US1364944A

US1364944A - Electromagnetic switch

Info

Publication number: US1364944A
Application number: US138020A
Authority: US
Inventors: Mcinnerney Benjamin
Original assignee: Individual
Current assignee: Individual
Priority date: 1916-12-20
Filing date: 1916-12-20
Publication date: 1921-01-11
Anticipated expiration: 1938-01-11

Description

B. Mc|NNERNEY..

ELECTROMAGNETIC SWITCH. APPLICATION FILED nEc.2o. 1916.

1,364,944. P81911161 Jan; 11,1921.

6 SHEETS-SHEET ll I l I I. I

I l I.

WITNESSES: I INVENTQR 76d 4. M Ben bray); Mclnnerney WITNESSES:

B. MclNNERNEY. ELECTROMAGNETIC SWHCH. APPLICATION man 050.20. 1916.

Patented Jan. 11,1921;

6 SHEETSSHEEI 2- myENTo Benjagin Mcfnnemey ATTORNEY B. MclNNERNEY.

ELECTROMAGNETIC SWITCH. APPLICATION FILED oEc.2o, 1916.

1,364,944. Patented Jan. 11, 1921.

SSHEETS-SHEET 3- WITNESSES: INVENTOR 22% d I Benjamin Mcfnnerney B. McINNERNE Y.

ELECTROMAGNETIC SWITCH.

APPLICATION FILED nichzo. 19m.

Patented Jan. 11, 1921.

6 SHEETS-SHEET 4- wnuassas; Y INVENTOR} -M. Z. M. Ben 0mm Mclnneme y Y ALITORNEY B. McINNERNEY.

Patented Jan. 11,1921.

6 SHEETS-SHEEI 5.

INVENTOR M Z M 7 5 Ben/gm}; Mclnnemey B. MclNNERNEY. ELECTROMAGNETIC SWITCH.

APPLICATION FILED 050.20. 19's.

1,364,944. Patented Jan. 11,1921.

6 S'HEETSSHEET 6- WITNESSES: INVENTOR @m&%1/4;4mm/ I 5 70277 Mc/memea UNITED STATES BENJAMIN MCINNERNEY, OF COUNCIL BLUFFS, IOWA.

ELECTRO AGNETIC SWITCH.

specification of Letters Patent. Patented J an. 11, 1921.

Application filed December 20, 1916. Serial No. 138,020.

To all whom it may concern:

Be it known that I, BENJAMIN MoIN- NERNEY, a citizen of the United States, and a resident of Council Bluffs, in the county of lottawattamie and State of Iowa, have invented a new and useful Improvement in Electromagnetic Switches, of which the following is a specification.

My invention relates to elcctromagnetically operable switches and it has'particular relation to switches of the so-called lockout type that operate only under predetermined circuit conditions.

My invention has, for one of its objects, to provide a switch of the above-indicated character that is simple in construction and eificient in operation to close a circuit controlled by it only when the current traversing a magnetizing coil of the switch falls to a predetermined value.

Switches of the same general character as that of my invention have been provided heretofore, but they usually comprised single series actuating coils. Such switches are not well adapted for certain applications because of the relatively short period during which the current-exceeds the predetermined value and because of the rapidity of the changes in current value caused by the operation of switches or the acceleration of the motor, as the case may be. \Vhen a motor is supplied with energy from a source of variable electromotive force, the switches may open in case the electromotive force falls to a relatively low value, and the insertion of the armature resistor tends to decrease the electromotive force applied to the motor rather than to into close theswitch is always available except upon failure of voltage.

In the preferred form of my invention, armaturemembers are actuated respectively by electromagnets energized by the series coil and by the shunt coil. The armature value. If, however, the current traversing the series coil exceeds the predetermined value, the movable switch member is held in its open position, the spring for operatively connecting the armature controlled by the shunt coil to the movable switch member is placed under stress and the switch is closed immediately upon the current falling to the predetermined value.

My invention is adapted for use in connection with the acceleration of electric motors. An electric motor may be started by an, arrangement comprisinga series of switches constructed in' accordance with my invention for successively operating to shunt resistors in the armature circuit of the motor and for inserting a resistor in circuit with the shunt field-magnet winding of a motor. Each of the switches, except the last to close, operates to shunt a portion of the series coil of the succeeding switch to close in order to insure that the switches operate in the proper sequence.

