A drive system for an actuator, and actuator mounting for an aircraft control surface.

Abstract

A drive system for an actuator, and actuator mounting for an aircraft control surface. It is a drive system (2) for an actuator comprising the first and second motors (4, 6), and the first and second input rods (14, 16) connected to be actuated by the respective first and second motors (4, 6). Each of the first and second input rods (14, 16) comprises a first overlapping clutch (46a, 46b), configured to rotate with the input rod (14, 16) in a first direction, and a second overlapping clutch (46c, 46d), configured to rotate with the input rod (14, 16) in a second direction.A first drive gear (60) is configured to be driven by either of the first overlapping clutches (46a, 46b) and a second drive gear (62) is configured to be driven by either of the second overlapping clutches (46c, 46d), and an output clutch (64) and an output rod (18) are arranged to be driven by the first drive gear (60) in a first operating mode of the drive system (2) and to be driven by the second drive gear (62) in a second operating mode of the drive system (2).

Description

26 A drive system for an actuator, and actuator mounting for an aircraft control surface. TECHNICAL FIELD

[001] The present invention relates to an electromechanical drive system with dual electric motor drive, in particular for use as or as part of an electrically driven actuator or actuation system in an aircraft. FUNDAMENTALS

[002] Actuators are used in various parts of aircraft systems to move mechanical elements of the aircraft, for example, control surfaces, between two positions. This actuation is often driven, directly or indirectly, by engines.

[003] Actuators and actuation systems in aircraft are often considered critical to safety, so secondary or redundant actuation channels must be provided in case of failure of a primary actuation channel. It is also necessary that both the primary and secondary systems be robust.

[004] In aircraft systems, there is an additional need for any actuator and associated drive systems to be compact for packaging reasons and to be lightweight. It is also desirable that the actuators and drive systems have the lowest possible complexity, which can reduce the chance of failure and reduce maintenance requirements. SUMMARY

[005] In this disclosure, a dual-motor electric drive system is provided that provides redundancy against motor drive channel failures and facilitates dual-channel electric motor drives in active-active (driving both motors) or active-standby (driving one motor) modes, in addition to being robust, packaged in Petition 870230049480, dated 09 / 06 / 2023, page 5 / 49 / 26 in an efficient manner and have reduced complexity compared to other provisions.

[006] According to a first aspect of the present disclosure, a drive system is provided for an actuator or actuation system, wherein the drive system comprises first and second motors and first and second input rods connected to be driven by the respective first and second motors. Each of the first and second input rods comprises a first overlapping clutch, configured to rotate with the input rod in a first direction, and a second overlapping clutch, configured to rotate with the input rod in a second direction. The drive system further comprises a first driving gear configured to be driven by either of the first overlapping clutches and a second driving gear configured to be driven by either of the second overlapping clutches.The drive system further comprises an output rod and an output clutch associated with the output rod, wherein the output clutch and the output rod are arranged to be driven by the first driving gear in a first operating mode of the drive system and to be driven by the second driving gear in a second operating mode of the drive system.

[007] In active-active mode, both motors are active and the drive system combines the input of the motors into a single output, so that an output torque is the sum of the torque supplied by each motor.

[008] In an active-standby mode, the drive system provides the torque supplied by an active motor to the output, while allowing another standby motor to remain stationary. If the input to the active motor fails, the drive system connects the input of the standby motor to the output. In the event of such a failure mode, the drive system will activate the Petition 870230049480, dated 09 / 06 / 2023, page 6 / 49 / 26 output regardless of whether the input failure is due to a mechanical lock within the motor or a loss of power supplied to the motor. The drive system is therefore robust against a failure of the motor or the associated electrical drive channel.

[009] The described functionality of the drive system is provided if the drive system is commanded to drive in the clockwise or counterclockwise direction of the output rotation.

[0010] The drive system is a significant improvement over drive system arrangements that may use a differential gearbox to couple two motor drive channels to a single output. Such a differential arrangement may have much greater complexity, for example, requiring additional electrically actuated brakes to ground the differential gearbox, additional electrical interfaces, additional electrical power, and additional control signals.

[0011] In another embodiment of the drive system described above, the output rod defines a geometric axis of rotation and the output clutch comprises a driven clutch piece connected to the output rod and first and second drive clutch pieces that are moved axially into and out of engagement with the driven clutch piece.

[0012] In another embodiment of any of the above items, the first and second drive gears are positioned adjacent to a respective first and second part of the drive clutch, each of the first and second drive gears and parts of the drive clutch comprising a plurality of ramp elements and a plurality of rolling elements are positioned between the ramp elements of the adjacent first and second drive gears and parts of the drive clutch.

[0013] In another form of any of the above, the Petition 870230049480, dated 09 / 06 / 2023, page 7 / 49 / 26 plurality of rolling elements includes a plurality of ball bearings.

[0014] In another embodiment of any of the foregoing, the drive system further comprises first and second bearing cages, each bearing cage comprising a plurality of openings, the plurality of ball bearings received within the plurality of openings.

[0015] In another embodiment of any of the foregoing, the output clutch comprises a conical clutch comprising a pair of male conical elements and a pair of female conical elements, one of the male conical elements in frictional contact with one of the female conical elements in the first mode of operation, and the other of the male conical elements in frictional contact with the other of the female conical elements in the second mode of operation.

