Abstract:
A counterbalance system for a tilt-in window that has tilt post brackets. The tilt post brackets selectively mount to the vertical side elements of a window sash. Accordingly, the tilt post brackets need not be manufactured into the structure of the sash. The tilt post bracket has a vertical section that mounts directly with the vertical side elements of the window sash frame. A brake element extends from the vertical section, therein providing the window sash with a tilt-in pivot post. The brake element provides both a novel braking system and a novel curl spring support structure.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    In general, the present invention relates to counterbalance systems for windows that prevent open window sashes from closing under the force of their own weight. More particularly, the present invention system relates to counterbalance systems for tilt-in windows that use curl springs to create a counterbalancing force.  
           [0003]    2. Description of the Prior Art  
           [0004]    There are many types and styles of windows. One of the most common types of window is the double-hung window. A double-hung window is the most common window found in traditional home construction. A double-hung window consists of an upper window sash and a lower window sash. Either the upper window sash or the lower window sash can be selectively opened and closed by a person sliding the sash up and down within the window frame.  
           [0005]    A popular variation of the double-hung window is the tilt-in double-hung window. Tilt-in double-hung windows have sashes that can be selectively moved up and down. Additionally, the sashes can also be selectively tilted into the home so that the exterior of the sashes can be cleaned from within the home.  
           [0006]    The sash of a double-hung window has a weight that depends upon the materials used to make that window sash and the size of the window sash. Since the sashes of a double-hung window are free to move up and down in the frame of a window, some counterbalancing system must be used to prevent the window sashes from always moving to the bottom of the window frame under the force of their own weight.  
           [0007]    For many years counterbalance weights were hung next to the window frame in weight wells. The weights were attached to the window sash using a string or chain that passed over a pulley at the top of the window frame. The weights counterbalanced the weight of the window sashes. As such, when the sashes were moved in the window frame, they had a neutral weight and friction would hold them in place.  
           [0008]    The use of weight wells, however, prevents insulation from being packed tightly around a window frame. Furthermore, the use of counterbalance weights on chains or strings cannot be adapted well to tilt-in double-hung windows. Accordingly, as tilt-in windows were being developed, alternative counterbalance systems were developed that were contained within the confines of the window frame and did not interfere with the tilt action of the tilt-in windows.  
           [0009]    Modern tilt-in double-hung windows are primarily manufactured in one of two ways. There are vinyl frame windows and wooden frame windows. In the window manufacturing industry, different types of counterbalance systems are traditionally used for vinyl frame windows and for wooden frame windows. The present invention is mainly concerned with the structure of vinyl framed windows. As such, the prior art concerning vinyl framed windows is herein addressed.  
           [0010]    Vinyl framed, tilt-in, double-hung windows are typically manufactured with tracks along the inside of the window frame. Brake shoe mechanisms, commonly known as “shoes” in the window industry, are placed in the tracks and ride up and down within the tracks. Each sash of the window has two tilt pins or tilt posts that extend into the shoes and cause the shoes to ride up and down in the tracks as the window sashes are opened or closed.  
           [0011]    The shoes serve two purposes. First, the shoes contain a brake mechanism that is activated by the tilt post of the window sash when the window sash is tilted inwardly away from the window frame. The shoe therefore locks the tilt post in place and prevents the base of the sash from moving up or down in the window frame once the sash is tilted open. Second, the shoes support curl springs. Curl springs are constant force coil springs that supply a constant retraction force when unwound. Traditionally, curl springs are placed within the shoe in the same way a metal tape is placed within the housing of a tape measure. One end of the curl spring is anchored to the frame of the window while the main body of the curl spring is wound inside of the shoe. As the shoes move within the tracks, the curl spring rotates inside the shoe. Often as the curl spring rotates inside the shoe, the curl spring moves around within the confines of the shoe and makes an undesirable noise.  
           [0012]    Single curl springs are used on windows with light sashes. Multiple curl springs are used on windows with heavy sashes. The curl springs provide the counterbalance force to the window sashes needed to maintain the sashes in place. The counterbalance force of the curl springs is transferred to the window sashes through the structure of the shoes and the tilt posts that extend from the window sash into the shoes.  
           [0013]    Prior art shoes that contain braking mechanisms and support counterbalance curl springs are exemplified by U.S. Pat. No. 6,378,169 to Batten, entitled Mounting Arrangement For Constant Force Spring Balance; U.S. Pat. No. 5,463,793 to Westfall, entitled Sash Shoe System For Curl Spring Window Balance; and U.S. Pat. No. 5,353,548 to Westfall, entitled Curl Spring Shoe Based Window Balance System.  
