US1050739A - Starter for explosive-engines. - Google Patents

Description

R. O. HULL.

STARTER FOR EXPLOSIVE ENGINES.

APPLICATION FILED AUG.26,1912.

Patented J an. 14, 1913 1,050,739. 4 SHEETS-SHEET 1.

FILE I I 44 Z3 21 b o A M 7 4 k 4? 5 4a 1 20 H 50 i! 9 o O W V g b L r Light 33 2 we -n I I :1 1 i 1 0 13 16 :H

32. L f J zlflVENTOR 2 I I av R. C. HULL.

STARTER FOR EXPLOSIVE ENGINES.

APPLICATION FILED AUGDZG; 1912.

Patented Jan. 14, 1913.

4 SHEETS-SHEET 2.

INVENTOR f; ATTORNEY BY W16 7 V WW4 R. C. HULL.

STARTER POE EXPLOSIVE ENGINES.

APPLICATION FILED AUG,26, 1912.

1,050,739. Patented Jan. 14,1913.

4 SHEETSSHEET 3.

4 A TTORNE Y t v M INVENTOR M 5 R. G. HULL.

STARTER FOR EXPLOSIVB mamas.

I APPLICATION FILED AUG.26, 1912. 1,050,739, Patented Jan. 14, 1913.

4 SHEETS-SHEET 4.

FIG. 7-

II 43 59 47 13 4 31 29 W x J? 28 97 w n I k FIG. 8-

W W 2am BY I L UNITED sTAr s IZATENT OFFICE.

STARTER FOB EXPLOSIVE-ENGINES.

Specification of Letters Patent.

Patented Jan. 14, 1913.

Application. filed August 26, 1912. Serial No. 716,992.

T 0 all whom it may concern I Be it known that I, ROBERT C. HULL, a citizen of the United States, residin in the cit of Philadelphia, county of P iladelphia, and State of Pennsylvania, have invented a new and useful Starter for Explosive-Engines, of which the following is a specification.

My invention relates to a starter for explosive engines, such as gas engines, gasolene engines, and the like, which are not self starting but require to be cranked, or turned over to cause a sucking into the cylinder or cylinders of an explosive mixture and the compression thereof; this mixture when ignited by the. usual ignition means forcing the piston or pistons forward to deliver to the crank shaft the initial impulses as a result of which the engine itself draws or sucks in and compresses the explosive mixture automatically causing automatic continued operation of the engine.

My invention relates particularly to electromagnetic or electro-dynamic means for starting an explosive engine, the electro magnetic or electro-dynamic means converting electrical energy into mechanical energy for cranking or turning over the explosive engine for the purposes above doscribed;

As early as the year 1886, I believe, it was proposed to impart the initial movement to the piston or pistons of an explosive engine by an electric motor, comprising relatively rotating armature and field magnet, the rotatable member of the motor, as the armature, being directly secured upon the engine crank shaft or suitably geared thereto for engine starting purposes. And even at the present time, particularly with regard to the explosive engines employed on automobiles or like motor vehicles, such an electric motor is resorted to for engine starting purposes, a suitable source of electric energy being provided to drive the motor. Such an electric motor is well understood to comprise an armature having the usual commutator with brushes bearing thereon, the resultant relative movement. between brushes and commutator causing the progressive shifting. of the ma etic poles of the armature, produced by t e current in its winding, such progression of the magnetic poles tak- Hi arina iure itself; And it is further characace with respect to the body of the tcristic ofi such an electric motor that the relative movement between the brushes and commutator corresponds precisely with the relative movement between armature and field magnet, because the commutator is in fixed relation with the armature and the brushes in fixed relation with respect to the field magnet. From such an electric motor and all other forms of starters my invention sharply'contrasted, in that I employ tlurotor of my electro dynamic means a member which exhibits magnetic poles which remain substantially fixed with re spect to the body of the rotor, and such same; and as stator I employ a. magnetic system in which the magnetic poles progress with respect to the body of the stator. And my invention is further contrasted in that the switching or commutating means for ,poles in the stator may be detached or dislmembcred' from the electro-dynamicdevice and removed to any suitable point, as upon the dashboard of an automobile, where, in operation, such commutating or switching means may be operated solely at the will oi the driver and are not necessarily driven as in an ordinary electric motor in perfectly definite relation with respect to the moving element of the motor.

