Dec. 3, 1946. 2,412,123 R. E. H. CARPENTER 0 mmRd m ,GrNiE.l T 2 Sheets—$heet l 4M mm 520B H ma,2222 4E mmOO mg 4.y@ Q i'llllllllllllv J/m w m a/ o E@Fm Ebb/away OO/2. “2%1 9 D5, _n J.r.fm G W, x6 l7wl"W _087l./“IA_Q/ o Inventor Attorney Dec. 3, 1946. R. E. H. CARPENTER 2,412,123 ELECTROMAGNETIC- DEVICE Filed April 23, 1945 2 Sheets-Sheet 2 FIGS. Inventor magi VA3, ttorney 4W Patented Dec. 3, 1946 UNITED 2,412,123 STATES ' PATENT OFFICE 2,412,123 ELECTROMAGNETIC DEVICE Rupert Evan Howard Carpenter, South Croydon, England Application April 23, 1943, Serial No. 484,266 In Great Britain April 28, 1942 16 Claims. 1 <o1. 200-93) This invention relates to electric telegraph relays and other electromagnetic devices having vibratory armatures, and in particular is con cerned with such electromagnetic devices having 2 also the faces of members of the magnetic cir cuit which lead the variable flux into and out of the armature, it is possible to set the air gaps so that they all have the same lengths along the a magnetic structure which comprises a part pro- 5 magnetic circuit. Those lengths are adjustable viding a magnetic circuit of low reluctance to to the precise amount desired and the faces co carry the ?uctuating or reversing flux, and an operating with the armature can be made accu other part which provides two magnetic paths rately parallel with the armature faces whenthe in parallel for the steady polarising ?ux, and armature is in its mean position. Thus, thin which paths have a reluctance substantially 10 metal distance pieces may be inserted between greater than that of the low reluctance magnetic the armature faces and the co-operating faces circuit in which the armature oscillates and of the magnets and other members of the mag which includes the effective air gap. The inven netic structure. The parts may be set up against tion is applicable to devices to which varying these distance pieces, and then after clamping, currents or potentials are applied to produce a 15 the distance pieces, may be removed, leaving the corresponding vibratory motion of the armature, air gaps accurately adjusted as desired. including, for example, telegraph relays and driv It is convenient to employ two permanent mag ing units of sound reproducing instruments, and nets having like poles presented to the armature also to devices in which the vibratory armature and to provide the two members of the magnetic is driven to produce an electromotive force at 20 structure which serve as pole-pieces for the flue the output terminals of the device, as is the case tuating ?ux to face two other faces of the arma in electromagnetic pick-up devices for gramo ture. In a form of construction in which the phones. armature is a rectangular strip, the two perma nent magnets on the other two members are construction over that shown in my U. S. Patent 25 arranged transversely to the length of the arma The present invention involves an improved 1,826,990. ture and they form four magnetic limbs parallel The object of the present invention is to pro— to one another and at right-angles to the faces vide a form of magnetic device with a magnetic of the armature with which they co-operate. structure as set out above, which is relatively Such a construction is obviously convenient and efficient for a given amount of material in the easily assembled and set in the manner men magnetic structure and consequently lends itself tioned above, but it cannot always be adopted to being housed within a smallcompass. because in some cases where the conditions are According to the present invention, the mag such that the moment of inertia of the armature netic structure is arranged so that the excitation of necessity should be as low as possible, it is ?ux passes along separate paths in the structure 35 desirable to employ an armature which in end except where they pass through the armature. view has the shape of a lozenge, or of a rhombus Thus, the magnet or magnets which are provided of narrow width. In that case, the four magnetic to set up the excitation ?ux, may then be ar limbs referred to may be directed away substan ranged so that they present polar faces to one tially at right-angles from each of the four faces or more faces of the vibratory armature directly, 40 of such an armature from which, so to speak, that is to say, that the magnet or part of it, such they radiate, and are consequently inclined to as a pole tip, is only separated from the arma ture by the inevitable intervening air gap. As a result, the ?ux passes from the magnet to the armature, or on leaving the armature, to the 45 magnet directly or substantially directly, passing between those two members through the inter one another. In such a case, the armature can have a cross-section which at all points along the ?ux path in it is roughly proportional to the ?ux which it has to carry, thus permitting the reduction of its mass to the amount determined by the magnetic conductance needed. Moreover, vening air gap, and the magnet or magnets ex the inclined disposition of the magnetic limbs tend away from the corresponding face or faces co-operating with the armature presents the ad of the armature. 