Method of measuring a gas component and sensing device for measuring the gas component

Claim 1

A method of measuring a concentration of NOx in a measurement gas, comprising the steps of: introducing the measurement gas containing NOx into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen; and measuring a concentration of the oxygen produced by reduction or decomposition of NO in the internal chamber.

Claim 2

A method of measuring a concentration of NOx in a measurement gas, comprising the steps of: introducing the measurement gas containing NOx into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen; and measuring a concentration of the oxygen produced by reduction or decomposition of NO in the internal chamber.

Claim 6

A method of measuring a concentration, Cn, of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen; pumping out the oxygen produced by reduction or decomposition of NO by an oxygen pumping action of an electrochemical cell; detecting a pumping current, Ip3, flowing through the electrochemical cell; and calculating the concentration, Cn, of NO present in the atmosphere in the internal chamber, on the basis of said pumping current, Ip3, according to the following equation: Cn=K·Ip3-A wherein K is a current sensitivity coefficient, and A is a constant indicative of a small amount of oxygen remaining in the internal chamber.

Claim 7

A method of measuring a concentration, Cn, of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen; pumping out the oxygen produced by reduction or decomposition of NO by an oxygen pumping action of an electrochemical cell; detecting a pumping current, Ip3, flowing through the electrochemical cell; and calculating the concentration, Cn, of NO present in the atmosphere in the internal chamber, on the basis of said pumping current, Ip3, according to the following equation: Cn=K·Ip3-A wherein K is a current sensitivity coefficient, and A is a constant indicative of a small amount of oxygen remaining in the internal chamber.

Claim 10

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; oxidizing unburned components of the measurement gas in the internal chamber; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in the atmosphere in the internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber.

Claim 11

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; oxidizing unburned components of the measurement gas in the internal chamber; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in the atmosphere in the internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber.

Claim 14

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in the atmosphere in the internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber; wherein the oxygen partial pressure in the internal chamber is controlled by an oxygen partial-pressure detector and an electrochemical pumping cell; the oxygen partial-pressure detector comprising a first oxygen-ion conductive solid electrolyte which at least defines the internal chamber and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said oxygen partial-pressure detector generating an electromotive force corresponding to a difference between the oxygen partial pressure within the internal chamber and an oxygen partial pressure outside the internal chamber; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the internal chamber and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical pumping cell pumping oxygen into or out of the internal chamber; and a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said oxygen partial-pressure detector coincides with a predetermined value.

Claim 15

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in the atmosphere in the internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber; wherein the oxygen partial pressure in the internal chamber is controlled by an oxygen partial-pressure detector and an electrochemical pumping cell; the oxygen partial-pressure detector comprising a first oxygen-ion conductive solid electrolyte which at least defines the internal chamber and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said oxygen partial-pressure detector generating an electromotive force corresponding to a difference between the oxygen partial pressure within the internal chamber and an oxygen partial pressure outside the internal chamber; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the internal chamber and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical pumping cell pumping oxygen into or out of the internal chamber; and a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said oxygen partial-pressure detector coincides with a predetermined value.

Claim 25

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in said atmosphere in said internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber; wherein the oxygen partial pressure in the internal chamber is controlled by an electrochemical sensing cell and an electrochemical pumping cell; said electrochemical sensing cell comprising a first oxygen-ion conductive solid electrolyte which at least defines the internal chamber and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical sensing cell generating an electromotive force corresponding to a difference between the oxygen partial pressure within the internal chamber and an oxygen partial pressure outside the internal chamber; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the internal chamber and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical pumping cell pumping oxygen into or out of the internal chamber; a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said electrochemical sensing cell coincides with a predetermined value; and a concentration of oxygen in said measurement gas being measured on the basis of a pumping current flowing through said electrochemical pumping cell.

Claim 26

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into an internal chamber under a diffusion resistance; controlling an oxygen partial pressure in the internal chamber to a level which does not substantially decompose NO; and measuring the concentration of NO present in said atmosphere in said internal chamber by (i) exposing the atmosphere in the internal chamber to a NOx decomposition catalyst to reduce or decompose NO present in the atmosphere so as to produce oxygen, and (ii) measuring the oxygen partial pressure in the internal chamber; wherein the oxygen partial pressure in the internal chamber is controlled by an electrochemical sensing cell and an electrochemical pumping cell; said electrochemical sensing cell comprising a first oxygen-ion conductive solid electrolyte which at least defines the internal chamber and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical sensing cell generating an electromotive force corresponding to a difference between the oxygen partial pressure within the internal chamber and an oxygen partial pressure outside the internal chamber; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the internal chamber and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the internal chamber, respectively, said electrochemical pumping cell pumping oxygen into or out of the internal chamber; a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said electrochemical sensing cell coincides with a predetermined value; and a concentration of oxygen in said measurement gas being measured on the basis of a pumping current flowing through said electrochemical pumping cell.

Claim 27

A method of measuring a concentration, Cn, of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; reducing or decomposing NO present in the atmosphere in the second internal space to produce oxygen; pumping out the oxygen produced by reduction or decomposition of NO, by an oxygen pumping action of an electrochemical cell; detecting a pumping current, Ip3, flowing through the electrochemical cell; and calculating the concentration, Cn, of NO present in the atmosphere in the second internal space, on the basis of the pumping current, Ip3, according to the following equation: Cn=K·Ip3-A wherein K is a current sensitivity coefficient, and A is a constant indicative of a small amount of oxygen remaining in said first internal space.

