# US 2013/0152600 A1 · Shaft break detection

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- Number: US 2013/0152600 A1
- Document ID: US20130152600A1
- Status: Published application
- Kind: A1
- Application number: 13/658,411
- Filed: 2012-10-23
- Published: 2013-06-20
- Earliest claimed: 2011-12-16
- Assignees: ROLLS-ROYCE plc
- Inventors: Arthur Laurence ROWE
- Web page: https://patentgrep.com/patent/US20130152600A1

## CPC

- F01D 21/00: Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
- F01D 17/04: responsive to load
- F01D 17/06: responsive to speed
- F01D 21/14: responsive to other specific conditions
- F05D 2270/091: in particular sudden load loss
- F05D 2270/304: Spool rotational speed
- G01M 15/14: Testing gas-turbine engines or jet-propulsion engines
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A method to detect shaft break includes monitoring first and second parameters and defining a two-dimensional parameter space that is a function of the first and second parameters, the two-dimensional parameter space includes integration regions. The method also includes defining an integration function for each integration region. For measured values of the first and second parameters, the method determines the applicable integration region and applies the integration function to the first parameter to give an integration result; and then sets a shaft break signal to TRUE when the integration result exceeds a predetermined threshold. The present invention also provides a shaft break detection system.

## Claims

### Claim 1

A method to detect shaft break comprising:
monitoring a first parameter and a second parameter;
defining a two-dimensional parameter space that is a function of the first and second parameters, the two-dimensional parameter space comprising integration regions;
defining an integration function for each integration region;
for measured values of the first and second parameters, determining the applicable integration region and applying the integration function to the first parameter to give an integration result; and
setting a shaft break signal to TRUE when the integration result crosses a predetermined threshold.

### Claim 2 (depends on 1)

A method as claimed in claim 1 wherein each of the first parameter and the second parameter comprises the derivative of a shaft speed.

### Claim 3 (depends on 2)

A method as claimed in claim 2 wherein the first parameter comprises the derivative of the shaft speed of the shaft to which the method is applied and the second parameter comprises the derivative of the shaft speed of a different shaft.

### Claim 4 (depends on 1)

A method as claimed in claim 1 wherein for one integration region the integration function comprises integrating over time the sum of the first parameter and a constant to saturate the integral.

### Claim 5 (depends on 1)

A method as claimed in claim 1 wherein for one integration region the integration function comprises integrating over time the first parameter.

### Claim 6 (depends on 1)

A method as claimed in claim 1 wherein for one integration region the integration function comprises no integration to freeze the integral.

### Claim 7 (depends on 1)

A method as claimed in claim 1 wherein the threshold is set to distinguish surge and shaft break events and is set within the range −15% to −30%.

### Claim 8 (depends on 1)

A control system comprising the method as claimed in claim 1.

### Claim 9 (depends on 1)

A gas turbine engine comprising the method as claimed in claim 1.

### Claim 10 (depends on 8)

A gas turbine engine comprising the control system as claimed in claim 8.

### Claim 11 (depends on 10)

A gas turbine engine as claimed in claim 10 wherein the method is applied to an intermediate pressure shaft system.

### Claim 12

A shaft break detection system comprising:
a first measurement device to measure a first parameter;
a second measurement device to measure a second parameter;
a two-dimensional parameter space defined as a function of the first and second parameters, the two-dimensional parameter space comprising integration regions;
a memory comprising an integration function for each integration region;
a processor to receive measured values of the first and second parameters from the first and second measurement devices, determine the applicable integration region from the two-dimensional parameter space and apply the integration function to obtain an integration result; and
a shaft break signal generator to generate a shaft break signal if the integration result crosses a predetermined threshold.

### Claim 13 (depends on 12)

A shaft break detection system as claimed in claim 12 wherein the first and second measurement devices are rotational speed sensors to measure a shaft speed.

### Claim 14 (depends on 12)

A shaft break detection system as claimed in claim 12 wherein the threshold is set to distinguish surge and shaft break events and is set in the range −15% to −30%.

### Claim 15 (depends on 12)

A control system comprising the shaft break detection system as claimed in claim 12.

### Claim 16 (depends on 12)

A gas turbine engine comprising a shaft break system as claimed in claim 12.

### Claim 17 (depends on 15)

A gas turbine engine comprising the control system as claimed in claim 15.

### Claim 18 (depends on 17)

A gas turbine engine as claimed in claim 17 wherein the first measurement device is coupled to an intermediate pressure shaft and the second measurement device is coupled to a high pressure shaft.

### Claim 19 (depends on 17)

A gas turbine engine as claimed in claim 17 further comprising a fuel shut-off mechanism coupled to the shaft break signal generator, the fuel shut-off mechanism arranged to shut off fuel supply to the engine in response to the shaft break signal.