US2086755A - Control device - Google Patents

Description

July 13, 1937. c. J. WERNER 2,086,755

CONTROL DEV I CE Original Filed Aug. 22, 1954 4 Sheets-Sheet 1 C. J. WERNER CONTROL DEVICE July 13, 1937.

Original Filed Aug. 22, 1934, 4 Sheets-Sheet 2 INVENTOR m July 13, 1937., c. J. WERNER V2,086,755

CONTROL DEVICE Original Filed Aug. 22, 1934 4 Sheets-Sheet 3 4.52 @2g/@ f 27@ Y 2% v E72 270 m 388 266 24 384 268 382 386 Mawr/a 3/4 273 L l l/l/YsaLHr/O/Y 304Z 374 Flg.g//vsz/Hr/g8/;3%Zg2 4M; 302

U 384 370 @l 230 284 76 3% j`Z/q4. 2%

/rvsumnO/V I 3453j 272 ily' M f 32 Y se@ @am 3653/270260 #Kw4/9770 N! 408 @'14 4 406 INVENTOR Mu WMM E /ff f ATTORNEW/ July 13, 1937. c. J. WERNER 2,086,755

l CONTROL DEVICE Original Filed Aug. 22, 1934 4 Sheets-Sheet 4 460 /4-3t4 455 446 44 4 4? 443 452 w@ 462 M .440

lNVENTOR JQ (5 ATTORNEW Patented July 13, 1937 'UNITED STATES PATENT OFFICE CONTRL DEVICE Application August 22, 1934, Serial No. 740,961 Renewed September 2;, 1936 15 Claims.

This invention relates to a control device, and more particularly to controlling an electrical circuit in response to a control device for a thermalresponsivel device.

An object of this invention is to provide a thermal-responsive switch that is inexpensive to i build, durable, and efiicient in operation.

Another object of this invention is to provide a thermal-responsive switch having more than one set of contactsL controlled by a thermal-responsive element, so that a plurality of circuits are controlled in a predetermined sequence by the thermal-responsive element. ASuch a switch is particularly adapted, for example, to the control of the starting and running circuits of an electic motor and to ,providing overload protection for the motor. In the disclosed embodiment of the invention, this object is accomplished and such a switch provided in one aspect of the invention by the combination incorporating a support, Stationary contacts secured to the support, movable contacts adapted to engage the stationary'contacts and carried by separately electrically insulated pivotally 4molinted d contact carrying members, a thermal responsive actuatingelement anchored at one end and operatively connected to the contact carrying members through an intermediate memberin such a way that the contact carrying members are actuated at different times, and springs each anchored at one end and having their other ends connected to the contact carrying members.

Another object of this invention is to provide a switch for controlling an electrical circuit, which `switch ris actuated by a thermal-responsive element and has means, for effecting quick make and break of the contacts. An example of a use to which such a switch is particularly adapted is, that of controlling the starting and running circuits of an electric motor. In the disclosed embodiment, one aspect ofthe invention is provided by a combination incorporating a support, a stationary contact secured tothe support,'a movable contact adapted to engage the stationary contact, which movable contact is mounted on a pivotally supported contact carrying member and insulated from the stationary contact, a spring anchored at one end and havingv its other end connected to the contact carrying member, a thermal responsive element yanchored at one end near the anchored end of the spring, said thermal responsive element and spring being substantially parallel to each other, the pivotal mounting for the contact 'carrying member being nearer the end of the spring that is (Cl. G-113) fastened thereto than to the other end of the' spring, and said spring exerting a continuous: force against the movement of the thermal responsive element in one direction, the magnitude of which force diminishes after movement is started and continues to diminish until after ther contacts are broken.

Further objects and advantages of the present invention will be 'appar-ent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

in the drawings:

Fig. l-s an elevation of a switch embodying a preferred form of the present invention.

Fig. 2 is a perspective view of the back of the switch shown in Fig. 1.

Fig. 3 is a sectional View of the switch shown in Fig. 1 with the switch contacts closed, and is taken substantially on the line 3--3 and in the direction of the arrows, as indicated in Fig. 1.

Fig. 4 is a sectional view of the switch shownA in Fig. 1, with the switch contacts open, and istaken substantially o-n the line 3-3 and in the direction of the arrows, as indicated in Fig. 1.

Fig. 5 is a perspective view of a link utilized in a preferred form of the switch shown in Figs. 1, 2, 3 and 4.

Figs. 6 and 7 are perspective views of a modied form of the switch combining two switches 4similar to that shown in Figs. l, 2, 3 and 4 into a single unit.

Fig. 8 is a fragmentary view of a portion oi' the switch shownI in Figs. 6 and 7, with the contacts in the open position.

Fig. 9 is a perspective view of a preferred form of switch having a plurality of contacts actuated by a single thermal-responsive element.

Fig. 10 is an end View of the switch shown in Fig. 9.

Figs. 1l, 12, 13 and 14 are fragmentary views showing positions of the contacts in the oper-- ation of the switch shown in Figs. 9 and 1 0. l

Fig. 15 is a preferred form of motor control circuit embodying the switch such as that shown in Figs. 9 and 10.

