Patent Abstract:
A method and apparatus for reducing the torque of a compound balance in order to substantially cancel out the torsional force of the torsion spring acting on the spiral rod by creating an equal and opposing torsional force on the extension spring. The apparatus is an assembly connector that is non-permanently engaged with the extension spring, with the spiral rod being tensioned by the torsional force of the torsion spring. Alternatively, the extension spring may be turned in a direction to apply more torque than is required for operation of the compound balance. It is then engaged with a non pre-tensioned spiral rod sub-assembly to transfer the excess torque to the torsion spring of the spiral rod sub-assembly. In this manner, the opposing torsional forces of the torsion spring and the extension spring acting on the spiral rod substantially cancel out each other.

Full Description:
REFERENCE TO RELATED APPLICATIONS 
     This application claims one or more inventions which were disclosed in Provisional Application No. 61/102,088, filed 2 Oct. 2008, entitled “APPARATUS AND METHOD FOR REDUCING TORQUE IN A COMPOUND BALANCE”. The benefit under 35 USC §119(e) of the United States provisional application is hereby claimed, and the aforementioned application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to the field of compound window balances. More particularly, the invention pertains to a device and method for connecting the extension spring of a compound balance to the torsion spring/spiral rod sub-assembly. 
     BACKGROUND OF THE INVENTION 
     Vertically sliding window assemblies are also known as hung windows and may consist of either a single sash or two sashes, respectively referred to as single hung or double hung windows. A hung window assembly generally includes a window frame, at least one sash, a pair of opposing window jambs, each jamb having a channel for allowing the vertical travel of each sash, and at least one window balance to assist with the raising and lowering of the sash to which it is attached by providing a force to counterbalance the weight of the sash. 
     Springs are utilized to provide the counterbalancing force and are especially useful for operating very heavy sashes. Compound balances are preferred for facilitating the operation of these very heavy sashes. In compound balances, a torsion spring provides a lifting force over the full travel of the sash through the jamb channel. The torsion spring force is converted into a lifting force by extending an elongated spiral rod. The torsion spring and elongated spiral rod are surrounded by an extension spring. Alternative designs have the sub-assembly encapsulated within a containment tube. It is desirable to have the combined axial forces of the torsion spring of the sub-assembly and extension spring provide substantially constant lifting force over the full vertical travel of the compound balance. The compound balance has an open end, from which the free end of the spiral rod extends, and a closed end, which is securely fastened to the wall of the jamb channel of the window frame. 
     The open end of the compound balance sub-assembly is often capped by a rotatable coupling having a central opening through which the elongated spiral rod extends. When the free end of the spiral rod is attached to a window sash, depending on the direction of vertical movement required to open the window, the spiral rod is either substantially fully extended or substantially fully retracted into the balance. In a double hung window design, the upper sash moves in a downward direction to open that portion of the window while the lower sash moves upwardly to open that respective portion of the window. 
     In tilting window sashes, the free end of the spiral rod connects to a shoe or carrier which traverses up and down the jamb channel of the window assembly with the sash. The window sash and window balance are linked together via a shoe or carrier. 
     Alternatively, the free end of the spiral rod may attach directly to the sash itself. In this case, a clip is securely attached to the end of the spiral rod. The conventional means of attaching the clip to the spiral rod includes the use of a rivet or an interference fit clip. 
     Especially with respect to windows having large, very heavy sashes, it is highly desirable to design a balance that provides the most lifting assistance. If the torsion spring exhibits too much torsional force, then the window operator must overcome the surplus frictional force caused by the torsional forces upon the carrier moving through the jamb channel. It is very desirable therefore to eliminate or substantially limit the amount of torque transferred from the compound balance to the connecting hardware. A reduction in the transfer of this torque lowers the lifting force required and therefore facilitates the raising and/or lowering of the sash. 
     SUMMARY OF THE INVENTION 
     An apparatus and method substantially canceling out the torsional force exerted on the spiral rod by the torsion spring so that the force on the spiral rod of a compound balance is substantially in a state of equilibrium and exhibits either no or very limited torque which would otherwise result in added frictional forces that increases the amount of energy needed to raise and lower the sash. 
