Patent Description:
Traditional methods of nosewheel steering tend to be relatively complex and may be unreliable due to such complexity. <CIT> describes a landing gear steering apparatus including a rotary tube mounted to rotate inside a strut about an axis of rotation of the rotary tube, a sliding rod mounted to slide inside the rotary tube for supporting the wheels of the landing gear and connected to the rotary tube via a scissor linkage, and a body fixed to the strut. A crank is mounted inside the body, and has a bottom end carrying a gear wheel meshing with a toothed ring fixed to the rotary tube. Other landing gear steering apparatus are known from <CIT> and <CIT>.

In various embodiments, systems, methods, and articles of manufacture (collectively, the "system") for nosewheel steering are disclosed. A steering apparatus is provided in claim <NUM> and comprises a steering collar for coupling to an aircraft landing gear strut cylinder and including a sidewall and a portal through the sidewall, a first linear actuator, a first drive gear, a crankshaft, and a sun gear, wherein the sun gear is disposed within the steering collar, wherein the first drive gear is fixed to the crankshaft and coupled to the sun gear via the portal such that the steering collar rotates about the sun gear in response to rotation of the crankshaft, wherein the first linear actuator is coupled between the crankshaft and the steering collar.

In various embodiments, the apparatus may comprise a second drive gear fixed to the crankshaft. In various embodiments, a second linear actuator may be coupled between the crankshaft and the steering collar. In various embodiments, the second linear actuator may be arranged with the first linear actuator in a V configuration. In various embodiments, the second linear actuator may be arranged with the first linear actuator in an in-line configuration.

A steering system for an aircraft comprises a strut cylinder, a strut piston, and a steering apparatus as described above, wherein the steering collar is coupled to the strut cylinder, and wherein the sun gear is fixed to the strut cylinder.

In various embodiments, the system comprises a second drive gear fixed to the crankshaft. In various embodiments, the system comprises a second linear actuator coupled between the crankshaft and the steering collar. In various embodiments, the second linear actuator is arranged with the first linear actuator in a V configuration. In various embodiments, the second linear actuator is arranged with the first linear actuator in an in-line configuration. In various embodiments, the steering collar further comprises a retention feature opposite an upper surface of the steering collar and configured to retain the sun gear within the steering collar. In various embodiments, the steering collar includes a reinforced portion at the upper surface, wherein the reinforced portion abuts a shoulder of the strut cylinder generating a contact therebetween which inhibits the steering collar from translating axially upward along the strut cylinder.

In various embodiments, an aircraft comprises a plurality of landing gear and a steering system as described above, coupled to at least one of the plurality of landing gear, the steering system comprising a strut cylinder, a strut piston, and a torque link coupled to the steering collar.

The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise, to the extent that they fall within the scope of the claims.

A more complete understanding of the present disclosure, however, may 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 disclosures, 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 disclosures. 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.

In various embodiments, and with reference to <FIG>, an aircraft <NUM> in accordance with various embodiments may comprise aircraft systems, for example, one or more landing gear such as landing gear <NUM>, landing gear <NUM> and landing gear <NUM>. Landing gear <NUM>, landing gear <NUM> and landing gear <NUM> may generally support aircraft <NUM> when aircraft <NUM> is not flying, allowing aircraft <NUM> to taxi, take off, and land without damage and may comprise wheels and an oleo strut, also referred to as a shock strut, comprising a strut cylinder and a strut piston filled with a hydraulic fluid. For example, landing gear <NUM> may include wheels <NUM> coupled by an axle <NUM> and a shock strut assembly <NUM>. In various embodiments, one or more landing gear such as, for example, the landing gear <NUM> may comprise a steering system <NUM> configured to enable the axle to pivot about the axis of the shock strut assembly. In this regard, the steering system <NUM> may tend to enhance the maneuverability of the aircraft <NUM> when operating on the ground.

