US2172460A - Electromagnetic device - Google Patents

Description

Sept. 12, 1939. c. F. wARRlcK ELECTROMAGNETIC DEVICE Filed Sept. 2l, 1936 y Patented sept. 12, 1939 i 2,172,460

UNITEDy sTArEs-"PA TENT OFFICE ELECTROMAGNETIC DEVICE charles F. Warrick, Detroit, Mich., assignorito Bender-Warrick Corporation, Birmingham Mich., a corporation of Michigan Application September 21, 1936, Serial No. 101,710 s claims. (ci. 'm5-sas) This invention relates to electromagnetic de- Then, too, a piece of dirt or other extraneous matvices, and has to do especially with devices of ter may get in between the surfaces and a noise the type where an amature or the like is to be condition created which gets greater in use. attracted into abutting relationship with another Moreover, the' battering of the surfaces may soon li element which serves as a stop, and which may destroy the accuracy of the machining so that a I 170. and may be useful where the direct current is where alternating current is used.

be the core piece of the electromagnet. 'Ihe innoise' condition results. Sometimes the device vention is particularly applicable to devices of has-'been mounted in rubbery to minimizethe thistype utilizing alternating current, although transmission. of noise through metallic` parts, theI invention may be used with direct current and to cut 'down the hum which may be present lo pulsating. In this class of devices are such items Devices of this type for use with alternating as relays, motor starters, vibration devices, eieccurrent are usually constructed of laminations trical controlling devices, etc. so as to reduce as much as possible the sofcalled The, principal object of the invention is to eddy currentsy which may be-induced inthe iron 15,'provideadevice ofthe character mentioned which cores by the alternating magnetic flux. This u will give a quietness of operation, and which will form of construction, namely, the laminated coneliminate many of the troubles and diillculties struction, may be advantageously employed in and .problems heretofore encountered in an eii'ort carrying out the present invention. However, in to construct such devices so that their operation the prior laminated Structures the lminatlons 27.0 is quiet or noiseless. were tightly bolted or riveted together so that in M Heretofore in electromagnetic devices arranged effect the core and armature constituted one solid to be used with alternating current the so-called metal mass, so far as the function in contacting shading coils have been employed .with the view each other is concerned. The laminations perof minimizing the vibration or hum due to the formed no function from a noise-minimizing 25 alternate setting up and breaking down of the standpoint, but were merely to minimize the eddy si flux. Briefly, these shading coils delay some of currents.

the iiux sothat when the ilux through the un- In carrying out the invention the armature shaded portion is at zero, the delayed ux serves or stop element against which the armature is to lreepv the amature attracted. These devices attracted, which may be the D018 pieces 0f a m38- 30 are only a partial remedy from the standpoint netic core, or both. aremade up 0f a plurality 30 of the objects to be attained by the present inmore or less looselyassociatedor relativg'elymovivention. 'I'he present invention maybe usedwith able pieces. 'I'he armature, for exampleymey shading coils, with the view of more or less evenbe made of a plurality or a multiplicity of seping out the iux curve. arate` pieces, capable of movement relative to 35 Where a solid armature strikes a solid stop or each other so vthat when the armature strikes core piece,thereis a resultant blow which creates a stop Aor pole the several pieces may adjust noise. This is particularly true where'the abutthemselves or seek their own seat 888111812 the ting surfaces do` not come together evenly, or in surface of the stop. Th if there iS a high other words where there are one or more high point in the contact this point may ail'ect only o spots whichtake the initial blow. Much work one piece of the amature and doesnot take the 40 has heretofore been done onfthese devices in mablow of the entire armature, land in this action chining and grinding the surfaces but this leads the other pieces seek their Own individual Seats, to dimculty in that, if the surfaces are. very whether on'a high spot ora low spot.

