Spark ignition transformer with a non-linear secondary current characteristic

Patent metadata

Field	Value
Publication number	US-10090099-B2
Application number	US-201514734374-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Jun 9, 2015
Publication date	Oct 2, 2018
Grant date	Oct 2, 2018

Abstract

An ignition transformer for use with a spark ignition system for an internal combustion engine includes a central core, a primary coil, a secondary coil, and a magnetic return. The central core defines a first end and a second end. The primary coil is used to vary magnetic energy into the central core in response to a primary current applied to the primary coil. The secondary coil is used to generate a secondary voltage in response to changes in the magnetic energy in the central core. The magnetic return defines a return-path to couple magnetic energy from the first end to the second end. A permeability value of the return-path is selected so the transformer has a secondary-current versus time-response characteristic that decays to fifty-percent (50%) of an initial secondary current when ten percent (10%) to twenty-five percent (25%) of a burn-time interval has passed.

First claim

We claim:

1. An ignition transformer for use with a spark ignition system for an internal combustion engine, said transformer comprising:
a central core that defines a first end and a second end;
a primary coil wound about the central core, wherein the primary coil is used to vary magnetic energy into the central core in response to a primary current applied to the primary coil;
a secondary coil wound about the central core, wherein the secondary coil is used to generate a secondary voltage in response to changes in the magnetic energy in the central core; and
a magnetic return that defines a return-path to couple magnetic energy from the first end to the second end, wherein a permeability value of the return-path is selected so the transformer has a secondary-current versus time-response characteristic that decays to fifty-percent (50%) of an initial secondary current when ten percent (10%) to twenty-five percent (25%) of a burn-time interval has passed.

2. The transformer in accordance with claim 1 , wherein the burn-time time interval occurs while the secondary voltage is 1000 volts.

3. The transformer in accordance with claim 1 , wherein the magnetic return is formed of a material characterized by a relative-permeability value between 10 and 1500.

4. The transformer in accordance with claim 3 , wherein the material comprises iron.

5. The transformer in accordance with claim 1 , wherein the return-path includes an air-gap.

6. The transformer in accordance with claim 5 , wherein a core area to air-gap size ratio is between 250 and 1500 mm.

Assignees

• Delphi Tech Ip Ltd

Inventors

• Skinner Albert A
• Levers Jr Harry O

Classifications

• H01F38/12 Primary

  Ignition, e.g. for IC engines · CPC title

• H01F27/255

  made from particles (H01F27/26 takes precedence) · CPC title

• H01F1/14

  metals or alloys · CPC title

• F02P9/002

  Control of spark intensity, intensifying, lengthening, suppression (by means of current control in the storage devices F02P3/05, F02P3/09, during starting F02P15/12) · CPC title

• F02P3/0442

  using digital techniques (F02P3/0456, F02P3/053, F02P3/0554, F02P3/0558 take precedence) · CPC title