US 917138 A
Description (OCR text may contain errors)
APPLIOATION FILED Jule, 1907.
917,138. Patented Apr. 6, 1909.
KIWI/$ 55555 NYE/V705 k W' ZZZ YI/IZAY 5/75/51 ATTY.
Norms I'EIERs. INC LiYHuH WASPHNOH-N, D c
UNITED STATES PATENT OFFICE.-
CONWAY ROBINSON, OE'SCHENECTADY, NEW YORK, ASSIGNOR; TO GENERAL ELECTRIC" COMPANY, A CORPORATION OF NEW; YORK.
m5. 9 mice.
. Specification of Letters Patent.
To all whom it'may concern:
Be it known that I, CONWAY ROBINSON, a
citizen of the United States, residing at- Schenectady, county of Schenectady, State of New. York, have invented certain new and "useful Improvements in Magnetic Wedges, of? which the following is a specification.
My invention relates to dynamo-electric machines and particularly to wed e devices for retaining conductors in: slots ormed in the core structures, and it has for its object to improve such devices.
In the stators of induction. motors, par.-
ti'cularly, it-is of ad'vant'ageto have the surface 'of the core present, as nearly as possible an unbroken area of magnetic material to effect a uniform'di'stribution of the flux and decrease'the reluctance of the air gap.
.It is also desirable in this and other types of dynamo-electric machines to bring the condiictors as near the surfaceas possible in order-to reduce the length of the magnetic circuits toa minimum. The retaining wedge should therefore be preferably formed in part, at least, of magnetic material, and shouldbe mechanically strong in order that it may be made as thin as possible and thereby permit the conductor-receivingslot to be made only slightly deeper than the depth of the conductors. It is also, of course,.necessary to divide the magnetic material 'of the wedge or retaining device in such a waythat no eddy currents are set up therein.-
M'y invention therefore consists in a novel construction and arrangement of parts constituting a wedge having the above and.
other-desirable characteristics. The various features of novelty w1ll be pointed out withparticularity in the appended claims; but for a full understanding of" he invention and of its various objects and. advantages reference may be had to the following detailed description taken in connection withthe accompanying drawing which shows a preferred embodiment.
Insaid drawing, Figure 1 shows a portion of" a dynamo-electric machine having the improved retaining device applied to the armature or rotor thereof; Fig. 2 1s a per- Vsipective view of a section of a retaining vice; Fig. 3 is an enlarged view showing in'cross-section a set of conductors arranged in a slot with the retaining dev ce in position; and Fig. 4 shows a portion of an 1ndu ction motor having the retaining devices applied tothe stator.
Reference being had to the drawin A.
indicates the improved" wedge as a w ole.
It is madein such form. that when in positionit partially bridgesthe slot with mag: netic material'so as to form a pole tip or tips adjacent the slot. It may conveniently be made in the form of a pair; of magnetic strips land 2, secured or cemented to a back ing 3', which is preferably made of. fiber on some other tough material, adding to the strength of the wedge and at the same time providing a. certain elasticity whereby. the
wedge may readily adjust itself to the slot into which it is driven. The members 1 h and 2'are preferably of subdivided magnetic material so as to avoid eddy losses. "For thls purpose iron-wool, or iron filings, held together by some suitable electrically nonrthe transverse direction. The member 3 may conveniently be made of'wood pul'p, asbest-os or some other fiber also held together by a suitable binder. I have found. that sodiuni silicate may be used to advantage as the binder for the magnetic material, and" gelatin chromateas a binder for the fiber; These particular compositions need not necessarily be used, however.
The member 3 preferably takes theshape of a slightly curved slab having a thin, and preferably tapered, central rib 4 projecting from one side thereof. When made of some fibrous material held together by a suitable binder, it is preferably formedby'placing the plastic material in suit-able dies upon which suflicient pressure is exerted to squeeze the whole into a tough mass. This is then dried and placed in another die or mold having the shape of the completed wedge. The material of the magnetic portions is then introduced into this latter die or mold and pressure is again exerted until the magnetic portions together with, the slab of fibrous material are pressed and cemented into a hard. compact form. The whole is then dried, and, if desired,provid'ed with a coating of'varnish. The resulting wedge is exceedingly stifl and strong.
The rib on the member 3 is preferably of such lengththat its outer edge issubstantially flush With the upper surface of the magnetic portions 1 and 2 and the combined Widths of this rib and the magnetic portions (which is equal to the Width or". the slot into which the Wedge is to be driven), is somewhat less than the Width of the body portion of the member 3, \vherebybeads 5 and 6 are formed at the sides of the wedge by the projecting portions of the fiber backing.
