Galvanically isolated gas sensor system for aerospace applications

Abstract

An aircraft detection system includes a power and communications module, a sensor module in optical communication with said module, located in a space that is at least partially enclosed within the aircraft, and at least one gas sensor in communication with the sensor module, located in the same space. The gas sensor is configured to detect at least one flammable or non-flammable gas, and both the sensor module and the gas sensor are galvanically isolated from the power and communications module.

Description

BACKGROUND

[0001] The present disclosure relates to sensors, and more particularly to galvanically isolated sensors.

[0002] Gas sensors, like other electronics for aerospace applications, typically transmit data and / or are powered through copper wiring. Unlike sensing of non-flammable gases (e.g., carbon dioxide), sensing of flammable gases (e.g., carbon monoxide, hydrogen, and other hydrocarbons) for aerospace applications requires galvanic isolation to remove possible ignition sources, which is crucial for aviation safety. Optical fibers are particularly well-suited for aerospace applications since they do not transmit electrical signals, and can also be smaller, lighter, resistant to electromagnetic and radio frequency interference, and more durable than copper wiring. The present invention is characterised over US 2017 / 268974 A1, which discloses apparatus and associated methods that relate to suppressing electrical arcing within a fuel tank in which a fuel density sensor is located. US 2023 / 120640 A1 discloses an optically powered sensing system for a hazardous environment, such as a coal mine.SUMMARY

[0003] An aircraft sensing system includes a power and communications module, a sensor module in optical communication with the power and communications module, the sensor module being disposed in an at least partially enclosed space within the aircraft, and at least one gas sensor in communication with the sensor module, the at least one gas sensor being disposed in the at least partially enclosed space. The at least one gas sensor is configured to sense at least one flammable gas species or non-flammable gas species, and the sensor module and the at least one gas sensor are galvanically isolated from the power and communications module.

[0004] A method of monitoring a gas species on an aircraft includes sending, via a power and communications module, an optical power signal to a sensor module, powering, via the sensor module, at least one gas sensor, and sensing, via the at least one gas sensor, the gas species with an at least partially enclosed space aboard the aircraft. The gas species is a flammable gas species or a non-flammable gas species.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a schematic illustration of a gas sensing system for an aircraft. FIG. 2 is a schematic illustration of a sensor module and sensor belonging to the gas sensing system of FIG. 1.

[0006] While the above-identified figures set forth one or more embodiments of the present disclosure, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings.DETAILED DESCRIPTION

[0007] This disclosure presents galvanically isolated sensor systems for sensing flammable and / or otherwise harmful gases. The gas sensors can preferably be used in aerospace applications, as is described below, although they can also be used in other vehicles and stationary structures.

[0008] FIG. 1 is a schematic illustration of sensing system 10. FIG. 2 is a schematic illustration of sensor module 14 and sensor 16 of system 10. FIGS. 1 and 2 are discussed together.

[0009] System 10 can include power and communications module (PCM) 12, sensor module (SM) 14, and at least one sensor 16. As shown in FIG. 1, system 10 includes optional second and third sensors 16, and can generally include 1 to n sensors, as limited by spatial constraints, power requirements, etc. PCM 12 can be used to power sensor 16 by converting electrical power from a power source (e.g., an aircraft battery) received via input line 18. The power source can provide, in some embodiments, 12 volts, 24 volts, or 48 volts of DC power to PCM 12. In an alternative embodiment, the power source can instead be a source of AC power. PCM 12 converts the voltage into an optical signal (e.g., as a laser) which can be provided to SM 14 via optical power line 20. Transceiver (TX) line 22 and receiver (RX) line 24 allow PCM 12 to bidirectionally communicate with SM 14, that is transmitting and receiving, respectively, data signals to / from SM 14. Accordingly, lines 20, 22, and 24 can all be fiber optic cables transmitting optical, and non-electrical signals. In an alternative embodiment, TX line 22 and RX line 24 can be incorporated into a single RX / TX line, instead of two distinct lines. In yet another alternative embodiment, the functions of lines 20, 22, and 24 can all be carried out by a single fiber optic cable configured for both power and data transmission.

