US2036486A - Electric motor control system - Google Patents

Description

April 7, 1936.

R. G, LOCKETT 2,036,486

ELECTRIC MOTOR CONTROL SYSTEM Filed March 4, 1935 -14 14 ig- 1. I H 0 $77 7s-f '89 1:): :1 r3 5 w M w Q isz 0 II -97 i'fi 9 9 I5 ,6 )IZ G as Patented Apr. 7, 1936 ELECTRIC MOTOR CONTROL SYSTEM Ralph G, Lockett, Wauwatosa, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis.,a corporation 01 Delaware Application March 4,

17 Claims.

This invention relates to improvements in electric motor control systems. The invention is particularly applicable to reversing and acceleration control of the driving motor of a rotary washing machine or-the like.

A primary object of the invention is to provide an 'improved and simplified system of control for direct current driving motors of washing machines 'and the like.

Another object is to provide novel means for insuring proper protection to the driving motor during starting while minimizing the time required for effecting acceleration thereof in each instance.

Another object is to minimize the cost'of a control system having the characteristics aforementioned.

Another object is to provide a novel form of control drum for use in a system of the character aforementioned.

Another object is to provide a simple form ofmanually operable means for initiating or interrupting operation of the control system.

Another object is to provide a novel combination of elements including a continuously rotatable drum for automatically effecting operation of the electromagnetically operable reversing and accelerating switches in a predetermined order.

Other objects and advantages of the invention will hereinafter appear.

In the drawing,

Figure 1 illustrates schematically and diagrammatically an electric motor control system as constructed in accordance with my invention, it being understood that the embodiment illustrated is susceptible of modification as to certain de tails of construction thereof without departing from the scope of the appended claims, and

Fig. 2 is a fragmentary view showing a modified form of control drum for use in a system of the character illustrated in Fig. 1.

Referring first to Fig. 1, the numeral 5 designates in general a washing machine of well known form. Said machine as shown comprises an outer tub or casing 6 within which is mounted a. rotatable cylinder designated by the numeral 1. Cylinder I may be of the single compartment type having a single door to be registered with the opening provided in tub 6, said tub having a door 8 to provide for closure of said opening. Cylinder 1 may, of course, be of the type provided with two, three or more radial compartments,-each compartment being provided with a door to be brought into register with the opening in tub 6. Also it is to be under- 1935, Serial No. 9,139

stood that the washer 5 may be of considerably greater horizontal length, and that the cylinder may be provided with any desired number of suitably spaced vertical walls or partitions to afford the desired number of washer compartments,--the tub, of course, being provided with a corresponding number of openings and doors to afford proper access to said compartments.

Cylinder I is connected by shaft 9, reduction gearing I0, and shaft H with the armature of a motor M to be driven by the latter. The series field of motor M is designated by the numeral l2, and the shunt field thereof is designated by the numeral l3,the latter having connected in parallel therewith a well known form of field discharge resistance A pair of resistances l5 and I6 is provided, and the control'means now to be described are adapted to insure initial inclusion of said resistances in circuit in series with the motor armature each time the motor circuit is completed for operation thereof in one direction or the other, and to thereafter insure exclusion of said resistance sections in sequence within a predetermined relatively short period of time. In this manner I insure proper protection for the motor in each instance during starting thereof, while providing for full acceleration thereof within a predetermined minimum period of time.

The control means for motor M comprises a pair of normally open electromagnetically operable reversing switches H and I8, a pair of normally open electromagnetically operable accelerating switches l9 and 20, and a control drum designated in general by the reference character D. Switch ll is provided with normally open main contacts 2| and 22, normally open auxiliary contacts 23 and an operating winding 24. Switch I8 is provided with normally open main contacts 25 and 26, normally open auxiliary contacts 21, and an operating winding 28. Switch I9 is provided with normally open main contacts 29, normally open auxiliary contacts 30, and an operating winding 3|. Switch 20 is provided with normally open contacts 32, andan operating winding 33.

Stationary contacts 34 to 39, inclusive, are provided for cooperative engagement by the segments carried by drum D. The development of drum D is illustrated in the drawing,-it being understood that in practice the left-hand and right-hand edges thereof will be united or connected to provide a drum of cylindrical form. As shown, all of the segments carried by drum D are electrically connected with each other,the

control operation of motor M in the reverse di-' i/eooperate with contacts :4, as, 31, as, and as to I motion.

The left-hand side of drum D is provided with a pair of relatively long segments 43 and 4| of substantially equal dimensions, said segments being vertically spaced from and alined with each other,the same being adapted for cooperative engagement with contacts 34 and 35 as hereinafter described. Positioned beneath the segments 40 and 4| and arranged within the circumferential limits of the latter is a-group of five relatively small or short segments 42 to 46, in-

clusive, which are equally spaced from each other, and adapted for cooperative engagement with contact 36. Engagement of any one of the segments 42 to'46, inclusive, with contact 33 is adapted to provide for energization and closure of switch l'l, assuming prior closure of a manually operable switch 52 by closure of tub door 3.

