US1686286A - Temperature-actuated electric control device - Google Patents

Description

5 Sheets-Sheet l. E. MCCABE TEMPERATURE ACTUATED ELECTRIC CONTROL DEVICE Filed Nov. 5, 1925 Oct. 2, 1928.y

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Oct. 2, 1928.

I. E. MCCABE TEMPERATURE ACTUATED ELECTRIC CONTROL DEVICE I5 Sheets-Sheet Filed Nov. 5, 1925 EWI 1 mw J I mm mm l. mm

TTORNEYS.

oct. 2, 192s. 1,666,286

l. E. MccABE l TEMPERATURE ACTUATED ELECTRIC CONTROL DEVICE Filed Nov. 5; 1925 5 sheets-sheet 5 i6 N I I xn E a., Q4

TORNEYS.

Patented ocr. 2, 1928. l

UNITED STATES IBA. E. vIIIIICCABIEQCIIF CHICAGO, ILLINOIS.

1,686,286 PATENT .o1-"F1os,

TELIPERATURE-ACTUATED ELECTRICCONTBOL DEVICE. I

Application filed November 3, 1925. Seria/1 No. 66,518.

This invention lrelates to improvements in electrlc control devlces and more particularly to a temperature actuated electric .control dedescribed as adapted for use in an electricallyv `operated furnace or heatproducing device and which is particularly advantageous as a part of an electrically operated liquid fuel` burner system for domestic purposes, although this invention contemplates other uses of this control. It is a further object to provide a device of this character which is particularly adapted in electrically operated domestic liquid fuel burning systems to' act as a safety device for such systems. The particular embodiment of this invention as illustrated on the accompanying sheets of drawings and hereinafter described is designed to be applied tothe stack or pipe leading from the furnace heated by the domestic liquid fuel burner system which will operate to break the electricl circuit incase the liquid y -fuel burner does not ignite or if the flame from the burner fails at any time after ignition.

In the drawings:

Figure 1 is a view ln't-he front elevation of the casing, with the cover removed, illus- 'ti-ating an.embodiment of this invention and illustrating in diagram the wiring between this device and the electric motor.

Figure 2 is a\'view in horizontal section taken on the line 2-2 of Figurel looking 1n the direction of the arrows.

Figure 3 is a view in the side elevation of Figure 1 with parts broken away and partly in section.

Figure 4 is an enlarged detailed view in central vertical section of the heating element illustrated in Figure 3.

Figure 5 is a view in diagram illustrating the application of a `modified form of this control actuating the electric connegtions between an electric motor and the source of commercial current.

In the embdiment of this invention as illustrated in Figures l to 4. inclusive, the electric I circuit to the motor is closed or opened by the tilting movement of a mercury tube s'witch l, which is shown mounted on a pivoted carrier plate 2, withtwo terminals adjacent each other and near one end of the' tube so that when the tube is tilted in that direction the vmercury will accumulate` in that end and' close the circuit through such terminals and when tilted' in the opposite direction thefmervcury-Will flow'away from said terminalsy and break the circuit therethrough. As shown in F igu'res 1 to 3 the tilting plate 2 carrying-'the mercury tube is provided with a counterweight 3 which will normally tilt the tube `to the open or circuit-breaking position. .The

p late 2 carrying themercury tube is'also 'rovlded with a dependlng projection in the orm lof a pawl 4 adaptedto engage in the teeth of a ratchet wheel carried by a sleeve 6 havmg a detachable connecticn'with an'enclosed shaft 7 whereby the mercury switch tube may be tilted into the lclosed position and held therein againstthe counter weight by engagement ofthe pawl with the ratchet and whlch when the ratchet carrying sleeve becomesdetached from the shaft will allow the counterweight to cause the ratchet to be rotated by the pawl releasing the tilting plate 2 and moving the switch tube into the open position.

