Patent Publication Number: US-2022234722-A1

Title: Track drive device for an aircraft, a drive arrangement and an aircraft having such a track drive device

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of the German patent application No. 102021101508. 1 filed on Jan. 25, 2021, the entire disclosures of which are incorporated herein by way of reference. 
     FIELD OF THE INVENTION 
     The invention relates to a track drive device for driving a movable component of an aircraft, such as a high-lift device. The invention further relates to a drive arrangement, a wing and an aircraft. 
     BACKGROUND OF THE INVENTION 
     In aviation, numerous different linear geared drives are used to actuate or drive external and internal components of an aircraft. Those components include high-lift devices, intake ducts and their covers, control surfaces, loading ramps, cargo transporters, cargo locks and door latches as well as passenger seats. 
     Desirable properties for these drives include zero backlash, large gear reduction from the input to the output, ability to self-lock, better load transfer and reduced wear. For certain applications, such as the high-lift devices and control surfaces, it is desirable to have a failsafe system design. 
     A linear drive exhibiting at least one of these properties is known from German patent application No. 102021101487.5, whose disclosure is incorporated herein by reference. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved linear drive device exhibiting at least one of these desired properties. 
     The invention provides a track drive device configured for driving a first airfoil relative to a second airfoil between a fully extended and fully retracted position, the linear track drive device comprising
         a track member that extends in a longitudinal direction and includes at least one toothed rack member,   a plurality of support members that are configured to support the track member in a movable manner, and   a drive device configured for driving the track member between the fully extended and fully retracted positions, the driving device having at least one drive unit that is arranged adjacent to the track member,   wherein each drive unit comprises a plurality of engaging members being supported so as to be movable between a fully engaged position, in which the respective engaging member fully engages the toothed rack member, and a fully disengaged position, in which the respective engaging member is fully disengaged from the toothed rack member, and   a rotatable cam member having a control cam portion, the control cam portion being configured so as to, upon rotation of the cam member, sequentially move the engaging members between the fully engaged and fully disengaged positions so as to cause a linear motion of the track member relative to the drive device along the longitudinal direction.       

     Preferably, the drive device includes at least two drive units. 
     Preferably, the drive units are configured such that there is at least one engaging member in the fully engaged position in at least two drive units. 
     Preferably, the drive units are arranged adjacent to each other along the longitudinal direction. 
     Preferably, the drive units are arranged offset from each other in a direction orthogonal to the longitudinal direction. 
     Preferably, the rotatable cam member is configured as a cam shaft and the control cam portion is disposed on a circumferential surface of the cam shaft. Preferably, the cam shaft is configured as a massive shaft and the control cam portion is disposed on the outer circumferential surface of the cam shaft. Preferably, the cam shaft is configured as a hollow shaft and the control cam portion is disposed on the inner circumferential surface of the cam shaft. 
     Preferably, the cam shaft comprises a plurality of cam segments and each cam segment includes a different section of the cam portion. Preferably, the cam segments are rotationally offset in a progressive manner along the axial direction of the cam shaft, so as to generate a wave-like motion of the engaging members along the longitudinal direction. 
     Preferably, the rotatable cam member is configured as a gearwheel and the control cam portion is disposed on a lateral wheel surface. Preferably, the control cam portion is disposed on the gear rim of the gear wheel. Preferably, the control cam portion extends in the circumferential direction of the gear wheel and is spaced apart from the gear wheel center. Preferably, the control cam portion extends along at most three-quarters or at most half of the angular circumference of the gear wheel. 
     Preferably, the respective rotatable cam members are coupled to each other by a torque transmitting member. Preferably, the torque transmission member is configured as a pinion that meshes with the respective rotatable cam members. Preferably, the torque transmission member is an articulated coupling that has a spherical portion and a cavity portion, wherein the spherical portion is arranged on one of the respective cam members and the cavity portion is formed on the other of the respective cam members and the spherical portion is inserted into the cavity portion. 
