US2205561A - Ignition system and magneto therefor - Google Patents

Description

June 25, 1940. HQLTHOUSE I 2,205,561

' IGNITION SYSTEM AND MAGNETO THEREFOR Original Filed Nov. 2. 1936 3 s t -s t 2 2042 Z86 m8 e A 87B? A 252- 282 Z] J20 I Z0 Hair/jg B HoZZho we v35 creases as its speed increases.

The circuits of Figs. 4 to 7 are circuits in- Potent ed June 25, 1940 Harry B. Holthouse, Chicago, Ill.

FOB

Application November 2, 1936, SerialNo. 108,756 Renewed April I, 1939 28 Claims. (Cl. 123-;148) I This application relates to ignition systems and in some of its aspects it relates particularly to magnetos especially suitable for use in ignition systems. The invention is illustrated as em.- 5 bodying a number of modifications both as'to the circuit and as to the magneto.

In nearly all instances the circuits illustrated are designed to produce a spark of high frequency oscillation as well as very high potential, both 10 the high frequency oscillations and high potential being very advantageous in ignition systems:

In one form of the invention which isillustrated in Fig. 1. the system may be operated from a magneto, a direct current generator or a high voltage battery, This system as well as those illustrated in Figs. 2 and 3 produces the ignition.

spark upon closing'of a contact and continues to spark as long as the contact is, closed. The continuing spark is, of course, very advantageous in '20 starting and under any other conditions which make firing at the time of the initial spark un-v certain.

The circuits here disclosed embodysome of the features covered by my prior Patents Nos. I 1-,'ll0,541 and 2,059,237,-and.application 'Serial No. 741,610, with the-last two of which this application is copending. When a magneto is used which is synchronized with the pistons, the circuits of Figs. 1, 2 and 3 so may be used to produce automatic timing, that is, they may be used to cause the spark to occur earlier in the cycle of the engine as the speed of the engine increases, the advance being due to the fact that the voltage of the magneto involving a trip device such as an electrolyticinterrupter. These circuits also include the feature of automatic timing in that the spark oo- 40 curs whenever the current produced by the magneto reaches a predetermined value for which the electrolytic interrupter has been designed. Assoon as the current exceeds this value, the electrolytic interrupter acts in a manner similar 45 to the breaker contacts of a conventional ignition system to produce a high voltage for firing. The voltage may be either a kick (self-induced) voltage, or a voltage induced in a-secondary coil, and this high voltage may be conducted directly 50 to the spark plug or it may actuate a high frequency oscillating circuit which in turn produces a high frequency spark at-the spark plug.

-.All forms of the magneto illustrated are designed to permit an extremely close clearance 55 between the armature and field poles form.

while avoiding the danger of trouble, which might be expected when rotating parts are used having such small clearance, by a bearing arrangement which has a diameter commensurate with the diameter between the poles of therotor so that 5 there will not be any material wear on the bearing. The magneto assembly also includes enough other parts of the ignition system sothat the magneto rotor may act as a-distributor, thus eliminating the separate distributor. In some In instances the rotor includes e'nough parts of the ignitionv system to eliminate numerous connections between the rotor. of the magneto and other parts of; the ignition system.

The objects of the invention are to a large .exis tent apparent from the foregoing brietf discussion of the nature of the invention, but they may be summarized by-stating that one object of the invention is to provide a better ignition system than any' ignition systems heretofore known, except applicant's prior systems. mentioned; and another object of the invention is to provide a bettermagneto than those hereto- Tom known.

Additional objects and advantages will be ap- 26 parent from the following description and from "the drawings, in which:

Figs. 1 to 3 are various forms of ignition circuits involving a mechanical timer which either closes a circuit or narrows a gap to produce firing. 30 Fig. 1 shows a plurality of forms of sources of power,.and a vacuum spark gap which may be'in the other figures as well.

Figs. 4 to? are circuit diagrams showing a plurality of'ignition systems each involving'an electrolytic interrupter.

Fig. 8 is a sectional view showing one form of commutator or timer which maybe used in the circuits of-Figs. 1 to 3.

Fig. Q'iiIustrates a modified form of timer for 40 use in Figs. 1- to 3, at least under certain condi- Figs. 10 and 11 are diagrams illustrating respectively a broad wave-form and a narrow wave- Figs. 12 and 13 are sectional and end views of a rotating field magneto. r' Fig. 14 is a fragmentary sectional view correspending to Fig. 12, but showing a modified form oi magneto. so

shown inFig. 15, showing the magneto in section,

' clarity different aspects of the invention may first- --the section being substantially alongthe line I6'l6 of Fig. 1'7.

Fig. 17 is a sectional view taken substantially along the line I'l-l'! of Fig. 16 partially broken away to show the internal arrangement of the parts.

Fig. 18 is a sectional view taken substantially 'along the line l8--|8 of Fig. 16 to show the arrangement of field magnets.

Fig. 19 is a fragmentary view showing primarily the relationship of the pole faces to the permanent magnets. It is a view taken substantially along the line l9|9 of Fig. 18.

Fig. 20 is a sectional view through another form of magnet0.'

Fig. 21 is a sectional view taken at right angles thereto; approximately alongthe irregular line 2l--2l, successive portions being broken away for clarity; and

Fig. 22 is a diagrammatic representation of another ignition circuit and controller therefor.

Although this invention has been shown in numerous forms. it should be understood that it could also take many additional forms within the broad principles here disclosed. For the sake of a .be considered separately even though they are all same system, in which case switches l6, l1 and I8 would be provided to disconnect two of 'these sources of power while leaving the other one connected. Whichever one of these sourcesof power ll, I2 or I3 is connectedto the ignition system will be connected to a wire 20 which is connected to wire 2| either directly or through a choke coil 23. It will beunderstood that each of the sources of power II, I 2 and I3 is also connected to ground as illustrated.