[0016] In another embodiment of any of the above, the pair of male conical elements forms the driven part of the clutch and the pair of female conical elements forms the first and second parts of the drive clutch.

[0017] In another embodiment of any of the above, the first and second input rods define geometric axes of rotation that are parallel to the geometric axis of the output rod.

[0018] In another embodiment of any of the foregoing, each of the first overlapping clutches comprises gear teeth formed around an outer periphery, the gear teeth meshing with the gear teeth of the first driving gear and each of the second overlapping clutches comprises gear teeth formed around an outer periphery, the gear teeth meshing with the gear teeth of the second driving gear. Petition 870230049480, dated 09 / 06 / 2023, page 8 / 49 / 26

[0019] In another embodiment of any of the foregoing, each of the first overlapping clutches and each of the second overlapping clutches comprises a flap clutch, each having a plurality of flap elements in contact with the respective input rod.

[0020] In another embodiment of any of the foregoing, the drive system further comprises a dynamic drag clutch comprising a brake wheel connected to the output rod and at least one drag pin in contact with the brake wheel.

[0021] In another embodiment of any of the above, the drive system further comprises an epicyclic gearbox, the output rod arranged to drive an input of the epicyclic gearbox.

[0022] In any other embodiment of the foregoing, the first and second motors comprise the same maximum speed and torque capacity and / or the same speed-to-torque ratio.

[0023] According to another aspect of the present disclosure, an actuator assembly is provided for an aircraft control surface, the actuator assembly comprising an actuator and a drive system according to any of the embodiments above, the drive system connected to actuate the actuator.

[0024] In another embodiment of the above, the actuator is a linear actuator.

[0025] These and other features of the disclosure can be better understood from the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 shows a side view of a drive system according to an aspect of the disclosure.

[0027] Figure 2 shows a front view of the drive system of Figure 1. Petition 870230049480, dated 09 / 06 / 2023, page 9 / 49 / 26

[0028] Figure 3 shows a plan view of the drive system of Figures 1 and 2 along line A.

[0029] Figure 4 shows a partial and detailed view of a part of the drive system of Figure 3.

[0030] Figure 5 shows a partial and detailed view of a part of the drive system of Figure 4.

[0031] Figure 6 shows another partial and detailed view of another part of the drive system of Figure 3.

[0032] Figure 7 shows an isolated perspective view of an output rod 18 of the drive system of Figure 3.

[0033] Figure 8 shows an isolated perspective view of a drive gear of the drive system of Figure 3.

[0034] Figure 9 shows a front cutaway view of the drive system of Figure 2 along line B.

[0035] Figure 10 shows a partial cutaway side view of the drive system of Figure 9 along line C.

[0036] Figure 11 shows a front cutaway view of the drive system of Figures 1 and 3 along line D.

[0037] Figure 12 shows another partial and detailed view of another part of the drive system of Figure 3.

[0038] Figure 13 shows another partial and detailed view of another part of the drive system of Figure 3.

[0039] Figure 14 shows a set of aircraft control surfaces. DETAILED DESCRIPTION OF THE DRAWINGS

[0040] Figures 1 and 2 show side and front views of an electromechanical actuator drive system comprising two motors connected to a single common drive output. The drive system 2 comprises first and second electric motors 4, 6 Petition 870230049480, dated 09 / 06 / 2023, page 10 / 49 / 26 connected to the respective inputs of a first combined input gearbox 8. The combined input gearbox combines the torque input of the motors to provide a single output. The system also includes a second gearbox 10 connected to the output of the combined input gearbox 8, which provides the drive system output 12.

[0041] The drive system 2 is configured so that either of the first or second motors 4, 6 can drive the output of the drive system 12 in either direction of rotation, depending on the operating mode of the drive system 2, to provide two-way drive actuation. Furthermore, the same drive system 2 can be operated so that the first and second motors 4, 6 drive the output of the drive system 12 together to provide combined torque in either direction of rotation.

[0042] Figure 3 is a plan view in section of the drive system 2 along line A of Figures 1 and 2, showing internal features of the first and second gearboxes 8, 10. The first and second motors 4, 6 drive the respective first and second input rods 14, 16 positioned in the first gearbox 8. The first and second input rods 14, 16 rotate around the geometric axes X and Y. The first and second input rods 14, 16 in turn drive an output rod 18 of the first gearbox 8 around a geometric axis of rotation Z. The output rod 18 is connected to the second gearbox 10 which, in turn, drives the output of the drive system 12.

[0043] Figure 4 is a partial cutaway view of the drive system 2 of Figure 3 which shows in more detail the first motor 4 and the first input rod 14 of the first gearbox 8. The first gearbox 8 comprises a receiver socket 20 in which the Petition 870230049480, dated 09 / 06 / 2023, page 11 / 49 / 26 first motor 4 is received. The receiving socket 20 is defined by a socket wall extending in the direction of the geometric X axis. The receiving socket 20 is shaped correspondingly to an outer periphery 22 of the motor 4, and the motor 4 is disposed in the receiving socket 20 in a press fit. The motor comprises a seal 24 positioned in a circumferential slot in the outer periphery 22, which seals the outer periphery 24 and the socket wall. The outer periphery 22 of the motor 4 is generally cylindrical, and the socket wall and the seal 24 are correspondingly annular.

