Active brake cooling using nitrogen enriched air

In some examples, a brake cooling system including a brake assembly including at least one brake pad configured to deaccelerate the vehicle during an active braking procedure, a controller configured to monitor a temperature of the at least one brake pad, an onboard inert gas generation system (OBIGGS) configured to receive air and produce a nitrogen enriched air (NEA), a NEA supply conduit connected to the OBIGGS and configured to deliver the NEA from the OBIGGS to the brake assembly, and a NEA control valve coupled to the NEA supply conduit. The controller, in response to detecting the temperature of the at least one brake pad exceeds a threshold value during the active braking procedure, operates the NEA control valve to control the flow of the NEA passing through the NEA supply conduit and delivered to the at least one brake pad.

TECHNICAL FIELD

The disclosure relates to brake pad assemblies for vehicles and mechanisms for cooling such brake pad assemblies.

BACKGROUND

Brake pads for vehicles are conventionally made using ceramic (e.g., carbon composite materials) or high strength metals (e.g., steel). During active braking procedures, the brake pads are engaged to slow the speed of the vehicle. The engagement of the brake pads produces friction between the plates causing the temperatures of the components to increase. Operating such brake pads at increased temperatures may increase the amount of wear on the brake pad thereby reducing the useful life of the brakes. In the context of aerial vehicles, once an aircraft has landed, regulation may require that the temperature of the brake pads be reduced to a nominal temperature before operation of the aircraft may be resumed.

SUMMARY

In some examples, the disclosure describes brake cooling systems for aerial vehicles that may be utilized during active braking procedures to remove heat from brake pads. In some examples the described techniques utilize nitrogen enriched air (NEA) readily available from an onboard inert gas generation system to not only cool the brake pads but also reduce the amount of oxidation that occurs on the brake pads.

In some examples, the disclosure describes a brake cooling system for a vehicle that includes a brake assembly including at least one brake pad configured to deaccelerate the vehicle during an active braking procedure, a controller configured to monitor a temperature of the at least one brake pad, an onboard inert gas generation system configured to receive air and produce a nitrogen enriched air (NEA) including at least about 90% nitrogen by volume, a NEA supply conduit connected to the onboard inert gas generation system, the NEA supply conduit configured to deliver the NEA from the onboard inert gas generation system to the brake assembly, and a NEA control valve coupled to the NEA supply conduit, the controller configured to operate the NEA control valve to control a flow of the NEA passing through the NEA supply conduit. The controller, in response to detecting the temperature of the at least one brake pad exceeds a threshold value during the active braking procedure, configured to operate the NEA control valve to control the flow of the NEA passing through the NEA supply conduit and delivered to the at least one brake pad.

In some examples, the disclosure describes a method of active brake cooling for a vehicle. The method including performing an active braking procedure on a vehicle using a brake assembly including at least one brake pad configured to deaccelerate the vehicle during the active braking procedure, detecting, by a controller of a brake cooling system, a temperature of the at least one brake pad exceeding a threshold temperature during the active braking procedure, generating a nitrogen enriched air (NEA) including at least about 90% nitrogen by volume using an onboard inert gas generation system configured to receive air and produce the NEA, and delivering the NEA to the at least one brake pad in response to detecting by the controller the at least one brake pad exceeding the threshold value. The brake cooling system includes a NEA supply conduit connected to the onboard inert gas generation system and a NEA control valve coupled to the NEA supply conduit. Delivering the NEA includes operating, by the controller, the NEA control valve to control a flow of the NEA passing through the NEA supply conduit to deliver the NEA to the at least one brake pad.

In some examples, the disclosure describes a brake cooling system for a vehicle that includes an onboard inert gas generation system configured to purify nitrogen gas in a compressed air to produce a nitrogen enriched air (NEA) including at least about 90% nitrogen by volume, a brake assembly including at least one brake pad configured to deaccelerate the vehicle during a landing procedure, at least one thermal sensor associated with the at least one brake pad, a controller configured to monitor a temperature of the at least one brake pad using the at least one thermal sensor, a NEA supply conduit connected to the onboard inert gas generation system, the NEA supply conduit configured to deliver the NEA from the onboard inert gas generation system to the brake assembly, and a variable flow NEA control valve coupled to the NEA supply conduit, the controller being configured to operate the NEA control valve to regulate a flow rate of the NEA passing through the NEA supply conduit. The controller, in response to detecting the temperature of the at least one brake pad exceeds a threshold value during the landing procedure, configured to operate the NEA control valve to regulate the flow rate of the NEA passing through the NEA supply conduit and deliver the NEA to the at least one brake pad to remove heat from the at least one brake pad.

