' 

REF ID:A67827 

Patented June 25, 1935 2,005,890 

UNITED STATES PATENT OFFICE 

2,005,890 

MOTOR CONTROL SYSTEM 

James Dunlop, Pa.rk Ridge, Ill., assignor to Westinghouse Electl'1c & Manufacturing Company, a. col']lora.tion of Pennsylvama. 

Application November 13, 1929, Serial No. 406,842 

15 Claims (Cl. 172-152) 

My invention relate& to systems of motor control, and more part1tularly to systems of "motor 

control in which it is required that the speed 

of operation of the motor be mdependent, or 

5 nearly so, of the load bemg dnven thereby 

In the prior art, much thought ha& been directed to the development of motor control systems whereby the speed of operation of a dnvmg 

motor may be mamtamed at a constant value 

10 independent of the load thereon 

In the mam, however, the effort has been to 

control the excitation of the motor under va1ymg load cond1t1ons through means which are 

directly responsive to such vanat1on m load 

15 The most notable example of this type of development is, of course, the compound wound motor, m which an add1t1onal, or ser1e&, field wmdmg disposed m se1ies relation to the armature 

c1rcwt and which, therefore, car11es the total 

20 load current, is employed to vary the exc1ta.t1on 

of the motor m accordance with the load Numerous reflnements have been added to thls type 

of motor, and within certain limits, the regulation produced thereby has been highly satisl5 factory ' 

I propose, however, to vary the excitation of 

a motor m accordance with the "error in speed" 

which results from the variation of load or other 

cond1t10ns Normally, it is true, a given varia30 tion m load will reqwre a given variation m excitation if the speed is to be mamtamed constant Under certain othe:- conditions however, 

this variation m excitation may be either too 

great or not great enough, and a var1at1on m 

35 speed results I propo&e, as stated above, to take 

advantage of thls change m speed to further 

vary the exc1tat1011 suppbed the motor to thereby 

return the motor speed to its correct value 

In certain motor control appbcations, it may 

40 be desirable to obtain the entne vaiiat1on in 

motor excitation through my invention, to be 

heremafter described, while m others it may be 

more desirable to compound the motor m accordancP with the prmc1ples of the prior aJ. t, and 

4.J to employ my deVIce to correct the mmor vanations in speed not compensated for by the usual 

compoundmg means 

A notable example of the latter clac:;s is that 

of the motors employed to drive elevators of the 

.30 gearless traction type, m which precise motor 

regulation must be atta.J.ned while runnmg at, 

and deceleratmg from, high speeds under wide 

variations of loadmg 

In elevators of this type, 1t 1s customary to em55 ploy some form of automatic slow down and 

stoppmg means, whlch may be rendered effective 

either by the movement of the usual car switch, 

or which may be rendered effective by the operation of passenger operated call buttons in the car 

and at the floors served by the elevator It is r 8 

usual to employ one or more steps of deceleration 

prior to the shutting off of the power to the eleva tor motor and the settmg of the brake 

It is of the greatest unportance that, at the 

time the brake is set to brmg the car to rest, the :Ri 

car be movmg at a predetermined rate of speed, 

in order that the force of the brake may be suffl.c1ent to bring the car to rest accurately level 

with the particular floor landing 

The problem of motor control therefore as- fs~ 

sumes its greatest importance during the deceleration period, and the penod Just prior to the 

m1tiation of deceleration The acceleration of 

the motor is less impartant, since it is only necessary that the rate of acceleration be not incon- 20 

sistent with the comfort of the passengers 

The obJect of my mvention, therefore, generally stated, is to provide a motor control system m whlch the speed of operation of the motor 

is independent of the load 25 

More particularly stated, the obJect of my mvent1on is to provide a motor control system in 

which any vs.nation from a predetermmed speed, of the speed of operation of the motor, may be 

utilized to vary the excitation supplied the· motor 30 

to thereby cause the motor speed to return to 

said predeterrmned value 

Spec1fl.cally stated, the obJect of my invention 

is to provide a. control system for motors, in 

which any departure from a predetern11ned rate 35 

of vs.nation m the speed of the motor may be 

utilized to vary the excitation of the motor to 

thereby cause said rate of variation to assume 

said predetermined value. 

My invention will be described with reference 40 

to the accompanying drawings in which, 

Figure 1 is a diagram of an elevator control 

system embodying my invention, and, 

Fig 2 is a g,apruc representation of the change 

m speed of an elevator car, durmg deceleration, 45 

with respect to the distance traveled and with 

i espect to the elapsed time 

Referrmg now to Fig 1, I have provided a drivmg means for the elevator car of the variable 

voltage, or Ward-Leonard type, wherein a driving 50 

motor M, havmg an armature M', and a field 

wmdmg MF connected m parallel relation thereto, receives power directly from the hne conductors LI and L2 The motor M drives a generator 

G, having an armature G', and being provided 55 

@'pp roved for Release by NSA on 09-05-2013 pursuantto E .0. 1352a 
REF ID:A67827 e 

2 9,00IS,890 

wlth a separately excited field wlndmg GF and a 

cumulatively wound series field winding GSF 

A hoisting motor EM has its armature EM' connected In a local circuit including the armature 

15 of the generator G and the generator series field 

winding GSF The field winding E:MF of the 

motor EM ls connected directly across the line 

conductors LI and L2, as shown The elevator 

motor EM drives the elevator car C, at a rate 

10 determined by the value of voltage supplied its 

armature EM' by the generator G, through the 

hoisting drum D over which passes, in the usual 

manner, the cable Ca., one end of which is connected to the car C and the other end of which 

lo is connected to a suitable counter-weight Cw 

The speed and direction of rotation of the elevator motor EM JS suitably controlled from the 

car C by means of the car switch Cs, which m turn 

controls the direction switches I and 2, and the 

20 acceleratmg relays 3 and 4, to thereby change 

the polarity and value of voltage supplied to the 

separately excited generator field wmding GF 

As will be obvious to those familiar with the art, 

the effect of the series field winding GSF is at 

U all times a function of the load carried on the 

elevator car c, and its effect is sumciPnt, or nearly so, under normal conditions, to mamtain the 

voltage of the genera.tor G at such a value that 

the speed of the elevator motor EM is maintained 

30 at a predetermined value depending upon the 

excitation supplied the generator through the 

field winding GF. 

