US1709134A - best available cops - Google Patents

Description

April 16, 1929- J. D. LEWIS 1,709,134

ELEVATOR Filed Dec. '7, 1921 awuemoc 4 M 551 Que M4424 32 M Patented Apr. 16, 1929.

UNITED STATES PATENT orifice.

JACOB D. LEWIS, or YONKERS, NEW YORK; ASSIGNOR 'ro o'rrs sLEvAToR COMPANY,

OF JERSEY CITY, NEW JERSEY, A CORPORATION on NEW JERSEY.

ELEVATOR.

AppFieation filed December .7, 1921. Serial No. 520,4 75.

My invention relates to controlling apparatus for electric current motors, more particularly as described and shown as .a controlling apparatus for alternating current motors for elevators.

:It has been found impractical heretofore in so when the motor-is run .on a-6O cycles current.

it is impractical to build the drivingor hoisting motor with agreater speed reduction than ,car running at- 600 F; P.,M.=as its high speed be applied to bring the .car'to rest. Atthis ear speed of 200 F. P. M. the moving masses'of .the elevatorswould jstill have considerable; .kinetic energy with the result that the car would slide, making it dilficult to. secure fgoodTlanding S? and wouldalso result in rapid deterioration of-the brake linings. The purpose of the present invention is to overcome these-and other obj ections in alternating current elevator installations byproviding means whereby the car lowspeed is reduced. to say one-ninth --of the high speed, thereby actually reducing the kinetic energy. of the moyingpartsto say; one eighty-first (1/81) partofits energy at high speed, so that no ditficulty is' experienced in makingr good-stops and resulting in a long life of the brake liningsr I a I Another object of the present invention I show with the use of an induction motor as an auxiliary apparatusthat a-current of onethird (1/3) line frequency canbeobtained from its phase. wound .rotor so that the low speed winding of the main or hoisting motor 9 .can. be thrown on this supply and thereby re duce its speed to one-third (l/3) For a further ObjCCtOf the invention I employ the auxiliary induction motor as an 1111- I ,pedance in series with themaiu or hoisting motor for the purpose of lin iiting the current to the hoisting mot-or, both. to its highand low speed windings. This eliminates the stator v resistance, commonly used prior to my invention; the present means will decrease the power consumption to a very considerable extentwhen there is a large number of starts and stops per'car mile.

. Other objects of the invention will appear hereinafter. r

This is primarilydue to the fact that .era'tor set. i I The accompanying drawing, illustrates 3 to 1. With this speed reduction an elevator ploying theus'ualhoisting motor in I an elevator, i together with. alconventional type of hoisting riggi ng and brake apparatus, a main yoltage supply of a standardvalue at I a standardrfre uencyjor, tl1e,, motor, and a alternating current elevator installations to,' i

exceed a car speed of 400 F. P. M., especially imy invention;

I itrolledelevato y ariganged in accordance with would be retardedto 200 F. P. M; car speed, at which point the mechanical brake would The, elevatoras shownin thedrawing comfp ri ses.a two s peed AQCf electric hoisting motor, M, of.theisquirrel cage-type, with two .stator. \gindings; supply ipains a b, c, from 5 whicl1l.an 'alte 'nating current is supplied to e r iigl ils ef he tarlend he 'controlling mechanisms,- reversing switches, -U* and D,

. controlling; the phase relation ofcurrent sup- ,plied to the motor;electromagnetically operated switches,G,..E, H and I, electromag- -netic brake; Bidiagrammatically shown, com lpr ising a plurality of magnet coils, a centrifjesall teee s eedv n r J J d mat callyshown,,comprising a plurality of switch contacts successively made as the speed .ofithe motor increases and one contact opened after the others are closed as hereinafter described, the governor being .driven by the motor- 1H, through the vintermediation of a gearing l thegovernor.=when operating causing the successive operation of several of the elements of;t l 1 e.controll1ng mechanism, as more fully-pointed out hereinafter.

The-different landings or stopping points aredcsignated L and L-, and the car switch by the letter K, and the car leveling switch by the letter N. y

Referring now particularly to the supplementary or auxiliary controlling apparatus. itcomprises an induction motor, (hot the slip ring type, employed as a gencratm'. being drirenby another induction motor MQof the squirrel cage type.- --Th eauxiliary apparatus, m'con unction with the certain other elements heretofore referred to, is employed automatically to supply to the lowgspeed Winding of the hoisting motor. M, in'thestoppingoperation. low voltage at a low frequency, reducing the speed of the saidwinding toaconsiderable extent, aat whichreduced speed-the brake large number 'ofstarfts and stops per car mile.

