US1704370A - Thermostat - Google Patents

Description

March 5, 1929. 1 A, M PHELAN 1,704,370

THERMOSTAT Filed Sept. 22, 192,4 '3 SheetsJ-:She t l i9 6, a@

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f' 9oli I 50" .96 lL i l "rw/J O March 5, 1929.

L. A. M. PHELAN 1,704,370

' THERMOSTAT Filed Sept. 22, 1924 5 Sheets-Sheet 2 March 5, 1929. L. A. M. PHELAN THERMOSTAT Filed Sept. 22, 1924 5 Sheets-Sheet 3 Panta Mar. 5,1929. ,s 1,704,370

UNITED STATES PATENT OFFICE'.

LOUIS A. PHELAN, OF IBELOIT, WISCONSIN, ASSIGNOR TO AB\SOLIITE CON-TAC-TOR CORPORATION, OF BELOIT, WISCONSIN, A CORPORATION K015' ILLINOIS.

l x THERMOSTAT. p

Application led September 22, 1924; Serial No. 739,056.

My invention relates to automatically opment, is provided for the mercury contactor, erated electric switches and more particuallowing the contactor to be tiltably carried larly tofthose having enclosed contacts so that it is sensitive -to the slightest movewhich make and break the circuit andl which ment by the thermostat.

are capable of handlingsubstantial quan- A further object of my Iinvention is to 60 tities of current at commercial voltages.` provide the resilient supporting means for While I shall describe my invention asl the lmercury contactor in the form of cur- =having particular application to` a type of rent conductors coextensive withthe leadswitch provide with enclosed contacts, itl iii-wires whereby a`dual function is providwill nevertheless ybe understood that any ed: viz, that of absorbing the kinetic energy 65 type of switch may be used, which is autoof the movable body of mercury within the matic in operation and may be actuated by\ contactor, which places the opposite side of an actuating force imparted by La device this supporting means under tension to provided for the purpose, notwithstanding rassist in the return of the contactor to its 16 that the former type of switchmay be prefnormal position, and secondly, that of carry- 70V l erable on account of its durability and siming the electric current to the lead-in-wires plicity of design. which eliminates the usual wires heretofore The present invention, however, refers employed. more particularly to a thermostatically op- A still further object of my invention is 20 erated switch which comprises a heat reto provide an improved form of mounting 75 sponsive element or thermostat that profor the thermostatic or heat responsive elevides .an actuating force for the electric ment whereby it will be thermally insulated switching mechanism" for opening and closfrom its support, and so positioned that the ing the electric -circuit as the thermostat. natural flow of air currents will contact expands andcontracts by reason of tempera.- with its maximum surface.

. ture changes that may inliuence it. In accomplishing these and other objects The switch, which I employ, is preferand advantages of my invention, Iam able I ably of the tiltable mercury contactor type to provide an exceedingly simple and comwherein -thevco-operating contact members pact arrangement of the parts in a device or electrodes between which thel circuit is Which is durable, reliable and eiiicient. 85

made and broken, are fixedin position and -When controlling motor circuits, I have are adapted to be bridged by a conducting found it unnecessary to employ relays or body, such as mercury, that is moved to and like devices,` as the switching 'mechanism fro by an actuating thermostat at the eX- which I use has a large current carrying ca- 5 pense of very little energy, such as may be pacity and is capable of quick and accurate 9o .available when a temperature ,change of a operation by the expenditure of very little few degrees only, or even a degree, may energy. f occur. The co-o'perating contact members In the drawings: v of my f, switching device are spaced a suit- Figure 1 is a front elevational view of a 405able distance from one another to preclude device embodying my invention withlfthe 95 premature electric discharges between cover'omitted so that the various operating them, and they are completely enclosed in parts of the structure will be more clearly a sealed container, thereby insuring them illustrated; J against corrosion, contamination and dcte- Fig. 2 is aside elevationalview thereof i rioration. with the cover illustrated in section showing 100 An object of my invention resides in the 4the manner of mounting the device upon a provision of an improved form of thermowall in thermally insulated relation;

