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REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims an invention which was disclosed in Provisional Application No. 60/560,061, filed Apr. 7, 2004, entitled “Slotted Extruded Inverted Carrier with Improved Pin Ingress and Egress”. 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  
       [0002]     The invention pertains to the field of tilt lock carriers. More particularly, the invention pertains to a tilt lock carrier for use with various types of counterbalances that has interchangeable locks to adapt the carrier to window systems with different size jamb pocket dimensions, and has features to reduce the difficulty normally associated with the installation and removal of a sash.  
       BACKGROUND OF THE INVENTION  
       [0003]     Many window sash counterbalance systems utilize a locking carrier to prevent the counterbalance from retracting when the sash is tilted out for cleaning, and when the sash is removed for maintenance or other reason. Typically, such locking carriers comprise a carrier body, cam and lock wherein the carrier body is attached to the counterbalance, the carrier body rotatably supports the cam, and slidably supports the lock in proximity to the cam. A pivot bar, attached at a bottom corner of a sash, and protruding laterally, is received in a slot or opening in the cam, such that tilting of the sash rotates the cam, which in turn slides or slidably expands the lock to a position wherein the lock bears outwardly against one or more surfaces forming the interior of the jamb pocket. Friction forces generated by the outwardly bearing lock are sufficient to prevent the counterbalance from moving the locking carrier, even if the weight of the sash is removed. In some embodiments, the outward portions of the lock element may be metallic and designed to imbed slightly into the surface of the jamb pocket wall to prevent carrier motion. Such carriers are commonly manufactured in multiple sizes to properly fit the many different jam pocket configurations prevalent in the window industry. Examples of such tilt lock carriers can be found in U.S. Pat. No. 6,032,417, issued to Jakus et al.; and in U.S. Pat. No. 4,610,108, issued to Marshick.  
         [0004]     In many window systems, the jamb element adjacent the sash is formed from a plastic material, commonly extruded, and contains one or more pockets of an approximately rectangular cross section, which extend along the normal direction of travel of the window sash. Typically, a counterbalance and carrier are mounted within the pocket, with the pocket forming a guideway for the carrier as it travels. A slot shaped opening, in the side of the jamb pocket adjacent the sash, allows the protruding end of the pivot bar to penetrate the pocket, and engage the cam within the carrier.  
         [0005]     When the counterbalance, or its attachment means to the carrier are such as to not obstruct the slot shaped opening of the jamb pocket immediately above the carrier, the carrier and cam can be designed to allow the pivot bar to drop vertically into the cam slot, thus enabling the sash to be easily installed and removed. (This style of carrier is illustrated in U.S. Pat. No. 5,301,467, issued to Schmidt et al., and in the carriers of  FIGS. 6, 7 , and  17  of U.S. Pat. No. 6,032,417). A further advantage of drop in designs is that they allow the use of pivot bars with interference features such as interference members or shapes (typically “T” or “L” shaped ends), that interfere with an element of the carrier to prevent axial withdrawal of the pin from the carrier. Thus, in the examples given, the overhanging portions of the “T” or “L” can engage at least one feature of the carrier, including its cam or lock, to “tie in” the pivot bar so that it does not slide axially out of engagement with the carrier, when, for instance an uninstalled window unit is lifted and carried by the center of one of its jambs.  
         [0006]     To install a sash in this type of counterbalance system, the sash is first rotated slightly about a horizontal axis perpendicular to the plane of the window, such that the horizontal distance between the ends of the protruding pivot bars is less than the distance between the opposed faces of the jamb elements. The sash is then inserted into the opening between the jamb faces, and rotated back towards a horizontal position, such that the pivot bars now protrude into the slot shaped openings. The sash is then further rotated to the horizontal orientation and lowered, while in the horizontal orientation, so as to insert the pivot bars into their respective cam slots. Finally, the sash is tilted to its normally upright position, rotating the cams to positions where the lock elements are allowed to contract away from their extended, locked positions, freeing the carriers and counterbalances to support and guide the sash.  
