| 摘要 |
PURPOSE:To accurately discriminate the air/fuel ratio of a supplied gaseous mixture even if an oxygen concn. detection element has irregularity, by comparing the output voltage of a voltage dividing resistor circuit with predetermined voltage and adjusting the air/fuel ratio of the supplied gaseous mixture corresponding to the comparing result. CONSTITUTION:The adjustment of a voltage dividing resistor circuit 21 is performed according to the following process. At first, an oxygen concn. sensor main body 41 is set in the exhaust pipe of a testing machine and the air/fuel ratio of the testing machine is set to a predetermined value to supply a pump current between the electrodes 5, 6 of an oxygen pump element 1 and the voltage Vs generated between the electrodes of a cell element 2 is measured to obtain a pump current Ip-voltage Vs characteristics. If said characteristic does not coincide with the desired characteristic shown by a solid line and is within an adjustable range, the voltage dividing ratio of the voltage dividing resistor circuit 21 is adjusted by the laser trimming of a resistor 21a to obtain the desired characteristic. |
