US2825089A - Pre-tensionable sash balance - Google Patents

Description

INVENTORS'. I GOT LARSON & HOWARD A. SMITH March 4, 1958 A. LARsoN ETAL PRE-TENSIONABLE sAsH BALANCE v Original Filed Aug. 30, 1952 I, p 4 y l1 FIG. I.

March 4, 1958 A. LAR'soN ET AL 2,825,089

' PRE-TENSIONABLE sAsH BALANCE original Filed Aug. so, 1952 l 2 sheets-sheet 2 l .INVENTORS ALGOT LARSON 8 HOWARD A. SMITH f6 FlG.' 35 f4 Ik 71W Armen/fw United States atcnt O l PRE-TENSIONABLE SASH BALANCE Algot Larson, Stamford, Conn., and Howard A. Smith, Chicago, Ill., assignors to Unique Balance Co., Inc., New York, N. Y., a corporation of Illinois Original application August 30, 1952, Serial No. 307,232, now Patent N0. 2,774,100, dated December 18, 1956. Divided and this application October 17, 1956, Serial No. 618,418

6 Claims. (Cl. 16-197) The present invention relates to spiral-operated spring sash balances and embodies more specilically an improved structure whereby the tension of the balance spring may be adjusted.

This application is a division of our copending United States application, Serial No. 307,232, tiled August 30, 1952 (now United States Patent 2,774,100, granted De cember 18, 1956).

Ever since the introduction of tubular spiral operated spring sash balances attempts have been made to devise a suitable means for pre-tensioning the power spring of the balance mechanism to facilitate the installation thereof and to insure the proper tensioning of the mechanism for a desired operation. Installation is greatly simplified when the tension in the power spring of the balance mechanism closely approximates the load of the window sash since the balance mechanism need then only be installed and does not require extensive adjustments.

Also desirable is an easy and simple means to make such minor adjustments of the power spring tension as might be required to reach the final correct balance after installation or to correct changes in the tension that might result from the use ot' the window. These minor adjustments must be capable of being made without disturbing the woodwork or marring the nish of the frame or sash.

Past efforts (which employed ratchet mechanisms and other means) at the solution of these problems have proven to be unsatisfactory. Some of these old means have required special tools or extra parts which were easily lost or mislaid and which were wasteful of labor and materials.

In those past attempts where ratchets were used to pre-tension and to adjust the tension of the power spring of the balance mechanism, the opposing surfaces of the ratchet mechanism have engaged in the horizontal plane perpendicular to the plane of the tensile torce of the power spring. The opposing surfaces of the ratchet mechanism were held in engagement by the tension of the power spring, and as a sudden movement of the window sash caused a sharp reduction in the tension exerted by the power spring the opposing surfaces would become disengaged and the torsional force of the power spring thereby released. To overcome this defect, second vertical springs were employed in the balance mechanism, but their purpose was solely to hold the opposing surfaces of the ratchet in engagement and they did not aid in the balance of the window sash. These supplementary springs were therefore uneconomic and resulted in a more complicated balance structure.

The present invention accomplishes the above objects together with other advantages which will be more readily apparent from the following detailed description made with reference to the accompanying drawings.

ln the drawings: v

Figure 1 is a view in elevation taken on line 1-1 of Figure 2 of a preferred embodiment of the invention as Fatented Mar. 4, 1958 applied to a window assembly, showing in partial -section the tubes and power spring;

Figure 2 is a view in transverse cross-section taken on line 2 2 of Figure 1 and looking in the direction of the arrows;

Figure 3 is a view taken on line 3-3 of Figure 1 and looking in the direction of the arrows, showing the opposing surfaces of the ratchet members in engagement; and

Figure 4 is a view in partial section taken on line 4 4 of Figure l and looking in the direction of the arrows, showing the convolute spring holding in engagement the opposing surfaces of the ratchet mechanism;

Figure 5 is a cross-sectional view taken on line 5--5 of Figure 4 and looking in the direction of the arrows; and

Figure 6 is a view in partial section showing the installed sash attachment plate and ratchet assembly, taken on line 6-6 of Figure 4 and looking in the direction of the arrows.

Referring to the drawings, indicated at Figure 2 is a window frame 10 and upper and lower sashes 11 and 12, respectively. For each of the sashes 11 and 12 there is provided a sash balance mechanism 13, which mechanism is shown in greater detail in Figure 1.

The sash balance mechanism i3 comprises a tube 14 within which a coiled torsion spring 15 is received. The upper end of the coiled spring i5 is secured to a sleeve 16, which together with the tube 14, is lixedly attached to the frame itl by a drive screw 17 or other suitable means. Formed in the sleeve 16 is an inwardly directed detent 18. The coiled spring 15 is secured at its lower end to a nut 19 formed with a slot 20, within which is received a spiral rod 21. Spaced between the sleeve 16 and the nut 19 and within the coiled spring 15 is a tube 22 made of fibre or the like to eliminate noise which may be caused by the metal to metal contact during operation.

