GB2585823A - A landing gear drive system clutch assembly - Google Patents

A landing gear drive system clutch assembly Download PDF

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Publication number
GB2585823A
GB2585823A GB1909114.9A GB201909114A GB2585823A GB 2585823 A GB2585823 A GB 2585823A GB 201909114 A GB201909114 A GB 201909114A GB 2585823 A GB2585823 A GB 2585823A
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United Kingdom
Prior art keywords
assembly
gear
drive
driving torque
driven transmission
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Granted
Application number
GB1909114.9A
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GB2585823B (en
GB201909114D0 (en
Inventor
Ian Thompson Robert
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Airbus Operations Ltd
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Airbus Operations Ltd
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Priority to GB1909114.9A priority Critical patent/GB2585823B/en
Publication of GB201909114D0 publication Critical patent/GB201909114D0/en
Publication of GB2585823A publication Critical patent/GB2585823A/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C25/405—Powered wheels, e.g. for taxing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C25/34—Alighting gear characterised by elements which contact the ground or similar surface  wheeled type, e.g. multi-wheeled bogies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C25/00—Alighting gear
    • B64C25/32—Alighting gear characterised by elements which contact the ground or similar surface 
    • B64C25/34—Alighting gear characterised by elements which contact the ground or similar surface  wheeled type, e.g. multi-wheeled bogies
    • B64C25/36—Arrangements or adaptations of wheels, tyres or axles in general
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/80—Energy efficient operational measures, e.g. ground operations or mission management

Abstract

A landing gear drive system clutch assembly and method of operation 300 comprising a drive gear 320, a driven transmission 350 with an intermediate gear 340 for receiving driving torque from the drive gear and transmitting driving torque to the driven transmission. The drive gear being engageable with the intermediate gear which is engageable with the driven transmission. There is also disclosed an aircraft landing gear comprising a strut with a lever arm (130, Fig 1b) and a drive system with a drive shaft (240, fig 1b) located within an axel and a drive shaft (230, fig 1b) located in the lever arm. There is further disclosed a drive system and method of operation comprising a drive shaft located in a landing gear axel, a clutch assembly comprising a drive gear and a driven transmission, wherein the drive gear is engageable with the driven transmission. There is further disclosed a landing gear drive clutch assembly and method of operation comprising a drive gear assembly and a driven transmission, the drive gear comprising two pinion gears 323, 324 mounted either side of a rotational axis of the driven transmission which can individually engage the driven transmission via movement of a lever.

Description

A LANDING GEAR DRIVE SYSTEM CLUTCH ASSEMBLY
BACKGROUND OF TILE INVENTION
[0001] The present disclosure relates to a landing gear drive system clutch assembly.
[0002] The present invention concerns landing gear drive systems and aircraft landing gear. More particularly, but not exclusively, this invention concerns a landing gear drive system clutch assembly comprising a drive gear assembly for receiving driving torque from a landing gear drive motor, and a driven transmission assembly for transmitting driving torque to a wheel of a landing gear. The invention also concerns a landing gear drive system, an aircraft landing gear, a landing gear drive system and methods of operating a landing gear and a landing gear drive system.
[0003] Various e-taxi systems have been described and proposed (for example, in W02014/023941) where a landing gear drive system (comprising a motor, a drive gear connected to the motor, and a driven gear that can be driven by the drive gear and being connected to a wheel) is used to drive one or more wheels of a landing gear of an aircraft in a forwards or backwards direction. However, often these e-taxi systems have been designed to be retrofitted onto existing pre-designed landing gear arrangements. Hence, these systems are not optimised. In addition, it is often difficult to allow for the amount of deflection between the drive gear and driven gear, for example, particularly on touch down of the aircraft.
[0004] The present invention seeks to mitigate the above-mentioned problems.
Alternatively or additionally, the present invention seeks to provide an improved landing gear drive system clutch assembly.
SUMMARY OF THE INVENTION
[0005] The present invention provides, according to a first aspect, a landing gear drive system clutch assembly comprising i) a drive gear assembly for receiving driving -2 -torque from a landing gear drive motor, ii) a driven transmission assembly for transmitting driving torque to a wheel of a landing gear, and iii) an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly.
[0906] By providing the drive gear assembly with a disengaged position and by also providing the intermediate gear assembly with a disengaged position, there are two disengagement points in the drive path of the clutch assembly between the drive gear assembly and the driven transmission assembly. This reduces the risk of inadvertent engagement of the driven transmission assembly by the drive gear assembly, and prevent damage.
[0007] During engagement movement, the drive gear assembly moves towards the intermediate gear assembly (and driven transmission assembly), and the intermediate gear assembly moves towards the driven transmission assembly.
[0008] Preferably, movement of the drive gear assembly towards its engaged position (i.e. the engagement position of the drive gear assembly) causes the intermediate gear assembly to move towards its engaged position (i.e. the engagement position of the intermediate gear assembly). This means that the two engagement movements can he caused by a single movement of the drive gear assembly.
[0909] More preferably, movement of the drive gear assembly towards its engaged position pushes the intermediate gear assembly to move towards its engaged position. -3 -
[0010] Even more preferably, during movement of the drive gear assembly towards its engaged position, a non-torque transmitting part of the drive gear assembly pushes against a non-torque transmitting part of the intermediate gear assembly. This means that the pushing is not having to be performed by a torque transmitting part (that is likely to be drive to rotate). Hence, wear is reduced.
[0011] Even more preferably, the non-torque transmitting part of the drive gear assembly and the intermediate gear assembly form a roller and abutment surface pair.
[0012] Even more preferably, the non-torque transmitting part of the drive gear assembly is a roller and the non-torque transmitting part of the intermediate gear assembly is an abutment surface.
[0013] Preferably, movement of the drive gear assembly towards its disengaged position (i.e. the disengagement position of the drive gear assembly) causes the intermediate gear assembly to move towards its disengaged position (i.e. the disengagement position of the intermediate gear assembly).
[0014] More preferably, the intermediate gear assembly is biased towards its disengaged position by a biasing element. For example, the biasing element may be a spring. The biasing element may urge the intermediate gear assembly away from the driven transmission assembly. The biasing element may urge the intermediate gear assembly towards the drive gear assembly.
[0015] Preferably, the intermediate gear assembly comprises a clutch surface for engaging with a corresponding clutch surface on the driven transmission assembly. The intermediate gear assembly clutch surface may fit inside driven transmission assembly clutch surface. In other words, the driven transmission assembly clutch surface may be located outside the intermediate gear assembly clutch surface. For example, the driven transmission assembly clutch surface may be further away from a drive shaft of the clutch assembly (e.g. a drive shaft of the intermediate gear assembly and/or a drive shaft of the driven transmission assembly) than the intermediate gear assembly clutch surface.
[0016] More preferably, the intermediate gear assembly clutch surface is a conic surface and the driven transmission assembly clutch surface is a corresponding conic surface. The narrower ends of the conic surfaces may he nearer the driven transmission -4 -assembly, and the wider ends of the conic surfaces may be nearer the drive gear assembly.
[0017] Preferably, the drive gear assembly comprises an input gear for receiving driving torque from a landing gear drive motor, and two pinion gears both in driving torque connection with the input gear, and both arranged to he connected to the intermediate gear assembly so as to transmit driving torque to the intermediate gear assembly.
