US1771459A

US1771459A - Control system

Info

Publication number: US1771459A
Application number: US288637A
Authority: US
Inventors: Hymans Frederick
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1926-01-12
Filing date: 1928-06-27
Publication date: 1930-07-29
Anticipated expiration: 1947-07-29

Description

July 29, 1930.

F. HYMAN S CONTROL SYSTEM Original Filed Jan.. l2', 1926v 2 Sheets-Sheet l FIG.

INVENTOR ATroRNeY July 29, 1930. F. HYMANS CONTROL SYSTEM l 2 Sheets-Sheet 2 original Filed Jan. 12, 192e Cil Patented July 1930 UNITED STATES PATENT OFFICE y FREDERICK arms, or YoNxERs, NEW YORK, assiGNoR'ro'o'ris ELEvA'roR ooit-y PANY, or JERSEY crrY, NEW JERSEY, A coRroRarxoN or NEW JERSEY CONTROL SYSTEM Original application tiled January 12, i926, Serial No. 80,763. Divided and this application tiled .Tune 27,

v 1928. Serial No. 288,637. K

The invention relates to control systems, and particularly to control systems for elevators.

This application is a division of application Serial No. 80,7 63 filed January 12, 192?.

In elevator systems in which the car is brought to a s top automatically at a landing, it is important that the speed of the car, during` the stoppin operation,y be accurately u', controlled if goo stops are to be made. This is particularly true in systems in which push button control is'employed for causing the automatic slow-down as well as the final stop and in those in which the starting of the car is under the control of an operator while the slow down and stop is automatic.

It is advantageous in such systems to employ a variable voltage direct current generator for supplying power to the elevator motor. The control of the field strength must be such that the E. M. F. generated may be rapidly brought to a proper value to cause the elevator motor to run at a suitable speed from which an accurate stop may be made. The time constant of the generator field during the slow down and stopping operations is g an important factor, especially where a generator is used Whose field has a large time constant. Onefeature of the invention resides inv arranging and connecting the generator field windings so that the'time required forthe generator field to adjust itself to the desired strengths is minimized during periods when a low voltage is desired. y

Other features and advantages will become apparentfrom the following description and. appended claims.

. The invention is particularly suitable for use in connection with self levelling elevator systems as in such systems it may be necessary to reverse the direction of movement o f the car as well as to accelerate or 'retard 1t or to move it up or down in making a stop. While the invention is applicable to other elevator systems, principally those in which automatic stopping is emp oyed, it will be described, by way of illustration, as embodied in a system in which self levelling mechanism is provided.`

In the drawings: y

Figure 1 is a diagram of an elevator control system;

Figure 2 is a fragmental schematic view of a portion of the elevator system, illustrating particularly the manner in which the generator field windings are controlled during the levelling operation, and

Figure 3 is a portion of a diagram similar to Figure 1 showing a slightly different arrangement of the control system.

Referring'to Figure 1, no attempt is made to show the coils and contacts of the various electromagnetic switches in their associated positions, a straight diagram being employed wherein the coils and contacts of the various switches are separated in such manner as to render the circuits involved rela- I tively simple. Also the parts of other switches and apparatus are separated in the interest of simplifying the diagram. For a clearer understanding of the invention, the stationary contacts of' the switches are illustrated in cross section. v

The motor generator set'comprises a driving motor 11, illustrated for convenience of description as of the direct current type, and a variable voltage direct current generator 12. The armature of the driving motor is designated 13 and its field winding 14. The armature of the generator is designated k15, its

-series field' winding 16, its major separately generator field and therefore the voltage'applied to the elevator motor armature during car switch operation. Another resistance 28 is provided for controlling the strength of the generator field during levelling operation. resistance 29 controls the strength ot' the elevatormotor field during different conditions ico of operation. 30 is the release coil for the elevator motor electromagnetic brake. This coil is provided with

discharge resistances

31, 32 and 33 for controlling the application of the brake under different conditions of operation. 34 and 35 are the up slow speed contacts and the down slow s ed contacts respectively of the levellin' switch, the levelling switch up and down ast speed contacts being designated 36 and 37 res ectively. 38 is the armature and 40 is the eld windin of the motor 41 for moving the rollers o the levelling switch into position to clear the levellin cams. 42 is the armature and 43 is the tiel winding of the door control motor 44. 45 and 46 are the direct current supply mains. 47 is a double pole knife switch for connecting the system'to the supply mains. In order to suit the type of diagram employed, the blades of this switch are shown separated. The car switch is designated as a whole by the numeral 48. 50 is the safety switch in the car. The series of door contacts are indicated by a single set of contacts 51. The gate contacts are indicated as 52; Thel various safety, limit, stop and emergency switches are omitted in order to simplify the description.

The electromagnetic switches have been designated as follows:

A--potential switch,

B-up main direction switch,

C-down main direction switch,

D--iirst accelerating switch,

E-second acceleratlng switch,

-F--series field switch,

G-series lield relay,

l-l-main brake and field switch,

J-door control motor switch,

K-door control motor maintainingrrelay,

L-tield control switch,

M-maintainin relay,

N--sequence re-ay,

@naccelerating rela P--hard brake switc R--levelling control relay,

Lid-up levellin direction switch,

LgJ--down leve 'ng direction switch,

Lil-levelling brake and field switch,

LF-fast speed levelling relay.

Throughout the description which follows, these letters, in addition to the usual reference numerals, will be applied to the parts of the above enumerated switches. For example, contacts B 111 are contacts on the up main direction switch, while actuating coil A 53 is the coil that operates the potential switch. The electromagnetic switches'are shown in their deener 'zed positions. Reactances are similarly desi ated by the characterl X.

