Abstract:
A re-keyable lock cylinder assembly is provided which includes a cylinder housing and a cylinder plug rotatably supported in the cylinder housing. A tumbler pin assembly includes a pair of pins disposed and slidably supported within a pin bore formed in the cylinder plug and a coupling element interposed between the pair of pins and selectively rotatable between a coupled position wherein the pair of pins are fixed with respect to one another and a free position wherein the pair of pins are positionable with respect to one another for varying a height of the tumbler pin assembly.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to lock cylinders, and more particularly, to an improved rekeyable lock cylinder.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is well known in the art to provide a door hardware assembly that is operable to maintain a door in a closed position by selectively securing the door to a doorframe. It is equally well known to provide a door hardware assembly that is capable of being locked to selectively prevent operation of the door hardware assembly. As can be appreciated, by preventing operation of the door hardware assembly, the door will remain closed and in a locked condition. Such conventional door hardware assemblies generally include a handle assembly, lock cylinder, and key, whereby the key is operable to selectively lock the lock cylinder to prevent operation of the door handle assembly and maintain the door in the closed and locked condition.  
         [0003]     The lock cylinder includes a cylinder plug rotatably supported in a cylinder housing. A set of pins extend between the cylinder plug and the cylinder housing to selectively lock and unlock the lock cylinder. The lock cylinder is designed to matingly receive a key, whereby the key is operable to change the lock cylinder between a locked and unlocked condition. As can be appreciated, the key is specific to the particular lock cylinder so as to prevent unwanted operation of the door handle assembly.  
         [0004]     The lock cylinder commonly includes a plurality of pin assemblies, whereby each pin assembly includes an upper pin slidably disposed within an upper bore formed in the cylinder housing and a lower pin slidably disposed within a lower bore formed in the cylinder plug. A shear line is defined between the cylinder plug and cylinder housing. The key is used to selectively lock and unlock the lock cylinder, whereby raised portions or bitings disposed on the key are operable to engage the upper and lower pins to properly align the pin interface with shear line to permit rotation of the cylinder plug within the cylinder housing. It may be desirable to “reset” or “rekey” the lock cylinder, without having to replace the entire mechanism. Rekeying of a conventional lock cylinder provides the lock cylinder with a new key that is operable to lock and unlock the re-configured lock cylinder, while concurrently prohibiting further use of the old key.  
         [0005]     In a re-keying operation, the upper and lower pins are replaced to vary the relative heights of each of the upper and lower pins which corresponds to the new key. In this regard, a new key having raised portions or bitings commensurate with the new pin heights of each pin assembly, is required to properly align the pin interface within the shear line. Once the new pins are installed, the lock cylinder will no longer permit rotation of the door handle assembly if the old key is used in the lock cylinder. As can be appreciated, the old key is not commensurate with the new pin heights, and therefore will not properly align the first and second shear zones of the respective pin assemblies.  
         [0006]     the cylinder housing and a lower tumbler pin assembly having a pair of pins disposed and slidably supported within a pin bore formed in the cylinder plug. A coupling element is interposed between the pair of pins and selectively rotatable between a coupled position wherein the pair of pins are fixed with respect to one another and a free position wherein the pair of pins are positionable with respect to one another for varying a height of the tumbler pin assembly. A camming system is operably coupled between the cylinder housing and the tumbler pin assembly to enable selective rotation of the coupling elements between the coupled position and the free position.  
         [0007]     In accordance with one aspect of the present invention, a method of rekeying a lock cylinder is provided in which a valid key is inserted into a keyway in a cylinder plug so that the cylinder plug can be rotated with respect to the cylinder housing from a home position to a learn position. A pin assembly within a pin bore formed in the cylinder plug is rotated from a fixed position to a free position such that a height defined by first and second pins of the pin assembly is adjusted. The valid key is extracted from the keyway and a replacement key is inserted into the keyway. The pin assembly is rotated within the pin bore to the coupled position to fix the height of the pin assembly. The cylinder plug is rotated to the home position and the replacement key is removed.  
