US1930900A - Elevator control apparatus - Google Patents

Description

Oct. 17,1933. D. L. LINDQUIST ET AL 1,930,900

Bmvuoa common APPARATUS Filed Feb. 29, 1932 2 Sheets-Sheet 1 Oct. 17', 1933. 0.1.. LINDQUIST Err AL ,9 0

ELEVATOR CONTROL API ARATUS V Filed Fb. 29,3932 2 Sheets-Sheet 2- UNITED STATES PATENT OFFICE ELEVATOR CONTROL APPARATUS David Leonard Lindquist, Hartsdale, and Jacob Daniel Lewis, Yonkers, N. Y., assignors to Otis Elevator Company, New York, poration of New Jersey N. Y., a cor- Application February 29, 1932. Serial No. 595,838

28 Claims.

, This invention relates to elevators and especially to a drive for apparatus actuated in accordance with the movement of elevator cars.

It is frequently desirable in an elevator system to have a mechanical element actuated in accordance with the vertical movement of the elevator i car in the hatchway. Such a mechanical element may be made to operate various mechanisms associated with, or incorporated in, the elevator system'to accomplish a variety of functions. To the end that such mechanisms may be operated accurately with respect to the position of the elevator car in the hatchway, it is desirable that the mechanical element accurately reproduce its prescribed movements notwithstanding such variable factors as stretch of the hoisting cables, creepage and slippage of the hoisting cables around the hoisting sheave, location-of the elevator car in the hatchway, speed of movement of the elevator car, and direction of movement of the elevator car.

The object. of this invention is to provide a positive and accurate drive for an element movable in a prescribed path, which movement shall be in accordance with the movement of the elevator car. n

One feature of the invention resides in providing a single tape extending between the elevator car and a'point, either above the upperv the lower limit of travel of the elevator car, with provision that such tape is wound up on a reel as the car imoves in onedirection, and unwound from such reel as the car moves in the other direction. The rotation of the reel is thus in accordance with the movement of the elevator car, so that the shaft of such'reel may drive the device to be actuated in accordance with the movement of the elevator car.

Another feature resides in providing an electric drive for the tape reel which exerts a substantially constant torque upon the reel regardless ot the speed or direction of movement of the elevator car.

A third feature resides in controlling the power to the electricmotor of the electric drive in such manner that the torque exerted thereby 'onthe tape reel to which such motor is connected, is substantially constant.

A fourth feature is the use of a direct current separately-excited motor connected to the tape reel and having its armature connectedto a constant voltage source of current and a variable voltage source of current in series, the latter varying in value in accordance with the car speed and in polarity in accordance with direction of car movement.

A fifth feature is the utilization of the voltage across the armature terminals of an elevator motor in a Ward-Leonard system of control as the source of variable volt'ageto be combined with the constant voltage in the control of the tape'reel motor.

A sixth feature resides in providing that the movable element which is actuated'in accordance with the movement of the elevator car travels in a vertical path oppositely to the movement of the elevator car. Thus, when the elevator car is at its upper limit of movement, the movable element is at its lower limit of movement, and vice versa. When the tape reel motor actuates a movable element travelling in such manner, the movable element acts as a counterweight for the tape.

A seventh feature is the provision of a brake which is applied to prevent the tape unwinding when the tape reel motor is deenergized.

' An eighth feature is the provision of mechanisms, actuated upon the breaking of the tape or upon development of any undue slack therein, to effect the stopping of the elevator car, the deenergization of the tape reel motor and the application of the braking means to the tape driving equipment.

Other features will become apparent from the specification taken in consideration with the accompanying drawings and the subjoined claims.

The invention will be described as driving a scalar reproduction of the elevator car and hatchway, one form of which is the so-called selector or selector machine embodying an element moving in simulation of the movement of the elevator car in the hatchway. The uses to which such elevator selector machine maybe put are many. At the present time elevator selector machines are commonly used in effecting automatic control of elevator cars, such as automatically slowing down and stopping an elevator car at a floor at which a passenger in the car desires to be let oil, or. from which a prospective passenger desires to be taken on. Elevator selector machines are. also commonly used in automatically levelling an elevator car with a floor at which it is making a stop and in automatically maintaining the elevator car level with such floor while the car remains there, and in automatically operating the numerous signals and indicating equipment of one form or anwith car movement, independent of the use of such machine or device, no attempt is made herein to disclose or describe the manner in which such machine or device may actuate or control the elevator car, the elevator signals, or any other device associated with the elevator installation.

In the drawings:

Figure 1 is a schematic view of a portion of an elevator system embodying the invention;

Figure 2 is a schematic wiring diagram illustrating electrical connections for the embodiment of the invention shown in Figure 1; and

Figure 3 is a schematic Wiring diagram of an elevator system illustrating a form of the invention as applied to an elevator installation employing a Ward-Leonard type of control.

Referring to Figure 1 of the drawings, the elevator car designated 57 is raised and lowered in the elevator hatchway by means of hoisting roping 48 passing over a sheave 46 driven by an electric motor 23. The elevator hoisting motor 23 is provided with a customary electromagnetically releasable brake 60. Mounted upon the sheave-bearing stand is a tachometer generator 36 with its armature arranged to be driven in accordance with the speed of rotation of'the elevator hoisting sheave 46. This may be conveniently effected by coupling the armature of the tachometer generator to the extended shaft of the hoisting motor 23. The function of the tachometer generator as used in this: invention will be explained later.

A flexible cable or tape is secured at one end to the top of the elevator car and at the other end to a reel 47 mounted upon a shaft 44 located above the upper limit of travel of the elevator car. The means securing the tape to the car comprises a clamp 52 gripping the end of the tape, an arm 51 pivoted upon a bracket secured to the elevator car, and suitable connections securing the clamp 52 to the end 53 of arm 51. The other end of arm 51 is cam shaped to cooperate with an actuating roller of a mechanically operated switch 54. The end 53 of arm 51 is weighted. This results in biasing the arm 51 into a position in which the contacts of switch 54 (for conven ience termed the slack tape switch) are sepa rated, due to the engagement of the cammed end of arm 51 with the actuating roller of the slack tape switch 54. Normal tension in the tape, however, overcomes this bias and causes the cammed end of arm 51 to engage a stop formed on bracket 55, in which position the contacts of the slack tape switch 54 are in engagement. As a result of this construction, should any undue slack develop in the tape 50, or should the tape break, the weight-biased end 53 of arm '51 falls. and thus causes the separation of contacts of the slack tape switch 54. 4

The tape 50 is adapted to be spirally coiled in a circumferential groove on the reel 47. Shaft 44, to which reel 47 is secured, is an extension of the shaft of an electric motor 38. Operating upon the other extension of this shaft 44 is a'spring applied, electrically releasable brake 31. The motor 38 and the brake 31 are termed, respectively, the tape motor" and the tape motor brake". The connections for the tape motor and the tape motor brake are such, as is described later in conjunction with Figure 2, that when the tape motor brake is released, the tape motor issoastowindupthetapeonthe reel, thereby taking up all slack in the tape and putting it under tension.' When the tape motor is sac 1 the tape motor brake becomes effective. The action of the tape motor brake, when applied, prevents the tape from unwinding oil the reel 47 due to the weight of such tape as depends therefrom. Before the elevator car is' moved, the tape motor brake is released and the tape motor energized so as to establish an operating tension in the tape. Thereafter, when the car moves downwardly, the tape, in winding oil the reel, causes the rotation of the reel in the direction opposite to that in which the tape motor tends to rotate it. On the other hand, when the car moves upwardly, the reel is able to rotate in the direction in which it is urged by the tape motor, and as a result the tape is wound up on the reel as fast as the up movement of the car permits the motor to rotate the reel. Shaft 44, upon which the tape reel is mounted, is therefore actuated in accordance with the movement of the elevator car.

