Shearable lock assembly and method of manufacture

Information

  • Patent Grant
  • 6263713
  • Patent Number
    6,263,713
  • Date Filed
    Wednesday, March 3, 1999
    25 years ago
  • Date Issued
    Tuesday, July 24, 2001
    23 years ago
Abstract
A lock and a method for manufacturing the lock. The lock comprises a shell having an interior cavity, a plug received in the interior cavity rotatably and axially slidably therein and defining a keyway configured to receive a preselected key, and a tumbler insertable in the plug. The tumbler has a plug portion disposed at a first axial location within the plug and resiliently biased outwardly toward a locked radial position and associated with the keyway such that the preselected key inserted in the keyway locates the tumbler in an unlock position and a shell portion disposed at a second axial location in the shell wherein the second axial location is axially spaced from the first axial location. The shell, the plug and the tumblers are configured such that the tumblers are sheared between the plug and the shell when the plug and the shell are forced axially toward each other.
Description




BACKGROUND OF THE INVENTION




The present invention relates generally to cylinder locks having key operable tumblers. Cylinder locks have been widely used to secure doors and padlocks and in other applications. In certain applications, it is desirable that a single key fits a plurality of locks. For example in automotive applications, users may desire to have a single key that opens the doors, glove compartment and trunk that also operates the ignition. If one of the locks requires replacement at a later time, the replacement lock may require a new key for operation if the replacement lock is unable to be fitted to the original key.




U.S. Pat. No. 1,979,939 discloses a device and method for shearing projections of tumbler ends to fit a lock to a particular key. Spring loaded, wafer-like tumblers, having a length greater than the diameter of the plug of a lock, are inserted into the plug with the tumbler ends projecting axially beyond the plug. When a key is inserted in the keyway of the lock, the notches and cams on the blade of the key displace the tumblers and springs, projecting certain portions of the tumbler beyond the ends of the plug. A tool having two complementary cutters is used to shear the projected ends off the tumblers. When the key is removed and the plug is inserted in the shell, the springs are allowed to expand, forcing the tumblers to protrude into slots in the shell of the lock and preventing the rotation of the plug within the shell. As all of the tumblers are sheared together, a significant shearing force is required.




U.S. Pat. Nos. 5,697,239 and 5,735,153 disclose a method and apparatus for the manufacture of a pin tumbler cylinder lock with shearable assembly pins. The pins have a plurality of selectively weakened locations for an initial configuration of the lock corresponding to the shape of a notched key. The pins are biased radially into the plug of the lock by springs located in the lock shell. The pins can be sheared by the manufacturer or a locksmith, with the sheared portions of the pins functioning as the driver and the tumbler pins.




The disclosed methods and apparatus require the use of cutting tools or a significant shear force to fit the lock to a particular key. There is a need for a method of manufacture of a lock that provides greater case in keying or rekeying locks without comprising the security of the lock.




SUMMARY OF THE INVENTION




The present invention is related to a lock having a shell, a plug mounted in the shell and a plurality of tumblers that extend into the shell. The tumblers have a plurality of grooves notched on both ends such that when a key is inserted in the lock, the key lifts the tumblers according to the notches on the key, aligning the grooves on the tumblers. The shell and plug are forced axially toward each other shearing the tumblers along the aligned grooves to fit the lock to the key. The present invention is further directed to a shell and plug configuration that reduces the total shearing force required for shearing the tumblers and to a method of manufacturing a lock having shearable tumblers for a preselected key.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a cross-sectional view of the lock constructed according to the present invention prior to the shearing of the tumblers;





FIG. 2

is a cross-sectional view of the lock in

FIG. 1

along lines


2





2


;





FIG. 3

is a cross-sectional view of the lock in

FIG. 1

along lines


3





3


;





FIG. 4

is a side view of a two-sided notched key;





FIG. 5

is a front view of a tumbler of an embodiment of the present invention;





FIG. 6

is a side view of the tumbler of

FIG. 5

;





FIG. 7

is a front view of a retention tumbler of an embodiment of the present invention;





FIG. 8

is a side view of the retention tumbler of

FIG. 7

;





FIG. 9

is a top view of a retention sleeve constructed according to the present invention;





FIG. 10

is a cross-sectional view of the retention sleeve in

FIG. 9

along plane


10





10


;





FIG. 11

is a flowchart showing the steps of assembling the lock according to the present invention





FIG. 12

is a cross-sectional view similar to the lock in

FIG. 1

in which the tumblers have been sheared by relative axial movement between the shell and the plug;





FIG. 13

is a cross-sectional view of the lock in

FIG. 12

along plane


13





13


;





FIG. 14

is a cross-sectional view of the lock in

FIG. 12

along plane


14





14


;





FIG. 15

is a cross-sectional view of the lock in

FIG. 12

along line


15





15


;





FIG. 16

is a cross-sectional view of

FIG. 14

in an unlocked position;





FIG. 17

is the lock in

FIG. 16

in the locked position;





FIG. 18

is a front view of a tumbler of another embodiment;





FIG. 19

is a side view of the tumbler in

FIG. 18

;





FIG. 20

is an enlarged cross-sectional end view of an embodiment of the present invention with the tumbler of

FIG. 18

;





FIG. 21

is a side view of the lock of

FIG. 20

;





FIG. 22

is a cross-sectional view of a third embodiment of the present invention;





FIG. 23

is top view of a fourth embodiment of the present invention shown illustratively without a retention sleeve;





FIG. 24

is a cross-sectional view of the tumbler in

FIG. 23

shown with a retention sleeve;





FIG. 25

is a side-elevational view of an apparatus for holding the lock assembly when shearing tumblers; and





FIG. 26

is a cross-sectional view of the apparatus of

FIG. 25

along plane


26





26


.











DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring now to

FIG. 1

, lock


100


, as shown in a loading position, comprises a substantially cylindrical shell


102


having a shell interior cavity


104


. Shell


100


has seven shell passageways


106


extending radially between the exterior of the shell


102


and the shell interior cavity


104


. The shell


102


is preferably made of zinc, brass, plastic or other suitable materials.