A condenser 26 is connected a'crossthe source of power (which we ma'y'assume to be the generator 12) by virtue ofpbeing connected between the wire 2| and ground. This condenser will be charged with whatever voltage is produced by generator I2. 'This condenser 26 also forms part of a primary high frequency oscillatingc'ircult which is completed by wire 2|, primary winding 28 of a high frequency transformer, condenser 29,

contact or electrode 30, rotor 3 I, and ground. The

rotor 3| may include raised contacts 32 or segments thereon which at the proper time for ignition engage the brush 30, being driven in sy'nchronism with the motor. If"there is to be no special provision for wave-form timing, the contacts 30 and 32 may comprise ordinary breaker points operated by a cam to close the points when a spark is desired, or they may comprise a commutator such as that illustrated in Fig. 8, in which the contact 30 rides on insulating segment 33 until a spark is desired, at which time'the segment 32, connected to ground through the shaft 34, comes into contact with the contact 30.

the primary oscillating circuit already traced is formed. The high frequency oscillations flowing through primary coil 23 induce a high voltage in a secondary coil 33 which is connected through a distributor 33 to one point of an ignition spark gap 40 (the spark plug of a motor), which is connected to ground as shown. Thus the secondary oscillating circuit includes the secondary coil 38, the spark plug 40, and the condenser '23. The contacts 30 and 32 arc in this circuit too, but they may be disregarded since they are assumed to be closed.

It will be observed that the condenser 23 is a condenser common to both the primary and the secondary oscillating circuits. This is an important feature in obtaining a very hot spark and is covered by one or more of my prior patents previously mentioned. Although it is preferred that this high frequency arrangement be used, it should be understood that other portions of the circuit areindependent of it and maybe used with other arrangements for transmitting a suitable voltage to the spark plug 40.

As long as the contacts 30 and. 32 are in contact or so close that a spark will jump across them,'the sparking at the spark plug 40 will continue, providing that the voltage supplied by the across the gap 40 or the contacts 30 and 32. A

high charge on the condenser 29 when the contacts' 30 and 32 next close might prevent the condenser 26 from discharging therethrough to start the oscillations. It is, therefore, desirable to provide an inductive resistance" or other suitable I impedance connected as shown to serve as a drain for the condenser 29. 'I'he impedance should be high enough so as not to divert much of the oscillating current from the primary coil 23.

The sparking produced at the spark plug 43 is ext emely hot. In fact, if'the source of power sup lies too much power, the points of the spark plug 40 may be melted. It may, therefore, be desirable to insert a choke 23 between the source of. power and the wire 2|, since such a choke coll,

whether having an iron core or an air core, tends to decrease the heat of sustained sparking at the plug 40. This is apparently because the sustained sparking is not actually a continuous spark but rather a series of successive trains of sparks, each train resulting from a discharge of the condenser 26 after which it must beagain charged. The choke coil 23 apparently retards the recharging of condenser 26. ,Whether this theory is sound or not, choke coil 23 doesdecrease the heat of a sustained spark at the plug 40. This apparently does not affect the voltage available for starting the spark since between successive closings of the contacts 30 and 32 there is adequate time for the condenser 26 to become fully charged in spite of the presence of choke 23-.

No mention has been made at this time of the spark gap which maybe connected into the cir- 15 In any event, when the contacts 30 and 32 close, cuit by the switch it since this switch is shown ll open, and that gap is not necessaryto the 'opera-- tion. of the circuit.

The circuit of Fig; 2 is somewhat similar to the-circuit of Fig. 1. Though it is probably very inferior thereto, it isv capable of producing pro-'-- longated'sparking. The magneto I! has been shown, but the possible presence of the other source of power has been indicated by the arrow at the end of wire 20. The condenser has been omitted and the condenser is connected in both the primary and. secondaryosciilating circuitsas well asbeing connected across the source of power. In this circuit the source of power charges the condenser 26, and when the contacts and 32 close, the condenser 2! disa E charges through the primary coil 28 which induces voltages in the secondary coil 28, thus setting -up oscillations in the secondary oscillating,- circuit including the secondary coil 38, the spark plug 40.

ground, and the condenser 28. l

It will be noted that in nearly all of the figures,

the secondary, circuit-has been shown with a niotted line portion. This is merely a simplificacuit is completed and includes besides the condenser 29 the primary winding 28 of a high ,fre-

'quency transformer, the wire 21, contacts 20 and l2 and ground. The-secondary circuit includes f in a circuit through the magneto II, the polarity' l the wave-form cle. The result the condenser 29, the secondary winding 38, the spark plug Ill and ground. It will be observed that, sin'ce the condenser 28 is always includedof which reverses, the impedancef'fl need not be provided for draining the condenser 29. Of course, if it were found that the impedance of. themagneto was too high to drain the condenser 29,.the impedance 42 could be added;

If in Figs. 1 to 3 the contacts 30 and 22 either instead of closing or before closing form a spark 'gapof the proper length for wave-form timing, wave-form timing may be provided when the magneto i3 is used, assuming that the wave-form of the magneto voltage is synchronized with the pistons. As each piston. approaches or reaches the top of its cycle at the .time when explosion is desired, the voltage produced by'the magneto it will reach its maximum. The contacts 30 and 22 may be so adjusted that when the piston is at the top of its stroke, 1. e. when the voltageis at its maximum, this voltage will be just enough at siow'speeds to cause the condenser 26 to discharge across the contacts and 32. As the engine speeds up, however, and the magneto with it, the voltage is increased so that a voltage adequate for discharge is reached earlier in the cyis that the discharge takes place before the piston reaches the top of its stroke, and the ignition is therefore advanced. This automatic wave-form timing is covered by my prior patents above mentioned. With some magnetos might be quite broad as illustrated by Fig. 10 so that. ii the line A-A represents the firing voltage, this voltage will be reached at the smd for whichthe dlfllrams are drawn at the point B which may be advanced by as much as sixty degrees. with atwo-pole magneto this would represent sixty degrees in therevolution of the crank shaft. This would, of'course, be too great an advance and even thirty degrees might be too great an advance ordinarily.

The advance can be controlled to that desired in several ways. One way is by changing the wave-form to that shown in Fig. 11 orto some other suitable wave-form. In Fig. 11 it is seen that the point B at which the wave reaches the firing voltage is advanced only about twenty degrees.

