US1848322A - Magneto-electric generator - Google Patents

Description

March 8, 1932. 3, ox 1,848,322

7 MAGNETO ELECTRIC GENERATOR Filed Nov. 22, 1929 INVENTOR HENRY 6. Cox

ORNEY Patented Mar. 8, 1932 UNITED STATES PATENToFFIcB" HENRY o. cox, or IBELOIT, isconsin, ASSIGNOR cnroaeo, ILLINOIS, A conromnouor rumors T rammmxs, "loner: a;

MAGNETQELECTRIC dramas-ma Application filed November 22, 1929. Serial No". 409,035.

This invention relates to improvements in magneto-electric generators such as are employed for igniting combustible mixtures 1n the cylinders of internal combustion engines.

6 An object of the present invention is to rovide an improved magneto in'which is emiiodied means for rendering certain mechanical partsot' the-device inoperative during certain'portionsof the armature rotation, in or- 10 derto prevent generation of unused electrical impulses, whereby to minimize wear and "deterioration of the parts ofthe device.

A further object is'to provide'simple'and effective means'for readily and easily vary- 16 ing the angular relation between the breaker device and the breaker actuating cam of a magneto, to eflect instantaneous and efficient timing of the spark impulses, relative to the engine with which the magneto is employed.

A still further objectis an improvedprovision for producing, and for timing the production of spark impulses in a magneto for igniting the combustible charges in thecylinder of an internal combustion engine having irregular firing sequences. 2 An additional object is to provide animproved magneto which is neat and compact in" arrangement, is economical to construct and reliable in its operation. Further objects and advantages will appear fronrthe following. detailed description of parts and the accompanying drawings, in whicln. v

' I Fig. 1 is a sideelevation, partially in section, of a preferred form of magneto to which certain of the present improvements are applied; Fig. 2 is a diagrammatical end elevation, as viewed from line2-2 in Fig. 1; Fig. 3 is a diagrammatical showing as viewed from 40 line in Fig. 1, showing the timing arrangement in fully retarded position, I and Fig. 4 is a diagrammatical showing as viewed from line 3'-3-in Fig. 1 and shows theadvanced position of certainof the timing parts. It will, ofcourse, be-understood that the present detailed description of -parts' and the accompanying drawings relate to a single preferred executional embodiment of the invention and that substantial changes may be made'in the described constructionand arrangement of parts withoutdeparting from the spirit and full intended scope of the dis closure as defined by the appended claims.

Certain features of the magneto to be described aneof conventional of the invention hereinafter described in tail, 1s I continuously rotating in one direction between bipolar permanent magnets, the latter The 7 being of conventional horseshoe form. armature, according to the present example,

is of so-called high-tension type, and is constructed in the form of a-metallic spool on which. are wound primary and secondary coils, the arrangement being suchthat thereoccurs, twice 5 per revolution of the armature shaft, apposition at which the axis of the coils is substantially. parallel to the flanks of i form and believed to be well known in the art, for example, the .inagnet-o constituting the particular examgle provided with a bipolar armature the-usual timed relation, and as well understood in the art.

By way of further reference to the object first set forth above, it may be noted that the older. prevailing types of magneto, when driven at crank shaft speed by a four-cycle engine, produce twice the number of electrical spark impulses necessary for a single cylinder engine, each alternating impulse oc? at the end of the excurring substantially haust stroke. This waste of impulses is, of course, normally without effect upon the operating cycle of the engine: It may, however, give. rise to a certain inconvenienceand danger'during starting ofthe engine, since gasoline introduced into the cylinder for priming purposes, may be ignited at a; time when the valves are open, thus occasionally permitting ignition of charges in the muflier and exhaust passages, fr'equently causingexplosions' and fires. Previous unsatisfactory attemptshave been made, to nullify this action by providing means .for causing the wasted spark to take place at some point outside of the power cylinder. The present invention meets this difiiculty by preventing the generation of unnecessary electrical impulses, rather than by providing means for nullifying their effects.

