US1783629A - Push-button elevator-control system - Google Patents

Description

Dec. 2, 1930. E. w. SEEGER 1,783,629

PUSH BUTTON ELEVATOR CONTROL SYSTEM Filed Oct. 27, 1926 2 Sheets-Sheet l 6d, w NVENTOR Mt (34/10 BY I A TTORNEYS.

Dec. 2, 1930, E. w. SEEGER PUSH BUTTON ELEVATOR CONTROL SYSTEM Filed Oct. 27, 1926 2 Sheets-Sheet 2 W a l w K mm 1 av mam W3 \K PatentedDec. 2, 1930 'U rrEo srA'ras' PATENT orrlca EDWIN W. SEEGEE; OF SOUTH MILWAUKEE, 'WISCONSIN, ASSIGNOR,- BY MESNE AB- SIGNHEHTS, 'I'O CUTLER-BAUER INS TIGH OF DELAWARE OI MILWAUKEE, WISCONSIN, ACORZPOBA- PUSH-BUTTON ELEVATOIR CON'IROL SYSTEM I Application filed october 27, 1926. Serial at. 144,415.

This invention relates to push button elevator control systems.

An'object' of the invention is to provide improved and simplified selector mechanism providing foraccurate positioning of the car in stopping at any desired preselected land- Another object is to provide selector mechanismofthe above character adapted to control the speed of the driving motor during automatic initiation of the stopping operationof the latter.

Another and more specific object of the invention is to provide improved selector mechanism adapted to insure slow speed operation of the driving motor at a predetermined point in the travel of the car, together with cooperating means in the hoistway and on the car for effecting accurately positioned 2 stopping of the-latter at a preselected landin 1 I iiinother object is to minimize the number of car operated switches required and to avoid the noise and wear incident to unnecessar operation of the latter.

nother object is to provide selector mechanism operable in a direction and to a degree,

correspondin with the movement of the car, with means or automatically adjusting the 3 selector at the upper and lower limits of travel of the car, 1 necessary 1 Another object is to generally improve the construction and operation oi control systems of the character aforementioned.

Other objects and advantages of the invention will hereinafter a pear.

i The accompanying rawing illustrates one embodiment of the invention which will now be described it being understood that various changes may be made in the details of cohstruction and operation of the system without departing from the spirit and scope of my invention as defined in the a pended claims.

In the draw in Figure 1 illustrates sche-'- matically and iagrammatically a control system constructed in accordance with my invention;

Fi 2 is an across-the-line diagram of the circuits and circuit connections illustrated in to Fig. ligand high speed connections, and vice versa, under- .Fig. 3 is a diagrammatic view of my improved form of selector drive and adjuster.

Referring first to Fig. 1, M designates a motor adapted to drive the elevator car (not shown) through any suitable or well known connection.- As shown, the direction of operation of motor M is controlled through suitable reversin switches U and D, operation of the latter eing controllable respectively by means of relays UR and DR,subject, however, to control by a retiring limit switch RS. Motor M is provided with a low speed winding (the terminals of which are indicated at T, T and T energization of which is controlled by switch S, and a high speed winding (the terminals of which are indicated at T T? and T energization of which is controlled by switchF; suitable relays SDR and SAR being provided to change from low to given conditions as hereinafter described. Acceleration under low speed conditions is controlled by exclusion of resistances R and R through operation of switch ACS in the manner hereinafter described, resistances R", B and B being adapted for permanentinclusion in circuit with the low speed winflmg. a Y I Relay SDR is in turn subjected to control by relay FAR, the latter being also adapted totherea'fter eif ect operation of accelerating switches ACF andACF" in sequence, to ex- 4 clude resistances R, R and R, R, respectively, from the circuit of the high speed winding.