         [0007]     When the counterbalance, or its attachment means to the carrier obstruct the slot shaped opening, convenient drop in sash installation can still be provided, if the carrier and cam are extended toward the sash through the slot shaped opening in the jamb a distance sufficient to allow the extended portions of the carrier and cam to support the end of the pivot bar, while still allowing the pivot bar to drop past the counterbalance structure. While this carrier design does facilitate easy sash installation and removal, it requires a reduction in the size of the sash that could be fitted within a given window frame opening.  
         [0008]     However, when the counterbalance system was such as to obstruct the slot shaped opening of the jamb pocket immediately above the carrier, and it was undesirable to reduce sash width to allow for a drop in carrier design, the window manufacturer and users of the window have been required to engage in an extremely difficult sash installation procedure comprising the following steps: 1) position the two counterbalances at different vertical positions, and operate the cams to lock the carriers in such positions, 2) rotate the sash slightly about a horizontal axis perpendicular the plane of the window, 3) insert the sash into the opening between the jambs, 4) insert one of the pivot bars into the opening of its respective cam, 5) overcome the locking force of the engaged carrier, and force that carrier upward or downward, until the unengaged pivot bar can be aligned with the opening of its respective cam, 6) force the first carrier to a position horizontally opposite the second, while guiding the second pivot bar into its respective cam opening, and 7) rotate the sash to its normally upright position, to unlock the carriers for normal sash operation. Illustrations of this type of carrier can be seen in U.S. Pat. No. 5,802,767, issued to Slocomb et al., and in the above referenced U.S. Pat. No. 4,610,108.  
       SUMMARY OF THE INVENTION  
       [0009]     An improved carrier has been developed for use with counterbalances wherein the counterbalance, or its means of attachment to the carrier, obstruct the slot shaped opening of the jamb pocket of the window in which the counterbalances are installed. This improved carrier allows for drop in type sash installation without having extended features which would preclude the use of wider sash and without having to position the two counterbalances at different vertical positions in order to insert a window sash&#39;s pivot bars into the carriers&#39; cam slots.  
         [0010]     A further advantage of this carrier is that it is adapted to receive multiple lock elements, wherein the lock elements can be sized to configure the carrier for use in different sized jamb pockets, eliminating the need for manufacturing tooling to produce the carrier component in a variety of sizes.  
         [0011]     A still further advantage of this carrier is that it has features to retain the cam in its assembled position, independent of the lock, allowing the carrier and cam to be applied to a counterbalance prior to assigning the counterbalance to a particular jamb pocket size. When the particular application for the counterbalance is determined, the appropriate lock element can be readily applied, to properly size the counterbalance system to the application. This flexibility allows economy of inventory in situations where a window manufacturer may make a number of different model windows, perhaps featuring different jamb pocket sizes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  shows a front perspective view of an improved carrier assembly produced in accordance with this invention, in an unlocked state, attached to a conventional inverted block and tackle counterbalance.  
         [0013]      FIG. 2  is an enlarged front perspective view of the carrier assembly of  FIG. 1 , in a locked state.  
         [0014]      FIG. 3  is an enlarged front perspective view of the improved carrier assembly, in an unlocked state, attached to a conventional inverted block and tackle counterbalance, with an alternate lock element, to adapt the carrier to a larger jamb pocket.  
         [0015]      FIG. 4  is an enlarged front perspective view of the carrier assembly of  FIG. 3 , in a locked state.  
         [0016]      FIG. 5  is a front perspective view of the improved carrier.  
         [0017]      FIG. 6  is a rear perspective view of the improved carrier.  
         [0018]      FIG. 7  is a front perspective view of the cam employed in the improved carrier assemblies of  FIGS. 1-4 .  
         [0019]      FIG. 8  is a rear perspective view of the cam of  FIG. 7 .  
         [0020]      FIG. 9  is a front perspective view of an improved carrier, with cam installed.  
         [0021]      FIG. 10  is a cross-sectional view of the improved carrier and cam of  FIG. 9  showing the cam retention snap.  
         [0022]      FIG. 11  is a front perspective view of the lock element used in the improved carrier assemblies of  FIGS. 1-2 .  