Another manner of speed is by accurately varying the length of the gap; This can probably best be done by a gap including some such rotating element as shown in Fig. 9, in which the contact 30 rides on an insulating rim 46 and the rotor II has a specially shaped] sparking orcontact portion 32'. 'The I shape is such that with the leading end 41 under.

the contact (or electrode) III, the sparking distance .is relatively wide, whereas as the rotor 2| advances, the shape of the portion 22 reduces the length of the sparking gap. It is obvious that, if a voltage sumclent to jump thecontrolling the amount of a advance due to increased voltage upon increased narrow portion of-the gap were reached at say thirty 'degreesadvance, it would not be able to jump the gap because the gap at this time is wider. By carefully shaping the sparking portion 22' any desired advance may be provided for any given wave shape. It shouldalso be ob-' served that the spark portion 22' may be terminated atits' front and 'rear edge by a sharp break so that beyond that portion the surface I! of the rotor will be so far removed from the contact 30 that sparking will be'prevented. even with excessive motor speeds. This will positively limit the ignition-to whatever maximum advance or maximum duration-oi spark may be desired.

v Vacuum timingcorrection I With automatic timing,whether it be of the wave-form type above discussed or of the conventional governor type, there are some situations .spark occurs at exactly the right time, it is likely that are not fully provided for simply on the to follow that ii the throttle is fully opened and other conditions are maintained the same, thetiming will appear to be advanced to the extent that the ignition will take place too quickly and knocking-will result. This may be due to the fact that with the throttlefully' opened more gas is taken into the cylinder and the compression is higher. In the past, attempts have been made to overcome this fault by moving the timer in a spark advancing direction in response to'the vacuum of the intake manifold so that when the throttle-is opened wide, the decreased vae-' uum retards the spark.

According to the present invention, this same eflect of advancing the spark when the vacuum is high, and retarding it when the vacuum is low,

. is accomplished in a more simple manner. If the switch ii in Fig. 1 is left closed and the switch I2 opened, or the controller. 2i disregarded, the

spark will occur whenever the voltage across gap it between a. groimded electrode II and an adiustable electrode II is suflcientto cause a spark to jump the gap'therebetween. In other words, disregarding other considerations, this gap will provide automatic wave-form timing. Accord- I automatic timing is provided (1. e., when a syn ,chronized magneto is used), the controller. ll

The electrode 54 may be adjusted by tuming the screw 58 to give proper timing under these. conditions, and, if the wave-form of the magneto is properfor the particular engine, this timing will be correct for all speeds of the engine.

assuming say an average throttle position at all speeds. If the throttle is opened wide, the tendency toward a quicker ignition is compensated for by a reduction of vacuum in the intake mani- I fold and consequently in the chamber 56 whichincreases the resistance of the gap between electrodes Stand 54, and hence retards the spark. I

It is desirable that a spark gap have a more or less constant change of air and chiefly for this purpose the bleeder valve 80 may be provided so that the suction of the intake manifold will continually draw fresh air intothe chamber 56. The

bleeder valve 60 will also tend to regulate-the.

vacuum in the chamber 58, especially if the conduit 51 should be somewhat constricted. Of course, in place of the bleeder valve ill there may be a fixed small aperture or one or more of the walls of the chamber 56 may be formed of a porous material which will permit air to seep therethrough. Since the wall ii is formed of an insulating material .to insulate the electrode 54 from the metal portions of chamber 58, this wall I could very suitably be made of a'porous material.

One advantageof the provision of a vacuum chamber 56 around the gap 50 is that the. gap may be longer; and hence less subject to fouling. The vacuum will permit the spark to jump over a much longer gap than if the gap were in 'atmospheric pressure. Of course, the rotary gap formed by the electrodes 30 and 32' is hardly subject to fouling, but, if a fixed gap were to be used, it would be very desirable for it to be a vacuum gap. It should be explainedthat in the circuits of Figs. 1, 2 and 3 whenever wave-form and the vacuum chamber 58 may both be used,

normally being connected in parallel. This is especially true if the wave form is of such a desirable shape that compensation for it by shaping the contact 32' is unnecessary. In this case the contact 32' will be of uniform radius except for an enlargement at the end for insuring a spark if one does not occur earlier. During starting, when the voltage of the magneto I3 is extremely low, the vacuum spark gap will be in-- effective and the spark will occur when the primary oscillating circuit is closed by contact of the contact 32 with the contact 30. As the motor electrodes "and 53 and hence advance the timing somewhat.

Of' course, iI-desired, the switch 52 may be .opened after starting, so that during running the timing will be entirely by the spark gaps and 53 to give straight wave-form timing as modified by the vacuum correction. This might be par ticularly advantageous on a long trip when the wave-form timing would be less subject to variation-due to atmospheric conditions if the timing spark gap were included in the vacuum chamber it. However, the rotor II and its electrode or contact 30 could be included within a vacuum chamber.

.Wave-form timing with electrolytic interrupter I In Figs. 4 to "7, I have shown circuits for providing wave-form timing in a somewhat different manner. In these circuits a' device is used for interrupting a short circuit across} a magneto so as to send a. surge of current into the eifective portion of the ignition circuit.

In-its preferred form this trip device is an electrolytic interrupter illustrated diagrammatically in these figures and indicated as a whole by the reference numeral 66. These interrupters are already well known in other connections and include an electrode 61 which is insulated except for a small tip. which tip is submerged in an electrolyte in container 68. which may form the other electrode, This electrolytic interrupter 66 is connected across the magneto I! which, as in Figs. 1 to 3, is synchronized with the pistons. The

operation of such electrolytic interrupter is that they will carry current up to a certain amperage and will then interrupt the current, closing it almost instantaneously, and interrupting it again and again in very rapid succession. These interrupters are very accurate-and the current rate at which they will interrupt may be controlled by the amount of the electrode 6'! which is ex- .posed to the electrolyte. Furthermore, if a plucircuit is completed through the interrupter, a

relatively heavy current will fiow through the coil of the magneto l3. This coil is wound on an iron core and hence a heavy magneticfield is built up. When the interrupter interrupts the current, the collapse of this magnetic field induces a very high voltage. In the circuit'of Fig. 4, this high voltage is applied across the condenser 26, which bears the same relation to the ignition circuit therebeyond as the condenser 26 in Fig. 1. Thus in Fig. 4, the condenser 26 is part of a primary oscillating circuit including primary winding 28 of the high frequency transformer, the condenser 29, a spark gap 10, and

ground. The spark gap 10 may be of any form" y as applied to conventional ignition circuits.

will be understood that when the short circuit of primarywniding' 82 is interrupted byinterrupter aaoacci Of course, a mechanically driven interrupter may be used when wave-form timing is notdesired. Interrupters which could give wave-form timing 'both figures, themasneto- I8 charges the condenser 29, which is permanentlyconnected across the magneto. f course,-in Fig. the charge on condenser 28 is insignificant untilthe interrupter 88 functions, at which time a high kick voltage is impressed on condenser 28. In case .the electrolytic interrupter 88 will not serve as .a spark gap immediately after interruption of the current, a separate spark gap 14 may be provided in parallel therewith, a by-pass condenser 1I being optionally provided as well, though the interrupter 88 may serve as's'ucha condenser. It will'thus be seen that the primary I oscillatingcircultjincludes besides the-condenser so as to function as a spark coil. The magneto this instance the magneto 8| maybe a conventional type of magneto. including botha primary armature winding .82 and. a secondary armature winding 88 wound on the same ,core

' is preferably designed to have the wave-form in the coil a: synchronized wiilh'the pistons; The primary winding 82 is normally short circulted by the electrolytic interrupterj 88, but when the magneto reaches the point on its wave-form'- which yields sufficient current, the interrupter 88 will function to break the circuit of primary winding 82, thus causing a-bre down in the magnetism of its core, whichinduces a high voltage in the secondary winding 83. This induced voltage is cumulative with the normal voltage in the winding 83 due to.rotation of the magneto and the result is therefore a very high voltage.

