US2782456A - Heavy duty window balance - Google Patents

Description

Feb. 26, 1957 KENYQN 2,782,456

HEAVY DUTY WINDOW BALANCE Filed April 21, 1954 4 Sheets-Sheet l INVENTOR Bqfra'no F Kenyon ffor'neg Feb. 26, 1957 B. F. KENYON HEAVY DUTY WINDOW BALANCE 4 Sheets-Sheet 2 Filed April 21, 1954 IN V EN TOR. Bfrfrono F Kenyon Affomey Feb. 26, 1957 B. F. KENYON HEAVY DUTY WINDOW BALANCE 4 Sheets-Sheet 3 Filed April 21. 1954 INVENTOR.

Berrrand FKe/vym M6? Qf 34 fforr Feb. 26, 1957 B. F. KENYON 2,732,455

HEAVY DUTY WINDOW BALANCE Filed April 21; 1954 4 SheetsSheet 4 J Berfrand jail/on y. W 5. W

ffomev limited than it now is.-

United States Patent HEAVY DUTY WINDOW BALANCE Bertrand F. Kenyon, Grand Rapids, Mich., assignor to Mechano Gear Shift Company, Grand Rapids, Mich, a corporation of Michigan Application April 21, 1954, SerialNo. 424,559

3 Claims. (Cl. 16198)' Thisinvention relates to window orv like balances, being generally concerned with balances ofthe wound spring type, which have spring actuated rotative drums and tapes or cables wound on the drums attached to a vertically sliding. window sash which is raised and lowered.

The weight of a window to which such type of balance is applied is constant. The spring power acting against such weight varies with the drum rotation, the spring in general being wound and exerting a stronger lifting force; which progressively increases as the window sashis lowered and likewise decreases when the sash is raised. Without the factor of frictionof the window. sash sliding inthe frame in which it is mounted, and also inertia, the range oftravel of a window sash would be even more As it is, the range of. vertical travel or movement of a window sash is curtailed and limited. It frequently happens that on loweringa window sash the lifting force of the spring balance is increased to.- such: an extent that the sash may be lifted above a desired lowermost position, particularly ona decrease of friction as may occur, at least with wood windows. and frames, with changing atmospheric; conditions. Likewise, as the spring lifting force decreases as a sash is raised; apoint is, quickly reached where the balance will not; hold a windowsash in its upper. position ifit is liftedabove such point. Accordingly, thenormal spring balance of the wound spring type has heretofore been limited in use. to window sashes, the lifting and lowering of whichis small compared to many sashes, particularly in windows of the so-called heavy duty charactenusually of metal, slidably' mounted, for vertical movements in metal frames.

Window sashes which are large and have a relatively long vertical travel have not been successfully equipped withspring balancesbecause of suchwidely varying and changing forces of springs in spring balances applied to the sliding window sash, the weight of which is constant.

In the present invention it is an object and purpose thereof to balance a window sash or the like of whatever weight, light, medium or heavy, by a wound spring balance in a manner to obtain substantially the same results asv those obtained by weightswhich have long been used to substantially counter-balance the weight of the window sash. and with which. any range of vertical travel ofa window sash may be effectively: taken careof.

To this end, the weight of a window sash being constant, the moment of force acting upon the sash throughout its travel is rendered substantiallyv constant at all points of its travel, at least approximately so, so as to be practical and serviceable and serve its desired functions with any and all weights of window sashes and with any and all lengths of travel thereof. As the spring (or springs) is wound and spring force increased progressively, the moment arm through which the force operates is correspondingly progressively decreased. As a spring unwinds, as when a window sash is moved upwardly, the initial moment arm being at its minimum progressively increases so that the changing spring force, at all points in the vertical travel of the Window sash, either up or down, multiplied by the changing lengths of the moment arm remains substantially or approximately constant, and has at all times the same approximate ratio thereof to the weight of the window sash to which the balance is applied.

An understanding of the invention and of the embodiments which have been made and which have proven best for windows of heavy weight, those of intermediate Weight, and those of light weight, may be had from the following description, taken in connection with the accompanying drawing, in which,

Fig. l is a more or less diagrammatic view showing the use of one of the spring balances of my invention applied to a heavy weight window sash mounted for vertical movement in a window frame.

Fig. 2 is a like view showing two of such balances connected with the window sash.