     Preferably, the engaging members are arranged so as to form at least a first engaging member set and a second engaging member set of engaging members. Preferably, the control cam portion is configured so as to, upon rotation of the cam member, sequentially move engaging members of each engaging member set, wherein a first drive unit comprises the first engaging member set and a second drive unit comprises the second engaging member set. 
     Preferably, when the drive units are arranged on the same side of the track member, the control cam portion is configured such that the engaging members of each engaging member set closest to each other measured along the longitudinal direction are at a different position between the fully engaged and fully retracted positions and/or move in opposite directions. 
     Preferably, when the drive units are arranged on opposing sides of the track member, the control cam portion is configured such that the engaging members of each engaging member set closest to each other measured along the longitudinal direction are at the same position between the fully engaged and fully retracted positions and/or move together towards or away from the track member. 
     Preferably, the track member comprises a toothed rack member on two opposing sides. Preferably, the drive units are arranged on the opposing sides so that each drive unit engages the toothed rack member from the side on which the respective drive unit is arranged. 
     Preferably, the drive units are arranged on the same side of the track member and the drive units are arranged so that each drive unit engages the same toothed rack member from the side on which the drive units are arranged. 
     Preferably, the drive units are arranged outside or inside of a channel defined by the track member. 
     Preferably, the engaging members are configured in a linear arrangement that is aligned parallel to the longitudinal direction. 
     Preferably, at least one engaging member is integrally formed with a membrane member, the membrane member being deformable by the control cam portion so that the engaging members are shiftable between the fully engaged and fully disengaged positions. 
     Preferably, at least one engaging member has an engaging portion that is arranged to contact the toothed rack, and the engaging portion engages the toothed rack in a planar manner Preferably, the engaging portion, when viewed in a cross-section, is shaped as a triangle or an ogive. 
     Preferably, at least one engaging member has a cam contact portion that is arranged opposite of the engaging portion and arranged to contact the cam portion. Preferably, at least one engaging member is formed as a rectangular solid member or as a pin-like member; or wherein at least one engaging member is formed as a circular arc shaped solid member. 
     Preferably, each drive unit supports the cam member and/or the engaging members. 
     Preferably, each drive unit comprises a support member having a plurality of openings, and the engaging members are arranged in the openings so as to be slidable between the fully engaged and fully disengaged positions. 
     Preferably, the track member is configured in a circular arc shape. 
     The invention provides an airfoil arrangement comprising a first airfoil, a second airfoil and a track drive device as previously described, wherein the track member is attached to the first airfoil and the support members and the drive device are attached to the second airfoil, so that the drive device is capable to move the first airfoil between the fully extended and the fully retracted positions. 
     The invention provides a wing for an aircraft comprising a preferred airfoil arrangement, wherein the first airfoil is a high-lift device or a control surface and the second airfoil is a wing box or a leading edge member. 
     The invention provides an aircraft comprising a preferred track drive device and/or a preferred airfoil arrangement and/or a preferred wing. 
     The proposed linear drive has a cam shaft on the input/drive side, which is driven by some kind of power unit, e.g., an electric or hydraulic motor. The cam shaft is preferably seated in a housing and supported by bearing assemblies. The cam on the shaft is continuously located along the whole shaft in a spherical arrangement. Between the cam shaft and the rack multiple teeth are located in openings inside the housing. The teeth are movable relative to the housing. 
     A certain number of these teeth are pressed towards the rack by the cam. Based on the rotational position of the cam shaft different teeth are pressed down and the downwards movement of the tooth can be described by a wave. In that way the down pressed teeth drive the rack along its longitudinal axis. The minimum transmission speed from drive side to linear drive is at least one tooth of the rack per cam shaft rotation. Different transmission ratios are possible when multiple cam segments with offset phases are used. To drive the rack the drive side (preferably including the housing) and the cam shaft are preferably rigidly mounted in relation to the rack in its drive direction. 
