US1388906A - Electric-motor-control system - Google Patents

Description

. WACKERLY ELECTRIC MOTOR CONTROL SYSTEM.

APPLICATION FlLED JULY21,1920.

Patented'Aug. 30,1921.

2 SHEETSSHEET 1- UNITED srA-rss' PATENT OFFICE.

BARRY A. WACKERLY, 0F ALLIANCE, OHIO, ASSIGNOR TO THE Molten: ENGINEER- ING- COMPANY, OF ALLIANCE, OHIO.

ELECTRIC-MOTOR-OONTROL SYSTEM.

Specification of Letters Patent. Patented Aug, 30, 1921 Application filed July 21, 1920. Serial No. 397,820.

To all whom it may concern Be it known that I, HARRY A. WACKERLY, a citizen of the United States, and a resident of Alliance, in the county of Stark and State of Ohio, have invented certain new and useful Improvements in Electric-Motor-Control Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as willenable others skilled in the art to which. it appertains to make and use the same.

[This invention relates to improvements in electric motor control systems, and more particularly to means for automatically controlling the limit of travel of machinery, such as hoisting means operated by an electric motor, one object of the invention being to provide ellioient means for preventing overtravel of the mechanism, such as a hoist, by automatically stopping the driving motor at a predetermined point in the travel of the hoist or other member of machinery driven by said motor; to so construct and arrange the switch devices and circuits which they control that said switches shall be re" set automatically when the motor circuit is reversed, and to so construct and arrange said means that the action of the switches shall be quick, positive and eflicient and caused to operate in proper succession to effect the desired results. u

A further obyect is to so construct limit switch mechanism in a system of electric motor control, that said mechanism shall be operated mechanically by a part driven by the motor to efiect the stopping of the motor and so that it will be operated electrically in effecting resetting of said mechanism.

A further object is to rovide electrically actuated means cooperab e with limit switch mechanism which will operate automatically to insure quick shifting and intimate engage ment of contacts of the switch devices when the same are operated to eil'ect the stopping of the driving motor, and which will also op crate automatically to shift the switch de vices in the resetting of the latter.

With these and other objects in view, the invention consists in certainnovel features of construction and combinations of parts as hereinafter set forth and pointed out in the claims.

In the accompan "ing drawings; Fi re 1 is a diagrammatica view illustrating t e ar rangements of circuits and devices when my improvements are applied to motor driven hoist mechanism; Figs. 2, 3, 4, 5, 6 and 7 are diagrammatical views illustrating the operation of the mechanism; Fig. 8 is an enlarged view in elevation showing the construction and arrangement of the limit switches; Fig. 9 is a view taken at right angles to Fig. 8, the casing being shown in section, and Fig. 10 is a detail view showing the cross bar with which the weight is connected.

In Fig. 1 of drawing, I have illustrated a controller at 1 provided with suitable contacts whereby shifting of the circuits through the resistance and the motor windings may be effected-said controller being provided with suitable step resistance elements indicated at 2 and 3 and with a permanent resistance 4: for the armature circuit. Conductors are indicated at 5, 6, 7,8 and 9, and the conductor from the ositive'side of the source of electrical supp y is indicated at 10 as connected with the conductor 5. The con doctor 11 from the negative side of the source of electrical suppl is connected with the controller. The con uctors 5 and 9 are connected, respectively, with the respecive terminals ofthe solenoid of a brake indicated at 12, and this circuit (indicated at 13) also includes, in series, the coil of a solehold 14-, which is series wound with the noid l4 and the brake solenoid) that poles of like sign of the two solenoids 14 and 15 will, normally, be presented to each other and result in a re ellin tendency to cause movement of the so enoi 14 for a purpose to to be hereinafter ex lained, One terminal of the solenoid 15 18 connected by a con-- ductor 16 with the conductor 7 and the other terminal of said; solenoid 15 is connected by a connector 17 with a contact block 18 of a serv ice limit switch A, This limit switch includes also a contact block 19 with which the conj tact block 18 codperates and also co6perat-= ing contact blocks wand 21., The terminals of a resistance 22 are connected respectively with the contact blocks 18 and 19 and the latter is connected by a conductor 23 with.

the contact block 2-0.. The contact block 21 is connect y a conductor 24 with the contact till till

block 25 of an emergency limit switch and the letter also includes a contact blocl: 26 cooperable with the contact block 25, and contact blocks 27 and 28 coiiperable with each other.

The contact bloclr 19 oil limit switch A is connected by a conductor 29 with one side of the armature 30 oi a driving motor and the other side of said armature is connected by a conductor 31 with the contact bloclr- 26 oi the limit switch B and said contact block is connected by a conductor 3% with the contact block 27. The contact blocl-r 25 ct limit switch 18 is connected by a conductor 33 with a conductor 34l,-one end of the latter being connected with one terminal of the field coil 35 of the motor and the other end of said conductor 3 is connected with the conductor 5. The other terminal of the field coil is connected by a conductor 36 with the conductor 8 and said conductor 36 is connected by a conductor 37 with a resistance 38, the latter being connected, through a conductor 39 with the contact bloclr 28 oi jzhe limit switch The conductors d and 8 (with which the conductors 34: and 36 leading from the field terminals are connected) are connected, by conductors 0 and 41 with the controller andthe conductors? and 9 are connectedby conductors l2 and as with the controller, whereby the shifting oi the circuit c0nnections through the motor and the coil oi solenoid 15 may be effected.

