US1549953A - Ignition magneto - Google Patents

Description

- Aug; 185, 1925.

' F. w. ANDREW IGNITION MAGNETO 6 Sheets-Sheet 4 Filed Oct. 3, 1921 lie/6MM 7f3/Waffen Aug. la, i925..

F. W. ANDREW IGNITION MAGNETO Filed (9ct. 3, 1.921 6 Smau-Sheet 5A Aug. 1s, 1.925. y, 1,549,953

, F. W. ANDREW IGNITION MAGNET Filed oct. 5;1921 e sheets-sheet 6 gnou/woz Ww/Mk #h/:draw 35% @Ho/mam Patented Aug. 18, 1925.`

vUNITED STATES PATENT OFFICE.

FREDERICK WANDREW, OR BROOKLYN, NEW Yonx, .issIGNOR To EISENMANN MAG- NETO' coRrORA'rroN, OE BROOKLYN, NEW YORK, A CORPORATION or NEW YORK.

IGNITION MAGNETO.

'Application led ctober 3, 1921. Serial N0.' 5(l4934.

To all lwhom t may concern; Be it known :that I, FREDERICK DREW, a citizen of the United States,y and a resident of the city of l New York, borough of Brooklyn, county of` Kings, and 'State of `New York, have invented certain new and 'useful Improvements in Ignition -ltiagnetos, of which the following is a specification.'

'My invention relates to that type of magnetos which are adapted to produce electric sparks suiiicient to ignite the explosive mixture in thecylinder or cylinders of internal combustion engines, more commonly called gas engines. The magneto of my invention .differs in severalmaterial respects from the magnetos heretofore constructed and possesses advantages not inherent in-prio-r devices.

One of the principal objects of my invention is to construct a magneto powerful enough to iire large gas enginesand'yet sufficiently small and compact to permit of installation in places where but little space is available. o l I .Another general obJect of my invention 1s to provide a magneto which can be manufactured at lessfc'ost than prior machines of this class, without impairing its durability line of Fig.. 1;

`and efficiency of operation. Furthermore, a magneto constructed according tomy'invention is easily changed from a one-cylinder to a multi-cylinder machine, as will later apear; f Y

p The above land other objects and advan tages of my. invention will become apparent from a detailed description of `the embodiment illustrated/in .the accompanying drawings, in which/- I Fig. l'is ailongitudinal cross-section'of an ignition. magneto constructed in accordance with my invention; v

Fig.'2' is a plan view approximately on line-2-'2 of Fig. 1;

Fig. 3. isxa transverse cross-section at `the distributor end of thel magneto', approximately on line o3--3 'of- Figb;

Fig. 4 'is a transverse' cross-section` of'the 'drive end' ofthe magnto, approximately On 'Fig 5 is a. sectional planview taken approximately on line 5-5 of Fig. 1;'

Fig. 6 is a perspective View of the nonmagnetic unit casting which forms the supporting framework ofthe magneto, this figure being on a slightly reduced scale as compared with the other gures; Fig. 7 is a plan view of the casting shown in Fig. 6;

Fig. 8 shows a transverse cross-section on line'S-S of Fig. 7

Fig 8*? is a fragmentary enlarged view of my new short-circuiting device;

Fig. 8b is a fragmentary view .of a modi# lied form of short-circuiting device;

Fig'. 9 shows the magneto in .erid view lookingv from right to left of Fig. 1 and with the distributor block removed;

Fig. 10 is a detached perspective view of Figrll is a detached' erspective view of" the cam which controlsgt e movable arm of the circuit breaker;

Fig. l2 is a fragmentary perspective View of the circuit., breaker;

Fig. 13 is a fragmentar perspective View showing how the `movable breaker arm is grounded through a flexible conducting strip;

Fig. 14 is a fragmentary perspective View showing my new primaryl brush construction, this view being enlarged for the Sake of clearness;

Fig. 15 shows my new method of fastening the cable or conductor inthe distributor block, a portion f the ligure being lin crosssection;

Figl is an inside faceview of the dis# tributor block shown in'Fig. 15;

Fig. 17y isa-wiring diagram showing how the magnetois connected in, circuit'with the spark plug of a gas engine;

Fig. 18 shows a longitudinal cross-section of the distributing end Of a two-cylinder `magneto changed from vthe Onecylinder magneto shown in Fig. 1;

Fig.- 19 is an end view ofthe magneto shown in Fig. 18, with the 'distributor block veo removed and with the distributor disk shown yin section at the line 19-19 of Fig. 18;

Fi is a detached perspective view of the circuit breaker cam used in the machine of Fig. 18; Y i.

Fig. 21 is an inside face/view of the twocylinder distributor block embodied in' the magneto of 18;

Fig. 22 is a crosssection approximately on line 22--22 of Fig. 21;

Fig. 23 is a face View of the distributor disk embodied in Fig. 18;

Fig. 24 is a detached perspective view of the metallic contact member embedded in the distributor disk of Fig. 23; and

Fig. is an enlarged View of the pointed screw shown. in Figs. 15 and 22 for fastening the cable or conductor in the-distijibutor block.