A brake releasing coil BR and the winding of a non-interference relay for control of the various-push buttons are arranged to be connected across lines L L upon closure of switch U or switch D;

l have illustrated my invention as applied w to control of an elevator having four floors or landings, but it is to be understood that the same is likewise applicable to control of elevators having a greater or lesser number of landings. Thus I have provided landing relays LR, LR, LE and LR, corresponding to the first to fourth landings, respectively.

Initialenergizaticn of the respective relays ion is controlled by push button switches LP,

' LP LP" and LP located at the Several landings, or'by corresponding push-buttons GP,

closureiof all of the landing oor switches LD, LD, LD and LD, as will be obvious. Certain of theaforementioned relays and switches are provided with normally open or normallyclosed auxiliary contacts, or both, which function in the manner hereinafter set forth.

Operation of the control system will now be described with more particular reference to the across-the-line diagram 'of Fig. 2. T bus with the car at the second landing,- as indicated in the drawing by the position of selector switch LS, and assuming that it is desired to call the car to the fourth landing, the push button LP at the fourth landing may be depressed, thereb completing a common energizing circuit or the windings of relays LR and UR, respectively. Said circuit may be traced from line L through contacts 10 of overtravel limit switch OT and contacts 11 of overtravel limit switch OT, thence by conductors 7 5, 76 and 31 through normally closed auxiliary contacts 12 of relay DR and normally closed auxiliary contacts 13 of relay UR and through the normally closed upper contacts of push button switches GP, OP, Cl and GP, thence through the normall closed contacts 14 ofnon-inter'ference re ay NI'R and through the normally open lower cont-acts of push button switch LP, thence through the winding of relay LR to contact 15 of selector switch LS to segment 16 and contact 17 of the latter, through the winding of relay UR 'by conductors 77 and 78 to andthrough the normally closed contacts of the emer ency stop switch located within the-car, t ones through the contacts of car door switch GDS (assuming closure ofthe car door) and the contacts 18 of overtravel limit switch OT, thence through the contacts of the landing door switches Ll), LD", LU andLD, respectively, and through contacts 19 of overtravel limit switch OT to line l As illustrated in Fig. 1 cams HG, HC HQ and HC are provided inthe hoistway ad3acent to the first to fourth" landings, respectively; whereas with the car at the second landing and the winding 20 of retiring switch RS deenergized the contacts 21 of said switch will be separated throu h engagement of roller 22 with cam HO. fiowever, upon closure of relay UR the contacts 23 thereof are adapted to complete an energizing circuit for the winding 20, thus permitting normally closed positioning of contacts 21, said circuit extending from line L thrgugh contacts '10 and '11 as aforedescribed,thence by conductors and 24 through contacts 23, by conductor 25 through winding 20 by conductors 26 and conductors 75 and 76 as aforedescribed,

thence through contacts 28, by conductors 29 and 79 through the winding of switch U, through-the contacts of limit switches TU and CU and the contacts 21 of switch RS,

thence by conductors 80 and 78 through the emergency stop push button switch, and to line L as heretofore traced. Upon closure of switch 11 a maintaining circuit is provided therefor through closure of its auxiliary contacts 30. in shunt with the contacts 28 of relay UR.

Upon energization of the relay LR in the manner aforedescribed a maintaining circuit is provided therefor which is independent of the various push button control switches, said circuit extending from line L through contacts 10 and 11, thence by conductors 75, 76, 31, 32 and 33 through the contacts of said relay LR and through the winding thereof to line L as heretofore traced. Thus upon'closure of relay UR the normally closed auxiliary contacts 13 thereof are opened to disconnect the push button switches from the line, but the energizing circuits of relays LR and UR will be maintained as aforedescribed.

Under the aforedescribed conditions an energizing circuit is provided for the winding of low speed switch S, said circuit extending from line L through contacts 10 and 11, by conductors 75, 24, 52, and 81 through the winding of switch, S, thence by conductor 82 through normally closed auxiliary contacts 36 of relay SDR, or alternatively through normally closed auxiliary contacts 37, 37 and 37 of high speed switch F by conductor 83 to conductor 27, and thence through contacts 18 to line L as heretofore traced.

