Abstract:
A removable core cylinder assembly utilizes a plurality of modular parts to create a key-removable interchangeable core which will fit all existing interchangeable core locks of this kind. The removable core cylinder assembly includes accessories of a removable face plate which covers an axial recess in the cylinder shell for the locking tab and provides shelter to the head of the cylinder plug, and which is protected from removal from the cylinder shell by two stepped portions of the cylinder plug; and a key which includes a stop at the end of the tip of the key blade.

Description:
This is a continuation of application Ser. No. 09/122,083 filed Jul. 24, 1998, now U.S. Pat. No. 6,079,240, the disclosure of which is incorporated herein by reference. 
    
    
     The present invention relates to a modular type removable core cylinder assembly with locking tab (locking sleeve) having the same number of pin chambers as the cylinder shell and the cylinder plug, and which utilizes a plurality of modular parts to create a key-removable interchangeable core which will fit all existing interchangeable core locks of this kind. 
     BACKGROUND OF THE INVENTION 
     Conventional removable core cylinders are removable from a lock housing under the control of a control key for removing and e.g., replacing, the core. An operating key, or master key, is used to operate the lock in its normal condition and does not affect the removability of the core. Conventional removable cores utilize conventional pin tumblers which are evenly spaced in a single row along the length of the key barrel, which make removable cores subject to “picking” and thus, limiting the security they can afford. Conventional removable core cylinders are also more subject to security violations with unauthorized duplicated control keys. 
     Key-removable, interchangeable cores permit unskilled persons to rekey locks (i.e., block-out existing locks) without opening the door or removing the lock from the door. The cylinder is removed from the lock housing through the use of a control key, and a different interchangeable core cylinder of the same manufacturer can then be inserted into the lock housing, whereby the user can quickly and easily change a lock or locks without calling a locksmith. 
     Interchangeable cores are pinned for release from their housings by a single control key. The control key is actually a “top” master key whose sole function is limited to operation of the locking tab which retains the core in the lock housing. Interchangeable core control keys are not visually distinguishable from other keys in the system. Typically, the core is also pinned to one or more master keys and to a tenant key. Such a system usually requires three or four pin segments in each pin column; an arrangement which offers very limited pick-resistance. 
     Key-removable, interchangeable cores are manufactured by most American lockmakers. However, core interchangeability is usually limited to the housings of a single manufacturer. 
     High security locks include at least two mutually independent lock systems and are manipulated by different codes on one and the same key. The blade of the key to the system lock has a first, conventional code which coacts with the pin tumblers in the cylinder. 
     One of the high security features is the use of an independent locking mechanism on the side of the key—a sidebar—which is mounted in the radially outer part of the plug and which coacts with a row of side tumblers positioned laterally in the cylinder plug. The side bar prevents the cylinder from operating, should the top pins be “picked”. The side bar also provides the system owner with an exclusive key that is controlled by the factory. 
     The side tumblers in the sidebar are manipulated by a code provided on a side-part of the key, which when the key is inserted into the lock, engages a region of the side tumblers. When the correct key is inserted, the first-mentioned tumblers form a dividing plane between the cylinder plug and the cylinder shell and the side tumblers are moved to positions in which a radially and inwardly directed control part on the sidebar is enabled to engage waisted portions on the tumblers, such that the sidebar will move into the plug against the action of a spring force as the plug is rotated by means of the key. 
     Examples of sidebars used in conventional removable core cylinder assemblies, are disclosed in Widen (U.S. Pat. No. 4,356,713), Cox (U.S. Pat. No. 5,209,087), and Oliver (U.S. Pat. No. 3,298,211, Re. 31,910). 
     Although no standardization exists with respect to all manufacturers of removable cores, there have been some improvements in the prior art with respect to standardization of face plates which cover one end of the cylinder shells, such as that described in Best (U.S. Pat. No. 1,575,092). 
