Spring counterbalance apparatus and method

Abstract

A spring counterbalance apparatus and method consists of a shade system with a torque profile, where the shade system is connected with a drive shaft. A first spring system is connected with the drive shaft where the first spring system is a standard wound spring system. A second spring system is connected with the drive shaft where the second spring system is a reverse wound spring system and where, in combination, the first spring system and the second spring system produce a counterbalance torque profile approximately equal to the shade system torque profile.

Claims

1. A spring counterbalance apparatus comprising: a shade system with a shade system torque profile, the shade system having a drive shaft; a first spring system connected with the drive shaft wherein the first spring system is a standard wound spring system having a spring storage spool and a spring drive spool; a second spring system connected with the drive shaft wherein the second spring system is a reverse wound spring system having a spring storage spool and a spring drive spool; wherein the shade is movable between an open position and a closed position; wherein in combination the first spring system and the second spring system produce a dynamic counterbalance torque profile because as the shade is lowered an increasing amount of the shade hangs from the head rail; wherein the dynamic counterbalance torque profile is slightly higher than the shade system torque profile; wherein in combination the standard wound spring of the first spring system and the reverse wound spring of the second spring system produce a dynamic counterbalance torque profile as the shade moves between the open position and the closed position; wherein when the shade moves between the open position and the closed position the dynamic counterbalance torque profile produced by the standard wound spring of the first spring system and the reverse wound spring of the second spring system closely approximate the dynamic weight profile of the shade thereby facilitating manual movement as well as motorized movement; wherein an axis of rotation of the spring drive spool of the first spring system and an axis of rotation of the spring drive spool of the second spring system are aligned; and wherein an axis of rotation of the spring storage spool of the first spring system and an axis of rotation of the spring storage spool of the second spring system are aligned.

2. The apparatus of claim 1 wherein the drive shaft extends through a spool of the first spring system and a spool of the second spring system.

3. The apparatus of claim 1 wherein a spool of the first spring system and a spool of the second spring system rotate upon an axis in alignment with the drive shaft.

4. The apparatus of claim 1 wherein the first spring system includes a spring with a first end and a second end wherein the first end is connected with the spring storage spool and the second end is connected with the spring drive spool and wherein the spring drive spool is connected with the drive shaft and wherein the second spring system includes a spring with a first end and a second end wherein the first end is connected with the spring storage spool and the second end is connected with the spring drive spool and wherein the spring drive spool is connected with the drive shaft.

5. The apparatus of claim 1 wherein a spring of the standard wound spring system and a spring of the reverse wound spring system have a width and the width is varied.

6. The apparatus of claim 1 wherein the standard wound spring system includes one or more springs selected from a group consisting of: constant gradient, negative gradient and positive gradient springs.

7. The apparatus of claim 1 wherein the reverse wound spring system includes one or more springs selected from a group consisting of: constant gradient, negative gradient and positive gradient springs.

8. The apparatus of claim 1 wherein the counterbalance torque profile is higher than the shade system torque profile and further including a removable bottom bar weight connected with the shade system.

9. The apparatus of claim 1 wherein the first spring system and the second spring system are connected to the drive shaft toward the middle of the drive shaft and away from the ends of the drive shaft.

10. A shade system comprising: a head rail; a shade connected to the head rail; a bottom bar connected to the shade; a drive shaft positioned in the head rail; the drive shaft having an axis of rotation; an electrically powered motor positioned in the head rail; the electrically powered motor operatively connected to the drive shaft such that operation of the electrically powered motor causes rotation of the drive shaft; a first spring system positioned in the head rail; the first spring system having a spring drive spool and a standard wound spring having a first end and a second end, the first end of the standard wound spring connected to the spring drive spool of the first spring system; a second spring system positioned in the head rail; the second spring system having a spring drive spool and a reverse wound spring having a first end and a second end, the first end of the reverse wound spring connected to the spring drive spool of the second spring system; wherein the shade is movable between an open position and a closed position; wherein when the shade moves between the open position and the closed position; the weight of the shade produces a dynamic weight profile because as the shade is lowered an increasing amount of the shade hangs from the headrail; wherein in combination the standard wound spring of the first spring system and the reverse wound spring of the second spring system produce a dynamic counterbalance torque profile as the shade moves between the open position and the closed position; wherein when the shade moves between the open position and the closed position the dynamic counterbalance torque profile produced by the standard wound spring of the first spring system and the reverse wound spring of the second spring system closely approximate the dynamic weight profile of the shade thereby facilitating manual movement as well as motorized movement.

