Abstract:
Disclosed are apparatus for a block and tackle window balance to be incorporated in single and double hung window assemblies. In one embodiment the block and tackle window balance includes a roller secured within a bottom guide to increase range of travel of a window sash.

Description:
TECHNICAL FIELD 
     This invention relates to block and tackle window balance devices for single and double hung windows and, more particularly, to a block and tackle window balance device that provides an increased range of travel within a window frame. 
     BACKGROUND INFORMATION 
     Hung window assemblies generally include a window frame, a lower window sash, an upper window sash, a pair of window jambs, two sets of jamb pockets, and at least one window balance device for offsetting the weight of a window sash throughout a range of travel within the window frame. Block and tackle window balance devices use a combination of a spring and pulleys located within a channel to balance the weight of the window sash at any position within the jamb pockets. 
     In some block and tackle window balance devices, the channel containing both the spring and pulleys is attached to the window sash, and a cord, which connects the pulleys together, is attached to a jamb mounting hook that is connected to a side jamb. A disadvantage of this type of device is that the travel distance of the window sash is limited by some of the pulleys located within the rigid channel interfering with the jamb mounting hook that attaches the window balance to the window jamb. 
     SUMMARY OF THE INVENTION 
     In general, in one aspect, the invention relates to a block and tackle window balance device for use with single and double hung windows that affords increased window opening travel distance. In one embodiment, the block and tackle window balance device includes a channel, a spring with a first end and a second end, a translatable pulley block unit, a fixed pulley block unit, a cord, a top guide, and a bottom guide with a bottom guide roller. The top and bottom guides are connected to opposite ends of the channel. The spring, the translatable pulley block unit, and the fixed pulley block unit are all located within the channel. The first end of the spring and the fixed pulley block unit are fixed at opposite ends of the channel. The second end of the spring is connected to the translatable pulley block unit. The translatable and fixed pulley block units are connected by the cord. The cord is threaded around both the translatable and fixed pulley block units and extends around the bottom guide roller located within the bottom guide. 
     In another embodiment, the block and tackle window balance device includes a top guide including a top angled portion and a bottom portion. The bottom portion of the top guide is connected to one end of the channel. In still another embodiment, the top angled portion of the top guide is sized to receive a member from a window sash. 
     In yet another embodiment, the block and tackle window device includes a bottom guide that extends beyond the rigid channel. In still yet another embodiment, the bottom guide of the device further includes a channel to receive a portion of a window sash. 
     In general, in one aspect, the invention relates to a method of providing increased travel of a window sash slidably mounted in a window frame. The method includes three steps. A first step is to provide a window assembly that includes a window frame with jambs with jamb pockets, an upper window sash, a lower window sash, and at least one block and tackle window balance device having a channel and a bottom roller for dispensing a cord. The channel has a first end and a second end. The bottom roller is mounted proximate to the second end of the channel with a first distance between the first end of the channel and the bottom roller. A second step is to remove the block and tackle window balance device from the window assembly. A final step is to provide and to install an increased travel window balance device. The increased window balance device has a channel with a first end and a second end and a bottom guide roller for dispensing a cord. The bottom guide roller is mounted proximate to the second end of the channel and a second distance is defined as the length between the first end of the channel and the bottom guide roller. The second distance of the increased window balance device is greater than the first distance of the removed block and tackle window balance device. 
     The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. 
     FIG. 1 is a perspective view of a double hung window. 
     FIG. 2A is a perspective view of a prior art block and tackle window balance. 
     FIG. 2B is another perspective view of the prior art block and tackle window balance of FIG. 2A with one of two side walls of the U-shaped channel removed. 
     FIG. 3 is a perspective rear view of the prior art block and tackle window balance. 
     FIG. 4A is a perspective view of an embodiment of a block and tackle window balance of the invention. 
     FIG. 4B is perspective view of the block and tackle window balance of FIG. 4A with one of two side walls of the U-shaped channel removed. 
     FIG. 5 is a perspective view of an embodiment of a block and tackle window balance of the invention mounted within a window jamb. 
