US1548006A - Electromagnetic circuit controller - Google Patents

Description

July 28, 1925. 1,548,006

B. w. JoNr-j s ELECTROMAGNETIC CIRCUIT CONTROLLER Filed, Sept. 9, 1921 Fig.1. 4 Fig.2.

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His Attorney Patented July 28, .1925.

UNITED STATES PATENT OFFICE.

BENJAMIN W. JONES, OF 'SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTROMAGNETIC CIRCUIT CONTROLLER.

Application filed September To all whom it may concern:

Be it known that I, BENJAMIN'VV. Jones, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in ElectromagnetioCircuit Controllers, of which the following is a specification.

My invention relates to electromagnetic circuit controllers which are intended to be operated between two positions responsively to the corresponding operation of a master switch, particularly a master switch which may move slowly between its limits of open ation, such for example, as a thermostat or a pressure regulator which operates as a master switch. One of the diificulties encountered in the use of such a master switch is that of arcing at its circuit controlling contacts, particularly when breaking an inductive circuit such as a windingcircuit, because .of the slow motion of the master switch. One of the objects of the invention is to provide an arrangement which obviates this difficulty and one which is nevertheless simple in construction, reliable in operation, and cheap to manufacture.

In order to obviate the burning of the contacts, I provide an arrangement in which the winding of the electromagnetic switch controlled by the master switch is shunted, short circuited or otherwise deenergized when the electromagnetic switch has operated to the position corresponding to the position of the master switch. In carr ing my invention into effect in a preferred orm of electromagnetic circuit controller for an electric translating device, the electromagnetic switch is provided with two windings, one'for closing the switch and the other for opening the switch, although the invention is not necessarily limited in its application ,to a two winding switch. The windings are controlled by the master switch and the connections preferably are such that the closing winding is energized; in series circuit with the translating device while the opening winding is energized in parallel circuit with the device. Furthermore, the operating winding for the closing direct-ion is short circuited through the-switch member of the electromagnetic switch when the switch member reaches the closed position, and the opening1 winding is deenergized responsively to t e opening of the switch.

9, 1921. Serial .NO. 499,418.

The master switch is thus required to com plete but is relieved of the necessity of opening the circuit through the operating winding with full current through the winding, and the burning at the contacts of the master switch is thus obviated. In order to insure that the winding circuits of the switch will be opened as soon as the switch has operated and also to insure that the winding circuits will be maintained open between the intervals of operation, auxiliary switch mecha nism operated responsively to the operation of the electromagnetic switch may be provided if desired.

For a better understanding of the invention, reference is had to the accompanying drawing wherein I have shown several simplified embodiments of the invention for the purpose of illustrating the principles thereof. Referring to the drawing, Fig. 1 shows an embodiment of the invention in the control of a direct current motor in which the electromagnetic switch directly connects the motor to the supply circuit; Fig.- 2 is a modification of the arrangement ot Fig. 1

in which the electromagnetic switch controlled by the m-aster switch is used as a relay controlling the winding of a line coutactor; Fig. 3 shows an embodiment of the invention in which the electromagnetic switch functions as a relay to control the winding circuit of an electromagnetic line switch for a three phase motor; and Fig. 4c is a modification ot the arrangen'ient of Fig. 3 in which the electromagnetic line switci is provided with two poles for controlling two of the line conductors leading to a three phase electric motor, and the auxiliary switch mechanism previously mentioned is provided.

Referring to Fig. 1, the electromagnetic switch 10 is provided with a switch member- 11 which is operable from the position shown to its upper position in which it makes engagement with the stationary contact 12. The switch member 11 is pivotally mounted in the stationary support 13 and is biased to the position to which it is last operated by means of the over-center device comprising the spring 14 which surrounds the pin 15, one end of which passes through an aperture in the stationary support and the other end of which is pivotally connected to the switch member 11. The electromagnetic switch, in the embodiment shown, is provided with two operating windings 16 and 17, and these operating windings are controlled by means of the master switch 18 which is operable between two definite positions. At one of its definite positions the master switch is adapted to make engagement with the stationary contact 19, and at the other of its positions it is adapted to make engage ment with the stationary contact 20. The master switch is shown as a circuit controlling thermostat, and it will be understood by those skilled in the art that while rny invention is particularly applicable to the control of the electric motor 21 responsively to changes or temperature, the invention is not necessarily limited thereto. The thermostat 18 moves slowly between its limits of operation, and one of the objects of the invention is to eliminate all arcing or burning at the theremostat due to breaking the highly inductive circuit of the windings of the electromagnetic switch 10.

