BACKGROUND OF THE INVENTION
1. Field of the Invention
The present disclosure relates to flexible couplings, and more particularly to
S diaphragm couplings with features designed to limit angular bending.
2. Description of Related Art
Flexible couplings are commonly used to transmit torque while accommodating
axial and/or angular misalignment between driving and driven shaft components along a
load path. The flexible couplings generally have stiffness that opposes the angular
1 0 misalignment accommodated by the flexible coupling. In some flexible couplings, such
as flexible couplings with relatively low spring rates, it can be possible to overstress the
flexible coupling, either during installation or removal of the flexible coupling. Some
flexible couplings can also be overstressed while transmitting torque between rotation
shafts when the angular misalignment between the interconnected shafts exceeds a
15 predetermined angular misalignment.
Such conventional methods and systems have generally been considered
satisfactory for their intended purpose. However, there is still a need in the art for
improved flexible couplings for transmitting torque between rotating members while
accommodating misalignment between the members. The present disclosure provides a
20 solution for this need.
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SUMMARY OF THE INVENTION
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A flexible coupling includes a flexure, a first drive member defining an axis and
connected to the flexure, and a second drive member defining an axis and connected to
the flexure on a side of the flexure opposite the first drive member. An angular stop is
5 fixed within the first drive member, extends through at least a portion of the second drive
member, and is arrange to limit angular misalignment of the first drive member axis
relative to the second drive member axis while transmitting torque between the first and
second drive members. For purposes of illustration, the first drive member will be
considered the end with the splined shaft and the second drive member will be considered
10 the end with the bolted flange. Those skilled in the art will readily understand that either
end could be considered the first and second member and that the ends of the coupling
could include other types of input or output devices.
The first drive member is connected to the first end of a diaphragm coupling and
includes a body, a seat, and an angular stop. The seat extends from the body and is
15 connected to the diaphragm coupling. The angular stop extends from the body and is
axially overlapped by the seat and the second member to limit bending of the diaphragm
coupling.
In certain .embodiments, a bore can extend through the second member. The bore
provides for lower mass of the overall coupling system and may be larger, smaller, or
20 non-existent depending on the requirements of the application.
The first member includes a body and seat. The body includes a bore which
extends through the first member and provides for an annular gap between the angular
stop and the output body. In accordance with certain embodiments, the annular gap can
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be defined within the flexible coupling. The radial width of the annular gap bounded by
the output body and the angular stop allows for a limited amount of angular motion
between the first and second members.
A drive train system includes mechanical rotation source, a driving shaft, a driven
5 shaft, driven element, and a flexible coupling as described above. The driving shaft is
connected to the first drive member. The mechanical rotation source is connected to the
first drive member by the driving shaft. The driven shaft is connected to the second drive
member. The driven element is connected to the second drive member by the driven
shaft. In certain embodiments the driven element is a rotor assembly for a rotorcraft.
10 Those skilled in the art will readily understand that first and second members may
be constructed as one-piece structures having respective flexible diaphragms, a single
weld connecting outer rims of the flexible diaphragms connect the first member to the
second member. Either or both of the first and second members, or the entire coupling,
can be fabricated using a subtractive manufacturing technique, such as by removing
15 material from an interior of a piece of stock material and machining material from the
exterior of the piece of stock material. Either or both of the first and second members can
be fabricated using an additive manufacturing technique, such as powder bed fusion by
way ofnon-limiting.ex.ample.
