US 4,375,794 AGranted

External inductive solid state ignition system

AssigneeTecumseh Products Company

InventorAnthony E. Wasmer

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Abstract

An ignition system of the contactless interrupt type for an internal combustion engine is disclosed with a control circuit including a pair of solid state semiconductor devices with one connected to the other in a controlling relation. The ignition system has a high voltage transformer with a secondary winding coupled to a spark plug and a primary winding shunted by the controlled one of the pair of semiconductors. A current flow is induced in the primary winding and then interrupted near its maximum value by rendering both of the semiconductor devices nonconducting. The controlling semiconductor may be a gate controlled switch or so-called gate turn-off device while the controlled semiconductor may be a power transistor. The primary winding current flow is induced by movement of a flywheel supported permanent magnet past the high voltage transformer while the current interrupt feature includes a control coil coupled to the controlling semiconductor and positioned close to the high voltage transformer to be influenced by the permanent magnet motion.

Claims4

Dependent claims

In an internal combustion engine ignition system of the type having a generally E-shaped magnetic core,

a spark coil with primary and secondary windings positioned on the center leg of the generally E-shaped magnetic core,
at least one spark plug connected to the secondary winding,
means for providing a magnetic field in the magnetic core for inducing a current flow in the primary winding, the magnetic field changing in synchronism with rotation of a part of the internal combustion engine, an improved ignition control circuit of the contactless interrupt type comprising:
a control circuit consisting of a control coil, a power transistor having a collector-emitter circuit connected across the primary winding, and a gate controlled switch connected in controlling relation to the transistor;
said control coil being in close proximity to the spark coil generally intermediate a pair of the E-shaped core legs and influenced by the means for providing a magnetic field to interrupt the magnetic field induced current in the primary winding near the time that current reaches a maximum value by disabling the gate controlled switch and therefore also the transistor and induce a spark creating voltage in the secondary winding.

2 more elements

Dependencies are inferred from the claim text.