US654410A - Apparatus for controlling electric motors. - Google Patents

Description

No. 654,410. v Patented I kuly 241 |900. F. A. MEHRlCK @L E. w. STULL. APPARATUS FR C-NTHLLING ELECTRIC MOTORS.

(Application med Nov. 22, 1899.)

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Patentd July 24, |900. F. A. MEHRICK & E. W. STULL.

APPARATUS FUR GUNTROLLING ELECTRIC MOTORS.

(Appxicmon mea Nov. 22, 1599.)

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No. 654,4m, y .Patented my 24, |900.

F. A. MEnmcKe. E. w. -sTuLL. APPARATUS FOR CUNTBOLLING'ELEGTRIC MUTURS.

(Application led Nov. 22, 1899.)

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NITE STATES PATENT ence.

FRANK -AIMERRICK'AN'D r`EMimErr w. STULL, or JoriNsTowN; rENNsYLvA-Y NIA, AssIcNons To THE LonArN STEEL coMPANv, or PENNSYLVANIA.

APPAnx-irosl FoacoNTRoLL-ING.ELECTRIC MOTORS.

srEcrnrcATroN'ferrnng part of Letters Patent No. 654,410, dated Jury 24, leoo.

' `Application liled November 22, 1899. Serial NO- 737|8'79 (N0 modld Be it known that we, FRANK A. MERRIC'K and EMMETT W. STULL, of Johnstown, in the county of Cam bria and State of Pennsylvania,

have invented a new and useful Improvement in Apparatus for the Control of Electric Motors, of which the following isa full, clear, and exact description, reference being had to the accompanying drawings, which forni a ro part of this specification. U

Our invention has relation to apparatus for the control of electric motors, and is more particularly designed for use on electric-railway cars which are propelled by four motors,

although in part it is equally applicable in connection with two motors.

One object of our invention is to provide apparatus by which a plurality of electric motors may be started from a position of rest in zo which all their'elements are connected in series and changed over to a multiple position in whichv pairs of the motors are connected in multiple and the multiple pairs in series with each other through a series of intermediate circuit changes of suitable character to accelerate the motors without injury to their coils or brushes. By ha'ndlingthe motors in this manner we are -able to get a maximum effect of torque, particularlyin starting from 3o a position of rest. We also make it possible to use a higher potential on the line with less drop in potential along the line.

A further object of our invention is to provide a brake-controlling switch of novel char' acter for connecting the motors in a closed circuit independent oi' theline and in a manner whereby their braking action when running as generators driven by the momentum of the car may be effectively utilized; also,

4o to provide means whereby said switch cannot be operated until the motors have been disconnected from the line-circuit, thereby preventing injury to the motors by reason of any movement of the brakefswitch tending to cause them to act as generators while they are still receiving'current from the line; also,

to provide means whereby the motors cannot be connected with the line except when the brake-switch is at the olf position, so that 5o as long as the motors are connected to run as generators no current can be made to pass to them from the line. v y

Other minor objects of the invention will hereinafter appear. y

With these objects in View the invention consists iirst in the combination, with four electric motors, of a pair of controller-drums intergeared one with the other, so that they may be simultaneously operated by the movem ent of a simple handle-lever, each drum hav- 6o ing contacts and connections for changing from series to parallel one pair of the motors through a series of intermediate steps in which the strength of the fields and the ohmic re,- sistanceof the circuits are gradually changed to gradually accelerate the motors, the two drums being electrically connected in series.

Our invention further consists in a brakecontrolling switch having contacts, brushes, and proper electrical connections whereby 7o the motors may be connected to operate as generators and the ohmic resistance of the motor-generator circuit may be reduced as the speed of the armatures decreases; also, in the provision of contacts carried by the brakecontrolling switch and controlling the passage of current from line to the motors; also, in the provision of an electromagnetic locking device for the brake-switch, whereby it cannot be operated until the current is cut 8o off from the motors.