The details of my invention will be de scribed in connection with the accompanying drawings, in which Figure 1 is a side view, partially in elevation and partially in section, of a switch constructed in accordance with my invention. Fig. 2 is a front view, in elevation, of the switch of Fig. 1. Fig. 3 is a side view, in elevation, of a modification of the switch shown in Fig. 1. Fig. 4 is a diagrammatic representation of a system embodying a plurality of switches similar to that shown in Fig. 3 for controlling the circuits of an alternating-current motor. Fig. 5 is a diagrammatic representation of a direct-current system embodying a plurality of switches constructed in accordance with my invention. Fig. 6 is a plan view of a switch of modified form the circuits and apparatus of a system'in connection with which it is employed being diagrammatically shown. Fig. 7 is a side view, in elevation, of the switch shown in Fig. 6.

Referring particularly to Figs. 1 and 2, a base plate 1 of slate, or other suitable material, supports a pair of stationary contact members 2. A pair of coacting movable i switch members 3 are rigidly connected to a the c011 8 is accordingly connectedbetween member 4 that is pivotally supported at 5 by a bracket 6.

A stationar magnetizablc member 7, of substantially -shape, is provided with an energizing coil 8 that is connected in shunt relation to the translating device controlled by the switch. In the present case, the switch is adapted to be employed in connection with alternating-current circuits, and

two of the line conductors.

An armature 9, which is also pivotally supported at 5, is operatively connected to the member 4 by means of a spring 10, a pivotally mounted member 11 and a spring 12. Three series coils 14, which are supported by the magnetizable member 7 are provided with adjustable core members 15 which coact with an armature member 16. As shown in Fig. 2, each of the coils 14 is provided with an intermediate terminal in order that the number of turns may be controlled, for reasons to be later described. The armature member 16 is secured to the pivotally mounted member 11.

While I have shown and described three series coils for preventing the closing of the switch, under predetermined conditions, it is obvious that two of the coils may be omitted, since the current traversing one phase of a three-phase circuit corresponds substantially to that traversing the other circuits. It is immaterial, also,'whether a single shunt coil or a plurality ofsuch-coils is employed for effecting and maintaining the closure of the switch.

It may be assumed that the switch mechanism shown m-Figs. 1 and 2 occupies its openosition. When a line switch, or other suitab ie switch, is closed, the shunt coil 8 is energized and the armature member 9 is attracted to its illustrated position 1 If, for example, the switch is employed inconnection with an electric motor, a rush of current occurs in the motor circuit which includes, in the case of a three-phase motor, each of the series coils 14.

If the coils 14 are energized above a predetermined value, the armature member 16 and the connected mechanism, including the member 4 and the movable switch arms 3, are retained in their respective positions illustrated in Fig. 1. The spring 10 has been placed under tension by the relative movement of the armature 9 and the member 11.

When the currents traversing the circuits comprising the series coils 14 fall to such values that the force of the spring 10 is sufficient to overcome the pulls exerted by the core members 15, the member 11, the member 4 and switch arms 3 are actuated to the closed position of the switch. The coil 8 is energized by a substantially constant force during such time as the line switch is closed.

Reference may now-be had to Fig. 3, in which is illustrated a modification of the switch shown in Figs. 1 and 2. Similar retercnce numerals are em loyed to designate corresponding parts. '1" e operation of the switch shown in Fig. 3 is substantially identical with that of the switches previously described, but certain of the structural details have been modified. A movable switch arm 17 carries two contact members 18 which coact with corresponding stationary contact members 19. The contact members 18 are connected by a flexible shunt conductor to a terminal 20 which may be connected to one phase of a three-phrase circuit to which the members 19 are respectively connected.

The movable arm 17, which is pivotally mounted at 21, is rovided with a projecting member 22. n armature member 23, which is also pivotally supported at 21, is operatively connected to the arm 17 by means of a spring 24, the respective ends of which engage projecting portions of the movable arm 17 and the armature member 23. The projection 22 carries, at its lower end, an adjustable member 25 which constitutes the armature member of an electromagnet comprising a series magnetizing coil 26. The coil 26, which is diagrammatically represented, is provided with an intermediate terminal in order that the numbers of turns may be controlled, as will be later described in connection with the various systems embodying switches constructed in accordance with my invention.

The operation of the switch differs in no material respect from that of the switch previously described. The energization of the shunt coil 8 causes the armature member 23 to exert a force upon the spring 24 tending to close the switch. If the current traversing the series coil 26 is of such value that the force exerted upon the member 25 retains the member 17 in its open position, the spring 24 remains under compression. When the current traversing the coil 26 falls to the predetermined value at which the mechanism is adjusted to operate, the spring 24 effects the actuation of the member 17 to its closed position.

