US1543408A - Thermally-operated circuit controller - Google Patents

Description

G. H. WHITTINGHAM TBERMALLY OPERATED CIRCUIT CONTROLLER June 23, 1925.. 1,543,408

Filed Aug. 29, 1922 Patented June 23, 1925.

. UNITED STATES PATENT OFFICE.

GEORGE H. WHITTINGHAM, OF BALTIMORE. MARYLAND, ASSIGNOR TO MONITOR CONTROLLER COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARY- LAND,

THERMALLY-OPERATED CIRCUIT CONTROLLER.

Application filed August 29, 1922. Serial No. 584,939.

T 0 all whom it may concern:

Be it known that I, Gnoncn H. \VHITTIXG- HAM, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Thermally-Operated Circuit Controllers, of which the following is a specification.

This invention relates to improvements in thermally operated relays for controlling electric circuits. The relay is adapted particularly for use in connection with electric motors, as a load limit device, to cause the main switch or contactor to open and dis connect the motor from the supply circuit in case of overloading of one or more of the motor circuits. various other uses. In the present invention, the relay is adapted to open the controlled circuit when the thermostat is heated and to leave this circuit 0 en when the thermostat cools, the relay t us serving the function of a cut-out in the controlled circuit.

The invention comprises a base of insulating material upon which the several parts, with the exception of the heating elements, are mounted, these parts including a bracket projecting above and extending over the base, a contact lever fulcrumed against this bracket, a spring interposed between the base and the lever at one side of its fulcrum point, said spring tending to rock the lever toward its closed position, and one or more thermal expansion elements interposed between the base and the lever, at the opposite side of the fulcrum point, and adapted to rock the lever to open position, against the action of the spring, when said elements or any of them are heated beyond a predetermined degree. A stationary contact member is secured to the base and a metal connector is arranged between this contact piece and the contact lever so that it may be gri ped between these parts by the pressure 0 the spring, when the thermostat elements are contracted, and will be released and dropped instantly out of engagement with the lever when the latter is moved sufiiciently by one of the thermostats to relieve the pressure on the connector. Thus, although the lever is moved very slowly by the thermostats, a quick break in the controlled circuit is provided and the circuit remains 0 en after the the m stat a o ed and the ever has .re-

The relay has. however,

turned to its normal position unless the connector is manually returned to its upper position. The connector is returned manually by a simple re-setting device. Each thermostat comprises a closed metallic chamber filled with an expansible liquid. one wall of the chamber consisting of a corrugated tube which is axially expansible and adapted to actuate the lever. Vertically adjustable sockets are arranged in the base and the expansion elements are supported in these sockets. By adjusting the sockets the ex pansion elements may be adjusted with respect to the contact lever to vary the time of the actuation of said lever by said elements. The heating elements are formed to fit within sockets or casings in the expansion elements. and these heating elements,

which are connected in the circuit or circuits 1 to be protected, may be readily removed and replaced by other similar elements of different current-carrying and heating capacities, according to the current volume in the circuit or circuits to be protected and the heating effect desired in the thermostats.

In the accompanying drawing,

Fig. l is a front elevation of the cut-out, partly in section;

Fig. 2 is an end view of the base;

Fig. 3 is a plan view of the connector;

Fig. 4 is a central vertical section through the cut-out, taken from front to rear;

Fig. 5 is a section on the line 55 of Fig. 4;

Fig. 6 is a central vertical section through one of the thermostats, showing a coiled heating element; and,

Fig. 7 is a perspective view of a stamped heating element.

Referring to the drawing, a represents a base of insulating material upon which the parts of the cut-out, except the heating coils, are mounted. Upon this base is secured an upstanding bracket 6, having its upper end 6 turned forwardly over the base and thence downwardly, as shown. This downwardly turned part of the bracket is shaped to provide a wide tongue I) atits center which enters atransverse slot 1, in a switch lever s, and two bearings 6 in line with the tongue, which bearings form fulcrum points for the lever. The ever comprises a relatively wide part 2 and a longer and narrower part 3, which is bent at right angles to the part 2. The part 2 of the lever is pressed upwardly against the fulcrum points 6 by a spring 4, which is interposed between the base and the rear end of the lever. This spring, as shown, is coiled about a threaded rod 5, which extends through the top of the bracket and into the base. The part 2 of the lever thus occupies a substantially horizontal position, and the arm 3 of the lever extends downwardly in front of the base. The lower part of the arm is preferably made of brass and has an inwardly off-set portion 3 substantially parallel with the major portion of the arm, and an outwardly inclined end portion 3". The part 3 is adapted to bear against a square relatively thick and heavy copper connector 0 to hold this connector, by the pressure of the spring 4, against the downwardly extending part 6 of a fiat metal strip 6, which is secured to the underside of the base. The connector has a central opening 7 preferably countersunk from both sides so that it can drop freely downward on a rod 8, which passes through the opening, and the edges of the connector, which are engaged by the lever and the metal strip, are preferably rounded as shown at 7 so that the connector may drop without hindrance by these parts when the lever moves sufficiently to release the connector. The rod 8 constitutes part of the re-setting device (1. -This rod extends upwardly through a hole 9 in the base, and a nut 8 on the rod above the base serves as a support for the rod. The lower end of the rod carries a knob 8 on to which the connector drops when released by the lever, as indicated in dotted lines in Fig. 4. To place the connector in position to be gripped by the lever it is only necessary to push the resetting device upwardly until the connector lies against the underside of the base. When the re-setting device is released, it drops down and remains suspended on the nut 8. In moving upward, the connector bears against the inclined lower end 3 of the lever and forces it outwardly. In its uppermost position the connector is gripped between the lower end of the vertical part 3 of the lever and the opposing flat contact piece 6".

