US1501508A - Electrical system fob aircraft - Google Patents

Description

Jul 15 1924. 1,501,508

L. m-wooLsoN IFZLEGTRICAL SYSTEM FOR AIRCRAFT Filed Nov. 14. 1917 2 Sheets-Sheet 1 all] INVENTOR A .w HJ

TORNEYs July; .15 1924 L. M. WOOL-SON ELECTRICAL SYSTEM FOR AIRCRAFT Filed Nov. 14. 1917 2 Sheets-Shem. 2

- IN ENTOR LAO-.4 xlum V MJREWI we d s! 1 9 STATES BATENT LION L Q 'SQ DAYT 03in, ASSIGNQR, B final-m 1'0 AY ON; ENG N RING LABORATORIES oonrm, Aconrona'rronon 031g;

ELECTRICAL SYSTEM FOR AIRCRAFT.

Application filed l lovcrnber 14, 1917. Serial No. 201,974.

the blocks of the V at a relatively small To all whom it my concern:

Be it known that I, LIONEL M. Woonson, a citizen of the United States, and a resident of the cit Y of Dayton, countyof Montgbmery, and gtate of Ohio, have invented an Improvement in Electrical Systems for Aircraft, of which the following is afspeci fication. I This. invention relates to electrical systems for internal combustion en ines, and with regard to its more specific eatures to electrical' systems for eng nes designed for air lane 'propulsion'. ne of'the objects thereof is to provide an ignition system involving apparatus of simple, light and rugged construction, specially suitable for modern airplane engines of certain types."

Another object is to provide in apparatus of the above type an ignition system which will function efliciently under all conditions of operation and which is unlikely to break down.

Qtherobjects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangement of parts which will be exemplified. in the construction hereinafter set forth, and t lge scope of the application of which will e indicated in the following claims.

In the accompanying drawing wherein is shown one of various 'pomible embodiments of the several features of-this invention, Fig. 1 is an end view of the engine showing the parts .of the ignition system in a preferred relation.

Fig. 2 is a diagrammatic view of the ignition circuits thereof and Fig. 3 is a detail view of the interrupter cams showing their preferred angular relation.

Similar reference characters refer to similar parts throughout the different views.

of the drawings.

In the specification and claims I intend the -term V-t 0 engine to apply to any engine in w ich the axes of some cylinders are at an angle to those of others.

As conductive to an understanding of some of the features of this invention, it may be noted that in airplanes in which, as is well known, the V-type of engine is particularly advantageous, greater efiioiency of the vehicle is secured y arranging :in the width of the engine so that anarrower fuselage may be employed with consequent reduction of the resistance of; the atmosphere a ainst pro ress of the vehicle. I This a teration o the conventional form of V*-type engine makes-it desirable to introduce certain chan' s in the conven tlonal ignition system wit a view to scouring a high 'efliciency of action, and one of the objectsofthe invention as abovenoted is to bring about such eflici'enc Referring now to 'Fi 1 of the drawings, there is shown an eiglt 'cylinderengine 1 of the V.-type having an an 1e between its cylinder blocks 2 and 3 of instead of'the angle" of 90 degrees, usual in eight cylinder engines of the V-typ'e. The term block is used in the specification and claims, without regard to the manner in which the cylinders are cast, the term being used generically as meaning group of; cylinders v regardless of. construction. It is obvious that after firin of a c linder in the left hand block of a our cyc e eight 0 linder en ineof the V-t' with its bloc s disposed as in Fig. 1, t e explosion in the next cylinder in order of firing of the right block, will take lace after a' 45' degree'turn of the cranks aft. Thereupon a turn of 135 degrees of the crankshaft will be necessary before. the next ex losion will take place in acylinder on the. eft hand block, and thus explosionsexplosions, to define the angle betwcen' crankshaft positions for successive explosions.

