Patent Description:
The present disclosure relates to landing gear of aircraft and, more particularly, to a tripod landing gear assembly.

Many aircraft include landing gear having wheel assemblies to allow the aircraft to travel along the ground during taxi, takeoff, and landing. A tripod main landing gear assembly may be beneficial structurally due to unidirectional loading in each one of the primary members of the landing gear. Typical tripod landing gear assemblies utilizes a toggle lock arrangement between braces that fold up and allow stowage in a bay of an aircraft. A toggle lock may be less stable than desired for a tripod landing gear assembly. A toggle lock may experience undesirable dynamics during operation of a typical tripod landing gear assembly. <CIT> describes a method for maneuvering an aircraft undercarriage. The method involves using a rotary electromechanical type drive actuator coupled to a portion of the undercarriage in order to raise it from the deployed position to the retracted position. <CIT> describes a landing gear with a realigning lock link assembly. <CIT> describes a landing gear. <CIT> describes aircraft landing gear. <CIT> describes an aircraft landing gear assembly. <CIT> describes an aircraft landing gear assembly.

According to a first aspect, there is provided a tripod landing gear assembly for use with an aircraft according to claim <NUM>.

Further optional features are mentioned in the dependent claims <NUM>-<NUM>.

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 disclosure. 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 may include multiple landing gear including a first landing gear <NUM>, a second landing gear <NUM>, and a third landing gear <NUM>. In various embodiments, the second landing gear <NUM> and the third landing gear <NUM> may be main landing gear and the first landing gear <NUM> may be a nose landing gear. Each landing gear may include one or more wheel assemblies. For example, the first landing gear <NUM> includes one wheel assemblies <NUM>. The landing gear <NUM>, <NUM>, <NUM> and the wheel assemblies <NUM> support the aircraft <NUM> in response to the aircraft <NUM> being parked and during taxi, takeoff, and landing of the aircraft <NUM>.

The aircraft <NUM> may further include one or more gas turbine engine <NUM>. The gas turbine engine <NUM> may be controlled by a pilot (such as by controlling a throttle in a cockpit) to generate thrust to accelerate the aircraft <NUM>. The gas turbine engine <NUM> may include a nacelle <NUM>.

An X-Y-Z axis is shown throughout the drawings to illustrate the relative orientation of various components.

Referring now to <FIG> and <FIG>, the landing gear <NUM> may include a system <NUM> for supporting the landing gear <NUM>. The landing gear <NUM> may be used as any landing gear such as the landing gear <NUM>, <NUM>, or <NUM> of <FIG>, a nose landing gear, a main landing gear, an auxiliary landing gear, or the like. The system <NUM> may notably facilitate locking of the landing gear <NUM> in a down and locked position (as shown in <FIG>) and in a stowed position (as shown in <FIG>) without use of an up-lock, and with only the drag brace assembly <NUM> and the jury linkage <NUM>. This desirably reduces complexity and part count of the landing gear <NUM>, also reducing a total weight of the landing gear <NUM>. The system <NUM> further facilitates storage of the landing gear <NUM> in a relatively small compartment.

The system <NUM> may include a drag brace assembly <NUM> having an upper brace <NUM> and a lower brace <NUM>. The system <NUM> may further include a jury linkage <NUM> having a brace portion <NUM> and a strut portion <NUM>. The system <NUM> may also include a shock strut <NUM> having an outer cylinder <NUM> and an inner cylinder <NUM>.

The upper brace <NUM> of the drag brace assembly <NUM> may have an upper end <NUM> that is designed to be rotatably connected to an aircraft structure. The lower brace <NUM> of the drag brace assembly <NUM> may have a lower end <NUM> designed to be rotatably coupled to the shock strut <NUM>. For example, the lower end <NUM> may be rotatably coupled to the outer cylinder <NUM> of the shock strut <NUM>. The upper brace <NUM> of the drag brace assembly <NUM> may be pivotally coupled to the lower brace <NUM> at a center point <NUM>.

The brace portion <NUM> of the jury linkage <NUM> may have a brace end <NUM> that is pivotally coupled to the drag brace assembly <NUM>. In various embodiments, the brace end <NUM> may be pivotally coupled to the center point <NUM> of the drag brace assembly <NUM>. In that regard, the brace end <NUM>, the upper brace <NUM>, and the lower brace <NUM> may each be pivotally coupled together at a single location <NUM>. In various embodiments, the brace end <NUM>, the upper brace <NUM>, and the lower brace <NUM> may each be pivotally coupled together at the center point <NUM> using a single pin <NUM> at the single location <NUM>. The single location <NUM> may be located along a pivot axis A-A'. The pivot axis A-A' may be an axis about which the elements may pivot and may be defined as a single pin <NUM> axis.