5O vantage of allowing them to be brought very close Apart from the relatively high e?iciency from to one another in the region of the armature the magnetic point of view, such an arrangement has de?nite mechanical advantages in that by mounting the magnets so that their settings rela tive to the armature can be varied, and indeed 55 without too much magnetic leakage between them occurring. Thus, the armature may be kept very short in the direction of the ?ux path, in. fact Of. a length little more than that deter ' 2,412,123 3 mined by the dimensions of the working or polar faces. In cases, however, in which it is desired to keep the magnetic limbs further apart, the armature may be of a section consisting of a ' 4 Figure 6 is a, diagrammatic illustration of a modi?cation of the construction in which an armature having the shape of a rhombus of nar row width is employed; while Figure '7 is a similar view showing a further modi?cation with a somewhat different form of short central portion with parallel sides and of tapering end portions. In these cases also the magnets and the pole members for, the variable armature. ‘ ?ux may be accurately set with respect to the The telegraph relay illustrated in ‘Figures 1 to armature by arranging them to slide along their 5 is mounted upon a base plate I made of non axes inclined to one another, or by forming them 10 magnetic material such as brass. On either side, with parts which are parallel and which can upstanding from the base plate, is a pile of lami slide in parallel grooves in a base plate to and nations 2, 3, made, for example, of the metal from the armature along parallel lines. known under the trade name “Radiometal” and Thus, any of the forms of device referred to forming side limbs of the magnetic circuits. The above may be built up on a non-magnetic base 15 bridge-piece or core 4 which carries the relay plate which is machined with shallow grooves winding 5 and which may be made, for example, in which the two permanent magnets and the of the metal known under the registered trade two pole-pieces or limbs which are common to mark “Mumetal,” extends between the side limbs the magnetic circuit which carries the ?uctuating 2, 3 which are cut away to receive the ends of the flux, and the circuit which carries the steady 20 core 4, as seen in Figures 1 and 4. The two polarising flux, ?t slidably for assembling pur_ cross-limbs 6, ‘I which form parts of the magnetic Then, when the parts are set truly in circuits which carries poiarising ?ux and ?uc DOSES. position by the use of shim strips or distance tuating ?ux, also made of the material known as ‘ pieces, as already mentioned, they may be “Radiometal,” consist of piles of laminations, the clamped in position on the base plate, for exam 25 individual laminations of which form a lap joint ple, by means of a suitably-shaped saddle or with those of the side limbs 2, 3. ,A strip of bridgepiece which can be pressed on to the parts Radiometal 8 is rivetted to the under surfaces of and held tightly in position. each of the cross-limbs 6, ‘I and ?ts in a corre spondingly shallow groove 9 in the base plate i. It is convenient to arrange the pivots for the armature near to the centre line of the permanent 30 This enables each cross-limb 6 or ‘i, together with magnets. The pivots may be arranged by pro the corresponding side limb 2 or 3, to slide in assembly to and from the corresponding surfaces viding the armature with lateral extensions to which a ?exible blade spring may be ?xed on of the armature Ill. The permanent magnets either side, the springs being anchored to a plat ii, l2 are preferably made of a modern magnet form on the non-magnetic base plate on the back 35 alloy having high retentivity and coercive force, and to the non-magnetic saddle or bridgepiece at such as the magnet alloy sold under the trade the front. If comparatively weak springs are em ployed, the armature can be made side-stable but name “Alnico.” The magnets are disposed with their like poles towards the armature EU, as in dicated by the letters NS in Figure 5, and may be by employing sufficiently sti? springs, it may be made centre-stable, that is to say, the springs 40 magnetised in manufacture through the faces are able to return the armature to the central through which the flux is required to pass. The position when, in the case of a telegraph relay or magnets butt against the upper surfaces of the the like, no signal or line currents are being re side limbs 2, 3, and the