A turnable cylindrical plug


108


is axially mountable for rotatable movement within the shell interior cavity


104


of the shell


102


. The plug


108


has a plug collar


110


located at one end of the plug


108


and a plug tail


112


disposed axially from the plug collar


110


on the other end of the plug


108


. The plug tail


112


is connectable to a latch that drives a bolt or other locking devices to lock or open a door or other movable member as disclosed in the art. The plug


108


has a keyhole


113


leading to a keyway


114


configured for receiving the blade


128


of a key


116


. Plug


108


has seven plug passageways


118


extending radially from the keyway


114


through the plug


108


and opening into the shell


102


. The plug


108


has an outer diameter


109


that is less than the inner diameter


111


of the interior cavity


104


of the shell


102


, creating a shearing zone


120


between the shell


102


and the plug


108


. In the loading position of the lock as shown in

FIG. 1

, plug passageways


118


extend across the keyway


114


and are initially aligned with shell passageways


106


for receiving shearable, wafer-like, tumblers


122


. The plug


108


is preferably made of a zinc, brass, plastic or other suitable materials.





FIG. 1

shows the preferred embodiment according to the present invention in a loading position in which the tumblers


122


are loaded in the plug and shell passageways


118


and


106


respectively of the plug


108


and shell


102


before being sheared therebetween. In

FIG. 1

, the shell


102


and the plug collar


110


define a gap


150


for allowing axial movement of the plug


108


relative to the shell


102


along the shearing zone


120


. The dimension of the gap


150


is selected to allow sufficient penetration of the plug


108


into the shell


102


when shearing the tumblers


122


. Preferably the gap is between 0.04 inches and 0.06 inches, and most preferably, the gap is about 0.05 inches.




A tubular retention sleeve


152


is manufactured to fit over the exterior of the shell


102


and is securable to the shell


102


by a retention sleeve crimp


154


engaging the exterior of the shell


102


, as shown in FIG.


1


. Preferably the retention sleeve crimp


154


is in one of the shell passageways


106


, but the sleeve may alternatively engage with another recessed portion of the shell


102


. Referring to

FIGS. 2

,


3


,


9


and


10


, the retention sleeve


152


has a set of first slots


156


and a set of second slots


158


extending therethrough that are alignable with the shell and plug passageways


106


and


118


. Preferably the first set of slots


156


and the second set of slots


158


are interposed axially in sequence and are angularly displaced from each other around the sleeve by a sleeve displacement angle


160


. Angularly displacing slots


156


and


158


allows the insertion of the tumblers


122


into the plug and shell passageways


106


and


118


in two groups such that the tumblers


122


are radially and resiliently biased from the plug in radially opposite directions, as described in greater details hereinafter. The slots


156


and


158


have a rectangular portion


159


shaped to receive the tumblers


122


and a circular portion


161


shaped to receive the springs


178


. Sleeve angle


160


is measured from the center of the rectangular portion


159


of the sleeve slot


156


to the center of the rectangular portion


159


of the sleeve slot


158


. Preferably, sleeve angle


160


is less than 180° such that the one set of slots


156


and


158


allows the insertion of the tumblers


122


into alternative plug and shell passageways


106


and


118


while the other passageways are closed by the sleeve


152


. Most preferably, sleeve angle


160


is about 135°. Preferably, the sleeve angle


160


is between 5° and 180°, or more preferably 90° to 150°.




Referring to

FIGS. 2 and 3

, the lock is shown in the loading position with the shell passageways


106


and plug passageways


118


aligned, and shearable tumblers


122


extending radially from one side of the plug


108


to the other and into the shell passageways


106


. Each shell passageway


106


has a first shell opening


162


that is preferably wider than a second shell opening


164


. Similarly, each plug passageway


118


has a first plug opening


166


that is wider than a second plug opening


168


. The first plug opening


166


meets the second opening


168


forming a spring seat


170


within the plug


108


.




In

FIG. 2

, the sleeve


152


openings


156


are aligned with alternate shell and plug passageways


106


and


118


marked as A for loading with tumblers


122


. In

FIG. 3

, on the other hand, sleeve


152


has been rotated to align openings


158


with alternate plug and shell passageways B for loading tumblers


122


.




Keys adaptable for cylinder locks are either one or two sided, i.e., having notches on one side or both sides of the blade of the key, respectively. A one-sided key usually has about five notch locations with about eight different depths of cuts associated with each notch location. In contrast, a two-sided key is notched on both sides and may use as many as ten notch locations with about five different cut depths associated with each notch location. An example of a use for a two-sided key is in automotive cylinder locks. The two-sided key, having greater number of notch locations, can accommodate the various applications associated with the car, such as the ignition, doors, trunk, and glove compartment. In addition, automotive cylinder locks provide multiple levels of security through the use of secondary keys that only allow access to selected applications, such as the valet key. Moreover, a lock cylinder for use with two-sided keys allows removal of the key from the cylinder in either locked or unlocked positions.




A key


116


, adaptable for use with the present invention, is shown in

FIG. 4

as having a plurality of notch locations


124


with each having various different cut depths


126


on opposite edges of the blade


128


of the key


116


. Key


116


, has ten notch locations


124


and five different cut depths


126


on opposite edges of the blade


128


of the key


116


, creating 9,765,623 usable keying combinations.




Each tumbler


122


has a key blade abutting portion


138


located in a center opening


136


, as shown in FIG.


5


. The opening


136


is cut out from the tumbler


122


and is shaped to receive the blade


128


of the key to interface with the key notches


124


. Finally, each tumbler


122


has a protuberance


139


protruding laterally therefrom to define a ledge


140


and an outer tumbler seat


141


. The tumblers


122


are made of a suitable material, such as brass. Multiple grooves


130


are preferably coined or stamped on the surface of the tumblers


122


, as shown in

FIGS. 5 and 6

. Each tumbler


122


is wafer shaped and has a thickness


129


and five weakened zones defined by notches or grooves


130


on each side of the tumbler to facilitate and localize their shearing. Also, the grooves are arcuate in this embodiment with a shape corresponding to the shape of the shearing zone


120


defined between the plug and the shells. The groove widths


132


and depths


134


are selected to reduce the axial shear force necessary for shearing the tumblers


122


when configuring the lock with a preselected key. During this configuring operation, an axial shearing force is applied to shear the tumblers


122


by axially shifting the plug


108


and shell


102


relative to each other.




