Gas turbine engine with transmission and method of adjusting rotational speed

• US 9,752,500 B2
• Filed: 03/14/2013
• Issued: 09/05/2017
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Ullyott, Richard, Mitrovic, Lazar, Dubreuil, Jean, Kenny, Stephen Christopher, Bouchard, Guy, Medvedev, Ilya B., Morgan, Keith, Karanjia, Darius Jehangir, Youssef, Nashed Azer
• Primary Examiner(s): Pho, Pascal M Bui
• Assistant Examiner(s): Linderman, Eric
• Application Number:
  US13/804,799
• Publication Number:
  US 20140260295A1
• Time in Patent Office: 1,636 Days
• Field of Search: 476 50, 476 46, 476 40
• CPC Class Codes: F02C 3/107 with two or more rotors connected by power transmission
• CPC Class Codes: F02C 3/113 with variable power transmission between rotors
• CPC Class Codes: F02C 7/36 Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user F02C3/107 - F02C3/13 and F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H
• CPC Class Codes: F02C 9/56 with power transmission control
• CPC Class Codes: F05D 2260/4031 as in toothed gearing

Abstract

A gas turbine engine including at least one high pressure turbine rotor and at least one high pressure compressor rotor drivingly engaged to a rotatable high pressure spool, a low pressure spool rotatable independently of the high pressure spool, at least one low pressure turbine rotor drivingly engaged to the low pressure spool, and a rotatable load drivingly engaged to the low pressure spool. A fixed rotational speed ratio is defined between rotational speeds of the at high pressure turbine and compressor rotors. A fixed rotational speed ratio is defined between rotational speeds of the low pressure turbine rotor(s) and of the low pressure spool. A low pressure compressor rotor is in driving engagement with the low pressure spool through a variable transmission which defines a variable rotational speed ratio between the rotational speeds of the low pressure spool and of the low pressure compressor rotor.

Claims

1. A method of adjusting a rotational speed of at least one low pressure compressor rotor of a gas turbine engine having independently rotatable low pressure and high pressure spools, the method comprising:

rotating at least one rotor of a high pressure compressor of a core section of the engine with at least one rotor of a high pressure turbine of the core section through the high pressure spool;

rotating at least one rotor of a low pressure turbine with a flow of exhaust gases from the high pressure turbine section;

rotating the low pressure spool with the at least one rotor of the low pressure turbine;

rotating a load of the engine with the low pressure spool;

driving a rotation of the at least one low pressure compressor rotor with the low pressure spool through a continuously variable transmission defining a variable transmission ratio between rotational speeds of the at least one low pressure compressor rotor and of the low pressure spool, the continuously variable transmission including a first drive member coupled to the low pressure spool, a second drive member coupled to the at least one low pressure compressor rotor, at least one movable member drivingly engaged to the first and second drive members and having a relative position with respect to the first and second drive members, and an actuation mechanism connected to the at least one movable member; and

adjusting the transmission ratio to obtain a desired rotational speed for the low pressure compressor rotor by varying the relative position of the at least one movable member with the actuation mechanism, the relative position determining a variable rotational speed ratio between the rotational speeds of the first and second drive members.

2. The method according to claim 1, wherein the load is rotated at a constant or substantially constant rotational speed.

3. The method according to claim 1, wherein the method is repeated over a period of time and the desired rotational speed and transmission ratio are varied over the period of time.

4. The method according to claim 1, wherein adjusting the transmission ratio includes changing an orientation of the at least one moveable member.

5. The method according to claim 4, wherein changing the orientation of the at least one movable member includes varying a relative pressure between two oil galleries defined on opposed sides of a part of a piston engaged to the moveable member.

6. The method according to claim 1, wherein the at least one rotor of the high pressure compressor, the at least one rotor of a high pressure turbine and the high pressure spool are rotated at a same rotational speed, and the at least one rotor of the low pressure turbine is rotated at a same rotational speed as that of the low pressure spool.