- y statically operated switch of the tiltable Fig. 3 is a perspective view of the mercury mercury contactor type, wherein novel means contactor and the mounting provided thereare provided for resiliently supporting the for; 105

mercury' contactor and for absorbing the Fig. 4 is a section taken on line' 4-4of 1 kinetic energy of the movable, body of mer- Fig. 1, illustrating the means for adjusting c ury contained in the contactor uponoperathe tilting 4position of the mercury contion of the. switch. A pivotal mounting tactor.; K

which is connected `to the tliermostatic ele- Fig. 5 is a horizontal sectional view illus- 110 trating the knife blade engagement of the laforesaid lmeans illustrated in' Fig. 4 withl ing a modified form of my inventionzwhich is provided with the thermostatic element in vertical position; Y I

Fig. 10 is aside elevational view thereof; Fig. 11 isa front view of another modified form of my invention; and

Fig. 12 is a view of 'the same device looking from the rear thereof.-

The device illustrated in Fignres 1 and 2 preferably comprises a mounting base 1 of bakelite, or other suitable insulationx material, to which is secured a bracket 2 by means of screws 3 entering from the rear of the base l and having their heads seated within a recess 4 inthe rear face of this base. Bracket 2 is provided with a for.- Wardly extending portion, 5 having a slotv 6 cut therein along 4the front edge. A thermostatic element L7 is adapted to be suption or expansion of .the bellows 7 may be i transmitted, to allow the upper end ofthe actuating member to readily flex for operating a mercury contactor .25, suitably -supported at the upperend of insulating base 1.

Mercury contactor 25, in this instance,

comprises. a sealed container 26, preferably a glass` tube, in which cooperating electrodes 27 and 28 are sealed. The container ported upon insulating base 1. Thermo-" static element 7 is of the expansible and contractible bellows type, the interior of which may be provided with a highly volatile fluidwhich renders the bellows sensitive to the slightest temperature change. In order that the operation of the bellows will be eiiicient and accurateand will notfbe influenced by the temperature of the adjacent parts ofl the device, I provide a thermally insulated support which prevents the cbnduction of heat to the bellows 7. This thermally insulated support, as illustrated in the Figure 6, comprises a projecting shank 10 at the right-hand end ofthe bellows and a heat -insulated collar 11 adapted to' seat in slot 6 of bracket 2. Nuts 12 on each side of the collar 11 serve to hold the shank 10 seated in the 'slot 6 of bracket 2. The left-hand side of the bellows 7 terminates in a stud 13 adapted to seat in a recess 14 provided in a bearingl 15. This bearing 15 ff is furnished with a point contact with one end of a screw 16 projecting from an actuating member 17.

Actuatingmember 17 is vertically positioned and is adapted to be furnished with a lleaf/spring mounting 18 at its lower end.

As illustrated injFigure'7, which is a bottom plan viewl of this leaf spring mounting, the actuating member 17 is provided with a horimercury 29, aswell as -an :inert gas. The container 26 is of tubular form having its longitudinal axisplaced approximately horizontal. The electrodes or'contact members 27 and 28 are made ofpure metal and are disposed on one side of the axis of rotation of the mounting for the mercury contactor. A tiltable mounting is provided for the mercury contactor, which allows mercury 29 to ride on a lower annular surface of container-26, and, when tilted to the left of Figure 1, it serves to establish an electric circuit betwgen the electrodes 27 and 28. When the contactor 25 Ais tilted in the direction illustrated in Figure 1, .the mercury 29 flows tothe `other end of the conf ytainer 26 and thereby opens the electric circuit between the cooperating contact members or electrodes 27 and 28. Electrode 27 is connected in electrical circuit through a leading-in-wire 30, which is embodied in the glass shank 31, thereby providing a substantial support for the leading-in wire 30.

