Abstract:
A push/pull door latch assembly for use in a door includes a handle assembly and a latch cylinder. The handle assembly has a stop configured for limiting the movement of the handle during the push or pull operation, and absorbing shock transmitted from a user&#39;s hand through the handle and a cam assembly that operates in response to the push or pull operation of the handle. The cam assembly operates the latch so as to unlock the door when the handle is pushed or pulled.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to door latch assemblies, and more particularly, to push and pull door latch assemblies that are typically used in hospitals and other facilities where it is desirable to be able to unlatch and open a door in one motion by pulling or pushing a handle in the latch assembly.  
         [0002]     Push/pull type door latch assemblies are known in the art, and enable the user to easily open a door with one hand. These types of door handles enable a door to be opened inwardly into a room by pushing on an outside handle or pulling on an inside handle. Because no rotational movement is required to operate the handles, as is the case with conventional doorknobs, push/pull door latch assemblies are commonly used in hospitals and other institutions, and can be easily used in an emergency by the disabled or by young children.  
         [0003]     In current applications, a pull handle of a door latch assembly is mounted on the side of the door toward which the door opens and a push handle of the door latch assembly is mounted on the opposite side thereof. These assemblies typically incorporate a cam which causes the pushing or pulling movement of the handle to rotate an elongate key extending perpendicularly through an opening in a latch cylinder. When rotated, the elongate key withdraws the door latch to release the door. Generally, only a small amount of force in one direction is sufficient to release the latch.  
         [0004]     However, because of the generally high-traffic, high-pressure atmosphere in hospitals and the like, both the cam and the handle can become worn down and damaged due to repeated use of the assembly. Every time the door latch assembly is operated, the cam experiences a shock due to the pushing or pulling of the handle, which wears down the cam, particularly when the shock is excessive, as can happen in emergency situations. As either the cam or the handle become worn down, it can become more difficult for a user to push or pull on the door handle, which can lead to dangerous consequences in an emergency situation. These instances reduce the life of the apparatus and require replacement.  
         [0005]     Therefore, there exists a need to better protect latch assemblies from the shock experienced during operation of the push/pull door latch assembly, thereby increasing the life of the assembly. There also exists a need to reduce the wear on the latch assembly, so that the ease of operating the push/pull handle remains consistent and reliable despite repeated use.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     The above-listed objects are met or exceeded by the present push/pull door latch assembly, which features a stop that is configured to reduce the shock experienced by the cam during operation of the door assembly. The stop reduces the wear on both the cam and the handle, increasing the life of the door latch assembly.  
         [0007]     More specifically, the present invention provides a push/pull door latch assembly for use in a door, including a handle assembly and a latch cylinder, the latch cylinder including a latch, and the handle assembly including a mounting plate having a pair of sidewalls, a handle secured between the sidewalls for a push or pull operation, a stop configured for limiting the movement of the handle during the push or pull operation, and a cam assembly operating in response to the push or pull operation of the handle, the cam assembly operating the latch so as to unlock the door when the handle is pushed or pulled. 
     
    
     DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0008]      FIG. 1  is a perspective view of one embodiment of the present push/pull door latch assembly as it appears in a door;  
         [0009]      FIG. 2  is a fragmentary side view of the assembly of  FIG. 1 ;  
         [0010]      FIG. 3  is an exploded perspective view of  FIG. 1 ;  
         [0011]      FIG. 4  is a front view of the cam assembly as it appears on the mounting plate of the assembly of  FIG. 1 ;  
         [0012]      FIG. 5  is a side view of the stop of the assembly of  FIG. 1 ; and  
         [0013]      FIG. 6  is a top view of the stop of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Referring to  FIGS. 1 and 3 , the present push/pull door latch assembly is shown and generally designated  10 . The assembly  10  generally includes a latch cylinder  11  and a handle assembly  12 . The latch cylinder  11  includes a latch  14 , and the handle assembly  12  includes a mounting plate  16  having a pair of sidewalls  18 , a handle  20  secured between the sidewalls for a push or pull operation, a stop  22  configured for limiting the movement of the handle during the push or pull operation, and a cam assembly  24  operating in response to the push or pull operation, the cam assembly operating the latch so as to unlock the door when the handle is pushed or pulled.  
         [0015]     As is generally known in the art, the assembly  10  is mounted to a door  26 , and is configured for engaging the latch  14 , which facilitates opening and closing of the door. As is also known in the art, the assembly  10  is generally covered by a faceplate  28  that is secured to the sidewalls  18  by at least one pair of faceplate screws  30 . The faceplate  28  is preferably manufactured from stainless steel, although it is appreciated that other materials with similar properties are available, as are known in the art.  
