Cylinder lock assembly with a tailpiece rotationally coupled to the cylinder plug

The present application relates to lock assemblies that provide a secondary coupling point, utilizing an anti-rotation pin or extended tailpiece leg or other method, which rotationally couples the tailpiece to the cylinder plug, thereby preventing rotation of the tailpiece independently of the cylinder plug. Therefore, a tailpiece within a bolt cam or other actuator used to withdraw a bolt or unlock a lockset cannot be rotated after the tailpiece connector connecting the tailpiece to the cylinder plug has been forcibly removed, severed, or destroyed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to an improved cylinder lock assembly. In particular, the present invention discloses a cylinder lock assembly that maintains a rotational coupling between a cylinder plug and a tailpiece in the event that the connection between them is forcibly breached.

2. Description of the Related Art

Cylinder lock assemblies are known in the art. In general, a cylinder lock assembly may comprise a cylinder plug and a tailpiece. The tailpiece is normally operatively coupled to a deadbolt, latch or the like on one end and to the cylinder plug on the other end, thereby coupling the cylinder plug to the deadbolt or latch. When the cylinder plug is rotated—e.g., by inserting and turning an appropriate key—it causes the tailpiece to rotate, which then causes a reciprocal retraction or extension of the deadbolt or latch. Typically, the cylinder plug, and therefore the tailpiece, can only rotate when the proper key is inserted into the plug. A problem associated with this kind of lock, however, is that a tailpiece may be made to rotate independantly of a cylinder plug by forcibly disconnecting the without the insertion of the proper key.

As is conventional with cylinder locks of the type shown, cylinder plug10may include a plurality of radially arranged tumbler shafts16for receiving tumbler pins (not shown). A tailpiece20is connected to the rear end12of the cylinder plug by means of screws, bolts, or other suitable fasteners1extending through fastener holes22of a tailpiece retainer (retainer plate)18and into a fastener-receiving hole24formed in the cylinder plug10. The cylinder lock is operated by means of a key (not shown) inserted into a keyway opening at the front end14of the cylinder plug to thereby rotate the cylinder plug10about its longitudinal axis within the housing. Rotation of the cylinder plug10causes a corresponding rotation of the tailpiece20and tailpiece retainer plate18. The tailpiece20is coupled to a bolt or a door-latching mechanism (e.g., a lockset) in a known manner to cause reciprocal retraction and extension of the bolt or latch due to the rotation of the tailpiece20.

It has been suggested that the cylinder lock shown inFIG. 1can be breached by inserting a thin rigid object (e.g., a punch) into the keyway, such that the object extends through the rear end26of the keyway and against the retainer plate18or the end of the tailpiece20, and thereafter applying a sharp impact force to the rigid object, thereby shearing or otherwise disabling the fastener(s)1connecting the tailpiece retainer plate18to the cylinder plug10. With the tailpiece retainer plate18disconnected from the cylinder plug10, the tailpiece retainer plate18and the tailpiece20can be rotated independently of the cylinder plug10. Accordingly, if a narrow tool can be inserted into the keyway to grasp and rotate the tailpiece retainer plate18and tailpiece20, the bolt or door latching mechanism can be retracted without rotating the cylinder plug10, and thus the lock can be bypassed without a key.

Thus, there is a continued need for new and improved cylinder lock assemblies that prevent the deadbolt or latch from being operated even when the tailpiece has been forcibly disconnected from a cylinder plug.

SUMMARY OF THE INVENTION

A goal of the invention is to improve the security of cylinder locks by enabling such locks to resist attacks, such as by a punch hammered through the keyway of the lock. Accordingly, aspects of the invention are embodied in a cylinder lock assembly constructed and arranged to maintain a rotational coupling between the cylinder plug and the tailpiece in the event the conventional connection between the plug and the tailpiece (e.g. screws, clips, caps, etc.) is forcibly breached. More specifically, aspects of the invention are embodied in a cylinder lock assembly which includes a rotational coupling element for rotationally coupling the tailpiece to the cylinder plug so that the tailpiece cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug when the assembly is installed, for example, in a door, and regardless of whether the tailpiece is normally connected to the cylinder plug.

In the context of the this disclosure, a distinction is made between (a) a “connection” between the tailpiece and the cylinder plug, such as the conventional connection described above in which the tailpiece is fixedly attached to the cylinder plug, and (b) rotational “coupling” provided in accordance with aspects of the present invention whereby, although not fixedly attached to one another, the tail piece and cylinder plug are physically engaged so that the tail piece cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug.

