US2219317A - Ignition system - Google Patents

Description

T. B. HoLLlDAY ET AL 2,219,317

IGNITION SYSTEM Oct. 29, 1940.

Original Filed Feb. 28, 1939 d 52 6214 55 Z0 54 2z s sz 5 s" THEOQRE 5.

Patented Oct. 29, 1940 UNITED STATES PATENT OFFICE IGNITION SYSTEM Theodore B. Holliday and Clarence S. Irvine, Dayton, Ohio Original application February 28, 1939, Serial No.

Divided and this application Novembei 17, 1939, Serial No. 304,962

6 Claims.

(Cl. 12S- 148) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) ly to an ignition system having a transformer associated with each of the cylinders of the engine and a device for checking or testing the operation of the engine, this application being a division of our co-pending application Serial No.- 259,001.

An object of this invention is to provide an ignition system that utilizes one or more transformers or induction coils for each of the cylinders.

Another object of this invention is to provide an ignition system wherein the distributor is located in the low tensionv side of the electrical circuit.

Another object of this invention is to provide an ignition system for an internal combustion engine and the like, which.y ignition system may be tested for defects by merely manipulating the ignition system itself.

Another object of this invention is to'provide an ignition system for a multi-cylinder internal combustion engine wherein the circuit is closed for a sufficient period of time through each transformer to permit a suiliclent voltage impulse to be generated to cause a spark of sufficient duration to discharge the fuel charge within the cylinder. Y

Another object of this invention is to provide an auxiliary test circuit for an ignition system for an internal combustion engine, whereby the defective cylinder may be located while the engine is operating and the circuit leading to the defective cylinder' may be tested while the engine is inoperative. v

Other objects and advantages reside in the construction of parts, the combination thereof and' the mode of operation, as will become more apparent from the following description.

In the drawing,

Fig. 1 discloses a schematic wiring diagram of the preferred embodiment of the ignition system.

Fig. 2 discloses a schematic circuit Wiring diagram of the preferred modication.

In the past, various attempts have been `made to provide a test apparatus for detecting the inoperative cylinder while the engine is running. Two systems have been utilized for making this test. The one method is to shunt the spark gap of each cylinder, so as to ascertain whether or not shunting the spark gap causes additional cylinders to misre. .The other method is to opencircuit the high tension circuit leading to one or more cylinders, .so as to determine in this manner which one of the cylinders is misring.' These i tests have all been made in the high tension portion of the circuit. Due to the fact that it is very desirable to use as short leads as possible and as few leads as possible in the high tension circuit, these methods of testing the circuit have been vfound unsatisfactory, especially in aircraft engines. The corona loss in the high tension circuit is substantially directly proportional to the length of the high tension voltage leads. Usually,

there are excessive corona losses in the high ten- L.

distributor for high voltage is not a simple matter and considerable trouble is experienced with burning of the insulating rotor. This burning of insulation results in charred portions becoming a good conductor of high voltage energy and thereby decreases the voltage impulse that is available for each spark plug. Furthermore, the high voltage wiring, although heavily insulated, is susceptible to the effects of atmospheric moisture and high engine temperatures. These troubles are aggravated by the necessity of locating the high tension cables around and between the cylinders. Due to the heat generatedy by the cylinders, the insulating material has a tendency to fail, become carbonized and lose its properties as an insulating material.

In commercial aircraft the magneto, even though a dual ignition system is used, is still a single source of electrical energy. This is due to the fact that only one drive from the engine is used. In addition thereto, the operation of either half of a dual ignition system is dependent uponi one high voltage coil in the magneto. Failure of this coil will cause inoperation of one-spark plug in each cylinder. When magnetos are used, there is some difficulty in timing the magnetos, especially when used in connection with radial engines. Although the cylinders are equally spaced around the crankcase, the timing of the several cylinders cannot be equally spaced, because a common master rod is used. The deviation from equal timing may be as high as nine degrees (9) in seven (7) cylinder engines. This matter can be corrected by using a multi-lobe cam with the magneto. These Ilobes would be so located on the cam that the timing is always correct; but this solution is rather expensive, complicated, and conducive to trouble.

It is the purpose 0f the present invention to overcome the above objections and to produce a more simple and a less critical assembly. The principle is to conduct direct current to the primary -of a transformer or induction coil which is located on or near each cylinder. The secondary Winding of this transformer will develop a spark when the primary circuit is interrupted, causing a rapid change in the magnetic eld of this secondary winding, resulting in a voltage impulse being generated which is proportional to the change in ilux.

