Methods of monitoring a combustion system

• US 4,372,155 A
• Filed: 05/20/1981
• Issued: 02/08/1983
• Est. Priority Date: 05/20/1981
• Status: Expired due to Term

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Schuetzle, Dennis, Colvin, Alex D., Butler, James W.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US06/265,316
• Time in Patent Office: 629 Days
• Field of Search: 73/116, 73/23, 73/114, 123/440, 123/489, 123/589, 123/230 PC, 60/276, 422/51, 422/98
• US Class Current: 73/114.72
• CPC Class Codes: F02B 77/086 Sensor arrangements in the exhaust, e.g. for temperature, misfire, air/fuel ratio, oxygen sensors
• CPC Class Codes: G01N 31/12 using combustion G01N25/20 takes precedence
• CPC Class Codes: G01N 33/0013 by a chemical reaction G01N33/0024 takes precedence

Abstract

This specification teaches a basic method of obtaining on a continuous basis an instantaneous indication of the air to fuel ratio of an air/fuel mixture being fed to a combustion process. The process may take place in an internal combustion engine or, for example, in a power plant. Modifications of the method are taught to obtain such information as the hydrogen to carbon ratio of the fuel being burned in the combustion process, the oxygen equivalence of the air/fuel mixture being burned, the air mass flow through the combustion process, the fuel mass flow through the combustion process, instantaneous fuel economy of a vehicle in which a combustion process is being carried out to propel the vehicle, and the oxygen concentration in the exhaust gases from the combustion process.

Claims

1. A method of obtaining on a continuous basis an instantaneous indication of the air to fuel ratio of an air/fuel mixture being fed to a combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but at a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis on output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material; and

continuously generating from said output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process.

2. A method of obtaining on a continuous basis an instantaneous indication of both the air to fuel ratio and the hydrogen to carbon ratio of an air/fuel mixture being fed to a combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but at a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continuously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis both a first output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material and another output signal indicative of the ratio of oxygen to carbon dioxide in said third stream of gaseous material; and

continuously generating from said first output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process; and

continuously generating from said other output signal a signal whose strength is proportional to the ratio of hydrogen to carbon in the fuel in the air/fuel mixture being burned in said combustion process.

3. A method of obtaining on a continuous basis an instantaneous indication of both the air to fuel ratio and the oxygen equivalence of an air/fuel mixture being fed to a combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continuously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis an output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material;

continuously generating from said output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being butned in the combustion process; and

continuously generating, also from said output signal generated by said mass spectrometer, a signal whose strength is related to the oxygen equivalence for the air/fuel mixture being burned in said combustion process.

4. The method of obtaining on a continuous basis an instantaneous indication of both the air to fuel ratio and the air mass flow of an air/fuel mixture being fed to a combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously injecting argon into said first stream of gaseous materials at a known, fixed mass injection rate;

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis both a first output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material and another output signal indicative of the ratio of argon to nitrogen in said third stream of gaseous materials;

continuously generating from said first output signal generated by said mass spectometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process; and

continuously generating from said other output signal and said known, fixed mass injection rate of argon a signal whose strength is proportional to the air mass flow through said combustion process.

5. A method of obtaining on a continuous basis an instantaneous indication of (a) the air to fuel ratio, (b) the air mass flow, and (c) fuel mass flow of an air/fuel mixture being fed to a combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously injecting argon into said first stream of gaseous materials at a known, fixed mass injection rate;

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but at a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectometer to generate on a continuous basis both a first output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material and another output signal indicative of the ratio of argon to nitrogen in said third stream of gaseous materials;

continuously generating from said output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process;

continuously generating from said other output signal and said known, fixed mass injection rate of argon a signal whose strength is proportional to the air mass flow through said combustion process; and

continuously generating from said first output signal and said signal whose strength is proportional to the air mass flow through said combustion process a signal whose strength is proportional to the fuel mass flow through said combustion process.

