Patent Publication Number: US-2021164278-A1

Title: Inverted constant force window balance for tilt sash

Description:
PRIORITY CLAIM 
     This application is a continuation of U.S. patent application Ser. No. 14/744,940, filed Jun. 19, 2015, which is a continuation of U.S. patent application Ser. No. 13/081,089, filed Apr. 6, 2011, now U.S. Pat. No. 9,133,656, which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/321,340, filed on Apr. 6, 2010, the disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     This application relates to window sash balances and, more particularly, to inverted constant force window balance systems for tilt sashes. 
     BACKGROUND OF THE INVENTION 
     Inverted constant force window balance systems are depicted in, for example, U.S. Pat. Nos. 5,353,548 and 5,463,793, the disclosures of which are hereby incorporated by reference herein in their entireties. Inverted constant force window balances utilize a housing or shoe that carries a coil spring having a free end secured to a window jamb channel with a mounting bracket, screw, or other element. As the coil spring unwinds, the recoil tendency of the spring produces an upward force to counter the weight of the window sash. The shoe may be a tilt-in shoe that allows the window sash to tilt inwards for cleaning and/or installation/removal purposes. As the window sash tilts, a locking mechanism holds the shoe in place to prevent the coil spring from retracting the shoe in the absence of the weight of the sash. 
     Existing tilt-in inverted constant force window balances, however, suffer from several shortcomings. First, as with many types of balance shoes, the locking shoes used with inverted constant force window balances are dimensioned such that they can not easily be inserted into the window jamb channel. Second, particularly heavy window sashes may require more than a single spring on each side to provide an adequate counterbalance. While it is possible to add additional springs in regular constant force window balances (in which the coil springs are located in a fixed position at the top of the window jamb channel), adding additional springs to inverted constant force balances requires modifications of the shoes, or the addition of supplemental or companion spring carriers. Third, dust and debris from new construction or aging installations may enter the coil spring, thereby preventing proper operation thereof. What is needed then, is an inverted constant force balance that addresses these and other shortcomings. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to a window balance having a shoe body including an elongate portion including at least one carrier section for supporting a coil spring, and an enlarged portion including a locking element and a cam in communication with the locking element, wherein the enlarged portion has a width greater than a width of the elongate portion. 
     In an embodiment of the above aspect, the window balance includes a coil spring supported in the at least one carrier section. In another embodiment, the coil spring includes a plurality of coil springs and the at least one carrier section includes a plurality of carrier sections. In still another embodiment, a first coil spring defines an opening and wherein a second coil spring defines a tab, wherein the opening is configured to receive the tab. In yet another embodiment, the window balance includes an element for securing the spring to a window jamb channel. In still another embodiment, the securing element is at least one of a spring clip, a mounting bracket, a hook, a screw, and combinations thereof. In another embodiment the securing element includes a mounting bracket having a receiver and wherein the shoe body has a projection adapted to mate with the receiver when the shoe body is proximate the mounting bracket. 
     In another embodiment of the above aspect, the window balance includes an element for wiping a coil spring, the element projecting beyond a side wall of the elongate portion. In another embodiment, the wiping element includes at least one of a fabric pile, a foam projection, a plastic projection, a rubber projection, and combinations thereof. In yet another embodiment, the window balance includes a debris trap located above the at least one carrier section. In still another embodiment, the elongate member defines a groove for receiving a pivot bar of a window sash. 
     In an embodiment of the above aspect, the cam defines a keyhole opening for receiving the pivot bar. In another embodiment the groove is aligned with the keyhole opening of the cam. In yet another embodiment, the elongate portion includes two side walls defining an elongate portion width therebetween. In still another embodiment, the enlarged portion includes a first projection and a second projection, and wherein each of the first projection and the second projection include a side wall defining therebetween an enlarged portion width greater than the elongate portion width. In another embodiment, the shoe body is a unitary component. 
     In an embodiment of the above aspect, the shoe body includes a first component and a discrete second component. In another embodiment, the first component includes the enlarged portion and the second component includes the elongate portion, and wherein the enlarged portion is secured to the elongate portion with a connector. In yet another embodiment, the connector is a hanger. 
