Patent Description:
Some aircraft include one or more landing gear having brake systems disposed therein. Aircraft multi-disk brake systems typically employ a series of friction disks (rotors and stators) forced into contact with each other to stop the aircraft. The braking system can generate relatively large amounts of heat due to the relatively large mass of the aircraft and due to the relatively high velocity of the aircraft upon landing. The friction disks may experience wear during braking events. <CIT> relates to a combined drive and brake mechanism with a rotor comprising a set of vanes located in a cavity of an axle housing, where the cavity is configured to be pressurized via an electrically operated valve, which impedes a free rotation of the rotor. <CIT> relates to a wheel brake. <CIT> relates to a brake system.

<CIT> relates to a power translation mechanism.

A hydraulic brake system for use in an aircraft landing gear is provided in claim <NUM>.

A hybrid brake system for use in an aircraft landing gear is provided in claim <NUM>.

A method of using a braking system is provided in claim <NUM>.

The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present invention, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.

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 invention, 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 in the appended 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.

Referring now to <FIG>, an aircraft <NUM> in accordance with various embodiments can include multiple landing gear including main landing gear <NUM>, nose landing gear <NUM> and main landing gear <NUM>. Each landing gear may include one or more wheel assemblies. For example, the landing gear <NUM> includes an inner wheel assembly <NUM> and an outer wheel assembly <NUM>. The inner wheel assembly <NUM> and the outer wheel assembly <NUM>, along with the other wheels of the aircraft <NUM>, can include a braking system that provides a braking force to the corresponding wheel. Each braking system may comprise a hydraulic braking system or a hybrid hydraulic brake system, as disclosed further herein.

Referring now to <FIG>, a cross-sectional view of a brake system <NUM>, in accordance with various embodiments, is illustrated. In various embodiments, the brake system <NUM> may comprise a hybrid braking system (i.e., a mechanical brake system and a hydraulic brake system), a hydraulic brake system only, or the like. The brake system <NUM> comprises a first wheel <NUM> and an axle assembly <NUM>. The first wheel is coupled to the axle assembly <NUM> and configured to rotate about a centerline A-A' of axle assembly <NUM>. The brake system <NUM> may further comprise a second wheel <NUM> disposed opposite the first wheel <NUM>. The second wheel <NUM> may be coupled to the first wheel <NUM> via the axle assembly <NUM>. In various embodiments, first wheel <NUM> and second wheel <NUM> may be configured for differential braking, or the like. Although illustrated as having a first wheel <NUM>, and a second wheel <NUM>, any number of wheels for landing gear is within the scope of this invention.

In various embodiments, the axle assembly <NUM> comprises a first outer axle <NUM> and an inner axle <NUM>. The first outer axle <NUM> may be disposed between inner axle <NUM> and first wheel <NUM>. The axle assembly <NUM> may further comprise a second outer axle <NUM>. The second outer axle <NUM> may be disposed between inner axle <NUM> and the second wheel <NUM>. The inner axle <NUM> may be supported by a first support bearing <NUM> disposed at a first end of inner axle <NUM> proximate the first outer axle <NUM> and a second support bearing <NUM> disposed at a second end of inner axle <NUM> proximate the second outer axle <NUM>. The first outer axle <NUM> may be supported by a first impact bearing <NUM> and the second outer axle <NUM> may be supported by a second impact bearing <NUM>.

In various embodiments, the brake system <NUM> further comprises an inner axle housing <NUM> and a frame <NUM>. The inner axle housing <NUM> may fully enclose the inner axle <NUM>. The inner axle housing <NUM> may be coupled to the frame <NUM> and/or supported structurally by the frame <NUM>. In various embodiments, frame <NUM> is coupled to a landing gear strut <NUM>. Landing gear strut <NUM> may be a part of a main landing gear strut, such as main landing gear <NUM> and/or main landing gear <NUM> from <FIG>.

In various embodiments, the inner axle housing <NUM> may comprises a first aperture <NUM> disposed proximate the first wheel <NUM> and a second aperture <NUM> disposed proximate the second wheel <NUM>. The axle assembly <NUM> may extend from the first wheel <NUM> through the first aperture <NUM> and the second aperture <NUM> to the second wheel <NUM>. The first support bearing <NUM> may be disposed in the first aperture <NUM>. The second support bearing <NUM> may be disposed in the second aperture <NUM>. The inner axle housing <NUM> may further comprise a first axle seal <NUM> disposed adjacent to the first aperture <NUM> and a second axle seal <NUM> disposed adjacent to the second aperture. The first axle seal <NUM> and the second axle seal <NUM> may be configured to fluidly isolate an internal cavity of the inner axle housing <NUM> from an internal cavity of the frame <NUM>.

