US2537856A

US2537856A - Magneto

Info

Publication number: US2537856A
Application number: US689876A
Authority: US
Inventors: Walter J Raleigh
Original assignee: SCOTT ATWATER Manufacturing Co
Current assignee: SCOTT ATWATER Manufacturing Co; SCOTT-ATWATER MANUFACTURING Co
Priority date: 1946-08-12
Filing date: 1946-08-12
Publication date: 1951-01-09
Anticipated expiration: 1968-01-09

Description

Jan. 9, 1951 w, 1 RALEIGH 2,537,856

MAGNETO A Filed Aug. 12, 1946 4 Sheets-Shea?I l FL ciu-1 l 2 20 A 'TZ 37 60d 6360 62 5 5A- 4 33'" 'Q' sea sam Y 37 56 50e. 4S e4 57 E Y 4s 6o e 43 sa /2 gg se, 4. 32 57a a O L\v3 o j.. IL. 27 3 I I t /l' ,-26 l 3 o 33 f V 26a (Q.) IJ -,:J O Z4 6G 43 2Gb 20C c zelo F1' .-2 szd Cj '4 Inventar sab ALTER .RALEnCfH' zzb 2z ze, 20h. Attor 4 Sheets-Sheet 2 lnvenbor-z WALTER J. RA L'Enq-H MAGNETO W. J. RALEIGH `Ian. 9, 1951 Filed Aug. 12, 1946 Figf 20h zo Jan. 9, 1951 w. J. RALEIGH 2,537,856

y MAGNETO Filed Aug.. l2, 1946 4 Sheets-Sheet 3 Fig-5 206 "12. God 6D 2Gb Goe' Gob gz 7 zee 4S 24' ifs: 62 38 ,l/ 26o 33 32a 3o a l/1/ 27 51a f GG 3o 6o zob ev ze@ sa 66 64 67 lfm/enfor- WA LTER JRALE cfH W. J. RALEIGH Jan. 9, 1951 lMAGNETO 4 Sheets-Sheet 4 Filed Aug. 12, 1946 nvenor v WA LTER J. RnLEcrn A't'tor-nag.

Patented Jan. 9, 1951 MAGNETO Walter J. Raleigh, `Mnneapolis, Minn., yassigner to Scott-Atwater Manufacturing Company, Minneapolis, Minn.,.a corporation ofMinnesota Application August I2, 1946,` Serial No. 68,9&7 6A

19 Claims.

1 'This invention relates to a magneto. Such magnetos are used in connection with internal combustionv engines used in outboard motors and other devices.

Itv is an, object of this invention to prov-ide a magneto having high eiciency, one which requires a small amount of magnet metal and one whichis compact and convenientV to manufacture.

It is afurther object of the invention to provide a magneto comprising a coil having primary and secondary windings, a core extending axially through said coil, a rotatable member having an inner portion movable in close proximity to the inner end of said core and separated therefrom by an air gap and having an outer portion carrying a magnet movable in close proximity to the outer end of said core and separated therefrom by an air gap, whereby any lateral movement of said rotatable member will not increase the total dimension of said air gaps.

It is another object of the invention to provide a magneto comprising a stationary member, a coil having primary and secondary windings mounted on said member, a core member preferably of laminated structure extending axially through said core, together with compact, novel and-*efficient means for securing said core member to said iirst mentioned member.

It is also an object of this invention to provide a magneto comprising a stationary member, a coi1 having primary and secondary windings mounted on said member, a core extending axially through said coil, a rotatable member having portions movable past the ends of said core respectively, a magnet carried in said rotatable member and movable past the outer end of said core, and an auxiliary magnet pole carried by said rotatable member and spaced circumferentially from said magnet carried by said rotatable member, said core having an auxiliary arm spaced circumferentially from the outer end of said coil, whereby said magnet pole acts to reverse the flow of magnetic flux through said core.

It is still further an object of the invention to provide a magneto having a coil, together with a novel core frame, and means for securing the same in position.