     In another embodiment, the invention relates to a method of supporting a tilt-in sash in a window. The method includes providing a shoe body having an elongate portion including at least one carrier section for supporting a coil spring and an enlarged portion including a locking element and a cam in communication with the locking element, wherein the enlarged portion has a width greater than a width of the elongate portion. The method also includes providing a sash comprising a pivot bar, inserting the pivot bar into the cam, and rotating the sash to align with the window. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       There are shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and configurations shown. 
         FIG. 1  is a front schematic view of an inverted constant force window balance system in accordance with one embodiment of the present invention. 
         FIG. 2  is an enlarged partial rear schematic view of the inverted constant force window balance system of  FIG. 1 . 
         FIGS. 3A-3D  are front, side, rear, and perspective schematic views of an inverted constant force window balance system in accordance with another embodiment of the invention. 
         FIGS. 4A-4D  are perspective schematic views of an inverted constant force window balance system in accordance with another embodiment of the invention. 
         FIGS. 5A-5B  are front and rear schematic views of a racking embodiment of an inverted constant force window balance system in accordance with another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a front view of one embodiment of a window balance system  10  in accordance with the present invention. Elements of the window balance include a shoe body  12 , a coil spring  14 , and a mounting bracket  16 . The shoe body  12  may incorporate a generally T-shaped configuration that is similar in certain aspects to a balance shoe described in U.S. Pat. No. 6,679,000, the disclosure of which is hereby incorporated by reference herein in its entirety. The T-shaped shoe configuration may utilize an elongate portion  18  having two side walls  20  defining an elongate portion width X therebetween. Two opposing projections  22  may extend beyond the side walls  20  of the elongate portion form the enlarged portion  24  at a distal end of the shoe body  12 . The projections  22  may each include a projection side wall  26  that define an enlarged portion width Y therebetween. 
     The shoe body  12  may define a longitudinal groove  28  that is designed to receive and permit passage of a pivot bar from a window sash. Existing inverted constant force balances often require that the sash frame or jamb be spread apart in order to load the sash into the shoes on either side of the frame. This may make the sash insertion more difficult during manufacture as well as in the field. With the depicted balance, however, the shoe may have a grooved lead-in that allows “drop in” of the pivot bar during sash installation. This may facilitate faster installation and removal of the sash in both a production environment and in the field. The groove may be open at the bottom proximate a cam  30  that is located within the enlarged portion  24  of the shoe  12 . The cam  30  may include a keyhole  32  for receipt of the pivot bar, when the keyhole opening  32  is rotationally aligned with the groove  28 . During installation of the sash, the pivot bar may slide from the groove  28  directly into the keyhole opening  32  in the cam  30 . The coil spring  14  may be carried in a carrier section near an upper portion of the elongate portion  18  of the shoe body  12 . The carrier section is shown in more detail in the following figures. A free end of the coil spring  14  may be secured to a mounting bracket  16  secured to a window jamb channel with a screw or other element, or the free end may be secured directly to the jamb channel. 
       FIG. 2  depicts an enlarged partial rear view of a proximal end of the inverted constant force window balance  10  of  FIG. 1 . The elongate portion  18  may include a carrier section defined at least partially by curved upper  34  and lower surfaces that reduce friction as the coil spring  14  rotates therein. A central spindle  36  may be utilized to provide stand-off of the shoe  12  from a rear wall of the window jamb channel. Alternatively, the spindle  36  may be used as a mount for a spool hub for certain types of coil springs. The mounting bracket  16  may at least partially define a receiver  38  configured to accommodate a mating projection  40  at the top of the elongate portion  18 . This configuration may prevent the mounting bracket  16  from becoming dislocated prior to installation. The mating projection  40  may be configured to receive one or more wiper systems  42  (generally, one on each side of the shoe  12 ). One typical wiper system  42  may include a supporting spline  44  with a tufted fabric pile  46  projecting therefrom, beyond the side wall  20  of the elongate portion  18 . Dirt and debris (e.g., gypsum dust, sawdust, sand, etc.) are common in new construction atmospheres and can render coil springs inoperable or compromised. The wiper system  42  may wipe the coil clean during each sash opening and closing cycle and may be installed on either side of the elongate portion  18 , depending on the location of the coil. Use of the wiper system  42  may also help reduce air infiltration that occurs as outside air moves vertically through the window jamb channel. The balance shoe  12  may also incorporate one or more debris traps  48  that provide a location for dust and debris to collect, without settling on the top of the coil. 