In one of its aspects my invention may be viewed as employing an electric motor dismembered to the extent that the moving part of the commutator mechanism does not necessarily or at all times rotate in fixed relation with and is not drivenby the rotating element of the motor but may be located at a distance from the motor at a point where the control is to be exercised and there moved at the will of the operator to cause relative movement between the rotating and stationary elements of the motor, without as in the case of an ordinary mo- 'tor movement of the movable part of the commutator mechanism by the rotating element of the electro-dynamic means.

In another of itsv aspects my invention may be viewed as employing an electric motor. dismembered to the extent that the moving part of the commutator mechanism, whil'ejt may rotate in fixed relation and be driven by the rotating element of the motor, is not necwsarily always mechanically and electrically in connection with the fixed part magnetic poles therefore rotate with the causing the progression of the magnetic of the commutator mechanism, for, by my invention, these two parts may be mechanically and electrically connected at the will of the operator.

A further feature of my invention resides in the fact that the winding of the rotor is traversed by a relatively heavy or large current admitted to such winding through collectors and slip rings whose only function is to maintain electrical communication and not to commutate, with the result that troubles attendant upon the use of a com mutator and brushes for heavy currents forming a part of the armature of an ordinary electric motor are not encountered; with a relatively small current in the stator, this being the current which is controlled and commutated.

As is well understood with respect to an explosive engine, the negative torque offered by the same during the cranking or "turning over for starting purposes, is not uniform, but passes through a more or less sharply defined maximum and falls away again to lesser values. By my invention,

though I do not limit myself thereto. I may,

employ electro-dynamic means which will produce a non-uniform torque having well defined maximum points. And these points of max num positive torque shall preferably occur substantially simultaneously with the maximum negative torque exerted in op position by the engine. The number of points of maximum positive torque developed by the electro-dynamic means may be greater than the number of points of maximum negative torque exerted in opposition by the engine, but the former points may always be a multiple of the latter points so that in all cases one of the former points shall occur substantially simultaneously with one of the latter points. And i prefer that the'positive torque developed by the electrddynamic means shall always be at least as great as the negative torque of the engine exerted simultaneously therewith.

My invention resides in the apparatus for starting an explosive engine herein described.

My invention resides in the features here ina'lter described and claimed.

For an illustration of some of the forms my invention may take, but Without limiting my invention thereto, reference is to be had to the accompanying drawings, in which:

Figure 1 is a longitudinal cross-sectional view. some parts in elevation, through a part of an automobile or similar motor vehicle. Fig. 2 is a diagrammatic view illustrating the circuits of and means for control of one form of electro-dynamic starter. Fig. 3 is a diagrammatic view of a modified form of'startcr and its control circuits. Fig. 4 is a diagrammatic view ofa further modification of the electro-dynamic starter and its control circuits. Fig. 5 is a graphic representation of the torque curve of a single cylinder of an explosive engine, as

, a four cylinder engine, and a torque curve of an electro-dynamic starter therefor. Fig. 6 is a graphicrepresentation of similar torque curves of a six cylinder engine and of a starter therefor. Fig. 7 is a diagrammatic view of a modified form of starter system. Fig. 8 is a fragmentary view illustrating structure of the commutating mechanism of Fig. 7.

