US1489382A

US1489382A - Magneto

Info

Publication number: US1489382A
Application number: US480348A
Authority: US
Inventors: Brown Phelps; Harold H Clark
Original assignee: WICO ELECTRIC CO
Current assignee: WICO ELECTRIC Co
Priority date: 1921-06-25
Filing date: 1921-06-25
Publication date: 1924-04-08
Anticipated expiration: 1941-04-08

Description

April 8 1924. 1,489,382

P. BROWN ET AL MAGNETO Filed June 25 1921 4 Sheets-Sheet 1 INVENTOR BYZZ I ATTORNEYS April 8 1924.

P. BROWN ET AL MAGNETO Filed June 25. 1921 4 :Sheets-Sheet 2 [MENTOR fijgj; m

ATTORN EYS April 8, 1924.

P. BROWN ET AL MAGNETO Filed June 25, 1921 4 Sheets-Sheet 5* R O N E V m ATTORNEYS April 8 1924. 1,489,382

P; BROWN ET AL MAGNETO Filed June 25 1921 4 Sheets-Sheet 4 W YW- ATTORNEYS Patented Apr. 8, 1924.

PHELPS BROWN AND HAROLD H. CLARK, CLARK ASSIGNOB TO WICO ELECTRIC 0F SPRINGFIELD, MASSACHUSETTS; SKID COMPANY, OF SPRINGFIELD, MASSACHU- SETTS, A CORPORATION OF MASSACHUSETTS.

MAGNE'IO.

Application filed June 25,

To all whom it may} concern:

Be it known that we, Pncnrs BROWN and Hnnom ll. Cmnn, citizens of the United States, residing at Springfield, in the county of Hampdeu and State of Massachusetts, have invented new and useful Improvements in Magnetos, of which the following is a specification.

This invention relates to improvements in lnagnetos and is especially directed to magnetos of the type wherein a reciprocating armature moves into and out of engagement with magnetic poles to vary the flux in a magnetic circuit and by such variations to cause the generation of electricity in a suit able winding.

The invention is particularly concerned with mechanism "for actuating the armature in a novel mannen, Heretofore, it has been thought essential, in magnetos of the type described, to apply to the armature very suddenly, it not p 'actically instantaneously, a relatively high initial force to dislodge the armature from its poles and overcome the opposing force due to magnetic attraction. Hence, the use of the hammer which, when suddenly released, is driven toward the armature and, after acquiring considerable momentum, engages the latter with an impact which sets the armature suddenly in motion at high speed. Such actuation of the armature was considered necessary in order to provide for a rapid change in flux in the generating windings. Other prior art magnetos of the type under consideration, while dispensing with the hannner, have nevertheless retained the sudden and practically instantaneous release of the armature to allow the sudden application ofa considerable initial driving force.

This invention is concerned, broadly, with im n'ovements in magnetos of the type in which an armature is moved into and out ofcontact with magnetic poles and a driving mechanism is provided to build up on the armature, while held to its poles, a differential of force to disengage it therefrom. This difi'erential, by reason of its infinitesimal .initial value, is not capable of moving the armature away from its poles at high speed, but, as soon as the least air ga) is estab lished between the armature-aml its poles, the difl'erenlial is increased considerably and continues to increase very rapidly until 1921. Serial No. 480,348.

within a very short time it becomes effective to rapidly move the armature. This in crease in the differential is due to the rapid weakening of the resistance to armature movement, which resistance includes as a principal element the force of magnetic atthe force of magnetic attraction until the driving means becomes effective to move the armature.

According to this feature of the invention, the armature may be deposited on its cores by any suitable mechanism, which, once it has deposited the armature, may then withdraw, leaving the armature held in place by magnetic attraction. This condition will then continue until tl'ie inagnetic hold on the armature is broken, after which the driw ing means, being new superior to the weakened force of magneticattraction, will drive the armature away from the cores at rapidly increasing speed in the manner above out lined.

An important advantage results from this mode oil operation due to the lessening of the force of the driving n'ieans, usually a spring, the maximum tension of which is less than the rnaxin'nu'n force exerted on the armature. This diminution in the strength of the drive spring means that less force is required to oppose it and a reduction in this force means a lessening of the wear on the parts.

Another imiortaut advanta e of this mode of operation is that the meeliauisn'l used to deposit the cores on its poles may be relatively slow acting in withdrawing from its poles,that is. it need not withdraw practically instanlaneously. as has heretofore been common, for the armature, being held to its poles indepei'idently of such mechanism, can dwell in such position until the relatively slow acting mechanism has had time to get our oi the way, in so far as interference or obstruction to the high speed movement of the armature is coneerned. Thus, the reciprocating mechanism of the magneto may be chosen with a View to its quietness in operation. T he usual arrangement of a cam, which periodically releases its follower for a free and practically instantaneous fall, is no longer necessary and much less violent motions may successfully be used, retaining the substantial advantages of the reciprocating armature type of n'iagnetos without the usual disadvantages of undesirable noise and rapid wear of parts.

Another object of the invention is to provide an actuating mechanism for the arma-- ture, whereby, when the armature is seated on its poles, the armature driving spring is under no tension, or substantially none. and whereby, previous to the breaking of the magnetic hold on the armature the driving spring is placed under the desired tension.