     FIG. 6 is an enlarged front view of a top guide of the block and tackle window balance of FIG. 4A attached to a cam. 
     FIG. 7A is a front view showing a closed position of a window assembly with prior art block and tackle window balances. 
     FIG. 7B is a front view showing an open position of the window assembly with prior art block and tackle window balances. 
     FIG. 8A is a front view showing a closed position of a window assembly with an embodiment of a block and tackle window balances of the invention. 
     FIG. 8B is a front view showing an open position of a window assembly with block and tackle window balances of the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, shown is a double hung window assembly  100  in which a block and tackle window balance constructed in accordance with the teachings of the present invention can be used. The double hung window assembly  100  includes a window frame  102 , a lower window sash  104 , an upper window sash  106 , and a pair of window jambs  107 . Within each window jamb  107 , jamb pockets  108  are defined. The lower window sash  104  and upper window sash  106  slide vertically within the jamb pockets  108 . Generally, window balances are attached to the lower and upper window sashes  104 ,  106  to balance the weight of the window sashes at any vertical position within the jamb pockets  108 . 
     FIGS. 2A,  2 B, and  3  show perspective views of a prior art block and tackle window balance  200 . FIG. 2A shows the prior art block and tackle window balance  200  in full, whereas FIG. 2B shows the prior art block and tackle window balance  200  with one side wall of a rigid U-shaped channel  205  cut away so that components within the window balance  200  are more visible. FIG. 3 shows a rear view of the window balance  200 . 
     The block and tackle window balance  200  includes a spring  220 , a translatable pulley unit  230 , a fixed pulley unit  235 , a roller  239 , and a cord  240  all housed with the rigid U-shaped channel  205 . Attached to the two ends of the rigid U-shaped channel  205  with fasteners  212 ,  216  are a top guide  210  and a bottom guide  215  that are used to connect the window balance  200  to either the upper or lower window sashes  104 ,  106  and to help guide the vertical motion of the window balance  200  within the jamb pockets  108 . The top guide  210  includes an upper portion  202  and a lower portion  203 . The upper portion  202  of the top guide  210  is angled and is sized to be received by a member attached to a window sash, such as a cam. The bottom guide  215  includes a back portion  213 , best seen in FIG. 3, that encases a portion of the rigid channel  205 . Within the back portion  213  of the bottom guide  215  is a channel  214  sized to receive a portion of a window sash. 
     The rigid U-shaped channel  205  has a back wall  206  and two side walls  207 ,  208  that in combination form the U-shape. The rigid U-shaped channel  205  serves as an external frame to which the components of the window balance  200  can be secured. The rigid U-shaped channel  205  also keeps components located within the rigid U-shaped channel  205  free of debris and particulate matter. The spring  220 , the translatable pulley unit  230 , the fixed pulley unit  235 , and the roller  239  are located inside the rigid U-shaped channel  205 . Both of the translatable pulley unit  230  and the fixed pulley unit  235  include one or more pulleys rotatable around respective axles. 
     Components within the rigid U-shaped channel  205  work in combination to create a force to counterbalance the weight of the attached sash at any vertical position within the window frame  102 . These components are attached to each other such that a first end  219  of the spring  220  is connected to the translatable pulley unit  230 , and the translatable pulley unit  230  is connected to the fixed pulley unit  235  and the roller  239  via the cord  240 . A pulley in the fixed pulley unit  235  and the roller  239  may be contained in a frame  236 . To secure the components within the rigid U-shaped channel  205 , the second end  221  of the spring  220  and the frame  236  are fixed to opposite ends of the rigid U-shaped channel  205  via respective fasteners  218 ,  243 . The frame  236  is also used to secure a pulley axle  237  and a roller axle  238 , around which the pulley in the fixed pulley unit  235  and the roller  239  respectively rotate. A first distance “AA”  275  is defined by a length extending between the upper portion  202  of the top guide  210  and the roller axle  238 . The spring  220  and the translatable pulley unit  230  are connected together by hooking the first end  219  of the spring  220  through an upper slot opening  229  in a frame  225 . The frame  225  houses the translatable pulley unit  230  and a pulley axle  232  around which a pulley in the translatable pulley unit  230  rotates. The cord  240 , which can be a rope, string, or cable, has a first end  241  and a second end  242 . The first end  241  of the cord  240  is secured to the frame  225  and the second end  242 , which is a free cord end, is threaded through the translatable pulley unit  230 , the fixed pulley unit  235 , and the roller  239 , thereby connecting all three components together. After the cord  240  connects the three components together, a jamb mounting attachment  245  is secured to the second end  242  of the cord  240 . When the prior art window balance  200  is located in the jamb pocket  108 , the jamb mounting attachment  245  engages an opening  430  (FIG. 5) within one of the jamb pockets  108 , securing the window balance  200  to the window jamb  107 . 