As one of the lnovel features of my invention resides in the construction by which a one-cylinder magneto y'can readily and quickly be changed 'into a multi-cylinder .niagneto, and vice versa, I have shown a one-cylinder magneto in Figs. 1 to 5 and a two-cylinder magneto in Figs. 18 to 24, inclusive. I will first describe the single cylinder magneto and then explain how the same can be easily changed into a two-cylinder magneto by the mere substitution 'of a few parts.

The main supporting framework of my new magneto preferably consists of a single casting of non-magnetic material, such as aluminum. The general form and outline of this non-magneticcasting, indicated as a whole by C, is best shown in Figs. 6, 7 and 8, from which it will be seen that the casting comprises, roughly speaking, a base 1, a pair of end. plates. or . pieces 2 and 3, and a top 4., Between the end plates the casting has rectangular openings 5 and 6, in which are secured the iron pole pieces 7 and 8, as b est shown in Fig. 8. 'The end piece 3 has a circular opening 9 sufficiently large to permit insertion of the armature as a whole, as may be seen from Fig. 5. 4The base 1 of the casting is formed with la cylindrical recess 10- and the top 4 has a similar recessv or cutaway portion 11 for the purpose of accommodating the cylindrical armature, as will be understood. The end late 2 has a central opening 12, through w ich projects the drive end of the armature shaft, as will be explained later, and is further provided ith an inwardly extending cylindrical flange or shoulder 13, as best shown in Fig. 6. Between the end pieces 2 and 3 the casting i's formed with a recess 14. to receive the legs of the permanent magnet or magnets M. The other structural details of the main casting or framework C will be referred to as `the description of the drawings progresses.

Between the pole pieces 7 and 8 is mount- 1.- The armature A has an end plate or odisk 15 at the drive end and an end plate or disk 16 at the other end, these plates being of non-magnetic material. These end plates, which are preferably of bronze or brass, are rigidly secured tothe iron poles 17 of 'the armature core in' any suitable way.

The end disk '15 has a hub 18 to which is secured the'shaft 19 adapted to be driven from the engine either direct or through a suitablel oscillator or iinpulsestarter. This willbe clear to those who 'are ac uainted with apparatus of this kind. The s 'aft 19, which may be `called the drive shaft, is rotatably supported in the casting C, through a suitable bearing which, in the present instance, comprises an inner ring 20, an outer ring 21 and ball bearings 22. The ring 21 jis secured in the recess formed by the cylindrical flange or'shoulder 13 of the casting C. The bearing 20-21-22 is such as to permit the ready withdrawal and insertion of thev armature 'in the magneto housing. To the outer face of the end disk 15 is secured a low-tension collector ring, indicated 'as a wholeby L in Fig. 10. This ring, which is preferably made from a cut-punching of a suitable conducting material, consists of a disk or bodyportion 23 and a cylindrical contact flange2f1. The collector ring L is secured'to the end plate or disk 15 of the armature by suitable fastening devices, suoli as the screws 25 and 26, as shown in Fig. 5, and is electrically insulated from the disk 15 and the grounded .framework of the magneto. In the present instance, this insulation is accomplished as follows, reference being had to Figs. 1 and 5: A ring 27 o f suitable insulating material is interposed between the collector ring L and 'the end disk 15 of the armature. Preferably, the ring or washer 27 is attached to the ring L by rivets 28 or other wise, these rivets passing openings 29 (see Fig. 10) in the disk 23 of the collector ring L. The screw 25 passes through'av' opening 30 (see Fig. 10) in the collector ring L yand is insulated from this ring by an inin Fig. 5. Thescrew 26 serves as a connecting terminal for the conductor 34, which is connected to the armature coils l) and S, as indicated in the wiring diagram of Fig. 17. The end of the conductor 34 is rigidly clamped to the screw 26 in any suitable Way, as by aA nut /35 or otherwise. As seen fron| Fig. 17, the conductor' 34 forms a common lead from the primary and secondary coils. The other terminal of the primary or low-tension coil P is connected to the metal of the armature and is therefore grounded, as it is technically termed. This grounding of the coil P is diagrammatically indicated at g in Fig. 17. The end disk 15 of the armature is also grounded as diagrammatically indicated at g in Fig. 17.

It will be evident t-hat the mounting of the low-tension collector ring L on the end disk 15 of the armature saves end space on the magneto, thereby contributing to the compactness of the machine. Also, a collector ring made from a cut punching is materially cheaper than the cast or molded'sliprings used in prior machines and which were mounted directly on the armature shaft, thereby adding to the length of the magneto.