A system for controlling the secondary circuit of a three-phase induction motor and embodying a plurality of switches similar to that shown in F ig. 3, is illustrated in Fig. 4. Similarreference numerals are employed to designate parts corresponding to those of the switch shown in ig. 3. The several switches 27, 28 and 29 are mounted in alinement, a single shaft 30 constituting a pivotal support for the respective switch members 17. The shaft 30 is secured to three arms 31, each of which corresponds to the projecting portion ofthe armature member 23 of the switch of Fig. 3. The shaft 30 is provided with an arm 32 which constitutes the armature member of an electromagnet or solenoid 33. The solenoid 33 is supplied with energy from the line conductors for supplying energy to the primary windings of an electric motor 34.

Each of the

switches

27, 28 and 29 controls a section of each of resistors 35 that are connected in circuit with the secondary windings of the induction motor 34. The

switches are respectively provided with series coils 36, 37 and 38 that are connected in series relation with one of the phase windings of the secondary winding. The coils 37 and 38 are provided with an intermediate terminal that is connected to the preceding switch to close.

It may be assumed that it is desired to start the motor 34. A line switch 38 may be closed to, connect the motor to any suitable source of alternating current. The solenoid 33 is energized to attract the armature member 32 and thereby place the several springs 24 under compression. The forces exerted by the respective springs 24 tend to close the corresponding switches. A heavy rush of current traverses the secondary circuit, however, upon the closing of the line switch 38 ,and the coils 36, 37 and 38 are energized to retain the movable switch members 17 in their open positions.

When the current traversing the secondary circuit falls to a predetermined value, the force exerted by the series coil 36 decreases to such degree that it is less than that exerted by the spring 24 tending to close the switch. The switch 27 then closes to shunt one section of each of the resistors 35, and, at the same time, to shunt a portion of the turns of the series coil 37.

The

switches

28 and 29 do not close simultaneously with the switch 27 for the reason that the coils 37 and 38 are provided with a number of turns in excess of the required number to hold the switch open when the current is above the predetermined value. \Vhen a shunt circuit is established for a portion of the turns of these coils, the remaining turns are equal to the turns of coil 36. This arrangement insures that the switches operate in the propersequence.

A second rush of current traverses the secondary circuit upon the closing of the switch 27, and the switch 28 remains in its open position until the current has again fallen to the predetermined value. In like manner, the switch 28 shunts a section of each of the resistors 35 and shunts a portion of the turns of the series coil 38 in order that the switch 29 may operate when the current again falls to the predetermined value. o

Bymeans of the arrangement described above, a single actuating coil may be-employed for closing a plurality of switches.

This coil is energized upon the closing of the main switch. The operation of the switches in a definite order is insured by providing the lockout coils with an abnormal number of turns that are energized previous to the closing of the preceding switch in the series.

Reference may now be had to the system illustrated in Fig. 5, in which a series of switches constructed in accordance with my invention is employed for controlling the resistance of the armature circuit and of the circuit of the shunt field-magnet winding of a direct-current motor. Line conductors 39 supply current to an electric motor havin an armature indicated at 40 and a shunt fieldmagnet winding 41. Resistors 42, 43 and 44 are respectively controlled by electromag netic switches 45, 46 and 47.

Each of the switches 45, 46 and 47 is provided with an actuating coil 48, the respec tive terminals of which are connected to the line conductors 39. The several switches are provided, also, with coils 49 that are connected in series with the armature winding 40. A portion of each of the series coils of switches'46 and 47 is adapted to be shunt-- ed upon the closing ofthe preceding switch. The additional turns of the series coils are provided in order to insure that the switches close in proper sequence. The shunt coils 48, when energized, tend to eflect the closing of the corresponding switches. The series coils 49 oppose the force of the shunt coils 48 in accordance with the current traversing the armature circuit of the motor.

A shunt circuit for a resistor 50, that is in circuit .with the shunt field-magnet winding 41, is controlled by an electromagnetic switch 51. This switch is provided with a series closing coil 52 and a shunt coil 53 which opposes the force of the coil 52.

When a line switch 54 is closed, a rush of current traverses the armature circuit of the motor which extends from positive line conductor 39, through the several series coils 49, the resistors 42, 43 and 44, series coil 52, and armature 40, to negative line conductor 39. The several shunt actuating coils 48 are energized upon the closing of line switch 54.

