Abstract:
A method for providing torque to assist in moving a component of a mobile platform. Biasing forces may be applied to opposing portions of a torque transferring member that enable the torque transferring member to be maintained in a position of equilibrium. A torque may be applied to one of the component and the torque transferring member such that the biasing forces cooperatively exert a torque on the torque transferring member to assist in moving the torque transferring member out from the position of equilibrium. Motion of the torque transferring member out from the position of equilibrium may be used to assist in moving the component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 10/909,784, filed Jul. 30, 2004, which claims priority to U.S. Provisional Application No. 60/491,075, filed on Jul. 30, 2003. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to systems for providing a torque to move an object that needs to be rotated, and more particularly to an energy shuttle apparatus and method that converts linear motion into a rotary motion for providing a torque to a component that is required to be rotated or twisted. 
       BACKGROUND 
       [0003]    The ability to controllably twist or bend a wing, airfoil or rotorcraft blade, during various phases of flight of an aircraft or rotorcraft, has been a goal of design engineers for some time. The ability to controllably twist or deform a wing, air foil, rotorcraft blade, etc. during various phases of flight can significantly enhance the performance of an aircraft or rotorcraft. 
         [0004]    A major obstacle to implementing actuators or other devices that are designed to twist a wing of an aircraft, a blade of a rotorcraft, etc. is that the actuator or other device used for this purpose must overcome the inherent structural stiffness of the material used to form the wing or rotorcraft blade. This limitation has required that such actuators or other like devices be physically large in relation to the wing or rotorcraft blade which they are associated with, as well as expensive, and further require a significant degree of power to overcome the structural stiffness of the structure which needs to be twisted or flexed. 
         [0005]    Accordingly, there still exists a need in the art for a relatively lightweight, compact apparatus capable of being integrated for use with an air foil, wing, rotorcraft blade, etc. that can twist or deform the air foil, wing or rotorcraft blade as needed, and which further does not require the use of large actuators. 
       SUMMARY 
       [0006]    In one aspect the present disclosure relates to a method for providing torque to assist in moving a component of a mobile platform. The method may comprise applying biasing forces to opposing portions of a torque transferring member to exert forces on the torque transferring member that enable the torque transferring member to be maintained in a position of equilibrium. A torque may be applied to one of the component and the torque transferring member such that the biasing forces cooperatively exert a torque on the torque transferring member to assist in moving the torque transferring member out from the position of equilibrium. Motion of the torque transferring member out from the position of equilibrium may be used to assist in moving the component. 
         [0007]    In another aspect the present disclosure relates to a method for providing a torque to a component of an airborne mobile platform to assist in moving the component. The method may comprise coupling a torque transferring member to the component. A biasing member may be disposed under one of compression and tension relative to the torque transferring member to exert a force that acts on the torque transferring member when the torque transferring member is moved from a first position of equilibrium, wherein the component experiences no rotation causing force from the torque transferring member, to a second position wherein the torque transferring member exerts a torque on the component. An actuator may be used to initiate movement of one of the torque transferring member and the component to urge the component into the second position, wherein the force from the biasing member assists in urging the torque transferring member to move rotationally, to cause movement of the component to the second position. 
