Drive structure

Abstract

Drive Component A drive arrangement for operating a vehicle control surface includes a first drive device, a second drive device, an output member for connecting to the vehicle control surface, first engagement means for selectively engaging and disengaging the first drive device and the output member, and second engagement means for selectively engaging and disengaging the second drive device and the output member.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a drive arrangement for operating a vehicle control surface, and more particularly to a drive arrangement that provides redundancy in the event of a malfunction or failure. [Background technology]

[0002] Airplanes, helicopters, and other aircraft have a number of flight control surfaces, such as ailerons, elevators, wing flaps, rudders, and rotor blades, that are operated during flight (including takeoff and landing) to control the aircraft's movement. In many aircraft, the flight control surfaces are operated by electromechanical drive arrangements that apply forces to the flight control surface components to achieve the required configuration of the flight control surfaces and thus the desired aircraft movement.

[0003] In existing applications, such drive arrangements include a single drive (e.g., an electric motor) in combination with any necessary gearing and connection means to transmit power from the single drive to the flight control surfaces. In the event of a drive arrangement failure, the drive can be disconnected and / or disabled by a human pilot taking manual control.

[0004] The present invention aims to improve upon such drive arrangements. Summary of the Invention

[0005] According to one aspect of the present invention, there is provided a drive arrangement for operating a vehicle control surface, the drive arrangement comprising a first drive device, a second drive device, an output member for connecting to the vehicle control surface, first engagement means for selectively engaging and disengaging the first drive device and the output member, and second engagement means for selectively engaging and disengaging the second drive device and the output member.

[0006] Optionally, the drive arrangement includes at least one actuator configured to cause the first engagement means to engage and disengage the first drive device and the output member. The at least one actuator may be configured to cause the first engagement means to substantially simultaneously disengage the first drive device and cause the second engagement means to engage the second drive device and the output member. In some examples, the at least one actuator is configured to cause movement of a rod and a pair of arms attached to the rod. Optionally, the actuator, rod, and arms are configured to rotate about the first and second drive devices.

[0007] Optionally, the first engagement means comprises a clutch-based mechanism, such as a Hirth coupling or a friction clutch.

[0008] In some examples, the first engagement means comprises a first side configured to slide along a splined section of a first output shaft of the first drive device under action of the actuator to facilitate engagement and disengagement of the first drive device with the output member.

[0009] Optionally, the first engagement means comprises a planetary gear transmission. In some examples, the drive arrangement comprises a friction material configured to constrain movement of a ring gear of the planetary gear transmission. Optionally, the drive arrangement comprises a rocker configured to apply friction material to the ring gear. The friction material may be configured to move radially relative to the planetary gear transmission.

[0010] Optionally, the drive arrangement comprises at least one additional gearing.

[0011] In some examples, the first engagement means comprises a strain wave transmission. The strain wave transmission may comprise a variable size wave generator mechanism.

[0012] Optionally, the first drive unit is rotatably mounted within the housing on a bearing. The drive arrangement can include a torque arm rotatably mounted adjacent to the first drive unit and a force sensor configured to measure a force experienced by the torque arm. The force sensor may be mechanically grounded to constrain movement of the force sensor and the torque arm. The drive arrangement may include a pin configured to be operated by an actuator to constrain the first drive unit and the torque arm so that they rotate together. Optionally, the second drive unit is rotatably mounted within the housing on a bearing. The drive arrangement may include a second actuator.

[0013] Optionally, the output member includes a connection portion configured to connect to a vehicle control surface.

[0014] In some examples, the first drive unit and the second drive unit are both arranged to be simultaneously engaged with the output member, and the first drive unit and the second drive unit are independently disengageable from the output member to allow the other drive unit to independently control the output member.

[0015] According to another aspect of the present invention, there is provided a vehicle comprising a drive arrangement as described above.

[0016] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a drive arrangement having two drives that can be selectively engaged with an output member via respective Hirth couplings. [Figure 2] FIG. 2 shows a portion of the drive arrangement of FIG. 1. [Figure 3] FIG. 1 illustrates a drive arrangement having two drives that can be selectively engaged with an output member through respective friction clutches. [Figure 4]FIG. 1 illustrates a drive arrangement having two drives that can be selectively engaged with an output member through respective planetary gear transmissions. [Figure 5] FIG. 5 shows an output member of the drive arrangement of FIG. 4; [Figure 6] FIG. 1 illustrates a drive arrangement having two drive devices that can be selectively engaged with an output member through respective strain wave transmissions. [Figure 7] FIG. 10 illustrates a wave generator of a strain wave gear transmission in an elongated, elongated configuration for engaging the inner flexspline and outer circular spline of the strain wave gear transmission. [Figure 8] FIG. 10 illustrates a wave generator of a strain wave gear transmission in a retracted, shortened configuration for separating the inner flexspline and outer circular spline of the strain wave gear transmission. [Figure 9] FIG. 10 illustrates a drive arrangement having two drives that can be selectively engaged with an output member by respective torque arms and retractable couplings. [Figure 10] FIG. 10 shows a portion of the drive arrangement of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0018] The following examples illustrate a variety of different drive arrangements for operating vehicle control surfaces. Each of the drive arrangements includes two drives that can be selectively engaged with an output member for forward connection to the vehicle control surface, providing redundancy in the event of a drive malfunction or failure. The examples include different mechanisms for selective engagement of the drives with the output member. As described in more detail below, the different examples can be combined in multiple ways, including using a mechanism from one example with a mechanism from another example in combinations not shown, and combining different drive arrangements (i.e., two or more additional drives) to achieve greater redundancy.

