US1799925A - Electric motor - Google Patents

Description

ELECTRI C MOTOR ori inal F le Dec- 15. 1922 mvzufon ATT N EY.

Patented Apr. 7, 1931 UNITED STATES, PATE NT. OFFICE ALFRED OSWALD, 0F HACKENSACK, NEW JERSEY, ASSIGNOB TO UNDEBWOOD ELLIOTT FISHER COMPANY, OF NEW YORK, N. Y., A CORPORATION 01 DELAWARE ELECTRIC MOTOR Original application filed December 18, 1922, Serial No. 606,575. Divided and this application filed November 24, 1926. Serial No. 150,592. Renewed October 10, 1928.

This invention relates primarily to motors which are alterable for use with either alternating or direct current, and to work in circuits having different fre uencies, etc.

The invention relates particularly to the construction of an annular field-magnet core for said motor. To facilitate the assembly or removal of pro-wound field-coils, the core consists of separable portions. Each coreportion is laminated and provision is made for uniform laminations or punchings for both cores.

Means for holding the two core-portions together may consist simply of a tight sleeve fitting around theassembled core-portions and pressing them firmly together in a direction substantially normal to the joints to secure a good magnetic bond at said joints. Besides the fact that the abutting surfaces of two core-portions are directly pressed together, that is to say, from diametrically opposite directions, to secure a good magnetic bond, said good bond is further assured because the core is made up of only two portions, that is to say, only two joints need be made, one joint at each pair of abutting legs of the semi-annular core-portions. To furthe: conduce to a good magnetic bond, each U-shaped punching may have a V-point or taper at the end of one extremity or leg, and a V -recess or socket on the other leg. In each core-portion every alternate punching may be reversed, so that, in the assembly, the points of each core-portion alternate with the recesses. The built-up halves of the magnet may then be assembled and form dovetailed joints, the points of each half fitting in the recess of the other half, and the joints overlapping, making an excellent magnetic joint, safeguarding the magnet against ordinary rough usage, preventing relative dis lace-' ment of the core-portions, and permitting the poles to approach closely to the armature with reduced liability of collision.

The use of acoreretaining casing or sleeve surrounding the core and holding its semiannular portions firmly together through pressure applied substantially from diametrically opposite-directions obviates the need for using bolts or similar devices passing transversely through the laminations to clamp the overlapping portions of laminations of the opposite core-halves together. While the latter method of clamping the core-halves together may secure a good magnetic joint, its application is apt to be unfeasible for some types of motors, as, for example, the motor herein shown, which, on account of its desired compact arrangement, afiords little or no room for such transverse fastenings. Y

Another feature of improvement relates to cleft pole-pieces of the fieldma net core, and to provision for placing the fiel -coils in such relation, to the cleft pole-pieces as to balance or take care of a'rmature reaction. This feature has a special benefit where the fieldcoils are to be connectible in either series, or parallel, or multiple series.

This application is a division of my application, Serial No. 606,575, filed December 13, 1922 (now Patent No. 1,713,617, dated May 21, 1929).

Other features and advantages will hereinafter appear.

In the accom anying drawings,

Figure 1 is a iagrammatic elevation of a motor embodying the present improvements in one form, the frame and certain parts being shown in section.

Figure 2 is a sectional elevation of the upper portion of a motor embodying certain of the improvements in another form, with the field coils placed directly upon the polepieces, instead of upon the necks of the field magnet as at Figure 1.

In order that the utility of the invention may be readil understood a brief description of the erein-shown motor will at this point be 'ven and will be followed by a description 0 the field-magnet core to which the invention particularly relates. It will be understood that the invention is not limited to the particular motor shown but may advantageously be applied to other types of motors.

The motor-shaft 40 carrying an armature 41 is journaled in bearings carried by the framework, which includes a barrel, drum or casing 46; said casing having the usual ends and advantages .cause serious sparking when the motor is used on direct current, the armature coils, short-circuited by said auxiliary brushes as they span ad a'cent commutator se ments, are caused to be in a weak field, so that the current induced in said last-mentioned armature coils and consequentlythe sparkin are minimized.- The opposite poles of the eldmagnet are therefore divided each by a cleft 58. Thus one pole includes parts 53 and 53" and the other pole includes parts 54: and 54. The armature coils short-circuited by auxilisry brushes 48 may be caused to pass the clefts 58 at the moment of said short-circuiting and thereby minimize sparking. Fieldcoils 49-52 are connectible in series, parallel, or seriesarallel in respect to each other but, in genera are in shunt relation to the arms.- ture. Auxiliary field-coils 66-73 are also connectible in various ways in respect to each other but, in general, are. in series relation to the armature and may oppose or assist coils 49-52.

