Locks – Special application – For closures
Reexamination Certificate
1999-08-13
2001-11-13
Gall, Lloyd A. (Department: 3627)
Locks
Special application
For closures
C070S162000, C070S492000, C070SDIG003, C070SDIG004
Reexamination Certificate
active
06314772
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to lock mechanisms. Particularly, the invention relates to lock mechanisms for emergency pull stations, such as pull stations for triggering fire alarms.
BACKGROUND OF THE INVENTION
In known fire alarm pull stations, a lever is provided which can be manually pivoted or depressed to set off a local or centralized fire alarm. Such fire alarms are typically present in buildings such as schools, hospitals, and the like The alarm pull stations mount on a wall and are typically color coded to be easily recognizable in an emergency.
Such pull stations are manufactured for example by Pittway Corpration, NOTIFIER division, such as model NBG-10 series Non-Coded Manual Fire Alarm Station, BGX-101L Addressable Manual Pull Station, BNG and BRG series Manual Fire Alarm Stations or LNG Double-Action Manual Fire Alarm Station.
To prevent vandalism or nuisance alarms involving such pull stations, the pull stations are configured to lock in place once the activation lever is depressed or otherwise placed in an alarm state. To reset a pull station, a key is required to release the lever to its initial, non-alarm state. Typically the pull station key is entrusted to a person of authority for a building, for example, or with fire department personnel.
Given long periods of time between alarm actuations, keys can become lost. Also, the person holding the key may be unavailable to reset the pull station.
There continues to be a need for lock mechanisms which, while secure, can be unlocked by a large group of people. Preferably such expanded capability could be provided at substantially the same cost as present locks and without requiring added space in the respective unit being secured.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, a lock mechanism includes a lock cylinder assembly which can be actuated by a preselected shaped key inserted into a correspondingly shaped key-receiving actuation socket, but which otherwise conceals the key-receiving actuation socket from view to prevent the unauthorized actuation of the lock mechanism. The invention is particularly useful when the key is a common tool, such as an Allen wrench. The lock mechanism is particularly useful in preserving any condition, or state of a device by preventing the unauthorized change or resetting of such condition or state, where such condition or state is intended to be changed or reset by an authorized person having possession of a key to the lock mechanism. The lock mechanism is particularly useful in preserving the locked security of housings for electrical devices, such as a housing for a pull station for an alarm system.
According to the invention, the lock mechanism includes an improved lock cylinder assembly. The lock cylinder assembly includes a lock actuation cylinder having a circular keyhole at one end thereof in registry with a hexagonal key actuation socket recessed deeper into the lock actuation cylinder. The actuation socket is shaped to receive a standard Allen wrench of a predetermined size as the “key”.
A single, interposed, spring-loaded tumbler plate penetrates the lock actuation cylinder so as to be interposed between the keyhole and the key actuation socket. The tumbler plate has an intermediate bore which is biased by a spring to be out of registry with the keyhole. During key actuated locking or unlocking, the tumbler is forcibly moved transversely to register the intermediate bore with the keyhole by insertion of the Allen wrench key. The key, if properly selected, will fit into the key actuation socket.
The lock actuation cylinder can be connected to a lock cam. Turning of the lock actuation cylinder causes the lock cam to engage external structure.
The lock cylinder assembly also includes a lock body which surrounds the actuation cylinder. A retaining ring secures the lock body to surrounding structure such as to a cover, wall or door to be locked.
The lock body includes at least one groove adjacent to the tumbler plate. The tumbler plate is biased to have a head portion thereof extending into the groove of the lock body in the absence of a key. This coaction prevents relative rotation of the lock actuation cylinder and the lock body. When a key is substantially completely inserted into the lock actuation cylinder, the tumbler plate is transversely moved such that the head portion thereof is retracted from the groove of the lock body to allow relative rotation between the lock actuation cylinder and the lock body.
The tumbler plate acts as a barrier to cover the observable shape of the key actuation socket to prevent the unauthorized opening by a person having access to Allen wrenches, given unrestricted visual observation of the size and shape of the key actuation socket by looking through the keyhole. With no key in the keyhole, the intermediate bore of the tumbler plate is sufficiently out of registry, either partially or totally, to prevent ascertainment of the correct shape needed to fit the key actuation socket. A variety of keys such as hexagonal or spline wrenches could be used.
According to another aspect of the invention, a pull station is secured by the aforementioned lock mechanism. The pull station includes a back plate or base plate which carries an alarm switch and a terminal block wired thereto.
A cover is hingedly connected to the back plate. The cover carries a pull handle slidably coupled thereto and accessible through an opening in a front wall of the cover.
The lock mechanism of the invention is installed in an opening in the front wall of the cover. When locked, the lock mechanism prevents the resetting of the pull station. Locking the cover to the back wall forms a closed configuration and prevents access behind the cover to reset the pull station.
The back plate includes a stepped surface extending forwardly thereof and in registration with a latch. As the handle is being slid, with respect to the cover and back plate, to activate the station, the latch slides on the stepped surface. In response to force from a spring, the latch extends behind a perpendicular surface of the stepped surface. The perpendicular surface prohibits the latch from moving in a reverse direction. This in turn prohibits the handle from being slid in a reverse direction.
In order to reset the handle to its initial, inactive position, the cover must be unlocked and opened. The latch can be released and the handle retracted. The cover can then be closed to the base plate and re-locked.
Thus, the lock mechanism of the present invention provides security against unauthorized opening and/or resetting of the pull station while at the same time allowing for a common tool to open and/or reset the pull station. The need to retain specially cut keys, and to find such keys when needed, is obviated.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which details of the invention are fully and completely disclosed as part of this specification.
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patent: 5172097 (1992-12-01), Arnold
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patent: 5927111 (1999-07-01), Nachbauer
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Notifier brochure, “NBG-10 Series Non-Coded Manual Fire Alarm Station,” 1995 (2 pages).
Notifier brochure, BGX-101L “Addressable Manual Pull Station,” 1995 (2 pages).
Three photographs (front, inside, rear) of Notifier Model BGX-101L Non-Coded Fire Alarm Box.
Notifier brochure, “BNG & BRG Series Manual Fire alarm Stations,” 1995 (2 pages).
Noti
Gall Lloyd A.
Pittway Corporation
Rockey Milnamow & Katz Ltd.
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