[0018] More preferably, the two pinion gears are mounted on either side of a rotation axis of the intermediate gear assembly, on a pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the intermediate gear assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the intermediate gear assembly. The rotation axis of the intermediate gear assembly may he the rotation axis of an input gear of the intermediate gear assembly. The movement towards the intermediate gear assembly may be movement towards an input gear of the intermediate gear assembly. This allows pivoting of the lever to determine which pinion gear engages the (input gear of) the intermediate gear assembly. Hence, this determines which direction the intermediate gear assembly is driven. This allows the clutch assembly to drive an aircraft wheel forward or backwards, using the same wheel and the same drive shaft. This means the clutch assembly and/or landing gear drive system is lighter. Pivoting of the lever may be caused by an actuator able to move in two directions (e.g. extend to pivot the lever in one direction and retract to pivot the lever in the opposite direction).
[0019] Even more preferably, the pivotable lever is moveable between (i) a first pinion gear engaged position, in which the first pinion gear is in driving torque connection with the intermediate gear assembly, and (ii) a second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the intermediate gear assembly, through (iii) a neutral position, in which neither of the pinion gears are in driving torque connection with the intermediate gear assembly.
[0020] According to a second aspect of the invention there is also provided a landing gear drive system comprising the landing gear drive system clutch assembly as described -5 -above, and further comprising a wheel drive shaft and wherein the driven transmission assembly is ranged to be connected to the wheel drive shaft so as to transmit driving torque to the wheel of a landing gear.
[0021] Preferably, the wheel drive shaft is configured for location within a landing gear wheel axle.
[0022] Preferably, the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the intermediate gear assembly and wherein movement of the drive gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft. Here, the movement of engagement is lateral to the drive direction of an aircraft. The movement of disengagement may also he lateral. Hence, the engagement/disengagement are largely unaffected by fore/aft shock loads that may occur during landing of the aircraft. The output element may be a gear. The input element may be a gear. The input and output gear elements may be arranged to rotate about axes that are transverse to each other.
[0023] Preferably, the intermediate gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly and wherein movement of the intermediate gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft. Here, the movement of engagement is lateral to the drive direction of an aircraft. The movement of disengagement may also be lateral. Hence, the engagement/disengagement are largely unaffected by fore/aft shock loads that may occur during landing of the aircraft.
[0024] According to a third aspect of the invention there is also provided an aircraft landing gear comprising i) a main strut having a first end region and a second opposite end region, the main strut being for connection at its first end region to an aircraft, ii) a lever arm having a first end region and a second opposite end region, the lever arm being pivotally connected at its first end region to the second end region of the main strut, iii) a wheel axle mounting one or more wheels, the wheel axle being connected transversely to the lever arm in the second end region of the lever arm, and iv) a drive system, the drive -6 -system comprising a wheel drive shaft for driving rotation of the one or more wheels, the wheel drive shaft being located within the wheel axle, a main drive shaft for driving rotation of the wheel drive shaft, the main drive shaft being located within the lever arm, and a motor and/or gearing assembly for driving rotation of the main drive shaft, the motor or gearing assembly being located adjacent to the first end region of the lever arm.
[0025] Here, the motor and/or gearing assembly, which are often some of the heaviest parts of a drive system, are mounted near to the first end of the lever arm. In other words, one or both of them are located near to where the lever arm is pivotally connected to the main strut. Hence, when the lever arm pivots in relation to the main strut, for example during shock absorbing such as when the wheel(s) contact the ground, the motor and/or gearing assembly only move a relatively small distance in relation to the main strut. This means that the change of inertia of the motor and/or gearing assembly is relatively low and so the change of inertia of the unsprung mass is low and so the touchdown characteristics, such as dynamic landing loads, of the landing gear, and the aircraft as a whole, are largely unaffected.
[0026] The landing gear may be extendable/retractable in relation to an aircraft. For example, the main strut may be suitable for being pivotally connected to an aircraft at its first end region.
[0027] As a first alternative for the motor being located adjacent to the first end region of the lever arm, the motor is located within the first end region of the lever arm.
[0028] As a second alternative for the motor being located adjacent to the first end region of the lever arm, the motor is located externally at the first end region of the lever arm.
[0029] As a first alternative for the gearing assembly being located adjacent to the first end region of the lever arm, the gearing assembly is located within the first end region of the lever arm.
[0930] As a second alternative for the gearing assembly being located adjacent to the first end region of the lever arm, the gearing assembly is located externally at the first end region of the lever arm. -7 -
[0031] Preferably, the motor and gearing assembly are located adjacent to each other, for example in the same location with respect to the lever arm (i.e. either both located externally or both located within the lever arm).
[0032] Preferably, the lever arm is a trailing link extending in an aft direction from the main strut, in relation to an aircraft flight direction.
[0033] Preferably, the wheel axle intersects with the lever arm to provide an intersection region of the wheel axle and second end region of the lever arm.
[0034] More preferably, the drive system further comprises a clutch assembly for controlling a driving connection of the main drive shaft and the wheel drive shaft, the clutch assembly being located in the intersection region of the second end region of the lever arm and the wheel axle.
[0035] Preferably, the aircraft landing gear comprises a clutch assembly as described above or below. The clutch assembly may be located in the intersection region.
[0036] According to a fourth aspect of the invention there is also provided a landing gear drive system comprising i) a wheel drive shaft configured to be located within a landing gear wheel axle, and ii) a clutch assembly, the clutch assembly comprising a drive gear assembly for receiving driving torque from a landing gear drive motor, and a driven transmission assembly, capable of driving torque connection to the wheel drive shaft to provide driving torque to a wheel of a landing gear, wherein the drive gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the driven transmission assembly, and wherein the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly and wherein movement of the drive gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft.
[0037] Here, as the engagement movement (i.e. the movement of the drive gear assembly towards its engagement position) is along the direction of the wheel drive shaft, it is largely unaffected by fore/aft shock loads that occur during landing, for example. -8 -
This reduces the risk of inadvertent engagement of the driven transmission assembly by the drive gear assembly, and prevent damage.
[0038] Preferably, the clutch assembly further comprises an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly. By providing the drive gear assembly with a disengaged position and by also providing the intermediate gear assembly with a disengaged position, there are two disengagement points in the drive path of the clutch assembly between the drive gear assembly and the driven transmission assembly. This reduces the risk of inadvertent engagement of the driven transmission assembly by the drive gear assembly, and prevent damage.
[0039] More preferably, the intermediate gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly and wherein movement of the intermediate gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft. Here, as the engagement movement (i.e. the movement of the intermediate gear assembly towards its engagement position) is along the direction of the wheel drive shaft, it is largely unaffected by fore/aft shock loads that occur during landing, for example. This reduces the risk of inadvertent engagement of the driven transmission assembly by the drive gear assembly, and prevent damage.
[0040] Preferably, the clutch assembly is as described above or below. -9 -
1-00411 According to a fifth aspect of the invention there is also provided a landing gear drive system clutch assembly comprising i) a drive gear assembly for receiving driving torque from a landing gear drive motor, ii) a driven transmission assembly for transmitting driving torque to a wheel of a landing gear, and wherein the drive gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the driven transmission assembly, and wherein the drive gear assembly comprises an input gear for receiving driving torque from a landing gear drive motor, and two pinion gears for transmitting driving torque to the driven transmission assembly, wherein the input gear is capable of driving torque connection with the pinion gears, and wherein the two pinion gears are mounted on either side of a rotation axis of the driven transmission assembly, on a pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the driven transmission assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the driven transmission assembly.
