US2081800A - Magneto-electric generator - Google Patents

Description

y 1937- LE ROY s. DUNHAM ET AL 2,081,800

MAGNETOrELECTRI C GENERATOR Filed June 14, 1955 2 SheetsSheet l IIIIIIIWIEIIIIIII IN V EN TORS Ze Pay. 6". Dun/7am.

'AT a lllll ll y 1937. LE ROY s. DUNHAM ET AL 2,081,800 I MAGNETO-ELECTRI C GENERATOR 2 Sheets-Sheet 2 Filed June 14, 1935 Patented May 25, 1937 UNITED STATES PATENT OFFICE MAGNETO-ELECTRIC GENERATOR Application June 14, 1935, Serial No. 26,686 12 Claims. (01. 171-209) This invention relates'to the design of a mag neto electric generator especially adapted for furnishing ignition current for internal combustion engines.

In the early days of magneto ignition of both the low and high-tension type, machines were relatively large, utilizing heavy bar or horseshoe magnets which in some cases were doubled; that is to say, a plurality of heavy magnets were used one within the other. Such machines were both heavy and expensive, and the trend has been in later years to reduce the size and cost of the magneto, while increasing the operating efficiency. This has been accomplished by a better class of materials and better and more efficient manufacturing methods.

To further reduce the size of the magneto, it has heretofore been proposed to use a rotating magnet, but to make a small permanent magnet suitable for rotating inside of a field structure is a diflicult thing to do, because such small magnets are relatively inefllcient when made as they have been according to methods similar to those used in making magnets used externally on mag.- neto structures.

More or less recently, magnetic alloys have been proposed which possess-very high coercive force and are consequently wonderfully efficient magnets, but many of these materials cannot be rolled or drawn and fabricated the same as tungsten, cobalt and chromium steels which have been used in the past for making bar and horseshoe magnets for magnetos and other purposes. Furthermore, these new magneticalloys cannot be operated by ordinary lathe tools, but must be ground. Even in the case of alloys which can be fabricated by the usual methods, the process is usually difiicult.

Our invention is therefore particularly directed to ways and means for utilizing these new magnetic alloys in such a way that a small but highly efficient rotating magneto may be constructed. Since these new magnetic alloys, such as a combination of nickel, aluminum and iron, are expensive at the present time, the size of the rotating magnet must be kept within material cost bounds, so thatthe total cost of the magneto can be held to a minimum.

Our improvement in magneto construction will be readily understood by reference to the annexed drawings wherein:

Figure 1 is a diagrammatic sectional view through a two-pole magneto on the line l-l of Figure 2.

Figure 2 is a section on the line 22 of Figure 1.

Figure 2a is a fragmentary view of a modified form of supporting the rotary magnet from that shown in Figure 2.

Figure 3 is a section similar to the lower portion of Figure 2, but showing a modified form of construction.

Figure 4 is an elevational view of the magneto rotor, the magnet being provided with laminated pole shoes.

Figure 5 is a section on the line 5-5 of Figure 4.

Figure 6 shows a modified form of rotor in which the magnet is solid, the shaft ends being attached directly to the end plates used for binding the laminations on the magnet pole shoes.

' Figure '7 is an end view of Figure 6.

Figure 8 is a view similar to Figure l but showinto a four-pole magneto.

Figure 9 shows the application of the invention to a six-pole magneto.

Figure 10 is a view on the line Ill-l0 of Figure 9.

Figure 11 is a view on the line lI-H of Figure 9.

Figure 12 is a section on the line l2-l2 of Figure 11.

Figure 13 is a view on the line I 3-I3 of Figure 11.

Figure 14 is a view on the line |4-l4 of Figure 15, showing an alternative method of fastening the laminated pole shoes to the poles of the rotary magnet.

Figure 15 is a section on the line I5l5 of Figure 14.

In the various views, wherein like numbers refer to corresponding parts, I is a rotor constructed of a magnetic alloy such as a compositi on of nickel, aluminum and iron, made by forming the material to substantially the desired shape. By forming we mean casting in a suitable mould or compressing material in a die or the like. The rotor has a, hole 2 therethrough and oppositely disposed recesses 3 and 4 which extend longitudinally of the magnet, leaving pole areas N and S. The rotor l is cast or moulded with oppositely disposed projecting hubs 5 and 6 which in our process are ground to a sizeto receive recessed shaft portions 1 and 8 in the shaft ends 9 and I0. It is obvious that a reverse arrangement can be used; that is, the magnet hub may be internally ground to fit over the shaft end. In the assembly of the rotor with the shaft ends as shown in Figure 2, one shaft end, for

example 9, is internally threaded to receive a relatively small stud I I which is securely screwed into the shaft end 9, after which the rotor I is put into position and the shaft end I II is then screwed home onto the opposite end of the rod I I.

To prevent rotary displacement between the rotor I and the shaft ends 9 and II), the hub portions 5 and 6 have key-ways ground therein and the overlapping portions of the shafts 9 and I0 are indented thereinto as indicated at I2 in Figure 5. After the assembly has been completed, the rotor structure may be mounted on the shafts 8 and I0 and the periphery of the magnet ground to the size to fit within the field structure composed of pole pieces I3 and I4, carrying a yoke II and a coil I6. In the two-pole structure such as illustrated in Figure 1, it is readily seen that the magneto will deliver two sparks per revolution of the rotating magnet.

In Figure 211 we have shown a modified form of construction in which the projecting hubs 5 and 6 of the magnet are ground at an angle and the overlapping portions I! of the shafts 9 and III are forced over the portion 5, making a dovetail fit, whereby the shafts 9 and III are prevented from pulling off the magnet longitudinally, rotary motion being prevented as illustrated by the construction shown in Figure 5 and heretofore described.

In Figure 3 we have shown a further modified method of assembling the magnet I with the shaft ends 9 and III. In this construction the shaft 9 has an integral extension III, onto which the shaft I0 is threaded, the shoulder 5 of the magnet fitting within an annular recess I 9 in the shaft 9. In this construction, relative rotary motion between the shafts 9 and I0 and the magnet I is prevented in some manner such as heretofore described with resp ct to Figure 5.

In Figures 1, 2 and 3, the construction utilizes the magnet substantially as formed, with the exception of the grinding operations referred to, but we have found that the efficiency of the magneto may be somewhat improved by adding polar surfaces composed of suitable laminated magnetic material. Such polar additions are illustrated in Figures 4 and 5. In this construction the magnet I is cast, moulded or extruded with the edges 20 and 2I of the poles N and S inclined slightly in pairs toward each other. The laminations 22 are stacked on rods 23 and then the stack is forced over the inclined or tapered surfaces 20 and 2I, after which the end plates or thicker laminations 24 and 25 are put in position. However, we have found it preferable to arrange the holes in the laminations 24 and 25 slightly closer together than the holes in the inner or thin laminations 22, so as to more securely bind the laminations to the magnet I. After assembly of the laminations Just described has been completed, the rods 23 are upset or riveted so as to complete the assembly operation.

In many cases the cost of these auxiliary laminated pole shoes is not justified and they may be omitted where low cost is required and the full degree of efiiciency of the magnet is not necessary.

In Figures 6 and 7 we have shown a different manner of attaching the shafts 9 and III to the magnet. In this form of construction the end plates 24 and 25 are made thicker than shown in Figure 4, and the shafts 9 and III are provided with integral flanges 26 and 21 which are riveted or spot-welded, or otherwise securely fastened to the end binding plates 24 and 25, By

using the solid magnet, the efilciency of the same is improved and when this structure is used with the laminated pole shoes as indicated in Fig ures 6 and 7, the highest degree of efficiency of such a magnet is attained.

So far we have shown and described a magneto which is capable of delivering two sparks per revolution. In Figure 8 we have shown the magnet I having four magnetic poles operating with the field structure similar to that shown in Figure l, but which gives four sparks per revolution, although only two of the poles are working at one time. However, this may be obviated by using a magnetic collector system along the lines of that shown in Figures 9 to 13 inclusive.

In Figure 9 the magnet is provided with six magnetic poles with flux collectors, so that all of the poles are working simultaneously to produce six sparks per revolution. One of these flux collectors, in the form of a spider 28, is shown in Figure 12, while the other, 29, is shown in Figure 13.

As shown by Figures 9 to 13 inclusive, the laminated field pole shoes 28a and 29a are cast integral with the frame 30. Likewise, in Figure 9, the field pole pieces, running from the coil core I5, are preferably cast integral with the housing 30 and, as will be seen from Figure 9, they are in contact with one side of a pair of the pole pieces 28a and 29a. After the housing 30 with the pole pieces has been completed, the spiders 28 and 29, made of laminated stock, are forced into their position at opposite ends of the housing 30, after first inserting the magnet I having the shaft ends attached thereto as previously described.

By utilizing a construction such as shown in Figures 9 to 13 inclusive, we have reduced the size of the magneto materially, yet at the same time, we have increased the efficiency of the magneto by reason of the fact that the length of the magnetic circuits have been reduced to a minimum and by reason of the further fact that we have provided a structure which will simultaneously have a plurality of magnetic poles included in a magnetic circuit with the rotor. Because of the high efiiciency of these new magnetic alloys, the number of poles in the rotor may be made in any suitable number to meet the requirements of the engine with which the magneto is to be used.

Figures 14 and 15 illustrate a different method of assembling the pole shoes or tips on the ends of the magnet poles. The laminations 22 are cut to shape to fit over the polar ends N and S of the magnet and to be forced into engagement with tapered surfaces 20 and 2I. The tapered surfaces of the laminations are cut at a different and wider angle than those on the magnet, as shown by dotted lines, whereby the laminations may be readily applied to the magnet. The laminations 22 are stacked on rods or rivets 23 and the stack is slipped over the magnet polar end. Pressure is then applied to the projecting ears of the lamination stack to cause the inside surfaces thereof to come into firm engagement with magnet surfaces 20 and 2 I. Simultaneously and automatically, the laminations are brought into firm engagement with the end of the magnet. We prefer to make the outer members 24 and 25 of the lamination stack thicker than the rest and also to make them larger in area, whereby they overlap the magnet toward its axial center to prevent lateral displacement of the stack. ,The whole assembly is made fast by riveting over the rods 23.

While we have shown the spiders 28 and 29 as contacting with the inner surface ends of the magnetic pole shoes 28a and 29a, they may contact with the extreme ends thereof without increasing the diameter of the casing 30 carrying the members 28 and 29.

What we claim is:

1. In a magneto electric generator having a relatively stationary system including a coil and members of magnetic material for gathering and sending magnetic flux therethrough, a rotary permanent magnet for supplying magnetic flux to said system, said magnet being made with hubs at each end and spaced recesses forming poles, the magnet having shaft ends fastened to said hubs, and pole shoe pieces fastened to said poles.

2. In a magneto electric generator having a relatively stationary system including a coil and members of magnetic material for gathering and sending magnetic flux therethrough, a rotary permanent magnet for supplying magnetic flux to said system, said magnet being made with hubs at each end and spaced recesses forming poles, the magnet being hollow and having a stud located in said hollow, said stud being threaded at both ends, and a stub-shaft screwed to each end of the stud and having an annular recess fitting over said magnet hubs and anchored thereto.

3. In a magneto electric generator having a permanently magnetic rotor as a source of magnetic flux, said rotor having a plurality of poles of opposite polarity, a magnetic flux collecting system disposed as a cage surrounding said rotor, said cage consisting of members of magnetic material equal in number to the number of poles of the rotor, said members extending in lines parallel to the axis of rotation of the rotor and spaced apart about the rotor in cylindrical formation whereby magnetic cooperation will occur between said members and the poles of said rotor when the latter is turned about its axis, said cage being completed by magnetic end portions positioned adjacent each axial terminus of said rotor, one of said end portions connecting alternate members of the cage at one end and the other of said end portions connecting the remaining cage members at the opposite end; a coil core of magnetic material, magnetic flux conveying members connecting opposite ends of said core to two of the adjacently spaced cage members of magnetic material, and'an induction coil on said core.

