Retaining Means For A Lock Cylinder Plug

Abstract

A method of retaining a rotary plug within the cylinder of a lock cylinder assembly where the lock cylinder has a cylindrical opening extending therethrough to receive a cylindrical plug having a stop only at the rear end thereof to align the holes or slots in the plug with the corresponding holes or slots in the cylinder. With the key removed, the tumblers biased across the shear line between the plug and cylinder retain the plug in the cylinder and, when the key is inserted into the plug to align the ends of the tumblers with the shear line and release the plug, a stop on the key extending beyond the plug's diameter to engage the cylinder face prevents rearward movement of the plug in the cylinder.

Description

The present invention relates to a novel plug construction for a lock cylinder assembly and a novel means of retaining the plug in operative position in the cylinder at all times.

In a conventional pin or plate tumbler lock, the cylinder or housing has a cylindrical passage therethrough counterbored at its face. A generally cylindrical rotary plug is conformably received in the cylinder and has a flange at the forward end received in the counterbore. To retain the plug in the cylinder, the plug is either provided with a groove adjacent the rear end to receive a retaining ring cooperating with the rear end of the cylinder, or is provided with a groove adjacent its rear end and located within the cylinder to receive the inner end of a retaining pin projecting thereinto from the cylinder. The present invention obviates the necessity of a plug groove and retaining means thereon by a simple alteration of the plug and key therefor.

Among the objects of the present invention is the provision of a novel retaining means for a rotary plug in the cylinder of a lock cylinder assembly. A lock cylinder is provided with a cylindrical passage therethrough and a cylindrical rotary plug having a rear stop shoulder is inserted into the cylindrical passage from the rear end of the cylinder. The tumblers biased outwardly by the tumbler springs across the shear line of the lock assembly prevent removal of the plug from the cylinder with the key removed. The key has an additional stop thereon extending beyond the diameter of the plug to engage the face of the cylinder and prevent rearward removal of the plug.

Another object of the present invention is the provision of a lock cylinder assembly having a simplified rotary plug. The use of the retaining means on the key plus the retaining function of the tumblers with the key removed allows the omission of the usual flange or enlarged heat at the forward end of the plug. Alsp the present retaining means eliminates the plug groove and the retaining ring or the retaining pin cooperating therewith.

A further object of the present invention is the provision of lock cylinder assembly and novel plug retaining means which provides for expanded keying potentionals. Elimination of the plug groove and the corresponding retaining ring or pin allows that area of the plug and cylinder to be used for an additional tumbler to expand the keying potentials of the lock.

Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

In the drawings:

FIG. 1 is a perspective view of one embodiment of the lock cylinder assembly and key of the present invention.

FIG. 2 is an exploded perspective view of the lock cylinder assembly of FIG. 1.

FIG. 3 is a side elevational view of the lock cylinder assembly and key of FIG. 1.

FIG. 4 is a vertical cross sectional view taken on the line 4--4 of FIG. 3 with the key omitted.

FIG. 5 is a rear elevational view of the lock cylinder assembly.

FIG. 6 is a side elevational view of the lock cylinder.

FIG. 7 is a perspective view of a second embodiment of lock cylinder assembly and key.

FIG. 8 is a vertical cross sectional view taken on the line 8--8 of FIG. 7 with the key omitted.

FIG. 9 is a side elevational view of the lock cylinder assembly.

FIG. 10 is a side elevational view of the lock plug.

FIG. 11 is a rear elevational view of the lock cylinder assembly.

FIG. 12 is a side elevational view of the key for the lock assembly of FIG. 7.

Referring more particularly to the disclosure in the drawings wherein are shown illustrative embodiments of the present invention, FIGS. 1-6 disclose a pin tumbler lock 10 adapted to be mounted in a door or other member to actuate a suitable lock bolt (not shown). The lock includes a cylinder 11 having an offset cylindrical passage 12 therethrough, and pin tumbler passages 13 extend from the outer periphery of the cylinder to intersect the passage 12 at the shear line 14 thereof. A recess 15 in the cylinder periphery extends over an arc of approximately 270.degree. and includes the outer ends 16 of the passages 13, and an arcuate spring clip 17 is adapted to be recieved in the recess 15 and close the outer ends 16 of the tumbler passages 13, the clip 17 resiliently gripping the cylinder 11 (FIG. 4).

A generally cylindrical rotary plug 18 has a rear stop shoulder 19 and a flat face 21 and is conformably received in the cylindrical passage 14; the shoulder 19 positioning the plug so the face is flush with the face 22 of the cylinder 11. The plug 18 includes an axially extending keyway 23 and a plurality of transverse tumbler passages 24 normally aligned with the passages 13 in the cylinder 11. The passages 24 receive a series of pin tumblers 25, while the passages 13 receive a plurality of drivers 26 and springs 27 with the springs abutting the interior surface of the clip 17 at the ends 16 of the passages 13.

To assemble the lock assembly 10, the rotary plug 18, which may have the pin tumblers 25 in position in the passages 24 is inserted in the rear end 28 of the cylinder 11 and moved forwardly until the stop shoulder 19 engages the end of the cylinder. Then the drivers 26 and springs 27 are inserted in the passages 13 and the clip 17 is positioned in the recess 15 and snapped onto the cylinder 11, thus compressing the tumbler springs 27. At this point, the drivers 26 extend across the shear line 14 between the cylinder 11 and the plug 18 to both prevent rotation of the plug and prevent rearward removal of the plug 18 from the cylinder.