The construction in which a magnet-o having a rotating armature is prevented from generating undesirable or unnecessary igniting impulses, is of particular value in connection with imilti-cylinder engines which, although operating on a uniform cycle, are required to provide electrical impulses for ignition purposes, at irregular intervals. Such a situation arises, for example, in a magneto for application to a two-cylinder four-cycle engine, in which the cylinders are arranged side by side and in which the cranks are a-ngularly spaced at 180 degrees. In such an engine the firing impulses are separated by 180 degrees of crank shaft rotation, followed by a non-firing interval of 540 degrees. In other words, one working stroke of the engine precedes the succeeding working stroke by 180 degrees, the two working strokes being followed by two idle strokes. During each of the idle periods of the engine, the magneto armature passes positions of a high E. M. F. at which a spark impulse would be produced, if the breaker mechanism in the primary coil circuit of the magneto were permitted to function. The arrangement to be described retains the breaker assembly in open circuit, inoperative position, during the idle periods of the engine to which it is applied. It will be understood, however, that, while for convenience there is described an application to a specific engine of the type noted, the same principles and substantially the same arrangement may be employed on engines of a variety of other types, or example, two cylinder V type engines, as used on motorcycles, the example described being considered as particu- H larly applicable to multi-cylinder internal irrespective of whether it may be combustion engines having a non-uniform firing sequence, due to a particular relation of cranks or cylinders.

The preceding preliminary discussion of the general principles underlying the present disclosure, has been presented to effect a better understanding of the structure and operation of the interrupting means and other operating elements of the magneto to be described. Certain other features of the present invention, for example, the means employed for advancing and retarding the timing of igniting impulses, is regarded as entirely practical of application to a mag-- neto for use on any usual type of engine,

employed with one or a number of power cylinders, operating on a cycle in which the ignition impulses oecur regularly or irregularly.

Referring by numerals to the drawings of the particular disclosure, 10 designates, generally, a magneto of any conventional form, which includes, by preference, a frame 11 in which is mounted a permanent magnet 12 of any suitable form. An armature appears at 13, the essential features of which may be of usual form, and extending from end portions thereof are armature shafts 14: and 15. The shaft 15 may be in operative association with the crank shaft of an internal combustion engine (not shown) or with any suitable driving apparatus.

Upon an end face 16 of the armature 13 is carried, by preference, a breaker bar 17 (Fig. 2), which is fulcrulned on a pin 18 fixedly secured to the armature. An end of the bar 17 is provided with a contact point 19 which is arranged for movement relative to a contact point 20 adjustably attached to the end face of the armature. The point 20 is, by

preference, insulated from the armature, but

is in electric connection with the usual low tension winding (not shown) on the armature. The oscillating movement of the breaker bar 17 about its pivot pin 18, is produced by means of a rubbing block 21 which is secured to an end of the bar 17, and which follows the outer surface of a cam 22 under the influence of a spring 23. It will be apparent that by providing a suitable camming surface on the cam 22, ing movement of the breaker bar 17 may be attained. In the present, preferred example, a pair of cam depressions 24 am 25 are provided, which are so related to the interrupting means as to cause two interruptions of the current separated by substantially degrees of relative rotation between the cam and the bar 17, the remaining cam surface being substantially circular. with the axis of rotation of the shaft let as a center, and formed on such a radius that the points 19 and 20 are kept open during the greater part of the cycle of armature rotation, and closed only during the brief intervals when the rubbing block 21 comes opposite the low points of the cam 22. As will hereinafter appear, both the cam 22 and the breaker point assembly are normally rotated in the same direction, but at different rates.

