US3219877A

US3219877A - Controlled rectifier ignition system

Info

Publication number: US3219877A
Application number: US185290A
Authority: US
Inventors: Richard L Konopa
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1962-04-05
Filing date: 1962-04-05
Publication date: 1965-11-23
Anticipated expiration: 1982-11-23
Also published as: GB960574A

Description

Nov. 23, 1965 R. 1.. KONOPA CONTROLLED RECTIFIER IGNITION SYSTEM 2 Sheets-Sheet 1 Filed April 5, 1962 INVENTOR. Ric/20rd Z. Kano ma a g m H13 AYTORNfY Nov. 23, 1965 R. 1.. KONQPA CONTROLLED RECTIFIER IGNITION SYSTEM 2 Sheets-Sheet 2 Filed April 5, 1962 C/MKG/N CIRCUIT INVENTOR. Richard 1. K02? O/ d BY mam H16 ATTORNEY United States Patent 3,219,877 CONTROLLED RECTIFIER IGNITIUN SYSTEM Richard L. Konopa, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Apr. 5, 1962, Ser. No. 185,290 Claims. (Cl. 315209) This invention relates to ignition systems for internal combustion engines and more particularly to an ignition system wherein a silicon controlled rectifier controls the current flow through the primary winding of an ignition coil.

In conventional ignition systems, it is common practice to use a pair of breaker contacts which are connected in series with a primary winding of the ignition coil and which serve to make the current flowing through the primary winding. In this system, the breaker contacts are subjected to considerable punishment due to arcing of the contacts and due to the repeated opening and closing of the contacts when the engine is running.

In contrast to the above described conventional ignition system, it is an object of this invention to provide an ignition system wherein a controlled rectifier controls the current flow through the primary winding of the ignition coil and wherein a pulse generating means controls the on and off time or the conductivity of the controlled rectifier.

A further object of this invention is to provide an ignition system for an internal combustion engine wherein a controlled rectifier having anode, cathode and gate electrodes is connected such that the anode-cathode circuit of the controlled rectifier controls current flow through the primary winding of an ignition coil and wherein the gate electrode has its voltage varied in synchronism with operation of the engine to control the anode-cathode circuit of the controlled rectifier.

Still another object of this invention is to provide an ignition system for an internal combustion engine wherein a controlled rectifier controls primary winding current and wherein the gate electrode of the controlled rectifier is connected with a magnetic pulse generating device which operates in synchronism with the engine.

A further object of this invention is to provide a controlled rectifier ignition system wherein the gate electrode of the controlled rectifier is connected with a pick-up coil which has voltages generated therein in synchronism with operation of the engine, the voltages generated in the pick-up coil being displaced a predetermined amount and operating to control the turning on and turning ofi of the control rectifier.

Still another object of this invention is to provide an ignition system for an internal combustion engine wherein a controlled rectifier controls current flow through the primary winding of an ignition coil and wherein the gate electrode of the controlled rectifier is connected with a pick-up coil, the pick-up coil having voltages generated therein by a rotating magnetic member which has a pair of permanent magnets that provide time displaced voltages in the pick-up coil as the magnetic member rotates.

A further object of this invention is to provide a controlled rectifier ignition system wherein a capacitor discharges through the controlled rectifier and primary winding of the ignition coil and wherein the conductivity of the controlled rectifier is controlled by a triggering transformer.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

3,219,877 Patented Nov. 23, 1965 In the drawings:

FIGURE 1 is a schematic circuit diagram of an ignition system made in accordance with this invention.

FIGURE 2 is a top view of a magnetic pulse generating means that controls the conductivity of the controlled rectifier shown in FIGURE 1.

FIGURE 3 is a sectional view taken along lines 3-3 of FIGURE 2.

FIGURE 4 shows curves of voltages generated by the magnetic pick-up means illustrated in FIGURE 2.

FIGURE 5 is modified ignition system made in accordance with this invention using a controlled rectifier for controlling the current flow through the primary winding of an ignition coil.

FIGURE 6 is still another modified ignition system using a controlled rectifier to control primary winding current.

Referring now to the drawings and more particularly to FIGURE 1, the reference numeral 10 designates a storage battery or other form of direct current voltage source. One side of the battery 10 is grounded as shown, whereas the opposite side of the battery is connected with lead wire 12 through a manually operable ignition switch 14. The lead wire 12 is connected with the primary winding 16 of an ignition coil which is generally designated by reference numeral 18. The secondary winding of ignition coil 18 is designated by reference numeral 20.

