US2989148A

US2989148A - Elevator control

Info

Publication number: US2989148A
Application number: US851043A
Authority: US
Inventors: Moser Richard
Original assignee: SCHWEIZ WAGONS AUFZUEGEFAB
Current assignee: SCHWEIZ WAGONS AUFZUEGEFAB; Schweizerische Wagons- und Aufzugfabrik A-G Schlieren-Zurich
Priority date: 1959-11-05
Filing date: 1959-11-05
Publication date: 1961-06-20
Anticipated expiration: 1978-06-20

Description

June 20, 1961 R. MOSER 2,989,148

ELEVATOR CONTROL Filed Nov. 5, 1959 3 Sheets-Sheet 1 1F 51 2 Ax Hg June 20, 1961 R. MosER ELEVATOR CONTROL Filed Nov. 5, 1959 Fig. 6

RV 2 K381 K2RU2 RU 2 3 Sheets-Sheet 5 K2 RS 2 K2 RS3 K4 RV1 i if&

This invention relates to elevator controls, and more particularly, to an elevator control circuit for an elevator control system to prevent undesired operation of an elevator cab.

It is important to provide in an elevator control system, controls and indicating devices which are efiective to provide at all times a positive control and indication of operation of an elevator cab. Use is made of mechanically free, but magnetically related elements in order to determine whether a shaftway door on one of the floors or stops for the elevator cab is open, whether the shaftway door is locked and whether the elevator cab cable is in a released position so that the elevator cab may be raised or lowered thereby.

This application is a combination-impart of my US. patent application Serial No. 723,560 filed March 24, 1958 for Elevator Control, now abandoned. Reference is made to copending U.S. patent application Serial No. 703,173 filed December 16, 1957 for Safety Device for Elevator Door and U.S. patent application Serial No. 848,719 filed October 26, 1959 which is a continuationin-part of application 703,173 in the name of Richard Moser et al. which application describe saturable magnetic devices and other mechanically free but magnetically related devices which may be used to energize the elevator control circuit of the present invention.

It is an object of the present invention to provide a positive, quick acting safety circuit which is responsive to electrical impulses for indicating the position of mechanical elements.

In order to accomplish the foregoing object, the present invention proposes the provision of related switching devices, such as transistor elements in which the collector-emitter circuit is maintained in a non-conductive condition and rendered conductive when an impulse is applied to the base of the transistor whereby to render the collector-emitter circuit conductive for energizing a relay so that switch contacts for the safety circuits are energized.

It is further proposed to provide a group of interrelated transistor circuits in which the base of one transistor circuit is rendered selective when the collector-emitter cincuit of another transistor is rendered conductive. Proper sequence of operation is obtained in accordance with the energization of the transmitting elements which comprise saturable magnetic devices having a high degree of rapid response to a change in position of the shaftway door, lock for the shaftway door and emergency circuit for the elevator cab. While the invention is described herein in the context of elevator control circuits for elevator control systems, it will be appreciated that it also has application to other problems of circuit controls.

For a better understanding of the invention, as Well as other objects and further features thereof, reference is had to the following detailed description to be read in "conjunction with the accompanying drawings, wherein like components in the several views are identified by like reference numerals.

In the drawings:

FIG. 1 is an elevational view partially in section illustrating a shaftway door with a door locking mechanism and a closing control device;

tet

FIG. 2 is an enlarged sectional view of a transmitting element comprising a pair of saturable magnetic devices for controlling the closing control device for the shaftway door;

FIG. 3 is a transverse section of the shaftway door showing the door locking control mechanism together with transmitting device comprising a saturable magnetic device therefor;

FIG. 4 shows a transmitting device comprising a saturable magnetic device for safety contacts to control the movement of the elevator cab cable; and

FIGS. 5 and 6 show two parts of a schematic wiring diagram for an elevator control system.

Referring now to FIG. 1 which shows an elevator shaftway door 50 and its associated door frame or iamb 51. Positioned at the top of door 50 and housed in the door frame 51 is a transmitting element 11 for controlling the closing position of the door. Mounted in the door frame 51 is a locking mechanism 60 comprising a roller lever 61 and a locking bolt 63 actuated thereby. An outside call button DA for calling an elevator cab, not shown, is also provided on the door frame 51. While only a single shaftway door 50 together with its associated elements has been shown, it will be understood that each floor of a structure provided with an elevator shaftway and cab may be provided with the same or similar door 50 together with its components.

