US2452942A - Temperature alarm system - Google Patents

Description

Nov. 2, 194 8.

Filed Feb. 26. 1945 K: M. LORD r AL TEMPERATURE ALARM SYSTEM '4 Sheets-Sheet 1 KENNEIH M. LORD. GLENN E. 14.4mm. nwzm'oxs,

Nov. 2, 1948. K, 5 D E V 2,452,942

TEHPERATUREALARM SYSTEM Filed Feb. 26. 1945 v 4 She ets-Shee't 2 7 1 0 Lair E E1 4/22 [Fa/Z0 90 N18 2 8: f w I6 {80 KBNNEmMLbnn GLENN E. WARREN INV BN1 ORS Nov. 2, 1948. K. M. LORD ETA].

TEMPERATURE ALARM $YSTEM 4 Sheets-Sheet 5 Filed Feb. 26. 1945 -Kl'I0/ITH M. LORD 61.5w 5: mummmvroks TIIEIE Arr omvn" Nov. 2 1948. K. M. LORD ETAL TEMPERATURE ALARM SYSTEM 4 Sheets-Sheet 4 Filed Feb. 26. 1945 "mama MLokn GLENN E-WARREN Patented Nov. 2, 1948 TEMPERATURE ALARM SYSTEM Kenneth M. Lord, Canandaigua, and Glenn E.

Warren, Honeoye Falls, N. Y., assignors to Pro- I tect-O-Farm Company, Kenosha, Wis., a part:

nership Application February 26; 1945, Serial No. 579,740

Claims. (Cl. 177-311) This invention relates to alarm systems and is more particularly concerned with systems in which it is desired to transmit a signal to a central point indicating danger due to a change in temperature. The system is primarily designed as a fire alarm signaling system although it may be modified so that one or more stations are established to be tripped by a temperature reaching so low a point as to be considered hazard-' ously close to freezing.

Automatic fire alarm systems for industrial plants have been upon the market for many years but the cost has been considered excessive for the amount of protection afforded except Where. the manufacturing hazard is extremely great as in the case of a combustible product such'as explosives. A very large market exists for an alarm system of this character-where the location of a fire or dangerous heat condition can be rapidly ascertained after the sounding of the alarm. The broad principles of'the system may also be applied to a simplified adaptation which would be useful to farmers; garages, small industrial shops or lofts and the like.

With these considerations in view, it is an object of this invention to provide an alarm system which is simple to install and opera te'will require little or no maintenance and which may be periodicallytested for operativeness with a minimum of trouble,

A further object of the invention'is to provide adetecting unit which is highly portable, may

easily be securedin place at astation'wheredanger of fire or freezing temperatures exists and which may be manufactured cheaply and economically.

It is a further object of this invention to provide a detecting unit which may be adjusted to trip at any predetermined temperature within a range of temperatures.

An additional object of the invention is to provide a temperature detecting system employing a simple electrical circuit which is established and maintained through a series of temperature detecting units by means of a low voltage so that the system can be operated with wire of small size in order to reduce the cost of installation.

Further objects and advantages will appear hereinafter as the description proceeds and will be pointed out in connection with the appended claims.

In the drawings. of which there are three (3) sheets:

Figure 1 is a diagrammatic view showing one modification of the system in its mostsimplified form; v

Figure 2 is a perspective view of a temperature detecting unit as used in the circuit illustrated in Figure 1; I

Figure 3 is a vertical transverse sectional view through the unit shown in Figure 2 and taken substantially upon a plane as indicated by the broken line 33 of Figure 2 and looking in the direction of the arrows;

Figure 4 is a diagrammatic view corresponding to Figure 1 but illustrating a modified type of circuit for more elaborate installations;

Figure 5 is a perspective view corresponding to Figure 2 but illustrating a temperature detecting unit for use in connection with the circuit illustrated in Figure 4;

Figure 6 is a diagrammatic view of a modified circuit in which a lamp bulb is employed in each detectorunit;

Figure '7 is a sectional view of a detector unit buried in a mass of material;

Figure 8 is a partial sectionalview through a modified form of detector unit; and,

Figure 9 is a perspective view of a detector unit employing a lamp bulb for use in the circuit shown in Figure 6.