Upon the c osing of the knife switch 47 the driving motor 11, elevator motor field winding 22 and potential switch actuating coil A 53 are ener the circuit for coil A 53 being throug safety switch 50. The driving motor starts in operation, bringing the generator 12 up to full speed. The series field `winding and starting means for the 'driving motor are omitted to simplify the description. With the elevator motor at rest, the current supplied to its field winding 22 is reduced by section 54 of resistance 29, providing what maybe termed a standing field. The circuit for the elevator motor field winding may be traced from the lefthand blade of switch 47, line 55, by way of line 56 through field winding 22, resistance section 54 and second accelerating switch conpotential switch, upon o eral-ion, causes the engagement of conta'cts 60 and A 61, preparing the circuits for the generator separately excited field winding, the electromagnetic brake release coil and the control circuits. The condition of the circuits so far described might'be termed normal.

Referring briefiy to Fi ure 2, the car switch 48 comprises a

set o u contacts

62, 63, 64, and 66 and a set of

own contacts

67, 68, 69, and 71. A contact segment 72 for bridging the contacts of each set is mounted on the segmental support 73 .of insulating material. A cam 74gis formed on the support above the pivot oint 75. The cam is ormed with a centra y disposed depression 76 into which the o rating roller 77 of the gate and door switch 8 extends with the car switch in neutral or off position. The switch 78 is pivoted at 80 so that movement of the `car switch in either direction causes the engagement of the switch contacts. The car switch is operated by means of a control handle 81. It is preferred to provide centering sprin (not shown) on the car switch to cause 1t to be returned to 0H position when released. b the operator.

Referring back to igure 1, assume that the system is designed for an installation of several floors and that the car is at rest at the first floor with the gate and door open. In the starting o the car switc a slightinitial movement to eect the closure of the gate and door switch 78. For convenience of description, this switch is arran ed to complete a circuit for ration, the operator first gives lll thedoor contro motor switch actuating coil J 82. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 83 through coil J 82, resistance 84 and switch 78, line 85, switch 50 line 86, line 58, to. .the right-hand blade of switch 47 The gate control motor switch, upon operation, causes infra-use the engagement of contacts J 87, completing the circuit for the door control motor 44. This circuit may be traced from the lefthand blade of switch 47, by way of line `through contacts A 60, by way of line 88 mechanism, as for example through linkage,l

90, to move valve 91 for gate engine 92 to gate closed `position and to withdraw the re tiring cam 93 from` engagement with the roller provided on the end of the door engine valve lever 94. The lever 94' is operated by a spring to move valve 95 for the' door `en- .The gate If either coil is energized ahead of the other,

gine 96 to door closed position. and door engines operate` through mechanism not shown to close the car gate 99 and hatchway door 109. It is to be 'understood that a door is provided in the hatchway for each landing. y

Referring back to Figure 1, if the operator, after he zhas closed the gate and door,

desires to open them, or if he desires to arrest their movement, he may do so by releasing the car swltch to return to off position. This causes the opening of the gate and door l switch 78 with the consequent deenergization of coil 'J 82 andthe separation of contacts J 87. In this manner, the circuit for the motor 44 is broken. The spring 97, shown in Figure 2, operates upon the deenergization of motor 44 to move valve 91 and, through cam 93 and lever 94, valve 95 into positions to `cause the reverse operations of the engines 92 and 96 to open the gate and door. Obviously other forms of power operated gate and door mechanisms, such as electric in lieu of pneumatic, may be employed without departing'` from the spirit of th'e present invention.

Assuming that the gate and doors are closed, the gate contacts 52 and door contacts 51 are in engagement. The operator may now move the car switch to full operated position to start thecar in the up direction. It is to be noted-that the gate and door switch 78 remains in closed position so long as the car switch is moved out of neutral position. Upon the engagement of contact segment 72 and contact64, circuits aresimultaneously completed 'for the oppositely wound coils N 98 and N 100 of the sequence relay, actuating coils R 240 of the levelling control relay H 101 of the main brake and field switch and B 102 of the up main direction switch being in the circuit for coil N 100. The engagement of the contact segment and contacts 65 and 66 prepares circuits for the actuating coils of the accelerating switches.

The circuit for coil N 98 of the sequence relay may be traced from the left-hand blade of switch 47, by way of line 55 through contacts 60,` by way of line 103 throu h coil N 98 and resistance 104, contacts 62 an 64 of the car switch, b way of line 105 through contacts C 106 o `the down main direction switch line 85, to the right-hand blade of switch 47 as above traced. The circuit for coil N- ma be traced from the left-hand blade of switc 47, by way of line 55 through contacts A 60, by way of line 107 through door contacts 51, gate contacts 52, sequence relay contacts N 108, andcoils R 240, N 100,

ygate and doorsbefore starting the car. Coils N 98 andN 100, bein differentially wound, oppose each other, w en energized simultaneously, to prevent the operation of the relay.

or 'ifeither coilalone is energized, contacts N 108 separate, preventing the starting 0I" the car. If either the gate contacts 52 or any of the door contacts 51are separated at the time that car switch segment 72 engages contacts 64, coil N 98 aloneis energized, resulting in the separation of contacts N 108. The separation of contacts N 108 prevents the energization of coil N 100, maintaining the s equence relay "operated, and of coil B 102, preventing the' operation of the up main direction switch to effect the starting of the car. The ate and door switch 78, therefore, is close by the vinitial movement 'of the car switch so that the gate and door contacts may be closed before the engagement of segment 72 and contact 64. However, if the car switch is moved into position where segment 72 engages contact 64 before the closure of the door and gate contacts, the sequence relay Thus it is impossible to start the car on the door or gate contacts.

Assumin that the se uence relay has operated, Iin or er to start t e car the car switch is returned to a position with segment 72 dis- -inA the circuit for the actuating coils of the levelling direction switches. The purpose of this arrangement will be described later.

