US3554178A - Dual spark capacitor discharge ignition system - Google Patents

Abstract

A capacitor discharge ignition system which produces two sparks per cylinder per compression stroke in response to each halfcycle of alternating current ignition signals. The ignition signals are applied across the base-emitter electrodes of a first normally conducting transistor which is rendered nonconductive during a selected one-half-cycle of each ignition signal cycle. As the first transistor goes nonconductive, a second transistor is triggered conductive to maintain the first transistor in the nonconducting state and a first capacitor begins to charge from a direct current potential source through a series resistor. The charging current of this capacitor produces base-emitter and, consequently collector-emitter current flow through a third transistor while the capacitor is charging. The collector-emitter current flow of this transistor produces a potential drop across an emitter resistor which is applied across the input terminals of an inverter circuit which produces the charging potential for the ignition capacitor and renders an ignition capacitor switch conductive to discharge the ignition capacitor through the primary winding of the ignition coil. With the other half-cycle of each alternating current ignition signal, the first transistor is rendered reconductive to extinguish the second transistor. As the second transistor goes nonconductive, another capacitor begins to charge through a series resistor. The charging current of this capacitor produces base-emitter and, consequently, collector-emitter current flow through a fourth transistor while the capacitor is charging. This collector-emitter current flow through the same emitter resistor, common to both the third and fourth transistors, produces a potential drop thereacross which is applied to the inverter circuit and the sequence of events is repeated as previously described.

Description

United States Patent [72] Inventors James A. Boyer;

Donald 0. Ruff, Anderson, Ind. [21] AppLNo. 838,993 [22] Filed July3, 1969 [45] Patented Jan. 12,1971 [73] Assignee General Motors Corporation Detroit, Mich. a corporation of Delaware [54] DUAL SPARK CAPACITOR DISCHARGE IGNITION SYSTEM 4 Claims, 4 Drawing Figs.

[52] U.S.C1 123/148, 315/209 [51] lnt.Cl F02p3/06 [50] FieldofSearch 123/148E, 32E-1: 315/209, 218; 307/885 [56] References Cited UNITED STATES PATENTS 3,209,739 10/1965 Jukes 123/148 3,219,877 11/1965 Konopa. 315/209 3,259,118 7/1966 Peters... 123/148 3,322,106 5/1967 Earp 123/148 3,383,556 5/1968 Tarter 315/209 Primary Examiner-Laurence M. Goodridge Attorneys-Eugene W. Christen, Creighton R. Meland and Richard G. Stahr ABSTRACT: A capacitor discharge ignition system which produces two sparks per cylinder per compression stroke in response to each half-cycle of alternating current ignition signals. The ignition signals are applied across the baseemitter electrodes of a first normally conducting transistor which is rendered nonconductive during a selected one-halfcycle of each ignition signal cycle. As the first transistor goes nonconductive, a second transistor is triggered conductive to maintain the first transistor in the nonconducting state and a first capacitor begins to charge from a direct current potential source through a series resistor. The charging current of this capacitor produces base-emitter and, consequently, collectoremitter current flow through a third transistor while the capacitor is charging. The collector-emitter current flow of this transistor produces a potential drop across an emitter resistor which is applied across the input terminals of an inverter circuit which produces the charging potential for the ignition capacitor and renders an ignition'capacitor switch conductive to discharge the ignition capacitor through the primary winding of the ignition coil. With the other half-cycle of each alternating current ignition signal, the first transistor is rendered reconductive to extinguish the second transistor. As the second transistor goes nonconductive, another capacitor begins to charge through a series resistor. The charging cur rent of this capacitor produces base-emitter and, consequently, collector-emitter current flow through a fourth transistor while the capacitor is charging. This collectoremitter current flow through the same emitter resistor, common to both the third and fourth transistors, produces a potential drop thereacross which is applied to the inverter circuit and the sequence of events is repeated as previously described.

PATENTEUJAN12|91| 3,554; 78

sum 1 or z fazzzes Hf KMAZM/ ATTORNEY DUAL SPARK CAPACITORDISCHARGE IGNITION SYSTEM f This invention is directed to a dual-spark capacitor discharge ignition system and, more specifically, to the circuit included therein which produces two like polarity output signal pulses in response to each alternating current input signal cycle.

It has been found that the fuel ignition spark produced by prior art capacitor discharge'ignition systems is of an insufiicient duration to provide adequateengine performance at intermediate and low engine speeds. Consequently, a capacitor discharge ignition system which provides two ignition sparks per cylinder per compression stroketo improve engine performance at these engine speeds is desirable.

It is, therefore, an object of this 'inventionto' provide an improved capacitor discharge ignition system.

It is another object of this invention-t provide an improved circuit which will produce two like polarity output pulses in response to each alternating current input signal cycle.

It is another object of this invention to provide an improved capacitor discharge ignition system which produces two ignition sparks per cylinder per compression stroke.

' It is a further object of this inventionto provide a circuit which is responsive to each alternating current input ignition signal cycle to provide two like polarity output signals which are employed by associated converter andoutput stages of a capacitor discharge ignition system to supply two'ignition sparks per cylinder per compression stroke.

In accordance with this invention, a dual-spark capacitor discharge ignition system is provided wherein a circuit'responsive to each alternating current input ignition signal cycle to produce two like polarity output signals is employed in com bination with a converter stage and an output stage to produce two ignition sparks per cylinder per compression stroke.

For a better understanding of the present invention, together with additional objects, advantages and features thereof, reference is made to the following description and accompanying drawings wherein:

FIG. 1 schematically sets forth'the dual-spark capacitor discharge ignition system of this invention.

FIG. 2 is an elevation view, partially in'cross section, of a magnetic-type distributor suitable for use with the capacitor discharge ignition system of this invention,

FIG. 3 is a section view of FIG. 2 taken along line 3-3 and looking in the direction of the arrows, and

FIG. 4 illustrates one cycle of the alternating current ignition' signal potential waveform produced by the magnetic distributor of FIGS. 2 and 3.

