Patent Application
20080224481
1. Field of the Invention
This invention relates to strikes for doors, and in particular to electric strikes that can be changed to operate in fail-safe and fail-secure modes.
2. Description of the Related Art
Door locking mechanisms and security doors to prevent theft or vandalism have evolved over the years from simple doors with heavy duty locks to more sophisticated egress and access control devices. Hardware and systems for limiting and controlling egress and access through doors are generally utilized for theft-prevention or to establish a secured area into which (or from which) entry is limited. For example, retail stores use such secured doors in certain departments (such as, for example, the automotive department) which may not always be manned to prevent thieves from escaping through the door with valuable merchandise. In addition, industrial companies also use such secured exit doors to prevent pilferage of valuable equipment and merchandise.
Electric strikes, also known as electric door openers, are a class of door mechanisms that have been developed to control access to buildings or areas. An actuation means (e.g. an electrically driven motor or solenoid) is used to either block or release a rotatable keeper to either prevent or allow release of a door's latch bolt, to lock the door or allow it to be opened. Typically, electric strikes have two modes, namely a “fail-secure” mode (where the door is locked with the power removed, i.e. the actuation means must be triggered to allow the door to be opened), and a “fail-safe” mode (where the door is unlocked with the power removed, i.e. the actuation means must be triggered to prevent the door from being opened). Some strikes on the market have only one-mode capability, while others are dual mode allowing the installer to select which mode is desired at the time of installation.
Different dual-mode electric strikes have been developed such as the commercially available GEM model GK-300 and ROFO 2400 series models. Each has a solenoid mounted on a holder, which is movable within the strike housing. A blocking element is directly attached to the plunger of the solenoid, to block movement of the keeper when the strike is in its locked position. A first screw, reachable from outside the housing, cooperates with a slot in the housing, to define the path along which the holder is movable. When the first screw is tightened, it fastens the holder to the housing, i.e. the holder cannot move. First and second holes are arranged on the housing, to alternately align with a second screw, also reachable from outside the housing, so that at each end position along the holder path of movement, one of a threaded third or fourth hole, both arranged on the holder, is aligned with either the first hole or the second hole, and the second screw can be inserted into the appropriate first or second hole and screwed into the visible third or fourth hole. The installer can configure the GEM strike in either the fail-safe or fail-secure mode by selecting which holes are used. However, doing so is a tedious and tricky process, requiring proper alignment of holes, careful removal and replacement of one screw, and careful loosening of another screw.
U.S. Pat. No. 6,874,830 to Bashford describes an electric strike having a housing, a keeper pivotally arranged in the housing, and a holder slidably arranged in the housing. The electric strike also includes a blocking element slidably arranged in the holder. The blocking element is configured to selectively prevent a rotation of the keeper and allow the rotation of the keeper. The electric strike also includes a two-position mode selector operable from outside the housing, and the selector is configured to selectively move the holder from a first position to a second position and vice versa. The electric strike also includes an actuator configured to selectively move the blocking element. Specifically, when the holder is in the first position, the blocking member allows the rotation of the keeper when the actuator is energized and prevents the rotation of the keeper when the actuator is not energized, and when the holder is in the second position, the blocking member prevents the rotation of the keeper when the actuator is energized and allows the rotation of the keeper when the actuator is not energized.
One embodiment of an electric strike according to the present invention comprising a housing with a keeper pivotally mounted to the housing. An actuating device controlled by an electrical signal is arranged internal to the housing and movable between two positions. A mode control screw is mounted to the electrical strike and also capable of moving between two positions by loosening the screw, the movement of the screw causing movement of the actuating device between two positions. A blocking element connected to the actuating device. In one of the two mode control screw positions the blocking element blocks pivot of the keeper when the electrical signal is lost. In the other of the mode control screw positions the blocking element allows pivot of the keeper when the electrical signal is lost.
Another embodiment of an electric strike according to the present invention comprises a housing and a keeper pivotally mounted to the housing. A two position mode control slot is included in the housing. A mode control screw is included in the mode control slot and is capable of being movable between and tightened in each of the two positions in the slot without removal of the screw. The screw is changeable between the two of the positions by loosening the screw. The electric strike operates in fail-safe mode when the screw is in one of the two positions and fail-secure mode when the screw is in the other of the two positions.
Still another embodiment of an electric strike according to the present invention comprises a housing and a keeper pivotally mounted to the housing. A solenoid is arranged internal to the housing and movable between fail-safe and fail-secure positions. A two position mode control slot is included in the housing. A mode control screw in the mode control slot is capable of being tightened in each of the two positions in the slot. The screw is changeable between the two of the positions without removal of the screw. The solenoid is in the fail-safe position when the screw is in one of the two positions and in the fail-secure position when the screw is in the other of the two positions.
These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings which illustrate by way of example the features of the invention.