The strut portion <NUM> of the jury linkage <NUM> may have a strut end <NUM> that is rotatably coupled to the shock strut <NUM>. In various embodiments, the strut end <NUM> may be rotatably coupled to the outer cylinder <NUM> of the shock strut <NUM>.

The brace portion <NUM> of the jury linkage <NUM> and the strut portion <NUM> of the jury linkage <NUM> may be pivotally coupled together at a jury center point <NUM>. In that regard, the jury linkage <NUM> may be referred to as a reshaping jury linkage <NUM> as it may reform, restructure, or reshape as the landing gear <NUM> changes states between the down and locked position and the stowed position. A length P of the jury linkage <NUM> may be extended in a straight line in response to the landing gear being in the stowed position, thus locking the landing gear <NUM> in the stowed position. Likewise, the length P of the jury linkage <NUM> may be extended in a straight line in response to the landing gear being in the down and locked position, again locking the landing gear <NUM> in the down and locked position.

The inner cylinder <NUM> of the shock strut <NUM> may be at least partially located within the outer cylinder <NUM> of the shock strut <NUM>. One or more wheel assembly <NUM> may be coupled to the inner cylinder <NUM> of the shock strut <NUM>. In response to the wheel assembly <NUM> contacting a ground surface, the inner cylinder <NUM> may be further received by the outer cylinder <NUM> and displacing a fluid, thus providing shock absorption for the landing gear <NUM>.

The outer cylinder <NUM> of the shock strut <NUM> may have a strut attachment <NUM>. The strut attachment <NUM> may be designed to be coupled to a portion of a corresponding aircraft. In various embodiments, the strut attachment <NUM> may be pivotally coupled to the aircraft.

The rotatable connections or couplings between components may be facilitated using spindle joints. In particular, an upper drag spindle joint <NUM> may be located on, or coupled to, the upper end <NUM> of the drag brace assembly <NUM>. The upper drag spindle joint <NUM> may likewise be coupled to a portion of the aircraft. In that regard, the drag brace assembly <NUM> may rotate freely relative to the portion of the aircraft to which the upper drag spindle joint <NUM> is attached.

A lower drag spindle joint <NUM> may be located on, or coupled to, the lower end <NUM> of the drag brace assembly <NUM>. The lower drag spindle joint <NUM> may likewise be coupled to the outer cylinder <NUM> of the shock strut <NUM>. In that regard, the drag brace assembly <NUM> may rotate freely relative to the portion of the outer cylinder <NUM> to which the lower drag spindle joint <NUM> is attached.

A jury spindle joint <NUM> may be located on, or coupled to, the strut end <NUM> of the jury linkage <NUM>. The jury spindle joint <NUM> may likewise be coupled to the outer cylinder <NUM> of the shock strut <NUM>. In that regard, the jury linkage <NUM> may rotate freely relative to the portion of the outer cylinder <NUM> to which the jury spindle joint <NUM> is attached.

As referenced above, <FIG> illustrates the landing gear <NUM> in a down and locked position, and <FIG> illustrates the landing gear <NUM> in a stowed position. The jury linkage <NUM> may be positioned in a line (i.e., the brace portion <NUM> and the strut portion <NUM> may be aligned along a same axis) in response to the landing gear <NUM> being in the stowed position and in the down and locked position. The jury linkage <NUM> may be folded (i.e., may form two lines at an angle) during the transition from the stowed position to the down and locked position.

The drag brace assembly <NUM> may be positioned in a straight line (i.e., the upper brace <NUM> and the lower brace <NUM> may be aligned along a same plane, as defined by the three rotation axes defined by the spindle joints <NUM>, <NUM>, <NUM>) in response to the landing gear <NUM> being in the down and locked position. The drag brace assembly <NUM> may be angled in response to the landing gear <NUM> being in the stowed position. In that regard and in response to the drag brace assembly <NUM> being angled, an angle <NUM> may exist between the upper brace <NUM> and the lower brace <NUM>. In various embodiments, the angle <NUM> may be less than <NUM> degrees (i.e., between <NUM> degrees and <NUM> degrees), less than <NUM> degrees (i.e., between <NUM> and <NUM> degrees), less than <NUM> degrees (i.e., between <NUM> and <NUM> degrees), or the like.

As illustrated in the drawings, the plane of the landing gear <NUM> shifts as the landing gear <NUM> is changed between the down and locked position and the stowed position. In particular, the components of the landing gear <NUM> are aligned in the Y-Z plane in response to the landing gear being in the down and locked position. The plane of the components changes somewhat out of the Y-Z plane such that the components are aligned at least partially in the X-Y plane in response to the landing gear being in the stowed position. Such repositioning of the plane is facilitated by the reforming jury linkage <NUM> along with the rotatable couplings of the various components.