Referring to Fig. 1, the frame or chassis 1 of an automobile or like vehicle has secured thereto the explosive engine E here illustrated, by way of example merely, as having four cylinders 2, 3, 4, and 5, the engine E being inclosed in the hood 6 extending from the dash board 7 to the radiator 8. -Upon the shaft 9 of the engine is secured the fly-Wheel 10, which, however, may be omitted if desired. Secured upon the shaft 9 is the rotor element 11 of the elcctro-dynamic starter, the same being surrounded by the stator member 12 provided with lugs 13 resting upon and secured to the frame 1. Or these lugs 13 may rest upon and be secured to or integral with the engine bed, so that the engine and electrodynamic starter may he removed as a unit. Between the engine shaft 9 and the driving shaft 14, leading to the running gear, not shown, may intervene the clutch comprising the driving member 15 and the driven member 16 operated by any suitable means as the lever l7 near the, seal l8 of the driver. near which are disposed also the usual steering Wheel 19 and other (unil'fil members 20 and 21. Upon the dash board 7. or at any other suitable point within reach of the driver. are disposed the switch 2'2 and the switching or eommutaling apparatus 2 inclosed within the casing 24 and disposed upon the base 23, the crank 26 disposed out side of the casing 2t for operation by the driver as hereina 'lcr described. At any suit able placeon the automobile or .tl1l(l0 is mounted any suitable source of cos-sa nt such as a storage battery 97. Referring" now to Fig. 2 one arrangement of my electro-dv numic starter and its control are illustrated Here the rotor ll, secured upon the engine shaft 9, as by a spider r other suitable means, not shown, compris s a core ll of iron or other suitable magnetizablc material upon which is disposed a winding or conductor 28 with which connection is made through conductor 29 permanently connected to the slip ring 30 upon which bears a brush ill in electrical conununication through con doctor 32 with one terminal of the iron 27. At a diametrically opposed point the winding 28 permanent connection mad through conductor 33 with the slip ring 34 upon which bears the brush 35 which con- Ill) insulated from each other and rotate with the rotor 11. V v

The stetor 12 comprises the rin or yoke 38 of iron or other suitable iiig'i'ietic n12:- terial carrying the our poles 39; 4'0, 41, and 42 each provided with s magnetizing coil. 43. These coils 43 arc, here Show]; as connected in series with each other and all wound in the some direction with respect to the poles upon which they are From a point between one pair of coilsa conductor extends to a segment 45 0% the commutator or switching afipsrut-us 23. From a point between another pairof coils theconductor 46 extends to s segment 47;- frorn a point between another pair of coils extends the conducizor 48 to mother segment c9; and similerly from a point between the remaining pair of coils extends a con doctor-'50 lo the segmentkil.

fihe ink or lever 2o is secfir'ed to" the shaft 52- ceriried by and rotatshle' with re spect to the base carryi-rr l the segments 45, 47, llland 51. Insulated each ther and rotatable with the shaft 52 and lever 26 are the sli rings 53 and 54' upon which bear the brus cs 55 and 56 respectivel the brush 55 being' connected through c u'ctor 57 with one terminal of the source" 27 and the brush 56' connected through conductor 58'with switch contact 37.- Movable with the shaft 52 and handle 26 are the brushes 59 and 60, insulated fr'orneach other, and electrically connected respectively with the slip rings 53 and 54.

n closure of the switch 22 upoiioomtact 37 current will flow from the lower, for example, positive terminal of the source 27 through conductor 32, brush 31, slip ring 30, conductor 29, through both halves of the winding 28, returning through conductor 33, slip ring 3 l, brush 35, conductor 36, throng: switch 22 to the negative terminal of t source 27. The flow of the current through the winding 28 magnetizes the core 11 of the rotor to exhibit north and south poles on opposite ends of a diameter, which poles remain in substantially the same position with respect'to the core 11 during its to" tation.

Due to'the closure of the switch 22 current also flows from the lower terminal of the source 27 through conductor 57, brush 55, through slip riiig 53, brush 59, segme'iit l7, conductor 46, to the point a Where it divides flowing through the right hand find lower coils 43 in series to the p int b. andflowing also through the upper and loft hand coils 43 to the point 6 thence Eli rough co n' ductor 50 to segment 51, through 60, slip ring 54:, brl1sh 56', conductor 58; through the switch 22 to the rationin terminal of the so'flrce 27. In conso' lie'nce the? fides of the'poies and 41 will glib-loll sou-fh poles, for exanrole, while the fldes of the-{ 0112s 39 and 42 will exhibit north poles.

such case at with the horizontal from a.

point midway between the poles 39 and 42 through apoint midway between the poles and 41 as indicatedby the arrows 61.

