US2015091A - Magneto - Google Patents

Description

M. E. SPOHN Sept 24, 1935D M AGNET O 4 5 Sheets-Sheet l Filed Aug. 14,l 195 IUE@ l l l Sept. 24,` l1935. M. E. sPoHN 2,015,091

MAGNETO Filed Aug. 14, 1954 :s sheets-sheet 2 INVENTOR /V/uCo/.M E Spa/Anl ATTRNEYS Sept. 24, 1935. M ED SPQHN 2,015,091

*A MAGNETO Filed Aug. 14, 1934 5 Sheets-Sheet 5 m msrf rma/uffa /7/11. couv ipo/vw.

ATTORNEYS .40. of a`wide range of numbers of cylinders.

Patented Sept. 24,v 1935- UNITED STATES Massaro MalcolmE. spolm, Sidney, N. Y., signal-'to 'rile Spohn Corporation, Norwich, N. Y., a corporation of Delaware Application August 14, 1934, Serial No. 739,728

1s claims.' (c1. 11i-252) This invention relates to electrical generators of the magneto type, and particularly to magnetos designed primarily to furnish electrical energy for the ignition systems of internal combustion motors.

One of the most important fields of utility of magnetos in motor ignition systems is in the airplane motor eld. In this field it will be obvious that the utmost strength and durability of the magneto construction consistent with its required lightness must be combined with-absolute reliability of operation, the latter necessarily including uniformity and continuity of performance and practicable permanence of the magnets. l

Many solutions have been attempted 'of the problems of magneto design presented by the special requirements of airplane lmotor operation. Some of these attempted solutions have been successful to the extent that some of the special requirements of airplane moisi ignition systems have been met. However, meeting some of the special requirements others have not been met and in some cases4 these other requirements have only been emphasized by the attempted solutions.

One of the problems in the design of airplane motor ignition magnetos that has not heretofore been fully solved is to provide a simple, light, reliable magneto that can readily be adapted, without change in its fundamental design, for use as a single unit with motors of a considerable variety of numbers of cylinders, including motors having odd numbers of cylinders. A particular -object of the present invention, therefore, is to provide a magneto of simple, compact, light, strong and durable construction and of dependable eiciency and reliability in operation which, without change of its vfundamental design, can readily be adapted for use with airplane motors A further object of the invention is so to design an ignition magneto that, in adapting it to motors of different numbers of cylinders, increase in the weight of the magneto with increase in the number ofl cylinders with which it is to be used will be,relatively negligible. Contributing to thisv is the novel magnet and armature arrangement oi the present invention.

The invention aims further to provide an ignition magneto in which, regardless of the number of cylinders to be iired in the motor with which it is to be used, provision may readily be made, without marked increase in weight, either of the magneto or of the distributor, and without impairment of eiliciency, for delivering to each cylinder a plurality of sparks. The magneto may thus readily be adapted for use as the energy furnishing part of dual ignition systems such as are now usually employed with airplane and other high speed internal combustion motors 5 both to insure certainty of operation and also for increased emciency.' The invention even goes so far as to provide a magneto construction which may readily be adapted, without marked increase in weight, to provide even more than l0' dual ignition if that be found desirable.

Because of the commotion of the ordinary vmagneto, which usually does not develop lthe same number of sparking impulses per rotation of the rotor as there are`cylinders to be fired in l5 the motor with which it is used, it has been necessary heretofore to provide for different speeds of the distributor and magneto, thus necessitating the use of considerable gearing. Moreover, the resultant high magneto speeds have tended to cause heating, bearing trouble, flattening out of the spark intensity, etc. One of the principal objects of the present invention, therefore, is to provide a magneto in which the rotor part may run at half engine speed, thereby reducing the tendency to heating, etc., and at the same time permitting the magneto rotor and the distribu tor to be driven from the same shaft, thus elim.'- inating both considerable gearing and the bearings therefor. The invention aims alsoto provide a magneto, preferably of the type in which the permanent magnets are carried by the rotor, 4which may operate at one-half the speed of the motor withwhich it is associated but which, nevertheless,

by reason of the peripheral speed of its inductive elements will compare favorably with magnetos of greater axial speeds when it comes to motor starting.

