US1447477A - Electrical starter for explosive engines - Google Patents

Description

Mar. 6, 1923. 1,447,477. (5. K. KNAPP.

ELECTRICAL STARTER FOR EXPLOSIVE ENGINES. I

FILED 007.11.1920. 4 SHEETS-SHEET 1.

illlnnlllllllllm Mar. 6, 1923. 1,447,477. G. K. KNAPP. ELECTRICAL STARTER FOR EXPLOSIVE ENGINES.

FILED OCT. I l, 1920. 4 SHEETSSHEET 2:

Mar. 6, 1923. 1,447,477.

a. K. KNAPP.

ELECTRICAL STARTER FOR EXPLOSIVE ENGINES.

FILED 0CT.I1,1920. 4 SHEETSSHEET 3.

Mar. 6, 1923. 7 1,447,477.

G. K. KNAPP.

ELECTRICAL STARTER FOR EXPLOSIVE ENGlNES.

FILED OCTJI. 1920- 4 SHEETSSHEET 4- iatentcci li/lar. 6, 1923.

UNITED STATES GEORG KARL KNAPP, 0F NUREMBERG, GERMANY.

ELECTRICAL STARTER FOR EXPLOSIVE ENG-IITIES.

Application filed October 11, 1920. Serial No. 416,284.

To (W iii/mm. it may concern:

iie it l-rz'iown that l. ti'nono Kain. Exam. a citizen of Germany. residing at Nuremberg. Germany, have invented certain new and useful Improvements in Electrical Starters l'or Explosive Engines; and I do hereby declare, the following to be a full, clear, and exact description of the invention. such as will enable others skilled in the art to which it appei'tains to make and use the inwution relates to improvements in eicc'ti ical starters for explosive engines. and more pai'tieiil.:n'l. v in starters comprising a n'1 ot 'n.'- lyinin'io havi .5 two armature windi "s one of low resistance and few turns and the other one of a greater number of turns and higher resistance. One of the objects of the imprmements is to provide a starter-of this type which when operated as a motor for starting the engine is adapted to pro duce a high torque at comparatively low speed, a id which when operating under no load does not run at excessive speed. \Vith this and other objects in view my invention consists in the matters to be described hereinafter and particularly pointed out in the appended claims. For the purpose of explaining the invention several examples embodying the same have been shown in the accoi'n 'ianying drawings. in which the same letters of retcrcnce have been used in all the "."iews to indicate correspondin parts. In said drawings l, is a plan view (it an explosive engine and a starter disposed on an automobile,

l ig. 2. a diagramniatical View illustratinn the circuits of the starter,

Figs. 3 and 4. show a modification of the system, Fig. 3 showing the same when operating as a motor and Fig. 4 when operating as a generator, and

Fig. 5. a diagrammatical View showing the windii '11" disposed on field poles.

As appc.. c. more particularly from Fig. my improved system consists of an eX i n ('1. imiter-dynamo (Z conthe crank shaft of the engine a suitaliile gearing 0, and a secondary iattr-iry 0. its shown. the whole system is in :ntcd on an automobile ln the prei erred iorizi the gearing (7 is in the torm a change speed gearing. and good results have been obtained by providing a frictional change speed gearing or a gearing of the epicyclic type.

The electrical part of the system. consists of a single armature having two armature windings and f shown separately in the figure. for convenience of illustration. the armature winding 7' being of low resistance and tew turns to produce a large torque when the machine is used as a motor to start the engine and the winding 7' having a high resistance and a greater number of turns for supplying the necessary voltage to charge the battery 0. The motor-dynamo is provided with two field windings Z and p, the winding being of low resistance and tew turns and the winding 7) of higher resistance and many turns. It the system operates as a motor for starting the engine a. switch 73 is set in the position shown in dotted lines, and the current taken from the terminal of the storage battery 6 passes over a lead the motor winding a lead 71 the switch 2', a lead k, the series winding Z, to the ground or frame work of the engine indicated by the minus Sign, and back to the minus terminal of the secondary battery. Furthermore the generator winding 7 is closed over a lead m, a resistance '11, a lead 0, the field windin 7? connected in this case in series, and a lead Therefore. the motor field is excited by both field windings Z and 1), so that a strong torque is produced. In