[0044] The first motor 4 comprises a motor drive shaft 26 that is connected to the first input rod 14 of the first gearbox 8. The first input rod 14 comprises a tubular form formed by an annular wall around the geometric axis of rotation X of the input rod 14. The input rod 14 extends axially from a first connecting end 28 adjacent to the motor to a second distal end 30. The connecting end 28 of the input rod 14 comprises an opening 32 circumscribed by a radially contracted portion of the annular wall. The radially contracted portion is shaped correspondingly to the motor drive shaft 26, which is received at the opening 32.

[0045] The motor drive shaft 26 is connected to the input rod 14, so that the motor drive shaft 26 can drive the first input rod 14 in any direction of rotation. The motor drive shaft 26 and the opening 32 may comprise a splined or keyed fitting to provide the drive connection and engagement between the motor drive shaft 26 and the input rod 14.

[0046] The first gearbox 8 comprises a wall 34 defining an interior space including a first cavity 40, the first input rod 14 received in the first cavity 40. The wall of the gearbox Petition 870230049480, dated 09 / 06 / 2023, page 12 / 49 / 26 Gear 34 comprises protrusions 36 on an inner periphery thereof to receive the input rod 14. The input rod 14 comprises bearings 38 to allow rotation of the input rod 14 in place in the cavity 40. The bearings 38 comprise raceway rolling elements, the raceways cooperating with the wall of the input rod 14 and with the protrusions 36 of the first gearbox 8. The input rod 14 comprises two pluralities of axial bearings, respectively positioned at each of the first and second ends 28, 30 of the input rod 14, to support the input rod 14 along its entire length.

[0047] Returning to Figure 3, the second motor 6 is connected to the second input rod 16 of the first gearbox 8 in the same way as the first motor 4 and the first input rod 14, and the second input rod 16 is similarly positioned in a second cavity 42 of the first gearbox 8. The second motor 6 and the second input rod 16 comprise all the same features described above in relation to the first motor 4 and the first input rod 14. In the illustrated example, the two sets of features are substantially identical.In particular, the first and second motors 4, 6 in the example shown comprise the same type of motor, with the same dimensions and drive characteristics, so that the two motors 4, 6 can each independently provide all the necessary drive for the system 2. The drive characteristic of each motor can be defined as the maximum speed and torque capacity of the motor and / or the ratio between speed and torque output of the motor.

[0048] Alternatively, the second motor 6 may be smaller and / or have a different drive characteristic than the first motor 4, which may reduce the overall space and weight while still allowing the second motor 6 to act as a backup or auxiliary for the first motor 4. Petition 870230049480, dated 09 / 06 / 2023, page 13 / 49 / 26

[0049] The output rod 18 is received in a third cavity 44 in the first gearbox 8. The output rod 18 is centrally located in the first gearbox 8, with the two input rods 14, 16 arranged on opposite sides laterally from the output rod 18. The first and second cavities 40, 42 that receive the input rods 14, 16 are arranged on opposite sides laterally from the third cavity 44. The first, second and third cavities 40, 42, 44 are connected to each other to form a single interior space, circumscribed by the wall 34 of the first gearbox 8. The wall 34 defines a substantially airtight space, to better retain any lubricant within the drive system 2. The first, second and third cavities 40, 42, 44 are fluidly connected, allowing the lubricant to flow substantially within the entire interior space.The interiors of the first and second gearboxes 8, 10 can also be fluid-connected, so that the lubricant is shared between the interiors and unnecessary seals can be avoided.

[0050] The first and second input rods 14, 16 are each actuatingly connected to the output rod 18 by means of a plurality of overlapping clutches 46a-d positioned on each of the input rods 14, 16. Each of the overlapping clutches 46a-d is configured to rotate with the respective input rods 14, 16 when the shaft rotates in one direction of rotation (a driving direction) and to allow free movement of the input rod 14, 16 in another direction of rotation (an overtaking direction). The overlapping clutches 46a-d thus transfer torque from the input rod to the output rod 18 only in one of the two directions of rotation.

[0051] Figure 5 is a partial detailed view showing a first overlapping clutch 46a of the first input rod 14 in more detail. The overlapping clutch 46a comprises an annular body 48 Petition 870230049480, dated 09 / 06 / 2023, page 14 / 49 / 26 involving and coaxial with the first input rod 14. The annular body comprises projections 50 that extend axially outward from it in each direction. The projections define bearing recesses on either of the axial sides of the overlapping clutch 46a, in which the axial bearings 52 are received. The bearing races cooperate with the 50 lobes and with a surface of the first input rod 14, supporting the annular body 48 on either of the axial sides while allowing free rotation of the slip clutch 46a around the input rod 14. The slip clutch 46a comprises a gear portion 54 with a plurality of gear teeth arranged around an outer circumference of the annular body 48 to mesh with a drive gear of the output rod 18, as will be described further below.