The direction of the axis of the field of the rotor 11 extends in the direction of the arrows 62. There will then be n react-ion be tween rotor and stator producing motion of the rotor 11 in a clockwise direction as viewed in Fig. 2 tending to bring these msgnetic axes of the stator and rotor into coinciclenc'e. This reaction produces a torque on the shaft 9' rotating the same in clockwise direction when-viewed from the right hand end Fig. 1. The movement of the rotor 11- ho'we'xfer will not continue, as in an ordinary electric motor having its commutator and brushespdircctly attached to it and causing relative shifting of the field of th?! armature with respect to itself in opposite direction to jthc rotation of the arn'rature and to exactly the some extent of the rotation, whereby the armature continues to revolve. The rotor'll will come to rest unless the handle 26 is med to carry the brushes 59 and into cont-act with segments 49 and 45, and in doirig' so current will flow from the source 27 through conductor 57, brush55, slip ring 53, brusli 59, segment 49', conductor 48 to the point of where it divides, part goin in. series through coils 43 onpoles 39 an '40 itq the point 0 and part passing in series fthrough the coils 43 on poles 42 and 43 to Ethe point (1. Now the faces of poles 42 and while poles 39 and 40' 41 exhibit south poles exhibit north poles. in other words the axis of the magnetic ficldpf the stator h ts he axis of the magnetic field of the stator extends in shifted in a clockwise direction through 96".

But the axis of the magnetic field of the rotor has remained substantially constant with ties t to the rotor body and in conse queries t e rotor is rotated through a further And so on for the successivepositions of the handle 26fmoved in clockwise direc lion, Fig. 2, the rotor revolves 90 for each i the shaft 9 of the engine which Willsfurt; its opposing torque having been overcome by'the rotor 11,- it being assumed of course that the ignition \apparatus, not shown, has been set into operation and 't hethrott l'e', not shown, has been opened. After the engine is started the switch 22 maybe opened until 4 successive position of the handle 26, cumin-g torque is a maximum, and four alternate positions at which itis a minimum. The rotor is so placed as to its angular position upon a the shaft 9 with respect to the engine cranks that for every maximum occuring in the negative torque of the engine there will simultaneously occur a maximum in the torque of the rotor, the torque exerted by the rotor 11 upon the shaft 9 at such time beingin excess of the negative torque exert-ed upon the shaft 9 on the engine at the same time.

remain seated inthe machine and move the crank 26 in proper direction and the rotor 11 will execute movements following the movements of the crank 26, to crank the engine. And it is further'apparent that inthis arrangement my clcctro-dynamic starter does n t operate like the ordinary electric motor which continues to rotate so long as it remains in communication with a source of energy. Notwithstanding the closure of the switch 22 the rotor 11 will not continue to rotate, because the brushes 59 and 60 are mechanically independent ofthe rotor and are not shifted synchronously with it, as is the case of an ordinary electric motor where the brushes and commutator are mechanically shift-ed with respect to each other in syfichronism with the movement of the mm able motor element. 4

' In Fig. 3 I have-shown the stator ring 38 carrying cightpoles 63, 64, 65, 66, 67, 68.

'69, and 70 having thereon coils 63' to '70 respectively. The common terminals of coils (33 and 64' are connected by conductor 7 1 with the common terminals of the coils 67' l|l(l (38 and with segment 49 of the com:-

mutating apparatus. Similarly the common terminals of the coils 63' and 70' are connccted ,by conductor 7 2.with the common terminals of the coils 67 and 6G and with the segment 51. Similarly the common ter minals of the windings 70' and 69 are connected by conductor 73 with the common tramiuals of coils G6 and and with the segment. 47 .-\nd similarly the common terminals of the coils iti'hnd 69 are connected ihrough conductor 74 with the common ter miuals of coils fl t and 65 and the segment ii. The rotor ii in this case has in place of the two windings shown in Fig. 2, four windings 2 each extending through a quadrant only diametrically opposite points or the winding being connected to one slip ring 30 while diauu-trically opposite points,

at right angles to the first named points, are connected to the slip rings 34 and. through the respective brushes 3-5 and 31 with the source 27, when the switch is closed. In consequence the rotor exhibits -two north the axis of the other poles and two south poles, the axis of one pair of these poles being at right angles to alr.

