Note: Descriptions are shown in the official language in which they were submitted.
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1
A mounting arrangement for mounting a gear box of a rotorcraft to a
fuselage of a rotorcraft
The invention is related to a mounting arrangement for mounting
at least a gear box of a rotorcraft to a fuselage of a rotorcraft. The
invention is further related to a rotorcraft comprising such a mounting
arrangement.
Lift and other forces that are required in order to allow a
controlled flight of a rotorcraft are usually at least essentially
generated through one or more rotors of the rotorcraft in a more or
less horizontal plane. Conventional design methodology utilizes a
rotating or non-rotating mast, to which a given rotor that is powered
by an associated gear box of the rotorcraft is mounted and which is
usually connected to a gear box independent support structure. The
latter is sometimes also referred to as a stand pipe support structure
or a lift housing, which is connected to the rotorcraft's airframe, i. e.
the rotorcraft's fuselage. Alternatively, the rotating or non-rotating
mast can be connected to a mast mounting integrated into the
associated gear box, which in turn is connected to the airframe of the
rotorcraft. Furthermore, some designs may feature load paths,
wherein forces in one or more load directions are solely carried by the
gear box independent support structure, while all other forces are
routed through the gear box.
It should be noted that in the context of the present invention all
arrangements where all bearings that transmit non-torque rotor forces
and moments from rotating elements to static elements are mounted
above gears of a given gear box of a rotorcraft are considered as
having a gear box independent support structure, even if the latter is
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integrated into a part of a respective gear box housing. A respectively
selected design is usually merely dependent on an underlying
rotorcraft layout and other applicable factors. Such factors e. g.
comprise a selected height above the airframe of the rotorcraft that
the gear box and gear box independent support structure impose on
the rotor and it is generally considered that any rotor height above a
given height that is necessary to accommodate movement and
deformation of the rotor in relation to the airframe adds unnecessary
aerodynamic drag.
In operation of a rotor of a rotorcraft, large magnitude forces
and moments are generated and acting on the rotor that is powered
by an associated gear box. It is commonly known that the highest
magnitude forces generated by the rotor are those perpendicular to
an associated rotor plane, i. e. lift forces. The moments of highest
magnitude generated by the rotor are oriented around an axis running
on the associated rotor plane. Such large magnitude forces and
moments must be transferred to the airframe of the rotorcraft in order
to achieve a controlled flight of the rotorcraft while guaranteeing a
safe, reliable and durable operation. Furthermore, conversion of
rotation speed and torque in the associated gear box also generates
loads that must be transferred to the airframe of the rotorcraft.
Moreover, inertial loads generated by the associated gear box during
landing maneuvers or crash landings of the rotorcraft must also be
carried by the airframe.
Frequently, the gear box and the rotor of the rotorcraft are
mounted to its airframe by means of a single, i. e. collective mounting
arrangement. Furthermore, a variety of anti-vibration functions can be
achieved in the form of vibration isolation means that are arranged
between the gear box/mounting arrangement and the airframe in order
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to diminish lifetime reducing vibration loading on rotorcraft equipment
and in order to meet ever increasing customer requirements and state
regulations concerning safe working environments. In other words,
the gear box/rotor is mostly mounted to the airframe by an associated
mounting arrangement that is suitable for accommodating anti-
vibration means mounted between the gear box/rotor and the
airframe.
It should be noted that, as with all elements of a rotorcraft, a
lightweight design of such a mounting arrangement is of utmost
importance. It is obvious that a favorable selection of geometry and
material for all components of the mounting arrangement is therefore
of essence. Furthermore, it is generally considered that a compact
design is of low weight due to minimization of load carrying distances.
Furthermore, a cost efficient solution is generally preferred in order to
achieve commercial viability.
More specifically, conventional gear box designs generally use
a cast metal or machined metal housing for mounting of the gear box
and for transferring rotor loads that are occurring in operation. The
metals used are mainly aluminum and magnesium. Such cast metals
are, however, of comparatively low strength and have comparatively
high defect ratios that must be taken into consideration, and are
therefore comparatively heavy compared to machined metals.
Machining, on the other hand, places higher restrictions on a possible
gear box housing geometry, while allowing slightly higher stress
levels. Both methods have a limit on how thin geometries can be
manufactured.