It is also an object of this invention to provide a novel magnet structure and method o'f making the same, together with a novel structure of contact-carrying members. "'fffThese and other objects and advantagesof the invention will be fully set forth in the following description made in connection with the Vaccompanying drawings in Which likereference charac-v ters refer to similar parts throughout the several views and in which:

Fig. -1 is a view partly in plan and partly in horizontal section taken on line I l of Fig. 4, as indicated bythe arrows;

Fig. 2 is a partial vertical section taken substantially on line 2 2 of Fig. 1, as indicated by the arrow and shown on an enlarged scale;

Fig. 3 is a vertical section taken on line 3 3 of Fig. 1, as indicated by the arrows;

Fig. 4 is a vertical section taken on line 4 of Fig. l, as indicatedbythev arrows;

Fig. 5 is a View similar to Fig. 1 showing a d-uplex magneto; y

Fig. 6 is a partial horizontal section taken on line 6 6 of Fig. 7;

Fig. 7 is a partial vertical section taken on line 3 3 ofFig. 1;

Fig. Sis a partial vertical section taken on line 8 8 of Fig. 5, as indicated by the arrows;

Fig. 9- is a partialvertical section taken on line 9 9 of Fig. 5, as indicated by the arrows;

Fig. 10 is a wiring diagram for the device;

Fig. 11 is a plan view of a` rotatable support used with other parts, indicated in dotted lines;

Fig. '12 is a partial vertical section taken on line I2` I2 of Fig. l;

Fig. 13 is a plan View of' a rotatable core frame used with attached parts; and

Fig. 14 is a horizontal section taken online M m errug. 2.

Referring to the drawings, a magneto structure is showncomprisng a plateV or support 2D; Member 20v has a hub 20a which is` split diametrically and is clamped* by a. pair 0f clamping bolts 2i at opposite sides thereof to a trunnion 22a forming part of a `member 22 forming part of the engine structurewith which the magneto is used. Member Z2 has a collar 22h on which hub 2cd rests. Plate 2,91 hasan annular rim, 20o and openings 211e therethrough atv opposite sides thereof so that it is` somewhat in the form of a spider. Platelll; caribe; oscillated about trunnion 22a, for thepurposeiof changing the time at which the spark will occur inthe spark-plug inthe engine in relation to, the engine shaft. Otherwise plate. 2l)4 is stationary-.and forms a support for the stationaryparts of the` magneto.. A coil 24 .is provided, the same having theusual vprimary winding 24a thereon and a. secondary wind Iing 24h having a much larger number of turns than the primary winding. A core 26 is prov ided having one portion or leg 26a which extends axially through coil 24- and supports said 3 coil. Core 26 is shaped in plan, as shown in Figs. 1 and 5, and it will be seen that the same has an auxiliary portion or leg 26h which extends at an angle to portion 25a and has a free terminal portion spaced from the free terminal end of portion 26a. Core 26 is preferably made of laminated structure and thus comprises quite a large number of superposed thin plates, as shown in Figs. 3 and 12, and an insulating cement may be placed between said plates. The plates will be pressed tightly together so that the core forms a unit. The portion 23a projects somewhat at the outer end of coil 24 and a yoke member 21 of general U-shape has its bight portion extending over the top of portion 25a and its side portions extending through openings in plate 20 and equipped with suitable nuts 28 at the underside of said plate. Said portion 26a is thus very firmly supported on plate 2i! and securely drawn into position and held by yoke 21. Some of the laminations or thin plates comprising member 26 which are adjacent plate 20 are extended to .form lugs 26e and these are provided with openings or slots 25d through which extend a clamping screw or bolt 29. Said laminations adjacent plate 2@ are also extended from portion 26 to form lugs 25e which are apertured to re ceive a securing screw or bolt 39, which, like bolt 29, will be threaded into plate 25. Said laminations adjacent plate 23 are cut back to fit against hub 25a. |These act to accurately locate the core in a position concentric with shaft 33. Core 25 is thus very firmly supported by and secured to plate 20. A rotatable member 32 is provided having a hub 32a secured to a tapered portion of the engine shaft 33. Shaft 33 has a reduced threaded portion at its upper end on which is threaded a nut 34 engaging a Washer 35 disposed on top of hub 32a. Shaft 33 extends through a bearing or bushing 36 in trunnion'22a.. While rotatable member 32 could be made in various ways, in practice one eicient method of making this member has been to provide a portion comprising a hub 32a and a portion 32h extending radially therefrom having outer circumferentially spaced

