US3373314A

US3373314A - Transistorized ignition system with a saturable transformer control and voltage compensation means

Info

Publication number: US3373314A
Application number: US466949A
Authority: US
Inventors: Ole K Nilssen
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1965-06-25
Filing date: 1965-06-25
Publication date: 1968-03-12
Anticipated expiration: 1985-03-12
Also published as: DE1539199A1

Description

March 12, 1968 0. K. NILSSEN 3,373,314

TRANSISTORIZBD IGNITION SYSTEM WITH A SATURABLE TRANSFORMER CONTROL AND VOLTAGE COMPENSATION MEANS Filed June 25, 1965 r 2 Sheets-Sheet 1 @f I 33 65 6'59 2s 57 56 92 EL 58 {:27 7s IQ44 2 OLE K. NILSSEN INVENTOR MKSIZM March 1 2, 1968 3,373,314

TRANSISTORIZED IGNITION SYSTEM wnn A SATURABLE TRANSFORMER O. K. NILSSEN CONTROL AND VOLTAGE COMPENSATION MEANS 2 Sheets-Sheet 2 Filed June 25, 1965 OLE K. NILSSEN INVENTOR ATTORNEYS United States Patent 3,373,314 TRANSISTGRIZED IGNITIGN SYSTEM. WITH A SATURABLE TRANSFGRMER CUNTRQL AND VOLTAGE CONEFJNSATIGN MEANS Ole K. Nilssen, Livonia, Mich, assignor to The Ford Motor Company, Dearborn, Mich, a corporation of Delaware Filed .lune 25, 1965, Ser. No. 466,949 Claims. ((31. 315-214) ABSTRACT OF THE DISCLGSURE An ignition system for an internal combustion engine in which means are employed for charging an electrical storage means from a source of electrical energy to a substantially constant value irrespective of fluctuations in the terminal voltage of the source of electrical energy. This electrical storage means is charged immediately prior to the requirement for ignition voltages from the electrical storage means. The means for charging the electrical storage means comprises a transistor or other solid state switching device, a saturable switching transformer or core and circuit means coupling the transistor and the saturable switching core or transformer for causing the transistor or other solid state switching device to be switched to the conducting state only during the time that the saturable switching transformer or core is switched from a steady state operating condition to one of its states of saturation. Circuit means are coupled to the source of electrical energy and the saturable switching transformer or core for biasing the saturable switching transformer or core toward one state of saturation as a function of the terminal voltage of the source of electrical energy and this means may comprise a winding coupling the saturable switching transformer or core and connected across the source of electrical energy.

This invention relates to an ignition system for an internal combustion engine, and more particularly to an ignition system for an internal combustion engine in which the output or ignition power is maintained substantially constant notwithstanding wide variations in the terminal voltage of the source of electrical energy that supplies the system.

The present invention is particularly applicable to solid state or transistorized ignition systems, and may be employed with the ignition system shown and described in my copending application S.N. 403,263, filed Oct. 12, 1964. In that system, a transistorized ignition system is shown in which a saturable switching core is used to control a transistor or other solid state switch that is coupled to the source of electrical energy or storage battery and the primary winding of an ignition coil. In that system, the transistor or solid state switch is biased to its con ducting state when the core switches from a steady state operating point into a condition of saturation. As a result, the primary winding of the ignition coil is energized during this period and this period is substantally constant for any given battery voltage and is independent of engine speed.

The present invention provides automatic compensation for changes in the coil energy level that would accompany changes in the terminal voltage of the battery in the above described system. This is done by applying a bias to the saturable switching core that biases at least a portion of the core toward that state of saturation wh ch terminates the conducting time of the transistor. The value of this bias is substantially proportional to the terminal voltage of the source of electrical energy or battery. As a result, the on time of the transistor or the solid state switching device that energizes the primary winding of the 3,373,314 Patented Mar. 12, 1968 "ice ignition coil is substantially inversely proportional to the terminal voltage of the battery. It is axiomatic that the amount of electrical energy that can be stored in the primary winding of an ignition coil in a given time period varies substantially proportionally to the terminal voltage of the source of electrical energy that is coupled directly thereto. The system described provides, therefore, an automatic compensation in which the electrical energy level to which the primary winding of an ignition coil is charged during each ignition cycle is substantially constant regardless of and independent of wide variations in the terminal voltage of its source of electrical energy.