cross-limb stampings 6, ceived. The pivoting of the armature near to the 1, as seen in Figures 1 and 4, and they also make centre line of the permanent magnets increases a sliding fit in shallow grooves iii in the base the sensitiveness‘ of the instrument on the one plate I so that they too during assembly can hand, and on the other, the amount of movement slide towards or away from the armature III. In of the armature in the neighbourhood of the mag this way two parallel magnetic paths, shown by nets when moving over from one side to the other the dotted lines M in Figure 5 for the steady is comparatively small and does not cause much 50 polarising ?ux of relatively high reluctance, pass re-distribution of the ?eld between it and the from the magnets ll, I2 down into the cross magnets, and consequently reduces hysteresis limbs 6, ‘l, thence pass through the armature ill in parallel upwards, and back into the magnets helped by placing the magnets in direct relation H, I2. The magnetic circuit of low reluctance ship to the armature since, owing to the very 55 for the reversals ?ux is shown by the chain line high coercivity of the magnets themselves, very IS in Figure 5, and passes from the core 4 through little re-distribution of flux can take place in one of the side limbs 2, through one of the cross them which would not be the case were ?ux paths limbs 6, across the armature I0 into the other in iron to be provided as have been heretofore in cross-limb ‘I, and back through the side limb 3 such a type of magnetic structure. 60 into the core 4. In order that the invention may be clearly un The armature ill is generally of rectangular‘ derstood and readily carried into effect, an ex shape, its opposite faces being parallel to the ample of a fully worked-out telegraph relay in faces of the opposite cross-limbs 6, ‘I, and the permanent magnets H, l2. The armature is accordance therewith, and some modi?cations of the arrangement will now be more fully described pivoted in the region of the mid-line of the mag with reference to the accompanying drawings, nets li, i2, and is extended upwards and at the in which— upper and bears the moving contacts IS. The Figure 1 is a front elevation of the relay; side contacts or butts I‘! are adjustable and are effects to a minimum. Such reduction is also Figure 2 is a central vertical section on the line II-II of Figure 1; Figure 3 is a rear elevation of the relay; and Figure 4 is a side elevation seen from the left of Figure 3; Figure 5 is a diagram to show clearly the mag netic circuits employed in Figures 1 to 4; shown of the construction carried on damped compliant mountings, as set forth in patent speci?cation No. 2,219,222. A bridgepiece of brass I8 is provided for a double purpose, both for clamping the magnets H and I 2 and the cross-limbs 6 and ‘I, and also 75 to support the pivot at one end of the armature 9,419,193 10. The bridgeplece it engages over the upper surfaces of the magnets ll, i2 at the points fl, and also engages below the under surfaces of the lateral limbs 8, ‘i at the points 20, so that it acts as a saddlepiece for the magnets and the lateral limbs. The bridgepiece I8 is secured to the base plate I from the back by means of screws 2|. Also screws 22a and 22b are threaded in the bridgepiece i8 and their points respectively bear on the front faces of the permanent magnets ii. l2. and of the cross-limbs 8, 1. Hence, when these screws 22a, 22b are somewhat loosened, the mag nets ll, l2, and the cross-limbs 8 and ‘I can slide or be pushed within the shallow grooves l3, 8 to cause them to approach to or recede from the armature l 0 and can then be clamped by tighten ing up the screws. The pivot of the armature Iii consists of a square extension 23 towards the back and a 8 . With all'the parts thus finally tightened up, the shims can be withdrawn. ' In the form of construction shown diagram matically in Figure 6, the armature ll, instead of being rectangular, has now the shape of a narrow rhombus, as seen in end view. Its moment of inertia can, therefore, be made small relatively to its magnetic conductivity and it can be pivoted about the centre of gravity of the system comprising'the armature II and ‘the con tact tongue 33, for example, by means of a square spindle I4 furnished with suitable bearings or suspensions. The tongue 3| carrying the movable contacts I6 is also fixed to the spindle it. The magnetic circuit of the device is similar to that shown in Figures 1 to 5 except that the two permanent magnets II. I! are ‘not parallel to one another but are set substantially at right angles to theupper faces of the armature i0, similar extension 24 towardslthe front. At the 20 and the two cross-limbs 6, ‘I are similarly set with back, the extension 23 passes into a recess 25 their centre lines at right-angles to the two lower