As hereinbefore stated, precise motor control 

ls of particular importance in connection with 

11 elevator systems of the type wherein the deceleration and stoppage of the elevator car at a selected 

floor is automatically accomplished through 

means which are under the control of either 

the operator of the car or of the passengers at 

40 the various floor levels I have, therefore, illustrated my invention as embodied in a system in 

which the automatic slow-down and stopping 

means comprise inductor relays, for an illustration of which type of system reference may be had 

45 to the copending apphcation of Edgar M Bouton, 

Serial No 731,921, fl.led August 24, 1924 As 

described therein, each of the inductor relays comprises a movable armature upon which is disposed 

a coil arranged for energization by operation of 

50 the car switch located on the car Stationarily 

mounted in the hatchway adJacent the several 

floor levels are mductor plates which cooperate 

with. and cause movement of, the aimature of the 

associated relay when the latter is brought ad55 jacent thereto Movement of the armature controls suitable contact members disposed in circuits. the interruption of which causes the deceleration and stopping of the car For purposes 

of description, I have illustrated a system wherein 

60 two steps of acceleration and deceleration are 

provided for Accordingly, inductor relays 2LU 

and ILU a.re effective to cause deceleration of the 

car when movmg in the up-direction, and relays 

65 ILD and 2LD are effective to cause deceleration of 

the car when moving m the down-direction The 

stopping inductor relay SR is effective to cause 

final stoppage of the elevator when moving in 

either direction As will be hereinafter described, 

70 the coils of these mductor relays are suitably arranged for energization by proper movement of 

the car switch Cs To cooperate with the inductor 

relays, I have provided the mductor plates ILU', 

2LU', ILD', 2LD' and SR', one series of which ls 

75 disposed in the hatchway adjacent each floor level 

A primed character has been added to lndlcate 

the association of relays and plates 

As was stated in the description of the variable 

voltage control apparatus, the generator field 

wmdings GF and GSF are so proportioned that o 

under normal conditions the speed of the motor 

may be made nearly independent of the load upon 

the elevator car, or of other varying conditions, 

and will depend only upon the degree of excitation 

supplied through the separately excited field 10 

wmdlng GF To compensate for the variations 

m speed, for which the normal compounding 

means are inadequate, I have proVIded a twoelement regulating device to modify the excitation supplied the generator, through the field 15 

wmdmg GF, by insertmg varying portions of an 

aux1llary resJStor into the circuit of this winding 

The regulating device comprises, first, an element 9 which moves, or is caused to operate, in 20 

accordance with the actual speed of movement of 

the elevator car, and second, an element 1 which 

is caused to move m accordance with a predetermined rate of movement of the elevator car. 

These two elements, as stated, cooperate to vary ~5 

the portion of resistor 8 m the circuit of the separately excited generator field winding GF As 

long as the speed of the elevator car corresponds to its predetermined speed, the value of res1c;tor 8 m the circuit descnbed is constant, since ~o 

the two regulating elements maintain the same 

relative positions However, lf the speed of the 

car assumes a value other than the predetermined 

speed, a relative motion is imparted to the two 

iegulatmg elements to thereby vary the value of :1:; 

i esistor 8 m the generator field circwt by an 

amount sufllcient to cause the actual speed of 

the car to return to the predetermmed value 

A very converuent form of device responsive 

to the actual speed of a moving obJect, and one '10 

which I now consider to be a preferred form, comprises an oidinary fly-ball speed governor 9, having a. rotatmg shaft I 0 to which are pivotally 

fixed the arms 11 carl'y!ng the fly-balls 12 The 

inward or outward movement of the fly-balls 12 ls 4 > 

transmitted to the member 13 as vertica.1 movement The governor 9 may be driven, for example, through swtable reduction gearing 14, by 

the drum 15, around which passes a governor cable 

GCa As shown, the governor cable GCa passes 'r;o 

over a suspension sheave GD and under a tension 

r.heave GT, the ends being attached to the car at' 

the points 16 and 11 The hmlts of movement 

of the member 13 may, of course, be determined " 

directly from the design proportions of the fly- 5; 

balls 12 and the arms 11, for any given speed 

11m1ts of the elevator car C ReSJllently mounted 

on the element 13 for movement therewith JS a 

conducting brush membei 18, which may be connected to one side of the power source, as L2 60 

The remairung element of the regulatmg device 

shown collectively at 1 includes a member 20, 

which carries the auxillary resistor 8 and which 

1s arranged to proVIde the same limits of movement for resistor 8 as are provided for the brush fij 

member 18, the position of the reblst-0r 8 with 

respect to 1ts limits of movement being varied in 

accordance with a predetermmed schedule As 

shown, the member 20 is earned at one end of an 

arm 21, pivoted at 22, and carrying at its othei iO 

end a roller 23 The roller 23 rides upon a cam 

surface 24 formed on the drum 25, which is in 

turn driven at a constant speed, under certain 

heremafter descnbed conditions, by the cam motor CM The motor CM is illustrated as having T.; 

J 
• 

REF ID:A67827e 

' J~ annature CM' azμl 1ts field wmcbng CMF con- necte.d m pa.rallel rela.t1on 

A plurality of contact members 26 a.re airanged 

at different p,oints along the resistor 8, and are :; ci1spo.sed fo-r engagement by the brnsb member 18, 

depending up.on the relative pos1t1on of the brush 

and the res1stoi One terminal of the res!Sto1 

8 is connected to the separately excited field 

wind.mg GF, ma manner to be hereinafter deM scribed It will be apparent, therefore, that the 

amount of resistor 8 inserted m the generat01 1lel.d circwt will depend upon the relative pos1t1ons 

of the brush member 18 and the resistor 8, which are in tu1n controlled by the speed of the car and 

l:> the configuration of the cam surface 24, respectively 

The configuration of the cam surfaC'e 24 may 

bie tiest·understood with reference to Flg 2 of the 

dra.wmgs in which I have illustrated, in c..urve 32, 

lf) t)le variat10n m speed of an elevator Ytith respect 

to the cbstance traveled after 1mtiat10n of deceleration As shewn, the deceleration of the car is mit1ated at the point at wluch the curve 32 

intercepts the ordinate, expressed in feet per 

3.'i mmute, at whi<:h time the &peed of the car is 

approximately 600 feet per mmute As also 

sllown, the ca.r is brought to rest at t.he pomt at 

wJ:uch the curve 32 intercepts the abscissa, ex- prtissed m feet, which occurs when the car reaches 

:io a point approximately 12 feet in advance of the 

point .at which decele1 ation is initiated 

From the standpamt of efficiency of the elevator system, it is desuable that the curve b<" 

as "steep" as possible, of course From the 

3.1 standpoint of the comfort of the passengers, however, it is desuable 1,hat the curve be both gredual Eμid regular The configm-ation of the cu1 ve 32 