The opposite end of the armature--the end which I may call the distributor end--is supported in the end plate 36 secured tothe casting C by screws 37 or otherwise. The end plate S6-is sho-Wn in cross-section in Figs. 1, 5 and 18; the end vviews of Figs. 9

and 19 show the plate 36 in elevation. Theplate 36 is secured against the end piece 3 of the casting C, as best indicated in Fig. 6, the screws or fastening device 37 passing into holes 38 in the end piece 3. A suitable bearing, indie-ated as a whole by B, rotatably supports the distributor end of the armature in the end plate 36. The bearing B is preferably similar to the bearing 26-21-22 which suppo-rts the drive end ofthe rotary armature shaft. In the hub 16 of the end disk 16 is mounted a shaft 39 of suitable insulating material, as best shown in Figs. 1 and 18. The inner end of the insulated shaft 39 has a disk-like enlargement 40 which is firmly seatedl in a correspondingly shaped recess 41 in the end member 16 of the armat-ure. Through an axial opening in the shaft 39 extends the leading-'out Wire 42 of the high-tension secondary Icoil S.'

This connection is shown in Figs. 1 and 17 and is diagrammatically indicated inl Fig.

7.- .The wire 42y terminates in o-r contacts with a but-ton or bushing 44, which is sub-- stantially Hush with the outer end of shaft Speaking in a practical Way, it may' be said that the armature shaft of my new magneto consists of the driving end 19 and the insulated distributor end 39, these ends being arranged in axial alignment and constituting in effect a single rotary shaft. The complete embedding of the high-tension conductor 42 between the secondary coil and the button 44 in an insulated portion of the r0- tary, armature shaft removes the danger to which exposed conductors are usually subject in devices of this kind. Furthermore, since the contact button 44 is concentric with the axis of the rotation of the armature, it

is, in fact, practically a stationary contact and requires simpler mechanism for collecting the current therefrom than in the case of collector ring contacts. Attention is called to the fact that the insulating shaft 39 project-s axially a consideral'ile distance beyond the hub 16 of end disk .16. Consequently, the brush (to be described later) that engages the high-tension contact 44 at the outer end of shaft 39 is separated from the nearest point of end disk 16 by considerafble surface insulation. This arrangement thus insures a safe insulation of the high-tension contact brush an important feature in high-tension ignition magnetos, as any ignition engineer will understand. The armature as above described ,may be removed as a unit from the cast-ing or frame C after the end plate 36 has been taken ofi'. It will be noticed in Fig. 9 that the outer end of the shaft 39 is formed with a straight shoulder 45 by cutting away a segment of the material. The purpose of the shoulder 45 Will be apparent later when I explain how a one-cylinde-r magneto may be readily changed into a multi-cylinder magneto, or vlce versa.

pI- will now describe the primary brush construction, by means of which the lowtension currentis collected from the rotary` armature. In the top 4 o-f the casting G 1s mounted a pair of brushes 46 and 47, made of a good conducting material possessing inherent lubricating qualities and a` low contact drop-such as copper-graphite. The angle at which these brushes are preferably mounted is such that the center line or axis of each brush passes through lthe axis of the armature shaft,'or.as nearlyso as mechanical conditions permit. This angular arrangement of the brushes is clearly seen from Fig. 4. The brush 46 is arranged to bear upon the flange 24 of the collector-ring L, as illust-rated in Figs. 4 and 1.4, and is completely insulated from the framework of the machine by an insulating bushing 48 lining an opening 49 in the -to-p 4 o-ffthe casting C (see Figs. 7 and 14). The/insulating bushing 48 has a flange 50,ajdapted into the-recess '51 which ,suo-unds'v the -top A of the opening 49, as best shown in Fig. 7.

The 'brush 47 passes ,through an opening 52 in the top 4. of lthe casting C (see Fig. 7) and is arranged in alignment .with the grounded disk 15, which is one of the end members of the armature, as previously deto fit llf) ' Cil scribed. The brush 47 is not insulated from the framework of the machine. The brushes 46 and 47 are pressed against their respective rotary members L and 15 by a single to-r# sional spring 53 coiled about a. pin 54 which may conveniently be in the form of av screw fastened into a projection 55 on the -top 4 of the casting C, as best shown in Figs. 1 and 14, The hooked or looped end 56 of the spring 53 presses down on the brush 46, while the other looped end 57 of the spring bears do'wn on t-he brush 47, as clearly shown in Fig. 14. An insulating washer or bushing 58 is interposed" between the brush 46 and the end 56 of the torsional spring 53. The washer 58 is4 preferably provided with a collar 59 around which the end 56 of the spring is coiled. This insures the electrical insulation of the brush46 and at the same time prevents displacement of the spring end 56. The insulating bushing 58-59 may be formed as an integral part from fiber or other suitable insulating material. The other end 57 of the spring 53 is looped around the conductor 60, which is connected to the brush 47. As the brush 47 is grounded, there is no necessity for interposin any insulation between the brush and t e spring. The normal set of the coiled. torsional spring 53 is such that it holds the brushes yieldably against the rotary members L and 15 respectively.

Through the insulating bushing 58--59 onA top of the brush 46 extends aconduct-or 61, the inner end of which is secured to the brush in any well known manner. The other end of the conductor 61 is fastened to a metal clip 62 at the point 63, as shown in Figs. 2 and 14. The clip 62 is secured on the projection 64 on the top 4 of the frame or castin C by means of ascrew 65 or otherwise. T e screw 65 passes into a hole 66 in the projections 64, as'sho-wn in Figs. 6 and 7. Theclip 62 is insulated by means of apair of insulating washers 67 and 68 bet-Ween which the clip is clamped. This is illustrated in Figs. 4 and 14.