The balancing and lifting power of the balance mechanism 13, in accordance with the Vconventional operation of this type of sash balance, is dependent upon the tension of the coiled spring 15 which is varied by the spiral rod 21. An equal lifting power at all points of the run of the sash 11 or 12 is maintained by the varying pitchY of the spirals of the rod 21.

The spiral rod 21 is attached in a slot 23 formed in a ratchet post 24 by a hinge pin 25. The ratchet post 24 is received in an elongated slot 26 formed in an offset end portion 27 of a sash attachment plate 2S. The sashk attachment plate 28 is attached to the bottom of the sash 12 by drive screws 29 and 30 or any other suitable means.

The sash attachment plate 28 is formed of sheet metal with the offset end portion 27 having formed therein the elongated slot 26 which is of sucient width to slidably receive the ratchet post 24. Also formedlat the offset line of the sash plate 28 are a bent-up prong 31 and an opposing pawl 32. The opposing pawl 32 is not oiset, but is in the same plane as the sash attachment plate 28 so as to coincide with notches 33 spaced along the circumference of a head 34 of the ratchet post 24. Also formed in the head 34 is a slot 35 adapted to receive a screwdriver or other similar instrument. from the head 34 of the ratchet post 24 so as to allow a bearing surface 36 is an annular groove 37. Fitted in the annular groove is a convolute spring 33, the open end of which is engaged with the bent-up prong 31 of the sash attachmentlplate 23. The convolute spring 38 serves the dual purposes of locking the ratchet post 24 in the elongated slot 26 and normally urging the opposing pawl 32 and the notches 33 of the ratchet post head 34 into ,engagement while allowing the lateral movement of the Spaced apart U ratchet post 24 in the elongated slot 26 during adjustment of the balance mechanism 13.

The bent-up prong 31 receives the opened end of the convolute spring 3S` and also serves a a guide or stop to locate the sash attachment plate 2i; against the sash, the prong 31 fitting against the inner edge of the sash grooves, as shown in Figure 6.

The balance mechanism 13 is pretensioned in the factory by withdrawing the spiral rod 21 past the inwardly directed detent 18 in the sleeve 15 and, while thesleeve 16 and tube 14 are held stationary, turning the sash attachment plate 2S and spiral rod 21 a predetermined number of turns in the direction increases the tension in the coil spring 15. The spiral rod 21 is then returned into the tube until the upper end of the rod 2l passes the inwardly directed detent 18. The locking detent 13 prevents the rotation of the spiral rod 21 thereby retaining the tension imparted to the coiled spring 15.

The balance mechanism 13 is installed in the vertical grooves in the sashes 11 and i2 with the sash attachment` 28 pivoted so that it is parallel to the axis of the mechanism 13 and having its flat bottom side directed toward the frame jamb 10. The upper end of the mechanism 13 is secured at the head ofthe jamb iti by the drive screw 17. The lower sash 12 is then raised to its highest elevation, at which position the end of the vertically pivoted sash attachment 28 should extend somewhat below the bottom edge of the sash 12. The sash attachment 28 and spiral rod 21 is then pulled down to a point where the sash attachment plate 28 can be pivoted to a horizontal position and, with the bent-up prong 31 against the inner edge of the groove in the sash 12, attached t0 the lower edge of the sash 12 by drive screws 29 and Sii. The distance between the locking detent 1S and the top of the spiral rod 21, as indicated on Figure l, when the spiral rode 21 is fully advanced in the balance mechanisrn 13 is sufficient to allow a margin of safety in this installation procedure.

This installation operation is repeated on the other side of the sash 12 which then can be raised or lowered to any level desired. When the sash 12 is lowered, the end of the spiral rod 21 passes below the locking detent 1S in the sleeve 16 and the arrested torsional tension in coiled spring 1S is released and will counter-balance the sash 12 at any point.

If after installation it is` necessary to increase the ten- .sion of the coiled spring 15, the spiral rod 21 is turned in the direction which increases the tension by a screwdrlver inserted in the slot 35 in the head 34 'of the ratchet post 24. The point of the pawl 32 as it slides out of the ratchet notch 33 and 'along the circumference of the ratchet post head 34 forces the ratchet post 24 back in the elongated `slot 25 against the force exerted by the convolute spring 3?? until the pawl 32 reaches the next notch 33 where the force of the convolute spring 33 will urge the pawl 32 and notch 33 into engagement. This operation is continued until the proper increased tension is secured.

To reduce the tension in the coiled spring 15, external pressure is exerted against the ratchet head 34 to force it in the elongated slot 26 away from the offset line so that the pawl 32 and the notch 33 are disengaged. The torsion of the coiled spring 15 will turn the ratchet post 24 until the next notch 33 is reached and the convolute spring 38 forces the pawl 3?. and notch 33 into engagement. This process is repeated until the desired tension of coiled spring 15 is secured.

From the foregoing it can be seen 4that factory pretensioning is a great convenience andsource ofleconomy of time and `labor to the building trade. ri'he more ac-` curate pre-tension adjustment made by the workers skilled in the manufacture of the balance mechanism `lessens the danger of destructive adjustment 'being made during installation. The easeand facility with which adjustments may be made after installation without rnarrng' the woodwork or nish of the window is obvious from the foregoing.