DETAILED DESCRIPTION

This disclosure describes example techniques and systems that may be used during active braking (e.g., while the vehicle is in motion) to cool vehicle brakes and brake assemblies that are used to slow the speed of the vehicle (e.g., an aircraft). The cooling techniques and systems described below utilize an onboard inert gas generation system and a nitrogen enriched air as a cooling gas to actively cool brake components, e.g., by distributing the nitrogen enriched air over one or more brake pads. In some examples, the described systems may be used in an aerial vehicle during landing, takeoff, or taxiing procedures to maintain the relative surface temperature of one or more of the brake pads within a preset temperature range to ensure optimal performance or reduced wear of the brake pads and surrounding components of the wheel and brake assembly.

The term “cooling” or “cooling gas” is used to indicate that gas (e.g., the nitrogen enriched air) removes heat from another component (e.g., the brake pads) and does not necessarily mean that the relative temperature of the component is simultaneously decreased. In some examples depending on the rate of heat generation and the rate of heat removal by the cooling gas, the relative temperature of the component to be cooled may still increase even though the cooling gas is functioning to remove heat from the system.

FIGS. 1A and 1Bare conceptual diagrams illustrating an example brake pad cooling system10for a vehicle8that includes an onboard inert gas generation system (OBIGGS)12, also referred to as a nitrogen generation system (NGS), that receives air14(e.g., compressed air) and separates the nitrogen and oxygen content in the air to produce separate streams containing an NEA16and an oxygen enriched stream18.

OBIGGS12is onboard vehicle8meaning it is installed on vehicle8remains as a fixture of vehicle8during all operations of vehicle8, such as during flight operations, as opposed to only being connected or used with vehicle8while the vehicle is stationary. OBIGGS12may be used to actively produce a supply of NEA16onboard vehicle8during normal operations as opposed to a supply of NEA16provided via alternative means (e.g., pre-filled storage tanks having a finite supply of NEA). WhileFIG. 1Aillustrates and the accompanying description primarily describes vehicle8as aerial vehicle for ease of description, the operation of brake pad cooling system10may be incorporated into any vehicle that may benefit from the active brake cooling techniques described. Example vehicles8may include, for example, aerial vehicles fixed-wing or rotary-wing aircraft, spacecraft, or other type of flying devices; land-based vehicles such as automobiles, locomotives, military vehicles, or the like.

OBIGGS12may be connected to an air-inlet conduit20actuated by inlet control valve22, oxygen supply conduit24, and NEA supply conduit26. As described further below, NEA supply conduit26may be configured to supply NEA16to both fuel tanks28and a wheel and brake assembly30. The control of NEA16supplied to fuel tanks28and wheel and brake assembly30is actuated by control valves32and34respectfully. Brake pad cooling system10also includes controller36which may control and operate one or more aspects of brake pad cooling system10during an active braking procedure.

FIG. 2is a conceptual schematic illustration of an example OBIGGS12that may be used with brake pad cooling system10. OBIGGS12includes air-inlet conduit20feeding air14through a heat exchanger40. While air14can be from any source on board vehicle8including, for example, engine bleed air, bleed air from the aircraft's environmental control system, ram air, or air from an independent compressor, the engine bleed air provides a reliable and continuous source of compressed air that may provide a driving for the oxygen separation. In some examples, air14may contain about 21% by volume (vol. %) oxygen (O2), 78 vol. % nitrogen (N2), and traces of argon (Ar), carbon dioxide (CO2), and other gases. Depending on the flight altitude, however, air14may have a higher or lower oxygen concentration. In some examples, air14may be pressurized (e.g., compressed) between about 150 kPa and about 2200 kPa to provide sufficient driving force to promote the gas separation across gas permeable membranes44.