According to one embodiment of the present invention, a cylinder lock assembly includes a cylinder plug that is rotatable about its longitudinal axis, a tailpiece adapted to operatively couple the cylinder plug to a deadbolt or a door latch actuator and configured so as to rotate with the cylinder plug when the tailpiece is connected to the cylinder plug, and a coupling element rotationally coupling the tailpiece to the cylinder plug so as to prevent the tailpiece from rotating about the longitudinal axis of the cylinder plug independently of the cylinder plug when the tailpiece is not conventionally connected to the cylinder plug.

The coupling element may, for example, include one or more anti-rotation legs integrally formed with and extending from the tailpiece into openings formed in the cylinder plug. Alternatively, the coupling element may comprise a structural interface, such as a pin or projection extending from the tailpiece retainer plate. The assembly may include a tailpiece retainer cap as opposed to a retainer plate, and a structural interface rotationally coupling the retainer cap to the cylinder plug may include an anti-rotation pin or other extension projecting from the cylinder plug into an opening formed in the retainer cap or a flattened surface formed on a side of the cylinder plug that engages a mating flattened surface formed in the interior of the retainer cap.

According to another embodiment of the invention, a method is provided for rotationally coupling the tailpiece to the cylinder plug of a cylinder lock assembly comprising the step of providing a coupling element that is fixed with respect to the tailpiece and extends axially into the cylinder plug at a location offset from the longitudinal axis of the cylinder plug.

According to another embodiment of the present invention, a method for modifying a cylinder lock assembly includes securing a pin to the tailpiece retainer plate such that the pin extends in a generally axial direction with respect to the cylinder plug and inserting the pin into an axial hole formed in the cylinder plug at a location offset from the longitudinal axis of the cylinder plug.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 2-10show various embodiments of a cylinder lock assembly constructed and arranged in accordance with the aspects of the present invention to prevent the tailpiece20from rotating about the longitudinal axis of the cylinder plug10independently of the cylinder plug10, while the tailpiece is still engaged with the dead bolt or door latch, should the tailpiece retainer plate18(or other means for connecting the tailpiece to the cylinder plug) be disconnected from the cylinder plug10, for example, as described in the Background above. More generally, the cylinder lock assembly includes a rotational coupling element for coupling the tailpiece to the cylinder plug.

In accordance with a first embodiment of the invention shown inFIGS. 2-4, the cylinder lock assembly includes a rotational coupling element in the form of an anti-rotation leg32extending from a shoulder34of the tailpiece30. The tailpiece shoulder34is configured to engage with the slot3in the rear end12of the cylinder plug, thereby configuring the tailpiece30to rotate with the cylinder plug10when the tailpiece is connected to the cylinder plug. The anti-rotation leg32extends into an off-center axial hole36formed in the cylinder plug10and extends axially toward the front end of the cylinder plug and beyond a tumbler shaft disposed closest to the rear end of the cylinder plug. The axial hole36is at a location that is offset from the longitudinal axis of the cylinder plug10. In the illustrated embodiment, axial hole36is a round, oblong hole formed in the plug10and extends axially toward the front end of the cylinder plug and beyond a tumbler shaft disposed closest to the rear end of the cylinder plug. Alternatively, hole36may be circular or rectangular or any other shape that will accommodate the leg32. Also in the illustrated embodiment, the tailpiece30, shoulder34, and anti-rotation leg32comprise a single, integrally-formed component. One of ordinary skill in the art, however, would appreciate that the tailpiece30, shoulder34, and anti-rotation leg32need not comprise a single component and each could, for example, comprise a separate component. Similarly, while the tailpiece30and the tailpiece retainer plate18are shown as separate components, they could be an integrally-formed, unitary piece.FIG. 3shows the assembly without the tailpiece retainer plate18to avoid obscuring the view of the tailpiece30.

Should the tailpiece retainer plate18be disconnected from the cylinder plug10as a result of shearing or otherwise disabling the fastener(s)1, the tailpiece retainer plate18, being confined within the structure of the door in which the lock is installed (not shown), cannot be moved in an axial direction sufficiently far away from the cylinder plug10to fully withdraw the anti-rotation leg32from the off-center hole36formed in the plug10. Accordingly, as shown inFIG. 4, with a portion of the anti-rotation leg32inserted into the off-center hole36of the cylinder plug10, and with a portion of the tailpiece30engaged with a deadbolt or door latch actuator (not shown), the tailpiece30is not able to rotate about the longitudinal axis of the cylinder plug10independently of the cylinder plug10. More specifically, because the axis of rotation A1of the tailpiece30and the cylinder plug10(i.e., the longitudinal axis of the cylinder plug10) is offset from the longitudinal axis A2of the anti-rotation leg32, the tailpiece30remains rotationally coupled to the cylinder plug10, even when the tailpiece30is disconnected from the end12of the cylinder plug10.