Referring now to FIG. 2, the transmitting element 11 comprises two coils or

windings

52 and 53 interconnected on one side by means of an iron plate 56 and on the other side fixed to the door frame 51. Affixed to the side of the door Sil facing the shaftway is a core 54 pro 'vided with two core legs 54' and 54" which fit within

coils

52 and 53, respectively, the door frame being provided with an opening 55 slightly larger than core 54 so that it can fit within opening 55 and with its legs 54' and 54" in

coils

52 and 53 when the door is in its closed position. Coil 52 is excited by an alternating current as will be explained subsequently in connection with the circuit of FIGS. 5 and 6 which produces a flux in the core 54 when the door 50 is closed and the iron plate 56, and, by transformer action coil 52 induces an alternating current voltage in coil 53. When the door 50 is in its open position, the iron plate 56 immediately becomes saturated when some A.C. current flows through coil 52 so that there is presented a high impedance to the flow of A.C. current through the coil 52. When iron plate 56 causes coil 52 to present a high impedance to the flow of current therethrough, practically none or a negligible A.C. voltage is induced into coil 53 by iron plate 56 and coil 52 since a very small or no A.C. current flows through coil 52 so that there is no flux linkages between

coils

52 and 53. When the door 50 is closed

core legs

54 and 54 are positioned within

coils

52 and 53 and coil 52 presents a low impedance to the flow of A.C. current therethrough, since core 54 is made of a saturable magnetic material.

Referring now to FIG. 3 of the drawings which shows the locking mechanism 60 to maintain door 50 in a locked condition to an enlarged scale and comprises a housing 62 of magnetically non-conductive material together with the locking bolt 63 guided therein. The locking bolt cooperates with a locking lever 64 which is actuated by the roller lever (see FIG. 1). When the door is closed, the locking bolt 63 engages the shaftway door 50 and prevents an unintentional opening of same. Housing 62 is provided with a pair of aligned apertures which are aligned with an aperture in the door frame 51 and shaftway door 5'0 in the closed position thereof. The pair of apertures in the housing 62 guide the movement, shown as being in a horizontal direction, of the locking 3 bolt 63, and the apertures in the door and door frame are aligned to provide the locking action.

Housing 62 also contains a transmitting device comprising a core 65 of saturable magnetic mateiial having a Winding 67 thereon and juxtaposed to core 65 is a core 66 made of saturable magnetic material and having a winding 68 thereon.

Cores

65 and 66 are positioned relative to each other so as to provide an air gap therebetween into which moves a magnetically short circuiting lug or plate 69 having a leg which is fixedly coupled to locking bolt 63 for movement therewith. When locking bolt 63 is moved so as to become engaged with the aligned apertures in the door frame and door, the lug 69 is moved outside of the air gap between

cores

65 and 66. The coil 67 is energized with alternating current producing in the core 65 a change of flux which is transmitted, when the door is locked, by way of the air gap to the core 66 and induces therein an alternating current potential in the winding 68. If the door is unlocked, the short-circuit lug 69 enters the air gap and interrupts the flux between the

cores

65 and 66 so that no flux is induced in winding 68 causing it to be free from voltage. Consequently, no A.C. current is induced in winding 68 by winding 67.

FIG. 4 shows a contactless or mechanically free, but magnetically related transmitting element 1 of the type used for safety contacts in safety circuits, for example, slack rope switch contacts, safety brake contacts, etc. Transmitting element 1 comprises a housing 75 which is convered by a cover 76 having an opening through which passes a core bolt 80. Fixed on the bottom of the housing is a double coil structure 77 comprising two windings or

coils

78 and 79. The core bolt 80 which is guided in the housing 75 and cover 76 is composed of two members, a core 81 extending into the hollow space of the double coil structure 77 and a guide pin 82 provided with a shoulder made of a non-magnetizable material which is pressed into the core 81 by means of a pin 87. The core 81 is maintained in the position shown in the drawing by means of a spring 83 bearing on coil structure 77 and the shoulder of the guide pin 82. The winding 78 is energized with an alternating current and a flux induced into the core 81 induces an alternating potential in the winding 79. If a force acts on the core bolt 80 forcing it against the force exerted by the spring 83, the core 81 moves out of reach of the winding 78 so that it is no longer possible to induce an alternating current into the core 79. Core bolt 80 may be used as an emergency button to provide for an automatic gripping of the elevator cables 95 and prevent operation or movement of cab 94. It will be understood that when the shoulder of guide pin 82 becomes engaged with the double coil structure 77, the shank portion 82 of the guide pin 82. is moved into the position formerly held by core 81 and since it is of non-magnetic material, the flux linkages between

