US3587551A

US3587551A - Electronic iginition circuit

Info

Publication number: US3587551A
Application number: US771526A
Authority: US
Inventors: Charles Richard Harrow
Original assignee: Solitron Devices Inc
Current assignee: Solitron Devices Inc
Priority date: 1968-10-29
Filing date: 1968-10-29
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28

Abstract

AN ELECTRONIC IGNITION CIRCUIT IN WHICH AN ELECTRIC PULSE PRODUCED BY A MAGNETIC PICKUP DISTRIBUTOR IS UTILIZED TO

TRIGGER A POWER CIRCUIT TO CHARGE AND FREE AN IGNITION COIL.

Description

United States Patent Charles Richard Harrow Sayreville, NJ.

Oct. 29, 1968 June 28, 1971 Solitron Devices, Inc. Tappan, N.Y.

Inventor Appl. No. Filed Patented Assignee ELECTRONIC IGNITION CIRCUIT 2 Claims, 3 Drawing Figs.

US. Cl 123/148E, 315/209 Int. Cl F02p 3/02 Field of Search 123/148 (B), 148 (E), 148 (DC), 148 (AC); 315/209,209

[51' I 21vn| 3RD I 4 STAGE ISTAGE] SIAGE I STAGE l I References Cited UNITED 5/1966 Konopa STATES PATENTS ort et a1.

hneider et a1.

1/1968 Kasama et a1 Primary Examiner- Laurence M. Goodridge Att0rneyBernard Malina, Esq.

l23/l48E l23/I48E 123/148E 123/148E ABSTRACT: An electronic ignition circuit in which an electric pulse produced by a magnetic pickup distributor is utilized to trigger a power circuit to charge and fire an ignition coil.

5T1! STAGE TO I lll' SBUIKPLUGS PATENTEDJUH28 I97] SHEET 1 BF 3 I ul wm u fi w J w N NN QM mn II R N I w. m W FM mfi mam Q 1 mm .5 MN kw J Q ma NT, w Q QM mm v. M N n ,k R Q .MPIITLTIFIIRPIIII INVENTOR. CHARLES RICHARD HARROW ATTORNEY ELECTRONIC IGNITION CIRCUIT BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to ignition systems for internal combustion engines and more particularly to transistorized ignition systems for internal combustion engines.

2. Description of the Prior Art Various types of transistorized ignition systems have been proposed in the past. One of the difficulties has been assuring that the ignition coil was charged at the proper time. Excitation was provided by breaker points which required precise adjustment. Further they were subject to wear and pitting by arcing during the opening of the points. The present invention provides means for insuring the charge to the ignition coil at the proper time and replaces the movable points with stationary coils.

SUMMARY An electronic ignition system in which an electric pulse from a magnetic pickup distributor is rectified, regulated and amplified to trigger a power circuit to energize and fire an ignition coil.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of a system embodying the invention.

FIG. 2 is a schematic diagram of a modification of the embodiment of FIG. 1.

FIG. 3 is a schematic diagram of a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 of the drawings, a magnetic pickup distributor 1 includes a PM rotor 2 and a plurality of pickup coils 3. While six pickup coils have been illustrated and described, it is understood that the number will be that of the number of cylinders of the internal combustion engine on which it is to be used. The magnetic pickup distributor is connected to be driven by the engine in synchronism with a distributor 4 as indicated by'a dashed line. The distributor 4 includes a movable contact 5 and stationary contacts 6 which connect to spark plugs (not shown).

The pickup coils 3 have one side connected by conductor 7 to ground and the other sides are connected by conductor 8 to a diode 9 in the first stage of the ignition circuit. The diode 9 is connected by resistor 10 and conductor 11 to base 12 of a transistor 13. The transistor 13 has an emitter 14 connected by resistor 15 and conductor 16 to a conductor 17 which is connected by resistor 18 and conductor 19 to one side of a battery 20. Also the transistor 13 has a collector 21 connected by resistor 22 and conductor 23 to conductor 24 which is connected to ground. A Zener diode 25 is connected by conductor 26 between the conductors 17 and 24. A resistor 27 is connected between the conductors l1 and 17. A resistor 28 is connected between the

conductors

11 and 24 as is a capacitor 29.

The collector 21 of the transistor 13 is also connected by conductor 30 to base 31 of a transistor 32 in the second stage of the ignition circuit. The transistor 32 has an emitter 33 connected by resistor 34 to the conductor 24 and a collector 35 connected by resistor 36 to the conductor 17. Also the collector 35 is connected by conductor 37 to base 38 of a transistor 39 in the third stage. The transistor 39 includes an emitter 40 connected by conductor 41 to emitter 42 of a transistor 43. Collector 44 of transistor 39 is connected by conductor 45 and resistor 46 to the conductor 17. Also the collector 44 is connected by resistor 47 to base 48 of the transistor 43. A diode 49 is connected between the conductor 41 and the conductor 24. The transistor 43 has a collector 50 connected by 'resistor 51 to the conductor 17 and its base 48 is connected by resistor 52 to the conductor 24.

