US1674050A - Magneto - Google Patents

Description

A June 19, 1928.

T. G. LOUIS MAGNETO Filed Sept. 3, 1926 INVNTOR j ATTORNEYJ Patented June 19, 1928.

UNITED STATES PATENT OFFICE.

'TERRENCE G, LOUIS, or s,PRIN@FIELDA7` MASSACHUSETTS, ASSIGNOR To "WI'C'O LEC- TRIC COMPANY, oF WEST SPRINGFTEL'D, MASSACHUSETTS, A CoRPoRATIo or MASSACHUSETTS.

This invention relates to magnetos and is particularly directed to improvements m the "mechanism for actuating. the armature of a magneto. v Y c rlhefinvention has to do primarily with magnetosof the So-called reciprocating armature type, wherein an armature 'is periodically moved toward and `away from magnetic poles to vary thereluctance ot'a magnetic circuit. Usually and preferably, the armature, when moved toward said poles, is also brought into contact therewith. 4it has been customary heretofore to move the armature toward and into contact with its poles bythe expansive eHort oit a return spring, which acts to accomplish Athis purpose as and when :permitted by the mechanism used to unseat the armature fromy itspoles and drive it Away from the latter. Such mechanism, for n'iagnetoswhich are driven at high engine speeds, may consist simplyofa. cam or any other means tor effecting an inelastic transmission ot torce from the drive shaft ot the magneto to the armature. -However,

' it is usual, even `in such magnetos to supplement such drive by a Yspringr drive which maybe optionally used on starting or at low engine speeds. The spring drive always used t'or magnetos, which are eriven at low yengine speeds. In vthe spring drive a Spring, initially insufficiently stressed to overpower theforce of magnetic attraction tending to hold thearmature to its poles, is periodically placed under stress, and allowed to act on the armature to move it away from its poles. Usually, this Spring, even when fully stressed, is insufficient to overpower the magnetic hold on the armature and comes into play only after such hold has been broken by an inelastic transmission of force from the driveshaft, after which the spring expands and moves the armature at a speed independent of engine speed. The magneto is arranged to producev a Spark during the flight of the armature away from its poles and up tothe time of the production of the spark (when the breaker points open) it is desired to move the armature as rapidly as possible. Y

This invention is directed to, and has for one object, the elimination of the opposing force of the return spring during the initial Stage of the flight of the armature away from its poles. i

` MAGNETO.

Application filed September, 1926. Serial No. 133,493.

netic attraction.

Another object of the invention -isto provide` an arrangement whereby Ythe spring, which customarily serves toyieldingly hold the breaker points ofthe interrupter closed, maybe utilized for the additional 'function of moving the armature in the initial stage ot its return flight and whereby the breaker points themselves may serve by their en gagement as positive stops to prevent the spring from opposingl thel armature driving iorce during theinitial stage of its Hight away from the poles. l y

According to the last named object, there is an advantage due to the elimination of parts by making certain parts perform two functions and thereis also the advantageo'l perfect coordination in timing because the return spring cannot oppose the downward movement ot the armature until the breaker points open at whichtime the active part ol the downward movement ot' the armature (that part effective to producethe spark) has been completed.

Other objects and features ot' the invention will appear in the following description vand will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanying drawings, in which l Fig. 1 is a front elevational view of a magneto embodying the invention;

Fig. 2 is a sectional plan view taken on the line 2-2 of Fig. 1, showing the armature drivingmeehanism as arranged for spring drive;

Fig. 3 is a fran-,mentary view, taken similarly to Fig. 2 but `drawn to a larger Scale and Showing the armature driving mechanism as arranged for director inelastic drive;

Fig. 4 is a cross-Sectional view taken on the line 4 4 of Fig. l but drawn to a larger scale to clearly show the armature driving mechanism; and

Fig. 5 is a cross-sectional view, taken on the line 5-5 of Fig. 1 but drawn vto a larger 'IIS scale, illustrating the armature return spring and the means for preventingk it from opposingr the armature in the initial stage of its flight away from its poles.

The present invention, being primarily directed Ato improvements in the mechanism for loperating the armature, is'largely independent of the particular details ofV construction ofthe magneto proper. The magneto shown is illustrative of a general type and is but, one example of many and various magnetos of this general type with which the invention may be used.

The magneto, illustrated herein, includes al frame A of non-magnetic materia-l, supported from and above a baie B by supportingslegs L. Clamped to frame Aby screws 6 and a bar 7 of non-magnetic material are a pair of laminated soft iron cores 8 which extend vertically upward in spaced parallel relation and, near their'upper ends, are recessed to receive a bank of permanent magnets 9 by whichjthejcores are magnetically connected at their upper ends.' A crossibar 10, of non-magnetic material, serves to tie the cores together.

r`Mounted on the cores 8 and located betweenv this bar and'frame A are primary coils 11. Encompassing each coil 1l lis a secondary coil 12. The coils 12 constitute the vgenerating winding of the magneto and may be connected in 'any suitable and usual manner (not shown). The coils 11 are suitably connected, as for example in series, as by a wire 13 and one .terminal of the primary winding, comprised'by the connected `coils y11, is connected tothe frame of the machine, as by a. wire 14. The other terminal of the primary winding is connected as by a wire 15, to a fixed but adjustableV f breaker point16, mounted in the upper end ofga'tubular metallic casing 17 and insulated therefrom. vCasing 17 is fixed in the bar 7 in vertically upstanding relationand serves as va guide for a plunger 18, which carries the movable breaker point 19 of the interrupter mechanism. Plunger 18 has a ver- I tically depending stem 20.