These and other features of the systems and methods of the subject disclosure will
20 become more readily apparent to those skilled in the art from the following detailed
description of the preferred embodiments taken in conjunction with the drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
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So that those skilled in the art to which the subject disclosure appertains will
readily understand how to make and use the devices and methods of the subject
disclosure without undue experimentation, embodiments thereof will be described in
5 detail herein below with reference to certain figures, wherein:
Fig. I is a schematic view of an exemplary embodiment of a drive train system
constructed in accordance with the present disclosure, showing a flexible coupling
connecting a driving member with a driven member;
Fig. 2 is a cross-sectional side view of the flexible coupling of Fig. 1, showing a
10 first drive member with an angular stop connected to a second drive member by a
flexure;
Fig. 3 is a cross-sectional side view of a portion of the flexible coupling of Fig. 1,
showing an annular gap defined within an interior of the flexible coupling between the
angular stop and the first and second drive members;
15 Figs. 4 and 5 are cross-sectional end views of the flexible coupling illustrated in
Fig. I, showing the angular stop in first and second positions, the angular stop allowing
bending in the first position and constraining bending in the second position; and
Fig. 6 is.a.crosscsecti.onal side of another embodiment of the flexible coupling a
Fig. 1, showing a two-piece diaphragm coupling including a first drive member
20 connected to a second drive member by a single weld.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made to the drawings wherein like reference numerals
identify similar structural features or aspects of the subject disclosure. For purposes of
explanation and illustration, and not limitation, a partial view of an exemplary
5 embodiment of a flexible coupling in accordance with the disclosure is shown in Fig. 1
and is designated generally by reference character l 00. Other embodiments of flexible
couplings, drive train systems, and methods of installing, removing, and transmitting
torque while accommodating misalignment between driving and driven members in
accordance with the disclosure, or aspects thereof, are provided in Figs. 2-6, as will be
I 0 described. The systems and methods described herein can be used for drive train systems
such as in rotorcraft, though the present disclosure is not limited to rotorcraft or to aircraft
in general.
Referring to Fig. I, a vehicle 10, e.g., a rotorcraft, is shown. Vehicle 10 includes
a mechanical rotation source 12 operably connected to a driven element 14 by a drive
15 train system 16. Drive train system 16 includes a driving member 18, a flexible coupling
100 with a first drive member I 02 and a second drive member 104, and a driven member
20. First drive member 102 defines an axis 26. Second drive member 104 defines an
axis 28. Drive train.system.l6 transmits torque T via flexible coupling I 00 between
mechanical rotation source 12 and driven element 14 while accommodating one or more
20 axial misalignment 22 (shown with dotted-dashed line and indicated by offset dimension
D) between first drive member I 02 and second drive member 104 and angular
misalignment 24 (shown in dashed line and indicated by angle indicator alpha) between
axes defined by first drive member I 02 and second drive member J 04. As used herein,
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the term misalignment can refer to either or both of axial misalignment and angular
misalignment.
Mechanical rotation source 12 may include a motor or an engine, such as a gas
turbine engine, and is connected to driving member 18. Driving member 18 is connected
5 to first drive member 102 of flexible coupling 100. Driven member 20 is connected to
second drive member 104. Driven element 14 is connected to driven member 20 may
include, by way of non-limiting example, a rotor assembly. Although flexible coupling
1 00 is described herein as transmitting torque T from first drive member 102 to second
drive member 104, it is to be understood and appreciated that torque can also be
I 0 transmitted from second drive member 104 to first drive member 102, as suitable for an
intended application.
With reference to Fig. 2, flexible coupling 100 is shown. Flexible coupling I 00
includes first drive member 102, second drive member 104, and a flexure 108. First drive
member 102 is connected to flexure 108. First drive member 102 defines an internal bore
15 110 and includes a body 112, a seat 114, and an angular stop 116. Seat 114 extends
axially from body 112 and is connected to flexure 108 opposite second drive member I 04.
Bore 110 tapers from a first width A defined within body 112 to a second width B
defined within angularstop . .ll6. Second drive member 104 defines a bore 106 which, in
conjunction with bore 110 of first drive member, defines an open through-bore extending
20 through flexible coupling 100. As will be appreciated by those of skill in the art in view
of the present disclosure, the open through-bore collectively formed by bore 110 and bore
I 06 has no internal contacting surfaces, which potentially could wear against one another.
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Angular stop 116 extends axially from body 112 and is axially overlapped by at
least a portion of second drive member 104. A radial gap I 07 separates angular stop 116
from seat 114, flexure 108, and a portion of second drive member 104 to constrain
bending of flexure 108 associated by angular misalignment of first drive member I 02
5 relative to second drive member 104. As will be appreciated by those of skill in the art in
view of the present disclosure, angular misalignment can result from manipulation of
flexible coupling 100 during installation and/or removal as well as from misalignment
within elements of drive train system 16 (shown in Fig. 1) accommodated while
transmitting torque T (shown in Fig. 1).
