Claims
- 1. A spring cover for an extruded resin jamb liner, said spring cover extending for the full length of said jamb liner and comprising:
- a. a slit dividing said spring cover into two vertical halves disposed to contact each other to keep said spring cover closed along the length of said slit; and
- b. said spring cover halves being resilient enough to be spread apart to allow a sash platform to extend through said slit and move up and down in said slit while said slit remains closed in regions spaced from said platform.
- 2. The spring cover of claim 1 wherein edges of said slit are rounded.
- 3. The spring cover of claim 1 wherein said halves, in cross section, form a D-shaped with a semi-circular region divided by said slit.
- 4. A sash platform comprising:
- a. a connector portion connectable to a spring system and shaped for moving vertically within a spring cover of a resin jamb liner;
- b. a sash support portion pivotally mounted on said connector portion and shaped to support a sash in a region outside of said spring cover;
- c. a neck portion having a narrow width and extending between said sash support portion and a lower region of said connector portion;
- d. said connector portion having a friction shoulder wider than said neck portion, spaced above said neck portion, and facing in the direction of said sash support portion;
- e. said neck portion forming a pivotal interconnection between said sash support portion and said connector portion so that said sash support portion can pivot in either direction from horizontal; and
- f. said sash support portion having a friction surface wider than said neck portion, arranged below said friction shoulder, and disposed to face toward said connector portion.
- 5. The sash platform of claim 4 wherein said neck portion is integral with said connector portion, and said sash support portion connects to and pivots on said neck portion.
- 6. The sash platform of claim 4 wherein said neck portion is integral with said sash support portion and connects to and pivots on said connector portion.
- 7. The sash platform of claim 4 wherein said connector portion includes a wedge connector for interlocking with end coils of a spring.
- 8. A friction system for a sash platform connected to a counterbalance spring system and supporting a sash between a pair of resin jamb liners, said friction system comprising:
- a. a connector portion of said sash platform being vertically movable within a spring cover of said jamb liner and connected to said counterbalance spring system arranged within said spring cover;
- b. said spring cover being divided by a slit into vertical halves that normally close together and are movable apart from each other;
- c. a sash support portion of said sash platform being pivotally connected to said connector portion and having a surface disposed outside of said spring cover for supporting said sash, said sash support portion being tiltable in either direction from horizontal; and
- d. a narrow width neck extending between said connector portion and said sash support portion, said neck extending through said slit in said spring cover and moving said halves of said spring cover apart in the region of said neck, and said neck affording the pivotal connected between said sash support portion and said connector portion.
- 9. The friction system of claim 8 including a friction surface of said sash support portion, wider than said neck, engaging an outside surface of said spring cover, and a friction shoulder of said connector portion, wider than said neck, engaging an inside surface of said spring cover above said friction surface.
- 10. The friction system of claim 8 wherein said neck is integral with and extends from said connector portion.
- 11. The friction system of claim 8 wherein said neck is integral with and extends from said sash support portion.
- 12. The friction system of claim 8 wherein said connector portion has a wedge connector for interlocking with end coils of a spring.
- 13. A method of applying frictional resistance to movement of a sash that is counterbalanced between a pair of resin jamb liners, said method comprising:
- a. forming a vertically extending and normally closed slit in a spring cover of said jamb liner and extending a narrow neck region of a sash platform through said slit so that said neck moves vertical halves of said spring cover apart at said slit in the region of said neck to produce a constant friction load resisting vertical movement of said neck in said slit; and
- b. arranging a friction shoulder on said platform to engage an inside surface of said spring cover and a friction surface on said platform to engage an outside surface of said spring cover below said friction shoulder to deform said spring cover between said friction shoulder and said friction surface as a function of the weight of said sash urging said platform downward and the force of a counterbalance spring system urging said platform upward to produce load-responsive friction, combined with said constant friction load, in resisting vertical movement of said platform.
- 14. The method of claim 13 including forming said sash platform in two parts that are pivotally connected so that a sash support surface of said platform can tilt in either direction from horizontal.
- 15. The method of claim 13 including dimensioning said neck and the distance between said friction shoulder and said friction surface so that said constant friction load is about one-half of said load-responsive friction.
- 16. The method of claim 13 including arranging said neck so that the lightest counterbalance spring system to be used with said platform can raise said platform when the weight of said sash is removed from said platform.
- 17. The method of claim 13 including arranging said load-responsive friction so that with the heaviest sash and counterbalance system to be used with said platform, said friction shoulder and said friction surface do not jam on said spring cover.