Another object of the invention is to provide, in a magneto of the type set forth, adjustable means for breaking the magnetic hold on the armature, or tripping it, at various times after its deposit on the cores. whereby variations in timing of the currents generated may be effected by varying the time when the armature is released for its flight away from the poles.

According to this feature of the invention, the tripping means may be made inde pendent of the mechanism for depositing the arn'iat-ure on its poles and this is important, for variations in timing may be effected without changing the timing of the armature-depositing mechanism.

Another object of the invention is to connect the tripping mechanism for actuation by the depositing mechanism for the purpose of avoiding unnecessary multiplication of parts.

Other objects of the invention relate to improvcmcnts in the construction and arrangement of parts and will appear in the following description and in the illustrative en'ibodiment of the invention in the accompanving drawings, in which,-

Fig. 1 is a. fragmentary elevational view showing the mounting of the magneto on an engine;

Fig. is an enlarged front. elevational view of the magneto with the casings removed. to show the interior;

Fig. 3 is a cross-sectional view of the magneto;

Fig. iis a bottom plan view of the magneto with the armature and associated moving parts removed;

5 is a diagrammatical view of the electrical connections of the magneto:

Figs. 6, T, S. and 9 are diagrammatical views illustrative of successive steps in the operation of the breaker-points, which control the opening and closing of the chokecoil circuit;

Figs. ti, T, 8, and 9 are diagrammatical views showing the relative positions of the armature and poles which obtain when the breaker-points are in the respective positions shown in Figs. (5, T, S, and 9;

Fig. 10 is a top plan view of a part of the interrupter-actuating mechanism:

Fig. 11 is a view, taken similarly to Fig. 3, showing modifications in certain parts of the magneto; and

Fig. 12 is a top plan view shown)" a modification of the structure shown in I ig. 10.

In these drawings. there is shown, in full detail, an embodiment of the invention incorporating many desirable l'caturcs rclating to the particular construction and arrangement of various parts, which. although important and preferred, are not essential as far as the broader aspects of the invention, heretofore outlined. are concerned. As to each of the latter, the showing is to be taken merely as an illustrative example of one of many suitable types of magnctos, in which they may be embodied.

The magneto includes a group of stationary parts. such as the magnetic source. cores, and coils, which may be supported in any suitable manner, as by a bracket u, from the engine frame. as 7), and a second group of movable parts, such as the armature and associated mechanism. which may be actuated from the engine by various means. ()ne illustrative example of such means is shown in Fig. 1. Thus. the crank shaft. of the engine. indicated at c, drives the canrshaft d, as by gearing c. at the (lo-- sired ratio of speed. The cam-shaft (I has mounted thereon a cam 7. which in this particular instance is shown as an ccccntric. as an example of the most quiet and most smoothly acting cam that is available. \Yhile other types of arms. or actuating means other than cams, may be uscd. the eccentric is preferred for its rclative quietness and smoothness in operation. \Vith the use of an eccentric the direction of rotation of the cam-shaft becomes immaterial.

The statitmary group of parts includes a back frame 15, from which all the otlicr parts of this group are su 'iportcd. This mcmbcr 15. which of non-magnctic material. is provided with tapped holcs it; to permit its attachment to the bracl-Ict o described and also with a forwardly-cxicnding boss 17. Mounted in and secured to the latter, as by the screw 18, is a rod in. which extends downwardly below the lower edge of the frame and forms a guide for the moving parts of the magneto.

The source of magnetic flux. in this par ticular instance. comprises a series of perinancnt bar-magncts 20 arranged in superpostnl relation and grouped into a unit for con Ill) venient assembly in the general manner disclosed in U. S. Letters Patent No. 1,335,119

ranted March 30, 1920, on an invention of G. Louis. That is, the ends of like polar ity of all magnets are received within substantially U-shaped clips 21, to which they are firmly held, as by shims or wedges 22. The clips 21, although of magnetic material, are not hard, as are the ma nets 20, and are readily drilled to receive t e attaching devices, later to be described. Various other means may be emplo ed for securing the magnets in place an the clips are givenmerely as an illustration of one of many I suitable means.

A ma netic pole-piece is provided for each pole of t e magnetic source and each of these pole-pieces is made up of two rectangular blocks 23and 24. The two blocks for each pole piece, as shown in Fig. 3, are arranged side by side and are recessed to receive be tween them the upper end of a core 25. The latter, as indicated in Fig. 4, is built up of laminations which are drawn together by, and held to, the mating pair of blocks by a single screw 26 (Fig. 3). The latter asses through the back frame 15, throng the block 24 and core 25 and threads into the block 23. The screw 26 serves to draw the blocks together, thereby clamping the laminations of core 25 and also securing these parts to the back frame 15. The clips 21, above described, are secured to their respective ole-pieces by screws 27 which pass 15p war ly through the latter and thread into the lower part of the clips, there being two screws for each clip, as indicated in Fig. 3. The two pole-pieces may be further tied to gether by a bar 28, of non-magnetic material, which connects the spaced blocks 23 and is securedthereto by screws 29.