         [0008]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0010]      FIG. 1  is a respective view of a lock cylinder in accordance with the present invention;  
         [0011]      FIG. 2  is an exploded perspective view of the lock cylinder shown in  FIG. 1 ;  
         [0012]      FIG. 3  is an exploded detail view of a tumbler pin assembly in accordance with the present invention;  
         [0013]      FIG. 3A  is a cross-sectional view of the pin carrier shown in  FIG. 3  taken along line A-A;  
         [0014]      FIG. 3B  is a cross-sectional view taken of through inner pin illustrated in  FIG. 3  taken along line B-B;  
         [0015]      FIG. 4  is a partial cross-sectional view of the lock cylinder illustrated in  FIG. 1  taken along line  44 ;  
         [0016]      FIG. 5  is a partial cross-sectional view of the lock cylinder shown in  FIG. 1  taken along line  5 - 5 ;  
         [0017]      FIG. 6  is a partial cross-sectional view similar to  FIG. 4  in which the lock cylinder has been placed in the learn mode;  
         [0018]      FIG. 7A  is a partial perspective view of the lock cylinder illustrated in  FIG. 1  rotated to a locking mode; and  
         [0019]      FIG. 7B  is a partial perspective view of the lock cylinder illustrated in  FIG. 1  in a learn mode. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]     The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0021]     With reference now to the drawings, lock cylinder assembly  10  includes a cylinder housing  12  having a cylindrical cavity  14  formed along a longitudinal axis thereof and a cylinder plug  16  having a keyway  18  formed along the longitudinal axis thereof which is rotatably supported within the interior cavity  14  of the cylinder housing  12 . A chimney  20  extends upwardly from cylinder body  22 . A set of pin bores  24  extend through chimney  20  and terminate at interior cavity  14 . Likewise, a set of pin bores  26  are formed in cylinder plug  16  to extend between keyway  18  and an outer surface of the cylinder plug  16 . As previously indicated the cylinder  16  is rotatably supported within the cylinder housing  12  such that pin bores  24  formed in chimney  20  are aligned with pin bores  26  when the cylinder plug  16  is in a home position.  
         [0022]     Lock Cylinder assembly  10  further includes a set of tumbler pins  28  and a set of springs  30  disposed and slidably supported within pin bore  24  at cylinder housing  12 . A cap  32  is disposed on top of chimney  20  for releasbly  
         [0023]     As presently preferred, the coupling element takes the form of an arcuate gear set. Specifically with reference to  FIG. 3A , a gear-like rack  52  is formed on an inner surface  54  defined by blind bore  44 . The arcuate rack  52  extends approximately 90° around the inner surface  54 . A complimentary gear rack  56  is formed in an outer surface  58  of pin body  48  over approximately 90° of the outer surface  58 . Thus, pin carrier  36  may be rotated relative to inner pin  38  through approximately 90° for coupling and uncoupling the tumbler pin assembly  34 .  
         [0024]     Pin carrier  36  has a cam arm  60  extending from carrier body  42 . A comb  62  having a set of fingers  64  extends through a set of apertures  66  formed in cylinder housing  22  and a set of apertures  68  formed in cylinder plug  16  so as to engage cam arm  60  as best seen in  FIG. 4 . Apertures  68  formed in cylinder plug  16  are generally L-shaped to afford relative rotation of the cylinder plug  16  within cylinder housing  12  and at the same time afford axial movement of the cylinder plug  16  within cylinder housing  12  when the lock cylinder  10  is in a learn mode. Specifically, with reference to  FIG. 4 , fingers  64  of comb  62  extend into cylinder plug  16  so as to engage cam surface  70   a  formed on cam arm  60 . As cylinder plug  16  moves axially (to the left as shown in  FIG. 4 ) with respect to housing body  22 , fingers  64  cooperate with cam arm  70   a  to rotate pin carrier  36  (in a clockwise direction as shown in  FIG. 4 ), thereby decoupling the inner pin  38  from the pin carrier  36 . Likewise, axial movement of the cylinder plug  16  (to the right as shown in  FIG. 16 ) causes the fingers  64  to engage cam surface  70   b , thereby rotating the pin carrier  36  in a counterclockwise direction (as shown in  FIG. 4 ) causing gear rack  52  to engage gear rack  56 , and couple pin carrier  36  and inner pin  38 .  
