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BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention generally relates to window latches. More specifically, it is concerned with window latches that can be quickly operated to open a window to allow fast, free egress through said window, especially in an emergency situation such as a fire. Windows that employ such latches will normally be located in the walls of a room. Such windows could, however, also be located in building roofs and thereby serving as skylights for lofts, attics and the like. 
         [0003]    2. Discussion of the Background 
         [0004]    Windows for emergency exit use are well known. For example, European Patent Application No. 0 329 315 A1 discloses a pivotally mounted window that, upon actuation of a control handle, releases a catch in order to disengage the lower ends of arms located in the vertical components of a window sash. Forces applied by gas driven springs then act upon the arms in such a manner that said arms move outwardly about a hinged axis in an upper horizontal component of the window sash and thereby forcing the window sash outward and clear of the window frame to create an emergency exit. 
         [0005]    U.S. Pat. No. 5,056,262 discloses a window guard screen and frame assembly installed on the jamb of a building window in a manner that prevents unauthorized external access, but permits quick egress from within the building through the window in case of an emergency such as a fire. A screen can be fabricated from a metal sheet whose margins are folded inward to define channel-like ends and side branches bordering a planar field. The frame is dimensioned to overlie and nest within the window jamb to which the window is secured. Integral with the inner surface of the frame and bordering the opening therein is a slideway socket for receiving a screen. The socket is defined by end and side legs which complement the branches of the screen. Hinge pins are mounted on the end legs of the slideway socket adjacent to one of the side legs. These pins extend through elongated slots formed in corresponding end branches of the screen. The screen is slidable to an extent that is limited by the slots from a security mode position in which the screen is confined to the socket. The egress mode screen is free to swing on the hinge pins out from the frame opening and thereby permitting exit through the window. A releasable latch is mounted on the opposing side leg of the socket to engage a corresponding side branch of the screen to lock the socketed screen in its locked, security mode position. When released, the latch permits the screen, which is spring loaded, to slide to its fast egress permitting mode. 
         [0006]    These prior art fast egress systems have latch systems that are activated by small levers located on the window sash. Such levers may be difficult to find and actuate using only the strength of human fingers, especially under emergency conditions. Moreover, many prior art latch systems may be subject to being inadvertently relocked under the human stress normally attendant to dealing with an emergency situation. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a free egress window latch system that is especially designed for fast egress from a room, especially under emergency conditions such as a fire. Applicant&#39;s free egress latch system also serves to prevent inadvertent relocking of the window from the outside. The free egress latch system of this patent disclosure can be mounted in a room wall adjacent to a hinged window having a latch pin that protrudes from an adjacent vertical component of a window sash so that the latch pin can cooperate with the free egress latch system in a manner hereinafter more fully described. 
         [0008]    The latch system of this patent disclosure has a housing component that can be rectangular, square, etc. as far as its exterior shape is concerned. In any case, the housing component contains a latch pin receiving mechanism that includes a latch cam that, upon actuation, becomes capable of a rocking motion that serves to release the window latch pin from the grip of the latch cam. The latch cam is provided with three distinct camming surfaces whose respective functions are hereinafter more fully described. The housing component further comprises a tubular sleeve component that houses a push rod whose first end is mechanically connected to the latch pin cam. The opposing end of the push rod terminates in an actuator such as a push knob that protrudes from a room wall adjacent to the window served by Applicant&#39;s free egress latch system. 
         [0009]    In an emergency situation such as a fire, a human being can push an actuator (such as a push knob) inwardly (i.e., toward the outside wall of the building) with the palm of his/her hand. This pushing action is naturally aided by the weight of that person&#39;s body. The resulting pushing action is therefore inherently more powerful than a twisting and/or pulling action by human fingers. The actuator (e.g., push knob) can be brightly colored (red, orange, yellow, etc.) for ease of identification in an emergency situation. Pushing on the window to be opened and the actuator (push knob) at the same time will further facilitate a fast opening of the window. Thus, the occupants of the room in which the actuator is located can quickly exit the room through the now opened window. 
