US1240973A - Starting internal-combustion engines. - Google Patents

Description

O HEINS & C. M. WHLD,

STARTING INTERNAL COMBUSTION ENGINES.

. APPLICATION FILED JUNE 12, 1915.

1,240,973. Patented Sept. 25, 19177..

3 SHEETS--SHEET 3.

$4 Z: N A03 ATTORNEYS UNITED STATES PATENT OFFICE.

OTTO HEINS, OF NEW YORK, N. Y., AND CHARLES M. WILD, OF SPRINGFIELD, MASSA- CHUSETTS, ASSIGNORS TO BOSCH MAGNETO COMPANY, OF NEW YORK, N. Y., A

CORPORATION OF NEW YORK.

STARTING INTERNAL-COMBUSTION ENGINES.

Application filed June 12, 1915.

To all whom it may concern:

Be it known that we, ()T'ro HEINS, a subject of the Emperor of Germany, residing at 336 \Vest 88th street, city, county, and

6 State of New York, and CHARLES M. VILD,

"' a subject of the Emperor of Germany, re-

siding at 14 Springfield street, Springfield. I Hampden county, State of l\Iassachusetts, 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 apper- 15 tains to make and use the same.

In starting internal combustion engines from, rest, it is preferable to give the crank shaft of the engine a quick turn, rather than a lower acceleration for a longer period,

because the total energy required to reliably start into action the carbureter, and the ignition system if it embodies a magneto, and

to cause the engine to pick up, is less, the time of starting is less, and usually the en gine starts at a lower speed, which further reduces the time and energy required. The difference is particularly important when an electric motor is used for starting inasmuch as the size of the starting battery is 0 directly alfeoted and also the space and weight requirements of the entire starting equipment. 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 spee ltorque characteristic, diiiiculty 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 40 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 and its auxiliaries will reliably pick up. which speed is herein termed the critical speed. This is particularly true under abnormal conditions when the engine is cold or when unusual high starting resistance in the engine must be overcome. as for instance on account of frozen bearings or insufficiently lubricated pistons. In order that the motor may reliably start the engine.

at all times. it has been customary to install a starting equipment designed to overcome the starting resistance and bring the engine Specification of Letters Patent.

Patented Sept. 25, 1917.

Serial No. 33,727.

to a speed ample under the worst conditions l1kely to be present. This speed is higher than necessary for the ordinary conditions. and it follows that the 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 practice to work the starting 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 iiormal critical speed of the engine, the average acceleration to that speed is substantially a maximum, but if, 011 account of abnormal conditions, the engine does not pick up at that point, the acceleration falls off rapidly thereafter, first on account of the increasing speed and secondly on account of the decreasingoutput of the motor. the rate of decrease depending upon the characteristics of the motor. On the other hand, if the maximum output of the motor adjusted to occur at abnormal critical speed, then the averageacceleration to the normal critical speed is considerably lower than before.

We have discovered that, a series motor may be worked at its point of maximum output for a longer time 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 method of starting wherein the motor will reliably start the engine un der all likely conditions in a minimum amount of time that is, at a maximum 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. but instead of allowing the output of the motor to decrease in case a higher speed should be necessary, we provide a range of speed throughout which the motor substantially maintains its maximum output, or we cause the maximum output of the motor to recur one or more times. Although we prefer to have the maximum output of the motor coincide substantially with the normal critical speed, yet it is possible within our 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 that is pos sible within safe heating limitations of the motor.

There are various ways in which a series motor may be caused to maintain its maxi-- mum output over a range of speed or by which the maximum output may be caused to recur one or more times. For instance, the speed change gearing between the motor and engine may be altered in such manner that the reduction ratio is decreased as the speed attains certain values, which may correspond substantially with the points of maximum output of the motor. By altering the ratio graduallv, the maximum output may be maintained constant, and by altering it in one or more steps, the maximum output may be made to recur one or more times? Besides these mechanical methods, the maintenance of the maximum output or .the recurrence thereof may be produced electrically by operating on the field or armature windings, or on the voltage applied to the motor terminals, as described and claimed in our copending application, Se-

rial No. 33,726, filed concurrently herewith.