end portions

32e and 32d. Spaced headed screws 31 extend vertically through portion 32d from the top thereof and are threaded into a member 38 which extends downwardly from portion 32d and is of the same width as said portion, said member 38 having a recess in its inner side in which is disposed a member 39 forming a pole shoe comprising a multiplicity of thin superposed plates of metal, such as iron. The surfaces on which the heads of screws 31 rest are disposed some distance from the top of member 32 thus forming a portion 32e. Said member 39 is of somewhat greater width than member 33. Member 39 embraces the lower portion of member 38 extending about three sides thereof and overlapping member 38 somewhat at the fourth side. Member 39 seats against a shoulder 38a at its upper end and member 38 is provided with another shoulder 38b at its outer or opposite side. lMember 38 constitutes an auxiliary magnet pole. Portion 32o has a reduced outer end portion 32'f and a member 4l] is disposed below and in engagement with portion 32e and having the same Width as portion 32e. Another member 4I is disposed immediately below and in engagement with a magnet 4U, the same having the same Width as magnet 49 and also having a depending portion `Het of reduced width thus forming lateral shoulders 4Ib. Clamping plates 43 extend along the sides of members 32o, 40 and 4l, having their upper ends bent over shoulders ad jacent the top of members 32e and their lower ends bent under the shoulders Mb. Plates 43 thus form yokes

whichsecure members

32e, 40 and 4| together. The lower reduced portion 41a has a member 44 extending across its inner side and across its ends and slightly overlapping its outer side, which member 44 is made of a multiplicity of superposed plates made of metal, such as iron. Portion lla constitutes a magnet pole shoe.

With hub 32a and member 32h with its attached parts so constructed, the same is placed in a mold and the remaining part of member 32 formed by pouring metal around the same so that this body of metal completely surrounds portion 32h and portions 32o and 32d. The inner side of

members

39 and 44 comprising the superposed plates are exposed at the inner side of the annular portion of member 32. As shown in Figs. 3 and 4, it will be seen that this annular portion 32h depends from a top circular portion 321'. Member 32 revolves with shaft 33 to which it is secured. As shown in Fig. 1, it will be seen that the inner surface of member 44 is concave and parallel to the outer convex end surface of arm 26a forming the core of coil 2'4. Said surfaces are separated a short distance by an air space, commonly `called an air gap. It will be also seen that the inner end of member 26 is concave in shape and parallel to the outer convex surface of hub 32a, said latter surfaces being separated a short distance by an air space, commonly called an air gap. Said surfaces at the inner and outer ends of member 26, said outer convex surface of hub 32a and the inner surface of member 44, are all concentric with the center of shaft 33. It will also be seen from Fig. l. that the inner concave surface of member 39 is in the same cylinder as the inner surfaceV of member 44 and will thus move in close proximity to the outer end of core 26a. Magnet member 43 supplies the magnetic ilux for producing the desired current and spark and the magnetk pole 38 forms a reversing or auxiliary magnetic pole.