bedded in a glass shank 33. Thus it will be seen that the electrodes 27 and 28 are -23 is evacuated .and contains a body of fixed and stationary with respect to each ing a portion 37 which is aperturedv at its lower end as indicated at 38. An annular clamping ring 39 securely grips the mercury contactor 25 at a point substantially midway of its ends. The clamp 39 is brought tightly against the glass container 26 by means of a screw 40 and a cooperating nut 41. One of the lower ends, desig-r nated 4:2,k of clamp 39\forms a downwardly i projecting apertured extension, while the vother end 43 of said clamp 39 is adapted to have fixed thereto one end of a rod 44. The opposite end of this rod 44 is pivoted in the lower apertured end 38 of the portion 37 of bracket 34. From the description thus far, it will be seen that I provide` a pivotal mounting for the mercury contactor 25, which is located substantially at a point between the ends of the contactor. The arrangement reduces frietional losses to a minimum because friction at th/e pivot point of contactor 25 is practically negligible. Apertured extension 42 of clamp 89 is 4adapted to connect to the rupper'end of the actuating member 17 by means of a rod 45. Actuating member 17 has yits upper endV 46 also apertured which permits rod 45 to be accurately adjusted with respect to the actuating arm and position of the contactor 25, to compensate,f for any mechanical or manufacturing inaccuracies.

Tol provide a balanced support for the mercury contactor 25, I provide means for resiliently supporting the contactor at its ends. In addition to accomplishing this purpose, said means further functionsto absorb the kinetic energy of the movable body of mercury 29 in the container 26 when the switch is actuated. This means comprises a pair of leaf spring members 48 and 49, best illustrated in Fig. 3. Each leaf springv is provided with an extension 50, which is adapted to connect with the terminals 51 of the electric circuit. The leaf spring extends upwardly and then outwardly, re sulting in forwardly projecting arms 52. The end of each arm 52 is apertured for the purpose of receiving, in fixed relation, the projecting tips of the lead-in wires 30 and 32. The spring members 48 'and 49 are in electrical conducting relation between the lead-in wires 30 and 32 and the terminals 51'l of the circuit. This arrangement elim` inates flexible leads and further eliminates the influence which tension in flexible leads would have on the movement of the contactor 24 when operated. Furthermore, these resilient members tend to restore the contactor to normal position when tilted irrespective of whether normal position is in closed circuit position or open circuit position. 1

I provide means for adjusting vthe tiltable position of the contactor 25 in order to obtain a proper setting or .adjustment of the bellows 7, so that it will be adaptedto operate the contactor at a desired temperature change. This means comprises a hori Zontal tension spring 55 having its axis substantially parallel to the axis of the bellows 7 and adjustable by a knurledthumb screw 56 which is journaled in a portion 57 of bracket 2. Spring 55 tends to place a tension on the actuating member 17, and, due

to the fact that its axis isparallel to that -of the bellows, this tension will be maincarried by\a second screw 58. As illustrated v in Figure 5, an aperture 59 of a diameter greater than the diameter of screw 58 is furnished in actuating member 17, and through this aperture 59 screw 58 is adapted to project, the screw being held out of contact with the periphery of the aperture. At the outer end, a `member 60, through which screw 58 passes, furnishes a knife blade contact between ythe actuating member and the screw 58. The tension on t-he actuating member 17 may be varied by turning the knurled screw 58 in either direction. It will be noted in Fig. 4 that the actuating member 17 has a lateral extension 61 ex-v tendingn between spaced parallel lugs 62. Lateral extension 61 of the actuating member 17 has, therefore, limited movement between these spaced parallel lugss62. vWhen reaching the end of its movement, the projection 61 still' allows further tension' to be applied to the actuating member 17. Mini-l mum frictional losses are obtained where the tension spring 55 connects to the actuating member 17, and consequently, a finer adjustment of the position of contactor 25 at its pivotal mounting may be obtained. An indicator plate 68 may be secured` to the portion 57 of bracket 2, as indicated at 64.y Qne end of tension spring 55 is soldered or otherwise secured to a collar 65, from which a member 66 projects. An indicator arm 67 is pivoted at 68 to indicator plate/63. The upper portion of indicator arm 67 em# braces the periphery of indicator plate 63 along which temperature calibrations are provided for indicating the ,temperature at which the bellows'may be set to operate the switch.;

very fine and accuratetemperature setting may be obtained by having the fulcrum point of actuating arm 17 substantially at its lower end. By having its point of conj \tact with the bellows substantially adjacent.

to this fulcrum, the actuating arm 17 multiplies the motion of the bellows in a large ratio, and consequently, secures operation of the contactor 25 with a very slight motion of the bellows.v The thermally insulated support for the bellows secures maximum efficiency in the operation of the latter, and the temperature of the surrounding parts will have practically no effect thereon.

