Abstract:
Constant force springs are implemented to counterbalance adjustable height work surfaces cooperating with a substructure that further cooperates with open linear extension mechanisms and position retention mechanisms further cooperating with one or more bases. The methods include direct connecting the springs, and connecting the springs to one or more chains looping over one or more sprockets, the chains then connected to the substructure where methods to control the spring ends, and to address imbalances in the spring forces are included.

Description:
NOTE 
       [0001]    This application claims priority to U.S. 62/230,883 
     
    
     BACKGROUND 
       [0002]    Counterbalancing an adjustable height work surface using a long large diameter torsion spring was a commercial success decades ago in a drafting table, and has since seen many refinements to the technique. 
         [0003]    This did not expand into other applications significantly, and the advent of computer aided design fairly quickly replaced the drafting table. This was followed by efforts focused on ergonomic adjustments in the 1980&#39;s and &#39;90&#39;s. Adjustable height tables have various niche applications where the refined torsion spring counterbalancing saw competition from units with motorized lead screw drives linked to motion control circuitry and software, and very capable of movement with variable loads. 
         [0004]    With the release of some medical research in recent years there is some justification for a much broader adoption of sitting to standing adjustable height work surfaces. 
         [0005]    While motorized units have come down in price I believe there are applications that would welcome less costly counterbalanced units described herein. They require position retention mechanisms which are normally engaged; easily user disengaged, and can withstand considerable loads. 
         [0006]    One or more methods described herein could be used with inverted telescopic mechanisms and other open linear extension mechanisms, however, the methods herein show work surface substructures cooperating with open linear extension mechanisms, preferably mass produced drawer slides or slides, which appear to offer a lower cost approach enabling the potential health benefits to reach more people. 
       SUMMARY 
       [0007]    While motorized lifting has advantages, there are inherent costs that may be avoided by utilizing constant force springs to counterbalance the work surface and substructure that cooperates with known position retention methods that are normally engaged, and easily disengaged by one or both hands when changing the height. Social norms are leaning towards a healthy lifestyle, and low carbon footprints, where no motor may be an advantage. 
       Benefits 
       [0008]    There is a serious health reason for some, and a healthy reason for many to be using an adjustable height work surface that won&#39;t see wide adoption until products reach affordable levels. 
         [0009]    Counterbalancing with larger constant force springs is a light weight and relatively compact approach, and will last for 25,000 cycles. 
         [0010]    There are few moving parts and basically no electrical parts which improves reliability. 
         [0011]    Broad application potential, as the methods herein are compatible with movable and mobile configurations as well as desk, free standing, and wall mounted configurations. 
         [0012]    Fully functional in applications and locations where electricity may not be available or reliable. 
       Limitations 
       [0013]    The methods herein are limited to the implementations of constant force springs described as CF springs to provide a counterbalancing force equal to the weight of suitably equipped work surface and its cooperating elevated substructure enabling the user to easily and quickly manipulate its height. 
         [0014]    CF springs offer fixed forces, where auto-adjustable force methods, and motorized lifting capabilities have distinct advantages in some applications. 
         [0015]    To mitigate this limitation and better accommodate users, a stronger spring force is typically provided with the means to add ballast to counterbalance just the work surface, where the user can add preferred objects to the work surface and substructure, and remove ballast to re-balance. 
         [0016]    The user can also further upgrade the CF springs that are easy to replace. However, even with these capabilities, applications requiring frequent load adjustability would not be applicable. 
         [0017]    There is a risk of Overloading a work surface and then releasing its position retention system. A safety measure of providing 2 release mechanisms requiring the user to place both hands in a positions to hold the work surface is one option. Electrical circuits that sense overloads and lock the release mechanism are also known. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0018]    1.  FIG. 1 . Right rear ISO view of CF springs rotationally cooperating with the upper extents of base objects, and the extended CF spring directly cooperating with a substructure of an asymmetric work surface. 
           [0019]    2.  FIG. 2 . A left rear view of CF springs rotationally cooperating with the lower extents of the substructure, and the extended CF spring directly cooperating with the stationary base objects of an asymmetric work surface. 
