U.S. patent application number 13/578096 was filed with the patent office on 2013-06-27 for landing gear with steerable axle.
This patent application is currently assigned to MESSIER-DOWTY LTD. The applicant listed for this patent is Ian BENNETT, Robert MENEZES, Paul SHAW. Invention is credited to Ian BENNETT, Robert MENEZES, Paul SHAW.
Application Number | 20130161445 13/578096 |
Document ID | / |
Family ID | 42827390 |
Filed Date | 2013-06-27 |
United States Patent
Application |
20130161445 |
Kind Code |
A2 |
BENNETT; Ian ; et
al. |
June 27, 2013 |
LANDING GEAR WITH STEERABLE AXLE
Abstract
There is described a landing gear having a bogie including a
elongated beam (2) for accommodating at least two axles receiving
each a pair of ground engaging wheels, at least one axle (5) being
pivotally mounted on the elongated beam. The landing gear further
includes axle travel limitation means (10) extending between said
pivotable axle and said elongated beam to be hitched up thereto,
said travel limitation means being deformable one way starting from
an stable and lockable state thereof corresponding to a landing
position of said pivotable axle. There are also described
independently lockable and actuatable telescopic struts.
Inventors: |
BENNETT; Ian;
(Gloucestershire, GB) ; MENEZES; Robert;
(Gloucestershire, GB) ; SHAW; Paul;
(Gloucestershire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BENNETT; Ian
MENEZES; Robert
SHAW; Paul |
Gloucestershire
Gloucestershire
Gloucestershire |
|
GB
GB
GB |
|
|
Assignee: |
MESSIER-DOWTY LTD
GLOUCESTER, GLOUCESTERSHIRE
GB
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20130020431 A1 |
January 24, 2013 |
|
|
Family ID: |
42827390 |
Appl. No.: |
13/578096 |
Filed: |
February 10, 2010 |
PCT Filed: |
February 10, 2010 |
PCT NO: |
PCT/GB201/000244 PCKC 00 |
371 Date: |
October 11, 2012 |
Current U.S.
Class: |
244/50;
244/102SS; 244/103R |
Current CPC
Class: |
B64C 2025/345 20130101;
B64C 25/48 20130101; B64C 25/50 20130101; B64C 25/34 20130101 |
Class at
Publication: |
244/50;
244/103.R; 244/102.SS |
International
Class: |
B64C 25/50 20060101
B64C025/50; B64C 25/10 20060101 B64C025/10; B64C 25/34 20060101
B64C025/34 |
Claims
1. A landing gear having a bogie including a elongated beam
(2;102;202;302) for accommodating at least two axles receiving each
a pair of ground engaging wheels, at least one axle (5;105;205;305)
being pivotally mounted on the elongated beam; characterized in
that the landing gear further includes axle travel limitation means
(10;110;210;310) extending between said pivotable axle and said
elongated beam to be hitched up thereto, said travel limitation
means being deformable one way starting from an stable and lockable
state thereof corresponding to a landing position of said pivotable
axle.
2. A landing gear according to claim 1, wherein said travel
limitation means (10) comprise a telescopic strut (11) having ends
articulated respectively to said pivotable axle and said elongated
beam, so that said stable lockable state corresponds to one of
fully extended or fully compressed configuration of said telescopic
strut, said telescopic strut having internal lock means for
automatically lock said telescopic in said stable state when
brought back thereto.
3. A landing gear according to claim 2, wherein said telescopic
strut (11;11') includes a piston rod received in a cylinder
(14;14') in a sliding relation and being hydraulically operable by
means of an extend port (20;20') and a shorten port (19;19'), said
telescopic strut further including internal locking means (25;25')
for locking said telescopic strut in one of fully extended or fully
compressed states, said locking means being hydraulically operable
between a locked and unlocked state by means of a lock port
(28;28') and an unlock port (27;27') that are independent from the
extend and shorten ports.
4. A landing gear according to claim 1, wherein said travel
limitation means (110;210;310) comprise two articulated members
(130/131; 230/231:330/331) having ends articulated respectively to
said pivotable axle and said elongated beam, so that said stable
lockable state corresponds to a substantially aligned configuration
of said members.