         [0010]    Next, it should be noted that the housing is also provided with a slot that allows passage of a latch pin into/out of the interior region of said housing. An opposing end of the housing is provided with a hole that allows passage of a push rod into/out of the interior region of the housing. A latch cam, capable of clockwise/counterclockwise motion about an axle upon which said latch cam is rotatably mounted, is positioned in the housing in a manner such that it can mechanically cooperate with the latch pin. This latch cam is further provided with (i) a first hole through which the axle passes, (ii) a top camming surface for pressing against a cam pressure plate, (iii) a concave inner cam region for receiving the latch pin, (iv) a latch pin blocking surface that prevents the latch pin from returning to the concave inner cam and (v) a second hole in which a push rod end is mounted. 
         [0011]    An axle mounted in the interior of the housing has a diameter smaller than the diameter of the first hole in the latch cam through which the axle passes and thereby allowing clockwise/counterclockwise motion of the latch cam about the axle. A cam receiver plate that is biased against the top camming surface of the latch cam by a biasing device such as a spring. A tubular sleeve is affixed to the housing. This tubular sleeve contains a push rod whose inner end is connected to the second hole in the latch cam and whose outer end is connected to a push knob located in a room next to the window being served by this free egress system. A push knob is adapted and arranged to receive pressure from a human hand in order to force the push rod toward the housing and thereby rotate the latch cam about the axle and release the latch pin from the concave inner cam region of the latch cam. 
         [0012]    This free egress latch system is also particularly characterized by the fact that once the latch pin has been released from the grip of the latch pin cam, the latch pin can not inadvertently return to the latch pin receiving region of the latch cam and thereby relocking the window shut and thus preventing re-entry into the room through the window by rescue personnel. In order to deliberately re-engage the latch pin of the window with the latch pin cam of the free egress latch system, the push knob must be pushed inwardly from within the room Normally this would be done after the emergency condition was over and the return of normal conditions would call for the window to be relocked. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of the free egress latch of this patent disclosure shown positioned next to a vertical element of a window sash having a latch pin with which the free egress latch cooperates. 
           [0014]      FIG. 2  is a front view of a window that is served by Applicants free egress latch system. 
           [0015]      FIG. 3  is a cross sectional view of the free egress latch and a window that cooperates with said latch. 
           [0016]      FIG. 4  is also a cross sectional view of the free egress latch shown with the window sash and its associated latch pin disengaged from the free egress latch system. 
           [0017]      FIG. 5  is a cross sectional view of the free egress latch engaged with the latch pin of the window sash. 
           [0018]      FIG. 5A  is a cross sectional view of an alternative embodiment of this invention wherein the cam has a different configuration from the cam depicted in  FIG. 5 . 
           [0019]      FIG. 6  is a cross sectional view of the free egress latch as the latch pin of the window sash is being disengaged from the latch cam component of the free egress latch system. 
           [0020]      FIG. 7  is a cross sectional side view of the free egress latch in a position such that it is blocking the window latch pin from inadvertently re-engaging with the latch pin locking region of the latch cam. 
           [0021]      FIG. 7A  is a cross sectional side view of the alternative embodiment of  FIG. 5A  performing its latch pin blocking function. 
           [0022]      FIG. 8  is a cross sectional side view of the free egress latch that depicts the cam in pressured contact with a spring biased pressure plate. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]      FIG. 1  is a perspective view of various outer features of a free egress latch system constructed, adapted and arranged according to the teachings of this patent disclosure. The inner features of said system will be illustrated in subsequent  FIGS. 3-8 . This latch system  10  is mounted between an outside wall  12  and an inside wall  14  of a building not otherwise shown. The mounting of this latch system  10  could, for example, be achieved through use of a mounting bracket such as the L-shaped mounting bracket  16  depicted in  FIG. 1 . As previously noted this latch system  10  could also service a skylight type window in a building roof or a door. However, a wall mounted system used in conjunction with a window will be used as an illustrative example throughout this patent disclosure. 