FIGS. 5 and 6show an alternative embodiment of the invention.FIG. 5is an exploded perspective view of a portion of a cylinder lock assembly including a cylinder plug10, a tailpiece35with two anti-rotation legs32a,32bthat are insertable into off-center holes36a,36bformed in the cylinder plug10. In the embodiment ofFIG. 5, holes36a,36bare circular, but they could be oblong (as inFIGS. 2 and 3) or rectangular or any other shape that will accommodate the legs32a,32b.FIG. 6is top plan view of the embodiment ofFIG. 5with the two anti-rotation legs32a,32bextending from the tailpiece35and partially inserted into the off-center holes36a,36bformed in the cylinder plug10. As shown inFIG. 6, with the anti-rotation legs32a,32binserted into the off-center holes36a,36bof the cylinder plug10, and with a portion of the tailpiece35engaged with a deadbolt or door latch actuator (not shown), the tailpiece35is not able to rotate about the longitudinal axis of the cylinder plug10independently of the cylinder plug10. More specifically, because the axis of rotation A1of the tailpiece35and the cylinder plug10(i.e., the longitudinal axis of the cylinder plug10) is offset from the longitudinal axes A2and A3of the anti-rotation legs32aand32b, respectively, the tailpiece35remains rotationally coupled to the cylinder plug10, even when the tailpiece35is disconnected from the end12of the cylinder plug10.

FIG. 7shows an alternative embodiment of the invention. The embodiment ofFIG. 7includes a tailpiece20and tailpiece retainer plate18, with a rotational coupling element in the form of an anti-rotation pin42extending through the tailpiece retainer plate18into an off-center axial hole46formed in the cylinder plug10. It would be understood by one of ordinary skill in the art that the tailpiece20and the tailpiece retainer plate18may comprise separate pieces, as shown here, or a single, integrally formed piece. Thus, the anti-rotation pin42provides a structural interface between the retainer plate18and the cylinder plug10to prevent the tailpiece20and the retainer plate18from rotating independently of the plug10when a portion of the tailpiece20is engaged with a deadbolt or door latch actuator (not shown). As with the embodiment described above, even with the tailpiece retainer plate18disconnected from the end12of the cylinder plug10, the anti-rotation pin42cannot be fully withdrawn from the off-center hole46, and thus the tailpiece retainer plate18and tailpiece20remain rotationally coupled to the cylinder plug10such that the tailpiece retainer plate18and tailpiece20cannot rotate independently of the cylinder plug10.

Thus, a conventional cylinder-tailpiece assembly, such as shown inFIG. 1, can be modified in accordance with an aspect of the present invention to rotationally couple the tailpiece20to the cylinder plug10by drilling a hole46in the plug10at a location that is offset from the longitudinal axis of the cylinder plug, drilling an aligned hole in the tailpiece retainer plate18, and inserting a pin42through the tailpiece retainer plate and into the off-center hole46.

In an alternative configuration to that shown inFIG. 7, pin42may be replaced or assisted by an axially extending projection formed integrally with the tailpiece retainer plate and which can be inserted into a hole or other opening formed in the cylinder plug10at a location that is offset from the longitudinal axis of the cylinder plug.

FIG. 8shows an alternative embodiment of the invention. This embodiment differs from others in that the circular or oblong hole36formed in the end12of the cylinder plug10is replaced with a rectangular hole56. Other shapes such as semicircular, oval, or polygonal—e.g., square, hexagon, octagon, triangle—may be used as well for the shape of the off-center hole56. Additionally, the hole56could be circular for a portion of its axial extent and rectangular or polygonal for a different portion of its extent. The anti-rotation leg32can be provided so as to have the same shape as hole56, in which case, for, e.g., a polygonal or semicircular hole, the leg32cannot rotate inside the hole56about axis A2. Similarly, an oblong hole that partially matches the shape of the leg, which will also result in the leg not being able to rotate within the hole.

