Patent ID: 12209620

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

An aircraft, shown in the form of a rotary wing aircraft, is indicated generally at10inFIG.1in accordance with a non-limiting example. Aircraft10includes a fuselage12supporting a first driven system or main rotor14coupled to a gearbox16. A second driven system or tail rotor18is connected to a tail rotor gearbox20. A first drive system, shown as a first engine22and a second drive system, shown as second engine24are connected to gearbox16through a first shaft27and a second shaft29respectively. A third shaft35extends from gearbox16toward tail rotor18. Tail rotor gearbox20is connected to a tail rotor gear37through fourth shaft40. Tail rotor gear37creates a directional change between third shaft35and fourth shaft40. In a non-limiting example, third shaft35may be formed from a metal material. In another non-limiting example, third shaft35may be formed from a composite material. In other non-limiting examples, third shaft35can be a hybrid, i.e., formed from both metallic and composite components.

In a non-limiting example, third shaft35supports a flexible coupling50. Third shaft35includes a first shaft portion52that extends from first drive system22and second drive system24via gearbox16and a second shaft portion56that connects with tail rotor gear37. In a non-limiting example, flexible coupling50connects first shaft portion52with second shaft portion56. Flexible coupling50may absorb axial and lateral deviations between first shaft portion52and second shaft portion56along an axis defined by third shaft35. Another flexible coupling58may be employed to connect fourth shaft40with tail rotor gear37. Additional flexible couplings (not separately labeled) may be employed in connection with first shaft27and second shaft29.

Reference will now follow toFIGS.2-5, in describing flexible coupling50with an understanding that flexible coupling58can include similar structure. Flexible coupling50includes a first flange60mechanically and flexibly connected to a second flange62. First flange60includes a first body65having an outer edge67which, in the non-limiting example shown, is annular. First body65includes a first surface70and a second surface72. A first plurality of openings, one of which is indicated at74extends through first body65radially inwardly of outer edge67. Second flange62includes a second body78having an outer edge section80which, in the non-limiting example shown, is annular. Second body78includes a first surface section82and a second surface section84. A second plurality of openings, one of which is indicated at86extends through first body65radially inwardly of outer edge67.

In a non-limiting example, first flange60includes a first mounting section90projecting axially outwardly of first surface70. Second flange62includes a second mounting section92that projects axially outwardly from second surface section84. First mounting section90is connected to an outer surface94of first shaft portion52. Second mounting section92connects with an inner surface96of second shaft portion56. In a non-limiting example, second shaft portion56takes the form of a tube98.

In a non-limiting example, a connecting element103extends through each of the first plurality of passages74and second plurality of passages86flexibly linking first flange60and second flange62as shown inFIG.2as an axial partial cross-sectional view and inFIG.3as a diametric view. Connecting elements103transmit torque between first flange60and second flange62. Connecting element103includes a connecting member105having a first end108, a second end110, and an intermediate portion112extending between first end108and second end110. A first stop element114is arranged at first end108. A second stop element116is arranged at second end110. First and second stop elements114and116may be fixedly attached to connecting member105in one non-limiting example. In another non-limiting example, one, another, or both of first stop element114and second stop element116is detachably mounted to connecting member105.

In a non-limiting example, connecting element103supports one or more compliant components. Referring toFIG.2, a first compliant component119is positioned on connecting member105between first stop element114and first surface70, a second compliant component121is positioned on connecting member105between second surface72and first surface section82, and a third compliant component arranged between second surface section84and second stop element116. In a non-limiting example, first compliant component119may take the form of a first coil spring128, second compliant component121may take the form of a second coil spring130, and third compliant component123may take the form of a third coil spring132. In other embodiments, compliant components can be designed as any combination of coil helical, conical, disk or Belleville, and machined springs.

In a non-limiting example, first, second, and third compliant components119,121, and123react to service conditions that are aligned with third shaft35or displacements due to axial or bending misalignments such as compression as shown inFIG.4and tension as shown inFIG.5. First, second, and third compliant components119,121, and123may also react to conditions that may result in excursions of first shaft portion52and/or second shaft portion56from the axis defined by third shaft35or “off-torsional” displacements. Under compression, first compliant component119and second compliant component121may be compressed while third compliant component123may be stretched. Under tension, first compliant component119and second compliant component121may be stretched and third compliant component123may be stretched. In this manner, not only does flexible coupling58transmit torque along third shaft35but also supports changes in axial and/or bending displacements due to operating conditions.

