Abstract:
A latch is provided for a mortise lock of the type comprising a housing for accommodating the lock components. The latch comprises a first and second portions movably mounted in the housing and a securing element for releasably connecting the first and second portions in either a first relative axial position or a second relative axial position where the first and second portions of the latch are rotatable relative to one another. In the first axially connected position of the latch, the first and second portions of the latch are movable together relative to the housing so that the first portion at least partially non-rotatably projects outwardly from the opening in the housing in an extended position of the latch, and the first portion is inside the housing in a retracted position of the latch. In the second axially connected position of the latch, the first portion of the latch extends further outwardly from the opening in the housing so that the first portion is rotatable relative to the housing and the first portion may be rotated to a selected position and returned to the first axially connected position of the first and second portions of the latch.

Description:
BACKGROUND OF INVENTION  
         [0001]    This invention relates generally to door latch assemblies, and more particularly to a reversible latch bolt for use with latch assemblies in mortise locks so that the mortise lock can be used with both right-hand and left-hand doors.  
           [0002]    A mortise lock fits into a mortised recess formed in the edge of a door which is opposite to the edge of the door that is hinged to the door frame. The mortise lock generally includes a rectangular housing, or case, which encloses the lock components. The principal lock component is a beveled latch bolt which projects beyond the edge of the door and into an opening or strike plate in the door frame to latch the door in a closed position. The latch bolt is moveable to a retracted position inside the case to permit opening of the door by operation of a latch operator, such as a door knob or lever handle.  
           [0003]    Adjustments must be made to the mortise lock depending on whether the lock is mounted in a left-hand or right-hand door. A mortise lock mounted in a left-hand door must be rotated 180° about a vertical axis for mounting in a right-hand door. Consequently, the latch bolt must also be rotated 180° about a horizontal axis so that the beveled face of the latch bolt faces the door-closing direction.  
           [0004]    Ideally, the necessary adjustments to the mortise lock can be accomplished without opening the case. Typically, the latch bolt can be pulled partially out of the housing, usually against the force of a spring, rotated 180° and then allowed to be pulled back into the housing by the spring. However, this arrangement can lead to tampering after the lock is installed since the latch bolt can be reversed even when the mortise lock is in the door, which would prevent the door from the closing. Moreover, the conventional mechanisms for reversing the operation of the locking mechanism are complicated and difficult to manipulate.  
           [0005]    For the foregoing reasons, there is a need for a latch assembly for use in a reversible mortise lock which includes a latch bolt that cannot be reversed after the lock is installed in a door. Reversal of the latch bolt for use with a door of the opposite hand should be easily accomplished in the field. The new latch assembly should be straightforward to manufacture and use.  
         SUMMARY OF INVENTION  
         [0006]    According to the present invention, a latch is provided for a mortise lock of the type comprising a housing for accommodating the lock components including the latch and having at least one opening. The latch comprises a first portion and a second portion adapted to be movably mounted in the housing and a securing element for releasably connecting the first portion and the second portion in either a first relative axial position or a second relative axial position where the first and second portions of the latch are rotatable relative to one another. In the first axially connected position of the latch, the first and second portions of the latch are movable together relative to the housing so that the first portion at least partially non-projects outwardly from the opening in the housing in an extended position of the latch, and the first portion is inside the housing in a retracted position of the latch. In the second axially connected position of the latch, the first portion of the latch extends further outwardly from the opening in the housing so that the first portion is rotatable relative to the housing and the first portion may be rotated to a selected position and returned to the first axially connected position of the first and second portions of the latch.  
