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Publication numberUS3452731 A
Publication typeGrant
Publication dateJul 1, 1969
Filing dateOct 16, 1967
Priority dateOct 16, 1967
Publication numberUS 3452731 A, US 3452731A, US-A-3452731, US3452731 A, US3452731A
InventorsBecker Harry W
Original AssigneeMar Lin Safety Devices Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Ignition control circuit and power supply therefor
US 3452731 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Filed OCt. 16, 1967 July 1, 1969 H. W. BECKER IGNITION CONTROL CIRCUIT AND POWER SUPPLY THEREFOR Shet 2 0:2

AUXILIARY 56 f Q'TZ POWER SUPPLY 30 UNIT OSCOUT osc. IN T AUXILIARY POWER SUPPLY /50 6b UNIT (0) y/5C 56 /7 /7c 5; "Wv I 4U 40/ @J 0 ml 44 4c 4 i- /4 TRANS. a limes -iik-IGNIT. m /2 J SYSTEM L L-J C.D. SYSTEM United States Patent US. Cl 123-148 12 Claims ABSTRACT OF THE DISCLOSURE There is coupled between a battery and one end of the ignition coil of an ignition transformer, the transformer having connected to the other end thereof a set of interrupter contacts shunted by a capacitor, the rectified output of an oscillator energized from the battery. The AC output of the oscillator appears across the secondary winding of an oscillator output transformer to one end of which is coupled a first rectifier connected to said one end of the ignition coil and arranged normally to pass current from the battery. A second rectifier is connected between the other end of the secondary winding and the latter end of the ignition coil and arranged to pass current from the battery to said ignition coil in the same direction as the first rectifier and also to pass pulsating current in the same direction from the oscillator output.

Related application The application is a continuation-in-part of application Ser. No. 363,088, filed on Apr. 24, 1964, now abandoned.

Summary of prior art and invention This invention relates generally to power supply circuits having its principal, but not its only, application to ignition control circuits for internal combustion engines, and to a unique ignition control circuit including such power supply where the starting and/or running charac teristics of the engine are significantly improved.

A conventional form of ignition control circuit includes an ignition transformer having a primary coil (sometimes called an ignition coil) with one end connected to ground through a set of interrupter contacts which are periodically opened and closed by cams or the like coupled to the crankshaft of the automobile involved. A spark inhibiting capacitor is commonly connected across the interrupter contacts which forms a shock excitable resonant circuit with the primary coil when current flow is interrupted by opening of the contacts. The other end of the primary coil of the ignition transformer is connected to the storage battery of the automobile through a manually operable ignition switch operated by the vehicle operator and having off, run and start positions. When the manually operable ignition switch is turned to the start position, a starter relay is energized which connects a starter motor to the battery to initiate movement of the crankshaft and pistons of the automobile, and the battery is connected to the primary coil of the ignition transformer so current from the battery flows through the primary coil when the interrupter contacts are closed. The subsequent opening of the interrupter contacts collapses the field of the primary coil to induce a high voltage in a secondary coil of the ignition transformer which voltage is fed through the distributor to the spark plugs to generate sparks which ignite the gasoline in the cylinders of the engine. When the storage battery voltage is low, the energy delivered to the ignition transformer and to the spark plugs may be insufficient to start the engine. When the ignition switch is released from the start position it automatically moves to the run position where the starter relay is de-energized.

It is one of the objects of the invention to provide a relatively inexpensive unit insertable between the battery and the primary coil of the ignition transformer which materially increases the effective energy delivered to the primary coil of the ignition transformer so the engine can start under low battery voltage conditions. A related object of the invention is to provide a unit insertable between the battery and the primary coil of the ignition transformer which increases the effective power to the spark plugs during normal running operation of the automobile as well as during starting of the automobile.

Another and broader object of the invention is to provide a power supply unit which is energized from a battery and delivers to a load a substantially greater amount of power than the battery is capable of delivering by itself directly to the load.

A further object of the invention is to provide a power supply unit as described above which delivers an amount of power to the load in accordance with changes in the impedance of the load. A related object of the invention is to provide a power supply unit as just described used for delivering power to the primary coil of an ignition transformer of an internal combustion engine and wherein the variations in the reactance of the transformer caused by differences in the starter motor speed varies the power fed to the ignition transformer so that relatively larger amounts of power are delivered to the transformer during slower starting speeds than is delivered during faster starting speeds.