111, therefore, determined m acco.·dance with thPse 

two factors I have noted on the CUI"le the pemts 

'\O U and 28, as being the points at wh1cl1 the automatic stopping means are su<'cess1vely effective 

to cause further deceleration o! the ca1 and 

tqe point 29 as indicating the rate of movement 

of the car at the time the motm circuits are final4i\ ly mteri"Upted and the usual brake caused to 

bril\g the car to rest It wlll be appai·ent that it 

is highly important, when the car 1eachei: Lbe 

pemt 29, that its rate of movement b.,, precisely 

the same for each c;low-down operation 

:>O AB stated, I prefer to drive the drum 25 at a constant 10.te In des1gl\ln~ the cam surface 

therefo1e, 1t is fi1st necessary to t1ansform the 

speed-distance CUl ve illustrated ac; curve a2, to a speed-trme <'Une illustrated as cu1ve 3!1 This J~ latter curve 1Uustrates, as wlll be obv1ouc; to one f~~mllar with the art, the E<peed at which the rEJr 

should be moving at any definite time afte,. deceleration is 1mtiated, the ordinate being ex- pressed in feet per mmute as before, and the 

bQ 11-b.sclSSa being expressed in minutes 

~nowmg the characteristics of the &peed dPvice 9, it is possible to calculate the distance the 

brush member I 8 thereof will move if the car decelerates from full speed to c;ome predeterm.ned 

0.0. lower speed From the curve 30 it is possible to 

determine the time that should elapse whllP the 

Cal' is decelerating to this extent Theref01e, 

thec;e data, taken in conJunction with the known 

rate of movement of the drum 25, dPtermme the 

iO configuration of the cam surface 24, since it is 

known that over a definite period of time, the cam surface should be such as to ea.use the aim 

t( io change the po&tion of the 1-es1stor 8 by an anioupt equal to the changf' in posit10n of the 

71i q:rusl\ ~epiber l8 on the speed- device 9 Stated 

3 m another way, the curve 24, expressed in c1reula.r coordinates, is the eqwvalent of curve 30, exp1essed in rectangular ccordmates 

By determining a number of such points, the 

complete configuration of the cam surface 24 is · 6 

determinable In the illustrated embodiment I 

have reduced the speed of the drum 25, through 

suitable reduction gearing 31, to such an extent 

that the d1um makes one complete ie'ltolut1on 

wlule the car is decelerating f1om full speed to M zero &peed 

As \\lll be obvious, when the car is stat1o:iary, 

the brush member f3 occupies its lowest position, when the car is started and accelerated 

to any p1edetermmed speed, the brush mem.ber lfi 

18 rL">es a conesponding amount. and when the 

ca1 is decelerated to zero speed, the bru~h mem- be1 ID retums to its origmal position agrun The 

reSJstor 8 must, therefore, r.iove th1ough a co1-

1 ef.pondmg cycle, and m subs! a11t1al synchro- ~ 

msm v.ltll b1ush member 18 If tile car moves through tlm cycle at the p1escnbed rate. this 

movement \Ull be i.1 ex.i.ct 'iynchro:n:;:m, of course As ;ull be made mo1e appnreut m the course or the df'&cr•phon, the ca!ll motor CM is em- l:Ji 

ployed only for the purpose of revohmg the 

drum 25 m a direction to cause the resistor 8 

lo mo\e from a position correo;.poncbng to a i unnmg speed of the car, to 1,he illustrated posit.on At the exp1rat1on of the olow down pe- 3Q 

11od, the1efore. the motor CM may be disconnected f1 om lhe lme to thereby conserve power 

'ro accomplish this, I mterpo~c a voltage relay 

ln e~C'h o! two circuits by way of which the 

moto1 CM may be cpPrated The1e ielays a.re :Sii 

so propo1•10ned that they arc not act1.1.atcd untJl 

the &peed of the elevato1 reaches a p1edetermrncd \.alue, but., l.avmg been actuated, are inamtumed m that cond1t10n until after the ex- p112 hen of the slov. down period Then oper- '4<> 

at1on m•v beo;t be understood m the description 

of an a&sumed elevato1 ope!at1on, hereinafter 

given 

I employ the sprmg 89 to co.use I.he d1 um Z5 

to revolve from its illustrated pontlon to a ¥-

pm .. tion co1-rC'::;pondmg to a n:.nnmg speed of 

the ca1 The strength of the :;pung rn so proPO! t1oned as to cam,e the i es.star 8 to r!i.e in 

1-..ub11tant1al synchrom&m w:th t.l1e brush mi>mber 

13 when the latter rises 1n iesponse to the ac- 50-

celeratlon of the car c 

In ord<'r t.l:lat the resistor 8 may be mamta1ned 

111 .ts 1Ilust1ated po .. 1t1on ,.,h1le the <..ar is sta.-

t1onaiy I ha'lte providl"d the la~chirig device 89, cl~\sposed to engage the latch portion 88 of the 5:i 

drum. 25 Ythen the IattC'r 1.:; in its il1ust• ated pos1-

hon Th.is device there:fo1e 1e>t.1ams the spring 

89 unler:.s the c01l 68 thereof h actuated to re- ti act the core me:nber, which action take~ place 

only upon mo\.ement o! the control devices to 110 

start the car 

As will be developed m t!:>.e lat.ei d1scu"!s1on, it 

is at I 1mes desirable that the car shall be ac- ccle1 at.Pd to only 1t'! mtermed1ate speed Under these> co11d1t•ono; thf> brui.h member 13 will 60 ri~e through only a portion of its complete pa.th 

and huncc t.he movement; of 1.he resistor 8 should 

be s11mla1ly 11m1ted To accomplish this I em- plcy the a.ddit1onal latclnng de•nce I zn disposed ~, u to engage' thr latch port.ion 88 of the drum 25 

when tl"Je latter hac; rotr.ted under the mfiueece 

of spung 89, to such S..'1 extent as to cause the 

resistor 8 to use to its predetermined limited 

position 

The operation o! IOY system niay best be un- 75 
REF ID:A67827e 

4 2,005,890 

derstood with reference to an assumed operation 

Assuming that it. is deblred to move the car 

upwardly at high speed, the operator may move 

5 the ca.r switch Cs to its extreme position m a 

counter-clockwise direction to complete c1rcwts 

for the up-direction switch I and acceleratmg relays 3 and 4 The circuit for up-direction switch 

I extends from lme conductor LI through con10 ductor 60, the contact members 61, 62 and 63 of 

the car switch Cs, conducto1s 64, the coil 65 of 

up-direction switch I, conduct.ors 66 and 61, the 

coil 68 of latching member 69, and conductors 

10 and 11 t<l line conductor L2 The cnergiza- 16 tion of the coll 65 actuates the armature of upd1rection switch I to thereby close the contact 

members a, b, c and d 

The closing of contact members a completes 

a self-holding cucmt for up-duection switch I 

20 which extends f1om lme conductor LI thr<lugh 

conductor 12, the contact members 13 of stopping inductor relay SR, conductors 14 and 15, 

contact members a of up-di1ection switch I, 

conductor 16 to the c01l 65 and thence to line 

26 conductor L2 as prev1ously described Thereafter, the c1rcmt of up-direction switch I is 

independent of the position of the car F.witch Cs, 

being under the control of the contact members 73 of the stopping mductoi relay SR 

