Abstract:
An electrically controlled strike including a strike frame; a keeper carried by said strike frame for movement when released allowing door opening and adapted to receive and resist door opening prior to keeper movement; an electrically powered solenoid carried by said frame; means operatively connected between the solenoid and the keeper for causing the keeper to assume a fail-safe condition allowing keeper movement when said solenoid is unpowered or alternatively a fail-secure condition preventing keeper movement when said solenoid is unpowered; the two conditions being selected by repositioning an actuator.

Description:
[0001]    This patent application claims the benefit of Provisional Patent Application No. 60/232,223, filed Sep. 13, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates generally to the field of door security systems. More specifically, this invention relates to an improved electrically energizable, solenoid operated, door-strike mechanism that is easily switchable, to either of two different selected modes of operation. In one mode of operation the mechanism is in a fail-safe mode, wherein, if power to the solenoid fails, a keeper moves to allow a door to be safely opened. The other mode is called fail-secure, wherein, if power to the solenoid fails, the keeper secures the door against opening.  
         BACKGROUND OF THE INVENTION  
         [0003]    Electric strikes for securing hinged or swinging doors are well-known in the field of door security systems. The electric strikes are employed with doors having projectable deadbolts or latch bolts that engage the electric strike. The electric strike can be configured to secure the door alone, or in combination with other conventional security systems. The electric strike typically is mounted to the door frame and defines an opening in the jam face of the door frame for receiving the latch bolt and/or deadbolt from the lockset mounted to the door. The electric strike further defines an opening in the frame face contiguous with the opening in the jam face of the door frame. A pivotal keeper on the electric strike selectively closes the opening in the frame face. A bolt, projecting from the edge of the door, engages the electric strike through the opening in the jam face. Actuation of the electric strike locks or unlocks the keeper. The keeper is pivotable to uncover or open the frame face opening to allow the bolt to swing there through, and thereby allow opening of the door. The keeper is pivoted by the door being pushed, whereby the bolt engages the keeper of the strike.  
           [0004]    The lock assembly of a conventional electric strike is commonly operated by a solenoid. The solenoid is typically configured to be spring-biased so that energization of the solenoid overcomes the biasing force of the spring to either lock or unlock the electric strike. In a first configuration the power must be continuously supplied to the solenoid in order to maintain the electric strike in a locked condition. This configuration requires a relatively high and continuous input of energy and therefore, typically requires electrical wiring to the doorway from an electric line source.  
           [0005]    Similarly, electric strikes that are configured to unlock upon energization can also require a continuous supply of energy in order to maintain the lock in unlocked condition.  
           [0006]    There is a need for electrically-controlled strike mechanisms of simple, compact, construction for securing doors against opening (fail-secure mode), and also for allowing door opening (fail-safe mode), in the case of power failure. Most mechanisms permitting these two functions require two different strike devices, each device permitting only one of these functions. Current mechanisms which embody the two functions in a single mechanism require complicated disassembly and reassembly in order to accommodate both modes of operation. This invention permits alternating between fail-safe and fail-secure operation by simply turning a single part, an actuator, 180°.  
         SUMMARY OF THE INVENTION  
         [0007]    Briefly stated, the electric strike in the preferred form employs a solenoid to transform the electric strike between the locked and unlocked states. The solenoid allows for the use of an on-board power source, such as batteries, or an exterior power source to energize the electric strike. In the event that the power source is terminated, for example, because of power failure, it may be desired that the electric strike automatically engages in a fail-safe or alternatively a fail-secure mode. The electric strike includes a means operatively connected between the solenoid and the keeper for causing the keeper to assume a fail-safe condition allowing the keeper to pivot when the solenoid is in either position, or alternatively a fail-secure condition preventing the keeper from pivoting when the solenoid is in either position. In the present invention, the means connecting the solenoid to the keeper can be configured in either mode by simply opening the strike, removing a solenoid assembly and actuators, turning the actuator over and reinserting the removed parts. This permits easy selection of either mode by an unskilled human operator, in the field, in a short period of time, without complicated disassembly and reassembly of the strike mechanism.  
           [0008]    The actuator is a simple, unique, mechanical connection between a solenoid assembly and a lock link that permits or prevents the keeper from unlocking. The actuator is designed to operate in either of two positions. With one side up, the actuator is spring-biased to push the lock link into a fail-safe mode if the solenoid is unpowered. The actuator can be removed and reinserted with the other side or opposite side up. In this second position, the actuator is spring-biased to push the lock link into a fail-secure mode if the solenoid is unpowered.  
           [0009]    It is an object of the invention to provide an improved and relatively compact electric door strike for controlling access through a doorway with a mechanism that permits alternatively selecting a fail-safe condition or alternatively fail-secure condition with a simple easy mechanical reconfiguration that can be accomplished quickly in the field.  
