Abstract:
A hold open rod is provided. The hold open rod may include: an outer tube; an inner tube having two ends, at least one end configured to slide within the outer tube; a tube stop located at one end of the inner tube; a groove around the circumference of the tube stop; and a resilient material located in the groove, the resilient material contacting the tube stop and the outer tube. A method of reducing wear on a hold open rod may be provided. The method may include: locating first resilient material between an inner tube and an outer tube; providing a locking mechanism to lock the inner tube with respect to the outer tube; and providing a second resilient material between an isolator and a collar on the locking mechanism.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to hold open rods. More particularly, the present invention relates to an apparatus and method for locking a hold open apparatus. 
       BACKGROUND OF THE INVENTION 
       [0002]    Hold open rods are well known in the both the automotive industry and the aviation industry. Hold open rods hold open a door or hatch after the door or hatch has been opened manually or automatically. Hold open rods may support a considerable amount of weight. It is desired that the rods function correctly and do not malfunction in supporting this weight. 
         [0003]    Generally, the rods include two cylindrical, telescoping tubes, a first tube disposed inside a second tube, this constitutes an inner and outer tube, respectively. When in the resting or “stowed” position, the inner tube is generally located almost entirely within the outer tube. The inner tube can be extended to a designated position to hold open the door. At this extended position, the tubes are locked in place, in order to open the door. Such locking prevents the inner tube from retracting into the outer tube and also permits the tubes to support the weight of the door. The locking mechanism can be released by an operator. 
         [0004]    In aerospace applications hold open rods are often subject into intense vibration during flight. Due to the interaction between the inner tube and the outer tube, unwanted noise and fretting occurs between contacting parts. This fretting can cause premature wear to the hold open assembly. Further, the fretting may potentially damage or eliminate the corrosion protection coating applied to components of the hold open rod and thereby potentially compromise the ability of the hold open rod to be resistant to corrosion. Removing corrosion resistant coatings may potentially impair the functionality of the hold open rod. 
         [0005]    Thus it would be desirable for a method or system that can dampen or eliminate noise and fretting between hold open rod components. Particularly, dampening is desired in hold open rods used in the aviation industry. In the aviation industry, a door or hatch is likely to be maintained in the closed position where vibration may be experienced between the various components of the hold open rod, and where significant fretting has long been known to occur. Further, it may be desirable for the dampening system to reduce noise and/or wear due to vibration of the hold open rod. 
       SUMMARY OF THE INVENTION 
       [0006]    The foregoing needs are met, to a great extent, by the present invention. In one aspect, a system or method is provided that may dampen and/or eliminate noise and fretting between hold open rod components. In particular, the system may be effective when a hold open rod is in a closed position where the vibration most often is experienced and where significant fretting between components has long been known to occur. 
         [0007]    In accordance with one embodiment of the present invention, a hold open rod is provided. The hold open rod may include: an outer tube; an inner tube having two ends, at least one end configured to slide within the outer tube; a tube stop located at one end of the inner tube; a groove around the circumference of the tube stop; and a resilient material located in the groove, with the resilient material configured to contact the tube stop and the outer tube. 
         [0008]    In accordance with another embodiment of the present invention, a hold open rod may be provided. The hold open rod may include: an outer tube; an inner tube having two ends, at least one end configured to slide within the outer tube; means for locking configured to be actuated to selectively release and lock the inner tube with the outer tube; an isolator contained by the releasing means surrounding the outer tube; and means for reducing wear surrounding and contacting the isolator and the releasing means. 
         [0009]    In accordance with yet another embodiment of the present invention, a method of reducing wear on a hold open rod may be provided. The method may include: locating first resilient material between an inner tube and an outer tube; providing a locking mechanism to lock the inner tube with respect to the outer tube; and providing a second resilient material between an isolator and a collar on the locking mechanism. 
         [0010]    There have thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below, and which will form the subject matter of the claims appended hereto. 
         [0011]    In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting. 
         [0012]    As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of a hold open rod in accordance with an embodiment of the invention. 
           [0014]      FIG. 2  is a cross-sectional view of a portion of a hold open rod in accordance with an embodiment of the invention. 
