Abstract:
Gravity hinge assembly which does not rely upon an axial rod or pintle to maintain axial alignment between the cam cylinders. The assembly incorporates an inter-connective attachment arrangement between the upper rotating cam cylinder and the door connection plate to form a simplified operative connection between the door and the upper cam cylinder while maintaining axial stability.

Description:
TECHNICAL FIELD 
   This invention relates to a hinge assembly and more particularly to a gravity actuated hinge utilizing an arrangement of cam surfaces which are displaceable upon movement of a supported door assembly. The cam surfaces return to a predetermined position upon release of such door assembly so as to provide self-actuated return of the door assembly to such predetermined position. A construction method for the hinge assembly is also provided. 
   BACKGROUND OF THE INVENTION 
   Gravity door hinges are well known in the art. Such hinges typically include a fixed cam cylinder member having an inclined cam surface on its upper end and a rotatably and vertically displaceable cam cylinder member including a complementary cam surface on its lower end. An axial rod is inserted through the cam cylinder members such that the two inclined cam surfaces abut each other in a complementary relationship. The rotational cam member is operatively connected to a door such that when the door is opened by pushing or pulling, the door is slightly raised as the upper cylinder member is rotated relative to the lower cylinder member and the angled cam surfaces are brought out of complementary aligned relationship. As a consequence, when the pushing or pulling force is relieved, gravity causes the upper cam surface to retreat to its original complementary orientation relative to the lower stable cam surface. 
   In order to achieve the desired cooperative relationship between the cam surfaces of the prior hinge structures while also promoting extended useful life without failure, it has been necessary to utilize finely machined and heat treated metallic cylinder elements which are tapped to accept and retain the connecting axial rod in a stable orientation. The use of such manufacturing processes gives rise to substantial complexity in the assembly process. In addition, over a period of prolonged use, heat treated metallic materials may be susceptible to deformation. In particular, the cam surfaces may become abraded thereby resulting in edge deformities reducing the smoothness of the opening and closing operation. Moreover, if the axial rod itself is damaged, then the ability to achieve aligned rotation may be hindered or lost. 
   SUMMARY OF THE INVENTION 
   The present invention provides advantages and alternatives over the prior art by providing a gravity actuated hinge assembly which does not rely upon an axial rod or pintle to maintain axial alignment between the cam cylinders. In addition, the cam cylinders are formed from self-lubricating polymeric materials such that abrasion and consequent deformation is greatly reduced. The present invention also incorporates an inter-connective attachment arrangement between the upper rotating cam cylinder and the door connection plate to form a simplified operative connection between the door and the upper cam cylinder. The selection of cylinder cam materials further aides in simplifying the connection of the stationary lower cam cylinder in place relative to a supporting mounting bracket. 
   According to one aspect of the present invention, a gravity actuated hinge assembly is provided including a complementary pair of self-lubricating cam cylinders formed from a polymeric material such as nylon or the like infused with a friction activated lubricant such as molybdenum, graphite, or the like. The upper cam cylinder is displaceable relative to the lower cam cylinder upon rotation of an operatively attached door such that the upper cam cylinder is raised away from the lower cam cylinder when the door is moved. The upper cam cylinder is operatively connected to the door by a plate assembly embedded in seated relation in a depression within the head of the upper cam cylinder such that direct axial translation between the door and the upper cam cylinder is communicated through the connection plate. 
   It is to be understood that other aspects, advantages, and features of the invention will become apparent through a reading of the following detailed description of the invention and/or through use of the invention. Accordingly, such description is to be understood to be exemplary and explanatory only and in no event is the invention to be limited to any illustrated and described embodiments. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the principals of this invention within the true spirit and scope thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described by way of example only, with reference to the accompanying drawings which are incorporated in and which constitute a part of this specification herein and together with the general description of the invention given above, and the detailed description set forth below, serve to explain the principles of the invention wherein: 
       FIG. 1  is an exploded view of a prior art gravity actuated hinge assembly; 
       FIG. 2  is a view similar to  FIG. 1  illustrating an exemplary embodiment of a gravity actuated hinge assembly according to the present invention; 
       FIG. 3  is a partially cut-away view of the hinge assembly of  FIG. 2  in an installed position relative to a door and supporting wall shown in phantom; 
       FIG. 4  is a view illustrating an exemplary interlocking seated relationship between a rotatable cam cylinder and a hinge door connection plate taken generally along line  4 — 4  in  FIG. 3 ; and 
       FIG. 5  is a view illustrating an integral anti-rotation nipple disposed across the underside of a stationary cam surface as viewed generally along line  5 — 5  in  FIG. 2 . 
