Abstract:
A hold open rod may include: an outer tube and an inner tube; a locking mechanism configured to selectively lock the inner tube with the outer tube; a locking groove in an outer surface of the inner tube; a locking dog and an outer housing covering the locking dog and at least part of the locking mechanism, the outer housing defining a cavity to contain the locking dog when the locking dog is in the outer radial position and also having an angled inner wall configured to engage the locking dog to move the locking dog to the inner radial position when the outer housing is moved to a locking position. A method of actuating a locking rod may be provided.

Description:
FIELD OF THE INVENTION 
     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 on a hold open rod. 
     BACKGROUND OF THE INVENTION 
     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 being opened manually or automatically. Hold open rods may support a considerable amount of weight, particularly in the aviation industry. It is desired that the rods function correctly and do not malfunction in supporting the doors or hatches. 
     Generally hold open rods include two cylindrical telescoping tubes, a first tube disposed inside a second, tube. In the resting 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 a door. At the extended position, the tubes are locked in place, holding open the door. Such locking prevents the inner tube from retracting into the outer tube and also subjects the tubes to the weight of the door. The locking mechanism can be released by an operator. 
     The locking mechanism holding the rods in the extended position can deteriorate or wear over time. Further, some prior art designs may appear to be worn from normal use. It is desirable to provide an improved locking mechanism that functions over long periods of time, holds larger loads reduces the appearance of wear and is durable. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein in one aspect an apparatus is provided that in some embodiments provides a locking mechanism for hold open rods that functions over long periods of time, holds large loads reduces the appearance of wear and is durable. 
     In accordance with one embodiment of the present invention, a lockable hold open rod may be provided. The hold open rod may include: an outer tube and an inner tube, the inner tube configured to slide in and out of the outer tube; a locking mechanism configured to selectively lock the inner tube with the outer tube; a locking groove in an outer surface of the inner tube; a locking dog configured to slide along the outer surface of the inner tube when the locking dog is in an outer radial position and fit in the locking groove when the locking dog in an inner radial position; and an outer housing covering the locking dog and at least part of the locking mechanism, the outer housing defining a cavity to contain the locking dog when the locking dog is in the outer radial position and also having an angled inner wall configured to engage the locking dog to move the locking dog to the inner radial position when the outer housing is moved to a locking position. 
     In accordance with another embodiment of the present invention, a method of actuating a locking rod may be provided. The method may include: moving a lock collar axially along an outer tube; sliding an inner tube with respect to an outer tube to align a locking groove with a locking dog; and moving the locking dog radially inward into the locking groove by sliding a surface on the lock collar against a surface on the locking dog wherein the locking dog is a reinforced plastic material. 
     In accordance with yet another embodiment of the present invention, a lockable hold open rod may be provided. The hold open rod may include: an outer tube and an inner tube, the inner tube configured to slide in and out of the outer tube; a locking mechanism configured to selectively lock the inner tube with the outer tube; a locking groove in an outer surface of the inner tube; a means for radially engaging configured to slide along the outer surface of the inner tube when the means for radially engaging is in an outer radial position and fit in the locking groove when the means for radially engaging is in an inner radial position; and an outer housing covering the means for radially engaging and at least part of the locking mechanism, the outer housing defining a cavity to contain the means for radially engaging when the means for radially engaging is in the outer radial position and also having an angled inner wall configured to engage the means for radically engaging to move the means for radially engaging to the inner radial position when the outer housing is moved to a locking position. 
     There has 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. 
     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. 
     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 
         FIG. 1  is a perspective view of a hold open rod system in a retracted position. 
         FIG. 2  is a perspective view of the hold open rod system of  FIG. 1  in an extended position. 
         FIG. 3  is a cross-sectional view of a locking mechanism of the hold open rod system of  FIG. 1  in the retracted position. 
         FIG. 4  is a cross-sectional view of the locking mechanism of  FIG. 3  in the extended position. 
         FIG. 5  illustrates another embodiment of a feature of the locking mechanism of  FIG. 1 . 
         FIG. 6  illustrates yet another embodiment of a feature of the locking mechanism of  FIG. 1 . 
         FIG. 7  illustrates still another embodiment of a feature of the locking mechanism of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     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 an apparatus is provided that in some embodiments provides a locking mechanism for hold open rods that functions over long periods of time, holds large loads and is durable. 
