US2536244A - Spring holder for permanent magnets - Google Patents

Description

lhwcntor JEWILLING AND G.E.DUFF( 5r.

Gttorncu J. E. WILLING ET AL SPRING HOLDER FOR PERMANENT MAGNETS 0r1g1na1 Flled Sept 27, 1946 23 2a 26 L53 3e 3 Jan. 2, 1951 FIG. 3.

Patented Jan. 2, 1951 SPRING HOLDER FOR PERMANENT MAGNETS Joseph E. Willing and George E. Duffy, Sr., Rochester, N. Y., assignors to General Railway Signal Company, Rochester, N. Y.

Original application September 27, 1946, Serial No. 699,678, now Patent No. 2,502,811, dated April 4, 1950. Divided and this application October 26, 1949, Serial No. 123,618

2 Claims. 1 This invention relates to direct current relays, and it more particularly pertains to relays of the biased polar type which have armatures actuated only in response to a particular polarity of energization of the relay windings.

A relay of this character is disclosed in the prior application of G. E. Duffy, Sr., Ser. No. 542,203, filed June 26, 1944, now Pat. No. 2,414,583, dated January 21, 1947. Although a relay of this character has many applications in railway signalling practice, it is often used in polarized circuits in Which its windings are subject to energization of the reverse polarity from that to which it is responsive. It is desirable to provide a structure in the biased polar relay that will prevent relay operation on reverse current, even if the reverse current is provided by an extraneous source of energy at a voltage many times greater than the normal operating voltage of the relay. Protection against the operation of the relay by reverse current is provided as disclosed in the above-mentioned patent by use of a leakage strip forming a shunt across the magnetic circuit including the relay armature in combination with a permanent magnet for substantially saturating the shunt under normal operating conditions.

' This application is a division of our prior application, Ser.No. 699,678, filed September 27, 1946, now Patent No. 2,502,811, dated April 4, 1950, wherein a polar relay of this type was disclosed as having its extent of protection against operation on reverse current increased by the provision of a slotted leakage strip. This feature of providing a leakage strip of reduced cross-section at a point between the poles of an electromagnet was disclosed and claimed in such parent application; and no claim is intended to be made herein to such characteristic features. The present disclosure is more particularly directed to solving the structural problems involved in the use of permanent magnets in such a relay.

One 'object of the present invention is to provide a convenient and'economical means for securing the permanent magnets across the cores of an electromagnet.

Other objects, purposes, and characeristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

r In describing the invention in detail, reference is made to the accompanying drawings in which corresponding reference characters identify corresponding or similar parts of difierent views, and in which-- Fig. 1 is an elevational View of a plug board mounting relay constructed according to the present invention with certain parts shown in cross section as taken along the section line l-i of Fig. 2;

Fig. 2 is a right-hand end View of the relay as shown in Fig. 1; and

Fig. 3 is a view in perspective showing certain of the relay elements in an expanded relationship.

It is to be understood that the application of the present invention to relays of the character disclosed in Fig. 1 is merely typical of the manner in which the present invention may be applied to other types of relays, such, for example, as to the structures of relays having diiierent arrangements of contacts and diiierent types of core and armature structures.

With reference to Fig. l, the relay RI is of the quickly detachable plug board mounting type of the general character disclosed, for example, in the patent to J. F. Merkel, Pat. No. 2,258,123, dated October 7, 1941, to which reference can be made for a more complete disclosure, particularly as to the manner of adjustment of the restoration spring for the relay armature, and as to other features of the relay common to that disclosure and the relay as shown in Fig. 1.

The relay as shown in Fig. 1 comprises a base member 10, preferably molded of insulating material, in which is suitably secured a contact block II also of insulating material having suitably secured therein front contact fingers l2, back contact fingers l3 and movable contact fingers 14, such contacts being electrically connected to the contact tips which extend to the right of the contact block I l for engagement with plug contacts of a suitable plug board (not shown).

The relay BI is adapted by the tubular member 16 for mounting over rods of a plug board (not shown), such tubular members being suitably secured in the base member ill and extending through Openings in the cover H, such cover being preferably of transparent material, and

being secured over the relay to protect its contacts and operating mechanism from dust and mechanical damage. The brackets [9 are threaded on to the left-hand ends of the tubular members IE to secure the cover I! tightly in place.

Abracket 20 of non-magnetic material has pole faces 21 and 22 of magnetic material, such, for example, as silicon steel, suitably secured thereto as by the non-magnetic rivets 23 which protrude slightly to serve as minimum residual pin spacers to provide a minimum air gap of approximately ten thousandths of an inch between the armature 44' and the pole faces 2| and 22 when the armature is picked up.