All of which has been told heretoforefi There are two cams, .2 and 3, positioned in the elevator hatchway at each floor landing.

planes. The cams, 2,:are adapted to'opera'te contacts, 5, and cams, 3, contacts 4, of the car leveling switch, N these contacts controlling electrical connections to reversing switches U and D, respectively, to effect maintaining either reversing switch closed whenj the twisting motor, M, is operating on the low ,"braiie magnet '13 at-the same time, receives current th'r'ough wires 56, j57'a'nd 58. and opvoltage, to effect the automatic leveling operation of the car in a descending or ascend-i ing direct-ion to stop at a landing, depending on the position of the car relativelyto the.

cams, cons "itutinc the car leveling zone.

Operation of the elevator as a whole and through a complete cycle .of operation of starting and stopping will now be given. With the parts as illustratedin the drawing, the car is at rest, level with the second or -top floor landing. Let it be assumed that it is desired to bring the car to the first landin n. by opera-ting the lever, 6, of'the car switch being thrown to an extreme-position, to the. left. as that is what- .an operator or attendant would do in operating the elevator to cause it to descend, obtaining a full operatin n condition of the apparatus as a. result as will he sees] hereinafter. The operation of the car switch closes first a circuit for the wieilin-gy'i. 0'1 the e'lectro-mag'netically 0p- 'ZlltWl low-speed switch. E. as follows: from supply main a. junction point 8. by wire 9, cnnlzr't 10. of the llP-ltVtlSlllg switch, U. by wirc 11. junction point 12-, by wire 13. junction point by wire 15. Contact 16, of the car switch K. segment H on the car switch lcrcr (3. and contact 18 of car switch, as the contacts 16 and l8 were bridged by the operation of the car switch lever 6. by wire 19. junction point 20. by wire 21. junction point 22. by wire .23. winding 7 of electromagnet switch E. by wire '24, junction point 25, by wire 26. junction point- 27. by wire 28. junction point- 29. by wire 30, junction point 31, by wire 32, junction point 83, to supply main b. The winding 7 of the electromagnet switch E is therefore energized and the switch E closed. The closing-of the switch completes by its contacts, 34 and 35, a, circuit for the down-reversing switch winding, 36,, as folnot; starting at this-timeat the contact 16 closed, the contacts 47 and .48 en ar ing conffaets and 50, respectively, and contact 51 contactfizthe'back contacts'53 and "54 opening --through the operation of the The cams, 2, form one sel ies and the 'cams, 3, form another series 1 arranged in"vertical I fjUQ-i when o'pen prevent an operation of "are u '-reversing switch, "likewise the contacts spoken of hereinbe fore, when open, prevent an onmtion' of the down-reversing "switch'Dff The "closing of contact-s47, 18, 49

switch. The back contacts 5 3;arein circuit with the winding ofth-e Hpr'eversing switch anus-o completes the circuit forthelow speed windings of the hoisting motor; M. The

crates to lift the brake.

A switch, 55, ,will be closed {by hand throughwhich a source of supply is obtained from the mains, a. b and c, for opemting the motor M". of the generator set, which motor M'. inturn operates the generator G.

Upon the closing of the contacts 47, 48, 49 and 50, of the down-reversing switch, the stator'windings of the generatorG are excited-as well as the'low speed stator windings of the hoisting motor M. Circuits through 'each'are'as follows: from main a, junction point 8, by'wire 59, contacts and 48, by wire 60,'junction point 61, by wire 62, junction point 63, by wire (it, junction pointfif), by wine through one stator winding of the generator G, by wire 67, contact 68. of switch I, by wire 69, junction point 70, by wire 71,

contacts 72 and 73 of low-speed switch E,

they are now closed, by wire 74, contact- 75 of switch C, by wire 76, through one lowspecd stator winding of hoisting motor M, by wire 77, junction point 78, by wire. 79, through the backfcontacts 8 of switch C, by wire 81. junction point by wire 8:3. junction point 84, by wire 85. through a second low-speed stator winding of hoisting motor M, by wire 8(3, contacts '87, of switch C. by wire 88, contacts 89 and 90 of switch E, as they are. now closed as we said before, by wire 91. junction point 92, by wire 93, contact- 94 of switch I. by wire 95, through a second stator winding of generator G, by wire 96, junction 97, by wire 98. junction pcint'29, by wire 30. junction point 31, by wire 32, junction point 33, to the main 6. The circuit for the remaining stator windings of both generator G and hoisting motor M, is as follows: from nia-inc, junction point 99, by wire 100, through contacts 49*and-47 point 109, bywvire' 110, junction point- 111,

y wire 112, through'contacts 113 and 114 of switch E,'-asthey-are closed at this time, by

wire 115,'--contact-116 of switch-C, by wire 117, through a third low-speed stator winding of hoisting motor M, bywire 118, contact 1190f switch C,'bywire 120, through back contacts =121of. switch G, by wire 122, unct-ion point 82, to the main-b as before traced, in the preceding. case 'of the other stator I winding of'both'generator -and hoisting .n1otor t The-above illustrates that the operation .first of switch E,flsecondly, of either reversing stator windings of the hoisting motor M, as well known to those versed n the motor art,

the impedance being of' a predetermined va.lu'e,' the-torque of the hoisting motor being *low a-t'this time results in a slow operation of the hoisting-motor at this time. The rotor winding ofthe generator'is-open at this time and when' closed' by means of an electromagnetically operated'low-speed accelerating switch, F,-theoperation ofwhich-will result in a change of the impedance in both the. stator and rotor windings of the generator G which reduces the total impedanceto a smallervalue, as is well known; also to a predetermined "alue. The torque of the hoisting motor now being greater than it was, the motor increases its speed, and consequently the speed of the elevator car.

