Abstract:
A curl spring sash shoe cassette improves upon the suggestions of U.S. Pat. Nos.  5,353,548  and  5,463,793  by providing a mounting bracket that holds an uncurled length of the curl spring and is securely mounted on top of the shoe cassette to maintain an assembly of the shoe body, the curl spring, and the mount during shipment to a window manufacturer. The mount can receive two mounting screws to resist torque caused by curl springs and sash weight. The shoe is also improved to facilitate removal and reinsertion of sash pins into the tilt lock cams of the shoes and ensure that shoe body halves do not rotate relative to each other when sash tilting splays the body halves apart to lock them in a shoe channel.

Description:
FIELD OF THE INVENTION 
       [0001]    Counterbalance systems for vertically movable window sash. 
       BACKGROUND 
       [0002]    This invention improves on a locking shoe and mounting bracket usable with a curl spring window balance system such as explained in U.S. Pat. Nos. 5,353,548, and 5,463,793. The invention adds convenience and reliability to the proposals of those patents. 
       SUMMARY 
       [0003]    The improvements made by this invention include a mounting bracket that can hold its position while being shipped with a shoe cassette holding a curl spring and yet can automatically disengage from the spring shoe when fastened to a sash jamb channel. The shoe cassettes are also preferably formed of identical halves that are unhanded so that a shoe cassette can be deployed on either side of a window sash. The cassette halves are preferably configured to resist relative rotation as they are splayed apart in response to cam action of a tilt lock cam contained within the shoe. The tilt lock cams can be configured to retain headed sash pins, or can have recesses or slots that allow a sash pin to extend more than half way through a locking cam. The improved system also allows locking pads to be inexpensively installed on the shoes to exert increased locking friction when a sash tilts and shoe cams lock the shoes in their channels. 
     
    
     
       DRAWINGS 
         [0004]      FIG. 1  is an isometric view of a shoe cassette including a curl spring, a spring mount, and a sash pin to counter balance one side of a window sash. 
           [0005]      FIG. 2  is an isometric view of a shoe cassette, including a curl spring, a spring mount, and optional locking pads to counter balance an opposite side of a window sash. 
           [0006]      FIG. 3  is a fragmentary view of an upper region of the cassette of  FIG. 2  omitting a curl spring to help illustrate a preferred configuration of shoe mount. 
           [0007]      FIG. 4  is a fragmentary cross-sectional top view of the shoe cassette of  FIG. 2  partially mounted within a shoe channel of a window jamb to illustrate how the shoe mount (in solid black) clears a tilt latch of a sash. 
           [0008]      FIG. 5  is a fragmentary rear view of the mounting bracket and the top of the shoe cassette of  FIG. 2  to illustrate how the mounting bracket mounts on the shoe body. 
           [0009]      FIG. 6  is an exploded isometric view of the cassette of  FIG. 2  showing a curl spring, locking cam, and shoe halves, without a spring mount. 
           [0010]      FIG. 7  is an exploded isometric view reversed from the view of  FIG. 6  to show that each shoe half includes a rotation resisting projection and recess, and also showing a tilt lock cam with a through channel that can receive a sash pin extending more than half-way through the cam. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    Shoe cartridges or cassettes  10 , such as illustrated in  FIGS. 1 ,  2 ,  6  and  7 , include shoe bodies  11  that contain curl springs  30  and locking cams  20 . Shoe bodies  11  are preferably molded in halves  11   a  and  11   b  that are identical and that fit together in an interlock allowing a lower region of the shoe bodies to expand or splay apart in response to rotation of locking cam  20 . Shoe body halves  11   a  and  11   b  are preferably interconnected at their upper regions by a pair of headed rails or ridges that are formed on each of the body halves to slide into an interconnect with the opposite body half. 
         [0012]    An upper edge or top region  12  of shoe body  11  supports mounting bracket  50 . A short length of curl spring  30  is uncurled from shoe body  11  and is attached to mounting bracket  50 , which can hold the assembled shoe body  11 , curl spring  30 , and mounting bracket  50  together for assembly into a window or shipment to a window manufacturer. 
         [0013]    Mounting bracket  50  improves on a simpler bracket suggested in the &#39;548 and &#39;793 patents. Bracket  50  is robust enough, and well enough braced and interlocked at the top  12  of shoe body  11 , to hold itself and curl spring  30  in place in an assembled cassette  10  during shipment. This provides the convenience to a window manufacturer of shoe cassettes arriving assembled with mounting bracket  50  ready to secure each cartridge in a shoe channel of a window jamb. All that is necessary is to slide each cassette into a shoe channel to the mount position, and then drive in one or two fastening screws  51  to fasten mount  50  in place. Two fasteners or mounting screws  51  are preferred so that mount  50  can resist a torque or turning force applied by curl spring  30 . In some jamb channels, mount  50  can be blocked from rotation by channel walls, making a single mounting screw  51  all that is necessary for securely holding mount  50  in place. 