[0019] FIG. 1 shows a first example of a drive arrangement 101 comprising a first drive device 103 having an output shaft 105 connected to a first side 107 of a first Hirth coupling 108. In FIG. 1, the first side 107 of the first Hirth coupling 108 is meshed with a second side of the first Hirth coupling 108. The second side of the first Hirth coupling 108 is mounted on, or formed as part of, an output member 109 that is rotatably mounted on a bearing 129. Thus, rotation of the output shaft 105 by the first drive device 103 causes rotation of the output member 109 as the rotation is transferred between the meshed sides of the first Hirth coupling 108. The output member 109 has a connecting portion 111 at its upper end for connecting the output member 109 to another component (e.g., a connector 131, as shown in FIG. 2) to enable motion of the output member 109 to be transferred to a vehicle control surface.

[0020] The drive arrangement 101 also includes a second drive 113 (which in the illustrated example is the same as the first drive 103). The second drive 113 includes an output shaft 115 that is connected to a first side 117 of a second Hirth coupling 118.

[0021] In FIG. 1 , the first side 117 of the second Hirth coupling 118 is not engaged with the second side 119 of the second Hirth coupling 118. However, the actuator 121 is configured to separate the first and second sides of the first Hirth coupling 108 by retracting a rod 123 that connects the actuator 121 to a first arm 125 that is connected to the first side 107 of the first Hirth coupling 108. Retracting the rod 123 also moves a second arm 127 that is connected to the rod 123 and the first side 117 of the second Hirth coupling 118, thereby engaging the first side 117 of the second Hirth coupling 118 with the second side 119 of the second Hirth coupling 118. This allows the second drive device 113 to take over responsibility for driving the output member 109. The actuator 121 may cause this transfer of responsibility if the first drive unit 103 malfunctions (e.g., ceases or stops providing the intended rotational output in terms of torque or speed), allowing normal operation to continue under the influence of the second drive unit 113. This may further allow for selective use of different drives 103, 113 (which may have different respective parameters, e.g., different torque profiles) at different times to optimize the function of the corresponding vehicle control surfaces.

[0022] In the illustrated example, the output shafts 105, 115 include respective splined sections 106, 116 that engage corresponding splined openings in the first side 107 of the first Hirth coupling 108 and the first side 117 of the second Hirth coupling 118 to allow for the transmission of rotational motion from the output shafts 105, 115 to the first side 107, 117 and also the necessary axial movement of the first side 107, 117 along the output shafts 105, 115 for engagement and disengagement of the first and second Hirth couplings 108, 118. In other examples, alternative couplings such as flexure links may be provided in place of the splined sections 106, 116 that allow free translation along the link shafts but provide a rigid torque coupling. The double arrows in FIG. 1 indicate the direction of movement of the rod 123 and the first sides 107, 117 of the Hirth couplings 108, 118 to achieve engagement and disengagement with their respective second sides (which are axially stationary, i.e., do not move axially).

[0023] Multiple instances of the drive arrangement 101 shown in FIG. 1 may be connected to a common shaft (e.g., via respective connecting portions 111 of their output members 109) to allow for additional redundancy (i.e., where the single drive arrangement shown in FIG. 1 provides one redundant drive unit, two drive arrangements 101 coupled to a common shaft as described would provide three redundant drive units).

[0024] 2 shows an axial view of second arm 127, output member 109, and connector 131 connected to output member 109 at connection portion 111. The dashed straight lines demarcate the range of possible orientations of the central axis of output member 109 under the action of first and second drive devices 103, 113. The dashed curved lines indicate the path swept by the end of connector 131 connected to output member 109 at connection portion 111. This movement of connector 131 may be used to operate a vehicle control surface, either directly or through one or more additional connections or linkages to translate the movement of connector 131 into the type of movement required for the corresponding vehicle control surface.

[0025] FIG. 3 shows a further example of a drive component 301. In this example, instead of the Hirth couplings 108, 118, there are friction clutches 308, 318 having respective first and second clutch plates 307, 317, 319. The operation of the drive component 301 is substantially similar to that of the drive component 101. A first drive device 303 rotates an output shaft 305, causing rotation of a first side 307 of a first friction clutch 308 (via a splined section 306). In the configuration shown in FIG. 3, the first side 307 of the first friction clutch 308 is engaged with a second side 307 of the first friction clutch 308, which is attached to or formed as part of an output member 309. Thus, rotation from the first drive device 303 can be transferred to the output member 309, which is rotatably mounted within a bearing 329.

[0026] If first drive unit 303 fails, actuator 321 can retract rod 323, moving arms 325 and 327 to the left in FIG. 3 . This disengages first friction clutch 308 by separating first side 307 from the second side of first friction clutch 308. Simultaneously, second friction clutch 318 is engaged because first side 317 of second friction clutch 318 engages second side 319 of second friction clutch 318 due to the leftward movement of rod 323 and arm 327. Thereafter, when second drive unit 313 rotates output shaft 315, rotation of engaged first and second sides 317, 319 of second friction clutch 318 is caused (via splined section 316) to occur, causing rotation of output member 309.

[0027] As in the example of FIG. 1, output member 309 includes a connection portion 311 by which output member 309 may be connected to a further component, such as connector 131 shown in FIG.

