US1955227A - Rheostat switch - Google Patents

Description

April 17, 1934. w. o. DENNIS RHEQSTAT SWITCH Filed Oct. 27. 1930 2 Sheets-Sheet, 1

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April 1934- w. o. DENNIS 1,955,227

mmosm'r swrrcn Filed Oct. 27, 1930 I 2 Sheets-Sheet, 2

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A TTORNEY Patented Apr. 17, 1934 PATENT OFFICE UNITED STATES ,22 mosm'r swrrcn William 0. Dennis, km City, it.

Application mm 21, 1930, Serial No. 491,021

Claims. (01. zoo-oz) This invention relates to electric switches, and more particularly to an automatic rheostat switch adapted for remote operation in controlling electric circuits, vfor example, a circuit controlling a 5 slip ring induction type motor; the principal object of the invention being to provide a positively operated switch of simplified and compact construction for controlling of comparatively heavy electric currents.

Another object of the invention is to provide a switch wherein the operating mechanism may be readily removed from its panel for repairs or replacement without disturbing electrical connections or other wiring.

In accomplishing these and other objects of the invention, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a front elevational view of a rheostat switch constructed in accordance with my invention.

Fig.2isaverticalsectionalviewthroughflie switch on the line 2-2, Pig. 1.

Fig.3isa viewillustratingcircuits for remotely controlling the switch, as connected in circuit with a slip ring induction motor.

Referringmoreindetailtothedrawina:

The switch illustrated is particularly for controlling operation of a three phase slipringinductiontypemotorandincludesafixed panel 1 preferably formedof insulating material, sothatthecontactsaudotherwiringforcontrollingamotorcircuitmaybedirectlymmmted thereon, which, in the present instance, includes threeseriesofspacedcontactpla i 2,3,and4,andconnectedcontactstrips5,6and 'Lwiththerespectiveseriesofcontacts for connectingelements 10, 11and12 into the motor circuit as later described.

The contact platesofoneseriesaremounted ontheponelintwiththecontactplates ofeachoftheotherseriesbyscrewslilextendmg throughtheplatesandintothepanel. Thecontactstripsarecoextenslvewiththeseriesofcontactplatesandaremoimtedonthepanelby screwsiiextendingthroughtheendsoftbestflps asshowninl'ig. 1. I

Supportedadjaeenttheupperandloweredges oi-the panel and extending longitudinally of the seriesofcontactsarerailsortracksl5andl6 preferablycomprisingrodshavhiglaterallybent ends1'IprovidedwithdImlders18thefaceofthepanelandthreadedterminalswhichextendthroughthepanelandaresecuredther'etobynutslflthradedontheextensionstodraw theshoulders tlghtagainsttheface of thepanel. Thetrackslfiandlfiarethusspacedfromthe faceofthepanelbythelateralextensionsl'lto te switch m now described. 'Mountedonthetracks15and16audadapted 00 tomove therealong'overthe contactsisacarrlage 20 preferably comprising -a rectangular plate 21 of insulating materialextendingfrom thetopto thebotwmofthepaneLasbestillustratedin Fig. 1. Rotatably mounted on the lower ends of 66 theplatearegroovedrollersnadaptedtobear ontheuppersideofthetrack16,andflxedto therearoftheplateatitsupperendarerearwardly extending brackets 23 carrying grooved rollerszlforengagingtherearfaceofthetrack 15, as illustrated in Fig. 2. The carriage, including the plate 21,isthus mounted forrolling movementonthetracksandmaybereadilydetachedtherefrombyraisingthelowerendofthe platetoremovetherollersziifroment II with thelowertrack 16, after whichtherollers 24maybeunhookedfromtheuppertrack15.

on the rear side oi ductlongearingddoforactuatingagear 41iixed mashaft42projectingfmmtherear imoithcplatezLandwhichmesheswitha no plate 21 by rack bar 43 fixed to the front side of the switch panel adjacent the lower track 16. Thus it is apparent that when the motor 34 is energized, the pinion 39 will actuate the transmission gearing 40 to rotate the gear 41 and cause it to roll along the rack bar to move the carriage on the tracks 15 and 16 and connect the contact plates in series with their respective contact strips, thereby cutting out resistance in the motor circuit or adding resistance, depending on the direction of travel of the carriage.

