초록 ▼

The invention relates to a system for igniting a fuel-air mixture in a combustion chamber with a corona discharge. The system comprises an electrode inside of the combustion chamber, an electric circuit which provides radio frequency electric power to the electrode, and a ground formed by the combus

The invention relates to a system for igniting a fuel-air mixture in a combustion chamber with a corona discharge. The system comprises an electrode inside of the combustion chamber, an electric circuit which provides radio frequency electric power to the electrode, and a ground formed by the combustion chamber walls. A radio frequency voltage differential formed between the electrode and the ground produces a radio frequency electric field therebetween which causes a fuel-air mixture to ionize resulting in combustion of the fuel-air mixture. The system can be utilized in engines such as internal combustion engines or gas turbine engines, for example.

대표청구항 ▼

1. A system for igniting a fuel-air mixture in a combustion chamber having combustion chamber walls, the system comprising:an electrode inside of the combustion chamber; an electric circuit delivering radio frequency electric power at a frequency of between 30,000 and 3,000,000 hertz to the electrod

1. A system for igniting a fuel-air mixture in a combustion chamber having combustion chamber walls, the system comprising:an electrode inside of the combustion chamber; an electric circuit delivering radio frequency electric power at a frequency of between 30,000 and 3,000,000 hertz to the electrode; a ground formed at least in part by the combustion chamber walls; and means for controlling an output of the electric circuit to the electrode so that complete dielectric breakdown does not occur and so that an electric arc is not struck in the combustion chamber; wherein a radio frequency voltage differential formed between the electrode and the ground produces a radio frequency electric field therebetween which causes a fuel-air mixture to ionize resulting in combustion of the fuel-air mixture. 2. The system of claim 1, wherein the combustion chamber walls are formed by a cylinder and a reciprocating piston received in the cylinder that is driven by expanding combustion gases in the combustion chamber.3. The system of claim 1, wherein the combustion chamber is adapted for use in a gas turbine.4. The system of claim 1, wherein the electric circuit comprises a low voltage circuit and a high voltage circuit, the low voltage circuit driving the high voltage circuit through a radio frequency step-up transformer, the high voltage circuit having a resonant frequency and the low voltage circuit driving the high voltage circuit at or near its resonant frequency, the electrode being connected to an output of the high voltage circuit.5. The system of claim 1, wherein the electrode is directly exposed to an interior of the combustion chamber.6. The system of claim 1, wherein the electrode is surrounded by a dielectric material inside the combustion chamber.7. The system of claim 2, wherein the piston comprises means for directing the radio frequency electric field.8. The system of claim 1, wherein the electrode comprises a plurality of protrusions which direct the radio frequency electric field.9. A system for igniting a fuel-air mixture in a combustion chamber having combustion chamber walls, the system comprising:an electrode inside of the combustion chamber; an electric circuit delivering radio frequency electric power at a frequency of between 30,000 and 3,000,000 hertz to the electrode; a ground formed at least in part by the combustion chamber walls; and means for controlling an output of the electric circuit to the electrode so that complete dielectric breakdown does not occur and so that an electric arc is not struck in the combustion chamber; wherein a radio frequency voltage differential formed between the electrode and the ground produces a radio frequency electric field therebetween which causes a fuel-air mixture to ionize resulting in combustion of the fuel-air mixture; and wherein the electric circuit comprises a low voltage circuit and a high voltage circuit, the low voltage circuit driving the high voltage circuit through a radio frequency step-up transformer, the high voltage circuit having a resonant frequency and the low voltage circuit driving the high voltage circuit at or near its resonant frequency, the electrode being connected to an output of the high voltage circuit; and wherein the means for controlling the output of the electric circuit to the electrode measures an actual impedance in the electrical circuit and compares the actual impedance to a setpoint impedance. 10. The system of claim 9, wherein the means for controlling the output of the electric circuit to the electrode adjusts the power output of the high voltage circuit so that the actual impedance substantially corresponds to the setpoint impedance.11. The system of claim 10 wherein the means for controlling the output of the electric circuit to the electrode adjusts the power output of the high voltage circuit by using pulse width modulation to adjust the power output from the low voltage circuit.12. An apparatus comprising:an electrode adapted to be fixed within a combustion chamber; and a circuit for providing radio frequency power having a frequency of between 30,000 and 3,000,000 hertz to the electrode in a manner such that the radio frequency power creates a corona discharge in a gas within the combustion chamber, and wherein the circuit maintains a current between the electrode and a ground such that an electric arc is not formed in the combustion chamber between the electrode and the ground. 13. A method of igniting a combustible gaseous mixture in a combustion chamber comprising:discharging electric energy through an electrode with a corona discharge into a combustion chamber filled with combustible gaseous mixture; causing the combustible gaseous mixture to ionize due to the corona discharge to a sufficient level of ionization that the ionized combustible gaseous mixture commences a self-sustaining combustion reaction that combusts the combustible gaseous mixture in the combustion chamber; measuring an actual impedance of a circuit that provides power to the electrode; comparing the actual impedance with a setpoint impedance; and controlling a rate of discharge of electric energy through the electrode to cause the actual impedance to substantially match the setpoint impedance such that a plasma is not created and an electric arc is not struck in the combustion chamber. 