[0042] By having two pinion gears that are able to be driven by the same input gear and having the pinion gears on opposite sides in relation to the rotation axis of the driven transmission assembly allows one of the pinion gears to be able to drive the drive gear assembly in a first direction and the other pinion gear to be able to drive the drive gear assembly in the opposite direction. This enables the drive system clutch assembly to drive the driven transmission assembly in a forwards and a backwards direction, depending on which direction the pivotable lever is moved. Hence, a compact clutch assembly can be provided that provides for forwards and backwards movement. In this aspect, an intermediate gear assembly may not be required.
[0043] Preferably, the pivotable lever is moveable between a first pinion gear engaged position, in which the first pinion gear is in driving torque connection with the driven transmission assembly, and second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the driven transmission assembly, -10 -through a neutral position, in which neither of the pinion gears are in driving torque connection with the driven transmission assembly.
[0044] Preferably, the clutch assembly further comprises an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between the disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and the engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly. By providing the drive gear assembly with a disengaged position and by also providing the intermediate gear assembly with a disengaged position, there are two disengagement points in the drive path of the clutch assembly between the drive gear assembly and the driven transmission assembly. This reduces the risk of inadvertent engagement of the driven transmission assembly by the drive gear assembly, and prevent damage.
[0045] More preferably, the two pinion gears are mounted on either side of a rotation axis of the intermediate gear assembly, on the pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the intermediate gear assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the intermediate gear assembly.
[0046] Even more preferably, the pivotable lever is moveable between the first pinion gear engaged position, in which the first pinion gear is in driving torque connection with the intermediate gear assembly, and the second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the intermediate gear assembly, through the neutral position, in which neither of the pinion gears are in driving torque connection with the intermediate gear assembly.
[0047] According to a sixth aspect of the invention there is also provided a method of operating a landing gear drive system, the method comprising the steps of i) providing driving torque from a landing gear drive motor to a drive gear assembly, ii) moving the drive gear assembly in relation to an intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, iii) moving the intermediate gear assembly in relation to a driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly, and iv) providing driving torque from the driven transmission assembly to a wheel of a landing gear.
[0048] According to a seventh aspect of the invention there is also provided a method of operating a landing gear, the method comprising the steps of i) providing driving torque from a landing gear drive motor to a drive gear assembly, ii) moving the drive gear assembly in relation to a driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the driven transmission assembly, and iii) providing driving torque from the driven transmission assembly to a wheel drive shaft located within a landing gear wheel axle of the landing gear, and wherein the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly, and wherein the movement of the drive gear assembly between the disengaged and engaged positions comprises movement of the output element along the direction of the axis of the wheel drive shaft. In this aspect, an intermediate gear assembly may not be required.
[0049] According to an eighth aspect of the invention there is also provided a method of operating a landing gear drive system, the method comprising the steps of, in a forward driving mode i) providing driving torque from a landing gear drive motor to a drive gear -12 -assembly, the drive gear assembly comprising an input gear for receiving driving torque from the landing gear drive motor, ii) moving the drive gear assembly in relation to a driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and a forwards engaged position in which a first of two pinion gears of the drive gear assembly is in driving torque connection with the driven transmission assembly, iii) providing driving torque from the driven transmission assembly to a wheel of a landing gear, and, in a reverse driving mode i) providing driving torque from the landing gear drive motor to the input gear of the drive gear assembly, ii) moving the drive gear assembly in relation to the driven transmission assembly between the disengaged position and a reverse engaged position in which a second of two pinion gears of the drive gear assembly is in driving torque connection with the driven transmission assembly, iii) providing driving torque from the driven transmission assembly to a wheel of a landing gear, wherein the two pinion gears are mounted on either side of a rotation axis of the driven transmission assembly, on a pivotable lever, wherein the step of moving the drive gear assembly between the disengaged position and the forwards engaged position comprises movement of the pivotable lever in a first direction causing the first pinion gear to move towards the driven transmission assembly and wherein the step of moving the drive gear assembly between the disengaged position and the reverse engaged position comprises movement of the pivotable lever in a second direction causing the second pinion gear to move towards the driven transmission assembly. In this aspect, an intermediate gear assembly may not be required.
[0050] It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.
-13 -
DESCRIPTION OF THE DRAWINGS
[0951] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: [0052] Figure la shows an exploded perspective view of a landing gear according to a first embodiment of the invention; [0053] Figure lb shows an enlarged perspective view of the trailing lever arm and wheel axle of the landing gear of Figure 1; [0054] Figure 2a shows an internal view of the clutch assembly shown in Figure lb, the clutch assembly in a neutral position; [0055] Figure 2b shows the clutch assembly of Figure 2a, the clutch assembly in an intermediate position, prior to forwards driving; [0056] Figure 2c shows the clutch assembly of Figure 2a, the clutch assembly in a forwards driving position; [0057] Figure 2d shows the clutch assembly of Figure 2a, the clutch assembly in a reverse driving position; [0058] Figure 3 shows an enlarged view of a first alternative trailing lever arm and wheel axle arrangement; [0059] Figure 4 shows an enlarged view of a second alternative trailing lever arm and wheel axle arrangement; [0960] Figure 5 shows an enlarged view of a third alternative trailing lever arm and wheel axle arrangement; [0961] Figure 6 shows an enlarged view of a fourth alternative trailing lever arm and wheel axle arrangement; and [0062] Figure 7 shows a front view of an aircraft including two main landing gears according to Figure la.
DETAILED DESCRIPTION
[0063] Figure la shows an exploded perspective view of a landing gear 100 according to a first embodiment of the invention. The landing gear 100 includes a main -14 -strut 110 (comprising a main fitting and a lower slider portion). At a top end of the main strut are two connections 111, 112 to enable the landing gear to be pivotally connected to an aircraft. About two thirds of the way down the main strut 110 is a bracket 113 for pivotally mounting a lower end of a side arm 120.
[0064] The side arm 120 comprises two parts 121, 122, with a hinge 123 in between the two parts approximately half way along the side arm 120. It is the lower part 122 that is mounted to the bracket 113 at mount point 125. The upper part 121 is pivotally mounted to the aircraft at mounting point 124.
[0065] The hinge 123 also mounts a lock stay 126 (also formed of two parts pivoted to each other half way along the length of the lock stay) and this lock stay is pivotally connected at its other end to the main strut 1 10.
[0066] This arrangement of main strut 110, side arm 120 and lock stay 126 allows the landing gear 100 to he extended and retracted in relation to the aircraft.
[0067] At a lower end of the main strut 110, there is a sleeve 115 that provides a pivotal connection point 116 at a fore side (in relation to the aircraft flight direction) of the main strut 110. The main strut 110 also comprises a pivotal connection point 114 at the bottom of the main strut 110, in line with the axis of the main strut.
[0068] A lever arm 130 is pivotally connected to the lower end of the main strut 110.
