Patent Abstract:
A sash lock for use with door and window is provided. The lock has a base housing shaped into a laterally extending crib to contain a partially protruding plunger sliding under a forward bias, a large button block that occupies a substantial area at the top of the lock to allow for a unique squeeze release of the plunger and translates in a perpendicular plane with respect to the plunger movement under an expansive bias for normally pushing the button block away from the base housing in cooperation with the biased counteraction of the cam surfaces of the plunger but yielding to a manual depression to activate the plunger through a cam engagement, and a top housing fastened to the base housing to enclose the plunger and button block. The plunger has cam surfaces at a rear end facing forwardly and a beveled lip portion at a front end while the button block has a beveled surface facing the cam surfaces of the plunger. The sash lock further comprises two identical holes formed in the bottom of base housing and a separate keeper for interlocking with the base housing.

Full Description:
BACKGROUND OF THE INVENTION 
   A. Field of the Invention 
   The present invention relates to door and window hardware. More particularly, the present invention relates to a mechanically stable and ergonomically improved door and window sash lock. 
   B. Description of the Prior Art 
   Sliding windows or patio doors in a building are made for letting in necessary light and air into the room while allowing occupants to have a comfortable viewing of the surrounding nature. At the same time, such doors or windows should be able to lock out harmful elements and potential intruders. 
   Window latches and locks that are also applied to doors have been developed as the windows in the modernized buildings have long been evolved all together. Of different types of slider window, a single-hung type window is structured to have an upper outside pane in a stationary sash and an inside pane in a sliding sash guided in a window frame along its vertical path between a raised level positioned over the upper sash to half open the window and a lowered position to close the window opening in cooperation with the upper sash. A double-hung type window has two vertically sliding sashes movable in parallel planar paths in a single frame. There are also horizontal sliders. A gliding window has two sashes with at least one sliding horizontally past the other. The respective sashes of the double-hung windows may be made to swing inwardly for the purpose of a safe cleaning but they must be returned to their vertical abutting positions when the window is to be locked. Normally, in the closed position, the mating sashes have the respective proximal sides overlapped to offer the necessary sealing. Therefore, most latches are conveniently positioned near the meeting areas of the two sashes at the exposed surface of the inner sash while the mating keeper or strike is fixed to the accompanying outer sash. 
   Known latches for windows have their inherent drawbacks. Automatic window sash locks as depicted in U.S. design Pat. No. 395,222 to Fountaine comprise a main latch body attached to a slide-open sash for automatically engaging a fixed keeper on the companion sash or the sash itself that incorporates in its profile a notch so that the sashes are immobilized in the frame when the window is closed. Such sash locks generally include a user-operated component handle to release the automatic locking mechanism, which only needed the sliding closure of the sash to push in a bolt of the sash lock before it protrudes back into engagement with the keeper or notch. To streamline the one-handed user operation in lift or sideway slide opening of the window, the release handle or lever of the sash locks is adapted to be depressed by index to little fingers while the thumb presses on the underside of the proximal sash part to release the lock and slide the sash in one action. 
   However, the lever needs a substantial projection from the main latch body taking up space upward as well as toward the user for the bolt to create a proper lever or bolt action inside the latch device. This makes a bulky and unappealing lock structure that sticks into the viewing area of glass panes. Under the superficial problem lies a mechanical disadvantage to have to apply a large circular force to retract a locking bolt out of engagement with the counterpart of the other sash. For the internal actuator to move the bolt easily, the lever must extend above and beyond the latch device itself as long as possible. However, such deflecting lever movements produce a long-term adverse force against the secure joint between the latch device and sash during their combined lifetime because normally there is only a couple of fasteners to endure the releasing depressions at repeated window openings. 
   Hence, there is need for a small form factor sash lock that is not only visually unobtrusive but also mechanically stable and ergonomically fit. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing, the object of the preset invention is to provide a compact sash lock that locks automatically and is squeezable directly over almost its entire body to actuate the release mechanism requiring no defecting actuators or handles. 
   Another object of the present invention is to provide a fail-safe locking mechanism for door and window sashes which is easy to manufacture. 
   A sash lock of the present invention is for use with door and window sashes and it has a base housing having an elongated planar bottom with two tubular posts located near further lateral ends of the bottom to support fasteners for mounting the sash lock on a first inner sash member sliding in relation to a second outer sash member. Around the bottom of base housing an upright front wall with an elongated aperture and connecting side and rear walls encircle and a supporting topography is integrally formed inside of the walls. 
   A plunger is slidably supported in the base housing to move linearly under a forward bias and has cam surfaces at a rear end facing forwardly and a beveled lip portion at a front end protruding through the front aperture of the base housing. 