BACKGROUND
This joint application is a Continuation-In-Part of copending parent application Ser. No. 058,796, filed June 5, 1987, 5 June now U.S. Pat. No. 4,779,380, issued Oct. 25, 1988, entitled SPRING COVER FRICTION SYSTEM FOR SASH BALANCE, which was the sole invention of one of the joint inventors of this application.
Window balance systems using resin jamb liners with spring covers have generally limited the spring covers to the upper half of each jamb linear and have let sash platforms move up and down with the sashes in the bottom halves of the jamb liners where no spring covers interfere with platform movement. The Suess U.S. Pat. No. 4,570,382 has suggested full length spring covers extending from top to bottom of the jamb liners with open vertical slots through which sash platforms can extend into adjustable friction shoes that ride up and down inside the spring covers. The spring covers require extra internal walls providing tracks for the friction shoes to work against.
Instead of an open slot and extra internal walls in a spring cover, as suggested by Suess, we have discovered a way that a platform can work with a spring cover that is simply slit so that the platform and the spring cover can achieve the friction necessary to prevent hop or drop of the balanced sash. Our friction system not only uses a less expensive construction, but also provides a frictional resistance that is variable as a function of the spring force pulling up on the platform and the weight of a sash resting on the platform.
Our window balance spring cover friction system enables a sash support surface to pivot in either direction from horizontal, to accommodate the 14.degree. slope that is standard for the window sill and the bottom rail of a lower sash. Our system also divides the friction between a fixed load that is constant, regardless of the sash weight and the spring force, and a changeable load that varies as a function of sash weight and spring force. The two friction loads both involve the spring cover of the resin jamb liner and are combined according to our invention to prevent hop and drop of a sash, while allowing easy vertical movement.
Our window balance spring cover friction system applies to a sash that is counterbalanced between a pair of extruded resin jamb liners having spring covers extending for the full vertical length of the jamb liners. A vertical slit divides a spring cover into vertical halves that normally close together, but are resiliently movable apart from each other. A platform for the sash includes a connector portion vertically movable within the spring cover and connected to a counterbalance spring system arranged within the spring cover. A sash support portion of the platform is pivotally connected to the connector portion and has a surface disposed outside of the spring cover for supporting the sash, the sash support portion being tiltable in either direction from horizontal, to accommodate the incline at the bottom of a lower rail of a lower sash, if necessary. The platform also includes a narrow width neck extending through the slit in the spring cover between the connector portion and the sash portion, and the neck affords the pivotal connection between the sash support portion and the connector portion.
The neck moves the halves of the spring cover apart in the region of the neck so that local separation of the spring cover halves, as the neck moves vertically along the slit, produces a constant friction load resisting vertical movement of the platform. The sash support portion has a friction surface wider than the neck and facing inward to engage the outside of the spring cover, and the connector portion has a friction shoulder wider than the neck and facing outward to engage the inside of the spring cover for deforming the spring cover between the friction shoulder and the friction surface. This vertical deformation of the spring cover provides a friction load that varies as a function of the weight of the sash urging the sash support downward and the force of a counterbalance spring system urging the connector upward. The variable friction load combines with the constant friction load to resist hop and drop of the balanced sash.
FIG. 1 is a fragmentary side elevational view of a preferred embodiment of our platform and spring cover friction system, showing a platform in one spring cover of a jamb liner.
FIG. 2 is a lateral cross-sectional view of the system of FIG. 1, taken along the line 2--2 thereof.
FIG. 3 is a vertical cross-sectional view of the system of FIG. 1, taken along line 3--3 thereof.
FIG. 4 is a partially cutaway, side elevational view of another preferred embodiment of a sash platform according to our invention.
FIG. 5 is a front elevational view of the sash platform of FIG. 4.
FIG. 6 is a partially cutaway top view of the sash platform of FIGS. 4 and 5.
FIG. 7 is a partially cutaway elevational view of the sash platform of FIGS. 4-6, arranged within a resin spring cover of a jamb liner.
FIG. 8 is a partially cutaway, side elevational view of another preferred embodiment of our sash platform, shown connected to a counterbalance spring.
FIG. 9 is a front elevational view of the sash platform of FIG. 8.
FIGS. 10 and 11 are cross-sectional views of the neck portion of the sash platform of FIGS. 8 and 9 disposed at different tilt angles within a slit in a resin spring cover.
US Referenced Citations (11)
Continuation in Parts (1)
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58796 |
Jun 1987 |
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Patent Grant
4837976