In Figure 8,'I have illustrated a cover 70 adapted to be placed over the front of the device and suitably secured to the insulating mounting base 1. A plurality of elon gated ventilation openings 71 are provided in the cover 7 0 on the under side, and at the l45 currentsl of air the bellows presents a maxia lug 85 fixed to t e casing 87, .Bracket 84 l `mum surface. The bellows-7 1s, therefore, is guided in its movement by a screw 88 upper end of the front face, a second set and moreover, the disposition of the bellows' recess 90 similar to the recess 4\in the lower f so that a maximum surface thereof is exposed to the air currents within the cover permits the device to be very sensitive to any change of temperature in the room.

` In Figure 2, a novel form of wall mounting for the insulating base 1 is illustrated. A

end is provided in the upper end of the in,- sulatingbase 1. Thermal insulating material 91, such as felt, or the like, is adapted to be inserted inrecess 90. Attached to the wall at end of a coil spring 55, as yindicated at 80.

Actuating arm 17 then extends downwardly at 7 6 to provide a leaf spring mounting 77, which is similar to the mounting 18. The upper end of actuating arm 17 interconnects with contacter 25, which is provided with a mounting substantially the same as in the form previously prescribed.y While I have not shown an indicator'plate in connection with this embodiment, it is to be understood that the same Imay be provided and` connected to the tension spring inj any suitable/manner, so that the movement ofthe knurled thumb screw 56` will adjust the tilting position of the contactoi; 25 with respect to the bellows 7.

In Figures 11 and 12, I have illustrateda device embodying several of the essential features of my inventionwhich is, however,

.proper connecting-of the wiring may be )a thermostatic element.

this point is anv outlet box 92,L in AWhich operated by -a pressure element instead of l By referring to made. Wires 93' leading from the front side Figures 11 and 12, it Awill be noted that one of insulating base 1 at the terminals 50 are end of the Bourdon pressure gauge 79 is connectedy at 94 to circuit wires 95 leading connected to a, nipple 8Oa while the opposite upwardly through the COIldut 96- This 211'? end has a rod 81 fixed thereto. A link 82 rangement serves to thermally insulate thev ispivotally connected at 83 to a bracket insulating base 1 from the outlet box 92 84, In this device, which is usually sunk in the wall and subject otally mounted and resiliently supported at to currents of air therein, which currents of its ends, the same as was previously dea1 r are generally of varied temperatures and' scribed for the embodiment illustrated in dlferent from fthe room temperature, and Figures Lto 8 inclusive. Link 82 connects are apt to affect the operation of a sensitive with the depending arm 42 of the clamping thermostat. The pad of felt 91 covers the ring .39 carrying the contacter 25. Upon lportion of the base 1 exposed to the outlet movement of the Bourdon gauge 79, the rod box 92 and preventsconduction of heat to' or 81 with its right-angular projections 83 will from the base 1, thereby thermally insulatvtend to engage the under side of link 82 for ing it from all temperature effects as the retilting the mercury switch to open and close sult of its contact with the wall. It is there- Ythe circuit.