Figs. 16 and 17 are modified forms of motor control circuits embodying the present invention.

With particular reference to Figs. 1 lto 4 inclusive, a support or housing I0 is preferably made of insulating material such as molded phenol fiber and has-a base or back portion l2 and side walls Ill and I6. In the particular form illustrated,A the Switch is particularly adapted to -be utilized for the control of an electric motor,

and altho it is not at all limited to that use, the side wall i4 is shown as curved, so that the switch ilts inside of the motor housing. An opening i8 is provided in the support for the'accommodation of suitable mounting means.

' Support members 20 and 22 are secured to the back I2 of the support or housing i0, preferably by' being molded into the insulating material. The support members 20 and 22 have notches such as 24 therein. A contact carrying member 26 has knife edges such as 28 that cooperate with the notches 24 to'provide a pivotal mounting for the contact carrying member. The contact carrying member L26 has an arm portion 30, near the endI of which arm portion a contact 32 is mounted.

The contact 32 has head portions 34 and 36 and a stern portion 38, which stem portion is slidably mounted in an opening, not shown, in the arm portion 30. A spring 4|)l is interposed between the arm portion 30 and the head portion 34 to resiliently urge the head portion 34 away from the arm portion 30. The spring 42 is anchored at one end, preferably by clamping that end between suitable spacers 44 and 46 on a screw 48, which screw is threaded into the support or housing |0. The other end of the spring 42 is 'connected to. a lever portion 45 of theocontact carrying member 26, preferably by a loop portion 41 of the spring 42 that is disposed in a notch 48 in the end of the contact carrying member. The end of the spring .42 near the loop portion 41 is disposed within an opening 50 in the contact carrying member, and a curved portion 52 of the Contact carrying'member provides a stop that contacts the spring intermediate the extremities thereof when the contact carrying member is moved in one direction.

The spring 42 normally urges the contact 32 into engagement with a stationary contact 54, which stationary contact is secured to the back or base I 2 of the housing by riveting as at 5.5, or by other suitable fasteninglmeans; The contact A54 is preferably mounted in a recess 56 in the base or back I2, and has a stem portion 58v that extends -through an/opening 60 in the base or back I2. A lug 62 is preferably secured to the contact 54 for making electrical connection to a conductor of an electrical circuit such as 64, which conductor is shownI as-insulated at l66 and con` i substantially V-shaped bi-metallic member, has

one of the legs of the Vanchored between the head of the screw 48 and the spacer 44, while the other leg of the V is similarlyfanchored by 'a screw 12 and similar spacers, not shown. The thermal-responsive element extends along the spring 42, and is substantially parallel thereto.

The free end` of the substantiallyl V-shaped thermal-responsive element has a slot 14 therein. A link 16 has a notch 18 therein', which link is inserted into the slot 14. As best shown in Fig. 5,

a corner'80 is preferably rounded so that the` link may be easily inserted into the slot 14. `The link 16 is also notched at 82, and ts into a slot in the contact carrying member 26 to effect an aosefsc nected to the contact 32 and to the spacer 46 so that a positive connection is provided between the movable contact 32 and the thermal-responsive element. The connection of an electrical circuit to the ``thermal-responsive element is made thru a wire such as 88 which is connected to the ther mal-responsive element by soldering as at 90, or by other suitable connecting means. The wire 88 is indicated as insulated at 82.

With particular reference to Figs. 6 and '1, the switch support comprises'an insulating base |00 that serves as a terminal strip, a substantially U-shaped metallic frame |02 having side walls |04 and |06 and a connecting portion |08, as well as strips of insulating material I I0 and i I2 that are preferably rivetedto angularly extending portions i|4 and ||6 respectively, that are integrall with the side walls |04 and |06. The side walls- |04 and |06 have substantially V-shaped notches i I1 and I I 8, in` one end thereof, and substantially V-shaped notches and |22 in the other endsl thereof. A movable contact carrying member |24 has knife edges such as |26 disposed. in the V-shaped notches |I1 and ||8 to provide a substantially frictionless pivotal mounting/for the contact carrying member |24. A movable con tact carrying member |28 has knife edges at |30 ifi and |32 that are disposed in the V-shaped notches v |20 and |22 to provide a pivotal mounting for contact carrying member l28. The contact carrying members |24 and |28 are connected by a tension spring |34, which spring holds the contact carrying members in position sof that the knife edges rest in their respective notches and provides a component of force that tends to maintain engagementof the contacts. The contact carrying member |24 has a slot |36 therein in which one end of the spring |34 is disposed, and has a hole |38 thru which a hook portion |40 of the spring passes to connect the spring to the c'ontact carrying member. member |28 has a slot |42 therein in which the other end of the spring is disposl, and has a hole |44 thru'which another hoo portion |46 of the spring passes to connect thatend of the spring to the contact carrying member, |28.

