# US 2019/0170012 A1 · Method and device for connecting fan rotor to low pressure turbine rotor

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- Number: US 2019/0170012 A1
- Document ID: US20190170012A1
- Status: Published application
- Kind: A1
- Application number: 15/832,814
- Filed: 2017-12-06
- Published: 2019-06-06
- Earliest claimed: 2017-12-06
- Assignees: General Electric Company
- Applicants: General Electric Company
- Inventors: Abhijeet Jayshingrao Yadav; Nicholas Joseph Kray; Nitesh Jain; Saurabh Sanjay Rasal
- Web page: https://patentgrep.com/patent/US20190170012A1

## CPC

- F01D 21/08: Restoring position
- F01D 21/045: {special arrangements in stators or in rotors dealing with breaking-off of part of rotor}
- F01D 25/16: Arrangement of bearings; Supporting or mounting bearings in casings (bearings per se F16C)
- F01D 25/162: {Bearing supports}
- F02C 3/107: with two or more rotors connected by power transmission
- F02C 7/06: Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M)
- 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)
- F02K 3/06: with front fan
- F16D 1/10: Quick-acting couplings in which the parts are connected by simply bringing them together axially
- F16D 3/18: the coupling parts (1) having slidably-interengaging teeth
- F16D 3/185: {radial teeth connecting concentric inner and outer coupling parts}
- F05D 2220/32: in gas turbines
- F05D 2230/60: Assembly methods
- F05D 2240/60: Shafts
- F05D 2250/241: spherical
- F05D 2250/25: helical
- F05D 2250/294: grooved
- F05D 2260/311: of the frangible or shear type
- F05D 2260/40: Transmission of power
- F05D 2260/403: through the shape of the drive components
- F16D 3/16: Universal joints in which flexibility is produced by means of pivots or sliding or rolling connecting parts
- F16D 2001/103: {the torque is transmitted via splined connections}
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)
- F16D: COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A rotor assembly includes a fan rotor shaft coupled to a fan rotor, a low pressure turbine rotor shaft coupled to a low pressure turbine rotor, and a joint device configured to connect the fan rotor shaft to the low pressure turbine rotor shaft, to allow torsion, shear and bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under normal operation, and allow torsion and shear but prevent bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under a fan blade-out event.

## Claims

### Claim 1

A rotor assembly comprising:
a fan rotor shaft coupled to a fan rotor;
a low pressure turbine rotor shaft coupled to a low pressure turbine rotor; and
a joint device configured to connect the fan rotor shaft to the low pressure turbine rotor shaft, to allow torsion, shear and bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under normal operation, and allow torsion and shear but prevent bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under a fan blade-out event.

### Claim 2 (depends on 1)

The rotor assembly according to claim 1, wherein the joint device is configured to allow angular misalignment between the fan rotor shaft and the low pressure turbine rotor shaft under the fan blade-out event.

### Claim 3 (depends on 1)

The rotor assembly according to claim 1, wherein the joint device comprises a load reduction joint selected from the group consisting of a spherical spline joint, a constant velocity universal joint, an axial coupling, or a combination thereof.

### Claim 4 (depends on 3)

The rotor assembly according to claim 3, wherein the joint device further comprises a cylindrical spline joint coupled to the load reduction joint.

### Claim 5 (depends on 1)

The rotor assembly according to claim 1, wherein the joint device comprises a spherical spline joint coupled to the fan rotor shaft, and a cylindrical spline joint coupled between the spherical spline joint and the low pressure turbine rotor shaft.

### Claim 6 (depends on 5)

The rotor assembly according to claim 5, wherein the spherical spline joint comprises spherical splines, and spherical spline grooves defined in the fan rotor shaft for accommodating the spherical splines.

### Claim 7 (depends on 5)

The rotor assembly according to claim 5, wherein the cylindrical spline joint comprises cylindrical splines and cylindrical spline grooves defined on an inner face of the spherical spline joint.