           [0015]      FIG. 3  is a cross-sectional view of a portion of the hold open rod in accordance with an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a method and apparatus for dampening the vibration within a hold open rod. The dampening may reduce fretting, wear, and/or noise within the hold open rod as it is subjected to vibration incidental to travel such as air travel. 
         [0017]      FIG. 1  illustrates a hold open rod  10  in accordance of an embodiment of the invention. The hold open rod  10  includes an inner tube  12  that slides within an outer tube  14 . The position of the hold open rod  10  shown in  FIG. 1  is the stowed, also referred to as the rest, or retracted position. In this position, the inner tube  12  is substantially inside the outer tube  14 . 
         [0018]    The hold open rod  10  may be extended by sliding the inner tube  12  far enough out from the outer tube  14  to reach a desired length. The hold open rod  10  includes fasteners  16  to connect the hold open rod  10  to an object to which it will be mounted. For example, fasteners  16  may attach to a door or hatch on one side and on the other side to a frame of the door or hatch, thereby allowing the hold open rod  10  to hold the door or hatch in an open position. The hold open rod  10  can be allowed to selectively lock the inner tube  12  to the outer tube  14  in order to, for example, hold a door or hatch in an open position. The locking of the hold open rod  10  may be accomplished by manipulation of a collar  18 . 
         [0019]    When a hold open rod  10  is in a stowed position, as shown in  FIG. 1 , the door or hatch may likewise be in a closed position. Often, the stowed position is the position in which the hold open rod  10  spends a majority of its time. Vibration incidental with air travel can cause the hold open rod  10 , while in a stowed position, to wear, fret, rattle and make noise. 
         [0020]      FIGS. 2 and 3  illustrate an improved hold open rod  10  that may reduce wear, fretting and generation of noise.  FIG. 2  illustrates a cross-sectional partial view of a hold open rod  10  in accordance with an embodiment of the invention. The hold open rod  10  includes an end cap  20  placed at the end of an outer tube  14 . The end cap  20  may be secured to the outer tube  14  by a dowel or pin  32 , as shown. The dowel or pin  32  may extend from the end cap  20  into the outer tube  14  to secure the end cap  20  to the outer tube  14 . 
         [0021]    The inner tube  12  slides within the outer tube  14 . The inner tube  12  may be equipped with a stop  22 . The stop  22  helps prevent the hold open rod  10  from extending to the point that the inner tube  12  comes out of the outer tube  14 . The stop  22  may be attached to the inner tube  12  in any of a variety of ways. For example, as shown, a dowel or pin  30  may be used to connect the stop  22  to the inner tube  12 . In other embodiments of the invention, the stop  22  may be press fit, threadably fastened to the inner tube  12 , attached by an adhesive, other mechanical fasteners or any other suitable method. The stop  22  may include a flange  24 . The flange  24  may be of a slightly larger diameter than the inner tube  12  and may assist in preventing the hold open rod  10  from overextending by interference with a structured feature at the end of the outer tube  14  when the inner tube  12  is extended from the outer tube  14 . 
         [0022]    The flange  22  may include an O-ring grove  28  which seats an O-ring  26 . The O-ring  26  may be made of a resilient material such as, for example, rubber or another resilient material. The O-ring  26  provides a connection between the stop  22  and an inner diameter of the outer tube  14 . The O-ring  26  may help center the inner tube  12  within the outer tube  14 . The O-ring&#39;s resilience can help reduce a tendency to create noise, fretting or wear between the stop  22  or inner tube  12  and the outer tube  14 . 
         [0023]    While the stop  22  is located at the end  36  of the inner tube  12 , it may be desired to have one or more additional O-rings  40  (shown in phantom lines) situated along the length of the inner tube  12 . Such, additional O-ring grooves  38 , may be optionally present in the inner tube  12 . In concert with this, one or more fitted in optional O-rings  40  may be placed within the optional O-ring grooves  38 . The O-rings  26  and  40  may be selected so that the diameter of the O-rings  26  and  40  as installed is small enough to permit the inner tube  12  to slide within the outer tube  14 , but large enough that the actual structure of the inner tube  12  cannot contact the outer tube  14 . 
