Patent Publication Number: US-8522496-B2

Title: Compression mounted window assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/807,349 filed Sep. 2, 2010, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention is directed generally to a window assembly, and more particularly, to a compression mounted window assembly for use in conjunction with a camera mounted on the exterior of an aircraft. 
     2. Background of the Related Art 
     Aircraft windows are typically installed by using external fasteners, adhesives or brazing. For example, U.S. Pat. No. 4,793,108 to Bain et al. describes a window assembly for an aircraft cabin that employs a retainer clip assembly for connecting the window to a frame, which is then connected as an assembly to the skin of the aircraft. In another example, U.S. Pat. No. 7,143,979 to Wood et al. describes an aircraft windshield wherein a metal edge is bonded to the windshield and the metal edge is then attached by fasteners to frame members of the aircraft&#39;s fuselage. 
     Prior art aircraft window assemblies that include frames and fasteners, such as those described in Bain et al. and Woods et al., do not present smooth aerodynamic surfaces that are flush with the aircraft fuselage. As a result, these prior art window assemblies can produce unnecessary drag. In addition, an inordinate amount of labor is required to install and replace the windows with supporting fasteners and frames. Furthermore, the fasteners and frames provide a potential leak path for moisture and air. 
     It would be beneficial to provide a window assembly for an aircraft that can be easily and efficiently installed and replaced without the use of external fasteners, frames, adhesives, brazing or any other process, so as to reduce aerodynamic drag and attendant labor costs. The subject invention satisfies those need by providing a window assembly that is readily mounted in a housing by compression. 
     SUMMARY OF THE INVENTION 
     The subject invention is directed to a compression mounted window assembly that includes a circular window having opposed front and rear planar surfaces and an outer periphery having at least one chamfered edge surface, a compressible material circumscribing the outer periphery of the window, a housing having a portal defining an annular seat for accommodating the window circumscribed by the gasket, an annular bezel operatively associated with the housing for compressively mounting the window assembly within the annular seat of the portal, and means for securing the bezel to the housing, wherein at least one of the annular seat and the annular retainer has a chamfered abutment surface that corresponds to the at least one chamfered edge surface of the window. Preferably, the window is configured from clear impact resistant material, such as sapphire, and the compressible material is configured from a silicone based elastomeric, such as a flurosilicone. 
     In one embodiment of the subject invention, the chamfered edge surface extends from the front surface of the window and the annular retainer has a corresponding chamfered abutment surface. In another embodiment of the subject invention, the chamfered edge surface extends from the rear surface of the window and the annular seat has a corresponding chamfered abutment surface. In yet another embodiment of the subject invention, the chamfered edge surface extends from the front surface of the window and the annular seat has a corresponding chamfered abutment surface. 
     Preferably, the outer periphery of the window includes a forward facing chamfered edge surface that extends from the front surface of the window and a rearward facing chamfered edge surface that extends from the rear surface of the window. In this embodiment, the annular seat has a first chamfered abutment surface that corresponds with the forward facing chamfered edge surface and the annular retainer has a second chamfered abutment surface that corresponds with the rearward facing chamfered edge surface. The forward and rearward facing chamfered edge surfaces of the window converge at a peripheral land area and define relative angles. Preferably, the forward and rearward facing chamfered edge surfaces define complementary angles, and more preferably, the complementary angles formed by the forward and rearward facing chamfered edge surfaces are 45° angles. 
     The compression mounted window assembly further includes means for mating the retainer with the housing. In one instance, the mating means includes a threaded locking ring for securing the retainer with the housing. Alternatively, the mating means includes a plurality of threaded fasteners for securing the retainer with the housing. Preferably, means are operatively associated with the rear surface of the window for heating the window to prevent icing. In one instance, the heating means includes a foil ring applied to the rear surface of the window. Alternatively, the heating means includes a film applied to the rear surface of the window. 
     The subject invention is also directed to a compression mounted window assembly that includes a circular window having opposed front and rear planar surfaces and an outer periphery having forward and rearward facing chamfered edge surfaces. A compressible gasket circumscribes the outer periphery of the window, and a housing is provided having a portal that defines an annular seat for accommodating the window circumscribed by the gasket. The annular seat has a first chamfered abutment surface corresponding with the forward facing chamfered edge surface of the window, and an annular bezel is operatively associated with the housing for compressively retaining the window assembly within the annular seat of the portal. The bezel has a second chamfered abutment surface corresponding with the rearward facing chamfered edge surface of the window. Preferably, the window assembly further includes a means for securing the bezel to the housing. The securing means can be in the form of a threaded locking ring or a plurality of threaded fasteners. 
