US962334A - Alternating-current motor. - Google Patents

Description

V. A. FYNN. ALTERNATING CURRENT MOTOR.

uruoumn FILED JULY 2, 1909.

962,334. Patented June 21, 1910.

5 SHEETS-SHEET 1.

WITNESSES: INVENTOR f, Vjlre A.Fynn

v. A. FYNN. ALTEBNATING CURRENT MOTOR.

APPLICATION FILED JULY 3, 1909.

Patented June 21,1910.

5 SHEETS-SHEET 2.

WIT/(E8858: IN VE N T 0/? V.A.FYNN. ALTERNATING GUBBENT MOTOR. APPLICATION FILED JULY 3, 1909.

Patented June 21, 1910.

5 BKEBTB-BHEET 3.

WITNESSES:

ORNEYS V. A. FYNN.

ALTEBNATING CURRENT MOTOR. APYLIOATIOIYIILED mm a, 1909.

Patented June 21, 1910.

6 SERIES-SHEET 4.

IT rimm n- I mmvms I I Li. W 21 51 V. A. FYNN. ALTERNATING CURRENT MOTOR. APPLIOATIOH nLnn JULY 3, 1909.

Batented June 21, 1910.

' 58KEBT8-8HEET 5.

WITNESSES: INVENTOR ig Vglere AiFynn PATENT OFFICE.

UNITED STATES VALIJBE ALFRED. FYNN, OF LONDON, ENGLAND.

ALTERNATING-CURBENT MOTOR.

To all whom it may concern: I

Be it known that I, VALisnn ALFRED FYNN,

a subject of the King of England, residing at London, En land, have invented a certain new and usefu Alternating-Current Motor,

of which the following is such a full, clear, and exact description as will enable any one skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, forming part of this specification.

' My invention relates to means for starting and operating single phase induction motors in which the in need winding responsible for the operation of the motor is permanently closed on itself independently of any commutator. It is known that motors of this type have distinct mechanical advantages and good operating characteristics but are difficult to start with a powerful torque and with a small current or in other words with a large torque per ampere.

One object of my mventionis to provide such means for startingsaid motors. with a large torque per ampere as will not make it necessary to dimension or dispose the secondary working winding permanently closed on itself with any other objects in View but those of highest effectiveness and eiiiciency under normal running conditions.

Other objects of my invention are to avoid the use of all automatic short-circuiting devices inside the rotor, to provide means for compensating such machines and to generally improve their characteristic roperties both at starting and under norma working conditiona I achieve iny objects by providing my motor with a rotor having a permanently short-circuited winding extending over all the rotor laminations and a pluralit of commuted. windings longitudinally isplaced and extending over a part only of the rotor laminations, by conveying a working current to each commuted winding and neutralizing the effects of such currents on the shortcircuited winding, by producing a motor flux threading each commuted winding and adapted to produce a starting torque with the ampere turns due to the correspondin workin current while neutralizing the e fects 0 said motor fluxes on the short-circuited winding and by inducing currents in Specification of Letters Patent. P t t d J n 21, 1910, Application filed July a, 1909; Serial No. 505,779.

the short-circuited winding either at the moment of starting or after the motor has reached a sufficient speed, thus limiting the speed of the machine and converting same into a self-excited shunt induction motor. and finally by impressing on at least one of the commuted windings, preferably after the motor has reached a sufficient speed, an E. M. F. of suitable phase for improving the power factor 2'. e. compensating the motor. Thus in my preferred form of motor I provide a permanently short circuited working winding on the induced or secondary member together with two commuted windings on that member and so Wind the inducing or primary member that in one connection or combination of its windin s the secondary working winding permanent y closed on itself will not carry any currents, whereas in another connection or combination of the windings on the inducing member the secondary working winding permanently closed on itself will have currents induced in it which will close in that winding without the help of a commutator. first connections are used at starting, the second are used in normal operation. I further so connect or combine the windings disposed on the primary member that the motor may start as a series induction, as a series or a shunt conduction motor. In normal operation one or more of the commuted windings may in some modifications, also carry working currents thus contributing to 'the useful torque.

