US2505904A - Holding relay with permanent magnet - Google Patents

Description

May 2, 1950 L. H. MATTHIAS ETAL HOLDING RELAY WITH PERMANENT MAGNET 3 Sheets-Sheet 1 Filed May 28, 1945 INVENTOR-S IUTOP/Vf).

y 2, 1950 L. H. MATTHIAS ETAL 2,505,904

HOLDING RELAY WITH PERMANENT MAGNET Filed May 28, 1945 3 Sheets-$heet 2 ATTOR/VE X y 1950 L. H. MATTHIAS ET AL HOLDING RELAY wrm PERMANENT MAGNET 3 Sheets-Sheet 3 Filed May 28, 1945 Q FUN llll HH Q g 4 F m I l M m KQYR IN V EN TORS /mm BY ATTOPl/[X I Patented May 1950 I UNITED 'S TA-T Es, jPATiEIN T o1=1= cE-} HOLDING RELAY wrrn PERMANENT MAGNET Lynn H. Matthias, Fox Point, and Karl K. Stong, Whitefish Bay, Win, assignors to Allen-Bradley Company, Milwaukee, Wis., a corporation of.

/ Wisconsin 1 Application May 28, 1945, Serial No. 596,360

This invention relates to electromagnetic attracting and holding apparatus dependent upon permanent magnetism for the holding action thereof; The invention resides more specifically in an improved form ofapparatuses of this type in which a permanently magnetizable core'portion is so disposed, intermediate the ends of a magnetizing coil, as to be subjectedv as nearly as possible to the full magnetizing force of which 7 result, excessive pounding and wear of mechanical as well as electrical parts has been encountered. I

A furtherdisadvantage of magnets heretofore planet-5 there indicated;- and Fig." 6 is a diagram of one form of circuit which -a Claims. (01. 1 -341) of the relay shown in Fig. I viewed through the maybe employed with the apparatus shown in the preceding figures.

.Referring now to the drawings the magnet of this invention is there shown associated with parts adapted to form an electric relay, for which use the magnet is particularly well adapted. As appears more clearly in Figs. 4 and 5 a magnet frame I of rectangular "U-shaped iorm is secured by rivets to a mounting bracket 2, thus forming not only a magnet frame but also a supporting framework for the entire rclay The upp r ends of the upwardly facing prongs of the U-shaped frame I are provided with bent back ears 3 to provide means for firmattachment through screws 4 with a top frame plateii. In this way a recavailable has been 'the tendency thereof to close i when unduly low'voltage is applied and then on termination of such deficient voltage to drop open again instead of remaining latched. Through the use of the apparatus of this invention the shortcomings of magnets of thistype previously tangular, open sldedmagnet frame is formed composed of magnetic material of comparatively high magnetic permeability and low retentivity.

Permanently secured in a centrally disposed hole in the upper plate 5 is a downwardly ex-* tending upper core member 6 held in place by a peened rim l. The upper core member 5 is composed of magnetic material of high permeability andlow retentivity and is provided with an accurately machined lower face 8. Disposed beneath and spaced from the upper core member '6 is a lower core members formed oi! similar material; the upper face ill of which is also acknown is overcome. The magnet of this invention iseasily permanently magnetized by a magnetizing force not materially greater than that appropriate for pick up and closing. In this way v undue pounding and wear may be avoided. Furthermore, any applied voltage sufficient to cause pick up and closing also is adequate to establish sufilcient permanent magnetism to insure the retaining of the magnet in closed position. y This invention is herein described by reference I to the accompanying drawings forming a part hereof and in whichthere is set forth by way of illustration and not of] limitation oneform in which the apparatu of th s invention may be embodied. Inthedrawings:

Fig. 1 is a side view in elevationof' a relay embodying amagnet constructed inaccordance with thisinvention;

Fig. 2 is a-top planivlew or the relay shown in' Fig. "1 with the upper contact cover removed to expose the contacts; r

Fig. 3 is a bottom plan view of the relay shown in Fig. 1 with the bottom contact cover removed; Fig. 4 is a side elevation in section of the relay shown in Fig. 1' viewed through the plane 4-4 indicated in Fig 2; v 1'18. 5 is a Iront view in elevation and in section tentivity and coercive force.

curately machined. Disposed between and'in intimate engagement wlththe faces 8 and i0 and there rigidly held bythe tubular rivet i I lean intermediate core member 12.