A preferred location of the ignition apparatus for the engine is'indicated in Fig.

ut 45 degrees 1. Mounted substantially centrally between blocks 2 and 3, and near the apex of the V is'a current enerator 4, driven preferably. at twice .cran -shaft speed, and having a .special construction of timer T, preferably splined on its shaft, as shown at 55, and driven thereby. For reliability of action,

' two i'.substantially independent ignition systerns are preferably provided, both deriving their, current from the generator 4. These ignition systems are substantially dupli-' cates, an induction coil 5 being preferably mounted on one cylinder block, and a similar induction coil 6 on the other, there being spark plug 16 is connected to contact 60 on the ad acent distributer and spark plug 15 of the same cylinder is connected to contact 61 bff the distributer associated with the other cylinder block. Similarly spark plug 16" on a cylinder of the right hand block is connected with contact 63 of the adjacent distributer, and spark plug 15' of the same cylinder is connected to contact 64.- of the distributer 7 associated with the left hand block. In this manner-the two spark plugs of each cylinder are connected one with the the distributer on the same block and the other with the distributer on the other block. Thelispark plugs of each-cylinder are thus connected tobe caused to fire simultaneously, one being energized by way of distributr 'Zjand the other by way of distributer 8. Theconnections from each distributer are of course in the same order as the cylinders are designed to fire. The. engine as is noted is preferably provided with overhead camshafts' 17 to which the distributers are at; tached and by which they are driven.

" It may here be noted that the duplicateignition systems not only furnish protection in case one systemshould break down-in normal operation, but lhe induction coils and distributers are so spaced that in the case of airplanes used in warfare a small; projectile is unlikely to simultaneous- 1y cripple both systems. An auxiliary ignition system used for starting is shown mounted at 50. The detailed construction of. all. of the ignition systems will be more fully described below.

Referring now to Fig. 2, there is shown preferably a generator. 1- having main rushes 56 and 57 in neutral position, an auxiliary brush 58 and the field coil 59 connected between brushes 5? and 58, which ar- *rangement will reduce substantially constant current wit varying speeds. It is to 12. The two cams are substantia be understood that other regulating means for this result may be employed to advantage. ,One of the generator terminals is preferably grounded or connected to a metallic structure of the airplane. The generator leads current to the primary 9 of an induction coil 5 and from there through interrupter contacts 11 back to ground or a metallic structure of the machine, the conis led to arm 35 of a distributer 7 of special construction which will be described in greater detail below.

As described above, it is preferable to provide two separate ignition circuits, the second circuit being substantially identical with the first just described, the induction coil 6 having a primary 10 and a secondary 39, the second interru ter being shown at 12 and being bridged y condenser 14 and the second distributer being shown at 8.' It is, of course, to be understood that the second 'ignition circuit ma be dispensed with, but

there are specially eneficial features of operation resulting from its use.

For reliability of action and in accordance with the peculiar construction of engine above described, the ignition system is preferably dtsigned to produce its ignition sparks at unequal intervals corresponding to crankshaft rotations of 45 degrees and 135 degrees alternately. This is brought'about by employing the special construction of cams shown at 19 and 20. These cams are shown in Fig. 3, the cam 19 operating contacts 11 and the cam 20 operating contacts ly identical and operate in synchronism, so that the description below Wlll apply to either. As shown, the operating irregularity 21 which opens the interrupter 11 to produce a spark is succeeded after a 90 degree turn of the cam by operating irregularity 23, the contacts having automatically closed by thesaction of spring 52 immediately after irregularity 21 passes roller 22. After operating irregularity 23 is passed, the interru ter contacts are maintained opened until axls 25 reaches roller 22 when they again close and again reopen when irregularity 21 reaches roller 22. It is thus seen that the opening of the be at alternate angular distances of 22% de-,

' grees and 67% degrees. Since the distributers are operated .by the camshafts and at one-half crankshaft speed, the angles of 2% and-67% degrees correspond respectivel to angles of 45 degrees and 135 degrees 0 the crankshaft. It is thus seen that the ignition system disclosed will produce sparks at a=l ternate intervals of 45 degrees and 135 degrees of crankshaft position.