Heat exchanger40may receive air14and cool the air to a desirable target temperature to produce cooled compressed air42which is then fed through one or more gas permeable membranes44. The target temperature selected may depend on the type of permeable membranes44used, air flow rate, and initial pressure. In general, the permeability of gas permeable membranes44will increase as the temperature of the supply stream increases. Thus, it may preferable for exiting cooled air42to have a slightly elevated temperature. In some examples, the temperature of cooled air42may be between about 50° C. and about 100° C., for example, about 80° C. Cooled compressed air42is then fed through gas permeable membranes44, which preferentially permeates oxygen from cooled compressed air42resulting in separated oxygen enriched stream18and NEA16. In some examples, NEA16may be characterized as having a nitrogen concentration of at least 90 vol. %, for example at least about 95 vol. % nitrogen or at least about 98 vol. %. The oxygen enriched stream18may exhibit a higher oxygen content than that of air14and be used for other purposes such as an oxygen supply for vehicle8(e.g., oxygen supply for cabin/cockpit or engine operations) or the like or may be returned to the atmosphere.

Gas permeable membranes44may include any suitable membrane material designed to preferentially separate oxygen and nitrogen. Example materials may include, but are not limited to membranes comprising cellulose derivatives, polyimides, polyamide-imides, polyamides, polysulfones, copolymers and blends thereof. In some examples, membranes44may include asymmetric or composite hollow fibers. In some examples, membranes44may exhibit an oxygen permeance of at least about 10 GPU (10−6cm3/cm2·sec·cm-hg) and an oxygen to nitrogen selectivity of at least about 4.0 measured at operating conditions.

The exiting NEA16may be used as an inert gas source for filling the head space of fuel tanks28and brake pad cooling for wheel and brake assembly30. NEA16may be supplied to wheel and brake assembly30using NEA supply conduit26aconnected to OBIGGS12.

In some examples, NEA16will have a relative temperature and pressure comparable to cooled compressed air42(e.g., a temperature of about 80° C. and a pressure of about 80 psig). The flow rate of NEA16to fuel tanks28, wheel and brake assembly30, or both may be controlled by adjusting the relative flow rates through one or more of valves22,32, and34. As described further below, the flow rates of NEA16may be adjusted via controller36depending on the demand requirements for specific operations.

FIG. 3is a conceptual diagram illustrating an example wheel and brake assembly30that may be used with for brake pad cooling system10. Wheel and brake assembly30is provided for illustrative purposes and description. However, other wheel and brake assemblies may be used with for brake pad cooling system10different than those shown inFIG. 3and may include additional or fewer components, one or more brake pads, and may be arranged in different configurations, all of which are envisioned within the scope of this application.

In the example ofFIG. 3, wheel and brake assembly30includes wheel52, actuator assembly54, brake stack56, and axle58. Wheel and brake assembly30may support any variety of private, commercial, or military aircraft.

Wheel52includes wheel hub60, wheel outrigger flange62, bead seats64A and64B, lug bolt66, and lug nut68. During assembly, an inflatable tire (not shown) may be placed over wheel hub60and secured on an opposite side by wheel outrigger flange62. Actuator assembly54includes actuator housing70, actuator housing bolt72, and ram74. Actuator assembly54may include different types of actuators such as one or more of, e.g., an electrical-mechanical actuator, a hydraulic actuator, a pneumatic actuator, or the like. Brake stack56includes alternating rotor discs76aand stator discs76b; rotor discs76aare configured to move relative to stator discs76b. Rotor discs76aare mounted to wheel52, and in particular wheel hub60, by beam keys80. Stator discs76bare mounted to axle58, and in particular torque tube82, by splines84.

Actuator assembly54and parts of brake stack56may be mounted to an aircraft via torque tube82and axle58. In the example ofFIG. 3, torque tube82is affixed to axle58by a plurality of bolts86. Torque tube82supports actuator assembly54and stators76b. Axle58may be mounted on a strut of a landing gear (not shown) to connect wheel and brake assembly30to an aircraft.

Brake stack56includes alternating rotor discs76aand stator discs76b(collectively or individually “brake pads76” or “brake pad76”). Rotor discs76aare mounted to wheel hub60for common rotation by beam keys80. Stator discs76bare mounted to torque tube82by splines84. In the example ofFIG. 3, brake stack56includes four rotors and five stators. However, a different number of rotors and/or stators may be included in brake stack56in other examples. Further, the relative positions of the rotors and stators may be reversed, e.g., such that rotor discs76aare mounted to torque tube82and stator discs76bare mounted to wheel hub60.

During operation of vehicle8(e.g., aircraft), braking may be necessary from time to time, such as during landing and taxiing procedures of vehicle8. Wheel and brake assembly30is configured to provide a braking function to vehicle8via actuator assembly54and brake stack56. During operation, ram74may extend away from actuator housing70to axially compress brake stack56against compression point88for braking. Rotor discs76aand stator discs76bmay provide opposing friction surfaces for decelerating vehicle8.