[0028] Similar to the drive arrangement 101 of FIG. 1, multiple instances of the drive arrangement 301 shown in FIG. 3 may be connected to a common shaft (e.g., via respective connecting portions 311 of their output members 309) to allow for additional redundancy (i.e., where the single drive arrangement shown in FIG. 3 provides one redundant drive, two drive arrangements 301 coupled to a common shaft as described would provide three redundant drives).

[0029] 1 and 3 are clutch-based examples, involving axial movement (along the drive output shaft) of first sides 107, 117, 307, 317 to engage and disengage respective drives 103, 113, 303, 313 and output members 109, 309. Hirth couplings 108, 118 and friction clutches 308, 318 are disengaged / engaged (respectively) substantially simultaneously under the action of corresponding actuators 121, 321, rods 321, 323 and arms 125, 127, 325, 327. Rods 321, 323 and arms 125, 127, 325, 327 also move axially (parallel to the drive output shaft).

[0030] 1 and 3, the actuators 121, 321, rods 123, 323, and arms 125, 127, 325, 327, together with the output members 109, 309, also rotate about axes shown by dashed lines in the figures.

[0031] FIG. 4 shows another example of a drive arrangement 401 including a first drive 403 having an output shaft 405 connected to or forming at least a portion of a "sun" gear of a first planetary or planetary gear transmission 433 (the illustrated splined section 406 can function as the sun gear). A "ring" gear 434 of the first planetary gear transmission 433 is a trunnion mounted in a bearing 435 that allows the ring gear 434 to rotate about the shaft 405. A first friction material 437 is provided adjacent to the ring gear 434. Under the action of the actuator 421, a rod 439 acts as a rocker, forcing a first arm 441 upward and bringing the first friction material 437 into contact with the ring gear 434 to prevent the ring gear 434 from rotating in the bearing 435. This allows drive power to be transmitted downstream from first drive unit 403 through first planetary gear transmission 433 toward output member 409. Drive power may be transmitted from first planetary gear transmission 433 to one or more intervening components, such as the illustrated additional planetary gear transmissions 443 and 445. The multiple planetary gear transmissions 433, 443, 445 may cooperate to provide various output speeds and torques to output member 409 using the output from first drive unit 403. First friction material 437 may be provided as a block (e.g., similar to a brake block), as a band extending around a substantial portion of the circumference of ring gear 434 (e.g., similar to a brake band), or in another form. Actuating actuator 421 pivots rocker 439, which, depending on the direction of actuation, moves first arm 441 closer or farther from ring gear 434, thus bringing first friction material 437 into or out of contact with ring gear 434. This allows selective engagement or disengagement of first drive device 403 from output member 409 by retaining or releasing the ring gear as appropriate.

[0032] The drive arrangement 401 includes a similar set of components on the opposite side of the output member 409. A second drive 453 is provided, with an output shaft 455 connected to or forming at least a portion of a sun gear of a second planetary gear transmission 457 (the illustrated splined section 456 can function as the sun gear). The ring gear 454 of the second planetary gear transmission 457 is also trunnion mounted on respective bearings 452 that allow the ring gear 454 to rotate about the shaft 455. A second friction material 458 is provided adjacent to the ring gear 454. Operation of the actuator 421, rocker 439, and second arm 459 allows or prevents rotation of the ring gear 454, and thus moves the second friction material 458 out of or into contact with the ring gear 454 to control whether drive force is transmitted from the second drive 453 to the output member 409. Similar to the example shown in Figures 1 and 3, the rocking movement of rod 439 under the action of actuator 421 allows for the engagement of one drive 403, 453 and the disengagement of the other drive 453, 403 substantially simultaneously.

[0033] In the exemplary drive arrangement 401 shown in FIG. 4, the actuator 421, rocker 439, and arm 441 do not rotate about the dashed axis of the drive arrangement 401.

[0034] Similar to the drive arrangements 101, 301 of Figures 1 and 3, multiple instances of the drive arrangement 401 shown in Figure 4 may be connected to a common shaft (e.g., via respective connecting portions 411 of their output members 409) to allow for additional redundancy (i.e., where the single drive arrangement shown in Figure 4 provides one redundant drive, two drive arrangements 401 coupled to a common shaft as described would provide three redundant drive units).

[0035] In the example shown, friction materials 437, 456, arms 441, 459, and other engagement / disengagement components are provided around first and second planetary gear transmissions 433, 457 (which are first planetary gear transmissions downstream of the first and second drive units 403, 453, respectively) to engage and disengage the drive units 403, 453 and output member 409. This may advantageously mean that wear occurring during engagement / disengagement is minimized as the torque output at the first and second planetary gear transmissions 433, 457 may be expected to be lower than the torque output at the downstream planetary gear transmissions 443, 445 etc; therefore, the torque change during engagement / disengagement is lower, leading to less stress and wear on the components. However, engagement / disengagement components may alternatively be provided about downstream planetary gear transmissions 443, 445, etc., with the same ability to engage / disengage drives 403, 453 and output member 409. For example, arm 441, friction material 437, and bearing 435 may be provided about planetary gear transmission 443 to allow the drive force through planetary gear transmission 443 to be engaged and disengaged. A corresponding planetary gear transmission on the other side of output member 409 (a second planetary gear transmission downstream of drive 453) may then have arm 459, friction material 456, and bearing 452 provided thereabout to achieve disengagement / engagement between the second drive 453 and output member 409. However, in some cases it may be preferable to have different planetary gear transmissions engaged / disengaged on either side of the output member 409 (e.g., a first planetary gear transmission downstream of one drive and a third planetary gear transmission downstream of the other drive), which may be achieved by appropriate configuration of the actuator 421, rod 439, and other components, or in other ways, for example, by replacing those components with independent actuators for the two planetary gear transmissions on either side of the output member 409.Such a configuration may be particularly advantageous in arrangements where the sets of planetary gear transmissions on either side of the output member 409 are arranged to provide different and complementary torque ratios, such that swapping from one drive to the other allows access to different ranges of torque output.