windings

78 and 79 are negligible so that they may be ignored. An elevator cab 94 (diagrammatically shown in FIG. 5) is supported by the usual elevator cables 95 (only one being shown). At their ends these cables 95 are provided with a conical head 99 coacting with a conical seat in a top plate of an upper frame 100 connected to the cab 94-. A safety lever 103 is pivotally mounted between transmitting element 1 arranged on the top of the cab 94 and the top plate of the frame 100 and held in horizontal position by means of a spring 104. Upon a break of cable 95 the conical head 99 falls out of its seat onto the safety lever 103 which in turn rocks downwardly and pushes the core bolt 89 into the housing 75 thereby to displace core 81 from its position as shown in FIG. 4 and move the guide pin 82 into this position so as to prevent the energization of winding 79 by winding 78.

Referring now to FIG. 5 of the drawings which illustrates a novel circuit for an elevator control system, a three phase power source having conductors R, S and T is provided for energizing an elevator motor 90. Motor is of the reversible type, and switches RUl' and RUZ are coupled to conductors S and T and motor 90 for providing upward motion and downward motion, respectively, to the elevator cab 94. As is well known, in elevator devices, the driving motor 90 drives a gear drive 92 by way of a brake 91 composed of brake disc, brake shoe and braking magnet solenoid MB. A driving pulley 93 is fixed on the slowly running shaft of the gear drive 92, the elevator cab 94 being suspended from one end and a counterweight 96 being suspended from the other end of the cable which is guided over the pulley 93. Call buttons DC are arranged in the cab 94-. Fixed on the cab is a movable slideway 97 which actuates shaft switches JS1-3 fixed in the shaftway, one of which switches I8 is associated with each stop or floor. A locking magnet MV which cooperates with a movable slideway 98 is also mounted on the cab; the slideway 98 actuates the roller lever 61 (FIG. 1) and the door lock 60 (FIG. 3) connected to the latter. The novel circuit will be explained in connection with an elevator control system which is adapted for three floors or stops, it being understood that any number of n stops or floor-s may be provided.

Also coupled to conductors S and T is a primary winding of an iron core transformer Tr1 having two secondary windings and 111. The general symbols used in the wiring diagram are set forth as follows:

DA13Outside or door call buttons DC13Cabin call buttons JS13fiShaft switches KJSl-3Switch contacts of the shaft switches KRSAwitch contacts of the floor relays KRUAwitch contacts of the relays KRVSwitch contacts of the pilot or pre-control relays RSl-3Floor relays RUlRelay for upward motion RUZ-Relay for downward motion RV--Pilot or pre-control relay One secondary winding 110 of the transformer Trl is coupled to a rectifier GL1, the positive output of which is connected to a common positive conductor 1000 and the negative output of which is connected to a common negative conductor 101 of the elevator control.

The secondary winding 111 of the transformer Tr1 is connected to the

conductors

112 and 113 connected to a three-part safety circuit which forms the subject matter of this invention.

The first part of the safety circuit comprises the transmitting element 1 for the safety contacts and includes a winding 78 coupled to

conductors

112 and 113. FIG. 4 illustrates the typical contactless or mechanically free, but magnetically related-transmitting element 1 of which winding 78 forms a part together with its associated winding 79. Another transmitting element 2 comprising

windings

78 and 79 identical with the element 1 of FIG. 4 is also shown schematically with the windings 79 of

elements

1 and 2 connected together in series. The transmitting

elements

1 and 2 are mounted on the cab 94 for the control of the gripping or safety and slack cable device.

One free end of the winding 79 of the transmitting element 1 is connected to the base of an amplifying element such as a transistor 6. The collector of the transistor 6 leads by way of a circuit element, for example, a relay RT1, to the conductor 101. A smoothing condenser 10 is connected in parallel with and by-passes the relay RT1 to smooth the current energizing relay RT1 and to prevent arcing and a false holding at the contacts thereof. The emitter of the transistor 6 is connected to a neutral or grounded conductor 102 by means of a conductor 114. A limiting (peak-limiter) diode 7 is arranged between the emitter and the base of the transistor. A compensation or voltage balancing network 5 composed of resistors 115- and 116 connected in series is arranged between the

conductors

114 and 1000. The other free end of the winding 79 of the transmitting element 2 is connected to the voltage balancing network 5 to the common connection of resistors 115 and 116, the other ends of which are coupled to

conductors

102 and 1000, respectively.

