US 3725972 A
A releasable link is provided to open under predetermined conditions; said link having the capacity to be reset under predetermined temperature conditions. The link includes a bimetallic element for effecting opening and closing. The link may also include heating means for actuating the bimetallic element, and secondary circuit control means for actuating signals or controlling current to the heating means.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 McCabe [451 Apr. 10, 1973  FIRE LINK AND METHOD OF 1,471,537 10 1923 Wills et a1 24 230 F UX ACTUATING SAME 2,253,861 8 1941 McKune et a1. ..16/48.5
, 2,573,160 10/1951 Norman ..49 1
 Inventor: Francis J. McCabe, Hollow Horn 3,273,632 9/1966 Mccabe u 160/1 Road & Cafferty Hill Road, Erwin- 3,584,763 6/1971 Donselman ...49/1
na, Pa. 18902 587,823 8/1897 Holbrook et al. ...49/1
. 599,800 3 1898 Scribner 4 ..49 2
 Wed Sept 1971 3,249,148 5/1966 Zablodil et a1. ..160/5 x 2 N 178 111 3,415,562 12/1968 Petersen 1 ..l6/48.5 X 3,648,326 3/1972 Gaysowski ..l6/48.5
Related US. Application Data Continuation-impart of Ser. No, 103,467, Jan. 4, 1971, abandoned, and a continuation-in-part of Ser. No. 133,196, April 12, 1971, abandoned.
US. Cl ..16/48.5, 49/2 Int. Cl. ..E05f 15/20 Field of Search ..l60/l, 2, 6, 8, 5;
References Cited UNITED STATES PATENTS Simpson ..24/230 F UX I Shuman 160/1 Primary Examiner-Donald A. Griffin Attorney-frank J. Benasutti  ABSTRACT A releasable link is provided to open under predetermined conditions; said'link having the capacity to be reset under predetermined temperature conditions. The link includes a bimetallic element for effecting opening and closing. The link may also include heating means for actuating the bimetallic element, and
secondary circuit control means for actuating signals or controlling current to the heating means.
18 Claims, 5 Drawing Figures PATENTEBAPR 1 D I913 SHEET 1 [IF 3 'PATENIEDAPM oma 3725972 'SHEET 3 or 3 24 ZIO 284 280 2 1 FIRE LINK AND METHOD OF ACTUATING SAME CROSS-REFERENCE TO RELATED APPLICATIONS 133,196, filed Apr. 12, 1971, and discloses and claims,
in part, the subject matter disclosed and claimed in those applications.
BACKGROUND OF THE INVENTION This invention related to links for use in automatically actuated equipment forming a part of a tirefighting system, and more particularly, to a fire link for use with devices such as fire dampers in air ducts.
In the prior art, such links were generally made of two pieces of metal fused together with solder; the solder being the means for releasing the link when the ambient temperature rose above a certain level; for example, 160 F. Such links are shown in use with fire dampers in my prior U.S. Pat. Nos. 3,273,632 and 3,401,734. It will be observed in these patents that the melting or change of state of the solder permits the link to be opened by the fire damper to close off the air duct.
It is also known to provide a means for melting the solder by remote control.
In practice it is difficult to make these links accurately, since it is particularly difficult to control the amount of solder and the solder distribution on the links. Further, as a practical matter the links are not 'resettable.
It is desirable to provide a link which is capable of being manufactured so that it opens or releases at a predetermined temperature. It is further desirable to have such a link which can be reset and which can be remotely operated.
SUMMARY OF THE INVENTION My invention provides a mechanically operable resettable link capable of highly accurate predetermined control as to opening and closing; which does not undergo a change of state in order to function. The link also provides a means whereby remote control can be used to actuate the link. The link comprises two parts interconnected by a pin. When the pin is withdrawn, the parts can be separated. A means is provided for withdrawing the pin; said means being a bimetallic element upon which the pin is mounted.
Further means are provided in alternate embodiments of the invention for heating the bimetallic element by remote means and for automatically signalling and controlling the heat to the element.
Accordingly, it is an object of my invention to provide a new and novel fire link which can be simply and accurately manufactured.
Another object of my invention is to provide such a link which does not undergo a change of state and which can be reset.
A further object is to provide such a link which can be remotely controlled.
A further object is to provide a link with means to control secondary circuitry for signalling or controlling the action of the link.
These and other objects of my invention will become apparent from the following description with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a tire link in accordance with one embodiment of the present invention;
FIG. 2 is a top view of the link shown in FIG. 1;
FIG. 3 is a view taken as indicated by the lines and arrows e-3 in FIG. 2;
FIG. 4 is a view of another embodiment of my invention, similar to FIG. 3; and
FIG. 5 is a view of another embodiment of my invention, similar to FIG. 3 with the parts reoriented.