It is preferred to provide the main direction switches with a. mechanical interlock to prevent their simultaneous operation. Such an interlock may be of the form of a walking beam pivotally mounted for engaging catches on th'` armatures of thesel swiChes. Upon operation of the up main direct-ion operates to prevent the starting of the car.y

switch in response to the energization of its actuating coil B 102, contacts B110'separate and contacts B 111, B 112 and B 1133 engage. The separation of contacts B 'breaks the circuit leading from the car switch down feed contact 69, contacts B 110 and the corresponding down direction switch contacts C 106 serving as electrical interlocks as is well understood in the art. The engagement of contacts B 113 prepares the circuit for the up main direction switch holding coil B115 and the main brake and field switch holding coil H 116. The engagement of contacts B 111 and B 112 completes acircuit for the generator major and minor separately excited field windings. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 109 through resistance 27 and contacts B 111, by way of line 117 through field control switch contacts L 118, through the minor separately excited field winding 18, by way of line 120 through contacts L 121 and the major separately excited field Winding 17, by way of line 219 through contacts B 112, by way of line 58 through contacts A 61, to the right-hand blade of switch 47.

The main brake and field switch H operates simultaneously with the main direction switch B. Switch H,A upon operation, causes the separation of contacts H 119, H 122 and H 123 and the engagement of contacts H 124,

H 125, H 126 and H 127. The separationQov contacts H 119 disconnects the generator separately excited eld windings from the generator armature. The purpose'o'- this arrangement will be explained later.l Contacts H 122 are in the circuit' for the field control switch actuating coil L 128. The purpose of this arrangement-also will be exlained later. The separation of contacts l 123 disconnects resistance 33,rom across the brake release coil 30. Resistance 33 being of low ohmic value, its disconnection before contacts H 124 engage prevents' excess power consumption from mains 45 and 46. The engagement of contacts H 127 establishes a circuit for the door control motor maintaining relay actuating oil K 130. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of i J 82, by way of line 131 through up levelling direction switch contacts LB 132, down levelling direction switch contacts LC 133, con- 'tacts H 127 and coil K 130. line 85, to the right-hand blade of switch 47 as previously traced. The enga ement of contacts H further prepares t e circuits for the actuating coils of the accelerating switches. The engagement of contacts H 126 short-circuits section 54 of the elevator motor field resistance 29, permitting the motor field to build up to its full strength. The engagement of contacts H 124 completes the circuit for the ne 83 through. coil" 47 by wa of line 55 through contacts A 60,

by way o line 134 through contacts 135 operated by the brake, brake release coil 30 and contacts-H 124, by way of line 58 through contacts A 61, to the right-hand blade of switch 47.

The door control motor maintaining relay coil K in the circuit above traced is subject to the potential drop across resistance 84. The system is arranged so that the voltage thus applied to coil K 130 is sufficient to effect the operation of the relay. Contacts K 136 engage, upon the operation of the relay, to by-pass contacts H 127. The purpose of this arrangement will be seen from later description.

The brake release coil 30 being energized,

the elevator motor field being connected directly to the mains 45 and 46 and current being supplied from the generator armature 15 to the elevator motor armature 21, due to the energization of the generator major and minor separately excited field windings, the elevator motor starts. The minor separately excited field winding as now connected assists the major separatelyexcited field Winding.

As therbrake releases, the brake switch contacts separate to insert cooling resistance 137 in series with ,the brake release coil. These brakeswit-ch contacts are preferably arranged to be separated at the end of the releasing operation. i Separation of contacts 135 also breaks the short circuit around coil O 188, permitting the operation of the accelerating relay This relay operates to cause the'engagement of contacts O 140, completing the circuit for the first accelerating switch actuating coil D 141. The purpose of this arrangement is to utilize the,time con- .,stant of the brake for timing the acceleration 'of the motor, more specifically, for timin the operation of the first accelerating switch. Although the brake release coil is energized 4at the same-time that power is supplied to fand. lever arms represent considerable mass to beset in motion. The circuit for coil D 141 completed 'by contacts O 140 may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, by way of line 107 through the door contacts 51, gate contacts 52 yand contacts N 108, by way of line 142 through contacts H 125, contacts O and coil D 141, contacts l(i5-and 64 of the car switch, to the right-hand blade of switch 47 as previously traced.

The operation of the first accelerating switch, i'n response to the energization of its actuating coil, causes the en agement of contacts D 143, D 144, D 145 an D 146. The engagement of contacts D 143 completes the circuit for the levellin switch motor y41. This circuit may be trace from the left-hand blade of switch 47 by way of line 55 through contacts A 60, by way of line 147 through contacts D 143` field winding 40 and armature 38 of motor 41, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. The levelling switch motor acts, upon energization, to move the levelling switch operating rollers so as to clear the levelling cams during movement of the car; This operation will be explained later. The engagement-of contacts D 144 completes the circuit for holding coils B 115 and H 116. This circuit may be traced from the left-hand blade of switch 47 by way of line 55 through contacts A 60, byway of line 148 through coil H 116 and contacts D 144, by way of line 150 through coil B 115 and contacts B 113, line 151, line 85,to the right-hand blade of switch 47 as previously traced. The purpose ofthe energization of these holding coils will be seen from later description. The enga ement of contacts D 146 completes the circult orthesecond accelerating switch actuating coil E 152. This circuit may be traced from the left-hand blade of switch 47, by way of line r55 through contacts A 60, by way of line 107 through door contacts 51, gate contacts 52 and contacts N 108, by way of 4line 142 through contacts H 125, by way of line 153 through contacts D 146, reactance X 154 and coil E 152,

car switch contacts

66 ,and 64, to the right-hand blade of switch 47 as previously traced. The engagement of contacts D 145 short-circuits section 155 of resistance 27, increasing the voltage applied to the

generator field windings

17 and 18. Thus the generator E. M. F. is increased, increasing the speed of the motor.