The grooves


130


have a radius of curvature


135


, preferably between the radius of the interior cavity


104


and the outer radius of the plug


108


. Each of the grooves


130


has a groove width


132


, preferably ranging from about 0.0060-0.010 inches. The grooves are spaced at a radial distance


133


from each other. The radial distance


133


preferably corresponds to the distance between the available notch depths


126


at each notch location of the key


116


. Preferably, the radial distance


133


is between about 0.015-0.030 inches. Most preferably, the radial distance


133


is about 0.025 inches. However, distance


133


can be modified to accommodate different keying systems. The grooves have a depth


134


, as shown in

FIG. 6

, and the preferred groove depth


134


is about 0.012 inches. The series of grooves


130


is positioned on the tumblers


122


such that the grooves


130


are alignable with the shearing zone


120


between the shell


102


and the plug


108


by preselected keys with the appropriate combination of notch locations


124


and cut depths


126


, as shown in

FIGS. 1-3

. The number and placement of the grooves


130


preferably correspond to the available cut depths


126


of the key notches


124


, although additional grooves


130


can be employed.




The tumblers


122


have a relative torque strength which corresponds to the amount of rotative torque the tumbler


122


can resist when the plug


108


is forced rotationally in the shell


102


with the tumblers


122


in the locked position against the walls of the passageways. It is desirable to maximize the rotative torque strength of the tumblers


122


while minimizing the axial shearing force required for shearing the tumblers


122


in manufacturing a lock. Accordingly, the tumbler groove


130


portions of the tumblers


122


arc not so weakened such that another insertable key, one having the same keyway configuration as the preselected key but with a different notch cut, could be torqued by hand or by a tool to further shear the tumblers


122


prior to key or tool failure. In other words, the weakest part of the grooves


130


, or the center


131


, is preferably strong enough to resist a torque force to the tumblers


122


equal to the maximum rotative force that can be applied through the keyhole


113


by any key or key-like tool that can be inserted into the keyhole


113


. This minimizes compromise in security while the lock is in service.




Referring to

FIGS. 1-3

and


15


, the shell


102


defines a retention groove


142


with a rearwardly facing retention wall


144


adjacent to the interior cavity


104


. The retention groove


142


circumferentially abuts the interior cavity forming stops


171


at either end of the groove, best shown in FIG.


15


. The plug


108


defines a retention slot


146


extending radially from the keyway


114


into the plug


108


and opens into the interior cavity


104


. A retention tumbler


148


, as shown in

FIGS. 7 and 8

, and a retention spring


147


, as shown in

FIG. 15

, are insertable within the retention slot


146


. In

FIG. 1

, the retention tumbler


148


is in an inactive position and out of engagement with the retention groove


142


of the shell


102


. When moved to its active position upon axial shifting of the plug


104


toward the shell


102


from the loading position of

FIG. 1

to the operative position of

FIG. 12

, the retention tumbler


148


is axially biased by the spring


147


within the plug


108


to extend outwardly toward the shell retention groove


142


and is allowed to rotate freely against the retention wall


144


. In this position, the retention tumbler


148


prevents the extraction of the plug


104


from the shell


102


.




The retention tumbler


148


preferably has a greater thickness


149


and a greater strength than the shearable tumblers


122


. Instead of a separate retention tumbler


148


, a plurality of retention grooves


142


may be disposed in the shell passageways


106


to engage the outwardly biased tumblers


122


for retaining the plug


108


within the interior cavity


104


.




The shell


102


further defines shell locking channels


172


, shown in

FIGS. 16 and 17

, that extend radially from the interior cavity


104


of the shell


102


for receiving the tumblers


122


when the lock


100


is in its operative position of FIG.


12


. Locking channels


172


engages the plug portions


200


of the tumblers


122


to prevent rotation of the plug


108


in the interior cavity


104


of the shell


102


. The locking channels


172


are shown as diametrically opposed, or located at 180°, with respect to each other. In this arrangement, the plug


108


can be rotated 180° between the lock and unlock positions so that the key


116


may be removed. However, locking channels


172


may be disposed in the shell at an angle less than 180° with respect to each other, where less rotation of the plug


108


in the interior cavity


104


is desired. In addition, the shell may comprise only one locking channel


172


, which will allow the key


116


to be removed from the lock


100


only when it is in the locked position. This is desirable for high security uses where the lock is to remain locked unless an intended user is present with the key


116


.




In the assembly of the lock


100


, as described in the flow chart in

FIG. 11

, the retention tumbler


148


and retention spring


147


are inserted into retention slot


146


, at axial location X in

FIG. 1

, of plug


108


. The retention tumbler


148


is depressed against the retention spring


147


when the plug


108


is inserted within the interior cavity


104


of the shell


102


and remains depressed within the plug


108


by the inner wall of the shell inner cavity


104


during the loading of the tumblers


122


. The plug


108


is thereafter inserted into the interior cavity


104


of the shell


102


along a center axis


174


such that the shell passageways


106


and plug passageways


118


are aligned, and the gap


150


is created between the shell


102


and the collar


110


of the plug


108


. The shell passageways


106


are aligned with plug passageways


118


such that the first shell openings


162


are aligned with first plug opening


166


and the second shell opening


164


are aligned with second plug opening


168


at axial locations A, as shown in

FIGS. 2 and 3

.




Retention sleeve


152


is placed around the shell


102


in a first loading position in which the first slots


156


are aligned with first shell openings


162


and first plug openings


166


at location A and the second shell openings


164


and second plug openings


168


are covered. The first loading position exposes alternating shell passageways


106


and plug passageways


118


at axial locations A in FIG.


1


. Springs


178


are inserted into the exposed shell and plug passageways


106


and


118


through circular portions


161


of the first slots


156


with the springs


178


abutting the spring seats


170


, as shown in FIG.