The conductor 60, which leads from the brush 47, is at its other Aend connected to a metal clip 69 secured to the top of the casting by a screw 70, o-r otherwise. The screw- 70 passes into an opening 71`in the projection 55 on top of the casting C, as shown in Figs. 1, 6jand 7.

The top 4 of the casting C isv provided with a recess or chamber 72 (see Figs. 6

' and 7) for receiving a condenser K (see Fig. 1) ofv suitable construction. I prefer to use a paper condenser, because of its lower cost than the mica condensers, and I can safely use a paper condenser for reasons which I will now state. There are special advantages in placing the condenser on top of the magneto frame. In prior magneto constructions' using a rotating winding, the

condenser has ordinarily .been mounted on the rotating element of the machine. It is a matter of common knowledge and experience that the rotating element of a magneto develops considerable heat during operation and on that account it has heretofore been necessary -to use a condenser with a dielectric of mica which is not easily affected by heat. Condensers of this type are considerably more expensive thanthe so-called paper condensers in which sheets o-f paper are used to separate the tinfoil, the whole being impregnated with paran or a similar substance. If avpaper condenser were mounted on the rotating element of a magneto, the heatl developed in ope-ration would melt or soften the paraffin, which would then be thrown out by centrifugal force, with the result that the action of the condenser would be destroyed or impaired. Now, this objection is entirely overcome in my construction by mounting the condenser K Within the chamber 72 on top of the casting. As the condenser is separated from the rotating armature by the wall 4 of the casting, 1t is out of the heat zo-ne caused by the operation of the machine-at least, out of the most intense heat. But even if, for any reason the temperature of the condenser should mount so high as to soften the paraiiintthat material could not escape from the chamber and the condense-r would continue to function. By being thus able to use a paper condenser in absolute safety, I bring down the `manu fact-uring cost of. the machine.

The condenser chamber 72 is covered with a plate 73, which is held inA place by the screw 70 and additional screws 74 and 75 ASisee Fig. 2), or by any other suitable means.

s shown in Fig. 2, the plate 73 does not entirely cover the chamberv72 -but leaves a space suiiicient to Abring out the insulated condenser terminal 76. The plate73 has the advantage that it keeps the vcondenser compressed, thus insuring a practically,` constant capacity. To the termina-l 7 6 are connected the conductors 77 and 78 (see Fig 2), while the other terminal of the' condenser is groundedl under screw 74, these condenser connections being Well understood by those familiar with ignitiop apparatus. The conductor 77 is electrically connected at 7 9 to the insulated clip 62, to which the brush 64l is connected, as previously described. The conductor 78 is suitably connected -to the fixed terminal-80 at the point 81. The terminal 80, which is.a block of good conducting material, has' an opening or slot 80' (see Figs. 1 and 12) for receiving a rigid insulating strip 82. The terminal 80 is secured at right anglesto the 'insulating cient rigidity and strength, such als bakep osts 84 by screws 85 or otherwise. lThe grounding the breaker arm 89.

posts 84 are preferably yan integral part of thev top 4c of the casting, as best shown in Fig. 6. The fastening devices'" 85 enter holes 86 in the posts 84. It will be seen that I have provided a very simple insulated mounting Jfor the terminal 80, which is easily put in place. and removed when required. The terminal 80 carries an adjustable Acontact screw 87, which co-operates with a movable contact 88 to form the circuit breaker' of the magneto for controlling the primary circuit, as will be understood by those skilled in the art. The movable contact 88 is carried at the outer end of the breaker arm 89, pivoted to the casting by means of a screw or pin 90, which enters an opening 91 in the top of the casting (see Fig. 6). vThe Contact 88 is normally pressed against the iXed Contact 87 by a spring 92 coiled vabout the pin or screw 90, as shown in Figs. 2 and 12. The iixed contactp87 is insulated and the movable contact 88 is grounded. As the movable pivot of the breaker arm 89 acts like a high resistance contact, and as it is important in any hightension magneto to keep down the resistance of the primary circuit, I provide a flexible strip 9301: good conducting material for As best shownin Figs.. 2 and 13, the strip 93 is at one end removably secured to the top( 4: of the casting by the screw 75, and at'the other end is suitably connected to a lateral extension 94 on the breaker arm 89. Preferably the connection between the breaker arm 89 and strip 93 is permanent, as a riveted or soldered joint. The strip 93, be-

y -ing easily flexible, does not interfere wvith the movements of the 'breaker arm. The' screw7 5 clamps the strip 93 firmly between the to 'of the casting and the lcover plate 73. T e conductor 93 thus provides a xed circuit connection of lowresistance for the movable contact 88. The strip 93, which is I* -very thin, is bent substantially at right angles to provide an arm of real'. effective length in a small space, andt e connecting clip 93. isl bent'at right' angles to the strip, to provide a flexible' hinge for the entire strip during the operation of the breaker arm 89. In this way thestrains of operation, instead of being localized, are dis.

tributed throughout the strip, thereby considerably prolonging its life.