Fig. 3 is an elevation of the interior structure of the sash balance used in Fig. l, with a side of the housing removed therefrom.

Fig. 4 is an elevation of a spring winding means used to give an initial preselected tension force to the spring.

Fig. 5 is a longitudinal vertical section, substantially on the plane of line 5-5 of Fig. 6 looking in the direction indicated.

Fig. 6 is a horizontal section, substantially on the plane of line (--6 of Fig. 5, said section being taken substantially inthe plane of the axes of the spring carrying drums.

Fig. 7v is a partial vertical section and elevation of a spring band balance of the type for use with light weight window sashes, the plane of the section being substantially on line 77 of Fig. 9.

Fig. 8 is a central vertical transverse section substantially on the plane of line 8-3 of Fig. 7.

Fig. 9. is a horizontal section and plan view, substantially on the plane of line 99 of Fig. 7.

Fig. 10 is a horizontal section, substantially on the plane of line 1010 of Fig. 11 of an embodiment of the invention which maybe used withwindow sashes of intermediate weights.

Fig. ll is a partial vertical section and elevation, the plane of the section being substantially on the plane of line 1111 of Fig. 10, and

Fig. 12 is a partial section and elevation of separated elements used for providing the spring carrying drums in the structure shown in Figs. 10 and 11.

Like reference characters refer to like parts in the different figures of the drawings.

The balance shown in- Figs. 5 and 6 is a balance for heavy duty, used in embodying my invention in serving heavy weight window sashes which usually are of metal, vertically slidable in metal frames. In structure, a housingis provided having a narrow elongated base 1 with spaced parallel vertical sides 2 extending upwardly from opposite longitudinal edges of the base, and with a covering member S closing the housing at the ends and top, The. housing made of sheet metal may be made in numerous waysof sheet metal parts whichwill be secure.- ly connected together when the balance is assembled.

Between the opposite sides 2 of the housing, two spaced horizontal shafts or arbors 4 and 5 are mounted and permanently secured at their ends. The shaft 5 has atclrum thereon consisting of'a central hub 6 (Fig. 6) located. around the shaft 5, a circular web 7 and a flange 8 which has two drum surfaces, the one of larger diameter' at 811 and of smaller diameter at 9, the cross sectional form of the drum. flange being fully shown in Fig. 6. Around the larger diameter portion 8a, a con- M secutive series of gear teeth'10 are provided integral with the drum and cut in a projecting rim at the inner open side of the drum.

The open side of the drum is closed by a closure member having a central hub 11 which telescopes over the hub 6, a web 12 parallel to the web 7 of the drum, which web has the same diameter as the diameter of the enlarged section 8a of said drum, and at the peripheral edges of which, a second continuous series of gear teeth 13 are made, the pitch diameter and the exterior diameter of the teeth and 13 being the same.

Within the drum a windable spring 14 of spring band material is mounted, its inner end being securely connected with the hub 11 and its outer end with the flange 8 of the drum described. It will be noted that the outer sides of the webs 7 and 12 are substantially close to the inner sides of the opposed sides 2 of the housing.

A second drum is mounted for turning about the axis of the shaft or arbor 4 (Fig. 6). It has a central hub 15 similar to the hub 6, a web 16 similar to web 7, and at the outer edges of the web 16, a flange having a relatively heavy body 17, and a smaller diameter cylindrical section 18 extending therefrom.

A closure for the open side of the last described drum includes a central hub 20 around the hub 15, and a web 21 similar to web 12. Gear teeth 22 meshing with the teeth 13 of the first described drum closure and of the same pitch diameter as the teeth 10 are formed around the periphery of such closure, a filling ring 19a is between section 8 and closure web 21 having gear teeth 19 at the periphery of the ring, which ring has a cylindrical section 19b inserted within the flange 17 of the second drum. Teeth 19 mesh with the teeth 10 as shown.

The heavier section 17 of the flange of said drum, at its outer side is provided with a helical or spiral groove 23 of progressively increasing diameter from one end to the other. Within the cylindrical section 19b, a spring 24, similar to the spring 14, and which is of spring ribbon stock and similar to clock main springs, has its outer end attached to the part 19b and the inner end secured to the hub 20.