         [0023]      FIG. 12  is a front perspective view of the alternate lock element used in the improved carrier assemblies of  FIGS. 3-4 .  
         [0024]      FIG. 13  is a perspective view of the improved carrier assembly of  FIG. 4 , installed in a jamb pocket, with a typical pivot bar in a position to be received in the carrier and cam.  
         [0025]      FIG. 14  depicts the improved carrier assembly of  FIG. 13 , when the pivot bar has been received into the carrier and cam.  
         [0026]      FIG. 15  shows the improved carrier assembly of  FIG. 14 , wherein the pivot bar has been rotated to a position consistent with the sash (not shown) having been tilted to it normal operating vertical orientation.  
         [0027]      FIG. 16  is a top view of the improved carrier assembly of  FIG. 4 , illustrating the protrusion of the pivot bar beyond the outer face of the counterbalance structure, and illustrating the extension of the carrier face within the thickness of the return legs of the jamb extrusion.  
         [0028]      FIG. 17  is a front perspective view of the improved carrier assembly of  FIG. 2 , showing the access slot top.  
         [0029]      FIG. 18  is a cross-sectional view of the carrier assembly of  FIG. 17 , illustrating the arcuate path traveled by the end of the pivot bar during sash installation or removal. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]     In  FIGS. 1-4 , a carrier assembly  100  is affixed to a counterbalance, represented in these illustrations as a block and tackle counterbalance  10 , similar to that disclosed in U.S. Pat. No. 6,041,476, issued to deNormand, and more particularly, a block and tackle counterbalance  10 , utilized in an inverted orientation, wherein the carrier assembly  100  is affixed to channel  12  of block and tackle counterbalance  10 . Carrier assembly  100  may be affixed by any one of several methods, including riveting, screwing, or engagement of suitable interlocking features. Carrier assembly  100  comprises a carrier body  200 , a cam  300 , and a lock element  400 ,  500 .  
         [0031]     Referring to  FIGS. 5-10 , carrier body  200  has a cam pocket  202  defined by cam pocket wall  204  and cam pocket end  206 , which receives the cylindrical front portion  302  of cam  300 , with cylindrical surfaces  304  fitting concentrically within cam pocket wall  204 , and front faces  306  abutting cam pocket end  206 . Carrier body  200  has a cam snap  208  disposed alongside cam pocket  202 , with at least cam snap tip  210  encroaching within cam pocket  202 . When cam  300  is inserted into cam pocket  202  of carrier body  200 , cam snap  206  resiliently deforms to allow the insertion of cam  300 , returning to its undeformed state, when cam  300  is fully inserted, positioning cam snap tip  210  behind annular ledge  310  of cam  300 , preventing cam  300  from being dislodged from cam pocket  202 , while yet allowing cam  300  to rotate within the confines of cam pocket  202 .  
         [0032]     Carrier body  200  also has a transverse slot  212  to receive one of a lock element  400 , 500  shown in  FIGS. 11,12 . Lock elements  400 ,  500  are comprised each of two ear portions  402 ,  502 , having opposed follower surfaces  406 ,  506 , and interconnected by a serpentine spring section  404 ,  504 . Ear portions  402 ,  502  of a lock element  400 , 500  are inserted into transverse slot  212  of carrier body  200 , with lock snaps  412 , 512 , extending through and engaging snap slots  214  of carrier body  200 , and with ear portions  402 ,  502  sitting astride cam portion  312  of cam  300 , and follower surfaces  406 ,  506  of the lock element  400 , 500  abutting cam surfaces  314  of cam  300 . Ear portions  402 ,  502  and lock snaps  412 ,  512  are sized to fit respectively within transverse slot  212  and snap slots  214  with sufficient clearance to permit ear portions  402 ,  502 , and lock snaps  412 ,  512  to slide laterally outward, as illustrated in  FIGS. 2,4 , when urged to do so by rotation of cam  300  *from a first position in which abutting cam surfaces  314  are spaced at a first distance to a second position wherein the abutting cam surfaces  314  are spaced at a second distance greater than the first distance? 