In the operation of the device the circuit of the primary winding on. coil 24 is successively broken. Conductor 41 forms one end of this Winding and this is secured to a clip 4B secured to member 20 by a screw 49. This conductor is therefore grounded on the frame of the engine. Another conductor 53 forms the other end of the primary Winding and this is secured to a clip 52 which is retained on a condenser 12 by a screw 53 and nut 54. Said condenser is sup-ported from lug Zilg by screw 23h. From clip 52 a conductor 55 extends to and is connected to a contact member 55 having a portion 56a extending through one end of a lever 51 which is made of insulating material, such as hard iiber, and which is oscillatable on a pin 58 secured in and upstanding from member 29. A member 50 is also secured to member 2G, the same being of plate-like form and having a portion 60a which is bored to receive pin 58, the same being disposed on and in contact with member 2B and separated from lever 51 by a washer or collar 6l. Member 63 is also provided with an elongated slot 39h through which passes a headed screw 62 which is threaded into member 20 and holds member 69 in iixed position. Member 60 is provided withV a .contact member 63 adapted to be engaged by- Contact member 56 and the portion 56a thereof. Mein"-e autres@ herthas a lug projecting at one vside inV which. is formed aslot or recess 6M'. Below Lslot 60d is a notch or recess 26e. Member 60 also has a portion tile upstanding at one sideY thereof adjacent contact member 53, which portion tile has a small slot 66j extending laterally thereinto adjacent the top thereof. Lever 5f? at the end thereof opposite contact member 5t is provided with a, projecting portion or lug Sla adapted to be engaged by hub 32a which forms a cam and is attened at one side, as shown at 3'27, at' which point it does notengage lever 5I. Lever 5T is held in position with contact members 5t' and 63 in` engagement by a torsion and compression coiled spring 613i having one end' bent to extend; vertically into a hole in lever and having' its' other end extending laterally and 'pressed-down- Wardly to be disposed in slot te?. Spring Gexerts both torsion and downward pressure on lever 51. v Hub 32d may be provided with a 'peripheral recess 321C at one portion which is circumferentially spaced from portion 32g. @ne end of the secondary winding on coil Ell' will be grounded on the frame of the device and the other end of said secondary winding is connected; to. a conductor @t preferably enclosed in a cable or tube 6l which extends downwardly through plate. or member 2li and will be providedwith a suitable connection not shown by which Ait can be connected to the spark plug on the motor or engine. It may be stated that member 2d can have a bracket 5,3 attached thereto having secured thereto ay handle SS by means of which member 2e can be oscillated on trunnion 22 to vary the position of the spark. As shown in Fig. l, member 2t is `constructed to carry two coils and the necessary parts therefor when a two cylinder engine is used. The annular rim of member 32 may be provided with circumferentially spaced openings 32m for reducing weight, as shown in Fig. l.

A wiring diagram for the magneto is shown in Fig. '10. Coil 2d is shown, one end of the primary winding 2/ia as well as one end of the secondary winding 25th thereof being connected to ground lli, which, as previously stated, will be the frame of the device or engine. Magnet pole di is shown as is the reversing pole 38. One end of the primary Winding 2da is connected by the conductor 50 to the contact member 56, which contact member is adapted to engage contact member S3 which will be connected to a ground l l. Preferably a condenser l2 is connected across the

contacts

56 and 63 by a conductor T3. Lever 5l" is shown with its end engaging a cam hub 32a. A spark plug l@ is shown which will be disposed in the engine cylinder as usual. One terminal of the plug will as usual be connected to a ground 'l5 and the other terminal of the plug is connected to the secondary winding of coil 24 by the conductor 5E. Y

In the operation of the device, shaft 33 will be rotated and member 32 will rotate with shaft 33. Magnet poles 33 and il will thus be carried past coil 24' and its core 25. When the main magnet pole 4I is directly radially opposite core leg 26a, the flux will pass through the iron member 44, thence across the air gap at the outer end of core leg 26a, inward to hub 32o, upward in hub 32 and out through the portion 322; o member 32 and downward through portion 32h to the. mag'- net. The now of flux is at a maximum at said position. As magnet pole 33 approaches core Aleg 260: and magnet d@ comes opposite core leg 2Gb, 'the flow of iux will reverse as the flux of ux takes place.

will now lpass into leg 26o and will pass. out` wardly through leg 26a. 'I-oV produce this reversing of the flux path, the auxiliary magnet pole 38 is used'. This will be polarized opposi'tely' to magnet pole dl. The flux will now ow outwardly through core leg a returning tomagnetill through pole- 33 and portion 32d. The reversed ow of ux will not be as intense as the initial flow inwardly through leg 26a due to: the fact that a considerable part of the reversel ow will follow a parallel path through hub 32a. To reduce the flow of'lux through this parallel path, the recess 32k is formed in hub 32a, which recess will bey opposite core frame 2S when the reversal The current generated in primary winding 24a, the circuit of which will be closed through

contacts

56 and 63, will be greatest when the change in the iiowv of flu-X is greatest. This point approximately is reachedl when the magnet poles li and 3S occupy the position shown in Fig. 5 relatively to core leg 26a.