Furthermore, structures of gear box housings are usually
adapted for separating their interior from the exterior. Therefore, such
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structures are oversized regarding stress levels as a consequence of
an underlying minimum thickness restriction due to cost or
manufacturing technology. Use of heavier materials with a higher
strength to weight ratio is, therefore, not beneficial as further
reduction of the wall thickness of the wall of the gear box housings is
not possible and, consequently, a large weight penalty is accumulated
in low stress regions. A combination of a lightweight material cast or
machined housing with a high strength mounting means is, therefore,
preferable. On the other hand any existing structure oversized for
stress should be used as far as possible instead of adding additional
elements. As composite materials are known for their high strength to
weight ratio and as they exhibit comparatively good fatigue
characteristics, it is common engineering practice to utilize these
materials in rotorcraft design.
Another issue that should be considered in the design of a
suitable mounting arrangement is that aside from connecting driving
elements of a given rotorcraft with its lift generating rotor, the gear
box is also used to drive various other devices and systems of the
rotorcraft. The weight and cost conscious integration of these devices
and systems is, thus, relevant for design of a suitable mounting
arrangement.
It should be noted that the term "mounting arrangement" refers
in the context of the present invention to all non-rotating elements
that are used to transfer rotor loads and potentially gear box loads to
the rotorcraft's airframe. Exemplary mounting arrangements are
described hereinafter.
The document EP 0 508 938 Al describes with respect to Figure
1B an exemplary mounting arrangement that comprises a stand pipe
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support structure for a main rotor assembly of a rotorcraft with a
plurality of attachment feet. This stand pipe support structure
supports a non-rotating rotor mast and a gear box of the main rotor
assembly of the rotorcraft, which are integrated with an attachment
5
collar of the stand pipe support structure. In this type of stand pipe
support structure, a gear box housing of the main rotor assembly is at
least partly defined by a body of the stand pipe support structure,
including the attachment feet. The non-rotating rotor mast is
integrated with the attachment collar. The stand pipe support
structure is secured to an upper deck region of the rotorcraft by
means of bolts passing through the attachment feet. Dynamic and
static loads of the main rotor assembly are transmitted to a single
load transfer level of the rotorcraft's airframe, i. e. the upper deck
region, via the attachment feet.
This stand pipe support structure can be manufactured
comparatively easily and with low costs of fabrication as an integral
unit, and can easily be mounted to an upper deck region of a
rotorcraft. Furthermore, due to a relatively uncluttered configuration
of this stand pipe support structure, hydraulic lines, subsystem wiring
and other interfacing elements that are typically routed over the upper
deck region may be readily run over/adjacent to an exterior surface of
the stand pipe support structure.
However, this stand pipe support structure is disadvantageous
with respect to integration of the gear box within the stand pipe
support structure, as the gear box housing acts as a structural
member through which dynamic and static loads of the main rotor
assembly are intermediately transmitted. Moreover, the weight of the
stand pipe support structure is comparatively large because of a
required high structural strength of the stand pipe support structure
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and a usually low strength of the used materials. Furthermore, the
direct attachment of the gear box housing to the upper deck region
does not provide significant room for provision of a suitable anti-
vibration device.
The document EP 0 508 938 Al also describes with respect to
Figure 1C a further exemplary mounting arrangement that comprises
a strut support structure for a main rotor assembly of a rotorcraft.
This strut support structure is embodied as a high profile
configuration with an integration member and a plurality of struts,
such as cylindrical rods or machined legs extending from the
integration member and terminating in attachment feet. In this strut
support structure, a non-rotating rotor mast of the main rotor
assembly is attached to the integration member in a manner that is
similar to the one described above with respect to the stand pipe
support structure. However, the gear box, i. e. its gear box housing,
is attached in suspended combination to an underside of the
integration member and, consequently, is not part of a load path for
transfer of dynamic and static loads of the main rotor assembly.
Instead, the attachment feet are utilized to secure the strut support
structure to the rotorcraft's airframe and to transfer dynamic and
static loads of the main rotor assembly to respective hard points on
the airframe.
The main advantage of such a mounting arrangement
concerning load path and material optimization is the possibility of
utilizing a high strength to weight ratio material in the strut support
structure and the plurality of struts due to not being bound by
respective requirements of gear box design. However, a required
minimum wall thickness of the gear box housing combined with it not
being used for loads transfer results in comparatively low stress
CA 02952491 2016-12-20
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levels and, consequently, wasted material and weight. Furthermore,
routing of hydraulic lines, electrical subsystem wiring and other
interface components along a respective upper deck region of the
rotorcraft is complicated because of the strut network that must be
accommodated thereon. Finally, an anti-vibration device can easily be
integrated into the struts of the strut support structure, but due to a
comparatively large number of struts, this would be costly and weight
intensive.