One ofthe thermal-responsive elements |48 is securedto the insulating strip ||0 by rivets |50, or other suitable fastening means; and the insulating strip ||0 is secured to the frame |02 by means such as rivets |52. The thermal-responsive element |48 is preferably cut so that it comprises adjacent substantially-parallel strips connected in zig-zag fashion to increase the electrical resistance thereof. The free ends of the thermalresponsive element |48 are connected together by a member 54 that is preferably made of insulating material, and are secured to the member by rivets |56, or other suitable fastening means. 'I'he member |54 has an opening |58 therethrough through which an end portion |60 of a link |62 extends. Another end portion |64 of the link |62 extends through an opening |66 in the contact carrying member |28, so that the link provides an actuating connection between the end |54 of the thermal-responsive*element |48 and thecontact carrying member |28 to effect actuation of the contactcarrying member in one direction responsive to movement of the end of the thermal-responsive element. Another thermal-responsive element |68, similar to the element .|48 has one end anchored to the insulating strip,|| 2 by means such as rivets |10, and the insulating strip ||2 is secured to the frame |02 by rivets |12, or other suitable fastening means.

The other end of the thermal-responsive element |68 is secured to an insulating member |14 by means such as rivets |16. The insulating member |14 has an opening |80 therein through which an end portion |18 of a link |82 extends to provide an actuating connection between the thermal-responsive element |68 and the contact carrying member 24 similar to the actuating connection between the thermal-responsive element |48 and the contact carrying member |28.

Pins |84 and 86 are secured to Contact carrying members |24 and |28 respectively, upon which pins contact arms |88 and |98 respectively, are slidably mounted. The contact arms |88 and |90 are resiliently urged toward the contact carrying members |24 and |28 by springs |92 and |94 respectively, which springs surround the pins and are intermediate head portions |96 and |98 on the ends of the pins, and the Contact arms. Contact points such as 200 are mounted on each -of the contact arms |88 and |90.

Stationary contacts vsuch as 202 are secured in position for engagement with the movable contacts 200 by brackets such as 204, which brackets preferably extend through openings such as 206 in the insulating base |00, the ybrackets are se-v cured to the base |00 by rivets such as 208, or

other suitable fastening means. 204 preferably have portions 2|0 projecting from the base, which portions have threaded holes therein for the accommodation of terminal screws such as 2|2.

Similar stop members 2|6 and 2|8 are secured to the ends of the base |00 and-have portions such as 220 near the ends of the spring |34 against which the spring strikes when moved toward the sto s by the movement of a thermal-responsive ellment. When the spring strikes one of these stops, its effective length is reduced, and with continued movement of the thermal-responsive element, the spring is bent over thev po`rtion `220 of the stop. throughthe stop members 2|6 and 2| 8 and the base |00 beneath the portion 220 to'provide a screw adjustment for regulating the height of the portion 220.

A heater element 224 is disposed intermediate the thermal-responsive elements |48 and |68, and is preferably in the form of a coil having spaced turns. In the particular form shown in Fig. 6, the'heater coil 224 has an end 226 connected to the thermal-responsive element |68 by a rivet 228 or other suitable fastening means. The other end 230 of the heater coil 224 is connected to a connecting lug 232 ythat is provided by one end of the thermal-responsive element C|48. It is understood that this heater element may, however, be connected to any desired ,points in the, circuit that provide control responsive to a particular current. :The heater coil- 224 is not shown in Fig. 7, and has been eliminated from that view so that` the other parts of the switch may be more clearly shown.

Terminals 234 and 236 are secured to the base |00 by rivets 238 and 240 respectively, or other suitable fastening means. The terminals are preferably bent so that they project from the basefand they have screws 242 and 244 threaded therein to `provide connecting terminals for making connections to an electrical circuit. The terminal 246 is provided for making connections to one end of the thermal-responsive element |68; and a terminal 248 is provided for making connections to an end of the thermal-responsive element |48. Insulated conductors 250 and 252 The brackets' Screws such as 222 project are connected to the terminals 246 and 248 respectively for makingconnections to an electrical circuit. Flexible conductors 254 and 256 are provided," for making connections to the movable contacts through the contact arms |88 and |98 respectively. As shown in Fig. 8, the conductor 258 has one end soldered to the contact arm |90 at 258, and has its other end intermediate the screw 222 and stop 220.

With particular'reference to Figs. 9 to 14 inclusive, a support comprises a base 260 and a substantially U-shaped frame 282 that is secured to the base by a rivet 264, or other suitable fastening means. The frame 262 has sides 266 and 268, which sides are provided with inwardly extending portions 210 and 212 to which a strip of insulating material 214 is secured by rivets 218, or other suitable fastening means. The thermal-.responsive element 218 has one end anchored to theinsulating strip 214 by means such as rivets 280. The thermal-responsive element 218 is preferably cut so that it has substantially parallel portions connected in zigzag fashion to increase the electrical resistance thereof, and has terminal portions 282 and 284 integral with the ends thereof. The other ends of the thermal-responsive element 218 are secured to an insulating member 286 by means such as rivets 288. l