The limit switches A and B and the solenoids it and 15 may be located in a frame or casing 4 as shown in Figs. 8 and 9 and this frame or casing may be nrovided with suitable feet or supports 45. Standards do are located in the lower portion of the frame and provide bearings icr'the bell-cranks A and 5B of the limit switches A and B, the contacts 19-20 and 2 8-27 of these switches being preferably made of carbon and clamped in holders 47-48 and 49-50 having threaded or other adjustable connection with and forming, in efi'ect, portions of the bell-cranks of the switches, and said contacts and their holders are electrically separated from the remaining portions on? the bell-cranks and their supports, by means oi insulators 51. The stationary contacts 18, 21, 25 and 28 oi the limit switches may be made of copper and are supported by the frame 44 and electricall separated from the latter by means of insu ators 52. The bellcranks of the limit switches are provided with arms 53 connected by a cross bar 54,

the ends of which are loosely mounted on the arms 53 of the respective switches and the intermediate portion of said cross bar is provided with a series of perforations 55,-in an of which a cord 56 may be connected. his cord carries a suspended weight 57 to be engagedand by a part,

58 on a member ct hoisting; mechanism, as. indicated at 59.

The clamps or holders i8 and 50 which carry the contacts 20 and 2? of the respective limit switches, are provided with lugs 60, 61, and these lugs are connected by a cross bar 62 pivotally connected therewith. The cross bar 62 is made liher and com prises two parallel members, between which a coupling member 63 is pivotally connected in proximity to the connection at said cross bar with the lug 60 on the clamp or holder d8 on the bell-crank of switch A. A link 64 is pivotally connected with the movablesolenoid 1d and, through the medium oi the coupling 68 with the cross bar 62, the tired solenoid 15 is secured to the casing over the movable solenoid is. it will be observed that by means of the construction and arrangement of limit switches, as above described, said switches will normally be maintained in the positions shown in Figs. 1, 8 and 9 by the action of the weight 57, and that when said weight is raised by the "upward travel of the hoisting means, the switches will be shifted As the solenoids 1 15 are so wound that one will repel other, the movable solenoid 1% when free descend, will exert sufficient force on the switches to shift them quickly and cause the movable contacts to firmly engage the tired contacts. @wing to the connections above described between the two limit switches A and the connection of the cross bar 62 with the movable solenoid, the switch A will close the circuit at contacts 202l prior to the closin of a circuit at; 27-28 by movement or" t e bell-crank of switch B. The reason for such successive o eration of the two limit switches will be c' early understood from the following description of the operation or" my improvements and the circuits and devices with same circuit. When t e wei ht 57 is raised by the upward travel of the oisting means, 7

the-belhcrank of the service limit switch A will firstbe shifted to separate the contacts 18-19 and close the contacts 20-21.; This shifting of the switch A will operate to short-,clrcuit the armature of the motor, (as shown in, Fig. 3) causing the same to stop quickly by reason of the dynamic b efi'ect produced, as will be readily under-' stood. The same shifting of the switch A will, in addition to short-circuiting the arma e, the e istance 22 to choke an also shown in this excessive current which would otherwise flow through the field and solenoid windings, as also indicated in Fig. 3. Immediately after the switch A has been shifted, producing the results just described, the emergency switch B will be shifted as previous y explained, thus separating the con.- tacts -26 and closing the contacts 2728.

The armature, field, and resistance 38 are When the current in the armature circuit is thus reversed, the direction of current in the coil of the fixed solenoid 14 will also be reversed, with the' result of changing the polarity of the latter so that poles of different signs of the respective solenoids 14 and 15 Wlll be juxta-disposed and the movable solenoid caused to rise and tend to shift the limit switches successively,the service limit switch A being first shifted, so that the circuits shall be as illustrated in-Fig. 6, and immediately afterward the emergency limit switch will be shfited so that the circuit con-. nectionsshall be as shown in Fig. 7,the

latter figure of the drawing showing the circuits in reset.

From the above, it will be seen that the resetting of the limit switches is effected in succession electrically, and that the same devices are also utilized in insuring the positive and effective enga ement of thecontacts of the switches when t e latter are operated to efiect the sto ping ofthe motor and also when they are s ifted to normal osition.

It will also be seen that at no p ace in the wering position with both switches cycle of operation of the cut-out is the main line circu1t opened.

. ters-Patent, is

Having fully described my invention what I claim as new and desire to secure by Let- 1. In a motor control system, the combination with an electric motor, circuits there-.

for, and controlling means for said circuits, of a limit'switch, motor operated means for netic shifting said switch to short circuit the motor armature, and electrically controlled means for resetting said switch when the controlling means are operated to reverse the current in the armature circuit.

2. In a motor'control system, the combination with an electric motor, circuits therefor, and controlling means for said circuits, of two limit switches, motor operated means for shifting said switches, andmeans causing said switches to shift successively, first to short-circuit the motor armature and then to include both armature and field of the circuit, electrically controlledxmeans con- I nected with said switches and operative to press movable contacts thereof against fixed contacts, said electricall controlled means also operative. to shift t e switches to nor-- mal position when the current in the armature circuit is reversed by operation of said controlling means.

4. In a motor control system, the combination with an electric motor, circuits therefor, and controlling means for said circuits, of a limit switch, a fixed and a movable electro-magnetic device included in the motor circuit and normally adapted to have repellent relation to each other, connections between the movable electro-ma etic device and said switch, means operate by the motor for shifting said switch to short-circuit the m torarmature, one of said electro-magdevices adapted to be included in the armature circuit, whereby when the current in said circuit is reversed by operation of the c'ontrollin means, the polarity of said elecvices caused to...reset the limit switch.

In testimony whereof, I have signed ,this specification in the presence of two subscribing witnesses.

fl HARRY A. WACKERLY.

Witnesses: a

N. C. Fn'r'mns, M. C. Wrsm.

tromagnetc device will be changed and cooperation of the two electro-magnetic de--

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