Patent Application
20080307837
The present subject matter relates to an enclosure locking latch mechanism. More particularly, the present subject matter relates to a latch mechanism that may be configured to provide either a slam latch or dead bolt latch type action, and used with either new (oem) equipment or retrofit applications. In either such configuration, an electric motor may be included within a latch housing and operative to open or unlock the latch.
Many occasions arise that require electronic access control of different types of cabinets, entryway doors, carts, tool boxes, and other types of boxes, hereafter regardless generally of their compositions, materials, or configurations collectively referred to as an enclosure or cabinet. Such enclosures or cabinets may be provided with doors and/or may also include drawers.
The need for access control usually arises from the lack of security often provided by typical lock and key mechanisms. For example, a mechanical key may be lost or stolen. Once such a lost or stolen key has been surreptitiously obtained by an unauthorized individual, such individual in possession of such key may easily access the secured enclosure to either steal its contents or, as in the case of secured medical records or other confidential documents, view its contents. Further, when such enclosures or cabinets are accessed, there is typically no record that it has been accessed, let alone who accessed it or when such access took place.
Such shortcomings of keyed mechanical locks have contributed to the creation of the specialized field of electronic access control.
Typically, electronic access control may correspond to a three part system, including, for example: (1) a credential reader, (2) a microprocessor based control circuit, and (3) an electronic latch to mechanically open or unlock the enclosure being secured by the access control system.
Credential readers may include, but are not limited to: keypads, magnetic stripe card readers, proximity card readers, “ibuttons,” smart card readers, and/or bar code card readers. In the recent past, there has been significant progress in the field of biometrics that includes, but is not limited to, the ability to reliably read and discern an individual's fingerprints, handprints, and retina and/or facial features.
Generally speaking, credential and/or biometric readers convert their applicable credential or biometric features, respectively, into a binary number. A microprocessor based system then reads and analyzes such binary number. Such systems are typically either standalone (attached to the reader) or networked (attached to many readers). Typically, they may read the binary number that corresponds to the potential entrant's credential or biometric features and compare it to a list of approved binary numbers. In such fashion, the microprocessor based system determines if the potential entrant has the right to access the enclosure or cabinet being secured by the access control system.
If the microprocessor based system determines that the subject credential or biometric feature under consideration is valid, access is granted to the enclosure. Typically, such is accomplished by the microprocessor turning on an electronic control circuit corresponding to a solid state devices or relays which in turn provide a useable electrical voltage to open an electronic latch mechanism. There are generally speaking two primary styles of electronic latch mechanisms: slam latches and dead bolt latches.
Slam latches have a spring loaded locking feature or slam bolt, allowing for the door of the enclosure to be locked by simply pushing or “slamming” the door closed. The slam bolt is easily pushed into the latch body and is provided with a spring return.
Typically, one side of such a slam bolt is provided with a cam surface. The slam latch in general terms is mounted to the interior door surface of a given enclosure such that the cam surface strikes the enclosure frame, which in turn drives the latch's slam bolt into the latch body as the door is closed. Such action charges a return spring. Typically, the inside of the enclosure frame is provided with a locking surface against which the slam bolt locks. Once the enclosure door is closed, the charged return spring extends the slam bolt, locking the enclosure.
Dead bolt latches utilize a fixed dead bolt without means of a spring return. Such types of latches instead require the electronic control circuit to actuate a motor or solenoid to alternately retract and/or extend the dead bolt in order to provide the locking (or unlocking) action. In other words, a locking action is not “automatic” when the enclosure door is closed.
The dead bolt in the above-referenced type of latch mechanism is typically provided with a square or rectangular end (though alternatives may be practiced). A latch utilizing such type of bolt is generally speaking in at least one sense more secure than a slam latch because it needs to receive a credentialed (i.e., authorized) signal in order for the dead bolt to be retracted. In comparison, the bolt of a slam latch may simply be pushed in. Such “pressing in” action can be done by a thief after employing dishonest means to access the enclosure being secured by the slam bolt. However, the corresponding adverse or negative aspect of the dead bolt type latch is that an enclosure door cannot simply be slammed closed. The latch must receive a signal from the access control system to extend the dead bolt at the correct time.