As illustrated in Figure 1, the rotation of shaft 44 in accordance with the movement of the elevator car is utilized to actuate a selector machine. Any type of selector machine or other device may be operated from shaft 44. In the event a selector machine is to be actuated by shaft 44, the selector mach'ne 78 diagrammatically illustrated in Figure 1 is advantageously employed. There is first a gear reduction 72 by which the movement of shaft 44 is suitably reduced. Upon the shaft 69 of the gear reduction 72 is mounted a 1 reel 66. To reel 66 is secured one end of a flexible transmission member, such as a chain or tape. Selector chain 64 passes over guide rollers 65 and is connected at its other end to a vertically movable selector crosshead 62 suitably guided by rods 63. When the reel 66 is rotated to wind up thereon the chain 64, the selector crosshead 62 is raised, while when the reel 66 is rotated to unwind therefrom the chain 64, the selector crosshead 62 moves downwardly under the influence of its own weight. Preferably, the arrangement of the equipment between ,the tape 50 and the selector chain 64 is such that when the eleva. tor car is travelling downwardly, the selector crosshead 62 is travelling upwardly, and vice versa. The movement of selector crosshead 62 is thus opposite to the movement of elevator car 57, so that when the elevator car is at its upper limit of travel the selector crosshead 62 is at its lower liinit of movement, and vice versa. Such an arrangement results in an inverted selector machine, but is of advantage due to the fact that the weight of the selector crosshead 62 acts as a counterweight for the tape 50.

The selector crosshead 62 may be provided with one or more brushes or sets of brushes, such as 67 and 68, engaging respectively with sets of stationary contacts, such as 70 and 71.

Elevator car 57 may be controlled in any desired manner. As suggestive of one manner by which the car may be controlled, there is shown mounted within the car a control panel 73 having a plurality of buttons 74, one-for each floor served by the elevator car. By suitablecontrolling equipment, the car, upon operation of a button 74 by 111) a passenger in the car, may be caused to start up. and move in the di:ection of the floor represented by the button operated, and then caused to slow down and stop at such floor. A selector machine actuated in accordance with car movement, as is the selector machine 78, is very commonly an adjunct in such controlling equipment for the'elevator car.

Switches 75 and 76, shown on the operating panel 73, represent respectively the safety stop- 5 ping switch and the key switch; the former of which, upon operation, stopsjthe elevator car wherever it may be, and the latter of which is a switch by which the elevator installation may be made available'for use or shut down. I

In Figure 2 of the drawings, there is shown a schematic wiring diagram for the electric equipment illustrated in Figure 1. For simplicity, no

,attempt is made to show the manner by which the elevator hoisting motor.23, having an armature 21 and a field 24, is controlled.

According to the arrangement of the control and power circuits illustrated in Figure 2 for effecting control of the tape motor 38 in accordance with thprinciples of this invention, the armature 40 of the tape motor 38 and the armature 3'7 of thetachometer generator 36 are connected in series across the direct current, constant potential supply line controlled by line switch 20. d To limit the current through the armatures 37 and 40 when the elevator car is stationary, resistance 42 is provided, this resistance preferably being adjustable. A pair of contacts S41 of an electromagnetic relay S45 controls the energization of the armatures 3'7 and 40. The actuating coil of relay S45 is connected across the supply terminals through the intermediary of the slack tape switch contacts 54. As a result, when the contacts 54 of the slack tape switch are in engagement and normal full voltage is furnished from the supply mains, relay S45 operates to close contacts S41, S30 and S22.

The engagement of contacts S41 completes the circuit for the. tape motor armature 40, as explained above.- The separately excited field 32 of the tachometer generator and the separately excited field 34 of the tape motor become energized when the line switch 20 was thrown to connect the supply line tothe tape driving equipment. The flow of current through the armature 40 of the tape motor, whenthe tape motor field 34 is energized, thus results in the tape motor exerting torque upon the shaft 44. -The polarity of the current through the tape motor armature 40, with ,respect to the polarity of the current through the tape motor field 34, is such that the torque exerted by the tape motor upon the armature 44 tends to rotate the reel 47 so as to wind up thereon the tape 50. v I

The closing of contacts S30, which occurred at the same time thatpontacts S41 closed to energize the tape motor armature, completes a circuit for the brake coil 27 of the tape motor brake 31. The tape motor brake is thereupon released. The torque exerted by the tape motor 38 is thus effective to rotate the tape reel 47 so as to render the tape 50 taut and to maintain it under tension. The elevator car, it is assumed, is stationary.

Adjustable resistances 33 and 35 are preferably employed for controlling the field current in the tachometer generator andin the tape motor, respectively. It is also preferred that the tape motor brake be provided with a pair of contacts 25 which are caused to separate when the tapemotor brake is released- Contacts 25, when separated, insert in series with the brake coil 2'7 an adjustable resistance 26. It is also preferred to provide a discharge resistance 28 for the tape motor brake coil 2'1.

It will be recalled that, upon the engagement of contacts S41 and S30, there was also caused the engagement of contacts S22. Contacts S22 are preferably placedin the control system for the elevator hoisting motor 23 in such a manner that the hoistingv motor 23 can be operated to move the elevator car only when contacts S22 are in engagement. This isconveniently effected by inserting contacts S22 in the same circuit with such safety devices as the emergency stopping switch, the over-speed governor switch, and the potential switch. Such circuit is commonly referred to as the potential switchcircuit. For simplicity, the details of this circuit are no shown in Figure 2.

Let it now be assumed that the elevator car 57 is caused to move upwardly, and the counterweight 56 downwardly. In this direction of movement of the elevator car, the tape motor 38 winds up tape 50 on the reel 47. The speed of rotation of the armature 40 of the tape motor is thus in accordance with the speed with which the elevator car movesupwardly. The rotation of armature 40 of the tape motor across the flux produced by the tape motor field 34 causes the generation in the armature 40 of the tape motor an induced voltage proportionalto the speed of rotation thereof. When the elevator car is moving upwardly, the tape motor 38 acts as a motor so that as a consequence the polarity of the voltage induced in the tape motor armature 40 is in bucking relation to the polarity of the voltage impressed across the tape motor armature terminals. The voltage induced in the tape motor armature 40 is thus, in polarity, in opposing relation to the supply line and, in magnitude, variable s generator 36. The direction of the flow of current through the tachometer generator field 32, with respect to the direction of the flow of .current through the tachometer generator armature 37, is made such that when the elevator car is moving upwardly, the voltage generated by the tachometer generator is in an assisting or additive relation to the constant potential source of supply. Specifically, the connections are made in such a manner that when the. elevator car is moving upwardly, the voltage induced in the tachometer generator armature 37 is plus at the left hand brush and minus at the right hand brush, as the tachometer generator connections are viewed in Figure 2.

The magnitude of the voltage generated in the tachometer generator is, by appropriate-design of the mechanical and electrical parts and by appropriate adjustment of the field resistances 33 and 35, made to equal, or substantially equal,

the magnitude of the induced voltage generated in the tape motor armature 40, for all speeds of the elevator car from zeroto full speed. This is possible since the voltage generated by the tachometer generator and the induced voltage generated in the tape motor armature are both proportional to the speed of the elevator car. The induced voltage in the tape motor armature caused by the rotationthereof, is thus compensated for by introducing in the tape motor armature circuit a voltage opposite in polarity to the tape motor induced voltage, and equal in magnitude thereto, for all speeds of the elevator car in the up direction. The current through the tape motor armature is thus determined by the potential 7 A similar compensation exists when the elevator car 57 moves in the down direction. The polarity of the voltage generated by the tachometer generator when the car moves in the down direction is opposite to its polarity when the car is moving in the up direction; However, the magnitude of the voltage is proportional to car speed, as before. When the car is moving in the down direction, the car drives the tape motor in a direction opposite to that in which it rotates when the car moves in the up direction. Thus, the voltage induced by such reverse rotation of the tape motor armature is, in polarity, opposite to that when the car is moving in the up direction. In magnitude, however, it is in accordance with car speed similarly as when the car is travelling in the up direction. Since, when the elevator car moves downwardly, the polarity of the voltage generated by the tachometer generator and the polarity of the induced voltage generated in the tape motor armature are both reversed from that when the elevator car is moving in the up direction, these two voltages buck each other when'the car is moving downwardly as well as when the car is moving upwardly. Since the magnitude of the voltage generated in the tachometer generator and the magnitude of the induced voltage generated in the tape motor armature are both proportional to speed, regardless of the direction of car movement, these two voltages substantially completely cancel each other for all speeds of the elevator car from zero to full speed, regardless of whether the car moves in the up direction or in the down direction.

The current through the tape motor armature is thus determined by the potential of the supply line for all speeds of the elevator car, regardless of the direction in which the car is moving. As the potential of the supply line is constant, the current through the tape motor armature is constant. Constant torque is therefore exerted by the tape motor 38, for both directions of travel and for all'car speeds. I

The cancellation of the voltage induced in the armature of the tape motor by the voltage generated by the tachometer generator, may be illustrated mathematically as follows, using the following symbols:

Vs=Voltage of supply line,

VTG=Voltage generated by tachometer generator,

Vm=Voltage induced in tape motor armature,

I=Current through tape motor armature and tachometer generator armature,

R=Resistance in the tape motor armature circuit (includes current limiting resistance 42) When the elevator car is stationary,

When the elevator car is moving upwardly,

sru+ Ta By design and adjustment, the magnitude of. V'ra is made equal, or substantiaolly so, to the magnitude of Vm, for all car speeds from zero to full speed. Y Therefore, by force of (3), Equation (2)becomes,

When the elevator car is moving downwardly,

The design and adjustment described in (3) still obtains when the car is moving in the opposite direction.