2


. Tumblers


122


are then inserted into the exposed shell and plug passageways


106


and


118


through the rectangular portions


159


of the first slots


156


such that springs


178


are held between ledges


140


of the tumblers


122


and the spring seats


170


, for biasing the tumblers


122


radially outward from the plug


108


toward the shell


102


.




The retention sleeve


152


is then rotated about the center axis


174


by an angle


182


to a second loading position. In the second loading position, second slots


158


of the retention sleeve


152


are aligned with the remaining shell and plug passageways


106


and


118


, at locations B in FIG.


1


. In the second loading position, the sleeve


152


closes off the shell and plug passageways


106


and


118


at locations A. The rotational angle


182


is correlated to sleeve angle


160


such that rotating the sleeve


152


with the first slots


156


aligned with shell and plug passageways


106


and


118


at axial locations A about the center axis


174


by rotational angle


182


aligns the second slots


158


with shell and plug passageways


106


and


118


, as shown in FIG.


2


. Springs


178


and tumblers


122


are disposed within the exposed shell and plug passageways


106


and


118


at location B with springs


178


held between ledges


140


and spring seats


170


, for biasing the tumblers


122


radially outwardly from the plug


108


toward the shell


102


in a direction opposite the tumblers


122


at location A, as shown in FIG.


3


.

FIG. 1

shows the lock


100


in its loading position and

FIGS. 2 and 3

show the tumblers


122


in a pre-shearing position. The tumblers


122


in the shell and plug passageways


106


and


118


in the first locations A are interposed axially with tumblers


122


in the second locations B such that the tumblers are resiliently biased upwardly and downwardly by the springs


178


in a sequentially alternating fashion along the direction of the axis


174


.




The retention sleeve


152


is rotated a second rotational angle


190


, preferably about 45°, about the center axis


174


to a closed position in which both the slots


156


and


158


are out of alignment with all shell and plug passageways


106


and


118


. The retention sleeve


152


is then secured by the retention sleeve crimp


154


on the exterior of the shell


102


by crimping a portion of the sleeve material therein for retaining the tumblers


122


in the shell


102


, as shown in

FIG. 1

, or in one of the shell passageways


106


, as shown in FIG.


12


. In the closed position, the retention sleeve


152


closes off the shell passageways


106


from the exterior of the lock


100


.




In this loaded position, the lock is now ready to be fitted to the preselected key


116


. A key adaptable for use with the present invention is the two-sided key


116


, as shown in FIG.


4


. Key


116


is inserted within the keyway


114


of the lock


100


through key hole


113


. The sloped positions


193


, shown in

FIG. 4

, of the key blade


128


cam the tumblers


122


, through abutment with the upper edges


138


of the tumbler openings


136


in contact with the notches


124


. The tumblers


122


are resiliently biased in opposite directions against the key


116


by the springs


178


. The insertion of the key


116


retracts the tumblers


122


inwardly into the plug


108


to an unlocked position in which certain grooves


130


are aligned along the shearing zone


120


. Shell


102


and the plug


108


are then forced axially toward each other along the center axis


174


to complete the assembly of the lock


100


into the operative operation, as shown in FIG.


12


. As the plug


108


is forced toward the shell


102


, tumblers


122


are sheared along the aligned grooves


130


, and the gap


150


between the shell


102


and plug collar


110


is closed. The size of gap


150


is selected such that penetration of the plug


108


into the shell


102


is halted at the assembled operative position shown in

FIG. 12

, when the collar


110


contacts the proximal or front side


137


of the shell


102


. In the operative position, as shown in

FIG. 12

, the axial travel of the plug


108


into the shell


102


is restricted such that the shell passageways


106


are no longer aligned with plug passageways


118


. Forcing the plug


108


into the shell


102


completely shears the tumblers


122


into releasable or shell portions


198


and plug portions


200


. The shell portions


198


remain in the shell passageways


106


inside the retention sleeve


152


, and the plug portions


200


remain in the plug passageways


118


.




In the operative position of

FIG. 12

, the plug portions


200


of the tumblers


122


are out of alignment with the shell passageways


106


by a distance


197


, which is preferably greater than the thickness


129


of the tumblers


122


. Accordingly, when the plug


108


is rotated within the interior cavity


104


, the plug portions


200


of the tumblers


122


abut the interior cavity wall


231


between the passageways


106


preventing the tumblers


122


from catching the shell passageways


106


when the plug


108


is rotated within the interior cavity


114


, as shown in

FIGS. 13 and 14

. Preferably, the distance


197


is between 0.036 and 0.076 inches. Most preferably, the distance


197


is 0.056 inches.




As explained above, once the lock


100


is in the operative position, the retention tumbler


148


is biased radially outward into the retention groove


142


abutting the retention wall


144


to prevent extraction of the plug


108


from the shell


102


, as shown in FIG.


15


. The retention tumbler


148


is extended into the retention groove


142


, and the plug


108


is rotatable within the shell


102


with the retention tumbler


148


abutting the retention groove


142


preferably in contact with the retention wall


144


. Since the rotation of the retention tumbler


148


is restricted about the center axis


174


when the retention tumbler contacts either one of the two stops


171


, the rotation of the plug


108


within the interior cavity


104


is likewise restricted. Preferably the stops


171


in the retention groove


142


sufficiently restrict the rotation of the plug


108


within the interior cavity


104


such that the plug portion


200


is retained in an unlocked position by the interior cavity wall


231


of the interior cavity


104


and allow the lock


100


to rotate from the locked position to the unlock position, as described below with reference to the locking channels


172


. Preferably, the retention tumbler


148


and the retention groove


142


allow at least 90° of rotation of the plug


108


with respect to the shell


102


, and most preferably up to about 270°.




Referring to

FIG. 16

, when the lock is in use and the key


116


is inserted within the keyway of the lock


100


in the locked position, the notches


124


of the key


114


depresses the spring


178


to shift the plug portions


200


out of the locking channel


172


, shown at the left side of FIG.