It is a fairly common occurrence in the field that such latches will have some locking force applied to them in a direction which is perpendicular to the bolt surface. Such force can be the result of a variety of influences and/or conditions, for example, improperly installed latches, racked or twisted cabinets, swollen door materials (for example, wood), articles inside the enclosure falling against the inside of the door, and/or from an enclosure being “over stuffed”. Such a “pre-load” on the latch bolt may in some instances be relatively significant, for example, on the order of several pounds.
The prime mover in the types of latches presently addressed are typically either a solenoid or a motor/gear train combination. Solenoid based latches having equal strength to a given motor/gear train based latch are significantly larger and heavier than such “equivalent” motor/gear train design. Latches constructed in accordance with the present subject matter are motor based.
Motor/gear train based slam latches present a design challenge in that during the slam action, the locking bolt needs to be disconnected from the gear train. If such aspect is not properly provided or accomplished, it may have a detrimental affect on the reliability of the gear train and latch.
It is further desirable from a manufacturing and business point of view to have a latch that is easily assembled as either a slam latch or a dead bolt latch configuration, depending on the simple addition/deletion of a minimal number of parts.
While various implementations of enclosure locking mechanisms have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.
The present subject matter is directed to a motorized latch mechanism. More particularly, the present subject matter is directed to a motorized latch mechanism which may be embodied as either a slam latch or a dead bolt latch with minimal changes in the number of parts employed in the latch mechanism, and which may be used either on new (oem) equipment or in retrofit applications. By such minimized parts changes, differing embodiments of the present subject matter may be provided, resulting in the selection of differing latch bolt behavior in the extended or locked state.
A slam latch embodiment of the present subject matter preferably includes a spring loaded locking bolt with an angled cam surface. Such slam bolt is easily pushed into the main latch body and is provided with a spring return. The standard mode of operation for such type of latch is to have the cam surface of the slam bolt contact a metal strike on the enclosure frame during the door close action. The present motorized latch is typically mounted to the moving door of the enclosure. Such striking action causes the slam bolt to enter the main latch body, compressing (i.e., charging) a return spring. Once the slam bolt has entered the main latch body, the enclosure door can close and the return spring can re-extend the slam bolt, which in turn locks behind the enclosure frame.
The action of the dead bolt latch embodiment of the present subject matter is similar except that the dead bolt is not spring loaded and requires the action of the motor to extend the dead bolt. The present dead bolt latch design provides a relatively higher level of security as the locking bolt is never disengaged from the gear train and thus cannot simply be pushed into the latch body. Such additional level of security nonetheless comes at the price of inconvenience as it requires the user to “tell” the system to extend the dead bolt, whereas the slam latch simply requires the user to “slam” the door.
The present subject matter corresponds to a latch mechanism that, with the simple addition or removal of a minimal number of parts can be assembled as either a slam latch or a dead bolt latch. The provision of such a convertible latch mechanism is desirable from a business perspective as only one set of latch parts needs to be tooled and maintained. Further, it is desirable from a manufacturing point of view as only one assembly line must be set up and maintained.
Although from a business standpoint, it is not necessarily expected for the latch mechanism described herein to be field changeable from one latch type to the other, such a field conversion is structurally possible and presents yet another significant benefit of the present subject matter.
A motorized latch constructed in accordance with the present subject matter may be provided with an electrical connector for connecting the motorized latch to an access control system. As referenced above, access control systems require a user to present a credential to a credential reader. Credential readers which may be practiced with the present subject matter include for example, but are not limited to, keypads, magnetic stripe card readers, proximity card readers, “ibuttons,” smart card readers, and/or bar code card readers. In addition to credentials, the access control system may also (or alternatively) be provided with the ability to read an individual's biometric data including, but not limited to, fingerprints, hand prints, and retina and/or facial features. All such variations may be practiced in conjunction with embodiments of the present subject matter.