11. The shade system of claim 10, wherein an axis of rotation of the electrically powered motor is aligned with the axis of rotation of the drive shaft.

12. The shade system of claim 10, wherein the first spring system and the second spring system are housed in a single spring housing.

13. The shade system of claim 10, wherein the shade system has a shade system torque profile and the dynamic counterbalance torque profile is approximately equal to the shade system torque profile.

14. The shade system of claim 10, wherein the shade system has a shade system torque profile and the dynamic counterbalance torque profile is slightly higher than the shade system torque profile.

15. The shade system of claim 10, wherein the second end of the standard wound spring of the first spring system is connected to a spring storage spool.

16. The shade system of claim 10, wherein the second end of the reverse wound spring of the second spring system is connected to a spring storage spool.

17. The shade system of claim 10, further comprising a third spring system positioned in the head rail, the third spring system having a spring drive spool having an axis of rotation and a standard wound spring having a first end and a second end, the first end of the standard wound spring connected to the spring drive spool of the third spring system.

18. The shade system of claim 10, further comprising a third spring system positioned in the head rail, the third spring system having a spring drive spool having an axis of rotation and a reverse wound spring having a first end and a second end, the first end of the reverse wound spring connected to the spring drive spool of the third spring system.

19. The shade system of claim 10, wherein the standard wound spring of the first spring system and the reverse wound spring of the second spring system are selected from the group consisting of positive gradient springs, constant gradient springs, and negative gradient springs.

20. The shade system of claim 10, wherein the standard wound spring of the first spring system and the reverse wound spring of the second spring system are coiled flat springs.

21. The shade system of claim 10, wherein the standard wound spring of the first spring system is preloaded, meaning the standard wound spring is pre-wound around the spring drive spool a predetermined number of revolutions.

22. The shade system of claim 10, wherein the reverse wound spring of the second spring system is preloaded, meaning the reverse wound spring is pre-wound around the spring drive spool a predetermined number of revolutions.

23. A shade system comprising: a head rail; a shade connected to the head rail; a bottom bar connected to the shade; a drive shaft positioned in the head rail; the drive shaft having an axis of rotation; a first spring system positioned in the head rail; the first spring system having a spring drive spool having an axis of rotation and a standard wound spring having a first end and a second end, the first end of the standard wound spring connected to the spring drive spool of the first spring system; a second spring system positioned in the head rail; the second spring system having a spring drive spool having an axis of rotation and a reverse wound spring having a first end and a second end, the first end of the reverse wound spring connected to the spring drive spool of the second spring system; wherein the shade is movable between an open position and a closed position; wherein when the shade moves between the open position and the closed position, the weight of the shade produces a dynamic weight profile because as the shade is lowered an increasing amount of the shade hangs from the headrail; wherein in combination the standard wound spring of the first spring system and the reverse wound spring of the second spring system produce a dynamic counterbalance torque profile as the shade moves between the open position and the closed position; wherein when the shade moves between the open position and the closed position the dynamic counterbalance torque profile produced by the standard wound spring of the first spring system and the reverse wound spring of the second spring system closely approximate the dynamic weight profile of the shade thereby facilitating manual movement as well as motorized movement; wherein at least one of the standard wound spring of the first spring system or the reverse wound spring of the second spring system is preloaded meaning at least a portion of the spring is pre-wound around the spring drive spool a predetermined number of revolutions.

