussed above) that receives input from the spindle and outputs drive to the fan to drive the fan at a lower rotational speed than the spindle. The input to the power gearbox may come directly from the arbor or indirectly from the arbor, for example via spur gear shafts and/or gears. The spindle may rigidly connect 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 as described and/or claimed herein may have any suitable general architecture. For example, the gas turbine engine may have any desired number of shafts connecting the turbine and the compressor, such as one shaft, two shafts, or three shafts. By way of example only, the turbine connected to the spindle may be a first turbine, the compressor connected to the spindle may be a first compressor, and the spindle may be a first spindle. The engine core may also include a second turbine, a second compressor, and a second spindle connecting the second turbine to the second compressor. The second turbine, the second compressor and the second spindle may be arranged to rotate at a higher rotational speed than the first spindle.

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

The gearbox may be arranged to be driven by a spindle (e.g. the first spindle in the above example) which is configured (e.g. in use) to rotate at the lowest rotational speed. For example, the gearbox may be arranged to be driven only by the spindles (e.g. only the first spindle, not the second spindle in the above example) that are configured to rotate (e.g. in use) at the lowest rotational speed. Alternatively, the gearbox may be arranged to be driven by any one or more shafts, such as the first shaft and/or the second shaft in the above examples.

The gearbox may be a reduction gearbox (since the fan output is at a lower rate of rotation than the input from the spindle). Any type of gearbox may be used. For example, the gearbox may be a "planetary" or "sun" gearbox, as described in more detail elsewhere herein. The gearbox may have any desired reduction ratio (defined as the rotational speed of the input shaft divided by the rotational speed of the output shaft), for example greater than 2.5, for example in the range 3 to 4.2, or 3.2 to 3.8, for example around or at least 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1 or 4.2. For example, the gear ratio may be between any two values in the preceding sentence. By way of example only, the gearbox may be a "sun" gearbox having a gear ratio in the range of 3.1 or 3.2 to 3.8. In some arrangements, the gear ratio may be outside of these ranges.

In any gas turbine engine as described and/or claimed herein, the combustor may be disposed axially downstream of the fan and the one or more compressors. For example, where a second compressor is provided, the combustor may be located directly downstream of (e.g., at the outlet of) the second compressor. By way of another example, where a second turbine is provided, the flow at the combustor outlet may be provided to the inlet of the second turbine. The combustor may be disposed upstream of one or more turbines.

The or each compressor (e.g. the first and second compressors as described above) may comprise any number of stages, for example a plurality of stages. Each stage may include a row of rotor blades and a row of stator vanes, which may be variable stator vanes (as the angle of incidence of the row of stator vanes may be variable). The row of rotor blades and the row of stator vanes may be axially offset from each other.

The or each turbine (e.g. the first and second turbines as described above) may comprise any number of stages, for example a plurality of stages. Each stage may include a row of rotor blades and a row of stator vanes. The row of rotor blades and the row of stator vanes may be axially offset from each other.

Each fan blade may be defined as having a radial span extending from a root (or hub) at a radially inner gas wash position or 0% span position to a tip at a 100% span position. 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 about) any 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 within a range of inclusion defined by any two values in the preceding sentence (i.e., the values may form an upper or lower limit), for example, within a range of 0.28 to 0.32. These ratios may be generally referred to as hub-to-tip ratios. Both the radius at the hub and the radius at the tip may be measured at the leading (or axially forwardmost) portion of the blade. Of course, the hub-to-tip ratio refers to the gas scrubbing portion of the fan blade, i.e., the portion radially outside of any platform.