In either case, the credential, including biometrics, is read and checked against one or more valid credentials. If the access control system decides that the credential is valid, it will “tell” the motorized latch to open. Typically, such may be accomplished by a solid state control circuit providing a low voltage electrical signal to the latch. Such electrical signal is transmitted through related wiring and connectors to the electrical connector on the motorized latch.
In the present exemplary embodiments, such an electrical connector is provided with terminals and wiring connecting it to a motor. The shaft of such exemplary motor is connected to a gear train, consisting of a plurality of gears, which acts to both reduce the speed of the motor while increasing its output torque, as well understood by those of ordinary skill in the art.
The end of such exemplary gear train may be connected to an output cam pin. Such cam pin engages a tab on one end of a slide. The opposite end of the slide may also have a tabbed feature which in turn engages the latch bolt.
In the present slam latch configuration, as the bolt is retracted, a return spring is charged. There is an additional tab on the slam bolt which contacts an electrical switch when the slam bolt is fully retracted. Such switch (which may be presently referred to as a latch retracted feedback switch) is electrically connected to the same access control system through the same wires, connectors, and the like as is the motor. When the latch retracted feedback switch is closed, by the slam bolt reaching the retracted position, the access control system preferably turns off the motor. Such preferred present operation allows time for the entrant to open the enclosure door.
After some time, which per the present subject matter may be adjustable by the latch owner, the access control system turns the motor back on. The output cam pin then rotates off of the tabbed feature on the slide, allowing the slide to move freely. The charged return spring then pushes the slam bolt out of the main latch body, pulling the slide with it. Such action also preferably per the present subject matter disengages the slam bolt from the latch retracted feedback switch so that the switch is now open. The access control system “sees” the switch open and, therefore knows that the latch's slam bolt has released, and it turns the motor off. As previously described, the bolt is again in the extended, spring loaded state and is easily pushed back into the main latch body when the cam surface on the slam bolt strikes the enclosure frame during the door closing action.
By contrast, when the bolt is retracted in the dead bolt latch configuration of the present subject matter, there is no return spring being charged. The dead bolt latch is also provided with the present latch retracted feedback switch. However, in addition to such switch, the dead bolt latch is provided with a second switch, the presently referenced latch extended feedback switch. Such latch extended feedback switch in essence “tells” the present access control system that the dead bolt is fully extended. Such information from the latch extended feedback switch is significant as the dead bolt does not spring-return to a fixed position in the dead bolt latch configuration. The access control system needs to know when the dead bolt is fully extended in order to turn off the motor at the correct time.
While the dead bolt retract action is identical to that of the slam latch design, that of the latch extend differs greatly, per present features. When the output cam pin rotates off the tabbed feature on the slide, the slide is still allowed to move freely. However, since there is no return spring, the dead bolt (although now uncoupled from the gear train) does not move. As the motor continues to run, the cam pin contacts the front tab of the slide. In the dead bolt latch configuration, the slide is preferably provided with an additional dead bolt pin. As the slide is pushed forward, the dead bolt pin on the slide in turn pushes the dead bolt out of the latch body. Such action also removes the dead bolt from closing the latch retracted feedback switch and causes it to instead close the latch extended feedback switch. The access control system “sees” the latch extended feedback switch close, and therefore knows that the dead bolt has fully extended, and further therefore turns the motor back off. The dead bolt is now fully extended and cannot be pushed back in, as it is being blocked by the dead bolt pin on the slide and in turn blocked by the output cam pin on the end of the gear train. The dead bolt extension action must occur after the enclosure door is in the closed position. If the extension action is performed before the door is closed, the dead bolt will have to be retracted again before closing.
In accordance with the present subject matter, the exemplary four parts that with their respective addition or deletion allow the latch to be easily alternatively assembled in either of the slam or dead bolt configurations are preferably the return spring, the spring guide, the dead bolt pin, and the latch extended feedback switch.