In accordance with one aspect of the invention, the power fed to an ignition circuit during starting of the engine includes, in addition to the steady direct current (DC) component from the storage battery, a much higher preferably pulsating DC booster voltage superimposed on the output of the storage battery. In such case, the normal steady DC voltage from the storage battery can be readily fed to the ignition transformer during the normal running of the engine by simply energizing the circuit generating the booster voltage through a circuit in parallel with the starter relay. Thus, when the ignition switch is released from the start position, the booster voltage generator automatically becomes de-energized leaving only the DC voltage from the battery as the source of current for the ignition circuit. The pulsating direct current component is obtained most advantageously from a booster voltage generating oscillator which, as above indicated, is energized from the storage battery when the ignition switch is operated to its start position. The output of the oscillator is most advantageously superimposed upon the output of the storage battery through an output transformer and a rectifier circuit which continuously allows current to flow from the storage battery to the ignition circuit and feeds to the ignition circuit rectified preferably pulsating current from the oscillator superimposed in additive relationship to the storage battery current.

When the ignition circuit is of the type where the interrupter contacts shunted by a capacitor are connected directly to the ignition coil, it is most advantageous that the oscillator be designed so that the operation thereof is correlated with the impedance of the ignition coil which impedance varies with the rate at which the engine is turned over by the starter motor, so that a larger amount of power is delivered to the ignition coil for lower starting speeds.

Other objects, advantages and features of the invention will become apparent upon making reference to the specification to follow, the claims and the drawings wherein:

FIG. 1 is a partial block diagram of a typical automative ignition system to which has been added an auxiliary power supply unit constituting the preferred form of the invention;

FIG. 2 is a circuit diagram of a test circuit setup for obtaining test data to evaluate the advantages of the invention;

FIG. 3 illustrates an exemplary manner in which the auxiliary power supply unit of the present invention is physically and electrically related to different forms of ignition control apparatus; and

FIG. 4 is a circuit diagram of the preferred oscillator and related circuitry of the auxiliary power supply unit of FIG. 1.

Detailed description of invention The invention is shown in the drawings embodied in a novel electrical control circuit especially suited for use with an ignition system of an internal combustion engine to insure optimum starting conditions of the engine under various types of adverse conditions.

The ignition system illustrated in the drawing includes a coil 2, which is the low voltage primary or ignition coil of a step-up ignition transformer 4 having a secondary coil 6 connected to the distributor and spark plugs 8 of the engine. The bottom or low voltage side of the primary coil 2 is connected in series with grounded interrupter contacts 13 shunted by the usual arc-inhibiting capacitor 11, which, contacts through a mechanical connection with the engine, are opened and closed alternately to complete and interrupt a circuit extending through the coil 2, a conventional type manually operated ignition switch 15 and the battery 14. The switch 15 shown has ganged electrically connected together movable poles 15a 15a respectively selectively engageable with off, run and start contacts 15b-15b', 15c15c and 15d-15a".

The switch poles 15c-15a are shown connected to the positive terminal of storage battery 14 and to the output of a voltage regulator 10 whose input is connected to the ungrounded terminal of a voltage generator 12. The opposite terminal of the generator 12 and the negative terminal of the battery 14 are grounded. The start contact 15d is connected to the ungrounded end of a starter motor relay 16' and to a load 17a extending from the auxiliary power supply unit 17 of the invention. The start contact 15d is connected to a lead 17b extending from the auxiliary power supply unit 17. The run contact 15c is connected to one end of a current responsive variable resistor 16 whose other end is connected to the lead 17b. (In a conventional ignition control circuit, the

latter end of the resistor 16 is connected directly to the high voltage side of the primary coil 2 of the ignition transformer 4.) in FIG. 1, the high voltage side of the primary coil 2 is connected to a lead 170 extending from the auxiliary power supply unit 17 When the switch 15 is in its start position, a motor starter relay 16' and lead 17a of the auxiliary power supply unit 17 connected to the switch contact 15d are connected by switch pole 15a to battery 14 to energize the unit 17 and to close contacts 16a of the relay 16 to energize a starter motor 19 .connected to the battery 14.

