Internal tumbler lock key change system
BACKGROUND OF THE INVENTION 
     In the prior art tumbler pin cylinder locks have been adapted to be changed for use with different keys. These kinds of locks have been particularly adaptable for hotels, apartments and office buildings where it is desirable to change the lock for use with a different key. 
     In these prior locks it was usually necessary to remove the cylinder from the door to make the changes and, in addition, tools were required to be inserted into the cylinders to make the key changes possible. 
     There have been other changeable locks which could be changed in place, but they also required a tool to be used from externally of the lock. 
     The present invention has eliminated the requirement for removal of the lock cylinders from the doors and, further, has eliminated the need for the use of an external tool. 
     SUMMARY OF THE INVENTION 
     The present invention provides means by which an auxiliary row of reserve master wafers are arranged in alignment with and angularly offset from a row of axially aligned locking bores. 
     The invention functions with the use of a six-pin changing key in a lock which is normally operated with a five-pin key, for example. It is only with the employment of a predetermined changing key that the changes can be made. 
     In accordance with the invention, more than a million key variations are possible in five-pin tumbler locks, utilizing five bores containing master wafers of various thicknesses. 
     Accordingly, it is an object of the invention to provide an improved tumbler lock key change system with substantially unlimited variations. 
     It is another object of the invention to provide a tumbler lock having a key change system in which predetermined keys make the combination changes. 
     It is still another object of the invention to provide a tumbler lock, as described in the previous paragraphs, in which the key changes are made entirely internally within the lock and no tools are required. 
     It is a further object of the invention to provide a tumbler lock in which operating keys can be changed without removing the cylinder from the door. 
     It is a still further object of the invention to provide a tumbler lock, as described in the previous paragraphs, in which an operating key cannot make the key changes. 
     It is another object of the invention to provide a tumbler lock having auxiliary bores containing master wafers, which when the plug has been rotated to be aligned with the auxiliary bores, only a proper predetermined changing key is operable to return the plug to be in alignment with the locking bores to effect an operating key change. 
     It is still another object of the invention to provide a tumbler lock, as described in the preceding paragraphs, in which the rotation of the plug between alignment with the locking bores and the auxiliary bores is precisely limited. 
     It is a further object of the invention to provide a tumbler lock, as described in the preceding paragraphs, in which the bore in a shutter operated by the changing key is smaller than the locking bores. 
     It is a still further object of the invention to provide a tumbler lock, as described in the previous paragraphs, in which clearance in the housing cylinder is provided for rotation of the shutter during the rekeying operation and which permits the smaller bore in the shutter to be used by holding means to retain the tumblers in the respective bores when the changing key is removed during the key changing operation. 
     Further objects and advantages of the invention may be brought out in the following part of the specification wherein small details have been described for the competence of disclosure, without intending to limit the scope of the invention which is set forth in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the accompanying drawings, which are for illustrative purposes: 
     FIG. 1 is a perspective view of a pin tumbler lock; 
     FIG. 2 is an exploded view illustrating a plug, cylinder and shutter in a pin tumbler lock, according to the invention; 
     FIG. 3 is a side elevational, partially cross-sectional view of the lock in FIG. 2, operable by a five-pin key and adapted to employ a six-pin key as a changing key; 
     FIG. 4 is a cross-sectional view illustrating structure for use in the key changing operation, taken along the lines 4--4 in FIG. 3; 
     FIG. 5 is a fragmentary cross-sectional view illustrating the use of a changing key; and 
     FIG. 6 is a cross-sectional view illustrating a normal locking-unlocking position of the lock, taken along the lines 6--6 of FIG. 3. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring again to the drawings, there is shown in FIGS. 1-3 a pin tumbler cylinder lock, generally designated as 10, having a generally cylindrical locking and unlocking plug 12, a cylinder or housing 14, and a cylindrical shutter sleeve 16, the plug being adapted to rotate within the shutter during normal locking operations and being adapted to rotate with the shutter within the cylinder during key changing operations. 
     As shown in FIG. 3, the cylinder 14 is threadedly engaged within a lock frame 15, for example, adapted to be secured within a lock body within a door, and secured to the inner end of the plug by screws 17 is a bolt throwing or latch releasing cam 19 which projects from and turns with the plug to lock or unlock the latch or bolt. 
     As shown in FIGS. 2-6, the cylinder, the shutter, and the plug have a row of five axially aligned cylindrical locking bores 18, 20 and 22, respectively. Within the plug, radially and axially aligned with the five locking bores, is a key slot 26. The locking bores in the cylinder extend from the lower end thereof, as shown in FIG. 3, and terminate at their upper ends in small diameter portions 30 so that the bores may be loaded from their lower ends. The shutter normally closes the lower ends of the housing bores. 