The output power of the ignition system, therefore, that is produced in the secondary winding of the ignition coil remains substantially constant notwithstanding variations in the terminal voltage of the source of electrical energy that may occur during normal operations of the automotive vehicle. These variations may be particularly extreme during the starting of the internal combustion engine. The output power of the ignition system is also independent of engine speed.

Although the invention has been described above in relation to conventional electrical storage devices used in automotive vehicles, for example, an ignition coil having a primary and a secondary winding in which the electrical energy is stored in inductive form in the primary winding of the ignition coil prior to the requirement for ignition voltages, it may also be used with a capacitive discharge system in which the electrical energy is stored in a capacitor just prior to the time that ignition voltages are required by the spark plugs of the engine.

An object of the invention is the provision of an ignition system in which the output power remains substantially constant notwithstanding wide variations in the terminal voltage of the source of electrical energy or storage battery that supplies electrical energy to the system.

A further object of the invention is the provision of an ignition system for an internal combustion engine in which the time that an electrical storage device in the system is energized from a source of electrical energy is substantially inversely proportional to the terminal voltage of the source of electrical energy.

A further object of the invention is the provision of an ignition system for an internal combustion engine in which an electrical storage device in the system is charged to a substantially constant level of electrical energy just prior to the time for the requirement for ignition voltages despite wide fluctuations or variations in the terminal voltage of the source of electrical energy for the system.

A further object of the invention is the provision of an ignition system for an internal combustion engine that will supply a constant amount of electrical energy to the ignition means or spark plugs of the engine irrespective of and independent of engine speed and the terminal voltage of the source of electrical energy supplying energy to the system.

Other objects and attendant advantages of the present invention may be more readily realized when the specifica tion is considered in connection with the attached drawings in which:

FIGURE 1 is a circuit diagram of one embodiment of the invention;

FIGURE 2 is an enlarged partial circuit diagram of the saturable switching core or transformer used in the circuit of FIGURE 1;

FIGURE 3 shows the resultant hysteresis loops of the saturable switching transformer or core shown in FIG- URE 2 as the result of varying amounts of bias applied to the core;

FIGURE 4 is a circuit diagram of another embodiment of the invention, and

FIGURE 5 is a hysteresis loop of the saturable switching core or transformer used with FIGURE 4.

Referring now to the drawings in which like reference numerals designate like parts throughout the several views thereof, there is shown in FIGURE 1 a schematic electrical diagram of one embodiment of the invention in which an ignition coil has a primary winding 11 and a secondary winding 12. The secondary winding 12 is connected through lead 13 to rotating arm 14 of a distributor 16. This rotating arm sequentially connects a plurality of spark plugs 17 to the secondary winding 12 of ignition coil 10 through the lead 13 and the

leads

18,19, 20, 21, 22 and 23.

The primary winding 11 of ignition coil 16 is connected to the negative terminal 26 of a sourre of electrical energy or storage battery 27 through

leads

28 and 31. The other terminal of the primary winding 11 of theignition coil 10 is connected through lead 32 to the dot marked terminal of a winding 33. The other terminal of the winding 33 is connected through lead 34 to an output electrode 35 of a solid state switching device 36. The solid state switching device 36 preferably takes the form of a transistor and theoutput electrode 35 takes the form of the collector of this transistor. The other input electrode 37 of the solid state switching device 36, which in transistor form is the emitter, is connected through leads 41, 42 and 43 to the positive terminal 44 of the source of electrical energy 27.

A saturable switching core of transformer 51 is employed to control the conduction of the solid state switching device or transistor 36. This saturable switching core or transformer has a first winding 52 having its dot marked terminal connected to the positive terminal 44 of the source of electrical energy or battery 27 through lead 53, resistor 54, lead 55, lead 42 and lead 43. The other end or terminal of the winding 52 is connected through lead 56 with contact 57 of ignition contact breaker points 58. The other contact 59 is connected to the lead 31 and hence to the positive terminal 26 of the source of electrical energy 27 through movable arm 61 and lead 62.