In various embodiments, and with reference to <FIG>, steering system <NUM> is illustrated in accordance with various embodiments. The steering system <NUM> may be mounted on a forward most landing gear of aircraft <NUM> (i.e., proximate the nose and thus referred to as nosewheel), in this regard, tend to enable the aircraft <NUM> to turn. The steering system <NUM> includes a steering collar <NUM> (i.e., collar), a crankshaft <NUM>, a first drive gear <NUM>, and an linear actuator <NUM>. The steering collar <NUM> is mounted to a strut cylinder <NUM> of the landing gear <NUM>. In various embodiments, a first bearing mount <NUM> and a second bearing mount <NUM> extend orthogonally from the outermost diameter of the steering collar <NUM>. The crankshaft <NUM> may be coupled between the bearing mounts (<NUM>, <NUM>) and parallel to the axis of the strut cylinder <NUM>. In this regard, the crankshaft <NUM> may be free to rotate. The first drive gear <NUM> is fixed to the crankshaft <NUM>. In various embodiments, a second drive gear <NUM> may be fixed to the crankshaft <NUM>.

In various embodiments, the linear actuator <NUM> is coupled between the crankshaft <NUM> and the steering collar <NUM>. In this regard, the linear actuator <NUM> may be configured to drive the rotation of the drive gears (<NUM>, <NUM>) via the crankshaft <NUM>. For example, a first end <NUM> of the linear actuator <NUM> may be coupled to a crank pin <NUM> (shown in <FIG>) of the crankshaft <NUM>. A second end <NUM> of the linear actuator <NUM> may include a trunnion <NUM>. The trunnion <NUM> may be coupled to a trunnion block <NUM> of the steering collar <NUM>. In various embodiments, the trunnion <NUM> may be coupled to the linear actuator <NUM> via a trunnion arm <NUM>. The trunnion arm <NUM> may tend to provide improved clearance between the steering collar <NUM> and align the first end <NUM> with the crank pin.

In various embodiments and with additional reference to <FIG>, steering system <NUM> is shown in cross section to a plane orthogonal to the strut cylinder <NUM>. Linear actuator <NUM> is illustrated as a piston-type linear actuator but it will be appreciated that any type (e.g., hydraulic, pneumatic, electrical, etc.) of linear actuator may be employed. In response to a command signal, the linear actuator <NUM> may cause rotation of the crankshaft <NUM> and thereby the drive gears (<NUM>, <NUM>). Each of the drive gears (<NUM>, <NUM>) may be configured to mesh with a corresponding sun gear <NUM> fixed to strut cylinder <NUM>. Thereby, the collar <NUM> may be driven to rotate about the axis of the strut cylinder <NUM>. In various embodiments, the sun gear <NUM> may be fixed to the strut cylinder <NUM> by splines or dowels. In various embodiments, the sun gear <NUM> may be monolithic with the strut cylinder <NUM>. For example, the sun gear <NUM> may be a machined feature of the strut cylinder <NUM>. In various embodiments, the linear actuator <NUM> and the drive gears (<NUM>, <NUM>) may be enclosed by a housing <NUM> or other covering. In this regard, the components of the steering system <NUM> may be protected from harsh environments.

In various embodiments and with additional reference to <FIG>, steering system <NUM> is shown in axial cross section in a plane through the axis of the strut cylinder <NUM>. Collar <NUM> is coupled about the strut cylinder <NUM> and encloses the sun gear <NUM>. The drive gears (<NUM>, <NUM>) couple to the sun gear <NUM> via a portal <NUM> through the sidewall <NUM> of the collar <NUM>. In various embodiments the collar <NUM> is retained from sliding axially upward along the strut cylinder <NUM> by a shoulder <NUM> which protrudes radially from the strut cylinder <NUM>. In various embodiments, the collar <NUM> includes a reinforced portion <NUM> which extends from the upper surface of the collar <NUM> and abuts the shoulder <NUM>. In various embodiments, the collar <NUM> includes a retention feature <NUM>. The retention feature may be located opposite the upper surface of the collar <NUM> and configured to retain the sun gear <NUM> within the collar <NUM>. In various embodiments, the retention feature <NUM> may couple the collar <NUM> to the strut cylinder <NUM>. For example, the retention feature <NUM> may include a flange <NUM> and thereby tend to inhibit the collar from sliding axially downward along the strut cylinder <NUM>. In various embodiments, the retention feature <NUM> may be a nut or a segmented nut and may comprise inner threading <NUM> with the strut cylinder <NUM> and/or outer threading <NUM> with the collar <NUM>. In various embodiments, the nut may be coupled to the strut cylinder <NUM> to retain the sun gear <NUM> and provide a bearing surface for the collar <NUM> via the flange <NUM>.

