US2184315A - Ignition system for internal combustion engines - Google Patents

Description

e- PETERS HAL 2,184,315

IGNITION SYSTEI FOR INTERNAL COIBUSTION ENGINES Filed Aug. 11, 1939 ifivzmoras M51. V/LLE F. PE rem GEO GE E'BLACKBURN AT 5 RNEY Patented Dec.26,1939 T 2,184,315

UNITED STATES PATENT OFFICE rom'rron srs'rsm 'roa nv'rsnmr. COMBUS- nos enemas Melville F. Peters, Beltsvilie, Md., and George 1!.

Blackburn, Washington, D. C.

Application August 11, 1939, Serial No. 289,814 9 Claims. (Cl. 123-448) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates generally to ignition and these interconnected terminals also connect systems for internal combustion engines, and to both movable breaker point contacts 8 and particularly to ignition systems suitable for mul- It. The remaining terminal of primary or low ti-cylinder internal combustion engines operat- ,.voltasawiading t connects to fixed breaker point 5 ing at high speeds. contact and the remaining terminal of prl- 5 An object of this invention is to provide an ary winding 8 connects to fixed breaker point improved ignition system for internal combustion contact l2. The circuit at breaker point contacts engines that is capable of supplying a spark 9 and H, as well as the circuit at breaker point of undiminished voltage to multi-cylinder encontacts I0 and II, are normally closed by spring 0 gines operating at high speeds. action. A rotatable engine-driven cam l3 oper- 10 Another object of this invention is to provide ates to break the circuitat these contacts in acan improved ignition system for internal comcordance with the timing of the engine. Secondbustion engines that utilizes a substantially unary or high voltage winding ll of transformer interrupted flow of current from the supply gen- 6 is inductively coupled to both primary windings erator and a unidirectional current flow in the 5 and 8, one terminal l5 of winding M being con- 1 primary circuits of'the induction coil or transnected to the engine distributor (not shown), .iormer. the other terminal It being connected to ground.

Another object of this invention is to provide The distributor is of conventional type and selecan improved ignition system for internal comtively energizes a number of conventional spark a0 bustion engines in which 'thegenerator is at no plugs (not shown) in a manner well known to the time short circuited except by a capacitor, makart. Either the positive or the negative terminal ing the. use of a current limiting resistor unnecof the generator may be connected to ground essary. without affecting the operation of the system.

Another object of this invention is to provide] Capacitors 4 and I are preferably, though not as an improved ignition system for internal comnecessarily, of equal capacity. Secondary windas bustion engines in which the primary circuit ing I4 is wound with many times the number 0! breaker points are not subject to contact deterturns of either primary winding 5 or i, such that iorating arcs when the primary circuit is broken. the voltage induced in the secondary winding will A further object of this invention is to provide be suflicient to jump the spark plug gap within 80 an improved ignition system for internal comthe cylinders of the engine. Preferably, though so bustion engines which employs the substantially not necessarily, primary windings 5 and l are simultaneous charge of one capacitor and disso disposedin inductive relationship with secondcharge oi another capacitor in the production arywinding l4 and are wound with such a numof the high voltage secondary voltage. ber of turns as to induce substantially equal volt- 85 Our invention will be explained in connection ages in winding ll. v I,

I with the accompanying drawing, which is 9. dia- 'In operation, assuming both capacitors initially grammatic sketch of an ignition system incordischarged, with the breaker point contacts in porating our invention in its preferred form. the position shown in the figure, capacitor 1 is Referring to the drawing, the positive supply charged through primary winding 5 and breaker 40 line 2 from a conventional engine driven generpoint contacts'Sand ll substantially to the ter- 44 ator or other direct current source of electrical minal voltage of the generator or other charging energy (not shown) connects to one terminal of source. As cam l3 rotates in the direction incapacitor l and also to one terminal of one pridicated, the circuit at breaker point contacts 9 mary or low voltage winding 5 of iron core stepand H is broken and immediately thereafter 4-! up transformer or induction c0116. The negative the circuit at breaker point contacts l0 and l2 5 supply line 3 from the generator connects to one closes, permitting capacitor 1 to discharge terminal of capacitor I and also to one terminal through primary winding 8. Substantially siot the other primary winding 8 of transformer multaneously with this discharge, capacitor 4 is 6. A storage capacitor 2' is preferably connectcharged through breaker point contacts I! and 60 ed across the positive terminal 2 and the negal2 and winding 8 substantially to the terminal tive terminal 3 of the source, but if the source voltage of the generator. As cars It rotates have a sufiiciently low internal resistance this ca- 'further in the same direction the circuit at pacitor will not be required for satisfactory operbreaker point contacts Hi and I2 opens and im ation of our invention. The remaining termimediately thereafter the circuit at breaker point 56 rials of capacitors 4 and I are interconnected contacts 9 and H closes. Capacitor 4 then discharges through primary winding accompanied by a substantially simultaneous charge of capacitor 'I through this same winding. Storage capacitor 2', when employed, is charged by the charging source and supplies the curent, or at least part thereof, to charge capacitors 4 and 1.

