Bearing load sharing system

Abstract

A bearing load sharing system comprising: first and second rotors extending in an axial direction; a first thrust bearing having an inner race and an outer race, the inner race connected to the first rotor; a second thrust bearing having an inner race and an outer race, the inner race connected to the second rotor; and an inter-rotor bearing having an inner race and an outer race, the inner race connected to one of the first and second rotor and the outer race connected to the other of the first and second rotor; wherein the outer race of the first bearing and/or the outer race of the second bearing is movable to vary the axial spacing between the outer races.

Claims

1. A bearing load sharing system comprising: first and second rotors extending in an axial direction; a first thrust bearing having an inner race and an outer race, the inner race connected to the first rotor; a second thrust bearing having an inner race and an outer race, the inner race connected to the second rotor; and an inter-rotor bearing having an inner race and an outer race, the inner race connected to one of the first and second rotor and the outer race connected to the other of the first and second rotor; wherein at least one of the outer race of the first thrust bearing and the outer race of the second thrust bearing is movable to vary axial spacing between the outer race of the first thrust bearing and the outer race of the second thrust bearing so as to transfer axial load between the first thrust bearing on the first rotor and the second thrust bearing on the second rotor.

2. The system according to claim 1 wherein: the first rotor is a low pressure rotor extending from an upstream fan to a downstream low pressure turbine; the second rotor is an intermediate pressure rotor extending from an upstream intermediate pressure compressor to a downstream intermediate pressure turbine; the first thrust bearing is a low pressure load-share thrust bearing (LP1); and the second thrust bearing is a first intermediate pressure load-share thrust bearing (IP1).

3. The system according to claim 2 wherein the intermediate pressure load-share thrust bearing (IP1) is downstream from the low pressure load-share thrust bearing (LP1).

4. The system according to claim 3 wherein the low pressure load-share thrust bearing (LP1) is positioned on the low pressure rotor proximal the fan and the intermediate pressure load-share thrust bearing (IP1) is positioned on the intermediate rotor at the upstream axial end of the intermediate pressure compressor.

5. The system according to claim 2 wherein the low pressure load-share thrust bearing (LP1) and the intermediate pressure load-share thrust bearing (IP1) are substantially axially aligned.

6. The system according to claim 2 wherein the inter-rotor bearing is a low pressure inter-rotor thrust bearing (LP2), the inner race of the inter-rotor bearing is connected to the low pressure rotor, and the outer race of the inter-rotor bearing is connected to the intermediate pressure rotor.

7. The system according to claim 1 wherein: the first rotor is a high pressure rotor extending from an upstream high pressure compressor to a downstream high pressure turbine; the second rotor is an intermediate pressure rotor extending from an upstream intermediate pressure compressor to a downstream intermediate pressure turbine; the first thrust bearing is a high pressure load-share thrust bearing (HP1); and the second thrust bearing is an intermediate pressure load-share thrust bearing (IP2).

8. The system according to claim 7 wherein the high pressure load-share thrust bearing (HP1) is downstream from the intermediate pressure load-share thrust bearing (IP2).

9. The system according to claim 8 wherein the high pressure load-share thrust bearing (HP1) is positioned on the high pressure rotor proximal and upstream from the high pressure compressor and the intermediate pressure load-share thrust bearing (IP2) is positioned on the intermediate pressure rotor proximal the downstream axial end of the intermediate pressure compressor.

10. The system according to claim 7 wherein the high pressure load-share thrust bearing (HP1) and the intermediate pressure load-share bearing (IP2) are substantially axially aligned.

11. The system according to claim 7 wherein the inter-rotor bearing is a high pressure inter-rotor thrust bearing (HP2), the inner race of the inter-rotor bearing is connected to the intermediate pressure rotor, and the outer race of the inter-rotor bearing is connected to the high pressure rotor.

12. A gas turbine engine having the bearing load sharing system according to claim 1.

13. The system according to claim 1 wherein the outer races of the first and second thrust bearings are flexibly connected by a hydraulic connection to effect movement of the at least one of the outer race of the first thrust bearing and the outer race of the second thrust bearing.

