US1794736A - Motor controller - Google Patents

Description

1931- E. w. SEEGER 1,794,736

MOTOR CONTROLLER Filed March 29, 1926 INVENTOR.

ATTORNEY Patented Mar. 3, 1931 UNITED STATES PATENT OFFICE EDWIN w. BERGER, 0] SOUTH MILWAUKEE, WISCONSIN, ASSIGNOB, BY IESNE AS- SIGNIENTS, '10 CUTLER-wk ma, 0! MILWAUKEE, WISCONSIN, A CORPORA- TION OF DELLWAIB-I IOTOB CONTROLLER This invention relates to improvements in motor controllers and more particularly to shunt field controllers for direct current motors.

An object of the invention is to rovide simplified means for effecting step y ste commutation of the resistance to be include in or excluded from the shunt field circuit.

Another object is to provide for control of said resistance through a pluralit of switches of like construction, means eing provided for insuring operation of the respective switches in proper sequence to efi'ect a graduated increase or decrease in the strength of the shunt field.

Another object is to provide simple and etficient means for importing an appreciable time element of response in th operation of the individual switches contro lin the respective sections of resistance in t e shunt field circuit.

Other objects and advantages of the invention will hereinafter appear.

In the drawing I have illustrated certain embodiments which m invention may assume in practim and t e same will now be described, it being understood that the invention may assume other forms falling within the scope of the appended claims.

In thedrawing,

Figure 1 is a schematic and dia atic illustration of a controller embodying the invention; and

Fig. 2 similarly illustrates a modified form of controller constructed in accordance with the invention.

Referring to Fig. 1, A desi ates the armature of a compound woun direct current motor, the series field winding thereof being indicated at F and the shunt field winding thereof being indicated at F. The armature A and series field F are adapted to be connected across lines L L by any suitable form of starting switch, the electroresponsive starting switch S as shown being provided with a plurality of movable contact elements or fingers 5, 6 and 7 for engagement with stationary contacts 8, 9 and 10 to initially include inand sequentially exclude from the armature and series field circuit suitable steps of starting resistance R and R Switch S is normally biased to open position, and the same is provided with an operating coil 11, the energizing circuit of which is completed upon movement of the contactor 12 of a manual control switch MC into engagement with the contact segment 13, as shown in dotted lines at a. Switch S is also referably provided with a dashpot device 14 or retardmg the movement of contact fingers 5, 6 and 7 into and out of engagement with contacts 8, 9 and 10, respectivel During startin o the motor in the manner aforedescribed ull strength of the shunt field F is provided through norm-all closed positioning of contacts 15, 16 an 17 of electroresponsive switches S S and S,'respectively, whereby the shunt field weakening resistance sections R, R and R are short circuited. Switches S, S and S are respectively provided with operating coils 18, 19 and 20. I I

Thus, to effect high speed operation of the motor after attainment of normal speed thereof, arm 12 of switch MC may be moved to dotted line position 6, into engagement with contact segment 21, thereby providing an energizing circuit for coil 18 of switch S. Contact 15 t ereupon opens to interru t the short-circuit around resistance section 2 and coil 19. Resistance R and coil 19 will thus be included in circuit in series with each other and in series with shunt field F Contact 16 then opens due to operating energization of coil 19, whereby resistance sections R and R and coils 19 and 20 are connected in series with eachother and in series with field F. In like manner coil 20 effects opening of contact 17 whereby each of the resistances R R and R and the associated coils 19 .and 20 are included in circuit in series with field F By the arrangement aforedescribed an apreciable time interval elapses between openmg of the res ective contacts 15, 16 and 17 of switches S, 8 and S due to the inherent time lag incident to the inductance of the coils 18, 19 and 20 thereof. In other words, the inductive effect of the shunt field winding F is utilized to increase the time element of response of switches S and S without necessitating an increase in the size of the operating coils 19 and 20 of the latter and without necessitating addition of any elements whatsoever to the control mechanism. Inclusion of resistance sections R, R and R in positive steps is thus insured. Moreover, an effective but less pronounced time element of resiponse of switches S S and S is prod during the operation of excluding resistance sections R, R and R from the circuit of field F Thus, upon movement of arm 12 from dotted line position b to position a the energizing circuit of coil 18 1S interrupted, which efiects simultaneous short-circulting of resistance section It and coil 19 through reclosure of contact 15. The consequent reclosure of contact 16 effects simultaneous short-circuiting of resistance section IR and coil 20, whereas subsequent reclosure of contact 17. effects short-circuiting of resistance section B; field F being then connected directly across lines L L through contacts 15, 16 and 17. The motor will then run at normal speed pending movement of contact 12 of switch MC to the full line position shown, which results in deenergization of coil 11 of switch S. Contacts 7 6 and 5 will thereupon open sequentially to first reinclude resistance section R in circuit, then sections R and R, and then efiect opening of the armature circuit through disengagement of contacts 5 and 8.