Referring now to <FIG>, the tripod landing gear assembly <NUM> may include a system <NUM> for supporting the landing gear <NUM>. The tripod landing gear assembly <NUM> may be used as any main landing gear, such as the landing gear <NUM> or <NUM> of <FIG>. The system <NUM> may notably facilitate locking of the tripod landing gear assembly <NUM> in a down and locked position (as shown in <FIG>) and in a stowed position without use of a toggle lock. This desirably reduces complexity and part count of the tripod landing gear assembly <NUM>, also reducing a total weight of the tripod landing gear assembly <NUM>. The system <NUM> further facilitates storage of the tripod landing gear assembly <NUM> in a relatively small compartment.

The system <NUM> includes a drag brace assembly <NUM> having an upper brace <NUM> and a lower brace <NUM>. The lower brace <NUM> may comprise a brace, a strut, or the like. The system further includes a tension strut assembly <NUM>. The system <NUM> further includes a jury linkage <NUM>. In various embodiments, the jury linkage <NUM> may be rotatably coupled to the drag brace assembly <NUM> at an intersection of the upper brace <NUM> and the lower brace <NUM>. In various embodiments, the jury linkage <NUM> may include a brace portion and a strut portion in accordance with jury linkage <NUM>. In various embodiments, jury linkage <NUM> may only include a brace, such as brace portion <NUM> from jury linkage <NUM>. In various embodiments, in embodiments where jury linkage <NUM> comprises a reforming jury linkage (e.g., jury linkage <NUM>), the system allows for elimination of an up lock actuator and a down lock actuator. In various embodiments, in embodiments where jury linkage <NUM> comprises a brace only, the system <NUM> may still benefit by providing a more stable lock for the tripod landing gear assembly <NUM> relative to typical tripod landing gear assemblies with toggle locks. The system <NUM> further includes a shock strut <NUM> having an outer cylinder <NUM> and an inner cylinder <NUM>.

The upper brace <NUM> of the drag brace assembly <NUM> may have an upper end <NUM> that is designed to be rotatably connected to an aircraft structure. The lower brace <NUM> of the drag brace assembly <NUM> may have a lower end <NUM> designed to be fixedly coupled to the tension strut assembly <NUM>. The upper brace <NUM> of the drag brace assembly <NUM> may be pivotally coupled to the lower brace <NUM> at a center point <NUM>.

A brace end <NUM> of the jury linkage <NUM> may be pivotally coupled to the drag brace assembly <NUM>. In various embodiments, the brace end <NUM> may be pivotally coupled to the center point <NUM> of the drag brace assembly <NUM>. In that regard, the brace end <NUM>, the upper brace <NUM>, and the lower brace <NUM> may each be pivotally coupled together at a single location <NUM>. In various embodiments, the brace end <NUM>, the upper brace <NUM>, and the lower brace <NUM> may each be pivotally coupled together at the center point <NUM> using a single pin <NUM> at the single location <NUM>. The single pin <NUM> may be define a pivot axis along a centerline of the single pin <NUM>. The pivot axis may be an axis about which the elements may pivot.

The jury linkage <NUM> may have a second end <NUM> that is rotatably coupled to the tension strut assembly <NUM>. The second end <NUM> may be a second brace end when jury linkage <NUM> includes a brace portion only, or the second end <NUM> may be a strut end when jury linkage <NUM> is a reforming jury linkage (e.g., jury linkage <NUM>).

The inner cylinder <NUM> of the shock strut <NUM> may be at least partially located within the outer cylinder <NUM> of the shock strut <NUM>. A wheel assembly <NUM> may be coupled to the tension strut <NUM> of the tension strut assembly <NUM>. The inner cylinder <NUM> may be pivotably coupled to the tension strut <NUM> of the tension strut assembly <NUM>. In response to the wheel assembly <NUM> contacting a ground surface, the inner cylinder <NUM> may be further received by the outer cylinder <NUM> and displacing a fluid, thus providing shock absorption for the tripod landing gear assembly <NUM>.

The rotatable connections or couplings between components may be facilitated using spindle joints. In particular, an upper drag spindle joint <NUM> may be located on, and/or coupled to, the upper end <NUM> of the drag brace assembly <NUM>. The upper drag spindle joint <NUM> may likewise be coupled to a portion of the aircraft. In that regard, the drag brace assembly <NUM> may rotate freely relative to the portion of the aircraft to which the upper drag spindle joint <NUM> is attached.

The upper tension strut spindle joint <NUM> may be located on, and/or coupled to, a middle portion <NUM> of tension strut <NUM>. The upper tension strut spindle joint <NUM> may likewise be coupled to the second end <NUM> of the jury linkage <NUM>. In that regard, the jury linkage <NUM> may rotate freely relative to the tension strut <NUM> to which the upper tension strut spindle joint <NUM> is attached.