The second part of the safety circuit comprises contactless or mechanically free, but magnetically related transmitting

elements

11, 12 and 13 for the safety control device of the shaft way doors 50; while only transmitting element 11 is shown in FIG. 2, it is understood that

elements

12 and 13 are identical with element 11. The

conductors

112 and 113 are also connected to the second part of the safety circuit with the windings 52 of the

contactless transmitting elements

11, 12, 13 for the closing controls of the doors according to FIG. 2. One end of the winding 53 of the transmitting element 11 is connected to the base of an amplifying element such as a transistor 17, while the other end is connected by means of a conductor 124 to a voltage balancing network 14 comprising the

resistors

120, 121, 122 and 123 connected in series, the resistor 120 being connected to the conductor 101 and the resistor 123 being connected to the conductor 1000. Similarly, one end of the windings 53 of the transmitting

elements

12 and 13 are connected by way of

conductors

125 and 126 to the voltage balancing networks 15 and 16, respectively, the voltage balancing networks consisting of the resistors 120-123. The other ends of windings 52 of

elements

12 and 13 are coupled directly to the base of transistors 18 and 19, respectively. The emitter-collector circuit of transistors 17, 18 and 19' leads from the conductor 102 to the emitter of transistor 19 and by way of the sequentially connected collectors and emitters of the

transistors

19, 18 and 18, 17, the collector of transistor 17 and circuit element, for example, relay RT2 to the conductor 101. A smoothing condenser 23 of the same type as condenser 10 is connected in parallel to the relay RT2.

The third part of the safety circuit comprises the locking mechanism 60, previously described in connection with FIG. 3 of the drawings, comprising a winding 67 for each of identical contactless or mechanically free, but magnetically related transmitting elements 25 26 and 27. While only transmitting element 25 is shown in FIG. 3,

elements

26 and 27 are identical with element 25, it being understood that an element such as element 25 is provided for each shaftway door. Each winding 67 is coupled to

conductors

112 and 113 and is magnetically related to an associated or secondary winding 68. One end of the winding 68 of transmitting element 25 leads to the base of an amplifying element such as a transistor 29 while the other end is connected to a voltage balancing network 32 consisting of resistors 130 and 131, the resistor 130 being connected to the emitter of a transistor at a connection point 137 and the resistor 13 1 being connected to the conductor 1000. There are n balancing networks, one for each of the 11' stops and n transistors associated therewith. All of the balancing networks with the exception of the nth balancing network are coupled similarly. The emitter of transistor 30 is also coupled from the connection point 137 through a resistor 36 which is by-passed by a smoothing condenser 40 to conductor 102.

In a similar manner, winding 60 of transmitting element 2.6 has one end coupled to the base of a transistor 30 and the other end to a voltage balancing network 33 comprising

resistors

132 and 133. The resistor 132 of the voltage balancing network 33 leads to the emitter of the transistor 31, at a connection point 136 and the resistor 133 is coupled to conductor 1000. The emitter of transistor 31 is coupled from the connection point 136 through a resistor 37 which is bypassed by a smoothing condenser 41 conductor 102. Winding 68 of element 27 has one end coupled to the base of a transistor 31 and the other end coupled to a voltage balancing network 34 comprising resistors 134 and 135. Resistor 134 which is part of nth balancing network is coupled to'conductor 101 and resistor 135 is also coupled to conductor 1000. Also coupled to conductor 101 are the collectors of the

transistors

29, 30 and 3 1. The emitter of the transistor 29 is connected by way of a circuit element, for example, a relay RT3, to the conductor 102. A smoothing condenser 39 is connected in parallel to the relay RT3.

Also coupled between the negative and

positive conductors

101 and 1000 are a number of additional circuit elements for the elevator control system; with the elevator cab 94 stopped at the second floor, the circuit elements are shown in their normal position. In the line of conductor 101, switch contacts KRTI and KRTZ are shown in their normally closed position indicating that their associated relays RT1 and RT2, respectively, are energized. Coupled between

conductors

101 and 1000 are the circuits for energizing relays RS1, RS2, RS3, RV1, RV2, RU1 and RU2, magnet MV and braking solenoid MB when the switches in the circuits are closed. The relay RS1 is coupled from conductor 1000 through the parallel circuit of the outside call button DAl and cabin call button DC1 through braking solenoid switch KMB to conductor 101; switches -DA-1 and D01 are shown in their open position to maintain the relay RS1 deenergized. Similarly, the relays RS2 and RS3 are coupled through their associated call buttons DA2, IDA-3 and DC2, DC3, respectively, to braking solenoid switch KMB. Switch contacts K1RS1, K1RS2 and K1RS3 are coupled through holding switch K1RV1K1RV2 between

