US1043036A - Controlling system for electric hoists. - Google Patents

Description

FLT. SMITH.

CONTROLLING SYSTEM FOR ELECTRIC HOISTS.

' APPLICATION FILED APR-5, 1911.

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APPLICATION FILED APR. 5. 1911.

2 SHEETS-SHEET 2,

Patented 0011.29, 1912.

v UNITED STATES PATENT OFFICE.

FRANK I. SMITH, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOIR. TO OTIS ELEVATOR COMPANY, 'OFJERSEY CITY, NEW JERSEY, A CORPORATION 01 NEW JEBSET.

To all whom it may concern:

CONTROLIIING SYSTEM FOR ELECTRIC HOISTS.

Be'it known that I, FRANK I. S ITH, a

. citizen of the United States, residing at of motors used for Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Controlling Systems for Electric Hoists, of which'thefollowing is a specification.

-- I My invention relates to motor controlling apparatus, and particularly to the control furnace hoists.

()ne object of my invention is automatically to reduce the speed of the hoisting car or bucket as the latter approaches its limits of travel.

A further objeotis the provision of means for independently controlling and regulat-,

able toefi'ect a slow-down of the driving. motor before applying the. brake to stop the machine. Inthe familiar case of vertical riseelevators such as are used in modern oflice buildings for conveying passengers, etc, plOVlSlOIllS made for slowing down the motor just previous tostopping so that the elevator car will gently and smoothlystop at any desiredt landing without jar or dis-v comfort to the passengers. .In order to effect this slow down before stopping where the elevator'is operated by an electric motor it iscustomary to employ one or more electro-miignets which are arranged to be: op-

both, thereby causing the motor torun at reduced speed just before a stop ismade. Vhile such an arrangementis widely used and its operation answers very wellfwhere the elevator is of the vertical rise there are certain difficulties encountere 'wh operating skips for blast eratedat the proper time to vary the-motorcurrent or increase. the field strength or that the tendency en it is desired it() use such an arrangement for, effecting :a :slow *down of the hOISt'HIQ motor Specification of Letters Patent. f tg t o n 29, 1912, Application filed April 5, 1911 Serial No; 619,061.

lower limit of travel, and seldom if ever stopped at tin-intermediate point. Further .more it has been found necessary to effect a diflerent slow-down .at the top of the incline than that at the bottom, for the reason that -in a furnace hoist, the empty bucket may be rapidly slowed down near the bottom of the hoist, but the heavily loadedfbuck etat the top of the hoist must be slowed. down much more carefully .and slowl the bucket may swing violently rom' side to side and this has been known to do great damage; moreover, much time might be lostin waiting-for the oscillations to die out so thatthe bucket can be centered ,over the hell of the furnace.

While, as before stated, the usual slowdown for vertical rise elevators is the same no matter where the car may be or in what direction it is traveling, it is. readily seen that in a blast furnace hoist provision should be made seas to effect a different slow down at the top and bottom limits. My invention contemplates means for doing this in a simple and effective manner an furthermorein a way whichwill be entirely automatic and dependent upon the load and speed of the bucket.

Referring to Fig. 1, Adesi nates a blast furnace which supplied wit ore, etc, at the top ,iafter the usual manner lg means of a bucket B which is suspended. om a carriage H adapted to travel over the inclined rails T.

zontaL. S designates the power house which contains the motor M and the controlling switches E and C. F is the driving cable otherwise which is secured to the carriage and leads I over suitable guide sheaves I and D and is driven by the motor M. This arrangement I of inclined hoist rails is common to the ma- Qjonity of blast. furnaces and it will be seen for the bucket to swing due to .a change in speed at the .lower curve isnnotinearly so great as'it wouldfbe at the upper curved portion. Moreover, while the portion of the rail from the summit of the curve to the furnace may be substantially horizontal, its general direction is downward the bell; the effect of this isthat not only must the skip be properly retarded at the summit in its ascent up the incline, so as to have it eventually stop and center over the bell, but the.skip must be suitably held back if necessary against any tendency to accelerate after it has passed the summit or curve. only the differences of conditions at the top and bottom of the hoist, but the differences as to control, and the difficulties encountered in securing a perfected control at both .top and bottom. For this reason I have found that it is very desirable to effect a difl'erent speed reduction at the top of the hoist than that best adapted for the bottom and I will now describe the apparatus and electrical circuits associated therewith whereby I effeet this speed reduction.