6. A method of obtaining on a continuous basis for a moving, internal combustion driven vehicle, an instantaneous indication of (a) the air to fuel ratio, (b) the air mass flow, (c) fuel mass flow, and (d) instantaneous fuel economy of an air/fuel mixture being fed to the combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously injecting argon into said first stream of gaseous materials at a known, fixed mass injection rate;

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but at a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis both a first output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material and another output signal indicative of the ratio of argon to nitrogen in said third stream of gaseous materials;

continuously generating from said output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process;

continuously generating from said other output signal and said known, fixed mass injection rate of argon a signal whose strength is proportional to the air mass flow through said combustion process;

continuously generating signals indicative of vehicle speed and fuel density; and

continuously generating from said other output signal and said signals indicative of vehicle speed and fuel density a signal whose strength is proportional to the instantaneous fuel economy of the driven vehicle.

7. A method of obtaining on a continuous basis an instantaneous indication of both the air to fuel ratio and the oxygen concentration in the exhaust gases of an air/fuel mixture being fed to the combustion process, which method comprises the steps of:

continuously passing an air/fuel mixture through a combustion process to generate a first stream of gaseous material which may contain (a) unburned fuel, (b) partially oxidized fuel, (c) carbon monoxide, (d) carbon dioxide, (e) water vapor, (f) nitrogen, (g) oxygen, (h) inert gases normally found in air, or (i) a mixture of any or all of (a) through (h);

continuously withdrawing into a volume at a first pressure below atmospheric pressure a sample portion of said first stream of gaseous material, said first pressure below atmospheric pressure being a pressure that, at the temperature of said sample portion continuously withdrawn, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a second stream of gaseous material that has the same compositional makeup on a volume percentage basis as said first stream of gaseous material but at a reduced pressure;

continuously providing a controlled source of oxygen addition to said second stream of gaseous material;

continuously controlling said controlled source of oxygen addition by application of a control signal thereto in a manner that said oxygen is added to said second stream of gaseous material at a rate proportional to the strength of said control signal applied to said controlled source of oxygen addition;

continously developing said control signal to a strength which results in said controlled source of oxygen addition adding to said second stream of gaseous material sufficient oxygen that there is after oxygen addition a predetermined amount of oxygen in excess of that required to stoichiometrically oxidize any (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide to (d) carbon dioxide and (e) water vapor;

continuously withdrawing into a volume at a second pressure substantially below said first pressure a sample portion of said second stream of gaseous material after said oxygen has reacted with (a) unburned fuel, (b) partially oxidized fuel, and (c) carbon monoxide, said second pressure being a pressure that, at the temperature of said sample portion continuously withdrawn from said second stream of gaseous material, said water vapor contained therein will not condense, said sample portion continuously withdrawn forming a third stream of gaseous material that has the same composition makeup based on fully oxidized carbon and hydrogen on a molar basis as said second stream of gaseous material plus added oxygen but at a reduced pressure;

continuously subjecting said third stream of gaseous material to analysis by a mass spectrometer to generate on a continuous basis an output signal indicative of the ratio of oxygen to nitrogen in said third stream of gaseous material;

continuously generating from said output signal generated by said mass spectrometer said control signal for application to said controlled source of oxygen, said control signal strength being generated in a manner that (1) when the oxygen signal of said third stream of gaseous material being measured by said mass spectrometer is at a predetermined level said control signal strength has a predetermined strength which ensures said predetermined amount of oxygen in excess of that required to stoichiometrically oxidize the aforementioned components is added to said second stream of gaseous material, and (2) when said oxygen signal of said third stream of gaseous material being measured by said mass spectrometer falls away from said predetermined level said control signal has a strength that ensures an amount of oxygen greater than said predetermined amount of oxygen is added to said second stream of gaseous material so that said measured amount of oxygen is returned to said predetermined level of oxygen, the instantaneous amount of oxygen being added to said second stream of gaseous material and the oxygen to nitrogen ratio being related to the fuel to air ratio of said air/fuel mixture being burned in the combustion process;

continuously generating a signal indicative of an oxygen to nitrogen ratio of a standard; and

continuously generating from said output signal and said signal indicative of said oxygen to nitrogen ratio of said standard a signal whose strength is proportional to the oxygen concentration in said first stream of gaseous materials.