The operation of the arrangement as thus constructed and arranged, and with the parts in the position shown in Fig. 1, is as follows z-Assume that the thermostatic master switch 18 is operated so that its upper end makes engagement with the stationary contact 20. A circuit for the switch winding 16 is thereby completed from the supply conductor 22, through the winding 16, contact 20, thermostat 18, and thence in series circuit through the motor 21 to the other supply conductor 23. The movable magnetic member or plunger 24 of the switch is pivotally connected to the switch member 11 so that upon the energization of the winding 16 the switch member 11' will be moved over center against the strain of the spring 14; and then the switch contacts are given a quick wiping engagement when the spring is relieved after the switch member passes the dead center position. The

circuit for the electric motor 21 is thereupon I completed, and the winding 16 is short circuited through the switch member 11 when the switch member is in the operated position. 'The winding 16 is thus substantially deenergized and the thermostat is not called upon to break the winding circuit. When the temperature changes and'the thermostat is moved to make engagement with the stationary contact 19, the winding 17 is energized in parallel with the motor 21 through a circuit including the stationary contact 12, switch member 11, thermostat 18, contact 19 through the winding 17 to the other supply conductor 23. The plunger 2 1 will thereupon be attracted to move theswitnh member 11 against the strain of the spring 14 past the dead center position .whereupon the spring returns the switch member to the position shown in the drawing. The opening" of the switch includes the winding 17 in a local circuit across the motor and the winding is therefore deenergized when the motor stops, thus relieving the thermostat of the necessity of opening the circuit of the winding since the winding is effectively short circuited. It will be observed that the arrangement is such that it is impossible to maintain either one of the windings of the electromagnetic switch energized with normal operating current except for the brief interval during which the switch member is thrown from one operative position to another. Thus, with the parts in the positions shown in Fig. 1, if the thermostat 18 makes engagement with the stationary contact'19, the winding 17 of the switch cannot be energized, and with the electromagnetic switch 10 in the closed position, the winding 16 also cannot be energize-d with normal operating current. This compels a definite sequence of the energization of the switch windings and prevents undesirable heating of the switch windings.

In the embodiment of the invention shown in Fig. 2, the electromagnetic switch 10 functions as a relay controlling the winding circuit of the electromagnetic line switch 25. The operation of the arrangement is essentially the same as that of Fig. 1. When the thern'iostat 18 makes engagement with the stationary contact 20, the switch winding 16 is energized to cause the switch member 11 to make engagement with the stationary contact 12, thereby energizing the electromagnetic line switch 25 to close. The closing of the electromagnetic line switch 25 momentarily shortcircuits the switch wind ing 16 through a circuit including the thermostat. When the line switch 25 is closed, the winding 17 can then be energized through the thermostat to open the relay 10 and thereby deenergize the line switch. The

opening of the line switch includes the wind-- ing 17 in a local circuit to the motor, as before.

In the embodiment of the invention shown in Fig. 3, the electromagnetic switch 10 also functions as a relay controlling the windstat 18 makes engagement with the stationary contact 20, the winding 16 is energized through a circuit from the middle conductor of the three-phase supply 28, through the winding 16, thermostat 18, through the winding of the electromagnetic line switch 26 to the upper supply conductor. The resistance of the winding of the line contac-' tor 26 is adjusted so as to be comparatively small as compared to the resistance of the winding 16, and the winding 16 will therefore be sufficiently energized to operate the relay 10 to the closed position. When the movable contact 11 of the relay makes engagement with the stationary contact 12, the winding 16 is short circuited, thereby relieving the thermostat 18 of the necessity of breaking the circuit. The electromagnetic line switch 26 will be energized to close and connect the motor 27 to the source of su ply. With the relay l0 closed, in case t e thermostat 18 makes engagement with the stationary contact 19, the winding 17 of the relay will be energized across the two upper conductors of the threehase supply and the relay 10 will thereby be operated to the open position, thus deenergizing the electromagnetic line 26 and. disconnecting the motor from the source of supply. The winding 17 is included in a local circuit with the winding of the line switch 26, and both windings are promptly deenergizcd.

- The arrangement of Fig. 1 is essentially the same as that of Fig. 2, with the exception that the electromagnetic line switch 31 is of the two-pole type, the motor is permanently connected to the lower conductor of the three-please supply, and auxiliary switch mechanism 29---3O is included in the winding circuits of the relay 10. The purpose of the auxiliary switch mechanism is to insure that a circuit will never be completed between the contacts 19 and 20. In thermostatic control devices as ordinarily constructed the distance between the contacts 19 and 20 israther small and these contacts are ordinarily made adjustable so as to adjust the device for the desired temperature range of operation. In case these contacts were unintentionally adjusted so as to complete a circuit through each other through the themostat, the windings 16 and 17 would be included in series across a phase of the supply circuit. The auxilia switch mechanism 29-30 prevents this, since one of the switches is always open. With the parts in the positions shown in the drawing, when the thermostat 18 makes engagement with the stationary contact 19, the wmding 16 of the relay will be energized from the upper supply conductor through the auxiliary switch 30, to the thermostat 18, through the motor, to the lower su ply conductor. :The

be energized to close and ener ize the line switch 31 to close to connect t e motor to the source of supply. The closing of the relay short circuits the winding 16, and the short circuit about the winding is opened at the auxiliar switch 30 which is opened by the closing 0 the relay.

