US2604499A - Electrical apparatus - Google Patents

Description

y 1952 c. G. BUCKLEY 2,604,499

ELECTRICAL APPARATUS Filed Sept. 28, 1949 2 SHEETS -Sl-1EET l INVENTOR.

BY $1 41 41 6M1 Dale, a. 6M

ATTORNEY.

July 22, 1952 c. e. BUCKLEY ELECTRICAL APPARATUS 2 SI'IEETSSI-IEET 2 Filed Sept. 28, 1949 INV TOR.

ATTORNEY.

Fig). 8 By fih n 5. 54x15 Patented July 22, 1952 UNITED STATES PATENT OFFICE ELECTRICAL APPARATUS Clayton G. Buckley, Sidney Center, N. Y., as-

signor to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application September 28, 1949. Serial No. 118,309

12 Claims. 1

"This invention relates to electrical apparatus and more particularly to magnetos and parts thereof for generating electrical energy.

One of the objects of the present invention is to provide a novel magneto generator of the rotary flux distributor type which is particularly adapted for use in the ignition systems of engines having only a small number of cylinders. I

Another object is to provide in a magneto generator a novel magnetic flux distributing system which results in a novel magnetic flux pattern through the coil. V

A further object is to provide a novelly constructed magnetic rotor for use in a magneto generator which is capable of producing greater energy than prior structures of comparable size.

Still another object is to provide novel apparatus of the above character which is adapted to produce only one impulse per coil during each revolution of the rotor which can create a spark effective to ignite a charge in the cylinder of an engine. 7

A still further object is to provide a novel magneto generator for the ignition system of an engine wherein a magnetic rotor is driven at crankshaft speed without danger of producing any socalled maverick sparks which are harmful to proper operation of the engine. 1

Another object is to provide a magneto generator which operates in a novel manner to minimize undesirable magnetic flux changes without appreciably diminishing the extent of the useful flux changes. I e x A The above and further objects'and nbVelfeatures of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, how ever, that the drawings are for the purpose of illustration only and are not intended to define thelim'its of the invention.

In the drawing, wherein like reference characters refer to like parts throughout the several views,

Fig.1 is an end elevation viewoi one form of Jmagneto generator embodying the present ine t .l 7..

Fig. -2 is a similar view, with parts broken away,

of one embodiment of the novel magnetic rotor I flux and voltage curves for the device of Fig. -1.

.The single embodiment/0f the invention illus tread in the drawings, by way of example, is

shown in the form of magneto generator adapted for use in 'theigni'tion system of a one or two cylinder engine. 'In such systems the rotor of the magneto is usually driven at the same speed as "the crankshaft and the ignition coil is connected directly to the spark plug in the engine cylinder. In ignition systems of this type heretofore known it has not been possible to prevent undesired or so-"call'ed maverick sparksin the engine cylinders without complicating the system or diminishing energy of the desired spark impulses. The present construction obviates these difficulties.

In the form shown the magnetic rotor ID is adapted to be keyed or otherwise suitablysecured to an engine crankshaft (not shown) for rotation therewith. A single lobe circuit breaker cam l 'I may be seeured'to either the rotor or them-- gine crankshaft "for-rotation at the same speed. The remaining parts of the magneto are preferably mounted in a casin 12 which may be secured to an engine casing in any known manner, preferably for angular adjustment about the axis of rotation of the rotor.

Mounted in'casing l2 for cooperation with rotor l U and completing the magnetic flux conducting system are a pair of stator pole shoes, [4 the centers of the faces of whichare angularly spaced approximately ninety degrees. The outer ends of the pole shoes are magnetically connected "by the core I 5 of a transformer coil 16. 'The windings of 'saidcoil may be connected in any known and suitable manner in circuits with a spark plug (not shown) a circuit breaker l1 and a condenser l8. shown, the primary winding is connected by a lead T9 and spring 20 to the insulated contact of the circuit breaker, said contact beingmounted on 'pivotedlever 2i which engages the surface of cam 'l'l. Saidwinding is also connected to condenser 18 through leads l9 and 22. The other terminal of the condenser and the'other contact of the circuit breaker mounted on a bracket 23 are grounded to'the casing l2.