conductors

101 and 1000. When relays RS1, RS2 or RS3 are energized, switch contacts K1RS1, K1RS2 or K1RS3 and KZRSI, K2RS2 or K2RS3, respectively, are closed. The contact shaft switches K181 are normally closed when the cab is not at the stop or floor; since cab 94 is at the second stop switch contacts K181 and K183 are shown in their closed position with switch contact KJSZ shown in its open position. The relay RV1 is coupled from conductor 1000 and is coupled through contact switches K2RV2, KISS and K2RS3 or KJS2, K2RS2 to conductor 101; similarly, relay RV2 is coupled from conductor 1000 through contact switches K2RV1, K181 and K2RS1 or KJSZ, KRSZ to conductor 101. When relay RV1 is energized, switch contacts KIRVl, K3RV1 and K4-RV1 are closed, and when relay RV2 is energized, switch contacts KlRVZ, K3RV2 and K4RV2 are closed. Energization of contact switch K1RV1 or K1RV2 completes the holding circuit for relays RS1, RS2 or RS3 causing them to remain energized after the outside call buttons or cab call buttons are released.

Relay RT is deenergized when any one of the shaftway doors 50 is open and is energized when all shaftway doors 50 are locked. Switch contact KRT3 is closed when relay RT3 is energized. Relay -RU1 is coupled between

conductors

1000 and 101 through switch contacts KZRUZ, K4RV2 and KRT3, and relay RU2 is coupled between

conductors

1000 and 101 through switch contacts K2RV1 and KRT3. Relay RU1 is energized when relays RV2 and RT3 are energized to close switch contacts K4RV2 and I IRT3 and cause switch contact RUl to close. Similarly, switch contacts RUZ are closed when relay RUZ is energized after relays RV1 and RT?) are energized to closed switch contacts K4RV1 and KRT3. Switch DH is a master control switch which when opened prevents operation of the elevator cab 94 by maintaining brake 91 locked since the circuit between

conductors

101 and 1000 is open.

The braking solenoid MB is coupled between

conductors

1000 and 101 through the parallel connection of switches KlRUl and K1RU2. When switch control K1RU1 or K2RU2 is closed, the braking solenoid MB is effective to release the brake shoe of brake 91 from the disc thereof to permit the cab 94 to move. Locking magnet MV is coupled between

conductors

1000 and 101 through the parallel connection of switch contacts K3RV1 and K3RV2. When switch contacts K3RV1 or K3RV2 is closed, locking magnet MV is energized in order to main tain the door 50 for each stop or floor in its locked condition, and when locking magnet MV is deenergized, the door 50 at the stop may be opened. Switch contacts K2RV1, K2RV2, when opened serve to maintain the relays RUI and RUZ deenergized when servicing or performing a maintenance operation.

As shown in FIG. 6, the cab 94 is in a position of rest at the second stop, since the contact KJSZ of the shaft switch 182 is in middle position. The windings 78 of the transmitting elements 1, 2 (FIG. 5) for controlling the gripping or safety device and the slack cables are excited. The voltages induced in the windings 79 reach the base-emitter circuit of the transistor 6 by way of the voltage balancing network 5 and conductor 114.

The potential of the voltage balancing network 5 is so selected that, in the absence of any induced voltage in any of the transmitting

elements

1 or 2, the voltage at the base of the transistor 6 becomes positive with respect to the emitter and blocks the collector-emitter circuit. Where there are provided a larger number of sequentially connected windings 79, with corresponding selection of the voltage balancing network 5, the limiting diode 7 prevents a rise of a positive voltage which would be detrimental to the transistor 6. Only when all induced voltages are present in the windings '79, will a part of the negative half-Wave of the sequentially connected transmitting

elements

1 or 2 overcome the positive potential of the voltage balancing network 5 causing the base of the transistor 6 to become negative with respect to the emitter and the collector-emitter circuit to become conductive, so that a pulsating direct current flows from the conductor 102 through conductor 114, transistor 6 and relay RT1 to the conductor 101 and operates relay RT1. The condenser 10 serves to smoothen the pulsating direct current flowing through the relay RT1 in order to prevent the relay from buzzing or vibrating.