In order to stop the motor and prevent coasting of the armature when the motor circuit is broken as later described, I provide the armature shaft 37 with a cone-shaped disk 44 which is normally urged into braking engagement with a complementary-shaped brake flange 45 fixed to the a coil spring 46 sleeved on the armature shaft and having one end bearing against the pinion 39 and its opposite end against the motor carriage plate 21, so that when the brake disk is in engagement with the fixed member 45 the spring 46 draws the armature of the motor from the center of its field and when the circuit to the motor is again closed, energization of the motor field will cause shifting of the armature to release braking action of the disk 44.

Supported by the carriage plate 21 above the motor is a reversing switch indicated in Figs. 1 and 2 by the housing designated 47 in Figs. 1 and 2, whereby the current through the armature may be reversed to change direction of rotation of the motor and consequently direction of travel of the carriage. The switch 47 preferably includes a bell crank lever 48 (Fig. 3) pivotally mounted by apin 49 on the front face or the plate 21, and having an upwardly projecting arm 50 provided with mercury tube switch receiving seats 51 and 52. The other arm of the bell crank lever 53 is connected by a link 54 with an arm 55 Ma second bell crank lever 56 pivotally mounted by a pin 57 projecting from the plate at a point below the pin 49 which mounts the bell crank lever 48. I The other arm 58 of the second bell crank lever 56 depends downwardly and can'ies a weighted armature 59 operable between a pair of electromagnets 60 and'61. The magnets 60 and 61' include U-shaped pole pieces 62 and 63 having magnet coils 64 and 65 so that when the magnet 54 is energized as later described, the armature 58 will be drawn toward themagnet 60 to swing the bell cranks in one direction, and when the other magnet is energized the armature will be actuated to move the bell cranks in the opposite direction for closing and opening circuits to the carriage actuating motor 34 as now described.

Supported in the seats 51 and 52 are mercury tube switches 66 and 67, each having a central pocket 68- ior retaining a quantity of mercury 69 when the mercury tube switches are in horizontal position, i. e., when both'magnets are deenergized and the armature 59 depends by gravity between the magnets 60 and 6l,'at which point all circuits to the actuating motor are open, the mercury being adapted to flow from the pockets to close the circuits when either of the coils is energized. The mercury tube switch 66 is provided in its opposite ends with pairs of terminals 70-71 and 72-73, and the mercury tube switch 67 is also provided with similar terminals 74-75 and 76-77, which terminals 70-71 and 74-75 are adapted to be connected by the mercury to close circuits to operate the motor in one direction, and the terminals 72-73 and 76-77 are adapted to reverse the current to operate the motor in the opposite direction as now described.

Fixed to the switch panel and extending parallel with the contacts previously described are laterally spaced contact strips 78, 79, 80 and 81 for conveying current to the actuating motor 34 and the magnet coils through brushes 82, 83, 84 and 85, respectively, which are carried on the bar 27 similarly to the brushes previously described.

86, 87 and 88 designate the line wires of a three phase electric circuit and connected with the line 87 is a wire 89 for supplying current to the contact strip 81 and through the strip to the brush connected by a wire 90 with the terminals 75 and 76 of the mercury tube switch 67, the wire 90 being connected in series with one of the windings 91 of the carriage actuating motor 34.

Connected with the supply line 86 is a conductor 92 for adapting completion of the circuit through the contact strip 78, brush 82 and a conductor 93 connecting the terminals 71 and 72 of the other mercury tube switch 66.

The terminal 70 of the mercury tube switch 66 and the terminal 77 of the mercury tube switch 67 are connected together by a conductor 94 which is connected to one of the brushes of the motor 34 by a conductor 95. The remaining terminal 73 of the mercury tube switch 66'is connected by a conductor 96 with the remaining terminal 74 of the mercury tube switch 67 which in turn is connected to the other brush of the motor 34 by a conductor 97.

Thus when the mercury tube switches are tipped to the right (Fig. 3), the mercury closes circuit through the terminals 72 and 73 01 the mercury tube switch 66 and through the to nals 76 and 77 of the mercury tubeswitch 67 thereby completing circuit from the line wire 87 through conductor 89, contact strip 81, brush 85, conductor 90, field winding 91, terminals 76 and 77, conductor 95, armature of themotor 34, conductor 97, terminals 72 and 73 of the mercury tube switch 66, line 93, the other field winding 98 of the motor 34, brush 82, contact strip 78, line wire 92 to the feed line 86, energizing the motor to move the carriage over the series of contacts 2, 3 and 4 to cut out resistance elements 10, 11 and 12, V

The motor 34 will continue to move the carriage across the contacts until all of the resistances are out of circuit, at which point the motor may be reversed by tipping the'mercury tube switches in the opposite. direction to break the circuit through the terminals 72-73 and 76-77 and establish circuit through the terminals 70-71 and 74-75, reversing direction of current through the armature of. the motor 34 to cause the motor to rotate in reverse direction and return the carriage over the contacts to again out 135 in the resistances, the circuit being then completed through the line 89, brush 85, conductor 90, armature winding 91, mercury tube switch terminals 75 and 74, line 97, motor armature 34, conductor 95, terminals 70 and 71, conductor 140 93, field winding 98, brush 82, conductor 92 to the lead line 86, thus reversing direction of flow through the motor armature 34.

