US2318699A

US2318699A - Temperature responsive electric switch

Info

Publication number: US2318699A
Application number: US388424A
Authority: US
Inventors: Ira E Mccabe
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-04-14
Filing date: 1941-04-14
Publication date: 1943-05-11
Anticipated expiration: 1960-05-11

Description

l. E. MCCABE May ll, 1943.

l t e kan uw t e e .n S H2 C T I w s C M1 T ou El m. ,n E V In w mA. mw nu MF U T A Dn E m E T INVENTOR. /RA E. MC CABE A T'VORNE Y.

May ll, 1943. l. E. MCCABE 2,318,699

TEMPERATURE RESPONSIVE ELECTRIC SWITCH Filed April 14. 1941 2 sheets-sheet 2 28 27 AQ' gmx@ 4 INVENTOR. /RA E. Mccn/L' ATTORN E Y Patented May 11, '1943 'rmanama nasrouslva ELECTRIC swrrcn Ira E. McCabe, Chicago, Ill. Application April 14, 1941, semi No. sss,4z4

(ci. zoo-13s) 9 Claims.

This invention relates. to improvements in electric switch mechanisms and more particularly to the structure of temperature responsive electric switches. 1

It is an object of this invention to provide a switch of the character described'and. illustrated in this applicants rprior Patent No.

1,834,288, dated December 1, 1931, wherein the parts are so constructed that compensating adjustments may be made at the factory to insure consistent manual adjustments in the eld. Electric switches of this type are designed to control the operation of domestic heating systems, as well as for industrial purposes with some of the more common uses being to limit temperature within furnaces, bake ovens, 'stack pipes and ducts and for the control of dampers and circulating fans employed in warm air heatingsystems. Devices of this character when installed in connection with electrically operated and controlled heating systems have the thermally responsive element extending into the stack or pipe leading from the furnace or heater to the chimney or into the bonnet if the heater is a warm air furnace or in warm air ducts running from the furnace, withV the instrument or switch casing supported on the exterior thereof.

Because of the various temperatures at which the device may be desired to operate due to the variety of uses to whch it may be put and its location when installed, it is desirable for such a device to be made operable over a wide temperature range and adjustable over that range in Vsuch a manner as will permit the adjustment oi the high and low operating points independently of each other. Furthermore .when such devices are applied to domestic heating apparatus, the compact and improved appearance of the heating plants being made today necessitate or make desirable the use of controlling devices, attached thereto, to be small and compact'to fit into limited space and to harmonize limited movement of the. temperature responsive actuating means beyond the predetermined adjusted temperatures which limit the opera- I tion of the switch thus protecting the temperawith the general design of the new type of boilers and furnaces. It is also'desirable that when these dev'ices are of the adjustable type that the adjustments be made upon the exterior of the enclosure for the operating instrumentality.

It -is thus an object of this "invention to provide a small and compact temperature actuated switch of the character and for the uses described in which a simple form of adjusting means permits the adjustment of the operating points to be made upon the exterior of the switch enclosure. It is a further object to provide a switch operating structure permitting unture responsive means and preserving the calibration of the device. It issti11 'a further object to provide means to compensate for variations in the manufacture of helical bi-metallic coils employed as the temperature responsive actuating means, when calibrating the device for service. Still another object resides in the lprovision of a manually operated locking means for locking the switch in closed position, in those forms of devices which open the switch on falling temperature, and to automatically release the locking means when the temperature has risen above the low setting of the device sufllciently to maintain the switch closed while temperature remains above the low setting.

With these and other objects in view reference is made tothe accompanying sheets. of drawings illustrating a preferred form of this invention with the understanding that minor changes may be made without departing from the scope thereof.

In the drawings:

Figure 1 is a view in side elevation of a preferred form of this invention with parts broken away illustrating the' adjusting and operating mechanism in elevation.

Figure 2 is a front view of Figure 1 with the front cover removed.

Figure 3 'is an enlarged fragmentary detail view in vertical section taken on the line 3 3, Figure 2, illustrating some parts in elevation.

l Figure 4 is a detail view in perspective of parts of the switch operating mechanism as connected to the operating shaft. s

Figure 5 is a detail view in perspective illustrating the means of adjustment between the operating shaft and parts actuated thereby.