The document US 2007/0034736 Al describes another
exemplary mounting arrangement that comprises a strut support
structure for a main rotor assembly of a rotorcraft. This strut support
structure reduces the underlying number of struts required for load
transfer in comparison to the above described strut support structure
by utilizing a support arrangement below the gear box for loads
running approximately parallel to a rotor plane of the main rotor
assembly. More specifically, rotor and gear box of the main rotor
assembly are held along the rotor axis by four angled struts that are
connected to a lift housing atop the gear box. The lift carrying bearing
in this design is situated at the top of the lift housing where the struts
are attached. Due to the offset of respective strut attachments to the
rotor axis, a part of the moments generated in the main rotor
assembly's rotor mast by the rotor are absorbed by the struts as well,
but this results in large forces in the struts. However, the strut
support structure is not suited for transferring torque loads parallel to
the rotor plane, as the struts are situated more or less radial to the
rotor axis. Such torque loads and remaining moments are, therefore,
countered by the support arrangement below the gear box, which is
designed in order to allow vertical freedom of movement, but no
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rotation around the rotor axis. Movement perpendicular to the rotor
axis may be allowed for accommodating an anti-vibration function.
An example of a device that is suitable for allowing such a
perpendicular movement is described in the document US 3,920,202.
Another option is the use of a membrane.
The mounting arrangement according to document US
2007/0034736 Al is simple and comprises only a few constituent
components with comparatively small complexity. Furthermore, its
struts can easily be adapted to end on strong structural elements of
the rotorcraft's airframe, such as intersections of longerons and
frames. Moreover, an anti-vibration device can easily be mounted
below the gear box, if desired. Otherwise, a simple and cheap strut
arrangement can be achieved. Alternatively, an anti-vibration device
can be fitted into the angled struts as well.
However, due to the effects of the strut geometry, flat struts
would result in high strut loads and, therefore, require heavy and
large struts. This can be avoided by utilizing a high height and low
diameter gear box or by adding an additional support structure above
the gear box, which would, nevertheless, lead to a bulky and
cumbersome design. Additionally, this height requirement may conflict
with a need for a low mounted rotor that is required for optimized
aerodynamics.
Still another mounting arrangement is known from the Airbus
Helicopters rotorcraft H135. This mounting arrangement comprises a
rotating rotor mast and a gear box housing that consists of an upper
and a lower housing. Suitable bearings for bearing the rotor mast in a
rotatable manner are integrated into the upper and lower housings.
The upper housing furthermore comprises, at two opposing sides,
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attachment structures that are integrally formed with the upper
housing for attachment of so-called z-struts, which are adapted for
transfer of lift forces. So-called x-struts, which are adapted for
transfer of torque and in-plane rotor forces, are connected to bottom
parts of the triangular attachment structures and a so-called y-strut,
which is adapted for transfer of in-plane rotor forces, is attached to a
separate bracket on the lower housing. The gearbox housing
comprises dimensions that are chosen such that all required gear box
internals can be installed therein. Consequently, these dimensions
also define a minimum distance between the two triangular
attachment structures, which can be larger than required for the struts
or a possible anti-vibration device. At the same time, a possible
choice of gear box materials is hindered by the minimum wall
thickness issue of the gear box housing.
Advantageously, this mounting arrangement is comparatively
flat and utilizes the required minimum wall thickness of the gear box
housing to its advantage, as it carries rotor loads. However, if the
distance between the two triangular attachment structures is larger
than required for the struts, this results in unnecessary long load
paths and induces a weight penalty, i. e. an unnecessary large gear
box weight.
Still another mounting arrangement is known from the Airbus
Helicopters rotorcraft H145. This mounting arrangement also
comprises a rotating rotor mast and a gear box housing that consists
of an upper and a lower housing, wherein suitable bearings for
mounting the rotor mast in a rotatable manner are integrated into the
upper and lower housings. However, in contrast to the above
described mounting arrangement that is known from the Airbus
Helicopters rotorcraft H135, four V-shaped brackets are attached to
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the upper and lower housings for transferring the lift forces. The V-
shaped brackets are attached to the rotorcraft's airframe with struts
and connected to the gear box housing by means of screws. This
screw connection is, however, not directly adjacent to the bearings for
5 the rotor mast. Furthermore, additional struts are provided at the
bottom of the gear box housing for transferring the torque and drag
loads.