As shown in Fig. 6, the secondary winding 88 may simply be connected directly to the spark 'The secondary winding 89 of the high frequency transformer is connected in boosting relation ship between secondary winding 83 of the mag-' plug 48 with the'return circuit from the spark 'plug 48 through ground. The-usual distributor would, of course, be included, as in all of the other circuits. 1

Fig. '7 shows a circuit substantially identical with that of Fig. 6, except for the inclusion therewith of a high frequency boosting circuit -disclosed in my prior application, Serial No. 741,610,

88, a high kick voltage will be developed; In

the circuits of. Figs. 4 and 5this kick voltage was used as the main voltage supplied to the ignition system. In Fig. 7 it is utilized for the booster circuit. 'A condenser 88 is connected in a circuit in parallel with the interrupter .68

(unless interrupter 88 has adequate capacity after interruption to serve its purpose), so that it"is charged'by the kick voltage. oscillating circuit is provided for this condenser which includesa primary winding 81 01 a high frequencytrarisformer, anda spark gap 88 which may be provided with a by-pass' condenser 1I.

neto and spark plug 48.

Although these circuits have been illustrated with a .tripdevice comprising an electrolytic in-- terrupter, it should be understood that anyother voltage or current controlled trip device may be used to provide thefeature of wave form timing.

A. primary are magnetic interrupters which operate either with a predetermined current or with a predetermined voltage.

Rotating field magneto Although any form of magneto may be used. subject'to'the requirements of the diiferent circuits already-"mentioned, several forms, of mag-'- netos are illustrated in the drawings which are especially suitable for use in some of these circuits.

The magneto of Figs. 12 and 13 maybe used mail of the circuits except in those of Figs. 8 and 7 1 (and could be used there if another winding were provided). field magneto.- It includes a shaft I88 which I throughout the'central portion is of quite large diameter and revolves in bearing I81. The bear- This magneto is a rotating ing I81 isjof .H-shape in-crcss section to form an annular chamber for the field coil I88. After,

the coil is wound thereon, it is enclosed within the magneto shell I88. This shell- I88 forms part of the stationary armature of the magneto, which is completed by the face members "I,

which are shaped as shown in Fig. 13, and have armaturewlndings I12 on alternate poles I18. The-intervening poles I13 may be left blank for the purpose described in the next paragraph.

It will be observed.v that the coil I88 will'magnetize theshaft I88, making one end thereof always north. and the other always south. At the ends of this shaft are provided field pole pieces I14 having half as many poles as are provided on the'armature face members "I. It .will. be

observed that with the field poles I14 alined with the armature coils I12, a'magnetic circuit will be formed passing through each of the arma-' ture coils I12. However, as the field poles I14 rotate to alinement with theblank polepieces' I18, the magnetic flui'r will be carried almost entirely by said pole pieces I18, with the result that there will'be practically no flu x passing through the coils I12. This change of flux passing through the coils I12 induces a voltage therein according to well known principles. The various coils I12 may therefore'be connected in series and connected in any of. the circuits ofqFigs. 1

to 7. They have been illustrated as connected in at circuit similar to Fig. 1, but with the secondary circuitindependentof contact, 88 and .controller 8I (or .3I').

If this magneto is to be used with wave torm Itiming, it may berotated synchronously with the.

engine'and, of course, it should have theproper number of poles so that one voltage wave will reach its maximum as each' piston reaches the" top ofits compression stroke. 0! course, there .may be intervening waves which may be disregarded for the present. The form of magneto illustrated inFigs. 12 and 13 will serve for a fourcylinder engine, or foran. eight-cylinder engine if the two halves of the voltage'cycles are sumcientl'y alike in wave-form.-

When the magneto makes one revolution for shaft may beused as a distributor shaft, 'as illustrated diagrammaticallyatthe left of Fig.

-12 ,-in which a, distributor arm I8I is carried by the shaft I88 and'e'ngages orcomes into sparkmg relation with the distributor terminals I82, each of which is connected to a spark plug. The

rotor 3| or 8| may also be mounted" on the dis- .each one or two revelations of the engine, its

20. The rotor and brush have been illustrated 1 as structurally similar to one in my Patent No. 2,059,037, though the controller 2| is preferably shaped as shown in Fig. 9, though with additional contacts 32.

One of the main advantages of the form of magneto shown in Fig. 12 is the extremely large bearing which it provides, namely the entire engaging surfaces of shaft I66 and bearing I61. This bearing surface is so large that it will be substantially free from wear. the clearance between the poles I24 and "I may be extremely small without danger of trouble due to slight wear in the bearings. Since the effectiveness of magnetos is largely dependent upon the smallness of the clearance in the magnetic circuit, other factors being the same, this is an extremely important consideration. End plates I64 may be.'provided inside of the laminated pole portion I14 to bear against the bearing I61 to prevent end play. It should be understood, of course, that the bearing I61 is ofa shaft I66 must not come too close to the.armature poles I and-hence the intervening space I86 may be filled with bearing metal. It will be observed that this form of the invention has an even larger bearing surface than that Of Figs. 12 and 13, being just as long, but considerably larger in diameter. Because of this large hearing surface, which substantially eliminates wear,

and because the poles I14 are permanently secured in place and may be machined with extreme accuracy, the magnetic clearance in this form may be extremely small with safety. The rotating portion of the magneto including the shaft I66 and poles I14 may be held in centered position by the magnetic attraction of the poles I14 for the poles I10. Of course, if required, suitable end play bearings may be provided, being preferably of an external nature which will not require removal of the pole pieces I14.