As cam l3 continues to rotate, the above cycle is repeated.

As in prior ignition systems employing capacitor discharge for the production of the. high voltage for the spark plugs, when a previously charged capacitor is discharged through the primary winding of a transformer, a sudden and rapid current surge occurs in such winding immediately after the discharge circuit is closed. This current surge causes a rapid change of flux in the primary winding of the transformer and, through the iron core, this rapidly changing flux links the secondary winding, inducing a suiiicient voltage therein to jump the gap at the spark plugs. But after the initial surge the current flow rapidly decreases as the capacitor is discharged and, when the discharge circuit is opened, the current flow has reached a very low value or has ceased entirely, and little or no arcing or sparking occurs at the breaker point contacts.

Similarly, when a partially or; completely discharged capacitor is charged through the primary winding of a transformer, a charging current surge occurs immediately after the charging circuit is closed, producing a rapidly changing flux which links the secondary winding and induces a high voltage therein. As the capacitor becomes charged its terminal voltage increases, the charging current rapidly decreases and ceases entirely when the terminal voltage of the capacitor reaches that of the generator. When the charging circuit is opened, the charging current has either reached a very low value or has ceased flowing entirely, resulting in no appreciable arcing or sparking at the breaker point contacts when the circuit is opened.

In our invention, the discharge current surge of capacitor 4 and the charging current surge of capacitor 1 occur practically simultaneously through primary winding 5 with the result that their effects are cumulative in producing an increased induced voltage in the secondary winding. Similarly, the charging current surge of capacitor 4 and the discharge current surge of capacitor 1 occur practically simultaneously through primary winding 8, with a similar effect. In addition, the flow of current in each primary coil, i. e., the charging current of one capacitor and the discharge current of the other, is always in the same direction.

When the storage capacitor 2 is employed, at no time is the current flow from the generator or other charging source completely interrupted. For a very brief interval occurring twice each cycle, when both sets of breaker point contacts are open, the only current path from the charging source is through capacitor 2'. But for the very great portion of each cycle, the charging source is charging either capacitor 4 or capacitor 1 in addition to supplying current to capacitor 2. The above results in an uninterrupted and more nearly steady flow of current from the generator.

When the internal resistance of the charging source is such that storage capacitor 2 need not be employed, the current flow from the charging source is interrupted for a very brief instant twice each cycle, but such periods of interruption are small compared with the length of the cycle. Thus, with capacitor 2' omitted from the circuit, the charging source, while not supplying current for the entire cycle, does supply current for the very great portion thereof, as compared with prior ignition systems employing capacitor discharge in which the charging source supplies current for only approximately half the cycle.

Comparing our invention with a system employing a single large capacitor the alternate charge and discharge of which each produces a secondary high voltage sufficient to jump a spark plug gap, it is apparent that our invention, while using capacitors each of which has less capacity than the capacitor employed in the system above referred to, is able to produce a secondary high voltage substantially the sameas that produced by the single capacitor system; A resulting consequence is that the peak charging current capacity required from the charging source is less with our invention and that a charging source of lower cost, smaller dimension and less weight can be successfully employed, frequently a'not inconsiderable factor especially in aircraft.

As previously mentioned, capacitors 4 and I are charged or discharged immediately after the breaker point contacts are closed, and, at the time the circuit at the breaker point contacts is broken, the current flow through. them has reached either zero or a very low value. Thus, little or no arcing occurs at the breaker point contacts when they are opened, resulting in greatly extended useful life of the breaker point contacts as compared with systems in which these breaker point contacts break an appreciable current.

Since, with capacitors 4 and I of substantially the same capacity, substantially equal voltages are induced in the secondary winding each time the breaker point contacts close, there is no necessity for introducing a current limiting resistor in any portion of the primary circuit in order to equalize the induced secondary voltages. Further, since, in our invention, the generator circuit includes one or more capacitors for any position of the breaker point contacts, a conductive circuit is never completed across the generator and a current limiting resistor is not necessary for the protection of the generator.

One desirable result from the use of low resistance transformer primary circuits, 1. e., with no current limiting resistor in the circuit, is a small time constant. Such is especially desirable with high speed engines requiring a large number of sparks per minute. a With a small time constant the rate of charge and discharge of the capacitors is suiiiciently rapid to produce a spark of substantially undiminished intensity even at high engine speeds. Our invention has successfully produced up to 20,000 sparks per minute with undiminished voltage.

Qther modifications and changes in the proportions and arrangement of the parts may be made by those skilled in the art without departing from the nature and scope of this invention, within the scope of what is hereinafter claimed.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

We claim:

1. In combination, a source of electrical energy of substantially constant potential, 'a first capacmand a second capacitor electrically connected in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondary winding, a common circuit for charging said first capacitor and for dis-' charging said second capacitor including said first primary winding and a cam actuated contact means, a common circuit for dischargingsaid first capacitor and for charging said second capacitor including said second primary winding and another cam actuated contact means, whereby cy-' clically said first capacitor is charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor is discharged and said second capacitor is substantially simultaneously discharged through said second primary winding, both said capacitorsbeing charged from said source.