3 Also positioned beneath. segments 43 and 4| and arranged within the circumferential limits of the latter is a second group of five relatively '30 small segments 41 to SI, inclusive, which are equally spaced from each other, and adapted for cooperative engagement with contact 38. En-- gagement of any one of the segments 41 toll, inclusive, with contact 38 is adapted to provide for energization and closure of accelerating switch |9,--but subject to prior closure of the normally open auxiliary contacts of switch 11. In this connection it is to be noted that segments 41 to 5| are arranged in individually offset and non-overlapping relationship circumferentially of the drum with reference to the respective segments 42 to 46, wherefore a relatively short but predetermined period of time is required to lapse spaced from each other, and adapted for co operative engagement with contact 33. Engagement of any one of the segments 53 to 33-, in-

clusive, with contact 39 is adapted to provide for energization and closure of accelerating switch l||,butsubiect to prior closure of the normally open auxiliary contacts 30 of switch I3. In this connection it is to be noted that segments 33 to 56 are arranged in individually oflset and nonoverlapping relationship circumferentially of the 60 drum with reference to the respective segments 41 to 50, wherefore a relatively short but predetermined period 01 time is required to lapse between closing energization of switch i9 and closing energization of switch 20.

The right-hand side of drum D is provided with.

. 7 of reversing switch |3 in the manner hereinafter described. Ofi'set downwardly from and individually offset circumferentially with respect to segments 59 to 63 is a group of five relatively small segments 64 to 63 which are circumferentially alined with segments 41 to SI, and like- 5 wise adapted for cooperative engagement with contact 38 to provide for closing energization of the winding 3| of accelerating switch l9, but subject to prior closure of the auxiliary contacts 21 of switch I3, as hereinafter described. Offset l0 downwardly from and individually offset-circumferentially with respect to segments 64 to 61 is a group of four relatively small segments 69 to 12, the latter being circumferentially alined with segments 53 to 5,6, and likewise adapted for cooperative engagement with contact 39 to provide for closing energization of the winding 33 of accelerating switch 20, but subject to prior closure of the auxiliary contacts 30 of switch l9, as hereinafter described. 20

As will be apparent, the right-hand and lefthand sides of drum D contain like numbers of segments similarly arranged, with the exception that segments 42 to 46 are adapted for engagement with contact 36, whereas segments 59 to 63 25 are arranged for engagement with contact 31. While I have diagrammatically shown all of the segments ondrum D as electrically connected with each other by suitable wiring, it is to be understood that this result may likewise be at- 30 tained by forming the drum D of conducting material, such as metal, and directly electrically connecting the various segments thereto in any well known manner. For instance, the relatively small segments 42 to 5| and 53 to 56 and 39 to 35 12 may comprise the square heads of bolts the shanks of .which have threaded engagement with the drum cylinder.

Drum D is adapted to be continuously driven unidirectionally (as indicated by the arrow) by a 0 pilot motor 13 which is connected across the direct current supply lines L, L as by means of conductors l4 and 15. A manually operable switch It may be employed if desired to provide for disconnection of motor 13 from the source of 45 I energy supply. I also preferably employ a manually operable switch, shown diagrammatically at 11 and I3, to provide-for disconnection of the entire control system from the source of energy supply L L.

The control system aforedescribed further comprises a plurality of interlocking or currentlimiting resistances I3, 80, 3| and 82, which are interposed between the drum contact 35 and the windings 24, 18, 3|, and 33 of switches ll, I3, I3. 56

and 20, respectively,- whereby upon engagement of segment 4| or segment 53 with contact 33 said windings will be energized to a degree only suflicient .to hold the respective switches closed after full energization of the respective windings there- 60 of, whereas the drumcontacts 33 to 39 and the segments associated therewith cooperate in the manner hereinafter described to effect short- 'circuiting of the resistances 19 to 32 in a predetermined sequence to provide for proper reversing (is and acceleration control of motor M.

Assuming positioning of the several parts as illustrated, and further assuming closure of switch contacts 13, I1, 13 theoperation of the aforedescribed control system is as follows. Upon 70 closure of the switch contacts 52. by closure of tub door 3, with drum D in one of its two ofi'" positions, as illustrated, it is apparent that upon engagement of segments 40 and 4| with contacts 34 and 35. the various windings 24, 23, 3|, '7

-cient degree to efiect closure of their respective switches, due to inclusion in the several circuits of the resistances 19 to 82. However, the short thus closed to complete an energizing circuit for motor M, which circuit maybe traced from line L by conductor 89 through contacts 2| and,

downwardly through the motor armature, thence through contacts 22, resistance sections l5, l5

1 and series field |2 to line L, whereby motor M a so.

is started in one direction atslow speed. Moreover, due to engagement of segment 4| with contact the winding 24 will be maintained energized to a sufficient degree to hold switch l1 closed pending disengagement of segment 4| from contact 35 by continued rotation of drum D.