lVhenfthe switch 22 is closed and the handle lever 26 rotated, the rotor will fol.- low in its movements the movements of the lever 26, its magnetic poles remaining substantiallyfixed with respect to the. rotor. The stator, however, due to the connections of the windings as described, exhibits two neighboring north poles, with two neighboring north poles diametrically opposite; also two neighboring south -poles with two neighboring south poles diametrically opposite. As the handle 26 is rotated through 90 the magnetic axes of the stator are rotated through only 45, with the result that the handle 26 must make two complete revolutions for one complete revolution of the rotor 11. Here again the arrangement is such that the torque of the rotor 11 has periodically recurring maxima and minima and, as previously stated, a maximum torque exerted by the rotor 11 shall occur substantially simultaneously with the maximum negative torque by the shaft 9 exerted thereon by the engine. And as in the previous case the rotation of the handle 26 causes a rotationof the shaft 9 for engine starting purposes.

In Fig. 4 the stator ring 38 carries six poles 75, 76, 77, 78, 79, and carrying respectively the magnetizing coils'75 to 80.

In this case the.s\vitching mechanism has six segments 81.. 82, 83,84, and 86. The segment 81 is connected through conductor 87 with the common terminal of the coils 75" and 80; segment 82 is connected through conductor 88 with the common terminals of coils 79 and 80'; segment- 83 is connected through conductor 89 with the common terminal of coils. 7S 'and 7?); segment- 84 is connected through conductor 90with the common terminal of coils 77 and 78; seg

'ment Siiis connected through conductor 91 with the common terminals of coils 7G and 77'; .and segment 86 is connected through conductor 92'with the common terminals of coils 75 and 76. The rotor is similar in its winding to that shown in Fig. 2. Here a sixth of a revolution of the handle 26 causes a shifting of the magnetic axis of the stator through a sixth of a revolution, that is, through 60 with respect to the stator. In the arrangement of Fig. 4 three neighboring poles simultaneously exhibit like polarity while the three opposing poles In Fig. 5 ordinates represent torque values and a-bscissse represent time or an-' gular positions of the engine crank shaft. The lower curve P represents, in general, the thrust against an engine crank, or-represents generally the torque of one cylinder of a four cylinder engine. The torque increases from the point It to a maximum at the point A: and diminishes again to the point Z. The upper curve Q represents the torque curve of a rotor of an electro-dynamic starter involving one form of my invention. Here it will be noted that a maximum occurs at the point m coinciding substantiallyv in time with the maximum is of the engine torque. And the points it of minimum torque represent torques substantially equal to or larger than the maximum torque is.

Th Fig. 0 the lower curve T represents the combined crank thrusts of two cylinders of a six cylinder engine during compression period and the upper curve Q is the torque curve of my electro-dynamic starter when having six poles, and commutator of six segments, and rotor, all as illustrated in the example of Fig. 4. Here again a maximum 122/ occurs substantially simultaneously with the maximum la. It is to be understood however that my invention is not limited to starters exhibiting with respect to the engine the relations exemplified in Figs. 5 and .6 for the relative values of the torques; and the two curves in each figure may be other than indicated. But as stated it is preferred that a maximum torque be exerted by the starter substantially simultaneously with the occurrence of the maximum opposing torque on the part. of the engine shaft.

In Fig. 7 is shown a form of starter whereby the operator need not turn the brush crank 26, of Fig. 2 for example, but in which one element of the commutator moves in synchronism or definite relation with the rotor,the other element of the commutator being stationary as regards rotation, and capable of connection and disconnection electrically and mechanically from the rotating element of the commutator at the will of the operator.