The sides 268 and 288 have substantially V- shaped notches 290 and 292 in the ends thereof; and upwardly projecting portions 291| and 298, that are preferably integrally formed with the frame 282, have similar substantial V-shaped notches 298 and 300 respectively therein. A movable contact carrying member 302 has knife edges 394 and 308 that are disposed inthe notches r29|l and 298 respectively to provide a pivotal mounting for that contact carrying member. A movable contact carrying member 308 has knife edges 3|0 and 3|2 that, in cooperation with the notches l300 and 292 respectively, provide a pivotal mounting for the contact carrying member 308. Springs 3| 4 and 3| 6 have hook portions 3|8 and 320 at the ends thereof that are disposed in notches 322 and 324 of the conwtact carrying members 302 and 308 respectively, to connect the springs to the contact carrying members. 'Ihe springs 3|4 and 3|@ are preferably tension springs and have.

their other ends anchored, so that they hold the bers 302 and 308 respectively. When the contact carrying members 302 and 308 are moved downwardly, as viewed in the drawings, the springs 3|4 and 3|6 strike the stop portions 326 and 328 respectively, so that the effective lengths of the springs are decreased, and the springs are bent over the stop portions as the downward movement progresses.

Contacts 330 and 332 are mounted on the contact carrying members 302 and 308 respectively, and are movable therewith. Each of the contacts 330 and 332, has a head portion 334, a stem portion 338 and a smaller stemportion 338. rIhe smaller stem portions 38 are slidably mounted in openings 340 in the contact carrying members 302 and 308, and are long enough to permit some axial movement of the contacts. Connecting lugs 342 are secured to the smaller stemportions 338 of the contacts by soldering or riveting as at 344. Springs 346 surround the stem portions 336 intermediate the head porthermal-responsive element 218.

`of the heater element to the terminal.

tions 334 and the contact carrying members to urge the head portions 334 away from the contact carrying members. Cooperating stationary contacts 348 and 350 are secured to brackets 352 and 354 respectively, which contacts are in alignment for engagement with the contacts 330 and 332 respectively. rlhe brackets 352 and 354 extend through openings 356 and 358 re-. spectively, in the base 260 and have portions 360 and 362 that project from the base to provide terminals into which terminal screws 364 and `366 are threaded.

A link 368 has projecting tips 310 that extend through holes 312 in the insulating strip 2867 and are bent to secure the link 368 to the insulating strip 286. rlf'he link 368 is notched so that it has a shoulder 31.4 that engages one side of the contact carrying member 302 to effeet movement of the contact carrying member in one `direction in response to flexure of the The link is also notched so that it has shoulders 316 and 318 that engage the contact carrying member 308 to effect movement of that contact carrying member in either direction in response to fiexure of the thermal-responsive element. A heater element 380 that preferably comprises aresistance wire formed in zig-zag fashion is closely associated with "one surface ofthe thermal-responsive element 218. One end of the heater element 380 is secured and electrically connected to a terminal 382 that is preferably integrally formed with the side 266, which terminal has a screw 384 threaded therein for .securing the end The other end of the heater element 380 is secured and electrically connected to the binding post 386 by a screw 388 that is preferably threaded into the binding post. The binding post 386 is preferably insulatingly secured to the base 260.

The contacts 330 and 332 are preferably positively connected to the frame 262 by leads 390 and 392 that are connected to the lugs 342, preferably extend through the springs 3|4 and 3| 6' respectively, and are connecte/d to the frame 262 as by soldering at 394. The terminal 360, and the particular switch shown in the draw-4 ings, is connected to the end 282 of theI thermalfresponsive element through an insulated wire 396. A terminal 398 that is secured to the base 260 by a rivet 400 and preferably has a screw 402 threaded therein, as well as insulated wires 404, 406 and 408 are provided for making electrical connections to the circuit to be controlled vby the switch.r

`'With particular reference to Fig. 15, thel thermal-responsive switch shown is a diagrammatic representation of the switch shown in Figs. 9 to 14 inclusive, and reference numerals similar to those previously used in describing that switch refer to similar parts that perform similar functions. The end 284 of the thermal-respon sive element is connected to one end of an auxiliary' or starting field winding 4 I 0 of a motor 4I2, which motor also has a main field winding 4I4 and a rotor 4 I6 that is preferably of the squirrelaoaarse carrying members 302 and 308, respectively. The other end 282 of the thermal-responsive element is connected to the stationary contact 348, and the other power supply line wire 420 is connected to the other stationary contact 350.

With particular reference to Fig. 16, a power supply line wire 430 is connected to one end of a starting or auxiliary eld winding 432 and to one end of a main field winding 434 of a motor 436 having a rotor 438 that is preferably of the squirrel cage type. The other end of the auxiliary eld winding is connected to a stationary contact 440 of a thermal-responsive switch 442; while the other end of the main field winding is connected to one end of a thermal-responsive element 444 that has one end anchored at 446 and has a contact 448 actuated by the other end and in alignment for engagement with the contact 440. A heater element 450 has one end connected to the thermal-responsive element 444 and its other end connected to a heater element /f 452 of a switch 454, either of which heater ele- A ments may be separate resistance units or the with a stationary contact 462, which stationaryV contact is connected through a main control switch 464 to the other power supply line wire` 466. The main control switch 464 has a contact 468 andA a cooperating movable contact arm 410. 5 l

With particular reference to Fig. 17, a power supply line wire 480 is connected through a main control switch 482 to one end of a starting or auxiliary field winding 484 and to one end of a main field Winding 486 of a motor 481 having a rotor 488 that is preferably of the squirrel cage type.

