Abstract:
A hold open rod may include: an inner member; an outer member configured to have the inner member slide in and out of the outer member; a locking mechanism including a portion attached to the outer member and a portion attached to the inner member; a locking plug configured to move axially along an axis of the inner, outer members; a locking dog configured to move radially between a locking position and an unlocking position and a release cable operatively connected to the locking plug and configured to move the locking plug to the unlocking position. A method of actuating a lock mechanism on a hold open rod may also 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 and releasing the lock mechanism of 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. They support a considerable amount of weight, particularly in the aviation industry. It is desirable that the rods function correctly and do not malfunction in supporting this weight. 
     Generally the rods include two cylindrical telescoping tubes, a first tube disposed inside a second tube, an inner and outer tube, respectively. 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 the door or hatch. At this extended position, the tubes are locked in place, holding open the door for a period of time. Such locking prevents the inner tube from retracting into the outer tube and also permits the tubes to withstand the weight of the door or hatch. The locking mechanism can only be released by an operator. 
     It has been known that the locking mechanism holding the rods in the extended position can deteriorate over time. Further, in some applications, the locking mechanism that is positioned to ride along the exterior wall of the inner tube, causes grooves or indentations to be formed on the exterior wall which can be unsightly. Accordingly, it is desirable to provide an improved locking mechanism that functions over long periods of time, holds large loads and does not cause unsightly grooves on the rods. 
     SUMMARY OF THE INVENTION 
     The foregoing needs are met, to a great extent, by the present invention, wherein a hold open rod system is provided that, in some embodiments, functions over long periods of time, holds large loads and does not cause unsightly grooves on the rods. 
     In accordance with one embodiment of the present invention, a hold open rod may be provided. The hold open rod may include: an inner member; an outer member configured to have the inner member slide in and out of the outer member; a locking mechanism including a portion attached to the outer member and a portion attached to the inner member wherein the two portions are selectively locked to each other thereby locking the inner and outer members with respect to each other; a locking body configured to move axially along an axis of the inner, outer members and the locking mechanism to a locking and unlocking position; a locking dog configured to move radially between a locking position and an unlocking position as a result of a camming action with the locking plug as the locking plug moves axially; and a release cable operatively connected to the locking plug and configured to move the locking plug to the unlocking position when the cable is placed in tension, wherein the release cable extends outside the hold open rod. 
     In accordance with another embodiment of the present invention, a method of actuating a lock mechanism on a hold open rod may also be provided. The method may include: pulling on a cable and thereby: compressing a spring; moving a locking plug along an axis of the hold open rod; camming a locking dog along a slanted surface of the locking plug; moving the locking dog radially inward toward the axis; and moving the locking dog out of a locking slot. 
     In accordance with yet another embodiment of the present invention, a hold open rod may be provided. The hold open rod may include: an inner member; an outer member configured to have the inner member slide in and out of the outer member; a means for locking the inner member to the outer member; and a release cable operatively connected to the means for locking and configured to move the means for locking an unlocking position when the cable is placed in tension by moving a locking dog in the means for locking out of a locking slot by sliding the locking dog along a camming surface, wherein the release cable extends outside the hold open rod. 
     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 illustrating a hold open rod according to an embodiment of the invention. 
         FIG. 2  is a perspective view of a hold open rod according to an embodiment of the invention where the locking mechanism has been exposed. 
         FIG. 3  is a cross-sectional view of the locking mechanism and the hold open rod where the locking mechanism is in a locking position. 
         FIG. 4  is a cross-sectional view of the locking mechanism where the hold open rod or the locking mechanism is in an unlocked position. 
         FIG. 5  is a cross-sectional view of the hold open rod. 
     
    
    
     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 a hold open rod with a pull release system for unlocking the hold open rod. 
     An embodiment of the present inventive apparatus is illustrated in  FIGS. 1 and 2 . A hold open rod system  10  is shown in  FIGS. 1 and 2 . The system  10  includes an inner tube  12  and an outer tube  14 . The outer tube  14  surrounds the inner tube  12 . Both ends of the hold open rod system  10  include a fastener  16  for coupling the system  10  to a particular application, for example, an aircraft door or door frame (not shown). 
     The inner tube  12  is capable of sliding into the outer tube  14  to shorten the length of the hold open rod system such as when a door or hatch is shut. Then when the door or hatch is open, the inner tube  12  slides out of the outer tube  14 . To lock the inner tube  12  with respect to the outer tube  14 , a locking mechanism  18  provided. 
