Abstract:
An insert type of cylinder cabinet cam lock permits use of Schlage-compatible deadbolt cylinders in a cabinet door and/or drawer cam lock. A bifurcated, housing is provided that journals a cam driver adapted for operational interconnection with the Schlage-compatible standard deadbolt.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to security devices for cabinet drawers and doors. More specifically, the invention relates to pin tumbler cam locks. 
       BACKGROUND OF THE INVENTION 
       [0002]    There are two basic families of cabinet drawer and door locks: deadlocking and latch locking types of locks and cam-type locks. Both families of locks are used on cabinet drawers and doors such as those found on office desks, credenzas, and interior cabinetry. In the former family, an elongated bolt moves in a reciprocating manner into and out of a bolt housing between locked and unlocked positions, respectively, upon actuation of a key. In the latter family, an elongated bolt moves along an arcuate path, between locked and unlocked positions. In the cam family of locks, an angular rotation of 90 degrees is typically sufficient to determine the locked and unlocked positions. 
         [0003]    Both families of locks may have their bolts actuated by either pin tumbler cylinder and plug assemblies, or disk tumbler-type assemblies. The disk tumbler-type assemblies are the least expensive and historically have been used in the cam type of lock. A lock of this type is shown in U.S. Pat. No. 3,863,476 to Patriquin in which a plurality of spring-loaded plates in a plug are biased to position a protrusion from the plates into an elongated trough or cavity in an externally threaded lock body. Interference between the protrusions and sidewalls of the lock body trough prevent rotation of the plug. Upon insertion of a key into a keyway of the plug, the plates retract and the protrusions are withdrawn from the trough. Thereupon, the plug can rotate within the threaded lock body. The plug is longitudinally restrained within the lock body by a spring-loaded clip. The bolt is typically journalled for rotation with and screwed onto a longitudinal extension at the rear of the plug. A cam lock of this type is considered a “direct drive” cam lock because the bolt is directly journalled for rotation with the plug. Stated another way, consider a cam lock of the type described in which the lock is received in a desk drawer, wherein the bolt at a 12 o&#39;clock position interferes with a downwardly protruding sill or ledge in the desk. By inserting a key into the plug keyway the disk tumblers are retracted so as to be free of a trough in the externally threaded cylindrical body. Rotation of the key by 90 degrees to the 3 o&#39;clock position clears the bolt of the desk so that the drawer may be opened. The externally threaded, cylindrical lock body may be provided with a pair of internal troughs angularly spaced at 90 degrees with respect to one another so that the key may be withdrawn while the bolt is in the unlocked, 3 o&#39;clock position. Otherwise, to remove the key, the plug must be counterrotated back into the 12 o&#39;clock position leaving the bolt in the “locked position” while the drawer is still open. This procedure has the undesirable consequence in that accidentally closing the open desk drawer with the bolt locked into the 12 o&#39;clock position tends to mar the desk cabinetry. By positioning a second trough in the lock body cavity at the 3 o&#39;clock position, this result can be avoided. 
         [0004]    Over the years, it has become desirable to provide cam locks with a pin tumbler rather than a disk tumbler system. In the pin tumbler system, the disk plates are replaced with a series of cylindrical pins, which reside in bores in the plug. These “bottom pins” have differing lengths corresponding to ridges and valleys in a mating key. The lock body or cylinder is provided with a corresponding series of spring-loaded top pins, which can drop down into the bores in the plug into which the lower pins reside. When a key is inserted into the plug keyway, the top pins and bottom pins form a shear line at the interface of the plug and cylinder, allowing the plug to rotate freely. A particular problem with this type of lock is that the key can be inserted or removed only when the top and bottom pins are in alignment (typically the 12 o&#39;clock position). A rekeyable pin tumbler cam lock of this type is shown in U.S. Pat. No. 5,038,589, issued to Martin and assigned to the predecessor in interest to the assignee herein. The disclosure of said patent is incorporated herein by reference. Thus, a cam lock adapted as a pin tumbler lock will suffer from the “damaged desk” syndrome discussed above unless a means is provided for rotating and locking the bolt in respective 12 o&#39;clock and 3 o&#39;clock positions, while permitting continued rotation of the key back to the 12 o&#39;clock position. 
         [0005]    For this purpose, the so called “lazy cam” has been developed in which the bolt of a pin tumbler type cam lock is free to rotate about a protrusion extending from a rearward surface of the plug. The lazy cam, however, is journalled for rotation with the plug and drives a pin or other protrusion on the bolt. An opposite side of the bolt is typically also provided with a forwardly extending pin that cooperates with laterally extending shoulders on the rear of the cylinder so as to limit rotation of the bolt through 90 degrees. The above-described structure permits the plug to rotate through 360 degrees while the bolt rotates through only 90 degrees, thus allowing the key to be removed while the bolt remains rotationally contained between the shoulder on the cylinder and a shoulder on the lazy cam. The desk drawer can now be opened and closed with the bolt in the unlocked position with the key removed. 