24. The shade system of claim 23, wherein the predetermined number of revolutions is between two revolutions and forty two revolutions.

25. The shade system of claim 23, wherein the axis of rotation of the spring drive spool of the first spring system and the axis of rotation of the spring drive spool of the second spring system are aligned.

26. The shade system of claim 23, wherein the drive shaft extends through the drive spool of the first spring system and the drive spool of the second spring system.

27. The shade system of claim 23, wherein in combination the first spring system and the second spring system produce a counterbalance torque profile.

28. The shade system of claim 23, further comprising an electrically powered motor operatively connected to the drive shaft such that operation of the electrically powered motor causes rotation of the drive shaft.

29. The shade system of claim 23, wherein the first spring system and the second spring system are housed in a single spring housing.

30. The shade system of claim 23, wherein the second end of the standard wound spring of the first spring system is connected to a spring storage spool.

31. The shade system of claim 23, wherein the second end of the reverse wound spring of the second spring system is connected to a spring storage spool.

32. The shade system of claim 23, further comprising a third spring system positioned in the head rail, the third spring system having a spring drive spool and a standard wound spring having a first end and a second end, the first end of the standard wound spring connected to the spring drive spool of third spring system.

33. The shade system of claim 23, further comprising a third spring system positioned in the head rail, the third spring system having a spring drive spool and a reverse wound spring having a first end and a second end, the first end of the reverse wound spring connected to the spring drive spool of the third spring system.

34. The shade system of claim 23, wherein the standard wound spring of the first spring system and the reverse wound spring of the second spring system are selected from the group consisting of positive gradient springs, constant gradient springs, and negative gradient springs.

35. The shade system of claim 23, wherein the standard wound spring of the first spring system and the reverse wound spring of the second spring system are coiled flat springs.

36. A method of operating a shade system, the steps comprising: providing a head rail having shade connected to the head rail and a drive shaft positioned in the head rail; positioning a first spring system having a standard wound spring in the head rail and operatively connecting the first spring system to the drive shaft; positioning a second spring system having a reverse wound spring in the head rail and operatively connecting the second spring system to the drive shaft; positioning an electrically powered motor in the head rail and operatively connecting the electrically powered motor to the drive shaft; activating the electrically powered motor such that operation of the electrically powered motor causes rotation of the drive shaft; wherein the shade is movable between an open position and a closed position; wherein when the shade moves between the open position and the closed position, the weight of the shade produces a dynamic weight profile because as the shade is lowered an increasing amount of the shade hangs from the head rail; wherein in combination the standard wound spring of the first spring system and the reverse wound spring of the second spring system produce a dynamic counterbalance torque profile as the shade moves between the open position and the closed position; wherein when the shade moves between the open position and the closed position the dynamic counterbalance torque profile produced by the standard wound spring of the first spring system and the reverse wound spring of the second spring system closely approximate the dynamic weight profile of the shade thereby facilitating manual movement as well as motorized movement.

37. The shade system of claim 36, wherein the first spring system and the second spring system are housed in a single spring housing.

38. The shade system of claim 36, wherein the first spring system is housed in a first spring housing, and the second spring system is housed in a second spring housing separate from the first spring housing.

Description

DESCRIPTION OF THE DRAWINGS

(1) Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiment, the appended claims and the accompanying drawings in which:

(2) FIG. 1 is a perspective view of a Prior Art shade system with shade extended;

(3) FIG. 2 is a graph illustrating the shade system torque profile of the shade system of FIG. 1 and a counterbalance torque profile;

(4) FIG. 3 is a perspective view of the spring counterbalance apparatus of the present invention connected with a shade system in a prior art location at the end of the drive shaft;

(5) FIG. 4 is a perspective view of the invention of FIG. 3 showing the spring counterbalance apparatus located near the middle of the drive shaft away from the ends of the drive shaft;

(6) FIG. 5A illustrates a reverse wound spring system according to the invention and FIG. 5B illustrates a standard wound spring system according to the present invention;

