Patent Document

This application is a continuation of application(s) application Ser. No. 08/574,380 filed on Dec. 18, 1995, now abandoned. 
    
    
     The present invention relates to door latches which are opened by pushing a lever on one side of a door, or pulling a lever on the opposing side of a door whereby movement of one of the levers causes a locking bolt to be withdrawn into its housing, and in particular the invention relates to the handles therefor. 
     BACKGROUND OF THE INVENTION 
     Push/pull door latches have been found particularly suitable for use on doors to hospital rooms and the like which typically open into the room. A hospital door provided with a push/pull type latch is opened from the outside by applying pressure to the push side of the latch, and opened from the inside by pulling on the pull side of the latch. A hospital technician may enter a patient&#39;s room while carrying an armload of medical equipment by merely applying pressure to the push side of the latch, thereby unlatching the door and pushing it open. Conversely, a patient who may have limited use of his or her arms because of the presence of a cast or the like, can unlatch a door and open it from the inside by pulling on the inside handle, an effort requiring a minimum of dexterity. 
     A number of push/pull type latches are available, and two typical examples can be found in Toledo, U.S. Pat. No. 5,085,474, and Walls, U.S. Pat. No. 5,403,047. 
     Push/pull door latches include a slide bolt which is movable from an extended/latched position to a retracted/release position, and a cam which is rotatable between a first position and a second position. When the cam is in the first position, a slide bolt in the door latch is in the extended/latched position. When the cam is rotated to the second position, the slide bolt is moved to the retracted/release position. The latch further includes a lever having a central fulcrum, one end of which serves as the handle, and the opposing end of which has a threaded foot added thereto by drilling and tapping that end. The foot is positioned against the cam. The handle is movable from a first position in which the cam is in its first position, and the slide bolt is extended, to a second position thereby rotating the cam to its second position, and retracting the slide bolt. 
     The handles for such push/pull type door latches are typically cast metal and require stops to prevent the rotation of the handle through a greater arc than that bounded by the first and second positions. Existing castings for handles must be drilled and machined to receive the stops. Such stops are in the form of pins and are identified by indicia number  38  in the patent to Walls, and are not shown in the patent to Toledo. A study of the specification and FIG. 1 of Toledo, however, reveals that the left handle  18  is free to rotate clockwise, and the right handle  18  is free to rotate counterclockwise unless such movement is prevented by a stop. Handles constructed in accordance with Toledo must also be drilled and machined to receive the stops. 
     To simplify the construction of such a push/pull type door latch, it would be desirable to provide a handle and a handle mounting assembly for a push/pull handle which would not require that the cast metal handle be machined to receive such stops. Specifically, it would be most desirable to provide a handle for a push/pull door latch which would not require the insertion of stops in the handle as a step towards the assembly of a door latch. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention is embodied in a push/pull latch for use on a door having a planar surface. The latch has a slide bolt which is movable from a first extended/latched position to a second retracted/release position, and a cam which is rotatable about an axis perpendicular to the surface of the door. The cam is rotatable from a first position in which the slide is in the extended/latched position to a second position in which the slide bolt is in the retracted/release position. The latch further has a first spring for urging the bolt from the second position to the first position such that the bolt is in the first position unless it is retracted by a force, such as is applied by the cam, to the second position. 
     In accordance with the present invention, a unitary base plate has a mounting portion and opposing side panels, with the mounting portion positioned against the surface of the door. The cam is mounted on a shaft perpendicular to the surface of the door and the shaft extends through the mounting portion of the base plate. To rotate the cam to the second position, a second cam is mounted on the end of the shaft which extends through the base plate, and the second cam is engaged by one end, or foot, of a lever arm. The lever arm has a central fulcrum which is pivotally mounted between the opposing panels of the unitary base plate, and the opposite end of the lever arm is a handle which is pushed or pulled to force the foot against the second cat to retract the bolt. The lever arm is movable from a first position to a second position thereby causing the foot to move the cam from its first position to its second position, and a second spring urges the lever arm from its second position, wherein the bolt is retracted, to its first position, wherein the bolt is extended. In accordance with the present invention, the lever arm is made of a unitary piece of material and includes a first stop for contacting the base plate when the lever arm is in its first position to prevent movement of the foot away from the cam when the cam is in its first position. 
     The lever arm also includes a second stop cast therein which will contact the base plate when the lever arm is in the second position to prevent further rotation of the lever after the cam has reached its second position. 