The breaker arm 89 is formed with a 'right-angled extension 95, which carries at its free end a block 96 of suitable wearing.

material, such as 4fiber. p The block 96 is in vertical alignment with an actuating cam mounted on theend member 1 6 ofthe arinatu're The form of this cam is best shown n Fig.'11, where it is indicated as a whole R. l It will be seen that the cam R condrical flange 99. The ends oifthe flange 99 are bevelled to form cam surfaces 100 and 101.- The cam R, like the collector ring L, is preferably made from a cut punching. It will be understood that the form of the cam R shown in Fig. 11 is for a one-cylinder magneto and that the shape of the cam will naturally depend upon the number of cylinders in the engine to which the magneto is connected. The cam R, which is preferably of hard steel, is secured to the end disk 16 ot' the armature by a screw 102, orpotherwise (see Fig. 3). When the camA is in place Ion the disk 16, the liange 99 overlaps the periphery of the-disk, as shown in Figs. 1 and 5. In other words, the cam R forms in eifect a removable section of the disk 16. It will be clear from Fig. 3 that, as long as theblock 96 of the breaker arm 89 en gages the cylindrical flange 99 of the cam R, the contacts 87 and 88 are held apart and the primary circuit of the magneto is open. As the, cam surface 100 passes under the block 96 in the direction of the arrow a in Fig. 3, the contacts are allowed to open inducing a current of sufficiently high volt-v i age in the secondary circuit S to produce a spark at the spark plug F (see Fig. 17). This operation is well understood .and nothing further need be said yabout it.

T o change the magneto from a right-hand A' to a left-hand rotation, or vice versa, it is only necessary to change the position of the cam R on the disk 16. Forthis purpose the disk 16 isprovided with a pair or diametrically opposite screw holes.- 103, one of which is shown in Fig. 3; the other screw hole being covered by the screw 102. The cam vR is readily accessible 'upon removal *of the end plate orcover 36. v y

By mounting the primary brushes 46 and 4:7', the condenser K and the breaker contacts-87 and`89, all on,4 top of the magneto frame C, they arein an easily accessible position and may thus be readily .replaced or inspected when desired. This is an advantage, because itl is well known that these parts are liable to et out of order. To protect the parts re er'red'to against dust and moisture, I provide a cover 104 which fits tightly on top of the casting and is securedin pla'ce by' suitable means, such as 4screws 'A105 or bails., The lower edge of the .CII

- tor is shown in Figs. 1, 15 and 16. This distributor consists of a properly shaped block 107 of insulating material provided with a chamber 108, into which projects a brush or contact 109. This brush is usually a piece of carbonand is mounted in a hollow metal plug 110 embedded in the block 107, as best shown in Fig. 1. A light spring 111 presses the brush 109 against the contact 44 when the block- 107 is in place on the magneto. A cable or conductor 112, encased in suit-able insulation 113, is electrically connected to the metal plug 110. The `cable 112 passes through an opening 114 in the distributor block 107 and thefrayed ends 115 of the wires which constitute the conductor 112 are pushed tight against the metal plug (see Figs. 1 and 15), therebyproducing a firm electrical connection between the collector brush 109 and the cable 112. As diagrammatically indicated in Fig. 17, the cable 112 leads to the insulated terminal of the spark plug F. I provide very simple and eiiicient means for securely fastening the cable in the insulator block, and yet permitting easy removal thereof when necessary. This means com rises a set screw 116 having a pointed en 116 (see Fig. 25)', which enters the insulation 113 surroundingY the high-tenj sion cable 112, as illustrated in Fig. 15. It

will be noticed that the screw 116 ierces the insulation of the cable at an ang e in a direction to oppose aforce tending to pull the cable out ofits socket. It will also be seen that tightening of the screw tends to push the innery end of the cable against the metal plug 110i The screw 116 may be entirely concealed in the opening 117 in the insulator block, as shown in Fig. 15. The

screw '116 is not a current-carrying member,

and'its sole --function is to hold the hightension cable in electrical contact with the distributor brush 109. For this reason the and 16) adapted to fit against a corresponding flange or shoulder 119 on the end plate 36, whereby the insulator block is readily lug 120 and notch 121 thus insure a correct positioning of the distributor block. The distributor block is held in place on the magneto by any suitable means, 'such as a spring armA 122 plvoted on the stud 123 carried by the end plate 36. When the spring arm 122 is in locking position, it engages the block 107 substantially at the center, as sho-wn in Figs. 1, 2 and 5. To release the distributor block it is only necessary to swing the arm 122 into the position shown in Figs. 9 and 19.