by impossible for the temperature controlled j In order to adjust or set the, device to Abellows 7 to expand or contract except by operate at a predetermined pressure, aslotthe temperature effects of the currents of ted bracket 84, to which the link 82 is pivvshanksof these screws which would otherair circulated through the cover, to which oted, is fastened b means of a screw 86 to sensitive and dependable, and exceedingly riding in its slot and entering the lug 85. accurate in its operation of the contactor' Casing 87, however, is provided with an 25, the latter being capable of tilting at opening\89 into which a tool may be inserted the slightest movement ofy` the bellows 7. for adjusting screw 86. When it is desired Insulating base lmay be provided with for the device to operate at a desired presa plurality of elongated slots99 which are sure, the tilting position of contactor 25 is adapted to receive screws 100 for mountingv varied, this in turn changing the position the base to the` wall. Screws 100 pass of the arm 82 with ,respect to`the right through the felt 91, but the felt serves to Langular projection 83, so that'a greater or a cover the slots, and due to.' their elongation smaller movement ofthe link 81 `will be re- (which permits adjustment of the screws) quired, it depending on the pressure at the felt prevents an opening adjacent the i-which 'the device isfto operate. l

The mercury contactor 25, which I have l disclosed herein, may be of any type, if so wise appear.

0n-Figures 9 and 10, I have illustrated desired. However, as I have disclosed it, it the device provided with the bellows 7 and is of the type of contactor more particularly coil'spring 55 disposed vertically. The ac-X described and' claimed in my `copending aptuating member 17 is provided with a lateral plication, vSerial Number 530,243, led v contactor 25 is also piv- A' embodiments of my invention, it is to be uni derstood that many modifications may be madetherein without departing from the scope and spirit of the appended claims, and

, furthermore I desire thatonly such limita- .rtions shall be imposed as are specifically pointed out in the claims and such as are required by the prior art.

I claim:

1. An electricswitch comprising a tiltable mercury contactor, a bracket upon which said contactor is pivotally mounted, and a spring member .having one end fixe and stationary and resiliently supporting said' contactor at an electrode lead-in wire for absorbing the kinetic energy of the movable body of mercury contained in said contactor.

2. An electric switch comprising a tiltable mercury contactor, a bracket upon which said contactor is pivotall kmounted, and leaf-spring members "having one of their ends gfixed and stationary and their other ends resiliently .supporting said contactor at the electrode leadg-in wires for absorbing the kinetic energyof the movable body of mercury contained in said contactor.

3. An electric switch comprising a tiltable mercury contactor, a bracketr upon which fsaid contactor is pivotally Jmounted, and leaf-spring members having one of their ends xed and stationary and their other ends resiliently` supporting said contactor and servingL as current conductors to said contactor. f Y

4. An electric switch comprising a tiltably mounted A contactor,A a mounting base therefor, spring members secured at one of their ends to said mounting base and attached at the other of their ends-to the electrodes of said contactor thereby permitting said contactor to be tilted.

l 5. An electric switch comprising a mounting base, a mercury contactor pivotally mounted` thereupon, and spaced leaf-spring members severally attached at one of their ends to said mounting base and secured at the` other of their ends to the electrode lead-in kwires of said contactor, said leafspring members serving'as conductors for said contactor and as shock-absorbing means for abs/orbin the kinetic energy of the `movable body o mercury in said contactor.

6. An electric switch comprising a tiltable mercury contactor, a bracket for pivotally mounting said contactor, and leaf-spring members disposed on both sides of said bracket and having one of ,their ends attaohed to the electrode lead-in wires of said contactor and the other of their ends fixed and stationary.

7 An electric switch comprising a tiltable` mercury contactor, a member upon which said contactor is pivotally mounted, and resilient means disposed on each side of said mounting member and having `one of their ends connected to the electrode lead-in wires of said contactor and the other of their ends fixed and stationary, lsaid resilient means serving as current conductors and as shck-absorbingmeans for said contactor.

8; Anelectric switch comprising a tiltable mercury contactor, a bracket for pivotally mounting said contactor adjacent to its center, and leaf-spring members vdisposed on both sides of said bracket and having one' of their ends engaging said contactor adjacent to its ends and the other ends of said leaf-spring members being `fixed and stationary.

9. An electric switch comprising a pivotally mounted mercury contactor, and L- shaped leaf-spring members resiliently supporting said contactor upon its pivotal mounting and serving as current conductors to the electrodes of said contactor, said 11. An electric switch comprising amount- .ing base, a bracket, a mercury contactor pivotally mounted on said bracket, space d leaf-spring members having one of the1r ends connected to the electrodes of said contactor and the other of their ends secured to said base member for resiliently supporting said mercury contactor, means for adjusting the tiltable position of said contactor, and eXpansible and contractible means for tilting said contactor upon said bracket.

