Patent Publication Number: US-2023151874-A1

Title: Damping device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European Patent Application No. 21306579.0 filed Nov. 12, 2021, the entire contents of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure is concerned with a device for damping rotary motion of a component such as, but not limited to, a rotary actuator. The rotary actuator could for example be a rotary actuator for driving a surface of an aircraft e.g. a flight control surface. 
     BACKGROUND 
     Actuators are used in aircraft to control various moveable components and surfaces including, but not only, flight control surfaces such as spoilers, ailerons and wing flaps. 
     Conventionally, hydraulic actuators have been used in aircraft, whereby a hydraulic piston, connected to the surface, is moved in response to the flow of hydraulic pressure from a hydraulic supply. Whilst hydraulic actuators have been used in aircraft for many years and have many advantages, such systems are fairly heavy and bulky. As the actuators are supplied from the aircraft supply, often a large plumbing network is required to deliver the pressure to distributed actuators, and the level of reliability is low. Local hydraulically powered actuators cannot easily be provided at aircraft wing ends etc. especially on so-called ‘thin wing’ aircraft. Further, hydraulic systems are prone to leakage and require seals and connectors, which all add to the size and weight of the system. 
     There is now a trend in the aircraft industry towards More Electric Aircraft (MEA) and, more recently, to All Electric Aircraft (AEA) with the objective being to replace hydraulic systems and parts with electrical systems and parts. Electric systems can be smaller and lighter and are generally ‘cleaner’ than hydraulic systems. This leads to the use of electromechanical actuators which may be fully rotary. There is therefore a need to provide an end stop device suitable for use with a rotary electromechanical actuator for primary flight controls in an aircraft. 
     SUMMARY 
     From a first aspect, the disclosure provides a device for damping rotary motion of a component. The device includes a first part adapted to be mounted to the component so as to rotate therewith; and a second part adapted to be fixed such that the first part moves towards the second part when the component rotates in a first direction. The at least one surface of the first part and a corresponding at least one surface of the second part are angled such that, as the first part moves towards the second part, the at least one surface of the first part will move into contact with and then move along the corresponding at least one surface of the second part such that friction between the at least one surface of the first part and the corresponding at least one surface of the second part acts against the movement of the first part. 
     In a device according to any example of the disclosure, the first part may be symmetrical about an axis extending in the first direction and may comprise a body having a first angled surface formed on a first side thereof and a second angled surface formed on a second, opposite side thereof. 
     In a device according to any example of the disclosure, the second part may comprise first and second side portions extending in the first direction, wherein a respective angled surface is formed at a first end of each of the first and second side portions, wherein the respective angled surfaces of the first part and the second part are angled such that rotation of the component in the first direction will cause the angled surfaces of the first part to slide along the angled surfaces of the second part. 
     In a device according to any example of the disclosure, the second part may further comprise an end portion extending between the first and second side portions. 
     The end portion and the first and second side portions may form a U shape. 
     In a device according to any example of the disclosure, the first part may further comprise an end stop portion configured to move into contact with and be stopped by the second part after the at least one surface of the first part moves into contact with and then moves along the corresponding at least one surface of the second part. 
     In a device according to any example of the disclosure, the end stop portion may extend along the axis and may have an end configured to abut against the end portion to stop rotation of the first part relative to the second part. 
     A device according to any example of the disclosure may further comprise one or more support beams configured to absorb kinetic energy from the moving first part and to support the second part in a fixed position. 
     In a device according to any example of the disclosure, the at least one surface of the first part and the corresponding at least one surface of the second part may extend at an angle of between 30° and 60° to the direction of rotation. 
     From a further aspect, the disclosure provides an apparatus that includes a device as described in any previous example; a rotary component; and a fixed component. The rotary component is adapted to rotate relative to the fixed component. The first part of the device is fixed to the rotary component, and the second part of the device is fixed to the fixed component. 
     In an apparatus according to any example of the disclosure, the rotary component and the fixed component may be parts of a rotary actuator. 
