Engine with start assist

Patent metadata

Field	Value
Publication number	US-11466623-B2
Application number	US-202117314576-A
Country	US
Kind code	B2
Filing date	May 7, 2021
Priority date	Sep 27, 2018
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

An engine comprises a first power input and a second power input, a main load, and a transmission engaged with the first power input, the second power input, and the main load. An epicyclic gear train is engaged with the first power input and the main load. A brake in a drive condition engages with the epicyclic gear train to transfer power from the first power input to the main load. The brake in a start condition disengages from the epicyclic gear train to decouple the first power input from the main load. A start assist motor is engaged with part of the transmission separate from the epicyclic gear train. The start assist motor in the start condition rotates the main load to initiate start up of the engine, and in the drive condition prevents transferring power to the main load.

First claim

The invention claimed is:

1. A method of operating an engine at a start condition in which the engine is starting up and at a drive condition in which the engine is in full operation, the engine having a first power input and a second power input, the method comprising:
in the start condition in which the engine is starting up,
allowing free rotation of gears of an epicyclic gear train of a transmission to limit or prevent power transfer from the first pow r input to a main load of the engine; and
driving part of the transmission separate from the epicyclic gear train with the second power input to transfer power from the second power input to the main load and initiate rotation of the main load; and

In the drive condition in which the engine is in full operation,
braking one of the gears of the epicyclic gear train to transfer power from the first power input to the main load; and
preventing the second power input from transferring power to the main by rotationally locking the second power input.

2. The method of claim 1 , wherein allowing free rotation of gears of the epicyclic gear train includes driving the second power input with the notating gears of the epicyclic gear train.

3. The method of claim 1 , wherein allowing free notation of gears of the epicyclic gear train includes rotating the gears about a first axis, and wherein driving part of the transmission separate from the epicyclic gear train with the second power input includes rotating the second power input about a second axis that is spaced apart from the first axis.

4. The method of claim 1 , wherein driving part of the transmission separate from the epicyclic gear train with the second paw input includes driving part of the transmission with the second power input for an initial period after braking one of the gears of the epicyclic gear train.

5. The method of claim 1 , wherein preventing the second power input from transferring power to the main load includes preventing the second power input from transferring power to the main load while simultaneously braking one of the gears of the epicyclic gear train.

6. The method of claim 1 , wherein allowing free rotation of gears of the epicyclic gear train includes generating electrical energy with the notating gears and storing the electrical energy in a battery.

7. The method of claim 6 , wherein driving part of the transmission separate from the epicyclic gear train with the second paw input includes driving part of the transmission with the second power input using the electrical energy from the battery.

8. The method of claim 1 , wherein preventing the second power input from transferring power to the main load includes inactivating the second power input.

9. A method of operating an engine at a start condition in which the engine is starting up and at a drive condition in which the engine is in full operation, the engine having a first power input and a second power input, the method comprising:
in the start condition in which the engine is starting up,
allowing free rotation of wars of an epicyclic gear train of a transmission to limit or prevent power transfer from the first power input to a main load of the engine; and
driving cart of the transmission separate from the epicyclic gear train with the second power input to transfer power from the second power input to the main bad and initiate rotation of the main load, to transfer power from the second paw input to accessories of an accessory gearbox and initiate rotation of the accessories; and

in the drive condition in which the engine is in full operation,
braking one of the gears of the epicyclic gear train to transfer power from the first power input to the main load; and
preventing the second power input from transferring power to the main load.

10. The method of claim 9 , wherein driving part of the transmission separate from the epicyclic gear train with the second power input includes driving part of the transmission with the second power input for an initial period after braking one of the gears of the epicyclic gear train.

11. A method of operating an engine at a start condition in which the engine is starting up and at a drive condition in which the engine is in full operation, the engine having a first power input and a second power input, the method comprising:
in the start condition in which the engine is starting up,
rotationally locking the main load and allowing free rotation of gears of an epicyclic gear train of a transmission to limit or prevent power transfer from the first power input to a main load of the engine, and
driving part of the transmission separate from the epicyclic gear train with the second power input to transfer power from the second power input to the main load and initiate rotation of the main load; and

in the drive condition in which the engine is in full operation,
braking one of the gears of the epicyclic gear train to transfer power from the first power input to the main load; and
preventing the second power input from transferring power to the main load.

12. An engine, comprising:
a first power input and a second power input;
a main load;
a transmission engaged with and between the first power input, the second power input and the main load, the transmission comprising:
an epicyclic gear train engaged with the first power input and selectively engageable with the main load; and
a brake engagable in a drive condition with the epicyclic gear train to transfer power from the first power input to the main load, the brake in a start condition disengageable from the epicyclic gear train to decouple the first power input from the main load;

a start assist motor associated with the second power input and engaged with part of the transmission separate from the epicyclic gear train, the start assist motor in the start condition rotating the main load to initiate start up of the engine, the start assist motor and a secondary load being rotationally locked in the drive condition, the start assist motor in the drive condition thereby being prevented from transferring power to the main load.

13. The engine of claim 12 , comprising the secondary load to be driven by the first power load.

14. The engine of claim 13 , wherein the secondary load is one of the gears of the epicyclic gear train, the first pow input in the start condition driving said gear, the gear thereby freely rotating.

15. The engine of claim 14 , wherein said gear freely notating generates electrical energy, the engine comprising a battery to store the electrical energy, and to provide the electrical energy to drive the start assist motor.

16. The engine of claim 13 , wherein the secondary load is one of the gears of the epicyclic gear train, the first power input driving said gear of the epicyclic gear train, said gear of the epicyclic gear train driving the start assist motor.

17. The engine of claim 13 , wherein the brake disengages from one of the gears of the epicyclic gear train to decouple the first pow input from the main load, and subsequently engages said gear to transfer power from the first pow input to the main load.

18. The engine of claim 13 , wherein the second power source is different from the first power input.

19. An engine, comprising:
it first power input and a second power input,
main load;
transmission engaged with and between the first power input, the second power input, and the main load, the transmission comprising:
an epicyclic gear train engaged with the first power input and selectively engageable with the

Assignees

• Pratt & Whitney Canada

Inventors

• Brito Roberto

Classifications

• F16H1/32

  in which the central axis of the gearing lies inside the periphery of an orbital gear · CPC title

• F05D2260/85

  Starting · CPC title

• F05D2220/325

  to drive unshrouded, high solidity propeller · CPC title

• F05D2260/40311

  of the epicyclical, planetary or differential type · CPC title

• B64D27/10

  of gas-turbine type  (jet aircraft B64D27/16) · CPC title