As is shown inFIG. 9, in a further alternative embodiment, a blind, off-center anti-rotation hole formed into the end of the cylinder plug10is replaced by an axially-extending groove66formed in the outer surface of the cylinder plug10. When the anti-rotation leg32—or an anti-rotation pin42or an axial projection extending from the tailpiece retainer plate18—is positioned inside the groove66, the tailpiece20or30cannot rotate about the longitudinal axis of the cylinder plug independently of the cylinder plug. With a rectangular anti-rotation leg, as with anti-rotation leg32, having the same shape as the groove66, the anti-rotation leg32is unable to rotate within the groove66, thereby achieving an additional anti-rotation effect. As an alternative to the embodiment shown inFIG. 9, the cylinder plug may have two or more axially-extending grooves formed in the outer surface of the plug, and the tailpiece may have two or more anti-rotation legs, or pins, configured and arranged to extend into the grooves.

FIG. 10is perspective view of a portion of an alternative embodiment of a cylinder lock assembly with three anti-rotation legs32a,32b,32cextending from the tailpiece37and insertable into off-center holes36a,36b,36cformed in the cylinder plug10. Hole36cis an extension of the keyway (reference number26inFIG. 1). So that the third anti-rotation leg32cdoes not interfere with a key inserted into the keyway, it may be necessary to elongate the plug10(and thus elongate the keyway), for example, by forming the plug from a longer piece of cylindrical stock or by adding an extension piece13to a conventional-length plug. Extension piece13may, for example, be secured to the plug10by screw or other suitable fastener elements.

FIG. 11is perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug10, a tailpiece70, a tailpiece retainer cap76, and an anti-rotation pin82that extends from the cylinder plug10into an opening80formed in the tailpiece retainer cap76. A rectangular tailpiece opening78is formed in the retainer cap76. Tailpiece70extends through the opening78from inside the cap76, and shoulders74formed on the tailpiece70prevent the tailpiece from passing completely through the opening78. Retainer cap76fits over the end of the cylinder plug10and is secured to the plug10by mechanical fasteners (e.g., screws) or by press fit or other suitable means. So that the retainer cap76does not interfere with any of the tumbler holes, it may be necessary to elongate the plug10, for example by forming the plug from a longer piece of cylindrical stock or by adding an extension piece15to a conventional-length plug. Extension piece15may, for example, be secured to the plug10by screw or other suitable fastener elements. The assembly includes a structural interface rotationally coupling the retainer cap76to the plug10to prevent the tailpiece70and the retainer cap76from rotating independently of the plug10. In the embodiment ofFIG. 11, the structural interface is provided by the anti-rotation pin82inserted into a radially-oriented hole84formed near the end of the plug10. When the cap76is installed onto the end of the plug10, pin82extends into the opening80formed in the cap76. In the illustrated embodiment, opening80is a slot formed in the side wall of the cap76that extends to the end of the cap, but opening80may alternatively be a hole formed through the sidewall of the cap76. When the retainer cap76is unconnected to the plug10, the anti-rotation pin82extending through the opening80will prevent the cap76and the tailpiece70from rotating independently of the plug10.

As an alternative to the anti-rotation pin82shown inFIG. 11, the structural interface between the retainer cap76and the cylinder plug10may be provided by a radial fin or other projection extending from the cylinder into the opening80formed in the cap76. Furthermore, the assembly may include more than one pin, fin, or other projection extending from the plug and engageable with a corresponding opening formed in the cap.

FIG. 12is an exploded perspective view of a portion of an alternative embodiment of a cylinder lock assembly including a cylinder plug10, a tailpiece70, and a tailpiece retainer cap86. In the embodiment ofFIG. 12, the structural interface rotationally coupling the retainer cap86to the plug10is a flattened surface88formed in an extended portion19of the plug10which engages a mating flattened surface (not shown) formed in the interior of the cap86. Engagement of the surface88with a mating surface within the cap86will prevent the cap from rotating independently of the cylinder plug10. The assembly may include one or more additional flattened surfaces formed on the cylinder plug10which engage one or more corresponding mating surfaces formed in the interior of the cap.

Alternative structural interfaces for rotationally coupling the retainer cap to the plug may include mating grooves and ridges formed on the retainer cap and the cylinder plug or any other structural feature that will prevent the retainer cap from rotating independently of the cylinder plug.

Thus, a number of preferred embodiments have been fully described above with reference to the drawing figures. Other details of the embodiments of the invention should be readily apparent to one skilled in the art from the drawings. Although the invention has been described based upon these preferred embodiments, it would be apparent to those skilled in the art that certain modifications, variations, and alternative constructions would be apparent, while remaining within the spirit and scope of the invention.