     In an apparatus according to any example of the disclosure, the rotary actuator may be an electromechanical rotary actuator. 
     From a still further aspect, the disclosure may provide an aircraft control surface assembly comprising a flight control surface and an apparatus as in the above examples to move the flight control surface. 
     In any example of the disclosure, the flight control surface may be a spoiler. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       Examples of the invention will now be described, by way of example only, with reference to the drawings in which: 
         FIG.  1    is a schematic cross section view through part of an aircraft wing; 
         FIG.  2    is a perspective view of a rotary actuator according to an example of the disclosure; 
         FIG.  3    is a side on view of the rotary actuator of  FIG.  3   ; 
         FIG.  4    is a section along line A-A of  FIG.  3   ; and 
         FIG.  5    is a schematic plan view of a device according to an example of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed towards a device for damping rotary motion of a component. The device could be used in any number of examples such as, in rotary actuators for use in vehicles or machinery. Further, the device could potentially be used with many other components (other than actuators) which rotate relative to another structure. 
     Referring to  FIG.  1   , this shows a possible example actuator for a control surface in a wing of an aircraft (not shown) with which the device according to the disclosure could be used. An aircraft wing  2  typically comprises a hollow section S and extends outwardly from a body (not shown) of the aircraft. 
     A number of control surfaces are typically provided on the wing  2 . In the example shown, a control surface  4  is a spoiler provided adjacent an outer end  6  of the wing  2  (in other words, the end of the wing which is furthest from the aircraft body). The control surface  4  is configured to rotate about a hinge  8  in the wing  2  to move relative to the wing when actuated. The rotation of the control surface  4  is configured to alter the speed, altitude and/or direction of movement of the aircraft in flight or on the ground. In the example shown, the hinge  8  is located in the wing  2  and the control surface  4  extends outwardly from the hinge  8  and from the end of the wing to taper to a tip portion  10 . It will be appreciated however that the control surface  4  may have any desired configuration and any desired location on an aircraft wing  2  depending on the design and intended use thereof. 
     A rotary actuator  12  is provided which is configured to move the control surface  4  to rotate about the hinge  8  in either a clockwise or anti-clockwise direction as required. Thus, the control surface  4  may be rotated to be in line with the wing  2  as shown in  FIG.  1   , to be angled such that the tip portion  10  extends above the wing  2  or to be angled such that the tip portion  10  extends below the wing  2 . A control system (not shown) may be provided to control the rotary actuator  12 . 
     As seen in  FIG.  1   , the rotary actuator  12  is sized so as to be housed within the hollow section of the wing  2  and or the control surface  4 . In some examples, the rotary actuator is an electrical rotary actuator. The rotary actuator  12  is fixed relative to the wing  2  or the aircraft structure so as to provide a rotary drive output relative thereto. In the example shown, the rotary actuator  12  is mounted via a connection mechanism  14  (such as brackets for example) to the rear spar  16  of the wing  2 . The rotary output of the rotary actuator  12  can be connected to a rod which is adapted to push against the control surface  4  or, as in the example of  FIG.  1   , the rotary output of the rotary actuator  12  can be directly connected to the control surface to rotate the control surface  4  about the hinge  8 . 
     It will be appreciated that in many examples, including the example of  FIG.  1   , it is necessary to accurately control the movement of the rotary output of the rotary actuator  12  such that the movement thereof can be stopped accurately at the correct end position. In examples for use in controlling control surfaces, it will be appreciated that it is desirable for the control surface movements to be very accurately controlled. Especially when a high gear ratio is used within the rotary actuator, the inertia of the rotary output of the rotary actuator  12  may be significant and so a means of dissipating the kinetic energy of the rotary output of the rotary actuator to bring the actuator to a stop in a timely and accurate manner is required. This may be difficult to achieve, for example in aerospace applications where it is important to keep the weight of all components to a minimum and where there may be limited space available, for example in thin wing aircraft environments. 