By properly designing the primary winding and the secondary winding of each transformer, a satisfactory voltage impulse maybe produced in the secondary winding by merely utilizing the storage battery voltage or the voltage generated by the conventional generator charging the storage battery. Thus, it is seen that by this system, two sources of electrical energy are available, one from the battery and the other from the generator, so that in the event one fails, the other may be tapped or utilized. Furthermore, by utilizing a transformer which may have two primary windings and two secondary windings, if dual spark plugs are in association with each cylinder, the failure of onecoil or several coils will not result in half or all of the electrical system becoming inoperative. Furthermore, by utilizing transformersadjacent each cylinder or mounted on each cylinder, the high tension leads can be extremely short, thereby reducing corona losses to a minimum.

By utilizing a transformer for each cylinder, the distributor is located in the low tension or primary circuit. This has numerous advantages in that it greatly reduces the hazard caused by high voltage used in the seconary. Furthermore, the distributor may be placed at any convenient location and low tension leads extending from the distributor to the primary terminals of the transformer located at or near the cylinders. The low tension leads, although quite long, do not result in serious corona losses or current leakage, due to the low potential used in the primary circuit. This circuit arrangement permits the use of an auxiliary circuit in the low tension circuit of the ignition system, which auxiliary circuit may be utilized rst, to test for the misring cylinder during operation of the motor, and second, the testing of the circuit leading to the misfiring cylinder when the motor is inoperative.

This has been accomplished by providing a series of shunt circuits that may be` connected across the terminals of 4the distributor, so as to continuously energize the primary winding of any one transformer, thereby interrupting any periodic flow of current or voltage impulses in the secondary circuit. If. for example, a shunt is connected across the distributor so as to shunt the circuit leading to cyinder number three, there will be no spark in .this cylinder. If this is the defective cylinder, the motor will continue to operate as before. Thus, the misfring cyliner is found. If this cylinder is not misfiring prior to the test, it will aggravate the operation of the motor, that is, it will cause another cylinder to misre, thereby indicating that the cylinder under observation is normally functioning. This may be done while the airplane is in flight, or it may be done while testing the engine at the hangar. The switches are preferably located so as to be available to the pilot or the mechanic normal operating conditions.

on board ship, as the case may be. This circuit may further be utilized in testing the engine while it is inoperative, that is, while it is standing still.

Referring to the drawing, the reference charter I0 designates a generator having one terminal grounded and the other terminal connected to an tical excepting for the length of the leads, et

cetera, only one of these circuits has been shown and described.

The fixed terminal or contact 20a. in the distributor is connected to one terminal of each of the primary windings 22 and 24, having the other terminal of each winding connected to a busbar 25 which is grounded through a switch 26 or a switch 28, as the case may be. The primary winding 22 links a secondary winding 30, having one terminal grounded at 30a and the other terminal connected to one terminal of a spark gap 34, the other terminal of the spark gap being grounded at 36. This spark gap is the usual spark gap found in conventional spark plugs.

The winding 24 links a secondary winding 32, having one terminal grounded at 30a and the other terminal connected to one terminal of a spark gap 38, having the other terminal of the spark gap grounded at 40. By this arrangement a dual ignition system is provided for each cylinder, this is, the spark -gap 34 and the spark gap 38 are preferably located Within the same cylinder, so that in theqevent one of the transformers has failed or one of; the spark plugsfails, the other .transformer-and the .other sparkplug will continue to function.

The switches 26 and 28 are always closed under The other contacts yof the distributor are connected to like transformers, one pair of transformers for each of the other cylinders and each of the other contacts of the distributor. If a cylinder is found to misre, it is rather diicult to locate the cylinder, especially in the event a great number of cylinders are used, as for example in a 24 cylinder engine. l

In the embodiment disclosed in Figure 1, the transformers of a particular cylinder may be made inoperative by an auxiliary test circuit which will now be described. The contact 28a is connected through a lead 50 to a switch 52 connected by a lead 54 to the lead I4. By closing the switch 52, current is at all times supplied to the windings 22 and 24. It is a well known electrical phenomenon that a current continuously flowing through a winding will result in a zero current flow in and a zero voltage output from the secondary windings of the transformer, as the E. M. F. generated in the secondary winding of the transformer is proportional to the rate of change of the magnetic flux linking the secondary Winding. A continuously flowing current in a primary winding results in no change of ilux in the secondary winding. By this system any one of the transformers may have the ignition system interrupted by closing the switch corresponding to the transformer in the auxiliary circuits, that is, the switch 52a for the transformer shown, 52h

for the transformer connected tothe contact 20h.

