# US 11,906,369 B2 · Overheat detection with clamp health monitoring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,369 B2 - Document ID: US11906369B2 - Status: Granted - Kind: B2 - Application number: 17/529,868 - Filed: 2021-11-18 - Published: 2023-03-23 - Granted: 2024-02-20 - Earliest claimed: 2021-09-22 - Assignees: Kidde Technologies, Inc. - Applicants: Kidde Technologies, Inc. - Inventors: Aswin Kumar Vallamkondu; Mark Sherwood Miller; Stefan Coreth - Web page: https://patentgrep.com/patent/US11906369B2 ## CPC - G01K 11/3206: at discrete locations in the fibre, e.g. using Bragg scattering - B64D 45/00: Aircraft indicators or protectors not otherwise provided for - G01H 9/004: {using fibre optic sensors (light guides per se G02B6/00, acousto-optical devices specially adapted for gating or modulating in optical wave guides G02F1/125)} - G01K 1/14: Supports; Fastening devices; Arrangements for mounting thermometers in particular locations - G01K 3/005: {Circuits arrangements for indicating a predetermined temperature (fire detection G08B17/00)} - B64D 2045/0085: {Devices for aircraft health monitoring, e.g. monitoring flutter or vibration} - B64D 2045/009: {Fire detection or protection; Erosion protection, e.g. from airborne particles} - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES ## Abstract A detection system in an aircraft includes an optical fiber arranged along a structure of the aircraft and affixed to the structure with clamps that are spaced apart along the structure. The optical fiber includes two or more sets of fiber Bragg gratings (FBGs). The system also includes a light source to generate light with two or more wavelengths for injection into the optical fiber, and processing circuitry to identify an overheat condition and monitor vibration experienced by the optical fiber based on reflected signals generated by the two or more sets of FBGs. Integrity of the clamps is indicated by monitoring the vibration. ## Claims ### Claim 1 A detection system in an aircraft comprising: an optical fiber arranged along a structure of the aircraft and affixed to the structure with clamps that are spaced apart along the structure, wherein the optical fiber includes two or more sets of fiber Bragg gratings (FBGs); a light source configured to generate light with two or more wavelengths for injection into the optical fiber; and processing circuitry configured to identify an overheat condition and monitor vibration experienced by the optical fiber based on reflected signals generated by the two or more sets of FBGs, wherein integrity of the clamps is indicated by monitoring the vibration; wherein each of the two or more FBGs of the optical fiber has a different grating pitch than others of the two or more FBGs and generates the reflected signals with a different reflected wavelength than the others of the two or more FBGs; and wherein the overheat condition and the vibration cause a shift in the reflected wavelength of the reflected signals produced by affected ones of the two or more FBGs, the shift being periodic over a predefined duration when based on the vibration and the shift being non-periodic over the predefined duration when based on the overheat condition. ### Claim 2 (depends on 1) The system according to claim 1, further comprising one or more photodetectors configured to detect an amplitude of the reflected signals at different wavelengths. ### Claim 3 (depends on 2) The system according to claim 2, further comprising a circulator configured to direct the light from the light source into the optical fiber and to direct the reflected signals to the one or more photodetectors. ### Claim 4 (depends on 1) The system according to claim 1, wherein the light source is configured to generate the light as pulses, with each pulse having one of the two or more wavelengths. ### Claim 5 (depends on 1) The system according to claim 1, wherein the optical fiber is first optical fiber, the system further comprising a second optical fiber arranged in parallel with the first optical fiber along the structure and affixed with the clamps. ### Claim 6 (depends on 5) The system according to claim 5, wherein the second optical fiber includes the two or more sets of FBGs. ### Claim 7 (depends on 6) The system according to claim 6, wherein the processing circuitry is configured to identify the first optical fiber to identify the overheat condition and the processing circuitry is configured to use the second optical fiber to identify the vibration. ### Claim 8 (depends on 1) The system according to claim 1, wherein the processing circuitry identifies a portion of the optical fiber that experiences the overheat condition or the vibration and one or more of the clamps that are affected based on identifying which of the two or more FBGs are the affected ones of the two or more FBGs. ### Claim 9 A method of assembling a detection system in an aircraft comprising: arranging an optical fiber along a structure of the aircraft and affixed to the structure with clamps that are spaced apart along the structure, wherein the optical fiber includes two or more sets of fiber Bragg gratings (FBGs); arranging a light source to generate light with two or more wavelengths for injection into the optical fiber; and configuring processing circuitry to identify an overheat condition and monitor vibration experienced by the optical fiber based on reflected signals generated by the two or more sets of FBGs, wherein integrity of the clamps is indicated by monitoring the vibration; wherein the arranging the optical fiber includes each of the two or more FBGs of the optical fiber having a different grating pitch than others of the two or more FBGs and generating the reflected signals with a different reflected wavelength than the others of the two or more FBGs; and wherein the configuring the processing circuitry to identify the overheat condition and monitor the vibration includes identifying that the overheat condition and the vibration cause a shift in the reflected wavelength of the reflected signals produced by affected ones of the two or more FBGs, the shift being periodic over a predefined duration when based on the vibration and the shift being non-periodic over the predefined duration when based on the overheat condition. ### Claim 10 (depends on 9) The method according to claim 9, further comprising arranging one or more photodetectors to detect an amplitude of the reflected signals at different wavelengths. ### Claim 11 (depends on 10) The method according to claim 10, further comprising arranging a circulator to direct the light from the light source into the optical fiber and to direct the reflected signals to the one or more photodetectors. ### Claim 12 (depends on 9) The method according to claim 9, wherein the arranging the light source includes configuring the light source to generate the light as pulses, with each pulse having one of the two or more wavelengths. ### Claim 13 (depends on 9) The method according to claim 9, wherein the optical fiber includes a first optical fiber and a second optical fiber, wherein arranging the optical fiber includes arranging the first and second optical fibers in parallel along the structure and affixed with the clamps. ### Claim 14 (depends on 13) The method according to claim 13, wherein the second optical fiber includes the two or more sets of FBGs. ### Claim 15 (depends on 14) The method according to claim 14, wherein the configuring the processing circuitry includes configuring the processing circuitry to use the first optical fiber to identify the overheat condition and configuring the processing circuit to use the second optical fiber to identify the vibration. ### Claim 16 (depends on 9) The method according to claim 9, wherein the configuring the processing circuitry includes the processing circuitry identifying a portion of the optical fiber that experiences the overheat condition or the vibration and one or more of the clamps that are affected based on identifying which of the two or more FBGs are the affected ones of the two or more FBGs.