The'o'p'p'o'site end of the primary Windingand one ends: the "secondarywinding of the trans- ;formei coil may be grounded through a lead'ifl. The high potential end "of the secondary windingm'ay be connected through a lead 26 to the insulated term nus: a spark plugin the engine "cylind'ei o'r' other poi ter use.

A duplicate set of the above Tpa'r't's "disposed from those described are provided for use when a two cylinder engine is to be operated. These are identical parts and a further detailed descripti'o'n thereof is believed to be unnecessary. It will be seen that the two "coils will deliver alternate impulses at 180 intervals of rotor rotation. v A novel four pole magnetic rdtoris rovided for cooperationwith the'two'pole stator for attaining the desired 'n'ovel results heretofore-men- "tion'ed. The sepecinc construction shown comprises a non-magnetic end plate with an axially extending hub 3| which engages the engine crank shaft or other driving shaft. Secured to end plate 38 by means of rivets 32 and a nonmagnetic plate 33 are four equally spaced pole shoes 34. Interposed between and held in place by pairs of adjacent pole shoes 34 are three bar magnets 35, 38, and 3'! of substantially equal strength and a spacer 38 of non-magnetic metal, such as brass, each said pole shoe forming a pair with each of the pole shoes circumferentially adjacent thereto. Each of the magnets is longitudinally magnetized with a north pole N at one end and a south pole S at the other end. Circumferentially speaking, the three magnets are arranged in series, for example with the south pole of each magnet leading its north pole in the direction of rotation. As will be more specifically pointed out hereafter, this novel rotor construction results in a flow of static magnetic flux in one direction through core l5 during three fourths of each revolution of the rotor and in the other direction during only one quarter of each revolution, so as to reduce to an insignificant magnitude all of the flux changes except one during each revolution of the rotor.

In the graph of Fig. 8, the heavy black curve 60 represents an approximation of the static flux in coil core l5 during one complete revolution of the rotor from the 0 (or 360) position of the rotor shown in Fig. i. In this position the lines of magnetic flux flow through magnet 35 and the stator I4, [5 in a clockwise or positive direction. At this time magnets 36 and 3'! do not contribute appreciably to the flow of flux through the stator since the same are open circuited by the spacer 38. As the rotor turns in the direction of the arrow, the active rotor poles move out from under the stator pole shoes resulting in a relatively minor diminution of the flow of magnetic flux until the succeeding rotor pole shoe moves into overlapping relation with the left hand stator pole shoe 14. At this time the flux increases again to a positive maximum at the 90 degree position (Fig. 5) when the flux flows through magnet 36 and the stator in a clockwise direction. The change of flux represented by the dip 4| in curve 40 between the zero and ninety degree positions is so small and gradual as to be incapable of generating a sufiicient voltage in the secondary winding of the coil to cause a spark at the spark plug. This operation is repeated during the next ninety degrees of rotation as magnet 3! moves into position (Fig. 6) to furnish the fiux of the same polarity.

During the next ninety degrees of rotor movement a reversal of flux through stator l4, [5 occurs, the same changing from a positive maximum at 180 to a negative maximum at 270. In the latter position the flow of flux is in a counterclockwise direction through the stator and all three of the magnets in series. It is this large change of flux which is utilized for producing the single desired sparking of the spark plug to thereby obtain a timely ignition of the charge in the engine cylinder. Accordingly, the parts are so arranged that the contacts ofthe circuit breaker H are permitted to engage and thereby complete a circuit through the primary winding of coil l6 about when the rotor is in the position C (Fig. 8), that is, just prior to the position of Fig. 6 and when the flow of magnetic flux is at a substantial maximum. Current then begins to flow in said winding and tends to buck or prevent any change of flux, so that in normal operation of the magneto the resultant or dynamic flux varies from the so-called static flux and is represented by the broken line curve 44. When the rotor reaches the so called E gap position, the cam disengages the contacts of circuit breaker I! thereby opening the primary circuit so the flow of current ceases. Thereupon,- the fluX changes abruptly from nearly a positive maximum to a substantial negative magnitude, thus generating a desired voltage in the secondary circuit. This voltage is diagrammatically represented by the curve 42.

