Gas sensor device and control method thereof

Abstract

Provided are a gas sensor device and a control method thereof capable of starting cell deterioration judgment early and performing cell deterioration judgment with high accuracy. When the detection signal acquired from the single cell of the gas sensor (S15) reaches the start determination value, specifically, the output value of the single cell shows a value greater than 600 mV (S16: Yes) or the output value of the single cell When the value is less than 300 mV (S17: YES), a pulse voltage is applied to the cell (S18), and the initial internal resistance value is acquired based on the detection signal changed by the pulse wave (S20). The predetermined deterioration judgment value is compared with the initial internal resistance value (S21). By correcting the target resistance value of the cell used for heater temperature control (energization control) based on the comparison result (S28), the temperature of the cell can be stably kept constant regardless of cell deterioration.

Description

Technical field [0001] The present invention relates to a gas sensor device having a gas sensor for feedback control of air-fuel ratio in an internal combustion engine and a control method thereof. Background technique [0002] A gas sensor is known that has at least one cell composed of a solid electrolyte body and a pair of electrodes, and detects the concentration of a specific gas such as oxygen. The solid electrolyte body is activated as the temperature rises, and an electromotive force is generated between a pair of electrodes according to the oxygen concentration difference between the two atmospheres separated by the solid electrolyte body. The solid electrolyte body is heated by the heat of exhaust gas discharged from the internal combustion engine. On the other hand, a heater may be provided in order to activate the solid electrolyte body in advance. In addition, since the internal resistance value of the cell has a correlation with the temperature, the temperature con...

AI Technical Summary

Problems solved by technology

[0007] However, in Patent Document 1, in order to determine the deterioration of the cell, the cell must be activated sufficiently to obtain the correlation between the internal resistance value of the cell and the temperature, and it is also necessary to start driving the engine until it can be activated. Time to start degradation detection

Furthermore, since the deterioration of the cell is not directly judged but is indirectly judged based on the power supplied to the heater, there is a problem that the accuracy of the deterioration detection is poor.

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