In all induction motors there is a trans former flux which conveys energy from the inducing to the induced member, and a motor fiux which produces torque with the current induced in the secondary. In conduction motors there is sometimes a fluxdue to the working current in the armature and there is always a motor flux. I preferably dispose my windings in such a manner that neither of these fluxes will produce any currents in the permanently short-circuited secondary working winding at starting and before the primary connections have been altered from the starting to the running connections. I may make the necessary change in the connections automatically or by hand. If an automatic, for instance a centrifugal,

device is used it can be placed outside the The motor; it can therefore always be made easily accessible, can be kept in good con: dition and can be quickly repaired 'or replaced. When the machine has reached a sufiicient speed I can make use of one or more of the commuted windings for the purpose of compensating, i. 6'. improving-the power factor of the machine. By suitably interconnecting the commuted windings I can cause a working current to flow through these windings independently of the commutator, thus relieving the latter and obviating all danger of sparking.

In describing some ways of carrying my invention into practice I will refer to the accompanying diagrammatic drawings of two-pole motors wherev Figure 1 shows a motor in which the two commuted windings are interconnected, which is capable of being compensated and is arranged to start as a separately excited series induction machine with the motor field winding disposed on'the inducing member. Fig. 2 indicates the mechanical disposition of the motor parts for the machine shown in Fig. 1. Fig. 3 is a motor capable of being compensated and arranged to start as a separately excited series induction motor with the'motor field winding disposed on the induced'member. F ig. 4 is a motor capable of being compensated by means of a transformer independent of the motor and arranged to start as a self-excited series induction motor in which'the motor field winding is disposed on the induced member. Fig. 5 is a motor capable of being compensated and arranged to start mainly as a neutralized series conduction motor. Fig. 6 is a motor capable of being compensated and arranged to start as a shuntconduction motor.

Fig. 1 shows a motor with two longitudinally displaced primary or stator windings 7 and 8 disposed along parallel axes,. ar-

- ranged to be connected in parallel and to be fed from the mains 1, 2 by way of a transformer having a primary 3 and a secondary 4. The movable contact 5'on the latter controls the magnitude of the. E. M. F. impressed on the circuit containing 7, whereas 6 controls the magnitude of the E. M. F. impressed on the circuit containing 8. An automatic switch '9, here shown as being of the centrifugal type, is adapted to be geared to the motor shaft for instance by means of the pulley 10.- When'the motor isat rest the contact levers 11 and 12 of.9, which are insulated from the body of 9, are in the position shown; after the motor has reached a sufiicient speed these levers leavecontacts 15, 20 and 17, 14 and bridge the contacts 13, 19 and 18, 16. It is best to so design 9. as to cause these levers to snap from the starting to the running position. The secplaced and similarly interconnected com muted windings 34, 35. The first is shortcircuited by means of the brushes 36, 37

' along an axis approximately coinciding with that of 7, the second is short-circuited by the brushes 40, 41 along an axis approximately coinciding with that of 8.

Each commuted winding carries exciting brushes 38, 39 and 42, 43; these exciting brushes are displaced by about 180/n degrees with respect to the correspondin shortcircuited brushes or with respect to t e axes of 7 and 8 respectively. The letter 1:. stands throughout for the number'of poles of the motor. The exciting brushes 38, 39 can be connected to the compensating winding 54 by means of the reversing switch 76. The