       FIGS. 3A-3D  are front, side, rear, and perspective schematic views of another embodiment of an inverted constant force window balance  110 . The depicted window balance shoe includes two carrier sections  134  and a corresponding number of coil springs  114 . Any number of carrier sections  134  and corresponding (or fewer) coil springs  114  may be utilized depending on the intended application of the window balance  110 . In this embodiment, the wiper system  142  is a flexible rubber element that is secured to the top of the elongate portion  118 . Alternatively, a foam element or a plastic element may be utilized to wipe the coil. The free end of the coil spring  114  may be secured to the window jamb channel with a mounting bracket, a spring clip, screw, or other element  150 . Alternatively, the free end of the coil spring  114  may be formed into a hook or tab that may be inserted into an opening formed in the window jamb channel. As depicted in  FIG. 3A , this embodiment also includes a groove  128  and a corresponding cam keyhole opening  132 . As depicted in  FIG. 3C , this embodiment also includes a receiver  138 , a mating projection  140 , and a debris trap  148 . 
     A locking element  152  in communication with the cam  130  is depicted in  FIG. 3C . This locking element may be a thin piece of metal or plastic with ends configured to retract within or project beyond the side walls  126  of the enlarged portion  124 , so as to engage the window jamb channel upon rotation of the cam  130 . In other embodiments, a locking plate may be forced by rotation of the cam  130  into a rear wall of the jamb channel to lock the shoe in place. Other elements of the window balance are described in conjunction with  FIGS. 1 and 2 . 
     Both the enlarged  124  and elongate  118  portions may include front  124 ′,  118 ′, and rear surfaces  124 ″,  118 ″, respectively, and the distances therebetween define the depths of those portions (A for the depth of the enlarged portion, B for the depth of the elongate portion), as seen in  FIG. 3B . The dimensions of the elongate and enlarged portions of the shoe body may facilitate insertion of the shoe body into a window jamb channel. Window jamb channels may include a rear wall, two side walls, and two front flanges projecting from the side walls parallel to the rear wall, leaving a space for vertical travel of the pivot bar with the sash. The configuration of the shoe  112  of the present invention allows the shoe  112  to be inserted into the jamb channel without deforming the flanges. In prior art window balances, such as those described in the Background, to replace the balance, a large cutout or extensive deflection and/or heating of the jamb channel may be required. The cutout typically allows the shoe to be removed; whereas, heating the jamb channel softens the flanges such that they can be deformed to remove the shoe. The depicted balance, however, may only require a small notch located at some point in the jamb, typically at the top of the window, hidden behind a sash stop. The top of the elongate portion  118  (i.e., the top curved surface  131  of the carrier section with the wipers) can exit through this small notch and the balance shoe body  112  may be removed in accordance with the method described in FIGS. 10A-13B of U.S. Pat. No. 6,679,000 by a series of rotational steps. The coils may remain in the jamb channel, mounted to the mounting bracket  116 , or may be removed individually through the small notch. 
     The depth A of the enlarged portion  124  may be such that the enlarged portion  124  may be inserted bottom surface  154  first into a window jamb channel, such that the bottom surface  154  is proximate a rear wall of the jamb channel. In this regard, the enlarged portion depth A may be substantially similar to, but smaller than, the gap between the two flanges. Thereafter, the shoe  112  may be rotated such that the rear surface of the shoe  112  is pointed upward. In order to rotate the shoe  112  to this position, the height of the enlarged portion may be slightly less than the depth of the jamb channel from the rear wall to the front flanges. The top end of the elongate portion  118  may be rotated (with the enlarged portion  124  acting essentially as a pivot) such that the shoe  112  is in the final vertical configuration. The springs  114  in the jamb channel may be aligned within the carrier sections during the rotation to vertical and the sash pivot pin may be inserted via the groove described above. 
     In the depicted embodiment in  FIG. 3D , the coil springs  114  are configured such that a tab  158  located at a free end  155  of the lower coil may be inserted into an opening  156  defined by the free end  157  of the upper coil. This configuration may allow multiple coils to be connected together in parallel engagement in embodiments of the balance shoe  112  utilizing more than a single coil. Alternatively, the free ends  155 ,  157  of each coil may be directly connected to the mounting bracket,  116  other securing element, or to the jamb channel wall. 