[0036] Figure 5 shows an axial side view of the example output member 409 shown in Figure 4. Similar to the output member 109 shown in Figure 2, the output member 409 can move through a variety of orientations (again, demarcated by dashed lines in the figure). As in Figure 2, a connector can be attached to the output member 409 at a connecting portion 411. Also, as in Figure 2, corresponding movement of the connector can be used to operate a vehicle control surface.

[0037] 6 shows another example of a drive arrangement 601 comprising a first drive 603 having an output shaft 605 connected to an input (not shown) of a first strain wave gear transmission 606. An output component 608 of the first strain wave gear transmission 606 is connected to an output member 609, such as output members 109 and 409 of FIGS. 1 and 4. The drive arrangement 601 also includes a second drive 613 having an output shaft 615 connected to an input (not shown) of a second strain wave gear transmission 616. An output component 610 of the second strain wave gear transmission 616 is connected to the output member 609.

[0038] As shown in FIG. 6 , the first strain wave gear transmission 606 includes a first mechanism 631 that functions as the wave generator component of the first strain wave gear transmission 616 and is movable between the configurations shown in FIGS. 7 and 8 . In the configuration shown in FIG. 7 , the wave generator is elliptical or oval in shape with an elongated or elongated major axis and deforms the flex spline component 701 of the strain wave gear transmission 606, causing the teeth of the flex spline component 701 to contact the teeth of the outer circular spline component 703 of the strain wave gear transmission 606 at the apex of the major axis of the ellipse. In the configuration shown in FIG. 8 , the major axis of the wave generator is shorter, meaning that the shape of the wave generator is closer to a circle, and the teeth of the flex spline component 701 do not engage with the teeth of the outer circular spline component 703. By moving the wave generator component between these configurations, the first drive device 603 can be engaged with and disengaged from the output member 609. With reference to Figures 6, 7, and 8, the wave generator of the first wave gear transmission 606 is provided by the hinge mechanism 631, the outer circular spline component 703 of the first wave gear transmission 606 is provided by the ring 635, and the flex spline component 701 of the first wave gear transmission 606 is provided by the output component 608.

[0039] The drive arrangement 601 includes a similar set of components on the opposite side of the output member 609. A second drive 613 is provided with an output shaft 615. Also provided is a second strain wave gear transmission 616 that includes a second mechanism 633 that acts as the wave generator component of the second strain wave gear transmission 616. An output component 610 of the second strain wave gear transmission 616 is connected to the output member 609.

[0040] As shown at the bottom of FIG. 6 , an actuator 621 is provided that causes movement of first and second mechanisms 631, 633 via rod 623 and connecting arms 625, 627, which act to move mechanisms 631, 633 between the extended and retracted configurations shown in FIGS. 7 and 8 . As with the previous example, engagement and disengagement of first and second strain wave transmissions 606, 616 by actuator 621, rod 623, and arms 625, 627 occurs substantially simultaneously. Specifically, when actuator 621 moves rod 623 to the left (toward the configuration shown in FIG. 6 ), arm 625 pulls the illustrated hinge of mechanism 631 toward the illustrated more angled configuration, reducing the outer diameter of the wave generator defined by mechanism 631, thereby decoupling first drive unit 603 from output member 609. At the same time, movement of rod 623 and arm 627 to the left pushes the illustrated hinge of mechanism 633 toward the flatter configuration shown, increasing the outer diameter of the wave generator defined by mechanism 633, thereby engaging second drive unit 613 with output member 609. Meanwhile, the opposite occurs when actuator 621 moves rod 623 to the right, resulting in first drive unit 603 engaging output member 609 and second drive unit 605 disengaging from output member 609.

[0041] Inputs (not shown) of the strain wave gear transmissions 606, 616 connect the output shafts 605, 615 of the first and second drive units 603, 613 to the first and second mechanisms 631, 633 to transmit rotation from the output shafts 605, 615 to the first and second mechanisms 631, 633. The inputs may be, for example, splined shafts as shown in the previous example, each having a non-splined section of the shaft extending through the arms 625, 627, respectively, to allow the arms 625, 627 to slide axially along the shaft, the splined portions of the shafts being positioned to engage corresponding splined openings in the left block of the hinge mechanism 631 and the right block of the hinge mechanism 633, at least when the respective hinge mechanisms 631, 633 are in the configuration shown in FIG. 7 and described in more detail below. Thus, the inputs of the strain wave gear transmissions 606, 616 function to transfer rotation to the hinge mechanisms 631, 633. Other forms of inputs are possible, such as flexure links or another component or set of components for transferring rotation from the output shafts 605, 615 to the hinge mechanisms 631, 633.

