US1589489A - Electric ignition system - Google Patents

Description

June 22 1926.

H. C. SNOOK ELECTRIC IGNITION SYSTEM- Fiied Oct. 15 1920 2 Sheets-Sheet 1 IIIHIH llmm Wye/77%;: 5 Homer 675/7005. J W A/fy;

June 22 ,1926. 1,589,489

- H. C. SNOOK ELECTRIC IGNITION SYSTEM Filed Oct. 15 1920 2 Sheets-Sheet 2 /nve/7f0/' Homer C. dnook. by WM.

Patented June 22', 1926.

UNITED STATES PA-TENT OFFICE.

HOMER CLYDE SNOOK, OF SOUTH ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN- ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF N EW YORK.

ELECTRIC IGNITION SYSTEM.

This invention relates to an electric ignition system using high frequency current to ignite explosive charges and is especially to the high frequency current generating.

means.

' The fact that a high frequency current discharge across the ignition gap of a spark plug possesses the peculiar property of not being materially affected by. defects in the insulation of the plug and that a plug may be fouled, even to the extent of being short oircuited by loop of conductive material. without stopping the spark was, perhaps, first pointed out by Sir Oliver Lodge.

Ignition systems utilizing high frequency current have been devised but they generally involve the use of an induction coil, the secondary Winding of which'is associated wlth a capacity to constitute an oscillatory circuit having a spark gap .in air as a discharge element for said circuit;-the terminals of the spark plug operating as a secondary discharger therefor. The disadvantage of such systems is that the high frequency current source is of low electric efficiency, unreliable and non-controllable, and hence, while demanding considerable care and attention" on the part of the operator, are found to be of no practical value.

The primary object of this invention 1sto "devise an ignition system employing high frequency current which is free from these defects and eminently satisfactory from a practical point of view.

Another object isithe production of high tension high frequency current from a low voltage source of current.

. A further object is the provision of a source of high frequency current which does not involve discharge elements in air,whereby contact terminals of highly infusible ma terial such platinum, tungsten, etc, Which are essential to the induction coil lgnition systems of today, are eliminated.

Still another object is to prov'de a variable frequency source of high frequency current for ignition purposes. I

A still further object is the provision of means whereby a love voltage source of vibratory or alternating current may be controlled-to supply selected portions of the positive current wave .to the plate circuit of an electronic, tube.

These objects and others which will ap pear as the description of the invention proceeds may .beobtained by the arrangement herein set forth which discloses one method of accomplishing this result.

Briefly, this invention comprises a space discharge device as a source of high frequency current adapted to be energized by a low tension current source, and a circuit for transmitting the high frequency impulses to the ignition device or devices, this circuit being in resonance with the tuned circuit which, as is well known, is associated with the oscillator to determinethe frequency of the oscillations produced.

When used to supply ignition current to a multiple cylinder engine, the operation of the oscillator is .controlled by a make and break device or interrupter to supply high frequency current when the spark circuit is completed and to prevent the generation of oscillations when this circuitis opened; a

distributor being used to connect the spark plugs in proper sequence and at the proper time periods, relatively to the interrupter, to make and break said spark circuit.-

Like reference characters "indicate like parts in all the figures of the drawings in In the arrangement shown in Fig. 1. an-

oscillation generator of the type disclosed control circuits f.

' back to the input circuit.

- current.

used as a source of high frequency current, by way of example. This oscillation generator comprises a space discharge device 1 having an input circuit extending from a hot filament 2, to and through an adjustable inductance coil 6 to an impedance controlling. element 4:. An output circuit connected between said filament and an anode 3 has an adjustable inductance coil 5 included therein, The coils 5 and 6 having the adjustable condenser 7 connected across their terminals constitute a closed oscillatory circuit. The natural period, of the oscillatory circuit may be varied to control the frequency'of thebscillations produced therein. Increments of I oscillating energy are. fed The battery 8 supplies heating current to the filament 2 and the batter 9 supplies plate current to the discharge evic'e.