in ‘the base plate I, and a ?exible blade spring faces of the armature ll. For assembling pur 26 is ?xed to its upper surface by a- screw 21. poses, the magnets ll, l2 and the cross-limbs i, The blade spring 28, is anchored to a platform ‘I may be caused to fit in inclined'shallo'w grooves on the base plate I on either side of the recess 25 in a base plate similar to the'plate I in Figures 25 by screws 23. Similarly, at the front of the 1 to 4, but as illustrated diagrammatically, the bridgeptece i3 is recessed to receive thearma cross-limbs 6, ‘I are made in one with the side ture extension 24 which, as at the other end, is limbs 2, 3 and each of these composite units has secured by a screw 21a to a thin blade spring 28a a brass strip 38, 31 ?xed to its rear face and ar which is anchored on either side to the bridge 30 ranged to slide in shallow grooves in the base piece by screws 28a. Thus, when the armature plate, while in a similar way each of the is rocked, the two blade springs 28, 26a can yield permanent magnets II, II has secured to its sumclently to accommodate the relatively small rear face a brass strip 38, 39 so that both the movement necessary, and upon any movement cross-limbs 8, ‘I and the magnets ll, l2 can be of the armature sideways, both blade springs are caused to slide all in the same direction before‘ placed under tension. As already mentioned, the being ?nally secured in position in the manner springs 28, 26a may allow the contacts it to be already described with reference to Figures 1 to drawn over on either side, in which case the relay 5. In this case, however, for accurate setting up, is side-stable or may be stiff enough tomaintain it is desirable to provide either four separate the contacts in the central position when there 40 thin shims, or two shims each consisting of two is no current on the relay. parts inclined to one another. For biassing the relay, a bar magnet 29 is It is clear that a movement such as illustrated pivoted to the back of the base plate I at the in Figure 6 could be used for a high frequency point 30 and can be turned to one side or the relay or with a slight modification as the ener other in a recess 3| in the base plate i to set 4.-1 gising movement of a loud speaking telephone, in the bias of the relay to neutral. 1 which case the vibrating armature I. may be In assembling the relay, the side limbs 2, 3 connected to the telephone diaphragm by any with the cross-limbs O, ‘l are placed in position suitable connection between the square spindle. on the base plate i with the strips 8 in‘their 34 and the diaphragm. grooves 9 in the base plate, the two permanent In Figure '7, a form of construction is shown on magnets II and i2 are placed in their grooves l3, much the same lines as that shown-in Figure 6 and the bridgeplece i8 is ?xed in position by the except that in this case the armature J I, as seen screws 2| and with the screws 22a and 22b _in in side view, has the shape of ‘a thin wedge with serted but not screwed up tightly. The armature its base curved as an arc struck from the centre I0 is placed in position and a shim strip, say i of the spindle 34. The arrangement of the con 0.006 of an inch'in thickness, is inserted between tact tongue 35 and of the cross-limbs 3, ‘I and the the armature on one side and the face of the side limbs 2, 3 may be .the same as in Figure 8. magnet ii and of the limb I and on the other although the means for guiding them during side, between the armature and the magnet i2 assembly in grooves in a base plate are not shown. and the cross-limb ‘I. Then, before the screws (1i) The magnets il, i2, however, are in this case at 22a, 22b are tightened up, the magnets ll, i2 right-angles to the side plates 2, 3 and can there and cross-limbs 8, ‘I are pressed in against the fore slide directly in shallow grooves in a brass shims which ensures ?rst of all that the arma base plate. Their inner like poles are shown ture Ill is set square to the magnets and lateral abutting and are machined to the shape of the limbs, and also that the two magnets and the curved surface of the armature I‘, but clearly two pole-pieces are equally distantly spaced from in order to allow latitude in .the width of the air the opposite faces of the armature l0. At that gap between them and the armature, as deter stage, the two screws 22a, 22b can be tightened mined by the insertion of an arc-shaped shim, to clamp the magnets i I, I2 and the limbs 8, ‘I the magnets ll, l2 would barely come into con in position, and also two screws 32 threaded in tact when ?nally set up. Generally speaking, right-angle brackets 33 rivetted to the base plate the form shown in Figure 7 operates in the same i are screwed in so as to bear against the core way as that shown in Figure 6, and the magnetic 4 and hold it in position. Finally, the screws 21 