Abstract:
A knuckle assembly for mounting an electrical device includes a rotatable knuckle mount, an articulated knuckle and an electrical device mount. Two knuckle elements forming the articulated knuckle each include an open cavity, which together form a closed cavity. One of the knuckle elements is pivotally attached to the rotatable knuckle mount and the other includes the electrical device mount. A grommet is positioned in the closed cavity; and a fastener engages the knuckle elements and extends through the grommet. The grommet includes spherical or spheroidal segments complementary to the inner surfaces of the closed cavity and in interfering fit when assembled. The grommet is in non-rotational engagement with one of the knuckle elements. Wires extend through the grommet adjacent a central through hole. A fastener extending through the central through hole draws the knuckle elements together to fix the grommet and seal the assembly.

Description:
This application claims priority based on Provisional Application 61/605,708, filed Mar. 1, 2012, the disclosure of which is incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The field of the present invention is adjustable mounts for electrical devices. 
     Landscape lighting fixtures have traditionally been faced with significant challenges in precise aiming of such fixtures. Adjustment devices used to aim the fixtures must endure the rigors of being mounted in the ground where abuses from maintenance, fertilizer, water, mud, debris, vandalism, and weather extremes are commonplace. Furthermore, the mechanisms commonly are asked to articulate in multiple axes, along with being capable of routing electrical wires through the articulation. This challenge is compounded when water tightness is a requirement. 
     Existing mechanisms used to mount, adjust and aim these types of fixtures include knuckle joint assemblies and yoke or stirrup assemblies. Knuckle joint assemblies are comprised of two mating halves fixed about a central pivot point. This pivot point usually is a screw which, when tightened, locks the two halves together. Knuckle joint assemblies are affixed to the lighting fixture at a single point. Electrical supply is commonly routed through the knuckle joint assembly. To avoid loss of alignment, intermeshed teeth on mating halves have been used. The fineness of the meshed teeth determine aimability of the fixture. Tapered conical mating features also have been used to eliminate the indexing of the aiming limitations inherent with using teeth. Conical tapers rely solely on friction to overcome rotational forces, but can become frozen in place. 
     Routing wiring through the single pivot knuckle assembly usually results in chafing of the wiring. Because knuckles tend to be relatively small, tight spacing magnifies the chafing. Shorting of the wring is commonplace in this area and is usually a mode of failure for this type of fixture. Twisting of the wiring around the pivot point screw is another issue with electrical pass through routing. Adjustments where the fixture is articulated about the centerline of the knuckle stem also strains the electrical supply connections. This adjustment is generally accomplished through a standard male threaded pipe stem assembled into a female threaded hub opening. If aiming requires the position of the fixture to be different than where the male/female joint tightens, the stem can remain loose. 
     Knuckle joint assemblies usually have no provision to block water entry directly into the fixture from the electrical pathway. Seals such as O-rings are often damaged or crushed as the fixture is adjusted. Wiring routed into the fixture is loose and openings allowing the electrical entry into the fixture body are generally not sealed. 
     Yoke or stirrup type assemblies are typically affixed to the lighting fixture at two pivot points located along an axis about which the fixture pivots. Adjustment is effected when the two pivot point mechanisms are loosened, the fixture aimed, then the two pivot point mechanisms are tightened. There is typically no provision for internal electrical routing. The electrical penetration into the fixture housing must be done separately which adds another point of water entry and does not allow for clean second axis rotation. Further, the electrical connections are accessible and, therefore, subject to exposure and vandalism. If rotation and electrical supply pass through are combined at one point, that point requires separate sealing as well as a mechanism for locking the position of the fixture. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a knuckle for mounting an electrical device. The knuckle includes a rotatable knuckle mount and an electrical device mount. Two knuckle elements each include an open cavity, which together form a closed cavity. One of the knuckle elements is pivotally attaching to the knuckle mount and the other includes the electrical device mount. A grommet is positioned in the closed cavity; and a fastener engages the knuckle elements and extends through the grommet. 
     In a first aspect of the present invention, one of the knuckle elements has an inner surface of rotation about an axis perpendicular to the axis of the knuckle mount, which surface is a segment of a sphere or spheroid. The grommet includes an outer surface of rotation about the axis of the inner surface of rotation in that one knuckle element. The inner and outer surfaces of rotation are complementary with an interfering fit. The grommet is in non-rotational engagement with the other of the knuckle elements. The grommet provides infinite adjustability within the arc of motion of the knuckle. In compression, the grommet seals and locks the knuckle over the area of the segment and can more readily be released later from locking engagement. 