The windings of the transmitting

elements

11, 12, 13 for the safety control device of the doors are excited. The voltages induced in the windings 53 act by way of the voltage balancing networks 14 or 15 or 16 of the baseemitter circuit of the corresponding transistors 19, 18, 17. The values of the potentials of the voltage balancing networks 14, 15, 16 are so selected that, in case of possibly occurring rest potentials in the windings 52 with the doors open, the potentials at the bases of the transistors 17, 13, 19 can never become negative with respect to the emitters.

Only when the door is closed and and the induced potential is present in the winding 53 of the transmitting

element

11 or 12 or 13, will the negative-wave overcome the positive potential of the voltage balancing network 14 or 15 or 16, thereby causing the bases of the transistors 17 or 18 or 19 to become negative with respect to their emitters and cause the collector-emitter circuits to become conductive. When all collector-emitter circuits of the transistors 17, 18, 19 are conductive, a pulsating direct current is caused to flow from the conductor 102 by way of the transistors 19, 18, 17 and through the relay RT2 to the conductor 101 causing an attraction or energization of the relay RT2.

When the windings 67 of the transmitting

elements

25, 26, 27 (FIG. 6) for controlling the locking of the doors are also energized, then the potentials induced in the windings 68 act through their associated voltage balancing networks 32, 33, 34 on the base-emitter circuits of the transistors 29, 30 and 31. The value of the potentials of the voltage balancing networks 32, 33, 34 is so selected that, in case of possibly occurring rest potentials in the windings 68 with the doors are open, the potentials at the bases of the transistors 29, 30 and 31 are such that the bases can never become negative with respect to their emitters.

The potential induced in the coil 68 of the transmitting elements 27 causes the base of the transistor 31 to hecome negative with respect to its emitter and thereby causes its collector-emitter circuit to become conductive. A pulsating direct current now flows from the conductor 101 through the transistor 31 and resistor 37 to the conductor 102; this causes the potential on the point 136 to become negative with respect to its previous potential when transistor 30 was non-conductive, thereby the transistor 30 becomes selective for the potential induced in the winding 68 of the transmitting element 26. Thus, the base of the transistor 30 can only become negative with respect to its emitter when the induced potential in the winding 68 of the transmitting element 26 is fully present. Consequently, a pulsating direct current flows from the conductor 181 through the transistor 30 and the resistor 36 to the conductor 102; this causes the potential at the point 137 to become negative, whereby the transistor 29 becomes selective in the same manner as transistor 39. Now, if there is also an induced potential in the winding 68 of the transmitting element 25, then the transistor 29 also becomes conductive, and a pulsating direct current is able to flow from the conductor 101 by way of the transistor 29 and the relay RT3 to the conductor 102 causing the relay RT3 to become energized and operative.

A practical example of the control circuit will be illustrated by the following explanations and example. The transmitting

elements

1 and 2 are excited or energized since the gripping or safety and slack cable controls have not responded. Relay RT1 is energized so that contact switch K'RTI is closed. Since all doors are closed, the transmitting

elements

11, 12 and 13 are excited, so that relay RT2 is energized and contact switch KRTZ is closed. Since the cab 94 is at the second stop or floor, the corresponding door is not locked, so that the winding 68 of the transmitting element 26 is free from voltage, the relay RT3 is deenergized and the contact switch KRT3 is open and relay coils RUI and RUZ cannot be energized.

If one now operates, for example, the outside call button DAl, which is on the first floor, a direct current flows from the conductor 101 by way of the braking magnet contact KMB and the push button DAl and attracts the relay RS1. This causes switch contact K2RS1 to close and to energize the relay RV2 by way of switch contacts KJS1 and K2RV1. The holding circuit of the floor relay RS1 is closed by way of the switch contacts K1RV2 and K1RS1. The operation of the relay RV2 causes the contact K3RV2 to close and to energize the locking magnet MV. The movable slideway 98 is attracted and the locking bolt 63 locks the door of the transmitting element 26 causes the relay R3 to be energized and the switch contact KRTS to close, so that relay RU1 is energized through the circuit of the switch contacts K4RV2, K2RU2. By means of the contact KIRUI the braking magnet solenoid MB is energized and the brake shoe is removed from the brake disc of the brake 91. The motor now sets the elevator cab 94 in downward motion from the second stop to the first stop.

As soon as the cab 94 approaches the first stop, the shaft switch 181 is actuated by the slideway 97. The switch contact KJSI opens, relay RV2 and relay RUI are deenergized, the braking solenoid MB becomes deenergized and the brake 91 becomes operative to prevent motor 90 from operating cab 94. The locking magnet MV is deenergized, and the movable slideway 98 unlocks the door locking mechanism 68.