As the point of reference or. ground potential is the same point electrically throughout the system, it has been represented by the accepted schematic symbol and referenced by the numeral 5 in FIG; 1. n

Corresponding elements of FIGS. 1, 2 and 3 have been given like characters of reference throughout these figures.

Referring to the figures, the capacitor discharge ignition system of this invention for use with intemal combustion engines is shown to include an output stage set forth within dashed rectangle 10, having an ignition capacitor 14 and a charging circuit therefor, to be explained in detail later, the primary winding 16 of an ignition coil 15 which also has a secondary winding 17, and electrically operable ignition capacitor switch 18 for connecting the ignition capacitor 14 across the ignition coil primary winding 16, a converter circuit stage set forth within dashed rectangle 11, for producing the potential which provides the charge upon the ignition capacitor 14 in response to each input signal cycle having an input circuit and an output circuit across which the ignition capacitor charging circuit and the ignition capacitor switch are connected, a source of alternating current ignition signals produced in timed relationship with the internal combustion engine with which the ignition system is being used, FIGS. 2 and 3, and a circuit for producing two like polarity output signal pulses in response to each alternating current input signal cycle, set forth within dashed rectangle 12.

One example of a source of alternating current ignition signals which may be used with the ignition system circuit of this invention is set forth in FIGS. 2 and 3 as a magnetic-type distributor for producing alternating current ignition signals in timed relationship with the engine. Referring to FIG. 2, the magnetic type distributor includes a rotor member 20 of magnetic material rotated in timed relationship with the internal combustion engine with which the ignition system is being used having a pole tip corresponding to each engine cylinder, typically referenced at 21 in FIG. 3, a stationary pole piece 22 of magnetic material having a rotor accommodating bore 23 with a plurality of substantially rectangular notches 24, one for each engine cylinder, equally spaced about the circumference of the bore 23, a annular permanent magnet 25 and a pickup coil 26 would wound upon a spool 27 of an insulating material. For an eight cylinder engine, rotor member 20 has eight pole tips 21 and stationary pole piece 22 has eight notches 24, as best observed in FIG. 3. With engines of more or less cylinders, correspondingly more or less pole tips 21 and notches 24 would be required. Rotor member 20 is rotated in timed relationship with the engine with shaft 28, joumaled in bearings 29 and 30 in tubular section 31, which is rotated by a gear 32 when the gear 32 is driven by a suitable meshing gear, not shown, in the internal combustion, engine in a manner well known in the art.

Annular permanent magnet 25 is clamped between pole piece 22 and a timing plate 33 by a plurality of fasteners 34 which are threaded through suitable openings in timing plate 33. A magnetic circuit may be traced from the top end, as looking at FIG..2, of permanent magnet 25, through stationary pole piece 22, across an airgap between stationary. pole piece 22 and rotor 20, through rotor 20, a bushing meinber 35 and timing plate 33 to the opposite end of permanent magnet 25. With rotor member 20 being rotated by the engine, the reluctance of this magnetic circuit increases abruptly as a pole tip 21; of rotor 20 passes one edge of a notch 24 in stationary pole piece 22 in a direction toward the notch with a corresponding abrupt decrease of flux density therethrough. As the pole tip 21 passes the opposite edge of a notch 24, the reluctance of the magnetic circuit decreases abruptly with a corresponding increase in flux density through the magnetic circuit. These abrupt changes in flux density, as rotor 20 rotates, induce a series of alternating current potential signals in pickup coil 26, one cycle of which is illustrated in FIG. 4. For purposes of this specification and without intention or inference of a limitation thereto, the leading edge of this waveform will be assumed to be in a'positive direction as is set forth in FIG. 4. The alternating current in ignition signals thus induced in pickup coil 26 may be conducted to external circuitry through external leas leads or wires 36 and 37.

- A direct current potential source, which may be a conventional storage battery 8, is provided for supplying an operating potential. If desired, the potential of battery 8 may be regulated by a type NPN regulating transistor 50 and the associated circuitry to provide a substantially constant operating potential for the circuit which produces two output pulses in response to each alternating current input signal cycle. Collector electrode 52 and emitter electrode 53 of type NPN transistor 50 are connected across the positive and negative polarity terminals, respectively, of battery 8 through positive polarity line 44 and the series combination of resistor 45, diodes 46 and 47 and point of reference or ground potential 5, respectively, upon the closure of moveable contact 49 of switch 48 which may be one pole of a conventional automotive ignition switch. Upon the closure of switch 48, therefore,

the collector-emitter electrodes of type NPN regulating transistor 50 are properly poled for collector-emitter current flow through transistor 50. Base electrode 51 of regulating transistor 50 is connected to junction 54 between resistor 55 and zener diode 56, connected in series across respective positive and negative polarity terminals of potential source 8 through positive polarity line 44 anddiode 47 and point of reference or ground potential 5 upon the closure of movable contact 49 of switch 48.

The circuit for producing two like polarity output signal pulses in response to each alternating current input signal cycle includes an input circuit across which the input signals may be applied, which may be terminals 38 and 39 of any other of several electrical devices suitable for connection to external circuitry; first and second transistors, shown in FIG. I as type NPN transistors 60 and 70, and each having two current-carrying electrodes connected in parallel across the direct current potential source and a control electrode with the control electrode of the second transistor 70 interconnected with one of the current-carrying electrodes of the first transistor 60 in such a manner that the second transistor 70 is conductive when the first transistor 60 is nonconductive and nonconductive when the first transistor 60 is conductive; circuitry for applying the alternating current input signals across the control electrode and a selected one of the current-carrying electrodes of the first transistor 60 for rendering transistor 60 nonconductive during a selected one-half cycle of each one of the alternating current input signal cycles and conductive during the other one-half cycle of each one of the alternating current input signal cycles; third and fourth transistors, shown in FIG. 1 to be type NPN transistors 80 and 90, and each having two current-carrying electrodes connected in parallel across the direct current potential source and a control electrode; and output circuit across which the output signal pulses appear, which may be terminal 75 and point of reference or ground potential 5; a first circuit interconnected with the control electrode and a selected one of the current-carrying electrodes of a selected one of transistors 80 and 90 and responsive to the first transistor 60 becoming nonconductive for rendering the selected one of transistors 80 and 90 conductive for a predetermined period of time for producing a first output signal across the output circuitry and a second circuit interconnected with the control electrode and a selected one of the current carrying electrodes of the other one of transistors 80 and 90 and responsive to transistor 70 becoming nonconductive for rendering the other one of transistors 80 and 90 conductive for a predetermined period of time for producing the second output signal across the output circuit.