The cam 22 is, by preference, freely rotatable on the shaft 14. being mounted on ball bearings 26. This cam is operatively driven by, and rotated relative to the armature shaft 1st in the following manner: A gear 27 is, by preference, keyed to the armature shaft 14, and meshes with a gear 29 which is rotatably mounted on a shaft 2!). The gear 28 is, by preference, rigidly attached to or formed integrally with a gear 30, thereby forming a combined idler gear. which meshes with a gear 31 forming an cxtended portion of the rotating assembly in cluding cam 22. In the preferred example. the gears 27 and 28 are provided with an identical number of teeth, and due to the fact any desired oscillat-' speed as the armature shaft 14. But the gear 6,310. is'provided with a smaller number of .teeth 1 t ran the gear'3l with which it m'eshes, for ex ample, to effect a two-to-one driving ratio,

7 and therefore the gear 3l:and cam22-rotate,

in the present instance, at half the speed of the armature shaft 14. It' will be apparent that by using the combined idler gear 28.30, the speed of the cam is not only'reduced to half that of the armature,but that the cam is driven in thesame direction of rotation as the armature, and hence in the same direction of rotationasthe breaker assembly.

It will appear from this construction that the relative speedyof the cam 22; and the breaker assembly, particularly the rubbing block 21, is only a fraction of the relative speed otherwiseexistingbetween a stationary interruptor assemby and a cam rotating at armature speed,'or vice versa. -:By this expedient, wear is minimized between the cam and the rubbingblock, and, as willherelnafterappear, the. shape of cam 22' is such that the breakerarmf17 is actuated only at the time when anignitingimpulse is useful and necessary. I l V. As noted above, the idler gear 28-30 s rotatably mounted on the shaft 29. .Th s shaft fixedly secured to an arm 32 which is capable of a limited range of rotat-ive movement, in the present showing about the same a\is as the armatureshaft 14. This-arm is journaled in a removable end closure 33and further cooperates with this closure to projvide afjournal or cage for rollferbearmgs 34. It thus appears that the closure and arm 32coactto constitute a Journal structure containing the bearing 34 and theouter end of shaft 14,.besides servingin part to house the timing and breaker assembly. Up-

onan' outer end35 of the arm is keyed-a lever may be an- 36 by means of which the arm 32 gularly displaced fol-timing purposes, with respect to the shaft 14 or armature 12. Stop lugs 37 are, by preference, ad nstably secured to the. frame 11,-to provide means for limiting the movement'ofthelever 36. It will be readily seen that angular movement of the arm 32 about the shaft 14 does not disturb the mesh of thegears 27, 28, 30 and 31, but thatsuch movement does produce a limited rotation of the compound idler 28-30, relative to the armature andgear 27, and consequently serves to rotateto a. small extent, the gear 31 andcam 22. This rotary movement being imparted'toth'e gear31 and'ca'm 22, the angular relationship between the cam 22 and the rubbing block 21 is alte'red,'w'ith the obvious effect of retarding or advancing the time of breaker point movement, for

spark timing purposes.

" The operation ofthe interrup'tor assembly,

with particular reference to the cam 22 and move to'the dotted position power cylinders of the provided, over the brea'ker :arm 17, .is thought to be apparent from theabove' descriptionof parts and their relation, but maybe briefly described for sakeof completeness. Assuming a clockwise rotation-of the shaft 14, cam 22, and hence the breaker assembly, all as viewed in Figs. 2,

'3 and 4,21 reference marker 38 is employed in Figs. 3 and 4-to' indicate, in the present cause an effective actuation of the breaker? points tointerrupt the primary circuit of the armature after it has been previously closed by the cam, insuch a manner as to cause an electrical impulse for ignition purposes.

Since the-cam 22 rotates at half the speed of the breaker point assembl point 38 will shown in Fig. 3, while point39 moves to its dotted position appearing in the same figure, thus causing at the time of coincidence of points 38 and 39, an impulse producing a spark in one of the engine.

Fig. 2 that the cam 22 greater portion of its periphery," with a circular surface constituting a. relatively high area adapted to main- It will appear from tain the breakerpoints 19 and 20 in open position. i Actuation of the breaker arm first takes place to closethe points, after which the subsequent high portion of cam 22 serves again toopen the points, with the effect of producinga spark impulse.

