Abstract:
A self-returning hinge assembly utilizing a spring disposed along a linearly displaceable guide shaft element mounted through a polymeric guide plate disposed in substantial alignment with an aperture supporting an elongated proximal portion of the guide shaft. Upon displacement of the door from a pre-established set point, the spring is compressed thereby generating a biasing force along the guide shaft to bring the door back to the pre-established set point. The linear travel path of the guide shaft element is maintained by the guide plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This non-provisional application claims the benefit of, and priority from U.S. provisional application 61/827,699 filed May 27, 2013. The contents of such prior application and all documents referenced herein are hereby incorporated by reference in their entirety as if fully set forth herein. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a self-returning hinge assembly mounted between a support floor and a door. More particularly, the disclosure relates to a self-returning hinge assembly mounted between a support floor and a door utilizing a spring disposed along a linearly displaceable guide shaft element mounted through a supporting guide plate. Upon displacement of the door from a pre-established set point, the spring is compressed thereby generating a biasing force along the guide shaft to bring the door back to the pre-established set point. The linear travel path of the guide shaft element is maintained by the guide plate. 
     BACKGROUND 
     Floor hinges are well known. As will be appreciated by those of skill in the art, such hinges typically use a base plate assembly that is bolted or otherwise mounted to the floor so as to remain substantially static. Such hinges also typically include a displaceable frame structure mounted to the door and operatively connected to the base plate assembly. Thus, when the door is moved, there is a relative movement between the frame structure and the base plate assembly. Self returning floor hinges using a spring biased return are also well known. One exemplary spring biased floor hinge is the Model 7811 spring pivot marketed by Bommer Industries, Inc. having a place of business in Landrum, S.C. Such spring biased floor hinges incorporate a spring disposed along a linearly displaceable guide shaft element mounted within the displaceable frame structure. Upon displacement of the door from a pre-established set point, a cam-follower attached to the guide shaft is displaced thereby moving the guide shaft in a linear manner and compressing the spring. The spring compression generates a biasing force along the guide shaft to bring the door back to the pre-established set point. In such prior floor hinges, the linear travel of the guide shaft is maintained by alignment pins extending transverse to the guide shaft and projecting through guide slots in plates above and below the guide shaft. By constraining the pins within the guide slots, the operatively connected guide shaft is thereby limited to substantially linear travel in line with the guide slots as the cam follower is displaced. 
     Another exemplary spring biased floor hinge is illustrated and described in US patent application 2008/0127452A1 (incorporated by reference). This construction replaces the alignment pins of the Model 7811 with a generally “H” shaped guide plate of hardened steel or the like with a central aperture supporting the guide shaft. 
     While the prior constructions of self returning floor hinges have performed quite well, the prior products incorporate metal guide plates or pin elements and guide slots to maintain consistent repeatable linear travel. Due to the large number of use cycles that these parts experience, the practice has been to use components of substantial cross-sectional dimension in combination with a relatively heavy cam follower body. Moreover, it has been found that over extended periods of time, the guide slots may tend to experience a degree of wear that varies over the length of the guide slots. This variable wear may give rise to a noticeable clicking sound over the life of the product. Moreover, the use of an “H” shaped guide plate of hardened steel or the like may be difficult to maintain in proper alignment and may impart enhanced wear to a guide shaft during prolonged use. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure provides advantages and alternatives over the prior art by providing a self-returning hinge assembly mounted between a support floor and a door utilizing a spring disposed along a linearly displaceable guide shaft element mounted through a polymeric guide plate disposed in substantial alignment with an aperture supporting an elongated proximal portion of the guide shaft. Upon displacement of the door from a pre-established set point, the spring is compressed thereby generating a biasing force along the guide shaft to bring the door back to the pre-established set point. The linear travel path of the guide shaft element is maintained by the guide plate. The guide plate may be mounted at two opposing points on a surrounding frame and bushings may be present at either end of the spring for disposition in sandwich relation between the spring and the guide shaft element. 
