Abstract:
This electric strike mechanism has a housing, a keeper pivotally mounted in the housing, at least one locking element pivotally mounted within the housing, for pivoting between a first position where the keeper is prevented from pivoting, and a second position where the keeper is permitted to pivot so that the door can be opened, a solenoid connected to each locking element via an actuation mechanism to move each locking element when the solenoid is energized, and a spring biasing the solenoid towards a non-actuated position. The actuation mechanism may be installed in one of two orientations, namely a first (fail-secure) orientation wherein the locking element is in its first position when the solenoid is not energized and wherein energizing the solenoid moves the locking element to the second position, and a second (fail-safe) orientation wherein the locking element is in the second position when the solenoid is not energized and wherein energizing the solenoid moves said locking element to the first position.

Description:
REFERENCE TO RELATED APPLICATION 
   This is a formal application based on and claiming the benefit of U.S. provisional patent application No. 60/402,748, filed Aug. 12, 2002. 

   BACKGROUND OF THE INVENTION 
   This invention relates to an electric strike that is small enough to be used in multiple applications and can be configured in the field for fail-safe or fail-secure operation. 
   The field of electrically operated strikes is filled with a multitude of devices, which essentially do the same thing: they release a latch that extends into the body of the strike so as to open the door that contains the latch. They commonly use a solenoid which, through some mechanical linkage, will release the keeper holding the latch and then return to its locked condition after the latch is released. There are very few electric strikes whose keeper extends into a latch contained within the door and, upon energizing, not only rotates out of the latch, but also remains in its rotated condition until the door closes and the latch returns the keeper to its locked condition. For reference there are two such devices: an electric strike disclosed in U.S. Pat. No. 5,076,625 issued to Oxley on Dec. 31, 1991; and an electric strike called the Panicloc (trademark), formerly manufactured by SDC, Inc., of Westlake Village, Calif., USA. 
   The present invention is designed to control the most widely used concealed vertical rod exit devices that come as standard equipment on aluminum storefront type doors such as those made by the Dor-O-Matic Company, of Harwood Heights, Ill., USA. This exit device has been the largest selling exit device in the world, and yet, it has been the most difficult to adapt to electronic access control systems because it features a unique latching system. A U-shaped latch is mounted in the top of the door and does not extend beyond the outer edge of the door. A pin, which is mounted on the header, engages the latch. When the exit device is operated from the inside, the latch releases by the movement of the push bar, and the motion of the opening door forces the latch to pivot via the pin on the header. The pin then passes through a slot in the inside skin of the door as it opens. When the door closes, the header pin contacts the latch and rotates it back to its vertical (locked) position. As computerized access control becomes more necessary, more of these OEM devices will need to be controlled. The present invention provides a cost-effective solution to the drawbacks of the prior art devices. Additionally, since the adoption in the United States of the Americans with Disabilities Act, and similar legislation in other countries, a great many more of these existing doors need to be retrofitted with automatic door openers that require an electric strike to release the door. 
   The existing device referenced is the electric strike identified by U.S. Pat. No. 5,076,625. It features a keeper shaped with a lobe that extends into the U-shaped latch and swings out of the way when the strike is energized and the door is opened. That strike, in its preferred embodiment, is built on an existing electric strike body available from an established manufacturer to take advantage of a proven “platform” upon which to build. This was done to speed the product to market and avoid the costly task of making the strike from scratch. The “platform” strike is asymmetrically designed relative to where the keeper is placed in the body of the strike. This characteristic limits the useful application of the strike to include only a few possible applications. Additionally, the strike malfunctions after a particular combination of events occurs. When an authorized individual gains access, the strike is energized by the access control system. The motion of the door opening rotates the keeper out of the latch. Normally, the door closes, rotating the keeper back and re-locking it after the person has entered. If, however, the panic bar is pushed before the door closes, (for example if another person exits just after the entry is achieved), the latch rotates toward the inside of the door and hits the keeper as it tries to rotate back to its closed position. This causes an interference that keeps the door from closing and locking. There are also difficulties one encounters while installing the strike. The design of the platform strike situates the body of the strike behind the outside edge of the doorstop. Proper installation requires the installer to measure over the door stop “rib” in the header and lay out lines for the cutout needed to mount the strike. This proves to be difficult for installers and many are intimidated enough to not use the product. 
