Knock detection apparatus for internal combustion engine and method for detecting failures thereof

摘要

A knock sensing apparatus for a multi-cylinder internal combustion engine has a knock sensor that generates an electrical output signal corresponding to vibrations of the engine. A level indicating means generates a first level signal indicating the level of the output signal of the knock sensor during a first period at least partially coinciding with the power stroke in a cylinder of the engine and a second level signal indicating the level of the output signal of the knock sensor during a second period. An averager forms an average of the second level signal over a prescribed period, and a threshold calculator calculates a threshold based on the average. A comparator compares the first level signal and the threshold and generates a signal indicating knocking when the first level signal exceeds the threshold.