     Referring now to  FIGS.  2  to  4   , an exemplary rotary actuator including a device according to one example of the disclosure is shown.  FIG.  3    is a side view of an electrical rotary actuator  12 , for example for use with an aircraft control surface  4  as in the example of  FIG.  1   . 
     As seen in  FIG.  3   , in some examples the device according to the disclosure may be used with a rotary actuator such as an electrical rotary actuator. In some examples, the electrical rotary actuator may be for use in controlling a control surface  4  of an aircraft as described above. The rotary actuator  12  comprises a component  18  which is adapted to be driven to rotate about an axis X-X to form a hinge (thus forming a rotary output of the rotary actuator). The component  18  is annular in the example shown, the annular component  18  extending around and being centred on the axis X-X. 
       FIG.  4    is a vertical cross section through the rotary actuator of  FIG.  3    taken along line A-A, i.e. through the component  18 . As seen in  FIG.  4   , the component  18  is mounted via gears  20  to a rotary drive shaft  22  driven by an electric motor (not shown). The longitudinal axis of the rotary drive shaft  22  corresponds to the axis X-X about which the annular component  18  extends. The gears  20  may take any suitable form to provide the required torque to move the control surface  4 . In one example, a planetary gear mechanism may be used. 
     The component  18  is adapted to rotate when driven by the drive shaft  22  and electric motor (not shown). A housing  24  may be provided for the component and may be fixed such that the component  18  rotates relative to the fixed housing  24  when driven by the motor. In the example shown, the housing  24  is cylindrical and is formed in two parts (first part  24   a  and second part  24   b ) which extend on either axial side of the annular component  18 . The housing  24  and the annular component  18  are coaxial and have the same diameter (D) in the example shown such that the outer surface  26  of the housing  24  is approximately flush with the outer surface  28  of the annular component  18 . 
     In the example shown, the housing  24  is mounted to a fixed structure, for example the rear spar  16  of an aircraft wing  2 . In the example shown, one or more first brackets  30  are attached to the first part  24   a  for fixing the first part  24   a  of the housing  24  to a fixed structure and one or more second brackets  32  are attached to the second part  24   b  for fixing the second part  24   b  of the housing  24  to the fixed structure. Any suitable type of bracket may be provided and these may be integrally formed with the housing  24  or attached to the housing, for example by welding. The first and second brackets  30 ,  32  may be fixed to the fixed structure by any suitable means, for example by rivets or bolts extending through the brackets  30 ,  32  and the rear spar  16 . 
     Thus, in use the rotary actuator of  FIGS.  2  to  4    may be mounted to the rear spar  16  such that the housing  24  is fixed against rotation. When the rotary actuator is actuated, the component  18  will therefore be driven to rotate relative to the housing  24 . In this example, a link  34  is fixed to the annular component  18  so as to rotate therewith and the link  34  is configured to drive movement of the control surface  4  as required when fixed to the control surface. 
     The component  18  of the rotary actuator will typically be configured to rotate through its stroke to a desired position relative to the housing  24 . Thus, the component  18  may rotate between a first position (which is referred to here as 0°) at which the link  34  is in its resting position and a final maximum position at which the link  34  is rotated through a desired angle for a particular aircraft control surface. In one example, the component  18  may be configured to rotate through a maximum stroke of 300°. In another example the component  18  may be configured to rotate through a maximum stroke of 180° or less. In some examples, the component  18  may be configured to be able to rotate in either direction, so as to rotate away from the rest position at 0° in a clockwise or anti clockwise direction and then to rotate back to 0° in the other of the clockwise or anti clockwise directions as required. 
     To avoid potential damage to the control surface or other parts of the aircraft, it is desirable to be able to accurately stop the movement of the component  18  at the end of its stroke, for example at its final maximum position. To achieve this, a device according to the disclosure may be used. It will be appreciated however that such a device could be used in many other applications as will become more apparent from the following description. 
