Abstract:
A spring hinge including a pair of hinge leaves having hollow knuckles on adjacent hinges which are arranged in substantially axial alignment such that the hollow knuckles comprise segments of a hinge barrel. A torsion spring made up of a resilient coiled spring member is housed within the hinge barrel. First and second pintles are disposed at opposing ends of the hinge barrel and extend into and between axially aligned knuckles of the hinge leaves. The first and second pintles each engaging the spring member in a locked arrangement such that the spring member extends in a substantially locked relation between the first and second pintles.

Description:
TECHNICAL FIELD 
     This invention relates to a spring hinge, and more particularly to an improved hinge construction incorporating a torsion spring for loading and release during the opening and closure of a door. 
     BACKGROUND OF THE INVENTION 
     Spring hinges for urging a door into a normally closed position following opening are well known. Such automatic door closing devices are particularly useful in maintaining doors in a normally closed position to prevent the doors from being left open following use. The maintenance of such a closed position may be desirable in terms of both security and safety in the environment of use. 
     Spring hinges typically rely upon the loading and subsequent recovery of an internally disposed torsion spring. Due to the fact that individual hinges may be subjected to a variety of conditions so as to require greater or lesser force to achieve closure, it is known to use spring hinge door closing devices which are capable of adjustment to vary the torsional force on the spring and the corresponding force of closure exerted by the spring hinge on the door which it supports. One such prior adjustable spring hinge configuration is illustrated and described in U.S. Pat. No. 4,419,788 to Prout the teachings of which are incorporated herein by reference. 
     The known spring hinge construction described in U.S. Pat. No. 4,419,788 includes a pair of substantially opposed hinge leaves which are rotatable around a common axis defined by hollow knuckle portions which extend along adjacent edges and which are arranged in substantially axial alignment to form a hinge barrel in which a torsion spring is contained. Pintles located in each end of the hinge barrel extend through and between adjacent knuckles and slidingly engage opposing ends of the torsion spring such that the torsion spring is fixed against rotation relative to a knuckle of each respective hinge leaf A pre-loading torsion force may thus be established and adjusted by locking one pintle in place and thereafter rotating the other pintle relative to the first pintle to load the torsion spring. Once adjustment has taken place, a stop pin is inserted through an opening within the wall of the knuckle disposed in alignment with a pin opening in the adjustable pintle thereby holding the adjustable pintle at a predefined rotational position relative to the knuckle. 
     Since adjustment of the torsion spring typically takes place in the field, it is desirable to prevent the adjustable pintle from falling out of the hinge barrel prior to or during such adjustment. In the prior known embodiment, the adjustable pintle has been held in place relative to the hinge barrel by a thrust washer secured around a split bushing and disposed at the intersection between the knuckle elements. This combination of split bushings and a corresponding thrust washer thus provides an anti-friction surface between relatively moving metal parts of the door hinge while simultaneously preventing the pintle surrounded by the bushing and corresponding thrust washer from sliding out of the hinge barrel prior to insertion of an appropriate stop pin during adjustment of the torsion spring. The prior art constructions have thus required a relatively complex arrangement of components including multi-piece anti-friction elements which must be maintained in fixed relation to one another in order to carry out the requisite dual functions of friction reduction and containment of internal elements within the hinge barrel. 
     SUMMARY OF THE INVENTION 
     This invention provides advantages and alternatives over the prior art by providing a spring hinge assembly of substantially reduced complexity which is not dependent upon a multi-piece bushing and thrust washer assembly to hold the end torsion spring in place within the hinge barrel prior to torsion adjustment. More particularly, the present invention provides a spring hinge assembly in which a torsion spring is engageably locked between pintles such that engagement of one of the pintles at a fixed location within the hinge barrel causes the torsion spring and attached pintles to be retained within the hinge barrel thereby preventing inadvertent sliding removal of the pintles and/or the torsion spring prior to final adjustment of the torsion spring. 