     Removable core cylinders with locking tabs (locking or control sleeves) having the same number of pin chambers as the cylinder shell and cylinder plug, and having a face plate permanently assembled to the front of the cylinder shell, and manufactured by Arrow, Best, Falcon, KSP, Medeco, and others, have been standardized. This subset of removable cores is called interchangeable cores. The majority of lock manufacturers make interchangeable core locks which accept interchangeable core cylinders of different manufacturers. 
     As an example of the prior art standardized interchangeable core cylinder assemblies, FIG. 1 discloses a FIG.  8 -shaped outer cylinder shell  1 , permanently assembled with a face plate  12  to cover the axial recess provided for the locking tab  3  and to create a bearing surface for the head of the cylinder plug  4 , a control sleeve  2  having the locking tab  3  formed thereon fitted in the cylinder shell and which also serves as a housing for the cylinder plug  4 , a rotatable key barrel or plug  4  which is fitted in the sleeve  2 , and a key stop disc or retainer  5 , which is similar to that described in Sussina (U.S. Pat. No. 5,176,015, Re. 35,518), and also Russell et al (U.S. Pat. No. 3,298,211), and Juang (U.S. Pat. No. 5,507,163). The control key  6  has a stop  13  and cannot be withdrawn from the core unless the locking tab  3  is in the extended (locking) position. The pin stacks  7  in the removable core cylinder lock assembly  8  include bottom pins  9  which are radially adjusted within the bores  10  by corresponding bittings  11  cut in the top edge of the key  6 . 
     As can be seen from the prior art in FIG. 1, the locking tab  3  is integrally formed with the control sleeve  2 , which means that the outer cylinder shell  1 , in order to provide for the sleeve  2 , has thin walls that are subject to deformation. 
     Further, another problem in the prior art is that, although the sidebar concept is used in removable core cylinder locks to provide greater security, standardized interchangeable cores have no room for the sidebars—thus limiting the convenience of using an interchangeable core. 
     Further, permanent assembly of the cylinder shell and the face plate, thin walls of the cylinder shell and ultra thin walls of the control sleeve forces the manufacturers to sell interchangeable cores only as one complete assembly. This leads to duplication in inventory based on finish and keyway, which add to distributors inventory costs. 
     Accordingly, there is no existing interchangeable core cylinder which has modular parts which can be purchased separately and the core built to an end-user&#39;s needs, wherein the modular elements are independently sturdy, and wherein the interchangeable core can provide the greater security of a sidebar feature. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a modular type removable core cylinder assembly with locking tab having the same number of pin chambers as the cylinder shell and the cylinder plug, and which utilizes a plurality of modular parts to create a key-removable interchangeable core which will fit all existing interchangeable core locks of this kind. 
     The removable core cylinder assembly according to a first embodiment of the present invention includes a cylinder shell having an axial bore formed therein, the axial bore having an axial recess formed along an axial length of the axial bore; a cylinder plug rotatably mounted within the cylinder shell and having two stepped portions at the front end thereof, wherein the second stepped portion has a smaller outer diameter and uses the front of the cylinder shell as a bearing surface; a locking tab seated within the axial recess of the cylinder shell, which locks the interchangeable core in the lock housing; a removable face plate which covers the axial recess in the cylinder shell for the locking tab, and provides shelter to the head (front end) of the cylinder plug; and a retainer which holds all the parts together and provides the stop for the key. 
     The provision of the novel locking tab, instead of a control sleeve with an integral locking tab, wherein the sleeve has thin walls which can deform, means that the walls of the cylinder shell of the present invention can be made thicker. 
     The modular design of the present invention allows more flexibility and cost savings in the production process, and yields a much stronger core in that, unlike other interchangeable cores, each modular element is independently sturdy. 
     The modular design of the present invention also saves distributors inventory costs, since the parts can be purchased separately and the core built according to the end-user&#39;s needs. There is no longer a need for a permanent assembly for each interchangeable core. Further, the modular new removable core cylinder assembly of the present invention will fit all existing interchangeable core locks of this kind. 
     The removable core cylinder lock assembly also features a novel high security option. One of the modules, the face plate, can be conventionally made or manufactured as drill resistant. The drill resistant face plate will meet high security core cylinder requirements with the addition of hardened steel pins. 