The main control switch 482 has the contact 490 and a cooperating movable contact arm 492, The other end of the main field. winding 486 is connected to a movable contact arm 494 of an electromagnetically actuated switch 496, and the movement of the contact arm 494 is preferably f controlled by a dash-pot 498'. The other end ofthe auxiliary field winding 484 is connected toa -stationary contact 500 that is in alignment for engagement with the contact arm 494. An velectromagnet 502 is magnetically associated with the movable contact arm 494 to actuate the arm,

`and has one end connected to vthe contact arm 494 and its other end connected to one end oi.' a heater elementv 504; The other end of the heater element 504 is connected to an end of a thermalresponsive element 506 that is part of a thermal-- responsive switch 508. The heater element 504 may be either a separate resistance unit or the inherent resistance of the thermal-responsive ele- Y ment itself. One end of the thermal-responsive element 506 is anchored at 5| 0., and the other end actuates av contact 5|2 that is in alignment for engagement with a stationary contact 5I4. The stationary contact, 5I4 is connected tol another power supply line wire 5|6.

The thermal-responsive switches shown in Figs. 16-and 17 are preferably similar to those shown in Figs. 1 to 4 or Figs. 9 and 10.

In the operation of the switch shown inFlgs. 1 to 4 inclusive, the contacts 32 and 54 are normally biased, into engagement by a component of the .force exerted by the spring 42 that is connected 75 tothe movable contact carrying member 26. With the particular switch illustrated, the thermal-responsiveelement 10 is connected in series with an electrical circuit,in response to the current in whichcircuit the switch is controlled. It is understood, however, that the thermal-responsive element may be controlledv by the temperature of any desired surrounding medium or heater element. When the thermal-responsive element iiexes toward the contact carrying member 26, that contact carrying member is actuated through the link "16 to open the contacts.` When the switch is in the contact closed position, as shown in Fig. 3, the spring 42 exerts its maximum force to hold the contacts in engagement.

Hence, before movem-ent of the contact carrying member 26 can be effected by the thermal-responsive 'element 10, suicicnt energy must be built up in the thermal-responsive `element to overcome the force of the spring 42 and start movement of the contact carrying member. When movement of the contact carrying member is begun, the component of the force of the spring 42 that resists such movement of the thermalresponsive element diminishes as the movement of the contact carrying member progresses. Since the contact 32 is resiliently mounted, the contacts 32 and 54'remain in engagement for a short interval of time after movement of the Contact carrying member is started, and since the speed of movement of the contact carrying member increases with the distance of movement, a quick or snap break of the contacts is effected.

As the motion of the end of the thermal-responsive element progresses toward the contact carrying member, the end of the spring 42 that ,is connected to the contact carrying member moves in the same direction. After a predetermined movement of the end of the spring in that directiomand after the contacts are disengaged, the stop portion 52 of the contact carrying member engages the spring intermediate the extremitiesl thereof and acts as a fulcrum about which the spring is bent upon further movement of the contact carrying member in the same direction. This engagement of the stop portion 52 and the l spring decreases the effective length thereof, so

that the spring resists further movement of the conta-ct carrying member in a manner similating a constant load or resisting force. The stop portion 52 prevents the aXis of the spring 42 from crossing the pivotal axis of the contact carrying member, so -that the spring 42 continually resists the movement of the contact carrying member in one direction, and effects movement of the contact carrying member in the other direction when the thermal-responsive element iiexes in the reverse direction. l

In the operation of the dual switch shown in Figs. 6 to 8 inc1usive,`the' separate switch units operate in substantially the same manner as that described for the switch shown in Figs. l to 4 inclusive. In this dual switch, however, a single frame is utilized for supporting the two switches and a single spring |34 biases the movable con- ,tact carrying members of both switches. In the switches of this dual unit also, the stops 220, against which the biasing spring strikes, are mounted on the base and are adjustable, instead of being integral with the movable contact carrying members. y

In the dual switch shown in Figs. 9 to 14 inclusive, both movable contact carrying members are actuated by a single thermal-responsive element. The link that provides the actuating connecticn between the thermal-responsive element and the contact carrying members is preferably notched to provide shoulders 314 and 316 that are not in alignment so that the actuation of the contact carrying members is eiected at different time intervals, or at different points of flexure of the thermal-responsive element. It is understood, however, that the link can be so notched that it provides a dierent sequence of operation of the contacts, or so that they operate at substantially the same time.