As kinetic energy of a moving vehicle8is transferred into thermal energy in brake stack56, temperatures may rapidly increase in brake stack56. If left uncontrolled, the temperatures may exceed beyond 200° C. With some aircraft, emergency braking (e.g., rejected takeoff) may result in temperatures in excess of 500° C. and in some cases, even beyond 800° C. As such, rotor discs76aand stator discs76bthat form brake stack56may include robust, thermally stable materials capable of operating at such temperatures.

To handle the increased temperatures associated with vehicle8braking, rotor discs76aand/or stator discs76bmay be formed of materials such as C-C composites or high strength steel that are configured to generally withstand the high braking temperatures associated with normal aircraft braking. While such C-C composites or high strength steel brake pads are configured to withstand such high temperatures, the braking capabilities, and performance of the brake pads may diminish at excessively high temperatures. Additionally, when operated under increased temperatures, the wear on brake pads76will exponentially increase resulting in the operating life of brake pads76to be diminished.

Other hazards may also arise with increased operational temperatures associated with brake pads76. For example, as the temperatures of brake pads76increases as the result of braking, the surrounding components of wheel and brake assembly30will likewise increase in temperature. The increased temperatures of the surrounding components may lead to smoldering or damage to one or more of the components. When combined with dust or runway particulate, the elevated temperatures of wheel and brake assembly30may lead to an increased chance of fire or tire failure.

Some of the above-mentioned hazards may be mitigated with certain safe guards such as fusible plugs installed along hub60or flange62. The fusible plugs will melt at certain elevated temperature (e.g., 177° C.) to deflate the tire to avoid excessive pressure build up. However, such safeguards still cause a delay in operational turnaround of vehicle8as portions of wheel and brake assembly30will need to be replaced.

The elevated temperatures obtained during active braking may be exacerbated depending on the braking situation. For example, refused take offs (RTOs), shorten runways, reverser malfunction, increased aircraft weight (e.g., excess fuel) may all increase the demand on brake pads76thereby causing the brake pads to exceed normal operational temperatures.

In some examples, brake stack56may be cooled via air circulation (e.g., blower fans) across brake pads76activated by the pilot from the cockpit when vehicle8is stationary. Using ambient air as the cooling gas, however, introduces a relatively large concentration of oxygen across the heated surfaces of brake pads76. Such cooling gas, combined with the elevated temperatures of brake pads76, may lead to unwanted oxidative degradation of brake pads76. Furthermore, the cooling fans do not address the issue of heat buildup during active braking.

In some examples, the cooling gas may be supplied via a stored inert gas supply such as nitrogen or argon. However, such supply systems conventionally require large storage tanks that need to be periodically resupplied. Furthermore, the size and weight constraint of a stored inert gas supply make them unsuitable for including onboard an aircraft and therefore unavailable to be used active braking procedures while vehicle8is in motion.

To address one or more of the problems described above, brake pad cooling system10may be configured to deliver NEA16, using NEA supply conduit26aas a cooling gas to brake pads76during one or more active braking procedures such as during landing, takeoff, or taxiing procedures. NEA16provides a relatively inert, relatively cool (e.g., compared to temperatures that may be reached by brake pads76absent the use of cooling system10) gas to help dissipate heat generated by brake pads76. In some examples, NEA16may be used to reduce or maintain the relative surface temperature of one or more of brake pads76within a preset temperature range to ensure optimal performance or reduced wear of brake pads76and surrounding components of wheel and brake assembly30.

NEA supply conduit26amay be configured to supply NEA16to brake pads76via any suitable means. In some examples, NEA supply conduit26amay terminate with a plurality of gas nozzles90configured to distribute NEA16across one or more surfaces of brake pads76to act as a cooling gas during active braking and sedentary procedures. In some examples, NEA supply conduit26a, gas nozzles90, or both may be mounted to torque tube82or any suitable position derived from the design of wheel and brake assembly30. In some examples, nozzles90may be distributed to provide relatively uninform dispersion of NEA16over plurality of brake pads76.