In connection with the apparatus we employ artificial resistance for the rheostatic control of the motors in starting from a position of rest and for using in the braking-circuit. Ve also employ a combined reversing and cut-out switch having certain novel features hereinafter pointed out.

Referring to the accompanying drawings, Figure 1 is a diagram which shows the va- 9o rious apparatus and connections for a'fourmotor equipment. Fig. 2 is' a detail view showing the mechanical connection between the two controller-drums. Fig. 3 is a detail View showing the lock for the brake-controller. Fig. 4 is a horizontal section through the brake-controller. Fig. 5 is a diagram showing conventionally the several positions of the motors for the respective indicated or notch positions of thecontroller-drums. Fig. roo

6 is a similar View showing the several positions or circuit positions effected by the operation of the brake-controlling switch.

In the diagrams Figs. 1, 4, and 5, A A2 A3 A'l designate the respective armatures of four electric motors, (designated as 1, 2, 3, and 4,) and F F2 Fi Fl the respective fieldcoils of the same.

C C2 designate two controller-dru ms shown in developmentand each of which is provided with a plurality of contacts c/ or c2, arranged upon rotation of the drum to be engaged by contact brushes orV fingers b b2, dce. Drum C/ controls motors 1 and 3, while the drum C2 controls the motors 2 and 4. These drums are mechanically of the well-known cylinder type and need not be further described. The arrangement of cont-acts on each drum is in accordance with the system and apparatus for controlling motors described and claimedA in the applications of F. A. Merrick, Serial Nos. 713,690 and 726,928, filed April 4, 1899, and August 11, 1899, respectively*that is to say, each drum has contacts so arranged as to change two motors from series to parallel relation through a series of intermediate relations in which artificial resistance in series with the motors is first gradually removed from circuit as their counter electromotive force increases, then the fields are connected in multiple with the armatures in series, then the armatures are connected in multiple and the iields in series, and iinally the two motors as a whole are connected in multiple. The two drums are duplicates of each other, except that the upper group on the drum C2 are grounded on shaft,while the drum C' is provided with a continuous contact o d for the upper brush b', to which is connected the conductor C D, which connects the two drums electrically in series.

g g/ g2 are intermeshing gear-wheels which connect the shaft of the two drums, and D is the operating handle or lever.

R S represent the reversing and cut-out switch, which is also in general of a wellknown type, with a plurality of contacts S and brushes b s for engagement therewith. This switch has seven different positions, indicated by the dotted vertical lines and marked, respectively, 2 t 4 back, 2 da 4 ahead, A ahead, off, baclg 1 and 3 back,77 H1 and 3 ahead.

The conductor C D is connected to the brush 1227 of the controller C2, and this brush is connected to a contact s4, which is grounded on the shaft of the reversing and cut-out switch. This connection provides an immediate ground connection for motors 1 and 3 when the reversing and cut-out switch is set in position to run these two motors either forward or backward.

RB', HB2, RBS, and RB*l designate, respectively, four resistance-boxes or rheostats arranged in two pairs, whose individuals are electrically connected in each pair and having their elements or resistance units arranged and connected so that portions of the resistance of each box may be successively cut into and out of circuit by the action of the controller-drums C C2 and also by the action of the brake -controlling switch presently described, each of said drums controlling the relation to circuit of one pair of the boxes.