     It should be noted that the shoe body of the balance system described herein may be manufactured of unitary construction (e.g., by injection molding) or may be more than one component, if desired.  FIGS. 4A-4D  depict such an embodiment  210 . In this embodiment  210 , the elongate portion  218  includes two elements  218 ′,  218 ″. These elements  218 ′,  218 ″ may be joined with a releasable connection that may include a hook  260  on the lower element  218 ′ and a bar or pin  262  on the upper element  218 ″, as depicted in  FIGS. 4A and 4B . To connect the two elements  218 ′,  218 ″, the hook  260  may be inserted through an opening  264  formed in the upper element  218 ″, then engaged with the bar  262 , forming a secure connection. An optional extension  266  of the hook  260  may be received in a mating recess  268  in the upper element  218 ″ to prevent over-rotation. The two elements  218 ′,  218 ″ are depicted in a connected configuration in  FIGS. 4C and 4D . This two-piece configuration may ease insertion of the device  210  into a window jamb channel. The lower element  218 ′ may be installed in accordance with the method described above. The upper element  218 ″ may be installed in a similar manner, that is, the top end of the upper element  218 ″ may be inserted sideways between the jamb channel flanges and rotated to a position such that the front surface faces upward. The upper  218 ″ and lower  218 ′ elements may then be connected and rotated into the final operating position simultaneously. 
     Other two-piece configurations are also contemplated. For example, the elongate portion may be discrete from the enlarged portion. In that case, the two portions may be connected by a spring hanger or other element that provides a tight fit therebetween. It is still desirable, though, that the enlarged portion of such a shoe body be configured to fit between the flanges of a window jamb channel. 
     Another embodiment of an inverted constant force window balance  310  according to the invention may include a shoe body  312  for use in an improved racking embodiment, as depicted in  FIGS. 5A and 5B . The shoe body  312  may be shorter in many aspects than the previously described embodiments  12 ,  112 , and  212 , such as a shorter elongate portion  318  and a shorter groove  328 . The more compact design may allow for easier handling and servicing of the shoe  312 , especially when in the field, as well as greater sash travel in the window frame. This permits a greater opening of the window, permitting greater access for entry or egress in an emergency situation. The balance  310  may also include a coil spring  314 , a mounting bracket  316 , an enlarged portion  324 , a cam  330  with a keyhole  332 , and a wiper system  342 , amongst other features described above. Because of the size of the groove  328 , the shoe  312  may need to be vertically offset from a corresponding shoe on the other side of a window sash during installation in the jamb or removal. The cam  330  may be in communication with a locking element  352 , such that when the keyhole  332  is aligned with the groove  328 , the locking element  352  engages the window jamb to hold the shoe  312  in place. To permit removal of the sash, the locking element  352  is sufficient to offset the recoil force associated with the coil spring  314 , but not so strong, as to resist forced sliding in the jamb channel by the installer a sufficient distance to permit the pivot bar to disengage from one shoe  312 . When the pivot bar is reinstalled in the keyhole  332 , the shoe  312  is forced into horizontal alignment with the other shoe  312 . The sash is then rotated so that the sash aligns with the window, and the cam  330  rotates and disengages the locking element  352  from the window jamb. This allows each shoe  312  to move freely within the jamb channel to counterbalance the sash. 
     The depicted balance shoe may be formed of any type of polymer suitable for a particular application. Injection molded plastics are particularly desirable to reduce costs of fabrication. Polyurethane, polypropylene, PVC, PVDC, EVA, and others are contemplated for use. Metal could also be used, if desired, for particular heavy sashes. The locking element may be metal or plastic and may be made from stainless steel, to prevent failure associated with use. Other configurations and materials are contemplated. Additionally, the window balance disclosed herein may be utilized in both tilt-in and fixed (i.e., not tilt-in) applications. 
     While there have been described herein what are to be considered exemplary and preferred embodiments of the present invention, other modifications of the invention will become apparent to those skilled in the art from the teachings herein. The particular methods of manufacture and geometries disclosed herein are exemplary in nature and are not to be considered limiting. It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the invention. Accordingly, what is desired to be secured by Letters Patent is the invention as defined and differentiated in the following claims, and all equivalents.