The second accelerating switch E does not operate immediately the circuit for its actuatlng coil is completed, its action being delayed by the effect of reactance X 154. Upon operation, contacts E 156 and E 57 separateand contacts E 157 and E 158 engage. The separation of contacts E 156 removes the shunt circuit around a portion of resistance 160. The separation of contacts E 156 before contacts 'E 158 engage prevents excess power consumption from mains and 46. The engagement of contacts E 158 completes the circuit for the first accelerating switch holding coil D 161 andthe maintaining relay actuating coil M 162. This circuit may be traced from the left-hand blade of switch 47, by 4way of line through contacts A 60,l by way of line 151 through contacts E 158, reactance X 163' coil D 161 and coil M 162, line 85, to the righthand blade of switch 47 as previously traced. The maintaining relay contacts M 164 are thus caused to by-pass contacts D 144. The purpose of this arrangement will be described later. The engagement of contacts E 157 short-circuits section 165 of resistance'27 to increase the voltage a plied to the enerator separately excited fie d windingsv 1 and 18. The E. M. F. of the generator, therefore, increases to its full value and the speed of the elevator motor increases. The separation of contacts E 57 removes the short circuit for section 167 of resistance 29 in the elevator motor field winding circuit, bringing the elevator motor up to full speed.

The starting of the car in the down direction is accom lished in a similar manner and will be only griefly described. The operator first moves the car switch into `osition to cause the closure ofthe gate an then into full on position where its contact segment 72

bridges contacts

67, 68, v69, 70 and 71. Thus the circuit-, is completed for the down maindirection switch actuating coil C 168. This circuit may be traced from the left-hand blade of switch 47, through coil H 101 as reviously traced, by way of line 170 throug coil C 168 ,

car switch contacts

68 and 69, b way of line 171 through contacts B 110, hne 85, to the right-hand blade of switch 47 as previously traced. The circuit for coil N 98 is by way of line 172. The circuit for coil D 141 is by way of line 173. The circuit for coil E 152 is by way of line 174. The down main direction switch, upon operation, causes the separation of contacts C 106 and the engagement of contacts C 175, C 176 and C 177, these contacts corresponding with up main direction switch contacts B 110, B 111, B 112 and By 113 respectively. The holding coil of the down main direction switch is designated C 178. Further than this, the operation of starting the car in the down direction is the same as described for starting it in the up direction.

Assume that the car is running in the up direction and that the operator centers the car switch between the second and third fioors in order to stop at the third floor landing. Thus the contact segment 72 moves off

contacts

66, 65, 64 and 63 and the circuits for the second accelerating switch actuating coil E 152, rstA accelerating switchv actuating coil D 141, main brake and field switch actuating coil H 101, up main direction switch actuating coil B 102, levelling control relay coil R 240 and sequence relay coils N 98 and N 100 are broken. The levelling control relay and the second acceleratingswitch drop out im`l mediately. The first .accelerating switch, main brake andv field switch and up main d1.- rection switch are maintained operated,

however, by holding coils D 161, H 116- door and and B 115 respectively. The deenergization of coils N 98 and N 100 is in preparation for the next starting operation. It is to be noted that switch 78 is o ened by the centering of the car switch. he circuit for coil J 82, however, is maintained through concts H 127 and K 136 in parallel and coil The levelling control relay, upon dropping out, causes the reengagement of contacts 241. As previously stated, the purpose of this rela will be explained later.

T Ae second accelerating switch, upon dropping out, causes the separation Aof contacts E 157 and E 158 and the reengagement of contacts E 57 and E 156.` The separation of contacts E 157 reinserts section 165 of resistance 27 in series with the generator separatel excited field windin sto decrease the E.M. .of the generator. T e engagement of contacts E 57 short-circuits section 167 of resistance 29, increasing the strength of the elevator motor field for the stoppin operation. With the generator E. M. F. owered and the strength of the elevator motor field increased, the speed of the elevator motor 1s decreased. The se aration of contacts E 158 breaks the circuit or holding coil D 161 and coil M 162. The first accelerating switch and maintaining relay M do not drop out immediately, however, their action bein delayed by the effect of reactance X 163 1n series with the coils and the discharge resist-y ance 160 in parallel with the reactance and the coils. The engagement of contacts E 156 to short-circuit a portion of resistance 160 isl effective to prolong the time element of the switch and relay. The time element may be adjusted to the desired value by changing the amount of the resistance portion shortcircuited. Relay M is preferably adjusted 'to hold in at a smaller current value than the accelerating switch D. This may be readily accomplished due to the fact that the relay is much smaller and therefore lighter in construction than the accelerating switch and requires less current to hold in.

The first accelerating switch, upon dropping out, causes the separation of contacts D 143, D 144, D 145Aand D 146. The separation of contacts D 144 is in preparation for the next starting operation, contacts M 164 remaining in engagement to maintain holding coils H 116 and B 115 energized. The separation of contacts D 146 also is in preparation for 1the next starting operation, the circuit for coil E 152 having been broken by the movement of the car switch as above described. `The separation of contacts D 145 removes the short circuit for section 155 of resistance 27, decreasin the strength of the generator field. Thus t e generator E. M. F. 1s again decreased and the speed of the elevator motor is reduced.