     Further, in the conventional interchangeable core cylinders, a permanent assembly of the face plate and cylinder shell was required when the face plate was inserted, and machining took place after this assembly. This machining was required to provide the bearing surface for the head of the cylinder plug. 
     In the present invention, the face plate is able to be machined and finished separately, prior to assembly, because the bearing surface for the cylinder plug is provided by the cylinder shell. 
     The removable core cylinder assembly according to a second embodiment of the present invention includes a cylinder plug rotatably mounted within the cylinder shell and having a sidebar projecting from an opening in an outer peripheral surface of the cylinder plug; wherein the cylinder shell has an opening in the axial bore for accommodating the sidebar; and a locking tab disposed in the cylinder shell, which locks the interchangeable core cylinder within the lock housing. 
     In the present invention, a sidebar can be used in the interchangeable core cylinder, by drilling one of the blind bores in the cylinder plug to accommodate the tail piece, which connects the core to a lock, shorter than the other (or drilling both blind bores shorter). The side bar prevents the cylinder from operating, should the top pins be “picked”. The side bar also provides the system owner with an exclusive key that is controlled by the factory—an important security feature. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings, wherein: 
     FIG. 1 shows a prior art interchangeable core assembly. 
     FIG. 2 shows an exploded view of the modular removable core cylinder assembly according to the present invention. 
     FIG. 3 shows a side elevational view of the cylinder shell showing the slot to receive the sidebar. 
     FIG. 4 shows a top plan view of the cylinder shell. 
     FIG. 5 shows a front elevational view of a cylinder plug. 
     FIG. 6 shows a sectional view taken from line  6 — 6  at FIG.  5 . 
     FIG. 7 shows a rear elevation of the view shown in FIG.  5 . 
     FIG. 8 shows a sectional view taken from line  8 — 8  at FIG. 7, showing the bores for the tailpiece (keyway not shown). 
     FIG. 9 shows a front elevational view of the cylinder shell with the locking tab in place. 
     FIG. 10 shows a front elevational view of the sidebar with the side tumbler pins in phantom lines. 
     FIG. 11 shows a rear elevation of the face plate with a hardened metal pin or bar at the side. 
     FIG. 12 shows a sectional view taken on line  12 — 12  at FIG. 11 showing the recessed portion. 
     FIG. 13 shows a side elevational view of the cylinder shell showing an opening to receive the locking tab having a central rectangular projection. 
     FIG. 14 shows a front elevational view of a locking tab with a central rectangular projection. 
     FIG. 15 shows a side elevational view of the locking tab with a central rectangular projection. 
     FIG. 16 shows a front elevational view of a locking tab with an extended rectangular projection. 
     FIG. 17 shows a side elevational view of the locking tab with the extended rectangular projection. 
     FIG. 18 shows a side elevational view of the is cylinder shell showing an opening to receive the locking tab with the extended rectangular projection. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A completed assembly of the first embodiment of the modular removable core cylinder assembly  20  of the present invention is described as follows, and is shown in FIG.  2 . The same reference numerals as those shown above represent the same elements. 
     The removable core cylinder assembly  20 , as depicted in FIG. 2, includes a removable core cylinder shell  21 , a cylinder plug  22  with a sidebar  23 , a locking tab  24 , a face plate  25 , and a retainer  26 . 
     The removable core cylinder shell  21  has a cylindrical body in the shape of a FIG. 8, with an  5  axial bore  27  formed therein. The cylinder shell  21  has an upper portion  28  which includes a plurality of axially-spaced radially-extending pinholes  29  for receiving pin stacks  7  (see FIGS.  1  and  4 ). Three small holes  30  are provided at a head portion of the cylinder shell  21  around the pinhole  29  closest to the front face  31  of the cylinder shell  21 , for the disposition of hardened pins (not shown), which are provided during assembly to provide drill resistance for the core assembly  20 . 
     The lower portion  32  of the cylinder shell  21  has a plurality of pin knockout holes  33  through which a tool is introduced to forcibly remove tumblers from the core assembly prior to rekeying. 