One present exemplary embodiment relates to a convertible latch having a housing, a latch bolt, a drive mechanism, and at least one electrical switch. Such latch bolt is preferably mounted at least partially within such housing for selected alternate extension from such housing and retraction into such housing. Such exemplary drive mechanism is preferably configured to selectively retract such latch bolt into such housing, while such at least one electrical switch is preferably mounted within such housing and positioned such that such switch is operated by such latch bolt upon retraction of such latch bolt into the housing.
In exemplary variations of the foregoing, such drive mechanism may comprise an electrically operated drive mechanism including an electrically operated motor and an associated drive mechanism output. In some embodiments, such drive mechanism output may include a gear train, an output cam, and an output cam pin. In still further present alternatives, an electrical connector may be mounted to such housing, so as to provide electrical connections to an electrically operated drive mechanism and an electrical switch.
In still further present exemplary embodiments, a convertible latch kit may be provided including various components for selective assembly. Such a present exemplary kit may include a housing, an electrically operated drive mechanism mounted in such housing and having an associated drive mechanism output, a slam bolt configured to be mounted in such housing and to be retracted by such drive mechanism output, a spring configured to be cooperatively engageable with such slam bolt to provide a force thereto in the direction of extending such slam bolt from such housing, and a dead bolt configured to be mounted in such housing and to be selectively alternately retracted and extended by such drive mechanism output.
In a still further present exemplary embodiment, a convertible motorized latch may be configured in either of a slam latch or a dead bolt latch configuration, for use with a cabinet of the type having an alternately openable and closeable door. Such latch may comprise a latch housing, configured to be supported on the a door of a cabinet, on the inside of such cabinet; a latch bolt associated with such latch housing, and configured for alternately assuming retracted and extended positions relative to such housing; an electric motor contained within such latch housing, and operative when actuated to unlock such latch bolt by moving it into a retracted position thereof; a geared output incorporated within such latch housing and associated with such electric motor so as to provide reduced speed and increased torque therefrom; and an electrical feedback switch for signaling latch bolt retraction.
Still further, certain present embodiments may equally relate to corresponding methodologies. One such exemplary methodology relates to providing controlled access to a cabinet of the type having an alternately openable and closeable door for unlocking and locking thereof. Such exemplary method may comprise providing a convertible latch kit including components for selective assembly (such as the above referenced example, thereof, determining whether such cabinet is of the type having an associated strike plate supported on a frame thereof, for use with a slam bolt configuration, or of the type having a recessed area formed in a frame thereof, for use with a dead bolt thereof; depending on such determination, selecting accordingly either of such slam bolt or dead bolt, respectively, for inclusion in such housing; and mounting such housing in such cabinet, supported on the door thereof and positioned so that the included bolt of such housing is interoperative with the frame of such cabinet for alternate locking and unlocking of the cabinet door.
Such exemplary method may further include additional aspects, forming yet further present methods. For example, additional steps may include mounting an electrical connector in such housing and configured to provide electrical connection to said electrically operated drive mechanism; while also providing said drive mechanism output with a gear train, an output cam, an output cam pin, a slide engageable with either of said slam bolt or said dead bolt, and a slide tab coupled to said slide and configured for engagement with said cam pin. Still further potential alternatives may include mounting at least one electrical switch in such housing and coupled to said electrical connector so as to sense movement of one of said slam bolt and said dead bolt mounted in said housing. Yet additional steps may include further mounting a second electrical switch in such housing and coupled to said electrical connector so as to further sense movement of one of said slam bolt and said dead bolt mounted in said housing. Still other aspects may include providing an external access control device attached to said electrical connector, for controlling said electrically operated drive mechanism for alternately unlocking and relocking said door through actuation of said drive mechanism, said control device including an automatic pre-programmed time delay for relocking said door after unlocking thereof.