The lever arm 130 comprises a bracket 131 along a top edge of the leer arm, the bracket 131 providing a first pivotal connection 132 at an upper end 136 (shown in Figure lb) of the lever arm and a second pivotal connection 133 about halfway along the length of the lever arm. The first pivotal connection 132 is attached to pivotal connection 116 on the sleeve 115. Pivotal connection 116 is where braking loads are reacted. A strut 134 is connected to the pivotal connection 133 at its lower end and connected to pivotal connection 114 of the main strut 110 at its upper end.
[0069] At a lower end 135 of the lever arm 130 is a wheel axle 140 extending transversely to both sides of the lever arm; to the left (as viewed in Figure I a) 142 and right (as viewed in Figure I a) 142, as shown in Figure I a. The wheel axle mounts a wheel 150 at each end; a left wheel 151, as shown, and a right wheel (152, but not shown here for clarity).
-15 - [0070] When the landing gear is mounted on an aircraft, as shown mounted as two main landing gears 100a, 100b on aircraft 1000 in Figure 7, the lever arm 130 extends aft from the main strut 100, i.e. away from the forwards direction of travel of the aircraft 1000. When the aircraft lands or when the aircraft is moving on a runway, the main strut 110 extends and retracts to allow for absorption of shock loads. When this happens, the lever arm 130 pivots at point 132, 116.
[0071] Figure lb shows an enlarged perspective view of the trailing lever arm 130 and wheel axle 140 of the landing gear 100 of Figure 1. Here, it can he seen that there is a drive assembly 200 provided. The drive assembly 200 comprises a motor 210 located at the top of and just external to the lever arm 130 and a gearbox assembly 220 located within the lever arm 130, at the very top, adjacent to the motor 210. A main drive shaft 230 extends through the lever arm 130 from the gearbox assembly 220 to the intersection of the lever arm 130 and wheel axle 140 where it connects to a clutch assembly 300. There is a wheel drive shaft assembly 240 extending transversely from the clutch assembly 300 along the right side 142 of the wheel axle 140 to a wheel drive interface 250 at a centre of the wheel for interfacing and driving the right wheel 152 (not shown).
[0072] Figure 2a shows an internal view of the clutch assembly 300 shown in Figure lb, the clutch assembly in a neutral position. The clutch assembly 300 can be considered to be made up of several different mechanisms, which will be described later. These are a drive gear mechanism 320, an actuator mechanism 330, an intermediate gear mechanism 340 and a driven transmission mechanism 350.
[0073] The clutch assembly 300, and the different mechanisms of it, is contained within a cylindrical housing 310, which is located within and at the intersection of the lever arm 130 and wheel axle 141, 142. Figure 2a is an internal view of the clutch assembly 300, as seen cutaway from the bottom of the lever arm 130 looking into the lever arm. The casing includes an internal opening 311 for housing a first end 342 of a drive rod 341 that is part of the intermediate gear mechanism 340 (that will he described later). At the opposite side of the casing 310 is a wider neck portion 313 for supporting the driven transmission mechanism 350 (which will also he described later). The casing 310 also comprises an internal pivotal connection point 312 for pivotally mounting the -16 -actuator mechanism 330 within the casing (again, this will be described later). This connection point 312 is above the internal opening 311, as shown in Figure 2a.
[0074] The drive gear mechanism 320 of the clutch assembly 300 will now be described. This mechanism comprises an input gear 322 that is connected to the main drive shaft 230 so that when the main drive shaft 230 is rotated by the motor 210 and gearbox assembly 220, the input gear 322 also rotates. This input gear 322 is located at the centre of the casing 310. The input gear 322 is mounted adjacent a central portion of a pivotable lever 321. The input gear 322 and lever 321 are mounted on and are rotatable about the same mounting shaft.
[0075] On a first end (the end shown uppermost in Figure 2a) of the lever 321 is rotationally mounted a first output gear 323. This first output gear 323 has teeth, which correspond and mesh with teeth of the input gear 322 so that when the input gear 322 rotates, the first output gear 323 rotates in the opposite direction. Similarly, on a second end (the end shown lowermost in Figure 2a) of the lever 321 is rotationally mounted a second output gear 324. This second output gear 324 also has teeth which correspond and mesh with teeth of the input gear 322 so that when the input gear 322 rotates, the second output gear 324 rotates in the opposite direction (the same direction as the first output gear 323). Each output gear 323, 324 is rigidly connected to a pinion gear (first 325 and second 326 pinion gears respectively), so that when the first and second output gears 323, 324 rotate, so do the pinion gears 325, 326 (in the same direction as the output gears 323, 324).
[0076] The pivotable lever 321 also comprises two abutment rollers 327, 328. The first abutment roller 327 is located in between the input gear 322 and the first pinion gear 325. Similarly, the second abutment roller 328 is located in between the input gear 322 and the second pinion gear 326. The purpose of these abutment rollers 327, 328 will be described later.
[0077] Finally, the lever 321 also comprises a lug providing a pivotal connection 329 to the actuator mechanism 330. This pivotal connection is below the internal opening 311 of the casing, as shown in Figure 2a.
-17 - [0078] The actuator mechanism 330 of the clutch assembly 300 will now be described. This mechanism comprises a screw actuator 331 with a screw portion 332 extendable and retractable (driven electrically) with respect to a screw casing 333 so that the length of the actuator 331 can vary. At a first end 334 of the actuator (the casing end), the actuator 331 is pivotally mounted to the internal pivotal connection point 312 of the casing 310. At a second end 335 of the actuator (the screw end), the actuator 331 is pivotally mounted to the pivotal connection 329 on the lug of the lever 321.
[0079] Hence, when the actuator 331 is retracted, the actuator pulls on the pivotal connection 329, the lug and the lever 321, such that the lever 321 rotates in a clockwise direction, from the neutral position of Figure 2a to the positions shown in Figures 2b and 2c, as will be described later. Similarly, when the actuator 331 is extended, the actuator pushes the pivotal connection 329, the lug and the lever 321, such that the lever 321 rotates in an anti-clockwise direction, from the neutral position of Figure 2a to the position shown in Figures 2d, as will be described later.
[0080] The actuator mechanism 330 includes a "power off' brake (not shown) to prevent uncommanded movement.
[0081] The intermediate gear mechanism 340 of the clutch assembly 300 will now be described. This mechanism comprises the drive rod 341 previously mentioned, which is mounted within the opening 311 of the casing 310. The cylindrical drive rod 341 is slidably mounted in the opening 311 such that its first end 342 can move along within the opening. The drive rod 341 extends past the centre of the casing 310 and past the drive gear mechanism 320. At the second end of the drive rod 341 is disc portion 343 with a much larger diameter than the drive rod 341. The disc portion 343 has an abutment surface 344 which faces towards the first end 342 of the drive rod and hence, faces the drive gear mechanism 320.
[0082] When the actuator 331 is retracted, the actuator pulls the pivotal connection 329, the lug and the lever 321, and causes the lever 321 to rotate in a clockwise direction, as described above. This causes the abutment roller 327 to abut against the abutment surface 344 and push against it. This causes the drive rod 341 to slide in the opening 311 (right, as shown in Figure 2a). Similarly, when the actuator 331 is extended, the actuator -18 -pushes the pivotal connection 329, the lug and the lever 321, and causes the lever 321 to rotate in an anti-clockwise direction, as described above. This causes the abutment roller 328 to abut against the abutment surface 344 and push against it. This also causes the drive rod 341 to slide in the opening 311 (right, as shown in Figure 2a).