With reference to <FIG> a steering system <NUM> in accordance with various embodiments. Steering system <NUM> comprises various features, materials, geometries, construction, manufacturing techniques, and/or internal components similar to steering system <NUM>. Steering system <NUM> differs in that it includes a second linear actuator arranged with the first linear actuator in a V configuration. It will be appreciated that any number of linear actuators may be arranged in this configuration to provide a desired motive power for the steering system <NUM>. The steering system <NUM> includes a steering collar <NUM>, a crankshaft <NUM>, a first drive gear <NUM>, a second drive gear <NUM> a first linear actuator <NUM>, and a second linear actuator <NUM>. In various embodiments, a first bearing mount <NUM> and a second bearing mount <NUM> extend orthogonally from the outermost diameter of the steering collar <NUM>. The crankshaft <NUM> may be coupled between the bearing mounts (<NUM>, <NUM>) and parallel to the axis of the strut cylinder <NUM>. In this regard, the crankshaft <NUM> may be free to rotate. Each of the first drive gear <NUM> and second drive gear <NUM> may be fixed to the crankshaft <NUM>.

In various embodiments and with additional reference to <FIG>, steering system <NUM> is shown in cross section through a plane orthogonal to the strut cylinder <NUM> through the first linear actuator <NUM> (<FIG>), in axial cross section in a plane through the axis of the strut cylinder <NUM> (<FIG>), and in cross section through a plane orthogonal to the strut cylinder <NUM> through the second linear actuator <NUM> (<FIG>). In various embodiments, the collar <NUM> may be coupled to a torque link <NUM>. Linear actuators (<NUM>, <NUM>) are illustrated as a piston-type linear actuator but it will be appreciated that any type (e.g., hydraulic, pneumatic, electrical, etc.) of linear actuator may be employed. In various embodiments, each linear actuator (<NUM>, <NUM>) is coupled to the crankshaft <NUM> at a corresponding first end. Each linear actuator (<NUM>, <NUM>) comprises a corresponding trunnion (<NUM>, <NUM>) at a second end distal of the first end. Collar <NUM> includes a first trunnion block <NUM> and a second trunnion block <NUM>. The trunnion blocks (<NUM>, <NUM>) extend radially from the sidewall <NUM> of the collar <NUM>. The trunnion blocks (<NUM>, <NUM>) are located circumferentially about the collar <NUM> proximate the portal <NUM> and such that the portal <NUM> is disposed relatively between the first trunnion block <NUM> and the second trunnion block <NUM>. In this regard, the linear actuators (<NUM>, <NUM>) are aligned relatively in a V configuration with each arm of the V comprising a linear actuator extending radially from the axis of the strut cylinder <NUM> with the corresponding second ends of the linear actuators (<NUM>, <NUM>) distal of each other.

In response to a command signal, the linear actuators (<NUM>, <NUM>) may cause rotation of the crankshaft <NUM> and thereby the drive gears (<NUM>, <NUM>). Each of the drive gears (<NUM>, <NUM>) may be configured to mesh with a corresponding sun gear <NUM> fixed to strut cylinder <NUM>. In various embodiments, the drive gears (<NUM>, <NUM>) couple to the sun gear <NUM> via a portal <NUM> through the sidewall <NUM> of the collar <NUM>. Thereby, the collar <NUM> may be driven to rotate about the axis of the strut cylinder <NUM>. In various embodiments, the sun gear <NUM> may be fixed to the strut cylinder <NUM> by splines or dowels. In various embodiments, the linear actuators (<NUM>, <NUM>) and the drive gears (<NUM>, <NUM>) may be enclosed by a housing <NUM> or other covering. In this regard, the components of the steering system <NUM> may be protected from harsh environments.