     In accordance with one exemplary aspect, the present disclosure provides a self returning floor mounted hinge assembly for a door. The hinge assembly includes a base plate adapted for stationary mounting to a floor or other support structure and a bearing cam assembly secured in substantially fixed relation to the base plate. The bearing cam assembly includes a pair of spaced apart roller elements. A frame structure including an upper bracket and a lower bracket is adapted to be mounted to the door in rotatable relation to the bearing cam assembly. The hinge assembly further includes a guide shaft having a proximal end projecting away from the bearing cam assembly. The proximal end is supported in sliding relation within a shaft opening in the frame structure. The guide shaft further includes a distal end of reduced diameter relative to the proximal end. The distal end projects towards the bearing cam assembly and is operatively connected to a cam follower thrust lug having an angled face operatively engaging the roller elements. A coil spring is disposed in surrounding relation to the guide shaft such that the guide shaft is slideable through the coil spring. A collar is held in fixed relation relative to the guide shaft at a position between the thrust lug and the coil spring. A first polymeric bushing and a second polymeric bushing are disposed in surrounding relation to the guide shaft at opposing ends of the coil spring. The first polymeric bushing and the second polymeric bushing each have a nipple segment disposed in sandwiched relation between the coil spring and the exterior of the guide shaft. The first polymeric bushing includes a first platform segment disposed between the collar and the coil spring in opposing, contacting relation to a first end of the coil spring and the second polymeric bushing includes a second platform segment disposed between the shaft opening and the coil spring in opposing, contacting relation to a second end of the coil spring such that the coil spring is held between the first platform segment and the second platform segment. Upon axial movement of the guide shaft away from the bearing cam assembly, the coil spring is compressed between the first platform segment and the second platform segment. A polymeric guide plate is held in inserted relation between the upper bracket and the lower bracket at a position between the collar and the cam follower thrust lug such that the guide shaft is supported in sliding relation by the guide plate. The guide plate includes a plate body surrounding an acceptance opening axially aligned with the shaft opening in the frame structure and adapted to slidingly support the guide shaft. The guide plate further includes a pair of opposing perimeter ears adapted for insertion through enclosed slots in the upper and lower brackets such that the guide plate is supported at two opposing points. 
     It is to be understood that other aspects, advantages, and features of the disclosure will become apparent through a reading of the following detailed description of the disclosure and/or through use of the described embodiments. Accordingly, such description is to be understood to be exemplary and explanatory only and in no event is the disclosure to be limited to any illustrated and described embodiments. On the contrary, it is intended that the present disclosure shall extend to all alternatives and modifications as may embrace the principals of this disclosure within the true spirit and scope thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure 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 given above, and the detailed description set forth below, serve to explain the principles of the disclosure wherein: 
         FIG. 1  is a schematic perspective view of a floor hinge consistent with the present disclosure; 
         FIG. 2  is a side view of the floor hinge of  FIG. 1 ; 
         FIG. 3  is a sectional view of a floor hinge of  FIG. 1  taken generally along line  3 - 3  in  FIG. 2 ; 
         FIG. 4  is a schematic perspective view of a lower frame member used in the floor hinge of  FIG. 1 ; 
         FIG. 5  is a schematic perspective view of an upper frame member used in the floor hinge of  FIG. 1 ; 
         FIG. 6  is a schematic perspective view of an exemplary guide plate used in the floor hinge of  FIG. 1 ; 
         FIG. 7  is a schematic perspective view of an exemplary guide shaft used in the floor hinge of  FIG. 1 ; 
         FIG. 8  is a schematic perspective view of an exemplary polymeric bushing used in the floor hinge of  FIG. 1 ; and 
         FIG. 9  is a schematic perspective view of an exemplary thrust lug used in the floor hinge of  FIG. 1 . 
     
    
    
     Before the exemplary embodiments are explained in detail, it is to be understood that the invention is in no way limited in its application or construction to the details and the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for purposes of description only and should not be regarded as limiting. The use herein of terms such as “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. 
     DETAILED DESCRIPTION 
     Reference will now be made to the drawings, wherein, to the extent possible, like elements are designated by like reference numerals in the various views. Referring now to  FIG. 1 , an exemplary hinge assembly  10  is illustrated. As shown, the hinge assembly  10  utilizes a base plate  12  which may be mounted in substantially fixed relation to the floor or other support surface. A bearing race  16  is secured to the base plate  12  and houses a bearing (not shown) such as a nylon ring bearing or the like. The base plate  12  and the bearing race  16  are adapted to accept and retain a key post projecting downwardly from a bearing cam assembly  22  in a manner as will be well known to those of skill in the art such that the bearing cam assembly  22  is held in substantially fixed relation relative to the base plate  12 . Thus, the bearing cam assembly is held stationary relative to the floor or other support surface. 
     In the illustrated construction, the hinge assembly  10  includes a frame structure formed from a first or lower bracket  26  ( FIG. 4 ) and a second or upper bracket  28  ( FIG. 5 ). As best seen in  FIG. 4 , the lower bracket  26  includes a lower bracket opening  30  sized to accept the key post projecting downwardly from the bearing cam assembly  22  without obstruction. The upper bracket  28  likewise includes an upper bracket opening  32  sized to accept a pin  34  projecting upwardly from the bearing cam assembly  22 . 