v At this time the cam on hub 32a moves lever 5"? and the

contacts

56 and 33 are separated, thus breaking the circuit through the primary 'winding 24a. This breaking of the primary circuit induces quite a high voltage in the secondary winding 25o in the usual manner and a spark is caused to jump across the electrodes oi spark plug 14.

In Fig. 5 the arrangement for a duplex magneto or one for use in a two cylinder engine is shown. The structure is the saine except thatV an additional coil 24 is shown located diametrically opposite the described core 2d, and a second core frame 2t is used which is disposed oppositely and reversely to the core frame 26, shown in Fig. l. The other auxiliary parts are merely duplicated anu. are designated by the same num? bers as used in Fig. l. Hub 32a will have the said cam portion 327' thereon. In operation of the magneto shown in Fig. 5, the magnet pole 4l will create a iow 0f flux through both core frames 26 successively as it rotates successively past the same. The reversing magnetic pole 38 will likewise reverse the ux in both core assemblies 26 in the manner above described. The circuits of the primary windings will be opened at the proper time by the successive action of levers 51 so that the secondary winding of the coil will produce the spark in the spark plugs. As shown in Fig. 5, there will be two of the cables or tubes 6l which will extend downwardly through the holes 2W in member 25B.

From the above description it will be seen that I have provided a simple, a compact and highly elicient structure of magneto. The magnet used is made of a high energy magnet metal. It is only necessary thus to use a small length or body of this magnet material. As shown in Figs.' `2 and 3, the magnet is in the for-m of a simple block with parallel sides which can be inexpen# 'sively finished by grinding. The magnet is effectively and eiciently clamped in the-laminated structure shown and described. The member 32 forms a fly-wheel of the engine and the magnet is so mounted that centrifugal force due to the rotation of said fly-wheel does not act to separate its working faces from the adjacent iron parts. In the present structure the magnetic circuit is about as short as it is physically possible to construct by encircling the transformer coil winding. The radial portions 32h could be made to follow closely the outer surface ofthe coil 'pro- Viding a path of minimum length. In practice it has been considered preferable to makethe path somewhat longer so as to provide a clearance around the coil to reduce electrical stresses on the coil insulation. Other types f magnetos have had magnetic parts which were quite short although not as short as the path in the present structure, but such types imposed physical limitations on the amount of magnet metal which could be used in a given size of the device. In the present structure high energy magnet metal could be used throughout portion 32h. Another advantage of the present structure is that the air gaps are at the outer and inner ends of the coil core. This results in the advantage that the sum of the length of these gaps is always the same regardless of any lateral motion which might occur in the shaft or fly-wheel. Should the shaft run out of true somewhat, this will not increase the sum of the air gaps. The length of one air gap would be increased and the length of the other decreased. A very small variation in the length of the air gap will cause a marked decrease in voltage output. Even an increase ol' a thousandth of an inch in the total lengths of the air gaps will cause a marked decrease in voltage. In the present structure this decrease of voltage is eliminated. An unchanging magnetic reluctance and constant voltage output throughout the life of the engine is thus obtained. The reversal of the flux by the provision of the reversing magnet or pole piece and auxiliary core leg gives a high efficiency. The core frame is lmade of laminated stock to avoid parasitic eddy currents which tend to be generated crosswise of the magnetic field and to circulate within the body or the core. Such eddy currents are largely prevented by the laminated structure. Another advantage is obtained by not connecting the laminations or plates of the core frame with rivets. The individual plates or lamina/tions are iastened together with insulating cement. A metalbonding, thermo-setting cement is used having great strength and this is applied to the iron stock from which the laminations are cut. When the plates are stacked to form the core frame, pressure is applied to the assembly and the whole assembly is then placed in an oven where it is brought to the correct final curing temperature. This produces a strong rigid assembly with good electrical insulation between adjacent laminations which entirely eliminates all inter-lamination current and eddy current losses. To insure correct alignment ci the communicating surfaces of the core frame and rotating member 32, said core frame-is located by a turned boss on the member 2li which is concentric with the rotating member or fly-wheel shaft 33. The lower lamination on the core frame has a concentric surface which is forced radially against said boss while the securing screws 29 and 3) are tightened. This method of locating the core frame produces accurate alignment of the air gaps without the necessity of assembly doweling and detrimental machining of the lamination faces which has been the practice heretofore. The structure for holding the core frame in piace is quite eflicient and the yoke 21 insures that the laminations will be held tightly in contact and that no looseness will result in operation. The laminated members embracing the magnet poles are formed by a unique method. As shown in Fig. 5, members 3d and 44 extend about three sides of the magnet poles.