Thus upon closure of switches U and S as aforedescribed the low speed windings of motor M will be energized through circuits extending from line L by conductors 8 1 and 85 through one set or contacts of switch U thence by conductor 86 through contacts S of switch S and through resistances R and R to terminal T; also from line L by conductors 87 and 88' through contacts S of switch S and through resistances R and R to terminal '1 and from line L by conductors 89 through the other set of contacts of switch U and by conductors 42 and 90 through resist- I through the first-mentioned set of contacts of switch U, by conductors 38 and 39 through said winding and the normally closed contacts 40 of relay SAR, and by conductors 41 and 42 through the other set of contacts of switch U by conductor 89 to line L'. Switch ACS thereupon closes to short-circuit resistances R and R thereby. increasing the speed of the motor.

Also upon closure of relay UR and switch U an energizing circuit is provided for the winding of relay FAR, said circuit extending from line L to conductors 75 and 24, thence through thecontacts 23 of relay UR and by conductor 91 through auxiliary contacts 43 of switch U, through the winding of relay FAR and through normally closed auxiliary contacts 37 37 and '37" to conductors,83 and 27, and thence to line L as previously traced. The pivoted contactor 44 0f relay FAR is thereupon moved upwardly into engagement with contact 45, thereby completing an energizing circuit for the winding of relay SDR, said circuit extending from line L to and through the auxiliary contacts 43 of relay U, thence by conductors '92, 46 and 47 through the winding of relay SDR, by conductors 48 and 49 through contactor 44 and contact 45, and by conductors 93, 26 and 27 to line L as previously traced. Relay SDR in closing provides a maintaining circuit for itself through its contacts 50 shunting con tactor 44 and contact of relay FAR.

Relay SDR in closing also completes an energizing circuit, through its contacts 51, for the winding of switch F; said circuit extending from line L to conductors 75 and 24, thence by conductor 52 through said winding, by conductor 53 through said contacts 51, and thence to conductors 26 and 27 and line L as heretofore traced. Switch F in closing effects opening of its normally closed auxiliary contacts 37, 37, 37 and 37 thereby interrupting the energizing circuit of relay FAR and the alternative energizing circuit of switch S, the other energizing circuit of switch S having been likewise interrupted through opening of normally closed auxiliary contacts 36 of relay SDR. Switch S having been opened and switch F closed in the manner just described, an alternative maintaining circuit is provided for the latter through closure of its normally open auxiliary contacts F and reclosure of the normally closed auxiliary contacts S of switch The main contacts F and F of switch F being thus closed, motor M is connected to the line through its high speed windings. the circuits thereof extending from line L by conductors 84 and 85 through one set of contacts of switch U, thence by conductors 38 and 86 through contacts F through resistances R and R to terminal T: also from line L by conductors 87 and 94 through contacts F and resistances R and R to terminal T and from line L byv conductor 89 through the other set of contacts of switch U and by conductors 42 and 90 to terminal T.

I Relay FAR having been deenergized as aforedescribed, contactor 44 thereof tends to move by gravity to the position illustrated in Figs. 1 and 2 wherein it engages contacts 54 and 55, contact 54 being of greater length than contact 55'whereby said contacts are engaged sequentially. However, relay FAR is provided with a down-dashing dashpot ,56 for retarding the reclosing movement of contactor 44 with respect to contacts 54 and 55. Thus, with contacts 50 of relay SDR closed as aforedescribed, reelosure of contactor 44 and contact 54 provides an energizing circuit for the winding of accelerating switch ACF, which circuit may be traced from line L to conductor 46 as aforedescribed, thence by conductor 57 through said winding, thence through-contact 54 and contactor 44 by conductor 49 through contacts 50 of relay SDR, and thence by conductors 26 and 27 to L as heretofore-traced. The contacts of switch ACF thereupon close to short-circuit resistances R and R Thereafter contactor 44 comes into engagement with contact 55 thus completing an energizing circuit for the winding of switch ACF which circuit may be traced from line L to conductor 46,

through said winding, thence through contact 55 andlcontactor 44 to conductor 49 and contacts 50 of relay SDR, and thence to conductors 26 and 27 to 'line L. The contacts of switch ACF thereupon close to short-circuit resistances R and R, thereby connecting the high speed. winding of motor M directly acrossthe line.