         [0006]    The above-described lazy cam design provides the cam lock with all of the advantages of a pin tumbler design (e.g., ease in rekeying, possible master-keying with other cabinet drawer and door locks as well as entryway locks), which advantages are difficult to achieve or unattainable with disk tumbler-type locks. However, geometric realities prevent the bolt from being positionable anywhere other than the 12 o&#39;clock and 3 o&#39;clock positions described without changing the threaded cylinder body, so as to reposition the shoulders thereon that define the arcuate range of movement for the bolt. Alternate positioning for the bolt is desirable, as consumers have needs for cam locks having bolts that operate between the 12 o&#39;clock and 3 o&#39;clock positions; the 3 o&#39;clock and  6  o&#39;clock positions; the 6 o&#39;clock and 9 o&#39;clock positions; and the 9 o&#39;clock and 12 o&#39;clock positions as in drawer locks, left-hand door locks, tray locks, and right-hand door locks, respectively. A low-cost, rekeyable pin tumbler cam lock (ambidextrous) that addresses this problem is disclosed in U.S. Pat. No. 5,737,950 issued to Yun-Bin and assigned to the assignee herein. The disclosure of said patent is incorporated herein by reference. 
         [0007]    Thus, there are now available pin tumbler cam locks having many attributes of entryway cam locks, such as rekeyability, master-keyability, ambidextrous design, etc. However, further integration between the world of pin tumbler cam locks and entryway locks is desirable, particularly in the institutional environment. By way of example, schools, hospitals, and the like frequently have deadlocking entryway doors to classrooms, laboratories, etc. Behind these entryway doors are cabinet doors and drawers for securing biological and chemical materials, pharmaceutical products, and, with respect to casinos and the like, cash drawers. The internal entryway doors of such institutional rooms are typically keyed with so-called standard deadbolt cylinders using spring-loaded pin tumbler designs. As is well known to those of ordinary skill in the art, Schlage manufactured a highly successful standard deadbolt cylinder in which the upper and lower spring-loaded tumbler pins are contained in a unitary body. A rear end of the cylinder is engageable with a driver bar (commonly known as a “tailpiece”) that enabled the deadbolt cylinder to engage a variety of different entryway deadbolt mechanisms. Within the industry, this type of deadbolt cylinder became known by the acronym “SCDC” as a shorthand notation for “Schlage-Compatible Deadbolt Cylinder”. U.S. Pat. No. 5,657,652, issued to Martin, entitled Pin Tumbler Cabinet Door and Drawer Deadlocking Latch Lock”, demonstrates the adaptation of an SCDC (reference numeral  20  in  FIG. 4  of said patent) used in conjunction with a deadlocking cabinet door and drawer latch lock. By utilizing identical Schlage-compatible deadbolt cylinders in both entryway doors and cabinet doors and drawers of institutional organizations, a synergistic efficiency is achieved, whereby a locksmith can create one key for a classroom, hospital laboratory, or the like and allow the occupant to use the same key to open the cabinet drawers and doors as well. Nevertheless, adaptation of a standard Schlage-compatible deadbolt cylinder to a cam type of lock in an economically viable design has heretofore eluded the industry. 
         [0008]    Therefore, a need exists for an insert cylinder type cabinet cam lock that can utilize a standard Schlage-compatible deadbolt cylinder. 
       SUMMARY OF THE INVENTION 
       [0009]    It is therefore an object of the present invention to provide an insert cylinder type of cabinet cam lock that can utilize a standard Schlage-compatible deadbolt cylinder. 
         [0010]    It is a further object of the present invention to provide an insert cylinder type of cabinet cam lock that can utilize a standard Schlage-compatible deadbolt cylinder that achieves the above object and which also provides for an inexpensive method of manufacture. 
         [0011]    It is yet another object of the present invention to provide an insert cylinder type of cabinet cam lock that can utilize a standard Schlage-compatible deadbolt cylinder that achieves the above objects and that is also readily rekeyable by a locksmith in the field. 