A tape or cable 26 is secured at one end to the reduced diameter portion 18 of the last described drum which, at its outer end, leads therefrom downwardly through the bottom 1 of the housing as shown in Fig. 5. Such tape or cable wound around the drum in several layers or windings may be pulled out when a window sash to which connected is lowered and wound around the portion 18 when the sash is lifted.

The springs are given an initial force manually through the mechanism which is shown in Figs. 4 and 5. A gear 27 is in mesh with the teeth 13. It is at one end of a shaft, mounted horizontally for rotation on a supporting bracket 28, and may be manually actuated from below the bottom of the housing by turning a vertically positioned worm '29 rotatably mounted on the same bracket, the lower end of the worm 29 having a slot to receive a screwdriver. The bracket 28 is permanently secured at the upper side of the bottom 1 of the housing.

On turning the worm 29 to wind the springs, the web 12 is turned about the axis of shaft 5 and through the intermeshing engagement of the teeth 13 with teeth 22 web 21 is turned, thereby winding the spring 24 which will turn the member 19a, and through the teeth 19 thereon in mesh with the teeth 10, actuate the first described drum to wind the spring 14. Thus both springs are wound to an initial tension with the drum consisting of the parts 16 and 18 at rest and not moved by such initial spring winding. Of course at any time after the balance is installed, it may be further wound or unwound as conditions may require. The worm 29 and gear 27, which is of a worm tangent type, provide inherently a lock or stop against the springs unwinding after they have been wound to a desired point of tension.

A cable is connected at one end to the smaller diameter flange portion 8 of the first drum, is.wound around the surface 9 thereof in several turns and leads to the spiral groove 23 cut in the flange portion 17 of the second described drum. It is connected at its opposite end to such drum. When the tape or cable 26 is pulled outwardly on downward movement of a window sash to which the cable is attached, such second drum is turned in one direction and the first described drum is turned in the opposite direction, the cable unwinding from the first drum to the second drum and following the helical groove 23 as it is wound on to the second drum. In such down ward movement the forces of the springs 14 and 24 are increased. The cable 25 unwinds from the second described drum to the first, and when fully unwound is at the portion of the groove 23 which has the smallest radius.

The reverse occurs on lifting the sash, the springs unwinding and their forces aiding to lift the sash. The cable 25 is wound on to the first described drum from the second described drum, and because of the helical groove 23, the radial distance of the tangential points of contact of cable 25 from the center of the axis 4 of such described drum progressively increasing, reaching its maximum when the window sash is in upper position and the spring force correspondingly progressively decreased.

Two of the balances may be used in connection with a vertically slidable window sash mounted, one above and one toward each end of the upper horizontal window frame 30 (Fig. 2), the frame having spaced vertical side frame members 31 and the sash 32 slidable vertically between them. With two of the sash balances as described, the two tapes or cables 26 lead downwardly to the window sash, one at each side, and are connected thereto.

As shown in Fig. 1, one only of the sash balances may be mounted adjacent one end and above the upper horizontal cross member 30 of the window frame, the tape or cable 26 extending downwardly and connected at the adjacent side of the window 32. A second cable or tape 26a is wound within the tape or cable 26, and leads from the second described drum, which turns about the axis of the arbor 4, over the first drum outwardly and to and over an idle roller 32a near the opposite end of the frame member 30, and thence downwardly to the opposite side of the window sash 32. I

In either case when the sash is moved downwardly, the springs 14 and 24 are wound to increase their force, and the cable 25 is unwound from the helical groove 23 so that when the sash is at its lowermost position, the end of the cable 25 is nearest to the axis of the shaft 4, there taking place a progressive decrease in length of the moment arm through which the springs act. Their force is transmitted through the cable 25 initially to the second described drum rotatably mounted to turn about the shaft 4, and through the gearing connections described, the progressively increasing power of the springs 14 and 24 is substantially matched or balanced by a progressive decrease in the effective moment or lever arm through which the force is transmitted eventually to the tape or cable 26 attached to the window sash.

When the sash is lifted the reverse occurs, and while the force or power of the springs is progressively decreased, the lever arm or moment arm through which the forces act is progressively increased.