Figure 6 .is a detail view in elevation, with parts brolnen away, illustrating the position assumed by the parts when the 'thermal element in response -to temperature changes has oscil` ing the positions ofthe toothedwheel adjacent the disk in dot and dash lines.

Figure 11 is a detail View in elevation illustrating the' stop 0nl the switch carrier arm and notch on the underside of the front plate to limit the travel of the said arm, showing the position assumed at one end of travel in full lines and at the other end of travel in dot and dash lines.

Figure 12 is a View similar to Figure 11 illustrating the lock .latch in engagement with the stop on the switch carrying arm in full lines and the position of the lock latch when disengaged in dot and dash lines.

In the embodiment of this invention illustrated upon the accompanying sheets of drawings,

the thermally responsive element is shown in Figure 1, as a helical coil I of bi-metallic metal,

one end of which is secured to a cylindrical tube 2 adapted to be inserted -through the stack or casing of a furnace or heater employing an electrically operated and controlled fuel burning mechanism. The tube 2 is preferably held in position in the stack or casing by an adjustable clamp member 3. The exterior end of the tube 2 is rigidly secured to The outer or free end of the thermal coil I is rigidly secured to the end of an operating shaft 5 which passes through the tube 2 and an opening 6 provided therefor in the rear wall of the casing 4 and is terminated adjacent thereto. As shown in Figure 3, the inner end of the operating shaft 5 is rotatably received in a bearing 1 therefor mounted on a supporting plate 8 extending transversely of the casing 4 and held in spaced apart relation by posts 9 in engagement with the The bearing I beyond the end of the operating shaft 5 provides a bearing for a reduced axial stub of aswitch arm carrier member I `having a similar reduced axial stub on its other end rotatably received in a recessed rear wall thereof.

bearing stud II extending in line with the axis d of the operating shaft 'from a front plate I2 spaced apart in parallel relation to the supporting plate 8 by extensions I3 of the posts 9.

An inverted U-shaped switch operating bracket v I4 Ais perforated adjacent the free ends of each arm so that the bracket may be mounted to oscillate about the bearing II on the front `plate I2 and the operating shaft 5, The' switch operating bracket is oscillated by the movement ofthe op- .erating shaft in response to the contraction and expansion of the thermal element in response to temperature changes. To transmit;L the motion of the operating shaft 5 to the Voperating bracket, a-.disk I5 is keyed on the shaft. An actuating arm I 6, rotatably mounted on the shai t 5, of greater length than the diameter of the disk so that each end projects beyond the periphery of the disk, is provided at its lower end, with an adjustable clamping member I1 which is adapted to engage the diskto cause the arm to rotate with the disk, as -shown in detail in Figure 5: As shown in Figure 4, the upper free end of the arm IB .projects between two arms I8 and I9 exthe rear wall 'and supports the casing 4 enclosing the switch mechanism.

tending `upwardly from separate disks and 2| 26

4extensions

22 and 23 .the type No. 1,757,436, dated May 6, 1930, which closes the mounted to rotate on the shaft 5 on the side of the arm of the bracket I4 opposite the actuator arm I6. The free ends of these arms are bent rearwardly so that they will engage opposite sides of the bracket I4 and extend in the path of the free end of the actuating armv I 6. The disks 20 and 2I are each provided with angular the ends of which are bent in the direction of the front of the casing 4 and act asjanchorsv for the opposite ends of a coil spring 24 which is passed over a. grooved hub 25 rotatably mounted on the shaft 5 so as to exert tension on the arms I8 and them in engagement with the opposite sides of the bracket I4 and arm I6.

'I'he switch operated by the oscillation of the bracket I4 is a mercury tube switch, preferably of disclosed in this applicants prior Patent circuit when tilted above its transverse axis in one direction and which opens the circuit when tilted in the opposite direction. The mercury tube switch 26 is secured between clamps 21 mounted upon the upper right angular extension 2'Ia of the switch carrier arm 28 mounted upon the switch arm carrier I0. 'I'he arm 28 extends therebelow and is terminated in a right angular extension 29. An actuator stud is mounted on the arm 28 below the carrier member l0 and extends below the front plate I2 to be received in a notch 3| formed in the lower surface thereof so that the ends of the notch being engaged by the stud 30 limit the amount of oscillation imparted to the carrier arm 28. The carrier arm 28 is also provided with an oppositely extending stud 32 above the carrier member I0 which is engaged with a plate 33 mounted on the carrier member I the lower end of which is engaged by the free end of the extension 29 of the'arm 28.