   A large button block extends laterally over the tubular posts of the base housing and has a beveled surface facing the cam surfaces of the plunger and two opposite end tunnels to fit snugly over the tubular posts for maintaining linear translations perpendicular to the moving direction of the plunger under an expansive bias for normally pushing the button block away from the base housing in cooperation with the biased counteraction of the cam surfaces of the plunger. The button block has a height greater than that of the surrounding walls of base housing. Then, a top housing is fastened to the base housing to enclose the plunger and button block allowing them to move within the respective ranges of translation. 
   The sash lock further comprises two identical holes formed in the bottom of base housing at both sides of the aperture and a separate keeper for mounting on the second outer sash member. The keeper has a strike plate that extends in parallel with the front wall of base housing when it is mounted on the outer sash member, a beveled surface at a distal edge of the strike plate to face the beveled lip portion of the plunger, two opposite legs at a proximal edge of the plate to define a large rectangular notch into which the plunger protrudes, an L-shaped bracket joined to distal ends of the legs for supporting fasteners threaded though the second sash member and a double catch shaped to hook in the two bottom holes of the base housing as the plunger rides over the strike plate at the meeting of their beveled surfaces. Therefore, the lock can make a complete three dimensional locking engagement with the keeper until an inside occupant of the inner sash member gently grabs the inner sash and the button together to release the plunger and start sliding the sash at the same time. 
   The forward bias of the plunger and the perpendicular expansive bias of the button block are produced by two pairs of identical helical springs held in the respective positions at first ends by topographic peaks and valleys of the base housing and complementary protrusions of the top housing and at the opposite second ends through insertion into slots formed in the plunger and the button block to keep a balanced actuation of the button block and plunger. 
   The plunger is kept in fore and apt translations in one plane by two side upright walls from the base housing and in another perpendicular plane by a flat area of the base housing bottom and complementary guide plates from the top housing. 
   Embodiments of the invention will now be described by way of example with reference to the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation view of a compact sash lock installed according to the present invention. 
       FIG. 2  is an exploded perspective view of the sash lock of  FIG. 1  showing all of the components. 
       FIG. 3A  is an enlarged perspective view of the latch unit with an upper housing removed to show in detail the positional relations of components within a base housing. 
       FIG. 3B  is a perspective view of the upper housing to mate with and close the base housing. 
       FIG. 4  is a cross sectional view along the frontal median lines of the keeper and latch unit of  FIG. 2  after assembly. 
   

   Similar reference numbers denote corresponding features throughout the attached drawings.
       16  Upper Sash     12  Window     38  Glass Pane     34  Beveled Surface     10  Sash Lock     22  Button     11  Latch Unit     36  Double Catch     14  Lower Sash     20  Seal     42  Lip     24  Meeting Rail     44  U-Shaped Interlock     24  Groove     94  Screw     82  Upper Housing     88  Mounting Post     90  Vertical Tunnel     50  Base Housing     92  Guiding Post     86  Assembly Screw     26  Plunger     132  Strike Plate     134  Leg     32  Keeper     140  Screw Slot     136  Notch     138 L. Bracket Portion     112  Bump     102  Push Blade     108  Tip     99  Block Section     100  Blind Hole     91  End Leg     54  Upright Wall     74  Beveled Surface     62  Lip Portion     68  Aperture     64  Stop     70  Hole     66  Front Wall     84  Screw Hole     52  Bottom     128  Sidewall     50  Base Housing     96  Spring     76  Spring     80  Block     98  Column     130  Rear Wall     82  Upper Housing     188  Recessed Wall     106  Opening     126  Lip     122  Guide Plate     60  Cam Surface     58  Foot     124  Stake     120  Recessed Wall     116  Bump     140  Screw Slot   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIG. 1 , a window lock assembly  10  of the present invention generally comprises a latch unit  11  and a keeper  32  and is made for a sliding window  12  that may includes a rectangular inner lower sash  14  shown at its top cross sectional area and a similarly shaped outer upper sash  16  shown at its bottom cross sectional area for mating with the lower sash  14  to close window  12  as the lower sash  14  slides over the upper sash  16  in a window frame (not shown). Lower sash  14  encases downwardly extending glass panes  18  and a sealing  20  between the panes  18 . In the window  12  illustrated, latch unit  11  may be mounted on the top middle surface of lower sash  14 . 