The ignition system of FIGURE 1 utilizes a silicon controlled rectifier generally designated by reference numeral 22 having an anode 24, a cathode 26 and a gate electrode 28. The controlled rectifier 22 is a semiconductor device and is of the type that will permit current to flow be tween the anode 24 and the cathode 26 whenever the gate electrode 28 is more positive than the cathode 26. This controlled rectifier 22 is also of the type that maintains conduction between the anode 24 and the cathode 26 once a pulse of voltage has been applied to the gate electrode 28 that drives the gate positive with respect to the cathode 26. On the other hand, the controlled rectifier 22 will be driven nonconductive between the anode 24 and the cathode 26 when the cathode 26 becomes more positive than the gate electrode 28.

The device for varying the voltage of the gate electrode 28 with respect to the cathode 26 is a pick-up coil 30 which is connected between the gate electrode 28 and ground. It is seen that the cathode electrode 26 is grounded through lead wire 32 and that the anode 24 of the controlled rectifier 22 is connected with one side of the primary winding 16 via the lead wire 34.

The pick-up coil 30 forms a part of a magnetic pulse generating device which is illustrated in FIGURES 2 and 3. From FIGURE 3, it can be seen that the pick-up coil 30 is located between

pole pieces

36 and 38 which are joined by an annular member 40. The

pole pieces

36 and 38 and the annular member 40 are all formed of magnetic material. The pole piece 36 is formed with radially extending teeth or projections 36a. Pole piece 38 is also formed with radially extending projections 38a which are identical with projections 36a and which are in alignment with the projections 36a.

The coil winding 30 is annular in configuration as is clearly apparent from FIGURE 3. The coil winding assembly which includes the

pole pieces

36 and 38 and the annular member 40 are supported by a housing or base 42 which supports a rotatable shaft 44. The housing or base 42 is formed of a non-magnetic material such as die cast aluminum. The

parts

36, 38 and 40 may be secured together in any suitable fashion and could be carried by a breaker plate that would be adjustable relative to the

magnets

46 and 48 and shaft 44.

The shaft 44 carries a non-magnetic insert 45 which,

in turn, supports a pair of permanent magnets 46 and 43 which have opposite magnetic polarities as is illustrated in FIGURE 3. Thus the top end of permanent magnet 46 is a north pole, whereas the top end of permanent magnet 48 is a south pole. The tips of the

permanent magnets

46 and 48 swing past the projecting

portion

36a and 38a of the

pole pieces

36 and 38 as the shaft 44 rotates. The permanent magnets may be of the ceramic ferrite type and are secured to the insert 45 in any wellknown manner, for example, by bonding. It can be seen from FIGURE 2 that the

permanent magnets

46 and 48 are not located directly opposite each other, so that when the permanent magnet 46 is in exact alignment with one pair of radial projections 36a and 33a, the permanent magnet 48 is out of alignment with all of the other radial projections. If the permanent magnet assembly in FIGURE 2 is rotating clockwise, it is seen that the permanent magnet 46 will swing past a pair of projections before the permanent magnet 48 swings past another pair.

The voltage wave form developed in the pick-up coil 30 as the shaft 44 rotates is depicted in FIGURE 4. As permament magnet 48 swings past one of the pairs of radially extending teeth of the pole pieces, a voltage is generated which is depicted between points A and B on the curve of FIGURE 4. As the permanent magnet 48 swings past a pair of radial projections, the flux flowing in the magnet circuit approaches a maximum and then goes to a minimum. This will cause a voltage to be generated between points A and B on FIGURE 4 which reverses its polarity. The first portion of the part of the curve extending between points A and B is caused by the changing of flux in the magnetic circuit as the magnet approaches a .pair of projecting teeth and then becomes exactly aligned with the teeth. As the magnet leaves the teeth, the other portion of the curve is developed which is in a reverse direction. It thus is seen that as the magnet 48 sweeps by a pair of projecting teeth, a voltage is developed which reverses its polarity.

The :portion of the curve extending between points C and D on FIGURE 4 is due to the permanent magnet 46 sweeping by a pair of projecting teeth of the pole pieces. It is seen that this voltage is exactly the reverse of the voltage developed due to magnetic action of permanent magnet 48, since the magnetic polarities of the two permanent magnets are opposite. The portion of the curve between points B and C corresponds to a time period when either

permanent magnet

46 or 48 are passing by the projecting teeth of the pole pieces. The portion of the curve between points E and F corresponds to the condition where the permanent magnet 48 sweeps by a pair of teeth of the pole pieces and this voltage wave form is the same as the portion of the FIGURE 4 curve extending between points A and B but is displaced in time. It will be appreciated that as the shaft 44 rotates, a continuous wave form of the type illustrated in FIGURE 4 is generated in the pick-up coil 30.