The figures include positive and negative signs to indicate electrical potential.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Although specific forms of the invention have been selected for illustration in the drawings, and the following description is drawn in specific terms for the purpose of describing-these forms of the invention, this description is not intended to limit the scope of the invention which is defined in the appended claims.
- In FIG. 1 a link is shown in accordance with one em bodiment of the present invention wherein a remote control device is utilized with the link to accuate the link and openit. This remote control device comprises an electrically operated heating element. To understand the nature of this heating element and its function with the basic link construction in accordance with the preferred embodiment of the present invention, I will first describe the link and its function without the use of this electrical heating element.
The basic link comprises two elements which are pin connected together. The first link element 10 is a substantially flat, rectangular metal strip having joined thereto in any suitable manner a number of other metal strips and including at one end a hole 12 providing a ready means for attachment to a wire or chain in a tire damper or the like.
The second link element 14 is also a substantially rectangular flat metal strip with a hole 16 at one end also providing a means for ready attachment to a wire or chain in a fire damper or the like. The elements are normally held together by pin 18 which passes through a clearance hole 20 in element 10 and a clearance hole 22 in element 14.
A flange 24 is provided on the element 10. The flange is made of a flat strip of metal which has been bent intermediate the ends thereof so that when one portion is held flat against the underside of element 10 and is welded thereto, the remainder extends outwardly away from and then parallel to the element 10. Thus, there is formed an envelope or enclosure confining the element 14; both while the pin 18 is in the position shown in FIG. 3, and while it is being withdrawn.
The pin 18 passes through the clearance hole 26 in element 24. The pin is connected by means of a swaged rivet 28 to'a bimetallic element 30. The bimetallic element is made of two flat strips of dissimilar metals adhered together in any well known manner. Bimetallic elements are commonly used in thermostats and the like. The strips of metal forming the bimetallic element 30 are attached at one end to the element as by means of the rivets 32. The bimetallic element is similar in form to the element 24 so that it extends outwardly from the point of engagement at 32 to a point clearing the element 24, at which point it extends parallel to the element 10.
What has been described thus far is the basic link in accordance with this invention, although it will be apparent from this disclosure that changes could be made within the principle of the invention. In operation the bimetallic element is arranged so that in normal ambient temperatures it is in the position shown in FIG. 3 with respect to the element 10 and the element 14. In this position the link is connected or closed, and if the ends of the members 10 and 14 were connected to a wire or a chain in a fire damper the forces on the link would be in the direction of the arrows shown in FIG. 3.
The link would be in position to retain the blades of the the metals in the bimetallic element would cause its free end 34 to move away from the free end 36 of the element 10. As it did so, it would withdraw the pin 18 from the hole 20 and hole 22 and as the pin was completely withdrawn from the hole 22 the elements 10 and 14 would separate from one another under the action of the forces from, say, the weight of the damper blades.
Note that the action of the link is purely mechanical and it does not undergo any change of state. Therefore, in the event that the link is not damaged in whatever fire caused the temperature to rise, the link can be reset at normal temperatures. The bimetallic element returns to the position shown in FIG. 3 at normal temperatures.
The large oval hole 38 in the element 10 provides a means for allowing the heated air to flow through and come into contact with bimetallic element 30, thereby increasing the efficiency of the device.
In an alternate embodiment of this invention, a means is provided for remotely controlling the action of the bimetallic element. This means comprises an electrical heating element which, in its preferred embodiment, comprises nichrome wire 40, which is adhered by any suitable means, such as adhesive to the inner surface of the bimetallic element 30. The positive and negative electrical leads indicated on the drawings provide a means to establish current flow through the nichrome wire from any suitable controlled electrical source (not shown) to heat the wire and the bimetallic element. Thus, it is possible to energize the nichrome wire and provide heat to the link to open it in the manner previously described and allow the tire damper, or whatever device was being controlled by the link, to become operative. It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described and illustrated in order to explain the nature of this invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the claims. For example, a portion of the bimetallic element itself can be the heating means.
In the embodiment shown in FIG. 4, the electrical leads are directly connected to the bimetallic element 130. Since the element will carry current, it is insulated at its point of connection to element 110 as well as at the pin 118. This electrical insulation is provided by washers 150, 151, 152 and 153, and by bushings 154 and 155. In this manner, the bimetallic element 130 can be heated directly from a remote source to open the link.
Alternatively, in either of the electrically operated embodiments, the metals in the bimetallic element can be reversed so that it must be constantly heated in order to remain closed. If the circuit is opened and the electrical power cut off, then the link would open automatically.
Mechanical details can also be changed within the scope of this invention, such as by providing a hook 112 at the end of the element 110 in lieu of the hole 12 FIG. 1 and/or a double ended hook 116 in lieu of the element 14, FIG. 1.