The auxiliary contacts 23 of switch I] when closed are adapted to preset a circuit for closing energization of the winding 3| of accelerating switch l3 upon-engagement of segment 41 with contact 38. As aforementioned, segment 41 is arranged in circumierentially offset and nonoverlapping relationship'to segment 42, thus requiring lapse 01 a short but predetermined period or time between closing of switch I1 and closing energization of the winding 3| of switch l9. Thus upon engagement of segment 41 with contact 38 the winding 3| is energized by a circuit extending from line L to contact 34, as aioredescribed, thence through segments 40 and 41 to contact 39, by conductor 99 through said winding 3|, conductor 9| through auxiliary contacts auxiliary contacts 30 or switch l9 when closed are adapted to preset a circuit for closing energization of the winding 33 01' switch 29 upon engagement of segment 53- wlth contact 39. Said circuit maybe traced from line L to contact 34, thence through segments 49 and 59 to con-' tact 39, by conductor 93 through said auxiliary contacts 30 and said winding 33, thence by conductor 9|, auxiliary contacts 23, and conductors 92, as, 91, and as to line 1. As aiorenoted segment 53 is arranged in circumferentially offset and non-overlapping. relationship to segment 41 to insure against closure of switch 20 pending lapse of a short but predetermined period or time after closure of switch l9. Upon closure *oiLihe contacts of switch 29 resistance J5 is excludedbya connection shunting both of the resistances |5and I6, whereby the armature of motor M is connected directly across lines U, L

for full speed operation thereof. Thereafter winding 33 will be sufliciently energized, by a circuit extending through contact'34, segments P ina el, contact 33- and resistance 82,- to hold switch 20 closed pending disengagement oi segment 4| from contact 35.

Due to continued rotation of dlllxhiD segments 40 and 4| will eventually be disengaged from contacts '34 and 35, and all other segments at the left-hand side of the drum will likewise be disengaged from their cooperating contacts, with the result that complete de-energization of the operating windings of the aforementioned switches |1, I9, and 20 is insured, to interrupt the energizing circuit of the armature of motor M. Within a relatively short predetermined period of time thereafter the segments 51, 58, and 59 at the right-hand sideof drum D will simultaneously engage contacts 34, 35, and 31, thereby completing a circuit for closing energization of the winding 29 of reversing switch l9. Said circuit may be traced from line L to contact 34, in the manner atoredescribed, thence through segments 51 and 59 to contact 31, by conductor 94 through said winding 28, and by conductors 81 and 88 to line U.

The main contacts 25 and 26 when closed complete a circuit for the armature of motor M,

I said'circuit extending from line L by conductor 95 through contacts 25, by conductor r-ilfi upwardly through said armature, thence through. contacts 25, and by conductor 91 through resistances l5, I5 and series field |2 to line U. Thereafter drum D acts through segment 59, contact 35 and current-limiting resistance 80 to provide a suflicient degree or energization oi winding 28 to maintain switch l9 closed pending disengagement of segment 58 from segment 35.

The auxiliary contacts 21. of switch |8 when closed are adapted to preset a circuit for closing 9| through said contacts 21, and by conductor 98 toline I As will be noted, segment 84 is arranged in circumi'erentially offset and nonoverlapping relationship to segment 59, thus requiring i.

lapse of a short but predetermined period of time between closing of switch I8 and closing energization of the winding 3| of switch I9. After switch I9 is closed the winding 3| will be energized sufliciently to maintain the same-closed through the medium of resistance 8|, pending disengagement of segment 59 from contact 35.

The main contacts 29 of switch l9 when closed act in the manner aforedescribed to effect exclusion of resistance section l5 from the armature circuit of motor M. The auxiliary contacts 39 01' switch |9 when closed are adapted to preset a circuit for closing energization of the winding 33 f of switch 29 upon engagement of segment 69 with Said circuit may be traced from line contact 39. L to contact 34, thence through segments 51 and E9 to contact 39, by conductor 93 through said auxiliary contacts 30 and said winding 33, thence by conductor 9|, auxiliary contacts 21, and by conductor 98 to line L As aforenoted segment 89 is arranged in circumicrentially offset and nonoverlapping relationshipto segment 54 to insure against closure of switch 20 pending lapse of a short but predetermined period of time after clo sure of switch l9. Closure of the contacts 32 of switch 20 results, as aforedescribed, in exclusion of resistance l6 by a connection shunting both of the resistances l5 and I3, whereby the armature of motor M is connected directly across lines L L. Thereafter winding 33 will be sufficiently energized, by a circuit extending through contact 34, segments 51 and 58, contact 35 and resistance 82, to hold switch 20 closed pending disengagement of segment 56 from segment 35.

By reason'of the continuous operation of pilot motor TS it is to be understood that drum D may be in any angular or rotary position at the instant the contacts 52 are closed by closure of the tub door 8. If the left-hand side of drum D happens to be in cooperative relationship to the contacts 34 to 39, whichever one of the group of segments 42 to first engages contact 36 will cause closing energization of the operating winding of forward switch I1, and said switch will be maintained closed pending such movement of drum D as will effect disengagement of segment 4| from contact 35. Prior engagement of one of the group of segments 41 to 5| with its cooperating contact 38 or engagement of one of the group of segments 53 to 56 with its cooperating contact 39 will have no controlling effect upon the windings 3| and 33 of accelerating switches 43 and 20, due to the electrical interlock provided by the aforementioned auxiliary contacts 23 of switch ll. Also, as aforedescribed, the provision of auxiliary contacts 38 on switch I9 insures against closure of switch 20 prior to closure of switch IS. The segments at the right-hand side of drum D cooperate in a like manner with the respective contacts to insure closure of switches l8, l9, and 20 in the desired sequence.

