LOCK CYLINDER HAVING TWO SETS OF TUMBLERS AND KEY THEREFOR

Abstract: The usual pin tumbler lock core 16 is provided with an additional set of security disc tumblers 50 adapted to engage contours 77 on the bottom rail of a key and in so doing the security tumblers are rotated as the key is inserted in the lock. When the proper key is fully inserted, gates 52a on the security tumblers all align to permit the inward movement of a side bar 62. The key, which is otherwise conventional, has a bevelled tip 82 and a security contour 77 on a lateral surface for activation of the security tum­ blers.

Description: This invention relates to a cylinder lock having the conventional pin tumblers which work on the profile of the upper edge of the key, and additional security or disc tumblers which work on a security contour cut on a lateral surface of the key. The invention also relates to a key for such a lock. The prior art teaches a number of cylinder locks having two sets of tumblers, as in U.S. Patent 4,434,636 issued to Prunbauer. This patent discloses a cylinder having the conventional set of pin tumblers working along the profile of the edge of the key, and a' second set of angled pin tumblers located entirely within the cylinder and aimed down at an enlarged rib along the bottom opposite edge of the key, the rib being contoured and the pins designed with recesses adapted to receive a side bar with the result that when the recesses of the auxiliary pin tumblers are aligned, the side bars are permitted to yield inwardly to allow the key to rotate the cylinder core. Danish Patent 73,832 discloses a cylinder having a core with a special pin which laterally engages an indentation in the center of the key to manipulate a special auxiliary pin tumbler in addition to the conventional pin tumblers working against the top of the key. The present invention is embodied in a lock and a key. The key is formed with a bevelled tip, and along its bottom rib in the preferred embodiment, with a security contour having surfaces parallel to the plane of the key. The key also has the conventional top bitting. The cylinder core of the lock is formed with a slot for the key, and also has disc-type security tumblers adapted to be partially rotated by engagement with the aforesaid security contour of the key. Gates are formed on the disc tumblers which when aligned allow the inward passage of the fence of a side bar to permit the cylinder core to be turned by the key. The lock of the invention is especially well adapted for use in a master key system wherein a lower level of security key may be used to open a cylinder lock without the security tumblers, but only the master key with the security contour opens the locks in accordance with the invention. At the same time the master key can operate the lower level locks. In the drawings: Figure 1 is a sectional view taken on the line 1-1 of Figure 2 of a cylinder lock embodying the invention; Figure 1a is an enlarged sectional view taken on the line 1a of Figure 1; Figure 2 is a vertical sectional view through the center of the cylinder shell but showing the cylinder core itself in profile; Figure 3 is an enlarged sectional view taken on the line 3-3 of Figure 2; Figure 3a is an enlarged perspective view of the side bar element; Figure 4 is an enlarged side elevational view of the key embodying the invention; Figure 5 is a bottom plan view; Figure 6 is a fragmentary sectional view taken on the line 6-6 of Figure 4; Figure 7 is an enlarged sectional view taken on the line 7-7 of Figure 4; Figure 8 is an enlarged sectional view taken on the line 8-8 of Figure 4; Figure 9 is an enlarged fragmentary sectional view similar to Figure 1 but showing the core with the proper key inserted and the disc tumblers aligned; and Figure 10 is a view similar to Figure 9 but showing the side bar moved inward after the cylinder core has been rotated. A cylinder lock 10 shown in Figure 1 comprises a cylinder shell 12 having a central opening and a perpendicular tailpiece 14. The shell 12 may take various other well-known shapes such as a mortise lock shell, a rim lock shell, etc. In the cylinder shell is rotatably disposed a cylinder core or plug 16 which is formed on its front end with a circumferential flange 18 (Figure 2) which rests rotatably inside a hardened steel ring shield 20 disposed in a recess in the front end of the shell 12. Bolted to the rear end of the core is the usual operator cam 24, the periphery of which butts against the rear end of the shell 12 and holds the core in the shell. Formed in the plug is the conventional key slot or keyway 26. Also formed in the plug and intersecting the upper end of the slot are a plurality of aligned vertical tumbler bores 28 which receive pin tumblers 30, the upper ends of which engage drivers 32. The drivers are disposed in tailpiece compartments 34 and are urged downwardly by springs 36. The upper ends of the springs are held down by the plate 38. The upper edge profile of the key works against the pin tumblers to determine the level of the respective meeting lines. Obviously, when the meeting line between each pin tumbler 30 and associated driver 32 coincide with the circumference of the cylinder plug 16, the plug, if otherwise free, may be turned. The plug is bored and filled with conventional hardened steel pins as at 39 (Figure 2). These, together with the ring shield 20, help to thwart the drilling out of the lock cylinder core. As shown, the front end of the cylinder shell may be covered by a sheath 40 of