As described in the above mentioned patent, oscillations are set up in the tuned circuit, by means of the coil 10, designed and associated with the oscillatory circuit. 5, 6 and 7 in a manner similar to the secondary of an Oudin resonator. By means of this arrangement high potential impulses of predetermined frequency are transmitted to the spark device 11 to which its outer terminal is connected, the other terminal of the spark device being grounded. The oscillatory circuit is connected to the frame of the engine and is thus grounded at 12 to provide a return path for the high frequency Instead of grounding the secondary terminal of the spark device, a conductor, indicated by the dotted line 13, may

be used to connect it to the oscillatory cir- Y cuit. A polarizing battery 14 may be used to supply a negative'potential to the grid l, thereby maintaining said grid negative relatively to the cathode. The spark device may be mounted in the head of a single cylinder engine to ignite the charge, therein, may be used to ignite a mine, a blasting charge 'or for any other similar purpose.

Referring to Fig. 2, there is shown an electric system for an automobile in which current, generated in a low tension winding .20 mounted on the rotor 21 of a magneto or motor starting and lighting dynamo of the system, flows through the primary of the transformer 15 thereby setting up current in the secondary of said transformer,

. which secondary is connected in the output 'circuit of the discharge device to supplyplate current thereto. Thus, the low volt- .age winding 1s used in this arrangement as a substitute for the battery 9 of Fig. 1.

Plate current flows from one terminal of the secondary winding of the transformer 15 through th coil 5 .to the filament'2, thence to the/plate 3* and back to the other incense terminal of saidwinding. The flow of this current sets up oscillatory current in the tuned circuit 5, 6 and 7, increments of which, as is fully set forth in the above mentioned patent, are fed back to the grid to control the operation of the discharge device. These oscillations traverse the'conductor 32 and the connection including the condenser 16;

which constitutes a low impedance path for discharge device is utilized to determine or select the intervals during which energy is applied to the oscillatory circuit and, as a consequence, high frequency impulses are transmitted to the spark circuit.

Connected in parallel to the condenser 16 is a circuit containing a battery 17 and a make and break device-18. The battery is designed to apply a negative potential to the grid 4, when the circuit is completed by the make and break device, of sufficient, magnitude to suppress or so reduce the plate currentthat thetube is inoperative. Thus, when the battery circuit 1718 is completed'no current is supplied to the oscillatory circuit, but when it is open the discharge device operates to supply impulses to the oscillator circuit."

1Z1 parallel with the condenser 16 is a second path including a high resistance 19' which serves as a leakage path to prevent the tendency of a negative charge to accumulate on the grid 4 which, if not dissipated, would ultimately block the discharge device. The resistance 19 is so large that it does not conduct appreciable current from the battery 17 when the interrupter 18 is closed or interfere with the flow of the oscillations through the parallel condenser path when the movable arm 22 of a rotary distributor which by successive engagement with the contacts '23 completes the circuit of the spark plugs 27 associated with the engine 31, whereby high frequency impulses are transmitted in proper sequence to the cylinders of said engine, to ignite the explosive high tension distributor 22-23, the leads to the spark plugs 27 and the return path to the tuned circuit 5, 6 and 7 constitutes the circuit for transmitting the high frequency impulses to theignition device or devices which, as is hereinbefore'stated isrin resonance with the tuned circuit 5, 6 and 7.

The make or break device merely involves a fixed contact periodically engaged for a definite interval by a movable contactwhose motion may be controlled by the crank shaft of the engine and may therefore be of any suitable design.