In the particular' form shown, the contact carrying member 302 is actuated by the thermalresponsive element 21213 in substantially the same manner as described for the switch shown in Figs. i to 4 inclusive. 'I'hat is, the contact carrying member 302 is actuated to a position such as that indicated in Figs. 11 and 13 without actuating the contact carrying member 308. Continued flexing of the thermal-responsive element in the same direction moves the contact carrying member 302 to a position such as that indicated in Figs. 12 and 14, and also actuates the contact carrying member 308 to a position such as that indicated in Fig. 14. After the contact y carrying member 302 has been moved to theV position indicated in Fig. 13, the thermal-responsive element must build up suiicient energy to overcome the resisting :torce of the spring 316 before movement of the contact carrying member 308 is started. Since, in the form shown, it is desirable that the contacts 330 and 348 engage prior to the contacts 332 and 350, the stop portion 326 engages the spring 3| 4 before the axis or" that spring crosses the pivotal axis of the contact carrying member 302; while the stop 328 preferably engages the spring `316 at or slightly beyond the point at which the axis of the spring crossesthe pivotal axis of the contact carrying member 308. Hence, the shoulder 318 is provided on the link '368 to start the return movement of the Contact carrying member 308.

Fig. 15 diagrammatically illustrates the application of--the dual switch shown in Figs. 9 to 14 inclusive, .to the control of an electric motor. In this circuit, the movable contact carrying member 302 and the contacts 330 and348 controlthe starting and running circuits of the motor; while lthe contact carrying arm 308 and the contacts 332 and 350 protect the motor against overload, or some such abnormal condition that might be harmful to the motor. As illustrated, the circuit shows a split phase type of single phase alterhating current motor; although itis understood jthat a similar control circuit might be applied to other types of motors.

In the operation of the circuit shown in Fig. 15, the ystarting or auxiliary eld winding current flows through the thermal-responsive element to directly effect heating of the thermal-responsive element; While the, main eld winding current ows through the heater element 3,80 that is closely associated with the thermal-responsive element so that the heating of the heater element 380 also heats the thermal-responsive element. When the motor is not running, the switch contactsV are normally in the position illustrated in Fig. 15. When a source of current is connected to the motor through the power supply line wires 4I!!- and 420, the circuits are closed to both the main and auxiliary eld windings. the rotor speed increases in the starting of the motor, the thermal-responsive element is heated to a suiiicient degree that by thetime the rotor has reached a predetermined speed, the' thermall'70 However, as

Cil

responsive element has flexed sufficiently to effect disengagement of the contacts 330 and 348 to open. the circuit to the auxiliary eld winding, thus switching from the starting to the running circuit of the motor. The heater element 388 is preferably so designed and positioned that the normal main iield winding current at full load, or less than full load, does not cause iiexure of the thermal-responsive element an amount suicient to cause disengagement of the contacts 332 and 350, but it does provide suiicient heat so that the thermal-responsive element" remains sufliciently exed to maintain the contacts 330 and 348 in their disengaged position. Such an abnormal cooled sufiiciently that the thermal-responsive.

element flexes back to its normal position to permit the contacts to close. If the overload or abnormal condition still remains, the motor will -again be started and stopped in a similar manner.

VIt is desirable that the contacts 330 and 348 close prior to or simultaneously with the contacts 332 and 350, so that the main eld winding alone will not be connected Aacross the power supply line wires 418 andv 420 when the motor is stopped.

The circuit shown in Fig. 16 operates in a manner similar to that described for Fig. 15, except that separate control switches having separate thermal-responsive elements are utili'zed to accomplish vthe starting and overload control. In this instance, the thermal-responsive elements differ in characteristics so that the thermal-responsive element 444 and the heater element 450 effect control of the starting and krunning circuits, while the switch 454 remains closed until some abnormal condition :such as an excessive overload on the motor occurs. Switches such as that illustrated in Figs. 1 to 4 inclusive, having thermal-responsive elementsn with different operating characteristics are adapted to be used in a system such as illustrated in Fig. 16.

The circuit illustrated in Fig. 17 operates in a manner similar to that of the circuit of Fig. 16, except thata dashpot controlled magnetic switch is utilized for controlling the circuit to the starting or auxiliary field winding 484i AFrom the foregoing description of the construction and mode of operation of the present control djevicelt will be apparent that the unit comprises chieiiy a support I to'which is secured a statinary contact 54, a movable contact 34 adapted to engage `the stationarycontact 54, which movable contact 34 is mounted Aon a pivotally supported contact carrying member 26 and insulated from the stationary contact 54, a spring 42 anchored at one ,end and having its other end 41 connected to the contact carrying member 26, a thermal responsive element 1,0 anchored at one end near the anchored end of the spring 42, said thermal responsive element l0 'and spring 42 being substantially parallel to each other, the pivotal mounting 24 for the contact carrying member 26 being nearer the end v4l of the spring 42 that is fastened to the contact carrying member 26 than to' the other end of the spring, and said accepta spring 42 exerting a continuous force against the movement of the thermal responsive element in one direction, the magnitude of which force diminishes after movement is started and continues to diminish until after the contacts 54 and 34 are broken.

