Exhaust gas sensing system and method for determining concentrations of exhaust gas constituents
View Patent ↗An exhaust gas sensing system and a method for determining concentrations of exhaust gas constituents are provided. The exhaust gas sensing system includes a NH 3 sensing cell, a NO 2 sensing cell, a NO x pumping cell, and a current sensor that detects an electrical current flowing through the NO x pumping cell. A computer determines a NO 2 concentration value, a NH 3 concentration value, a NO concentration value, and a NO x concentration value based on signals from the NH 3 sensing cell, the NO 2 sensing cell, and the current sensor.
1. An exhaust gas sensing system, comprising:
a NH 3 sensing cell configured to generate a first voltage indicative of a combination of a NH 3 concentration and a NO 2 concentration in exhaust gases communicating with the NH 3 sensing cell;
a NO 2 sensing cell configured to generate a second voltage indicative of a NO 2 concentration in exhaust gases communicating with the NO 2 sensing cell;
a NO x pumping cell electrically coupled to a voltage source that is configured to generate an electrical current through the NO x pumping cell, the magnitude of said electrical current indicative of combination of a NO concentration, a NO 2 concentration, and a NH 3 concentration in exhaust gases communicating with the NO x pumping cell;
a current sensor configured to measure the electrical current flowing through the NO x pumping cell and to output a current measurement signal indicative of a magnitude of the electrical current;
a computer configured to receive the first voltage, the second voltage, and the current measurement signal, the computer further configured to determine a NO 2 concentration value indicative of the NO 2 concentration in the exhaust gases communicating with the NO 2 sensing cell based on the second voltage;
the computer further configured to determine a NH 3 concentration value indicative of the NH 3 concentration in the exhaust gases communicating with the NH 3 sensing cell based on the first voltage and the NO 2 concentration value;
the computer further configured to determine a NO concentration value indicative of a NO concentration in the exhaust gases communicating with the NO x pumping cell based on the current measurement signal, the NO 2 concentration value, and the NH 3 concentration value;
the computer further configured to determine a NO x concentration value based on the NO concentration value and the NO 2 concentration value; and
the computer further configured to store the NO 2 concentration value, the NH 3 concentration value, the NO concentration value, and the NO x concentration value in a memory device.
2. The exhaust gas sensing system of claim 1 , wherein the NH 3 sensing cell and the NO 2 sensing cell are disposed in a first exhaust gas sensor and the NO x pumping cell is disposed in a second exhaust gas sensor that is not a part of the first exhaust gas sensor.
3. The exhaust gas sensing system of claim 1 , wherein the NH 3 sensing cell, the NO 2 sensing cell, and the NO x pumping cell are disposed in an exhaust gas sensor.
4. A method for determining concentrations of exhaust gas constituents, comprising:
generating a first voltage utilizing a NH 3 sensing cell that is indicative of a combination of a NH 3 concentration and a NO 2 concentration in exhaust gases communicating with the NH 3 sensing cell;
generating a second voltage utilizing a NO 2 sensing cell that is indicative of a NO 2 concentration in exhaust gases communicating with the NO 2 sensing cell;
generating an electrical current utilizing a voltage source that is electrically coupled to a NO x pumping cell wherein the magnitude of the electrical current is indicative of combination of a NO concentration, a NO 2 concentration, and a NH 3 concentration in exhaust gases communicating with the NO x pumping cell;
measuring the electrical current flowing through the NOx pumping cell utilizing a current sensor and outputting a current measurement signal from the current sensor indicative of a magnitude of the electrical current;
receiving the first voltage, the second voltage, and the current measurement signal at a computer;
determining a NO 2 concentration value indicative of the NO 2 concentration in the exhaust gases communicating with the NO 2 sensing cell based on the second voltage, utilizing the computer;
determining a NH 3 concentration value indicative of the NH 3 concentration in the exhaust gases communicating with the NH 3 sensing cell based on the first voltage and the NO 2 concentration value, utilizing the computer;
determining a NO concentration value indicative of a NO concentration in the exhaust gases communicating with the NO x pumping cell based on the current measurement signal, the NO 2 concentration value, and the NH 3 concentration value, utilizing the computer;
determining a NO x concentration value based on the NO concentration value and the NO 2 concentration value, utilizing the computer; and
storing the NO 2 concentration value, the NH 3 concentration value, the NO concentration value, and the NO x concentration value in a memory device, utilizing the computer.