Ferroresonant capacitor discharge ignition system

Claim 2

In combination with an internal combustion engine, a capacitor discharge ignition system which comprises: an ignition coil having primary and secondary windings and a ferromagnetic core about which said windings are wound; a spark plug having electrodes spaced to form a spark gap, one of said electrodes being coupled to one terminal of said secondary winding; a first capacitor connected in series with said spark gap, one terminal of said capacitor being coupled to the other terminal of said secondary winding; a second capacitor coupled to said primary winding; a DC source of electrical energy; circuit means for charging said second capacitor from said DC source of electrical energy and for discharging said second capacitor through said primary winding in timed relation to operation of said engine; and said second capacitor when discharged through said primary winding producing ferroresonant oscillations in the secondary circuit of said ignition coil.

Claim 3

In combination with an internal combustion engine, a capacitor discharge ignition system which comprises: an ignition coil having primary and secondary windings and a ferromagnetic core about which said primary and secondary windings are wound; a spark plug having electrodes spaced to form a spark gap, one of said electrodes being coupled to one terminal of said secondary winding; a first capacitor connected in series with said spark gap, one terminal of said capacitor being coupled to the other terminal of said secondary winding; a second capacitor coupled to said primary winding; a DC source of electrical energy; circuit means for charging said second capacitor from said DC source of electrical energy and for discharging said second capacitor through said primary winding in timed relation to operation of said engine; and the capacitance of said second capacitor and the magnitude of said DC source of electrical energy being such that when said second capacitor is discharged through said primary winding, the portion of said ferromagnetic core about which said secondary winding is wound alternates between a saturated and unsaturated condition, an alternating current flows through said spark gap and a voltage is produced across said first capacitor which has a frequency f = V m /4N s φ s where V m is the instantaneous maximum voltage across said first capacitor, N s is the number of turns in said secondary winding, and φ s is the magnitude of the magnetic flux within said secondary winding at saturation of said ferromagnetic core.

Claim 4

In combination with an internal combustion engine, a capacitor discharge ignition system which comprises: an ignition coil having primary and secondary windings and a ferromagnetic core about which said primary and secondary windings are wound; a spark plug having electrodes spaced to form a spark gap, one of said electrodes being coupled to one terminal of said secondary winding; a first capacitor connected in series with said spark gap, one terminal of said capacitor being coupled to the other terminal of said secondary winding; a second capacitor coupled to said primary winding; a DC source of electrical energy; circuit means for charging said second capacitor from said DC source of electrical energy and for discharging said second capacitor through said primary winding in timed relation to operation of said engine; and the capacitance of said second capacitor and the magnitude of said DC source of electrical energy being such that when said second capacitor is discharged through said primary winding, the portion of said ferromagnetic core about which said secondary winding is wound alternates between a saturated and unsaturated condition, an alternating current flows through said spark gap and a voltage is produced across said first capacitor which has a frequency f = V m /4N s φ s where V m is the instantaneous maximum voltage across said first capacitor, N s is the number of turns in said secondary winding, and φ s is the magnitude of the magnetic flux within said secondary winding at saturation of said ferromagnetic core.

Claim 5

An ignition system according to claim 2 wherein said first capacitor has a capacitance value in the range from 50 to 1,000 picofarads.

Claim 6

An ignition system according to claim 2 wherein said circuit means includes means for generating a gate signal in timed relation to operation of said engine and circuit means, supplied with said gate signal, for generating an oscillatory signal during said gate signal, said oscillatory signal controlling the frequency at which said second capacitor is discharged through said primary winding.

Claim 7

An ignition system according to claim 4 wherein said oscillatory signal has a period in the range from 0.30 ms to 1.5 ms.

Claim 8

An ignition system according to claim 5 wherein said gate signal has a duration within the range from 1 ms to 5 ms.

Claim 9

An ignition system according to claim 4 wherein said circuit means for charging and discharging said second capacitor further includes interlock circuit means for preventing the discharge of said second capacitor until said second capacitor has been charged from said DC source of electrical energy.

Claim 10

An ignition system according to claim 4 wherein said circuit means for charging and discharging said second capacitor includes a dual monostable multivibrator connected as an oscillator for producing said oscillatory signal, said dual monostable multivibrator being triggered by said gate signal.