     The spring  220  provides the force required to balance the sashes. The spring  220  is extended when the second end  242  of the cord  240  with the jamb mounting attachment  245  is pulled, causing the frame  225  to move within the rigid U-shaped channel  205  towards the frame  236 , which is fixed. As the frame  225  moves towards the frame  236 , the spring  220  is extended. 
     FIGS. 4A and 4B show an embodiment of a block and tackle window balance  300  in accordance with the teachings of the present invention. The window balances  300  act to counterbalance the weight of the window sashes  104 ,  106  at any vertical position within the window frame  102 . FIG. 4A show one perspective view of the window balance  300  and FIG. 4B shows another perspective view of the same balance, but with a side wall of the rigid U-shaped channel  305  removed. The window balance  300  includes the rigid U-shaped channel  305 , a top guide  310 , a bottom guide  315 , a spring  320 , a translatable pulley unit  330 , a fixed pulley unit  335 , a bottom guide roller  350 , and a cord  340 . The top guide  310  and the bottom guide  315  are fixed to the rigid U-shaped channel  305  by fasteners  312 ,  316 . The top guide  310  is used to help connect the block and tackle window balance  300  to the window sash  104 ,  106  and to help guide the movement of the block and tackle window balance  300  within the jamb pocket  108 . The top guide  310  may include a top angled portion  302  and a bottom portion  303  as shown in FIGS. 4A and 4B. The bottom guide  315  is also used for connection and guidance purposes, but the bottom guide  315  further serves as a frame for housing the bottom guide roller  350 . The bottom guide  315  extends beyond the rigid U-shaped channel  305  and, therefore, the bottom guide roller  350  is located outside of the rigid U-shaped channel  305 . A back portion  313  of the bottom guide  315  may include a channel  314  for receiving a portion of the window sash, as depicted in FIG.  5 . Some windows have a groove running along a bottom rail of the sash. On conventional balances, the bottom guide can drop into this groove so a manufacturer needs to use a shorter balance to avoid dropping into the groove. This effectively reduces the amount of travel, because shorter balances have to be used. The bottom guide  315  of the present invention is configured so the contact point of the bottom guide  315  to the sash is higher on the balance  300  so the groove is avoided and a longer balance with a greater spring force can be used. This can afford increased force for balancing the sash at any vertical position, as well as increased amount of travel resulting from the longer balance. 