Referring to Fig. 2, E designates a handswitch for starting, stopping, reversing and accelerating the motor by manual control. C is an automatically operated controlling switch which effects the proper speed reduction and causes the motor to stop at its' extreme limit of travel in either direction. J designates the usual brake which is used to stop the motor when the same is disconnected from the main line. B and R are the motor starting and reversing switches and L is a multiple magnet which controls the starting resistance 10 and series field 20.

N is a relay which controls a circuit to the resistance 50 and extra field 40. 30 designates the shunt field. 60, 70, 80 and 90 are multiple magnets which control the resistanee 50. With this general description, I will now describe each part in detail, and point out the various electrical circuits and their action.

The reversing switches R and R are similar in construction and each comprises a magnet winding such as 2 which is adapted, when energized, to raise a core 3 and connected rod 4. The latter carries a pair of insulated members or disks 5 and 6 to which are attached contacts 8, 11 and 13, 15, respectively. The contacts 8 and 11 are adapted to be raised into electrical engagement with stationary contacts 7 and 9, 12, respectively, while the contacts 13 and 15 are normally in engagement with stationary contacts 14 and 16, respectively, and are raised out of contact therewith whenever the magnet winding 2 is energized. The acceler- All of which go to accentuate not- .nears the bottom of the incline.

controlled by the speed of the motor to short circuit more or less of the resistance 50. The magnets and are operated when the loaded bucket approaches the top of the incline, while the magnets -and operate in a similar manner when the empty bucket The.construction of these magnets may be widely varied but it is desirable to arrange the contacts controlled thereby in such manner that each one will operate at a certain given strength of magnetism induced by the magnet winding. One way of doing this is to adjust the air gap of each contact carrying armature such as is shown in Patent 677,359, issued to John D. Ihlder on July 2, 1901, entitled Electromagnet. It is not considered necessary to illustrate this magnet construction since it is well known in the art and requires no further description. The automatically operated switch C comprises a number of conducting segments such as 27, 46 and 28 and insulating segments such as 33, 36, etc., which may be mounted upon a suitable insulating base and are adapted to be rotated by the motor. One method of doing this is operatively to connect the switch 0 with the motor or other part driven thereby by means of sprocket wheels and chain as shown in Fig. 1, the speed of rotation of the switch segments being considerably less than that of the motor so that the switch segments will rotate through an angle of substantially 180 while they motor is driving the bucket from one end of its travel to the other. Stationary contacts such as 29, 31 and 32 are normally in engagement with the contact segments 27 and 28, re-

spectively, while other stationary contacts 1 comprisesa lever 54, operated by the U- shaped lower part of the switch E so as to engage one of the contacts 55 or .56.

The operation of my invention is as follows: Assuming the and mains connectcd to a suitable source of electrical supply, and the loaded bucket B at the bottom of theincline. The lever 49 of switch E is movedover to the left until the contact 51 comes into electrical engagementwith the fixed contact 52. A circuit is thereby closed to the winding of the reversin switch B, said circuit being traced as fo lowsz of-rom the main by wire 65, to and through the winding 2, wire 66, contacts 31, 29 and con-v tact segment 27 of switch C, wire 67, switch contacts 52 and 51, and by the wire 68 to the main. The reversing switch R will now operate to close the motor circuit at the wire 72, contacts 8 and 7 contacts 7, 8 and 9, 12, and 11 respectively, and to separate the contacts 13, 14,. and 15, 16, respectively, The motor circuit is now established andimay be traced from the main to the contacts 12 and 11, Wire 69,

contacts 17 and 18 ofreversing switchR,

of reversing switch R, wire 73, armature contacts 78 and 77 of switch R, wire 79 to and through the starting resistance 10' and seriesfield winding 20, and by wire 81 to the main, The raising of the reversing switch R also closes a circuit to the.

