US3261427A

US3261427A - Detector for ferromagnetic material in an elevator well and an elevator control system operated thereby

Info

Publication number: US3261427A
Application number: US297339A
Authority: US
Inventors: Morris Robert
Original assignee: STALEY ELEVATOR CO Inc
Current assignee: STALEY ELEVATOR CO Inc
Priority date: 1963-07-24
Filing date: 1963-07-24
Publication date: 1966-07-19
Anticipated expiration: 1983-07-19

Description

July 19, 1966 R. MORRIS 3,261,427

DETECTOR FOR FERROMAGNETIC MATERIAL IN AN ELEVATOR WELL AND AN ELEVATOR CONTROL SYSTEM OPERATED THEREBY Filed July 24, 1963 FIG. 3.

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ATTORNEYS.

United States Patent 3,261,427 DETECTOR FOR FERROMAGNETIC MATERIAL IN AN ELEVATOR WELL AND AN ELEVATOR CON- TROL SYSTEM OPERATED THEREBY Robert Morris, Bayside, Long Island, N.Y., assignor to Staley Elevator Company, Inc., Long Island, N.Y., a corporation of New York Filed July 24, 1963, Ser. No. 297,339 6 Claims. (Cl. 187-29) This invention relates to improvements in detector systems for detecting magnetic material, the system being responsive to the presence of such material in the field of the detector. The invention relates also to elevator controls having vanes along'the shaft for inductively controlling the operation of an elevator through the magnetic material detector system of this invention.

The expression magnetic material is used herein to designate ferromagnetic material or other material which is capable of being magnetized and which distorts the flux :lines when brought into a magnetic field.

It is an object of the invention to provide an improved magneticmate-rial detector system, and more especially to provide such a system which is more sensitive, lighter in weight, and that operates on less current, and which is effective over a wider temperature range.

Another object is to combine such a detector system in an elevator control system having vanes at spaced locations along the elevator shaftway for inductively operating the control system. As applied to an elevator, this invention simplifies the control by using amplified inductively-altered signals from the vanes to operate heavy duty power relays, thus eliminating the necessity for the intermediate sensitivity relays that are used on inductive controls of existing elevator system-s.

Another advantage in an elevator control system that is obtained with this invention is the increased selectivity which permits wider manufacturing tolerances, thus redu-cing the cost of the equipment; but a more important advantage of the increased sensitivity is that the response is faster and therefore more satisfactory. for high speed elevators. Experience has shown that with this invention the control can go from pick up to drop out of the main power relay within only one-sixteenth inch of vane motion relative to the elevator car.

The invention will be described as applied to an elevator control system having controls that operate in response to the movement of the elevator car to the vicinity of the ferromagnetic metal vanes located at predetermined locations along the shaftway; but it will be understood that is can be used for detecting the presence of ferromagnetic metal in other applications within the scope of the claims.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing forming a part thereof, in which like reference characters indicate corresponding parts in all the views FIGURE 1 is a diagrammatic view of an elevator shaf-t with control and operating mechanism made in accordance with this invention;

FIGURE 2 is a sectional view taken on the line 2--2 of FIGURE 1;

FIGURE 3 is a fragmentary side elevation showing the location of the detector and amplifier assembly on top of an elevator car and illustrating the manner in which it is operated from the vane along the elevator shaft;

FIGURE 4 is a fragmentary top plan view of the apparatus shown in FIGURE 3; and

FIGURE 5 is a wiring diagram [for the elevator shown in the other views.

FIGURE 1 shows an elevator car which travels up and down in a shaftway 12 past various floors 14, there being four such floors illustrated in FIGURE 1.

The elevator car 10 has shoes 16 that run along tracks 18 attached to opposite side walls of the shaftway 12. There are

vanes

21 and 22 located along the shaftway 12 at different locations corresponding to the floors at which the elevator is intended to stop. These vanes are carried by brackets 24 attached to one of the rails 18 and the brackets 24 are adjustable up and down along the rails to change the positions of the

vanes

21 and 22 lengthwise of the shaft. The vanes 21 are distributed along the shaftway 12 in a straight line and the vanes 22 are distributed along the shaftiway in a straight line which is spaced from but parallel to the line of the vanes 21. One set of vanes controls the elevator when the car is moving up, and the other set of vanes control the elevator when the car is moving down.