The armature 2l ismade up of soft iron laminations which are clamped together by screws "22. Each screw 22v passes freely through a spacing sleeve 23 andv one arm 'f of a split pie'ce'24 and is threaded into the other arm thereof. The split piecesJ 24 arel clamped by screws'22 to a shaft-25' which is mounted'to turn inbearings in frame A. The screws 22 also serve to clamp to armature 21 a plate having` a horizontally disposed ledge 26 through which the breaker point'st'em`20 freely passes. TheV armature 21,1 when positionedfas shown in Fig. 5, contacts withfand finagnetically connects the lower ends of cores ,8. It is adapted to be movedl away from its poles by suitable mechanism to be later described and by its downt and electromotive force'is generated in the,

secondary coils 12.

lThe magneto, as thus far described, is of well known construction and. for the purposes of this invention, merely serves as a representative example of one magneto of av given type with which the vinvention maybe used. The details of construction, as described, aretherefore not important and may be varied in many and various ways.

According to the present invention the usual'armatnre return spring' has been eliminated and the location of theusual breaker point spring has beenchanged so as to be reffective to also move the armaturcin the initial stage of'its return flight. Ordinarily the breaker point rpring is, located between the base of plunger 18and the upper face vof ledge 26 so that it is not inany sense effective to move the armature ktoward its poles,-ha`ving on the'contrary the directly oppositeeffect. As shown in Fig. 5, I have located the breaker point spring, designated 28, between the flange27 and base B, orany other suitable and underlying abutment. By so doing, the spring 28 is enabled to Supply the lifting force to move armature 21, b v means of the interengagement of flange 27 an'd'ledge ,26, in the initial stage of its return flight,-carrying it sniciently closeito the magnetic poles, afforded by the lower endsV ofV cores 8, so that the armature can be drawn into its upper position by the force y of magnetic attraction. The spring 28 lifts vthe armature until the breaker points 16 armature.v during that part of its downward Hight which isreffective in the production of a spark from the magneto, is unopposed by the action of spring 28. After thev breaker points open andas thearmaturecontinues to move downwardly, the spring 28 isy coin-` pressed and acts in the usual way to cushion and yieldingly arrest the armature. Y y

The armature ,may be moved away from its poles by. any .suitable `mechanism and various mechanisms will readily occur to hose skilled in the art. The important' considerat-ion `is thatl the driving mechanism,

ywhatsoever its character may.be,is unopposed at a time when it is intended to move the armature as quickly as possible-to produce afspark. Naturally, the invention is of ygreatest importance where a spring drive .is fixed, has also fixed thereto al lever 30, ,to the free end of which a stud 3l is fixed.

Slidableon shaft 25 is a sleeve 32 (Fig. 3) having a clutch groove 33 to receive a shifter aini 34 F ig. which may be manually moved by a lever 35 from the position shown in Fig. 2 to that shown in Fig. er vice yversa. lviountedside by side and for free Vturning movement on sleeve 32 are two arms 36 and 37 (Fig. The upper arm 36 (Figs. 3 and 4) carries a'right-angularly turned lug 38 -wliich underlies thelower arm 37 and the latter carries a similar lug 39 (Fig. 4') which overlies the upper arm. These lugs 3S and 39.7liinit the degree to whichv arms 36 and 37 may be swung apart anda drive spring interposed between the free ends of the arms tends to move fthe arms apart to the extent permitted .by lugs 38 and 39. The spring 40 encompasses two lugs '4l (.Fig.4)i,'one on each of the levers 3.6 and 3T, andthese lugs, which are normally held separated by spring 40, are adapted tobe engaged by moving the levers toward oneianother. The upper rlever 36 has a lug 42 which fis engagediby aroll 43`mountedon a crank pin 44, carried bythe drive shaft 45 which is'rotatably mounted in frame A near one end thereof. Thus, leverv 36 may be periodically depressed. The movement of lever 36 may be directly communicated to lever 30 by shifting sleeve 32 so that the lug 42 ovcrlies the lever 30 as shown in Fig. 3. In this case an inelastic transmission of force is transmitted from the drive shaft 45 to the armature.