     The subject invention is also directed to a method of compressively mounting a window assembly in a housing having a portal defining an annular seat, wherein the method includes the steps of providing a circular window having front and rear planar surfaces and an outer periphery having forward and rearward facing chamfered edge surfaces, circumscribing the outer periphery of the window with a compressible gasket, seating the window in the portal, and compressively retaining the window in the annular seat of the portal. Preferably, the step of compressively retaining the window in the annular seat includes applying compression in radial and axial directions relative to the front and rear planar surfaces of the window. However, it is envisioned and well within the scope of the subject disclosure that the step of compressively retaining the window in the annular seat could be accomplished by applying compression in a direction parallel to the front and rear surfaces of the window, such as by applying compressive force using a radial clamp. 
     These and other aspects of the subject invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those having ordinary skill in the art to which the subject invention pertains will more readily understand how to make and use the subject invention, preferred embodiments thereof will be described in detail hereinbelow with reference to the drawings, wherein: 
         FIG. 1  is a perspective view of the aft end of an aircraft that includes an exterior camera pod containing the compression mounted window assembly of the subject invention; 
         FIG. 2  is a cross-sectional view of the exterior camera pod shown in  FIG. 1 ; 
         FIG. 3  is an enlarged localized view of the compression mounted window assembly shown in  FIG. 2  mounted within the camera pod housing; 
         FIG. 4  is an exploded side elevational view of the compression mounted window assembly shown in  FIG. 2 , with each of the component parts shown in cross-section, with the exception of the window itself; 
         FIG. 5  is an exploded perspective view of the window assembly of the subject invention; 
         FIG. 6A  is a top plan view of the sapphire window of the window assembly; 
         FIG. 6B  is a side elevational view of the sapphire window of the window assembly; 
         FIG. 7A  is a top plan view of the threaded locking ring of the window assembly; 
         FIG. 7B  is a side elevational view of the threaded locking ring of the window assembly, in partial cross-section; 
         FIG. 8A  is a top plan view of the bezel of the window assembly; 
         FIG. 8B  is a cross-sectional view of the bezel taken along line  8 B- 8 B of  FIG. 8A ; 
         FIG. 8C  is a bottom plan view of the bezel of the window assembly; 
         FIG. 9  is a partial cross-sectional view of an another embodiment of the compression mounted window assembly of the subject invention, wherein the window has a single forward facing chamfered surface that corresponds to a chamfered abutment surface of the annular bezel; 
         FIG. 10  is a view of the component parts of the compression mounted window assembly shown in  FIG. 9 , which are separated for ease of illustration; 
         FIG. 11  is a partial cross-sectional view of yet another embodiment of the compression mounted window assembly of the subject invention, wherein the window has a single rearward facing chamfered surface that corresponds to a chamfered abutment surface in the annular seat of the housing; 
         FIG. 12  is a view of the component parts of the compression mounted window assembly shown in  FIG. 11 , which are separated for ease of illustration; 
         FIG. 13  is an cross-sectional view, similar to  FIG. 3 , of another embodiment of the compression mounted window assembly of the subject invention, wherein the window has a single forward facing chamfered surface that corresponds to a chamfered abutment surface in the annular seat of the housing and the bezel has a circular seat that corresponds to a rearward facing circular surface of the window; 
         FIG. 14  is an exploded side elevational view of the compression mounted window assembly shown in  FIG. 13 , with each of the component parts shown in cross-section, with the exception of the window itself; 
         FIG. 15  is a partial cross-sectional view of still another embodiment of the compression mounted window assembly of the subject invention, wherein the window has a single rearward facing chamfered surface that corresponds to a chamfered abutment surface in the annular seat of a bezel; and 
         FIG. 16  is a view of the component parts of the compression mounted window assembly shown in  FIG. 15 , which are separated for ease of illustration. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein like reference numerals identify similar structural elements or features of the subject invention, there is illustrated in  FIG. 1 , the aft or tail section of an aircraft  10  outfitted with an external camera housing  12  that includes the compression mounted window assembly of the subject invention, which is designated generally by reference numeral  100 . In this configuration, the external camera  12  is adapted and configured to provide a visual aid to pilots when taxiing at airports in and around the ramps and aprons. 