Flywheel magneto Figs. 15 to 19 illustrate a novel form of flywheel magneto and its application to a motor which in this instance is a motor 20I having radially disposed cylinders 202, as seen in Fig. 15. The magneto is carried by the crank shaft 204 of the motor, the rotating portion of the magneto being carried in a flywheel 206 which is non-magnetic, at least in its rim.

The magneto field may desirably comprise permanent magnets 206 radially disposed, as seen 'in Fig. 18, and provided with pole faces 209 which, as seen in Fig. 19, may preferably include clamping legs 2 which squeeze together adjacent poles of two magnets 206. It will be The result is that .cast around the magnets. This base may be secured to the housing 2I6 of crank shaft bearlng 2" in any desired manner, as by the split collar'2l9 which may be tightened by bolt 22!. Such a manner of securing will permit adjustment of the field magnets 206 to provide very small clearances between these magnets and the armature. made in separate members may be cast as a single integral structure, in which case the pole faces 209 may be cast integrally with them.

As seen best in Fig. 16, the armature magnetic circuit may include a heavy iron ring 226 secured to the flywheel 206, cores 220- secured to the ring 226, and pole faces 230 secured to the cores 220. -It will be seen that the magnetic flux from one pole of the field magnet will flow through the core 226, through the ring 226 to adjacent cores 228, and back to opposed poles of the field magnet. As the armature rotates, the polarity in the cores 228 will be reversed and hence these cores and also the ring 226 and the pole faces 230 may be laminated or may be made of some material such as Swedish iron which has relatively high electrical resistance and also relatively high magnetic permeability.

The armature coils 232 are carried by the cores228 and hence have a voltage induced therein due tothe changing magnetic flux in the cores 228. The magneto should be so designed, especially in the number and pqsitions of the poles, that the voltage of the coils will reach its maxi-' mum. as each of the pistons reaches the end of its compression stroke (or slightly later). In the illustrated form there are twice as many poles as there are cylinders.

This magneto may be .used with any of the'circuits of Figs. 1 to 5 (or the circuit of Figs. 6 and '7 if a secondary armature winding is provided).

However, because of features not yet described, it is especially suitable with the circuits of Figs. 1 to 3 when these circuitsinclude the wave-form timing features. It may, therefore, be described as used in the circuit of Fig. 1. The condensers 26 and 29 and a high frequency transformer 234- including coils 28 and 38 may be positioned on the inside of the flywheel, as seen in Fig. 1'7, and secured in any desired manner. For example,

The magnets 208 instead of being they may be set on cradles 236 and secured in place by straps, if desired. In any event, they 'may desirably be completely sealed within the flywheel by some suitable insulating compound 238, such as that known commercially as Bakelite. The condenser 26 will be connected directly across the armature winding comprising the coils 232 and for convenience the flywheel 206 may serve as the ground connection. Primary winding 28 of high frequency transformer. 234 will be connected at one end to the condenser26 and at the other end to the condenser 29. The other side of this condenser 28 will be connected to a sparking e ectrode 20 which may be carried in the manner illustrated in Figs. 16 and 17. In these figures an insulating block 24I is carried by a spring urged arm 242 pivotally' supported on the flywheel and'isspaced from a contact ring 1'13 in any suitable manner, as by spacing legs 244 bearing on rings 245. The rings! and 245 may comprise asingle ring unless it is desired to have the ring 243 of irregular contour. It will usually be preferred that this ring be provided with raised portions. corresponding to the electrodes 32' of Fig. 9. The ring 242 will be grounded to complete the primary oscillating circuit tocondenser 26. l

Suitable arrangements should be made for holding the mm 242 swungto an out of the way I position while the flywheel is being applied to the best in Fig. 16, being insulated from the flywheel by an insulator 249.. The terminal 248 may thus I be used as a distributer. Each spark plug 40 4 will, therefore, be connected by a wire 25! with an arcuately elongated terminal 252 positioned to have the terminal 248 pass in close proximity thereto. Thus, the secondary circuit oscillations will be distributed to the successive spark-plugs in properly timed relationship by the terminal 240. The return circuit from the spark plugs is.

of course,'by way of ground through the ring 243 and contact 30, though it. may be independent of the gap between ring 243 and contact 30 if the .modified circuit of Fig. 12 is used.

The condenser-draining impedance 42' has not been shown in these figures because it is not necessary inasmuch as successive voltages applied to the condenser 29 by the magneto l3 and con,-

denser 126 will be reversed in polarity (assuming at least that condenser 26 discharges into condenser 29 each time) so that any charge remaining on the condenser 29 will be helpful rather than harmful. Likewise the choke 23 has not been'shown'since the magneto cannot give a continuous spark on a' sing e spark plug and so there probably .is no danger of melting the so that the spark between the terminals 248,- and so n will be elongated throughan arc corresponding to,

. 20 degrees;

252 may be observed. The positionof this spark will indicate the timing of the ignition spark. If

the timing is too advanced, the electrode 30 may be unscrewed slightly to elongate the gap between it and the ring 243, thus retarding the timing. It would, of course, be desirable to provide a hole through which access could-be had to the adjustable electrode 30. For this reason the electrode 30 will probably not be positioned in aline-' .ment with armature poles 230, although this position was chosenfor the purpose of simplicity of illustration in Fig. 16. v It should be understood that the terminals 252 the maximum advance in timing desired. With the magneto illustrated having six poles there would be six current surges in each revolution and, since. the wave-form timing ordinarily 'uses only half of each current surge, it follows that the maximum advance timing available is something less than A: of a revolution, perhaps about .This, however; is adequate for most motors unless they run at very high speeds and, of course, if greater advance is desired, a mag-j neto could be designed with a smaller number of poles. J

It should be understood, of course, that the flywheel should be properly balance'dso that its "voltage in slow speed cranking.

rotation not produce-vibration... The condensers 2,6 and 2mm thearm 243 with its assOF- ciated parts-may ordinarily be -so located as toproduce the 'parti'cular wave shape which will .give proper timing. The general principles'of changing the wave shape by shaping. the poles.

are sufficiently well known to enable the skilled ma'gn'etos may be given any shapes necessary to i designers to produce satisfactory wave shapes without'special instructions. However, where the whole wave is very narrow as in magnetos having as many as say six surges a revolution, it will not usually be necessary to give the wave a narthat when the piston reaches dea center it is desirable for the gap to" close to ut ize anyweak row shape, or to provide a changirg gap, except Radial bearing magneto In Figs. 20 and 21 another magneto is illustrated which is quite similar to the flywheel magneto of Figs. to 18 especially in that it incorporates the important feature of having the condensers and transformer rotate-with the coils so thatall external connections except the spark gap and the self contained distributor can be eliminated. In these Figs. 20 and 21 the same reference characters have been used as in Figs. 15 to 18 as far as possible. The shaft 204' may be an enginecrank shaft or a separate shaft geared theretp.- Thepermanent-magnets 208 are secured to the base 2 in any suitable manner and are provided with pole faces 209. The intersticeo between legs of magnets 208 are preferably filled with a-metal of which the base 2l4 is cast. On the front side of this a layer of non-magnetic bearingmetal 26l is provided with its outer suring metal 26L To the bearing plate 262 are secured core laminations 263 which may desirably f be stamped out in'one piece spiders, as seen best at the lower right hand portion'of Fig. 21. The

armature coils 232 are slipped over these spiders,

afterwhich the armature pole faces 230 are secured to the legs of thespider 236. If desired,

-the .coils 232 may fill the radialspace between the cores 263.