         [0014]    To accomplish its improvements, mounting bracket  50  preferably includes mounting wall  52 , spring holding wall  53 , and brace  55 , as best shown in  FIGS. 3 ,  4  and  5 . Mounting wall  52  is preferably flat so that it can be fastened snuggly against back wall  61  of shoe channel  60 . Mounting wall  52  also includes a hole  56  or a hole  56  and a slot  57  to receive one or two mounting screws  51 . Spring holding wall  53  includes a projection  54  oriented to fit into an opening  34  in curl spring  30 , which exerts a downward pull on mounting bracket  50  to hold spring  30 , mount  50 , and body  11  in the assembled position illustrated in  FIGS. 1 and 2 . Spring connecting wall  53  is preferably normal or perpendicular to mounting wall  52 , and brace  55  preferably extends normal or perpendicular to spring holding wall  53  and parallel with mounting wall  55 . The interrelationship between walls  52  and  53  and brace  55  cooperates with the downward bias of spring  30 , to securely support mount  50  on the top  12  of shoe body  11 . 
         [0015]    The top or upper surface  12  of shoe body halves  11   a  and  b  preferably include headed ridge or “dog bone” shaped connectors  13  that hold shoe body halves  11   a  and  b  together in proper alignment. Connectors  13  also allow a superposed attachment of an additional curl spring container mounted on top of shoe body  11 . The headed rail connectors also provide a sturdy interlock with mount  50 , as shown in  FIG. 5 . 
         [0016]    Mounting wall  52  preferably has an opposed pair of projections  57  that extend under headed connectors  13  to prevent mount  50  from pivoting out of its position on the top  12  of body  11 . The projection  57  that is farthest from spring holding wall  53  is especially well positioned to prevent this. Spring holding wall  53  has a downwardly extending projection  58  that overlaps with the adjacent dog bone connector  13 . Brace  55  rests on top of a connector  13 , and has a projection  59  ( FIGS. 1-3 ) that hooks over an edge of the connector  13  on which it rests. All these features ensure that mount  50  stays reliably in place on top of shoe body  11 , especially when curl spring  30  provides a downward force pulling mount  50  downward against the top of shoe body  11 . 
         [0017]    Headed rail connectors  13  have end notches  14  that allow mount projections  57  to escape from under connectors  13  when mounting wall  52  is fully attached flat against back wall  61  of shoe channel  60 . In the position of mounting bracket  50  as illustrated in  FIG. 4 , mounting screw  51  has not been tightened enough to draw mounting bracket  50  snugly against back wall  61  of shoe channel  60  so that mounting bracket  50  has not yet escaped from shoe body  11  via notches  14  in the ends of connector rails  13 . Tightening screw  51  beyond the position illustrated in  FIG. 4  to draw mounting wall  52  snugly against panel wall  61  then moves projections  57  into notches  14  of connectors  13 , which allows mount  50  to escape or separate from the top  12  of shoe body  11 . In practice, this separation occurs when shoe body  11  is pulled downward after mount  50  is fully secured within channel  60 . In effect, the sturdy interlock between mount  50  and shoe body  11  that allows shipment of assembled cassettes as illustrated in  FIGS. 1 and 2  also automatically disconnects mount  50  from cassette body  11  when mount  50  is fully secured in place in a shoe channel  60 . 
         [0018]    Since mount  50  is preferably free to slide along top surface of shoe body  11  when fastened into a shoe channel, as described, it is desirable to allow relative movement between curl spring  30  and spring holding projection  54 . Relative movement at the interconnection between spring  30  and projection  54  allows mount  50  to slide into mounted position without pulling spring  30  laterally out of its alignment with shoe body  11 . A preferred way of accomplishing such relative movement is to make hole  34  in spring  30  an oval or oblong hole or slot, as best shown in  FIGS. 6 and 7 . Projection  54  can then move laterally within oblong hole or slot  34  to leave spring  30  in its aligned position relative to body  11  while mount  50  slides laterally into a released position engaging wall  61  of a shoe channel. 