           [0010]    It is another object of the invention to provide an electric strike mechanism that can be selectively configured in a fail-safe or fail-secure mode without a special operator, special tools or the addition of external devices.  
           [0011]    These and other objects of the invention will become apparent from a review of the specification and the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a partially exploded perspective view, of an electric strike in accordance with the invention;  
         [0013]    [0013]FIG. 2 is an exploded perspective view, of a backbox assembly of the electric strike of FIG. 1;  
         [0014]    [0014]FIG. 3 is a front perspective view, with a backplate, solenoid assembly, and actuator removed, of the backbox assembly of FIG. 1;  
         [0015]    [0015]FIG. 4 is a partial front view of certain components inside the backbox assembly of FIG. 1, shown in an unlocked position of the electric strike;  
         [0016]    [0016]FIG. 5 is a partial back view of certain components of the backbox assembly of FIG. 1, shown in an unlocked position of the electric strike;  
         [0017]    [0017]FIG. 6 is a front view of the actuator, solenoid attachment plunger and lock link of FIG. 4 assembled with the electric strike in fail-safe mode;  
         [0018]    [0018]FIG. 7 is a front view of the solenoid assembly, actuator, and lock link of FIG. 6 assembled in a fail-secure mode; and  
         [0019]    [0019]FIG. 8 is a perspective view of the actuator shown in FIG. 2. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]    With reference to the drawings wherein like numerals represent like parts, an electric strike is generally designated by numeral  10 . The electric strike  10  comprises one main assembly and two mounting parts. Referring to FIG. 1, the main assembly is called a backbox assembly  20 . The mounted parts comprise a face plate  14  and a lip attachment  16 . The face plate  14  is attached by flat-head screws  17  to the lip attachment  16 . The backbox assembly  20  is attached to the lip attachment  16  by button-head screws  18 , and the face plate is attached to a door frame (not shown) by additional flat-head screws  19 .  
         [0021]    The backbox assembly  20  includes a keeper  12  and wires  25  for connection to a power source to power the electric strike  10 .  
         [0022]    The electric strike  10  is mounted to a vertical edge of a door frame (not shown). The electric strike  10  can preferably, without modification, be readily mounted to a door frame with either left or right opening doors. The door (not shown) will have conventional lock hardware including a latch set with a latch bolt or deadbolt that extends from the door edge for engagement with the electric strike  10 . The electric strike  10  is positioned in a cut out through a door frame face and jam face of the doorframe.  
         [0023]    Referring now to FIG. 2, the backbox assembly  20  is shown in an exploded form. The backbox assembly  20  has a strike or backbox frame  21  that constitutes principal support structure of the strike. The backbox frame  21  defines a jam face opening  27  that, after assembly, is oriented within a door frame toward a door and generally coplanar with a jam face of the door frame. The jam face opening  27  forms a locking cavity whereby the bolt of a lock on the door can be captured to lock the door, or swing there through to allow opening of the door.  
         [0024]    Locking and Unlocking  
         [0025]    Referring again to FIG. 2 the backbox assembly  20  contains three main locking components. These components are a keeper  12 , lock arm  22  and lock link  24 . These components interact to provide the strike with locking and unlocking capabilities. The locking and unlocking of these three components is controlled by a fail-safe/fail-secure mechanism comprising an actuator  30 , and a solenoid assembly shown generally at  41 , solenoid attachment  44 , solenoid  40  with a plunger  42 .  
         [0026]    In operation of the components shown in FIG. 2, electrical power is supplied to or cut off from the strike  10  to lock or unlock the keeper  12  depending on the user&#39;s preferred mode of operation. This either retains a latch on the door lock in the locking cavity or allows the latch to rotate the keeper and open the door. The user specifies which mode the strike is to be in by setting the mechanism appropriately to take constant supply of power or no power at all to lock or unlock the door.  
         [0027]    Locking is accomplished by the respective orientation of the three main locking components contained in the backbox assembly  20 . Referring to FIGS. 2 and 3 these components are shown and, in FIG. 3, the components are shown in a locked position. The keeper  12  rotates or swivels about a keeper pin  15  oriented along the X axis (as shown in FIG. 2) of the assembly. The keeper pin  15  is not visible in FIG. 2 but is shown in FIGS. 3, 4 and  5 . Referring again to FIGS. 2 and 3 the lock arm  22  rotates about the lock pin  28  oriented along the Y axis (as shown in FIG. 2) of the assembly. The lock link  24  pivots about its own pin  29 , also oriented to swivel or rotate along the Y axis. The lock arm  22  blocks the keeper&#39;s rotation and a lock link  24  blocks the lock arm&#39;s rotation when the strike is in its locked position. The unlocked position occurs when the keeper  12  and the lock arm  22  are allowed to rotate about their respective axes.  