In ignition magnetos it is frequently desirable to short-circuit the primary coil in order to stop the ignition. I rovide a short-circuiting device in an easi y accessible position on the cover 104. As best shown in the enlarged vi'e'w of Fig. 8, this device comprises a contact pin 124 projecting from a hollow plug 125, which is rigidly secured tothe cover 104 and insulated therefrom by insulating washers 126 and 127. A nut y128 holds the plug 125 firmly in place on the cover 104. A spring 129 within the plug 125 pushes the pin y124 against the terminal 80.A The plug 125 has a screw-threaded extension 130 on which is mounted a nut 131. If desired, a spring 132 may be placed around the screw 130 to hold the nut firmly in adjusted position. The nut 131 is thus electrically connected withlthe terminal through pin 124, plug 125. and screw 130. As long as the nut 131 is out of contact with the grounded cover 104, the primary circuit is completed through the contacts 87 and 88 of the circuit breaker, as previously explained. However, when the nut 131 is screwed down until the flange or skirt 131 lthereof contacts with the raised shoulder 133 of the cover 104, the primary current is short-circuited through pin 124, nut 131 and the grounded cover 104. In the wiring diagram of Fig. 17 the grounded connection of the nut 131 is diagrammatically indicated at g2.

' If it is desired to control .the short-circuiting device above described from a distant point, it is only necessary to clamp one end of a conductor between the nut 131 and the shoulder 133 in the cover; the other end of the conductor being fastened to a switch mounted on the dashboard or other part of the motor vehicle. The other terminal of the switch would, of course, be grounded. As long as the switch was open, the primary current 'would operate in the usual way, but upon closing the switch the priof contact with the terminal 80. To short-- circuit the magneto windings, it is only necessary topush against the pin 130 until the lower end 124 thereof contacts withthe terminal 80.

A one-cylinderY magneto constructed in accordance with my invention is readily changed into a multi-cylinder magneto by the substitution of a few parts. For the sake of explaining this feature of my .invention, I will assume that a one-cylinder magneto is to be changed into a two-cylinder magneto. This is accomplished by simply removing the cam R and substituting a cam T, asshown in Fig. 20. The cam T is mounted on the end plate 16 of .the armature in the same way as the cam It. The cam T is provided with a pair otscrew holes 134l adapted tore-gister with the screw holes 103 `1in the disk 16, so that, by inserting screws into these aligned openings, the cam T is .rigidly 'mounted on the disk 16 in a predetermined position. For a two-cylinder magneto the'cam T .has two oppositely arranged cam-sections, sincethe circuit must beinterrupted twice during every revolution of the armature. On the projecting end' of the insulated shaft 39 is mounted a distributor disk 136, as shownin Figs. 18,

. 19 and 23. This disk, which is of hard' rub- ,beror other insulating material, has an opening 137 formed with a shoulder 133.

When the disk 136 inserted on the'shaft 39, the shoulder 138 lits againstV thecorrespondlngly arranged shoulder on the shaft 39 (see Fig. 9), -whereby the disk 136 is locked to the shaft 39 so as to rotate therewith, at the same time being free to be relnoved. The ',distributor disk 136 has embedded therein a segmental or arc-shaped contact 139 (see VFigi 424),'lwhich has an eX- tension 140 terminating in a contact button 141. When the distributor disk is in place on the magneto shaft, the button 141 is in V firm contact with the button44 of the magneto shaft, as shown inFig. 18.

In the case of a two-cylinder magneto, the

distributor block 107 is replaced by a di's-- tributor block 142, as shown in Figs. 18, 21.'

and 22. -The general contour of the distributor blok 142 is the same vas that. of the block 107, so that both blocks fit equally welll against the end lplate 36 and are held in y place by the same spring arm 122. The only difference 'between 'the distributor blocks 107 and 142 is that the latter has two collector brushes 143, to which are connected the end 'of cables 144, each cable leading to one of the spark plugs of the engine. The cables 144 are held in electric contact with the brushes 143 in the same manner as the cable 112 in the one-cylinder distributor block 107.-

In'` the operation of the two-cylinder magneto, the segment 139'ofthe rotating distributor disk 136 sweeps over the-brushes 143- in succession, thereby closing the circuit through the spark plugs'at. the proper intervals, as will be understood by those skilled in the art. It will be evident that the shape of the circuit breaker cam and the number of contacts in the distributor will vary with the number `of cylinders in the engine to which the magneto is attached.

From the L foregoing description of an illustrative embodimentof my invention, it v will be seen that I have provided an .ignitionv magneto of small and compact dimensions, particularly as to-length, without iinpairing or diminishing' its'electrical eliiciency. In fact, to give an idea of the vcompactness'of my machine,.the original drawings herewith filed show a full-size magneto which has been successfully operated. The manufacturing cost of such a magneto is cut down -by making-.certain parts from a cut punching (as, for instance, the low-tension collector ring and the circuit breaker cam), 'and by using a paper condenser insteadof the more expensive mica condenser heretofore employed. Those parts which are liable tol require most care and linspectionsuch as the prlmary brushes, the condenser, and

the breaker contactsare mdunted in a i readily accessible position on top of the magneto frame and completely enclosed. so as to be water-proof and dust-proof. Furthermore, as pointed out, a one-cylinder magneto is easily changed into a multi- 4cylinder magneto by the mere substitution of a few parts. r

While I haveherein shown and described a specific construction, I do not intendto be limited to the details set forth. Itis obvious that changes and modifications may be resorted to and yet be within the scope vof my linvention as defined in the appended claims.' Y

What I claim as my inventionis':

1. In',a rotatable armature lfor ignition magnetos, a pair of' end plates between which thev usual Acoils are. supported, aninsulated. collector ring mounted on one of said end plates, said collector ring having a cylindriv12o z cal contact "section and a disk section, :fas

tening devices passing through said disk section into .the adjacent'end-plate, and a circuit-breaker cam mounted on the other end plate.