The magnetic flux attains a negative maximum at the 270 position of the rotor and another flux reversal is efiected during the last of rotation of the rotor. At high speeds this change of flux may be sufficient to create a substantial maverick voltage in the secondary circuit as indicated by the curve 43. However, this voltage is generated during the power stroke of the engine piston when the pressures within the combustion chamber are very high and when there are little or no unburned combustible gases in said chamber. The high pressure tends to prevent sparking of the spark plug at this voltage and in any event if a spark is generated the same is not detrimental to the operation of the engine. The exact point of ignition for best engine operation depends upon the design of the engine but in all engines ignition is caused to occur within a range of shortly before or shortly after the piston reaches top center, that is, the end of its compression stroke. Since ignition occurs at the position of the voltage represented by curve 42, it will be clear that the maverick 43 will occur during the early portion of the power stroke of the engine piston and before any fresh combustible gases are drawn into the cylinder of a two stroke cycle engine.

By reason of the fact that all three magnets of the rotor are placed in series (Fig. 7) during the useful reversal of flux in the stator and coil, thereby increasing the available coercive force for overcoming the reluctance of the magnetic circuit, more abrupt and rapid flux change occurs than it is possible to obtain with known constructions of comparable size and weight. This results in a higher secondary voltage. Additionally, this novel rotor construction provides advantages with respect to the selection of materials for the magnets and hence with respect to cost and manufacturing.

There is thus provided novel apparatus for generating electrical energy, such as for engine ignition systems and the like, said apparatus being so constructed as to obviate the danger of pro-ignition in the engine cylinders by so-called maverick sparks. Additionally, an apparatus of given size and weight constructed in accordance with this invention is capable of producing greater peak voltages in the secondary winding of a transformer than has been possible with prior devices of comparable size and weight. The novel mode of operation of the structure contemplated by the invention renders it possible to take fullest advantage of the energy producing potential of the device and permits the designer a wider selection of materials without sacrificing power and efiiciency.

Although only a single embodiment of the invention is illustrated in the drawings and described in the specification, it is to be expressly understood that the invention is not so limited; neither is the invention limited in its use to a magneto of the type embodied in an ignition system but may be adapted for other uses where electrical energy is required. Various changes may also be made in the design and arrangement of the parts illustrated and in the kinds of materials suggested Without departing from the spirit and scope of the invention, as will now be understood by those skilled in the art.

What is claimed is:

1. A magneto generator comprising a coil, a magnetic flux conducting stator including a core through said coil and a pair of pole shoes connected by said core, and a magnetic rotor having circumferentially spaced pole shoes in operative relation with said stator pole shoes, said stator pole shoes and successive rotor pole shoes being about equally angularly spaced and said rotor including non-magnetic means in the space between two adjacent rotor pole shoes and polarized magnetic means bridging each of the other spaces between adjacent rotor pole shoes, said magnetic means being arranged magnetically in series around the axis of rotation of the rotor.

2. In apparatus of the class described, a magnetic rotor comprising four pole shoes equally spaced around the axis of rotation, and a stator comprising two pole shoes spaced for successive cooperation with pairs of adjacent rotor pole shoes, each of the spaces except one between successive rotor pole shoes being bridged by polarized magnetic means and said magnetic means being arranged magnetically in series.