   Besides covering the interior room of a building from the elements, window  12  may obtain an improved security and aesthetic value from the sash lock  10  that may be installed initially at the time of building a house or home improvements wherein the owner may replace the old bulky locking devices with this mechanically reliable and yet more compact sash lock  10 . With functionally and ergonomically advanced quality, the installed sash lock  10  will blend well with the surrounding window sashes and does not create a physical interference with handling the sashes in opening and closing the window while allowing an uninterrupted view due to its low and thin profile lodged within a small confinement between the two sashes  14  and  16 . With the complete renovation from the known cam lock mechanisms, lock assembly  10  of the present invention has come to have no conventional deflected lever projection any more. Instead, it provides an oversized push button  22  to be depressed directly toward lower sash  14  in its longitudinal direction so that the user intuitively grabs button  22  together with the underlying sash  14  to lift the same in the normal course of opening the window  12 . No extra manipulations to release sash lock  10  are necessary. Because button  22  is depressed within the area of latch unit  11  of the sash lock  10  and in direct alignment with lower sash  14  the attachment of latch unit  11  to sash  14  stays firm over long time. 
   Facing opposite to lower sash  14 , the upper sash  16  has a horizontal upper groove  24  for receiving a spring-loaded plunger  26  of latch unit  11  through the interlocking keeper  32 , which is affixed into groove  24  and provides a beveled surface  34  for interacting with plunger  26  and a double catch  36  for immobilizing latch unit  11  and lower sash  14  completely. 
   Upper sash  16  may be stationary encasing upwardly extending glass panes  38  and a sealing  40  between the panes  38  although mechanisms are known to inwardly swivel and/or slide up down both sashes  14  and  16 . In the double-hung type window  12  illustrated, latch unit  11  may be mounted on the top middle surface of lower sash  14 . Along the outer side of lower sash  14  extends a downward lip  42  for mating with a U-shaped interlock  44  of the meeting rails made of sashes  14  and  16  in order to provide the preliminary security as well as weather sealing. The plunger  26  may be made of zinc. The metallic plunger  26  has a hardness, which provides wear-resistance to the repeated engagement with keeper  32  or the upper sash  16  at the groove  24  in case keeper  32  is not present. 
     FIG. 2  depicts the overall construction of latch unit  11  and its interlocking keeper  32 . A major component of latch unit  11  is a base housing  50  that may be made of a die-cast metal in the shape of a generally rectangular crib having various anchor means for holding moving parts in the latch unit  11 . 
   The housing  50  and the rest associated parts constituting latch unit  11  are formed symmetrical with reference to the frontal meridian line (not marked) of the unit  11  in order to keep balanced latching actions in cooperation with the similarly symmetrical keeper  32 . Mounted on the bottom  52  of base housing  50  is the twin cam plunger  26  adapted to slide horizontally through housing  50  within a straight track formed by two side upright walls  54  distanced equally from the meridian line of unit  11  as better shown in  FIG. 3A . 
   Plunger  26  is generally U-shaped with two legs  56  extending toward the interior of housing  50  and terminated by feet  58 , respectively. Each of the feet  58  has a top cam face  60  to be actuated by a vertical downward depression to provide a retracted position of plunger  26 . The feet  58  of plunger  26  are connected by a lip portion  62 , which is movable between an extended position shown in  FIG. 2  and the same retracted position of plunger  52 . Extension of plunger  26  is limited by two opposite side stops  64  integrally formed to plunger  52  for abutment at the inner surface of a front upright wall  66  of housing  50 . To allow the protrusion of lip portion  62 , front wall  66  has a vertical rectangular aperture  68  centrally positioned. Identically formed in bottom  52  at both sides of aperture  68  are horizontal rectangular holes  70  for accepting vertical double catch  36  of keeper  32  to provide an omni-directional locking engagement between unit  11  and keeper  32  that is very difficult to break. In order to take advantage of double catch  36  combined with rectangular holes  70 , latch unit  11  may be fastened to sash  14  slightly overhanging as illustrated in the drawings. 
   The top surfaces of plunger  26  are flat save cam faces  60  and a selected cutout  72  that reduces the weight of plunger  26 . Of the bottom surfaces of plunger  26 , lip portion  62  has a beveled surface  74  around its lower front corner for cooperating with the corresponding surface of keeper  32 . Then, two expansion springs  76  are inserted into the legs  56  through bores  78  that extend almost the length of the legs  56 , respectively as shown in cross section in  FIG. 4 . The outer free ends of springs  76  are each kept in place by a couple of small blocks  79  and  80  formed integral to housing  50  at side-by-side positions. An upper housing  82  for closing base housing subsequently closes the top open space between blocks  79  and  80  as will be described below. Therefore, twin cam plunger  26  is always urged outwardly to protrude into engagement with keeper  32  when they slide into a meeting position. 
   In addition, two screw holes  84  are formed in bottom  52  near its lateral edges to permit two assembly screws  86  to be respectively driven up to downwardly extending mounting posts  88 , which are integrally formed on upper housing  82  to permanently enclose the various components of latch unit  11  within a partially closed space between the two housing members  50  and  82 . 