circuits of both of. them are similar to those and 210 which had been loosened to prevent shown in Figure 5. ‘ distortion during the assembly, are tightened up. If a strictly triangular armature is employed, 2,419,128 . > ' ' 8 7 there must be su?lcient clearance between the permanent magnets H, I! andthe base of the _ ing a portion thereof positioned in said air-gap, armature to allow the latter to vibrate to the luctance bridging said air-gap and ‘also having required extent. In any of the forms of construction described, an air-gap in which another portion or said vi the reluctance of the magnetic circuits, including the ?eld magnets ll, l2, may be increased by leaving gaps between the side limbs 2, 3 and the magnets II, I! orotherwise in order to reduce magnetic shunting of the lateral limbs 6, 1 with 10 path embodying means for establishing a polariz ing ?ux in the portion of said armature lying be respect to the ?uctuating ?ux. magnetic structure forming a path of high, re bratory armature is positioned, said bridging tween said air-gaps, said polarizing ?ux having one polarity in one air-gap and_the opposite polarity in the other air-gap, and an actuating coil for establishing a ?ux in said magnetic cir " In all three arrangements illustrated in Figures cuit oi’ low reluctance. 5 to ‘7 inclusive the pivotal axis of the armature 5. An electromagnetic device according to claim is located substantially at the point of juncture of 4 wherein the air-gap of said bridging path ‘is ' the two polarizing ?ux paths from magnets I I 15 formed between like poles of a pair of permanent and I2. Due to the location 01' the pivotal axis magnets included in said path on opposite sides and to the shape of the armature, vibration of of said armature. the armature in all three arrangements does not 6. An electromagnetic device according to materially change the reluctance of the two gaps claim 4 wherein said vibratory armature is piv between the armature and magnets I I and l 2. 20 oted for oscillation about an axis positioned with- . in the air-gap of said bridging path. -l. An electromagnetic device of the class set 7. An electromagnetic device according to forth, comprising a magnetic structure including claim 4 wherein said armature is pivotally mount a magnetic circuit 01 low reluctance, a pair or ed for oscillation about an axis located substan ‘pole-pieces in said magnetic circuit abutting on 25 tially at the point of juncture of the two polariz the effective air-gaps oi’ the device, polarizing ing ?ux paths from opposite poles of the air-gap means for establishing the polarizing ?ux for the in said bridging path. device, a coil linked with said magnetic circuit 8. An electromagnetic device according to of low reluctance, and a vibratory armature piv claim 4 wherein said armature is provided with Iclaim: - > oted at or near its centre of gravity to move to 30 an arm extending beyond said bridging path, and “ and from each of said pole-pieces and shaped includingmeans pivotally mounting said arma with a varying section perpendicular to its neu ture substantially at the center of gravity oi.’ the tral axis, said section being greater where the vibratory mass. , ?ux in said armature is greater. 9. An electromagnetic device according to 2. An electromagnetic device of_ the class set 35 claim 4 wherein said armature comprises a mag iorth, comprising a non-magnetic supporting netic piece of rhombic shape and the pole faces plate, a magnetic structure mounted‘on one side of said air-gaps are arranged at angles to each other and parallel with the adjacent faces of said thereof and including a pair of pole-pieces each with a race adjacent one of the effective air-gaps‘ rhombic piece. ' of the device,.a magnetic bridge piece connecting 40 10. An electromagnetic device comprising,' said pole-pieces to form a magnetic circuit of low in combination, a non-magnetic supporting plate, reluctance, a pair of magnet members co-operat a pair of magnetic pole pieces, means for locating ing with said pair of pole-pieces to form two mag and guiding said pole pieces on said supporting netic circuits for a polarizing ?ux with two paths plate for adjustment towards and from each other in parallel, the elements of said magnetic circuits 45 to form an air-gap of variable width between said being mounted so that the planes of all three pieces, means for clamping said pole pieces to said magnetic circuits are arranged substantially par plate in adjusted position, a magnetic bridge allel with the face of ‘said supporting plate, a V1 piece connecting said pole pieces to term a mag bratory armaturepresenting faces each adjacent netic circuit of low reluctance, and an actuating one of said effective air-gaps and mounted on 50 coil linked with said bridge piece. ' the same side of said plate to co-operate with 11. An