Members

39 and 44 have lugs at their open sides which initially project outwardly. The inner side of the recess formed in

members

39 and 44 is initially made with a slight convexity. The magnet poles are placed within said members and the lugs at the ends of the opposite sides are then pressed inwardly to embrace the magnets and extend partly over the fourth side thereof. Pressure is applied which is suiiicient to cause the surface at the inner side of the recess to become rectilinear and engage a surface of the magnet pole throughout its entire extent. The

members

39 and 44 are thus upset and pressed into close engagement with the magnet poles and stress is set up in the metal thereof which acts to permanently lock the laminations together and eliminate any air gaps.

It will be seen that two clamping screws are used to clamp member 20 about the trunnion 22. This is an advantage over the common practice of using only one screw at one side of the hub. Where a single clamping screw is used, the trunnion is caused to wear unevenly causing the stationary parts to be misaligned, thus changing the magnetic gaps and adversely affecting magneto performance. These objections are obviated in the present structure by splitting the hub of member 2i) axially and providing the two symmetrically arranged screws 2l. The clamping force is then applied over the whole interior of the split hub and wear occurs more slowly and is evenly distributed on the trunnion, thus preventing errors in the positioning of the parts. A smaller clamping force is thus required and less frequent adjustment is necessary. The mechanism for breaking the primary circuit is very compact and efficiently mounted. As above set forth, spring 64 exerts both downward pressure and 'torsional stress on lever 51. The parts can be assembled, as shown in Fig. 14, and when spring til is placed in position and its upper end depressed and sprung into the slot 601, lever 51 is then held securely in position. Provision is made for easily adjusting member 60 to regulate the position of contact member 63. Screw 62 will be loosened and the operator can then take an implement such as a screw-driver 16, shown in Fig. 8, and position the same in slot 65d with the end of the implement seating in recess 20e. Implement 16 can now be moved about its end in recess 29e and member 60 will be oscillated about pin 58. A very iine adjustment can thus easily be made and screw 62 will then be tightened to hold member 60 in place. The member 60 can thus easily be moved to cause a change of a few thousandths of an inch in the contact adjustment.

The device has been amply demonstrated in actual practice, found to be successful and efcient and is being commercially made.

It will of course be understood that various changes may be made in the form, details, arrangement and proportions of the device and in the steps and sequence of steps of the method without departing from the scope of applicants invention, which, generally stated, consists in a method and device capable of carrying out the objects above set forth, such as disclosed and defined in the appended claims.

What is claimed is:

l. A magneto having in combination, a stationary member, a coil having primary and secondary windings supported on said member, a core extending axially through said coil, a rotatable member having an outer portion movable about said coil, a magnet structure carried by said outer portion and movable in close proximity to the outer part of said core and spaced therefrom by an air gap, said rotatable i9 :member having ian inner central portion rotating therewith .forming `par-t oi the .magnetic circuit and moving in close proximity to the-.inner part yof saidcore and separated therefrom by Yan .air

gap, whereby any lateral .movement of said. .ro

.tatable member or central. portion. will. not .increase the sum of the dimensions. of said. air