The pole faces 2! and 22 are suitably secured to the respective cores 24 and 25 as by the screws 26.

The cores 2 3 and 25 have flat'finished sides formed thereon at their left-hand ends at the points 27 for making contact with the permanent 1 magnets PM% and PM2 which aresecurely=-he 1d against the finished surfaces 21 on the opposite sides of the cores 24 and 25-by the spring 3il-=of Phosphor bronze or other suitable spring'material,

such material being preferably nch-magnetic.

The U-shaped spring 30 having somewhat-curved sides 62 not only holds the magnets PM! and PMZ tightly against the cores 24 and 25, but it also holds the magnets in alignment because of its Width being substantially equal"to the spacing between the cores 2 i and25,and because of the sidesof the spring engaging a recessed portion 3! f the magnet PMlhaving shoulder 63;and a similar portion of magnet PM2 (not shown)' to hold'the magnetsPMl and PMZ iii-vertical alignment.

The-leakage strip L is'shown asbeingsubstantially rectangular in shape and of asubstantial thickness, the thickness being dependent upon therelative' size of the corestructure with which it "cooperates. The leakage' strip "L has semicircular-recesses32 fo'rmedthereinof a radius to 'confornito the radius'of the cylindrical portion of thecores' 2t and '25; such recesses" being spaced from each" other by a distance comparable to the spacing-of the coresZd and 25so that the leakage strip L will fit tightly, when positioned as-shown inFigfi3, b'etweenthe cores 24 and-25. By this arrangem ent-a magnetic circuit-of relatively low reluctance can be established through the cores =24" and-25 'in series with the leakage strip L. PIt is-tobeunderstood-that othermeans maybe em- 'ployed for securing the leakage stripacross the cores in accordancewith""thej requirements of practice, such, for 1 example," as using-two "leakage strips'and clamping th'em on'oppositesides of the cores iaS the permanent magnets are clamped.

' In anintermediatep osition'in the leakage strip L, there is ai-eduction in the cross'section of such leakage strip for purposesto-be hereinafter pointed out whenconsideringthe mode of'operation'of the relay. One formof" reduced cross section is illustrated "in Fig. 3, in: which'a "slot 33 l is formed in the leakage strip transverseto the lines of flux. Although the slot 33"is*effe'ctive invarious degrees" 1 in accordance with "its depth, it "has been found in practice that a depth substantiallytwo thirds of the thickness of thefleakage strip L *is sati'sfactory' for providing thedesired mode 'of operation. "Although' diii'erent width 'slo-tsmay be employed has-been foundtdbe desirable that the "slot be maintained atas' narrow a width as possible 'in order-to provide "the most -desired-mode "of operation of the'xrelay. -A slot one thirty-second of an inchin width-has been found to be'satisfactoryY'The leakage strip is fitted between the cores '24 and 25 at apoint adjacent-the" permanent magnets PMl and-*PMZ, with the slot 33 adjacent the permanent magnets 'as-"a" meansjforstandardizing the construction and arrangement "of parts of the' relay; although 'itis to be uri'derstoodthatthe chara'cteristics of the-relay wculd be modified-=only slightly if *the -leakage= strip -L -were spaceda"-shdrt -distance I from the permanent magnets, or if the leakage suitable spools with spacers 36 of insulating material formedmn the ends thereof, such spools being'fitted'o'ver the respective cores 24 and 25 at theright of the leakage strip L.

ZThe cOntact tipsafil make connections to the "respective ends"of the relay winding 34 by extending-throu'gh a-sleeve 38 formed of insulating ;material tothewire connections at the respective endsof the winding 36. -.Fig; mere provided for coupling the wiring con- Similarly, tips 39 (see nections for the Winding 35 to a suitable plug 54 operates the-pusher ffiavertically to selectiveboard (not shown) The cores 24 and '25 are suitably assembled to the base member I0 and to the yoke 43 bridging theends of'the -cores- 24--a1id"-25 as bybdlts flfl threaded intothe-ends of the-*"respective cores armors. "The heads of-suchbo'lts are recessed into the base'lil and a registration plate t] -('see Fig. 2) is secured'o-ver' the 'h'eads of the' bblts-Wl), such-"registration" plate having *holes 42' 'formed therein at positions characteristicof this {type ofre'lay to match-with the pos'itions'of suitable registration pins (not'shoWn) ina suitable plug board (not shown) The spring-washers -fifl take up what end play there'may be in the parts thus assembled. It is'-preferablethat theiyoke fl be permanently" secured across the ends of the es 24 and 25as by=welding toinsure-. aga'inst the omission of that part if for any reason "the relay is later disassembled; i

