Abstract:
A new and improved window assembly includes a window frame, and a window sash having an open-tilted and a closed position. The window sash has pivot pins that engage kidney shaped receptacles located on the window frame. The kidney shaped receptacles permit movement of the window sash into the open-tilted or closed position. The design of the present invention minimizes the parts needed to assemble the window assembly making such a window assembly cheaper to manufacture and easier to assemble.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to a window assembly, and more particularly to a cost-effective hopper window assembly that is capable of maintaining an open-tilted position. 
   When a simple window assembly is preferred, it is well known in the art to utilize a hopper window, i.e., a horizontal window comprising a window frame and a single window sash. Such window hoppers may be intended for use at or below grade for the purpose of ventilating a basement or cellar. Alternatively, window hoppers may be located in a basement cellar so that during construction of a building, the cellar window hopper allows construction workers to pass tools into and out of the building. In such situations, hopper windows are an alternative to the traditional double-hung window assemblies. 
   Hopper window assemblies are typically designed to open from the top of the window so as to allow the window to tilt inwards into a building. This allows for greater ease in cleaning the exterior side of the window assemblies. Hopper window assemblies are generally capable of maintaining a plurality of positions. However, to achieve such positions, prior art window assemblies often require the assembly and installation of additional window devices in order to position and maintain the window hopper in various positions. 
   For example, it is known in the art to use a shoe and bracket assembly in order to position the window sash of a window hopper assembly at various angular positions. The shoe is generally comprised of several components, including a spring that provides a biasing force against the bracket. An arm is then used to connect the window sash to the shoe so as to permit the window sash to be tilted and maintained at any angle between the window sash&#39;s open and closed position. 
   These and similar hopper window assemblies that require the installation of additional parts or devices have several drawbacks in terms of cost and time. The increase in parts requires the manufacture of more intricate window sashes, corresponding window frames, and devices capable of manipulating the angular position of the window sashes. The increase in the number of parts naturally lends itself to the need for additional assembly time. The addition of a shoe and bracket assembly to a window hopper assembly will require the assembly of the shoe in the bracket, as well as, the connection of the arm at one end to the shoe bracket and the connection of the arm at its other end to the window sash. Furthermore, there may be additional costs associated with maintaining such hopper window assemblies because replacement parts may be required after devices used in the window assembly have worn down over time. Indeed, the more parts that are needed for the window assembly, the greater the probability that one or more parts will break down. 
   Additionally, the window sashes of prior art window hopper assemblies are difficult to remove due to the window connections between the window sashes and the window frames. Removal of such window sashes requires the need for additional tools and time to remove the window connections. Moreover, if the decision is made not to remove the window connections, such that the window sash is not separated from the window frame, construction workers and the like must very carefully hand tools or items through the window opening without destroying the window connections or the glass window pane. 
   It would therefore be beneficial to provide a window assembly that is sturdy, cheaper to manufacture, and easy to assemble, as well as, one that requires little to no maintenance, and provides greater ease for construction workers and the like to pass materials into and out of a building. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the shortcomings of the prior art by providing a window assembly that is cheaper to manufacture, easy to assemble, less likely to breakdown, and requires little to no maintenance. The present invention requires few parts; namely, a window frame, a window sash and window pane, and pivot pins. In other words, the window assembly according to the present invention does not require the installation of additional parts or devices to maintain the window sash in stationary positions, such as those disclosed in the prior art. Moreover, the ability of the window sash of the present invention to be completely removed from the window frame provides construction workers and the like greater ease in passing tools into and out of the building. Accordingly, various window assemblies in accordance with the present invention are disclosed which reduce the number of parts needed to assemble a hopper window assembly, as well as, reduce the costs associated with the manufacture, installation and maintenance of same. 
