Патент USA US2403665код для вставки
July 9, 1946'. 2,403,665 J. D. LEWIS ELECTRIC MOTOR " Filed July 7, 1943 4 Sheets-Sheet 1 .wE N mwmmam3avanMN.2 \( .X W43 M BY INVENTOR ATTORNEY July 9, 1946. _ J. D. LEWIS 2,403,665 ELECTRIC MOTOR Filed July 7, 1943 LL11” 4 Sheets-Sheet 2 31 st 25% 255 2J2 2>‘\ 54 3 35 sié7lv TM 13 M kw INVENTOR ATTORNEY July 9, 1946. 2,403,665 J. D LEWIS ELECTRIC MOTOR Filed July 7, 1945 _i.~TF cEmoieoa°comon?m05moQ0w00%nQQQa000uam?w00k5ER_no;om?coom03w“m0oo:m: 4 Sheets-Sheet 5 IIll 0cc0o002=05O09coocomO08mconoR00cwb00%n.09m002om009comconwm“: 00‘ /IIl 09umon0Vumo_3%0mm mm;AH.‘ L W E NTO R v‘ Aw O D“ N g July 9, 19.46. 2,403,665 J. D. LEWIS ELECTRIC MOTOR F i l e d J H 1 V. 7. l 9 I ' sI a%A1Il|LR.K? 2ID. M.,-\H%=@1w lI5kEuNim|AqléIa?. GHi.AL3“ 42.|3lI 2|Y lNm|Iula1|=»k|EmT?l“iH.ylm‘T Aéw.l? iq 6l|1MIH?§Wn\|ui5l?méd.%Im|W=RHl%-n1u|N9 0I1.%?}; H l?nullll Fl l.Mw lIll? nlLHR. |Ilc1|lI I|lI 0/.I 5I|RHQ |lg1¢¥? 0/. F!. CV. 6 ".50 Y. 0AU mu . Iw/E ATTORNEY Patented July 9, 1946 2,403,665, UNITED s'rA'rEs PATENT OFFICE 2.403.665 ELECTRIC MOTOR Jacob Daniel Lewis, Yonkers. N. Y., asaignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application July 7, 1943, Serial No. 493,792 9 Claims. (Cl. 172-280) , 1 2 I The invention relates to electric motors. In many buildings, the supply of electric power to the building is polyphase alternating current. The ratio or the number of poles productd on al ternating current excitation to the number pro duced on direct current excitation is such as to It is of advantage in many instances of industrial ‘case an amount of current ?ow through the motor applications in such buildings to utilize 5 armature conductors su?icient to cause opera polyphase alternating current motors. In some of tion oi’ the motor as a polyphase induction motor for the particular duty to which it is applied. these instances, it is desirable to provide motors which may be operated at different speeds. For Since the speed of the motor operating as a direct example, in elevator installations, it is desirable current motor is dependent upon the voltage im to provide one speed for full speed operation of 10 pressed on the armature, the number of armature the elevator and another speed slow enough for conductors, and the ?eld strength, by proper the elevator to make accurate stops at the land choice of these factors different speeds may be ob ings. This is especially the case where levelling tained. Thus the motor may be caused to run mechanism is provided for bringing the car to as a direct current motor faster or slower or at the landing level in case it underruns or over 15 the same speed as when operated as a polyphase runs a landing in stopping, induction motor. However, as the invention is The principal object of the invention is to pro especially applicable to elevator hoisting motors, vide a motor which may be operated at full speed it will be described as applied to such motor with as 9. polyphase alternating current motor and the motor operated as a polyphase induction mo which may also be operated at a very slow speed. 20 tor for fast speed operation and as a direct cur-' The invention involves a motor which may be rent motor for slow speed operation. operated as a polyphase alternating current mo Features and advantages of the invention will . tor and also as a direct current motor. In car ‘ be apparent from the above statements, the de rying out the invention according to the arrange scription which follows and appended claims. In the drawings: ment which will be described, the stator or ?eld winding of the motor is arranged for connection Figure 1 is a developed diagram of the stator to a source, of polyphase alternating current or to winding of a motor embodying the invention; a source of direct current. It is wound so that Figure 2 is a simpli?ed schematic wiring dia when certain points thereon are connected to the gram of the stator winding shown in Figure 1; Figure 3 is a magnetomotive force diagram for direct current source it acts as a direct current 30 ?eld winding to provide a stationary ?eld of a the coils of the stator winding of Figure 1; certain‘ number of pairs of poles and so that Figure 4 is a resultant ?ux diagram for the when certain points thereon are connected to the same; polyphase alternating current since it acts as a Figure 5 is a developed diagram of the rotor or polyphase alternating current stator winding to 35 armature winding of a/motor having the stator provide a rotating ?eld of a di?erent number of pairs of poles. The rotor or armature of the motor is provided with a commutator. It is wound for the winding of Figure 1; , Figure 6 is a simpli?ed wiring diagram in “across-the-line" form of a control system for a number of poles provided by the field winding motor, having the windings of Figures 1 and 5, when connected to the direct current source and 40 utilized as an elevator hoisting motor; and has equalizers connecting points having no differ Figure SS is a key diagram for Figure 6 show ence in electrical potential. Thus, when the ?eld ing the electromagnetic switches in spindle form winding is connected to the direct current source with the contacts and coils arranged on the spin and the brushes for the commutator