The shaft 44 as is seen from the dotted lines of FIG- URE 1, is driven in synchronism with the engine 50 which is powered by the ignition system of this invention. The engine 50 has spark plugs 52 which are connected respectively with the lead wires 54. The lead wires 54 are connected with the electrodes 56 of a conventional distributor 57 which has a rotor contact 53 electrically connected with the secondary winding 20 of the ignition coil via the lead wire 60. The high voltages induced in the secondary winding 20 are thus supp-lied to the spark plugs 52 via the rotor contact 58 and the fixed distributor contacts or electrodes 56. The rotor contact 58 is driven in synchronism with the engine and in synchronism with the shaft 44 as is depicted by the dotted lines shown in FIGURE 1.

When it is, desired to energize the ignition system illustrated in FIGURES 1 through 4, the ignition switch 14 is closed. The engine 50 is then cranked and pulses of voltage are induced in the coil winding 36 as depicted in FIGURE 4. These pulses of voltage are also induced in the coil winding 30 when the engine is running as is obvious to those skilled in the art.

When the voltage wave form of FIGURE 4 reaches point G on the curve, the gate electrode 28 of the silicon controlled rectifier 22 is positive with respect to the cathode 26 so that a current now flows from battery 10, through the primary winding 16 and through the anode cathode circuit of the controlled rectifier 22. The controlled rectifier is therefore turned on between its anode and cathode and current flows in the primary circuit of the ignition system. As the voltage wave form of FIG- URE 4 goes to point B and between points B and C, the controlled rectifier still is turned on since it is of the type that once turned on will remain on until a pulse is applied across the gate and cathode electrodes which drives the gate electrode negative with respect to the cathode. In view of this, the controlled rectifier 22 remains turned on until the voltage wave form reaches point H on the curve of FIGURE 4 where it can be seen that the gate electrode 28 is now driven negative with respect to the cathode 26. When this happens, the current is interrupted or greatly reduced that is passing through the primary winding 16 and a large voltage is induced in the secondary winding 20 which is applied to a spark plug through the rotor contact 58, one of the distributor contacts 56 and one of the lead wires 54. The controlled rectifier will remain turned off between H and J on the curve of FIG- URE 4 and when point I is reached, the controlled rectifier will be turned back on to once more cause the controlled rectifier to conduct between its anode and cathode.

It can be seen from the foregoing that the magn tic pulse generating means supplies voltage pulses of positive and negative polarity which cause the controlled rectifier to be turned on and off in synchronism with operation of the engine 50. It also can be seen from FIGURE 4 that the time that the controlled rectifier 22 is turned on is greater than the time that the controlled rectifier is turned off during a given angular rotation of shaft 44. This is advantageous in an ignition system as it is desirable to have the on time greater than the off time, so that a sufficient flux is built up in the magnetic circuit of the ignition coil to cause a high voltage to be developed in the secondary winding 20 when the controlled rectifier turns off.

Referring now more particularly to FIGURE 5, a modified ignition system made in accordance with this invention is illustrated. In FIGURE 5, the battery is designated by reference numeral 60 and the manually operable ignition switch is designated by reference numeral 62. An ignition coil 64 is provided having a primary winding 66 and a secondary winding 68. One side of the secondary winding 68 is grounded and the opposite side is connected with a rotor contact 70 which swings past distributor electrodes '72 connected with the spark plugs 74 of an engine 76. The engine 76 drives the rotor contact 70 in a manner well known to those skilled in the art.

The primary winding 66 of the ignition coil 64 is con nected between the ignition switch 62 and the anode 78 of a controlled rectifier 80. The controlled rectifier 80 has a cathode 82 which is grounded and has a gate electrode 84 which is connected with the lead wire 86. The anode-cathode circuit of the controlled rectifier 80 controls current flow through the primary winding 66.