Additional objects and advantages of the present subject matter are set forth in, or will be apparent to, those of ordinary skill in the art from the detailed description herein. Also, it should be further appreciated that modifications and variations to the specifically illustrated, referred and discussed features, elements, and steps hereof may be practiced in various embodiments and uses of the present subject matter without departing from the spirit and scope of the present subject matter. Variations may include, but are not limited to, substitution of equivalent means, features, or steps for those illustrated, referenced, or discussed, and the functional, operational, or positional reversal of various parts, features, steps, or the like.
Still further, it is to be understood that different embodiments, as well as different presently preferred embodiments, of the present subject matter may include various combinations or configurations of presently disclosed features, steps, or elements, or their equivalents including combinations of features, parts, or steps or configurations thereof not expressly shown in the figures or stated in the detailed description of such figures. Additional embodiments of the present subject matter, not necessarily expressed in the summarized section, may include and incorporate various combinations of aspects of features, components, or steps referenced in the summarized objects above, and/or other features, components, or steps as otherwise discussed in this application. Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the remainder of the specification.
A full and enabling disclosure of the present subject matter, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
a and 5b are cutaway views similar to present
a illustrates a partial cutaway, side view of the exemplary slam latch subject matter of present
a, 12b, and 12c illustrate respectively various exemplary aspects of the slam action of an exemplary slam latch constructed in accordance with the present subject matter;
a and 17b are cutaway views similar to present
a illustrates a partial cutaway, side view of the exemplary dead bolt slam latch subject matter of present
a and 24b illustrate respectively various exemplary aspects of the dead bolt action of an exemplary dead bolt latch constructed in accordance with the present subject matter, including but not limited to, illustration of the output cam pin beginning to extend the exemplary slide and dead bolt, per present subject matter;
Repeat use of reference characters throughout the present specification and appended drawings is intended to represent same or analogous features, elements, or steps of the present subject matter.
As discussed in the Summary of the Invention section, the present subject matter is particularly concerned with a motorized latch mechanism that may be variously embodied as either of a slam latch or a dead bolt latch.
Selected combinations of aspects of the disclosed technology correspond to a plurality of different embodiments of the present subject matter. It should be noted that each of the exemplary embodiments presented and discussed herein should not insinuate limitations of the present subject matter. Features or steps illustrated or described as part of one embodiment may be used in combination with aspects of another embodiment to yield yet further embodiments. Additionally, certain features may be interchanged with similar devices or features not expressly mentioned which perform the same or similar function.
Reference will now be made in detail to the presently preferred embodiments of the subject motorized latch mechanism. Referring now to the drawings,
As illustrated in present
Exemplary door 8 of such exemplary embodiment may be secured in its determined closed position by the interaction of slam bolt 2 and strike 12 at a point 14. Strike 12 may be secured to cabinet frame 9 with screws 13a, 13b or other suitable means.
Exemplary motor 15 as representatively illustrated is contained by a cavity within housing 3, and is provided with exemplary pinion gear 19 which is pressed onto shaft 18 thereof. Pinion gear 19 in turn (in this exemplary embodiment) drives bevel gear 21 which rotates on a shaft 20a bounded by slotted walls in housing 3. Bevel gear 21 in turn drives a series of various spur gears 22a, 22b, 22c, 22d, and 23. Gears 22b and 22d also rotate on shaft 20a. Gears 22a, 22c, and 23 rotate preferably on shaft 20b, which is also bounded by slotted walls in housing 3. Such overall gear train arrangement collectively provides reduced speed and increased output torque from exemplary motor 15. It is to be understood that variations to such gear train may be practiced per present subject matter. In other words, the present subject matter is not intended as being limited to particular configurations of gear trains.
In an exemplary embodiment, motor 15 may be controlled by a microprocessor based access control system. Such access control system may be electrically connected to slam latch 100 through electrical connector 6. It should be appreciated, however, that other types of control systems, including but not limited to, a simple manually operated electrical switch and power supply could also be used to selectively actuate motor 15.