The pole faces 230 may be secured by screws 266, which also secure a table 261 of some such suitable insulating'material as Bakelite.. On-

this table are carried the condensers 26 and 29 and the transformer 234. There may also be carried on this table a controller 2' corres1: ondin g to the rotor 3|. In this instance it may be more desirable .to ground the stationary sparking contact 212 than the rotating controller 211. In any-event, the controller 2'" may desirably include a ring 213 having raised portions corresponding to the specially shaped contacts 32'. These raised portions may be shaped to alter -troller suchas' 31 or'31' is used with the illustrated circuits, it will probably be desirable, when practical, to make provision for discharge of the primary circuit on every voltage surge of the generator. This will probably make the provision of the 'drain impedance for'the condenser 29' magneto orior every current surge.

It will be seen from Fig. 20 that the transformer 234 again in this instance carries a distributor terminal 248'. In this figure it has been shown as a contacting terminal rather than as a sparking terminal, being spring urged against the terminals 252' connected to the spark plugs. The terminals 252' are, of course, flush with the cover 281 which may desirably be removably secured to the extension 282 of the base 214. Although this extension has been shown integral with the base, that of course is not necessary.

Although theelectrode 212 has been shown carried by the cover 281 and grounded through its holderand carrying tube (which would, of course, have a special connection with ground), it should be obvious that the positions of the parts could be reversed. In this case the electrode 212 might be connected to the condenser 28 and be positioned opposite a control element secured to the cover 281. As a matter of fact, the electrode 212 could be positioned directly adjacent the rim 282 instead of providing a special disc-shaped controller. 4

If the circuit ofFig. 1 is used, the secondarycircuit will normally have two spark gaps therein, namely the spark plug and the gap between electrode 212 and ring 213 ( contacts 38 and 32 of Fig. 1). There may be a very slight loss from including the gap of contact 212 in this secondary circuit. However, that can be avoided in this instance by the circuit modification of Fig. 12, in which the armature instead of being grounded is wired to the gap formed by the contact 38 so that ground may be used for the secondary circuit alone. The only disadvantage of this modification is that it makes something in the nature of a slip ring necessary in order for the magneto armature winding to be connected to both the stationary contact and the rotating contact. In some systems there would be a further inconvenience in not allowing the generator armature winding to be grounded, but that would not be an inconvenience in this instance except that neither electrode 212 nor ring 213 could be grounded.

Although the plate 262 could be a support plate secured firmly to the shaft 204 and not resting on the bearing 261, it is preferred that it serve instead as a bearing plate to facilitate the provision of extremely close clearances between pole faces 2119 and 230. It should be understood that either the stationary magnet elementor the ratating magnet. element may be ground flush with its associated bearing, while the pole faces on the other element may be ground or otherwise machined so as to be countersunk with respect to the associated bearing member. The amount that the pole faces are thus countersunk wlll'be the clearance between the respective pole faces and it is obvious that it may be an extremely small clearance. This is partly because of the fact that the bearing surfaces are so large that the wear will be extremely slight. A suitable oiling vent may be provided as shown or the bearings may be of the self-lubricating type.

The rotating element will be drawn firmly against the stationary element bythe magnetism of the permanent magnets 2118 and it is preferred that nothing other than the lubricating film should interfere with their coming into close contact and true parallelism so that full advantage of the small clearance above referred to may be had. To this end the rotating element is carried on the shaft 284' by a ball joint. the ball section 286 being formed on the shaft 2114, enough clearance being provided elsewhere along the shaft to permit a very slight swivel action which is the most-that would be necessary. A spring retaining member 238 on the end of the shaft 204' may be provided asan additional safeguard in holding the rotating element in place. Of course, the rotating element would be keyed to the shaft 284'. Since there will be practically no swiveling action, a large bearing surface engaging the ball 286 probably will not be necessary,

but, if it should be, it could be provided by a collar socket shaped internally for engaging the ball 288 and on which the bearing plate 262 is slidable.

It should be understood that the form of magneto shown in Figs. 15 to 18 could very easily be provided with a radial bearing similar to that shown in Figs. 20 and 21. In this case the stationary member including the magnets 208 might well be slidably and swivelly mounted on the shaft 284 and urged against the rotating element. The controller unit including the arm 242 could be moved radially outwardly so as to be positioned approximately between the pole faces of the armature and it could engage a ring on the outer edge of the fixed radial bearing which would extend approximately to the pole faces.

Polarity reversing ignition circuit In Fig. 2 I have illustrated a low frequency or unidirectional ignition circuit similar to conventional ignition circuits except that the current in the primary winding of the spark coil is reversed instead of merely being interrupted. A commu' tator 3114s provided which includes a plurality of segments 312 of insulation separating segments which are alternately connected to opposite sides of a battery as indicated by the and signs on said segments. The primary winding 314 of a conventional spark coil is connected across a pair of brushes 311 and 318 which engage segments of opposite polarity to cause a current to pass through primary coil 314, as the commutator 311 rotates, the conductive sections 320 and 321 will pass out from under the brushes 311 and 318, thus breaking the circuit for primary coil 314. If desired, a condenser may be connected across this coil as illustrated to prevent arcing at the brushes 311 and 318, and this condenser may be connected in a high frequency Refinements Although the foregoing description 'is sufflcient to give a good understanding of the invention, the following additional comments may behelpful to anyone who makes use of the invention.