The conductivity of the controlled rectifier 80 and its anode-cathode circuit is controlled by

breaker contacts

88 and 90 and a triggering transformer 92. The breaker contact 88 is carried by a breaker lever 94 which has the usual rubbing block 96. The rubbing block is engaged by a breaker cam 98 which is driven in synchronism with the engine 76 and the rotor contact 70. The breaker contact 88 is electrically connected with the junction 100 via the lead wire 102. The fixed breaker contact 90 is connected with the primary winding 104 of the triggering transformer 92. The secondary winding 106 of the triggering transformer is connected with lead wire 86 and thus is connected with the gate electrode 84 of the controlled rectifier 80. The primary and

secondary windings

104 and 106 are connected together at junction 108 and this junction is grounded.

When the ignition switch 62 is closed and when the

breaker contacts

88 and 90 are opening and closing due to operation of the engine 76 or due to cranking of the engine, the controlled rectifier 80 is turned on and off to control the current flow through the primary winding 66. When

breaker contacts

88 and 90 close, current fiows through the primary winding 104 of the triggering transformer 92, from the battery 60, through switch 62, junction 100, lead wire 102, the closed breaker contacts 88 and 00 and then through the primary winding 104 to ground. When current is increasing through the primary winding 104, a voltage is induced in the secondary winding 106 having the polarity shown in FIGURE 5. With this polarity, the gate electrode 84 is driven positive with respect to the cathode 82 of the controlled rectifier and as a result, the controlled rectifier conducts between its anode and cathode. This completes an energization circuit for the primary winding 66 and current then flows from the battery 60, through ignition switch 62, through primary winding 66, and through the anode-cathode circuit of controlled rectifier 80. From the foregoing, it can be seen that when the

breaker contacts

88 and 90 close, current will flow through the primary winding 66 of the ignition coil 64.

When the breaker cam 98 causes the

contacts

88 and 90 to separate, a voltage is induced in the secondary winding 106 which is opposite to that illustrated in FIGURE 5. This voltage will drive the cathode of controlled rectifier 80 more positive than the gate electrode and therefore will turn the controlled rectifier off or substantially reduce its conduction in its anode-cathode circuit. This interrupts the current flow through the primary winding 66 and a large voltage is therefore induced in the secondary winding which is transmitted to one of the spark plugs via rotor contact 70, one of the distributor cap electrodes '72 and one of the lead wires connected with a spark plug 74.

Referring now more particularly to FIGURE 6, a modified ignition system is illustrated which in some respects is similar to the system illustrated in FIGURE 5. In FIG- URE 6, the reference numeral 110 designates a source of direct current power such as a battery which has one side thereof grounded and which has an opposite side connected with the ignition switch 112. The ignition switch is connected with a charging circuit 114 which could take several Well-known forms. The charging circuit 114 could be, for example, a DC. to DC. converter, a multivibrator, or a vibrator-transformer which is operable to transform the relatively low voltage of the battery 110 to a relatively high voltage at

output terminals

116 and 118. The output terminal 118 is grounded whereas the other DC. output terminal 116 is connected with lead wire 120.

The lead wire 120 is connected with a junction 122 and a capacitor 124 is connected between junction 122 and ground. The lead wire 120 is connected with the primary winding 126 of an ignition coil 128 which has a secondary winding 130. The secondary winding 130 has one side thereof connected to ground and has an opposite side connected with a spark discharge device 132.

The system of FIGURE 6 like the system of FIGURE 5, has a triggering transformer 134 which includes a primary winding 136 and a secondary winding 138. The primary winding is connected in series with breaker contacts 140 which may be operated by an apparatus similar to that which operates the

breaker contacts

88 and 90 in FIGURE 5. In other words, the breaker contacts 140 open and close in synchronism with operation of the engine. In this connection, it is be pointed out that the ignition system may include a plurality of spark plugs 6 132 which are connected with secondary winding by a suitable rotor and distributor contacts.

The primary winding 136 is connected with the charging circuit 114 and may be supplied with current from the input terminals of the charging circuit and thus from the battery 110. The secondary winding 138 has one side connected to ground and has an opposite side connected with the lead Wire 140.

The lead wire 141 is connected with the gate electrode 142 of a silicon controlled rectifier 144. The controlled rectifier has an anode 146 and a cathode 148. It is seen that the anode 146 is connected to one side of primary winding 126, whereas the cathode 148 is grounded. A diode 150 is connected across the cathode and anode of the controlled rectifier 144.

When the ignition switch 112 is closed, the charging circuit 114 is energized and a high DC. voltage appears between

junctions

116 and 118. This voltage will charge the capacitor 124 and the controlled rectifier 144 will be turned off providing that the breaker contacts are closed.