         [0012]    The invention achieves the above objects, and other objects and advantages, which will become apparent from the description that follows, by providing an insert type of cylinder cabinet cam lock having a bifurcated case, consisting of an elongated cylinder housing portion and a mateable tailcap portion. The elongated cylinder housing defines an exposed front face having a keyway aperture for receipt of the keyway end of a standard Schlage-compatible deadbolt cylinder or the like. The elongated cylinder housing further defines a main body and a distal rear end, each adapted for removable rearward receipt of the conventional insert deadbolt cylinder. The tailcap portion forms an internal cavity having a rear wall defining a hub for journalling a cam driver for rotary motion with respect thereto. A front open end of the tailcap is adapted to be received on the rear end of the cylinder housing. A specially designed cam driver has a forward end adapted for cooperative receipt in the rear end of the conventional insert type of deadbolt cylinder and a distal end adapted to receive and drive (indirectly) a conventional cam bolt. The distal end of the cam driver passes through the tailcap hub so that the cam bolt is removably journalled to the cam driver external to the bifurcated cam lock case. A threaded pin or the like may be used to secure the tailcap to the cylinder housing and also to limit rotation of the cam bolt to a prescribed range. 
         [0013]    In preferred embodiments of the invention, a conventional lazy cam may be journal led to the cam driver and operatively connected with the cam bolt so as to drive the cam bolt in the conventional manner. 
         [0014]    In alternate embodiments of the invention, the insert type of cylinder cabinet cam lock is usable with large format-interchangeable cores, such as those manufactured by Schlage. In this embodiment, a cam driver having a different front end design is used having transverse rebates on the front end thereof for receipt of a conventional (but shortened) driver bar (or tailpiece). 
         [0015]    In either embodiment of the invention, both the cylinder housing and tailcap have at least partially, substantially continuous cylindrical surfaces with synchronized external threads thereon for receipt of a conventional, cooperatively threaded nut to secure the lock case to a cabinet door or drawer. In addition, the externally threaded cam lock may also be received in a conventional threaded receptacle for an entryway deadbolt so as to convert such an entryway to a cam locking entryway door. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is an exploded, top right perspective view of an insert type of cylinder cabinet cam lock in accordance with the principles of the invention. 
           [0017]      FIG. 2  is a top left rear perspective view of the elongated cylinder housing shown in  FIG. 1 . 
           [0018]      FIG. 3  is a rear elevational view of a conventional Schlage-compatible deadbolt cylinder shown in  FIG. 1 . 
           [0019]      FIG. 4  is a front elevational view of the tailcap shown in  FIG. 1 . 
           [0020]      FIG. 5  is rear elevational view of the cam driver shown in  FIG. 1 . 
           [0021]      FIG. 6  is a front elevational view of the cam driver shown in  FIG. 1 . 
           [0022]      FIG. 7  is top left rear isometric view of an alternate embodiment of the cam driver shown in  FIG. 1 . 
           [0023]      FIG. 8  is a top left perspective view of a driver bar for use with the alternate embodiments of  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0024]    An insert type of cylinder cabinet cam lock in accordance with the principles of the invention is generally indicated at reference numeral  10  in the various Figures of the attached drawings wherein numbered elements in the Figures correspond to like numbered elements herein. 
         [0025]    The cam lock is substantially bifurcated as will be explained further herein below and includes an elongated cylinder housing  12  having a front face  14  defining a keyway aperture  16  and a circumferential rim  18  extending beyond a main body, generally indicated at reference numeral  20  in  FIG. 1 . The main body is generally cylindrical in shape, having external threads  22  on cylindrical portion thereof and generally flat, non-threaded sidewalls  24 , as best seen in  FIG. 2 . As will be understood by those of ordinary skill in the art, the external threads  22  on the generally cylindrical portions of the main body are adapted to receive a conventional nut for securing the main body to a cabinet door or drawer or, alternatively, into the standard, threaded receptacle of an entryway door deadlock. The main body further includes a distal rear end  26  defining a substantially radially inward rebate generally circumferentially around the entire rear end  26 . The main body  20  and rear end  26  are adapted to rearwardly receive a conventional insert-type deadbolt cylinder  30  through a rear aperture  32  and an intersecting vertical slot  34 . A cylindrical bore extends from the rear aperture  32  through the keyway aperture  16 , such that a keyway face  36  of the deadbolt cylinder  30  is received substantially flush with the front face  14  of the main body  20  in the conventional manner, while the vertical slot  34  receives an upper pin housing  38  of the deadbolt cylinder  30  in the conventional manner. The main body  20  is preferably manufactured from a die-cast alloy, such as zinc, or may be machined from brass or steel. 