10 Flexure 108 includes a plurality of diaphragm elements extending between inner
hub and outer rims and interposed between first drive member 102 and second drive
member 104. While shown in the illustrated exemplary embodiments as having
diaphragm elements, it is to be understood and appreciated that flexure l 08 can include
other types of flexure structures such as a bellows coupling, a helical coupling, or any
15 other flexible coupling where one of either the input shaft or the output may overlap in
this type of geometry, as suitable for an intended application. As shown in Fig. 2, flexure
108 includes a first diaphragm element 126 and a second diaphragm element 128. This is
for illustration purposes only and is non-limiting as flexure I 08 can include a single
diaphragm element or more than two diaphragm elements, as suitable for an intended
20 application. Although flexure I 08 is illustrated in the exemplary embodiment as a
diaphragm element, it is to be understood and appreciated that other types of flexures,
such as disks, gears, flex frames, universal joints, and elastomericjoints by way of nonlimiting
example can also benefit from the present disclosure.
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First diaphragm element 126 has flexible diaphragm portion 130 extending
radially between an inner hub 132 and an outer rim 134. Second diaphragm element 128
is similar to first diaphragm element 126 and includes a flexible diaphragm portion 136
extending between an inner hub 138 and an outer rim 140. Either or both of flexible
5 diaphragm portion 130 and 136 may be arranged to taper in axial thickness to a radial
location of minimum thickness between the respective inner hub and outer hub. In this
respect either or both of first diaphragm element 126 and second diaphragm element 128
may be, for example, as described in U.S. Patent No. 8,591,345 to Stocco et al., the
contents of which are incorporated herein by reference in it is entirety.
10 Referring to Figs. 2 and 3, first diaphragm element inner hub 132 is coupled to
first drive member seat 114. The coupling may be, for example, through a first weld 142.
First diaphragm element 126 couples to outer rim 140 of second diaphragm element 128
at outer rim 134. The coupling between first diaphragm element 126 and second
diaphragm element 128 may be, for example, through an intermediate weld 143. Second
15 diaphragm element 128 couples at inner hub 138 to second drive member 104. The
coupling between inner hub 138 and second drive member I 04 may be, for example,
through a second weld 144.
As will be.11ppreciated by those of skill in the art, connecting elements of flexible
coupling I 00 using welds eliminates contacting surfaces at element interfaces, removing
20 potential sources of wear that such contacting surfaces could otherwise pose in flexible
coupling 100. Either or both of first weld 142 and second weld 144 may include a 90
degree weld extending about an axial collar first drive member 102 and/or second drive
member 104, the axial collar facilitating assembly off1exible coupling 100 by providing
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registration of flexure 108 relative first drive member 102 and/or second drive member
104 during assembly. Such welds can also facilitate the transfer of bending loads while
transmitting torque and accommodating misalignment between first drive member l 02
and second drive member 104.
With continuing reference to Fig. 2, first drive member 102 includes a spline 118.
Spline 118 is defined on a radially outer surface of first drive member 102, and is
arranged for rotatably fixing flexible coupling 100 to driving member 18 (shown in Fig.
1) such that flexible coupling l 00 is axially free relative to driving member 18. Although
illustrated as an external spline, it is contemplated that spline 118 can be an internal
10 spline or any other suitable mechanical input device.
Second drive member 104 includes a flange 122. Flange 122 has a fastener
pattern 124 configured connecting flexible coupling I 00 to a driven member 20 (shown
in Fig. 1) such that flexible coupling 100 is fixed both axially and in rotation relative to
driven member 20. lt is contemplated that fastener pattern 124 of flange 122 cooperate
15 with spline 118 to allow flexible coupling I 00 to be installed and/or removed from drive
train system 16 (shown in Fig. 1), installation and/or removal generally being facilitated
by the ability of flexure 108 to accommodate angular misalignment between first drive
member 102 andsecond drive member 104. Although described herein with a splined
first drive member and a flanged second drive member, it is to be understood and
20 appreciated that either or both of first drive member 102 and second drive member 104
can have splines and/or flanges, as suitable for an intended application. It is also to be
understood and appreciated that other connection arrangements can be employed to
fasten second drive member 104 to driving member 18 and first drive member 102 to
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driven member 20, including connections like welds that connect directly to a connecting
shaft, as suitable for an intended application.
