Patent Abstract:
A latch assembly having a latch housing and handle that are substantially or near flush with the surrounding outer surface of the door in which they are mounted when the latch assembly is in its closed position. The latch assembly utilizes a locking cylinder as a push-button mechanism in order to release at least a portion of the handle, which then pivots to an extended position where it can be grasped and turned by an operator. A spindle and latching pawl are slidably connected to the handle and bound by a camming surface in the latch housing so that the spindle and latching pawl moves both axially and rotationally at the same time so that, upon closing, the pawl will cinch down on the frame to create a tight closure between the door and frame.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    None.  
         BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to latches that are flush or near flush when mounted in a door or frame. Typically, the latch handle is contained with this low profile while not in use, but may be extended in some way to provide access to an operator. Once extended, the handle may be operated to open the door.  
           [0003]    One example of such a generally flush mounted latch assembly is U.S. Pat. No. 5,450,735, issued to Takanobu Esaki, et al. of Tokyo, Japan on Sep. 19, 1995. Esaki discloses a pull-out-and-rotate type latch assembly. When locked, the latch handle lies nearly flush with the surrounding housing and door. When unlocked, the handle may be pivoted to an extended position and turned thereby turning a latching plate at the end of a spindle, allowing the door to be opened. Another example of a flush type latch assembly is U.S. Pat. No. 5,457,971, issued to Kenichi Yamada of Tokyo, Japan on Oct. 17, 1995. Yamada discloses a push-button spring-loaded rotary type latch assembly in which a torsion spring urges the handle into an extended position when a push-button is depressed.  
           [0004]    In both Esaki and Yamada, the key cylinder is mounted in the handle and the shaft and latching plate can only rotate. Since the key cylinder is mounted in the handle, the length of the handle is dictated in part by how many fingers must fit between the key cylinder and the handle&#39;s pivot. Since the latching plate in each does not move axially but only rotates, it does not additionally cinch the door to the frame upon closing. Also, a separate push button mechanism is utilized to release the handle.  
           [0005]    What is needed is a push-button type flush mounted latch assembly wherein the push button mechanism is greatly simplified. Additionally, what is needed is such a latch in which the key cylinder may work just as well if mounted in the housing rather than the handle. What is further needed is a latch assembly that causes the latching pawl to both rotate and draw in upon closing so that the door is cinched tightly to the frame.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    An object of the present invention is to provide a door latch assembly having a latch housing and handle that are substantially or near flush with the surrounding outer surface of the door in which they are mounted when the latch assembly is in its closed position.  
           [0007]    A further object of the present invention is to provide such a latch assembly that utilizes a push-button mechanism in order to release at least a portion of the handle to be pivoted to an extended position and grasped and turned by an operator. Another object of the present invention is to provide such a flush mounted latch in which the push button unit comprises a greatly simplified configuration. Another object of the present invention is to provide such a flush mounted latch in which the locking cylinder itself may operate as the push button for releasing the handle.  
           [0008]    It is a further object of the present invention to provide a locking shaft that is slidably connected to the handle so that the locking shaft may move axially as well as rotate at the same time so that a pawl member on the end of the locking shaft may cinch down on the frame to create a tight closure between the door and frame.  
           [0009]    These objects are accomplished by the present invention of a latch assembly having a latch housing and handle that are substantially or near flush with the surrounding outer surface of the door in which they are mounted when the latch assembly is in its closed position. The latch assembly utilizes a greatly simplified push-button mechanism in order to release at least a portion of the handle, which then pivots to an extended position and grasped and turned by an operator. A spindle and latching pawl are slidably connected to the handle and bound by a camming surface in the latch housing so that the spindle and latching pawl moves both axially and rotationally at the same time so that, upon closing, the pawl will cinch down on the frame to create a tight closure between the door and frame.  
           [0010]    Other aspects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed descriptions of preferred embodiments when considered in conjunction with accompanying drawings, which illustrate, by way of example, the principles of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of one embodiment of the present invention.  
         [0012]    [0012]FIG. 2 is a top view of one embodiment of the present invention.  
         [0013]    [0013]FIG. 3 is an exploded view of the embodiment of FIG. 1.  
         [0014]    [0014]FIG. 4 is a perspective view of a camming surface of one embodiment of the present invention.  
         [0015]    [0015]FIG. 5 is a side elevation view of the camming surface of FIG. 4.  
         [0016]    [0016]FIG. 6 is a top plan view of the camming surface of FIG. 4.  
         [0017]    [0017]FIG. 7 is a perspective view of a push button unit of one embodiment of the present invention showing two retention members in which one retention member is partially depressed.  
         [0018]    [0018]FIG. 8 is a top plan view of the push button unit of FIG. 7 in which no retention members are depressed.  
         [0019]    [0019]FIG. 9 is a cross-section view taken along the line  9 - 9  in FIG. 8 showing a depressible retention member not depressed.  