In various embodiments, a working fluid <NUM> is disposed within the inner axle housing <NUM>. The working fluid may be any fluid known in the art, such as a noncorrosive/lubricating and/or non-compressible fluid (e.g., hydraulic fluid, engine oil, machine oil, gear oil, or the like).

In various embodiments, the inner axle <NUM> comprises a plurality of paddles <NUM> disposed axially along the inner axle <NUM> and extending radially outward from the inner axle <NUM>. During operation, the plurality of paddles <NUM> rotate with the axle assembly <NUM> and the wheels <NUM>, <NUM>. The working fluid <NUM> may be configured to provide hydraulic friction to the plurality of paddles <NUM> and/or slow down the plurality of paddles and the wheels <NUM>, <NUM>. In various embodiments, a portion of the working fluid <NUM> may be disposed in the inner axle housing <NUM> and a portion of the working fluid may be disposed in a tank external to the inner axle housing <NUM>. A pressure differential between the tank and the inner axle housing <NUM> may occur during operation of the brake system <NUM>.

In various embodiments, the brake system <NUM> may further comprise a heat exchanger <NUM> and a throttling valve <NUM>. The heat exchanger <NUM> may be disposed in a strut of a main landing gear assembly (e.g., landing gear strut <NUM>). The heat exchanger <NUM> may be in fluid communication with the internal cavity of the inner axle housing <NUM> through the frame <NUM>. The throttling valve <NUM> may be configured to modulate a throttling pressure to the working fluid <NUM>, the throttling pressure may increase during use and the increased pressure may impede the free rotation of the plurality of paddles <NUM>. In this regard, a braking motion of the wheels <NUM>, <NUM> occurs from the increased pressure. In various embodiments, the heat exchanger <NUM> may comprise an air-oil cooler, cross-flow heat exchanger, or the like.

The brake system <NUM> may further comprise a multi-disk braking assembly <NUM>. The multi-disk braking assembly <NUM> may comprise a plurality of rotors <NUM>, a plurality of stators <NUM>, and a plurality of pistons <NUM>. The plurality of rotors <NUM> may be interleaved with the plurality of stators <NUM> within frame <NUM>. The plurality of rotors <NUM> may extend radially outwards from the first outer axle <NUM> and/or the second outer axle <NUM>. The plurality of stators <NUM> may extend radially inward from the frame <NUM>. The plurality of pistons may be disposed proximate first wheel <NUM> and/or proximate second wheel <NUM>. The plurality of pistons <NUM> may be configured to extend axially inward toward the plurality of rotors <NUM> and the plurality of stators <NUM>. In this regard, the plurality of rotors <NUM> may contact the plurality of stators <NUM> and/or provide redundant braking. The multi-disk braking assembly <NUM> may be utilized to achieve a heavier braking force, or when any other braking device, such as a aerodynamic spoiler or thrust reverser is malfunctioning. Although the brake system <NUM> is illustrated with redundant braking, a hydraulic braking system without the multi-disk braking assembly <NUM> is within the scope of this invention.

Referring now to <FIG>, a cross-sectional view of the brake system <NUM> along section line B-B from <FIG>, in accordance with various embodiments, is illustrated. In various embodiments, the plurality of paddles <NUM> may be disposed circumferentially about inner axle <NUM>. For example, a first paddle <NUM> in the plurality of paddles <NUM> may be disposed circumferentially adjacent to a second paddle <NUM> and a third paddle <NUM>. In various embodiments, there may be any number of paddles in the plurality of paddles <NUM> disposed circumferentially at a given axial location. For example, there may be between <NUM> and <NUM> paddles at a given axial location, or between <NUM> and <NUM> paddles, or about <NUM> paddles.

Referring now to <FIG>, a perspective cross-sectional view of a brake system <NUM>, in accordance with various embodiments, is illustrated. In various embodiments, the frame <NUM> may be annular in shape. Although illustrated as annular in shape, the frame <NUM> may be any shape known in the art.

In various embodiments, the plurality of rotors <NUM> may comprise a first plurality of rotors <NUM> and a second plurality of rotors <NUM>. The first plurality of rotors <NUM> may extend radially outward from the first outer axle <NUM>. The second plurality of rotors <NUM> may extend radially outward from the second outer axle <NUM>.

In various embodiments, the plurality of stators <NUM> may comprise a first plurality of stators <NUM> and a second plurality of stators <NUM>. The first plurality of stators <NUM> may be interleaved between the first plurality of rotors <NUM>. The second plurality of stators <NUM> may be interleaved between the second plurality of rotors <NUM>.