- of the" distributor, et cetera.y When the misring cylinder is located', the engine -may be stopped J and thesamefcircuit utilized fortesting the func- .tioning-of the ignition system for the particular `-frgmcylinrder that* is'misring. First, instead of supwhich-'is'nowfstanding'still,-thebattery 56 is conplying electrical energy from thegenerator I 'fvnectedthroughftheiignitionswitch-@l2 to the lead i' I4; Assuming for the sake l'of argument that the ignition system shown schematicallyis interconnected tothe particular cylinderthat has. been' inisnri'ng,- "by" measuring the" *voltage impulsesl across the-'spark gap 34 1or across :the-spark gap 3B when vthe switchf52iais intermittently opened and closed, 'it may lceudeterminedfwhether or not the circuitis defective. If asunici'ent voltage impulse' gezierated'across the spark gaps, itis reasonable L t'o assume that the de'fectdies either in the dis-2y fitributr'per se' or'fsome mechanical 'portion of ytheV --engi'n' other-'than' the' ignition 'The circuit hownl in Figure tst'ingxtn ignition-isysteinfso as torlocate the misii'ring' cylinder,"1 may also be'utilized to check "i3-'the'transformers"tofdtermiie*whether or not one 'o r mo're transformers may be burned out or ne or Indre plu'gsf be defective or forv` somereason' one or mbreof'theparallel circuits isinperatiVe." This testina-y beperformed While 'the engine is operating. 'B y referring-to Figure lit can readily be seen that oneV termi'nal of each transformer having the primary winding 22 is conn'ectell to; the to'the bus-bar '25. 'By merely opening the. Aswitch 26, `all of the primary wind-lv `ings"22' are openLcircuited, so that no current'A flowsthrough these windings. The charges in the 40..

cylinders are. then Aignited by the yspark gap'y 38jin series with the secondary winding 32 linkinder ormisring cylinders'when'the Wswitch 26'is open. rIiivoneor more cylinders misre, the particular cylinder may be V located by closing in turn the slwil'trcn52'aJ 52h, 52e', et cetera, so 'as to deterv minewhich cylinder is misfiring;

, 'After the vtransformers having' the primary windin 24 have been tested, the switch 26 ma gs y f may result in.a'^fai1ure ofthe. engine to operate be closed and the switch 28 opened.v One terminal of each transformer having the primary winding 24 is vconnected to the bus-bar' 2 5.' By opening I the switch 28, testsmay 'be made to ascertain ,-wheth'er or, notany ofthe circuits including the primary windings 22 and 'thesecondary windings Mare defective. I'f they are, theyr may be located as described above.

This test. has been described as being made while the engineis operating. A similar test may be conducted while the engine is standing s till by; merely measuring the voltage impulses across the several spark gaps.

In the'modication disclosed in Figure 2, an-

other circuitarrangement has been shownrfor testing the ignition system to ascertain which cylinder may be misring. In this circuit the distributor l0 is connected through an ignition switch Sil having one terminal connected to a rotary contact 62, shown schematically, arranged to contact in seriatim the contacts 64a, 64b, 64o, 64d, 64e, and 54j of the distributor 66. The terminals 64a, b, c, d, e, and f are connected to their respective transformers, of which one has been shown, which transformers are identical to those described in connection with the modification disclosed in Figure 1. One primary terminal of the winding 22 and one primary terminal of the.

winding 244 are Aconnected tto, ground through switches a, 12a, 14 and 16, for the particular transformer shown. The other transformers are connected to ground through switches 10b, 12b, 10c, 12o, et cete/ra, and nally, the switches 14 and 1li.` -It is to be noted that one transformer asso- -'ciated with each cylinder is connected through -the switch 14 to ground and the other transformer for veach cylinder is connected through the switchw16 t o ground. In normal operation all of the switches are closed. I

- Two tests may be made by this circuit arrangement. ,Byopening switchy 14, only one' spark plug uwill-be energized for each cylinder, assuming that all f'of "the transformer windings associated there- `with are functioning properly. When the switch 14 is "opened, theitransformer windings 22 and 30 will energize the spark gap 34 in each ofthe cylinders. If all of the Acylinders continue -to fire with 'fthe` switch 14 open, it is evidence that all of the windingsv 22 and 30 are functioning and all of the spark plugs 34 are functioning. If'it develops that" one of the cylinders is misring; or more of tbel cylinders are misring, the missing cylinder may be located byV opening' in turn switches 10a,

' 1lJb, 10c, et cetera, to thereby locate the missing cylinder.` If, for example, cylinder number four is missing, asl evidenced by opening the switch '1nd, then the trouble may be located. After the yall of the primary .windings 24, secondary Windings 32 and the spark plugs forming the spark gaps 38 are functioning. If, for example, it is found'that the third cylinder is now missing, this portionof the system may be further inspected.