[0010] SM 14 can include power converter 26 to convert the optical power signal back to an electrical signal to power any associated sensors 16. In this regard, SM 14 provides voltage isolated regulated power to sensor 16. In one embodiment, power converter 26 can be a photovoltaic cell. As shown in FIG. 2, sensor 16 can be collocated with SM 14, and in some embodiments, mounted on SM 14. SM 14 can further include signal conditioner 28 for formatting sensor 16 signals to be read / converted by analog-to-digital converter (ADC) 30 of SM 14.

[0011] Sensor 16 can be configured to sense / detect at least one gas species, including flammable species, such as hydrogen (H 2 ), carbon monoxide (CO), and other hydrocarbon gases within an at least partially enclosed space 32 of an aircraft. Space 32 can be, for example a cargo bay, the ullage space of a fuel tank, and / or proximate a fuel nozzle within the aircraft's engine. System 32 is configured such electrical power is not transmitted through space 32, rather, PCM 12 is disposed elsewhere on the aircraft (i.e., outside of space 32). Stated another way, SM 14 and sensor(s) 16 are galvanically isolated from the rest of system 10, receiving power only optically, and non-electrically from PCM 12. Sensor 16 can additionally and / or alternatively be configured to sense non-flammable, toxic species, or asphyxiant species, such as carbon dioxide (CO 2 ). As such, space 32 can further include a cabin or cockpit, where people might be present. Sensor 16 can be an electrochemical, metal oxide, catalytic bead, or optical sensor, depending on the sensing requirements. For example, electrochemical, metal oxide, and catalytic bead sensing modalities can all be used for hydrogen sensing. Sensor 16 can be a relatively low power sensor, with electrochemical modalities requiring only milliwatts of power, and the other modalities requiring watts. Sensed information can be conditioned then converted by signal conditioner 28 and ADC 30, and can be sent to PCM 12 via RX line 24. PCM 12 can communicate sensed data to the aircraft control system or other controller via universal serial bus (USB) or controller area network (CAN) bus 34.

[0012] In an alternative embodiment with multiple sensors 16, each sensor 16 can be collocated with its own SM 14, or with a common SM 14 as schematically represented in FIG. 1. More specifically, if system 10 includes multiple sensors 16 in close proximity to one another, a single SM 14 can support the multiple sensors 16. If multiple sensors 16 are instead disposed relatively far apart from one another, a corresponding number of SMs 14 may be preferable. Each sensor can be located in a single space 32 (e.g., a cargo bay), or each in a distinct space 32 (e.g., one sensor 16 in a fuel tank and another sensor 16 in a cargo bay). Additionally, each sensor 16 can be configured to sense a different gaseous species, as is discussed in greater detail below. Multiple sensors 16 can be connected in series or in parallel with PCM 12.

[0013] The alarm threshold of system 10 can vary depending on, for example, the gaseous species being detected. In an exemplary embodiment, sensor 16 can be configured to sense hydrogen, the lower flammability limit of which is 4% in air. In such an embodiment, system 10 can alarm when hydrogen concentrations in space 32, as sensed by sensor(s) 16, reach 1%, 2%, or somewhere therebetween (e.g., 1.5%). For non-flammable gases, a critical concentration can be used as the alarm threshold. System 10 can additionally and / or alternatively be configured to alarm based on a rate of change (i.e., rate of rise) in hydrogen concentrations in space 32 over a predetermined period of time. For example, an alarm threshold can be reached if the hydrogen concentration changes by a predetermined amount (e.g., 1%) and / or reaches a predetermined concentration (e.g., 2%) within a predetermined period of time ranging from 1 second to 300 seconds. Finally, the alarm threshold can vary depending on the type of space 32 being monitored and / or flight phase, as the presence of flammable or toxic species may not indicate an emergency situation when an aircraft is on the ground. To reduce the occurrence of false alarms caused by, for example, interference from other gases, system 10 can be configured such that two sensors 16 (e.g., hydrogen sensors) in space 32 must detect an alarmable amount of the gaseous species (e.g., 1% or 2% hydrogen) for system 10 to alarm. In some embodiments, two sensors 16 can have different sensing modalities (e.g., electrochemical and catalytic bead) while being configured to sense the same species (e.g., hydrogen). System 10 can trigger an audible and / or visual alarm in the cockpit.