Advantageously, this mounting arrangement allows parts of the
strut support structure to be made of a material other than that used
10 for the gear box housing thereby utilizing optimized material
selection. Furthermore, due to the differential nature of the design of
the mounting arrangement, an underlying placement of the struts is
less constraint by the gear box internals and the gear box housing.
However, due to geometrical constraints, the V-shaped brackets are
not mounted at a respective source of the loads that are introduced in
operation of the rotorcraft into the gear box housing, namely at the
upper and lower mast bearings. The gear box housing, therefore, has
to carry all loads between the V-shaped brackets and the bearings for
the rotor mast for a distance. Furthermore, the attachment of the V-
shaped brackets with close set screws lead to a stress concentration
in the gear box at corresponding positions of the screw connections.
It is, therefore, an object of the present invention to provide a
new mounting arrangement for mounting at least a gear box and/or
rotor of a rotorcraft to an airframe of a rotorcraft with improved space
and weight efficiency.
This object is solved by a mounting arrangement for mounting at
least a gear box of a rotorcraft to a fuselage of a rotorcraft.
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More specifically, according to the present invention, the
mounting arrangement comprises a gear box of a rotorcraft and at
least two support plates that are rigidly attached to at least
approximately opposing sides of the gear box. Each one of the at
least two support plates comprises at least two attachment means
that are adapted to allow attachment of the at least two support plates
to a fuselage of a rotorcraft by means of associated struts in order to
enable transfer of induced loads occurring in operation, which are
directed into a predetermined load direction, via the associated
.. struts.
It should be noted that in the context of the present invention
the terms "fuselage" and "airframe" are interchangeably used for
designating a load supporting structure of a rotorcraft, to which the
inventive mounting arrangement is rigidly attached. Furthermore, it
should be noted that the present invention is only described by way of
example with respect to a rotorcraft, but can likewise by applied at
least to other aircrafts, where a given component must be connected
to a load supporting structure such that induced loads can be
transferred from the given component to the load supporting
structure.
Advantageously, the inventive mounting arrangement provides
an improved strut arrangement compared to conventional designs.
Furthermore, a weight amelioration can be achieved due to use of
manufacturing characteristics of known gear box designs concerning
minimum wall thickness requirements, in order to provide a mounting
arrangement with reduced material quantity and, thus, reduced
weight. A further weight reduction is possible due to the differential
design of the inventive mounting arrangement allowing improved
material use.
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According to one aspect of the present invention, the support
plates are embodied as continuous, complete plates, i. e. plates
without any openings or cut-outs through which parts of the gear box
could protrude. In this case, the support plates can be used as a gear
box support that is merely adapted for connecting the gear box, i. e.
an associated gear box housing, to the associated struts, if the
associated gear box housing is self-contained. Otherwise, it can
further be used to cover or close lateral openings that are provided in
the associated gear box housing.
According to another aspect of the present invention, the
support plates comprise openings or cut-outs through which parts of
the gear box may protrude. In this case, the support plates can be
used as a gear box support that is merely adapted for connecting the
gear box, i. e. the associated gear box housing to the associated
struts, if the associated gear box housing is self-contained and
protrudes through the openings or cut-outs. Otherwise, gears of the
gear box may protrude through the openings or cut-outs, so that the
associated gear box housing and the support plates define an
uncomplete containment surface with open regions. In this case, the
support plates can be provided with covers for covering these open
regions or, alternatively, additional equipment such as an accessory
drive gear box can be used to cover the open regions.
Preferably, the support plates are manufactured using
composite material. More generally, the support plates preferentially
comprise fiber reinforced polymers. For these materials it may be
necessary to provide the interface between the gearbox housing and
the support plates with a thermal insulation means so as to prevent
localized extreme heat, such as heat that develops in a bearing
during loss-of-oil scenarios, from damaging the composite material.
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The need for such insulation means is dependent on the proximity of
the carbon to such localized hot spots and the heat dissipating
properties of the gearbox housing. Alternatively, the support plates
may comprise or be made of a suitable metal, such as e. g. titanium
or titanium alloy.
According to one aspect of the present invention, the support
plates are not only adapted to enable transfer of induced loads
occurring in operation, which are directed into a single predetermined
load direction, but also transfer of induced loads occurring in
operation, which are directed into another load direction. Preferably,
the support plates are at least adapted to enable transfer of lift loads
and/or torque and/or drag loads.
