US2528687A - Arrangement of stator-platemounted elements of a flywheel magneto - Google Patents

Description

Nov. 7, 1950 A. L. BROWNLEE EIAL 2,528,687

ARRANGEMENT OF smmxmmmmounmn ELEMENTS OF A FLYWHEEL MAGNETO Filed Dec. 8, 1949 2+ [Msuur/o/v [NJl/LA now INVENTOR ALuzwL bli'omuzz AND ZZ'RRz/Ycz G. .L 00/6 ATTOR EYS Patented Nov. 7, 1950 UNITED STATES PATENT. OFFICE ARRANGEMENT OF STATOR PLATE- MOUNTED ELEMENTS OF A FLYWHEEL MAGNETO Application December 8, 1949, Serial No. 131,732

1 Claims.

This invention relates to an improved arrangement of such elements of a flywheel magneto as are mounted on the stator plate, that is, all the magneto elements except the magnet and its pole shoes which are fixed to the flywheel.

Magnetos of this type are commonly used with the relatively small internal combustion engines which serve as outboard motors for boats. In some cases, such engines are of the two-cylinder, two-cycle, alternately-firing type and it is desirable that the magneto for such an engine should have two separate ignition units, that is two separate coil-bearing core structures, for cooperation with the magnetic rotor formed by the flywheel. In such a case, two breaker mechanisms and two condensers are required, one for each ignition unit. In other cases, one core structure may bear a low tension coil for generating lighting current, while the other core structure or structures may bear an ignition coil or coils. In every case, there will be at least two coil-bearing core structures and at least one breaker mechanism. The problem is to mount all the necessary elements on a stator plate, which is adapted for use with small flywheels (frequently no more than six and one half inches in diameter), without adding to the overall dimensions of the magneto so as to require changes in the flywheel.

This invention is an improvement on that disclosed in Patent No. 2,447,727, granted August 24, 1948, on an invention of Albert 1. Alstrom and Allen L. Brownlee and assigned to the assignee of the present invention.

The mechanism of said patent has been used successfully and satisfactorily with outboard motors at speeds up to about 4200 R. P. M. but for motors operating at higher speeds, approaching 5000 R. P. M. or above, said mechanism has certain disadvantages which the present invention seeks to overcome. A breaker mechanism of lower inertia is needed and one in which the movable breaker point is not carried by the radially-movable cam-actuated plunger of said patent.

It is an object of this invention to mount the breaker mechanism in the narrow radial gap between two adjacent core structures and to mount in the most narrow portion of such gap a radially-slidable plunger, as in the prior patent, and also to provide in the outer and wider portion of such gap a pivoted 'U-shaped breaker lever having short parallel arms, one of which lies at right angles to and is actuated by" the pin: er and the other of which carries a breaker point confronting a stationary breaker point carried by an ear on the plate that retains the plunger in its slideway.

This object will best be understood from the description of one illustrative example of the invention in the accompanying drawings, in which:

Fig. 1 is a top plan view of a stator plate embodying the invention;

Fig. 2 is a fragmentary sectional elevational view taken on line 22 of Fig. 1 and drawn to a larger scale;

Fig. 3 is a fragmentary view taken similarly to Fig. l but drawn to a larger scale;

Fig. 4 is a fragmentary sectional plan view taken on the line 44 of Fig. 2; and

Fig. 5 is a fragmentary sectional elevational view taken on the line 5-5 of Fig. 3.

Referring to these drawings: there is shown at l in Fig. 2 a portion of the. upper end of the crankcase of a small internal combustion engine, such for example, as that used as an outboard motor for boats. The crankcase has an external hub 2, through and beyond which one end of the engine crankshaft 3 extends. The stator plate includes a substantially circular bottom wall 4 from which upstands in coaxial relation a hollow hub 5. This hub 5 telescopes over the crankcase hub 2 and closely fits the same to support the stator elements of the magneto, and particularly the pole pieces, in true coaxial relation with shaft 3. The hub 5 may be held to hub 2 by any suitable means, herein shown as leather plug 6 mounted in wall 4 for radial sliding movement and pressed inwardly against the bottom of a circumferential groove 7 in hub 2 by means of a spring 8, which is adjustable by a screw 9, threaded into the stator plate and closing the hole in which the plug and spring are mounted. The arrangement holds hub 5 in axial position on hub 2 and also holds it frictionally against turning on hub 2, enabling it to be turned, when desired, for the purpose of advancing or retarding the spark in the usual manner. The stator plate also includes an annular rim 10, extending upwardly from the bottom wall 4 and an annular flange ll, turned outwardly from the upper 'end of rim Iii. This flange H is intended to cooperate with the engine flywheel, when in place on shaft 3, to provide an enclosure for the magneto parts, as shown in the abovenamed patent.