When sleeve 32 is shifted into the position shown in Fig. 2, the lug 42 no longer overlies lever 30. The lever 37however, has a lug 46 which rests on the stud 3l carried by lever 30. Consequently, a depression of lever 36 will compress spring 40 against lever 37 which is held stationary by stud 3l. The stressing of spring 40 continues until the lugs 41 are brought into engagementA but even then spring 40 has not .been stressed sufficiently to enable it to move armature 21 away from its poles. The magnetic .hold en armature 2l must first be broken and this is effected by an inelastic t 'ansmission kfrom the drive shaft 45 throughlever 36, the engaged lugs 4l, lever 37, stud 3l, lever-'30, and shaft 25 to the armature. Immediately after the armature has been thus pried off its poles and as soon as'even the'slightest air gap is created between the same, the force of magnetic attraction on the armature is diminished to such an extent that the stressed drive spring '40 is enabled to inove the armature. In the downward movement of the armature the opposition due to magnetic attraction rapidly diminishes and the expanding spring is thus effective to move-the armature at accelerated speed and ataspeed entirely independent of engine'speed. At the optimum point in the downward flight of `the armature the breaker points open and a spark manner.

' It will, therefore, be appreciated that it is important to reduce, so far as possible, the forces which oppose the downward movement of the .armature up to the time when such movement is effective in the production of an E. M. VF. from the magneto. By this invention the armature return spring is posiproduced in the .usual and known .tively prevented` from opposing the armature movement at the state-d time and the only opposition from the spring comes in the final stage of the downward Hight ofthe arinatuie after the spark has been produced. Accordingly. such opposition does not matter.

It-is not essential for all purposes that the return spring be the saine spring which-tends to close the breaker points.` The same result can readily be `effected by another spring leaving Vthe breaker lpoints vto be operated in exactly the .saine way as heretofore. The invention, therefore, in its broadest aspect, is independent of the interrupter mechanism. However, it is desirable `and preferred to utilize .the breaker point spring as an armature return spring and to utilize theV breaker points as stops to limit kthe action of the springen 4the armature. There is, by so doing, .the advantage of reduction lin the number of parts by making one part perform two functions. There is also the advantage of securing perfect coordination in a very simple way for the breaker points themselves prevent opposition of the ret-urn spring on the armature until they open. The desired result is thus certain to occur at the proper time without providing any special timing means.

The invention has been disclosed herein, in an embodiment at present preferred, for illustrative purposes but the scope of the invention is defined by the appended claims rather than by the foregoing description.

i away from said pole pieces.

LII

'2. Ina magneto, ofthe type wherein an armature moves into and' out of contact with magnetic pole pieces to which it is normally held by magnetic attraction, mechanism for movingA ther armature Vaway from its pole pieces including means e'iective by a non- 'elastictra'nsmissi'on to break the' magnetic hold on the armature and previously stresscd elastic means'to move the armature after such 'hold has been broken,A elastic means tending to move the armature toward'its.

pole pieces, and means for limiting the action ot the last named means on'the armature so that it moves the armature 'only part way toward said pole pieces butsutliciently close thereto to enable the armature to lbe drawn into .Contact with its pole pieces by magnetic attraction. l

i 3.'In a magneto, of the type wherein an armature is moved Ytoward andiaway from magnetic pole pieces@ driving lmeansy for moving the armature away from said pole pieces, anfinterrupter mechanism associated with themagneto and'oomprising cooperating and relatively movable breaker points, and elastic'means for thev combined'purposes of Vengaging said breaker points and of moving the armature toward its pole'pieees and suticiently K- close thereto to enable the remainder of the return movementV of the armature to be completed by magnetic at'- traction. f

4. 'In a magneto, of the type wherein an armature is moved toward and 'away `from magnetic pole pieces to vary the reluctance ofV 'a magnetic'circuit and -a generating and a choke winding is associated with said magnetic circuit, the choke winding being arranged in an electric circuit which can be openedv and closed, cooperatingand relatively movable breaker points for opening and-clos ing said electrical' circuit, driving lmeans for .moving the armature' away from'its pole pieces', means for separating said breaker points Vat an intermediate pointin the iight ot thearmature away from its pole pieces and elast-ic means' tending to engage sait breakerpoints and tending also to move said prising cooperating and relatively movable breaker points, driving means for moving the armature awayfroin its pole pieces, an abutinent'movable with the armature vand an abutment movable with one of the breaker points, said abutment engaging at an intermediate po'intin the lflight of the armature away from its pole pieces to separate 'said breaker points,` and elastic means tending to hold said breaker points. in engagement and acting 'also to move the armature'toward its pole pieces through the intermediary of said breaker point abutment.v

'6. In amagneto, of the type whereinan armature is movedrinto and out otcontact with magnetic poles, driving means for moving the armature away from its poles, an abutment movable with the arm`ature,'a sec` ond abutment,l resilient means acting 'on the second abutment and `tendingto engage it with the first abutment for the purpose lof moving the armature ,toward its poles, and a stop to limit the movement of the second abutment by said resilient means fand arranged so that the armature is moved only part way toward itspoles by said resilient means but suliiciently close to said poles so that the armature may be drawn thereto by magnetic attraction. K i

signature. t

f l' TERE-ENCE G.KLO UIS.

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