US856540A - Starter for electric motors. - Google Patents

Description

No. 856,540. PATENTED JUNE 11, 1907. W. G. MAYO & J. HOULEHAN.

STARTER FOR ELECTRIC MOTORS.

APPLICATION FILED FEB. 11, 1907.

3 SHEETS-SHEET 1.

W1 TNESSES [ZVVE'N mm I ATTORNEYS PATENTED JUNE 11, 1907.

W. O. MAYO & J. HOULBHAN.

. STARTER FOR ELECTRIC MOTORS.

APPLICATION FILED FEB. 11. 1907.

3 SHEETS-SHEET 2.

J I 2% v O %ZZZ77Z fl/wya I A TTORNE 1 5 No. 856,540. PATENTE'D JUNE 11. 1907. W. o. MAYO & J. HOULEHAN.

STARTER FOR ELECTRIC MOTORS. APPLICATION IILBD FBB.11, 1907.

3 SHEETS-SHEET 3.

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2 rheostat is cut out step-by-step, there will be UNITED STATEgPATENT OFFICE- WILLIAM C. MAYO AND JOHN HOULEHAN, OF EL PASO. TEXAS, ASSIGNORS OF ONE-THIRD TO GEORGEE. BRIGGS, OF EL PASO, TEXAS.

STARTER FOR ELECTRIC MOTORS.

Specification of Letters Patent.

Patented June 11, 1907.

Application filed February 11,1907. Serial No. 356.821.

To all whom, it 71210.;7 concern.-

Be it known that we, WILLIAM C. MAYO and J OHN HOULEHAN, citizens of the United States, residing at El Paso, in the county of El Paso and State of Texas, have. invented a new and useful Starter for Electric Motors, of which the following is a specification.

This-invention has reference to improvements in starters for electric motors and is designed more particularly for starting direct current shunt wound motors, and its 0bject'is to provide a starter which, when the switch is thrown, will automatically and gradually out out the starting rheostat by and inaccordance with variations in line current due to the speeding up of the motor.

To this end, the invention consists essentially in means for putting the rheostat switch arm under stress tending to move it in a direction'to cut out the resistances and providin a release mechanism which will control tie speed of movementof the rheostat arm by and in accordance with the fluctuations of current set up in the circuit by the increasing speed of the motor. Since the a surge of current with eachstep and with each increase in the speed ofthe motor. This surge of current acting on an electro-magnetic device will release the rheostat arm to move under the stress of a spring, and as soon as the equilibrium has again been established between the field and armature circuits the release mechanism will again catch the rheostat arm. The arrangement is such that the current surge will permita movement of the rheostat switch arm across the contacts coincident with the surges and to an extent commensurate therewith.

The invention will be clearly understood from the following detailed description taken in connection with the accompanying drawings forming part of this specification, in whicli,'

Figure 1 is apartially diagrammatic view of'the improved motor starter in the initial position; Fig. 2 is a similar view of the motor starter in the first-position when the rheostat arm is about to move across the rheostat contacts; and Fig. 3'is a side view, partially in section, of the switch mechanism.

Referring to the drawings, there is shown the us al base plate or panel 1, which may be of slate or other insulating material comof sh. nt wornd motor.

monly used for the purpose. Passing through this plate near the bottom is a stud 2 having an annular flange 3 for engaging against the base plate 1 and by means of which, together with a nut 4 screwed on to the stud where it extends throw gh the back of the base plate, the said stud is seci'rely fastened to said base plate, and this nit 4 may confine the terminal of a conductor 5, thus putting said conductor into good electrical connection with the stud. Near the other end of the base plate or panel there'is arranged a series of contact studs 6 having stems, not shown, passing through the base plate and receiving nuts 7 whichconfine the studs 6 to the base plate and also clamp the terminals of the leads 8 coming from the rheostat coils 9, diagrammatically represented in Fi s. 1 and 2 but which will be constructed an located in the 1' s"; al manner back of the panel or base plate 1. The rheostat coils are arranged as usu al in series, and from intermediate points the leads 8 branch off to the contacts 6. One end of the rheostat is connected by a branch conductor 10 to a binding post 11 on the base plate, which binding post 11 is, in turn, connected by a oondr-ctor 12 to one brush 13 of the armature 14 of an ordinary shunt wound motor, the other brush 15 of said armature being connected by a branch conductor 16 to a condvctor 17 coming from a terminal 18 of the power circuit, in which .circrit will, of course, be included the usual main switch, not shown. The other terminal 19 of the power circuit is connected by a conductor 20 to a binding post 21 which, in turn, connects by conductor 22 to a contact stud 23 adjacent to the stud 6 connected to the end of the rheostat, which is coupled by the conductor 10 to the binding post 11. From the conductor 17 comin from the terminal 18 is branched the fie d 24 of the shunt wound motor, which field, as well as the armatr re 14 of the motor is only diagrammatically represented in t e drawings, and this diagrammatic representation is to be understood as indicative of any approved or St itable type The other terminal of the field is connected by a conductor 25 to a binding post 26 on the base plate, and this binding post 26 is connected by condi'ctor 27 to a magnet coil 28, to be hereinafter referred to, and this magnet coil; is connected by a conductor 29 to the end of the rheostat, coils 1o lever.