[0042] As with the previous drive arrangements 101, 301, and 401, multiple instances of drive arrangement 601 shown in FIG. 6 may be connected to a common shaft (e.g., via respective connecting portions 611 of their output members 609) to allow for additional redundancy (i.e., where the single drive arrangement shown in FIG. 6 provides one redundant drive, two drive arrangements 601 coupled to a common shaft as described would provide three redundant drives).

[0043] Wave gear transmissions, such as transmissions 606, 616 shown in FIG. 6, have a wave generator component configured to engage and disengage the flexspline component and the outer circular component of the wave generator component due to adjustment of at least one dimension of the wave generator component, and may be used in other drive configurations in place of clutches. For example, they may be used in environments such as automatic transmissions or other variable speed drivetrains that rely on a secondary clutching system. Advantageously, the illustrated wave gear transmissions may be relatively light, compact, and / or operate at high speeds compared to other types of clutching systems.

[0044] FIG. 9 shows another example of a drive arrangement 901 including a first drive unit 903 having an output shaft 905 connected to an output member 909. The first drive unit 903 is trunnion mounted on a bearing 907 such that the first drive unit 903 can rotate on a bearing within a first housing 908. A first torque arm 921 is also trunnion mounted about the same axis of rotation as the first drive unit 903. The first torque arm 921 is releasably connected to the first drive unit 903 such that the first drive unit 903 and the first torque arm 921 rotate together when connected and can rotate relative to each other when the releasable connection is removed. In the example shown, the releasable connection is provided by a first pin 925 controlled by a first actuator 927. When the first pin 925 is in the position shown, the first drive unit 903 and the first torque arm 921 rotate together. When the first actuator 927 retracts the first pin 925 from the first drive 903, the first drive 903 and the first torque arm 921 are free to rotate independently. The first sensor 923 monitors the force or torque experienced by the first torque arm 921. If the first sensor 923 measures an abnormal force / torque, indicating that the first drive 903 is malfunctioning, the first sensor 923 commands or may command the first actuator 927 to retract the first pin 925. Retracting the first pin 925 means that the first drive 903 is no longer constrained by the first torque arm 921 and therefore may rotate freely within its trunnion bearing 907 and no longer provides output to the output shaft 905 (and therefore the output member 909) because it no longer has resistance to work against.

[0045] The drive arrangement 901 includes a similar set of components on the opposite side of the output member 909. The drive arrangement 901 includes a second drive 913 having an output shaft 915 connected to the output member 909. Like the first drive 903, the second drive 913 is trunnion mounted on a bearing 917 such that the second drive 913 can rotate on the bearing 917 within a second housing 918. A second torque arm 931 is also trunnion mounted about the same axis of rotation as the second drive 913. The second torque arm 931 is releasably connected to the second drive 913 such that the second drive 913 and the second torque arm 931 can rotate together when connected and relative to each other when the releasable connection is removed. In the illustrated example, the releasable connection is provided by a second pin 935 controlled by a second actuator 937. When the second pin 935 is in the position shown, the second drive 913 and the second torque arm 931 rotate together. When the second actuator 937 retracts the second pin 935 from the second drive 913, the second drive 913 and the second torque arm 931 are free to rotate independently. The second sensor 933 monitors the force or torque experienced by the second torque arm 931. If the second sensor 933 measures an abnormal force / torque, indicating that the second drive 913 is malfunctioning, the second sensor 933 commands or can command the second actuator 937 to retract the second pin 935. Retracting the second pin 935 means that the second drive 913 is free to rotate within its trunnion bearing 917 and no longer has any resistance to act on, so it no longer provides any output to the output shaft 905 (and therefore the output member 909).

[0046] Thus, the drive arrangement 901 allows either the first drive unit 903 or the second drive unit 913 to selectively provide an output to the output member 909 by selectively disconnecting the first drive unit 903 or the second drive unit 913 from its corresponding torque arm 921, 931, meaning that the output of the disconnected drive unit 903, 913 is not directed to the output member 909; instead, the disconnected drive unit 903, 913 rotates freely within its trunnion bearings 907, 917. The other drive unit can then provide an output to the output member 909 as required.

[0047] As with the previous drive arrangements 101, 301, 401, 601, multiple instances of the drive arrangement 901 shown in FIG. 9 may be connected to a common shaft (e.g., via respective connecting portions 911 of their output members 909) to allow for additional redundancy (i.e., where the single drive arrangement shown in FIG. 9 provides one redundant drive, two drive arrangements 901 coupled to a common shaft as described would provide three redundant drive units).

[0048] Figure 10 shows the drive arrangement 901 of Figure 9 in an axial (front) view from the left side of Figure 9, showing the first actuator 927, the first sensor 923, the first torque arm 921, the first drive 903, the first housing 908, and the output member 909. As can be seen in Figure 10, the first sensor 923 is mechanically grounded to provide a resistance against which the first drive 903 can push when the first drive 903 is connected to the first torque arm 921 via the first pin 925.

[0049] 9 and 10, the pins 925, 935 have been described as being actuatable by actuators 927, 937; however, in other instances, shear pins, break knuckles, or other disposable components designed to fail under unexpected force / torque conditions may be provided. This may advantageously reduce the size and cost of the drive arrangement 901 by eliminating the need for actuators, while still providing the desired result of isolating a malfunctioning drive unit 903, 913 from its respective torque arm 921, 931 to isolate the malfunctioning drive unit 903, 913 from the output member 909. The remaining drive units 913, 903, still engaged by virtue of their own pins 935, 925 remaining intact, can then provide the necessary driving force to the output member 909 and any vehicle control surfaces attached thereto.