     According to one aspect of the present invention a spring hinge is provided including a pair of hinge leaves having hollow knuckles on adjacent hinges which are arranged in substantially axial alignment such that the hollow knuckles comprise segments of a hinge barrel. A torsion spring made up of a resilient coiled spring member is housed within the hinge barrel. First and second pintles are disposed at opposing ends of the hinge barrel and extend into and between axially aligned knuckles of the hinge leaves. The first and second pintles each include a spring acceptance opening engaging the spring member such that the spring member extends in a substantially locked relation between the first and second pintles whereby torsion forces are translated between the torsion spring and the pintles. The pintles are held in place relative to the hinge barrel by pin members such that relative movement of the hinge leaves is translated to the pintles and to the torsion spring. 
     According to one potentially preferred embodiment of the invention a spring hinge is provided including a pair of hinge leaves having hollow knuckles on adjacent hinges arranged in substantially axial alignment such that the hollow knuckles comprise segments of a hinge barrel. A subassembly comprising a resilient torsion spring member of coiled wire with opposing pintles in locked relation at either end is housed within the hinge barrel such that the pintles are disposed at opposing ends of the hinge barrel and extend into and between axially aligned knuckles of the hinge leaves. Preferably, the torsion spring member is held in attached relation between the opposing pintles at the base of a split channel opening extending from the end of each pintle. The split channel opening preferably opens to an increased cross-sectional diameter at the base. The cross-sectional diameter at the base of the split channel opening is preferably slightly larger than the greatest cross-sectional dimension of the coiled wire such that the torsion spring member is not constrictingly pinched while residing at the base. The smaller cross-sectional diameter of the split channel opening below the base permits forced insertion of the wire into the base but substantially prevents manual separation of the spring member from the pintle following such insertion. Pin members hold the pintles in place relative to the hinge barrel such that relative movement of the hinge leaves is translated to the pintles and to the torsion spring. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings which are incorporated in and which constitute a part of this specification, illustrate a potentially preferred embodiment of the present invention 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 a front elevation view of a spring hinge construction according to the present invention; 
     FIG. 2 is a cut-away view of a hinge-barrel portion of a hinge construction according to the present invention; 
     FIG. 3 is an isolated view of a subassembly of the torsion spring and corresponding interlocked pintle members for disposition within the hinge barrel illustrated in FIG. 2; 
     FIG. 4 is an enlarged view of the interlocking relation between the torsion spring and the pintle members as shown in FIG. 3; and 
     FIG. 5 is a horizontal cross-sectional view taken generally along line  5 — 5  in FIG.  1 . 
    
    
     While the invention has been illustrated and generally described above and will hereinafter be described in greater detail in connection with the illustrated and potentially preferred embodiments, it is to be understood that in no event is the invention to be limited to such 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 principles of this invention within the true spirit and scope thereof. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, wherein to the extent possible like elements have been designated by like reference numerals throughout the various views, in FIG. 1 there is illustrated a spring hinge  10  according to the present invention. As illustrated, the spring hinge  10  includes a first hinge leaf  12  and a second hinge leaf  14 . The hinge leaves  12 ,  14  include screw openings  16  for attachment to a door and a door jam in a manner as will be well know to those of skill in the art. The first hinge leaf  12  preferably includes an elongate central hollow knuckle  18  which is disposed between two spaced end knuckles  20 ,  22  extending away from the edge of the second hinge leaf  14 . As illustrated, the central hollow knuckle  18  and the end knuckles  20 ,  22  are arranged in axial alignment so as to form a hollow barrel  24  between the hinge leaves  12 ,  14 . 
     Referring to FIG. 2, it is seen that a pair of opposing pintles  30 ,  32  extend into the hinge barrel  24  so as to span the intersection between the central knuckle  18  and respective end knuckles  20 ,  22 . The pintles  30 ,  32  are preferably of a substantially cylindrical configuration with an outer diameter slightly smaller than the inner diameter of the hinge barrel  24  such that the pintles  30 ,  32  fit in sliding relation within the hinge barrel  24 . 