The lower tension strut spindle joint <NUM> may be located on, and/or coupled to, a lower end <NUM> of the tension strut <NUM>. The lower tension strut spindle joint <NUM> may likewise be coupled to the lower end <NUM> of the drag brace assembly <NUM>. In that regard, the drag brace assembly <NUM> may rotate freely relative to the lower end <NUM> of the tension strut <NUM> to which the lower tension strut spindle joint <NUM> is attached.

As referenced above, <FIG> illustrates the tripod landing gear <NUM> in a down and locked position. The jury linkage <NUM> may be positioned in a line (i.e., the brace portion and the strut portion may be aligned along a same axis when the jury linkage is a reforming jury linkage (e.g., jury linkage <NUM>) in response to the tripod landing gear assembly <NUM> being in the down and locked position. The jury linkage <NUM> may be folded (i.e., may form two lines at an angle) during the transition from the stowed position to the down and locked position and vice versa when the jury linkage <NUM> is a reforming jury linkage (e.g., jury linkage <NUM>). In various embodiments, when jury linkage <NUM> is a brace only, the jury linkage may maintain a straight line between drag brace assembly <NUM> and tension strut assembly <NUM> during the transition from the stowed position to the down and locked position, and vice versa.

The drag brace assembly <NUM> may be positioned in a straight line (i.e., the upper brace <NUM> and the lower brace <NUM> may be aligned along a same plane, as defined by the three rotation axes defined by the spindle joints <NUM>, <NUM>, <NUM>) in response to the tripod landing gear assembly <NUM> being in the down and locked position. The drag brace assembly <NUM> may be angled in response to the landing gear <NUM> being in the stowed position. In that regard and in response to the drag brace assembly <NUM> being angled, an angle may exist between the upper brace <NUM> and the lower brace <NUM> about center point <NUM>. In various embodiments, the angle may be less than <NUM> degrees (i.e., between <NUM> degrees and <NUM> degrees), less than <NUM> degrees (i.e., between <NUM> and <NUM> degrees), less than <NUM> degrees (i.e., between <NUM> and <NUM> degrees), or the like.

A plane of the tripod landing gear assembly <NUM> shifts as the tripod landing gear assembly <NUM> is changed between the down and locked position and the stowed position. In particular, the components of the tripod landing gear assembly <NUM> are aligned in a plane defined by a tension strut centerline <NUM>, defined by a centerline of the tension strut <NUM>, and a lower drag brace centerline <NUM> of lower drag brace <NUM>. In this regard, lower drag brace centerline <NUM> and the tension strut centerline <NUM> intersect. During the transition from the stowed position to the down and locked position, and vice versa, the tripod landing gear assembly <NUM> rotates along the plane defined by the tension strut centerline <NUM> and the lower drag brace centerline <NUM>. In various embodiments, a jury linkage centerline <NUM>, defined by a centerline of the jury linkage <NUM>, is in the plane defined by the tension strut centerline <NUM> and the lower drag brace centerline <NUM>.

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.

Claim 1:
A tripod landing gear assembly (<NUM>) for use with an aircraft, the tripod landing gear assembly comprising:
a shock strut having an outer cylinder (<NUM>) configured to be coupled to the aircraft, and an inner cylinder (<NUM>);
a drag brace assembly (<NUM>) having an upper brace (<NUM>) configured to be rotatably coupled to the aircraft and a lower brace (<NUM>) pivotably coupled to the upper brace;
a tension strut (<NUM>) extending from an upper end to a lower end, the lower brace rotatably coupled to the tension strut proximate the lower end of the tension strut;
a jury linkage (<NUM>) pivotally coupled to the drag brace assembly and rotatably coupled to the tension strut;
an upper drag spindle joint (<NUM>) configured to rotatably couple a drag brace upper end (<NUM>) of the drag brace assembly to the aircraft, the drag brace assembly configured to rotate relative to the aircraft;
an upper tension strut spindle joint (<NUM>), which rotatably couples the jury linkage to a middle portion (<NUM>) of the tension strut, the jury linkage (<NUM>) being configured to rotate relative to the tension strut;
a lower tension strut spindle joint (<NUM>), which rotatably couples a drag brace lower end of the drag brace assembly to a lower portion of the tension strut, the lower portion being between the lower end and the middle portion, proximate the lower end, the drag brace assembly being configured to rotate relative to the tension strut; wherein the tension strut defines a tension strut centerline and the lower brace defines a lower brace centerline; and wherein the tripod comprises
a plane defined by the tension. strut centerline and the lower drag brace centerline, wherein a jury linkage centerline is disposed within the plane, and wherein the plane shifts as the tripod landing gear assembly is changed between a down and locked position to a stowed position, and wherein the inner cylinder is coupled to the tension strut between the upper tension strut spindle joint and the lower tension strut spindle joint.