[0083] The disc portion 343 also mounts a cog wheel 345 such that it can rotate about the axis of the drive rod 341. The cog wheel 345 has teeth that are angled outwards (i.e. outwards from the rotational axis, bevelled) and also angled radially (i.e. around the circumference) along its depth. This can he seen in Figure 2a where the cog wheel 345 has each tooth extending outwards and also around the circumference as the tooth extends from the front of the cog wheel (adjacent the abutment surface 344) to the hack of the cog wheel 345. The teeth of the pinion gears 325, 326 are correspondingly shaped so that when they mesh with the cog wheel 345 (as will he described later), the pinion gear 325 or 326 drives rotation of the cog wheel 345, even though the pinion gears 325, 326 rotate about an axis that is perpendicular to the rotation axis of the cog wheel 345.
[0084] Behind the cog wheel 345, the disc portion mounts an inner cone clutch drive surface 346. The inner cone clutch drive surface 346 comprises an inwardly (i.e. towards the rotational axis as it extends away from the cog wheel 345) sloped surface extending around the rotational axis of the disc portion 343, drive rod 341 and cog wheel 345.
[0085] There is a spring channel provided by shaft walls 347 inside the inner cone clutch drive surface 346, and there is a compression spring 348 contained within the channel. The compression spring 348 is located such that a central compression axis of the spring 348 is in line with the rotational axis of the drive rod 341 etc. [0086] The driven transmission mechanism 350 of the clutch assembly 300 will now be described. This mechanism comprises a casing 351 that is rotationally mounted within the wider neck portion 313 of the housing 310. The casing 351 has an opening at its first end 352 (nearest to the intermediate gear mechanism 340), the opening providing an outwardly sloped outer cone clutch driven surface 353, corresponding to the inner cone clutch drive surface of the intermediate gear mechanism 340. In the neutral position shown in Figure 2a, the two cone clutch surfaces 346, 353 have a small gap between them.
-19 - [0087] Further down the opening (away from the intermediate drive mechanism 340) is a spring holder 354 comprising a lug extending up from the bottom of the opening (towards the intermediate drive mechanism 340). The spring 348 of the intermediate drive mechanism 340 sits around the lug, so that its compression axis stays in line with the rotational axis of the drive rod 341 etc. [0088] At a second end of the casing is an interior shaft 355 provided with teeth 356 around the circumference, the teeth 356 extending along the shaft 355.
[0089] The teeth 356 of the inner shaft 355 correspond and mesh with teeth of a toothed rod 241 of the wheel drive shaft assembly 240. Hence, rotation of the casing 351 causes the toothed rod 241 to rotate. The toothed rod 241 is mounted to a connection member 242, which also mounts the wheel drive shaft 243. Hence, rotation of the casing 351 within the housing 310 causes the wheel drive shaft 243 (and hence, the wheel mounted to it) to rotate about its axis.
[0090] Figure 2b shows the clutch assembly of Figure 2a, the clutch assembly in an intermediate position, prior to forwards driving. Here, the actuator mechanism 330 has been partially retracted so that the lever 321 has been rotated in a clockwise direction by 12 degrees and so that roller 327 starts to abut against abutment surface 344. This causes the intermediate drive mechanism 340 (including the drive rod 341) to be pushed to the right, against the compression spring 348. As can be seen in Figure 2b, there is now a small gap between the first end 342 of the drive rod 341 and the end of the opening 311. As can also be seen, the inner cone clutch drive surface 346 has been moved closer to the outer cone dutch driven surface 353.
[0091] Figure 2c shows the clutch assembly of Figure 2a, the clutch assembly in a forwards driving position. Here, the actuator mechanism 330 has been further retracted so that the lever 321 has been rotated further in a clockwise direction to an angle of 26 degrees. During that motion, the roller 327 continued to push against abutment surface 344. This caused the intermediate drive mechanism 340 (including the drive rod 341) to be pushed further to the right, as shown in Figure 2c, against the compression spring 348. Hence, as can be seen in Figure 2c, there is a larger gap between the first end 342 of the drive rod 341 and the end of the opening 311. As can also he seen, the inner cone clutch -20 -drive surface 346 has been moved into driving contact with the outer cone clutch driven surface 353. In addition, the teeth of pinion gear 325 are now in contact with and meshed with the teeth of the cog wheel 345. Importantly, the pinion gear 325 meshes with the cog wheel 345 just prior (when the lever 321 is at an angle of 21 degrees) to the cone clutch surfaces 346, 353 engaging (starting at when the lever 321 is at an angle of 24 degrees and fully engaged when it is at 26 degrees).
[0992] Hence, in the position show in in Figure 2c, it can be seen that the following driving connections are now present: i) pinion gear 325 to cog wheel 345, and ii) inner cone clutch drive surface 346 to outer cone clutch driven surface 353.
[0993] This is in addition to the driving connections that already exist of: motor 210 and gearbox assembly 220 to main drive shaft 230, main drive shaft 230 to input gear 322 input gear 322 to output gear 323, - output gear 323 to pinion gear 325, - cog wheel 345 attached to inner cone clutch drive surface 346, - outer cone clutch driven surface 353 mounted on casing 351, - teeth 356 of inner shaft on casing 351, - teeth 356 meshing with toothed rod 241 of wheel drive shaft assembly 240, - wheel drive shaft assembly 240 to wheel drive interface 250, - wheel drive interface 250 to wheel 152 (not shown).
[0094] Hence, it can be seen that by providing the driving connections i) and ii) above, the motor 210 is thus drivingly connected to the wheel 152.
[0095] Figure 2d shows the clutch assembly of Figure 2a, the clutch assembly in a reverse driving position. Here, the actuator mechanism 330 has been extended from the neutral position of Figure 2a so that the lever 321 has been rotated in an anti-clockwise direction through an intermediate position to the driving position it is in in Figure 2d.
[0996] In the intermediate position, the actuator mechanism 330 has been partially extended from the neutral position in Figure 2a so that the lever 321 has been rotated in an anti-clockwise direction and so that roller 328 abuts against abutment surface 344.
-21 -This has caused the intermediate drive mechanism 340 (including the drive rod 341) to be pushed to the right, against the compression spring 348.
[0097] In the driving position of Figure 2d, the actuator mechanism 330 has been further extended so that the lever 321 has been rotated further in an anti-clockwise direction and so that roller 328 continues to push against abutment surface 344. This has caused the intermediate drive mechanism 340 (including the drive rod 341) to he pushed further to the right, as shown in Figure 2d, against the compression spring 348. Hence, as can he seen in Figure 2d, there is a large gap between the first end 342 of the drive rod 341 and the end of the opening 311. As can also be seen, the inner cone clutch drive surface 346 has been moved into driving contact with the outer cone clutch driven surface 353. In addition, the teeth of pinion gear 326 are now in contact with and meshed with the teeth of the cog wheel 345.
[0098] The same angles (hut in the other direction) apply to the stages of engagement and movement of the lever arm 321 in this reverse mode, as it does for the forwards mode described in relation to Figures 2b and 2c.