         [0024]    The latch system  10  of  FIG. 1  is shown provided with a rectangular housing component  18  whose top four corners are respectively indicated by the numbers  20 ,  22 ,  24  and  26 . Again, this housing component  18  could have other shapes (e.g., square, ellipsoidal, etc.), but a rectangular shape will be used for purposes of illustration. The latch system  10  also has a tubular sleeve component  28 . This tubular sleeve component  28  is depicted as having a round cross-section, but it could just as well have a square, rectangular, etc. cross section. The tubular sleeve component  28  is securely affixed to the  20 - 22  side of the rectangular housing component  18  (e.g., by being welded, threaded, etc. thereto). The tubular sleeve component  28  houses a push rod  42  that is affixed to a human hand-operated actuator such as a push knob  54 . 
         [0025]    The  24 - 26  side of the rectangular housing component also can have an opening that facilitates free passage of a window latch pin  13  into and out of the interior of the housing component  18  wherein various moving components of a latch mechanism, hereinafter more fully described, are located. The  20 - 26  side of the rectangular housing  18  contains a slot  15  that allows passage of the window latch pin  13  into and out of (as suggested by two-headed arrow  17 ) the interior of the rectangular housing component  18 . The  24 - 26  side of the housing also contains a perpendicular extension of the slot  15  in the  20 - 26  side of the housing  18 . This perpendicular extension is designated as item  15 A. The window latch pin  13  is mounted in a vertical element of a window sash  19 . Such a window sash  19  could, for example, contain a mesh screen, a glass pane, etc. An anti-tampering plate is also shown attached to the vertical element of the window sash  19 . 
         [0026]      FIG. 2  is an elevation view of a hinged window (containing a pane of glass, mesh cover, screen, etc.) whose hinged end is, for example, shown provided with three window hinges H( 1 ), H( 2 ) and H( 3 ). The unhinged end of the window sash is provided with the latch system of this patent disclosure. A cross sectional view indicated by cross section lines A-A is depicted in  FIG. 3 . Cross sectional view B-B is depicted in  FIG. 5 . 
         [0027]      FIG. 3  is the A-A cross sectional view of the free egress latch system  10  illustrated in  FIG. 1 . Again, this latch system  10  is mounted between an outside wall  12  and an inside wall  14  of a building not otherwise shown. As noted in the discussion of  FIG. 1 , the mounting of the latch system  10  to a building may, for example, be achieved through use of a mounting bracket such as the L-shaped mounting bracket  16  depicted in  FIG. 1 . Here again, the latch system of  FIG. 3  is depicted with a rectangular housing component whose four corners in this view are respectively indicated by the numbers  20 ,  22 ,  24  and  26 . The latch system  10  also has a tubular sleeve component  28  whose, by way of example, cross sectional corners are indicated by the numbers  30 ,  32 ,  34  and  36 . The tubular sleeve component  28  is firmly affixed to the  20 - 22  side of the rectangular housing component  18  (e.g., by being welded, threaded, etc. thereto). The  20 - 22  side of the rectangular housing component  18  is also provided with a hole  38  that allows free reciprocal motion (depicted by two-headed arrow  40 ) of the push rod  42  that generally resides inside of the tubular sleeve component  28 . The indoor end  44  of the tubular sleeve component  28  and the push rod  42  are shown protruding out of a hole  47  in the inside wall  14 . The end of the push rod is shown covered by a push knob  54 . The tubular sleeve  28  and push rod  42  may be cut to the desired length in the field to suit the thickness of the wall in which this free egress latch system is mounted. The indoor end  44  of the tubular sleeve component  28  also, for esthetic reasons, can be covered by an escutcheon  46 . Such an escutcheon  46  may have the general configuration of a cup portion  46 A surrounded by a rim portion  46 B. The bottom of the cup portion of the escutcheon  46  is shown provided with a hole  46 C through which the push rod  42  can freely pass. The rim portion  46 B of the escutcheon  46  may be provided with holes  46 D and  46 E that will pass screws or other fasteners that can attach the rim  46 B of the escutcheon  46  to the face of the inside wall  14 . 
