The invention relates to a door strike used to prevent the opening of an associated door when the door strike has been heated to an elevated temperature. More particularly the door strike incorporates a thermally responsive element within its construction which, in response to a being at a temperature of at least about 1000° F. operates to incapacitate the associated door from being opened in its usual manner. In a preferred embodiment the door strike is an electrically operated door strike, but may be used in other configurations of locking hardware.
In general, prior art strikes comprise a single solenoid which has a winding of a conductor which, when electrically energized, actuates an armature which has a locking member connected thereto and biased by a spring so that the locking member prevents pivoting of the keeper unless the solenoid is electrically energized. To keep the energizing current low, the biasing spring usually has a force which is only slightly more than the force required to return the locking member and the armature to their locking or unlocking positions. It is also known in the art to use an air actuated piston and cylinder assembly with the piston connected to the locking member to actuate the locking member.
In conditions when a fire is present in a building, it may be advantageous to have a feature wherein doors which are exposed to elevated temperature conditions are automatically held in a locked condition as such may be used to retard the spread of a fire, particularly between adjacent spaces separated by the door. Where a fire condition exists in one of these spaces (i.e., a room, chamber, hallway at the like) and entry into this space would be hazardous due to a fire or smoke conditions being present in that space, inadvertent entry into that space is retarded by holding the door separating these spaces in a locked condition, even if a solenoid (or air actuated piston and cylinder assembly) is actuated. Such a feature would aid in containing the fire and/or smoke condition separate from the adjacent spaces where a fire and/or smoke condition does not exist, the latter would be a safe space for occupants of the building who should seek a rapid entry from the building. It would also be advantageous that such a feature would also be a reversible feature, that is to say that when the elevated temperature ceases to exist in the building then, the door could be opened in its usual manner; in particular that the actuation of the solenoid (or air actuated piston and cylinder assembly) of the door strike would permit for the associated door to be opened.
Door strikes which are responsive to thermal conditions are known to the art. For example in U.S. Pat. No. 8,132,833 to Schneckenburger is disclosed a door strike apparatus which includes an intumescent material, which relies upon a chemical change in the material upon exposure to high heat. Upon exposure of the door strike apparatus to an elevated temperature, the intumescent material is heated and expands to a larger volume which acts to fill internal voids present within the door strike apparatus and between certain of the moving parts thereof which incapacitates the door strike apparatus from a normal mode of operation. The use of the intumescent material is not reversible in operation, namely in order to restore the door strike apparatus to its usual mode of operation the door strike apparatus is necessarily removed, disassembled, cleaned, reassembled and reinstalled into the door frame.
The present invention addresses and overcomes various shortcomings in the prior art.
In a first aspect of the present invention there is provided locking hardware which prevents the opening of an associated door when the locking hardware has been heated to an elevated temperature of at least about 1000° F., preferably when the door strike is at higher temperatures such as are present during a fire in a building structure.
In a second aspect of the present invention there is provided a door strike, preferably an electrically operable door strike, which prevents the opening of an associated door when the door strike has been heated to an elevated temperature of at least about 1000° F., preferably when the door strike is at higher temperatures such as are present during a fire in a building structure.
In a third aspect, there is provided locking hardware of the first aspect, or a door strike of the second embodiment, wherein the locking hardware and/or door strike is operable in a reversible manner, namely when the locking hardware and/or door strike is exposed to an elevated temperature (e.g., 1000° F. or higher) it prevents its associated door from opening while the elevated temperature condition exists, even if the actuating mechanism (i.e., a solenoid, or air actuated piston and cylinder assembly) is operated or engaged, but when the elevated temperature of the locking hardware and/or door strike is diminished and the elevated temperature condition of the door strike ceases to exist then, the associated door may be opened in its usual manner, viz the actuation of the solenoid (or air actuated piston and cylinder assembly) of the locking hardware and/or door strike permits for the associated door to be opened.
In a fourth aspect of the invention there is provided a method for controlling the undesired spread of a fire or smoke between adjacent spaces separated by the door wherein a fire or smoke condition exists in at least one of these spaces, the method comprising the step of providing a locking hardware and/or door strike according to any of the foregoing aspects of the invention for use with the door.
These and further aspects and features of the present invention will be described in further detail in the following description of which the drawing figures form an integral part thereof.
In the drawing figures, like elements are identified by common reference numerals and/or letters within the several drawing figures. References to elements of the door strike are to be understood as being also relevant to locking hardware which is not necessarily part of a door strike for use with doors, but which may be used with other openable parts or structures, e.g., windows, panels, etc.
