US1241115A - Starting internal-combustion engines. - Google Patents

Description

0. HEINS & C. M. WILD. snnnuc INTERNAL'COMBUSTION aucmss.

APPLICATION FILED JUNE I2. l9l5.

Patented Sept. 25, 1917.

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ATTORNEYS weight requirements of UNITED STAT Es PATENT OFFICE.

OTTO HEINS, OF NEW YORK, N. Y.. AND CHARLES M. \VILD, OF SPRINGFIELD, MASSA- CHUSETTS, ASSIGNORS TO BOSCH MAGN IORATION NEW YORK.

STARTING INTERNAL- ETO COMPANY, OF NEW YORK, N. Y., A COR- GOMBUSTION ENGINES.

Patented Sept. 25, 1917.

Application filed June 12, 1915. Serial No. 33,726.

To a whom it may concern Be it known that we, OTTO Hams, a subject of the Emperor of Germany, residing at No. 336 West 88th street, in the city, county, and State of 'ew York, and Germans M. lVILD, a subject of the Emperor of Germany, residing at No. 14 Springfield street, Springfield, county of Hampden, State of Massachusetts," have invented certain new and useful Improvements in Starting Internal-Combustion Engines; and we 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 'appertains to make and use the.

same. v In starting internal combustion engines from rest, it is preferable to give the crank shaft of the engine a quick turn, a lower acceleration for a longer pcri d, because the total energy required to reliably start into action the carburetor and the ig nition system if it embodies a magneto, and to cause the engine to pickup, is less, time of starting is less, and usually the engine starts at a lower speed, which further reduces the time and energy required. The difference is particularly important when an electricmotor is used for starting, inasmuch as the size of the starting battery is directly affected and also the space and the entire starting In using an electric motor of the series type, which is well adapted for the purpose on account of its high starting torque and its speed-torque characteristic, difficulty sometimes arises when a quick turn is produced like "the rapid half or quarter turn of the crank when starting by hand, because, if the acceleration of the engine from rest is designed to be high, then the speed to which the engine is brought at this acceleration may be below the speed at which the engine starts into action under its own power, which speed is herein termed the critical speedff] This is particularly true. when theengine is'cold or when unequipment.

usual high starting resistance in the engine rather than the .ing resistance and bring the engine to a speed ample under theworst conditions likely to bepresent, which speed is herein termed the abnormal critical speed. This speed is higher than necessary for normal conditions, and it followsthat the average acceleration of the engine to its critical speed is lower than would otherwise be attained with'the same starting motor.

In order to keep the starting equipment small and light, advantage has been taken of the fact that the starting period is of very short duration. Thus, it is usual practies to work the motor at very high output, even up to the point of maximum output which it is capable of developing. By making the point of maximum output occur at the normal critical speed of the engine, the average acceleration of the engine up to that speed is substantially a maximum, but if, 'on account of abnormal conditions, the engine does not pick up at this point, the acccleration'falls off rapidly thereafter, first on account of the increasing speed and secondly on account of the decreasing output, the rate of decrease depending upon the characteristics of the motor. On the other hand, if'the maximum output of the motor occurs at the speed at which the engine picks up under the worst conditions of operation, thenthe average acceleration to the normal critical speed at which the engine starts into action under normal conditions is considerably lower thanbefore;

We have discovered'that a series motormay be worked at a higher average output than it is at present required to do in starting an internal combustion engine from rest without heating the motor to a dangerous temperature, and we have taken advantage of this condition in providing a methodof starting wherein I the motor will reliably start the engine under all likely conditions in a minimum time, that is, at a maximum everage acceleration, and with decreased consumption of energy. In doing this, the equipment is preferably operated in such manner that the motor attains its maximum output at about the normal critical speed of the engine, but instead of allowing the output of the motorto decrease in case a higher speed should be necessary, the speed-torque characteristic developed by the motor at the en ine shaft, and preferably at the shaft of than once,'and in fact the change fromone- I speed-torque characteristic to -a nother. may

' point'of first maximum output of the motor [series electric be made gradually so that the average out-.

putof the motor in this period' is thereby a maximum. Although we prefer to have the coincide substantially with the normal criticalspeed of'the engine,'yet'.it is possible within o'ur'method' of starting to have the .maximum output occur before this point and thereby further increase the average '-acceleration and decrease the time of starting and the energy consumption to the extremity thatis possible withinsafe heating limita tions of the motor.