         [0008]    In another aspect the present disclosure relates to a method for moving a flight control structure on an airborne mobile platform between first and second positions in a manner that overcomes an inherent structural stiffness of the structure. The method may involve coupling at least one end of a force transferring member fixedly to the structure. A biasing element may be loaded, while the structure is being held in the second position, with a force sufficient to substantially hold the structure in the second position. Energy stored in the biasing element may be used to move the torque transferring member so as to assist in moving the structure from the first position to the second position when movement of the structure is initiated by an external component, to thus substantially transfer the stored energy of the biasing element to the structure through the torque transferring member. The biasing element may be used to again store the energy when the structure is moved from the second position back to the first position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a side view of an apparatus in accordance with a preferred embodiment of the present disclosure; 
           [0011]      FIG. 2  is a simplified plan view of a portion of a wing showing the apparatus incorporated in the wing; 
           [0012]      FIG. 3  is a view of the apparatus imparting a torque to a torque tube to twist the wing of  FIG. 2 ; 
           [0013]      FIG. 4  is a side view of the tension adjuster; 
           [0014]      FIG. 5  is an end view of the tension adjuster taken in accordance with directional line  5 - 5  in  FIG. 4 ; 
           [0015]      FIG. 6  is a side view of the end guide; 
           [0016]      FIG. 7  is a front view of the end guide; 
           [0017]      FIG. 8  is an end view of the spring guide; 
           [0018]      FIG. 9  is a side view of the spring guide taken in accordance with directional line  9 - 9  in  FIG. 8 ; 
           [0019]      FIG. 10  is an end view of the end cap of  FIG. 1 ; 
           [0020]      FIG. 11  is a side view of the center support; 
           [0021]      FIG. 12  is a front view of the center support taken in accordance with directional line  12 - 12  in  FIG. 11 ; 
           [0022]      FIG. 13  is a front end view of the end bearing; 
           [0023]      FIG. 14  is a side view of the end bearing taken in accordance with directional line  14 - 14  in  FIG. 13 ; 
           [0024]      FIG. 15  is a rear end view of the end bearing taken in accordance with directional line  15 - 15  in  FIG. 14 ; 
           [0025]      FIG. 16  is a plan view of the end link; 
           [0026]      FIG. 17  is a side view of the end link taken in accordance with directional line  17 - 17  in  FIG. 16 ; 
           [0027]      FIG. 18  is a side view of the center link; 
           [0028]      FIG. 19  is a plan view of the center link taken in accordance with directional line  19 - 19  in  FIG. 18 ; 
           [0029]      FIG. 20  is an end view of the torque tube; 
           [0030]      FIG. 21  is a side view of the torque tube; 
           [0031]      FIG. 22  is an end view of the housing; 
           [0032]      FIG. 23  is a side view of the housing taken in accordance with directional line  23 - 23  in  FIG. 22 ; 
           [0033]      FIG. 24  is a cross-sectional side view of the end members secured to the housing; 
           [0034]      FIG. 25  is a plan view of one of the end members; 
           [0035]      FIG. 26  is a side view of the end member of  FIG. 25  taken in accordance with directional line  26 - 26  in  FIG. 25 ; 
           [0036]      FIG. 27  is a side view of the outer bearing member; 
           [0037]      FIG. 28  is an end view of the outer bearing member taken in accordance with sectional line  28 - 28  in  FIG. 27 ; 
           [0038]      FIG. 29  is side view of the inner bearing member; 
           [0039]      FIG. 30  is an end view of the inner bearing member taken in accordance with directional line  30 - 30  in  FIG. 29 ; 
           [0040]      FIG. 31  is a plan view of the inner bearing member taken in accordance with directional line  31 - 31  in  FIG. 30 ; 
           [0041]      FIG. 32  is a simplified diagram of the apparatus of the present disclosure to aid in understanding the pertinent formulas dealing with the torque generated by the apparatus; 
           [0042]      FIG. 33  is a graph of the energy stored in the torque tube in relation to the biasing force of the biasing assembly; 
           [0043]      FIG. 34  is a graph of the energy required to return the torque tube to its position of equilibrium; and 
           [0044]      FIG. 35  is a view of the apparatus shown in  FIG. 1  but incorporating coil springs instead of Belleville washers. 
       