[0052] Each of the first and second input rods 14, 16 comprises the respective first overlapping clutches 46a, 46b and the second overlapping clutches 46c, 46d, each comprising all the features described above in relation to the first overlapping clutch 46a on the first input rod 14. Each of the first overlapping clutches 46a, 46b are axially spaced from the respective second overlapping clutches 46c, 46d along the input rods 14, 16, with the first overlapping clutches 46a, 46b positioned towards the connecting end 28 of the input rods 14, 16, and the second overlapping clutches 46c, 46d generally towards the distal end 30. The first overlapping clutches 46a, 46b are configured to engage or allow free movement of the input rod 14, 16 in different directions of rotation for the second overlapping clutches 46c, 46d.That is, each of the first overlapping clutches 46a, 46b engages with the input rod 14, 16 in a first direction of rotation (e.g., clockwise) of the input rod 14, 16 and freewheels relative to the input rod 14, 16 in a second direction. Petition 870230049480, dated 09 / 06 / 2023, page 15 / 49 / 26 of rotation (for example, a counter-clockwise direction). Each of the second overlapping clutches 46c, 46d engages with the input rod 14, 16 in the second direction of rotation and freewheels relative to the input rod 14, 16 in the first direction of rotation. The first and second overlapping clutches 46b, 46d of the second input rod 16 are aligned in an axial direction with the first and second overlapping clutches 46a, 46c of the first input rod 14, with the aligned overlapping clutches 46a-d sharing the same direction of rotation.

[0053] In the example shown, the overlapping clutches 46a-d comprise the first and second flap clutches, each comprising a plurality of flap elements 56. The flap elements 56 of the first and second flap clutches 46a-d are positioned within the respective outer race of each of the overlapping clutches. The flap elements 56 are connected to an inner surface 58 of the annular body 48, so that they are able to flex in place between a sliding position and an actuating position. A contact surface of each of the tab elements 56 contacts the wall of the input rod 14, 16. When the input rod 14, 16 rotates in the first direction of rotation, the tab elements 56 of the first tab clutch 46a, 46b are forced into an actuation position and form an actuation engagement between the input rod 14, 16 and the annular body 48.When the input rod 14, 16 rotates in the second direction of rotation, the flap elements 56 of the first flap clutch 46a, 46b can return to a sliding position and the input rod 14, 16 rotates freely within a sliding contact of the expanding elements 56. The flap elements 56 in the second flap clutch 46c, 46d are positioned in a circumferentially mirrored direction to the flap elements 56 of the first flap clutch 46a, 46b. In the second spring clutch 46c, 46d, the spring elements 56 function in the same way as those of the first. Petition 870230049480, dated 09 / 06 / 2023, page 16 / 49 / 26 spring clutch 46a, 46b, except in opposite rotational directions.

[0054] Figure 6 is a partial cutaway view of the drive system 2 of Figure 3 showing the characteristics of the output rod 18 in greater detail. The output rod 18 comprises first and second drive gears 60, 62, each configured to receive torque from either of the first and second input rods 14, 16. The first and second drive gears 60, 62 are each configured to rotate freely around the output rod 18 in one mode of operation and to be engaged with the output rod 18 by means of an output clutch 64 in another mode of operation, driving the output rod 18.

[0055] The first and second driving gears 60, 62 each comprise an annular body with gear teeth 66 arranged around a radially external surface and a central hole defined by a radially internal surface that is spaced from the output rod 18. The gear teeth 66 of the first and second driving gears 60, 62 mesh with the gear teeth 54 of the overlapping clutches 46a-d of the first and second input rods 14, 16.

[0056] A first drive gear 60 is positioned towards a first axial end 68 of the output rod 18 nearest to the first and second motors 4, 6, aligned and meshed with the first overlapping clutches 46 of both the first and second input rods 14, 16. A second drive gear 62 is positioned towards a second axial end 70 of the output rod 18 nearest to an output of the first gearbox 8, aligned and meshed with the second overlapping clutches 46a-d of both the first and second input rods 14, 16.

[0057] The arrangement of the overlapping clutches 46a-d allows either of the first and second input rods 14, 16 to actuate the rod. Petition 870230049480, dated 09 / 06 / 2023, page 17 / 49 / 26 of output 18 while preventing the jamming of the drive gears 60, 62. For example, engaging the first input rod 14 in the first direction transmits torque through the first overlapping clutch 46a to the first drive gear 60, causing the output rod 18 to rotate in the opposite second direction. The first drive gear 60 is also engaged with the first overlapping clutch 46b of the second input rod 16, but the first overlapping clutch 46b of the second input rod 16 can rotate freely when the first overlapping clutch 46a of the first input rod 14 is driving. In this way, the movement of the drive gear 60 is not captured despite the connection with both first overlapping clutches 46a, 46b.Therefore, the first motor 4 can drive the output rod 18 while the second motor 6 is stationary or running at a lower speed compared to the first motor 4.

[0058] A similar function occurs if, conversely, the second input rod 16 is driven by the second motor 6 to rotate faster than the first input rod 14. In this mode, the first overlapping clutch 46b on the second input rod 16 drives the first drive gear 60 and the first overlapping clutch 46a on the first input rod 14 rotates freely.

[0059] Output rod 16 can receive drive input from either of the first of the second motors 4, 6 via the first and second input rods 14, 16. This allows, for example, one of the first and second motors 4, 6 to be supplied as the primary motor and the other to be retained as a secondary or redundant motor in case of failure of the primary motor.

[0060] Furthermore, the arrangement of system 2 described above is such that the speed of the output of drive system 12 is the same when driven by either motor. This contrasts, for example, with a Petition 870230049480, dated 09 / 06 / 2023, page 18 / 49 / 26 differential gearbox arrangement with two motors, where the output speed of the gearbox is proportional to an average of the input speeds, so that driving only one motor causes the output to rotate at half the normal speed.