I have llustrated only one step of acceleration of the hoisting motor ht, in my invention. that in which the operation of the low speed accelerating switch, F,-eloses and consequently short circuits the rotor winding oi the generator, G; but it is obvious that more. steps could housed with my system of con trol by the usef'of more electromagnetically opera-ted switches or other deviceseaeh to "cut out aresistance in series with the rotor winding of generator G, after which lastly the rotor winding would be short circuited as in the present case. i The circuit for the winding'of the electromagnetically operated switch, F, is :as-followsz'from junction point 109, by wire 123,t-hrough the closed back-contacts 124 of electromagnet switch H',by wire by wire 131, contact 132 of e 125, through the winding 126 of electromagnet switch F, by wire 127, through the closed governor J, contacts 128, by wire 129, contact 94 of electromagnet switch I, to the main Z), by way of wire 95, stator winding of generator G, by wire 96, junction point 97, by wire 98, junction point 29, by wire 30, junction point 31, by wire 32, and junction point 33. Thus the winding of switch F is subject to the counter. E. M. F. of the hoisting motor. The

operation of electromagnet switch F, the contacts of which short circuit the rotor winding of generator G, results in an increase of speed of the hoisting motor M, as told hereinbefore. The circuit is from the sli ring 130,

lizctromagnet switch H, by wire 133, contacts 134 and 135 of electromagnet switch F, which are closed at this time, by wire 136, contact 137 of electromagnet switch H, by wire 138, slip ring 139; also slip ring 140, by wire 141, contact 142, of electromagnet switch H, by wire 143,'contacts 144 and 145, they being closed at this time, by wire 14G, contact 135 back to the rotor as before. The closing of clcctromagnet switch F makes a circuit by means of its contacts 147 and 148, for the operation of the electromagnetically operated low and high speed accelerating switch I. The circuit or the winding of electromagnet switch I is as follows: from junction point 104, by wire 149, junction point 150, by wire 151, through the winding 152 of electromagnet switch I, by wire 153, junction point 154, by wire 155, through closed back contact 156, of electromagnet switch C, by wire 157, junction point 158, by wire 159, through contacts 148 and 147 of electromagnet switch F, they being closed at this time, by wire 160, unction point 27, to main 1), by wire 28, junction point 29, by wire 30, junction point 31, by wire 32, and junction point 33. The operation of electromagnet switch I in my controlling system, closing its three pairs of contacts as a result. short circuits the stator windingof generator G, the remaining impedance in series with the low speed stator windings of hoisting motor M has therefore been cut out, the torque of the hoisting motor has become still greater and the result is a further increase of speed of the hoisting niotor. which is now operating on its low speed windings alone. The contacts 161 and 162 o t the governor swit eh J were originally open, but have closed during the operation of the h isting motor M up to the. present stage, but. to which no e pecial significance is attached at this time other than that theyhave closed.

- As a further operation in my system of con trol, there is the operation of the electromagnetically operated high and low speed switch C, the circuit for its winding 167, is as followsz-froin contact- 16 of car switch K, the circnitup to thispoin't-from main a,being as before traced, segment 17 on the ear switch -lowand-high speed stator \\-'indings of the 'lloisting' motorfifare-inserie's with each other, together' with the stator windings of the generator G, as .-t-he'contacts of elcctrorhagnet switch C thereforecloses as a result of the last-tracedcircui-t closin through the windng 16-7. The electromagnet switch C in operating firstzopens its normally closed or back cont-acts, aften'which for an instant both, the