         [0025]     Comb  72  is disposed on a side of housing body  22  opposite comb  62 . Comb  72  has a set of fingers  74  extending therefrom which are adapted to be received through a set of apertures  76  formed in housing body  22  and a set of apertures  78  formed in cylinder plug  16 . Fingers  74  extend through apertures  78  to impinge upon the pin carrier  36  and maintain the tumbler pin assembly  34  in a coupled position when the lock cylinder  10  and not the learn position (i.e., in the home position or the upright position).  
         [0026]     With reference now to  FIGS. 1 and 5 - 7 B, operation of lock cylinder  10  will now be described. Initially the lock cylinder  10  is in a home position as illustrated in  FIG. 1 . Upon insertion of key K into keyway  18 , the pin extension  50  on tumbler pin assembly  34  cooperate with the bitings formed on the key K for positioning pins  28  and  34  within the lock cylinder  10 . When an authorized key is inserted, the bitings in the key K correspond to the height of tumbler pin assembly  34  such that the interface between pin extension  46  and pin  28  align along the shear interfaces between the cylinder housing  12  and the lock plug  16 . So aligned, the cylinder plug  16  may be rotated in a counter-clockwise direction relative to the cylinder housing  12  towards an operation position (as best shown in  FIG. 7A ) and rotated in a clockwise direction to a home position as illustrated in  FIG. 1 .  
         [0027]     To place the lock cylinder  10  into a learn mode, an authorized key K is inserted into the keyway  18  thereby permitting relative rotation of the cylinder plug  16  within cylinder housing  12  in a clockwise direction as shown in  FIG. 7B . Once in the learn position, the cylinder plug  16  may be pushed axially into the interior cavity  14 . This axial movement of the cylinder  16  relative to the cylinder housing  12  causes fingers  64  on comb  62  to engage cam surface  70   a , thereby rotating pin carrier  36  relative to inner pin  38  to uncouple these components of the pin tumbler assembly  34 . At this point, key K is withdrawn from keyway  18 . The absence of key K in keyway  18  allows pin carrier  36  and inner pin  38  to slide relative to one another in opposite directions such that the height of tumbler pin assemblies  34  are reset. Next, a new key is inserted into keyway  18  causing inner pin  38  to move with respect to pin carrier  36 , thereby adjusting the height of the tumbler pin assembly  34  to configure the lock cylinder  10  so as to be operable by the new key. At this point, cylinder plug  16  is moved axially with respect to cylinder housing  12  and rotated in a counterclockwise direction back to the home position. Through this operation, lock cylinder  10  has been rekeyed to be operable with a new key.  
         [0028]     The present invention has been described with reference to a preferred embodiment. However, one skilled in the art will recognize that the present invention may be modified without departing from the spirit and scope of the invention. For example, the preferred embodiment discloses a camming system for rotating the pin carrier with respect to the inner pin. However, other suitable mechanisms may be utilized which provide relative rotation of the pin carrier within the cylinder plug bore. By way of example, the comb  62  may be replaced by suitable gear rack which engages a set of gear teeth formed on the outer surface of the pin carrier for providing relative rotation. Similarly, since the present invention contemplates relative rotation between the pin carrier and the inner pin, other suitable mechanisms may be provided which rotate the inner pin with respect to the pin carrier. Likewise, the present invention has been illustrated as a five pin lock cylinder. However, one skilled in the art will readily recognize that the teachings of the present invention may be readily applied to provide any number of pin assemblies as dictated by the requirements of a given application.  
         [0029]     Accordingly, the description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.