The radius of the fan may be measured between the engine centerline and the tip at the leading edge of the fan blade. The fan diameter (which may be only twice the fan radius) may be greater than (or about) any one of: 220cm, 230cm, 240cm, 250cm (about 100 inches), 260cm, 270cm (about 105 inches), 280cm (about 110 inches), 290cm (about 115 inches), 300cm (about 120 inches), 310cm, 320cm (about 125 inches), 330cm (about 130 inches), 340cm (about 135 inches), 350cm, 360cm (about 140 inches), 370cm (about 145 inches), 380cm (about 150 inches), 390cm (about 155 inches), 400cm, 410cm (about 160 inches), or 420cm (about 165 inches). The fan diameter may be within an inclusive range defined by any two values in the preceding sentence (i.e., these values may form an upper or lower limit), for example, within a range of 240cm to 280cm or 330cm to 380 cm.

The rotational speed of the fan may vary during use. Generally, for fans having larger diameters, the rotational speed is lower. By way of non-limiting example only, the rotational speed of the fan at cruise conditions may be less than 2500rpm, such as less than 2300 rpm. By way of further non-limiting example only, for an engine with a fan diameter in the range 220cm to 300cm (e.g. 240cm to 280cm or 250cm to 270cm), the rotational speed of the fan at cruise conditions may be in the range 1700rpm to 2500rpm, for example in the range 1800rpm to 2300rpm, for example in the range 1900rpm to 2100 rpm. By way of further non-limiting example only, for an engine with a fan diameter in the range of 330cm to 380cm, the rotational speed of the fan at cruise conditions may be in the range of 1200rpm to 2000rpm, such as in the range of 1300rpm to 1800rpm, such as in the range of 1400rpm to 1800 rpm.

In use of the gas turbine engine, a fan (with associated fan blades) rotates about an axis of rotation. This rotation causes the tips of the fan blades to rotate at a speed U_{Tip end}And (4) moving. The work done by the fan blades 13 on the flow results in an enthalpy rise dH for the flow. Fan tip load may be defined as dH/U_{Tip end} ²Where dH is the enthalpy rise across the fan (e.g., 1-D average enthalpy rise), and U_{Tip end}Is the (translational) speed of the fan tip, e.g. at the leading edge of the tip (which can be defined as the fan tip radius at the leading edge multiplied by the angular speed). The fan tip load at cruise conditions may be greater than (or about) any one of: 0.28, 0.29, 0.3, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39 or 0.4 (all units in this paragraph are Jkg)^-1K^-1/(ms^-1)²). The fan tip load may be any two values from the previous sentenceIncluded within the range defined (i.e., these values may form an upper or lower limit), for example, within the range of 0.28 to 0.31 or 0.29 to 0.3.

A gas turbine engine according to the present disclosure may have any desired bypass ratio, where the 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 cruise conditions. In some arrangements, the bypass ratio may be greater than (or about) any one of: 10. 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5 or 20. The bypass ratio may be within an inclusive range defined by any two values in the preceding sentence (i.e., the values may form an upper or lower limit), for example, within a range of 13 to 16, or a range of 13 to 15, or a range of 13 to 14. The bypass conduit may be substantially annular. The bypass duct may be located radially outward of the engine core. The radially outer surface of the bypass duct may be defined by the nacelle and/or the fan casing.

The overall pressure ratio of the gas turbine engine described and/or claimed herein may be defined as the ratio of the stagnation pressure upstream of the fan to the stagnation pressure at the highest pressure compressor outlet (before entering the combustor). By way of non-limiting example, the overall pressure ratio at cruise of a gas turbine engine as described and/or claimed herein may be greater than (or about) any one of: 35. 40, 45, 50, 55, 60, 65, 70, 75. The overall pressure ratio may be within an inclusive range defined by any two values in the preceding sentence (i.e., the values may form an upper or lower limit), for example, within a range of 50 to 70.

The specific thrust of the engine may be defined as the net thrust of the engine divided by the total mass flow through the engine. At cruise conditions, the specific thrust of the engines described and/or claimed herein may be less than (or about) any of the following: 110Nkg^-1s、105Nkg^-1s、100Nkg^-1s、95Nkg^-1s、90Nkg^-1s、85Nkg^-1s or 80Nkg^-1And s. The specific thrust may be defined by any two values in the preceding sentence (i.e., these values may form an upper or lower limit)) In the range of (1), e.g. 80NKg^-1s to 100NKg^-1s, or 85NKg^-1s to 95NKg^-1s is in the range of. Such engines may be particularly efficient compared to conventional gas turbine engines.