(7) FIG. 6 is an exploded view of the invention according to FIG. 4;

(8) FIG. 7 is a close up exploded view of the invention of FIG. 6; and

(9) FIG. 8 is a schematic showing the combination of standard wound and reverse wound spring systems of the invention of FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

(10) The preferred embodiment of the present invention is illustrated by way of example in FIGS. 1-8. With specific reference to FIGS. 1 and 2, spring counterbalance apparatus 10 is disclosed with reference to a shade system 12. Shade system 12 includes head rail 14 and head rail cover 16. Shade system 12 also includes architectural opening cover, shade 18. Shade system 12 typically includes a bottom bar 20 designed to make contact with a window sill, not shown, for example only, so as to ensure a uniform contact with the sill. Bottom bar 20 also adds weight to the unattached end of shade 18 as may be useful according to the present invention as will be described more fully hereafter. All these elements of the invention are known in the art and not described more fully hereafter except to note that the shade 18 may be any form, cellular as shown, slat, Venetian blind or the like.

(11) FIG. 2 is a graph showing the shade system torque profile 22 for shade system 12. All the elements of the shade system 12 that contribute to the weight of the shade 18 that must be raised and lowered contribute to a shade system torque profile 22 that is unique for each shade system 12. Shade system torque profile 22 is a negative gradient profile with the highest torque requirements imposed when the shade is extended and reducing as revolutions increase and the shade 18 is raised.

(12) FIG. 2 also illustrates a counterbalance torque profile 24 in dotted lines. Counterbalance torque profile 24, in this example, has been created, as will be more fully described hereafter, with a higher nominal torque than the shade system torque profile 22. It should be understood that the present invention enables a counterbalance torque profile 24 to be created that matches or nearly matches and is approximately equal to the shade system torque profile 22. However, according to one aspect of the invention, it is just as easily possible to create the slightly higher counterbalance torque profile 24 illustrated in FIG. 2 to extend the operating life of the system. That is, over time, due to material fatigue, stress relaxation, etc. in the springs, the torque generated from the counterbalance is reduced. If the counterbalance torque profile 24 is initially designed to exactly match the shade system torque profile 22, the counterbalance would lose the ability to provide sufficient torque to counteract the torque of the shade system 12. So, by creating a higher nominal counterbalance torque profile 24, a small amount of weight, such as bottom bar 20 or the like, may be added to the shade 18 to balance the torque profiles exactly. As the counterbalance begins to fatigue, a user can simply remove the added bottom bar 20 weight and thereby extend the useful life of the counterbalance system. It should be understood that the use of the spring counterbalance apparatus 10 in this manner is only an option that is available because the invention enables creation of specific desired counterbalance torque profiles 24 as more fully described hereafter.

(13) Referring now to FIGS. 3 and 4, partial perspective views of the invention of FIG. 1 are shown with the head rail 14 and head rail cover 16 removed to show suspension cords 26 (in dotted lines). Suspension cords 26 are connected with shade 18 with one end (not shown) connected at the bottom of shade 18 as at bottom bar 20 and the other end connected with suspension cord housings 28. Suspension cord housings 28 are connected with drive shaft 30. Drive shaft 30 is connected with motor 32 and motor 32 is connected with power supply 34 as, for example only, batteries 36. Operation of the motor 32 moves drive shaft 30 in one direction or the other such that suspension cord housings 28 move and either wind suspension cords 26 onto or off of suspension cord housings 28. Without a counterbalance, motor 32 and power supply 34 must be sufficient alone to effect the movement of the shade 18.

(14) FIG. 3 illustrates a spring counterbalance 38 connected as with all prior art systems known to the Applicants at one end of the drive shaft 30. While the system may function in this location, according to one aspect of the invention, spring counterbalance 38 is preferably located at the middle area of drive shaft 30 away from the ends of the drive shaft 30 as shown in FIG. 3. This location, Applicants have determined greatly reduces torsion on the drive shaft 30, helps suspend it and reduces wear, tear and noise due to operation.