In various embodiments the collar <NUM> is retained from sliding axially upward along the strut cylinder <NUM> by a shoulder <NUM>. Shoulder <NUM> may protrude radially from the strut cylinder <NUM>. In various embodiments, the collar <NUM> includes a reinforced portion <NUM> which extends from the upper surface of the collar <NUM>. The reinforced portion <NUM> abuts the shoulder <NUM> and a contact generated therebetween may tend to retain the collar and thereby inhibit the collar from translating axially upward. In various embodiments, the collar <NUM> includes a retention feature <NUM>. The retention feature may be located opposite the upper surface of the collar <NUM> and configured to retain the sun gear <NUM> within the collar <NUM>. In various embodiments, the retention feature <NUM> may couple the collar <NUM> to the strut cylinder <NUM>. For example, the retention feature may include a flange <NUM> and thereby tend to inhibit the collar from sliding axially downward along the strut cylinder <NUM>. In various embodiments, the retention feature may be a nut or a segmented nut and may comprise inner threading <NUM> with the strut cylinder <NUM> and/or outer threading <NUM> with the collar <NUM>.

With additional reference to <FIG>, geometries of the crankshaft <NUM> and crankpin couplings to the linear actuators (<NUM>, <NUM>) are illustrated. The first linear actuator <NUM> is at full stroke with its line of action <NUM> passing through the crankshaft <NUM> axis of rotation A. In this configuration, the first linear actuator <NUM> delivers no torque to the crankshaft <NUM>. The second linear actuator <NUM> is configured to have a line of action <NUM> which is approximately <NUM>° (where approximately in this case means ±<NUM>°) from the axis A. The angle between the crank pin axes (B, C) of the linear actuators (<NUM>, <NUM>) relative to the axis A is approximately <NUM>° (where approximately in this case means ±<NUM>°). It will be appreciated that the line of action from the second linear actuator <NUM> should ideally be <NUM>° while the line of action from the first linear actuator <NUM> is <NUM>°. In this regard, the second linear actor <NUM> may provide torque to the crankshaft <NUM> and thereby enable steering control when the first linear actuator <NUM> is inhibited from providing torque and vice versa.

With reference to <FIG> a steering system <NUM> in accordance with various embodiments. Steering system <NUM> comprises various features, materials, geometries, construction, manufacturing techniques, and/or internal components similar to steering system <NUM>. Steering system <NUM> differs in that it includes a second linear actuator arranged with the first linear actuator in an in-line configuration. It will be appreciated that any number of linear actuators may be arranged in this configuration to provide a desired motive power for the steering system <NUM>. The steering system <NUM> includes a steering collar <NUM>, a crankshaft <NUM>, a first drive gear <NUM>, a first linear actuator <NUM>, and a second linear actuator <NUM>. In various embodiments, a first bearing mount <NUM> and a second bearing mount <NUM> extend orthogonally from the outermost diameter of the steering collar <NUM>. The crankshaft <NUM> may be coupled between the bearing mounts (<NUM>, <NUM>) and parallel to the axis of the strut cylinder <NUM>. In this regard, the crankshaft <NUM> may be free to rotate. The first drive gear <NUM> may be fixed to the crankshaft <NUM>.

In various embodiments and with additional reference to <FIG>, steering system <NUM> is shown in cross section through a plane orthogonal to the strut cylinder <NUM> through the first linear actuator <NUM> (<FIG>), in axial cross section in a plane through the axis of the strut cylinder <NUM> (<FIG>), and in cross section through a plane orthogonal to the strut cylinder <NUM> through the second linear actuator <NUM> (<FIG>). In various embodiments, the steering collar <NUM> may be coupled to a torque link <NUM>. Linear actuators (<NUM>, <NUM>) are illustrated as a piston-type linear actuator but it will be appreciated that any type (e.g., hydraulic, pneumatic, electrical, etc.) of linear actuator may be employed. In various embodiments, each linear actuator (<NUM>, <NUM>) is coupled to the crankshaft <NUM> at a corresponding first end. Each linear actuator (<NUM>, <NUM>) comprises a corresponding trunnion (<NUM>, <NUM>) at a second end distal of the first end. Steering collar <NUM> includes a first trunnion block <NUM> and a second trunnion block <NUM>. The trunnion blocks (<NUM>, <NUM>) extend radially from the sidewall <NUM> of the steering collar <NUM>. The trunnion blocks (<NUM>, <NUM>) are located circumferentially about the steering collar <NUM> proximate the portal <NUM> and such that the portal <NUM> is disposed relatively adjacent the same side of each of the first trunnion block <NUM> and the second trunnion block <NUM>. In this regard, the linear actuators (<NUM>, <NUM>) are aligned relatively in a row along the axis of the strut cylinder <NUM> with the corresponding second ends of the linear actuators (<NUM>, <NUM>) proximate each other.