7. A method of adjusting rotational speeds of a gas turbine engine having independently rotatable low pressure and high pressure spools, the method comprising:

selecting a first rotational speed for at least one high pressure compressor rotor and at least one high pressure turbine rotor of a core of the gas turbine engine;

rotating the at least one high pressure compressor rotor with the at least one high pressure turbine rotor through the high pressure spool at the first rotational speed, a ratio between the first rotational speed and a rotational speed of the high pressure spool having a fixed value;

selecting a second rotational speed for a load of the engine;

selecting a third rotational speed for at least one low pressure compressor rotor of the engine; and

adjusting a variable ratio of a continuously variable transmission including a first drive member coupled to the low pressure spool, a second drive member coupled to the at least one low pressure compressor rotor, at least one movable member drivingly engaged to the first and second drive members and having a relative position with respect to the first and second drive members, and an actuation mechanism connected to the at least one movable member, the variable ratio being adjusted to rotate the at least one low pressure compressor rotor at the third rotational speed while rotating the load at the second rotational speed with at least one low pressure turbine rotor of the engine through the low pressure spool, the variable ratio being adjusted by varying the relative position of the at least one movable member with the actuation mechanism, the relative position determining a variable rotational speed ratio between the rotational speeds of the first and second drive members, a ratio between the second rotational speed and a rotational speed of the low pressure spool having a fixed value.

8. The method according to claim 7, wherein the first rotational speed is selected to obtain a desired fuel consumption for the engine.

9. The method according to claim 7, wherein the first rotational speed is selected based on a power demand on the engine.

10. The method according to claim 7, wherein the method is repeated over a period of time and the second rotational speed remains constant while the third rotational speed is varied.

11. The method according to claim 7, wherein the third rotational speed is selected based on desired exhaust pressure of the low pressure compressor.

12. The method according to claim 7, wherein adjusting a variable ratio of the transmission includes changing an orientation of the at least one movable member.

13. The method according to claim 12, wherein changing the orientation of the at least one movable member includes varying a relative pressure between two oil galleries defined on opposed sides of a part of a piston connected to the moveable member.

14. The method according to claim 7, wherein the ratio between the first rotational speed and the rotational speed of the high pressure spool is 1, and the ratio between the second rotational speed and the rotational speed of the low pressure spool is 1.

15. A gas turbine engine comprising:

a core engine having at least one high pressure turbine rotor and at least one high pressure compressor rotor connected to a high pressure spool such as to be in driving engagement therewith, the high pressure spool being rotatable, a first fixed rotational speed ratio being defined between a rotational speed of the at least one high pressure turbine rotor and a rotational speed of the at least one high pressure compressor rotor;

a low pressure spool rotatable independently of the high pressure spool;

at least one low pressure turbine rotor connected to the low pressure spool such as to be in driving engagement therewith, a second fixed rotational speed ratio being defined between a rotational speed of the at least one low pressure turbine rotor and a rotational speed of the low pressure spool, the at least one low pressure turbine rotor in fluid communication with the at least one high pressure turbine rotor;

a rotatable load in driving engagement with the low pressure spool, a third fixed rotational speed ratio being defined between a rotational speed of the rotatable load and the rotational speed of the low pressure spool; and

a low pressure compressor rotor in fluid communication with the at least one high pressure compressor rotor, the low pressure compressor rotor being in driving engagement with the low pressure spool through a continuously variable transmission, the continuously variable transmission defining a variable rotational speed

ratio between the rotational speed of the low pressure spool and a rotational speed of the low pressure compressor rotor, the continuously variable transmission including a first drive member coupled to the low pressure spool, a second drive member coupled to the low pressure compressor, at least one movable member drivingly engaged to the first and second drive members, and an actuation mechanism connected to the at least

one movable member, the at least one movable member having a relative position with respect to the first and second drive members, the relative position being variable, the relative position determining a variable rotational speed ratio between the rotational speeds of the first and second drive members, and the actuation mechanism determining the relative position.

16. The engine as defined in claim 15, wherein the at least one high pressure turbine rotor and the at least one high pressure compressor rotor are directly connected to the high pressure spool such as to be rotatable therewith at a same rotational speed, and the at least one low pressure turbine rotor is directly connected to the low pressure spool such as to be rotatable therewith at a same rotational speed.

17. The engine as defined in claim 15, wherein the first and second drive members are defined as first and second drive discs with toroidal surfaces facing each other in a spaced apart manner, at least one of the first and second drive discs being axially moveable, the first and second drive discs being biased toward one another and in engagement with the at least one moveable member.

18. The engine as defined in claim 17, wherein the at least one movable member includes a plurality of idler discs each in driving engagement with the toroidal surface of each of the first and second drive discs, the actuation mechanism controlling an angle of the plurality of idler discs with respect to the toroidal surface of each of the first and second drive discs.

19. The engine as defined in claim 15, wherein the rotatable load is selected from the group consisting of a fan, a propeller and an output shaft.