A gas turbine engine as described and/or claimed herein may have any desired maximum thrust. By way of non-limiting example only, a gas turbine as described and/or claimed herein is capable of producing a maximum thrust of at least (or about) any one of: 160kN, 170kN, 180kN, 190kN, 200kN, 250kN, 300kN, 350kN, 400kN, 450kN, 500kN or 550 kN. The maximum thrust may be within the inclusive range defined by any two values in the preceding sentence (i.e., these values may form an upper or lower limit). By way of example only, a gas turbine as described and/or claimed herein may be capable of producing a maximum thrust in a range of 330kN to 420kN, for example 350kN to 400 kN. The thrust referred to above may be the maximum net thrust at standard atmospheric conditions, at sea level, plus 15 ℃ (ambient pressure 101.3kPa, temperature 30 ℃), with the engine at rest.

In use, the temperature of the flow at the inlet of the high pressure turbine may be particularly high. This temperature, which may be referred to as TET, may be measured at the outlet of the combustor, for example immediately upstream of a first turbine vane, which may be referred to as a nozzle guide vane. At cruise, the TET may be at least (or about) any of the following: 1400K, 1450K, 1500K, 1550K, 1600K or 1650K. The TET at cruise may be within an inclusive range defined by any two values in the preceding sentence (i.e., the values may form an upper or lower limit). The maximum TET used by the engine may be, for example, at least (or about) any of: 1700K, 1750K, 1800K, 1850K, 1900K, 1950K or 2000K. The maximum TET may be within an inclusive range defined by any two values in the preceding sentence (i.e., the values may form an upper or lower limit), for example, within a range of 1800K to 1950K. The maximum TET may occur, for example, under high thrust conditions, such as Maximum Takeoff (MTO) conditions.

The fan blades and/or airfoil portions of fan blades described and/or claimed herein may be fabricated from any suitable material or combination of materials. For example, at least a portion of the fan blade and/or airfoil may be at least partially fabricated from a composite material, such as a metal matrix composite material and/or an organic matrix composite material, such as carbon fiber. By way of further example, at least a portion of the fan blade and/or airfoil may be fabricated at least partially from a metal, such as 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 regions fabricated using different materials. For example, a fan blade may have a protective leading edge that may be manufactured using a material that is better resistant to impacts (e.g., from birds, ice, or other materials) than the rest of the blade. Such a leading edge may be manufactured, for example, using titanium or a titanium-based alloy. Thus, by way of example only, the fan blade may have a carbon fiber or have an aluminum-based body with a titanium leading edge (such as an aluminum lithium alloy).

A fan as described and/or claimed herein may include a central portion from which fan blades may extend, for example, in a radial direction. The fan blades may be attached to the central portion in any desired manner. For example, each fan blade may include a fastener that may engage a corresponding slot in the hub (or disk). By way of example only, such fasteners may be of dovetail form that may be inserted into and/or engage corresponding slots in the hub/disk to secure the fan blade to the hub/disk. By way of further example, the fan blade may be integrally formed with the central portion. Such an arrangement may be referred to as a blisk or a blisk ring. Any suitable method may be used to manufacture such a blisk or blisk. For example, at least a portion of the fan blade may be machined from a block and/or at least a portion of the fan blade may be attached to the hub/disk by welding (such as linear friction welding).

The gas turbine engines described and/or claimed herein may or may not be provided with Variable Area Nozzles (VANs). Such variable area nozzles may allow the outlet area of the bypass duct to vary in use. The general principles of the present disclosure may be applied to engines with or without a VAN.

The fan of a gas turbine as described and/or claimed herein may have any desired number of fan blades, such as 14, 16, 18, 20, 22, 24, or 26 fan blades.