The shunt coil 48 of switch 45 tends to close the switch, but this action is prevented by the force of series coil 49 as longv as the current traversing the motor circuit exceeds a predetermined value. When the current falls below the predetermined value, the force exerted by the series coil is less than that of the shunt coil 48, and the switch is closed to complete a shunt circuit forthe resistor 42 which comprises a portion of the series coil 49 of switch 46.

A second rush of current through the motor circuit occurs upon the closing of switch 45, and switch 46 remains in its open position until the current falls below the predetermined value, as in the case of switch 45.

' The closing of switch 47 is effected, in a similar manner, to complete a shunt circuit for the resistor 44 and thus complete the acceleration of the motor. by shunting the starting resistors.

During the above-described acceleration of the motor,.the switch 51 remains in a closed position by reason of the fact that the effective turns of the series coil 52 are such that the force exerted by the coil 52 is materially greater than that of the shunt coil 53. The closing of switch 47 completes a shunt circuit for a portion of the coil 52. When the current. traversing the coil '52 falls to a predetermined value, the shunt coil 53 effects the opening of the switch to insert the resistor 50 in circuit with the field-magnet winding 41. The motor is further accelerated by the resultant weakeningof its field.

members may be mounted upon the outer with the armature winding of the motor.

ends of the several movable arms if such arrangement is necessary or desirable.

The operation of'each of the

switch members

56, 57 58 and 59 i controlled bya series coil 62. x for controlling switch member 56, is provided with an intermediate terminal in order that the number of turns of the several coils maybe varied in a manner previously described in connection with the switches shown in Figs. lto 5, inclusive. The

movable contact members

56, 57, 58 and 59 are electrically connected to each other by means of

members

63 and 64. The stationary contact members 60 are insulated from each other.

Referring particularly to Fig. 6,

line conductors

65 and 66 supply current to a directcurrent electric motor, the armature of which is indicated. at 67; Each of the switch members controls a resistor 68 that is in seritIes 1; ma be assumed that the motor is at rest an that the several switch' members are in their respective open positions, as illus trated in Figs. 6 and 7.

To start the motor, a line switch 69 is closed to complete the motor circuits and to establish a circuit for energizing the shunt coil 61..- The coil 61 energizes a magnetic circuit comprising a pole piece 70 and the several switch members which are adjacent to the pole piece. The force exerted by the positions.

fecting the closing of several switches in Each" of the coils 62, except that magnetic circuit mentioned above tends to effect the closing of all of the switches. When the motor circuit is completed, a heavy rush of current traverses a circuit comprising line conductor 65, armature 67, resistors 68 and coils 62, which areconnected in series and. arranged alternately in the circuit, to the line conductor 66. All of the switch members are accordingly retained in their open When the current traversing the armature circuit falls to a predetermined value, the force tending to. close switch member 56 is greater than that exerted by the corresponding series coil 62, and the switch closes to shunt thecorresponding resistor 68. This shunt circuit includes, also, a portion of the coil 62 for retaining the switch 57 in its open position. A second rush of current occurs upon the closing of switch 56, and switch 57 is held in its open position until the current'again falls to the predetermined value. In a similar manner, the

switches

58 and 59 close in order to shunt the corresponding resistors 68 and thereby accelerate the motor t its normal speed. 7

The arrangement shown in Figs. 6 and 7 is similar to that shown in Fig. 4 in that a single actuating coil is employed for efsequence.- Separate series coils are provided for the several switch members for controllingthe closing of the switches in accordance with the value of the current traversin the circuit controlled by the switches. i switch of the.character just described constitutes a neat and compact device which occupies comparatively "small space and may be manufactured more easily and with greater economy than a corresponding num- 1 her of separate switches for accomplishing the same results.

It will be noted that systems arranged in accordance with those illustrated in Figs. 4. 5 and 6 operate automatically to effect the ac- 1 celeration of electric motors either .of the a ternating-surrent or direct-current type. A substantially constant force is available. at all times, during the acceleration of the motor to effect the closing of each switch. 116 The force opposing that of the closing coil is variable and the switch is closed ractically instantly upon the decrease of t 1e opposing force below a predetermined value. This predetermined value may be varied by 120 adjusting the core members. This arrangement insures that, the switches operate promptly in accordance with the value of the current in the motor circuit.v 'When a single series coil is employed, the actuating 126 force, which is variable, may fall below that required to overcome the inertia of the movable part before the switch is closed.