In some examples, brake pad cooling system10may include one or more thermal sensors92associated with wheel and brake assembly30to monitor the temperature of one or more of brake pads76. Thermal sensors92may be actively monitored by controller36during active braking procedures to provide a real-time reading of the surface temperature of one or more of brake pads76. Based on the temperature readings provided by thermal sensors92, controller36may then operate inlet control valve22, NEA control valve34, or both to adjust the flow rate of NEA16supplied to wheel and brake assembly30to increase or decrease the amount of cooling NEA16supplied to brake pads76. In some examples, the flow rate of NEA16may be adjusted by controller36to maintain the temperature of brake pads76within a pre-programmed range. As described further below, the pre-programmed range may be adjusted based on the specific type of brake pad (e.g., C-C composite vs steel) or the manufacturer recommendations established for a specific make or model of brake pads to tailor brake cooling system10to particular types of aircrafts and wheel and brake assemblies30.

In some examples, thermal sensors92may include one or more infrared sensors, thermocouples, thermistors, resistance temperature detectors, semiconductor-based sensors, combinations thereof, or the like. Thermal sensors92may be associated with brake pads76(e.g., coupled to or adjacent to brake pads76) and used by controller36to determine the relative surface temperatures of one or more of brake pads76.

Inlet control valve22and NEA control valve34may include any suitable variable flow valve that can be coupled to and controlled by controller36to manage the flow rate of NEA16. In some examples, the flow rate of NEA16may be adjusted to provide a peak flow rate of about 5 lb/min to about 70 lb/min (about 2.3 kg/min to about 32 kg/min).

Controller36may include processing circuitry configured to monitor the temperature of one or more of brake pads76using thermal sensors92and adjust the flow rate of NEA16generated by OBIGGS12and delivered to wheel and brake assembly30by adjusting one or more of control valves22,32,34. The processing circuitry of controller36may include one or more processors, including one or more microprocessors, CPUs, CPU cores, GPUs, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), a mixed-signal integrated circuits, microcontrollers, programmable logic controllers (PLCs), programmable logic device (PLDs), complex PLDs (CPLDs), a system on a chip (SoC), any subsection of any of the above, an interconnected or distributed combination of any of the above, or any other integrated or discrete logic circuitry, or any other type of component or one or more components capable of being configured in accordance with any of the examples disclosed herein. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry.

Controller36may include one or more memory devices that include any volatile or non-volatile media, such as a RAM, ROM, non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or the like. The one or more memory devices may store computer readable instructions that, when executed by processing circuitry, cause the processing circuitry to implement the techniques attributed herein to processing circuitry for controlling operations associated with brake pad cooling system10. Thus, in some examples, controller36may include instructions and/or data stored as hardware, software, and/or firmware within the one or more memories, storage devices, and/or microprocessors.

The techniques of this disclosure may be implemented in a wide variety of computing devices. Any components, modules or units have been described to emphasize functional aspects and does not necessarily require realization by different hardware units. The techniques described herein may be implemented in hardware, software, firmware, or any combination thereof. Any features described as modules, units or components may be implemented together in an integrated logic device or separately as discrete but interoperable logic devices. In some cases, various features may be implemented as an integrated circuit device, such as an integrated circuit chip or chipset.

FIG. 4is a flow diagram illustrating an example technique of active brake cooling. For ease of illustration, the example ofFIG. 4is described as being performed via brake pad cooling system10. However, other systems suitable for carrying out the active brake pad cooling are contemplated and brake pad cooling system10may be used for additional cooling procedures than those described below.

The technique ofFIG. 4includes performing a braking procedure on a vehicle (100), detecting the temperature of at least one brake pad76for a wheel and brake assembly30exceeding a threshold temperature during the braking procedure (102), generating NEA16using OBIGGS12to covert air14into NEA16(104), deliver NEA16as a cooling gas to the at least one brake pad76(106), and optionally adjusting the flow rate of NEA16to maintain the temperature of brake pad76in a pre-programmed range (108).

As described above the braking procedure (100) may be performed on any vehicle8, such as an aerial vehicle, that includes wheel and brake assembly30. In some examples the braking procedure may include any active braking procedure in which vehicle8is in motion and utilizes the engagement of at least one brake pad76to slow the relative speed of vehicle8. Example active braking procedures may occur during, for example, aborted takeoffs, taxiing, or landing of vehicle8.

The braking procedure (e.g., landing) will cause the relative temperatures of the at least one brake pad76to increase due to the frictional engagement of the brake pad (e.g., between the adjacent brake pads76a,76b) to slow the speed of vehicle8. Using controller36, brake pad cooling system10can actively monitor the temperature of one of more of brake pads76using one or more thermal sensors92to detect when at least one of brake pads76exceed a threshold temperature (102), generating NEA using OBIGGS12(104), and delivering NEA16to at least one of brake pads76(106) to remove heat from the brake pad.