While the invention has been described with reference to the specific structure shown in the drawings, it is not to be limited save as in the appended claims.

We claim:

l. Window sash balance mechanism` comprising a tubular casing open at its lower end and adapted to be secured to a window jamb, a nut rotatably receivcdin the lower end of said casing and providing access to thc hollow thereof through a slot centrally formed in said nut, a helicai power spring nested in said casing and having opposite ends in secured relation with, respectively, said nut and said casing, said spring opcrably being wound to urge rotation of said nut relative to said casing, a member fixedly connected to said casing and forming in the hollow of said casing a detent disposed radially inward or said spring and'axially intermediate the lower and upper ends of said casing, a spiral rod received in slidable relation in said slot to pass through. said nut up wardly into said casing to engage said detent when the rod is fully advanced into said slot and to disengagc from said detent when said rod is partially retracted from said casing, said engaged rod being held against rotation by said detent, and said held rod engaging the sides of said slotl to restrain said nut from the rotation urged by said wound spring to thereby preclude said spring from unwinding, and means to secure the lower end of said spiral rod to a window sash.

2. Mechanism as in claim l wherein said spiral rod, when fully advanced into said slot, extends for a distance beyond said detent to permit a partial retraction of said rod from said casing through an initial range of retraction for which said rod remains in full engagement with said detent, said rod becoming disengaged from said detent by retraction of said rod beyond said initial range.

3. Mechanism as in claim l wherein said nut as a tubular shank received in said casing and a head adapted to be seated on the rim of the lower end of said casing, said shank serving to maintain said casing and nut in axial alignment during partial retraction of said nut and rod from said casing.

4. Window sash balance mechanism comprising, a tubular casing open at its lower end and adapted to be secured to a window jarnb, a sleeve, inside the hollow of said casing, having an upper section in close fitting and secured relation with said casing and a lower tapered section axially spaced from the lower end of said casing and forming an annular space between said casing and said lower sleeve section, said lower section being characterized by a detent projecting into the hollow ot said casing radially inward of said sleeve, a nut rotatably received in the lower end of said casing and providing access to the hollow thereof through a slot centrally formed in said nut, a helical power spring nested in said casing and extending from an attachment, securing said spring in relation to said nut, upwards through the hollow of said casing into said annular space to an attach ment securing said spring in relation to said sleeve and casing, said spring oper-ably being wound to urge rotation of said nut relative to said casing, a spiral rod rcceived in slidable relation in said slot to pass through said nut upwardly into said casing to engage said detent when the rod is fully advanced into said slot, and to disengage from said detent when said rod is partially rc;` tracted from said casing, said engaged rod being held against rotation by said detent, and said held rod engag ing the sides of said slot to restrain said nut from the rotation urged by said wound spring to thereby preclude said spring from `nnwiriding, and means to secure the lower end of said spiral rod to a window sash.

5. Window sash balance mechanism comprising, a tubular casing open at its lower end and adapted to be sccured to a window jamb, a nut having a tubular shank rotatably received in the lower end otsaid casing and a head adapted to be seated on the rim of said casing at said lower end, said nut providing access to the hollow of said casing through a slot centrally formed in said nut, a sleeve, inside the hollow of said casing, having an upper section in close fitting and secured relation with said casing and a lower tapered section axially spaced from the lower end of said casing and forming an annular space between said casing and said lower sleeve section, said lower section being characterized by a detent projecting into the hollow of said casing radially inward of said sleeve, a helical power spring nested in said casing and extending from an attachment, securing said spring in relation to said nut, upwards through the hollow of said casing into said annular space to an attachment securing said spring in relation to said sleeve and casing, said spring operably being wound to urge rotation of said nut relative to said casing, a spiral rod received in slidable relation in said slot to pass through said nut upwardly into said casing to extend beyond said detent when said rod is fully advanced into said slot, said rod being adapted to engage with said detent when so advanced and when retracted from said casing through an initial range of retraction, and to disengage from said detent when retracted beyond said initial range, said engaged rod being held against rotation by said detent, and said held rod engaging the sides of said slot to restrain said nut from the rotation urged by said wound spring to thereby preclude said spring from unwinding, and means to secure the lower end of said rod to a window sash.

6. Mechanism as in claim 5 further comprising a liber tube disposed in said casing to axially lie between the lower section of said sleeve and the tubular shank of said nut and to radially lie between said helical spring and said spiral rod, said liber tube preventing noisy mechanical contact between said spring and rod.

References Cited in the ile of this patent UNITED STATES PATENTS 491,114 Johnson Feb. 7, 1893 1,926,951 Larson Sept. 12, 1933 2,565,804 De Vries et al Aug. 28, 1951 2,597,459 Dickinson et al May 20, 1952 2,604,655 Peremi July 29, 1952 2,622,267 Peremi Dec. 23, 1952 2,774,100 Larson et al. Dec. 18, 1956

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