A detector assembly 26 is attached to the elevator car 10 and moves up and down in the shaftway as a unit with the car. -In the diagrammatic illustration of FIGURE 1, the detector assembly 26 is located on top of the elevator car 10 and it is located in position to pass close to the rows of

vanes

21 and 22.

The elevator car 10 has a cable 31 attached to the elevator car 10 at one end and at the other end to a control means 40 which is connected to a source of power and to a hoist motor 42 which operates a cable drum 44 at the head of the shaftway 12. A hoist cable 46 is connected with the elevator car 10, and this hoist cable winds on the drum 44. There is also a brake 47 for stopping and holding the car 10, this brake 47 being also controlled from the control mechanism 40.

The mechanism thus far described is conventional and the diagrammatic showing is simplified for clearer illustration. It will be understood that the elevator system may be an operator-controlled system or an automatic one. The only part of the control mechanism that need be illustrated and described, for a complete understanding of this invention, is the part for transmitting a signal from the detector assembly 26 to the control mechanism 40 from either the up vanes or the down vanes.

FIGURES 3 and 4 show the detector assembly 26. This includes a housing 51 with three

vanes

53, 54 and 55 extending from one side of the housing 51 in parallel relation with one another.

There is a primary coil 57 carried on the center vane 54. There is a secondary coil 58 carried by the vane 53; and another secondary coil 59 carried by the vane 55. The coils are spaced from one another and from adjacent vanes by sufficient space to permit the

vanes

21 and 22 to enter the space between the coils as the elevator car travels up or down in the shaftway.

The primary coil 57 and the secondary coil 58 constitute a transformer and alternating current in the primary coil 57 sets up an alternating magnetic field in which the secondary coil 58 is located. When a vane 22 is located between the

coils

57 and 58, the vane 22 distorts the magnetic field and short circuits much of the field so that lines of force reaching the secondary coil 58 are great- 1y reduced and the alternating current in the circuit of the coil 58 becomes very small. Thus a change in signal strength is produced in the circuit of the secondary coil 58 whenever the ferromagnetic metal vane 22 moves into the magnetic field between the primary coil 57 and the secondary coil 58.

Likewise, the primary coil 57 and the secondary coil 59 form a transformer and whenever one of the vanes 21 moves into the magnetic field of this second transformer, the amount of current induced in the secondary coil '59 is very much reduced and a change in signal strength is thus imparted to the circuit of the secondary coil 59. It is one of the advantages of this invention that the

coils

57, 58 and 59 may be very small and the currents flowing in their circuits may be also very small.

It is a feature of the preferred embodiment of the invention that the amplifier circuit in the housing 51 is located close to the

detector coils

58 and 59 so that the signals from these coils can be amplified without passing through any long conductors between the

coils

58 and 59 and the amplifying transistors. The advantage of this feature is that the picking up of transient currents in the conductors is avoided. Elevator cars often pass close to electrical disturbances which may be located on the various floors of a building and if long conductors are used to transmit the relatively weak signals from the

coils

58 and 59 to the amplifiers, stray signals are picked up which adversely affect the reliability and operation of the invention. It the amplifier circuit is not located close to the directed signal coils, then it is necessary to use larger coils and heavier current flows and signals in order to accomplish the same purpose as this invention.

The currents to operate the amplifier in the housing 51 and to energize the primary coil 57 are supplied by conductors in the cable 31 and current to the relays in the control mechanism 40 is supplied through

other conductors

82 and 82 in the cable 31.

FIGURE is a wiring diagram illustrating the principle and the operation of the invention. The coil 58 is connected by a conductor 68 to the base of a transistor 70. The emitter of this transistor is connected by a conductor 72 with the other side of the coil 58 and is also connected with a resistor 74 and with the base of a second transistor 76. There is, therefore, a first circuit leading from the coil 58, through the conductor 68, transistor 70, and conductor 72 back to the coil 58.

