Abstract:
A snap-on terminal clip for installation onto the end of the spiral rod of a spiral rod window balance. The upper region of the terminal clip lockingly engages a locking pin secured to the external end of the spiral rod. The lower region of the clip terminates in a substantially hook shaped segment that engages the ledge of a window sash, thereby supporting the sash as it moves vertically through the jamb channel of the window assembly.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention pertains to the field of window balances. Particularly, the invention pertains to a clip attached to the exposed rod end of a spiral rod balance. The clip then connects the spiral balance to a window sash by snapping over a pin secured to the end of the spiral rod. 
       BACKGROUND OF THE INVENTION 
       [0002]    Window assemblies may include a single sash or two sashes, which are referred to, respectively, as single hung or double hung windows. A window assembly generally includes a window frame, at least one sash, a pair of opposing window jambs, each jamb having a channel for allowing the vertical travel of each sash, and at least one window balance to assist with the raising and lowering of the sash to which it is attached by counterbalancing the weight of the sash. 
         [0003]    Springs are utilized to provide the counterbalance force. In spiral rod balances, a torsion spring provides a substantially constant lifting force over the full travel of the sash through the jamb channel. The torsional spring force is converted into a lifting force by an elongated spiral rod. The torsion spring and elongated spiral rod are all housed within a containment tube which protects the moving parts of the balance from contamination. The containment tube has an open end and a closed end. The closed end of the containment tube is secured to the jamb channel, for example, by a bolt, screw, rivet or other fastener, depending on the design preferences of the window manufacturer. The open end of the containment tube is capped by a rotatable coupling having a center slot through which the elongated spiral rod travels. When the spiral rod protruding from the open end of the containment tube is attached to a window sash, depending on the direction of vertical movement required to open the window, the spiral rod is either extended or retracted. For example, in a double hung window design the upper sash moves downward to open the window and the lower sash moves upward to open the window. 
         [0004]    In pivoting window sashes, the spiral rod connects to a shoe or carrier which traverses up and down the jamb channel of the window assembly. The window sash and window balance are linked together through the shoe/carrier by means of a pivot bar which extends from an end of each stile of the sash. 
         [0005]    Alternatively, the end of the spiral rod may attach directly to the sash itself. In this case, a clip is securely attached to the end of the spiral rod. The conventional means of attaching the clip to the spiral rod consists of the use of a rivet. Whether the spiral rod balance is attached to a shoe or to the sash requires a different configuration of the spiral rod. In the instance where the spiral rod balance is attached to the shoe, only a pin is required at the end of the rod. However, if the spiral rod balance is to be attached to the sash, the clip needs to be securely fitted to the end of the rod. Since window manufacturers utilize both designs, the balance manufacturer must inventory two different spiral rods, even though the remainder of the balance components are the same. It is desirable, therefore, to have a single spiral rod that can be readily adapted for use with either spiral rod balance assembly. What is needed is a terminal clip that can be easily installed onto the end of a universal pinned spiral rod without the need for a riveting operation as is now conventionally done. 
       SUMMARY OF THE INVENTION 
       [0006]    The present device is a terminal clip and a method for its installation onto the end of the spiral rod of a spiral rod window balance. The terminal clip uses the spring like memory of the material used to make the terminal clip to snap over a locking pin secured to the exposed end of the spiral rod. 
         [0007]    The method of installing the terminal clip onto a spiral rod includes the steps of first orienting the snap element of the terminal clip in the direction of the locking pin in the spiral rod. The snap element of the terminal clip then slides over the locking pin, snapping the terminal clip semi-permanently onto the spiral rod. If necessary, the terminal clip may be removed from the spiral rod by forcibly disengaging the snap element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0008]      FIG. 1A  shows a perspective view of a first embodiment of the terminal clip of the invention. 
           [0009]      FIG. 1B  shows a plan view of the terminal clip of  FIG. 1A  from the top of the clip. 
           [0010]      FIG. 2  shows the terminal clip of  FIG. 1A  being oriented to hook onto the end of the spiral rod of a spiral rod balance. 
           [0011]      FIG. 3  shows the initial engagement of the terminal clip of  FIG. 2  with the locking pin at the end of the spiral rod. 
           [0012]      FIG. 4  shows another view of the initial engagement step of  FIG. 3 . 
           [0013]      FIG. 5  shows the rotation of the first embodiment of the terminal clip as it pivots around the locking pin at the end of the spiral rod. 
           [0014]      FIG. 6  shows one perspective view of the terminal clip of  FIG. 5  locked onto the end of the spiral rod. 
           [0015]      FIG. 7  shows another perspective view of the terminal clip of  FIG. 6  locked onto the end of the spiral rod. 