The stator plate (Fig. 1) supports a plurality of core structures, in this case two, which are angularly spaced about hub 5. These core structures may vary considerably in form. As herein shown, each core structure includes three more or less radial legs l2, l3 and I4, the inner ends of which are interconnected as at [5. The outer ends of the legs l2, l3 and I4 of each core struc ture form pole pieces for cooperation with the pole shoes of the magnetic rotor, as shown in said patent. The intermediate leg l3 of each core structure forms a core, bearing suitable windings, in this case primary and secondary coils l6 and I1, respectively, since two high tension ignition units are desired. But in some cases one core structure might equally well bear a single low tension winding to be used for lighting purposes. Each core structure is made up of iron laminations, held together by rivets I 8 and clamped to supporting pads i9, which project upwardly from the bottom wall 4 of the stator plate, by screws 20.

The two core structures are located in opposed relation. The legs I2 and I4 and the connecting part I5 of each core structure are arranged in adjacent relation and are separated by narrow gaps which extend radially of the stator plate. The space between the central portions of the two parts I5 is substantially less than the diameter of either hub 2 or 5. It is necessary in order to avoid undue electrical leakage losses to keep each metallic and grounded core structure spaced away from the secondary coil [1 thereon. Because of this, a space, such as 2|, is necessary betweenthe inner end face of each secondary coil ll andthe adjacent legs I2 and 14 of the core structure. Therefore, the narrow radial space between the two core structures is constricted intermediate its ends at locations opposite theinner ends of the secondary coils l1. Beyond this constriction, the core structures diverge outwardly to some extent, as permitted bythe location of the pole pieces on the ends of legs 12 and I4.

The space limitations are such as to preclude straddle the ear 28.

the use of the common type of breaker mech- 7 anism, that is the type having a pivoted bellcrank with widel diverging arms, the outer end of one of which carries a breaker point and the outer end of the other Of which rides directly on the actuating cam. Such a breaker mechanism could not be located between the two closelyspaced core structures described and, if located outwardly beyond the core structures, it would i mean an increase in the axial dimensions of the magneto, which is undesired. The breaker mechanisms need to be kept between the limits of two transverse planes, one of which passes through the outer end face of hub 5 and the other of which passes through the outer end faces of the core structures. To keep the breaker mechanisms within these limiting transverse planes, they must be made in a special manner and be located in the above described narrow radial gaps. In the present case, where both stators are used for ignition, two breakers are necessary but if one stator is used for a purpose which does not require a breaker mechanism, one of the mechanisms shown may, of course, be omitted.

. Upstanding from wall 4 of the stator plate and located, one in each of the two most narrow portions of the radial gaps between the two core structures, are supports 22. Each support has a deep and narrow slot located radially of the plate and forming a slideway to slidably receive a reciprocable slide 23, and a wide and shallow slot in its upper end to receive a fiat and relatively thin retaining plate 24 for the slide. This plate is held to the support 22 by means of a 4 screw 25, passing through a longitudinal slot 26 in the plate and threading into the support. The plate 24 holds the slide 23 against vertical movement in its slot and slidably engages the upper face of the slide. One end of slide 23 is adapted to ride on a cam 21, fixed to shaft 3, and the other end is adapted to engage and actuate the breaker arm of the breaker mechanism. The slide is desirably made of laminated phenolic material to provide for a long life of useful service under'severe operating conditions.