exciting brushes 42, 43 can be connected to the compensating winding 55 by means of 77. The direction of the com ensating E. M. F. is controlledby 76, 77, t ese switches being closed in the one or the other direction according to the direction of rotation and after the motor has reached a suflicient speed. Switch 74 controls the direction of the current through the'motor field windings 66, 67 dis osed on the inducing member. This switch, therefore, controls the direction of rotation of the motor. Switch 71 is adapted to cut the stator field windings 66, 67 out of circuit. At starting all switches are in the positions shown. WVith reference to the shortcircuited winding 24, 25, the inducing winding 8 magnetizes in a direction opposite to that of the magnetization due to 7 and the movable contacts 5 and 6, if such are used, are preferably so adjusted that the E. M. F.s induced in 24 and 34 are of equal magnitude to those induced in 25 and 35 respectively. At starting the primary circuit is as follows: from point 52 of 4 to switch 74 through 66, 67 in one or the other direction, out through 71 and 74 to point 51 from there through 7 and 5 back to 4 and also from 51 through 17, l1, 14 to 8 and through 15, 12, 20 and 6 back to 4.

Since the magnetizations due to 7 and 8 are of op osite'direction with respect to 24,

magnitude then no current will flow by way of the interconnections between 24 and 25, i, 6. there will be no current from 28 to 29, 26 to 27, 56 to 57 and so; on. The effect of the transformer fluxesiion the short-circuited working winding thus eliminated.

The E. M. F s induced in the commuted windings 34, 35 will, however, determine a local current in each of them. These local currents will close by way of the short-circuited brushes 36, 37 and 40, 41 respectively.

The current in 34 will be of opposite direction to that in 35 and in order that-these two windin shall give torques in the same direction t e primary current conducted through 66 for the purpose of generating a motor field adapted to interact with the current induced in 34 must be conducted through 67 in a direction opposed to that in which it is conducted through 66. This is clearly shown in Fig. 1. This motor starts as a separately excited series induction motor, the longitudinally displaced stator windings 66, 67 doing duty as motor field windings. Since the fluxes due to 66 and 67 are of opposite direction with respect to 24, 25 their efiect on the short-circuited working winding 24, 25 will be nil provided the magnitude of these fluxes is approximately the same, nor will these fluxes cause any currents to flow in the connections between 34 and 35. Since these fluxes are due to the same current it is only necessary that the number of turns in 66, 67 and the relative space position of 66 to 24, 34 and of 67 to 25, 35 as well as the relative brush positions be sensibly the same in order that this desired condition may be practically fulfilled. It is seen that the short-circuited working winding 24, 25 is quite idle at startmg.

As the motor gathers speed the E. M. F.

impressed on 8 may, if desired, be gradually diminished down to .Zero, when .8 will be short-circuited. After that the E. F. impressed on 8 may be gradually increased in the opposite direction. In most cases it will be quite suflicient to simply reverse the current through 8 after the motor has reached a sufliciently high speed. In Fig. 1' this is achieved by means of the automatic switch 9. As soon as 8 has been reversed then the combined windings 24, 25 and 34, 35 act just like the ordinary short-circuited secondaries of a self-excited single-phase shunt induction motor of ordinary construction, both these combined windings becoming working windings. The brushes could.

now all be lifted oil the commutators but I prefer to leave all the brushes on the commutato'r and to close the circuit of the exciting brushes so as'to include a com ensating E. M. F. in the exciting circuits 0 either 34' or 35 or of both, thus making use of 34,

35 for compensating purposes as well as for carrying part of the load current. This compensation is achieved in Fig. 1 by closingswitches 76 and 77 in the proper direction. It is preferred, after the motor has reached a sufiiciently high speed, to cut' 66 and 67 out of circuit by means of 71. The windings 7 and 8 are shown connected in parallel but it is obvious that they can also be connected in series and if it were not for the fact that the current through one of them must in this case be capable of being reversed they could be replaced by a single winding. A modified construction embodying this idea is shown in Fig. 6.