The separation of contacts D 143 deenergizes the levelling switch motor 41. In this manner the operating rollers of the levelling switch are extended for engagement by the levelling cams. Referring riefly to Figure 2, the levelling switch'motor is operatively connected to the levelling switch by means of an arm 180 on the motor shaft, a connecting link 181 and a lever 182. 1n the starting opfor each floor. The levelling switch is pivfoted on a bracket 187 secured to the car frame. In the stop ing operation, upon the deenergization o the levelling switch motor, a spring (not shown) moves the lever 182 and therefore the levelling switch back into the irst described position with the rollers 183 and 184 extended for engagement by the levelling cams. Each pair of levelling

switch contacts

34, 35, 36 and 37 comprises a stationary contact and a movable contact operated by the engagement of its corresponding roller andlevelling cam. The fast speed contacts 36 and 37 are arranged to separate before their corresponding slow speed contacts 34 and 35 in the levelling operation. Springs (not shown) are provided for causing the separation of the contacts of the pairs as the levelling operation is effected and stops are provided for determining the extent of movement of the rollers as they ride off the levellinIg cams.

t will be assumed that the car has not reached the landing and that the up levelling switch operating roller 183 moves onto the vertical surface of up levelling cam 185 before relay M drops out. The engagement of levelling switch up slow speed contacts 34 completes a circuit for the up levelling direction switch actuating coil LB 188 and the levelling brake and field switch actuating coil LH 190. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, line 191, levelling switch contacts 34, by wlaly of line 192 through coil LB 188 and coil L 190, by way of line 85 through levelling control relay contacts lt 241, to the right-hand blade of switch 47 as previously traced. The engagement of the levelling switch u fast speed contacts 36 completes the circuit for fast speed levelling relay actuating coil LF 193. This circuit may be traced from the left-hand blade of switch 47, by Way of line 55 through contacts A 60, line 191, levelling switch contacts 34, line 194, levelling switch contacts 36, by way of line through coil LF 193 and contacts R 241, to the right-hand blade of switch 47 as previously traced. It is to be noted that, due to the fact that the circuit for coil LF 193 is through levelling switch slow speed contacts 34, the circuit for coils LB 188 and LH 190 must be made in order that the circuit for coil LF 193 may be completed.

The up levelling direction switch LB, upon 132 and the enga-vement of contacts LB 195, LB 196 and cLB 197. Contacts y LB 132 will be referred to later. The engagement of contacts LB'195 and LB 196 prepares circuits for the enerator separately excited field windings for the levelling period. The-engagement of contacts LB 197 completes the circuit for u series field rela actuating coil G 198 and up ard brake switcli actuating coil P 200. This circuit ma be traced from the left-hand blade of switc 47, by way of line 55 through contacts A 60, by

wa of line 201 through contacts LB 197,

coi G 198Y` coil/P 200, and portion 202 of reyactance X 203, line 204, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. v

The levelling brake and field switch, operating simultaneously with the up levelling direction switch, causes the separation of contacts LH 205, LH 206 and LH 212 and the engagement of contacts LH 207, LH 208 and LH 210. Contacts LH 205 are in the circuit for resistance 33 across the brake release coil. Contacts LH 206 are in series with contacts H 119 in the circuit for connecting the generator separately excited field windings to the enerator armature. Contacts LH 212 brea the shunt circuit,'comprising resistance 160, for coils D 161 and M 162. Contac'ts LH 207 bypass contacts H 124 in the circuit for the brake release coil.V Contacts LH 208 by-pass contacts H 126 in the circuit i for section 54 of the motor field resistance 29.

Contacts LH 210 are in the circuit for the field control switch actuating coil L 128. The

engagement of contacts LH 210 is without effeet at this time as contacts H 122 are separated. The purpose of contacts LH 205, LH 206, LH 207, LH 208 and LH 210 will be seen as the description proceeds.

The fast speed levelling rela upon operation, causes the engagement o contacts LF 213 and LF 214. The engagement of contacts LF 213 short-circuits resistance 28 employed to control the strength of the generator field VVcontrol? motor maintaining relay coil K 130,l

Gf tactsLB 132.

during levelling. The engagement of contacts LF 214 by-passes contacts LB 132, LC 133, H 127 and K 136, coil K 130 and switch 78 through resistance 84 in a circuit l forl coil J 82 of the door control motor switch. Since the engagementl of contacts LF 214 generally occurs substantially simultaneously with the sepa-ration of contacts LB 132, the switch J does not drop out. Even if switch J should dropout, the immediate reenergizai tion of coil J 82 upon the engagement of contacts LF 214 wou d prevent the operation ot' the ate and door operating mechanism due to te time required for the mechanism to start in operation. The circuit for the door however, is broken by theseparation of con- `The separation of contacts LH 212 to break aration of contacts B 111, B 112 and B 113 i and the engagement of contacts B L10. The separation of contacts B 113 and the enga ement of contacts B 110 is in preparation or d the next starting operation. The separation of contacts B 111 and B 112 breaks the circuit for the generator separately excited field windings. However, the windings are substantially immediately reconnected to the mains for the levelling operation by the op.

eration of switch L as will be set forth below. The switch H, upon dropping out, causes the separation of contacts H 124, Hy 125, H 126 and H 127 and the engagement of contacts H 119, 'H 122 andH 123. The separation of contacts H125 ,and H 127 is in preparation for the next starting operation. The separation of contacts H 124 and H 126 is Without effect, the circuit for the brake release coil being maintained by contacts LH 207 and section 54 of resistance 29 remaining short-circuited by contacts LH 208. The engagement of contacts H 119 and H 123 also is Without effect as the circuit for reconnecting the generator separately excited field windings to the generator armature is maintained broken by contacts LH 206 and the shunt circuit for the brake release coil 30 comprising resistance 33 is maintained broken by contacts LH 205. The engagement of contacts H 122, however, completes the circuit for the field control switch ractuat-ing coil L 128. This circuit may be traced from the left-hand blade of'switch 47, by way of line through contacts A 60, by way of line 215 through contacts H 122, contacts LH 210 andfcoil L 128, line 85, to the right-hand blade L 216 and L 217 reverses vthe connections for d the generator minor separately excited field winding 18, the engagement of contacts L 216 and L 217 also reconnecting both generator separately excited field windings to the mains. The circuit for the generator field windings may now be traced from the lefthand bladeof switch 47, by way of.l line 55 through contacts A 60, contacts LF 213 short-circuiting resistance 28, contacts yLB 195, by way of line;y 120 through contacts L 217, minor field winding 18, by way of line '218 through contacts L 216, major fild tion, causes the separation of contacts winding 17, line 219, line 220, by way of li'ne 58 through contacts LB 196 and contacts A 61, to the right-hand blade of switch 47. It is to be noted that the circuit for the genera- 'tor field windings through resistance 27 is now also broken at contacts L 118. The polarity of these connections is such 'that the magnetizing force exerted by the maj or field winding is in the same direction as before. As regards the minor field winding, however, current now flows therein in such direction as to create a magnetizing force which opposes the magnetizing force due to the major field winding.