The ignition contact breaker points 58 are normally biased to a closed position and are separated or opened periodically by a cam 64 that operates a follower 65 coupled to the arm .61. This cam is operated in synchronism with the rotatable arm 14 of the distributor 16, as shown by the dotted lines 66, and it is arranged so that the ignition contact breaker points 58 open just shortly before the rotating arm 14 makes contact with the leads 18 through 23 respectively of the distributor 16.

The saturable switching core or transformer 51 also has a second winding, previously described, in the form of winding 33 wound thereon so that its dot marked terminal is connected to the primary winding 11 of the ignition coil 10 through the lead 32 and the unmarked terminal is connected through lead 34 with the collector 35 of the solidrstate switching device or transistor 36.

A third winding 75 in the form of a feedback winding has its dot marked terminal connected through a lead 76 to a control electrode or base 77 of the solid state switching device or transistor 36 while the other end of the winding 75 is connected through lead 73, resistor 81 and lead 82 to the lead 42. The lead 42, as previously stated, is coupled to the output electrode 37 ,or emitter of the solid .state switching device or transistor 36 through the lead 41 and is also connected to the positive terminal 44 of the electrical storage battery 27 through the lead 43.

A cross bar 91 of conductive magnetic material is provided with one end positioned intermediate the

windings

33 and 75 and the other end intermediate the

windings

33 and 52. A winding 92 is positioned on the magnetic cross bar 91 and it has one end connected through lead 93, resistor 94, lead 95, lead 42 and lead 43 to the positiveterminal 44 of the source of electrical energy 27. The other end of the winding 92 is connected to the negative terminal 26 of the source of electrical energy 27 4 through

leads

96, 62, 31 and 28. As a result of the connection of the winding 91 to the source of electrical energy 27 by the circuit means described above, a magnetic him is permanently applied to the saturable switching core or transformer 51 during the operation of the ignition system.

The operation of the circuit will now be described, assuming that a small amount of bias is applied by the winding 92 as will be the case when the terminal voltage of the source of electrical energy or battery 27 is low.

The effect of varying terminal voltages that vary the' amount of current through the winding 92 will be explained subsequently.

With the

contacts

57 and 59 of the ignition contact breaker points 58 closed, a circuit will be established through the first winding 52 on the saturable switching core 51 from the source of electrical energy or battery 27. The resistance of this circuit, including the resistance of resistor 54 and the resistance of the winding 52, is such that the number of ampere turns or volt seconds applied to the core 51 is sufiicient to bias it into a negativestate of saturation as designated by the letter A in FIGURE 3. At this time, the solid state switching device or transistor 36 will be in a nonconducting state because no voltage will be developed at this time across the feedback winding 75, and the emitter 35 and the base 77 will be at the same potential. Since the solid state switching device 36 is in the nonconducting state, there will be no current through the primary winding 11 of the ignition coil 10 nor through the winding 33 of the saturable switching core 51.

It should be noted that with the dot convention employed here, current into a dot marked terminal will produce a magnetizing force to drive the core toward a nega-,

tive state of saturation (point A) while current into an unmarked terminal will produce a magnetizing force to drive the core toward a positive state of saturation (point C). Similarly, a flux change from a negative flux state toward a positive flux state will produce a negative voltage at a dot marked terminal of a winding with respect to its unmarked terminal and a flux change from a positive flux state toward a negative flux state will produce a positive voltage at a dot marked terminal of a winding with respect to its unmarked terminal.

When the ignition contact breaker points 58 open under the action of the cam 64 and follower 65, the bias on the saturable switching core will be removed and the flux level will fall to the remnant fiIlX level at B. This changing flux will induce in the feedback winding 75 a negative potential at the dot with respect to the potential at the other end of the winding 75. This will turn the transistor to a conducting state, and provide current flow through the primary winding 11 of the ignition coil 10 and through the winding 33 connected in series with the primary winding 11. Since current flows into the unmarked terminal of winding 33, the core will be switched toward a positive state of saturation and a negative potential will be produced at the dot marked terminal with respect to the unmarked terminal of feedback winding 75, thereby turning the transistor to its fully conducting state by virtue of this feedback action. Current through winding 33provides suflicient magnetizing force on the saturable switching core 51 to drive it from point B into a saturated condition at point C.