5. A landing gear according to claim 4, wherein said substantially
aligned configuration is defined by abutment means
(133/134;233/234;333/334) of said members that are arranged to come
in mutual engagement when said members are brought back to said
substantially aligned configuration.
6. A landing gear according to claim 4, further including a
steering actuator (135;235;335) engaging said members.
7. A landing gear according to claim 6, wherein said actuator
engages a knee (132;332) of said members.
8. A method of operating a landing gear according to claim 2,
comprising using the telescopic strut as a steering actuator.
9. A method of operating a landing gear according to claim 3,
comprising pressurizing said extend port is said telescopic strut
is locked in the fully extended state or said shorten port if the
telescopic strut is locked in the fully retracted state, before
pressurizing said unlock port, so as to offload the locking means
before unlocking.
10. A method of operating a landing gear according to claim 6,
comprising using the actuator as a lock means for maintaining said
members in the substantially aligned configuration.
11. A method of operating a landing gear according to claim 1,
comprising commanding some differential braking on the wheels
carried by said pivotable axle (5;105;205;305) to help or effect a
rotation of said pivotable axle back to said landing position.
12. A lockable and actuatable telescopic strut (11;11') intended
for use as a travel limitation means in a landing gear according to
claim 2, having a piston rod received in a cylinder in a sliding
relation and being hydraulically operable by means of an extend
port and a shorten port, said telescopic strut further including
internal locking means for locking said telescopic strut in one of
fully extended or fully compressed states, said locking means being
hydraulically operable between a locked and unlocked state by means
of an lock port and an unlock port that are independent from the
extend and shorten ports.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a National Stage of International
Application No. PCT/GB2010/000244 filed Feb. 10, 2010, the contents
of which are incorporated herein by reference in their entirety
PRIOR ART
[0002] Large aircraft are generally provided with multi-axle
landing gears having trucks or bogies carrying pairs of wheels.
Such bogies include an elongated beam supporting a plurality of
transversely extending axles, each axle carrying a pair of
wheels.
[0003] Some recent large aircraft are equipped with main landing
gears having six-wheels bogies with one rear pivotable axle so that
said axle and associated wheels can be steered in coordination with
steering of the nose landing gear wheels.
[0004] U.S. Pat. No. 5,242,131 assigned to BOEING illustrates axle
steering means having actuators arranged in a push-pull fashion.
U.S. Pat. No. 5,595,359 assigned to BOEING illustrates axle
steering means having one actuator arranged in a walking beam
fashion. U.S. Pat. No. 5,613,651 assigned to BOEING illustrates
axle steering means having one actuator extending between the bogie
and the axle and articulated thereto. These arrangements
accommodate a two-way steering so that the axle can be steered both
sides of a landing position in which the axle is brought back and
locked for take-off or landing.
[0005] To this end, the steering means are equipped with lock
means, such as center-lock means within the steering actuator as in
U.S. Pat. No. 5,613,651, or external locking means having a lock
supported by the bogie to engage a recessed portion of axle in the
landing position as in WO2006071262 to GOODRICH. However, such
locks will engage only if the axle is accurately brought back in
the landing position, which is difficult to achieve.
[0006] U.S. Pat. No. 2,943,820 teaches to mount an aft portion of
the bogie pivotable with respect to a fore portion of the bogie in
a one-way free-castoring relation when unlocked. The aft portion is
allowed to castor between a landing position where the aft portion
is aligned with the fore portion, and a one-way, maximum angled
position. When the aircraft turns, the aft portion of the bogie of
the inner landing passively pivots so as the tires of the rear
wheels do not scuff, whereas the aft portion of the bogie of the
outer landing gear remains in the landing position. However, the
articulation of the aft portion on the fore portion is highly
loaded and would be difficult to implement in case of a six-wheel
bogie with a center axle. Furthermore, having the aft portion
coming back to the landing position may require the pilot to
proceed to some S-turns before taking off, which may consume some
take-off runway length.
OBJECT OF THE INVENTION
[0007] It is an object of the invention to provide a bogied landing
gear with at least one steerable axle which is simpler that the
known landing gears.