In the manner aforedescribed motor M is started and accelerated to full speed operation thereof. Also during movement of the car from the second landing toward the fourth landing under the aforementioned conditions the landing selector switch LS is moved to a proportional degree.

In Fig. 3 I have diagrammatically illus trated one form of driving connection for the landing selector switch LS. Said connection as shown comprises a relatively small pulley 58 secured to the motor shaft 59 and a relatively large pulley 60 secured to a shaft 61 carrying the selector LS. Pulleys 58 and 60 are so proportioned as to provide the necessary reduction in speed and the same are connected by a belt 62. Thus upon operation of motor M in a direction to effect upward movement of the car, selector LS is driven at a proportional speed in a clockwise direction, as indicated by the arrow, Figs. 1 to 3.

Selector LS as shown must be limited to clockwise and counterclockwise movement respective up and down limits of travel of the car. Said means may comprise a pin or other projection 63 on pulley and a pair of opposed abutments 64 and 65 arranged in the path of said pin. Thus upon movement of the car to the fourth landing selector LS is permitted to move in a clockwise direction to a position wherein segment 16 is disengaged from contact 15, but no farther, due to engagement of pin 63 with abutment 64; any tendency to drive selector LS farther being compensated for by slippa e of belt 62-on pulley 60, thus obviating t e necessity for employment of a slip-clutch in the drive. Similarly upon downward movement of the car toward the first landing, counterclockwise movement of selector LS is permitted until pin 63 engages abutment 65, whereas any tendency to drive the selector farther in such direction is compensated for by slippage of belt 62 on pulley 60 as aforedescribed.

It may be pointed out here that finely calibrated adjustment of selector LS is unnecessary, and hence any slight inaccuracy or misalinement of the selector during oscillation thereof between its respective limits will not affect the operation of the system as a whole.

Thus with motor M brought to full speed in the manner aforedescribed, and after the car has moved upwardly past the third landing, but prior to arrival thereof at the fourth landing, segment 16 of selector LSis adapted to move out of engagement with contact 15, thereby interrupting the common energizing circuit of the windings of relays LR and UR. Upon deenergization of relay UR the contacts 28 thereof will be opened, thus tending to interrupt the energizing circuit of the winding of switch U. The energizing circuit of switch U is maintained, however, throu h closure of its auxiliary contacts 30 as afore escribed. Contacts 23 of relay UR will also be opened, thereby interrupting the energizing circuit of the winding 20 of retiring switch RS. Said switch will thereupon be permitted to oscillate on its pivot 66 to a position wherein the cam HC will be in the path of roller 22, but the contacts 21 of said switch will be maintained closed through the action of spring 67.

Also upon opening of contacts 23 of relay UR the energizing circuits of relays ACF ACF and SDR will be interrupted, as will be obvious. Thereupon resistances R to R will be reincluded in circuit with the high speed windings of motor M, thus reducing the speed of the latter. Moreover, upon deenergization of relay SDR the auxiliary contacts 36 thereof will be reclosed, thereby completing the a't'oredescribed energizing circuit for the winding of low speed switch S. Contacts 51 of relay SDR in opening interrupt one of the maintaining circuits for switch F, the alternative maintaining circuit of said switch being also interrupted immediately upon clolimit switch 0T sure of switch S, through opening of the auxiliary contacts S of the latter.