The intermediate core member i2 is composed of a magnetic material of exceptionally high readapted for the construction of the intermediate core member l2 are the alloys of iron, aluminum and nickel orcobalt of the general class commonly called Alnicof However, any material exhibiting the property of retaining permanent I magnetism to a high degree may be employed and for this reason a successful practicing of this invention is not dependent upon the selection of the particular alloy or alloys above mentioned for the intermediate core member I2.

The parts above described constitute the entire stationary frame of the magnet and with these parts a coil i3 is associated in a particular manner so as to produce the specific magnetizing action required. As may be observed in Figs. 4 and 5 the coil "surrounds the upper and lower coremembers 6' and 9 and notionly surrounds the intermediate core member l2 but extends a very substantial distance beyond the same both above and below it. By reason of this construction the flux created upon the energization of coil i3 is.

Particularly well g r at or in the nearvlcinity ofthe eye of the coil I3. Coil I3 may comprise if desired two separate windings as is set forth in Fig. 6, in which winding I3ais a closing or magnetizing winding and lib is an opening or demagnetization winding which creates a flux or opposite polarity to that of winding I3a.

- Immediately below the core member 9 a large I circular opening it is formed in the lower hori- Disposed zontal part of the frame member I. to move to and from the positions shown in Figs. 4 and 5, within the opening I, is a collar shaped armature I5 having a vertical sleeve portion l6 and a seating rim I7. As appears in Fig. 4 the seating rim I1 is arranged to come into sealing engagement with the bottom face of frame memher I while a small air gap is retained between the upper end of the sleeve l6 and the lower face of the lower core member 9. l

Armature I5 is mounted upon and guided in its movement by a non-magnetic guide rod I8, received with a close but nevertheless freely sliding fit within the bore of tubular rivet I i. To

form an engaging seat between the armature l5 and the rod l8 a boss I9, riveted in place within the armature I5 as shown, is bored to be closely received upon the reduced diameter portion 20 of the rod I8. The armature I5 isheld in place against. a shoulder on rod it formed by a reduced diameter portion 20 by means of a preloaded spring. ZI interposed between the armature I5 and a lower insulating'movable contactcarrier 22 held in place by a C washer 23 which engages a groove in theend of rod I8. To aug v ment the opening force due to gravity and to render the magnet operative in inverted position an opening compression spring 25 received within the recesses in lower core member 9 and armature l5 and interposed between these two place by screws 71. Mounted upon contact support 27 is a pair of closed-position stationary load contacts and terminals 28 and an oppositely disposed pair of open-position stationary load contacts and terminals 29. Also mounted upon the contact support 2] is a pair of stationary closedposition pilot contacts and terminals 3@ as well as a pair of open-position pilot contacts and terminals 3 i Mounted upon the upper end of the actuating rod l8 and there held between a c washer 32.

en ing a groove in the upper end of rod it, and a spring 33 engaging a shoulder 38, is an insulating movable contact carrier 35. The movable contact carrier 35 is so disposed as to carry movable bridging contacts 35 and 8? between load contacts 28 and 29 and to carry bridging contacts l8 and 39 to and from pilot contacts 30 and II. Secured to posts 40 and M by means of sleeve .nuts 42 and 43 is an upper contact cover 4 3.

