Curl spring shoe based window balance system
AssigneeCaldwell Manufacturing Company
InventorNorman R. Westfall
Life of this patent
Estimating the term…
Abstract
A window balance system for a tilt sash uses a pair of constant force curl springs having curled convolutions carried by sash shoes and free end regions mounted in sash shoe channels above the region of travel of the shoes. The recurl tendency of the springs imparts a lift to the curled spring convolutions, and the shoes transmit the lift to the sash. The springs recurl into the convolutions as the shoes rise and uncurl from the shoes into the shoe channels when the shoes move downward, and neither movement requires the springs to slide frictionally within the shoe channels. Each shoe is preferably formed of two identical halves that are assembled to trap the curl spring along with a cam that locks the shoe when the sash tilts.
Claims63
A window sash balance system having a pair of sash shoes running vertically within jamb shoe channels with a sash that runs vertically in jamb sash runs separate from the shoe channels, the sash shoes being biased upward by the force of curl springs, and connections between the shoes and the sash transmitting the upward bias force from the shoe channels to the sash in the sash runs, the balance system comprising:
- a. free end regions of the curl springs being fastened in the shoe channels in regions above the vertical travel of the shoes, and uncurled lengths of the curl springs being laid against walls of the shoe channels above the shoes without sliding frictionally up and down against the shoe channel walls when the shoes move;
- b. the uncurled lengths of the curl springs passing through openings in the shoes to containment regions within the shoes where variable lengths of the springs curl up in convolutions;
- and
- c. containment of the curled convolutions of the springs within the shoes being arranged for applying the upward bias force to the shoes from a recurling force of the curl springs which is exerted in the shoe containment regions.
A curl spring sash balance system comprising:
- a. convolutions of a curl spring being carried by a sash shoe so that the spring can uncurl from the shoe and dispose an uncurled length to lie against a wall of a shoe channel in which the shoe moves alongside and spaced from the balanced sash and so that a recurl tendency of the spring occurring where the uncurled length returns to the curled convolutions imparts a lift that the curled convolutions transmit to the shoe;
- and
- b. a free end region of the curl spring being secured to the shoe channel above the shoe travel so that the curl spring does not move against the shoe channel surface as the shoe moves up and down in the shoe channel.
In a window having a sash supported by counterbalanced shoes in shoe channels located within interiors of jambs having exteriors that engage stiles of the sash, the improvement comprising:
- a. a counterbalanced lift applied to the shoes being provided by the recurl tendencies of curl springs having curled convolutions carried by the shoes and having free end regions fastened within the shoe channels in regions above the travel of the shoes;
- b. axes of the curled convolutions being parallel with a plane of the sash;
- and
- c. the curl springs being arranged for curling up into the shoe-carried convolutions as the shoes move upward with the sash and for uncurling into the shoe channels as the shoes move downward with the sash so that uncurled lengths of the springs do not slide against shoe channel surfaces as the shoes move.
A sash balance system for a tilt sash connected on a tilt axis to a pair of counterbalanced lock shoes that move vertically in jamb shoe channels as the sash moves vertically in sash runs, the balance system comprising:
- a. curled convolutions of a curl spring carried by each of the shoes above the tilt axis to counterbalance the shoes;
- b. the shoes having surfaces below the curled convolutions arranged for bearing slidably against walls of the shoe channels;
- and
- c. the shoes being configured above the bearing surfaces to allow uncurled lengths of the curl springs to pass from the curled convolutions into the shoe channels above the bearing surfaces where the uncurled lengths of the curl springs rest against shoe channel walls during sash movement.
In a counterbalance system for a tilt sash engaging shoes running in shoe channels and counterbalanced by curl springs, the improvement comprising:
- a. a fixed mount for free end regions of the curl springs in the shoe channels above regions of shoe travel;
- b. uncurled lengths of the curl springs resting within the shoe channels so that the uncurled lengths tending to press against the shoe channels are not moved relative to the shoe channels as the shoes move;
- c. convolutions of the curl springs being curled into containment regions carried by the shoes;
- d. the outermost of the curled convolutions being disposed to bear against surfaces of the containment regions arranged to confront the convolutions aside of the uncurled lengths so that the recurling force of the springs tending to curl the springs into the containment regions exerts lifting forces on the shoes;
- and
- e. a connection between the shoes and the tilt sash being spaced from the curled convolutions in the containment regions.
A counterbalance system for exerting vertical lift on a pair of sash shoes running in shoe channels to support a tilt sash running in sash runs and connected to the shoes, the system comprising:
- a. the counterbalance force being provided by a curl spring engaging each of the shoes;
- b. free end regions of the curl springs being fastened in the shoe channels above regions of shoe travel;
- c. curled up convolutions of the curl springs being carried by the shoes to exert a lifting force as a function of the curling tendencies of the springs, the friction of spring movement as the shoes move in the shoe channels being limited to the friction involved in curling and uncurling the spring convolutions;
- and
- d. a connection extending between the shoes and the sash allowing the sash to tilt and be removed from the sash runs while the shoes and the curl springs remain in the shoe channels.
The system of claimer 50 including a pair of the curl springs carried by each of the sash shoes.
Dependencies are inferred from the claim text.