are also con dles in horizontal alignment with the correspond nected to a direct current source, the rotor acts 45 ing contacts and coils in the wiring diagram. as a direct current armature and the motor runs An embodiment of the invention will be de as a direct current motor. The number of poles produced by the ?eld winding when connected to ' scribed in which the motor operates as a six pole alternating current motor and as a four pole di the alternating current source is such that a dif rect current motor. ' ierence of potential exists between the points on 50' Considering ?rst the stator winding for oper the armature winding joined by the equalizers to ation of the motor as a polyphase alternating cause current ?ow through the armature con current motor, the stator winding is illustrated ductors by way of the equalizers. Thus, on alter as a six pole three phase lap winding arranged in nating current excitation the rotor becomes a 36 slots and distributed in two slots per phase per polyphase induction motor squirrel cage rotor. 65 pole. In the developed view shown in Figure 1, asoasss . 3 4 the coils are designated la, 2a, etc., while the slots are designated lb, 2b, etc. Because of space conditions, reference characters are applied to only the first nine of each. The phase windings are differentiated by heavy, light and dot-dash lines. The pairs of coils per phase per pole are connected by short Jumpers designated 21 while other connections for the coils are made by long . ing arranged in two groups and connected in ' parallel, which when excited from a source of three phase alternating current as indicated pro vides a six pole rotating ?eld. ' , For direct current excitation, terminals 4| and 41 are connected to a source. of direct current while the other terminals are not connected to a source. Assuming current flow in the direction of the Jumpers designated 38, it being understood that arrows in Figure 2 and as before clockwise cur the long Jumpers at the ends in Figure 1, specially 10 rent iiow through a coil to provide excitation for designated Ila, 38b and 28c are connected, being a north pole, coils lila and 28a provide excitation broken oil because of the developed view. Seven leads 4|! connect points in the stator winding to terminals designated H, 42, 43, 44, 45, 48 and 41. for a south pole, coils 23a and 24a provide ex citation for a north pole, etc. Or grouping the coils, coils Ia, 2a, la, 4a, la, la, ‘la, la and la The connections of the coils will be more read 15 provide excitation for a north pole, the next nine ily understood from the simplified wiring diagram coils, namely Ila through Ila provide excitation shown in Figure 2. In this ?gure, the coils are for a south pole, the next nine coils provide ex represented by circles. The coils are of identi citation for a north pole, and the remaining nine cal form and therefore it may be assumed that coils provide excitation for a south pole. the circuit through each coil in Figure 2 will 20 The excitation provided by the coils, when con always be from the entering point toward the nected to a direct current source, as described top, regardless of whether the circuit enters the above, is diagrammatically illustrated in Figures coil from the right or from the left. Thus, as 3 and 4. Figures 3 and 4,'being of the same scale suming an instant in which current enters coil as Figure 1, may be aligned therewith to facilitate I from the left, the current how in the coil is 25 an understanding of the direct current excita clockwise, whereas at an instant in which cur tion. The horizontal line 48 is a reference line rent enters coil I from the right. the current flow above which the excitation may be regarded as in the coil is counterclockwise. . positive, 1. e., to provide north pole excitation The coils are arranged in vertical columns in and below which as negative, 1. e., to provide south accordance with their phase, there being six col 30 pole excitation. The numerals I to 28 inclusive umns and six rows inasmuch as there are two indicate reference points corresponding to the coils per phase per pole. For convenience of slots of the stator. In Figure 3, the magnetome switching, the coils of each phase winding are tive force of each coil is represented by a rec divided into two groups arranged for connection tangular block 49. The length of these rectangles in parallel to provide a delta connected stator 35 corresponds to the pitch of the coils while the winding. This arrangement also facilitates ob height of each coil corresponds to the magnitude taining the desired resistance for direct current of the magnetomotive force. Thus the magneto excitation. For example, coils Ia, 2a, 32a, Iia, motive force due to coil is for example extends 25a and 25a constitute one group of phase I, over the face of the stator from slot ID to slot 5b, while coils 8a, ‘la, I3a, I4a, 20a and Isa consti 40 or from points I to 5 and is positive. tute the other group, and these groups are con The resultant magnetomotive force is the alge nected in parallel between terminals 4i and 42, braic sum of the heights of these rectangles over 41, the latter two terminals being connected to the area encompassed by the respective coils. gether for alternating