     It is also possible that the proposed device has an inverted cam shaft build as hollow shaft with an internal cam that is used to press down multiple teeth. The teeth are mounted in a housing surrounding the piston. The piston is built like a rack with gear teeth. These teeth are continuously formed around the piston main axis. The internal cam geometry in the cam hollow shaft is preferably designed in a spiral form. The movement of the teeth towards the piston build a wave. In that way always a certain number of teeth are engaged and the piston is transported by the teeth in its drive direction. The cam shaft is in main axis direction rigidly connected to the housing and driven by some kind of external powered device. 
     The piston may also be a curved piston. The cam shaft in this case must consist of many segments correlation to the tooth positions. The segments must be coupled rotational to rotate synchronously. 
     While the linear drive device is subsequently described with reference to high-lift devices for the sake of brevity, it should be noted that the linear drive device may also be configured to drive other external movable components or internal movable components of an aircraft. External movable components include high-lift devices, intake ducts and their covers and control surfaces, whereas internal movable components include loading ramps, cargo transporters, cargo locks and door latches as well as passenger seats. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Examples of the invention are subsequently described in more detail with reference to the accompanying drawings. Therein: 
         FIG. 1  depicts an embodiment of an aircraft; 
         FIG. 2  depicts an embodiment of an airfoil arrangement; 
         FIG. 3  depicts the airfoil arrangement of  FIG. 2  in the retracted position; 
         FIG. 4  depicts the airfoil arrangement of  FIG. 2  in the extended position; 
         FIG. 5  depicts an embodiment of a track drive device; 
         FIG. 6  depicts another embodiment of a track device; 
         FIG. 7  depicts another embodiment of an airfoil arrangement; 
         FIG. 8  to  FIG. 12  depict different arrangements of track drive devices; and 
         FIG. 13  depicts another embodiment of an airfoil arrangement; 
         FIG. 14  depicts a detailed view of a track drive device; and 
         FIGS. 15 a  and 15 b    depict a detailed view of a rotatable cam member. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIG. 1 , an exemplary embodiment of an aircraft  10  comprises a fuselage  12  to which a pair of wings  14  is attached. Further attached to the wings  14  is a pair of turbine engines  16 . It should be noted that the number and type of engines may vary. At the rear of the fuselage  12  a horizontal tail plane (HTP)  18  and a vertical tail plane (VTP)  20  are arranged. 
     The wings  14 , the HTP  18  and the VTP  20  have a plurality of control surfaces  22  for steering the aircraft  10 . In addition the wings  14  also include a plurality of high-lift devices  24 , such as slats and flaps. 
     Referring to  FIG. 2  to  FIG. 4 , an airfoil arrangement  26  is depicted. The airfoil arrangement  26  includes a slat  28  as a first airfoil  30  and a wing box or a leading edge member of the wing  14  as a second airfoil  32 . The airfoil arrangement  26  includes a linear track drive device  34  that is configured to drive the first airfoil  30  relative to the second airfoil  32  between a retracted position ( FIG. 3 ) and an extended position ( FIG. 4 ). 
     The track drive device  34  includes a track member  36  extending in a longitudinal direction. The track member  36  comprises a rack member  38  having a plurality of teeth  40 . The track member  36  is mechanically coupled to the first airfoil  30  through a kinetic linkage  42 . 
     The track drive device  34  also includes a plurality of support members  44  that support the track member  36 . The support members  44  may be configured as rollers  45  that are preferably arranged above and below the track member  36 . 
     Referring now to  FIG. 3  to  FIG. 5 , the track drive device  34  includes a drive device  46  for driving the track member  36 . The drive device  46  includes a plurality of drive units  48 , e.g., three drive units  48 . The drive units  48  are arranged along a curved path defined by the track member  36 . 