Mounted on the lower face of frame member I by means of brackets 45 and screws 46 is a lower stationary contact support 4'! composed of insulating material. Carried by the support 47! are stationary load contacts and terminals 48 and 49 in position to be engaged by movable bridging contacts 50 and II carried upon movable insulating contact carrier 22. Stationary cross connecting contacts 52 serve to complete a load circuit from tel 48 to terminal when the switch is in closed position. A lower contact cover 53 positioned as shown is held in place by sleeve nuts 54 and 55 which engage threaded supporting posts it and 51! which in turn are secured to the contact support il by riveting.

Binding posts 58, 59, 50, Si, 52 and 63 serve to provide connection with the windings 13a and I327 of coil l3 and the pilot contacts 86 and 3! and with a control circuit as shown in Fig. 6 for energization of the magnet to cause the same to close and open.

As shown in Fig. 6 direct current supply main 6% of positive polarity is connected by lead 88 with a normally open start push button bl which is joined by a lead B8 with terminal 59 and one of the two stationary pilot contacts 33. Movable pilot contact 38 which is normally closed engages the other stationary pilot contact at which is joined through lead 69 and terminal 58 with closing winding Mia. The opposite end of closing winding Isa isjoined through terminal til and lead it with the negative power main 55. Winding I3a is of appropriate resistance and number of turns to cause closing of the magnet and permanent magnetization thereof;

For opening main is joined by lead ll normally open stop push button 12, lead 73, terminal 62, contacts 3i and wand lead it with terminal Bl at one end of winding 63b. The opposite end of winding 83b is joined through terminal 53 andlead i5 with positive power main 66. With the magnet in closed position, closure of stop button 12 completes a circuit for the creation of reverse flux in winding l3!) of a reduced magnitude limited by resistance it which may be either a distributed internal resistance in the winding I3b or an external resistance as shown. Such limited reverse flux serves to demagnetize the hard core portion 62 to cause the magnet to open. Numerous forms of such circuits ma be employed to accomplish the result desiredv including circuits which have but a single winding in coil I3 with external resistance arranged to be introduced when reverse polarity opening current is applied.

Upon excitation of coil ii for closing, the flux prevailing the magnetic circuit begins to build up but movement of ature is does not take place initially because of substantial leakage of flux from the lower face of core member 9 to the lower horizontal portion of frame I without pass; ing through the armature it. As flux further increases, a substantially larger portion thereof begins to pass from the lower face of core menn ber t to the armature l5 and thence to the frame 9. When the flux paming through the armature 55 reaches a value suficient to create an attractive force capable of overcoming the action of spring 26 and other resistingjorces, the armature i5 starts to move. By the time such movement starts to take place flux has been built up to a very substantial value, sumcient to establish considerable permanent magnetism in the intermediate core member 82. As movement of armature l5 progresses, the leakage of fiui: directly from thelower face of core member 9' to frame 9, is very rapidly diminished, until substantially all of the flux passes through the a raeoam During the closing action theflux in the mag could pass from the core member to the frame member I or to the upper plate without passing through the part to be permanently magneticed. This action would be further encouraged by the fact'that alloys suitable for permanent magnet use do not have thehighest possible permeability. By reason of the relationship of the parts ,of the apparatus of this invention a certain definite minimum excitation of coil 13 is necessary to cause pick up of thearmature. Any excitation exceeding such minimum will cause the armature ii to close and close positively and at the same time will insure the magnetization of intermediate core member I2, sufflciently to insure the retention of the magnet in closed position.

' It is not necessary to excite the coil I 3 to any degree in excess of that necessary to cause the picking up of armature IS in order to create the necessary permanent magnetism to retain the magnet in closed position and therefore the magnet ofthis invention may be operated without unnecessary mechanical wear and tearand with the full assurance that closing will be positive and reliable.