[0014] For multi-gas sensing applications, system 10 can be variously configured. In one example, each sensor 16 can sense a different gaseous species, for example, with one sensor 16 sensing hydrogen and another sensor 16 sensing carbon monoxide in space 32. Alternatively, a single sensor 16 can be configured to sense and alarm for multiple gases, for example, at least two of carbon monoxide, carbon dioxide, and hydrogen sulfide (H 2 S). In either example, system 10 can be configured with different alarm thresholds and / or rates of rise for each gaseous species being detected.

[0015] The disclosed sensing systems with galvanically isolated gas sensors allow for the necessary detection of flammable and / or toxic gaseous species in aircraft spaces while minimizing the risk of combustion in these aircraft spaces from electrical current.Discussion of Possible Embodiments

[0016] The following are non-exclusive descriptions of possible embodiments of the present invention.

[0017] An aircraft sensing system includes a power and communications module, a sensor module in optical communication with the power and communications module, the sensor module being disposed in an at least partially enclosed space within the aircraft, and at least one gas sensor in communication with the sensor module, the at least one gas sensor being disposed in the at least partially enclosed space. The at least one gas sensor is configured to sense at least one flammable gas species or non-flammable gas species, and the sensor module and the at least one gas sensor are galvanically isolated from the power and communications module.

[0018] The system of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional components:

[0019] In the above system, the power and communications module can be in communication with a power source configured to supply electrical power to the power and communications module.

[0020] In any of the above systems, the power and communications module can be configured to convert the electrical power to an optical power signal.

[0021] In any of the above systems, the power and communications module can be configured to supply the optical power signal to the sensor module via a first fiber optic cable.

[0022] In any of the above systems, the power and communications module can be configured to bidirectionally communicate with the sensor module via at least one fiber optic cable.

[0023] In any of the above systems, the sensor module can include a photovoltaic power converter for converting the optical power signal to an electrical power signal to power the at least one sensor.

[0024] In any of the above systems, the sensor module can further include a signal conditioner, and an analog-to-digital converter.

[0025] In any of the above systems, the at least one flammable gas species can be at least one of hydrogen, carbon monoxide, and a hydrocarbon gas.

[0026] In any of the above systems, the at least one non-flammable gas species can be carbon dioxide.

[0027] In any of the above systems, the at least one gas sensor can be one of an electrochemical sensor, metal oxide sensor, catalytic bead sensor, and optical sensor.

[0028] In any of the above systems, the at least one gas sensor can include a first gas sensor and a second gas sensor.

[0029] In any of the above systems, the first gas sensor can be configured to sense a first flammable gas species, and the second gas sensor can be configured to sense a second flammable gas species different from the first flammable gas species.

[0030] In any of the above systems, the at least partially enclosed space can be one of a cargo bay, a fuel tank, a gas turbine engine, a cabin, and a cockpit.

[0031] In any of the above systems, the power and communications module can be located outside of the at least partially enclosed space.

[0032] In any of the above systems, the system can be configured to alarm when the at least one flammable gas species or toxic gas species reaches a threshold concentration.

[0033] In any of the above systems, the system can be configured to alarm when a concentration of the at least one flammable gas species or non-flammable gas species changes at a predetermined rate.

[0034] In any of the above systems, the sensor module can receive only optical signals from the power and communications module.