12. An electric switch comprising a mounting base, and a mercury contactor pivotally mounted thereupon, resilient supporting mea'ns for balancing said contactor about its pivoted mounting and serving as current-conductors to said contactor, and expansible and contractible means for tilting said contactor about its pivot, said resilient supporting means being stationary and fixed sto said mounting base and serving to absorb the kineticv energy of the movable body of mercury contained in said contactor.

13. 'An electric switch comprising a mounting base, a mercury contactor pivoted thereupon, L-shaped. leaf-spring members and balancing said contactor about Said supporting said contactor about its pivot at n its leading-in wires upon one of their ends,

electric terminals connected to the other ends of said leaf-spring members, and means for tilting said contactor Jabout its pivotal mounting, said leaf-spring members being stationary and supported upon said mounting base and serving to absorb. the kinetic energy of the movable bodyof mercury contained in said contactor.

14. An electric switch comprising a mounting base, .a mercury contactor, a pivotal mounting ,for said contactor, L-shaped leaf-spring members .supporting said contactor at its leading-in wires upon one of their ends `and balancing said contactor upon y said pivotal mounting, electric terminals connected tol the other ends of said leafspring members,.means for tilting said contactor about its pivotal mounting, said leafenergy of the movable body of mercury contained in said contactor, and means for varying the position of said contactor about its pivot.

15. An` electric switch comprising a mounting base,` a mercury contactor, a

pivotal mounting for' said contactor, L*-

shaped leaf-spring members supporting said contactor uponone of their ends7 to balance said contactor upon said pivotal mounting and the other ends of said leaf-spring members being secured to said mounting base, rheat responsive means for tilting said contactor about its pivtol mounting, said leafspring members serving to absorb the kinetic energy of the movable body of mercury contained in said contactor, and means for varying the position of said contactor about its pivot.

` 16. A balanced mounting for a mercury contactor having a centrally located pivot comprising a clamping member' secured at a substantially central point on said contactor, a bracket for carrying said 'clamping member, and resilient members adapted to be attached to the ends ofv said contactor and tending to return the contactor to normal position when tilted.

17. A balanced mounting for a mercury contactor comprising means providing d,a centrally located pivot for the contactor,v in combination with resilient members connected directly to the leading-in Wires," ofy said contactor adjacent to both of itsends and tending to balance the contactor about said pivot while tilted, said resilient members serving as current conductors to said leading-in wires. f

18. An electric switchicomprising a pivotally mounted mercury contactor, a base for Said pivotal mounting, resilient means con-V pivotal mounting, said resilient means being attached to said base, a thernally insulate lheat responsive device on said base, and in- 1 n a said plvotal mounting, reslllent means connected adjacent to the ends of said contactor land balancing said contactor about said pivotalmounting, said resilient means beingv attached to said base, a heat responsive means for actuating said contactor, means for horizontally mounting said heat responsive device on said base in thermally in sulated relation, and meansfor interconnecting said contactorand said heat responsive device, said resilient means serving asi Vcurrent conductors to electrodes in j/said contactor. l'

20. electric switch comprisingY a tiltable mercury contactor, a pivotal mounting therefor, a base for said pivotal mounting,

resilient electrical conductors connected to` base, a heat responsive device for actuating said, contactor, means for horizontally mounting said heat responsive device on said base in thermally insulated relation, a vertical actuating arm having its fulcrum in close proximity to the point of contact with said heat responsive device for multiplying 'the movement of said heat responsive device, and adjustable means interconnecting said actuating arm with said contactor for transmitting thereto the adjustably multiplied movement of said heat responsive device.

