Gas concentration estimation device

Patent metadata

Field	Value
Publication number	US-10078053-B2
Application number	US-201214369020-A
Country	US
Kind code	B2
Filing date	Dec 26, 2012
Priority date	Dec 28, 2011
Publication date	Sep 18, 2018
Grant date	Sep 18, 2018

Abstract

The present invention aims at realizing a gas concentration estimation apparatus with versatility wherein the gas concentration estimation apparatus estimates concentration of a target component in an analyte gas by analyzing a light emitted from plasma of the analyte gas. The present invention is directed to a gas concentration estimation apparatus including: a plasma generation device that turns an analyte gas into a plasma state; and an analysis device that analyzes plasma light emitted from the plasma generated by the plasma generation device and estimates concentration of a target component in the analyte gas wherein the analysis device estimates the concentration of the target component based on luminescence intensity of a wavelength component corresponding to luminescence from a predetermined radical within the plasma light, and the predetermined radical is different in atomic structure from the target component and includes an atom or a molecule separated from the target component.

First claim

What is claimed is:

1. A gas concentration estimation apparatus, comprising:
an exhaust pipe of an engine, an exhaust gas flowing from the engine into the exhaust pipe;
a plasma generation unit provided to the exhaust pipe and configured to turn the exhaust gas into a plasma state in the exhaust pipe;
an analysis unit that estimates concentration of a target component in the exhaust gas by analyzing plasma light emitted from the plasma generated by the plasma generation unit, wherein
the analysis unit is adapted to estimate the concentration of the target component based on luminescence intensity of a wavelength component corresponding to luminescence from a predetermined radical within the plasma light, the predetermined radical being different in atomic structure from the target component and including an atom or a molecule separated from the target component,
an exhaust gas emitted after combustion of hydrocarbon is regarded as the exhaust gas and carbon dioxide in the exhaust gas is regarded as the target component, and
the analysis unit is adapted to estimate unburned hydrocarbon concentration in the exhaust gas, and to correct, using the estimated unburned hydrocarbon concentration, the carbon dioxide concentration estimated based on the luminescence intensity of the wavelength component corresponding to the luminescence from the CN radical.

2. The gas concentration estimation apparatus according to claim 1 , wherein
the analysis unit is adapted to estimate concentration of carbon dioxide as the target component based on luminescence intensity of a wavelength component corresponding to luminescence from the CN radical within the plasma light.

3. The gas concentration estimation apparatus according to claim 1 , wherein
the analysis unit is adapted to estimate the unburned hydrocarbon concentration based on the luminescence intensity of the wavelength component corresponding to the luminescence from CH radical within the plasma light.

4. The gas concentration estimation apparatus according to claim 2 , wherein
the analysis unit is adapted to estimate the carbon dioxide concentration from the luminescence intensity of the wavelength component corresponding to the luminescence from the CN radical based on a calibration curve indicative of relationship between the carbon dioxide concentration and the luminescence intensity of the wavelength component corresponding to the luminescence from the CN radical.

5. The gas concentration estimation apparatus according to claim 1 , wherein
the analysis unit is adapted to estimate concentration of water vapor as the target component based on the luminescence intensity of the wavelength component corresponding to the luminescence from OH radical within the plasma light.

6. The gas concentration estimation apparatus according to claim 1 , wherein
the gas concentration estimation apparatus is further configured to detect a flow rate of the exhaust gas flowing into a plasma region in which the plasma generation unit generates the plasma, and
the analysis unit is adapted to correct, based on the flow rate detected by the gas concentration estimation apparatus, the concentration of the target component estimated based on the luminescence intensity of the wavelength component corresponding to the luminescence from the predetermined radical.

7. The gas concentration estimation apparatus according to claim 1 , wherein
the gas concentration estimation apparatus further includes a shield member provided upstream of a plasma region in which the plasma generation unit generates the plasma with respect to a flowing direction of the exhaust gas, and adapted to partially shield the plasma region.

8. The gas concentration estimation apparatus according to claim 7 , wherein
the analysis unit is adapted to analyze the plasma light extracted from a region not shielded by the shield member within the plasma region, and to estimate the concentration of the target component in the exhaust gas.

9. The gas concentration estimation apparatus according to claim 1 , wherein the plasma generation unit comprises a high voltage pulse generator and a microwave generator.

10. A gas concentration estimation method, comprising:
a step of generating an exhaust gas in an engine, the exhaust gas flowing from the engine into an exhaust pipe of the engine;
a plasma generation step of turning the exhaust gas into a plasma state in the exhaust pipe;
and
an analysis step of analyzing a plasma light emitted from plasma generated in the plasma generation step, and estimating concentration of a target component in the exhaust gas, wherein
in the analysis step, the concentration of the target component is estimated based on luminescence intensity of a wavelength component corresponding to luminescence from a predetermined radical within the plasma light, the predetermined radical being different in atomic structure from the target component and including an atom or a molecule separated from the target component,
an exhaust gas emitted after combustion of hydrocarbon is regarded as the exhaust gas and carbon dioxide in the exhaust gas is regarded as the target component, and
the analysis step comprises estimating unburned hydrocarbon concentration in the exhaust gas and correcting, using the estimated unburned hydrocarbon concentration, the carbon dioxide concentration estimated based on the luminescence intensity of the wavelength component corresponding to the luminescence from the CN radical.

Assignees

• Imagineering Inc

Inventors

• Ikeda Yuji

Classifications

• G01N2201/067

  Electro-optic, magneto-optic, acousto-optic elements · CPC title

• G01N33/0062

  concerning the measuring method or the display, e.g. intermittent measurement or digital display · CPC title

• G01N33/004

  CO or CO2 · CPC title

• G01N21/68 Primary

  using high frequency electric fields · CPC title

• G01N2021/8578

  Gaseous flow · CPC title