. contacts 11, 12, while the extra field circuit is across the motor armature and may be traced from the brush 74, wire 73, contacts 7 and 8, wire, 72, contacts 18'and 17, wires 69 and 82, through the extra field 40 and resistance 50, wire 83, contacts 25 and contact *disk 24 of relay N, wire 79, contacts 77 and 78, and by wire 76 to the armature brush 75. The motor now starts to rotate with the brake released and all field windings excited, the armature current being held in' check by the starting resistance 10. The closing of the reversing switch R also establishes a circuit to theaccelerating magnet L; this-circuit being across the motor armature and including a small portion of the starting resistance 10. As the motor increases its speed and counter-electro-motive force, the accelerating magnet operates to raise its contacts 20', 21,22 and23, in

successive order so as gradually to short circuit the starting resistance and series field, thereby allowing the motor to run at normal slow speed, with the'shunt and extra fields excited. The next operation isto give the lever of switch E a further movement to the left until the contact 51 en ages the contact 53. A circuit is thereby c osed brush 74, to and through the armature to brush 75, wire 76',-

to the relay N and may be traced from the main contacts 12, 11, and 9, wire 71, solenoid of relay N, wire 84, contact 34, contact segment 28, contact 32, contacts 53 and 51, and by wire 68 to the main. The relay N is thus energized to raise its core and contact plate'24 upwardly, therebyinterrupting the circuit of the extra field at the contact25 and, by thus weakening the motor field excitation allowing the motor to run at normal full speed as a simple shunt machine. As the carriage carrying the loaded bucket approaches the upper curved portion of the incline the controlling switch C which has been rotating in an anti-clockwise direction, moves the contact segment 28 out of electrical engagement with the contact 32, so that the latter now rests upon the insulation' 38 thereby interrupting the circuitof the relay N. The contact disk 24 will now short circuit the contacts 25 and again establish a circuit through the extra field winding 40 and resistance 50 and the increase in field strength which necessarily follows will cause the motor to run at reduced speed. As the motor continues to. hoist the bucket at reduced speed the switch C rotates the contact segment 43 into electrical engagement with the contact 41 thereby establishing a circuit to the winding 57 of the slowdown magnet 60 which circuit is derived from the motor armature and may be traced as follows: from the armature brush 74, by wire 85,'switch lever 54, contact 55, contact segment 43, contact. 41, winding 57, wires 86 and .76 to the armature brush 75.

contacts 59, 61 and 62 in successive order to short-circuit portions of the extra field resistance 50 according to the speed and load on the motor. increase the current flowing in the extra field and the motor will further reduce, its

This operation will tend to.

. The magnet 60 isthen energized to raise its speed. The contact segment 43 next engages the contact 39, establishing a circuit to the slow down magnet 70 which will become energized to raise the contacts 63 and 64 and thus short circuit additional portions of the resistance 50 resulting in a further speed reduction due to increased field strength. By this time the carriage H has traversed the curved portion at the top of the incline and the bucketis nearly over the top of the furnace. As the motor continues to rotate at very slow speed thecontact segment 27 passes out of engagement with the contact 31 and the circuit to the magnet winding of the reversingrswitch R is broken and the core 3 and connected parts drop thereby opening the motor and brake magnet circuits and connecting the stopresistance 19 across the motor brushes.

This circuit may be traced from the brush.

74, through the resistance'l9, wire 72, contacts 15 and 16, contacts 77 and 78, and by stopping by the dynamic action of the rotating armature generating current which is absorbed by the resistance 19, as well as the retardation due to the application of the friction brake J. The operation of the device with a descending bucket is very similar to that already described it being merely necessary to move the lever of switch E in a right hand direction, thereby closing a circuit to the reversing switch It which will establish a circuit to the motor armature in a reverse direction than that pointed out in connection with an upwardly moving bucket. The function of the switch comprising the lever 54: and contacts 55 and 56 is to open the circuit of the slow-down magnets 60 and 70 whenever the switch lever 49 is moved in a right hand direction, and to open the circuit of the slow down magnets 80 and 90 whenever the switch lever is moved in a left hand direction. The automatic slow down for a descending bucket is effected by the switch C as before excepting that in this case the circuit of the relay N will be interrupted at the contact 35, while the slow-down magnets 80 and 90 will be energized at the contacts 48 and 47 and the final stop will occur when the circuit to the reversing switch R is broken at.