[0099] Hence, in the position show in in Figure 2d, it can be seen that the following driving connections are now present: i) pinion gear 326 to cog wheel 345, and ii) inner cone clutch drive surface 346 to outer cone clutch driven surface 353.
[00100] This is in addition to the driving connections that already exist of: - motor 210 and gearbox assembly 220 to main drive shaft 230, - main drive shaft 230 to input gear 322 - input gear 322 to output gear 324, - output gear 324 to pinion gear 326, - cog wheel 345 attached to inner cone clutch drive surface 346, outer cone clutch driven surface 353 mounted on casing 351, teeth 356 of inner shaft on casing 351, teeth 356 meshing with toothed rod 241 of wheel drive shaft assembly 240, wheel drive shaft assembly 240 to wheel drive interface 250, wheel drive interface 250 to wheel 152 (not shown).
-22 - [00101] Hence, it can be seen that by providing the driving connections i) and it) above, the motor 210 is thus drivingly connected to the wheel 152.
[00102] Importantly, as the pinion gears 325, 326 are mounted on opposite sides of the cog wheel 345 they cause the cog wheel 345 to rotate in different directions. Hence, in Figure 2c, the pinion gear 325 causes the cog wheel 345 to rotate in a direction that causes forwards movement of the wheel 152, and in Figure 2d, the pinion gear 326 causes the cog wheel 345 to rotate in a direction that causes reverse movement of the wheel 152.
[00103] Prior to use, the motor 210 is turned off and the actuator mechanism 330 is in the neutral position (as in Figure 2a).
[00104] When it is desired to drive the wheel 152 of the aircraft in a forwards direction, for example at a speed of up to 20 knots, two actions happen: i) the motor 210 is turned on, and ii) the actuator mechanism 330 is retracted to the position of Figure 2c (through the intermediate position of Figure 26). These two actions could happen in any order. For example, in a pre-engagement test mode, the motor 210 could he turned on, causing the input gear 220, output gears 323, 324 and pinion gears 325, 326 to rotate, prior to movement of the actuator mechanism 330. When both actions have occurred, due to the driving connections explained above, the wheel 152 is then driven in a forwards direction.
[00105] When it is no longer desired to drive the wheel 152 of the aircraft in a forwards direction, the actuator mechanism 330 is retracted to the neutral position (which enables the biasing action of the compression spring 348 to return the intermediate drive mechanism 340 to the neutral position of Figure 2a) and/or the motor 210 is turned off.
[00106] When it is desired to drive the wheel 152 of the aircraft in a reverse direction, two actions happen: i) the motor 210 is turned on (if it is not on already), and ii) the actuator mechanism 330 is extended to the position of Figure 2d. These two actions could happen in any order. When both actions have occurred, due to the driving connections explained above, the wheel 152 is then driven in a reverse direction.
[00107] When it is no longer desired to drive the wheel 152 of the aircraft in a reverse direction, the actuator mechanism 330 is extended to the neutral position (which enables -23 -the biasing action of the compression spring 348 to return the intermediate drive mechanism 340 to the neutral position of Figure 2a) and/or the motor 210 is turned off.
[00108] Figure 3 shows an enlarged view of a first alternative trailing lever arm and wheel axle arrangement and drive assembly 200'. Here, instead of the gearbox assembly 220 being inside the lever arm 130 (as for the drive assembly 200), both the motor 210 and gearbox assembly 220 are located externally to the lever arm 130, adjacent to the top of the lever arm 130. Here, the layout of the motor 210 and gearbox assembly 220 are both not constrained by the tube diameter of the lever arm 130.
[00109] Figure 4 shows an enlarged view of a second alternative trailing lever arm and wheel axle arrangement and drive assembly 200". Here, instead of the gearbox assembly 220 being inside the lever arm 130 (as for the drive assembly 200), both the motor 210 and gearbox assembly 220 are located externally to the lever arm 130, adjacent to the top of the lever arm 130 (like in Figure 3). In addition, the clutch assembly 300 is located externally to the lever arm 130, adjacent to the bottom of the lever arm 130. Here, the layout of the motor 210, gearbox assembly 220 and clutch assembly 300 are all not constrained by the tube diameter of the lever arm 130.
[00110] Figure 5 shows an enlarged view of a third alternative trailing lever aim and wheel axle arrangement and drive assembly 200'''. Here, instead of the gearbox assembly 220 being inside the lever arm 130 (as for the drive assembly 200), both the motor 210 and gearbox assembly 220 are located externally to the lever arm 130, adjacent to the top of the lever arm 130 (like in Figures 3 and 4). In addition, the clutch assembly 300 is replaced by a bevel gear arrangement including two bevels 501, 502 that are permanently engaged with each other. The bevel arrangement connects the main drive shaft 230 and wheel drive shaft assembly 240. In this drive assembly 200"', the change of direction of wheel is achieved by reversing the motor 210 or by using the gearbox assembly 220. The arrangement includes a simple clutch (not shown) to ensure disengagement of the motor 210 and/or gearbox assembly 220 from the wheel drive shaft assembly 240. That clutch could be located at either end of the main drive shaft 230. This arrangement is shown in relation to the left wheel axle 141, for clarity. Here, the layout of -24 -the motor 210 and gearbox assembly 220 are both not constrained by the tube diameter of the lever arm 130.
[00111] Figure 6 shows an enlarged view of a fourth alternative trailing lever arm and wheel axle arrangement and drive assembly 200"". Here, instead of the gearbox assembly 220 being inside the lever arm 130 (as for the drive assembly 200), both the motor 210 and gearbox assembly 220 are located externally to the lever arm 130, adjacent to the top of the lever arm 130 (like in Figures 3, 4 and 5). In addition, the clutch assembly 300 is located externally to the lever arm 130, adjacent to the bottom of the lever arm 130 (like in Figure 4). In addition, the clutch assembly 300 is used to drive a wheel drive shaft assembly in each side of the wheel axle 141, 142 (2406, 240a respectively). This could be done in two ways.
[00112] The first way is by driving the two wheel drive shaft assemblies 240a, 2406 in the same direction as each other so that they are both driven forwards or both driven backwards. This selection of forwards/reverse could be done by the motor 210 or gearbox assembly 220.
[00113] The second way is by having one wheel drive shaft assembly, say 240a, able to be driven forwards and the other one wheel drive shaft assembly, say 240b, able to be driven backwards. The control of which of the two wheel drive shaft assemblies is driven is done by the clutch assembly 300.
[00114] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.
[00115] In some embodiments, it is not required to use a trailing lever arm 130.
Instead, the wheel axle 140 may be mounted to a conventional shock strut.
[00116] In some embodiments, the suspension arrangement (main fitting and slider potions of main strut 110) may be different, such as an arrangement where the slider portion of the main strut 110 is directly connected to the lever arm 130 (i.e. there is no strut 134).
-25 - [00117] As one alternative to the Figures 4, 5 and 6 embodiments and variants, the arrangement could have the motor 210 and gearbox assembly 220 located as shown in Figure lb. [00118] In some embodiments, it is not required to have either one (or both) of the motor 210 and gearbox assembly 220 located internally of the lever arm 130, or even adjacent to the upper end of the lever arm 130.
[00119] The motor 210 may he an electric motor, hydraulic motor or any other
suitable motor.