   Finally, the platform strike was never intended by its manufacturer to be a “finished” piece: it is always attached to a finished plate of a different shape. It takes a great deal of work to get the platform strike to look finished, and even then, the strike can only be made in two architectural finishes. 
   The other device, i.e. the Panicloc device, is an adaptation of a fail-safe solenoid powered bolt lock which mounts in a door header. It has a bolt that extends into a pocket installed in the top of a door by the application of electric current through a solenoid via a 90-degree lever. The Panicloc device utilizes the solenoid and lever system with a metal bolt that has a bevel on one side which extends into the latch. This device is not currently being made because it doesn&#39;t work well in this application. 
   There is one other device that is used to electronically control these doors, and that is the magnetic lock. However, since an electromagnetic lock requires that the mechanical exit device be removed from the door, this is not a preferred solution. Normal egress is disrupted. Normal access by key is lost. Additionally, in the event of a power failure, the door with a magnetic lock will be totally unlocked and unsecured. Many Fire Chiefs and Building Inspectors do not allow magnetic locks to be used on exit doors. 
   There is thus a need for an electric strike which can accommodate more mounting applications and is easier to install. It is desirable for the strike to be configured easily by the user to operate in either the “fail-safe” or the “fail-secure” mode. 
   SUMMARY OF THE INVENTION 
   In view of the preceding, the invention provides an electric strike mechanism having a housing, a keeper pivotally mounted in the housing, at least one locking element pivotally mounted within the housing, for pivoting between a first position where the keeper is prevented from pivoting, and a second position where the keeper is permitted to pivot so that the door can be opened, a solenoid connected to each locking element via an actuation means to move each locking element when the solenoid is energized, and a spring biasing the solenoid towards a non-actuated position. The actuation means may be installed in one of two orientations, namely a first orientation wherein the locking element is in its first position when the solenoid is not energized and wherein energizing the solenoid moves the locking element to the second position, and a second orientation wherein the locking element is in the second position when the solenoid is not energized and wherein energizing the solenoid moves said locking element to the first position. 
   In the preferred embodiment, the actuation means includes two locking bolts, and energizing the solenoid either moves the locking bolts behind the keeper to lock the door (fail-safe mode of installation), or away from the keeper to unlock the door (fail-secure mode of installation). 
   Further details of the invention will be described or will become apparent during the course of the following detailed description. 
   Advantages of the invention include: its size; its ability to be field configured for fail-safe and fail-secure operation; its ease of installation in any application; and its keeper. The keeper attends to the rotation of the aforementioned Dor-O-Matic (trademark) latch back to its locked position as it is itself rotated back to its own locking position. This eliminates the jamming problem that plagues prior devices. The new strike is smaller and mounts in required applications without modification. The strike is designed to simplify installation: all necessary cutting is done forward of the door stop rib. This satisfies a major complaint of prior device installers who have difficulty measuring and cutting over and through the doorstop. The strike, when installed, is to be adorned by a finished trim plate. These trim plates can be easily and cheaply stamped out of sheet metal in any architectural finish requested. This solves the problem of having to sand or paint the prior device&#39;s strike body in its entirety. 
   The strike also features the ability to change its mode of operation, even at the time of installation, without the need of extra parts or expenditure. It is not possible to reconfigure the prior strike in the field. All the configuring has to be done at the time that the order is placed for manufacture and consequently, limits the usefulness of each strike to a single type of application. This causes a lot of returns, delays, and unhappy customers. It also requires distributors to stock an extensive variety of strikes to fill customer orders. There is no way to take a prior strike and change it to suit a rush order for a differently configured strike. This causes problems with distributors who don&#39;t want to stock every possible variation. This results in many disruptions in manufacturing&#39;s production cycle in order to produce a “special” order in a rush situation. 
   The invention addresses these problems for the manufacturer, distributor, and installer. It permits one strike body to be used in any application just by selecting the correctly finished trim plate to match the order. Because the trim plates are inexpensive, the distributor and installer can stock a variety of them at a comparatively minimal cost. This allows the installer to carry fewer strikes to the job-site, and have fewer return trips per job. This also allows the distributor to sell a greater volume of strikes with less per piece special attention required filling orders. This also allows the manufacturer to benefit from fewer “rush order” interruptions to their normal production cycle. All of these features are a distinct improvement over prior devices. All of these features result in a more volume and profits for the manufacturer, distributor, and the installer. 