"The armature-4 4 of suitable-magnetic material such, for example as silicon 'steel, -"is-iof-" an i;- shaped; structure and is positioned by the 'bearing p1ate 45 which fitsdoosly into 5 the sloifit ifi formed in the armature 56. "The armature -plate 41 retains the=bearingiplate i5 within the @6. The armature i i isbiased-to a restore or dropped --'a-\vay position: by' the -biasing -sprinjg to anextent limited "-by the -a'ldju'stment screw iQ ating upon the non magnetic" bracket B at the point 50. The adjustment of the spring fl is accomplished by the thumb nut-'5 latvh-ichis locked in 5 its-' adjusted- '--po'sition-'by" the pin 52, The residual "screw '53 of non magne'tic' inat ial is adjustable to1imit the degree ofattraction of the armature M to-the pol faces- 2 hand-WE In accordance a with the actuatioh off -the armature 44 te its attracted 'or restore'dpositions, the lever ly close front and iback -conta'cts in accoidance with the pickingup I and the restoration respectively of the armature 4. Although ---various ty pes' 0f material 'may be used for: ther-magne'tic circuits of the -relay RI it has been foundthat silicon steel' pro'vi'des satisfactory operation-when em iol'oyedz ast-he material forthe cores 4 1 and 25, ithe' leakage strip -L, the armature and 1 the yoke 'n, 1 It u's desirable because of-"the con'ditions "of: reverse current energization of the relay Rl that the permanent magnets be bf'ai'materiaLrequiring a high coercive'force-tor demagrietization suchf for example; has an' aluminum nickel-cob'alt=iren alloy; Because trams-'- -haid-ness ofsuch materi-al the means heretofore described fon'sec-uring' the magnets 'PMl and l' lifi -to the cores fland fi, without the use of bolts; is highly desirable;

5 'It' is to-"beunderstood thafithmbd-bf operation-"of the"relay'-Rl corresponds=substaritiaily to the mode of operation as set'fdith iii the ab'ove mentioned patent to G. E. Duffy, Sr, Pat. No. 2,4l4,583,'dated January 21, 1947, to which reference is to be madefor a description more in detail as to the principles and theory of operation ofthe relay, thusthe description of the mode of operation herein included will be limited to that which is desirable for an understanding or" the improvements provided by the present invention, and it is to be understood that any theory of operation set forth herein is included to facilitate an understanding of reasons for the structure rather than to limit in any manner the scope of the present inventionor the application of other theories of operation.

' "A schematic wiring connection is illustrated in Fig. 2 for providing energization'of the relay Ri with one polarity or the other, or for the deenergization of the relay by the actuation of the switch SW, suitable connections being made to the contact tips 3'? and 33 to connect the windings 34' and E with proper polarity to act in series in the establishment of magnetic circuits in the U-shaped core structure.

With the switch SW in its normal center posi jtion'asshown, the windings 34 and 35 are deenergized, and'the permanent magnets PM i and PMZ; which are poled the same in their assembly in the relay provide a magnetcmctive force for three magnetic circuits' One of these magnetic circuits can be traced as extending from north pole or" the permanent magnets Phil and PM2 including the left-hand end of core armature 44, and the left-hand end of core to thesoutli pole of the permanent magnets Pivli and Plvii. A second magnetic circuit can be traced as extending from the north pole of the permanent magnets PMi and PM? through the right-hand portion of the core 24, yoke 43, and right-hand portion of core 25, to the south pole of the permanent magnets PMi and PMZ. A third circuit for the permanent magnets PMI and PME can be traced as extending from the north pole of such permanent magnets through the leakage strip L to the south pole of the permanent magnets PM! and PM2. The direction of the flux in the respective magnetic circuits which have been described can be assumed to be in correspondence with the sequence in which the respective elements of each magnetic circuit have been mentioned in the description of the magnetic circuits.

To consider the magnetic circuits of the electromagnet and the effect of such magnet on the attraction of the armature 44, it will be assumed that the switch SW is operated to a right-hand position to apply proper polarity of energization to the windings 34 and 35 for eiiecting the picking up of the armature 44. A circuit is closed under such conditions extending from the positive terminal of battery 55, including contact 5? of switch SW in its right-hand position, winding 34 of relay R5, winding 35 of relay RE, and contact 58 of the switch SW in its right-hand position, to the negative terminal or" battery 55. In response to such energization a magnetomotive force of the electromagnet establishes flux in a direction in the right-hand portions of the cores 24 and 25 in opposition to the permanent magnetic flux which has been established through these parts. The direction of magnetic flux of the electromagnet in the magnetic circuit estab lished through the armature 44, however, is the same as the direction of flux of the permanent magnets PMi and PM2, and therefore the density of flux in the armature 44 is increased to a point to cause such armature to be picked up against the action of the biasing spring 48, the flux through the armature having increased as a re-' sult of the shifting of permanent magnet flux from the magnetic circuit including the yoke 43 as well as because of the added flux of the electro* magnet.