I11 Fi 7 the frame, rotor, stator, windings an connections are similar to those indicated in Fig. The shaft52 revolves in bearing 94 set in the dash board 7, or any other suitable location, and in bearing 99 in a suitable sup ort 100, said support 100 being bolted to 'ash board 7 b bolts 105. At one end of shaft 52 is a pulley 95 upon which travels a belt or chain 96 to pulley 97 secured upon shaft 9. Thus when shaft 9 revolves shaft 52 revolves in synchronism or in definite relation with it. Attached to the shaft 52 is arm 110 carrying brushes 55, 56,

5t) and 60; brushes 55 and 59 being connertetl together by conductor 102 and brushes 5t; and 60 being connected together by conductor 101. Base 25 is movable longitudinally of the shaft 52 but prevented from rotation by the bolts 105 and rods 106, the latter mechanically connected to the cross piece 108 carrying the handle 107. Segments 45, 47, 49 and 51 and slip rings 53 and 54 are secured to ,the insulating piece 25, and are held away from the brushes 55, 50, 59'and 60 by the springs 109. Slip ring 54 is connected to one terminal of the source 27 by conductor 57, and slip ring 53 is connected through conductor 58 to the contact 37 of switch 22. \Vhen the handle 107 is pushed inwardly in opposition to springs 109, brushes and 56 are engaged by slip rings 53 and 54 respectively. Brushes 59 and 60 are connected to the commutator segments 45, 47, 49 and 51 depending upon the position of the armature 110. As shown rush 59 is in electrical connection with segment 51 and brush 60 is in electrical connection with brush 47. Now if switch 22 is closed, the current will flow through the rotor as described in connection with Fig. 2. As to the stator windings, the current will flow from the source 27 through conductor 57 to slip ring 54, to brush 56, to brush 60, to segment 47, through conductor 46, to the point a and thence to the stator windings to the point I), as previously described in connection with Fig. 2, then by conductor 50 to segment 51, to brush 59, to brush 55, to slip ring 53, through conductor 58 to the other terminal of the source 27. The reactions between rotor and stator will cause the rotor to revolve-in clock-wise direction and so revolvingwill drive the shaft 9 which will revolve shaft 52 and the brush holder will shift so that the brush 60 will connect with the egment 49 and brush 59 will connect with segment 45. The field,

in the stator is correspondingly shifted and the reactions between rotor and stator will continue until the engine is started, when the handle 107 may be released and brushes and commutator segments mechanically and electrically disconnected by springs 109. As the engine continues to run the brushes may be rotated, but, being out of contact with the commutator segments, the Wear of brushes and commutator segments is avoided, as these are in mechanical and electrical connection only while the engine is being started.

The commutator of the rotating armature and the brushes of an ordinary motor for self starting are always in mechanical and electrical connection. The commutator brushes of the stator of my starter may -be put in mechanical and electrical connection and separated at will, thus saving wear when not in use. This principle applies Whether one of the elements of the commutator revolves synchronously with the shaft of the starter or not. If however both comniutator and brushes are stationary when not in use when starting there will be no wear, and it is not necessary to separate them mechanically and electrically.

It is to be understood that my invention is not limited to a stator which is provided with the concentrated poles or windings as shown, but thatv a stator having a great number of sections of windings may be em ployed, similar to a direct current armature winding, in which case. the number of seg ments in the switching apparatus or commutator apparatus will be correspondingly increased with the result that the maxima and minima of the resulting torque curves will not be so contrasted as in the case of the apparatus illustrated, but will have a characteristic torque curve which is more nearly a straight line, that is, indicating a more nearly uniform torque Nor do I wish to be limited to apparatus for starting an explosive engine of any particular type or number of cylinders, for my invention is broadly applicable to all types of explosive engines, and in fact to any other devices which, for starting, must be turned over or cranked.

I prefer that the windings upon the rotor of my starter shall be relatively coarse and be traversed by relatively heavy current,

hile the windings on the stator shall be aversed by relatively small current. In such case, since continuous slip rings continuously in connection, with brushes are employed, there will be no s arking at these members notwithstanding t e rotor is traversed by heavy current.