- As illustrated in Figure 4, the sleeve 6 carrying the ratchet Wheel 5 is of greater inside Adiameter than the outside diameter] of the fixed shaft 7 which it surrounds and thelower end of the sleeve is receivedin a cup shaped enlargement of said shaft as shown. The space between the inner circumference of the sleeve and the outer circumference of the shaft is filled with solder which will normally secure the sleeve in the fixed position upon the shaft. The shaft, 7, is preferably constructed ofbrass or other heat transmitting metal anid is rigidly secured upon a bracket 8 of similar metal. This bracket has a depending portion 9, forming one end of the heat generatmg unit which when actuated to generate heat willtransmit the heat so generated through the bracket to the shaft and melt the solder allowing the sleeve to be rotated about the shaft. I

The heat generating unit is preferably composed of two or more series of loosely mounted superimposed graphite disks 10 arranged side by side in a `cylinder 11 of lavite or other electric insulating material with one end bearing against the depending heat transmitting bracket 9, and the other end bearing against a movable block l2 held in place and movable between four posts 13 securing the heat transmitted bracket to the back of the instrument casing. A sheet of mica or other electrical insulating material 14 capable of transmitting heat is interposed between theranged to project from the instrument casing at the back of the movable block 12 and be secured to the stack or pipe 17 extending from the furnace to the smoke stack or chimney. Arranged inline with the center `of the movable block 12 is a tubular member 18 of metal'adapted to extend within the stack and be secured to the instrument supporting sleeve 16, preferably by means of a. vsplit sleeve 19 secured to the said supporting sleeve 16. -Within this tubular member 18, is arranged a metallic rod 19, which is secured to the extremity of the tubular member within the stack. It is preferable to construct the tubular member 18 and .the rod 19 of metals of different co-etlicients of expansion, lsuch as constructing the tubular member of iron or steelv with the enclosedl rod of brass, copper, or aluminum, whereby the heat arising from the furnace and passing through the stack about the tubular member will cause the same to expand and cause the enclosed metallic rod to expand to a greater extent. In line with this rod 19, and the center of the metallic block is mounted a movable plunger 2() having a reduced portion 21 adjacent its end nearest the movable block forming shoulders on each side thereof which reduced portion is mounted to extend through a plate 22ysecured by the four heat supporting unit posts 13 to the back of the instrument casing which plate will be engaged by the shoulders and limit the movement of the plunger toward and away from the movable block. The expansible rod- 19 carried within the tubular member and secured at one end thereto-is provided with a reduced free end or a small concentric rod 23 secured thereto the free end of which is adapted to slide within a recess 24 in the adjacent end of the plunger 20; The upper ortion of the plunger adjacent its free end 1s cut away to receive a clamping member 25 adapted to bear upon the upper side of the reduced end 23 of the rod 19 which clamping member is held under tension by a spring 26 carried upon the upper side of the plunger, the tension of which is adjusted by a bolt and nut passing through the plunger. As seen from Figure 4 the movable block 12 is provided with a screw threaded abutment 27 passing through the center thereof and adapted to engage lthe adjacent end of the plunger 20 so that by adjustment of this abutment the amount of pressure applied by the forward movement of the plunger before its rear shoulder is engaged by its supporting plate transmitted through the movable block to the series lof graphite disks may be regulated. The tension of the spring clamp 25 in engagement with the free end of the expansible rod 19 is such that, if the plunger 20 be retracted'with the forward shoulder in engagement with the supporting plate with the expansible rod in its contracted position and the tubular member within the stack is subjected to an increasing temperature, the first expansion of the rod will push the plunger 2O forward against the movable block 12 transmitting pressure upon the series of graphite disks 10 untilfthe rear shoulder of the plungerVv engages its supporting plate, and a continued expansion of the rod 19 will cause its reduced end 23 to slide under the clamping member 25, and upon the contraction of the rod it will first withdraw the plunger 2O until its forward shoulder engages its supporting plate and then con- .tinued contraction will cause the reduced end of the rod to slide under the plunger carried clamp. A

As shown in Figures 1 and 3, four'binding posts, 28, 29, 30, and 31, are provided upon the rear of the instrument casing above the mercury tube switch. The two upper binding posts 28 and 29 are secured by flexible leads 32 to the terminals of the mercury tube switch. The left hand binding post 280i the upper series is connected by a lead 33 to the outermost graphite disk, of one series, the rearmost graphite disk of that series being connected by a lead 34 to thecorresponding Y `rearmost graphite disk of the other series and the outermost graphite disk of said latter series is connected by a lead 35 to the lower left hand binding post 30. From the diagram of the wiring shown in' Figure 1, it is seen that one line of the outside source of electricity or commercial circuit is connected to the upper right hand binding post 29 of theinstrument casing and the other line of the commercial circuit is connected to one pole of an electric motor, M, the other pole of which is connected to the lower left hand binding post 30 onN the instrument casing.