The current-carrying electrodes, collector electrode 62 and emitter electrode 63, of type NPN transistor 60 and the current carrying electrodes, collector electrode 72 and emitter electrode 73, of type NPN transistor 70 are connected across the positive and negative polarity terminals, respectively, of direct current potential source 8 through respective series resistors 84 and 85, regulated positive polarity potential line 57, the emitter-collector electrodes of regulating transistor 50 and positive polarity line 44 and point of reference or ground potential 5, respectively, upon the closure of movable contact 49 of switch 48. Upon the closure of switch 49, therefore, both these type NPN transistors are properly poled for collectoremitter conduction. If it should be elected not to regulate the potential of direct current potential source 8, resistors 84 and 85 would be connected to positive polarity line 44.

So that second transistor 70 is maintained nonconductive while first transistor 60 is conducting and is rendered conductive when transistor 60 goes nonconductive, the control electrode, base electrode 71 of transistor 70 is connected to the collector electrode 62 of transistor 60 through current limiting resistor 86.

To apply the alternating current input signals across the control electrode and a selected one of the current-carrying electrodes of the first transistor 60, pickup coil 26 may be connected across input terminals 38 and 39 through leads 36 and 37, as schematically shown in FIG. 1.

These signals are applied across base electrode 61 and emitter electrode 63 of transistor 60 through diode 87 and bias resistor 88 and lead 89, series diodes 46 and 47 and point of reference or ground potential 5.

The current-carrying electrodes, collector electrode 82 and emitter electrode 83 of type NPN transistor 80 and the current-carrying electrodes, collector electrode 92 and emitter electrode 93, of type NPN transistor 90 are connected in parallel with each other and across the positive and negative polarity terminals, respectively, of direct current potential source 8 through lead 94, regulated positive polarity potential line 57, the emitter-collector electrodes of regulating transistor 50 and positive polarity line 44 and the series combination of emitter resistors 95 and 96 and point of reference or ground potential 5, respectively, upon the closure of movable contact 49 of switch 48. Upon the closure of switch 48, both of these type NPN transistors are properly poled for collector-emitter conduction.

The first and second circuits interconnected with the control electrode and a selected one of the current-carrying electrodes of a selected one of the third and fourth transistors and and responsive to the first transistor 60 becoming nonconductive for rendering the selected one of the third and fourth transistors conductive for a predetermined period of time for producing a first output signal across the output circuitry may be respective R-C circuits connected across the current-carrying electrodes of respective transistors 60 and 70. The series combination of capacitor and resistor 106 is connected across the current-carrying electrodes of transistor 60 through lead 107 and point of reference or ground potential 5 and the series combination of capacitor 115 and resistor 116 is connected across the current-carrying electrodes of transistor 70 through lead 117 and point of reference or ground potential 5.

The control electrode, base electrode 91, of transistor 90 is connected to junction 108 between capacitor 105 and resistor 106 and the control electrode, base electrode 81, of transistor 80 is connected to junction 118 between capacitor 115 and resistor 116. With these connections, transistors 80 and 90 will be rendered conductive while respective capacitors I15 and 105 are charring when the corresponding respective transistors 60 and 70 are nonconductive.

With either one of transistors 80 or 90 conducting, an output signal appears across one common emitter resistor 96 which may be taken across output terminal 75 and point of reference or ground potential 5 and applied to external circuitry.

The current responsive converter circuit of this invention includes a converter transformer 124 having a primary winding 125 and a secondary output winding 126, across which external utilization circuitry may be connected, a control resistor 128 and normally-not-conducting-type NPN transistor 120, having collector electrode 122 and emitter electrode 123 connected in series with primary winding 125 of converter transformer 124 and the control resistor 128 across direct current potential source 8, a trigger circuit for producing a trigger signal in response to each input signal pulse, shown in FIG. 1 as a normally-not-conducting-type NPN transistor and the associated circuitry, a control circuit responsive to the potential drop across control resistors 128 for disenabling the trigger circuit when the potential drop thereacross has reached a predetermined magnitude, shown in FIG. 1 as normally-conducting-type NPN transistor 100 and the associated circuitry, and a circuit for applying the potential drop which appears across control resistor 128 to the control circuit. shown in the FIG. as lead 129 and resistor 127.

Upon the closure of movable contact 49 of switch 48, a circuit is established for base-emitter current flow through transistor 60 which may be traced from regulated positive polarity potential line 57, through resistor 85, resistor 119, diode 87, the base-emitter junction of transistor 60 and point of reference or ground potential 5. Consequently, transistor 60 is normally conducting. With transistor 60 conducting, the base electrode 71 and emitter electrode 73 of transistor 70 are of substantially the same potential, consequently, transistor 70 is nonconductive, capacitor 105, substantially short circuited by the collector-emitter electrodes of transistor 60, remains substantially uncharged to interrupt the base-emitter circuit for transistor 90 which, consequently, is normally not conducting. With transistor 70 not conducting, capacitor charges through a circuit which may be traced from regulated positive polarity potential line 57 through resistor 85, line I I7,

'transis'tor 60 abruptly goes nomionductive;