When the saturable switching core reaches the saturated state at point C, the feedback voltage in the winding 75 will fall to zero thereby turning off the transistor or solid state switching device 36 and interrupting the current flow through the primary winding 11' of ignition coil 10. This interruption of the current flow will induce a voltage in the primary winding 11 and a stepped up ignition voltage in the secondary winding 12 which will be applied at this time to one of the spark plugs through the lead 13, the rotatable arm 14, and one of the leads 18 through 23 of the distributor 16. This voltage will also act on the winding 33 and tends to reset the core backtow'ard the point A since the voltage across the primary winding 11 has reversed so that a positive potential appears at the dot marked terminal of the winding 33. A positive potential will also be present at the dot marked terminal of feedback winding 75 thereby keeping the solid state switch ing device of transistor 36 in the cutofi condition.

A diode 97 positioned in the lead 34 prevents the saturable switching core 51 from being fully reset by the ignition voltage as it appears across the primary winding A1 of the ignition coil 10 since it prevents current flow into the dot marked terminal of the winding 33 that would have the eliect of resetting the core back to point A in FIGURE 3. Thus, rather than being moved down to the point A in FIGURE 3, which is an unstable position when the ignition contact breaker points 47 are open, the magnetization of the core will now fall only to point D which is a stable position of residual flux. As soon as the

contacts

57 and 59 of the ignition contact breaker points '8 close, the magnetization of the core will be switched back to point A and another ignition cycle will occur only when the

contacts

57 and 59 of the ignition contact breaker points 58 open.

It can be appreciated from an inspection of the circuit diagram of FIGURE 1 that the magnitude of the current through the winding 92 wound on the magnetic cross bar 91 is directly proportional to the terminal voltage of the source of electrical energy 27. It can be appreciated also that the time the primary winding 11 is energized is the time during which the solid state switching device or transistor 36 is in a conducting state. This time is in turn controlled by the period in which a voltage is induced in the feedback winding 75 connected between the base 77 and the emitter 37 of the solid state switching device or transistor 36. This voltage is in turn induced in the feedback winding 75 only during the time in which a change of flux linking the winding 75 and contained in the core 51 is maintained.

An examination of FIGURE 2 will disclose that in the portion of the core linked by the first winding 52. that drives the core toward the saturated state A, that the flux produced by the winding 91 in that portion or" the core aids the flux produced by the winding 52 when that winding is energized by the closing of the ignition contact breaker points 57 and 58. It is apparent also that current through the winding 33 when the solid state switching device or transistor 36 is in a conducting state produces a flux that aids the flux produced by the winding 91 on that portion of the core on which the winding 33 is wound.

The larger the current, therefore, through the winding 91, the larger will be the flux that aids the flux produced by the winding 52 in that portion of the core and also the larger will be the flux which aids the flux in the winding 33 in the portion of the core on which that winding is wound. The net effect of this is to shrink the hysteresis loop, as shown in FIGURE 4, as current through the winding 91 increases, since a flux change that links the feedback winding 7 5 supporting conduction of the transistor or solid state switching device 38 can take place only between the time when the core is switching from one saturated condition of the one leg on which the winding 52 is wound until that portion of the core on which winding 33 is wound is saturated. As a result, the time required to switch the saturable switching core 51 between the two points where a voltage is induced in the winding 75 is reduced as the current through the winding 92 increases and this time is substantially inversely proportional to current through the winding 91.

The time that the transistor 36 is in its conducting state, therefore, is substantially inversely proportional to the magnitude of the current through the winding 91 and hence is inversely proportional to the terminal voltage of the battery 27. It can be appreciated also that the amount of electrical energy stored in the electrical storage device represented by the primary winding 11 of the ignition coil is proportional to both the terminal voltage of the battery 27 and the time that the storage device or primary winding 11 of the ignition coil is energized. As a result, the electrical energy stored in the electrical storage device or primary winding 11 of ignition coil 10 will remain substantially constant independently of wide fluctuations in the terminal voltage of the battery 27, since as the terminal voltage increases the amount of time that the electrical storage device or primary winding 11 is energized prior to the requirement for ignition voltages in the secondary winding 12 varies substantially inversely to the terminal voltage of the source of electrical energy or battery 27.