The outer arm of the oscillating operating bracket I4 adjacent. its top is provided with an outstanding pin 34 which acts as a pivot for the upper end of an operating latch 35 which extends downwardly therefrom to a point adjacent the upper surface of the front plate I2 and then is provided with a hooked lower end, as shown in Figure 4. The operating latch 35 mounts an outstanding post 36 extending beyond the upper surface of the front plate I2. The hooked shaped lower end of the operating latch 35 is so formed that it includes a. l horizontal slot 31 opening therefrom and a,vertical slot 38 which provides means for slidably receiving the actuator st ud 30 upon the switch operating bracket I4. The horlzontal slot 3'1A allows the end of the latch 35 to swing, `without engagement, about the bearing post II on the front plate I2. From the structure thus described itis apparent that with the actuating arm I6 properly clamped to the disk I5.

movement imparted to the disk I5 by the shaft 5 will in turn cause the` rotation of theV bracket I4. As the bracket is caused to move from left to right the operating latch 35 is oscillated, with its lower hooked -extremity rotating around the switch actuator stud 30, extending through the slot '38, without moving the stud.

To cause movement of the 'operating latch 35 to actuate the switch 26, and to determine the temperature at which point operation of the switch occurs, two adjustable stops are provided, hereinafter described, which, when engaged by the latch post 36, serve as a fulcrum for imparting an oscillating movement to the hooked end. When the post is brought into engagement with a stop, movement thereaftt; imparted. to the I9 to normally keep y operating latch J5 will osciilate the hooked end thereoi which. through its slotted engagement with stud 30. will actuate the switch from one position to another. As shown in Figure 8. the operating shalt has rotated in. one direction to rotate the switch operating bracket i4 carrying the latch 35 with it until the post 36 thereon engages the lett hand slop. so that iurther rotation in the same direction causes the mercury switch to be tilted to the left. Whenl the switch is moved past center it continuesin its movement, by its own weight. until the stud 30 engages the end of the notch Ji in the underside or the iront plate i2 which acts as a stop to limit the travel ofthe bracket i4 and arm 2l in that direction. as shown in dot and dash line in Figure ll.

Thus a positive action is obtained in opening or closing the switch circuit. Upon oscillation ot the operating shait 5 in the opposite direct ion the movement oi the parts are reversed.

The coil spring 24. as shown in Figure 4. maintains the arms i8 and il normally in engagement. with the actuator arms IB and the bracket i4 to impart the oscillating movements oi the operai.-

ing shalt. 5 in response to temperature changes to the bracket i4 as hercinbeiorc described. when the mercury switch has been actuated and the bracket i4 and arm 2l is restrained trom further movement by the stud Jil engaging one oi the stops. should the temperature continue to change to cause the thermal coil i to expand or contract beyond that which actuated the switch. the sprlm: 24 allows further continued movementy ot the shalt l in one direction. as shown in Figure G. or

in the opposite. direction. as show-n in lFigure 7. :l

without placing undue strain upon the thermal coil or any ol the parts.

The actuating arm ii is adjnstabiv mounted upon the disk i5 secured to the shaft. 5. so that when calibrating the device compensation can be made for variations-in the relationship between the mounting holes in the thermal eoll I. As an alternative arrangement the disk i5. Figure 5. may be omitted and the arm i-G keyedA to the shaft and a suitable adjustable clamp provided upon the exterior end oi shalt 5 inr securing thereto the ouier'end oi the thermal coil no matter what its position. l