current excitation. Termi This sum is shown in Figure 4>in which the line nals 42 and 43 are connected to one phase of the iii represents the resultant magnetomotive force ‘supply lines, terminal 4| is connected to termi or, since the flux density produced by this mag nals 48 and 41, the three of which are connected netomotive force is directly proportional to the to another phase of the supply lines, and termi _ magnetomotive force, the line 50 is a diagram nals 44 and 45 are connected together and to 50 matic representation of the ?ux density due to the remaining phase of the supply lines, all of the stator winding on direct current excitation which will be seen from the description which ‘ and the- area under this line is the total ?ux follows in connection with Figure 6. Thus the entering the armature. The ?ux density is a phase windings are connected delta. Assume, maximum between slots corresponding to points for example an instant in which current ?ow is 55 4 and Ill, I3 and I9, 22 and 28, and ii and I. maximum into terminals 4|, 48 and 41 and thus Between the slots corresponding to points I I and ?ows out half from terminals 42, 43 and the other I2, 20 and 2|, 29 and Ill, and 2 and I, the ?ux half from terminals 44 and 45. Under such con density is zero, thereby providing neutral zones ditions. current ?ows clockwise in coils Ia, 2a, for the setting of the commutator brushes. Thus 28a, 26a, Ita, No, 230, 24a, Ilia. 38a, Ila, I2a 60 a four pole stationary field is provided when the and counterclockwise in coils 32a, 3Ia, 8a, ‘Ia, 20a. its, Ba, Ba, liia, 29a, Ila and Ho. Assuming clockwise current ?ow to produce excitation for stator winding is connected to a source of direct current. The rotor or armature winding is illustrated a north pole. in phase I coils Ia and 2a provide as a multiple winding of the type used on direct excitation for a north pole. coils ‘Ia and to pro 65 current armatures, wound for a four pole station vide excitation for a south Pole, etc. and in ary field and arranged in 24 slots. In the devel phase III coils Ia and 6a provide excitation for a south pole, coils Ila and I 2a provide excita oped view shown in Figure 5, the coils of the armature winding are designated Ic. 20, etc., tion for a north pole, etc. while the slots are designated Id, 2d, etc. The Therefore, as a re sultant. coils "a, Ila, Ia and 20 provide excita 70 two terminals of each coil are connected to adja tion for a full north pole, coils in, 8a, ‘Ia and Ba cent commutator bars, these bars being desig provide excitation for the next full south pole. nated Ie, 2e. etc. A full pitch winding is illus etc., for a total of six poles. Thus a standard trated, the sides of coil Ic, for example, being three phase delta connected six pole stator wind placed in slots Id and ‘Id. The four brushes in: is provided with the coils of each phase wind 75 are designated 65, 66, 61 and 68, like brushes 9,408,665 '' 5 . being connected together ‘and to terminals II and 10. Corresponding points on the armature wind ing are connected together by equalizing con- . nectors designated ll, 52, etc., 12 equalizing con nectors being illustrated. For convenience, these equalizing connectors are illustrated as con nected to the commutator bars. e Figure 5 is of the same scale as Figures 1, 3 and 4 and may be aligned therewith to facilitate g 6 v former TB. is provided for supplying direct cur rent for generator separately excited neld wind-' ing GP, for the operating coils of the electro magnetic switches and for the brake release coil BR. R ‘designates a resistance in circuit with generator field winding GF. CA is a condenser utilized for timing one of the control switches. GOV designates a governor utilized in the control system. . The control system illustrated is of the type in understanding of the operation. Reference lines l0 which both the starting and stopping of the car ‘II are illustrated above the'armature winding is controlled by an operator in the car. A car and in line witliithef-‘connecting points of the switch is provided in the car, the car switch seg equalizing connectors. These lines are laid off at ment being designated CS and the stationary the bottom in accordance with the spacing in electrical degrees on direct current excitation 15 contacts engaged thereby being designated CUI, CU! and CU! for up car travel and CDI, CD2 and and at the top in accordance with the spacing CD3 for down car travel. UL and DL are con in electrical degreeson alternating current exci tacts of levelling mechanism utilized to bring the tation. Thus it is seen that on direct current car to an exact landing level in case it underruns excitation the equalizing connectors connect points on the armature winding spaceid 360 elec 20 or overruns a floor in stopping. The electromagnetic switches have been des - trical degrees and therefore of the same poten ignated as follows: tial so that there is no current flow in the equal izing connectors other than that which might be due to some irregularity in manufacture. B _ Stator‘ alternating current excitation switches On alternating current ‘excitation, however, 25 C there being six poles instead of four, each line D, Stator direct current excitation switch 'H is 45 electrical degrees apart instead of 30 as DF, Down fast speed switch in direct current excitation. Therefore, on alter Ds,'Down slow speed switch nating current excitation the equalizing connec E, Driving motor switch tors connect points onthe armature winding Il? 30 F, Armature direct current control switch (equivalent 180) electrical degrees apart so that G, Speed responsive switch these points are of equal but opposite potential. UF, Up fast speed switch Thus, on alternating current operation the arma US, Up slow speed switch ture acts in effect as a definite pitch squirrel X, Up fast speed interlock switch cage rotor winding. 