1. Field of the Invention
In general, the present invention relates to windows that have sashes that are designed to be easily removed from a window frame. More particularly, the present invention relates to the structure of spacers that are used to prevent a window sash from cocking within a window frame as it is opened and closed.
2. Prior Art Description
There are many types of windows used in modern construction. Some windows are designed to open, some are not. Of the windows that are designed to open, some windows have sashes that open vertically and others have sashes that slide open laterally, or rotate outwardly.
Windows that have vertically opening sashes are the most common window used in residential home construction. Vertically opening windows are either single-hung, having one sash that opens, or double-hung, having two sashes that open. In both single-hung and double-hung windows, a counterbalance system is used to hold a window sash up once it is opened. If no counterbalance system is used, gravity causes the sash of the window to close as soon as it is opened and released.
Counterbalance systems for single-hung and double-hung windows typically use coil springs to counterbalance the weight of the window sashes. The presence of a counterbalance system requires that a substantial space be left between the sash of the window and the jambs of the window frame. The counterbalance system operates in this space. The counterbalance system is protected from view and from contact by using extruded window frame jambs that are generally U-shaped in cross section. The counterbalance system sits within the center of the groove defined by this track and is thus protected from sight.
When a window is manufactured, the sashes of the window are made separately from the frame of the window. The sashes are later assembled into the frame. Due to variations in manufacturing tolerances, the width of a window sash may vary by up to ⅛th of an inch. Likewise, the distance between jambs in a window frame may also vary by up to ⅛th of an inch. As a consequence, if an undersized sash is assembled into an oversized window frame, there may be over ¼ inch of play between the sash and the tracks of the window frame.
If a window sash has too much play in a window frame, the window sash may cock in position when moved by a person or when influenced by the counterbalance system. Additionally, if the window sash cocks in position, a gap may be created between the window and the sill, thereby greatly reducing the insulation rating for that window.
In the prior art, window sashes have been provided with spacers. However, many of the prior art spacers have drawbacks. Many spacer systems require that slots and/or grooves be milled into the structure of the window sash in order to accommodate the spacer. This adds significantly to the cost and manufacturing complexities of the window sash. Such prior art spacers are exemplified by U.S. Patent Application Publication No. 2005/0144845 to Heck et al. Other spacer systems can be retroactively added to existing window sashes, however, the spacers are visible and detract from the clean aesthetics of a flat window sash. Such prior art spacers are exemplified by U.S. Pat. No. 8,424,245 to Kunz et al.
A need therefore exists for a spacer system that can be added in a window assembly, both at its time of manufacture and retroactively, that does not require changes in the window sash and does not detract from the aesthetics of the window sash. This need is met by the present invention as described and claimed below.
USPTO Backgrounds
USPTO Backgrounds