         [0026]    A substantially cylindrical cam driver  40  has a forward end  44  adapted for cooperative engagement with a rear end  46  of the deadbolt cylinder  30 , as best seen in  FIG. 3 . As best seen in  FIG. 6 , the adaptation includes a hemicylindrical axial protrusion  48 , including a central bulge  50  for mating with the rear end  46  of the deadbolt cylinder  30 . A low-friction spacer or washer  52  is preferably interposed between the cam driver  40  and the rear end  46  of the deadbolt cylinder  30 . Th cam driver  40  is also provided with a radially extending, circumferential flange  54  on the forward end  44 , to support the washer  52 , and for other purposes, as will be described further hereinbelow. 
         [0027]    The cam driver  40  is contained in a cavity generally indicated at reference numeral  56  in a tailcap  60  having an external profile substantially identical to that of the main body  20  of the cylinder housing  12 . The cavity is defined by substantially vertical sidewalls  62 , and by a substantially planar rear wall  64  defining a cam driver hub or aperture  66  in a lower portion thereof. The hub  66  forms a journal for the cam driver  40  for rotation. A circumferential groove  68  about the hub  66  forms an axial bearing surface for the flange  54  on the cam driver  40 . Sidewalls  62  of the tail cap  60  are sized to fit closely about the rebate  28  on the main body rear end  26  such that the cam driver  40  and washer  52  are substantially contained within the cavity  56 , and the main body  20  and tailcap  60  form a substantially continuous external surface. In this way, external threads  70  on the tail cap  60  cooperate with the external threads  22  of the main body for application of a cooperatively threaded nut (not shown), as previously described. In order to retain the tailcap  60  on the cylinder housing  12 , the rear end  26  of the cylinder housing  12  is provided with a pair of longitudinal, threaded bores  72  and the tailcap  60  is provided with a pair of corresponding apertures  74  in the rear wall  64  of the tailcap. As best seen in  FIG. 1 , a threaded pin  80  having a circumferential shoulder  82  and a rearwardly extending portion  84  may be inserted through either aperture  74  and into a corresponding one of the threaded bores  72  such that the shoulder  82  urges against an external surface of the rear wall to retain the tailpiece  60  with respect to the cylinder housing  12 . 
         [0028]    As will be appreciated by those of ordinary skill in the art, the cam driver  40  has a distal end  86  that protrudes from the cam driver hub  66  when the lock  10  is assembled. The distal end is provided with a conventional tenon  88  that axially, rearwardly protrudes from both the cam driver distal end  86  and the rear wall  64  of the tailpiece  60 , along with a further portion of the cam driver  40 , such that the conventional cam bolt  90 , having a conventional transverse pin  92  and cam bolt aperture  96 , may be freely received on the extending portion of the cam driver  40  so as to rotate thereabout. A conventional lazy cam  98  has a conventional mortise  100  for journalling the lazy cam with the tenon  88  so that the lazy cam is journaled to and rotates with the cam driver  40 . The transverse pin  92  on the cam bolt  90  may be engaged with the lazy cam, as is well known by those of ordinary skill in the art, so as to be either a direct drive or indirect drive. As best seen in  FIGS. 1 and 5 , a conventional screw  110  secures the lazy cam  98  and cam bolt  90  to the cam driver  40  by way of a conventional threaded hole  112  in the distal end  86  of the cam driver  40 . 
         [0029]    As will be appreciated by those of ordinary skill in the art, the cam lock  10  shown in the illustrated Figures permits a conventional insert type of deadbolt cylinder  30  to be utilized in a cam lock environment. In this way, the same key that is utilized for an entryway deadbolt, utilizing the insert type of deadbolt cylinder  30 , can also be used to operate the cam lock  10 , which has been keyed with an identical type of deadbolt cylinder, as is the entryway door. As a result, a hospital or pharmacy entryway door can be keyed alike with cabinet doors and drawers employing the inventive cam lock  10 , as well as retractable-style cabinet drawer and door locks also employing the insert type of deadbolt cylinder  30 , such as that shown at reference numeral  20  in U.S. Pat. No. 5,657,652, issued to Martin on Aug. 19, 1997, the disclosure of which is incorporated herein by reference. 
         [0030]    Those of ordinary skill in the art will conceive of other alternate embodiments of the invention upon reviewing this disclosure. In one alternate embodiment shown in  FIG. 7 , the cam driver  40  of the above embodiment is replaced with an alternate cam driver  40  for use with a conventional blade like driver bar such as shown at reference numeral  188 ′ in  FIG. 8 . In the alternate end  44 ′ of the cam driver  40 ′ may be provided with orthogonal rebates  120  to receive the bladelike driver bar (not shown) described above. In all other respects, the remaining elements of the alternate cam driver  40 ′ are similar to those shown at reference numeral  40  of the first preferred embodiment. Thus, the invention is not to be limited to the above description, but is to be determined in scope by the claims that follow.