         [0020]    [0020]FIG. 10 is a cross-section view of a portion of the handle of one embodiment as shown in FIG. 2 taken along the line  10 - 10  in FIG. 2 showing an engagement surface having a ridge  65 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    The detailed description set forth below in connection with the appended drawings is intended as a description of presently-preferred embodiments of the invention and is not intended to represent the only forms in which the present invention may be constructed and/or utilized. The description sets forth the functions and the sequence of steps for constructing and operating the invention in connection with the illustrated embodiments. However, it is to be understood that the same or equivalent functions and sequences may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention.  
         [0022]    Referring now to the drawings, FIGS. 1 and 2 show one embodiment of the present invention. In particular, this embodiment involves a low profile latch  10 , either flush or near flush with the surrounding top surface of the door or panel (not shown) in which the latch  10  is mounted. The latch  10  is comprised of a latch housing  15 , handle  60 , and locking shaft or spindle  50 .  
         [0023]    The shaft or spindle  50  would ordinarily have a pawl member  90  mounted to it by any number of standard means. The effect would be that rotation of the shaft  50  would rotate the pawl  90  into a position to cause closure between the door and a mating surface on the surrounding frame or alternatively into a position behind the door so that the door may be opened relative to the surrounding frame. Similarly, axial movement of the shaft  50  causes the pawl  90  to move in the axial direction so that when the shaft  50  is drawn upward toward the latch housing  15 , the pawl  90  cinches down on the mating surface of the surrounding frame and create a tight seal between the door and the frame. Additionally, the application may or may not involve a gasket (not shown) between the door and frame. Either way, the rotary and axial movements of the locking shaft  50  are translated to the pawl  90  which is mounted on or fixed to the shaft  50 .  
         [0024]    [0024]FIG. 3 illustrates an exploded view of an embodiment of the present invention showing a latch housing  15  comprising a first chamber  20  and a second chamber  30  and a generally longitudinal recess  14  intermediate the two chambers. A plug or retainer unit  40  is rotatably housed in the first chamber  20 . On its upper end, the retainer unit  40  has a whole that retains handle pivot  62 . On its lower end, the retainer unit  40  has a pair of slots  44  that slidably house follower members  24 .  
         [0025]    Handle  60  is mounted on pivot  62  and can pivot between a closed and extended position. Torsion spring  66  is positioned between the retainer unit  40  and the handle  60  urging handle  60  toward the extended position. In FIG. 3, the torsion spring  66  is wrapped around pivot  62  of the handle  60 , but the handle  60  could be urged toward the extended position by any number of other means, including a compression spring anchored on one end in or by the upper surface of the retainer unit  40 , the other end imposing its compressive force on the lower surface of handle  60 . Other biasing methods well known in the art may be employed to bias the handle in the extended direction without going beyond the intent of the present invention.  
         [0026]    When in the closed position, at least in part of handle  60  rests inside the longitudinal recess  14  of latch housing  15 , and is held in place by a push button unit  80 . In the embodiment shown in FIG. 3, the surface of push button unit  80  has one or more handle retention members  84  which engage with one or more engagement surfaces  64  of handle  60  to hold handle  60  in the closed position against the urging of biasing means  66 . Push button unit  80  is urged upward by a compression spring  36 . The force of compression spring  36  may be easily overcome, however, by the operator who presses downward on the top surface of the push button unit  80 .  
         [0027]    Additionally, the push button unit  80  may optionally also be rotatable. That is, the top surface of push button unit  80  made may be configured with a slot or other depression into which a matching turning tool may be inserted in order to impart a torque to turn the push button unit  80 . In such an embodiment, the push button unit  80  may be depressible by the operator only after the push button unit has first been rotated into the proper position. In all other orientations, the push button unit is prevented from being depressed, and the handle  60  will not be released, as discussed below.  
         [0028]    As an example, in the embodiment shown in FIGS. 3 and 7 through  9 , the push button unit  80  must be rotated first before it may be pushed, and it includes a key cylinder that may be rotated only by inserting a key made to operate the key cylinder. When the key is inserted into the keyhole and turned, the push button unit  80  rotates from a locked position in which it may not be depressed to an unlocked position in which it may be depressed.  
         [0029]    The push button unit  80  of FIG. 3, for instance, is prevented from being depressed by the interaction of handle retention members  84  with engagement surface  64 . At least one of the handle retention members  84  of FIG. 3 is fixed and may not slide passed ridge  65  of engagement surface  64 . When the push button unit  80  is oriented so that this fixed handle retention member  84  is engaged with the engagement surface  64 , the push button unit  80  may not be depressed.  
         [0030]    As shown in FIGS. 7 and 9, the handle retention members  84  also include at least one depressible handle retention member  84 ′ which may be depressed since it is partially inset in the push button unit  80  and spring-loaded by a compression spring  86  as shown in FIG. 9. As a result of this spring-loaded effect, a sufficient downward force on the top surface of push button unit  80  can cause the depressible handle retention member  84 ′ to encounter a radially inward force from the ridge  65  of engagement surface  64  and thereby be depressed radially inward. As a result, ridge  65  is allowed to pass by the depressible handle retention member  84 ′ and handle  60  is released to spring out to its extended position under the force of torsion spring  66 .  