           [0014]    Prior art shoes for curl spring counterbalance systems are complex assemblies. The shoes must contain a brake mechanism strong enough to lock a sash in place. Furthermore, the shoes must engage and retain the end of at least one strong curl spring. Prior art shoes are always in contact with the tracks on the sides of the window frame. Accordingly, as wear, dirt and grime accumulate over time, it often becomes more difficult for the shoes to move up and down. The shoe of a window assembly therefore often malfunctions.  
           [0015]    If a shoe jams or otherwise malfunctions, the shoe may not enable the tilt post of the window sash to rotate freely as the window sash is tilted inward. As a window sash is tilted inward, a large torque is experienced by the tilt post at the base of the window sash. This torque is used to activate the braking mechanism in the shoe. However, if the shoe jams, slides out of its track, or otherwise malfunctions, the shoe may not allow the tilt post of the window sash to rotate freely. Consequently, the large torque force, created by the window sash being tilted, acts upon the tilt post at the bottom of the window sash. If the tilt post is not free to rotate, the torque force often bends the tilt post or breaks the tilt post off the sash. Once the tilt post is so damaged, it must be replaced. In many models of windows, the tilt post is manufactured as part of the sash structure and cannot be replaced. In such a construction, the entire window sash must be replaced if the tilt post becomes damaged.  
           [0016]    Furthermore, the manufacturing process used to create a window sash with an integral tilt post is complex. As such, the cost of manufacturing such a window sash is far greater than it would be if no tilt post were present.  
           [0017]    A need therefore exists in the field of vinyl, tilt-in, double-hung windows, for a counterbalance system that eliminates the need for shoes. A need also exists in the field of vinyl, tilt-in double-hung windows for a counterbalance system that provides inexpensive, easily installed tilt posts for a window sash. As such, window assemblies can be made more reliable, less noisy, less expensive and easier to repair. These needs are met by the present invention as described and claimed below.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention is a counterbalance system for a tilt-in window that has a specific form and function for the tilt post bracket component of that system. The tilt post bracket selectively attaches to the vertical side elements of a window sash. Accordingly, a tilt post need not be manufactured into the structure of the sash. The tilt post bracket has a vertical section that mounts directly against the exterior of the window sash frame or within the structure of the window sash frame. A brake element extends from the vertical section, therein providing the window sash with a tilt-in pivot post.  
           [0019]    The counterbalance system uses wound spring elements to provide a counterbalancing force to the sashes of the window. The wound springs are configured to define open central regions. Hubs are attached to tilt post brackets that extend from the sashes of the window. The hubs extend into the open central regions of the wound springs, thereby supporting the wound springs within the frame of the window. The brake element is disposed between the wound springs and the remainder of the tilt post brackets. The brake element automatically locks the horizontal post of the tilt post brackets into fixed positions as the sashes of the tilt-in window are tilted inwardly. The brake element creates two braking actions. First, the brake element itself creates an interference fit within the frame of the window as the sashes tilt. Second, the brake element displaces the wound spring and causes the wound spring to press against the frame of the window as the sashes tilt. The two separate braking actions create a strong and effective brake for the tilt posts of the sashes without the use of traditional window brake shoe assemblies.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    For a better understanding of the present invention, reference is made to the following description of an exemplary embodiment thereof, considered in conjunction with the accompanying drawings, in which:  
         [0021]    [0021]FIG. 1 is a partially fragmented view of a window assembly in accordance with the present invention, containing an enlarged view of the counterbalance system contained therein;  
         [0022]    [0022]FIG. 2 is a perspective, exploded view of the counterbalance system shown in FIG. 1;  
         [0023]    [0023]FIG. 3 is a perspective view of a single-piece brake head/tilt post bracket assembly;  
         [0024]    [0024]FIG. 4 is a selectively cross-sectioned view of a window sash showing how the tilt post bracket mounts within the sash;  
         [0025]    [0025]FIG. 5A is a side view of the counterbalance system in a window frame track;  
         [0026]    [0026]FIG. 5B is a front view of the counterbalance system shown in FIG. 5A;  
         [0027]    [0027]FIG. 6A is a side view of the counterbalance system in a window frame track; and  
         [0028]    [0028]FIG. 6B is a front view of the counterbalance system shown in FIG. 6A. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]    Referring to FIG. 1, there is shown an exemplary embodiment of a vinyl, tilt-in, double-hung window assembly  10 . The window assembly  10  has an upper sash  11  and a lower sash  12 . Each of the sashes  11 ,  12  has two side elements  17 . The upper sash  11  and the lower sash  12  are contained within a window frame  14 . The window frame  14  has two vertical sides  16  that extend along the side elements  17  of both sashes  11 ,  12 . Within each of the vertical sides  16  of the window frame  14  is formed a track  18 .  