Referring more specifically to the drawings in which similar parts are designated by the same reference characters and which are to be taken as illustrative rather than as limiting the invention, the system comprising the invention includes a power source I0 which may be the usual 110 volt alternating current power supply generally available in most homes, farms, and factories. Power from this source is led through the primary winding 12 of a transformer indicated generally at [4. The secondary winding I6 of transformer I4 is provided with suflicient turns to insure delivery of 'a potential of approximately v 23 volts which is the functioning voltage of. the alarm system. a

Power from the secondary side I6 of the trans-v former. I4 is passed through conductor 18 and normally closed switch 20 (the purpose of which will be hereinafter described) and thence through bell wire 22 to one terminal 24 (Figure 2) of a temperature detecting unit generally designated at 28. Detecting unit 26 consists of a base 28' peripherally shouldered as at 30 forv the reception of a cap or cover illustrated at 32 in dotted lines. Cover 32 may be made from glass or clear plastic for a purpose to be later explained or could be a metal stamping.

Terminal 24 may be secured to the approxi- 3, mate center of base 28 by meansofa rivet which also fastens in place a conductor 34 supporting one contact 36 of a temperature actuated device.

A second terminal 88 is secured to one end of base 28 by means of a rivet 48 which also serves to anchor one end of a bi-metallic temperature rerapidly burns out and the circuit is disconnected sponsive strip 42 upon base 28. The bi-metallic cular aperture 48 provided in the upper surface of base 28. A rivet 58 extends loosely through plate 46 and base 28 to serve as a bearing for relative rotation between plate 46 and base 28. The upper surface of plate 46 is contoured to provide a cam surface 52 which rises from a low point X evenly and smoothly to a high point Y. The plate 46 is provided with an extension 54 serving as a handle for rotating plate 46 about the axis of rivet 58 to raise or lower the bottom, or relatively fixed, contact 36. The outer end of handle 54 may be provided with a bench mark 56 and the surface ogshoulder 38 may have graduations stamped thereupon as at 58 to indicate the extent of the adjustment. Handle 54 extends outside of base 28 through an arcuate notch 68.

An alternative method of adjustment involves the support of the free end of conductor 34 upon the upper surface of a knurled edge plate I88 which plate may in turn be internally threaded to co-act with a threaded post I88 supported from base 28 as in Figure 8.

In the normal unit the bi-metallic element 42 is so shaped and proportioned that when the lower contact support arm 36 lies upon that portion of the cam plate indicated at X the contact points will remain in circuit establishing position at all.temperatures up to 180 F. Rotation of the cam plate 46 counter-clockwise as viewed in Figure 2 results in movement of the lower contact '36 upwardly and a consequent raising of the separating temperature of contacts 44 and 86. In the modification shown in Figure 8, raising the plate I88 by threading it upwardly upon post I 88 will similarly raise the temperature of release of the bi-metallic element 42.

Bi-metallic element 42 may also be reversed so as to provide for maintenance of contacts 36 and 44 in circuit establishing relationship at all for a purpose as will soon appear.

Another form of tell-tale device which might be employed would involve the use of an incandescent bulb I88 in place of the high resistance wire, as shown in Figure 9. so selected as to cause a substantial variation in the circuit current whenthe' contacts 86 and 44 are opened. The illumination from the incandescent lamp III in this form serves to indicate which detector has reached a danger point. Also, when using a lamp, replacement of the detector unit after each circuit interruption-would not be necessary.

In the event a lamp bulb I88 is used in place of a self-destroying wire, it is contemplated that the lamp will be connected across the terminals as shown in Figure 6 and will provide so high a resistance as to cause a reduction in the circuit current to so great an extent that insuflicient current will flow to maintain the relay in its raised position;v thus closing switch I6 and energizing bell circuit I8, 88 and 82.

Continuing with the electrical system illustrated in Figure 1; a conductor 66 connects the unit 26 in series to a second unit 26' and a third unit 26" is connected in series by conductor 68 to second unit 26'. As many units 26, 26', 26", etc., as may be desired arethus connected in series and the final unit in the series is'connected by means of a conductor I8 through the winding of a solenoid or relay 12 to the secondary I6 of transformer I4. Relay 12 functions in its nor-v mally energized condition to .maintain switch I6 in open position.

Switch I6 is inserted in a circuit including conductors I8 and 88 for establishing an electrical circuit to a bell 82.

It will thus be seen that while the circuit through the units 26, 26', 26", etc., remains es-,, tablished the bell circuit is open because of relay I2 holding switch I6 open; When, however, the

temperatures, above a predetermined minimum, I

say 32 F. The separation temperature of such a unit'couldalso be controllably varied.

