Exhaust gas analyzer, and exhaust gas analysis method

Patent metadata

Field	Value
Publication number	US-11698338-B2
Application number	US-202016893924-A
Country	US
Kind code	B2
Filing date	Jun 5, 2020
Priority date	Jun 7, 2019
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

An exhaust gas analyzer to analyze exhaust gas discharged from an internal combustion engine includes an infrared light source, a photodetector, a CO2 concentration calculation part and an O2 concentration calculation part. The infrared light source irradiates infrared light to the exhaust gas. The photodetector detects infrared light after passing through the exhaust gas. The CO2 concentration calculation part calculates a CO2 concentration in the exhaust gas on the basis of a detection signal obtained by the photodetector. The O2 concentration calculation part calculates an O2 concentration in the exhaust gas from the CO2 concentration by using a fuel combustion reaction equation and an EGR rate in an exhaust gas recirculation system or a value related to the EGR rate.

First claim

What is claimed is:

1. An exhaust gas analyzer to analyze exhaust gas discharged from an internal combustion engine, comprising:
an infrared light source to irradiate infrared light to the exhaust gas;
a photodetector to detect the infrared light after passing through the exhaust gas;
a processor configured to calculate a CO 2 concentration in the exhaust gas on a basis of a detection signal obtained by the photodetector, and to calculate an O 2 concentration in the exhaust gas from the CO 2 concentration by using a fuel combustion reaction equation and an EGR rate in an exhaust gas recirculation system or a value related to the EGR rate such that the exhaust gas analyzer measures the O 2 concentration that does not absorb the infrared light, wherein the fuel combustion reaction equation indicates a relationship between CO 2 and H 2 O generated during fuel combustion; and
a catalyst disposed in an exhaust pipe connecting to the internal combustion engine so as to analyze exhaust gas after passing through the catalyst, wherein
the processor further calculates the O 2 concentration in the exhaust gas by using a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, a conversion coefficient obtained from a ratio of an O 2 coefficient and a CO 2 coefficient in the fuel combustion reaction equation, an EGR correction coefficient obtained from the EGR rate or a value related to the EGR rate, a catalyst correction coefficient obtained from a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, and a CO 2 concentration variation calculated by the processor.

2. The exhaust gas analyzer according to claim 1 , wherein the processor calculates the O 2 concentration according to a following equation:
[O 2 concentration]=[Original O 2 concentration]−[Conversion coefficient]×[EGR correction coefficient]×[CO 2 concentration variation].

3. The exhaust gas analyzer according to claim 1 , wherein the processor stores beforehand a relational expression indicating a relationship between the EGR rate or the value related to the EGR rate and the CO 2 concentration, and calculates the EGR correction coefficient from the CO 2 concentration by using the relational expression.

4. The exhaust gas analyzer according to claim 3 , wherein individual parameters of the relational expression are generated from training data comprising a previously acquired EGR rate or a value related to the previously acquired EGR rate and a previously acquired CO 2 concentration.

5. The exhaust gas analyzer according to claim 1 , wherein the processor calculates the O 2 concentration according to a following equation:
[O 2 concentration]=[Original O 2 concentration]−[Conversion coefficient]×[EGR correction coefficient]×[Catalyst correction coefficent]×[CO 2 concentration variation].

6. The exhaust gas analyzer according to claim 1 , wherein the processor stores beforehand a relational expression indicating a relationship between a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst and a CO 2 concentration, and calculates from the CO 2 concentration a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst by using the relational expression.

7. The exhaust gas analyzer according to claim 1 , wherein the processor calculates the CO 2 concentration in the exhaust gas using Fourier transform infrared spectroscopy.

8. An exhaust gas analysis method for analyzing exhaust gas discharged from an internal combustion engine via an exhaust pipe connected to the internal combustion engine and having a catalyst disposed therein, comprising:
irradiating infrared light to the exhaust gas;
detecting the infrared light after passing through the exhaust gas;
generating a detection signal on a basis of the detected infrared light;
calculating a carbon dioxide (CO 2 ) concentration in the exhaust gas on a basis of the detection signal; and
calculating an oxygen (O 2 ) concentration in the exhaust gas from the CO 2 concentration by using a fuel combustion reaction equation, an EGR rate in an exhaust gas recirculation system or a value related to the EGR rate, a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, a conversion coefficient obtained from a ratio of an O 2 coefficient and a CO 2 coefficient in the fuel combustion reaction equation, an EGR correction coefficient obtained from the EGR rate or a value related to the EGR rate, a catalyst correction coefficient obtained from a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, and a CO 2 concentration variation such that the O 2 concentration that does not absorb the infrared light is measured.

9. An exhaust gas analyzer to analyze exhaust gas discharged from an internal combustion engine, comprising:
an infrared light source to irradiate infrared light to the exhaust gas;
a photodetector to detect the infrared light after passing through the exhaust gas; and
a processor to calculate a CO 2 concentration in the exhaust gas on a basis of a detection signal obtained by the photodetector, and to calculate an O 2 concentration in the exhaust gas from pretrained data generated from training data comprising a CO 2 concentration and an O 2 concentration in the exhaust gas and expressing a correlation between the CO 2 concentration and the O 2 concentration in the exhaust gas, and from the CO 2 concentration calculated by the processor such that the exhaust gas analyzer measures the O 2 concentration that does not absorb the infrared light.

10. An exhaust gas analyzer to analyze exhaust gas discharged from an internal combustion engine, comprising:
an infrared light source to irradiate infrared light to the exhaust gas;
a photodetector to detect the infrared light after passing through the exhaust gas;
a processor to calculate a CO 2 concentration in the exhaust gas on a basis of a detection signal obtained by the photodetector, and to calculate an O 2 concentration in the exhaust gas from the CO 2 concentration by using a fuel combustion reaction equation and an EGR rate in an exhaust gas recirculation system or a value related to the EGR rate such that the exhaust gas analyzer measures the O 2 concentration that does not absorb the infrared light, wherein the fuel combustion reaction equation indicates a relationship between CO 2 and H 2 O generated during fuel combustion; and;
a catalyst disposed in an exhaust pipe connecting to the internal combustion engine so as to analyze exhaust gas after passing through the catalyst, wherein
the processor calculates the O 2 concentration in the exhaust gas by using a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, a conversion coefficient obtained from a ratio of an O 2 coefficient and a CO 2 coefficient in the fuel combustion reaction equation, an EGR correction coefficient obtained from the EGR rate or a value related to the EGR rate, a catalyst correction coefficient obtained from a value indicating an oxygen desorption amount or oxygen absorption amount by the catalyst, and a CO 2 concentration variation calculated by the processor.

Assignees

• Horiba Ltd

Inventors

• Mori Yuichi
• Yabushita Hirotaka

Classifications

• G01M15/108

  using optical methods · CPC title

• G01N33/004 Primary

  CO or CO2 · CPC title

• G01N2021/3595

  using FTIR · CPC title

• G01N21/3504 Primary

  for analysing gases, e.g. multi-gas analysis · CPC title

• F02D41/0072

  Estimating, calculating or determining the EGR rate, amount or flow (sensors in EGR systems F02M26/45) · CPC title