.gaps

lThe. structure set .forth in. claim 1., said .core extending radial-1y oi said rotatable member and having Ia concave Surface adjacent said central portion and a convex surface adjacent said. magnet structure, said magnet structure having -a concave surface .parallel to said convexsurlface ofsaidcore.V l l 3.. A magneto having in combination, a stantionary member, a coil having primary and secondary windings supported on said member, a .coreI extending axially through. said. coil, va shaft, ajrotatable member havingja hubv secured to said 'shaftjand having an outer annular portion movablef about said coil, a magnet 'structure carried by said rotating 'member and movable in vclose Proximityto the. outer end orga-1d lcore and 'spaced therefrom by an air gap, said hubiorming ,part of the magnetic circuit and moving in close proximity to the inner end of said core and separated there-from -by an `air gap, whereby any/lateral movement of said shaft or rotatable '-membei' 'will not increase the sum of the distances across said air gaps.

4. A magneto .having in combination, a stationary member, a coil having primary and secondary windings supported on, said member, an iron core .extending 'axially through said coil, a

. shaft, a iiywheel having a cylindrical hub seiui'eilA to "said" sh'a'ft 'and having 'an outer portion rotatable l'about said -coil, spaced magnet pole shoes carried by said outer portion and movableiny close proximity tosaid core., Said hub forming part 'of the magnetic circuit and movable in close proximity to the inner end of said coil, said hub having a flat portion forming a `ca'm,*contacts yconnected 'respectively to the ends ci; said primary winding and adapted to be opened-by -acti-0110i said cam.

`5. A magneto having int'c'onbination, a sta- Y tionary member, a 4coil havingprimary and secfondary 'windings carried by said member,4 a frame having a portion forming a core for said coil and extending axially therethrough, said frame being made 'of `a, multiplicity of jsuperposed thin plates, a yoke extending over said frame at one .end foi said coil and` secured to said member holding 'said plates tbg'thei, 'certain of said 10 having lugs projecting at said. side at each end of said recess, a piece of magnetically conducting me-tal fitting in said recess and having a side at the open side of Asaid recess, said lugs .being bent over said side of said piece said side being eX- posed between. said lugs.

8. The method of vfor-ming a magnet pole assembly which consists 4in forming a member of a multiplicity of thin superposed plates, then forming a recess in one side of said member and Vforming lugs -on said member projecting at either end oi` said recess, said recess being substantially rectangular .in plan .and having an inner side with aslightly convex surface, forming a piece of magnetic material substantially fitting in said recess but having .a .plane side adjacent `said convex surface, placing said piece .in said recess with ysaid plane side adjacent said side of .said

. additional. .steps of placing an insulating cement between said plates and then heating said assembly.

.10.. A .magneto .having in combination, a -station-ary member, a coil mounted on .said member hav-ing primary and secondary windings, a core extending axially through said coil, -a vrotatable member having an annular portion movable about said coil., said portion having a recess `at its .inner side., a laminated member disposed in said recess, said laminated imem-ber having a recess therein, a piece of magnetic metal disposed in said recess and `engaged' on three sides thereby, said laminated member having por-tions extending overthe fourth side of said piece, `said laminated member having a concave surface movable in close proximity to 'one end of said l rotatable member having a central hub and an plates adjacent said member having projecting portions forming flat lugs, means extending through said lugs and secured to said member for holding said frame in place, and a rotating member movable adjacent said coil and frame, and a magnet carried by said rotating member.

6. A magnet pole assembly for a magneto comprising a member formed of a multiplicity of superposed thin plates, said member having a recess at one side thereof with portions projecting at each end of said recess, and a block forming a magnet pole disposed in said recess and substantially fitting therein, said portions extending over one side of said block and holding the same in said recess said last mentioned side being exposed between said portions.

