Patent Description:
For carbon brakes, a large portion of brake wear (e.g., approximately <NUM>% of total brake wear during a life of the carbon brake) is due to braking events during taxiing with cold brakes. To limit wear, methods rely on activating only a limited number of brakes. This provides sufficient braking under normal taxi conditions. Because a limited number of brakes are activated during pedal application by the pilot, this causes a change of feel in brake response and efficacy that is noticeable to the pilot. The change in feel could cause the pilot to think that the brake system is not functioning properly. It is known from <CIT> to provide an apparatus for reducing brake wear having: a brake de-selection function for selectively disabling at least one brake on a vehicle; and a controller. The controller is configured to calculate an energy input into a brake on the vehicle during a braking event, and activate the brake de-selection function if the calculated energy input meets at least one predefined energy input criterion.

A method of taxiing an aircraft is provided as defined by claim <NUM>.

In various embodiments, modifying the brake pressure further comprises commanding a first brake pressure be supplied at a first pedal displacement to the active brake that is greater than a second pressure that is supplied at the first pedal displacement of the active brake in response to the total number of brakes being active. Modifying the brake pressure may comprise scaling the brake pressure over a predetermined range of pedal displacement based on a ratio of the total number of brakes to a total number of active brakes. The predetermined range of pedal displacement may be above an idle pedal threshold. Modifying the brake force may further comprise commanding a first brake force be supplied at a first pedal displacement to the active brake that is greater than a second force that is supplied at the first pedal displacement of the active brake in response to the total number of brakes being active. The method comprises determining a number of active brakes relative to the total number of brakes. The method may further comprise scaling the pressure (or force in the case of an electric brake) supplied to the active brake based on the number of active brakes relative to the total pressure.

An article of manufacture as defined by claim <NUM> is disclosed herein. The article of manufacture includes a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by a processor, cause the processor to perform the above method.

In various embodiments, the brake pressure supplied to the active brake as the function of pedal displacement is scaled based on a ratio of the total number of brakes to the total number of active brakes. The brake pressure may be scaled over a range of pedal displacements. The brake pressure supplied to the active brake for a first pedal displacement of a first pedal may be equal to a second brake pressure supplied to a second active brake for a second pedal displacement of a second pedal in response to the first pedal displacement being equal to the second pedal displacement. The operations may further comprise determining whether the aircraft is taxiing. Modifying the brake force may further comprise commanding a first brake force be supplied at a first pedal displacement to the active brake that is greater than a second force that is supplied at the first pedal displacement of the active brake in response to the total number of brakes being active.

A system is provided as defined by claim <NUM>.

In various embodiments, a brake control unit (BCU) is further configured to determine that the at least one of the plurality of brakes is inactive to improve wear performance. The BCU may be further configured to determine that at least two of the plurality of brakes are inactive. The brake pressure supplied to each active brake in the plurality of active brakes as the function of pedal displacement may be scaled based on a ratio of the total number of brakes to the number of active brakes. The brake pressure may be scaled over a predetermined range of pedal displacements. The operations may further comprise determining the aircraft is taxiing. The operations may further comprise reverting to a typical braking operation in response to each brake in the plurality of brakes becoming active.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration and their best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical, chemical, and mechanical changes may be made without departing from the scope of the invention as defined by the claims. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option.

As used herein, "electronic communication" means communication of electronic signals with physical coupling (e.g., "electrical communication" or "electrically coupled") or without physical coupling and via an electromagnetic field (e.g., "inductive communication" or "inductively coupled" or "inductive coupling").

In order to reduce wear of carbon brakes during a taxiing event, aircrafts may operate with fewer than a total number of available brakes. In this regard, the carbon brakes may heat up more quickly and wear fewer due to the increased heat. With the reduction active brakes being utilized, a pilot may think that the brake system is not acting properly and react accordingly. Thus, the systems and methods disclosed herein are configured to provide a pilot with a similar feel to normal braking operations when operating with fewer brakes than the total number of active brakes, in accordance with various embodiments.

