Dual clutch transmission for accessory gearbox drive

1. A power extraction system for a gas turbine engine, comprising:

a low spool transmission including a low tower shaft and a low lay shaft rotationally coupled to the low tower shaft; and

a low spool accessory gearbox comprising a generator and a dual clutch transmission coupled between the low spool transmission and the generator, wherein the dual clutch transmission includes:

a first clutch;

a first transmission shaft operationally coupled to the first clutch;

a second clutch;

a second transmission shaft operationally coupled to the second clutch;

a plurality of gears including at least a first gear coupled to the first transmission shaft and a second gear coupled to the second transmission; and

a countershaft including a plurality of counter gears, the counter gears being configured to engage the plurality of gears, wherein gear ratios for all of the gears of the plurality of gears relative to the counter gears of the plurality of counter gears are configured to increase a rotational speed of the countershaft relative to a rotational speed of the low lay shaft.

2. The power extraction system of claim 1 , wherein the plurality of gears further comprises:

a third gear mounted to the first transmission shaft; and

a fourth gear mounted to the second transmission shaft.

3. The power extraction system of claim 1 , wherein an output gear of the countershaft is configured to drive a rotation of an input shaft of the generator.

4. The power extraction system of claim 1 , wherein

the low lay shaft forms an input shaft of the dual clutch transmission.

5. The power extraction system of claim 4 , further comprising:

a high spool transmission; and

a high accessory gearbox including a first accessory operationally coupled to the high spool transmission.

6. The power extraction system of claim 5 , wherein the high spool transmission comprises:

a high tower shaft; and

a high lay shaft rotationally coupled to the high tower shaft, and wherein the high accessory gearbox comprises a gear train, the gear train including an input gear rotationally coupled to high lay shaft.

7. A gas turbine engine, comprising:

a high spool and a low spool;

a high spool transmission mechanically coupled to the high spool;

a low spool transmission mechanically coupled to the low spool; and

a low accessory gearbox comprising a generator and a dual clutch transmission coupled between the low spool transmission and the generator, the dual clutch transmission including:

a first clutch;

a first transmission shaft operationally coupled to the first clutch;

a second clutch;

a second transmission shaft operationally coupled to the second clutch;

a plurality of gears including at least a first gear coupled to the first transmission shaft and a second gear coupled to the second transmission; and

a countershaft including a plurality of counter gears, the counter gears being configured to engage the plurality of gears, wherein gear ratios for all of the gears of the plurality of gears relative to the counter gears of the plurality of counter gears are configured to increase a rotational speed of the countershaft relative to a rotational speed of the low lay shaft.

8. The gas turbine engine of claim 7 , further comprising:

a controller operationally coupled to the first clutch and the second clutch; and

a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising:

determining, by the controller, a rotational speed of at least one of the low spool transmission or the low spool; and

determining, by the controller, a desired gear ratio of the dual clutch transmission based on the rotational speed of the at least one of the low spool transmission or the low spool.

9. The gas turbine engine of claim 8 , wherein the operations further comprise:

determining, by the controller, if the desired gear ratio of the dual clutch transmission matches a current gear ratio of the dual clutch transmission;

commanding, by the controller, the first clutch to engage if the desired gear ratio of the dual clutch transmission does not match the current gear ratio of the dual clutch transmission; and

commanding, by the controller, the second clutch to disengage if the desired gear ratio of the dual clutch transmission does not match the current gear ratio of the dual clutch transmission.

10. The gas turbine engine of claim 7 , wherein an output gear of the countershaft is configured to drive a rotation of an input shaft of the generator.

11. The gas turbine engine of claim 10 , wherein the plurality of gears further comprises:

a third gear mounted to the first transmission shaft; and

a fourth gear mounted to the second transmission shaft.

12. The gas turbine engine of claim 7 , wherein the low spool transmission comprises:

a low tower shaft rotationally coupled to the low spool; and

a low lay shaft rotationally coupled to the low tower shaft, wherein the low lay shaft forms an input shaft of the dual clutch transmission.

13. The gas turbine engine of claim 12 , wherein the high spool transmission comprises:

a high tower shaft rotationally coupled to the high spool;

a high lay shaft rotationally coupled to the high tower shaft; and

a high spool accessory gearbox including a first accessory and a gear train operationally coupled to the first accessory, the gear train including an input gear rotationally coupled to the high lay shaft.

14. A method of forming a power extraction system for a gas turbine engine, comprising:

coupling a low spool transmission to a low spool of the gas turbine engine, wherein the low spool transmission includes a low tower shaft rotationally coupled to the low spool and a low lay shaft rotationally coupled to the low tower shaft;

coupling a dual clutch transmission to the low spool transmission, wherein the low lay shaft forms an input shaft of the dual clutch transmission, and wherein the dual clutch transmission comprises:

a first clutch;

a first transmission shaft operationally coupled to the first clutch;

a second clutch;

a second transmission shaft operationally coupled to the second clutch;

a plurality of gears including at least a first gear coupled to the first transmission shaft and a second gear coupled to the second transmission; and

a countershaft including a plurality of counter gears configured to engage the plurality of gears, wherein gear ratios for all of the gears of the plurality of gears relative to the counter gears of the plurality of counter gears are configured to increase a rotational speed of the countershaft relative to a rotational speed of the low lay shaft; and

rotationally coupling an output gear of the countershaft to an input gear of an accessory of a low accessory gearbox.

15. The method of claim 14 , further comprising operationally coupling a controller to the dual clutch transmission, the controller including a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising:

determining, by the controller, a rotational speed of at least one of the low spool transmission or the low spool; and

determining, by the controller, a desired gear ratio of the dual clutch transmission based on the rotational speed of the at least one of the low spool transmission or the low spool.

16. The method of claim 15 , wherein the operations further comprise:

determining, by the controller, if the desired gear ratio of the dual clutch transmission matches a current gear ratio of the dual clutch transmission;

commanding, by the controller, the first clutch to engage if the desired gear ratio of the dual clutch transmission does not match the current gear ratio of the dual clutch transmission; and

commanding, by the controller, the second clutch to disengage if the desired gear ratio of the dual clutch transmission does not match the current gear ratio of the dual clutch transmission.

17. The method of claim 16 , wherein the determining, by the controller, the rotational speed of the at least one of the low spool transmission or the low spool comprises:

receiving, by the controller, a signal from a sensor configured to measure an operating condition of the gas turbine engine.

18. The method of claim 17 , wherein the accessory of the low accessory gearbox comprises a generator.