The mercury tube jswitch is shown in the' closed position so that the circuit vfrom the outside will pass through the upper right hand binding post 29 through the lead 32 therefroml to the switch, the mercury within the switch, the lead 32 from the other terminal of the switch to the upper left hand binding post r28 and from thence through the lead 33 to one series of the graphite disks, through that-series of graphite disks, through the lead 34, therefrom to tlie other series of Losanna graphite disks, through the latter series of graphite disks to the lead therefrom to the lower left hand binding post 30, and from thence through the motor, M and back to the source of commercial current. It is readily seen that when sufficient heat is generated bythe current passing through the graphite disks to melt the solder to release the ratchet wheel, the counterweight will tilt the mercurytube switch to cause the mercury to flow to the opposite end and thereby break the electrical circuit through the switch which will also break the circuitfthrough the motor.

In the electrical art it is' recognized that series of superimposed graphite disks, such as shown'and described, will transmit electricity and generate heat `in proportion to the amount of pressure applied to suchfseries of disks, the greater the pressure the greater ease the current passes through the series and the less amount of heat generated. By a proper adjustment of the abutment 27 of the movable block'12 of the heat unit shown and described, an amount of pressure can be applied to the series of graphite disks to normally generate heat sufficient tor melt the solder normally securing the ratchet wheel in the xed relation to the immovable shaft and by providing a proper number of graphite disks in each series lsufficient pressure vmay be applied thereto by the normal extended movement of the plunger 2O to allow the current to pass through the disks Without generating sullicient heat to melt the solder.

By the construction shown in Figures 1 to 4, it will be readily seen that as soon as suiiicient heat has passed by the tubular member 18 Within the stack to move the plunger 20 it compresses the graphite disksksuiiiciently to prevent'the soldenmeltingand when such heat ceases or diminishes sufficiently to cause contraction of the metallic red 19 suchpressure upon the disks will be immediately released and sufiicient heat will be produced by the disks which will be transmitted through the heat'. transmitting bracket 9 to the post 7 within the ratchet wheel sleeve '6 to melt the i' solder, allowing movement of the ratchet wheel whereby the counterweight 8. through the pawl 4 on the mercury tube tilting plate 2 will rotate the ratchet wheel 5 and tilt the mercury tube' switch to the opposite or open position. v y e l As above stated, this device may be most advantageously used to control .electric circuits for actuating' an electrically operated domestic liquid fuel burner and by proper ady justments the closing of the circuit, with the ell mercury tube switch in the closedposition, will'ignite and operate the domestic burner and the heat arising from the burner flame will besuiiicient to expand the metallic rod to compress the graphite disks before sufficient heat has been generated to melt the solder holding the ratchet wheel in the fixed relaltransmitted to relieve such pressure upon the graphite disks causing sufficient heat to be generated thereby to quickly melt the solder and release the ratchet wheel to break the motor circuit. f v