     In embodiments of the present invention, an extension spring, co-axial with and surrounding the spiral rod sub-assembly is wound a number of turns to create a torque that opposes the torque imposed on the spiral rod by the torsion spring. The extension spring is preferably attached to the spiral rod either by an assembly connector attached to the end of the extension spring or a multi-angled series of bends in proximity to the end of the extension spring which provides for its attachment to the spiral rod by a pin or small rod. With the extension spring secured to the spiral rod, the extension spring is prohibited from unwinding when torque from the torsion spring of the spiral rod sub-assembly is applied. The attachment means functions to maintain the torsional force provided by the extension spring. This cancels out the torsional force of the torsion spring acting on the spiral rod with the opposing torsional force of the extension spring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  shows two cross-sectional views of a conventional compound balance inner sub-assembly, each view 90 degrees opposed from the other. 
         FIG. 1B  shows two cross-sectional views of the compound balance of the present disclosure where the extension spring encapsulates the inner sub-assembly. 
         FIG. 2A  shows an isometric view of an assembly connector in an embodiment of the present disclosure. 
         FIG. 2B  shows a side plan view of the assembly connector of  FIG. 2A . 
         FIG. 2C  shows an isometric view of the assembly connector of  FIG. 2A  having internally configured ramp elements for interaction with locking elements on the spiral rod. 
         FIG. 2D  shows a cross-sectional view of the assembly connector of  FIG. 2A  showing approximately one half of the segments of the internally configured ramp elements. 
         FIG. 3  shows an isometric view of an assembly connector having externally configured ramp elements. 
         FIG. 4A  shows an assembly connector, the spiral rod, and the extension spring secured to the assembly connector. 
         FIG. 4B  shows a cross-section of the assembly connector of  FIG. 4A  with elements of the spiral rod engaging the internally configured ramp elements of the assembly connector. 
         FIG. 5  shows an isometric view of an assembly connector with a lock. 
         FIG. 6  shows an isometric view of the assembly connector of  FIG. 5  separated from a progressively tapered internal sleeve located within the assembly connector. 
         FIG. 7  shows an isometric view of an assembly connector in which a slot rather than a round hole provides the opening through which the end of the spiral rod extends. 
         FIG. 8  shows a plan view of an assembly connector in which the end of the extension spring is configured to interact with a pin or small rod to connect the extension spring to the spiral rod. 
         FIG. 9  shows a plan view of the assembly connector of  FIG. 8  as viewed along line A-A of  FIG. 8 . 
         FIG. 10  shows an isometric view of the assembly connector of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1A , the inner sub-assembly of a conventional compound window (or sash) balance is shown in 90° opposed views. The combination of the spiral rod  10  and the torsion spring  14  are conventionally referred to as the “inner” sub-assembly  1 . It includes at least a spiral rod  10  having a first end  12  that extends from a first end  20  of the inner sub-assembly  1 . The spiral rod  10  is secured to a spiral shaped torsion spring  14  within the inner sub-assembly  1 . The torsion spring  14  may be either encapsulated by an optional containment tube  16  or it may remain non-encapsulated.  FIG. 1A  shows the sub-assembly encapsulated by a containment tube  16 . Nonetheless, whether a containment tube  16  is present or not, an extension spring  18  encapsulates either the containment tube  16 , if present, or the torsion spring  14  (see  FIG. 1B ) to form a compound balance  2 . In the present invention, the direction of the turns applied to the torsion spring  14  and the extension spring  18  are preferably opposite each other in order to provide the balance manufacturer with the ability to cancel out opposing torsional forces acting on the spiral rod  10 . The more these opposing forces are canceled out, the less friction exists within the window system and the more lifting assistance is provided to help the operator move the sash (not shown) either up or down. In conventional compound balances, there are no (counter torque) turns applied to the extension spring  18  to create an opposite torsional force that substantially cancels out the opposing torsional force of the torsion spring acting on the spiral rod  10 . 
     The first end  12  of the inner sub-assembly  1  extends out of the first end  20  of the compound balance  2 . The second end  22  of the inner sub-assembly  1  is non-permanently secured to an internal anchoring means  23 , as shown in  FIGS. 1A and 1B . The second end  22  of the compound balance  2  is firmly secured to a wall of the jamb channel (not shown) by means of a screw, rivet or locking pin inserted through hole  27 . As the first end  12  of the inner sub-assembly  1  is extended, the torsional force of the torsion spring  14  is transferred to the spiral rod  10 . Although the torsional force is intended to provide a progressively increasing axial force along the axis of the balance and the jamb channel of the window frame to retract the spiral rod  10  into the inner sub-assembly, thereby assisting the operator with the vertical movement of the sash, this torsional force also creates substantial friction, especially at the interface between the carrier to which the spiral rod is attached and the jamb channel of the window frame. This is counterproductive with respect to the goal of achieving easy movement of the sash. 