One terminal 10 of the circuit to be controlled by the cut-out is connected to a bolt 12 which passes through the bracket 6 and secures the same to a switchboard e, and the other terminal 10 of the circuit is connected to a bolt 13 which passes through the contact strip 6 and the switchboard. From the conductor 10 the current flows through the bracket and contact arm to the connector and thence through the contact strip 6 to the conductor 10%....The release of the connector interrupts the circuit and leaves it open until the connector is moved device.

u'pward manually by means of the re-setting device.

Two thermostats f, f are shown for actuating the switch lever in opposition to the spring, each thermostat bcin capable of actuating the lever independ ently of the other thermostat. There may be one or any number of thermostats, according to the number of circuits to be protected by the The thermostats are alike and each comprises an expansion element, supported by the base, and a heating element F, supported upon the switchboard and extending into a casing or socket in the expansion element. As shown, the expansion element comprises an outer annularly corrugated tube 14, connected at one end by a fluidtight joint 15 with a tube 16 which extends into the corrugated tube and has its inner end 16 closed. The corrugated tube has a cap 17 at its free end, this cap having a nipple 17 through which the tube may be filled with an expansible liquid 18. This nipple, after the tube has been filled, is closed by a plug 17. The heating element, as shown in Fig. 6, comprises a coiled wire 19, adapted to fit within the inner tube or casing 16 and having its terminals connected to the metal eyelets 20 in a flat piece of insulating material 21 which supports the coil. For heavy currents, the heating conductor may take the form shown in Fig. 7. In this figure, the conductor is a stamped strip of metal 19 doubled upon itself at the center and having outwardly turned ears 19 which are perforated, as

shown at 20. The strip 19, suitably insulated, is to be inserted in the socket in the expansion element. The heating elements are detachably connected to binding posts 21 which project from the switchboard below the base of the relay, and they are secured to these binding posts by screws 21" which pass through the eyelets 20 or the perforations 20 in the heating elements.

The ex ansion elements are arranged vertically in front of the fulcrum point of the switch lever s, and are adapted to rock the lever in opposition to the spring 4, when these elements, or either of them, re heated. As shown, the base is formed wit threaded openings 22 in which are fitted threaded sockets 23, of insulating material, and the expansion elements are supported in these sockets with the open ends of the inney casings or tubes 16 downward. Upon the u r end of each expansion element is a bus mg 24, of insulating material, which extends through an opening 25 in the horizontal part of the lever in advance of its fulcrum point. These bushings are provided with annular shoulders 24 which rest upon the caps 17 of the corrugated tube. The lever has a transverse rib 2 on its underside which is adapted to be engaged by the shoulders 24' on the bushings when the lever is supported by the expansion elements. The expansion elements may be adjusted toward and from these ribs b sockets 23, and this adjustment is important in order to advance or delay the time in which the thermostat will open the switch with a given current flowing in its heating conductor. When the fluid in the expansion element is heated, the corrugated tube is expanded forciblyagainst the lever and moves the latter to open position. When the liquid cools, the pressure of the spring prevails and the lever is rocked to its closed position so that it may firmly engage the connector, and make a good electrical contact therewith when the connector is raised to its upper position.

If the relay or cut-out is used for controlling the pilot circuit of a switch for connecting a polyphase alternating motor to a supply circuit, the heating elements will be connected in separate circuits of the motor. Thus, in Fig. 1, the conductors 26, 26', are connected through the heating coil of one thermostat, and the conductors 27, 27', are connected through the heating coil of the other thermostat, and these conductors may represent different circuits of a polyphase motor. It will be evident that excessive current flow in either of the circuits will cause the corresponding thermostat to ex- I pand and move the switch lever to release the connector. This will cause opening of the circuit 10, 10, which latter may represent the pilot circuit of the main'switch for connecting the motor to the supply clrcult. It is believed to be unnecessary to illustrate the motor and main switch and their connections since these are well known and the device of the present invention is useful for other purposes than motor control.