Therefore, by force of (3), Equation (5) becomes,

Inasmuch as Vs is a constant potential source,

is a constant value. As a consequence, the vale of I, the current through the tape motor armature, is a constant value regardless of the speed or direction of movement of the elevator car. The torque exerted by the tape motor 38, which varies in accordance with the magnitude of thecurrent through the tape motor armature, is thus constant, or substantially so, regardless of the speed or direction of movement of the elevator car.

In the event, for any reason, undue slack develops in tape 50, the weight-biased end of arm 51 falls sufficiently to cause the separation of contacts 54 of the slack tape switch. The separration of contacts 54 results in the deenergization of actuating coil S45 so that contacts S22, S30 and S41 immediately separate. The separation of contacts S41 and S30 effects the deenergization of the tape motor and the tape motor brake coil, so that as a result the tape motor ceases deliver-' ing torque to the tape reel and the tape motor brake is applied. Separation of contacts S22 causes the stopping of the car, if it is in motion,

"and prevents the car from being operated until the trouble with the tape driving equipment is located and remedied.

Inthe event that there is a substantial reduction in the voltage of the supply mains, the switch S45 drops out with the same consequences as explained above. If desired, the value of the resistance 26 may be adjusted so that the tape motor brake is applied upon an appreciable reduction in the voltage of the supply mains independently of the dropping out of switch S45.

In Figure 3 of the drawings there is shown a schematic wiring diagram of an elevator system with a Ward-Leonard system of control in which is incorporated a single tape drive in accordance with the principles of this invention.

In this figure, the coils and contacts of the electromagnetic switches are separated in the interest of simplification of .circuits. For convenience in understanding the diagram, however, each coil is associated with the contacts which it actuates by means of a dot-and-dash line. In addition, rotating parts mounted on the same shaft are connected by a dot-and-dash line.

The various electromagnetic switches em- .ployed in the control system chosen to illustrate the principle of the invention are designated ,as a whole as follows: A-Up direction switch, B Down direction switch, 'CPotential switch, I) Accelerating switch, H-Field and brake switch, K-Elevator motor counterelectromotive force switch, L-Line switch, LL--Auxiliary line switch, OL-Overload switch, M--Running .switch, and TTape motor switch.

Throughout the description which follows, these letters are applied as prefixes of the reter- 93,-to phase III.

ence numerals for the parts of the above designated switches. Thus, for example, L82 indicates that the coil referred to ,is the actuating coil of the line switch, while A137 indicates contacts of the up direction switch. In the case of the numerals employed in the control system of Figure 3, the lowest number appears in the upper left-hand corner of the figure, with the succeeding numbers following in numerical sequence, from left to right, downwardly of the sheet of drawings. The arrangement of the numbers in this sequence facilitates the ready location of anyv element referred to in the description. Electromagnetic switches are shown in their deenergized positions.

The control system illustrated in Figure 3 for the elevator car 187 is of the Ward-Leonard type, in which 81 is the motor and 136 the generator of the motor-generator set, 101 is the exciter driven from shaft 124 of the motor-generator set and 156 is the elevator hoisting motor. The elevator brake is designated 128, and the hoisting sheave is designated 177, both being mounted on the same shaft, 148, to which is secured the armature 157 of the elevator hoisting motor 156. The tape reel, the tape motor brake, and the tape motor are designated 178, 161 and 162, respectively, and are all connected by shaft 168.

Shaft 168 may actuate any device, including a selector machine, the movable element of which is to have a motion in accordance with the move-. 'ment of elevator car 187.

In order to simplify the description of this embodiment of the invention, the invention is shown in Figure 3 as applied to an elevator system in which the starting and stopping of the elevator car 187 is effected by an operator in the car through the medium of a car switch 113. It is to be understood, however, that the invention as applied to a Ward-Leonard type of controlin the manner as shown in Figure 3, is applicable to any type of elevator system, in-. cluding those in which the starting and/or stopping of the elevator car is effected automatically.

As shown in Figure 3, the elevator system is completely shut down, that is, the motor-generator set is not running, the elevator car is stationary, and the elevator brake and the tape motor brake are applied. The first step to be but for the present .this is of no effect inasmuch i as contacts M94 are separated. Theengagement of bridge 92 with contacts and 93 completes a circuit for actuating coil LL87 of ,the auxiliary line switch, the circuit being traceable from phase 11, through actuating coil LL87, by way of contacts OL88, contact 90, bridge 92 and contact The resulting operation of the auxiliary line switch LL causes the engagement of contacts LL83 and 'LL103. The engagement of contacts LL83 completes a circuit for the actuating coil L82 of the line switch. The line switch L thereupon operates to cause the engagement 'of contacts L80, L86, L98 and L170, and the separation of contacts L160. The engagement of the first three of these contacts of the line switch connects the stator windings 85 of the alternating current motor 81 to the main power lines I, II, and III. The motor 81, being thus energized, effects rotation of its armature 84, and as a consequence drives the armature 102 of the exciter 101 and the armature 142 of the generator 136. The generator 136 may bev neglected at this phase of the description, due to the fact that, as the generator is provided with no field at this time, the generator is ineffective.

The rotation of armature 102 of the exciter 101,

the exciter being provided with a shunt field 100, results in the building up of exciter voltage until,

when the motor 81 of the motor-generator set attains full speed, the exciter voltage reaches its normal value.

When the exciter voltage has reached operating value, the actuating coil M104 of the running switch (which is connected across the terminals of the exciter by way of contacts LL103, these contacts having been closed as previously described) causes the operation of the running switch M, and the engagement of contacts M94. The engagement of contacts M94 completes an additional circuit for the actuating coil of the auxiliary line switch, this circuit being traceable from phase II, through coil LL87, by Way of contacts OL88, contacts M94, elongated contact 95, bridge 96, elongated contact 97, to phase III. The key switch 91 may now be released, and, upon its return to its initial position (that illustrated in Figure 2), the actuating coil LL87 is maintained energized due to the fact that bridge 96 continues in engagement with elongated contacts and 97 when the key switch 91 is in its initial position. The motor 81 of the motor-generator set is therefore continued energized so long as the exciter voltage does not fall below a predetermined value. If, for any reason, the exciter voltage should fall below such predetermined value, the exciter voltage becomes insuificient to maintain the running switch -M operative, whereupon, as a consequence of the resulting separation of contacts M94, the motorgeneratorset ,is shut down. The motor-generator set may beshut down intentionally by turning key switch 91 counter-clockwise from its normal position so as "to cause bridge 96 to become disengaged and 97.

Assuming that the motor-generator set is in operation, and that it continues in operation at its normal speed, the resulting voltage of the exciter 101 causes the energization of both the from elongated contacts 95 g elevator motor field 167 and the separately ex-' cited tape motor field 163. At the moment, the

energizations of these fields is of no effect. The existence of full exciter voltage also causes the operation of the tape motor switch T, provided the slack tape switch contacts 184'are in engagement, due to the .energization of actuating coil T176. The operation of the tape motor switch T results in the engagement of contacts T154 and T173. The engagement of contacts T154 completes a circuit for the armature 153 of the tape motor and for the brake release coil 152 of the tape motor brake 161. This circuit may be traced from thenegative terminal of the exciter 101, by way of resistance 133, armature 157- of the elevator motor 156, resistance 1,50, brake release coil 152 (since contacts L160 are separated, switch L being'in operated position), armature 153 of the tape motor, contacts T154, actuating coil OL155 of the overload switch, to the positive terminal of the exciter. The tape motor brake 161 is thereupon released, and, since the separately excited field 163 of the tape motor is already energized, as noted above, torque is developed by the tape motor 162 tending to rotate the tape reel 178 so as to wind up the tape thereon. Operating tension in the tape 181 is accordingly obtained.

