초록 ▼

A gas turbine engine with a transmission having a variable ratio is discussed. A first gear train is in driving engagement with the low pressure spool and has a first output gear. A second gear train is in driving engagement with the high pressure spool and has a second output gear spaced apart from

A gas turbine engine with a transmission having a variable ratio is discussed. A first gear train is in driving engagement with the low pressure spool and has a first output gear. A second gear train is in driving engagement with the high pressure spool and has a second output gear spaced apart from the first output gear. A third gear train defines a driving engagement between the low pressure spool and the low pressure compressor rotor with a variable transmission ratio. A fourth gear train is in driving engagement with the first and second output gears, and in driving engagement with the third gear train to determine the transmission ratio. A method of adjusting a speed of a low pressure compressor rotor of a gas turbine engine is also discussed.

대표청구항 ▼

1. A gas turbine engine comprising: a core engine having a rotatable high pressure spool;a low pressure spool rotatable independently of the high pressure spool;a low pressure compressor rotor located upstream of the core engine; anda transmission having a variable transmission ratio and including:

1. A gas turbine engine comprising: a core engine having a rotatable high pressure spool;a low pressure spool rotatable independently of the high pressure spool;a low pressure compressor rotor located upstream of the core engine; anda transmission having a variable transmission ratio and including: a first gear train in driving engagement with the low pressure spool and having a first output gear,a second gear train in driving engagement with the high pressure spool and having a second output gear spaced apart from the first output gear,a third gear train defining a driving engagement between the low pressure spool and the low pressure compressor rotor, a ratio between rotational speeds of the low pressure spool and of the low pressure compressor rotor defining the variable transmission ratio, anda fourth gear train in driving engagement with the first and second output gears, the fourth gear train being in driving engagement with the third gear train and determining the transmission ratio. 2. The engine as defined in claim 1, wherein the first gear train includes an input sun gear connected to the low pressure spool, a plurality of planet gears meshed with the sun gear and retained by a fixed carrier, and a rotatable ring defining a first ring gear meshed with the planet gears, the first output gear being defined as a second ring gear forming part of the rotatable ring and spaced apart from the first ring gear. 3. The engine as defined in claim 1, wherein the second gear train includes an input sun gear connected to a shaft rotating with the high pressure spool, a plurality of planet gears meshed with the sun gear and retained by a fixed carrier, and a rotatable ring defining a first ring gear meshed with the planet gears, the second output gear being defined as a second ring gear forming part of the rotatable ring and spaced apart from the first ring gear. 4. The engine as defined in claim 1, wherein the third gear train includes an input sun gear connected to the low pressure spool, a first plurality of planet gears meshed with the input sun gear and retained by a rotatable carrier, a fixed ring gear meshed with the first plurality of planet gears, a second plurality of planet gears supported by the rotatable carrier and rotatable independently of the first plurality of planet gears, and an output sun gear connected to a shaft of the low pressure compressor rotor and meshed with the second plurality of planet gears. 5. The engine as defined in claim 4, further comprising a clutch operable to selectively allow and prevent the meshed engagement between the first plurality of planet gears and the input sun gear. 6. The engine as defined in claim 4, wherein the first gear train includes the input sun gear connected to the low pressure spool, the first plurality of planet gears meshed with the input sun gear and retained by the rotatable carrier, and the fixed ring gear meshed with the first plurality of planet gears, the first output gear being defined as a ring gear forming part of the rotatable carrier. 7. The engine as defined in claim 1, wherein the fourth gear train includes a control gear meshed with the first and second output gears and a rotatable ring supporting the control gear, the control gear and rotatable ring being rotatable about perpendicular axes, the rotatable ring being in driving engagement with the third gear train intermediate an input gear and an output gear thereof. 8. The engine as defined in claim 4, wherein the fourth gear train includes a control gear meshed with the first and second output gears and a rotatable ring supporting the control gear, the control gear and rotatable ring being rotatable about perpendicular axes, the rotatable ring defining a ring gear meshed with the second plurality of planet gears. 9. The engine as defined in claim 7, wherein the control gear is a stepped gear including two interconnected gears having different sizes, the first and second output gears being meshed with different ones of the interconnected gears. 10. The engine as defined in claim 7, wherein the control gear is a single gear received between and in meshed engagement with the first and second output gears. 11. A gas turbine engine comprising: a core engine having a rotatable high pressure spool;a low pressure spool rotatable independently of the high pressure spool;a low pressure compressor rotor located upstream of the core engine; anda transmission having a variable transmission ratio and including: a control gear rotationally supported on a rotatable control ring, with rotational axes of the control gear and of the control ring being perpendicular to one another,a first rotatable ring gear meshed with the control gear and in driving engagement with the low pressure spool,a second rotatable ring gear meshed with the control gear and in driving engagement with the high pressure spool, anda gear train having an input gear in driving engagement with the low pressure spool and an output gear in driving engagement with the low pressure compressor rotor, the control ring being in driving engagement with at least one gear of the gear train. 12. The engine as defined in claim 11, further comprising a clutch operable to selectively engage and disengage the input gear from a remainder of the gear train. 13. The engine as defined in claim 11, wherein the first rotatable ring gear is meshed with a plurality of planet gears retained by a fixed carrier, the planet gears being meshed with a sun gear connected to the low pressure spool. 14. The engine as defined in claim 11, wherein the second rotatable ring gear is meshed with a plurality of planet gears retained by a fixed carrier, the planet gears being meshed with a sun gear connected to a shaft driven by the high pressure spool. 15. The engine as defined in claim 11, wherein the input gear of the gear train is a sun gear connected to the low pressure spool, the gear train including a first plurality of planet gears meshed with the sun gear and retained by a rotatable carrier, a fixed ring gear meshed with the first plurality of planet gears, and a second plurality of planet gears supported by the rotatable carrier and meshed with a control ring gear forming part of the control ring, the output gear of the gear train being a sun gear connected to a shaft of the low pressure compressor rotor and meshed with the second plurality of planet gears. 16. The engine as defined in claim 15, wherein the first rotatable ring gear is defined as part of the rotatable carrier and is in driving engagement with the low pressure spool through the meshed engagement of the first plurality of planet gears with the sun gear connected to the low pressure spool. 17. The engine as defined in claim 11, wherein the control gear is a single gear received between and in meshed engagement with the first and second rotatable ring gears. 18. The engine as defined in claim 11, wherein the control gear including two interconnected gears having different sizes, the first and second rotatable ring gears being each meshed with a respective one of the interconnected gears. 19. A method of adjusting a speed of a low pressure compressor rotor of a gas turbine engine having low and high pressure spools free to rotate independently from one another, the method comprising: rotating the low pressure spool at a first rotational speed;driving a rotation of the low pressure compressor rotor with the low pressure spool through a first portion of a transmission such that the low pressure compressor rotor rotates at a second rotational speed, the first portion defining a variable ratio between the first and second rotational speeds;rotating the high pressure spool at a third rotational speed; andadjusting the variable ratio through a driving engagement of a second portion of the transmission with the first portion, the second portion being drivingly engaged with the low and high pressure spools such that the variable ratio is adjusted based on a difference between the first and third rotational speeds. 20. The method as defined in claim 19, wherein adjusting the variable ratio includes rotating a first gear with the low pressure spool, rotating a second gear with the low pressure spool, rotating a control ring and a control gear rotationally supported thereon about perpendicular rotational axes with the first and second gears, and changing a rotational speed of at least one gear of the first portion with the control ring.