US2446446A - Breakerless magneto - Google Patents

Description

Aug. 3, 1948. E. F. WARGIN ETAL BREAKERLES S MAGNETO Filed April 29, 1947 Fig. I.

MAGNET Inventors Joseph R. Harkness,

., v .m z m FM W o m w A, P La W h d T E y b Patented Aug. 3, 1948 BREAKERLESS MAGNETO 7 Edward F. Wargln, San Anselmo, Calii'., and

Joseph R. Harlmess, Schenectady, N. Y., asslgnors to General Electric Company, a cor- --poration oi New York Application April 29, 1947, Serial No. 744,688

The present invention relates to magnetos and more particularly to magnetos or the breakerless WW- It has long been realized that the elimination of the breaker mechanism in a conventional ma neto would be desirable in the interest of simplifying the mechanism and eliminating maintenance troubles. Heretolore, breakerless magneto ignition systems have not been able to compete with conventional magneto systems on the basis of size and weight. Favorable comparison has now been made possible by the development of a novel ignition system which stores consecutive magneto impulses and by improvements in the design of the magneto generator. The ignition system is disclosed and claimed in a copending application of Edward F. Wargin, Joseph R. Harkness, and Donald C. Peroutky, Serial No. 731,230, filed February 27, l97, which is assigned to the same assignee as the present invention. The present invention relates to the construction ofthe brealrerless magneto per se and has for its general object the provision of an improved device of this character.

A more specific object of the invention isto provide a breakerless magneto which is compact in design and which has relatively high impulse energy and output voltage as compared with previous designs.

For a better understanding of the invention reference should be made to the following specificatlon taken in connection with the accompanying drawing in which:

Fig. 1 shows a breakerless magneto having improved constructional details forming the subject matter of the present invention, and

Fig. 2 is the same as Fig. 1 except that the rotor is rotated counterclockwise an angular amount equal to the width of a stator tooth.

Referring to the drawing, there is shown a breakerless magneto which is well adapted for use in a breakerless magneto system of the type disclosed in the above mentioned copending application. It is to be understood, however, that its use is not limited to this system and that it may be used to supply power to other types of ignition systems. The magneto generator i is of the so-called inductor type and comprises s. rotary member 2 mounted on a drive shaft 3. The rotor 2 is formed of magnetic material and is preferably of laminated construction, the rotor being provided with a plurality of circumferentially-spaced, salient teeth 4. Extending around the rotor member 2 is a stator member comprising four, spaced, arcuate pole pieces 5, 6, l and 8 5-Claims. (Cl. 171-209) which are formed 01' magnetic material and which are preferably of laminated construction. Each stator pole piece is provided with a plurality of inwardly extending projections or teeth 9 which cooperate with the rotor teeth t in establishin different low-reluctance magnetic circuit paths through the rotor and the stator pole pieces as will be subsequently i'urther described.

The magneto i is provided with two output coils it and it which are carried, respectively. on the magnetic core members it and it. As illustrated in the drawing, the core member i2 is arranged magnetically to interconnect the stator pole pieces 5 and 8 While the core member i8 isarranged magnetically to interconnect the stator pole pieces l and t, the core members it and it being located on diametrically opposite sides of the magneto stator.

For the purpose of providing a source of magnetic flux which is periodically directed through the core members 82 and iii in opposite directions upon rotation of the rotor member 2, there are provided two permanent magnets iii and iti1ocated on diametrically opposite sides of the stator. As shown, the permanent magnet it is arranged so that its polar extremities abut the adjacent ends of the stator pole pieces 5 and 8 and thereby forms a magnetic link between the two polo pieces. Also, as shown the permanent magnet i5 is similarly arranged with its polar extremities abutting the adjacent ends of the stator pole pieces 6 and i. This magnet also acts as a magnetic link interconnecting these two pole pieces.

When the rotor 2 of the magneto generator rotates the magnetic flux of the permanent magnets i4 and i5 is caused first to pass through the core members l2 and H3 in one direction and then to be rapidly changed or switched so as to fiow through the core members in the reverse direction, this alternate and rapid flux switching causing high induced voltages in the magneto output coils Ill and M. This flux switching action of the magneto generator may more easily be understood by a consideration of the low-reluctance magnetic fiux paths when the generator rotor is in each of two diiferent positions indicated respectivcly in Figs. 1 and 2 oi the drawing. When the rotor 2 is in the position indicated in Fig. l of the drawing, the rotor teeth 4 lie opposite the stator'teeth of pole pieces Band 8 so that a low reluctance path is established. interconnecting these two pole pieces diametrically across the rotor. At this time the rotor teeth and the inwardly extending teeth of pole pieces -5 and l are out of registration so that the flux path between these two pole pieces entendmg diametrically across the rotor is of relatively high reluctance.

4 metrically across rotor member it, stator pole piece it, core member l3, and stator pole piece l and back to the south pole of permanent magnet When the rotor member 2 of the magneto generator rotates counterclockwise an angular amount equal to the width of a stator tooth from the position shown in Fig. i, it occupies the position shown in Fig. 2. Referring to Fig. it will be noted that the rotor member 2 now establishes a low reluctance magnetic circuit path extending diametrically across rotor f2 between the pole pieces 5 and 5. At this time the rotor teeth Ll, lying opposite the stator pole pieces 5 and 8, are out of registration with the stator teeth 9 so that the reluctance of the magnetic circuit path extending diametrically across the rotor between the stator pole pieces 6 and ii is relatively high. With the magneto rotor in the position shown in Fig. 2, it will be noted that there are now two low reluctance magnetic paths whereby the magnetic flux of the permanent magnets i i and it threads the core members l2 and iii in the opposite direction from that shown in Fig, 1. One

of these magnetic circuit paths may be traced as follows: the north pole of permanent magnet i l, stator pole piece ti, diametrically across rotor member 2, stator pole piece 7, core member l3, and stator pole piece 3 back to the south pole of permanent magnet i i. The other path may be traced as follows: the north pole of magnet iii, stator pole piece 8, core member l2, stator pole piece 5, diametrically across rotor member ii, the stator pole piece 5 back to the south pole of permanent magnet iii.