4. In a magneto electric generator having a permanently magnetic rotor as a source of magnetic flux, said rotor having a plurality of alternate opposite poles; a magnetic flux collecting system comprising a cage having members of magnetic material surrounding said rotor, said cage consisting of two portions disposed in intermeshed digital relation to each other and in coaxial enclosing cylindrical relationship with respect to said rotor, each of said portions consisting of spaced members to the number of onehalf the number of poles on the rotor, whereby all the poles of the rotor act simultaneously to send flux lines into these spaced cage members which extend in lines parallel to the axis of the rotor and an end member magnetically connecting said spaced members; a coil core of magnetic material bridging the said two cage portions through two of said cage members and generating windings associated with said core whereby electrical currents are generated in said windings by the rotation of said rotor within said cage.

5. In a magneto electric generator, a rotor comprising a single-piece permanent magnet having a series of poles of opposite polarity, a stator including a cage for the rotor composed of members equal in number to the poles of the rotary magnet and spaced according to the magnet pole spacing and spiders of magnetic material having portions contacting with the inner surfaces of the ends of alternate cage members adjacent opposite ends of the rotor, a coil and core therefor with core pieces extending from opposite ends of the core into contact with two alternate cage members.

6. A magneto electric generator as set forth in claim 5, further characterized in that said coil core pieces contact with the two nearest cage members.

7. A magneto electric generator as set forth in claim 5, further characterized in that said spiders are materially smaller in interior diameter than the rotor and have armsextending into contact with the interior surfaces of the ends of the said cage members.

8. A structure for the generation of electric current including, a hollow frame having a plurality of members of magnetic material spaced around the inner periphery thereof, said frame also carrying at opposite ends thereof a spider of magnetic material having portions contacting with the inner surfaces of the ends of alternate ones of said members, a pair of core pieces extending one each from adjacent top ones of said members, a coil core spanning said core pieces, a generating winding on said core and a rotor of magnetic material operatively positioned within the frame to direct magnetic flux through said members carried by the frame, the core pieces and coil core.

9. A structure for the generation of electric current as set forth in claim 8, further characterized in that the rotor has poles in number corresponding to said members of magnetic material spaced around the hollow portion of the frame.

10. In a magneto electric generator, a rotor comprising a permanent magnet having a series of poles of opposite polarity, a stator including a cage for the rotor composed of members equal in number to the poles of the rotary magnet and spaced according to the magnet pole spacing and spiders of magnetic material having portions contacting with alternate cage members at opposite ends of the rotor and at points within the outer boundary of said cage members, a coil and core therefor with core pieces extending from opposite ends of the core into contact with two adjacently positioned cage members.

11. In a magneto electric generator having a relatively stationary system including a coil and members of magnetic material for gathering and sending magnetic flux therethrough, a rotary permanent magnet for supplying magnetic flux to said system, said magnet being made with hubs at each end and spaced recesses forming poles, the magnet having shaft ends fastened to said hubs.

12. In a magneto electric generator having a relativelystationary system including a coil and members of magnetic material for gathering and sending magnetic flux therethrough, a rotary permanent magnet for supplying magnetic flux to said system, said magnet being made with magnet hub, a part of said engaging portion being hubs at each end with at least one recess therein, indented into its hub recess to prevent relative and spaced recesses forming poles, the magnet rotary motion between the magnet and the shalt being hollow and having a stud located in said end.

hollow, said stud being threaded at both ends, LE ROY S. DUNHAM.

and a stub-shaft screwed to each end of the stud ARTHUR F. ROBERTSON. and having a portion engaging its cooperative

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