In Figs. 7' to 9 inclusive, a balance for a light weight window sash is shown. It includes a housing having a horizontal bottom 33, a vertical side 34 with which integral ends and top 35 may be formed, and a second spaced vertical side 36. A shaft or arbor 37 is mounted at its ends and extends between the vertical sides 34 and 36 (Fig. 8). A drum has a generally vertical web 38 rotatably mounted adjacent one end of the shaft 37 and against the vertical side 34, such web inclining upwardly and outwardly to provide a conical form, in

whicha continuous helical groove 39, similar to the previously described, cable receiving groove 23 is. cut or otherwise formed. The drum is completed by a cylindrical flange 40 reaching substantially to the opposite vertical side 36. A- sleeve 41 extends over the shaft 37 and, at its outerv end, has aninterlocking connection with the side 36. to hold such sleeve against rotation. A wound. band spring 42. has its inner end connected with the sleeve 41 and its outer end with the flange 40. A cable 43 issecured to theweb 38 of the drum, at the end of the groove'39 nearest the axis of the shaft 37 about which thedrum turns. Such cable 43 leads downwardly and outwardly to a change direction idle roller 44, which is rotatably andslidably mounted on a cross shaft 45 between the sides of the housing (Fig. 9). Such cable extends downwardly through an opening in the bottom 33 of the housing and, in use, is connected at one side and near the upper end of a vertically slidable shaft in a window frame, two of the balances being used in connection therewith, asin Fig. 2, for each of the window sashes in a window. frame.

In Fig. 7, the relative location of the cable 43 with respect to the groove39 in-which it lies is shown when a window sash is at its lowermost position. In such position the spring42 is wound to-have its maximum force or power, but the distance from the cable to the center of the-shaft 37 is at aminimum, therefore, the effective moment arm, which is such distance, is at a minimum, when the spring force is at its maximum. As the sash is lifted, the spring acts through the cable 43 to substantially balance the weight of the sash. With the decreasing force of the spring as it unwinds, the distance from where the cable acts on the drum progressively increases. Therefore, when the sash is lifted to its uppermost position, and the force of the spring is at its minimum, the moment or lever arm through which such force acts is at its maximum.

In Figs. to 12 inclusive, a third embodiment of the invention is shown which may be used for window sashes of intermediate weights between the light weight window sashes and the heavy window sashes. In this structure a housing similar to the housing shown in Fig. 1 is used, having spaced vertical sides 46 and 47, closed by the ends and top 48, all preferably of sheet metal. A shaft or arbor 50 is between the opposite sides of the housing, toward one end thereof, on which a drum is mounted having a hub 51, a web of generally conical form at the outer side of which a continuous helical groove 52, like the previously described grooves 23 and 39, is made, the drum being completed by an annular flange 53, around which the tape or cable 54 to extend therefrom through the bottom of the housing and connect with a window sash is wound. A second shaft or arbor 55, parallel to and in the same plane with the shaft 50, is mounted on and between the sides of the housing toward the other end thereof. Two drums are mounted to turn about such shaft. One of said drums has 'a hollow hub 59, a web 57 and a flange 58 (Fig. 12). The other has a hollow hub 59, a web 61 and a flange 61. The two hubs 56 and 59 telescope over the shaft 55 from opposite ends thereof, and the hubs coming together are provided, one with tongues, and one with slots (Fig. 12) so that they, are interlocked and rotate together.

A sleeve 62 covers both of said hubs and extends between the two webs 57 and 60. Said sleeve, substantially midway between its ends, has a continuous annular projection integral therewith extending outwardly which, preferably, is of 'a square outline, though it may be of any equivalent out-of-round shape. A gear 64 having a central opening to correspond with the shape of the projection 63 is located thereover between the two drums. A helically wound band spring 65, similar to the other clock type springs in previously described embodiments of the invention, have their inner ends secured to the sleeve 62. The outer ends of said springs are secured to the. flanges of. the respective. drums within which they are housed.

The springs may be initially wound to a desired tension, or may 'be wound or unwound after initial winding, by a worm shaft 66 which meshes with the gear 64, mounted for rotation on a bracket 67 between the drums, the bracket being secured to the bottom of the housing, as in Fig. 11. One end of the shaft 67 is slotted for screwdriver connection therewith to turn it, the slotted end of the shaft being accessible through an opening in the housing bottom.