FIGURE 4 discloses a circuit diagram of another ignition system that also provides substantially constant output energy irrespective of and independently wide fluctuations in the terminal voltage of the source of electrical energy or storage battery 27. It is similar to the circuit shown in FIGURE 1 with certain exceptions. It will be noted that the winding 33 is connected in parallel with the primary winding 11 rather than being connected in series with the primary winding 11 as it is in the circuit shown in FIGURE 1. Also, a zener diode 99 is connected across the winding 52 and the contact breaker points 58 and in series with the resistor 54. Hence, in effect a voltage divider circuit comprising zener diode 99 and resistor 54 is connected across the battery or source of electrical energy 27. It is poled in such a direction as to oppose the how of current in the voltage divider circuit comprising the zener diode 99 and the resistor 54. Its breakdown value, however, is such that the lowest terminal voltage of the battery expected to be encountered is sufficient to break it down. As a result, it provides a constant voltage across its terminals. This zener diode may be selected to provide a six volt drop across it which will remain substantially constant despite wide fluctuations in the terminal voltage of the source of electrical energy or battery 27. As a result, a constant voltage is applied to the winding 52 when the ignition contact breaker points 58 close.

In addition, a biasing winding 101 is positioned about the saturable switching core or transformer 51. This winding has its dot marked terminal connected to the negative terminal 26 of the source of electrical energy 27 through lead 102, limiting resistor 103, lead 104, lead 31 and lead 28. The other end of the winding 101 is connected to the positive terminal 44 of the battery 27 through lead 105, lead 42 and lead 43.

It can be readily appreciated that in the operation of this circuit, the winding 101 is continuously coupled to the source of electrical energy 27 thereby providing a bias on the core 51 that is opposite in direction to the bias provided by the winding 52 when the ignition contact breaker points 58 are closed. In other words, the flux produced by the winding 101 is in the opposite direction to the fiux produced by the winding 52 when the contact breaker points 58 are closed.

FIGURE 5 shows the hysteresis loop for the saturable switching core 51. The winding 52 produces a magnetomotive force having a negative value, as shown, and this in turn produces a flux tending to drive the core toward a negative state of saturation. On the other hand, the winding 101 produces 'a magnetomotive force in a positive direction that tends to drive the core toward the positive state of saturation. The resultant flux in the core, therefore, when the ignition contact breaker points 58 are closed, is the resultant flux produced by the net magnetomotive force resulting from the algebraic sum of the magnetomotive forces produced by the winding 52 and that produced by the winding 101.

It is apparent 'also that the magnetomotive force produced by the winding 101 is directly proportional to the terminal voltage of the battery or source of electrical energy 27. As a result, if the terminal voltage of the source of electrical energy or battery 27 is six volts, the magnetomotive force in ampere turns produced by the winding 101 may be that value designated by the letter D, while if the terminal voltage is twelve volts it may be the value designated by the letter E, and if eighteen volts it may be the value designated by the letter F. The magnetomotive force in ampere turns produced by the winding 52 when the contact breaker points 58 are closed is a constant since the voltage across the winding 52 is a constant determined by the zener diode 99. This value is designated by the letter G. Consequently, the resulting operating point on the hysteresis loop is determined by the algebraic sum of these two values of magnetomotive force as stated above, and if the terminal voltage of the battery is six volts the operating point will be point A on the hysteresis loop, while if twelve points it will be at point B, and if eighteen volts it will be at point C.

The magnetomotive forces produced by currents through the

windings

101 and 52 are selected so that the points A, B and C are located on the substantially straight line portion of the hysteresis loop and so that the distance from the saturated condition of the saturable switching core or transformer 51 at point H to the operating point is inversely proportional to the current through the winding 101 and hence inversely proportional to the terminal voltage of the battery 27. As shown, the distance from the saturated condition at H to the operating point C is one-third of the distance from the point H to the point A, the distance from the saturated condition at H to the operating point B is two-thirds the distance from the saturated condition at H to the operating point A. As pointed out previously, the operating point A is determined by a terminal voltage of the battery 27 of six volts, the operating point B is determined by a terminal voltage of the battery 27 of twelve volts, and the point C is determined by a terminal voltage of the battery 27 of eighteen volts. Thus, as the terminal voltage increases in these incremental amounts of six volts with the top voltage of eighteeen volts, the distance between the saturated condition at H and the operating point decreases proportionally in incremental amounts of one-third. Thus, the time that a voltage is induced in the feedback winding 75 that turns the solid state switching device or transistor 36 to its conducting state is inversely proportional to the terminal voltage of the source of electrical energy or battery 27. As a result, the primary winding 11 will be energized for a period substantially inversely proportional to this terminal voltage.