           [0020]    3.  FIG. 2A  is a close up of substructure mounted springs. 
           [0021]    4.  FIG. 3 . A left rear view of the CF springs rotationally cooperating with the lower extents of the base objects, the extended CF springs cooperating through a coupling with flexible roller chain that cooperates with the substructure of an asymmetric work surface. 
           [0022]    5.  FIGS. 3 a , 3 b    are close-ups of exemplary method of constraining the coupling to a flexible object. 
           [0023]    6.  FIG. 4  An opposed pair of CF springs cooperating with the lower extents of the base objects, and further cooperating with a roller chain that cooperates with the substructure. 
           [0024]    7.  FIGS. 4 a , 4 b    are close-up views of upper connection to the chain, and the lower chain connection to the substructure. 
           [0025]    8.  FIG. 4 c    Additional components to support the opposed pair springs. 
           [0026]    9.  FIG. 5  The design of  FIG. 4  with added coupling orientation guides, a preferred method to address unequal force opposed pair CF springs. 
           [0027]    10.  FIG. 5 a    is a close up of the guided coupling, chain and sprocket. 
           [0028]    11.  FIG. 6 . is a rt. rear view of CF springs cooperating with a symmetric or free standing work surface substructure comprising spaced apart sub-assemblies cooperating through slides with base objects. A torsionally rigid shaft provides self-leveling. 
           [0029]    12.  FIG. 6 a    is a close up cutaway view of an exemplary removable CF spring installed in a base object. 
           [0030]    13.  FIG. 6 b    is an elevated Rt. Side view through the work surface for close up view  6   c.    
           [0031]    14.  FIG. 6 c    is a close up of cooperating objects connecting the CF spring to the substructure sub-assemblies on the right side of the sprocket. 
           [0032]    15.  FIG. 6 d   . identifies an inner structural support. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    While methods to incorporate constant force or CF spring counterbalancing within closed telescopic mechanism designs is possible, the methods herein are applicable to open linear extension mechanisms where the lower extents of the substructure is accessible at all elevations, and the springs are cooperating with a substructures in different locations not available or practical in some other substructures. However, by inverting the telescopic components, where the lower extents of the substructure is accessible does offer opportunities not covered herein. Some of the linear mechanisms cooperating with torsion spring lift assistance could also be adapted to the methods herein. 
         [0034]    The applications described herein are associated with a substructure cooperating with drawer slides or open linear extension mechanisms described as slides, but this should not be construed as limiting the scope of this description. 
         [0035]    Providing ways a user can compensate for a change in load is a desirable capability. This is accomplished by providing a greater counterbalancing force that cooperates with one or more containers of ballast that cooperate with the substructure or work surface to achieve counterbalance. This enables the user to add objects to the work surface and subtract ballast from the containers to regain desired counter balance. The user can also add additional CF springs to some substructures, and or swap these CF springs for higher force CF springs in all substructures. 
         [0036]    Each CF spring is constructed from thin sheet stainless steel in a range of thicknesses, and further formed and annealed into a coil spring in various diameters and widths. Smaller diameters of the same thickness provide higher forces but shorter life. Each CF spring coil has a free end that will extend out on a predictable larger radius for one quarter of a turn, and can then continue tangentially at that point on a linear path if the free end is constrained flat in the plane of travel. A distance of 1 diameter to preload the recoiling force is recommended. Higher forces are achievable by winding two or more coils on the same hub. Two or more hubs can work in parallel or as an opposing pair with one another. An opposing pair provides a method to neutralize end torsional deformation that each coil produces by positioning them to oppose one another. This is cost effective when connecting to a flexible object like roller chain, and the CF spring forces are matched. This is accomplished by aligning the free ends to extend together by connecting each opposing spring free end to one coupling causing these torsional forces to cancel each other. 