One oi the two stops [or post Si is in the iorm oi a toothed disk Il. having an annular slot 40 therein through which the post Ji projects. mounted lor rotation upon an extension oi the bearing member Ii on the iront side oi the iront plate i2. The other is an arm 4I projecting bevond the periphery 0i the disk J9 extended trom a disk mounted lor rotation about the same bearing member ii in iront ot the annular slot.- ieddisk JQ. The arm 4i terminal-s in a pointed indicator 42 and is provided with a depressed tooth 4J adapted to extend over the periphery of the toothed disk J9 and beine adapted tor engagement between two adjacent teeth thereon. The arm 4i is also provided with a bent over stop 44 extending through the annular slot 40 in the disk 3! to be in line with and act as a stop lor the post J6 on the latch 35. The disk Il is also provided with a radl'ai pointed indicator 45 adjacent the right end oi the annular sint 40. Both pointed indicators are mounted to be positioned over an annular' segment 4l secured at its'eneis upon the iront plaie i2 and provided with a calibrated temperature scale over which the pointed

indicators

42 and 45 may be adjusted,

As shown in Figures 2 and i0. the toothed disk Il ts normally restrained trom rotation by a plate or strip 4I having a notch 41 stepped at, both ends to receive a toothed disk n below its horizontal diameter and allow for rotation ofthe disk when the latter is moved out between the wider portions oi the notch but when moved forward the bottom steps oi the notch 4i enter between adjacentteethon the disk to hold it in jixed position. This strip 48 is heid with the notched portions at right angles and adjacent to the at lace oi the disk 3! by right angular extensions at cach end and perforated to be secured to the ends oi the annular scale 48 by the same means which secures the scale to the front plate i2. Provision is made to adjust the disk 39 so that the right end oi the annular slot 40 will act, as a stop for the latch stud 3i to actuate the switch at the desired temperature indicated on the scale by the pointer 45. Also provision is made to adllust the arm 4i so that its stop 4I will be engaged by thelatch stud 36 to reverse the position oi the switch atthe desired temperature indicated on the scale by the position oi the pointed indicalor 42.

The means provided tor setting the

pointers

42 and 45 at the desired temperature includes a recessed hub 40 mounting a superimposed reeessed hub 4! with the hub 4l mounted upon the portions 5U and 5h" oi the bearing member il extending tromthe iront side ol the iront plate I2, Both hubs 4I and 49 extend through an aperture 5i provided thereior in the cover l2 covering the iront oi the easing 4, as shown in Figure l. As shown in Figure 3 the inner end of the hub 4t mounts and is secured to the toothed disk 39. A coil spring 53 is mounted about the reduced portion Sii'` oi the bearing member il with one end in engagement with the shoulder 5a on the bearing member and the other in en tlagement with the shoulder within the opposite end of the recess in the hub 4l. This spring normally urges the toothed wheel t) engage the lower steps in th:` notch 41 in the strip 46". The v superimposed hub 4I is also recessed and its inner end mounts and is secured to the disk carrying the arm 4I. The outer circumference of the hub 4l is stepped to ioim a support adjacent its outer end and adjacent its inner end tor the hub 4! with a space between them for a coil spring 544 received within the recess oi the hub 49 with one end bearing upon the outer step ot the hub 4I and another against the bottom 'of the enlarged recess in the hub 4l. to be normally urging the hub 49 and arm 4i to maintain the tooth 43 on the arm 4i in engagement between ad iacent teeth on the toothed disk 38, The lower step on hub 4l acts as a stop to limit tht` outward movement of the hub 4! against the tension o't the spring 54.

B v means

oi thel hubs

44 and 49 projecting through the iront cover 52 oi the instrument casing 4. desirable adjustments oi the stops for the operating latch post 36 may be made aiter installation without removing the cwer ot the instrument casing. By depressing the hubs 4I and 49. they normally travel in unison. the toothed disk 19 is moved out oi engagement with its retaining plate 45' to allow the pointed indicator 45 to be rotated to the temperature on the seale on piate`4l desired. By pulling out hub 40 the eoil spring 54 will be compressed and allow hub 4! to slide over hub 4I to withdraw the tooth 4J on the arm 4i from engagement with the tooth wheel 3| so that the arm 4i may be rotated to the desired temperature as indicated on the scale on plate 4l. The cover ia provided with a glass covered section for viewing the calibrated plate over which the settings of the two pointers are made.