Referring to Figs. 4 and 5, angular stop has a first position I and a second position
ll relative to second drive member I 04. In the first position, shown in Fig. 4, an outer
5 surface 146 of angular stop 116 is separated from an interior surface 148 of second drive
member 104 by radial gap 107, a width defined by radial gap 107 being substantially
uniform circumferentially about angular stop 116. In the second position II, shown in Fig.
5, outer surface 146 of angular stop 116 contacts interior surface 148 of second drive
member I 04, radial gap I 07 being circumferentially intetmpted at the contact location
I 0 disposed between angular stop 116 and interior surface 148 of second drive member I 04.
When axial mismatch between first drive member 102 and second drive member
l 04 is such that angular stop 116 is between first position land second position II, no
contact occurs between angular stop 116 and second drive member 104. This prevents
wear that would otherwise occur between the contacting surfaces within flexible coupling
15 100. When angular mismatch between first drive member 102 and second drive member
104 is such that angular stop 116 assumes position II, flexible coupling 100 is axially
limited, and further angular mismatch is discouraged (or prevented entirely) by angular
stop 116. This prevents deformation of flexure 108 beyond that imposed when angular
stop 116 is in position II. This allows limiting the maximum deformation imposed on
20 flexure 108 by the sizing selected for radial gap 107 while minimizing the contact
necessitated by the angular misalignment limiting feature of flexible coupling 100 to only
instances where the misalignment is such that angular stop 116 is in position II.
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With reference to Fig. 6, a flexible coupling 200 is shown. Flexible coupling 200
is similar to flexible coupling 100 and additionally includes a two-piece construction. In
this respect flexible coupling 200 includes a first drive member 202 and second drive
member 204 integrally formed with a portion of a flexure 208. In this respect first drive
5 member 202 extends axially between a spline 218 and an end of collar 216, and includes
a first diaphragm element 226. First diaphragm element 226 is integrally connected to a
seat 214 of first drive member 202 axially opposite spline 218, and extends
circumferentially about collar 216. Second drive member 204 extends axially between a
flange 222 and a second diaphragm element 228. Second diaphragm element 228 is
1 0 integrally connected to second drive member 204 on an end thereof axially opposite
flange 222. A single weld 243 couples first diaphragm member 226 with second
diaphragm member 228, second drive member 204 being couple therethrough to first
drive member 202.
It is contemplated that first drive member 202 and first diaphragm element 226 be
15 integral with one another, integral as used herein meaning beingjointless or weldless.
Jointless and/or weldless arrangements can be formed by removing material from the
interior and exterior of single piece of stock material using subtractive machining
operations. Jointless.and/or weldless arrangements can be formed using additive
manufacturing techniques, such as power bed fusion techniques. Such integral
20 construction has the advantage that the structure can be relatively light weight, there
being no need to add material to compensate for reduced load carrying capability in the
heat-affected zones generally formed in the vicinity of welds.
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Diaphragm couplings, e.g., first diaphragm element 226 (shown in Fig. 2) and
second diaphragm element 228 (shown in Fig. 2), can be used to reliably transmit torque,
e.g., torque T (shown in Fig. 1) along a load path while accommodating axial and/or
angular misalignment between driving and driven shafts, e.g., driving member 18 (shown
5 in Fig. I) and driven member 20 (shown in Fig. 1). The diaphragm coupling can be
arranged to rotate through a bend angle defined between the driving member and the
driven member, the diaphragm coupling having geometry arranged to distribute the stress
associated with the transmitted torque according to predetermined amount of bending.
In some drive train systems, e.g., drive train system 16 (shown in Fig. 1), it can be
I 0 necessary to limit the amount of angular misalignment accommodated by the diaphragm
coupling. In embodiments of flexible couplings described herein, angular misalignment
is limited by an angular stop fixed within the interior of one of the drive members and
extending through the diaphragm coupling and into the other of the drive members. In
certain embodiments, the angular stop is separated from an interior surface of the drive
15 member within which it is seated by a radial gap such a seat of the drive member axially
overlaps and is radially separated from the angular stop.