30 the position shown in 40 out and 50 cut out of circuit.

60 41 is constrained to.

9 remote from the end connected by the conductor 10 to the binding post 11.

Leaving the circt' it connections for the time being, we will now describe'the switch 5 arm mechanism and afterward trace out the circuits and the operation of the switching devices.

Upon the stud 2 is mounted the hub of a lever 31 which may betermed a retaining This hub 30 is cored out at the outer I end and there receives a spring32 and a retaining nut 33 screwed stud, the said nutubeing provided with an annular groove '34 to'receive the end of the r 5 cored out portion of the hub 30. Thehub 30 extends to a point adjacent to the flan e 3 on the stud and is' stepped or reduced indiameter to receive certainparts to be 'hereinafter referred to. One of these artsis-the 2o hub 35 of a switch arm lever 36, t e outer or free end of which is movable across and makes contact with the contact studs 6 before referred to, the said studs being arranged on an arc of which the axis of thestud 2 is i 2 5 thecenter. It will be seen that the hub of the retaining lever 31 has a/journal bearing upon the stud 2, and the spring 32 is so connected to the stud 2 and hub 30 that it will tend to maintainthe retaining lever 31 in I 1 and'will be put under stress when the moved to the position shown in Fig. 2, where it will be maintained by the attraction of the polepieces 37 of the magnet 28, which ole 35 pieces will then engage an armature :b 00k 38 fast onthe lever 31 this magnet constituting an electromagnetic retaining device such as is used in motor-starting switches. The hub receives a spring39fast at one end to the said hub 35 and atithe other end to the hub 30 of the retaining lever 31, this spring being put under stress when the reta' glever 31 is moved to the position 5 shown in Fig. 2 and tendingto carry the switch arm 36 from the position shown" in Fig. 2 over the series of contact studs 6 until it is in position tobridge the contact studs 6 and 23 after the rheostat coils have all-been of the step portions-thereofand adjacent to the hub 35 is a ratchet Wheel 40, and carried" .by the switch arm 36 is a block 41 having a 5 5 stem 42 extendin through brackets 43 projecting from sai switch arm 36, and this block 141 is providedwith ratchet teeth 44 movable into and out of the path of the teethof the ratchet wheel '40. This block move to a position to bring its teeth 44min engagement with the ratchet wheel 'by -a spring 45 surrounding the stem 42 between thebrackets43 and in contact with one of the brackets and a collar :2 46 on said stem. The upper end of the stem on to the end of the retaining lever 31 is 350i the switch arm 36 is also cored the stress of the spring 45, is arrangedto be engaged by the toothed end 48 of a Spring arm 49 carriediby a post ;50 fast on and projectingfrom the base plate or panel 1, and a stop pin 51 limits the movement of the arm 49.. Projecting from the block 4]. is a pin 52 which is located in the path of a cam face 53 formed on a boss 54 integral with or secured to the rear face of the retaining lever 31. The cam face 53 terminates in a hook '55 which, after the cam face 53 has-engaged under the pin 52 and raised the latter against the stress of the spring 45 .out of engagement with the ratchet wheel 40, will engage said pin 52 for a purpose which will hereinafter ap ear.

pon one side of the hub 35 ofthe-switch arm 36 is formed a cam projection 56 in the path of the free end of a lever 57 pivoted to a stud58 rising from the base plate 1. This lever 57 carries a bearing roller 59 on its free end to engage the face ofthe carnh56 and this lever 1S provided with a series of perforations 60 to. receive the end of a spring 61, the other end of which engages an arm 62 pivoted on a stud 63 rising from the base plate 1 adjacent to the ratchet wheel 40. Carried by the arm 62 at a point coincident with its axis upon the pivot pin 63 is an anchor escapement 64 in the path of the teeth of the ratchet wheel 40, and the other or 'free end of the. arm 62 carries an armature 65 in operative relation with the solenoid 66, one terminal of which is connected by the conductor 5 to the stud 2 and the other terminal of which is connected by a conductor 67 with the binding post 21 before referred to. The retaining lever 31 is provided at its outer end with a manipulating handle 68* which may be of insulating material and is arranged to make contact with a contact stud 69 rising from the base plate 1 adjacent to the contact stud 23 and magnet 28, and this stud 69 is connected by a conductor 70 to the conductorv29 before referred to.

