Gear train for gas geared gas turbine engine
A gas turbine engine including a fan and an oil pump operatively connected to the fan by a main input drive gear, the drive gear rotating when the fan rotor rotates in either a first or second direction of the fan. Further included is a gear train intermediate the main input drive gear and the oil pump, the gear train including a first and second pinion gear, the first and second pinion gear each driven by the main input drive gear, the first pinion gear driving a first gear through a first clutch, the second pinion gear driving a second gear through a second clutch. Only one of the clutches transmits rotation from the respective pinion gear to the respective gear when the fan is rotating in the first direction, with the only the other clutch transmitting rotation when the fan is rotating in the second direction.
1. A gas turbine engine comprising:
a fan driven by a fan drive turbine through a gear reduction;
an oil pump operatively connected to the fan by a main input drive gear, the main input drive gear rotating when the fan rotates in either a first direction or a second direction of the fan; and
a gear train intermediate the main input drive gear and the oil pump, the gear train including a first pinion gear and a second pinion gear, the first pinion gear and the second pinion gear each in contact with and directly driven by the main input drive gear, the first pinion gear driving a first gear through a first clutch; the second pinion gear driving a second gear through a second clutch, the first gear and the second gear in contact with each other;
wherein the first clutch transmits rotation from the first pinion gear to the first gear when the fan is rotating in the first direction, the first clutch not transmitting rotation from the first pinion gear to the first gear when the fan is rotating in the second direction;
wherein the second clutch does not transmit rotation from the second pinion gear to the second gear when the fan is rotating in the first direction, the second clutch transmitting rotation from the second pinion gear to the second gear when the fan is rotating in the second direction.
2. The gas turbine engine of claim 1 , wherein the oil pump is rotatable about a common axis with the first pinion gear.
3. The gas turbine engine of claim 1 , wherein the oil pump is rotatable about a common axis with the second pinion gear.
4. The gas turbine engine of claim 1 , wherein said first and second clutches are sprag clutches.
5. The gas turbine engine of claim 1 , wherein the gear train is operable to allow the engine to operate under windmill conditions in the aft for 90 minutes or longer.
6. The gas turbine engine of claim 1 , wherein the gas turbine engine is operable to fly under negative gravity conditions for at least 20 seconds.
7. The gas turbine engine of claim 1 , wherein the gear train is operable indefinitely on the ground when windmilling with wind speeds below 85 mph or less.
8. An oil pump gear train assembly of a gas turbine engine having a fan driven by a fan drive turbine through a gear reduction, the assembly comprising:
an oil pump operatively connected to the fan by a main input drive gear, the main input drive gear rotating when the fan rotates in either a first direction or a second direction of the fan; and
a gear train intermediate the main input drive gear and the oil pump, the gear train comprising:
a first pinion gear in contact with, and directly driven by, the main input drive gear;
a second pinion gear in contact with, and directly driven by, the main input drive gear;
a first gear driven by the first pinion gear through a first clutch; and
a second gear driven by the second pinion gear through a second clutch,
the first gear and the second gear in contact with each other;
wherein the first clutch transmits rotation from the first pinion gear to the first gear when the fan is rotating in the first direction, the first clutch not transmitting rotation from the first pinion gear to the first gear when the fan is rotating in the second direction;
wherein the second clutch does not transmit rotation from the second pinion gear to the second gear when the fan is rotating in the first direction, the second clutch transmitting rotation from the second pinion gear to the second gear when the fan is rotating in the second direction.
9. The oil pump gear train of claim 8 , wherein the oil pump is rotatable about a common axis with the first pinion gear.
10. The oil pump gear train of claim 8 ; wherein the oil pump is rotatable about a common axis with the second pinion gear.
11. The oil pump gear train of claim 8 , wherein said first and second clutches are sprag clutches.
12. The oil pump gear train of claim 8 , wherein the gear train is operable to avow the engine to operate under windmill conditions in the air for 90 minutes or longer.
13. The oil pump gear train of claim 8 , wherein the gas turbine engine is operable to fly under negative gravity conditions for at least 20 seconds.
14. The oil pump gear train of claim 8 , wherein the gear train is operable indefinitely on the ground when windmilling with wind speeds below 85 mph or less.