     In  FIG. 2 , the locking mechanism  18  is exposed. The outer wall  24  has been removed to reveal the locking body  19  and the locking dogs  48 . The locking mechanism will be described in more detail with respect to  FIGS. 3 and 4 . 
       FIG. 3  is a cross-sectional view of the locking mechanism  18  showing how the inner tube  12  and outer tube  14  attach to the locking mechanism  18 . The locking mechanism  18  shown in  FIG. 3  is shown in a locked position. This is in contrast to  FIG. 4 , which shows a cross-sectional view of the locking mechanism  18  in a unlocked position. As shown in  FIG. 3  a first end  20  of the outer tube  14  is attached to an outer housing  21  of the locking mechanism  18 . The locking mechanism  18  may be made of metal such as aluminum, steel or any other suitable substance. The inner  12  and outer tubes  14  may also be made of metal such as aluminum or steel or, in other embodiments of the invention, may be made of composite materials such as carbon fiber or any other suitable substances. 
     The outer tube  14  may attach to the outer housing  21  of the locking mechanism  18  via threads, press fit, fasteners, an epoxy or other adhesive, or any other suitable substance. 
     The outer housing  21  or locking mechanism  18  has an inner wall  22  and an outer wall  24 . The outer wall  24  of the outer housing  21  is exposed to outside environment whereas the inner wall  22  is exposed to internal components of the locking mechanism  18 . The outer tube  14  attaches to the outer housing  21  of the locking mechanism  18  at a second end  28  of the outer housing  21  of the locking mechanism  18 . The first end  26  of the outer housing  21  of the locking mechanism  18  does not attach to the inner tube  12 , rather the first end  26  of the outer housing  21  of the locking mechanism  18  does not butt against any structure but is exposed to the outside environment. The second end  28  of the outer housing  21  has a reduced diameter portion  30  which assists in attaching the outer housing  21  to the first end  20  of the outer tube  14 . The reduced diameter portion  30  fits inside a end wall portion  20  of the outer tube  14  and may be attached to the outer tube  14  in any number of ways. For example, the reduced diameter portion may be attached to the outer tube  14  by threads, a press fit, fasteners, an adhesive or any other suitable means. In the embodiment shown in  FIG. 3 , the outer housing  21  attaches to the outer tube  14  by projections  31  in the outer tube  14  fit into a groove  35  in the outer housing  21  of the locking mechanism  18 . 
     The inner wall  22  of the outer housing  21  is equipped with a locking groove  32 . The locking groove  32  has an angled portion  33  which may act as a camming surface for moving the locking dogs  48 . When the locking dogs  48  are in the locking groove  32 , the locking dogs  48  are in the locking position. The locking mechanism  18  also includes a locking plug  34  as shown in  FIG. 3 . The locking plug  34  secures the locking dogs  48  into the locking groove  32  when the locking plug  34  is in a locking position. 
     An end  36  of the inner tube  12  attaches to a first end  38  of the locking body  19  similar to the way the first end  20  of the outer tube  14  attaches to the second end  28  of the outer housing  21  of the locking mechanism  18 . The second end  36  of the inner tube  12  may attach to the first end  38  of the locking body  19  via threads, fasteners, an adhesive, a press fit or any other suitable means of attachment. 
     As shown in  FIG. 3 , a projection  39  fits into a groove  41  in the locking body  19 . In some embodiments of the invention, the inner tube  12  may be made of metal, such as aluminum or steel, or of a composite material such as, for example, but not limited to, carbon fiber. The locking body  19  may be made of metal such as aluminum or steel or any other suitable metal or material. 
     A stop  42  is attached to the second end  40  of the locking body  19 . The stop  42  provides a surface for a spring  62  to urge against. The spring  62  urges against the locking plug  34  at one end and the stop  42  at the other end. The stop  42  may be attached to the second end  40  of the locking body  19  via threads, a press fit, an adhesive or any other suitable means for attaching a stop  42  to the second end  40  of the locking body  19 . The stop  42  includes an open end  52  into which the spring  62  extends, and a closed end  54 . The closed end  54  provides the surface for the spring  62  to urge against. An opening  56  in a closed end  54  provides a pathway for the shaft  44  of the hook  64  to pass through the stop  42 . The stop  42  also includes a flange  58  which may provide a surface for the second end  40  of the locking body  19  to butt against. 