     As depicted more closely in  FIG. 5 , each drive unit  48  includes a plurality of engaging members  50 . The engaging members  50  are arranged so that they can mesh with the track member  36 , when the engaging members  50  are in their respective fully engaged position. 
     Furthermore, each drive unit  48  has a cam member  52  that is rotatably supported. The cam member  52  has a control cam portion  54  that is formed so that upon rotation of the cam member  52 , the engaging members  50  are sequentially moved between their respective fully engaged and fully disengaged positions. The cam member  52  may be configured as a cam shaft  56 . 
     Adjacent cam members  52  can be configured such that adjacent drive units  48  can be arranged with an angle relative to each other. The cam members  52  are configured such that they can be articulated, in this configuration. 
     The cam member  52  has an input portion  58 . The input portion  58  can be mechanically coupled to a mechanical drivetrain  60  or an adjacent drive unit  48 . The input portion  58  is preferably formed as a hollowed out portion in which the driving component can be inserted. 
     The cam member  52  has an output portion  62 . The output portion  62  can be mechanically coupled to another cam member  52  of another adjacent drive unit  48 . The output portion  62  is preferably formed as an ellipsoidal portion that can be inserted into the input portion  58 . 
     Both the input portion  58  and the output portion  62  may have corresponding meshing teeth. 
     Each drive unit  48  may have a housing  64  which supports the cam member  52  and the engaging members  50 . 
     For a detailed description of the function the track drive device  34  and the cam member  52  reference is made to German patent application No. 1020211101487.5 filed Jan. 25, 2021, specifically  FIG. 3  to  FIG. 10  and the associated description on pages  7  to  11 , the disclosure of which is hereby incorporated by reference. 
     Referring to  FIG. 6 , another embodiment of a track drive device  34  is depicted. It will only be described insofar as it differs from the previously described embodiment. 
     The track device  34  includes a plurality of drive units  48 , e.g., six drive units  48 . In this embodiment, all drive units  48  are supported by a single housing  64 . The housing  64  in this case is configured in a curved manner, so as to follow the path defined by the track member  36 . 
     Referring to  FIG. 7 , another embodiment of an airfoil arrangement  26  is shown. It will only be described insofar as it differs from the previously described embodiment. 
     The track device  34  has again a plurality of drive units  48 , e.g., four drive units  48 . In this embodiment, each drive unit  48  is individually coupled to the drivetrain  60 . The drive units  48  not only follow the path defined by the track member  36  but also are arranged in the upper and lower halves of the track member  36 . 
       FIG. 8  and  FIG. 9  schematically depict a configuration of the track drive device  34  when viewed from the leading edge. The drive units  48  are arranged on opposite sides of the track member  36  that has two rack members  38  attached to it. Upon rotation of the cam member  52  the engaging members  50  move in the same direction, e.g., away from the track member  36  towards disengagement. 
       FIG. 10  schematically depicts a configuration of the drivetrain  60 . A main shaft  66  extends along the inboard-outboard direction and is driven in a manner known per se. Transmission shafts  68  are driven by the main shaft  66  and connect to the drive units  48  as previously described. 
       FIG. 11  schematically depicts another configuration of the track drive device  34 . In this configuration the drive units  48  are stacked in the up-down direction and covered by a single housing  64 . The cam members  52  of the drive units  48  are rotated relative to each other by a predetermined fixed phase angle, e.g., a quarter turn, such that the engaging members  50  move differently. 
       FIG. 12  schematically depicts another configuration of the track drive device  34 . In this configuration, the drive units  48  have engaging members  50  arranged on opposite sides within the track member  36  that are drive by a single cam member  52 . As a result, the phase angle of the engaging members  50  of one side relative to the opposite side is half a turn of the cam member  52 . 