All of the drawings are more ..or less diagrammatic. In Figs. Band 22, however, there is one detail which is quite important. This is the provision of an air gap at the edge of each live segment, the air gap preferably being formed by a slight groove in the insulation. The primary purpose of this air gap is to prevent the wiping of a-fllm of conductive material from the live segment onto the insulating segment with the result that there would be a sharp break as the brush left the live segment. A secondarypurpose is to facilitate sparking between the electrode and the live segment when the circuit is designed for such sparking. This sparking is aided both by the clean break resulting from the recess in the insulating material.'and also by the absence of any insulating material from the normal -path of the spark. This feature is covered by my Patent No. 2,059,237. It should be observed that the structure of Fig. 9 carries the recess to the extreme, since the recess extends from one contact or electrode to the other.

Under some circumstances it may be desirable to use two of the sources of current in Figs. 1 to 3" or high voltage battery could be used momentarily. Ordinarily it would be desirable to" switch. off one when the other is switched on, but this would not always be necessary.

be noted that the vacuum chamber could be connected with the intake manifold on either side of the throttlevalve. The description contemplates that it would be connected on the engine side of the throttle valve and if it were connected on the opposite side the effect would be somewhat reversed, but under certain circumstances that might be desirable for it might be desirable to connect it to both sides with a check valve in line to each side. 'With this double connection the spark would be advanced whenever there was suction on either side of the throttle. retard of the open throttle would be relatively less at higher speeds than at lower speeds. Even with only one connection to the intake manifold, a check valve in this connection might-be desirable so as to sustain a-vacuum at'the vacuumgap for a short time and so as to positively prevent combustible gas from getting into the vacuum spark chamber. As a matter of fact, however, the vent would prevent this by keeping the connecting line filled with fresh air.

If it be desired to use the vacuum gap and another controller as well,'the controller shown in Fig. 8 would be very suitable (assuming the wave shape of the magneto to be proper for automatic timing) because the controller of Fig. 8 would simply close the gap at the dead center position leaving the timing control otherwise to the vacuum gap.

' a nonstan't change of air whenever new air is available. Where these gaps are enclosed within v 4. An ignition system including a source of high-- Thus the I The desirability of changing the air in a'sparka housing. as within the flywheel in i5 I 18 and within the housing in. Fig. '20, it may be c could be accomplished simply by providing vents,

' desirable to provide some means for insuring a gradual change of air within the chamber. This preferably one near the axis of rotation, andone or more 'at the periphery of the housing in line with some rotating part whereby centrifugal force will insure a proper circulation.

One advantage of the electrolytic interrupters which has not been brought out clearly isjtheir I high frequency of operation, which would result in a large number of successive kick voltages being I appliedto the ignitioncircuit during the ignition in a single cylinder. This would be very valuable first spark. The large bearings of Figs. 12 to 14 and the large radial bearings of Figs. 20 and 21 (and of Figs. 15 to 18 ifoptionally included therein) permit an amazing reduction in the length of the magnetic gap with safety. It is entirely possible to make. a commercially satisfactory magneto which will run more or less indefinitely with a gap of 1/1000 of an inch or as heretofore commercially practical magnetos have. had to have a gap of about 6 to8/l000. Those which'had a smaller gap than this had a life say in the neighborhood .of fiftyhours. a r

The disclosures of this'applicajtion are illustrativeand the invention is not to be limited by them. In fact, if modifications or improvements are not at once obvious, they may be devised in the course'of time to make additional useof the broad ideas taught and covered by this application. 'The'claims are intended to point out novel features and not, to limit'the invention ui' d b ri rt.

In connection with the vacuum gap it should may be re y p or ,ing circuit in inductive relation to said primary oscillating'circuit and including a condenser in common therewith, and an ignition spark gapall connected in series.

so i 2. An ignition system including a primary osv cillating circuit including a primary winding of a high frequency transformer, a condenser in series therewith and a grounded spark gap in series with said winding and said condenser; and a secondary oscillating circuit including a secondary winding of said transformer, said condenser and an ignition spark gap in series therewith, and a return through said ground and said first mene tioned spark gap" but independent of said primary winding.

3. An ignition system including a source of high. I

voltage current; a primary oscillating circuit ine eluding a condenser and the primary winding of a high frequency transformer; a controller for normally keeping said primary circuit open and for rendering said primary circuit effective .by

substantially closing it when ignition is desired,

said condenser being connected to be energized by said source of power whensaid controllermakes said primary circuit effective; and a secondary circuit including the secondary winding of said high frequency transformer.

- of said transformer and a common condenser in series with each of said windings.

5. An ignition system for a combustion engine having a piston and an ignition spark gap, including a magneto synchronized with said piston; an interrupter normally forming a short circuit for said magneto whereby a heavy current is built up in said magneto having a wave-form synchronized with the. piston, said interrupter being effective at a given current value to interrupt said short circuit whereby a kick voltage is produced in the winding in said magneto; and means for rendering saidkick voltage eflfective to produce a spark at the ignition spark, gap of said engine.

6. An ignition system for a combustion engine having a piston and an ignition spark gap, in-

cluding a magneto synchronized with said piston;

an electrolytic interrupter normally forming a short circuit for said magneto whereby a heavy current is built up in said magneto having a wave-form synchronized with the piston, said interrupter being effective at a given current value to interrupt said short circuit whereby a kick voltage is produced in the winding of said magneto; and means for rendering said kick voltage e fiective to produce a spark at the ignition spark gap of said engine. I

7. an ignition system for a combustion engine having a piston and an ignition spark gap, including a magneto synchronized with said piston; an interrupter normally forming ashort circuit for said magneto whereby a heavy current is built up in said magneto having a wave-form synchronized with the piston, said interrupter being effective at a given current value to interrupt said short circuit whereby a kick voltage is produced in the winding in said magneto; and means for rendering said kick voltage eifective to produce a spark at the ignition spark gap of said engine, said means including a' high frequency transformer having primary and second-, ary'windings, a primary'oscillating circuit 'including said primary winding and a condenserin series therewith and a secondary oscillating circuit including said secondary winding and said condenser and the ignition spark gap all. in series.'- i

8. An ignition system for a combustion engine having a piston and an ignition spark gap, including a magneto synchronized with saidfplston; an electrolytic. interrupter normally forming a short circuit for said magneto whereby a heavy current is built up in said magneto having a in series'therewith and a secondary oscillating circuit including said secondary winding and said condenser and the ignition spark gap allin series.