switch I, which iira. previous operation shortcircuited the saidwindings of the generator, are again open as the opening of one of the bacl'r contacts of electromagnct switch C has deenergized theelectromagnet switch I The top or normally open-contacts of eleetromag; net'switch C-inclosing short circuitsthe low speed stator windings-of (he hoisting motor M. It thus follows that the high speed stator windings of the-hoisting motor M, have been energized',;and that the stator windings of the generator G have? been put in circuit with thehigh speed stator-windingsof the hoisting motor M, and actasanimpedance to these .windin s (as the stator windin s of the generator did with the low speed stator wind- -.ings of the hoistingmotor M. As a consequence, the speed or 'the hoisting motor M is further increased as aresult of the energizing of the high-speedwindings of the said -motor; the-circuitfor thecurrent to the high speed stator windings'ofi-the hoisting motor at this time is froni original supply main '0, to junction point-lOeh-anch thence by wire 105, through a stator winding of generator G, by wire 106, contact 107 of electromagnet switch I, by wire 108, junctionpoint 109, by wire 1 10, junction point 111, by wire 112, contacts 113 and 11 1 of-rele'ctron'iagnet switch E, by wire 115, contacts 116 and 119 of electromagnet switch C, as they are now closed, by wire 118, through ahigh speed stator winding of the hoisting motor M, the windings being connected together at one of their ends which I have shown, we go through another high speed stator winding, by wire 85, unction point 84, by-wire 169, contacts 170 and 87 of clectromagnet switch C, by wire 88. contacts 89 and 90, of electromagnet switch E, by wire 91, unction point 92, by wire 93, contact 94 of electromagnet switch I, by wire 95, through a stator winding of generator G, by wire 96, j unction point 96, by wire 98, junction point 29, by wire 30, junction point 31, by wire 32, and-junction point 33, to main 6. The circuit for the remaining high speed stator windings of the hoisting motor is originally from supply main a, to junction point 65, and thence by wire 66, through a stator windings of generator G, by wire 67, contact-6'8, of electromagnet switch I, by. wire 69, junction point 70, by wire 71, contacts 72 and 73,-of electromagnet switch E, by wire 74, contacts and 171 ofelectromagnet switch G, by wire 172, junction'point 78, by wire 77, through a high speed stator winding of hoisting motor M, and since all the high speed windings are joined together at one of their ends, the circuitpasses through the wire 85, to the main 7/ as previously traced.

The contacts 173 and 174: of the governor switch J, have closed, due to the increase of speed of the hoisting motor M, after its high speed stator windings were energized, the closing of the said contacts serving further to increase the speed of the hoisting motor M, .by making a circuit for operating again the el ectromagnet switch I, which as shown before when the contact of the said switch are closed short circuit the stator windings of generator G, which acted as an impedance to the current to the low speed stator windings of hoisting motor firstly, and to the current to the high speed stator windings of the said motor secondly. The circuit through the electromagnet switch I at this time is, from unction point150, the feed coming from main c, to this point, by wire 151, through the winding 152, of the switch, by wire 153, junction point 154, by wire 175, contacts 176 and 177, of eleetromagnet switch C, as they are closed at this time, by wire 178, contacts 173 and 174 of governor switch J, by wire 179, contact 147, of electromagnet switch- F, by wire 160,- junction point 27, by wire 28, junction point 29, to main I). The speed of the hoisting motor M, increasing after thecontacts 173 and 174 of governor switch J have closed, the hoisting motor M is now operating on full torque and consequently at its high speed to bring! the illf-Y i r car to the first ianding L. The contacts of governor switch J open as a result. deencrgizing electronmgnet F, the rotor windings of g'aierator G, being opened as a result.

In stopping, the car switch lever 6, is brought to center and when normally done so the operation is as follows: first the electromagnet high and low speed switch C will he deenergized, opening the circuit to the high speed stator \\-'indings and closing the circuit to the low speed stator windings of hoisting motor M. The-eiectromagnet low and high speed accelerating switch I will open as a re have decreased to a predetermined value, resulting in closing the contacts 128 of the governor switch J, the rotor windings of generator G will remain open, there will be then the maximum impedance in windings of the generator G, in circuit with the low speed stator windings of the hoisting motor M, which causes the motor to slow down quickly.