zuldition the generator winding 7 and its circuit have a braking action resulting in a reduction of the velocity of the armature, whichv is important because for starting the engine a low speed is required. Furthermore the counter-electromotive force within the motor winding is small and the current flowing through the same is large, which, results in a strong torque. The torque is at its maximum at the beginning of the starting operation and when the power required for starting the engine is high. As the velocity of the motor increases the current produced in the armature winding 7" and energizing the field winding 72 gradually causes an increase of the strength of the field. Therefore the velocity of the system is not increased upon a reduction of the load to such an extent as in the case of a pure series motor, the system having in a certain degree a character sin'iilar to that of. a compound motor which upon a reduction of the load assumes more and more the character of shunt wound motor. Furthermore by increasing the intensity of the field by means of the winding 7) the torque is increased. Experiments have shown that practically this increase amounts to as much as from 20 to though the current supplied by the storage battery is not increased.

lit will be understood that the current flowing through the winding f and resulting in an increase of the intensity of the field depends on the value of the resistance H. H the resistance is high, for example 30 ohms, the current flowing; through the field winding 77 varies in practical constructions according to the number of revolutions from U) to 1.5 amperes. As the number of the turns of the coil 77 high the field is con siderably increased, as has been shown by experiments. ltlowe'ver, the current flowing through the circuit oi the winding 7' is practically not more than from .5 to 1.0% oil the motor current, so that the energy required for revolving; the windingf is small. .l-n any case the increase of the torque caused by strengthening the field is considerably hisrher. so that the power and the etficiency ol the system are increased. .l urthermore, experiments have shown that by reducing the resistance 72 the torque is increased. but simultaneously the number of revolutions is re-Qluced so that the power and the Ql'llClQDCY reduced. It will therefore be understood the he value of the resistance 72 important in my improved. system.

After the explosive engine has been start ed, the switch is in the position shown in :iull lines, whereby the conductors 72/ and are interrupted. the resistance or is short-circuited, and the conductor h is connected with the l to minnl of the generator windingf by a lead m Now the system operates as a generator. A current flows through the armature f. the lead 72H. the switch 7'. the lead 0, the held winding 3). the lead (1'. and

to the te minal of the armature wining.

The main the machine field coil for rerriilat a th .7 armature windil I I the lead m the s' itch 2'. the conductor ii. the motor winding; f. the lead the battery (1. and heel; to the iqround. or the machine frame. The first named current is used for energizing: the field. For n'oducing' the voltage for charging the battery both armature windings f and f are operative, the armature current flowing; through the winding 7 in the same direction as before and through the winding f in the opposite direction as compared to the motor action.

Preferably the conductor 4: includes an aulmzmtic or luu'nl opcmtcd switch t by means oi which the dynamo is disconnectird from t we the storage battery 6 when the explosive engine is at rest. in order that the dynamo is not accideljitally operated as a motor. The secondary battery may be connected by a switch "2; to current consumers such as a lighting); system. 7

When operating the system as a genera tor the field energizing circuit 7", 7) does not include the armature winding l have found this to be an important feature of my iin'enthrn. because thereby the energizing); of the field is made reliable which is particularly important in my improved system where the field must be energized at low speed. As is known in the art v the energizing of an electric machine more reliable where the field circuit has a low resistance, particularly where the number of: revolutions is low. In addition the resistance at the brushes interferes with the energizing of the field. Therefore a system in which only two brushesare includeth in the pres ent those of the winding f preterable as compared to a system in which also the bruslies of the winding i are included in the said circuit, so much the more as the last named brushes are those of the motor winding which ordinarily do not make as good mintact as the brushes of the generator winding: 7'.

ln the example the system is differentfrom Figs. 1 and in the following respects:

iolarity oi"; the low resiiance or motor winding f and the high resistance or generator winding the reverse from that shown in Figs. 1 and 2. To the brush of: the armature incline; f" two leads Q and a are connected, the lead providing); a connection with the hi h resistance field winding p and the lead 8 providing a connection with a series field shown in l frures 3 and i "that shown in 'Tl-H,

coil r and through a lead .5 and a switch with a lead. coni'iected to the l terminal ot the secondary batter and with a switch 7%. The switch 7' i lso adapted to male: cor iection with /1 shrough a lead 0 l in the minus ';.'i nal o'i ng with.

e lead 0 The is s in con ant connection by l the tin'niinal of the winding f the minus terminal of which is connected by a lead A with the low resistance winding Z.

