Patent Publication Number: US-2023142995-A1

Title: Door Stop Mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of U.S. Provisional Pat. Application No. 63/277,243, entitled Door Stop Mechanism and filed on Nov. 9, 2021, the disclosure of which is herein incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field 
     The disclosed embodiments relate generally to the field of door mechanisms. More specifically, the embodiments relate to a door stop mechanisms for aircraft doors. 
     Description of the Related Art 
     U.S. Pat. No. 4,069,547 to Guionie et al. describes a toggle-type door stop having a pair of links pivotably coupled to one another that form a cam when moved to an open position. U.S. Pat. No. 10,954,704 to Kroening describes a door stop mechanism having a link member with an elongated slot and a fastener that slides along the slot to hold the door open. U.S. Pat. No. 6,292,978 to Lakoduk et al. describes a door stop apparatus having a guide member and a link pivotally connected to a follower. As the door opens and closes, the link pivots and the follower slides within the guide member. 
     SUMMARY 
     This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages of the invention will be apparent from the following detailed description of the embodiments and the accompanying drawing figures. 
     In an embodiment, a door stop mechanism for an aircraft includes an outer link including a first end and a second end, the outer link rotatably coupled to a door of the aircraft at the second end; and, an inner link including a first end and a second end, the inner link being rotatably coupled to a floor of the aircraft at the second end. The first end of the inner link is rotatably coupled to the first end of the outer link, and the first end of the inner link is configured to abut against the first end of the outer link to provide a hold-open position in which the door is held open. 
     In another embodiment, a door stop includes a scissor link member including a pair of links pivotably coupled together at a central pivot point. The scissor link member has a first end pivotally coupled to a door and a second end pivotally coupled to a floor. The pair of links are configured to abut against one another adjacent the central pivot point when the door is fully open such that the pair of links prevent pivoting at the central pivot point for holding the door open in a hold-open position. The scissor link member is releasable from the hold-open position such that the pair of links pivot about the central pivot point when the scissor link member is released from the hold-open position, thereby enabling closing of the door. The pair of links fold into a nested arrangement when the door is fully closed. 
     In yet another embodiment, an aircraft door stop includes a first link pivotably coupled to a door about a first pivot point; a second link pivotably coupled to a floor about a second pivot point; and a third pivot point. The first link and the second link are jointly coupled together about the third pivot point. The first link nests within the second link to form a nested arrangement when the door is closed. The first pivot point, the second pivot point, and the third pivot point are aligned with one another to form an aligned arrangement when the door is fully open. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Illustrative embodiments are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein: 
         FIG.  1 A  illustrates an outer scissor link for a door stop mechanism for some embodiments; 
         FIG.  1 B  illustrates an inner scissor link for the door stop mechanism for some embodiments; 
         FIG.  2 A  illustrates the door stop mechanism in a closed position for some embodiments; 
         FIG.  2 B  illustrates the door stop mechanism in a first intermediate position for some embodiments; 
         FIG.  2 C  illustrates the door stop mechanism in a second intermediate position for some embodiments; 
         FIG.  2 D  illustrates the door stop mechanism in an open position for some embodiments; 
         FIG.  3 A  illustrates a top view of the door stop mechanism in the open position for some embodiments; 
         FIG.  3 B  illustrates a top view of the door stop mechanism in a hold-open position for some embodiments; 
         FIG.  3 C  illustrates a close-up view of the door stop mechanism in the hold-open position for some embodiments; 
         FIG.  4 A  illustrates a connection between the outer scissor link and a door bracket for some embodiments; and 
         FIG.  4 B  illustrates a connection between the inner scissor link and a floor bracket for some embodiments. 
     
    
    
     The drawing figures do not limit the invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. 
     DETAILED DESCRIPTION 
     The following detailed description references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. 
     In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the technology can include a variety of combinations and/or integrations of the embodiments described herein. 
     Many different types of door stop mechanisms are known. Forward-hinged doors typically rely upon hinge mechanisms integrated into a side post structure, which requires a heavier load path for rotating the hinge mechanism. Door stop mechanisms may lack a hold-open feature to hold the door in an open position. Door stop mechanisms which have a hold-open feature may have the feature disposed in a spot inconvenient for someone sitting, such as a pilot, to actuate. Conventional door stop mechanisms may be too large to work in tight spaces. Further, many door stop mechanisms do not have a built-in feature for indicating a failure in the hinge mechanism. 