   Since the mechanism developed for this strike is relatively compact, it can be used in other embodiments, such as a rim panic strike, a 161 prep strike, and an ANSI standard size strike, among others. Installation of a typical rim panic strike requires cutting out a portion of the hollow metal door jamb to accommodate the mechanism or body of the strike, and often the door jambs are concrete filled. The concept of a flush mounted rim strike for an exit device is relatively new, but not novel. Prior patented rim strikes are generally larger, thicker, and longer than the strikes they are replacing. The invention makes possible a rim panic strike that can be very flat and small enough to replace the standard typical roller strike that comes as standard equipment for most exit devices. This results in a strike that will mount, using the same mounting screw holes as the non-electric roller strike, and that can be installed in matter of seconds, without any cutting, by anyone who can use a screwdriver. 
   The invention can be made small enough to fit the old standard jamb cutout (161 prep) that is 2¾″×1⅛″. This configuration, also referred to as the “T” strike cutout, is used widely in residential applications and almost exclusively in the modular office wall partition systems used today. Since the solenoid is housed within the small strike body, the normal extra depth cutout is not required. This saves labor time and expense during installation, and also preserves the structural integrity of the door jamb. This is especially important in residential applications that feature wooden doorjambs. In most electric strike installations, it is necessary to cut away the doorjamb to permit the latch a means of passage when opening the door. This is labor intensive, and can be unsightly in residential and commercial applications where there are fancy wooden or steel door casings that have to be cut out. When this new strike is installed with the accompanying special faceplate, any cutout for a raceway is not necessary. The small strike and ANSI embodiments will use a specially designed face plate that features a ramp for the latch to travel up and over the lip of the face plate without necessitating any further cutting. This ramp has a special shape that accommodates the auxiliary latch, which normally serves to block the latch from being “ramped” back into the door. This special faceplate will benefit the user in at least three ways. It will save time and expense of labor normally needed for installation of the strike. It will improve the appearance of the strike in the doorjamb and preserve the esthetic integrity of the existing door casing. Finally, it will improve the security of the door latch and lock by eliminating the need for a large “raceway” for the latch. Raceways usually serve to provide an opportunity for tool attack by anyone seeking to pry back the latch to bypass the door locking system. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in detail, with reference to the accompanying drawings of the preferred embodiment by way of example only, in which: 
       FIG. 1  is a side view, at rest in its locked position, of one embodiment of the invention; 
       FIG. 2  is a side view, at rest in its unlocked position, of the aforementioned embodiment of the invention; 
       FIG. 3  is a bottom view, at rest in its locked position, with the finished cover plate and screws; 
       FIG. 4  is a bottom view of the electric strike of  FIG. 3  with the keeper rotated to its unlocked or released position; 
       FIG. 5  is a bottom view of the electric strike of  FIG. 3  with the keeper and cover plate removed to show the underlying mechanism at rest in the locked position of the fail-secure configuration; 
       FIG. 6  is a bottom view of the electric strike of  FIG. 5  in the energized, unlocked position of the fail-secure configuration; 
       FIG. 7  is a bottom view of the electric strike of  FIG. 5  at rest in the unlocked position of the fail-safe configuration; 
       FIG. 8  is a bottom view of the electric strike of  FIG. 5  in the energized, locked position of the fail-safe configuration; 
       FIG. 9  (prior art) is a side view, partially in phantom and cutaway, of the prior device electric strike as mounted in a door header and keeper engaged with a latch in the top of a door stile; 
       FIG. 10  (prior art) is a side view of the prior device strike of  FIG. 9  in the released position and its keeper hitting the latch as the door is returning to its closed position; 
       FIG. 11  is a side view, partially in phantom and cutaway, of the preferred embodiment of the invention as mounted in a door header in the released position as the door is about to close; 