accurately ground for surface to surface contact In carrying out the invention a laminated L5 to eliminate noise. then the two pieces, namely, l structure maybe employed but the laminations 45 the armature and the stop. tend to stick together are so associated with each other that they 'are when the magnet no longer attracts the armature. relatively movable so that each lamination acts This action may be likened to a suction cup, as as a separate piece and can ilnd its own seat or the surfaces meet so perfectly that practically adjust itself tothe particularportion of thestop 0 an air tight contact is obtained and the vacuum or member against which it is to abut. .This 50 condition created prevents the armature from structure may be incorporated inthe armat being released. 'I'his is a bad condition because or a stop such as the core ofthe electromagnet. the force required to vrelease the amature is too or both. 1 great as the force has to be overcome the next In the accompanying drawing;

5 time the magnet is to attract the armature. Fig. 1 is a general view illustrating an electi'o-v 55 magnetic device comprising a core and an armature and constructed in accordance with the inventi'on.

Fig. 2 is a side elevational view looking substantially on line 2-2 of Fig. 1.

Fig. 3 is a cross-sectional view of the armature looking substantially on line l-I of Pig'. 1.

Fig. 4,4 isa detail of one form of spring which 4constantly connected to an alternating current line and the cross bar 4 constitutes a magnetic shunt. Around the shunt is a coil l connected to leads l. The le pieces of the core are illustrated at 1. ow this is merely exemplary of kone kind of core which may be used and is of the type shown in my Patent No. 1,979,127 of October 30, 1934. 'I'he function is briefly as follows: The alternating current in the coil 3 oontinuously sets up alternating flux which is shunted through the shunt l so that the same is ineffective to attract the armature. The leads 8 may extend, for example, to a controlling device such as electrodes or a thermostat, or the like (not shown) which upon certain conditions closes the circuit through the coil 5. Coil 5 then serves as a choke for the shunt i and the flux set up by the coil 3 seeks a path across the poles and attracts the armature. This brief description is merely given to indicate how the armature, soon to be described, is attracted, although it is to be emphasized again that the invention is not limited to an electrical hook-up which operates in this manner, as any type of electromagnetic device may be used with the invention.

The armature is generally illustrated at I and it may be pivotally mounted so that it is substantially balanced on an arm II in turn pivoted as at I2, and the armature may be normally held away from the poles by a spring I3, or for that matter the armature may merely gravitate away from the poles.

As shown in Fig. 3, the armature has a laminatedbody composed of laminations I such as a series of iron or steel plates or strips lying inv superpOSed condition.

Now these laminations are arranged so that 'they are shii'table relative to each other and are not bolted down tight. One way of constructing the armature to this end is illustrated in Fig. 3,

"th-ls being merely exemplary of one form of structure for carrying out the invention. This structure includes side supporting plates I6 withpins I1 passing through apertures therein. The laminated plates may be mounted on relatively soft rubber sleeves I8 which extend through the laminations as shown, and the pins I1 may extend through the sleeves. curved form may be placed between each supporting plate I6 and the laminated body, the springs acting to press the laminations together -with spring pressure and reacting against the side plates. These springs may have notched ends as shown at 20 for fitting over the end pins A leaf spring I9 oi!A and rubber bushings while the central lportion may be apertured as at 2I for the reception of the center pin. The assembly may be completed by the use of spring clips of suitable-structure as shown'at 22A clipping over the ends of the pins opposite their headed ends, and a washer 2l may be placed between some of the clips and a side plate. In the form shown the arm II in reality is constituted by two spaced arms fulcrumed on the center pin I1.

Now this structure may be incorporated in the core, as illustrated in Fig. 5 where it will be seen that the core is made up of a body ot laminations 2B, side plates 26, pins 21 with rubber bushings 28 and springs 29, the assembly being completed by the clips III.