In FIG. 5 a further embodiment of my invention is shown in an open condition, that is, wherein the bimetallic element has withdrawn the pin from the envelope created by the flange 24 and the main body 210 of one element of the link thereby allowing the other element of the link to be separated by the opposed forces (shown by arrows in FIG. 3). This embodiment is provided with means for controlling a secondary cir-- cuit for purposes of signaling in the event that the link is opened or for purposes of controlling the amount of heat supplied to the bimetallic element in order to prevent it from overheating and being destroyed. This secondary circuit control means comprises two substantially flat narrow gage flexible metallic elements which are normally bent so that they are in contact when the device is in the closed position with the pin 218 fully inserted through the holes in the hole member 210. The elements 280 and 282 each have a small metallic button 284,286 respectively riveted to the adjacent free ends thereof. The other ends are retained as follows. The end of the element 280 is held in electrical contact with the electrical take off lug 288 which is insulated from the main body 210 by the insulator pad 290. On the other side of the element 280 there is a further insulator pad 291 which insulates these elements from the bimetallic element 230. An electrical lug 292 is in electrical contact with the bimetallic element 230 and an insulator pad 293 separates this lug from a metallic retainer pad 294. All of these pads and parts are held together by a plurality of rivets, such as the rivet 295, which pass through clearance holes in the electrical elements and are rolled over to retain the elements in a firm fixed position. The pin 218 is electrically insulated by a washer 219 from element 282 which is in electrical contact with the bimetallic element 230. A further insulator washer 221 is provided between the retainer washer 223 and the rolled head of the pin 218 so that these parts are likewise held in a firm fixed position and are electrically insulated as shown.
When the bimetallic element is heated and is moving from a fully closedposition to the position shown in FIG. 5, the buttons 284, 286 will remain in contact for a predetermined distance. In the event that it is desired to signal the opening of the link, the elements 280, 232
can be bent before hand to an extent necessary such that when the pin moves to the position shown in FIG. 5 the buttons will separate as shown and break a circuit. A circuit, such as a low voltage secondary signal circuit can easily be provided from the lugs 288, 292 and secondary instrumentation or signal controls can be actuated by merely braking this circuit. These are not shown in further detail, since such circuits are well known.
Alternatively, if it is desired to heat the bimetallic element 230 through circuitry connected to these lugs, the separation of the buttons at a predetermined point will prevent overheating by breaking the circuit. However, the link will be maintained in the opened position as long as the circuit remains closed and as the bimetallic element 230 cools the buttons 284, 286 will come together and close the circuit again thereby reheating the link.
It will further be understood that the Abstract of the Disclosure set forth above is intended to provide a non-legal technical statement of the contents of the disclosure in compliance with the Rules of Practice of the U.S. Patent Office, and is not intended to limit the scope of the invention described and claimed herein.
1. A releasable link having only two elements comprising: a first element; and a separate heat activated bimetallic second element not'fixedly connected to, but directly engaged with said first element and coacting therewith to allow said elements to separate in response to temperature change without changing the state of either element.
2. The invention of claim 1 wherein a remotely controlled heating means is connected to said bimetallic element for actuating said bimetallic element.
3. The invention of claim 2 wherein said heating means comprises an electric heating element engaging said bimetallic element.
4. The invention of claim 1 wherein a pin is attached to said bimetallic element and passes through said first element.
5. The invention of claim 4 wherein said bimetallic element is fixedly connected to a base at one end and said pin is connected to the free end thereof.
6. The invention of claim 4 wherein said second element includes a means embracing said first element to confine it. I v
7. The invention of claim 1 wherein said second element is provided with means to provide an air passage to the bimetal.
8. The invention of claim 1 wherein said electrical means are connected to said bimetallic element for heating said element.
9. The invention of claim 8 wherein said electrical means comprises electrical leads directly connected to release of said elements.
12. The invention of claim 11 wherein said electrical means comprises a pair of electrical contacts.
13. The invention of claim 12. wherein one of saidcontacts is connected to and moves with said bimetallic element.
14. In a method of actuating a tire link to release the link elements from their engaged condition, the improvement comprising: electrically heating said link to control the engagement of said link elements without changing the state of the link.
15. In the method of claim 14 applied to a link having a bimetallic element to control the engagement of said link elements, the improvement comprising: remotely supplying electrical current directly to said bimetallic element to heat said element to control said engagement.
16. The invention of claim 15, wherein said current is continuously supplied to said bimetallic element to retain said link elements in their engaged condition.
17. In the method of claim 15 automatically controlling the current supplied in response to the position of the bimetallic element.
18. In the method of claim 14 automatically electrically signalling the release of said elements.