By the arrangement aforedescribed I provide for simple and positive control of the shunt field acceleration and deceleration, the means employed being operable automatically to insure the desired time element of response thereof without the use of electrical interlocks.

The construction illustrated in Fig. 2 is in many respects substantially like that shown in Fig. 1, and corresponding parts have been given like characters of reference. It will e noted, however, that the electroresponsive switches S S and S of Fig. 2 are of the normally open type, the normally open contacts thereof being designated by numerals 22,23 and 24, respectively. Said switches are provided with o crating coils 18, 19 and 20, respectively; an the contact segment 21 controlling coil 18 is arranged to be engaged by contactor 12 upon movement of the latter to dotted line position a.

In this manner the contacts 22 of switch S are adapted to be closed substantially simultaneously with the closure of contacts 5 and 8 of starting switch S and upon closure of said contacts 22 coil 19 will be connected across resistance section R thereby short-circuiting the latter. With coil 19 thus energized closure of contacts 23 of switch S is effected to include coil 20 in circuit across resistance section R, thereby short-circuiting the latter. The resulting energization of coil 20 efl'ects closure of contacts 24 to short-circuit resistance section B, whereupon shunt field winding circuit of coil 18 of switch S and the contacts 22 of the latter in opening efiect reinclusion of resistance section B. in circuit with field F Contacts 22 in opening also eliect interruption of the energizing circuit of coil 19 of switch S, whereupon the contacts 23 of the latter in opening eflect reinclusi-on of resistance section B. in circuit in series with field F and resistance section R Contacts 23 in opening also efi'ect interruption of the energizing circuit of coil 20 of switch S whereupon the contacts 24 of the latter are opened to effect reinclusion of resistance section B in circuit in series with field F and resistance sections R and R.

Moreover, deceleration of the motor to normal speed may be effected by reverse movement of contactor 12 to dotted line position a, resulting in sequential exclusion of resistance sections R R and It from the circuit of shunt field winding F throughv sequential reclosure of contacts 22, 23 and 24,,

' winding. That is to say, upon closure of contacts 22 of switch S to short circuit resistance R the inductance of field winding F will appreciably increase or augment the time element of response of switch S. Thus with field F in an initially weak conditions due to inclusion of resistances R R and R in series therewith, obviously upon exclusion of resistance section It the inductance of winding F will retard or oppose passage of the increased value of current therethrough. Since the building up of the value of current traversing winding F is thus retarded and since the switch winding 19 is then included in series with winding F it follows that the increase in value of current traversing winding 19is likewise retarded, with consequent augmentation of the time element of response of switch S Closing operation of switch S is retarded 'in a like manner. Similarly, upon movement of contactor 12 from dotted line position a to the full line rupt the armature and series field circuit connections.

Such full line positioning of contactor 12 likewise results in de-ener 'zing coils 18,

19 and 20 in sequence, w ereby the contacts 22, 23 and 24 are returned to their initially open or field weakening positions. The control elements are thus automatically I reset for the cycle of operation aforede i In practice the contacts of switches S, S and S in Fig. 1 are of the spring closed type, whereas by the arrangement illustrated in Fig. 2 the use of the spring'closed type of con tact is obviated. As aforeindicated, positive commutation of the shunt field resistance in steps is efiected without requiring the use of electrical interlockin relays or contacts.

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

1. In a device for controlling :the shunt field strength of direct current motors, the combination with a shunt field winding and a plurality of resistance sections to be in- 25 cluded in or excluded from the circuit of said winding, of a plurality of electroresponsive switches to control said resistance sections, and means for insuring operation of said switches in a predetermined sequence, said 39 means comprising a member operable by the winding of each of said switches for jointly controlling one of said resistance sections and the energizing circuit of the next succeeding electroresponsive switch, each of said energizing circuits respectively including in series therewith said shunt field winding.

2. In a device for controlling the shunt field strength of direct current motors, the combination with a shunt field winding and 40 a plurality of resistance sections to be included in or excluded from the circuit of said winding, of a plurality of electroresponsive switches to control said resistance sections, said switches each having an inherent time element of response for effecting opening or closing of the contacts thereof, and means for utilizing said time element of response of said switches to insure sequential commutation of said resistance sections with respect to the shunt field winding, said means comprising circuit connections whereby each of said switches upon response thereof is adapted to control one of said resistance sections and the operating coil of the next suctn ceeding switch, certain of said operating coils when energized being connected in series with said shunt field winding.

In witness whereof, I have hereunto subscribed my name.

on EDWIN W. SEEGER.

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