     Within each locking bore is a spring 32 in abutment with a conical surface 34 in the upper end of the bore. At the lower end of the springs are cylindrical top tumbler pins 38 slidably fitted within the bores and adapted to be moved upwardly toward the springs by a key, and adapted to be moved downwardly in the cylindrical shutter and plug bores 20 and 22, respectively, when a key is not in the slot. Each top tumbler pin 38 is generally made to be of the same length. 
     At the lower ends of the locking bores are five bottom, cylindrical, tumbler pins 42, 44, 46, 48 and 50, having convex ends and when a key is not in the slot their lower ends rest at the bottoms 56 of the plug bores 22 where they are held by the force of the springs 32, as indicated in FIG. 3. According to the operating key design, the bottom tumbler pins are of various lengths and, further, according to the operating key design, master wafer pins, as 60, 62 and 66, are inserted between the top tumbler pins and the bottom tumbler pins; the top, master and bottom pins being biased together by the springs 32. The master wafers may be of varying thickness or of the same thicknesses and varied in number, as shown at 60, 62 and 66. In the cases of bottom tumbler pins 46 and 48 of different lengths, according to the specific key design no master wafer pins are used in their locking bores. 
     As shown in FIGS. 3 and 6, an operating key 70 is in the slot 26 in operating locking and unlocking position. As shown in FIG. 6, the key has a lateral configuration on both sides 72 and 74 adapted to enter the slot 26 axially. 
     On the upper edge of the five-pin key, for example, are predetermined high and low pin facing contact surfaces 80, 82, 84, 86 and 88. These surfaces engage the lower ends of the bottom tumbler pins 42, 44, 46, 48 and 50, respectively, so as to form a break line 92 between wafers and/or pins just inwardly of the cylindrical wall of the shutter so that rotation of the key will permit rotation of the plug 12 within the shutter 16 to lock or unlock the lock, rotating the cam 19. The ends of any of the cylindrical pins or wafers adapted to form a break line surface are generally flat and fitted for precise operation. If chamfered edges are used, the lock operation is generally not as precise. 
     In axial alignment with the row of five locking bores is a sixth bore 100 within the housing, having therein a spring 32, and in a biasing relationship at the lower end of the spring is a first shutter holding pin 102, as best seen in FIGS. 3-5. The shutter holding pin 102 has a small diameter portion 104 terminating in a conical point 106. In FIGS. 3 and 4 the small diameter portion 104 is biased into a sixth shutter bore 108, smaller in diameter than the five bores 20, and the shoulder on the pin 102 outwardly of the small diameter portion rests on the outer cylindrical surface of the shutter. 
     In radial or transverse alignment with the shutter holding pin bore 108 is an annular groove 112 in the outer surface of the plug, the conical end 106 extending into the groove. Thus, when the shutter holding pin is extending through the shutter bore 108, the shutter is locked against rotation for operation with a five-pin key, as 70. Extending inwardly from the groove 112 in radial alignment with the bore 100, and in axial row alignment with the locking bores, is a shutter releasing and rotating pin 122. As shown in FIGS. 3 and 4, when a five-pin key is in the plug, the convex bottom of the pin 122 rests on the bottom of the plug bore 120. The pin 122 has an upper reduced diameter portion 124, terminating in a conical end 126, the reduced portion 124 being adapted to fit within the shutter bore 108. 
     As shown in FIGS. 3 and 4, the pin 102 is extending into a cutaway cavity 127 in the housing, radially outwardly of and in alignment with groove 112. This cavity provides clearance for the rotation of the end 126 of the pin 122 when the end is extending into the shutter bore 108 and the plug and shutter are rotated during the lock-key changing operation, about to be described. 
     As shown in FIG. 5, there is a six-pin lock changing key 132, corresponding to the operating key 70, having an additional sixth upper edge operating contact or bit surface 134. 
     The changing key 132 is otherwise identical to the operating key 70 except that its five bit or contacting surfaces, corresponding to surfaces 80, 82, 84, 86 and 88, are regularly higher, as 88A, in FIG. 5, corresponding to 88 in FIG. 3, to raise the break line, as 92A, of all the pins to be just outwardly of the shutter wall. 
