Mounting system for mounting a coil spring to a window frame in a sash counterbalance system

Abstract

An anchoring system used to anchor a ribbon spring to a guide track. A mounting slot is formed in the guide track that provides access to the internal gap space. A counterbalance spring is provided having an offset tab section proximate a free end. A barb flap is formed by bending a segment of the counterbalance spring from the offset tab section. The offset tab section with barb flap are extended into the gap space through the mounting slot. As the counterbalance spring is unwound, a bias is created that engages both the offset tab section and the barb flap within the gap space. This locks the free end of the counterbalance spring in place without the need of any mechanical fastener.

Claims

1. A system comprising: a window frame having a first wall and a second wall that are separated by a gap space, wherein a guide track is defined in part by said first wall, said first wall having a first surface that faces said guide track and an opposite second surface that faces said gap space, wherein said gap space has a first width between said first wall and said second wall; a mounting slot formed in said first wall; a ribbon spring wound into a coil, said ribbon spring terminating with a free end, wherein said ribbon spring is bent into an anchor configuration proximate said free end, wherein said anchor configuration includes a first bend in said ribbon spring and a second bend in said ribbon spring that define a lateral section of said ribbon spring therebetween, and an offset tab section that extends from said second bend to said free end, said offset section having a first length that is longer than said first width of said gap space; and a barb flap bent from said offset tab section and extending from said offset tab section at an angle; said coil being positioned on one side of said first wall and both said offset tab section and said barb flap being positioned in said gap space, therein positioning said lateral section of said ribbon spring within said mounting slot, wherein said offset tab section bends to fit in said gap space and biases said barb flap against said opposite second surface of said first wall within said gap space.

2. The system according to claim 1, wherein said offset tab section has a flexible segment and said offset tab section bends in a flexible segment within said gap space.

3. The system according to claim 2, wherein said barb flap is created by a cut in said offset tab section, wherein said cut also creates said flexible segment of said offset tab section.

4. The system according to claim 1, wherein said first length of said offset tab section is at least twenty-five percent longer than said first width of said gap space.

5. The system according to claim 1, wherein said first bend is 90 degrees15 degrees.

6. The system according to claim 5, wherein said second bend is 90 degrees15 degrees.

7. A system comprising: an extruded window frame having an exterior wall, an interior wall, and a gap space separating said exterior wall from said interior wall, wherein said gap space has a first width; a mounting slot formed in said exterior wall to provide access to said gap space; a counterbalance spring terminating with a free end, wherein said counterbalance spring is bent into an anchor configuration proximate said free end, wherein said anchor configuration includes a lateral section between two bends and an offset tab section that extends from said lateral section to said free end, wherein said offset tab section has a first length that is longer than said first width; a barb flap extending from said offset tab section at an angle, wherein said lateral section of said counterbalance spring extends through said mounting slot and wherein said offset tab section bends to fit in said gap space causing said barb flap to be biased against said exterior wall within said gap space.

8. The system according to claim 7, wherein said offset tab section has a flexible segment, and said offset tab section bends in said flexible segment within said gap space.

9. The system according to claim 8, wherein said barb flap is created by a cut in said offset tab section, wherein said cut also creates said flexible segment of said offset tab section.

10. The system according to claim 7, wherein said first length of said offset tab section is at least twenty-five percent longer than said width of said gap space.

11. The system according to claim 7, wherein each of said bends in said anchor configuration is 90 degrees15 degrees.

12. The systems according to claim 11, wherein each of said bends in said anchor configuration bends in an opposite direction.

13. The system according to claim 11, wherein each of said bends in said anchor configuration bends in a common direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 is a fragmented perspective view of an exemplary embodiment of a counterbalance system for a window;

(3) FIG. 2 is an enlarged perspective view of a coil spring used within the counterbalance system;

(4) FIG. 3 is a side view of a coil spring and a selectively cross-sectional view of a segment of a guide track containing a mounting slot;

(5) FIG. 4 shows the same matter as FIG. 3 with the coil spring partially engaging the mounting slot;

(6) FIG. 5 shows the same matter as FIG. 4 with the coil spring fully engaging the mounting slot; and

(7) FIG. 6 shows an alternate embodiment of a coil spring and a selectively cross-sectional view of a segment of a guide track containing a mounting slot.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) Referring to FIG. 1, the counterbalance system 10 for a window sash 12 of a window assembly 11 is shown. The window sash 12 has a sash frame 15 that selectively engages a spring carriage 16. In the shown embodiment, the spring carriage 16 holds a single counterbalance spring 30. It will be understood that the spring carriage 16 can be configured to hold multiple counterbalance springs. A spring carriage 16 with a capacity of one spring coil 30 has been selected for the sake of clarity. It will also be understood that the spring carriage 16 can be any prior art spring carriage and/or brake shoe assembly that is designed to hold the coil of a counterbalance spring.

