Abstract:
A magnetic latching system is provided for removably latching a panel to an aircraft surface portion. The latching system includes a removable axis panel engageable to a latching land. The panel and land define opposing magnetically attractive surface portions, with a body of magnetic material disposed there between. An inflatable seal is also disposed intermediate the panel and the land. Upon inflation, the inflatable seal is operative to urge the panel away from the land far enough to reconnect magnetic engagement between the panel and the land, sufficient to permit disengagement of the panel from the land.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     The present invention relates to a magnetic latching system that allows a removable axis panel to separate from a latching land when access to the aircraft interior is desired. More particularly, the present invention relates to a pneumatically driven latching system suitable for rapid removal and reinstallation of aircraft outer mold line (OML) panels and doors. 
     In the building of aircraft, both civil and military, exterior panels, doors and other structures are provided which can be removed for repair or to allow access to aircraft systems, e.g. mechanical, electrical or hydraulic, disposed within the body of the aircraft. The panel doors are preferably formed flush with the adjacent aircraft surface, to avoid interference with aerodynamic characteristics of the aircraft. Irregularities in an aircraft surface can also mitigate stealth characteristics of an aircraft, as RF signals may reflect from surface irregularities and detract from low observable characteristics of the aircraft. 
     While panels may conventionally engaged to an aircraft surface by means of screws or similar fasteners, such connecting means commonly require torqueing the fasteners to a desired pressure, can result in wear and loosening of the fasteners during use, and can preload the panels into undesirable levels. Moreover, in practical circumstances of use, fasteners can fall into the aircraft interior when installing or removing the panel, creating potentially hazardous conditions with respect to mechanical and electrical systems disposed in the vicinity. As such, alternative latching systems are desirable in order to allow for greater ease of installation and removal, avoidance of creating undue loads on panel and mitigating the prospect of accidentally releasing undesirable debris within the aircraft body which may be difficult to locate and potentially damaging to aircraft electrical and mechanical systems. Further, as noted above, it is desirable such that latching system exhibit minimal surface irregularities, to retain desired aerodynamic and low observable characteristics. Preferably, such latching system will also provide suitable sealing characteristics to facilitate airtight and watertight isolation of the aircraft electrical/mechanical/hydraulic systems, as well as mitigating the potential for noise associated with gaps between adjacent aircraft surface portions. 
     These and other objects and advantages are addressed in the present invention, which is described in exemplary terms below, in connection with the illustrated embodiments. 
     BRIEF SUMMARY 
     A magnetic latching system is provided for removably latching a panel to an aircraft surface portion. The system includes a removable access panel defining an upper surface, a lower surface and side surfaces; the lower surface defining a panel lower peripheral surface. A plurality of magnetically attractive panel surface portions are disposed along at least a portion of the panel lower peripheral surface. 
     A latching land is provided which is connectable to the aircraft surface portion. The land defines an upper surface having an outer peripheral portion that is substantially coplanar with the aircraft surface portion; a seating surface for receiving and supporting the panel lower peripheral surface; and land side surfaces. 
     The land seating surface defines a plurality of magnetically attractive land surface portions disposed along at least a portion of the land panel seating surface. 
     A body of magnetic material is disposed intermediate the magnetically attractive panel surface portions and the magnetically attractive land surface portions, the body of magnetic material being operative to form a magnetic bond between the panel and the land, to urge the panel into magnetic engagement with the land seating surface, such that it is substantially coplanar with the aircraft surface portion. 
     An inflatable seal is provided intermediate the panel and the land, substantially adjacent the magnetic material. Upon inflation, the inflatable seal is operative to urge the panel away from the land far enough to weaken magnetic engagement between the panel and the land, sufficient to permit disengagement of the panel from the land. 
     In one embodiment the inflatable seal is disposed adjacent the panel magnetically attractive surface portions and/or the land magnetically attractive surface portions. 
     The panel side surfaces and the land side surfaces may be beveled to facilitate extension of the inflatable bladder intermediate the beveled surfaces, thereby facilitating upward movement of the panel, upon inflation of the bladder. 
     The inflatable bladder may be implemented as a unitary structure extending about the panel/land peripheral surface, or as a plurality of inflatable segments disposed at space locations about the panel/land peripheral surface, or portions thereof. 
     The magnetically attractive surface portions may be formed as a result of embedding magnetically attractive material in the land/panel about at least a portion of the periphery thereof. The magnetically attractive material may alternately be adhered, or otherwise secured to one of more of the land/panel peripheral surfaces. 