85 Y, Down fast speed interlock switch A Reference may now be had to Figure 6 which illustrates a control system for the above de scribed motor utilized as an elevator hoisting motor. For convenience, a simple form of con trol system has been illustrated and various con trol and safety elements are not shown. The circuits are shown in “straight" or "across-the line" form in which the coils and contacts of the ‘electromagnetic switches are separated in such‘ manner as to render the circuits as simple and direct as possible. Therelationship of these coils and contacts may be seen from Figure 68 , . Throughout the description which follows these ' letters will be applied to the coils of the above designated switches. Also, with reference nu merals appended thereto they will be applied to the contacts of these switches, as for example contacts Al. To start the car in the up direction, car switch segment CS is moved into position to bridge con tacts CUI. GUI and CU3. The bridging of con tacts GUI and CUI completes a circuit for the coil of up fast speed interlock switch X. This switch operates to engage contacts XI and to where the switches are arranged in alphabetical separate contacts X2. The separation of con- ’ order and shown in spindle form with the coils and contacts aligned horizontally with the coils 60 tacts X2 prevents the operation of up slow speed switch US and armature direct current control and contacts which they indicate in the wir switch F as a result of the bridging of car switch-1 ing diagram. ' contacts GUI and CU2. The engagement of con The alternating current supply mains are des tacts Xi completes a circuit for the coil of up ignated I, II and III. A triple pole manually operated main line switch designated ML is pro 55 fast speed switch UF. Switch UF, upon opera tion, engages contacts UF'I, UF2, UFI and U1" vided for controlling the'supply of current from and separates contacts UFU. Contacts UFI are the supply mains. The stator winding of the interlock contacts in the circuit for the coil of motor is designated EMS while the armature down fast speed switch DF. Contacts UFI and winding, which is illustrated as a conventional direct current armature, is designated EMA. A 60 UF2 establish direction for the stator winding EMS of the hoisting motor, while contacts UF! direct current generator is illustrated'for sup complete the circuit for brake release coil BR. plying current to the elevator motor armature winding on direct current operation. The gen erator armature is designated GA, its separately excited ?eld winding GF and its‘series field wind ing GSF. This generator is illustrated as driven by a three phase squirrel cage induction motor, the stator winding of which is designated DMS and the rotor of which is ‘designated DMR. Cur At the same time contacts UFl complete the cir cuits for the coils of stator alternating current excitation switches A, B and C. These switches operate to engage contacts Al, A2, BI and Cl completing the circuits for the stator winding of the hoisting motor. The circuit to terminal ll of the motor is from supply main I through con rent for the stator winding on direct current 70 tacts UFI and Al. The circuit to terminals 46 and\l1 is from supply main I through contacts operation is derived from the alternating current UFI and A2. The circuit to terminals 42 and 43 supply mains through a transformer TR and rec is from supply main II through contacts Bi. The tiiler REI connected across a secondary winding circuit to terminals 44 and 45 is from supply main of the transformer. Another recti?er RE! con nected across anothersecondary winding of trans 75 III through contacts UP! and Cl. Thus the phase mosses ., ' 7 windings oi the hoisting motor are connected in delta relationship to the supply mains for a phase rotation of the applied voltage for up car travel sothatasthebrakereleasesthecarstartsin the up direction. This excitation as previously described provides a six pole rotating ?eld to cause operation of the hoisting motor at a fast speed. coils .of switches US and 1''. Switch 1'', upon dropping out, breaks the generator armature mo tor armature loop circuit, while switch US, upon dropping out, breaks the circuit 101' the generator separately excited ?eld winding. Switch US also breaks the circuit for the brake release coil caus ing the brake to be ‘applied to bring the car to a stop at the landing level. Also, switch US As'the car accelerates, the governor switch breaks the circuit for the coil of switch E which GOV closes completing a circuit for the coil of 10 drops out to break‘ the circuit for stator winding speed