BRIEF DESCRIPTION OF THE INVENTION
[0008] There is provided a landing gear having a bogie including a
elongated beam for accommodating at least two axles receiving each
a pair of ground engaging wheels, at least one axle being pivotally
mounted on the elongated beam. In accordance with the invention,
the landing gear further includes axle travel limitation means
extending between said pivotable axle and said elongated beam to be
hitched up thereto, said travel limitation means being deformable
one way starting from a stable and lockable state thereof
corresponding to a landing position of said pivotable axle.
[0009] Thus, the axle landing position is simply defined by the
stable state of the travel limitation means. This implies that the
axle may only be castored one way. Therefore, locking the pivotable
axle in the locking position is simply achieved by bringing the
axle back to the landing position until the travel limitation means
reaches its stable state, where it can be made to automatically
lock so as to lock the axle into the landing position. This locked
state corresponds to and end-of-stroke position, which makes it
much easier to lock compared to any intermediate locking
configuration.
[0010] In accordance with one particular embodiment of the
invention, said travel limitation means comprise a telescopic strut
having ends articulated respectively to said pivotable axle and
said elongated beam, so that the first stable lockable state
corresponds to one of fully extended or fully compressed
configuration of said telescopic strut. This telescopic strut may
also serve as a steering actuator.
[0011] In accordance with another particular embodiment of the
invention, said travel limitation means comprise two members
articulated to each other and having ends articulated respectively
to said pivotable axle and said elongated beam so that the stable
lockable state corresponds to a substantially aligned configuration
of said members.
BRIEF DESCRIPTION OF THE FIGURES
[0012] The invention will be better understood in the light of the
description of several embodiment, in reference to the following
figures:
[0013] FIGS. 1A and 1B are top views of a bogie of a landing gear
equipped with a rear pivotable axle according to a first particular
embodiment of the invention, illustrated in landing position and in
some angled position, respectively;
[0014] FIG. 2A is a sectional view of one particular embodiment of
a telescopic strut than may be used for the landing gear of FIGS.
1A and 1B, illustrated in an stable fully extended and locked
state;
[0015] FIG. 2B is a sectional view of another particular embodiment
of a telescopic strut that may be used for the landing gear of
FIGS. 1A and 1B, illustrated in a stable fully extended and locked
state;
[0016] FIG. 3 is a top view of the rearmost part of a bogie of a
landing gear equipped with a pivotable axle according to a second
particular embodiment of the invention, illustrated in landing
position;
[0017] FIG. 4 is a top view of the rearmost part of a bogie of a
landing gear equipped with a pivotable axle according to a third
particular embodiment of the invention, illustrated in landing
position;
[0018] FIG. 5 is a top view of the rearmost part of a bogie of a
landing gear equipped with a pivotable axle according to a fourth
particular embodiment of the invention, illustrated in landing
position.
DETAILED DESCRIPTION OF THE FIGURES
[0019] In accordance to a first embodiment of the invention
illustrated at FIGS. 1A and 1B, there is provided a landing gear
with a six-wheel bogie 1. Said bogie 1 comprises an elongated beam
2 accommodating three axles, namely a front axle 3 and a center
axle 4 that are fixedly mounted on the elongated beam and a rear
axle 5 pivotally mounted at a rear end of the elongated beam 2
around a substantially vertical axis substantially crossing a
longitudinal axis of the rear axle 5. Each axle 3,4,5 carries a
pair of ground engaging wheels 6a, 6b. The bogie 1 is equipped with
travel limitations means 10 comprising a telescopic strut 11 having
ends 12,13 articulated to the elongated beam 2 and to the pivotable
axle 5 respectively.
[0020] In the situation illustrated at FIG. 1A, the pivotable axle
5 is in landing position and the telescopic strut 11 is in a fully
extended state, which is a lockable and therefore stable state, as
will be explained below in relation with FIG. 2. In the situation
illustrated at FIG. 1B, the pivotable axle 5 is in some angled
position, the telescopic strut 11 being in an intermediate position
between the fully extended state and a fully retracted state. It
will be immediately appreciated that the pivotable axle 5 can only
be pivoted one way. The illustrated bogie should therefore be
fitted on a left hand main landing gear of an aircraft, whereas the
corresponding right hand main landing gear should be fitted with a
symmetrical bogie having its rear axle pivoting the other way.
