US3445723A - Ignition system applying induced voltage to the coil primary - Google Patents

Description

May 20, 1969 Q o. KJNILSSEN IGNITION SYSTEM APPLYING INDUCED VOLTAGE TO THE COIL PRIMARY Filed Dec. 1. 1966 MAX 8 MAX 01. E' K N/LSSEN INVENTOR. 8Q

ATTORNEYQW United States Patent US. Cl. 315-209 3 Claims ABSTRACT OF THE DISCLOSURE This disclosure describes an ignition system permitting current to build up in an inductor and then applying the voltage induced in the inductor when the current is stopped to the primary winding of an ignition coil. The ignition pulse resulting in the coil secondary winding is transmitted to an appropriate spark plug. The inductor can be in parallel with the coil primary winding with a rectifier in one of the connecting leads blocking battery voltage and current from the coil primary while passing induced voltage and current to the coil primary. A control circuit comprising a saturable switching core and a transistor permits the current buildup in the inductor for a time period independent of engine speed.

BRIEF SUMMARY OF THE INVENTION Most present day ignition systems for internal combustion use breaker points to control directly the electrical current through the ignition coil primary winding. The sudden change in current occurring when the breaker points open induces voltage in the coil secondary winding that is distributed to the appropriate spark plug. In some of the proposed electronic systems, a capacitor is charged by any of a variety of means and then discharged through the coil primary winding to produce the ignition voltage.

Ignition systems using breaker points directly must provide a long current buildup time to avoid inducing a spark during current buildup. Such systems waste thereby a considerable amount of electrical energy. Capactive discharging systems tend to resonate while discharging, which produces multiple ignition sparks per discharge cycle. Multiple sparks of course reduce spark plug life and can cause undesirable engine combustion characteristics.

The ignition system of this invention permits very rapid charging times because no current passes through the coil primary winding during the charging cycle. This feature alone provides significant savings in electrical energy. When combined with a control circuit permitting current buildup for a predetermined time period that is independent of engine speed, system economy becomes extremely high. In addition, the ignition voltage and current wave forms are substantially equivalent to those produced by ignition systems using breaker points to control directly the current through the coil primary winding which is the type of wave form present day internal combustion engines have been designed to use.

In an ignition system of this invention having a source of electrical energy and an ignition coil with primary and secondary windings, an ignition voltage is produced in the coil secondary winding by connecting an inductor with the electrical energy source and connecting in series with the inductor a control means switchable from conduction to nonconduction in timed relationship to rotating components of the engine. Circuitry couples the inductor means with the coil primary winding to apply to the coil primary winding the voltage induced in the inductor when the control means switches.

The inductor can be connected in parallel with the coil primary winding, and a rectifier can be located in one of the leads connecting the inductor with the coil primary in a manner blocking battery current from the coil primary but passing induced cur-rent from the inductor. A transistor having its emitter and collector terminals in series with the inductor can be used in the control means. A saturable switching core then can be associated with the transistor and with a set of breaker points to turn on the transistor for a predetermined time period that is independent of engine speed. The time period is selected so the inductor attains an energy level adequate for proper ignition at the lowest anticipated battery voltage.

DESCRIPTION OF THE DRAWING VIEWS FIGURE 1 is a schematic diagram of an ignition system of this invention having the inductor in parallel with the coil primary winding and having a set of breaker points, a saturable switching core, and a transistor in the control means. FIGURE 2 shows the hysteresis loop of the saturable switching core, and FIGURE 3 is a sche matic diagram of the ignition system in which the inductor comprises a transformer having its secondary winding connected through a rectifier to the ignition coil primary winding.

DETAILED DESCRIPTION Construction Referring to FIGURE 1, a battery 10 has its positive terminal 12 connected through an ignition switch 14 to a positive buss lead 16. The negative terminal 18 of battery 10 is connected to a negative buss lead 20 and to ground at 22. Y

An ignition coil 24 having a primary Winding 26 and a secondary winding 28 has one terminal of secondary winding 28 connected to ground at 30. The other terminal or secondary winding 28 is connected to a rotating arm 32 of a distributor assembly 34. Arm 32 sequentially connects secondary winding 28 with one of a plurality of spark plugs 35.

One terminal of coil primary winding 26 connects with buss lead 16 and the other terminal connects with the cathode 360 of a diode 36. An inductor 38 has one terminal connected to buss lead 16 and the other terminal connected to a lead 40 that connects with the anode 36a of diode 36. Thus, inductor 38 is in parallel with coil primary 26, and diode 36 serves as a rectifier in one of the leads connecting inductor 3-8 with coil primary 26.

A cam and breaker point assembly 42, a saturable switching core 44, and a transistor 46 are the principal components of a circuit controlling the current through inductor 38. Cam 48 of assembly 42 is driven by rotating components (not shown) of the engine. Dotted line 50 represents the conventional mechanical connection between cam 48 and arm 32 of distributor assembly 34 so arm 32 also rotates with engine components. A set of breaker points 52 and 54 are associated with cam 48 and are moved into and out of touch thereby.

Switching core 44 has a primary Winding 56, a secondary winding 58, and a tertiary winding 60. Primary winding 56 has its undotted terminal connected through a resistor 61 to buss lead 16 and its dotted terminal connected to breaker point 54. Breaker point 52 is connected to buss lead 20. Tertiary winding 60 has its dotted terminal connected to lead 40 and its undotted terminal connected to a lead 62 that in turn connects with emitter 462 of transistor 46. Collector 460 of transistor 46 connects with buss lead 20.

Secondary winding 58 has its dotted terminal connected with lead 62 and its undotted terminal connected to base 46b of transistor 46. A capacitor 63 is connected between lead 62 and lead 20.