     The cylinder shell  21  includes a recess  54  in its upper portion (see FIGS. 2 and 9) which runs the axial length of the axial bore  27 , in which the locking tab  24  is seated (described later). 
     The cylinder plug  22  is mounted in the axial bore  27  in the lower portion of the cylinder shell  21  for rotation. The cylinder plug  22  includes a keyway  34  and a plurality of axially-spaced, radially-extending pinholes  35  communicating with the keyway  34 , each pinhole  35  opening onto an outer surface of the plug  22 . The number of pinholes  35  in the cylinder plug  22  corresponds to the number of pinholes  29  in the upper portion of the cylinder shell  21 , and preferably, but not necessarily, numbers  6  to  7  pinholes (see FIG.  6 ). 
     The front portion of the cylinder plug  22  has a blind bore  53   a  and a bore  53   b  (see FIG. 5) for the insertion of three hardened pins (not shown) to strengthen the drill resistance of the front face of the cylinder plug  22 . 
     The front portion of the cylinder plug  22  also has a first stepped portion  46  and a second stepped portion  60 , wherein the second stepped portion  60  has a smaller outer diameter than the first stepped portion  46 , with both stepped portions preventing the face plate  25  from being removed when the cylinder plug  22  is in place. The shoulder of the second stepped portion  60  uses the front of the cylinder shell  21  as a bearing surface. 
     The cylinder plug  22  includes two longitudinally extending blind bores  36 ,  37  (see FIGS. 7 and 8) bored parallel to the keyway  34  from the rear portion  36  of the barrel of the cylinder plug  22 , which engage with corresponding prongs of a tailpiece (not shown), all of which are rotatably disposed in the cylinder shell  21 , to operate the lock mechanism as the key turns. 
     A locking tab  24  having a curved tab body is provided to lock the removable core in the lock housing (see FIGS.  14 - 17 ). 
     The locking tab  24  also has the same number of pinholes  40  as that of the cylinder plug  22  and cylinder shell  21 , and has a rectangular projection  41   a  or  41   b  (see FIGS. 14 and 16) on one side of the tab body  24 , and a plurality of tooth-like projections  42  on the other side of the tab body  24  (see FIGS.  14 - 17 ). 
     When the locking tab  24  is disposed in the recess  54  of the axial bore  27 , the rectangular projection of the tab body  24 , which is preferably either an extended rectangular projection (see FIGS.  16  and  17 ), or more preferably, a central rectangular projection (see FIGS.  14  and  15 ), according to which embodiment is being used, is disposed in either the opening  57   a  (see FIG. 13) or the opening  57   b  (see FIG.  18 ), respectively, of the cylinder shell  21 . 
     A face plate  25  is provided to protect the locking tab  24 , and is inserted over the cylinder shell  21  at the front face  31  (see FIG.  11 ). The face plate  25  has a ring portion  43  and a solid portion  44 . The ring portion  43  has an inner stepped portion  45  which engages with the first stepped portion  46  of the front portion of the cylinder plug  22 . The solid portion  44  has a recessed portion (i.e. dovetail slot)  47  which slidably engages with the raised projection  48  of the cylinder shell  21  at the front face  31  of the upper portion  28 . The slotted recess  49  disposed between the ring portion  43  and the recessed portion  47 , is provided for the disposition of a hardened pin or bar  49 ′ which provides drill resistance for the removable core assembly  20 . 
     A substantially U-shaped retainer  26  with arms  50 , is provided as a key stop, and also to retain the cylinder plug  22  in the core assembly. The retainer arms  50  slide into the slotted portions  51  (see FIG. 6) on either side of the end face of the rear portion of the cylinder plug  22 , when the plug  22  is inserted in the cylinder shell  21 . 
     An operating key  52  is provided with a stop  13  at the end of the tip of the key blade. When the operating key  52  is inserted in the keyway  34  at the front portion of the plug  22 , the operating key  52  aligns the divisions between selected pin segments to coincide at the cylinder plug barrel periphery. The cylinder plug  22  interfaces with the connecting elements (not shown) which extend or withdraw a lock bolt (not shown) as the key turns. 