     While the subject invention is described and illustrated herein with respect to a camera for use in a particular aerospace application, it should be readily apparent to those having ordinary skill in the art that the compression mounted window assembly of the subject application can be used in other applications as well, where there is a need for a self-centering window assembly that can be mounted in a housing, frame or shroud without the use of any adhesives, brazing or external fasteners. Other applications may include window assemblies for land-based vehicles, watercraft, lighting or electronic devices. 
     Referring now to  FIG. 2 , the compression mounted window assembly  100  of the subject invention is mounted in such a manner so that the exterior surface of the window is substantially flush with the exterior surfaces of the camera housing  12 . In this way, the window assembly  100  does not impact the air stream flowing over the surfaces of the camera housing  12  while the aircraft  10  is in flight. Consequently, the compression mounted window assembly  100  of the subject invention does not create unnecessary drag. 
     Referring now to  FIGS. 3 through 5 , the compression mounted window assembly  100  is positioned within a circular portal  14  formed in the camera housing  12 . The portal  14  of housing  12  defines an annular seat  15  having a chamfered abutment surface  16  and an internally threaded region  18 . 
     The window assembly  100  includes a clear, single crystal sapphire (Al 2 O 3 ) window  110  which is both heat and impact resistant. Moreover, the window  110  is configured to withstand high speed ballistic impacts with ice, hail and gravel, while the aircraft in-flight, during take-off and landing and while taxiing. As best seen in  FIGS. 6A and 6B , window  110  is a circular component having front and rear planar surfaces  112  and  114 . Window  110  has an outer periphery defined by a forward facing chamfered edge surface  116  extending from the front surface  112 , a rearward facing chamfered edge surface  118  extending from the rear surface  114 , and a peripheral land area  120  where the edge surfaces  116  and  118  converge. The forward facing edge surface  116  corresponds with the chamfered abutment surface  16  of the annular seat  15  in portal  14 . 
     The forward and rearward facing chamfered edge surfaces  116  and  118  of window  110  define relative angles, which are preferably complementary angles, and in a preferred embodiment, the complementary angles formed by the forward and rearward facing chamfered edge surfaces  116  and  118  are 45° angles. The double chamfer provides compressive radial forces on the window  110 , when mounted in the housing  12 , which can increase the impact resistance of the window. In addition, the chamfered surfaces  116  and  118  provide a self-centering effect for the window assembly  100 . 
     Referring again to  FIGS. 3 through 5 , the window assembly  100  further includes a compressible material  125  that is configured to circumscribe the outer periphery of the window  110 . Preferably, the compressible material  125  is configured as a molded gasket adapted to fully encompass the edge surfaces  116  and  118 , as well as the land area  120  defining the periphery of the window  110 . More particularly, compressible gasket  125  includes a forward portion  126  configured to circumscribe the forward facing edge surface  116  of window  110 , a midsection  127  configured to circumscribe the peripheral land area  120  and a rearward portion  128  configured to circumscribe the rearward facing edge surface  118 . 
     The gasket  125  is preferably formed from an elastomeric material, such as, for example a fluoroelastomer or fluoropolymer. The material from which the gasket  125  is made preferably has a durometer of between  40  and  80 , and more preferably, the durometer of the gasket material is between  55  and  65 . It is envisioned that the compressible material could consist of a potting compound or adhesive which is applied to the window  110  so as to circumscribe the entire periphery thereof. 
     With continuing reference to  FIGS. 3 through 5 , window assembly  100  further includes an annular bezel  130  for compressively retaining the window  110  in the seat  15  of the portal  14  of camera housing  12 . As best seen in  FIG. 8B , the retaining bezel  130  has a chamfered abutment surface  136  that corresponds with the rearward facing chamfered edge surface  116  of the window  110 . More particularly, the angle of the chamfered abutment surface  136  of bezel  130  corresponds to the angle of the rearward facing edge surface  118  of window  110 . As best seen in  FIG. 8A , the retaining bezel  130  preferably includes a radially outwardly extending stem  132  for installing the bezel in the portal and adjusting or otherwise maintaining its position relative to the compressible gasket  125  and window  110  during installation. 