A cable 68 wound around the flange 58 of one of said drums extends to and is connected to the web of, the drum having the helical groove 52 therein. In thisstructure, as in the others, with the tapes or cables 54 secured one at each side of a vertically slidable sash, as in Fig. 2, when the sash is lowered the springs are simultaneously wound to greater strength, and the point of tangential engagement of the tape or cable 54 with its drum moves progressively inward toward the central axis of the shaft 50 about which the drum turns. Conversely, when a shaft is lifted, the force of the springs is exerted through the cable tohelp in lifting the sash and substantially overcome the weight thereof. The springs in the drums progressively unwindand the radial distances of the continuously changing points of tangential engagement of the tape or cable 54 with the drum progressively increases, the same effect being produced as in the previously described structures.

It is to be understood that while the disclosure of the invention in its use has been in connection with sliding window sashes, and that such use with sliding window sashes is one of the primary places of use of the invention, it is not restricted thereto alone, but may be used in many other instances, as in balancing garage doors or other closures.

With the present invention, because of the generally constant value of the changing spring power multiplied by its changing lever or moment arm, the constant weight of a window sash is taken care of in a particularly simple, practical and useful manner. With progressive increase in spring strength and power there is a substantially progressive compensating decrease in the moment or lever arm through which the spring strength or power acts and vice versa. Therefore, a sash maybe raised and lowered far greater distances than in previous balances, wherein, in use, the weight of the sash is constant, but the progressively changing spring force or power, multiplied by a constant lever or moment arm, results in limiting the distance to which a sash can be successfully and practically raised and lowered. This was particularly the case with the heavy window sashes of large size and which, in practice, have the longest vertical distances of movement in opening and closing.

The invention is defined in the appended claims, and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. A balance for a window sash comprising, a housing having spaced vertical sides, two horizontally spaced shafts supported by and extending between the housing sides, a drum having a horizontal hub rotatively mounted on one of said shafts, a web of circular form connected with and extending vertically from the hub, and a cylindrical flange at the outer edges of the web, said web at its outer side having a helical groove with one end located inwardly from said flange and the other end adjacent the flange, said groove progressively increasing in radius from the first mentioned to the last mentioned ends of the groove, a tape wound on said flange, a second drum mounted on the second shaft having a hub, web and flange, a cable connected at one end with the first drum adjacent the outer end of said groove and to the second drum flange, windable on said last mentioned flange, and

ond drum, normally tending to rotate said second drum in a direction to wind the said cable onto the flange there- 'of, said spring means progressively decreasing in force, and resistingly yieldable to wind said cable into said groove of the first drum and unwind the tape therefrom, said spring means having increasing resisting force as the cable is wound into said groove due to the helical shape of the groove.

2. A balance for a window sash comprising a base, side walls attached to a longitudinal edge of the base, a pair of shafts having their ends fixed in said side walls, drums mounted on said shafts, sleeves on said shafts, springs 'fixed at one end to the interior of the drums and at the other ends to the said sleeves in a manner whereby rotation of the drums will tension the springs, one of said' drums having a surface having a helical groove of progressively changing diameter therein the other drum having a cylindrical portion, a cable attached at one end to one of the drums at the helical groove therein and at its other end to the said cylindrical portion of the other drum, whereby rotation of the first drum will cause rotation of the other drum, a sash cord attached to a cylindrical portion of the first drum and adapted to be wound on said cylindrical portion, the groove by virtue of the changing diameter thereof providing a power differential in the drive from one drum to the other.

3. A balance for a window sash comprising a base, a pair of spaced vertical side walls extending upwardly from opposite longitudinal edges of the base, two spaced horizontal shafts secured at their ends in said side walls, a drum having a horizontal hub rotatively mounted on one of said shafts, a circular web connected to said hub, a cylindrical flange at the outer edge of the web, said web having a helical groove at one side with a progressively changing radius, a second drum mounted on the other shaft, said drum having a hub web and flange, a cable connected at one end to the first drum adjacent the outer end of the helical groove and to the second drum flange and windable in said helical groove, coil springs within said drums and connected at one end to the interior of the drums and at the other end to the said hubs, manually operated means for simultaneously tensioning said springs, and a sash cable attached to and adapted to be wound on said first named drum.

References Cited in the file of this patent UNITED STATES PATENTS 479,150 Kimball July 19, 1892 820,962 Erb May 22, 1906 1,599,872 Braen Sept. 14, 1926 1,898,584 Mantz Feb. 21, 1933 2,679,659 Grupp June 1, 1954

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