I potential 5 andthep te capacitor 115-, the bas'eemitte r electrodes of transistor 80 and series resistors 95 and 96- to point of reference or ground potential 5. This'base-emitter current'flow'through type NPN transistor 80 produces conducting through the collectoremitter electrodes of this device during the period'of charge of capacitor 115; A jcircuitlfor base-emitter current flow through type NPN transistor-lollmay be traced from positive polarity line 44 through the'primary winding 125 of transformer 124, through resistor l2 7,.the base-emitter'electrodes of transistor .100 and point of reference or groundi potential 5, Con- As transistor 60 goes conductive, the conduction through the collector-emitter electrodes thereof establishes a discharge path for capacitor 105 and reduces the potential across the base-emitter electrodes of transistor 70 to substantially zero to extinguish transistor 70. As transistor 70 goes nonconductive, capacitor 115 begins to charge through a cirsequently, transistor 100 -is normally conducting. With a transistor 100 conducting, the basefelectrode 111" of type NPN transistor llis at substantially the same potential as emitter electrode113 thereof, consequently, typefNPN transistor 110 'is-nonconductive' while transistor 1'00 is-jconducting. With 4 transistor 110' nonconductive, the base-emitter circuit of type NPN transistor 120 is interrupted, consequently; transistor 120 is also nonconduc'tive while transistorlllfl is-conducting. Over the initial half-'ci'ycl'of the alternating cu'rrent'input ignition signal, for purposes of 'this specification, that input tercuit which may be traced from regulated positive polarity line 57 through resistor 85, lead 117, capacitor 115, resistor 1 16 and point of reference or ground potential 5. v The charging'current of capacitor 115 produces a potential drop across series resistor 1 16 which is of a positive polarity at junction 1l8 with respect to point of reference or ground potential 5. As base electrode 81 of transistor 80 is connected to junction 118 and emitter electrode 83 thereof is connected to point of reference or-ground potential through series emitter resistors 95 and 96, the potential drop produced by capacitor 115 charging current through resistor 116 is applied across the base-emitter electrodes of transistor 80. in the corminal 38 is of apositive polarity with respe'cft to input terminal 39. As this is not the correct polarity relationship to produce base-emitter. current flow through) a type NPN transistor,

As transistor 60g'o'es nonconductive,-capacitor 105 begins 1 to charge through aicircuit which may; be traced from regulated positive polarity'lines'l throughresistor-84, lead 107, capacitor 105, resistor-106andpoint'of reference or ground transistor 70' goes p e with respect to thefeniitter elec- -trode 73' thereof, the correct polarity relationship; toproduce base-emitter current flowthrough a typelNPN transistor. Con-- I ,seq'uently, transistor onductsythrough th'e :collectoremitter;elect'rodes thereof to provide' a dischargepath for 'al'of base electrode 71 of type NPN.

capacitor 115. {Conductingtransistori'70fialso' maintains transistor 60fnonconductive by reducing the potential across the base-emitter electrodes thereoftosubstantiallyfzero. The charging'curr'ent of capacitor 105 producesla potential drop across series resistor106 which is of a 'positivefpolarity at junction 108 with respect to; point of reference or ground potential 5. As base'electrode 91 of transis'tor 90 is connected to junction108 and emitter electrode 9.3 meteors-summed to I point. of refer ence or ground potential. 5 through series emitter resistors 95' and 96, the potential drop produced by capacitorl05 charging current through resistor 106 is applied, acrossthe base-emitter'electrodesof'transistor 90 in the correct polarity relationship toprodu'ce base-emitter current flow through this type-NPN transistor. Consequently, when the potential drop across resistor 116 reaches a magnitude substantially equal to the breakdown potential of the baseemitter junction of the transistor selected. asa transistor 80, baseemitter current and, consequently, collector-emitter current flows through this device. When capacitor 115 has become charged after apredetermined period of time as determined by the time constant of the'R-C circuit including capacitor 115 connected in series with the parallel combination of'resistor 116 and series resistors 95 and 96, the circuit through which base-emitter current flows through'transistor 80 is in terrupted, consequently, this device goes nonconductive.

With transistor 80 conducting through thecollector-emitter electrodes for the predetermined period of time as determined by the time constant of series'connected.capacitor 115 and resistor 116, current flows through the series emitter resistors 95 and 96. The potential drop across emitter-resistor 96, as a result of this current flow, may be taken as an output signal pulse across output terminal 75 and point of reference or ground potential 5 and is of a positive polarity at output ter- 'minal 75 with respect to point ofreference or ground potential 5;- This is the second output pulse and is of the same polarity as thefirstoutput pulse.

rect-polarity relationshipto produce base-emitter current'flow through'this type NPN transistor. Consequently; when the potentialfldrop aerossresistOr .106 reaches a'magnitude' substantially equalto the breakdown potential of the base-emitter junction of the transistorselected as transistor 90, baseemitter current, and consequently, collector-emitter current flow throughthis device. When capacitor 105 has become charged after a prede'termined periodof time as determined by the time constant of the R-C circuit including capacitor 105 connected in series with the parallel combination of re sistor 106 and series resistors 95 and 96, the'circuit' through which base-emitter current flows through transistor 90'is interrupted, consequently, this device goes nonconductive.

With transistor 90-conducting through the collector-emitter electrodes for'the predetermined periodof time as determined by the time constant of series connected capacitor 105 and resistor 106, current flows through the series emitter resistors 95 I and 96. The potential'drop across emitter resistor 96, as a result of this current flow, may be taken as an output signal pulse across output terminal 75 midpoint of reference or ground potential 5 and is of a positive'polarity at output terminal 75 withrespect topoint of reference'or ground potential Overthe second half-cycle'of the alternating current input ignition signal, input terminal 39 is of a positive polarity with respect to inputterminal 38.- .As this is the correct polarity relationship to producebase-emitter current flow through a type NPN transistor, transistor abruptly goes conductive.

The signal pulses produced by the circuitry just described appear across output terminal and point of reference or ground potential 5, are of a positive polarity at output terminal 75 with respect to point of reference orground potential 5 and are applied across "the base-emitter electrodes of trigger I through the collector-emitter electrodes of trigger transistor 1 l0 and series resistor 135. The resulting current flow through resistor 135 produces a trigger signal thereacross which is of a positive polarity at junction 136 with respect to point of references or ground potential 5. This trigger signal is applied across the base-emitter electrodes of switching transistor 120 and is of the correct polarity relationship to produce baseemitter current flow, and consequently, collector-emitter current flow through a type NPN transistor; Consequently, type NPN switching transistor 120 is triggered conductive through the collector-emitter electrodes by the trigger signals produced by the trigger circuit.