2. In combination, a source of electrical energy of substantially constant potential, a first capacitor and a second capacitor electrically connected I in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondary winding, a common circuit for charging said first capacitor and for discharging said second capacitor including said first primary winding and a cam actuated contact means, a common circuit for discharging said first capacitor and for charging said second capacitor including said second primary winding and another cam actuated contact means, whereby cyclically said first capacitor is charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor is discharged and said second capacitor is substantially simultaneously discharged through said second primary winding, both said capacitors being charged from said source, the fiow of current in both said primary windings being unidirectional, both said primary windings inducing substantially equal voltages in said secondary winding.

3. In combination, a source of electrical energy of substantially constant potential, two capacitors electrically connected in series across said source, a step-up transformer having two primary windings and a secondary winding, a cam actuated contact means cyclically operable to charge one said capacitor and to simultaneously discharge the other said capacitor through one of said primary windings, and alternately to discharge the previously charged. capacitor and to almultaneously charge the previously discharged capacitor through the other said primary winding, said primary windings being alternately energized, both said capacitors being charged from said source.

4. In combination, a source of electrical energy 01 substantially constant potential, a first capaci- I tor and a second capacitor electrically connected in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondary winding, a common circuit for charging said first capacitor and for discharging said second capacitor including said first primary winding and a cam actuated contact means, a common circuit for discharging said first capacitor and for charging said second capacitor including said second primary winding and another cam actuated contact means, whereby cyclically said first capacitor is charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor is discharged and said-second capacitor is substantially simultaneously discharged through said second primary winding, and a storage capacitor connected across said source.

5. In combination, a source of electrical energy of substantially constant potential, a first capacitorand a second capacitor electrically connected in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondary winding, a common circuit for charging said first capacitor and for discharging said second capacitor -including said first primary winding and a cam actuated contact means, a common circuit for discharging said first capacitor and for charging said second capacitor including said second primary winding and another cam actuated contact means, whereby cyclically said first capacitor is charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor, is discharged and said second capacitor is substantially simultaneously discharged through said second primary winding, and a storage capacity connected across said source, the fiow o! charging current from said source being substantially uninterrupted.

6. In combination, a source of electrical energy of substantially constant potential, a first capacitor and a second capacitor electrically con-' nected in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondarywinding. a common circuit for charging said first capacitorand for discharging said second capacitor including said first primary winding and a cam actuated contact means, a common circuit for discharging said first capacitor and for charging said .second capacitor including said second primary winding and another cam actuated contact means, whereby cyclically said first capacitoris charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor is discharged and said second capaci- -tor is substantially simultaneously discharged through said second primary winding, and a storage capacitor connected across said source, the flow of current in both said primary windings being unidirectional, both said primary windings inducing substantially equal voltages in said secondary-winding,

I. In combination, a source of electrical energy of substantially constant potential, a first capacitor and a second capacitor electrically connected in series across said source, a step-up transformer having a first primary winding, a second primary winding and a secondary winding, a common. circuit for charging said first capacitor and for discharging said second capacitor including said first primary winding and a cam actuated contact means, a common circuit for discharging said first capacitor and for clurging said second capacitor including said second primary winding and another cam actuated contact means, whereby cyclically said first capacitor is charged and said second capacitor is substantially simultaneously discharged through said first primary winding, and alternately said first capacitor is discharged and said second capacitor is substantially simultaneously discharged through said second primary winding, and a storage capacitor connected across said source, the fiow of current in both said primary windings beingv unidirectional, both said primary windings inducing substan- I tially equal voltages in said secondary winding.

the now 0! charging current from said source being substantialb' uninterrupted.

8. In combination,- a source of electrical energy otsubstantialiy constant potential. two capacitorselectrically connected in series across said source, a step-up transformer having two primaryw'indings and a secondary winding, a cam actuated contact means cyclically operable to charge one said capacitor and to simultaneously discharge the other said capacitor through one of said primary windings, and alternately to discharge the previously charged capacitor and to simultaneously charge the previously discharged capacitor through the other said primary winding, said primary windings being alternately energized, and a storage capacitor connected across said source. a v

ii. In combination. a source of electrical energy or substantially constant potential, two capacitors electrically connected in series across said source, a step-up transformer having-two primary windings and a secondary winding, acam actuated contact means cyclically operable to charge one said capacitor and to simultaneously discharge the other said capacitor through one or said primary windings, and alternately to discharge the previously-charged capacitor and to simultaneously charge the previously "discharged capacitor through the other said primary winding, said primary windings being alternately energized, and a storage capacitor connected across said source, the flow oi charging current (mm 13 said source being substantially uninterrupted.

MELVILLE I". PETERS. GEORGE 1". BLACKBURN.

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