    
    
     DETAILED DESCRIPTION 
       [0045]    The following description of various embodiment(s) is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. 
         [0046]    Referring to  FIG. 1 , there is shown an apparatus  10  in accordance with a preferred embodiment of the present disclosure. The apparatus is useful for storing energy that can be “shuttled” between it and a structure such as a wing, airfoil, or rotorcraft blade to provide a twisting force (i.e., torque) to assist in twisting the wing, air foil, rotorcraft blade or any other structure requiring a bending or twisting force to be applied thereto. It is anticipated that the apparatus  10  will find significant utility in aircraft and aerospace applications where it is highly desirable to flex or twist a wing, air foil or rotorcraft blade during various phases of flight. However, the apparatus  10  may be adapted for use with virtually any structure that requires that its structural stiffness be overcome during twisting, bending or other movement thereof. 
         [0047]    With reference to  FIG. 1 , the apparatus  10  generally includes a first assist assembly  12 , a torque tube assembly  14 , and a second assist assembly  16  which is identical in construction to the first assist assembly  12 . However, it will be appreciated immediately that the present disclosure  10  can be implemented with only one of the assist assemblies  12  or  14  if desired, but will obviously provide only one-half of the torque that would be provided with both of the assist assemblies  12  and  16 . 
         [0048]    Since assist assemblies  12  and  16  are identical in construction, only the construction of assist assembly  12  will be described. Assist assembly  12  includes a tension adjuster  18 , an end cap  19 , an end guide  20 , a spring guide  22 , a biasing member or assembly  24 , an end bearing  26 , a center support  28  and a linkage assembly  30 . Components  18 - 30 , as well as the torque tube assembly  14 , are disposed within a tubular housing  32 . The housing  32  is supported within or adjacent the structure to be twisted or deformed, as will be explained in greater detail in the following paragraphs. 
         [0049]    Referring to  FIGS. 1 ,  4  and  5 , the tension adjuster is shown in greater detail. The tension adjuster includes a preferably hex shaped shaft  34  on which a suitable wrench can be used to rotate the tension adjuster  18 . The shaft  34  has a bore  35 . A main body  36  has a mid flange  38  and an inside flange  40 . The main body  36  also includes an opening  42  that communicates with bore  35 . 
         [0050]    Referring to FIGS.  1  and  6 - 7 , the end guide  20  can be seen to include a bore  44 . The end guide  20  further includes relief areas  46  for reducing weight. The end guide  20  fits over the outer surface of inside flange  40  of tension adjuster  18  such that the end guide  20  is supported on the inside flange. 
         [0051]    Referring to  FIGS. 1 ,  8 - 10 , the spring guide  22  includes a body  48  having a flange  50  and a bore  52 . A portion of the body  48  extends within the bore  44  of the end guide  20  and is free to slide therewithin linearly (i.e., horizontally) in the drawing of  FIG. 1 . 
         [0052]    With further reference to  FIG. 1 , the biasing assembly  24  is illustrated as a plurality of Belleville washers stacked one against another. However, it will be appreciated that a coil spring  24 ′ or other suitable biasing element could just as readily be incorporated, as shown in  FIG. 35 . The Belleville washers, however, are particularly advantageous in that they provide a non-linear spring rate. The biasing assembly  24  thus serves to exert a biasing force that tends to urge the spring guide  22  to the right in the drawing of  FIG. 1 . 
         [0053]    Referring to  FIGS. 1 and 10 , the end cap  19  includes a threaded bore  54  and a threaded internal recess  56 . The threaded internal recess  56  fits over a threaded outer end  58  of the housing  32  to affix the end cap  19  to an end of the housing  32 . The threaded bore  54  receives the threaded main body  36  of the tension adjuster  18 . The position of the tension adjuster  18  can thus be adjusted by rotating with a suitable tool the hex shaped shaft  34 , which causes the end guide  20  to be urged over the spring guide  22  which compresses the biasing assembly  24 . In this manner, the biasing force exerted against the flange  50  of the spring guide can be adjusted. 
         [0054]    Referring to  FIGS. 11 and 12 , the center support  28  can be seen to include a main body  60  having a protruding portion  62 . A bore  64  extends through the main body  60  and portion  62 . A plurality of holes  66  are preferably provided for weight reduction. 
         [0055]    Referring to  FIGS. 13-15 , the end bearing  26  can be seen. End bearing  26  includes a shaft  70  extending from a body  68 . A mounting portion  71  having a bore  72  is also formed to extend from the body  68 . A hole  73  extends through the mounting portion  71 . 
         [0056]    With further reference to FIGS.  1  and  13 - 15 , the shaft  70  of the end bearing  26  extends into the bore  52  of the spring guide  22 , while the body  68  extends within the bore  64  of the center support  28 . 