[0021] Referring now to FIG. 2A, and in accordance with a aspect of
the invention, the telescopic strut 11 includes a cylinder 14 for
sealingly receiving a sliding rod 15 equipped with a piston 16 that
defines into the cylinder 14 a shorten chamber 17 and a extend
chamber 18 that may be hydraulically serviced through a shorten
port 19 and an extend port 20 respectively if it is desired that
the telescopic strut 11 serve as an steering actuator.
[0022] The telescopic strut 11 is equipped with lock means 21 for
automatically locking the telescopic strut into the fully extended
state when the axle is brought back to the landing position. As
illustrated, the lock means 21 may be a claw lock mechanism,
including claw bendable fingers 22 attached to piston 16 and having
hook-like ends 23 for engaging a projection 24 of an inner
protruding portion 25 of cylinder 14. A locking piston 25 is
slidably mounted within the cylinder 14 to be operable between a
skipped position to which the locking piston 25 is pushed by the
fingers ends 23 when the telescopic strut arrives to the fully
extended state, and a covering or locking position (as shown) where
it is biased by springs 26 to cover the fingers ends 23 so as to
prevent the fingers 22 from bending when the finger ends 23 have
passed the projection 24. Unlock and lock ports 27,28 allow for
selectively moving the locking piston 25 between the skipped
position and the locking position.
[0023] The rear axle 5 pivoting may be operated in a passive
castoring mode. After landing with the axle being locked in the
landing position, and when the aircraft has slowed down below a
given speed, the locking piston 25 may be controlled as to uncover
the claw fingers 22, so that, in the event of the aircraft turning,
the rear axle of the inner main landing gear will naturally rotate
to track the turning of the aircraft, whereas the rear axle of the
outer main landing gear will stay in the landing position, although
unlocked. To relock the rears axles in the landing position prior
to take-off, the locking and unlocking ports of the locking piston
may be connected to the hydraulic return circuit, whereas the
extend chamber of the telescopic strut may be pressurized. If not
already in the fully extended state, the telescopic strut will then
be forced to extend until it reaches its fully extended state, in
which it will automatically lock, therefore causing the axle to be
locked into the landing position. This is a very simple, open-loop
style locking, with no need for accurate angular positioning of the
rear axle.
[0024] The rear axle 5 pivoting may also be operated in an active
steering mode. After landing with the axle being locked in the
landing position, and when the aircraft speed has slowed down below
a given speed, rotation of the rear axle 5 may be controlled so as
to be coordinated with steering of the nose landing gear. When the
nose steering angle has reached a given angle threshold (say 20
degrees), the locking piston 25 may be displaced to the skipped
position to uncover the claw fingers 22 in order to allow for
controlled steering of the rear axle 5 by means of the telescopic
strut 11 used as a steering actuator. The steering of the rear axle
5 may for instance be made proportional to the steering of the nose
landing gear wheels. The steering of the rear axle 5 may also be
performed in an active ON/OFF mode, in which, in response to the
nose steering angle reaching said given angle threshold, the bogie
rear axle is pivoted from its aligned position to a given maximum
angled position, defined by the telescopic strut 11 reaching its
fully compressed configuration. Having the rear axle pivoting back
to the landing position may be commanded in response to the nose
steering angle crossing back the same angle threshold, or another
angle threshold.
[0025] It will be appreciated that the telescopic strut 11 is
equipped with four ports (two for displacing the piston rod, and
two for independently controlling the locking piston). The
telescopic strut 11 may preferably be operated as follows. When it
is desired to unlock the telescopic strut 11, the extend port 20
may be pressurized first so as to offload the locking mechanism.
Then the unlock port 27 may be pressurized, so as to move the
piston 25 to its skipped position. This not only alleviates the
risk of a jammed locking piston, but also allows for a soft
unlocking, avoiding any unlocking shock sound that is often
generated when unlocking under load. Then, the extend port 20 may
be connected to return, whereas the shorten port 19 may be
pressurized in order to steer the rear axle 5. The unlock and lock
ports 27,28 may then be connected to return.