         [0016]     The use of the faceplate screws  30  enable easy assembly and disassembly of the faceplate  28  to and from the mounting plate  16 . However, other means of attachment are available, such as a snap-fit or tongue-and-groove fit, as are known in the art.  
         [0017]     The faceplate  28  includes a generally rectangular shaped opening  31  that is configured for receiving the handle  20 , although it is appreciated that other shapes are available. The handle  20  is configured to be either a push or pull handle, depending on which side of the door  26  the assembly  10  is located and also on the needs of the application. The handle  20  is preferably manufactured by investment casting stainless steel, as is known in the art. However, other materials and methods of manufacture are also available.  
         [0018]     Referring to  FIGS. 3 and 4 , the mounting plate  16  includes a generally rectangular centrally located opening  32  configured for alignment with a generally circular opening  33  in the door  26 . The latch cylinder  11  is secured within the door opening  33 , and has an opening  34  configured for general alignment with the mounting plate opening  32 . In the present embodiment, the mounting plate  16  is manufactured from stainless steel, although it is appreciated that other similar materials are available, as are known in the art.  
         [0019]     As is known in the art, a lock mortise  36  is installed in an opening in an edge  37  of the door  26  through which the latch  14  of the latch cylinder  11  protrudes to latch the door in a door jamb (not shown).  
         [0020]     As seen in  FIG. 3 , each of the sidewalls  18  includes at least one pair of laterally aligned openings  38 . In the present assembly  10 , there are two pairs of laterally aligned openings  38   a  and  38   b.  In this embodiment, one pair of the openings  38   a  is configured for receiving a shaft  39 , and the other pair of openings  38   b  is configured for receiving a pivot pin  40 . However, it is appreciated that other arrangements and quantities of laterally aligned openings are available, depending on the needs of the application.  
         [0021]     Referring to  FIG. 3 , the handle  20  is disposed between the sidewalls  18  by means of the pivot pin  40 . In the present embodiment, the pivot pin  40  is manufactured from 6061-T6 Aluminum, as is known in the art. However, other materials with similar properties are available.  
         [0022]     The pivot pin  40  allows for proper operation of the handle  20 , and maintains alignment of the handle within the assembly  10 . A torsion spring  42  is located on the pivot pin  40 , and is configured for returning the handle  20  to its no-load or starting position when the handle is released, as is known in the art. The torsion spring  42  is generally U-shaped, with coiled spring-shaped side portions  44   a,    44   b,  a horizontal bottom portion  46  and a pair of legs  47 .  
         [0023]     Each of the spring-shaped side portions  44   a,    44   b  is configured for wrapping around the pivot pin  40 , on opposite sides of the handle  20 , respectively (see  FIG. 3 ). The bottom portion  46  is located underneath and generally abuts a generally planar section  48  of the handle  20 .  
         [0024]     Each of the legs  47  lies parallel to a longitudinal axis of the mounting plate  16  and is configured to abut against a top side  49  of the mounting plate, adjacent to the sidewalls  18  ( FIG. 2 ). In the present assembly  10 , the torsion spring  42  is manufactured from stainless steel. However, it is appreciated that other materials with similar properties are available, as are known in the art.  
         [0025]     Referring to  FIGS. 2, 3  and  5 , the stop  22  includes a through-hole  50  configured to loosely receive the shaft  39 . Preferably both the stop  22  and the shaft  39  are manufactured by investment casting stainless steel, or any other suitable method and material, as are known in the art. The stop  22  has a backside  52  configured for parallel arrangement with one of the sidewalls  18 .  
         [0026]     In the present embodiment, the backside  52  is not rigidly fixed or abutted against the sidewall  18 . Rather, the stop  22  is loosely held between the sidewall  18  and the handle  20 . A top  53  of the stop  22  is configured to exceed the height of the generally planar section  48  of the handle  20  in its starting position ( FIG. 2 ). The stop  22  remains between the sidewall  18  and the handle  20  because of the higher clearance of the top  53 . This arrangement prevents the stop  22  from moving underneath the generally planar section  48  and interfering with the operation of the handle  20 .  
         [0027]     The stop  22  further includes a bottom surface  54  having a first part  56  and a second part  58 . The first and second parts  56 ,  58  are not parallel with the longitudinal axis of the mounting plate  16 , but are instead disposed at angles relative to the longitudinal axis of the mounting plate. The angles can be measured from an apex  60 , which is in contact with the mounting plate  16 .  