7. A magnet pole assembly comprising a member formed of a multiplicity of thin superposed plates, said member having a recess at one side substantially .rectangular in plan, said member `outer portion movable past lsaid coil, said hub Ifor-ming part of the magnetic circuit, a core member having a leg extending axially through n said coi-l' 'and substantially radially Aof said rotatable member, said core member having an auxiliary leg extending outwardly at an angle to said leg, the outer ends of said legs thus being spaced circumferentiallv of said rotatable member, said core member havingan inner portion adjacent said-hub. a magnet pole shoe carried in said rotatk able member so as to move past the outer ends of said legs, a reversing magnet pole shoe carried in said rotatable member spaced circumferentially from said rst mentioned shoe. said hub having a portion of reduced diameter adapted to be opposite said inner portion when said reversing shoe is opposite said first mentioned leg whereby the magnetic flux is caused to move radially outwardly in said core and not through said hub thus causing a reversal of flux travel.

13. A magneto having in combination, a stationary member, a coil having primary and secondary windings carried by said member, a frame lhaving a portion forming a core for said coil and extending axially therethrough, said frame being made of a multiplicity of superposed thin plates, a rotatable member, a magnet assembly carried by said rotatable member and movable about said coil and frame, a shaft on which said rotatable member is mounted, a bearing for said shaft having a hub with a surface concentric with said shaft, certain of said plates having concave recesses therein fitting against said hub to locate said frame.

14. A magneto having in combination, a stationary member, a coil having primary and secondary windings mounted on said member, a rotatable member, a shaft on which said rotatable member is mounted, a third member having a hub with a surface concentric with said shaft, a core member for said coil, said core member having a portion fitting against said surface, and spaced means securing said core to said stationary member.

15. A magnet assembly for a magneto comprising a magnet pole shoe formed of a number of thin superposed plates, said shoe having a recess at one side thereof, and a magnet pole piece disposed in said recess and held therein by prtions of said shoe at the sides of said recess extending thereover.

16. A magneto having in combination, a stationary member, a pair of coils carried by said member each having primary and secondary windings thereon, cores in said coils respectively, a rotatable member having an inner central portion movable adjacent the inner ends of said cores respectively and an outer portion having a substantially cylindrical surface movable past the outer ends of said cores respectively, said coils being disposed in reverse relation at opposite sides of the axis of said rotatable member, magnet assemblies carried. by said rotatable member and spaced less than 90 degrees apart, each comprising magnet pole shoes having concave surfaces movable close to the outer ends of said cores, and

reverse relation at opposite sides of the axisof said shaft, magnet assemblies carried by said rotatable member comprising magnet pole shoes movable in close proximity to the outer ends of said cores, and means for breaking the circuits of said primary windings of said coils in each revolution of said shaft.

18. In a device of the class described, a stationary member, a coil having primary and secondary windings carried by said member, a'core member made of a multiplicity ofrthin superposed plates, said core member having a portion extending axially through said coil and projecting at the outer end thereof, an integral U -shaped yoke extending over and embracing said portion and binding said plates together, and means securing the bottom of said yoke to said stationary member.

19. The structure set forth in claim 18, said portion engaging said stationary member, said yoke having threaded lower ends extending through a portion of said stationary member, and nuts secured on said ends whereby said plates are clamped between said yoke and stationary member.

WALTER J. RALEIGH.

REFERENCES vCITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Date Number Name r, Re. 14.113 Thordarson Apr` 18, 1916 3 874,506 Higgin Dec. 24, 1907 1,429.601 Luzy Sept. 19, 1922 1,511.345 Kaisling Oct. 14, 1924 1,799,790 Helgason Apr. '1, 1931 D 1,893,840 Martin Jan. 10, 1.933 1,916,700 Walther July 4, 1933 1,924,311 Frey Aug. 29, 1933 1,933,040 Reis I Dec. 5, 1933 2,081.800 Dunham May 25, 1937 2,101,392 Harmon ---e Dec. 7, 1937 2,191.087 Spengler Feb.2o,194o 2,192,985 Reis II Mar. 12, 1940 2,349 620 Hansen May 23, 1944 2,392,500 Phelon Jan. 8, 1946 2,394,724 Snorek. Feb. 15, 1946 5 2,447,366 Ruseite Aug. 17, 194s FOREIGN PATENTS I Number Country Date 396,017 Great Britain Oct. 19, 1931