The engagement of contacts T173 of the tape motor switch completes a circuit for the actuating coil C171 of the potential switch C. This circuit. may betraced from the negative terinal of the exciter 101, by way of contacts 184 of the slack tape switch, contacts L170 (which are in engagement when the motor 81 of the motor-generator set is operating, as previously described), actuating coil C171, the several terminal limit switches generally designated 172, contacts T173, elevator over-speed governor contacts 174, and emergency stop button 175, to the positive terminal of the exciter. The resulting operation of the potential switch C causes the engagement of contacts C105 and C106. This effects the connection of the control circuits for the elevator car to the terminals of the exciter.

101. The control circuits are now operative to control the movements of the elevator car.

Let it now be assumed that the car switch 113 is thrown clockwise, as viewed in Figure 3, so as to cause the conducting bridge 117 to connect contact 118 with contacts 112 and 111. In the event the car door and hatchway doors are closed so that the car door interlock contacts 122 and the hatchway door interlock contacts, represented as one contact 123, are in engagement, the elevator car 187 is caused to move upwardly and the counterweight 186 to move downwardly.

The starting of the car in the up direction and bringing it up to full speed is effected in the following manner: Engagement of bridge 117 with contacts 112 and 118 completes a circuit for the actuating coil A108 of the up direction switch and for the actuating coil H107 of the field and brake switch. This circuit may be traced from the negative terminal of the exciter 101, by way of contacts C105, actuating coil H107, actuating coil A108, electric interlock contacts B110, contact 112, bridge 117, contact 118, door interlock contacts 122 and 123, and contacts C106, to the positive terminal of the exciter 101.

The resulting operation of the field and brake switch H causes the engagement of contacts H132 and the separation of contacts H134 and H151. .The engagement of contacts H132 completes the circuit for the brake release coil 130 of the elevator brake 128. The separation of contacts H134 and H151 relieve the generator field 143 of the suicide connection. The resulting operation or the up direction switch A causes the separation of contacts A115 and the engagement of contacts A137 and A145. The separation of contacts A115 acts as an electric interlock to prevent the operation of the down di- 'rection switch B while the up direction switch A is in operative position. The engagement of contacts A137 and A145 completes a circuit for the energization of the generator field 143 from the exciter 101. This circuit may be traced from the negative terminal'ol? the exciter 101, by way of contacts C105, contacts A137, generator field 143, contacts A145, generator field resistances 140 and 141, contacts C106, to the positive terminal of the exciter. The generator field thus builds up and causes the production of voltage across the generator armature terminals. This voltage causes the flow of current in the loop circuit including the generator armature V142, elevator motor armature 157 and the generator series field 147, Since the elevator motorfield 167 is energized, the fiow of current through the elevator motor armature 157 results in causing the rotation thereof, and thus of the elevator hoisting sheave 177. The connections for the various equipment just described are such that, when generator field 143 is energized due to the operation of the up direction switch A, the elevator motor rotates in such a direction as to raise the elevator car 187. This is efiected by means of the hoisting roping 180 passing over the sheave 177.

The movement of bridge 117 of the car switch 113 so as to complete the circuit between contacts 111 and 118 causes the energization of the actuating coil D127 of the accelerating switch D. After an appropriate short time interval, the contacts D135 are caused to engage so as to shortcircuit resistance section 140. The current in the generator field 143 is thus increased, which thereby increases the voltage generated by the generator 136. The speed of rotation of the elevator motor 156, and thus the speed with which the car 187 is raised, is thereby increased. Additional accelerating switches may be provided if desired.

It is preferred that when the elevator motor brake 128 is released, a pair of contacts 125 is caused to separate so as to insert a cooling resistance 126 in series with the brake release coil 130. It is also preferred that the brake release coil be provided with a discharge resistance 131.

As the elevator car is started in the up direction and brought to full speed, the voltage across the terminals of the elevator motor armature 157 increases in magnitude in accordance with the speed of the elevator car. At a fairly low value of this voltage, the actuating coil K166 of the elevator motor counter-electromotive force switch K is energized sufficiently to cause the separation of contacts K158. The separa tion of contacts K158 is of no effect at this moment, other than to insert an additional break in the by-pass circuit around the actuating coil 1-52 of the tape motor brake. The design and adjustment of the elevator motor counter-electromotive force switch K is such that it is maintained in operated position when the voltage across the elevator motor armature is above a certain small value, during which time the elevator motor armature is rotating above a very slow speed.

.As the car ascends, the tape motor 162 causes the rotation of reel 178 to wind up the tape' 181 thereon. The rotation of the tape motor armature 153 across the flux produced by the tape motor field 163 causes an induced voltage to be generated in the tape motor armature. The magnitude of this voltage is substantially proportional to the speed of the elevator car, while its polarity is opposite to that of the voltage impressed across the tape motor armature.

Such induced voltage generated in the tape motor armature is compensated for, according to the arrangement illustrated in Figure 3, by the voltage across the elevator motor armature 157. The voltage across the elevator motor armature 157 varies'substantially in accordance with the speed of the elevator car, as explained above. The polarity of the voltage across the elevator motor armature determines the direction in which the elevator motor armature rotates, so that as a consequence the polarity of this voltage varies in accordance with the direction of movement of the elevator car. The circuit through the tape motor armature 153 and the elevator motor ar- 5 mature 157 is opposite to the polarity of the induced voltage generated in the tape motor armature 153. By appropriate design of the component parts, both mechanical and electrical, of

the tape driving equipment, and by adjustment of the resistances 133, 150 and 165, the induced voltage generated'in the tape motor armature 153 can be made to substantially equal in magnitude the voltage impressed across the elevator motor armature 157 for all speeds of the elevator car. The polarity of the voltage impressed across the elevator motor armature 157 being opposite to the polarity of the induced .voltage generated in the tapemotor armature 153 when the car is moving in the up direction, and the magnitude of these two voltages being substantially equal for all speeds, the current through the tape motor armature 153 is thus determined by the potential across the armature terminals of the exciter 101. This being constant while the motor generator set is in operation, the current through the tape motor armature 153 is substantially constant for all speeds of the car in the up direction.

If it be assumed that, instead of the car switch 113 having been moved to operate the car in the up direction, it was moved in the opposite direction so as to operate the car in the down direction, a situation analogous to that described above exists. The engagement of bridge 117 with contacts 120 and 121 completes the circuit for the actuating coil H107 of the field and brake switch and for the actuating coil B116 of the down direction switch. The elevator brake 128 is released similarly as before, and the generator field 143 is. energized. In this instance, however, the 'gen- 40' erator field 143 is energized as a result of the engagement of contacts B138 and B146,'which cause the energization of the generator fieldin the direction opposite to that when the up direction switch A is operated. The resulting voltage of the generator 136 is thus opposite inpolarity to that when the car switch is actuated for the up direction. As a consequence, the elevator motor armature rotates in the opposite direction, thereby lowering the elevator car 187. The engagement of bridge 117 with contacts 120 and 114 causes the operation of accelerating switch D in a manner similar as before, with the result that the car is brought to full speed in the down direction.

When the elevator car moves downwardly, the

tape motor armature is driven by the tape 181 in which it has when the car is travelling in the up direction. It is to be noted, however, that, when the car is travelling in the down direction, the polarity of the voltage across the elevator motor armature 157 and the polarity of the induced voltage generated in the tape motor armature 153 are both opposite to that which exists when the car is moving in the up direction. It is also to be noted that the magnitude of these two voltages is not substantially affected by a change in the 0 direction of car movement.

As a consequence, the induced voltage generated in tape motorarmature 153.is substantially compensated for by the introduction into the tape motor armature circuit of the voltage across the elevator motor armature 157, both when the car is moving in the down direction as well as when it is moving in the up direction, and substantially independently of the car speed. The current through the tape motor armature 153 is thus determined by the magnitude of the voltage at the armature terminals of the exciter 101. As this exciter voltageis substantially constant when the motor-generator set is running, the magnitude of the current throiigh the tape motor armature 153 is substantially constant regardless of the speed or direction of movement of the elevator car.

The torque delivered by tape motor 162 is a function of the net effective field flux in the tape motor and the magnitude of the ecurrent through the tape motor armature. The flux is substantially constant, since it is derived from the separately excited field 163, which is energized from a constant potential'source of supply (exciter 101). The tape motor armature current is substantially constant, as explained above. v is thus substantially constant regardless of the speed or direction of movement of the elevator car 187. The tape 181 is therefore maintained under tension by the reel 178 regardless of the speed or direction of movement of the elevator car; and shaft 168 becomes an appropriate driving mechanism for accurately operating any suitable device'in accordance with the movement of the elevator car.