Referring generally now to the drawings,
Further visible is a biased locking lever 19 including a latch section 19f which interacts with a long arm 18 having a latch hook end 18a. The locking lever 19 includes a pivot bore 19a at one end thereof and at the opposite end thereof a pin bore end 19b within which is mounted a locking shaft 19c. The locking lever 19 is rotatably mounted upon a part of support wall 16b via a pivot pin 22 which passes through the pivot bore 19a of the locking lever 19. Advantageously the pivot pin 22 also engages a part of the locking lever spring 11 which biases the locking lever 17 to pivot towards the solenoid 20 and inwardly towards the keeper 14. When the solenoid rod 20b is caused to move outwardly from the interior of the solenoid coil 20a when it is energized, a solenoid rod end 20c contacts the locking shaft 19c causing it to move away from the solenoid coil 20a as well as the keeper 14 against the bias of the locking lever spring 11 by concurrently pivoting the locking lever 19. When the solenoid coil 20a is de-energized the solenoid rod 20c is retracted into the solenoid coil 20a, and the force of the locking lever spring 11 returns the locking lever 19 to its prior “locked” position as is more clearly seen in
The door strike 10 may includes further elements useful in assembly and retaining parts thereof such as fasteners 24 which may be screws as depicted, but which may be other fasteners providing a similar function, i.e., pins, rivets or adhesives, as well as supporting plates 25 and an assembly cover 12 which may advantageously be used to encase one or more elements of the door strike 10. Advantageously the assembly cover 12 obscures the long arm 18 and the locking lever 19 from view and retards easy access to these elements so to diminish tampering or interference with the operation of these elements. Such an anti-tampering benefit enhances the overall reliability of the electrically operable door strike at all thermal conditions.
The door strike 10 may be installed in a left hand door configuration or a right hand door configuration, as the door strike 10 is effective in both an “upright” configuration as per
In a certain embodiment of the invention the thermally responsive element is irreversibly deformable, such that when heated to an elevated temperature and assumes a second configuration, it does not revert to its first, initial configuration when cooled. i.e., to about room temperature (about 68° F. (20° C.)). Preferably however the thermally responsive element is reversibly deformable, that is to say it assumes a second configuration when heated to an elevated temperature from its first configuration, i.e. an initial configuration when the thermally responsive element is at about room temperature, but when cooled from the elevated temperature to about room temperature it substantially reverts to its first configuration. While an elevated temperature may be any which is above about room temperature, preferably such an elevated temperature is a temperature of at least about 1000° F. (538° C.), preferably at least about 1200° F. (649° C.), still more preferably at least about 1400° F. (760° C.) or even higher. The change in configuration of the thermally responsive element from the initial or first configuration to its heated or second configuration, causes at least part of the a thermally responsive element to interact with one or more further parts of the door strike, preferably the electrically operated door strike so to prevent or retard the door strike from operating in its usual manner, thereby retarding or denying the associated door from being opened in its usual manner, i.e., by pushing or pulling the door.
In a particularly preferred embodiment the thermally responsive element, when in its heated configuration, interferes with one or more mechanically displaceable elements of the door strike such that even if an internal solenoid, (or actuated piston and cylinder assembly is operated, the door strike remains in its locked state.) Only when the thermally responsive element has been sufficiently cooled from a heated or elevated temperature, it may revert back to its first configuration and thereby permit the electrically operable door strike to operate in its usual manner.
Returning now to
As is most readily seen from
As noted previously the thermally responsive element 30 may operate in a reversible manner, or it may operate in an irreversible manner. In the former the thermally responsive element 30 ultimately reverts to its first configuration from its second configuration when cooled, e.g. to about room temperature (approx. 68° F.). In this manner, the thermally responsive element 30 undergoes reversible deformation due to being heated to the elevated temperature, and thereafter being cooled to about room temperature. In the latter the thermally responsive element 30 changes from its first configuration and assumes a second configuration when heated to an elevated temperature, but does not revert to its first configuration when cooled, e.g. to about room temperature. In this manner, the thermally responsive element 30 undergoes permanent deformation due to being heated to the elevated temperature. The latter, i.e., permanently deformed thermally responsive element 30 would require that the door strike 10 be removed and the thermally responsive element 30 replaced with a new such element and the door strike 10 reinstalled before allowing the associated door to be returned to normal usage.