30 The closing of contact members band c completes a circuit to the separately excited generator field wmdmg GF which circwt extends from 

line conductor LI , through conductor 11, contact 

members b of up-direction switch I, conductors 18 

85 and 19, the c:;eparately excited field wmdmg GF, 

conductors 80 and 81, contact members c of updirection switch I, conductors 82 and 83, resistor 

84, conductor 85, the flexible conductor 86, a portion <lf the resistor 8 the contact brush 18, the 

40 flexible conductor 81 and conductor 11 to line 

conductor L2 

The generator now being supphed with excitation of a defl.mte value, through the separately 

excited field winding GF. the geneu.ted voltage 

45 builds up to a. value deteunmed by such excitation, and causei; the motor EM to rotate at •ts 

slow speed 

Movement of the c.ar switch Cs to its first position also completes a circuit it will be noted, to 

50 the coil 68 of latching member 69 This member 

is, therefore. i·etracted from its position of engagement with the latch portion 88 on drum 25 

and permits this device to start moving in a 

counter-clockwise direction under the mfluence 11f 

55 the spnng 89 

The c1rcmt for mtermed1ate speed accelerating 

relay 3 extends f1om line conductor LI through 

conductor 60, contact members 61 62 and 90 of 

car switch Cs, conductors 91 and 92, the coil 93 of 

60 relay 3 and conductors 94, 95 and 96 to lme conductor L2 Relay 3 is therefore, actuated to close 

its contact members a and b and to open its contact members c and d 

The closing of contact members a completes 

65 a self-holding c1rcwt for relay 3 which extends 

from line conductor LI through conductors 12 

and 91, the contact members 98 of intermediate 

speed down-d1rect1on inductor relay ILD, conductor 99, the contact members IDD of interme70 d1a.te speed up-direction inductor 1elay ILU, conductor I 0 I, the contact members a of relay 3, conductor 102, the c01l 93 of relay 3 and thence to 

hne conductor L2, as previously described.. 

'!he closing of contact members b on relay 3 

75 is effective to exclude a portion of resistor 84 from 

the circwt of the separately exCJted generator 

field wmding GF, which circuit now extends, as 

previously described, to the pomt I 03 on conductor 83 and thence through conductor I 04, the 

contact members b of relay 3, conductor 105, a 5 

portion of the resistor 84 and thence to lme conductor L2, as previously descnbed The additional exc1tat1on increases the generator voltage 

and thereby causes the elevator motor EM to 

accelerate to its intermediate speed 10 

The circuit for high speed accelerating relay 

4 extends from lme conductor LI through conductor 60, the contact members 61, 12 and IOI, 

conductors I 01 and I 08, the coil I 09 of relay 4 and 

conductors 94, 95 and 96 to line conductor L2 15 

Relay 4 is, therefore, actuated to close its contact members a and b and to open its contact 

members c and tZ The closing of contact members a completes a self-holding c1rcu1t for relay 

4, which circuit extends from lme conductor LI 20 

through conductors 12 and 110, the contact members I 11 of down-direction high speed inductor 

relay 2LD, conductor 112, the contact members 

113 of high speed up-direction inductor relay 2LU, 

conductor 114 the contact members a of relay 4, 25 

conductor 115, the coll 109 of relay 4 and thence 

to llne conductor L2, as previously described The 

closing of contact members b of relay 4 ls effective to exclude the remainder of resistor 84 from 

the c1rcmt of the separately excited field winding 30 

GF, which c1rcu1t now extends from lme conductor LI, as previously described, to the Junction pomt I 03 in conductor 83 and thence through 

conductor 111, the contact members b of relay 4, 

conductor 118, conductor 85, and thence to line 35 

conductor LZ, as previously described 

By reason of the additional excitation now 

provided thr<lugh the field winding GF, the generator G increases its voltage and thereby causes 

the elevator motor EM to accelerate to its full 40 

running speed 

Movement of the car switch Cs to its extreme 

pos1t10n also completes a c1rcu1t to the coil 119 

of latching device 120, which circuit extends 

from line conductor LI through conductor 60, 45 

the contact members 61, 62 and I 06 of car switch 

Cs, conductors I 01, I 08 and 121, the coil 119 

of latching device 120, conductor 122, and thence 

to line conductor L2 by way <lf conductor 11 

Now being energized, the coil 119 retracts the 50 

latching device 120 from a position of engagement with the latch portion 88 of drum 2&, 

thereby permitting thls latter element to continue to rotate until such a tune as the roller 23 

engages the cam surface 24 at the point 123, at 55 

which time the drum may be stopped in any converuent manner, as by a stop member 5& 

As the car IS accelerated from zero speed to 

its full running speed, the element 13 of the device 9 is caused to move upwardly at a rate de- 60 

termmed by the rate of acceleration of the car 

C In order that the brush I 8 may remam in 

engagement with the same contact point of the 

resistor 8, it is apparent that the drum 25 should 

revolve at a rate such that reSistor 8 IS caused 65 

to rise at a rate equal to the normal accelerating rate of the car C As stated, I accomphsh 

this by employmg the spring 89, wluch may be 

regulated to permit any desired rate of movement. of the drum 25 70 

Accordingly, when the car attains its full runrung speed, the a.rm 21 carrying the resistor 8 

is m the position shown by the dotted lines, the 

element 13 of the governor device is in its dotted 

line po&t1on and brush member 18 16 m engage- 75 

• 
.. 