         [0033]     In  FIGS. 13-16 , a carrier assembly  100  affixed to a block and tackle counterbalance  10  is shown installed in a portion of a jamb extrusion  700  typical of those used in the construction of a double hung window. A jamb pocket  702  is bounded by back wall  704 , side walls  706 , and front walls  708 , and extends the length of jamb extrusion  700 . A pivot bar  600  attached to the lower corner of a double hung window sash (not shown for clarity) is received through slot  712  formed between the ends of return legs  710  of jamb extrusion  700 , and within wider portion  218  of access slot  216  of carrier body  200 , as illustrated in  FIG. 13 . In  FIGS. 13, 14  cam  300  has been rotated to its second position, wherein cam slot  308  is aligned with narrower portion  220  of access slot  216 . As pivot bar  600  (with attached sash, in a proper orientation for installation) is lowered, narrower portion  220  of access slot  216  guides the head  602  of pivot bar  600  into alignment with cam slot  308  of cam  300 , allowing head  602  to easily and smoothly enter cam slot  308 , achieving the position depicted in  FIG. 14 . In  FIG. 15 , pivot bar  600  has been rotated to a position corresponding to the tilted in, operating position of the sash, and cam  300 , as a result of engagement with head  602  of pivot bar  600  within cam slot  308 , has been rotated by pivot bar  600  to its first rotational position.  
         [0034]     Pivot bar hole  224  in face  222  of carrier body  200  is sized to allow the rotation of pivot bar  600 , while preventing wings  604  from moving axially through pivot bar hole  224 , to provide the desired “tie in” behavior.  
         [0035]     When cam  300  is rotated from its first position to its second position, sliding ear portions  402 ,  502  of lock elements  400 ,  500  laterally outward, brake surfaces  408 , 508  are forced against side walls  706  of jamb pocket  702 , producing the necessary frictional forces to hold carrier assembly  100  and counterbalance  10  in position, when the sash is tilted out for cleaning, or removed for servicing. When the cam is rotated from its second position to its first position, serpentine springs  404 ,  504 , retract the extended ear portions  402 ,  502 , withdrawing brake surfaces  408 ,  508  from contacting side walls  706  of jamb pocket  702 , freeing carrier assembly  100  and counterbalance  10  to move vertically within jamb pocket  702 , to provide the desired guidance and support for the sash.  
         [0036]     In the prior art, and in commercial practice there are many examples of carriers with lock elements wherein the lock element is manufactured in several configurations with slight differences in dimension to compensate for minor differences in jamb pocket dimensions which may occur between manufacturers, or where a different locking friction is desired. For major differences in jamb pocket dimensions, carrier manufacturers have provided carrier assemblies sized for the particular jamb pocket configuration, wherein the carrier bodies have also been sized to the jamb pocket size. Also in the prior art, and in commercial practice, carrier assemblies comprising a carrier body, a cam, and a lock element have been designed such that the cam is positively retained in the assembly by the presence of the lock element.  
         [0037]     Carrier assembly  100  represents an improvement over prior art, in that it utilizes a single carrier body  200 , and cam  300  in all applications. Only the lock element  400 ,  500  is specific to the particular jamb pocket size, thus, adapting carrier assembly  100  to a new and different jamb configuration can be accomplished by creating only a new lock element, similar to lock element  500 , wherein lock extensions  510  are appropriately sized to fit the desired new jamb pocket dimensions. Further, when a particular window manufacturer may be making more than one model of window, perhaps with jamb extrusions having different sized jamb pockets, carrier bodies  200 , with cams  300  installed can be affixed to appropriate counterbalances, and placed into inventory. Lock elements  400  and  500  can also be placed into inventory. As a window is constructed, a pair of counterbalances of the correct weight capacity for each sash can be withdrawn from inventory, along with a pair of the appropriate lock elements  400 , 500 , dependent on the jamb pocket size present in the window under construction. The selected lock elements  400  or  500  can then be snapped in position, to complete the carrier assemblies  100 , and the completed carrier assemblies  100  and counterbalances  10  can be installed in the jamb pockets of the window under construction. This inventory scheme will generally allow a smaller overall inventory than would be required if separate inventories of completed carrier and counterbalance assemblies were maintained with multiple sizes of carriers.  