In the certain embodiments, the angular stop can have a first position wherein the
angular stop is separated from the first member by an annular gap defined between the
angular stop and the first member, the separation allowing the flexible coupling to
20 accommodate angular misalignment while bending without mechanical contact (and
associated wear) between the angular stop and the first member.
In accordance with certain embodiments, the angular stop can have first and
second position within the interior of the second drive member. In the first position the
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angular stop can be separated from the second drive member, and the flexible coupling
can be angularly unlimited. In the second position the angular stop can contact an
interior surface of the second drive member, the flexible coupling being angularly limited
by the contact between the angular stop and the interior of the second drive member. The
5 contact limits the angular misalignment (and bending) of imposed on the diaphragm
coupling, limiting stress while transmitting torque between the driving member and the
second member. It is also contemplated that the contact prevent overstress of the flexible
coupling during installation and removal, error-proofing the assembly process used to
interconnect the flexible coupling between the driving and driven members of the drive
I 0 train systems.
The methods and systems of the present disclosure, as described above and shown
in the drawings, provide for flexible couplings with superior properties including
structures for limiting coupling bending during coupling installation, coupling removal,
and while transmitting torque between the coupling input and first members. While the
15 apparatus and methods ofthe subject disclosure have been shown and described with
reference to preferred embodiments, those skilled in the art will readily appreciate that
changes and/or modifications may be made thereto without departing from the scope of
the subject disclosure.

What is claimed is:
I. A flexible coupling, comprising:
a flexure;
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a tirst drive member defining an axis and connected to the flexure;
a second drive member defining an axis and connected to the flexure on a side
of the flexure opposite the first drive member; and
an angular stop fixed within the first drive member and extending through at
least a portion of the second drive member,
wherein the angular stop is arranged to limit angular misalignment of the first
10 drive member axis relative to the second drive member axis while transmitting torque
between the first and second drive members.
2. The flexible coupling as recited in claim I, wherein an open through-bore extends
through the first drive member, the flexure, and the second drive member.
15
3. The flexible coupling as recited in claim 2, wherein the through-bore tapers
between a first width and a second width, the first width defined on a side of the angular
stop opposite the flexure, the second width defined within the angular stop, the second
width being smaller than the first width.
20
4. The flexible coupling as recited in claim l, wherein the first drive member
includes a seat, the seat axially overlapping the angular stop and being radially separated
from the angular stop by an annular gap.
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5. The flexible coupling as recited in claim 4, wherein the seat connects the annular
stop to the flexure.
6. The flexible coupling as recited in claim 1, wherein the first drive member is
coupled to the second drive member by a weld.
7. The flexible coupling as recited in claim 6, wherein the weld is disposed between
the first drive member and the flexure.
8. The flexible coupling as recited in claim 6, wherein the weld is disposed between
the second drive member and the flexure.
9. The flexible coupling as recited in claim 6, wherein the weld is disposed within
15 the flexure.
I 0. The flexible coupling as recited in claim 6, wherein a single weld connects the
first drive membeLto.thesecond drive member.
20 11. The flexible coupling as recited in claim I, wherein the flexure comprises a first
diaphragm element integrally connected to the first drive member and a second
diaphragm element integrally connected to the second drive member, the first diaphragm
element being coupled to the second diaphragm element by a weld.
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12. The flexible coupling as recited in claim II, wherein the first diaphragm element
is connected to the first drive member at an i1mer hub of the first diaphragm element.
13. The flexible coupling as recited in claim II, wherein the second diaphragm
5 element is connected to the second drive member at an inner hub of the second
diaphragm element.
14. The flexible coupling as recited in claim 11, wherein an outer rim ofthe first
diaphragm element is connected to an outer rim of the second diaphragm element.
10
15. The flexible coupling as recited in claim 1, further comprising a spline disposed
on one of the first and second drive members and a flange with a fastener pattern
disposed on the other of the first and second drive members.
15 16. A drive train system, comprising:
a flexible coupling as recited in claim 1;
a drive member connected to the first drive member; and
a driven member connected to the second drive member,
wherein the angular stop has a first position and a second position, the angular
20 stop being radially separated from the second drive member in the first position, the
angular stop contacting the second drive member in the second position.