       FIG. 12  is a side view of the electric strike of  FIG. 11  as the contour of the keeper urges the latch in the top of the door stile to rotate back to its locked position; 
       FIG. 13  is a side view of the electric strike of  FIG. 11  at rest with the keeper engaged within the latch with the door in its fully closed position; 
       FIG. 14  is a perspective and cutaway view of the preferred embodiment of the invention mounted in a door header and a door as it relates to the invention; 
       FIG. 15  is an expanded view of the parts of the preferred embodiment of the invention as seen in FIG.  1  through  FIG. 13 ; 
       FIG. 16  is a side view of another embodiment of the invention, known as a rim panic strike, because it interacts with a rim panic bar or exit device; 
       FIG. 17  is a top view of the rim panic strike; 
       FIG. 18  is a top view of the electric strike of  FIG. 16  mounted on a door frame and holding the latch of a rim mounted exit device mounted on a door; 
       FIG. 19  is a perspective and cutaway view of the rim panic strike mounted on a door frame and a door with an exit device just after the strike has released the door; 
       FIG. 20  is an expanded view of the parts of the electric strike of  FIG. 16 ; 
       FIG. 21  is face view of the “T” strike embodiment without the face plate and showing a cutaway view of the internal parts of the strike in the fail-secure configuration at rest condition; 
       FIG. 22  is the same strike shown in  FIG. 21 , however, in the energized and unlocked condition; 
       FIG. 23  is a perspective view of a prior strike mounted in a door jamb showing the “raceway” cutout and face plate; 
       FIG. 24  is a perspective view of the “T” strike embodiment of the invention with the ramping faceplate that eliminates the “raceway” cutout; 
       FIG. 25  is a top cutaway view of a prior strike mounted in a hollow metal door frame engaging a door latch behind the keeper (the view shows the “raceway” needed for the passage of the latch and the extra space required for the external solenoid); 
       FIG. 26  is a top cutaway view of the “T” strike embodiment of the invention with the ramping faceplate and the smaller profile. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a side schematic view of an electric strike, according to the present invention, as it would be typically mounted in a door header or jamb. This figure shows the external view of the assembly of parts, in its preferred embodiment, comprised of the strike body  1 , a solenoid  2  which is threaded into the body  1  and fastened into place by a lock nut  2 A. A keeper  3  which rotates about an axle  1 E and extends below the body  1  so as to engage a door latch or plate in the top or side of a door. The axle passes through the strike body  1  and is centered therein by retainer clips  1 F at either end. The view also shows the reverse contour  3 A and the relocking lever  3 B features of the keeper. 
     FIG. 2  shows the strike of  FIG. 1  with the keeper  3  (which is spring biased toward the released position) in the released position. 
     FIG. 3  illustrates the preferred embodiment from a bottom view in the locked position. 
     FIG. 4  shows the strike of  FIG. 3  in the unlocked position. 
     FIG. 5  shows a cutaway view of the strike of  FIG. 4  in the locked position. The body  1  of the strike receives the solenoid  2 , which is held in place by locking nut  2 A. Internal to and extending out of the solenoid into the lock body, the plunger  2 B captures a return spring  2 C behind a pin  2 D connecting the plunger  2 B to the actuator  5 . The actuator  5  connects to the actuator plate  6  by means of two locator pins  20  (see  FIG. 15 ) engaging holes  21  in the actuator plate and transfers any linear motion of plunger  2 B to the actuator plate  6 . The actuator plate  6  features two parallel slots  22  (see  FIG. 15 ) which slide over a larger circumference of the pivots  1 B and underneath washers  1 C and retaining clips  1 D. Actuator plate  6  has two sets of driver pins: one set  24  on the top placed inside and equidistant of the pivot slots; and one set  24 A on the bottom placed outside and equidistant of the pivot slots. These pins engage inner or outer holes  25  or  25 A respectively in locking bolt plates  4 . Each locking bolt plate pivots about a pivot  1 B mounted in the housing and extending through a pivot hole  26  (see FIG.  15 ). Sliding motion of the actuator plate  6  is transferred to the locking bolt plates via the driver pins  24  or  24 A, producing equal and opposite moments of torque on the locking bolt plates. As shown in  FIG. 5 , locking elements such as locking bolts  27  extend from the locking bolt plates and rest against a stop means  1 A toward the center of the strike body  1 . 