For compacting the motor an annular field core shape is selected. All the field-coils are pre-wound, and the resent invention provides for easy assemb ing or removal of said coils upon or from said annular core, which is built 11 of laminationswhich ma be held together y rivets 61. To this en the annulus 55 is made in two parts, joined refer ably at what is suhstantiall a plane t rough the axis of the core, or, in ot er words, a lane midway between the opposite pole aces.

Thus each semi-annular core-portionis sub-,

stantially U shaped with the aforesaid cleft poles between extremities or legs 59 of the U.

'From Figure 1 it will be seen that the prewound field-coils may bereadily threaded over said legs of the semi-annular core-portions. The coils 49-52 surround necks 56 of the core, said necks joining the cleft pole parts to the legs 59. Said ole parts are oined by necks 57 forming t e middle portions of the semi-annular core-portions. The

' clefts 58 of the poles may be of such shape that a coil may be placed around the salient body of any one of the pole parts 53-53 or fi e-54, as indicated b the dotted line 60 (Fi re 1 said dotte line representing a fiel -coil in such position. Thus one coil may be placed around the neck 56 and an-.

other coil around the salient pole part to compensate for field distortion, and thereby conduce to uniform flux density across the pole faces in alternatin current operation. The auxiliary coils 66- 3 surround the legs 59 of the annulus. Figure 2 shows another form of annulus, in which the coils are all placed around the salient cleft picle parts no coil-receiving necks as 56 of igure 1 being provided.

The annulus is divided into only two portions so that only two oints need be made, a minimum for the number of joints to be made conducing to a good magnetic circuit. Dividing and oining the core at a plane throu h the core-axis makes possible the use of uniformlaminations or punchings. The laminations of the opposite core-portions may overlap at the joints 62, such overlapping being affected, while still providing for uniformity of the punchings, by having the end of one leg of each U-shaped punching extend beyond the plane at which the corehalves are nominally joined while the extent of the other leg falls correspondingly short of said plane. Thus, by reversing the punchings, a short leg abuts along leg in each pair of punchings which form the completed annular lamination. The aforesaid overlapping of the opposite core-laminations is then effected by reversing alternate pairs or groups of pairs of laminations. c

The shapes of theends of the legs may be made so as to effect interlocking of the pairs of laminations transversely of the motoraxis. The shape of the end of one leg of each punching is therefore referably in the form of a V or taper 62, w ile the shape of the other leg-end'is that of a V-recess or socket 62".

Inasmuch as the joints of the magnet-coreportions are surrounded by coils 66, 73, it is unfeasibl'e to fasten the two built-u coreportions together by means of bolts t rough the overlapping portions of the laminae. The motor-casing 46 is therefore resorted to as a means for holding the two core-portions together. By making said casing a tight sleeve fitting over the annulus, as indicated at 63, the portions of said annulus are forced together from diametrically opposite directions so that they are rigidly held and cause the end-surfaces of the opposite leg-members 59 to firmly abut and thereby form two good magnetic bonds. Interlocking means between the annulus and casing may be provided to insure against their relative rotation. Keepers 75, which complete a magsplitting said sleeve to permit its expansion and contraction for facilitating insertion of the core and for positive clamping of the same.

Variations may be resorted to within'the scope of the invention, and portions of the im rovements may be used without others.

aving thus described my invention, 1 claim:

1. In an electric motor including a series of pre-Wound field-coils, the combination of substantially semi-annular or U-shaped halfcores, the leg-members of each thereof abutting the leg-members of the other, said leg members surrounded by said pro-wound coils, and means to fasten said half-cores rigidly together in said abutting relation to form two satisfactory magnetic bonds, one at each of the abutments, said fastening meansinclucling a fastening sleeve fitted around said halfcores and forcing them together in diametrically opposite directions to form a complete built-up annular laminated magnetic core, each half-core being formed of U-shaped laminations, each of which is integral, said legs surrounding the armature of the motor.

2. In an electric motor including a series of pro-wound field-coils, the combination of substantially semi-annular or U-shaped halfcores, the leg-members of each thereof abutting the leg-members of the other, said legmembers surrounded by said pre-wound coils, and means to fasten said half-cores rigidly together in said abutting relation to form two satisfactory magnetic bonds, one at eachof the abutments, said fastening means including a fastening sleeve fitted around said halfcores and forcing them together in diametrically opposite directions to form a complete built-up annular laminated magnetic core, each half-core being formed of U-shaped laminations, each of which is integral, said legs surrounding the armature of the motor, the four legs of said half-cores being formed to interlock end to end.

