Patent ID: 7802463
Filing Date: 2010-09-28
Classification: F02D

Abstract:
1. A sensor control apparatus for outputting a detection signal that changes in accordance with an air-fuel ratio while making use of exhaust gas of an internal combustion engine, the sensor control apparatus comprising: an amplification circuit which can be selectively brought into a first state and a second state through switching of a gain of the amplification circuit itself; and a current detection resistor which has a predetermined resistance and detects current flowing through the gas sensor element, wherein in the first state, the amplification circuit amplifies the detection signal with a relatively small gain and outputs a first output signal which changes in accordance with the detection signal corresponding to an air-fuel ratio within a relatively wide first air-fuel ratio zone; in the second state, the amplification circuit amplifies the detection signal with a relatively large gain and outputs a second output signal which changes in accordance with the detection signal corresponding to an air-fuel ratio within a relatively narrow second air-fuel ratio zone contained in the first air-fuel ratio zone, a voltage generated across the current detection resistor is used as the detection signal, and the amplification circuit is a differential amplification circuit which performs differential amplification of potentials at opposite ends of the current detection resistor.