     As will be readily appreciated by those of skill in the art, when the bearing cam assembly  22  is fixed in position relative to the base plate  12 , the upper and lower brackets may rotate around the bearing cam assembly  22  with an axis of rotation disposed in coaxial relation to the pin  34 . As shown in  FIG. 2 , the upper and lower brackets  26 ,  28  may be mounted in substantially fixed relation at a lower inner corner of a door  40  by screws, bolts or other appropriate fixation devices. Thus, as the door  40  is rotated, the upper and lower brackets  26 ,  28  move in concert with the door  40  while the bearing cam assembly  22  remains held in place by the base plate  12 . 
     As shown, the bearing cam assembly  22  preferably includes a pair of low friction rollers  42  of nylon or other polymeric material incorporating a wear activated lubricant such as graphite or the like as will be known to those of skill in the art. The rollers  42  are held in place by roller pins  44  on opposite sides of the axis defined by the pin  34  such that they are substantially free to rotate. In the assembled state, the rollers  42  engage a cam follower thrust lug  46  which is preferably formed from the same material as the rollers  42  so as to minimize friction. According to one exemplary construction, the thrust lug  46  may be substantially trapezoidal in shape and may incorporate a centrally disposed scalloped face depression  48  extending along the full height of the thrust lug at a roller engagement face  49  adapted to engage the rollers  42 . 
     In the illustrated exemplary construction, the thrust lug  46  is affixed at a distal end of a guide shaft  50  of carburized steel or like structural material ( FIG. 7 ). As best illustrated through reference to  FIGS. 3 and 7 , the guide shaft  50  may incorporate a stepped construction including a main body portion  51  which steps down to an adjacent reduced diameter intermediate segment  52  of reduced diameter. The intermediate segment  52 , in turn, steps down to a nipple segment  53  of reduced diameter relative to the intermediate segment. As best understood through joint reference to  FIGS. 3 ,  7  and  9 , the nipple segment  53  may be held by press-fit insertion within a lug opening  54  at the rear face of the thrust lug  46  facing away from the roller engagement face  49 . In this assembled condition, the rear face may abut a substantially flat step  56  at the intersection between the intermediate segment  52  and the distal nipple segment  53 . According to one exemplary practice, the compression force of the thrust lug  46  may hold the distal nipple segment  53  in place without additional joining mechanisms. As illustrated, the exemplary guide shaft  50  may further include a threaded segment  55  disposed along the main body portion  51  in adjacent relation to the intermediate segment  52 . 
     As best seen in  FIGS. 1-3 , the proximal end of the guide shaft  50  opposing the thrust lug  46  may be held within a shaft opening  62  in an upwardly extending leg portion of the lower bracket  26 . A coil spring  66  is disposed in surrounding relation to the main body portion  51  of the guide shaft  50  such that the guide shaft  50  may slide freely within the coil spring  66 . In the assembled state, the coil spring  66  is held in compression in the region between an adjustable collar  70  and the upwardly extending leg portion of the lower bracket  26 . In the illustrated exemplary construction, tensioning adjustments may be made by simply changing the position of collar  70  along the guide shaft  50  using engagement between the collar  70  and the threaded segment  55  whereby the collar  70  may be advanced to variable positions along the threaded segment. Once the tensioning set point is fixed, axial stroke movement of the guide shaft  50  through the coil spring  66  and the shaft opening  62  further compresses the coil spring  66  and generates a return biasing force as the spring seeks to relieve the increased applied compression. 
     In the illustrated exemplary construction, the guide shaft  50  is supported in sliding relation at its distal end by a polymeric guide plate  74  of nylon or like material. If desired, the guide plate  74  may be infused with a wear-activated lubricant such as graphite or the like to reduce friction. As illustrated, the guide plate  74  surrounds the reduced diameter intermediate segment  52  of the guide shaft  50  at a position between the thrust lug  46  and the collar  70 . 
     As best seen in  FIG. 6 , in the exemplary construction, the guide plate  74  is of unitary construction with substantially uniform thickness incorporating a rectangular plate body  76  with a pair of outwardly projecting rectangular perimeter ears  78  extending away from opposing sides of the plate body  76  in substantially mirror image relation to one another. Thus, the plate body  76  and the perimeter ears  78  cooperatively define a cross-shaped perimeter. An acceptance opening  80  is disposed substantially centrally within the plate body  76 . The acceptance opening  80  within the guide plate  74  is preferably sized so as to permit the intermediate segment  52  of the guide shaft to slide freely through the opening while maintaining a close fitted relation thereby holding the shaft substantially straight during axial movement. Thus, the guide shaft  50  is supported between the upwardly extending leg of the lower bracket  26  and the guide plate  74 . 
