US1322471A - Dynamo-electric machinery. - Google Patents

Description

, L. L STEPHENSON. DYNAMO ELECTRIC MACHINERY. arvgxcmon ms mw l5. |919.

1,322,471 Patented Nov. 18, 1919.

5 SHEETS- SHEET l- L. 3. STEPHENSN. DYNAMG ELECTRIC MACHINERY. APPLxcMmN mm MAY 15. 1919.

Patented Nov. 18, 199.

5 SHEETS-SHEET 2.

MWF/95565:

L. J. STEPHENSON.

DYNAMO ELECTHICMACHINERY.

APPLICATION min www. |919.

1 ,32.2, 47 l Patented Nov. 18, 1919.

`ylg4 559.5

L. l1. STEPHENSON.

DYNAMO ELECTRIC MACHINERY.

APPLICATION msn 4m15.19l9.

1,322,471 13a-tema Nov. 1s, 1919.

5 SHEETS-SHEET 4.

` l..l l. SEPHENSON.

DYNAMD ELECTRIC MACHINERY.

APPuc/mon mm mums. m9.

1 ,322,47 1 Patented Nov. 18, 1919.

s sains-sagst 5.

5| 01g L* c E U0 aan' ma@ 22904 M00 76270 ,ewa 69005490 YZO-@P5066 -which are intended to be LE'IGH J'. STEPHENSON', 0F CHICAGO, ILLINOIS.

DYNAMO-ELECTRIC MACHINERY.

Specieation of Letters Patent.

Patented Nov. 18, 1919.

Application filed May 15, 1919. Serial No. 237,420.

TQ all whom it may concern.'

Be it known that I, Linen J. STEPHEN- soN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certainnew and useful Improveme-nt in Dynamo- Electric Machinery, of which the following is a full, clear concise, and exact description, reference being had to the accompanyng4 drawings, forming a part of this specication.

This invention`relatcs to improvements in dynamo electric machinery, and is especially concerned with improvements in dynamos used either .as generators or motors, my invention being particularly applicable to dynamos which are toI be used as motors for driving vehicles 'or mechanisms which are frequently started and stopped, or which are subject to variation in speed. *or economical reasons it is very desirable where the apparatus to be driven is of the type referred to above, andwhere the amount of power consumed is considerable, that the dynamo should operate as a generator when it is desired to stop the apparatus or to reduce the speed, thereby returning current to the line from which the dynamo, while functioning as a motor, receives its supply of current.

Various expediente have heretofore been suggested for controlling a dynamo to function as a motor, to drive certain apparatus, and to function as a generator when it is desired to stop or 'reduce the speed of the apparatus, the dynamo for this purpose acting as a dynamical braking means for effecting the desired reduction in speed. For various reasons these expedientel have proved undesirable in many instances', and especially so where it is desired that the d namo, when functioning as a motor, should have the characteristics of a series wound motor. This is due to the fact that theI apparatus heretofore required for producing an apparatus having the necessary or de` sired characteristics has been very complicated, of high initial cost, and the maintenance cost has been excessivev Furthermore, it has been found impossible with apparatus heretofore in'use, to provide for more than two or three braking rates without the use of complicated'andcostly auxiliary. controll ling apparatus.

Although it has long been recognized by railway engineers that the characteristics ot' a series wound motor are not the most desirable characteristics which a motor for this service could possess, up to the present tlme no means have been provided for producing a motor having characteristics that are more desirableY than those of a series inotor. y invention, more specilicall y speaking, relates to means for providing a motor having characteristics that are more universally desirable for electric railway opY eration and other similar service.

Iy invention also relates to improvef ments in dynamo electric machinery which it possible for a manufacturer of this kind of apparatus to manufacture a single line of dynamos and to provide con.-

trol apparatus therefor by means of which these dynamos can be controlled to give any desired characteristic, either of a series shunt or compound wound motor or generator, the control apparatus itself being comparatively small, economical to manufacture, and requiring very small upkeep.

Some of the objects of my invention are: First: To provide a dynamo and control apparatus the1efo1','wliich will function as a motor to `drive apparatus with which it is connected, and which will utilize the momentumbf the connected apparatus when functioning as a generator, to return power to the power circuit with which it is connected, and at the same time produce a dynamical braking effect upon the apparatus driven thereby;

,l Second: To provide an apparatus of the type described, by means of which the rate at which current is returned to the power' line and the braking effect produced can be regulated as desired;

Third To provide apparatus of the. character described, embodying means whereby the` rate of acceleration can be easily and economically controlled, as desired;

Fourth: To provide apparatus as set forth above, which is, comparatively speaking, of simple construction, economical to manufacture, easy to operate, and which has a low maintenance cost;

Fifth: To provide a dynamo whicli,when functioning as a motor, may be caused to have the operatin 'characteristics of either a shunt, series or 'compound wound motor,

as desired, 0r mayI be `ven operating characteristics different rom the operating characteristics of a shunt, series or compound wound motor;

Sixth: To provide a dynamo of the type referred to, which, when functioning as a motor, has operating chaacteristics similar to those of a series wound motor, and of such construction that when o-peratin as a generator its voltage may 'be control ed as desired, to effect any desired rate of dynamic braking;

Seventh: To lurovide a shunt wound dynemo with control apparatus whereb it may be caused to function as a motor aving the characteristics of a series wound motor;

Eighth: To provide a mbtor with means for regulating the speed thereof, so that't-he speed may be changed by imperceptible gradations; l

Ninth: To provide a motor havin an infinite number of speeds between its ow and hi h s eeds;

enti: To provide an adjustable speed motor having a large speed range;

Eleventh: To provide a dynamo which, when functioning as a motor, may be controlled to give various speeds fbetween its low and high speed, without the use of resistance or contacts carrying heavy cur rents;

Twelfth: To provide a dynamo of the character described, the speed of which can be easily controlled from a distance;

Thirteenth: To provide a dynamo wit-h control apparatus by means of which its operating characteristics may beeasily and quickly varied or modified; and

Fourteenth: To provide a dynamo, the operating characteristics of which can be varied or modified as desired, while operating. l

Other objects will appear as this description progresses, reference being had to the accompanyingdrawings, in 'which- Figure 1 discloses in a more or less conventional manner a dynamo designed to drive a street car or other vehicle, or apparatus, equipped with a regulating dynamo showing the driving connection between the motor and the regulating dynamo;

Fig. 2 is a diagram of the electrical connections between the various parts of my apparatus;

Fig. 3 is a set of curves illustrating eertain operating characteristics of the ap paratus disclosed in Figs. 1 and 2;A

Figs. 1, 5, 6, 7, and 8 are more or llessi schematic wiring diagrams illustrating certain modifications or variations of theelectrical connections illustrated in F ig. 2;

Fig. 9 is a side elevation of apparatus embodying a n-oditied formr of my invehtion;