   According to one aspect of the present invention, there is a window frame having a lower portion. A window sash is constructed to be positioned within said window frame and capable of moving from a closed position to an open-tilted position, and vice versa. There is also a pair of parallel pivot pins on the window sash. A pair of kidney shaped receptacles is further disposed within said window frame which accommodate movement of the window sash from its said closed position to its open-tilted position and vice versa. 
   In accordance with a preferred embodiment of this aspect of the invention, in its open-tilted position, the window sash cooperates with the window frame so that the window sash abuts the window frame at its lower portion. The lower portion of the window frame limits the extent of the open-tilted position by preventing further movement of the window sash. 
   In accordance with a further embodiment of this aspect of the present invention, at least one parallel pivot pin of the pair of parallel pivot pins is retractable. 
   In accordance with a still further embodiment of this aspect of the present invention, an insertion channel is connected to at least one of the kidney shaped receptacles. The insertion channel permits the window sash to be inserted into the window frame in a tilted position when one of the parallel pivot pins engages the insertion channel, thereby allowing the window frame to move down into the kidney shaped receptacles and into a fully inserted position. 
   In accordance with yet another embodiment of this aspect of the present invention, the lower portion of the window frame that supports the window sash in its open-tilted position comprises a water dam. When the window sash abuts the water dam, the water dam prevents further movement of the window sash so as to define the maximum open-tilted position of the window sash. 
   In accordance with a still further embodiment of the present invention, the water dam further comprises an angular portion for supporting the window sash. 
   In accordance with a further embodiment of this aspect of the present invention, a sash stop is located on the window sash. The sash stop is similar to the sash stop commonly used to lift a window sash of a double hung window assembly. When the window sash is in an open-tilted position, the sash stop engages the surface of the window frame so as to limit the maximum open-tilted position of said window sash. 
   In accordance with another embodiment of this aspect of the present invention, the window sash further comprises a sash mating surface, and the window frame further comprises a frame mating surface. The said sash mating surface is arranged and constructed so as to be complementary to the frame mating surface. 
   In accordance with a still further embodiment of this aspect of the present invention, the surface of the window frame is a cam-like curved surface. 
   In accordance with another aspect of the present invention, a window assembly comprises a window frame, a window sash that has a connection means which is able to connect the window sash to the window frame so as to allow the window sash to attain a plurality of positions within the window frame, including an open-tilted and a closed position, a supporting means for supporting the window sash in an open-tilted position, and a pair of kidney shaped channels to receive the connection means. 
   In accordance with an embodiment of this aspect of the present invention, the supporting means is a water dam. 
   In accordance with an embodiment of this aspect of the present invention, the supporting means includes includes a sash stop. 
   In accordance with an embodiment of this aspect of the present invention, the connection means includes a pair of pivot pins. 
   In accordance with a further embodiment of this aspect of the present invention, the pair of pivot pins are retractable. 
   In accordance with another embodiment of this aspect of the present invention, the window sash further comprises a sash mating surface, and the window frame further comprises a frame mating surface. The said sash mating surface is arranged and constructed so as to be complementary to the frame mating surface. 
   In accordance with another aspect of the present invention, a window assembly comprises a window frame and a window sash constructed to be positioned within the window frame and capable of moving from a closed position to an open-tilted position. The window sash further has a pair of parallel pivot pins to accommodate movement of the window sash from its closed position to its open-tilted position and vice versa. There is also a dual function water dam located on the window frame, and a pair of channels located on the window frame. The dual function water dam serves two purposes. First, it limits the water permitted to enter a building through the window assembly caused during a rainstorm. Second, it provides support to the window sash when the window sash is in an open-tilted position. There are also two channels located on the window frame that are arranged and constructed to respectively receive each of the pivot pins. 
   In accordance with an embodiment of this aspect of the present invention, the channels are kidney shaped receptacles. 
   In accordance with another embodiment of this aspect of the present invention, the window sash further comprises a sash mating surface, and the window frame further comprises a frame mating surface. The said sash mating surface is arranged and constructed so as to be complementary to the frame mating surface. 