The present invention provides a simplified dual mode electric strike that allows for the user to change modes between fail-safe and fail-secure by the position of a single mode control screw. The mode control screw is accessible from outside of the housing and passes through a two position mode control slot in the housing. The screw turns into the threaded hole in a moveable slide that is internal to the electric strike housing. The slide contains blocking and actuating elements for operation of the strike in the dual modes. Movement of the slide between the two positions controls whether the electric strike operates in fail-safe or fail-secure mode. The position of slide is changed by loosening (and not removing) the mode control screw and moving it to one of the two positions in the mode control slot. As the screw is moved, the slide is also moved within the housing. When the screw is in the desired position it is then tightened. The slide is held in place by the holding force of the mode control screw and the surfaces of the housing.
It is understood that when an element or component is referred to as being “on”, “connected to” or “coupled to” another element, it can be directly on, connected to or coupled to the other element or intervening elements may also be present. Furthermore, relative terms such as “front”, “back”, “inner”, “outer”, “upper”, “above”, “lower”, “beneath”, and “below”, and similar terms, may be used herein to describe a relationship of one component of element to another. It is understood, however, that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.
Although the terms first, second, etc. may be used herein to describe various elements or components these elements and components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the present invention.
Embodiments of the invention are described herein with reference to certain illustrations that are schematic illustrations of idealized embodiments of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are expected. Embodiments of the invention should not be construed as limited to the particular shapes of the elements or components illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of an element or component and are not intended to limit the scope of the invention.
Referring now to
The housing 12 further comprises a face plate 18 that allows for mounting of the electric strike 10 into conventional door frame, and in particular a door jam. The electric strike 10 should be positioned within the door frame to cooperate with a conventional deadbolt or latch bolt of a door. The positioning and mounting of the electric strike 10 is known in the art and will not be discussed in detail herein. The housing 12 also comprises housing openings 20 for electrical conductors 22 to pass from the inside of the housing as best shown in
Referring now to
The housing rear portion 34 holds the keeper 14 and the strike's internal moving components. For the door to be locked, i.e. for the keeper 14 to be prevented from pivoting, the keeper has at least one abutting surface 38 that is blocked when the door is locked or when power is lost in a fail-secure mode. When the door is unlocked or power is lost in the fail-safe mode, the abutting surface 38 is not blocked and the keeper 14 is allowed to pivot.
The electric strike 10 further comprises actuating device 40 that can be controlled to block the abutting surface 38 when the door is locked and power is lost in the fail-secure mode. Different actuating devices 40 can be used, with a preferred device 40 being a solenoid. Solenoids are known in the art and only briefly described herein. As best shown in
The solenoid 40 can be mounted in the housing 12 in many different ways, with one mounting embodiment according to the invention shown in
The electric strike further comprises a movable slide 56, with the bracket 48 mounted to the slide 56. Many different mounting methods can be used such as mounting by screws or welding, with the mounting method as shown being by rivets 58.
A blocking element 60 is mounted to the solenoid 40 at the end of the extended plunger 44 and blocking element 60 moves as the plunger is extended from or drawn into the solenoid body 42. The blocking element is positioned in the housing 12 such that is can be moved to block the keeper's abutting surface 38 when the door is to be locked or power is lost in fail-safe mode. The blocking element 60 can have many different shapes and sizes, with a suitable blocking element being substantially square as shown. The slide 56 with its solenoid mounting bracket 48 is mounted within the housing's rear portion 34 by a mode control screw (shown and described below). The slide 56 can be moved within the rear portion 34 between two positions as described in more detail below. In the preferred embodiment, the two positions correspond to fail-safe and fail-secure operation of the electric strike 10.
The electric strike 10 can also be provided with different switches arranged in different locations to sense and report the status/position of certain components within the electric strike 10. The status/position of the components can then be monitored by a lock monitoring system.
A lock/unlock position switch 66 can be mounted to the slide 56 adjacent to the blocking element 60. When the plunger 44 extends from the solenoid body 42 the blocking element 60 actuates the position switch 66. The condition of the position switch 66 is reported by an electrical signal on the position switch conductors (wires) 68.
A keeper position switch 70 can be mounted to the housing rear portion 34 adjacent to the keeper 14, with the switch being activated by the pivot of the keeper 14. The condition of the keeper position switch 70 is reported on keeper position switch conductors 72.
A latch position switch 74 is also mounted to the rear portion 34 and cooperates with a latch lever 76 to sense and report to presence of a latch bolt within the electric strike 10. The lever 76 is rotatably mounted to the rear portion 34 with the engaging element 80 within the latch bolt opening 36 (best shown in
Referring now to
Referring to
Referring now to
Although the present invention has been described in detail with reference to certain preferred configurations thereof, other versions are possible. Therefore, the spirit and scope of the invention should not be limited to the versions described above.