With switch F thus opened and switch S closed motor M will be brought to low speed, whereas upon arrival of the car at a predetermined point adjacent to the fourth landing roller 22 on the switch RS attached to the car will come into engagement with cam HQ, thereb opening the contacts 21 of said switch to e ect interruption of the energizing circuit of switch U. Upon opening of the contacts of switch U the energizing cir-.

'cuit of brake coil BB is interrupted whereby the brake is released and the motor stopped with the car accurately positioned at said landing.

By employment of a retiring switch of the character herein disclosed I obviate the usual noise incident to operation of one or more switches during movement of the car past the several landings. Moreover, by the arrangement described the amount of wear on the operating parts ofthe selector mechanism is minimize Referring again to Fig. 1, it will be noted that I have provided normally closed limit switches CU and TU which are located at spaced points in the hoistway adjacent to the upper landing but below the up overtravel limit switch OT; whereas similar limit switches CD and TD are located at spaced points in the hoistway adjacent to the lower landing but above the down overtravel Thus as illustrated more clearly in Fig. 2 the car may normally move upwardly to a position wherein limit switch CU is opened without interrupting the energizing circuit of switch U, providedthe reduction in speed of the motor is being accomplished by closure of the low speed switch S, which results in closure of the normall open auxiliary contacts S of the latter. X shunt around the contacts of limit switch CU is thus provided, which may be traced from the contacts of limit switch TU through said auxiliary contacts S, and through the contacts of limit switch CD to and through contacts 21 of retiring switch RS. If the car should effect opening of both limit switches TU and CU prior to closure of low s eed switch S the energizing circuit of switc U will be interrupted immediately to effect stopping of the motor and consequently of the car, as aforedescribed. The operation of limit switches CD and TD during movement of the car to the first landing is in all respects like that of limit switches CU and TU as just described, and hence further descri tion thereof is deemed unnecessary. Tie function of limit switches OT and CT is well understood by those skilled in the art, and further description thereof is deemed unnecessary.

The operation of relay NIH is also well understood, and the same forms no part of the present invention. Similarly the arrangement of the electrical interlocks between the various push button switches per se forms no art of thepresent invention.

It is thoug t that the operation of the con-v trol system in all other respects will be obvious from the foregoing. It may be noted, however, that upon completion of an operation, such as that described in connection with movement of the car from the second landing with accurate stopping thereof at the fourth landing, all parts of the system are automatically reset for further automatic operation upon depression of one of the push button switches. Thus assuming the car to have arrived at the'fourth landing and further assuming that the erson who called the car has opened the lan ing door LD and the car door ODS and has entered the carandreclosed said doors. The car may then be directed to anyof the other landings by temporarily depressing the proper'push button GP, GP or (3P Assuming depression of push button G1 a common energizing circuit will be provided for-relays LR and DR, which circuit extends from line L to and through contacts 10 and 11 of switches OT and OT and by conductors 75, 76 and 31 through auxiliary contacts 12' and 13 of relays DR and UR, through lower contacts of push button switch (3P thence through the winding of relay LE to and through contact 68,segment 69 and contact 70 of selector LS, thence through the winding of relay DR and to line L as previously traced. Thereupon switch D is energized and closed-to initiate operation of motor M as aforedescribed, but in a reserve direction. The accelerating and slowing down operations of motor M are substantially as aforedescribed, and hence more specific description thereof is deemed unnecessary. It may be noted that selector LS is provided with a contact 71 for cooperation with segments 69 or 16, as the case may be, durin calling or directing of the car to the secon landing; whereas said selector LS is likewise provided with a contact 72 for cooperation with segments 69 or 16 during calling or directing of the car to the third land- The normall open " auxiliary contacts 73 and 74 of switc 1 1) correspond with normally open auxiliary contacts 30 and 43 of switch U and function in a like manner.

As aforeindicated, relay FAR is provided those skilled in the art that certain features thereof may be applied with equal facility to the control of a single speed motor.