The breaker mechanism is supported entirely fromthe plate 24, which extends beyond the support 22lfor this purpose and has an ear 28 turned downwardly at right angles therefrom and bearing the fixed breaker point 29. Plate 24 is offset laterally (Fig. 1) to support a stud 30, which is fixed at one end to the plate and extends downwardly therefrom to support the breaker arm. The offset portion of plate 24 extends outwardly beyond the stud 38 at an acute angle to the plane of movement of slide 23 and terminates witha downturned ear 3|, having a seat 32 for the outer end of the breaker spring 33. The breaker arm is made of any suitable insulating material. ,It is substantially U-shaped, having two short and closely-spaced parallel arms 34 and 35 (Fig. 4), interconnected at one end by a portion 36, which is pivotally mounted on stud 3B. The. arm 34 carries on one side a breaker point 3'l,to cooperate with breaker point 29 and, on the other side, a flexible conductor 33, secured to the arm bythe same rivet which holds the breaker point 3'! to the arm. The breaker arms 34 and 35 The spring 33 acts on arm 34 with a tendency to hold the breaker points 29 and 31 engaged. The slide 23, when moved radially outward by cam 21, acts on arm 35 to separate the breaker points.

The spring 33 may, and preferably does, act to hold the breaker arm in axial position on its fule c'rum stud 30. As best shown in Fig. 5, the ear 3! is bent at an angle slightly less than ninety degrees to the plate 24, say The arm 34 has a face 38 arranged at a similar angle to its upper fiat face and on this face is a projection 39 to fit within one end of spring 33, just as the projection 32 fits within the other end of spring 33. These projections 32 and 39 hold spring 33 so that its axis'lies normal to the ear SI and face 38. Thus, of the force exerted by the spring 33 on the breaker arm, there is an upward vertical component which presses the arm vertically upward against a washer 46 on stud 30 and the washer against the bottom face of plate 24.

Associated with each breaker mechanism is the usual condenser which is electrically connected across the breaker points 29 and 31 in the usual manner. This condenser is contained in a metallic cylindrical casing 4i to which one terminal of the condenser is connected. The lower end of this casing lies in a hole formed in the stator plate and isheld in place by screw 42, which clamps an car 43 on the casing to such plate. The other termi nal of the condenser is connected to a central metallic post 44, upstanding from the upper and insulated head 45 of easing 4!. The flexible conductor 38 is secured to this post 44 by a screw 48.

The part 41 is a piece of felt fixed at one end in the support 22 and having its other end engaging the cam 21. This felt is saturated with oil and serves to wipe the cam clean and to'lubricateit- Some of the oil'on the cam reaches'the inner end of plunger 23, and works it way along the plunger into the slot in support 22 to lubricate the plunger.

Adjustment of the breaker points is effected by moving the plate 24 radially while screw 25 is loosened. With cam 21 positioned for its high point to engage the inner end of the plunger and a feeler gauge inserted between the breaker points 29 and 31, the plate 24 is moved until the inner end of the plunger engages the cam and the outer end of the plunger engages arm 35. The screw 25 is then tightened to hold the plate in adjusted position and the feeler gauge is removed.

It is desirable to provide means for-preventing the plunger 23 from sliding out of the slideway in support 22 when the plunger is not engaged with its actuating cam, as when the stator plate not in place on its support. This may be done simply by a small projection 48 extending downward-1y into a slot 49 in the upper edge of the plunger as shown in Fig. 2. A similar slot may be formed in the bottom edge of the plunger 50 that the latter may be placed in its guiding slot either 2 edge up and still work properly. Sometimes, the inner end of plunger 23 is concaved to fit cam 21. In such cases, the slots 49 are located unsymmetrically between the ends of the plunger to compel the operator to place the concaved end so as to engage the cam. Except for this, the slots could be located symmetrically so as to be reversible.

The electrical connections of the magneto have not been shown or described as they are unnecessary to an understanding of the invention which consists in a special arrangement described of the parts which are carried by the stator plate. Reference to said patent may be had for a disclosure of such connections if necessary or desired.

The construction of the magnetic rotor and its cooperation with the core structures of the stator may be as disclosed in said patent. Reference is also made to said patent for the operation of the magneto if such is necessary or desired.