16


. While the key


116


remains in keyway


114


, the plug


108


can rotate within the interior cavity


104


of the shell


102


, and at this state, the lock


100


is still unlocked. Once the key


116


is removed, as shown in

FIG. 17

, the spring


178


is relaxed thereby radially extending the plug portion


200


into the oppositely disposed locking channel


172


until the tumbler seats


141


abut the interior wall


231


, preventing rotation of plug


108


within the interior cavity


104


of the shell


102


, and at this state, the lock


100


is unlocked.




Once the lock


100


is in the operative position, the shell


102


, containing the tumbler shell portions


198


within the shell passageways


106


, and the sleeve


152


can be removed and replaced with another shell having only locking channels


172


without interfering with the operation of lock


100


. The removed shell maybe reused for fitting another key and plug. In order to replace the shell


102


with one having only locking channels


172


, the retention tumbler


148


can be pushed inwardly from the retention groove


142


, depressing the retention spring


147


and thus allowing extraction of the plug,


108


from the internal cavity


104


of the shell


102


. During extraction, the tumbler shell portions


198


will fall out of the shell passageways


106


. The retention sleeve


152


may then be removed, and the shell


102


can be reassembled with new tumblers


122


. Preferably, however the shell


102


and sleeve


152


are left in place.





FIGS. 18 and 19

, show a modified embodiment of the tumbler. Here, tumbler


300


has straight grooves


302


disposed on opposite ends of the tumbler


300


, forming weakened zones to facilitate and localize the shearing of the tumblers


300


. The multiple grooves


302


are preferably coined or stamped on the surface of the tumblers


300


. The entire tumbler


300


is preferably coined or stamped from a sheet of material in a single operation. The groove widths


306


and depths


308


are selected to reduce the shear force necessary for shearing the tumblers


300


while preserving sufficient strength in the unsheared groove portion of the tumblers


300


, as shown in FIG.


19


. Preferably, the bases


303


of the grooves


302


are sharp or have a small radius of about 0.002 inches. As shown in

FIGS. 20 and 21

, tumblers


300


are insertable into a lock


316


having a shearing zone


318


formed between shell


320


and plug


322


. The series of grooves


302


is positioned on the tumblers


300


such that the grooves


302


are alignable with the shearing zone


318


by a preselected key


116


. Preferably the plug


322


has plug passageways


324


with laterally straight edges


326


across the opening of the plug passageways


324


.





FIG. 22

shows a lock


400


that comprises a substantially cylindrical shell


402


that has a shell interior cavity


404


. As shown, shell


400


has seven shell passageways


406


extending radially from the exterior of the shell


402


to the interior cavity


404


. Plug


408


has seven plug passageways


418


extending radially from a keyway


414


across the plug


408


. The plug passageways


418


are alignable with shell passageways


406


for inserting shearable tumblers


422


.




Whereas the widths of the shell passageways in the previous embodiment were substantially equal to each other, the shell passageways


418


of lock


400


have different widths. The shell passageways


406


at axial locations C preferably have the smallest axial width


426


, which is preferably larger than the axial width of the preformed tumblers


422


by a width D


1


of about 0.001 inches. The shell passageways


406


at axial locations D preferably have a larger axial width


428


, which is larger than the axial width of the preformed tumblers


422


by a width D


2


of about 0.005 inches. The shell passageways


406


at axial locations E have a still larger axial width


430


, which is preferably larger than the axial width of the preformed tumblers


422


by a width D


3


of about 0.009 inches. Finally, the shell passageway


406


at axial locations F preferably has the largest axial width


432


, which is preferably larger than the axial width of the preformed tumblers


422


by a width D


4


of about 0.015 inches.




While the proximal wall


434


of the shell passageways


406


are generally aligned with the proximal wall


436


of the plug passageways


418


, the distal wall


438


of the shell passageways


406


are disposed further toward the plug tail


412


, or distally, than the distal walls


440


of the plug passageways


418


. Thus, a gap of axial widths D1-D4 remains ahead of the shearable tumbler portions


442


.




In the assembly of the lock


400


, the plug


408


is inserted into the interior cavity


404


of the shell


402


along a center axis


424


such that the shell passageways


406


and plug passageways


418


are aligned creating the gap


444


to produce a shear distance


446


between the shell


402


and the plug collar


410


of the plug


408


. The tumblers


422


are inserted in the aligned plug and passageways


406


and


418


as in the previous embodiment. The plug


408


is thereafter forced axially into the shell


402


over the shear distance


446


, shearing tumblers


422


and closing the gap


444


between the shell


402


and plug collar


410


. The shear distances required for shearing each of the tumblers


422


inserted in the shell and plug passageways


406


and


418


are different for the tumblers


422


located at different axial locations C-F. Thus, the plug must be moved by a distance greater than D1 to shear the tumblers


422


at locations C, by a distance greater than D2 to shear the tumblers at locations D, by a distance greater than D3 to shear the tumblers


422


at locations E, and by a distance greater than D4 to shear the tumbler


422


at location F. As a result, the two tumblers


422


at C are sheared first. Then the two tumblers


422


at locations D and then at locations E's are sheared, and finally the tumbler at location F is sheared. This configuration of the shell


402


thus reduces the force required for shearing of the tumblers


422


, as less than all of the tumblers


422


are being sheared at anyone time, or at least the tumblers at different locations are in different stages of shearing at any point in time. The shearing of the tumblers


422


is thus staggered. The maximum force required to shear the tumblers


422


is thus 2/7 of the maximum force that would be needed if all of the tumblers


422


were sheared simultaneously.




The same effect can be achieved by providing equally sized shell passageways, but spaced unequally from each other. The disposal of the distal walls


438


of the shell passageways


406


at different distances from the tumblers


422


will ensure that less than all of the material that constitutes the shearable portions


442


of the tumblers


422


is sheared at one time, reducing the shearing force required to form the plug portions


448


.