In accordance with a non-limiting example depicted inFIG.6, second compliant component121may be moved from connecting member105radially inwardly. In the exemplary embodiment shown, second compliant component121is directly connected between second surface72and first surface section82radially inwardly of first mounting section90and second mounting section92.

FIGS.7-9depict non-limiting examples in which only two compliant components are employed. InFIG.7, first compliant component119is omitted. InFIG.8, third compliant component123is omitted. In each case, when subjected to compression, second compliant component121is compressed and third compliant component123(FIG.7) is stretched or first compliant component119(FIG.8) is stretched. In tension, second compliant component121is stretched and either third compliant component123(FIG.7) is compressed or first compliant component119(FIG.8) is compressed. InFIG.9, second compliant component121is omitted and a gap138is maintained between first flange60and second flange62to accommodate movement of first shaft portion52relative to second shaft portion56. In a non-limiting example, first compliant component119is connected to each of first stop element114and first surface70. That is, each end (not separately labeled) of first compliant component119is fixedly connected to corresponding ones of first stop element114and first surface70. Similarly, third compliant component123connected to second stop element116and to second surface section84. That is, each end (not separately labeled) of third compliant component123is fixedly connected to corresponding ones of second stop element116and second surface section84.

FIGS.10-13depict non-limiting examples in which only a single compliant component is employed. InFIG.10, second compliant component121is disposed between first flange60and second flange62, i.e., between the second surface72and the first surface sections82. A gap141is maintained between first stop element114and first surface70by connecting ends of the compliant component to second section72and the first surface section82, accordingly. It should be understood that gap141could, in accordance with another non-limiting example, be similarly arranged between second surface section84and second stop element116as shown inFIG.11. In accordance with another non-limiting example, second compliant component121and third compliant component123may be omitted as shown inFIG.12. A gap147is maintained between second surface72and first surface section82to allow for relative movement. In accordance with another non-limiting example shown inFIG.13, first compliant component119and second compliant component121may be omitted with gap147being maintained between second surface72and first surface section82.

FIG.14-16depict compliant components in accordance with another non-limiting example. A first compliant component154is disposed between first stop element114and first surface70, a second compliant component156is disposed between second surface72and first surface section82, and a third compliant component158is disposed between second surface section84and second stop element116. First, second, and third compliant components154,156, and158take the form of resilient bushings that react in a manner similar to that of springs to compression (FIG.15) and tension (FIG.16). The bushing can be made of any suitable elastomeric materials, such as synthetic and natural rubber, polyurethane, and/or different types of low stiffness appropriate polymers. First, second, and third compliant components154,156, and158may take the form of discrete elements in accordance with one non-limiting example or as shown inFIG.17, a continuous annular resilient bushing166in accordance with another non-limiting example.

FIG.18depicts opening74in first flange60. It should be understood that second flange62may be similarly formed. In a non-limiting example, opening74includes an annular wall170defined by a curvilinear surface171having a constant radius. In a non-limiting example, it should be understood that curvilinear surface171may also be formed with a non-uniform radius. In another non-limiting example, surface171can include both, at least one, curvilinear segment, either with uniform or non-uniform radius and, at least one, linear segment. Curvilinear surface171is designed to accommodate lateral deviates of connecting member105so as to minimize any stress concentration zones in first flange60and/or in second flange62.FIG.19depicts similar opening74having an annular wall180including a first taper or chamfer182at first side70and a second taper or chamfer184at second side72. In a manner similar to that discussed herein, first and second tapers182and184are designed to accommodate lateral deviates of connecting member105so as to minimize any stress concentration zones in flange60.

In accordance with the non-limiting examples described herein, stiffness properties of compliant components can be designed to meet to specifics of applications and expected service conditions. The stiffness properties are functions of design characteristics of the compliant components, such as, for example, spring type, length, cross-sectional geometry, applied materials, etc. Also, non-limiting examples that employ more than one compliant component per individual connecting element, corresponding stiffness properties may be adjusted between such components, i.e., depending on applications, the compliant components can be the same or different.

At this point, it should be understood that the non-limiting examples described herein present a flexible coupling that links two shafts and accommodates on axis movement (e.g., compression and tension) as well as off-axis movement (e.g., bending). The flexible coupling is easy to manufacture and may be readily configured and reconfigured to accommodate a wide range of operating environments.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.