REF ID:A67827 

S,006,890 s 

ment with the resistor 8 at approximately its 

centre.I poJnt 

The position of resistor 8 then, is fixed as long as the full running circuits of the motor are 5 mamte.med The brush member 18, however, 

me.y have a slight up e.nd down movement in 

accordance with val"lations in speed of the elevator motor EM For example, if the motor attains a speed 311:;htly m excess of its predeter10 mined running speed, the brush member 13 rJ.Ses 

slightly and inserts an additionaJ portion of the 

reSlStor 8 m the circuit of the separately excited 

generator field wmd.lng GF, thereby causing the 

generator voltage to drop and decrease the speed 

16' of the elevator motor EM Conversely, if the 

speed of the elevator drops below its predetermined value, the member 13 falls sbghtly, thereby decreasing the portion of resistor 8 in the 

circwt of the wmdl.ng GF, and causes the mo- 20 tor to accelerate a proportional amount If the 

value of resistor 8 is properly proportioned, a shght variation of the elevatoi motor speed from 

its predetermined runrung speed may be made 

to cause a sufficient ve.r1at1on in the iesi.stance 

25 m the circuit of the wmd.lng GF to cause the 

generator \oltage to va1y enough to bring the 

motor speed back to, and slightly on the other 

side of, the predetemuned i.peed In tllls v. ay the 

device l will operate similarly to voltage regu-

:,o le.tors of the vibrating type, usually applied to 

power systems The variations, of cou1se, me.y 

be made as small as desired by incree.smg the 

sensitivity of the regulating device 9 

If, now, 1t is deSJred to stop the car. the oper35 a.tor may center his car switch to thereby render 

the automatic stopping means effective for operation Centering the car switch Ci. completes 

a oircwt to the coil of hlgh speed up-d.lrection 

mductor relay 2LU, whlch circwt extends from 

40 lme conductor LI through conductor 60, con- tact members 61, 62 and 125 of the car switch 

cs. conductors 126 and 121, contact members 

a of up-direction switch I, conductor 128, the 

c01l 129 of 111ductor relay 2LU and conductors 

130, 131, and 96 to line conductor L2 As the 45 car m 1ts movement up the shaft brings the 

inductor relay 2LU to a position opposite the as- s001a.ted inductor plate 2LU', the armature of 

the relay will be actuated to open the contact 

members 113 The opening of these contact 50 members interrupts the circuit to the coil of 

accelerating relay 4, the consequent opening of 

whlch relay reinserts a portion of resistor 84 mto 

the circuit of the fleld windmg GF, thereby caus- ing the elevator motor to decelerate 5;; The closing of contact members d of relay 4 

completes a. circuit to the cam motor CM. which 

circuit extends from line conductor LI through 

conductor 60, the contact members 61, 62 and 

125 of the car switch Cs, conductors 126 and 132, 60 "the now closed contact members of voltage relay 

&, conductor 133, contact members d of relay 4, 

conductor 134, thence m parallel relation 

through the field wmdmg CMF and armature 

65 C?o.il', of motor CM, and conductor 136 to line 

conductor L2 

As i.tated, in the description of the apparatus. 

the voltage ielav 6 is interposed m the cam motor 

circuit in 01der that it may interrupt. this cn7.0 cwt wlule tile car is stationaiy The coll of ielay 

& is.shown as connected d.lrectly acioss the terminals of the generator G, by way of conductors 50 

and 59 and the voltage supplled it is therefo1e 

proportional to the speed of the elevator motor 

7.a BM. The-coli IS so designed tnat it w1.U nQt act11ate the relay unless the speed of the car is in 

excess of its intermediate speed, but will maintain 

the relay in the actuated position until the gen· 

era.to1 volta.ge drops to a very low value, which 

occws after the expiration of the slow down pe- 6 

riod, or after the brake has been set Smee the car is running at its run speed, relay 6 is in the 

actuated position 

Be1ng supplied with pawer the motor CM starts 

to rotate in a dll'ection to drive the drum 2& in a 10 

clockwise direction to thereby ra.LSe the roller 28, 

ns determined by the cam surface 24, and mov~ 

the resistoi 8 in a downward dl.l'ect1on As the 

ca1 deccleiates, the positron of the member .JI 

will also be lowered If the rate at which the de- 16 

celeration ot the car ca.uses the member 13 to be 

1owe1.ed is equal to the rate at which the cam suiface 24 causes the rtsIStor B to be lowered, 

it w1ll be apparent that the brush member II will 

remain m engagement w1th the resistor 8 at the 20 

seme contact pomt If, however, the car C de· 

c..elerates at a g1eatc. or lower rate than that 

prescr!bed by the curves of Flg 2, the brush 18 

v.1ll move relatively to the res1stor 8 and \'&l"Y 

the generator voltage, and hence the motor speed, 26 

\llith the 'ibratmg movement described a.bov.e 

The closing of the contact member c of relay 

4 completes a circwt to the coll of inductor reJay 

ILU, which circuit extends as described for tbe 

coll of mductoi ielay 2LU to the pomt l31, thence 39 

by way of conduct01· 138, the coil 138 of inductor 

relay ILU, conductors 140 and 141, the contact 

members c of relay 4 and conductor 142 to hne 

conductor L2 

As the car in its movement up the shaft brings 3a 

the mductor relay ILU to a. p0S1t1on opposite its 

associated mduct01 plate ILU'. the armature of 

relay ILU is actuated to open its contact membeis 

I 00, thereby mteirupting the circwt to the coll Of 

relay 3 and causing tlus relay to open the contact '0 

members a and b and to close the contact mem- bers c and d The opening of contact members 

b reinserts the remaining portion of reSlstor t4 

into the circuit of the winding GF, thereby re- ducing the excitation of the generator a.nd caus- 45 

Ing the elevator motor to further decelerate. 

As described m connection with the first slowdown operation, the resistor 8 IS further lowered 

under the influence of the roller 23, and the ~ement 13 of the goveinor is lowered by res.son Qf 50 

the deceleration of the car, the vibrating ac· tion being irut1ated if the relative positions Qf 

these elements \'ary 

The closing of contact members c of relay 3 

completes a cncuit for the coll of stoppmg mduc- 6G 

tor relay SR, which Cl.l'cuit extends from lipe 

conductor LI through conductor 60, the contact 

members 61, 62 and 126 of car switch Cs, con- ductors l?G and 143, the coil 144 of inductor relay 

SR, conductor 145, contact members c of relay 60 

3, conductors 146, 126 and 121, contact members 

d of up-direction switch I, conductor 128, the coils 

oI inductor relays 2LU and ILU m parallel, and 

conductors 130 and 131 to line conductor L2. 