Referring to the diagrams appearing in Figs. 3 and 4, the operation of the timing control may be readily followed. In Fig. 3, for the purpose of description, the arm 32 may be seen in its full retard position, with its center line'substantially offset to the clockwise side of the magneto center line. In this position, the armature has a momentary position ahead of the vertical center line, as indicatedxby thereference marker 38. It will be readily seen that a point on the cam, by which the breaker is actuated to cause a s ark impulse, is" indicated by marker 39. ince the armature rotates at twice the speed of the cam, an ignition impulse will take place substantially at the point indicated by the dotted positions of the markers 38 and 39.

- In Fig.4 the timing has been changed by moving the arm 32and its relatedparts, ina counterclockwise direction, relative to the vertical center line. The'armature reference marker 38 still remains at the position shown in full lines-in Fig. 3, but the cam, due to the gearing relation, has .been moved counter block 21. A corresponding refer--' of Qthe armature to be rethe cam reference marker substantially at the point indicated by the dotted position of the markers. It will be apparent that the armature has rotated an angular distance substantially twice the corresponding angular rotation of the cam. At the position indicated in dotted lines, the interruption of the prin'iary current causes in a well known manner, the production oi? a high tension ignition current. It will be readily seen from Figs. 3 and 1, that the ignition takes place earlier or more advanced, in the position shown in Fig. 1, than the case with the timer in its full retard position, as appears in Fig. 3. That the timed relation of the spark impulse, relative to the cycle of operation of the engine, is changed by movement of the parts from their positions indicated in Fig. 3 to the position shown in Fig. 4, will be apparent from the fact that the angular relation between the position of coincidence of markers 38 and 39, and the vertical center line, is substantially less in Fig. 3, than is the corresponding angle of Fig. 1.

In order to distribute the spark impulse to the desired cylinder, a collector ring 40 is provided, which is keyed to the armature shaft 15. This ring is, by preference, provided on its periphery with a contact segment 42 and a non-conducting segment 41. The segment #12 is, by preference, in electrical connection with the armature secondary, (not shown) and is so disposed in respectto a pair of collector brushes a3 and 4 1 as to be in engagement with one of the brushes when a cam depression is operatively associated with the breaker bar. By this provision, the spark impulse may be distributed to the desired cylinder by means of leads 15 or 46 in the desired tiring sequence.

In the preferred device described, the arrangement for varying the timing of the spark impulses, is constituted by the same novel arrangement of parts used in the production of the irregular ignition impulses. For it will be observed that the timing is attained without disturbing the meshed relation of the gearing between the interrupting means, nor the half speed trailing motion of the cam. Further. any desired degree of timing may be easily and readily effected during operation of the magneto and an associated engine. It will be understood that the described device is subject to various alterations without appreciably affecting the operating principle. For example. the cam depressions 2a and 25 may be disposed with their active points at any desired angular relation, in order to effect any desired tiring sequence in multi-cylinder engines.

It will be apparent that the described device is simple and compact in arrangement. and that a minimum number of parts is used to effect an irregular firing sequence and the timing thereof. Further. the parts are readranged for rotation coaxially with the armature, and adapted to cause interruptions of an armature circuit substantially coincident with certain of said maxima, said means adapted, through said cam and interruptor, to keep said circuit open, whereby to prevent an interruption of the ari'nature circuit during another of said maxima.

2. In a magneto adapted for use with an engine requiring irregularly spaced ignition impulses, a circuit interrupting device including a cam. a breaker element, means for rotating said cam and said breaker element relative to each other, for actuating said breaker, a member adapted for actuating said means for timing purposes, and means constituted I by said device for preventing effective actuation of said breaker element, except in synchronism with the firing periods of an engine with which the magneto is employed.