         [0028]    The inside end of the push rod  42  is shown provided with an attachment mechanism for attaching the inside end  50  of the push rod  42  to a push knob  54 . To this end the inside end  50  of the push rod  42  is shown provided with threads  52 . When an outwardly directed force  56  (e.g., such as a force applied by a human hand) is placed upon the push knob  54 , the push rod  42  is forced outwardly (i.e., toward outside wall  12 ). The opposite end of the push rod  42  has an L-shaped end  42 A that passes through a hole  58  in a pivotally mounted latch cam  60 . The pivotally mounted latch cam  60  has a second hole  62  through which an axle  64  passes. The axle  64  has a diameter smaller than the hole  62  in the latch cam  60  through which the axle  64  passes. This circumstance allows the cam  60  to freely rotate about the axle  64  and thereby allow a clockwise/counterclockwise or “rocking” motion of the latch cam  60  about the axle  64  when a force  56  is applied to—and released from—the push knob  54 . As better seen in  FIG. 8 , a first end of the axle  64  is anchored (e.g., by welding, threading, etc.) to the  20 - 24  side of the rectangular housing component  18 . The opposite end of the axle  64  is similarly affixed to the  22 - 26  side of the rectangular housing component  18 . It also should be noted that section lines  5 - 5  of  FIG. 3  show the view depicted in  FIG. 5 . 
         [0029]      FIG. 4  is also a cross sectional view of the free egress latch system  10  wherein the window latch pin  13  is shown completely free of the latch cam  60  as the window is being opened. This view also better illustrates the placement of, and function of, the anti-tampering plate. In effect, the anti-tampering plate  23  covers the opening  11  in the  24 - 26  side of the housing  18 . This anti-tampering plate  23  serves to thwart a would-be burglar from gaining access to the interior of the latch housing and, hence, the locking mechanism contained therein. 
         [0030]      FIG. 5  depicts the B-B cross sectional view suggested in  FIG. 2 . It illustrates that the latch cam  60  contains a hole  62  in which the axle  64  resides. The hole  62  in which the axle resides is depicted as being located in a more or less central region  65  of the latch cam  60  which, by way of example, is shown as having a generally crescent shaped body. Again, the axle  64  is stationary by virtue of its ends being affixed (e.g., by welding, threading) to opposing walls of the rectangular housing component  18  in the manner generally illustrated in  FIG. 8 . As previously noted, the diameter of the axle  64  is smaller than the diameter of the hole  62  in the latch cam  60 . Thus, the latch cam  60  is capable of a rocking motion (generally depicted by curved, two-headed arrow  61 ) about the axle  64  under a force  56  delivered from the push knob  54  to the latch cam  60  via the push rod  42  whose L-shaped end  42 A resides in a second hole  58  in the lower end of said latch cam  60 . In effect,  FIG. 5  shows the latch cam  60  in a first operating position wherein no force  56  is being applied to the push rod  42  from the push knob  54 . In this first operating position the latch pin  13  resides in a concave inner cam region  68  of the latch cam  60 . This concave inner cam region  68  may also be referred to as a “first surface” in this patent disclosure and/or its claims. Be that as it may, a “nesting” of the latch pin  13  in this concave inner cam region  68  serves to hold the window sash  19  depicted in  FIGS. 1 and 3  in its closed, locked mode.  FIG. 5  also illustrates how the inner cam region  68  leads to an outer cammed surface  70  over which the latch pin  13  will slide (e.g., in the manner suggested in  FIG. 6 ) as the latch cam  60  is forced to a second operating position illustrated in  FIG. 6 . 
         [0031]      FIG. 5  also illustrates that the interior of the housing  18  also contains a post  72  about which a coil spring  74  is positioned. As will be seen in  FIG. 8 , there are in fact two such posts  72 A and  72 B and two such springs  74 A and  74 B. In any case, the post  72  of this  FIG. 5  is shown affixed to a shaft anchor plate  76  whose ends are, in turn, affixed to opposing walls of the rectangular housing  18  in the manner depicted in  FIG. 8 . In an alternative embodiment of this invention, the anchoring plate  76  can be removed and the bolt end  79  can be attached (by welding, threading, etc.) to the inside surface  83  of the  20 - 26  side of the housing  18 . The post  72  can be readily created by use of a machine bolt whose head is depicted as item  80 . The opposite end  79  of the bolt post  72  is shown passing through the anchor plate  76 . Next, it should be noted that a moveable cam pressure plate  78  is mounted between the bolt head  80  and the end  77  of the spring  74 . The cam pressure plate  78  has a hole  81  through which the bolt post  72  passes. In the first operating position depicted in  FIG. 5 , the spring  74  is at its fully extended position such that the cam receiver plate  78  is positioned at a level  82  that is commensurate with the fully extended position of the spring  74 . In this position the left side  73  of the latch cam  60  comes into abutting contact with a stop  66 . This left side  73  generally presents a flat surface rather than a cammed surface. In this first operating position the coil spring  74  is biasing the latch cam  60  in a clockwise direction  75 . Hence the push rod  42  is biased in the leftward direction suggested by direction arrow  57 . Section lines  8 - 8  create the view seen in  FIG. 8  of this patent disclosure. 