In designing a magneto todrun at one-half the 40 speed of the motor with which it is to be used, it is practically essential that the magneto fur; nish as many sparking impulses as there are ymotor cylinders. To this end the present invention contemplates the provision of as many localized fields of induction, represented by individual magnets in the magnetcarrying rotor, as there are motor cylinders.

In order, however, that the mass of each individualmagnet in a construction of this sort need notvbe so great, the invention aims to reinforce the inductive effort of each magnet by such con'- nection to the other magnets which are not in direct inductive relation to the stator coil core that there will be a' considerable concentration of 55 magnetic lines of force where they are needed. To this end the invention aims so to arrange the magnets on the rotor and the cooperating poles of the stator coil core that the stator will complete a separate or localized magnetic circuit with each magnet as the magnets move in succession past the stator and that this inductive action will be reinforced by magnetic connection of the respective poles of each magnet to the corresponding poles of other magnets of the rotor.

An important novel feature of the invention is the arrangement of the individual magnets v so that their poles are spaced lengthwise of the axis of the rotor and that all like poles are at the same end of the rotor and are all magnetically connected to each other. By this arrangement a maximum inductive effort at each localized held of induction is obtained and a construction of the rotor is obtained whichadapts itself more readily to use with motors having odd numbers of cylinders.

Another important feature of the invention is the novel spark adjusting means which insures a spark of the same degree of intensity both in advanced position and in retarded position.

Other objects of the invention and important novel features of its construction and mode of operation will appear from the following description and claims when considered in connection with the accompanying drawings in which* Figure 1 is a vertical section through a magneto embodying the `present invention, this magneto having also assembled therewith the interrupter and distributor;

Figure 2 is a section on the line 2--2 of Figure l and shows details of the retarding mechanism;

Figure 3 is a plan view looking from above with a portion of the distributor housing broken away;

Figure 4 is a section on the line 4 4 of Figure 1 and illustrates particularly the interrupter;

Figure 5 is a section on the line 5-5 of Figure 1';

Figure 6 is a detail view of one of the laminae of the magnet pole shoes, and

Figure 7 is a wiring diagram.

. In the illustrative embodiment of the invention the rotor of the novel and improved magneto construction comprises a plurality of magnets 2 of bar or rodlike form. spaced at uniform radial.

distances from the rotor shaft 4 and at uniform angular distances about the shaft 4.

In the illustrated construction nine of these magnets 2 are provided for a nine cylinder motor. A11 of the magnets 2 are arranged with their like poles at the same end of the rotor, that is, with their north poles at one end of the rotor and their south poles at the other end of the rotor, and in the preferred embodiment of the invention the poles at the respective ends of the rotor are magnetically connected. The illustrated means for effecting magnetic connection of the like magnetic poles at the respective ends of the rotor comprise rings of soft iron or steel 6 and 8 connecting the poles at the upper end of the rotor in Figure 1 and similar rings I and I2 connecting the poles at the lower end of the rotor in Figure 1. Each of the rings 6, 8, I0 and I2, as shown in Figure 5, is continuous on its inner circle but has its periphery cut back, as shown in Figure 5, to form spaces I4 between the successive magnets so that the inductive action of each magnet will be substantia-ily localized.

Each of the magnets 2 is provided between rings and B at one end and between the rings I0 and I2 at the other end with pole shoes made up of laminas I6 of the usual material used for such purposes and of the general contour and construction illustrated in Figure 6, the outer edge I8 of each of the laminae IB having a curvature corresponding substantially to the arc of a circle having a radius representing the distance of said 5 edge from the axis of rotation of the shaft 4.