         [0019]    As best shown in  FIG. 6 , locking cam  20  preferably has sash pin channels or slots  22  arranged on opposite sides of an annular cam  21 . Each of the cam slots  22  preferably has in turned walls  23  that can capture a head  73  of a sash pin  70  (illustrated in  FIG. 1 ). It is also possible, and is preferred in some situations, for locking cam  20  to have a through recess or channel  25  that allows a sash pin to extend more than half way into locking cam  20  (shown in  FIG. 7 ). A through channel  25  in cam  20  allows a sash pin to penetrate deeply into cam  20  and is preferred to increase the wind resistance of a sash. 
         [0020]    Each body part  11   a  and  b  preferably has a recess  72  formed above the end regions of cam  20 . When a sash supported by cassettes  10  is tilted out of the window plane, cam  20  turns to a locking position that aligns its channel  25  or slots  22  with recesses  72 . This allows the heads  73  of sash pin  70  to be raised upward from cam slots  22  or channel  25  and into recesses  72  to facilitate removing a tilted sash from a window. 
         [0021]    Recesses  72  also facilitate replacing a removed sash, because recesses  72  allow extra room above cam  20  to receive sash pin  70  that can then be dropped down into cam slots  22  or  25 . Recesses  72  also provide a somewhat larger area for maneuvering sash pins  70  into shoe bodies  11   a  and  b  before dropping downward into cam channels  25  or slots  22 . The sash pins  70  can have heads  73  that interlock with cam edges  23  to prevent withdrawal of sash pin  70  from shoe cassettes  10  if a window is carried in a suitcase fashion before installation. Sash pins  70  can also be un-headed and long enough to extend deeply into cam  20  for improved wind resistance of a sash. The described arrangement of cam channels  22  and  25 , recesses  72 , and sash pins  70  also allows shoes  11  to be unhanded, so that any shoe can be installed on either side of a sash to be counterbalanced. 
         [0022]    Mounting brackets  50 , to the contrary, are preferably handed so that each bracket is arranged to be mounted on only one side of a sash. This preference is to assure that mounting brackets  50  do not interfere with tilt latches of a counter balanced sash.  FIG. 4  illustrates one way that this can be accomplished. Tilt latch  75 , which is typically spring loaded to be snapped into latching engagement with channel slot  62  when a tilted sash is moved back to an upright position, runs in slot  62  of channel  60  where it moves up and down with sash  50  to prevent accidental tilting. When latches  75  are moved inward against their spring bias, they allow deliberate tilting of a counter balanced sash. 
         [0023]    Brace  55  of mounting bracket  50  is preferably mounted in an orientation that clears tilt latch  75  so that mounting bracket  50  does not interfere with vertical movement of tilt latch  75  past mount  50 . The left- and right-handedness of mounting bracket  50  as identified by the A and B markings appearing on brackets  50  in  FIGS. 1 and 2  ensures that a mounting bracket on each side of a window sash clears the tilt latch  75 . 
         [0024]    Lower corners of body parts  11   a  and  b  preferably have molded recesses  82  that can receive locking pads  80  or  81  to increase a frictional locking effect when a balanced sash tilts to pivot cam  20  to a locking position. Locking pads  80  and  81  (schematically shown in  FIG. 2 ) are alternatives that can be pressed into a recess  82  to achieve a pressed fit in recess  82  for locking pad  80  or a snap fit in recess  82  for locking pad  81 . Pads  80  and  81  can be surfaced with different materials and given different surface configurations to increase the frictional security of a shoe lock achieved by pivoting of cam  20  to spread shoe bodies  11   a  and  b  somewhat apart within channel  60 . 
         [0025]    When locking cam  20  pivots with a tilted sash, its cam surface  21  slides in between lower edges of shoe bodies  11   a  and  b  to splay the shoe bodies apart and lock the shoe cassette in place in a jamb channel. This splaying apart of the lower regions of shoe bodies  11   a  and  b  also produces a force that tends to rotate the shoe bodies relative to each other as they are forced apart by cam surface  21 . Such rotation would tend to diminish the splaying apart of the shoe body halves, and this tendency is overcome by projections  15  and corresponding recesses  16  that are formed in the lower region of each shoe half. As bodies  11   a  and  b  splay apart in response to rotation of cam surface  21 , projections  15  remain engaged with recesses  16  to prevent any relative rotation between shoe halves  11   a  and  11   b.  Recesses  16  can be formed as inward facing parts of recesses  82  whose outward facing parts can receive locking pads  80  or  81 . Projections  15  and recesses  16  are also preferably alternately formed on each body half  11   a  and  b  so that these halves remain identical to each other while providing a pair of mating recesses  16  and projections  15 .