Discharge resistances

24 and 25 act to smooth out not only the changes in enerator E. M. F. due to the reinsertion o resistance 27 in circuit with the separately excited field windin s 17 and 18 in steps,but also the change ue to the disconnection and reconnection o the field windings to the mains. It is to be understood that resistance 27 may be controlled in any number of steps, two being shown merely for convenience of descri tion. v

- ith contacts L 118 and L 121. separated and contacts L 216, L 217, LB A195, LB 196 and LF 213 in engagement, an E. `M. F. is generated which causes the elevator motor to run at a suitable fast levelling speed, as will be seen from later description.

Relay G and switch P do ynot operate irnmediately their actuating coils are energized, their action being delayed by reactance X 203. Switch P, however, is adjusted to operate almost immediately and, upon peradisconnecting resistance 32 from across the brake release coil 30. Relay G, upon operation, causes the engagement of contacts G r 222, completing the circuit for the series eld switch actuatin coil F 223. This circuit ma be traced rom the left-hand blade of switch 47, by way7 of line 55 through contacts A 60, by way of line 224 through contacts G 222 and coil F 223, by way of line 58 through contacts A 61, to the right-hand blade of switch 47. Switch F, upon operation, causes the separation of contacts F 225,

breaking the circuit including resistance 23' in shunt to the generator series field winding 16. The generator series field is so wound that, without the parallel resistance 23, it would have too great an effect for proper operation of the car. The desired compounding is obtained by employing the low resist- Vance shunt. Upon separation of Ycontacts lF 225, the stren h of the series field is increased for the evelling operation so as to aid in bringing the motor to a stop. The short delay in the action of relay G, and therefore switch F, upon the initiation of the levelling operation, is desirable in order that the current in the generator armature-elevator-motor armature circuit may adjust itself Vstrength during the level toA such a value that proper series field ing operation may be obtained.

As the car nears the'third floor landing, roller 183 rides ofi the vertical surface onto the oblique surface of cam 185. This results in theseparation of levelling switch up fast speed contacts 36, deenergizingfast speed levelling relay coil LF 193. elay LF, upon dro ping out, causes the se aration of contacts L 213 and LF 214. T e separation of contacts LF 213 removes the short circuit around resistance 28. The generator' 'the motor 44, thus effecting the automatic gate and door opening operation. The gate and door operating mechanism functions in the same manner as described for opening the gate and door in response to centering the car switch. In this manner the automatic gate and door opening operation is timed so that the gate and door open .as the car stops at the landing. It is to be noted, however, that the automatic gate and door opening operation cannot take place until the levellin switch fast speed contacts separate.

hortly before the car reaches the exact level with the landing, the roller 183 rides off the oblique surface of cam 185, ,thereby separating the levelling switch up slow speed contacts 34. The circuit for coils LB 188 andLH190 is thus broken. Switch LHdro s out, causing the separation of contacts L 207, LH 208 and LH 210 and the reen agement of contacts LH 205, LH 206 an LH 212. The engagement of contacts LH 212 is in preparation for the next startin o eration. The separation of contacts 207 .breaks the circuit for the brake release coil 30 effecting the a plication of the brake. The separation'o contacts LH 207 also breaks the circuit for accelerating relay coil O 138. The accelerating relay O drops out, separating contacts O 140 in preparation for the next startin operation. The separation of contacts L 208 reinserts section 54. of resistance 29 in series with the elevator motor field winding, reducing the current therein to a standin field value. The separation of contacts H210 breaks the circuit for the field control switch coil L 128, the switch dropping out in preparation for the next starting operation. It is to be noted that the separation of contacts L 216 and L 217 and the engagement of contacts L 118 and L 121 reconnects the generator separately

excited field windings

17 and 18 for cumulative action. The reengagement of contacts LH 206 along with the engagement-of contacts L 216 and L 217 reconnects the genping out simultaneouslv with switch LH,.

causes the separation of contacts LB 195, LB 196 and LB 197 and the engagement of contacts LB 132. The engagement of contacts LB 132 is in preparation for the next starting operation. The separation of contacts LB 195 and LB 196 disconnects the generator separately excited field windings rom the mains, the windings being simultaneously reconnected to the generator armature by contacts LH 206, L 216 and L 217 as set forth above. The separation of contacts LB 197 breaks the circuit for coils G 198 and P 200. The relay G drops out immediately, but the dropping out of switch P is delayed slightly due to the effect of the reactance X 203 and discharge resistancel 226. It isto be noted that the discharge current for up coil P 200 and the reactance passes through down coil P 227 in such direction as to cause coil P 227 to assist coil P 200 in maintaining switch P in operated condition. Relay G, upon dropping out,

- causes the separation of contacts G 222 to deenergize coil F 223, switch F dropping out in turn to cause the engagement of contacts F 225. The engagementl of contacts F 225 reconnects resistance 23 in parallel with the landing.

generator series field winding 16. Switch P, upon dropping out. causes the engagement .of contacts P 221.