Fig. 10 is a wiring diagram showing one 'present to Figs. 1 and 2, the reference character 15 indicates in a more or less conventional manner a dynamo, which is illustrated in the form of a motor designed to drive a street car or other similar vehicle. This dynamo is provided with an arn'iature shaft 16 to one end Vof which is secured a spur gear 17, designed to mesh with a suita le gear on the axle of the vehicle o-r apparatus to be driven. Mounted upon the end of the casing of the dynamo 15 adjacent the spur gear 17 is a small regulating dynamo 18. For the purpose of distinguishing between thew regulating dynamo and the larger dynamod, the latter will be termed a power dynamo. The dynamo 18 is driven at a speed bearing a constant proportionality to'the speed of the armature shaft', by means of a gear 19 secured to the shaft 16, which meshes with a gear 20 secured to the shaft 21 of the regulating dynamo. l

Referring' to F 2, the dynamo 15 is shown connected directly across the mains 22 and 23, by means of conductors 24 and 25, a suitable starting resistance S being connected in series with the dynamo 15. The conductor 24 includes a switch 24', for controlling the circuit of the dynamo 15. The reference character 26 indicates the shunt field of the dynamo 15, one end of which is connected with one terminal of the dynamo 15. The other end of the shunt field 26 is connected by means of the conductor 27 with one terminal of the regulat ing dynamo 18. The other termina-l of the dynamo 18 is connected by means of the conductor 28 with the conductor 25. By means of the connections just described, the field 26 and the armature of the regulating dynamo are connected in series with each other, and in shunt about the armature of the power dynamo 15. The reference character 28 indicates the field of the regulating dynamo 18. The field 28 is connected arbund or in parallel with the shunt field 26 of the power dynamo by means of the conductors 29 and 30. An adjustable rheostat 31 is included in the circuit of the field 28 of the regulating dynamo 18. The regulating dynamo 18 is connected with the shunt field 26 of the power dynamo in such a manner `that its voltage, that is, the voltage of the switcht is then closed,

'used for driving apparatus shunt field of regulating dynamo, opposes the voltage impressed upon the shunt field of the power dynamo by the mains 22 and 23.

For the purpose of explaining the operation of my apparatus it will be assumed that thel dynamo 15 is to be used for dr1ving a motor vehicle such as a street car or automobile. It is very desirable that the motor ot' this kind should be a series motor or at least should -have characteristics similar to a series motor on account of the exceedingly high starting torque developed by a motor of this kind and on account of its rapid acceleration.

AThe dynamo 18 is so connected with the the dynamo 15 and the line wires that its voltage opposes the voltage imposed on the line wires. In starting a vehicle equipped with my improved apparatus the ustable member 32 of the rheostat 31 is manipulated toward the 'left in Fig. 2 to open the circuit of the field 28 pt the dynamo 1S, thereby reducing the (incitation of this dynamo to substantially nothing, and

Aconsequently reducing the voltage ot' the d name 18 to its he starting, resistance rlowest possible voltage. S is eut in and the whereupon the full line voltage reduced by the starting resist! ance S is imposed upon the tern'iinals of the dynamo 15 and full line voltage imposed upon the shunt field of this dynamo. Since the armature 15. is at rest a very heavy current Hows therethrouglnaml since the armature 18 is at rest it does not produce any lelectromotive force to oppose the passage of current through the shunt'teld 2o of the dynamo 15, and consequently the maximum ciirrent flows through the field 26. By reason of the heavy currents in the armature and field of the dynamo a large starting torque is developed. The armature of the dynamo 15 will speed up under this large torque and in the absence of the dynamo 18, would accelerate in substantially the same manner as the shunt dynamo. llowever, as the dynamo 1S is in geared connection with the dynamo 26 its armature -will speed up at tho same rat/e as that of the dynamo 15. It,

` after closing the switch 24 and thus starting the dynamo 15 asa motor, the operator immediately moves the contact 32 of' the rheostat toward the right, the resistance ol' the rheostat 31 isv gradually cut out, thereby gradually increasing the field strength ot' the dynamo 18. At the same time thc speed of the armature ot the dynamo 18 is gradually increased and as a result of these increases in the excitation of the field of the dynamo 18 and the speed of its armature, the voltage of the dynamo picks up at a rapid rate. As thi.` voltage opposes the voltage imposed upon the field Z6 ol' the dynamo 15` the field .trength of the dynamo 15 is devoltage generated by the dynamo 18. 'l`he creased at a rapidly accelerated`rate. The result of this is that the speed of the armature 15 is accelerated at a much greater rate than it would be in the absence of the dynamo 18. As a matter of fact, the acceleration curve ot' my dynamo functioning as a motor and regulated as described resembles that of a series motor. It will, of course, be obvious that the rate ot' acceleration depends upon the rate at which the movable contact 32 of the rheostat 31 is moved toward the right.

The voltage or counter-electromotive force of the dynamo 1H and the line voltage should bear such a relation to cach other that when all of the resistance of the rheostat 31 is cut out the difference between these two voltages will cause the proper amount of current to flow through the shunt field 2u to cause the armature of the dynamo l5 to rotate at the desired highest speed.

When it is desired to decrease the speed of, or stop a vehicle, equipped with my apparatus, the movable contact 32 of the rheostat 31 is moved to the left-hand side of the rheostat 251 so as to cut in somc or all of the 'resistance ofthis rheostat, depending upon the `braking rate desire'l. This causes a decrease in the current llowing through the field 2B and correspondingly decreases the current flowing through the field 2t', immediatcly increases, thereby causing an increase in the saturation of the field dynamo l5. This dynamo thereupon ceases to function as a im tor and starts to function as a generator, the momentum of the vehicle supplying powerfor driving the dynamo as a generator. As

the power delivered to the liuc by the generator must he furnished b v the momentum of the vehicle the speed of the armature of the dynamo l5 and consequently of the vchicle decreases until the voltage of thc d vnamo 15 becomes equal to or slightly less than that of the line, whereupon the dynamo 15 again functions as a motor and continues 110 to 4drive the vehicle at a' reduced speed. lVhen the vehicle is running, hy completely opening the circuit of the field 2H the voltage ol' the generator 18 is reduced to practically nothing and the full voltage of the line is imposed upon the shunt.ficld 26, and the speed of the dynamo 1.7, and consequently of the vehicle, is reduced to that speed at which the dynamo with its field fully excited, gcncrates a voltage slightly less than that of the liuc. To bring the vehicle to a complete stop brake mechanism ol some sort may he employed. i

The speed of the armature of the dynamo 15 can he changed from its lowest speed` t0 125 its highest speed by simply moving the con tact 3Q from the lefthand end of 'therheostat 3l to the righthand end thereof, and to decrease the speed of the dynamo this operation is merely reversed. The resistance ele- 4130 characteristics and the advantages ot' my` ments of the rheostat 31 can he so proportioned that the changes in the speed ot' the dynamo 15 due to the shifting of the movable contact 32 may be made by impr-reep tible. gradations.