The operation of the device will be clear from the foregoing without further description.

What I claim is:'

1. In a thermally operated circuit controller, a switch lever, a spring tendlng to rock said lever in one direction and a plurality of thermostats for rocking said lever 1n the opposite direction, each thermostat comprising a closed chamber contalnlng an expansible liquid and having a tubular annularly corrugated wall adapted bear against said lever, and means for ad usting said chambers independently toward and from the lever.

2. In a thermall operated circuit controller, a base, a fiilcrum supported upon and above the base, a switch lever having a bearing on said fulcrum, a spring bearing upwardly on said lever at one slde of the fulcrum. and a thermostat adapted to bear upwardly onsaid lever at the opposites de of the fulcrum, said thermostat comprising turning the threaded a closed chamber containing an expansible liquid and having a longitudinally expansible tubular wall vertically arranged between the base and the lever.

3. In a thermally operated circuit controller, a base, a fulcrum supported upon and above the base, a switch lever having a bearing on said fulcrum, a spring hearing upwardlyon said lever at one side of the fulcrum, and a thermostat adapted to bear upwardly on said lever at the opposite side of the fulcrum. said thern'iostat comprising a closed chamber containing an expansible liquid and having a longitudinally expansible tubular wall and a socket adjustably mounted in the base and adapted to receive said chamber.

4. In a thermally operated circuit controller, a base, a stationary contact thereon, a switch lever, a spring normally pressing said lever toward said contact, a connector'adapted to be held against the contact by the lever and to drop by gravity when the lever is moved away from the connector, and a thermostat adapted to move the lever in opposition to the spring.

5. In a thermally operated circuit controller, a base, a stationary contact thereon, a switch lever, a. spring normally pressing said lever toward said contact. a connector adapted to be held against the contact by the lever and to drop by gravity when the lever is moved away from the connector, and a thermostat adapted to move the lever in opposition to the spring comprising a closed chamber containing an expansible liquid and having a longitudinally expansible tubular wall and means for adjusting said chamber toward and from the lever.

6. In a thermally operated circuit controller, a base, a stationary contact thereon, a switch lever, a spring normally pressing said lever toward said contact, a connector adapted'to be held against the contact by the lever and to drop by gravity when. the lever is moved away from the connector, a thermostat adapted to move the lever to release the connector, and means for resetting the connector.

7. In a thermally operated circuit controlling device, a base, a stationary contact thereon, a lever having a horizontal part pivotally mounted over the base and a depending part opposed to said contact, a connector adapted to fit between said latter part and said contact, a spring for pressing said lever into engagement with the connector and a thermostat comprising a vertically arranged expansible tube interposed between the base and the lever, for moving the lever to disengage the connector.

8. In a thermally operated circuit controlling device, a base, a stationary contact thereon, a lever having a horizontal part pivotally mounted over the base and a depending part opposed to said contact, a connector adapted to fit between said latter part and said contact, said connector comprising a metal plate having an opening therethrough, a resetting rod extending loosely through said opening and suspended from the base, a spring for pressing the lever into engagement with the connector, and a thermostat on the base adapted to move the lever in opposition to the spring.

9. In a thermally operated circuit controller, a base. a fulcrum supported upon and above the base, a switch lever having a bearing on said fulcrum and extending over and downwardly in front of .the base, said lever having its lower end inclined downwardly and outwardly from the base, a stationary contact on the base, a connector adapted to fit between the lever and contact and to drop by gravity when the lever is moved away from the contact, a spring normally pressing the lever toward the contact, and a thermostat interposed between the base and lever for moving the latter in opposition to the spring.

10. A thermally operated circuit controller comprising a base, a socket vertically adjustable on the base, a contact lever extending over the base and having an opening in line with said socket, a thermostat comprising a longitudinally expansible tube fitting in said socket and having a part extending through said opening, and a spring normally pressing the lever toward said tube.

11. A thermally operated circuit controller comprising a base, a stationary contact, a lever fulcrumed above the base, a spring normally pressing the lever toward the contact, a thermostat, comprising an outer expansible tube and an inner tube, arranged between the base and lever. a heating element projecting upwardly into the inner tube, and binding posts below the tube for supporting said element.

.In testimony whereof I afiix my signature.

GEORGE H. \VHITTINGHAM.

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