As shown in the drawings and described. 'the mercury switch IG is mounted to close its circuit when actuated upon an increase in' temperature. Such an arrangement is utilized in a device ot this character for closing a` circuit to a circulatlng fan used in conjunction with automatically controlled vand fired warm air heating systems. As in the case of such installations it may be desired to operate the fan during summer seasons for cooling and ventilatlng purposes. To utilize this improved device for that purpose this invention contemplates to provide manually operated means for moving the switch to closed position. when desired during the summer. and to lock it in that position to cause a continuous operation of the fan until released manually or, in the event of an operation of the firing mechanism, to release the lock upon a temperature :rise after which the.

device again. becomes automatic in operation in response to temperature changes.

As shown in Figures l and l2. a lock latch 55 is mounted at one end upon an operating shaft 56 rotatably mounted between the supporting plates I and i2 with one end extending beyond front platel i2 with its outer end knurled and of such length as to pass through an aperture provided therefor in the cover 52 for the casing l. 'l'he latch .5S-is so arranged that its free end may be brought into the path of travel of the actuator stud 30 and the free end is notched at 5l so that when the switch carrying arm 18 has been osclllated to open theswltch 2B the iatch- 55 may be manually rotated lo bring the notched end 5l into engagement with the actuator stud Jil and oscillate the switch carrying arm 28 in the opposite' direction to close the switch. against the force of the thermal coil tending to open the switch. Asl

a result only a part of the fitti movement normally made by the switch to full on position is utllized and the latch is locked into engagement with the stud 30. When in lliis position. the establishment. of heat which will raise the iemperature of the thermal coll to remove its torce against the locking means. the switch will automatlcaiiy more to the limit of its on position whereupon the latch lock 55 by its own weight falls tree and the device becomes automatic in operation in response to temperature changes.

When this device is employed to limit temperature conditions the position of the switch is reversed in the support clips 11.

Plates of insulating material 5B are preferably attached to the front side of the supporting plaie l for supporting binding posts 59 to which the ends of the flexible leads G0 and iii from the switch terminals arc attached. as shown in Figure 2. for connection into the controlled circuits.

What I claim is:

l. A temperature responsive device including at tiltable mercury tube switch. an operating shaft, a thermal member for operating the shalt. a tiltable bracket. means transmitting movement imiti parted to the shaft lo the bracket. a switch actualor operated by the tiltable bracket, adjustable means lor determining the tint(` oi switch operation and means upon liu` switch actuator adapted to abut said adjustable means w-hen the actuator is operated by the tiltable bracket and upon continued movement of the bracket thereafter to cause the actuator to tilt the. switch including means to limit the tilt of the switch and the movement of the bracket after operatingthe switch, and yielding means incorporated in sa'id transmitting means allowing continued movement .of the shaft beyond the limited movement of the bracket.

2. A temperature responsive device including a tiltable mercury tube switch. an operating shaft.

a coil of thermal metal for operating the shafthavlng means on one end thereof to immovably secure that end and 'means on the other end for connection upon the shalt, a tiltable bracket. an operative connection between the operating shaft and bracket including means secured upon the operating shaft. means to adjust the relation between the means secured upon the shaft and the bracket in accordance with the position. at ambient temperature. of the end o! the coil connected to the shaft, a switch actuator operated by the tiltable bracket. adjustable means for detcrmining the time of switch operation. means upon the switch actuator adapted to abtit said adjustable means when tite actuator is operated by the tiltable bracket and upon continued movement of the bracket thereafter to cause the actuator to tilt the switch.

3. The structure of claim 2 including means to limit the tilt of the switch and movement ofthe bracket after operating the switch. and yielding mcans'incorporated in said transmitting means allowing continued movement of the shaft beyond the limited movement of the bracket.

4. In a temperature responsive device having a easing. a tiltable mercury tube .switch and actuating means for tilting thc switch within the casing, the combination4 with thermally responsive means [or operating the actuating means and a calibrated temperature scale, of Aadjustable means cooperating with the actuating means for determining the temperature points of switch operation including two hubs o ne superimposed upon the other. the inner hub mounting a toothed disk having a pointer projecting beyond the periphery of the disk, retaining means to position the disk adjacent the dial and to engage the teeth 0l the disk to prevent rotation oi the disk. the outer hub mounting a pointer arm having a pawl adapted to engage the teeth on the disk. and means yielding to the depression of the hubs to release the toothed whel from its retaining means to be rotated to the desired position and byan outward pull of the outer hub to detach the pointer arm pawl from the toothed disk to rotate the pointer arm to the desired position.