     Embodiments are generally directed to a door stop mechanism for use in aircraft. The door stop mechanism may be configured for forward-hinged doors and may be used to prop a door ajar in, for example, the cockpit of the aircraft. The door stop mechanism may provide improved use of limited door opening space for crew entering and exiting the aircraft. If a large force, such as a gust of wind, is applied to the door that forces the door open, the door stop mechanism may be configured to stretch and deform to aid in minimizing resulting damage to the surrounding aircraft structure. The door stop mechanism includes links that are shaped and formed of a material selected for the ability to mitigate damage to the surrounding structure, and deformation of the links due to excessive force is configured to provide a permanent set in the links to indicate a need for inspection of the surrounding structure and replacement of the links. 
     The door stop mechanism may be disposed externally to a side post structure of the aircraft, thereby allowing a lighter load path for the door stop mechanism by allowing a more effective moment arm than if the door stop mechanism was integrated into the side post structure. The door stop mechanism may comprise an inner and an outer scissor link connected to one another. The outer scissor link may be connected at a first end to the inner scissor link and at a second end to the aircraft door. The inner scissor link may be connected to the outer scissor link at a first end and to the floor at a second end. When the door is closed, the inner scissor link may nest within the arc of the outer scissor link. As the door is opened, the outer scissor link may rotate about the inner scissor link. If the door is forced open beyond the limitations of the door hinge mechanism, the outer and inner scissor links may become permanently set thereby visually indicating to crew members that the door hinge mechanism needs replacing, and that the surrounding aircraft structure should be inspected for damage. 
       FIG.  1 A  illustrates an outer link  102  for some embodiments. Outer link  102  may comprise a first end  104  and a second end  106 . In some embodiments, first end  104  is formed as a mounting bracket comprising an upper arm  108   a  and a lower arm  108   b . Arms  108   a ,  108   b  may comprise first openings  110   a ,  110   b  therethrough. First openings  110   a ,  110   b  form a pair of openings that are aligned with one another. In some embodiments, second end  106  comprises a second opening  112  therethrough. Outer link  102  may comprise a height of about 4 mm to about 20 mm. Second opening  112  may comprise a diameter of about 13 mm to about 17 mm. Broadly, outer link  102  may take various sizes depending on the specific application and forces applied to the door. Outer link  102  may have a substantially curved shape along its longitudinal axis. Outer link  102  may comprise aluminum, steel, titanium, copper, brass, and other like metals including metal alloys. 
       FIG.  1 B  illustrates an inner link  114  for some embodiments. Inner link  114  may comprise a first end  116  and a second end  118 . First end  116  may correspond to first end  104  of outer link  102 . First end  116  may comprise a first opening  110   c  therethrough. First openings  110   a ,  110   b ,  110   c  may comprise a diameter of about 6 mm to about 10 mm. In some embodiments, inner link  114  is configured to nest within the arc of outer link  102 , as illustrated in  FIG.  2 A  below. A link connector  202  may be inserted through first openings  110   a ,  110   b ,  110   c  to secure outer link  102  to inner link  114 , as described below in connection with  FIG.  2 A . 
     Second end  118  may comprise a second opening  120  therethrough. Inner link  114  may also comprise a release member  122  protruding upwardly from a top side of inner link  114  at second end  118 , as depicted in  FIG.  1 B . As discussed further below with respect to  FIGS.  3 A and  3 B , links  102 ,  114  may be configured to hold the aircraft door in an open position by pivoting about first openings  110   a ,  110   b ,  110   c  to a hold-open position in which first ends  104 ,  116  abut against each other to hold the door open. Release member  122  allows aircraft crew members to easily release the links  102 ,  114  from the hold-open position allowing the aircraft door to close and moving links  102 ,  114  towards the closed position shown in  FIG.  2 A . In some embodiments, release member  122  comprises a post having a substantially rectangular, cylindrical, pentagonal, hexagonal, octagonal, or other like shape. Release member  122  may comprise a height of about 20 mm to about 24 mm. Release member  122  may comprise a thickness or diameter of about 5 mm to about 9 mm. Release member  122  is discussed in further detail below with respect to  FIGS.  3 A and  3 B . Upon actuation, release member  122  is displaced thereby moving inner link  114  and dislodging links  102 ,  114  from abutting one another. 