     Window assembly further includes a threaded locking ring  140 , which is adapted and configured for threaded engagement with the portal  14  of camera housing  12  to compressibly urge the retaining bezel  130  forward against the compressible gasket  125  and window  110 . As best seen in  FIGS. 5 and 8B , the rearward portion of the bezel  130  includes annular flange  134  that is dimensioned and configured to intimately engage the interior of locking ring  140  during assembly (see  FIG. 3 ). This ensures that the two components ( 130 ,  140 ) are coaxially aligned with one another and centered in the portal  14 , so that the locking ring  140  exerts equal compression over the circumference of the bezel  130 . As best seen in  FIGS. 7A and 7B , the locking ring  140  has a plurality of circumferentially disposed radial slots  142   a - 142   d  to accommodate a turning tool (not shown) for readily installing and removing the locking ring  140 . 
     Referring again to  FIGS. 3 through 5 , window assembly  100  further includes a resistive heating element  150  that is operatively associated with the rear surface  114  of the window  110  for heating the window  110  to prevent condensation and ice accretion. The resistive heating element  150  consists of a foil element  154  applied to the rear surface  114  of the window  110 . Those skilled in the art will readily appreciate that the geometry and size of the foil heater can vary depending upon the intended use of the window without departing from the spirit or scope of the subject disclosure. For example, the foil heater can be configured so that it has a circular outer periphery and a rectangular inner periphery. 
     In an alternative embodiment of the invention, the heating element  150  may be in the form of a conductive film that is applied to the rear surface  114  of the window  110  through conventional sputtering techniques. The foil element  154  includes a connector tab  156  that is adapted and configured to communicate with a wire harness  160 , as illustrated in  FIG. 4 . As best seen in  FIGS. 4 and 8C , the bezel  130  has a radial slot  138  for accommodating the connector flange  156  of heating element  150 , so that it does not become sandwiched between the bezel  130  and threaded locking ring  140  during assembly. 
     During the installation of window assembly  100  in the portal  14  of camera housing  12 , the gasket  125  is wrapped around the circular window  110 . The window  110  is then positioned in the portal  14  of the housing  12 . At such a time, the forward portion of the gasket  125  circumscribing the forward facing edge surface  116  of window  110  is in intimate contact with the chamfered abutment surface  16  defined by the seat  15  in the portal  14  of housing  12 . Then, the retaining bezel  130  is positioned behind the window  110  so the chamfered abutment surface  136  of bezel  130  is in intimate contact with the rearward portion  128  of the gasket  125 . Finally, the locking ring  140  is mated with the rear flange  134  of the bezel  130  as it is threadably engaged in the portal  14 . While the locking ring  140  is being threadably engaged, the stem  132  on retaining bezel  130  may be held so as to ensure the relative rotational position of the bezel is maintained within the assembly. 
     Thereupon, the window  110  is compressed between the chamfered abutment surface  136  of bezel  130  and the chamfered abutment surface  16  of housing portal  14 . The act of mounting window  110  in this manner compresses the surrounding gasket  125 , which ensures an effective seal against moisture and air, while maintaining thermal isolation of the window  110  from the housing  12 . Those skilled in the art will readily appreciate that the compressive forces generated by the chamfered abutment surfaces ( 16 ,  136 ) have directional components in the radial and axial directions relative to the front and rear planar surfaces  112 ,  114  of window  110 . These compressive forces advantageously provide impact strength to the window. 
     Referring to  FIGS. 9 and 10 , there is illustrated another embodiment of the compressible window assembly of the subject invention which is designated generally by reference numeral  200 . Window assembly  200  includes a circular window  210  having front and rear planar surfaces  212  and  214 . Window  210  also includes an outer periphery defined by a forward facing chamfered edge surface  216  extending from the front surface  212  and a peripheral land area  220  extending from the rear surface  214 . A compressible gasket  225  circumscribes the outer periphery of the window  210 , and includes a forward portion  226  configured to circumscribe the forward facing edge surface  216  of window  210  and rearward section  227  configured to circumscribe peripheral land area  220 . 