. Also, switch pole 15a will engage start contact 15d so battery 14 is connected directly to the lead 1711. When the switch 15 is in the run position, the battery 14 is coupled through switch pole 15a, contacts 150 and resistor 16 to the lead 17b. The resistor 16 is a conventional ballast resistor which varies the current conditions in the primary coil 2 in accordance with the speed of the motor. The resistor 16 has a resistance which varies in direct proportion to the current flowing therethrough. The resistor 16 is bypassed under starting conditions because a maximum spark voltage is needed under these conditions. The maintenance of high current and voltage conditions during normal operationof the engine would burn out the spark plug contacts. Thus, the resistor 16 is placed into the ignition circuit during running of the engine so that the current and voltage conditions of the spark are materially reduced to avoid spark plug wear. For similar reasons, the boost voltage supplied by the auxiliary power supply unit 17 is removed during running of the engine since the voltage booster action of the unit 17 is not needed during these conditions and the use of such a boost voltage would waste power and would reduce spark plug life.

As in the case of all conventional manually operable ignition switches 15, when the ganged switch poles 15a and 15a are moved into the start position they are movedagainst the restraining force of a spring which forces the poles into the run position of the switch. Thus, upon release of the ignition switch 15 from the start position, the poles 15a and 15a are automatically moved to the run position thereof where the poles 15a and 15 are respectively in contact with the run switch contacts 15c and 150. As is conventional in the run position of the switch 15, the starter relay 16' is disconnected from the battery 14. Also, the lead 17a extending from the auxiliary power supply unit 17 will then be disconnected from the battery 14 so that the auxiliary power supply unit 17 is de-energized.

As will appear, in the start position of the switch 15, the auxiliary power supply unit 17 superimposes upon the output of the battery 14 a pulsating direct current of the same polarity as the direct current flowing into the primary coil 2 from the battery 14. To this end, the lead 17a is connected to an oscillator 18 in the auxiliary power supply unit 17 so that the oscillator is energized by its connection to the battery in the start position of the switch 15. The output of the oscillator 18, which is an alternating voltage, is fed to one or more primary windings of an oscillator output transformer 20 which has a secondary winding 22. The bottom end of the secondary winding 22 is connected to the lead 17b and is coupled to an output lead through a rectifier 24 oriented to pass current from the battery 14 to the lead 170. For reasons to be explained, the rectifier 24 is shunted by a resistor 26. The output lead 170 is connected to the high voltage end of the primary coil 2 of the ignition transformer 4.

The upper end of the secondary winding 22 of the oscillator output transformer 20 is coupled through a rectifier 28 to the output lead 170. The rectifier 28 is arranged to pass current from the battery 14 to the output lead 17c and to pass the alternate half cycles of current resulting from the oscillator output where the upper end of the secondary winding is positive with respect to the bottom end thereof, that is when the oscillator output adds to the battery voltage. When the voltage across the secondary winding 22 opposes the voltage on the battery 14, the rectifier 28 becomes non-conductive and only the voltage and current from the battery 14 is coupled through the rectifier 24 to the output lead 170.

The root mean square value of the voltage induced into the secondary winding 22 is much larger than the voltage of the battery 14 which is typically from 6 to 12 volts. For example, this voltage advantageously has a value of from 15,000 to 30,000 volts. This produces much greater current flow in the primary coil 2 of the ignition transformer than is possible with the use of the battery 14 alone.

During start and run operation, when the circuit through the ignition coil 4 and the battery '14 is completed by closing of the interrupter contacts 13, energy from the battery is stored in the ignition transformer 4. Upon opening of the interrupter contacts 13, this energy is released at the higher voltage of the secondary winding 6 and is delivered through the distributor to one of the spark plugs of the engine. As is well known, the distributor operates in timed relation to the opening and closing of the interrupter contacts to connect the spark plugs one at a time and successively to the secondary winding of the transformer for the discharge of the stored energy to each plug to ignite fuel in the associated cylinder at the proper time in the engine cycle to produce a power stroke of the piston and cause continued operation of the engine. When the flow of current through the primary coil 2 is interrupted, current continues to flow through the primary coil 2 and the capacitor '11 charges up. The capacitor 11 is a conventional arc inhibiting capacitor which may, for example, be .25 microfarad.