[0050] Each of the drives 103, 113, 303, 313, 403, 453, 603, 613, 903, and 913 may be a motor alone or a motor and gearing combination, depending on the particular scenario and desired output. For example, the drives 103 and 113 shown in FIG. 1 are preferably motor-gearing pair combinations (each combination is represented as a single "drive") because no other gearing (e.g., transmissions) is shown between the drives 103 and 113 and the output member 109. Therefore, it may be necessary to include gearing within the drives 103 and 113 to achieve the desired output rotational speed, torque, and / or other parameters at the output member 109. In contrast, the drives 403 and 453 shown in FIG. 4 may be motors alone because transmissions 433, 443, 445, etc. are provided between the drives 403 and 453 and the output member 409. These transmissions 433 , 443 , 445 may be configured to achieve desired output parameters of the output member 409 .

[0051] Any of the drive arrangements described, illustrated, and claimed may include one or more torque monitoring sensors configured to measure the torque provided by the drive units to monitor for spikes, sudden drops, or other torque anomalies that indicate a malfunction or failure of the drive units. Data collected by the sensors may be used to determine when to activate an actuator (such as the illustrated actuators 121, 321, 421, 621, 927, and 937) to cause the disengagement of a drive unit that the sensor indicates is malfunctioning and the engagement of another drive unit instead. Data collected by the sensors may also be used to determine how much torque a drive unit about to take over from another drive unit needs to apply to smooth the transition between drives.

[0052] A torque monitoring sensor (or additional sensors) may monitor how much a given drive and / or the output member to which it is connected has rotated. This may allow another drive within the drive arrangement to ensure that it is pre-aligned with the output member when attempting to engage it to take over responsibility for driving the output member. This may be particularly important for the Hirth couplings 108, 118 shown in FIG. 1, where precise alignment of the teeth or tips on the Hirth coupling's sides 107, 117, 119 may be important to prevent damage or blockage when the sides attempt to engage.

[0053] Any of the drive arrangements described, illustrated, and claimed may include one or more controllers configured to control the overall operation of the drive arrangement or its subcomponents. For example, the controller may control the drives 103, 113, etc. to ensure that the drives provide the required output. The controller may also receive and use data from the sensors described above to determine when to activate the actuators described above. The controller may further receive data from other sources, such as a computer, joystick, pedals, handheld wireless controller, or other input device providing instructions regarding the intended motion of the vehicle in which the drive arrangement is installed. The controller may include one or more processors, which may be implemented using a general-purpose or dedicated processing engine, such as a microprocessor, microcontroller, or other control module. The controller may be accompanied by one or more computer-readable storage media on which instructions for controlling the drive arrangement may be provided. The controller may also be accompanied by a communications interface. Such a communications interface may be used to allow software and data to be transferred between the controller and external devices, such as a computer, joystick, pedals, handheld wireless controller, or other input device described above.

[0054] The output members 109, 309, 409, 609 and 909 may be crank arms or levers that may be connected to a crankshaft or other component to convert the angular rotation of the connecting portion 111, 311, 411, 611 and 911 of the output member into a different type of motion or to transmit the angular rotation to a required component.

[0055] The term "engage" (and, mutatis mutandis, "disengage") as used herein with respect to the relationship between a driver and an output member includes the possibility of establishing a full physical and mechanical connection between the driver and the output member where a full connection did not previously exist (e.g., as in drive assemblies 101 and 301 of FIGS. 1 and 3, where Hirth couplings 108, 118 and friction clutches 308, 318 make and break the mechanical connection between drivers 103, 113, 303, 313 and output member 109, 309), as well as other modifications that allow for the transfer of force from the driver to the output member where force could not previously be transferred from the driver to the output member. For example, in drive assembly 901 shown in FIG. 9, output shaft 905 of first driver 903 and output shaft 915 of second driver 913 are always connected to output member 909, so that a full physical and mechanical connection always exists between first and second drivers 903, 913 and output member 909. However, due to the trunnion mounting of the drives 903, 913 on the bearings 907, 917, if the respective pins 925, 935 are not in the positions shown in Figure 9, it is not possible to transmit force from either of the drives 903, 913 to the output member 909, and the mechanical grounding of the sensors 923, 933 to which the torque arms 921, 931 are connected constrains the rotation of the drives 903, 913 in the bearings 907, 917.

[0056] As used herein, the term "mechanically grounded" indicates that the referenced component is attached to a locally static component, such as the housing of an aircraft or other vehicle in which the drive arrangement is implemented, thereby preventing movement of the referenced component relative to that locally static component. Mechanical grounding is shown in diagrams where it helps the reader understand the movement and interaction of different components (see, for example, the "antenna"-like symbols on drives 103, 113 in FIG. 1). As an example, in FIGS. 1 and 3, drives 103, 113, 303, 313 are mechanically grounded, meaning that they do not rotate relative to the vehicle body or other component to which they are attached. Similarly, bearings 129, 329 to which output members 109, 309 are attached are also mechanically grounded. However, the actuators 121, 321 and connected rods 123, 323 and arms 125, 127, 325, 327 are not mechanically grounded, which means that they can rotate about the illustrated (dashed) axis when the drive 103, 113, 303, 313 causes rotation of the first side 107, 117, 307, 317 to which the actuators 121, 321 are attached via the arms 125, 127, 325, 327 and rods 123, 323.

[0057] Although the drive arrangement 901 in FIG. 9 is shown with two sensors 923, 933 (one for each drive-torque arm combination) for maximum flexibility, in some versions of that drive arrangement, only a single sensor 923 may be provided. For example, in some versions, the first drive unit 903 may be considered a “primary” drive unit that is expected to be responsible for driving the output member 909 during normal operation. The second drive unit 913 may be considered a “secondary” drive unit that is expected to take over temporarily if the primary drive unit fails. In such versions, the secondary drive unit 913 may not have a sensor because the primary drive unit 903 may be expected to resume responsibility for driving the output member 909 as soon as possible (e.g., after the drive unit 903 is reset or repaired or replaced, if necessary); therefore, the secondary drive unit may not be expected to require monitoring because it should only be responsible for driving the output member 909 for a short period of time. Having only a single sensor may advantageously reduce the cost and weight of the drive arrangement 901 and the space consumed by the drive arrangement.

[0058] While the illustrated examples use the same two engagement means on either side of each output member 109, 309, 409, 609, 909 (i.e., two Hirth couplings 107, 117 are used in FIG. 1, two friction clutches 307, 317 are used in FIG. 3, etc.), different engagement means can be mixed if desired. For example, the Hirth coupling shown in FIG. 1 could be used with the friction clutch shown in FIG. 3 or the strain wave gear transmission shown in FIG. 6. Some non-matched pairings (such as the Hirth coupling and friction clutch or strain wave gear transmission described above) can still be simultaneously engaged and disengaged (and vice versa) by a single actuator. Alternatively, separate actuators may be provided depending on the desired drive arrangement performance characteristics.

[0059] While some drive arrangements provide only a single actuator, in some embodiments, a separate actuator may be provided for each drive in the drive arrangement (e.g., as shown in FIG. 9 ). This allows for greater flexibility in the timing of when a given drive is engaged or disengaged. For example, it may be desirable for both drives in a drive arrangement to be connected during normal operation, with one drive actively driving and the other drive remaining idle and following the first drive (i.e., being back-driven by the first drive), and not providing any significant assistance or resistance so that if the driving drive fails, the driving drive can be disengaged by its corresponding actuator and the previously idle / back-driven drive can be switched into drive mode. This can also be extended to cases where there are two or more redundant drives.

[0060] The drive arrangements described, illustrated, and claimed are suitable for operating control surfaces in any type of vehicle that includes a control surface. For example, the drive arrangements may be used with aircraft, such as airplanes, helicopters, autogyros, drones (unmanned aerial vehicles), and gliders, as well as with other types of vehicles, such as boats and submarines (e.g., to control rudders or other surfaces that affect the vessel's motion). The drive arrangements may be particularly advantageous for use with drones and other unmanned vehicles, because the redundancy provided by the drive arrangements allows for continued operation of the unmanned vehicle even if one of the drives fails; for example, another drive can take over in place of a human. However, the drive arrangements are equally suitable for use with manned vehicles and may provide an automated backup or failover control solution if the vehicle's pilot / driver is unable or chooses not to continue controlling the vehicle. Accordingly, manned vehicles may include additional components that enable the pilot / driver to control the vehicle. This may be a separate arrangement of components that allows the pilot / driver to control the vehicle control surfaces independently of the drive arrangement as described, shown, and claimed, or an arrangement in which the pilot / driver can control one or both of the drives of the drive arrangement to control the vehicle control surfaces via the drive arrangement. The vehicle may include means for detecting when the pilot / driver is no longer in control of the vehicle and automatically handing over control to the drive arrangement as described, shown, and claimed. Additionally or alternatively, the vehicle may include means for allowing the driver to hand over control to the drive arrangement. The inventions described in the original claims of this application are set forth below. [1] A drive arrangement for operating a vehicle control surface, comprising: a first drive unit; a second drive unit; an output member for connecting to the vehicle control surface; first engagement means for selectively engaging and disengaging the first drive device and the output member; a drive arrangement comprising second engagement means for selectively engaging and disengaging said second drive device and said output member; [2] The drive arrangement according to [1], wherein the first engagement means includes at least one actuator configured to engage and disengage the first drive device and the output member. [3] The at least one actuator substantially simultaneously: causing the first engagement means to disengage the first drive device from the output member; The drive structure according to [2], wherein the second engagement means is configured to engage the second drive device and the output member. [4] The drive structure described in [2] or [3], wherein the at least one actuator is configured to cause movement of a rod and a pair of arms attached to the rod. [5] The drive structure described in [4], wherein the actuator, the rod, and the arm are configured to rotate around the first and second drive devices. [6] The drive arrangement of any one of [1] to [5], wherein the first engagement means comprises a clutch-based mechanism. [7] The drive arrangement of any one of [1] to [6], wherein the first engagement means comprises a Hirth coupling. [8] The drive arrangement of any one of [1] to [6], wherein the first engagement means comprises a friction clutch. [9] The drive arrangement of any one of [1] to [8], wherein the first engagement means comprises a first side configured to slide along a splined section of a first output shaft of the first drive device under the action of an actuator to facilitate engagement and disengagement of the first drive device and the output member.

[10] The drive arrangement of any one of [1] to [4], wherein the first engagement means comprises a planetary gear transmission.