What I claim as new and desire to secure by Letters Patent is:

1. In a push button elevator control system, the combination with a variable speed vreversible motor for driving the car, of a landing, whereby said motor is stopped only Y when the car is accurately positioned at said landing, said selector switch being also operable to insure low speed circuit connections for said motor prior to arrival of the car at said landing.

2. In a push button elevator control system, the combination with a car, of a variable speed reversible motor for driving the same, a plurality of ush button switches within the car and at tlie respective landings for selectively initiating operation of the motor, means comprising a selector switch for controlling the direction of operation of said motor, a normally closed limit switch carried by the car and cams in the hoistway adjacent to the respective landings tending to eflect opening of said limitswitch, and means controlled by said selector switch for retiring said limitswitch pending approach of the car to a point adjacent to a preselected landing, said selector switch thereupon acting to insure release of said limit switch for engagement of the latter with a cam in the hoistway adjacent to said landing, whereby said motor is stopped only whensaid car is accurateconnections for the motor prior to said stopping thereof.

3. In a push button elevator control system, the combinationwith a car, of a variable speed .driving motor therefor, means includin ,a plurality of push button switches for se ectively initiating operation of said motor for effecting travelof said car to.a preselected point, said means also comprising a selector device operable to insure low speed connections for themotor during approach of the car to said cpoint and prior to stopping of the motor, an cooperating means adjacent to said point and on the car to insure accurately positioned stopping of the latter in the first instance through interruption of said low speed connections.

4. In a' push button elevator control system the combination with a car, of a variable speed reversible motor for driving same, means including a plurality of push button switches for selectively initiating operation of the motor to effect movement of the car toward a preselected point, said means including selector mechanism to control the direction of operation of the motor, said mechanism being also adapted to insure predetermined reduced speed conditions of the motor without interruption of the power supply-thereof at a given point in the travel of the car during approach of the latter to said preselected point, and cooperating means adjacent to said preselected point and on said car for effecting interruption of said power supply to insure accurately positioned stopping of the car at said pre-selected point.

5. In a selector mechanism for push button elevator control systems, the combination with a motor for driving the car, of an element having movement proportional to the movement of the car, means including a plurality of push button switches and said ele ment for prcselecting the landing at which the car is to be stopped, said element acting automatically when the car is approaching and adjacent to said landing to vary the speed of said motor without interrupting the power supply thereof, and means comprising cooperating elements on the car and in the hoist-way to insure accurately positioned stopping of the car at said preselected landmg.

6. In selector mechanism for push button elevator control systems, the combination with a motor for driving the car, of an element having movement proportional to the movement of the car, means including a plurality of push button switches and said element for preselecting the landing at which the car is to be stopped, said element acting automatically during approach of the car to said landing to vary the speed of said motor while maintaining the same direction of power operation of the latter, and means comprising a cam in the hoistway and a cooperating switch on the car to initiate and effect stopping of the motor when the car is accurately positioned at said landing.

7. In an elevator control system, the combination with a car, of a variable speed reversible motor for driving same, a plurality of push button switches operable selectively to effect operation of said motor, means operable in a direction and to a degree corresponding with the movement of said car and cooperating with said push button switches to preselect and control the direction and approximate duration of operation of said motor, means controlled by said last mentioned means and operable automatically during approach of the car to a preselected landing to insure a predetermined reduction in speed of said motor as an initial step in the stopping operation of the latter, and means for initially stopping said motor from low speed with the car accurately positioned at said landing.

8. In an elevator control system, the combination with a car, of a variable speed reversible motor for driving the same, an electromagnetically o erable brake for said motor, a plurality 0 push button switches located within the car and at therespective landings, means cooperating with the respective push ,button switches for initiating operation of said motor and for selectively controlling thewdirection and approximate duration of operation thereof, said means being also operable to automatically accelerate said motor during movement of the car in a given direction toward a preselected landing and for thereafter insuring predetermined low speed circuit connections for said motor prior to arrival of the car at said landing, and means carried by the car and operable upon movement of the latter in said given direction to a predetermined point with respect to said landing to immediately efl'ect interruption of the power connections of said motor and application of said brake to insure accurately positioned stopping of the car at said landing in the first instance.