A resistor 26 across rectifier 24 provides a discharge path for capacitor 11 so that the capacitor 11 will substantially fully discharge before the interrupter contacts 13 reclose, thereby preventing possible arcing of the contacts 13 during contact reclosure. For example, in one case, where the capacitor 11 was .25 microfarad and the inductance of the primary coil 2 was .007 henries, the resistor 26 was 33 ohms.

The advantages of the present invention under both starting conditions was proven by use of a test circuit like that shown in FIG. 2 (to which reference is now made) from which spark duration tests data was obtained under various conditions. (Generally, the longer the spark duration the more efiicient is the gasoline ignition.) As there shown, a switch 30 was connected between the lead 17a extending from the auxiliary power supply unit 17 and the battery 14 so that the opening of the switch 30 will render the oscillator 18 inoperative as in the case where the ignition switch 15 in FIG. 1 is in the run position. The interrupter contacts 13 and the capacitor 11 were connected to the bottom end of the coil 2 as in the case of FIG. 1. For convenience, the bottom terminal of the secondary coil 6 of the transformer 4 was connected through a low resistance connection 33 to the bottom terminal of the primary coil 2. The upper end of the secondary coil 6 was connected to a resistor-capacitor network including a series of resistors 35, 37 and 38 connected between the upper end of the secondary coil 6 and ground. The network further includes a capacitor 42 connected in parallel with the resistor 35, a capacitor 44 connected between the upper and lower ends, respectively, of the resistors 37 and 38, and an oscilliscope unit 40 connected across the resistor 38. The test spark plug 8' was connected between the upper end of the coil 6 and ground. A variable speed test motor 42 was connected to the interrupter contacts 13 to vary the interruption speed thereof.

The values of the various resistors and capacitors in the network referred to were as follows:

Resistor ohms 35500,000 Resistor do 37400,000 Resistor do 38100,000 Capacitor picofarads 42-100 Capacitor -1 do 44-100 In one test, spark duration times were measured by examining the traces on the face of the oscilliscope unit 40 with the auxiliary power supply unit completely out of the circuit, that is with the switch 330 opened. Spark duration times were also determined with the full auxiliary power supply unit 17 in the circuit, by closing the switch 30.

With the motor 42 operating at a speed of 1000 revolutions per minute, the spark duration times obtained in the test were 1.2 milliseconds when the auxiliarypower supply units 17 was completely out of the circuit, 1.6 milliseconds When only the rectifier 24 and resistor 26 were in the circuit and 2.5 milliseconds when the entire auxiliary power supply unit 17 was in the circuit.

Refer to FIG. 3 which illustrates the manner in which the auxiliary power unit '17 is most conveniently and physically connected to the ignition transformer 4. The ignition transformer 4 generally comprises a casing 4a having a screw terminal 4b connected to what is the upper end of the primary coil 2 in FIG. 1, a screw terminal 4c which is connected to what is the bottom end of the primary coil in FIG. 1, and an output terminal 4d which corresponds to the end of the secondary coil 6 in FIG. 1

which extends to the distributor and spark plugs 8. An

insulating terminal strip 41 having a hollow terminal 41a and a screw terminal 41b at opposite ends thereof is attached to the terminal 411 of the ignition transformer 4 by slipping the hollow terminal 41a over the terminal 4b and anchoring the same thereover together with the end of lead by a suitable nut. The terminal 41b forms a convenient point for connection of the lead 17b extending from the auxiliary power supply unit 17 and a conductor 17b which, before the connection of the present invention, extended to the ignition transformer terminal 4b from the ballast resistor '16.

As previously indicated, the auxiliary power supply unit 17 acts as a very effective booster circuit for loads other than the ignition transformer 4. To this end, as exemplified by the dashed line circuits in FIG. 3, the auxiliary power supply unit 17 may be connected to a conventional transtisor ignition unit 4a or to a capacitor discharge unit 4a by means of the insulator terminal strip 41 as described.