     In a separate second aspect of the present invention, one of the knuckle elements has an inner surface of rotation about an axis perpendicular to the axis of the knuckle mount, which surface is a segment of a sphere or spheroid. The grommet includes an outer surface of rotation about the axis of the inner surface of rotation in that one knuckle element. The inner and outer surfaces of rotation are complementary with an interfering fit. The grommet is in non-rotational engagement with the other of the knuckle elements. Wiring extends through the closed cavity and, in that closed cavity, through wire holes in the grommet. The grommet is truncated for wiring clearance; and a shoulder surrounds the fastener to protect the wiring. The grommet provides infinite adjustability within the arc of motion of the knuckle. In compression, the grommet seals and locks the knuckle over the area of the segment, seals the wiring in the wire path and can more readily be released from locking engagement. 
     In a separate third aspect of the present invention, the device of the first two aspects of the invention is enhanced by the other of the knuckle elements also having an inner surface which is a segment of a sphere or spheroid and by the grommet including an outer surface which is complementary to the adjacent inner surface. Wire holes through the grommet can be compressed by the interference fit impacting the full length of the wire holes to seal the wire path between knuckle elements. 
     In a separate fourth aspect of the present invention, any of the foregoing aspects may be combined to further advantage. 
     Accordingly, it is an object of the present invention to provide an improved mounting knuckle. Other and further objects and advantages will appear hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a mounting knuckle with an electrical device mounted thereon. 
         FIG. 2  is an exploded perspective view of the mounting knuckle. 
         FIG. 3  is an exploded perspective view of a first knuckle element and grommet. 
         FIG. 4  is a perspective view of a second knuckle element and grommet. 
         FIG. 5  is a bottom view of the first knuckle element. 
         FIG. 6  is a cross-sectional side view of the assembled knuckle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning in detail to the drawings, a knuckle for mounting electrical devices such as lamps  10  is disclosed. A knuckle mount  12  is shown to be substantially cylindrical with a passageway therethrough and threads  14  for engagement with an electrical connection supply box (not shown). The knuckle mount  12  typically extends with the axis therethrough in a vertical orientation to just above the ground in an outdoor environment. A seal groove  16  about the circumference of the mount  12  is sized to receive an O-ring seal  18 . A locking groove  20  is arranged to receive a set screw  22  upon assembly. 
     A first knuckle element  24  is rotatably mounted on the knuckle mount  12 . The set screw  22  is threaded into the locking groove  20  through a threaded hole  26 . The set screw  22  may be placed to simply retain the knuckle element  24  from separating from the knuckle mount  12  or be tightened to restrain the knuckle element  24  from rotating on the knuckle mount  12 . The O-ring seal  18  is sized to seal between the mounting cavity  28  of the knuckle element  24  and the seal groove  16 . A pin  30  is engaged with the top annular surface of the knuckle mount  12  to extend into the mounting cavity  28  and into a channel  32  in the mounting cavity  28 . The channel  32  has a stop  34  to prevent the knuckle element  24  from rotating a full 360□ or more on the knuckle mount  12  to prevent wiring extending through the interior of the knuckle mount  12  from becoming excessively twisted. 
     The knuckle element  24  includes an upstanding structural cup  36 . A first cavity  38  is defined within the structural cup  36 . In the preferred embodiment, the cavity  38  is generally hemispherical with an opening at an engagement plane  40 . 
     A second knuckle element  42  has a cylindrical mount  44  with appropriately placed threaded holes to receive an electrical device such as the lamp  10 . A gasket is shown on the cylindrical mount  44  in  FIG. 6  engaging with a groove  46  around the inner perimeter of the cylindrical mount  44 . The knuckle element  42  also has a structural cup  48 . The cup  48  defines a cavity  50  which, in the preferred embodiment, is also generally hemispherical. The cavity also opens at an engagement plane  52 . 
     Looking to the orientation of the knuckle, the knuckle mount  12  rotationally mounts the knuckle about a first axis. This axis extends along the engagement planes  40 ,  52  when assembled. A second axis through the cavities  38 ,  50  may be defined perpendicular to the rotational axis of the knuckle mount  12  and perpendicular to the engagement planes  40 ,  52 . When the engagement planes  40 ,  52  are engaged with the open cavities  38 ,  50  aligned, a closed cavity is defined which is generally spheroidal or spherical. 
     A generally spherical grommet  54  made of elastomeric material is positioned within the closed cavity defined by the open cavities  38  and  50  when the knuckle elements  24 ,  42  are positioned together. The grommet  54  has a central hole  56  to extend along the perpendicular axis. The central hole  56  is shaped to receive a tapered shoulder  58  which extends centrally in the open cavity  38 . The shoulder  58  has a central threaded hole  60 . The grommet  54  also has three engagement slots  62  equiangularly spaced about the surface of the grommet  54  which is received by the cavity  38 . The three engagement slots  62  extend in line with the central hole  56  to receive engagement fins  64  in the first cavity  38 . 