(15) Referring now to FIGS. 5A and 5B, spring counterbalance 38 is shown to be composed of a combination of spring systems 40. Spring system 40 includes a spring storage spool 42 and a spring drive spool 44 and a spring 46. One end of spring 46, preferably a flat spring, is connected with spring storage spool 42 and the other end of spring 46 is connected with spring drive spool 42 Importantly, FIG. 5A shows a reverse wound spring system 48 in which spring 46 is connected with the top of spring drive spool 44 and the bottom of spring storage spool 42. Conversely, FIG. 5B shows a standard wound spring system 50 in which spring 46 is connected with the bottom of spring drive spool 44 and the top of spring storage spool 42. If the standard wound spring system 50 and the reverse wound spring system 48 are constant torque springs, for example only, they would cancel each other out and have no effect on the shade system torque profile 22. However, by mixing various spring systems 40, reverse wound 48 and standard wound 50, Applicants have enabled a user to create a limitless range of counterbalance torque profiles 24.

(16) Referring now to FIGS. 6 and 7, spring counterbalance 38 spring system 40, consisting of multiple spring storage spools 42 and spring drive spools 44, is shown in spring housing 52. Importantly, spring drive spools 44 are connected with drive shaft 30. Spring housing 52 may be a single housing encompassing all the spring systems 40 as more clearly shown in FIG. 7. It also may be that spring housing 52 encloses each individual spring system 40 or that more than one spring housing 52 is provided.

(17) FIGS. 7 and 8 illustrate a spring counterbalance 38 made up of multiple spring systems 40 that create a desired counterbalance torque profile. As illustrated, for example only and not by way of limitation, this particular spring counterbalance 38 includes two negative gradient standard wound spring systems 50 labeled A; one preloaded negative gradient standard wound spring system 50 labeled B; and one negative gradient reverse wound spring system 48 labeled C. The result is a spring counterbalance apparatus 10 that matches or nearly matches the torque exerted on the drive shaft 30 by suspension cords 26, bottom bar 20, etc. such that the combined torque will approach zero.

(18) The Applicants have found that the present invention is extraordinarily flexible in particular when a full variety of torque gradient springs are accessed. That is, not only negative gradient springs are used. Also used or available are constant gradient and positive gradient springs. Thus, the invention includes standard wound spring systems 50 utilizing negative, positive and constant gradient springs and reverse wound spring systems 48 also utilizing negative, positive and constant gradient springs. Still further, Applicants have found that the width of the springs 46 provides another measure of flexibility. Making the springs 46 wider or narrower, it has been determined, also affects the torque profile.

(19) As indicated above with regard to FIGS. 7 and 8, Applicants have determined that the use of preloaded springs also enhances the ability of the apparatus to match required shade system torque forces. The term preloaded as used herein is understood by noting that the force generated by any spring is a function of displacement. In the case of coiled flat springs (power/clock springs and constant torque springs for example), depending on length and spring drive spool/arbor diameter, there is a maximum number of revolutions, or displacement, that the coiled flat spring can provide as it is being wound onto the spring drive spool/arbor. In any case, as long as the spring is wound onto the spring drive spool/arbor less than the maximum allowable displacement, the spring will provide a torque (in the case for a window covering where a spring drive spool/arbor is connected to a drive shaft for example). The nominal amount of torque available is a direct function of the displacement of the spring on the spring drive spool/arbor. For example, a positive gradient spring will provide a torque that increases with displacement, a negative gradient spring will provide a torque that decreases with displacement, and a constant gradient spring will provide a torque that remains constant, or mostly constant, with displacement. For clarification, again, a standard wound system provides a counterclockwise, or positive, torque, and a reverse wound system provides a clockwise, or negative, torque. Also, the term output drum will be used in place of spring drive spool/arbor.