[00120] The clutch cone surfaces 346, 353 may be replaced with two corresponding gear elements.
[00121] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should he construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.
[00122] It should be noted that throughout this specification, "or" should be interpreted as "and/or".

Claims (39)

  1. -26 -CLAIMSI. A landing gear drive system clutch assembly comprising: i) a drive gear assembly for receiving driving torque from a landing gear drive motor, ii) a driven transmission assembly for transmitting driving torque to a wheel of a landing gear, and iii) an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly.
  2. 2. A landing gear drive system clutch assembly as claimed in claim 1, wherein movement of the drive gear assembly towards its engaged position causes the intermediate gear assembly to move towards its engaged position.
  3. 3. A landing gear drive system clutch assembly as claimed in claim 2, wherein movement of the drive gear assembly towards its engaged position pushes the intermediate gear assembly to move towards its engaged position.
  4. -27 - 4. A landing gear drive system clutch assembly as claimed in claim 3, wherein during movement of the drive gear assembly towards its engaged position, a non-torque transmitting part of the drive gear assembly pushes against a non-torque transmitting part of the intermediate gear assembly.
  5. 5. A landing gear drive system clutch assembly as claimed in claim 4, wherein the non-torque transmitting part of the drive gear assembly and the intermediate gear assembly form a roller and abutment surface pair.
  6. 6. A landing gear drive system clutch assembly as claimed in claim 5, wherein the non-torque transmitting part of the drive gear assembly is a roller and the non-torque transmitting part of the intermediate gear assembly is an abutment surface.
  7. 7. A landing gear drive system clutch assembly as claimed in any preceding claim, wherein movement of the drive gear assembly towards its disengaged position causes the intermediate gear assembly to move towards its disengaged position.
  8. 8. A landing gear drive system clutch assembly as claimed in claim 7, wherein the intermediate gear assembly is biased towards its disengaged position by a biasing element.
  9. 9. A landing gear drive system clutch assembly as claimed in any preceding claim, wherein the intermediate gear assembly comprises a clutch surface for engaging with a corresponding clutch surface on the driven transmission assembly.
  10. 10. A landing gear drive system clutch assembly as claimed in claim 9, wherein the intermediate gear assembly clutch surface is a conic surface and the driven transmission assembly clutch surface is a corresponding conic surface.
  11. 11. A landing gear drive system clutch assembly as claimed in any preceding claim, wherein the drive gear assembly comprises an input gear for receiving driving torque from a landing gear drive motor, and two pinion gears both in driving torque connection -28 -with the input gear, and both arranged to be connected to the intermediate gear assembly so as to transmit driving torque to the intermediate gear assembly.
  12. 12. A landing gear drive system clutch assembly as claimed in claim 1 1, wherein the two pinion gears are mounted on either side of a rotation axis of the intermediate gear assembly, on a pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the intermediate gear assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the intermediate gear assembly.
  13. 13. A landing gear drive system clutch assembly as claimed in claim 12, wherein the pivotable lever is moveable between (i) a first pinion gear engaged position, in which the first pinion gear is in driving torque connection with the intermediate gear assembly, and (ii) a second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the intermediate gear assembly, through (iii) a neutral position, in which neither of the pinion gears are in driving torque connection with the intermediate gear assembly.
  14. 14. A landing gear drive system comprising the landing gear drive system clutch assembly of any preceding claim, and further comprising a wheel drive shaft and wherein the driven transmission assembly is arranged to be connected to the wheel drive shaft so as to transmit driving torque to the wheel of a landing gear.
  15. 15. A landing gear drive system as claimed in claim 14, wherein the wheel drive shaft is configured for location within a landing gear wheel axle.
  16. 16. A landing gear drive system as claimed in claim 14 or claim 15, wherein the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the intermediate gear assembly and wherein movement of the drive gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft.
  17. -29 - 17. A landing gear drive system as claimed in any of claims 14 to 16, wherein the intermediate gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly and wherein movement of the intermediate gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft.
  18. 18. An aircraft landing gear comprising: i) a main strut having a first end region and a second opposite end region, the main strut being for connection at its first end region to an aircraft, ii) a lever arm having a first end region and a second opposite end region, the lever arm being pivotally connected at its first end region to the second end region of the main strut, iii) a wheel axle mounting one or more wheels, the wheel axle being connected transversely to the lever arm in the second end region of the lever arm, and iv) a drive system, the drive system comprising: - a wheel drive shaft for driving rotation of the one or more wheels, the wheel drive shaft being located within the wheel axle, - a main drive shaft for driving rotation of the wheel drive shaft, the main drive shaft being located within the lever arm, and - a motor and/or gearing assembly for driving rotation of the main drive shaft, the motor or gearing assembly being located adjacent to the first end region of the lever arm.
  19. 19. An aircraft landing gear as claimed in claim 18, wherein the motor is located within the first end region of the lever arm.
  20. 20. An aircraft landing gear as claimed in claim 18, wherein the motor is located externally at the first end region of the lever arm.
  21. -30 - 21. An aircraft landing gear as claimed in any of claims 18 to 20, wherein the gearing assembly is located adjacent to the first end region of the lever arm.
  22. 22. An aircraft landing gear as claimed in claim 2 1, wherein the gearing assembly is located within the first end region of the lever arm.
  23. 23. An aircraft landing gear as claimed in claim 21, wherein the gearing assembly is located externally at the first end region of the lever arm.
  24. 24. An aircraft landing gear as claimed in any of claims 18 to 23, wherein the lever arm is a trailing link extending in an aft direction from the main strut, in relation to an aircraft flight direction.
  25. 25. An aircraft landing gear as claimed in any of claims 18 to 24, wherein the wheel axle intersects with the lever arm to provide an intersection region of the wheel axle and second end region of the lever arm.
  26. 26. An aircraft landing gear as claimed in claim 25, wherein the drive system further comprises a clutch assembly for controlling a driving connection of the main drive shaft and the wheel drive shaft, the clutch assembly being located in the intersection region of the second end region of the lever arm and the wheel axle.
  27. 27. An aircraft landing gear as claimed in any of claims 18 to 25, wherein the aircraft landing gear comprises a clutch assembly as claimed in any of claims I to 13 or any of claims 32 to 36.
  28. 28. A landing gear drive system comprising: i) a wheel drive shaft configured to be located within a landing gear wheel axle, and ii) a clutch assembly, the clutch assembly comprising: -31 - - a drive gear assembly for receiving driving torque from a landing gear drive motor, and - a driven transmission assembly, capable of driving torque connection to the wheel drive shaft to provide driving torque to a wheel of a landing gear, wherein the drive gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the driven transmission assembly, and wherein the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly and wherein movement of the drive gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft.
  29. 29. A landing gear drive system as claimed in claim 28, wherein the clutch assembly further comprises an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly.
  30. 30. A landing gear drive system as claimed in claim 29, wherein the intermediate gear assembly comprises an output element for transmitting driving torque to a corresponding -32 -input element of the driven transmission assembly and wherein movement of the intermediate gear assembly towards its engaged position comprises movement of the output element along the direction of the axis of the wheel drive shaft.
  31. 31. A landing gear drive system as claimed in any of claims 28 to 30, wherein the clutch assembly is as claimed in any of claims 1 to 13 or claims 32 to 36.