It is to be noted that the angular. distance between the closure ofthe cam at 25 and the irregularity 21 is the same as that between the closure of the interrupter at 26 and the irregularity 23. By this arrangement, a uniform amount oftime is allowed for building up of the magnetic flux for the primary coil regardless whether a 45 degree interval of crankshaft rotation or a 135 degree interval precedes firing. The camin its operation it is seen does not permit a reclosure of the interrupters immediately after irregularity 23 has caused the opening, but it maintains the contacts in open position until point 25 reaches the roller. The cams as is seen are diametrically symmetrical in form. If the interrupter contacts were allowed to close a uniforminterval aftertheir openingit is clear that a hotter spark would result after a 135 degree interval than after a 45 de es interval so'that the firing of the cylin ers of block 3 would be less efiicient than that of block 2 bringing about a very undesirable irregularity of action of the engine.

For starting the engine, since the generator 4 does not then operate, a separate source of ignition current for starting should be provided arid the spark should preferably be retarded. For this reason, an auxiliary ignition system is provided for-the starting operation. This system is preferably of the .vibrator type to produce a shower of sparks particularly effective during starting.

Referring to Fig. 1 there is shown a dry or other light battery 27 which is grounded or connected to a metallic structure of the airplane when switch 32 is placed on contact S, and will when contacts are closed lead current through primary coil 28, contacts 65 and back to ground. When interrupter contacts 65 are closed, this induction 0011 which. has the usual vibrator contacts bridged by condenser 52 will open the battery circuit overcoming the resistance of the contacts repeat this cycle, vibrating with great rapidity in the well known manner. It is thus seen that while contacts165 are closed, a succession of impulses is induced in the secondary for producing a shower of ignition sparks as more fully described below.

Cam 18 ,whichoperates contacts 65 of the auxiliary ignition system may, as shown, .be substantially identical in shape and size with cams 19 and 20, but, unlikethe latter, the operating irregularities of: cam: 18, for reasons just outlined, are the depressions 40 and 41 which bring about closure instead of opening of contacts 35. As shown, these operatlng irregularities are retarded 90 degrees behind the operating irregularitiesof cams 19 and '20. The cams 19 and 20 are fixed on the generator shaft with a 90 degree lead with respect'to the starting cam, and the cams turning at twice crankshaft speed, cams 19 and'20 will produce a spark advanced by 45 degrees with respect to that produced by starting cam 18.

The secondary'29 of the induction coil leads to a conducting ring 30 on distributer 8 and is by means of this ring 30 brought into electrical connection with a distributer arm 31 maintained preferably non-adjustably 22% degrees behind the main distributer arm 36 above described. A conducting strip 31' on arm 31 connects ring 30 successlvely with the distributer contacts. The conductin portion 36 of arm 36 is preferably-de ected as shown at 53 to be out of conductive: relation with ring 30. Either conducting strip 31 or 36 or both of them are preferably embedded in the insulating material of the corresponding arm to prevent jumping of spark from one strip to the other. Since the distributer rotates at onehalf crankshaft s eed it is seen that the an lar distance 0 22% degrees between distri ute'r arms corresponds to an angle of 45 degrees of flywheel position. If the arms 35 and 36 be properly synchronized with contacts 11 and 12, that. is if these contacts are arranged to open the instant the arms each reach a distributer contact, then the ignition circuit for starting will without further adjustment produce a spark retarded 45 degrees behind the normal operating spark By this arrangement, if the normal operatin spark be made to occur at a 45 degree a Vance, the spark for starting will occur at top dead center of each piston. If as is the case in some types of engine, a'spark advance of less than 45 dees is desired, such adjustment is readily effected. 'The ignition spark for starting because of its non-adjustable relation of 45 degrees behind the normal operatin ignition spark will in such case occur ehind to center, which results in efliclent operation. In accordance with the characteris-- cause rapid alternate opening and closure of.