When ignition is desired, the breaker contacts 140 are opened. This interrupts the current through the primary winding 136 of the triggering transformer 134 and will cause a voltage to be induced in the secondary winding 138 which is of such a polarity as to drive the gate electrode 142 positive with respect to the cathode 148. This will cause the controlled rectifier 144 to turn onbetween its anode and cathode and the capacitor 124 will discharge through the primary winding of the ignition coil creating a high voltage at the secondary winding 130 to cause a firing of the spark plug 132. The inductance of the primary winding 126 of the ignition coil 128 will cause the capacitor 124 to now charge with a reversed polarity. When the inductive charge has passed, the charge on the capacitor will pass through the diode and at the same time will apply a reverse bias across the anode and cathode electrodes of the controlled rectifier 144 to turn the controlled rectifier 144 off in preparation for the next cycle. The breaker contacts 140 will then close, the capacitor will charge and the cycle will repeat.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. An ignition system for an internal combustion engine comprising, a source of direct current voltage, an ignition coil having a primary winding and a secondary winding, spark distributing means connected between said secondary winding and spark plugs on said engine for supplying spark energy to the spark plugs of said engine, a controlled rectifier having anode, cathode and gate electrodes, said controlled rectifier being of a type which can be turned on in its anode-cathode circuit when its gate has a higher potential than its cathode and being of a type which is turned off in its anode-cathode circuit when the potential of its cathode is higher than the potential of its gate, means connecting the anode and cathode electrodes of said controlled rectifier and said primary winding of said ignition coil in series across said source of direct current and pulse generating means including a coil winding connected across the gate and cathode electrodes of said controlled rectifier and a rotor carrying circumferentially spaced permanent magnets which have opposite magnetic polarities relative to said coil winding driven by said engine for inducing in said coil winding a series of spaced, discrete pairs of successive alternating current pulses, the pulses of each pair being of opposite phase relationship and the period of each pulse pair being of a time duration less than the period between successive pulse pairs.

2. An ignition system for an internal combustion engine comprising, an ignition coil having a primary winding and a secondary winding, a source of direct current voltage, a controlled rectifier having anode, cathode and gate electrodes, said controlled rectifier being of a type which can be turned on in its anode-cathode circuit when its gate has a higher potential than its cathode and being of a type which is turned off in its anode-cathode circuit when the potential of its cathode is higher than the potential of its gate, means connecting the anode-cathode circuit of said controlled rectifier and said primary winding in series across said source of direct current, and voltage pulse generating means including a coil winding connected across the gate and cathode electrodes of said controlled rectifier and a magnetic means driven by said engine for inducing in said coil a series of spaced, discrete pairs of successive alternating current pulses, the pulses of each pair being of opposite phase relationship and the period of each pulse pair being of a time duration less than the period between successive pulse pairs.

3. An ignition system for an internal combustion engine comprising, a source of direct current, an ignition coil having a primary winding and a secondary winding, a controlled rectifier having anode, cathode and gate electrodes, said controlled rectifier being of a type which can be turned on in its anode-cathode circuit when its gate has a higher potential than its cathode and being of a type which is turned off in its anode-cathode circuit when the potential of its cathode is higher than the potential of its gate, means connecting the anode-cathode circuit of said controlled rectifier and the primary winding of said ignition coil in series across said source of direct current, and pulse generating means including a pick-up coil connected with the gate and cathode electrodes of said controlled rectifier and a rotor member carrying two oppositely poled, asymmetrically, circumferentially spaced permanent magnets rotated by said engine in cooperative relationship with said pick-up coil for inducing in said pickup coil a series of spaced, discrete pairs of successive alternating current pulses, the pulses of each pair being of opposite phase relationship and the period of each pulse pair being of a time duration less than the period between successive pulse pairs.

4. An ignition system for an internal combustion engine comprising, an ignition coil having a primary winding and a secondary winding, a source of direct current, a controlled rectifier having anode, cathode and gate electrodes, said controlled rectifier being of a type which is biased to a conductive condition in its anode-cathode circuit when its gate has a higher potential than its cathode and being of a type which is biased to a nonconductive condition in its anode-cathode circuit when the potential of the cathode is higher than the potential of its gate, means connecting the anode-cathode circuit of said controlled rectifier and said primary winding in series across said source of direct current, and pulse generating means including an annular pick-up coil connected with the gate and cathode electrodes of said controlled rectifier and a rotor member .carrying at least two oppositely poled, asymmetrically,

circumferentially spaced permanent magnets rotated by said engine within the space defined by said annular pickup coil for inducing in said pick-up coil a series of spaced, discrete pairs of successive alternating current pulses, the pulses of each pair being of opposite phase relationship and the period of each pulse pair being of a time duration less than the period between successive pulse pairs.