A specific aspect of the invention relates to the design of the oscillator 18, and so reference should now be made to FIG. 4 which shows the complete circuitry of the power supply unit 17. The oscillator 18 most advantageously is one wherein the energy transferred to the ignition transformer through the rectifier 28 is controlled in response to changes in the engines speed so that a greater quantity of the energy is added to that of the battery when the engine speed is low as occurs with low battery power. This is accomplished as a result of recognizing that the reactance of the ignition transformer coil changes with the engine speed and that this reactance change may be utilized to vary the frequency of the oscillator 18.

The oscillator 18 includes a capacitor 50 forming part of a resonant tank circuit for the oscillator which circuit also includes winding 52, 52' and 52" of the oscillator output transformer 20. The oscillator 18 further includes a PNP junction type transistor 54 having a base electrode 54a, an emitter electrode 54b and a collector electrode 540. The collector electrode 540 is grounded through a conductor 56 and the emitter electrode is coupled to one of the tank circuit winding 52 whose other end is connected to the lead 17aand coupled to the positive terminal of the battery 14 through the switch 15. The oscillator 18 oscillates by virtue of the windings 52' and 52 which form feedback windings coupled to the base electrode 54a of the transistor through capacitor 58.

A bias circuit is connected between the base and emitter electrodes 54a and 54b to bias the transistor 54 to cut off over more than half of each cycle of oscillation and thereby achieve a Class C type of operation. This circuit includes a rectifier 60 coupled between the base-collector electrodes 54a and 54b. A resistor 62 preferably is connected in series with the rectifier 60 to increase the cut-off or back bias on the transistor. Means is provided to protect the transistor from damage due to large voltages which may develop in the transformer 20. While a capacitor may be utilized for this purpose, a resistor 64 is used instead connected directly between the collector and emitter electrodes 54c and 54b.

To insure operation of the transistor even at low temperatures, a resistor 68 preferably is connected directly be tween the collector and base electrodes 54c and 54a. A transistor found to operate more particularly satisfactorily is Model 2N1557 manufactured by Motorola Semiconductor Products, Incorporated, of Phoenix, Ariz. The resistance values found to be suitable in the exemplary circuit describedare 1000 ohms for the resistor 68 between the collector and the base electrodes 330 ohms for the resistor 64 between the collector and emitter electrodes and 3.3 ohms for the resistor 62 in series with the bias diode 60, the latter being a 750 milliampere Top Hat diode. The value of the capacitor 58 may be 12 microfarads.

The transformer 20 preferably comprises two bifilar windings with windings 52 and 52" formed by one of the bifilar windings and windings '52 formed by part of the other bifilar winding connected in series aiding relation across the tank capacitor 50 and with the secondary winding 22 formed by the rest of the other bifilar winding. Although an air core for the transformer may be used, the windings in the present instance preferably have a magnetic core in the form of an iron bar. This arrangement has been found to provide the desired sensitivity of the oscillator to variations in the reactance of the ignition transformer as well as maintaining self-excitation of the oscillator. In the present instance, each of the windings 52 and 52" formed by one of the bifilar windings has 16 turns and each of the windings 52' and 22 formed by the other bifilar winding has 34- turns. Using No. 18 wire, this provides a primary inductance in the transferomer 20 on the order of 250 microhenries. The capacitor 50 used in the examplary circuit has a capacitance of 4 microfarads, providing an oscillating frequency in the audio frequency range on the order of 5000 cycles per second.

When the switch is in its start position, and the engine cranking speed is very slow with a correspondingly slow rate of opening and closing of interrupter contacts 13, the core of the ignition transformer tends to become saturated so the primary coil 2 has a relatively low inductance reactance. This low reactance is reflected through the oscillator output transformer 20 as a low capacitive reactance. The resistance of the primary coil 2 as reflected through the transformer 20 appears relatively large in comparison with the direct current resistance of the windings 52, 52 and 52 with the result that little power is absorbed in the resonant circuit of the oscillator and most of the power resulting from the oscillations is transmitted to the ignition transformer 4.