     As best illustrated in FIG. 3, the first pintle  30  preferably includes a body portion  34  of reduced diameter for insertion within a first substantially sleeve-like friction reducing bushing  40  housed within the lower end knuckle  20  as shown. The first pintle  30  further preferably includes a shoulder stop  50  at which the diameter increases so as to prevent further passage through the first friction reducing bushing  40  such that the shoulder stop  50  rests atop the upper surface of the first friction reducing bushing  40  at a predetermined position along the length of the hinge barrel  24 . The second pintle  32  includes a body portion  36  of substantially straight-sided geometry so as to promote substantially smooth uninterrupted insertion into a second friction reducing bushing  42  seated at the upper portion of the central hollow knuckle  18 . 
     Following insertion, the position of the first pintle  30  within the hinge barrel  24  is preferably maintained by insertion of a static fastening pin  52  (FIG. 2) which is received through an aligned opening  54  in the lower wall portion of the central knuckle  18  (FIG. 1) and enters a radial passageway  56  within the first pintle  30 . As will be appreciated, through use of this fastening technique the first pintle  30  is secured in place in a substantially fixed longitudinal orientation relative to the hinge barrel  24  while nonetheless being rotatable around the central axis of the hinge barrel  24  upon movement of the first hinge leaf  12 . 
     The hinge leaves  12 ,  14  and knuckles  18 ,  20 ,  22  are preferably made of suitable high strength material, such as low carbon steel, stainless steel, brass, or the like. In order to reduce friction between the end knuckles  20 ,  22  and the central knuckle  18 , the first and second friction reducing bushings  40 ,  42  are preferably provided with integral collar portions  44 ,  46  which extend in outward radial fashion between the adjacent knuckles. The body portion of the friction reducing bushings  40 ,  42  is preferably of a substantially straight cylindrical configuration which terminates at a beveled lower edge to facilitate insertion into the central elongate hollow knuckle  18  and the end knuckle  20  in the manner shown. The outer diameter of the friction reducing bushings  40 ,  42  preferably corresponds substantially to the inner diameter of the hinge barrel element into which it is inserted. As shown, the second friction reducing bushing  42  which surrounds the adjustable second pintle  32  is preferably housed within a recess within the upper wall of the central knuckle  18  so as to avoid any undue constriction against the rotation of the adjustable second pintle  32  while nonetheless providing a barrier between opposing metal parts. The friction reducing bushings  40 ,  42  are preferably of a substantially unitary construction formed of a friction induced self-lubricating nylon material or other suitable materials as may be known to those of skill in the art thereby making external lubrication unnecessary. 
     As shown, the pintles  30 ,  32  preferably include projecting finger portions  35 ,  37  for insertion into the interior of a coiled torsion spring  60 . The torsion spring  60  is formed by multiple windings of a spring member  62  of resilient character such as spring steel wire or the like. At each end  64 ,  66  of the torsion spring  60 , the spring member  62  is preferably bent in substantially hook-like fashion so as to extend across the interior of the torsion spring  60 . The ends  64 ,  66  of the torsion spring  60  may thereby be received within slotted grooves  70 ,  72  extending in split relation between the projecting finger portions  35 ,  37 . 
     The projecting finger portions  35 ,  37  are preferably formed by cutting the slotted grooves  70 ,  72  into a substantially cylindrical portion of reduced diameter extending from the ends of the pintles  30 ,  32 . The slotted grooves  70 ,  72  preferably have a width such that the ends  64 ,  66  of the torsion spring  60  may be force fit into the slotted grooves  70 ,  72  resulting in cross-sectional compression until reaching a corresponding base portion  74 ,  76  of increased diameter. The ends  64 ,  66  of the torsion spring  60  may thereby be inserted in a substantially snap fit relation into the slotted grooves  70 ,  72  and held in place at the base portions  74 ,  76 . As illustrated, the diameter of the base portions  74 ,  76  is preferably slightly greater than the accepted ends  64 ,  66  of the spring member  62  such that the ends  64 ,  66  are not constrictingly pinched once insertion is completed. At the same time, the reduced width of the slotted grooves  70 ,  72  serves to prevent the withdrawal of the ends  64 ,  66  absent the exertion of substantial force. It is believed that the absence of substantial constriction of the spring member  62  at the base portions  74 ,  76  permits the ends  64 ,  66  to move within the base portions  74   76  as necessary to maintain the torsion spring  60  in a substantially axial relation upon the application of a torsion force. Maintenance of such an axial orientation is believed to aid in the avoidance of non-axial kinking in the torsion spring upon application of torque thereby avoiding undue stress concentration which may result in premature damage to the torsion spring. 