   In accordance with another aspect of the present invention, a window assembly comprises a window frame, a window sash having a plurality of angular positions within the window frame, including an open-tilted and a closed position, a first and second channel, a support means for supporting the window sash, and a connection means for connecting the window sash and the window frame. The window frame has a first horizontal arm, a second horizontal arm, a first vertical arm, and a second vertical arm. Similarly, the window sash comprises a first horizontal sash rail, a second horizontal sash rail, a first vertical sash rail, and a second vertical sash rail. The window sash is arranged and constructed for insertion into the opening of the window frame. The first channel is located on the first vertical arm of the window frame and a second kidney shaped channel is located on the second vertical arm. The channels are both capable of receiving a connecting means for connecting the window sash to the fixed frame. 
   In accordance with an embodiment of this aspect of the present invention, the connecting means is a pair of pivot pins. 
   In accordance with an embodiment of this aspect of the present invention, the support means for is a water dam. 
   In accordance with yet another embodiment of this aspect of the present invention, the support means for is a sash stop. 
   In accordance with another embodiment of this aspect of the present invention, the window sash further comprises a sash mating surface, and the window frame further comprises a frame mating surface. The said sash mating surface is arranged and constructed so as to be complementary to the frame mating surface. 
   In accordance with another aspect of the present invention, a window assembly comprises a fixed window frame, a kidney shape channel, a window sash arranged and constructed so as to be inserted into the window frame, and further having an open-tilted position and a closed position, and a support means for supporting the window sash when the window sash is in an open-tilted position. The window frame has a first horizontal arm, a second horizontal arm, a first vertical arm, and a second vertical arm. The window sash comprises a first horizontal sash rail, a second horizontal sash rail, a first vertical sash rail, and a second vertical sash rail. The window sash also has a pin located in one of the vertical sash rails. The pin is received by the kidney shaped channel that is located in at least one vertical arm of the fixed window frame. 
   In accordance with another embodiment of several aspects of the present invention, the only connection between the window sash and the window frame is the pair of parallel pivot pins, such that the window sash can be easily removed from the window frame. 
   These and other features and characteristics of the present invention will be apparent from the following detailed description of preferred embodiments which should be read in light of the accompanying drawings in which corresponding reference numbers refer to corresponding parts throughout the several views. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of a preferred window assembly according to the present invention. 
       FIG. 1A  is a rear perspective view of the preferred window assembly shown in  FIG. 1  according to the present invention. 
       FIG. 2  is a front view of a preferred window frame according to the present invention. 
       FIG. 3  is a cross sectional view of the left window jamb of the window frame in  FIG. 2 . 
       FIG. 3A  is a cross sectional view of the right window jamb of the window frame in  FIG. 2 . 
       FIG. 4  is a cross sectional cut-away view of the lower portion of the left window jamb of the window frame in  FIG. 2 . 
       FIG. 4A  is a cross sectional cut-away view of the lower portion of the right window jamb of the window frame in  FIG. 2 . 
       FIG. 5  is a front view of the preferred window sash shown in  FIG. 1 . 
       FIG. 6  is a perspective view of the installation of a window sash into a window frame, as shown in  FIG. 1 , according to the present invention. 
       FIG. 7  is a cross-sectional view of the left window jamb of the window frame shown in  FIG. 1  and a preferred window sash shown in  FIG. 1  in a closed position. 
       FIG. 8  is a cross sectional view of the right window jamb of the window frame shown in  FIG. 1  and the preferred window sash in a closed position. 
       FIG. 9  is a cross sectional view of the right window jamb of the window frame shown in  FIG. 1  and the preferred window sash in an open position. 
       FIG. 10  is a cross sectional view of the left window jamb of the window frame shown in  FIG. 1  and the preferred window sash in an open position. 
       FIG. 11  is a front view of an alternative embodiment of a window assembly according to the present invention. 