A transistor 53 in stage 4 has a base 54 connected by diode 55 to the collector 44 of the transistor 39. The transistor 53 has an emitter 56 connected by a diode 57 and resistor 58 to the conductor 24. A resistor 57A is connected across the diode 57. The transistor 53 also has a collector 59 connected by resistor 60 to the conductor 19 and also connected by resistor 61 to base 62 of a transistor 63. The transistor 63 includes an emitter connected by conductor 64 to the conductor 19 and a collector 65 connected by conductor 66 to base 67 of a transistor 68 in stage 5.

A Zener diode 69 is connected between the conductor 66 and the conductor 19. Also a resistor 70 is connected between the

conductor

66 and 19. The transistor 68 has an emitter 71 connected to the conductor 19 by a resistor 72 and a collector 73 connected to base 74 of a transistor 75. The transistor 75 has an emitter 76 connected to base 77 of a transistor 78 and also is connected by resistor 79 to the conductor 24. Also the transistor 75 has a collector 80 connected to collector 81 of the transistor 78 and the

collectors

80 and 81 are connected by conductor 82 to the conductor 19. Emitter 83 of the transistor 78 is connected by resistor 84 to the conductor 24 and is also connected to base 85 of a transistor 86 in the output stage.

The transistor 86 has a collector 87 connected by resistor 88 to the conductor 19 and an emitter 89 connected by conductor 90 to base 91 of a transistor 92. Also the emitter 89 is connected by resistor 93 to the conductor 24 and also by resistor 94 to the base 67 of the transistor 68. Diodes 95 are connected between the

conductors

90 and 24 and diode 96 is also connected between the

conductors

90 and 24 with the polarity opposite of .that of the diodes 95. The transistor 92 has an emitter 97 connected by resistor 98 to the conductor 24 and a collector 99 connected to one side of primary winding 100 of an ignition coil 101. The other side of the winding 100 is connected to conductor 19. A capacitor 102 is connected across the winding 100.

The ignition coil 10] has a secondary winding 103 one side of which is common to the primary 100. The other side of the winding 103 is connected by conductor 104 to the movable contact 5.

In the operation, the electric pulse produced by the magnetic pickup distributor 1, which is synchronized with the distributor 4 to provide the pulse at the proper time, is rectified and amplified by the first two stages of the circuit. The rising portion of the electric pulse fires the third stage, Schmitt trigger circuitry, which turns on the other stages to charge the ignition coil. The falling portion of the pulse resets the Schmitt trigger which turns off the output and thus discharges the coil through the distributor to a predetermined spark plug. The first three stages are regulated to a predetermined voltage by the Zener diode 25, for example in a l2 volt system to 3.9 volts.

The fourth stage acts as a level shifter and switch for the fifth stage regulator circuitry. This stage limits the drive current to the output transistor 92 and enables it to operate in its active region. This eliminates the need for a voltage dropping ballast resistor. The output stage turns on the output transistor 92 to connect the battery 20 to charge the ignition coil and also provides protective circuitry that enables the output transistor 92 to discharge the ignition coil without failure. The capacitor 102 tunes the primary winding of the ignition coil and provides a capacitive load for the output transistor 92.

Reference is now made to FIG. 2 of the drawing, wherein like parts have been assigned the same reference numerals as in FIG. 1, in which the first stage has been modified from that shown in FIG. 1. A magnetic pickup distributor has one side of a winding 3 connected by a resistor 105 to the conductor 17. The other side of the winding 3 is connected by resistor 106 and conductor 107 to base 12 of a transistor 13. A capacitor 29 is connected between the conductor 17 and the conductor [07 and a resistor 108 is connected between the conductor 107 and conductor 24. The transistor 13 has an emitter 14 connected to the conductor 17. Also the transistor 13 has a collector 21 connected by

resistors

109 and 22 and conductor 23 to the conductor 24. The junction point between the resistors 28 and 109 is connected by conductor 30 to the base 31 of transistor 32 in the second stage.

The remainder of the circuits are the same as described for I FIG. 1, hence a detailed description will be omitted to avoid duplicity. The first stage has been modified to improve the overall performance of the circuit. The input signal from the magnetic pickup 1 is now connected between the positive supply voltage and the base of the first transistor 13. This enables the first stage to be triggered off the negative portion of the input signal, thus improve the ignition timing requirement. The bias for the first stage has been adjusted for the aforenoted change. The remainder of the circuits operate as set forth for FIG. 1.

