US2663860A

US2663860A - Thermal means of indicating temperature and electric failure

Info

Publication number: US2663860A
Application number: US210566A
Authority: US
Inventors: John N Macinnes; Paul H Gerard
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-02-12
Filing date: 1951-02-12
Publication date: 1953-12-22
Anticipated expiration: 1970-12-22

Description

Dec. 22, 1953 J. N. M INNES ET AL THERMAL MEANS OF INDICATING TEMPERATURE AND ELECTRIC FAILURE 1 Z n e/nar: Job 7 Mac Pa Filed Feb. 12, 1951 f/mes u/ H. ye/"arc! Patented Dec. 2 2, 1 953 THERMAL MEANS OF INDICATING TEM- V 6 PERATURE AND ELECTRIC FAILURE John N. Maclnnes, N ewfields, and Paul H. Gerard,

Newmarket, N. H.

Application February 12, 1951, Serial No. 210.566 6 5 Claims.

This invention relates generally to the class of electric signaling and is directed particularly to a system for use in .connection with building heating and temperature indicating apparatus.

The object of the present invention is to provide a means of indicating temperature change and electric failure in connection with heating apparatus, such as oil burners, to give notice of the failure of electric current controlling the operation of such apparatus and/or the dropping of the building temperature below a desired level.

Another object of the invention is to provide a signal system of the character stated with means for indicating when a furnace is overheated, but functioning normally, without giving a false alarm. it

It is also an object of the invention to provide means for accomplishing the stated results, embodying two signals one of which is active when the heating equipment is operating properly and the temperature is correct, the other signal coming into operation and the first becoming inactive when the reverse conditions prevail.

A still further object is to provide a temperature operated switch in the second or alarm signal circuit which is adapted to effect the intermittent energization of the latter signal when the current fails in the principal circuit.

Still another object of the present invention 0 is to provide means for energizing the alarm signal circuit either by battery or from an A. C. source with thermal switch means controlled by the A. C. for maintaining the latter ready to energize the alarm signal but functioning upon failure of the A. C. supply to put the battery supply in the alarm signal circuit.

The present application is a continuation-inpart of our pending application Serial No. 145,324, filed February 21, 1950.

The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing wherein the single figure is a diagrammatic layout of the electrical system constituting the invention.

Referring now more particularly to the drawing the reference character [0 generally designates a portion of an outside wall of a building.

Exteriorly of the building is located, upon the wall or in any, suitable location, a suitable receptacle 12, in which are mounted, to be clearly seen, the two signal lights l4 and I6, which are preferably, respectively red and green.

Within the building, is a two circuit controlling thermal switch, generally designated l8. This 2 switch comprises thetwo terminals 20 and 22 belonging respectively to the green and red signal light circuits about to be described.

Between the terminals 20-42 is a bi-metal switch blade 24 carrying opposite terminals 26 for selective contact with the signal circuit terminals.

The numeral 28 designates a conductor forming one side of an electric circuit receiving voltage from the twenty-four volt side of the heating equipment controls. The most convenient source of such low voltage is the stack control of the burner. 'Such stack control has such low voltage current available as long as the burner is functioning properly and the power supply is not impaired. Since such stack control is standard equipment used on all automatically controlled and fired heating systems, it is not thought that illustration or further description of the same is necessary.

This conductor 28 is connected to one side of the green signal I6 and the opposite side of this light is connected by the conductor 30 to the switch terminal 20.

The conductor 31 forms the other side of the signal circuit and is electrically connected to the switch blade 24.

Connected across the conductors 28 and 3! is the conductor 32 and resistance 33, the latter being located to heat the bi-metal blade 24, thereby causing the element to fiex in a direction to engage one of its terminals 26 with terminal 20 thereby keeping the light I 6 energized so long as the power remains on.

The value of the resistance 33 is suchthat should the room temperature drop a predetermined amount below normal, the heat from the resistance will be inadequate toprevent the bimetal from cooling slightly, allowing the contacts 2026 to open, breaking the current flow to bulb l6, and causing contacts 22-26 to close and thus complete th circuit for the signal lamp [4 as will be hereinafter apparent.

In the present system use may be made of a battery power source or a transformer connected with the power supply, for energizing the red signal light. Both sources have been illustrated and use is made of a thermal switch or relay, generally designated 34, for the purpose about to be described.

One side of the light I4 is connected by conductor 35 with the terminal 22, while the other side is connected by conductor 36 with one side of a battery 31.

The relay 34.is of the same design' as the thermal switch, or relay, l8 in that it comprises the two

spaced terminals

38 and 39 and an interposed bi-metal switch blade 40 carrying the two contacts 4|.

The transformer 42 comprises the primary and secondary coils 43 and 44, the primary receiving current from th power line, as will be apparent.