(20) With a basic understanding of a coiled flat spring from the explanation above, the following three springs are used for example to further describe the term pre-loading:

(21) 1. Constant Gradient Spring a. Max Displacement: 42 Revolutions b. Torque Range: 3 in-oz. @ 2 Revolutions-3 in-oz. @ 42 Revolutions 2. Negative Gradient Spring a. Max Displacement: 42 Revolutions b. Torque Range: 7 in-oz. @ 2 Revolutions-3 in-oz. @ 42 Revolutions 3. Positive Gradient Spring a. Max Displacement: 42 Revolutions b. Torque Range: 3 in-oz. @ 2 Revolutions-7 in-oz. @ 42 Revolutions

(22) A spring's nominal range of torque values is dependent on material, width, thickness, natural spring radius, and output drum diameter. The present invention recognizes that any variation in these parameters can be used to create an ideal counterbalance system.

(23) By way of example, along with these three springs being considered, it is assumed that a window covering requires the drive shaft to rotate twenty revolutions in order to fully operate. The function of pre-loading is to shift the range of torque values used by each spring. Since the window covering only requires twenty revolutions, the first twenty revolutions of a spring, the last twenty revolutions of a spring, or any range of twenty revolutions in between may be pre-loaded. For example, if the following ranges of twenty revolutions for a standard wound system are considered: a. 2-22 Revolutions b. 12-32 Revolutions c. 22-42 Revolutions
It is found that the three springs provide the following torque ranges: 1. Constant Gradient Spring a. Torque Range: 3 in-oz. @ 2 Revolutions-3 in-oz. @ 22 Revolutions b. Torque Range: 3 in-oz. @ 12 Revolutions-3 in-oz. @ 32 Revolutions c. Torque Range: 3 in-oz. @ 22 Revolutions-3 in-oz. @ 42 Revolutions 2. Negative Gradient Spring a. Torque Range: 7 in-oz. @ 2 Revolutions-5 in-oz. @ 22 Revolutions b. Torque Range: 6 in-oz. @ 12 Revolutions-4 in-oz. @ 32 Revolutions c. Torque Range: 5 in-oz. @ 22 Revolutions-3 in-oz. @ 42 Revolutions 3. Positive Gradient Spring a. Torque Range: 3 in-oz. @ 2 Revolutions-5 in-oz. @ 22 Revolutions b. Torque Range: 4 in-oz. @ 12 Revolutions-6 in-oz. @ 32 Revolutions c. Torque Range: 5 in-oz. @ 22 Revolutions-7 in-oz. @ 42 Revolutions
Note, the previous torque ranges are for a standard wound system. A reverse wound system would provide the identical negative nominal torque ranges.
Thus, several of the same type, or gradient, of spring with the same preload may be used and/or several of different types, or gradient, of spring where each spring has a different preload, and/or any variation in between to create the ideal counterbalance system. Moreover, when this same preload concept is used in conjunction with the present invention where at least one standard wound system is combined with at least one reverse wound system, the range of achievable torque gradients and nominal ranges, without the addition of excessive bottom bar weight, to create the ideal counterbalance system is virtually limitless.

(24) Another important aspect of the invention is that positioning of the shade 18 may be done by hand, manually. Applicants have observed that the motorized prior art systems can not be grasped by hand and moved to a desired location without having to disconnect motors, gears, etc. or when moved will not stay in the new location The spring counterbalance apparatus and method 10 of the present invention has the unique advantage of enabling simple hand location without changing, altering or removing elements of the system. It is an advantageous result of the structure of the invention that the combined spring systems 40 assist movement when moved and, yet, resist movement when stopped and which, therefore, stay in place after movement either mechanically by the motor 32 or manually.

(25) In summary, a user determines the shade system torque profile 22 and then matches it with a counterbalance torque profile 24 created from a combination of at least one standard wound spring system 50 and at least one reverse wound spring system 48 assembled from negative, positive or constant gradient springs of the same or different widths and possibly some prewound, preloaded, springs as well.

(26) The description of the present embodiments of the invention has been presented for purposes of illustration, but is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. As such, while the present invention has been disclosed in connection with an embodiment thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention as defined by the following claims.