As will be apparent to those skilled in the art, the number of accelerating resistances l5, [6 may be increased or decreased if desired, with a corresponding change in the number of accelerating Switches and drum segments and contacts for controlling the same. Inasmuch as the switch is must be closed as a prerequisite to closure of switch 20, it is obvious that the contacts 32 of the latter may be arranged to provide for shortcircuiting of resistance section I6 only, instead of the particular arrangement herein illustrated.

By the means aforedescribed I am enabled to insure substantially instantaneous starting of motor M by merely closing the tub door 8, the inclusion of starting resistances l5, IS in the motor circuit being insured, and proper acceleration of the motor by sequential exclusion of said resistances l5, I6 within a predetermined relatively short period of time being likewise insured under all conditions.

In practice it is preferred to operate the drum D at a speed of between one and one-eighth and two and one-half revolutions per minute. The importance and advantages of the system of control herein described are therefore apparent,

inasmuch as the same insures a multiplicity of accelerating points around the drum, wherefore only a relatively short period of slow speed opera tion of'the driving motor is'required upon starting thereof, regardless of the angular position of the control drum at the instant of starting. Also as will be apparent from the foregoing description while the multiplicity of accelerating points are individually effective during starting of the motor in each instance, those points not required to be utilized are automatically rendered temporarily ineffective for controlling the operation of the driving motor.

If the door of cylinder 1 is not properly regist .rc with the opening in tub 6 at the time when the cylinder is brought to rest, it is obvious that further movement of the-cylinder at slow speed may be effected by temporarily closing tub door 8. whereby the tub door switch is utilized for with the former.

effecting inching of motor M. In practice, however, it may be desirable to provide a normally open push button switch (not shown), shunting the contacts 52 of the tub door switch, to provide for inching control of motor M while the tub door 5 8 remains in open position.

The modified form of control drum D shown in Fig. 2 performs exactly the same functions as the drum D shown in Fig. 1 and may be substituted therefor if desired. Drum D preferably 10 has a circumference equal to that of drum D. Also as will be noted drum D may be substantially shorter, axially, than drum D. Certain of the parts employed in constructing drum D may be utilized in producing drum D and correl5 sponding parts are given like numerals of reference in the two figures. Thus I have shown in Fig. 2 the contact fingers 34, 35, 36, 33, and 33 which are adapted to cooperate with drum segments 40 to 5| and 53 to 56 identical with those 20 shown at the left-hand side of drum D in Fig. 1.

The contact finger 31 in Fig. 2 is circumferentially alined with and diametrically opposed to contact finger 36, wherefore the segments 42 to 46 of Fig. 2 additionally serve to perform the func- 25 tions of the segments 59 to 63 at the right-hand side of drum D in Fig. l. Circumferentially alined with and diametrically opposed to contact fingers 34, 35, 38, and 39 in Fig. 2 are a corresponding number of contact fingers 34, 35, 38-,

39*, which are respectively electrically connected As will be understood, the segments 40 to 5| and 53 to 56 occupy substantially one-half of the circumferential area of drum D the other half of the drum circumference being free from segments. The arrangement is such that after the segments to 5| and 53 to 56 have moved out of cooperative engagement with fingers 3 to 36, 38 and 39, the

samewill, in a like manner, cooperatively en- 40 gage the contact fingers 34', 35, 31, 38, and 39, respectively, to perform control functions identical with those performed by the segments 51 to 12 at the right-hand side of drum D in Fig. 1.

The contact fingers of drum D are electrically connected to the various control elements in the same manner as in the fingers of drum D in Fig. 1, as indicated by the several conductors 63, 85, 94, 96, and 93. The resistances 19 to 62 in Fig. 2 are identical with those shown in Fig. 1.

From the foregoing it will be seen that the drum I D in Fig. 2 requires only one-half as many segments as (or sixteen less than) the drum D in Fig. 1, whereas only four more contact fingers are required for drum'D than are required for 56 drum D. The advantages of the arrangement illustrated in Fig. 2 will therefore be apparent to those skilled in the art. The operation of drum D and the functions performed thereby are believed to be obvious from the detailed description 60 of the device illustrated in Fig. 1.

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

' l. The combination with an electric motor, of

a device to be rotatably driven thereby, a pair of 5 electromagnetically operable switches adapted to be energized selectively to provide for forward or reverse operation of said motor, resistance to" be included in circuit with said motor upon energization and closure of either of said switches,

first mentioned, and means for initiating operation of said motor in one direction or the other within a relatively short period of time and for timing the operation of said resistance-excluding switch, said means comprising a manually operable switch associated with said driven device and a continuously operable unidirectionally rotatable pilot drum, said drum having cooperating contacts and segments to provide for periodic reversal of said motor and to provide for operation of said resistance-excluding switch. within a predetermined relatively short period of time after completion of the circuit for the motor regardless of the instantaneous direction of operation oi the latter.

