US1909094A - System of control - Google Patents

Description

May 16, 1933. CLAYTQR 1,909,094

SYSTEM OF CONTROL Filed May 25, 1925 f /gl.

WITNESSES: INVENTOR Edward M. C/ayfor: BY

4 ATTORNEY Patented May 16, 1933 UNITEDv STATES PATENT OFFICE EDWARD Mr CLAYTOR, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

SYSTEM OF CONTROL Application filed May 25, 1925. Serial No. 32,538.

My invention relates to motor-control systems,and it has particular relation to systems employed in connection with elevators, hoists and the like.

One object of my invention is to provide means for effecting accurate stopping of an elevator independently of the skill of the operator.

Another object of my invention is to provide a system whereby accurate stopping of an elevator is effected without the use of devices that are mechanically operated in accordance with the movement of the elevator.

It has been common practice to employ mechanically-operated switches for securing accurate elevator stops, but such means is open to a number of objections, among which are noise occasioned by such mechanical arrangement and the necessity for maintaining proper adjustment of such devices.

In accordance with my invention, I employ, preferably, a variable-voltage system of motor control and remote-control operating means, such as a car switch located within the elevator car. This switch serves as means for initiating the operation of the system and, in addition thereto, I employ a transformer carried by the car with which a plurality of stationary magnetizable members, or armatures, cooperate to control the slow down and stopping of the car. One of these .armatures is located adjacent to each landing. The magnetizing efiect of the transformer on the car, with respect to the corresponding armature .in the hatchway, is such as to effect the operation of relays that are located on the control panel in the elevator machine room.

In accordance with this system of control, I am able to eliminate relays and other electroresponsive devices from the car, or from points adjacent thereto in the hatchway, all such devices being now mounted in the elevator machine-room.

My invention will be described in connection with the accompanying drawing, in which Figure 1 is a diagrammatic representation of circuits and apparatus embodying my invention, and

Fig. 2 is a similar view of a modification of circuits that may be employed in connection with the system of Fig. 1.

Referring to Fig. 1, a hoisting motor 1, having an armature 2 and a separately-excited field-magnet winding 3 is operatively connected to a hoisting drum or sheave 4, in a familiar manner, for operating a car or cage 5. The hoisting motor is supplied with energy from a generator 6 having an armature 7 that is connected in a loop circuit with the motor armature 2, in a manner that is common to variable-voltage systems. A separately excited field-magnet winding 8 and a series winding 9 on the generator are preferably cumulatively-compound-wound, the series field winding being of suitable strength to insure the desired motor-speed regulation.

A heavy load current drawn by the motor increases the generator field excitation,

whereas a reduction in motor current or a reversal of motor current effects a corresponding reduction in generator voltage to maintain a substantially constant motor speed, independently of varying load conditions.

The separately excited field winding 8 is controlled by reversing switches 11 and 12 having operating coils 13 and 14 remotely controlled by the cam-type car switch 15. Interlock contact members 16 and 17 are mechanically operated by the reversing switches 11 and 12 and provide holding circuits therefor, as hereinafter set forth. The switches 11 and 12 are preferably mechanically interlocked by means of a pivotally mounted bar 18, of a familiar type whereby it is impossible to effect simultaneous closure of the switches. A separate source of direct-current excitation is provided, comprising conductors 21 and 22. Any suitable constant-speed driving means may be employed for operating the generator armature 7, such as the illustrated induction motor 23.

In accordance with modern practice, an alternating-current source of energy is commonly available and is preferably employed for the operation of elevators, and more particularly for the variable-voltage type.