'2. In an rotatable armature for ignition y inagnetos, a 'pair of end platesbetween which frame or liousiner provided with a top, an

armature rotatahly mounted in said frame and having a pair-of end plates, an insulated collector ring secured to one of said endv plates, said collector ring having a disk section and a cylindrical contact i section extending axially beyond said. disk section,y

fastening devices passing through said disk section into the adjacent end plate, a cam adjustably secured to the other end plate, an insulated brush mounted in the top.- lof said frame and extending through a hole in said top into contact with said cylindrical section, and a circuit-breaker mounted on said top so as to be controlled by said cam.

'4. In an ignition magneto, a non-magnetic frame or housing provided with a top which has an opening near one end thereof, an insulated brush yieldably held in said opening, a circuit-breaker mounted oii said top at the other end thereof, anarmature'j ourn alled in said frame, an insulated collector ring mounted at thel dri-ving end of said armature and engaged by said brush, said collector ring `having a cylindrical contact section and a disk section, fastening devices passing through said disk section into the adjacent end plate, and a cam secured to the other end of said armature to'4 actuateV said circuit-breaker.

'5. In an ignition magneto, a non-magnetic frame having a pair of end plates, o-ne of which is readily removable, an armature hav- .ing a pair of end disks between which the primary and secondary coils are supported, a drive shaft projecting from one of said end disks, an insulated collector ring mount- .ed near said last-mentioned disk, an insulated distributor shaft projecting from the other end disk, means for journalling said shafts in the. end plates of said frame, said distributor shaft being supported in the removable end plate and projecting beyond the same, a contact at the outer end of said distributor shaft, the leading out wire of the secondary coil being inserted llongitudinally in said distributor shaft andV engaging 'said contact, .a distributor block mounted on said removable end plate so as to be readily removable therefrom, and la. brush carried by said block in position to engage said contact. 1 6. In an ignition magneto, a non-magnetic frame havin a pair of end plates, one of which is readily removable, an armature having a pair ofend disks between which the primary and secondary coils are supported, f1

tact at the outer end of said distributor i shaft, the leading-out wire of the secondary coil being inserted longitudinally in said distributor shaft and engaging said contact, in combination with a distributor disk adapted to'be mounted on the projecting end of said distributor shaft so as to rotate therewith,

said distributor disk being readily inserted upon and removable from said distributor shaft, a curreiit-conducting member carried by said distributor disk in position to en gage said Contact when the disk is in place on the distributorshaft, and a distributor block adapted to be -mounted on said removable end plate in operative relation to said distributor disk. I

7 Inan ignition magneto, a non-magnetic frame provided With a pair of end plates, and armature journalled in. said end plates,

one of said end plates being readily removable to permit mounting and dismounting of said armature in and from said frame, said armature having a pair of end disks, a circuitbreaker cam adj ustably mounted on that end disk which is adjacent to the removable end plat-e of said fra-me, whereby theremoval of sai-d last-mentioned end plate renders -said' cam accessible, a collector ring at the other end disk of the armature, and a brush engaging said cylindrical section of the collector iing, saidcylindrical section automatically sliding out of engagement with said brush when the :armature is removed.

8. In an ignition magneto, a nonfmagiietic fra-me provided with a pair of end plates,

an armature journalled in said end plates,r one of said end plates being readily removable to permit mounting and dismounting of said armature in and from said frame, a circuit-breaker cani adjustably and removably mounted on said armature :at that eiid thereof which is adjacent to the removable end plate of said Iframe, whereby the vremoval of said last-mentioned end plate renders said cam accessible, said cam comprising a cylindrical section and a disk section, said cylindrical section being provided with -ai cam surface, and fastening devices passing through said Idisk section into the adjacent end of the armature.

9. In an ignition magneto, ,ian armature construction insertable into and removable from the'magneto frame as a unit, said condrive Ashaft projecting from one of said disks,-

an insulated collector ringl supported adjacent said last-mentioned disk and electrically connected with one end of the armature coils, an insulated shaft projecting from the other end disk, a contact at the outer end ot' said insulated shaft, the leading-out wire of thev secondary-coil being inserted in said insulated shaft and engaging saidcontact, and a circuit-breaker cam mounted on said armature adjacent tosaid other end disk.