[0061] In another mode of operation, if the first and second input rods 14, 16 are driven at substantially the same speed, both will drive the first drive gear 60 and transfer torque to the output rod 18. The torque of the output rod 18 is a combination of the torques of the input rods 14, 16. Any accidental or intermittent differences in the speed of the first and second motors 4, 6 and the input rods 14, 16 that might otherwise cause jamming or locking of the drive gear 60 are instead compensated for by the presence of the overlapping clutches 46.

[0062] In addition to being actuatable in the second direction of rotation as described above, the output rod 18 is actuatable in the first direction of rotation by either of the first and second input rods 14, 16 via the second drive gear 62 in a manner similar to that described above. Rotating either of the first or second input rods 14, 16 in the second direction engages the respective second overlapping clutch 46c, 46d, transferring torque to the second drive gear 62 and rotating the output rod 18 in the first direction. Again, the first and second motors 4, 6 can be used as primary and secondary motors or can provide a combined torque output.

[0063] Although the illustrated arrangement and the present description refer to an example in which two motors are used to drive an output, the same features can be applied to an embodiment of a drive system in which the input of any number of motors can be combined to provide a single output. In such examples, additional motors and input rods around the output rod may comprise Petition 870230049480, dated 09 / 06 / 2023, page 19 / 49 / 26 overlapping clutches that mesh with the drive gears in a manner similar to that described in relation to the first and second motors and input rods. Such an arrangement would function similarly to that described above, with each motor capable of driving the output rod independently or together to provide a combined torque output.

[0064] To allow the output rod 18 to be driven in either direction by either of the motors, a clutch connection or output clutch 64 is provided between the first and second drive gears 60, 62 and the output rod 18. The output clutch 64 selectively engages one or the other of the drive gears with the output rod 18, allowing torque transfer from the first drive gear 60 to the output rod 18 in a first mode of operation and from the second drive gear 62 to the output rod 18 in a second mode of operation.

[0065] The output clutch 64 includes a driven clutch piece 72, which is fixed or integrally formed with the output rod 18, and a pair of drive clutch pieces 74, 76, which engage independently and selectively with the driven clutch piece 72 to transfer torque from the drive gears 60, 62 to the output rod 18. The drive clutch pieces 74, 76 are axially movable in and out of contact with the driven clutch piece 72, to engage or disengage depending on the operating mode. The output clutch 64 comprises a first drive clutch piece 74 associated with the first drive gear 60 and a second drive clutch piece 76 associated with the second drive gear 62.

[0066] In the arrangement shown, the clutch connection is a conical clutch. The driven clutch portion 72 is centrally located on the output rod 18 and comprises a body with a Petition 870230049480, dated 09 / 06 / 2023, page 20 / 49 / 26 surface 78 defining two male conical elements facing opposite axial directions. Each of the parts 74, 76 of the drive clutch comprises a body with a surface 80 defining female conical elements, facing the respective male conical elements and correspondingly shaped to receive the male conical elements. The parts of the drive clutch 74, 76 are configured to be moved axially along the output rod 18, to enter and exit contact with the driven clutch part 72 and to selectively engage with the driven clutch part 72 by means of friction between the surfaces 78, 80 of the clutch parts.

[0067] In an alternative conical clutch, which is not illustrated, the driven clutch part may comprise a body with a surface defining two female conical elements, and the driving clutch parts may each comprise a body with male conical elements defining the surface. The function of the driven part and the driving parts is similar to that described above.

[0068] The drive clutch parts 74, 76 are positioned around the output rod 18 and coaxially with it. The drive clutch parts 74, 76 are configured to rotate freely around the output rod 18 when not engaged with the driven clutch part 72. The bodies of the drive clutch parts 74, 76 are annular, each comprising a central bore defined by a radially inner surface that is spaced from the output rod 18.

[0069] Figure 7 shows a view of the output rod 18 and the driven clutch piece 72 separately. The conical clutch further comprises a plurality of friction elements 82, configured to increase the friction linkage between the drive clutch parts 74, 76 and the driven clutch part 72. The plurality of friction elements 82 comprises arc segments positioned around the circumference of the Petition 870230049480, dated 09 / 06 / 2023, page 21 / 49 / 26 surface 78 of the driven clutch part 72 in each of the male conical elements. A circumferential separation between the arc segments forms axial oil channels 84 for lubricant flow around the frictional bonding surfaces. There is also an axial separation between the frictional elements of each of the two male conical surfaces, to define a circumferential oil channel 86 between them for similar purposes. The plurality of frictional elements 82 each comprises a section of material that is bonded to the surface 78 of the driven clutch part 72 and interfaces with the surfaces 80 of the driven clutch parts 74, 76 when the conical clutch is engaged. The material in one example is a tough para-aramid, for example polyparaphenylene terephthalamide.

[0070] In an alternative, not illustrated, the plurality of friction elements 82 may instead be fixed to the surfaces 80 of the drive clutch parts 74, 76 and interface with the surface 78 of the driven clutch part 72 when the tapered clutch is engaged.