Another embodiment of the invention is shown in

FIGS. 23 and 24

. The retention sleeve has been removed for clarity. In

FIG. 23

, the lock


500


has a front portion


502


, a back portion


504


and a center axis


506


. Lock


500


further comprises a shell


510


and a plug


512


having shell and plug passageways


513


and


514


, respectively, axially positioned in a series. Shell passageways


513


extend through the shell


510


forming shell shearing walls


515


and plug passageways


514


extend through the plug


512


, forming shearing walls


516


at the interface therebetween. In addition, each shell passageway


513


has a shell front wall


516


located toward the front portion


502


of the lock


500


and a shell back wall


518


located toward the back portion


504


of the lock


500


. Similarly, each plug passageway


514


has a plug front wall


519


located toward the front portion


502


of the lock


500


and a plug back wall


521


located toward the back portion


504


of the lock


500


.




Tumblers


520


are inserted within the passageways


513


and


514


. Each tumbler


520


has a front lateral side or shearing surface


522


facing the front portion


502


of the lock


500


and a back lateral side or shearing surface


524


facing the back portion


504


. The front and back sides


522


and


524


define the shearing portion of the tumbler


520


. The walls of the plug and shell passageways of the previous embodiments were shown as parallel with respect to each other and substantially perpendicular to the longitudinal axis of the lock. In contrast, the back walls


518


of the shell passageways


513


form a shearing angle


526


with a line perpendicular to the longitudinal axis


506


of the lock


500


. Similarly, the back walls


521


of the plug passageways


514


form the same shearing angle


526


with a line perpendicular to the longitudinal axis


506


. The shear angle


526


is preferably less than 20° and more preferably less than about 15°. Most preferably, the shear angle


526


is about 5°.




Each tumbler


520


has a first lateral end


528


and a second lateral end


530


where the first lateral end


528


is located closer to the back walls


518


and


521


of the shell and plug passageways


513


and


514


than the second lateral end


530


.




The passageways


514


of the lock


500


are positioned such that when an axial shear force is applied to the plug


512


in a direction parallel to the center axis


506


from the back portion


504


to the front portion


502


of the lock


500


, the front walls


516


and


519


gradually begin contacting the first lateral side


522


of the tumblers


520


, and the tumblers


520


are pushed toward the back walls


518


and


521


as the tumblers


520


are sheared across the cross-section thereof from the first lateral end


528


to the second lateral end


530


. The angled back walls


518


and


521


substantially secure the first lateral ends


528


in place and allow gradual movement of the tumblers


520


such that only the second lateral ends


530


are allowed to pivot toward the back walls


518


and


521


. The shearing persists until the entire lateral surface of the tumbler


522


is sheared. Accordingly, shearing of the tumblers


522


occurs from the first lateral end


528


to the second lateral end


530


laterally across the tumblers


522


. As the contact of the front walls


516


and


519


with the tumbler


520


is not the entire lateral surface of the tumblers


520


at any point in time, less shearing force is required to shear the tumblers


522


than shearing tumblers in an embodiment having parallel front and back walls of shell and plug passageways.




Additionally, about half of the back walls


518


and


521


are angled in a first lateral direction, and about the other half of the back walls


518


and


521


are angled in the opposite lateral direction. The net effect of the angled passageways


513


and


514


is that the back walls


518


and


521


tend to twist the plug


512


in one direction, increasing the force of the tumblers


522


against the back walls


518


and


521


that are oriented in the opposite direction. Accordingly, the lateral orientations of the back walls


518


and


521


of the passageways


513


and


514


are preferably staggered axially to prevent the front portion


502


of the plug


512


from being twisted one way while the back portion


504


is twisted the opposite way, thereby stabilizing the lock


500


during the shearing process.





FIGS. 25 and 26

illustrate an apparatus that may be used for mounting the lock assembly in a loading position and for applying the shearing force required for shearing the tumblers. The shearing apparatus


600


includes a fixture


602


, which may be a wrench, with a lock holder


604


having a substantially semicircular holder recess


606


for receiving the lock


100


and a plunger


608


connected to the fixture for pivotal movement with respect to the holder


604


. Lock


100


, in its loading position with its shell


102


, plug


108


, key


116


and unsheared tumblers


122


placed within the shell


102


and plug


108


, is placeable in the holder recess


606


of the holder


604


. Lock


100


is placed within the holder


604


by inserting the holder


604


into and abutting the walls of a circumferential groove


610


on the shell


102


such that the walls of the groove


610


abuts the holder recess


606


with the plunger


608


abutting the external surface of the plug collar


110


.




To shear the tumblers


122


, lock


100


, including shell


102


, plug


108


, key


116


and tumblers


122


, in the loading position with the shearing gap


150


, is placed in the lock holder


604


with the shearing gap


150


between the circumferential groove


610


and the plug collar


110


. A force is applied to the lock


100


by pivoting the plunger


608


toward the holder recess


606


, and the plug collar


110


is forced axially toward the circumferential groove


610


, effectively closing the gap


150


and shearing the tumblers


122


. After the tumblers


122


are sheared, the plunger


608


is released and the lock


100


, now fitted for key


116


, is removed from the shearing apparatus


600


by sliding the holder


604


away from the groove


610


.




EXAMPLE




The above described aspects of the lock constructed according to the present invention will now be described with reference to the following non-limiting examples. These examples are merely illustrative of one of the preferred embodiments of the present invention and are not to be construed as limiting the invention, the scope of which is defined by the appended claims. These examples illustrate several of the above described manners in which the total shear force required to shear the tumblers is minimized while maximizing the total rotative torque strength of the tumblers to maintain the level of security desired for the lock.




Table 1 is a tabulation of the test results using a lock having tumbler with arcuate grooves, as shown in

FIGS. 5 and 6

, stamped across the lateral surface of the tumblers and a substantially cylindrical plug. Table 2 is a tabulation of the test results using a lock having tumbler with substantially straight grooves, as shown in

FIGS. 18 and 19

, stamped across the lateral surface of the tumblers and a plug having a correspondingly straight or flattened surface across the openings of the plug passageways, as shown in

FIGS. 20 and 21

. Other common parameters included the shell having an inside diameter of 0.686 inches at the inner cavity and a plug having an outside diameter of 0.680 inches, creating a shell and plug shearing zone of 0.006 inches. The tested tumblers were made from hardened brass having a groove thickness of 0.004 inches. The plug and shells were made from zinc plated metals. The varied parameters, in addition to the shape of the grooves stamped on the tumblers included the outside thickness of the tumblers


313


as shown in

FIG. 19

, shear contact angle


526


between the shearing surface of the back walls


518


and


521


and the back tumbler side


524


, as shown in FIG.