In various embodiments, and with reference to <FIG>, a front view of an aircraft <NUM> on a runway <NUM> is depicted. Aircraft <NUM> may include landing gear such as a left main landing gear (LMLG) <NUM>, a right main landing gear (RMLG) <NUM>, and a nose landing gear (NLG) <NUM>. LMLG <NUM>, RMLG <NUM>, and NLG <NUM> may generally support aircraft <NUM> when aircraft <NUM> is not flying, allowing aircraft <NUM> to taxi, take off and land without damage. LMLG <NUM> may include an outboard wheel 13A and an inboard wheel 13B coupled by a strut <NUM>; RMLG <NUM> may include an outboard wheel 15A and an inboard wheel 15B coupled by a strut <NUM>; and NLG <NUM> may include a nose wheel 17A and a nose wheel 17B coupled by a strut <NUM>. The nose wheels differ from the main wheels in that the nose wheels may not include a brake, in accordance with various embodiments. In various embodiments, aircraft <NUM> may comprise any number of landing gears and each landing gear may comprise any number of wheels.

Aircraft <NUM> may also include a primary braking system <NUM>, which may be applied to any wheel of any landing gear. Braking system <NUM> of aircraft <NUM> may comprise a collection of subsystems that produce output signals for controlling the braking force and/or torque applied at each wheel (e.g., outboard wheel 13A, inboard wheel 13B, outboard wheel 15A, inboard wheel 15B, nose wheel 17A, and/or nose wheel 17B), together with various brakes, as discussed further herein. Braking system <NUM> may communicate with the brakes of each landing gear (e.g., LMLG <NUM>, RMLG <NUM>, and/or NLG <NUM>), and each brake may be mounted to each wheel to apply and release braking force on one or more wheels (e.g., as described herein).

Aircraft wheel and brake assemblies may typically include a non-rotatable wheel support, a wheel mounted to the wheel support for rotation, and a brake disk stack. The brake stack may also have alternating rotor and stator disks mounted with respect to the wheel support and wheel for relative axial movement. Each rotor disk may be coupled to the wheel for rotation therewith, and each stator disk may be coupled to the wheel support against rotation. A back plate may be located at the rear end of the disk stack and a brake head may be located at the front end. The brake head may house one or more actuator rams that extend to compress the brake disk stack against the back plate, or the brake disk stack may be compressed by other means. Torque is taken out by the stator disks through a static torque tube or the like. The actuator rams may be electrically operated actuator rams or hydraulically operated actuator rams, although some brakes may use pneumatically operated actuator rams.

In brake systems that employ fluid powered (hydraulic or pneumatic power) actuator rams, the actuator ram may be coupled to a power source via a brake servo valve (BSV) and a shutoff valve (SOV). The SOV effectively functions as a shutoff valve, wherein in a first position (e.g., an armed position), fluid pressure is permitted to pass through the valve, while in a second position (e.g., a disarmed position) fluid pressure is restricted or prevented from passing through the valve. During normal braking, the SOV is in the armed position, thereby permitting the flow of fluid pressure. The BSV, based on braking commands from the pilot (often via an electronic controller that may implement, for example, brake selection logic) controls the amount of fluid pressure provided to the actuator ram, and thus, the braking force applied to the wheel.

In electric brakes, a brake controller (or controller) is coupled to one or more electromechanical actuator controllers (EMAC) for a brake, which drives one or more electromechanical brake actuators. The brake controller may be in communication with a brake pedal, and thus may control the EMAC in accordance with pilot/copilot braking commands. In various aircraft, other means are used to compress a brake disk stack. A brake controller may comprise a processor and a tangible, non-transitory memory. The brake controller may comprise one or more logic modules that implement brake logic. In various embodiments, the brake controller may comprise other electrical devices to implement brake logic.