[0071] The selective engagement of one or both parts of the drive clutch 74, 76 with the central drive clutch part 72 can be controlled through the use of ramp elements for bearings in the drive gears and in the drive clutch parts 74, 76. Figure 8 shows the first drive gear 60 in isolation. The first drive gear 60 comprises a plurality of ramp elements 88 shaped and configured to receive and cooperate with bearings 90. In the illustrated example, the ramp elements are ball ramps and the bearings are ball bearings.

[0072] The ramp elements 88 comprise depressions formed in the annular body of the drive gear 60 to form inclined surfaces. The ramp elements define a gradient in the axial direction, so that they extend circumferentially from an axially deeper end 92 to an axially shallower end 94, and so that Petition 870230049480, dated 09 / 06 / 2023, page 22 / 49 / 26 that narrow in width around the circumferential direction between the two ends 92, 94.

[0073] The second drive gear 62 comprises ramp elements similar to those described. The ramp elements 88 of each of the drive gears 60, 62 are circumferentially spaced around the annular body of the drive gear 60, 62 on one axial side thereof. The ramp elements 88 of each of the drive gears 60, 62 are axially directed inwards along the output rod 18, towards the driven part 72 of the output clutch 64.

[0074] Figure 9 shows a view along line B of Figure 2, showing the ramp elements and bearings in more detail. In addition to the ramp elements 88 formed in the drive gears 60, 62, similar ramp elements 96 are formed on an axial side of each of the drive clutch parts 74, 76 of the output clutch 64. The ramp elements 96 of the drive clutch parts 74, 76 are axially directed outwards, towards the drive gears 60, 62. The ramp elements 96 of the drive clutch parts 74, 76 comprise all the same features as the ramp elements 88 of the drive gears 60, 62, but are mirrored to those of the drive gears 60, 62, so that the inclined surfaces extend in an opposite direction circumferentially.

[0075] The drive gears 60, 62 and the drive clutch parts 74, 76 comprise a corresponding number of ramp elements 88, 96, such that each ramp element 88 in each drive gear 60, 62 has a corresponding ramp element 96 in the drive clutch part 74, 76. A ball bearing 90 is received between each ramp element 88 of the drive gear 74, 76 and the respective corresponding ramp element 96 of the drive clutch part. Petition 870230049480, dated 09 / 06 / 2023, page 23 / 49 / 26 actuation clutch 74, 76.

[0076] The ball bearings 90 act to transform a portion of the rotational force applied to the drive gear 60, 62 into an axial movement of the drive clutch piece 74, 76, for engagement with the driven clutch piece 72. When one of the drive gears 60, 62 is driven by one of the overlapping clutches 46a-d of the input rods 14, 16, the drive gear 60, 62 initially rotates relative to the drive clutch piece 74, 76. The ramp elements 88 of the drive gear 60, 62 force the ball bearing 90 circumferentially along the inclined surfaces of the ramp elements 88 and thus force the ball bearings 90 in an axial direction towards the drive clutch piece 74, 76. The ball bearing 90 is rests against the inclined surface of the ramp element 96 on the drive clutch piece 74, 76.The drive clutch piece 74, 76 is moved axially to engage with the driven clutch piece 72. With the output clutch 64 engaged, the output rod 18 rotates with the drive gear 60, 62.

[0077] Since the input rod 14, 16 and the drive gear 60, 62 are no longer receiving drive input, the ball bearing 90 is free to return along the inclined surfaces of the ramp elements 88, 96 and the drive clutch part 74, 76 is free to move axially out of engagement with the driven clutch part 72.

[0078] In an alternative not shown, the ramp elements may cooperate with a rolling element other than a ball bearing, such as a cylindrical roller bearing.

[0079] The configuration of the output clutch 64 is such that the rotation of any of the drive gears 60, 62 automatically engages the corresponding drive clutch part 74, 76 with the part of Petition 870230049480, dated 09 / 06 / 2023, page 24 / 49 / 26 actuated clutch 72. That is, the actuating clutch parts 74, 76 engage selectively based on the received rotational input. This mechanical automation can reduce the complexity of the output clutch 64 compared to a manual or electronically automated clutch, saving space and weight in the system.

[0080] Figure 10 shows a cutaway view of the drive system 2 along line C of Figures 1 and 3, showing one of a pair of bearing cages 98 that can be positioned around the output rod 18 to help regulate the movement of the ball bearings 90 within the ramp elements 88, 96. The first and second bearing cages 98 are provided between each of the first and second drive gears 60, 62 and the adjacent drive clutch parts 74, 76. Each of the bearing cages 98 comprises a disc with an annular body and a central bore defined by a radially internal surface that is spaced from the output rod 18. A plurality of openings 100 is formed in the body of the bearing housing disc 98, extending entirely through the body in the axial direction.

[0081] Returning to Figure 9, the bearing cages 98 are positioned alongside the drive gears 60, 62 and the drive clutch parts 74, 76. The openings of the bearing cages 98 are shaped to receive the ball bearings 90 so that the ball bearings 90 are within the openings 100 and between the cooperating ramp elements 88, 96 of the adjacent drive gear 60, 62 and the drive clutch part 74, 76. The bearing cages 98 act to restrict the circumferential position and separation of the ball bearings 90, which in turn regulates the axial movement of all the ball bearings 90 around the circumference. The cages 98 can thus provide a more robust and consistent axial actuation of the drive clutch parts 74, 76. Petition 870230049480, dated 09 / 06 / 2023, page 25 / 49 / 26

[0082] Figure 11 shows a cutaway view of the drive system 2 along line D of Figures 1 and 3, showing a drag disc arrangement 102 that can function to improve the responsiveness of the drive clutch parts and rolling elements to torque input.