     An embodiment of the present inventive apparatus is illustrated in  FIG. 1 .  FIG. 1  is a perspective view of a hold open rod system  10 . The hold open rod system  10  includes an inner  12  and outer  14  tube and a locking mechanism  16 . Fasteners  15 , are connected to the inner  12  and outer  14  tubes. In this view, the system  10  is shown in a retracted, resting position. 
       FIG. 2  is a perspective view of the hold open rod system  10  of  FIG. 1 . In this view, an inner tube  12  is shown extending out from an outer tube  14 . Fasteners  15  are connected to the inner tube  12  and the outer tube  14 . The fasteners  15  permit the hold open rod system  10  to attach doors or hatches of an aircraft which are to be held open. The fasteners  15  may be threaded, press fit or otherwise attached to the inner  12  and outer rods  14 . Fasteners  15  are connected to the inner tube  12  and the outer tube  14 . A locking mechanism  16  is shown in an a locking state, as will be described herein. 
       FIG. 3  is a cross-sectional view of the locking mechanism  16  in a retracted, unlocked position. In this position, the inner tube  12  is disposed circumferentially within an outer tube  14 . The locking mechanism  16  includes a release collar  40  having an outer housing  17 , and locking dogs  18  disposed around the inner tube  12 . The dogs  18  may be disposed circumferentially around the inner tube  12  contacting an outside wall  20  of the inner tube  12 . As in the embodiment shown there may be two locking dogs  18  that are located opposite to each other. The locking dogs  18  can have a variety of geometries as will be discussed further. 
     As shown in  FIGS. 3 and 4 , dogs  18  have a sloped surface  19  in that corresponds with a sloped surface  21  on the outer housing  17 . The sloped surface  19  on the dogs  18  and the sloped surface  21  on the outer housing  17  interact to compress the locking dogs  18  which will be discussed further later below. 
     A lock body  22  surrounds the inner and outer tubes  12 ,  14  respectively. Specifically, the lock body  22  is a tubular structure that has a first end  24  and a second end  26 . The first end  24  and second end  26  have varying diameters, such that the second end  26  has a larger diameter than the first end  24 . In some embodiments the second end  26  may have internal threads that permit the inner tube  12  to threadably attach to the release collar  40 . 
     Proceeding longitudinally from the first end  24  to the second end  26 , the locking body  22  has a tubular shape. There is at least one larger diameter opening  28  for placement of the locking dogs in the lock body  22 . In the cross-sectional illustration depicted in  FIG. 3 , there are least two such openings  28 . Thereafter, the lock body  22  geometry flares outwardly towards the second end  26 . This flare is characterized by inner seat  30  formed on an inside surface  32  of the lock body  22  and an outer seat  34  formed on an outer surface  36  of the lock body  22 . 
     Proceeding further toward the second end  26 , the lock body has a depression  38  and a lip  39  defined by the depression  38  and the second end  26  for connecting with the outer tube  14 . In some embodiments the connection may be via threads. The geometry of the lock body  22  may have a smaller diameter adjacent the first end  24  to accommodate the diameter of just the inner tube that it retains at the first end  24  and a larger diameter adjacent the second end  26  to accommodate the diameters of both the inner tube  12  and the outer tube  14  that it retains at the second end  26 . 
     The lock body  22  and the locking dogs  18  are themselves circumferentially contained within a release collar  40 . The release collar  40  generally tubular in shape, has a first end  42  and a second end  44  remote therefrom. Adjacent the first end  42  of the release collar  40  is a release collar cavity  46  for providing a space for locking dogs  18  when the locking dogs  18  are not in a locking position. The release collar cavity  46  has a first portion  48  disposed toward the first end  42  and a second portion  50 . Further, the cavity  46  includes the sloped surface  21  that allows the locking dogs  18  to be fed into the second portion  50 . The first portion  48  has a larger diameter and geometry than the second portion  50 , such that the first portion  48  of the cavity  46  can accommodate the size and shape of the locking dogs  18  when the locking system  10  is in a relaxed, unlocked and retracted state. The second portion  50  of the release collar cavity  46  has a smaller diameter so as to capture and retain the locking dogs  18  when the inner and outer tubes,  12 ,  14 , respectively, are placed in an extended, locked position as shown in  FIG. 4 . 