     FIG. 6  illustrates the invention when an electric current is applied to the solenoid  2  to unlock the keeper  3 . As the electromagnetic force urges the plunger into the body of the solenoid, it compresses the return spring  2 C. After the current is stopped, the mechanism is returned to its prior state by this spring as it decompresses in the first condition ( FIG. 5 ) the locking bolts  4  are at rest at the center of the strike body  1  under the keeper  3 . When the solenoid is energized (FIG.  6 ), the locking bolts are rotated so as to move toward and beyond the edges of the keeper  3 , to the sides of the body  1 , allowing the keeper  3  to rotate to its unlocked position. When the keeper  3  is rotated back to its locked position, and the solenoid  2  is not energized, the locking bolts  4  rotate back toward each other to the center of the strike body  1 . This is the fail-secure configuration. This configuration is defined as the strike being locked when no power is applied to the solenoid. 
   In the second condition (FIG.  7 ), the actuator plate is flipped over and the locking bolts  4  are at rest at the outer edges of the strike body  1 . When the solenoid is energized (FIG.  8 ), the locking bolts  4  are rotated so as to move from the sides of the strike body toward each other and stop at the center of the body  1  which position prevents the keeper from releasing and rotating. When the solenoid is de-energized, the locking bolts  4  rotate back toward the edges of the body  1 . This then allows the keeper  3  to rotate. This is the fail-safe configuration. This configuration is defined as the strike being unlocked when no power is applied to the solenoid. 
     FIG. 9  is a side cutaway view of a prior device  1  shown mounted in a door header  9  with a keeper  3  engaging a latch  13  mounted in a door  10  in the closed and locked position. The illustration also shows the relocking lever  3 B in alignment with the doorstop  9 A. 
     FIG. 10  shows a condition that occurs when the prior device strike is in the unlocked position and the door is closing after the exit device had been activated. The lobe of the prior device keeper  3  comes into contact with the latch and causes enough friction to hold the door open and unsecured. 
     FIG. 11  is a side cutaway view of the preferred embodiment of the present invention having the strike  1  mounted in a door header  9  and showing the keeper  3  as it begins to engage a latch  13  mounted in a door  10  which is closing. The keeper&#39;s relocking lever  3 B comes into contact with the inside edge of the door  10  and starts the keeper to rotate about its axle  1 E toward its locked position. 
   At the point where the keeper rotates and comes into contact with the latch (FIG.  12 ), the concave contour  3 A on the lobe allows the keeper to enter the latch  13  and ramps out the latch  13  towards its locked position as it rotates. When the door fully closes ( FIG. 13 ) and the keeper  3  is fully rotated back to its locked position, the door latch  13  has also been fully rotated back to its locked position and the door is secured. 
     FIG. 14  is a perspective cutaway view showing the relationship of the door  10 , latch  13 , header  9 , and strike  1 ,  2 ,  2 B mounted in the header with the keeper  3 ,  3 A,  3 B. The keeper is in the rotated (biased) or unlocked position as it would be after the solenoid  2 ,  2 A had been energized and the door had been released by the strike and opened by a user. 
     FIG. 15  is an exploded perspective view of the component parts of the preferred embodiment, which illustrates the different location of the drive, pins on the two sides of the actuator plate  6  and  6 A. The view also shows the three holes in the locking bolts  4 : the center hole being the pivot hole; and the two outer holes to accommodate the drive pins on either side of the actuator plate  6 . The parts in the group identified by number  8  are the parts that would comprise a latch bolt monitoring option. 
     FIG. 16  is a side view of the rim panic strike embodiment of the invention showing the mounting hole configuration of the body  1 , the keeper  3  and the latch bolt monitoring sensor plate  8 B as it sits inside the keeper. 
     FIG. 17  is a top view of the invention of  FIG. 16  which shows the actual thickness of the strike, the keeper  3  as it extends out of the strike body  1 , the keeper pivots  3 C, the latch bolt monitoring sensor plate  8 B and the cover  7 . 
     FIG. 18  is a top view of the strike of  FIG. 16  mounted in typical fashion on a door jamb  9  and holding the latch  13  of an exit device  11  with its push bar  12  mounted on a door  10 . The standard roller latch  14  is shown (removed) as a reference. 
     FIG. 19  is a perspective cutaway view of the invention as seen in  FIG. 18  showing the door after being released from the strike. 
