Compact electromagnetic plasma ignition device

Patent metadata

Field	Value
Publication number	US-10001105-B2
Application number	US-201715454429-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Jan 31, 2008
Publication date	Jun 19, 2018
Grant date	Jun 19, 2018

Abstract

A quarter wave coaxial cavity resonator for producing corona discharge plasma from is presented. The quarter wave coaxial cavity resonator has a folded cavity made of opposing concentric cavity members that are nested together to form a continuous cavity ending in a aperture. A center conductor with a tip is positioned in the cavity. The folded cavity advantageously permits the coaxial cavity resonator to resonate at a lower operating frequency than an unfolded quarter wave coaxial cavity resonator of the same length. Embodiments of the quarter wave coaxial cavity resonator use narrower apertures to reduce radiative losses, and include center conductors that are reactive load elements, such as helical coils. When a radio frequency (RF) oscillation is produced in the quarter wave coaxial cavity resonator, corona discharge plasma is formed at the tip of the center conductor. The corona discharge plasma can be used to ignite combustible materials in combustion chambers of combustion engines.

First claim

What is claimed is:

1. A quarter wave coaxial cavity resonator, comprising:
a plurality of concentric nested cavity members arranged to form a folded cavity, the plurality of concentric nested cavity members including an outer cavity member and an inner cavity member defining an aperture, the aperture having a radius that is less than a radius of the base outer cavity member; and
a center conductor including a tip, at least a portion of the center conductor disposed in the folded cavity, wherein an RF corona is formed in a region near the tip of the center conductor when a sustained RF oscillation of an operating wavelength is produced in the quarter wave coaxial cavity resonator and the radius of the tip is smaller than the operating wavelength.

2. The quarter wave coaxial cavity resonator of claim 1 , further comprising a threaded body surrounding the aperture and adapted to fit a spark plug socket.

3. The quarter wave coaxial cavity resonator of claim 1 , further comprising a dielectric seal positioned about the center conductor.

4. The quarter wave coaxial cavity resonator of claim 1 , wherein the tip is generally cylindrical.

5. The quarter wave coaxial cavity resonator of claim 1 , wherein the tip is generally spherical.

6. The quarter wave coaxial cavity resonator of claim 1 , wherein the tip is curved.

7. The quarter wave coaxial cavity resonator of claim 1 , wherein the tip includes a point.

8. The quarter wave coaxial cavity resonator of claim 1 , wherein the tip is generally teardrop shaped.

9. The quarter wave coaxial cavity resonator of claim 1 , further comprising a loop coupling to couple an energy shaping circuit to the center conductor of the quarter wave coaxial cavity resonator.

Assignees

• Univ West Virginia

Inventors

• Smith James E
• Pertl Franz A

Classifications

• H01T9/00

  Spark gaps specially adapted for generating oscillations · CPC title

• H01T19/00

  Devices providing for corona discharge (for charging electrographic elements G03G15/02) · CPC title

• F02P9/007 Primary

  by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition · CPC title

• F02P3/01

  Electric spark ignition installations without subsequent energy storage, i.e. energy supplied by an electrical oscillator (with magneto- or dynamo-electric generators F02P1/00; piezoelectric ignition F02P3/12; with continuous electric spark F02P15/10) · CPC title

• F02P23/045

  using electromagnetic microwaves · CPC title