According to a preferred embodiment, the at least two support
plates are at least approximately arranged in parallel to each other.
According to a further preferred embodiment, the gear box
comprises a housing. The housing defines at least partly a
containment surface of the gear box and the at least two support
plates are rigidly attached to the housing by means of associated
attachment members.
According to a further preferred embodiment, the at least two
support plates define at least partly the containment surface of the
gear box.
According to a further preferred embodiment, the associated
attachment members comprise bolts, screws and/or rivets.
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According to a further preferred embodiment, at least one of the
at least two support plates comprises an opening. The housing
protrudes at least partly through the opening.
According to a further preferred embodiment, at least one of the
at least two support plates comprises an opening. The gear box is
adapted for accommodating a plurality of gears. At least one of the
plurality of gears protrudes at least partly through the opening.
According to a further preferred embodiment, at least one
closing element is provided for closing the opening.
According to a further preferred embodiment, each one of the at
least two support plates comprises at least one additional attachment
means that is adapted to allow attachment of the at least two support
plates to a fuselage of a rotorcraft by means of an associated strut in
order to enable transfer of induced loads occurring in operation,
which are directed into a further load direction, via the associated
strut. The further load direction differs from the predetermined load
direction.
According to a further preferred embodiment, the gear box
comprises bearings for mounting a rotor mast of a rotor of a rotorcraft
in a rotatable manner. The predetermined load direction is at least
oriented either in parallel to a longitudinal extension of the rotor mast
or upright on a fuselage of a rotorcraft within a range of variation of
approximately 5 .
According to a further preferred embodiment, the further load
direction is at least approximately perpendicular to the predetermined
load direction.
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CA 02952491 2016-12-20
According to a further preferred embodiment, at least one of the
at least two support plates comprises fiber reinforced polymers.
According to a further preferred embodiment, the associated
struts are adapted for reducing vibration occurring in operation.
5 According to a further preferred embodiment, the associated
struts are embodied as vibration dampers.
According to a further preferred embodiment, the gear box
comprises at least one additional attachment means that is adapted to
allow attachment of the gear box to a fuselage of a rotorcraft by
10 means of an associated strut in order to enable transfer of induced
loads occurring in operation, which are directed into a further load
direction, via the associated strut. The further load direction differs
from the predetermined load direction.
The present invention further provides a rotorcraft that
15 comprises a mounting arrangement according to the present
invention.
Preferred embodiments of the invention are outlined by way of
example in the following description with reference to the attached
drawings. In these attached drawings, identical or identically
functioning components and elements are labeled with identical
reference numbers and characters and are, consequently, only
described once in the following description.
- Figure 1 shows a lateral view of a helicopter with a rotor mast
and a rotor and gear box mounting arrangement according to the
invention,
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- Figure 2 shows a perspective view of the mounting
arrangement of Figure 1, which is embodied according to a first
embodiment,
- Figure 3 shows a perspective view of the mounting
arrangement of Figure 2 with the rotor mast of Figure 1,
- Figure 4 shows a perspective view of a support plate of the
mounting arrangement of Figure 2 and Figure 3,
- Figure 5 shows a perspective view of the mounting
arrangement of Figure 3 that is mounted to a fuselage of the
helicopter of Figure 1,
- Figure 6 shows a perspective view of a mounting arrangement
that is embodied according to a second embodiment and mounted to a
fuselage of the helicopter of Figure 1,
- Figure 7 shows a perspective view of a mounting arrangement
that is embodied according to a third embodiment and mounted to a
fuselage of the helicopter of Figure 1, and
- Figure 8 shows a perspective view of a mounting arrangement
that is embodied according to a fourth embodiment and mounted to a
fuselage of the helicopter of Figure 1.
Figure 1 shows an aircraft 1 that is exemplarily illustrated as a
rotorcraft and, in particular, as a helicopter. Thus, for purposes of
simplicity and clarity, the aircraft 1 is hereinafter referred to as the
"helicopter" 1. It should, however, be noted that the present invention
is not limited to helicopters and can likewise be applied to other
aircrafts, independent of a particular configuration thereof.