Ignition sparking will occur at the proper time at the proper spark plug when the magneto, the make and break "device, and distributor arm are driven by a co'mmonxdriving mechanism designed to maintain such.

time relation between them, in the performance of their functions, that a positive impulse of sufficient voltage value is supplied by themagneto to the plate circuit of the discharge device to set up oscillations, the interrupter is in open circuit position, and

the distributor is in engagement with a seengages said contacts. Hence for an inter-.

val of time, slightly greater than the oscillation producing period, the spark circuit is completed, and consequently disruptive discharges across the distributor contacts is avoided;

That the Bosch high tension magneto may be readily modified to adapt it to use with an oscillator including an electron discharge -device,-is shown in Fig. 3, wherein the rotor 33 of such a magneto is illustrated. The

high tension winding 34 is open circuited as indicated at 35. One terminal of the low tension winding 36 is "disconnected from ground and connected to the slip ring 37, a

rush in engagement with said ring being connected to the primary-"of the transformer 15, the other terminal of said primary being directly connected to the other end of the low tension winding. The secondary of the transformer is adapted to be connected to the oscillator shownin Fig. 2 with which arrangement this adaptation is designed to be used.

Another arrangement of the ignition system is shown in Fig. 4. In this system, a divided battery is utilized as a source of ower. One portion 17 supplies the blocking potentialto the 4 through an interrupter 39, a'second portion 8 supplies heating current to the filament 2, While a third portion 38 is .connected to the plate circuit which-extends from the cathode 2 to one terminal of the battery subdivision 38 andfrom its other terminal through atuned circuit consisting of an adjustable winding 5 and an adjustable condenser 7 to the plate 3. Oscillations of a definite frequency, determincd by the constants of the tuned circuit, are thereby produced in this latter circuit;.increments of which, derived from aortion 40 of the coil 5,'are fed back to the impedance control element 4 through a low impedance path including the condenser 16. As in Fig. 2, a high resistance 19 is connected in shunt to the condenser for thepurpose hereinbefore set forth with reference to said last-mentioned figure.

Inductively related to the winding secondary windin 41 which may be designed to havesutti cient distributed capacity 5isa to permit of its being tuned by adjustment to the frequency of the oscillatory c rcuit associated with the tube, or it may be the secondary of an oscillation transformer having an ad ustable capacity to effect tuning, as

indicated by the dotted line connection 42 shown in this figure. In this modification one terminal of the secondary winding is connected to the hightension distributor arm 22, the other end of said secondary being connected to the engine frame at 43 to constitute a, return path for the high frequency current. The stationary contacts of the distributor are connected to the spark plugs in proper order.

The method of operation of this system is similar to that of the construction shown in Fig. 2. Any other form of oscillation asfor example that described 1n generator, U; S. Patent 1,472,470, October 30, 1923, to R. V. L./Hartley, may also be used as a source of high frequency current;

In the system shown in Fig. 5, energy is supplicd'to heat the filament 2 by means of the transformer 44 and to thegrid Q through the transformer 45, whose primary is reversely connected to the magneto, and also to the plate 4 by the transformer 15; The transformers 44 and 45 are designed respectively to maintain the filament heated to the desired temperature and to apply po, tential of the desired magnitude to the grid at the desired intervals in the cycle of operation of the magneto.

In this showing, the discharge device is blocked during the negative wave period of the magneto by the application of a negative potential-tothe plate of the discharge device and during desired portions of the positive wave period of'said magneto by the application of a negative voltage, through the transformer 45 to the grid 3, under the control of the make and break device 18.-

-flow therein to a negligible quantity when the grid is positive relative to the filament.

The resistance 46 may be dispensed with if the grid circuit is open during the positive wave period of the magneto. In order to effect this. there is illustrated in Fig. 6

a make and break device provided with a pair of short segmental contacts 47 and 48 in place of the longer single contacts shown in the preceding figures. Thus, during the time when a positive wave is being supplied [to the plate circuit of the discharge device, first the grid circuit is completed through one of these contacts 47 after which this circuit is opened for an interval, during which oscillations are produced and high frequency current is supplied to the, spark circuit. This interval is then followed by another contact interval, the contact arm 18 being in engagement with 48 to impress a negative potential upon the grid and prevent oscillation production; .A non-contact period then follows, but, as a negative potential is supplied to the plate element of the dischargedevice, the flow of space current is suppressed and generation of oscillations is thereby prevented. This cycle of operations is continuously repeated.