     After the operating key has been removed, the changing key 132 is inserted into the slot for the purpose of changing the lock for operation by a new operating key. The key surface 134 moves the pin 122 in the plug upwardly against the pin 102, moving its small diameter portion out of the shutter bore 108 and moving the small diameter portion 124 therein, FIG. 5. The five contacting surfaces raise wafer pins 60, 62, 66 and the tumbler pins 46 and 48 into the shutter bores to form the new break line 92A, as illustrated for the wafer pin 66 in FIG. 5. In this situation the changing key 132 is adapted to rotate the plug and the shutter within the housing, the conical end 126 being adapted to rotate in the cavity 127. As shown in FIGS. 4 and 6, angularly offset from the locking bores and the shutter holding pin bore 100 in the housing are a row of five axially aligned auxiliary or reserve master pin wafer bores 140 in alignment with a sixth bore 142 which is a second shutter holding pin bore containing a spring 144 and a second shutter holding pin 146, having a small diameter portion 148 and a conical end 150. The bores 140 are in transverse alignment with the respective five locking bores 18 and the bore 142 is in alignment with the bore 100, so that precise rotation of the plug and shutter will radially align their locking bores with respective auxiliary bores. During normal locking operation, the end 150 is in contact with the outer surface of the stationary shutter 16, as shown in FIG. 4. 
     In order that the rotation of the plug and shutter be precise with respect to the locking and auxiliary bores, as shown in FIGS. 2 and 4, a slot 156 extends through the surface of the shutter in alignment with the groove 112. The slot has about the same width as the diameter of the shutter bore 108. Threadedly engaged within a housing bore 160, FIG. 4, is a set screw 162 having a cylindrical end 164 engaged within the slot 156 and extending into the groove 112. The upper end of the pin 164 is in abutment with the upper end of the slot in which position the pin 102 is in locking position to hold the shutter against rotation. 
     When the six-pin key 132 is turned to rotate the plug and shutter counterclockwise, having moved the small diameter portion 124 of the pin 122 into the shutter bore 108, the end 126 of the pin 122 rotates in the cavity 127 to engage the conical end 150 of the second shutter holding pin, moving it outwardly against the force of the spring 144. The limit of this rotation is determined by the lower end of the slot 156 which is then in contact with the lower end of the pin 164. At this point the shutter and plug bores are respectively radially aligned with auxiliary bores. When the changing key is then removed, the end 150 of the pin 146 moves into the shutter bore 108 to engage the small diameter portion 148 therewith and to lock the pin 146 in the key changing position. 
     During the rotation of the shutter 16 and plug 12 by the changing key, as shown in FIG. 5, the raised bottom tumbler pin 50 and the master wafer pin 66 remain radially in place with respect to the shutter and the changing key. The same is true of the other raised bottom tumbler pins 42, 44, 46 and 48 and their master wafer pins 60 and 62 within the shutter and plug. 
     In each of the five reserve master wafer bores 140, illustrated in FIG. 6, there is a spring 170 extending within a top reserve pin 172 and having at its lower end one or more master wafer reserve pins 174. Thus, when the first changing key 132 is removed from the slot, a second six-pin changing key is inserted into the slot and the wafers 174 in the various five reserve bores will be moved upwardly or downwardly in the bores 140 and the respective shutter and plug bores in accordance with the shape of the key, so that a break line 92A outwardly of the shutter bores 20 is formed to permit rotation by a new operating key. The master reserve wafer pins 174 are of the proper size so that any predetermined new key will position the wafers 174 to form a break line among them for each auxiliary bore just outwardly of the cylindrical walls of the bores 20 of the shutter. 
     Thus, the new six-pin changing key is adapted to rotate the plug and shutter clockwise back to the position shown in FIG. 4, the pin 122 remaining within the shutter bore 108. When the six-pin changing key is removed, the spring in the housing holding pin bore 100 moves the pin 102 back into the oerating locking position, and the pin 122 drops down into the position as shown in FIGS. 3 and 4. At this point a new operating key, corresponding to the structure of changing key but having lower contacting or bit surfaces, can then be inserted into the slot to operate the lock. 
     As may be seen, a multiplicity of key changes can be made depending upon the thickness and numbers of the wafers 174 in the auxiliary bores 140. In each case the key must be adapted to position and number the wafers to form a break line so as to permit the rotation of the plug and shutter back to the operating position and to permit rotation of the plug by the operating key while the shutter remains stationary. 
     The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangements hereinbefore described being merely by way of example. I do not wish to be restricted to the specific forms shown or uses mentioned except as defined in the accompanying claims, wherein various portions have been separated for clarity of reading and not for emphasis.