In the modification shown in Figure 5, the Variation of pressure upon the series of similar graphite disks 10 is employed in connection with tlie'type of mercury tube switch shown and described in my prior application filed March 30th, 1.925, Serial N o. 19,310, in which a similar mercury tube switch 1, is mounted upon a tilting plate 2, pivoted to the rear of the instrument casing-provided with a Lsimilar counter weight 3, upon theswitch carrying plate and pawl and ratchet- wlieel attachment 4 and 5 similar to that heretofore described, with the difference that the fixed post 7 within the ratchet sleeve 6 is heated by a coil of resistance wire 40 wrapped thereabout as shown in Figure 5, instead of the heat being transmitted by the supporting bracket 9 as described in connection with Figures l to 4. A separate mechanism in a casing is provided to be attached to the stack or pipe 17 leading or smoke stack, including a tubular 'member per, brass, or aluminum, adapted to be ex- 'tended in the stackor pipe andsecured thereto by a flanged plate 42 as illustrated. A rod 43 of steel, or iron, or less rapidly expansible metal, isv secured to the end of the tubular member Within lthe stack, the free end of which rod passes through a sleeve 44 having a flange 45 about one end adapted to be secured upon the inner side of the mechanism casing with the exterior portion 46 of the sleeve reduced 'and adapted to slidev within the tubular member and prevented from -rotation thereabout by a pin 47 passing through this reduced portion, through a slot 48`in the rod, and 'through opposite disposed slots 49 in the surrounding tubular member with the ends of the pin engaged in a split sleeve or clamp 50 arranged about the exterior of that end of the tubular member 41. vThe end ofthe rod within the instrument casing passes through and is adjustably secured to a pressure plate 51 extending over one or more se-l ries of graphite disks, 10 containedy within cylinders 1-1 of lavite or other insulating material, which cylinder engages the supporting sleeve flange 45, within the instrument case and are electrically insulated therefromby a disk or sheet 52 of mica. Secured to the ade jacent side of the pressure plate 51a pressure member 53 is provided which is adapted to engage the series of graphite plates there-v under Within the insulating cylinder 11 at various pressures and is insulated from such series by a sheet or disk 54 of mica or other insulating material.

from thefurnace to the chimney llO The slot 48 within the rod 43 allows a little play within the supporting sleeve 44 so that upon heat of increasing temperature passing about the tubular member 41 Within the stack will first cause the tubular member 41 to more rapidly expand than the rod 43 oontained therein which will cause a pulling action upon the rod which Will exert pressure through the pressure plate 51 upon the series of graphite disks 10 until the left hand end ot the slot 487m the rod engages the sleeve centering pin 47 and further expansion of the tubular member will cause the instrument supporting sleeve 44 to be drawn within or the surrounding tubular member 41 against the tension of thesurrounding clamp 50 so that as soon as the temperature of the stack diminishes the tubular member will begin to contract and the contraction will cause im` mediate movement of the rod in the opposite direction, thereby releasing the pressure upon the series of graphite disks, and further contract-ion will cause the instrument supporting sleeve 44 to be pushed outward from the end otl the tubular member against the tension of the pin supporting clamp 50. It will be seen in Figure 5 that the uppermost instrument casing is provided with three binding posts 55, 56, and 57, the upper one 55 of which is connected by a lead 58 to one end of the upper series of graphite disks with the other end of such series connected by -='a lead 59 to the middle binding post-56 which in turn is connected by a lead 60 to one end of the second series of graphite disks with the other end of such series connected by a lead .61 to the lower binding post 57. In the instrument casing at the bottom of Figure 5 it is seen that the two uppermost binding posts 62 and 63 are connected by flexible leads 64 to the respective terminals at one end of the electrical tube switch 1 adapted to be placed in the circuit by the mercury accumulated at i that end of the tube. The upper right hand binding post 63 is connected by a lead 65 to the upper of the lower series of binding posts 66 and 67 which in turn is connected to the resistance wire 4() passing about a depending extension of the shaft 7 with the other end of such resistance wire 40 connected to the lower binding post 67 of this series. From the diagrammatical illustration of the wiring shown on Figure 5, it is seen that one line of the commercial source of' electricity is connected to' the upper left hand binding post 62 so that the current passing therethrough will pass through the mercury tube switch, in the position illustrated in Figure 5, to the other upper left hand binding post 63 and then through lead 65 binding posts 66 and resistance Wire 40 about the heating element of the solder retaining ratchet wheel to the lowermost binding post 67 of that series which in turn is connected to one pole of an electrical motor M, the other pole of which is connected to the other commercial line. The temperature actuated control mechanism vin the instrument casing illustrated above the switch mechanism casing is connected in parallel with this circuit by a connection between the upper binding post 55 in the upper instrument casing to theupper binding post 66 of the lower series in the lower instrument casing and by a connection between the lower bindingposts 57 and 67.

