US2108775A - Relay - Google Patents

Description

Feb. 15, 1938. v W D MACGEORGE 2,108,775

RELAY Filed Oct. 8, 1955 345g A p6 W NVENTGR Patented Feb. 15, 1938 UNITED STATES PATENT OFFICE RELAY Sylvania v 'Application october s, 1935, Serin No. 44,014

Claims.

This invention relates to' relays, and particularly to differential relays'for alternating current circuits. y

Relays as developed in the past arranged to respond to small alternating currents have been possessed of disadvantages in that the return to neutral position has been sought by the use of springs or gravity or the like, with most unstable results.

It is among the objects of thisinvention; to improve relay constructions generally; to provide a relay for small current conditions with a predetermined neutral setting which is obtained Without the exercise of any but electrical forces; to provide a differential relay with a coil in series with a source of alternating current to move an armature to a neutral position when another coil in series with the iirst is deenergized; to provide a relay which is statically and electrically balanced; to provide a relay arranged to respond to a small alternating current to control a circuit and arranged to respond to a second alternating current circuit in phase with the first to actuate the relay to vertical or centered position; and many other objects and advantages will become more apparent as the description proceeds.

In the accompanying drawing forming part of this description;

Fig. 1 represents a diagrammatic plan of a relay constructed in accordance with the preferred form thereof;

Fig. 2 represents a similar diagrammatic plan of the preferred form of relay in a circuit With a Wheatstone bridge circuit and arranged to actuate the relay in accordance with the unbalancing of the bridge.

While the preferred form of relay will be shown as possessed of two opposed deviating or diverting coils in addition to the neutralizing coil, it will be understood that but one need be used, or that two may be used in series.

As the relay has many points of use, it will first be described as the unit to be incorporated in any desired circuits, and quite independent of a given circuit, in contrast to the combination shown in Fig. 2.

Referring to Fig. 1, any suitable support, as the panel III may be provided, having a pivot point II, upon which the lever I2 is pivoted, and preferably having on one side of the pivot II the contact element I3, disposed between the opposed contacts I4 and I5, having connectors respectively I6 and il, each forming one contact of independent circuits, the other contact of each of which is the common lead I8, connected to contact I3 through the lever I2 in such manner as to impose no strain, torque, or other resistance to movement, of the lever I2. In this connection it will be clear that connector or lead I8 might be electrically connected through the pivot II if desired. It will be understood, of course, that connectors I6 and i8 are in one circuit, say for instance (and purely illustratively) in a circuit with one iield of a reversible motor (not shown), While connectors II and I8 are in another circuit, say the opposite field of such reversible motor.

The lever I2 has operatively associated with it an armature or solenoid core or bar 20 carried by the preferably insulated and at least :nonmagnetic bracket 2|, usually, but obviously not necessarily, on the opposite side of said pivot II from the contacts I3, I4 and I5. A centering and polarizing coil.22 is disposed about the armature bar or core 2U having its ends connected to terminals 23 and 24, for attachment to a suitable source of electrical energy. Preferably the source is alternating current although direct current can obviously be used to effect the same centering function as later recited, and the coil and armature arrangement is such that generation of alternating current magnetic flux in the centering coil 22 moves the solenoid core to centered relation, if the latter is free to move, and also maintains the armature in centered relation in the coil, with a consequent maintenance of the contact I3 in equally spaced relation relative to contact Il and contact I5. .Obviously during existence of this positioned condition of the lever and contacts, neither circuit I6 and I8 or IT and I8 is closed. Obviously energization of coil 22 by alternating current instantaneously polarizes the ends 40 and 4I of armature 20, with polarity which reverses with the alternations of current.

Suitably supported on the panel or the like III, preferably in axial alignment with the solenoid core or armature 20, is a deviating or energizing coil 25, having at one end a terminal or connector 26, and at the other end a similar connector 2'I, which may be directly coupled to a suitable source of current to be described, or may lead to another auxiliary or amplifying diverting or energizing coil 28, at theopposite end of the armature or core 20, which is wound oppositely from coil 25, and terminates in connectors or terminals 30 and 39. Coil 2-8 obviously might have separate connectors and be in a separate Qilfllit 1mm coil 25, and this is contemplated, as

shown in Fig. 1. It is to be understood that it is not necessary always to provide two coils, as a single coil can perform adequately in certain connections, but two coils in the same circuit amplify the push-pull effect on the armature. It is preferred that coil 25 (and coil 28 if provided) be connected with a suitable current source or independent sources of variable strength, preferably alternating current, Varying from no potential to a plus or minus of small or great strength or amplitude according to demands.