     Upon inflation of the inflatable seal, the panel will separate from the land, as described above. The intermediate body of magnetic material will remain attached to either the land or the panel, depending upon which includes the thicker body of magnetically attractive material (the most attractive). A plurality of sheer pins are disposed vertically intermediate the panel and the land to maintain horizontal orientation of the panel with respect to the land and to direct separation of the panel/land in a perpendicular direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
         FIG. 1  is a top perspective view of a magnetic latching system in accordance with one embodiment of the present invention; 
         FIG. 2  is a bottom view of the magnetic latching system; 
         FIG. 3  is a top view of the magnetic latching system having the removable access panel separated from the latching land; 
         FIG. 4  illustrates the construction shown in  FIG. 3 , with an inflatable bladder and magnetic material separated from the access panel and the land; 
         FIGS. 5-8  are sectional views illustrating the inflation of the bladder to separate the access panel from the land; 
         FIG. 9  is a top perspective view of the access panel with the inflated bladder shown to be formed in segments; and 
         FIG. 10  is a top perspective view of the panel where the bladder is formed as a continuous structure, shown in an uninflated condition. 
         FIG. 11  is a top perspective view of the panel and land, with a pressure source for inflating the inflatable seal. 
     
    
    
     DETAILED DESCRIPTION 
     The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments. 
       FIG. 1  illustrates an exemplary magnetic latching system in accordance with the present invention. The exemplary magnetic latching system  10  includes a removable access panel  11  and a latching land  13 . The latching system  10  is designed to mate with an aircraft surface portion, to be substantially flush therewith. As described further below, the magnetic latching system functions to allow the removable access panel  11  to separate from the latching land  13 , e.g., when access to the interior is desired. After that, panel  11  may be magnetically reengaged to the land  13  for secure connection until removal is again desired. 
       FIG. 2  illustrates a rear view of the magnetic latching system  10 , showing the removable access panel  11  disposed within the latching land  13 . 
       FIGS. 3 and 4  provide additional detail respecting the construction of the removable access panel  11  and the latching land  13 .  FIGS. 5-8  provide cross-sectional views of the interface between the access panel  11  and the latching land  13 , to illustrate the engagement and the disengagement therebetween. 
     Referring to  FIGS. 3 and 4 , panel  11  includes a plurality of sheer pins  27  extending perpendicularly from panel  11 . The sheer pins  27  are arrayed to engage with apertures  29  formed on the surface of land  13 . The sheer pins  27  may be bonded to panel  11 , outboard or inboard of the panel lower peripheral surface. When the panel  11  is disposed on the land  13 , the sheer pins  27  extend into the apertures  29 , to maintain horizontal orientation of the panel  11  with respect to the land  13 . 
     As shown at  FIGS. 4-8 , the panel  11  includes a lower surface  12 , which defines a magnetically attractive lower peripheral surface  24 . The land  13  similarly includes a seating surface  14  which defines a magnetically attractive surface portion  26  extending thereabout, which is in substantial registry with panel surface  24  when the panel  11  and the land  13  are mated together. 
     The magnetically attractive surface portions  24 ,  26  may be formed by embedding magnetically attractive material, e.g. material containing iron, along the areas  24 ,  26 . Alternatively, the magnetically attractive surface portions  24 ,  26  may alternatively be formed by adhering, or otherwise securing strips of magnetically attractive material to the adjacent panel and land surface portions. 
     The magnetically attractive surface portions  24 ,  26  may be formed about the surface of the panel  11  or land  13  to form a continuous magnetically attractive surface region. While the embodiments shown at  FIGS. 3 and 4  include continuous surface portions  24 ,  26 , extending about the panel  11  and land  13 , it will be understood by those skilled in the art that the surface portions  24 ,  26  may be segmented about the same surface area, or some portion thereof 
     Referring again to  FIG. 4 , a body of magnetic material  23  is shown. The magnetic material  23  may be initially disposed upon land surface portion  26 , as shown in  FIG. 3 . Alternatively, the magnetic material  23  could be initially disposed upon panel surface portion  24 . In either case, the magnetic material  23  would be magnetically engaged to an adjacent region of magnetically attractive material. As such, when the panel  11  is engaged to land  13 , the magnetic material  23  will become disposed intermediate surface portions  24 ,  26 , and magnetically engaged to both magnetically attractive surface portion  24  of panel  11 , as well as magnetically attractive surface portion  26 , of land  13 , thereby magnetically securing panel  11  to land  13 . 
     As one of ordinary skill will recognize, the magnetic material  23  may be also formed in segments or may be formed as a unitary continuous structure as shown at  FIGS. 3 and 4 . 
     Referring again to  FIG. 4 , an inflatable bladder  17  is shown, which may be inflated to separate the panel  11  from the land  13 , as further described below. The bladder  17  may be formed as a continuous structure, as shown at  FIG. 4 , or may be formed as one or more segments, as shown at  FIG. 9 , illustrated in an inflated condition. 
     The inflatable bladder  17  is initially disposable substantially about the periphery  47  of panel  11 , or about the periphery  15  of land  13 . As described in more detail in relation to  FIGS. 5-8 , the inflated bladder  17  transitions from a non-inflated state, wherein the panel  11  is disposed substantially flush with land  13 , to an inflated state wherein the upper surface of panel  11  becomes elevated relative to upper surface of land  13 , allowing for removal of the panel  11  from the land  13 . 