Conducting switching transistor 120 connects the positive polarity end, junction 138, of base-bias circuit resistor 127 of control transistor to point of reference or ground potential 5 through control resistor 128,'a condition which results in a potential across junction l38and point of reference or ground potential 5 which'is of a positive polarity upon junction 138 with respect to point of reference or ground potential and of a magnitude equal to the potential drop across control resistor 128 and the collector-emitter electrodes of switching transistor 120. Therefore, control resistor 128 is selected to have a resistance value which, upon the initial conduction of switching transistor 120, will result in a total potential drop, thereacross and the collector-emitter electrodes of switching transistor 120 of an insufficient magnitude to maintain base drive current through the base-emitter electrodes of control transistor 100, thereby extinguishing this device.

With control transistor 100 extinguished upon the initial conduction of switching transistor 120, a base drive circuit for maintaining base-emitter current flow through trigger transistor 110 is established through the series combination of resistor 139 and diode 140, the base-emitter electrodes of trigger transistor 110 and resistor 135 to maintain trigger transistor 110 and, consequently, switching transistor 120 conductive. Conducting switching transistor 120 establishes an energizing circuit for the series combination of primary winding 125 of converter transformer 124 and control resistor 128 across direct current potential source 8.

With the energizing circuit completed for primary winding 125 of converter transformer 124, energizing current which increases in magnitude, flows through primary winding 125 of converter transformer 124 and produces an increasing primary winding 125 magnetic field which induces a potential in secondary winding 126 thereof of a positive polarity at terminal 145 with respect to terminal 146, and a potential in switch winding 147 of a positive polarity at terminal 148 with respect to terminal 149. Blocking diodes 150 and 151 prevent the flow of current through secondary winding 126, consequently, the potential induced in secondary winding 126 is of no effect. The purpose of the potential induced in switch winding 147 will be explained in detail later in this specification.

As energizing current flow through primary winding 125 of converter transformer 124 and control resistor 128 continues to increase in magnitude, the potential upon junction 138 increases in magnitude. This positive polarity potential signal is applied across the base-emitter electrodes of control transistor 100 through resistor 127 and point of reference or ground potential 5 in the correct polarity relationship to produce base-emitter current flow through type NPN control transistor 100. When the potential drop across control resistor 128 reaches the predetermined magnitude. This signal produces base-emitter and, consequently, collector-emitter conduction through control transistor 100 to trigger this device conductive through the collector-emitter electrodes.

Conducting control transistor 100 diverts base current from trigger transistor 110 to extinguish this device. With trigger transistor 110 extinguished, the trigger signal appearing across resistor 135 is removed from across the base-emitter electrodes of switching transistor 120, consequently, switching transistor 120 extinguishes to interrupt the energizing circuit for primary winding 125 of converter transformer 124.

The resulting collapsing primary winding 125 magnetic field induces the ignition capacitor 14 charging potential in secondary winding 126 thereof, which is ofa positive polarity at ter minal 146 with respect to terminal 145, and a potential in switch winding 147, which is ofa positive polarity at terminal 149 with respect to terminal 148. The ignition capacitor 14 charging potential induced in secondary winding 126 charges ignition capacitor 14 through a circuit which may be traced from terminal 146, through diodes 150 and 151, ignition capacitor 14, primary winding 16 of ignition coil 15, point of reference or ground potential 5 and the parallel combination of resistor 152 and the series connected resistor 153 and the base-emitter electrodes of transistor 130 to the other terminal 145 of secondary winding 126. Ignition capacitor 14 is now charged with an ignition potential with the plate thereof connected to junction 154 being of a positive polarity with respect to the other plate. Diode 155 prevents the flow of current through switch winding 147, consequently, the potential induced in switch winding 147 is of no effect.

The charge upon ignition capacitor 14 is applied across the anode-cathode electrodes of silicon-controlled rectifier ignition capacitor switch 18 through lead 156 and through the primary winding 16 of ignition coil 15 and point of reference or ground potential 5. As the polarity of the charge upon ignition capacitor 14 is positive upon the plate connected to junction 154, the polarity of the potential applied across the anodecathode electrodes of silicon-controlled rectifier ignition capacitor switch 18 is positive upon the anode electrode and negative upon the cathode electrode.

The silicon-controlled rectifier is a semiconductor device having a control electrode, generally termed the gate electrode, and two current carrying electrodes, generally termed the anode and cathode electrodes, which is designed to normally block current flow in either direction. With the anode and cathode electrodes forward poled, anode positive and cathode negative, the siliconcontrolled rectifier may be triggered to conduction upon the application to the control electrode, of a control potential signal of a polarity which is positive in respect to the potential present upon the cathode electrode and of sufficient magnitude to produce control electrode-cathode, or gate, current. ln the conducting state, the silicon-controlled rectifier will conduct current in one direction and retains the ability to block current flow in the opposite direction. In the conducting state, therefore, the silicon-controlled rectifier functions as a conventional diode. Upon being triggered to conduction, however, the control electrode is no longer capable of affecting the device which will remain in the conducting state until either the anode cathode circuit is interrupted or the polarity of the potential applied across the anode-cathode electrodes is reversed. Of these two alternatives, the reversal of the polarity of the potential across the anode-cathode electrodes thereof is perhaps the most satisfactory.