In various embodiments, and with reference to <FIG>, an aircraft braking system <NUM> is disclosed. Aircraft braking system <NUM> may be configured to select a number of brakes to be utilized for an aircraft (e.g., aircraft <NUM> of <FIG>) during a taxiing phase and, in response to selecting the number of brakes, modify a pressure supplied to the brakes relative to a pedal deflection during the taxiing. In that respect, aircraft braking system <NUM> may control brake selection, for example, whether an outboard brake or and inboard brake is used for taxiing, and modify a pressure supplied to the selected brakes in response to the brake selection, in accordance with various embodiments. Aircraft braking system <NUM> may be configured to select between exclusive use of an inboard or outboard brake prior to a taxi event, select any number of brakes for use during a taxi event or the like. For example, an inboard brake of a landing gear assembly may be chosen prior to an aircraft taxiing based on having less wear than an outboard brake of the landing gear assembly. During taxi, the aircraft braking system <NUM> can modify a pressure supplied to each brake based on the number of brakes selected previously. In this regard, a feel for a pilot of an aircraft (e.g., aircraft <NUM> from <FIG>) may remain constant regardless of a number of brakes used, in accordance with various embodiments.

Furthermore, aircraft braking system <NUM> may be used to control, for example, four or more aircraft wheels (e.g., outboard wheel 13A, inboard wheel 13B, outboard wheel 15A, inboard wheel 15B, of <FIG>). Aircraft braking system <NUM> may be configured to select a single wheel from LMLG <NUM> and a single wheel from RMLG <NUM> for use during taxiing to maintain differential braking. Any number and configuration of wheels controlled by aircraft braking system <NUM> is within the scope of the present disclosure, as described further herein.

In various embodiments, aircraft braking system <NUM> may also be integrated into computer systems onboard an aircraft (e.g., aircraft <NUM> of <FIG>) such as, for example, a brake control unit (BCU), a full authority digital engine control (FADEC), an engine-indicating and crew-alerting system (EICAS), and/or the like. Aircraft braking system <NUM> may also be a standalone computer system separate from the aircraft and in electronic communication with the aircraft, as described in further detail herein. Aircraft braking system <NUM> may include one or more processors and/or one or more tangible, non-transitory memories and be capable of implementing logic. As described herein, each "controller", and/or the like may also comprise an individual processor and/or one or more tangible, non-transitory memories and be capable of implementing logic. In various embodiments, each controller, and/or the like may also be implemented in a single processor (e.g., aircraft braking system <NUM> may comprise a single processor). Each processor can be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof.

In various embodiments, aircraft braking system <NUM> may comprise a processor <NUM> configured to implement various logical operations in response to execution of instructions, for example, instructions stored on a non-transitory, tangible, computer-readable medium. As used herein, the term "non-transitory" is to be understood to remove only propagating transitory signals per se from the claim scope and does not relinquish rights to all standard computer-readable media that are not only propagating transitory signals per se.

In various embodiments, aircraft braking system <NUM> may comprise a brake control unit (BCU) <NUM> in operative communication with a plurality of servo valves <NUM>. A number of servo valves in the plurality of servo valves <NUM> corresponds to a number of brakes for the aircraft braking system <NUM>. For example, <FIG> illustrates an aircraft braking system <NUM> with four servo valves corresponding to four brakes (a left outboard servo valve <NUM>, a left inboard servo valve <NUM>, a right inboard servo valve <NUM>, and a right outboard servo valve <NUM>. However, the present disclosure is not limited in this regard and any number servo valve / brake combinations is within the scope of this disclosure.

In various embodiments, and with brief reference to <FIG>, LMLG <NUM> and RMLG <NUM> may each comprise two or more wheels. For example, LMLG <NUM> may comprise an axle comprising a left outboard brake with the left outboard servo valve <NUM> and a left inboard brake with the left inboard servo valve <NUM>. Similarly, RMLG <NUM> may comprise an axle comprising a right inboard brake with the right inboard servo valve <NUM> and a right outboard brake with the right outboard servo valve <NUM>. The BCU <NUM> may be electronically coupled to the plurality of servo valves <NUM>.