     The central hole  56  is also formed to receive a tapered shoulder  66  with a through hole  68  in the shoulder  66  extending in the open cavity  50 . The shoulder  66  is located along the perpendicular axis in the open cavity  50 . The through hole  68  extends through the wall of the structural cup  48 . Upon assembly, a fastener  72  extends through the through hole  68 , the central hole  56  of the grommet  54  and into the threaded hole  60 . The fastener  72  may be drawn in by threaded engagement with the hole  60  to bring the knuckle elements  24  and  42  together at the engagement planes  40 ,  52 . When together, the tapered shoulders  58 ,  66  do not touch in this embodiment. Thus, the grommet  54  can compress against the fastener  72  to provide sealing along the central hole  56  of the grommet  54  between the shoulders  58 ,  66 . 
     The grommet  54  is truncated about the central hole  56  on the portion extending into the cavity  50  of the knuckle element  42 . This truncation  74  relieves the grommet  54  from extending fully to the depth of the open cavity  50 . The truncation  74  provides wiring clearance around the fastener  72  located within the shoulder  66 . 
     Wire holes  76 ,  78 ,  80  extend parallel to the central hole  56  through the grommet  54 . At one end, the holes  76 ,  78 ,  80  terminate at the truncation  74 . At the other end, the wire holes  76 ,  78 ,  80  terminate at a clearance notch  82 . The clearance notch  82  aligns with a supply conductor channel  84 . The channel  84  provides a wire passageway from the mounting cavity  28  into the open cavity  38  for access to the wire holes  76 ,  78 ,  80 . A similar wire passageway  86  extends through the cylindrical mount  44 . Wiring through the wire holes  76 ,  78 ,  80  circumvents the fasteners  72  to extend through the wire passageway  86  to an electrical mounted device such as the lamp  10 . The shoulder  66  about the fastener  72  protects the wiring from the abrasive fastener threads. Thus, a first wire passageway  84  extends through the knuckle element  24  into the cavity  38  from the knuckle mount  12 . The wiring then extends through the wire holes  76 ,  78 ,  80  to the clearance provided by the truncation  74  of the grommet  54 . The wiring then extends around the shoulder  66  and through a wire passageway  86  to the electrical device. 
     In operation, the knuckle is associated with the knuckle mount  12  with the O-ring seal  18  in place. The set screw  22  is engaged with the locking groove but preferably not tightened until final aiming is performed. The grommet  54  is positioned in the cavity  38  with the engagement slots  62  receiving the engagement fins  64 . The clearance notch  82  is arranged to be adjacent the supply conductor channel  84 . Preferably wiring has been threaded through the wire holes  76 ,  78 ,  80  before such placement of the grommet  54  in the first cavity  38 . With the engagement of the fins  64  in the slots  62 , the grommet  54  is in a non-rotational engagement with the open cavity  38 . The grommet  54  has an outer surface which is a spheroidal or spherical segment complementary to the spheroidal or spherical segment of the inner surface of the cavity  38  in the knuckle element  24 . The grommet  54  may seat snuggly within the cavity  38  with a nominal outer radius of the grommet equal to the nominal inner radius of the cavity  38  when the elements are spherical. 
     The wiring extending through the grommet  54  from the truncation  74  is threaded through the wire passageway  86  to the cylindrical mount  44 . The knuckle element  42  is then positioned with the open cavity  50  over the grommet  54 . Again, the surface of the cavity  50  defines the segment of a spheroid or sphere to engage with the outer surface of the grommet  54  also defining a spheroidal or spherical segment. However, the grommet  54  and the knuckle element  42  do not fully mate because of an interference fit of the grommet  54  within the cavity  50 . With a nominal radius of the spherical cavity  50  of 0.625 inches, the spherical grommet  54  advantageously has a nominal radius of 0.635 inches. The shore hardness of the spherical grommet 90 A+/−5. 
     The fastener  72  is then threaded through the hole  68  into the central hole  56 . Aiming adjustments are made and the fastener is then tightened to draw the engagement planes  40 ,  52  together. The grommet  54  is compressed into interference fit within the cavity  50  and is also forced axially along the fastener to fit more tightly in the cavity  38 . The spherical or spheroidal grommet  54  segments are distorted with this compression to closely conform and compress against the surface segments of rotation of the interior of the cavities  38 ,  50 . Further, the wire holes  76 ,  78 ,  80  are also distorted along their length to conform and compress against wiring extending therethrough. With the knuckle thus assembled, the knuckle element  42  can no longer rotate relative to the grommet  54  which is in turn held from rotating in the knuckle element  24  by the engagement of the fins  64  in the slots  62 . Further, the grommet  54  seals between itself and the interiors of the cavities  38 ,  54  and between the wire holes  76 ,  78 ,  80  and the wiring extending therethrough. Thus, in this configuration, the knuckle is fixed and provides sealing with compression of the grommet  54  to either side of the engagement planes  40 ,  52  with the inner surfaces of the cavities  38 ,  50 . The wiring through the wire holes  76 ,  78 ,  80  is also in compression with the compressed grommet  54  to complete sealing of both the wire passageway through the knuckle element  24  and the wire passageway through the knuckle element  42 . 
     An improved mounting knuckle is described above. While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.