9. In an elevator control system, the combination with a car, of a variable speed reversible motor for driving the same, a plurality of push button switches located within the car and at the respective landings, means cooperating with the respective push button switches for initiating operation of said motor and for selectively controlling the direction and approximate duration of operation thereof, said means being also operable to automatically accelerate said motor pending movement of the car in a given direction to a point adjacent to a preselected landin and for thereafter insuring predetermined low speed circuit connections for said motor prior to arrival of the car at said landing, and means carried by the car and operable upon movement of the latter in said given direction to a predetermined point with respect to said landing to immediately interrupt operation of said motor to insure accurately positioned stopping of the car at said landing in the first instance.

10. In a push button elevator control system, the combination with a car, of a variable speed motor for driving the same in reverse directions selectively, a plurality of push button switches located within the car and at the respective landings and operable selectively to initiate operation of the motor, means comprising a selector driven by said motor and cooperable with the respective push button switches to preselect the direction and approximate duration of travel of said car, said selector being also operable automatito the respective landings tending to opencally to reduce the speed of said motor while maintaining the power connections thereof during approach of the car to a preselected landing, and a retiring switch carried by said car and controllable by said selector during approach of the car to said landing for automatic movement into a position to engage a cam adjacent to said landing to thereby provide for accurately positioned immediate stopping of the car with respect to said landing in the first instance under said reduced speed conditions of the motor.

11. In a push button elevator control system, the combination with a car, of a reversible motor for driving said car, speed controlling means for said motor including low speed and high speed connections therefor, a plurality of push/button switches within the car and at the respective landings, means cooperating with the respective push button switches for controlling the direction of operation of said motor and for automatically commutating the low speed and high speed connections of the latter, said means comprising a selector switch driven by said motor at a speed proportional to the speed of said car, a normally closed limit switch carried by the car and cams in the hoistway adjacent said switch, e ectromagnetic means controlled by said selector switch for normally retiring said limit switch and operable to insure release of the latter upon movement of the car to a point intermediate a preselected landing and the next preceding landing, and means controlled simultaneously by said selector switch to insure low speed conncctions for said motor, said limit switch being thereafter opened by a cam prior to arrival of the car at said preselected landing to immediately eitect accurately positioned stopping of the car at said landing in the first instance.

12. I n a push button elevator control systcm. the combination with a car, of a reversible motor for driving said car, speed controlling means for said motor including low speed and high speed connections therefor,

a plurality of push button switches within the car and at the respective landings, means cooperating with the respective push button switches for controlling the direction of operation of said motor and for comlnutating the low speed and high speed connections, said means comprising a selector switch driven by said motor at a speed proportional to the speed of said car, a normally closed limit switch carried by the car and cams in the hoistway adjacent to the respective landings tending to open said switch, and electromagnetic means controlled by said selector switch for retiring said limit switch pcndingmovement of the car to a point ll'ltt'llllt'tlltltt a preselected landing and the next preceding landing. whereupon said hnnt switch is opened by the cam adjacent to said preselected landing to effect accurate stopping of the car, said selector switch being operable to insure interruption 01 said high speed connections and establishment of said low speed connections prior to stopping of said car.

13. In a push button elevator control system, the combination with a car, of a reversible motor for driving said car, speed controlling means for said motor including low speed and high speed connections therefor, a plurality of push button switches withinthe car and at the respective landings,means cooperating with the respective push button switches for controlling the direction of operation of said motor and for commutating said low speed and high connections, said means comprising a selector switch having an automatically adjustable connection with said motor for driving of the former at a speed proportional to the speed of said car, a normally closed limit switch carried by the car and cams in the hoistway adjacent to the respective landings tending to open said-switch, and

electromagnetic means, controlled by said selector switch for normally retiring said limit switch and operable to release the latter during approach of the car to a point intermediate a preselected landing and the next preceding landing, whercupon said limit switch is opened by the cam adjacent to said preselected landing to effectaccurately positioned stopping of the car.