As the frequency of the interrupter contacts 13 increases, for example, as would occur when the battery is strong enough to produce a normal starting speed of the engine, the inductance of the primary coil 2 increases because the core of the ignition transformer 4 no longer is saturated or is less saturated than before. Because of this and the increased frequency, the inductive reactance of the coil increases. This is reflected as a higher capacitive reactance in series with the windings 52, 52 and 52" to cause an increase of the frequency of the oscillator and a correspondingly greater circulating current in the resonant circuit of the oscillator. The resistance of the primary coil 2 reflected through the transformer now appears relatively small in comparison to the windings 52, 52' and 52" with a correspondingly greater absorption of power in the resonant circuit of the oscillator and less power supplied to the ignition transformer.

It will be apparent that the novel ignition control circuit described above delivers higher more effective currents and power to the ignition transformer resulting in higher and more sustained sparks in the spark plugs and better starting and lower gas consumption. This is achieved with few parts and at a modest cost. With the particular oscillator described, a high efficiency Class C operation is obtained at frequencies which are in the audio frequency range. By virtue of the novel rectifier circuit including rectifiers 24 and 28, the voltage and current from the auxiliary power supply unit is added to that of the battery for simultaneous application to the load for starting and the battery voltage is applied more efiectively during running operation when the oscillator 18 is inoperative because of the presence of rectifier 24. Whereas in this instance, the reactance of the load varies with different operating conditions, such variations are utilized conveniently to control the amount of power delivered by the auxiliary power supply unit during starting of the engine, so maximum energy delivery occurs when it is needed the most, that is, when engine cranking speed is low. Even at higher cranking speeds, however, some power from the auxiliary power supply unit is delivered to the ignition transformer to supplement the power delivered by the battery.

It should be understood that numerous modifications can be made in the most preferred form of the invention 8 described above without deviating from the broader aspects therein.

1 claim:

1. In a power supply circuit comprising a battery and a booster circuit connected in series with said battery, said booster circuit comprising an oscillator producing a pulsating output energized from said battery and having an output circuit including the primary winding of an output transformer across which said pulsating output appears, the improvement comprising a first rectifier coupled between an output conductor and said battery to pass current from said battery in one direction to said output conductor, there being substantially no voltage dropping and power consuming resistors between said battery and output conductor so the voltage at said output conductor contributed by said battery is about the same voltage as the output of the battery, a second rectifier connected in series with a secondary winding of said output transformer across which secondary winding the pulsating oscillator output appears, the series circuit of said second rectifier and said secondary winding being continuously coupled during operation of the booster circuit across said first rectifier, and said second rectifier being oriented to pass current from said battery to said output conductor in the same direction as said first rectifier and also to pass current in the same direction to said output conductor resulting from the oscillator output voltage induced in said secondary winding of said output transformer so the voltage output of the battery and the rectifier output of the oscillator will be in additive relation when said second rectifier is conducting.

2. The power supply circuit of claim 1 in combination with an ignition system for an internal combustion engine having spark plugs comprising: an ignition transformer having a primary coil and a secondary coil magnetically coupled to said primary coil for applying a high voltage to the spark plugs and into which an ignition voltage is induced when current tfiOW in said primary coil is interrupted, said output conductor of said power priply circuit being connected to one terminal of said primary coil, wherein said battery and oscillator supply current thereto when permitted to do so, and switch means connected to the other terminal of said primary coil and adapted to be intermittently operated to open and close the citcuit to cause alternate storage and release of energy by said ignition transformer to induce a firing voltage in the secondary coil thereof.

3. The combination of claim 2 wherein said oscillator generates an alternating current voltage fed in rectified form to said primary coil through said output transformer and one of said rectifiers which rectified voltage is superimposed on the steady direct current voltage of the battery.

4. In an ignition system for an internal combustion engine which circuit includes a battery, an ignition circuit to be energized from said battery, said ignition circuit including an ignition coil, and switch means coupled to said ignition coil and adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy in said ignition coil as current is intermittently established and interrupted in said ignition coil, the improvement comprising: an oscillator for generating pulses of alternating current in its output, and means including rectifier means connecting said battery and the output of the oscillator in series, voltage adding relationship with said ignition circuit for delivering a voltage to the ignition circuit which is the sum of the battery voltage plus the rectified unfiltered pulsing oscillator output.