This invention is characterized by an arrangement of parts on the stator plate of a flywheel magneto that enables the use of a plurality of core structures with breaker mechanisms and condenser casings for each such structure mounted within the narrow space limits of diameter and axial length that are available inside a small flywheel of the kind described. The ne essary additional parts are provided without relocation of the breaker cam and without increase in diameter of the flywheel or in the axial length of the same. The breaker mechanism are located entirely between tWo transverse planes, one of which includes the outer end i ace of hub and the other of which includes the outer end face of each core structure, as is necessary if relocation of the breaker cam is to be avoided. This is made possible by the use of a radially reciprocable plunger of thin rectangular cross section located in the most narrow part of one of the radial gaps between adjacent core structures to connect the breaker cam with a special form of breaker lever which can be mounted in the outer and wider portion of such radial gap and supported by and be" neath an extension of the plate used to retain the plunger in its slideway.

The structure disclosed is an improvement over that of said patent in that alignment of the breaker points is not dependent on a close fit cf the actuating plunger in its slideway. This plunger is subjected to some side thrust by cam 21 and, unless it closely fits its slideway, it swing out or" true radial position. In the arrangement of the patent, this would cause the movable breaker point to be moved out of parallel relation with the fixed breaker point. In the present con struction, a close fit of the plunger in its slideway is not necessary and any swinging of the plunger away from true radial position cannot swing the movable breaker point because the latter is carried by a separate lever.

What is claimed is:

1. In combination, a stator plate for a flywheel magneto, said plate having a hollow hub with an opening and being adapted to be mounted on that hub of an engine crankcase through and beyond which the engine crankshaft extends, a pair of coil-bearing core structures fixed to said plate on opposite sides of the axis of the firstnamed hub, said core structures being mounted in opposed relation with their inner walls in adjacent relation but separated by generally radial gaps, said inner walls in a radial location near the opening in the first-named hub being separated by a distance substantially less than the diameter of said opening and from said location diverging outwardly to their outer ends which are separated by a substantially greater distance, said plate having a portion upstanding therefrom into the more narrow portion of one of said gaps and having a slot therein of rectangular cross section disposed radially of the plate, a plunger of similar cross section slidably mounted in said slot, a plate secured to said portion and confining the plunger in its slot, said confining plate having a downturned ear bearing a breaker point and having a part oilset laterally to one side of said ear and extending into the wider portion of said one gap, a stud fixed to and depending from said part, a U- shaped breaker lever pivotally mounted at its mid portion on said stud with its two arms straddling said ear, a breaker point on one of said arms confronting and engageable with the first-named breaker point, the other of said arms being engageable by said plunger to separate the breaker points, and a spring acting on the lever to move it to engage the breaker points.

2. In combination, a stator plate for 9, flywheel magneto, said plate having a hollow hub with an opening therein and being adapted to be mounted on that hub of an engine crankcase through and beyond which the engine crankshaft extends, a pair of coil-bearing core structures fixed to said plate on opposite sides of the axis of the first-named hub, said core structures being mounted in opposed relation with their inner walls in adjacent relation but separated by gen rall radial gaps, said inner walls at a radial location near the opening in the first-named hub being separated by a distance substantiall less than the diameter of said opening and from said location diverging outwardly to their outer ends which are separated by a substantially greater distance, said plate having a portion upstanding therefrom into the more narrow portion of one Of said gaps and having a slot therein of rectangular cross section disposed radially of the plate, a

" plunger of similar cross section slidably mounted said car, a breaker point on one of said arms confronting and engageable with the first-named breaker point, the other of said arms being engageable by said plunger to separate the breaker points, and a spring acting between the lastnamed ear and said lever to move the latter to engage said breaker points.