       FIG. 12  is a cross-sectional cut-away view of the alternative embodiment shown in  FIG. 11  of the second vertical window jamb and an alternative embodiment of a preferred window sash in a closed position. The first vertical window jamb (not shown) of the window sash can be a mirror image of the second vertical window jamb. However, it is not necessary that the first vertical window jamb have an insertion channel connected to the kidney shaped receptacle. 
       FIG. 13  is a cross-sectional cut-away view of the alternative embodiment shown in  FIG. 11  of the right window jamb and the alternative embodiment of a preferred window sash in an open-tilted position. 
       FIG. 14  is a front-view of a window sash assembly according to another embodiment of the present invention. 
       FIG. 15  is a side view of the window sash shown in  FIG. 14 . 
       FIG. 16  is a cross-sectional cut-away view of the right window jamb of an alternative window frame assembly and the window sash shown in  FIG. 14  in its closed position. 
       FIG. 17  is a cross-sectional cut-away view of the left window jamb of the window frame assembly shown in  FIG. 16  and the window sash shown in  FIG. 14  in its closed position. 
       FIG. 18  is a cross-sectional cut-away view of the right window jamb of the window frame assembly shown in  FIG. 16  and the window sash shown in  FIG. 14  in its open-tilted position. 
       FIG. 19  is a cross-sectional cut-away view of the right window jamb of the window frame assembly shown in  FIG. 16  and the sash shown in  FIG. 14  in its open-tilted position. 
   

   DETAILED DESCRIPTION 
   The present invention is generally directed to a window assembly  100 , such as the window assembly  100  shown in  FIGS. 1 and 1A . The window assembly  100  is preferably comprised of a window frame  102 , and a window sash assembly  104  that has pivot pins  500  and a glass window unit or windowpane  106 . The window assembly  100  is constructed and arranged so that the window sash assembly  104  and window frame  102  cooperate with one another to permit the rotation of the window sash assembly  104  relative to the window frame  102 . Specifically, as shown in  FIG. 1A , pivot pins  500  are able to move within kidney shaped receptacles  210  located on the window frame  102  that guide the tilting movement of the window sash assembly  104  relative to the window frame  102 . The window sash is therefore able to achieve a plurality of positions, including an open-tilted and closed position. While the present invention will be described primarily with respect to a single-hung window assembly, it should, however, be appreciated that the present invention can be used in connection with various other types of pivotal windows or structures including, but not limited to, a double-hung window assembly, a vertical pivot window assembly, and the like, wherein it is desired to install a window that is efficient in terms of time and cost. 
   The window frame  102  comprises a plurality of members joined together at their respective ends. As shown in  FIG. 2 , the header  202  is joined at a first end  218  with a second end  232  of the left window jamb  206 . At its second end  220 , the header  202  is joined with the first end  222  of the right window jamb  208 . The second end  224  of the right window jamb  208  is joined with the first end  226  of footer  203  (see  FIG. 1A ). At its second end  228 , the footer  203  is joined with the first end  230  of the left window jamb  206 . 
   As seen in  FIGS. 1A and 2 , the water dam  204  is located in front of footer  203  so as to prevent water, wind, or other elements of the outdoors from invading the interior of a building. As will be discussed in greater detail herein, the water dam  204  may also serve as a means for supporting the window sash in its open-tilted position. It should be appreciated, however, that the water dam  204  may be integrally formed with the footer  203  in order to save on the cost of materials during manufacture of the window frame  102 . 
   Referring to  FIG. 2 , a sash support  207  is located inwardly of the water dam  204  (see also  FIG. 1A ) and extends the length around the left window jamb  206 , header  202 , and right window jamb  208  of the window frame  102 . The sash support  207  supports the window sash  104  (see  FIG. 1A ) when the window sash  104  is in its closed position. It should be appreciated that the sash support  207  need not extend the length of left window jamb  206 , header  202 , and right window jamb  208  of the window frame  102 , nor does it need to be located on all three parts of the window frame  102 . 
