GAS TURBINE ENGINE WITH TRANSMISSION

• US 20140290265A1
• Filed: 01/30/2013
• Published: 10/02/2014
• Est. Priority Date: 01/30/2013
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Original Assignee: Pratt & Whitney Canada Corporation (Rtx Corporation)
• Inventors: MORGAN, Keith, DUBREUIL, Jean, MITROVIC, Lazar, DOOLEY, Kevin A., KENNY, Stephen, ULLYOTT, Richard, MEDVEDEV, Ilya, VINSKI, Johnny
• Granted Patent: US 10,094,295 B2
• Time in Patent Office: Days
• US Class Current: 60/773
• 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: F05D 2220/324 to drive unshrouded, low solidity propeller
• CPC Class Codes: F05D 2220/327 to drive shrouded, high solidity propeller

Abstract

A multi spool gas turbine engine with a differential having a selectively rotatable member which rotational speed determines a variable ratio between rotational speeds of driven and driving members of the differential. The driven member is engaged to the first spool and a rotatable shaft independent of the other spools (e.g. connected to a compressor rotor) is engaged to the driving member. First and second power transfer devices are engaged to the first spool and the selectively rotatable member, respectively. A circuit interconnects the power transfer devices and allows a power transfer therebetween, and a control unit controls the power being transferred between the power transfer devices. Power can thus be transferred between the first spool and the selectively rotatable member to change the speed ratio between the first spool and the rotatable shaft.

Claims

1. A gas turbine engine comprising:

at least two independently rotatable engine spools;

at least one turbine rotor drivingly engaged to a first one of the engine spools;

a differential having coupled members including a driven member, a driving member, and a selectively rotatable member with a rotational speed of the selectively rotatable member determining a variable ratio between rotational speeds of the driven and driving members, the driven member being drivingly engaged to the first spool;

a rotatable shaft drivingly engaged to the driving member and rotatable independently from all but the first of the engine spools;

a first power transfer device drivingly engaged to the first spool;

a second power transfer device drivingly engaged to the selectively rotatable member;

a circuit interconnecting the power transfer devices and allowing a power transfer therebetween; and

a control unit controlling the power being transferred between the power transfer devices through the circuit.

2. The gas turbine engine as defined in claim 1, wherein the rotatable shaft is drivingly engaged to a compressor rotor rotatable independently from all but the first of the engine spools.

3. The gas turbine engine as defined in claim 1, wherein the rotatable shaft is drivingly engaged to one element selected from the group consisting of a fan, a propeller, and an output shaft of the engine.

4. The gas turbine engine as defined in claim 1, wherein the first power transfer device is operable to both transfer power to and generate power from the first spool, and the second power transfer device is operable to both transfer power to and generate power from the selectively rotatable member.

5. The gas turbine engine as defined in claim 1, wherein the power transfer devices are electric machines and the circuit is an electric circuit, the control unit controlling electric power being transferred between the power transfer devices.

6. The gas turbine engine as defined in claim 1, wherein the power transfer devices are hydraulic machines and the circuit is a hydraulic circuit, the control unit controlling a flow of hydraulic fluid being transferred between the power transfer devices.

7. The gas turbine engine as defined in claim 6, wherein at least one of the first and second power transfer devices has a variable displacement.

8. The gas turbine engine as defined in claim 1, wherein the power transfer devices are pneumatic machines and the circuit is a pneumatic circuit, the control unit controlling a flow of compressed air being transferred between the power transfer devices.

9. The gas turbine engine as defined in claim 1, wherein the differential includes first and second coupled planetary gear systems, each system having a sun gear, a plurality of planet gears supported by a carrier around the sun gear and meshed therewith, and an annular ring gear around the planet gears and meshed therewith.

10. The gas turbine engine as defined in claim 9, wherein the carriers of the first and second systems are interconnected, the driven member is the sun gear of the first system, the driven member is the sun gear of the second system, the ring gear of one of the first and second systems is fixed, and the selectively rotatable member is the ring gear of the other of the first and second systems.

11. A gas turbine engine comprising:

a low pressure turbine located downstream of and in fluid communication with an exhaust of a high pressure section of the engine, the low pressure turbine having at least one turbine rotor;

a differential having coupled members including a driven member, a driving member, and a selectively rotatable member with a rotational speed of the selectively rotatable member determining a variable ratio between rotational speeds of the driven and driving members;

a low pressure shaft drivingly interconnecting each turbine rotor to the driven member;

a low pressure compressor located upstream of and having an exhaust in fluid communication with the high pressure section of the engine, the low pressure compressor having at least one compressor rotor drivingly interconnected to the driving member;

first means for transferring power at least one of to and from the low pressure shaft;

second means for transferring power at least the other of to and from the selectively rotatable member; and

a control unit connecting the first and second power transfer means and controlling power being transferred therebetween.

12. The gas turbine engine as defined in claim 11, wherein the first means for transferring power are means for selectively transferring power both to and from the low pressure shaft, and the second means for transferring powers are means for selectively transferring power both to and from the selectively rotatable member.

13. The gas turbine engine as defined in claim 11, wherein the first and second means for transferring power include first and second electric machines with at least one of the electric machines being operable as a generator and at least the other of the electric machines being operable as a motor, and the control unit controls electric power being transferred between the electric machines.

14. The gas turbine engine as defined in claim 11, wherein the first and second means for transferring power include first and second hydraulic machines with at least one of the hydraulic machines being operable as a pump and at least the other of the hydraulic machines being operable as a motor, and the control unit controls hydraulic power being transferred between the hydraulic machines.

15. The gas turbine engine as defined in claim 11, wherein the first and second means for transferring power include first and second pneumatic machines with at least one of the pneumatic machines being operable as a compressor and at least the other of the pneumatic machines being operable as a motor, and the control unit controls pneumatic power being transferred between the pneumatic machines.

16. The gas turbine engine as defined in claim 11, wherein the differential includes first and second coupled planetary gear systems, each system having a sun gear, a plurality of planet gears supported by a carrier around the sun gear and meshed therewith, and an annular ring gear around the planet gears and meshed therewith.

17. The gas turbine engine as defined in claim 16, wherein the carriers of the first and second systems are interconnected, the driven member is the sun gear of the first system, the driven member is the sun gear of the second system, the ring gear of one of the first and second systems is fixed, and the selectively rotatable member is the ring gear of the other of the first and second systems.

18. A method of adjusting a speed of a rotatable shaft of a gas turbine engine having a high pressure section including interconnected compressor and turbine rotors, the method comprising:

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

driving a rotation of the rotatable shaft with a power shaft through a variable transmission, the power shaft being driven by the at least one rotor of the low pressure turbine; and

transferring power between the power shaft and a rotational member of the transmission to change a ratio of rotational speeds between the rotatable shaft and the power shaft.

19. The method as defined in claim 18, wherein transferring power includes transferring power from the power shaft to the transmission to increase the rotational speed of the rotatable shaft and transferring power from the transmission to the power shaft to decrease the rotational speed of the rotatable shaft.

20. The method as defined in claim 18, wherein driving a rotation of the rotatable shaft includes driving a rotation of at least one rotor of a low pressure compressor located upstream of the high pressure section and coupled to the rotatable shaft.