In an embodiment of the dual switch, it will be apparent that the device comprises chieiiy a support 260, stationary contacts 348 and`350 secured to the support 260, movable contact carrying members 302 and 308 pivotally mounted at 290 and 298 and 300 and 292 respectively and having contacts 330 and 332 mounted thereon for engagement with the stationary contacts 348 and 350 respectively, said contacts 330 and 332 being electrically insulated from the contacts 348 and 350, a thermal responsive actuating element 218 anchored at one end at 280 and operatively connected to the contact carrying members 302 and 308 by an intermediate member368 so that the contact carrying members 302 and 308 are actuated at different times responsive to the thermal responsive element 218, and springs 314 and 3I6 each anchored at one end and having their other ends connected to the contact carrying members 302 and 308.

These combinations possess the following advantages:

1. Quick breaking of the contacts responsive to a thermal responsive element.

2. Capability of control responsive to current in a circuit or the temperature of a surounding medium, or both.

3. Control of a plurality of contacts in a predetermined sequence responsive to a thermal responsive element.

4. Compactness of the assembly'.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A switch comprising, in combination, a support, a stationary contact secured to the support, a pivotally mounted movable contact carrying member insulatingly mounted with respect tothe stationary contact and having a contact mounted thereon for engagement with the stationary contact; a spring anchored at one end and having its other end connected to the contact carrying member, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact 'carrying member so that actuation of the contact carrying member in one direction is effected by the thermal-responsive element, and a stop engaging the spring intermediate the extremities thereof to shorten the effective length of the spring after predetermined movement of the contact carrying member and spring.

2. A switch comprising, in combination, a support, a stationary contact secured to the support, a pivotally mounted movable contact carrying member insulatingly mounted with respect to the stationary contact and having a contact mounted thereon for engagement with the stationary contact, a spring anchored at one end and having its other end connected to the contact carrying member, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact carrying member so that actuation of the contact carrying member in only one direction is effected by the thermal-responsive eleaccerta ment, and a stop engaging the spring intermediate the extremities thereof so that the spring substantially continuously urges the contact carrying member toward the thermal-responsive element.

y 3. A switch comprising, in combination, a support, a stationary contact secured to the support, a pivotally mounted movable contact carrying member'insulatingly mounted with respect to the stationary contact and having a contact mounted thereon for engagement with the stationary contacts, a spring anchored at one end and having its other end connected to the contact carrying member, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact carrying member so that actuation of the contact carrying member in one direction is effected by the thermal-responsive element, and

a stop integral with the contact carrying member for engaging the lspring intermediate the extremities thereof to shorten the effective length of the spring after predetermined movement of the contact carrying member and spring.

4. A switch comprising, in combination, a support, a stationary contact secured to the support,

a pivotally mounted movable Contact carrying member insulatingly mounted with respect to the stationary contact and having a contact mounted thereon for engagement with the stationary contact, a spring anchored at one end and having its other end connected to the contact carrying member, a bimetallic thermal-responsive element anchored at one end near the anchored end ci the spring, said thermal responsive element and spring being substantially parallel to each other, the pivotal mounting vfor said contactycarrying member being nearer the end of the spring that is fastened thereto than to the other end thereof, and said spring exerting a continuous force against the movement of the thermal-responsive element in one direction, the magnitude of which force diminishes after movement is started and continues to4 diminish until after the contacts are broken,

5. A switch comprising, in combination, a support, a lstationary contact secured to the support, `a pivotally mounted movable contact carrying member insulatingly mounted with respect to the stationary contact and having a contact mounted thereon for engagement with the stationary contact, a spring anchored at one end and having its other end connected to the coritact carrying member', a bimetallic thermal-responsive element anchored at one end near the anchored end of the spring, said thermal-responsive element and spring being substantially parallel to each other, the pivotal mounting for said contact carrying memberbeing near the end of the spring that is fastened'thereto, said spring exerting a substantially continuous force against the movement of engagement with one of the stationary contacts, springs anchored at one end and each having its other end connected to one of the contact carrying members, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact carrying members so that actuation of each of the contact carrying members in one direction is eiiected by the thermalresponsive element and a stop engaging one of the springs intermediate the extremities thereof so that the spring exerts a substantially continnous force on the contact carrying member toward the 'thermal-responsive element.

I'7. A switch comprising, in combination, a support, a plurality of stationary contacts secured to 'the support, a plurality of pivotally mounted movable contact carrying members insulatingly mounted with respect to the stationary contacts and each having a contact mounted thereon for engagement with one of the stationary contacts, springs anchored at one end and each havingits other end connected to one of the contact carrying members, a thermal-responsive element anchored at one end, a link operatively connecting the other end oi the thermal-responsive element to the contact carrying members so that actuation of each of the contact carrying members in one direction is effected by the thermal-responsive element said link eiecting actuation of the contacts at different times, and a stop engaging each oi' the springs intermediate the extremities thereof to shorten the effective length of the springs after lpredetermined movement of the contact carrying members and springs.-

8. A switch comprising, in combination, a support, stationary contacts secured to the support. rst and second contact carrying members each insulatingly mounted with respect to one of the stationary contacts and each having a Contact mounted thereon for engagement with one of the stationary contacts, first and second springs connected at one end to the lrst and second contact carrying members respectively and each having its other end anchored, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact carrying members so that actuation of each of the contact carrying members in one direction is effected by the thermalresponsive element, the actuation of the rst contact carrying member in the other direction being effected by the irst spring and the actuation of the second contact carrying member in the other direction being effected by the second spring after being started by movement oi the thermal-responsive element transmitted to the second contact carrying member thru the link.