     As best seen through joint reference to  FIGS. 4-6 , the lower bracket  26  and the upper bracket  28  each incorporate an enclosed ear acceptance slot  82 , extending partially across the width dimensions of the respective brackets. As seen in  FIG. 1 , the ear acceptance slots  82  are each adapted to receive and retain a perimeter ear  78  of the guide plate  74  in sliding fit relation. This engagement between the perimeter ears  78  and the upper and lower brackets  26 ,  28  is used to secure the guide plate  74  in place using only the engagement provided by the perimeter ears at the interior of the brackets. Surprisingly, it has been found that the illustrated two point engagement in combination with the polymeric guide plate provides a secure and durable connection for the guide plate  74  while also providing adequate support for the guide shaft. 
     Referring now to  FIGS. 2 ,  3  and  8 , it may be seen that in the illustrated exemplary construction a pair of bushings  90  are disposed along the guide shaft  50  adjacent either end of the coil spring  66 . The bushings  90  may be formed from a polymeric material such as nylon or the like. If desired, the bushings may be infused with a wear activated lubricant such as graphite or the like to reduce friction. As best seen in  FIG. 8 , each of the bushings may be of generally annular configuration incorporating a generally disk-shaped platform  92  and a reduced diameter nipple  94  extending downwardly from the platform  92  in substantially coaxial relation to the platform. A substantially uniform diameter through channel  95  extends through the bushings  90 , such that the bushings are hollow along their length. As best seen in  FIG. 2 , in the exemplary construction, the bushings  90  extend in sleeve-fitting relation about the guide shaft  50  such that at each end of the coil spring  66 , a nipple  94  of a bushing is disposed in sandwiched relation between the inner surface of the coil spring  66  and the outer surface of the main body portion  51  of the guide shaft  50 . In this condition, a platform segment  92  of a bushing  90  abuts against each end of the coil spring  66 . Accordingly, a first one of the bushings  90  defines a barrier between a first end of the coil spring  66  and the collar  70  and a second one of the bushings  90  defines a barrier between a second end of the coil spring  66  and the upwardly extending leg of the lower bracket  26 . Nonetheless, the guide shaft  50  is able to slide axially within the through channels  95  in the bushings  90  substantially without restriction. 
     As best seen in  FIG. 1 , a bushing  90  as shown in  FIG. 8  may also be disposed in the upper bracket opening  32  in surrounding relation to the pin  34  projecting upwardly from the bearing cam assembly  22 . As will be appreciated, this arrangement reduces friction and wear between the pin  34  and the upper bracket  28 . 
     As noted previously, during operation the bearing cam assembly  22  is held in fixed relation by its connection to the base plate  12  while the frame structure with the attached guide shaft  50 , thrust lug  46 , coil spring  66  and guide plate  74  move with the door  40 . As the door  40  is opened, the face  49  of the thrust lug  46  rides over the surface of the rollers  42 . As surfaces of the thrust lug outboard of the face depression  48  ride over a contacting roller  42 , the thrust lug and attached guide shaft  50  are progressively pushed away from the bearing cam assembly  22 . This action translates to axial movement of attached guide shaft  50  in a path defined by the axis running between the acceptance opening  80  in the guide plate  74  and shaft opening  62  in the upwardly extending leg portion of the lower bracket  26 . The axial movement away from the bearing cam assembly  22  in turn causes compression of the coil spring  66  between the two opposing bushings  90 . In the illustrated construction incorporating a face depression  48  at a central portion of the thrust lug, continued rotation eventually causes the point of contact between the thrust lug and the roller to move into the zone occupied by the face depression  48  such that the roller drops into the depression. With the roller  42  disposed within the face depression  48 , the door  40  will remain ajar until a return rotational force is applied by an operator forcing the roller back onto the sloped face. Thus, the illustrated construction permits the door to be moved through a substantial angle with self biasing return over the interior portion of the angle and with the ability to hold the door open at the angle extremes. Of course, the use of a face depression on the thrust lug is optional. By way of example only, in the event that a face depression is not utilized, the thrust lug may simply use a face which tapers to an apex at the center. As will be appreciated, in such a construction the hinge will be self returning over substantially its full range of motion. 
     Regardless of the thrust lug construction which may be utilized, it has been found that the utilization of a polymeric guide plate  74  with a cross-shaped perimeter in combination with bushings  90  disposed between the coil spring  66  and the guide shaft  50  provides excellent support and wear resistance over a large number of cycles. In particular, such a construction has been tested to over 2 million cycles without failure thereby reflecting significant improvements over prior known constructions despite the use of a cross-shaped polymeric guide plate which would be expected to degrade and lose support more rapidly than prior metal support structures. 
     Of course, variations and modifications of the foregoing are within the scope of the present disclosure. Thus, it is to be understood that the disclosure disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present disclosure.