         [0037]    This free end torsional deformation causes deformation of the extended length of the spring if the free end features were simply connected to a chain, or other suitably flexible object where preferably a CF spring to chain coupling further cooperates with guides over its linear travel, the guides cooperating with the base manipulate the coupling by restraining it to a vertical orientation throughout its linear travel. An exemplary method of guiding the coupling is provided herein where methods requiring fewer components would be preferred. 
         [0038]    The first five implementations are illustrated on the back sides of an asymmetric work surface substructure where only the visible substructure back and side objects are identified. Utilizing CF springs for counterbalancing in other substructures only requires access to the lower extents of the movable substructure objects. 
         [0039]    The sixth implementation is a with symmetric work surface cooperating with 2 substructure sub-assemblies further cooperating with slides and 2 base structures. They are all preferred designs and depend on applications, anticipated loads, and other considerations. Connecting the free end of the CF springs directly to the substructure in the first two implementations are preferred for fewer parts and lower cost. 
         [0040]    A second method is connecting a flexible material, preferably roller chain to the CF spring that loops over a hub or sprocket to reverse the direction of the flexible material then connected to the lower extents of a substructure. Although more costly, its added benefit using chain with aligned and connected sprockets may be worth the expense. 
         [0041]    The opposed pair CF spring orientation is a third method that has an advantage of canceling the free end torsional forces with matched springs. 
         [0042]    The width of the substructure limits the number of CF spring coils that could be added to the first 2 methods assuming all other components are structurally capable. 
         [0043]    Single chain and sprocket designs with the opposed CF springs are examples where using belting or chord or other flexible material to substitute for the roller chain may present additional cost savings. 
         [0044]    However, aligned sprockets and chain designs of  FIGS. 3,6  enable the potential benefit of distributing imbalanced applied forces coming from either the CF springs or an imbalanced work surface load. To achieve this potential, an object or shaft connecting sprockets exhibits minimal torsional distortion to maintain sprocket alignment resulting in equal linear movement of the one or more substructures. This enables CF spring designs to utilize imbalanced CF spring loads without adverse consequences. 
         [0045]    Referring to  FIG. 1 , the substructure panel  13  cooperates with vertical objects  11 , 12  that further cooperate with drawer slides  30  that further cooperate with base objects  41 , 42  representing wall mounted, mobile chassis, or stationary base objects where additional structural base objects are not shown. A cross member  43  cooperates with the base objects  41 , 42  and further cooperates with one or more brackets  44  that further cooperate with one or more shafts  61  that rotationally cooperate with hubs  62  further comprising one or more parallel CF springs  63 . 
         [0046]    Bracket  44  may further comprise a second pair of shaft retention features  45 , that accommodate smaller diameter CF spring coils. All these shaft retention features preferably comprise an otherwise interfering feature that cooperates with slight cuts across the shafts to retain the shafts laterally (not shown). Other methods may be considered. 
         [0047]    The extended free ends  64  of the one or more CF springs comprising attachment features cooperate with stud features on bracket  45 , further comprising a clamping plate and nuts (not shown) to clamp the end of each spring, bracket  45  further cooperating with the lower extents of the substructure object  13  maintain the spring ends flat in the plane of travel. 
         [0048]    When the substructure is lowered to the sitting position as shown, the working extension of the CF springs is dimensionally equal to or greater than the maximum travel distance plus the CF spring preload distance to maintain a counterbalancing force throughout the range of vertical height positions of the substructure cooperating with the work surface  20 . This is true for all these implementations, where the travel distance becomes shorter with larger diameter springs but the life cycles increase significantly. 
         [0049]    Referring to  FIG. 2  the substructure panel  13  cooperates with vertical objects  11 , 12  that further cooperate with slides  30  that further cooperate with base objects  41 , 42  representing wall mount base objects as shown, or mobile or stationary chassis mounted base objects where additional structural base objects are not shown. The extended ends  64  of CF springs cooperate with studs connected to brackets  49  that are connected to cross-member  50  cooperating with the base objects  41 ,  42 . An additional feature  48  is a hole that would cooperate with a hand tool for ease of assembly or dis assembly of the preloaded springs and applies to all implementations described herein. Engaging or disengaging the CF springs in all these implementations is accomplished with the substructure fully extended 
         [0050]    Referring to  FIG. 2 a   , the lower extents of the substructure are modified to cooperate with brackets  47  further comprising slots  47   a  having a slight upward angle that retains one or more preloaded CF spring coils  63  and hubs  62  rotationally cooperating with shafts  61  that slideably engage and are captive within the slots  47   a  under load. 