Thus the brake being applied and the generator separately excited field windings being disconnected from the mains, the car is brought to rest level with the third floor Since the engagement of contacts P 221 is delayed, the brake release coil 30 discharges only into resistance 31 of relatively high ohmic value and a hard application of the brake is obtained. In this manner a positive stop at the landing is assured.

lVith the sequence of operations as above described the car will be slowed down and stopped level with the desired landing without sacrifice of smoothness. However, should the car switch be centered with the car at a greater distance from the landing, the maintaining relay would hold in to effect, through its contacts M 164, the retention of the main direction switch and main brake and field switch in operated condition. Should relay M drop out before the levelling switch contacts engage, the subsequent engagement of the levelling switch contacts as the levelling switch roller rides onto the cam would cause the operation of switches LB and LH and relay LF to bring the car to a level with the floor. In the event that the car switch is centered late in the stopping operation, as for example when the levelling switch operating roller strikes, the .levelling cam upon the dropping out of the first accelerating switch D, the immediate separation of contacts LH 212 forces the dropping out of the main direction switch and the main brake and field switch to permit the immediate change of the connections for the field windings and thus slow down the elevator motor more rapidly. In this manner the tendency for the car to overrun the floor is reduced.

Should an overrun occur, however, the system is yarranged so that the operation of the switches is modified. Assuming in the above example that the car overruns the third floor landin to the extent of causing the engagement o levelling switch down slow speed contacts 35, a circuit is completed for down levelling direction switch actuating coil LC 228 and coil LH 190. This circuit may be traced from the left-hand blade of switch 47, by way of line 55 through contacts A 60, line 191, contacts 35, by way of line 23()I through coil LC 228, by way of line 192 through coil LH 190, line 85, to the right-hand blade of switch 47 as previously traced. Contacts LH 205,

LH 206 and LH 212 are separated and con? tacts LH 207, LH 208 and LH 210 are engaged sothat the circuit for resistance 33 across the brake release coil is broken, the brake release coil is energized, resistance section 54 for the elevator' motor field winding is short-circuited and the field control switch actuating coil L 128 is energized. Contacts LH 212 insure the dropping out of the main direction switch. lVith coil L 128 energized contacts L 118 and L 121 are separated and contacts L 216 and L 217 are in engagement. The switch LC operates to cause theseparation of contacts LC 133 and the engagement of contacts LC 231, LC 232 and LC 233. The separation of contacts LC 133 is without particular effect at this time. With contacts LH 206, L 118 and L 121 separated and contacts LC 231, LC 232, L 216 and L 217 in engagement, the major and minor separately excited field windings are disconnected from the generator armature and are connected to the mains in such manner as to cause their magnetizing forces to oppose'each other. Due to resistance 28 not being short-circuited, the desired voltage is applied to the generator separately excited field windings for slow speed levelling operal tion. Since the circuit for the generator separately excited field windings is through the down levelling direction switch contacts, the flow of current through the windings is in a reversed direction from that during the levelling operation upon the car approaching the floor in the up direction and the car is caused to start in the down direction.

The engagement of contacts LC 233 combrake switch actuating coil P 227. This circuit may be traced from the left-hand blade 'of switch 47, by way of line 55 through contacts A 60, by way of line 235 through contacts LC 233, coil G 234, coil P 227 and portion 236 of reactance X 203, line 204', by way of line 58 through contacts A 61, to the righthand blade of switch 47. Relay G and switch P do not operate immediately upon the engagement of contacts LC 233. When approaching the floor in the up direction as described, the current flowing through reactance portion 202 caused a flux to be built up in the reactance X 203 in one direction. Upon the separation of contacts LB 197, the current in the reactance and coil P 200 discharged into resistance 226 tending to maintain the iiux built up and, as previously explained, switch P in operated condition. Upon the engagement of contacts LC 233 on the overrun, the current supplied to coils G 234 and P 227 must reverse the iiux in the reactance, thus taking a longer time to build u to a value sufficient to cause the operation o relay G and switch P. Thus contacts F 225, depending for their operation upon the operation of relay G, remain closed temporarily to insure that the current in the generator armaturemotor armature circuit has fallen to a low value. Since the current in the series' field winding may be flowing in a direction such as to cause the generation of an E. M. F. which is of proper polarity for operating the car in the down direction, immediate increase in the strength of the series field might result in an overrun in the down direction. As the car returns to the floor, it is stopped by the separation of the levelling switch slow speed contacts 35 in 'a manner similar to that described for approaching the ioor in the up direction.

If the overrun is great enough to cause the engagement of the levelling switch down fast speed contacts 37 as well as the levelling switch down slow speed contacts 35, coil LF 193 is energized. As before,-relay LF causes 'the engagement of contacts LF 213 to shortcircuit resistance 23, increasing the generator voltage and causing the elevator motor to run at its fast levelling speed. Relay LF also causes the engagement of contacts LF 214 to energize coil d 32 again in the event that it has become deenergized. Upon such an overrun, the automatic gate and door opening operation does not occur until contacts LF 214 separate, as previously described. Further than this, the operation on an overrun is as above described.-

1t is to be understood that the operator may control both the acceleration and retardation of the car by moving the car switch in steps. Tn the event that the operator starts the car from a fioor by moving the car switch only so far as to engage one of the feed contacts, for example contact 64, the up main direction switch B and main brake and field switch are operated to com lete the circuit for the generator field win ing, by the engagement'of contacts B 111 and contacts B 112, and to cause the release of the brake, by the engagement of contacts H 124. As the actuating coil of the first accelerating switch D is not energized, this switch does not operate and the levelling switch motor is not encrgized to4 move the levelling switch rollers to clear the cams. The levelling control relay R, however, operating along with switches B and H, causes the separation of contacts R 241 and thus prevents the energization of the down levelling switch actuating coil LC 228 as a result of the operation of the levelling switch during the upward movement of the car away from the licor. Contacts LCv 231 and LC 232, therefore, do not engage, preventing the establishing of a shunt circuit around the generator separately excited field winding. Should the operator suddenly move the car switch from one position into the other, for example from up into down position, injury to the system is prevented by contacts B 110 which remain separated until the up direction switch drops out. It is to be noted that, when the car is suddenly reversed or stopped between floors or stopped by opening the safety switch 50, the switch P is not operated. Thus contacts P 221 are in engagement and a soft application of the brake is obtained.