    
    
     GENERAL DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages and a better understanding of the present invention will be had by reference to the following detailed description taken in conjunction with the accompanying drawings wherein: 
     FIG. 1 is an isometric view of a portion of a door having a push/pull door latch constructed in accordance with the present invention attached thereto; 
     FIG. 2 is a cross-sectional view of the door and door latch of FIG. 1 taken through line  2 — 2  of FIG. 1; 
     FIG. 3 is a cross-sectional view of the door latch shown in FIG. 1 taken through line  3 — 3  of FIG. 2; 
     FIG. 4 is a perspective view of a cam and key assembly for use in the push/pull latch of FIG. 1; 
     FIG. 5 is a front view of the base plate on the right side of FIG.  3  and the cam for the latch shown in FIG. 1 prior to attachment of the handle thereto; 
     FIG. 6 is a front view of the base plate on the left side of FIG.  3  and the cam for the latch shown in FIG. 1; 
     FIG. 7 is an isometric view of the handle shown on the left side of the latch as seen in FIG. 3; 
     FIG. 8 is an isometric view of the handle shown on the right side of the latch as seen in FIG. 3; 
     FIG. 9 is a cross-sectional view of a second embodiment of the push/pull latch assembly of the present invention; 
     FIG. 10 is a front view of the right base plate for receiving a handle for the embodiment shown in FIG. 9; 
     FIG. 11 is a front view of the left base plate for receiving a handle for the embodiment shown in FIG. 9; 
     FIG. 12 a  is a diagramatic view of the latch of the invention shown with both latch handles extending upwardly; 
     FIG. 12 b  is a diagramatic view of the latch of the invention shown with both latch handles extending downwardly; 
     FIG. 12 c  is a diagramatic view of the latch of the invention shown with one handle extending downwardly and the opposing handle extending upwardly; 
     FIG. 12 d  is a diagramatic view of the latch shown with the latch handle extending horizontally to the left; 
     FIG. 12 e  is a diagramatic view of the latch shown with the latch handle extending horizontally to the right. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a push/pull type door latch  10  is assembled on a door  12  having a planar surface  14 . The latch includes a slide bolt  16  which is longitudinally slidable within an assembly, the outer face plate  18  of which is visible. The slide bolt  16  is depicted as being in its extended/latched position in which the distal end of the bolt  16  extends outward from the surface of the face plate  18 . When the door  12  is closed against a door frame having a strike plate, not shown, with an aperture therein to receive the extended slide bolt  16 , the door will be latched. 
     Referring to FIG. 2, the door latch  10  has cover plates  19 ,  20  positioned on each side of the door  12 . Extending from the cover plates  19 ,  20  are movable handles  22 ,  23 , respectively. The bolt  16  is retracted and the latch  10  is released by applying a push force against handle  23  or by applying a pull force against handle  22 . 
     Referring to FIGS. 2 and 3, the slide bolt assembly  24  is of the type commonly known in the art and is depicted herein with a minimum of detail. The assembly includes a tubular housing  26  which slidably receives the bolt  16  and has an angular outer end  28  which strikes the edge of a strike plate, not shown, to force the bolt  16  into the tubular housing  26 . The assembly  24  further includes a spring  30 , which urges the bolt  16  to an extended position, and a stop, not shown, which prevents movement of the bolt beyond the extended position. Centrally located within the bolt  16  is an elongate slot  32  for receiving a bolt cam  34  fitted on an elongate key  36  having a square cross section. The rear surface  38  of the slot  32  is positioned such that rotation of the crest  40  of the cam  34  against the rear surface  38  forces the bolt  16  into a retracted position in which the outer end substantially in the plane of the outer surface of the face plate  18 , as shown in phantom lines in FIG.  3 . 
     As shown in FIGS. 2,  3 ,  5  and  6 , against each of the surfaces  14  of the door  12  are base plates  42 ,  43  having planar mounting portions  44 ,  45  fitted against the surfaces  14  of the door  12 , and extending from opposing edges of the mounting portion  44  are opposing upstanding side panels  46 ,  47  and extending from opposing edges of the mounting portion  45  are opposing upstanding side panels  48 ,  49 . 
     Centrally located in the mounting portion  44  is a circular aperture  50  through which one of the distal ends of the key  36  extends. Similarly, centrally located in mounting portion  45  is a circular aperture  51  through which the opposing end of the key  36  extends. Cam assemblies  52 ,  53  are fit over one each of the distal ends of the key  36 . 
     Referring to FIG. 4, in which the key  36 , the bolt cam  34 , and the cam assemblies  52 ,  53 , are depicted, each cam assembly  52 ,  53  includes a cam  56 ,  57 , respectively, which has a square aperture  55  therein for slidably receiving the distal end of the key  36 . Each of the cams  56 ,  57  has an extension  58 ,  59 , respectively, and extending from the outward surface of each of the extensions parallel to the axis of the key  36 , are cylindrical posts  60 ,  61 , respectively, which extend from the sides of the cam member  52 ,  53 . Extending from the opposing surface of each cam member  52 ,  53  is a cylindrical sleeve, one of which  62  is visible. The sleeves  62  fit slidably within the centrally located apertures  50 ,  51  of the mounting portions  44 ,  45  of the base plate  42 ,  43  and are retained therein by retaining rings  64 ,  65  on the opposite side of each plate. 