The energization of the electromagnet with the polarity as described also establishes flux in the leakage strip L in a direction corresponding to the direction of the flux through such leakage strip as supplied by the permanent magnets PMI and PMZ. Inasmuch as the permanent magnets PMI and PMZ are magnetized sufficiently to normally substantially saturate the nonnotched portion of the leakage strip L, the leakage strip L offers a high reluctance to the flux of the electromagnet at normal operating values of magnetomotive force, and thus little of the I power of the electromagnet is lost by the shunt of the leakage strip L, in multiple with the armature 44. The magnetomotive force applied to the leakage strip L at normal operating values is insufficient to cause a substantial amount of flux to bridge the air gap of the slotted portion established in opposition to the flux of the permanent magnet in the right-hand portions of the cores 24 and 25, and thus allows the strengthening of the permanent magnet flux in those portions of the magnetic structure of the relay and the weakening of the flux in the magnetic circuit including the armature 44. The restoration of the armature 44 further decreases the flux density in the magnetic circuit including such armature because of the increased air gap in that circuit, and more flux is thus diverted to the magnetic circuit including the right-hand portions of the cores 24 and 25 and the yoke 43.

To consider the operation of the relay on reverse current, it will be assumed that the switch SW is actuated to its left-hand position to close the contacts 51 and 58 and pole change the circuit for the windings 34 and 35 of the relay RI as compared to the polarity of energization of such windings by the circuit which has been described. This polarity of energization of the electromagnet establishes electromagnetic flux in both the leakage strip L and the armature 44 in opposition to the permanent magnet flux in those magnetic circuits. For the armature to be picked up on reverse current it is necessary therefore that the flux in the armature be reversed in direction from that which is established by the permanent magnets PM I and PM2, and that it be of a sufiicient density, in the reverse direction, to attract the armature 44 against the action of the biasing spring 48.

It will be noted that the condition with respect to the leakage strip is somewhat different from that which has been described when considering the picking up of the relay by its normal polarity in that the flux must be neutralized in the leakage strip L and must be reverse in direction to an extent near saturation before sufficient mix-for picking up the armature 4,4 .wilLbe. di-

vertedto the magnetic circuit includingsuch armature andthesubstantial air-gap between that armature-and the pole faces 21 and 22. It is therefore establishedthat in order to operate the relay RI on-reversecurrent, the degree of energization of the relay must be manytimes its normal degree of :energization, -andvtherefiore the n value ofw 'agnetomotive forcetappliedtacross the leakage strip 1 L would necessarily ,be 1 many timesthat which isnormally applied across ,such

leakagestrip. I

Having thus described onespecifio embodiment .of; thepresent invention, it isdesired to :be understood that this. form is purelyillustrative-of the manner in which ,the ,present invention may wbe applied, .andflthat the :d-isclosureof this form should in-znoway limit the number of formswhich the invention. may assumes-and it-is tube further understood that-various adaptations, alterations zandamodifications-may be applied tothe specific formgshown to -meet the :reqtiirements of practice without inf-V any manner departing from the spirit or scope of the present invention Texcept aslimited bythe appended claims.

What we claim is:

51. {In-a relay having contacts operated by the ,energization. of ,an velectromagnet, the combina- ,tion withg two laterally spaced cores, of tim er- :manent, magnets: bridging saidcores on. opposite sides thereof, .said permanent ma-gnets i-havi-ng recesses; engaged-baa: U-shapedspring clamping said-magnets lto. thev sides of said cores,-said; spring limiting longitudinal v.movenrient :of said permaamazes nent magnets .by its .lwidth between said 3 coret being. substantially, comparable to the, space'between said cores.

, 2. In an electromagnet. having contacts operated by a-movablesarmature, the combination with twohlaterally spaced cores, oftwopermanent m nets bridging said ,cores on opposite -si des thereof, said permanent magnets havingfitnansverse slotsengaged by the respective. sides of a U-shaped spring; said spring clampingsaidmagnets.to the sides of ,said core,t.s,aidsprin g substantially bridging the. space between said cores to thereby limit longitudinal movement ofssaid magnets, and said springlmaintainingssaid magnets in laterally spaced axial alignment because of itsv engagement withsaid transverse slots.

JOSEPH E. WILLING. GEORGE a E. DUFFY, 1 SR.

REFERENCES CITED The iollowingirefferences are ofrecordinthe file of this patent:

UNITED STATES PATENTS FQREIGN l PATENTS Country .Date Great .IBritainv Mar.y9, 1932 Number 7 Number

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