In some examples, OBIGGS12may initiate the generation of NEA16in response to the temperature of the at least one of brake pads76exceeding the threshold temperature. For example, in response to detecting the temperature of the at least one brake pad76exceeding a threshold value during the braking procedure, OBIGGS12initiates the generation of NEA, controller36may operate NEA control valve34, inlet control valve22, or both to initiate the flow of NEA16delivered to brake pads76. In other examples, OBIGGS12may be already in operation (e.g., to provide NEA16to fuel tanks28, provide a base flow of NEA16to brake pads76, or both) and controller36may then operate NEA control valve34, inlet control valve22, or both to either redirect the flow of NEA16or increase the flow of NEA16delivered to brake pads76in response to the detection of the threshold value.

The threshold temperature may be a pre-programmed temperature set based on the type of brake pad76used in wheel and brake assembly30. For example, many commercially available brake pads76have an optimal temperature range that result in a reduced wear rate.FIG. 5is a diagram illustrating a comparative spectrum of the rate of carbon wear at different indicated temperatures for three commercially available C-C brake pads from three common manufactures. As shown in theFIG. 5, the relationship between the disc temperature and wear rate of the disc is non-linear and is also different for different brake manufacturers. As one example, for Manufacturer B, the wear rate may be optimized if the temperature of brake pads76is maintained as less than about 150° C. or greater than about 315° C. In contrast, for Manufacture A, about 150° C. may represent the temperature that induces the greatest amount of wear on brake pads76. Thus, an optimal temperature range for Manufacture A may be less than about 80° C. or greater than about 250° C.

In some examples, the threshold temperature limit may be set relatively low (e.g., about 60° C.) to maintain the temperature of brake pads76within a pre-programmed temperature range (e.g., less than 150° C. for manufacture B inFIG. 5). In some examples, controller36may be configured to monitor the change in temperature of brake pads76and adjust the volumetric flow rate of NEA16(106) via one or more of control valves22and34to increase the supply of cooling gas delivered to brake pads76to maintain the temperature of the brake pads within the pre-programmed temperature range.

In some examples, controller36may be configured to supply NEA16as a cooling gas to brake pads76while the temperature of brake pads76are between a first and a second pre-programmed threshold temperature (e.g., between 50° C. and 80° C. for Manufacturer A ofFIG. 5). If brake pads76exceed the upper, second pre-programmed threshold temperature, controller36may reduce or discontinue the supply of NEA16to brake pads76to intentionally allow brake pads76to increase in temperature until they exceed a third pre-programmed threshold temperature (e.g., above 250° C. for Manufacturer A ofFIG. 5), at which point controller36may continue the supply of NEA16to keep the temperature of brake pads76between the third pre-programmed threshold temperature and a fourth pre-programmed threshold temperature (e.g., between about 250° C. and about 350° C. for Manufacturer A ofFIG. 5). By intentionally allowing brake pads76to increase in temperature over the range between the second and third threshold values, brake pad cooling system10may effectively reduce the amount of time that brake pads76operate at the temperatures that cause the maximum wear to occur. In some examples, rather than programming a series of threshold temperature values, the temperatures may be programmed based on one or more range temperatures in which brake pad cooling system10should supply NEA16as a cooling gas or reduce or discontinue the supply of NEA16to cool brake pads76.

In some examples, in addition to being supplied as a cooling gas for brake pads76during active braking procedures, NEA16may also be used to help reduce the oxidative induced wear on brake pads76during the active braking procedures. For example, thermal and catalytic oxidation of brake pads76has been a common cause of degradation for brake pads76which is accelerated by increased temperatures. NEA16may be supplied to brake pads76to create a pseudo inert environment (e.g., reduced oxygen content) thereby reducing the amount of oxidation that occurs with brake pads76. Thus, in some examples, brake pad cooling system10may supply at least a minimal or baseline amount of NEA16to brake pads76to produce a pseudo inert environment during active braking procedures regardless of the temperature of brake pads76. In some examples, the minimal or baseline amount of NEA16may have a nominal effect on cooling brake pads76.

Examples of different techniques for cooling brake pads76using NEA16have been described. In different examples, techniques of the disclosure may be implemented in different hardware, software, firmware or any combination thereof. In some examples, techniques of the disclosure may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. In some examples, techniques of the disclosure may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable storage medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.