the contact 45. While the switch C will automatically take care of the slowing down and stopping of the bucket at the proper point regardless of the direction of travel or speed and load, the operator may at any time stop, slow down or reverse the motor by means of the switch E. I

By the use of separate magnets for effecting the automatic slow down of the bucket at the top and bottom of the incline, I am enabled to regulate or adjust the retardation of the motor and load at the top and bottom independently of each other. The manner of effecting this result is as followsz-The.

contacts of the magnets 80 and 90 are adjusted when the bucket is being lowered so that the air gap between these contacts and the corresponding contacts carried upon the magnet frame is such that not only will they operate in the proper sequence so as to short circuit successive steps of resistance but also that each one will respond to a predetermined amount of magnet strength, which, by virtueof the connections of these magnets, namely, across the armature brushes, will be proportional to the counter-electromotive-force of the motor, or in other words, the speed. The regulation ofthe slow down at the top of the incline is done in a similar manner by adjusting the contacts 59, 61, etc. of the magnets 60 and 70. It will be not-iced that the connections of the contacts 63 and 64 alon the resistance 50 are somewhat different rom those of the contacts 63' and 641' The contact 64, which operates only when the bucket is traveling upwardly, is connected so as to short-circuit the entire resistance 50, so thata very slow speed before stopping is produced, which is desirable at the upper limit since the bucket is now heavily loaded and may contain, and frequently does, a load of everal tons. It is readily seen that such a load must be handled very carefully so as to prevent .the bucket from setting up a swinging motion due to a too rapid change in speed.

While the various contacts of the automatic switch C have been referred to as fixed it is to be understood that they may be and preferably are adjustable about a common center. In this manner the slow down for both up and down travel may come into operation at any desirable position of the bucket while the operation of the magnets 60, 70, 80 and 90 will depend upon the load and speed of the motor. The number of magnets and contacts for controlling the slow down resistance 50 maybe varied as desired, a greater refinement in operation being effected by usin a large number of contacts and correspon ing steps in resistance.

.VVhile I-have described my invention as particularly adapted to a blast furnace hoist, it is well ada ted to be used in connection with other 'nds of inclined hoists in which it is desired 'to effect, an automatic slow down for both directionsof travel and at the same time permit an adjustment best adapted for the slow-down in. one direction without interfering with the slow down for the opposite direction.

Various changes could readily be made in the apparatus herein shown and described by one skilled in the art without departing independently of each other.

2. In a furnace hoistlng apparatus, the

combination with a load carrying device, of

automatic means for reducing the speed of said device-atpredetermined points in its travel, and means for controlling said speed reductions independently of see other.

' 3. In a furnace hoisting apparatus, the

combination with a motor andv load carrying device, of means controlled by said motor for reducing the speed of sand device at predetermined points in its travel, and means for controlling said speed reductions-independently of" each other.

at. In afurnace hoisting apparatus",- the combination with a motor and load carrying device, of means'independent of each other for automatically effecting a. reduction in the speed of the motor and means for varymg the actlon of saidspecd reducing means. 5. In a furnace hoisting apparatus,- the combinationwittia motor, of a load carry-. I mg device operatively connected therewith, independent means for effecting a reduction in the speed of the motoryandnnean's operated by themotor for controlling-theoperation of said speed reducing means."

6. In a furnace hoisting apparatus;- the combination with a loadcar1ying=device and a' motor o u-rativcly connected thereto; of means for eontrollm the speedof themotbr in one direction, ad itlonal means-for controlling the speed iii-the opposite direction;

and means for controlling the ac'tionof both of said controlling-means.

7. In a furnace hoisting apparatus, the combination with a load carrying device and a motor operatively connected thereto,- of means for controllingzthe speed'of the motor in one direction, additional means for controlling the speed in the opposite direction, and means controlled b. the motor for effecting the operation 0 both of said controlling means.

8. In a furnace hoisting apparatus, the combination with a load carrying device and a motor operatively connected therewith, of means separate from each other for effecting a reduction in speed of the motor at predetermined points in the travel thereof, and means controlled and operated by the motor for effecting an intermittent operation of each of the speed reducing means.

9. In a furnace hoisting apparatus, the combination with an electric motor, of a resistance in a circuit of the motor for controlling the speed thereof, independent means for varying said resistance. and a circuit controlling mechanism for effecting the operation of said resistance varying means.