The centering of the car switch 113 brings the car to a normal stop from its motion in either direction of travel. The centering of the car switch breaks the circuit for the accelerating switch D, the operated direction switch-(either A or B), and the field and brake switch H. The return of the operated direction switch to its initial position disconnects the generator field 143 from the exciter 101. The generator field thus The torque delivered by the tape motor dies down, and the voltage across the elevator motor armature 157 decreases. In order to prevent an excessive self-induced, voltage in the generator field-and the consequent danger of so that the generator field, and thus the generator voltage, is brought to zero rvalue.

The dropping out of the field and brake switch H also causes the separation of contacts H132, and as these are in the circuit of the elevator brake release coil 130, the elevator brake is thereupon applied. Due tothe discharge of the brake release coil through the resistance 131, there is a small lag in the full application of the brake ,from the time that contacts H132 are separated.

When the elevator motor armature is nearlystationary, the elevator motor counter-electromotive force switch K drops out and contacts K158 reengage' Under a normal stop, such as by the car switch 113, the separation and reengagement of contacts K158 are of no effect.

During the stopping of a car, the voltage across the elevator motor armature 157 is substantially in accordance with car speed, so that the current through the tape motor armature continues to be substantially constant. When the car is fully stopped, the tape motor remains energized and the current through the tape motor armature remains unchanged.

1 When it is desired to shut down the elevator installation, key switch 91 is turned counterclockwise so as to break the circuit between contacts 95 and 97. As a consequence, auxiliary line switch LL and line switch L drop out to disconnect the motor 81 from the power mains I, II and III. Normally, the motor-generator set is not'shut down except when the elevator car is stationary at a floor. As a consequence, contacts K158 for the elevator motor counter-electromotive force switch are then in engagement. The dropping out of line switch L causes the engagementof contacts L160. A by-pass circuit is thereby established around the actuating coil 152 of the tape motor brake so that the tape motor brake is thereupon applied before the voltage of the exciter 101 falls any appreciable extent, and thus before there is any appreciable loss of torque by the tape motor 162.

It is to be noted that the dropping out of the line switch L causes the separation of contacts L170 in the potential switch circuit. As a consequence, in the event the motor-generator set "should be shut down, as by turning the key switch 91 counterclockwise, when the elevator car is in motion, the actuating coil C171 of the potential switch is thereupon deenergized and con-' tacts C105 and C106 are caused-to separate. The

"separation of contacts C105 and C106 disconnect the control equipment of the elevator car from the exciter 101 and thus cause the deenergization of the field and brake switch H, the operated direction switch A or B, the accelerating switch D, the actuating coil of the elevator motor brake 128, and the generator field 143. car is thus quickly brought .to a stop.

Under such conditions, however, the dropping the up direction when the motor-generator set is shut down, the tape motor 162 is effective to reel up the tape 181 along with the up motion of the elevator car during. the stopping thereof. When the elevator motor armature is nearly stationarigthe K switch drops out andcauses the reengagement of contacts 158. The circuit by: passing the actuating coil 152 of the tape motor brake 161 is thereupon completed so that the coil becomes ineffective and the tape motor brake is applied. Due to the natural discharge time of the brake coil, the tape motor brake becomes fully effective a short time after the contacts K158 reengage. The tape motor brake thus becomes fully effective practically simultaneously with, or shortly after, the cessation of rotation of the elevator motor armature. The application of the tape motor brake is, in this manner, delayed when its application would tend to result in the creation of slack in the tape 181.

The elevator car may also be stopped by the operation of any one of a number of safety devices, contacts controlled by which are placed in the circuit of the actuating coil C171 of the potential switch. Thus, the car may be stopped The elevator" from within the car by pressing emergency stopping button 175. The resulting dropping out of the potential switch C causes the stopping of the car similarly as described above. The motor-generator set, however, continues in operation so that as a consequence torque is maintained by the tape motor and the tape motor brake is maintained released.

In the event that any undue slackshould develop in the tape 181, the weighted end 183 of arm 182 falls and causes the cammed end of arm 182 to effect the separation of contacts 184. The separation of contacts 184 causes the deenergization of the actuating coil T176 of the tape motor switch. The consequent separation of contacts T154 deenergizes the tape motor and results in the application of the tape motor brake. The separation of contacts T173, which occurs concurrently with the separation of contacts T154, breaks the circuit for the actuating coil C171 of the potential switch and thereupon effects a potential switch stop, as described above. If desired, the potential switch circuit may be carried directly through contacts 184 of the slack tape switch, as illustrated in Figure 3, so that there is added assurance that the car will be stopped and prevented from operation in the event there is a broken tape, or there is any undue slack therein.

There is shown in dotted outline in the tape motor armature circuit a tapemotor series field 164 which may be employed if desired. This series field winding, when inserted in the circuit at the place indicated, when constructed with appropriate constants, and when adjusted in a manner to be described, is a refinement which may be utilized, if desired, to compensate for miscellaneous minor factors which may tend to cause some variations in the torque exerted by the tape motor. Among such factors'is the effect of the flow of power current from the generator 136 through the resistance of the armature 157 of the elevator motor. Although the resistance of the elevator motor armature is generally very small, such power current through the elevator motor armature, may, in some installations and under certain conditions, be of such a value that the resistance drop through the elevator motor armature resulting from the flow of such power current therein is sufliciently large in value, in proportion to the other voltages in the tape motor armature circuit, to warrant its consideration Under such conditions it may be desirable to utilize the series fieldas herein described.

The series field 164 of the tape motor is connected so that the flux resulting from the flow of tape" motor armature current through it (the current in. the tape motor armature circuit always fiows in the same direction) counteracts, or opposes, the flux established by the separately excited field 163. The resistance 165 in the tape motor field circuit is then re-adjusted to produce, as the net effective flux of the tape motor, a value of effective flux equal to the initial effective flux which was present before the series field was inserted. This adjustment is preferably made when the elevator car is stationary, although it may be made when the car is in motion under conditions where the power current is small.

It will be recalled that, when the elevator car moves upwardly, the voltage existing across the elevator motor armature-that is, the voltage introduced in the tape motor armature circuit to compensate for the induced voltage generated in the tape motor armatureis additive to the voltage of the constant potential source of supply in the tapemotor armature circuit (the voltage of the exciter 101 in Figure 3). When the voltage across the elevator motor' armature comprises, in addition to the counter-.electromotive force of the elevator motor armature, a voltage drop due to the flow of power current therethro'ugh'thait is to be reckoned with, such voltage drop due to the flow of power current through the elevator motor armature resistance is additive to the voltage of the exciter 101 and is not cancelled or corrected for by the induced voltage generated in the tape motor armature. As a consequence, the effect, when there is any worthy of consideration, of such elevator motor armature resistance drop when the car is moving upwardly, is to increase the current flowingthrough the tape motor armature above the. value of current flowing therethrough when the elevator car is stationary or when the effect of the elevator motor armature resistance drop is negligibl By the addition ofseries field 164 in bucking relation to the tape motor separately excited field 163, such increase in value of the tape motor armature current decreases the net effective flux in the tape motor. The torque exerted by the tape motor armature, being dependent upon the current passing through the armature of the tape motor and the net effective flux cut by such armature, is thus subject to two opposing tendencies; to increase, due to the increase. in the tape motor armature current, and to 'decrease, due to the decrease in the net effective fiux of the tape'motor. The actions of these two opposing tendencies practically cancel each .other, so that as a result the torque exerted by the tape motor when the elevator .car is moving in an up direction, is not eifected by the voltage drop in the elevator motor armature due to the flow of power current therethrough.

I A similar situation results when the elevator car moves downwardly, and the tape motor series field is effective in a bucking relation, as previously described. In this instance, the voltage existing across the elevator motor armaturethat is, the voltage introduced in the tape motor armature circuit to compensate for the induced voltage generated in the tape motor armatureis subtractive from the voltage of the constant potential source of supply in the tape motor armature circuit (the voltage of the exciter 101 in Figure 3). When the voltage across the elevator motor armature comprises, in addition to the counter-electromotive force of the elevator motor armature, a voltage drop due to the flow of such elevator motor armature resistance drop when the car is moving downwardly, is to decrease the current flowing through the tape motor armature below the I value of current flowing therethrough when the elevator car is stationary or when the effect of the elevator motor armature resistance drop is negligible.v

By the addition of series field 164 in bucking relation to the tape motor separately excited held 163, such decrease in value of the tape motor.

armature current increases the'net effective flux in the tape motor. The torque exerted by the armature as the source tape motor armature is-thus again subject to opposing tendencies; to decrease,'due to the decrease in the tape motor armature current, and to increase, due to the increase in the net effective flux of the tape motor. These tendencies also practically cancel each other. so that as a result the torque exerted by the tape motor, when the elevator car is moving in the down direction, is not affected by the voltage drop in the elevator motor armature due to the flow of power current therethrough.

Overload switch 0L is provided with its actuating coil OL155 in the armature circuit of the tape motor so as to shut down the installation in the event there is an excessive flow of current through the tape motor,- as might occur in the event of a ground. The overload switch controls a pair of contacts OL88in the circuit of the actuating coil for the auxiliary line switch LL, which contacts, when caused to separate by the current becoming excessive in the tape motor circuits, cause the dropping out of auxiliary line switch LL and of line switch L. Other overload switches may be employed with their actuating coils located in other .places so as to tional protection if desired.

The current limiting resistances 133 and 150,-

give addilocated in the tape motor armature circuit, may be made adjustable so depends'upon the car speed. The advantage of employing the voltage acrossthe elevator motor of this compensating voltage in the manner illustrated in Figure 3', is that one piece of rotating machinery is thereby eliminated.

When the elevator hoisting motor is an alternating current motor, a tachometer generator is preferably employed in conjunction with a direct current tape motor. The constant potential, di-. rect current source of supply for the tape motor is at hand in installations where direct current is employed for operating the control switches for the alternating current motor, or a special rectifier or motor-generator set may be employed to obtain the constant potential direct current supply.

The tape reel, tape motor and selector machine or other device actuated thereby may, if desired, be mounted on the elevator car with the free end of the tape secured to an appropriate point in the hatchway. Ordinarily, however, such an arrangement is not advantageous since dead weight is thereby added to the car and hoisting cables. Also, the tape reel, tape motor and selector machine or other device actuated thereby, may, with the aid of appropriately located guiding sheaves for the single tape, be placed at any convenient location in the installation.

A single tape drive such as herein described is of particular advantage when the tape reel, tape motor-and selector machine all are located in the penthouse a wove the upper limit '01 travel of the elevator car, as illustrated in Figure 1. With such an arrangement of parts, the: selector machine is readily accessible for care and adjustment, and the drive therefor is simple to manufacture, easy to install, accurate in operation,

hitch may ordinarily be secured to the top of the elevator car at almost any point thereon, so that as a consequence the tape reel and tape motor may be mounted in the overhead at almost any convenient point over the car where they are least in the way or where they may be most expeditiously secured. In addition, there is ordinarily a clear, unobstructed path between the top of the car and the overhead, so that there is no danger of the tape fouling with such things as the travelling cables depending in the hatchway. Furthermore, by provision of only one tape, and that extending from the overhead direct to the top of the elevator car, there is a minimum of tape installed in the hatchway. Lastly, the accuracy of selector operation by the single tape drive is insured by providing that the tapemotor exerts a substantially constant torque on the tape reel regardless of the movement of the elevator car, either in speed or in direction. This, as herein described, involves eliminating the effects of the induced voltage or counter-electromotive force generated in the tape motor armature.

Attention is directed to the fact that other methods may be employed for eliminating or compensating for the effect of the counter-electromotive force generated in the tape motor arm ature than by introducing a voltage in series with the tape motor armature thatis equal in magnitude, but opposite in polarity, to the tape motor armature counter-electromotive force. As a consequence, those claims subjoined.hereto which do not specifically involve this manner of compensation or correction are not intended to be limited to such specific manner of compensation or correction, but are intended to include generically, in combination with an electric motor single tape drive, any suitable means to compensate or correct for the tape motor armature counter-electromotive force so that the torque delivered by the tape motor armature is substantially constant for all operating speeds and for both directions of travel of the elevator car.

Attention is also directed to the fact that, in a single tape drive other methods may be employed for obtaining, as the voltage introduced in the tape motor armature circuit to compensate for the tape motor armature counter-electromotive force, a voltage which is variable in magnitude in accordance with the car speed and in polarity in accordance with the direction of car travel than by the means herein described. As a consequence, it is not intended that this invention isto be limited to the specific means illustrated except in those claims subjoined hereto which set forth such specific means.

It is also to be understood that this invention is not limited to the particular form of equipment or circuits illustrated. Such equipment and circuits are to be considered as merely schematic and illustrative of two manners of reducing the invention to a concrete operative system.

What is claimed is:

1. In an elevator installation; a body movable in the hatchway; means for raising and lowering said body; a rotatable member; a flexible transmission member secured at one end to said body and extending around said rotatable member; electric motive means connected to said rotatable member; and electric means, including means actuated in accordance with the speed and direction of motion of said rotatable member, Ior causing said motive means to apply a 4 and possessed of no upkeep difficulties. The tape substantially constant torque to said rotatable member as it is rotated in one direction, regardless of the speed of rotation thereof.

2. In an elevator installation; an elevator car; connections to said car by which it is raised and lowered; a device having a member for actuation in accordance with the movement of the elevator car; means connecting said member with the elevator car independently of the connections to said car for raising and lowering it, said means including a flexible transmission member and a reel for taking up the flexible transmission memher when the'car moves in the direction which would create slack in said flexible transmission member but for the taking up of said flexible transmission member by said reel; a dynamoelectric machine connected to said reel; and means, including electric means responsive to car movement, for causing said dynamo-electric machine to apply to said flexible transmission member, through the intermediary of said reel, a tensioning force of a magnitude that is substantially the same when the car is in motion in the said direction as when the car is stationary, whereby said member of said device is actuated, through the intermediary of said flexible transmission member and said reel, accurately in accordance with the movement of the elevator car.

3. In an elevator installation; an elevator car; connections to said elevator car by which it is raised and lowered; a flexible transmission member extending from said elevator car to at least one of the limits of movement of said car; means at one end of said flexible transmission member for securing it to the car, and at the other end to the hatchway, said means for one end includ ing a reel to which said one end is fastened and upon which said flexible transmission member is adapted to be wound; a dynamo-electric machine connected to said reel; and electric means dependent upon the speed and direction of motion of said car for causing said dynamo-electric machine to deliver torque to said reel in the direction tending to wind said flexible transmission member up on said reel that is substantially the same in magnitude Whether said car is stationary, moving upwardly, or moving downwardly.

4. In an elevator installation having an elevator car and connections thereto by which it is raised and lowered; a device having a member 'for actuation in accordance with the movement of the elevator car; and means for accurately actuating said member in accordance with the movement of said elevator car, comprising, a rotatable reel operatively connected to said member, a single tape connected at one end to said elevator car and at the other to said reel an electric motor operatively connected to said reel, and electric means including means actuated in accordance with the speed and direction of mo-,

tion of said elevator car, effective, when said elevator car is stationary, for causing said electric motor to exert a certain torque upon said reel, and thus maintain said tape under extension, and effective when the elevator car is in motion in either direction at any operating 'speed, for causing said electric motor to exert a torque upon said reel that is substantially the same, both in magnitude and in direction, as said certain torque.

5. In an elevator installation having an ele- ,vator car and connections thereto by which it is raised and lowered; a device having a member for actuation in accordance with the movement of the elevator car; and means for accuher, a single tape connectedat one end to said elevator car and at the other to said reel, a dynamo-electric machine operatively connected to said reel, and adapted, when energized, to rotate said reel in a direction to wind up said tape thereon, and to keep said tape under tension, while said car moves in one direction, and means for varying the electric power applied to said dynamo-electric machine in proportion to the work required to keep saidtape under tension as the speed of said car in said one direction varies from zero speedto full speed.

6. In an elevator installation having an elex vator car and connections thereto by which it is raised and lowered; a device having a memher for actuation in accordance with the movement of the elevator car; and means for accurately actuating said member in accordance with the movement of said elevator car, comprising, a rotatable reel operatively connected to said member, a single tape connected at one end to said elevator car and at the other to said reel, whereby movement of said elevator car in one direction unwinds said tape from said reel, a dynamo-electric machine operatively connected to said reel, and adapted, when energized, to keep 'said tape under tension while said car is stationary and while said reel is being rotated by said car when moving. in the direction to unwind said tape from said reel, and to rotate said'reel in the opposite direction to wind up said tape thereon, and to keep said tape under tension, while said car moves in the other direction, and means for varying the electric power delivered by and applied to said dynamo-electric machine in proportion to the work requiredto keep said tape under tension.

- '7. In an elevator installation including an elevator car and connections to it by which it is raised and lowered; a tape extending from said elevator car to a member above said elevator car;

means at each end of said tape for securing it, on the one hand, to the car, and on the other hand, to said member, one of said means including a reel upon which said tape is adaptedto be wound;

' a source of constant voltage; a source of variable voltage; and a dynamo-electric machine operatively connected to said reel and controlled by the conjoint action of said source of constant voltage and saidsource oflvariable voltage for maintaining saidtape under tension while said reel is in motion, in either direction, as well as while saidthe one hand, to the car, and on the other hand, I to said member, one of said means including a reel upon which said tape is adapted to be wound; an electric motor with 'its armature operatively connected to said reel; means for energizing said motor so that it tends to cause rotation of said reel in the direction to wind up said tape thereon;

and means, efiective when said reel rotates to' wind up said tape thereon or to unwind it therefrom, to insert in the armature circuit of said" motor a voltage which v'ariesin magnitudein accordance with the speed of rotation of said reel and in polarity in accordance with the direction of rotation of said reel, so as to compensate for the induced voltage generated in the armature of said motor when said reel rotates;

9. In an elevator installation including an elevator carand connections thereto by which it is raised and lowered; a member for actuation in accordance with the movement of said elevator car; a reel operatively connected to said member; a tape, extending in said hatchway, secured at one end to said elevator car and adapted to be taken in and payed out by said reel upon vertical movement of said car in one or the other direction thereof, respectively; an electric motor operatively connected to said reel; a source of voltage of constant magnitude and polarity; a source of voltage of a magnitude proportional to the speed of movement of said car and of a polarity dependent upon the direction of movement of said car; and means for supplying current to the armature of said motor from said two sources of voltage conjointly so as to maintain said current substantially constant in magnitude and direction of flow. a

10. In an elevator installation having an elevator car and connections thereto for raising and lowering it; a selector machine for said installation; a reversible reel operatively connected to a movable element of said selector machine; a single flexible transmission member connected at one end to said elevator car and at the other end to said reel, said reel being rotated by movement 105 of said car in the down direction to unwind said flexible transmission member from said reel; a source of constant voltage; a source of variable voltage; and an electric motor operatively con- ,nected to said reel and controlled by' the conjoint Y flexible transmission member under tension while said car is stationary and while said reel is being rotated by said car, when-moving in the down direction, to unwind said flexible transmission member from said reel, and for rotating said reel in the opposite direction" to wind said flexible transmission member thereon, when said car moves in the up direction, whereby said reel is driven so as to cause said movable element of said selector machine to operate in accordance with the movement of said elevator car.

11. In an elevator installation having an elevator car and connections thereto for raising and lowering it; a selector machine for said installation; a reversible reel operatively connected to a movable element of said selector machine; a single tapeconnected at one end to said elevator car and at the other end to said reel, whereby movement of said elevatorcar in the down direction unwinds said tape from said reel; a dynamoelectric machine operatively connected to saidreel, and adapted, when energized. to apply torque to said reel for keeping said tape under tension while said car is stationary and while said reel is being rotated by said car when moving in the down direction, and for rotating said reel in the opposite direction to wind up said tape thereon and to keep said tape under tension, while said car moves in-the up direction: and means for causing such torque applied by said dynamo-electric machine to said reel to be substantially constant in magnitude and direction regardless of the speed and direction of motion of said car, said means comprising means for controlling the amount of power delivered to and supplied by said dynamo-electric machine in accord- -ance with the work expended in applying such constant torque to said reel as said car moves up and down.

12. In an elevator installation having an ele-- vator car and connections thereto for raising and lowering it; a selector machine for said installation; a reversible reel operatively connected to a movable element of said selector machine; a single flexible transmission member connected at one end to said elevator car and at the other end to said reel, said reel being rotated by movement of said car in the down direction to unwind said flexible transmission member from said reel; an electric motor operatively connected to said reel and adapted, when energized, to keep said flexible transmission member under tension while said car is stationary and while said reel is being rotated by said car, when moving in the down direction, to unwind said flexible transmission member from said reel, and to rotate said reel in the opposite direction to wind said flexible transmission member thereon when said car moves in the up direction, whereby said reel is driven so as to cause said movable element of said selector machine to operate in accordance with the movementof said elevator car; and means for counteracting the counterelectromotive force induced in the armature of said motor while said armature is rotated, said means comprising a source of voltage the magnitude of which is substantially proportional to the speed of movement of the elevator car and the polarity of which is dependent upon the direction of movement of the elevator car.

13. In an elevator installation having an elevator car and connections thereto for raising and lowering it; a selector machine for said installation; a reversible reel operatively connected to a movable element of said selector machine; a single tape connected at one end to said elevator car and at the other end to said reel, whereby movement of said elevator car in the down direction unwinds said tape from said reel; a direct current electric motor operatively connected to said reel, and adapted, when energized, to apply torque to said reel for keeping said tape under tension while said car is' stationary and while said reel is being rotated by'said car when moving in the down direction, and for rotating said reel in the opposite direction to wind up said tape thereon and to keep said tape under tension while said car moves in the up direction; and means for causing said direct current motor to have a substantially constant torque whether at standstill or in motion in either direction, said means comprising a source of voltage the magnitude of which varies in accordance with the speed of the elevator car and the polarity of which is dependent upon the direction of movement of the elevator car.

14. In an elevator installation having an elevator car and connections thereto for raising and lowering it; a device having a member for actuation in accordance with the movement of said elevator car; a reel operatively connected to said member; a tape, extending in the elevator hatchway, secured at one end to said car and adapted to be taken in and payed out by said reel upon vertical movement of said car in one or the other direction, thereof, respectively; a direct current motor operatively connected to said reel; a source of constant, direct current voltage; means for exciting the field of said motor from said source; and a circuit, including the armature of said motor, connected to said source, said circuit including in addition a current limiting resistance and a sourceof variable direct current voltage, the magnitude of which depends upon the speed of said car and the polarity of whichdepends upon the direction of movement of said car.

15. In an elevator installation, a drive for a member movable in accordance with car movement, comprising; a rotatable member; connections from said rotatable member to said car; a separately excited direct current motor operatively connected to said rotatable member; a direct current source of constant voltage; means for connecting the field of said motor to said source; .a circuit for the armature of said motor, said circuit having an ohmic resistance of a definite amount and having interposed therein a source of variable voltage; and means for connecting said circuit to said source of constant voltage.

16. In an elevator installation including an elevator car and connections to it by which it is raised and lowered; a tape extending from said elevator car to a member above said elevator car; means at each end of said tape for securing it, on the one hand, to the car, and on the other hand, to said member, one of said means including a reel upon which said tape is adapted to be wound; a direct current electric motor operatively connected to said reel; a source of constant direct current voltage; means connecting the field of said electric motor to said source of constant voltage, whereby the net effective field flux of said electric motor is substantially constant in magnitude and direction; means connecting the armature of said electric motor to said source of constant voltage; current limiting resistance in the armature circuit of said electric motor for limiting the magnitude of current flowing therein when the elevator car is stationary and thus, when said reel and the armature of said electric motor are stationary, so that, when said elevator car is stationary and said electric motor is energized, said electric motor exerts a certain fixed value of torque upon said reel tending to wind up said tape; and a source of variable direct current voltage in the armature circuit of said electric motor for compensating for the induced voltage generated in the armature thereof when rotating in the flux produced by the field thereof, said source of variable voltage varying in magnitude in accordance with the speed of movement of said car and being substantially equal to the magnitude of the induced voltage generated by the motor armature due to the movement of said car, and varying in polarity in accordance with the direction of movement of said car and being opposite to the polarity of said induced voltage generated in the motor armature, so that said motor exerts a torque upon said reel; during winding up of said tape when the car travels in one direction and during unwinding of said tape when the car travels in the other direction, which, for all speeds of movement of said car, substantially the same, in magnitude and direction, as said certain torque that is exerted when said car is stationary.

17. In an elevator installation having an elevator car and connections thereto for raising and lowering it; a selector machine having a vertically movable member; and means actuating said vertically movable member in accordance with the movement of the elevator car, but oppositely to the direction of movement of said car, said means including a single flexible transmission member secured at one end to said car, a rotatable member around which said flexible transmission member passes, and power means operativelyconnected to said rotatable member to maintain said flexible transmission member under tension.