5. An ignition system for an internal combustion engine comprising, a source of direct current, an ignition coil having a primary winding and a secondary winding, a controlled rectifier having anode, cathode and gate electrodes, said controlled rectifier being of a type which is capable of being turned on by a signal which at least temporarily drives the gate to a higher potential than the cathode and being of a type which is capable of being turned off by a signal which causes the cathode to have a higher potential than the gate, means connecting the anode-cathode circuit of said controlled rectifier and said primary winding in series across said source of direct current, and pulse generating means including an annular pick-up coil connected between the gate and cathode electrodes of said control rectifier located between a pair of annular pole pieces each having a plurality of axially aligned projections and a rotor member carrying two oppositely poled, asymmetrically, circumferentially spaced permanent magnets rotated by said engine within the space defined by said annular pick-up coil for inducing in said pick-up coil a series of spaced, discrete pairs of successive alternating current pulses, the pulses of each pair being of opposite phase relationship and the period of each pulse pair being of a time duration less than the period between successive pulse pairs.

References Cited by the Examiner UNITED STATES PATENTS 2,787,649 4/1957 Ballard et a1 123-148 2,852,588 9/1958 Hartman 123l48 2,878,298 3/1959 Giacoletto 123148 2,943,013 6/1960 Cook 315-209 X 2,985,796 5/1961 Gaylor 315-21 8 X 3,032,685 5/1962 Loomis 315-209 3,078,391 2/1963 Bunodiere et al. 3-15209 3,140,423 7/1964 Roberts et a1. 315-201 FOREIGN PATENTS 494,607 10/193 8' Great Britain.

OTHER REFERENCES Applications and Circuit Design Notes, published by Solid State Products Inc., December 1959, pages 2 and 4.

JOHN W. HUCKERT, Primary Examiner. JAMES D. KALLAM, DAVID J. GALVIN, Examiners.

Claims

1. AN IGNITION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING, A SOURCE OF DIRECT CURRENT VOLTAGE, AN IGNITION COIL HAVING A PRIMARY WINDING AND A SECONDARY WINDING, STARK DISTRIBUTING MEANS CONNECTED BETWEEN SAID SECONDARY WINDING AND SPARK PLUGS ON SAID ENGINE FOR SUPPLYING SPARK ENERGY TO THE SPARK PLUGS OF SAID ENGINE, A CONTROLLED RECTIFIER HAVING ANODE, CATHODE AND GATE ELECTRODES, SAID CONTROLLED RECTIFIER BEING OF A TYPE WHICH CAN BE TURNED ON IN ITS ANODE-CATHODE CIRCUIT WHEN ITS GATE HAS A HIGHER POTENTIAL THAN IS CATHODE AND BEING OF A TYPE WHICH IS TURNED OFF IN ITS ANODE-CATHODE CIRCUIT WHEN THE PONTENTIAL OF ITS CATHODE IS HIGHER THAN THE POTENTIAL OF ITS GATE, MEANS CONNECTING THE ANODE AND CATHODE ELECTRODE OF SAID CONTROLLED RECTIFIER AND SAID PRIMARY WINDING OF SAID IGNITION COIL IN SERIES ACROSS SAID SOURCE OF DIRECT CURRENT AND PULSE GENERATING MEANS INCLUDING A COIL WINDING CONNECTED ACROSS THE GATE AND CATHODE ELECTRODES OF SAID CONTROLLED RECTIFIER AND A ROTOR CARRYING CIRCUMFERENTIALLY SPACED PERMANENT MAGNETS WHICH HAVE OPPOSITE MAGNETIC POLARITIES RELATIVE TO SAID COIL WINDING DRIVEN BY SAID ENGINE FOR INDUCING IN SAID COIL WINDING A SERIES OF SPACED, DISCRETE PAIRS OF SUCCESSIVE ALTERNATING CURRENT PULSES, THE PULSES OF EACH PAIR BEING OF OPPOSITE PHASE RELATIONSHIP AND THE PERIOD OF EACH PULSE PAIR BEING OF A TIME DURATION LESS THAN THE PERIOD BETWEEN SUCCESSIVE PULSE PAIRS.