In order to provide for an easy accommodation of the longitudinally displaced stator and rotor windings the motor laminations can be split up into two groups in the manner indicated in Fig. 2. The two groups of stator laminations are shown at 44 and 45; the two longitudinally displaced stator windings at 7 and 8; the two compensating windings at 54, 55; the field windings at 66, 67. The two groups of rotor laminations are shown at 46, 47. They are mounted on the same shaft and are spaced to correspond to 44 and 45. The two longitudinally displaced commuted windings are shown at 34, 35; their respective commutators at 48, 49 and their interconnections are indicated at 75. In Fig. l the working winding 24, 25 permanently closed on itself independently of a commutor has een;

connected windings are electrically equivalent to a single winding, for instance to a squirrel cage such as shown in Fig. 2 and wound straight through both groups of the rotor laminations. This squirrel cage has been designated by the two numerals 24, 25 in Fig. 2 so as to draw attention to the fact that it is the equivalent of the two interconnected windings 21, 25'of Fig. 1. In

practice it will generally be more advantageous to make use of a squirrel cage construction for the working winding permanently closed on itself. It is immaterial whether the two groups of laminations 44, 45 are inclosed within the same or within separate frames. It is, however, necessary that the two groups of rotor laminations be rigidly coupled and that the part\of the short circuited working winding disposed on one group of rotor laminations be electrically connected at a plurality of points to that part of this same winding which is disposed on the other roup of rotor laminations. The stator windings 7, 8 need'not be disposed along parallel axes. The windings disposed on 44, 46 have been shown in Figs. 1 and 2 as 2 pole windings, those disposed on 45, 46 have also been shown as 2 pole windings, but this is by no means neces sary although it is the preferred arrangement. The number of poles of the windings disposed on one group of stator and rotor laminations may differ to any desired extent from that of the windings disposed on another group of such laminations.

In Fig. 3 the two longitudinally displaced stator windings 7, 8 are directly connected to the mains l, 2, the reversing switch 53 is arran ed to control the direction of the current t rough 8. The inducing windings 7 and 8 magnetize in opposite directions at starting but the current through 8 is reversed after the motor has reached a suffi- .cient speed. Accordingly the rotor working winding permanently closed on itself is so arranged that the E. M. F.s induced therein oppose each other when 7 and 8 magnetize in opposite directions and are in the same direction when 7 and 8 magnetize in the same direction. This is diagrammatically indicated in Fig. 3 by connecting point 28 to 29, point 26 to 27, point 32 to 33 and point 30 to 31. The motor field is produced by connecting the commuted windin s 34, 35 in series relation with the inducing stator windings. This is achieved in Fig. 3 by connecting point 51 to brush 38, brush 39 to brush 43 and brush 42 to the main 2. The line current is thus taken through the rotor along an axis displaced by about 180/n degrees with resepct to the axes of 7 and 8. Since the current induced in 34 at starting is of opposite direction to that induced in 35 then the exciting current must be taken in opposite directions through34 and 35 in order to secure torques in the same direction. The commuted windings 34, 35 are not interconnected in this case, but they are nevertheless active at starting and in normal operation. All the currents flowing in these windings now close by way of the commutator only even in normal operation. When .34, 35 are not interconnected then a common source of compensating E. M. F. can be made use of. In this case the exciting brushes on both windings are connected to part 23 of winding 7 when switches 21 and 22 are closed and this part 23 of 7 then acts as compensating windin Switches 21, 22 are preferably closed a r the motor has reached a sufficient speed and the current through 8 has been reversed.