'5. In an ignition system for an internal combustion engine which system includes a battery, an ignition circuit to be energized from said battery, said ignition circuit including an ignition coil, switch means adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy in said ignition coil as current is intermittently established and interrupted in said ignition coil, the improvement comprising: boost voltage generator means coupled between said battery and ignition circuit and energized from said battery for providing a boost voltage of the same polarity as, and superimposed upon, the direct current voltage from said battery, and manually operable ignition switch means having a start position where said boost voltage generation means is connected to said battery to energize the same and a run position where said battery is disconnected from said boost voltage generator means to de-energize the same so that only the output of the battery is fed to that ignition circuit.

6. In an ignition system for an internal combustion engine having spark plugs which system includes a battery, an ignition transformer having a primary coil for applying a high voltage to the spark plugs and into which an ignition voltage is induced when current flow in said primary coil is interrupted, and an ignition circuit including said primary coil connected in series with said battery and a pair of contacts adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy by said transformer as current flow is intermittently established and interrupted, the improvement comprising: a first rectifier connected in series with said ignition circuit and poled to pass current from said battery in one direction, an oscillator having an output circuit including the primary winding of an output transformer and providing a pulsating output voltage and a second rectifier continuously connected during initiation of ignition in series with a secondary winding of said output transformer across said first rectifier, said second rectifier being poled to pass current from said battery in the same direction as said first rectifier and to couple to the primary coil of the ignition circuit the pulsating oscillator output voltage induced into the secondary winding of said transformer in voltage additive relationship to the output of said battery when the second rectifier is conductive.

7. In an ignition system for an internal combustion engine which system includes a source of power, an ignition transformer having a primary coil, an ignition circuit including said primary coil connected in series with said source and a pair of contacts adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy by said transformer, and a capacitor connected across said contacts, the improvement comprising: a first rectifier connected in said ignition circuit and poled to pass current from said source in one direction, a transistor amplifier having a bias circuit normally biasing the transistor to cut off for more than half of each cycle of operation, an output circuit including said source and the primary of an output transformer, a capacitor connected across said output transformer primary to form a tank circuit, and a feedback coupling between said output primary and input terminals of said transistor, a second rectifier connected in series with a secondary of said output transformer across said first rectifier, said second rectifier being poled to pass current from said source in the same direction as said first rectifier, and switch means for closing said ignition circuit and completing said output circuit through said source, said output transformer primary and said capacitor in said tank circuit having capacitance and inductance values correlated with the inductance of said ignition primary coil to control the delivery to said ignition coil of energy stored in the tank circuit and to cause a large amount of such energy to be delivered to supplement the power from said source when the engine cranking speed is low.

8. In an ignition system for an internal combustion engine which system includes a source of power, an ignition transformer having a primary coil, an ignition circuit including said primary coil connected in series withsaid source and a pair of contacts adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy by said transformer, and a capacitor connected across said contacts, the improvement comprising: a first rectifier connected in said ignition circuit and poled to pass current from said source in one direction, a transistor amplifier having a bias circuit normally biasing the transistor to cut off for more than half of each cycle of operation, an output circuit including said source and the primary of an output transformer, a capacitor connected across said output transformer primary to form a tank circuit, and a feedback coupling between said output primary and input terminals of said transistor, a second rectifier connected in series with a secondary of said output transformer across said first rectifier, said second rectifier being poled to pass current from said source in the same direction as said first rectifier, and switch means for closing said ignition circuit and completing said output circuit through said source, said amplifier being responsive to variations in the inductive reactance of said ignition primary coil and opearting to supply a large amount of power to said ignition circuit to supplement the power from said source when the engine cranking speed is low and such reactance is correspondingly low.

9. In an ignition system for an internal combustion engine which system includes a source of power, an ignition transformer having a primary coil, an ignition circuit including said primary coil connected in series with said source and a pair of contacts adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy by said transformer, and a capacitor connected across said contacts, the improvement comprising a first rectifier connected in said ignition circuit and poled to pass current from said source in one direction, a transistor amplifier having an output circuit including said source and the primary of an output transformer, a capacitor connected across said output transformer primary to form a tank circuit, and a feedback coupling between said output primary and input terminals of said transistor, a second rectifier connected in series with a secondary of said output transformer across said first rectifier, said second rectifier being poled to pass current from said source in the same direction as said first rectifier, and switch means for closing said ignition circuit and completing said output circuit through said source, said amplifier being responsive to variations in the reactance of said ignition primary coil and operating to supply a large amount of power to said ignition circuit when the engine cranking speed is low and such reactance is correspondingly low.