     The spring  62  biases the locking plug  34  to a position in the direction of the inner tube  12 , as shown in  FIG. 3 . The angled wall  70  of the locking plug  34  butts against the stop surface  60  of the locking body  19 . The stop surface  60  prevents the locking plug  34  from extending any further toward the inner tube  12 . The hook  64  is attached to the locking plug  34  via threads  65  on part of the shaft  44  and a threaded hole  67  in the locking plug  34 . The hook  64  could be attached to the locking plug  34  in any manner of ways such as press fit, welding, an epoxy, fasteners or any other suitable way of fasting the hook  64  to the locking body  34 . 
     Because the spring  62  biases the locking body  34  to the left as shown in  FIG. 3 , the hook  64  is also biased or moved to the left  64  by the spring  62 . When the locking plug  34  is moved to the left towards the inner tube  12  as shown in  FIG. 3 , the locking dogs  48  are forced into the locking groove  32 . The locking dogs  48  cause the outer tube  14  to be fixed or locked with respect to the inner tube  12 . When the locking plug  34  is in the locking position as shown in  FIG. 3 , the first end  66  of the locking plug  34  extends through the first end  38  of the locking body as shown in  FIG. 3 . 
     In order for the locking mechanism  18  to be in the locking position as shown in  FIG. 3 , tension on the cable  74  attached to the hook  64  must be slack or at least not significant enough to overcome the force of the spring  62 . When the tensile force in the cable  74  is greater than this force of the spring  62 , then the spring  62  will compress and the locking mechanism  18  will move to an unlocking position as shown in  FIG. 4 . 
     In  FIG. 4 , the cable  74  has moved the hook  64  to the right, or in other words, towards the outer tube  14 . Because the hook  64  and the locking plug  34  are connected to each other, the locking plug  34  is also moved to the right. The spring  62  has become compressed between the locking plug  34  and the stop  40 . Because the locking plug  34  has moved to the right, the first end  66  of the locking plug  34  could also move to the right and out of the first end  38  of the locking body  19 . The reduced diameter of the first end  66  of the locking plug  34  has permitted the locking dogs  48  to move radially inward. The angled wall  70  of the locking plug  34  has provided a camming surface for the angled portion  72  of locking dogs  48  to move radially inwardly along. This movement caused the locking dogs  48  to move out of the locking groove  32 . 
     Once the locking dog  48  has moved out of the locking groove  32 , the outer tube  14  and the inner tube  12  are no longer locked together. Continued tension on the cable  74  permits the inner tube  12  to move with the locking body  19  into the interior  76  of the outer tube  14  as shown. Thus, when the locking mechanism  18  is in the unlocked position, as shown in  FIG. 4 , the inner tube  12  is free to move into the interior  76  of the outer tube  14 , thereby collapsing the hold open rod  10 . Moving the interior inner tube  12  into the outer tube  14  allows a door or hatch to which the hold open rod  10  is attached to move to a closed position. 
     Just as the locking mechanism  18  has been described as moving from a locked position to an unlocked position, the locking mechanism  18  can also move from an unlocked position as shown in  FIG. 4  to the locked position as shown in  FIG. 3 . By decreasing or releasing the tension on the cable  74 , the outer tube  12  can be pulled out of the inner tube  14 . This may also be done by moving the door (not shown) to which the hold open rod is attached to an open position. Further opening of the door may cause the spring  62  to urge the locking plug  34  away from the stop  42 . Moving the locking plug  34  away from the stop  42  may cause the angled wall  70  of the locking plug  34  to act as a camming surface against the angled portion  72  of the locking dogs  48 . As the locking dogs  48  align with the locking groove  32 , the camming action between the angled wall  70  of the locking plug  34  and the angled portion  72  of locking dogs  48  will push the locking dogs  48  into the locking groove  32 . This will lock the outer tube  14  to the inner tube  12 . Once the outer tube  14  has been locked to the inner tube  12 , the inner tube  12 , can no longer move further in or further out of the interior  76  of the inner tube  14 . 
       FIG. 5  is a cut away view of the hold open rod  10  showing the release cable  74  attached to the hook  64  of the locking mechanism  18 . The fastener  16  of the hold open rod  10  is also shown.  FIG. 5  allows perspective of the locking mechanism  18  to be seen with respect to the hold open rod  10  as a whole. The release cable  74  extends to outside of the hold open rod  10 . This allows a user to pull on the release cable  74  where it is desired to unlock the locking mechanism  18 . In some embodiments, the release cable  74  may be terminated with pull handle or other structure that will make the release cable easier to manipulate. 
     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.