In various embodiments, BCU <NUM> may comprise various components to aid in selecting an inboard or outboard brake for a respective landing gear and determining a brake pressure to supply to each servo valve in the selected servo valves relative to a pedal displacement based on the number of selected brakes. For example, BCU <NUM> may comprise a computing device (e.g., processor <NUM>) and an associated memory <NUM>. Processor <NUM> may comprise any suitable processor, such as, for example, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. Memory <NUM> may comprise an article of manufacture including a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by the computing device (e.g., processor <NUM>), cause the computing device to perform various methods, as discussed further herein.

In various embodiments, each servo valve in the plurality of servo valves <NUM> controls the amount of fluid pressure provided to the actuator ram, and thus, the braking force applied to the wheel of the respective servo valve as described further herein.

In various embodiments, the methods and systems disclosed herein are not limited to fluid powered brake systems. For example, with reference now to <FIG>, an aircraft braking system <NUM> with electronic brakes is illustrated, in accordance with various embodiments. For example, the aircraft braking system may comprise a plurality of electromechanical brake actuators <NUM>. Although illustrated as being directly controlled by the BCU <NUM>, each electromechanical brake actuator (e.g., left outboard electromechanical brake actuator <NUM>, left inboard electromechanical brake actuator <NUM>, right inboard electromechanical brake actuator <NUM>, and right outboard electromechanical brake actuator <NUM>) may be controlled locally by an EMAC in electronic communication with the BCU <NUM>. The present disclosure is not limited in this regard.

Referring now to <FIG>, a plot of brake pressure as a function of pedal response for a braking system with all brakes active (plot <NUM>) compared to a braking system with half of the brakes active (plot <NUM>) is illustrated, in accordance with various embodiments. In order to maintain a similar pedal feel for a respective pilot during taxiing and while a brake wear reduction method is active, as discussed previously herein, a pressure supplied to a respective brake per percent of pedal deflection is modified based on a number of brakes active. For example, if only two brakes are used (e.g., a left inboard brake with left inboard servo valve <NUM> from <FIG> or a left inboard electromechanical brake actuator <NUM> from <FIG> and a right inboard brake with a right inboard servo valve <NUM> from <FIG> or a right inboard brake with a right inboard electromechanical brake actuator <NUM>) out of a total of four potential brakes being active, a pressure or force curve (i.e., force supplied by active electromechanical brake actuators in the case of electric brakes) may be scaled by a factor of <NUM> for a range of pedal displacement (e.g., from <NUM>% to <NUM>% pedal displacement), in accordance with various embodiments. An initial range of pedal displacement (e.g., between <NUM>% and <NUM>%) may remain approximately <NUM> and an end range of pedal displacement (e.g., from <NUM>% to <NUM>%) may converge to a maximum supply pressure or maximum force. The initial range of pedal displacement may end at an "idle pressure or force threshold", or a minimum pedal displacement for which brake pressure begins to be supplied or brake force begins to be applied. The level of scaling at an end of the pressure or force curve may be sufficient in many applications because typically if a pilot presses a pedal above a threshold pedal displacement (e.g., <NUM>% pedal displacement), a pilot often intends to apply full braking capability (e.g., approximately maximum pressure or maximum force). In various embodiments, force curves as disclosed herein would look similar to the pressure curves shown in <FIG> with force on the Y-axis as opposed to pressure.

Referring now to <FIG>, a plot of brake pressure as a function of pedal response for a braking system with all brakes active and eight total brakes (plot <NUM>) compared to a braking system with only three brakes on each side (six total brakes) active (plot <NUM>) is illustrated, in accordance with various embodiments. If only six of eight brakes are active, then the pedal pressure curve (e.g., plot <NUM>) is scaled by a factor of eight over six, or approximately <NUM>. In this regard, a similar pedal feel for a respective pilot will be experienced during taxiing while only the six of eight brakes are active for a range of pedal displacement (e.g., between <NUM>% and <NUM>%), in accordance with various embodiments.