It can be appreciated, therefore, that the ignition system shown in FIGURE 4 functions in precisely the same manner as the one shown in FIGURE 1 in which the transistor or solid state switching device 36 is switched to its on state when the breaker points 58 are opened, and the period of this conducting state is determined by the time necessary to switch the core from its operating point, for example, either A, B of C, to its saturated state at point H. Thus, the time that the solid state switching device or transistor 36 is in its conducting state and the time the primary winding 11 of the ignition coil 10 is energized is substantially inversely proportional to the terminal voltage of the source of electrical energy or battery 27.

Since the electrical energy stored in the electrical storage device, the primary winding 11 of ignition coil 10, is proportional to the terminal voltage of the source of electrical energy or battery 27 and is inversely proportional to the time that it is energized from this source of electrical energy, the ignition system shown in FIG- URE 4 provides a substantially constant amount of electrical energy to the electrical storage device or primary winding 11 just prior to the requirement for ignition voltages despite wide variations and fluctuations in the terminal voltage in the source of electrical energy 27.

It is readily apparent that this system may be used in a capacitive discharge system as shown in my copending application S.N. 466,948, filed June 25, 1965, and that it is immaterial whether the energy is stored in an inductive core or transformer 51 from entering the cross bar 91 7 since the soft iron becomes in efiect a magnetic open circuit for fast changing magnetic fields that appear in the core or transformer. This construction still permits, however, the fiux in the bar 91 to vary as a function of the changes in the terminal voltage of the battery 27 since these changes are slow compared to the rapidly changing fluxes in the saturable switching core or transformer 51.

In both of the embodiments of the invention shown in FIGURES 1 and 3, the time that the primary winding 11 of ignition coil 10 is energized prior to the requirement for ignition voltages is independent of engine speed. This is brought about by adjusting the parameters of the saturable switching core or transformer 51 and the windings thereon such that the core 51 will always be switched to the saturated condition that brings about a generation of ignition voltages prior to the closing of the contact breaker points 58 that resets the core and commences another ignition cycle.

The present invention thus provides an ignition systern in which the output energy supplied to the ignition devices or spark plugs of an internal combustion engine is substantially constant irrespective of and independently of wide fluctuations in the terminal voltage of the source of electrical energy supplying the ignition system. This is brought about by supplying an energy storage device in the system with a constant amount of electrical energy irrespective of and independently of wide fluctuations in the terminal voltage of the source of electrical energy just prior to the requirement for ignition voltages. As brought out above, the output energy supplied to the ignition devices or spark plugs is also independent of engine speed.

It is to be understood that this invention is not to be limited to the exact construction shown and described, but that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim: 7

1. An ignition system for an internal combustion engine comprising, a source of electrical energy, an ignition coil including a primary winding and a secondary winding, a spark plug means operable in synchronism with the engine for coupling and decoupling said secondary winding from and to said spark plug, and means coupling said primary winding and said source of electrical energy for charging said primary winding from said source of electrical energy to a substantially constant value of electrical energy irrespective of wide fluctuations in the terminal voltage of said source of electrical energy immediately prior to the requirement for ignition voltages in said secondary winding of said ignition coil, said means comprising a transistor, a saturable switching transformer, circuit means coupling said transistor and said saturable switching transformer for causing said transistor to be switched to a conducting state only during the time said saturable switching transformer is switched from a steady state operating condition to one of its states of saturation, and circuit means coupled to said source of energy and said saturable switching transformer for biasing said saturable switching transformer toward said one state of saturation as a function of the terminal voltage of said source of electrical energy.

2. The combination of claim 1 in which said last mentioned means comprises, a winding coupling said saturable switching transformer and connected across said source of electrical energy.