         [0024]      FIG. 3  illustrates a lock mechanism  34  which locks the inner tube  12  with the outer tube  14 . While the lock mechanism  34  is described in some detail it will be understood by one of ordinary skill in the art that various embodiments of the invention can use various lock mechanisms  34 . The lock mechanism  34  shown is meant to be an exemplary lock mechanism and does not limit the invention in anyway. Furthermore, it should be noted that in some embodiments the lock mechanism  34  is not an essential part of the invention but is merely an incidental feature of hold open rod  10 . 
         [0025]    As shown in  FIG. 3 , the hold open rod  10  includes an outer tube  14 . The outer tube  14  may be swaged. Other embodiments may include a lock body which is threaded into the outer tube  14  for performing the locking function. On the outer diameter of the swaged portion of the outer tube  14  on the locking mechanism  34 , there is a spring loaded collar  18 . The collar  18  houses locking dogs  42  and retains the locking dogs  42  radially against the outside diameter of the inner tube  12  while the rod  10  is in the retracted or stowed position. 
         [0026]    The locking dog  42  includes chamfered edges  44  and  46 . The locking slot  48  also includes chamfered edges  50  and  52 . The chamfered edges  44 ,  46 ,  50  and  52  aid in assisting the locking dog  42  moving in and out of the locking slot  48 . 
         [0027]    As shown in  FIG. 3 , the release collar  18  is in a position that prevents the locking dog  42  from exiting the locking slot  48 . Thus, the inner tube  12  and outer tube  14  are locked together. However, if the release collar is moved toward the right with respect to the orientation shown in  FIG. 3 , the opening  56  in the release collar  18  will be exposed to the locking dog  42  allowing the locking dog  42  to move out radially and into the opening  56 . Such a move by the locking dog  42  will unlock the inner tube  12  from the outer tube  14 . Some embodiments may require the release collar  18  to be twisted to unlock the hold open rod  10 . 
         [0028]    Movement of the release collar  18  to the right will cause the isolator  60  to move on the roller or ball bearing  62  located in the ball bearing slot  64  in the isolator  60 . The isolator  60  and ball bearing  62  may move within the ball bearing slot  66  in the outer tube  14  against the urging of the spring  68 . The spring  68  is between the isolator  60  and the spring stop  70  and exerts as a force on both. The spring stop  70  is placed against the thicker part  72  of the outer tube  14 . The user may overcome the force of the spring  68  by manually moving the release collar  18  towards the right, thereby unlocking the hold open rod  10  by exposing the opening  56  in the release collar  18  to the locking dogs  42 . Exposing the opening  56  allows the locking dogs  42  to move radially out of the locking slot  48  and into the opening  56 . Furthermore, movement of the release collar  18  back toward the left causes the locking dog  42  to slide its chamfered edge  44  along the chamfered side  58  of the opening  56  causing the locking dog  42  to move back into the locking slot  48 . 
         [0029]    The isolator  60  may include an O-ring groove  28  which contains an O-ring  26 . The O-ring  26  in the O-ring groove  28  may be resilient and perform similar function as the O-ring  26  as shown and described with respect to  FIG. 2 . The O-ring  26  helps to center the isolator  60  and the outer tube  14  within the collar  18 . The O-ring  26  may also help avoid the outer tube  14  from making noise with, fretting, wearing or otherwise rubbing against the release collar  18 . 
         [0030]    The isolator  60  may be made with plastic material and may include the ball bearing slot  64  for the ball bearing  62 . The number of ball bearings  62  used may vary depending on the size and the geometry of the hold open rods  10 . The O-ring  28  presses against the inner diameter of the collar  18  and the outer O-ring diameter of  28  of the isolator  60 . The ball bearing slot  64  of the isolator  60  then rests on the ball bearings  62  which are located on the outer diameter of the inner tube  12 . The ball bearings  62  allow the isolator  60  to move with reduced friction with the release collar  18  as the release collar  18  is pulled and/or turned to release the locking mechanism  34 . The isolator  60  and O-ring  26  provide dampening in order to reduce or eliminate contact between the release collar  18  and the outer tube  14  during vibration, thereby preserving any corrosion resistant coatings, other finishes, reducing noise, fretting and/or wear. 
         [0031]    In other embodiments of the invention, other locking mechanisms may be used, however in many of these embodiments resilient materials such as O-rings  26  may be used to prevent or reduce making noise, fretting, wear, or the removal of coatings or finish between parts due to rubbing of parts together during vibration. 
         [0032]    The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.