     As seen for example in  FIGS.  3 ,  4  and  5   , the device  50  according to the disclosure comprises a first part  52  mounted to the component  18  to rotate therewith. In the example shown, the first part  52  is formed as an integral part of the component  18 , that is the first part and the component  18  are machined or cast as a single structure. In other examples, the first part  52  can be a separate part which is fixed to the component  18  by brazing or welding for example. 
     The device  50  also comprises a second part  54  which is fixed such that the first part  52  moves towards the second part  54  when the component  18  rotates. In the example of  FIG.  3   , the second part  54  is fixed to the housing  24 . It will be appreciated however that in other examples, the second part can be fixed against rotation in many other ways such as, for example, by fixing the second part to another fixed structure such as a fixed part of an aircraft structure. 
     The device  50  is configured such that the first part  52  and the second part  54  have a respective angled surface configured such that, as the first part  52  moves towards the second part  54  when the component  18  rotates, the surface of the first part  52  will move into contact with and then move along the corresponding surface of the second part  54  such that friction between the surface of the first part and the corresponding surface of the second part acts against the movement of the first part. Thus, the friction will act to slow and/or stop the rotation of the component  18 . 
     In the example shown, the first part  52  comprises a body made up of a base portion  56  and a mid-portion  58 . The first part  52  further comprises an end-stop portion  60 . The base portion  56  is rectangular in plan view and has a first width wb. The mid-portion  58  is trapezoid in plan view and extends from the base portion  56 . The mid-portion  56  has a width wm which is equal to the width wb of the base portion  56  at a first end thereof and is less than the width wb of the base portion  56  at a second opposite end thereof such that the first end of the mid-portion  56  is joined with the outer edges  62  of the base portion  56 . The trapezoid mid-portion  56  therefore has angled side walls  63  which extend between the outer edges  62  of the base portion  56  and the end-stop portion  60 . The end-stop portion  60  extends from the mid-portion  56 , is rectangular in plan view and has a width we which is less than the width wm of the mid-portion where the mid-portion and the end-stop portion join. 
     In the example shown, the first part  52  extends radially outwardly from a radially outer surface  64  of the component  18  to an outer surface  66  of the first part  52 , defining a depth of the first part  52 . The first part  52  extends along a portion of the circumference of the component  18  from a first end  68  of the base portion  56  to a second end  70  of the end-stop portion  60 . In one example, the first part  52  may be configured to extend over a portion of the circumference of the component  18 , for example over between about one twentieth of the circumference of the component  18 . 
     In the example shown, the first width wb of the base portion  56  corresponds to the width or the axial dimension of the component  18 . Further, although the depth of the first part  52  could be constant, in the example shown, the depth of the first part has a first constant value d 1  over the end-stop portion  60  and the mid-portion  56 . The base portion  56  is then configured to taper from the mid-portion  56  to the first end  68  thereof such that the depth d 2  of the base portion  56  at the first end  68  thereof is less than d 1 . 
     The second part  54  of the device  50  is configured to receive the first part  52  and, in the example shown, is made up of an end portion  74  and respective opposed side portions  76 ,  78  extending away from the end portion  74  so as to form a U-shape in plan view. 
     In the example shown, the second part  54  extends radially outwardly from the radially outer surface  80  of the first part  24   a  and the second part  24   b  such that the end portion  74  extends across the component  18  and the respective opposed side portions  76 ,  78  extend in the circumferential direction. The second part  54  extends radially outwardly to an outer surface  82  of the first part  54 , defining a depth d 3  of the second part  54 . In the example shown, the depth d 3  of the second part  54  is constant. 
     The second part  54  extends along a portion of the circumference of the housing  24  from a first end  84  of the end portion  74  to the opposite, free ends  86  of the respective opposed side portions  76 . The second part  54  may further include support beams  88 . The support beams may be joined to and extend beyond the first end  84  of the end portion  74  to extend away from the second part  54 . In some examples, the support beams  88  may be joined to the housing  24  using screws or pins. The support beams  88  may act to absorb kinetic energy from the moving first part in use and to support the second part on the housing  24 . In one example, the second part  54  may be configured to extend over about one sixth of the circumference of the housing  24 . 