3. An ignition system for an internal combustion engine comprising, a source of electrical energy, an ignition coil including a primary winding and a secondary winding, a spark plug, means operable in synchronism with the engine for coupling and decoupling said secondary winding from and to said spark plug, and means coupling said primary winding and said source of electrical energy for charging said primary winding from said source of electrical energy for a short time period immediately prior to the requirement for ignition voltages in said secondary winding of said ignition coil, said means comprising a transistor, a saturable switching transformer and circuit means coupling said transistor and said saturable switching transformer for causing said transistor to be switched to a conducting state only during the time said saturable switching transformer is switched from a steady state operating condition to one of its states of saturation, and means coupling said source of electrical energy and said saturable switching transformer for biasing said saturable switching transformer toward said one state of saturation substantially proportional to the terminal voltage of said source of electrical energy whereby said primary winding is energized with a substantially constant amount of electrical energy immediately prior to the requirement for ignition voltages irrespective of engine speed and the terminal voltage of said source of electrical energy.

4. An ignition system for an internal combustion engine comprising, a source of electrical energy, an ignition coil including a primary winding and a secondary winding, a plurality of spark plugs, means operable in synchronism with the engine for sequentially coupling said spark plugs to the secondary winding of said ignition coil, a solid state switching device including an output circuit and an input circuit, a saturable switching core capable of being saturated in a first or a second saturable state, a first winding coupled to said source of electrical energy and wound on said saturable core to bias said saturable switching core toward said first saturable state, a second winding coupling said source of electrical energy, said output circuit of said solid state switching device and said primary winding of said ignition coil and wound on said core in a direction to drive said saturable switching core into said second state of saturation, a third winding wound on said saturable core and positioned in the input circuit of said solid state switching device, said third winding wound in a positive feedback direction with respect to said second winding, and means operable in synchronism with said first mentioned means for periodically interrupting the coupling between said first winding and said source of electrical energy whereby said solid state switching device is switched to its conducting state by the energy induced in said third winding and is maintained in its conductive state until said saturable switching core saturates in said second direction whereby said primary winding of said ignition coil is energized only during the period between the interruption of the coupling between said winding and said source of electrical energy and the saturation of said saturable switching core in said second direction, and a fourth winding permanently coupled to said source of electrical energy and wound on said saturable switching core in a direction to bias at least a portion of the saturable switching core toward said first state of saturation.

5. An ignition system for an interna combustion engine comprising, a source of electrical energy, an ignition coil including a primary winding and a secondary winding, a plurality of spark plugs, means operable in synchronism with the internal combustion engine for sequentially coupling said spark plugs to said secondary winding of said ignition coil, a solid state switching device including an output circuit and an input circuit, said output circuit coupled to said source of electrical energy and said primary winding of said ignition coil for energizing said primary winding from said source of electrical energy when said solid state switching device is in a conducting state, a saturable switching core, circuit means coupling said source of electrical energy and said saturable switching core for biasing said saturable switching core toward one state of saturation, and decoupling means operable in synchronism with said first mentioned means for decoupling said source of electrical energy and said saturable switching core, circuit means coupled to said saturable switching core, said output and input circuit of said solid state switching device and said source of electrical energy for causing said saturable switching core to be driven to the other state of saturation and for causing conduction of said solid state switching device only during the period between the decoupling of said source of electrical energy from said saturable switching core and the saturation of said saturable switching core, and means coupling said source of electrical energy and said saturable switching core and biasing said saturable switching core for shortening said period substantially in proportion to the terminal voltage of said battery.

6. An ignition system for an internal combustion engine comprising, a source of electrical energy, an electrical storage means having an input means and an output means, a spark plug, means operable in synchronism with the engine for coupling and decoupling said output means of said electrical storage means from and to said spark plug, and means coupling said input means of said electrical storage means and said source of electrical energy for charging said electrical storage means from said source of electrical energy to a substantially constant value of electrical energy irrespective of wide fluctuations in the terminal voltage of said source of electrical energy immediately prior to the requirements for ignition voltages from said electrical storage means, said means comprising a transistor, a saturable switching transformer, circuit means coupling said transistor and said saturable switching transformer for causing said transistor to be switched to a conductor state only during the time said saturable switching transformer is switched from a steady state operating condition to one of its states of saturation, and circuit means coupled to said source of energy and said saturable switching transformer for biasing said saturable switching transformer toward said one state of saturation as a function of the terminal voltage of said source of electrical energy.