The two cores 25 extend downwardly from their pole-pieces in parallel relation, one on each side of the guide-rod 19, and terminate at a short distance below the lower edge of frame 15. Near their lower ends, the laminations of the cores are clamped together and connected to the frame 15 in' a manner similar to that above described except that two

members

30 and 31, of non-magnetic material, suflice for both cores. Two screws 32, passing. through frame 15, member 30 and the cores 25, thread into member 31 and serve to draw the members together and hold them to the frame.

U on each core 2", and between the points at w ich it is clam ed, are provided two

coils

33 and 34 arranged one upon the other. The inner coils 33 are provided for a choking function, either to retard the building up, or the diminution of, magnetic flux in cores 25. The outer coils 34 constitute the enerating winding. The electrical connections of these coils are shown in Fig. 5. The coils 34 are usually, although not necessarily, con nected in series, as by a wire 35 joining one terminal of each coil. The other terminals of generating winding, constituted by the connected coils, are the service terminals. Customarily, one terminal is grounded, as by a wire 36, tothe frame of the magneto and the other extends to the ignition system, as

indicated by the wire 37 extending to a spark-plug s.

The two coils 33 are also usually, although not necessarily, connected in series, as by a wire 38 joining one terminal of each coil. The other terminals of the choke-winding, afforded by the connected coils 34, are connected to relatively-movable breaker-points and 40 and a condenser 41 is bridged across these terminals in the usual manner. Usually, as shown, one terminal of one coil 33 is grounded, as by a wire 42, to the frame of \the machine, whereby to conveniently connect with the movable breaker-point 40, which, as will appear, is in constant metallic connection with the frame, and one side of the condenser 41 is similarly grounded. The corresponding terminal of the other coil 33 is connected, as by a wire 43, to the stationary breaker-point 39 and the other side of the condenser 41. The latter is convenientlylocated beneath the magnets 20 and between the clips 21, where it is sup ported by resting upon the blocks 23 and 24 (Figs. 2 and 3).

The magnetic circuitwill be readily understood from Fig. 5. The poles of the magnetic source, extended by the cores 25 to admit the

windings

33 and 34 are periodically connected and disconnected by an armature 45, thereby providing for a mag netic circuit of alternately low and high reluctance through the windings.

The armature 45, as best shown in Fig. 3, may be made up of laminations in the usual manner, although this is not necessarily essential. The armature isfixcd to a guide sleeve 46 and the laminations are spread apart at the center of the armature to permit the sleeve to pass therethrough. Bolts 47 (Fig. 2) located on opposite sides of sleeve 46, pass through the armature and serveto clamp the laminations thereof together as well as to bind them to the sleeve. Slidable within sleeve 46, and upon the guide-rod 19, is a second sleeve 48 upon the lower end of which is threaded a collar 49 and below the latter a fork 50. The eccentric f is provided with a suitable strap 51 to which is fixed a stud 52 and adptstably threaded on stud 52, and held in its various positions thereon by a lock-nut 53, is a member 54 which fits within fork and is pivotally connected thereto by a pin Both sleeves 46 and 48 have longitudinal slots 56 and 57 respectively. extending from their upper ends downwardly a substantial dis and into the casing.

tance. These slots function as keyways, both being arranged to cooperate with a single key 58 in rod 19, which key permits the desired vertical sliding movements of the sleeves and yet holds them in the desired angular relation. More particularly, it keeps the armature 45 properly positioned with respectto cores 25.

Preferably, although not necessarily according to all features of the invention, the armature 45 is not lifted directly by the cam-follower or lifting sleeve 48 butrather through the intermediary of resilient means. As shown, such means consist of a coilspring 59 which acts between the collar 49 and the flanged lower end of the sleeve 46.

For the purpose of moving the armature rapidly away from its poles, a drivingspring 60 is provided and the force exerted by this spring on the armature, when the latter is positioned as in Fig. 3, is less than the force of magnetic attraction on the armature, and as will later appear may be at such time reduced to, or substantially to Zero. The spring (30, as shown, is a coil spring which encircles the sleeves 46 and 48 and acts between a spring-seat 61, which abuts the lower face of the boss 17 on frame 15, and a cup-shaped spring-seat 62 which slips over sleeve 46 and acts against the upper face of armature 45. As shown, a plate 63, also loosely fitting on sleeve 46, is interposed between seat 62 and the armature and projects laterally therefrom for connection to the interrupter mechanism to be later described. As shown in Fig. 4, the members 80 and 31 are recessed centrally at 64 to receive and closely fit the peripheral wall of the cup-shaped spring-seat 62, and such wall is of sufiicient longitudinal extent so that its open upper end never passes out of the lower end of opening 64, thus preventing the ingress oidust and dirt into the magneto through the bottom closure afforded by the

members

30 and 31.

