Ignition circuit with piezoelectric transformer

• US 6,114,797 A
• Filed: 11/09/1999
• Issued: 09/05/2000
• Est. Priority Date: 05/27/1997
• Status: Expired due to Term

• Current Assignee: Face International Corp.
• Original Assignee: Face International Corp.
• Inventors: Boyd, Clark Davis, Bishop, Richard Patten
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/436,516
• Time in Patent Office: 301 Days
• Field of Search: 310/318, 310/316.01
• US Class Current: 310/318
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers
• CPC Class Codes: H10N 30/804 for piezoelectric transformers conversion of DC or AC power H02M; for operating discharge lamps H05B41/282

Abstract

Circuits for use in ignition systems are disclosed which use a resonating piezoelectric transformer along with complementary circuit components, to efficiently convert a DC first voltage to a transformer-output AC second voltage. In the preferred embodiment of the invention, a High Displacement Piezoelectric (HDP) transformer converts a DC voltage into an AC voltage which is rectified into a DC signal of sufficiently high voltage to create a spark across the spark gap of a spark plug. The transformer circuit may be a "self resonating" circuit which relies on an initial pulse from turning on the DC power supply to cause the transformer to begin resonating. In a modified circuit the circuit is not "self resonating" and instead has a phase shift oscillator sub-circuit that provides small pulse signals to start the transformer resonating when the circuit is initially turned on.

Claims

1. A spark discharge circuit, comprising:

a resonant sub-circuit;

said resonant sub-circuit comprising a transformer device;

said transformer device having an input portion and output portion;

said input portion comprising an electroactive layer disposed between a first electrode layer and a second electrode layer;

and said output portion comprising a third electrode layer adjacent an electroactive layer;

said resonant sub-circuit further comprising an inductor electrically connected in parallel with said input portion of said transformer device between said first electrode layer and said second electrode layer;

a first conductor adapted to be connected to a DC first voltage;

said first conductor being electrically connected to said first electrode layer and to a first end of said inductor;

a second conductor adapted to be connected to a DC second voltage, said DC first voltage being greater than said DC second voltage;

a switching device (Q1);

said switching device having a control input conductor (G), a first switch terminal (D) and a second switch terminal (S);

said first switch terminal (D) being electrically connected to said second electrode layer;

said second switch terminal (S) being electrically connected to said second conductor;

a first resistor electrically connected in parallel with said inductor;

said first resistor being electrically connected at a first end to said inductor and said first conductor and said first electrode;

and said first resistor being electrically connected at a second end to said control input conductor (G) of said switching device (Q1);

a second resistor electrically connected in parallel with said switching device (Q1);

said second resistor being electrically connected at a first end to said control input conductor (G) of said switching device (Q1);

and said second resistor being electrically connected at a second end to said second terminal (S) of said switching device (Q1);

a first output conductor electrically connected to said third electrode;

wherein a DC voltage potential applied between said first conductor and said second conductor

may be converted to an AC voltage potential between said first output conductor and first switch terminal (D);

a voltage rectifier for converting said AC voltage into a third DC voltage;

an input to said rectifier being said AC voltage potential between said first output conductor and said first terminal (D) of said switching device (Q1);

an output of said rectifier being a third DC voltage potential between a first and a second output terminal of said voltage rectifier;

a third conductor with first and second ends;

said first end of said third conductor being electrically connected to said first output terminal of said voltage rectifier; and

a fourth conductor with first and second ends;

said first end of said fourth conductor being electrically connected to said second output terminal of said voltage rectifier;

said second end of said third conductor and said second end of said fourth conductor defining a spark gap;

whereby said third DC voltage potential between said first and second output terminals of said voltage rectifier is sufficient to generate a spark across said spark gap.