21. AnA electric switch comprising a tiltable mercur contactor, 1a pivotal mounting therefor, a ase for said pivotal mounting,

resilient electrical conductors connected to thelleading-in wires of said contactor adja- 4centto. the ends thereof, said electrical con-- ductorsY tending to balance said contactor' about said pivotal mounting ,and having their corresponding ends attachgd to saidj base, a heat responsive device on said base for actuating said contactor, an actuating arm for transmitting the movement of said heat responsive device to said mercury contactor, said actuating arm being disposed at lright angles to the axesofsaid contactor and said heat responsive dev1ce, and"adjust i ablemeans for varying the degree of movement of said contactor in response to said heat responsive means. f I

.22. An electric switch comprising a tiltable mercury contactor, a pivotal mounting therefor, a base for said pivotal mounting,

tactor, a heat responsive device mounted on said base, an actuating arm interconnecting said' contactor and heat responsive device for transmitting the motion of the latter toithe former, said actuating arm being mounted for, movement substantially in the same direction of movement as `said heat responsive device, and adjustable means'for varying the degree of movement of said contactor in response to said heat responsive means. l

' 23. An electric switch comprising a tiltrable mercury contactor, a pivotal mounting therefor, a base for said pivotalmounting, resilient electrical conductors connected to the leading-in wires of said contactor adjacent to the' ends thereof, said electrical conductors tending to balance said contactor,1

about said vpivotal mounting and having their corresponding ends attached to said base, a heat responsive device mounted on said base in,l thermally insulated relation, an actuating arm for transmitting the motion of said heat responsive device to said contactor, said thermally insulated mounting comprising a bracket, a shank 'at one end of said heat responsivedevi'ce adapted to seat in said bracket, thermal insulating material between said shank and said bracket, and a single sharp point contact between the opposite end of said heat responsive device and said actuating arm whereby the heat` flow between said arm and said heat responsive device will be minimized.

24. An electric switch comprising a tiltable mercury contactor, a mounting base therefor, Ya heat responsive device mount; ed on said base in thermally insulated relation, an actuating arm fortransmitting the motion of said heat res onsive device to said contactor, said thermal. y insulated mounting comprising a bracket, a shank at one end of said heat responsive device adapted to seat in said bracket thermal insulating material between said-shank 'and said bracket, single point contact member aflixed to the opposite end of said heat responsive device and engaging said actuating arm, and means including an adjusting screw carried by said actuating arm for engaging said single point contact member.

v25. An electric switch comprising a tiltable mercury contactor through which an external electric circuit is controlled, a

mounting base for said contactor, an expansible and contractible-bellows serving as a heat responsive device for actuating said contactor, an actuating armv engageable by the movable end of said bellows for transmitting the motion of said bellows to said contactor, and an adjustable element interfposed between said actuating arm and the movable end of said bellows for permitting initial calibration of the latter when mount- -ed on said base. i

26. An electric switchl comprising a tiltable mercury contactor through which an 'external electric circuit is controlled, a

mounting base for said contactor, an eXpanvsible andicontractible bellows serving as a heat responsive device for actuating said contactor,van actuating arm enga eableby the movable end of said'bellows or transmitting the motion of said bellows to said contactor, and an adjustable element interposed between said actuating arm andjthe movable end of said bellows for permitting initial calibration of the latter when mounted on said base, said element providing a point contact for the movable end of said bellows for minimizing friction and heat conduction thereat.

27. An electric Aswitch comprising a tiltable mercury contactor, amounting base therefor, an expansible and contractible element horizontallydisposed thereon, an actuating arm for connecting said contactor and .said element in operative relation, a casing housing .the aforesaid elements, and means for varying the tilting position of said contactor whereby said element may be adjusted so that its movement to operate said contactor maj be predetermined, said means acting paral el to the aXis of said element and being exteriorlyaccessible of said casing.

28. An electric switch comprising a tiltable mercury contactor, a mounting base therefor, an expansible and contractible element horizontally disposed thereon, an actuating arm for connecting said contactor and said element inoperative relation, a tension spring acting in a direction parallel to .the laxis of saidf element for varying the tilting position of said contactor, a casing housing the aforesaideleinents, and means eXteriorly accessible of said casing foradjusting saidj tension spring.

l 29. An electric switch comprising a tiltable mercury contactor, a mounting base therefor, an expansible and contractible elehment disposed thereon,y an actuating arm adapted toconnect said contactor and said element in operative relation and spring means associated with said actuating arm at .s

a point intermediate said contactor and ,element for varying the tilting'position of said contactor, said spring means includingY atension spring provided with a. knife blade engageinent with -said actuating arm and an adjusting means for varying the tension of said spring against said actuating arm.