responsive switch G. Switch G operates DMS of the generator driving motor, shutting to engage contacts GI and to separate contacts down the motor generator set. It also breaks the G2. The engagement of contacts GI completes circuit for the coil oi’ switch D which drops out to a circuit for the coil oi’ driving motor switch E. disconnect the stator winding from recti?er REI. Switch E operates to engage contacts ‘El and E2 15 Should the car overrun the landing, down lev completing a circuit for the driving motor stator elling contacts DL are engaged at the time of the winding EMS. The driving motor starts in op engagement of contacts G2 so that the circuit is eration, driving generator armature GA. completed for the coils or down slow speed switch To stop the car at a landing the car switch DS and switch F. Switch DS, upon operation, segment is centered as the car approaches the 20 engages contacts DSI, D82, D83 and DS‘ and landing, breaking the circuits for the coils of separates interlockoontacts DSI. Switch F, as switches X, UF, A, B and C. Switches UF, A, B above, engages contacts Fl to complete the gen and C, upon dropping out, break the circuits for erator armature motor.v armature loop circuit. the stator winding of the hoisting motor. Contacts DSI and D82 establish a circuit for gen dropping out of switch Ur‘ also breaks, the cir 25 erator ?eld winding GP‘ for current ?ow there cuit for brake release coil BR so that the brake through in the opposite direction so that gen is applied to slow down the car. erator armature GA applies voltage to the hoist As the speed of the car decreases to a certain ing motor armature winding to move the car in value, governor switch GOV opens to break the the down direction. Contacts DSI reestablish circuit for the coil of speed responsive switch G. 30 the circuit for the release coil of the brake with Switch G, upon dropping out. engages contacts the result that as the car is brought to a stop it G2 and separates contacts GI. Contacts G2 com is restarted in the‘ down direction and returned plate the circuit for the coil 01' stator direct cur to the ?oor. As the car reaches the landing, rent excitation switch D through contacts El, G2, down levelling contacts DL separate breaking the X2 and YI. Switch D, upon operation, separates 35 circuit for the coils of switches DS and 1“. These contacts D2 to prevent energization of the coils switches drop out to cause the application oi’ of fast speed switches U1" and DF. It also en power to the hoisting motor armature to be dis gages contacts DI to connect terminals It and continued and the brake to be applied to bring (‘I oi’ the stator winding EMS oi the hoisting the car to a stop at the landing level. Also switch motor to recti?er REI. This causes excitation 40 Etdrops out to shut down the motor generator of the stator of the hoisting motor as a tour pole stationary ?eld as previously explained. Assume that the car has underrun the ?oor so that up levelling contacts UL are engaged at the time contacts G2 engage. Under such conditions, contacts G2 also complete a circuit through con tacts‘UL, coll oi up slow speed switch US, inter lock contacts DSi, coil of armature direct cur rent control switch F and contacts G2, X2 and YI, causing the operation of switches US and . 1". Switch US, upon operation, engages contacts USI, U82, U82 and US‘ and separates interlock contacts USU, while switch F, upon operation, engages contacts PI. The engagement of con tacts Fl connects terminals II and 10 of the hoisting motor armature winding across the gen erator armature GA. The engagement of con tacts USI and U82 completes a circuit through generator separately excited ?eld winding GF in se . The car is started in the down direction by moving car switch segment CS downwardly to bridge contacts CDI, CD2 and CD3. This causes operation of down fast speed interlock switch Y and down fast speed switch DF instead of switches X and UF. Switch DF establishes di rection for the elevator hoisting motor stator winding so that upon completion oi’ the circuit for this winding the phase rotation of the ap plied voltage is for operating the car in the down direction. Otherwise operation of the system is similar to that set forth for starting the car in the up direction and will not be further described. The car may be operated at slow speed by mov ing the car switch segment into position bridg ing only contacts GUI and CU2 or CDI and CD2. In such event switch F and‘ either switch US or switch D8 are operated to cause operation of a direction to cause generator armature GA to 60 the hoisting motor on direct current as above de apply voltage to the hoisting motor winding of a polarity for continued up car travel. At the same time contacts U82 reestablish the circuit for the brake release coil to cause release of the brake. Contacts USI reestablish the circuit for scribed. ' ‘ ' Thus it is seen that a motor is provided which acts as a polyphase alternating current motor for fast speed operation and which may be operated at a slow speed preparatory to stopping or for the coil of switch E, momentarily broken by the the levelling operation. There is no increase in separation of contacts GI, condenser CA main size of the motor over that for