     Inner link  114  may have a substantially curved shape along its longitudinal axis. Inner link  114  may comprise aluminum, steel, brass, titanium, copper, and other like metals. Inner link  114  may comprise a height (not including release member  122 ) of about 4 mm to about 8 mm. Second opening  120  may comprise a diameter of about 14 mm to about 18 mm. Broadly, inner link  114  may take various sizes depending on the specific application and forces applied to the door. 
       FIG.  2 A  illustrates door stop mechanism  200  comprising outer link  102  and inner link  114  in a closed position for some embodiments. In the closed position, inner link  114  may nest within the arc of outer link  102 . Specifically, inner link  114  and outer link  102  each have a similar curvature such that the two links are substantially aligned with one another when folded together into a nested arrangement. 
     Outer link  102  and inner link  114  may be connected together at first ends  104 ,  116  via link connector  202 . To connect outer link  102  to inner link  114 , first end  116  of inner link  114  may be inserted between arms  108   a ,  108   b  on first end  104  of outer link  102 . Link connector  202  may be inserted through first openings  110   a ,  110   b ,  110   c  disposed on first ends  104 ,  116  such that links  102 ,  114  are jointly coupled together about a central pivot point. As discussed further below with respect to  FIG.  3 A , link connector  202  may comprise a clevis pin for securing outer link  102  to inner link  114 . Inner link  114  and outer link  102  together form a scissor link member having a pair of links pivotably coupled together at the central pivot point via link connector  202  such that the pair of links provide scissor-like movement between open and closed positions. 
     Outer link  102  may be pivotably coupled to door  204  via door bracket  206 . Door bracket  206  may be substantially similar to a mounting bracket with an upper arm  208   a  and a lower arm  208   b . Second end  106  of outer link  102  may be inserted between upper arm  208   a  and lower arm  208   b . A door bracket connector  402  (see  FIG.  4 A ) may be inserted through door bracket  206  and outer link  102  (via second opening  112 ) to secure outer link  102  to door bracket  206 . Outer link  102  is configured for pivoting about door bracket connector  402  when transitioning between open and closed positions. Outer link  102  may be nested within a groove  205  of door  204  when closed. In some embodiments, door bracket  206  is fixed to door  204 . Groove  205  may comprise any indentation or opening within door  204  configured to receive a portion of outer link  102 . 
     Inner link  114  may be coupled to floor  210  via floor bracket  212 . Floor bracket  212  may be substantially similar to a mounting bracket with an upper arm  214   a  and a lower arm  214   b . Floor bracket  212  may be coupled to floor  210  adjacent a top corner of a step  216  such that upper arm  214   a  is substantially flush with floor  210  (see  FIG.  2 D ). Lower arm  214   b  may be located along the side of the step  216  which may form a step-down area for exiting the aircraft. Second end  118  of inner link  114  may be inserted between upper arm  214   a  and lower arm  214   b . A floor bracket connector  406  (see  FIG.  4 B ) may be inserted through floor bracket  212  and inner link  114  (via second opening  120 ) to pivotably secure inner link  114  to floor  210 . Inner link  114  is configured for pivoting about floor bracket connector  406  when transitioning between open and closed positions. 
       FIG.  2 B  illustrates door stop mechanism  200  in a first intermediate position for some embodiments, and  FIG.  2 C  illustrate door stop mechanism  200  in second intermediate position for some embodiments. The first intermediate position illustrates the position of door stop mechanism  200  in an early stage of opening door  204 , and the second intermediate position illustrates the position of door stop mechanism  200  in a later stage of opening door  204 . As illustrated in  FIGS.  2 B and  2 C , as door  204  opens, door stop mechanism  200  may rotate and move into a fully-opened position (see  FIG.  3 A ) whereby openings  110   a ,  110   b ,  110   c ,  112 , and  120  are substantially in-line. 