As used herein, cruise conditions may refer to cruise conditions of an aircraft to which the gas turbine engine is attached. Such cruise conditions may generally be defined as conditions at mid-cruise, such as conditions experienced by the aircraft and/or engine at the midpoint (in terms of time and/or distance) between the climb apex and the descent start point.

By way of example only, the forward speed at cruise conditions may be at any point in the range from mach 0.7 to mach 0.9, such as 0.75 to 0.85, such as 0.76 to 0.84, such as 0.77 to 0.83, such as 0.78 to 0.82, such as 0.79 to 0.81, such as about mach 0.8, about mach 0.85, or 0.8 to 0.85. Any single speed within these ranges may be a cruise condition. For some aircraft, cruise conditions may be outside of these ranges, such as below mach 0.7 or above mach 0.9.

By way of example only, the cruise conditions may correspond to standard atmospheric conditions at an altitude within the following ranges: 10000m to 15000m, for example in the range 10000m to 12000m, for example in the range 10400m to 11600m (about 38000 feet), for example in the range 10500m to 11500m, for example in the range 10600m to 11400m, for example in the range 10700m (about 35000 feet) to 11300m, for example in the range 10800m to 11200m, for example in the range 10900m to 11100m, for example about 11000 m. Cruise conditions may correspond to standard atmospheric conditions at any given altitude within these ranges.

By way of example only, the cruise conditions may correspond to: forward mach number 0.8; a pressure of 23000 Pa; and a temperature of-55 ℃. Also by way of example only, the cruise conditions may correspond to: forward mach number 0.85; pressure 24000 Pa; and a temperature of-54 ℃ (which may be standard atmospheric conditions at 35000 feet).

As used anywhere herein, "cruise" or "cruise conditions" may refer to aerodynamic design points. Such aerodynamic design points (or ADPs) may correspond to conditions under which the fan is designed to operate (including, for example, one or more of mach number, ambient conditions, and thrust requirements). For example, this may refer to the condition where the fan (or gas turbine engine) is designed to have optimal efficiency.

In use, the gas turbine engine described and/or claimed herein may be operated at cruise conditions as defined elsewhere herein. Such cruise conditions may be determined by the cruise conditions (e.g., mid-cruise conditions) of an aircraft on which at least one (e.g., 2 or 4) gas turbine engines may be mounted to provide propulsive thrust.

In a third aspect, an air turbine starter for a gas turbine engine is provided. The air turbine starter includes an air inlet; a drive assembly extending through the air turbine starter between a first end configured for operable connection with a gearbox of the turbine engine and a second end portion for operable connection with a spindle of the turbine engine; and a turbine rotor in fluid communication with the air inlet and operatively connected to the drive assembly to rotate the drive assembly.

The transmission assembly may include a shaft that extends (completely or partially) through the air turbine starter. The transmission assembly may include a plurality of shafts coupled to one another. The shafts may be coaxial. The shafts may be coupled in an end-to-end arrangement. For example, the shafts may be engaged with each other by a spline connection. One or more shafts may extend completely through the air turbine starter so as to extend beyond the end of the turbine starter.

The turbine rotor may be connected to a drive assembly (e.g., a shaft or shafts) by a splined connection. The air turbine starter may include a clutch, and the turbine rotor may engage the transmission assembly via the clutch. The clutch may selectively engage and disengage the turbine rotor from the drive assembly.

The air inlet may be annular. The air inlet may at least partially surround the first end portion or the second end portion.

The air turbine starter may be as described above with respect to the first aspect. The transmission assembly (and the first and second end portions) may be in the form of a transmission shaft as described with respect to the first aspect. For example, the first end portion and/or the second end portion may include radially extending teeth, a spline arrangement, or the like.

Those skilled in the art will appreciate that features or parameters described in relation to any one of the above aspects are applicable to any other aspect unless mutually exclusive. Further, unless mutually exclusive, any feature or parameter described herein may be applied to any aspect and/or in combination with any other feature or parameter described herein.

Drawings

Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional side view of a gas turbine engine;

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

FIG. 3 is a partial cross-sectional view of a gearbox for a gas turbine engine;

FIG. 4 is a schematic view of a gearbox assembly;

FIG. 5A is a schematic illustration of an air turbine starter arrangement; and

FIG. 5B is a schematic view of a variation of the air turbine starter arrangement of FIG. 5A.

Detailed Description

Aspects and embodiments of the present disclosure will now be discussed with reference to the drawings. Additional aspects and embodiments will be apparent to those skilled in the art.

Fig. 1 shows a gas turbine engine 10 having a main axis of rotation 9. The engine 10 comprises an air intake 12 and a propeller fan 23 which generates two air flows: core stream a and bypass stream B. The gas turbine engine 10 includes a core 11 that receives a core gas flow A. The engine core 11 includes, in axial flow series, a low pressure compressor 14, a high pressure compressor 15, a combustion apparatus 16, a high pressure turbine 17, a low pressure turbine 19, and a core exhaust nozzle 20. Nacelle 21 surrounds gas turbine engine 10 and defines bypass duct 22 and 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 gearbox 30.

In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 for further compression. The compressed air discharged from the high-pressure compressor 15 is led into a combustion device 16, where the compressed air is mixed with fuel and the mixture is combusted. The resulting hot combustion products are then expanded by the high and low pressure turbines 17, 19 before being discharged through the nozzle 20, thereby driving the high and low pressure turbines 17, 19 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by means of a suitable interconnecting shaft 27. The fan 23 typically provides the majority of the propulsive thrust. The epicyclic gearbox 30 is a reduction gearbox.

An exemplary arrangement of the geared fan gas turbine engine 10 is shown in FIG. 2. The low pressure turbine 19 (see fig. 1) drives a shaft 26, which shaft 26 is coupled to a sun gear or sun gear 28 of an epicyclic gear arrangement 30. Radially outward of and intermeshed with the sun gear 28 is a plurality of planet gears 32 that are coupled together by a carrier 34. The planet carrier 34 constrains the planet gears 32 to precess synchronously about the sun gear 28, while rotating each planet gear 32 about its own axis. The planet carrier 34 is coupled to the fan 23 via a connecting rod 36 for driving the fan in rotation about the engine axis 9. Radially outward of and intermeshes with the planet gears 32 is a ring gear or ring gear 38 that is coupled to the fixed support structure 24 via a linkage 40.

It is noted that the terms "low pressure turbine" and "low pressure compressor" as used herein may refer to the lowest pressure turbine stage and lowest pressure compressor stage, respectively (i.e., not including the fan 23), and/or the turbine and compressor stages that are connected together by an interconnecting shaft 26 having the lowest rotational speed in the engine (i.e., not including the gearbox output shaft that drives the fan 23). In some documents, the "low pressure turbine" and "low pressure compressor" referred to herein may alternatively be referred to as an "intermediate pressure turbine" and an "intermediate pressure compressor". Where such alternative nomenclature is used, the fan 23 may be referred to as the first or lowest pressure compression stage.

The epicyclic gearbox 30 is shown in more detail in figure 3 by way of example. Each of the sun gear 28, planet gears 32, and ring gear 38 includes teeth around its periphery for intermeshing with other gears. However, for clarity, only exemplary portions of the teeth are shown in FIG. 3. Four planet gears 32 are shown, but it will be apparent to those skilled in the art that more or fewer planet gears 32 may be provided within the scope of the claimed invention. Practical applications of planetary epicyclic gearbox 30 typically include at least three planet gears 32.

The epicyclic gearbox 30 shown by way of example in fig. 2 and 3 is planetary, with a planet carrier 34 coupled to the output shaft via a connecting rod 36, with a ring gear 38 fixed. However, any other suitable type of epicyclic gearbox 30 may be used. By way of another example, the epicyclic gearbox 30 may be a sun arrangement in which the planet carrier 34 is held stationary, allowing the ring gear (or ring gear) 38 to rotate. In such an arrangement, the fan 23 is driven by the ring gear 38. By way of another alternative example, the gearbox 30 may be a differential gearbox in which both the ring gear 38 and the planet carrier 34 are allowed to rotate.

It should be understood that the arrangements shown in fig. 2 and 3 are exemplary only, and that various alternatives are within the scope of the present disclosure. By way of example only, any suitable arrangement may be used to position the power gearbox 30 in the engine 10 and/or to connect the power gearbox 30 to the engine 10. By way of another example, the connections (such as the links 36, 40 in the example of FIG. 2) between the power gearbox 30 and other components of the engine 10 (such as the input shaft 26, the output shaft, and the fixed structure 24) may have any desired degree of stiffness or flexibility. By way of another example, any suitable arrangement of bearings between rotating and stationary components of the engine (e.g., between input and output shafts from a gearbox and a stationary structure such as a gearbox housing) may be used, and the present disclosure is not limited to the exemplary arrangement of fig. 2. For example, where the power gearbox 30 has a sun arrangement (as described above), the skilled person will readily appreciate that the arrangement of the output and support links and bearing locations will generally differ from that shown by way of example in figure 2.

Accordingly, the present disclosure extends to gas turbine engines having any of a gearbox type (e.g., sun or planetary gear), support structure, input and output shaft arrangements, and bearing locations.

Optionally, the gearbox may drive additional and/or alternative components (e.g., a medium pressure compressor and/or a booster compressor).

Other gas turbine engines to which the present disclosure is applicable may have alternative configurations. For example, such engines may have an alternative number of compressors and/or turbines and/or an alternative number of interconnecting shafts. By way of further example, the gas turbine engine shown in FIG. 1 has split nozzles 18, 20, which means that the flow through the bypass duct 22 has its own nozzle 18 that is separate from and radially outside of the core exhaust nozzle 20. However, this is not limiting and any aspect of the present disclosure may also be applied to engines in which the flow through the bypass duct 22 and the flow through the core 11 are mixed or combined before (or upstream of) a single nozzle, which may be referred to as a mixed flow nozzle. One or both nozzles (whether mixed or split) may have a fixed or variable area. Although the described examples relate to turbofan engines, the present disclosure is applicable to any type of gas turbine engine, such as an open rotor (where the fan stages are not surrounded by a nacelle) or, for example, a turboprop engine. In some arrangements, the gas turbine engine 10 may not include the gearbox 30.

The geometry of the gas turbine engine 10 and its components are defined by conventional shafting, including axial (aligned with the axis of rotation 9), radial (in the direction from bottom to top in fig. 1), and circumferential (perpendicular to the page in the view of fig. 1). The axial, radial and circumferential directions are mutually perpendicular.

FIG. 4 illustrates a gearbox assembly for a gas turbine engine such as that shown in FIGS. 1-3. The gearbox assembly 39 includes an accessory gearbox 40 having a plurality of spur gears 41a, 41b, 41c, 41d, 41e, 41f arranged in a gear train 42 that extends in a generally linear manner within a housing 43 of the gearbox 40. In this regard, the gearbox housing 43 has a first side 44 and a second side 45 extending on either side of the gear train 42. A plurality of engine accessories, one of which is an air turbine starter 46, are engaged with the gear train 42 of the gearbox 40.

The air turbine starter 46 is shown in more detail in FIG. 5A. The air turbine starter 46 includes a housing 47 defining an air inlet 48 and an air outlet 49, and a turbine rotor 50 in fluid communication with the air inlet 48 and the air outlet 49. As can be clearly seen from the schematic view, in operation, air (e.g., pressurized air) flows into the air inlet 48 (e.g., supplied by an external air source) and across the blades of the turbine rotor 50 to rotate the turbine rotor 50 about the turbine axis 51. Although not explicitly seen in the schematic view, the air inlet 48 and the air outlet 49 may each include, for example, a mesh grid that prevents unwanted objects (i.e., objects that may cause damage to the turbine rotor 50) from entering the air turbine starter 46.

A transfer shaft 55 is shown extending through the air turbine starter 46. The transfer shaft 55 is connected to the turbine rotor 50 via the gear arrangement 53 and the clutch 54. The gear arrangement 53 operatively connects the turbine rotor 50 to the clutch 54. In particular, the gear arrangement 53 is configured as a reduction gear train such that the end of the gear arrangement 53 that engages the clutch 54 rotates at a lower speed than the end of the gear arrangement 53 that engages the turbine rotor 50. In other words, the gear arrangement 53 is configured to increase torque.

The clutch 54 may be configured between an engaged position and a disengaged position. In the disengaged position, the turbine rotor 50 is operatively disengaged from the transfer shaft 55 by the clutch 54. In this way, rotation of the turbine rotor 50 has no effect on the transfer shaft 55 (and vice versa). In the engaged position, the clutch 54 operatively connects the turbine rotor 50 to the transfer shaft 55. Thus, when engaged, the clutch 54 transfers the rotational motion of the turbine rotor 50 to the transfer shaft 55. In particular, the clutch 54 is configured to move from the engaged position to the disengaged position when the rotational speed of the transfer shaft 55 exceeds the rotational speed of the end of the gear arrangement 53 that is engaged with the clutch 54.

As will be explained further below, this may occur when the air turbine starter 46 is connected to the engine core of the turbine engine via the transfer shaft 55 (and other transmission components of the turbine engine) and is used to provide initial rotation of the spindle of the engine core. During the start-up phase, the end of the gear arrangement 53 connected to the clutch 54 may rotate at a faster speed than the transfer shaft 55 (caused by the rotation of the turbine rotor 50). However, once the engine core is fully started such that it rotates under its own power, the transfer shaft 55 may rotate at a faster speed than the end of the gear arrangement 53 that engages the clutch 52 (i.e. caused by the engine core rotating the transfer shaft 55). When this occurs, the clutch 54 disengages the gear arrangement 54 (and thus the turbine rotor 50) from the transfer shaft 55.

The transfer shaft 55 extends through the air turbine starter 46 such that opposing first and second end portions 56, 57 of the transfer shaft 55 protrude out of the housing 47. As will be understood from the figures, the clutch 54 is engaged with the transfer shaft 55 at a position between these first and second end portions 56, 57.

The first end portion 56 of the shaft 55 includes a spline arrangement 58. This spline arrangement 58 allows the first end portion 56 of the shaft 55 to engage with the gear train 42 of the gearbox 40 (i.e., via a splined connection with the gears of the gearbox). To further facilitate this engagement, the housing 47 of the air turbine starter 46 includes a mounting portion 60 for mounting the air turbine starter 46 to the housing 43 of the gear box 40. These mounting portions may be in the form of holes, for example, for mounting the housing 43 by a bolt and nut arrangement.

The second end portion 57 of the transfer shaft 55 comprises a plurality of radially protruding teeth arranged to form a bevel gear 59. The bevel gear 59 allows the second end portion 57 of the transfer shaft 55 to engage with a further shaft 61 (i.e. with a corresponding bevel gear). The further shaft 61 may for example be a radial shaft of a turbine engine for transmitting rotational motion between the engine core and the air turbine starter 46.

Fig. 5B shows a variation of the arrangement of fig. 5A. Since the arrangement is similar to that shown in fig. 5A, similar numbering is used. In fig. 5B, the transfer shaft 55 'does not pass through the air turbine starter 46'. In contrast, the transfer shaft 55 'is laterally offset from the air turbine starter 46' (i.e., the rotational axes of the air turbine starter 46 'and the transfer shaft 55' are laterally offset, but remain parallel). Thus, the air turbine starter 46 'engages the transfer shaft 55' via the eccentric shaft 62 that extends laterally between the transfer shaft 55 '(between the first and second end portions 56, 57 of the transfer shaft) and the output shaft 62 of the air turbine starter 46'. The eccentric shaft 62 may engage the output shaft 62 and the transfer shaft 55' by, for example, a meshing engagement, gearing arrangement, spline connection, or the like.