Any material of construction which responds in the manner discussed above may be used in the fabrication of a suitable thermally responsive element 30. Preferably the thermally responsive element 30 incorporates into its construction a thermally responsive metal element which would provide such an operation as described. Bi-metallic elements are advantageously used as or forming parts of thermally responsive elements, it only being require that they respond to elevated temperatures as described herein. A non-limiting example of such a thermally responsive metal include those sold as “Polymet” materials (ex. Precision Engineered Products, 262 Broad Street, North Attleboro, Mass. 02760). An example of such a material is “Polymet 258” which is a metal alloy having a (nominal) composition of 25% wt. Ni, 8.5% wt. Cr and the remaining balance being substantially Fe. Other metal alloys may be used, included for example (and without limitation): (i) 18% wt. Ni, 11.5% wt. Cr with the remaining balance being substantially Fe; (ii) 19.4% wt. Ni, 2.25% wt. Cr, 0.5% wt C, with the remaining balance being substantially Fe; (iii) 22% wt. Ni, 3% wt. Cr, with the remaining balance being substantially Fe; (iv) 70% wt. Cu, 30% wt. Zn; (v) 72% wt. Mn, 18% wt. Cu, 10% wt. Ni; (vi) 5% wt. Sn, 0.3% wt. Zn, with the remaining balance substantially Cu; (vii) Cu; (viii) 1008 AK Steel; (ix) Ni; (x) 36% wt. Ni, with the remaining balance substantially Fe (INVAR); (xi) 40% wt. Ni, with the remaining balance substantially Fe; (xii) 42% wt. Ni, with the remaining balance substantially Fe; (xiii) 45% wt. Ni, with the remaining balance substantially Fe; (xiv) 50% wt. Ni, with the remaining balance substantially Fe; (xv) 38.6536% wt. Ni, with the remaining balance substantially Fe; and (xvi) 17% wt. Cr, with the remaining balance substantially Fe. Such are commercially available as other grades of “POLYMET” materials. The thermally responsive element 30 may be substantially fabricated of such a metal alloy or only a part thereof, e.g., the intermediate bow part 30c thereof, optionally with part of leg 30b. The thermally responsive element 30 may include such a thermally responsive metal in part of its construction but may include further non-thermally responsive materials which may be metals, polymers, or other non-thermally responsive materials. The thermally responsive element 30 may also be of a different configuration than that illustrated in the drawing figures.
It is to be understood that the drawings depict a preferred embodiment the invention but such is not to be considered a limiting disclosure and that various modifications are possible and readily foreseen and also that such fall within the scope of the present invention. Thus the drawing figures are to be understood as non-limiting as to the scope of the present inventive teaching. One such modification is the use of an air actuated piston and cylinder assembly in place of the electrically operable solenoid depicted in the drawing figures as the provision of the thermally responsive element would be equally effective regardless of the actuation means of the door strike of with the thermally responsive element forms a part.
Provision of a door strike assembly as described herein is useful in a method for controlling the undesired spread of a fire or smoke between adjacent spaces separated by the door wherein a fire or smoke condition exists in at least one of these spaces, as it facilitates in a door associated with a door strike of the present invention from being opened when the door and its electrically operable door strike are exposed to a fire. Such a method ensures that occupants present within a building or structure do not open doors within the building in which a fire is present when the door strike and its thermally responsive element are at an elevated temperature. Such may improve the safety of the occupants of the building under such conditions, as denying opening of doors between parts of the building which are relatively safe from those parts of the building in which is fire is present. Such retards the unwanted spread of a fire from the latter to the former parts of the building. Such also retards the unwanted spread of smoke from parts of the building in which fire is present to parts of the building in which smoke and/or fire is not present.
And electrically operable door strike and its thermally responsive element may fabricated to provide a very small electrically operable door strike having a relatively compact size as compared to other electrically operable door strike known to the prior art.
Number | Name | Date | Kind |
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4015869 | Horvath | Apr 1977 | A |
4867496 | Thomas | Sep 1989 | A |
5492208 | Goossens | Feb 1996 | A |
5782509 | Kiuyeda | Jul 1998 | A |
8132833 | Schnekenburger | Mar 2012 | B2 |
8366160 | Orbeta | Feb 2013 | B2 |
8814231 | Gandhi | Aug 2014 | B2 |
Number | Date | Country |
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2538437 | Sep 2006 | CA |
10321802 | Dec 2004 | DE |
102005009995 | Sep 2006 | DE |
102005009995 | Sep 2006 | DE |
2227759 | Nov 1974 | FR |
WO-2004101922 | Nov 2004 | WO |
2019126045 | Jun 2019 | WO |
Entry |
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International Search Report and Written Opinion of the International Searching Authority for corresponding application PCT/US2018/066020 dated Mar. 4, 2019. |
Number | Date | Country | |
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20190226234 A1 | Jul 2019 | US |
Number | Date | Country | |
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62608893 | Dec 2017 | US |