     Window assembly  200  further includes an annular bezel  230  adapted and configured to compressibly retain the window  220  in the circular portal  414  of housing  412 . More particularly, the retaining bezel  230  has a chamfered abutment surface  236  that corresponds with the rearward facing chamfered edge surface  216  of window  210 . A plurality of threaded fastener  240  are provided for fastening the bezel  230  within a seat  415  formed in the housing  412 , and thereby compressibly retain the window  210  in the portal  414 . 
     Referring now to  FIGS. 11 and 12 , there is illustrated yet another embodiment of the compressible window assembly of the subject invention, which is designated generally by reference numeral  300 . Window assembly  300  includes a circular window  310  having front and rear planar surfaces  312  and  314 . Window  300  further includes an outer periphery defined by a rearward facing chamfered edge surface  318  extending from the rear surface  314  and a peripheral land area  320  extending from the front surface  312 . A compressible gasket  325  circumscribes the outer periphery of the window  310 , and includes a rearward portion  328  configured to circumscribe the rearward facing edge surface  318  of window  310  and a forward section  327  configured to circumscribe peripheral land area  320 . 
     In this embodiment of the subject invention, the chamfered edge surface  318  corresponds with a chamfered abutment surface  516  formed in the portal  514  of housing  512 . Window assembly  300  further includes an annular bezel  330  adapted and configured to compressibly retain the window  310  in the circular portal  514  of housing  512 . Bezel  300  includes an annular seat  350  for accommodating a portion of the peripheral land area  320  circumscribed by the forward section  327  of gasket  325 . A plurality of threaded fasteners  340  are provided for fastening the bezel  330  within a seat  515  formed in the housing  512 , and thereby compressibly retaining the window  310  in the portal  514 . 
     Referring to  FIGS. 13 and 14 , there is illustrated still another embodiment of the compression mounted window assembly of the subject invention, which is designated generally by reference numeral  600 . Window assembly  600  includes a window  610  having front and rear planar surfaces  612  and  614 . Window  610  has an outer periphery defined by a forward facing chamfered edge surface  616  extending from the front surface  612  and a rearward facing circular edge surface  618  extending from the rear surface  614 . The forward facing edge surface  616  corresponds with the chamfered abutment surface  16  of the annular seat  15  in portal  14 . 
     Window assembly  600  further includes a compressible gasket  625  that is configured to circumscribe the outer periphery of the window  610 . More particularly, compressible gasket  625  includes a forward portion  626  configured to circumscribe the forward facing chamfered edge surface  616  of window  610  and a rearward portion  628  configured to circumscribe the rearward facing circular edge surface  618 . 
     Window assembly  600  also includes an annular bezel  630  for compressively retaining the window  610  in the seat  15  of the portal  14  of housing  12 . The bezel  630  has a circular seat  636  that corresponds with the rearward facing circular edge surface  618  of window  610 . Window assembly  600  further includes a threaded locking ring  640 , which is adapted and configured for threaded engagement with the portal  14  of housing  12  to compressibly urge the retaining bezel  630  forward against the compressible gasket  625  and window  610 . As best seen in  FIG. 13 , the rearward portion of the bezel  630  includes annular flange  634  that is dimensioned and configured to intimately engage the interior of locking ring  640  during assembly. Window assembly  600  also includes a resistive heating element  650  that is operatively associated with the rear surface  614  of window  610  for heating the window  610  to prevent condensation and ice accretion. 
     Referring now to  FIGS. 15 and 16 , there is illustrated a further embodiment of the compressible window assembly of the subject invention, which is designated generally by reference numeral  700 . Window assembly  700  includes a circular window  710  having a front planar surface  712  and a rear planar surface  714 . Window  700  further includes an outer periphery defined in part by a rearward facing chamfered edge surface  718  extending from the rear surface  714 . A compressible gasket  725  circumscribes the outer periphery of window  710 , and it includes a rearward portion  728  configured to circumscribe the rearward facing chamfered edge surface  718  of window  710 . 
     In this embodiment of the subject invention, the chamfered edge surface  718  corresponds with a chamfered abutment surface  716  formed in an annular bezel  730  adapted and configured to compressibly retain window  710  in the circular portal  514  of housing  512 . A plurality of threaded fasteners  740  are provided for fastening the bezel  730  within a seat  515  formed in the housing  712 , and thereby compressibly retaining the window  710  in the portal  514 , as illustrated in  FIG. 15 . 
     While the subject invention has been described with respect to preferred and exemplary embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as described herein.