As the car continues in the upward direction 115 

nnd brmgs the inductor relay SR opposite its 

associated inductor plate SR', the armature of 

the relay SR is actuated to open the conta.ct mem· hers 13, thereby interrupting the circwt to the 

coll 65 of up-direction switch I The opening of 70 

up-direction switch I interrupts the c1rcwt to the 

generator field winding and the brake <noi 

shO\vn> wluch therefore operates to brmg the car to rest This last operation takes place when the 

c~r ls moving at a. rate of, for example, abput 2JI 'l& 
REF ID:A67827 

6 9,0015,890 

to 30 feet per minute A variation in the speed 

of the car of even 1 or 2 feet per minute, therefore, makes a pioportionately large difference m 

the speed of the car at this time, and, unless cor- . 5 rected, leads to stoppage of the elevator car at 

pomts other than level with the fioor 

The value of my invention, therefore, becomes 

particularly apparent at thIS pomt in the operation of the elevator car, smce the vibrating action 

IO of the member 13 with respect to the reSistor 8 

so controls the field of the generator G as to cause 

the speed of the elevator motor EM to be a predetermined value at the time the brake <not 

shown> is set to bnng the car to a stop 

16 The action of the device is of value when the 

car lS runnmg at full speed, as described hereinbefore, Since the field of the generator is so controlled as to cause the speed of the elevator motor to be of a predetermmed value upon initiation 

20 of deceleration, thereby conditioning the car to 

follow the prescribed curve in decelerating 

The operung of contact ;members a on up-direction switch, it wlll be noted, interrupts the 

circuits to the coils of all of the inductor relays 

25 The opening of the contact members 13 of 

stopping inductor relay SR also interrupts the 

circuit to the coil 68 of the latching device 69, 

movement of which is restrained, however, until 

the drum 25 has revolved to such a point that the 

30 device 69 can engage the latch portion BB of the 

drum 25 It will be remembered that the coil 

119 of latchmg device 120 is deenerg1zed when 

the contact member 62 leaves the contact member I 06 of the car switch CB, but that this la.tch35 mg deVIce has no effect on the movement of the 

drum 25 when rotating m the clockwise direction, since it rides over the latch portion BB of 

the drum 25 

As previously described, the voltage relay 6 re40 mams in the actuated position untll the genera.-

tor voltage drops to a value corresponding to an 

elevator motor speed lower than the slow running speed Therefore, the circuit to the cam 

motor EM is ;mamtained untll after the la.tchmg 

45 device 69 engages the latch portion 88 of the 

drum 25, but is interrupted shortly thereafter 

in order that the motor CM may not consume 

power while the elevator car is standing at a 

:D.oor It will be apparent that when the latch50 ing device 69 has engaged the latch portion 88 

of the drum 25, motion of this drum under the 

in:ftuence of the sprmg 89 is restrained until such 

a time as the elevator car is again started 

Through this arrangement, then, while the car 

55 is standmg at a fioor, both the member 13 and 

the resistor 8 are in their lowest positions 

When, however, the elevator car is started m 

either direction, the latching device 69 lS retracted to permit the spring 89 to change the po60 s1tion of resistor 8 m substantial syn.chroDlSm 

with the change m pOSitlon of the element 13, 

caused by the change in speed of the elevator 

car. 

In an elevator system ha..vmg an operatmg 

65 speed as high as SIX hundred feet per mmute, 

such as I have illustrated, it is possible to accelerate the car to full speed only if a. movement of 

two or more floors is con~plated, since it reqwres approximately the distance between two 

70 successive floors to either accelerate the car to 

full speed, or to decelerate it from full speed 

If, then, it is desired to make stops at succeSSive 

fioors, the car must be accelerated to only its 

mtermedlate speed In this event, the motion 

1& of the element fa w111 be restr1cted and it is neeessary to -correspondingly limit the movement 

of the resistor 8 I accomplish this by limiting 

the rotation of the drum 25 to a. poSition determmed by the latching device 120 

It will be remembered that the coil 119 of 5 

latchmg device 120 is not energized until such 

a time as the car switch CB is moved to its extreme poSition Therefore, if the car switch Cs 

is ;moved to a position to accelerate the car only 

to its mtermedia.te speed, thIS coil wlll not be IO 

energized and, as a consequence, when the drum 

25 has rotated to such an extent that the latch 

portion 88 thereof is engaged by the latching device 120, further movement of the drum 25 and, 

hence, of the resistor 8 is restrained 15 

The regulating action obtained through the 

device 1 when the car is running at full speed is, 

therefore, obtained precisely m the same manner when the car is opera.ting at intermediate 

speed 20 

To brmg the car to a stop from intermediate 

speed, the operator, of course, centers the car 

switch as described before, and, at predetermined 

intervals, through the action of inductor relays 

ILU and SR the car is decelerated and brought 25 

to a stop by the deenergization of relay 3 and of 

up-dnection switch I, and setting of the brake 

<not shown> 

In this operation it is necessary that it be 

posSible to energize the cam motor CM at the 30 

time at which the relay 3 is deenergized I have 

proVIded, therefore, a second circuit for the motor CM extendmg from line conductor LI to line 

conductor 126, as previously described, thence 

through conductor 141, the contact members of 35 

voltage relay 5, conductor 148, the normally 

closed contact members a of relay 3, conductor 

149 and thence through conductor 134, as previously described The coil of relay & is energized 

by way of the same circuit through which relay 40 

6 is energized, but is operably responsive to a 

voltage corresponding to an elevator speed slightly lower than intermediate speed If the elevator lS decelerated from high speed therefore, the 

motor CM is controlled by the relays 4 and 8, 4j 

and, if decelerated only from intermediate speed, 

is controlled by relays 3 and 5 

Therefore, the motor CM starts to revolve the 

drum 2 5 as soon as relay 3 is deenergized through 

the action of inductor relay ILU 50 

Smee operation in the down-direction is in 

all respects similar to operation m the up-direction, with the exception that down-direction 

switch 2 replaces up-direction switch I, that the 

inductor relays 2LD and ILD replace inductor 55 

relay 2LU and ILU, and the car switch Cs IS 

moved in the clockwise direction instead. or the 

countei -clockwise direction, it is not believed 

necessary to describe such operation in detail 

It will be seen from the described embodimen\ 00 

of my invention, that I have provided a. motor 

controlling device whereby any variation from a 

predetermmed running speed of a motor may 

be utilized to correct for such variation, and cause 

the motor speed to return to the predetermined O:i 

value As described, the device may be employed 

under condlt1ons of desired constant speed, and 

may also be employed under conditions of desired 

variation m speed accordmg to any prescribed 

schedule of var1at1on Through my invention, 70 

therefore, it is possible to attain a very precise 

motor regulation durmg all conditions of operation 

It is to be understood that the present embodiment is merely illustrative, and that I do not 75 
• 

REF ID:A678. 