2. A spark discharge circuit, comprising:

a resonant sub-circuit;

said resonant sub-circuit comprising a transformer device;

said transformer device having an input portion and output portion;

said input portion comprising an electroactive layer disposed between a first electrode layer and a second electrode layer;

and said output portion comprising a third electrode layer adjacent an electroactive layer;

said resonant sub-circuit further comprising an inductor electrically connected in parallel with said input portion of said transformer device between said first electrode layer and said second electrode layer;

a first conductor adapted to be connected to a DC first voltage;

said first conductor being electrically connected to said first electrode layer and to a first end of said inductor;

a second conductor adapted to be connected to a DC second voltage, said DC first voltage being greater than said DC second voltage;

a switching device (Q1),

said switching device having a control input conductor (G), a first switch terminal (D) and a second switch terminal (S);

said first switch terminal (D) being electrically connected to said second electrode layer;

said second switch terminal (S) being electrically connected to said second conductor;

a first resistor electrically connected in parallel with said inductor;

said first resistor being electrically connected at a first end to said inductor and said first conductor and said first electrode;

and said first resistor being electrically connected at a second end to said control input conductor (G) of said switching device (Q1);

a first output conductor electrically connected to said third electrode layer;

a second resistor electrically connected in parallel with said switching device (Q1) and said output portion of said transformer device;

said second resistor being electrically connected at a first end to said control input conductor (G) of said switching device (Q1), and said second resistor being electrically connected at a second end to said third electrode layer;

wherein a DC voltage potential applied between said first conductor and said second conductor may be converted to an AC voltage potential between said first output conductor and second resistor;

a voltage rectifier for converting said AC voltage into a third DC voltage;

an input to said rectifier being said AC voltage potential between said first output conductor and said second resistor;

an output of said rectifier being a third DC voltage potential between a first output terminal of said voltage rectifier and said second electrode layer;

a second output conductor with first and second ends;

said first end of said second output conductor being electrically connected to said second electrode layer;

a third conductor with first and second ends;

said first end of said third conductor being electrically connected to said first output terminal of said voltage rectifier; and

said second end of said second output conductor and said second end of said third conductor defining a spark gap;

whereby said third DC voltage potential between said first output terminal of said voltage rectifier and said second electrode layer is sufficient to generate a spark across said spark gap.

3. A spark discharge circuit, comprising:

a resonant sub-circuit;

said resonant sub-circuit comprising a transformer device;

said transformer device having an input portion, an output portion and an isolation layer;

said input portion comprising a first electroactive layer disposed between a first electrode layer and a second electrode layer;

said output portion comprising a second electroactive layer disposed between a third electrode layer and a fourth electrode layer;

and said isolation layer comprising a dielectric layer disposed between said second electrode layer and said third electrode layer

said resonant sub-circuit further comprising an inductor electrically connected in parallel with said input portion of said transformer device between said first electrode layer and said second electrode layer;

a first conductor adapted to be connected to a DC first voltage;

said first conductor being electrically connected to said first electrode layer and to a first end of said inductor;

a second conductor adapted to be connected to a DC second voltage, said DC first voltage being greater than said DC second voltage;

a switching device (Q1),

said switching device having a control input conductor (G), a first switch terminal (D) and a second switch terminal (S);

said first switch terminal (D) being electrically connected to said second electrode layer;

said second switch terminal (S) being electrically connected to said second conductor;

a first resistor electrically connected in parallel with said inductor;

said first resistor being electrically connected at a first end to said inductor and said first conductor and said first electrode;

and said first resistor being electrically connected at a second end to said control input conductor (G) of said switching device (Q1);

a first output conductor electrically connected to said fourth electrode layer;

a second output conductor electrically connected to said third electrode layer;

a second resistor electrically connected in parallel with said switching device (Q1) and said output portion of said transformer device;

said second resistor being electrically connected at a first end to said control input conductor (G) of said switching device (Q1);

and said second resistor being electrically connected at a second end to said third electrode layer;

wherein a DC voltage potential applied between said first conductor and said second conductor may be converted to an AC voltage potential between said first output conductor and second resistor;

a voltage rectifier for converting said AC voltage into a third DC voltage;

an input to said rectifier being said AC voltage potential between said first output conductor and said second resistor;

an output of said rectifier being a third DC voltage potential between a first and a second output terminal of said voltage rectifier;

a third conductor with first and second ends;

said first end of said third conductor being electrically connected to said first output terminal of said voltage rectifier; and

a fourth conductor with first and second ends;

said first end of said fourth conductor being electrically connected to said second output terminal of said voltage rectifier;

said second end of said third conductor and said second end of said fourth conductor defining a spark gap;

whereby said third DC voltage potential between said first and second output terminals of said voltage rectifier is sufficient to generate a spark across said spark gap.