23


. Tumblers having outside thickness of 0.012 inches and 0.005 inches were tested. Shearing angle


526


of 0°, 4° or 8° as shown in FIG. were also tested.




The tests measured the required shearing force to shear the tumblers to a configuration in which the lock is operable with a particular key. These tests also measured the torque strength of the operable portions of the tumblers against the passageways, corresponding to the amount of torque the tumbler can resist when the plug is forced rotationally in the shell with the tumblers in the locked position. As stated earlier, it is desirable to maximize the rotative torque strength of the tumblers while minimizing the axial shearing force required for manufacturing a lock that is easily fitted with any insertable key.












TABLE 1











Arcuate/Curved Grooves
















Shear Angle (°)










angle of contact










between the










passageways and










the tumblers




Tumbler




Shear




Torque







(as shown in




Thickness




Force




(lb-in)






Example




FIG. 23)




(in)




(lbs)




Strength


















A1




0




0.005




200




31.75






A2




4




0.005




70.6




31.75






A3




4




0.012




100




51.75






A4




8




0.005




41




31.75






A5




8




0.012




71




51.75






















TABLE 2











Straight Grooves
















Shear Angle (°)










angle of contact










between the










passageways and










the tumblers




Tumbler




Shear




Torque







(as shown in




Thickness




Force




(lb-in)






Example




FIG. 23)




(in)




(lbs)




Strength


















S1




0




0.005




230




45.25






S2




4




0.005




67.8




45.25






S3




4




0.012




100




47.5 






S4




8




0.005




54.5




45.25






S5




8




0.012




91




47.5 














These tests demonstrated generally that a tumbler having a thickness of 0.012 in. requires greater total shear force than a tumbler having a thickness of 0.005 in. The maximum torque strength of tumblers, or the maximum rotative torque applied between the shell and plug that the tumblers were able to withstand before failing, varied more significantly between the two thicknesses for tumblers having arcuate grooves than for tumblers having straight grooves. A lock having arcuately grooved tumblers and angled contact surfaces between the passageways and the tumblers required less total shear force to shear the tumblers than a lock without angled contact surfaces between the passageways and the tumblers. By reducing the contact surface between the passageways and the tumblers at any point in time during shearing, the total shear force required for shearing is significantly reduced. Similarly, a lock having straight grooved tumblers and angled contact surfaces require 43% of the total shear force required to shear the tumblers than a lock without angled contact surfaces. Most notably, a lock having 0.005 in. thick tumblers and an 8° shear contact angle between the passageways and the tumblers required only 24% of the shear force than a lock having the same tumblers but without the angled shear contact surfaces, while maintaining the same tumbler torque strength.




It will be appreciated that those skilled in the art may devise numerous modifications and embodiments. It is intended that the following claims cover all such modifications and embodiments as fall within the true spirit and scope of the present invention.



