Controller of wide-range exhaust gas oxygen sensor capable of outputting reference pump current

Abstract

The invention discloses a controller of a wide-range exhaust gas oxygen sensor capable of outputting reference pump current. The controller mainly comprises a digital signal processor, a temperature control module, a pump current control module and a man-machine interface module, the temperature control module adopts an alternating current constant current source method to measure the internal resistance of an oxygen concentration difference battery to indirectly detect the temperature of the sensor; direct-current bias current output by an alternating-current constant-current source serves as reference pump current of the sensor, and temperature control is carried out by adjusting voltage at the two ends of a heater; and an analog-to-digital converter on a digital signal processor realizes signal acquisition of oxygen concentration difference potential and pump current. The controller can output the stable reference pump current required by the wide-range exhaust gas oxygen sensor, realizes high-precision and real-time control over the temperature and the pump current of the sensor, and is particularly suitable for accurate measurement of the air-fuel ratio of an automobile engine.

Description

technical field [0001] The invention relates to the field of air-fuel ratio detection of automobile engines, and is a controller of a wide-area exhaust gas oxygen sensor, specifically for a wide-area exhaust gas oxygen sensor that requires an external reference pump current, with a digital signal processor (DSP) as the core , a controller that can realize high-precision and real-time control of the wide-area exhaust gas oxygen sensor temperature and pump current, and is used for accurate measurement of the air-fuel ratio of automobile engines. Background technique [0002] With the continuous improvement of automobile exhaust emission and fuel consumption requirements, the traditional switch-type oxygen sensor cannot meet the requirements of high emission standards and lean-burn engine air-fuel ratio control, and is replaced by a wider measurement range of wide-area exhaust gas oxygen (Universal Exhaust Gas Oxygen, referred to as UEGO) sensor. It can provide accurate air-fu...

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Problems solved by technology

The controller includes a heating module, a power module and a control module. However, the UEGO controller composed of analog circuits has poor reliability and low control accuracy.

At present, no literature has proposed a method to obtain the internal resistance of the oxygen concentration battery of the UEGO sensor. A UEGO sensor heating method and its control circuit published in the Chinese invention patent (Zhou Shuyan, Lu Zhaozhen, Zhang Lei, Yang Pengxiang, Kou Wei, Yang Yuanfei . Wide-area oxygen sensor heating method and its control circuit, 201510658186.4, application date: 2015.10.12.), the comparator circuit is used to judge whether the internal resistance of the UEGO sensor is the size when it reaches the working temperature, but it cannot be accurately obtained The size of the internal resistance leads to low steady-state accuracy of temperature control

A controller for a wide-area oxygen sensor published in a Chinese invention patent (Zhang Xiaojuan, Xie Jianjun, Zou Jie, Jian Jiawen, Li Hui, Zhou Zhanyun. A controller for a wide-area oxygen sensor, 201710306299.7, application date 2017.5.4) also Using the comparison circuit to judge the temperature, the accurate internal resistance value cannot be obtained, and the temperature control accuracy is not high

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