Although scaling in accordance with <FIG> and <FIG> is likely sufficient for a majority of applications, the method and systems disclosed herein may be further refined. For example, with reference now to <FIG> and <FIG>, a further refined version of a braking system from <FIG> (<FIG>) and a further refined version of a braking system from <FIG> (<FIG>) are illustrated, in accordance with various embodiments. As illustrated in <FIG> and <FIG>, scaling a supply pressure may be applied relative to pedal displacement until a maximum supply pressure is reached. Once the maximum supply pressure is reached, the supply pressure will remain constant (i.e., at the maximum supply pressure) until <NUM>% pedal deflection is achieved.

Referring now to <FIG>, a process <NUM> for performing a feel adjustment braking method (e.g., via a BCU <NUM> from <FIG> or BCU <NUM> from <FIG>) is illustrated, in accordance with various embodiments. The process starts in start block <NUM> and proceeds to determine, via a processor, whether the aircraft is taxiing (step <NUM>). For example, the BCU <NUM>, <NUM> may make this determination in response to receiving an aircraft speed from a speed sensor or the like and comparing the aircraft speed to a predetermined threshold. For example, the BCU <NUM>, <NUM> may determine the aircraft is taxiing in response to an aircraft speed being between <NUM> knots and <NUM> knots, or between <NUM> knots and <NUM> knots, in accordance with various embodiments. In various embodiments, the BCU <NUM>, <NUM> may determine the aircraft <NUM> from <FIG> is on the ground in response to receiving an indication that landing gear both have a weight on wheels from weight on wheel sensors in communication with the BCU <NUM>, <NUM>. If the process <NUM> determines the aircraft is taxiing, the process proceeds to step <NUM>. If the process <NUM> determines the aircraft is not taxiing, the process ends at step <NUM>.

The process <NUM> further comprises determining whether a brake wear optimization mode is active (step <NUM>). A "brake wear optimization mode" as referred to herein is any brake configuration where a number of brakes active during a taxiing event is fewer than the total number of brakes that could be active for the taxiing event. If the process <NUM> determines the aircraft is in a brake wear optimization mode, the process proceeds to step <NUM>. If the process determines the aircraft is not in the brake wear optimization mode, the process ends at step <NUM> and proceeds to supply normal typical pressure as a function of pedal displacement.

The process <NUM> further comprises scaling a pedal pressure curve (e.g., <FIG>) based on a number of brakes active relative to the total number of brakes (step <NUM>). Thus, in various embodiments, the systems and methods disclosed herein, for the same pedal displacement, regardless of taxi brake mode, allow a pilot to have feel a similar amount of brake force on a gear of a pedal since a torque provided by the brakes is roughly proportional to brake pressure. Although fewer brakes are active, more pressure is applied to active brakes providing an equivalent amount of torque on a LMLG <NUM> and RMLG <NUM> from <FIG>. Thus, pilots may experience a response feel that they are used to when all brakes are operational, in accordance with various embodiments.

In various embodiments, the pilot does not compensate with extra pedal deflection to get an expected deceleration of an aircraft for a given pedal deflection in response to being in a brake wear optimization mode. In this regard, the systems and methods disclosed herein provide a consistent feel of the brake system to the pilot and avoid a concern a pilot may have that the brake system is not reacting as expected.

Claim 1:
A method of taxiing an aircraft, the method comprising:
determining (<NUM>), via a controller (<NUM>), whether the aircraft is taxiing with fewer brakes active than a total number of brakes;
determining a number of active brakes relative to the total number of brakes;
modifying, via the controller, one of a brake pressure or a brake force supplied to an active brake of the aircraft as a function of pedal deflection in response to determining the aircraft is taxiing with fewer brakes active relative to the total number of brakes, wherein modifying the brake pressure or brake force comprises scaling (<NUM>) the brake pressure or brake force over a predetermined range of pedal displacement based on a ratio of the total number of brakes to the total number of active brakes, and one of:
converging an end range of pedal displacement to one of a maximum supply pressure or maximum brake force, or
once the maximum supply pressure or the maximum brake force is reached,
the supply pressure or the brake force remains constant until <NUM>% pedal deflection is achieved.