     The spring  320 , the translatable pulley unit  330 , and the fixed pulley unit  335  are located within the rigid U-shaped channel  305 . In the embodiment shown in FIGS. 4A and 4B, the translatable pulley unit  330  includes two pulleys  326 ,  327  that are rotatable about a single pulley axle  328 , however, in other embodiments, the translatable pulley unit  330  may contain one or more pulleys rotatable about the pulley axle  328 . Similarly, the fixed pulley unit  335 , as shown in FIGS. 4A and 4B, includes two pulleys  331 ,  332  that rotate about a single pulley axle  333 ; however, in other embodiments, the fixed pulley unit  335  may contain one or more pulleys that rotate about the pulley axle  333 . A first end  319  of the spring  320  is fixed with respect to the rigid U-shaped channel  305  via a fastener  318 . In the disclosed embodiment, the fastener is a rivet; however the fastener could also be a support member welded between the two side walls of the rigid U-shaped channel  305 , a hook secured to or formed in the rigid U-shaped channel  305 , or any other device which secures the first end  319  of the spring  320  to the rigid U-shaped channel  305 . The second end  321  of the spring  320  is attached to a frame  325 , which houses the translatable pulley unit  330 . To connect the spring  320  to the frame  325 , the second end  321  of the spring  320  hooks through an opening  329  in the frame  325 . The cord  340  has a first end  341  and a second end  342 . The first end  341  of the cord  340  is attached to the frame  325  through a frame opening  322 . The second end  342  is attached to a jamb mounting hook  345 . The cord  340  is threaded through the translatable pulley unit  330 , the fixed pulley unit  335 , and around the bottom guide roller  350 , connecting the three components together. The cord  340  in the disclosed embodiment is a string, however it may also be a rope, or a cable. Both the fixed pulley unit  335  and the bottom guide roller  350  are fixed with respect to the rigid U-shaped channel  305 . The fixed pulley unit  335  is housed within a frame  336  and rotates around the pulley axle  333 . The frame  336  is secured within the rigid U-shaped channel  305  with a fastener  337 . In an alternative embodiment, the frame  336  is not required, the fixed pulley unit  335  rotates around an axle supported between side walls of the rigid U-shaped channel  305 . In yet another alternative embodiment, the fixed pulley unit  335  can be integral with the bottom guide  315  and as a result, fasteners  337  and  316  can be eliminated because tension of the spring  320  will keep the bottom guide  315  engaged with or connected to the rigid U-shaped channel  305 . The bottom guide roller  350  is located within the bottom guide  315  and rotates around a bottom guide axle  352 . A second distance “BB”  375  is defined as the length extending between the top angled portion  302  of the top guide  310  and the bottom guide axle  352 . It should be noted that the second distance “BB”  375  is greater than the first distance “AA”  275  of the window balance  200 . 
     To use the block and tackle window balance  300  within the window assembly, the balance is connected to both the window jamb  107  and to either the lower window sash  104  or the upper window sash  106 . Referring to FIG. 5, the block and tackle window balance  300  is attached to the window jamb  107  via the jamb mounting hook  345 . The jamb mounting hook  345  is secured within an opening  430  within the jamb pocket  108 . The window balance  300  is then connected to a window sash by inserting a portion of the window sash into the channel  314  of the bottom guide  315  and connecting a cam  405  mounted on the top of the window sash  400  to the top angled portion  302  of the top guide  310 , as shown in FIG.  6 . 
     The spring  320  of the window balance  300  creates the force required to counterbalance the weight of the window sash. However, because the bottom guide roller  350  is located in the bottom guide  315 , instead of within the rigid U-shaped channel  305  as in prior art balances, window sashes with the block and tackle window balances  300  as disclosed in this application provide greater travel distance. FIG. 7A is an illustration of a window assembly  500  with two prior art window balances  200  attached to a lower window sash  504 . In FIG. 7A, the lower window sash  504  is in a closed position. FIG. 7B shows the window assembly  500 , but with the lower window sash  504  in a fully open position. The standard travel distance of a window sash attached to the prior art window balance  200  is labeled “CC”  520  in FIG.  7 B. The window sash  504 , as shown in FIGS. 7A and 7B, is prevented from achieving a greater travel distance by the roller  239 , located within the rigid U-shaped channel  205 , hitting the jamb mounting hook  245 . 
     FIGS. 8A and 8B show a schematic of the window assembly  600  with block and tackle balances  300  of the present invention. FIG. 8A shows the window assembly  600  in the closed position, while FIG. 8B shows the window assembly  600  in the fully open position. Because the bottom guide roller  350  is mounted within the bottom guide  315  instead of within the rigid U-shaped channel  305 , the window sash  604  can travel a greater distance before the bottom guide roller  350  hits the jamb mounting hook  345 , resulting in a greater travel distance, labeled “DD”  530  in FIG.  8 B. It should be noted that the distance “DD”  530  is greater than the distance “CC”  520 . The greater travel distance is an important feature, because it allows for an increased window clearance that will help persons who are using the window assembly as an emergency 
     Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims.