US2699226A

US2699226A - Elevator control system

Info

Publication number: US2699226A
Application number: US293604A
Authority: US
Inventors: Bruns William Henry
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1952-06-14
Filing date: 1952-06-14
Publication date: 1955-01-11
Anticipated expiration: 1972-01-11

Description

Jan. 11, 1955 w. H.YBRUNS ELEVATOR CONTROL SYSTEM Fi l ed June 14. 1952 v s She'ets-Sheet 1 I Ill /I/I V/l a we pHLT

mm DHL W/Lt/AM HEMP) Bel/N5 INVENTOR BY fix aawu ATTORNEY Jan. 11, 1955 w. l-1.BRUN$ 2,699,226

- ELEVATOR CONTROL SYSTEM Filed June.l4. 1,952 7 5 SheetsSheet 2 AC5 AC6 Q CFMA FRTI ' FRA 1 FRPSI FRFZ RFA- FH WILLl/IM HENEVBPUNS INVENTOR BY ATTORNEY Jan. 11, 1955 w. H. BRUNS 2,699,226;

ELEVATOR CONTROL SYSTEM Filed June 14. 1952 5 Sheets-Sheet 4 BY ATTORNEY United States Patent ()1 ELEVATOR CONTROL SYSTEM William Henry Bruns, Lincolndale, N. Y., assignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application June 14, 1952, Serial No. 293,604

11 Claims. (Cl. 187--29) The invention relates to control systems for movable bodies, especially systems for controlling the operation of elevator cars.

In the control of an elevator car, a great many of the operations involved depend on the position of the car in the hoistway, especially with relation to the floors at which stops are to be made. Mechanism is provided for effecting such control operations and is usually located in the pent house and driven from the elevator car. Such mechanisms have been termed selectors or in some cases floor controllers. Among the operations controlled by such mechanisms as applied to a system in which the car stops automatically at floors for which calls are registered are the picking up of the calls, lighting of hall lanterns, initiating slow down of the car at floors at which calls are picked up, automatic cancellation of calls as they are answered, direction set up, reversal at farthest call, acceleration and retardation of the elevator car and operating car position indicators. In view of these and other operations subject to the selector mechanism, a considerable amount of apparatus is involved.

It is the object of the invention to provide an elevator control system utilizing control mechanism of the above character which is of simple construction, economical to manufacture and install, and in which various control oplerations are effected electrically instead of mechanica y.

The invention involves the utilization of a voltage difference between a voltage representing the actual position of the car in the hoistway and a voltage related to the floors served by the car for effecting the actuation of control mechanisms for performing various selector operations.

In carrying out the invention in accordance with the embodiment which will be described, as applied to effecting certain operations dependent on the exact position of the car, as for example for operating a car position indicator, the voltage difference is that between the car position voltage and a floor reference voltage and this voltage difference is utilized to cause the floor reference voltage to be in accordance with car position. As applied to effecting operations which take place in advance of the car, such as picking up and automatically cancelling calls, lighting hall lanterns at floors at which stops are to be made, initiating slow down and controlling retardation, a biasing voltage is added to cause the reference voltage to represent a position in advance of the car.

The car position voltage is taken off a potentiometer, the slider of which is actuated in accordance with the movement of the elevator car. This potentiometer serves as a master potentiometer. The floor reference voltage also is taken off a potentiometer connected in bridge relationship to the car position (master) potentiometer. The position of the slider of the floor reference potentiometer is determined by the voltage diiference existing across the diagonal of the bridge connecting the two sliders. The advance voltage is taken off a separate potentiometer, also connected in bridge relationship to the master potentiometer. The slider of this advancer potentiometer is advanced with respect to the slider of the car position potentiometer by a biasing voltage superimposed in the bridge diagonal circuit. The floor reference and advancer potentiometers are in the nature of slave potentiometers. The sliders of the slave potentiometers are driven by motors subject to the voltages of their respective bridge diagonal circuits. In the arrangement illustrated the potentiometers are connected across alternating current supply lines and the resultant voltage of the bridge diagonal is amplified and applied to the slave potentiometer actuating motor. Where voltage exists between the two sliders the motor actuates the slider of the slave potentiometer in a direction determined by the phase of the diagonal voltage to reduce this voltage to zero, whereupon the motor comes to a stop.

One feature of the invention is to provide on a slave potentiometer, points representative of the floors served by the car and to provide voltage differences between such points in accordance with the heights of the floors which they represent.

Another feature of the invention is to limit the amount of advance movement of the slider of the advancer potentiometer for full speed operation and to cause less advance to take place on shorter runs where full speed is not attained.

Still another feature of the invention is, when a call for a floor is picked up, to provide a voltage across the diagonal of the advancer bridge which accurately meas ures the distance of the car from the floor at which the stop is to be made.

Another feature is the utilization of this accurate voltage difference to determine on full speed runs the point at which retardation of the elevator hoisting motor begins and on runs of less than full speed the point at which acceleration of the elevator hoisting motor is discontinued.

Still another feature is the utilization of this accurate voltage for distance control of the retardation of the car.

Other features and advantages of the invention will be apparent from the following description and appended claims.

In the drawings:

Figure 1 is a simplified schematic representation of an elevator installation in accordance with the invention;

Figures 2, 3, 4 and 5 taken together constitute a simplified wiring diagram of the circuits for the elevator installation of Figure 1; and

Figure 6 is a key sheet showing the electromagnetic switches in spindle form.

For a general understanding of the invention reference may be had to Figure 1, wherein is illustrated by way of example an elevator installation in which the car serves five floors. The floors are designated generally as L and differentiated by appended reference characters. The car is raised and lowered by means of an electric hoisting motor 10, which motor drives a traction sheave 11 over which pass hoisting ropes 12 for the car 13 and counterweight 14. Current for the motor is provided by a variable voltage generator of a motor generator set 15. An electromechanical brake BR is provided and is applied to effect the stopping operation and to hold the car when at rest.

The car position potentiometer CP is driven preferably by means of a tape 16 attached to the car and counterweight and having teeth thereon for engaging teeth on the potentiometer driving Wheel. This potentiometer may be in the form of a helix with its slider arranged to move in a helical path as is well understood. The floor reference potentiometer FRP will be described as controlling a car position indicator 17 and as such may be located at the first floor as indicated. Two advancer potentiometers are utilized, one among other things for picking up landing calls and termed a landing call finder potentiometer. Such potentiometer designated LFP is located on the control panel 18 in the pent house. The other advancer potentiometer is utilized in picking up car calls and is termed a car call finder potentiometer. Such potentiometer, designated CFP, is located on the elevator car. Further description of such apparatus will be given along with the description of the control circuits.

The invention will be described as applied to a system in which the car is provided with an attendant or in which no attendant is provided. On with attendant operation, the doors are closed and the car started in response to a start control operated by the car attendant. For convenience, it will be assumed that on without attendant operation, the doors are closed and the car started in response to calls registered by the passengers themselves, although it is to be understood that the latter operation contemplates closing the doors and starting the car from terminals by a dispatching system, with the door closmg and starting operations at intermediate fioors takir 1g place automatically upon expiration of the door time interval.

The car is provided with a car operating panel on which are located a plurality of control switches for op oration by the passengers themselves on without attendant operation and for operation by the car attendant on with attendant operation. These switches include among others a plurality of push buttons, one for each floor above the lower terminal, hereinafter termed car buttons, for registering car calls for both without attendant operation and with attendant operation and a start control button for with attendant operation.

The car buttons are designated C and have numerals appended thereto as indicative of the floors for which the car buttons are provided.

Controls are provided at the floors to enable intending passenges to register landing calls, an up control and a down control D being provided at each intermediate floor, one control D at the top terminal floor and one control U at the bottom terminal floor. Differentiation between these controls is had by appended reference characters indicative of the floors. These call registering controls will hereinafter be termed landing buttons. Hall lanterns are also provided at the landings. The hall lanterns are designated HL and differentiated by reference characters corresponding to the floors for which they are provided and by the letters U and D, in accordance with whether up or down hall lanterns.

To facilitate disclosure of an application of the invention, the control system illustrated has been extremely simplified as compared with control systems utilized in commercial installations. It is to be understood that in applying the invention to control systems used commercially, many changes may be made, especially in adapting the invention to the more comprehensive circuits and to control features and apparatus not here shown.

The electromagnetic switches employed in the system illustrated are designated as follows:

A Start and stop switch DD Down direction switch DG Direction holding switch EA First speed switch EAX First speed switch timing relay EB Second speed switch EBX Second speed switch timing relay EC Third speed switch ECX Third speed switch timing relay EX Auxiliary speed switch F Floor switch FL Late call floor switch GK Notch back switch H Brake and field switch HI Highest call switch HR Highest call reversal switch SM Start and stop control switch UD Up direction switch Throughout the description which follows, these letters will be applied to the coils of the above designated switches. Also, with reference numerals appended thereto, they will be applied to the contacts of these switches.

The circuits are shown in straight, i. e., across-theline, form in which the coils and contacts of the various switches are separated in such manner as to render the circuits as simple and direct as possible. The relationship of the coils and contacts may be seen from Figure 6 wherein the switches are arranged in alphabetical order with the coils and contacts of the various switches positioned on spindles in alignment with their positions in the wiring diagram. Numbers following dashes after the reference characters on the spindle sheet indicate the number of the figure in which the coil or contacts appear.

The electromagnetic switches are illustrated in deenergized condition, switches DG, GK and SM Which are of the latching type being shown in reset condition. Each of these switches has two coils, one an operating coil and the other a reset coil. Each of switches A, BA, BB and EC has two coils, one an operating coil and the other a hold-in coil.

Referring to the landing call registering circuits of Figure 3, each of the landing buttons in the preferred arrangement comprises an electronic tube and a fixed button connected to the tube envelope with the circuits arranged so that the tube breaks down in response to manual touch of the fixed button and remains conductive, thereby registering the call and enabling the touch to be dlscontinued. These electronic tubes are cold cathode gas tubes, the type having a wire anode extending to within a short distance of the glass envelope of the tube, such as the RCA 1C2l, having been found satisfactory. With such a tube, the button TB, see landing button D3, is connected to the tube envelope adjacent the anode. RUL and RDL are loading resistors for the tubes. The voltage values of the direct current supply lines for such tubes are indicated in Figure 3 of the drawings, line B being the reference voltage and thus Zero. The R. M. S.

values of the alternating current voltages indicated in Figure 3 are:

volts from AC1 to B50 volts from GR to B+70 105 volts from AC2 to B+70 It is to be noted that the anodecathode circuit of the tube of each landing button is from line B+150 through the tube and its load resistance to line B. The direct current voltage thus applied to the tube is not sufficient to break down the tube. However, upon an intending passenger touching the landing button, a circuit is established from ground GR through the secondary of transformer T1 and by Way of line B+150 to the anode of the tube and thence from the tube envelope by way of the body of the intending passenger back to ground. As a result, sufiicient alternating current voltage is applied between the anode and the tube envelope to break down the tube. When the tube fires, it becomes illuminated to indicate that the landing call is registered.

Each car button C when pressed is held pressed by a magnet CBM common to these buttons. The starting button SB in the car may be provided with other contacts to effect the operation of the doors. Car position indicator lamps are illustrated as glow discharge lamps and designated generally by PC and differentiated by reference characters corresponding to the floors for which they are provided. A plurality of floor relays are provided, one for each floor and designated 1F, 2P, 3P, 4F and TF for the first, second, third, fourth and top floors respectively. Resistors are designated generally as R, rectifiers as V and condensers as Q.

Other electronic tubes are employed in the system.

These include tubes arranged in call pick-up and stop initiating circuits. Two of these tubes are provided, one for car calls designated CC? and one for landing calls designated LCP. Also a tube is provided in the circuits for automatically cancelling calls registered by the landing buttons when these calls are answered. This will hereinafter be termed landing call cancelling tube and designated LCC. Also a tube is provided in the highest call return circuits which will be termed highest call return tubes and designated HCR. Tubes CCP, LCC, LCP and HCR are preferably cold cathode gas tubes of the RCA OA4G type. The control of an elevator car in response to electronic touch button tubes in which system tubes CCP, LCP, LCC and HCR are utilized is described in detail in the patent to Bruns No. 2,468,289 granted April 26, 1949. Tubes TA, TEA, TEE, TEC and TGK are also cold cathode gas tubes of the RCA OA4G type and are arranged in the hold-in circuits for switches A, EA, EB 1and EC and the reset circuit for switch GK respect1ve y. Referring to Figures 3, 4 and 5, the operation of startmg and stopping the car will first be described. The door operating circuits are not shown. The elevator hoisting motor is illustrated as a direct current motor, its armature being designated MA and its field winding MP. A variable voltage direct current generator is illustrated for supplying current to the hoisting motor, the generator armature being designated GA, its separately excited field winding GP and its series field winding GSF. Direct current for the field windings is obtained from supply lines and which also supply current for the switches of Figure 4. With attendant operation will first be assumed, changeover switch CO being shown for that condition. The circuits are shown for the car positioned at the first floor under which condition the car is set for upward travel and thus switch DG is operated and switch HR is dropped out.

To start the car, start button SB is pressed. This causes the closing of the doors and completes a circuit for the operating coil of switch SM. Switch SM operates to engage contacts 8M3, completing a circuit for the coil of switch A. This switch operates to engage contacts A1 which, upon closure of the doors and consequent engagement of car door contacts CD and hoistway door contacts HD (the hoistway door contacts being connected in series relation and represented by a single pair of contacts), completes a circuit through contacts DGl for the coils of switches UD and H. Switch UD engages contacts UDl and UD2 to complete a circuit for generator field winding GP for excitation of the generator of the proper polarity for upward car travel. Switch H engages contacts H1 completing a circuit for the brake release coil BR, releasing the brake. As a result, the car is started in the up direction.

Incident to the starting operation, contacts 8M8 also complete a circuit for the coil of switch GK. This switch engages contacts GK3 and GK4, short circuiting portions of generator field resistance RG and separating contacts GKS to remove the short circuit for a portion of the section of resistance RG subject to contacts EA2. Also contacts F1 engage incident to advancer operation, as will be explained later, to complete a circuit through contacts A1 for the coil of switch EX, causing this switch to be operated.

While the car was standing at the first floor, switches EAX, EBX and ECX were operated, the circuit for the coil of switch EAX being through contacts H2, that for the coil of switch EBX being through contacts EAXl, and that for the coil of switch ECX being through contacts EBXl. Upon the starting of the car, the separation of contacts H2 breaks the circuit for the coil of switch EAX. This switch is delayed in dropping out by the discharge of condenser Q5. Upon dropping out it engages contacts EAX2, completing a circuit through contacts GK2 and SM10 for the coil of switch EA. This switch operates to engage contacts EA2 to short circuit a step of resistance RG with resultant increase in speed of the car. Switch EAX also separates contacts EAXI which breaks the circuit for the coil of switch EBX. Thus upon the time interval provided by condenser Q6, switch EBX drops out to cause operation of switch EB to short circuit another step of resistance RG, further increasing the speed of the car. In a similar manner switch. EC is operated, short circuiting the final step of resistance RG to bring the car up to full speed.

Assume now that before button SE is operated to start the car, an intending passenger at the fourth floor wishing to be carried in the up direction touches up landing button U4. This causes the tube to break down, the circuit being through body capacity to ground, thereby applying alternating current obtained from transformer T1 across the tube envelope and anode. As a result an up call is registered for the fourth floor. Assuming that the car gets up to full speed in a four floor run, as the car arrives at call pick-up distance from the fourth floor, switch 4F operates to engage contacts 4P5, as will be seen from later description. This cause voltage equal to the potential drop across resistor RUL4 plus the potential difference between lines B and B-50 to be applied across the control electrode and cathode of tube LCP. At the same time switch F operates to engage contacts F4 to complete the anode-cathode circuit of tube LCP from line AC1 to line 13-50 through contacts EX6, FLI and SMll and the reset coil of switch SM. This tube breaks down due to the potential applied to its control electrode. This causes switch SM to be reset, picking up the fourth fioor call. Switch SM, upon being reset, engages contacts SMl which, owing to the fact that contacts 4P2 are now engaged, causes lighting of the up fourth floor hall lantern UHL4.

The anode and cathode of tube LCC are connected across resistor RLCDl which with resistor RLCD2 forms a voltage divider connected across lines 13-56 and AC2. As a result about three-quarters of the voltage across these lines is applied across the anode-cathode of tube LCC. As the switch SM is reset, contacts SM9 engage to place on the control electrode of tube LCC the cathode potential of tube U4. The circuit is from the cathode through contacts 4P5, HR6 and SM9 and the secondary of transformer T3 to the control electrode. This potential, with the alternating current voltage from transformer T3 superimposed thereon, is suflicient to cause tube LCC to fire. This raises the cathode potential of tube LCC to a value tube drop below the anode potential. Due to blocking rectifier VLC permitting the flow of current from the cathode of tube LCC to the cathode of tube U4, the potential of the cathode of tube U4 is raised with respect to its anode, causing this tube to be extinguished. Thus the up call at the fourth floor is automatically cancelled immediately the call is picked up. The cancelling of the call drops the potential of the cathode of tube U4 to that of line B. As a result, tube LCC is extinguished during the negative portion of the alternating current cycle and does not refire.

Switch SM, upon being reset, separates contacts SMS and engages contacts SMS, transferring the control of switch A from its operating coil to its hold-in coil, completing the circuit for the hold-in coils of switches EA, EB and EC and breaking the circuit for the operating coil of switch GK. As will be seen from later description, under the assumed conditions switch GK is reset as the car arrives at a certain distance from the fourth floor and thereafter switches EC, EB and EA drop out in sequence to gradually reduce the strength of the generator field to slow down the car. As the car arrives at the floor switch A drops out to separate contacts A1, breaking the circuit for the coils of switches UD and H with the result that the circuit for generator field winding GE is broken and the brake is applied to bring the car to a stop.

Stopping of the car in response to a car call is effected in a similar manner. Assume again that the car is positioned at the first floor and assume further that before the attendant presses start button SB to close the doors and start the car, a passenger enters the car and announces the fourth floor as his destination. The attendant thereupon presses car button C4 which is held in by car button magnet CBM. As the car arrives at call pick-up distance from the fourth floor, slider CFPSZ of potentiometer CFP engages fourth floor contact CP4, connecting the control electrode of tube CC? to line B+1S0. At the same time contacts F4 engage completing the anode-cathode circuit of tube CCP, causing this tube to break down and the reset of switch SM. As a result, the fourth floor up hall lantern is lighted and the car is slowed down and brought to a stop at the fourth floor.

It is believed that it will be understood from the above description that during upward travel of the car, stops are made at all floors for which car calls and up landing calls are registered. The car calls are picked up upon the engagement of slider CFPSZ with the stationary contacts C? for the floors for which car calls are regis tered and the up landing calls are picked up upon the operation of relays 1F to TF for the floors for which such landing calls are registered.

A stop may be made during upward travel in response to a down landing call for a floor provided no up landng call exists for that fioor and no call exists for a floor .bove. Assume again that the car is at the first floor and that a down call is registered for the fourth floor. As a result the potential drop across loading resistor RDL4 plus the potential existing between lines B and B-50 is applied across the control electrode and cathode of tube HCR by way of blocking rectifiers VD4, VI-IL3 and VHLZ and contacts 1P5, closed when the car is at the first floor. This causes tube HCR to be fired and as a consequence switch H] to be operated. Incident to the starting of the car from the first floor, contacts 1P5 separate and contacts F2 engage. Condenser QHCR insures maintaining switch H] in operated condition during this transition. The same is true as the car passes the second and third floors where there is transition between contacts F2 and 2P4 and 31 4. However, upon the separation of contacts F2 as the car reaches call pick-up distance from the fourth floor, the circuit to the control electrode of tube HCR is broken inasmuch as no up landing call is registered for the fourth floor and no landing call is registered for a floor above so that the engagement of contacts 4P4 does not establish another :onnection to the control electrode and inasmuch as no connection to the control electrode is established by way of fifth floor car button CT. As a result, switch H] drops out and enga es contacts H12. completing a circuit through contacts 8M7, EX4 and D69 for the coil of switch HR. This switch operates to separate contacts H126 and engage contacts HRS. gagement of the latter contacts, the down fourth floor call is picked up, the call is reset and the car is caused to be slowed down and come to a stop at the fourth floor as above described. Also, switch HR separates contacts HRZ and engages contacts I-IRI so that a circuit is completed by way of circuits SMT and 4F]. for the down hall As a result of the en lantern DHL4 at the fourth floor. Upon the dropping out of switch EX in the stopping operation, contacts EXF: engage completing a circuit through contacts HR?) and DG8 for the reset coil of switch DG, causing this switch to be reset and thus set the car for downward travel.

Switch DD is operated in response to operation of the start button when the car is set for downward travel inasmuch as contacts DGZ are engaged. Switch DG also engages contacts 13-610 to establish a holding circuit for the coil of switch HR. As a result the car is maintained set for downward travel until the first floor is reached, the operation of switch DG to set the car for upward travel being dependent upon the engagement of contacts IE2 and EX3 which takes place when the car reaches the first floor. It is to be understood that during the downward travel of the car, the car stops in response to car calls and down landing calls. If a down landing call is registered at the second floor for example, upon the engagement of contacts 2P3 the call is picked up and switch SM is reset, causing the car to be brought to a stop at the second floor. Also, the engagement of contacts 2P1 and 5M1 causes the lighting of the down hall lantern DHLZ. If instead a second floor car call is registered, the call is picked up upon the engagement of slider CFPSZ with contact CP2, causing the reset of switch SM and the slow down and stopping of the car at the second floor. The stopping of the car at the first floor on its downward trip is effected by the engagement of slider CFPSZ and stationary contact CPI permanently connected to line B+150. The operated car buttons are released each time the direction of car travel is changed, due to the deenergization of the car button magnet CBM by the breaking and reclosing of its circuit upon operation or reset of switch DG.

When switch CO is thrown to its upper position, both the starting of the car and operation of switch SM is dependent upon the closing of the doors, which in a collective control system for example is dependent upon a call being registered. The picking up of the calls and stopping of the car, however, is the same as previously described.

Referring now to Figure 2, the potentiometers are illustrated as connected across alternating current mains designated AC5 and AC6, taken off main transformer MT supplied by lines L1 and L2. Each of potentiometers LFP, CFP and FRP is provided with tapped points which represent the various floors. Connected across these tapped points of potentiometers LFP, CFP and FRP are resistors FHRL, FHRC and FHRF respectively of relatively low ohmic value. Their ohmic values vary in accordance with the height of the floors for which they are respectively provided and thus fix the potential of these tapped points to be in accordance with the heights of the floors which they represent. Thus the tapped points may be equally spaced even though the floor heights vary. The sliders of these potentiometers are actuated by motors illustrated as two phase alternating current rnotors. The armature of the motor for actuating the floor reference potentiometer sliders FRPSI and FRPSZ is designated ERA and its field windings FREE and PRFZ. The armature of the motor for actuating the car call finder potentiometer sliders CFPSI and CFPSZ is designated CFMA and its field windings CFMPI and CFMFZ. The armature of the motor for actuating the landing call potentiometer sliders LFPSI and LFPS2 is designated ADA and its field windings ADFI and ADFZ. Field windings ADFl, CFMFI and FRFI are connected across lines AC5 and AC6 in series with condensers QAF, QCFM and QFR to provide fixed excitation in phase shift relation to the excitation provided by windings ADFZ, CFMF2 and FRF2 which is variable. Each of field windings ADFZ, CFMFZ and FRFZ is excited from the secondary of a control transformer, the exciting voltage of which is applied to an amplifier (indicated as in block form) which is connected to the field winding. The advancer amplifier is designated AAM, the advancer amplifier input transformer AT2 and the advancer amplifier power transformer ATl. The car call finder amplifier is designated CFA, its input transformer CFTZ and its power transformer CFTI. The floor reference amplifier is designated FAM, its input transformer FRTZ and its power transformer FRTI. ABT is the advancer biasing transformer while CPP is the car position potentiometer, the slider of which is actuated by the car.

For convenience, the operation of the floor reference potentiometer will first be described. With the car positioned at the first floor as indicated by the positions of the sliders, no voltage exists between sliders CPS and PRPSI, the connection between which represents the diagonal of the bridge formed by potentiometers CPP and FRP. As the car moves upwardly, sliders CPS moves to the right, causing a voltage between sliders CPS and FRPSl which is applied to the primary of transformer FRTZ. This voltage is amplified and applied to field winding FRFZ and is of the proper phase with respect to the excitation provided by winding FRFI to cause movement of slider FRPSl to the right. In this way, as the car moves upwardly, slider FRPSI is caused to follow slider CPS, substantially in synchronism with the car. When the car moves downwardly, the excitation of winding FRFZ is reversed, causing slider FRPSI to follow slider CPS. Thus potentiometer FRP is actuated substantially in synchronism with the car. This movement may be utilized for various operations, being illustrated as controlling a car position indicator, see Figure 5, where slider FRPSZ engages contacts CFPC to cause the successive lighting of lamps PC.

The operation of landing call finder potentiometer LFP will now be described. Assuming with attendant operation, when start button SB is pressed to initiate starting of the car, switch SM operates to engage contacts 8M2 and 8M4 and to separate contacts SM3 and SM6. The separation of contacts SM3 and reengagement of contacts 5M2 transfers the connection of amplifier AAM from rectifiers V1 and V2 to field winding ADFZ. The separation of contacts SM6 and engagement of contacts 8M4 transfers the connection of the primary of input transformer AT2 from floor accuracy resistor FAR to the secondary of biasing transformer ABT. This causes a voltage between sliders LFPSI and CPS which is applied through transformer AT2 and amplifier AAM to field winding ADFZ. This voltage is of a phase to cause movement of slider LFPSI to the right, thus advancing this slider with respect to slider CPS and thus with respect to the car.

The extent of the full advance of slider LFPSI is de termined by the characteristics of the particular installation, especially full running speed. As will be seen, potentiometer LFP also controls the lighting of the hall lanterns. It is desirable to give sufficient advance lighting of the hall lanterns particularly in plural elevator installations to provide time for the passenger to place himself in front of the answering elevator, thereby avoiding loss of tlme waiting on passengers. The advance may be greater than car stopping distance but in such case this increases chances of registering calls too late to intercept the car. Thus the amount of advance is compromised between these two factors and is determined by the point at which connection is made to resistor R7. For example, on installations of 500 F. P. M., this advance would be 12 feet whereas on installations of 1200 F. P. M., it would be 60 feet.

As will be explained below, the advance may be halted by picking up a call before full advance is obtained. If not brush LFPSl is maintained by the biasing voltage in full advance of brush CPS as the latter is moved by the car. As previously explained, on with attendant operation, the advance takes place during the closing of the doors. If the doors close before the full advance is had, the rate of advance is set to insure picking up of the call the desired distance in advance of the car. This is also the case on without attendant operation where the advance does not start until the doors reach closed position. When the car is set for upward travel, as above assumed, contacts D64 are engaged which causes the phase of the biasing voltage to be such as to move slider LFPSI to the right. When the car is set for downward travel, contacts DGS are engaged, causing the advance movement to be to the left. Thus in each case, the advance of slider LFPSI with respect to slider CPS is in accordance with the direction of car movement.

Slider LFPSZ of the landing call finder potentiometer engages contacts LFPCL LFPCZ, etc, in succession to cause the operation and dropping out of floor relays 1P, 2P, etc. Thus upon the operation of a floor relay for which a landing call is registered for the direction of car travel, the call is picked up to cause reset of switch SM. Thus contacts 8M4 separate, removing the biasing voltage, and contacts SM2 separate to disconnect field winding ADF2, bringing the advancer motor to a stop with slider LFPS2 in engagement with the stationary contact. This enables the hall lantern to be lighted and the call to be automatically cancelled, as previously described. In this connection, switch P, which operates each time a floor relay is operated, separates contacts F3 to disconnect the coil of switch FL. Switch FL is delayed slightly in dropping out by the discharge of condenser Q8. Upon dropping out it separates contacts FLl, thereby preventing the establishing of the reset coil circuit for switch SM, thus obviating picking up a late call which might cause the car to stop too far beyond the floor.

The slider CFPSl of the car call finder potentiometer is tied to slider LFPSI of the landing call finder potentiometer through transformer CFTZ in the same manner that slider FRPSI is tied to slider CPS, as explained above. As movement of slider LFPSI takes place, a voltage is applied to field winding CFMFZ through amplifier CFA to cause operation of car call finder motor to move slider CFPSl in step with slider LFPSI. Slider CFPSZ is moved along with slider CFPSI and engages contacts CP (Figure 3) for the various floors. Upon the engagement of a contact for a floor for which a car call is registered, switch SM is reset to remove the biasing voltage and to disconnect field winding ADFZ to bring slider LFPSI and thus sliders CFPSI and CFPSZ to a stop.

When switch SM is reset on picking up a landing call or car call, it also engages contacts SM6 to subject the primary winding of transformer AT2 to a voltage in an amount determined by the distance of the car from the floor for which the call is picked up. This voltage is obtained from floor accuracy resistor FAR and the amount is determined by the particular floor relay which is operated. For example, with the car set for upward travel, when a call is picked up at the fourth floor, contacts 4P6 are engaged to cause a voltage determined by the voltage at contacts 4P6 with respect to the voltage at slider CPS to be applied to transformer AT2. Whereas the voltage between sliders LFPSI and CPS only roughly represents the distance of the car from the floor, the floor points on resistor FAR are accurately set, as by a galvanometer in the bridge circuit at the time of assembly. Thus a more accurate voltage measurement of the distance of the car from the floor at the time a call is picked up is applied to the transformer. As switch SM is reset it engages contacts 8M3 which causes this accurate voltage, amplified by amplifier AAM, to be applied to rectifier V1 and V2. Thus a direct current voltage, obtained from the output of these rectifiers and representing the distance of the car from the floor, is applied to lines DC1 and DC2.

The direct current voltage thus obtained is applied by way of contacts SM5 in series with an alternating current biasing voltage taken off resistor R8 to resistor R6. Connections are taken off resistor R6 to the control grids of tubes TA, TEA, TEB and TEC. The anode-cathode circuits of these tubes are across lines AC5 and AC6 and include the hold-in coils of switches A, EA, EB and EC respectively. On full speed runs, contacts A2, EAl, BB1 and ECl are all engaged and maximum voltage is obtained from lines DC1 and DC2 with the result that sufficient voltage is applied across the grid-cathode of each tube to cause the tube to fire. Thus upon the engagement of contacts SM5, the hold-in coils of these switches are energized, it being understood that contacts SMS engage before the separation of contacts SMS to insure the holding in of switch A by its hold-in coil. On less than full speed runs, some of these switches, say switch EC, may not operate and thus will not be held in by their hold-in coils. Also, even if operated the voltage across the grid-cathode of the tube may be insufficient to hold it operated. This will be better understood as the description proceeds.

The direct current voltage from rectifiers V1 and V2 is also applied to resistors R2 and R5 and condenser Q1. Thus the potential drop across them at the instant switch SM is reset is proportional to the distance of the car from the floor at which the stop is to be made. A biasing voltage is taken off resistor R3, the voltage drop across this resistor being constant and due to the secondary voltage of transformer GKT. The sum of this biasing voltage, the voltage drop across the upper portion of resistor R2 and the voltage drop across the upper portion of resistor R5 is applied across the cathode and grid of tube TGK, the anode-cathode circuit of this tube being subject to the voltage of the secondary of transformer GKT. The polarities of ti e potential drops across the portions of resistors R2 and R5 are in opposition, that obtained from resistor R5 trying to fire the tube and that obtained from resistor R2 opposing the firing. As the car approaches the floor, the voltage at the slider CPS approaches the voltage at contacts of the operated floor relay, say contacts 4P6 for the fourth floor. As a result, the voltage drop across resistor R2 decreases while that across resistor R5, due to the large capacity of condenser Q1, remains substantially in accordance with the distance of the car from the floor for which the call is picked up. The net result is that when the car reaches a certain distance from the fioor, determined by the length of the run, the potential drop taken from resistor R2 diminishes to a point where tube TGK breaks down to complete the circuit for the reset coil of switch GK.

Assuming a full speed run, the reset of switch GK causes separation of contacts GK3 to insert a portion of resistor RG in circuit with generator field winding GF, initiating slowing down the car. At the same time, contacts GK2 separate to render switches EA, EB and EC subject to their holding coils alone. As the car approaches still closer to the floor the potential drop across the gridcathode of tube TEC decreases to a point where the tube does not refire upon the next alternating current cycle with the result that switch EC drops out to separate contacts EC2, inserting a further portion of resistor RG in circuit with the generator field winding to further slow down the car. It is to be noted that owing to the fact that contacts GK4 are separated, the amount of resistor RG thus inserted is greater than was short circuited by contacts EC2 during acceleration of the car. As the car approaches still closer to the floor, the potential drop across the grid-cathode of tube TEB decreases to a point where the tube does not refire, causing the dropping out of switch EB. As a result, contacts E132 separate to insert a further portion of resistor RG in circuit with the generator field winding to cause further slow down of the car. As the car arrives at a point still closer to the floor, switch EA is dropped out in a similar manner to separate contacts EA2 to further slow down the car. Due to the engagement of contacts GKS the amount of resistance inserted by the separation of contacts EA2 is less than that which was short circuited for acceleration of the car. As the car arrives at the floor, switch A is similarly dropped out causing the dropping out of switches UD and H to break the circuit for the generator field winding and apply the brake to bring the car to a stop.

On less than full speed runs, the voltage drops across resistors R2 and R5 at the time the call is picked up is less than on full speed runs. The net result is that the distance of the car from the floor at the time switch GK is reset is less, the shorter the length of the run. On less than full speed runs, the reset of switch GK interrupts the acceleration of the car. Also, upon the separation of contacts GK2, only those of switches EA, EB and EC which are operated at the time switch GK is reset and for which there is suflicient voltage to fire their tubes TEA, TEB and TEC respectively will remain operated. This provides the desired control of the acceleration of the car and distance control of the dropping out of the operated speed switches and switch A.

The arrangement whereby the difference in voltage between the voltage representing the position of the car and the voltage representing the distance of the car from the stopping floor is utilized to control switches GK, EC, EB, EA and A serves as a servo system for controlling the retardation and stopping of the elevator car. The motion of the elevator car forces the car to slow down on a distance control basis and finally to come to a stop at a fixed point, thus providing a closed cycle system. The diiference between these two voltages dictates the generator voltage. The generator armature and motor armature being connected in a loop circuit forms another closed cycle system in which the difference between the generator voltage and counter e. m. f. of the motor determines the speed of the motor.

Thus, it is seen that there is provided control mechanism for elevators which performs electrically the functions of mechanical selectors and floor controllers in a simple and economical manner. Also, the mechanism may be economically manufactured and installed. Utilization of the control mechanism dispenses with a considerable amount of hoistway wiring and enables other wiring to be done at the factory. Furthermore, in a plural elevator installation, these control mechanisms for all elevators may be located together, thus simplifying the cross connecting of the circuits and enabling this wiring also to be done at the factory.

While alternating current supply lines have been illustrated for the potentiometers, it is to be understood that direct current lines may be utilized in which event direct current amplification and motors will be employed. Levelling mechanism has not been previously referred to, but it is to be understood that the voltage difference in the diagonal of the bridge formed by potentiometer CPP and resistor FAR may be utilized for this purpose, as by acting through amplifier AAM to operate up and down levelling switches. Also, any one of a plurality of known levelling arrangements may be employed. If desired, conventional push buttons acting through floor relays may be utilized instead of touch buttons for registering landing calls.

As many changes could be made in the above construction 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 shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a pair of resistors connected in bridge relationship across said source, one for car position reference and the other for fioor position reference, means for moving the end of the bridge diagonal on the car position reference resistor side of the bridge in accordance with movement of the car, means responsive to a voltage difference across said diagonal for moving said other end of said diagonal, and means for applying a voltage to said diagonal to cause said other end thereof to advance a fixed amount with respect to said one end thereof incident to the starting of the car so as to cause movement of said other end in said advanced position with respect to said one end upon movement of said one end during movement of the car.

2. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a pair of resistors connected in bridge relationship across said source, one for car position reference and the other for floor position reference, means for moving the end of the bridge diagonal on the car position reference resistor side of the bridge in accordance with movement of the car, means responsive to a voltage difference across said diagonal for moving said other end of said diagonal, means for applying a voltage to said diagonal to cause said other end thereof to advance a fixed amount with respect to said one end thereof incident to the starting of the car so as to cause movement of said other end in said advanced position with respect to said one end upon movement of said one end during movement of the car, and means responsive to the arrival of the car a distance corresponding to said advance from the floor at which a stop is to be made for discontinuing further movement of said other end of said diagonal so as to cause the advance to be taken up as the car comes to said floor.

3. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car to register car position, a resistor connected across said source, said resistor having tapped points representing said floors to provide sections of ohmic values corresponding to the heights of said floors, contacting means adapted to engage said tapped points when the car is stopped at the respective floors for which such points are provided, means responsive to the initiation of the starting of the car for applying a biasing voltage between said slider and contacting means, means responsive to the voltage difference between said slider and contacting means for advancing said contacting means with respect to said slider an amount determined by the value of said biasing voltage, and control mechanism actuated along with said contacting means for controlling the operation of the car.

4. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car, a floor reference resistor connected across said source, movable contacting means for said resistor, means responsive to a voltage difference between said slider and contacting means for moving said contacting means, means responsive to the initiation of the starting of the car for causing a voltage difference between said slider and contacting means for advancing said contacting means with respect to said slider, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call registering means for each floor, call pick-up means actuated by said contacting means for picking up calls which are registered, and means responsive to the picking up of a call for stopping movement of said contacting means.

5. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car, a floor reference resistor connected across said source, movable contacting means for said resistor, means responsive to a voltage difference between said slider and contacting means for moving said contacting means, means responsive to the initiation of the starting of the car for causing a voltage difference between said slider and contacting means for advancing said contacting means with respect to said slider, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call registering means for each floor, means actuated by said contacting means for picking up and then cancelling calls which are registered, means responsive to the picking up of a call for stopping movement of said contacting means, and retardation control means controlled by continued movement of said slider after stopping of said contacting means for controlling the slowing down and stopping of the car.

6. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car, a floor reference resistor connected across said source, movable contacting means for said resistor, means responsive to a voltage difference between said slider and contacting means for moving said contacting means, means responsive to the initiation of the starting of the car for causing a voltage difference between said slider and contacting means for advancing said contacting means with respect to said slider, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call registering means for each floor, means actuated by said contacting means for picking up and then cancelling calls which are registered, means responsive to the picking up of a call for stopping movement of said contacting means, a hall lantern at each of said floors; and means controlled by said means for stopping movement of said contacting means for causing lighting of the hall lantern for the floor for which the call is picked up.

7. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car to register car position, a resistor connected across said source, said resistor having tapped points representing said floors to provide sections of ohmic values corresponding to the heights of said floors, contacting means adapted to engage said tapped points when the car is stopped at the respective floors for which such points are provided, means responsive to a voltage difference between said slider and contacting means for moving said contacting means, means responsive to the initiation of the starting of the car for applying a biasing voltage between said slider and contacting means for advancing said contacting means with respect to said slider an amount determined by the value of said biasing voltage, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call registering means for each floor, and call pick-up means actuated by said contacting means for picking up registered calls said advance distance from the floors for which the calls are registered.

8. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, an alternating current voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car to register car position, a resistor connected across said source, said resistor having tapped points representing said floors to provide sections of ohmic values corresponding to the heights of said floors, contacting means adapted to engage said tapped points when the car is stopped at the respective floors for which such points are provided, means responsive to a voltage diiference be tween said slider and contacting means for moving said contacting means in a direction determined by the phase of said voltage diiference, means responsive to the initiation of the starting of the car for applying between said slider and contacting means a biasing voltage of a phase for advancing said contacting means with respect to said slider in the direction in which the car is to move and an amount determined by the value of said biasing voltage, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call 'registering means for each floor, call pick-up means actuated by said contacting means for picking up registered calls during said advance or during movement of said contacting means in advanced condition, and means responsive to the picking up of a call for stopping said contacting means moving means with said contacting means in engagement with the tapped point for the floor for which the call is picked up.

9. In a control system for an elevator car serving a plurality of fioors, a motor for raising and lowering the car, an alternating current voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car to register car position, a resistor connected across said source, said resistor having tapped points representing said floors to provide sections of ohmic values corresponding to the heights of said floors, contacting means adapted to engage said tapped points when the car is stopped at the respective floors for which such points are provided, means responsive to a voltage difference between said slider and contacting means for moving said contacting means in a direction determined by the phase of said voltage diiference, means responsive to the initiation of the starting of the car for applying between said slider and contacting means a biasing voltage of a phase for advancing said contacting means with respect to said slider in the direction in which the car is to move and an amount determined by the value of said biasing voltage, thus causing said contacting means to move in advanced relation to said slider during movement of the car, call registering means for each floor, call pick-up means actuated by said contacting means for picking up registered calls during said advance or during movement of said contacting means in advanced condition, means responsive to the picking up of a call for stopping said contacting means moving means with said contacting means in engagement with the tapped point for the floor for which the call is picked up, the movement of said slider taking up said advance as the car comes to said floor, and retardation control means controlled by the taking up of plying a voltage to the diagonal of the the advance for controlling the retardation of said motor to slow down and bring the car to a stop at said floor.

10. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a first resistor for providing car position reference, a second resistor for providing floor position reference, a third resistor for providing car position reference, movable contacting means for each resistor, said first and second resistors being connected in bridge relationship across said source and said first and third resistors being connected in bridge relationship across said source, means for moving the contacting means for said first resistor in accordance with movement of the car, means responsive to a voltage difference across the diagonal of each bridge for moving said contacting means for the other resistor of that bridge, means for apbridge formed by the first and second resistors to cause said contacting means for said second resistor to advance a fixed amount with respect to said contacting means for said first resistor incident to the starting of the car so as to cause movement of said contacting means for said second resistor in said advanced position with respect to said contacting means for said first resistor during movement of the car whereas said contacting means for said third resistor is moved in synchronism with said contacting means for said first resistor.

11. In a control system for an elevator car serving a plurality of floors, a motor for raising and lowering the car, a voltage source, a potentiometer connected across said source, said potentiometer having a slider actuated by the elevator car in accordance with the movement of the car, a first floor reference resistor connected across said source, a second floor reference resistor connected across said source, movable contacting means for each of said first and second resistors, means responsive to a voltage difference between said slider and first resistor contacting means for moving said first resistor contacting means, means responsive to a voltage difierence between said first resistor contacting means and said second resistor contacting means 'for moving said second resistor contacting means, thus tying them together, means responsive to the initiation of the starting of the car for causing a voltage difference between said slider and first resistor contacting means for advancing said first resistor contacting means and thus also said second resistor contacting means with respect to said slider, causing both said contacting means to move in advanced relation to said slider during movement of the car, landing call registering means for each floor, landing call pick-up means actuated by said first resistor contacting means for picking up landing calls which are registered, car call registering means for each floor, car call pick-up means actuated by said second resistor contacting means for picking up car calls which are registered, means responsive to the picking up of a call for stopping movement of both said contacting means, and means controlled by continued movement of said slider after stopping of said contacting means for slowing down and stopping the car at the floor for which the call has been picked up.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,304 Graham Aug. 14, 1934