T he manner of using the WGClQG is shown in Fig. 3, wherein 7 indicates a fragment of core having a coil-receiving slot 8. 9 and 10 are two coils arranged one above the other 'in the slot. The slotmay conveniently be made rectangular in form with a pair of under-cut grooves 11 and 12 on opposite sides thereof at points adjacent the top of the uppermost coil. These grooves are adapted to receive the beads 5 and 6 of the Wedge. The parts are so proportioned that the outer surface of the Wedge is flush With the outer surface of the core member.
It will be seen that the magnetic portions 1 'the Wedge to the other, and causes the flux to pass in the proper direction from each pole-tip down into the core body By making the bottom of the wedge curved, as shown, whereby it tits the upper surface of the conductor 9, an added depth is given to the Wedge Without necessitating an increase inthe depth of the slot as a- Whole. I v
Referring to Fig. 1, 13 indicates the field magnet, 0r stator, of a dynamo-electric machine, and 14 the armature, or rotor, which.
has a core 7 provided With slots8 forthe conductors 9 and 10. Eachsetof conductors, it- Will be seen, is held in place by one of the Wedge devices. p I
In Fig. 4.- I have shown an induction motor comprising stator and rotor n'ieinbers l5- and 16, respectively; the retaining devicesjit being used to hold the coils 17 and'18 in place.
In direct current machines, it is not necessary that the Wedges be magnetic'and in stead of iron or steel wool, copper WOOl may be employed to advantage.
While I have described in detail a preferred form of my invention, 1 do not desire to be limited to the particular arrangement, of parts shown since in its broader aspects my invention contemplates other.
constructions emlwdying the essential tea turcs a1 defined in the append d claims.
What 1 claim as new and desire to secure by Letters atom 01' the llnited States, is,-
1. As an article of manufacture, a slotclosing device consisting of a bar composed of" magnetic material whose continuity is inicrrnpted by portions of electrically nonconducting: material and a central layer ol' non-magnetic material dividing said bar into two portions, said bar and said central layer being cemented together.
2. As an article of manufacture, a slot closing device consisting of a bar composed cf linely divided portions of magnetic material held together by a binder of electriially non-conducting material, said bar having a central portion of non-magnetic material, said bar and said central portion being cemented together. As an article ofnninufacture, a'slot closingdevice consisting of strips composed of finely divided magnetic material held together by electrically non-conducting bindmg material, together with an interposed strip of non-magnetic material, said strips being cemented together.
i. As an article of manufacture, a slotclosing device consisting of a fiber backing having a projecting rib on one side and strips composed of finely divided portions of magnetic material held togetherby a binder of electrically non-conducting material, arranged on'opposite sides of said rib, said backing and said strips being ce merited together.
5. As an article of manufacture, a slotclosing-device consisting 01"- a fiber backing having a central rib on one side and a fillingof finely-divided magnetic material and electricallyv non-conducting binding mate rial on opposite sides of the rib, said fiber backing and said filling being cemented together.
6.';-\.s an article of manufacture, a slotclosing device consisting of a bar of mag netic material divided into two halves by a strip of non-magnetic material and backed by a layer of non-magneticmaterial which projects beyond the sides of the bar to form tips being separated by and cemented to a strip of nonmagnetic material. 7
8. Thecombination with a dynamo-electric machine having coil-retaining slots with grooves in the sides thereof andcoils in said slots, of slot-closing devices consist- ,ing each of a strip of non-magnetic material -tr1c machlne having coll retaining slots, of
concaved on its under side to fit the top of the coils and having projecting heads at the edges adjacent the concaved side fitting said grooves and portions of metal Wool cemented -to said strip.
9. As an-article of manufacture, -a slotclosing device consisting of a bar composed of metal wool held to ether by an electrically non-conducting binder.
10. As an article of manufacture, a slotvices each in the form of a pair of pole tips composed of magnetic-woohsaid tips being separated by and cemented to a strip of non-ma et'ic material.
- 12. T e combination with a dynamo-elecslot closing devices each consisting of a bar of metal Wool cemented to a strip of .nonmagnetic 1nateria1.
1E The combination With a dynamo-electric machine having coil retaining slots, of slot closing devices each consisting of a fiber backing, having a projecting rib on'one side and strips of'm'agnetic wool cemented to opposite sides of said rib.
14.-As an article of manufacture, a slot closing device consisting of a pair of pole tips composed of magnetic Wool separated by and cemented-to a strip of non-magnetic material.
In WVitIlGSS whereof, I have hereunto set my hand this 7th day of January, 1907.
BENJAMIN B. HULL, HELEN Onronn.