In vorder further to explain the operating improved apparatus, I have illustrated herewith a set of curves which 1 shall now cxplain. These curves illustrate the performance of the power dynamo functioning as a motor. y

In this figure (Fig. 3) the curves A. B land C show the change in speed of the motor with change in voltage applied to the terminal of the motor field Winding. Curve B shows the changes in speed with zero arma ture current. driving the motor at such a speed as to reduce the armature current to zero. Curve A represents the speed of the motor while carrying full load current with different potentials applied to its field terminals. and curve C indicates` the speed of the motor at full load brakingr current. Lines I to l.' inclusive correspond to different settings of the rheostat 3l, and serve to indicate two things, namely, the voltages Igenerated b v the regulating dynamo 18 and the voltages applied to the eld terminals ot' the motor. The distance between the line Y- and the line A-n.' is a measure ot' the voltage across the motor ield terminals when the field cir cuit of the. dynamo field 28 is opened. Under this condition the voltage applied to the motor field is practically equal to full line voltage. The distances between the intersections of the curves A, B and and the line Y-e and the axis 0- r are measures of the voltages a )plied to the motor teld terminals, and the distances between the. same intel'- sections and the line Y-J are measures of the voltages generated by the regulating dynamo for the same setting of' the rheostat 31. In a similar manner the distances between the intersections of the remaining lines e to 1 inclusive and the lilies A, il and C and the lines O-.r and Y-fl are measures of the voltages applied to the motor field terminals and the voltages generated hy the regulating dynamo. The lines rf to l' inclusive correspond to settings of thc rheostat 31, which give equal increments of ampere turns in the regulating dynamo field winding. Y

With a setting of the rheostat corresponding to theJ line Y-c. at no load, or rather with zero armature current the speed ot' the motor is approximately 560 R. l. M. As the load on the motor is increased, the speed will gradually decrease, until when the niotor is carrying full load current, its speed will have dropped back along the line Y--c to the intersection of this line with the full load curve A, which is approximately 45() This curve was obtained by.

R. P. M. If the motor should be considered as driving,r a vehicle, and it should en* counter a down grade, the speed would .increase along the line Y-w, until at the intersection of this line with the line C, it. would be generating full load braking current. In the same manner the s eed of the motor for any given setting of t ie rheostat or its braking* current can be determined by reference to the points of intersection of the lilies representing the different rheesht settings with the curves A, B and C. By shiftingr the rheostat from the point correspending to the line Y-j toward the point corresponding to the line Y-d, any desired rate of braking can be produced. If the. rheostat is shifted from the first mentioned position to the last mentioned posi tion, more quickly than the speed of the motor can decrease to the value indicated by the intersection of the line Y--al and C, the braking current will exceed the full load braking current of the main dynamo. Un the other hand, if the rheostat is shifted toward the position indicated by the line YMJ at the proper rate, the motor can be made to return current to the line at its full load rate while the speed of the vehieie1 is decreasing from its highest speed to its lov/ estspeed, indicated by the intersection or the line Y-d and the curve C.

It will be noted from an inspection of these curves that the lines representing the various rheostat settings intersect the curves A, B and C but once. This is a most important feature of my invention, for the reason that if any one of the lines representing the rheostat settings should inter-` sect the same curve, either A, B or C, twice,

become unstable. and it would rapidly in-'f` crease, taking more and more current, until the motor would either burn out, or Wreck itself, due to high speed.

Another important feature of my apparatus resides in the fact that the strength ot' the motor iield increases as the load upon the motor increases. This is clearly illustrated by the curves shown .in Fig. 3. Take, for instance, the line Yw-Ji, the maximum speed of the motor correspondingr to this rheostat settingat no load, which is ap proximately indicated by the intersection of this line with the line B, is approximately 12T!) It. I. M., and at this speed the voltage over the motor field is approximately (iti volts. As the load increases the speed drops back along* the line Y-fi until the load has heen increased to full load, when its speed will have decreased to approxilos mately 600 R. P. M. At this speed the voltage across the motor field terminals is approximately 11S volts. In other Words, in decreasing from a no load speed of 1:27() to a full load speed of 600, the voltage over the motor eld terminals bled.

Referring again to the curves shown in Fig. 3, it will be noted that the voltage which the dynamo murt generate in order to cause the motor to speed up under any load condition must initially increase at a very much faster rate than the speed of the motor. This will be made clear by reference to curve A. It will he noted that under full load, while the speed ot the motor is increasing from, say 500 R. I. M. to 80() R. P. M., the voltage of the regulating dynamo increases from approximately 50 volts to 122 volts. The increase in speed is 6U` per cent., whereas the increase in voltage of the dynamo is 14a per cent.

It will readily be seen that if the voltage of the dynamo should continue to increase at a greater rate than the speed of the motor increases, the field of the motor would decrease at a rate greater than the speed of the motor increases, and the motor would take av continuously increasing amount of current at an increasing speed. The speed of the regulating dynamo would increase with the speed of the motor, until a point would he reached where it would generate a counter-electroinotive force equal to line voltage, and since this counter-electromotive force opposes the line voltage impressed A upon the motor field Winding, the motor field would be reduced to zero. ln order, therefore, to prevent the motor from running away and burning out, it is necessary to provide some means which will, after the motor has reached a certain speed, cause the speed of the motor to increase at a faster rate than the voltage ofthe dynamo increases.

That l have provided such a means will he apparent from a further study of these` curves. and to illustrate this l will refer to the. portion of' the curves extending beyond 1000 lt. P. M. Referring again to the full. load curve. as the motor speeds up from 1000 Il. I. M. to 1G00 R. P. M.. which is an increase of GU per cent. in speed, the voltage ol' the dynamo increases from 112 to 17() per cent., or an increase in voltage of 19.7 per cent.

From these figures it will be seen that while the speed of the motor is increasing V per cent., the voltage of the regulating dynamo is increasing but 19.7 per cent.

From the above it will be seen that the dynamo voltage necessary to raise the motor speed through successive values must in- ?rease faster than its speed increases, until the knee of the curve-is reached, which is at has almost dou` Athe motor about 900 R. P. M. At this speed for an infinitesimal space, the dynamo field need not be changed, as the dynamo voltage is increasing at the Same rate its speed. Beyond this point the dynamo voltage must increase at a lesser rate than its speed increases. Siuce the dynamo voltage is proportional to the product of its speed and field strength, this means that the dynamo field must from this point be gradually decreased.

In order, therefore, to get the full speed range ofthe motor, the dynamo field must be increased up to a certain point, and then decreased for any further increase in speed. To accomplish this result I provide a field Winding for the regulating dynamo, which includes a rheostat, and which is connected in parallel with the motor shunt field. Tith this arrangement the gradual decrease in the strength of the'dynamo field is automatically accomplished, for at the higher speeds the voltage of the dynamo field circuit is dropping, due tothe fact that the current through the motor field is decreasing, and consequently the voltage over the dynamo field is actually decreasing, in spite of further decrease of the rheostat resistance. This makes the action continuous and inherent, and the higher speed settings are readily obtained regardless of load conditions.