         [0030]    A tilt post bracket  20  is mounted to the side elements  17  of each sash  11 ,  12  near the bottom of each sash  11 ,  12 . Each tilt post bracket  20  contains a brake head  22  that extends out away from the side of the sash  11 ,  12  and into the tracks  18  in the vertical sides  16  of the window frame  14 . As is later explained in greater detail, a brake head  22  extends away from the sash  11 ,  12  and into the track  18  of the window frame  14 . The brake head  22  serves two purposes. First, the brake head  22  serves as a brake mechanism that locks the bottom of a sash  11 ,  12  in place within the track  18  when a sash  11 ,  12  is tilted inwardly. Second, the brake head  22  serves as a hub for a curl spring  24 , wherein a curl spring  24  passes around the brake head  22 .  
         [0031]    The curl spring  24  rotates about the brake head  22 . The free end of the curl spring  24  is affixed to the window frame  14  higher along the track  18 . Accordingly, the curl spring  24  applies an upward counterbalance force to each sash  11 ,  12  that counteracts the weight of each sash  11 ,  12 .  
         [0032]    Referring to FIG. 2, it can be seen that the tilt post bracket  20  is a structure that has an elongated vertical section  21 . Disposed at the top of the vertical section  21  is a locking projection  23 . The locking projection  23  is used to lock the tilt post bracket  20  in place, as will later be explained.  
         [0033]    The vertical section  21  of the tilt post bracket  20  can be mounted flush to the side element  17  of a window sash  12  or placed in a relief formed in the exterior of the side element  17 . However, in a preferred embodiment, the vertical section  21  of the tilt post bracket  20  passes into the interior of the side element  17  of the sash  12 , in a manner later explained. To facilitate the interconnection between the vertical section  21  of the tilt post bracket  20  and the sash  12 , the side elements  17  of the sash  12  are slightly modified. As will be later shown, the interior of each side element  17  of the sash  12  is not solid. Rather, although each side element  17  of the sash has a solid exterior, internally each side element  17  of the sash  12  is hollow and is reinforced with cross-ribbing. In this manner, the side elements  17  of the sash  12  can be made lighter, stronger and at a lower cost than if the side elements  17  were solid vinyl. In the present invention, a locking hole  27  is formed in each of the side elements  17 . At the base of each side element  17  a relief  29  is formed, to help receive the tilt post bracket  20 , as is later shown.  
         [0034]    The brake head  22  extends horizontally from the bottom of the vertical section  21  of the tilt post bracket  20 . In the shown embodiment, the brake head  22  is shown as an integral part of the tilt post bracket  20 . As a result, the brake head  22  and the vertical section  21  of the tilt post bracket  20  are a single unistructural part. It should be understood, however, that such a configuration is exemplary and that the brake head  22  and the remainder of the tilt post bracket  20  can be made as separate parts. In such an alternate configuration, the brake head  22  is structured so that it passes over the end of a horizontal post that extends from the tilt post bracket  20 . The interconnection between the brake head  22  and the tilt post bracket  20  is a keyed connection that prevents the brake head  22  from being rotated without the remainder of the tilt post bracket  20 .  
         [0035]    The brake head  22  is a structure that includes flanges  30  and a cylindrical hub  32  that extends behind the flanges  30 . The purpose and function of the flanges  30  is later explained. The cylindrical hub  32  is sized to pass into an annular spring bearing  34 . As such, the annular spring bearing  34  is free to rotate around the cylindrical hub  32  of the brake head  22 . The spring bearing  34  passes into the center of a standard window curl spring  24 . The spring bearing  34  may be slotted so that the spring bearing  34  can be momentarily compressed when inserted into the center of the curl spring  24 . Alternatively, the spring bearing  34  may have fingers or other features that mechanically engage the curl spring  24  and lock the spring bearing  34  into place in the center of the curl spring  24 . Once inserted into the center of the curl spring  24 , the spring bearing  34  expands so that no space exists between the exterior of the spring bearing  34  and the interior of the curl spring  24 .  