[0083] Figure 12 shows a partial detailed view of Figure 3, showing features of the arrangement of the drag plate 102. The arrangement of the drag plate 102 comprises a static drag plate 104 that is fixedly attached to a static portion of the first gearbox, so that the plate is held against rotation, and a pair of drag pins 106, each attached to a respective part of the drive clutch parts 74, 76. The drag pins 106 each comprise a spring 108 that keeps the pin axially away from the drive clutch part 74, 76 to which it is connected. Each of the drag pins 106 supports one of the axial sides of the drag plate 104 so as to generate a relatively low and generally constant level of drag torque from the friction between the drag plate 104 and the drag pins 106.Springs 108 keep drag pins 106 in contact with drag plate 104 both when the respective drive clutch piece 74, 76 is separated from the driven clutch piece 72, and when it is engaged.

[0084] The arrangement of the drag plate 102 generates a low constant level of torque drag that must be overcome by any drive clutch part 74, 76 when it is initially engaged in rotation. The torque drag limits the rotation of the drive clutch part 74, 76 slightly relative to the respective drive gear 60, 62, so that the initial rotation of the drive gear 60, 62 will force the roller bearings along their ramp elements between the drive gear 60, 62 and the clutch part of Petition 870230049480, dated 09 / 06 / 2023, page 26 / 49 / 26 drive 74, 76, instead of just transferring torque to a part of the freewheel drive clutch 74, 76. The low level of torque drag thus ensures that the initial rotation of the drive gear 60, 62 causes axial movement and proper engagement of the drive clutch part 74, 76.

[0085] Although low drag levels in the drive clutch components for roller bearing actuation can be provided by other design aspects, the use of a drag disc arrangement can allow fine adjustment of the drag level by means of the drag pins. By properly adjusting the low drag level, the proper functioning of the drive clutch components can be ensured without inducing unnecessary inefficiency.

[0086] Figure 13 shows a partial detailed view of Figure 3, showing the internal features of the second gearbox 10 in more detail. The second gearbox 10 is configured to provide additional speed reduction at the output of the first gearbox 8 to an output of the drive system 12 of the overall drive system 2.

[0087] The second gearbox 10 comprises an input rod 110 for receiving torque from the output rod 18 of the first gearbox 8. The output rod 18 and the second input rod of the gearbox 110 comprise a connection for rotating together. In the example shown, the connection comprises a pipe shaft 112 which is received into the respective openings formed at the axial ends of the output rod 18 and the input rod 110. The input rod 110 comprises gear teeth 114 arranged around an annular periphery.

[0088] The second gearbox 10 comprises an elliptical gear system 116 to provide sufficient speed reduction in a relatively small space. The gear system 116 Petition 870230049480, dated 09 / 06 / 2023, page 27 / 49 / 26, comprises a first set of planetary gears 118 that mesh with the teeth of gear 116 of input rod 110, so that input rod 110 acts as a sun gear. The gear system further comprises a ring gear 120 surrounding the first set of planetary gears 118 and fixed to an inner periphery of the second gearbox 10. Rotation of input rod 110 in a first direction drives rotation of the first set of planetary gears 118 in the same direction within the fixed ring gear 120.

[0089] The first planetary gear set 118 is held by a first gear carrier 122, which comprises pins 124, each pin 124 positioned on one of the first planetary gear sets 118 so that the carrier 120 rotates with the planetary gears 118. The carrier 122 comprises a carrier shaft section 126 that extends axially from the pins 124 to provide the rotational output of the first planetary gear set 118.

[0090] In the example shown, the gear system 116 is a two-stage elliptical gear system to provide additional speed reduction in a space-efficient arrangement. The gear system further comprises a second set of planetary gears 130 arranged around the carrier shaft 126 of the first gear carrier 122, axially adjacent to the first set of planetary gears 116. The carrier shaft 126 comprises gear teeth 128 around an outer periphery, which meshes with the teeth of the second set of planetary gears 130. The second set of planetary gears 130 rotates within the same fixed ring gear 120 as the first set of planetary gears 118. A second gear carrier 132 comprises pins 134, each pin 134 positioned in one of the second set of gears. Petition 870230049480, dated 09 / 06 / 2023, page 28 / 49 / 26 planetary gears 130 so that the second gear support 132 rotates with the second planetary gear set 130. The second carrier 132 also comprises a shaft section 136 that extends axially from the pins 134 to provide the rotational output.

[0091] The second gearbox 10 comprises a second gearbox output rod 138 which is driven by the output of the gear system. In the example shown, the output rod 138 comprises a splined connection to the rod section 136 of the second conveyor 132. The output rod 138 acts as the output of the drive system 12, providing the output drive of the drive system of the general actuator 2.

[0092] The first gearbox 8 provides some speed reduction, so that the output rod 18 of the first gearbox 8 rotates more slowly than the input rod or rods 14, 16, which rotate at the drive speed of the motors 4, 6. The second gearbox 10 provides a greater speed reduction than the first gearbox 8, to further reduce the overall speed reduction of the system between the motors 4, 6 and the drive system output 12. The second gearbox 10 may have a gear ratio more than five times that of the first gearbox 8.

