US2367639A - Heat-responsive device - Google Patents

Description

Jan. 16, 1945. R D, CONBOY 2,367,639

HEAT-RESPONSIVE DEVICE Filed March 7, 1940 v man' 55 5o INVENTOR ATTORNEYS Patented Jan. 16, 1945 ascissa HEAT-nnsroNsrvE DEVICE Russell D. Conboy, Waterbury, Conn., assignor to Casco Products Corporation, Bridgeport, Conn., a corporation of Connecticut Application March 7, 1940, Serial No. 322,698

(Cl. Zoll-142) 14 Claims.

This invention relates to heat-responsive devices, and, more particularly, to a, thermoplastic fuse of simple construction and high operating efiiciency.

In thermoplastic fuses of the type of the present invention, a heat-responsive element controls vthe relative mechanical movement of interacting4 parts and generally holds said parts against separation until the ambient temperature reaches one in excess of a predetermined temperature.

In similar devices heretofore proposed, fusible elements have been employed for controlling the mechanical movement of certain interacting parts, but certain of these previously proposed elements have been unsatisfactory for the reason that they generally have been formed of wax or wax-like compositions and their fusing temperatures could not be maintained constant by ordinary production methods, so that while one supply of elements would fuse at the desired heat others would fuse at temperatures below or above the desired one.

A'further difficulty was found' in the use of these prior fusible elements formed of Wax or wax-like compositions, in that the element would often soften and be no longer effective to control the mechanical movement of the interacting parts after the ambient temperature of the element had reached and maintained a temperature substantially that of the fusing temperature of the element, but yet below the desired temperai ture.

To obviate the difficulty presented by the use of these elements formed of wax or wax-like compositions, certain metallic materials, not afy fected by prolonged temperatures substantiallyv ments formed of metallic material, as the material was current-conducting, presented diilicultles v not to be found in the elements formed of wax or wax-like compositions, for where these elements were used to controla circuit, many times,

after the material had fused or melted, wouldsome into contact with members forming a Apart of the circuit controlled and would short circuitI the same.

'I'hese diiliculties found in the previously proposed devices of this type are obviated by the present invention, in that the material of the heat-responsive element herein disclosed is not affected by prolonged temperatures substantially that of its fusing temperature. The element is, therefore, effective to control the mechanical mo'vement of the parts until the desired ambient temperature is reached. The element, furthermore, is comprised of a nonconducting material and the difculty of the fusible material short circuiting, where the element is used to control a circuit, is completely obviated.

The material of which the heat-responsive element is formed furthermore gives off a characteristic odor when it fuses or melts so that a person within the vicinity of the fuse will be apprised that the element has fused or melted, whereupon that party may replace the element with a fresh one.

The heat-responsive element of the present invention is formed of chemically pure sulphur which has a melting point of 238 degrees F. `The melting point of chemically pure sulphur does $0 quite economical.

Other features and advantages will hereinafter appear.

In the accompanying drawing:

Figure 1 is a sectional view illustrating a heatresponsive device controlling the discharge of the water in an automatic sprinkling system.

Fig. 2 is a sectional view illustrating a'heatresponsive device made in accordance with my invention as applied to the control of 'an electric circuit.

Fig. 3 is an exploded perspective view of the metallic cartridge which houses my destructible wafer. t V

Fig. 4 is a perspective view showing the cartridge assembled.

Fig. 5 is a sectional view illustrating a modified form of my invention as applied to the control of an electric circuit.

In the form of the present invention, where the same is employed to control or operate a discharge nozzle of a water or fluid system to prevent the spread or a conilagration, a nozzle I0, referring now to Fig. 1, is provided with a series of outlet ports I I held closed by a. valve I2 engaging a Seat i3 formed interiorly of nozzle ill. Secured to the outer end of the valve I2 is a disk I4 having a central concavity receiving the base of a plug I having a substantially conical nose I6. The plug I5 preferably is provided with a tapped hole receiving a screw I1 by means of which the plug, disk and valve are secured together as a. u

y. prises a dish-like member 23 formed of preferably a conducting material such as brass or the like having a portion of its transverse wall 2i perforated to form a plurality of centrally projecting lingers 24. The cartridge is assembled by depositing in the dish-like member 23 a quantity of powdered, chemically pure sulphur and then a second dish-like member also formed of some conducting material is disposed in the first member 23 with its open end disposed downwardly whereupon the two dish-shaped members are urged together and the sulphur is compressed to form a thin wafer-like mass held by members 23 and 25. The annular wall of the dish-shaped member 23 is then peened over to form a flange for holding the members 23 and 25 together and to form a casing housing the sulphur wafer.

I prefer to use chemically pure sulphur as my fusible material, for chemically pure sulphur is economically obtained on the open market and has a constant melting or fusing temperature. Chemically pure sulphur, furthermore, as it melts or fuses at a definite critical temperature is not affected by prolonged temperatures substantially that of its melting or fusing temperature, so that there is no danger of my cartridge breaking down should it reach and maintain a temperature almost that of 238 degrees F., the melting point of chemically pure sulphur. l

It will be seen that when the ambient temperature of the device, illustrated in Fig. 1, reaches the melting point of the sulphur, the sulphur will melt and the pressure at the noz- 4zie `Il will urge the valve I2 outwardly of its seat causing the conical nose I6 of the plug I5 to bend the fingers 24 of the casing inwardly and penetrate or pierce the wafer. The fluid under pressure will then be forced through the various outlet ports II thoroughly sprinkling any article within the radius of the spray.

To render the wafer quickly responsible to the ambient temperature of the device, the cap I8 is provided with a plurality of slots 26 so that the wafer is not insulated from the surrounding atmosphere by the cap I9 nor is it dependent upon the conductivity of the cap I8 to transfer the heat of the ambient atmosphere to the cartridge. The cap I9 as it is threaded onto the nozzle Il) permits the fused cartridge to be quickly replaced by a fresh one by merely unscrewing the capfrom the nozzle, removing the old cartridge and prop` erly replacing it with a new one.

My device, as will be readily understood now, is particularly adapted for controlling an electrical circuit for the heat-responsive material, that is, the sulphur which is used to form the heat-responsive element is non-conductive, and, consequently, all danger of the material short circuiting the device, after the same has fused or melted, is obviated.

'I'here is shown in Fig. 2 a form of my invention, where used to control an electric circuit,

particularly a thermal actuable device responsive to heat created by a surge of current, that is, an overload of the circuit controlled. In this form of the invention, a shell 21 houses a block 28 cf insulating material forming a transverse wall therefor which carries a pair of contacts 29 and 30. One end of each contact is anchored to the outer face of the block 28 by suitable terminal connections 3l and 32 having their outer ends threaded to take suitable fastening devices for securing conductors thereto. The inner face of the block 29 is provided with a hollow boss 33 receiving a spring 34 acting against a stud 35 provided with a collar 36 engaging the one face of a circular disk 31 of insulated material. The stud 35 terminates in a threaded reduced position extending through a centrally located aperture in the disk 31, and threadedly received in a socket formed in the base of a conical shaped plug 38. lThe annular wall of the disk 31 is provided with a camming surface 39 adapted to engage and cooperate with a reverse bent portion formed adjacent the extremity of each contact 29 and 3l). A pair of cooperating contact clips 4I) and 4I are received within suitable grooves formed in a sleeve 42 of insulating material fitted within the shell 21. The contact clips 40 and 4I are substantially U-shaped and the bow of each receives my novel heat-responsive cartridge described in detail during the description of the form of the invention illustrated in Fig. 1. A disk 43 of insulating material closes the end of the shell 21 and is held in position by a removable cap 44 threadedly mounted to the one end of the shell 21. The opposite end of the shell 21 is peened over to form an annular flange 45, and it will be seen that when the cap 44 is threaded onto the shell 26, the same will clamp the block against the flange with the contacts 29 and 3D engaging contact fingers 46 and 41 of the clips 40 and 4I respectively and hold the perforated wall of the cartridge in engagement with the nose of the plug 38. The device can be quickly connected into a circuit by merely securing conductors t0 the terminals 3I and 32. The circuit through the device includes terminal 3|, contact 29, contact finger 46, clip 40, the brass or other conducting housing of the cartridge, clip 4I, contact finger 41, contact 30 and terminal 32.