         [0032]      FIG. 5A  depicts an alternative embodiment of this invention wherein the shape and mounting position of the latch cam  60 A differ somewhat from the shape and positioning of the latch cam  60  shown in  FIG. 5 . For example, in  FIG. 5 , the inner cam region  68  leads to an outer cammed (i.e., curved) surface over which the latch pin  13  will slide (e.g., in the manner generally suggested in  FIG. 6 ) as the latch cam  60  is forced to a second operating position illustrated in  FIG. 6 . By way of contrast, in  FIG. 5A , the outer cammed (i.e., curved) surface  70  of  FIG. 5  has been changed to the generally flat surface  70 A depicted in  FIG. 5A . Thus, as the latch pin  13  exits the concave inner cam region  68 A of the latch cam  60 A, it will have to get past the more or less rectangular corner  70 B formed by the generally flat (e.g., depicted as being horizontal in  FIG. 5A ) surface  70 A and a generally vertical inside surface  70 C of the concave inner cam region  68 A of the latch cam  60 A. Thus, the transition of the latch pin  13  out of the concave inner cam region  68 A and over the generally flat surface  70 A will have a certain “go/no go” or “discontinuous” quality to it—as opposed to a smoother, more continuous, transition quality such as that produced by the design by cam  60  of  FIG. 5  wherein the latch pin  13  slides over a generally curved surface  70 . Next it might be noted that the latch pin blocking surface (depicted as item  90  in  FIG. 7 ) has a somewhat cammed surface. In  FIG. 5A , however, it should be noted that the latch pin blocking surface  90 A is depicted as being more or less flat and vertical and thereby, in conjunction with the more or less horizontal surface  70 A, forming a substantially rectangular corner  70 D. 
         [0033]    In a somewhat similar manner, in  FIG. 7A , the return of the latch pin  13  from outside of the housing component  18 A (as generally suggested by direction arrow  91 A of  FIG. 7A ) will have a certain “go/no go” quality as the latch pin  13  moves past the abutting cam surface  90 A in order to reach a threshold level sufficient to slide past the more or less rectangular corner  70 D of the latch cam  60 A. The presence of the flat, vertical surface  90 A may be employed to hold the subject window  21 /window sash  19 /anti-tampering plate  23  in a more distinctly defined and/or visible (visible from the outside of the building) open position. It might also be noted that using a cam  60 A having the configuration generally depicted in  FIG. 5A  emphasizes the need to push in the push knob  54  (from inside the building) in order to return the latch pin  13  to the concave inner cam region  68 A of the latch cam  60 A illustrated in  FIG. 5A . 
         [0034]      FIG. 6  depicts the latch cam  60  in its second operating position wherein an outwardly directed force  56  such as that depicted in  FIG. 3  is being applied to the push rod  42  from a force  56  placed upon the push knob  54 . This force  56  is placed upon the L-shaped end  42 A of the push rod  42  and thereby causing the latch cam  60  to rotate about the axle  64  in the counterclockwise direction suggested by direction arrow  84 . This counterclockwise rotation  84  of the latch cam  60  allows the latch pin  13  to slide past the outer cammed surface  70  and on through the slot  15  (that is located in the  20 - 26  side of the housing  18 ) and the opening  11  (that is located in the  24 - 26  side of the housing) in the housing  18  and thereby allowing the window sash  19  in which the latch pin  13  is mounted to proceed to an open position such as that depicted in  FIGS. 1 and 4 . This latch cam rotation  84  also causes a top cammed surface  86  of the latch cam  60  to be forced against the cam pressure plate  78  and thereby compressing the spring  74  between the anchoring plate  76  and the cam pressure plate  78 . A continued application of the force  56  will drive the top cammed surface  86  of the latch cam  60  to its highest position which is generally depicted by level  88  of the cam pressure plate  78 . 