     Referring to  FIG. 13  to  FIGS. 15 a  and 15 b   , another embodiment of an airfoil arrangement  26  is depicted. The airfoil arrangement  26  includes a slat  28  as a first airfoil  30  and a wing box or a leading edge member of the wing  14  as a second airfoil  32 . The airfoil arrangement  26  includes a linear track drive device  34  that is configured to drive the first airfoil  30  relative to the second airfoil  32  between a retracted position and an extended position. 
     The track drive device  34  includes a track member  36  extending in a longitudinal direction. The track member  36  comprises a rack member  38  having a plurality of teeth  40 . The track member  36  is mechanically coupled to the first airfoil  30  through a kinetic linkage  42 . 
     The track drive device  34  also includes a plurality of support members  44  that support the track member  36 . The support members  44  may be configured as rollers  45  that are preferably arranged above and below the track member  36 . 
     The track drive device  34  includes a drive device  46  for driving the track member  36 . The drive device  46  includes a plurality of drive units  48 , e.g., three drive units  48 . The drive units  48  are arranged along a curved path defined by the track member  36 . 
     Each drive unit  48  includes a plurality of engaging members  50 . The engaging members  50  are arranged so that they can mesh with the track member  36 , when the engaging members  50  are in their respective fully engaged position. 
     Furthermore, each drive unit  48  has a cam member  52  that is rotatably supported. The cam member  52  has a control cam portion  54  that is formed so that upon rotation of the cam member  52 , the engaging members  50  are sequentially moved between their respective fully engaged and fully disengaged positions. The cam member  52  may be configured as a gearwheel  156 . The cam portion  54  is arranged on one or both sides of the cam gearwheel  156 . 
     In a variant, the cam member  52  is arranged below the track member  36  and the cam portions  54  on opposite sides of the cam member  52  drive the engaging members  50  ( FIG. 14 ). 
     The cam member  52  has toothed portion  158 . The toothed portion  158  can be mechanically coupled to a mechanical drivetrain  60  or an adjacent drive unit  48  through an intermediate gear  160 . Specifically, the gearwheels  156  mesh with the intermediate gears  160 , one of which is driven by the drivetrain  60 . 
     With the track drive devices  34  described herein, multiple load-paths and thus failsafe capabilities can be implemented for moving airfoils relative to each other. The measures can achieve up to zero backlash, a larger gear reduction from the input to the output compared to known mechanisms, the ability to self-lock, and better load transfer as well as reduced wear due to larger pressure transmission surfaces. 
     In order to provide a track drive device for an aircraft that has zero backlash, a large gear reduction, the ability to self-lock, and a better load transfer and reduced wear, the invention proposes that the track drive device ( 34 ) drives a track member ( 36 ) through a drive device ( 46 ) that has at least one drive unit ( 48 ) that is arranged adjacent to the track member. Each drive unit ( 48 ) comprises a plurality of engaging members ( 50 ) that are driven by a cam shaft ( 56 ) or a cam gear such that the engaging members ( 50 ) are sequentially shifted in a wave-like pattern which results in the track member ( 36 ) being moved in a linear manner relative to the drive device ( 46 ) along a longitudinal direction. 
     While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority. 
     LIST OF REFERENCE SIGNS 
     
         
           10  aircraft 
           12  fuselage 
           14  wing 
           16  turbine engine 
           18  horizontal tail plane (HTP) 
           20  vertical tail plane (VTP) 
           22  control surface 
           24  high-lift device 
           26  airfoil arrangement 
           28  slat 
           30  first airfoil 
           32  second airfoil 
           34  track drive device 
           36  track member 
           38  rack member 
           40  teeth 
           42  kinetic linkage 
           44  support member 
           45  roller 
           46  drive device 
           48  drive unit 
           50  engaging members 
           52  cam member 
           54  cam portion 
           56  cam shaft 
           58  input portion 
           60  drivetrain 
           62  output portion 
           64  housing 
           66  main shaft 
           68  transmission shaft 
           156  cam gear 
           158  toothed portion 
           160  intermediate gear