The interrupter includes a cylindrical casing 65, which is driven into an opening in the member 31 and thereby held stationarily to the frame structure already described. This casing extends upwardly in parallelism withthe line of travel of the armature and is located at the front of the magneto for convenient access and inspection. At the upper end of the casing 65 is a bridge 66 in which the stationary breaker-point 39 is adjustably mounted and from which it is suitably insulated, all as indicated in Fig. 3. The movable breaker-point 40 is carried on the upper end of a relatively long cylinder 67 which closely fits in and is guided by the casing 65. The lower end of cylinder 67 is closed. except for a central opening to receive a rod 68 which passes loosely therethrough The upper end of rod 68 carries a head 69 and between this head and the closed upper end of casing 67 is a spring 70, through the intermediary of which the cylinder 67 is lifted from the rod 68. The latter, in its descending movement, lowers cylinder 67 by reason of the abutment of head 69 with closed lower end of the cylinder. The lower end of rod 68 is threaded into and thereby adjustably secured to, the projecting portion of the plate 63 above described. A screw-driver slot is provided in the lower end of rod 68, whereby it may be conveniently turned for adjust ment and a lock-nut 71 is provided on the rod to prevent change of the adjustment.

It is to be noted that the movable breakerpoint 40 can yield relatively to its actuating rod (38. Such yield is desirable for several reasons. First, the travel of rod 68 need not be the same as the travel of point 40. Second, it is desirable that the latter be less than that of rod 68 to compress the spring after engagement of the

points

39 and 40, so that the latter willbe held firmly pressed together even after considerable wear. Third, it is desired, according to one feature of the invention, to be able to open the breaker-points after they have been closed by upward movement of the armature and while the latter is seated on its cores. For this purpose, a lever 72 is provided which is pivoted intermediate its ends at 73 to a bracket H fixed to boss 17 by the screw 18 described. Lever 72 may consist simply of a member bent into the shape of a hairpin (Fig. 10) and passed through a block 75 of fibre below the pivot-pin 73. by means of which the block is supported in the forked lower end of bracket H. The curved end of lever 72 lies in the path of the cylinder 67 of the interrupter mechanism and the other, and laterally-spaced, ends straddle guide-rod 19 and lie in the path of the upper end of sleeve 48. This sleeve has a greater travel than the armature and, after the latter has been seated, continues to move upwardly and in such movement engages and lifts the inner end of lever 72, thereby depressing its outer end and lowering cylinder 67 with the breakei point 40 carried thereby. On a reverse movement the sleeve 48 moves downwardly sufiiciently to release lever 72 and allow the breakerpoints to close previous to disengagement of the armature from its poles.

Another advantageous way of constructing the lever 72 is shown in Fig. '12. the difference being that instead of a single hairpin shaped member, as shown in Fig. 10, two straight members 72 are passed through block 75 in converging relation, the converging ends lying at the sides of the breaker point 40 rather than at the back thereof. \Vith this arrangement, the casing 65 of the interrupter mechanism is turned 90 from the position illustrated in Fig. 8.

The means for breaking the magnetic hold upon armature 45, or, as it may be termed, tripping it so as to allow spring 60 to act and drive it rapidly downward, may be variously constructed as desired, although,.of course, it will be controlled from the moving parts of the engine, as from the camshaft d for example. For the purpose of avoiding unnecessary multiplication of parts, we prefer to control and actuate the tripping means from the mechanism by which the armature is deposited on the cores 25.

This result may be accomplished in the following simple manner. A collar 76 is slipped over sleeve 46 prior to assembly of the armature thereon and is held between the latter and the flanged end of sleeve 46. This collar 76, as shown, is cupped downwardly and then bent outwardly to afford a circular flange 77, which is spaced from the armature. A second collar 78 is adjustably connected t the collar 49, as by the screwthread connection shown,vand extends upwardly therefrom, terminating with a cir cular flange 79 above, but located in the path of flan e 77. Thus, after the sleeve 48 has descen ed a predetermined distance. which may be varied by turning collar 78, the flanges 79 and 77 will be enga ed and armature will be pulled away rom its poles, breaking the, magnetic hold on the armature and allowing spring to drive it rapidly downward. It is also to be noted that thesemembers 7 6 and 78 constitute telescoping housings for spring 59 to conceal and protect the latter and prevent to a considerable degree the ingress of dust and dirt.

Another way of trip ing the armature is shown in Fig. 11. there shown, the guide rod 19 has been replaced by a guide sleeve 19, and a lifting rod 48 rather than a lifting sleeve, slides inside of it. The guide sleeve is slotted longitudinally at opposite-points in its peripheral wall, as indicated at 81 and a in 82, driven through the lifting rod 48, has projecting-end portions which ride in these slots and extend beyond the guide sleeve 19'. Loosely mounted on the latter beneath pin 82 is a cupped washer 83 which forms a seat for the drive spring 60. The latter, as shown, is fully expanded and under no stress but is adapted to be compressed, and thus stressed, by the descent of the rod 48. After the latter has moved downwardly sufficiently to place spring 60 under the. desired stress, washer 8-3 abuts the upper end of the armature sleeve 46 and pulls the armature 45 away from its cores, allowing the spring, previously stressed as described, to drive the armature rapidly downward.

