Patent Application
20050091791
1. Field of the Invention
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.
2. Description of the Prior Art
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.
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 be selectively tilted into the home so that the exterior of the sashes can be cleaned from within the home.
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.
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.
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.
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 frame windows. As such, the prior art concerning vinyl frame windows is herein addressed.
Vinyl frame, 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.
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 either support or engage curl springs. Curl springs are constant force coil springs that supply a constant retraction force when unwound.
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.
The curl springs are utilized within the structure of a tilt-in window in two distinct operating systems. In the first operating system, the curl spring moves with the window sash as the window sash moves up and down in the window frame. In the second operating system, the curl spring is fixed and does not move with the window sash.
In the first operating system, where the curl spring moves, the end of the curl spring is anchored to the fixed part of the window frame. The remaining coils of the curl spring are supported by the shoe and move in unison with the shoe. As each shoe moves away from the anchor point, the curl spring unwinds. Conversely, as each brake shoe moves toward the anchor point, the curl spring rewinds. Such an operating system requires that the anchor mounts be set into the tracks of the windows so that the free ends of the curl springs can be anchored to the window frame. However, the presence of the anchor mount in the window track presents a problem to the free movement of the sashes. Often the movement of a window sash must be limited so that it does not contact the anchor mounts that are present. This often prevents a window sash from being able to open as fully as would otherwise be expected.
Another problem that is inherent to many window counterbalance systems is the complexity of the shoes that retain the springs and move with the springs in the tracks of the window frame. Of the various components that create a counterbalance system, one of the most expensive components is the shoe. The shoes must contain a brake mechanism strong enough to lock a window sash in place. In addition, the shoes must engage and retain at least one strong curl spring. Furthermore, the shoe must remain reliable for years of operation. Accordingly, prior art shoes are built with large, wear resistant components that tend to make the prior art shoes expensive and complex to manufacture.
A need therefore exists in the field of vinyl, tilt-in, double-hung windows, for a counterbalance system that has an improved spring anchor mounting assembly that does not limit the movement of window sashes. A need also exists in the field of vinyl, tilt-in double-hung windows for a counterbalance system that provides inexpensive shoe assemblies. As such, window assemblies can be made to be more reliable, less expensive and easier to manufacture. These needs are met by the present invention as described and claimed below.
The present invention is a counterbalance system for a tilt-in window. The counterbalance system includes brake shoes, curl springs and spring anchor mounts. The brake shoe assembly of the counterbalance system has a unique, low cost locking mechanism that uses a looped wire. The brake shoe assembly may also be configured with external rib projections that reduce the friction of the brake shoe assemblies as they move through the tracks of the window.
The spring anchor mount is formed with a recess in its body that enables the tilt latch of a window sash to pass the spring anchor mount within the track of the window frame. As a result, the spring anchor mounts can be placed within the window frame without concern of contact interference with the tilt latch. The result is a lower cost, more reliable counterbalance system for a window that provides a greater degree of movement in the window sashes so that the window sashes can be opened wider than previously possible.
For a better understanding of the present invention, reference is made to the following description of exemplary embodiments thereof, considered in conjunction with the accompanying drawings, in which:
Referring to
At the top of each sash 11, 12 are two tilt latches 19 that extend a predetermined distance into the tracks 18 on the side of each sash 11, 12. The tilt latches 19 are used to disengage the top of a window sash 11, 12 from the track 18 so that the top of a window sash 11, 12 can be tilted inwardly for cleaning.
At the bottom of each of the sashes 11, 12 is a tilt pivot post 21 that also extends into the track 18. When a sash 11, 12 is tilted inwardly, the sash 11, 12 tilts about its tilt pivot posts 21. The tilt pivot posts 21 are received by shoe assemblies 20 that ride up and down within the tracks 18. The shoe assemblies 20 support at least one curl spring 22. The free end of each curl spring 22 is attached to the track 18 via a spring anchor mount 24.
In the prior art, an anchor mount of a curl spring for a particular sash would often have to be mounted below the tilt latch for that sash. In that way, the tilt latch would not have to pass the anchor mount as the window sash moved up and down in the track.
In the shown embodiment, the spring anchor mount 24 is attached to the track 18 above the tilt latch 19. As such, the tilt latch 19 passes the spring anchor mount 24 as the window sash 12 is moved up and down. However, as will later be described, the structure of the spring anchor mount 24 allows the tilt latch 19 to travel past the spring anchor mount 24 without interference. The window sash 12 is therefore capable of opening wider than many prior art window configurations.
Referring to
At least one curl spring 22 is also provided for each side of a window sash. The curl springs 22 provide the tension force that is used to counterbalance the weight of a window sash as it is moved in a window frame. Each curl spring 22 is a length of ribbon steel 23 that is wound in a circular coil. The curl spring 22 applies a generally constant retraction force when the free end 26 of the ribbon steel is pulled away from the coil. The number of curl springs 22 used depends upon the size and weight of the window sash that is to be counterbalanced. Small window sashes may require only a single curl spring 22. Larger window sashes require multiple curl springs 22. In most standard windows, between one and four curl springs 22 are used.