Upon the next input signal pulse across terminal 75 and point of reference or ground potential 5, the sequence of events just described is repeated. With the next initiation of conduction of switching transistor 120, the increasing primary winding magnetic field produced as a result ofincreasing energizing current flow therethrough induces a potential in switch winding 147 of a positive polarity at terminal 148 with respect to terminal 149. This potential produces a current flow through a circuit which may be traced from terminal 148 through diode 155, the parallel combination of resistor 160 and series connected capacitor 161 and resistor 162 and point of reference or ground potential 5 to terminal 149. The capacitor 161 charging current flows through resistor 162 and produces a potential signal thereacross which is of a positive polarity at junction 163 with respect to point of reference or ground potential 5. This signal is applied across the gatecathode electrodes of silicon-controlled rectifier ignition capacitor switch 18 in the proper polarity relationship to produce gate current through this device. As the charge on ignition capacitor 14 is applied across the anode-cathode electrodes of silicon-controlled rectifier ignition capacitor switch 18 in the correct anode-cathode polarity relationship, this device conducts through the anode-cathode electrodes thereof to connect ignition capacitor 14 across the ignition coil primary winding 16. Consequently, ignition capacitor 14 discharges rapidly through primary winding 16 of ignition coil 15 and the discharge current produces a magnetic field which induces a high firing potential in secondary winding 17. The firing potential is directed to the ignition coil terminal of a conventional automotive-type distributor, not shown.

With high engine speeds, the two pulses produced by the circuitry of dashed rectangle 12 may become so closely spaced that the second pulse occurs before ignition capacitor 14 has become completely charged. In this event, the second pulse will trigger silicon-controlled rectifier 18 conductive while ignition capacitor 14 is charging. That is, charging and discharging circuits for ignition capacitor 14 are established simultaneously. To prevent this undesirable situation, a pulsecanceling transistor having the usual base 131, collector 132 and emitter 133 electrodes is provided. The collector electrode l32is connected to the junction between diode 140 and the base electrode of trigger transistor 110 the emitter electrode 133 is connected to terminal 145 of secondary'winding 126 and the base electrode'il'3l is connected to pointof reference or ground potential through resistor 153. As ignition'capacitor- 14. charges,.charging current flowsthrough resistor 152 in a direction from point of reference or'ground' potential 5 toward terminal145 of secondary winding 126,

- collector-emitter electrodes of pulse-canceling transistor 130,

which are connected in shunt with trigger transistor 110, consequently, the second pulse would be in'effectiveito trigger transistor I10 and, consequently, switching transistor 120 conductive at this time. As the. terminal 149 of switch winding 147 is of a positive polarity with'respect' totermin'al I48 thereof, resistor 165 is connected between terminal 148 and the collector electrode of pulse-canceling transistor 130 to provide an additional positive polarity potential upon collector electrode 132 of pulse-cancelingtransistor 130 to provide additional insurance that'pulse-canceling =transistor 130 will conduct with each second input pulse which" is produced during the periods ignition capacitor 14 is charging.

With an open ignition coil secondary,-the series L-C circuit comprising primary winding 16 of ignitioncoillS and ignition capacitor 14 produces a ringing action which charges ignition capacitor 14 in the reverse direction. Ignition capacitor 14 then discharges in the reverse direction throughp rimary winding 16. The ring back of ignition capacitor 14 in a reverse direction extinguishes silicon-controlled rectifier l8.

Resistor 168.connected'in parallel with ignition coil primary winding 1 25 rapidly'dampens the oscillations through primary winding'lZS while the ignition systemfisfiring across a spark plugzgap; resistor 170- isa .bleeder" resistor through'which ignition capacitor 14 discharges when switch 49 is opened; and capacitor 172'isafilter. g

Throughout the specification, specific transistor-types, electrical polarities and circuit elements have' been set forth. It is;

to be specifically understood, however, that alternate transistor types and compatible electrical polarities and'altemate circuit elements possessing.:similar electrical. characteristics may be substituted withoutdeparting from the spirit of the invention. v Y v Weclaim: Y 1. in a capacitordischarge ignition system for use with internal combustion engines of the type including an output stage nition capacitor across the ignition coil, primary winding and a converter circuit stage for producingthepotential which provides'thecharge .uponthe ignition capacitor in response to each .input signal cycle 'having an input. circuit and an output circuit'across which the ignition capacitor charging circuit andthe ignition capacitor switch are connected, the'means for producing two like polarity output signal pulses in response to' each alternating current input signal cycle comprising in combination .with a direct current potential source, a magnetic. pulse generator including at least a rotormember'of magnetic material rotated in timed relationship with the internal com-1 tial source:

the circumference of the bore, a pe'rmanentmagnet and a pickup coil for producing alternatingcurrent ignition signals in timed relationship with the e g first and second transistors each having two current-carrying electrodes and a control electrode:

means for connecting said current-carrying electrodes of 7 both said transistors in parallel across said direct current potential source:

means for interconnecting said control electrode of said I second transistor "and one of s'aidcurrent-carrying electrodes of said first transistor in such a mariner that said second transistor is conductive when said first transistor is nonconductive and is nonconductive when said first transistor is conductive;

means for applying said alternating current ignition signals across said control electrode and a selected'one of said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current ignition signal cycles and conductive during the other one-half cycle of each one of said alternating current ignition signals;

first and second capacitors;

first and second resistors;

means for connecting the series combination of said first capacitor and said first resistoracrosssaid current-carrying'electrodesof a selected one of .said first and second transistors;

means for connectingthe series combination of said second rendered conductive while said first capacitor charges when said selected one of said first and second transistors across the said current-carrying electrodes of which said series combination of said fii-stcapacitor and said first resistor is connected is nonconductive;

means for connecting said control-electrode of the other one of said third and fourth transistors to the junction between said second capacitor and said second transistor wherebysaid other one of said third and fourth transistors is rendered conductive while said secondcapacitor charges when the oth'er one of said first and second transistors across the current-carrying electrodes of which said series combinationof said second capacitor and saidsecond resistor is connected is nonconductive;

. and at least one common resistor included in said means for connecting said current-carrying electrodes of said third and fourth transistors in parallel across said direct current potential source across which an output signal appears while either one of said third and fourth transistors is conducting.