         [0035]      FIG. 7  shows a side cut away view of the housing  18  in which the latch cam  60  is in a third operating position wherein the outwardly directed force  56  applied to the push knob  54  has been removed. Under this condition the spring  74  (under its own expansive motive force) will return to its fully expanded position. This will cause the cam pressure plate  78  to return from its compressed spring position  88  to its extended spring position  82 . This spring expansion will cause the latch cam  60  to rotate in the clockwise direction depicted by direction arrow  85 . This, in turn, will force the push rod  42  in the inwardly directed direction suggested by direction arrow  57 . There is however an important distinction between the third operating position and the first operating position depicted in  FIG. 5 , to wit: the latch pin  13  is not nested in the inner cammed surface  68  of the latch cam  60  (as it is in  FIG. 5 ), but rather is seen abutting against an outer cam surface  90  of the right side of latch cam  60 . This latch pin  13 /outer latch pin blocking surface  90  abutting arrangement constitutes an important safety feature of this free egress latch system  10 . It serves to prevent (especially under the stress of emergency conditions such as a fire) an inadvertent relocking of the window sash  19  (i.e., return of the latch pin  13  to the inner cam region  68  as depicted in  FIG. 5 ) and thereby preventing re-access to the room wherein the window is located. In effect, the latch pin  13  abutment against latch pin blocking surface  90  of the latch cam  60  can only be overridden by again pressing the push knob  54  inward from inside the room where the push knob  54  is located. 
         [0036]      FIG. 7A  depicts the situation wherein the alternative embodiment of this invention shown in  FIG. 5A  is shown in its latch pin blocking mode. That is to say that the latch pin  13  is shown abutting against a latch pin blocking surface  90 A that is not cammed (i.e., curved) in the manner of the cammed surface  90  of  FIG. 5 , but rather flat in nature. In effect, this latch pin blocking surface  90 A presents a flat, vertical surface that is normal to the return direction line  91 A the latch cam  13  would follow if the window to which said cam  13  is attached were being forced inward (i.e., following direction line  91 A). 
         [0037]      FIG. 8  is an end view of the rectangular housing  18  as seen from side  24 - 26 . This  FIG. 8  depicts the cam plate  78  at a level  82  that comports with the extended state of the spring  74  in  FIG. 5  (and  FIG. 7 ). This figure also illustrates how the ends of the anchor plate  76  can be affixed (e.g., by welding) to the walls of the rectangular housing component  18 . Similarly, the ends of the axle  64  can be affixed to said walls of the housing component  18 .  FIG. 8  also suggests an alternative pressure plate biasing device that could take the form of a single spring  93  that could be placed in a central location  95  in the interior of the housing  18 . The respective ends of the spring  93  would reside between the anchor plate  76  and the pressure plate  78 . In effect, such a spring  93  would replace the springs  74 A and  74 B. It too would compress and decompress between opening positions  88  and  82 . In another embodiment of this invention the anchoring plate  76  can be removed and the bottom end of the single spring pressured against the inside surface  83  of the  20 - 26  side of the housing  18 . Similarly, the anchoring plate  76  could be removed and the two posts  72 A and  72 B anchored to the inside surface  83  of the  24 - 26  side of the housing  18 . 
         [0038]    Finally, it also should be appreciated that the same basic components of Applicant&#39;s free egress latch system can be used for a wide range of windows, skylights (and even doors). Moreover various field changes may be required for window, skylight or door systems of different profile or materials, and that such field changes should also to be considered to be within the scope of the claims of this patent disclosure.

Summary:
A fast operating, free egress latch system is provided with a cam having three distinct surfaces. One of these surfaces has a concave inner cam region for receiving a window latch pin. Another of these surfaces serves to prevent inadvertent relocking of a window, skylight, door, etc. once it has been opened.