As stated above, there is a point at which there is no change in the strength of the dynamo field. In other words, this is the point at which the field of the dynamo ceases to increase. I shall now determine this speed by reference to curve B of Fig. 3, this curve being used for the reason that it is the no current curve of the motor, and simplifies the calculations required to dtermine this point. i

If flux values in the magnetic field circuit of a direct current motor are plotted against speeds corresponding to each of these flux values, the resulting curve is an equilateral hyperbole. If in place of flux values, the voltage impressed upon the terminals of the motor field winding are plotted. the resultingr curve is almost -identical with the curve obtained b v plotting flux values against speed values, the only diierence being that by reason of the eli'ect of the magnetization curve of the iron forming the maguet field ofthe motor, one end of the curve is slighly distorted. The curves A, B and C of Fig. 3 show the relation between the motor speed values and the voltage impressed upon the mot/or field Winding to 0b tain these various speeds. The upper ends of these curves are, due to the above mentioned 'effect of the magnetization curve of the iron and field circuit, bent slightly away from the axis of zero speed. There are certain other things which slightly distort the curves A and C, such, for instance, as armature reaction and armature I R drop, which do not affect curve B, and since, therefore, curve B more nearly approximates a true, equilateral hyperbole, I shall use it for the present demonstration.

Now let o equal the field flux of the regulating dynamo, S equal the speed in R. P. M. of both the dynamo and motor, L equal line voltage, C equal the Windin Vconstant of the dynamo in the equation. 72 equals 09S where V2 equals the volts generated by the dynamo; that is, its connter-electr-emotive force. And let V1 equal the volts required at the motor shunt field terminals. The equation of an equilateral hyperbole is V 1SzK'z (l) This is the equation of the curve B referred to the axes 0-3/ and Own?. This is the equation of the curve which is the locus of the' values of the voltages applied to the motor field terminals for different speeds.

The voltages generated `by the dynamo equal the differences between line voltage and the various voltages applied to the motor field terminals, or

VlzLT-V2 (2) Substituting this value of V1 in (l),

SLSV2=K2 maximum value of 4 that is, w ere it starts to decrease,

but

zn=croa U) Placingqthis derivative equal to zero,

Therefore, the speed at which the field of the dynamo is at its maximum value is equal to K The ratio Substitutinglthis value of S in the equation,

VIS K2 In other words, the dynamo field reaches its maximum value when the voltage over the motor field terminals equals one-half the line' voltage. It will be noted by reference to the equation (8) that the critical speed is independent of the dynamo design, and also independent of the relative speed of the motor and dynamo,

By providing means for decreasing the dynamo field after; the motor has reached the critical speed above determined, I am enabled very considerably to extend the working speed range ,of the motor. With out this means the maximum speed will be reached when the dynamo field is at its maximum value. The speed at this point is as shown above;

The minimum speed is at the point Where max. speed 2K2 K2 In other Words, if no meansy are provided for decreasing the dynamo field after this critical speed has been reached, the maximum increase in speed which it is ossible to obtain `for any design of motor or ynamo and any speed relation between them is one hundred per cent. Practically this increase cannot he obtained. The saturation vot the magnetic. circuit, armature reaction, and ohmic drop all reduce this amount materially.

Reference to curves A, B and C of Fig. 3 discloses the` fact that any change in load from the no load curve, either toward the curve A or toward the Vcurve C is accompanied by a change in speed. @hat is, if the mechanical load upon the motor insfo ing dynamo field circuit is due to the resultant magneto-motive force of the two Windings Q8 and 50 and can therefore be varied by adjustment of the rheostat 31.

In Fig. 7 I have illustrated different connections hy means of which the current in the main field winding 28 of the regulating dynamo can 4be caused to vary proportionately to the flow of current in the field winding 26 of the power dynamo, and can also be regulated as desired. In this figure the main field winding 28 of the regulating,r dynamo is shown connected in. series with the armature of the regulating dynamo, and the shunt field winding 26 of the power dynamo. This arrangement produces exactly the same result as the shunt connection illustrated' in Figs. 2. 4 and (i. The current in the field winding 28 may he regulad by the rheostat 31, which, as shown, is connected in arallel with the field winding groin the above description it Will be clear tha-t when the dynamo 15 is functioning as a motor, it could be caused to have a lower stable running speed if some, means could be provided for causing the regulating dynamo 18 to reverse. its polarity and generate an eleetrolnotive force in a direction to assist the line voltage to give the dynamo l5 a very strong field. ln Fig. 8 l have illustrated means for accomplishing this result. 1n this figure the reference character 8O illustrates a lever pivotally mounted at 81 and carrying a pair of contacts 82 and 83, upon opposite sides of the pivot point 81, these contacts being insulated i n any desirable-manner from each other. The reference character 28 indicates the field windinij of the regulating dynamo 18, the termina s of which may he coilnected by flexible conductors 84 with the movable contacts 82 and C? Stationary contacts 85, 85. 86. and 8G form part of the reversing switch mechanism lit-.ing described. The lower end of the lever is provided with two laterally cxtending cams 87 and 87. which are adapted to he actuated by the roller 88 ou the rheostat arm 89. The reference characters (l to o inclusive represent contacts of a rheostat. The contacts y to o inclusive are connected by means of resistance elements y to n inclusive. Conductors c1. to e inclusive connect the con'tacts f1, to e inclusive with thr;

contacts g to inclusive, respectively.

'hen the rheostat 89 is in the position indicated in Fig. 8, the field of the regulating dynamo 18 is opened, and the power dynamo is operating at substantially its lowest speed. By moving the rheostat arm 89 to the right, the roller 88, by (zo-acting with the cam 87', first causes the lever 80 to tilt in a direction to cause the movable Contact 82 to make connection with tact and movable contact 83, to make connection with the stationary contact 86 the 'stationary con- Further movement of the rheostat arm 89 cuts resistance out of the circuit of the field 28, thereby increasing the voltage of theregulating dynamo 18 and thus increasing the speed of the motor 15. If the rhcostat arm 89 is moved from the position indicated toward the left, it first co-acts with the cam 87 to tilt the lever 80 in such a manner as to bring the movable contact S2 info elec` trical connection with the stationary contact 85 and the movable Contact 83 into electrical connection with the stationary contact 86, and upon further movement of the rheostat arm 89 toward the left, current will fiow through the field winding 28 in a direction opposite to that in which it flows when the rheostat arm 89 is in contact with the right hand contacts of the rhcostat. When' the rheost-:t arm is in contact With the contact r, all of' the resistance elements g to n. inclusive are in series with the field winding 2H, hut as the arm 8S) is moved toward the left, these resistance elements are progressively eut out and the current flowing thro-ugh the field winding 28 is thus progressively increased. Upon the reversal of the field 28 the dynamo 18 is caused to generate a potential, which assists the line voltage to pass current through the field winding 26 and continued movement of the rheostat arm toward the left causes this current to increase and the speed of the motor 15 correspondingly to decrease.

It will, of course, be understood that the means which I have illustrated for accomplishing the results just discussed are merely illustrative, and any other suitable means may he used for producingthe same result.

.The result produced by this means is substantially the same as that produced by the field winding 50 off l `ig. 5.

