Patent Application
20080073914
The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:
Referring to
A spring 18 is provided to power the pin assembly. The spring is held compressed until the heat of a fire releases it to drive the pin 10 forward. The spring 18 is a coil spring and has an inside diameter sufficiently large to receive the back portion 14 of the pin 10 and sufficiently small that the spring cannot move past the annular step 16. The annular step 16 acts as a seat for one end of the spring.
The outside diameter of the spring 18 and the front portion 12 of the pin are sufficiently small that they will fit within the case 20. When the spring assembly is manufactured, the coil spring 18 is placed over the back portion 14 of the pin and the pin is inserted into the case 20 until the head 22 is in approximate alignment with the front end of the case 20. The back portion 14 of the pin then extends out of the back end of the case 20 through a restrictive opening 24 and through a thermally activated fuse 26.
The back portion 14 of the pin is provided with an annular groove 28, which is located just beyond the back end 30 of the fuse 26 when the spring is compressed. The annular groove 28 receives a retaining clip 32. The spring 18 is compressed between the annular step 16 and the inner side of the case 20 at the restrictive opening 24. The fuse 26 is located on the opposite side of the restrictive opening 24 and is held in compression between the restrictive opening 24 and the retaining clip 32.
The fuse 26 is substantially cylindrical, having a length greater than its width, and is made of a plastic. The plastic can be of any type that deforms and/or melts with temperatures above the maximum temperature expected in normal conditions but below the temperatures reached during a fire and below the temperature required to substantially distort the associated fire door.
The desired activation temperature of the fuse 26 may be adjusted by a selection of the desired plastic material and the associated melting and deforming properties of the selected plastic material. In the preferred embodiment however, the fuse 26 is provided with one or more holes 34 that extend perpendicular to the cylindrical axis of the fuse. The holes 34 produce a series of adjacent separating walls 36 which form a web around the fuse.
The web defined by the holes 34 in the cylindrical fuse is sufficiently strong at normal operating temperatures to prevent the pin from moving forward under the biasing force of spring 18. However, when exposed to the elevated temperature of a fire, the web and fuse collapse allowing the spring to drive the pin 10 a sufficient distance out of the case 20 to engage an associated door frame, the floor or an adjacent door. The web defined by the holes in the fuse provides a controlled collapse of the fuse at a desired rate and amount of collapse corresponding to the temperature reached by the fuse during a fire.
The pin assembly is suitable for installation wherever it is desired to latch to adjacent objects in a fire. Typical installations include at the bottom edge of a fire door such that the pin 22 extends downward when released and into engagement with an opening in the floor. This installation is particularly suitable for side-by-side doors and/or for vertical rod door latching systems where the lower rod has been omitted to avoid any risk of injury to a flooring material. The pin assembly may also be used to latch to adjacent doors and/or to connect a door to its doorframe to control warping.
The case 20 is provided with a flange 38 at the front end thereof. The pin assembly is typically installed by inserting the case into a hole drilled in the fire door or in some other object. The diameter of the installation hole is just slightly larger than the diameter of the case 20. The flange 38 has a larger diameter than the installation hole and ensures that the head 22 of the case lies approximately flush with the edge or other surface of the fire door into which the installation hole was drilled.
The case 20 is provided with multiple clip members 40 located at the front end thereof, which act to hold the pin assembly in the installation hole. The case is preferably formed of thin sheet steel produced by stamping and rolling. The clip members provide a resilient spring action by pivoting at the back end 42 where they are connected to the case so that the front end 44 is compressed inward as the pin assembly is inserted into the installation hole. As the assembly fully enters the installation hole, the clip members 40 provide an outward spring pressure that pushes their front ends 44 into engagement with the interior of the installation hole in the door.
Referring to the fuse in
The length of the pin and/or the properties of the fuse material along with the number and location of the holes 34 can be adjusted to provide a pin, which operates at the desired temperature and extends the desired distance outward from the front of the case. Variations in the length of the pin, the length of the fuse and the size of the case and spring may be made to make the pin assembly suitable for different applications.
By positioning the fuse outside the case, it is better exposed to the increased temperature of the fire, which provides more consistent and reliable operation. By adjusting the holes 34 defining the web portion of the fuse, the rate of collapse and the distance the pin extends as a function of the temperature may be adjusted for particular applications.
While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention.