3. In apparatus of the class described, a coil, a stator traversing said coil, and a magnetic rotor having a plurality of circumferentially spaced pole shoes operatively associated with said stator, said rotor comprising a plurality of magnets arranged magnetically in series relation between successive rotor pole shoes around the axis of rotation.

4. In apparatus of the class described, a coil, a magnetic flux conducting stator traversing said coil, a magnetic rotor operatively associated with said stator and comprising a plurality of pole shoes and a plurality of magnets arranged magnetically in series around the axis of rotation, one said magnet being positioned between each except one set of adjacent races of adjacent pole shoes, whereby the direction of flow of magnetic flux through the stator is continuously in one direction during a major portion of each revolution of the rotor, circuit breaker means in circuit with said coil, and means for closing and then opening said circuit breaker means while the flow of magnetic flux is at a substantial maximum in one direction. 1

5. In apparatus of the class described, a magnetic flux conducting stator having a pair of pole shoes, and a magnetic rotor comprising a plurality of pole shoes equally spaced around the axis of rotation thereof for cooperation in pairs.

with said stator pole shoes, said rotor comprising polarized magnetic means between all but one pair of adjacent rotor pole shoes and arranged magnetically in series, whereby magnetic flux flows through said stator in one direction during at least (360n degrees of each revolution of the rotor, where n is the number of degrees between the centers of adjacent rotor pole shoes.

6. In apparatus of the class described, a magnetic flux distributing rotor having a plurality of circumferentially spaced pole shoes and a plurality of magnets all of which are arranged magnetically in series around the axis of the rotor and positioned between successive adjacent pole shoes, and a magnetic flux conducting stator having poles spaced to cooperate with said pole shoes during rotation of the rotor.

7. In a magneto generator having a magnetic flux conducting stator and a magnetic flux distributing rotor operatively associated therewith said rotor having a plurality of circumferentially spaced pole shoes, each said pole shoe forming a pair with each of the pole shoes circumferentially adjacent thereto, and a plurality of magnets all arranged magnetically in series around the axis of rotation, there being at least one magnet between each pair of adjacent pole shoes except one pair.

8. In apparatus of the class described, a magnetic flux distributing rotor having a plurality of circumferentially spaced pole shoes and a plurality of magnets arranged magnetically in series, all of said magnets and pole shoes forming a continuous metallic magnetic path extending throughout a major portion of a circumference around the axis of rotation from one pole shoe to the pole shoe adjacent thereto, said last-named adjacent pole shoes being of opposite polarity.

9. A magnetic rotor for a magneto generator comprising four equally spaced magnetic flux conducting pole shoes, three bar magnets interposed between and magnetically connecting successive pole shoes, said magnets being arranged magnetically in series, a non-magnetic spacer interposed between the pole shoes at the opposite ends of said magnet series, and means for securing said pole shoes, magnets and spacer in assembled relation.

10. A magnetic rotor for a magneto generator comprising a plurality of circumferentially spaced pole shoes, non-magnetic means in the space between two adjacent pole shoes, and flux producing magnetized means bridging each of the other spaces between adjacent pole shoes around the axis of rotation.

11. A magnetic rotor for a magneto generator comprising a plurality of circumferentially spaced pole shoes, non-magnetic means interposed between two adjacent pole shoes, and a magnet connecting each other pole shoe to each pole shoe adjacent thereto, said magnets being arranged magnetically in series around the axis of the rotor.

12. A magnetic rotor comprising a plurality of pole shoes, and a spacer interposed between each pole shoe and the adjacent pole shoes on opposite sides thereof, one of said spacers being nonmagnetic and the remainder being magnetized and arranged magnetically in series around the axis of the rotor.

CLAYTON G. BUCKLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,060,259 Spengler Nov. 10, 1936 2,233,946 Harmon Mar. 4, 1941 2,392,500 Phelon Jan. 8, 1946 FOREIGN PATENTS Number Country Date 529,107 Great Britain Nov. 14, 1940 438,932 Germany Mar. 7, 1927

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