'need be made in the operation of the machine, the advance .having once been properly set. The operating ignition circuit having been properly timed, the auxiliary ignition apparatus for starting will without further adjustment operate efliciently 45 degrees behind the main ignition apparatus as above indicated.

The switch 32 has two positions S and O. 1

As described above, when in position S the ignition circuit for starting is closed. When laced in intermediate position indicatedby ,this circuit is open, and when 111 os1- tion 0, the main brushes 56 and 57 o the generator are short-cireuited substantially as in the case of the stoppin switch of a high-tension magneto, rendering this generator incapable of producing ignition current. When switch 32 is in any position other thanposition O, the generator may be operative. A coil spring 66 is preferably located to be compressed when the switch is in position S so that the ignition circuit for starting is closed only when maintained in this position by the hand of the operator.

The construction of the device having been above set forth, the operation is substantially as follows: The airplanev driver holds switch 32 in position S, and the engine is thereupon cranked either by hand or by electric or other power. As soon as an irregularity 40 or 41 on cam 18 brin about a closure of contacts 'the battery 27 will lead current through the primary 28 and the primary circuit. The secondary 29 will, therefore, in well-known manner, lead 1mpulses of current to ring 30 and from there throu h arm 31 in succession to the various c lin ers as arm 31 is turned by the camshaft. In this manner a shower of sparks will be caused to take place in each cylinder until the engine runs under its own power. IV hen this occurs switch 32 may be allowed to open to place the auxiliary ignition circuit out of action and this switch is then placed in position R. The generator 4 will now be operating with suflicient speed to generate ignition current, and when the simultaneously operating interrupter contacts 11 and 12 are closed, the two main ignition circuits will be closed the one from ground, or a metallic structure of the 'machine, through the enerator, primary coil 9 contacts 11 and back to ground, and the other through primary coil 10, interrupter 12 and back to ground. As soon as the irregularities 21 or 23 on the cams 19 and 20 cause the interrupters to open, the arms 35 and 36 being then in conductive relation each with a distribut-er contact, a current impulse will be sent by the secondaries of the induction coils 5 and 6 res ctively to the two spark plugs of that cylinder corresponding to the position of the arms. As is readily understood this operation will be repeated at alternate intervals of a 45 degree and 135 degree turn of the crank-shaft resulting in proper ignition. When it is desired to stop the operation of the ignition system, the switch 32 is moved to position 0 to short-circuit the generator by grounding brush 57. In view of the shape of the cams the time for building up flux for the primary as above described is the same for all cylinders.

If'switch 32 is allowed to remain closed after starting, it will merely produce a harmless ignition spark 45 degrees later than the generator spark and nothing objectionable will occur beyond unnecessary depletion of dry battery 27.

As is seen the ignition enerator is not supplemented by a stora e attery for running, but alone supplies t e generative force for the ignition spark. No storage battery holding down the voltage of the generator, the beneficial feature of operation results that as the engine speeds up, the generator produces current at a higher voltage in order to retain the constancy of the am erage, thus obviating the loss in hotness o spark which would result from the lessened time allowed ,fior building up of magnetic flux within the induction c011.

Having reference to distributer 8 shown in the drawing, it is to be noted that by employing the angle of 2% degrees between distributer arms 31 and 36 and by using the conventional length of arms there will be a distance of not less than inch between the parts of the distributor arm contacts in closest proximity to each other. This distance being the same as that between the distributer contacts which are spaced by 2% degrees, it is seen that jum ing of sparks from arm 31 to 36, or from either arm to a contact other than that designed to be next in order is effectively avoided. This correct operation occurs although the diameter of the'distributer is no greater than'in the usualcommercial single arm type.

If the conventional type of two pole magneto were employed to supply the ignition current it is c ear that the same would have to be operated at four times engine speed in order to produce sparks at a 45 degree interval of crankshaft position with the difiiculties resulting from such high speed of operation apparent to those skilled in the art.