     Referring again to  FIGS. 4, 5 and 11 , it is seen that the inflatable bladder  17  includes a connector  43  that is engageable to conduit  45  extending through a portion of panel  11 . Conduit  45  terminates at hose connector  41 , formed in housing  31 , disposed on an upper surface portion of the panel  11 . Connector  41  is engageable to a pressure source  33 , through pressure regulator  35 , conduit  37  and connector  39 , as shown at  FIG. 11 . Operation of regulator  35  allows pressurized gas to be communicated to the bladder  17 , to inflate the bladder, thereby separating the panel  11  from the land  13 . As will also be apparent from the figures, bladder  17  serves to provide a resilient barrier extending between panel  11  and land  13 , about the periphery thereof. The bladder facilitates sealing the interior surface of the aircraft from air and water that might otherwise pass into the interior of the aircraft, through gaps between the panel  11  and land  13 . The bladder  11  also mitigates the potential for wind noise arising from any such gaps when the aircraft is in flight. 
     It should be understood that various alternative configurations may be implemented to inflate the bladder  17 . For example, bladder  17  may include a connector extending from the bladder  17 , along the adjacent upper surface of panel  11 , avoiding the need for forming a conduit  45  through panel  11 , as shown at  FIG. 5 . 
     As shown at  FIGS. 5-8 , the panel defines an outer surface  51  which extends downwardly and inwardly from the upper surface of panel  11 . The land  13  describes a mating/corresponding beveled surface  15 , which extends downwardly and inwardly from the upper surface of land  13 . The inflated bladder  17  is disposed intermediate the surfaces  51  and  15 , and may also extend horizontally intermediate the surfaces  24 ,  26  of the panel and the land, respectively. When the bladder  17  is inflated the surfaces  24 ,  26  are urged to separate, as are surfaces  15 ,  51 . 
     Referring to  FIGS. 5-8 ,  FIGS. 5, 7  show the magnetic latching system  10  in a latched position, wherein the upper surface of panel  11  is disposed substantially flush with the upper surface of land  13 . Magnetic material  23  is shown in abutting contact with panel section of magnetically attractive material  24  and land section of magnetically attractive material  26 . The bladder  17  is shown as uninflated condition. 
     In  FIG. 6 , the bladder  17  is inflated, causing the panel area of magnetically attractive material  24  to separate from magnetically material  23 , forming a space  25  therebetween. As will be apparent to one of ordinary skill in the art, the magnetic material  23  remains attached to a section of the land area of magnetically attractive material  26 , as material  26  is formed to be thicker than material  24 , and the magnetic material  23  will remain attached to the thicker of the sections, when the panel  11  and land  13  are separated from their magnetically locked orientation. 
       FIGS. 7 and 8  illustrate a construction similar to  FIGS. 5 and 6 , except that, as shown at  FIG. 7 , the panel section of magnetically attracted material  24   a  is thicker than the land section of magnetically attractive material  26   a . As a result, when the bladder  17  is inflated, as shown at  FIG. 8 , the magnetic material  23  remains attached to the panel section of the magnetically attractive material  24   a , rather than the land section of the magnetically attractive material  26   a . As will be apparent to those skilled in the art, housing  31  and connector  41  may be eliminated from the construction, or removable from the surface of panel  11  until inflation of the bladder  17  is desired. In such case, the surface of panel  11  will remain substantially smooth until a pressure source is engaged to conduit  45 , e.g. by engagement of the housing  31  to a flush mounted quick connect fitting extending through the panel  11  in fluid connection with conduit  45 . 
       FIG. 9  illustrates a top perspective view of a panel  11 , where the inflated bladder  17  is shown as segments  17   a - 17   d , after the segments have been inflated. As shown in  FIG. 9 , the segments  17   a - 17   d  may inflate to extend beyond and above the surfaces  51 ,  15  of the panel  11  and land  13 , respectively. 
       FIG. 10  provides a top perspective to of the panel  11  wherein the inflated bladder  17  is formed as a continuous structure, shown in uninflated condition about the lower perimeter of panel  11 , and extending a short distance along the lower peripheral surface of panel  11 , as more clearly shown at  FIGS. 5-8 . 
     In one embodiment the panel  11  and/or the land  13  may be formed of graphite composite materials. The magnetically attractive material may be implemented as Kovar, a low expansion alloy primarily composed of iron, nickel and cobalt. The magnetic engagement of the panel  11  and land  13  typically results in a magnetic clamping of the panel/land, characterized by a pull force of between 4-24 pounds, with a Br Max of approximately 14,800 Gauss and a BH Max of approximately 15 MGOe. 
     The inflatable seal is expected to be designed to be inflatable to 100 psi or less. In one embodiment the seal is inflatable to thirty psi. 
     As indicated above, the present invention is described in connection with the illustrated embodiments, which are intended to be exemplary, but not limiting. As will be apparent to those of ordinary skill in the art, alternative constructions of panel  11 , land  13 , as well as the inflatable bladder  17  and the magnetic material  23  may be implemented without departing from the broader aspects of the present invention.