- 2,006,890 '7 

desire to be lnnited to the details thereof except 

as defined m the appended claims 

I claun as my invention 

1 In a control system for an elevator car, m.>-

ii tive means for :.aid car operable to cause said car 

to accelerate f1om zero speed to an inte1med1ate 

speed, and from said intermediate speed to a 

higher speed, and to decelerate from said inte1 - mediate speed and said highe1 &peed to zero speed, 

10 means for cont1oll111g said motive means. means 

operable from one p::>sihon to another pos1t1on m 

accordance with a predeterm.med rate at which 

said car should decele1ate from said higher 

speed to zero speed, and operable between an in1.; termed1ate position and said other posmon m accordance v.1th a predetermined rate at \'/h1ch said 

car should decelerate from said inte1m::d1ate 

speed to zero speed, means cpei:iolc t:> return 

said operable means past said mtc1medmte po20- s1tion to said first position afie1 said deceleration 

period, means operable m accordance with the 

actual rate at which sa1d car decelerates for cooperating with said first named operable means 

when said predetermined rate and s:ud actual 

25 rate differ to cause said control means to va1y said 

actual rate to decrease sa!d difference, restiaming 

means operable when said control means a1 e actuated to cause said car to accelerate to said mtermed1ate speed to prevent said ieturnmg means 

30 from moving said firr.t pamed ::ipe1 able means past 

said intermediate position, and means operable 

upon movement of said cont1ol means to accelerate sa1cl car to srud higher c;peed to iender said 

restraining means me:lfective 

35 2 In a motor-control system, a motor, a source 

of power for driving said motor, sw1tchmg control 

devices for cont1olhng said source to effect a predetermined rate of change of the speed of said 

motor, in combination with a regulating device 

40 comprising two cooperating elements, means defining predete1mined paths of movement for each 

of said elements, means for determining the position on the associated path of one of said elements in accordance with the actual speed of 

45 said motor, means for causing movement of the 

other of SBJ.d elements along the associated path 

at a rate proportional to saJ.d predetermmed rate 

of change of speed of said motor, and sw1tchmg 

mechanism controlled in accordance with th~ 

50 relative poSitions of said two elements and effective, in the event that the actual rate of change 

of speed of said motor differs from said predetermined rate, to control said source to reduce said 

difference 

55 3 In a motor-control system, a motor, a source 

of power for driving said motor, switching control devices for controlhng said source to effect a 

predetermined rate of change of the speed of said 

motor, in combination with a regulating device 

60 comprising two cooperatmg elements, means defining predetermined paths of movement for each 

of said elements, means for determ1mng the position on the associated path of one of said ele69 ments in accordance with the actual speed of said 

motor, means for causing movement of the other 

of said elements along the associated path at a 

rate proportional to said predetermmed rate of 

change of speed of said motor, switchmg mech7& amsm controlled m accordance with the relative 

positions of said two elements and effective, in 

the event that the actual rate of change of speed 

of said motor differs from saJ.d predetermined 

rate, to control said source to reduce said dif78; te11e11.ce, and means responsive to the actuation of 

sa.Jd control devices for rendering the moving 

means for said other element effective 

4 In a control system for an elevator, a hoist 

motor for said elevator, a source of power for said 

motor compriSing a supply generator having field · :> 

magnets, electrical connections between said motc..r and said generator, control means operable to 

control the exc1tat1on of said field magnets to effect a p1edetermined iate of change of the speed 

of said motor, said control means comprising a 16; 

regulating device having an element operable m 

accordance with said predetermined i ate of 

change of moto1 speed, a second element operable 

m accordance with the actual rate of change of 

motor speed, switching mechanism controlled by 1-5 

both of said two elements and operable. m tt1e 

ei.ent said actual and predetermined rates d1:fl'er, 

to vary the exc1tat1on of said field magnets to reduce said difference, means responsive to the pos1i1on of said elevator, and selectively operable 20'· 

means to render said control means responsive to 

said position responsive means 

5 In a control system for an elevator, a hoist 

motor for said elevator, a source of power for 

duvmg c;rud motor comprismg a generator hav- 25 

ing field magnets electrical connections between 

said motor and said generator, control devices 

actuable to vary the excitation of said field magnets to effect a predetermmed rate of change of 

the speed of said motor, comprising a regulating 30 

device having two relatively moi.-a.ble elements, 

means for ope1atmg one of said elements at a rate 

proportional to said predetermined rate of 

change of motor speed, means for operating the 

other of said two elements at a iate propo1 t1onal 30 

to the actual rate of change of motor speed, 

switching mechanism controlled in accordance 

with the relative pos1t1ons of said two elements 

and effective, in the event that said actual and 

p1edetermmed rates differ, to vary the excitation 40 

of said field magnets to reduce said difference, 

means responsive to the position 01' said elevator 

and means responsive to the actuation of said 

control devices for rendering said first named 

operating means responsive to said position re- 45 

spons1ve means 

6 In a control system for a motor, a source 

of power for dnv1ng said motor comprising a generator having field wmdmgs, electrical connections between said motor and said generator, a 50 

circuit for said field windings, a plurality of sections of resistance, and switching mechanism operable to sequentially include certain of said sections of resistance in the circuit of said field 

winding to reduce the speed of said motor at a 55 

p1edetermined rate, in combination with a regulating device havmg two cooperating elements, 

means for controlllng one of said elements in accordance with the actual rate of change of the 

speed of said motor means for controlling the 60 

other of said elements in accordance with said 

predetermined rate. and means controlled by 

both of said two elements and effective, in the 

event that said actual and p1 edetermmed ra1 ec; 

differ, to include or exclude others of said sec- 65 

tions of resistance in and from said cilcwt to 

thereby maintain said actual rate at substantially said predetermined value 

7 In a control system for an elevator car operable past a floor landmg, a hoisting motor oper- 70 

o.t1vely connected to said car, a source of power 

for driving said motor compnsmg a generator 

having field magnets. electrical connections between said motor and said generator, means to 

control the excitation of said field magnets to '11· 
REF ID:A67827 

8 2,006,890 

control the speed of movement of sa.J.d elevator 

car comprlSlng switclung mecharusm sequentially 

operable as said car approaches said :floor to gradually reduce the excitation of said field magnets 

6 to cause said car to retard at a predetermmed 

rate and stop accurately level with said :floor, 

m comb1nahon with a regulator having two cooperatmg elements, means to control one of said 

elements m accordance with the actual rate of 

10 retardation of said elevator car, means to control 

the other of said elements in accordance with 

said predetermmed iate of retardation of said 

car, and switchmg mecharusm controlled by both 

of said two elements and effective, m the event 

16 that said actual and predetermined rates differ, 

to vary the excitation of said field magnets to 

reduce said difference 

8 In a control system for a motor, a sou1ce of 

power for driving said motor comprising a supply 

20 generator having field magnets, electrical connection& between said motor and said generatoi , and switching mechamsm operable to vary the 

excitation of said field magnets at a predetcrmmed rate to va1y the speed of said motor at a 

25 corresponding rate, m combmation with a regulator effective to mamta.in said rate of change 

of motor speed at substantially srud predetermmed value, sa.d regulator compnsmg two coope1 atmg elements, means for controllmg one of 