       FIG.  2 D  illustrates door stop mechanism  200  in an open position for some embodiments. When opened, outer link  102  may rotate about inner link  114 , and inner link  114  may rotate about floor bracket connector  406  (see  FIG.  4 B ). In some embodiments, inner link  114  is configured to rotate approximately 90° from the closed position to the open position. In some embodiments, outer link  102  is configured to rotate approximately 180° about link connector  202  from the closed position to the open position. In the open position, outer link  102  and inner link  114  may be substantially in-line with one another. Links  102 ,  114  may function as rigid links in operation; however, if a dynamic force is applied to door  204  (e.g., from a strong gust of wind), and door  204  is allowed to open in an uncontrolled manner, links  102 ,  114  are configured to elongate rather than instantly stopping the motion of door  204 . This elongation of links  102 ,  114  slows the stopping of door  204  over time rather than substantially instantaneously, thereby lessening the force imparted into the surrounding structure. The deformation of links  102 ,  114  caused during this event may produce a permanent set in links  102 ,  114 . By deforming links  102 ,  114 , damage to the surrounding aircraft structure may be lessened. In some embodiments, links  102 ,  114  are configured to deform at a predetermined applied load to door  204  that is known to otherwise cause damage to the surrounding aircraft structure. The thickness and curvature of links  102 ,  114  may influence the point at which links  102 ,  114  permanently set. To increase the applied load at which links  102 ,  114  are permanently deformed, links  102 ,  114  may be sized larger and/or have the arc decreased. At the permanent set point of links  102 ,  114 , the deformation due to the applied load may stay in the material after the applied load is removed. As such, links  102 ,  114  may hold their deformed shape, thus indicating that links  102 ,  114  should be replaced and the surrounding structure inspected. 
     In some embodiments, door stop mechanism  200  is configured to open without providing substantially any dampening to the opening of door  204  while door  204  is opened by about 100° from the closed position. In some embodiments, door  204  is rotatably connected to the aircraft body via door hinge mechanism  218 . Door hinge mechanism  218  may comprise one or more hinges for rotatably connecting door  204  to the aircraft body. In some embodiments, door hinge mechanism  218  of door  204  is configured such that it swings open to the hold-open position when door  204  is unlatched and allowed to move freely. 
       FIG.  3 A  illustrates a top view of door stop mechanism  200  in a fully-open position for some embodiments. As shown, door stop mechanism  200  may be considered in the fully-open position when door bracket opening  302 , link connector  202 , and floor bracket connector  304  are substantially in-line with one another, as indicated by a centerline  306 . The fully-open position of mechanism  200  also coincides with the door being fully open. In the fully-opened position, door bracket opening  302 , link connector  202 , and floor bracket connector  304  are substantially in-line with one another along centerline  306  forming an aligned arrangement. As discussed below, first ends  104 ,  116  may contact each other as links  102 ,  114  swing to a hold-open position as shown in  FIG.  3 B . 
       FIG.  3 B  illustrates door stop mechanism  200  in the hold-open position. Due to the pivot points of door stop mechanism  200  being in alignment with one another when in the fully-open position illustrated in  FIG.  3 A , when door  204  begins to close, door stop mechanism  200  is configured to continue rotating to the hold-open position shown in  FIG.  3 B . In the hold-opened position, link connector  202  has moved off centerline  306 . As discussed below with respect to  FIG.  4 B , a biasing member  408  may be employed to help push door stop mechanism  200  off centerline  306  such that the mechanism  200  automatically moves from the fully-opened position to the hold-open position when the door is fully opened. 
       FIG.  3 C  provides a close-up view of door stop mechanism  200  in the hold-open position characterized by first end  116  abutting against an inner surface of first end  104 , thereby preventing collapse of door stop mechanism  200 . First end  104   and first end  116  are adjacent to the central pivot point about link connector  202 . Consequently, a user may be prevented from closing door  204  when door stop mechanism  200  is in the illustrated hold-open position. 
