Method and apparatus for diagnosing an abnormality of a gas-concentration measuring apparatus

Abstract

In an activation state of a sensor device, when voltage on the connection points between the sensor device and the sensor control circuit becomes a preset abnormal value, electric cut off is made between the sensor control circuit and the connection point. Then, the delivery of power to the heater is ceased to lower the temperature of the cells to a below of an activation temperature, thereby increasing the internal resistance of the cell. Thereafter, the sensor control circuit supplies to the sensor device a current in a degree not to damage the sensor device, to detect voltages on the connection points at that time. By comparing between the voltages on the respective connection points detected, a content and location of abnormality occurred is identified for the sensor device.

Description

technical field [0001] The invention relates to a method and a device for diagnosing the abnormality of a gas concentration measuring device. Background technique [0002] In the related art, in the combustion control of internal combustion engines including gasoline engines, there is a known combustion control method in which the fuel supply amount is placed under feedback control in response to a predetermined partial exhaust gas concentration, by controlling the air and fuel supplied to the internal combustion engine The air / fuel ratio of the mixed gas to reduce the CO and NO in the exhaust gas X and HC. [0003] As a gas sensor for controlling such an air / fuel ratio, an oxygen sensor, a full-range air / fuel ratio sensor (also referred to as a UEGO sensor) and a NO sensor are known. X (nitrogen oxide) sensor. The oxygen sensor is provided with a cell having electrodes on both surfaces of its solid electrolyte based on zirconia or the like such that one of the electrodes...

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Problems solved by technology

[0006] Meanwhile, in the aforementioned abnormality diagnosis method, the abnormality diagnosis is in a state where the battery is kept at a predetermined temperature by the heater (in other words, in the battery activation state), so there is a problem that, at the relevant time, by making the abnormality diagnosis current flow In the case of abnormal diagnosis based on the battery voltage, the voltage required for abnormal diagnosis may not be output to the corresponding terminals of the battery.

[0008] In order to avoid this problem, it is considered to increase the abnormal diagnosis current flowing through the battery in the activated state, but this requires a large capacity of the power supply, which leads to an increase in cost

At the same time, there is another problem, that is, a large current flows through the battery, causing the battery to deteriorate rapidly

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