For starting the engine the switch is set in the position shown in Fig. 3 for eonnecting the leads and he. Thereby the armature w ding; and the field winding Z are mnntctcd in series and current supplied thereto from the battery 6 The armature winding is in a circuit including the resistance 71 and the field winding 2) whereby the field ol' the motor part ol' the machine is strengthened.

when the 'uzris o! the system arc thus con-- l Il (l motor action of the system.

nected the current passes from the terminal of the battery 6 over 2' if, f P, frai'ne of the engine, and back to the terminal. of the battery. the current passing through the field winding Z in the direction from the bottom to the top thereof as is indicated by the arrow shown in connection with the winding. The rotating armature builds up a. current passing through the high resistance armature winding f, the bruslr thereof, through If, f, 0 21 m and. to the brush of the winding f. said current passing through the winding in the direction from the bottom to the top thereof as is indicated by the arrow shown in connection with the said winding. Therefore the windings p and Z combine to strengthen the field as has been described with refer ence to the example shown in 1 and 2.

rtfter the engine has become self operating the switches F. i are set in the position shown in Fig. 4. Now the field winding P and the series field or regulating coil 2* are energiyed so as to take part in the production of the field. A current is furnished to the battery c which passes from the terminal oi the battery and the frame of the en ine over 7*. 7 7. m". 7*" s 1". s" and the switch 7 to the terminal of the battery. the current passing through the windings 7' and 1" from the top to the bottom thereof. Therefore the current passes through the winding 1 in a direction opposite to that described with reference to Fig. 3 and the The current passing through the high resistance field coil 17 has the me direction as before that is from the bottom to the top thereof. said current passing from the terminal of the armature wii'iding f over 1 72 0 h. an. and back to the minus brush of the wiuding f.

From the foregoing it will be uuderstoo-zl that the system embodies all the z-. lv:.-mtages described. with reference to l. and 2. and. in. addition it is preferable because the number of the turns of the series" field r can be reduced by the number of the turns of the low res stance winding 1, which results in a saving in the length of the lead material and in a saving of space.

As is known to those skilled in the art. the field windings are uniforn'ily distributed on all the field poles. Therefore the wind ings 72 and I must be divided into so many sectional windings as there are field poles. so that one sectional winding p 9*, and F can be placed on each of the poles. For example, if the machine is constructed with four poles, four sectional windings of each. of the wimlings r and 7*. that is twelve windings must be disposed on the said poles.

This however is objectionable by reason of the great number of conductors between the sectional windings, because it is ditlicult to make the proper connect-ions with reference to the sense in which the coils are wound, and because there is but little room for disposing all the conductors. Therefore. I prefer the arrangement of the coils shown in F ig.

In accm'dance with the cooperation of the field and regulating windings described above the motor winding 7 and the regulating winding 7- are disposed on the same poles. and the generator winding p disposed on the intermediate poles.

In the example shown in vFig. 5 the machine is constructed with four poles and the windings. 1 r and Z are respectively divided into two sectional coils indicated, in the said figure by the reference characters 7), 72 r. 7-, and Z. Z. The winding 7/ is disposed on the pole v and the wind ing jzfi on the opposite pole W and each of the other holes 1/" and 1." carries a sectional coil 7 and 9*" and I and 1* respectively.

By thus disposing the windings instead of twelve coils only are necessary whereby the work of winding the coil.) considerably reduce-d. ln addition the numherof the connections between the coils is reduced. and the (llSPOSltlOll of the coils is comparatively simple, so that the correct connections can more easily be made.

The operation of .iny improved system is follows: hen operating the system as a motor and with normal load the same ampere-turns are produced by the windings Z. Z and p p The connections between the windings are such that each of the windings Z and Z produces a north pole. while each of the w ndings p and 2 produces a south pole. Therefore the result is the same as when uniformly distributing the coils of the windings 7) and 7 on all the poles.

\Vhen operating the machine as a generator the polarity of the coils and 32 is the same as before and they produce south poles. ...\lso the polarity of the coils Z and Z is reversed and they tend to produce south \poles, being assisted by the coils r and r of the series field or regulating winding.