7. The combination of claim 6 in which said last mentioned means comprises, a winding coupling said saturable switching transformer and connected across said source of electrical energy.

8. An ignition system for an internal combustion engine comprising, a source of electrical energy, an electrical storage means having an input means and an output means, a spark plug, means operable in synchronism with the engine for coupling and decoupling said output means of said electrical storage means from and to said spark plug, and means coupling said input means of said electrical storage means and said source of electrical energy for charging said electrical storage means from said source of electrical energy for a short time period immediately prior to the requirement for ignition voltages from electrical storage means, said means comprising a transistor, a saturable switching transformer and circuit means coupling said transistor and said saturable switching transformer for causing said transistor to be switched to a conducting state only during the time said saturable switching transformer is switched from a steady state operating condition to one of its states of saturation, and means coupling said source of electrical energy and said saturable switching transformer for biasing said saturable switching transformer toward said one state of saturation substantially proportional to the terminal voltage of said source of electrical energy whereby said electrical storage means is energized with a substantially constant amount of electrical energy immediately prior to the requirement for ignition voltages irrespective of engine speed and the terminal voltage of said source of electrical energy.

9. An ignition system for an internal combustion engine comprising, a source of electrical energy, an electrical storage means including an input means and an output means, a plurality of spark plugs, means Operable in synchronism with the engine for sequentially coupling said spark plugs to the output means of said electrical storage means, a solid state switching device including an output circuit and an input circuit, a saturable switching core capable of being saturated in a first or a second saturable state, a first winding coupled to said source of electrical energy and wound on said saturable core to bias said saturable switching core toward said first saturable state, a second winding coupling said source of electrical energy, said output circuit of said solid state switching device and said input means of said electrical storage means and wound on said core in a direction to drive said saturable switching core into said second state of saturation, a third winding wound on said saturable core and positioned in the input circuit of said solid state switching device, said third winding wound in a positive feedback direction with respect to said second winding, and means operable in synchronism with said first mentioned means for periodically interrupting the coupling between said first winding and said source of electrical energy whereby said solid state switching device is switched to its conducting state by the energy induced in said third winding and is maintained in its conductive state until said saturable switching core saturates in said second direction whereby said input means of said electrical storage means is energized only during the period between the interruption of the coupling between said winding and said source of electrical energy and the saturation of said saturable switching core in said second direction, and a fourth winding permanently coupled to said source of electrical energy and wound on said saturable switching core in a direction to bias at least a portion of the saturable switching core toward said first state of saturation.

10. An ignition system for an internal combustion engine comprising, a source of electrical energy, an electrical storage means including an input means and an output means, a plurality of spark plugs, means operable in synchronism with the internal combustion engine for sequentially coupling said spark plugs to said output means of said electrical storage means, a solid state switching device including an output circuit and an input circuit, said output circuit coupled to said source of electrical energy and said input means of said electrical storage means for energizing said electrical storage means from said source of electrical energy when said solid state switching device is in a conducting state, a saturable switching core, circuit means coupling said source of electrical energy and said saturable switching core for biasing said saturable switching core toward one state of saturation, and decoupling means operable in synchronism with said first mentioned means for decoupling said source of electrical energy and said saturable switching core, circuit means coupled to said saturable switching core, said output and input circuit of said solid state switching device and said source of electrical energy for causing said saturable switching core to be driven to the other state of saturation and for causing conduction of said solid state switching device only during the period between the decoupling of said source of electrical energy from said saturable switching core and the saturation of said saturable switching core, and means coupling said source of electrical energy and said saturable switching core and biasing said saturable switching core for shortening said period substantially in proportion to the terminal voltage of said battery.

References Cited UNITED STATES PATENTS 3,169,212 2/ 1965 Walters 315223 3,240,198 3/1966 Loudon et a1. 123148 3,306,275 2/ 1967 Hutton 123-148 3,308,801 3/1967 Motto 123148 3,312,211 4/1967 Boyer 123-148 3,312,860 4/1967 Sturm 315223 JAMES W. LAWRENCE, Primary Examiner.

C. R. CAMPBELL, Assistant Examiner.