In order to energize the solenoids 64 and 65 remotely of the the mercury tube switches, I provideplsh buttons 99 and 100 connected in circuit to the magnets through the bars 79 and 80, as now described.

The push button 99 is Ior'operating thesolenoid 64 tomove the carriage to the right in cut- 150 switch for effecting operation of ting out the resistances and closes circuit through the conductor 92, a conductor 101 connecting the push button with the wire 92 and the push button with the'contact strip '79 to supply current to the brush 83 which is connected to the coil 64 by a conductor 102. The other lead 0! the coil 64 is connected by-a conductor 103 with the conductor to complete the circuit. 7

The push button is also connected to the conductor 92 and to thecontact strip 80 by a conductor 104 supplying current to the brush 84 which is connected to one of the leads of the coil 65 by conductor 105 and the otherv lead oi the coil is.

connected to the conductor 103 to complete the circuit for that coil.

In order to stop movement of the carriage when it approaches the right hand end of the switch panel, the contact strip '79 terminates short of the other contact strips to break the motor circuit when the brushes operating on the series of contacts are moved onto the last contact, at which point all of the resistances are out of circuit.

In order to stop movement of the carriage in the opposite direction the contact strip 80 is shortened in like manner, and in order to prevent misalignment of the brushes I provide dead contacts 105 and 106 at the terminals 01 the strips to retain the brushes in position.

The resistances of a switch constructed as described are connected together at their left hand ends and the other ends are connected respectively by leads 107, 108 and 109 with the armature terminals or a slip ring motor which is to be controlled by the switch, and which is designated 110 in the drawings, the field winding of the motor being supplied from the wires 86, 8'1 and 88.

In operating a switch constructed and assembled as described, assuming that the carriage is positioned at the left hand side of the switch panel with all of the resistances in circuit, the operator will close the circuit to the magnet coil 64 by pushing the button 99 so that a circuit is completed from the lead line 86, conductor 92, push button 99, contact strip '79, brush 83, conductor 102, magnet 64, conductors 103 and 90, brush 85, contact strip 81, conductor 89 to the other line wire 8'7.

Energization of the coil 64 attracts the armature 99 of the magnet to cause the bell crank levers 48 and 56 to tip the mercury tube switches and close circuit between the terminals '72-'73 and '76-'77, thereby energizing the motor 34 to move the carriage across the contacts, the circuit being established through the lead line 86,

conductor 92,.contact strip '78, brush 82, conductor 93, motor winding 98, terminals '72-'73, conductor 96, motor armature, conductor 95, terminals '7'7 and 76, conductor 90, field winding 91, brush 85, contact strip 81, conductor 89, and lead line 8'7.

The carriage will continue to move across the contacts until the brush 83 rides oi! the contact strip '79 or until the operator breaks the circuit by removing his finger from the push button 99, movement of the carriage gradually cutting out the resistance from the motor circuit until the motor is operating at its maximum or an intermediate speed selected by the operator.

Breaking of the circuit by the push button 99 will cause deenergization oi the magnet coil 64 to permit the armature 58 to swing away from the magnet field pole pieces 60, thereby swinging the mercury tube switches into horizontal position to break circuit between the mercury tube switch terminals to effect deenergization o! the motor windings 91 and 98, whereupon the spring 46 will draw the armature o! the motor out of alignment with the center of the field winding and cause engagement of the brake disk 3'7 with the brake band 45 to prevent coasting oi the carriage over the selected contacts. 7

If the operator then desires to increase the speed of the motor he will again close circuit through the push button 99 to continue forward travel of the carriage, but should he desire to reduce the speed of the motor he will close circuit through the magnet coils 85 by operating the push button 100 which establishes circuit through the-conductor 93, conductor 104, contact strip 80, brush 84, conductor 105, magnet coil 85', conductor '103, brush 85, contact strip 81, conductor 89. the line wire 8'7.