1n Figs. 9 and 10` l have illustrated a shunt wound dynamo and means for controlling said dynamo to function either as a, motor or a generator, the operating characteristics of' said dynamo, when functioning as a motor, being similar to the characteristics of' a series motor, this apparatus being tree from any of the objections to the means heretofore employed for causing a series motor to operate as a` generator for either dynamic or regenerative braking. This ap- Euns is the same as that illustrated in my copi-:mung application Serial No. 240,937, filed June 20, 1918, of which my present application constitutes av continuation in part.

Referring to these figures the reference character 15 indicates as a whole a dynamo which is.n1ore orlessconventionally illustrated, said dynamo comprising an armature shaft 16, to one end of which is secured a driving pinion 17 and to the other end of which is secured a friction disk-93. Mounted upon a support 94 secured to the dynamo frame cu' to any other suitable support is a smalll shunt wound regulating dynamo 18 havingl an armature shaft 96. A fri'ction wheel 97 is splined to the shaft 96 and positioned so that its periphery contacts with the face of the friction disk 93. The

friction disk 93 and the movable friction.

Wheel 97 form a well known type of variable speed gear by means of which the speed of the shaft 96 is increased as the friction Wheel 97 is moved outwardly from the center of thedisk 93 and decreased when the friction Wheel 97 is moved in the opposite direction. As means for moving the friction Wheel relative to the friction disk I h ave illustrated a rod 98 slidably mounted in suitable bearings 99 and 99', one end of said rod being provided. with a yoke 100 received in an annular groove 101 in the hub of the wheel 97. A link 102 has its lower end secured to the upper end of the rod 98 and the'upper end of the rod 102 is pivotally connected with one end of a lever 103. The lever 103 is pivoted to any suitable support at the point 101 and may be provided with a suitable handle 105.

From the above description it will be aparent that the speed of the dynamo 15 may Ee varied by imperceptible grada-tions from zero to its highest speed, and vice versa by merely moving the handle 105 up and down.

By thus' changing the speed of the dynamo 15 its counterelectromotive force will be correspondingly increased and decreased y very small increments.

Referring now to Fig. 10, in which l have illustrated the electrical Vconnections of mv apparatus, the reference character 15 indicates the dynamo which, shown, is connected directly across the mains 22 and 23, a switch 24 being interposed in the circuit of the dynamo7 whereby it may be connected and disconnected from the line. The reference character 2G indicates the shunt field of the dynamo 15. which is connected in series With the armature of the dynamo 18, the shunt field 26 and thel armature of the dynamo 15 being connected directly across the line. The reference character 28 indicates the shunt field of the dynamo 18.

For the purpose of explainingr the opera tion of my apparatus it will be assumed that the dynamo 15 is to be used for driving a motor vehicle such as an automobile, a street car, or an elevator. It is very desirable that the motor used for driving apparatus of this kind should have characteristics similar to those of a series motor on account of the exceedingly high starting torque developed by a motor of this kind, and on account of its rapid acceleration. The dynamo 18 is so connected with the shunt field of the dynamo `15 and the line Wires that its voltage opposes the voltage imposed on the line wires. In starting a vehicle equipped with my improved apparatus the lever 103 is operated to bring the friction disk 97' to the position adjacent the periphery of the friction disk 93, at which it will be driven at its highest speed.. When the switch 24 is then closed-current will pass through the armature of the dynamo 15 and also through the shunt eld 26 thereof. Since the armature of the dynamo 15 is stationary the flow .of current therethrough will be at a maximum and, since the speed of the dynamo 18 at the moment of starting is zero, itwill offer no opposition to the passage of current through the shunt winding 26, and conse` quently the fields of the dynamo `15 now i functioning as a mote` will be saturated. The result is that the dynamo 15 functioning as a motor will starting torque which will be comparable to that of a series motor of the same power. As the speed of the armature' of the dynamo 15 increases the speed of the armature of the dynamo 18`will likewise increase, and the increasing counter-electromotive force of this dynamo will oppose the voltage impressed upon the, shunt field 26, and thereby cause the shunt field to be gradually weakened. rIlhe weakening of the shunt field results in the acceleration of the armaproducea very large i ture of the dynamo 15 just as in a series y motor. The counter-electromotive force ofthe dynamo 15 and the line voltage must bear such a rela-tion to each other that atthe desired highest speed of the dynamo l5 the differences between these two voltages will cause the proper amount of current to flow through the shunt field to cause the armature of the dynamo 15 to rotate at the desired speed.

Then it is desired to stop or decrease the speed of a vehicle equipped with my apparatus the handle is operated to move the Wheel 97 toward the center of the disk 93.

This will cause a. reduction in the speed of the armature of the dynamo 18 and a correspondin reduction in the counter-electromotive orce of this dynamo. The current through the field 26 will be correspondingly increased, thereby strengthening the field of the dynamo 15 to such an extent that it will cease functioning as a motor and start t0 function as a generator, the momentum` of the vehicle supplying the power for driving the dynamo as a generator. As the power delivered to the line by the generator must be furnished by the momentum of the vehicle, the speedl of the vehicle and consequently of the armature of -the dynamo 15 decreases until the voltage of the dynamo 15 becomes equal to or slightly less than that of the line, whereupon the dynamo 15 a ain functions as a motor and continues to rive the. vehicle at a reduced speed. When the vehicle is ruiming, by moving the wheel 97 los inwardly to the center of the disk 93, at which point the spe ld of' the armature of the regulating dynamo 18 becomes zero, and the full voltage of' the line is im osed upon the shunt field 26, the speed of t e dynamo 15 and consequently of the vehicle, can be reduced to that speed at which the dynamo, with its field fully excited, generates a voltage equal to that of the line. To bring the vehicle to a complete stop brake mechanism of some sort must be employed.

The speed of the armature of the dynamo 18 may be gradually changed from zero to its highest speed or vice versa, whereby a corresponding change inY the counter-electro- Vmotive force of the dynamo 18 will be produced. This change in the counter-electromotive force of the dynamo 18 will produce a corresponding gradual change in the current fiowing through the shunt field 26 of the dynamo 15 and thereby gradually change the speed of the dynamo. The dynamo when functioning as a motor w1ll therefore have an infinite number of speeds and a change in speed may be accomplished without causing the vehicle to be driven in a jerking manner, as where the speed of the motor is controlled by the use of resistances or by connecting the motors, if there are a plurality of motorsconnected in different relations, such as in a series parallel control of street car motors.

Due to the fact that the entire speed control is obtained by regulating the strength of the dynamo field, in services where a wide speed range is desired, it will be advantageous to provide the dynamo with interpoles excited by coils in series with the armature 1n the usual manner. Thls W1ll prevent sparking at the eommutator, due to armature distortion of a weak field.

