Abstract:
Disclosed herein is a cover for a rod end of an actuator. The cover comprises a mounting collar for surrounding and mounting to a portion of the rod end. The collar is deformable such that it may be mounted over a rod eye mounted to the rod end. The cover further comprises a shield extending from the collar and shaped such that when attached to the rod end the shield shields a portion of rod end to prevent fluid or foreign object ingress to the rod end. Also disclosed is a rod end assembly comprising a rod end and a cover mounted thereto and a method of assembling and retro-fitting a rod end and cover.

Description:
FOREIGN PRIORITY 
       [0001]    This application claims priority to Indian Patent Application No. 201641016478 filed 11 May 2016, the entire contents of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a cover for a rod end of a linear actuator. 
       BACKGROUND 
       [0003]    Aircraft systems typically contain a number of linear actuators such as hydraulic actuators. For example, hydraulic actuators may be used to operate doors for accessing components within an engine nacelle. These actuators are often moving large flexible panels and therefore are attached to the panels via a rod end that is spring loaded to the actuator piston rod. The spring loaded rod end acts as a lost motion device to accommodate flexure in the panels. 
         [0004]    Current rod end design includes a hollow cylindrical shaft for attachment to a piston rod and a rod eye for attachment to a clevis. The hollow shaft includes a slot or hole extending through a wall of the shaft to allow the rod end be mounted to the piston rod in such a way that the rod end may move axially relative to the piston rod under the spring loading. However, this slot provides a flow path for water to enter the internal cavity of the hollow shaft and accumulate in the rod end, piston rod or actuator. Water inside the system will swell as it freezes which may cause damage to the rod end, piston rod or actuator. 
         [0005]    It is therefore desired to minimise water ingress via the rod end. 
       SUMMARY 
       [0006]    Disclosed herein is a cover for a rod end of an actuator. The cover comprises a mounting collar for surrounding and mounting to a portion of the rod end. The collar is deformable such that it may be mounted over a rod eye mounted to the rod end. The cover further comprises a shield extending from the collar and shaped such that when attached to the rod end the shield shields a portion of rod end to prevent fluid or foreign object ingress to the rod end. 
         [0007]    Also disclosed herein is a rod end assembly comprising a rod end and a cover. The rod end comprises a hollow shaft and a rod eye mounted to an end of the shaft. The shaft end has an opening extending through a wall thereof. The cover is mounted to the rod end and comprises a mounting collar mounted to a mounting portion of the rod end. The collar is deformable such that it may be mounted to the rod end over the rod eye. The cover further comprises a shield extending from the collar and shielding the opening in the shaft wall to prevent fluid or foreign object ingress to the rod end. 
         [0008]    In an embodiment of any of the above, the shield is a skirt extending around the entire circumference of the mounting collar and projecting therefrom. The skirt may be a hollow cylindrical tube, for example. 
         [0009]    The collar may include at least one axial split to allow parts of the collar to move relative to one another, the at least one split extending along the whole axial length of the collar and shield. In an embodiment, the collar includes two diametrically opposed axial splits. 
         [0010]    In an alternative arrangement, the collar may comprise at least two splits circumferentially spaced from one another, wherein the at least two splits extend down the collar and only part of the length of the shield to define a deformable finger therebetween. For example, the collar and shield may comprise four of such splits arranged in two opposing pairs to form two opposing fingers of the cover. 
         [0011]    The cover may further comprise an alignment portion for positioning of the cover relative to rod eye. For example, the alignment portion may be a loop extending from one side of the collar to the opposite side of the collar on the opposite side of the collar to the shield or alternatively the alignment portion may comprise two diametrically opposed arms extending in an opposite axial direction to the shield. Parts of, or the entire, alignment portion may be configured to conform to an external surface of the rod eye for mounting thereto. 
         [0012]    The cover may further comprise one or more straps, bands or clips surrounding the collar or shield for securing the cover onto the rod end. The collar or shield may further include one or more circumferential grooves for housing the straps, bands or clips. 
         [0013]    A method of assembling a rod end and cover is also described herein. The method comprises providing a rod end comprising a hollow shaft and a rod eye mounted to an end of the shaft and the shaft end having an opening extending through a wall thereof, the rod end being attached to a piston rod. The method further comprises providing a cover as described above and mounting the cover to the rod end without removing the rod end from the piston rod by pushing the cover onto the rod end while deforming the collar of the cover. 
         [0014]    Deforming the cover may include prising the collar apart between two axial splits extending the whole length of the collar and shield. 
         [0015]    Deforming the cover may include deflecting fingers formed in the collar. In such an embodiment, the method may further comprise orienting the fingers such that they deflect over a widest part of the rod eye. The method may further comprise rotating the cover such that the fingers are circumferentially spaced from the opening in the rod end shaft. 
