# US 8,783,220 B2 · Quarter wave coaxial cavity igniter for combustion engines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,783,220 B2 - Document ID: US8783220B2 - Status: Granted - Kind: B2 - Application number: 12/721,231 - Filed: 2010-03-10 - Published: 2011-06-23 - Granted: 2014-07-22 - Earliest claimed: 2008-01-31 - Assignees: West Virginia University - Applicants: James E. Smith; Franz A. Pertl - Inventors: James E. Smith; Franz A. Pertl - Web page: https://patentgrep.com/patent/US8783220B2 ## CPC - H01T 19/00: Devices providing for corona discharge (for charging electrographic elements G03G15/02) - F02P 9/007: {by supplementary electrical discharge in the pre-ionised electrode interspace of the sparking plug, e.g. plasma jet ignition} - F02P 23/045: {using electromagnetic microwaves} - H05H 1/46: using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) - F02P 3/01: 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) - H05H 2242/20: Power circuits - H01T: SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES (overvoltage protection circuits H02H) - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS ## Abstract An apparatus and method for igniting combustible materials in a combustion chamber of a combustion engine using corona discharge plasma from a quarter wave coaxial cavity resonator. A tapered quarter wave coaxial cavity resonator is adapted to mate with the combustion chamber. The quarter wave coaxial cavity resonator is coupled with an energy shaping means, or waveform generator, that develops the appropriate waveform for triggering radio frequency oscillations in the quarter wave coaxial cavity resonator. A loop coupling is angularly positioned within the quarter wave coaxial cavity resonator to match impedances between the quarter wave coaxial cavity resonator and the energy shaping means, or waveform generator. Radio frequency oscillations produce a standing wave in the quarter wave coaxial cavity resonator and a corona discharge plasma develops near the center conductor. The corona discharge plasma developed near the center conductor ignites the combustible materials in the combustion chamber of the combustion engine. ## Claims ### Claim 1 An ignition source for a combustible material in a combustion chamber of a combustion engine, comprising: a tapered quarter wave coaxial cavity resonator adapted to mate with the combustion engine, said taper quarter wave coaxial cavity resonator having a center conductor directed generally towards the combustion chamber when mated with the combustion engine; an energy shaping means operably coupled to said tapered quarter wave coaxial cavity resonator; and a connection means operably coupled to said energy shaping means for accepting an electrical stimulus from an ignition control system associated with the combustion engine, said electrical stimulus triggering a sustained RF oscillation between said energy shaping means and said tapered quarter wave coaxial cavity resonator such that an RF corona is formed near said center conductor which ionizes a portion of the combustible material in the combustion chamber causing ignition of the combustible material. ### Claim 2 (depends on 1) The ignition source of claim 1, wherein said tapered quarter wave coaxial cavity resonator has an internal cavity having a radius that becomes smaller at an end that is directed generally towards said combustion chamber. ### Claim 3 (depends on 2) The ignition source of claim 2, wherein a radius of said center conductor and said radius of said internal cavity are adapted to maintain an approximately constant ratio along a length of said tapered quarter wave coaxial cavity resonator. ### Claim 4 (depends on 1) The ignition source of claim 1, wherein said energy shaping means comprises a pulsed magnetron microwave supply and said tapered quarter wave coaxial cavity resonator is adapted to fit a spark plug socket. ### Claim 5 (depends on 1) The ignition source of claim 1, wherein said energy shaping means generates said RF oscillation and uses said tapered quarter wave coaxial cavity resonator as a frequency determining element in generating said RF oscillation. ### Claim 6 (depends on 5) The ignition source of claim 5, wherein a feedback means operably associated with said tapered quarter wave coaxial cavity resonator provides feedback to said energy shaping means. ### Claim 7 (depends on 6) The ignition source of claim 6, wherein said feedback means is selected from the group consisting of a probe, a pickup loop, and a waveguide. ### Claim 8 (depends on 1) The ignition source of claim 1, further comprising a loop coupling in said tapered quarter wave coaxial cavity resonator to couple said energy shaping means to said tapered quarter wave coaxial cavity resonator. ### Claim 9 (depends on 8) The ignition source of claim 8, wherein said loop coupling is angularly positioned within said tapered quarter wave coaxial cavity resonator to match approximately the impedance of said energy shaping means to said tapered quarter wave coaxial cavity resonator. ### Claim 10 (depends on 1) The ignition source of claim 1, wherein said energy shaping means is adapted to dynamically match an impedance of said tapered quarter wave coaxial cavity resonator. ### Claim 11 (depends on 1) The ignition source of claim 1, wherein said energy shaping means is selected from the group consisting of a negative resistance device, a negative resistance device is incorporated into said tapered quarter wave coaxial cavity resonator, an RF field effect transistor, spark gap, a pulse amplifying device, an electron tube, an electron drift tube, a traveling wave tube, an amplitron, and a magnetron. ### Claim 12 (depends on 1) The ignition source of claim 1, wherein said sustained RF oscillation is a continuous RF oscillation during a period of combustion. ### Claim 13 (depends on 1) The ignition source of claim 1, wherein said at least a portion of said tapered quarter wave coaxial cavity resonator is filled with a dielectric material.