         [0031]    In FIG. 3, the handle retention members  84  are located on the surface of the push button unit  80 ; whereas the engagement surface  64  is located on the handle  60 . This configuration, however, could easily be reversed. That is, the fixed handle retention members  84  and depressible handle retention members  84 ′ could be mounted in the handle  60  with the engagement surface  64  and ridge  65  fashioned into the surface of the push button unit  80 . In either instance, at certain angular orientations of the push button unit  80 , the fixed handle retention members  84  interact with ridge  65  of engagement surface  64  to prevent depression of the push button unit  80 , and at another angular orientation or orientations of the push button unit  80 , the depressible handle retention members  84 ′ interact with ridge  65  of engagement surface  64  allowing the push button unit  80  to be depressed. The result is that at this latter angular orientation or orientations of push button unit  80 , an operator may depress push button unit  80  and thereby release the handle  60  from its closed position.  
         [0032]    Once released from its closed position, handle  60  is urged to an extended position where it can be rotated relative to the latch housing  15  thereby rotating the retainer unit  40 . A pair of slots  44  are formed through the lower end of retainer unit  40 . The slots shown in FIG. 3 are closed at both ends, but a pair of slots that are not closed at one or both ends could work equally as well, provided that the follower members  24  are otherwise bound to a range of motion within the slots. Also, FIG. 3 illustrates a pair of slots  44  formed through a generally hollow retainer unit  40 , but if a generally solid retainer unit  40  is employed instead, a single slot could be fashioned through the width of the retainer unit  40 , which could function equally as well. Also, a pair of grooves rather than slots could be formed on the inner or outer surfaces of retainer unit  40  to function as slots  44  as described herein.  
         [0033]    In either instance, follower members  24  extend into the slots  44  so that the torque on the retainer unit  40  is exerted on follower members  24 . Follower members  24  are also connected to shaft  50  so that the torque exerted on follower members  24  is also exerted on shaft  50 . As a result, by rotating the handle  60 , the operator rotates the shaft  50  and the pawl  90  which is mounted on shaft  50 .  
         [0034]    Additionally, in one preferred embodiment, a camming surface  22  is either machined, molding, or mounted in the first chamber  20 , such as for example being friction pressed into the chamber. In the embodiments shown in FIGS. 4 through 6, the camming surface  22  has a local minimum and a local maximum and an identical pattern on the diametrically opposed camming surface. Follower members  24  are urged up against the camming surface  22  by compression spring  26 , which may be positioned in a recess in the retainer unit  40  and forcing shaft  50  away from retainer unit  40 . In FIG. 3, for example, an embodiment of the present invention is shown in which the follower members  24  are the central portions of a cross pin  25  on either side of the axis of rotation of the shaft  50 , and the opposing ends of the cross pin  25  operate as cam followers. That is, the cross pin  25  is positioned in an orifice at the top end of shaft  50 . The cross pin  25  extends through the pair of slots  44  of the retainer unit  40 , and the ends of cross pin  25  rest on the camming surface  22 , being urged up against camming surface  22  by compression spring  26 . Thus, cross pin  25  receives an angular force through retainer unit  40  when an operator turns handle  60 , in this embodiment, and rides along camming surface  22 , thereby causing shaft  50  to move axially as well as rotate between the latched and unlatched positions.  
         [0035]    Alternatively, the shaft  50  could be connected to a second set of cross members, lugs or finger members, one pair extending through the slots  44 , and another pair resting on camming surface  22 . The embodiment shown in FIG. 3 is a presently preferred embodiment because it involves a simple configuration in which a single cross pin  25  accomplishes both of these functions. This results in relatively simple machining and assembly steps, reduces the number of required parts, and minimizes the exposure of the latch to wear and breakage. Other configurations, however, are equally contemplated by the present invention, including without limitation, using separate cross members in the place of the cross pin  25 , or housing the first compression spring  26  in the first chamber  20  rather than retainer unit  40 .  
         [0036]    In the embodiment shown in FIGS. 4 through 6, a notch  23  is added to the camming surface at each local maximum and each minimum. These notches  23  provide local stable positions for the handle-shaft-and-pawl combination within the range of operation. The notches  23  provide a “snapping” effect that is pleasant to the operator and so that the operator can tell when the pawl and shaft are in the right positions, but the notches are by no means necessary. A camming surface without notches, as well as a camming surface of different shapes and orientations, would be equally effective to impart an axial force on the shaft  50  when follower members  24  are rotated as the result of the operator rotating the handle  60 . For example, the camming surface  22  may be shaped so that the path of the pawl can overcome an obstruction on the backside of the door or frame. Also, a notch is not required at the closed position for the additional reason that the handle  60  will be returned to the longitudinal recess  14  and thereby held in place when closed unable to be rotated until push button unit  80  is depressed once again.  
         [0037]    While the present invention has been described with regards to particular embodiments, it is recognized that additional variations of the present invention may be devised without departing from the inventive concept.

Technology Classification (CPC): 8