Referring to Fig. 2, the same relay structure as just described relative to Fig. 1, will be observed, as will the diagrammatic showing of a Wheatstone bridge circuit, as the illustrative source of the fluctuations in the operating coil of the relay. Assume one lead I9, of a power line of alternating current comprised of lines 29 and I9, in which line connectors 23 and 24 of the neutralizing or centering coil 22, are placed so that a continuous flow of alternating current through coil 22 is insured, and, which is of.

great importance also, so that the circuit through coil 22 is exactly in phase with the alternating current selectively energizing the coll 25 (and/or 28), as will be described. Lead wire I9 leads to one end of the bridge circuit comprised of arms 33 and 34 on one side, having the tap-off lead 35, and arms 36 and 31 on the other side, and having the tap-off lead 38.

In the preferred form of invention, as shown in Fig. 2, the tap-off leads 35 and 38, are respectively joined with connectors 26 and 30, (with the opposite leads 21 and 39 joined) and the elements or legs 33 and 34, and 36 and 31 of the bridge are in balance so that the alternating current impressed by leads I9 and 29 is balanced on each side of the bridge. It will be clear that at that time alternating current will be flowing in coil 22 so that the alternating current magnetic flux is effective to center the core 20 and thus to maintain the contact I3 out of engagement with either contact I4 or I5 of the secondary circuits, as there will be no current whatever impressed between bridge tap-off leads 35 and 38, and therefore coils 25 and 28 will not be energized.

It may be assumed that the Wheatstone bridge circuit is one in which the resistance in one leg is varied in accordance with variations in condition, which condition is susceptible to change in accordance with controlling motion of the reversible motor illustratively mentioned as having fields in the secondary circuits controlled by contacts I3, I4 and I5. Illustratively the condition might be temperature and the balanced condition of the bridge might be a desired temperature condition.. while temperature fluctuations either way would have corresponding resistance variations and would therefore cause the impressing of a positive or negative current condition between tap-off leads 35 and 38 which would therefore impress a positive or negative current flow between leads or connectors 26 and 30 through deviating coils 25 and 28.

While the same alternating current flow maintains through the neutralizing or centering coil 22, in which the ends 40 and 4I, of core 20, would be alternately polarized in accordance with the phase of the alternating current feeding the coil, it may be'assumed that instantaneously, for

purposes of description only, core end 40 will be N While core end 4I, is, 0f course, S,

43 vof S polarity. It will be evident that as' the end of core 2U, at 40 is instantaneously N, as is the adjacent end. 42 of coil 25, there will be mutual repulsion so that core 20 is pushed away from coil 25 about pivot II, and relay or secondary circuit contact I3 engages fixed contact I4 to complete a secondary circuit. This action carr be had, of course, from coil 25 alone.

Obviously, with coils 25 and 28 in series, but

reversed, the instantaneous value or polarity of i end 44 of coil 28 adjacent end 4I of core 20 with its instantaneous S polarity, will be N, so as to attract core 20 toward itself, and thus to amplify the urge of the relay out of its centered position about pivot II, as will be obvious. As

the instant polarity of core 20 shifts due to alternations of the current in coil 22, the instant polarity of the respective ends of coils 25 and 28 will shift in phase so that the resultant urge on core 20 is the same. of the relay there will be no disturbing vibration, torque, or urge effective on the relay at the time of alternation of polarity of core ends 48 and 4I, as'the coils 25 and 28 are in phase therewith. The centering and actuating or deviating currents must be in phase when alternating current is used to secure a good rm non-chattering contact. 'I'his is important.