Under certain conditions an arrangement of the type shown in Figure 5, with or without the interrupter of Figure 6 to control oscillation production, will be preferable to those illustrated in Figures 2 and 4. In this arrangement the magneto, interrupter and distributor arms will be driven in proper time relation by a common driving mechanism similar to that heretofore described and the discharge device and its related circuits, just described, will be associated with either the Oudinresonator of Figure 2, or g the transformer of Fig. 4 and their related spark circuits. The dotted line A-A serves to indicate the fact that said additional elements must be used to complete the system and the. plane of connection in these figures;

\Vhile separate transformers have been shown to suppl the grid, filament and plate circuits, it is *0 vious that other methods of deriving the, desired energy may be used. For instance, a plurality of secondary windings associated with, or a tapped secondary inductively related to, the primarywinding of the transformer 15 may be used.-

In Figs. 2, 4, 5 and 6, no attempt has-been made to indicate accurately the open and closed circuit periods of the interrupter and distributor, since in said figures the showing is merely schematicof one of the wellknown forms of switching devices which may be used for the purpose desired. It will be suficient to state that, in the case of the former, the circuit from the source of blocking potential should be open for brief intervals relatively to the time period of one complete generating cycle of the magneto and cyclically with the sparking periods,

and, in the case of the latter, the spark 011- cuit should be closed for substantially similiar periods. By using the well-known bayonet socket a spare electron tube may be substituted for one that-is worn out, hence the matter of renewals becomes simpler and less troublesome than the renewal of cont acts employed in ignition systems heretofore known.

As stated above, the discharge device may be rendered inoperative or blocked by the application to its grid or plate of an electrostatic charge of definite voltage negative to the filament, The current fioW in the grid circuit will be negligible under the conditions hereinbefore described. Moreover, as the circuit connecting the grid and the source of potential used for blocking purposes is practically a short-circuit, hence without inductance, there will be uniform potential conditions throughout this circuitwhen the discharge device is inoperative. Under-the most adverse potential conditions, during its operating periods, the

voltage applied to the grid will not be materially different from that supplied .by the blocking source. Therefore, since the con trol of the grid does not involve energy or current, the circuit connecting the blocking source to the grid being without inductance and a practically uniform po'tentialcondition existing between source and grid, it will be evident that the grid circuit may be made and broken by the interrupterwithout arcing at its terminals. 3

Again, as the spark circuit is adapted to be completed ,just prior to the time when the discharge becomes operative and is maintained in a closed circuit condition for a brief interval after the termination of the oscillation production period, no destructive discharges will take place across the ter minals of the distributor.- V y By changing the adjustment of the con- IID' denser, windings of the resonator,'or both,

the periodicity 'of the oscillations generated may be varied. This is important since by this simple adjustment a bet" spark is always assured regardlessof the conditions at the terminals of thesparlgiplug or plugs, due

either to differences in design, imperfections memes that this invention is not to be construed as trol element to block the device, a spark cirlimited either to such use or the means herein set forth, but includes all such modifications and uses as fall within the scope of the appended claims. 7

VVhat' is claimed is:

1; An' ignition system comprising an oscillation generator including an electron dis-.

charge device and means to determine the frequency of, the oscillations produced, a source of low tension alternating current supply for said generator, means to render the generator inoperative at selected intervals and a spark circuit in resonance with" said frequency determining means.