When the armature is attracted and strikes thel poles 1 the body of the armature composed of the loose laminations is flexible, the several laminations adjusting themselves so as to seat upon the surfaces of the poles, regardless of Whether or not th seating surface is regular or irregular. As the laminations adjust themselves the rubber of the sleeves I8 is distorted and flows to permit such action. The function may be likened to la single lamination striking the poles and it will readily be appreciated that there is no particular noise or pounding action because f of the light weight of the single lamination. The

several laminations act individually in this respect. If one lamination strikes the poles first it does not take the impact caused by the movement and inertia of the entire armature. It merely comes to itsvown lseat and then the other laminations come to their seats. The same action is obtained if the structure is incorporated in both the armature and core, or only in the core. 'Ihus if the contacting surfaces are not accurately machined the armature, being selfaligning so to speak, seats properly thereon. If any extraneous matter or a piece of dirt gets in between the abutting surfaces the parts merely adjust themselves to meet this situation. The structure also meets a situation where there is warpage in the parts which may destroy the initial proper alignment. The armature and pole pieces will not stick together even if they are very accurately machined and finished for a perfect seat, because air can get in between the laminations so as to break any vacuum tendency. In fact it has been found that the contacting edges of the laminations need not be flat, but may be rounded. This is illustrated in Fig. 6 where the rounded contacting edges of the laminations are shown at 3|.

The above description clearly sets forth how the quiet operation is obtained, and it will be appreciated that the particular structure shown is exemplary of the principle involved in this invention. It will likewise be understood that the invention may be used together with shading coils Where it is desirable to even out the flux curve where alternating current is used.

I claim:

1. An armature for an electromagnetic device comprising, a plurality of facing laminations, spring means packing the laminations together, and rubber elements passing through the laminations and which are flexible, whereby. the laminations may shift individually and adjust themselves to a surface against which the armature is attracted.

2. An armature for an electromagnetic device comprising, an armature body made up of a plurality oilaminations, supporting side plates,

vil

againstasuifaceofthecoreorotherstop.said.

pins carried by the supporting side plates and extending through the laminatlons. rubber sleeves over the pins Supporting the laminations so that they are shiftabie edgewise relative to each other by the ilexible action of the rubber, and spring means between the supporting plates and laminated body for packing the laminations 3. An electromagnetic device comprising in combination a core. a freely movable arm'a'tui"e positioned away fran the core' and mounted to be attracted bodily thereby and to move bodily away therefrom upon magnetic iluxv variation in which action the' armature strikes and -abuts against a surface of the coreor other stop. said amature comprising a plurality of laminations lying in planes substantially at right angles to said surface or stop and substantially parallel to said movement for direct contactI with the surface or stop with their' edge portions, flexible means for holding said iaminatlons together' so that they normally move as a body, said means arranged to ilex so that individual may adjust themselves individually to the said surface or stop when attracted thereagainst mag netically. l

' 4. An electromagnetic device comprising in combination a core. a freely movable armature positioned away from the core and arranged to be bodily attracted thereby and to move bodily away therefrom upon magnetic tlux variation,

in which action the armature strikes and abuts Y armature comprising a plurality of laminations lying in planes substantially at right angles to .said surface or stop and' subsianiiaiiy' pmiiei to the movement for direct contact with the surface or stop" with their edge portions, means for holding said iaminations against each other with tension so that -they'norma'lly move as a'body; and means passing through the laminations transversely to the planes in which the laminations lie arranged to permit individual laminations to. shift in their plane's'relative to each other whereby individual laminationg may iust themselves individually to said surface or stop when attracted thereagalnst magnetically.

5'. An electromagnetic device comprising in combination a core having pole pieces, an armature, means mounting the armatin-e for bodily movement toward and away vfrom the core incident to magnetic ilux with the armature arranged to strike the pole pieces, said armature comprising a plurality of laminations 'disposed at right angles t the surfaces lof 'the poles which the armature is adapted to strike. means resiliently holding the ylaminations of the core together so that the individual lainlnations may shift relative to each other whereby individual laminations may directly contact with and adjust themselves in seating relation on the armature when the armature is in contact therewith.

CHARLES F.

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