US1200264A - Electrically-operated hoist. - Google Patents

Description

E. L. STONE.

ELECTHICALLY OPERATED HOIST; APPLICATION mm SEPT. 14, 1914.

1,200,26L Patented Oct. 3, 1916.

Witnesses: Inventor:

2 2- aw E H i s Attorn e13 UNITED STATES PATENT OFFICE.

FRED L. STONE, OF

Specification of Letters Patent.

scHENEc'rAnv, NEW vomz fnssroivoa TO GENERAL ELECTRIC" COMPANY, AGORPORATION or NEW YORK. a

Patented Oct. 3, 1916.

Application f led September 14, 1914. Serial No. 861,504.

To all whom it may concern Be it known that I, FRED L. STONE, a subject of the King of Great Britain, residing;

at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Electrically-Operated Hoists, of'which the following is a specification.

My invention relates to electrically operated hoists and has for its object the provision of means whereby the overwinding of the hoist due to carelessness of the oper- V ator or other cause is prevented.

In the operation of hoisting machines, such, for instance, as m1n1ng holsts, the

' cages travel at a relatively high speed, and

it is therefore necessary that the motor be slowed down some time before the stopping point is reached in order to eflect a safe landing without over travel. For instance,

,if the operator should neglect to slow down his motor when the cage nears the limit of its upward travel it may be impossible to stop it at the landing and it will therefore overtravel and may cause serious damage.

One of the objects of my invention 1s to provide means whereby in case the operator fails to slow down at the proper time or at the proper point in the operation of the hoist the motor circuit will be automatically opened.

In carrying out my invention I provide two circuit controlling devices for control-' ling the motor, one controlled by the speed oi the motor and the other controlled by the position of the hoist. The arrangement -is such that the motor circuit can only be closed when the circuit controlling devices are in corresponding positions, that is, when the hoist is in a certain position, the motor must be at a certain speed, otherwise the motor circuit will be opened. In this way, when the cage reaches. certain positions at which the operator should slow down to a certain speed, if he does not slow down to this speed the motor circuit will be opened, and the hoist will be automatically stopped.

Other objects and features of my invention will appear in the course of the following specification in which I have d1sclosed my invention. embodied in concrete form for purposes of illustration.

The accompanying drawing illustrates my invention applied to one form of electrically driven hoist.

its application to this particul'ar form of hoist. The two cages are indicated at C, C attached to two cables 0, 0 These cables wind and unwind from the drums D and D which are mounted upon the shaft S driven by an electricmotor-M, which. is here illustrated as a three phase induction motor. Current is supplied to the motor by the three legs 1, 2, 3 of a three phase supply. line, controlled by a switch 4, hererepresented as one which can be opened and closed by an electromagnet 5 in a controlcircuit 6 supplied with current from mains 7. The rotor of the motor is equipped'with collector rings 8- connected to a resistor through switches in a receptacle 9 connected to a controller 10, so that the operator withdrawn from the disk by a coil '13 in the control circuit 6 when control circuit is closed. A speed responsive device 14, here represented as a fiyball governor, is geared to the shaft, and actuates the movable contact of a switch, preferably by means of a lever 15 fulcrumed at 16, and having one arm pivotally engaged with the movable sleeve 17 of the speed governor. The other end of thelever is connected to two sliding contacts 18, 19, each cooperating with its' also with a single contact 22,23, parallel with said segments. The movable contacts 18, 19 are mechanically, but notelectri-. cally, connected, preferably by the rigid rod 24 on which they are mounted, butfrom which they are insulated. The contacts 22,

23, form part of the control circuit 6.

The shaft S carries two pinions which mesh with spur gears 25, 26 secured to two long screws 27, 28, the former right hand and the latter left hand. Engaged with each screw is a fleeting nut 29, 30, restrained from rotation by guide rods 31, along which they can slide. Parallel with the screws are the rods 32, 33, each attached to an insulated contact 34, 35 which cooperates with 'own set of insulated segments 20, 21 and Q38 and are long' enoughtocover mentsin their respective banks; 'fThe; rods; in'line with" the nuts 29, 30 re -g 32, 33' are 'abank of insulated segments' :The

I twocontacts' 34, 3.5 are-electrically connectond tm 3 all th s e-'3 ed, for example, byathe flexible spective1y-,g so that they willbef struc'l; by I said nuts when the latter travelto the .left "inthe drawing. Azweight 39 attached to -a faThe" operation cord connected to eachco'ntact 34:, 35 and running over a-pulley 4:1", brings the con-' tacts back-"to the right when the nuts-are backedaway l Thejsegments in; all four banks 20, 21,

36, 37,; are; equal in-fnumber, and those in banks'j20, 21, fnumbering from left to right,

are connected electrically by groups of .con-

ductors 42, 43' respectively, with corre vspending segments. in banks 36, 37, numberin'g from right to left; the two groups of 'conducors' and their-- terminal segments forming portions of the control circuit, con- 'nectedzun SGIIBS;

partsto stand as in-the drawing, and that the engineer starts tohoi'st the cage C. The

motor acquires full speed veryquickly and' "maintains a uniform speed until near the end of the run, when theoperator-is sup-- posed to cut the resistance into the rotorxcir-.- cuit and slow .it down to bring the cage safely and' accurately to the landing, J .wher e .it isstopped by opening and applying the brake ;As the motor acfull" speed, the governorballs'willfl and the the same rate that the contacts'18, 19 are drawn-over the segments 20,21, thus keep 'ing the controll circuit Gclof'sed. If the'engineer cuts in-his motor too rapidly, ithe'sipeed controlled contacts 18, i=9 will outrun the I cage controlled contact 34: and the motor cir cnit'willbe opened at the switch t. Assumm h howeyenn that this has not occurred, t e- Just here the nut 80, which has been travelthe bar: contact '35. speed governor, slowing-down with the mos-f tor, begins to push the contacts l8 ,19 to the -=ing along its screw as the cage came up,

strikes the rod. 33' and begins to push back Simultaneously, the

right 'over'the segments 20, 2l atthe same speed as the contact 35, until, when'the cage C comes ,to the top, the-speed controlled is as followsi Assume the the ..motor circuit cage. will hehoisted rapidly until, near fltheL-e'nd .ofitsrun, the engineer begins to f cut in resistance to slow down the motor.