10. In an ignition system for an internal combustion engine including a source of power, an ignition transformer having a primary coil, an ignition circuit including said primary coil connected in series with said source and a pair of contacts adapted to be closed and opened intermittently at a rate correlated with the speed of said engine to cause alternate storage and release of energy by said transformer, and a capacitor connected across said contacts, the improvement comprising a first rectifier connected in said ignition circuit and poled to pass current from said source in one direction, a transistor amplifier having a bias circuit normally biasing the transistor to cut 01$ for more than half of each cycle of operation, an output circuit including said source and the primary of an output transformer, a capacitor connected across said output transformer primary to form a tank circuit, and a feedback coupling between said output primary and input terminals of said tarnsistor, a second rectifier connected in series with a secondary of said output transformer across said first rectifier, said second rectifier being poled to pass current from said source in the same direction as said first rectifier and said amplifier being r 1 1 responsive to variations in the inductive reactance of said ignition primary coil and operating to supply a large amount of power to said ignition circuit to supplement the power of said source when the engine cranking speed is low and such reacta'nce is correspondingly low.

11. An ignition system for an internal combustion engine including a source of power, an ignition transformer having a primary coil, an ignition circuit including said primary coil connected in series with said source and a pair of contacts adapted to be closed and opened intermittently'at arate correlated with the speed of said engine to cause alternatestorage and release of energy by said transformer, and a capacitor connected across said contacts, improvements comprising a first rectifier connected in said ignition circuit and poled to pass current from said source in' one direction, a transistor amplifier having an output'circuit including said source and the primary of an output transformer, a capacitor connected across said output transformer prirnar'yto form a tank circuit, and a feedback coupling between said output primary andinput terminals of said transistor, and a second rectifier connected in series with a secondary of said output transformer across said first rectifier, said second rectifier being poled to pass current from said source in the same direction as said first rectifier, and said 25 amplifier being responsive to variations in the inductive References Cited UNITED STATES PATENTS 2,883,560 4/1959 Knudsen.

3,018,413 1/ 1962 Neapolitakis.

3,170,451 2/ 1965 Fortien.

3,175,123 3/1965 Dilger.

3,184,640 5/1965 Jukes.

3,026,863 3/1962 Reynolds etal. 123148- 3,047,728 7/1962 Martin 3071() 3,059,148 10/1962 Barker 315206 3,241,538 3/ 1966 Hugenholtz.

3,280,809 10/ 1966 Issler.

LAURENCE M. GOODRIDGE, Primary Examiner;

11.5. C1. X.R. 3 l5209

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3620200 *Jul 8, 1969Nov 16, 1971Ambac IndBooster circuit for ignition systems
US4176647 *Jul 5, 1977Dec 4, 1979Gerry Martin EModulation ignition system
US4207851 *Apr 25, 1978Jun 17, 1980Crisefi Charles JEmergency ignition for internal combustion engines
US4528972 *Oct 31, 1983Jul 16, 1985Beaumont P DeEmergency ignition device for thermal engines with controlled ignition
US7291934Aug 30, 2005Nov 6, 2007Caterpillar Inc.Machine with an electrical system
DE4406830A1 *Mar 2, 1994Sep 7, 1995Spindler Bernhard Dipl IngControl of ignition energy for car engine spark plugs
DE4406830C2 *Mar 2, 1994Dec 3, 1998Spindler Bernhard Dipl IngSchaltungsanordnung zum Steuern und Regeln der ZŁndenergie von ZŁndfunken bei ZŁndkerzen von Brennkraftmaschinen
WO1997026455A1 *Jan 16, 1997Jul 24, 1997Unison IndMagneto-based ignition system
Classifications
U.S. Classification123/623, 123/641, 315/209.00R
International ClassificationF02P15/00, F02P15/12
Cooperative ClassificationF02P15/12
European ClassificationF02P15/12