1 2. A circuit for producing two like polarity outputsignal pulses in response to each alternating current'input signal cycle comprising in combination with a direct current potenfirst and second transistors each having two current-carrying electrodes connected inp'arallel across said direct current potential source and a control electrode;

meansfor interconnecting said control electrode of said second transistor and one of said current-carrying eleo trodes of said first transistor in such a mannerthat said second transistor is conductive when said first transistor is nonconductive and, is nonconductive when said first transistor is conductive; f

, meansfor applying said alternating current input signals across said control electrode and a selected one of -said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current signal cycles and conductive during the other one-half cycle of each one of said alternating current signals;

third and fourth transistors each having two current-carrying electrodes connected in parallel across said source of direct current potential and a control electrode;

fourth transistors for rendering said other one of said third and fourth transistors conductive when said second transistor becomes nonconductive for a predetermined period of time for producing a second output signal across said output circuit means.

4. A circuit for producing two like polarity output signal pulses in response to each cycle of an alternating current input signal cycle comprising in combination with a direct current potential source:

output circuit means; first and second transistors each having two current-carryfirst circuit means interconnected with said control elecmg electrodes. conneaed m Parallel across a d'rect trode and a selected one of said current-carrying elec- Current PPtenUaISOurPe control electrode nodes of a selected one of Said third and fourth means for interconnecting said control electrode of said transistors and responsive to said first transistor becoming second tran.slstor and ope of cunem'canymg 15 trodes of said first transistors in such a manner that said nonconductive for rendering said selected one of said third and fourth transistors conductive for a predate! second transistor is conductive whensaid first transistor is mined period of time for producing a first output signal noncfmdupuve is nonconductive when sald first transistor is conductive; t

acrossfsaldputpm circun meansand. means for applying said alternating current input signals second circuit means interconnected with said control elecacross Said control electrode and a selected one of said node and a Selected one f currem'canymg current-carrying electrodes of said first transistor for trodes of the other one of said third and fourth transistors rendering Said first transistor nonconductive during a and mshonswe to 9 trans'stor P n selected one-half cycle of each one of said alternating conductive for rendering said other one of sa d third and current Signal cycle and conductive during tm other one, foufth translstors cfmducuve for a predefermmed Pemfd half cycle of each one of said alternating current signals; of time for producing a second output signal across said first and Second capacitors; PP 'f means first and second resistors;

A ("mull for Producmg two like P i output sfgnal means for connecting the series combination of said first pulses in response to each cycle of an alternating current input capacitor and said fi resistor across Said currenpcan) signal cycle comprising in combination with a direct current ing electrodes f a Selected one f Said fi and Second potential source; transistors;

first and second "ansistors each having two current*cany means for connecting the series combination of said second ing electrodes connected in Parallel across said dh'eet capacitor and said second resistor across said current-carcul'rem Potential Source and a control electrode; rying electrodes of the other one of said first and second means for interconnecting said control electrode of said transistors;

second transistor and one of said current-carrying electhird and fourth transistors each having two current-carrytrodes of said first transistor in such a manner that said i l t od d a t l l t d second transistor is conductive when said first transistor is means for connecting said current-carrying electrodes of nonconductive and is nonconductive when said first said third and fourth transistors in parallel across said transistor is conductive; 40 direct current potential source.

means for applying said alternating current input signals means for connecting said control electrode of a selected across said control electrode and a selected one of said one of said third and fourth transistors to the junction current-carrying electrodes of said first transistor for between said first capacitor and said first resistor whereby rendering said first transistor nonconductive during a said selected one of said third and fourth transistors is selected one-half cycle of each one of said alternating rendered conductive while said first capacitor charges current signal cycles and conductive during the other when said selected one of said first and second transistors one-half cycle of each one of said alternating current across the said current-carrying electrodes of which said signals; series combination of said first capacitor and said first rethird and fourth transistors each having two current-carrysister is Connected is nonconductive;

ing electrodes connected in parallel across said source of means for connecting said control electrode of the other dire t rrent tential and ont l le d one of said third and fourth transistors to the junction output circuit means; between said second capacitor and said second transistor a first R-C circuit connected across said current-carrying whereby said other one of said third and fourth transistors electrodes of said first transistor and interconnected with is rendered conductive while Said second capacitor said control electrode and a selected one of said currentge when the other one of said first and second carrying electrodes of a selected one of said third and e o e curremfiarrying electrodes ofwhieh fourth transistors for rendering said selected one of said 531d senesfiomhmauon of l Second capacitor and said third and fourth transistors conductive when said first Second Teslstol' eonneetedls honeondflenvefind transistor becomes nonconductive for a predetermined at least W common "eslstor 'P 531d means period of time for producing a first output signal across connecting y g electrooes o said third said Output circuit means; and and fourth transistors in parallel across said direct current a second R-C circuit connected across said current-carrying f f source acrqss Output '5 PP electrodes of said second transistor and interconnected enher one of sad thud and fourth "an-slams with said control electrode and a selected one of said curductmg rent-carrying electrodes of the other one of said third and

Claims (4)