         [0036]    Referring to FIG. 3, the brake head  22  and tilt post bracket  20  are shown combined in a single piece. From FIG. 3, it can be seen that the brake head  22  has a complex shape. The cylindrical hub  32  of the brake head  22  comprises the majority of the brake head  22 . However, flanges  30  radially extend from the cylindrical hub  32  at one end of the cylindrical hub  32 . The flanges  30  extend above and below the cylindrical hub  32 . No flanges  30  extend from the sides of the cylindrical hub  32 . As a result, the flanges  30  combine to provide the brake head  22  with an elongated configuration at one end of the cylindrical hub  32 .  
         [0037]    The flanges  30  above and below the cylindrical hub  32  have a stepped structure. Each of the flanges  30  has a distal edge  36  at their tip and a second edge  38  interposed between the distal edge  36  and the center of the hub  32 . The flanges  30  have a first thickness near the distal edge  36 . Further down from each distal edge  36  is a step that forms the second edge  38 . Accordingly, below the second edge  38 , the flanges  30  are thicker and lay flush with the front end of the cylindrical hub  32 . However, above the second edge  38 , the flanges  30  are recessed. The flanges  30  are further thinned near the distal edge  36  by the presence of a bevel  37  that leads to the distal edge  36 .  
         [0038]    The vertical section  21  of the tilt post bracket  20  also has a complex shape. The vertical section  21  has a locking projection  23  at its top end. The length of the vertical section  21  between the brake head  22  and the locking projection  23  is also varied. The purpose of the varied shape is to cause the vertical section  21  of the tilt post bracket  20  to conform to the internal shape of a void in the side element  17  (FIG. 2) of the window sash  12  (FIG. 2).  
         [0039]    Referring to FIG. 4, it can be seen that within the side elements  17  of the sash  12  are voids  33 . The voids  33  are molded into the vinyl structure of the sash&#39;s side elements  17  to reduce weight, reduce cost, reduce expense and increase strength. The vertical section  21  of the tilt post bracket  20  extends into a void  33  in the side element  17  of the sash  12 . The vertical section  21  of the tilt post bracket  20  is sized to be the same size as the void  33 , so as to fill the void and create maximum surface-to-surface contact between the vertical section  21  and the defining surfaces of the void  33 .  
         [0040]    From FIG. 4, it can be seen that the vertical section  21  thins near the locking projection  23 . As such, the vertical section  21  of the tilt post bracket  20  is slightly flexible in the thinned area below the locking projection  23 . Accordingly, as the vertical section  21  of the tilt post bracket  20  passes into the void  33  in the sash&#39;s side element  17 , the vertical section  21  below the locking projection  23  will deform slightly until the locking projection  23  reaches the locking hole  27 . Once at the locking hole  27 , the locking projection  23  pops into the locking hole  27  and the vertical section  21  is no longer slightly deformed. Accordingly, the passing of the locking projection  23  into the locking hole  27  mechanically locks the tilt post bracket  20  into the side element  17  of the sash  12 .  
         [0041]    Back in FIG. 2, a relief  29  was shown at the bottom of the side element  17  of the sash  12 . In FIG. 4, it can be seen that the relief  29  (shown only in FIG. 2) allows the tilt post bracket  20  to pass into side element  17  of the sash  12  so as not to protrude too far below the bottom of the sash  12 .  
         [0042]    Referring now to FIGS. 5A and 5B, it can be seen that the track  18  in each side of the window frame is accessible through a long slot  40  that runs along the length of the window frame. When the window sash  12  (FIG. 1) is not tilted, the tilt post bracket  20  (FIG. 2) orients the brake head  22  in the track  18  so that the flanges  30  on the brake head  22  do not engage the window track  18  or the slot  40  at any point. The brake head  22  is therefore free to move up and down along the length of the track  18  without touching the track  18 . The brake head  22  supports the spring bearing  34  (FIG. 2) in the center of the curl spring  24 . Accordingly, as the brake head  22  moves up and down in the track  18 , the curl spring  24  is moved up and down in the track  18 , wherein the curl spring  24  either winds or unwinds depending upon the direction of movement. However, the curl spring  24  is not confined within a shoe, and the only movement of the curl spring  24  is its rotation around the brake head  22 . As such, each curl spring  24  is prevented from making contact noise as it winds and unwinds.  