2. A- system comprising an oscillation generator including an electron discharge device and meansto determine the fre quency of the oscillations generated, a

source of low voltage alternating current- .supply for the generator, means to prevent energization of the device for time intervals greater than, but including the time during which negative Waves are supplied by said source, and a circuit in resonance with -said frequency determining means. I

' 3. An ignition system'comprising an oscill'ation generator including an electron discharge device and means to determine the frequency of the oscillations produced, a source of low voltage alternating current supply for the generator, means controlling the device to render it inoperative when the low voltage source supplies negative curcil'lation generator including an electron disv it rent Waves, and a spark circuit tuned to the frequency of said. frequency determining means. v I i 4. An ignition system comprisingan oscharge device and the primary of a resonator as a means to determine the frequency of the oscillations generated, sparking means,'the resonator secondary including 'erator, and means 5. An-ignition system for a multiple cylinder engine comprising an oscillation generator including an electron discharge device, an lmpedance control element for the device, means lntermittentlyi to apply a cuit coupledto the generator and means to connect the circuit to the spark plugs in proper sequence, and to each plug substantially during a non-blocked period of the device. y

7. An ignition system for a multiple cylinder engine comprising an oscillation generator including an electron discharge device and means to determine the frequencv of the oscillations produced, an impedance control element for the device, a source of negative potential adapted to be connected cyclically to the control element during definite time intervals, a spark circuit in resonance with said frequency determining means, and means to connect the c1rcu1t to the spark plugs in proper sequence and to each plug substantially during an interval when the source of negative potential is disconnected from the impedance control element.

8. An ignition system comprising a spark gap, an oscillation generator including an electron discharge device, and an Oudin resonator, the primary circuitof the resona tor operatm as a means to determine the frequency 0 theoscillations produced, and

the spark gap being included in the secondary circuit of the resonator.

.9. An ignition system for a multiple cylinder engine comprising an oscillation genera-tor including an electron discharge de vice and frequency determining means which also functions as'the primary of an Oudin. resonator, an impedance control element for the device, a potential source adapted to be connected to the impedance control element to block the device, and a spark circuit, the

secondary of said resonator constituting said spark circuit. and having means to connect t e circuit to the spark plugs in proper sequence and to each plug during a nonblocked period of the device.

10. A method of operating an electric discharge device. having input and output circuits associated therewith comprising supplying an alternating current to the output blocking potential to the impedance control element, a spark circuit coupled to the gento connect said circuit to the spark plugs .in proper sequence and to each plug substantially during a non device,' a source of negative potential adapt- ,edto be connected intermittently to the concircuit of the device, and applying a potential to theinput circuit to render the device inoperative at selected intervals. I

11. A method of operating an electric discharge device having a cathode, an anode and an impedancecontrol element which comprises supplying a low voltage alternating current to t e plate circuit thereof, and applying a potentialto the impedance control' element to render the device inoperative at predetermined intervals.

12. A method of operating a thermionic device having a. cathode, an anode and an impedance control element which comprises supplying a low voltage alternating current to the anode circuit thereof and recurrently applying a blocking potential to the impedance control element for a period greater than a half cycle ot said low voltage alternating current,

13. Means for operating an electron discharge device comprising means to supply alternating current to the output circuit of the device, and means to supply the input circuit of the device With a potential adapted torender the device inoperative at se'- lected intervals.

14%. Means for operating an electron discharge devicehaving a cathode, an anode and an impedance control element comprising a low tension alternating current source connected to the cathode and anode, and means to apply a potential to the impedance control element to render the device inopera- .tive at selected intervals.

15. An ignition system for a multiple cylinder engine comprising an oscillation generator including an electron discharge device and means to determine the frequency 1 of the oscillations produced, an impedance .control element for the device, means to apply intermittently a blocking potential to theimpedance control element, a spark circuitlin resonance with'the frequency deter- -rnining means, *and means to connect said circuit to the spark plugs in proper sequence and to each plug substantially during a nonblocked period of the device.