18. In an elevator installation having an elevvator car and connections thereto for raising and lowering it; a rotatable member; a flexible transmission member extending from said car to at least the upper, limit of movement of said car, and thereafter passing around said rotatable member so that force may be transmitted from the rotatable member to said flexible transmission member; means for securing the lower end of said flexible transmission member to said car; a dynamo-electric machine operatively connected to said rotatable member; means, effective when said car is in motion in the up direction, for en ergizing said dynamo-electric machine so that it rotates said rotatable member in the direction to take in said flexible transmission member; a selector machine having a vertically movable member; and mechanical means connecting said rotatable member with said vertically movable member, said vertical movable member moving in the down direction when said car is in motion in the up direction, whereby the weight of said vertically movable member tends to assist said dynamo-electric machine to rotate said rotatable member. 19. In an elevator installation; a movable body; means including connections thereto for moving said body vertically in the hatchway; switching mechanism for actuation in accordance with the movement of said movable body, said mechanism including a member having appreciable weight movable in a vertical path asgsaid switching mechanism is actuated, said path having as the maximum vertical travel for said member a travel that is only a fraction of the maxi mum vertical travel of said movable body; a flexible transmission member connected at one end to said movable body and extending to at least the upper limit of movement of said body; and means, including motion reducing mechanism, for mechanically connecting said flexible transmission member to said switching mechanism so I a small fraction of the maximum vertical movement of said body; and means for operatively connecting said body to said crosshead so that said crosshead moves.upwardly upon downward.

movement of said body and so that said crosshead moves downwardly upon upward movement of said body, with the movement of said cross-' head in both directions being in accordance with the amount of movement of said body in the respective directions of movement of said body,

and a drive for said crosshead for moving it oppositely to the direction of movement 01- said body in accordance with the amount of motion thereof, comprising, a single tape secured at one end to said body and extending upwardly past the upper limit or travel of said body, a rotatable reel to which the other end of said tape is secured for taking in and paying out said tape as said body moves up and down, a dynamo-electric machine operatively connected to said reel and adapted, when energized, for maintaining said tape under tension and for controlling the taking in of said tape by said reel when said body moves up and the paying out of said tape by said reel when said body moves down, means for varying the electric power delivered by and applied to said dynamo-electricmachine in proportion to the work required to keep said tape under tension as the speed of movement of said body in either direction varies from zero to full speed, and mechanical connections, including motion reducing mechanism, between said reel and said crosshead by which said crosshead is raised during downward movement of said body and is lowered during upward movement of said body.

22. In an elevator installation; a body movable in the hatchway; means for raising and lowering said body, .said means including an elevator hoisting motor; a Ward-Leonard control for said elevator hoisting motor, said control including 'a source of constant voltage; a rotatable member; a flexible transmission member secured at one end to said body and extending around said rotatable member; electric motive means connected to said rotatable member; and means for supplying to said motive means current derived from the algebraic sum of the voltage of said source and the voltage across the terminals of the elevator hoisting motor for causing said motive means to exert a substantially constant torque upon said rotatable member, regardless of the speed or direction of rotation thereof.

23. In an elevator installation including an elevator car and connections to it by which it is raised and lowered; a hoisting motor for said elevator car; a Ward-Leonard control for said hoisting motor, said control including a constant potential source of direct current; a tape extending from said elevator car to a member above said elevator car; means at each end of said tape for securing it, on the one hand, to the car, and'on the other hand, to said member, one of said means including a reel upon which said tape is adapted to be wound; a dynamo-electric machine operatively connected to said reel; and means for causing said dynamo-electric machine to be controlled conjointly by said constant potential source and by the voltage impressed by the Ward-Leonard generator on the armature oi. said hoisting motor for maintaining said tape under tension while said reel is in motion, in either direction, as well as while said reel is stationary. 4 24. In an elevator installation including an ele-- vator car, cables by which'said car is raised and lowered, and a sheave around which said cables extend; a tape extending from said elevator car to,a member above said elevator car; means at each end of said tape for securing it, on the one hand, to the car, and on the other hand, to said member, one of said means including a reel upon which said tape is adapted to be' wound; an electric motor with its armature operatively connected to said reel; means for energizing said motor so that it tends to cause rotation oi' said reel in the direction to wind up said tape thereon; and means, efiective when said reel rotates to wind up said tape thereon or to unwind it therefrom, to insert in the armature circuit of said motor a voltage which varies in magnitude in accordance with the speed of rotation of said reel and in polarity in accordance with the direction of rotation of said reel, so as to compensate for the induced voltage generated in the armature of said motor when said reel rotates, said means comprising a tachometer generator actuated from said sheave.

25. In an elevator installation having an elevator car and connections thereto by which it is raised and lowered; a device having a member for actuation in accordance with the movement of the elevator car; and means for accurately actuating said member in accordance with the movement of the elevator car, comprising, a rotatable reel operatively connected to said member, a single tape connected at one end to said elevator car and 'at the other to said reel, a source of constant direct current voltage, an electric motor operatively connected to said reel, said electric motor having a separately excited field energized by said constant voltage source and also having a series field in circuit with the armature of said motor, means for energizing the armature and series field of said motor from said constant voltage source so that, when said elevator car is stationary, said motor exerts a certain torque upon said reel to maintain said tape under tension, said series field being connected in said armature circuit so that the field resulting from the flow of current therethrough opposes the field created by said separately excited field, and means, effective when said elevator car is in motion in either direction, for inserting in said armature circuit a voltage the polarity of which is dependent upon the direction of movement of the elevator car and the magnitude of which is related to the speed of movement of the elevator car.

26. In an elevator installation; a body movable in the hatchway; connections to said body; a hoisting motor operating through said connections for raising and lowering said body; a control system for said hoisting motor to control the movements of said body; a device having a movable element for actuation in accordance with the movement of said. body; a drive for said movable element, said drive-including a single flexible transmission member connected to said body and an electric motor, operatively connected to said single flexible transmission member, adapted, when energized, for maintaining it taut regardless of the movements of said body; a brake for said electric motor; switching mechanism, when operated, for rendering said control system operable to control the movements of said body, said mechanism, upon restoration to its initial condition, rendering said control system inefiective to cause movement of said body and, in the event said body is in motion upon the restoration of said mechanism to its initial position, causing said control system to stop said body, said mechanism, when operated, also causing the energization of said electric motor and the release of said brake, and, upon its restoration to its initial position, causing the application of said brake and the deenergization of said electric motor; and means, responsive to any movement of said body and efiective in the event said mechanism is restored to its original condition while said body is in motion, for maintaining said brake released and said electric motor energized until after said body becomes substantially stationary.

27. In an elevator installation; a body movable in the hatchway; connections to said body; a hoisting motor operating through said connections for raising and lowering said body; a Ward- Leo'nard control for said hoisting motor, said control including a motor-generatr set and an exciter mechanically connected thereto and simultaneously operated therewith, and said control causing the stopping of said hoisting motor in the event said set is shut down while said hoisting motor is causing movement of said body; a device having a movable element for actuation in accordance with the movement of said body; a drive for said movable element, said drive including a single flexible transmission member connected to said body and an electric motor, operatively connected to said single flexible transmission member, adapted, when energized, for maintaining it taut regardless of the movements of said body; a brake for preventing the weight of said flexible transmission member overhauling said electric motor when deenergized; means for energizing said electric motor from said exciter;

means operable upon the shutting down of said set when said body is stationary for causing the application of said brake; and means, effective in the event said body is in motion when said set is shut down, for delaying the application of said brake by the operation of said preceding means until after said body becomes stationary.

28. In an elevator installation; a body movable in the hatchway; connections to said body; a hoisting motor operating through said connections for raising and lowering said body; a Ward- Leonard control for said hoisting motor, said control including a motor-generator set and an exciter mechanically connected thereto and simultaneously operated therewith, and said control causing the stopping of said hoisting motor in the event said set is shut down while said hoisting motor is causing movement of said body; a device having a movable element for actuation in accordance'with the movement of said body;

a drive for said movable element, said drive including a single tape connected to said body and an electric motor operatively connected to said single tape, through the intermediary of a reel,

adapted, when energized, for rotating said reel to maintain said tape taut regardless of the movements of said body; a brake which, when applied, prevents unwinding of said tape from said reel; means for energizingsaid electric motor from said exciter; a slack tape switch for the tape at the end thereof removed from said reel, said switch being operated when abnormal slack exists in said tape at such end; means, responsive to such operation of said slack tape switch, for deenergizing said electric motor, for

causing the application of said brake, and for stopping and preventing movement of said body; and means, operable upon the shutting down of said set, for causing the application of said brake only after said body is stationary and while said DAVID LEONARD LINDQUIST. JACOB DANIEL LEWIS.

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