Gas turbine engine dual towershaft accessory gearbox assembly with a transmission

Patent metadata

Field	Value
Publication number	US-10590852-B2
Application number	US-201715409889-A
Country	US
Kind code	B2
Filing date	Jan 19, 2017
Priority date	Jan 19, 2017
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A gas turbine engine assembly includes a turbine section having first and second turbines mounted for rotation about a common rotational axis within an engine static structure, first and second turbine shafts coaxial with one another and to which the first and second turbines are respectively operatively mounted, first and second towershafts respectively coupled to the first and second turbine shafts, an accessory drive gearbox mounted to the engine static structure, and a transmission transitionable between a first mode where an electric machine is driven at a first speed relative to the first towershaft, and a second mode where the electric machine is driven at a different, second speed relative to the first towershaft.

First claim

What is claimed is:

1. A method of driving accessories through an accessory drive gearbox of a gas turbine engine, comprising:
rotating a first turbine shaft to drive a first towershaft, and rotating a second turbine shaft to drive a second towershaft, the first and second turbine shafts mounted for rotation about a common rotational axis within an engine static structure;
driving a first set of gears of the accessory drive gearbox with the first towershaft, and driving a second set of gears of the accessory drive gearbox with the second towershaft;
driving a transmission with the first set of gears to rotate an electric machine at a first speed relative to the first towershaft when the transmission is in a first mode;
transitioning the transmission to a second mode;
driving the transmission with the first set of gears to rotate the electric machine at a different, second speed relative to the first towershaft in the second mode;
housing the first and second sets of gears within a common housing of the accessory drive gearbox;
driving an oil pump with the first set of gears at a third speed relative to the first towershaft when the transmission is in the first mode, and driving the oil pump with the first set of gears at the third speed relative to the first towershaft when the transmission is in the second mode, and wherein the oil pump is driven at a fixed ratio relative to the speed of the first towershaft in both the first and second modes;
communicating a supply of oil to a bearing system with the oil pump, the oil pump being dedicated to communicating oil to the bearing system, the bearing system including a bearing supporting the first turbine shaft at a position axially forward of the accessory drive gearbox relative to the common rotation axis;
wherein the engine static structure includes an intermediate case surrounding a core flow path defined along a compressor section driven by a turbine section, the accessory drive gearbox is mounted to the intermediate case, the intermediate case includes a first strut and a second strut directly circumferentially adjacent to the first strut with respect to the common rotational axis, the first towershaft extends through the first strut, and the second towershaft extends through the second strut; and
wherein the first and second turbine shafts are inner and outer shafts, respectively, the turbine section includes a first turbine and a second turbine, and the first and second turbines are low and high pressure turbines, respectively.

2. The method of claim 1 , wherein the first turbine shaft is configured to drive a fan through a geared architecture such that the fan rotates at a lower speed than the first turbine shaft.

3. The method of claim 1 , further comprising driving at least one of a hydraulic pump, a fuel pump, or a permanent magnet alternator with the second set of gears.

4. The method of claim 1 , wherein the second towershaft is configured to rotate at a higher speed than the first towershaft.

5. The method of claim 2 , wherein the step of supplying oil to the bearing system with the oil pump occurs during a windmilling event.

6. The method of claim 3 , further comprising coupling an air turbine starter to the second towershaft via the second set of gears.

7. A gas turbine engine assembly comprising:
a turbine section having a first turbine and a second turbine, the first and second turbines mounted for rotation about a common rotational axis within an engine static structure;
a first turbine shaft arranged coaxially with a second turbine shaft, wherein the first turbine is operatively mounted to the first turbine shaft, and the second turbine is operatively mounted to the second turbine shaft;
a first towershaft coupled to the first turbine shaft and a second towershaft coupled to the second turbine shaft;
an accessory drive gearbox mounted to the engine static structure, the accessory drive gearbox including a common housing, a first set of gears and a second set of gears arranged within the common housing, the first towershaft extending into the common housing and coupled to the first set of gears, the second towershaft extending into the common housing and coupled to the second set of gears;
an electric machine; and
a transmission coupling the electric machine to the first set of gears, the transmission transitionable between a first mode where the electric machine is driven at a first speed relative to the first towershaft in operation, and a second mode where the electric machine is driven at a different, second speed relative to the first towershaft in operation; and
wherein the engine static structure includes an intermediate case surrounding a core flow path defined along a compressor section driven by the turbine section, the accessory drive gearbox is mounted to the intermediate case, the intermediate case includes a first strut and a second strut directly circumferentially adjacent to the first strut with respect to the common rotational axis, the first towershaft extends through the first strut, and the second towershaft extends through the second strut;
wherein the first and second turbine shafts are inner and outer shafts, respectively, and the first and second turbines are low and high pressure turbines, respectively;
wherein a first set of accessories are configured to be rotationally driven by the first towershaft through the first set of gears, the first set of accessories including the electric machine and an oil pump; and
wherein the oil pump is dedicated to communicate oil to a bearing system including a bearing supporting the first turbine shaft at a position axially forward of the accessory drive gearbox relative to the common rotational axis, and the oil pump is driven at a fixed ration relative to a speed of the first towershaft in both the first second modes.

8. The gas turbine engine assembly of claim 7 , wherein the second towershaft is configured to rotate at a higher speed than the first towershaft.

9. The gas turbine engine assembly of claim 7 , wherein a second set of accessories are configured to be rotationally driven by the second towershaft through the second set of gears.

10. The gas turbine engine assembly of claim 9 , wherein:
the second towershaft is configured to rotate at a higher speed than the first towershaft; and
the first set of gears is not in meshing engagement with the second set of gears.

11. The gas turbine engine assembly of claim 10 , further comprising:
an air turbine starter coupled to the second towershaft via the second set of gears;
wherein the second set of accessories includes a hydraulic pump, a fuel pump, and a permanent magnet alternator; and
wherein the electric machine is an integrated drive generator.

12. The gas turbine engine assembly of claim 10 , wherein:
the first turbine shaft drives a fan through a geared architecture such that the fan rotates at a lower speed than the first turbine shaft; and
the oil pump is configured to communicate oil to the bearing system in response to rotation of the fan during a windmilling event.

13. The gas turbine engine assembly of claim 12 , wherein the bearing is a thrust bearing.

14. The gas turbine engine assembly of claim 9 , wherein the electric machine is driven at a third speed relative to the oil pump when the transmission is in the first mode, and the electric machine is driven at a different, fourth speed relative to the oil pump when the transmission is in the second mode.

15. The gas turbine engine assembly of claim 9 , wherein the second set of accessories includes at least one of a hydraulic pump, a fuel pump, or

Assignees

• United Technologies Corp

Inventors

• Suciu Gabriel L
• Duong Hung
• Zimmitti Jonathan F
• Sheridan William G
• Mccune Michael E
• Merry Brian

Classifications

• F02C7/06 Primary

  Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M) · CPC title

• F02C7/32 Primary

  Arrangement, mounting, or driving, of auxiliaries · CPC title

• F05D2220/76

  an electrical generator · CPC title

• F05D2260/4031

  as in toothed gearing · CPC title

• F05D2240/50

  Bearings · CPC title