Claims
- 1. A method for determining the NOx concentration in an exhaust gas from an internal combustion engine, which comprises:introducing some of the exhaust gas into a first measurement cell of a measurement sensor and establishing a first oxygen concentration in the first measurement cell through a first oxygen ion pump current; establishing a second reduced oxygen concentration in a second measurement cell through a second oxygen pump current, the second measurement cell being connected to the first measurement cell; measuring the NOx concentration by a third oxygen pump current from the second measurement cell; determining from the first oxygen ion pump current an air ratio signal representing a function of a λ value of the exhaust gas; determining from the air ratio signal a measurement error representing a deviation of the measured NOx concentration from a true NOx concentration; and correcting the measured NOx concentration with the measurement error.
- 2. The method according to claim 1, which further comprises:determining a substantially linear relationship between 1/λ and the measurement error in a calibration measurement by: exposing the measurement sensor to various gas mixtures; recording the measurement error and describing the measurement error as one of: a characteristic diagram; a characteristic curve; and a functional relationship; and varying at least the λ value and the NOx concentration in the gas mixtures.
- 3. The method according to claim 1, which further comprises carrying out the correction step by correcting with at least one of multiplication/addition calculation operations and subtraction calculation operations.
- 4. The method according to claim 1, which further comprises using a 1/λ value as the air ratio signal and carrying out the measurement error determining step by applying a substantially linear relationship between the 1/λ value and the measurement error.
- 5. The method according to claim 1, which further comprises using one of a characteristic curve and a characteristic diagram to determine the air ratio signal from the oxygen ion pump current.
Priority Claims (1)
Number |
Date |
Country |
Kind |
199 56 822 |
Nov 1999 |
DE |
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CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of International Application PCT/DE00/04128, filed Nov. 22, 2000, which designated the United States and was not published in English.
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A |
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Non-Patent Literature Citations (3)
Entry |
Wiedenmann et al “Automotive Electronics Handbook”, Chapter 6 “Exhaust Gas Sensors”, pp. 6.1-6.23, 1995.* |
“Thick Film ZrO2NOx Sensor for the Measuremen of Low NOx Concentration” (Kato et al.), Society of Automotive Engineers, Publication 980170, 1998, pp. 69-77. |
“Performance of Thick Film NOx Sensor on Diesel and Gasoline Engines” (Kato et al.), Society of Automotive Engineers, Publication 97058, 1997, pp. 199-206. |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/DE00/04128 |
Nov 2000 |
US |
Child |
10/156483 |
|
US |