decorative metal. As shown in Figures 2 and 3 the side of the plug 16 is formed with a longitudinal recess 46. Preferably in between the pin tumblers 30, radial slots 48 are formed in the plug. In these slots are respectively disposed a plurality of security disc tumblers 50 which are shaped with an arcuate profile conforming to the curvature of the inside of the shell. The security tumblers are supported by the curved surface of the cylinder opening and the walls of the respective slots 48. As seen in Figure 1, the security tumblers extend into the bottom of the key slot 26. The curved outer profile of the security tumblers is interrupted by recesses 52. The recesses 52 each include a deeper central gate 52a flanked by shallower sections (preferably at certain levels in the respec­ tive security tumblers 50 for reasons which will appear). An enlarged bore 54 is shaped in each of the slots 48 to receive a security tumbler biasing spring 56 (Figure 1) which is bottomed upwardly in the inner end of its bore 54, and urges downwardly at its lower end against an associated security tumbler 50. The lower or keyway end 50a (Figure 1) of each security tumbler is chamfered and its inner end presents a contact point which is engaged by the bevel 82 of the key as will be described below. As shown in Figures 1, 9, and 10 the central opening of the cylinder shell is formed with a longitu­ dinal groove 58 to normally receive the rounded nose of the fence 60 of the steel side bar 62. The opposite side of the side bar is formed with spaced blocks 64 sized to be disposed in between the security tumblers 50 and serving to guide the side bar in recess 46. Springs 66 are disposed in wells 68 in the side bar and are bottomed at their inner ends against the inner face of the longitudinal recess 46. Referring now to Figures 4 through 8, the key for the lock cylinder of the invention is of generally conventional shape with vitally important exceptions. The key comprises a head 71 and a blade 72 formed with conventional longitudinal grooves or splines 74 and a bottom rail 76. Formed in the rail is the security tumbler-engaging contour 77. The contour 77 is ground off parallel to the plane of the key in order that it may be engaged at virtual right angles by the lower tips of the security tumblers 50. The upper edge 78 of the key has the usual top bittings to cooperate with the pin tumblers 30 in establishing the meeting lines between the pin tumblers and the drivers 32, all at the circumference of the plug. Further, the angled lower portion of the nose or tip 80 of the key is sharply bevelled off at 82 at approximately a 45° angle (Figure 6). As a result there is no need for the security tumblers 50 to be bevelled or cut in a special way to provide for easy counterclockwise movement from their fully rotated position (Figure 1) as the key enters the keyway. As the insertion progresses, the security contour 77 cut into the rail 76 permits the security tumblers driven by the springs 56 to move back in a clockwise direction into the depressions in the contour 77 with the result that the proper key rotates the security tumblers to a position with their gates 52a at a level even with the side bar 62. The full insertion of the key with the proper top bitting, of course, also causes the meeting line between the tumbler pins 30 and the drivers 32 to be at the level of the core circumfer­ ence. Subsequently, as the key and plug are urged to rotate, the fence 60 is cammed inwardly out of the groove 58 by the shape of the nose of the fence 60 and the shape of the groove as well. It will be understood that when the cylinder is returned by the key to its original position, the fence 60 will slide outwardly back into the groove 58 to create a detent "feel" to the lock, telling the operator that the key is in the withdrawal position. The subsequent removal of the key will permit the security tumblers 50 to move clockwise again to the position shown in Figure 1. Additionally, the tumbler pins 30, no longer raised by the top bitting 78 of the key, will drop down as the key is removed and the drivers 32 will block the rotation of the core. It should be noted that as the mechanism of the high security lock of the invention is all within the cylinder core, if there is a malfunction the removal and replacement of the core is a simple operation. A further advantage of having the mechanism within the cylinder core is that it does not require additional projections from the cylinder shell which could interfere with the installation of the shell in stan­ dard lock cutouts. Since the inward movement of the side bar 62 requires not only the proper conventional top bitting 78 but also the proper security contour 77 to rotatably align the security tumbler gates, the lock is extremely difficult to pick. Not only would the perpetrator have to raise each of the top tumbler pins 30 to the proper level, he would also have to push aside the security tumblers 50 to the proper position and in addition, insert a torque tool to turn the core. This is well beyond the capabilities of the most experienced perpe­ trator. Another advantage of the present lock is that the key is, aside from the security contour 77, entirely conventional and can be used with the properly set similar lock without the security tumblers 50 so that in a master key system, the master key of Figures 4 and 5 can open both the similar sub-master locks and the lock of the invention, while the sub-master keys without the contour 77 can only open the sub-master locks.

