Epicyclic gearbox
An epicyclic gear train includes planetary gears rotatably mounted on spindles supported by an annular carrier and including axially spaced apart forward and aft sets of output teeth extending radially outwardly from a planetary gear hub and axially spaced apart forward and aft roller bearings disposed between planetary gears and spindles. The forward and aft roller bearings are axially aligned with or adjacent to spaced apart forward set of output teeth and input gear respectively. A ring gear meshes with forward set of output teeth and an external gear meshes with aft set of output teeth. An input gear fixedly attached to hub aft of aft set of output teeth and engaged with a sun gear. The output teeth, input gear, ring gear, external gear, and sun gear may all be helical. A turbofan gas turbine engine may include counter-rotatable first and second fan stages driven by a low pressure turbine through the gear train.
1. An epicyclic gear train comprising:
planetary gears rotatably mounted on spindles supported by an annular carrier,
each of the planetary gears including a hollow planetary gear hub and axially spaced apart forward and aft sets of output teeth extending radially outwardly from the planetary gear hub,
axially spaced apart forward and aft roller bearings disposed between the planetary gears and the spindles,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears,
and
the forward roller bearing being axially aligned with the forward set of output teeth and the aft roller bearing being axially adjacent to the input gear.
2. An epicyclic gear train as claimed in claim 1 , further comprising a ring gear circumscribing and meshing with the forward set of output teeth and an external gear meshing with the aft set of output teeth.
3. An epicyclic gear train as claimed in claim 2 , further comprising the input gear of each of the planetary gears meshing with a sun gear.
4. An epicyclic gear train as claimed in claim 2 , further comprising the forward set of output teeth meshing with the ring gear radially outwardly of the spindles and the aft set of output teeth meshing with the external gear radially inwardly of the spindles.
5. An epicyclic gear train as claimed in claim 4 , further comprising the input gear of each of the planetary gears meshing with a sun gear radially inwardly of the spindles.
6. An epicyclic gear train as claimed in claim 5 , further comprising the forward and aft set of output teeth, the input gear of the planetary gears, the ring gear, the external gear, and the sun gear being helical.
7. An epicyclic gear train comprising:
planetary gears rotatably mounted on spindles supported by an annular carrier,
each of the planetary gears including a hollow planetary gear hub and axially spaced apart forward and aft sets of output teeth extending radially outwardly from the planetary gear hub,
axially spaced apart forward and aft roller bearings disposed between the planetary gears and the spindles,
a ring gear circumscribing and meshing with the forward set of output teeth and an external gear meshing with the aft set of output teeth,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears,
the forward set of output teeth meshing with the ring gear radially outwardly of the spindles and the aft set of output teeth meshing with the external gear radially inwardly of the spindles,
the input gear of each of the planetary gears meshing with a sun gear radially inwardly of the spindles,
the forward roller bearing being axially aligned with the forward set of output teeth and the aft roller bearing being axially adjacent to the input gear.
8. An epicyclic gear train as claimed in claim 7 , further comprising the forward and aft set of output teeth, the input gear of the planetary gears, the ring gear, the external gear, and the sun gear being helical.
9. An epicyclic gearbox comprising:
an epicyclic gear train including planetary gears rotatably mounted on spindles supported by forward and aft conical carrier frames of an annular carrier,
the forward and aft conical carrier frames including radially outer forward and aft carrier flanges respectively,
the forward and aft conical carrier frames including radially inner forward and aft support flanges respectively fixedly supporting the spindles therebetween,
the forward and aft support flanges connected by conical forward and aft support beams to the forward and aft carrier flanges,
each of the planetary gears including a hollow planetary gear hub and axially spaced apart forward and aft sets of output teeth extending radially outwardly from the planetary gear hub,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears,
the input gear of each of the planetary gears meshing with a sun gear, and
axially spaced apart forward and aft roller bearings disposed between the planetary gears and the spindles.
10. An epicyclic gearbox as claimed in claim 9 , further comprising the forward and aft roller bearing being axially aligned with or adjacent to the spaced apart forward set of output teeth and the input gear respectively.