16. Means for operating an oscillator com- ,prising an electron discharge device having an input circuit, an output circuit, a coupling connecting said circuits, a low voltage alternating current source of supply for the output circuit, and means for neutraliz- .ing the regenerative effect due to said coupling during predetermined intervals.

17. An ignition system for a multiple cylinder engine comprising a generator of sustained oscillations including means selectively to" determine the frequency of the oscillations produced, means to render the generator inoperative at selected intervals, a spark circuit connected to and in resonance wlth the frequency determining means, and

;means to connect the spark circuit to-the spark plugs in proper sequence and to each "substantially in-synchronism with the gen- .wlectively the frequency of the oscillations produced, means to limit cyclically the gennssaeee eration of oscillations to definite time intervals, a spark circuit in resonance with the frequency determining means, and means to connect said circuit to the spark plugs in succession substantially in synchronism with the generating intervals. l

20. Anignition system for internal com-' bustion engines, comprising a plurality of spark plug circuits-forming part of the igni tion circuit, electric discharge means associated with said spark plug circuits, said discharge means having a plurality of electrodes, and means for controlling the flow of electrical energy between the electrodes of said device and to a plug circuit for practically the duration of the ignition interval.

21. An ignition system for internal combustion engines, comprising-a plurality of spark plug circuits forming part of the ignition circuits, electric discharge means associated with said spark plug circuits, said discharge means having a plurality of electrodes, means for controlling the How of electrical energy between the electrodes of said discharge means and to a plug circuit for practically the duration of the ignition interval, and connections between spark plug circuit and the circuit of the discharge means whereby the ignition current is caused to flow through the plug circuit.

22. An ignition distributing system for internal combustion engines comprising a plurality of spark plug circuits forming part of the ignition system, electric discharge means associated with said plug circuits, said discharge means having a plurality of electrodes, and means for controlling the flow of space current between the electrodes of said discharge means so that iguition current is supplied to a plug circuit for practically the duration of-the ignition interval.

'23. An ignition distributing system for internal combustion engines. comprising a plurality of-spark plug circuits, electric discharge means provided with a plurality of electrodes and associated with said plug cir' cuits, means associated with each plug circuit and the circuits; of the discharge means for controlling the flow of space current through the discharge means whereby ignition current is supplied to a plug circuit during practically the duration of an ignition interval.

24:. An-ignition distributing system for internal combustion engines. comprising a plurality of spark plug circuits, electric discharge means provided with a plurality of electrodes and associated with said, plug circuits, means associated with the plug circuits and the circuits of the discharge means for controlling the flow of space-current through the discharge means whereby ignition-current is supplied to theplug circuits in proper sequence and to each plug circuit for practically the duration of an ignition interval.

25. An ignition distributing system for internal combustion engines, comprising a plurality of spark'plug circuits, electric discharge means provided with a plurality of electrodes and associated with sa1d plug circuits, means associated with each plug oilfcuit and the circuits of the discharge means for preventing and permitting the flow of space current through the discharge meansto control the discharge of a spark.

26. An ignition distributing system for internal combustion engines, comprising a plurality of spark plug circuits, each including a spark gap, electric discharge means provided with a plurality of electrodes and associated with said spark ,circuits, means associated with said spark circuits and the circuits of said discharge means for preventing and permitting the flow of space current through the discharge means to control the discharge of sparks across said gaps in proper sequence and across each gap during the proper interval.

27. In an ignition distributing system for internal combustion engines, spark circuits including plugs each having sparking elec trodes, electric discharge means provided with a plurality of electrodes associated with said plug circuits, means associated with the circuits of the discharge means and each plug circuit for permitting and preventing the flow of'space current between the electrodes of said discharge means to control the passage of current across the sparking electrodes.

28; In an ignition distributing system for internal combustion engines, spark circuits including plugs each having sparking electrodes, electric discharge means provided with a plurality of electrodes associated with said plug circuits, means associated with the circuits of the discharge means and each plug circuit for permitting-and preventing the flow of space current between the electrodes of said discharge means to control the passage of current through the plug circuits in proper sequence and across the sparking electrodes of each plug at selected intervals.