. The auxiliary switch "29 is closed by the closmgofthe relay. With the relay 10 and the line switch 31 closed, in case the thermostat 18 makes engagement with the stationary contact 20, the winding 17 of the relay will be energized across theiupper and lower supply conductors to open the relay and thereby deenergize the line switch 31. When the relay opens the winding 17 is included ina local circuit with the motor and is thus deenergized.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the'apparatus which I now consider to be the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A circuit controller comprising an electromagnetic switch having a switch member operable between two positions, a master switch operable between two positions for controlling the said electromagnetic switch, and connections whereby when the master switch is operated from either position to its other position the electromagnetic switch is energized to operate to a corresponding osition and the operating winding thereof 1s short circuited in the operated position.

2. A circuit controller comprising an electromagnetic switch having a switch mem ber operable between two positions, a master switch operable between two positions for controlling the said electromagnetic switch, and connections whereby when the master switch is operated from either position to its other position the electromagnetic switch is energized to operate to a corresponding position and the operating winding thereof is included in a. local circuit with the said master switch in the operated position to deenergize the winding. 7

3. A circuit controller comprising an electromagnetic switch having a switch member operable between two positions, means for biasin the same to each position when operated t ereto, a master switch operable between two positions for controlling the said electromagnetic switch, auxiliary switch mechanism operated responsively to the operation of the electromagnetic switch for deehergizing the windings of the electro- -magnetic switch and connections whereby whenthe master switch is operated from one position to its other position the electromagnetic switch is energized to operate to a corresponding position and the operating winding thereof is short circuited and the circuit through the said winding is then opened by the said auxiliary switch-mechanism.

4. A circuit controller comprising an electromagnetic switch having a switch member operable between two positions and biased to eachposition when operated thereto, the

said switch having two windings, one for operating the switch to one position and the other for operation to the other position, a master switch operable between two posi tions for controlling the said windings, and connections whereby when the master switch is operated to either of itspositions,

'the corresponding winding of the said electromagnetic switch is energized to operate the electromagnetic switch to a corresponding position and the said winding is short circuited when the electromagnetic switch is in the operated position corresponding to the position of the master switch.

5. A circuit controller comprising an electromagnetic switch having a switch member operable between two positions and biased to each position when operated thereto, auxiliary switch mechanism controlled by the said switch member, a thermostat operable between two positions for controlling the said electromagnetic switch, and connections whereby when the thermostat is operated from either position to its other position the electromagnetic switch is energized through the said auxiliary switch mechanism to operate to a corresponding position, the operating winding thereof is short circuited in the operated position and the auxiliary switch mechanism is operated to open the circuit through the said operating winding.

6. A circuit controller for an electric translating device comprising an, electromagnetic switch having a switch member operable between two positions, a master switch operable between two positions for controlling the said electromagnetic switch, and connections whereby when the master switch is operated to one position the electromagnetic switch is energized in series circuit with the controlled translating device to operate to a corresponding position and when the master switch operated to the other of said positions the electromagnetic switch is energized in parallel circuit with the controlled device to operate to a corresponding position.

A circuit controller for an electric translating device comprising an electromagnetic switch having a closing winding and an opening winding, a master switch operable between two positions for controlling the said electromagnetic switch and connections whereby when the master switch is operated to one of its positions, the closing winding of said electromagnetic switch is energized in series circuit with the controlled translating deviceand when the master switch is operated to the second of said positions, the opening winding of said electromagnetic switch is energized in parallel circuit with the controlled device.

8. A circuit controller for an electric translating device comprising an electromagnetic switch having a closing winding and an opening winding, :1. master switch operable between two positions for controlling the said electromagnetic switch, and connections whereby when the master switch is operated to one of its positions, the closing winding of said electromagnetic switch is connected in series circuit with the controlled device to a source of supply to operate the switch to close a short circuit around the said closing winding and the said master switch and when the master switch is operated to'the second of its positions the opening winding of said electromagnetic switch is energized in parallel circuit with the controlled device to operate the switch to disconnect the said opening winding and the said translating device from the source of supply.

In witness whereof, I have hereunto set my hand this 8th day of September, 1921.

BENJAMIN W. JONES.

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