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Illustratively, the helicopter 1 comprises a fuselage 2 that is
connected to a landing gear if and defines a tail boom 2a and a cabin
2b. The helicopter 1 further preferably comprises at least one main
rotor la, which is illustratively embodied as a multi-blade main rotor,
for providing lift and forward, backward or sideward thrust during
operation. Therefore, the at least one multi-blade main rotor la is
powered in operation of the helicopter 1 by means of a main gear box
6 that is driven by associated engines and preferably mounted to the
fuselage 2 via an associated mounting arrangement 7. The at least
one multi-blade main rotor la exemplarily comprises a plurality of
rotor blades 1 b, lc that are mounted at an associated rotor head id
to a rotor mast le, which rotates in operation of the helicopter 1
around an associated rotor axis.
According to one aspect of the present invention, the associated
mounting arrangement 7 is at least adapted for transferring induced
loads occurring in operation of the helicopter 1, which are directed
into a first predetermined load direction 1j. Illustratively, this first
predetermined load direction lj corresponds to a height direction of
the helicopter 1, in which loads generated by lift forces are induced.
More specifically, the first predetermined load direction 1 j is
preferentially at least oriented either in parallel to a longitudinal
extension of the rotor mast le or upright on the fuselage 2 of the
helicopter 1 within a range of variation of approximately 5 .
Preferably, the associated mounting arrangement 7 is also
adapted for transferring induced loads occurring in operation of the
helicopter 1, which are directed into a second predetermined load
direction ii. By way of example, this second predetermined load
direction li differs from the first predetermined load direction 1 j and
corresponds to a longitudinal direction of the helicopter 1, in which
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loads generated by drag forces and gearbox torque are induced.
Illustratively, the second predetermined load direction 1i is at least
approximately perpendicular to the first predetermined load direction
1j.
It should be noted that the at least one multi-blade main rotor
la is preferably mounted to the helicopter 1 through the main gear
box 6. Thus, according to one aspect of the present invention not only
the main gear box 6, but also the at least one multi-blade main rotor
la is mounted to the fuselage 2 by means of the mounting
arrangement 7. The latter is, therefore, preferably adapted for
transferring not only gear box loads, but also rotor loads to the
fuselage 2.
By way of example, the helicopter 1 further comprises at least
one preferentially shrouded counter-torque device 3 configured to
provide counter-torque during operation, i. e. to counter the torque
created by rotation of the at least one multi-blade main rotor la for
purposes of balancing the helicopter 1 in terms of yaw. The at least
one counter-torque device 3 is illustratively provided at an aft section
of the tail boom 2a, which preferably further comprises a bumper 4
and a vertical stabilizer 5. Illustratively, the helicopter 1 is further
provided with a horizontal stabilizer 1k, which is exemplarily arranged
closed to the aft section of the tail boom 2a.
Figure 2 shows the mounting arrangement 7 of Figure 1, which
is at least adapted for mounting the gear box 6 of the helicopter 1 of
Figure 1 to the fuselage 2 of the helicopter 1. The gear box 6 is
preferably equipped with suitable rotor bearings 1g (and 1h in Fig. 3)
for bearing the rotor mast le of Figure 1 in a rotatable manner, so
that the rotor mast le of Figure 1 is mounted by means of the
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mounting arrangement 7 via the gear box 6 to the fuselage 2 of the
helicopter 1 of Figure 1. Illustratively, the rotor bearings 1g (and 1h in
Fig. 3) are embodied as antifriction bearings, in particular rolling-
element bearings.
Preferably, the gear box 6 comprises a housing 6a and a
plurality of input/output torque interfaces 6d. The housing 6a
preferentially consists of an upper housing 6b and a lower housing
6c. The upper housing 6b is preferably attached to the lower housing
6c by means of suitable attachment members (6f in Figure 3).
Illustratively, the housing 6a defines at least partly a
containment surface 6e, respectively a containment structure 6e, of
the gear box 6. This containment surface/structure 6e preferably
encompasses a plurality of gear box internal components, such as e.
g. a plurality of gears 9.
According to one aspect of the present invention, the mounting
arrangement 7 comprises at least the gear box 6 and at least two, and
exemplarily exactly two, support plates 8. The latter are preferably
rigidly attached to at least approximately opposing sides of the gear
box 6 and, preferentially, at least approximately arranged in parallel
to each other with a predefined offset 8e. At least one of the two
support plates 8 preferably comprises fiber reinforced polymers
and/or metal.