Connections in FIGURE 3 are similar to those in FIG- URE 1 except the terminal of coil primary 26 connected in FIGURE 1 to buss lead 16 is connected to the dotted terminal of the secondary winding 64 of a transformer 66. Lead 40 is removed and the undotted terminal of secondary Winding 64 is connected to anode 36a. The primary Winding 38' of transformer 66 serves as the inductor and has its dotted terminal connected to lead 16. The undotted terminal of primary winding 38' is connected to the dotted terminal of winding 60.

Operation Windings 56, 58 and 60 are arranged on core 44 so conventional current into an undotted terminal of a winding produces a negative magnetizing force tending to switch core 44 toward a negative flux density level. Conversely, conventional current into a dotted terminal of one of the windings produces a positive magnetizing force tending to switch core 44 toward a positive level of flux density. When the flux density in core 44 is becoming more negative, a negative voltage appears at the dotted terminals of the windings and of course when the flux density is becoming more positive, a positive voltage appears at the dotted terminals.

With breaker points 52 and 54 in touch with each other, the current in winding 56 switches core 44 into its negative saturation state (the point B Max. shown in FIG- URE 2). During switching of core 44 toward the -B Max. point, the voltage appearing at the undotted terminal of secondary Winding 58 keeps transistor 46 turned off.

When cam 48 moves breaker point 52 out of touch with breaker point 54, the magnetizing force H disappears from core 44 and the flux density in core 44 moves from -B Max. to the point B. This change induces a voltage in winding 58 that turns on transistor 46. A current then begins building up in inductor 38 and winding 60. Since the current is entering winding 60 at the dotted terminal, a positive magnetizing force is applied by winding 60 that switches core 44 toward the point marked +B Max. in FIGURE 2. The switching induces additional current in winding 58 to increase conduction of transistor 46.

The induced voltage at the dotted terminal of winding 58 disappears when core 44 reaches positive saturation at the point +B Max. and transistor 46 turns off. Current in inductor 38 stops suddenly and the self-inductance of inductor 38 induces a current with a voltage that is positive at the lead 40 side of winding 38. The induced current passes through diode 36 and is applied to coil primary winding 26. Coil 24 transforms the current and voltage into a higher voltage that is applied to an appropriate spark plug 35. Diode 36 prevents current in coil primary winding 26 while transistor 46 is conducting.

When the current in winding 60 stops, core 44 moves from +B Max. to the point B+. Transistor 46 remains off during this switch because a negative voltage is induced in winding 58. Subsequently, cam 48 moves breaker point 52 into touch with breaker point 54 and current begins again in primary winding 56. The magnetizing force produced thereby switches core 44 from the point B+ to the point B Max. and the above ignition cycle is repeated. Note that a current exists in inductor 38 only while transistor 46 is conducting and transistor 46 conducts only during the time period needed to switch core 44 from the point B Max. to the point +B Max.

In FIGURE 3, windings 38' and 64 are arranged on transformer 66 so a voltage across winding 38 positive at the dotted terminal thereof transforms into a voltage across winding 64 positive at the dotted terminal of winding 64. Anode 36a then is negative with respect to cathode 36c. Thus, when transistor 46 is conducting and a current is building up in winding 38', diode 36 blocks the induced voltage in winding 64 from coil primary winding 26. However, when transistor 46 turns olf, the voltage across winding 38 becomes positive at the undotted terminal. Diode 36 then is forward biased and it applies the voltage and current appearing across winding 64 to coil primary winding 26. Coil 24 transforms the voltage and current into an ignition spark.

Thus, this invention provides an ignition system using the voltage induced in an inductor to produce a voltage in the coil primary winding that in turn produces an ignition spark. Only the induced voltage from the inductor is applied to the coil primary winding; a rectifier blocks battery voltage from the coil primary while current builds up in the inductor. A switching core coupled to a transistor permits the current to build up in the inductor for a time period that is independent of engine speed. Very little electrical energy is wasted, therefore, and the ignition system of this invention has an extremely high electrical efficiency.

What I claim is: 1. In an ignition system for any internal combustion engine having a source of electrical energy and an ignition coil with primary and secondary windings, means for producing an ignition voltage in the coil secondary winding comprising an inductor means, control means in series with said inductor means, said control means being switchable from conduction to nonconduction in timed relationship to rotating components of the engine, said control means comprising a transistor having its emitter and collector terminals in series with the inductor means, a set of breaker points actuated by the engine, and a saturable switching core having primary, secondary and tertiary windings thereon, said primary winding being in series with said breaker points, said secondary winding connecting with the base terminal of the transistor and said tertiary winding being in series with the emitter and collector terminals of the transistor, said windings being arranged to turn on the transistor when the breaker points are actuated and turn off the transistor when the switching core saturates, and

circuit means coupling the inductor means directly with the coil primary winding, said circuit means applying to the coil primary winding the voltage induced in the inductor means when the control means switches, said circuit means comprising a rectifier means in one of the leads connecting the inductor means with the coil primary winding for blocking significant amounts of battery current from the coil primary winding while passing induced current to the primary winding.

2. The ignition system of claim 1 in which the inductor means is in parallel with the coil primary winding.

3. The ignition system of claim 1 in which the inductor means comprises a transformer having its primary winding in series with the control means and the circuit means couples the transformer secondary winding to the coil primary winding.

References Cited UNITED STATES PATENTS 3,395,686 8/1968 Minks 3l5l09 3,252,049 5/1966 Raybin. 3,312,211 4/1967 Boyer.

JOHN W. HUCKERT, Primary Examiner.

J. D. CRAIG, Assistant Examiner.

US. Cl. X.R. 123148; 315215

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