     As seen for example in  FIG.  5   , the axially inner corners of the free ends  86  of the respective opposed side portions  76 ,  78  are cut away to form angled surfaces  90 ,  92  extending inwardly towards the end portion  74 . The second part is positioned on the housing  24  such that, as the component  18  is rotated in a first direction, the first part  52  will rotate towards the second part  54  such that the end-stop portion  60  of the first part  52  is at least partially received within the respective opposed side portions  76 ,  78  of the second part  54 . As the component  18  continues to rotate in the first direction D 1 , the angled surfaces  90 ,  92  of the second part  54  will be brought into contact with the angled side walls  63  of the first part  52 . The angled surfaces  90 ,  92  of the second part  54  and the angled side walls  63  of the first part  52  are angled such that further rotation of the component in the first direction will cause the angled side walls  63  to remain in engagement with and slide along the angled surfaces  90 ,  92 . A resultant frictional force between the angled side walls  63  and the angled surfaces  90 ,  92  will act against the rotation of the component  18  (and the first part  52 ) in the first direction D 1 , thus acting to slow or damp the motion of the component  18  in the first direction D 1 . 
     In some examples, the resultant frictional force between the angled side walls  63  and the angled surfaces  90 ,  92  may be sufficient to damp or stop the motion of the component  18 . However, the device  50  of the example shown further comprises an end stop to fully stop the movement of the component  18  relative to the housing  24  at a desired rotation. The end stop is provided by the second end  70  of the end-stop portion  60  of the first part  52  coming into contact with and abutting against the end portion  74  of the first part  54 . In the example shown, the motion of the component  18  relative to the housing will have been slowed significantly due to friction before the end stop portion  60  comes into contact with the end portion  74 , thus reducing the impact which the end portion  74  must be capable of withstanding. Further, the device  50  according to the disclosure is capable of stopping rotation of a component  18  such as the output of a rotary actuator in a very short time. In one example, the device can be used to stop a rotary actuator having an initial speed of 100°/s and an inertia of 5 kg.m2 in less than 10 ms and over a stroke of less than 1°. 
     It will be appreciated that the amount of damping provided by the device  50  and the exact point of rotation at which the rotation of the component  18  is stopped may be varied by any of: varying the position of the first and or second parts  52 ,  54  relative to each other, by varying the dimensions of the end stop portion, by varying the angle at which the angled side walls  63  and/or the angled surfaces  90 ,  92  extend, by varying the materials and/or surface roughness of all or one or more parts of the first and second parts  54 . 
     In one example of the disclosure, the angled side walls  63  may extend at an angle of between 20° and 70° to the circumferential direction, where the circumferential direction may correspond to the direction of rotation. In another example of the disclosure, the angled side walls  63  may extend at an angle of between 30° and 60° to the circumferential direction. In a still further example of the disclosure, the angled side walls  63  may extend at an angle of between 40° and 50° to the circumferential direction, for example at about 45° to the circumferential direction. It will be understood that the angled surfaces  90 ,  92  at least approximately mirror the angled side walls  63  to allow the angled side walls  63  to move across the angled surfaces  90 ,  92  as the first part  52  moves towards the second part  54 . 
     The first and second parts  52 ,  54  of the device  50  could be made of any suitable materials. In some examples, for example for use in aerospace applications, the first and second parts are both made of steel. 
     It will be appreciated by those skilled in the art that the disclosure has been illustrated by describing one or more examples thereof, but is not limited to these examples; many variations and modifications are possible, within the scope of the accompanying claims. In some examples therefore, a first device may be provided for slowing or stopping rotation of a component at the end of its stroke in a first direction and a second device may be provided for slowing or stopping rotation of the component at the end of its stroke in a second, opposite direction. Further, although the device shown in  FIGS.  2  to  5    comprises a U-shaped part having an angled surface on either side thereof, it will be understood that in some examples, only one single angled surface could be provided on the first part to interact with and slide along a single angled surface provided on the second part.