2. In a control system for motor driven washing machines and the like, the combination with a rotatable container, of an electric driving motor therefor, a pair of normally open electromagnetically operable switches adapted when closed selectively to provide forward and reverse circuit connections respectively for said motor, starting resistance to be included in circuit with said motor upon closure of either of said switches, means comprising a normally open electromagnetically operable switch adapted when closed to effect exclusion of said resistance a driving connection with said drum, said drum having cooperating contacts and segments adapted when rendered effective to provide ior energization and closure of one of said first mentioned switches within a predetermined relatively short period of'time regardless of the instantaneous rotary positionof said drum, associated means to provide for maintaining said one of said switches closed pending a given operation of said drum to effect reversal of the motor circuit connections, and a switch associated with said rotatable container; said last mentioned switch being manually operable to render said drum contacts and segments effective or inefiective at will to provide for completion or interruption of the,

motor circuit connections.

3. In a control system for motor driven washing machines and the like, the combination with a rotatable container, an electric driving motor therefor, a pair of normally open electromagnetically operable switches adapted when closed selectively to provide forward and reverse circuit connections respectively for said motor,

starting resistance to be included in circuit with said motor upon closure of either of said switches, means comprising a normally open electromagnetically operable switch adapted when closed to effect exclusion ofsaid resistance from the motor circuit, means comprising an electrical interlock to insure energization and closure of one of said first mentioned switches prior to energization and closure of said last mentioned switch, a uni directionallyoperable drum, a continuously operable pilot motor having a driving connection with said drum, said drum having cooperating contacts and segments adapted when rendered effective to provide for energization and closure of one of said first mentioned switches within a predetermined relatively short period of time reto provide for energization and closure of said re sistance-excluding switch within a predetermined relatively short period of time after energize.- tion and closure or said one of said first mentioned switches, associated means to provide for maintaining said one of said switches and said resistance-excluding switch closed pending a given operation of said drum to efiect reversal of the motor circuit connections, and a manually operable switch associated with said rotatable container, said last mentioned. switch being operable to render said drum contacts and segments effective or ineifective at will to provide for completion or interruption of the motor circuit connections.

4. The combination with an electric motor, of a device to be rotatably driven thereby, a pair of electromagnetically operable switches adapted to be energized selectively to provide for forward or reverse operation of said motor, resistance to be included in circuit with said motor upon energization and closure of either of said switches, a third electromagnetically operable switch to be energized for effecting exclusion of said resistance, means including sets of normally open auxiliary contacts carried by the respective switches first mentioned, said auxiliary contacts being adapted to insure against energization and closure of said last mentioned switch prior to energization and closure of one of said switches first mentioned, means for initiating operation of said motor in one direction or the other and for timing the operation of said resistance-excluding switch, said means comprising a manually oper= able switch associated with said driven device and a continuously operable unidirectionally rotatable pilot drum, said drum having a group of equally spaced circumferentially alined segments, a contact adapted when engaged by any one of said segments to effect energization and closure of one of said first mentioned switches subject to prior closure of said manually operable switch, a second group of equally spaced circumferen tially alined segments axially spaced from said first mentioned group, and a contact adapted when engaged by any one of said last. mentioned segments to efject energization and closure oi said resistance-excluding switch subject to prior closure of said one of said first mentioned switches, the segments of said second group be ing circumferentially offset relatively to the respective segments of the group first mentioned to thereby provide for lapse of a predetermined period of time between closure of said one of said first mentioned switches and said resistance-exeluding switch.

5. The combination with an electric motor, of a device to be rotatably driven thereby, a pair of electromagnetically operable switches adapted to be energized selectively to provide for forward or reverse operation of said'motor, resistance to be included in circuit with said motor upon energization and closure of either of said switches, a third e'lectromagnetically operable switch to be energized for effecting exclusion of said resistance} means including sets of normally open auxiliary contacts carried by the respective switches first mentioned, said auxiliary contacts being adapted to insure against energization and closure of said last mentioned switch prior to energization and closure of one of said switches first mentioned, means for initiating operation of said motor in one direction or the other and for timing the operation of said resistancewxcluding switch, said means comprising a manually operable switch associated with said driven device and a continuously operable unidirectionally rotatable pilot drum, said drum having a group of equally spaced circumferentially alined segments, a contact adapted when engaged by any one of said segments to effect energization and closure of one of said first mentioned switches subject to prior closure of said manually operable switch, a second group of equally spaced circum-- ferentially alined segments axially spaced from said first mentioned group, a contact adapted when engaged by any one of said last mentioned segments to effect energization and closure of said resistance-excluding switch subject to prior closure of said one of said first mentioned switches, the segments of said second group being circumferentially offset relatively to the respective segments of the group first mentioned to thereby provide for lapse of a predetermined period of time between closure of said one of said first mentioned switches and said resistance-excluding switch, said drum also having a third group of equally spaced segments circumferentially alined with each other and opposed to and axially offset from the groupof segments first mentioned, and a contact adapted when engaged by any one of said last mentioned segments to effect energization and closure of the other of said first mentioned switches under the conditions aforestated.