In the illustrative embodiment of the invention, the magnet assembly just described is supported from the shaft 4 in the following manner: Discs 2D and 22 of some suitable non-magnetic material 10 such, for example, as aluminum or duralumin are keyed to the shaft 4 and are limited in movement along the shaft by shoulders 26 and 28 formed on the shaft 4. These discs, which are preferably polygonal in contour so that each presents a straight edge 3B for engagement by the straight edges 32 of the laminae IB of the pole shoes, have their side faces shaped to provide seats for the magnet-connecting rings 6, 8, I0 and I2. Each magnet 2 is provided in any suitable manner 20 with an upper shoulder 34 against which the ring 8 abuts and with a lower shoulder 36 against which the ring I ll abuts. Bolts 38 located between the successive magnets and extending through the ring 6, disc 2i), ring 8, ring I0, disc 22 and 25 ring I2 clamp the entire as:embly together and thus not only secure the magnes in predetermined relations to each other but also in predetermined relations to the shaft 4.

It will be understood that the invention is not restricted to the particular construction and arrangement of the holding means illustrated.

The rotor thus constructed is capable of eooperating with as many spark-producing sets of primary and secondary coils as there are in- 35 dividual magnets in the rotor and in addition each individual magnet, as it com'es into inductive relation to each set of spark coils, is adapted to produce a complete magnetic circuit whereby each coil set on each rotation of the rotor will 40 produce as many sparks as there are individual magnets on the rotor and there may be as many sparks per cylinder as there are coil sets.

It will be seen that there are many practical advantages in such a construction. For example,

.half engine speed without the need of the usual gearing required in magnetos that develop a different number of sparks per rotation from the number of cylinders of the motor with which they are to be used. Secondly, the magneto is readily adaptable to any desired multiple spark operation.

At the present time most high speed high compression internal combustion motors are red With only two sparks per cylinder and therefore in the iiiustraiive embodiment of the invention J0 only two spark coils are shown as cooperating with the rotor.

By reason of the fact that there are an odd number of magnets in the illustrated construetion and that each set of spark coils cooperates only with a single magnet at a time to produce a spark, the two sets of spark coils will not be .symmetrically arranged with respect to the rotor. In the illustrative embodiment of the invention 73 the two coil sets are shown as so arranged with respect to each other that when in inductive relation to two of the magnets of the rotor there will be three magnets between the two coil sets on one side of the magneto and four magnets between the two coil sets on the other side of the magneto. v

. The coil sets are located between and connected to the upper and lower plates and 42 of the magneto housing, these plates also carrying the upper and lower bearings 44 and 46 for the shaft 4. The two coil sets, vwhich may be designated generically as 48 and 50, each comprise a laminated core 52 to which are connected upper and lower laminated pole shoes 54 and 56 extendingat right angles to the laminated core 52 into proximity to the path of movement of the pole shoes I6 of the magnets 2. Surrounding the core 52 is a primary coil 58 and surrounding the primary coil 58 is a secondary coil 60. Each primary coil has associated therewith a condenserSZ carried by the upper plate 40 of the magneto housing.

The laminae of the cores 52 can be secured together in any suitable manner as by rivets 64, and the pole shoes 54 and 56 may be secured to the cores 52 by bolts 66 and lateral plates 68, the pole shoes 54 and 56 being also secured in defll nite relations to the pole shoes I6 of the magnets by means of bolts 10 passing through the upper and lower casing members 40 and 42 and engaging nuts 'l2 countersunk in the pole shoe laminations. To prevent turning of the bolts 10 their heads are preferably provided with holes through which a locking wire or safety pin 14 passes.l

The housing for the rotor and its associated spark coil sets comprises, in addition to the upper and lower plates 40 and 42, lateral plates 'i6 and 18 in the form of segments of a cylinder and of a substantial body, these plates being connected to the top and bottom plates 40 and 42 by screws 80.- The enclosure for the coil sets need not be so substantial as for the rotor proper. ln the illustrative embodiment of the invention the completion of the enclosure of the coil sets is effected by light U-shaped metal plates 02 and 33 clamped between the upper and lower plates e 40 and 42 and having their ends seated in groove'd edges ef the plates 1s and 1s. ,Rods s4 and s6 cooperate with the screws in effecting the clarnpingof the` plates 82 and 83 in position between the plates 4o and 42.