     As can be seen, the cams  56 ,  57  are positioned on the key  36  such that the extensions,  58 ,  59  and cylindrical posts  60 ,  61  are 180 degrees apart from one another about the axis of the key  36 . Also, the crest  40  of bolt cam  34  is 90 degrees from the angular position of either post  60  or post  61 . The assembly of cams  34 ,  56  and  57 , as depicted, in FIG. 4 is in the orientation of the assembly of cams within the latch  10  while the bolt  16  is extended as shown in FIG.  1 . The rotation of the key  36  and bolt cam  34  in the clockwise direction, as viewed in FIG. 4, will force the crest  40  of cam  34  against the rear surface  38  of bolt  16  and retract the bolt  16 . The rotation of the key  36  and bolt cam  34  retract the bolt  16  and is accomplished by applying either an upward force to pin  61  or a downward force to pin  60 . 
     Referring to FIG. 5 the surface  14  of the door  12  is depicted with the base plate  42  attached thereto by a plurality of screws  66 — 66 . Cam assembly  52  is shown in solid lines in its first position with the post  60  positioned to the right of the key  36 . When the cam assembly  52  is positioned as shown in solid lines, the crest  40  of the bolt cam  34  is not against the rear surface  38  of the slot and the bolt  16  is in the extended/latched position. When the cam assembly  52  is rotated 90 degrees clockwise to the second position shown in phantom lines, the crest  40  of bolt cam  34  will rotate against the surface  38  and the slide bolt  16  will be withdrawn to the retracted/release position. 
     Referring to FIG. 6 in which the base plate  43  on the opposite side of the door  12  and the second cam assembly  53  are shown, the base plate  43  is retained by a plurality of nuts  67 — 67  tightened on the screws  66 — 66  extending from the first plate  42 . The cam  53  is depicted in solid lines with the post  61  to the right of the key  36 , and the slide bolt  16  in the extended/latched position. To retract the slide bolt  16 , the cam assembly  53  is rotated 90 degrees counterclockwise to a second position shown in phantom lines causing the crest  40  of bolt cam  34  to be forced against surface  38 . 
     Referring to FIG. 2, the left handle  23  is a push handle which can be pushed from its first position shown in solid lines in which the slide bolt is in the extended/latch position to its second position shown in phantom lines, in which the slide bolt is in the retracted/release position. Conversely, handle  22  on the right side of the door is a pull handle and may be pulled from its first position shown in solid lines in which the slide bolt  16  is in the extended/latched. position, to its second position, shown in phantom lines, in which the slide bolt  16  is in the retracted/release position. 
     Referring to FIGS. 2,  5  and  8 , the handle  22  is one end of a lever arm  68  having a centrally located transverse hole  70  through which is positioned a pivot pin  72 , the outer ends of which are fitted through apertures  74 ,  76  in the opposing side panels  46 ,  47  of the base plate  42 , and the pin  72  serves as a fulcrum about which the lever arm  68  moves. Retaining clips  78 ,  80  upon each of the distal ends of the pin  72  retain the pin  72  between the two side panels  46 ,  47 . 
     As best shown in FIGS. 2 and 8, the lever arm  68  has a hooked elongate foot  82  which is adapted to fit against the pin  60  of the cam assembly  52  and also has a stop arm  84 . The stop arm  84  is an elongate projection on the lever arm  68 , the distal end of which is adapted to abut against the outer surface of the mounting portion  44  of the base plate  42  when the lever arm  68  and handle  22  are in the first position shown in solid lines. When the handle  22  is in the first position, shown in solid lines, the arm stop  84  will prevent movement of the lower end of the handle  22  toward the door  12 . Movement of the handle  22  from the position shown in solid lines to the position shown in phantom lines in FIG. 2 will cause the foot  82  to move downwardly against the post  60  in a plane substantially normal to and spatially related to a parallel plane including the pivot pin  72  and rotate the cam assembly  52  to the second position shown in phantom lines in FIG. 2, thereby causing the slide bolt  16  to move to the retracted/release position. When the handle  22  is moved to the second position, it cannot move any farther as the cam is at the bottom of its rotation. Flange  86  provides a secure surface for mounting spring  87  to bias the lever arm  68  in its first position. 
     A spring  87  has a central portion which extends across the width of the lever arm  68  at flange  86 , and the two outer portions of the spring  87  wrap around opposite end of the pin  72 , with the distal ends thereof positioned against the surface of the mounting portion  44  of the plate  42 . The spring  87  is adapted to urge the lever arm  68  to rotate clockwise, as seen in FIG. 2, thereby urging the handle  22  from the second position shown in phantom lines to the first position shown in solid lines. 