6. The combination with an electric motor, of a device to be rotatably driven thereby, a pair of electromagnetically operable switches adapted to' be energized selectively to provide for forward or reverse operation of said motor, resistance to be included in circuit with said motor upon energization and closure of either of said switches, a third electromagnetically operable switch to be energized. for effecting exclusion of said resistance, means including sets of normally open auxiliary contacts carried by the respective switches first mentioned, said auxiliary contacts being adapted to insure against energization and closure of said last mentioned switch prior to energization and closure of one of said switches first mentioned, means for initiating operation of said motor in one direction or the other and for timing the operation of said resistance-excluding switch, said means comprising a manually operable switch associated with'said driven device and a continuously operable unidlrectionally rotatable pilot drum, said drum having a group of equally spaced circumferentially alined segments, 8. contact adapted when engaged by any one of said segments to effect energization and closure of one of said first mentioned switches subject to prior closure of said manually operable switch, a second group of equally spaced circumferentially alined segments axially spaced from said first mentioned group, a contact adapted when engaged by any one of said last mentioned segments to effect energization and closure of said resistance-excluding switch subject to prior closure of said one of said first mentioned switches, the segments of said second group being circumferentially offset relatively to the respective segments of the group first mentioned to thereby provide for lapse of a predetermined period of time between closure of said one of said first mentioned switches and said resistance-excluding switch, said drum also having a third group of equally spaced segments circum- Ierentially alined with each other and opposed to and axially offset from the group of segments first mentioned, a contact adapted when engaged by any one or said last mentioned segments to efiect energization and closure of the other of said first mentioned switches under the conditions aforestated, and said drum also having a fourth group of equally spaced segments circumferentially alined with the segments of said sec- 0nd group and cooperating with the contact associated with the latter to likewise effect energization. and closure of said resistance-excluding switch subject to prior closure of the other of said switches first mentioned.

'7. As an article of manufacture, a pilot control drum including a. multiplicity of segments all of which are electrically connected with each other, said segments comprising two pairs of relatively long segments of substantially equal dimensions, the segments of each pair being vertically spaced from and alined with each other and said pairs being arranged in slightly spaced and endwise alined relationship to each other circumferentially of the drum, two groups of directional switchcontrolling segments, the segments of each group being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of the pairs oi segments first mentioned, said two groups of segments being arranged in offset relationship axially of the drum, two groups of ac-' in the circumferential limits of the pairs of segments first mentioned, and the segments of said last mentioned groups being arranged in circumierentially ofiset and non-overlapping relationship to the segments of the respective groups first mentioned, for the purpose set forth.

8. In combination, a pilot control drum including a multiplicity of segments all of which are electrically connected with each other, said segments comprising two pairs of relatively long segments of substantially equal dimensions, the segments of each pair being vertically spaced from and alined with each other and said pairs being arranged in slightly spaced and endwise alined relationship to each other circumferentially of the drum, two groups of directional switch controlling segments, the segments of each group being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of the respective pairs of segments first mentioned, said two groups of segments being arranged in offset relationship axially of the drum, two groups of accelerating switch controlling segments arranged in alinement with each other circumferentially of the drum, the segments of each group last mentioned also being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of the respective pairs of segments aforementioned, the segments of said last mentioned groups being arranged in circum tially offset and non-overlapping relationship to the segments 0! the respective groups first mentioned, a pair of normally open electromagnetically operable directional switches and a normally open electromagnetically operable resistance-excluding switch, a plurality of contacts adapted for cooperation with said drum segments, one of said contacts being connected with a suitable source of energy supply, saidcontact being sequentially engageable by one of the segaosassc a ments of each of said pairs, another of said con= tacts being connected through a corresponding number of current-limiting resistances with the operating windings of the directional switches and said resistance-excluding switch respectively, said last mentioned contact being sequentially en gageable by the other of the segments of each of said pairs, said resistances being calibrated to permit only sufficient energization of, the operat ing windings of the respective switches to maintain the latter closed after full energization of the respective windings, any one of the segments of one of the two groups first mentioned being cooperable with another of said contacts to effect short-circuiting of one of said resistances to provide for full energization of the winding of one of said directional switches. any one of the segments of the other of the two groups first mentioned being cooperable with another of said co tacts to effect short-circuitlng of another of said resistances to provide for full energization of the winding of the other directional switch, and any one of said two groups of accelerating switch controlling.segments being cooperable wi h an other of said contacts to efiect short-circuiting of ano her of said resistances under predetermined conditions to provide for full energization of the winding of said resistance-excludingswitch.