5. In a temperature responsive device having a casing. a tiltable mercury tube switch and actu- 'ating means for tilting the switch within the casing. the combination with thermally responsive means for operating the actuating means and a calibrated temperature scale. of adjustable means cooperating with the actuating means lor determining the temperature points oi switch operation including two hubs, one super-imposed upon the other. the inner iutb mount ing a tooth'ed disk having a pointer projecting beyond the periphery of the disk. retaining means to position the disk adjacent the dial and to engage the teeth of the disk to prevent the rotation of the disk. the outer hub mounting u politici' ai'i'n having a pawi adapted to engage ilu.l teeth on the diskfa spring normally acting on the outer hub to maintain the pawi in engagement with the V disk teeth and yieidabie to movement of the htib theretainingmeansandyieldahlleupoumove-- mmtofthehubtofreethediskiorrotationof thehub.

0. A temperature responsive electric switch lncludingacasing,amercurytubeswltchand switch operating mechanism mounted within the casing, a .temperatureresponsive coil of thermal metal mounted exteriorly oi the casing having toopenandclosetheswitchsaidmechanismincludlng apivoted switch operating latch adapted to be actuated upon movement of the operating shaft.apostprojectmgfromthefreeend ofthe operating latch, spaced apart stops on each nde ofthelatchpostadaptedtobeengaaedbythe posti to throw the switch .from one position to another; adjustable means to position the stops upon a calibrated temperature scale to throw the switch at the desired degree oi temperature to which the temperature responsive coil is subjected.saidadjustingmeansinch1dingapost projecting through the front of the casing for manually adjusting the position of both stops.

1. The of claim 6 wherein said adjllln post is in the form oi' two hubs one superimposed upon the other, with the outer hub mounting within the casing a pointer arm having a stop. the inner hub extending therebeyond and mmmting a toothed disk having an annular alotthroughwhichthelatchpostandthestop onthepointerarmpassQtheradialedgeofthe slotactingastheotherstopforthe latchpost,a

' pointer projecting beyond the periphery of the `diskadjacenttheradialedgestop.aspring pressed pawl normally the toothed disk and a tooth struck from the pointer arm to normallybetweentheteethonsaiddishand meansyieldingtothedepressionofthehubsto releasethetoothedwheeiiromthepawltobe rotated to the desired position and by an outwardpullofthe outerhubtodetachthe pointer arm tooth from the diskwheel to rotate they pointer arm to the desired position.

8. A temperature responsive electric switch includingacasing,amercurytubeswitchand switch operating mechanism mounted within the operating shaft with the inner end of the operating shaft received in one of the bearings in the supporting plate, a U-shaped operating bracket having its free ends perforated, one to receive and oscillate about the bearing on the front plate and the other to receive and oscillate about the end of the operating shaft, a mercury tube switch supported'on theupper end of a Y carrier arm extending from a switch carrier mounted for oscillation between the adjacent perforated ends of the bracket, an operative connection between the operating shaft and an arm ,of the operating bracket, an operating latch pivotally mounted adjacent the top of the other arm of the operating bracket, and an operative connection between the operating latch and switch carrying arm whereby expansionand contraction of the thermal coil imparts oscillation to the operating shaft to operate the switch.

* 9. A temperature responsive device including a tiltable mercury tube switch, an operating shaft, a thermal member for operating the shaft,

a tiltable bracket, means transmitting movement imparted to the shaft to the bracket, a switch actuator operated by the tiltable bracket, adjustable means for determining the time of switch operation Fand means upon the switch actuator adapted to abut said adjustable means when the actuator is operated by the tiltable bracket and upon-continued movement of the bracket thereafter to cause the actuator to tilt the'switch, including a manually operated latch operable to tilt the switch to one position and hold the same in its manually tilted position against the effort ofthethermalmembertotilttheswitchtothe reverse position u'ntil in response to a temperature condition wherein the thermal member no longer opposes the actuation Iof the switch. whereupon the latch falls free', of engagement with the tiltable switch.

IRA E. McCABE.