14. The method of claim 13, wherein the step of discharging electric energy into the combustion chamber filled with the combustible gaseous mixture comprises generating a radio frequency electric field in the combustion chamber.15. The method of claim 13, wherein the electrode is powered by a high voltage circuit, and the high voltage circuit is powered by a low voltage circuit, the high voltage circuit having a resonant frequency, and the low voltage circuit powering the high voltage circuit through an RE step-up transformer that drives the high voltage circuit at or near its resonant frequency so that the high voltage circuit resonates, the electrode being connected to an output of the high voltage circuit.16. The method of claim 14, wherein the radio frequency electric field is generated between the electrode and field intensifiers formed in the combustion chamber, the field intensifiers acting to focus the strength of the electric field.17. The method of claim 15, wherein the impedance is measured at the input of the high voltage circuit.18. The method of claim 15, wherein the step of controlling the rate of discharge comprises adjusting the power output of the low voltage circuit using pulse width modulation.19. The method of claim 13, wherein the electrode is capacitively coupled to the combustion chamber.20. The method of claim 13, wherein the electrode is directly coupled to the combustion chamber.21. The method of claim 13, wherein the combustion chamber is adapted for use in an internal combustion engine.22. The method of claim 13, wherein the combustion chamber is adapted for use in a gas turbine engine.23. A method of igniting a combustible gaseous mixture in a combustion chamber comprising the steps of:providing radio frequency power to an electrode such that a corona discharge is generated between the electrode and the combustion chamber; measuring a voltage and a current of a power source which powers the electrode; and controlling a power level provided to the electrode based on the measured voltage and current to sustain the corona discharge between the electrode and the combustion chamber, wherein the corona discharge provides sufficient energy to ignite the combustible gaseous mixture in the combustion chamber. 24. The method of claim 23, wherein the radio frequency power has a frequency of between 30,000 and 3,000,000 hertz.25. The method of claim 23, further comprising the step of sustaining the corona discharge for a predetermined duration.26. The method of claim 25, wherein the predetermined duration is at least one millisecond.27. The method of claim 23, wherein the step of controlling the power level provided to the electrode comprises modulating a pulse width of a signal output from the power source.28. The method of claim 23, wherein the power source powers an LC circuit which resonates to power the electrode.29. The method of claim 28, wherein the step of controlling the power level provided to the electrode comprises controlling a frequency of a signal which drives the LC circuit.30. The method of claim 28, wherein the step of controlling the power level provided to the electrode comprises controlling at least one component value of a component in the LC circuit.31. The method of claim 23, wherein the combustion chamber is part of an internal combustion engine.32. The method of claim 23, wherein the combustion chamber is part of a gas turbine engine.33. A method of igniting a combustible gaseous mixture in a combustion chamber comprising the steps of:providing radio frequency power to an electrode such that a corona discharge is generated between the electrode and the combustion chamber; measuring a voltage and a current of a power source which powers the electrode; and controlling a power level provided to the electrode based on the measured voltage and current to sustain the corona discharge between the electrode and the combustion chamber, wherein the corona discharge provides sufficient energy to ignite the combustible gaseous mixture in the combustion chamber; wherein the power level provided to the electrode is controlled to prevent a plasma arc from forming between the electrode and the combustion chamber. 34. A method of igniting a combustible gaseous mixture in a combustion chamber comprising the steps of:providing radio frequency power to an electrode such that a corona discharge is generated between the electrode and the combustion chamber; measuring a voltage and a current of a power source which powers the electrode; controlling a power level provided to the electrode based on the measured voltage and current to sustain the corona discharge between the electrode and the combustion chamber, wherein the corona discharge provides sufficient energy to ignite the combustible gaseous mixture in the combustion chamber; calculating an actual impedance from the measured voltage and current; comparing the actual impedance to an impedance setpoint; and controlling the power level provided to the electrode to cause the actual impedance to substantially match the impedance setpoint. 35. An engine comprising:a combustion chamber for containing a combustible gaseous mixture; an electrode; a power source which powers the electrode; a current sensor which measures a current in the power source; a voltage sensor which measures a voltage in the power source; and means for controlling a power level provided to the electrode based on the measured voltage and current to sustain a corona discharge between the electrode and the combustion chamber, wherein the corona discharge provides sufficient energy to ignite the combustible gaseous mixture. 36. The engine of claim 35, wherein the electrode provides radio frequency power to the combustion chamber with a frequency of between 30,000 and 3,000,000 hertz.37. The engine of claim 35, wherein the engine is an internal combustion engine.38. The engine of claim 35, wherein the engine is a gas turbine engine.39. The engine of claim 35, wherein at least one of the electrode and the combustion chamber comprises a field enhancing device.40. The engine of claim 35, wherein the power source powers an LC circuit having a resonant frequency, and the electrode is connected to an output of the LC circuit.41. The engine of claim 35, wherein the means for controlling comprises a pulse width modulator which modulates a pulse width of an output signal from the power source.42. The engine of claim 40, wherein the means for controlling controls an output frequency of the power source which drives the LC circuit.43. An engine comprising:a combustion chamber for containing a combustible gaseous mixture; an electrode; a power source which powers the electrode; a current sensor which measures a current in the power source; a voltage sensor which measures a voltage in the power source; and means for controlling a power level provided to the electrode based on the measured voltage and current to sustain a corona discharge between the electrode and the combustion chamber, wherein the corona discharge provides sufficient energy to ignite the combustible gaseous mixture, wherein the means for controlling a power level prevents the formation of a plasma and an electric arc in the combustion chamber.