It will be observed that the generator G statorwindings are inserted during the slowdown period, because at that time, the torque of the lowspeed stator windings of the hoisting motor M will be excessive, and therefore an eflicient Inethod'of reducing the voltage in the hoisting-motor M is necessary. The contacts 128 of thegovernor switch J will have closedby this time, after which only thestator windings ofthe generator G are in circuit with-the low. speed windings of the hoisting motor;M. The car switch K may have. been centered by this time, but it will be assumed that the speed of the hoisting motor M, is still great enough to hold closed the contacts 162 of the governor switch J, through which a holding circuit is established to hold. closedthe electromagnet low. speed switch 'E, the circuit being had from junction point 12,by wire 180,through contacts 162, by wire 181, junction point 22, to and through the winding '7 of electromagnet switch. E, to main 6 as before. The contacts 161, of governor switch J, likewise -not'hav.- ing. opened as .yet provide 'a. holding circuit for-the down-reversing switch D, circuit is :asl follows: from junction-point 12, byv wire 180, left hand 'cont-act 162, by wire 182, conta'cts 161, o fgovernorswitch J, by wire 183, junction point 184,-by wire 185, contacts 52 and :'51- of down-reversing switch D, by wire 188, junction point 43, through the winding 36 of reversing switch to main 1) as before. Governor switch J, contacts 162, opening at this-time, the electromagnet switch E, opening as a result, cut-soutof the circuitof the lowspeed stator windings of hoisting motor M, the stator windings of the generator in the circuit to the windings of the hoisting motor M. The circuit to the stator winding of the generator G is now through the closed back contacts 209 and 210 of the clectromagnet low speed switch E. Through the other closed back contacts 189, a circuit for the operation of the clectromagnet decelerating and micro-switch H, the circuit of which is as follows: from the junction point 63, by wire 190, through the winding 191 of electromagnet switch H, by wire 192, through closed back contacts 189, of electromagnet switch E, by wire 193, and junction point 102 to main'c. The'back contacts 124 of electromagnet switch H, in opening deenergize electromagnet low speed accelerating switch F, resulting in the rotor windings of generator G being again opened. The closing of contacts194 and 195 of electromagnet switch H closed one side of the circuit for the downreversing switch D. The Circuit for the reversing switch D now being from junction point 44, by wire 45, contact 34, of electromagnet switch E, by wire 196, through contacts 194 and 195 of electromagnet switch H, by wire 197, junction point 27, by wire 28, and junction point 29, to main b, as before. During the interval between the opening of electromagnet low speed switch E and the closing of electromagnet decelerating switch H, the circuit ,for thereversing switch D was through the resistance 198. The reversing switch thereby being kept closed during the change-over period. The closing of contacts 137 and 199, 142 and 200, 132 and 201 -of electromagnet switch; H, placed in circuit with the low speed stator windings of hoisting motor M, rotor windings of the generator G, which now delivers a current to the said windings of the hoistingmotor M, the circuits are as follows: from slip ring 130, by wire 131, contacts 132 and 2010f electromagnet switch H, by wire 202, contact 73, of electromagnet switch E, by wire 74, contact 75, of electromagnet switch C, by wire 76, tl1rough a low speed stator winding of hoistin motor LI, by wire 77, junction point 78, y wire 79, back contacts 80, ofelectromagnet switch C, by wire 81, junction point.82,'by wire 83, junction point84, by wire 85, through a low speed stator winding of hoisting motor M, by wire 86, contact 87, of 'electromagnet switch C, by wire,;88, contac ts '89, of electromagnet switch E,- -by wire203, through contacts 200 and 142, ofelectromagnet switch H, by wire 141, to slip ring l40..', .-A lso -from slip ring- 139, by wire 138, through-contacts 137 and 199, of electromagnetswitch H, by wire 204, Contact 1140f electromagnet switch E, by wire 115, contact 116, of electromagnet switch C, by wire 117, through a low speed stator winding of hoisting motor M, by wire 118, contact 119 of electromagnet switch C, by wire120, through back contacts 121 of electromagnet switch C, by wire 122, junction point 82, back to the rotor of generator G, as traced before.

The generator G is supplying to the low speed stator windings of hoisting motor M power at a very low frequency, which results in a very slow operation of the hoisting motor and elevator car. For example, it will be assumed that the main supply line is 60 cycles current, and auxiliary motor M, which is a low resistance squirrel cage motor, and generator G are wound for 6 and 4 poles, respectively. The synchronous speed of mo- .tor M is 1200 revolutions per minute. Then the frequency of the rotor current of generator 6 4 1200 G X F)- 20 cycles.

The result of the exchange of energy of the motor M aird-geri'er'atorG, can he easily com put-ed being the power delivered 'to the hoist, in gmotor for operating; Knowing duty or load of'the elevator,-spee d, counterweight andother constants, thelpower delivered'by the genera tor G to the lowspeed statb'r wind ings of l1oisting-inotor'.Mis easilyobtained by'lthose versed in the elevator art.

' Assumethat 'thegovernor switch J, contact 161, open 'upon the arrival-lot the-elevator ear-in the leveling zone; circuit to maintain the down eversing' switch *c'los'ed at this time is from:- 'jun'c'tion point 12,;by wire 13,-junction point 14;, through contacts 5, of the-leveling switch N,--as'ithey-are=now closed, the roller 205,'ef the switch N having engaged cam 2, closing' he contacts 5 as a result, by wire 2-06, junction point 39, to undfthroug'h the down-reversingswitch D, winding 36, as before traced, the'other side of the circuit "from the reversing switch winding being traced through the'contaets 194 and 195 of theelectromagnet switch H ,as they are still closed. The elevator car platform coming opposite to the "landing L, whereupon the roller 305 of the leveling switch N rides oil of the cam 2, opening the switch contacts 5, and efl'ects the opening of the down-reversing switch D, and the electromagnet decelerating switch H. "In'this mannerall the electrical circuits to :the hoist: ing motor M, genei aton G, brake winding, etc., are opened, and the bra ke'shoe is applied to bring the elevator car to rest.

n In the eventof"the caroverrunning the landing, contacts ief switch N will be closed by the roller -205 engaging cam 3 whereby circuits similar tofthose described for the down lowspeed operation'by generator G will be closed to return the car to the floor level.