The housinglfor the magneto hereinabove described is preferably so mounted upon a base member 88 by which it may be attached to the motor or other structure on which it is to be mounted that by turning the entire housing with respect to the base 88 retarding or advancing' of the spark may be effected. Means now to be described are preferably provided for effecting this-relative movement of the housing and its base member 88.

The base member 88 is provided with an inwardly projecting rib 90 on which the hub 92 ofthe lower plate 42 of the magneto housing rests. A flanged clamping 'plate 94 secured to the hub 92 by screws 96 acts both to hold the bearings 4.6 in the hub 92 and to hold the housing in the base member 88, the flange of the plate 94 engaging below the rib 90.

As shown in detail in Figure 2, a spring S8 located in a recess inthe flanged plate 04 bears against one end of said recess at one end and at its other end bears against a projection' |00 extending into said recess from the base member 88. This spring 98 tends to maintain the magneto housing in its advanced spark position.

When it is desired to retard the spark the magset at diierent angles to the rotation of the shaft, by any suitable means, this partial rotation of the housing effecting a compression of the spring 98. The illustrated means for effecting such partial rotation ofthe housing to retard the spark comprises a rod |02,pivoted between ears |04 on a screw stud |06 threaded into the lower plate 42 of the magneto housing. The rod |02 may be connected to any suitable hand -lever or other device for convenient manipulationr by the operator.

vIBy reason of the fact that the main magneto shaft can be driven at half engine speed, the connection of the interrupter and distributor to the magnetois facilitated, these parts being preferably directly connected to the magneto shaft 4 for operation at the same speed. The interrupter is shown in detail in Figures 1 and 4. Mounted on the upper plate 40 of the magneto housing and surrounding the upper hub |00 of said. plate d0 and also the clamping plate i0, which holds the bearings 44 in the upper plate 40, is an insulating ring M2 and adjustably connected to this by screws H3 extending through slots therein are disc sectors H4 and H5 on which are mounted the spring contact carrying members i i6 and l l0 or" the make-and-break or interrupter mechanisrn. Screws Hl extending through slots M9 into plate '40 permit adjustment of the ring H2 `and with it bodily adjustment of the interrupter about the axis of the shaft 4. Spring members having nine faces to effect nine interrupting movements of the spring contact carriers ||6 and H8. The independent adjustment of the disc sectors permits the circuit interruption to occur at the point of maximum intensity.

The spring member ||6 carries a contact |26 that cooperates with a stationary contact |28. The spring member H8 carries a contact |30 that cooperates with a stationary 'contact |32. A5 shown in the wiring diagram, Figure 7 ofthe drawings, the contact members |26 and |30 are connected to their respective primary and secondary coils and condensers while the stationary contact members |28,'|32 are grounded.

As shown in section in Figure l, the cam |24 has on its under side a hub extension |34 which provides an extended socket for receiving the upper end vof the shaft 4, the cam hub |34 being- The distributor itself is of unique construction and is shown in detail in Figures 1 and 3. The carrier |42 for the distributor fingers is of insulating material and is enclosed in a housing |44 of' insulating material which carries the various terminals for the spark plug connections and the lead-in wires-from the high tension or secondary coils of the spark coil sets and also a lead-in from a booster for use in starting. The housing |44 with its various terminals is preferably readily 'removable and replaceable as awhole and to this end it rests 'upon'an annular flange* |46 onv the upper face of the plate 40 of the magneto housing and itself has a centering fiange |48 engaging the inner face of the nange |46. The housing |44 may besecured in position on the upper plate 40 of the magneto housing for convenient removal in any suitable manner as, for example, by screws |50.