In various embodiments, the plurality of pistons <NUM> may comprise a first plurality pistons <NUM> and a second plurality of pistons <NUM>. The first plurality of pistons <NUM> may be moveably coupled to a first end of the frame <NUM>. The first end of the frame <NUM> may be proximate the first wheel <NUM>. The first plurality of pistons <NUM> may be disposed circumferentially about an axial wall <NUM> of the frame <NUM>. For example, a first piston <NUM> in the first plurality of pistons <NUM> and a second piston <NUM> in the plurality of pistons <NUM> may be disposed approximately <NUM> degrees apart. In various embodiments, there may be any number of pistons in the first plurality of pistons <NUM>. The second plurality of pistons <NUM> may be in accordance with the first plurality of pistons <NUM> but disposed proximate the second wheel <NUM> on a second end of the frame <NUM>.

Referring now to <FIG>, a method <NUM> of using a braking system, in accordance with various embodiments, is illustrated. With combined reference to <FIG> and <FIG>, the method <NUM> may comprise applying a modulated hydraulic pressure to a hydraulic fluid surrounding an inner axle (step <NUM>). The modulated hydraulic pressure may be applied by a throttling valve <NUM>, or the like. The hydraulic fluid may be disposed in an inner axle housing <NUM> of a main landing gear assembly. The inner axle may be in accordance with inner axle <NUM> and comprise a plurality of paddles <NUM> disposed axially along the inner axle <NUM> and extending radially outward from the inner axle <NUM>.

The method <NUM> may further comprise inducing a pressure differential in a cavity of the inner axle housing (step <NUM>). The pressure differential may be between a tank and the inner axle housing (e.g., inner axle housing <NUM>). The method <NUM> may further comprise impeding a free rotation of a plurality of paddles in response to an increased pressure from the pressure differential (step <NUM>). The plurality of paddles may be in accordance with the plurality of paddles <NUM> and extend radially outward from the inner axle <NUM> and be disposed axially along the inner axle <NUM> and circumferentially about inner axle <NUM>. Due to an increased friction between the plurality of paddles and the hydraulic fluid, a braking motion may be experienced by the wheels (e.g., wheels <NUM>, <NUM>).

The method <NUM> may further comprise measuring a wheel speed (step <NUM>). A wheel speed may be measured by a speed sensor disposed in the main landing gear, or the like. The wheel speed may be communicated to an electronic control unit (ECU), or the like. The method <NUM> may further comprise varying the modulated hydraulic pressure in response to the measured wheel speed (step <NUM>). By varying the modulated hydraulic pressure, the system may prevent any wheel lock-up, or the like.

The method <NUM> may further comprise circulating the hydraulic fluid through a heat exchanger (step <NUM>). The heat exchanger may be in accordance with heat exchanger <NUM>. The hydraulic fluid may be kept below a flash point by circulating the hydraulic fluid through the heat exchanger. In this regard, the heat exchanger may maintain a temperature of the hydraulic fluid that is less than a flash point of the hydraulic fluid during operation of the braking system.

However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions. The scope of the invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more.

In the detailed description herein, references to "one embodiment", "an embodiment", "an example embodiment", etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the invention in alternative embodiments.

Claim 1:
A hydraulic brake system for use in an aircraft landing gear,
the hydraulic brake system comprising:
a throttling valve (<NUM>);
an inner axle housing (<NUM>) defining a first cavity, the throttling valve fluidly coupled to the first cavity of the inner axle housing (<NUM>);
an inner axle (<NUM>) disposed in the inner axle housing, the inner axle comprising a plurality of paddles (<NUM>) extending radially outward from the inner axle;
a first outer axle (<NUM>) coupled to a first axial end of the inner axle and a second outer axle (<NUM>) coupled to a second axial end of the inner axle, the first and second outer axles disposed external to the inner axle housing (<NUM>), wherein:
the first cavity is configured to be pressurized via the throttling valve (<NUM>) and impede a free rotation of the inner axle (<NUM>);
the plurality of paddles (<NUM>) includes a first set of paddles spaced apart circumferentially about the inner axle (<NUM>), a second set of paddles spaced apart
circumferentially about the inner axle (<NUM>), and a third set of paddles spaced apart circumferentially about the inner axle (<NUM>);
the first set of paddles spaced apart axially from the third set of paddles; and
the second set of paddles spaced apart axially, and disposed axially between, the first set of paddles and the third set of paddles.