         [0028]    Referring now to FIGS. 4 and 5, a portion of the backbox assembly  20  is shown in an unlocked position. In FIG. 5, the lock arm  22  is shown rotated away from the keeper  12  which permits the keeper  12  to rotate about its keeper pin  15 . This unlocked position is accomplished by rotating the lock link  24  with the fail-safe/fail-secure mechanism thus unblocking the lock arm  22 .  
         [0029]    Fail-safe and Fail-secure Modes  
         [0030]    The fail-safe/fail-secure mechanism controls the locking and unlocking of the lock link  24  and thereby the locking and unlocking of the strike  10 . Actuation of the lock link is directly controlled through an actuator  30 . The actuator  30  also controls the fail-safe (FS) and fail-secure (FSE) interchangeability of the strike  10 . The actuator  30  is shaped as a pivoting arm and has two bosses  31  and  32  (best shown in FIG. 8). The two bosses are provided on opposite sides of the actuator  30 . The actuator  30  also has a slot  33  located at one end of the actuator  30  opposite the end upon which boss  31  is located. Referring now to FIGS. 4, 6,  7 , and  8  it can be seen how the slot  33  interacts with a lock link actuator pin  35  on the lock link  24 . When the actuator  30  is pivoted or rotated, the lock link is pivoted or rotated to block or unblock the lock arm  22  when voltage is supplied to the solenoid  40 . When the strike  10  is in the FSE or FS mode, one boss on the actuator pivots about a respective FSE hole  49  or FS hole  48  on the separator plate  26 , and the other boss on the actuator  30  interfaces with the solenoid attachment  44 . The solenoid plunger  42  is attached to a solenoid attachment  44  providing the necessary physical motion from the solenoid  40 . Therefore, when the solenoid plunger  42  is pushed in or out this operates the solenoid attachment  44  which ultimately causes rotation of the lock link  24 . Correspondingly rotation of the lock link  24  blocks or unblocks movement of the lock arm  22 .  
         [0031]    It is been stated previously that an object of this invention is to facilitate simple and easy changeover from fail-secure to fail-safe mode or vice versa. Referring now to FIG. 2 the strike  10  can be changed from fail-secure to fail-safe mode by removing backplate screws  47  from the back plate  50  on the backbox assembly  20 . The solenoid  40  along with the plunger  42 , plunger spring  43 , and solenoid attachment  44  is removed by lifting it along the Y axis. The actuator  30  is then rotated 180°, or turned over, and replaced so that the boss that was in a solenoid attachment hole  45  is now inserted into the fail-safe hole  48  in the separator plate  26 . The lock link pin  29  is again located in the actuator slot  33 . The solenoid assembly is replaced in the backbox assembly  20 , oriented as before except that the solenoid attachment hole  45  is now oriented over the available boss  32  on the newly available side of the actuator  30 . This boss  32  was previously located in the fail-secure bole  49  in the separator plate  26 . The back plate  50  and screws  47  are then replaced to complete the backbox assembly.  
         [0032]    Changing from fail-safe to fail-secure mode is done in the same manner. However, an actuator boss  31  is inserted in the fail-secure hole  49  on the separator plate  20 , and the solenoid attachment hole  45  is oriented over the remaining actuator boss  32 . The actuator  30  can be configured in different embodiments and still perform the functions described.  
         [0033]    This unique design of the actuator  30  and its ability to interact with the solenoid attachment  44 , separator plate  26  and lock link  24  ultimately provides a very simple and efficient mechanism that permits easy changeover between fail-secure and fail-safe mode while the strike is in the field. This changeover is done in a manner that is repeatable without destruction of the mechanism. The ability to change from fail-safe to fail-secure modes and vice versa quickly is a main feature of this invention. This change can be made quickly because of the accessibility to the fail-safe fail-secure mechanism. It requires minimal part removal, and the simplicity in which the mechanism can be interchanged involves only one part reorientation. The user can reduce installation time and complexity as a result. This strike  10  allows the user to inventory only one strike that handles fail-safe and fail-secure job requirements instead of two different strikes or mechanisms.  
         [0034]    Many existing products in this market require multiple parts to be removed for interchanging between fail-safe and fail-secure modes. Other products have only one mode of operation, and it must be specified when ordering the strike from the factory. The present invention provides a complete package of field-selectability to the end user without the common disadvantages.  
         [0035]    Preferred embodiments of the present invention have been illustrated and described. It is to be recognized that modifications will be well within the ability of those skilled in the art. Therefore, the appended claims are intended to cover any and all modifications which fall within the scope of the invention.