14. A bearing load sharing system comprising: first and second rotors extending in an axial direction; a first thrust bearing having an inner race and an outer race, the inner race connected to the first rotor; a second thrust bearing having an inner race and an outer race, the inner race connected to the second rotor; an inter-rotor bearing having an inner race and an outer race, the inner race connected to the first rotor and the outer race connected to the second rotor; a third rotor extending in an axial direction; a third bearing having an inner race and an outer race, the inner race connected to the second rotor; a fourth bearing having an inner race and an outer race, the inner race connected to the third rotor; and a second inter-rotor bearing having an inner race and an outer race, the inner race connected to the second rotor, and the outer race connected to the third rotor, wherein at least one of the outer race of the first thrust bearing and the outer race of the second thrust bearing is movable to vary axial spacing between the outer race of the first thrust bearing and the outer race of the second thrust bearing so as to transfer axial load between the first thrust bearing on the first rotor and the second thrust bearing on the second rotor.

15. The system according to claim 14 wherein: the first rotor is a low pressure rotor extending from an upstream fan to a downstream low pressure turbine; the second rotor is an intermediate pressure rotor extending from an upstream intermediate pressure compressor to a downstream intermediate pressure turbine; the third rotor is a high pressure rotor extending from an upstream high pressure compressor to a downstream high pressure turbine; the first thrust bearing is a low pressure load-share thrust bearing (LP1); the second thrust bearing is a first intermediate pressure load-share thrust bearing (IP1); the third bearing is a second intermediate pressure load-share bearing (IP2); and the fourth bearing is a high pressure load-share thrust bearing (HP1).

16. The system according to claim 14 wherein the outer races of the first and second thrust bearings and/or the third and fourth bearings are flexibly connected by a hydraulic connection to effect movement of one or both of the outer races.

17. The system according to claim 14 wherein the outer races of the first and second thrust bearings and/or the third and fourth bearings are flexibly connected by a compliant element to effect movement of one or both of the outer races.

Description

BRIEF DESCRIPTION

(1) Embodiments will now be described by way of example with reference to the accompanying drawings in which:

(2) FIG. 1 shows a prior art ducted fan gas turbine engine;

(3) FIG. 2 shows an axial cross-section through a portion of a prior art ducted fan gas turbine engine;

(4) FIGS. 3 and 4 show an axial cross-section through a portion of a gas turbine engine having a bearing load share system according to a first embodiment;

(5) FIGS. 5 and 6 show an axial cross-section through a portion of a gas turbine engine having a bearing load share system according to a second embodiment; and

(6) FIGS. 7 and 8 show an axial cross-section through a portion of a gas turbine engine having a bearing load share system according to a third embodiment.

DETAILED DESCRIPTION

(7) FIGS. 3 and 4 show an axial cross-section through a gas turbine engine having a bearing load sharing system according to a first embodiment.

(8) The gas turbine engine comprises three concentric rotors.

(9) The innermost rotor is the low pressure (LP) rotor 30 and this connects the LP turbine 18 to the fan 12. The LP rotor 30 is the longest rotor and has the smallest diameter.

(10) The next innermost rotor is the Intermediate Pressure (IP) rotor 26 which connects the IP compressor 13 to the IP turbine 17. This rotor 26 has a smaller diameter and is longer than the outermost rotor which is the High Pressure (HP) rotor 20 also known as the HP compressor drive cone. This HP rotor 20 connects the HP compressor 14 with the HP turbine 16.

(11) The bearing load sharing system comprises a low pressure load share thrust bearing (LP1) having an inner race and an outer race, the inner race connected to the LP rotor 30.

(12) The bearing load sharing system further comprises an intermediate pressure load share thrust bearing (IP1) having an inner race and an outer race, the inner race connected to the IP rotor 26.

(13) The IP1 thrust bearing is downstream from the LP1 thrust bearing.

(14) The LP1 thrust bearing is positioned on the LP rotor 30 proximal the fan 12 and the IP1 thrust bearing is positioned on the IP rotor 26 at the upstream axial end of the IP compressor 13.

(15) The outer races of the LP1 thrust bearing and IP1 thrust bearing are flexible joined via a hydraulic connection 35 such that the outer race of the LP1 thrust bearing and/or the outer race of the IP1 thrust bearing is movable to vary the axial spacing between their outer races.

(16) By providing outer races that are moveable relative to one another, it is possible to transfer axial load between the LP1 and IP1 thrust bearings on the LP and IP rotors such that the load carried by each can be tailored to suit the physical and/or operational constraints on the rotors. This allows the bearing with the greatest capacity to carry the greater load and, conversely, reduces the load on the bearing with the lower capacity (e.g. due to space or rotor speed constraints). Where the LP1 and IP1 thrust bearings are joined by a hydraulic connection 35, the force transfer can be varied in proportion to the effective piston areas of the outer races. If the effective piston areas are equal, the axial loads will be equally shared between the LP1 and IP1 thrust bearings.