         [0051]    Referring to  FIG. 3 , this implementation has more parts and cost, but also provides a self-leveling and load balancing capability that is maximized by positioning the CF springs and associated components further apart than shown, preferably proximate to the vertical objects  11 , 12 . The substructure panel  13  cooperates with vertical objects  11 , 12  that further cooperate with drawer slides (not visible) that further cooperate with base objects  41 , 42  common to all base structures. This example base structure comprises the pillar objects  41 , 42  that further cooperates with the legs  41   a ,  42   a , the added gusset  41   b , and cross members  77 ,  78 , and  51  representing a preferably mobile or stationary chassis base structures. Other base structural components are omitted. The cross member  51  further cooperates with two or more brackets  52  further comprising upwardly angled slots  53  providing retention features that cooperate with one or more parallel shafts  61  that rotationally cooperate with hubs  62  further comprising one or more CF springs  63 . 
         [0052]    The one or more CF spring extended free ends  64  cooperate with attachment features of the one or more couplings  65  that further cooperates with a clamping plate  76  retained by threaded fasteners. 
         [0053]    Referring to  FIGS. 3 a , 3 b   , the coupling  65  further comprises two spaced apart preferably pressed in stub shafts  72  on each sidewall cooperating rotationally with small idler wheels  73  that further cooperate with the insides of channel objects  74  that fixedly cooperate with upper and lower sets of bracket objects  75  further cooperating with cross members  77 , 78 . 
         [0054]    Couplings  65  further comprise attachment features  79  to cooperate with the first ends of one or more preferred roller chains  66  that loop over one or more sprockets  67  (shown without teeth). The sprockets do have teeth that are aligned and fixedly cooperate with a shaft  68  that rotationally cooperates with bracket  69  further cooperating with cross member  77  further cooperating with the base objects  41 , 42 . 
         [0055]    Referring to  FIG. 3 b   , the one or more roller chains loop over the aligned sprockets and extend downward where the second ends of the chains that may utilize master links to cooperate with features  70 , cooperating with a bracket  71  that further cooperates with the lower extents of the substructure. 
         [0056]    The fixed alignment of the sprockets  67  on the shaft  68  that is highly resistant to torsional loads, allows a stronger CF spring force urging one chain on one sprocket to communicate this greater force through the shaft to all other sprockets enabling dissimilar CF spring forces to act in unison, and eliminates any imbalance in the counterbalanced force applied to the substructure. 
         [0057]    When utilizing two or more CF spring coils, they may be positioned near the CG of the substructure as shown, or spaced further apart, preferably equidistant from the CG of the substructure, and preferably as far apart as practical. 
         [0058]    This low friction wheels in channels method may be configured on the sides of the springs as shown or on the front or back sides of the CF springs, and where a sliding fit between the coupling and the channel objects (shown in  FIG. 6 ) may be more economical, but would increase friction. The torsional force proximate to the end of the CF spring is quite strong, where increasing the vertical distance between the wheels or sliding points of contact would reduce the stresses. 
         [0059]    Other sliding or rolling features cooperating with fixed vertical objects can also be considered. Linear bearings or bushings retained by the coupling  65  cooperating with a vertical shaft would be another implementation. 
         [0060]    Referring to  FIG. 4, 4   a ,  4   b ,  4   c  the opposed pair of CF spring coils  63  neutralize the residual distortions when the extending ends  64  are fastened together, and cooperating with coupling  65  further comprising a feature  79  to connect the chain  66 , and a clamping plate  76  similar to those shown in  FIGS. 3 b , 4 a , 5 a   . This coupling should not require manipulation by guides as shown in these figures, provided the spring forces are balanced, and just cooperates with the first end of a roller chain  66  that loops over a sprocket  67  and downward to cooperate with object  70  cooperating with bracket  71  as shown in  FIG. 4 b    that further cooperates with the lower extents of the substructure. 