I have described my invention in connection with. the operation of the down-reversi ng switch I). but it will be understood that the operation is the same in principle when the up switch U is operated.

In order to simplify the illustration and (.lcscription. I have omitted from the drawing the usual safety devices such as the limit switches at the upper ends of the hatchway, the emergency switch in the car, the door contacts, etc, as they are unnecessary to illustrate my invention.

It will be understood that my invention is adapted for use with other types of elevator control than the one herein shown as for example, but'not to exclude others, a push button elevator. I desire not to be limited to any particular number of low speed accelerating switches F; they may be as numerous as desired, the greater the number used the greater the refinement'of operation will be. Furthermore, I have for the sake of illustration shown a three phase system of alternating current, but my invention is not confinedto'any particular number of phases; 'Furthermore,'I wish it to be understood that my invention is not limited to the details of construction or arrangement of parts herein disclosed, and that various modifications might be made Within the spirit and scope of the invention.

I claim:

' 1. In an elevator control system, the com bination of an A. C. hoisting motor of the squirrel 'cage type, with statorwindings, a

source of power of a certain voltage and froquenc'y, means'adapted to connect-said source to the stator windings of the hoisting motor, a motor-generator set adapted to supply the hoisting 'motorf-with'power of a low voltage an'dlow frequency as'compared with the volt age and frequency of said source, and speed responsive means adapted to -connect the generator of themotor-generator set to the hoisting motor at a definite speed of the hoisting motor.

2. In an elevator-control system, the combination of a multispeed A. C.-'hoistingmotor comprising "low speed stator windings, an electro-mechanical brake therefor, a source of power of a certain voltage and frequency, a motor-generator set comprised of a squirrel cage motor and a slip ring motor, the squirrel cage motor being adapted to drive the slip ring motor causing it to produce a low voltage of low frequency as compared with the voltage and frequency of said source, and speed responsive means adapted to eifect'a connection between the motor-generator .set and the low speed stator vwindings of the hoisting motorin the operation of stopping the elevator, whereby the speed of the hoisting motor is reduced, and-at which reduced-speed the electro-mechanical brake can be applied to'cause a good stop of the elevator car to be made at .a desired floor landing.

3. In an elevator control system, the combination of a multi-speed A. C. hoisting motor having low speed stator windings, a source of power of a certain voltage and frequency, a motor-generator set adapted to produce a low voltage at a low frequency as compared with the voltage and frequency of said source, and means for connecting the generator windings in series with the low speed stator windings of the hoisting motor as an impedance in the operation of starting and stopping the elevator, whereby the flow of current from said source to the hoisting motor is limited.

' 4. In an elevator control system, the combinationof a multispeed A. C. hoist-in motor having low andhigh speed stator win ings, a source of power of acertain voltage and frequency, a-motor-generator set adapted to produce-a low voltage at a low frequency as compared with the voltage and frequency of said source, and means for connecting the generator windings in series with the low and high speed stator windings of the hoisting motor stator windingsRaliminatedJ the 1 elevator, whereby the flow 5 of? currentfrornsaid' source to the 'hoisting motor -is limited and seirternal' resistances for the 5. In an elevator-control' system, the combinationof an A: C: hoisting motor having low 'andhighspeed' stator-winding s, a main high} voltage supply; for the-motor,- an A. :C. auxiliar'y generator ofth'e'slip ring'type, anelevator-lowspeed-switch adapted to connect in seriesthe'staton-windings of the' a-iixiliary generator and the; low-'spee'd stator windings of; thehoistm'g -"mo tor,' anelevatorf low 3 speed acceleratingswitchadapted to'short circuit the rotor w-indings of the auxiliarygenerator, an elcva'tor lowwnd high speedaccelera'ting switch adapted' to short fcir euitthe stator windings ofgthe' auxiliary' generator,'-'and an elevator high anddow speed switch adapted, whennone of its-contacts :are' closed, to place the =highispeed stator'wvindings o= the hoisting motorimseriesazwith low: speed stator wind'ng's and the-'.-statorwindings lot the auxiliary generator and, when certain of its contacts are closed, to short circuit the-low speed stator windings :of the hoisting motor. {[n anelevator control system, the-combination otmar. G hoisting .motor .having low and highspeed-stator winclings,-a'main voltage supplyzfog the -motor, an A. C. auxiliary,--generator:ofizthe slip; ringi typefan ;.ele-, vator lo'w "speedl'switch'adapted' to connect. in series zzthe statorrswfndings. rof: theauxiliary generator and the low speed stator windings of :the, lioi sting.;mhtor;:an elevator-110w. speed accelerating-[sw tch adapted-"to short -oirc uit the.-rotorlizviindingsioiithiauxiliary; generator, an ;elevator ilow and hi'gh speed accelerating switch: adapted to shortycircuit the stator windings, of the: auxiliary generator; an elevator.-l1igh.:and.-:low speed. switch adapted, when-noneiof-its contacts are closed, to place the high speed;sta.-tor windings of the hoisting motor-in series withits-low speed stator windings and the stator-windings of the aux iliary generator andgwhen' certain of its contacts are closed, to short circuit the low speed stator windings of the hoisting motor, and an elevator. governor. switch adapted, when closed, to effect-the short circuiting of the stator-windings of the auxiliary generator.