         [0057]    Referring to  FIGS. 16 and 17 , an end link  74  associated with the linkage assembly  30  of  FIG. 1  can be seen in greater detail. The end link  74  comprises an H-shaped component having arms  76  which include openings  78  and  80  formed therein. Openings  78  are aligned to receive a dowel pin  80  ( FIG. 1 ) for coupling the end link  74  to the mounting portion  71  of the end bearing  26 . Thus, the end link  76  is free to pivot about the mounting portion  71 . 
         [0058]    With reference to  FIGS. 1 ,  18  and  19 , a portion of the torque tube assembly  14  can be seen in the form of a center link  82 . The center link  82  includes a hex-shaped opening  84  and a pair of bores  86  on opposite sides of the hex-shaped opening  84 . One of the bores  86  fits between one pair of the arms  76  of the end link  74  and is held therein by a dowel pin  88  ( FIG. 1 ) that extends through openings  80  ( FIG. 16 ) to pivotally couple the center link  82  to the end link  74 . The other bore  86  is identically coupled to the end  74  link of the second assist assembly  16 . 
         [0059]    Referring to  FIGS. 20 and 21 , a torque tube  90  associated with the torque tube assembly  14  is shown. Torque tube  90  includes a hex-shaped outer surface and a bore  92  formed to reduce the weight of the torque tube  90 . The torque tube  90  is slidably received within the hex-shaped opening  84  of the center link  82 . Referring briefly to  FIG. 1 , the torque tube  90  also extends out through an opening  94  in the housing  32 . Thus, the torque tube  94  extends normal to the direction of motion of the end bearing  26 . 
         [0060]    Referring now to  FIGS. 22 and 23 , the housing  32  will be described in greater detail. In addition to the opening  94 , the housing  32  includes an inner bore  96  extending entirely through its length with a reduced diameter section  98  along a mid portion thereof. Reduced diameter area  98  thus forms a pair of steps  100  internal to the housing  32 . Each step  100  abuts one of the center supports  28  of the apparatus  10 . End guide  20  ( FIG. 1 ) is further dimensioned to fit within bore  96  so as to be able to move slideably within the bore  96 . On opposite sides of the bore  94  are a pair of openings  102 . Another pair of openings  104  are provided outside of openings  102 . Still another plurality of bore openings  106  are provided about the opening  94 . Openings  102 ,  104  and  106  all extend through to the back (i.e., hidden from view) side of housing  32  so as to allow fastening elements such as dowel pins or threaded fasteners to extend entirely through the housing  32 . 
         [0061]    Referring now to  FIGS. 24-26 , the use of a pair of end members  108  can be seen. In  FIG. 24 , the end members  108  are shown secured to the housing  32 . End member  108  essentially forms a support to assist in holding the torque tube  90  and to prevent “bowing” of the torque tube in response to torque applied by the linkage assembly  30 . The end member  108  is shown in detail in  FIGS. 25 and 26  and includes face portions  110  which each include an opening  112 . Dowel pins or other like securing members (not shown) extend through the openings  112  and are used to secure the face portions  110  to the outer surface of the housing  32  perpendicularly to the housing. The end member  108  further includes a bore  114  which extends through the end member. A reduced diameter portion  116  ( FIG. 26 ) of the bore  114  forms an internal circumferential shoulder. Holes  116  are formed on opposite sides of bore  114  and align with openings  102  in the housing  32  shown in  FIG. 23 . Dowel pins or like elements (not shown) extend through holes  116  and through openings  102  in the housing  32  to help secure the end member to the housing  32 . 
         [0062]    Referring now to  FIGS. 27-30 , an outer bearing member  120  ( FIGS. 27 and 28 ) and an inner bearing member  122  ( FIGS. 29-31 ) are shown. The outer bearing member  120  includes a body  124  and a flange  126 . Body  124  includes an opening  128  extending therethrough. The inner bearing member  122  ( FIGS. 29-31 ) includes a neck  130  and a body  132 . A bore  134  extends through the length of the inner bearing member  122  and a threaded set screw opening  136  opens into the bore  134 . Neck  130  fits within the bore  128  of the outer bearing member  120  and the body  132  of the inner bearing member  122  abuts the flange  126  of the outer bearing member  120  as shown in  FIG. 24 . The bore  134  is further hex-shaped, as seen in  FIG. 30 . This hex-shaped bore  134  receives the torque tube  90  therethrough and thus provides support, in combination with the end member  108 , to prevent bowing of the torque tube. 
         [0063]    One implementation of the apparatus  10  is shown in  FIG. 2  in simplified form. The torque tube  90  extends within a rotorcraft blade  138  from approximately a root portion  140  of the blade to a tip portion  142  thereof. A suitable supporting structure  144  is disposed within the blade  138  at the tip portion  142  to affix the outermost end  90   a  of the torque tube  90  to the blade  138 . A bearing assembly  146  is disposed within the blade  138  near the root portion  140 . The housing  32  is also secured to an interior area  146  of the blade  138 . Alternatively, the housing  138  can be secured to spars or other structural elements inside a wing or airfoil. An actuator  148  is mechanically coupled to the torque tube  90  and is used to initiate rotational movement of the torque tube  90 . However, due to the significant mechanical energy stored by the biasing assemblies  24 , the actuator  