   An important feature of the present invention is best shown in  FIGS. 3-3A , which are cross-sectional views of the left window jamb  206  and right window jamb  208 , respectively. Specifically, a pair of kidney shaped receptacles  210 ,  212  are located on the lower regions of the left window jamb  206  (see  FIG. 3 ) and right window jamb  208  (see  FIG. 3A ), respectively, as well as, close to the water dam  204 . The kidney shaped receptacles have an upper kidney end  304  and a lower kidney end  302 . As shown in  FIG. 3A , there is an insertion channel  214  located on the right window jamb  208  that is connected to the upper kidney end  304  of the kidney shaped receptacle  212 . Additionally, there is a transition region  402 , located at the beginning of the insertion channel  214 . It should be appreciated that the insertion channel  214  may instead be located on the left window jamb, or alternatively on both left and right window jambs  206 ,  208 . As can be seen in  FIG. 2 , the kidney-shaped receptacles  210 , 212  are disposed in a line substantially in parallel with the footer  203  to provide for tilting movement of the window sash  104  by means of the pivot pins  500 . 
   Referring back to  FIG. 2 , the depth D 1  of the kidney shaped receptacles  210 , 212  ranges from 0.325-0.425 inches. The depth D 2  of the insertion channel  214  is dependent upon the depth of the kidney shaped receptacle  212  to which the insertion channel  214  is connected. Accordingly, the depth of the insertion channel  214  will also range from 0.325-0.425 inches. The depth of the transition region  402  of the insertion channel  214  is gradually shallower in depth than the remainder of the insertion channel  214 . However, at the point where the transition region  402  and insertion channel  214  meet, the depth of the transition region  402  will equal the depth of the insertion channel  214 . 
     FIGS. 4 and 4A  show cross-sectional cut away portions of the lower portions of the left and right window jambs  206 , 208  that illustrate the kidney shaped receptacles  210 , 212  and insertion channel  214  in greater detail. In a preferred embodiment, the radii R 1  of the upper and lower kidney ends  302 , 304  of the kidney shaped receptacles  210 , 212  preferably range from approximately 0.20-0.30 inches. The length L 1  of the kidney shaped receptacles ranges from approximately 0.725-0.825 inches, and the width W 1  of the kidney shaped receptacles  210 ,  212  ranges from 0.45-0.55 inches. As shown in  FIG. 3A , the insertion channel  214  that connects to the kidney shaped receptacle  212  on the right window jamb  208  has a length ranging from 5 to 10 inches, and a width ranging from 0.45-0.55 inches. 
   As shown in  FIG. 4A , the insertion channel  214  has several curves at or near the point where it intersects the kidney shaped receptacle  212 . It is believed that such a configuration enables greater ease during installation and mounting of the window sash assembly  104  (see  FIG. 1A ) within the window frame  102 , as it helps to facilitate movement of the pivot pin  500  through the insertion channel  214  and into the kidney shaped receptacle  212 . 
   A lower inner curve  410  is formed at the point where the insertion channel  214  is connected to the kidney shaped receptacle  212 . The lower inner curve  410  has a radius of curvature R 3  ranging from 0.075-0.175 inches. An intermediate curve  450  is located above the lower inner curve  410  and adjacent to the open-tilt support  300 . Intermediate curve  450  has a radius of curvature R 4  ranging from approximately 0.20-0.30 inches. A right insertion channel curve  430  is located above the intermediate curve  450  and has a radius of curvature R 6  ranging from approximately 0.075-0.175 inches. A left insertion channel curve  440  is located above the upper inner curve  420  and has a radius R 5  ranging from approximately 0.20-0.30 inches. It should be appreciated, however, that the aforementioned dimensions of the kidney shaped receptacles  210 ,  212  and insertion channel  214  may vary based on the size of the window frame. Additionally, in insertion channel may have more or fewer curves without departing from the scope of the present invention. 