     In some embodiments of the present disclosure, an assembly connector  100 , as shown in several variations in  FIG. 2A  through  FIG. 7 , transfers the torsional force of the extension spring to the spiral rod. The assembly connector substantially alleviates the undesired transfer of the torsionally induced friction from the torsion spring of the inner sub-assembly  1  to other components of the window assembly. 
     These counterproductive torsionally induced frictional forces are substantially eliminated by use of the assembly connector  100  ( FIG. 2A-FIG .  7 ).  FIG. 2A  shows an isometric view of the assembly connector  100 . It includes an extension spring attachment portion  102 , a bore  104  through which the first end  12  of the spiral rod  10  extends, a hole  101  through which a spiral rod pin  24  (see  FIGS. 1A and 1B ) may be inserted, and an adjustment portion  106 . In  FIGS. 2A ,  5 ,  6  and  7 , the adjustment portion  106  is shown as being hexagonally shaped. However, any suitable geometric configuration may be used so long as it achieves the desired objective which is to provide a means to rotate or hold the assembly connector  100  while the extension spring  18  is being rotated. The unattached or first end  108  of the extension spring  18  is spun onto the threads of the extension spring attachment portion  102 , which can be designed to accommodate either a right or left hand turned extension spring. 
     In a method of assembling the first embodiment of the present invention, the spiral rod  10  is rotated, which creates a torsional force maintained by the torsion spring  14 . Then, the spiral rod  10  is allowed to retract into the inner sub-assembly  1  to be seated within the internal anchoring means  23  ( FIGS. 1A and 1B ) to prevent further rotation until the spiral rod  10  is extended during use. Next, a counter torque is applied to the extension spring  18  by turning it in a direction opposite from the direction of the turns applied to the spiral rod of the inner sub-assembly  1 . In one variation, the assembly connector  100  is attached to the extension spring  18  and the turns are then applied to the assembly connector  100 . In another variation, the turns on the extension spring  18  may be applied prior to engagement with the assembly connector  100 . The preferred means of attachment is by first securing the extension spring  18  onto the extension spring attachment portion  102  of the assembly connector  100 . This is preferably performed by turning or “screwing” the first end  108  of the extension spring  18  onto threads formed on the exterior of the extension spring attachment portion  102  (see  FIG. 4A ). 
     Another method of assembling the compound balance of the invention involves rotating the extension spring attachment portion  102  of the assembly connector  100  axially in a direction that is opposite from the pretension rotations applied to torsion spring  14 . The spiral rod pin  24  ( FIGS. 4B ,  5  and  6 ) is then inserted through hole  101  in the assembly connector  100  to maintain the torque applied to the extension spring  18 .  FIGS. 2A and 2B  show two locations for hole  101 . However, these images are provided to show alternate locations for this hole. Only one hole  101  is necessary to receive spiral rod pin  24 . 
     As noted earlier, a compound balance of the invention can be assembled with a non-pretensioned inner sub-assembly. In this case, the extension spring is turned to contain more torque than would be needed under normal operating conditions so that when the connector  100  is secured to the rod  10  by insertion of spiral rod pin  24  and the rod is disengaged from the pretension anchor  23 , the spiral rod  10  rotates, thereby winding the torsion spring  14  in an opposite direction from the turns applied to the extension spring  18  to a point where the torsional forces between the torsion spring  14  and the extension spring  18  substantially cancel out each other. In this manner, the excess torque of the extension spring  18  is transferred to the inner subassembly  1 , winding the torsion spring  14  until the opposing torsional forces of the extension spring and the torsion spring substantially cancel out the undesired torsional force acting on the spiral rod  10 . 