           [0007]    Also according to the present invention, a mortise lock is provided comprising a housing including two principal side walls and edge walls extending between and interconnecting the side walls. One of the side walls and one of the edge walls of the housing each having at least one opening. A latch bolt is mounted in the housing for movement with respect to the housing. The latch bolt includes a head portion, a rod portion, and a securing element for releasably connecting the head portion and the rod portion in either a first relative axial position or a second relative axial position where the head and rod portions of the latch bolt are rotatable relative to one another. In the first axially connected position, the head and rod portions of the latch bolt are movable relative to the housing so that the head portion at least partially non-rotatably projects outwardly from the opening in the edge wall of the housing in an extended position of the latch bolt and the head portion is inside the housing in a retracted position of the latch bolt. In the second axially connected position, the head portion of the latch bolt extends further outwardly from the opening in the edge wall of the housing so that the head portion is rotatable relative to the housing and the head portion may be rotated to a selected position and returned to the first axially connected position of the head and rod portions of the latch bolt. Means are provided for biasing the latch bolt outwardly of the housing. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]    For a more complete understanding of the present invention, reference should now be had to the embodiments shown in the accompanying drawings and described below:  
         [0009]    [0009]FIG. 1 is a partially exploded perspective view of an embodiment of a mortise lock assembly according to the present invention;  
         [0010]    [0010]FIG. 2 is a side elevation view of the mortise lock assembly of FIG. 1 with a side wall removed;  
         [0011]    [0011]FIG. 3 is an exploded perspective view of an embodiment of a latch assembly according to the present and used in the mortise lock assembly of FIG. 1;  
         [0012]    [0012]FIG. 4 is a longitudinal sectional view of the latch assembly of FIG. 3 in the mortise lock; and  
         [0013]    [0013]FIGS. 5-7 are longitudinal sectional views of a method for reversal of the latch bolt according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0014]    Certain terminology is used herein for convenience only and is not to be taken as a limitation on the invention. For example, words such as “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configuration shown in the FIGs. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise.  
         [0015]    The latch bolt assembly according to the present invention is for use in a mortise lock and may be used with any conventional mortise lock such as, for example, the mortise locks described by U.S. Pat. Nos. 4,118,056; 5,678,870; 6,349,982 and 6,393,878, the contents of all which are hereby incorporated by reference. Accordingly, detailed explanations of the functioning of all of the mortise lock components are deemed unnecessary for an understanding of the present invention by one of ordinary skill in the art.  
         [0016]    Referring now to FIG. 1, an embodiment of a mortise lock according to the present invention is shown and is generally designated by reference numeral  20 . The lock  20  comprises a generally rectangular box, or case  22 , for housing the lock components and is adapted to be received in a mortise in the free, or unhinged, edge of a door (not shown). One of the side walls of the case  22  comprises a cap  24  which is secured to and forms a closure for the case  22 .  
         [0017]    [0017]FIG. 2 shows the mortise lock  20  with the cap side wall  24  removed. The case  22  includes a side wall  26  and integral top  28 , bottom  30 , front  32  and rear  34  walls. As seen in FIG. 1, the front wall  32  has a latch bolt opening  36 , a deadbolt opening  38 , an auxiliary bolt opening  40  and an opening  42  for a flush-mounted toggle. A face plate  44  is secured with screws  46  to the front wall  32  of the case  22  and has an opening  48  for the latch bolt corresponding to the latch bolt opening  36  in the case  22 . It is understood that other openings can be provided in the face plate  44  which correspond to the openings in the front wall  42  when the associated lock components are present.  
         [0018]    An embodiment of the latch assembly according to the present invention is shown in FIG. 3 and designated generally at  50 . The latch assembly  50  comprises a latch bolt including a bolt head  54  and a latch tail  56 , an anti-friction lever  58 , a coil spring  60 , spring washers  62 , a guide block  64  and a spring clip  66 . The bolt head  54  includes a beveled face  68  and a slot  70 . A pin  72  extends through a hole  74  in the bolt head  54 , into the slot  70  and a hole in the anti-friction lever  58  for pivotally mounting the anti-friction lever to the bolt head  54 . An arm  76  extends from one side of the anti-friction lever and transversely from the beveled face  68  of the bolt head  54 . When the latch assembly  50  is in the case (FIGS. 2 and 4), the arm  76  engages behind the face plate  44 . The inner end  78  of the bolt head  54  is generally cylindrical and has an axial bore  79  (not seen in FIG. 3) for receiving the outer end of the latch tail  56 .  
         [0019]    The latch tail  56  has a cylindrical body and a circumferential groove  80  adjacent the outer end of the latch tail  56 . The body of the latch tail  56  tapers inwardly beginning at a point spaced longitudinally outwardly from the groove  80 . The tapered portion  82  of the latch tail  56  terminates at the outer end of the latch tail  56  forming a disc-like outer end  83  to the latch tail  56 . A tail plate  84  is fixed to the inner end of the latch tail  56  transversely to the axis of the latch tail  56 .  