In accordance with my invention, I utilize a source of alternating current comprising conductors 24, 25 and 26 for operating the induction motor 23 of the motor-generator set and for supplying excitation to a transformer 27 of the constant-current ty e which is located on the elevator car 5. second transformer 28, of the constant-potential type is preferably located in the elevator mac ine-room ad acent to other switchlng apparatus.

he secondary windings 31 and 32 of the respective transformers are connected in a closed circuit and in such relation that the voltage induced in the winding 31 opposes that which is induced in the winding 32. In the circuit of the secondary transformer windings is connected a plurality of operating coils 33 and 34 for controlling field relays 35 and 36. Relay 35 is ada ted to control generator field resistor 37 an relay 36, when deenergized, partiall completes a circuit for the generator field-winding 8, comprisin resistor 37 and the one or the other 0 the vreversin switches 11 and 12. The secondary win ings 31 and 32 and the relay coils 33 and 34 controlled thereby are energized only when the car switch 15 occupies its inoperative or off position, in which carswitch members 38 are closed.

Each landing is provided with a magnetizable member such as the illustrated members 41 and 42, each member bein adapted to partially demagnetize the trans ormer 27 on account of the leaka e flux that passes from the transformer t rough the corresponding magnetizable member as the elevator car approaches a landing. That is to say, the magnetizable members 41 and 42 function as magnetic shunts to shunt a portion of the flux away from the core of the secondary winding of the transformer.

Assuming the apparatus in its illustrated and inoperative condition, the car 5 will move downward when the car switch 15 is actuated in a clockwise direction, whereb the switch members 43 and 44 are close A circuit is thereby established for reversingswitch coil 13 extending from line conductor 21, through conductor 45, switch members 43, conductor 46, and coil 13, to line conductor 22. A holding circuit for coil 13 is established by the operation of switch 11, this holding circuit being independent of car switch 15 and extending from line conductor 21 through conductor 45, interlock 48, of relay 36 conductor 49, interlock 16 of switch 11 conductor 46, and coil 13 to line conductor 22. While the car switch 15 is operative, the switch 38 is open and the relays 35 and 36 are inoperative, the circuit, comprising transformer- windings 31 and 32, being deenergized by such opening of switch 38.

If it is desired to stop the elevator at the floor corresponding to the magnetizable member 42, the car switch 15 is returned to its off position at any time after leaving the next adjacent landing. The secondary windings 31 and 32 become energized upon the closure of switch 38, but, being in opposition to each other, they are ineffective to operate the relays 35 and 36.

However, in the downward movement of the elevator, as the transformer 27 passes adjacent to the magnetizable member 42, a portion of the flux of the transformer is deflected through the member 42 as it enters the field of the transformer. An unbalanced voltage condition is now induced on account of the weakened effect of winding 31 and a sufficient current flows from transformer Winding 32 to effect successive operation of relays 35 and 36. The relay coil 33 is'adapted to open relay 35, prior to the opening of relay 36, thereby inserting resistor 37 in circuit with the generator field-winding 8 to effect a corresponding reduction in the speed of the hoisting motor 1. The elevator is thus slowed down to a predetermined deee and, when at the proper floor position, the effect of the magnetizable member 42 renders the relay coil 34 effective to open relay 36, thereby opening the interlock 48, to deenergize reversing switch coil 13 and stop the motor. the cam and the transformer at any floor level, are as illustrated in the drawing.

Any well known means may be employed for insuring successive operation of relays 35 and 36, such as providing coil 34 with more turns than coil 33, or varying the weights of the movable members.

It will be evident that the magnetizable members, or magnetic shunts, 41 and 42 and the magnetic circuit of transformer 27 may readily be adapted to effect the initial slow down at an desired point or car travel, and, likewise, t e length and shape of the shunt should be such as to insure that the car will stop accurately with res ect to any floor or landing. That is, the e ect of the shunt is to gradually deflect magnetic flux from the transformer in accordance with the motion of the elevator car to insure the automatic control described.

It should also be noted that car-switch members 44 are connected to shunt resistor 37, thereby roviding manual control of the generator eld excitation and of the car speed during the starting period. It becomes unnecessary, however, to manually slow down the elevator, in the customary manner, upon approaching a landing, for the reason that slow-down is effected automatically, as previously described after the car switch is centered.