In Fig. 11 I have illustrated apparatus which is substantially a combination of the apparatus illustrated in Fig. 5, with that illustrated in Figs. 9 and 10. The power dynamo 15 is provided with a series field winding 40, a eommutating field windin r 41, and a shunt field winding 26. The s unt field winding 2G is connected in series with the regulating dynamo 18 and the -ield winding circuit thus formed is connected across the line wires 22 and 23. The regulatin dynamo 18 is provided with a field win ing 28, shunted about the field winding 26 ofthe power d ynamo, and with a second reversing field winding, likewise slfanted around the power dynamo field winding 26. A rheostat 120 may be connected in series with the reversin winding 50 to regulate the efiect of this winding if so desired. The powerdynamo and the regulating d name are shown equipped with a friction disk 93 and a friction wheel 97, respectively', by means of which the speed ratio between the two dvnamos can be-yai'ied, the apparatus .means are,

by means of which the friction wheel 97 is shifted along theshaft 96 of the regulating dynamo being omitted for the sake of' clearness.

The apparatus just described provides two posslble means by which the operating characteristics of the power dynamo 15 can be materially affected or varied. These first, the variable speed connection between the power dynamo and the reg uiating dynamo, and second, the adjustable rheostat 31 in the main field winding of the regulating dynamo. By varying either one of these instrumentahties separatel the power dynamo can be given certain c aracteristics, and by varying both of these instrumentalities the power dynamo can be given still other characteristics.

In Fig. 12 l have shown curves illustrating characteristic performances of the apparatus illustrated in Fig. 11. The curves A', B', and C shofwn in this figure correspond to the curves A, B, C of Fig. 3, except that the spacing of these curves, due to inherent drop in speed with increase in load, is effected by the series field 4.0, which contains a comparatively few turns. It will, of course, be understood that the number of turns in the series field 4() can be varied to give any desired inherent drop in speed with increased load.

lt will, of course. be understood that the maximum rate of regeneration may be controlled by varying the number of turns in the series field 40, and that the speed range of the, motor is reduced by increasing the number of turns in this field. 1t is therefore desirable that the number of turns in the series field 40 be restricted as much as possible in order to give the motor a Wide speed range.

The power dynamo and the regulating dynamo, of which the curves shown in Fig. 12 are characteristic curves, have substantially the same maximum speed, namely 1800 R. I. M. The curves Il', e' show the voltages generated by the regulating dynamo at various speeds, the curve Il corresponding t0 one setting of the rheostat, and the curve e corresponding to.anothcr setting of the rheostat, which gives top speed at one-third of the rated load of the motor. The curves d' and c are obtained with a one tof'one speed ratio between the power dynamo and the regulating dynamo. rThe curve f shows the generated yolts of the regulating` dynamo with a rheostat setting corresponding to the setting required to give curve d', but with a speed ratio of two to one between the regulating dynamo and the power dynamo; that is, when the regulatin r dynamo is operating at twice the speed of t e power dynamo.

W ith a speed ratio between the dynamo and motor of one to one, and the rheostat set for line d', the speed at noload is 880 R. P. M. and at full load 560 R. P. M., or the regulation is 57 perl cent.

By .changing the setting of the rheostat to that shown by line e', the speed at no load is 2200, and at full load 620, and the regulation is 255 percent. This showsthat the motor slows down due to load relatively more at high speed than at low speed, pist the saine as a series motor. If now, with [a rheostat setting corresponding to line d',

instead of changing the rheostat setting, the gear ratio between the power dynamo, and the regulating dynamo is changed to two to one, the speed of the motor will follow along the line f' with changes in load. The line is derived from the line d by plotting for each motor speed the dynamo voltage generated at twice that speed. With this setting of the rheostat,'the speed at no load is 2000 R. P. M., and at full load is 1200 R. P. M., and the regulation is 66 per cent. It will be noted that the curves e and f' intersect at approximately 1800 R. P. M. This means that in actual operation either setting e or f will drivejthis particular ower dynamo at full speed, namely 1800 i. P. M.. and '33 per cent. of rated load.

Ir. 'going from thisload .to full load with settin-iy the change in speed is 600 R. P. M. or 5619er cent. of its speed at full load. iVith lm .2- e change inspeed is 1180 R. P. M. or 1,9 per cent. of its speed at full load.

From the above it willf be seen that the setting f" gives a motor f haracteristic similar to that of a compound motor.V Setting e gives a characteristieimilar to that of a series motor.

With the setting e when the load is increased from one-third to full load, the speed drops to one-third its value at onethird of full load. At the same time the voltage over the shunt field increases from approximately 38 volts to approximately 124 volts, or 3:1, times its value at load. the armature resistance is comparatively low, the ohmic dro due to armature resistance may be neg ected, and especially if the motor is an interpole motor, for the reasonthat the interpoles will more than compensate for the armature drop. The dro in speed to one-third its -maximdlm full oad speed ini-igt necessarily mean that the flux in the field "is three times its value at onei-third full load. The increase in voltage oi'Lr the shunt field alone would not produce this increase in fluit dile to magnetic saturation. The additional ampere turns required to produce this increase in flux are supplied by the series field 40. With the setting e' thc torque increases with the Square of thel current thloughout the speed range of the motor. This is considerably more than can be accomplished with a series motor. I n order to give the power dynamo 15 the char- ,ing 40, and for this acteristic of a shunt motor, it is necessary to overcome the effect of the Series field windmeans lI provide a switch 10', whi h can be used for short circuiting the series field winding 40, and thus neutralizing its e'ect. The only drop in speed with increase in load which can then occur must be due to the armature drop, and since the armature resistance is very low, the effect of the armature drop upon the speed of the motor will be practically m'l.

The use of the regulating dynamo to give the power dynamo, when functioning a motor, the characteristics of a shunt motor, presents certain advantages over the use of an ordinary shunt motor in combination with a rheostat by means of which its speed can be varied. 'With the ordinary shunt motor and a rheostat, there is a constant loss in the rheostat, this loss being' comparatively small at higlrspeed but quite considerable at low speeds, depending upon the size of the shunt field current. lith my apparatus the regulating dynamo really functions as a motor to help carry the load of the power dynamo when functioning as a motor, and the only losses occasioned by its use being due to the usual internal losses in a motor. While I have illustrated and described certain embodiments of my invention, I aml aware that there are many other modifications of my invention which I have neither illustrated nor described. but all of which embody the fundamental principles of the embodiments illustrated and described; and while I have described my invention as applied to the driving of motor vehicles and other similar apparatus, I am aware that it is applicable to many phases of the electrical industry, and may be adapted to many and varied purposes. My invention is not, therefore, to be limited to the particular embodiments illustrated and described, nor to be limited in its application to the fields specifically referred to in the foregoing description of its construction and operation.

In describing my apparatus and its operation I have made use of certain curves illustrating certain of its operating charac- 'teristicst These curves merely illustrate the operating characteristics of a combination vof a certain power dynamo and regulating dynamo and certain auxiliary control apparatus, and it must be clearly understood that by changing the characteristics 'of these various elements the operating characteristics of the entire apparatus can be varied between wide limits. It is therefore to be clearly understood that my invention is not limited in any way except by the scope of the appended claims.

Having thus described my invention, what I claim is: f

1. The combination with 'a m r comprising a series field winding and shunt field winding, of a regulating dynamo connected in series with said shunt field winding to oppose the potential impressed on said shunt field winding, a field winding for said regulating dynamo connected in shunt to said motor shunt field winding, an adjustable` varying said ratio.