In view of the above described explanation, it is believed that it will now be clear that as the rotor member 2 rotates. the magnetic flux of the permanent magnets it. and la is alternately switched through the core members it and iii in opposite directions to cause induced voltages in the coils it and ii of alternating polarity. In order that the voltages induced in the magneto coils Ill and M may be as high as possible, the magneto rotor and stator teeth are so designed as to cause a very rapid change in the magnetic flux threading the core members i l and it, while the generator rotor member 2 is rotating between the positions shown in Figs. 1 and 2 of the drawing. In order to accomplish this the stator teeth 9 are, as shown, made very narrow so that their width is appreciably less than the width of the site standpoint. In the present arrangement this dimculty is obviated by utillzlnga plurality of parallel stator teeth on each pole piece so as to provide a plurality of parallel flux paths. Thus it will be noted that in the illustrated arrangement each of the stator pole pieces 55, 8, i and b is provided with tour inwardly extending stator teeth t3. This arrangement permits the required amount of pole piece cross-sectional area to conduct the required amount of magnetic flux without necessitating an undesirably long stator tooth. Obviously, the present invention is not limited to the illustrated arrangement wherein four teeth per pole piece are provided as other numbers of teeth may be used, depending on size and energy storage requirements of the magneto.

It will be noted that the breakerless magneto of the present invention is compact in design and has a symmetry which lends itself, in the illustrated arrangement, to the provision of the two output coils. These output cells may be advantageously used to energize an ignition system providing dual ignition for an engine having a cylinders, or single ignition for an engine having 212. cylinders. The number of impulses in each output coil per revolution of the rotor 2 is equal to twice the number of rotor teeth. Obviously by varying the number ofrotor teeth and by varying the relationship of the rotor speed to engine crankshaft speed, the voltage impulses may be timed relative to the spark discharges required for engines having any number of cylinders.

While we have shown and described particular embodiments of our invention, it will occur to those skilled in the art that various changes and modifications may be made without departing from our invention, and we therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention,

What we claim as new and desire to secure by Letters Patent of the United States is:

l. A breakerless magneto comprising a rotor It having salient teeth, a plurality of spaced arcuate rotor teeth l. While the expedient of making the stator teeth 9 narrow is desirable from the standpoint of obtaining a rapid flux change, it has the disadvantage that it reduces the cross-sectional area of the stator tooth for an axial length of the tooth of any given value. The amount of long stator tooth which is undesirable from. the

stator pole pieces disposed around said rotor, each of said stator members having a plurality of relatively narrow spaced teeth, core members and permanent magnets alternately arranged between adjacent pole pieces, and output coils wound around said core members.

2. A breakerless magneto comprising a ma netic rotor having salient teeth, spaced arcua te magnetic stator members disposed around said rotor, permanent magnets and magnetic core members interconnecting said stator members and arranged in alternate relation, each of said stator members having a plurality of spaced narrow teeth cooperating with the teeth of said rotor, and an output coil encircling each of said core members for producing high voltage impulses.

3. A magneto generator comprising a magnetic rotor member having salient teeth,two pairs of spaced arcuate magnetic stator members disposed around said rotor member, each stator member having a plurality of parallel narrow teeth cooperating with and of narrower width than the teeth on said rotor member, alternately arranged permanent magnets and core members disposed between adjacent stator members, and an output coil magnetically encircling each of said core members for producing high voltage impulses.

4. A magneto generator. of the inductor typ comprising a rotor member formed of magnetic material and having clrcumferentially disposed salient teeth, a stator member comprising a plurality of spaced arcuatepole pieces formed of magnetic material and disposed around said rotor member, each pole-piece having a plurality; of inwardly extending teeth cooperating with and? spaced from. said rotor teeth and being of nar- 6 rower width than said rotor teeth, a plurality of core members and a plurality of permanent mag-' nets arranged to magnetically connect adjacent ends of saidi'pole pieces, said core members andsaid magnets being alternately arranged around 10 said pole pieces and said magnets being arranged with their polar extremities abutting adjacent;

-pole-pieces, and a coil associated with each coref member, said stator and rotor teeth being so ar;-

ranged that rotation of said rotor member causes two low-reluctance magnetic circuit paths to be alternately established through said rotor memher. said stator pole pieces and said core members; whereby magnetic flux rrom said magnets alter-inately threads said core members in opposite di-' rections caujsing alternating voltages to be in-, duced in the/coils associated with said core members. i

5. a magneto generator of theinductor type comprising a rotor member formed of magnetic material and having -circumierentially disposed salient teeth. a stator member comprising iour,

spaced, arcuate. Dole Pieces formed or magnetic material and disposed around said rotor member, each pole piece having a plurality oi inwardly ex- 6' tending teeth cooperating with and spaced from said rotor teeth and being 01' narrower width than said rotor teeth. a pair of core members and a pair or, permanent magnets arranged to magnetically connect adjacent ends or said pole pieces, said core members and said magnetsbeing alternately arranged around said pole pieces and said magnets being arranged with their polar extremities abutting adjacent pole pieces, and a causing alternating voltages to be induced in the coils associated with said core members.

' EDWARD I". WARGIN.

JOSEPH .R. HARKNES.

assurances crrsn The following references are of record in the tile of this patent: I

UNITED STATES PATENTS Number Name Date 1,151,530 Neuland Aug. 24,1915 $116,353

Klaiber May 3, 1938

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