30 sa.J.d elements m accordance with the actual rate 

of change of motor speed, means for controllmg 

the other of saJ.d elements m accordance with 

said predetermined rate of change of motor speed, 

and switching means controlled by both of said 

3:; two elements, and effective, m the event that said 

actual rate exceeds said predetermmed rate, to 

tempararlly vary the excitation of said field magnets by an amount sufficient to reduce said actual 

rate to a value lower than said predeteimmed 

40 rate, and effective, m the event that said predetermmed rate exceeds said actual iate, to temporarily vary the excitation of said field magnets by an amount sufficient to mcrea!>e said 

actual rate to o. value higher than said predeter45 mmed rate 

9 In a control system for an elevator car operable m a hatchway, a motor for movmg said car, 

a source of povvei for said motor, and contiol 

mechamsm to control said source to decelerate 

50 sa.J.d motor and to cause the speed of said motor, 

dur.ng deceleration, to follow a predetermmed 

succesi.ion of values with respect to the travel of 

said car m said hatchway, said contiol means 

comprismg a regulator, means for differentially 

55 controllmg said i egulator m accoi dance with the 

actual speed of said motor and said predetermined succession of values, said regulator being 

effective, m the event the actual speed of said 

motor differs from said predetermined succession 

60 of values, to contiol said source to ieduce said 

difference, and means comp11smg a control 

switch opeiable to render said contiol mecharusm effective 

10 In a. contiol system for an elevator car op65 eiable m a hatchway past a pluiallty of floors, a 

motor for said car, a source of powei for said motor comprismg a generator havmg field wmdmgs, 

and slow-down mechamsm to control the excitation of said field wmdmgs to decelerate said 

70 motor and to cause the speed of said motor durmg deceleration, to follow a predetermmed succession of values with respect to the travel of 

said car m said hatchway, said means comprismg 

a regulator, means for di1Ierent1ally controllmg 

115 said regulator in accordance with said succession 

of values of motor speed and the actual speed of 

said motor, said regulator being effective, m the 

event the actual speed of said motor differs from 

said predetermined succession of values, to vary 

the excitation of said field wmdmgs to ieduce 5 

said difference, and means compusmg a. selectivel3' operable control switch for rendering said 

slow-down mechanism effective to decelerate said 

motor upon the approach of said elevato1 to any 

cf said floors IO 

11 In a control S3'stem for an elevator car ope1able past a plmality of :Hoers, a motor for movmg said elevator, a geneiator for supplymg power 

to said motor, means to control the excitation of 

said generator to cause said motor to stop said 15 

car at any of said floors, and to cause the speed 

of said mot01, durmg deceleration, to pass 

through a predeteimmed succession of values 

with respect to the position of sa1d car m advance 

of said floor, compusmg regulatmg means hav- 20 

mg tvvo cooperatmg elements, means for controlling one of said elements m accordance with the 

actual speed of said motor, means for controlbng 

the other of Sa.J.d two elements m accordance 

with said p1 edetermmed succession of values of 26 

motor speed, means controlled by both said elements, and effective, m the event the actual speed 

of said motoi differs from said predetermined 

succf'ssion to vary the excitation of said generator 

to ieduce said difference, and selectively operable so 

means to render said first named control means 

effective to cause SSJ.d ca.r to stop at a.ny selected 

one of said floors 

12 In a control system for an elevator car opei able past a floor a motor for moving said eleva- 35 

toi, a generator for supplymg power to said motor, slow-down mechanism to control the excitatmn of said generator to cause said motor to stop 

said car at said floor, a.nd to cause the speed of 

said motor durmg deceleration, to pass through 40 

o piedetermmed succession of values with respect 

to the position of said car in advance of said floor, 

comprismg regulatmg means havmg two cooperating elements, means fer controllmg one of said 

elements m accordance with actual speed of said 45 

motor, means for controllmg the other of said 

t\vo elements, in accordance with srud predetermmed succession of values of motor speed, and 

means controlled by both said elements, and effective, m the event the actual speed of S8ld motor 60 

differs from said predetermmed succession to vary 

the excitation of said generator to reduce said 

difference, means responsive to the POSltion of 

said car with respect to said fl.oor, and selectively 

operable means for rendermg said slow-down 55 mechanism respon51ve to said position responsive 

means 

13 In a control system for a motor, a source of 

power for drivmg said moto1 comprismg a generator havmg field windings, electncal connec- 60 

t10ns between said motor and said generator, a circuit for said field wmdmgs, a plurahty of sections 

of re'llStance associated with said circwt, and 

switching mecharusm operable to control said resistance to vary the excitation of said field wind- 65 

mgs to reduce the speed of said motor at a. predetermmed rate, m combmation with a regulatmg device having two cooperating elements, 

means for controllmg one of said elements solely 

m accordance with the actual rate of change of 70 

the speed of said motor, means for controlhng 

the other of said elements m accordance w1th 

said predetermined rate, and means controlled 

by both of said two elements and effective, m the 

event that said actual and predetermined rates 76 
• 

REF ID:A67827 

8 1001S1890 9 

differ, to further vary the excitation of said fleld 15 A control system. for an elevator car comwmdmgs to thereby maintain said actual rate at prising a hoistmg motor, a. generator for supplysubstantlally said predetemnned value ing pawer to said motor, control means for said 

14 A control system for a.n elevator car com- generator compr15mg regulating mechanism dis5 prising a. holSting motor, a. genera.tor for supply- posed to control the rate of change of speed of 5 

ing power to said motor, control means for said said motor, a pilot motor associated with said 

generator compnsmg a pilot motor, means re- regulator, means respansive to the pasition of 

spons1ve to the position of sa.i.d car for actuating said car for actuating said control means to desaid control means to ca.use said genera.tor to celerate said motor, sSJ.d la.st named means com10 decelerate said hoisting motor, said last named prising means to start said pilot motor. 10 

means compr18lng means to start said pllot motor. JAMES DUNLOP . 
June 25, 1935. 

t., 

77 

Ca 

c 

60 

7Z 

Fig I. 

REF ID:A67827 

J DUNLOP 

MOTOR CONTROL SYSTEM 

Filed Nov. 13, 1929 

128 

/,,/"Fl 

Z/ 

2,005,890 

2 Sheets-Sheet l 

H 

80 

INVENTOR 

James JJunlop 

,, 
June is, 1935. 

I 

REF ID:A67B27 

J DUNLOP 

MOTOR CONTROL SYSTEM 

Filed Nov 13, 1929 

2;005,890 

2 Sheets-Sheet .2 

111nu1J .14:J 1aa..:1 u1 paarls JOJTMllf.3 

INVENTOR 

James .Dunlop. 

0 

,,/ 

.. 

.r