In the example described above, the three parts of the safety circuit have each their own operating member and switching arrangement. But, in most cases it will be advantageous to use the same switching arrangement for all three parts.

While there has been shown what is at present considered to be a preferred embodiment of the invention, it is apparent that many changes and modifications may be made therein without departing from the scope of the invention, and it is intended in the accompanying claims to cover all such changes and modifications as fall within the true spirit of the invention.

What is claimed is:

1. In an elevator control system having an elevator cab movable within a shaftway provided for each stop or floor, the elevator cab being coupled to a reversible driving motor through a braking device, a shaftway door provided for each floor -for entry into said cab and a safety circuit for preventing movement of said cab with an open cab door and open shaftway door comprising magnetically saturable transmitting elements: including a transistor having a collector-emitter circuit and a base circuit, a relay coupled in said collector-emitter circuit and operative in response thereto when rendered conductive, said transmitting elements being coupled to said base circuit to energize the same to render said collector-emitter circuit conductive, said relay being coupled to said safety circuit for interrupting the same when deenergized; said transmitting elements comprising a first winding coupled to a source of AC. potential, a second winding coupled to said base circuit and a movable core having a first and a second part, said first part being formed of saturable magnetic material and said second part being formed of non-magnetic material, said first winding being magnetically coupled to said second winding with said first part of said core positioned therein and being magnetically decoupled with said second part positioned therein; a voltage balancing network coupled to said collector-emitter circuit and through said second winding to said base circuit to provide a bias thereto to maintain said collectoremitter circuit non-conductive with said second winding magnetically decoupled from said first winding, said first part of said core when positioned within said windings magnetically coupling said first winding to said second winding to render said collector-emitter circuit conductive and energize said relay.

2. The elevator control system as claimed in claim 1, in which said core part forms part of an emergency control circuit, said second core part being positioned Within said first and second windings to decouple same to prevent operation of said elevator cab, and including a limiting diode coupled between said base and said emitter.

3. In an elevator control system having an elevator cab movable within a shaftway provided for each stop or floor, the elevator cab being coupled to a reversible driving motor through a braking device, a shaftway door provided for each floor for entry into said cab and a safety circuit for preventing movement of said cab with an open cab door and open shaftway door comprising magnetically saturable transmitting elements: including a transistor having a collector-emitter circuit and a base circuit, a relay coupled in said collector-emitter circuit and operative in response thereto when rendered conductive, said transmitting elements being coupled to said base circuit to energize the same to render said collector-emitter circuit conductive, said relay being coupled to safety circuit for interrupting the same when deenergized; said transmitting elements being provided for each stop and com prising a first and a second coil coupled to a door frame and a core element coupled to a door associated with said door frame, said core element when positioned within said first and second coils causing said coils to become magnetically responsive to each other whereby to energize said second coil when said first coil is energized; and including a transistor element for each said second coils, the base of each said transistor elements being coupled to one end of each said second coils respectively, the emitter-collector circuits of said transistor elements being serially connected to a source of potential and a voltage balancing network for each said second coils and transistor elements, the other end of each said second coils being coupled to its associated voltage balancing network, said voltage balancing network being effective to maintain the emitter-collector circuit of each said transistor elements non-conductive with the second coil associated therewith being deenergized;

4. The elevator control system as claimed in claim 3, including a relay coupled to said emitter-collector circuits and operable in response thereto when rendered conductive to operate said safety circuit whereby to permit the elevator cab to be moved within the shaftway.

5. The elevator control system as claimed in claim 4, in which each said voltage balancing network comprises. first, second, nth and n+1 serially connected resistors coupled to a source of reference potential, said other end of one of the secondary coils being coupled to the collector of said transistor associated therewith through said first resistor and said relay, said other end of a second one of said secondary coils being coupled to the collector of said transistor element associated therewith through said second and first resistors, said relay and said emittercollector circuit of said first-mentioned transistor element, and said other end of an nth one of said secondary coils being coupled to the collector of said nth transistor element associated therewith through said nth, second and first resistors, said relay and said emitter-collector circuits of said first and said second-mentioned transistor elements, so that potentials induced in said secondary coils act by way of the base-emitter circuits of said transmitting elements to render said emitter-collector circuits conductive to energize said relay when all said emittercollector circuits are rendered conductive.