but permits the speed. governor tohold the contacts- 18, 19 at the left until afterthe nut 30 has begun slidingfthe contact 35 to the left overthe segments 37,: the control circuit.

will be broken at oneof 'thesesegmentszand the motor will be stopped-L Soytoo, if 1 the f engineer does not stop the: cage when .the'--. contact 35"is on the last .of the live. 'segments .37, the

stop the cage.

The drawing is wholly lillustrative does not attempt to show the parts in their proper proportions-or relations. .The screws v, a

order to shift the contacts 34, 35 over the eflif tire bank'ofsegme'nts 36, 37 during the c0m-- 27, 28 will have to be ofa steep-pitch-in contact willfrun 'oif .on the vead segment,break the control}circhit,'and

paratively short timein which the motor is accelerating andslowing down. In other words, the fleeting nuts will be travelin said screws comi into service onl at the I fidly forthe greaterpart of the length 0 outer ends of he ;screwsl*flf-necessary, the I movement of the could be multiplied by suitable means to-insurm a greater vand quicker travel: of. thecontacts 34,, 35, as will be readilyapparent to thelskilled engineer. It is also' evident-that if the s ystem is ap pliedtoa b61517 having but one cage, the

-. switches '2 ljand 35 ."andthe group of circuits 1 423 could be dispensed with; the bar 23 being:

connected directly; to. the contact 34;

\iIn-accordan'ce ?with the provisionsofthe patentjstatutes, I have described the principle of operation of my invention, together with the apparatus which-I now consider to represent the best embodimenttthere'of; but I desire toha tie it understood that the apparatus shown I is fonly illustrative, and that the invention can be carried out by other means. j

WhatI-claim as new and desire to secure by Letters Patent of theUnited- States, is

1. The combination/with the motor of an electric hoist, of; means for gradually varying'the speed ofsaidmotor between certainpoints in the travel of the hoist,'comprising a controller, a speed responsive device actuatingthe same to various positions, a second controller actuated by the hoist, and connections between the controllers for effecting the control when the controllers arenot' in corresponding positions,

2. The combination with the motor of an electric hoist,'of means for automatically controlling [said 3 motor comprising two cir- 'cuit controlling devicesconnfected in series in the motor control circuit and adapted during acceleration and deceleration of the hoistto assume corresponding positions, one

controlled by the speed of the motor'and-the' switch will be in the position illustrated, and other controlledbythe position of the cage g, the contacts 3%, 35 MB occupy positions the or number of revolutions ofmotor.

3. The combination with th'e "motor of an reverse of those shown If the engineer does not slow down the motor soon enough,

' electric hoist, of means for autonr1';n'sically cuit controlling devices each having a p1u-.

rality of controlling positions, one of said devices being controlled by the speed of the motor and the other controlled bye-the position of the cage or number of revolutions of motor, and connections whereby the two devices must be in corresponding positions in order that the motor circuit will be closed.

4. The combination with the motor of an electric hoist, of ,a control circuit therefor containing a group of parallel conductors, a switch at one end of said group controlled by a speed responsive device, and a switch at the other end of said group controlled by] nected switches cooperating with the segthe movement of the cage. I

The combination with the motor of an electric hoist having two oppositely moving cages, of a control circuit therefor containing two groups of parallel conductors said groups being connected in series, switches at the remote ends of said groups controlled simultaneously by a speed responsive device, and electrically connected switches at the adacent ends of said groups controlled re- 'spectivel by the cage driving mechanisms.

6. Means for preventing the overwinding of an electric hoist, con'iprlsmg an electric control circuit for the motor, a plurality of circuits each terminating at each end in the cm'responding segment'ot' -a bank of segmeuts, a speed controlled switch connected to the control circuit and cooperating with one bank of segments, and a switch cooperating with the other bank and actuated by the hoist during the latter part of its travel.

7. Means for preventing the overwinding v of an electric hoist driving two winding drums, comprising an ele ric control circuit for the, motor .wvhich includes-.twc' groups ot parallel conductors each termini-ting at each cud in one of a bank of segments, two switches cooperating with the segments'at one end of said groups, a speed responsive device operatively connected to both switches, electrically connected switches cooperating with thesegments at the other end of said groups, and mechanism geared to each drum for operating itsrespective switch.

8. Means for preventing the overwinding of an electric hoist driving two cages, comprising an electric control circuit for the motor which includes two groups of parallel conductors each terminating at each end in one. of a bank of segments, two switches cooperating with the segments atoneend of 'said groups, a speed responsive device operatively connected to both switches, conments' at the other end of said groups, and

mechanism geared to each cage for operat-' prising an electric control circuit for the motor including two. groups of parallel conductors each terminating at each end in one of a bank of segments, two switches c061 erating with the segments at one end of said groups, a speed responsive device operatively connected to both switches, connected switches cooperating with the segments. at the other end of said groups, and mechanism geared to each cage for operating its res ective switch during the upper portion 0 its travel only, both in hoisting and lowering,

and simultaneouslywith the movement of the speed controlled switches,

In witness whereof, I have hereunto-set my hand this 12th day of September, 1914.

BENJAMIN B. HULL, BENJ. H. WVEISBROD.

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