Owing to the balance Assuming that the closing of circuit la-u as just described has effected a change of condition through running such motor (not shown). and that responsive thereto the unbalance of the bridge is corrected and balance thereof is restored, then the current flowing through coils 25 and 28 will stop, and the continuing energization of coil 22 will be effective on solenoid core 28 to center same and moving about pivot II to move contact I3 away from xed contact I4 and to break the secondary circuit therethrough, but Without permitting contact I3 to touch opposite contact I5 of the other secondary circuit.

Obviously a change of resistance of the bridge legs so as to cause a negative flow through coils 25 and 28, would instantaneously find end 42 of coil 25 of "S polarity when the instantaneous polarity of end 40 of core 2U was N", so that core 20 would be attracted toward coil 25, to swing contact I3 against contact I5, to close the secondary circuit thus controlled by those contacts. Obviously also, the instantaneous value of end 44 of coil 28 would be S so as to repulse the S pole of end 4I of the core.

While many uses will occur to those skilled in the art, other than as disclosed, as for instance in any desired situation where coil 25 (and 28 if provided) may be subjected to direct current,

while the centering coil 22 is subjected either to alternating current or direct current, certain uses may be pointed out, as follows:

Situations in which the relay will be available in other circuits in mechanical and electrical assemblies will doubtless occur to those skilled in the art, but mention must be made of a selected few of such uses that have occurred to Ame in the connection and which may be listed as follows:

a. Alternating current or direct current Wheatstone bridge circuits in accordance with the instant disclosure.

b; Photoelectric bridge in comparison of colors or light intensities in which the deviating coils may be energized positively or negatively in accordance with the departure from a given value of photoelectric devices (not shown) in their circuits.

c. Approximate time delay relay. In this situation a variable constantan rheostat controls the circuit through one deviating coil while a fixed nickel resistor arranged to operate at a high temperature (not shown) controls a flow through the other deviating coil. If the resistances are initially the same when the current is turned on the relay will be balanced until the nickel resistor heats up sufilciently so as to increase the strength of current owing through the second mentioned deviating coil to close one circuit of the relay. By adjusting thc variable constantan rheostat the length of time required to close the relay can be varied.

d. Under voltage under current relay. In this application a current proportionate to the line voltage passes to one deviating coil while a current proportionate to the line current passes to the other or secondary deviating coil. If an excess vof current passes through the line the attraction of the secondary deviating coil will exceed that of the primary deviating coil and` the relay will act. AConversely if the voltage in the line falls below normal the relay will also act.

e. Reverse current relay. A current transformer (not shown) is in series with a primary deviating coil, while the secondary deviating coil and the centering or neutralizing coil are both excited from a potential transformer having constant voltage characteristics.

f. Speed 'synchronizen Two detached direct current magnetos (not shown) are respectively coupled in driven relation to the equipment to be synchronized, and produce voltages proportional to the speed of their drivers, and which respective voltages are impressed upon the respective opposite deviating coils of the relay. When the speeds are identical the relay will hold and be held in its neutral position. Any variation in relative speed of the respective equipments will r actuate the relay and actuate indicator or control equipment.

q. Polarized alternating current or direct current relay. In this use the centering coil ,is energized from a source having characteristics similar to the actuating source and the relay will operate in accordance with the polarity of the actuating source.

The absence of mechanical agencies to actuate or return the relay partsI to neutral will be appreciated, as will the fact that the relay thus provided is susceptible to extremely minute or weak currents to exert its proper relay function.

I claim:

l. A differential relay comprising a deviating coil having an axis, an armature core, means mounting the armature core for guided movement, the core disposed adjacent to said coil substantially concentric with the axis thereof, a polarizing and centering coil relative to which the core has movement and disposed sc that the core is in its iield, and the core and centering coil acting together as a solenoid, circuit controlling means operatively associated with the armature core.

2. A differential relay comprising a support, a deviating coil mounted iixedly on the support, an armature core, means mounting the armature core for guided movement relative to the support, the core disposed in such proximity to said coil as to be within the magnetic field thereof, a centering coil fixed relative to the support in such proximity to the core as to be witihn the magnetic eld thereof and relative to which the core has guided movement, the centering coil and core'acting together as a solenoid, circuit controlling means operatively associated with the core.

3. A difierential relay comprising a support, a lever, means pivotally mounting the lever on the support in static balance, an armature core mounted on the lever for movement therewith, a centering coil mounted xedly on the support in position to loosely embrace the core and to exert a solenoid centering action thereon, a deviating coil iixedly mounted on the support adjacent to the core with its axis substantially concentric with the core and with the core within the magnetic eld of the deviating coil, circuit co-ntrolling means operatively associated with the lever.

4. A differential relay comprising a support, a lever, means pivotally mounting the lever on the support, an armature core mounted on the lever, a centering coil xed on the support and loosely embracing the core and forming with the core a solenoid to center the core and` hold the lever in a predetermined angular position relative to the pivotal mounting, a deviating coil mounted on the support adjacent to one end of the core in substantially concentric relation to the core so as to urge the core out of its centered position in the centering coil when suitably energized, a second deviating coil Afixedly mounted on the support adjacent to the other end of the core in substantially concentric relation to the core so as to urge the core out of its centered position in the centering coil when suitably energized, electrical connecting means joining the deviating coils in series but in reversed relation so that each augments the urge of the other on the core.

5. In a relay, an armature having a neutral position and a circuit closing position, circuit controlling means operatively associated with the armature, means supporting the armature for guided movement between neutral and circuit closing position, a hollow fixed polarizing and centering coil adjacent to said armature, a core mounted on the armature and disposed within the coil and in neutral position, a deviating coil fixed relative to the centering coil adjacent to said core whereby its magnetic lflux is effective on said core to move the armature to circuit making position.-

6. In combination, a source of A. C., a fixed polarizing and centering coil continuously in circuit with said source, a fixed deviating coil in circuit with'said source, an armature including a core, said core disposed within and forming with the centering coil a solenoid, said core being disposed within the magnetic field of said deviating coil, means mounting the core for guided movement between its solenoid position and a modication thereof incident to energization of the deviating coil, means for energizing the deviating coil with A. C. current of selected polarity instantaneously identical with or exactly opposite to that flowing inthe centering coil so that their zero points occur at the saine instant, and circuitl controlling means controlled by said armature.

7. In combination with a source of alternating current, a relay comprising an armature core, means mounting the core for limited guided movement, a centering coil loosely embracing and lxed relative to said core and forming with said core a solenoid, a deviating coil fixed relative and adjacent to said core and centering coil and having an axis substantially concentric to said core, means including connections between said source and said centering coil and deviating coil Awhereby the centering coil is continuously energized with said alternating current and the deviating coil is arranged for energization with alternating current of selected potential in exact phase with that of the centering coil although selectively of the same or opposite direction whereby lthe deviating coll exerts attraction or repulsion on said core, and circuit controlling means operated by said armature core.

8. A differential relay comprising a support, a lever arm, means mounting the lever arm for pivoted movement relative to said support, a core, a centering coil fixed to the support and loosely embracing said core, a yoke having spaced legs engaging the core on opposite sides of said centering coil and mounted on said lever arm to permit limited substantially 'axial movement of the core in the centering coll by movement of said lever about its pivot, and a deviating coil mounted on the support adjacent to and substantially concentric with the core beyond the yoke.

aftosa/7s the core in the centering coil by movement oi said lever about its pivot, a pair of deviating coils spaced apart and fixed to the support and each substantially concentric with and adjacent to the core on opposite sides oi the yoke.

i0. A dierential relay comprising a support, a lever arm, means mounting the lever arm for pivoted movement relative to said support, a core, a centering coil fixed to the support and loosely embraclngsaid core, a yoke having spaced legs engagingthe core on opposite sides of said centering coil and mounted on said lever arm to permit limited substantially axial movement of the core in the centering coil by movement oi said lever about its pivot, a pair of devia-ting coils spaced apart and xed to the support and each substantially concentric with and adjacent to the core on opposite sides of the yoke, and connecm tions joining the deviating coils in series in re versed directions so that with a current iiowing through both coils the instantaneous polarity of the end o one coil adjacent to one end of the core is opposite to that of the end ci the other coil adjacent to the other end of the core so that the deviating coilsr supplement each other.

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