3. In an electric motor including a series of pre-wound field-coils,'the combination of substantially semi-annular or U-shaped halfcores, the leg-members of each thereof abutting the leg-inembers of the other, said leg members surrounded by said pro-wound coils, and means to fasten said half-cores rigidly together in said abutting relation to form two satisfactory magnetic bonds, one at each of the abutments, said fastening means including a fastening sleeve fitted around said half-cores and forcing them together in diametrically opposite directionsto form a complete built-up annular laminated magnetic core, each half-core being formed of U-shaped laminations, each of which is integral, said le s surrounding the armature of the motor, t e legs of each of" said half-laminations being formed with co operative tapering and socket ends to effect interlocking of each half-lamination with its mate.

4. In an electric motor including a series ing a fastening sleeve fitted around said halfcores and forcing them together in diametrically opposite directions to form a complete built-up annular laminated magnetic core, each half-core being formed of U-shaped laminations, each of which is integral, said legs surrounding the armature of the motor, the legs of each of said half-laminations being formed with co-operative tapering and socket ends to effect interlocking of each halflamination with its mat-e, each half-lamination having one leg formed with a tapered point, and the other leg with a socket point to match, whereby both of said half-cores are built up of duplicate laminations throughout, the laminations in one half-core being reversed relatively to those in the other halfcore, so that the points of each half-core are set into the sockets of the other half-core.

5. In an electric motor including a series of pro-wound field-coils, the combination of sub stantially semi-annular or U-shaped halfcores, the leg-members of each thereof abutting the leg-members of the other, said legmembers surrounded by said pro-wound coils, and means to fasten said half-'coresrigidly together in said abutting relation to form two satisfactory magnetic bonds, one at each of the abutments, said fastening means including a fastening sleeve fitted around said halfcores and forcing them together in diametrically opposite chrections to form a complete build-up annular laminated ma etic core, each half-core being formed 0 U-shaped laminations, each of which is integral, said legs surrounding the armature of the motor, the legs of each of said half-laminations being formed with cooperative tapering and socket ends to effect interlocking of each halflamination with its mate, each half-laminapoint, rind the other leg with a socket point to match, whereby both of said half-cores are built up of duplicate laminations throughout, the laminations in one half-core be'n reversed relatively to those in the other halfcore, so that the points of each half-core are set into the sockets of the other half-core, the laminations of each half-core being alternatel reversed to effect overlapping joints throughout the magnet.

tion having one leg formed with a tapered 6. In an electric motor, a field-structure 1- ing of semi-annular or U-shaped half-portions joined at substantially a plane through the axis of said core, the joints being formed by means of corresponding taper and socket formations at the ends of the several laminations, each half-portion having a cleft pole, each part of said cleft pole being joined to one leg of the U by a coil-receiving neck or loop onto which a pie-wound coil may he slipped by threading it over said leg, each part of the cleft pole being so formed that the salient body thereof formed between the cleft and the aforesaid loop may also receive a pre wound coil, and core-retaining means where- 15 by said half-portions are embraced and pressure is applied at said ]Ol!1l3S to form a satisfactory magnetic bond, said pressure being substantially perpendicular to the aforesaid plane at which the core-portions are joined. 7. An annular field-magnet core built up solely of alternately reversed duplicate semiannular or U-shaped laminations, said laminations forming built-up U-shaped halfcores, which may be separated from each 25 other to thread pre-wound coils over the legs thereof, said half-cores being joined to form the complete annulus, in which the leg-ends of one-half portion abut the legends of the opposite half-portion, at their edges, means 39 for maintaining the edges of thelaminations together under pressure by applying a force I perpendicularly to the plane of separation between the half-cores, each annular lamination consisting of duplicate abutting U-shaped 5 parts, the legs of the U-shaped laminations having their abutting tips formed with protruding extensions and corresponding recesses, said extensions and recesses matching and interlocking by reason of the reversing of the U-shaped laminations one in respect to the other.

8. Field-magnet as set forth in claim 7, in which alternate annular laminations are also bodily reversed, so that the leg-extensions of adjacent annular laminations overlap and form a satisfactory magnetic bond.

ALFRED E. OSWALD.

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