   A preferred window sash assembly  104  according to the present invention is shown in  FIG. 5 . The window sash assembly  104  is formed by the union of the left sash rail  502 , right sash rail  504 , upper sash rail  506 , and lower sash rail  508  (see  FIG. 1A ) at their outermost ends. The pivot pins  500  are located on the outer portion of opposed lower ends of the window sash assembly  104 . The window pane  106  is embedded in the window sash assembly  104 . The window pane  106  may be comprised of any number of materials, such as plastic, glass, or a screen material. 
   Based on these features of the window sash assembly  104  and window frame  102 , mounting of the window sash assembly  104  into the window frame  102  is easily accomplished as compared with prior art windows which require the installation and assembly of additional window assembly parts. Referring to  FIG. 6 , the window sash assembly  104  is mounted on the window frame  102  by first horizontally tilting the window sash assembly  104  so that the right sash rail  504  is higher than the left sash rail  502 . The pivot pin  500  located on the right sash rail  504  is then placed into the transition region  402  of the insertion channel  214 , while the pivot pin  500  located on the left sash rail  502  is placed into and engages the kidney shaped channel  210  located on the left window jamb  206 . Once the pivot pin  500  located on the left window jamb  206  is secured within the kidney shaped receptacle  210 , the pivot pin  500  located on the right window jamb  208  is able to slide into the insertion channel  214 , beginning at the transition region  402 . Due to the transition region  402 , the pivot pin  500  of the window sash assembly  104  is able to easily move through the insertion channel  214 , and down into the kidney shaped receptacle  212  on the right window jamb  208 . 
   In an alternative embodiment of a window assembly  100  of the present invention, retractable pins, which could be the pins  500 , can be used on either or both the left and right sash rails  502 ,  504 . The retractable pins can be retracted into the window sash assembly  104 , such that during window assembly, it is unnecessary to horizontally tilt the window sash assembly  104  so as to allow a pin to engage the insertion channel  214 . Instead, retraction of the pins allows the window sash assembly  104  to fit directly into the opening of the window frame  102 , such that the pivot pins  500  are able to easily engage the kidney shaped receptacles  210 , 212 . This configuration eliminates the need for the construction and arrangement of the insertion channel  214  in the right window jamb  208 . Accordingly, in such a configuration, only the kidney shaped receptacles  210 , 212  need be located on the lower regions of the left and right window jambs  206 ,  208 . 
   Referring to  FIGS. 7-10 , when mounted in the window frame  102 , the window sash assembly  104  is capable of achieving a plurality of angular positions. However, the kidney shaped receptacles  210 ,  212  advantageously permit the window sash assembly to achieve two stationary or stable positions. A lower stable position provides a fully closed window, and a higher stable position provides a sufficient tilt-opening when a water dam is employed. Accordingly, the window sash assembly  104  has a stable closed position, and a stable open-tilted position. It should be further appreciated that the window can also maintain various stable angular positions due to further construction and arrangement of the window assembly, without departing from the spirit and scope of the present invention. 
   The window sash assembly  104  is in a non-pivoted or closed position when it rests within the left and right window jambs  206 , 208  of the window frame  102 . As shown in  FIGS. 7 and 8 , this occurs when the pivot pin  500  of the left and right sash rails  502 , 504  (see  FIG. 6 ) engage the lower end  302  of the kidney shaped receptacles  210 ,  212  of the left and right window jambs  206 , 208  respectively. The window sash assembly  104  can then be locked in the window frame  102  when the left lock control  512  (see  FIG. 5 ) and right lock control  513  manipulate a locking mechanism, such as a lock pin (not shown), to engage the lock openings  216  (see  FIG. 2 ) of the window frame  102 . Use of the two handles is advantageous to better secure the window frame, as well as, to help better insulate a building against the outdoor elements, such as wind and water. Alternatively, one lock control may be utilized to secure the window sash. In such an alternative embodiment, the lock control is preferably located in the center of the upper rail of the window sash assembly  104 . 