In Fig. 4 the windings 7, 8 are arranged to magnetize in the same direction at starting. The commuted windings 34, 35 are not interconnected although they can be interconnected if desired. The interconnections of 24, 25 are also altered. Thus point 28 is connected to point 33 instead of 29 and so on. If 34 and 35 are to be interconnected then point 56 should be connected to 61 and so on. The starting is accomplished by displacing the short-circuited brushes 36, 37 from the axis of 7 and the short-circuited brushes 40, 41 from the axis of 8. Since the torques due to 34 and 35 are to add these displacements should be in the same direction, irrespective of the relative direction of the magnetization due to 7 and 8 respectively, and the degree of displacement should be such in each case that the motor field due to 35 equals the motor field due to 34, thus eliminating the action of those motor fields on the short-circuited working winding 24, 25 at starting. After the motor has reached a suflicient speed the current through 8 is reversed and if phase compensation is desired then switches 21, 22 are closed thus impressing compensating E. M. F.s on the exciting brushes 38, 39 and 42, 43. These E. M. F.s are here derived from a shunt transformer, the primary 68 of which is connected across the mains 1, 2. This transformer has two independent and regulatable secondaries 78, 79. If 34, 35 are not interconnected then one secondary is sullicient. The short circuited brushes may be moved so as to coincide with the axes of 7 and 8 after the motor is up to speed. The direction of rotation can be reversed by moving the shortcircuited brushes beyond the axes of 7 and 8. If the short circuited working winding 24, 25 were for instance of the squirrel cage type then one and the same bar would have to pass the two groups of rotor laminations through slots displaced by about 360/71, degrees in order to correspond to the interconnections between 24 and 25 which are shown in Fig. 4. 4

The motor shown in Fig. 5 carries two inducing windings 7 and 8 connected in parallel. The two parts 24 and 25 of the shortcircuited working winding are sointercohnected that this winding will be responsive to induction effects due to 7 and 8. In practice a squirrel cage such as shown in Fig. 2 would be used instead of the interconnected windings 24, 25. The actual starting circuit consists of the neutralizing windings 99, 98, the commuted windings 34, 35 and the motor field windings 66, 67. All the elements of this starting circuit are connected in series, the commuted windings being included by way of the brushes 36, 37 and 40, 41 respectively. At starting switch 74 stands on points 101, 103 and switch 100 can be left open. The machine starts as a neutralized series conduction motor and the torque and speed may be varied by adjusting the movable contact 6 on the secondary 4 of the transformer with the primary 3 feeding the motor from mains 1,2. when a suflicient s eed has been reached switch 100 is close thus bringing the short-circuited rotor working winding into play and converting the machine into a self-excited i-shunt induction motor. The starting circuit may now simply be opened thus rendering the commuted windings idle or these maybe made use of to compensate the machine. One way of achieving this is shown in Fig. 5 and consists in moving 74 on to points 102 and .104. The motor field windings 66, 67 now act as compensating windings, the compensating E. M. F.s being induced therein by 7 and 8. The whole or part only of the motor field windings may be used for compensating purposes. Since the currents flowing through 34- and 35 at starting flow in relatively op osite directions than the fluxes they would set up will not induce currents in 24, 25 and the neutralizing windings 99, 98 can be omitted if desired. Switch 100 can be closed at starting and although this will reduce the torque per ampere yet the fluxes due to 7 and 8 will not otherwise interfere with the starting operation and will prevent the motor from racing. The two windings 7 and 8 can of course be replaced by a single one embracing both groups of stator-laminations.

In Fig. 6 the stator carries three windings. One of these embraces both groups of stator laminations and is shown at 97. It takes the place of the two windings 7 and 8 of Fig. 5 whether the latter be connected in series or in parallel. Thewindi'ngs 24, 25 are so interconnected as to ,form a shortcircuited winding responsive to inductive effects due to 97. The stator windings 117 and 118 are adapted to produce fluxes which link with 34 and 35 respectively and are conductively connected. to these commuted windings by way of the brushes 36, 37 and 40, 41 respectively. At starting switch 119 stands .on points 115, 116 thus connecting 117 and 118 in parallel and to the supply. The motor starts as a shunt conduction machine owing to the interaction of the fluxes due to 117 and 118 threading 34 and 35 and the ampere turns in 34 and 35 due to the currents derived from 117 and 118 and'conducted through 34 and 35 respectively by way of the brushes. The starting torque can be regulated at 120 and 121. When a sutficient speed has been reached switch 119 is thrown on to point 114 whereby 117, 118 are disconnected from the supply and 97 is connected to the mains 1, 2. The short-circuited working windings 24, 25 now comes into play. The flux due to 97 also induces E. M. F.s in 117 and 118. These E.M.F,'s are made use of for compensating the machine and no further change of connections is required to achieve this purpose for the commuted windings are already connected.