a single speed taining switch E operated during this period. polyphase alternating current motor to provide The voltage 01’ ‘generator armature GA is cor such fast speed operation. Owing to the fact that related to the strength 01' the excitation of the 70 there is no ?xed relation between the speed on stator winding and the number oi’ armature con alternating current excitation and that on direct ductors to cause the hoisting motor to operate current excitation, as in the case for example oi.’ as a direct current motor at a slow speed. ' alternating current motors o! di?'erent pole num-I As the car reaches the landing up levelling con bers, the speed on direct current operation may , tacts UL separate. breaking the circuit for the 75 be as low as required to obtain the desired speed 2,408,665 ' \9 _ , of operation or the cai'\As the power required to operate the car at slow peed is only a fraction of that required to operate it at fast-speed, a I small motor generator set may be utilized and the commutator of the motor may be small. While described for only one slow speed on direct current operation, it is to be understood that more than one speed may be provided, as for ex 10 be understood that the invention is applicable to polyphase alternating current excitation of other numbers of phases. Also, while the stator winding has been described as adapted for mesh connection, it may be connected star. The mesh connection, however, admits of a more simple switching mechanism and minimizes the number of leads from the motor. As many changes could be made in the above ample, by controlling resistance in circuit with the generator ?eld winding. The system of con 10 construction and many apparently widely differ ent embodiments of this invention could be made trol illustrated is simply by way of example and, without departing from the scope thereof, it is although a car switch control elevator system intended that all matter contained in the above has been described, the invention is applicable to description or shown in the accompanying draw other forms of elevator systems such as push but ton control systems. ' - > An important feature of the invention is the provision of an armature winding having equaliz 15 ings shall be interpreted as illustrative and not in a limiting sense. ing connectors joining points of equal potential What is claimed is: 1. An electric motor having a ?eld winding the on direct current excitation and which serve on coils of which are so wound and connected that alternating current excitation as connectors for 20 when certain points ‘on the winding are connected to a source of direct current a stationary ?eld of current ?ow in the armature conductors. This is at least two pairs of poles is provided and when satis?ed by a multiple wound armature with certain points thereon are connected to a source equalizing connectors for all coils but it is to be - of polyphase alternating current a rotating ?eld understood that a less number of equalizing con nectors may be employed, as for example by 25 of a different number of pairs of stationary poles is provided, and an armature winding wound for omitting every other one. The actual arrange the number of said pairs of stationary poles and ment of the armature winding depends on the having equalizing conductors connecting points stator winding. The stator winding should pro of equal potential when the ?eld winding is con vide at least four poles on direct current excita tion as otherwise no points of equal potential 30 nected to said source of direct current. 2. An electric motor adapted for operation on are provided on the armature winding to which polyphase alternating current and on direct cur equalizing connections may be made. On alter rent comprising; a ?eld winding having a plu nating current excitation of the stator winding, rality of coils so wound and connected that when a difference in potential is had at the points of connection oi.‘ the equalizing connectors to cause 35 certain points on the winding are connected to a source of direct current a stationary ?eld of at current ?ow in the armature conductors when least two pairs of poles is provided and when the number of poles is less than the number of certain points on the winding are connected to poles on direct current excitation or greater than a source of polyphase alternating current a ro but not a multiple of the number of poles on direct current excitation. However, in a great 40 tating ?eld of a different number of pairs of poles is provided; and an armature provided. with a many of these combinations, the current ?ow in commutator and. wound for the number of poles the armature conductors on alternating current of the stationary ?eld and having equalizers con excitation would be insufficient for satisfactory necting points on the armature ‘winding 360 elec operation. For elevators, it is preferred to have a combination of pole numbers in which on alter 45 trical degrees apart when the ?eld winding is connected for direct current operation; the num nating current excitation the points of connection ber of poles of the ?eld winding when it is con of the equalizing connectors are not less than 120 nected for alternating current operation being so electrical