10. In an ignition magneto, an armature construction insert-ablel Into andv removable from the magneto frame as a unit, said construction including a pair of end disks between which the usual coils are supported, a drive shaft projecting from one of said disks, an insulated collector ring removably secured to said last-mentioned disk and electrically connected with one'end of the arma- .ture coils, an insulated shaft projecting from the other end disk, a contact at the outer end of said insulated shaft, the leading-out wire of the lSecondary coil being inserted in said insulated shaftyand engaging said contact, and a circuit-breaker cam removably mounted on saidother end disk..

11. In'an ignition magneto, anon-mag? netic frame in which the armature is rotatably mounted, the ,top of said frame being integral with the sides thereof and havino' a recess or chamber, a condenser mounted in said chamber, andl circuit connections for said condenser. l2. In an ignition magneto, a non-magnetic frame in which the armatureis rotatably mounted, the top of said frame being integral with the sides thereof and havin a recess or chamber, acondenser mounte in said chamber and havingan insulated terminal projecting out of said chamber, a. cover for closing the top of said chamber and leaving said terminal exposed, and` conductors connected to said terminal, Jthe other `terminal of the condenser being grounded to said frame. v

13. In an lgmtlon magneto, a nommagnetic frame having a top provided with an opening near one end, a. brush mounted in said opening, a circuit breaker mounted on said top at the other end thereof,'said top being provided with a chamber between said brush and said circuit breaker, a condenser within said chamber, circuit connections from said brush and circuit breaker to said condenser, anda cover removably secured to said top for enclosing the parts.

i mounted thereon.

"t0 said frame.

.brush and circuit breaker' to said condenser,

a cover fitting around said llan'ge for enclosing the parts mounted on said top, and

means for removably securing said cover in place.

15. In an ignition magneto, a non-magnetic frame having a top provided with an opening'l near one end, a brush mounted in said opening a circuit breaker mounted on said top at tie other end thereof, said top being provided with a,4 chamber between said brush and said circuit breaker, a condenser within said chamber, circuit connections from sai'd brush and circuit breaker to said condenser, a cover removably secured to'said top for enclosing the parts mounted thereon, and an -adjustable shortcircuiting device on said cover',.said device having a part extending into contact with said circuit breaker. 16. In ignition magnetos, netic vvframe consisting of a single casting which comprises a base, a top, Sides and a plate at one end, the other end of the casting 'being open to permit insertion` and rea non-magmoval ofthe armature into andvv from the frame, said top having an opening near the first-mentioned end of the casting and, a recess at the other end, a pair of posts on said top near said recess, a rectangular flange formed on said top between said opening and said posts to provide a recess or chamber, and a peripheral flange formed on said top along the two sides and the closed end of the casting, substantially as and for' the purposes specilied 17. In an ignition magneto, a non-magnetic frame in which the armature is mounted, the top of said frame having a recess or chamber, a condenser in said chamber, and a coversecured over saidchamber, said cover holding the condenser compressed to'a predetermined degree, ywhereby said condenser remains. at practically con,- stant capacity.

18. In an ignition-magneto, a non-magnetic frame'- in which the armature is mounted, the top ofv said frame having a recess or chamber, a condenser in said chamber and having a terminal projecting out of said chamber, a cover for said chamber, said cover leaving 'said terminal exposed, and fastening devices for holding said cover in place, whereby said cover holds the' condenser compressed, v one of saidv fastening devices holding the other terminal grounded 19. In an ignition magneto, a4 non-magnetic 'frame in which thearmature 1s mounted, the top of said frame having a recess or chamber, a condenser in said cham- -at the other end thereof, 'said top being proi .vided with a Ychamber between said brush I ber o l l n 1n out of said chamber, said cover leaving one terminal of said condenser projectsaid terminal exposed, a plurality of fasten-l ing devices for holding said cover in place, one of said fastening devices holding the other terminal of the condenser groundedto said frame,` a circuit breaker mounted on tcp oi said frame, said circuit breaker consisting of a stationary terminal and a movable terminal, a pivoted arm carrying said movable terminal, and a flexible conductor connected at one end'to said pivoted arm, the other end of said flexible conductor passes under said cover and is held ground- .ed to the Jframe ing devices.

20. In an ignition magneto, a non-magnetic supporting,frame'liaving a recess or chamber, a paper condenser in said chainbyanothen of said fastenber and a cover secured over said chamber 20 FRE ERICK W. ANDREW.

Certificate .of Correction. l

.It 1s hereby certified'that the name ofthe assignee in Letters Patent No. 1,549,953,

granted August- 18, 1925, upon the application 'of Frederick W. 'Andreu'. of

BrooklymiNeW-l' ork, for an improvement in Written and printed'as Eisenmann Magneto Corporation,

Ignition Magnetos, was erroneously should have been written and printed as E z'semfm/n. Magneto Corporation, as shown by the records of assignments 1n this office; and that the sai'd Letters Patent should be read Withthis correction therein that the same may case' in thev Patent Oflice. l

Signed and sealed this 22d V- [amm] day of September,

confornrto t-he'i'ecord of the KARL FENNING,`

whereas said name

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