While not a necessary adjunct to the operation of the system, a convenience measure includes an extremely high resistance wire 62 of very small size which may be soldered across the terminals 24 and 38. A central portion of wire 62 indicated by zig-zag lines in Figure 2 may be secured to the upper surface of base 28 by a paste (in which a combustible smudge forming element is mixed). With contacts 36 and 44 in normally closed position, the current flowing through the device passes through these contacts; when, however, the contacts are opened by a temperature change the entire current must pass through the has reached a danger point. The resistance wire circuit "through the temperature detecting units is broken as by separation of the contact points 86, 44, relay I2 is de-energized to close switch I6 to establish the bell circuit which audibly warns of a break in the circuit signifying that a dangerout temperature exists which warrants investigation. An inspection of the units can then be made for evidence of smudging or blackening or lighting of the incandescent bulbs.

A switch 28 in the form of a circuit-opening push button may be provided in the detector circuit for periodic testing by opening the detector circuit.

Referring briefly to Figure 2, the base 26 may be provided with cars 84 which are perforated to permit fastening the units by means of nails or other fasteners in locations considered dangerous from the standpoint of fire or freezing temperatures. It may be considered desirable not to secure the detecting unit 26 in place but simply to bury it as shown in Figure 7 in a mass of material I83 such as green or. uncured hay, ensilage or other material, which might present a fire hazard as source of spontaneous combustion. In this connection the detector may be sealed inside an impervious case I84 of glass,

metal or other suitable material closed by a plug I85 through which connectors 66' and 68' may pass, to prevent the entry of foreign matter. For detector units buried in a mass I 88 a provision couid be made to have the incandescent bulb I88 mounted in a visible location as on an external support I82 secured to a beam I81 as Referring now to Figure 4 illustrating a slight- 1y more elaborate system for signalling, the circuit will be seen to comprise a main power input IIO of 110 volts alternating current which passes through the primary coil II2 of a transformer II4. A secondary coil II6 of the transformer is arranged to provide a potential of approximately is anchored by rivet I40. Rivet I40 also tunetions to connect terminal I36 to bi-metallic element I42. Conductor I66 leading to the second detector unit I26 extends from the orimped end of terminal I38.

The terminal I38 is also extended beyond the rivet I40 as at I to provide a connection to which one terminal I43 of a resistance I45 may be secured as bysoldering. The other terminal I41 of resistor I45 is secured to a terminal I40 attached by rivet I5I to base plate I28. A wire I53 serves as a conductor to connect lent terminals I49 in each of detectors I26, I26. and I26", etc., to a terminal of a milliammeter ISL-the opposite terminal I59 0f milliammeter I51 being connected to a constant voltage direct current source such as a battery IBI. A conductor I63 connects the opposite side of battery I6I to a normally open single pole single throw switch I65, having its closed end connected to conductor I 22 of detector circuit. 4

The balance of the detector circuit is similar to that illustrated in Figure 1 extending through conductor I10 to relay I12 for operating the bell circuit closing switch "4 (which in this instance is illustrated as operated from a 110 volt power source) and finally through conductor I61 to a normally closed single pole, single throw switch I69 which connects to secondary H5 to complete the circuit Switch I69 is connected to switch I65 by means of a mechanical, non-electrical conducting link III in such a manner that when switch I65 is closed, switch I69 is opened and vice versa. The I switches I55, I60 are'shown arranged to be manually operated but could. be actuated to close switch I65 and open switch I69 by the movin member of relay -I12 when switch I14 is closed as shown in Figure 4a.

Assuming the system to bein operative condition as shown in Figure land one of the detector stations I26 to'be tripped-as byexcessive heat or cold, the detector circuit being thus opened will stop the flow of current to relay I12 closing switch I14 and energizing the hell or alarm circuit. The operator thereupon pushes the button to open switch I69 and close switch I65 to energize the milliammeter circuit (in the case of the manually operated detector system).

Since the resistances I45, I45, I45", etc., are connected in the milliammeter circuit in parallel,

and since the amount of resistance in the line is controlled by opening and closing of contacts I36 and I44 in each unit, I26, I26, I26", etc., the resistance of the entire circuit with any one unit having its contacts open can readily be computed using "the formula: 1/R=1/R'+1/R"+1/R",

etc.

Knowing the computed resistance (with conthe equivav shown in Figure 7 so that the visual recognition I of thei alarming detector would be iacilitated.

stant voltage) with any one 01 detector resistances I45, I45, I45", etc.,

an easy matter to calibrate the scale of the milliammeter in such a way as to indicate directly the station ,or stations from. which the alarm is proceeding. For purposes of standardization and ease of installation the resistance inserted in the detectors may be equal. With equal resistances in each detector the division of a milliammeter scale, is equal.