In connection with this tripping arrangement, means are provided for varying the time in the stroke of member 48' at which n the arrangementthe abutment forming washer 83 will engage sleeve 46. This means consists of an eccentrlc connection between fork 50 and member 54 whereby the sleeve 46 may be drawn toward or moved away from the eccentric strap 51. Thus, in place of the pivot pin 55, heretofore described, a pin is provided having'concentric end portions 85 mounted to turn in the arms of fork 50 and an intermediate eccentric portion 86 to fit into theeye in member 54. A handle 87 is fixed to one of the portions 85 for convenience in turning this pin and effecting the adjustment described. The eccentric 86 may be turned to move rod 48' upwardly a sufficient distance so that washer 81 cannot abut sleeve 46 at any point in its stroke. Thus, the armature 45 may remain on its poles during reciprocation of rod 48, whenever desired.

. Various other means may be devised for tripping the armature in the manner described and the invention, in its broader aspects, is independent of the particular means described. The particular tri ping means disclosed are, in a measure, pre erred on account of their simplicity and convenient adjustability.

The magneto maybe suitably encased, as indicated in Fig. 1, by housings 80 and 81 which enclose all parts above the members 30.

The operation of the magneto, and more especiall the movements of the armature with which the broad features of the invention are concerned, will now be described. Assumin that the cam-follower sleeve 48 is in its Tower position and that the eccentric f is rotating, the sleeve 48 will be raised progressively and relatively gradually to deposit the armature on its poles (comprising the lower ends of cores 25). The raising of the armature, however, is preferably not directly accomplished by sleeve 48, for it is usually desired to seat the armature on its poles as quietly as possible. Therefore, the cam follower transmits its lifting force to armature 45 through the intermediary of the spring 59. ,Opposing the action of the latter is the drive-spring 60, and the armature is thus carried upward between two forces, which naturally seek a balance. The upward movement of the armature is therefore not directly proportional to the movement of the cam-follower, for the latter encounters increasing resistance as it. moves upwardly by the compression of spring 60, and as the latter compresses the spring 59 must compress to balance it. Therefore, the upward movement of the armature, which-i.

ma be initially nearly as fast as the camfol ower, soon becomes slower and slower as it approaches the poles. This articuthe armature, a though lar mode of liftin desirable and pre erred because it permits extended wear. "affords a means for opening the breaker 'le seating of the is not inve In the above description of the forces acting on armature 45 during its upward travel, no consideration was given to the upward force which would normally tend to draw the armature to its poles with a sharp noise, for as the armature nears the latter the magnetic pull would increase very rapidly, and this rapidly-increasing force added to that or" spring 59 would tend to defeat the object sought for, viz, the depositing of the armature on the come as quietly as possible. However, the effect of magnetic pull is substantially reduced so as to be a practically negligible factor in the described operation. This is accomplished by the closing of the choke-coil circuit during the latter part of the upward flight of the armature. The breaker-points, controlling the opening and closing of this choke-coil circuit, are, when the armature is in its lowest position (Fig. 6 open as shown in Fig. 6. As the armature nears its poles to a position such, for exam le, as is indicated in Fig. 7, it has move sutiiciently to carry the breaker-point 40 into engagement with the fixed breakerpoint 39, as indicated in Fig. 7, thus closing the circuit in which the choke-coils are located. On continued movement of the armature, spring 70 compresses to take care of the over-travel of rod 68, and the points remain closed until after the armature has been seated on its poles. These coils, when in a closed electrical circuit, oppose a change of flu in the magnetic circuit, and in this instance they oppose the building up of the f ux in cores 25 and consequently there will not be immediately a magnetic pull on the armature of anything like the usual stren th. The force, due to magnetic pull, is en stantially reduced over that which would otherwise eriist if the choke-coil circuit were left open.

After the armature has been seated on its poles,..the cam-follower continues its upward travel, the spring 59 by its further compression, permitting this action. This ovei'travel of the cam-follower is important since it insures that the armature will continue to be seated on its poles even after It is also impoitant as it u armature on its poles, essential to the broad features of the points after the armature has come to rest on its poles and is no'longer available to actuate them. Continued travel of the camfollower opens the hieaker-points as illustrated in Figs. 3 and 9, thus allowing the flux to build up rapidly in the now closed magnetic circuit.

The. ea-m follower having reached the upper end of its stroke, will in the picsent case, immediately commence to descend but the armature 25 will remain on its poles bccause the force of magnetic attraction acting on the armature is at that time superior to that of spring 60. The fiist result of the downward movement of the cam-follower is an expansion of spring 59 and a release of lever 72, whereby the breaker-points are closed. The closing of the latter occurs before the engagement of the. flanges 72 and 79 and thus before the armature leaves its poles. This condition is illustrated in Figs. 7 and 7*. Thus, the choke-coils are again brought into play on the magnetic circuit, but for a ditlerent purpose, viz, to oppose any sudden change in magnetic flux when the armature. leaves its poles.