As shown in Figures 1 and 3, -the housing |44 of the distributor has molded into its upper side two sets or rows of sockets I 52 and |54 for receiving the leads from the respective spark plugs of each cylinder, these two sets or rows of sockets being offset both axially and radially with respect to each other and the sockets of one row being staggered with respect to those of the other. The contacts |55 and |58 of the respective sets of sockets, which contacts are also molded into the housing |44, are also preferably axially and radially offset from each other and likewise staggered circumferentially.

There are, of course, as many sockets |52 as there are cylinders in the motor with-which the magneto is to be used and likewise as many sockets |54, with corresponding numbers of contacts |56 and |58.

The carrier |42 for the distributor fingers has molded into its upper face a contact ring |60 from which extends the distributor finger |62 for the upper row of contacts |56 and also has molded into its upper face a second centrally located contact piece |64 connected to the distributor finger |66 which extends down through the body of the carrier |42 into posilion to cooperate with the lower and outer row of contacts |58. Although the term contact has been used to describe the members |56 and |58, it will be understood that there is the usual small air gap between the fingers |62 and |65 and the contacts |56 and |58 of modern magneto practice.

The contacts |56 and |58 have been described as staggered circumferentially, that is, the contacts of one row being staggered with respect to those of the other row. This necessarily requires that the lingers |62 and |66 be angularly offset from each other about the distributor axis a corresponding angle of rotation.

Although this is the preferred embodiment of the invention, since it facilitates the insulation of the contacts from each other, it will be under stood that the invention is not restricted to this particular arrangement of the parts.

'Ihe contact ring |60 is engaged by a brush |68 connected to a high tension wire |10 from one of the secondary coils of the magneto and the contact piece |64 is engaged by a brush |12 connected to the high tension wire |14 from the other secondary coil. Y

In order to provide for easy starting, provision is made for connecting a booster to the distributor; for example, for connecting a hand-operated booster magneto that will furnish the sparking energy before the main magneto reaches its full effective speed. Preferably this booster connection will be so arranged that when operating it will engage with the contacts one cylinder behind the point of contact when the magneto itself is operating.

The illustrated means for connecting the booster comprises a contact ring |16 molded into' shown as engaging only one set of contacts,

namely, the inner row |56, thus causing sparking of only one spark plug to each cylinder. Suitable switches will preferably be provided for disconnecting the coils of the main magneto from the distributor when the booster is operating and for disconnecting the booster when the main magneto itself is operated.

The magneto is preferably provided with a safety gap comprising spaced points on the high tension side of the coil group for grounding the charge when it becomes too high. Inasmuch as 10 this magneto is intended primarily for use with airplanes, it is preferable. that this safety gap be so arranged as to be independent of air pressure. Preferably, therefore, the gap is provided in a vacuum tube |80 in which is located a point |82 15 connected to the ground and points |84-.and' |86 connected to the respective secondary coils of the two coil sets, the gap between the point |82 and each of the pointsl84 and.;y |86 preferably being set to ground the charge'when it reaches 18000 20 volts. A

From the foregoing description the operation of the device will be readily understood. AIn Figure 7 of the drawings the wiring diagram is illustrated and on this wiring diagram Yis shown the on and off switch |88 for the main magneto.

This application, as to common subject matter, is a continuation of my copending application Serial No. 542,586 filed June 6, 1931.

Having thus described my invention, I claim:

l. A magneto rotor comprising a rotatable bearing-engaging central supporting structure, a plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said structure, each magnet having its poles spaced lengthwise of said axis and the like poles of all of the magnets being located at the same end of the rotor, non-magnetic material connecting said magnets with said central supporting structure and magnetic material connecting the said like poles at the respective ends of said rotor.