9. Apparatus for producing successive. long value to interrupt said short circuit whereby a 1 trains of sparks comprising a source of high direct voltage, a high frequency transformer having primary and secondary windings, a primary oscillating circuit including said primary winding and a condenser, means to discharge said condenser between trains of sparks and to apply said high voltage to it while it is discharged to set up oscillations in said circuit. and a secondary circuit including said secondary winding.

10. Apparatus for producing successive long trains of sparks comprising a source of high direct voltage, a high frequency transformer having primary and secondarywindings, a primary oscillating circuit including said primary winding and a condenser, means to discharge said condenser between trains ofsparks and to apply said high voltage to it while it is discharged to set up oscillations in said circuit, and a secondary circuit including said secondary winding, and a condenser also included in said primary oscillating circuit.

11. The combination oi a'combustion engine denser Between ignition sparks to permit the timing to be controlled solely by said generator and said gap.

12. The combination of a combustion engine having a piston and a wave-form timing igni-- tion system including a generator producing a voltage wave havingits peak synchronized substantially with the dead center iiring position of each piston; an oscillating circuitincluding a condenser and a timing spark gap; and means to causean. ignition spark in response to oscillations in said circuit, said gap including a stationary electrode and a rotor separated therefrom during the production of each of said voltage waves approximately until the dead center position is reached, but being shaped to reduce the length of the gap micrometrically before that time.

13. The combination of a combustion engine I having a piston and a wave-form timing ignitioraksystem including a generator producing a vol e wave having its peak synchronized substantially with the dead center firing position of each pistonpan oscillating circuit including a condenser and a timing spark gap; and means to cause an ignition, spark in response to oscillations -in said circuit, said gap including a stationary electrode and a rotor separated therefrom during the productionof each of said voltage waves approximately until .the dead center position is reached, and then ensu said electrode to insureoscillations even though the voltage be weak.

14. An ignition system including a generator having a rotatingarmature winding; a high frequency transformer rotating therewith and including primary and mecondary windings, a

primary-"oscillating circuit includingsaid pri-' mary winding and a condenser rotating therewith and energized bythe armature winding; and a secondary oscillating circuit including said secondary winding and an ignition spark gap.

15. The combination of a combustion engine having a piston and a wave-form timing ignition system including a generator producing a voltage wave having its; peak synchronized with a predetermined position of the piston, an oscillating circuit including a condenser andatiming spark gap,'ar-idmeans to cause an ignition spark in response to oscillations in said. circuit, said gap arid-said-magneto being so constructed as to re-.

I duce the. advance in 'timing -of the-spark upon speeding up ofthe-engine andgenerator below the advance whichwould be produced with a sine-wave wave shape and a constant spark gap.

16. The combination of a combustion engine having a piston and a wave-form timingignition system including a generator producing a voltage wave having its peak synchronized with a predetermined position of the piston, an oscillating circuit including a'condenser and a-timgap, means to causean ignition spark-in response to oscillations in. said circuit, and means for causing an advance in ignition timing by reducing the air pressure within the spark gap in response to certain motor conditions.

18. The combination of a combustion engine having a pistonand a. wave-form timing ignition system including a generator producing a voltage wave having its peak synchronized with a predetermined position of the piston, an oscillating circuit including a condenser and a timing spark gap, means to cause an ignition spark in response to oscillations in said circuit, and means for causing an advance in ignition timing by reducing the air pressure within the spark gap in response to certain motor conditions, said means I including a housing about said spark gap, and a conduit connecting said spark gap with the intake manifold of the engine for drawing air from said housing; said housing having a restricted air inlet'therein to provide a change of air in the air gap-even with constant manifold suction.

19. A high frequency oscillating system including a spark gap, a housing around said spark gap, and means for drawing air from said housing to cause said spark gap to function in' a partial vacuum, said housing being provided with a restricted air inlet to cause a change of air within said spark gap.

20. An ignition system for a combustion engine having a piston, an intake manifold, and an ignition spark gap, including means for producing a rising voltage at approximately the time an ignition spark is desired, including a spark gap for producing such ignition spark when the voltage reaches a value sufiicient to jump said ing ageneratorwhose voltage wave form. is synchronized with said piston, said system including.

a transformer of which the primary winding carries the generator current, and electrical means responsive to a predetermined voltage output of the generator and adapted to control the primary winding to induce a. high voltage in the secondary winding of the transformer, thereby producing a spark at the ignition gap, said means providing for an automatic advance in the timing of the spark upon speeding up of the engine.

22. An ignition system for a combustion engine having a piston and an ignition spark gap, including a generator whose voltage wave form is synchronized with said piston, electrolytic means '7 for normally v short-circuiting said generator whereby a heavy, current is built up in the winding thereof having its wave form synchronized with the piston, said means being effective at a given current value to interrupt said short circuit to produce a sudden change in the magnetic field thereof, and means responsive to said sudden change to produce a spark at saidignition spark gap.

23. An ignition system for 'a combustion engine having a piston and an ignition spark gap, including a generator whose voltage wave form is synchronized with said piston, electrolytic means for normally short-circuiting said 'generator whereby a heavyvcurrent is built up in the winding thereof having its wave form synchronized with the piston, said means being effective at a given current value to interrupt said short; circuit to produce a sudden change in the magnetic field thereof, including a secondary coil having a high voltage induced therein'as av result of said sudden change for producing a spark at the ignition spark gap.

ing its wave form synchronized with thepiston,

said means being efl'ective 'at a given current value to interrupt said short circuitto energize the secondary winding and produce a spark at e the ignition gap of said engine.

25; Apparatus for producing successive long trains of sparks, comprising a source of high direct voltage, a high frequency transformer having primary and secondary windings, a primary oscillating circuit including said primary winding and a condenser, and means to connect said source across said circuit successively in opposite polarity for successive trains of sparks whereby any charge which the source leaves on the condenser in producing one train of sparks will be discharged by the source as it is next connected to the condenser.

26. An ignition system for an internal combustion engine having a piston, including a generator producing a wave having its peak synchronizedwith a predetermined position of the enginepiston,and electrical means for effecting an ignition spark at a predetermined value of the generator output, said generator being so 'constructed as to produce a wave form substantially different in shape from a sine wave.

27. An ignition system for an internal combustion engine having a piston, including'an engine spark gap and a generator which produces a wave having its peak synchronized with a predetermined position of the engine piston, and

a predetermined position of. the engine piston, and a spark gap of variable resistance for automatically regulating the timing of the ignition spark in response to engine load and throttle conditions, said generator being so constructed as to 5 produce a wave form substantially different in shape from a sine wave.

HARRY B. HOLTHOUSE.

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