US3271547A - Fire detector device - Google Patents

Description

Sept. 6, 1966 P. 1.. SEELEY FIRE DETECTOR DEVICE 5 Sheets-Sheet 1 Filed June 14, 1965 INVENTOR PETER L4 SEELEY Attorney Sept. 6, 1966 P. L. SEELEY 3,271,547

FIRE DETECTOR DEVICE Filed June 14, 1965 5 Sheets-Sheet 2 INVENTOR. PETER L. SEELEY Attorney p 1966 P. L. SEELEY 3,271,547

FIRE DETECTOR DEVICE Filed June 14, 1965 5 Sheets-Sheet 5 IN VEN'IOR. PETER L. SEELEY Attorney United States Patent 3,271,547 7 FIRE DETECTOR DEVICE Peter L. Seeley, Don Mills, Ontario, Canada, assignor to Fire Devices Manufacturing Limited, Willowdale, Ontario, Canada Filed June 14, 1965, Ser. No. 469,036 12 Claims. (Cl. 200-142) This application is a continuation-in-part of my copending application, Serial No. 363,508 filed April 29, 1964, now abandoned.

This invention relates to improvements in fire detector devices of the type containing fusible metal which melts when the rise in temperature occasioned by the fire reaches the melting point of the metal, which then actuates an alarm positioned in an electrical circuit.

Fire detector devices are designed to function on the occurrence of one of two conditions. The first condition arises when the rate of rise of temperature of the surrounding atmosphere exceeds a certain figure at which the danger of spontaneous combustion arises; the usual construction designed to function under this condition is an enclosure sealed at one face with a diaphragm which is positioned adjacent to a switch of the electrical circuit containing the alarm signal. The base has calibrated orifice to allow the escape of air on rise in temperature, but the orifice is dimensioned or calibrated so that the air does not escape fast enough if the rate of rise of temperature exceeds a certain figure, at which point the pressure in the vessel is sufiicient to move the diaphragm against the switch, thereby closing the circuit to actuate the alarm.

The other condition under which fire detector devices are designed to function is, of course, the one where the temperature of the surrounding atmosphere has risen to a certain critical level and this is usually effected by attaching to the inner face of the enclosure a mass of fusible metal which holds in tension a spring member. When the temperature reaches the level at which the fusible metal melts the spring is released to strike the diaphragm thereby closing the switch.

While it is economically and desirably practical to combine both functions in the one enclosure, the rapidity of response to the condition where the surrounding temperature has reached the level corresponding to the melting point of the fusible metal is adversely affected because the mass of fusible metal in the enclosure covers a relatively small area to which the heat should be directed while the heat collector, i.e. the enclosure, covers a relatively large one which tends to diffuse the heat.

It is an object of the invention to provide a fire detector device which responds without delay to the condition where the surrounding temperature has reached the melting point of the fusible metal.

It is a further object of the invention to provide a fire detector device which responds without delay when the temperature attains a certain predetermined level and also when the rate of rise of temperature exceeds a certain level.

It is a further object of the invention to provide a rapidly responsive fire detector device which can be mounted at any place for detecting fires.

The present invention aims to overcome this problem of delayed response by having the mass of fusible metal exposed at the outer surface of the enclosure and holding the detent member in inoperative position with the fusible metal in heat conducting relationship with an independent heat collector insulated from the enclosure.

It is a further feature of the invention that a relatively small mass of fusible metal is used to hold the detent member.

Further objects and features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is an exploded view in perspective showing the various parts of one embodiment of a fire detector device constructed according to the invention;

FIGURE 2 is a view part in cross section of an assembled embodiment of a fire detector device constructed according to the invention;

FIGURE 3 is a partial cross section of another embodiment of a fire detector device constructed according to the invention;

FIGURE 4 is an enlarged View, partly in cross section, of a modified plunger used in another embodiment of the invention;

FIGURE 5 is a view, partly in cross section, of the assembly in a fire detector device of the plunger shown in FIGURE 4.

The device, generally denoted by the numeral 10, comprises a cup shaped shell 11 suitably designed to appeal to the eye and preferably constructed of thin gauge material, e.g. aluminum or copper, which has a high heat conductivity to expedite the function of the device when the rate of rise of temperature exceeds a certain value. The device 10 is supported by arranging the diameter of the shell 11 at its base so that it provides a push fit onto a circular abutment 12 of a head member 13, constructed of plastic material, which is secured in the space to be protected by suitable means, e.g. screws. A diaphragm 15 is carried in the circular abutment 12 and a switch 16 is mounted in the head member 13 at a predetermined distance from the diaphragm 15. The shell 11, the head member 13 and the diaphragm 15 form an air chamber 27 and suitably dimensioned apertures 28 are located in the head member 13 to provide for the expansion of air so that the fire detector device can operate on the rate of rise principle.