degrees or more than 240 electrical de selected that the points of connection of the grees apart or any equivalent such as not less equalizers to the armature winding are of a num 50 than 480 or more than 600 electrical degrees ber of electrical degrees apart such that current apart. Thus for example, a stator wound to pro ?ows in the armature winding by way of the vide eight poles on alternating current excitation equalizers. ' and six poles on direct current excitation is con 3. An electric motor having a ?eld winding and sidered practical. A combination in which the o a rotatable winding, said ?eld winding being so points of connection of the equalizing connectors wound and having leads from such points there on alternating current excitation are 180 electri cal degrees apart, such as the combination illus trated, or equivalent would be an optimum ar on that when certain of said leads are connected to a source of direct current there is provided a rangement. stationary ?eld of at least two pairs of poles and polyphase alternating current hoisting motor is determined by the requirements of the particu source of polyphase alternating current there is provided a rotating ?eld of a number of pairs of poles which is a fraction of or prime to the num In elevator operation, the number of poles of a 60 when certain of said leads are connected to a lar installation. In the case of geared machines, such factors as gear size and sheave diameter have a direct bearing on the number of poles. Thus in the case of elevators, the number of ber of ,pairs of poles of the stationary ?eld, said rotatable winding being wound for the number of said pairs of stationary poles and to have points of equal electrical potential when the ?eld wind stator poles on alternating current excitation is ing is excited to provide said stationary ?eld, a given factor so that the stator is wound and equalizing conductors connecting said points of provision for connection is made to provide a dif ferent number of poles on direct current excita 70 equal potential, said conductors serving as end connectors for current ?ovv between conductors tion. It is preferred to provide a low number of poles on direct current excitation to minimize I of said rotatable winding when said ?eld winding is excited to provide said rotating ?eld to cause the number of brushes. operation of said motor as a polyphase induction While described as applied to a three phase motor at a certain speed, a commutator for said motor on alternating current excitation, it is to i 2,408,665 ' ='- 11‘ rotatable winding, and brushes for said commu tator adapted for connection to a source oi di rect current when said ?eld winding is excited to provide said stationary ?eld to cause operation of said motor as a direct current motor at a certain speed. 4. An electric motor having a ?eld winding and an- armature winding, said armature winding be ing wound for at least two pairs oi stationary ?eld 12 ing ?eld oi adiiierent number of pairs of poles is provided; and an armature wound for the num ber of poles of the stationary ?eld and provided with a commutator and brushes and adapted when the brushes are connected to a source 01' direct current of a certain voltage with direct current of a certain value supplied to the ?eld winding to cause operation of the motor at a certain speed, said armature having equalizers poles and to have corresponding points under like 10 connecting points on the armature winding-360 poles of equal electrical potential, equalizing con electrical degrees apart when the ?eld winding ductors connecting said points, a commutator for is connected for direct current operation; the said armature winding, brushes for said commu number of poles oi.’ the ?eld winding when it is tator, said stationary ?eld winding being wound connected for alternating current operation be and adapted, when certain points thereon are ll ing so selected that the points of connection of connected to a source of direct current, to provide a stationary ?eld oi’ the number of pairs of poles for which said armature winding is wound to cause with said brushes connected to a source 0! direct current operation of the motor as a direct current motor and, when certain points there on are connected to a source 01' polyphase alter nating current, to provide a rotating ?eld o! a number of pairs oipoles to cause current ?ow be tween conductors of said armature winding through said equalizing conductors as end con nectors sumcient to cause operation of said motor as a polyphase induction motor. , 5. An. electric motor having a ?eld winding and an armature winding, said armature winding be ing multiple wound for at least two pairs 01 sta tionary ?eld poles-and having equalizing con the equalizers to the armature winding are of a number 0! electrical degrees apart such that cur rent ?ows in the armature winding through the equalizers to cause operation of the motor at a speed determined by the number of poles. 