           [0016]      FIG. 8A  shows a cut out of a window sash to which the first embodiment of the terminal clip is attached. 
           [0017]      FIG. 8B  shows a close up view of  FIG. 8A . 
           [0018]      FIG. 9A  shows an exposed detail of a spiral balance within the jamb channel of a window assembly in which the first embodiment terminal clip is locked in place onto the end of the spiral rod. 
           [0019]      FIG. 9B  shows a close up of  FIG. 9A . 
           [0020]      FIG. 10A  shows a second embodiment of the terminal clip. 
           [0021]      FIG. 10B  shows the terminal clip of  FIG. 10A  in the initial stages of installation around the locking pin of a spiral rod. 
           [0022]      FIG. 10C  shows the terminal clip of  FIGS. 10A and 10B  snapped around the locking pin in semi-permanent engagement with the spiral rod. 
           [0023]      FIG. 10D  shows an isometric view of the second embodiment of the terminal clip fully installed on the end of the spiral rod. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]      FIGS. 1A through 9B  pertain to a first embodiment of the snap-on terminal clip of the invention.  FIGS. 1A and 1B  show the first embodiment of the snap-on terminal clip  10  which consists of a primary structural support  12  linked to a rear wall  14  by an integral “U” shaped linkage  16  proximate a first end region  18  of the terminal clip  10 . The rear wall  14  is shorter than the primary structural support  12  and is disposed proximate the first end region  18 . The rear wall  14  and the primary structural support  12  are substantially coplanar and are separated from each other by a distance “D1” which is approximately equal to the thickness of the spiral rod  22  of a conventional spiral rod window balance  20  (see  FIGS. 2 and 3 ). Located proximate the end  15  of the rear wall  14  is a first upset locking tab  17 . The function of the first locking tab  17  will be explained later. 
         [0025]    A second end region  24  of the terminal clip  10  is integrally connected to the primary structural support  12  by a linking platform  26 . The plane of the primary structural support  12  is disposed approximately 90 degrees from the plane of the linking platform  26 . Linking platform  26  terminates in a sash interface region  28 . The sash interface region  28  consists of an inner wall segment  30  and an outer wall segment  32  which are substantially coplanar with each other. The inner wall segment  30  is integrally joined to the outer wall segment  32  by a substantially “U” shaped segment  34 . The distance “D2” between the outer wall segment and the inner wall segment is substantially equal to the thickness of a retaining ledge  36  on window sash  38  (see  FIGS. 8A and 8B ). The outer wall segment  32  may have an optional second upset tab  40  which may either fit into a mating slot on the surface of the retaining ledge  36  (not shown) or may simply provide an interference fit with the surface of the retaining ledge  36  to help secure the sash  38  within the walls  30  and  32  of the sash interface region  28 . 
         [0026]    The terminal clip  10  may be made from a variety of materials so long as it is able to provide the necessary strength to support the weight of the sash. It is also preferable that the material chosen have some degree of structural memory in order for the wall segments  30  and  32  to flex slightly away from each other as the terminal clip  10  is first connected to the retaining ledge  36  of the sash  38  and then substantially return to their resting position to provide an interference fit to insure the continuous retention of the sash  38  within the terminal clip  10 . Suitable materials include formed sheet metal, die cast metal or molded plastics and resins, such as Nylon 66. 
         [0027]    The primary structural support  12  has a hole  42  that is located in a portion of the surface of the primary structural support  12  that is not adjacent the rear wall  14 . Referring to  FIGS. 2 through 7 , the method of installing the terminal clip  10  to the spiral rod window balance  20  is shown. A conventional spiral rod balance  20  contains a spiral rod  22 . In operation, the spiral rod  22  is pulled from the containment tube  21  as the sash is moved either up or down away from its resting position. The torsion spring (not shown) within the containment tube  21  is fixed at the top end of the containment tube where its free end can wind and unwind within the containment tube  21  by means of being attached to the rotatable coupling located at the bottom of the containment tube  21 . The spiral rod  22  is constrained within the torsion spring which is within the containment tube  21  and as the rod is pulled out of the spiral balance  20  through the center slot of the coupling, the coupling rotates with respect to the containment tube  21  and gradually tightens the torsion spring, thus providing the incremental increase in resistance to counter the weight of the sash and assist in the vertical movement of the sash through the jamb channel of the window frame. The terminal clip  10  prevents the rotation of the external end  23  of the spiral rod  22  relative to the sash  38  by securing the spiral rod  22  to the retaining ledge  36  of the sash  38 . 