Claims: 1. A lock cylinder, comprising: a housing (12) having a cylindrical opening, a lock core (16) in the cylindrical opening and formed with a keyway (26) including a portion for a side rail (76) along the bottom edge of the blade of a key, the core and the housing being provided with conventional pin tumblers (30) and pin tumbler openings (34) above the keyway and adapted to engage conventional top edge bittings (78) on a key, the core also being formed with transverse slots (48) intersecting the keyway, partial disc tumblers (50) disposed in the respective slots and having ends disposed in the keyway portion, first spring means (56) urging the disc tumblers into the keyway portion, the disc tumblers being formed with gates (52a) on their outer periphery at selected points, a side bar (62) normally disposed partly in a recess (46) in the core and also partly in a longitudi­ nal groove (58) in the housing at one side of the cylindrical opening, the groove having sloping walls, second spring means (66) in the core urging the side bar outward, the side bar being cammed inward of the housing when the core is turned provided the proper key is in the keyway and a special contour (77) on the side rail of the key engages the ends of the disc tumblers to position the disc tumblers with their gates in alignment with the side bar and thereby permit the side bar to move inward totally into the recess in the core. 2. A lock cylinder as claimed in Claim 1 wherein the slots are spaced intermediate the pin tumblers. 3. A lock cylinder as claimed in Claim 1 wherein the side bar is formed with a plurality of spaced blocks (64) on its side inward from the housing and the blocks engage the sidewalls of the recess to guide the side bar as it moves inward. 4. A lock cylinder as claimed in Claim 3 wherein a pair of spaced blocks are formed with wells (68) facing inward of the core and the second spring means are disposed in the wells and bottom in the inward wall of the recess. 5. A lock cylinder as claimed in Claim 1 wherein the first spring means are housed in bores (54) in the core which define enlargements of the slots. 6. A lock cylinder as claimed in Claim 1 wherein the partial disc tumblers are supported by the walls of the cylindrical opening in the housing and the transverse slots in the core, and are capable of rotation about the axis of the cylindrical opening in the housing. 7. For use with a lock cylinder as claimed in Claim 1, a key having front and back surfaces and comprising a head and a blade, the blade having on its front surface along one longitudinal edge conventional edge bittings (78) and along the opposite edge a side rail (76), the side rail having a contoured edge code (77), the edge code extending a substantial part of the length of the blade and including a series of bittings defined by lines transverse of' the blade and substantially parallel to the plane of the key, the blade having at its end farthest from the head a nose portion including an incline plane (82) on the side rail tapering down from the front of the blade to meet the back of the blade in a fine edge. 8. In combination, a high security lock cylinder comprising a lock housing (12) and a rotatable core (16) with a keyway (26) disposed in the housing, the housing having a side bar groove (58) therein, a side bar (62) adapted to normally reside in the side bar groove, first spring means (66) in the core urging the side bar outward, the core having a plurality of partial disc security tumblers (50) having gate means (52a) at various levels respectively adapted to pass the side bar inward and having ends at the periphery of the core which in their normal position extend into the keyway, second spring means (56) urging the partial disc tumblers toward their normal position, and a key having conventional shape but having lateral contours (77) along an edge opposite the usual top edge bitting (78) and which, when the key is fully inserted in the keyway, hold the disc tumblers with their gates aligned at the level of the side bar, the cylinder and core also having the usual pin tumblers (30) engaging the edge bitting. 9. A lock cylinder and key combination as claimed in Claim 8 wherein the disc tumblers are disposed alternately with the pin tumblers along the length of the cylinder. 10. A lock cylinder and key combination as claimed in Claim 9 wherein the second spring means are disposed in bores (54) which are lateral enlargements of slots (48) which hold the disc tumblers in place.

Inventors: SURKO, WALTER E., JR.
Applicants: YALE SECURITY INC
Application year: 1986
Main classification: E05B15
IPC codes: E05B31