6. The elevator control system as claimed in claim 5, in which said core element comprises a first and a second leg of saturable magnetic material to etfect'a positive coupling between said first and second coils to induce a potential therein when a potential is applied to said first coil and said first and second legs are inserted in said first and said second coils, respectively, said base circuit rendering said emitter-collector circuit associated therewith conductive when said core legs are inserted into said coils and said potential is applied to said first coils.

7. In an elevator control system having an elevator cab movable within a shaftway provided for each stop or floor, the elevator cab being coupled to a reversible driving motor through a braking device, a shaftway door provided for each floor for entry into said cab and a safety circuit for preventing movement of said cab with an open cab door and open shaftway door comprising magnetically saturable transmitting elements: including a transistor having a collector-emitter circuit and a base circuit, a relay coupled in said collector-emitter circuit and operative in response thereto when rendered conductive, said transmitting elements being coupled to said base circuit to energize the same to render said collector-emitter circuit conductive, said relay being coupled to safety circuit for interrupting the same when deenergized; a transistor element coupled to said transmitting element for each of 11 sto s, the collectors of each said transmitting elements being coupled together, a voltage balancing network for each said transistor element, each said transmitting element being coupled to a base of its associated transistor and its associated voltage balancing network to maintain said base positive with respect to the emitter of its associated transistor element when there is no potential applied to the base by the transmitting element and to render said base negative with respect to said emitter to cause the emitter-collector circuit to become conductive when a potential is applied to said base by said transmitting element.

8. The elevator control system as claimed in claim 7, in which a relay is coupled to said emitter of one of said transistor elements and a resistor device is provided for each and coupled to said emitter of said other transistor elements, said relay being energized when said emitter-collector circuits of each said transistor elements are rendered conductive and a current passes through each said resistor devices.

9. The elevator control system as claimed in claim 8, including a capacitor for each said resistor devices and said relay by-passing the same to smoothen the pulsating current flowing in the emitter-collector circuits.

10. The elevator control system as claimed in claim 8, in which said transmitting elements each include a first core element, a first winding on said first core element, a second core element juxtaposed to said first core element with an air gap provided therebetween, a second winding on said second core element and a magnetic short-circuiting element movable from a first position within said air gap and between said core elements and a second position removed from said air gap, said first winding when a potential is applied thereto induces a potential into said second winding when said magnetic short-circuiting element is in said second position and induces no potential into said second winding when said magnetic short-circuiting element is in said first position, said first position indicating that a shaftway door is unlocked and said second position indicating that said shaft- Way door is locked; said second winding having one end coupled to the base of its associated transistor element and another end coupled to its associated voltage balancing network and when said second winding is rendered conductive, the emitter-collector circuit of its associated transistor being rendered conductive.

11. The elevator control system as claimed in claim 8, in which said transmitting element comprises a first winding, a second winding and means magnetically coupling said windings to induce a potential into said second winding when a potential is induced into said first winding;

one end of said second winding being coupled to the base of its associated transistor and the other end of said second winding being coupled to its associated voltage balancing network.

12. The elevator control system as claimed in claim 11, in which each said voltage balancing networks comprises a first and a second resistor element coupled together at a common point to said other end of said second winding, said first and second resistor elements being serially connected through said common point, there being n serially connected "resistor elements, one end of each of said n-1 serially connected resistor elements being coupled to the emitter of a transistor associated with another one of said n serially connected resistor elements through one of said resistor devices to a source of reference potential, the one end of the nth serially connected resistor elements being coupled directly to a source of potential which is negative with respect to said source of reference potential and said other end of each of said serially connected resistor elements being coupled to a source of potential which is positive with respect to said source of reference potential, said emitter-collector circuits of said transistor element when conductive cause the emitter thereof to become more negative whereby said one end of said nl serially connected resistor elements become more negative to cause the base element of another one of the n transistors to become more negative and render its associated emitter-collector circuit conductive.

13. The elevator control system as claimed in claim 12, in which said relay is coupled directly to the emitter of the nth transistor so that the emitter-collector circuits of all n transistors must be rendered conductive by said transmitting elements.

14. The elevator control system as claimed in claim 13, including normally open switch contacts and normally deenergized relay controls coupled to and responsive to the energization of said relay, said relay when energized being efiective to energize said relay controls and close said normally open switch contacts to permit said elevator cab to move within the shaftway.

References Cited in the file of this patent UNITED STATES PATENTS 265,448 Sawyer Oct. 3, 1882 963,570 Humphrey July 5, 1910 1,344,430 Wigmore June 12, 1920 2,378,218 Hard June 12, 1945 FOREIGN PATENTS 1,093,539 France Nov. 24, 1954