The two support plates 8, which are embodied as gear box
independent components, are preferably attached to the housing 6a
of the gear box 6 by means of associated attachment members 8a
and may define at least partly the containment surface/structure 6e of
the gear box 6. By way of example, the associated attachment
members 8a comprise bolts, screws and/or rivets.
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= CA 02952491 2016-12-20
Illustratively, each one of the two support plates 8 comprises a
gear box attachment region 8b, where the respective support plate 8
is attached to the housing 6a of the gear box 6. According to one
aspect of the present invention, this gear box attachment region 8b
5 comprises an opening 8f, which is exemplarily provided as a cut-out
in the support plate 8. Thus, a gear 9 of the gear box 6 that is at least
partly accommodated inside the housing 6a may at least partly
protrude through the opening 8f.
More specifically, the gear box 6 is preferably adapted for
10 accommodating a plurality of gears 9 and at least one of this plurality
of gears 9 protrudes at least partly through the opening 8f. However,
it should be noted that constitution and structure of a gear box and its
internals are well-known to the person skilled in the art and, as such,
not part of the present invention. Therefore, they are not described in
15 greater detail hereinafter.
According to one aspect of the present invention, each one of
the two support plates 8 comprises at least two attachment means 8c
that are adapted to allow attachment of the respective support plate 8
to the fuselage 2 of the helicopter 1 of Figure 1 as described below
20 with reference to Figure 5 up to Figure 7. Preferably, each one of the
two support plates 8 comprises at least one further attachment means
8d that is also adapted to allow attachment of the respective support
plate 8 to the fuselage 2 of the helicopter 1 of Figure 1, as described
below with reference to Figure 5 up to Figure 7. Illustratively, the
attachment means 8c, 8d are embodied as reinforced openings and
adapted for transfer of loads that are induced from different load
directions, i. e. the load directions 1j, 1i of Figure 1. The load
directions being preferably approximately in plane of the support plate
8.
1
I
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Figure 3 shows the mounting arrangement 7 of Figure 2 with the
rotor mast le of Figure 1. Figure 3 further illustrates bearing of the
rotor mast le at least in the rotor bearing 1g of Figure 2, which is
illustratively arranged in the upper housing 6b of the gear box 6, and
in a rotor bearing 1h, which is illustratively arranged in the lower
housing 6c of the gear box 6.
Figure 3 also further illustrates the rigid attachment of the
support plates 8 at the housing 6a of the gear box 6 in the respective
gear box attachment regions 8b by means of the attachment members
8a. Illustratively, the latter are embodied as bolts.
Figure 4 shows one of the support plates 8 of Figure 2 and
Figure 3 in greater detail. Figure 4 further illustrates the gear box
attachment region 8b with the opening 8f in the form of a cut-out, as
well as the attachment means 8c, 8d.
According to one aspect of the present invention, the support
plate 8 is at least approximately triangular. By way of example, the
triangular support plate 8 is provided with a longer base side, where
the attachment means 8c are arranged, and a tip that is opposed to
said longer base side, and where the attachment means 8d is
arranged.
Figure 5 shows an exemplary assembly 10 with the mounting
arrangement 7 of Figure 2 and Figure 3, which is mounted to the
fuselage 2 of the helicopter 1 of Figure 1 via associated struts 1 la,
11 b, 1 lc. Preferably, at least each one of the associated struts 1 la,
lib comprises clevises lid, which are adapted to enable attachment
of the associated struts 1 la, 11 b to the attachment means 8c, 8d of
the support plates 8, and to corresponding mounting points provided
at the fuselage 2. The attachment is preferentially performed by
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means of fixation bolts lie. However, other attachment members are
likewise contemplated and within the common knowledge of the
person skilled in the art. The associated struts 11c are preferably
attached to attachment means that are provided at a lower side of the
lower housing 6c of the gear box 6.
According to one aspect of the present invention, the
attachment means 8c are adapted to enable transfer of induced loads
occurring in operation of the helicopter 1 of Figure 1, which are
directed into the predetermined load direction 1 j of Figure 1, via the
associated struts 11a. Likewise, the attachment means 8d are
adapted to enable transfer of induced loads occurring in operation of
the helicopter 1 of Figure 1, which are directed into the predetermined
load direction li of Figure 1, via the associated struts 11 b.
Figure 6 shows the assembly 10 of Figure 5, which is according
to one aspect of the present invention equipped with one or more
closing elements 12. The latter are preferably adapted for closing the
openings 8f provided in the support plates 8 and, by way of example,
embodied as covers. Thus, the covers 12 define at least partly the
containment surface/structure 6e of the gear box 6.