Claim 28

A method of measuring a concentration, Cn, of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; reducing or decomposing NO present in the atmosphere in the second internal space to produce oxygen; pumping out the oxygen produced by reduction or decomposition of NO, by an oxygen pumping action of an electrochemical cell; detecting a pumping current, Ip3, flowing through the electrochemical cell; and calculating the concentration, Cn, of NO present in the atmosphere in the second internal space, on the basis of the pumping current, Ip3, according to the following equation: Cn=K·Ip3-A wherein K is a current sensitivity coefficient, and A is a constant indicative of a small amount of oxygen remaining in said first internal space.

Claim 30

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; oxidizing unburned components of said measurement gas in the first internal space; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in the atmosphere in the second internal space by (i) reducing or decomposing NO present in the atmosphere in the second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in the second internal space.

Claim 31

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; oxidizing unburned components of said measurement gas in the first internal space; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in the atmosphere in the second internal space by (i) reducing or decomposing NO present in the atmosphere in the second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in the second internal space.

Claim 34

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in the atmosphere in the second internal space by (i) reducing or decomposing NO present in the atmosphere in said second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in the second internal space; wherein said oxygen partial pressure in said first internal space is controlled by an oxygen partial-pressure detector and an electrochemical pumping cell; said oxygen partial-pressure detector comprising a first oxygen-ion conductive solid electrolyte which at least defines the first internal space and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the first internal space, respectively, said oxygen partial-pressure detector generating an electromotive force corresponding to a difference between the oxygen partial pressure within the first internal space and an oxygen partial pressure outside the first internal space; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the first internal space and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the first internal space, respectively, said electrochemical pumping cell pumping oxygen into or out of the first internal space; and a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that the electromotive force generated by the oxygen partial-pressure detector coincides with a predetermined value.

Claim 35

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in the first internal space to a level which does not substantially decompose NO; introducing an atmosphere in the first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in the atmosphere in the second internal space by (i) reducing or decomposing NO present in the atmosphere in said second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in the second internal space; wherein said oxygen partial pressure in said first internal space is controlled by an oxygen partial-pressure detector and an electrochemical pumping cell; said oxygen partial-pressure detector comprising a first oxygen-ion conductive solid electrolyte which at least defines the first internal space and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside the first internal space, respectively, said oxygen partial-pressure detector generating an electromotive force corresponding to a difference between the oxygen partial pressure within the first internal space and an oxygen partial pressure outside the first internal space; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines the first internal space and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside the first internal space, respectively, said electrochemical pumping cell pumping oxygen into or out of the first internal space; and a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that the electromotive force generated by the oxygen partial-pressure detector coincides with a predetermined value.

Claim 41

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in said first internal space to a level which does not substantially decompose NO; introducing an atmosphere in said first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in said atmosphere in said second internal space by (i) reducing or decomposing NO present in the atmosphere in said second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in said second internal space; wherein said oxygen partial pressure in said first internal space is controlled by an electrochemical sensing cell and an electrochemical pumping cell; said electrochemical sensing cell comprising a first oxygen-ion conductive solid electrolyte which at least defines said first internal space and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside said first internal space, respectively, said electrochemical sensing cell generating an electromotive force corresponding to a difference between the oxygen partial pressure within said first internal space and an oxygen partial pressure outside said first internal space; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines said first internal space and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside said first internal space, respectively, said electrochemical pumping cell pumping oxygen into or out of said first internal space; a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said electrochemical sensing cell coincides with a predetermined value; and a concentration of oxygen in said measurement gas being measured on the basis of a pumping current flowing through said electrochemical pumping cell.

Claim 42

A method of measuring a concentration of NOx as a gas component of a measurement gas, comprising the steps of: introducing the measurement gas containing the NOx component from an external measurement-gas space into a first internal space under a first diffusion resistance; controlling an oxygen partial pressure in said first internal space to a level which does not substantially decompose NO; introducing an atmosphere in said first internal space into a second internal space under a second diffusion resistance; and measuring the concentration of NO present in said atmosphere in said second internal space by (i) reducing or decomposing NO present in the atmosphere in said second internal space to produce oxygen, and (ii) measuring the oxygen partial pressure in said second internal space; wherein said oxygen partial pressure in said first internal space is controlled by an electrochemical sensing cell and an electrochemical pumping cell; said electrochemical sensing cell comprising a first oxygen-ion conductive solid electrolyte which at least defines said first internal space and a first pair of electrodes which contact said first oxygen-ion conductive solid electrolyte and which are disposed within and outside said first internal space, respectively, said electrochemical sensing cell generating an electromotive force corresponding to a difference between the oxygen partial pressure within said first internal space and an oxygen partial pressure outside said first internal space; said electrochemical pumping cell comprising a second oxygen-ion conductive solid electrolyte which at least partially defines said first internal space and a second pair of electrodes which contact said second oxygen-ion conductive solid electrolyte and which are disposed within and outside said first internal space, respectively, said electrochemical pumping cell pumping oxygen into or out of said first internal space; a voltage applied between said second pair of electrodes of said electrochemical pumping cell being regulated such that said electromotive force generated by said electrochemical sensing cell coincides with a predetermined value; and a concentration of oxygen in said measurement gas being measured on the basis of a pumping current flowing through said electrochemical pumping cell.