Locks – Special application – For closures
Reexamination Certificate
2002-12-10
2004-05-25
Walsh, John B. (Department: 3676)
Locks
Special application
For closures
C070S106000, C292S140000
Reexamination Certificate
active
06739162
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a simple deadbolt assembly for a hinged door. The deadbolt assembly includes a deadbolt, cam and opposing slide plates. The deadbolt is slideably mounted between the slide plates for movement between an extended position and a retracted position. The cam is rotatably mounted between the slide plates in engagement with the deadbolt, such that upon rotation of the cam, the deadbolt is actuated between the extended and retracted position. Leaf springs are utilized to support the deadbolt on the cam. The flexibility of the leaf springs eliminates bind between the deadbolt and the cam and results in a more fluid movement of the deadbolt.
RELATED ART
Deadbolt lock assemblies are typically utilized to prevent unauthorized opening of a door. With storm doors, the deadbolt assembly is mounted on the interior side of a door; with mortise locks, the deadbolt assembly is mounted within the edge of a door (the “mortise”), connected to a key cylinder body located on the exterior side of a door and/or a thumb turn button located on the interior side of the door by a spindle. Once a deadbolt is actuated to a locked position, it is desirable that the deadbolt not be inadvertently retracted, such as by application of an inward force on the deadbolt because this may create a condition known as “lock-out.”
The distance a deadbolt extends outwardly from the door faceplate and extends into a bore formed in the doorjamb (known as “throw”) varies. If the doorjamb is not properly prepared and provides too shallow a bore for receiving the deadbolt, the deadbolt may not fully extend. If the deadbolt is actuated by a key cam, the operator may not be able to lock the door, or the operator may not be able to retrieve the key because the deadbolt is not fully extended. Under these circumstances, the operator may attempt to force rotation of the key cam to obtain full extension of the deadbolt, causing the key cam to rotate out of engagement with the deadbolt. If the deadbolt partially retracts, the key cam may no longer be aligned for engagement with the deadbolt, so that the deadbolt cannot be fully retracted or extended. When this occurs, the door cannot be unlocked, constituting a “lock-out” situation. The only way to open a door under these circumstances is to remove the entire door, sometimes requiring the destruction of the door and/or lock.
A conventional design of a mortise deadbolt assembly consists of a deadbolt, side plates, a cam, a spring loaded position stop, detail in a side plate defining a guide path, and cam stops. The deadbolt is slideably mounted on the side plate for movement between an extended (locked) position and a retracted (unlocked) position. The cam is rotatably mounted to and between the side plates in engagement with the deadbolt for actuation of the deadbolt between its extended position and retracted position upon rotation of the cam.
The deadbolt is normally constrained in its extended position or retracted position by a spring loaded position stop mounted on the deadbolt for movement generally transverse to the line of motion of the deadbolt. The position stop is aligned with and extends through an opening formed in a side plate, defining a guide path for the stop. The guide path typically has an upside down “U” shape. The “legs” of the upside down U-shaped guide path reflect the retracted and extended positions of the deadbolt. When the stop is positioned in one of the two legs of the guide path, the deadbolt is fixed in its retracted position; when the stop is positioned in the other of the two legs of the guide path, the deadbolt is fixed in the extended position. Movement of the stop along the guide path between the legs permits the deadbolt to be moved between the extended and retracted positions by the cam.
The position stop is secured to a spring mounted to the deadbolt. Upon rotation of the cam, the cam engages the stop and the deadbolt. The force of the cam acting on the position stop causes the position stop to move up along one leg of the guide path as the deadbolt is transversely moved between the retracted and extended positions. As the deadbolt is moved to its new position, the position stop continues to travel through the guide path and down the second leg of the guide path, securing the deadbolt in its new position.
Cam stops are designed to limit the occurrence of lock-out situations by being strategically placed to limit rotation of the cam. Limiting rotation of the cam prevent the cam from completely disengaging the deadbolt. While cam stops provide more flexibility in the manufacturing process, if the dimensions, placement and tolerances of the position stop and guide path are not confined to strict requirements, it can still lead to lock-out, and even if strict requirements are maintained, the stops and guide path are subject to wear.
Under lock-out situations, the cam disengages the deadbolt and position stop while the position stop has not yet become constrained in one of the legs of the guide path. Minor inward forces on the deadbolt allow the deadbolt to slide inward so that the deadbolt is only partially extended, and the cam cannot re-engage the deadbolt and position stop to either extend or retract the deadbolt.
Thus, there is a need to develop a deadbolt lock assembly where lock-out is prevented. There is also a need to develop a deadbolt that cannot be inadvertently retracted from its locked or extended position.
BRIEF SUMMARY OF THE INVENTION
The present invention comprises a simple deadbolt that may be utilized as a surface lock typically provided with storm doors, or as part of a mortise door lock system. The simple deadbolt assembly is small allowing it to be used in most existing door applications. The simple deadbolt includes a lock body comprised of opposing side plates. A deadbolt is slideably mounted between the side plates for movement between a retracted position and an extended position. A key cam is rotatably mounted between the side plates and slideably supports the deadbolt and actuates movement of the deadbolt between the retracted position and extended positions upon rotation of the cam.
The key cam includes a cylindrical axle or shank with an actuating arm extending radially there from. The actuating arm supports a cylindrical guide at its outer end. The deadbolt includes a elongated opening for slideably receiving the cylindrical axle of the cam, and a guide channel contiguous and substantially perpendicular to the elongated opening for receiving the key cam guide. The key cam cylindrical axle is mounted within the opening of the deadbolt and is supported by opposing leaf springs mounted on the deadbolt along the longitudinal edges of the elongated opening.
The guide channel and deadbolt opening create a guide path for the cam guide. The guide extends into the guide channel and opening. Upon rotation of the key cam by a thumb turn button or key cylinder operatively connected thereto, the guide is rotated through the guide channel, applying a force to the side walls of the deadbolt that define the guide channel. the force of the cam arm being rotated into engagement with the deadbolt causes the deadbolt to slide between its extended and retracted positions. The leaf springs permit fluid movement of the deadbolt with respect to the cam and reduce wear.
These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.
REFERENCES:
patent: 551264 (1895-12-01), Walker
patent: 828780 (1906-08-01), Shepard
patent: 1060413 (1913-04-01), Augenbraun
patent: 1114368 (1914-10-01), Kramarczyk
patent: 1219318 (1917-03-01), Hyde
patent: 1613398 (1927-01-01), Ledin
patent:
Hardware Specialties, Inc.
Moss & Barnett
Schumann Glen E.
Walsh John B.
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