   

   DETAILED DESCRIPTION 
   Reference will now be made to the drawings wherein, to the extent possible, like reference numerals are utilized to designate corresponding components throughout the various views. For reference purposes only, in  FIG. 1  there is illustrated an exemplary prior art gravity actuated hinge assembly  10 . As will be appreciated, the hinge assembly  10  includes an upper pivot portion  12  providing a rotatable attachment between a support wall and an upper portion of a swinging door in a manner as will be well know to those with skill in the art. The hinge assembly  10  further includes a lower pivot portion  14  which is likewise adapted to provide a hinging connection between a lower portion of the door and the support wall. 
   As illustrated, the upper pivot portion  12  includes an upper connection plate  16  including a pair of screw acceptance openings  18  sized to receive attachment screws  20  therethrough such that the screws  20  affix the connection plate  16  to a surface of a swinging door (not shown). As shown, the screw acceptance openings  18  are preferably flared at the upper surface of the connection plate  16  so as to permit the screws  20  to be installed flush with the upper surface. The upper connection plate  16  also includes a stud acceptance opening  22  adapted for receipt and retention of a reduced diameter portion of a stud element  24 . The stud element  24  has a substantially cylindrical configuration including a chamfered upper edge such that it can ride in sliding relation within a split bushing  26  which is held in place within a leg of top pivot bracket  28 . The top pivot bracket  28  may be secured to a support wall (not shown) by screws projecting through bracket openings  30 . As will be appreciated, the construction of the upper pivot portion  12  is such that an attached door may be slightly raised and lowered by application of appropriate force with such change in elevation resulting in a sliding repositioning of the stud element  24  while the top pivot bracket  28  remains stationary. 
   In the prior art construction, the lower pivot portion  14  includes a lower connection plate  32  including screw acceptance openings  34  adapted to receive screws  36  for insertion in fixed relation to a lower portion of a hinging door structure (now shown). The lower connection plate further includes an acceptance opening  38  for acceptance of an upwardly projecting nipple  40  disposed on the upper surface of a rotating cam cylinder  42 . A roll pin  45  extends across the lower connection plate  32  and into the upper surface of the rotating cam cylinder  42  such that rotation of the lower connection plate  32  as the door is pivoted is translated to the rotating cam cylinder  42 . 
   In the prior art device the rotating cam cylinder  42  is held in axial alignment with a complementary stationary cam cylinder  44  by an axial rod or pintle  46  which extends between tapped axial acceptance openings within the caming surfaces of the cam cylinders. A containment sleeve  50  provides additional support against transverse dislocation. The stationary cam cylinder  44  includes an outwardly projecting threaded nipple  52  which projects through a pair of corresponding lock washers  54 ,  56 . The stationary cam cylinder  44  is thereafter held in place by a cooperating nut  58 . 
   As previously explained, when the attached door is rotated, the rotating cam cylinder  42  is caused to rotate relative to the stationary cam cylinder  44  thereby causing the rotating cam cylinder  42  and the attached door to slightly rise. This rise in the door is accommodated at the upper pivot portion  12  by the stud element  24  sliding upwardly through the bushing  26 . Once the pushing or pulling force which has opened the door is released, gravity causes the rotating cam cylinder  42  to fall back to its standard position with its caming surface in complementary planer relation with the caming surface of the stationary cam cylinder  44 . 
   While the hinge structure of the prior art illustrated in  FIG. 1  is highly reliable, its manufacture and assembly is relatively complex and requires a substantial degree of skill. The present invention provides the functional benefits of the prior art construction while simultaneously eliminating substantial complexity and reducing the overall number of components required. 
   Looking now to  FIGS. 2 and 3  an exemplary hinge assembly  110  is illustrated. In these figures, elements corresponding to those previously described in relation to the prior art are designated by like reference numerals increased by  100 . As illustrated, according to the exemplary and potentially preferred embodiment, the upper pivot portion  112  may be formed in substantially the same configuration as the upper pivot portion  12  of the prior art assembly illustrated and described in reference to  FIG. 1 . However, according to a potentially preferred practice, the bushing  126  is a solid bushing rather than a split bushing. As will be appreciated, this upper pivot portion  112  forms an operative connection between an upper portion of a door  162  and a wall or other stationary support  164 . 
   According to the illustrated construction, the lower pivot portion  114  utilizes a construction which eliminates the need for an axial rod or pintle to maintain the axial alignment of the rotating cam cylinder  142  and the stationary cam cylinder  144 . In addition, in the illustrated construction the need for lock washers to hold the stationary cam cylinder  144  in place has been eliminated. 