Butthe number of the ampere turns of the coils p and i that of the coils i= 1" and r. 7 and the flux of the lines of forces built up by the coils and n will overcome the flux of the coils r. .7, and. T and the lines of force will pass through the coils 2", Z and. r. Tllherefore since the resultant lines of flux pass into the poles surrounded by the coils r Z and r, from the magnet fran'ie of the machine and pass out of these poles through the air gap. they will be north poles.

'l herefore the leakage of the u'iachine opcrating as a generator is materially inconsiderably exce creased, whereby the voltage is reduced particularly at high speed of the machine.

I claim:

l. In a starting; device for prime movers a series motor, a battery connected to drive the motor, a generating coil carried by the motor armature, and a coil connected across the generating coil and disposed to assist the motor field.

In. a starting device tor prime movers, a dynamotor havinga high resistance and a low resistance field, and a high resistance and a low resistance armature winding, a storage battery, means for connecting the low resistance armature and low r sistance field in series with the battery to run as a motor, and means for connecting the high resistance field: across the high resistance armature as a. generator to assist the motor field.

3. In a starting device for prime movers, a dynamotor having a high resistance and low resistance field, and a high resistance and a low resistance armature windin a storage battery, means tor connecting the low resistance armature and low resistance field in series with the battery to run as a motor, means for connecting the high resistance field and. high resistance armature as a generator to assist the motor field, and means for connectingthe armaturcs: in series to charge the battery.

4:. An electric starter for prime movers coniiprising; a motor-dynamo having an aruire provided with two armature win,-

o't difiierent numbers of turns and field windings one connected in shunt across the terminals of the armature winding of ater number of turns, a storage battery, means to connect said armature winding of smalfer number of turns and said field winding which is not connected in shunt with said storage battery for operation by the cmirent supplied by the battery, and means to connect both of said armature windings and batwrv in series with one another for =at1on 5r the system as a generator;

electric starter for nil 1e movers t motor-dynamo having an ar- V 5 .ed with two armature windi': oi lifi erent numbers of turns and l windings, a resistance, a circuit including in sense said armature winding of greater number of turns, one of said field windings, and said resistance, a storage battery, means to connect said armature winding of smaller number of turns and. said winding not included in said circuit with said storage battery for operation by the battery, and means to connect both of said armature windings and battery in series with one another tor operation oi the system as a generator.

(3v An electric starter for prime movers comp:

sing a motondynamo having an armature provided with two armature winding of smaller number of turns and one of said windings with said storage battery for operation by the current supplied by the battery, and means to connect both of said armature windings and battery in series with one another and to energize at least one of said field windings for operation of the system as a generator.

7. An lectric starter for prime movers comprising a motor-dynamo having an armature provided with two armature windings of different numbers of turns and field windings one connected in shunt across the terminals of the arn'iature winding of greater number of turns, a storage battery, means to connect said armature winding of smaller number of turns and said winding which is not connected in shunt with said storage battery for operation by the current supplied by the battery, and means to connect both of said armature windings, the field winding which is not connected in shunt and battery in series with one another "for operation of the system as a generator.

8. An electric starter for prime movers comprising a motor-dynamo having two armature windings of di'lierent numbers of turns, field w idings oi di'l'l'ferent numbers of turns, and a regulating coil arranged to build up a field, said field windingot greater number of turns being connected in shunt across the terminals of said armature which system as a generator.

9, electric start for ac movers comp" ing motoran armature provided witlr wo armature windings of ii'erent nu' a. otturusi ad indings ot different i liners of turns, and a reg ulating coil arranged to build up a field. said field winding 0:? greater number of turns being connected in shunt across the terminals of said armature winding of greater number of turns, and said field winding of smaller number of turns and regulating winding being made in sections disposed respectively on the same magnet pole and the field winding of greater number of turns being made in sections disposed respectively on poles located between the'poles carrying: the sections oi" the field windimi! oi? e-unaller number olf turns and o l the rernlliiitinp; coil, a storage battery, mea us to mnucct said armature and field windings of smaller numbers of turns in series with said storage batteryfor operation by the current supplied by the battery, and means to connect both of said armature windings, said field winding of smaller number of turns, regulating coil and battery in series with one another for operation of the system as a geneator.

In testimony whereof I hereunto :iffix iny signature in the presence of two Witnesses.

GEOR-G KARL KNAPP.

Vitnesses FRANZ REI HARD, JoHANNns Ari'rz.

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