Patent ID: 8733157
Filing Date: 2014-05-27
Classification: G01L

Abstract:
1. An cylinder inner pressure detector for detecting a cylinder inner pressure of an internal combustion engine by converting a sensor signal from an analog signal to a digital signal, the sensor signal being output from a cylinder inner pressure sensor in accordance with the cylinder inner pressure, the cylinder inner pressure detector comprising: a reference voltage output circuit for outputting a reference voltage having a level, which is selected among a plurality of levels according to a switching signal; a level shift circuit for shifting a level of the sensor signal by a selected level of the reference voltage toward a signal potential side corresponding to a low pressure side of the cylinder inner pressure and for outputting a shifted sensor signal; a first A/D converter circuit for receiving the shifted sensor signal from the level shift circuit and for converting the shifted sensor signal from an analog signal to a digital signal; and a controller for outputting the switching signal, which provides the reference voltage to be selected by the reference voltage output circuit in such a manner that the reference voltage has the level disposed on the signal potential side corresponding to the low pressure side from an offset voltage, and for detecting the cylinder inner pressure based on the digital signal output from the first A/D converter, wherein the offset voltage is defined by a voltage of the sensor signal when the cylinder inner pressure is minimum.