   Referring to  FIGS. 9 and 10 , the window sash assembly  104  is in an open-tilted stationary position when the window sash assembly  104  is at its maximum open position. This occurs when the pivot pins  500  of the left and right sash rails  502 , 504  engage the upper kidney end  304  of the kidney shaped receptacles  212  of the right and left window jambs  206 , 208 . Additionally, in another important feature of the present invention, a support means is provided for holding the window sash assembly  104  in its open-tilted position. In a preferred embodiment, a water dam  204  is used to support the window sash assembly  104  in its open-tilted position. As such, the water dam  204  serves a dual purpose. First, it is a water barrier that minimizes the amount of water that may enter the interior of a building during a rainstorm. Second, it is a support for the window sash assembly  104  when the window sash assembly  104  is in its open tilted position. 
   The window sash assembly  104  will rest on the open-tilt support  300 , of the water dam  204 , so as to maintain an open-tilted position. The open-tilt support  300  preferably provides a flat surface at an angle that mates with the window sash. In a preferred embodiment, the height of the water dam  204  ranges from 1-2 inches. It should be appreciated that the height of the water dam  204  and/or angle of the open tilt-support  300  can be varied in order to alter the maximum open-tilted position of the window sash assembly  104 . This may be especially advantageous if the window assembly  100  is to be located above a tall object and it is desired to position the window such that it will not contact the object when in its open-tilted position. 
   Referring to  FIGS. 11-13 , an alternative embodiment for a window assembly  1100  according to the present invention is shown.  FIG. 11  shows a front view of an alternative window assembly  1100  according to the present invention comprising a window frame  1102  and a window sash assembly  1104 . The window sash assembly  1104  is comprised of a left sash rail  1106 , a right sash rail  1108 , an upper sash rail  1110 , and a lower sash rail  1112 , each joined together at their respective ends, pivot pins (not shown), a sill lift  1114  located across the bottom of the window sash assembly  1100 , and right handle  1150  and left handle  1151 . The sill lift  1114  is constructed and arranged similar to the sill lift handle commonly utilized in a double hung window assembly. Such sill lifts are manually used to lift a window into an open position. The window jambs include cooperating kidney shaped channels, one kidney shaped channel  1210  in a first vertical window jamb  1116 , and one kidney shaped channel  1200  (see  FIG. 12 ) in a second vertical window jamb  1118 . The window frame  1102  further includes an upper border  1120 , and a lower border  1121  (See  FIG. 12 ). A water dam  1122  is located in front of said lower border  1121 , and is integrally formed with said lower border  1121 . It should be appreciated, however, that the water dam  1122  may be formed separately from the lower border  1121 . 
   Referring to  FIG. 12 , there is a cross-sectional cut-away view of the window sash assembly  1104  located in its closed position within a first vertical window jamb  1116  and a second vertical window jambs  1118  (see  FIG. 11 ), of the window frame  1102 . A kidney shaped receptacle  1200  is shown in the lower region of the second vertical window jamb  1118  (see  FIG. 11 ). An insertion channel  1202  connects to the kidney shaped receptacle  1200  in the second vertical window jamb  1116 . 
   A corresponding kidney shaped receptacle  1210  (see  FIG. 11 ) is located on the first vertical window jamb  1116  without the insertion channel  1202 . However, it should be appreciated that the first vertical window jamb  1116  can be constructed and arranged so as to be a mirror image of the second vertical window jamb  1116 , thereby having an insertion channel  1202 . 
   Referring to  FIG. 13 , a cross-sectional cut-away view of the window sash assembly  1104  is shown in its open-tilted position. The pivot pins  500  engage the upper kidney end  1206 . The sill lift  1114  rests against the water dam  1122 , which preferably has a cam-shaped supporting surface  1123 , so as to support the window sash assembly  1104  in its open-tilted position. 