Switches constructed in accordance with my invention are particularly adapted for use in connection with hoists that operate at high speeds, gearless traction elevators or mine hoists embodying spur gear mechanism. In the above and similar machines, it frequently occurs that the loads operate the motors as generators. In such case, the current traversing the motor circuit decreases so rapidly that series lockout switches could not operate during the brief interval in which the armature current was of sufficient value to effect their closing. By employing actuating coils that are energized independently of the current traversing the motor I circuit, the closing of the switches is insured regardless of whether the motor operates as.

/ a motor or as a generator.

By employing a spring which permits movement of the armature member con- .trolled by the shunt coil relatively to the switch member to which it is operatively connected, the force for closing the switch is a maximum at the beginning of the closing movement. Since the armature member assumes its operative position upon the closing of the circuit of the shunt coil, the spring is placed under maximum stress and its force is available when the opposing force falls below the predetermined value.

In a switch of the usual construction, the closing-force is at a minimum value at the beginning of the movement because of the relatively large air gap between the core member and the armature member of the electromagnet. The closing force increases rapidly as the air gap is decreased, and a considerable shock occurs upon the engagement of the switch members.

I claim as my invention:

1. In an electromagnetically operable switch, the combination with a base, a switch member pivotally mounted thereon, a pair of armature members movable relatively to each other and to said switch member and pivoted upon the'pivot of said switch member, and means for operatively connecting all of said members, of electromagnetic means tending to actuate said armature members for moving said switch member in opposite directions.

2. In an electromagnetically operable switch, the combination with a movable switch member, of means tending to actuate said member in opposite directions, said means comprising an actuating coil and a retaining coil having a normal number of turns and an abnormal number of turns the latter of which are adapted to be rendered ineffective under predetermined conditions.

3. In an electromagnetically operable switch, the combination with a movable switch member, of means tending to actuate said member in opposite directions, said means comprising an actuating coil and a retaining coil having an intermediate connection for rendering a portion of said coil ineffective under predetermined, conditions.

4. In an electromagnetically operable switch, the combination with a movable switch member, of means tending to actuate said member in opposite directions, said means comprising ,an actuating coil and a retaining coil having a normal number of turns and an abnormal number of turns for preventing the operation of said switch under normal operating conditions, said abnormal number of turns being adapted to be shunted under predetermined conditions.

5. The combination with a plurality of movable switch members and a single means for exerting a substantially constant force for effecting the operation of said switch members in one direction, of separate means for opposing the operation of the respective switches, and means for varying theforce of each of said separate means.

6. The combination with a plurality of movable switch members and a single shunt coil for tending to effect the operation of all of said members, of a separate series coil for retaining each of said members in one position. a

7. The combination with a plurality of movable switch members and a single shunt coil for tending to effect the operation of all of said members, of a series coil for retaining each of said members in one position, each of said series coils except that of the first switch to close having a number of turns in excess of those required during normal operation of the switch and that are controlled by the preceding switch to operate.

8. The combination with a plurality of movable switch members and a single shunt coil for tending to effect the operation of all of said members, of a series coil for retaining each of said members in one posi-.

tion, and means comprising a portion of certain of said series coils for insuring the 9. The combination with a base and a stationary contact member and a pivoted contact member supported thereby, of a pair of armatures pivotally mounted upon the pivot of said pivoted contact member, a spring tending to maintain said armatures separated, a spring tending to maintain one of said armatures and said pivoted contact member separated, a shunt coil for actuating said other armature to cause the engagement of said contact members, and a series coil for actuating said one armature to prevent said engagement. v

10. An electromagnetic switch comprising an energizing winding and a magnetic structure therefor, a pivoted switch arm normally in open position and held in closed position by a force set upby said wind ing pivot to hold the switch arm in open position, and a member moved by the energizing winding to set up a force which becomes effective to move the switch member in a closing direction when the current in the holding-out winding drops to a predetermined value.

1].. An electromagnetic switch comprising an energizing winding and a magnetic structure therefor, a pivoted switch arm normally in open position and held in closed positionby a force set up by said winding side of the pivot to set up a constant force which becomes effective to move the switch member in a closing direction when the current in the holding-out winding drops to apredetermined value.

In testimony whereof I have hereunto subscribed my name this 15th day of Dec.

BENJAMIN MCINNERNEY.