Thcre are various ways in which the speed-torque characteristic developed by a motor at the engine shaft may be; appropriately changed during the starting period. For instance, the s cedtor que characteristic of the motor itsel may be appropriately changed by decreasing the excitation of the field windings of themotor,

or-by shunting the field windings, or by series-parallel grouping thereof, and this action may be repeated, if desired, or it may be accomplishertl gradually over a range of speed. A similar effect may be produced by suitably altering, the ampere-turns of the armature or by cutting out some of the coils thereon, or by shunting the armature. .Furthermore, the speed-torque characteristic developed by the motor at the engine shaft may be appropriately changed by change speed gearing between the motor and the engine as described and claimed in our copending application Serial ,Number 33727, filed concurrently herewith. In all cases the starting equipment is designed to produce a high average acceleration from rest to normal critical speed of the engine, preferably by adapting the motor to reach the first point of'maximum output substantially at the time the engine reaches its normal critical speed. If the engine does not pick up at that time, its speed may be -further increased at a rate which, though less than before, is higher than the rate which would occur if the motor were allowed to continue its operation after attaining the first point of- -maximum output without the change introthe field excitation of the motor may be decreasedby substituting other field coils of less ampere turns;

'the winding 5.

Fig. 2 shows an arrangement whereby the field coils may be changed from series to v parallel connection with each other;

voutput characteristics of a motor arranged in accordance with our invention, the armature resistance being disregarded and the magnetic flux being assumed 'to increase in constant proportion to the magnetizing ampere-turns. a

In Fig. 1, the electric starting motor has its armature 1 connected to the shafit of the internal combustion engine 2 by suitable gearing 3, and is provided with a series field winding 4 and another series field winding 5 of fewer turns. The winding 4 is connected to the contact 6 of a switch, and the 1 winding 5 is connected to the contact 7 the battery 9 being connected on one side to the contact 8 and on the other side to one commutator brush. Upon depressing the switch lever 10, the battery 9 isfirst connected to the series field winding 4. and then to the series field winding 5, the field of the motor first being magnetized to a normal degree by the winding-4 and then to a lesser degree by According to Fig. 2, the series field windings 4 and 5, which in this case have the same number of turns, are

first connected in series by the switch 10 to 106 produce the normal magnetization of the field of the motor, and are then connected in parallel by throwing the switch lever to its upper position to thereby decrease the field magnetization. field winding 4 which is connected to the battery 9 by the switch 10 to produce normalexcitation of the motor, and which is connected to the battery in parallel with the shunt 11 when the switch 10 is further depressed to thereby produce a weaker field magnetization. The arrangement shown in Fig. 4 is such that the field winding 4'remains connected to the battery 9 through the switch 10, while theacross the armature terminals is disconnected by opening the switch 13. the result being to increase the speed of the motor by increasing the armature ampere turns According to Fig. 5, windings 14 and 15, either of which is connected in series with the field winding 4 by the switch 10. The armature winding 14 provides a number of ampere turns suitable for the normal "operation of the motor, and 130 In Fig. 3, there is a single 110 shunt 12 connected the armature has two and. if desired the winding provides a-.fewer number of teristic of the motor so that'the. motor tends to attain a second point'of maximum output equal-to or greater than the first one attained under normal conditions of operation, the change may bemade in this way more than once during the starting period, or gradually so as 'to maintain the motorat the maximum outputover a considerable period by gradually altering the magnetomotive force effective on the magnetic circuit of the motor, as, for instance,

- by gradually decreasingthe number of turns included in the winding 5 2 0 gradually decreasing the resistance of the shuntin Fig. 3' or increasing that of Fig. 4. Accordingto Fig. 6, them'aximum output of the motoris. caused to recur one or more times'by '25 motorspeeding up increasing zthe number of cells in the battery 9 connected to the motor, the at each increase. F g. 7

shows-theoretically the speedoutput curves of aseries electric motor with different field excitations or with different armature ampere turns. If the motor is a-d uSted tor curve-I, the output would attain-its maxi- I stance, by making the. change at nu m value it and rangem'ents substantially then decrease, the acceleration decreasing at a rapid rate therewith Now, by accordance with'one of the-foregoing arat the time that the value a of curve I is attained, for inlb, another output 0 theoretically equal to a is produced by the motor. Similarly, by changing over it]? the characteristic III at point (23, the

aiiimum 'outprit again recurs at c. It will also be apparent that the output may theoretically be maintained substantially constant along the line a, e by introducing the gradual change of conditions hereinbei'ore referred to. In this way,- the average horse power output of the motor during the starting period is materially increased, thereby increasing the average acceleration of the engine to its critical speed, whether the critical speed is at a'normal or at an abnormal value.