In the accompanying drawings illustrating suitable apparatus for carrying out' the herein described method of starting internal combustion engines from rest,

' Figure 1 is a side view of the installation on an automobile, for example;

Fig. 2 is a central vertical section on-an enlarged scale of the speed change gearing between the motor and the engine;'

Fig. 3 is a section on line 33 of Fig. 1; and

Figs. 4 and 5 are sections on lines 4-4 and 55, respectively, of Fig. 2.

Referring particularly to Figs. 1 and 3, the electric motor 1 is of the direct current series type of suitable speed-torque characteristic. The shaft 3 extending from. the gear box 2 carries a pinion 4 meshed with a loose gear 5. The spring pressed pawls 6 are carried by a rotatable frame 60 fast with the gear 5. The ratchet wheel7 and the pinion 8 are tight on the shaft 12, and the pinion meshes with the gear 9 tight on the crank shaft 10 of the internal combustion engine 11. The gearing between the shafts 3 and 10 has a proper reduction ratio to adapt the speed of the motor to the starting speed of the engine, and the pawl and ratchet forming an over-running clutch be tween them disconnects the engine from the motor when the engine gets under way.

Referring now to Figs. 2, 4 and 5, the

armature 13 of the motor has a shaft 14 supported on ball bearings 15 in the end plate 16 and it carries a pinion 17. Both of the intermediate pinions 18 mesh with the pinion 17 and with the internal gear 19, and are loose on studs 20 extending from the bracket plate 21 which is fastened on the shaft 3. In the example illustrated, pinions 17 and 18 are of the same size, and thus the planetary gearing formed thereby produces a speed reduction of four from the shaft 14 to the shaft 3 when the internal gear 19 is held against rotation, the two shafts rotating in the same direction. This speed ratio may be altered if desired by changing the relative size of the gears 17 and 19.

The internal gear 19 is bolted to the two bearing plates 22 and also to a coupling member 23 having an internal cone surface at 24. A cooperative coupling member 25 is screwed to the sleeve 26 and is in surface contact with the ring 27 which is pivoted on the pin 28 and fastened to a forwardly directed member 29. The linked levers 30, 31, 32 embody a pin and slot connection 33 with lost motion and also a cam 51 cooperating with the member 29 when the foot pedal 34 is depressed by the operator, the tension sprin 35 tending to force the pedal to its raise position. The internal gear 19 is held against rotation, during the rotation of the shafts 14 and 3, by the coupling member 25, which is engaged with the coupling member 23 and also locked to the non-rotatable ring 27 by the ball clutch 36, the compression spring 37 holding the parts in this position. The sleeve member 38 is keved at 39 to the shaft 3 and carries the clutch disks 40 separated at this time from the disks 41 which are carried by the coupling member 23. Thus, at this time, the shaft 3 is rotated at quarter speed by the shaft 14, through the gears 17 and 18. The shaft 3 rotates on bearings 43 and 44 and the sleeve member 38 rotates against the thrust ball bearing 45.

Upon depression of the foot pedal 34 to its lowermost position shown in broken lines in Fig. 1, the ring 27 is swung back on the pin 28 by the action of the cam 51 against the member 29 until the disks 40 and 41 are engaged by intimate surface contact. Also the ball clutch 36 is released and the coupling members 23 and 25 are disengaged. The shafts 1-l and 3 then rotate as a unit, that is, without speed change, inasmuch as the pinion 17 is fast on the armature shaft 14 .while its internal gear 19 is then fast with the shaft 3, the pinions 18 bodily rotating around the shaft 1.4 without rotation on their studs 20.

The motor 1 is electrically connected to the-battery 46 throu h the wires 47, the switch 48 being interposed in the circuit.

The switch lever 49 is attached to the lever between the battery and the motor before all of the lost motion in the pin and slot connection 33 is taken up, and also to maintain the circuit closed when the foot pedal is in its lowermost position. Upon release, the spring 36 raises the foot pedal to its uppermost position wherein the circuit is opened at the switch 48.