### Claim 8 (depends on 5)

The rotor assembly according to claim 5, wherein the joint device further comprises circumferentially-spaced mechanical fuses extending into both the fan rotor shaft and the spherical spline joint.

### Claim 9 (depends on 1)

The rotor assembly according to claim 1, wherein the joint device comprises a cylindrical spline joint coupled to the fan rotor shaft and a load reduction joint coupled between the cylindrical spline joint and the low pressure turbine rotor shaft, wherein the cylindrical spline joint comprises cylindrical splines and cylindrical spline grooves defined in the fan rotor shaft, and the load reduction joint is selected from the group consisting of a constant velocity universal joint and an axial coupling.

### Claim 10 (depends on 1)

The rotor assembly according to claim 1, further comprising:
a support frame;
a bearing assembly supporting the fan rotor shaft to the support frame; and
a cone shaft, comprising a conical cross-section and extending between the bearing assembly and the fan rotor shaft.

### Claim 11 (depends on 10)

The rotor assembly according to claim 10, wherein at least a part of the fan rotor shaft is sandwiched between the cone shaft and the joint device.

### Claim 12

A method for fabricating a rotor assembly for a gas turbine engine, the method comprising:
coupling a fan rotor shaft to a fan rotor;
coupling a low pressure turbine rotor shaft to a low pressure turbine rotor; and
connnecting the fan rotor shaft to the low pressure turbine rotor shaft through a joint device, which is configured to allow torsion, shear and bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under normal operation, and allow torsion and shear but prevent bending to be transferred between the fan rotor shaft and the low pressure turbine rotor shaft under a blade-out event.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the joint device is configured to allow angular misalignment between the fan rotor shaft and the low pressure turbine rotor shaft under the fan blade-out event.

### Claim 14 (depends on 12)

The method according to claim 12, wherein the joint device comprises a load reduction joint selected from the group consisting of a spherical spline joint, a constant velocity universal joint, an axial coupling, or a combination thereof.

### Claim 15 (depends on 14)

The method according to claim 14, wherein the joint device further comprises a cylindrical spline joint coupled to the load reduction joint.

### Claim 16 (depends on 12)

The method according to claim 12, wherein the joint device comprises a spherical spline joint coupled to the fan rotor shaft, and a cylindrical spline joint coupled between the spherical spline joint and the low pressure turbine rotor shaft.

### Claim 17 (depends on 16)

The rotor assembly according to claim 16, wherein the joint device further comprises circumferentially-spaced mechanical fuses extending into both the fan rotor shaft and the spherical spline joint.

### Claim 18 (depends on 12)

The method according to claim 12, wherein the joint device comprises a cylindrical spline joint coupled to the fan rotor shaft and a load reduction joint coupled between the cylindrical spline joint and the low pressure turbine rotor shaft, wherein the cylindrical spline joint comprises cylindrical splines and cylindrical spline grooves defined in the fan rotor shaft, and the load reduction joint is selected from the group consisting of a constant velocity universal joint and an axial coupling.

### Claim 19 (depends on 12)

The method according to claim 12, further comprising supporting the fan rotor shaft on a support frame with a bearing assembly, with a cone shaft extending between the bearing assembly and the fan rotor shaft, the cone shaft comprising a conical cross-section.

### Claim 20

A method for reducing unbalanced bearing loading of a gas turbine engine under a fan blade out (FBO) event, the engine comprising a fan rotor shaft coupled to a fan rotor and a low pressure turbine rotor shaft coupled to a low pressure turbine rotor, the method comprising:
operating the gas turbine engine in a normal mode, with the fan rotor shaft and the low pressure turbine rotor shaft connected in torsion, shear and bending; and
disconnecting the fan rotor shaft from the low pressure turbine rotor shaft in bending while maintaining the connection between the fan rotor shaft and the low pressure turbine rotor shaft in torsion and shear, when a blade-out event occurs.