. Let it now be assumed that the retaining lever 31 is in the off position, that is, in the position shown "in Fig. 1, overlyin the switch arm 36, The service switch is c osed but as yet no current will flow to the motor. The operator now takes hold of the knob or handle 68 and moves the retaining lever 31 to the right, as viewed in Fig. 1, to the position shown in Fig. 2, that is, until the armature 38 is in'contactjwith-the poles 37 of the ma net 28.and the retaining lever 31 has to the binding post 26, thence by conductor motor field 24, conductor 25 .27 throu h the magnet 28, energizing the latter and locking the retaining lever .31 in the position shown in Fig. \2. From the magnet spool 28 the current will pass by conductor 29 to branch conductor 70, thence to the retaining lever, 31, to the stud 2, thence by way of conductor to the solenoid spool 66, thence by conductor 67 to the binding post 21, and'by conductor to the other terminal 19 of the power circuit. When the retaining lever 31 was moved to the right as viewed in Figs. 1 and 2, thesprings 3'2 and 39 were'put/ under tension. When the re taining lever 31 overlaid the switch lever 36 prior to the movement 'ust described, the cam face 53 had raised t e block 41 by engagement with the pin 52 until the end 47 of the stem 42 had been engagedby the catch end 48 of the arm 49. However, when the lever'31 had been moved, as 'ust -described,

to the right in Figs. 1 and 2, t e cam face 53 was removed from engagement with the pin 51 and the teeth 44 on theblock 41 weremoved by the spring 45.into engagement with the teeth of the ratchet whee 40, thus releasing the end 47 of the stem 42 from engagement withthe hooked end 48 of the arm 49. In this osition of the parts the switch arm 36 is lot: ed to the ratchet wheel and at the same time the ratchet wheel 40 is locked from movement by the engagement therewith of one of the teethof the anchor escapement 64 before mentioned, and in this position of the arts the, roller 59 of the lever 57 rests upon t e highest point of the cam 56 carried by thehub 35 ofthe switch arm 36,

' so that the-arm 62 carr ing the solenoid armature Q1 core 65-is hel in a position to carry the solenoid core '65 from out the saidsolenoid the 'stress of the spring 61 with a force due in part to the upward position .of the lever 57 when en agedby the highest part of the cam 56. tjwill also be evident that when the retaining lever; 31 was moved to the osition shown in Fig. 2 .the current coming in at 18 divides at the -'unction of the ,conductor 16 with the con uctor 17 and the greater portion flows throu h the brush 15, armature 14, the brush 13, 51c conductor 12, binding post 11, conductor 10, all of the resistance coils 9 in series, thence by conductor 29 and unitin at theconductor with the current that as passed through thefield. The relative resistance of the retaining ma net coil 28 and the resistance coils 9 is so adjusted that the ma'or portion of the currentwill pass through t 4 e armature, and. the field under these conditions will. be but weakly energized.

In considering the'further operation of the starting device, it will be assumed that the starting current flowing through the armathrough thesolenoid 66, which latter, however, is adjusted to overcome the spring 61 with a current but little in excess of the fullload current. The result is that the core 65 will be pulled down into the solenoid against the action of the spring 61 and the upper tootlrof the anchor escapement will be pu ed out from engagement with the teeth of the ratchet wheel 40 while the lower tooth will be moved into engagement therewith, the partsvbeing so adjusted that a slight forward movement of the ratchet wheel has been permitted, after .the manner of an ordinary anchor escapement. The motor having. received current, it will start and begin to rotate and will develop a certain counter electromotive force which will oppose the line current until only su'iiicient current will flow through the motor to maintain its load at the speed already attained. This will weaken the ull of the solenoid and the spring will lift t e core 65 against the pull of tlie'solenoid which will rock the anchor esca ement 64 so that its up er tooth is again in t e ath of the teeth of t e ratchet wheel 40 an the latterhas been permitted to turn a distance of one tooth, thus bringing the arm 36 into engagement with the first active contact stud 6 to out out the first of the-series of re- 'sistance coils 9. This movement of the switch lever 36 is causedby the tension of the spring. 39, as before explained. a The speedof the motor has in the meant-ime'not increased, and, consequently, there is a surge of current due to the cutting out of the first of theser-ies of resistance coils 9, hence the solenoid is again strengthened and the anchor escapeinent 64 is rocked on its pivot against the action of the spring 61 and, on

the :increased counter electromotive' force developedby the increased s eed of the motor, the solenoid is again wea ened as before and the ratchet wheel 40 is released to move a distance ofone tooth and theswitch arm 36 moves to the second contact. This action is repeated again and again until the switch arm 36 has reached the last'of the contact .studs'6 in its path where all the resistance coils are out out and the switch armbridges- .the last contact 6 and the contact stud 23 in direct communication through the conductor 22, binding )ost 21 and conductor 20 with the termin-ai 1.9 of the power circuit, at which time the-motor is su osed' to be running' at full speed under full oad.