     When it is desired to close door  204 , a user (e.g., a crew member) may push or pull door stop mechanism  200  inwardly via release member  122  to move the pivot point at link connector  202  out of the hold-open position. Once below centerline  306 , links  102 ,  114  may begin moving back to the semi-closed positions illustrated in  FIG.  2 C  and then  FIG.  2 B , whereby door stop mechanism  200  moves outward and collapses to the closed position shown in  FIG.  2 A . The positioning of release member  122  on inner link  114  may allow for the crew member to reach release member  122  with their foot while seated. For example, the location of release member  122  substantially near second end  118  enables the crew member to reach their foot around an obstruction (e.g., an entry ladder in a cockpit) and still access release member  122 . As such, the crew member may use their foot to move release member  122  and pull door  204  shut without having to reach down with a hand to disengage door stop mechanism  200  from the hold-open position. Alternatively, or additionally, the crew member may use their hand or a tool to pull release member  122  and shut door  204 . 
       FIG.  4 A  illustrates outer link  102  connected to door bracket  206  for some embodiments. As described above, outer link  102  may be coupled to door  204  via door bracket  206 . Second end  106  of outer link  102  may be inserted between upper arm  208   a  and lower arm  208   b  of door bracket  206 , whereby outer link  102  is secured via door bracket connector  402 . In some embodiments, door bracket connector  402  comprises screws, nuts, bolts, pins, rods, and the like. In some embodiments, door bracket connector  402  comprises a clevis fastener. In some embodiments, door bracket connector  402  comprises sleeves, spacers, springs, coils, washers, nuts, or any combination thereof along its body. Outer link  102  is configured to pivot about door bracket connector  402  for swinging between the open and closed positions described above. In some embodiments, door bracket connector  402  is secured with a first locknut  404   a . In some embodiments, first locknut  404   a  comprises a castellated locknut. 
       FIG.  4 A  also illustrates link connector  202  for some embodiments. In some embodiments, link connector  202  is configured to secure outer link  102  to inner link  114  (inner link  114  has been omitted from  FIG.  4 A  for clarity of illustration) as described above. Link connector  202  may comprise screws, nuts, bolts, pins, rods, and the like for fastening outer link  102  to inner link  114 . In some embodiments, link connector  202  comprises a clevis fastener. In some embodiments, link connector  202  comprises sleeves, spacers, springs, coils, washers, or any combination thereof along its body. In some embodiments, link connector  202  is inserted into first opening  110   a  on upper arm  108   a , into first opening  110   c  on first end  116  of inner link  114 , and into first opening  110   b  on lower arm  108   b  to secure outer link  102  to inner link  114 . 
       FIG.  4 B  illustrates inner link  114  connected to floor bracket  212 , thereby connecting inner link  114  to floor  210  (floor  210  omitted from  FIG.  4 B  for clarity of illustration) for some embodiments. Second end  118  of inner link  114  may be inserted between upper arm  214   a  and lower arm  214   b  of floor bracket  212 , whereby inner link  114  is secured via floor bracket connector  406 . In some embodiments, floor bracket connector  406  comprises screws, nuts, bolts, pins, rods, and the like. In some embodiments, floor bracket connector  406  comprises a clevis fastener. In some embodiments, floor bracket connector  406  comprises sleeves, spacers, springs, coils, washers, nuts, or any combination thereof along its body. 
     In some embodiments, floor bracket connector  406  comprises biasing member  408  thereon. Biasing member  408  is a spring (e.g., a torsion spring) in embodiments. As described above, biasing member  408  may aid in pushing door stop mechanism  200  over centerline  306 , thereby holding door  204  open. In some embodiments, when door  204  is rotated open, biasing member  408  is configured to push links  102 ,  114  over centerline  306  when door  204  reaches the end of travel. As such, door  204  may be moved into the hold-open position without substantially any user interaction. Once door  204  is unlatched, door  204  may automatically swing into the hold-open position. In some embodiments, biasing member  408  is configured to be strong enough to push door stop mechanism  200  over centerline  306 , while providing minimal resistance when the user pulls release member  122  back over-center and door  204  rotates shut. In some embodiments, floor bracket connector  406  is secured with a second locknut  404   b . In some embodiments, second locknut  404   b  comprises a castellated locknut. 
     While embodiments herein have been described with respect to using door stop mechanism  200  in an aircraft (e.g., the cockpit), door stop mechanism  200  may be utilized with various doors. Door stop mechanism  200  may be particularly useful in doors having substantially small openings. Further, door stop mechanism  200  may be useful when an external door stop mechanism is not desired. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of what is claimed herein. Embodiments have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from what is disclosed. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from what is claimed. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.