It is to be further understood that I may use separate sources of energy, one for enerizing the stator and another for energizmg the rotor. Or the stator may be subjected to either the entire or less than the entire electric pressure of the source and the stator may be subjected to either less than the entire or the entire pressure of the source.

\Vhile I have illustrated the rotor directly connected upon the engine shaft 9, it is to be understood that it may be connected to the engine shaft. through any suitable gearing, belting, or otherwise; and it is to be further understood there may intervene between the engine shaft and the rotor a clutch if desired. And it is to be further understood that the arrangements of Figs. 2, 3, 4, and 7 are not lmntive of my invention, for it is obvious, in view of the disclosure of these figures, combinations of rotor and stator windings of difierent num bers and modes of connection may be em ployed.

What I claim is:

-1. The combination with an explosive engine, of means for starting the same comprising a rotor and stator, a winding on the said rotor producing a magnetic field of substantially constant direction with respect to said rotor in all its positions, a stator winding, and switching mechanism remote from said stator controllin said stator winding, whereby the axis 0 the magnetic field produced by said stator winding is progressively shifted with respect to said stator, said rotor and stator fields producing non-uniform torque having a maximum substantially simultaneously with maximum opposing engine torque.

The combination with an explosive engine, of means for starting the same comprising a rotor and stator, a winding on said rotor producing a magnetic field of substantially constant direction with respect to said rotor in all its positions, a stator winding, and switching mechanism having a member movable independently of sai rotor controlling said stator windin whereby the axis of a magnetic field pr need by said stator winding is progressively shifted with respect to said stator, said rotor and stator reacting on each other to produce non-uniform torque having a maximum substantially simultaneously with maximum opposing engine torque.

The combination with an explosive engine, of means for starting the same comprising a rotor and stator, a winding on said rotor producing a magnetic field of sub: stantially constant direction with respect to said rotor in all its positions, a stator winding, said rotor and stator-reacting on each other to produce non-uniform torque having a maximum substantially simultaneously with maximum 0 posing engine torque, and switching mec anism having two movable members, one member movable independently of said rotor, and one member moving in synchronism with said rotor, whereb the axis of the magnetic field produced y said stator winding is progressively shifted with respect to said stator.

at. The combination with an explosive engine, of means for starting the same comprising a rotor and stator, a winding on said rotor producing a magnetic field of substantially constant direction with respect to said rotor in all its positions, a stator winding, switching mechanism having two movable members, one member movable independently of said rotor, and one member moving in synchromsm with said rotor, whereby the axis of the magnetic field produced by said stator; winding is rogressively shifted with respect to said stator, and means for disen aging said movable members from each 0t er.

5. The combination with an explosive engine, of means for starting the same comprising a rotor and stator, a winding on Said rotor producing a magnetic field of substantially constant direction with respect to said rotor in all its positions, a stator winding, switching mechanism having two movable members, one member movable independently of said rotor, and one member moving in synchronism with said rotor, whereby the axis of the magnetic field produced by said stator winding is progressively shifted with respect to said stator,

and means normally holding said movable dependently of said rotor, and one member moving in synchronism with said rotor, whereby the axis of the magnetic field produced by said stator winding is progressively shifted with respect to said stator, means normally holding said movable members disengaged from each other, and means for bringing said movable members into engagement' with each other.

7 The combination with an explosive en-' gine, of a starter therefor comprising electro-dynamically reacting rotor and stator exerting on said engine a torque fluctuating in magnitude and attaining a maximum substantially simultaneously with a maximum opposing torque of said engine, means for passing uncommutated current through said rotor, and means remote from said stator commutating the current in said stator.

8. The combination with an explosive engine, of a starter therefor comprising electro-dynamically reacting members exerting on said engine a torque fluctuating in magnitude and attaining a maximum substantially simultaneously with a, maximum op posing torque of said engine, and switching mechanism independent of said members controlling their relative movement.