     The release collar  40  further includes a lip  54  for preventing the locking dogs  18  from sliding down the outer wall  20  of the inner tube  12 . A spring  56  is positioned inside the release collar  40  to surround the lock body  22 . In particular, the spring  56  is retained inside the release collar  40  by the outer seat  34  of the locking collar  22 . The spring  56  retracts and contracts as the locking mechanism  16  is locked and unlocked. 
       FIG. 4  is a depiction of the locking mechanism  16  in an extended, locked position. In  FIG. 3 , a first end  58  of the inner tube  12  was visible and positioned adjacent the locking mechanism  16 . However, in  FIG. 4 , illustrating the extended, locked position, a second end  60  of the inner tube  12  is visible. The second end  60  of the inner tube  12  includes at least one inner tube groove  62  having a geometry to accommodate the locking dogs  18 . The inner tube groove  62  is formed on an outer wall  20  of the inner tube  12 . The groove  62  is dimensioned such that the locking dogs  18  will fit between the groove  62  and the second portion  50  of the release collar  40 . The groove  62  is formed at a location near the second end  60  so that when the locking mechanism  16  is in the extended locked position, the inner and outer tubes  12 ,  14  respectively, can have the longest length possible. 
     The second end  60  also includes a circumferential protrusion or stop  64 . The stop  64  catches against the inner seat  30  of the locking body  22  and prevents the inner tube  12  from sliding all the way through the lock body  12 . The stop  64  may be formed integrally with the inner tube  12  or be formed separately and attached to the second end of the  60  of the inner tube  12 . 
     In operation, during the relaxed, retracted and unlocked position, the locking dogs  18  are circumferentially spaced about the outer wall  20  of the inner tube  12  and are located adjacent the first portion  48  of the release collar  40  as shown in  FIG. 3 . An example of when the hold open rod system  10  is in this unlocked position is when a door held open by the hold open rod system  10  is in a closed position. To extend and lock the hold open rod system in place, the inner tube  12  is extended out from the outer tube  14 . As the inner tube  12  is extended out, the locking dogs  18  ride on the outer wall  20  of the inner tube  12  until they approach the groove  62  of the inner tube  12 . Then, the locking dogs  18  are angled radially inward by the angled surface  21  such that the locking dogs  18  fall into the groove  62  and are held in place by the second portion  50  of the release collar  40 . The locking dogs  18  stay thusly situated until an operator releases the locking mechanism. 
     To release the locking dogs  18 , an operator slides the release collar  40  and compresses the spring  56  such that the locking dogs  18  are angled upward and outward, radially by the wall  21 , allowing the locking dogs  18  to return to the first portion  48  of the release collar cavity  46 . The release collar  40  can be configured such that the locking dogs  18  are released with a pull or slide motion or a turn-and-pull (or slide) motion. Then the locking dogs  18  slide on the outer wall  20  of the inner tube  12  as the inner tube  12  is retracted back into the outer tube  14 . 
       FIGS. 5-7  provide depictions of alternate embodiments of locking dogs  18 . In particular,  FIG. 5  shows a perspective view of a locking dog  18  having a generally elongated block like structure with rounded ends.  FIG. 6  illustrates yet another embodiment of a locking dog  18 . This embodiment has a shape similar to a torridal section (a section of a torus) with champhered ends.  FIG. 7  illustrates a generally spherical structure. In the embodiments shown in  FIG. 5 , the locking dog  18  has sloped surface  19  for sliding along the sloped surface  17  on the outer housing  21  as discussed above. The embodiments shown in  FIGS. 6 and 7  have general curved surfaces  66 . The general curved surfaces  66  perform the function of sliding along the sloped surface  21  of the outer housing  17 . The arched sections  68  as shown in  FIGS. 5 and 6  allow the dogs  18  to engage the ached groove  62 . Thus the locking dogs  18  can have a variety of geometries and are within the scope of the present invention. 
     Further, in a preferred embodiment of the present invention, the locking dogs  18  are formed of a reinforced plastic material, such as but not limited to, glass or carbon reinforced materials including Polyamide-imide (PAI), such as Torlon™ polymer available from Solvay Plastics. This material is a strong material that can withstand the large loads that the locking mechanism  10  will be subjected to but will not cause wear on the outer wall  20  of the inner tube  12 . 
     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.