to 117 and 118 byway of the brushes 36, 37 and 40, 41. The magnitude of the compensating E. M. F .s can be adjusted at 120 and 121. If 97 is connected to the supply at starting then the motor will never exceed its normal speed but the torque per ampere at starting will be somewhat reduced particularly if the full line voltage is impressed on 97 from the very first.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In an alternating current motor, the combination with a stator, of a laminated rotor provided with a permanently shortcircuited winding and two commuted windings, said short-circuited winding extending over all the rotor lamirations and each.

winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations.

. 3. In an alternating current motor, the combination with a stator provided with a plurality of windings, of a rotor containing two longitudinally displaced groups of laminations and provided with a permanent-1y short-circuited winding and two connnuted windings, said short-circuited winding extending over both groups of rotor laminations and each of said commuted windings extending over only one group of rotor laminations.

4.- In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, a laminated rotor provided with a permanently short-circuited winding and two commuted-windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations.

5. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, each group being provided with a main winding, a laminated rotor provided with a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations.

6. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means 'for Cit producing a main flux through each group of laminations, two auxiliary windings, one of which is coaxially disposed with reference to the main flux through one group of laminations, a laminated rotor provided with a permanently short-circuited winding and two commuted windings, said shortcircuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations. I

'7. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, an auxiliary winding coaxially disposed with reference to themain flux through one group of laminations, a laminated rotor provided with a permanently sho'rt-circuited winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings ex tending over a part only of the rotor laminations.

-8. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, two auxiliary windings, one of which is coaxially disposed with reference to the main flux through one group of laminations, a laminated rotor provided with a permanently short-circuited. winding and two commuted windings, said shortcircuited winding extending over all'the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations, and separate means for directing the flow of current inv each of the commuted windings.

9. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, an auxiliary winding coaxially disposed with reference to the main flux through one group of laminations, a laminated rotor provided with a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations,.and separate means for directing the How of current in each of the commuted windings,

10. In an alternating current motor, a stator' containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, a laminated rotor provided with a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations, and separate means for directing the flow of current in each of the commuted windings.

11. In an alternating current motor, the combination with a laminated rotor vided with a permanently short-circulted winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a part only of the rotor laminations, of two stator windings longitudinally displaced from each other and adapted to produce magnetic fluxes through the rotor, said magnetic fluxes being of such position and direction at starting that the permanently short-cin cuited winding will be inoperative.

12. In an alternating current motor, a rotor containing two longitudinally displaced groups of laminations and provided with a permanently short-circuited winding extending over both of said groups and two commuted windings each extending over only one of said groups, and means for producing a transformer flux through each group of rotor laminations and means for producing a motor flux through each group of rotor laminationsat starting.

13. In an alternating current motor, a rotor containing two longitudinally displaced groups of laminations and provided with a permanently short-circuited winding extending over both of said groups and two commuted windings each extending over only one of said groups, said commuted windings being interconnected at a plurality of points, and means for producing a transformer flux through each grou) of rotor laminations and means for pro ucing a motor flux through each group of rotor laminations at starting.

14. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, a rotor containing two lon-,

gitudinally displaced groups of laminations and provided with a permanently short-circuited winding and two.commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windings extending over only one' group of laminations.

15. In an alternating current motor a stator containing two longitudinally placed groups of laminations, means forproducing a main flux through each group of laminations, two auxiliary windings, one of which is coaxially disposed with reference to the main flux through one group of laminations, a rotor containing two longitudinally displaced groups of laminations and provided with a permanently short-circuited \vindin and two commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windings extending over only one group of laminations.

16. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, means for producing a main flux through each group of laminations, an auxiliaryv winding coaxially disposed with reference to the main flux through one group of laminations, a rotor containing two longitudinally displaced groups of laminations, and rovided with a permanently sliort-circuite winding and two commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windings extending over only one group of laminations.

17. In an alternating current" motor, a stator containing two longitudinally dis placed groups of laminations, eachgroup being provided with a main winding, a rotor containing two longitudinally displaced groups of laminations and provided with a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windings extending over one group of'laminations, and brushes for .conductively conveying a current to each commuted winding along an axis displaced from the axis of the corresponding main stator winding.

18. In an alternating current motor, a stator containing two longitudinally displaced groups of laminations, each group being provided with a main winding, two

auxiliary windings, one of which is coaxially disposed with reference to one of said main windings, a rotor containin two longitudinally displaced groups of aminations and provided with a permanently shortcircuited windin and two commuted windings, said short-circuited winding extendin over both grou s of laminations and each 0 said commute windings extending over only one grou of laminations, and brushes for conductive y conveying a current to each commuted winding along an axis displaced from the axis of the corresponding main stator winding. v

19. In an alternating current motor, a stator containin two longitudinally displaced grou s 0% laminations, each group being provi ed with a main winding and two auxiliary windings, one ofrwhich is coaxially disposed with reference to said main winding, a rotor containin two longitudinally displaced groups of aminations and provided with a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windin extending over only one group of laminations, brushes for conductively conveying a current to each commuted winding along an axis displaced by approximately 180/n degrees from the axis of the correspondin brushes for s ort-circuiting each commuted winding along another axis.

20., In an alternating current motor, a stator containing two longitudinally displaced ,groups of laminations, each group being provided with a main winding, a rotor containin two longitudinally displaced groups 0 laminations and provided with a permanently.short-circuited winding extending over both groups of laminations and each of said commuted windings extending over only one group of laminations, brushes for conductively conveying a current to each commuted winding along an axis dis placed by approximately 180/71, degrees from the axis of the corresponding stator winding, and brushes for short-circuiting each commuted winding along another axis.

21. In an alternating current motor a stator containing two longitudinally isplaced groups of laminations, each group being provided with a main winding, a rotor containing two longitudinally displaced groups of laminations and provided with a a permanently short-circuited winding and two commuted windings, said short-circuited winding extending over both groups of laminations and each of said commuted windings extending over only one group of lami-i nations, and means for reversing the current through one of the main stator windings.

22. In an alternating current motor, a stator containin two longitudinally displaced groups 0 laminations, each group being provided with a main winding and two auxiliary windings, one of which is coaxially disposed with reference to said main winding, a rotor containing two longitudinally spaced groups of laminations and provided with a permanently short-circu1ted main stator winding, and

winding and two commuted windings, said short-circuitedwinding extending over both groups of laminations, brushes for conductively conveying a current to each commuted winding along an axis displaced by approximately ISO/n degrees from the axis of the a corresponding main stator winding, brushes for short-circuiting each commuted winding along another axis, and automatic means for reversing the current through one of the main stator wmdin 23. In an a l ternating current motor, the combination with a stator, of a laminated .rotor. provided with a permanently shortcircuited winding and two commuted windings, said short-circuited winding extending over all the rotor laminations and each of said commuted windings extending over a art only of the rotor laminations and means or impressin a compensating E. M. F. on at least one o the commuted windings.

24. In an alternating current motor, a rotor containin two longitudinally displaced groups 0 laminations and provided with a permanentl short-circuited winding extending over bot of said groups and two commuted windings each extending over only one of said groups, means for producving a transformer flux through each group of rotor laminations and means for producing a motor flux'through each group of rotor laminations at starting, and .means for impressing a compensating E. M. F. on at least one ofthe commuted windings.

In testimony whereof I have hereunto set my hand and affixed my seal in the presence of the two subscribing witnesses.

VALERE ALFRED FYN N. [1. s.]

Witnesses:

ELIZABETH BAILEY, E. E. HUFFMAN.

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