Our preferred method of operation is car ried out by this apparatus in the following way: When the foot pedal 3% is in its uppermost position, the battery is disconnected from the motor, but during the first part of the depression stroke the switch i8 is closed and the motor starts to turn the engine at a high acceleration, due to the speed reduction in the planetary gearing and in the other gearing between the shafts 14 and 10. The depression of the foot pedal is so timed by the operator that substantially when the motor reaches its maximum output, the internal gear 19 is released for rotation. The shafts It and 3 then rotate as a unit, in the same direction as before, and the speed reduction between the motor and engine is decreased to half its former value, that is, relatively to the speed of the motor, the speed of the engine is twice its former value.

In attempting to double the speed of the shaft 3, resulting from this speed change, the motor immediately slows down, drawing more current from the battery and increasing the acceleration which existed just previous to the gearv change. Afterward, the

motor starts to speed up again to a new point of maximum output, substantially equal to the first, the acceleration which occurs in the meantime and the speed at which the second point is reached, depending among other things upon the speed-torque characteristic of the motor.

It will be understood from the foregoing that the desirable quick turn attained by hand in starting small engines is more closely approached by this method of starting by motors than has heretofore been possible. By decreasing the ratio of speed reduction from the motor to the engine during the starting period, a higher average acceler ation throughout the entire starting period is secured, compared with prior systems. By providing such speed reduction in the gearing between the motor and engine that the first point of maximum output is reached substantially at the normal critical speed, as we prefer to do, the speed at which the engine will reliably pick up under the worst likely conditions, is reached at higher average acceleration from the first point of maximum output than could otherwise be at tained, even if the abnormal critical speed should be beyond the second point of maximum output. Furthermore, the average acceleration obtained in this way from rest to the first point of maximum output is increased because the speed of the engine is then lower than would be appropriate if the output of the motor continually decreased after this point, as is the case in prior systems. Finally, the average acceleration throughout the entire starting period may, in accordance with our preferred method, be made the maximum attainable within the heating limitations of the motor, if the maximum output is maintained after it is once reached.

()ur herein described method also includes the idea of providing more than two points of maximum output by providing more than two speed ratios of operation between the armature shaft and the engine shaft, and it also includes the idea of maintaining the maximum output of the motor after it is once reached by providing a gradual change in the speed ratio during this period. In starting in accordance with our method, not only is the time of starting 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 size and weight of the entire starting equipment, including the battery, are reduced.

Having thus described our invention what we claim is:

1. The method of bringing an internal combustion engine from rest to its critical speed by means of a starting motor connected thereto through speed change gearing, which consists in decreasing the reduction ratio of the speed change gearing during the starting period; substantially as described.

2. The method of bringing an internal combustion engine from rest to its critical speed by means of an electric motor of the series type connected thereto through speed change gearing, which consists in decreasing the reduction ratio of the speed change gearing substantially at the time that the motor attains its maximum output.

3. The method of bringing an internal combustion engine from rest to its critical speed by means of an electric motor of the series type connected thereto through speed change gearin which consists in causing the maximum output of the motor to recur by decreasing the reduction ratio of the speed change gearing after the motor first attains its maximum output.

h The method of bringing an internal combustion engine from rest to its critical speed by means of an electric motor of the series type connected thereto through speed change gearing, which consists in adapting the motor to reach its maximum output substantially at the normal critical speed of the engine, and decreasing the reduction ratio of the speed change gearing at substantially said speed.

5. The combination with an internal combustion engine, a starting motor therefor,

and a source of energi for the motor, of means for increasing t e average acceleration in bringing the engine from rest to its normal critlcal speed comprising control means which, upon operation, first connects the source of supply to the motor and then operates on the speed change gearing to decrease the reduction ratio thereof.

7. The combination with an internal combustion engine, an electric starting motor therefor of the series type, a source of current supply for the motor, and a switch con nected between the source of current supply and the motor, of means for increasing the average acceleration in bringing the engine from rest to its critical speed, comprising speed change gearing between the motor and the engine, and a lever, which, upon operation, first closes the switch to start the motor and then operates on the speed change gearing to decrease the reduction ratio thereof.

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

OTTO HEINS. CHARLES M. WILD.

Witnesses:

V. W. KLIEsRA'rH, ROLF LINDENHAYN.

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