'The conditions under which levelling operations have to take place are subject tovconstant Variation. This is true even with a given load in the car. These conditions depend upon the position of the car in the levelling zone at the time that the levelling operation begins. Thus the car may have to be accelerated or retarded and it may have t0 move upor down. Consistent results can be obtained under such conditions by having the generator field build up quickly to the desired strengths. This may be accomplished by making the time constant of the separately excited generator field windings asy small as possible and by causing the mutual induction between the series and separately excited field windings to be as little as posseries as are those forming the minor field4 winding. The coils are so wound as to provide poles of alternate polarity. With the switc L in deenergized position, as during car switch operation, the current flows through the coils on each pole in such direction as to have the minor field winding assist as previously described to separate contacts L 118 and L 121 and to effect the engagement of contacts L 216 and L 217. As a result, the

direction of the flow of current through the` major field winding is unchanged but the flow of current through the minor field winding is reversed. The field flux is now produced by of the large and small coils. This difference may be made such, by selection ot the number of turns in the coils, that the desired E. M. F. for causing the elevator motor to run at the desired fast levelling speed is generated with the full voltage of the mains applied to the windings. The desired slow levelling speed is obtained by means of the resistance 28, (see Figure 1).

In a generator provided with the usual series field winding and separately excited field winding, the series field winding, due to the effect of the mutual inductance upon the separately excited field winding, retards v the building up of the generator field. In

some instances, especially under such conditions as are'obtained during levelling, the series winding, on account of mutual inductance, may cause the temporary reversal of the flux due to the separately excited winding. Thus, not only 1s the operation of the system rendereduncertain but the time required for the separately excited winding to overcome the effect of the mutual inductance adds to the time usually required to build the generator field up to its desired strength. With the separately excited windings arranged as illustratedon the drawings, the l effect ofthe opposing turns of the two coils' on each field pole during levelling is that the coeficientof self inductance'of the two coils and the coeflicient of mutual inductance of the two coils with the corresponding series field coil are the same as if each pole were wound with a number of turns equal to the difference between the number of turns of the two coils. Thus the inductance is reduced, so that the generator field will establish itself quickly during levelling operation. i

This arrangement for the control of the separately excited field windings minimizes the possibility of the elevator car moving at an excessive speed during the levelling period. The automatic opening of the'gate and door during this period renders the feature of particular importance. In systems employing resistance in series with the elevator motor armature to control the speed of the the difference of the ampere turns motor duringlevelling, or where the voltage g applied to the armature of the elevator motor during levelling is controlled by means of resistance in series with the separately excited field winding of the generator which supplies power to the motor, there is always the possibility of all or a portion of such resistances becoming shortcircuited or grounded, causing the speed of the elevator motor to increase. If mechanism were employed, as in 'the present system, to eect the automatic opening of t e gate and door during the levelling period, the sudden increase in speed might occur while the gate and door were being opened, or'after the gate and door were open when the levelling arrangement is slow in bringing the car to a level with thelanding. In the present system, the circuit for resistance 27 is broken by the contacts on the main direction switches and field control switch contacts L 118. With such an arrangement, it is impossible for the accidental short-circuiting or grounding of resistance 27 during levelling and gate and door opening operation to cause an increase in the speed of the elevator car. An accidental short circuit of resistance 28 can do no more than cause the car to run atv its fast levelling speed. It is to be understood that contacts could be provided on the field control switch L to break the circuit for the gate motor maintaining relay coil K 130, instead of employing contacts LB 132 and LC 133, inorder to insure that the gate and door would not open unless the connections for the field windings were changed.

Referring to Figure 3. only that portion of the control diagram which differs from the diagram of Figure 1 has been illustrated. In this diagram the levelling directionswitch contacts LB 195, LB 196, LC 231 and LC 232 are arranged for by-passing main direction switch contacts B 111,13 112. C 175 and C 176 respectively. Resistance 28 is omitted and resistance 27 is employed to control the strength of the generatonfield both during car switch and levelling operations. Additional contacts L 240 are varranged on the field control 4switch and contacts LH 241 on the levelling brake and field switch. Contacts LH 241 are arranged for short-circuiting an adiustable portion of resistance 27. Contacts LF 213, employed in Figure 1 to short-circuit resistance 28, are arranged to short-circuit the remainder of resistancey 27 Contacts L 240 are employed to prevent the completion of these short circuits until the main direction switch-and main brake and field switch drop out. It is believed that the operation of the system as thus arranged will be obvious from the description of the operation of the systemof Figure 1. With such an arrangement, the accidental short-circuiting dr door are opening can have no greater effect than to cause the elevator motor to run at its fast levelling speed.

As many changes could be made in the 5 above arrangements and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or 1o shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: 1. In combination. a direct current motor, a variable voltage direct current generator for supplying current to said motor, said generator having a plurality of field windings, one of said windings` having a smaller num-l ber of turns than the other, a source 'of direct current, means for causing the motor to run at a certain speed, said means comprising means for connecting said windingsl in series Arelation to said source in such manner as to cause their cumulative action, and means for causing the motor to run at a slower speed, said last included means comprising means for reversing the low of current through one of said windin 2. In combination, a direct current motor, a variable voltage direct current generator for supplying current to said motor, said generator having a. plurality of iield windings, each of'which comprises a plurality of series connected field coils, one for each field pole, a source of direct current, means for causing the starting` of the motor, said means comprising means for connecting said windings in series relation and applying a low voltage from said source to said windings so con- 40 nected, means for bringing the motor up to a certain speed, said second named means comprising means for increasing the voltage applied to said windings, and means for reducing the speed of said motor below said certain speed, said last named means comprising means for reversing the connections of one of said windings and for applying said increased voltage to said windings.

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

FREDERICK HYMANS.