Epicyclic gear train
View Patent ↗A turbine engine has a fan shaft. At least one tapered bearing is mounted on the fan shaft. The fan shaft includes at least one passage extending in a direction having at least a radial component, and adjacent the at least one tapered bearing. A fan is mounted for rotation on the tapered bearing. An epicyclic gear train is coupled to drive the fan. The epicyclic gear train includes a carrier supporting intermediate gears that mesh with a sun gear. A ring gear surrounds and meshes with the intermediate gears. Each of the intermediate gears are supported on a respective journal bearing. The epicyclic gear train defines a gear reduction ratio of greater than or equal to about 2.3. A turbine section is coupled to drive the fan through the epicyclic gear train. The turbine section has a fan drive turbine that includes a pressure ratio that is greater than about 5. The fan includes a pressure ratio that is less than about 1.45, and the fan has a bypass ratio of greater than about ten (10).
1. A turbine engine comprising:
a fan shaft;
at least one tapered bearing mounted on the fan shaft, the fan shaft including at least one passage extending in a direction having at least a radial component, and adjacent the at least one tapered bearing;
a fan mounted for rotation on the tapered bearing;
an epicyclic gear train coupled to drive the fan, the epicyclic gear train including a carrier supporting intermediate gears that mesh with a sun gear, and a ring gear surrounding and meshing with the intermediate gears, each of the intermediate gears being supported on a respective journal bearing, wherein the epicyclic gear train defines a gear reduction ratio of greater than or equal to about 2.3; and
a turbine section coupled to drive the fan through the epicyclic gear train, the turbine section having a fan drive turbine that includes a pressure ratio that is greater than about 5, the fan includes a pressure ratio that is less than about 1.45, and the fan has a bypass ratio of greater than about ten (10).
2. The turbine engine as recited in claim 1 , wherein the fan shaft is coupled to the ring gear.
3. The turbine engine as recited in claim 1 , wherein the at least one tapered bearing includes a first tapered bearing and the at least one passage includes a first passage and a second passage, the first passage being located at an axially forward side of the first tapered bearing and the second passage being located at an axially aft side of the first tapered bearing.
4. The turbine engine as recited in claim 1 , wherein the fan shaft includes, on a radially inner surface, at least one well extending between axial sides and a radial side, and the at least one passage opens at the radial side.
5. The turbine engine as recited in claim 1 , wherein the fan shaft includes, on a radially inner surface, a plurality of wells each extending between axial side walls and a radial side wall, and the at least one passage includes a plurality of passages that open at respective ones of the radial side walls of the plurality of wells.
6. The turbine engine as recited in claim 5 , wherein two wells of the plurality of wells are axially adjacent such that the two wells share a common axial side wall.
7. The turbine engine as recited in claim 5 , wherein the axial side walls are gradually sloped.
8. The turbine engine as recited in claim 1 , wherein the epicyclic gear train has a gear reduction ratio of greater than or equal to 2.3.
9. The turbine engine as recited in claim 1 , wherein the epicyclic gear train has a gear reduction ratio of greater than or equal to about 2.5.
10. The turbine engine as recited in claim 1 , wherein the epicyclic gear train has a gear reduction ratio of greater than or equal to 2.5.
11. The turbine engine as recited in claim 1 , wherein the fan defines a bypass ratio of greater than about 10.5:1 with regard to a bypass airflow and a core airflow.
12. The turbine engine as recited in claim 1 , wherein there are three turbines, with said fan drive turbine being a lowest pressure turbine, and there being a high pressure turbine and an intermediate pressure turbine, with said high pressure turbine and said intermediate pressure turbine each driving a compressor rotor.