T he disengagement of the armature from its poles is not accomplished by the sudden application of a substantial initial force. On the contrary, when in the descent. of the cam-follower, the force opposing the driving action of spring 60,-in this instance that due to magnetic attraction,becomes slightly less than that of spring 60, the armature will begin to move but naturally slowly in its initial infinitesimal step of downward movement because the driving force is infinitesimal. The lessening of the force of magnetic attraction is effected by bringing into play a force which supplements that of the drive-spring. That is, the flange 79 will eventually engage flange 77 and a down and pull will be applied to the armature. This supplementary force is, however, applied progessively until the. combined forces of spring 60 and the tripping mechanism just overbalance that due to magnetic attraction and supply a differential of force to more the armature. The supplementary force exerted by the tripping mechanism is, how ei e'r, of very short duration and hence this mechanism has been said to trip the armature in. order to allow the spring 60 to act. Practically, the instant the armature is separated from its poles by a very slight air gap, the force of magnetic attraction has been so very greatly diminished that spring 60 is then superior to it. Continued increase in the air gap diminishes the force exerted on the armature by magnetic attraction still more rapidly. On doubling the air gap, the force 18 at the very least quartered, and so on. Thus, once the armature is started from its poles, no matter how slowly, by the very smallest differential of force, its subsequent movementis rapidly accelerated on accountof the exceedingly rapid diminution of the resisting force. The practical result is that a high armature speed is obtained after the armature has moved away from its poles a certain distance, and at the point of maximum speed, or as nearly thereto as it can be arranged, the breaker-points open. The cliokin ef feet on the magnetic circuit having on i starting the armature from its cores, they thus done away with, there results a very ra id change of flux in this circuit, thereby in ucing a high voltage in the generating winding. Thus, by the expedient of the breaker points and choke-coil windin which may be likened to a valve for contro ling the flux in the magnetic circuit, it is possible to hold the flux in the latter until the armature gets under way and attains a sutlicient speed. Otherwise, the change in flux would be relatively gradual because it would depend entirely on the speed of the armature in the initial stages of its downward flight.

To complete the description of operation, it should be noted that the spring 59 has still another function which is to yieldingly and uietly arrest the armature in its downward ight. After the breaker-points have opened for the purpose of releasing the flux in the magnetic circuit, the driving force of spring 60, by its expansion, weakens and in addition encounters increasing opposition by reason of spring 59 and the forces due to these two elements seek and find their balance and thus arrest the armature in the (le sired quiet manner.

The operation of the magneto shown in Fig. 11 is essentially like that already described. The springs 59 and 60, however, do not in this instance cooperate in the manner above-described but the armature 45 moves proportionately with the lifting rod 48 until it engages its poles. The cushioning effect, above described, is not so essential to a gentle seating of the armature on its poles, where the force of magnetic attraction is, as here, substantially diminished. After the seating of the armature, the rod 48 continues its upward movement, relaxes the tension of spring 60,-entirely if desired, and later on its downward movement laces this spring under stress and thereaiter trips the armature. i

The cooperating flanges 77 and 7 9, or the

members

83 and 46, either of which break the magnetic hold on the armature, are, as above stated, essentially a tripping means in that they act only for an instant and control the time of downward flight of the armature. Although they contribute to spring 60 in do not continue to act, for the expansion of the s ring a ainst the very rapidly diminishing orce o magnetic attraction moves the armature much more rapidly than it could be moved by the tri ping means and the flanges 77 and 79, or

t ie members

83 and 46, soonseparate. Hence, such means are not the means used to obtain high armature speed but rather are used to control the time when the armature-driving means is allowed to act. a

The importance of the tripping means in effecting variations in timing of currents generated will be readily apparent. Such variations are effected simply by turning collar 78, or handle 87 to alter the time at which the flanges 77 and 79 or the

members

83 and 46, will engage. No new setting of the ec' centric f on its shaft is required.

The closing of the breaker-points and the holding of them closed until the armature is seated, while important and preferred for the reasons outlined, is obviously not concerned in any way with the downward flight of the armature. Even on the upward flight of the armature, the timing of the extra closing and opening may be changed as occasion requires to effect other results.

In conclusion, it may be pointed out that the necessary speed of the armature is really obtained by fully utilizing the factor of the rapidly diminishing force of magnetic pull by the creation and the increase of an air gap. This factor may be termed magnetic retraction as distinguished from magnetic attraction and is the factor relied upon here to obtain armature speed, as distinguished from the hammer blow or the siiibstautial, and instantaneously applied, initial force heretofore used to produce an initial high speed. Inasmuch as the flux can be held by the choke-coils for an interval sufficient to accelerate the armature to the desired speed, initial speed becomes unnecessary.

Although the invention has been described herein with considerable particularity in order to make clear to those skilled in the art a preferred means of making use of it, it is to be understood that the invention is not limited to the details illustrated and described. except as they are included in the following claims.

What we claim is:

1. In a magneto, of the type wherein an armature moves into andout of engagement with magnetic poles to vary the reluctance of a magneti circuit and a generating windingis associated with said circuit .inwhich currents are induced by the variation of flux therein; mechanism for seating the armature on its poles to which" it is then held by magnetic attraction, driving means arranged to act on the armature in opposition to magnetic attraction, and means for diminishing the force of magnetic attraction on the armature to allow the driving means to move the latter.

2. In a magneto, of the type wherein an armature moves into and out of engagement with magnetic poles to vary the reluctance of a magnetic circuit and a generating winding is associated with said circuit in which currents are induced by the variation of flux therein; mechanism for seating the opposite direction, and relatively slow-actmeans for starting the armature from its poles sufficiently to allow the driving means to move the armature, the driving means being then effective to move the armature at rapidly increasing speed due to the rapidly dii'ninishing force of magnetic attraction.