'Energization o! the coil 65 causes the pole pieces of .the magnet 61 to attract the armature. thereby swinging the mercury tube switches in reverse direction to close circuit through the terminals '70-'71 and '74-'75, Circuit is then established through the motor 34 with the current flowing in through the armature in reverse direction, to reverse direction of rotation, thereby bringing more or the resistances into the circuit wires 107, 108 and 109, the circuit to the motor 34 being established through conductor 92, contact strip '78, brush 82, conductor 93, held winding 98, terminals '71-'70, conductor 94, conductor 95, motor armature, conductor 9'7, terminals '74-'75, conductor 90, field winding 91, brush 85, contact strip 81, conductor 88, and lead line 8'7.

When the motor has been reduced to the de- 110 sired speed the operator will remove his finger from the push button 100 to break circuit to the magnet coil 65, allowing the mercury tube switches to return to normal position and breaking circuit to the terminals '71-'72 and '74-'75, thereby stopping operation or the motor 34.

Attention is directed to the fact that as soon as circuit is established through the motor field windings 91 and 92, the armature of the motor will be drawn into the center or the field to re- 180 lease the brake elements to permit rotation of the motor, but when the circuit is interrupted to the field windings the spring 46 will again apply the brake to stop rotation of the motor and prevent coasting ot the carriage over the selected contacts.

While I have described the invention as being employed in connection with a slip ring induction type motor, it is apparent that a switch constructed as described may be used for con- 180 trolling any circuit wherein a rheostat switch is employed. and I do not wish to be limited to the specific arrangement described.

What I claim and desire to secure by Letters Patent is: I

1. In a rheostat switch of the character described, a panel having a series oi electric contacts and a cooperating contact strip extending across its face, rails-extending longitudinally of the panel adjacent opposite side edges thereor, a circuit closing unit mounted on the rails and movable across the contacts including a carriage, means on the carriage controlling circuits through said contacts and contact strip, a motor on the carriage and operable to move the carriage along said rails, and "a reversing mechanism on the carriage controlling the motor.

2. In a rheostat switch 0! the character described, a panel having a series of electric contacts and a cooperating contact strip extending I across its face, rails extending longitudinally of contacts, a rack bar on the panel and extending the panel, a carriage removably mounted on the longitudinally of the'rails, a motor 'on the carrails, means on the carriage controlling circuits riage, means gearing the motor to said rack through said contacts, a motor on the carriage bar for moving the carriage along the rails, 're- 5 and operable'to move the carriage along said versing mechanism on the'carriage for controlrails, a reversing mechanism on the carriage for ling the motor, contact strips on the panel supcontrolling the motor, contact strips on'the panel plying current to said motor, and brushes on supplying current to said motor; and brushes on the carriage contacting said strips and operably the carriage contacting said strips and operably wired to said reversing niecham'sm and said wired to said reversing mechanism and said momotor so that the carriage is removable from tor so that the carriage and its operating mechthe panel without afiecting the wiring.

anismare removable as a ,unit for'replacement 5. A rheostat switch, a panel having electric with another unit without afiectingthe wiring. contacts extending across itsface, rails extend- 3. A rheostat switch, a panel having electric ing across'the top andbottonr of the panel, a s contacts extending across its face, rails extendcarriage removably mounted onsaid rails, means ing longitudinally at the top and bottom of the on the carriage controlling circuits through the panel, a carriage movable over said contacts contacts, a rack bar on the paneland extending rollers operable on said rails to support the carlongitudinally of the rails, a motor on the carriage, means on the carriage controlling circuits riage, means gearing the motor to said rack bar 120 through said contacts, a motor on the carriage for moving the carriage along the rails,'reversing operable to move the carriage along said rails, a mechanism on the carriage for controlling the reversing mechanism on the carriage for conmotor, contact strips on the panel supplying curtrolling the motor, contact stripsonthe 'panel rent to said motor, brushes onthe carriage consupplying current to said motor, and brushes on tacting said strips and operably wired to said thecarriage contacting said strips and operably reversingmechanism and said motor so that the I wired to said reversing mechanism and said mo-. carriage is removable from the panel without tor so that the carriage is removable from the afiecting the wiring, and braking mechanism rails without afiecting the wiring. I I associated with said gearing and operable auto- 4. A rheostat switch, a panel having electric matically upon operation of the reversing mechcontacts extending across its face, rails extendanism to prevent coasting of the carriage on the 1 ing across the top and bottom of the panel, a rails. carriage removably mounted on said rails, means WILLIAM O. DENNIS. on the carriage controlling circuits through the H I i I g I 1;

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