The shell 11 has a suitably dimensioned centrally positioned aperture in which is disposed a plug of fusible metal 17; by way of example and not by way of limitation the amount of fusible metal is about milligrams and it is selected from the group of fusible metals which melt at around F. In the embodiment of the invention shown in FIGURE 1 a heat collector plate 18 is disposed exterior of the aperture of the shell 11 and the heat collector plate 18 is turned out of a tubular member 19 which is also disposed in the aperture of the shell 11 and is closed by the plug of fusible metal 17. The heat collector plate 18 and the integral tubular member 19 is made of material such as aluminum or copper having a high conductivity and in the preferred embodiment the thickness of the heat collector plate 18 and the wall thickness of the tubular member 19 is about To ensure the most efficient transfer of heat from the heat collector plate 18 to the fusible metal 17 a resilient washer 21 is inserted between the heat collector plate 18 and the shell 11, in this way no heat is dissipated from the heat collector plate 18 to the shell 11. To secure the tubular member 19 in place in the aperture of the shell lll, the upper ends are turned outwards and then downwards to form a flange 30 which bites into a washer 20 bearing against the inner surface of the shell 1*1.

Embedded in the fusible metal plug 17 is the head of a vertically disposed detent member or pin 22 composed of material which melts at a higher temperature, e.g. brass. A plunger 23 composed of a non-conductor, such as plastic, e.g. nylon, surrounds the detent member or pin 22, to which it is secured. A shoulder 24 is provided adjacent to the upper end of the plunger 23 to provide a means for locating one end of a spring 25, the other end of which presses against the inner surface of the shell ill. The spring 25 is in compression to urge the plunger 23 against the diaphragm.

In the embodiment shown in FIGURE 3 an additional heat collector plate 18a is turned out from the tubular member 19, the additional heat collector plate 18a being spaced from the heat collector plate 18 insulated from the shell 11.

The operation of the device will be apparent in that the detent member or pin 22 will be released when the plug of fusible metal 17 melts and the spring 25 will force the plunger 23 against the diaphragm 15 to operate the switch 16.

In the embodiment shown in FIGURE the plunger 23, composed-of plastic, preferably a phenolic resin, has a stem 26 which is smaller in diameter than the integral tubular member 19 of the heat collector plate 18 The free end 27 of the stem 26 is slightly enlarged, as illustrated more particularly in FIGURE 4, preferably terminating in an abutment 28 which fits into a corresponding recess provided in the collector plate 18. The enlarged end 27 of the stem 26 together with the abutment 28 is provided with a coating 29 of a plating metal such as copper, preferably deposited thereon in a conventional manner by immersion in an electro chemical bath, which coating extends the whole extent of the enlarged end 27 in the form of a cap to terminate at least at the commencement of the stem 26.

The copper coating 29 provides the base for securing the enlarged end 27 to the metallic heat collector plate 18 with a thin film of fusible metal '17, which by way of 7 example and not by way of limitation, may be as low in quantity as 15 milligrams fusing the copper coating 29 to the heat collector plate 18. The enlarged end 27 serves as a replacement for the pin 2-2 as a detent member. This reduced quantity of fusible metal 17 provided by a film as compared with a plug, further improves the sensitivity of the device when the surroundings reach the critical temperature. As already mentioned the arrangement has the advantage of dispensing with the pin 22 and, furthermore, even if the enlarged end 27 of the plunger 23 becomes detached from the surrounding deposited copped coating 29 the fact that the latter extends at least to the start of the stem 26 in the form of a cap ensures that the plunger 23 will still remain in position.

While certain embodiments have been illustrated and described for the purpose of disclosure, it will be understood that the invention is not limited thereto, but contemplates such modifications and other embodiments as may be utilized without departing from the invention.

I claim:

1. A fire detector device comprising a head, circuit closing means thereon, a flexible diaphragm supported by said head movable towards said circuit closing means, a shell having an opening and held onto said head, a thin wall tubular member disposed in said opening and turned out at its lower end for a predetermined distance to define a heat collector plate, means securing said tubular member within said opening, means insulating said heat collector plate from the exterior of said shell, a releasable detent member mounted in said shell and adapted on release to move said diaphragm towards said circuit closing means and fusible means in heat conducting relationship sealing said tubular member and holding said detent in inoperative position.

2. A fire detector device comprising a head, circuit closing means thereon, a flexible diaphragm supported by said head and movable towardssaid circuit closing means, a thin wall shell having an opening and held onto said head, a thin wall tubular member disposed in said opening and turned out at its lower end for a predetermined distance to define a first and second heat collector plate in spaced relationship with respect to each other, means securing said tubular member within said opening, means insulating said first heat collector plate from the exterior of said shell, a releasable detent member mounted in said shell and adapted on release to move said diaphragm towards said circuit closing means and fusible means in heat conducting relationship sealing said tubular member and holding said detent member in inoperative position.