9. In comb na i a lot ontrol dru including a multiplicity of. se ments all or" which are electrically connected w th each oth r. a d se ments com rising two pairs of relatively lon segments of substantially eo'u l dim ns on the segments of each pair being vert cally soac dfrom and alined w th each other and said p irs b ing arranged in slightly spaced and endwise alined relationship to each other circum'feren tially of the drum, two groups of directional switch controlling segments, the segments of each group being relatively small and the same being arranged in eoually spaced relat onship to each other within the circumferential limits of the respective pairs of segments first .n'ientionedv said two groups of se ments being arran ed in offset relationship axially of the drum, two roups of accelerating switch controlling segments arranged in alinement with each other circumierentially of the drum, the segments of each group last mentioned also being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of the respective pairs of segments afore mentioned, the individual segments of said last mentioned groups being arranged in circumferentially offset and non-overlapping relationsh p to the segments of the res ective groups first mentioned, a pair of normally open electromagnetically operable directional switches and a normally open electromagnetically operable res stance-excluding switch, means comprising a set of normally openauxiliary contacts associated with each of said directional switches and requiring energization and closure of one of the latter as a pre-requisite to closing energization of said resistance-excluding switch, a plura ity of contacts adapted for cooperation with said drum segments, one of said contacts being connected with a suitable source of energy supply, said contact being sequentially engageable by one of the segments of each of said pairs, another of said contacts being connected through a corre sponding number of current-limiting resistances with the operating windings of the directional switches and said resistance-excluding switch, re== spectively, said last mentioned contact being sequentially engage-able by the oth r of the segments of each of said pairs, said' resistances being calibrated to permit only sufficient energizetion of the operating windings of the respective switches to maintain the latter closed after full energization of the respective windings, any one of the segments of one of the two groups first mentioned being cooperable with another of said contacts to effect short-circuiting of one ofsa d resistances to provide for full energization oi the winding of one of said directional switches, any onset the segments of the other of the two groups first mentioned being cooperable with another of said contacts to effect short-circuiting of another of said resistances to provide for full energization of the winding of the other directionsl switch, any one of said two groups of accelerating switch controlling segments being cooperable with another of said contacts to effect short circuiting of another of said resistances, subject to prior energization and closure of one of said directional switchesfto provide for full energization of the winding of said resistanceescludlng switch, and a single manually controlled switch operable to render said drum contacts and segments effective or ineffective at will.

10. in a control system of the character described, in combination, a rotatable device, an electric motor having a driving connection with said device, a pair of normally open electromag netically operable switches one or" which is adapted upon closure thereof to effect operation of said motor in one direction and the other of which is adapted upon closure thereof to effect operation of said motor in the reverse direction. resistance to be included in circuit with said motor upon closure of either of said switches, a third electromagnetically operable switch adapted upon closure thereof to effect short-circuiting of said resistance wh reby said motor is accelerated, means for insuring against closure of said third switch pending closure of one of said pair of switches first mentioned, means comprising continuous- 1y operable unidirectionally rotatable drum, said drum normally operable to effect energizeticn and closure of said pair of switches alternately for predetermined periods oi time and to time the energization and closure of said third switch with. respect to each of said pair of switches. each of said switches having a current-limiting resistance associated with the operating winding thereof and said drum having contacts and segments so arranged as to provide for intermittent short-circuiting of said resist ences selectively, whereby said motor be started in one direction or the other and accelerated within a predetermined relatively short period of time regardless of the instantaneous rotary position of said drum, and single manually operable switch associated w said stat able device and operable to ren said re effective or ineffective at will for controlling said electromagneticolly operable switches.

ii. The combination with a reversible electric driving motor, of control means therefor com prising a pair of electromagnctically operable re-- versing switches and a pair of elcctromagnetically operable accelerating switches, a pair of resistance sections to be included circuit with said motor upon closure of either said reversing switches, means to insure against energize,- ticn one of said accelerating switches pending closure of one or "the other of said reversing switches, said means comprising a set of normally open auxiliary contacts carried by each of said reversing switches, said auxiliary contacts being connected in parallel relation with each other in series 'with the operating winding of said accelerating switch, means to insure against energization of the other of said accelerating switchs pending closure of said accelerating switch first mentioned, said means comprising a set of normally open auxiliary contacts carried by said accelerating switch first mentioned, said auxiliary contactsbeing connected in series with the operating Winding of said second mentioned accelerating switch, a control drum adapted to rotate continuously in one direction, a single manually operable switch adapted when closed to render said drum effective, said drum having cooperat-- ing contacts and segments adapted'to provide for energization and closure of one or the other tacts and the operating windings of each of said reversing and accelerating switches to initially prevent closing energization of said windings while providing for maintenance thereof in closed ly operable accelerating switches, a pair of rev 'sistance sections to be included in circuit with said motor upon closure of either of said reversing switches, means to insure against energization of one of said accelerating switches pending closure of one or the other of said reversing switches, said means comprising a set of normally open auxiliary contacts carried by each of said reversing switches, said auxiliary contacts being connected in parallel relation with each other in series with the operating winding of said accelerating switch, means to insure against energizaticn'of the other of said accelerating switches pending closure of said accelerating switch first mentioned, said means comprising a set of normally open auxiliary contacts carried by said accelerating switch first mentioned,'said auxiliary contacts being connected in series with the operating winding of said second mentioned accelerating switch, a control drum adapted to rotate continuously in one direction, a single manually operable switch adapted when closed to render said drum effective, said drum having cooperating contacts and segments adapted to provide for energization and closure of one or the other of said reversing switches within a predetermined relatively short period of time regardless of the instantaneous rotary position of said drum, said drum also having cooperating contacts and segments to provide for energization and closure of said. accelerating switches in a predetermined timed relation to each other within a predetermined relatively short period. of time after clomay be stopped at will.