     Referring to FIGS. 2,  6  and  7 , the handle  23  is a lever arm  88  similar to the lever arm  68  on the opposing side of the door. Like the lever arm  68 , lever arm  88  has a centrally located transverse aperture  90  through which a pin  92  is fitted and the distal ends are retained in apertures in the opposing side panels  48 ,  49  such that the pin  90  serves as the fulcrum of the lever arm  88 . The end of the lever arm  88  which is opposing to the handle  23  also has a foot  94  which engages the post  61  of the cam assembly  53  and moves the post  61  in a plane which is substantially normal to and spatially related to a parallel plane including pivot pin  92 . As best shown in FIGS. 2 and 8, the lever arm  88  includes a stop arm  95  which contacts the mounting portion  45  of the base plate  43  when the handle  23  is in the first position shown in solid lines so as to prevent further movement of the end of the handle  23  away from the door. A flange  96  on the lever arm  88  provides a secure surface for mounting the spring  98  to bias the lever arm  88  in its first position. When the handle  23  is moved to the second position shown in phantom lines, it cannot move any farther as the cam is at the top of its rotation. Spring  98  urges the lever arm  88  to rotate clockwise as seen in FIG.  2 . The lever arms  68 ,  88  which form the handles  22 ,  23 , respectively, are each made of a single unitary piece, and in the preferred embodiments are made of cast metal. When made in this fashion, the foot  82  and stop  84  of lever arm  68  and the foot  94  and stop  95  of lever arm  88  are all cast integrally with the lever arm. Therefore, the assembly is constructed with a minimum of machining. 
     A second embodiment  99  of the present invention is depicted in FIGS. 9,  10  and  11 , with part identifying numbers being generally  100  higher than like parts shown in the first embodiment. In this embodiment, the first lever arm  68  is not provided with a stop arm such as  84  in the first embodiment and, similarly, the second lever arm  188  is not provided with a stop arm such as  95  in the first embodiment. The stop arm  84  of the first lever arm  68  was intended to prevent the handle  22  from being withdrawn away from the door beyond the position shown in solid lines in FIG. 2 which would also cause the foot  82  to be withdrawn from the post  60 . In the second embodiment, the base plate  142  has a pair of opposing tabs  100 ,  102  which extend towards each other from the inner surfaces of the opposing side panels  146 ,  147 . The inner surfaces of the tabs  100 ,  102  contact an outer surface  103  of the lever arm  168  when the lever arm is in the position shown in solid lines in FIG. 9, thereby providing a stop. Similarly, a pair of inwardly extending tabs  104 ,  106  on each of the opposing side panels  144 ,  146  of the opposing base plate  143  serve as stops against an outer surface  107  of the portion of the second lever arm  188 . The outer surface  107  of the second lever arm  188  contacts the inner surface of the tab  104 ,  106  when the lever arm  188  is in the first position shown in solid lines, and thereby prevents withdrawing of the lever arm  188  and handle away from the door. 
     Referring to FIG. 12, by varying the latches and changing the positioning of the base plates on the push/pull door latch of the present invention several differing workable combinations of the assembly may be obtained. As shown in FIG. 12 a , the push/pull latch assembly may be positioned with both lever arms pointing upward. In FIG. B both lever arms may be positioned pointing downward. FIG. C discloses a push/pull type latch with one lever arm on one side of the door facing downward and the lever arm on the opposing side of the door facing upward. Likewise, one lever arm may be positioned vertically with an opposing lever arm positioned horizontally (not shown). The lever arms in FIGS. 12 a ,  12   b  and  12   c  may either be push or pull type lever arms and may be mixed, matched, or complementary depending upon the uses intended for the door. 
     Referring to FIGS. 12 d  and  12   e , in these pictures, the base plates (not shown) for the push/pull type latch have been rotated 90 degrees from that shown in FIG.  2 . In a manner similar to that shown in FIGS. 12 a  and  12   b , the latch arms may be positioned to extend either to the left as shown in FIG. 12 d  or to the right as shown in FIG. 12 e . Similarly to FIG. 12 c  it will be understood that the latch arms may also be positioned in mixed, matched, or complementary positions on the opposing side of the door. 
     After describing the first and second embodiments, it should be noted that to provide for compatibility, stop arms  84  and  95 , respectively, have been made narrow horizontally to allow the lever arms  68 ,  88  to be installed on the base plates  142 ,  143  of the second embodiment with the lever arms able to clear the inwardly extending tabs  100 ,  102 ,  104 ,  106 . 
     As can be seen, the present invention provides for the construction of a door latch assembly having stops which prevent movement of the door handle beyond the limits required for the operation of the door latch, and that the stops are manufactured without requiring machining or tooling. 
     While two embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the invention. It is, therefore, the purpose of the appended claims to cover all such changes and modifications which fall within the true spirit and scope of the present invention.

Technology Category: 0