There is a second circuit leading from a conductor 78 through a diode 80 to the emitter of the second transistor 76 and from the collector of the transistor 76 through a conductor 82 in cable 31 to an actuator coil 84 of a relay 86 located in control mechanism 40. The contacts 88 of the relay 86 are illustrated diagrammatically in the wiring diagram, it being understood that energizing of the coil 84 causes the contact 88 of the relay 86 to come together and thus close the relay.

This second circuit also includes a conductor 90 which joins the conductor 72, the base of transistor 76 the negative terminal of capacitor 96, the resistor 74 and a conductor 92, in cable 31 which connects with the negative side of the direct current power line 100.

There is a capacitor 96 connected across the emitter and collector of the first transistor 70 and connected in parallel with the diode 80 and the bare-emitter junction of the second transistor 76.

As long as there is no magnetic material between the primary coil 57 and the secondary coil 58, an alternating current is induced in the secondary coil 58 and this current flows in the first circuit of the amplifier, the current being large enough to maintain the first transistor 78 in a conducting condition during the forward half cycles even though this transistor 70 has a normal bias to its 011 condition, that is to a condition in which it does not conduct any current from emitter to collector when no signal is supplied from coil 58.

When the magnetic field of the secondary coil 58 is disturbed, and the current in the first circuit drops below the value which will maintain the transistor 78 conducting, then no further current flows through the first transsistor 70 until the disturbance in the magnetic field of the coil 58 is removed and the power supply in the first circuit is sufficient to again cause the first transistor 70 to become conductive.

The conductor 78 is connected with the positive side of a direct current power line 108, and the conductor 92 is connected with the negative side of the power line. This power supply cannot fully charge the capacitor 96, however, as long'as the first transistor 70 becomes conducting on each half cycle of its alternating current input signal because the capacity of the capacitor 96 is made sufficient in relation to the value of resistor 74 so that it cannot fully charge on the non-conducting half cycle of the alternating current in the first circuit and each time that the transistor 70 becomes conductive on one half of its alternating current signal supply, the transistor 78 short circuits and discharges partially the capacitor 96.

The diode is used to obtain a reverse bias on the second transistor 76 while the first transistor 70 is conducting and to thus maintain the second transistor 76 in a cut off (non-conducting) condition so that no current in the second circuit can flow to the actuating coil 84 of the relay 86-. However, when the current flow in the first circuit becomes so small that the first transistor 70 becomes non-conducting, then the capacitor 96 is no longer short cirouited at each half cycle of the alternating current from the coil 58 and the capacitor 96 charges to a sufiiciently high potential to cause a forward bias to exist on the transistor 76 emitter base junction. This action causes the second transistor 76 to go to saturation and conduct current to the conductor 82 in cable 31 and to the coil 84 of the relay 86 in control mechanism 40, thus energizing the relay and causing it to close. This supplies power to the conductor 62 which connects with one contact of the power relay 86 andthe conductor 62.

The other secondary coil 59, shown in FIGURE 5, controls a circuit similar to that controlled by the coil 58. Corresponding parts are indicated by th same reference characters with a prime appended.

The relay 86' operates contacts 88' to supply power to the conductor 61. The two

conductors

61 and 62 from the relay circuits operate the portion of the control mechanism which control up movement and down movement, respectively, of the elevator car.

There are other diodes 106 and 106' connected between the conductors 82 and 82' with the center of this dual diode connected by a conductor 108 leading to the conductor 92 on the negative side of the power line 100. The purpose of this dual diode is to protect the transistors 76 and 76' from any inductive surge from the relay actuating coils 84 and 84' when the magnetic fields of these coils 84 and 84' are decaying. Thus the diodes 106 and 106' act as a damper.

A capacitor 110 connected between the

conductors

78 and 92, in combination with a diode 112 connected in series with the conductor 78 serve as a transient suppressor and the diode 112 also protects the apparatus against polarity reversal.