         [0020]    The guide block  64  is generally cube-shaped and has a pass-through opening  86  for slidably receiving the latch tail  56 . The sides of the base  88  of the guide block  64  are flat and slide against the side walls  24 ,  26  of the case  22  for supporting linear movement of the latch tail  56 . The front surface of the base  88  of the guide block  64  serves as a retraction surface  89 .  
         [0021]    The spring clip  66  is an L-shaped piece, the longer leg  94  of the spring clip defining a circular opening  96 . The inner end  78  of the bolt head  54  has a transverse slot  92  for receiving the spring clip  66  and which intersects the axial latch tail bore  79 . Two coil springs  98  are disposed in depressions  100  in a transverse channel  102  in the inner end of the bolt head  78 .  
         [0022]    In FIGS. 2 and 4, the latch bolt is shown in an extended position in the mortise lock  20  with the bolt head  54  partially projecting from the opening  36  in the front wall  32  and face plate  44 . The latch tail  56  extends rearwardly from the bolt head  54  through a guide slot formed in a boss  104  fixedly mounted between the side walls  24 ,  26  for guiding and supporting the linear reciprocal movement of the latch bolt. The spring clip  66  is disposed in the slot  92  in the bolt head  54  such that the opening  96  in the spring clip  66  aligns with the axial bore  79  in the bolt head  54 . The springs  98  under the shorter leg  95  of the spring clip  66  bias the spring clip  66  away from the bolt head  54 . As shown in FIG. 4, the edge of the spring clip opening  96  fits into the groove  80  in the latch tail  56 . The bolt head  54  and latch tail  56  are thus secured to move together during normal operation of the mortise lock  20 . The coil spring  60  is held in compression between the bolt head  54  and the boss  104  for biasing the latch bolt outwardly to the extended position.  
         [0023]    As is conventional, the latch bolt is moveable in the openings in the front wall  32  of the case  22  and face plate  44  to the retracted position inside the case  22  by operation of a latch operator comprising either an inside or outside knob or lever handle or a cylinder lock (not shown). In the embodiment shown, retracting means comprises at least one rollback hub  120  rotatably mounted in the case  22  below the latch assembly  50  (FIG. 2). The hub  120  includes a square aperture  122  for non-rotatable connection to a spindle drive (not shown) connected to the knobs or lever handles for rotating the hub  120 . The hub  120  has an upwardly extending leg  124 . The upper portion of the leg  124  has a rearwardly facing bearing surface  130  for engaging the front retraction surface  89  of the guide block  64 . The latch bolt is retracted by rotating the hub  120  in a clockwise direction, as seen in FIG. 2. Rotation of the hub  120  causes the bearing surface  130  to engage the retraction surface  89  of the guide block  64  to move the latch bolt linearly inward to the retracted position. A spring arm  126  is mounted transversely in the rear wall  34  of the case  22 . A coil spring  128  fits around the arm  126  and acts between the rear wall  34  and the hub  120  to urge the hub  120  toward engagement with the boss  104  for restoring the hub  120  to the neutral or home position, shown in FIG. 2, when the latch operator is released. It is understood that the mortise lock assembly may have independent hubs to which inside and outside spindle drives are connected, respectively.  
         [0024]    In addition, the latch bolt automatically retracts when the anti-friction lever  58  and the beveled face  68  of the bolt head  54  engage the door frame or strike upon closing of the door. Initially, the anti-friction lever  58  engages the door frame pivoting the anti-friction lever on the pin  72  in the bolt head  54 . As the anti-friction lever  58  pivots, the arm  76  works against the inner surface of the face plate  44  driving the latch bolt  52  rearward into the case  22 . When the latch operator is released, or the door is in the door frame, the coil spring  60  returns the latch bolt to the extended position.  
         [0025]    According to the present invention, the latch bolt is reversible for use with a door of the opposite hand. In order to reverse the latch bolt, it is necessary to disconnect the bolt head  54  from the latch tail  56 , rotate the bolt head  54  relative to the latch tail  56  and the lock case  22 , and reconnect the bolt head  54  to the latch tail  56 . This operation is shown in FIGS. 1 and 5- 7 .  