Reversal of the direction of car travel is, of course, effected by a counter-clockwise movement of the car switch 15, to close the switch members 53, whereupon operating coil 14 of reversing switch 12 becomes ener- The relative positions of l gized and for which a holding circuit is established through the interlock 17, in the same manner as provided for the upward direction of travel. The holding circuit for coil 14 likewise traverses the interlock 48, attached to relay 36; this relay, therefore, being effective to control either of switches 11 and 12, as will. be readily understood.

While I have described the preferred form of my invention, I have also illustrated, in Fig. 2, a modification thereof wherein only one transformer is employed. In accorda nce with this arrangement, the secondary winding 31 is normally energized, whereby voltage is supplied to relays 35 and 86, which are closed when the elevator is operating between landings and under the control of the operator.

In accordance with this modification of my system, the secondary winding 31 is gradually deenergized by means of the m agnetizable cams, and, as the elevator approaches the desired landing, the relays 35 and 36 are successively opened to effect slowdown and stopping, in a manner corresponding to that previously set forth. he control system and apparatus employed are otherwise as described in connection with Fig. 1, and it is believed to be unnecessary to further describe the operation.

It will be evident that any suitable source of alternating-current supply may be utilized, whether single-phase or polyphase. The direct-current source of energy may comprise a direct-connected exciter gener tor, or any other desirable means.

My system is not necessarily limited to variable-voltage control; in fact, any system insuring a substantially constant slow speed of operation for effecting accurate landings may be employed.

In order to provide means for compensating for variations in the adjustment of brakes or the rapidity with which the car 'decelerates when slow down is initiated, the

position of transformer 27 may be adjusted vertically. Such manual adjustment serves as a convenient means for securing the proper position with respect to each floor, without the necessity of adjusting the magnetic shunt members, individually, after the original setting is determined.

Modifications of my invention will naturally occur to one skilled in the art, and I desire, therefore, that my invention shall be limited only in accordance with the scope of the appended claims.

I claim as my invention:

1. The combination with an elevator motor and manual controlling means therefor, of e'lectro-responsive means for controlling the motor, a transformer carried by the ele vator car for controlling said electro-responsive means, and means external to said car for partially demagnetizing said transformer.

2. The combination with an elevator motor and manual controlling means therefor, of eleotroresponsive means for controlling the motor, a translating device movable in accordance with the movement of the elevator for controlling said eleotroresponsive means, a second translating device cooperating with the first-named device for controlling said electroresponsive means, and a plurality of demagnetizing members adjacent to the elevator car for selectively controlling the effect of said translating devices.

3. The combination with an elevator car and a hoisting motor therefor, of manually operable means for initiating the operation of the motor, means for automatically regulating the speed of said motor under varying load conditions, eleotroresponsive means for insuring the continued operation of said motor when said manually operable means is rendered ineffective, a transformer on the car for energizing said eleotroresponsive means, and a magnetizable armature in the hatch vay for effecting a gradual demagnetization of said transformer in accordance with the movement of said car.

4. The combination with an elevator motor and a variable-voltage generator therefor, of eleotroresponsive means for varying the generator field excitation, a transformer carried by the elevator car for controlling said electroresponsive means, and means external to said car for partially demagnetizing said transformer to partially deenergize said generator.

5. The combination with an elevator motor and a variable-voltage generator there for, of eleotroresponsive means for varying the generator field excitation, a transformer carried by the elevator car for controlling said electroresponsive means, and a magnetizable armature in the hatchway for effecting a gradual demagnetization of said transformer to efiect a reduction in said generator field excitation.

6. In an elevator-control system, an elevator operable past a floor, an elevator motor therefor, a source of power, means for controlling the supply of power to said motor to move said motor, means operable by actuation of said controlling means for maintaining said supply, and means operable by approach of said elevator to said floor for releasing said maintaining means, said releasing means including a circuit, a pair of transformers connected for normally impressing equal voltages of opposite polarities on said circuit, and means operable in correspondence with movement of said elevator for varying the value of voltage impressed by one of said transformers, and switch means responsive to the current in said circuit.