14, In a push button elevator control system, the combination with a reversible motor having low speed and high speed connections, of a car'to be driven thereby, a selector switch and a belt' and pulley connection between said motor and said switch for driving the latter at a speed proportional to and in a direction corresponding with the direction of movement of said car, said switch being operable automatically to commutate said low speed and high speed connections during approach of the car to a predetermined landing, and means 'for positively limiting the degree of movement of said selector switch in opposite directions to thereby provide for automatic adjustment of the latter at each limit of travel of the car.

15. In a pushbutton elevator control system, the combination with a variable speed reversible motor. of a car to be driven thereby, a plurality of push button switches with switch to insure a predetermined reduced speed of said motor prior to arrival of said car at a predetermined landing, and means comprising a switch on said car and a cam adjacent to said landing for insuring accurately positioned stopping of the car at said landing under said reduced speed conditions.

16. In a push button elevator control system, the combination with a variable speed reversible motor, of a car to be driven thereby, a plurality of push button switches within the car and at the respective landings, a selector switch and an automatically adjustable connection betwen said motor andsaid switch for driving the latter ata speed proportional to and in a direction corresponding with the direction of movement ofsaid car,'said sele'ctor switch being adapted to cooperate with the respective push button switches for preselecting the direction and approximate duration of operation of said motor, means controlled by said selector switch to insure a predetermined reduced speed of said motor prior to arrival of said car at a preselected landing, and means comprising a switch on said car and a cam adjacent to said landing for insuring accurately positioned stopping of the car at said landing under said reduced speed conditions, said last mentioned switch being normally closed and having electromagnetically operable means for moving and holding the same bodily out of alinement with said cam pending a given operation of said selector switch prior to arrival of the car at said landing.

17. In a push button elevator control system, the combination with a car, of a reversible motor for driving the same, a plurality. of push button switches and an oscillatory selector switch cooperating therewith to control the direction of travel and destination of said car, said selector switch comprising a pair of conducting segments and contacts to be sequentially engaged therewith or disengaged therefrom, a belt and pulley connection between the motor and said selector switch to vary the position of the latter in accordance with variations in the position of the car, and means for positively limiting the degree of oscillatory movement of said selector switch to provide for automatic adjustment thereof in accordance with the position of the car.

18. In a push button elevator control systom, the combination with a reversible motor, low speed and high speed windings therefor, resistances to be included in or excluded from the circuits of said windings respectively and means for commutating said resistances, a plurality of push button switches located within the car and at the respective landings, means forpreselecting the direction of movement and destination of the car, said means comprising relays for controlling the forward or reverse operation of said motor, an

oscillatory selector switch having an angular position approximately corresponding with the position of the car for cooperation with the respective push button switches to control the operation of said direction relays, means for automatically connecting and accelerating the motor though said low speed windings and for thereafter connecting and accelerating the motor through said high speed windings, a normally closed limit switch secured to the car and cams in the hoistway adjaoent to the respective landings to open said switch when engaged thereby, electromagnetically operable means controlled by said direction relays to effect bodily movement of said switch out of alinement with said cams, said selector being adapted upon movement of the car to a predetermined point to effect disconnection of said high speed winding to provide for low speed operation of the motor, said electromagnetic means being also simultaneously deenergized to provide for movement of said limit switch into alinement with the next succeeding cam in the hoistway to provide for opening of said switch with consequent stopping of the car when the latter is accurately positioned at said predetermined landing.

In witness whereof, I have hereunto subscribed my name.

EDWIN W. SEEGER.

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