29-. An ignition distributing system for internal combustion engines comprising a plurality of spark plug circuits forming part of the ignition circuits, electric discharge means having an anode, a cathode and a grid, circuits including said discharge means. means for associating the circuits of said discharge means wlth sa1d plug circuits, and means for rendering the discharge .means operative during selected intervals.

30. An ignition distributing system for internal combustion engines comprlsing a plurality of spark plug circuits, forming part means,

of the ignition circuits, electric discharge circuits including said discharge means for associating the circuits of said discharge means with said plug circuits, and means for controlling the actid n of said grid to preventand permit the flow of space current between the anode and cathode at selected intervals.

31. An ignition distributing system for internal combustion engines comprising a plurality of spark plug circuits, electric discharge means having control means between anode and cathode means, circuits including said discharge means as well as plug circuits and means adapted to control the action of said control means.

32. An ignition distributing system for internal combustion engines comprising a plurality of spark plug circuits, electric discharge means and circuits containing said discharge means, connections between said plug circuits and the circuits of said discharge means, said discharge means having control means between anode and cathode means, and means for controlling the time of ignition by differing variations of potentials applied to the control'means.

grid,

In an ignition distributing system for I internal combustion engines, an ignition circuit, a thermionic tube for controlling said ignition circuit and a control circuit for said thermionic tube independent of said ignition circuit.

34. In an ignition distributing system for internal combustion engines, a plurality of ignition devices, energizing circuits for said ignition devices and distribution control means for said energizing circuits exclusive of said energizing circuits.

35. An ignition distributing system for internal combustion engines comprising a plurality of ignition devices and circuits therefor, thermionic discharge means for said ignition circuits and control means including a controller for said discharge means and distributing circuits. 7

36. An ignition distributing system for internal combustio engines comprlsing a plurality of ignition circuits, a source of plug substantially period ofthe device;

the impedance control element of said device, and means to connect said circuit to the spark plugs in proper sequenceand to each during a non-blocked 1 so controlling said tube that its oscillations are available practically only during the ignition interval and means utilizing said oscillations for producing the necessary sparking voltage.

,40. An ignition system for internal COl'lll bustion enginesfcomprising in combination, a sparking plug, a thermionic triode tube adapted to generate electric oscillations, means for so controlling the potential of the tube control element that the thermionic current is allowed to pass only during the ignition interval and means utilizing said oscillations for producing the necessary sparking voltage.

41. An ignition system for internal combustion engines, comprising in combination, asparking plugya thermionic triode tube and generator circuit therefor arranged to generate electric oscillations, a commutator comprising a wipe contact and a series of com 'ilemeutary contacts connected to the tube control element and to the generator circuit in such a way that only during the ignition interval a potential is applied to the control element ofthotube allowing the thermionic current to pass, and means utilizing said oscillations for producing the necessary sparking voltage substantially as described.

42. An ignition system for internal combustion engines, comprising in combination, a sparking plug orv plugs, a thermionic tube adapted to generate electric oscillations, means for so controlling said tube that its oscillations are available practically only during the ignition intervals, means utilizing said oscillations for producing the necessary sparking voltage, and a distributor adapted to transmit the sparking voltage to said sparking plug or plugs.

43. An ignition system for internal combustion engines, comprising in combination, a sparking plug or plugs, a thermionic triode tube and generator circuit therefor arranged to generate electric oscillations, means for so controlling the potential of thetube con,-

aasaese trol element that the thermionic current is allowed to pass only during the ignition intervals, means utilizing said oscillations for producing the necessary sparking voltage, and a distributor adapted to transmit the sparking voltage to said sparking plug -mit the spa-rkingvoltage to said sparking plug or plugs, substantially as described.