. Assuming in a three station circuit as shown in Figure 4 that resistance, I is 1000 ohms, re-

through the conductors will be negligible and the current flowing will be- .0 ampere with station I26 open .006 ampere with station I26 open .0l2 ampere with station I26" open These positions can readily be marked on the dial 0! a milliammeter.

It might be desirable in some installations to have a resistor only every ten stations, for instance. In this manner the milliammeter reading would indicate that any one of a certain group of detector units was alarming, rather than indicating exactly which unit was alarming. By doing this many more detector units could be provided for on a single milliammeter scale.

While the invention is described in consider-' able detail, the foregoing description is to be taken as illustrative and not limiting. All equivalents falling within the scope of the appended claims are expressly included as a part of this invention.

We claim:

1. In a temperature'signaliing system comprising a signalling circuit, a central alarming station and a, plurality of temperature detecting stations connectedin series to establish a-detector circuit, said detecting stations each including a normally-closed set oi. contacts, a normally open secondary indicating circuit paralleling said detector circuit including an ammeter and connected to said detector circuit through resistances at each of said detecting stations, means operated by the opening of said detecting circuit for establishing both said indicating and said signalling circuit for simultaneously disconnecting said detector circuit and establishing said indicating circuit through'said resistances remaining when the contacts atone detector staton are open to aflect'said'ammeter for indicating the station affected.

2. In a temperature signalling system for indicating at a central station the occurrence, at any one of a plurality of remote locations, of a predetermined temperature-condition, the combination of an alarm mechanism at said central station including a relay, an alarm device, an

energizing circuit for said alarm including a con-, tact for said relay, and means operative upon releaseoi said relay for placing said contact in closed position, a. first source of current connected in series with said relay, a contact device at each location including a normally closed contact adapted'to open upon occurrence ofsaid predetermined temperature condition at its location and a permanent and constant connection from each location to circuits connecting said permanent connections parallel to each other across a switch,an ammeter and a second source or current of constant voltage, said closed coneliminated, it will be 7 tacts being connected in series across said firs source of current and relay to keep the latter normally energized, each of said circuits having a predetermined resistance different from those of all other parallel circuits, and means under the control of the operator for closing said ammeter switch and opening .the series circuit through said locations and said first source of current.

3. In a temperature signalling system comprising a signalling circuit. a plurality of temperature detecting stations connected in series across a first source of power and through'a relay to establish a detector circuit, said. detecting stations each including normally closed contacts adapted to open upon occurrence of predetermined temperature conditibn, a normally open indicating circuit in parallel with said detector circuit having constant and direct connections through resistances to said detector circuit at regular intervals at said detecting stations, said indicating circuit including a second source of power, an ammeter and a switch, means including said relay operated by the opening of said detector circuit to simultaneously close the signalling circuit and close said switch of said indicating circuit and place it across said second source of power.

4. In a temperature signalling system comprisiia'g a signaliingcircuit, a plurality of temperature detecting stations connected in series across a first source of power and through a relay to establish a detector circuit, said detecting stations each including normally closed contacts 'sadaptcd' tc='open upon occurrence 01a. predeter-v mined temperature condition, a normally open indicating circuit in parallel with said detector circuit but constantly and directly connected thereto at said detecting stations through equal resistances, said indicating circuit including a second source of power, an electrical measuring instrument and a switch, means including said relay operated by the "opening of said detector circuit for establishing said signalling circuit,

Number and operator controlled means for closing said ing a signalling circuit, a plurality of tempera-- ture detecting stations connected in series across a source of power and through a relay to establish a detector circuit, said detecting stations each including normally closed contacts adapted to open upon occurrence of a predetermined temperature condition, a normally open indicating circuit in parallel with said detector circuit having constant and direct connections through resistances to said detector circuit at said stations, a switch for closing said indicating circuit, a second switch connected with said first switch and adapted to open said detector circuit when said indicating circuit is closed, said indicating circuit including an ammeter calibrated to indicate the point of interruption of said detector circuit, and means functioning upon in-,

terruption of said detector circuit to establish said signalling circuit.

KENNETH M. LORD. GLENN E. WARREN.

REFERENCES "CIT ED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain 1895 Great Britain 1904 Great Britain Oct. 17, 1935 Number

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