The invention has been illustrated and described as applied to an elevator system where the apparatus detects the presence of ferromagnetic metal vanes at various locations along the shaftway, but it will be understood that the detector and amplifying equipment can be used for other situations where it is desirable to detect the presence of magnetic material. The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made, and some features can be used in difierent combinations without departing from the invention as defined in the claims.

What is claimed is:

1. A detector system for magnetic material including (a) a first circuit,

(b) means producing an alternating current in the first circuit,

(c) a coil in said first circuit in a magnetic field which is distorted by presence of magnetic material to reduce the flow of current in said first circuit,

(d) a first transistor in the first circuit normally biased to be non-conducting when current in the first circuit is below a given value,

(c) a capacitor connected across the first transistor in parallel with said transistor,

(f) a second circuit connected with a source of power, part of the second circuit being connected in parallel with the first transistor and the capacitor,

(g) a second transistor in the second circuit, at least a portion of the second transistor being in the part of the second circuit that is connected in parallel with the transistor of the first circuit,

(h) a power relay for a circuit that is to be controlled,

said relay having an actuating coil in the second circuit,

(i) and means in the second circuit biasing the second transistor in an off condition when the first transistor is conducting, the capacitor being of suificient capacity to avoid fully charging on any half cycle of the time that the first transistor is conducting as the result of flow of alternating current in the first circuit, and the capacitor having a potential, when charged more fully during a plurality of cycles when the first transistor is not conducting, to overcome the means in the second circuit biasing the second transistor in an off condition whereby the sec-0nd circuit becomes conducting and energizes the power relay when the first transistor becomes non-conducting as the result of decrease in the alternating current in the first circuit, characterized by the coil in the first circuit being a secondary coil of a transformer, and the means for producing an alternating current in the first circuit being a primary coil of the transformer that produces the magnetic field in which the secondary coil is located, and characterized by the primary and secondary coil-s being located on an elevator car that travels up and down in a shaftway, vanes of ferromagnetic material at spaced locations along the shaftway in position to pass between the primary and secondary coils as the elevator car travels past the vanes, a motor for the elevator car, and an electric circuit for the motor controlled by said power relay.

2. The detector described in claim 1 characterized by there being two detector systems on the elevator car, and two sets of van-es in the shaftway, each set of vanes having its vanes in line for cooperation with a different one of the detector systems, the power relay of one of the detector systems controlling operation of the elevator when the car is going up and the power relay of the other detector system controlling operation of the elevator when the car is going down.

3. In an elevator system in which an elevator car travels up and down in a shaftway, and there is a motor for the elevator car and there are ferromagnetic metal vanes located along the shaftway at different levels in the shaftway corresponding to stations at which the elevator car stops,

(a) combination with said vanes of control means,

(b) including a detector carried by the car in position to pass close to the vanes at the different locations as the car moves up and down in the shaftway,

(c) means for producing an electric signal in the detector as the detector passes close to said vanes,

(d) an amplifier for the signal,

(e) a relay for controlling the supply of power to the motor,

(f) the relay having an operating coil, and

(g) a circuit in which the operating coil is located and to which the amplified signal is supplied to energize the coil to operate the relay.

4. The elevator system described in claim 3' characterized by the detector being located at a side of the elevator car that is closeto the vanes,

(a) conductors connecting the detector with the am- (b) the amplifier being located immediately adjacent to the detector so that said conductors are short to avoid pick-up of transient currents in the conductors.

5. The elevator system described in claim 3 characterized by the detector including a transformer coil having a magnetic field that is distorted by the vanes in the shaftway.

6. The elevator system described in claim 3 characterized by the detector including a transformer having a primary coil and a secondary coil spaced from one another, the space being in line with the vanes so that the vanes pass between the coil and shield the secondary coil from the primary coil during travel of the car along the shaftway.

References Cited by the Examiner UNITED STATES PATENTS 2,778,978 1/1957 Drew 317-149 X 2,859,402 11/1958 Schaeve 317-123 2,874,806 2/1959 Oplinger 187-29 3,199,630 8/1965 Engle et al. 187-29 ORIS L. RADER, Primary Examiner.