   As shown, in the illustrated arrangement, the rotating cam cylinder  142  is preferably secured in fixed axial and rotational position relative to the lower connection plate  132 . That is, the rotating cam cylinder  142  is held in position against the lower connection plate  132  and cannot rotate relative to the lower connection plate  132 . According to the potentially preferred practice, in order to establish and retain this relative stability between the connection plate  132  and the rotating cam cylinder  142 , a screw  170  or other attachment device is extended through an opening within the connection plate  132  and into the body of the rotating cam cylinder  142 . 
   In order to provide further stability, it is contemplated that the lower connection plate  132  will, itself be configured so as to be seated in anti-rotational relation to the upper portion of the rotating cam cylinder  42 . One exemplary configuration for such a seated configuration is illustrated through simultaneous reference to  FIGS. 2–4 . As shown in this arrangement, the upper portion of the rotating cam cylinder  142  is provided with a pattern of discontinuous raised walls  174  which form a depression into which a central portion of the connection plate  132  holding the attachment screw  170  may be inserted in a seated relation. As illustrated, the geometry of the portion of the connection plate  132  which is seated between the walls  174  is preferably such that substantial independent rotation is prevented. That is, preferably the connection plate  132  and the raised walls  174  engage one another in a substantially gear-like manner such that rotation of one is translated to the other. 
   In the illustrated embodiment the connection plate  132  has a substantially scalloped edge profile so as to form a tri-lobal plan geometry thereby facilitating mating the interior with the substantially circular seating depression defined by the discontinuous walls  174 . However, virtually any other complementary geometry may also be used. Preferably, the height of the walls  174  is approximately equal to the thickness of the connection plate  132  so as to provide an essentially flat contact surface with the lower edge of the door  172 . Surprisingly, it has been found that the combination of the screw attachment and depression seated connection plate  132  relative to the rotating cam cylinder  142  provides excellent long-term positional stability of the rotating cam cylinder  142  along a fixed axis of rotation even in the absence of a central pintle element. 
   According to the illustrated and potentially preferred embodiment, the fixed rotational and axial position of the stationary cam cylinder  144  is preferably maintained by a fitted geometric complementary relation between a polygonal base portion  180  of the threaded nipple  152  and a nipple acceptance opening  182  within the lower pivot bracket  158 . Thus, the acceptance opening within the lower pivot bracket will preferably have substantially the same size and shape as the base portion  180  of the nipple  152 . By way of example only, and not limitation, an exemplary plan view of the threaded nipple extending away from the underside of the rotating cam cylinder  144  with a square base portion  180  is illustrated in  FIG. 5 . Of course, any other suitable geometry for the base portion  180  may be utilized which prohibits rotation relative to the pivot bracket  158 . A complementary nut  160  which engages the threaded portion of the nipple serves to lock the stationary cam cylinder  144  in place against undesired axial movement. Such an arrangement eliminates the need for separate lock washers. 
   The elimination of axial rods or pintles to provide relative alignment of the cam cylinders  142 ,  144  avoids the need for complex tapping of pintle acceptance openings. Thus, if desired, the cam cylinders may be substantially solid with flat planar contacting surfaces. Of course, the cam cylinders may also have other constructions such as a cup-shaped structure wherein the rim acts as the camming surface as will be well known to those of skill in the art. 
   In addition to the elimination of the need to tap pintle acceptance openings, the elimination of the rigid axial alignment element (which is typically formed from hardened metal) extending between the cam cylinders may also enhance the ability to use non-metallic materials of construction to form one or both cam cylinders. In the present instance, applicants have found that suitable polymeric materials such as nylon or the like may be used to form one or both cam cylinders. Of course other materials including other polymers and/or metals suitable for use in a given environment may be used if desired. In the event that a polymeric is utilized in one or both cam cylinders, according to one potentially preferred practice, such materials may be infused with a self-activating lubricant material such as graphite, molybdenum or the like which is activated by friction between the cam surfaces. Such self-lubrication substantially eliminates the need for the introduction of lubricants during use and thereby promotes the overall lifespan of the structure. 
   As will be appreciated, while the present invention has been illustrated and described in relation to various potentially preferred embodiments, constructions, and procedures, it is to be understood that such embodiments, constructions, and procedures are illustrative only and that the present invention is in no event to be limited thereto. Rather, it is contemplated that modifications and variations embodying the principles of the invention will no doubt occur to those of skill in the art to which the invention pertains. Therefore, it is contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad principles of the invention within the full spirit and scope thereof.