US2213724A - Magneto rotor - Google Patents

Description

Sept. 3, 1940. E A, VQGEL 2,213,724

MAGNETO ROTOR Filed May 12, 1938 2 Sheets-Sheet l EDWARD VOGEL ATTORNEY Sept. 3, 1940. 5 VOGEL 2,213,724

MAGNETO ROTOR Filed May 12, 1938 2 Sheets-Sheet 2 INVENTOR EDWARD A VOGEL @zmzw ATTORNEY Patented Sept. 3, 1940 UNITED STATES MAGNETOO mon Edward A. vogel, Beloit, Wis, assignmto Fair-.- banks, Morse 8: (30., Chicago, 11L, a'corporation of Illinois Application May 12, 1938, Serial No. 207,548

1 Claim.

This invention relates to improvements in magneto rotors and involves a rotor wherein the magnetomotive force is-produced by a magnetic alloy composed chiefly of aluminum, nickel and cobalt. Such alloy may be formed into permanent magnets having very high unit coercive force, and for this reason is especially suitable for use in the construction of magnetos for ignition purposes where a small, compact, yet

l0 highly powerful magneto is desired. Alloys of the character referred to are extremely hard and brittle, and in general cannot be subjected to the usual machining operations, grinding being practically the only satisfactory method of opcrating on this type of alloy.

The principal object of the invention is to provide an improved magneto rotor construction utilizing an alloy of the aluminum, nickel and cobalt variety for the permanent magnets, the

improvements being directed to simplification of manufacture, reduction of cost, and decreas ing the size of rotors without impairing their operating efhciency or magnetic output.

Another object is attained in the provision of an improved rotor having relatively few component parts which are integrally connected in the formation of a rigid, unitary structure without the use of bolts, rivets or like securing means.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. lis a side elevation of a bi-polarrotor constructed in accordance with nrv invention; Fig. 2 is a sectional side elevation of the rotor of Fig. 1; Fig. 3 is an end view of therotor of Fig. 1; Fig. 4 is a transverse sectional view, the

section being taken at line 44 of Fig. 2; Fig.5; 4 is a transverse sectional view of a six pole rotor constructed in accordance with my invention;'

Fig; 6 is a sectional side elevation of a rotor of modified form; Fig. 7 is a transverse section of the rotor of Fig. 6, taken atline 1- of that figure; Fig. 8 is a longitudinal section taken at line 8-8 of Fig. 7, and Fig. 9 is a perspective view of a laminated pole shoe employed in the rotor construction of Fig. 6.

Referring now by characters of reference to Figs. 1 to 6 of the drawings, there is illustrated a one-piece shaft 6 of suitable diameter to provide adequate bearing surfaces which are indicated at I. A length of the shaft between the bearing surfaces 1 maybe f reduced diameter as shown, and is'characterized by an intermediate portion 8 offluted or angulate configuration which is adaptedto receiveand interlock with a surrounding body of molded, non-magnetic material S. In other respects shaft 6 may be of conventional form. The magnetic member of the rotor, indicated generally at I0, is formed of an alloy of aluminum, nickel and cobalt, an alloy suitable for the purpose being .known and currently available under the name of Alnico steel. It is to be understood, however, that any suitable alloy of high coercive magnetic characteristics may be used. The member M has the general form of a relatively thick-walled ring or tube, and is given its ultimate shape by casting in a suitable mold, or by compressing the ma- 35 terial thereof in a.suitable die. Member ID- is initially formed with diametrically disposed recesses H which extend the full length of the member and define salient polar portions l2 and 13. A central longitudinal bore [4 in member 20 communicates laterally with undercut or dovetail recesses 55, the recesses being located in radial alignment with the polar portions l2, l3. Such disposition of recesses i5 is desirable because the electrical output of the magneto, and 25' hence the strength of the ignition spark produced thereby, is directly proportioned to the cross-sectional I area of the neck portions i6 connecting adjacent poles. It will appear that by arranging the recesses it with respect to the 30 polar projections as aforesaid, the cross-sec tional area of neck portions l6 is not diminished.