[0026] It will then be appreciated that the telescopic strut 11 is
then used as a steering actuator, but still serving as axle travel
limitation means. To lock the rear axle 5 in the landing position,
it suffices to pressurize the extend chamber 18 until the
telescopic strut 11 is brought back to the fully extended position
in which it automatically locks. There is no need for an accurate
and difficult controlled positioning of the axle to allow it to be
locked.
[0027] Obviously, the telescopic may be positioned the other side
of the bogie beam, still allowing the axle to pivot the same way as
indicated by the arrow of FIG. 1. The stable lockable state of the
telescopic strut will then correspond to a fully compressed state.
A telescopic strut 11' suitable for being locked in the fully
compressed state is illustrated at FIG. 2B. The telescopic strut
11' includes a cylinder 14' for sealingly receiving a sliding rod
15' equipped with a piston 16' that defines into the cylinder 14' a
shorten chamber 17' and a extend chamber 18' that may be
hydraulically serviced through a shorten port 19' and an extend
port 20' respectively if it is desired that the telescopic strut
11' serve as a steering actuator.
[0028] The telescopic strut 11' is equipped with lock means 21' for
automatically locking the telescopic strut 11' into the fully
compressed state when the rear axle 5 is brought back to the
landing position. As illustrated, the lock means 21' may be a
segment lock mechanism, including a plurality of radially movable
segments 22' received in a recess portion of piston 16'. A locking
piston 25' is slidably mounted within the cylinder 14' to be
operable between a skipped position to which the locking piston 25'
is pushed by the segments 22' when the telescopic strut arrives to
the fully compressed state, and a locking position (as shown) where
it is biased by spring 26' to radially urge the segments 22'
against a recessed portion 24' of cylinder 14', so as to form an
obstacle preventing the piston 16' from axially moving. Locking and
unlocking ports 27',28' allow for selectively moving the locking
piston 25' between the skipped position and the locking
position.
[0029] As previously, the shorten port 19' of the telescopic strut
11' may preferably be pressurized before pressurizing the unlock
port 27', so as to offload the segments 22' and ease the unlocking
operation. Only after the locking piston 25' has moved to the
skipped position, the extend port 20' may be pressurized to cause
the telescopic strut to extend and steer the rear axle 5.
[0030] This four-ports arrangement allows for a reverse actutation
before unlocking so as to offload the lock mechanism and ease the
unlocking operation. Any type of locking may be used, like segment,
claw or ball lock, to lock the telescopic strut in the fully
compressed or fully extended state. This kind of actuatable
telescopic strut may of course find other applications, for
instance to effect extension and retraction of a landing gear with
respect to an aircraft structure.
[0031] However, when the risks of jamming the internal mechanism or
generating a shock sound is expected to be small, one may
contemplate using a more classical two-port internally lockable
telescopic strut, in which the locking piston is pressurized in
conjunction with the extend and shorten ports. One may even use a
simple telescopic strut with no internal lock, in conjunction with
some external locking means.
[0032] As a variant, bringing the rear axle back to the landing
position may be helped or even solely effected by applying some
differential braking on the wheels of the rear axle so as to make
the rear axle pivoting back to the landing position while the
aircraft is moving.
[0033] In accordance with a second embodiment of the invention
illustrated at FIG. 3, on which like elements have references
augmented of a hundred, the travel limitation means 110 include two
members 130, 131 articulated to one another to form a knee 132
thereof, member 130 being articulated to the elongated beam 102,
whereas member 131 is articulated to the pivotable rear axle 105.
In the position illustrated on FIG. 3, the members 130,131 are in a
substantially aligned configuration, which is a stable state
thereof corresponding to the landing position of the axle 105.