Reference is now made to FIG. 3 which illustrates a different embodiment that requires fewer components. A magnetic pickup 111 has a permanent magnet rotor 112 and an output winding 113. One side ofthe winding 113 is connected by conductor 114, resistor 115 and conductor 116 to the positive side of a battery 117. The negative side of the battery 117 is connected to ground. The other side of the winding 113 is connected by resistor 118 and conductor 119 to base 120 of a transistor 121. A capacitor 122 is connected between the

conductors

114 and 119. The transistor 121 has an emitter 123 connected to the conductor 114. Also the transistor 121 has a collector 124 connected by resistor 125 and conductor 126 to base 127 of a transistor 128 in stage two. A Zener diode 129 is connected by conductor 130 between the conductor 114 and a conductor 131 which is connected to ground.

The transistor 128 has an emitter 132 which is connected by conductor 133 to the conductor 131. A collector 134 of the transistor 128 is connected by resistor 135 to the conductor 114. Also the collector 134 of the transistor 128 is connected to base 136 ofa transistor 137. The transistor 137 has a collector 138 connected by a resistor 139 to the conductor 114. The transistor 137 has an emitter 140 connected by resistors 141 and 142 to the conductor 131. The junction point between the resistors 141 and 142 is connected by conductor 143 and resistor 144 to the conductor 126.

The emitter 140 of the transistor 137 is also connected by resistor 145 to base 146 of transistor 147 in the third stage. The transistor 147 has an emitter 148 connected by

diodes

149 and 150 to the conductor 131 and also a collector 151 connected by resistor 152 to the conductor 116.

The collector 151 of the transistor 147 is also connected by conductor 153 to base 154 of a transistor 155 in the fourth stage. The transistor 155 has an emitter 156 connected by resistor 157 to the conductor 131 and a collector 158 connected by conductor 159 to the conductor 116. Also the emitter 156 of the transistor 155 is connected to base 160 of a transistor 161 which has a collector 162 connected to the conductor 159. The transistor 161 has an emitter 163 connected by conductor 164 to collector 165 of a transistor 166 in the fifth stage.

The transistor 166 has an emitter 167 connected by conductor 168 to the conductor 131 and also a base 169 connected by conductor 170 to emitter 171 of a transistor 172 in the output stage. The emitter 171 is also connected by resistor 173 to the conductor 131. A resistor 174 is connected between the conductor 164 and the conductor 131 as is a diode 175. The transistor 172 has a base 176 connected by the conductor 164 the distributor, and is triggered to the collector 165 of the transistor 166. Also the transistor 172 has a collector 177 connected by conductor 178 to one side of primary winding 179 of ignition coil 180. The other side of the primary winding 179 is connected by conductor 181 to the conductor 116. The coil 180 has a secondary winding 182, one end being in common with the primary winding 179 and the other end connected to a distributor. A capacitor 183 is connected across the primary winding 179.

In the operation, the first stage senses the input signal produced by the magnetic pickup, which is synchronized with by the negatively going portion of this signal. The capacitor 22 furnishes t e necessary frequency compensation to provide stability. The signal from the first stage in turn triggers the two stage saturating amplifier of the second stage. The Zener diode 129 regulates the voltage, for example to 6.2 volts, and the resistor 115 limits the current. The switching levels of the second stage are shifted by the third stage transistor network, the output of which supplies the drive current for the fourth stage which drives the output transistor to charge the primary of the ignition coil. The fifth stage transistor limits the charging current to a predetermined value, for example 5 amps, by bypassing the base drive to the output transistor when the predetermined level is reached. The capacitor 183 tunes the primary of the ignition coil and presents a capacitive load line for the output transistor. The diode protects the emitter-base junction of the output transistor 172 against any reverse bias.

Although several embodiments of the invention have been illustrated and described, various changes in the form and relative arrangement of the parts which will now appear to those skilled in the art, may be made without departing from,

the scope of the invention.

lclaim:

1. An electronic ignition circuit comprising an ignition coil having a primary and a secondary winding, a distributor connecting said secondary winding to loads in a predetermined sequence, a magnetic pickup synchronized with said distributor for producing a signal at predetermined times, a switching transistor connecting said battery to the primary winding of said ignition coil, and circuit means responsive to said signal from said magnetic pickup to actuate said switching means to charge said ignition coil, said switching transistor being actuated to charge said ignition coil by the rising portion of said signal, and actuated to discharge said ignition coil upon the falling portion of said signal, including means for limiting the charging current through said ignition coil, said limiting means comprising a resistor connected to the emitter of said switching transistor for detecting said charging current and feedback means operative in response to said detected charg-