     As previously indicated, the first pintle  30  is preferably held at a substantially fixed position by the static fastening pin  52 . Due to the locking relation between the torsion spring  60  and the pintles  30 ,  32 , once the first pintle  30  is secured in place, the attached torsion spring  60  and second pintle  32  are likewise secured against sliding withdrawal from the hinge barrel  24 . The second pintle  32  nonetheless remains rotatable within the hinge barrel  24  so as to permit ready adjustment of the torsional force of the attached torsion spring  60 . 
     As best illustrated through simultaneous reference to FIGS. 1 and 5, the end knuckle  22  which surrounds the first pintle  30  is preferably provided with an elongate horizontal slot  80  which extends about the circumference of the end knuckle  22  so as to expose radial passageways  82  within the second pintle  32 . As shown, the second pintle  32  is preferably provided with a multiplicity of such radial passageways  82  spaced about the circumference of the pintle which become sequentially aligned with the horizontal slot  80  during rotation of the pintle  30  to expose them for insertion of a loose stop pin  84 . The length of the horizontal slot  80  is preferably sufficient to expose three or more radial passageway openings simultaneously such that the pintle  30  may be easily moved by use of a small metal rod or the like inserted into one of the exposed passageway openings  82  and moved along the slot to rotate the pintle in a desired direction and thereby vary the initial torsional force of the torsion spring  60 . As will be appreciated, the ability to adjust the torsional force of the torsion spring  60  arises due to the fact that the torsion spring  60  is secured at one end to the previously fixed first pintle  30  which is held in a substantially static position. Thus, rotational adjustment of the second pintle  32  causes a loading of the torsion spring  60 . When the desired load has been applied to the torsion spring  60 , the loose stop pin  84  is inserted into a passageway opening of the second pintle  32  to lock the second pintle  32  and the torsion spring  60  against counter rotation relative to the end knuckle  22  and the second hinge leaf  14 . 
     The improved spring hinge construction of the present invention may be easily manufactured and assembled from a relatively small number of component parts in comparison to prior hinge constructions. To assemble the spring hinge  10 , the knuckles  18 ,  20 ,  22  are axially aligned in the manner as illustrated in FIGS. 1 and 2 with the friction reducing bushings  40 ,  42  in place such that the collar portions  44 ,  46  extend between the opposing knuckle components. The torsion spring  60  and pre-attached pintles  30 ,  32  are inserted as a single unit subassembly into the hinge barrel  24  formed by the knuckles  18 ,  20 ,  22 . Insertion is terminated when the shoulder stop  50  of the first pintle  30  comes to rest atop the radially projecting collar portion  44  of the first friction reducing bushing  40  thereby establishing a predefined position for the torsion spring  60  and attached pintles  30 ,  32  within the hinge barrel  24 . The static fastening pin  52  is press fit into the aligned opening  54  of the knuckle  18  so as to reside in locking relation within the radial passageway  56  of the first pintle  30 . No additional assembly is required except that upon installation of the spring hinge  10  in the field, the user may adjust the torsion by rotation of the second pintle  32  and insertion of the loose stop pin  84 . 
     It is, of course, to be understood that a wide range of alternatives and modifications to the embodiment of the present invention as set forth above may exist. Thus, while the present invention has been illustrated and described in relation to potentially preferred embodiments, procedures and practices, it is to be understood that such embodiments, procedures and practices 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 present invention may occur to those of skill in the art. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad principles of the present invention within the full spirit and scope thereof.