3. In combination in a bipolar magneto, a N

bipolar armature. circuit breaking means carried thereby a cam adapted to rotate at half the speed of said armature. for actuating said circuit breaking means, said cam having portions adapted to maintain said breaking means inoperative, and two portions adapted to operate said breaking means, said opera tive portions subtending an angle of 90 degrees with respect to the axis of rotation of said cam.

4. In a magneto including a rotatable ari mature, and an interruptor for an armature circuit. a rotatable cam disposed coaxiallv with respect to the armature and arranged to efiect a plurality of separate movements of said interruptor during a given half revolution about its axis.

5. In a magneto. an armature. circuitbreaking means for the armature circuit arranged ior rotation with said armature, and

an interruptor member adapted to revolve at a speed different from the speed of the arm a ture and adapted repeatedly to actuate said circuit-breaking means. within a given half revolution of said interruptor member.

6. In a magneto. an armature. opening and closing means tor a circuit carried by said armature. and means carried by the arn'iature and rotatable relative thereto. said last named means adapted operatively to engage the c actuate said circuit opening and re ular intervals.

I. In a magneto, means carried by closing means at ira rotatable a-rmaiture, the armature for interrupting the armature circuit, means, adapted to be rotated by and at a speed different from that of the armature, adapted operatively to interruptor means and'a timing member adapted to move said means relative to each other. I

8. In a magneto including an armature, circuit-breaking means carried by said a rma ture, means arranged to rotate at other than armature speed, for actuating said circuitbreaking means, said circuit breakingand actuating-meansbeing arranged for timing movement relative to each other, independently of rotation of said armature.

9. In a magneto, circuit-bearing means for the armature circuit, a cam for actuating said circuit breaking means, said cam and breakingmeans beingarranged for differential, unidirectional rotation, and means for varying the timed relation between said cam and circuit breaking means.

10.In a magneto, a. rotatable armature assembly including a shaft, a circuit breaks er and a cam for actuating said circuit breaker, said cam and circuitbreaker being car-, ried by said armature assembly, and means for rotating from that of the circuit breaker.

11. In a magneto, an armature assembly including a shaft, a circuit breaker and a cam for actuating said circuit breaker, said cam and circuit breaker being carried by said armature assembly, and means for rotating said cam at a speed different from that of the circuit breaker, said cam being constructed to maintain said breaker in open position during the major portion of revolution of the cam and to actuate said breaker only tion.

12. In combination in a magneto, a revolving armature, circuit breaking means carried thereby, a cam member adapted to revolve at a speed other than the speed of said armature, said cam member having a plurality of relatively projecting portions adapted to be brought into operatiy e engagement with said circuit breaking means, at irregular intervals.

13. In a magneto, an armature, circuit breaking means, a cam for actuating said circuit breaking means, a gear operatively associating said cam and breaking means, and a pivoted lever carrying said gear.

14. In a magneto, an armature, circuit breaking means carried thereby, a cam for actuating said circuit breaking means, a gear train operatively relating said armature and cam, and means for shifting the axis of one of the gears in said train. I

15. In combination in a magneto, an armasociating said cam at a speed different during a minor portion of such revoluture, circuit breaking means carried thereby, a cam adapted to actuate said circuit breaking means, a gear tram operatively asof the gears of said train being adapted for rotation relatively to, and about an axis of rotation of'another of said gears.

. 16. In a magneto, including an armature assembly, a contact breaker, a cam, adapted for actuating said breaker and carried by the armature assembly, and a timing member adapted for movement to vary the relation between said cam and breaker assembly and constituting a journal for the armature assembly.

17. In combination in a ture including an armature shaft, circuit breaking means carried by the armature, a cam for actuating said circuit breaking means, a gear adapted operatively to connect said circuit breaking means and cam, a pivoted arm forming an axis for said gear and constituting a journal for said armature shaft.

HENRY G.

magneto, an armasaid armature and said cam, one

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