As in the first instrument described the control instrument can be so adjusted that when the motor is started with the mercury tube switch in the position shown in Figure 5, the commercial current will pass through both the heat generating resistance Wire 40 and the series of graphite disks 10 so that if the. tubular 41 member remains stationary sufficient heat will pass through the resistance wire 40 to melt the solder and release the mercury tube switch to be acted upon by its counter weight to break the circuit through the motor. Under normal conditions in a domestic liquid Jfuel burner system the closing of the circuit to operate the motor will also ign'ite the burner flame and the heat arising therefrom will cause the tubular member 41 to expand suiiiciently to create enough pressureupon A Ywill pass through the resistance wire which will be of sufiicient intensity to generate suiicient heat to melt the solder and release the mercury tube switch to break the motor circuit and causes the burner mechanism to cease operation.

What- I claim is:

1. In atemperature actuated electric coni trol device including an electric'switch, means normally acting to hold the switch in open position, detachable means for holding the switch in closed position releasable by heat generated by the electric current, and a temperature actuated compression means for varying the turrent passing through said heat generated means.

2. In a temperature actuated velectric control device including an electric switch, means normally acting to hold the switch in open position, detachable means for holding the switch in closed position releasable by heat generated by the electric current, and a temperature actuated compression means adapted at normal temperature to actuate said means to release said switch.

3. In a temperature actuated'electric control'device including an electricswitch, means l -l normallyy acting to 'hold the'switch 'in open position, 'detachable means forj holding switch in' closed position releasable by .heat generated by the electriccurrent, anda temperature actuated? compression means adapt- Aed` upon an increasing of 'temperature toa predetermined, degree above" normal to hold the switch in closed lpositioni 4. -Inv a4 temperature actuated electric control device including an electric switch, meansA position, detachablemeans `forholding the .switch in closed positionireleasable by v'heat generated-by the electric currentrand atem-v perature actuated means adapted upon an increase of temperature toa predetermined degree above normal to hold' the switch Ain closed position andjallow of furthery movement'ofsaid actuating means-.upon an increase of temperature above said .predetermineddegree. p Y

1 y 5. In a temperature actuated electric control device 4including an' electric switch, means normally acting to hold the" switch-in open I 'generatedby the lelectric current,- a temperature actuated compression means adaptked upon ap increase ofl temperature to a predetermined degreeabove normal to hold' the switchin vclosed position and allow of free movement of said actuated means upon an increase in temperature there above and immediately upon a lowering of temperature from any degree to actuate said means to open said switch. l

f 6. Ina temperature actuatedelectric conl trol device including an electric switch,'m ean's f the f termined amoun'tfof l perature actuated compression means adapt' ed at normal temperature to generate suiii-' position, detachable means for holding theswitch in closed position releasable by heat normally acting to open said switch, detach-` able means for holding the switch in closedtransmitting a predeposition'releasable b y heatthereto, and a temcient heat to release said holding means.

7. In'atemperature actuated electric control' device including'an electric switch', means nori'nally*acting-to open saidswitch, detach? ableinean's-or holding the switch in .closed determined amount of heat thereto, electric infeans in the. circuit with said switch adapt! ed to apply *heatl to said v detachable means, a pressure operated means in said circuit, a temperaturel control-operating means for actuating said pressure operated means togenerate suiicient heat to ing means.

' S.' Ina temperature actuated electric control device including an electric switch', means normally acting tovhold the switch in the release theswitchholdclosed'position adapted` to releas'esaid means upon the application of heat, electric heat lgenerating means .in thel circuit with said switchknormally adapted to generate sufticlent 'heat to release vSaid means, pressure operated means tor reducing the amount oheat-be'- j low that required torelease the switch, means -actuatedby changes in temperature to' vary theoperation' of said pressure means, includy ing a plural-ity of superimposed*graphite` disks form-ing a part of the heat generating means in circuit with said switch, and a-tliermost'atic element adapted to. apply variable pressure thereto. v

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