         [0028]     Referring to  FIG. 5 , in the present embodiment, the first part  56  is disposed at an angle a with respect to the longitudinal axis of the mounting plate  16 . It is preferred that the angle a be approximately 10°, though other angle measurements are possible. The second part  58  is disposed at an angle β with respect to the longitudinal axis of the mounting plate  16 . In the present embodiment, the angle β has a measurement of approximately 5°, although other measurements are available.  
         [0029]     The angular configurations of the first part  56  and the second part  58  of the stop  22  ( FIG. 5 ) aid in reducing the shock experienced by the handle  20 , because the stop is not rigidly fixed on the shaft  39  and can toggle somewhat. It is contemplated that the toggling movement of the stop  22  reduces the shock on the handle  20  because unlike a rigidly fixed stop, which abruptly stops movement, the current stop will move with the handle and gradually stop its movement. It is also believed that this arrangement helps to increase the life of the handle.  
         [0030]     As is seen in  FIGS. 2 and 3 , the stop  22  further includes a notch  61  configured for receiving one of the pair of legs  47  of the torsion spring  42  and a ledge  62  that extends outward from a front side  64  of the stop  22 .  
         [0031]     The generally planar section  48  of the handle  20  is configured for engaging the ledge  62  in operation. During handle operation, the handle  20  is either pushed or pulled, depending on the needs of the application. The generally planar section  48  of the handle  20  engages the ledge  62  of the stop  22 , limiting the movement of the handle. By limiting the movement of the handle  20  during operation, the velocity at which the handle travels is also limited, which reduces the shock experienced by the handle.  
         [0032]     Because the shock on the handle  20  is decreased in comparison to current assemblies, the wear on the handle is also reduced, and as a result, it is contemplated that the life of the handle and the assembly as a whole is increased.  
         [0033]     Referring to  FIGS. 3 and 4 , the cam assembly  24  is preferably disposed on an underside  66  of the mounting plate  16 , and is preferably aligned with the mounting plate opening  32 . This arrangement allows the handle  20  to engage the cam assembly  24  during operation, which will be described in further detail below.  
         [0034]     As is best seen in  FIG. 3 , the cam assembly  24  includes a cam  68 , as is known in the art. The cam  68  is preferably manufactured from cold-rolled stainless steel, although it is appreciated that other materials and methods of manufacture are available. It is contemplated that the stainless steel cam  68  will absorb shock and last longer than cams that are manufactured from bronze or other relatively softer materials.  
         [0035]     The cam assembly  24  further includes a screw plate  70  having a generally rectangular-shaped protruding section  71  configured for being received by the mounting plate opening  32 . The protruding section  71  includes a generally centrally located opening  72  that is configured for alignment with the mounting plate opening  32  and the latch cylinder opening  34 . The screw plate  70  is preferably manufactured by investment casting stainless steel or the like.  
         [0036]     The cam  68  is pivotally attached within the centrally located opening  72  by a pivot pin rod  73 , and is configured for engagement by the generally planar section  48  of the handle  20  during operation. The screw plate  70  is attached to the underside  66  of the mounting plate  16  by at least one pair of screw plate screws  74 , each of which is located in a respective sunken portion  76  of the screw plate in an underside  78  of the screw plate ( FIG. 2 ).  
         [0037]     During operation of the assembly  10 , the handle  20  is either pushed or pulled, depending on the needs of the application. When the handle  20  is in operation, the generally planar section  48  of the handle engages the cam  68 , causing an elongate key  80  of the cam to enter the latch cylinder opening  34 , engaging the latch  14  and moving it so that the door  26  can be opened.  
         [0038]     When the generally planar section  48  engages the cam  68 , it also engages the ledge  62  of the stop  22 . It is contemplated that the ledge  62  limits the movement of the handle  20 , reduces the shock experienced by the handle, and only permits the minimal amount of force necessary to engage the elongate key  80  of the cam  68  against the latch  14  of the latch cylinder  11 . It is further contemplated that the angular arrangement of the first part  56  and the second part  58  of the stop  22  also aids in reducing shock on the handle  20  because of the toggling movement of the stop, described above.  
         [0039]     The constant use of push/pull door assemblies in hospitals and other high-traffic areas generally cause the cam  68  to become worn down after repeated use. However, as described above, it is contemplated that in the present assembly  10 , the wear on the cam  68  is reduced, thereby increasing its life.  
         [0040]     While a particular embodiment of the low profile push/pull door latch apparatus has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.