Under normal circuit conditions, contacts 29 and 30 engage the contact fingers 46 and 41 respectively, but should a surge of current occur or should the circuit be overloaded, the sulphur wafer will become heated due to the heat caused bythe resistance of the brass of the housing therefor and the same will fuse or melt upon the housing reaching the melting temperature of sulphur. The plug 38, upon the melting or fusing of the wafer urging the fingers 24 inwardly of the cartridge to partially pierce the same whereupon the annular camming surface 39, as

. the disk31 is moved toward the left, as viewed in Fig. 2, will engage the reverse bent portions of the contacts 29 and 30. The camming surface, as the disk is further moved under the action of the spring, will cooperate with the reverse bent portion of the contacts 29 and 30 and cam the contacts apart t0 break the circuit at the points of engagement between the contacts 29 and 46 as well as contacts 41 and 30. The blow.. ing of the fuse will not only be indicated by the breaking of the circuit controlled, but also by the characteristic odor which sulphur gives of! when it is melted. The destroyed cartridge may be easily replaced with a fresh one by merely unscrewing the cap 44 from the shell 21, slipping the disk 43 from its position within the shell 21 which exposes or renders accessible the cartridge and the contact clips 40 and4l so that the old cartridge and contacts may be, removed. A fresh cartridge may then .be easily assembled with the contact clips which may be slid back into their proper positions, the disk 43 replaced, and the cap 44 screwed back onto the shell 21.

It is many times desired to use a heat-responsive device which will not only be responsive to an overload of the circuit controlled but be also responsive to the heat generated by some heating element, should the circuit to the heating element be maintained'for an unduly prolonged period.

I have shown in Fig. the application of my invention to such avdevice. In this form of the invention, a casing comprising a metallic shell part 50 has a transverse wall formed by a disk 5l of insulating material which carries a stud .52 having its inner end peened over to form a contact 53, and provided with a collar 54 engaging the outer face of the disk 5|. In this form of the invention, a substantially conical shaped,rv

plug 55 is centrally carried by a disk 56 havingfjits peripheral edge bent over toform an annular,

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of engagement with the contact 53, thereby breaking the circuit. It will also be seen that the device will also be effective to break the circuit due to an overload of the current, for the brass or other conducting housing of vthe cartridge again formsa part of the circuit. If the cartridge should become overheated sufficiently to cause the sulphur wafer to melt or fuse, the circuit will be broken, as just above explained in connection with the description of the device shown in Fig. 2,

A fused cartridge, in this form of my invention, is as easily replaceable with a new one as in the two previously explained .forms of my invention. In this form of the invention, a fused cartridge may be removed from the device by merely unscrewing the flanged ring 6|, which is preferably carried by the disk 60, so that; the disk and ring may be removed as one element and the fused cartridge substituted for a fresh one. v

Variations and modifications may be made within-the scope of this invention and portions of the improvements may be used without others.

I` claim:

1. In a thermal-responsive device of the type described,I means for controlling the mechanical displacement of elements forming a part of said f thermal device, said means comprising abody of vsulphur fusible` at a predetermined temperature.

' 2. In" a thermal-responsive device of the type contact 53 of the stud 52.

The open end of the shell 15l! is closed by a transverse wall formed byv I a disk 60 of insulating material heldin place by a flanged ring 6l threaded onto the shell 50. The disk 60 carries a centrally located stud 62 Whose one end is peened over to form a contact 63 projecting beyond the interior face of the disk 60. A collar 64 carried by the stud 62 engages the exteriorface of the disk BU, and cooperates with the contact to hold the stud against movement. Interposed between `the'head of the contact 63 0f the stud 62 and the conical shaped plug. 55 is one of my novel cartridges heretofore described with the plug engaging the perforated wall thereof. The device shown in Fig. 5 is intended to be electrically and mechanically connected in heatreceiving relation with a heating element, not shown, such as is employed in any electrically heated appliance or device by means of the stud 52. The stud 62 forms a means for securing the device to the other side of the circuit so that the device forms a part of the heating element circuit. It will be seen that With the stud 52, electrically and mechanically connected to the heating element of the appliance to which the device is attached and with the stud 62 connected with the other side of the circuit, the circuit through the device will include the stud 52, contact 53, plugv 55, the brass or other conducting f housing of the cartridge, contact 63 and stud 62. If the heating element in the circuit to which the device is connected is allowed to remain in circuit for lan undue length of time, heat will be readily conducted by the metallic stud -52 to the metallic plug 55 which, when becoming sufficiently heated, will cause the sulphur wafer of the cartridge to melt or f .use and allow described, means for controlling the mechanical displacement of elements forming a part of said thermaldevice, said means comprising a waferlike'massfiof sulphur housed Within a casing of current-conducting material.