2. A magneto rotor comprising a rotatable bearing-engaging central supporting structure, a plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said structure, each magnet having its poles spaced lengthwise of said axis and the like poles of all of the magnets being located at the same end of the rotor, a ring of magnetic material at each end of the rotor, each ring connecting all of the magnet poles at its end of the rotor, and non-magnetic material connecting said niagnets with said central supporting structure.

3. A magneto rotor comprising a plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said rotor, each magnet having its poles spaced lengthwise of said axis and the like poles of all of the magnets being located at the same end of the rotor, magnetic material connecting the said like poles at the respective ends of said rotor, journals for said rotor and non-magnetic material connecting said magnets with said journals.

4. A magneto rotor comprising a rotary shaft, a plurality of individual permanent magnets located at like radial distances from the axis of rotation of said shaft and atuniformly spaced intervals about said axis, non-magnetic supports carried by said shaft and supporting said magnets in the described relation thereto, the like poles of all of the magnets being located at the same end of the rotor, and magnetic material connecting the like poles at the respective ends of `said rotor. 75

5. In a magneto, a rotor comprising a rotatable bearing-engaging central supporting structure, a plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said structure, each magnet having its poles spaced lengthwise of said axis and the like poles of all of the magnets being located at the same end of the rotor, non-magnetic material connecting said magnets with said supporting structure, magnetic material connecting the said like poles at the respective ends of said rotor, and a stator comprising an induction coil and a laminated core having its polar ends also spaced lengthwise of the rotor axis and so located adjacent to the path of revolution of the magnets about the rotor axis that it completes a separate magnetic circuit with each individual magnet as a necting the said like poles at the respective ends/ of said rotor, non-magnetic material connecting said magnets with said supporting structure, and a stator comprising primary and secondary coils and a laminated core having its polar ends also spaced lengthwise of the rotor axis and so located adjacent to the path of revolution of the magnets about the rotor axis that it completes a separate magnetic circuit with each individual magnet as said magnets Amove in succession past said stator. Y

7. In a two-spark ignition magneto for internal combustion motors, a rotor and a separate stator :for each of the two sparks, said rotor comprising a rotatable bearing-engaging central supporting structure, individual permanent magnets equal in number to whatever number of cylinders to be red thereby are comprised in the motor with which the magneto is to be used, said magnets being uniformly spaced about the axis of rotation of said structure, arranged with their poles spaced lengthwise of said axis, and having their like poles at the same end of the rotor, magnetic material connecting the said like kpoles at the respective ends of said rotor, and

magnet as said magnets move in succession past the respective stators.

8. A squirrel-cage-like rotor for a magneto comprising a plurality of rod-like permanent magnets uniformly spaced about and substantially parallel to the axis of the rotor and arranged with their like poles at the same 'end of the rotor, rings of magnetic material connecting said magnets at their respective lpolar ends,

a bearing-engaging central structure and'nonmagnetic material connecting said magnets with said central structure. l

9. A squirrel-cage-like rotor for a magneto comprising a plurality of rod-like permanent magnets uniformly spaced about and substantially parallel to the axis of the rotor and arranged with their likepoles at the same end of the rotor, rings of magnetic' material connecting said magnets at their respective polar ends, a bearing-engaging central structure and non-magnetic material connecting said magnets with said central structure, said rings of magnetic material being recessed on theii` peripheries between successive magnets whereby each permanent magnet determines a localized field of magnetic intensity.

l0. In an ignition magneto lor internal combustion motors, a rotor comprising a rotatable bearing-engaging central supporting structure, individual permanent magnets equal in number to whatever number of cylinders to be fired therebyI are comprised in the motor Awith which the magneto is to be used, said magnets being uniformly spaced about the axis of rotation of said structure and arranged with.their poles spaced lengthwise of said axis, magnetic material connecting like poles at the respective ends of said rotor, non-magnetic material connecting .said magnets with said supporting structure, and a stator comprising primary and secondary coils and a. laminated core having its polar ends also spaced lengthwise of the rotor axis and so located adjacent to the path of revolution of the magnets about the rotor axis that it completes a separate magnetic circuit with each individual magnet as said magnets move in succession past said stator.