     According to a second embodiment of the present invention, an optional sidebar  23  is disposed within the plug  22 , by making one bore  36  shorter than the second bore  37 . The sidebar  23  projects through an opening  39  of the cylinder plug  22  (see FIG.  2 ), and when inserted in the cylinder shell  21 , the sidebar  23  projects through sidebar opening  38  (see FIG. 2) in the cylinder shell  21 . Each side tumbler pin has a groove to accept the sidebar  23 . The sidebar  23  is coded, so the grooves  56  of the sidebar  23  are disposed in different places (see FIG.  10 ). The cuts  57  in the key blade of the operating key  52  match the sidebar  23 . If the cuts  57  in the key  52  do not match the sidebar  23 , it protrudes from the opening  38  in the cylinder shell  21  to prevent the cylinder plug  22  from turning, even if the key  52  has the right cuts  58  in the top portion of the key blade. 
     The removable core cylinder lock assembly is assembled as follows. 
     The locking tab  24  is axially inserted into the cylinder shell  21 , such that the outer curved face of the locking tab body  24  rests on the floor of the inner recess  54 , the rectangular projection  41 a or  41 b of the locking tab  24  is inserted through the opening  25   57   a  or  57   b  of the cylinder shell  21 , and the tooth-like projections  42  of the locking tab  24  are inserted into the slots  59  disposed in the axial crease of the cylinder shell  21 . The pinholes  40  in the locking tab  24  align with the pinholes  29  in the upper portion  28  of the cylinder shell  21 . Note that the locking tab  24  has the same number of pinholes  40  as that of the pinholes  35  in the cylinder plug  22 , and that of the pinholes  29  in the cylinder shell  21 . Although the locking tab  24  fits in the recess  54 , there can be some play between the locking tab  24  and the side walls of the recess  54 , which allow for rotation of the locking tab  24  together with the cylinder plug  22 , when the control key is introduced. 
     The face plate  25  is then attached to the cylinder shell  21  by sliding the face plate  25  with its recessed portion  47  in contact with the front face  31  of the cylinder shell  21 , in a direction vertical to the front face  31  of the cylinder shell  21 , such that the raised projection  48  of the cylinder shell  21  slidably engages with the recessed portion  47  of the face plate  25 . 
     The cylinder plug  22  is then inserted into the axial bore  27  of the cylinder shell  21  at the front portion through the opening  45  of the face plate  25 , such that the pinholes  35  of the cylinder plug  22  align with the pinholes  40  of the locking tab  24 , and the pinholes  29  of the cylinder shell  21  and the second step  60  rests on the front portion of the cylinder shell  21 . The insertion of the cylinder plug  22  into the cylinder shell  21  is halted at the front portion by the second stepped portion  60 , and both the first stepped portion  46  and the second stepped portion  60  of the cylinder plug  22  are seated in the inner stepped portion  45  of the ring portion  43  of the face plate  25 , preventing the face plate from being removed. When the cylinder plug  22  is inserted in the cylinder shell  21  to form the cylinder core, the first and second bore openings  36 ,  37  are slightly tilted from the horizontal plane (see FIG.  7 ), and the slotted grooves  51  in the cylinder plug  22  protrude from the rear portion of the cylinder shell  21 . 
     The substantially U-shaped retainer  26  is then inserted with its arms  50  into the slotted portions  51  of the cylinder plug  22  which protrude from the cylinder shell  21  at the rear portion of the shell  21 . The retainer  26  holds the cylinder plug  22  in place within the cylinder core. 
     In operation, the cylinder plug  22  is rotatable in the cylinder shell  21 , and when the operating key  52  is inserted into the cylinder plug  22 , the cylinder plug  22  turns inside the cylinder shell  21  to release the lock. 
     If the sidebar  23  option is used, when the cylinder plug  22  rotates within the cylinder shell  21 , the sidebar  23  is released from the opening  38 , and pushed into opening  39 . 
     It is contemplated that numerous modifications may be made to the apparatus and procedure of the invention without departing from the spirit and scope of the invention as defined in the following claims.