(17) The system further comprises a low pressure inter-rotor thrust bearing (LP2) which comprises an inner race connected to the LP rotor 30 and an outer race connected to the IP rotor 26. Thus, axial loads can be transferred between the LP and IP rotors 30, 26 through the LP2 inter-rotor bearing. The load on the LP2 bearing will be the difference between the thrust loads applied to the LP and IP rotors 30, 26.

(18) The LP2 bearing is downstream from the LP1 thrust bearing i.e. closer to the LP turbine 18 than the LP1 thrust bearing.

(19) The LP2 bearing is positioned on the LP rotor 30 proximal the downstream axial end of the IP compressor 13.

(20) The system further comprises a low pressure radial bearing 33 which comprises an inner race connected to the LP rotor.

(21) The low pressure radial bearing 33 is downstream from the LP2 bearing and is positioned on the LP rotor 30 proximal the LP turbine 18.

(22) The system further comprises an intermediate pressure radial bearing (IP2) which comprises an inner race connected to the IP rotor 26.

(23) The IP2 thrust bearing is downstream from the IP1 thrust bearing i.e. closer to the IP turbine 17 than the IP1 thrust bearing and is positioned on the IP rotor 26 proximal the upstream axial end of the IP compressor 13.

(24) The system further comprises a downstream intermediate pressure radial bearing (IP3) having an inner race connected to the IP rotor 26.

(25) The IP3 bearing is downstream from the IP2 thrust bearing and is mounted on the IP rotor 26 proximal the IP turbine 17.

(26) FIGS. 5 and 6 show an axial cross-section through a gas turbine engine having a bearing load sharing system according to a second embodiment.

(27) In this embodiment, the system comprises a high pressure load-share thrust bearing (HP1) having an inner race connected to the HP rotor 20 and an intermediate pressure load-share thrust bearing (IP2) having an inner race connected to the IP rotor 26.

(28) In this embodiment, the total IP and HP forces are split between the IP2 and HP1 bearings,

(29) The HP1 thrust bearing is a stacked, multiple row bearing.

(30) The HP1 thrust bearing may be downstream from the IP2 thrust bearing.

(31) The HP1 thrust bearing is positioned on the HP rotor 20 proximal and upstream from the high pressure compressor 14 and the IP2 thrust bearing is positioned on the IP rotor 26 proximal the downstream axial end of the IP compressor 13.

(32) The HP1 thrust bearing and IP2 thrust bearing are substantially axially aligned.

(33) The system further comprises a high pressure inter-rotor thrust bearing (HP2) which comprises an inner race connected to the IP rotor 26 and an outer race connected to the HP rotor 30. This allows transfer of axial load on the HP rotor to the IP rotor and vice versa.

(34) The HP2 bearing is downstream from the HP1 thrust bearing and is mounted proximal the HP turbine 16.

(35) FIGS. 7 and 8 show an axial cross-section through a gas turbine engine having a bearing load sharing system according to a third embodiment. This embodiment is a combination of the first and second embodiments described above.

(36) The first rotor is the low pressure (LP) rotor 30, the second rotor is the intermediate pressure (IP) rotor 26 and the third rotor is the high pressure (HP) rotor 20.

(37) The first bearing is the low pressure bearing (LP1), the second bearing is a first intermediate pressure bearing (IP1), the third bearing is a second intermediate pressure load-share bearing (IP2) and the fourth bearing is the high pressure load share-thrust bearing (HP1).

(38) In this embodiment, the LP, IP and HP thrust loads are shared between all three rotors

(39) The locations and relative positions of the LP1, IP1, IP2 and HP1 thrust bearings are as described above for the first and second embodiments.

(40) The system further comprises a high pressure inter-rotor thrust bearing (HP2) which comprises an inner race connected to the IP rotor 26 and an outer race connected to the HP rotor 30 and a low pressure inter-rotor thrust bearing (LP2) which comprises an inner race connected to the IP rotor 26 and an outer race connected to the LP rotor 30.

(41) The locations and relative positions of the HP2 and LP2 thrust bearings are as described for the first and second embodiments.

(42) While the bearing load sharing system has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the scope of the claims.

(43) All references referred to above are hereby incorporated by reference.