T. LYNCH, Assistant Examiner.

Claims

1. A DETECTOR SYSTEM FOR MAGNETIC MATERIAL INCLUDING (A) A FIRST CIRCUIT, (B) MEANS PRODUCING AN ALTERNATING CURRENT IN THE FIRST CIRCUIT, (C) A COIL IN SAID FIRST CIRCUIT IN A MAGNETIC FIELD WHICH IS DISTORTED BY PRESENCE OF MAGNETIC MATERIAL TO REDUCE THE FLOW OF CURRENT IN SAID FIRST CIRCUIT, (D) A FIRST TRANSISTOR IN THE FIRST CIRCUIT NORMALLY BIASED TO BE NON-CONDUCTING WHEN CURRENT IN THE FIRST CIRCUIT IS BELOW A GIVEN VALUE, (E) A CAPACITOR CONNECTED ACROSS THE FIRST TRANSISTOR IN PARALLEL WITH SAID TRANSISTOR, (F) A SECOND CIRCUIT CONNECTED WITH A SOURCE OF POWER, PART OF THE SECOND CIRCUIT BEING CONNECTED IN PARALLEL WITH THE FIRST TRANSISTOR AND THE CAPACITOR, (G) A SECOND TRANSISTOR IN THE SECOND CIRCUIT, AT LEAST A PORTION OF THE SECOND TRANSISTOR BEING IN THE PART OF THE SECOND CIRCUIT THAT IS CONNECTED IN PARALLEL WITH THE TRANSISTOR OF THE FIRST CIRCUIT, (H) A POWER RELAY FOR A CIRCUIT THAT IS TO BE CONTROLLED, SAID RELAY HAVING AN ACTUATING COIL IN THE SECOND CIRCUIT, (I) AND MEANS IN THE SECOND CIRCUIT BIASING THE SECOND TRANSISTOR IN AN OFF CONDITION WHEN THE FIRST TRANSISTOR IS CONDUCTING, THE CAPACITOR BEING OF SUFFICIENT CAPACITY TO AVOID FULLY CHARGING ON ANY HALF CYCLE OF THE TIME THAT THE FIRST TRANSISTOR IS CONDUCTING AS THE RESULT OF FLOW OF ALTERNATING CURRENT IN THE FIRST CIRCUIT, AND THE CAPACITOR HAVING A POTENTIAL, WHEN CHARGED MORE FULLY DURING A PLURALITY OF CYCLES WHEN THE FIRST TRANSISTOR IS NOT CONDUCTING, TO OVERCOME THE MEANS IN THE SECOND CIRCUIT BIASING THE SECOND TRANSISTOR BECOMES AN OFF CONDITION WHEREBY THE SECOND CIRCUIT BECOMES CONDUCTING AND ENERGIZES THE POWER RELAY WHEN THE FIRST TRANSISTOR BECOMES NON-CONDUCTING AS THE RESULT OF DECREASE IN THE ALTERNATING CURRENT IN THE FIRST CIRCUIT CUIT, CHARACTERIZED BY THE COIL IN THE FIRST CIRCUIT BEING A SECONDARY COIL OF A TRANSFORMER, AND THE MEANS FOR PRODUCING AN ALTERNATING CURRENT IN THE FIRST CIRCUIT BEING A PRIMARY COIL OF THE TRANSFORMER THAT PRODUCES THE MAGNETIC FIELD IN WHICH THE SECONDARY COIL IS LOCATED, AND CHARACTERIZED BY THE PRIMARY AND SECONDARY COILS BEING LOCATED ON AN ELEVATOR CAR THAT TRAVELS UP AND DOWN IN A SHAFTWAY, VANES OF FERROMAGNETIC MATERIAL AT SPACED LOCATIONS ALONG THE SHAFTWAY IN POSITION TO PASS BETWEEN THE PRIMARY AND SECONDARY COILS AT THE ELEVATOR CAR TRAVELS PAST THE VANES, A MOTOR FOR THE ELEVATOR CAR, AND AN ELECTRIC CIRCUIT FOR THE MOTOR CONTROLLED BY SAID POWER RELAY.