         [0016]    The above method may involve retro-fitting the cover to a rod end in an existing actuation system. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  shows an exploded view of a first cover and a rod end prior to assembly 
           [0018]      FIG. 2  shows a perspective view of the cover of  FIG. 1  mounted on the rod end 
           [0019]      FIG. 3  shows a perspective view of a second cover mounted to a rod end 
           [0020]      FIG. 4 a    shows an exploded view of a third cover and a rod end attached to a piston rod of an actuator prior to attachment of the cover 
           [0021]      FIG. 4 b    show the assembly of  FIG. 4 a    with the cover being assembled 
           [0022]      FIG. 4 c    shows the assembly of  FIG. 4 a    with the cover in its final position on the rod end 
           [0023]      FIG. 4 d    shows the assembly of  FIG. 4 c    with a strap for holding the cover in position 
           [0024]      FIG. 5  shows a cross sectional view of the cover and rod end of  FIGS. 1 and 2 , with the rod end attached to a clevis 
       
    
    
     DETAILED DESCRIPTION 
       [0025]      FIG. 1  shows a rod end  10  of the type typically attached to a piston rod of a hydraulic actuator (not shown). The rod end  10  has a hollow cylindrical shaft  12  for mounting to an end of a piston rod and a rod eye  14 . The rod eye  14  includes a cylindrical bore  13  for receiving a clevis pin  54  (as shown in  FIG. 5 ) such as those found in existing power door opening systems in aircraft, for example. The rod eye further includes protrusions  15  for engaging a complementary groove in the clevis. 
         [0026]    The rod end  10  also includes a flange  16  which acts as a stop for axial movement of the rod end  10  relative to the piston rod. The maximum diameter of the rod eye  14  is larger than the diameter of the flange  16  meaning that a device with sufficiently large diameter to fit over the eye  14  will be unable to effectively engage with the flange  16 . 
         [0027]    The rod end  10  further includes an axially extending slot  17  formed in the shaft  12 . The slot  17  extends through a wall of the shaft  12  to allow the rod end  10  to be pinned to a piston rod in such a way that it may move axially relative to the piston rod but not rotationally. The slot  17  therefore provides a flow path for water to enter the internal cavity of the hollow shaft  12  and from there into the piston rod. 
         [0028]      FIG. 1  also shows a first embodiment of a cover  70  for mounting to the rod end  10 . The cover  70  has a main body  20  which is shaped such that it surrounds an upper portion of the rod end  10 . The body  20  includes a mounting collar  21  for engagement with the flange  16  which acts as a mounting portion of the rod end  10 . The mounting collar  21  has an internal diameter approximately equal to the external diameter of the flange  16  for a tight fit therewith. 
         [0029]    The cover  70  further includes a cylindrical skirt  22  extending in a first axial direction from the mounting collar  21  and an alignment portion  24  extending in the opposite axial direction from the mounting collar  21 . 
         [0030]    As shown in  FIG. 2 , when mounted to the rod end  10 , the cylindrical skirt  22  of the cover  70  extends over a portion of the rod end shaft  12  and shields the slot  17  thereby obstructing the flow path for water entering the shaft  12  via the slot  17 . 
         [0031]    Although the described embodiment includes a cylindrical skirt  22 , it will be appreciated that other forms of shield may be provided in order to shield the radial opening or slot  17 . Although a cylindrical tube may be simple to form, for example on a lathe, alternatively the shield or skirt  22  could be moulded to any shape or size that shields the opening  17 . For example the skirt  22  might extend over the opening  17  but not extend completely around the rod end  10 . Such an embodiment may reduce the amount of material needed for the cover  70 . As shown in the embodiment, the skirt  22  may be configured to extend over a portion of the rod end  10  from the collar  21  to beyond the opening  17  i.e. completely cover the opening  17 . Such an arrangement may provide the most comprehensive protection. However, alternatively the skirt  22  could extend over a portion of the rod end  10  but stop over or before the opening  17 . In this arrangement the skirt  22  may deflect water away from the slots  17  without completely covering them. 
         [0032]    In this embodiment, the alignment means  24  is in the form of a loop extending from the skirt  22 . The loop is shaped such that it over-wraps the rod eye  14 , in other words the internal geometry of the loop matches the external geometry or outer diameter of the rod eye  14  and extends thereover. As shown in  FIG. 5 , the thickness of the loop  23  is such that the alignment means does not interfere with the rotation of the rod eye within the clevis  52  as illustrated in  FIG. 5 . The alignment means also conforms to the protrusions  15  in the rod eye  14 . 
         [0033]    The alignment means  24  thus helps position the cover  70  when mounting it to the rod end by preventing the cover  70  from moving further axially down the rod end  10  towards the piston rod. The alignment of the alignment means with the eye  14  also ensures the correct orientation to the cover  70  and may prevent rotational movement of the cover  70  about the axis of the shaft  12  when the clevis  52  and rod end  10  are assembled. 