3. In a thermal-responsive device of the type described, means for controlling the mechanical displacement of elements forming a part of said thermal device, said means comprising a waferlike mass of chemically pure sulphur housed within a casing of heat-conducting material.

4. In a device of the type described, the combination with a casing, of an element movable in said casing; an element xed relative to said movable element; means normally tending to displace said elements; and means in said casing, accessible for replacement through a removable closure forming' a part of said casing, for preventing said displacement, said means comprising a wafer of sulphur, fusible at a predetermined temperature, the fusing of said wafer permitting said means to displace said elements.

5. In a device of the type described, incombination with a casing, a. movable contact carried within said casing; a fixed contact carried within said casing and normally engaging the movable contact; means tending to separate said contacts; and a fusible member preventing the separation of said contacts, said fusible member comprising a lwafer of sulphur destructible at a. predetermined temperature, the destruction of said wafer permitting the means to separate said contacts.

6. In a device of the type described comprising a housing; a pair of relatively movable contacts carried by said housing; means normally tending to separate said contacts; and means associated with one of said contacts for holding the Icontacts in electrical engagement until said means attains a temperature higher than one predetermined, said means comprising a wafer of sulphur fusible at a predetermined temperature.

'7. In a device of the type described comprising a housing; a pair of switches, each comprising a pair of relatively movable contacts; conductor means connecting said switches in series resilient means normally tending to separate the contacts oi said switches; and means acting against said resilient means to hold said contacts in good electrical engagement, said means allowing the resilient means to open saidswitches by separating said contacts upon the means attaining a temperature higher than one predetermined, said means including a body I chemically pure sulphur fusible at a predetermined temperature to permit both switches to be simultaneously opened; said conductor means between the two switches lying in close proximity to said body of sulphur whereby the latter is responsive to the heat generated by the current carried by the switches.

8. In a device oi' the type described comprising a pair of relatively movable contacts; means tending to separate said contacts; and a fusible retaining member for holding said contacts in electrical engagement against the action of said last-named means, said fusible member comprising a wafer-like mass of sulphur housed within a casing of current-conducting material forming a conducting link in the circuit through said device, the sulphur being fusible upon the casing attaining a temperature equal to the melting point oi sulphur topermit the resilient means to separate said contacts, said device being responsive at least in part to the heat generated by the current traversing said casing.

9. In a fusible cutout for an electrically heated device, a pair of relatively movable contacts; means tending to separate said contacts; a fusible retaining member engaging one of said contacts for holding said contacts in electrical engagement; a mounting means for said device providing a direct heat path between the heating element and the contact engaged by said fusible retaining member; and means for insuring the operation of said fusible retaining member at substantially the same temperature irrespective of the temperature of the heating element by reasonof changes of voltage of the supply circuit, said means comprising a current-conducting casing housing said fusible retaining member and forming a part of the circuit through said cutout, said fusible retaining member comprising a wafer-like mass oi' sulphur.

10. In a fusible cutout for an electrically heated device, a supporting means for thermally and electrically connecting a fusible member to the heating element of said device, said fusible member comprising a wafer-like mass of sulphur housed within a casing of current-conducting material which forms a conducting link traversed by a current corresponding in magnitude to the current traversing said heating element.

11. In a device of the ty-pe described, a waferlike mass of sulphur housed within a casing oi current-conducting material.

12. In a device of the type described, a waferlike mass of chemically pure sulphur housed within a casing of current-conducting material.

13. In a device of the type described, a waferlike mass of sulphur housed within a casing of current-conducting material having one wall thereof perforated to permit said wall to be easily deformed by piercing.

14. In a device of the type described, a waferlike mass of sulphur housed within a casing of heat-conducting material having one wall thereof perforated to form a plurality oi centrally extending easily deformable ilngers, each terminating adjacent the center orf said wall to permit said wall tobe easily pierced at the center thereof with deformation of said fingers.

RUSSELL D. CONBOY.

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