[0034] The substantially aligned configuration is geometrically
defined by providing the members 130, 131 with corresponding mutual
abutment means 133,134. It is known to design the abutment means so
as to let the members abut in a slightly overcentered position (in
which the knee 132 has slightly crossed an imaginary line passing
through the end articulations of the members before the members
abut against one another). A telescopic actuator 135 is pivotally
mounted on the elongated beam 102 by means of a pivot 136 to engage
the knee 132. The actuator 135 extends substantially perpendicular
to the elongated beam 102 and finds itself in an almost fully
compressed state when the members 130,131 are in the substantially
aligned configuration. The members 130,131 may be locked in the
substantially aligned configuration by keeping the shorten chamber
thereof pressurized. Alternatively, spring means may be arranged
between the two members, or between one member and the elongated
beam, or else between one member and the rear a axle, so as to
confirm the members 103,131 in mutual abutment. Allowing the rear
axle 105 to pivot is effected by pressurising the extend chamber of
the actuator 135, therefore causing the members 130,131 to move out
of alignment, which causes the rear axle 105 to pivot according to
the arrow on the figure.
[0035] Bringing back and locking the rear axle 105 in the landing
position can easily be achieved by pressurizing the shorten chamber
of the actuator 135, until the travel limitation means 110 are
brought back to their stable aligned configuration in which they
are automatically locked.
[0036] In accordance with a third embodiment of the invention
illustrated at FIG. 4, on which like elements have references
augmented of a hundred, the travel limitation means 210 still
include a two articulated members 230,231 arrangement with abutment
means 233,234 that defines a substantially aligned configuration
thereof, which constitutes a stable state thereof corresponding to
a landing position of the rear axle 205. The member 231 which is
articulated to the elongated beam 202 incorporates a lever 235 that
is engaged by a telescopic actuator 233 that extends along the
elongated beam 202. By contrast to the previous embodiment, the
illustrated aligned configuration of the members 230,231 now
corresponds to an almost fully extended state of the actuator
233.
[0037] The actuator 233 may serve to lock the members 230,231 in
the substantially aligned configuration by keeping the extend
chamber thereof pressurized. Alternatively, spring means may be
arranged so as to confirm the abutment means in mutual abutment.
Pivoting of the rear axle 205 is effected by pressurising the
shorten chamber of the actuator 235, therefore causing the members
230,231 to move out of alignment, which causes the rear axle 205 to
pivot according to the arrow on the figure.
[0038] Bringing back and locking the rear axle in the landing
position can be easily achieved by pressurizing the extend chamber
of the actuator 235, until the travel limitation means 210 are
brought back to their stable aligned configuration in which they
are automatically locked.
[0039] In accordance to a fourth embodiment illustrated on FIG. 5,
in which like elements have a reference augmented of a hundred, the
travel limitation means 310 are still comprised of two articulated
members 330,331 respectively articulated to the elongated beam 302
and to one side of the rear axle 305 and having mutual abutment
means 333,334. A telescopic actuator 335 extends between a knee 332
of the members 330,331, and an attachment 336 protruding from the
other side of the axle 305. Operation of the rear axle 305 is
substantially similar to that of the second and third embodiments.
However, having the actuator linked to the rear axle 305 allows for
some mechanical advantage when the members are out of
alignment.
[0040] The invention is not limited to what has been described, but
includes any variant falling within the ambit of the claims.
[0041] In particular, while only the rear axle has been pictured to
pivot, the invention may be applied also to another axle of the
bogie. This invention is of course not limited to six wheels
bogies, but applies to any bogie having at least one pivotable
axle. Although the rear axle is pivoted around a substantially
vertical axis substantially crossing a longitudinal axis of the
rear axle, there may be some slight offset so as to generate a
biasing torque to help the axle pivoting back to its landing
position. The pivot axis may also be slightly canted.
[0042] While the actuators shown are of the linear, telescopic
type, other actuators may be used, such as rotative actuators,
especially in the second, third and fourth embodiment, where the
member articulated on the elongated beam may be engaged by a
rotative hydraulic or electric motor at its articulation on the
elongated beam.
[0043] While the two articulated members type travels limitation
means are pictured in a stable state corresponding to the members
being substantially aligned with one member prolonging the other
member, the stable state thereof can also correspond to an aligned
folded back state in which one member extends under the other.
* * * * *