Ionization detector with ignition coil inductance shorting
AssigneeBoard of Trustees of Michigan State University
InventorsGuoming G. Zhu, Kevin D. Moran
Life of this patent
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Abstract
An ionization detector that reduces the filtering effects of the ignition coil inductances by shorting an inductance of a primary winding of the ignition coil. The ionization detector includes a bias voltage source and an inductance control switch. The bias voltage source supplies electric voltage across an electric gap of a spark plug for detecting ionization within the combustion chamber. The inductance control switch is electrically parallel with a primary winding of an ignition coil and is operable to short an inductance of the primary winding.
Claims18
An ionization detector apparatus for detecting ionization of gases, the apparatus comprising:
- a coil having a primary winding and a secondary winding;
- a bias voltage source electrically coupled to the secondary winding, wherein the bias voltage source supplies electric voltage across an electrical gap by way of the secondary winding such that an ionization current flows across the electrical gap in response to ionized gas being present;
- an inductance control switch positioned electrically parallel with the primary winding of the coil and operable to short an inductance of the primary winding, wherein the inductance control switch includes a plurality of transistors;
- and
- a current sensor outputting a signal indicative of the ionization current flowing from the bias voltage source to the electrical gap, wherein the current sensor comprises a current mirror circuit.
A spark-ignition system comprising:
- a spark plug having an electrical gap and operable to generate an electric spark for igniting gas;
- an ignition coil including a primary winding and a secondary winding, wherein the ignition coil is operable to generate an electric current that arcs across the electric gap of the spark plug to generate the electric spark;
- an ionization detector sensing an ionization current after gases are ignited and including a bias voltage source and an inductance control switch, wherein the bias voltage source is electrically coupled to the secondary winding of the ignition coil and the inductance control switch is electrically parallel with the primary winding and is operable to short an inductance of the ignition coil, and wherein the inductance control switch includes a plurality of transistors;
- and
- a current sensor outputting a signal indicative of the ionization current flowing from the bias voltage source to the electrical gap, wherein the current sensor comprises a current mirror circuit.
A method for operating a spark-ignition system, the method comprising:
- building magnetic energy between a primary winding and a secondary winding of an ignition coil;
- releasing the magnetic energy through the secondary winding such that an electric current arcs across an electrical gap of a spark plug to ignite an air-fuel mixture;
- shorting an inductance of the ignition coil after the air-fuel mixture is ignited by activating a plurality of transistors positioned electrically parallel with the primary winding of the ignition coil such that the transistors short an inductance of the primary winding;
- measuring an ionization current flowing from a bias voltage source to the spark plug, wherein the bias voltage source is electrically coupled to the spark plug by way of the secondary winding such that the secondary winding is disposed between the spark plug and the bias voltage source;
- and
- outputting a signal indicative of the ionization current flowing from the bias voltage source to the electrical gap.
Dependencies are inferred from the claim text.