         [0028]    To assemble the terminal clip  10  to the spiral balance  20 , hole  42  of the terminal clip is first aligned with one of the locking pins  44  securely fixed to the external end  23  of the spiral rod  20  with the rear wall  14  facing the spiral rod, as shown in  FIG. 2 . As shown in  FIG. 3 , one of the locking pins  44  is inserted through hole  42  (see  FIG. 4 , also). Once the hole  42  and locking pin  44  are connected, the terminal clip  10  is rotated about the axis of the locking pin  44  so that the spiral rod  22  is captured between the primary structural support  12  and the rear wall  14 . The beginning of the rotation movement of the terminal clip is best seen in  FIG. 5 . Once the spiral rod  20  is completely encapsulated within the gap between the rear wall  14  and the primary support structure  12 , the first locking tab  17  snaps around the edge  25  of the spiral rod  22 , thereby securely locking the terminal clip  10  to the spiral rod, as shown in  FIGS. 6 and 7 . The attachment of the terminal clip  10  to a spiral rod balance  20 , converts what is traditionally called a pinned balance to a flexure “clip-on” rod end balance. This is because the balance does not require an adapter to attach it to the sash. The “U” shaped sash interface region  28  of the terminal clip  10  provides a simple yet effective means for securing the balance to the sash. 
         [0029]    Referring to  FIGS. 8A and 8B , a spiral rod balance  20  is shown installed within the jamb channel  50  of a window frame. Retaining ledge  36  of sash  38  is shown as being secured within the sash interface region  28  of terminal clip  10 . A breakaway view of the clip-on rod end balance installed within a jamb channel is shown in  FIGS. 9A and 9B . The retention of the terminal clip  10  to the retaining ledge  36  of the sash  38  enables the balance to assist with the vertical movement of the sash through its vertical travel within the jamb channel. 
         [0030]    A second embodiment of the snap-on terminal clip is shown in  FIGS. 10A-10D . Referring to the side views of  FIGS. 10B and 10C , the “S” shaped configuration of the second embodiment snap-on terminal clip  200  is best observed. The snap-on terminal clip  200  consists of a spiral rod interface region  202  and a sash interface region  204 . The spiral rod interface region  202  consists of two parallel flexible hook segments  206   a  and  206   b.  The flexible hook segments are separated by a channel  208 . The width of channel  208  approximates the thickness of the spiral rod  20 . Each flexible hook segment  206   a  and  206   b  has a main structural support region  210   a  and  210   b,  respectively. Each structural support region extends in a circular path, when viewed from the side, traversing in a more than 180 degree angle relative to the plane of its respective structural support region to terminate in ends  212   a  and  212   b,  respectively. The ends  212   a  and  212   b  are flared out away from their respective main structural support regions to facilitate engagement with locking pins  44 . The diameter formed by the circular path of the flexible hook segments  206   a  and  206   b  approximates the outer diameter of the locking pins  44  of the spiral rod  22 . The distance between the terminal ends  212   a  and  212   b  and their respective main structural support regions  210   a  and  210   b  is less than the diameter of the locking pins  44 , so that after engagement between the snap-on terminal clip  200  and one of the locking pins  44 , the snap-on terminal clip is semi-permanently engaged on the locking pin  44 . As with the first embodiment of the snap-on terminal clip  10 , the material from which the second embodiment of the snap-on terminal clip is made includes formed sheet metal, die cast metal, molded plastics and resins, such as Nylon 66. One of the requirements for the choice of materials is that it has a structural memory that allows it to flex when needed and yet return substantially to its original form after flexure. 
         [0031]    Referring to  FIG. 10B , the snap-on terminal clip  200  is shown as it begins to be snapped over the locking pin  44  of the spiral rod  20 . The channel  208  is lined up with an edge  25  of the spiral rod  22 . The terminal ends  212   a  and  212   b  are forced to flex around the diameter of the locking pin  44 . In  FIG. 10C , the terminal ends  212   a  and  212   b  have passed beyond the locking pin  44 , thus snapping the snap-on terminal clip  200  semi-permanently over the locking pin  44 . Note that with respect to the second embodiment of the snap-on terminal clip  200 , the snap-on terminal clip is allowed to rotate to some degree around the axis of the locking pin  44 . This feature is helpful when the time comes to engage the sash engagement region  204  with a window sash  36  (please refer to  FIGS. 8A and 8B  for a view of the sash).  FIG. 10D  is an isometric view of the second embodiment of the snap-on terminal clip  200  secured to the end of the spiral rod  20  of a spiral rod balance  20 . The snap-on terminal clip  200  may be disengaged from the spiral rod by forcibly separating the terminal ends  212   a  and  212   b  from their structural support regions  210   a  and  210   b  and sliding the snap-on terminal clip  200  off of the locking pin  44 . 
         [0032]    Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.