We claim as'our invention:

1. In an electrically controlled permanent magnet the combination comprising a central magnetic 'core having a relatively short medial portion composed of permanently magnetizable material exhibiting high coercive force and high retentivity and relatively longer end portions of magnetic material of high permeability disposed on opposite sides of said medial portion and in contact therewith, said short medial portion extending entirely across and completely separating said end portions; windings surrounding said core and extending lengthwise thereof beyond said medial portion on both sides thereof; a magnetic frame member surrounding said core and said windings having a magnetic top end plate secured to the top end of said core, apair of magnetic side legs secured to said top end plate extending downwardly outside of said windings,

' magnet the combination comprising a central magnetic core havingia relatively short medial portion composed of permanently magnetizable material exhibiting high coercive force and high retentivity and relatively longer end portions of magnetic material of high permeability disposed on opposite sides of said media1 portion and in contact therewith, said short medial portion extending entirely across and completely separating said end portions; windings surrounding said core and extending lengthwise thereof beyond said medial portion on both sides thereof; a mag- .netic frame member secured to and extending laterally from the top end of said core 'and downwardly outside of said windings terminating in' a lower end plate transversely positioned with respect to said core andextending across the free end of said core a predetermined distance beneath the free end of said core; said lower end plate being provided with an aperture disposed opposite the free end of said core; a movable armature having a shank portion freely movable within said aperture having a length approximating the spacing between the free end of said core and said lower end plate, the lower end of said armature being provided with a flangeadapted to abut the lower margins'of the aperture in said lower end plate when said armature is in closed position with the upper end of the shank portion of said armature in close proximity to the free end of said core; guiding means for said armature adapted to guide the same for free movement withinthe aperture in said lower end plate; stop, means positioned to maintain said armature when in open position at a level such that the upper end of the shank portion of I said armature is approximately flush with said lower end plate to provide a leakage path for a substantial proportion of the flux which threads said core directly between the lower end of said .0016 and said lower end plate without passage through said armature when said armature is in open position, and opening means adapted to urge said armature to open position.

3.111 an electrically controlled permanent magnet the combination comprising "a central magnetic core having a relatively short medial portion composed of permanently magnetizable and a magnetic lower end plate secured to said t core, spaced from and extending across the free I end of said core; said lower end plate being procontact the lower surface of said endplate ad-.-

iacent to said aperture when said armature is in closed position; and an opening spring disposed side legs in perpendicular relationship to'saidl material exhibitinghigh coercive force and high retentivity and relatively longer end portions of magnetic material of high permeability'disposed on opposite sides'of said medial portion and in contact-therewith, said short medial portion extending entirely across and completely separating said end portions; windings surrounding said core and extending lengthwise thereof beyond said medial portion on both sides thereof; a

magnetic frame member secured to andextending laterally from the top end of said'core and downwardly outside of said windings terminating-in a lower endv plate transversely positioned with respectto said core and extending across the free end of said core a predetermined distance beneath the'free end of said coreysaid lower end plate being provided with an aperture disposed opposite the free end of said core;

- a movable armature having a shank portion free- 1 1y movable within said aperture having a length v approximating the spacing between the free end between said armature and core adapted'to urge said armature to open position, 2. In an electrically controlled permanent of said core and said lower end plate, the lower end of said armature being provided with a flange adapted to abut the lower margins of .the aperture in said lower end plate when'said armature is in closed position with the upper end of the shank portion of said armature in -close proximity to the free end of said core;" av guidin: rod

tor-said armature extending axially through said core adapted to guide said armature for tree plate; stop means positioned to maintain said movement within the aperture in said lower end 4 and-said-iower end plate without passage through said armature when said armature is an open sition; an opening means adapted to urge said armature to open position.

aooam The 'foli owinkfreifrences are of record in the Number mamas #:w sums PA Date Name Gheney -Z. July 14, 3968' Warren Jami. 1918 Lane Aug. 39,1921

' Brown Apr. 12, 1

Ray Nov. 2, 193'? Stahel Dec. 21, 1937 Kelley Mar. 21, 1939 Perry Aug. 22, 1939 Van i lamenburg et a1. a. Oct. 1?, was

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