In response to a command signal, the linear actuators (<NUM>, <NUM>) may cause rotation of the crankshaft <NUM> and thereby the drive gear <NUM>. The drive gear <NUM> may be configured to mesh with a corresponding sun gear <NUM> fixed to strut cylinder <NUM>. In various embodiments, the drive gear <NUM> couples to the sun gear <NUM> via a portal <NUM> through the sidewall <NUM> of the steering collar <NUM>. Thereby, the steering collar <NUM> may be driven to rotate about the axis of the strut cylinder <NUM>. In various embodiments, the sun gear <NUM> may be fixed to the strut cylinder <NUM> by splines or dowels. In various embodiments, the linear actuators (<NUM>, <NUM>) and the drive gear <NUM> may be enclosed by a housing <NUM> or other covering. In this regard, the components of the steering system <NUM> may be protected from harsh environments.

In various embodiments the steering collar <NUM> is retained from sliding axially upward along the strut cylinder <NUM> by a shoulder <NUM> which protrudes radially from the strut cylinder <NUM>. In various embodiments, the steering collar <NUM> includes a reinforced portion <NUM> which extends from the upper surface of the steering collar <NUM> and abuts the shoulder <NUM>. In various embodiments, the steering collar <NUM> includes a retention feature <NUM> opposite. The retention feature may be located opposite the upper surface of the steering collar <NUM> and configured to retain the sun gear <NUM> within the steering collar <NUM>. In various embodiments, the retention feature <NUM> may couple the collar <NUM> to the strut cylinder <NUM>. For example, the retention feature may include a flange <NUM> and thereby tend to inhibit the collar from sliding axially downward along the strut cylinder <NUM>. In various embodiments, the retention feature may be a nut or a segmented nut and may comprise inner threading <NUM> with the strut cylinder <NUM> and/or outer threading <NUM> with the steering collar <NUM>.

With additional reference to <FIG>, geometries of the crankshaft <NUM> and crankpin couplings to the linear actuators (<NUM>, <NUM>) are illustrated. The first linear actuator <NUM> is at full stroke with its line of action <NUM> passing through the crankshaft <NUM> axis of rotation A'. In this configuration, the first linear actuator <NUM> delivers no torque to the crankshaft <NUM>. The second linear actuator <NUM> is configured to have a line of action <NUM> which is approximately <NUM>° (where approximately in this case means ±<NUM>°) from the axis A'. The angle between the crank pin axes (B', C') of the linear actuators (<NUM>, <NUM>) relative to the axis A' is approximately <NUM>° (where approximately in this case means ±<NUM>°). It will be appreciated that the line of action from the second linear actuator <NUM> should ideally be <NUM>° while the line of action from the first linear actuator <NUM> is <NUM>°. In this regard, the second linear actor <NUM> may provide torque to the crankshaft <NUM> and thereby enable steering control when the first linear actuator <NUM> is inhibited from providing torque and vice versa.

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 disclosures.

The scope of the disclosures 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.

Claim 1:
A steering apparatus, comprising:
a steering collar (<NUM>) for coupling to an aircraft landing gear strut cylinder and including a sidewall (<NUM>) and a portal (<NUM>) through the sidewall (<NUM>);
a first linear actuator (<NUM>);
a first drive gear (<NUM>);
a crankshaft (<NUM>); and
a sun gear (<NUM>),
wherein the sun gear (<NUM>) is disposed within the steering collar (<NUM>),
wherein the first drive gear (<NUM>) is fixed to the crankshaft (<NUM>) and coupled to the sun gear (<NUM>) via the portal (<NUM>) such that the steering collar (<NUM>) rotates about the sun gear (<NUM>) in response to rotation of the crankshaft (<NUM>),
wherein the first linear actuator (<NUM>) is coupled between the crankshaft (<NUM>) and the steering collar (<NUM>).