     Another method of assembling the compound balance involves rotating the extension spring attachment portion  102  of the assembly connector  100  axially in a direction that is opposite from the pretension rotations already applied to the spiral rod  10 . The assembly connector  100  is seated against the pin retaining portion  26  (see  FIGS. 2C and 2D ) via spiral rod pin  24 . The pin retaining portion  26 , best shown in  FIGS. 2C and 2D , includes two diametrically opposed hemi-spherically shaped ramps  28  that guide the spiral rod pin  24  to a seat portion  30 . Once the spiral rod pin  24  of the spiral rod  10  is secured within seat portion  30 , the torque applied to the extension spring  18  is maintained. If assembled properly, the pretension torque applied to the torsion spring  14  (by turning the spiral rod  10 ) is cancelled out by the torsional forces applied to the extension spring  18 . If further adjustment is necessary, due to the ease of moving the spiral rod pin along ramps  28 , the assembly connector  100  may be further turned until the opposing torsional forces between the torsion spring  14  of the inner sub-assembly  1  and that of the extension spring  18  are substantially cancelled out. 
     A first variation of the assembly connector  100  is shown in  FIG. 3 . The primary difference between the embodiment shown in  FIGS. 2A-2D  and that shown in  FIG. 3  is that the variation of  FIG. 3  shows the ramped pin retaining portion  26 ′ being located external to the main body of the assembly connector  100 . The spiral rod pin  24  is retained against seat portion  32 . Otherwise, the external ramped pin retaining portion  26 ′ embodiment of  FIG. 3  operates essentially the same as does the internal pin retaining portion  26  of the embodiment shown in  FIGS. 2C and 2D . 
     A second variation of the assembly connector  100  is shown in  FIGS. 5 and 6 . In this variation, a sleeve  34  is non-permanently interference fitted between the spiral rod  10  and the assembly connector  100 . Referring specifically to  FIG. 6 , the outer diameter of the sleeve  34  is tapered so that the outer diameter gradually decreases as it approaches the end  12  of the spiral rod  10 . The distal end (opposite the adjustment portion  106 ) of the assembly connector  100  contains at least one “paired” diametrically opposed “U” shaped notches  26 ″. The preferred number of “U” shaped notches is two, which, of course would engage only one spiral rod pin  24 . The increasing outer diameter of the sleeve  34  provides for a progressively increasing interference fit between the sleeve  34  and the inner diameter of the assembly connector  100 . The assembly connector  100  of this variation permits the non-permanent engagement between “U” shaped notches  26 ″ and the spiral rod pin  24  to maintain substantial equilibrium between the respective torsional forces of the torsion spring  14  and the extension spring  18 . 
     A slight modification of the assembly connector  100  of  FIGS. 2A-2D  is shown in  FIG. 7 . Referring back to  FIG. 5 , this embodiment of the assembly connector  100  exhibits a circular hole that allows for the easy passage therethrough of a spiral rod  10  containing rod pins  40 . These rod pins  40  are used for engagement with a hook or similar device for attachment to an edge of the window sash.  FIG. 7  shows a bore slot  38  designed to accommodate the size of the spiral rod  10  only. During assembly, the counter torque is first applied to the extension spring  18  and then the bore slot  38  of the assembly connector  100  is aligned with the spiral rod  10 . The assembly connector  100  is then allowed to slip over the spiral rod  10 . Of course, rod pins  40  must be installed onto the spiral rod  10  after the assembly connector  100  is installed onto the compound balance  2  because they will not fit through the bore slot  38 . Once all elements of the compound balance  2  are returned to their resting states, the torsional forces between the torsion spring  14  and the extension spring  18  substantially cancel out each other. 
     A second embodiment of the attachment means of the invention is shown in  FIGS. 8 ,  9  and  10 . It includes configuring the final windings  119 , which are located at the first end  108  of extension spring  18 , so as to create two “U” shaped seats, a first seat  126  and a second seat  126 ′ ( FIG. 10 ). These two seats are designed to retain a pin  124  that is secured to spiral rod  10 . When the torsional forces between the torsion spring (not shown in these Figures) and the extension spring  18  substantially cancel out each other, the pin  124  is inserted through a hole  128  in proximity to the first end  12  of the spiral rod  10  and the pin is then urged into the “U” shaped seats  126  and  126 ′. The pin  124  maintains continuity between the torsional forces of the torsion spring (via the spiral rod  10 ) and the torsional forces of the extension spring  18 . Now that the torsional forces of the torsion spring and the extension spring have substantially canceled out each other, the compound balance  2  may be installed into the jamb channel of a window frame. 
     Accordingly, it is to be understood that the embodiments of the invention herein described are merely illustrative of the application of the principles of the invention. Reference herein to details of the illustrated embodiments is not intended to limit the scope of the claims, which themselves recite those features regarded as essential to the invention.

Technology Classification (CPC): 8