7.:In an elevator control -system, the combination of an A. C. hoisting motor having low and highspe'ed stator windings,a main voltage supply for the motor, an A. C. auxiliary generator-of the slipring type, an elevator low speed switch adapted to connect in series the statonw'indings of the auxiliary generator and the low speed stator windings of the hoisting'motor, an elevator low speed accelerating switch adapted to short circuit the rotorlwindings of=the auxiliary generator, an elevator low and high speed accelerating switch'adapted to "short circuit the stator windings oithe auxiliary generator,

an elevator high and low speed switch adapted, when none of its contacts are closed, to

place the high speed stator windings of thehoisting motor in series with its low speed stator windings and the stator windings of the auxiliary generator and, when certain of its contacts are closed, to short circuit the low speed stator windings of the hoisting motor, and an elevator governor switch 'comprising two sets of conta is, one set adapted, when closed, to effect the short-circuiting of the stator windings of. the auxiliary generator,- and the other set adapted, when open, to effect the opening of the rotor windings of the auxiliary generator. 4

' 8. In an elevator control system, the combination of an A. C. hoisting motor having low and high speed stator windings, a main voltage supply for the motor, an auxiliary generator having stator windings adapted to be connected in series with the stator windings of the hoisting motor, an elevator electro-magnetically operated hi h and low speed switch adapted to open the circuit between the main voltage supply and the high speed stator windings and close the circuit between the main voltage supply and the low speed stator windings in the operation of retarding the elevator, an elevator low :rnahsm and lowspeed switch and to insert the stator windings of the auxiliary generator in series withf'the' low-speed stator-windings of the hoisting motor, an elevator low speed switch adapted, when opened, to cut the stator windings of the generator out of the circuit of the low 'speed-stator.windings of the hoisting motor, and anelevator governor switch having contacts adapted, when opened, to open the elevator low speed switch. Y

In an elevator control system, the combination of an A. C. hoisting motor having low speed stator windings, a main high voltage supply'therefor of standard value and frequency, reversing switches for the elevator, an auxiliary generator, having stator and rotor windings. and adapted to generate a current of low voltage at low frequency as compared with that of the main voltage supply for the hoisting motor, a switch operable to open the circuit between the main voltage supply and the hoisting motor, a switch adapted to close to connect together the rotor windings of the auxiliary generator and the low speed stator windings of the hoisting motor, and means to maintain closed one reversing switch during the period between the opening of said first named switch and the closing of said last named switch.

10. In an elevator control system, the combination of an A. C. hoisting motor having low speed stator windings, a main high voltage supply therefor of standard voltage and frequency, elevator reversing switches, an

auxiliary generator having stator windings and rotor windings adapted to produce :1 current of low voltage at low frequencyas compared with the main voltage supply for the and thelow .-speed -:stator windings of the hoisting motor, and means automatically operable to open the clrculttothe hoist ng motor.

prising low; speed stator windings, an electro-mechanicalibltl'ke, a; main "high voltage supply of a standard value at a standard fre--'- quency, an'A. C. moto r generatpnsetecomprised of a squirrei-cageand-n slip r ng inotor, the squirrel cage motor adapted-to dr ve the slip ring-motor causing it to produce a low voltage of low frequency, an elevator low speed switch-adaptedto eliect aconnection between the induced-windings of-thc slip ring motor and the low speed stator wipd ings of the. hoisting motor; in the pperatron of stopping the elevator, whereby the 5 speed of the hoisting motor is reduced; and atwlncn reduced {speed the electric-mechanical (brake can be appliedto-cause a good-stop of-jthe ele- 12. .-In an elevator control system, ;the -con 1- bination'oiazn A. G. hoisting motor,--.compr i s ing lowjspeed stator windings, an-electromechanical brake,.a main l1igh voltage supply of a standard-valueata standard frequency, an A. C. motorrgenerator set1comprised ofa squirrel cage-and a .slipring motor, the squirrel cage motor adapted to drive the slip ring motor causing it to ,produce a low voltage of low frequency, means adapted to disconnect the hoisting motor from the high voltagesupply, and means to connect the induced windings of the slip ring motor and the low speed stator windings of the hoisting motor in the operation o-fstopping the elevator, whereby the speed ofthe hoisting motor is reduced, and at which reduced 'speed the electro-mechanica'l brake can be applied to cause a good stop of the elevator car to be made at a desired floor landing. e