30.y An electric switch comprisingamounting base, a heat responsive bellows v'located at the lowermost. portion thereof and having its axis placed horizontally, a vertically'arranged lever pivotally mounted adjacent. to said bellows and extending upwardly there'- from, a tiltable electric contactor pivotally vmounted adjacent to the upper end ofsid leverand near'the upper portion of said mounting base, and means for connecting i .saldf lever and said contactor whereby movements of the said bellows maybe imparted to tilt said contactor, said contactor comprisin a container, electrodes sealed therein and a of mercury adapted to control an external electric circuit through said elec'- Vtrodes when said contactoris tilted.

, 31. An electric switch comprisingamountingf base, a horizontally disposed heat Yresponsive yelement located at the lowermost portion thereof, an electric tiltable contactor .located on said base above said heat responsive element, means for connecting said contactor and said element in operative relation, and a container for said heat responsive element having vents therein whereby the maximum surface of heat responsive elements is presented `to the natural flow of air currents that influence said heat/responsive elements,` said contactor comprising a container, electrodes sealed therein and a body of mercury adapted to control an external electric circuit through saidelectrodes when said contactor is tilted.

32. An electric switch comprising a tiltable mercury contactor, a mounting base therefor; a'fbellows element located at the .lower portion-of said base and having its for said contactor` including an apertured'depending arm, an expansible and contractible ellows serving as a heat responsive device, an actuating arm between said contactor and said bellows, the end of said actuating arm adjacent to' said contactor' having lone or; more apertures provided therein, and an interconnecting member between the apertured end ofsaid actuating arm and said apertured pyro-1,979 I depending arm permitting accurate adjustment of the parts tol compensate for inaccuracies in the manufacture thereof.

'341. An electric switch comprising a tiltable mercury contactor, a mounting ,base

therefor, means for pivoting said contactor upon said base, and resllient conductors havmg one of their ends attached to said base and their other ends lattached to the leading-r "in'wires" of said contactor atthe end'por-tions thereof for balancing said contactor upon its pivoting means.

35. An electric switch comprising a tiltable contactor, a mounting base, pivotal` means engaging said contactor intermediate its ends, and spring members constituting leading-in-wires for said contactor and being connected to the end portions of said contact-or for balancing the same upon its pivotal means.,

36. An electric switch-.comprising a co-ntactor, a mounting base therefor, means for pivoting said contactor adjacent to its center 4 upon said base, spring means vconstituting leading-in wires to Isaid cqntactor for balancing said contactor vin normal position upon its pivoting means, and actuating 'means for tilting said contactor in\ opposition tothe force exerted thereupon bysaid spring means.

37. An electric switch comprising a contactor, a mounting base therefor, means for pivoting said K contactor upon said base,

spring means constitutingleading-in wires to said contactor for balancing said contactor in normal position upon. its pivoting means, and heat responsivepmeans for tilting saidrontactor upon its pivoting means in opposition to said spring means.

38. An electric switch comprising a tiltable mercury contactor, a mounting base therefor, resilient supporting means providing ycurrent conductors for said contactor, and a pressure element fortilting said contactor about its pivot, said resilient supporting means serving to absorb the-kinetic energy of the movable body of 'mercury contained in said contactor.

39. An electrictswitch comprising a tilt;

\. able mercury contactor, resilient supporting means for said contactor adapted to servel as current conductors therefor and tending to minimize the energy required Ato vtilt said contactor as well asbalance the same when tilted, a pressure element for tilting said-con- A tactor about its pivotvfor opening and closing the circuit, and an adjustable connection between said contactor and said pressure element for predetermining the effectiveoperating pressure of said pressure element.

In witness whereof, I have hereunto Vsubscribed my name. 4

' LOUIS A. M. PI-IELAN.

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