         [0034]    The collar  21  and skirt  22  include two diametrically opposed, axially extending splits  30  extending along the axial length of the collar  21  and skirt  22 . The splits  30  are positioned on the skirt  22  such that when the cover  70  is mounted to the rod end  10 , the splits  30  are circumferentially spaced (i.e. not aligned) with the slot  17  of the rod end  10 . 
         [0035]    The cover  70  is made from a resilient or pliable material such as corrosion resistant steel or injection moulded polymer such that radial force applied to the inside surface of the skirt  22  causes the cover  70  to deform and the skirt  22  to open up and thereby fit over the rod eye  14  despite the internal surface of the cover body  20  and the skirt diameter being smaller that the widest part of the rod eye  14 . The cover  70  then regains its former shape once it has passed over the widest part of the rod eye  14 . The internal surface of the body  20  can thus engage with the flange  16  and the cover  70  can be mounted without having to remove the rod end  10  from the actuator assembly. In this way the cover  70  can be retro-fitted onto existing rod end and piston rod assemblies. 
         [0036]    The collar  21  is deformable such that different parts of the cover  70  can move relative to each other thereby allowing the cover  70  to be mounted to a rod end  10 . The skirt  22 , for example, may be deformable to allow it increase in diameter to fit over a rod eye  14 . The cover  70  may be configured such that it can be deformed in this way manually or with the use of a tool. The cover  70  may be made from resilient or flexible material. The cover  70  may be partially resilient or flexible i.e. parts of the cover  70  may be resilient or flexible and other parts of the cover  70  may be rigid. The cover  70  may include a resilient collar  21 , skirt  14  and/or a resilient alignment portion  24 , for example. 
         [0037]    The cover  70  further includes two axially spaced grooves  26  extending circumferentially around the skirt  22  at either axial end of the skirt  22 . The grooves  26  are sized and shaped to such that a strap, band or jubilee clip (not shown) can be used to secure the cover  70  against the stop flange  16  of the rod end  10 . 
         [0038]      FIG. 3  shows a second embodiment of the cover  70 . The cover  70  of  FIG. 3  is substantially as described above in relation to the first embodiment except that instead of having two splits  30  extending the whole length of the skirt  20 , the cover  70  includes four splits  30  all extending along only a portion of the length of the skirt  22 . The splits  30  of this embodiment extend all the way through the collar  21  and from the top of the skirt  22 , at an axial position at which the alignment means  24  is attached to the skirt  22 , to a point partway down the axial length of the skirt  22  spaced from the actuator end of the cover  70 . The four splits  30  are positioned in two diametrically opposed pairs. The splits  30  of each pair are circumferentially spaced from each other to define deformable fingers  32  therebetween. 
         [0039]    This embodiment also differs from that described above in that it includes only one circumferential groove  26 . The groove  26  is positioned at the top of the skirt  22  such that a strap, band or clip attached in the groove  26  secures the cover  70  to the flange  16  of the rod end  10  and prevents outward deflection of the fingers  32 . 
         [0040]      FIGS. 4 a  to 4 d    show a third embodiment of the cover  70  at various stages during its assembly on a rod end  10 .  FIGS. 4 a - d    show the rod end  10  attached to a piston rod of a hydraulic actuator. 
         [0041]    The cover  70  of  FIGS. 4 a -4 d    is substantially the same as that shown in  FIG. 3  with the exception that the alignment means instead includes two axially extending arms  25 . The arms  25  of this embodiment extend along outer diameter surface of the rod eye  14  such that the clevis  52  will prevent rotation of the arms  25  about the axis of the shaft  12 . The arms  25  are biased to deflect towards the rod eye  14  to grip thereon. 
         [0042]      FIG. 4 a    shows the cover  70  aligned with the rod end  10  ready for assembly thereto. The cover  70  is oriented such that the deformable fingers  32  are aligned with the widest part of the rod eye  14  so that when the cover  70  is pushed onto the rod end  10  (as shown in  FIG. 4 b   ) the fingers  32  can expand over the widest part of the rod end  10 . 
         [0043]    When the cover  70  is in an axial position whereby the skirt  22  is positioned over the slot in the rod end  10  the cover  70  is twisted about the rod end axis by about 90 degrees such that the arms  25  are aligned with the rod eye  14  and the splits  30  are oriented away from the slot in the rod end  10  as shown in  FIG. 4 c   . A strap  40  can then be attached within the grove  26 . 
         [0044]      FIG. 4 d    shows the cover  70  mounted to the rod end  10  with the strap  40  tightened thereto. 
         [0045]    Although the examples shown include a collar  21  in the form of an internal flange for mounting against the rod end flange  16 , it will be appreciated that any internal surface of the collar  21  that can be mounted or secured to the flange  16  of the rod end could be used. 
         [0046]    The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims