US2355909A - Polarized relay - Google Patents

Description

Aug. 15, 1944. E. DICKTEN, JR

. POLARIZED RELAY Filed July 11, 1940 2 Sheets-Sheet 1 FIG! //v VENTOR By E. D/CKTE/V, JR.-

A TTOR/VE 1 Aug. 15, 1944.

E. DIC KTEN, m

POLARIZED RELAY 2 Shets-Sheet 2 Filed July 11, 1940 lNl ENTOR E.D/CK7'EN,JR.'

' ATTORNEY Patented Aug. 15, 1944 POLARIZED RELAY Emil Dickten, J12, Totowa, N. 5., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application July 11, 1940, Serial No. 34 L893 4 Claims.

This invention relates to an electromagnetic device and more particularly to a polarized relay.

It is often desirable in signaling systems to selectively close two work circuits by the operation of a polarized relay in response to the energization of its winding by current of either positive or negative polarity. If a polarized relay of the type which has a single armature biased to a neutral position is used for this type of service, there is always the possibility that if the armature is not accurately biased in the neutral position, it may fail to operate on current of one polarity or may operate falsely due to vibration when the winding is not energized or is energized with a non-operating value of current.

It is therefore the object of the [present invention to provide a relay structure of the polarized type which has three Very definite positions of which two are circuit closing and the third a neutral or open circuit position.

.t is a further object of the invention to provide a polarized relay structure which has a suitable margin of safety against false operation when a high percentage of the operate current is flowing and the relay is at the same time subjected to vibrations.

It is also a further object of the invention to provide a polarized relay structure which is economical to manufacture and which requires a minimum of maintenance.

In accordance with this invention, several modifications of which have oeen disclose-d, these objects have been obtained by the use of the non-linear magnetic characteristic of a section of iron as a magnetic rectifier to admit or impede the flow of magnetic flux according to its polarity. As illustrative, the iron is in the form of a small U-shaped keeper or yoke shortcircuiting a short permanent bar magnet. A high magnetic flux exists in the yoke which is considered to be essentially saturated. Flux from the core of an elctromagnet is fed into the base of the keeper and is directed to either one of two working gaps near the ends of the legs of the keeper. In one leg of the keeper, flux due to the electromagnet opposes the saturating flux set up by the bar magnet, making the sum of the two fluxes less than the saturating value and consequently operating flux reaches the working gap near the end of that leg. In the other leg the electromagnetic flux is in a direction to aid the saturating flux thereby tending to create a flux greater than the saturating flux but since this can produce only a negligible increase, operating flux can reach only one working gap depending on the direction of the operating current.

lwo independent armatures may be used at the two working gaps or a single armature may be provided for cooperation with both gaps.

For a more comprehensive understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 is a top plan view of a two armature relay embodying the invention;

Fig. 2 is a perspective View of a modified form of the invention as applied to a relay of the sealed switch or contact type;

Fig. 3 shows in cross-section, a mercury type switch element applicable to the relay disclosed in Fig. 2;

Fig. 4 shows in cross-section a magnetic type switch element applicable to the relay disclosed in Fig. 2; and

Fig. 5 is a perspective view of a further modified form of the invention having a single threeposition armature.

Referring first to Fig. 1, the invention has been disclosed as applied to a well-known type of relay structure, having a core I, the rear end of which terminates in a flattened portion 2 provided with two oppositely extending ears 3 and 4 by means of which the relay may be secured to a mounting rack. Surrounding the core is an operating coil 5. Welded or other wise secured by its base to the forward end of the core t, beyond the front spoolhead 29 of the coil 5, is a U-shaped iron yoke 6, the legs 1 and 8 of which extend forwardly with their outer or pole faces lying in planes parallel to the flattened portion 2 of the core I. Secured between the ends of the legs of the yoke K5 is a short permanent bar magnet 9 having its north pole in engagement with the inner face of the leg 8 and having its south pole in engagement with the inner face of the leg 1. The yoke 6 serves as a keeper for the magnet 9 and is so proportioned that it is normally essentially saturated by the flux flowing therethrough from the magnet 9.

Disposed on the opposite faces of the flattened portion 2 of the core I are two U-shaped members iii and it having their bases suitably secured thereto as by screws (not shown) and each having the ends of its outwardly extending arms bent oppositely and parallel to the faces of the portion 2 to serve as supports for spring pile-ups and for the reed hinges I2 and I3 of the armatures I 4 and I5. Each armature is substantially U-shaped, the ends of its rearwardly extending legs being hinged to the forward edges of the members III or I I by the reed hinges and its forward cross-reach overlying an outer pole face of the yoke 6. For adjusting the length of the air gaps between the cross-reaches of the armatures and the pole faces of the yoke 6 and for limiting the extent of the movement of the armatures, back-stop studs I5 are secured to the ends of the legs of yoke 6 with back-stop nuts I'I threaded thereon against which the ends of the armatures are normally biased by the contact springs I8 and 2| which engage against the insulating studs 24 carried by the armatures.

Each of the four spring pile-ups, of which two are disclosed, comprises three contact springs and two of the spring pile-ups also include terminal lugs for the coil 5. For example, the lefthand pile-up comprises contact springs I8 and I9 mounted on the inner face of the arm of member I i) and contact spring 20 and terminal lug 25 mounted on the outer face of the arm of member Iil. These springs and the terminal lug are secured to the member II] by screws 26 which extend through holes in the clamping plate 21, the springs and terminal lug, the member I and into tapped holes in the inner clamping plate 28. The springs and the terminal lug are insulated from the clamping plates, from the member ID and from each other by interposed strips of insulating material and from the screws 25 by the usual sleeves of insulating material which surround the screws. The contact springs I9 and 26 are provided with the usual tangs which engage in notches in the front spoolhead 29 for determining the gaps between their contacts and the contacts of spring I8. The pileup including contact springs 2I, 22 and 23 and terminal lug 30 are similarly insulatedly supported on the end of member I I by the clamping plates 3I and 32 and the screws 33. The back contact springs 20 and 23 may, if not required, be omitted.

Can cover guides 34 are secured at their rear ends to the members 90 and H by the same screws which secure the members to the flattened portion 2 of the core with their forward ends engaged against the edges of the front spoolhead 29.

Considering the operation of this relay, the permanent magnet 9 and the yoke 6 are so proportioned that a flux density is normally produced in the yoke, sufficiently large to operate the iron of the yoke in the vicinity of or above the knee of the saturation curve. In this high flux density condition the yoke will still have a low reluctance compared with that of the air-gaps between the pole faces of the yoke and the crossreaches of the armatures I4 and I and thus the yoke 6 sufiiciently shields the armatures magnetically so that there is a negligible initial attractive forc applied to the armatures due to leakage or stray flux from the permanent magnet 8. Neglecting leakage, the permanent magnet fiux may be visualized as leaving the north pole and proceeding around the short-circuiting yoke 6 and entering the magnet at its south pole.

When the coil 5 is energized, a coil flux will be created which will flow through the core I, dividing at its junction with the yoke 6 and will tend to flow through the legs I and 8 of the yoke, thence across the air-gaps and through the armatures I4 and I5 and uniting again at the rear end of the core. The direction of the flow of flux in this divided flux path will, of course, depend upon the direction of the energizing current flowing through the coil 5. If the direction of flux due to current in the coil is visualized as leaving the core and entering the yoke, the coil flux opposes the permanent magnet flux in the direction of the armature I5 and the flux density in the leg 8 of the yoke is therefore decreased and flux readily flows across the air-gap from the leg 8 to the armature I5, whereby the armature I5 is attracted to close the contacts of springs 2| and 22 and to open the contacts between springs 22 and 23. At the same time in the leg 1 of the yoke, the coil flux aids the permanent magnet flux but since this leg is already almost or entirely saturated due to the permanent magnet flux, the increase in flux in this leg will be slight 0r nil and armature I4 will be unaffected. Thus armature I5 will tend to operate while armature I4 remains unoperated.

As the total amount of flux due to the coil 5 approaches that due to the permanent magnet 9, the entire flux will flow through the leg I of the yoke, through the permanent magnet 9, across the air-gap between the leg 8 and armature I5 through the armature back to the core I. This is under the assumption that there is no leakage flux and that the leg I of the yoke on the side of the unoperated armature I4 can carry no more than the initial permanent magnet flux. A current of opposite polarity in the coil 5 will reverse the direction of the coil flux and cause the attraction of armature I4 while armature I5 is unaffected.

It will be noted that the working flux is due to the current passed through the operating coil and the performance is similar to two neutral relays having oppositely poled rectifiers in series with their coils. The function of the permanent magnet 9 is that of a magnetic rectifier, directing working flux to either one of the armature air-gaps depending upon the polarity of the operating current. The sensitivity is thus comparable to that of a neutral relay, the pull on an armature being proportional to the square of the flux in the working gap due to the current in the coil.

In the unoperated condition because of the permanent magnet flux in the yoke, there is a magnetomotive force drop across it. This tends to send flux through the path including both armatures and their air-gaps and to produce some initial force on the armatures. Since the reluctance of the air-gaps is high compared to that of the yoke, even when it is operated at a high density, this flux and hence the initial steady pull on the armatures will be small. This will be true so long as the armatures remain unoperated and the air-gaps are large. When an armature is operated, however, the reluctance of the correspondin air-gap is reduced and, being in parallel with one of the legs of the yoke, it will draw appreciable flux. Thus, the permanent magnet flux through this armature can be made to lock it in the operated position against the back force of the contact springs operated thereby after it has been brought to this position by the operating coil. This locking feature can be easily avoided by the use of armature stop discs of non-magnetic material to prevent too great a reduction of the air-gap reluctance when an armature operates.

Fig. 2 illustrates a further application of the magnetic rectifier principle to a relay of the sealed contact type. This relay comprises a supporting member or heel piece having a rear upturned car 36 by which the relay may be sup ported on a relay mounting rack and two cars 31 upturned from the rear edges of the member 35 for supporting pile-ups of terminal lugs. Each pile-up comprises three T--shaped lugs 38 which serve as terminals to which the terminals of the operating coil 39 and the terminals of the switch elements 40 and 4| may be connected. The terminal lugs of these pile-ups are secured to the outer faces of the ears 3? by screws 42 which extend through holes in the clamping plate 43, in the lugs 38 and into threaded holes in the ears 3?, the lugs being insulated from the cars 31, from the plates 43 and from each other by interposed strips of insulating material and further insulated from the screws 22 by the usual sleeves of insulating material which surround the screws.

The forward end of the supporting member is widened out to form a lower pole-piece 35. Supported on the member 35 intermediate its ends is a vertically extending core on which the coil 30 is positioned and on the upper end of which the member 45 is secured. The member 45 and core may be secured to the member 35 by the screw 45. Secured by its base to the outwardly extending end of member dii by screws is an iron yoke 41, the downwardly extending legs 63 and 49 of which are bent outwardly at right angles to form two upper pole-pieces 5!) and 5! which lie in a plane parallel to the plane of the lower pole-piece M. For maintaining the pole- pieces 50 and 5! properly spaced from the pole-piece 44 and to lend rigidity to the polepieces, a brace 52 of non-magnetic material is interposed between the member 35 and 45. The upper end of the brace is provided with lugs engaged between the shoulders 54 of the member 55 and. the rear edge of the yoke il and the lower end of the brace is provided with lugs 55 which engage in notches in the edges of the member 355 for holding the brace in its assembled position. Suitably secured between the legs 4% and 49 of the yoke M is a permanent bar magnet 55. The yoke i-l' serves as a keeper for magnet 56 and is so proportioned that it is nor mally practically saturated by the flux flowing therethrough from the magnet 5%.

The pole-pieces 5d and 52 are provided with two sea-led switch elements dd and. M.

operable type, two such types suitable for use in the relay structure of Fig. 2 being disclosed in Figs. 3 and 4.

The switch element disclosed in Fig. 3 may be of the type disclosed in the application of H. C. Harrison and C. E. Pollard, Serial No. 302,526, filed November 2 1939, now Patent No. 2.241493. issued July 1, 1941. This element comprises a tubular glass vessel 5'? into the upper and lower ends of which are sealed the terminals 59 and 58. The lower portion of the vessel is filled with a p001 of mercury 69 into which the inner end of the lower terminal 58 extends and upon which an annular iron armature 6! floats. The inner end of the upper terminal 59 extends downwardly inside of the armature 6! to a point just above the surface of the mercury pool. Preferably the vessel 51 is evacuated before it is sealed and is refilled with a gas such as hydrogen. If switch elements of this type are used in the relay assembly of Fig. 2, they are so positioned in the aligned holes in the pole-pieces thereof that the lower ends of their armatures 6| are positioned above the lower pole-piece M as disclosed in Fig. 3.

This relay, if provided with switch elements of the type just described, functions in much the same manner as described in connection with the operation of the relay of Fig. 1 in that normally permanent magnet flux flows through the yoke 41 and operating flux due to energizing the coil will tend to flow from the pole-piece 5i! to the pole piece M across the air-gaps between the armature 5i and the pole-pieces to operate the armature 6i downwardly against the surface tension of the mercury and to thereby displace the mercury upwardly into engagement with the upper terminal 59 to interconnect the terminals 58 and 59 through the mercury if current flows in one direction through the coil 3% or to cause coil flux to flow from the pole-piece Ad to the pole-piece 3! to similarly operate the armature of the switch element 4| to interconnect its terminals if current flows in the reverse direction through the coil.

The switch elements 45 and ll may be of the type disclosed in the application, Serial No. 198,629 of W. B. Ellwood, filed March 29, 1938, now Patent No. 2,289,830, issued July 14, 1942. This switch element, disclosed in Fig. 4, comprises a glass vessel 6'2 into the upper and lower ends of which are sealed terminals 64 and 63 to the inner ends of which are welded reeds 66 and S5 of magnetic material. The overlapping ends of these reeds are normally out of engagement and may be provided with contact surfaces of any suitable metal having good electrical conductivity. The vessel is evacuated before it is sealed and is refilled with a gas such as helium. If switch elements of this type are used in the relay assembly of Fig. 2, they are so positioned in aligned holes in the pole-pieces thereof that the gaps between the ends of the reeds 65 and 555 are central. located with respect to the upper and lower pole-pieces as disclosed in Fig. 4.

H flow from the pole-piece 59 to the pole-piece M across the air-gap between the reed E55 and pole-- piece 58 across the air-gap between reeds 535 and '65 and across the air-gap between the reed t5 and the pole-piece 4t and the reeds will be tracted toward each other into contact engagement if current flows in one direction through the coil 35) or to cause flux to flow from polopiece 55 to the pole-piece M to sim larly operate the reeds of the switch element M into engagement if current flows the reverse direction through the coil.

5 discloses the magnetic rectifier principle app-lied to a relay structure has g a single armature. In accordance with this modification. a heel-piece 6'! is provided by means of which th relay be secured. to a mounting rack. A core d8 extends forwardly at ri ht angle from th heel-piece having a coil 59 thereon and hav ing an iron yoke 1E5 se ured its base to the forward end of the core beyond the front spoolhead of the coil 59. The legs H and '52 of the yoke extend upwardly to a mint above the coil 59 and are provided on their inside surfaces with pole blocks l3 and M welded or otherwise secured thereto. ecured between the legs TI and T2 of the yoke is a permanent bar magnet 15. The yoke serves as a keeper for the permanent magnet and is so proportioned that it is normally essentially saturated by the flux flowing therethrough from the magnet.

The heeliece 81 is provided with a tongue 16 extending forwardly over the top of the coil 69 which serves as a support for two spring pileups and for the reed hinge 1! of the armature 18. One spring pile-up, comprising the contact springs 19 and 80 and the coil terminal lug 8!, is secured on one face of the tongue 18 by screws 82 and clamping plate 83, the springs and terminal lug being insulated from each other, from the tongue 16 and from the clamping plate 83 by interposed strips of insulating material and insulated. from the screws 82 by the usual sleeves of insulating material which surround the screws. The other spring pile-up comprising the contact springs 84 and 85 and the coil terminal lug 86 are similarly secured on the other face of the tongue 16. The pairs of contact springs 79 and 83, and 84 and 85 normally have their contacts out of engagement. The armature '18 is hinged at its rear end by reed spring H to the tongue 16 of the heel-piece 67 and has its forward or free end positioned between the pole blocks 13 and M. The end of the armature is held in a neutral or mid-position between the faces of the pole blocks by the inside springs 88 and 54 which are biased against the ends of the stud 8? of insulating material extending through the armature.