The secondary 441s electrically connected with the terminalgiifl by conductor 45 while the other side is connected by conductor 46 with the conductor 36 as shown.

Across the transformer secondary is connected the heater resistance 41 which when.thepower supply is uninterrupted, is heatedinthetrans; former secondary circuit and afiects the bi -metal blade 40 to keep the contactstfi-M closed,

The numeral 48 generally designates a thermal control switch comprising; a,- bi meta-l; switch blade 49 having a contact 50 for coaction with a contact Contact 5| is connected by conductor 52 with the bi metalblade 40 of the relay unit 34i while the blade 49 is connected try-conductor til with the bi-metal-bladei 4:of =the switch- I8 Connecteds between the bi-metalblade 49' and conductor-46 is a resistance heater '53. This oimetal-element 49- is lccatedmn and abscrbsheat from convector of the heating equipment and: is oi such value as'tomaintain the terminals, or contacts, ill-51: closed when thefurnace tem-v perature is not above a selected; or normal, value. When thesurrounding temperature rises. above such-normaivalue, however, thebitmetalzelement lie-affected to causeseparation of thelcontacts Sta- 51. In such event, resulting from overheatingof the heating equipment, thelimit controls would. shut ofiithelcurrent at thecontrolpanel andtboth-lights-would then beout, indicatingat oncetheLcharacter. ofrthetrouble.

The control-switch. 481 in the I present system has an additional function; as. will become. apparent. in. the; following description of operation.

As preniously. stated. the. transformer. 42. will normally heat. resistance 4;! to. keep. contacts 38-4l closed so that all current demands by light; bulbdliwill be.met by the transformer 52.

Ifrthe.linelcurrentshould:fail so that; the trans. former 42 produces no current, the resistance-i1 will; cool; thuslcansingthe bi-metal: blade element; Ail: toppen. contacts 3.8;.41l. and. close. CQl'l-f tactsiisiella sothe batterywill: supply: any. curremrdemands; ofwbulhl4, the. other sde of; the attery. from. conductor as bein connected: by coudpctor .4 with the terminal, cit-contact, 39.

When currentastartse tdflow-i through contacts than, it: will; flow-through-heater 5}, it being understood; thatithroughs thecurrent failure the erminals. on contacts,- are-ac. would, be. closed 50; 'I'herheatina: qflresistance'iawill causethe. birm ta-l: blade is a. pen. the Contacts; sir- 51. stoppin current flQw..-tQ-.the red ligh it... Resistance 53 will then. cool; and the. circuit Will be. rgqlq tldi o. ligh he ,.hl1lb.- Thus thesignal light will be flashedontand cfi;

In the-event ill-$118. closingof theredsienal light circuit,- for some. reason other than power line failure, such, for:- example, as the dropping or temperature to a degree which would permit the bi-metal switchblade-24 to closecontacts 2 2-2 6, the transformer-would maintan control and'supply currentfor the red light. The resistance 53, would; however, talrecfi some current from the light c r uit. nd: t e t; he p ing. and c ofthe contacts 50-51, to flash the lght,as bec ste gt he. n ra iori lig'sy ts n. t e. eve

condition that exists.

of power failure, overheating, failure to ignite properly, very poor combustion, or any other fault that might cause the stack control to cutout, the low voltage current supplied by the circuit conductors 28--3l, is shut off. When the supply of low voltage current is shut 01f, light It is extinguished and magnet I8 is deenergized allowing P ints Z6 22 to'closethus completing the circuit of lines 35and" 36, causing light I4 to become energized and giving warning of the This action would accomplish all that is desired except for the fact that the majorityot heating installations the radiation is inadequate to take care of the output of the furnace. This brings about an overheating condition which is prevented from becoming dangerous by a; limit control, not illustrated, which is a part of the standard oil burner circuit. When such overheating condition occurs the limit control shuts ofi the burner by cutting off the power supply to the stack'control; thuslshutting offithe low-voltage supply; When this. latter action: oc-. curs the reaction, as-fares the present-,signahdevice is concerned, will. be the same. as. a burner. failure in thatthegreen light it: will gooutand thered light lfiiwili come on. This, however, is undesirable inasmuchas overheating is a common occurrence and is. not considered: dangerous. and will correct its-elf: as'soon as-the-furnace. cools off a predetermined.amount.

To eliminate the possibility. of false alarms" which would result from. the. overheating condition, thermal element 48: is installed on. or near, a heat convector so that, inv the event of over-. heating, the bimetallic element 45% will open: con-. tacts 50-51 and will prevent a. complemv circuit from becoming established in the circuit 35-46, so that light It cannot givea false alarm. Thus in the event of overheating, green light IE. will go out butred light i4 Will:not light duetothe action of thermal element 48; Thusif circuit 35-36 is rendered incomplete by either, or both, the action of the'r-mal element-49 or thgbimetal element 24, the light 14 will not beenergized.