When a standard key (not shown) having the proper bittings is inserted into the keyway 23, the bittings will actuate the pin tumblers 25 and the drivers 26 against the force of the springs 27 and, when the key is fully inserted, the lines between the pin tumblers and drivers will coincide with the shear line 14. Once the shear line is made, then the plug will rotate in the cylinder, but it will also move axially toward the rear of the cylinder because there is no enlarged head on the plug 18 bearing against the cylinder to prevent this axial movement. The consequence of such movement is that the pin tumblers 25 will fall out of the plug 18 as the pins become free from cylinder confinement. Also, the drivers 26 would drop out of the passages 13 when uncovered by the plug.

To prevent axial movement of the plug 18, a modified key 29 is provided with a shank 31 having bittings 32 and has an additional stop 33 which extends from the key beyond the plug diameter and protrudes into the area of the cylinder's face 22. Thus, when the key 29 is inserted into the keyway 23 and the bittings 32 actuate the pin tumblers 25 to release the plug 19, the stop 33 on the key overlaps the plug face 21 and the cylinder face 22 and abuts the cylinder face 22 to prevent rearward movement of the plug 18 and key 29 relative to the cylinder 11. The plug is provided with one or more projections 34 on the rear end adapted to actuate a lock bolt (not shown) in a manner well known in the art.

This simplified system of retaining the plug 18 within the cylinder 11, either with or without the key 29 inserted in the keyway 23, provides a measure of economy as modification of the key is the only expense, and savings lie in the elimination of the plug groove and retaining ring or retaining pin in the cylinder. Either the use of the retaining ring or the retaining pin involves the expense of the additional pieces as well as the assembling expense. Also, the elimination of the groove in the plug with its corresponding ring or pin in the cylinder allows that area of the plug and cylinder to be used for an additional tumbler, thus expanding the keying potential of the lock. Thus, the length of cylinder that would ordinarily accept four tumbler holes now allows for five tumbler holes.

This same manner of plug retention can be applied to a plate tumbler lock assembly 10.sup.a, as seen in FIGS. 7 to 12. The lock cylinder 35 is provided with the offset cylindrical passage 36 to receive a rotary plug 37 having a front face 38 and a rear radial stop shoulder 39 with a motion limiting radial tab 41 thereon. A plurality of transverse slots 42 having enlarged portions 43 are longitudinally aligned in the plug to receive the plate tumblers 44 and tumbler springs 45. Each tumbler spring 45 is received in an enlarged portion 43 and bears against a shoulder 46 in the plug and against a lateral arm 47 on the tumbler. Each plate tumbler 44 has a generally central slot 48 receiving the bitted shank 49 of a key 51 inserted into the keyway 52 extending generally axially through the plug 37. The plug also has one or more rearward projections 53 adapted to cooperate with a lock bolt (not shown).

The lock cylinder 35 is also provided with a pair of oppositely disposed channels or slots 54,54 on opposite sides of the passage 36 to receive the outer ends 55 of the plate tumblers 44 biased by springs 45 to prevent rotation of the plug 37 in the cylinder. The face 38 of the plug 37 is flush with the front face 56 of the cylinder, and the rear end 57 of the cylinder has an annular recess 58 to receive the stop shoulder 39. The recess 58 is provided with an arcuate enlargement 59 providing stop shoulders 61,61 cooperating with the stop tab 41 to limit rotary motion of the plug 37.

As in the previous embodiment, an ordinary key (not shown) inserted in the keyway 52 retracts the plate tumblers 44 so the ends 55 are withdrawn from the slot 54 to permit rotation of the plug. However, as there is no retaining ring or pin in the cylinder 35, the key and plug 37 are free to move rearwardly out of the cylinder. However, the modified key 51 (FIG. 12) has a bitted shank 49 and a radial stop 62 extending beyond the face 38 of the plug 37 and onto the face 56 of the cylinder 35, so when the key 51 is inserted into the keyway 52, the stop 62 abutting the cylinder face 56 will prevent rearward movement of the plug. The rear edge 63 of each slot 54 in the cylinder also cooperates with the outer end 55 of the rearmost plate tumbler 44, when the tumblers are in their locked positions (see FIG. 8), to prevent rearward movement of the plug 37 when the key 51 is withdrawn.

The same cost reductions mentioned for the pin tumbler lock assembly 10 of FIGS. 1-6 will also apply to the plate tumbler embodiment of FIGS. 7-12. Also, an arcuate spring clip 64, identical to the clip 17 of FIGS. 1-6 is received in a recess 65 and covers the open ends of the slots 54,54, as seen in FIG. 8.

Claims

I claim:

1. In a lock assembly comprising a lock cylinder having a passage extending longitudinally therethrough and a cylindrical rotary lock plug conformably received in the passage with the face of the plug flush with the face of the cylinder, means to retain the rotary plug within the lock cylinder including a radial stop shoulder on the rear end of the plug abutting the rear end of the cylinder, at least one pair of oppositely disposed slots in each cylinder, at least one plate tumbler in the plug, each tumbler normally biased to extend across the shear line between the plug and the cylinder into one of said pair of associated slots to prevent rearward movement of the plug relative to the cylinder, and a suitable key actuating the tumblers to allow rotation of the plug, said key having a stop abutting the cylinder to prevent rearward movement of the plug and key relative to the cylinder.

2. In a lock assembly as set forth in claim 1, in which the cylinder including an arcuate spring clip received on the cylinder to cover the outer ends of the slots.

3. In a lock assembly as set forth in claim 1, in which the stop on the key extends beyond the plug to overlap and abut the face of the cylinder when the key is fully inserted into a keyway in the plug.

4. In a lock assembly as set forth in claim 1, in which the rear edge of a slot cooperates with the projecting end of the rearmost plate tumbler to prevent rearward movement of the plug relative to the cylinder.

5. In a lock assembly as set forth in claim 1, in which said arcuate clip completely covers the slots.

6. In a lock assembly as set forth in claim 1, including cooperating means on the plug and cylinder to limit rotation of the plug relative to the cylinder.