3. A fire detector device comprising a head, circuit closing means thereon, a flexible diaphragm supported by said head and movable towards said circuit closing means, a thin Wall shell having an opening and held onto said head, a thin wall tubular member disposed in said opening and turned out at its lower end for a predetermined distance to define a first and second heat collector plate in spaced relationship with respect to each other, means securing said tubular member within said opening, means insulating said first heat collector plate from the exterior of said shell, a releasable detent member mounted in said shell with one end located in said tubular member adjacent said second heat collector plate, said detent member being adapted on release to move said diaphragm towards said circuit closing means and fusible means sealing said tubular member and holding said detent member in inoperative position.

4. A fire detector device according to claim 1, wherein the means for securing said tubular member comprises a flange turned out at its upper end in spaced relationship with the interior of said shell and spacing means in contact with said shell and bearing onto said flange.

5. A fire detector device according to claim 2 wherein the thickness of said first and second heat collector plates is about %000".

6. A fire detector device according to claim 1 wherein the mass of said fusible means is approximately milligrams. Y

7. A fire "detector device according to claim 2 wherein the end of said detent in said member is a pin constructed of a metal having a melting point higher than said fusible means and the other end of said pin is secured to one end of a nylon member, the other end of said nylon member having an abutment and a spring bearing onto said abutment and compressively engaged with said means securing said tubular member.

8. A fire detector device comprising a head, circuit closing means thereon, a flexible diaphragm supported by said head movable towards said circuit closing means, a shell having an opening held onto said head, said diaphragm, said shell and said head defining an air chamber provided with a suitably dimensioned aperture regulating the release of heated air at a predetermined rate from said chamber to maintain the level of pressure, said diaphragm being responsive to increase of pressure of heated air in the chamber to flex towards said circuit closing means, a thin wall tubular member disposed in said opening and turned out at its lower end for a predetermined distance to define a heat collector plate, means securing said tubular member within said opening means insulating said heat collector plate from the exterior of said shell, said insulating means sealing the space defined between said tubular member and the perimeter of said opening, a releasable detent member mounted in said shell and adapted on release to move said diaphragm towards said circuit closing means and fusible means in heat conducting relationship sealing said tubular member and holding said detent member in inoperative position.

9. A fire detector device comprising a head, circuit closing means thereon, a flexible diaphragm supported by said head movable towards said circuit closing means, a shell having an opening and held onto said head, a thin wall tubular member disposed in said opening and turned out at its lower end for a predetermined distance to define a heat collector plate, means securing said tubular member within said opening, means insulating said heat collector plate from the exterior of said shell, a plastic releasable detent member mounted in said shell with one end located in said tubular member adjacent said second heat collector plate and adapted on release to move said diaphragm towards said circuit closing means and fusible means in heat conducting relationship sealing said tubular member and holding the said end of said plastic detent member in inoperative position, said end of said plastic detent member being covered with a thin layer of a coating metal to which is attached said fusible means.

10. A fire detector device according to claim 9 in which the end of said plastic member is made of phenolic resin.

11. A fire detector device according to claim 9 in which the end of said detent member is enlarged and said coating extends over said enlargement at least to the body of said detent member.

12. A fire detector device according to claim 9 in which said coating of metal is copper.

References Cited by the Examiner BERNARD A. GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.

Claims (1)

1. A FIRE DETECTOR DEVICE COMPRISING A HEAD, CIRCUIT CLOSING MEANS THEREON, A FLEXIBLE DIAPHRAGM SUPPORTED BY SAID HEAD MOVABLE TOWARDS SAID CIRCUIT CLOSING MEANS, A SHELL HAVING AN OPENING AND HELD ONTO SAID HEAD, A THIN WALL TUBULAR MEMBER DISPOSED IN SAID OPENING AND TURNED OUT AT ITS LOWER END FOR A PREDETERMINED DISTANCE TO DEFINE A HEAT COLLECTOR PLATE, MEANS SECURING SAID TUBULAR MEMBER WITHIN SAID OPENING, MEANS INSULATING SAID HEAT COLLECTOR PLATE FROM THE EXTERIOR OF SAID SHELL, A RELEASABLE DETENT MEMBER MOUNTED IN SAID SHELL AND ADAPTED ON RELEASE TO MOVE SAID DIAPHRAGM TOWARDS SAID CIRCUIT CLOSING MEANS AND FUSIBLE MEANS IN HEAT CONDUCTING RELATIONSHIP SEALING SAID TUBULAR MEMBER AND HOLDING SAID DETENT IN INOPERATIVE POSITION.

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