13. In an elevator'control system, the combination of an A. C. hoisting motor, comprising low speed stator windings, an elect-some chanical orake, a main high voltage supplyo'f a standard value ,1! standard frequency, a. motor-generator set comprised of a squirrel cage and a slip ring motor, the squirrel cage motor adapted to drive. the slip ring motor causing it to produce a low voltage oflovv.

slip ring-motor and-the low speed stator wind-- ings ofthe hoistingmotor; in the-operationof stopping the-,elevator, whereby the speed of the hoisting moto-ixisrediiccd, and at which reduced speed the electro-mechanical brake cambe applied'to ceu'seagood stop of theelee vator cart-o be made at a desired floor landing.

-14. lil-anielovator controhsystem, the combination of an .A. .G. hoisting motor, a. main voltage supply there-forofv'a standard-value at r i ast'andard frequency,; an A.C.aufxiliary gen- 11. In an elevator eontrolsystem, the com-' binationoi-an A. C. .holstmg motor, com-' orator, meansadapted to connect in 'series the stator. .ivindingssof the hoisting' motor j andauxiliary generator, the generator having open rotor windings,- and means adapted to short circuit the stator windings and rotor Windingsof themmx i'liary generator. ,ifiijln-anielevator control system, the coln- "aina'tion of an 1L0. hoisting motor,- having lowspeed stator windings,a main voltage supply there-for of standard value at a standard frequency, an A. C: auxiliary generator, means adapted toconnect iii-series the low speed stator-windings of the hoisting-motor and the auxiliary generator, nthe; generator having open rotor zgvinding.s,and meansadapted-to short :circuit. the rotor ivindings of the auxiliary generatoryinsthe operation of starting tl13aleV3tOl. .=i 16. Inan. elevator: control system, the com bination of an A..=C. hoisting fmotoiihaving low speed stato it windings, a mainvoltagesup plytherefor dfa standard value at'a standard frequency, and a [system of control for the hoisting. motor, comprising an A. C. auxiliary generator, an elevator -lo\vspeed switch adapted to connect in series the' stator Windings of (he auxiliary generator and the low speed stator windings of the hoisting motor, and an elevator low speed accelerating switchadapted to short circuit the rotor wind ings of the. auxiliary generator, in the operationof starting the elevator.

'17. In an elevator control system, the combination, of an A. 'C. hoi'sting motor having low speed-stator windings, a main voltage supply therefor of a standard value at a standard frequency, and a system of control for the hoisting motor, comprisingan A. C. auxiliary generator, an elevator low speed switch adapted to conncctin series the stator windings of the auxiliary generator and the low speed stator windings of the hoisting motor, an elevator low speed accelerating switch adapted to short-circuit the rotor windings of the auxiliary generator and means adapted to short circuitthe stator-windings of the auxiliary generator.

18. In-an -elevator control system, the combination of an A. C. hoisting motor having low speed stator windings, a main voltage supply therefor of a standard value at a standard frequency, and a system of control for the hoisting motor, comprising an A. C. auxiliary generator, an elevator loW speed switch adapted to connect in series the stator windings of the auxiliary generator and the low speed stator windings of the hoisting motor, an elevator low speed accelerating switch adapted to short circuit the rotor windings of the auxiliary generator, and an elevator low and high speed accelerating switch adapted to short circuit the stator windings of the auxiliary generator.

19. In an elevator control system, the combination of an A. C. hoisting motor, a main voltage supply therefor, and a system of control for the hoisting motor, comprising an A. C. auxiliary generator, means adapted to connect in series stator windings of the hoisting motor and auxiliary generator, the generator having open rotor windings, means adapted to short circuit the rotor windings of the auxiliary generator, and means adapted to short circuit the stator windings of the auxiliary generator.

20. In an elevator control system, the combination of an A. C. hoisting motor having low and high speed stator windings, a main voltage supply for the hoisting motor, and a system of control for the hoisting motor, comprising an A. C. auxiliary generator, means adapted to connect in series the stator windings of the auxiliary generator and the low and high speed stator windings of the hoisting motor, the generator having open rotor windings, and means adapted to short circuit the rotor windings of the auxiliary generator.

21. In an electric elevator control system, the combination of a multi-speed motor for raising and lowering the elevator car, a main power supply of a given frequency for said motor, means for effecting the various speeds o t said motor by suitably connecting its windings to said main power supply, an auxiliary power supply of a different frequency for said motor, and means for leveling the car with a desired floor, said means comprising automatic means for effecting still another speed of said motor by suitably connecting its windings to said auxiliary power supply.

In testimony whereof, I have signed my name to this specification.

JACOB D. LEWIS.

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