As the motor approaches full speed the current taken from the power circuit correspondingly decreases from the fifty per cent. overload to normal "load and the'pull of the solenoid 66 is, therefore,- progressively lessened as the motor speeds up. For this reasonflthe pull of'the'spring 61 is correspondingly lessened automatically-by the action of the cam 56 upon the lever 57 since this is so arranged as to move with the switch arm 36 and allow the free end of the lever 57 to progressively ap roach the arm 62 and thereby lessen the pull of the spring 61 so as to compensate for the lessened pull of the solenoid 66." When the switch lever 36 makes contact with the stud 23 and the contact stud6 adjacent thereto it will be observed that the solenoid 66 is shunted by the two arms 3136 and the current flowing from binding post 26 through the magnet 28 and by way of conductor 70 to the contact stud 69 will flow by way of the retaining lever arm 31 to the switch arm 36, thence by contact stud 23, conductor 22, binding post 21 and conductor 20 to the terminal 19 of the power circuit, and the armature circuit coming by conductor 12 to the binding post 11 is completed through the conductor 10 to contact 6, thence through the switch arm 36 to the contact 23, and from thence, as before, to the power circuit terminal 19.

It will be seen that the operation of the starting devices is entirely automatic and that the movement of the switch arm 36'to cut out the resistances is strictly in accordance with the increasing speed of the motor; thus all danger to the motor from a heavy starting current, such as might occur from a too rapidmovement of the switch arm to cut out the resistances when operated manually by a careless operator is entirely -avoided.

Now, let it be assumed that it is desired to stop the motor. The main switch is open. Immediately the magnet 28 is deenergized and the spring 32, acting upon the retaining lever 31 will carry the same toward the left in Fig. 2, and, finally, to the position shown in Fig. 1. As the retaining lever 31 moves toward the left the cam face 53 will engage the pin 52 on the block 41 and lift the teeth 44 out of engagement with the teeth of the ratchet wheel 40, and the hook end 55 will ultimately engage the pin 52 and those parts constituting the connection between the lever arm 31 and the switch arm 36 will cause the said lever 31 to carry the switch arm 36 to the left, as viewed in Figs. 1 and 2, until a stoppin 71 is engaged by said'arms and their further movement to the left thereby stopped. At this point the beveled end 47 of the stem 42 of the block 41 is engaged under the hooked end 48 of. the arm 49 and the switch arm 36 is thereby prevented from movement toward the right when, as has been heretofore explained, the lever 31 is moved to the right to again set the motor in operation.

When the switch arm 36 is in the extreme left or off position its outer end may conveniently make contactwith an idle contact stud 72, indicated by dotted lines.

The magnetic circuit of the solenoid 66 is preferably a double one with practically one air gap, the other bein very slight. The solenoid may be ironclad with two poles and the armature or core may be aplunger workchanges since, if it worked too near the saturation point, it might not respond tproperly should the spring-get a little out o adjustment. While the lack of sensitiveness would be most apparent when the motor was nearly up to normal speed, it is well to provide against such. a contingency and if such a solenoid as just described 1s used the lack of sensitiveness will not occur.

Of course the field current always passes through the solenoid while the latter is in operation, but as this current is a constant factor, it has no bearing on the operation of the solenoid which need only be properly designed to take care of it.

' When the switch arm 36 has reached the contact 23 the teeth of the block or dog 41 will be lifted out of engagement with the ratchet wheel 40 by the cam face 53.

e claim 1-. In a motor starter, a propelling means for the starting switch having a constant I tendency to move it across the steps of the startin resistance in succession, and means controlled by the variation of current strength due to the' cutting out of the successive groups of resistances of the starter for controlling the movement of the starting switch across the terminals of the resistances.

2. In a motor starter, a propelling means for the starting switch having a constant tendency to move it across the steps of the starting resistance in succession, a detent controlling the movement of the switch arm, and an elect-roanagnetic controlling device for the detent sensitive to variations in the starting current to permit a movement of the switch arm'in accordance with said variations of the starting current.

coils, a switch arm engaging the terminals of said coils, another arm connected to the switch arm by a spring connection, means for holding said arm in a-position to put the spring connection under stress, an escapement for controlling the movement of the switch arm, and an electro-magnetic control for said escapement sensitive to variations in the starting current.