The free end 26 of each curl spring 22 contains a mounting feature, such as a mount hole 27 or a barb that enables the free end 26 of the curl spring 22 to be readily mounted to the spring anchor mount 24.
Each spring anchor mount 24 has at least one side surface that contains a retaining structure 32 for receiving and engaging the free end 26 of the steel ribbon 23 of the curl spring 22. In the shown embodiment, each curl spring 22 is terminated with a mount hole 27. Accordingly, the side surface of the spring anchor 24 includes a retaining structure 32 in the form of a protrusion that is sized to pass into and engage the mount hole 27. Such a configuration is only one of many ways to interconnect the curl spring 22 to the spring anchor mount 24. It will be understood that if the free end 26 of the curl spring 22 were terminated with a screw hole, threaded bores would be present in the spring anchor mount that would enable the free end 26 of the curl spring 22 to be connected to the spring anchor mount 24 with a screw.
In the shown embodiment, each spring anchor mount 24 is capable of engaging and retaining the free end 26 of up to four curl springs 22. Most vinyl window counterbalance systems use between one and four curl springs. As such, a single spring anchor mount 24 is capable of engaging the curl springs of the most common counterbalance configurations.
Each spring anchor mount 24 has an attachment structure that enables the spring anchor mount to be attached to the track in the window frame. In the shown embodiment, the spring anchor mount 24 defines mounting holes 34 that enable the spring anchor mount 24 to be directly mounted to the window frame with screws. As will be later described, alternate attachment structures can be used to lock the spring anchor mount 24 into a set position. The details of the configuration of the spring anchor mount 24 is later described when referencing
In
The rib protrusions 46 can be molded of wear resistant material and added to the side surfaces 44 of the shoe assembly 20. However, in a preferred method of manufacturing, the rib protrusions 46 are molded as part of the shoe assembly 20.
Referring to
The central open area defined by loop 54 of the torsion spring 52 is elongated, where the loop 54 is taller than it is wide. When the shoe assembly 20 is assembled into a window, the pivot arm of a window sash passes into the post access hole 53 (
It is well known in the art of tilt-in windows, that the pivot arms that extend from window sashes typically have non-round cross-sectional profiles. Most commonly, such pivot arms have a rectangular or otherwise oblong configuration. Referring to
Since the ends 64 of the torsion spring 52 do not extend out beyond the side surfaces 44 of the shoe assembly 20, the shoe assembly 20 is free to move up and down in the track defined by the vinyl window frame. The pivot arm 21 expands the torsion spring 52 and retracts the arms of the torsion spring 52 when the window sash is flush in the window frame. Thus, when the window sash is moved up and down in the window's track, the shoe assembly 20 provides little resistance to the movement.
However, when the window sash is tilted inwardly out of the plane of the window frame, the pivot arm 21 in the torsion spring 52 rotates with the window sash. Referring to
From the description of the function of the brake mechanism created by the torsion spring 52, it will be understood that the torsion spring 52 itself is a single, inexpensive component with no secondary moving parts. As such, the torsion spring 52 is a highly reliable brake mechanism that resists wear much better than prior art shoe assemblies that contain complex brake mechanisms with multiple moving parts.
Referring to
A recess 78 is formed in the face surface of the spring anchor mount 24. The recess 78 extends from the top to the bottom of the spring anchor mount 24 passing through both the head section 72 and the body section 74 of the spring anchor mount 24. The recess thins the center of the spring anchor mount 24. Preferably, the recess 78 in the head section 72 reduces the thickness of the head section 72 by at least thirty percent and may be as much as seventy percent.
At least one countersunk screw hole 34 is formed through the spring anchor mount 24 in the area of the recess 78. Mounting screws 79 are provided to attach the spring anchor mount 24 to a surface of the window track through the screw holes 34. Due to the countersunk screw holes 34 and shape of the mounting screws 79, it will be understood that the screws lay flush in the recess 78 and do not protrude into the area of the recess 78.
Referring back briefly to
Referring to
Referring now to
In the spring anchor mount 80 is a looped wire 84. The ends 86 of the looped wire 84 extend out of the sides of the spring anchor mount 80 unless the loop 85 in the center of the looped wire 84 is internally expanded. A key or screwdriver head is inserted into the loop 85 of the looped wire 84. Once a key or screwdriver head is inserted into the loop 85, the key or screwdriver head is turned. When the key or screwdriver head is turned, the loop 85 expands and the ends 86 of the looped wire 84 retract into the spring anchor mount 80.
To install the spring anchor mount 80, a screwdriver head or other key is placed in the loop 85 of the looped wire 84 and turned. This retracts the ends 86 of the looped wire 84. Once the ends 86 of the looped wire 84 are retracted, the spring anchor mount 80 can be moved to any desired position in the window track. Once in a desired position, the key or screwdriver head is removed and the ends of the looped wire 84 extend and engage the sides of the window track, thereby locking the spring anchor mount 80 in place.
Referring to
From
It will be understood that the embodiments of the present invention counterbalance system and its components that are described and illustrated herein are merely exemplary and a person skilled in the art can make many variations to the embodiments 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.