148  is able to rotate the torque tube  90  using only a small fraction of the force that would otherwise be required from the actuator  148 . Put differently, the apparatus  10  provides the great majority of the mechanical energy (i.e., torque) required to twist the blade  138  due to the negative spring force experienced by the blade  138 . In practice, the apparatus  10  essentially “shuttles” energy between the blade  138  and biasing assembly  24 . When the blade  138  is in its twisted state, the blade is storing the energy that was previously stored in the apparatus  10 . When the actuator  148  returns the torque tube  90  to its initial position (i.e., to de-flex the blade  138 ), the energy in the blade  138  is transferred back to the apparatus  10 . The apparatus  10  thus provides substantially a “zero stiffness” at the root portion  140  of the blade  90  that allows the blade  138  to twist with only a very small force from the external actuator  148 . 
         [0064]    With further reference to  FIG. 1 , the apparatus  10  is assembled such that the biasing assemblies  24  are under compression (i.e., preloaded) when the torque tube  90  is in the position shown in  FIG. 3 . Thus, the linkage assemblies  30  will each have three points of equilibrium, one being represented by the position of the coupling assemblies  30  in  FIG. 3 , one by the position of the linkage assemblies in  FIG. 3 , and one where the torque tube  90  has been rotated slightly clockwise from the orientation shown in  FIG. 3 . The coupling assemblies  30  are thus free to move the torque tube  90  either clockwise or counterclockwise in the drawings of  FIGS. 1 and 3 , and the position of the linkage assembly  30  in  FIG. 1  represents rotation of the torque tube in the counterclockwise direction. Once the actuator  148  ( FIG. 2 ) applies a very small force to the torque tube  90 , the biasing force provided by the biasing assemblies  24  immediately assists in rotating the torque tube  90  either clockwise or counterclockwise depending upon the movement of the actuator  148 . With the linkage assemblies  30  in the position of equilibrium shown in  FIG. 3 , only a very small force is required from actuator  148  to hold the torque tube  90  stationary. However, as described above, rotation of the torque tube in either the clockwise or counterclockwise directions (relative to  FIGS. 1 and 3 ) requires only a very small force from the actuator  148 . In practice, the reduction of torque required by the actuator  148  can be up to an order of 1/1000 of the torque that would otherwise be required to twist the blade  138 . 
         [0065]    Referring now to  FIGS. 32-34 , the force required to move the torque rod  90  and the energy required to return the torque rod to its initial position of equilibrium will be described in connection with several formulas. The torque provided by each linkage assembly  30  to the torque tube  90  can be expressed by the following formula: 
         [0000]        T   SES-to-Ptt =2* L*F   spring *sin(Θ Ptt )   Equation 1 
         [0066]    Where: T SES-to-Ptt  is the torque applied to the torque tube  90 . 
         [0067]    The change in length of the biasing assembly (i.e., spring) can be represented by the following formula: 
         [0000]      δ X =2 *L (1−cos(Θ Ptt ))   Equation 2 
         [0068]    The force needed to move the biasing assemblies from one stable position to the other is represented by: 
         [0000]    
       
         
           
             
               
                 
                   
                     F 
                     min 
                   
                   = 
                   
                     
                       T 
                       
                         Ptt 
                         - 
                         max 
                       
                     
                     
                       2 
                       * 
                       L 
                       * 
                       
                         sin 
                          
                         
                           ( 
                           
                             Θ 
                             
                               Ptt 
                               - 
                               max 
                             
                           
                           ) 
                         
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   3 
                 
               
             
           
         
       
     
         [0069]    Referring to  FIG. 33 , graph  150  illustrates that the energy stored by the torque tube  90  is essentially equal to the energy provided by the baising assemblies  24 . 
         [0070]    Referring to  FIG. 34 , the energy required to return the torque tube  90  to its initial position of equilibrium (shown in  FIG. 3 ) is represented by portion  154  of graph  152 . 
         [0071]    From the foregoing, then, it will be appreciated that the apparatus  10  provides a means for dramatically reducing the force needed by an actuator to twist or bend an air foil, wing, rotorcraft blade or any other object that requires a bending or twisting force to be applied thereto during its operation. 
         [0072]    While various embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the inventive concept. The examples illustrate the disclosure and are not intended to limit it. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.