         [0038]     Carrier body  200  thus represents an improvement over prior art, in that it retains an installed cam  300  independently of the presence of a lock element  400 , 500 , which enables a later assembly of lock element  400 ,  500 .  
         [0039]     A seven step installation procedure for installing sash into a window equipped with a current art inverted block and tackle counterbalances with attached carriers was described above. A simplified method for the installation of a window sash into a window constructed with jamb extrusions  700 , and equipped with improved carrier assemblies  100  will now be described, with reference to  FIGS. 16-18 , and features of carrier body  200 , which enable this simplified method will be disclosed.  
         [0040]     First and second carrier assemblies  100 , affixed to first and second block and tackle counterbalances  10 , are installed in opposing first and second jamb extrusions  700 , positioned at an approximately equal elevation, and cams  300  are rotated to their respective second positions, with cam slots  308  aligned with access slots  216  of carrier bodies  200 . A sash, with first and second pivot bars  600  affixed to the lower edge of the sash, and protruding beyond the sides of the sash, is rotated about a horizontal axis perpendicular to the plane of the window, such that the horizontal distance between the ends of the pivot bars is less than the horizontal distance between sash faces  714  of the opposing first and second jamb extrusions  700 . The sash with protruding pivot bars  600  is then moved into the intervening space between sash faces  714  of opposing jamb extrusions  700 . The sash is then moved laterally, toward the first carrier assembly  100 , until the head  602  of first pivot bar  600  extends through slot  712  of the first jamb extrusion  700 , and enters into access slot  216  of carrier body  200  of the first carrier assembly  100 . The sash is then lowered, until the head  602  of the first pivot bar  600  is received into cam slot  308  of cam  300  of the first carrier assembly  100 . Next, the sash is rotated about the head  602  of the first pivot bar  600 , toward a horizontal position, causing head  602  of the second pivot bar  600  to move along the arcuate path “A” shown in  FIG. 18 . When head  602  of second pivot bar  600  has been received into cam slot  308  of cam  300  of the second carrier assembly  100 , the sash is finally tilted to its closed normally operating position, causing rotation of pivot bars  600 , and the attendant rotation of cams  300  to their respective first positions, wherein first and second carrier assemblies  100  are unlocked and free to move with and support the installed sash.  
         [0041]     This procedure is advantaged over the more difficult seven step procedure in that there is one fewer steps, and the individual installing a sash is not required physically overpower the carrier locking system to move either balance as described in steps  5  and  6  above. Removal of the sash is accomplished by reversing the installation procedure.  
         [0042]     Pivot bar hole  224  in face  222  of carrier body  200  is sized to allow the rotation of pivot bar  600 , while preventing wings  604  from moving axially through pivot bar hole  224 , to provide the desired “tie in” behavior.  
         [0043]     The radius R of arcuate path “A” is indicative of the widest sash which can be installed in this manner, and is defined by the horizontal distance P that head  602  of second pivot bar  600  extends under an overhanging obstruction, commonly the bottom end  14  of channel  12  of block and tackle counterbalance  10 , and is further defined by the vertical distance D from the centerline of cam  300  of the second carrier assembly  100  to the overhanging obstruction.  
         [0044]     As can be appreciated by inspection of  FIG. 18 , the radius R of arcuate path “A”, which is indicative of the widest sash that can be installed with the above described method, can be maximized by decreasing the overhang distance P, while increasing the vertical distance D.  
         [0045]     To decrease the overhang distance P, one could employ a counterbalance of lesser size, however this option is generally unacceptable, as counterbalances of lesser size typically have reduced weight carrying capacities. Current art and commercially available carriers either fit within the confines of a jamb pocket, or provide for drop in capability by extending substantially through slot  712  of jamb extrusion  700 , with attendant loss of sash width capacity. A suitable and significant reduction in overhang distance P is realized with carrier body  200  of carrier assembly  100 , by extending face  222  a distance O beyond front wall  708  of jamb extrusion  700 , but not beyond sash face  714  so as to not to force a reduction of sash width.  