(9) The spring carriage 16 rides in a guide track 18 that is formed in the window frame 20 on the sides of the window sash 12. The guide track 18 often has an extruded plastic construction, and such a construction is shown. Mounting slots 22 are formed in the guide track 18 at the points where a counterbalance spring 30 is to be connected to the window frame 20. The mounting slots 22 each have a width that is just slightly wider than the steel ribbon 32 used to create the coil spring 30. Furthermore, each mounting slot 22 has a height that is slightly larger than the gauge of steel used in the steel ribbon 32.

(10) The counterbalance spring 30 is a wound ribbon spring that is biased into a coil 34. Accordingly, the counterbalance spring 30 resists being unwound from the coil 34. A counterbalance spring 30 is made from a steel ribbon 32 that has two ends 35, 36. When the steel ribbon 32 is wound into the shape of the counterbalance spring 30, its first end 35 is located on the interior of the coil 34. The second end 36 of the steel ribbon 32 terminates on the exterior of the coil 34.

(11) The steel ribbon 32 approaching the second end 36 is formed into an anchor configuration 40. The anchor configuration 40 is specifically configured to mechanically engage a mounting slot 22 in the guide track 18, as will later be explained in detail.

(12) Referring to FIG. 2 in conjunction with FIG. 1, it can be seen that the anchor configuration 40 begins when the steel ribbon 32 that extends from the coil 34 reaches a first bend 42. At the first bend 42, the direction of the steel ribbon 32 changes by a first angle, which is 90 degrees15 degrees. Accordingly, after the first bend 42, the steel ribbon 32 generally extends away from the center of the coil 34.

(13) The steel ribbon 32 extends through a short lateral section 44 as it progresses between the first bend 42 and a second bend 46. The lateral section 44 has a length L1. At the second bend 46, the direction of the steel ribbon 32 changes by a second angle, which is 90 degrees15 degrees back into its original orientation. This creates an offset tab 48 that extends from the second bend 46 to the second end 36 of the steel ribbon 32. The offset tab 48 has a length L2, the significance of which is later explained.

(14) A barb flap 38 is formed at, or near, the center of the offset tab 48. The barb flap 38 is created by a cut in the steel ribbon 32 that defines the profile of the barb flap 38. However, the barb flap 38 has one fixed edge 39 that remains part of the steel ribbon 32, therein retaining the barb flap 38 as part of the steel ribbon 32. The fixed edge 39 is positioned on the barb flap 38 closest to the second end 36 of the steel ribbon 32. The barb flap 38 is slightly bent along the fixed edge 39. This causes the barb flap 38 to protrude as an angled barb from the offset tab 48.

(15) The angle of the barb flap 38 creates an opening 41 in the offset tab 48. The opening 41 is positioned in the center of the offset tab 48 at a point equidistant from the two parallel side edges 43 of the steel ribbon 32. The opening 41 in the offset tab 48 creates thinned sections 45 of the steel ribbon 32 on either side of the opening 41. The thinned sections 45 extend from the opening 41 to the side edges 43 of the steel ribbon 32. Being thinner than any other section of the steel ribbon 32 along the offset tab 48, the thinned sections 45 create an area 47 along the offset tab 48 that is more flexible than the other areas of the offset tab 48. It is, therefore, easier for the offset tab 48 to bend in the flexible area 47 than in any other area along the offset tab 48.

(16) Referring to FIG. 3 in conjunction with FIG. 1 and FIG. 2, it can be seen that the guide track 18 is preferably an extruded component. When a guide track 18 of a window frame is manufactured, the guide track 18 is typically extruded with a series of parallel walls that are separated by gap spaces. This maximizes the strength of the guide track 18 while simultaneously minimizing the amount of material needed to form the guide track 18. The result is that the guide track 18 has an exterior wall 24 that faces the window sash 12, and an interior wall 26 that is parallel to the exterior wall 24. The exterior wall 24 and the interior wall 26 are separated by a gap space 28 having a width W1. The mounting slot 22 is formed in the exterior wall 24 of the guide track 18, therein providing access to the gap space 28 between the exterior wall 24 and the interior wall 26.