The combination with a motor having a shunt field winding, of a regulating dynamo connected in series with said shunt field winding to oppose the potential impressed on said shunt field winding, a field winding for said regulating 'dynamo connected in shunt to said mot/0r shunt field winding, an adjustable rheostat Vconnected in series with saidv regulating dynamo field Winding, a second field Winding` for said regulating dynamo opposing said firstnamed regulating dynamo field winding, the said second field winding being connected in shunt to said motor shunt field winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means for varying the i tio. i

. 3. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series with said shunt field winding to oppose the potential impressed on said shunt field' winding, a field winding for said regulating dynamo connected in sliu'nt to said motor shunt field winding, an adjustable rheostat connected in series with said regulating dynamo field winding, a second field winding for said regulating dynamo opposing said firstnamed regulating dynamo field winding, means for causing said motor and dynamo to rotate at spec-ds bearing a constant ratio to each other, and means for varying the ratio. Y

4. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series with said shunt field winding, to oppose the potential impressed on said shunt field winding, a' field winding for said regulating dynamo, means for supplying exciting current to said regulating dynamo field winding at a rate constantlyproportional to the flow of current in said shunt field winding, an adjustable rheostat connected in series with said regulating dynamo field winding, 'means for causing said motor and dynamo to rotate at s'fpeeds bearing a constant ratio to each other, and means for varying said ratio.

5. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series with said shunt field Winding to oppose the potential impressed on said shunt field winding, a field Winding for said regulating dynamo, means for supplying current to said regulating dynamo field winding at a rate constantly proportional to the fiow of current in Said shunt field winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means for varying said ratio,

6` The. combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding y 7. The combination with a. motor having a field winding, of a regulating dynamo connected in series with said field wlnding to form a field winding circuit, means for impressing a constant voltage on said field winding circuit to oppose the counter-elec-- troinotive force of said regulating dynamo, said regulating dynamo having a magnetic field circuit, means for causing said regulating dynamo to operate at a speed bearing a constant ratio to the speed of said motor, selective means for changing said ratio, and means for initially increasing the flux in said regulating dynamo magnetic field circuit to increase the speed of said motor, and for subsequently decreasing said fiux to cause the speed of said motor to continue to increase. l

8. The combination with a .n'iotor having a shunt field winding, offa regulating dynamo connected in series with said shunt field winding to oppose the potential impressed on said shunt field Winding, a magnetic field circuit for said regulating dynamo, adjustable means for creating a fiux in said magnetic field circuit which initially increases to increase the speed of said motor, and subsequently decreases to further increase the speed of said motor, and means for varying the rate at which said flux increases and decreases with respect to the speed of said motor.

9. The combination with a dynamo having a field winding, 0f means for Yimpress- Eing a voltage on said field winding, a reguiating dynamo connected in series with said ,ld winding, andopposing the voltage impressed thereon, said regulating dynamo having a magnetic field circuit, means for creating a magneto-*motive force for creating a magnetic flux in said magnetic field circuit, other means for varying said magneto-motive force, means Ifor causing said regulating dynamo Ato operate at a speed bearing a'constant ratio `to tlf speed of said first-named dynamo, and means for varying said ratio.

1f). The combination with a motor havin a commutating field winding and a shunt field winding, of a regulating dynamo connected in series with said shunt field `winding -to oppose 'the potential impressed on said shunt field Winding,afield Winding for said regulating dynamo connected in shunt to said motor shunt field Winding, an adjustable rheostat connected in series with said regulating ydynamo field Winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means vfor causing said motor to slow down under load, comprising .a field winding forming a part of said armature circuit.

11. The combination With a motor having a shunt field winding, of a regulating dynamo connected in series with sald shunt field winding to oppose the potential impressed on said shunt field Winding, a field winding for said regulating dynamo connected in shunt to said' motor shunt field winding, an adjustable rheostat connected in series with said regulating dynamo field winding,l means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means for causing said motor to slow down under load.

12. 'The combination with a motor having a field Winding, of a regulating dynamo connected in series with said field Winding to form a field winding circuit, means for impressing 'a ,substantially constant potential on said field Winding circuit, a fied winding for said regulating dynamo, means for supplying current to said regulating dynamo field winding. at a rate constantly proportional to the rate of fiow of current through said motor field winding, an adjustable rheostat connected in series with said regulating dynamo field Winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means forming a part of said motor and responsive to increase in load, for reducing the speed of said motor.

13. The combination with a motor having a magnetic field circuit and a field Winding for said magnetic field circuit, of a regulatin dynamo connected in `series with said fie d Winding to'form a field Winding circuit, means said field winding c reuit 1n opposition to for im ressing a potential on y `the counter-electromotive force of said regwinding at a rate constantlyproportional to the rate of flow of current in said motor field winding, an adjustable rheostat connected in series with said regulating dynamo field winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and other means responsive to increase in load, for increasing the flux in said magnetic field circuit.

14. The combination with a motor having a magnetic field circuit, and a field winding for said magnetic field cirniit, of a regulating dynamo connected in series with said field winding w for?" a field winding circuit, means for impressing a "oltage on said field Winding circuit in opposition to the coiInter-electromotive force of said regulating dynamo, a field Winding for said regulating dynamo, means for supplying current to said field winding at a rate constantly proportional to the rate Vof flow of current in said motor field winding, an adjustable rheostat connected in series with said regulating dynamo field Winding, meansfor causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and other means responsive to increase in load for causing said motor to slow down.

l5. The combination with a motor having a magnetic field circuit and a field winding for inducing a fluxV in said magnetic field circuit, of a regulating dynamo connected in series with said field winding to form a field Winding circuit, means for impressing a substantially constant potential on said field winding. circuit, a field Winding for said regulating dynamo, means for supplying current to said regulating dynamo field Winding at a rate constantly proportional to the flow of current in said motor field winding, means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to eac-h other, and other means forming a part of said motor and responsive to increase in load for increasing the -nflux in said magnefic field circuit for reducing the speed of said motor.

13. The combination with a motor having .a field winding, of a regulating dynamo connected in series with said field Winding to form a field Winding circuit, means for impressing a substantially oo nstant potential on said field Winding circuit, a eldnrinding for said regulating dynamoy distinct from said armature circuit,rrneans for `supplying,current to said regulating dynamo field Winding at a rate constantly proportional. to the rate of flow of current through said motor field winding, means for adjusting the ratio of the current flowing in said field windings, ymeans for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other, and means responsive to increase in load, for reducing the speed of said motor.

17. The combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding, to form a field winding circuit, means for impressing a constant potential upon saidfield Winding circuit in opposition to the counter-electromotive force of said regulating dynamo, a magnetic circuit for said regulating dynamo, a field winding for said regulating dynamo for creating flux in said magnetic circuit, an adjustable rheostat con' nested in series with said regulating dynamo field winding, and means for reversing the fiux through said magnetic circuit when said motor is operating at 'substantially its lowest running speed, comprising a second field winding for said regulating dynamo, opposing said first-named regulatie dynamo field winding, the said secon field winding being connected in shunt'to said motor shunt field winding. and means for causing said motor and: dynamo to rotate at speeds Ibearing a constant ratio to each other.

18. The combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding. to form a field Winding circuit, means for imi pressing a constant potential upon said field winding circuit in opposition to the counter-electromotive force of said regulating dynamo, a magnetic circuit for said regulating dynamo, a field winding for said regulating dynamo for creating flux in said magnetic circuit, and means for reversing the flux through said magnetic circuit when said motor is operating at substantially its lowest running speed, comprising a second field windin for said regulatinr dynamo, opposing said first-named reguliiting dynamo field winding, the said second field winding being connected in shunt to said motor shunt field winding, and means for causin said motor and dynamo to rotate at speeds aring a constant ratio to each other.

19. The combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding, to form a field winding circuit. means for impressing a constant potential upon said field winding circuit in opposition to the counterelectromotive force of said regulating dynamo, a magnetic circuit for said regulating dynamo, a field windin for said regulating dynamo for creating ux `in said magnetic clrcuit, meanrI for reversing the flux thniu'ph said magnetic circuit when said motor is operating at substantially tslowest running,

speed, comprising a second field winding for said regulating dynamo, opposin said firstnamed regulating dynamo fiel Winding, andl means for causing said motor and dynamo to rotate at speeds bearing a constant ratio to each other.

20. Tho combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding, to form a field winding circuit, means for impressing a constant potential upon said field winding circuit in opposition to the counter-electromotive force of said regulating dynamo, a magnetic circuit for said regulating dynamo, a field winding for said regulating dynamo for creating flux in said magnetic circuit, means for reversing the flux through said magnetic circuit when said motor is operating at substantially its lowest running speed, comprising a second field Winding for said regulating dynamo, opposing said first-named regulating dynamo field winding, means for supplying current to said second field winding at a rate constantly proportional to the rate of flow of current in said motor field winding, and means for causin said motor-and dynamo fo rotate at speer s bearing a constant ratio to each other. 21. The combination with a motor havmg a field winding, of a regulating dynamo connected in series with said field winding to form a field winding circuit, means for impressing a constant potentiaLupon said field winding circuit in opposition to the counter-electromoti\-e force of said regulating dynamo, a magnetic circuit for said regulating dynamo, a field winding for creating fiux in said magnetic circuit, means for supplying current to said regulating dynamo field winding at a rate constantly proportional to the fiow of current in said motor field winding. and means for reversing the flux through said magnetic circuit.

22. The combination with a motor having a field winding, of a regulating dynamo connected in series with said field winding, to form a field winding circuit, means for impressing a potential upon said field winding circuit in opposition to the counterelectromotiie force of said regulating dynamo, means for reducing the opposition of said dynamo to said last named means, to zero tocause said motor to operate iit a low7 speed, and for subsequently increasing the potential across said motor field winding to cause it to operate at a still lower running speed. and means for maintaining the speed of said regulating dynamo constantly proportional to the speed of said motor.

23. The combination with a motoi` having an armature circuit and a field winding circuit. comprising a regulating dynamo. of means for impressing a potential on said fields-*winding circuit in the same direction as the voltage of saidI regulating dy celerating said motor, and means for driv? ing said regulating dynamo at a s eed constantly proportional to theA spee of said motor.

2l. The combination with a motor having an armature circuit and a field winding circuit, comprising a regulating'v dynamo, of means for impressing a potential on said field winding circuit in the same direction as the voltage of said regulatingdynamo, a field Winding for said regulating dynamo, means for supplying current to said regulating dynamo field Winding at a rate con; stantly proportional to the flow of current in said field winding circuit and means for reversing `the voltage of said dynamo.

The combination with a dynamo for functioning either as a motor or a generator, and having a shunt field winding, of a regulating dynamo, having its armature connected in series with said shunt field winding to form a field winding circuit, said field Windin circuit being connected across the termin s of said first-named dynamo and the regulating dynamo being so connected with the shunt Winding as to oppose the voltage impressed on said terminals, a field winding for said regulatin dynamo connected in shunt to a portion o said field winding circuit, and a driving connection between said dynamo and said regulating dynamo, for driving said regulating dynamo at any desired speed relative to the speed of said first-named dynamo.

26. The combination with a dynamo for functioning either as a motor or a generator, and having a shunt field winding, of a regulating dynamo having its armature connected in series with said shunt field windin to form a field Winding circuit, said fie d Winding circuit being connected across the terminals of said first-named dynamo and the regulating dynamo being so connected with the shunt field winding as to op ose the voltage -impressed on said termi, nas, a field winding for said regulating dynamo connected in shunt to a portion of said field winding circuit, and means for driving said regulating'dynamo at various speeds relative to the speed of said firstnamed dynamo, the said last-named means embodying means for maintaining a constant proportionality between the speeds of the two dynamos at whatever speed` they aredriven. v

27. The combination with a dynamo for functioning either as a motor or a generator, and having a field winding, of means for impressing a varying voltage upon said winding, comprising a second dynamo connected in series with said field winding, and means for driving said second dynamo at speeds bearing a constant ratio to the speed of said first-named dynamo, and means for varying said ratio.

28. The combination with a dynamo for functioningeither as a motor or a generator, and having a, field Winding energlzed by a source of current, of a second dynamo having its armature connected with said field winding and said source of current to regulate the flow of current through said field winding, means for causing said second dynamo to operate at speeds bearing a constant ratio to the speed of said first named dynamo, `and manuell controlled means for varying the speed e said second dynamo relative to the speed of said first-named dynamo electric machine.

29. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series` with said shunt' field winding, so as to oppose voltage imposed on said shunt field winding, means for driving said regulating dynamo at a plurality of different speeds, each speed having a constant ratio to the speed of said motor, and manually controlled means for cont-rolling said last-named means.

30. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series With said shunt field winding, so as to oppose voltage imposed on said shunt field winding, means for driving said regulating dynamo at a plurality of different speeds, each speed having a constant ratio to the speed of said motor, and means for varying said ratio.

31. The combination with a motor having a shunt field winding, of a regulating dynamo connected in series with said shunt field winding, so as to oppose voltage imposed on said shunt field winding, and meansfor driving said regulating dynamo at a plurality of different speeds, relative to the speed of said motor, each speed having a constant ratio to the speed of said motor.

The combination with a power dynamo having a shunt field winding, of a regulating dynamo having its armature connected in series with the shunt field Iwinding of said power dynamo, so that the voltage gew erated by said armature opposes the voltage impressed on the shunt field of said power dynamo, the field Winding of said regulating dynamo being connected in parallel with the shunt field winding of said power dynamo` an adjustable resistance connected in series with the field of said regulating dynamo, and means for driving said regulating dynamo at a Speed bearing a constant proportionality to the speed of said power dynamo.

33. The combination with a power dynamo having a shunt field winding, of a-yregulaty` ingl dynamo havin its armature connected in series with sai shunt field winding so

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