   Referring to  FIGS. 14-19  there is shown an alternative window assembly according to the present invention comprising a window sash  1400  (See  FIGS. 14 and 15 ) and a window frame  1600  (See  FIG. 16 ). In addition to the typical components of a window sash, such as the top, bottom, right and left sash rails, the window sash further comprises a sash mating surface  1402 . As shown in  FIG. 15 , the sash mating surface  1402  comprises an inner edge  1404  and a sash curve  1406 . 
   The window frame  1600  shown in  FIGS. 16-19  comprises a header (not shown), a right window jamb  1410  (See  FIG. 16 ), a left window jamb  1412 (See  FIG. 17 ), a footer  1604 , and a water dam  1606 . The footer  1604  and water dam  1606  are preferably formed from a unitary piece of material such that there is a uniform frame mating surface  1602 . The water dam  1606  is greater in height than the footer  1604 , such that the frame mating surface  1602  has an angular slope that is complementary to the sash mating surface  1402  (see  FIG. 15 ). The angular slope of the frame mating surface  1602  preferably has a radius of curvature R10 ranging from 0.388-0.488 inches. There is also a frame mating edge  1608  located at the top of the water dam  1606 . At the point where the frame mating edge  1608  of the frame mating surface  1602  connects with the remainder of the frame mating surface  1602 , there is an upper radius of curvature R 12  preferably ranging from 0.15-0.20 inches. 
   As shown in  FIGS. 16 and 17 , the window frame is further characterized by kidney shaped receptacles  1610 ,  1611  respectively located on the right and left window jambs  1410 ,  1412  that receive the pivot pins  1401  of the window sash  1400 . The center C 1  of the lower kidney end  1616  of the kidney shaped receptacles  1610 ,  1611  is located approximately 1.2 inches from the base of the footer  1604 . The center C 2  of the upper kidney end  1618  is displaced approximately 0.031 inches from C 1 . 
   Referring to  FIG. 16 , on the right window jamb  1410 , there is an insertion channel  1612  (that connects to the kidney shaped receptacle  1610 . Accordingly, a connection curve  1614  is formed at the point where the kidney shaped receptacle  1610  and insertion channel  1612  meet. In a preferred embodiment, the connection curve  1614  has a radius of curvature R 14  ranging in size from 0.045-0.55 inches. 
   The insertion channel  1612  of this alternative embodiment is similar in function to the insertion channel  214  of  FIGS. 2 and 3A . It should be appreciated that there are slight differences between the insertion channel  1612  and insertion channel  214  of  FIGS. 2 and 3A . For example, the displacement between C 1  and C 2  is 0.045, whereas the displacement between A 1  and A 2  of  FIGS. 2 and 3A  is 0.068. Additionally, there are fewer radii of curvature in the present embodiment, as compared to  FIGS. 2 and 3A . Despite such differences, both embodiments fall within the scope of the present invention. 
   The window assembly  1400  has two stationary positions, an open-tilted and a closed position. As shown in  FIGS. 16 and 17 , in its closed position, the sash mating surface  1402  of the window sash  1400  is complementary to the frame mating surface  1602  of the window frame  1600 . Furthermore, the pivot pins  1407  are located in the lower kidney ends  1616 . 
   Referring to  FIGS. 18 and 19 , in its open-tilted position, the pivot pins  1401  are located in the upper kidney ends  1618 . The window sash is able to maintain a stable and open-tilted position when the inner edge  1404  of the window sash  1400  rests on top of or over the frame mating edge  1608  of the water dam  1606 . 
   Although the invention herein has been described with reference to particular embodiments and preferred dimensions or ranges of measurements, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. Additionally, it is to be appreciated that the present invention may take on various alternative orientations. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.