Returning now to fig. 4, the turbine air starter 46 is mounted to the first side 44 of the housing 43 of the gearbox 40 (i.e., through the mounting portion 60), and the first end portion 56 of the transfer shaft 55 is engaged with the gear train 42 of the gearbox 40. In the illustrated embodiment (although not shown), the first end portion 56 of the transfer shaft 55 is coupled to the gear 41c of the gear train 42, but in other embodiments the first end portion 56 of the transfer shaft 55 may form part of the gear train 42 (i.e., the first end portion 56 may be a gear in the gear train 42).

A transfer shaft 55 operatively connects the engine core to the gearbox 40, and the air turbine starter 46 provides initial movement to the engine core by engaging the transfer shaft 55 between a first end portion 56 and a second end portion 57. In known configurations, the turbine starter would instead be mounted to the gearbox at another location. For example, it is known to position the turbine starter directly opposite the transfer shaft (i.e., on the opposite side of the gearbox). In the presently described embodiment, because the turbine starter 46 is integrated with the transfer shaft 55, a space is created where the air turbine starter 46 would otherwise be located.

In this embodiment, the space is filled by a variable frequency generator 62. The variable frequency generator 62 is positioned on the second side 45 of the gearbox 40 and is generally aligned with the rotational axis 51 of the transfer shaft 55. The variable frequency generator 62 and the transmission shaft 55 are coupled to (or engage) the same gear 41c of the gear train 42.

In addition to the air turbine starter 46 and the variable frequency generator 62, the plurality of engine accessories of the gearbox assembly 39 include a hydraulic pump 63, a fuel pump 64, a Permanent Magnet Generator (PMG)65, and a Permanent Magnet Alternator (PMA) 66. Each of these engine accessories is powered by torque supplied by the engine core, which is provided via the gear train 42 and transfer shaft 55 of the gearbox 40.

The fuel pump 64 is positioned on the same side of the gearbox housing 43 (i.e., the first side 44) as the air turbine starter 46. Specifically, the fuel pump 64 is adjacent to the air turbine starter 46 and engages with the gear 41d of the gear train 42, and the gear 41d is adjacent to the gear 41c with which the air turbine starter 46 engages (via the transmission shaft 55). Accordingly, a rotating member (e.g., an impeller) of the fuel pump 64 rotates in a direction opposite to the shaft 55 of the air turbine starter 46.

The PMG 65 is also positioned on the first side 44 of the gearbox 40 and on the opposite side of the air turbine starter 46 from the fuel pump 64. The PMG 65 is engaged with the gear 41a, and the gear 41a is spaced from the gear 41c with which the air turbine starter 46 is engaged by the idler gear 41 b. Thus, the rotor of the PMG 65 rotates in the same direction as the shaft 55 of the air turbine starter 46. The PMA 66 is mounted to the gearbox 40 directly opposite the PMG 65, on the second side 45 of the gearbox 40, and engages the same gear 41a of the gear train 42 as the PMG 65.

The hydraulic pump 63 is also mounted on the second side 45 of the gearbox 40 (on the opposite side of the frequency conversion unit 62 from the PMA 66). The hydraulic pump 63 is engaged with the gear 41f of the gear train 42, and the gear 41f is adjacent to the gear 41e with which the fuel pump 64 is engaged. Therefore, the gear 41f with which the hydraulic pump 63 is engaged rotates in a direction different from the gear 41e with which the fuel pump 64 is engaged.

It is to be understood that the present invention is not limited to the above-described embodiments, and various modifications and improvements may be made without departing from the concept described herein. Any feature may be used alone or in combination with any other feature or features unless mutually exclusive, and the disclosure extends to and includes all combinations and subcombinations of one or more features described herein.