Nitrogen oxygen sensor heating detection apparatus and control method thereof

Abstract

The invention provides a nitrogen oxygen sensor heating detection apparatus and a control method thereof. The apparatus comprises a heating detection module, a voltage conversion module and a single chip microcomputer. The heating detection module is used for heating the thermal resistor of a nitrogen oxygen sensor heating layer Pt and monitoring the resistance value of the Pt thermal resistor in real time; the heating detection module comprises a first switch K1, a second switch K2, a constant current source, a first resistor R1 and a second resistor R2; the single chip microcomputer is used for obtaining temperatures of an nitrogen oxygen sensor, and controlling opening and closing of the first switch K1 or the second switch K2 so as to keep the working temperatures of the nitrogen oxygen sensor between 600 DEG C and 800 DEG C. According to the invention, a heating portion and a detection portion are separate, which guarantees that the nitrogen oxygen sensor is not in a heating state in measurement, thereby accurately measuring a specific temperature of the nitrogen oxygen sensor in some state. A tri-linear Pt thermal resistance measurement method is employed, thereby reducing influence of a Pt heat resistance heating lead to measurement results, and obtaining more accurate measurement results.

Description

technical field [0001] The invention belongs to the technical field of automobile exhaust treatment, and more specifically relates to a heating detection device of a nitrogen oxygen sensor and a control method thereof. Background technique [0002] Exhaust gas emitted by automobiles has become the main source of NOx pollutants in the atmosphere. Due to the improvement of national exhaust emission standards, real-time detection and processing of NOx emissions in exhaust gas is required, and the nitrogen and oxygen sensor is one of the core components of the detection system. . [0003] The nitrogen and oxygen sensor is composed of an electrochemical layer and a heating layer. The electrochemical layer mainly completes a series of electrochemical and catalytic decomposition reactions to realize the measurement of NOx gas; the heating layer mainly heats the nitrogen and oxygen sensor to make it reach the electric The temperature required for the electrochemical and catalytic r...

AI Technical Summary

Problems solved by technology

However, in the existing method, the heating process and the detection process of the nitrogen and oxygen sensor are carried out at the same time, and the resistance value of the Pt thermal resistance of the heating layer of the nitrogen and oxygen sensor at a specific temperature cannot be accurately measured, so that the nitrogen cannot be accurately measured. The temperature of the oxygen sensor; secondly, since the existing nitrogen and oxygen sensor uses constant voltage for continuous heating, it is necessary to add a fixed-value resistor of 0.2Ω~0.5Ω to the control circuit, and there will be 1A~2A in the control circuit. The current passes through this fixed-value resistor, resulting in a large power consumption of this resistor, which makes the temperature of the circuit board rise and affects the normal operation of the chip on the control circuit

Moreover, usually the Pt thermal resistance adopts a two-wire measurement method, and the measured Pt thermal resistance value is not accurate. Therefore, there is currently no method that can ensure the normal operation of the nitrogen and oxygen sensor at a temperature of 600 ° C to 800 ° C.

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