By this circuit arrangement it ispossible to locate defectsin the ignition circuit prior to the misring of the cylinder, as one of the spark plugs for the cylinder may be functioning properly without any spark across the other lspark plugs. 'Ihe circuit disclosed in Figure 2 permits testing of the ignition system to locate a defect before it 'that there are two groups of transformers, each group having one transformer" forv each cylinder. Cutting out they transformer" or similar terminologyusedin the claims, is usedto designate the 'open-circuiting or theshunting of-- any of the windings or otherwise causing the transformer `to fail to supply atvoltage impulse to the spark of operation, as disclosed and dened in the appended claims.

Having thus described our invention, we claim: 1. In a dual ignition system for an internal combustion engine having a source of electrical energy, a distributor connected to the source of energy, said distributor having a plurality of out- .let contacts one for each of the cylinders in the engine, the combination including two groups of transformers, each group having one transformer for each cylinder, the primary windings of the transformers for each cylinder being connected to the outlet contacts of the distributor, a pair of bus-bars, a switch for connecting each bus-bar to ground, the other terminal of the primary winding of each transformer in one group being con-v nected to one bus-bar, the primary windings of the transformers in the other group being con nected to the other bus-bar, so that the primary windings of one group may be opened by opening the switch between the bus-bar and ground so as to cause the engine tof'operatenon the portion of:

the ignition system including the other group of transformers, and a pair of spark plugs for each cylinder energized cyclically from the secondary of -the transformers.

2. In a dual ignition system for an internal combustion engine having a vsource of energy. a distributor connected to the source of energy, said distributor having a plurality of outlet contacts one for each of the cylinders in the combustion engine, the combination including 'two groups of spark plugs, two groups of transformers, each group including one transformer for each cylinder, means for interconnecting the pri'- mary windings of the transformers to the cutlet contacts, means for connecting the secondary windings to each a spark plug, one set of windings of each group having one terminal grounded, and a pair of bus-bars connected to ground through each a switch, the other set of windings of one group having one terminalV trical energy through a distributor, the combination including two groups of transformers, each group including one transformer for each cylinder, one terminal of each of the primary windings being connected to the distributor. means for connecting one terminal of each secon winding to its spark plug, one set of windings 'of each group having the other terminal grounded, a pair of bus-bars connected to ground each through a switch, the other set of windings of one group having one terminal connected to one of said bus-bars, the corresponding set of windings of the other group having one terminal con' nected to the other bus-bar, the opening of one switch disconnecting one group of transformers A to ground causing the other group of transformers to cyclicallyenerglze the spark plugs within the engine, and auxiliary testing means for testaaiasi? ing the transformer circuits of said other group for misiiring cylinders when the switch to said one group of. transformers is opened.

4. In a dual ignition system for an internal combustion engine having a pair of spark plugs for each cylinder energized from a source of electrical energy through a distributor, the combination including two groups of transformers, each group including one transformer-for each cylinder, one terminal of each of the primary windings being connected to the distributor, means for connecting one terminal of each secondary winding 'to its spark plug, one set of windings of each vgroup having the other terminal grounded. a pair of bus-bars connected to ground each through a switch, the other set of windings of one group having one terminal connected to one of said bus-bars, the corresponding set of windings of the other group having one' terminal connected to the other bus-bar, the opening of one switch one group oi' transformers@ groundff'fcausingtthe other group of transformers to cyclically energize the spark plugs within the engine, and auxiliary testing means including shunt circuits connected across the distributor for supplying a continuous current to the portion of the circuit imder test.

5. In a dual ignition system for an internal combustion engine having a pair of spark plugs for each cylinder energized from a source of electrical energy through a distributor, the combination including two groups of transformers, each group including one transformer for each cylinder, one terminal of each of'the primary windings being connected to the distributor, means for connecting one terminal of each secondary winding to its spark plug, one set of windings of each group having the other terminal grounded, a pair of bus-bars connected to ground each through a switch, the other set of windings of one group having one terminal connected to one of said bus-bars, the corresponding set of windings of the other group having one Aterminal connected to the other bus-bar,

.the opening of one switch disconnecting one group of transformers to. ground causing the other group of transformers to cyclically energize the spark plugs within the engine, and switching means including one switch in one of the windings of each of the transformers to open-circuit a transformer in the other group.

6. In a dual ignition system for multi-cylinder internal combustion engines having a source of electrical energy connected to a distributor having a plurality of outlet contacts energized cyclically from a source of electrical energy, the combination including two spark plugs for each cylinder, two groups of transformers, each group including one transformer for each cylinder,

the primary windings being connected to the outlet contacts in the distributor, the secondary windings being connected to the spark plugs of the engine so as to 'electrically energize the cyl- .Y

inders in parallel, means for cutting out one group of transformers, and means for cutting out any one transformer of the other group of transformera.

THEODOR-l B. HOLLIDAY. CLARENCE S.

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