         [0046]     Dimension D, at first appearance could be made as large as needed to achieve any desired radius R for path “A”, however at least two factors limit the expansion of dimension D. A first factor is that in a practical window, the overall length of carrier assembly  100  and counterbalance  10  cannot exceed the height of the sash for which it is used, if the upward travel range of the sash is not to be restricted by the counterbalance system. Secondly, the length of the counterbalance  10  is indicative of the maximum distance it can be extended while still providing an appropriate counterbalancing force. With current commercially available double hung windows, a maximum practical travel distance for any sash is 1.5 inches less than the overall height of the sash. With current commercially available block and tackle counterbalances, the maximum practical travel distance is approximately 2 inches greater than the length of the counterbalance. Combining these two factors mathematically, the overall length of carrier assembly  100  extending beyond channel end  14  of block and tackle counterbalance  10  cannot exceed 3.5 inches, somewhat less, if space is needed at the upper end of counterbalance  10 , to effect its mounting within jamb pocket  702 .  
         [0047]     The carrier body  200  depicted in  FIGS. 1-18  has been sized to extend approximately 2.5 inches beyond channel  12 , to which it is affixed, and 0.060 inches beyond front wall  708  of jamb extrusion  700 , and as a result, enables the loading of sash up to approximately 25 inches in width, by the above simplified installation procedure. In the above simplified installation procedure, if the first carrier assembly  100  is positioned at an elevation up to approximately 1 inch lower than the second carrier assembly  100 , sash significantly wider than 25 inches can still be loaded. When tilting a sash installed to carrier assemblies positioned at unequal elevations, the sash will not properly align with sash faces  714  of jamb extrusion  700 , however, at some point before the sash is tilted to its full vertical position, the carrier assemblies  100  will unlock, and allow the sash to be easily aligned to sash faces  714 .  
         [0048]     While the inventions has been described with reference to certain features and structure, various modifications may be made without departing from the principle and scope of this invention. 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.  
       PARTS LIST  
       [0000]    
       
         
           
               10  Block and tackle counterbalance  
               12  Channel  
               14  Channel end  
               100  Carrier assembly  
               200  Carrier body  
               202  Cam pocket  
               204  Cam pocket wall  
               206  Cam pocket end  
               208  Cam snap  
               210  Cam snap tip  
               212  Transverse slot  
               214  Snap slot  
               216  Access slot  
               218  Wider portion  
               220  Narrower portion  
               222  Face  
               224  Pivot bar hole  
               226  Access slot top  
               300  Cam  
               302  Cylindrical front portion  
               304  Cylindrical surface  
               306  Front face  
               308  Cam slot  
               310  Annular ledge  
               312  Cam portion  
               314  Cam surface  
               316  Back face  
               400 ,  500  Lock element  
               402 ,  502  Ear portion  
               404 ,  504  Serpentine spring  
               406 ,  506  Follower surface  
               408 ,  508  Brake surface  
               510  Lock extension  
               412 ,  512  Lock snaps  
               600  Pivot bar  
               602  Head  
               604  Wing  
               700  Jamb extrusion  
               702  Jamb pocket  
               704  Back wall  
               706  Side wall  
               708  Front wall  
               710  Return leg  
               712  Slot  
               714  Sash face

Summary:
This improved carrier allows for drop in type sash installation without having extended features which would preclude the use of wider sash and without having to position the two counterbalances at different vertical positions in order to insert a window sash&#39;s pivot bars into the carriers&#39; cam slots. It is also adapted to receive multiple lock elements, wherein the lock elements can be sized to configure the carrier for use in different sized jamb pockets, eliminating the need for manufacturing tooling to produce the carrier component in a variety of sizes. In addition, it has features to retain the cam in its assembled position, independent of the lock, allowing the carrier and cam to be applied to a counterbalance prior to assigning the counterbalance to a particular jamb pocket size. When the particular application for the counterbalance is determined, the appropriate lock element can be readily applied, to properly size the counterbalance system to the application. Finally, this carrier includes retaining features allowing its use in conjunction with a pin having complementary features such that the pin cannot be pulled axially out of engagement with the cam once it is properly positioned therein.