We do not deem it necessary to describe in detail the grouping and arrangement of t-he various contacts or to specifically point out the various electrical connections, as they are best seen and understood by reference to the drawings, and our invention is not limited thereto. Nor will it be necessary to trace out the path of the circuit in the several different positions of the drums C' C2, as this is graphically shown in Fig. 5. By the lettering on the drawings indicating the connections of the various leads and conductors this maybe readily done. Referring to Fig. it will be seen thatin the first position ofthe said drums all the elements of all four motors are connected in series, the artificial resistance being also in series with the motors, the current passing through the armatures and field-coils of motors Nos. 1 and 3, thence through one pair of the resistance-boxes RB HB2, and thence through the other two motors and the other pair of resistance-boxes to ground. At position No. 2 a part of the resistance is removed from circuit, and at position No. 3 still more is removed. At position No. 4 the entire resistance is removed, the motors still remaining all in series. At position No. 5 the fieldcoils of each pair of motors are connected in multiple. The circuit is then momentarily opened and the armatures of each pair of motors are connected in multiple with the fields in series. This is shown at position No. G. In position No. 7, which is the final position, each pair of motors are connected in full multiple. In passing from position 4 to position 5 the field-coils of one motor of each pair are temporarily removed from circuit, and in passing from position 6 to position 7 the circuit is momentarily broken through the armature of one motor of each pair, and then through the field-coils of the same, preparatory to passing to full multiple connection of each pair. These, however, are not indicated or notch positions of the controller and are not shown in the diagram Fig. 5. Throughout all these circuit changes the two pairs of motors remain connected in series. It will be readily seen that in this way we are able to get the maximum effect of torque in starting the motors, which is important where the load is heavy. This method of control also enables a higher potential to be used on the line with a much less sudden drop in potential.

We will now proceed to describe our iniproved brake-controlling switch, (shown at BCS in Fig. 1.) This switch consists of a rotary drum similar mechanically to the oontroller-drums and carrying upon its periphery a plurality of contacts which we have marked IOO Z Z' and z c, duc., to Z22. These contacts are arranged in seven electricallydisconnected groups. Contacts Z Z constitute one group, contacts z c" z2 z3 e4 z5 the second group, contacts ZG and ,e7 the third group, contacts z2 zg @'10 e the fourth group, contacts cl2 to e, inclusive, the fifth group, contacts als and cl2 the sixth group, and contacts z2() to .222, inclusive, the seventh group. It will be noted that in the arrangement of contacts groups 2 and 5, 3 and 6, and 4 and 7 are respectively duplicates. It Will also be noted that if a vertical central line be drawn through the said groups a similar arrangement of contacts is found, with the exception of the first group upon each side of said line with an open space between them. For engagement with these contacts two opposite sets of brushes or tingers are provided, those at one side being marked P p p p2, &c., to p44, and those at the opposite side R r r' r2, the., to rs. These two sets of brushes are designed to engage, respectively, the duplicated contacts at the two sides of the drum, there being, however, two less brushes of the r group than of the p group. The drum has fourpositions in which the brushes 1^ to r and p to p9 engage the contacts of the second, third, fourth, fifth, sixth, and seventh groups, and another or off position in which the brushes P and R engage the contacts Z Z,the other brushes being out of contact. Boe indicates a blowout coil for the said drum, and L C a lockinagnet-coil having an armature K, (see Fig. 3,) carrying a pawl K5, arranged to engage a tooth K2 on the shaft of the brake-controller drum. K2 is a spring for retracting the said armature when it is released by the magnet. Thebrush R is connected to the trolley or high-potential side of the line through the usual car Wiring and instruments, as shown, and the brush P is connected to the lbottom brush of the controller-drum C through the magnet-coil L C, as shown. The circuit from the trolley to the controllers C' C2 and the motors must therefore pass through the brush R, contacts Z Z', and coil L C. Therefore no current can pass to the motors except the brake-controller is in its off position, and so long as the current is passing to the motors the coil L C is energized and keeps the armature-pawl K' in engagement withl the tooth K2. The brake-controller is thereby locked and cannot be operated until the current is cut off from the motors. Brush p is connected to the negative side of the armature A4 and brush p11 to the positive side of the same. Brushes p, p2, and p2 are connected to tWo of the resistance-boxes. Brush p2 is connected to the negativev side of the fieldcoil F and brush p4 to the positive side of the same. Brush p5 is connected to the positive side of armature A3 and brush p6 to the negative side of the same. Brush p7 is connected to ground. Brush p9 is connected to the negative side of the field-coils F2 and brush p40 to the positive side of the same.