3. In combination, a stator plate for a fiywheel magneto, said plate having a hollow hub with an opening therein and being adapted to be mounted on that hub of an engine crankcase through and beyond which the engine crankshaft extends, a pair of coil-bearing core structures fixed to said plate on opposite sides of the axis of the first-named hub, said core structures being mounted in opposed relation with their inner walls in adjacent relation but separated by generally radial gaps, said inner walls at a radial location near the opening in the first-named hub being separated by a distance substantially less than the diameter of said opening and from said location diverging outwardly to their outer ends which are separated by a substantially greater distance, said plate having a portion upstanding therefrom into the more narrow portion of one of said gaps and having a slot therein of rectangular cross a section disposed radially of the plate, a plunger of similar cross section slidably mounted in said slot, a plate secured to said portion and confining the plunger in its slot, said confining plate having a downturned ear bearing a breaker point and having a part offset laterally to one side of said ear and extending into the wider portion of said one gap, a stud fixed to and depending from said part, said part having an ear downturned from its outer end at an angle slightly less than ninety degrees, a U-shaped breaker lever pivotally mounted at its mid portion on said stud with its two arms straddling said ear, a breaker point on one of said arms confronting and engageable with the first-named breaker point, the other of said arms being engageable by said plunger to separate the breaker points,

said lever having a face paralleling the lastnamed ear, and a coil spring acting between the latter and said face to move the lever to engage said breaker points and exerting an upward thrust on the breaker lever to retain it in axial position on said stud.

4. In combination, a stator plate for a flywheel magneto, said plate having a hollow hub with an opening therein and being adapted to be mounted on that hub of an engine crankcase through and beyond which the engine crankshaft extends, a pair of coil-bearing core structures fixed to said plate on opposite sides of the axis of the first-named hub, each said structure including three legs interconnected at their inner ends near said axis and extending outwardly in angularly spaced relation terminating with curved polar surfaces coaxial with said hub, said core structures being mounted in opposed relation with their inner walls in adjacent relation but separated by generally radial gaps, said inner walls at a radial location near the opening in the first-named hub being separated by a distance substantially less than the diameter of said opening and from said location diverging outwardly to their outer ends which are separated by a substantially greater distance, said plate having a portion upstanding therefrom into the more narrow portion of one of said gaps and having a slot therein of rectangular cross section disposed radially of the plate, a plunger of similar cross section slidably mounted in said slot, a plate secured to said portion and confining the plungerin its slot, said confining plate having a downturned ear bearing a breaker point having a part offset laterally to one side of said ear and extending into the wider portion of said one gap, a stud fixed to and depending from said part, a U-shaped breaker lever pivotally mounted at its mid portion on said stud with its two arms straddling said ear, a breaker point on one of said arms confronting and engageable with the first-named breaker point, the other of said arms being engageable by said plunger to separate the breaker points, and a spring acting on the lever to move it to engage the breaker points.

5. In combination, a stator plate for a flywheel magneto, said plate having a hollow hub with an opening therein and being adapted to be.

mounted on that hub of an engine crankcase through and beyond which the engine crank-- shaft extends, a pair of coil-bearing core structures fixed to said plate on opposite sides of the axis of the first-named hub, said core structures being mounted in opposed relation with their inner walls in adjacent relation but separated by generally radial gaps, said inner walls at a radial location near the opening in the first-named hub being separated by a distance substantially less than the diameter of said opening and from said location diverging outwardly to their outer ends which are separated by a substantially greater distance, said plate having a portion upstanding therefrom into the more narrow portion of one of said gaps and having a slot therein of rectangular cross section disposed radially of the plate, a plunger of similar cross section slidably mounted in said slot, a plate secured to said portion confining the plunger in its slot, said 0011-.

fining plate having a downturned ear bearing a breaker point, a condenser casing fixed to and upstanding from said stator late at a location spaced radially outward from said ear and in the wider part of said one gap near one of said inner walls, said confining plate having a part offset laterally to one side of said ear and extending into the wider part of said one gap with its outer end located between the condenser casing and the other inner wall, an ear downturned from the outer end of said part, a stud fixed to and depending from said part near its inner end, a U- shaped breaker lever pivotally mounted atits mid portion on said stud with its two arms straddling said ear, a breaker point on one of said arms confronting and engageable with the first-named breaker point, the other of said arms being engageable by said plunger to separate the breaker points, and a spring acting between the lastnamed ear and said lever to move the latter to engage the breaker points.

ALLEN L. BROWNLEE. TERRENCE G. LOUIS.

REFERENCES CITED UNITED STATES PATENTS Name Date Alstrom Aug. 24, 1948 Number

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