Although the above description'has been applied specifically to a V-typeengine havto be noted that this invention is applicable to engines having any number of cylinders compatible with the V-typeconstruction and that any desired angle may be maintained between the cylinder blocks. However, it is to be noted that there are certain specially beneficial characteristics inherent in the spe. cific construction shown and described.

Itwill thus be seen that there is herein described apparatus in which the several features of this invention are embodied, and

.whichapparatus in its action attains the various objects of the invention and is well suited to meet the requirements of practical use.

As many changes could be made in the above construction, and many apparently widely difi'ere'nt embodiments ofthis invention could be made withoutdeparting from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an eight cylinder V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle to each other of substantially one-half the average angle between explosions, and an ignition system including an induction coil, and a cam for affecting, said induction coil to build up uniform magnetic flux thereinat intervals alternating in the ratio, of oneto.

three.

2. In a V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle to each other of substantially one-half the average angle between explosions, a direct current i ition system including an operating cam aving its operating irregularities spacedfrom each other at alternate'angular intervals having the ratio of one to three, and a complementary irregularity preceding each operating irregularity, said complementary irregularities bein of uniform length.

3. In an eight-cylinder V-type internal combustion engine, in combination, two cylinder blocks arranged at an angle to each other of substantially 45 degrees, and an ignition system including an interrupter cam driven at twice crankshaft speed and having two circuit interruptin eccentricities spaced at substantially 90 egrees.

4. In an eight cylinder V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle of 45 de grees to each other, an ignition system includin an interruptercam, driven at twice cranks aft speed, said cam having two operating irregularities 90 degrees apart and said cam being diametrically symmetrical.

5. In an eight-cylinder V-type internal combustion engine, in combination, two cylinders arranged at an angle of substantially 45 de rees to each other, an ignition system inclu ing a timer, rotatable attwice crankshaft speed, a distributer rotatable at onehalf crankshaft speed, there being two operating irregularities on the cam of said timer, 90'degrees apart, and the distributer contacts being spaced alternately at 22% degrees and 67% degrees.

'6. In an ignition system for internal combustion engines, in combination, a distributer having a center contact, and a concentric conducting ring contact, an electric generator driven from said engine electrically connected with one of said contacts and a chemical source of ignition connected with the other contact, a distributer arm connected with the same contact as said generator, and a second distributer arm retarded by a definite angle behind said first distributer arm and electrically connected with the other said contact.

7. In a V-type airplane engine, in com-. bination, two cylinder-blocks arranged at an angle to each other of substantially one-half the average angle between explosions, an ignition system therefor, including a source of ignition current for starting, an ignition generator driven from said engine for running, a distributer having the angles between successive contacts thereof alternating in magnitude in the ratio of one to three, said distributer having two arms spaced from each. other b an angle-substantially equal to the sma ler angle between said contacts, the more advanced of said arms being connected to said generator, and the more retarded to said starting source.

.8. In an eight-cylinder V-type internal combustion engine, in combination, two 0 1- inder-blocks arranged at an angle of 45 egrees to each other, an ignition system thereor inelugling' a source of ignition current for starti g, an ignition generator driven from said engine for supplying ignition current during running operation, a distributer having an arm in a position corresponding substantially to dea center position an connected with said starting source, a sec ond arm located for substantially 45 degreesadvance, and connected with said generator, said arms being non-adjustable with respect to each other, whereby the angular distance between said arms is equal to the smaller of the angular distances between distributer contacts.

9. In a V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle to each other of substantially one-half the average angle between explosions, an ignition system having two substantiall identical timers, the interrupter; cams t ereofhaving their operating irregularities spaced from each other by ang es alternating in magnltude 1n the ratio of one to three, one 'of said timers bemg angularly advanced with respect to the other.