The operation of this relay is much the same as that of the double armature relay cf Fig. 1. The locking characteristic previousl described is of special importance, however. Some of the permanent magnet flux will pass across the ends of the legs H and T2 of the yoke through the pole blocks 13 and 14 and through the end of the armature and will cause locking forces to act on the armature. With the armature biased in the mid-position, these locking forces are balanced, the armature is in unstable equilibrium, and the relay has a sensitivity to low coil or operating currents comparable to that of the usual type of polarized relay. On high operating currents, however, the operating flux in the gaps is large compared to the permanent magnet flux in the gaps and the relay assumes the square loss characteristic of a neutral relay.

From the foregoing discussion it will be apparent that a relay structure, which may take the forms illustrated and described or similar forms, has been devised which permits simple, compact and inexpensive mechanical construction since only a small bar magnet and a small yoke or keeper is required to direct operating flux to either on of two working gaps; that a relay structure is provided which produces a pull on the armature which is essentially proportional to the square of the operating current, thus 1 ermitting easy adjustment when close operate and non-operate requirements must be met and whereby a small change in current produces a large change in pull compared with the usual polarized relay having a pull directly proportional to the operating current; that a relay structure is provided which is not subject to false operation even on excess current and that the provision of a permanent magnet with a keeper produces an ideal magnetic condition in which the permanent magnet has no tendency to demagnetize and thus destroy the efficiency of the relay.

While permanent magnets have been disclosed bridged across the legs of the yokes 6, 41 and 10 of the relays disclosed in Figs. 1, 2 and 5, it is to be observed that such magnets could be replaced by electromagnets so designed as to supply saturating flux to the yokes.

What is claimed is:

1. In a magnetic structure, a heel-piece, a core secured thereto, a U-shaped member made wholly of magnetic material secured by its base directly to one end of said core, a permanent bar magnet interconnecting the legs of said member and wholly within the boundaries of said member, two armatures hinged to said heel-piece with their free ends in cooperative relationship with the two legs of said member respectively, back stops for adjusting the normal air-gaps between said armatures and the pole faces of said legs. springs supported by said heel-piece and associated respectively with said armatures, serving to normally maintain said armatures against their back stops and a coil on said core energizable to cause the selective operation of said armatures dependent upon the polarity of current applied to said coil.

2. In a magnetic structure, a core, an electromagnetic member connected to said core, a pair of armatures, each of which forms an operating magnetic circuit with said core and electromagnetic member, a coil on said core energizable by current in either direction for producing an operating flux in said core, and a permanent magnet forming a closed magnetic circuit with said electromagnetic member and serving to maintain said member in a state of substantial saturation for the purpose of directing the operating flux in said core to one or the other of said armatures to cause the selective operation thereof in accordance with the direction of current flow in said coil.

3. In a magnetic structure, a core, an electromagnetic member connected to said core, a pair of armatures, each of which forms an operating mangetic circuit with said core and electromagnetic member, a coil on said core energizable by current in either direction for producing an operating flux in said core, and a permanent bar magnet forming a closed magnetic circuit with said electromagnetic member and serving to maintain said member in a state of substantial saturation for the purpose of directing operating flux in said core to one or the other of said armatures to cause the selective operation thereof in accordance with the direction of current flow in said coil.

4. In a magnetic structure, a core, an electromagnetic memher connected to said core, an armature forming an operating magnetic circuit with said core and electromagnetic member, a coil on said core energizable by current in either direction for producing an operating flux in said core and a permanent magnet forming a closed magnetic circuit with said electromagnetic member and serving to maintain said member in a state of substantial saturation for the purpose of directing the operating flux in said core to said armature to cause the operation thereof in. accordance with the direction of current flow in said coil,

EMIL DICKTEN, JR.

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