  32. 32. A landing gear drive system clutch assembly comprising: i) a drive gear assembly for receiving driving torque from a landing gear drive motor, ii) a driven transmission assembly for transmitting driving torque to a wheel of a landing gear, and wherein the drive gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the driven transmission assembly, and wherein the drive gear assembly comprises an input gear for receiving driving torque from a landing gear drive motor, and two pinion gears for transmitting driving torque to the driven transmission assembly, wherein the input gear is capable of driving torque connection with the pinion gears, and wherein the two pinion gears are mounted on either side of a rotation axis of the driven transmission assembly, on a pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the driven transmission assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the driven transmission assembly.
  33. -33 - 33. A landing gear drive system clutch assembly as claimed in claim 32, wherein the pivotable lever is moveable between a first pinion gear engaged position, in which the first pinion gear is in driving torque connection with the driven transmission assembly, and second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the driven transmission assembly, through a neutral position, in which neither of the pinion gears are in driving torque connection with the driven transmission assembly.
  34. 34. A landing gear drive system clutch assembly as claimed in claim 32 or 33, wherein the clutch assembly further comprises an intermediate gear assembly, for receiving driving torque from the drive gear assembly and transmitting driving torque to the driven transmission assembly, wherein the drive gear assembly is moveable in relation to the intermediate gear assembly between the disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and the engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, and wherein the intermediate gear assembly is moveable in relation to the driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly.
  35. 35. A landing gear drive system clutch assembly as claimed in claim 34, wherein the two pinion gears are mounted on either side of a rotation axis of the intermediate gear assembly, on the pivotable lever, wherein movement of the pivotable lever in a first direction causes a first pinion gear to move towards the intermediate gear assembly and movement of the pivotable lever in a second direction causes a second pinion gear to move towards the intermediate gear assembly.
  36. 36. A landing gear drive system clutch assembly as claimed in claim 35, when dependent on claim 33, wherein the pivotable lever is moveable between the first pinion -34 -gear engaged position, in which the first pinion gear is in driving torque connection with the intermediate gear assembly, and the second pinion gear engaged position, in which the second pinion gear is in driving torque connection with the intermediate gear assembly, through the neutral position, in which neither of the pinion gears are in driving torque connection with the intermediate gear assembly.
  37. 37. A method of operating a landing gear drive system, the method comprising the steps of: i) providing driving torque from a landing gear drive motor to a drive gear assembly, ii) moving the drive gear assembly in relation to an intermediate gear assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the intermediate gear assembly, and an engaged position in which the drive gear assembly is in driving torque connection with the intermediate gear assembly, iii) moving the intermediate gear assembly in relation to a driven transmission assembly between a disengaged position, in which the intermediate gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the intermediate gear assembly is in driving torque connection with the driven transmission assembly, and iv) providing driving torque from the driven transmission assembly to a wheel of a landing gear.
  38. 38. A method of operating a landing gear, the method comprising the steps of: i) providing driving torque from a landing gear drive motor to a drive gear assembly, ii) moving the drive gear assembly in relation to a driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and an engaged position in which the -35 -drive gear assembly is in driving torque connection with the driven transmission assembly, and iii) providing driving torque from the driven transmission assembly to a wheel drive shaft located within a landing gear wheel axle of the landing gear, and wherein the drive gear assembly comprises an output element for transmitting driving torque to a corresponding input element of the driven transmission assembly, and wherein the movement of the drive gear assembly between the disengaged and engaged positions comprises movement of the output element along the direction of the axis of the wheel drive shaft.
  39. 39. A method of operating a landing gear drive system, the method comprising the steps of, in a forward driving mode: i) providing driving torque from a landing gear drive motor to a drive gear assembly, the drive gear assembly comprising an input gear for receiving driving torque from the landing gear drive motor, ii) moving the drive gear assembly in relation to a driven transmission assembly between a disengaged position, in which the drive gear assembly is not in driving torque connection with the driven transmission assembly, and a forwards engaged position in which a first of two pinion gears of the drive gear assembly is in driving torque connection with the driven transmission assembly, iii) providing driving torque from the driven transmission assembly to a wheel of a landing gear, and, in a reverse driving mode: i) providing driving torque from the landing gear drive motor to the input gear of the drive gear assembly, -36 -ii) moving the drive gear assembly in relation to the driven transmission assembly between the disengaged position and a reverse engaged position in which a second of two pinion gears of the drive gear assembly is in driving torque connection with the driven transmission assembly, iii) providing driving torque from the driven transmission assembly to a wheel of a landing gear, wherein the two pinion gears are mounted on either side of a rotation axis of the driven transmission assembly, on a pivotable lever, wherein the step of moving the drive gear assembly between the disengaged position and the forwards engaged position comprises movement of the pivotable lever in a first direction causing the first pinion gear to move towards the driven transmission assembly and wherein the step of moving the drive gear assembly between the disengaged position and the reverse engaged position comprises movement of the pivotable lever in a second direction causing the second pinion gear to move towards the driven transmission assembly.
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Cited By (1)

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US20230339606A1 (en) * 2022-04-25 2023-10-26 Safran Landing Systems Canada Inc. Augmenter for a landing gear drive system

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EP2664507A1 (en) * 2012-05-15 2013-11-20 Goodrich Corporation Systems and method for reflected inertia parking brake
EP2666717A2 (en) * 2012-05-03 2013-11-27 Goodrich Corporation Systems and methods for aircraft braking and taxiing
WO2014023939A1 (en) * 2012-08-08 2014-02-13 Airbus Operations Limited Landing gear drive systems
WO2014023941A1 (en) * 2012-08-08 2014-02-13 Airbus Operations Limited Landing gear drive systems
US20140263832A1 (en) * 2013-03-12 2014-09-18 Messier-Bugatti-Dowty Multifunction device for an undercarriage
GB2517396A (en) * 2013-05-13 2015-02-25 Airbus Operations Ltd Landing gear drive systems
WO2015040363A1 (en) * 2013-09-18 2015-03-26 Airbus Operations Limited Drive system for aircraft landing gear
CN207292389U (en) * 2017-09-14 2018-05-01 曾保祥 A kind of aircraft

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EP2666717A2 (en) * 2012-05-03 2013-11-27 Goodrich Corporation Systems and methods for aircraft braking and taxiing
EP2664507A1 (en) * 2012-05-15 2013-11-20 Goodrich Corporation Systems and method for reflected inertia parking brake
WO2014023939A1 (en) * 2012-08-08 2014-02-13 Airbus Operations Limited Landing gear drive systems
WO2014023941A1 (en) * 2012-08-08 2014-02-13 Airbus Operations Limited Landing gear drive systems
US20140263832A1 (en) * 2013-03-12 2014-09-18 Messier-Bugatti-Dowty Multifunction device for an undercarriage
GB2517396A (en) * 2013-05-13 2015-02-25 Airbus Operations Ltd Landing gear drive systems
WO2015040363A1 (en) * 2013-09-18 2015-03-26 Airbus Operations Limited Drive system for aircraft landing gear
CN207292389U (en) * 2017-09-14 2018-05-01 曾保祥 A kind of aircraft

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20230339606A1 (en) * 2022-04-25 2023-10-26 Safran Landing Systems Canada Inc. Augmenter for a landing gear drive system

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