초록 ▼

A unipolar ignition of the invention provides a current waveform at the ignitor plug which initially rises relatively slowly, followed by a transition to a fast rising current which quickly peaks and thereafter slowly dissipates. Such a current waveform provides an initially hotter and longer lastin

A unipolar ignition of the invention provides a current waveform at the ignitor plug which initially rises relatively slowly, followed by a transition to a fast rising current which quickly peaks and thereafter slowly dissipates. Such a current waveform provides an initially hotter and longer lasting spark which does not harm the ignitor plug of the system or shorten its life expectancy. Neither does the spark create stress on the solid state circuitry which delivers the energy to the ignitor plug. To provide the foregoing spark and current characteristics, an inductor having a saturable core is in series with the ignitor plug, and it provides an initially high inductance which limits the rate of current rise at the plug as energy is transferred from an energy storage device to the plug. As the current through the inductor increases, its core begins to saturate and the effective inductance begins to decrease, allowing the current to rise more quickly. As energy is transferred to the ignitor plug, the increasing saturation, decreasing inductance and increasing current complement one another, causing the rate of current rise to increase quickly to a high value desirable for ignition. Related features of the invention provide for easy diagnostics of the spark and for timing an ignition sequence and providing a repetition rate which aids in a successful ignition.

대표청구항 ▼

In a system for igniting fuel for a turbine engine, a unipolar ignition comprising: a voltage converter for receiving a low voltage from a system source and converting it to a high DC output voltage; a capacitor coupled to said voltage converter for accumulating energy delivered from said voltage co

In a system for igniting fuel for a turbine engine, a unipolar ignition comprising: a voltage converter for receiving a low voltage from a system source and converting it to a high DC output voltage; a capacitor coupled to said voltage converter for accumulating energy delivered from said voltage converter; an inductor wound about a magnetically saturable core and connected in series with a low tension ignitor plug; a unidirectional device connected in parallel with said series connected inductor and low tension ignitor plug for ensuring a unipolar current across the gap of the plug; solid state means including a switch means for transferring the energy accumulated by the capacitor to the series connected inductor and low tension ignitor plug such that the following sequence of event occurs: (a) a high voltage appears across the gap of the ignitor plug and begins to create a plasma, (b) a relatively slow current rise (di/dt) is initiated during transition of said switch means from a first state to a second state while sustaining the high voltage across the gap of the ignitor plug; (c) saturation of said magnetically saturable core occurs and a relatively fast di/dt occurs across the gap of low tension ignitor plug, thereby completing the generation of a spark across the gap; the saturable core having (1) a saturated inductance that provides the spark across the gap of the low tension ignitor plug with sufficient power to reliably ignite the fuel of the turbine engine (2) an unsaturated inductance that limits a current through the low tension ignitor plug and thereby protects the plug from excessive wear, and (3) a size sufficient to store the energy delivered from the capacitor to the inductor without saturating until after the plasma is formed.