(17) Referring to FIG. 3, FIG. 4, and FIG. 5, it can be seen that the length L1 of the offset tab 48 is at least twenty-five percent longer than the width W1 of the gap space 28 between the exterior wall 24 and the interior wall 26 of the guide track 18. The offset tab 48 is inserted into the mounting slot 22. The barb flap 38 extending from the offset tab 48 is angled away from the second end 36 to the steel ribbon 32. As such, the barb flap 38 is oriented to pass through the mounting slot 22 without binding on the exterior wall 24 during the insertion process. The flexible areas 47 on the sides of the barb flap 38 also enable the offset tab 48 to flex during the insertion process. The flexing helps the barb flap 38 to pass through the mounting slot 22 and prevent the second end 36 of the steel ribbon 32 from binding against the interior wall 26. Since the length of the offset tab 48 is longer than the width of the gap space 28, the offset tab 48 contacts the interior wall 26 at the opposite side of the gap space 28 during the insertion process. The offset tab 48 flexes as it is deflected by the interior wall 26. This enables the offset tab 48 to continue to pass into the gap space 28 until the lateral section 44 of the anchor configuration 40 reaches the mounting slot 22.

(18) As the lateral section 44 of the anchor configuration 40 reaches the mounting slot 22, the lateral section 44 passes into the mounting slot 22. The mounting slot 22 is formed through the exterior wall 24 of the guide track 18. The exterior wall 24 of the guide track 18 is made from extruded plastic and has a thickness that is typically about .sup.th of an inch. The lateral section 44 of the anchor configuration 40 has a length that is just slightly larger than the thickness of the exterior wall 24 of the guide track 18. As a consequence, the lateral section 44 of the anchor configuration 40 in the mounting slot 22 serves as a pivot fulcrum. Within the gap space 28, the offset tab 48 pivots until the offset tab 48 contacts the interior wall 26 and the barb flap 38 contacts the exterior wall 24. The offset tab 48 is caused to bend by the narrowness of the gap space 28. This bend biases the barb flap 38 against the exterior wall 24. In this orientation, the presence of the barb flap 38 and the dual contact points prevents the offset tab 48 from exiting the mounting slot 22. The anchor configuration 40 is, therefore, mechanically interlocked with the mounting slot 22 and cannot be unintentionally withdrawn.

(19) As the counterbalance spring 30 is pulled downward by the movement of the window sash, the counterbalance spring 30 begins to unwind along the outside surface of the exterior wall 24. The sections of the counterbalance spring 30 that unwind from the coil 34 are biased against the outside surface of the exterior wall 24 of the guide track 18. The steel ribbon 32, therefore, remains pressed against the guide track 18 and out of sight as the counterbalance spring 30 moves up and down while winding and unwinding.

(20) The anchor configuration 40 can be inserted into the mounting slot 22 by a simple manipulation of the counterbalance spring 30. This manipulation can be easily automated for manufacture. Furthermore, the counterbalance spring 30 need not be partially unwound in order to connect the counterbalance spring 30 to the guide track 18. Lastly, the mechanical interconnection between the anchor configuration 40 and the mounting slot 22 does not require the use of mechanical fasteners, such as screws or locking pins. It will therefore be understood that the anchor configuration 40 of the counterbalance spring 30 can be connected to a guide track 18 in a window frame in a highly cost effective and labor efficient manner.

(21) Referring to FIG. 6, an alternate embodiment of a counterbalance spring 60 is shown. In this embodiment, the counterbalance spring 60 has the same configuration as the counterbalance spring previously shown, except that the offset tab 62 is bent in the opposite direction at the second bend 64. As a result, the slot anchor configuration 66 is provided with a hooked shape.

(22) When inserted into a mounting slot 22, it will be understood that the offset tab 62 of the slot anchor configuration 66 will pass through the mounting slot 22. The offset tab 62 then extends downwardly and presses against the interior wall 26 of the guide track 18.

(23) It will be understood that the embodiments of the present invention are merely exemplary and that a person skilled in the art can make many variations to those embodiments. For instance, the length of the offset tab can be varied and the curvature of the offset tab can be varied. The first and second bends can be more or less than ninety degrees. All such variations, modifications, and alternate embodiments are intended to be included within the scope of the present invention as defined by the claims.