| 摘要 |
PURPOSE:To make it possible to utilize all of air/fuel ratio sensors, by connecting a characteristic correction circuit to a pump current control means and an oxygen pump element in series so that a pump current is increased and decreased at a predetermined ratio to supply the increased and decreased pump current to the oxygen pump element. CONSTITUTION:Characteristic correction circuits 30, 40 having the same structure are connected in directions opposite to each other through a pump cell 20 and operated as a reversal amplifying circuit with an amplifying ratio (n) using operational amplifiers OP1, OP2 and resistors R2, nR2 and + or -Ip1R1V is applied to the + terminal thereof as the reference potential of the cell 20 while voltage of + or -(Ip1+Ip2) R1V is applied to the - terminal thereof. Therefore, the current Ip2 flowing to a resistor mR1 is expressed by a predetermined formula. That is, the current Ip0 from a controller 10 is absorbed by Ip2 by the circuit 30 to be supplied to the cell 20 and the current Ip1 flowing through the cell 20 is added to the current Ip2 by the circuit 40 and the added current is returned to the controller 20 as the current Ip0. Therefore, correction can be performed by an arbitrary method using the circuits 30, 40. |