9. A switch comprising, in combination, a support, a stationary contact secured to the support, a pivotally mounted movable contact carrying member insulatingly mounted with respect to the stationary contact and having a contact mounted thereon for engagement with the stationary contact, a spring anchored at one end and having its other end connected to the contact carrying-member, a thermal-responsive element anchored at one end, a link operatively connecting the other end of the thermal-responsive element to the contact carrying member so that actuation of the contact carrying member in one direction is effected by the thermal-responsive element directly thruthe link and actuation of the contact carrying member in the opposite direction is effected by the spring after being started by move- CII ment of the thermal-responsive element transmitted thru the link, and a stopA engaging the spring intermediate the extremities thereof to shorten the effective length of the spring after movement of the contact carrying member and spring in one. direction.

l0. Aswitch comprising, in combination, a support, stationary contacts secured to the support,

pivotally mounted movable contact carrying.

members insulatingly mounted with respect to the stationary contacts and each having a cotact mounted thereon for engagement with one of the stationary contacts, a thermal-responsive actuating element anchored at one end, an int-er- Imediate member operatively connecting the thermal-responsive element to the contact carrying members so that the contact carrying members .are actuated at different times responsive to the chored at one end and having their other ends connected to the contact carrying' members.

1l. A switch comprising, in combination, a base, a thermal responsive element anchored at one end and having its other end movable due to lexure of said element in response to temperature changes; a tension spring anchored near the anchored end of the thermal responsive element; means connecting the movable end of the thermal responsive element to the other end of therspring; relatively movable cooperating contacts normally engaged, one of which is actuatedby movement of the thermal responsive element; said thermal responsive element, spring and means `being so disposed relative to each other that a Component of the force of said spring continually urges the contacts toward their normally engaged position and such that said component of force of said spring diminishes as movement of the thermal responsive element progresses to effect acceleration of the movement of the thermal responsive elementrafterthe component of force is initially overcome by the thermal responsive element.

12. A switch comprising, in combination, a base, a thermal responsive element anchored at one end and having its other end movable from a normal position due to iiexure of said element.

in response to temperature changes; a spring having one end fixedly anchored; means connecting the other end of the spring to the movable end of the thermal responsive element; said thermal responsive element, said spring and said means.

being so disposed with respect to each other that a component of the force of said spring opposes movement of the thermal responsive element from the normal position thereof; said thermal responsive element, said spring and said means also being so disposed with respect to each other that the said component of force diminishes to eiect acceleration of the movement of the thermal responsive element after movementth'ereof starts; stop means for arresting movement of the thermal responsive element away from normal position and preventing said spring from aiding rspring to the otherl end of the thermal res accerti-i such movement; a pairv of cooperating contacts, one of which is actuated by the thermal respon-A sive element.

13. A switch comprising, incombination, a base, a thermal responsive element anchored at one end and having its other end movable from a normal position'due to flexure of said element in response to' temperature changes; a spring having one end xedly anchored; means connecting the other end of the spring to the movable end of the thermal responsive element; said thermal responsive element, said spring and said means being so disposed with respect to each other that a component of the force of said spring opposes movement of the thermal responsive element from the normal position thereof; said thermal responsive element, said spring 'and said means also being so disposed with respect to each other that the. said component of force diminishes to effect. acceleration of the movement of the thermal responsive element after move mentthereof starts; stop means for arresting movement of the thermal responsive element away from normal position and preventing said spring from aiding such movement; a pair oi" aoperating contacts, one of which is actuatedby the thermal responsive element, and one of which contacts moves toward the other during initial movement toward disengagement.

14. A switch comprising, in combination, a base; a thermal responsive element; a spring means anchoring one end of the thermal responsive element and one end of thev spring to the base; means connecting the other end of the spring to the other end of thethermal responsive element so that the spring is tensioned and eX- erts a component of force against the end of the thermal responsive element to which it is connected; a pair of cooperating contacts, engagement of which is controlled by the thermal responsive element; and stop means for preventing a reversal of direction of said component of spring force against the thermal responsive element.

1'5.- A"4 'switch comprising, in combination, a"

base.; a thermal responsive element; a spring; means anchoring one end `of the thermal responsive element and one end of the spring to the base; means connecting the other end of the nsive element so that the spring is tensioned an exerts a component of Aforce against the end of the thermal responsive element to Whichit is connected;

a pair of cooperating contacts, engagement of which is controlled by the thermal responsive element; vand stop means for preventing a reversal of direction of `said component of spring force against the thermal responsive element, and means urging one of said` contacts toward the other during initial movement of the thermal responsive element against the said component 01j' y spring force.

CALVIN J.

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