4. In a motor starter, a series of resistance coils, a switch arm arranged to engage the terminals of said. coils, another arm having a spring connection with the switch arm and movable to put the spring connection under stress, a ratchet wheel mounted upon the axis of the switch arm, a toothed lock or pawl connecting said switch arm to said ratchet wheel, a detent for said ratchet wheel, and an electro-inagnetic actuating device for said [IO 3. In a motor starter, a series of resistancea ances, a switch arm arranged to make contact in succession with the terminals of said resistances, another arm, a spring connection between the two arms put under stress by the movement of the said other arm, a-

ratchet wheel having its axis of rotation incident withthe axis ot the switch arm, a spring-actuated pawl movable into and out of engagement with the ratchet wheel, a

. fixed detent for engaging the a'wl when out of engagement with the rate et wheel and for then holding the switch arm from movement under thestress of the'spring, an escapement for the ratchet Wheel, and an electro-magnetic controlling device for the escapement sensitive to variations in the startmg current.

6. In a motor starter, a series of res stances, a switch arm movable over the termi nals ofsaid resistances in succession, another arm, a spring connection therefrom to the switch arm, a ratchet wheel mounted 011 the axis of the switch arm, a pawl on the switch arm engaging the ratchet wheel, a

, gagement spring-retained detent for the ratchet wheel, an electro-magnetic controlling mechanism for the detent sensitive to variations in the starting current, and means for varying the tension of the spring connected with the de tent in direct ratio to the power of the de tent o crating mechanism.

7. n a motor starter, a series. of resistances, a switch arm movable in succession over the resistance terminals another arm, a spring connection therefrdinto the switch arm, a ratchet wheel mounted to turn upon the same axis as the switch arm, a spring-actuated pawl connection between the switcharm and the ratchet wheel, a cam upon the other arm engaging said spring-actuated pawl'to move it out of engagement with the ratchet wheel, a detent for the ratchet wheel,

and electro-magnetic controlling. means'for" thedetent sensitive to variations in the startmg current. I

8. In a motor starter, a series of resistances, aswitch arm movable over the'resistance terminals in succession, a ratchet wheel mounted to turn upon the same axis as the switch arm, a spring-actuated toothed pawl on the switch arm for engaging the teeth of the ratchet wheel, a fixed detent in the ath of said pawl for holding the latter out 0 enwith the ratchet wheel and at the same time holding the switch arm against movement, another arm mounted upon the same axis as the switch arm, a cam upon said tension thereby, one of saic arm for o erating said pawl, a detent for said ratchet w eel, electro-magnetic means sensitive to variations in the startingcurrent for controlling said detent, a spring acting on said detent in opposition to the electro-magnetic controlling means, a lever carrying said spring, and a cam movable with sai switch arm and controlling said lever to vary the pull of the spring attached to the detent. 9. In a motor starter for shunt wound motors, a series of resistances included in the ar mature circuit of the motor, a switch arm for successively cutting out said resistances, electro-magnetic means sensitive to variations in the starting current for controlling the movement of the switch arm step by step and included in the motor circuit when the resistances are included therein,- and means for shunting said electro-magnetic controlling devices when the resistances are cut out of the motor circuit.

10. In a motor starter, a series of resist ances, a switch arm arranged for successive engagement with the terminals of said resistances, another arm, s rings put under i springs connecting the two arms, an electro-magnetic retaining device for the la'st-named arm included in the motor circuit, electro-magnetically controlled means sensitive to variations in the power circuit for permittin the switch arm to move under the stress 0 the sprin a coupling mechanism connecting the switch controlled means, and means carried-by the other arm for uncouplin the said switch arm and returning it to t e initial position.

11. In a motor starter, a series of resistance coils, a spring-actuated switch-arm movable across the terminals of the resistance coils in succession under the action of the sprin a detent for controlling the movement of t e switch-arm, and an e ectro-magnetic controlling device'for the detent sensi-. tive to variations in the starting current to arm to the said electro-magnetically permit the movement. of the switch-arm under the impulse of its s ring inac'cordance with said variations of t e starting current. In testimony that we claim the foregoing as our own, we have hereto afiixed oursignatures in the presence of two witnesses.

WILLIAM C. MAYO. JOHN HOULEHAN.

Witnesses to signature of William C. Mayo:

W. A. WARNOCK, Mrs. M, L. DUNHAM.

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