electromagnetic device comprising, in said magnet members, said two magnetic circuits combination, a non-magnetic supporting plate, a presenting a path in parallel with said eii'ective magnetic structure mounted on one side of said air-gaps having a reluctance large compared with plate and forming a magnetic circuit including that of said air-gaps, and one or more of the ele ments comprising said pole-pieces, said magnet members and said armature being mounted on said plate so as to be slidable for adjustment dur ing assembly. an air gap formed between a pair of pole pieces in said circuit, a magnetic vibratory armature mounted on said plate and having a portion there - of positioned in said air-gap, means for mounting at least one of said pole pieces for adjustment to 3. An electromagnetic device of the class set 60 and from said armature to vary the air-gap be forth, comprising a vibratory armature and a tween said armature and said pole piece, and magnetic‘ struct e including a pair of ' pole ‘means for clamping said adjustable pole piece to pieces each pres ing a face to said armature, said plate in adjusted position. a pair of magnet ' embers co-operating with said - 12. An electromagnetic device according to pair of pole-pieces to form two magnetic circuits 65 claim 4 and including a non-magnetic plate sup for a polarizing ?ux with twobpaths in parallel, porting said magnetic structure, and wherein the and each magnet presenting a pole face directly air-gaps in the low reluctance magnetic circuit to said armature, said armature being mounted and in the bridging path are both formed between so as to be slidable and rotatable relatively to pole pieces movable towards and away from said said pole-pieces and said magnet members for 70 magnetic armature during assembly, and means adjustment dm'ing assembly. for securing said pole pieces .to said plate in ad - 4. An electromagnetic device comprising, in 7 ‘ iusted position. combination, a magnetic structure forming a 13. An electromagnetic device comprising, in magnetic circuit of low reluctance and having combination, a non-magnetic supporting plate, a an air gap, a vibratory magnetic armature hav 75 magnetic armature having a rhombicshape piv 2,412,123 10 , otally supported on said plate, a pair of perma nent magnets supported on said plate so that one end face of each magnet is presented to one face of said rhombic shaped armature, a pair of mag netic pole pieces supported on said plate so that one end face of each pole piece is presented to one of the remaining faces of said armature, means including shallow grooves formed in the surface of said plate for mounting said magnets and said pole pieces for adjustment to and from 10 located within said gap, 9. pair of blade springs supported on said base, and means for clamping said arms to said springs whereby said springs serve to position said armature centrally of said 88D. , 16. A polarized electro-magnetic relay com prising an energizing coil having a magnetic core, an elongated vibratory magnetic armature mounted adjacent said coil and having its longi tudinal axis directed substantially through the axis of said‘core, a magnetic circuit of low re luctance Iormed between the ends of said core and including a pair of spaced pole pieces mount ed on opposite sides of theend of the armature eluding integral arms extending on either side of 15 nearest said coil, a magnetic path of relatively said armature. , 1 >14. An electromagnetic device according to claim 3 wherein said vibratoryarmature is piv-\ otally supported upon’ a base by a structure inf said armature in the direction of its pivotal axis, a pair of blade springs supported on said base and extending into engagement with said arms, and means for adjustably securing said arms-to said springs. " - 15. An electromagnetic device comprising, in combination, a supporting base, a magnetic struc ture mounted on said base and comprising a, mag netic circuit having an air-gap therein, a mag high reluctance completed between the ends of said core and including a‘pair of magnets having like poles thereof arranged on opposite sides of I said armature adjacent the pivotal axis thereof, 20 a contact arm carried by said armature and ex tending to the opposite side of its pivotal axis from said coil, and stationary contacts cooperat ing with said contact arm, said elements being arranged so that the centers of said contacts, the netic armature positioned in said air-gap, and 25 center lines of said pole pieces, the center lines means for pivotally supporting said armature of said magnets, and the axis of said core are all upon said base on an axis passing "through said positioned substantially in the same plane. gap comprising integral arms extending inoppo site directions from a portion of said armature JRUPERT EVAN HOWARD CARPENTER.