Traveling spark ignition system

• US 5,704,321 A
• Filed: 10/11/1996
• Issued: 01/06/1998
• Est. Priority Date: 05/29/1996
• Status: Expired due to Term

• Current Assignee: Princeton University
• Original Assignee: The Trustees of Princeton University (Princeton University)
• Inventors: Suckewer, Szymon, Durbin, Enoch J.
• Primary Examiner(s): Nelli, Raymond A.
• Application Number:
  US08/730,685
• Time in Patent Office: 452 Days
• Field of Search: 123/143 B, 123/143 R, 123/146.5 R
• US Class Current: 123/143.00B
• CPC Class Codes: F02P 9/007 by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition
• CPC Class Codes: H01T 13/50 having means for ionisation of gap H01T13/52 takes precedence

Abstract

A plasma injector for an internal combustion engine, in one embodiment, includes two spaced apart and parallel donut shaped disk electrodes, between which a horizontally outward moving plasma is formed via a high voltage applied across the electrodes. The present invention is characterized by its efficient use of input electrical energy via electronic circuitry for driving the plasma injector. An ignition source provides an ignition plasma kernel which is several orders of magnitude larger than that produced by conventional spark plugs.

Use of very lean combustible mixtures, in which the dilution of the mixture is achieved by use of exhaust gas recirculation, is made possible by the present ignition system. Considerable improvement in engine efficiency, and a major reduction in NO_x exhaust gas pollutants are obtained via the present ignition.

Claims

1. A traveling spark ignition (TSI) system for a combustion engine, comprising:

an ignitor including;

parallel and spaced apart electrodes, including at least first and second electrodes forming a discharge gap between them, wherein the ratio of the sum of the radii of said electrodes to the length of the said electrodes is larger than or equal to 4, while the ratio of the difference of these two radii to the length of the said electrodes is larger than 1/3;

polarizable ceramic material surrounding a substantial portion of said electrodes and the space between said electrodes;

an uninsulated end portion of each of said electrodes being free of said polarizable ceramic material and in oppositional relationship to one another;

means for housing said first and second electrodes and associated said polarizable ceramic material, including means for mounting said ignitor with said free ends of said first and second electrodes installed in a combustion cylinder of said engine;

electrical means for providing a potential difference between said electrodes for initially providing thereto a sufficiently high first voltage for creating a channel formed of plasma between said electrodes, and thereafter a second voltage of lower potential than said first voltage, for sustaining a flow of current through the plasma in said channel between said electrodes, whereby an electric field from the potential difference between said electrodes and said magnetic field interact in a manner creating a force upon said plasma for causing it to move away from its points of origin, thereby substantially increasing the volume of said plasma.

2. The TSI system of claim 1, wherein said electrical means includes:

a first voltage source for providing said first voltage having a relatively high amplitude but low magnitude of current; and

a second voltage source for providing said second voltage of substantially lower amplitude but with higher magnitude of current relative to said first voltage source.

3. The TSI system of claim 1, further including:

said ignitor further including a third electrode located between said first and second electrodes; and

said first voltage is applied between said second and third electrodes, and said second voltage is applied between said first electrode and said second electrode.

4. The TSI system of claim 1, wherein said parallel first and second electrodes are parallel planar surfaces.

5. The TSI system of claim 1, wherein said parallel first and second electrodes are one or more pairs of parallel cylinders.

6. The TSI system of claim 1, wherein the axial length of the uninsulated portion of the first and second electrodes is smaller than or equal to 3 mm and the radial separation of the electrodes is from about 1 mm to about 3 mm.

7. The TSI system of claim 1, wherein said parallel first and second electrodes are parallel to the longitudinal axis of said ignitor.

8. The TSI system of claim 1, wherein uninsulated surfaces of the said parallel first and second electrodes that face each other are of the form of annular sections of disks oriented in a plane perpendicular to a longitudinal axis of said ignitor.

9. The TSI system of claim 8, wherein the radial width of said uninsulated part of annular disks is smaller or equal to 3 mm and the separation of the electrodes is about 1 mm to about 3 mm.

10. A traveling spark ignition (TSI) system for a combustion engine, comprising:

an ignitor including;

two parallel and spaced apart electrodes adapted for forming discharge gaps between them, wherein the radius of the largest cylinder which can fit between said electrodes is greater than the length of said electrodes;

polarizable ceramic material surrounding a substantial portion of said electrodes and the space between said electrodes;

an uninsulated end portion of each of said electrodes being free of said polarizable ceramic material and in oppositional relationship to one another, sand uninsulated end portion being designated the length of said electrodes, respectively;

means for housing said electrodes and associated said polarizable ceramic material, including means for mounting said ignitor with said free ends of said electrodes in a combustion cylinder of said engine; and

electrical means for sequentially providing two potential differences between said electrodes, the first potential difference applied being sufficiently high for creating a channel formed of plasma between said electrodes, and thereafter the second voltage applied of lower potential than said first voltage, for sustaining a flow of current through the plasma in said channel between said electrodes, whereby an electric field caused by the potential difference between said electrodes, and a magnetic field surrounding said current, interact in a manner creating a force upon said plasma for causing it to move away from its points of origin, thereby substantially increasing the swept area of said plasma.