         [0043]    It will be understood that when the sash  12  (FIG. 2) of the window is closed, the brake head  22  and the curl spring  24  are both free to move in the track  18 . This allows the window sash  12  (FIG. 2) to move up and down unencumbered in the window frame.  
         [0044]    Referring to FIGS. 6A and 6B, it can be seen that when the sash  12  (FIG. 1) of the window is tilted forward, the tilt post bracket  20  rotates. This causes the brake head  22  to rotate in the track  18 . As the brake head  22  rotates in the track  18 , two simultaneous braking actions occur that lock the brake head  22  in place within the track  18 . The first braking action is caused by the flanges  30  that extend from the brake head  22 . As the brake head  22  rotates, the flanges  30  rotate towards 90 degrees within the confines of the track  18 . The second edges  38  of the flanges  30  rotate within the slot opening  40 . The distal edges  36  of the flanges  30  rotate into the track  18  just behind the slot opening  40 . The bevel  37  leading to the distal edges  36  of the flanges  30  prevent the distal edges  36  from catching on the open edges of the slot  40  as the flanges  30  rotate past these edges. As the flanges  30  rotate toward 90 degrees, contact occurs between the flanges  30  and the track  18  at two different points. As the distal edges  36  of the flanges  30  rotate, they contact the interior of the track  18 , causing an interference fit. Simultaneously, the second edges  38  rotate and contact the open edges of the slot  40 . This also causes an interference fit. Consequently, as the brake head  22  rotates, an interference occurs between the structure of the track  18  and both the distal edges  36  and the second edges  38  of the flanges  30 . This wedges the brake head  22  in place and prevents the brake head  22  from being moved in the track  18 .  
         [0045]    As the brake head  22  is being rotated in the track  18  to cause an interference fit, yet another braking action is occurring. As the brake head  22  rotates in the track  18 , the distal edges  36  of the flanges  30  enter the inside of the track  18 . Due to the thickness of the flanges  30 , the cylindrical hub  32  is driven farther into the track  18  as the distal edges  36  of the flanges  30  rotate into the inside of the track  18 .  
         [0046]    The cylindrical hub  32  supports the curl spring  24  within the track  18 . As the cylindrical hub  32  is driven farther into the interior of the track  18  by the entrance of the flanges  30  into the track  18 , the curl spring  24  is driven farther into the interior of the track  18 . The brake head  22  is sized so that as the flanges  30  turn into the track  18 , the curl spring  24  becomes compressed between the rear wall  46  of the track  18  and the flanges  30  on the brake head  22 . The combined width of the curl spring  24  and the flanges  30  of the brake head  22  in the track  18  is wider than the track  18 . Thus, an interference fit is created when the brake head  22  is rotated and the flanges  30  enter the track  18 . The interference fit biases the curl spring  24  against the rear wall  46  of the track  18 . This prevents the curl spring  24  from moving in the track  18 . The abutment against the rear wall  46  of the track  18  also hinders the curl spring  24  from winding or unwinding.  
         [0047]    Accordingly, when the brake head  22  is rotated from the free moving orientation of FIG. 5A into the locked position of FIG. 6A, multiple locking actions occur. The flanges  30  of the brake head  22  contact the interior of the track  18  and the edges of the slot  40  in the track  18 , thereby locking the brake head  22  in place. Furthermore, the brake head  22  biases the curl spring  24  against the rear wall  46  of the track  18 , thereby locking the curl spring  24  in place. The combined locking actions create a very strong overall locking mechanism that prevents the tilt post bracket  20  and the curl spring  24  from moving within the window track  18  once the window sash  12  (FIG. 1) is tilted.  
         [0048]    From the description of the function of the brake head  22 , it will be understood that the brake head  22  itself is a solid object with no moving parts. The brake head  22  is either part of, or attached to, the tilt post bracket  20  and rotates with the tilt post bracket  20 . When in a first orientation, the brake head  22  moves freely in the track  18  of the window. When rotated, the brake head  22  creates multiple interferences with both the structure of the track  18  and the curl spring  24  in the track. However, since the brake head  22  itself is a solid, one-piece structure with no moving parts, it is highly reliable and resists wear much better than prior art brake shoes that contain complex moving brake assemblies.  
         [0049]    It will be understood that the embodiments of the present invention counterbalance system that are described and illustrated herein are merely exemplary and a person skilled in the art can make many variations to the embodiment shown without departing from the scope of the present invention. All such variations, modifications and alternate embodiments are intended to be included within the scope of the present invention as defined by the appended claims.