[0093] As shown in Figure 14, the actuator drive system 2 can be part of an actuator assembly 140, with the drive system 2 arranged to drive an actuator 144, such as a linear actuator. The above-described features of the drive system 2, with two motors configured to provide dual or redundant output in two directions of rotation, can be particularly useful in the context of driving such an actuator, which may require robust operation in two directions of actuation.

[0094] The actuator 2 drive system may also be part Petition 870230049480, dated 09 / 06 / 2023, page 29 / 49 / 26 of a control surface assembly 142 for an aircraft. In the control surface assembly, drive system 2 is arranged to actuate actuator 144, and actuator 144 is arranged to move control surface 146. The above-described features of drive system 2 may be particularly useful in the context of driving an aircraft control surface, where redundant operation is important for safety reasons, space and weight considerations are especially important, and dual-motor operation may be used to provide additional torque in some situations, such as mechanical limit cases or emergency operation.

[0095] Although certain provisions are described above by way of example, it will be appreciated that various changes and modifications may occur without departing from the scope of this application. Petition 870230049480, dated 09 / 06 / 2023, pages 30 / 49

Claims

1 / 4 CLAIMS 1. Actuation system (2) for an actuator, wherein the actuation system (2) is characterized in that it comprises: first and second motors (4, 6); first and second input rods (14, 16) connected to be actuated by the respective first and second motors (4, 6), wherein each of the first and second input rods (14, 16) comprises: a first overlapping clutch (46a, 46b) configured to rotate with the input rod (14, 16) in a first direction; and a second overlapping clutch (46c, 46d) configured to rotate with the input rod (14, 16) in a second direction; a first driving gear (60) configured to be alternatively driven by one of the first overlapping clutches (46a, 46b), by the other of the first overlapping clutches (46a, 46b) or by both first overlapping gears together;a second drive gear (62) configured to be alternatively driven by one of the second overlapping clutches (46c, 46d), by the other of the second overlapping clutches (46a, 46b) or by both second overlapping gears together; an output rod (18); and an output clutch (64) associated with the output rod (18), wherein the output clutch (64) and the output rod (18) are arranged to be driven by the first drive gear (60) in a first operating mode of the drive system (2) and are driven by the second drive gear (62) in a second operating mode of the drive system (2);wherein the output rod (18) defines a geometric axis of rotation (Z), and the output clutch (64) comprises a driven clutch part (72) connected to the output rod (18) and the first and second drive clutch parts (74, 76) which are axially movable inward and outward engagement with the driven clutch part (72);wherein the first and second drive gears (60, 62) are each positioned adjacent to a respective of the first and second drive clutch parts (74, 76), each of the first and second drive gears (60, 62) and drive clutch parts (74, 76) comprising a plurality of ramp elements (88, 96), and a plurality of rolling elements (90) are positioned between the ramp elements (88, 96) of those adjacent to the first and second drive gears (60, 62) and drive clutch parts (74, 76).

2. Drive system (2) according to claim 1, characterized in that the plurality of rolling elements (90) comprises a plurality of ball bearings.

3. Drive system (2) according to claim 2, characterized in that it further comprises first and second bearing compartments (98), each bearing compartment (98) comprising a plurality of openings (100), the plurality of ball bearings being received within the plurality of openings (100).

4. Drive system (2) according to claim 1, characterized in that it further comprises a drag disc arrangement (102) comprising a drag plate (104) that is fixed against rotation and at least one drag pin (106) connected to one of the first and second drive clutch parts (74, 76) and in contact with the drag plate (104).

5. Drive system (2) according to claim 1, characterized in that the output clutch (64) comprises a conical clutch, the driven clutch part comprising a pair of male conical elements and each drive clutch part comprising a pair of female conical elements, one of the male conical elements in frictional contact with one of the pair of female conical elements in the first mode of operation and the other of the male conical elements in frictional contact with the other of the pair of female conical elements in the second mode of operation.

6. Drive system (2) according to claim 1, characterized in that the output clutch (64) comprises a conical clutch, each drive clutch part comprising a pair of male conical elements and each driven clutch part (72) comprising a pair of female conical elements.

7. Drive system (2) according to claim 1, characterized in that each of the first overlapping clutches (46a, 46b) and each of the second overlapping clutches (46c, 46d) comprise a one-way clutch, each having a plurality of one-way elements (56) in contact with the respective input rod (14, 16).

8. Drive system (2) according to claim 1, characterized in that it further comprises an epicyclic gearbox (10), wherein the output rod (18) is arranged to drive an input of the epicyclic gearbox (10).

9. Drive system (2) according to claim 1, characterized in that the first and second motors (4, 6) comprise the same maximum maximum speed capacity and / or the same speed-to-torque ratio.

10. Actuator assembly (140) for an aircraft control surface (146), wherein the actuator assembly (140) is characterized in that it comprises: Petition 870260035734, dated 04 / 16 / 2026, page 9 / 14 4 / 4 an actuator (144); and the drive system (2), as defined in any of the preceding claims, wherein the drive system (2) is connected to actuate the actuator (144). Petition 870260035734, dated 04 / 16 / 2026, page 10 / 14

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