         [0061]    The sprocket  67  rotationally cooperates with a shaft  68  that cooperates with bracket  69  further cooperating with cross member  77  further cooperating with the base objects  41 , 42 . 
         [0062]    Referring to  FIG. 4C , the shafts  61  rotationally supporting each hub cooperating with the one or more CF springs are vertically retained by lower cross members  81 , 82  comprising pairs of level horizontal slots  83  that enable different size CF springs to be installed. Shaft collars  84  retain the shafts. 
         [0063]    Removing a cosmetic and safety panel provides access. Loosening the coupling fastener is recommended, then removing shaft retainers  84  on the rear side and applying firm downward palm pressure to the top of a CF spring coil allows the shaft to be removed toward the front, and releasing the coil slowly enables it to fully recoil. Removing the fasteners and the clamping plate from the coupling  65  enables the spring to be removed and replaced, by simply reversing this removal sequence. 
         [0064]    This arrangement is limited to matched pairs of CF springs, which is suitable for many applications. 
         [0065]    However, adding the guided coupling as shown in  FIGS. 3, 5  addresses the 10% spring force variations that might otherwise require sorting and matching, and the opportunity to mix CF spring force combinations in this product is beneficial. 
         [0066]    Referring to  FIGS. 5, 5   a , the bracket  69  cooperates with cross member  77  that further comprises an internal opening to accommodate the guided coupling  65  cooperate with clamping plates  76  (shown in  FIG. 3 b   ). The coupling further comprises a feature  79  to cooperate with the chain  66  using a master link preferably. 
         [0067]    The stud mounted wheels  73  are shown, but normally cooperating with channel object  74  that further comprise a bracket  75  cooperating with cross member  77 . The opposite channel object (not visible) is cooperating with bracket  69 . The channel objects  74  further cooperate with lower brackets  75  cooperating with the cross members  81 , 82 . 
         [0068]    Referring to  FIG. 6 , the CF springs counterbalance a symmetric work surface  20  and substructure cooperating with drawer slides, and can further cooperate with removable ballast. 
         [0069]    The Work surface cooperates with separated substructures  111 ,  112  that on their inside facing surfaces, cooperate with a load distributing object  113  shown in  FIG. 6C  preferred with some semi-rigid material choices for these objects  111 , 112 . The substructures  111 , 112  further cooperate with slide objects  31 , cooperating with slide objects  32 , that further cooperates with slide objects  33  that further cooperates with the narrow end surfaces of a base objects  41 ,  42  that are formed as an open channel shape in a horizontal cross section, and preferably wider at the base as shown. A cutaway of the side of base object  42  exposes the CF spring location. The same view would occur for either side of either base object. These base objects further cooperate rigidly with multi-directional feet (not shown) that would preferably comprise a connection between them along the floor. 
         [0070]    Referring to  FIG. 6A , The one or more CF springs  63  on each hub  62  rotationally cooperates with a shaft  61  retained in features of two sided bracket  85  that provides a handle  86  on one end and further comprises features  87  to pivotably cooperate with features  96  of the structural brace  88  (shown in  FIG. 6 d   ). An opening in the lower extents of the end surface of the base object  42  is normally covered by a structural cover plate (not shown) securely attached through the array of fastener clearance holes  89  to cooperate with threaded features in the structural brace  88  (shown in  FIG. 6 d   ). 
         [0071]    The pivotable bracket arms, or arms  85  are shown in the engaged position where the handle end  86  will further cooperate with one or more engaged latches (not shown) further cooperating with the base objects. Releasing the arm and pivoting it upward about sixty five degrees enables the CF spring to recoil its preload. The arms  85  would cooperate with a latching position retention (not shown). 
         [0072]    After removing the cover plate from the base object  42  end surface, and the fasteners retaining the clamping plate  76  to the coupling  65 , the free end of the CF spring is disconnected from the coupling. 