11. An epicyclic gearbox as claimed in claim 10 , further comprising the forward roller bearing being axially aligned with the forward set of output teeth and the aft roller bearing being axially adjacent to the input gear.
12. An epicyclic gearbox as claimed in claim 10 , further comprising:
the forward set of output teeth meshing with the ring gear radially outwardly of the spindles,
the aft set of output teeth meshing with the external gear radially inwardly of the spindles, and
the input gear of each of the planetary gears meshing with the sun gear radially inwardly of the spindles.
13. An epicyclic gearbox as claimed in claim 12 , further comprising the forward and aft set of output teeth, the input gear of the planetary gears, the ring gear, the external gear, and the sun gear being helical.
14. A turbofan gas turbine engine comprising:
a fan section including counter-rotatable first and second fan stages radially supported, at least in part, by a fan frame,
a low pressure turbine downstream of the fan section and drivingly connected to the first and second fan stages by a low pressure shaft through an epicyclic gear train in an epicyclic gearbox,
the epicyclic gear train including planetary gears rotatably mounted on spindles supported by an annular carrier,
each of the planetary gears including a hollow planetary gear hub and axially spaced apart forward and aft sets of output teeth extending radially outwardly from the planetary gear hub,
axially spaced apart forward and aft roller bearings disposed between the planetary gears and the spindles,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears,
and
the forward roller bearing being axially aligned with the forward set of output teeth and the aft roller bearing being axially adjacent to the input gear.
15. A turbofan gas turbine engine comprising:
a fan section including counter-rotatable first and second fan stages radially supported, at least in part, by a fan frame,
a low pressure turbine downstream of the fan section and drivingly connected to the first and second fan stages by a low pressure shaft through an epicyclic gear train in an epicyclic gearbox,
the epicyclic gear train including planetary gears rotatably mounted on spindles supported by an annular carrier,
each of the planetary gears including a hollow planetary gear hub and axially spaced apart forward and aft sets of output teeth extending radially outwardly from the planetary gear hub,
axially spaced apart forward and aft roller bearings disposed between the planetary gears and the spindles,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears,
the second fan stage connected to a ring gear circumscribing and meshing with the forward set of output teeth,
the first fan stage connected to an external gear meshing with the aft set of output teeth,
an input gear fixedly attached to the planetary gear hub aft of the aft set of output teeth of each of the planetary gears, and
the input gear of each of the planetary gears meshing with a sun gear connected to the low pressure shaft.
16. A turbofan gas turbine engine as claimed in claim 15 , further comprising:
the forward set of output teeth meshing with the ring gear radially outwardly of the spindles,
the aft set of output teeth meshing with the external gear radially inwardly of the spindles, and
the input gear of each of the planetary gears meshing with the sun gear radially inwardly of the spindles.
17. A turbofan gas turbine engine as claimed in claim 16 , further comprising the forward and aft roller bearing being axially aligned with or adjacent to the spaced apart forward set of output teeth and the input gear respectively.
18. A turbofan gas turbine engine as claimed in claim 17 , further comprising the forward and aft set of output teeth, the input gear of the planetary gears, the ring gear, the external gear, and the sun gear being helical.
19. A turbofan gas turbine engine as claimed in claim 17 , further comprising the forward roller bearing being axially aligned with the forward set of output teeth and the aft roller bearing being axially adjacent to the input gear.
20. A turbofan gas turbine engine as claimed in claim 19 , further comprising the forward and aft set of output teeth, the input gear of the planetary gears, the ring gear, the external gear, and the sun gear being helical.
21. A turbofan gas turbine engine as claimed in claim 17 , further comprising the spindles supported by forward and aft conical carrier frames of the annular carrier,
the forward and aft conical carrier frames including radially outer forward and aft carrier flanges respectively and mounted to and supported by the fan frame,
the forward and aft conical carrier frames including radially inner forward and aft support flanges respectively fixedly supporting the spindles therebetween, and
the forward and aft support flanges connected by conical forward and aft support beams to the forward and aft carrier flanges.