In the event that an access control system is employed, and upon presentation of a valid credential or biometric to the access control system, power may be supplied to exemplary motor 15 by solid state motor controls and/or electrical relays through connector 6 and the related wiring, as well understood by those of ordinary skill in the art without additional discussion. Electrical connector 6 is connected to motor 15 through motor wires 16a, 16b, which may be soldered or otherwise secured to motor 15 terminals 15a, 15b. An electrical interference suppression device 17 may also be connected to terminals 15a, 15b. In an exemplary embodiment, electrical interference suppression device 17 may correspond to a capacitor. As motor 15 is energized, it rotates gear 19, which in turn rotates gears 21, 22a, 22b, 22c, 22d, and 23. The final gear of the gear train, gear 23, is coupled with output cam 24, which is provided with output cam pin 25, all as will be understood by those of ordinary skill from the disclosure herewith.
More particularly,
a illustrates a partial cutaway, side view of the exemplary slam latch subject matter of present
More particularly,
Motor 15 will remain off per present subject matter during an open delay period pre-programmed into the access control system. In
At the expiration of such pre-programmed delay period in the access control system, motor 15 is once again energized.
a, 12b, and 12c illustrate respectively various exemplary aspects of the slam action of an exemplary slam latch constructed in accordance with the present subject matter. More particularly, such
More specifically,
c illustrates that the action of slam bolt 2 has not affected the position of slide 26. Tab 2a of slam bolt 2 is disengaged from slide tab 26a, thereby creating the indicated gap 41.
The exemplary cabinet per the present
As represented by present
Motor 15 of the second exemplary embodiment of the present subject matter may also be controlled by a microprocessor based access control system. The access control system is electrically connected to dead bolt latch 300 through electrical connector 6. Again, it should be appreciated that other types of control systems may be employed in place of or in addition to the mentioned microprocessor based access control system.
Upon a valid credential or biometric being presented to the access control system, power is supplied to motor 15 by solid state motor controls and/or electrical relays through connector 6 and the related wiring. Electrical connector 6 is connected to motor 15 through motor wires 16a and 16b which are soldered or otherwise appropriately connected to motor 15 at terminals 15a, 15b. Further, such embodiment of the present subject matter may also be provided with electrical interference suppression device 17, connected to terminals 15a, 15b which may, as in the first embodiment, correspond to a capacitor. Upon energization, motor 15 rotates gear 19, which in turn rotates gears 21, 22a, 22b, 22c, 22d, and 23. The final gear of the gear train, gear 23, is coupled with output cam 24 which is provided with output cam pin 25.
a and 19b illustrate that dead bolt latch 300 is also provided with latch retracted feedback switch 32, the state of which is constantly monitored by the access control system. Latch retracted feedback switch 32 is located adjacent posts 33a and 33b of housing 3, and is electrically connected to electrical connector 6 by internal wires 34a and 34b. Dead bolt 43 is considered in its presently defined fully retracted position when actuator 35 of the latch retracted feedback switch 32 is depressed by tab 43b on the underside of dead bolt 43 at contact point 36. Motor 15 is then turned off by the access control system.
Dead bolt latch 300 is during such condition in its presently defined unlocked or open state. The latch will remain in such state until closed by the access control system, typically after receiving an additional input from the entrant (that is, the authorized person seeking to access the enclosure).
In
In the dead bolt latch embodiment of the present subject matter, dead bolt 43 is fixed to the present gear train and thus not capable of slamming shut as in the slam latch embodiment. It is therefore necessary for door 8 to be closed (as represented in present
a and 24b illustrate respectively various exemplary aspects of the dead bolt action of an exemplary dead bolt latch constructed in accordance with the present subject matter, including but not limited to, illustration of the output cam pin beginning to extend the exemplary slide and dead bolt, per present subject matter. More specifically,
Continuing reference to present
While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is intended by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.
This application claims the benefit of previously filed U.S. Provisional Patent Application entitled “CONVERTIBLE MOTORIZED LATCH,” assigned U.S. Ser. No. 60/934,308, filed Jun. 12, 2007, and which is hereby incorporated herein by reference in its entirety for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 60934308 | Jun 2007 | US |