9. The combination with an explosive engine, of a starter therefor comprising electro-dynamically reacting members exerting on said engine a torque fluctuating in magnitude and, attaining a maximum substantially simultaneously with a maximum opposing torque of said engine, and switching mechanism independent of said members controlling the direction and rate of fluctuation of their'torque.

10. The combination with an explosive engine, of starting means therefor compris ing a rotor and stator, rotor and stator windings, means for maintaining current flow through the rotor Winding in fixed relation thereto, and switching mechanism having a movable member independent of said rotor for progressively changing the relations of the stator windings, said rotor and stator reacting on each other to produce non-uniform torque having a maximum substantially simultaneously with maximum opposing engine torque.

11. The combination with an explosive en- 4 gine, of means for starting the same comprising a rotor and stator, rotor and stator windings, means for passing through the rotor winding a relativeiy large non-commu tated current, and i comm stat n controlling the stator winding comprising a fixed member and a movable member movable independcntl y of said rotor, said rotor and stator reacting on each other to produce non-unr form torque having a maximum substantially simultaneously with maximum oppos mg engine torque.

12. The combination with an explosive engine, of means for starting the same com-- prising a rotor and stator, a winding on said rotor producing a magnetic field of substantially constant direction with respect to said rotor in all its positions, a stator winding, switching mechanism having two incur bers movable into and out of engagement with each other, one member movable independently of said rotor, and one member moving in synchronism with said rotor, whereby the of the magnetic-field produced by said stator winding is pmgressivcly shifted with respect to said stator, said rotor winding carrying a relatively large noncommutated current and the current in said stator winding controlled by said switching mechanism being relatively small.

13. The combination with an xplosive engine, of means for starting thu same comprising a rotor and stator, a winding on said rotor, slip rings movabic with said rotor and connected to said winding, a stator winding, and switching mechanism therefor and remote therefrom comprising a plurality of non-rotating segments, ci'iopcrating rotating brushes, and slip rings in electrical communication with said brushes, said rotor and stator reacting on each other to produce nonuniform torque having a maximum substantially -llllllliilllttOUrillt' with maximum opposing engine torque.

14. The combination with an cxplr i gine, of means for sterling mic cone prising a rotor and s1 aior. a w in on said rotor, slip l'lli lllOYtilI'lr with id 1 L connected tosaid winding", 1: H3101 winding, switching mechanism tln-rcfor and remote therefrom comprising a plurality of statimr ary segments, coopcrininp it'izl illg in and slip rings in electrii mmml ilh with said brushes, and liii'zllh isur'nlfli ing said brushes and scfnnrm from each other.

i untherefrom comprising a plurality of stationary segments, cooperating rotating brushes,

slip rings in electrical communication with said brushes, means normally holding said brushes and segments separated from each other, and means for bringing said brushes and segments into engagement with each other.

16. The combination with an explosion engine exerting notruniform torque, of means for driving the same in starting comprising a rotor connected to the shaft of said engine and a stator, said rotor and stator producing magnetic fields re-acting on each other to produce a non-uniform torque attaining a maximum substantially simultaneously with a maximum opposing engine torque, sliprings and brushes for said rotor juxtaposed thereto, and switching mechanism remote from said stator for progressively shifting the magnetic field of said stator.

17. The combination with an explosion engine, of means for driving the same com prising a rotor and a stator, a stator Winding, and switching mechanism controlling said stator ing for progressively shifting the stat" @eld, said switching mecha nism comprising rotatable and non-rotatable members normally disengaged from each other, and means for engaging said members with each other.

18. The combination with an explosion engine, of means for starting the same comprising a rotor and'a stator, a stator Winding, switching mechanism remote from said stator controlling said winding for progressively shifting the stator field, said switching mechanism comprising rotatable brushes, and cooperating non-rotatable segments connected to said winding, and means for bringing said brushes into engagement with said segments and for disengaging said brushes from said segments.

in testimony whereof I have hereunto affixed my signature in the presence of the two subscribing Witnesses.

ROBERT C. HULL.

W itnes-ses:

MCKnn DUNCAN, EDWARD -LYNDON.

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