3. in a magneto, of the type wherein an armature moves into and out of engagement with magnetic poles to vary the reluctance of magnetic circuit and a generating winding is associated with said circuit in which currents are induced by the variation of fill therein; mechanism for seating the armature on its poles to which it is then held by magnetic attraction, driving means of less strength than the force of magnetic attraction for moving the armature in the opposite direction, and means for removing the armature from its poles suiiicientiy to permit the dri'ing means to act due to diminution of the force of magnetic attraction on the armature.

4-. In a magneto, of the type iv-herein an armature moves into and out of engagement with magnetic poles to vary the reluctance of a magnetic circuit and. a generating wind is associated with said circuit in which currents are induced by the variation of Finn therein: mechanism for moving the armature into engagement with its poles to vmich it is then held by magnetic attraction, means acting on the armature in opposition to the force of magnetic attraction and evening a pressure less than said force, means for risengaging the armature from its poles, whereby the force due to magnetic attraction is lessened by the estahlishment of an air gap and the first-named means is rendered effective to move the armature.

In a magneto, of the type wherein an armature moves into and out of engagement vith magnetic poles to vary the reluctance of magnetic circuit and a generating winding is associated with said circuit in which currents are induced by the variation of flux therein; mechanism for seating the (tuna tnre on its poles to which it is then held by magnetic at action. driving means arranged to acton the armature in opposition to magnetic attraction, means for diminishing the force of magnetic attraction on the armature to allow the driving means to move the latter, a closed circuit choke-Winding associated with the magnetic circuit, and means to open said winding after the armature has moved away from the poles.

6. In a magneto. of the type wherein an armature moves into and out of engagement With magnetic poles to vary the reluctance of a magnetic circuit and a generating winding is associated with said circuit in which currents are induced by the variation of flu}; therein; mechanism for seating the armature on its poles to which it is then held by magnetic attraction, driving means arranged to act on the armature in opposition to magnetic attraction, means for diminishing the force of magnetic attraction on the armature to allow the driving means to move the latter, a choke-winding associated with the magnetic circuit and arranged in an electrical circuit which can be opened and closed; and means for closing said circuit as the armature approaches its poles, opening it after the armature is seated on its poles, closing it before the armature leaves its poles and opening it after the armature has moved away from its poles.

7. In a magneto, of the type in which an armature is periodically moved into and held in contact with magnetic poles; driving means arranged to act on the armature 0ppositely from its supporting force, means for changing the relation of the o posing forces acting on the armature for t 1e purpose of moving the latter away from its poles, and means for varying the time at which said change is effected, said second named means efiecting a regressive change in the first instance an creating only a differential of force to start the armature away from its poles.

8. In a magneto, wherein the armature is held by magnetic attraction to its poles, driving means for moving the armature rapidly away from its poles after it has been started therefrom, and means periodically operable to start the armature away from its poles.

9. In a magneto wherein the armature is held to its poles by magnetic attract-ion, resilient driving means for the armature substantially unstressed when the armature is in Contact with its poles and means periodically operable from a moving part of an engine to place the driving means under the desired stress and start the armature in its flight away from the poles by an inelastic transmission of force from mid moving part.

10. In a magneto of the type wherein an armature is moved into and out of contact with magnetic poles, resilient means tending to move the armature away from its poles but exerting insufficient force to overcome the force of magnetic attraction between the armature and its poles, and mechanism operable from a moving part of the engine and periodically effective through an inelastic transmission of force from said moving part to overcome the magnetic hold on the armature and permit said resilient means toact.

11. In a magneto of the type wherein an arn'iature is moved into and out of contact with magnetic poles, resilient means tending to move the armature away from its poles but exerting insnflicient force to overcome the force of magnetic attraction between the armature and its poles, and mechanism operable from a moving part of the engine and periodically effective to first increase the stress in said resilient means and then break the magnetic hold on the armature by an inelastic transmission of force from said moving part.

12. In a magneto, of the type wherein an armature moves into and out of engagement with magnetic poles to vary the reluctance of a magnetic circuit and a generating winding is associated with said circuit in which currents are induced by the variation of flux therein; a reciprocable member slidable relatively to the armature, elastic means through which said member acts on one' stroke to move the armature into contact with its poles and by which continued movement of the member on the same stroke is permitted after the armature abuts its poles, and means carried by said member operable at apredetermined point in its return stroke to disengage the armature from its poles. g

13. In a magneto, of the type wherein an armature moves into and out of engagement with magnetic poles to vary the reluctance of a magnetic circuit and a generating winding is associated with said circuit in which currents are induced b the variations of flux therein; a reciprocab e member slidable relatively to the armature, elastic means through which said member acts on one stroke to move the armature into contact with its poles and by which continued movement of the member on the same stroke is permitted after the armature abuts its poles, and means carried bysaid member operable at a redetermined point in its return stroke to disengage the armature from its poles,

said means being adjustable to vary the time of departure of the armature from its oles.