         [0026]    The first step is to remove the face plate  44 , as seen in FIG. 1. Next, the spring clip  66  is manually depressed by inserting a tool, such as a screw driver  108 , through an opening  106  in the cap side wall  24 . As seen in FIG. 5, pressing on the spring clip  66  with a screw driver  108  pushes the spring clip  66  downwardly against the force of the springs  98  thereby aligning the opening  96  in the spring clip  66  and the axial bore  79  in the bolt head  54  freeing the latch tail  56  from the spring clip  66  for movement relative to the bolt head  54 . The bolt head  54  is then biased by the spring  60  outwardly of the case  22  through the opening  36  in the front wall  32  (FIGS. 1 and 6). As bolt head  54  moves outward of the case  22 , the flange  95  on the spring clip  66  moves out from under the tip of the screwdriver  108 . This allows the spring clip  66  to snap outward of the bolt head  54  under the force of the springs  98 . As the bolt head  54  continues to move outward, the spring clip  66  advances along the tapered portion  82  of the latch tail  56  until the spring clip engages behind the disc-like outer end  83  of the latch tail  56 . In this position, only the inner cylindrical portion  78  of the bolt head  54  remains in the case  22  so that the bolt head  54  is free to rotate on the latch tail  56 .  
         [0027]    The bolt head  54  is rotated 180° (FIGS. 1 and 6) and pushed back into the case  22 . FIG. 7 shows the bolt head  54  during reinsertion into the case  22  along the latch tail  56 . Since the outer end of the latch tail  56  is already in the axial bore  79  in the bolt head  54 , reinsertion of the bolt head  54  is guided by the latch tail  56 . As the bolt head  54  moves into the case  22  along the latch tail  56 , the edge of the opening  96  in the spring clip  66  engages and advances along the tapered portion  82  of the latch tail  56  forcing the spring clip  66  into the  92  (as seen in FIG. 7) against the force of the springs  98 . The bolt head  54  is advanced into the case  22  until the relative position of the bolt head  54  and latch tail  56  is such that the spring clip  66  is again received in the circumferential groove  80  in the latch tail  56  securing the bolt head  54  and latch tail  56 . The face plate  44  is replaced such that the arm  76  on the anti-friction latch  58  is behind the face plate  44 . It is understood that the spring clip  66  is now accessible through an opening  106  in the cap side wall  26  in the event that the user desires to reverse the described process and return the bolt head  54  to the prior position.  
         [0028]    It is understood that the embodiments of the inner portion  78  of the bolt head  54  and the spring clip  66  are exemplary and other structures are possible, as long as such other structures releasably hold the bolt head  54  and latch tail  56  for movement together and, when released, allows the bolt head  54  to move axially relative to the latch tail  56  and rotatably relative to the case  22  without disconnection from the latch tail  56 . Other means for biasing the spring clip  66  to the position where the spring clip  66  partially blocks the axial bore  79  in the bolt head  54  are possible. For example, an alternative embodiment of the spring clip  66  for use in the latch assembly  50  of the present invention would replace the short leg of the L-shaped spring clip  66  with an angled tab extending from one edge of the clip. The spring clip tab would work against the surface of the inner end  78  of the bolt head  54 . This embodiment of the spring clip  66  could function without the coil springs  98  if the material of the spring clip  66  was flexible enough to allow the clip to be pushed down to clear the bolt head bore  79 . Thus, we do not intend to limit ourselves to the specific embodiments of the bolt head and spring clip, or the spring clip biasing means, shown herein.  
         [0029]    The previously described embodiments of the present invention have many advantages, including the provision of a reversible mortise lock which cannot be tampered with after installation. The releasing mechanism of the latch assembly is only accessible through the side walls of the mortise lock case. Therefore, latch bolt reversal must be performed before the lock is installed in the door. Moreover, the latch bolt reversal does not require removal of the entire latch bolt from the case. The mortise lock incorporating the new latch assembly is easily modified for use with either a right-hand door or a left-hand door from outside of the lock casing with a screw driver. The latch assembly is simple to reverse in the field prior to installation in the door.  
         [0030]    Although the present invention has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the invention to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. For example, several means are possible for releasably securing the latch tail to the bolt head. Accordingly, we intend to cover all such modifications, omission, additions and equivalents as may be included within the spirit and scope of the invention as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.