1l. In a magneto, an inductionvrotor element having a plurality of individual magnets, positioned about its periphery, each magnet being parallel tothe shaft of the rotor, a stator element comprising a core and pole shoes associated with said rotor element, the stator core being disposed in parallel arrangement to the shaft of the Irotor and the respective polelshoes thereof adjacent in relationship to the polar ends of the individual magnets, like poles of the magnets being magnetically connected atthe respective ends of the rotor but said magnets being ment comprising a core parallel to the magnets and pole shoes adjacent the polar ends thereofv so that, in the course of rotation of the rotor element, each individual magnet will cooperate with the core and pole shoes to complete a magnetic circuit, like poles of themagnets being magnetically connected at the respective ends of the rotor but no magnetic connection being provided between unlike poles of different magnets.

13. In a magneto, a rotor element having a vplurality of magnets spaced aboutv its periphery and situated thereon parallel to its axisvof rotation, a plurality of independent stator elements having individual cores and pole shoes situated aboutv the rotor, the cores of -each ofthe stators 70 being disposed in parallel arrangement 'to the rotor axis and the :espective pole shoes thereof 'adjacent in. relationship `tothe polar ends of the magnets, like poles oi the magnets-being magnetically connected at the respective ends of the rotor but no magnetic connection being provided between unlike poles of different magnets.

14. A magneto having a rotatable induction element formed of a plurality of individual bar magnets spaced about its periphery, and a stator element comprisinga core with pole shoes extending perpendicularly therefrom' to a position adjacent the polar ends of the magnets, so that in the`course of rotation of the induction element each individual bar magnet thereon will independently complete a field of magnetic flux in the core, like poles of the magnets being magnetically connected at the respective ends of the rotor but said magnets being otherwise magnetically unconnected.

15. A magneto having a rotatable induction element formed of a plurality of individual bar magnets spaced about its periphery, and a plurality of stator elements arranged to encircle the induction element, each stator having an individual core with pole shoes extending perpendicularly therefrom to a position adjacent the polar ends of the magnets, so that in the course of rotation of the induction element each individual bar magnet thereon will independently complete a field of magnetic flux in each of the cores, like poles of the magnets being magnetically connected at the respective ends of the rotor but said magnets being otherwise magnetically unconnected.

16. A magneto having a rotatable induction element formed of a plurality of individual bar magnets spaced about its periphery, and a stator element associated therewith positioned to facilitate the completion of a field of magnetic ux in the core thereof under the independent infiuence of each of the individual bar magnets as the induction element rotates, like poles of the magnets being magnetically connected at the respective ends of the rotor but said magnets being otherwise magnetically unconnected.

17. A magneto rotor comprising a rotatable bearing engaging central supporting structure, a

plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said structure, each magnet having its poles spaced lengthwise of said axis and the like poles of the magnets being magnetically connected at the respective ends of the rotor but said magnets being otherwise magnetically unconnected.

18. In a magneto, a rotor comprising a rotatable bearing engaging central supporting structure, a plurality of individual permanent magnets located at spaced intervals about the axis of rotation of said structure, each magnet having its poles spaced lengthwise of said axis, a stator comprising an induction coil and a laminated core having its polar ends also spaced lengthwise of the rotor axis and so located adjacent to the path of revolution of the magnets about the rotor axis that it completes a separate magnetic eircuit with each individual magnet as said magnets move vin succession past said stator, like poles of the magnets being magnetically connected at the respective ends of the rotor but no magnetic connection being made between unlike poles of different magnets.

MALCOLM E. SPGHN.

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