Geared gas turbine engine and a gearbox
A gas turbine engine comprises a gearbox comprises a sun gear, an annulus gear, a plurality of planet gears and a carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. The planet gear carrier comprising a first ring, a second ring spaced axially from the first ring and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring. Each planet gear is rotatably mounted on a respective one of the axles and the axles are arranged at a first radius. At least one of the first ring and the second ring comprises a metal matrix composite material ring and the metal matrix composite ring comprises a ring of reinforcing fibres and the ring of reinforcing fibres having a second radius greater than the first radius.
1. A gas turbine engine comprising a gearbox,
the gearbox comprising: a sun gear; an annulus gear; a plurality of planet gears; and a carrier,
the sun gear meshing with the planet gears and the planet gears meshing with the annulus gear;
the carrier comprising a first ring, a second ring spaced axially from the first ring, and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring;
each planet gear being rotatably mounted on a respective one of the plurality of circumferentially spaced axles;
each of the plurality of circumferentially spaced axles being arranged at a first radius;
at least one of the first ring and the second ring comprising a metal matrix composite material;
the metal matrix composite material comprising a ring of reinforcing fibres; and
the ring of reinforcing fibres having a second radius greater than the first radius.
2. A gas turbine engine as claimed in claim 1 , wherein
the first ring comprises a first metal matrix composite material and the second ring comprises a second metal matrix composite material;
the first metal matrix composite material comprises a first ring of reinforcing fibres, the first ring of reinforcing fibres having a second radius greater than the first radius; and
the second metal matrix composite material comprises a second ring of reinforcing fibres, the second ring of reinforcing fibres having a second radius greater than the first radius.
3. A gas turbine engine as claimed in claim 2 , wherein the first ring and the second ring are secured together.
4. A gas turbine engine as claimed in claim 2 , wherein the first metal matrix composite material comprises a metal matrix selected from a group consisting essentially of a steel matrix, a titanium matrix, and a titanium alloy matrix.
5. A gas turbine engine as claimed in claim 2 , wherein the first metal matrix composite material comprises reinforcing fibres selected from a group consisting essentially of silicon carbide fibres, silicon nitride fibres, and boron nitride fibres.
6. A gas turbine engine as claimed in claim 2 , wherein the second metal matrix composite material comprises a metal matrix selected from a group consisting essentially of a steel matrix, a titanium matrix, and a titanium alloy matrix.
7. A gas turbine engine as claimed in claim 2 , wherein the second metal matrix composite material comprises reinforcing fibres selected from a group consisting essentially of silicon carbide fibres, silicon nitride fibres, and boron nitride fibres.
8. A gas turbine engine as claimed in claim 1 , wherein each of the plurality of circumferentially spaced axles comprises a third metal matrix composite material, the third metal matrix composite material comprising reinforcing fibres extending axially between the first ring and the second ring.
9. A gas turbine engine as claimed in claim 8 , wherein the third metal matrix composite material comprises a metal matrix selected from a group consisting essentially of a steel matrix, a titanium matrix, and a titanium alloy matrix.
10. A gas turbine engine as claimed in claim 8 , wherein the third metal matrix composite material comprises silicon carbide fibres, silicon nitride fibres, or boron nitride fibres.
11. A gas turbine engine as claimed in claim 1 , wherein each planet gear is rotatably mounted on the carrier by a bearing selected from a group consisting essentially of a journal bearing and at least one rolling element bearing.
12. A gas turbine engine as claimed in claim 11 , wherein each planet gear is rotatably mounted on the carrier by two rolling element bearings.
13. A gas turbine engine as claimed in claim 1 , wherein the carrier is connected to an output shaft and the annulus gear is connected to a static structure.
14. A gas turbine engine as claimed in claim 1 , wherein the carrier is connected to a static structure and the annulus gear is connected to an output shaft.
15. A gas turbine engine as claimed in claim 1 , wherein
the gas turbine engine comprises a propulsor, an intermediate-pressure compressor, a high-pressure compressor, a high-pressure turbine, and a low-pressure turbine;
the high-pressure turbine is arranged to directly drive the high-pressure compressor
the low-pressure turbine is arranged to directly drive the intermediate-pressure compressor; and
the low-pressure turbine is arranged to drive the propulsor via the gearbox.
16. A gas turbine engine as claimed in claim 15 , wherein the propulsor is selected from a group consisting essentially of a fan and a propeller.
17. A gas turbine engine as claimed in claim 1 , wherein
the gas turbine engine comprises a low-pressure turbine, a static structure, and a propulsor;
the sun gear is driven by the low-pressure turbine;
the annulus gear is secured to the static structure; and
the carrier is arranged to drive the propulsor.
18. A gas turbine engine as claimed in claim 1 , wherein
the gas turbine engine comprises a low-pressure turbine, a static structure, and a propulsor;
the sun gear is driven by the low-pressure turbine;
the carrier is secured to the static structure; and
the annulus gear is arranged to drive the propulsor.
19. A gearbox comprising:
a sun gear; an annulus gear; a plurality of planet gears; and a carrier,
the sun gear meshing with the planet gears and the planet gears meshing with the annulus gear;
the carrier comprising a first ring, a second ring spaced axially from the first ring, and a plurality of circumferentially spaced axles extending axially between the first ring and the second ring;
each planet gear being rotatably mounted on a respective one of the plurality of circumferentially spaced axles, each of the plurality of circumferentially spaced axles being arranged at a first radius; and
at least one of the first ring and the second ring comprising a metal matrix composite material, the metal matrix composite material comprising a ring of reinforcing fibres, and the ring of reinforcing fibres having a second radius greater than the first radius.
20. A planet gear carrier comprising:
a first ring;
a second ring spaced axially from the first ring;
a plurality of circumferentially spaced axles extending axially between the first ring and the second ring; and
a plurality of planet gears,
each planet gear being rotatably mounted on a respective one of the plurality of circumferentially spaced axles, each of the plurality of circumferentially spaced axles being arranged at a first radius; and
at least one of the first ring and the second ring comprising a metal matrix composite material, the metal matrix composite material comprising a ring of reinforcing fibres, and the ring of reinforcing fibres having a second radius greater than the first radius.