     FIG. 20  is a perspective blow up view of the rim panic strike embodiment of the invention. The actuator plate  6 ,  6 A is similar to the preferred embodiment, but the locking bolts plate  4  are shaped differently to accommodate the different keeper  3  design. The keeper assembly  3 A,  3 B, actuator arm  5  and locator pins SA, latch bolt monitoring assembly  8 , solenoid assembly  2 ,  2 A,  2 B,  2 C, strike body  1 , and cover  7  are all different as well in this embodiment, but are functionally equivalent to the elements of the preferred embodiment. 
     FIG. 21  shows a third embodiment in the form of a small format 161 prep, “T” strike and/or a larger ANSI format electric strike. This diagram illustrates the changes in the shape of the aforementioned component parts and their relational position to each other. The features and operation of the parts are functionally equivalent to the preferred embodiment. This view details the strike body  1  as it contains the relevant parts: solenoid assembly  2 ,  2 A,  2 B,  2 C which is comprised of the solenoid housing and coil  2  the fastener  2 A the plunger  2 B the plunger spring  2 C; the keeper  3  in dotted lines to reveal the position of the locking bolts beneath and its two pivots  3 C; the locking bolts  4 ; the actuator  5  and locator pins  5 A; and the actuator plate  6 . This figure shows the strike at rest in the fail-secure configuration (locked). 
     FIG. 22  shows the same strike of  FIG. 21  in the energized state (unlocked). This condition occurs when an electric current is applied to the leads of the solenoid  2 . Electromagnetic force urges the plunger  2 B toward the body of the solenoid  2  against the force of the return spring  2 C and causes linear movement of the actuator  5  by means of a connecting pin  2 D. This linear movement is translated to the actuator plate  6  by means of the locator pins  5 A fitting into the holes in the actuator plate  6 , causing it to slide against the pivots  1 A. The linear movement of the actuator plate is translated into equal and opposite moments of torque exerted upon the two locking bolts  4  by the drive pins in the actuator plate  6  as they rotate in holes in the locking bolts  4 . This rotation results in the keeper being free to be pushed into the body of the strike and out of the way of the latch as the door is pulled open by the authorized individual&#39;s hand. After the latch passes by the keeper  3 , and after an appointed time, usually 5 seconds, the electric current is terminated by the access control computer and the keeper returns to its locked condition by the keeper springs  3 A. This allows the locking bolts  4  to rotate back under the keeper as urged by the plunger spring  2 C through the actuator  5  and actuator plate  6 . The length of its slots limits the travel of the actuator plate  6  as it moves over the pivots  1 A. Because it is loosely held in place by the pivot washers  1 B and retainer clips  1 C, the actuator  5  is captured under the actuator plate  6 . When the user needs to change to the fail-safe configuration, the actuator plate  6  is flipped over and re-secured by the plate washers  1 B and clips  1 C. A second and opposite set of drive pins on the actuator plate  6  is introduced into a second and oppositely located set of holes in the locking bolts. This results in equal and opposite moments of torque exerted on the locking bolts as they rotate about the pivots  1 A, and thereby, results in the opposite rest and rotated position of the locking bolts while the solenoid is energized. 
   FIG.  23  and  FIG. 24  are perspective drawings that show the difference between the prior device and faceplate and the present invention and the ramping faceplate. It should be noted on  FIG. 24  the scalloped out section on the ramp  2 . This channel allows the auxiliary latch to fully extend after the latch passes over the keeper  3 . Once both the auxiliary latch and main latches have fully extended, they will ramp in together and ride over the lip of the strike, clear the jamb altogether, and allow the door to fully open. 
   FIG.  25  and  FIG. 26  show the same objects of FIG.  23  and  FIG. 24 , but show them in a top phantom and cutaway view. 
   These various embodiments come within the scope of the present invention. The inventor&#39;s preferred embodiments, which are described in detail herein, are exemplary of all possible embodiments which practice the spirit of the present invention. The discussion of these specific embodiments should not be construed as limiting the scope of the appended claims. For example, the invention could be made having a dedicated configuration, rather than being made to be field configurable. In view of this, it is understood that the above description is illustrative rather than limiting. 
   Similarly, although the preferred embodiment has a pair of locking elements such as the locking bolts, it should be appreciated that the principle of the invention could be applied to embodiments in which there is only one pivoting locking element which pivots behind or away from the keeper.