[11] The drive arrangement of

[10] , comprising a friction material configured to restrict movement of a ring gear of the planetary gear transmission.

[12] The drive arrangement of

[11] , comprising a rocker configured to apply the friction material to the ring gear.

[13] The drive arrangement of

[11] or

[12] , wherein the friction material is configured to move radially relative to the planetary gear transmission.

[14] The drive arrangement according to any one of

[10] to

[13] , comprising at least one additional gear device.

[15] The drive arrangement according to any one of [1] to [4], wherein the first engagement means comprises a strain wave gear transmission.

[16] The drive arrangement according to

[15] , wherein the strain wave gear transmission includes a variable size wave generator mechanism.

[17] The drive arrangement of any one of [1] to [3], wherein the first drive device is rotatably mounted within a housing on a bearing.

[18] The drive arrangement of

[17] , comprising a torque arm rotatably mounted adjacent to the first drive device, and a force sensor configured to measure a force experienced by the torque arm.

[19] The drive arrangement according to

[18] , wherein the force sensor is mechanically grounded to constrain movement of the force sensor and the torque arm.

[20] The drive arrangement of

[18] or

[19] , comprising a pin configured to be operated by an actuator to constrain the first drive device and the torque arm so that they rotate together.

[21] The drive arrangement according to any one of

[17] to

[20] , wherein the second drive device is rotatably mounted within a housing on a bearing.

[22] The drive arrangement according to any one of

[17] to

[21] , comprising a second actuator.

[23] The drive arrangement of any one of [1] to

[22] , wherein the output member includes a connection portion configured to connect to the vehicle control surface.

[24] The drive arrangement of [1], wherein the first drive unit and the second drive unit are both arranged to be simultaneously engaged with the output member, and the first drive unit and the second drive unit are independently disengageable from the output member to allow the other drive unit to independently control the output member.

[25] A vehicle comprising a drive arrangement according to any one of [1] to

[24] .

Claims

1. 1. A drive arrangement for operating a vehicle control surface, comprising: a first drive unit; a second drive unit; an output member for connecting to the vehicle control surface; first engagement means for selectively engaging and disengaging the first drive device and the output member; second engagement means for selectively engaging and disengaging the second drive device and the output member; the first engagement means including at least one actuator configured to engage and disengage the first drive device and the output member; The at least one actuator simultaneously: causing the first engagement means to disengage the first drive device from the output member; the second engagement means is configured to engage the second drive device with the output member; The at least one actuator is configured to cause movement of a rod and a pair of arms attached to the rod.

2. The drive arrangement of claim 1 , wherein the actuator, the rod, and the arm are configured to rotate about the first and second drive devices.

3. 3. A drive arrangement as claimed in claim 1 or 2, wherein the first engagement means comprises a clutch-based mechanism.

4. 3. A drive arrangement as claimed in claim 1 or 2, wherein the first engagement means comprises a Hirth coupling.

5. 3. A drive arrangement as claimed in claim 1 or 2, wherein the first engagement means comprises a friction clutch.

6. 3. The drive arrangement of claim 1 or 2, wherein the first engagement means comprises a first side configured to slide along a splined section of a first output shaft of the first drive unit under the action of an actuator to facilitate engagement and disengagement of the first drive unit with the output member.

7. 2. The drive arrangement of claim 1, wherein said first engagement means comprises a planetary gear transmission.

8. The drive arrangement of claim 7 , comprising a friction material configured to restrict movement of a ring gear of the planetary gear transmission.

9. The drive arrangement of claim 8 comprising a rocker configured to apply the friction material to the ring gear.

10. 10. A drive arrangement according to claim 8 or 9, wherein the friction material is configured to move radially relative to the planetary gear transmission.

11. The drive arrangement of claim 7 including at least one additional gear arrangement.

12. 3. A drive arrangement as claimed in claim 1 or 2, wherein the first engagement means comprises a strain wave transmission.

13. The drive arrangement of claim 12 , wherein the strain wave transmission includes a variable size wave generator mechanism.

14. A drive arrangement for operating a vehicle control surface, comprising: a first drive unit; a second drive unit; an output member for connecting to the vehicle control surface; first engagement means for selectively engaging and disengaging the first drive device and the output member; second engagement means for selectively engaging and disengaging the second drive device and the output member; a torque arm rotatably mounted adjacent to the first drive device, and a force sensor configured to measure a force experienced by the torque arm; The first drive arrangement is rotatably mounted within a housing on bearings.

15. The drive arrangement of claim 14 , wherein the force sensor is attached to a stationary component and the torque arm to constrain movement of the force sensor and the torque arm.

16. 16. The drive arrangement of claim 14 or 15, comprising a pin configured to be operated by an actuator to constrain the first drive unit and the torque arm so that they rotate together.

17. 16. A drive arrangement according to claim 14 or 15, wherein the second drive is rotatably mounted within a housing on bearings.

18. 16. A drive arrangement according to claim 14 or 15, comprising a second actuator.

19. 15. The drive arrangement of claim 1 or 14, wherein the output member includes a connection portion configured to connect to the vehicle control surface.

20. 15. The drive arrangement of claim 14, wherein the first drive unit and the second drive unit are both arranged to be simultaneously engaged with the output member, and the first drive unit and the second drive unit are independently disengageable from the output member to allow the other drive unit to independently control the output member.

21. A vehicle comprising a drive arrangement according to claim 1 or 14.

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