1.0. In a furnace hoisting apparatus, the combination with an electric motor, of a resistance in a circuit of the motor for controlling the speed thereof, independent means controlled by the motor for varying said resistance, and a circuit controlling mechanism for said resistance varying means.

ll. In a furnace hoisting apparatus, the combination with an electric motor, of a. resistance in a circuit of the motor for controlling the speed thereof, independent means controlled by the motor for varying said resistance in proportion to the speed of the motor, and a circuit controlling mechanism for said resistance varying means.

said resistance, and a circuit controlling mechanism operated by the motor for effectingthe operation of said' resistance varying means.

13; In a furnace hoisting apparatus, the ,combination with an'electric motor, of are- ;sistance in afield windin circuit of themoitor, electro-iesponsi\e devices fol control- .ling said resistance in, proportion to the speed of the motor, and means for energiz- -ingone'or the other of' said-electro-responsive" devices accordingto'the direction of rotation of said=motor.

: 14: In a furnace hoisting,- apparatus, the :combination'witlran electric motor,-of arrefsistance ina field'winding'=- circuit ofthe motor, electro-responsive devicesfor controllingsaid resistance in proportion to the a speed of the 1notor,.and means controlled by the motor for etfecting' the operation of one or the other of said electro responsive devices according-to the direction ofrotation oftsa-id'ntotor.

, 15. In a furnace hoistingapparatus, the combination with an electric motor, of two electro-magnets arranged to be connected lacross the motor armature, a resistance controlled by said electro-magnets for varying the speed of the mot0r,,anda device controlled by the motor forlclosing the circuit of one or the other of said electro-magnets according to the direction of rotation of the motor.

16. In a furnace hoisting apparatus, the combination With an electric motor, of two electro-magnets arranged to be connected across the motor armature, a resistance in series with a field winding of the motor and controlled by said electro-magnets for effecting a speed reduction of the motor, and a device controlled by the motor for closing the circuit of one or the other of said electro-magnets according to the direction of rotation of the motor.

17. In'a furnace hoisting apparatus, the combination with an electric motor, of means controlled by the motor for effecting a speed reduction in proportion to the load, a circuit controlling device operated by the motor for effecting the operation of said speed controlling means, and means for yarying the action of said speed controlling means independently of each other.

18. In a system of motor control for furnace hoist; skips, the combination of an electric motor, a load carrying device operated thereby. means to effect an automatic reduction of speed as the load carrying device approaches one limit of travel, and means to effect a different rate of speed reduction as the load carrying device approaches the opposite limit of travel.

19. In a system of control for furnace hoist skips, the combination of an electric motor, a load device, means connecting the motor and load device for lifting and lowering the latter, a field circuit for the motor comprising sectional resistance, means for automatically establishing said circuit and cutting out a portion of the resistance as the load device approaches one limit of travel, and means to establish said circuit and cut out a difiercnt amount of said resistance as the load device nears the opposite limit of travel.

20. In an electric furnace hoist, the combination of an electric motor, a dynamic circuit therefor comprising a sectional resistance, an automatic controller geared to run with the motor, an electromagnet having its circuit extended through the controller and controlling the said resistance When the motor is operating in one direction, and a separate electromagnet having its circuit extended through the controller and cont-rolling the resistance when the motor is operating in the opposite direction.

21. In an electric furnace hoist, the'combination of an electric motor, resistance in a circuit of the motor, an elect-romagnet controlling said resistance when the motor is operating in one direction, and a separate electromagnet controlling said resistance when the motor ,is operating in the reverse direction.

22. In an electric furnace hoist, the combination of an electric motor, a field circuit comprising sectional resistance, an automatic controller, elect romagnets controlling said resistance and having their circuits extended through the controller and arranged to be closed in succession during the opera tion of the motor in one direction, and additional electromagncts controlling said rosistauce andvhaving their circuits extended through the controller and arranged to be closed in succession during the operation of the motor 111 the reverse direction.

In testimony whereof, I have signed my name to this specification in the presence of r two subscribing Witnesses.

' FRANK I. SMITH.

Witnesses GEO. SWANSTON, SAM SCHAGREN.

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