sure of said reversing switches respectively, current-limiting resistances respectively interposed between one of said drum contacts and the operating windings of each of said reversing and accelerating switches to initially prevent closing energization of said windings while providing for maintenance thereof in closed position throughout a predetermined cycle upon temporary shortcircuiting of the respective resistances last mentioned trn'ough the medium of other of said drum contacts and segments, said drum contacts and segments also acting to periodically effect reversal and acceleration of said motor in the manner aforedescribed, and said manually operable switch being adapted when opened to render said control drum ineiiective, whereby said. motor 13. In a control system oi. the character described, in combination, a rotatable device, an

electric motor having a driving connection with said device, a pair of normally open electromagnetically operable reversing switches and a pair of normally open electromagnetically operable accelerating switches for effecting control of said motor, control means for said switches compris- I, ing a manually operable switch associated wlth said rotatable device and a continuously 0perable unidirectionally rotatable drum, means operable independently of said drum to insure against closure of one of said accelerating switches prior to closure of one or the other of said reversing switches, means also operable independently ofsaid drum to insure against closure of the other of said accelerating switches prior to closure of said accelerating switch first mentioned, said drum having cooperating contacts and segments so arranged as to provide for energization and closure of one or the other of said reversing switches within a predetermined relatively short period of time regardless of the instantaneous rotary position of said drum, and said contacts and segments also acting thereafter to effect sequential energization and closure of said accelcrating switches within a predetermined relatively short period of time, whereby the period of slow speed operation of said motor upon starting thereof in either direction is minimized.

14. In a control system of the character described, in combination, a rotatable device, an

. electric motorhaving a driving connection with said device, a pair of normally open electromag- "netically operable reversing switches and a pair of normally open electromagnetically operable accelerating switches for efiecting control of said motor, control means for said switches comprising a manually operable switch associated with said rotatable device and a continuously operable unidirectionally rotatable drum, means operable independently of said drum to insure against closure of one of said accelerating switches prior to closure of one or the other of said reversing switches, means also operable independently of said drum to insure against closure of the other of said accelerating switches prior to closure of rotary position of said drum, said contacts and segments also acting thereafter to eifect sequential energization and closure of said accelerating switches within a predetermined relatively short 76 period of time, whereby the period of slow speed operation of said motor upon starting thereof in either direction is minimized, and means associated with said drum contacts and segments and said electromagnetically operable switches and adapted upon closure of one or the other of said reversing switches and said accelerating switches to normally maintain the same closed pending operation of the drum to one of a number of predetermined rotary positions preparatory to reversal of the motor circuit connections.

15. In a control system of the character described, in combination, a rotatable device, an electric motor having a driving connection with said device, a pair of normally open electromagnetically operable reversing switches and a pair of normally open electromagnetically operable accelerating switches for effecting control of said motor, control means for said switches comprising a manually operable switch associated with said rotatable device and a continuously operable unidirectionally rotatable drum, means operable independently of said drum to insure against closure of one of said accelerating switches prior to closure of one or the other of said reversing switches, means also operable independently of 'said drum to insure against closure of the other of said accelerating switches prior to closure of said accelerating switch first mentioned, said drum having cooperating contacts and segments so arranged as to provide for energizati n and closure of one or the other of said reversing switches within a predetermined relatively short period of time regardless of the instantaneous rotary position of said-drum, said contacts and segments also acting thereafter to effect sequential energization and closure of said accelerating switches within a predetermined relatively short period of time, whereby the period of slow speed operation of said motor upon starting thereof in either direction is minimized, means associated with said drum contacts and segments and said electromagnetically operable switches and adapted upon closure of one or the other of said reversing switches and said accelerating switches to normally maintain the same closed pending operation of the drum to one of a number of predetermined rotary positions preparatory to reversal of the motor circuit connections, said last mentioned means comprising a corresponding number of current-limiting resistances interposed between the operating windings of the respective electromagnetically operable switches and one of said drum contacts, and means including other of the drum contacts and segments for temporarily effecting short-circuiting of said resistances in a predetermined order.

16. As an article of manufacture, a pilotdTifi trol drum including a multiplicity of segments all of which are electrically connected with each other, said segments comprising a; pair of relatively long segments of substantially equal dimensions, the segments of said pair being vertically spaced from and alined with each other, a group of directional switch controlling seg-' ments, the segments of said group being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of said pair of segments, two groups of accelerating switch controlling segments, the segments of each group last mentioned also being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of said pair of segments, and the segments of one of said last mentioned groups being arranged in circumferentiallyofiset and non-overlapping relationship to the segments of the other of said last mentioned groups and to the segments of the group first mentioned, for the purpose set forth.

17. As an article of manufacture, a pilot control drum including a multiplicity of segments all of which are electrically connected with each other, said segments comprising a. pair of relatively long segments of substantially equal dimensions, the segments of said pair being vertically spaced from and alined with each other, a group of directional switch controlling segments, the segments of said group being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of said pair of segments, two groups of accelerating switch controlling segments, the segments of each group last mentionedalso being relatively small and the same being arranged in equally spaced relationship to each other within the circumferential limits of said pair of segments, the segments of one of said last mentioned groups being arranged in circumferentially offset and non-overlapping\ relationship to the segments of the other of said last mentioned groups and to the segments of the group first mentioned, for the purpose set forth, five pairs of contact fingers, the contact fingers of each pair being diametrically opposed to each other and said pairs being circumferentially alined with said relatively long segments and with said groups of segments respectively, the pair of contact fingers associated with said group of directional switch controlling segments having electrical connections individual thereto respectively, and the contacts of each of said other pairs being electrically connected with each other.

RALPH G. LOCKE'IT.

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