In assembling the rotor, the shaft 6 and magnet member are suitably positionedin the relation of their final assembly in a die-casting 35 mold and the material which makes up the body 9, in molten or plastic condition, is introduced into the mold to fill completely the space between the shaft and magnet member, and to extend over the ends of the magnet member as 40 indicated at it. My preference is to utilize. aluminum or zinc for the body, material 9, although any suitable non-magnetic material such as Bakelite may be employed. It will appear that the body 9 interlocks with the magnet mem- 45 chined, if necessary, to attain the desired amount of axial clearance between the rotor and bearing races.

After the body material has become set, the rotor is removed from the assembly mold and the peripheral surfaces if! 'of the poles are ground to render them smooth and true. The member ID is then placed in a magnetic circuit of high intensity to cause the member to become permanently magnetized.

The efficiency of rotors of the general construction illustrated in Figs. 2 and 4 may be improved at small additional manufacturing cost by the provision thereon of laminated pole shoes. Figs. 6 and 9 illustrate the preferred construction and assembly arrangement of a two-pole rotor. thusly modified, the same being described as follows:

The magnetic body member 2b is molded of alu- -minum-nickel-cobalt alloy, as previously explained, in the form of a relatively thick-walled tube having underecut recesses 28 cylindrical surface of member 28. The arcuate faces 2 of portions 22- are rendered smooth and true, as by grinding, in order to make good surface pole shoes 25.

The pole shoes 25 as provided, consist of stacks of sheet steel laminations 26, each of a generally arcuate shape. The opposite end edges 2? of the .laminations slope inwardly from their outer peripheral margin 28 to meet the upper edge of projecting portions 29, in theformation of a recess or shoulder 3%. In assembly, the inner peripheral margins 3i of the laminations seat upon the arcuate faces 26 of member 2% and the end projections 29 extend into grooves 23. Semi-circular recesses 32 formed in the lateral edges of projections 29 define grooves or seats for receiving fastening elements 33 which serve to hold the laminations togetherin perfect alignment after assembly thereof in the formation of the pole. shoes. The ends of elements 33 are bent or crimped over the sides of the end laminations as best appears from Fig.9, so as to exert a clamping force which compresses and holds the laminations together in assembled relation. The pole shoes thus described, together with a shaft 35 which, in all essential respects may be identical to the shaft described in connection with the rotor of Fig. 1, are arranged with the magnet member 29 in the positions of their final assembly in a suitable die a casting mold.

1 and magnetic body, serving to lock these members together; annular discs 31 that embrace the end surfaces of the magnet body and pole shoes; and bridge portions 38 of arcuate section that extend circumferentially between the pole shoes. As best appears from Fig. 7, portions 38 extend laterally about the pole shoe projections 29 in overlapping relation with the shoulders 39 thereof, serving to hold the pole shoes rigidly and tightly against the pole portions of the magnet body.

' Magnetization of the rotor is efiected after the described assembly process and is accomplished by subjecting the same to a high intensity magnetic field.

Having described my invention, what I claimand. desire to secure by Letters Patent is:

In a magneto rotor, a magnetof tubular form having longitudinally extending grooves spaced circumferentially? about its outer surface defining polar portions of the magnet, and under-cut recesses extending from its inner surface into the said polar portions, pole shoes of generally arcuate formseated on said polar portions, said pole shoes comprising stacked laminations having longitu dinally and laterally ofi -set end projections extending into said magnet grooves, and U-shaped clamping elements embracing said end projections and uniting the laminations, during assembly; a shaft having an intermediate portion of reduced diameterspaced centrally within the magnet, said shaft having longitudinal recesses formed in its reduced portion; and an integral body of non-magnetic metal die-cast in place about the magnet and serving to unite the shaft, magnet and pole shoes, said body comprising a sleeve portion'completely filling the space between the shaft and magnet, layer portions covering the outer surface of the magnet between the pole shoes, said layer portions extending over said end projections of the pole shoe laminations whereby to lock them individually to the mag net, and disc portions embracing the opposite end faces of the magnet and pole shoes and interconnecting said sleeve and layer portions of the nonmagnetic body.

EDWARD A. VOGEL.

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