It the low voltage supply from the stackcontrol on circuit 28- -31- is shut off due to the stack control cutting out} as a result of: afaulty burner, or is shutoff; due to power line failure, the convector which unit 4flis on or near, wil1 be relatively. cool: and thusthe bimetallicelement 45 will allow contacts 5fi,5-l' to remain closed, thus actionof elementZgi will complete thefcircuit to energize light [4,- which is proper.

h stack. o t l,v h rcinb re referred. s a standard unit as previously stated which is commonly used, l. automatica ly ontr lled a r d heating yestems All: of. h e sta c n r embod a za cltsupnly. hhliisd d from a transformer withnvhichsaid;stacl; concls re. norma ly au ppe lathe. res nt ven cn he ta s control-se ves nl asasg r f rr n sup y. to ac ua e. he. p es nt gi enio hein entiqn tse do not. many was. fiec heo erationQithest ck nirol.

The invention has been thus iiar, described in e ection wit tsutcwi hheatina equipme employing a stacl; controlunit but it"is'also de; signed. r s h aut matic easfircd heate and w e ccm lc ed he circuitwires. 8:31

would be connected to, the solenoid valve circuit,

n s c a mo t gas red heati gunitsare not qu pn w t steck-c ntrols- I We claim;

. 1.. e ns for. ndica in cu r nt a ure a princi al lectrici c itomn isi a two electric signals, a separate operating circuit for each, one of said circuits drawing current from said principal circuit, a thermal relay including a terminal for each circuit and a bi-metal switch blade common to the two circuits for the selective closing of said circuits by contact with one or the other of said terminals, a resistance heater connected across the principal circuit, said heater when energized aifecting said bi-metal blade to maintain the said one circuit closed, and a source of electric potential for the other one of the circuits, said resistance heater being of such value as to be ineifective to influence the bi-metal element suificiently to maintain the said one circuit closed upon depression of the temperature of the surrounding atmosphere below a predetermined value.

2. Means for indicating current failure in a principal electric circuit comprising two electric signals, a separate operating circuit for each, one of said circuits drawing current from said principal circuit, a thermal relay including a terminal for each circuit and a bi-metal switch blade common to the two circuits for the selective closing of said circuits by contact with one or the other of said terminals, a resistance heater connected across the principal circuit, said heater when energized affecting said bi-metal blade to maintain the said one circuit closed, a source of electric potential for the other one of the circuits, and a closed thermal switch in the said other one of the circuits, the last mentioned switch having a heat responsive element of a value to effect the opening of the last named switch upon a rise in temperature of the surrounding atmosphere above a predetermined degree.

3. Means for indicating current failure in a principal electric circuit comprising two electric signals, a separate operating circuit for each, one of said circuits drawing current from said principal circuit, a thermal relay including a terminal for each circuit and a bi-metal switch blade common to the two circuits for the selective closing of said circuits by contact with one or the other of said terminals, a resistance heater connected across the principal circuit, said heater when energized affecting said bi-metal blade to maintain the said one circuit closed, a source of electric potential for the other one of the circuits, and a closed thermal switch in the said other one of the circuits and having a heat responsive element maintaining the last named switch closed while the surrounding atmosphere remains below a predetermined temperature, the last named switch further including a resistance heater connected across the said other circuit and in proximity to the last named heat responsive element to heat the latter when the said other circuit is closed whereby said other circuit will be alternately opened and closed.

4. Means for indicating current failure in a principal electric circuit, comprising an electric signal unit connected in series in said circuit, a thermal switch including a bi-metallic element and two terminals with which the element is adapted to selectively engage, said element and one terminal when in engagement being in series in said circuit, a second electric circuit, a second electric signal unit in series in the second circuit, said bi-metallic element and the other terminal when in engagement being in series in the second circuit, a source of electric potential in the second circuit, a heater element connected across the first circuit adjacent to and for heating the bi-metallic element whereby said element when kept at a predetermined temperature by the heater maintains electric engagement with the said one terminal, said element when below said predetermined temperature opening the principal circuit and electrically engaging the said other terminal to close the second circuit, and a thermal switch in the second circuit functioning to maintain the second circuit closed when the atmospheric temperature around the last named switch is below a predetermined normal.

5. The invention according to claim 4, wherein the last named thermal switch includes a heater element connected across the second circuit and functioning to raise the said atmospheric temperature above said normal when the second circuit is closed and the second signal unit energized whereby the second circuit will be alternately opened and closed.

JOHN N. MAcINNES. PAUL H. GERARD.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,075,314 Flagg et al. Oct. 7, 1913 1,181,419 Williams May 2, 1916 1,653,685 Whittington Dec. 13, 1920 2,439,331 Bean Apr. 6, 1948 2,511,631 Gordon June 13, 1950