8. An electric motor adapted for operation on polyphase alternating current and on direct cur rent comprising; a stator having a polyphase lap winding with its coils so connected that when certain points on the winding are connected to a source of polyphase alternating current a re tating ?eld of a certain number of pairs of poles is provided and when certain points on the wind_ ing are connected to a source or direct current a stationary ?eld or at least two pairs of poles is provided, the number oi’ pairs 01' poles of the rotating field being di?erent from ductors connecting corresponding points thereon the number of pairs of poles of the stationary spaced 360 electrical degrees under such station ?eld; and an armature having a multiple wind ary ?eld excitation, the coils of said ?eld winding 35 ing wound for the number of poles of the sta being so wound and connected that, when cer tionary ?eld, said armature being provided with tain points on the ?eld winding are connected to a commutator and brushes and having equalizers a source of direct current, there is provided a connecting points on the armature winding 360 stationary ?eld oi the number of pairs of poles electrical degrees apart when the ?eld winding for which said armature winding is wound and, 40 is connected for direct current operation; the when certain points thereon are connected to a number of poles oi’ the ?eld winding when it is source of polyphase alternating current, there is connected for alternating current operation be provided a rotating ?eld of a number of pairs ing so selected that the points 01' connection or of poles to cause said points on said armature the equalizers to the armature winding are of a winding to be spaced a number of electrical number of electrical degrees apart such that cur degrees within a range of 120 and 240 electrical rent ?ows in the armature winding through the degrees or equivalent. equalizers as end connectors to cause operation 6. An electric motor having a ?eld winding and of the motor as a polyphase squirrel cage induc an armature winding, said armature winding be tion motor at a fast speed determined by the ing multiple wound for at least two pairs of sta 50 number oi’ pairs of poles, and the armature be tionary ?eld poles and having equalizing con ing adapted when the brushes are connected to a ductors connecting corresponding points there source of direct current of a certain voltage with on spaced 360 electrical degrees under such sta direct current of a certain value supplied to the tionary ?eld excitation, said ?eld winding being field winding to cause operation of the motor wound and adapted, when certain points thereon as a direct current motor at a slow speed. are connected to a source oi’ direct current, to 9. An electric motor adapted for operation on provide a stationary ?eld oi the number of pairs three-phase alternating current and On direct oi’ poles for which said armature winding is current comprising: a stator having a three wound and, when certain points thereon are con phase lap winding distributed in a certain num nected to a source of polyphase alternating cur ber of slots per phase per pole and having jump rent, to provide a rotating ?eld oi.’ a number of ers so connecting its coils that when certain pairs oi.’ poles such that the ratio of the number points on the winding are connected to a source of said pairs of poles of rotating ?eld to the num of three-phase alternating current the phase ber of said pairs oi‘ poles of stationary ?eld is windings are delta connected and provide a ro between V; plus any digit including zero and % 65 tating ?eld or a certain number of pairs 01' poles Plus said digit. ‘ and when certain points on the winding are con 7. An electric motor adapted for operation on nected to a source 01' direct current a stationary polyphase alternating current and on direct cur ?eld of at least two pairs of poles is provided, rent comprising; a ?eld winding having a plu the number 01' pairs of poles of the rotating ?eld rality of coils so wound and connected that when 70 being diil'erent from the number of pairs of poles certain points on the winding are connected to of the stationary ?eld; and an armature having a source of direct current a stationary ?eld of at a multiple winding wound for the number of poles least two pairs of poles is provided and when cer of the stationary ?eld. said armature being pro tain points on the winding are connected to a vided with a commutator and brushes and having source of polyphase alternating current a rotat 75 equalizers connecting points on the armature 2,408,665 13 V14, winding 360 electrical degrees‘ apart when the ?eld winding is connected for direct current op eration; the number of poles of the ?eld wind ing when it is connected for alternating current nectors to cause operation of the motor as a operation being so selected that the points of con nection of the equalizers to the armature winding are of a number of electrical degrees apart such that the armature acts as a de?nite pitch squir rel cage rotor with current ?ow in the armature conductors through the equalizers as end' con- 10 brushes are connected to a source of direct cur three-phase squirrel cage induction motor at a fast speed determined by the number of pairs of poles, and the armature being adapted when the rent of a certain voltage with direct current of a certain value supplied to the field winding to cause operation of the motor as a direct current motor at a slow speed. JACOB DANIEL LEWIS.