Epicyclic geartrain

Abstract

An epicyclic geartrain comprises a sun gear, a plurality of planet gears, and a ring gear. The plurality of planet gears is supported by a planet torque ring. The planet gears meshingly surround the sun gear, and the ring gear meshingly surrounds the planet gears. At least one of the sun gear, the plurality of planet gears, and the ring gear, is provided with a plurality of permanent magnet portions. Each of the plurality of magnet portions is arranged as a circumferential array. The planet torque ring is provided with at least one stator coil array, with the or each stator coil array being positioned in axial alignment with the or each corresponding plurality of permanent magnet portions as an axial flux electric motor generator element.

Claims

1. An epicyclic geartrain comprising: a sun gear; a plurality of planet gears supported by a planet torque ring; and a ring gear, wherein: the planet gears meshingly surround the sun gear; the ring gear meshingly surrounds the planet gears; at least the sun gear is provided with a plurality of permanent magnet portions arranged as a circumferential array; and the planet torque ring is provided with at least one stator coil array, the or each stator coil array being positioned in axial alignment with the or each corresponding plurality of permanent magnet portions as an axial flux electric motor generator element.

2. The epicyclic geartrain as claimed in claim 1, wherein each of the plurality of planet gears is provided with a plurality of permanent magnet portions arranged as a circumferential array.

3. The epicyclic geartrain as claimed in claim 1, wherein each of the plurality of planet gears and the ring gear are provided with a plurality of permanent magnet portions arranged as a circumferential array.

4. The epicyclic geartrain as claimed in claim 1, wherein the plurality of magnet portions is arranged as a spaced circumferential array.

5. The epicyclic geartrain as claimed in claim 1, wherein each one of the plurality of magnet portions is attached to an axial face of a corresponding one of the sun gear, plurality of planet gears, and ring gear.

6. The epicyclic geartrain as claimed in claim 1, wherein each stator coil array comprises C individual coil portions, each circumferential array of magnet portions comprises M individual magnet portions, and a ratio of C/M is in the range of 0.2 to 1.0.

7. The epicyclic geartrain as claimed in claim 1, wherein: the sun gear comprises eight permanent magnet portions; and a stator coil array on a corresponding region of the planet torque ring comprises six coil portions.

8. The epicyclic geartrain as claimed in claim 1, wherein each planet gear comprises eight permanent magnet portions; and for each planet gear, a stator coil array on a corresponding region of the planet torque ring comprises six coil portions.

9. The epicyclic geartrain as claimed in claim 1, wherein the ring gear comprises one hundred permanent magnet portions; and a stator coil array on a corresponding region of the planet torque ring comprises thirty-two coil portions.

10. An epicyclic geartrain comprising: a sun gear; a plurality of planet gears supported by a planet torque ring; and a ring gear, wherein: the planet gears meshingly surround the sun gear; the ring gear meshingly surrounds the planet gears; at least one of the sun gear, the plurality of planet gears, and the ring gear is provided with a plurality of permanent magnet portions arranged as a circumferential array; the planet torque ring is provided with at least one stator coil array, the or each stator coil array being positioned in axial alignment with the or each corresponding plurality of permanent magnet portions as an axial flux electric motor generator element; and each stator coil array comprises at least six coil portions, the six coil portions being arranged as a circumferential array.

11. A geared turbofan engine comprising: a fan; a core gas turbine engine; and a gearbox, wherein the gearbox connects the fan to the core gas turbine engine, and the gearbox comprises an epicyclic geartrain comprising: a sun gear; a plurality of planet gears supported by a planet torque ring; and a ring gear, wherein: the planet gears meshingly surround the sun gear; the ring gear meshingly surrounds the planet gears; at least one of the sun gear, the plurality of planet gears, and the ring gear is provided with a plurality of permanent magnet portions arranged as a circumferential array; and the planet torque ring is provided with at least one stator coil array, the or each stator coil array being positioned in axial alignment with the or each corresponding plurality of permanent magnet portions as an axial flux electric motor generator element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There now follows a description of an embodiment of the disclosure, by way of non-limiting example, with reference being made to the accompanying drawings in which:

(2) FIG. 1 shows a schematic sectional view of a geared turbofan gas turbine engine incorporating an epicyclic geartrain according to the present disclosure;

(3) FIG. 2 shows an enlarged schematic view of the gearbox region of the engine of FIG. 1;

(4) FIG. 3 shows a schematic axial view of the gearbox of the engine of FIG. 1;

(5) FIG. 4 shows schematic cross-sectional and axial views of the epicyclic geartrain of the present disclosure, illustrating the magnet portion placement; and

(6) FIG. 5 shows schematic cross-sectional and axial views of the epicyclic geartrain of the present disclosure, illustrating the stator coil portion placement.

(7) It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawings, like numbering represents like elements between the drawings.