Brush r is connected to the negative side of armature A2 and brush r2 to the ositive side of the same. Brushes r r6 are connected to the resistance, brush r2 to the negative side of field-coils F2, and brush r2 to the positive side of the same, brush r4 to the positive side of armature A', and brush T5 to the negative side of the same. Brush T7 is connected to the negative side of field-coils F4, and brush r2 to the positive side of the same through the blow-out coil B00. The various connections are made by means of branches to the main leads. When the drum is moved to the iirst position indicated by the dotted vertical lines l, the circuit from line to the motors is broken and the path of the current may be traced as follows: from the positive brushes of the armatures A2 and A4 in multiple to the brushes r9 p41, contacts 522 .222, brush p40, field-coils F2 to brush 9, contacts 518549, brush frs, field-coils F4, resistance-boxes R132 HB4 to brush p7, contacts @44 .242 542. The path of the current is here divided, the contact ,212 being connected to the negative brush of the armature A through brush 15, while the contact Z13 is connected to the negative brush of the armature A3 through the brush p6. The current from the positive brushes of the said armatures meets in the contacts of the fourth group through the brushes r4 p5 and, uniting, passes to field F by brush p4, returning to contact z, thence by contact .c7 and brush r2 to the field-coil F2, thence through resistance RB R132, thence to brush fr', thence to contacts z z', and to the negative brushes of the respective armatures A2 A4.

It will be seen that the motors are connected in circuit relation similar to positions 6 of t-he controllers C C2, eXceptthat the resistance is in circuit and the armature connections are reversed. In position 2 brush p7 loses its connection With contact 218 and instead brush r6 engages the contact 215. Brush p also loses engagement with contact a2 and brush r' engages contact z2. The effect of these changes, it will be readily seen, is to out out portions, respectively, of the resistances RB BB3 by shortcircuiting them. In position No. 3 the brushes r6 and r' become disengaged from the respective contacts c45 and e2 and instead brushes p8 and p2 engage, respectively, the contacts zw and a4. This shortcircuits still more of the resistance. In position No. 4 brushes p8 and 192 lose their respective engagements and brushes r2 and ri' engage, respectively, the contacts z5 and 547. This, it will be seen, short-circuits the entire resistance by providing a direct return path to the brake-controller from the negative sides of fields F and F4. The connection of the motors remains unchanged in positions 2, 3, and 4.

By placing the armatures in multiple and the fields in series while the motors are running as generators We are enabled to keep up the strength of the fields as the speed of the armatures decreases, so that combined with IOO IIO

4 static the decrease in the ohmic resistance of the motor-generator circuit by gradually removing the artificial resistance a nearly-constant and properly-regulated braking action results, the potential of the current generated being nearly the same as that at which the motors run when connected with the line-circuit.

By the described arrangement of the contacts with duplicate brushes we provide a Very compact construction of switch. The contacts of the fourth and seventh groups effeet the multiple connection of the armatures and their connection with the fields, the contaets of the third and sixth groups effect the ser-ies connection of the fields, and the contacts of the second and seventh `groups control the resistance.

This switch, it will be seen, may be readily adapted for use in connection with a single pair of motors by omitting one group of each of the duplicate groups and is applicable also for use in connection with various types and constructions of the motor-controllers.

It is obvious that the particular construction and arrangement which we have herein shown and described may be varied without departing from our invention as ,hereinafter claimed. Hence we do not wish to be limited to nonessential and unimportant details.

Having thus described our invention, what we claim, and desire to secure by Letters Patent, is

l. The combination with four electric m0- tors, of two controller-drums, each of which has contacts and connections for changing one pair of said motors from series to parallel, said drums being electrically connected in series with each other.

2. The combination with four electric motors, of two controller-drums, each of which has contacts and connections for changing one pair of said motors from series to parallel, said drums being electrically connected in series with each other, and gear connections' between the shafts of said drums whereby they may be operated in unison.

3. The combination with four electric motors, of two controller-drums electrically connected in series, one with the other, and mechanically intergeared to rotate in unison, each of said drums having contacts and eennections for connecting two motors in series, with either element of one motor in series with the corresponding element of the other motor, and the other elements in multiple, or with the two motors as a whole in parallel.