45. An ignition system comprising ignition spark terminals, an air tight vessel containing electrodes associated with suitable circuits for controlling the generation of' oscillatory current, means connecting said vessel and said terminals for providing sparks under the influence of said current, and a single source of energy supply for the syslem,'said source supplying energizing polentialsfto said electrodes.

'40. An ignition system comprising spark terminals, an air tight vessel enclosing a space discharge path associated with suitnblc circuits, means connecting said circuits to said spark terminals,'and a source for supplying energy to said path for controlling the energy in said path to cause the generation ol oscillatory current and for controlling the supply of oscillatory current to said spark terminals.

47. An ignition system comprising spark terminals, an air tight vessel enclosing a space discharge path associated With suitable circuits, means :for connecting said circuits to said spark terminals, and a source for supplying energy to said path for controlling the. energy in said path to cause the production of oscillatory current and for determining a definite interval durirfg which oscillatory current is supplied to said spark terminals.

48. An ignition system comprising a plurality of ignition devices, an air tight vessel enclosing a space discharge path associated with suitable circuits, means for connecting said circuits to said ignition devices successively, and a source for supplyingenorgy to saidspace path, for controlling the energy in said path to cause the generation said ignition devices in sequence.

49. An ignition system comprising a plurality of spark plugs, an air tight vessel containing electrodes associated with suitable circuits for controlling the generation of oscillatory current, means for cyclically connecting said circuits to said spark plugs, and a single source of energy for the sys' tem, said source supplying energizing potentials to said electrodes whereby oscillameans for connecting said oscillator to said terminals, and a single source for supplying energy to said oscillator.

52. An ignition system comprising a pluralit of ignition devices, a space discharge oscillator, means for connecting said oscillator to said devices in succession, and a single source for energizing and controlling said oscillator to generate oscillatory current only when said oscillator is connected to said devices.

53. An ignition system comprising ignition spark terminals, and air tight vessel containing electrodes supplied with energy and associated with suitable circuits to control the generation of oscillatory current,

and means for connecting said circuits and said terminals for providing sparks under the influence of said current.

54. In an ignition distributing system for internal combustion engines, an ignition cir cuit, a tube including an electron emitter and a circuit associated with said tube to control the supply of current to said ignition circuit.

55. An ignition system comprising spark. terminals, an air tight vessel enclosing a space discharge path supplied with energy and associated with suitable circuits, means for connecting said circuits to said spark terminals, and means for limiting the flow of energy in said path to substantially the period when said circuits and said terminals are connected.

56. An ignition system for internal combustion engines, comprising in combination, a sparking plug or plugs, a thermionic tube adapted to generate electric oscillations, and means utilizing said oscillations for producing the necessary sparking voltage.

57. An ignition system for internal combustion engines, comprising in combination, a sparking plug or plugs, a thermionic tube adapted to generate electric sustained oscillations, means utilizing said oscillations for producing the necessary sparking voltage, and a distributor adapted to transmit the sparking voltage to said sparking plug or plugs at the proper ignition intervals, as set forth.

58. An ignition system for internal combustion engines, comprising in combination, a sparking plug or plugs, a-thermionic triode tube and generator. circuit therefor arranged to generate electric oscillations, a commutator connected to the tube control element and to the generator circuit in such a way that only during the ignition intervals. a potential is applied to the control element allowing the thermionic current to pass, means utilizing said oscillations for producing the necessary sparking voltage, and a distributor adapted to transmit the sparking voltage to said sparking plug or plugs and having contact members, the duration of engagement of which is longer than that between said wipe contact and the fixed contact of said control commutator, substantially as described.

59. An ignition system for internal combustion engines, comprising in combination, a sparking plug or plugs, means for generating sustained high frequency electric oscillations, and means utilizing said oscillations for producing the necessary sparking voltage.

In witness whereof, I hereunto subscribe my name this 9th day of October A. D.,

1920. H. CLYDE SNOOK.

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