1. In a capacitor discharge ignition system for use with internal combustion engines of the type including an output stage having at least an ignition capacitor and a charging circuit therefor, the primary winding of an ignition coil and an electrically operable ignition capacitor switch for connecting the ignition capacitor across the ignition coil primary winding and a converter circuit stage for producing the potential which provides the charge upon the ignition capacitor in response to each input signal cycle having an input circuit and an output circuit across which the ignition capacitor charging circuit and the ignition capacitor switch are connected, the means for producing two like polarity output signal pulses in response to each alternating current input signal cycle comprising in combination with a direct current potential source, a magnetic pulse generator including at least a rotor member of magnetic material rotated in timed relationship with the internal combustion engine with which the ignition system is being used having a pole tip corresponding to each engine cylinder, a stationary pole piece of magnetic material having a rotoraccommodating bore with a plurality of substantially rectangular notches, one for each engine cylinder, equally spaced about the circumference of the bore, a permanent magnet and a pickup coil for producing alternating current ignition signals in timed relationship with the engine: first and second transistors each having two current-carrying electrodes and a control electrode: means for connecting said current-carrying electrodes of both said transistors in parallel across said direct current potential source: means for interconnecting said control electrode of said second transistor and one of said current-carrying electrodes of said first transistor in such a manner that said second transistor is conductive when said first transistor is nonconductive and is nonconductive when said first transistor is conductive; means for applying said alternating current ignition signals across said control electrode and a selected one of said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current ignition signal cycles and conductive during the other one-half cycle of each one of said alternating current ignition signals; first and second capacitors; first and second resistors; means for connecting the series combination of said first capacitor and said first resistor across said current-carrying electrodes of a selected one of said first and second transistors; means for connecting the series combination of said second capacitor and said second resistor across said current-carrying electrodes of the other one of said first and second transistors; third and fourth transistors each having two current-carrying electrodes and a control electrode; means for connecting said current-carrying electrodes of said third and fourth transistors in parallel across said direct current potential source; means for connecting said control electrode of a selected one of said third and fourth transistors to the junction between said first capacitor and said first resistor whereby said selected one of said third and fourth transistors is rendered conductive while said first capacitor charges when said selected one of said first and second transistors across the said currentcarrying electrodes of which said series combination of said first capacitor and said first resistor is connected is nonconductive; means for connecting said control electrode of the other one of said third aNd fourth transistors to the junction between said second capacitor and said second transistor whereby said other one of said third and fourth transistors is rendered conductive while said second capacitor charges when the other one of said first and second transistors across the current-carrying electrodes of which said series combination of said second capacitor and said second resistor is connected is nonconductive; and at least one common resistor included in said means for connecting said current-carrying electrodes of said third and fourth transistors in parallel across said direct current potential source across which an output signal appears while either one of said third and fourth transistors is conducting.

2. A circuit for producing two like polarity output signal pulses in response to each alternating current input signal cycle comprising in combination with a direct current potential source: first and second transistors each having two current-carrying electrodes connected in parallel across said direct current potential source and a control electrode; means for interconnecting said control electrode of said second transistor and one of said current-carrying electrodes of said first transistor in such a manner that said second transistor is conductive when said first transistor is nonconductive and is nonconductive when said first transistor is conductive; means for applying said alternating current input signals across said control electrode and a selected one of said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current signal cycles and conductive during the other one-half cycle of each one of said alternating current signals; third and fourth transistors each having two current-carrying electrodes connected in parallel across said source of direct current potential and a control electrode; output circuit means; first circuit means interconnected with said control electrode and a selected one of said current-carrying electrodes of a selected one of said third and fourth transistors and responsive to said first transistor becoming nonconductive for rendering said selected one of said third and fourth transistors conductive for a predetermined period of time for producing a first output signal across said output circuit means; and second circuit means interconnected with said control electrode and a selected one of said current-carrying electrodes of the other one of said third and fourth transistors and responsive to said second transistor becoming nonconductive for rendering said other one of said third and fourth transistors conductive for a predetermined period of time for producing a second output signal across said output circuit means.

3. A circuit for producing two like polarity output signal pulses in response to each cycle of an alternating current input signal cycle comprising in combination with a direct current potential source; first and second transistors each having two current-carrying electrodes connected in parallel across said direct current potential source and a control electrode; means for interconnecting said control electrode of said second transistor and one of said current-carrying electrodes of said first transistor in such a manner that said second transistor is conductive when said first transistor is nonconductive and is nonconductive when said first transistor is conductive; means for applying said alternating current input signals across said control electrode and a selected one of said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current signal cycles and conductive during the other one-half cycle of each one of said alternating current signals; third and fourth transistors each having two current-carrying electrodes conneCted in parallel across said source of direct current potential and a control electrode; output circuit means; a first R-C circuit connected across said current-carrying electrodes of said first transistor and interconnected with said control electrode and a selected one of said current-carrying electrodes of a selected one of said third and fourth transistors for rendering said selected one of said third and fourth transistors conductive when said first transistor becomes nonconductive for a predetermined period of time for producing a first output signal across said output circuit means; and a second R-C circuit connected across said current-carrying electrodes of said second transistor and interconnected with said control electrode and a selected one of said current-carrying electrodes of the other one of said third and fourth transistors for rendering said other one of said third and fourth transistors conductive when said second transistor becomes nonconductive for a predetermined period of time for producing a second output signal across said output circuit means.

4. A circuit for producing two like polarity output signal pulses in response to each cycle of an alternating current input signal cycle comprising in combination with a direct current potential source: first and second transistors each having two current-carrying electrodes connected in parallel across said direct current potential source and a control electrode; means for interconnecting said control electrode of said second transistor and one of said current-carrying electrodes of said first transistors in such a manner that said second transistor is conductive when said first transistor is nonconductive and is nonconductive when said first transistor is conductive; means for applying said alternating current input signals across said control electrode and a selected one of said current-carrying electrodes of said first transistor for rendering said first transistor nonconductive during a selected one-half cycle of each one of said alternating current signal cycle and conductive during the other one-half cycle of each one of said alternating current signals; first and second capacitors; first and second resistors; means for connecting the series combination of said first capacitor and said first resistor across said current-carrying electrodes of a selected one of said first and second transistors; means for connecting the series combination of said second capacitor and said second resistor across said current-carrying electrodes of the other one of said first and second transistors; third and fourth transistors each having two current-carrying electrodes and a control electrode; means for connecting said current-carrying electrodes of said third and fourth transistors in parallel across said direct current potential source. means for connecting said control electrode of a selected one of said third and fourth transistors to the junction between said first capacitor and said first resistor whereby said selected one of said third and fourth transistors is rendered conductive while said first capacitor charges when said selected one of said first and second transistors across the said current-carrying electrodes of which said series combination of said first capacitor and said first resistor is connected is nonconductive; means for connecting said control electrode of the other one of said third and fourth transistors to the junction between said second capacitor and said second transistor whereby said other one of said third and fourth transistors is rendered conductive while said second capacitor charges when the other one of said first and second transistors across the current carrying electrodes of which said series combination of said second capacitor and said second resistor is connected is nonconductive; and at least one common resistor included in said means for connecting said current carrying electrodes of said third And fourth transistors in parallel across said direct current potential source across which an output signal appears while either one of said third and fourth transistors is conducting.

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