10." In an eight cylinder V-type internal combustion engine, in combination, two cylinders arranged at an angle of substant ally 45'degrees to each other, an lgnition system including a current generator driven at .twice engine speed, two timers mounted on the axis of said generator, each timer cam 1 having two operating irregularities subst'antiall 90 degrees apart, and being diametrica y symmetrical, the more retarded Tcam being employed during starting,

' and the more advanced during running operation.

.11. In a V-type internal combustion eng ine, in combination, two cylinder-blocks arranged at an an le to each other of substantially one-ha] the average angle between explosions, an ignition system includingtwo timer cams each having itsoperating irregularities spaced from each other at angles alternating in magnitude in the ratio-of three to one, a distributer having its contacts spaced from each other at an:

. gles alternating in magnitude in the ratio of three to one, said timer cams being an larly spaced from each other, and said istfibuter having two rotatable contacts spaced at an angle corresponding to that between the cams.

' 12.;In an eightcylinder V-type internal combustion engine, 1n combination, two,

cylinder-blocks arranged at an angle to each other of substantially degrees, an igmtion system including two substantially identical and coaxial timer cams rotating at twice crankshaft speed, each cam having twofoperating irregularities spaced at an angle of 90 de ees and the cams being angu'larly space with respect to each other for operation 90 de ees a art, a distributer rotatable at one-ha 15 cm .distributer arm, and a second induction,

coil, having its primary interrupted by the more .retar ed cam, and its secondary lead- .ingto the more retarded distributer arm.

13. In an eight cylinder V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle to each other of substantially 45 degrees, an ignition system, including a substantially constant current generator located between woman the blocks, and driven at twice crankshaft speed, two substantially identical timer cams rotatable with the shaft of said generator, each of said cams havin two operating irregularities spaced at 90 egrees from eac other, said cams being diametrically symmetrical, and displaced with respect to each other for operation 90 degrees apart, a distributer mounted on a camshaft of the engine, said distributer having eight contacts alternately spaced fromeach other by 2% de rees and 675; degrees, and two distri uter arms spaced by 2% degrees, the more advanced cam and the more advanced arm being synchronized.

14. In an eight cylinder V-type internal combustion engine, in combination, two cylinder-blocks arranged at an angle to each other of substantially 45 degrees, an ignition system, including asubstantially constant current generator located between the blocks and driven at twice crankshaft speed, three substantially identical timer cams rotatable with the shaft of said generator, each of said cams having two operating irregularities spaced at 9(Ldegrees from each other, said cams being diametrically symmetrical, one of said cams being angularly retarded for operation 90 degrees behind the other two, two substantially identical distributers, one driven from each cam shaft, said distributers having eightcontacts alternately spaced from eachother by 2% degrees and 6 degrees, one of said distributers having two arms spaced by 2% degrees, the more advanced cam being synchronized with the more advanced of the latter two arms, and the other cams being synchronized one with each.of said other arms.

15. In an ignition system for internal combustion engines, in combinatitn, a plurality of ignition circuits and a substantially constant current generator connected with each of said ignition circuits, said circuits consuming the entire .output of said generator as it 1s generated.

16. In a V-type airplane engine, in combination two cylinder blocks arranged at an angle to each other of less than the average an le between explosions, an ignition system or starting including a primary battery as a source of energy, an lgnition system for running operation including an electromagnetic source of energy, said first ignition system havin means for deriving a shower of sparks uring startin said primary battery which shower s all be of uniform duration for the cylinders of both blocks, and means for allowing in said electromagnetic system a period for building up of the magnetic flux preparatory to each s ark, which has the same value for the cy index-s of both blocks.

17. In an ignition system for internal combustion engines, in combination a plu- 3% from rality of ignition circuits including 1 tion coil apparatus, a substantia y constant current generator connected across said I said induction coil apparatus rises .with

inducspeed to maintain the constancy of current for providing a uniform ignition spark at widely varying engine speeds.

In testimony whereof, I have signed my name to this specification this 9th day of November 1917.

LIONEL M. WOOLSON.

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