[0035] A method of monitoring a gas species on an aircraft includes sending, via a power and communications module, an optical power signal to a sensor module, powering, via the sensor module, at least one gas sensor, and sensing, via the at least one gas sensor, the gas species with an at least partially enclosed space aboard the aircraft. The gas species is a flammable gas species or a non-flammable gas species.

[0036] The method of the preceding paragraph can optionally include, additionally and / or alternatively, any one or more of the following features, configurations and / or additional steps:

[0037] The above method can further include triggering an alarm when the gas species sensed by the at least one gas sensor reaches a threshold concentration.

[0038] In any of the above methods, the gas species can be hydrogen, and the threshold concentration can be below a lower flammability limit of hydrogen.

[0039] While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An aircraft sensing system (10), comprising: a power and communications module (12); a sensor module (14) in optical communication with the power and communications module (12), the sensor module (14) being disposed in an at least partially enclosed space (32) within the aircraft; and at least one sensor (16) in communication with the sensor module (14), the at least one sensor (16) being disposed in the at least partially enclosed space (32), wherein the sensor module (14) and the at least one sensor (16) are galvanically isolated from the power and communications module (12), and characterised in that the at least one sensor (16) comprises a gas sensor, wherein the gas sensor is configured to sense at least one flammable gas species or non-flammable gas species.

2. The system (10) of claim 1, wherein the power and communications module (12) is in communication with a power source configured to supply electrical power to the power and communications module (12), and wherein the power and communications module (12) is configured to convert the electrical power to an optical power signal.

3. The system (10) of claim 2, wherein the power and communications module (12) is configured to supply the optical power signal to the sensor module (14) via a first fiber optic cable, wherein the sensor module (14) comprises a photovoltaic power converter (26) for converting the optical power signal to an electrical power signal to power the at least one sensor (16).

4. The system (10) of claim 3, wherein the power and communications module (12) is configured to bidirectionally communicate with the sensor module (16) via at least one fiber optic cable.

5. The system (10) of any preceding claim, wherein the sensor module (14) further comprises: a signal conditioner (28); and an analog-to-digital converter (30).

6. The system (10) of any preceding claim, wherein the at least one flammable gas species is at least one of hydrogen, carbon monoxide, and a hydrocarbon gas; and / or wherein the at least one non-flammable gas species is carbon dioxide.

7. The system (10) of any preceding claim, wherein the gas sensor is one of an electrochemical sensor, metal oxide sensor, catalytic bead sensor, and optical sensor.

8. The system (10) of any preceding claim, wherein the at least one sensor (16) comprises a first gas sensor and a second gas sensor.

9. The system (10) of claim 8, wherein the first gas sensor is configured to sense a first flammable gas species, and wherein the second gas sensor is configured to sense a second flammable gas species different from the first flammable gas species.

10. The system (10) of any preceding claim, wherein the at least partially enclosed space (32) is one of a cargo bay, a fuel tank, a gas turbine engine, a cabin, and a cockpit.

11. The system (10) of claim 10, wherein the power and communications module (12) is located outside of the at least partially enclosed space (32).

12. The system (10) of any preceding claim, wherein the system (10) is configured to alarm when the at least one flammable gas species or toxic gas species reaches a threshold concentration.

13. The system (10) of any preceding claim, wherein the system (10) is configured to alarm when a concentration of the at least one flammable gas species or non-flammable gas species changes at a predetermined rate and / or wherein the sensor module (14) receives only optical signals from the power and communications module (12).

14. A method of monitoring a gas species on an aircraft, the method comprising: sending, via a power and communications module (12), an optical power signal to a sensor module (14); powering, via the sensor module (14), at least one gas sensor (16); and sensing, via the at least one gas sensor (16), the gas species with an at least partially enclosed space (32) aboard the aircraft, wherein the gas species is a flammable gas species or a non-flammable gas species.

15. The method of claim 14 and further comprising, triggering an alarm when the gas species sensed by the at least one gas sensor (16) reaches a threshold concentration, wherein the gas species is hydrogen, and wherein the threshold concentration is below a lower flammability limit of hydrogen.

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