Fairchild Camera and Instrument Corp.

Lawrence M Blaser

Leonard E Arguello

Nicky Miles Johnson

Verne H Wilson

A digital and linear dynamic ignition control apparatus comprising a burn-time counter, a pre-dwell counter, a current limit counter, engine speed detection apparatus, a biasing circuit and an excess current limit circuit is provided for controlling the start of a dwell in each ignition period. In operation, a current limit adjust window is established for each period. The time of the termination of a dwell in the period relative to the current limit adjust window established for the period starts the dwell in the next period relative to the beginning of the next period at a time calculated to optimize engine performance and minimize energy losses. In general, rapid acceleration in a period starts the dwell earlier in the next period to insure adequate charging of the ignition coil. Conversely, rapid deceleration in a period starts the dwell later in the next period to minimize energy losses.

Dynamic ignition apparatus

An electronic advance and ignition control system incorporating the advance utilizes a fixed advance threshold compared with amplitude of an RPM sensitive input waveform from a distributor in combination with a timing circuit, which establishes a predetermined RPM rate above which the advance operates. The electronic advance accurately duplicates the function of conventional centrifugal and vacuum and advance retard mechanisms in controlling timing of an ignition coil drive signal. The electronic advance is provided as part of an ignition control integrated circuit which can operate in a stand alone mode or share control of the ignition system with a microprocessor through interface circuits also forming part of the integrated circuit.

Ignition control system with electronic advance

An ignition control system typically used with an automobile engine provides tight feedback control on engine timing. An integrator produces a waveform which is typically dual-slope in response to a timing signal supplied by a sensor responsive to rotation of a distributor. A dwell-control circuit produces a dwell-control reference signal which varies with the integrator waveform voltage at low engine speed. A comparator generates an output drive-control signal when the integrator waveform voltage equals or is less than the dwell-control reference voltage. An output drive circuit produces an activation signal in response to the drive-control signal to activate an output drive circuit which then supplies an ignition signal to an ignition coil. A feedback loop between the output drive circuit and the output drive-control circuit causes the output drive circuit to stabilize at a selected state such as a specified output current level. A feedback loop between the output drive circuit and the dwell-control circuit controls the level of the dwell-control reference voltage and thereby controls the dwell period.

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Mountain View, CA, United States of America

Lawrence M Blaser