4. The combination with four electric motors, of two controller-drums mechanically connected to rotate in unison, and each having contacts', whereby two of the motors may be connected in series, or with their armatures in series and their fields in parallel, or with their fields in series and their armatures in parallel, or in parallel as a whole, and means for maintaining a series connection between the said drums in all positions thereof.

5. The combination with a plurality of elecAl tric motors, and a controller therefor, of a brake controlling switch having contacts which control the connection of the motors and the said controller to line and which break such connection when the brale-controlling switch is moved from its ol'f position.

6. The combination with a plurality of electric motors, of abrake-controlling switch, and an electro magnetic locking device for said switch in circuit with the motors, whereby said switch can be actuated only when the motors are disconnected from line.

7. The combination with a plurality of electric motors, of a brakecontrolling switch therefor, a magnet-coil in circuit with the motors, an armature having a pawl for locking engagement with the shaft of said switch, whereby the latter is released only when the circuit through the motors is broken.

8. The combination with a plurality of electric motors,of a brake-controlling switch connected with the motor-circuit, contacts on said switch which control the connection of the motors with the line-circuit and which break such connection when the switch is moved from its off positions, a magnet-coil also in the motor-circuit, and an armaturepawl controlled by said coil engaging the shaft of said switch, whereby the latter is released only when the circuit through the motors is broken.

0. The combination with four electric motors, and a pair of controller-drums for connecting said motors and their elements in different circuit relations, of a combined revers ing and cut-out switch alsol in circuit with said motors, said switch having a grounded contact and means for establishing a direct connection between said contact and two of the motors in certain positions of said switch.

10. The combination with a plurality of electricmotors, of an electric brake-controlling switch having contacts and connections whereby the motors may be placed in a closed circuit independently of line, with their armatures in multiple and their fields in series, and their armature connections reversed.

1l. The combination with four electric motors, and artificial resistance for connection in circuit therewith, of a switch for connecting said motors in a closed circuit to run as generators, and having contacts and connections whereby the motors may be series connected in two pairs with the armatures of each pair in multiple and their fields in series, and other contacts for connect-ing in circuit more or less of the said resistance.

12. The combination with a plurality of electric motors, controlling-switch therefor, consisting of a rotating drum having therein duplicate sets of contaets,a set of brushes or fingers for each set of contacts, and the necessary electrical connections whereby as said drum is rotated, the motors are connected in a local circuit, to run as generators, part of IOO the said circuit being effected through one set of contacts and ingers and another part through the other set of contacts and ngers.

13. A brake-controlling switch for four motors having fixed contact fingers or brushes, and a rotary drum having two duplicate groups of contacts, each of which groups is arranged to connect the field-coils of one pair of motors in series,two other duplicate groups, each of which is arranged to connect the armatures of one pair of said motors in multiple to run as generators, and two other duplicate groups to insert in and remove from the circuit an artificial resistance.

14. A brake-controlling switch for four motors having fixed contact fingers or brushes, and a rotary drum having two duplicate groups of contacts, each of which groups is arranged to connect the field-coils of one pair of motors in series,two other duplicate groups, each of which is arranged to connect the armatures of one pair of said motors in multiple to run as generators, and two other duplicate groups to insert in and remove from the circuit au artificial resistance, said groups being also divided into two duplicate sets, and the said brushes being arranged in two different sets, one set for each set of contacts.

l5. A brake-controlling switch for four moik tors having liXed contact fingers or brushes,

and a rotary drum having two duplicate groups of contacts, each of which groups is arranged to connect the eld-coils ot' one pair of motors in series, two other duplicate groups each of which is arranged to connect the armatures of one pair of said motors in multiple to run as generators, and two other duplicate groups to insert in and remove from the circuit an artificial resistance, and other contacts for connecting the motors in circuit with the line when the switch is in oftl position.

In testimony whereof we have axed our signatures in presence of two witnesses.

FRANK A. MERRICKI, EMMETT W. S'IULLA Witnesses:

MYRTLE E. SHARPE, ANNIE M. Mosns.

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