7. In an elevator-control system, an eletrolling the supply 0 vator operable past a floor, an elevator motor therefor, a source of power, means for controlling the supply of power to said motor to move said motor, means operable by actuation of said controlling means for maintaining said supply, and means operable by approach of said elevator to said floor for releasing said maintaining means, said releasing means including a normally open circuit, a pair of transformers connected for normally impressing equal voltages of opposite polarities on said circuit, means operable in correspondence with movement of said elevator for varyin the value of voltage impressed by one 0 said transformers, switch means responsive to the current in said circuit, and means manually operable to one position for actuating said controlling means to start said motor, and operable to another position for closing said circuit.

8. In an elevator-control system, an elevator operable past a floor, an elevator motor therefor, a source of ower, means for conpower to said motor to move said motor, means operable by actuation of said controlling means for maintaining said supply, and means operable by approach of said elevator to said floor for releasing said maintaining means, said releasing means including a normally open circuit, a pair of transformers connected for normally impressing equal voltages of opposite polarities on said circuit, means operable in correspondence with movement of said elevator for varying the value of voltage impressed by one of said transformers, switch means responsive to the current in said circuit, and means for closing said circuit.

9. In an elevator-control system, two relatively movable members, including an elevator and a hatchway in which said elevator operates past a floor, a motor therefor, a source of power, means for controlling the supply of power to said motor to move said motor, means operable by actuation of said controlling means for maintaining said supply, and means operable by approach of said elevator to said floor for releasing said maintaining means, said releasing means including a normally open circuit, a pair of transformers connected to impress equal voltages of opposite polarities on said circuit, one of said transformers being carried by one of said relatively movable members, means carried by the other of said members for modifying the magnetic characteristics of said carried transformer when said carried transformer and modifying means are brought adjacent each other, to thereby vary the voltage impressed by said carried transformer, switch means responsive to the current in said circuit for actuating said releasing means, and means for closing said circult.

10. In an elevator system, an elevator car operable in a hatchway, a relay associated with said system, and means to cause an operation of said relay when said car reaches a predetermined point in said hatchwa comprising a plurality of energizable win ings mounted on said car in inductive relation, and means mounted in said hatchway and disposed to vary the inductive coupling between said windings when said car approaches said point.

11. In an elevator system, an elevator car operable in a hatchway, a control device having a winding associated with said system,

a plurality of energizable windings mounted on said car in inductive relation, means mounted in said hatchway and disposed to vary the inductive coupling between said windings when said car reaches a predetermined point in said hatchway, and circuit connections between one of said energizable windings and the winding of said control device.

12. In an elevator system, an elevator car operable in a hatchway, a relay associated with said system, and means to cause an operation of said relay when said car reaches a predetermined point in said hatchway comprising a plurality of windings mounted on said car in inductive relation, means for exciting said windings with an alternating current, means mounted in said hatchway and disposed to vary the inductive coupling between said windings when said car approaches said point, to thereby vary the current in one of said windings, and means to render said relay responsive to said current variation.

13. In a control s stem for an elevator car operable past a oor, motive means for said car, and means to control said motive means to effect the stopping of said car at said floor comprising a plurality of evergizable windings, means for mounting said windings on said car in inductive relation, and means mounted in said hatchway and disposed to vary the inductive coupling between said windings when said car reaches a predetermined point in said hatchway adjacent said floor.

14. In a control system for an elevator car operable past a floor, motive means for said car, and means to control said motive means to effect the stopping of said car at said floor comprising a plurality of energizable windings, means for mounting said windings on said car in inductive relation, means for exciting said windings with alternating current, means mounted in said hatchway and disposed to vary the inductive coupling between said windings and a relay controlled in accordance with the current in one of said windings.

15. In a control s stem for an elevator car operable past a oor, motive means for said car, and means to control said motive means to effect the stopping of said car at said floor comprising a plurality of energizable windings, means for mounting said windings on said car in inductive relation, means for exciting said windings with alternating current, means mounted in said hatchway and disposed to vary the inductive coupling between said windings, to thereby vary the current in one of said windings, and a relay responsive to said current variation.

In testimony whereof, I have hereunto subscribed my name this 14th day of May,

EDWARD M. OLAYTOR.

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