DETAILED DESCRIPTION

(8) A typical arrangement of the epicyclic gearbox 30 used in a geared turbofan gas turbine engine 10 is shown in FIG. 3. Each of the sun gear 28, planet gears 32 and ring gear 38 comprise teeth about their periphery to intermesh with the other gears. However, for clarity only exemplary portions of the teeth are illustrated in FIG. 3. There are four planet gears 32 illustrated, although it will be apparent to the skilled reader that more or fewer planet gears 32 may be provided within the scope of the claimed invention. Practical applications of a planetary epicyclic gearbox 30 generally comprise at least three planet gears 32.

(9) Referring to FIG. 3, an epicyclic geartrain according to an embodiment of the disclosure is designated generally by the reference numeral 100.

(10) As illustrated in FIG. 4, the epicyclic geartrain 100 comprises a sun gear 110, a plurality of planet gears 120, and a ring gear 130. Each of the plurality of planet gears 120 is rotationally attached to a planet torque ring 122. Each of the planet gears 120 is free to rotate relative to the planet torque ring 122.

(11) In the present embodiment, the epicyclic geartrain 100 is configured in a planetary configuration, in which the sun gear 110 rotates in a first direction, and the planet torque ring 122 (together with the plurality of planet gears 120) rotates in a second opposite direction, while the ring gear 130 remains stationary. The epicyclic geartrain 100 of the present disclosure may however equally be applied to epicyclic gearbox configurations of the star or differential form.

(12) The planet torque ring 122 is positioned in an axial plane. The planet torque ring 122 is axially offset from the ring gear 130 by an axial clearance 124.

(13) In the present embodiment the epicyclic geartrain 100 comprises five planet gears 120. As outlined above, other embodiments of the disclosure may comprise an alternative quantity, say four or six for example, of planet gears 120.

(14) Each of the planet gears 120 meshes with the sun gear 120, and the planet gears are positioned to surround the sun gear 110. The ring gear 130 meshes with each of the planet gears 120, and the ring gear 130 is positioned to surround the planet gears 120.

(15) The sun gear 110 and the ring gear 130 are positioned to be coaxial. The planet gears 120 are arranged in a circumferential array around the sun gear 110.

(16) Each of the sun gear 110, the planet gears 120, and the ring gear 130 is provided with a plurality of permanent magnet portions 140. For each of the sun gear 110, the planet gears 120, and the ring gear 130, the plurality of permanent magnet portions 140 are arranged as a circumferential array 142. In other words, each of the sun gear 110, the planet gears 120, and the ring gear 130, itself comprises a circumferential array of permanent magnet portions 140.

(17) In the present embodiment, the sun gear 110 comprises eight (8) permanent magnet portions 140, and the corresponding region of the planet torque ring 122 comprises six (6) stator coil arrays 150. Likewise, each planet gear 120 comprises eight (8) permanent magnet portions 140, and the corresponding region of the planet torque ring 122 comprises six (6) stator coil arrays 150. In contrast, the ring gear 130 provides one hundred (100) permanent magnet portions 140, and the corresponding region of the planet torque ring 122 comprises thirty-two (32) stator coil arrays 150.

(18) In the present embodiment, each circumferential array 142 of permanent magnet portions 140 is integrally formed with a respective one of the sun gear 110, the planet gears 120, and the ring gear 130. In other words, the circumferential array 142 of permanent magnet portions 140 is embedded in the body of the respective sun gear 110, planet gear 120, and ring gear 130.

(19) As illustrated in FIG. 5, the planet torque ring 122 comprises a number of stator coil arrays 150. Each stator coil array 150 corresponds to a respective one of the arrays 142 of permanent magnets 140. There is a stator coil array 150 for each one of the sun gear 110, the planet gears 120, and the ring gear 130.

(20) Each corresponding pair of stator coil array 150 and array 142 of permanent magnet portions 140 together forms an axial flux electric motor generator element 160. The axial clearance 124 between each ones of the corresponding pair of stator coil array 150 and array 142 of permanent magnet portions 140 may be varied to alter the electrical performance of the respective axial flux electric motor generator element 160.

(21) In use, a rotary input 102 to the epicyclic geartrain 100 drives the sun gear 110. The sun gear 110 has a rotational motion 116. The sun gear 100 then drives each of the planet gears 120 with rotational motion 126. In the present arrangement, the ring gear 130 remains stationary.

(22) Various example embodiments of the invention are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the invention. Various changes may be made to the invention described and equivalents may be substituted without departing from the scope of the invention. Further, it will be appreciated by those with skill in the art that each of the individual variations described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope of the present inventions. All such modifications are intended to be within the scope of claims associated with this disclosure.

(23) In addition, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention.

(24) Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

(25) The foregoing description of various aspects of the disclosure has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed, and obviously, many modifications and variations are possible. Such modifications and variations that may be apparent to a person of skill in the art are included within the scope of the disclosure as defined by the accompanying claims.