14. In a magneto, of the type whereman armature is moved into and out of contact with magnetic poles, a reciprocable member effective on one stroke to move the armature into contact with its poles and capable of moving on the other stroke without moving the armature, and means on said member efiective at a. redetermined point in the lad: named stro 0 thereof to move the armature away from its poles.

15. In a magneto, of the type wherein an armature is moved into and out of contact with ma etic poles, a reciprocable member capa. 1e of pushing but not of pulling the armature and operable on one stroke to push the armature against its Ice, and means connected with said mem r to en-. gage the armature after said member. has moved apredetermined distance on its return stroke and apply a. pull on the armature.

16. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic poles, a reciprocable member capable of pushing but not of pulling the armature and operable on one stroke to push the armature against its poles, and means adjustably connected with said member to engage the armature after said member has moved a predetermined distance on its return stroke and apply a pull on the armature.

17. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic poles, a reciprocable member slidable through the armature and provided with a shoulder, a spring interposed between said shoulder and the armature, cooperating devices one movable with the armature and the other movable with said member arranged to engage at a predetermined point in one stroke of saidmemher to permit the latter to move the armature in a direction opposite to that in which it is moved through the intermediary of said s ring.

18. n a magneto, of the t pe wherein an armature is moved into an out of contact with magnetic poles, a sleeve, fixed to the armature, a lifting member including a portion slidable in the sleeve and having a shoulder, a sprin encircling the lifting member and acting etween said shoulder and armature to transmit motion in one direction to the latter from the liftin member, coopcrating devices one oarrie by said sleeve and one by said member, and means for reciprocating the lifting member, said devices each having a art arranged in the path of the "other an en ageable after the lifting member has moved a predetermined distance in the other direction to move the armature.

19. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic poles, a member movable with the armature, a reciprocable member slidable relatively thereto, an abutment provided on the second member by which the other member may be moved in one direction, and an abutment mounted on one of said members to engage the other when the second member is moved in the other direction.

20. In a magneto, wherein the armature is held to its poles by magnetic attraction, resilient driving means for the armature substantially unstressed when the armature is in contact with its poles and means periodically operable to place the driving means under stress and then start the armature from its poles.

, 21. Ina magneto, wherein the armature I is held to its poles by magnetic attraction,

continuously reciprocable mechanism operable onone stroke to periodically cause the armature to be deposited on its; poles, and

free to move a predetermined distance on its return stroke without moving the armature, substantially inelastic means protitled on the armature and said mechanism adapted to engage after said mechanism has moved said predetermined distance and start the armature away from its tploles, and means for varying the time in e return stroke at which the armature is started from its poles.

22. In a magneto, wherein the armature is held to its poles by magnetic attraction, continuously reciprocable mechanism operable on one stroke to periodically cause the armature to be deposited on its poles, and free to move a predetermined distance on its return stroke without moving the armature, substantially inelastic means rovided on the armature and said mechanism adapted to engage after said mechanism has moved said predetermined distance and start the armature away from its poles, and means for adjusting said mechanism to vary the time when the armature is started from its poles.

23. In a magneto, wherein the armature is held to its poles by magnetic attraction, continuously reciprocable mechanism operable on one stroke to periodicaliy cause the armature to be deposited on its poles, and after a. predetermined movement on its return troke to start the armature away from its ties, and m ans for adjusting said mecha- 'sm to vary the time when the armature s started from its poles, said last-named means capable of being varied so that the armature may remain on its poles during reciprocation of said mechanism when desired.

23%. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic poles, means to deposit the armature on its poles, resilient means for moving the armature away from its poles and exerting less force on the armature when the latter is in contact with its poles than that due to magnetic attraction, and means operable to increase the stress in said resiiient means.

In magneto, of the type wherein an ;store is moved into and out of contact with 510 p ice, resilient means for moving the armature away from its poles, mechanism movable in one direction to deosit the armature on its poles and diminlSl'l the stress on said resilient means so that the armature may be held to its poles by magnetic attraction, said mechanism when moved in the opposite direction arranged to stress said resilient means to the desired degree.

26. In a magneto, of the type wherein an armature is moved into and out of contact with magnetic poles, a reciprocable member effective on one stroke to move the armature into contact with its poles and capable of moving on the return stroke without moving the armature, resilient means for moving the armature on the return stroke, and means movable with said member operable on its return stroke to first place said resilient means under the desired stress and then to detach the armature from its poles to allow the stressed resilient means to move the armature.

27. In a magneto, resilient means for moving the armature away from its poles, an abutment between which and the armature said means is interposed and against which said means acts to move the armature, and means for moving said abutment.

28. In a magneto, resilient means for moving the armature away from its poles, an abutment between which and the armature said means is interposed and against which said means acts to move the armature, and means for moving said abutment in the direction of expansion of said means during said movement of the armature.

29. In a ma eto, resilient, means periodically expansib e to move the armature away from its poles, and mechanism operable during the expansion of the first named means and supplementary to the diminution in the force of ma etic attraction between the armature an its poles to compensate for the natural diminution in stress of said spring.

In testimony whereof we have ailixed our signatures.

PHELPS BROWN. HAROLD H. CLARK.