However, it should be noted that such covers are only described
and illustrated by way of example and not for limiting the present
invention accordingly. Instead, any element that is suitable for closing
the opening 8f is likewise contemplated, such as e. g. an accessory
drive gear box and so on.
Figure 7 shows the assembly 10 of Figure 5, wherein the upper
housing 6b and the lower housing 6c of the housing 6a of the gear
box 6 are respectively provided with associated upper housing end
sections 13a and lower housing end sections 13b in regions, where
CA 02952491 2016-12-20
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the housing 6a is rigidly attached to the support plates 8. In this case,
the housing 6a itself is self-contained and protrudes at least partly
through the opening 8f provided in the support plates 8 by means of
the end sections 13a, 13b, which define at least partly the
containment surface/structure 6e of the gear box 6. Consequently, the
support plates 8 do not contribute to the definition of the containment
surface/structure 6e of the gear box 6 in this case.
Figure 8 shows the assembly 10 of Figure 5, wherein according
to one aspect of the present invention the mounting arrangement 7 is
equipped with at least one and, illustratively two alternative support
plates 14 instead of the support plates 8 of Figure 2 to Figure 7. In
contrast to the support plates 8, the alternative support plates 14 are
not provided with the opening, i. e. cut-out 8f of Figure 2 to Figure 7
in their gear box attachment region 8b. Instead, they are embodied as
continuous, complete plates. A cut-out may nevertheless be
advantageous in certain applications and may be implemented as
shown in Figure 2 up to Figure 7 with the embodiments using the
support plates 8. Furthermore, in contrast to the support plates 8, the
alternative support plates 14 are only provided with the attachment
means 8c, while the attachment means 8d are replaced by means of
attachment means 6g, which are provided at the lower housing 6c of
the housing 6a of the gear box 6.
Similar to the support plates 8, the alternative support plates 14
are adapted for mounting the gear box 6 of the helicopter 1 of Figure
1 to the fuselage 2 of the helicopter 1. However, in the case
described above with reference to Figure 2, where the housing 6a of
the gear box 6 is open at its sides, the alternative support plates 14
close the gear box 6 and, thus, define part of its containment
surface/structure 6e.
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It should be noted that modifications to the above described
embodiments are within the common knowledge of the person skilled
in the art and, thus, also considered as being part of the present
invention. For instance, the associated struts 11a, 11b, 11c of Figure
5 to Figure 8 can be adapted for reducing vibration occurring in
operation of the helicopter 1 of Figure 1. According to one aspect of
the present invention, they can also be embodied as vibration
dampers. Exemplary anti-vibration devices are described in the
document US 6,293,532 B2.
Furthermore, the above described aspects of the present
invention can similarly be applied, i. e. combined to define variants of
the present invention. For instance, the gear box 6 of Figure 1 can be
open on one side, as described above with reference to Figure 2 and
Figure 3, and closed on the other side, as described above with
reference to Figure 7, or a cover can be provided on one side, as
described above with reference to Figure 6. Alternatively, one side of
the mounting arrangement 7 of Figure 1 can be embodied by the
support plate 8 of Figure 2 to Figure 7, and the other side with the
alternative support plate 14 of Figure 8, and so on.
CA 02952491 2016-12-20
Reference List
1 aircraft
la multi-blade main rotor
1 b, 1 c rotor blades
5 id rotor head
le rotor mast
if landing gear
1g, lh rotor bearings
ii longitudinal direction
10 1 j height direction
1k horizontal stabilizer
2 fuselage
2a tail boom
2b cabin
15 3 counter-torque device
4 bumper
5 vertical stabilizer
6 main gear box
6a main gear box housing
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6b upper housing
6c lower housing
6d input/output torque interfaces
6e containment surface/structure
6f upper/lower housing attachment members
6g lower housing second direction force transmitting
attachment means
7 rotor and gear box mounting arrangement
8 support plates
8a support plate attachment members
8b main gear box attachment region
8c first direction force transmitting attachment means
8d second direction force transmitting attachment means
8e plate offset
8f plate opening
9 gears
10 fuselage with rotor and gear box mounting assembly
1 1a first direction force transmitting strut
11 b second direction force transmitting strut
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1 1 c third direction force transmitting strut
11d clevises
11e fixation bolts
12 plate opening closing element
13a upper housing end section
13b lower housing end section
14 alternative support plates