In practice, and particularly with the series electric motors ordinarily used for starting internal combustion engines, the point of second maximum output is greater than the. first and the third greater than the second, the eifect being to increase the average acceleration between the normal and abnormal critical speeds, and, therefore, from rest to the abnormal critical speed, above the theorgtical-values indicated by the curves of Fig.

It will be understood from the foregoing,

of Fig. 1, or by' changing the-motor to. curve 11 in that the desirable quicl; turn obtained by hand in starting a small engine is 'more closely. approached by thismethod of starting by a motor than hashereto iore been posthe first maximum output than could otherwise be attained, even if the abnormal critical speed should be beyond the final point of maximum output. Furtherfore, the average acceleration obtained in this way from rest to'the first point of maximum output is increased because the'speed of is then lower than would be appropriate if the output of the motor continually de creased after this point, as is the casein prionsystems. Finally, the ailerage accelorationthroughout the entire starting period may be, in accordance with our preferred method of starting, themaximum attainable withinthe heating limitations of the motor. Notonly the time of starting is decreased as a result'of the higher average acceleration to-the critical speed, whether normal or abnormal, but the energy consumed is less and the sizeand weight of the entire starting equipment, including the but tery, are reduced.

It is to be understood, of course, that in operating in accordance with our method of starting, the operator so times the actuation of the switch or switches that the characteristic of the motor is changed at the proper points. short duration, the switch or switches may be so designed that a continuous movement of a foot pedal produces the proper se quence of connections and at the time required in order to accord with the method of starting hereinbe'fore described.

Having thus described our what we claim is:

1. The method of bringing an combustion engine up to its on by means of avmotor co mected thereto, 7

which consists in initiating the starting op eration with the motor arranged for a pre determined speed-torque characteristic, and changing the motor to a. different speedtorque characteristic at substantially the the engine the I Inasmuch as the entire period is of time the engine reaches its normal critical speed. I

The method of bringing an internal combustion engine up to its critical speed by means of an electric motor connected thereto, which consists in connecting a source of current supply to the motor terminals to cause the motor to develop a predetermined speed-torque characteristic, and changing a circuit of the motor to change the motor to a different speed-torque characteristic at substantially the time the engine reaches its normal critical speed.

4. The method of bringing an internal combustion engine up to its critical speed by means of a series electric motor connected thereto, which consists in connecting a source of current supply having a constant voltage to the motor terminals to cause the motor to develop. a predetermined speedtorque characteristic, and changing a circuit oi" the motor tochange the motor to a dili'crent speed-torque characteristic at substantially the time the engine reaches its normal critical speed.

The method of bringing an internal combustion engine up to its critical speed by means of an electric motor connected there-- to, which consists in connecting a source of current supply to the motor terminals to cause the motor to develop a predetermined speed-torque characteristic, and changing the motor to a different speed-torque characteristic at substantially the time the engine reaches its normal critical speed by altering the magnetomotive force of one of the elements of the motor.

The method of bringing an internal com-- bustion engine up to its critical speedby means reaches its normal critical speed by decrees 7 ing the field ampere-turns of the motor.

7. The method of bringing an internal combustion engine up to its critical speed by means of an electric motor connected thereto, which consists in adapting the motor to reach its maximum output at substantially the time the engine reaches its normal critical speed, and changing the speed-torque characteristic developed by the motor at the engine shaft during the starting period to cause the motor to reach another point of maximum output at a higher speed.

8. The metl 0d of increasing the average acceleration in bringing an internal combustion engine up to its critical speed by 11 ans of an electric motor connected thereto, which consists in connecting the source of current supply to the motor terminals, adapting the motor to reach its maximum output at substantially the time the engine reaches its normal critical speed, and decreasing the field ampere-turns of the motor at substantially that time.

In testimony whereof we allix our signatures, in presence of two witnesses.

OTTO IIEINS. CHARLES M. WILD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0.

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