         [0073]    A previously described hand tool facilitates releasing the CF spring if needed. 
         [0074]    The arms  85  further comprise two pivoting shaft retention brackets  93  utilizing gravity to remain normally closed, the brackets: cooperate together, further comprise locking teeth  94 , and manual release levers  95 . Lifting either of these two pivotally connected levers  95  allows the shaft  61  cooperating with the CF spring  63  to drop nearly straight down. The curved ends of the lower shaft guides manipulate the falling CF spring by redirecting its downward momentum to a horizontal momentum urging the CF spring out the opening. 
         [0075]    Replacing the CF spring including the hub and shaft begins with a) insuring the arms  85  are latched up, b) sliding the spring through the opening and with one hand underneath, and c) lifting the spring up 3 inches, where the shaft  61  lifts the locking teeth  94  and gets retained behind these teeth. 
         [0076]    If needed, using the previously described small hook ended tool cooperating with feature  48  in the spring as described for  FIG. 2 , the free end of the CF spring is installed on the studs of the coupling followed by the clamping plate  76  and fasteners. After re-installing the cover plate, the bracket  85  is released and pivoted down to the horizontal position an securely latched in place. This pivoting down uncoils the CF spring to the preloaded condition as shown. 
         [0077]    The coupling  65  is guided in channels  74  that extend below their integral mounting bracket  75  features. The bracket  75  features are trimmed to allow access to the chain connection and the removable clamping plate  76 . 
         [0078]    Referring to  FIG. 6 b   , this elevated side view, identifies the work surface  20 , and the two substructures  111 , 112  cooperating with slide components  31  further cooperating with slide components  32  further cooperating with slide components  33 , that cooperate with the base objects  41 , 42  that further cooperate with multi-directional feet (not shown). The torsionally rigid shaft  166  is also shown. 
         [0079]    Referring to  FIG. 6 c   , added bracket  113  cooperates with substructure objects  111 ,  112  to communicate loads between objects  111 , 112  and cooperating mounting block  70  that further cooperates with the second ends of the chains  66  that loop over sprockets  67 , and continue down to the coupling position shown in  FIG. 6 a   . Object  113  also communicates loads to a position retention mechanism (not shown) located on the opposite side of base  42  from object  70 . 
         [0080]    Feature  91  is a cutout of the side wall of base object  42  to accommodate the chain and sprocket. 
         [0081]    Channel objects  74  with their integral mounting flanges  75  are visible. Other sliding fit or rolling fit guided coupling methods may reduce sliding friction and reduce costs. 
         [0082]    The sprocket  67  hides a shaft  68  extension on the far side that is preferably smaller in diameter than shaft  68  shown, and cooperates with a bushing cooperating with base  42 . 
         [0083]    Shaft  68  is shown to be a large diameter to emphasize the torsional stiffness required to provide minimal torsional deflection between two fixed and radially aligned sprockets over longer distances. The benefit of this known minimal torsional deflection technique is maintaining level motion, and distributing any excess force from one CF spring to both sprockets and both substructure objects, allowing uneven CF springs forces to cooperate without altering the preferred level motion. 
         [0084]    This minimal torsional deflection technique is known but not in cooperation with CF springs, or specifically to resolve imbalanced combinations of CF springs for counterbalancing work surfaces. 
         [0085]    Referring to  FIG. 6 d   , the braces  88  provides the additional structural support for the opening in the base object  42 , and the bracket pivot features  96 . 
         [0086]    Each brace  88  will comprise features to cooperate with a multi-directional foot to extend stability from the floor to the elevated work surface. 
         [0087]    Adding ballast to the asymmetric substructures can be accomplished with one or more containers of sand placed in the lower extents of the preferred substructure, where it is essentially hidden, or cooperating with the back side of object  13  in wall mounted configurations. The symmetric design of  FIG. 6 , with additional load capability would provide one or more methods to store ballast cooperating with the work surface underside, or the substructure sub-assemblies.