Claims
  • 1. A lock, having a longitudinal axis and comprising:(a) a shell having an interior cavity; (b) a plug received in the interior cavity rotatable therein and defining a keyway configured to receive a preselected key; (c) at least one spring disposed within the plug; and (d) a plurality of tumblers, each having: (i) a plug portion disposed at one of a plurality of first axial locations along said axis and within the plug wherein the plug portion is resiliently biased by the at least one spring radially outwardly toward a locked radial position and associated with the keyway such that said preselected key inserted in the keyway locates the plug portion in an unlocked radial position; and (ii) a shell portion disposed at one of a plurality of second axial locations along said axis and within the shell wherein the second axial locations are axially spaced from the first axial locations.
  • 2. The lock of claim 1, wherein said shell and plug portions of each one of the tumblers are portions of a single tumbler sheared from each other at a location between the plug and the shell such that:(a) when the plug portion is in said locked radial position, the plug portion is disposed in an interface position with the shell to restrict relative rotation of the plug within the shell; and (b) when the plug portion is in the unlocked radial position, the plug portion is disposed in a non-interface position with the shell to permit the rotation of the plug within the shell.
  • 3. The lock of claim 2, wherein:(a) a plurality of said tumbler plug portions are disposed at axially spaced locations within said plug and biased outwardly from the plug; and (b) the shell further comprises an external surface and a plurality of passageways extending radially from said interior cavity toward the external surface for receiving a plurality of said tumbler shell portions.
  • 4. The lock of claim 3, wherein the shell further comprises at least one first locking channel extending from said interior cavity toward said external surface for engaging said plug portion of the tumbler in said locked position.
  • 5. The lock of claim 1, wherein said shell portion is out of alignment with said plug portion.
  • 6. A lock, comprising:(a) a plug defining a keyway for receiving a preselected key; (b) a plurality of tumblers receivable in the plug for radial movement therein; (c) a shell having an interior cavity and an exterior surface and defining a plurality of passageways radially connecting the interior cavity to the exterior surface for receiving the tumblers and further defining a locking space extending from said interior cavity toward said exterior surface to receive the tumblers in locking association therein for preventing rotation of the plug; and (d) at least one spring disposed within the plug for biasing the tumblers radially outwardly from the plug; wherein the plug is rotationally and axially receivable within the interior cavity about a rotational axis, and the tumblers are receivable through the passageways for insertion into the plug in a loading position and arc out of alignment with the locking space wherein said plug and interior cavity of said shell define a shearing zone such that when the plug and shell are biased axially with respect to each other with a preselected axial shearing force, the tumblers are sheared to an operative position having a plug portion and a shell portion, the plug portion of said tumblers in the operative position permitting rotation of the plug within the shell in an unlocked position and interfacing with the shell to restrict relative rotation of the plug in a locked position, wherein the at least one spring is disposed for biasing the tumblers toward the locked position.
  • 7. The lock of claim 6, wherein each tumbler has a plurality of weakened zones having a weaker strength relative to the rest of the tumbler with one of said weaker zones disposed at said shearing zone in said loading position when said preselected key is inserted in said keyway.
  • 8. The lock of claim 7, wherein:(a) the tumblers further comprise opposed sides connected by edges such that said weakened zone extends laterally across the sides in a predetermined shape; and (b) said plug has a shearing edge associated with said plug portion of said tumblers and defining an outer contour having generally said predetermined shape for supporting the plug portion upon the application of said axial shearing force.
  • 9. The lock of claim 8, wherein said predetermined shape is arcuate.
  • 10. The lock of claim 8, wherein said predetermined shape is substantially straight.
  • 11. The lock of claim 6, wherein the tumblers are movable within the plug in different radial directions with respect to the plug.
  • 12. The lock of claim 6, wherein said shell further defines a groove extending circumferentially about the exterior thereof for engaging a tool for applying said preselected force.
  • 13. The lock of claim 6, further comprising a retention sleeve mountable around the exterior of the shell in a position covering the passageways for retaining the tumblers therein.
  • 14. The lock of claim 13, wherein the retention sleeve defines sleeve slots alignable with the passageways for loading the tumblers into the plug therethrough.
  • 15. The lock of claim 14, wherein:(a) first and second of the shell passageways arc axially spaced along said rotational axis; and (b) first and second sleeve slots are angularly displaced about the rotational axis by an angle such that the sleeve is positionable on the shell in: (i) a first loading position in which the first sleeve slots are radially aligned with the first shell passageways with the second sleeve slots out of alignment with the second shell passageways, and (ii) a second loading position in which the second sleeve slots are radially aligned with the second shell passageways with the first sleeve slots out of alignment with the first shell passageways, each sleeve slot and corresponding shell passageway when aligned permitting the insertion therein of one of said tumblers.
  • 16. The lock of claim 6, wherein said locking space is angularly displaced about said rotational axis from said plurality of shell passageways.
  • 17. The lock of claim 16, wherein said locking space is angularly displaced about said rotational axis from said plurality of shell passageways by an angle of about 90°.
  • 18. The lock of claim 6, wherein said locking space comprises a locking channel extending substantially in parallel to said rotational axis.
  • 19. The lock of claim 6, wherein said locking space is out of alignment with said shell portions.
  • 20. A lock having a longitudinal axis, comprising:(a) a shell including an interior cavity and a plurality of shell passageways having opposed lateral shell walls extending laterally of said longitudinal axis; (b) a plug defining a keyway and being axially slidably receivable in the interior cavity and defining a plurality of plug passageways having opposed lateral plug walls radially aligned with said shell passageways; (c) a tumbler disposed in each of said aligned shell and plug passageways and associated with the keyway such that a preselected key inserted in the keyway locates the tumblers in an unlocked radial position, each tumbler having: (i) a plug portion with a first shearing surface facing one of the opposed lateral shell and plug walls, the first shearing surface of all of the plug portions collectively comprising collective first shearing surfaces, and (ii) a shell portion with a second shearing surface facing another opposed shell and plug walls, the second shearing surface of all of the shell portions collectively comprising collective second shearing surfaces; and (d) the shell portions of said tumblers being attached to the plug portions in a pre-formed configuration and shearable from the plug portions of the tumblers to a formed configuration upon axially biasing one wall of the plug toward the opposite wall of the shell with a predetermined axial shearing force; and (e) wherein the opposed walls of the shell and plug passageways are in association with the tumblers for progressively contacting the total collective first or second surfaces during the application of said preselected axial shearing force for shearing the tumblers.
  • 21. The lock of claim 20, wherein the wall of each plug and shell passageways facing in a direction opposite the direction of the axial shearing force applied to said first collective shearing surfaces is oriented at an acute shearing angle with respect to the opposite wall of each plug and shell passageway.
  • 22. The lock of claim 21, wherein the acute shearing angle is between about 2° and 15°.
  • 23. The lock of claim 20, wherein the wall of each plug and shell passageways facing in a direction opposite the direction of the axial shearing force applied to said first collective shearing surfaces is oriented at an acute shearing angle with respect to the tumblers.
  • 24. The lock combination of claim 20, wherein the opposed lateral shell walls of a first shell passageway are spaced axially from each other by a first distance and the opposed shell walls of a second shell passageway are spaced from each other by a second distance different than the first distance.
  • 25. The lock combination of claim 24, wherein the plug portions of said tumblers in said formed configuration are disposed in:(a) an unlocked position permitting rotation of the plug within the shell; and (b) a locked position interfacing with the shell to restrict relative rotation of the plug within the shell.
US Referenced Citations (31)
Number Name Date Kind
1295351 Morgan Feb 1919
1505865 Costa Aug 1924
1650568 Hurd Nov 1927
1789757 Jacobi Jan 1931
1828747 Perry Oct 1931
1953535 Hurd Apr 1934
1958603 Bacon May 1934
1979939 Jacobi Nov 1934
2151245 Swilens Mar 1939
2252966 Fogelson Aug 1941
2555316 Cerf, Jr. Jun 1951
2739473 Quillen Mar 1956
2820360 Soref et al. Jan 1958
3070987 Baker et al. Jan 1963
3073146 Patriquin Jan 1963
3078705 Morrison, Jr. Feb 1963
3125878 Gutman Mar 1964
3167943 Schreiber et al. Feb 1965
3175378 Russell Mar 1965
3234768 Russell et al. Feb 1966
3293893 Chesler Dec 1966
3563071 Barger Feb 1971
4103526 Surko, Jr. Aug 1978
4185480 Pechner Jan 1980
4412437 Smith Nov 1983
4440009 Smith Apr 1984
4741188 Smith May 1988
5211044 Kim May 1993
5265454 Crocco et al. Nov 1993
5697239 Hanneman et al. Dec 1997
5735153 Hanneman et al. Apr 1998
Foreign Referenced Citations (3)
Number Date Country
266379 Oct 1913 DE
2624320 Jan 1977 DE
1528882 Dec 1989 SU