   The separately formed button  22  is responsible to activate plunger  26  by pushing back the cam faces  60 . Button  22  may be made of a single metal block spanning almost the entire length of the housing  50  or  82 . Button  22  is elongated laterally and relatively higher than wall  66  of base housing  50 . In addition, button  22  has twin vertical tunnels  90  through its opposite end legs  91  for snuggly receiving two upright guiding posts  92  that double as screw supports for two mounting screws  94 , which can be easily driven from above the completed sash lock  10  through posts  92  and then into lower sash  14 . Each post  92  may have a funnel-shaped top surface to conform to the conical surface of screw  94  for a firm engagement. 
   At the same time, button  22  is held in a balanced posture by two upright suspension springs  96 , which are anchored on round columns  98  formed on housing bottom  52  inwardly of guiding posts  92 . The combined expansive force of springs  96  is determined to be just enough to counter the gravity at button  22  plus a relaxed exertion of manual push to ensure a pleasant manual actuation of button  22  as well as the uninterrupted automatic advancement of plunger  26  into the locking position by the horizontal plunger springs  76 . 
   Button  22  also has left and right block sections  99  with respective blind holes  100  formed concentrically to columns  98  for holding upper portions of springs  96  so that springs  96  are secured between base housing  50  and button  22 , which are always urged away from each other. Extending lengthwise underside of button  22  is a push blade  102  beveled for engaging both cam surfaces  60  at the same time to retract plunger  26  when button  22  is depressed. 
   Additionally, in the front middle area of button  22  there is formed a stern  104  that conveniently enlarges the area of button  22  to be contacted by the operator&#39;s hand and helps assist button  22  in maintaining its vertical translations along the guiding posts  92  as stem  104  keeps sliding contacts with upper housing  82  through its large opening  106  that conforms to the general circumferential profile of button  22  as shown in  FIG. 3B . Stem  104  gradually converges and is bordered by a blunt tip  108  with round sides  110  that altogether extend vertically downwardly. Preferably, stem  104  is hollow to keep button  22  light. 
   Button  22  has two side bumps  112  on its front vertical walls  114  ( FIG. 3A ) and a similar middle bump  116  at its rear lower edge ( FIG. 4 ) in order to limit its upward translation by abutting the respective recessed walls  118  formed on upper housing  82  near the front section of opening  106  and a similar recessed wall  120  located at the same height of walls  118  close to the rear middle section of opening  106 . 
   The thus constructed button  22  can hold itself in the assembled position in base housing  50  while the respectively spring loaded plunger  26  and button  22  are both encased by upper housing  82 , which is secured using the assembly screws  86 . Depending from the bottom surfaces of button  22  are a pair of guide plates  122  for holding down legs  56  of plunger  26  and another pair of rear stakes  124  to run over springs  76  placed between the open blocks  79  and  80  to secure the distal ends of springs  76 . In order to facilitate assembly of upper housing  82  onto base housing  50 , upper housing  82  has an alignment means of discrete downward lips  126  along the lower peripheral surfaces to fit snugly in the interior of surrounding walls of base housing  50  which comprises front wall  66 , two side walls  128  and a rear wall  130 . 
   Keeper  32  comprises an upright strike plate  132  having beveled surface  34  at the top edge and two opposite legs  134   a ,  134   b  at the bottom to define a large rectangular notch  136  into which plunger  26  clicks to keep latch unit  11  in a locked position automatically after plunger  26  rides over strike plate  132  at the meeting of their beveled surfaces  74  and  34 . Extending integrally from the bottom of strike plate  132  is an L-shaped bracket portion  138  with at least two screw slots  140  for fastening plate  132  to upper sash  16  shown in  FIG. 1 . Screw slots  140  are carefully positioned in bracket portion  138  to permit unobstructed access of fastening screws through notch  136  at installation. 
   The double catch  36  comprises two upturned hooks stemming from legs  134   a  and  134   b . When latch unit  11  goes into the locked position, double catch  36  comes to penetrate into the holes  70  of base housing  50  in order to further lock the unit  11  and sash  14  horizontally over the primary vertical latching engagement of plunger  26 . Therefore, latch unit  11  can make a complete three dimensional locking engagement with keeper  32  until an inside occupant of the window  12  gently grabs the lower sash  14  with button  22  to release plunger  26  and start sliding the sash  14  at the same time. 
   Therefore, while the presently preferred form of the sash lock has been shown and described, and several modifications thereof discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims. 
   For example, as a matter of simply changing the orientation, the same sash lock  10  may be mounted to a laterally sliding sash door at the interior side following the illustrated mounting method in order to obtain the equally improved benefit of the present invention.

Technology Classification (CPC): 4